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(11) | EP 4 799 816 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
| published in accordance with Art. 153(4) EPC |
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| (54) | LIQUID DISCHARGE HEAD AND RECORDING DEVICE |
| (57) A liquid ejection head includes a head body (9) including an ejection hole, a heat
sink (11) including a flow path (13), and a heat insulating member (15) interposed
between the head body (9) and the heat sink (11). |
TECHNICAL FIELD
[0001] The present disclosure relates to a liquid ejection head such as an inkjet head, and a recording device including the liquid ejection head.
BACKGROUND OF INVENTION
[0002] A known example of a liquid ejection head (e.g., inkjet heads) that ejects liquid (e.g., ink) toward a recording medium (e.g., paper) is a liquid ejection head that includes a heat sink (see, for example, Patent Literature 1 below). In Patent Literature 1, the liquid ejection head includes a substantially plate-shaped head body that ejects liquid from the lower surface thereof, and a substantially rectangular parallelepiped shaped housing that covers the back surface (upper surface) of the head body. Drive ICs (integrated circuits) that input drive signals to the head body are housed inside the housing. Openings are formed in two side surfaces of the housing, and heat sinks are disposed to close the openings. The heat sinks are composed of metal. The drive ICs are pressed against inner surfaces of the heat sinks and the outer surfaces of the heat sinks are exposed to the space outside the housing. In this way, the heat sinks contribute to dissipation of heat from the drive ICs.
[0003] The liquid ejection head of Patent Literature 2 listed below includes a flow path member for cooling drive ICs. The flow path member is a plate-shaped member that stands upright above a long head chip that ejects liquid from a lower surface thereof. The flow path member also includes a flow path that supplies liquid to the head chip. Along the flow path, multiple drive ICs are stacked on the wall surface of the flow path member with a heat transfer plate therebetween. Members called manifolds are disposed at both ends of the head chip, and the flow path member is connected to the head chip via the manifolds. Note that Patent Literature 2 does not disclose the materials of the flow path member, heat transfer plate, and manifolds.
CITATION LIST
PATENT LITERATURE
[0004]
Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2023-25267
Patent Literature 2: Japanese Unexamined Patent Application Publication No. 2023-90296
SUMMARY
[0005] In an aspect of the present disclosure, a liquid ejection head includes a head body, a heat sink, and a heat insulating member. The head body includes an ejection hole. The heat sink includes a flow path. The heat insulating member is interposed between the head body and the heat sink.
[0006] In an aspect of the present disclosure, a recording device includes the liquid ejection head.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007]
FIG. 1 is a side view of a recording device according to an embodiment.
FIG. 2 is a plan view of the recording device in FIG. 1.
FIG. 3 is a perspective view of a liquid ejection head of the recording device in FIG. 1.
FIG. 4 is an exploded perspective view of the liquid ejection head in FIG. 3.
FIG. 5 is a cross-sectional view taken along line V-V in FIG. 3.
FIG. 6 is an exploded perspective view of a head body of the liquid ejection head in FIG. 3.
FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. 6.
FIG. 8 is a side view illustrating a flow path of a heat sink in the liquid ejection head in FIG. 3.
FIG. 9 is a perspective view illustrating a heat insulating member of the liquid ejection head in FIG. 3.
FIG. 10 is an enlarged view of region X in FIG. 5.
FIG. 11 is a cross-sectional view taken along line XI-XI in FIG. 9.
FIG. 12 is a perspective view of a liquid ejection head according to another example.
FIG. 13 is a cross-sectional view illustrating the heat insulating member of the liquid ejection head and the surroundings thereof in FIG. 11.
FIG. 14 is a diagram for explaining image quality in printing carried out by a liquid ejection head according to a comparative example.
DESCRIPTION OF EMBODIMENTS
[0008] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that the drawings used in the following description are schematic drawings. Therefore, for example, the dimensional ratios and so forth in the drawings do not necessarily match the actual dimensional ratios and so forth. Furthermore, there may be cases where the dimensional ratios and so forth do not match from drawing to drawing. Certain shapes and/or dimensions etc. may be depicted in an exaggerated manner, and details may be omitted. However, this does not deny the possibility that the actual shapes and/or dimensions may be as illustrated in the drawings, or that the shapes and/or dimensions may be extracted from the drawings.
[0009] For convenience, a Cartesian coordinate system D1D2D3 may be added to the drawings, and terms such as a D1 direction, a D2 direction, and a D3 direction may be used. As can be understood from the descriptions given below, the term D1 direction may be replaced with the term longitudinal direction of the head and/or the direction perpendicular to the direction of relative movement between the head and the recording medium. The term D2 direction may be replaced with the term lateral direction of the head and/or the direction of relative movement. The term D3 direction may be replaced with the term normal direction to the ejection surface or back surface of the head body. A liquid ejection head and a recording device according to an embodiment may be used in any orientation. However, for convenience, terms may be used under the assumption that the +D3 side is upward.
(Overview of embodiments)
[0010] FIG. 3 is a perspective view mainly illustrating a head 3 (an example of a liquid ejection head) according to an embodiment. The head 3 performs recording (printing) on a recording medium (see printing paper P in FIG. 1, described later) facing a lower surface (ejection surface 5) of the head 3, for example. Specifically, multiple ejection holes 7 (see FIG. 7, described later) open in the ejection surface 5 of the head 3. Ink droplets (an example of liquid droplets) are ejected from the multiple ejection holes 7. As a result, multiple dots that form an image are formed on the recording medium.
[0011] FIG. 5 is a cross-sectional view taken along line V-V in FIG. 3. As illustrated in FIGs. 3 and 5, the head 3 includes, for example, a head body 9 that constitutes the ejection surface 5, and at least one heat sink 11 (two in the illustrated example) that contributes to dissipation of heat from the head 3 (more strictly, electronic components (described later) included in the head 3).
[0012] In the illustrated example, the head body 9 is, for example, a substantially plate-shaped member (in other words, a shape in which the thickness is smaller than the length and width; the same applies hereinafter) with the D3 direction as the thickness direction. The heat sinks 11 are substantially plate-shaped members facing the D2 direction disposed on the back surface (upper surface) of the head body 9. Each heat sink 11 includes a flow path 13 (FIG. 5) along which a coolant (for example, water) flows.
[0013] A heat insulating member 15 is interposed between the head body 9 and the heat sinks 11. The heat insulating member 15 is, for example, joined to the head body 9 and the heat sinks 11, thereby joining the head body 9 and the heat sinks 11 together. For example, the head body 9 and the heat sinks 11 are not in contact with each other.
[0014] In the above-described configuration, the heat sinks 11 include the flow paths 13, and this improves the effect of cooling electronic components compared to an embodiment in which the heat sinks 11 are simply plates. Therefore, for example, the electrical load of the electronic components can be increased. As a result, for example, the frequency at which ink droplets are ejected from the head body 9 can be increased, thereby improving printing speed.
[0015] On the other hand, if the cooling performance of the heat sinks 11 is high, an unintended cooling effect will occur in the portions of the head body 9 joined to the heat sinks 11. As a result, for example, an imbalance occurs in the temperature distribution in the head body 9. This imbalance in the temperature distribution causes, for example, the viscosity of ink in the head body 9 to become non-uniform, which in turn causes variations in the ejection characteristics from the multiple ejection holes 7.
[0016] However, by interposing the heat insulating member 15 between the heat sinks 11 and the head body 9, the above-mentioned drawback is resolved. The above-mentioned drawback (in other words, problem) would be less likely to occur if the heat sinks 11 did not include the flow paths 13. From another perspective, the heat insulating member 15 provides advantageous effects when used in combination with the flow paths 13. Note that, unlike in the description of the embodiments, when an invention that does not require the flow paths 13 is extracted from the present disclosure, the heat insulating member 15 does not need to be used in combination with the flow paths 13.
[0017] In an embodiment, unlike in the illustrated example, the heat sinks 11 and the head body 9 may be in direct contact with each other over a relatively small area at positions where the heat insulating member 15 is not disposed. Furthermore, the heat insulating member 15 may not contribute to joining the head body 9 and the heat sinks 11 to each other. Even in these cases, the heat insulating member 15 enables the contact area between the heat sinks 11 and the head body 9 to be reduced, thereby still achieving the above-mentioned effect.
[0018] An overview of embodiments has been given above. Hereinafter, the details of embodiments will be roughly described in the following order.
- 1. Printers in general (FIGs. 1 and 2)
- 2. Overall configuration of head (FIGs. 3 to 5)
- 3. Head body (FIGs. 3 to 7)
3.1. Front part
3.1.1. Flow path member
3.1.2. Actuator substrate
3.2. Back part
- 4. Heat sinks (FIGs 3 to 5 and 8)
- 5. Heat insulating member (FIGs. 3 to 5 and 9 to 11)
5.1. General points
5.2. Base
5.3. Ribs
5.4.Materials
- 6. Other examples of heads (FIGs. 12 and 13)
- 7. Experimental examples (FIG. 14)
- 8. Summary of embodiments
[0019] The description of the heat sinks 11 in Section 4 includes a description of the positional relationship between the flow paths 13 and drive ICs 37 (described later), and a description of how the heat sinks 11 and a head cover 25 (described later) are joined together. The description of the heat insulating member 15 in Section 5 includes a description of how the heat insulating member 15 and other members (such as the heat sinks 11) are joined together, and a description of the relationship between the thermal conductivity of the heat insulating member 15 and the thermal conductivity of other members.
(1. Printers in general)
[0020] FIG. 1 is a side view of a printer 1 including the head 3. FIG. 2 is a plan view of the printer 1.
[0021] The printer 1 may have various configurations, for example, known configurations, except for configurations related to the heat sinks 11 and the heat insulating member 15. The printer 1 illustrated in FIGs. 1 and 2 is merely an example. Below, the printer 1 will be briefly described in general using the printer 1 illustrated in FIGs. 1 and 2 as an example.
[0022] The printer 1 forms an image on the printing paper P by ejecting ink droplets downward from the heads 3 located above the printing paper P. Specifically, as illustrated in FIG. 2, one head unit 17 includes five heads 3. In each head unit 17, the five heads 3 are disposed in a staggered pattern when viewed in the D2 direction so that there are no gaps in the D1 direction. The printable range of each head unit 17 roughly spans the width (in the D1 direction) of the printing paper P. An image is formed by the heads 3 ejecting ink droplets while the printing paper P passes below the heads 3.
[0023] As can be understood from the above description, the printer 1 is configured as a so-called line printer. However, the printer 1 is not limited to a line printer. For example, the printer 1 may be a serial printer. In a serial printer, for example, the operation of moving the head (head unit) in a direction intersecting the transport direction of the printing paper P and transporting of the printing paper P are performed in an alternating manner. For convenience, in the description of the embodiments, a line printer may be assumed without being particularly mentioned.
[0024] The printer 1 includes a total of four head units 17. The four head units 17 are arranged, for example, in the transport direction of the printing paper P. The five heads 3 in each head unit 17 correspond to ink of the same color. The four head units 17 correspond to ink of different colors (four color inks). The four color inks are, for example, magenta (M), yellow (Y), cyan (C), and black (K). This allows the printer 1 to function as a color printer.
[0025] Unlike in the above description, the printer 1 may print in a single color, or conversely, may print in more than four colors. In other words, the number of colors is arbitrary. Two or more head units 17 may correspond to one color. Conversely, one head unit 17 may correspond to two or more colors, for example, by making one head 3 correspond to two or more colors, etc. The number of heads 3 included in one head unit 17 is arbitrary, and may be one. As can be understood from the above description, the printer 1 may include any number of heads 3.
[0026] The multiple heads 3 may be fixed to each other in each head unit 17 in any manner. FIGs. 1 and 2 illustrate a frame 21 including openings (not illustrated) through which the ejection surfaces 5 of the heads 3 are exposed downward.
[0027] The printer 1 prints, for example, on roll paper serving as the printing paper P. However, the printing paper P may also be sheet paper. The size of the printing paper P is also arbitrary. For example, the size of printing paper P may be small like a receipt, may be a size commonly used in offices, or may be large like a poster.
[0028] A transport device 19 for transporting the printing paper P may have any configuration. FIGs. 1 and 2 illustrate an example of a configuration in which the printing paper P is transported by rotating rollers that sandwich the printing paper P therebetween. Other configurations include, for example, a configuration in which the printing paper P is transported by transporting a belt that holds the printing paper P in place by suction, and a configuration in which the printing paper P is transported by rotating a drum around which the printing paper P is wrapped. In a broader concept, the transport device 19 is a moving unit that moves a head (3) and a recording medium (P) relative to each other.
[0029] As schematically illustrated in FIG. 3, the printer 1 includes an ink supply system 89 that supplies ink to each head 3. The ink supply system 89 may have any configuration. For example, the ink supply system 89 may include an ink tank 91 that stores ink, and an ink pump 93 that transports the ink from the ink tank 91 to the heads 3. The ink tank 91 may be replaceable, in which case the ink tank 91 may be considered to not be a component of the printer 1. The ink pump 93 is not limited to a pump that is generally considered to be a pump, and may be, for example, a component that applies pressure to the ink tank 91. The ink supply system 89 may have a configuration that recovers ink from the head 3 (in other words, a configuration that circulates ink).
[0030] As schematically illustrated in FIG. 3, the printer 1 includes a coolant supply system 95 that supplies a coolant (e.g., water) to the head 3. The coolant supply system 95 may be defined to include components for recovering the coolant. The coolant supply system 95 may have any configuration. For example, the coolant supply system 95 may include a coolant tank 97 that stores the coolant and a pump 99 that delivers the coolant from the coolant tank 97 to the head 3. The coolant that has undergone heat exchange with the head 3 may be returned to the coolant tank 97 (as in the illustrated example), or may not be returned (for example, may be discarded). The coolant supply system 95 may consist of equipment in a factory, etc., in which case the coolant supply system 95 may not be considered to be a component of the printer 1. The printer 1 or the factory, etc. may or may not include a heat pump for cooling the coolant.
[0031] The coolant is, for example, water. However, the coolant may be a liquid other than water (for example, antifreeze) or a gas (for example, air). Furthermore, ink ejected from the head 3 may be used as the coolant. In this case, unlike in the illustrated example, for example, the coolant supply system 95 may be omitted, and the flow paths 13 of the heat sinks 11 may be directly or indirectly connected to the flow paths of the head body 9 (for more details, see upper surface ports 85 described later). Then, ink may be supplied from the ink supply system 89 to the flow paths 13 of the heat sinks 11, and the ink that has absorbed heat in the heat sinks 11 may be supplied to the head body 9.
[0032] The printer 1 may have various other components in addition to those described above. Although not specifically illustrated, examples are given below.
[0033] Controller: For example, controls the head 3, the transport device 19, the ink supply system 89, and the coolant supply system 95.
[0035] Coating device: For example, evenly applies a transparent coating agent to the printing paper P.
[0037] The printer 1 may use the head 3 to apply a coating agent in addition to or instead of printing with colored ink.
(2. Overall configuration of head)
[0038] The head 3 may have various configurations, for example, known configurations, except for the configurations related to the heat sinks 11 and the heat insulating member 15. Below, the components of the head 3 in the illustrated example will be listed, and then the components other than the head body 9, the heat sinks 11, and the heat insulating member 15 will be briefly described.
[0039] As illustrated in FIG. 3, the head 3 may include the following components in addition to the head body 9, the heat sinks 11, and the heat insulating member 15, for example.
[0040] Head cover 25: For example, forms a housing 23 of the head 3 together with the heat sinks 11.
[0041] Connectors 27: For example, electrically connect the head 3 to other components in the printer 1 (for example, the controller described above).
[0042] Ink pipes 29: For example, connect the head body 9 to the ink supply system 89. May be regarded as a component of the ink supply system 89 rather than a component of the head 3.
[0043] Connecting parts 31: For example, connects the flow paths 13 of the heat sinks 11 to the coolant supply system 95. May be regarded as a component of the coolant supply system 95 rather than a component of the head 3.
[0044] Communication pipe 33: For example, connects the flow paths 13 of the two heat sinks 11. May be regarded as a component of the coolant supply system 95 rather than a component of the head 3.
[0045] Positioning tool 35: For example, positions the head 3 relative to the frame 21. May not be considered a component of the head 3.
[0046] FIG. 4 is an exploded perspective view of the head 3. As illustrated in this figure, the head 3 may further include the following components.
[0048] FPCs (flexible printed circuits) 39: For example, transmit signals related to the drive ICs 37.
[0049] Lower surface heater 41 and upper surface heater 43: For example, heat the head body 9 (and in a general concept, adjust the temperature).
[0051] Circuit boards 47: For example, include various electric circuits connected to the drive ICs 37.
[0052] As illustrated in FIGs. 4 and 5, the head body 9 includes the following components:
Front part 49: For example, constitutes the ejection surface 5.
Back part 51: For example, constitutes the back surface (surface on the +D3 side) of the head body 9.
[0053] The housing 23 is substantially shaped like, for example, a rectangular parallelepiped with an open bottom. The head cover 25 forms the upper surface and both side surfaces in the D1 direction out of the five surfaces of the housing 23. The two heat sinks 11 form the remaining two surfaces. The head cover 25 may be composed of any material. For example, the material may be a metal or resin. The metal may be, for example, aluminum or an aluminum alloy.
[0054] As described above, the head 3 includes the drive ICs 37, the FPCs 39, the circuit boards 47, and the connectors 27 as an electrical configuration for driving the head body 9. Signals input from a controller (not illustrated) to the connectors 27 are input to the drive ICs 37 via the circuit boards 47 and FPCs 39 in this order. The drive ICs 37 generate driving signals based on the input signals. The driving signals are input to the head body 9 via the FPCs 39. Each driving signal is, for example, a pulse signal having an electric potential of an appropriate magnitude.
[0055] Specific details (number, position, configuration, etc.) of the FPCs 39 are arbitrary. In the example in FIGs. 4 and 5, the head 3 includes two FPCs 39 disposed in a substantially symmetrical manner with respect to a plane of symmetry (not illustrated) parallel to the D1-D3 plane.
[0056] Each FPC 39 is, for example, a single-sided board including a conductor pattern on only one surface (hereinafter referred to as a "first surface"). The first surface in an edge region of the FPC 39 faces and is electrically connected to the upper surface of the front part 49. The FPC 39 extends toward the outside of the housing 23 in the D2 direction in the edge region, and then bends toward the opposite side from the first surface and extends upward. The first surface in the portion extending upward faces the inner surface of the corresponding heat sink 11. Drive ICs 37 are mounted on the region of the first surface facing the inner surface of the heat sink 11.
[0057] Unlike in the illustrated example, for example, one FPC 39 may be provided, with the central region of the FPC 39 connected to the front part 49 and the end regions of the FPC 39 extending upward. Furthermore, the FPC 39 may be a double-sided board including conductor patterns on both sides.
[0058] The specific details (number, position, configuration, etc.) of the drive ICs 37 is arbitrary. In the example in FIGS. 4 and 5, multiple drive ICs 37 (five in the example in FIG. 4) are arranged in a row in the D1 direction on the first surface of each FPC 39. In other words, the multiple drive ICs 37 are disposed at the same positions as each other in the D3 direction. The drive ICs 37 have a substantially rectangular parallelepiped shape with a longitudinal direction, and are mounted with the longitudinal direction oriented along the D1 direction. Unlike in the illustrated example, for example, the drive ICs 37 may be mounted on both surfaces of each FPC 39, which is consists of a double-sided board.
[0059] The pressing member 45 includes, for example, a support portion 45a that is substantially U-shaped when viewed in the D1 direction, and elastic members 45b located on the outside of side surfaces of the U-shape. The pressing member 45 presses the drive ICs 37 via the FPCs 39 using the elastic members 45b, thereby pressing the drive ICs 37 against the heat sinks 11. The force pressing the drive ICs 37 may be obtained via the restoring force of the support portion 45a and/or the elastic members 45b. The materials of the support portion 45a and the elastic members 45b are arbitrary. For example, the thermal conductivity of these materials may be higher or lower than that of the heat insulating member 15.
[0060] The lower surface heater 41 is, for example, sheet-shaped and overlaps the lower surface of the back part 51, as illustrated in FIGs. 4 and 5. The upper surface heater 43 is, for example, sheet-shaped and overlaps the upper surface of the back part 51. These heaters contribute, for example, to increasing the temperature of the ink and reducing the viscosity of the ink. These heaters generate heat when power is supplied via, for example, the circuit boards 47 (and are controlled from another perspective). The target temperature may be a temperature within the range of room temperature (5°C or higher and 35°C or lower), or may be a temperature higher than room temperature.
[0061] In the example in FIGs. 3 and 4, two ink pipes 29 are provided. The two ink pipes 29 may, for example, both be used to supply ink of the same color to the head body 9. Alternatively, the two ink pipes 29 may supply ink of different colors. Alternatively, one ink pipe 29 may be used to supply ink, and the other ink pipe 29 may be used to collect ink.
[0062] As can be understood from the above description, the head body 9 may or may not be circulation type head body that circulates ink. For convenience, in the description of the embodiments, the head body 9 may be described with the assumption that the head body 9 is not a circulation type head body unless otherwise specified.
[0063] Upper surface ports 85 (FIG. 4), through which the head body 9 receives ink, open in regions of the upper surface of the back part 51 that are located outside the housing 23. Consequently, the ink pipes 29 connected to the upper surface ports 85 are located outside the housing 23. Unlike in the illustrated example, the upper surface ports 85 may open in regions that are covered by the housing 23. Then, the ink pipes 29 may be inserted into the housing 23 from the upper surface of the housing 23.
[0064] The connecting parts 31 are, for example, members that connect the flow paths 13 of the heat sinks 11 to pipes (including the communication pipes 33), and the specific configuration thereof is arbitrary. The pipes (including the communication pipes 33) may be flexible or inflexible. The specific role of the communication pipes 33 will be described in the description of the heat sinks 11.
(3. Head body)
[0065] As described above, the head body 9 includes the front part 49 and the back part 51. The front part 49 has an ejection surface 5 and directly contributes to the ejection of ink droplets. The back part 51, for example, contributes to supplying ink to the front part 49 (supply and recovery in the case of a circulation type), contributes to improving the strength of the head body 9, and/or contributes to fixing the head body 9 to the frame 21. The front part 49 and the back part 51 may be joined together using an adhesive (for example, a thermosetting resin) (not illustrated) interposed between the upper surface of the former and the lower surface of the latter.
(3.1. Front part)
[0066] As illustrated in FIG. 4, the front part 49 has a substantially plate-like shape. The planar shape is, for example, substantially rectangular with the D1 direction as the longitudinal direction. As illustrated in FIG. 5, the front part 49 includes a flow path member 53 including a flow path (including ejection holes 7) through which ink flows, and an actuator substrate 55 that applies pressure to the ink in order to eject the ink.
(3.1.1. Flow path member)
[0067] FIG. 6 is an exploded perspective view of the head body 9. The flow path member 53 is a substantially plate-shaped member. The flow path member 53 includes at least one port 57 (eight in the illustrated example), at least one common flow path 59 (four in the illustrated example), and multiple individual flow paths 61 (only some of which are illustrated) as flow paths. Each individual flow path 61 includes an ejection hole 7 (FIG. 7). Ink flows through the ports 57, the common flow paths 59, and the individual flow paths 61 in this order, and is ejected from the ejection holes 7.
[0068] The ports 57 open at the back surface (upper surface) of the flow path member 53. The multiple common flow paths 59 extend from the ports 57 along the ejection surface 5 inside the flow path member 53, and extend parallel to one another. The multiple individual flow paths 61 are arranged along each common flow path 59 and across substantially the entire length of the common flow paths 59. However, for convenience, only some of the individual flow paths 61 (and further only pressure chambers 67, which are part of each individual flow path 61, as described below) are illustrated in FIG. 6. Furthermore, although the individual flow paths 61 would ideally be illustrated by dotted lines, just like the common flow paths 59, because the individual flow paths 61 are small compared to the size of the figure, the individual flow paths 61 are illustrated by solid lines for convenience.
[0069] The number of common flow paths 59 and the direction in which the common flow paths 59 extend are arbitrary, and the number of ports 57 and the opening positions thereof are also arbitrary. In the example in FIG. 6, the common flow paths 59 extend along (for example, parallel to) the longitudinal direction (D1 direction) of the flow path member 53. From another perspective, the multiple common flow paths 59 include two or more common flow paths 59 that are at different distances from the long sides of the flow path member 53. The ports 57 are connected to both ends of the common flow paths 59. From another perspective, the ports 57 are located at the short sides of the flow path member 53 with respect to the common flow paths 59 (or, from another perspective, the actuator substrate 55). Ink flows from both ends of the common flow paths 59 toward the center.
[0070] Examples other than that illustrated in the drawings will be given. The direction in which the multiple common flow paths 59 extend may be the D2 direction instead of the D1 direction, or may be inclined at an angle of 45° or less with respect to the D1 direction or the D2 direction. One or more common flow paths 59 extending along the D1 direction may be arranged in the D1 direction. The multiple common flow paths 59 may merge at one or both ends to form a manifold-like flow path. That is, multiple common flow paths 59 do not need to be independent of each other within the flow path member 53. The ports 57 may be located on the long sides of the flow path member 53 with respect to the common flow paths 59 (and/or the actuator substrate 55). The ports 57 may be connected to only one end of the common flow paths 59, rather than to both ends. Ink may flow from one end of the common flow paths 59 to the other end.
[0071] The multiple ejection holes 7 (from another perspective, the multiple individual flow paths 61) are arranged in one or more rows (for example, two or four rows) along each common flow path 59, and the multiple common flow paths 59 are arranged in parallel with each other, so as to be arranged in multiple rows (in other words, two-dimensionally) on the ejection surface 5. This improves the resolution of printed images (as will be described later with reference to FIG. 14). The ejection holes 7 may also be provided in a single row.
[0072] FIG. 7 is a cross-sectional view of the front part 49 taken along line VII-VII in FIG. 6. This figure illustrates a region roughly corresponding to one common flow path 59 (lateral cross section thereof) and one individual flow path 61 (vertical cross section thereof).
[0073] The flow path member 53 is formed, for example, by stacking a plurality of plates 63. Multiple voids (for example, through holes and recesses) that form the flow paths are formed in the plates 63. The thickness and number of plates 63 may be set as appropriate depending on the shape of the flow paths, etc. The multiple plates 63 may be formed from an appropriate material. For example, the multiple plates 63 are formed from metal or resin. The thickness of the plates 63 is, for example, 10 µm or more and 300 µm or less. The plates 63 are fixed to each other, for example, by an adhesive, which is not illustrated, (for example, a thermosetting resin) that is interposed between the plates 63.
[0074] Each individual flow path 61 includes, for example, in order from the common flow path 59 side, a communication path 65, a pressure chamber 67, a descender 69, and the corresponding ejection hole 7. When pressure is applied to the pressure chamber 67 by an actuator 71 (described later) included in the actuator substrate 55, ink inside the descender 69 is pushed toward the ejection hole 7, and an ink droplet is ejected from the ejection hole 7. After that, the pressure chamber 67 is replenished with ink from the common flow path 59 via the communication path 65. The specific shape and dimensions of each of these parts are arbitrary.
(3.1.2. Actuator substrate)
[0075] The number, shape, and dimensions of the actuator substrate 55 are arbitrary. In the example in FIG. 6, one actuator substrate 55 is provided having an area that covers all of the pressure chambers 67. The shape of the actuator substrate 55 is substantially rectangular with four sides parallel to the four sides of the flow path member 53, and the longitudinal direction is also the same as the longitudinal direction of the flow path member 53. Unlike in the illustrated example, for example, multiple actuator substrates 55 may be arranged in the longitudinal direction of the flow path member 53.
[0076] As indicated by the reference symbols in FIG. 7, the actuator substrate 55 includes actuators 71, each of which is provided for a corresponding one of the pressure chambers 67. Each actuator 71 is, for example, a piezoelectric actuator that applies pressure to ink via mechanical distortion of a piezoelectric body. The piezoelectric actuator is, for example, a so-called unimorph type piezoelectric actuator. However, the actuator 71 may also be configured as another type of piezoelectric actuator, such as a bimorph type piezoelectric actuator.
[0077] The unimorph actuator 71 includes, for example, in this order from the flow path member 53 side, a vibration plate 73, a common electrode 75, a piezoelectric layer 77, and an individual electrode 79. The vibration plate 73, the common electrode 75, and the piezoelectric layer 77 extend, for example, over substantially the entire actuator substrate 55. That is, these components are provided in a shared manner for multiple pressure chambers 67. The individual electrodes 79 are each provided for a corresponding pressure chamber 67. Each individual electrode 79 includes a body 79a that overlaps the corresponding pressure chamber 67, and a lead out electrode 79b that is led out from the body 79a and to which a drive signal is input. The body 79a has substantially the same shape and dimensions as the pressure chamber 67. The specific material and thickness of each layer are arbitrary.
[0078] At least the portion of the piezoelectric layer 77 that is sandwiched between the body 79a of the individual electrode 79 and the common electrode 75 is polarized in the thickness direction. Therefore, for example, when an electric field (voltage) is applied in the polarization direction of the piezoelectric layer 77 by the body 79a and the common electrode 75, the piezoelectric layer 77 contracts in a direction along the layer. This contraction is regulated by the vibration plate 73. As a result, the actuator 71 bends and deforms in a convex manner toward the pressure chamber 67. When an electric field (voltage) is applied in the opposite direction from that mentioned above by the body 79a and the common electrode 75, the actuator 71 bends and deforms in the direction away from the pressure chamber 67. By utilizing this bending deformation, the volume of the pressure chamber 67 can be changed, and pressure can be applied to the ink inside the pressure chamber 67.
[0079] Each FPC 39 is disposed such that a region at one end thereof faces the actuator substrate 55, and pads (not illustrated) located on the surface of this region are connected to the lead out electrodes 79b. Drive signals generated by the drive ICs 37 are input to the lead out electrodes 79b via the FPC 39. The actuator substrate 55 also includes a connection electrode (not illustrated) connected to the common electrode 75 at an appropriate position (for example, outside the region where the multiple pressure chambers 67 are arranged). The FPC 39 includes a pad (not illustrated) connected to the connection electrode. A constant potential (for example, a reference potential) is applied to the common electrode 75 from the FPC 39.
(3.2. Back part)
[0080] As illustrated in FIGs. 4 and 6, the back part 51 is, for example, a substantially plate-shaped member. The planar shape thereof is, for example, a substantially rectangular shape having four sides parallel to the four sides of the front part 49 and whose longitudinal direction coincides with the longitudinal direction of the front part 49. As illustrated in FIG. 6, the back part 51 includes, for example, a substantially rectangular-parallelepiped-shaped body 51a and a flange 51b protruding outward from an upper region of the outer peripheral surface (side surface) of the main body 51a.
[0081] The main body 51a has a lower surface that is joined to the back surface (upper surface) of the flow path member 53. A recess 81 (FIG. 6) is formed on the lower surface of the body 51a in order to avoid contact with the actuator substrate 55. The planar shape and dimensions thereof are, for example, slightly larger than those of the actuator substrate 55. In other words, the back part 51 and the flow path member 53 are joined to each other in a frame-shaped region in plan view.
[0082] Lower surface ports 83 (FIG. 6) that connect to the ports 57 of the flow path member 53 open at the lower surface of the main body 51a. One lower surface port 83 has a size that spans, for example, multiple ports 57 (four in the example of FIG. 6). Unlike in the illustrated example, the lower surface ports 83 and the ports 57 may be provided with a one-to-one correspondence. As described above, the positions of the ports 57 are arbitrary, and the positions of the lower surface ports 83 may also be provided at arbitrary positions depending on the positions of the ports 57.
[0083] As illustrated in FIG. 4, the upper surface ports 85 open at the upper surface of the back part 51 (the back surface of the head body 9). The upper surface ports 85 are connected to the lower surface ports 83 via flow paths, which are not illustrated, inside the back part 51. Ink flows sequentially through the upper surface ports 85, the flow paths (not illustrated), and the lower surface ports 83, and is supplied to the ports 57. The upper surface ports 85 may open at the upper surface of the body 51a, or may open at the upper surface of the flange 51b.
[0084] As illustrated in FIGs. 4 and 6, the body 51a is provided with slits 87. The slits 87 penetrate through the body 51a in the D3 direction and extend in the D1 direction in regions that overlap the recess 81 when viewed in the D3 direction. As illustrated in FIG. 5, the FPCs 39 are inserted through the slits 87.
[0085] For example, when the lower part of the body 51a is inserted into the opening of the frame 21, the flange 51b engages with the frame 21 and contributes to fixing the head 3 to the frame 21. In addition, for example, the flange 51b contributes to expanding the area of the back surface of the head body 9. This increases the joining area with the heat insulating member 15 and increases the degree of freedom when arranging the upper surface ports 85, for example.
[0086] The specific dimensions of each part are arbitrary. For example, the wall portion of the recess 81 in the body 51a may have either a larger thickness or a larger height. Either the bottom surface (+D3 side) of the recess 81 or the lower surface of the flange 51b may be located lower. The flange 51b may have either a larger width or a larger thickness.
[0087] The shape of the back part 51 may have a shape other than that described above. For example, the flange 51b may not be provided. Furthermore, the flange 51b may not be provided around the entire periphery, but may be provided only on the short sides or only on the long sides. The body 51a may include a portion that protrudes above the flange 51b, and the slits 87 may open in that portion.
[0088] Although not specifically illustrated, the back part 51 may be configured, for example, by stacking a plurality of plates, similarly to the flow path member 53. Regarding this point, the description of the flow path member 53 may be applied to the back part 51.
(4. Heat sinks)
[0089] The shape and dimensions of each heat sink 11 and flow path 13 are arbitrary. In the example in FIGs. 3 to 5, the heat sink 11 has a substantially rectangular plate-like shape. The rectangle of the heat sink 11 may be square or oblong (other than a square), and the longitudinal direction of the oblong may be either the D1 direction or the D3 direction (the former in the illustrated example).
[0090] FIG. 8 is a view of the heat sink 11 as seen from inside the housing 23. In this figure, an example of the flow path 13 is indicated by a dotted line, and the drive ICs 37 are also illustrated. In more detail, this figure illustrates the +D2 side heat sink 11, among the two heat sinks 11, but the -D2 side heat sink 11 is basically the same as that in FIG. 8.
[0091] The flow path 13 illustrated in FIG. 8 includes a central flow path 13a extending in the D1 direction and two end flow paths 13b extending in the D3 direction. The central flow path 13a penetrates through the heat sink 11 in the D1 direction, and both ends thereof are blocked by appropriate blocking members (see FIGs. 3 and 4; reference symbols are omitted). The two end flow paths 13b each extend from the upper surface of the heat sink 11 to the central flow path 13a, connecting one end or the other of the central flow path 13a to the space outside the heat sink 11. The coolant is supplied to the upper end of one end flow path 13b, flows through the one end flow path 13b, the central flow path 13a, and the other end flow path 13b in this order, and is ejected from the upper end of the other end flow path 13b.
[0092] Examples of the path of the flow path 13 other than the illustrated example are given below. For example, the flow path 13 may include multiple central flow paths 13a extending parallel to each other between two end flow paths 13b. Furthermore, the flow path 13 may include a meandering portion extending in the D1 direction while switching back and forth in the D3 direction, or a meandering portion extending in the D3 direction while switching back and forth in the D1 direction. The multiple central flow paths 13a or the meandering portion may extend over the entire heat sink 11, or may extend over a partial region (e.g., a region obtained by dividing the heat sink 11 into two or three equal parts in the D3 direction). As can be understood from the illustrated example and the other examples described above, the flow path 13 may be configured to locally cool the heat sink 11 or may be configured to cool the entire heat sink 11. For convenience, the description of the embodiments may be based on the illustrated example unless otherwise specified.
[0093] As illustrated in FIGs. 3 and 4, the upper opening of the end flow path 13b on the +D1 side of one heat sink 11 (see the position of the connecting part 31; the same applies below) and the upper opening of the end flow path 13b on the +D1 side of the other heat sink 11 are connected by the communication pipe 33. The coolant is supplied to the upper opening of the end flow path 13b on the -D1 side of one heat sink 11, flows sequentially through the flow path 13 of the one heat sink 11, the communication pipe 33, and the other heat sink 11, and is ejected from the upper opening of the end flow path 13b on the -D1 side of the other heat sink 11.
[0094] As illustrated in FIG. 8, when the heat sink 11 is viewed along a direction normal thereto, the multiple drive ICs 37 are arranged along the central flow path 13a so as to overlap the central flow path 13a. However, the two do not need to overlap. Furthermore, the -D1 side end of the -D1 side drive IC 37, among the multiple drive ICs 37, may be located on the +D1 side of the -D1 side end flow path 13b in terms of position in the D1 direction, or may overlap (the illustrated example), or may be located on the -D1 side of the -D1 side end flow path 13b. The same applies to the +D1 side end of the +D1 side drive IC 37.
[0095] The overlap between the drive ICs 37 and the central flow path 13a when viewed in the D2 direction may be at least a portion of the drive ICs 37 and a portion of the central flow path 13a, and the overlapping size may be arbitrary. For example, the length of the drive ICs 37 in the D3 direction may fit within the length of the central flow path 13a in the D3 direction, or conversely, the length of the central flow path 13a in the D3 direction may fit within the length of the drive ICs 37 in the D3 direction. The two may overlap each other perfectly in the D3 direction, or may overlap partially and extend beyond each other in the D3 direction. Furthermore, for example, at least half or at least two-thirds of the length of the drive ICs 37 in the D3 direction may overlap the central flow path 13a.
[0096] The position of the central flow path 13a in the D3 direction is arbitrary. For example, the central flow path13a is positioned toward the bottom within the heat sink 11. Specifically, the central flow path13a may be located in the lowest region when the height of the heat sink 11 (the length from the bottom surface to the top surface) is divided into two, three, or four equal parts. By positioning the central flow path13a toward the bottom, for example, in a configuration in which the drive ICs 37 overlap the central flow path 13a, the positions of the drive ICs 37 overlapping the central flow path13a can be made relatively lower, and this facilitates securing space in the upper region within the housing 23 (or, from another perspective, to reduce the height of the housing 23). On the other hand, the influence of the flow passage 13 on the temperature of the head body 9 is increased, and this increases the likelihood of the aforementioned drawback occurring. As a result, the usefulness of the heat insulating member 15 is increased.
[0097] The positions of the end flow paths 13b in the D1 direction are arbitrary. For example, the two end flow paths 13b are positioned on opposite sides in the D1 direction within the heat sink 11. Specifically, for example, the distance (shortest distance) between the end flow paths 13b and the side surfaces of the heat sink 11 extending in the D3 direction may be 1/10 or less of the length of the heat sink 11 in the D1 direction. By positioning the two end flow paths 13b on opposite sides, for example, the likelihood of coolant accumulating at both ends of the central flow path 13a is reduced. In addition, the drive ICs 37 are easily disposed at both ends so that as to not outwardly protrude beyond the end flow paths 13b in the D1 direction (toward the ends of the central flow path 13a). In other words, the entirety of the drive ICs 37 are easily disposed at both ends in regions where the likelihood of coolant accumulating is low.
[0098] The cross-sectional shape and dimensions of the flow path 13 are arbitrary. For example, the cross-sectional shape may be circular (as illustrated in FIG. 5) or rectangular. The cross-sectional shape and dimensions of the flow path 13 may be constant in the flow path direction, except for unique portions such as the ends (as in the illustrated example), or may not be constant. Furthermore, as can be understood from the above description of the overlap between the drive ICs 37 and the central flow path 13a, the diameter of the flow path 13 when viewed in a direction normal to the heat sink 11 (for example, the maximum length in the D3 direction of the central flow path 13a) may be smaller, equal to, or larger than the length of the drive ICs 37 in the D3 direction. The cross-sectional shapes and areas of the central flow path 13a and the end flow paths 13b may be the same, except for unique portions such as the ends, (the illustrated example) or different from each other.
[0099] The heat sink 11 may be formed as a single unit from the same material, or may be formed using a combination of a plurality of members. The manufacturing method thereof is also arbitrary.
[0100] For example, the heat sink 11 may be constructed by forming the flow path 13 in a metal plate by performing cutting. More specifically, for example, holes that will become the flow path 13 are drilled in the flow passage direction using a rotary tool (e.g., a drill). In addition, for example, the heat sink 11 may be cast by filling a metal material into the cavity of a mold that includes a core that will form the flow path 13. After the metal material has solidified, the core may be removed in the direction of the flow passage.
[0101] In the manufacturing method using cutting or casting as described above, the heat sink 11 can be integrally formed from the same material. The heat sink 11 in the illustrated example is assumed to be manufactured using the manufacturing method described above, with each portion (13a and 13b) of the flow path 13 having a linear shape, and both ends of the central flow path 13a reaching the side surfaces on the +D1 side and/or the -D1 side (both in the illustrated example) of the heat sink 11. These ends are then blocked.
[0102] Furthermore, for example, the heat sink 11 may be formed by adhering a second plate to a first plate including a recess (groove) that will become the flow path 13 in a main surface thereof (the surface on the +D2 side or the -D2 side) so as to close the recess. The first plate may be formed by forming the recess by performing cutting, or by filling a mold with a molding material. The heat sink 11 may also be formed by stacking multiple (three or more) plates like in the case of the front part 49.
[0103] In this manufacturing method in which two or more plates (members) are combined, there is a high degree of freedom in the shape of the flow path 13 (does not need to be linear). All of the two or more plates may be composed of metal (from another perspective, a material with high thermal conductivity), or only some of the plates (for example, the plate between the drive ICs 37 and the flow path 13) may be composed of metal.
[0104] The joining positions and joining method for the heat sinks 11 and the head cover 25 are arbitrary. For example, as illustrated in FIG. 5, the two heat sinks 11 may be fastened together with the head cover 25 sandwiched therebetween by bolts BT1 inserted through the two heat sinks 11 and nuts NT1 threaded onto the bolts BT1. Then, upon tightening, the two heat sinks 11 may clamp the head cover 25 therebetween, thereby joining the heat sinks 11 and the head cover 25 together.
[0105] In the above embodiment, as illustrated in FIG. 4, the head cover 25 may include flanges (reference symbols omitted) on the edges of the top and side surfaces that come into surface contact with the inner surfaces of the heat sinks 11. As illustrated in FIGs. 4 and 5, the flanges provided on the edges of the upper surface may include holes (reference symbols omitted) through which the bolts BT1 are inserted. Furthermore, the heat sink 11 may include recesses (reference symbols omitted) that accommodate at least a portion of the bolt heads of the bolts BT1 or the nuts NT1.
[0106] As indicated by the reference symbols in FIG. 8, the holes in the heat sinks 11 through which the bolts BT1 are inserted and/or the surrounding area thereof can be regarded as fixing portions 11a that fix the heat sinks 11 to the head cover 25. Alternatively, the upper edge portions of the heat sinks 11 may be regarded as the fixing portions 11a. As will be described later, the heat sinks 11 are joined to the heat insulating member 15 at fixing portions 11b (holes and/or the surrounding areas) located in lower portions of the heat sinks 11. Alternatively, lower edge portions of the heat sinks 11 may be regarded as the fixing portions 11b. Therefore, the drive ICs 37 can be said to be located between the fixing portions 11a and the fixing portions 11b.
(5. Heat insulating member)
(5.1. General points)
[0107] The heat insulating member 15 may be composed of any material, have any shape, size, etc., as long as the heat insulating member 15 is interposed between the head body 9 and the heat sinks 11 and can reduce the transfer of heat therebetween, in contrast to a configuration in which the head body 9 and the heat sinks 11 are in direct contact with each other. An example of the heat insulating member 15 illustrated in the drawings will now be described.
[0108] FIG. 9 is a perspective view of the heat insulating member 15. The entire heat insulating member 15 is formed in an integrated manner from the same material (e.g., resin), for example. The heat insulating member 15 is substantially frame-shaped (includes a frame-shaped portion 15a). A more specific shape of the frame-shaped portion 15a is a shape corresponding to the shape of the lower edge of the housing 23, and in the illustrated example, is a rectangular shape with the D1 direction as the longitudinal direction.
[0109] The frame-shaped portion 15a includes a frame-shaped base 15b and first ribs 15c standing upright on the base 15b. The base 15b is placed, for example, on the back surface of the head body 9. The first ribs 15c contribute, for example, to improving the strength of the frame-shaped portion 15a and/or joining the heat insulating member 15 and the heat sinks 11 to each other.
[0110] Unlike in the illustrated example, the frame-shaped portion 15a may not include the first ribs 15c. For example, the cross section of the frame-shaped portion 15a may be rectangular across substantially the entire periphery. This rectangle may be square or oblong (excluding square). The oblong may have a larger width (horizontal length) or height (vertical length). Furthermore, the frame-shaped portion 15a may have a partially interrupted shape instead of a shape that extends continuously over the entire periphery when viewed in the D3 direction. Furthermore, the heat insulating member 15 may have a shape that is difficult to regard as a frame shape.
(5.2. Base)
[0111] For example, the width of the base 15b is greater than the thickness (length in the D3 direction) of the base 15b (although this does not need to be the case). The ratio is arbitrary, but, for example, the width is at least twice the thickness. The width and/or thickness of the base 15b may or may not be constant along the entire periphery.
[0112] The base 15b may (but does not need to) include second ribs 15g that have a smaller height than the first ribs 15c. The second ribs 15g contribute to, for example, improving the strength of the base 15b. The positions of the second ribs 15g and the shape when viewed in the D3 direction are arbitrary. FIG. 9 illustrates, on the short sides of the base 15b, second ribs 15g extending in the D1 direction and second ribs 15g extending in the D2 direction.
[0113] Holes 15d may be formed in the short sides of the base 15b, through which screws (see FIG. 4, reference symbols omitted) for joining the heat insulating member 15 and the head body 9 to each other are inserted. The screws may be inserted into the holes 15d from above and threaded into female screws (see FIG. 4, reference symbols omitted) that open on the top surface of the back part 51. The holes 15d may be provided in the long sides in addition to or instead of the short sides of the heat insulating member 15.
[0114] An end portion of the pressing member 45 (more specifically, the portion of the support portion 45a facing the back surface of the head body 9) may overlap the short sides of the base 15b. The screws may be inserted through holes in the pressing member 45 (see FIG. 4; reference symbols omitted) in addition to the heat insulating member 15. That is, the heat insulating member 15 and the pressing member 45 may be fastened together. However, the pressing member 45 may be fixed only to the heat insulating member 15 without being fixed directly to the head body 9, or may be fixed to the head body 9 separately from the heat insulating member 15.
[0115] From another perspective, the pressing member 45 (more specifically, the portion of the support portion 45a facing the back surface of the head body 9) may be supported at both ends by the short sides of the heat insulating member 15. In other words, the pressing member 45 may be suspended above the upper surface of the head body 9 (strictly speaking, the upper surface heater 43 in the example of FIG. 4) except for at both ends (see also FIG. 5). This reduces the likelihood that the drive ICs 37 and the head body 9 will thermally affect each other via the pressing member 45, for example. However, the pressing member 45 may lay on the upper surface of the head body 9.
[0116] The lower surface of the base 15b may include a region that is flush along the entire periphery of the frame shape (this region may be the entire lower surface). The back surface of the head body 9 may have a flush region that faces the above-mentioned flush region of the base 15b over the entire periphery. In this case, for example, the seal between the heat insulating member 15 and the head body 9 is improved over the entire periphery of the frame-shaped portion 15a. However, the lower surface of the base 15b and/or the back surface of the head body 9 do not need to be flush. For example, there may be a gap between the lower surface of the base 15b and the back surface of the head body 9.
[0117] Although not specifically illustrated, an adhesive (e.g., a thermosetting resin) may be interposed between the lower surface of the base 15b and the back surface of the head body 9. This adhesive may contribute, for example, to joining the heat insulating member 15 and the head body 9 to each other and/or sealing the space therebetween. As can be understood from the above description, the heat insulating member 15 and the head body 9 may be fixed together with screws and an adhesive. However, the heat insulating member 15 and the head body 9 may also be fixed together with screws alone or with an adhesive alone. The space between the heat insulating member 15 and the head body 9 may be sealed with packing (e.g., an O-ring) interposed therebetween instead of or in addition to an adhesive.
(5.3. Ribs)
[0118] As illustrated in FIG. 9, the first ribs 15c extend, for example, along the long sides of the base 15b and protrude from the base 15b toward the +D3 side. The length through which the first ribs 15c extend along the long sides of the base 15b is arbitrary, and for example, each first rib 15c extends over 80% or more, 90% or more, or the entire length of the corresponding long side of the base 15b. The height of the first ribs 15c (the amount of protrusion from the base 15b) is, for example, greater than the thickness (in the D2 direction) of the first ribs 15c (although this does not need to be the case). The ratio is arbitrary, and for example, the height is at least twice the thickness.
[0119] The relationship between the height (D3 direction) and thickness (D2 direction) of the first ribs 15c and the width (direction from the inner periphery to the outer periphery) and thickness (D3 direction) of the base 15b is arbitrary as long as the thickness of the first ribs 15c is smaller than the width of the long side parts of the base 15b. The position of the first ribs 15c within the width of the long side parts of the base 15b is also arbitrary. In the illustrated example, each first rib 15c is located in a central region when the width of the corresponding long side part of the base 15b (ignoring the chamfered corners in the cross section) is divided into three equal parts. Unlike in the illustrated example, the first rib 15c may be provided on the edge of the inner or outer periphery of the base 15b. The thickness of first ribs 15c is, for example, 1/3 or 1/4 or less of the width of the long sides of the base 15b.
[0120] The first ribs 15c may include third ribs 15h on the wall surface facing the inside of the housing 23 or on the wall surface opposite thereto. The third ribs 15h contribute to, for example, improving the strength of the first ribs 15c. Furthermore, the third ribs 15h on the wall surface facing the inside of the frame-shaped portion 15a may contribute to positioning of components located on the inside. Similarly, the third ribs 15h on the wall surface facing the space outside the frame-shaped portion 15a may contribute to positioning of components located on the outside. FIG. 9 illustrates the third ribs 15h extending in the D3 direction on the inner wall surface.
[0121] The first ribs 15c include, for example, pockets 15e for accommodating nuts NT2 on a wall surface facing the inside of the frame-shaped portion 15a. The nuts NT2 contribute to joining the heat sinks 11 and the heat insulating member 15 together.
[0122] FIG. 10 is an enlarged view of region X in FIG. 5. FIG. 11 is a cross-sectional view similar to FIG. 10. However, FIG. 11 is at a slightly different position in the D1 direction from FIG. 10. Specifically, FIG. 11 is a cross-sectional view taken along line XI-XI in FIG. 9 (the position of a pocket 15e). In the following description, for convenience, the inside of frame-shaped portion 15a (or housing 23) may be simply referred to as the "inside", and the outside of frame-shaped portion 15a (or housing 23) may be simply referred to as the "outside". Furthermore, with regard to the heat sinks 11, first ribs 15c, etc., a surface facing inward may be referred to as an "inner surface", and a surface facing outward may be referred to as an "outer surface".
[0123] As illustrated in FIGs. 5, 10, and 11, the inner surface of the lower part of the heat sink 11 and the outer surface of the first rib 15c overlap each other. Then, as illustrated in FIG. 11, the bolt BT2 is inserted from the outside through a hole (reference symbol omitted) in the heat sink 11 and the hole 15f in the first rib 15c, and is screwed into the nut NT2. In this way, the heat sink 11 and the heat insulating member 15 are joined together. The numbers and positions of the bolts BT2 and nuts NT2 are arbitrary. As can be seen from the positions of the pockets 15e in FIG. 9, in the illustrated example, two sets of the bolt BT2 and the nut NT2 are provided on both sides in the D1 direction for one first rib 15c (one heat sink 11).
[0124] The pockets 15e, for example, contribute to facilitating the screwing operation. For example, the nuts NT2 can be placed near the first rib 15c in advance before various operations, including the screwing operation. The nuts NT2 are fitted into the pockets 15e, thereby preventing rotation. In other words, a robot or an operator does not need to hold the nuts NT2 to restrict rotation of the nuts NT2 during screwing. Furthermore, screwing can be carried out even when the space inside the heat sinks 11 is closed (for example, when the heat insulating member 15 is fixed to the head body 9 and the head cover 25 is fixed to the heat sinks 11). The specific shape and dimensions of the pockets 15e are arbitrary.
[0125] As illustrated in FIGs. 10 and 11, each heat sink 11 includes a recess 11c formed in the cross section thereof by cutting out a corner between the inner surface and the lower surface (also see FIG. 4). From another perspective, the portion of the heat sink 11 facing the first rib 15c is made thinner from the inside. This allows, for example, as illustrated in FIG. 11, the top of the first rib 15c to abut against the lower surface of the heat sink 11 inside the recess 11c, thereby positioning the heat sink 11 relative to the heat insulating member 15 in the D3 direction. Furthermore, for example, the position of the outer surface of the heat sink 11 can be shifted inward, thereby achieving a reduction in the size of the housing 23 in the D2 direction.
[0126] As can be understood by comparing FIGs. 10 and 11, the part of the first rib 15c at the position of the pocket 15e is slightly higher than the parts at other positions. Only the former part abuts against the lower surface of the heat sink 11 within the recess 11c. Unlike in the illustrated example, almost the entire first rib 15c may abut against the lower surface of the heat sink 11. Alternatively, the entire first rib 15c (including the part in the pocket 15e) may not abut against the lower surface of the heat sink 11. The first rib 15c may abut against the lower surface of the heat sink 11 at some positions excluding the positions of the pockets 15e.
[0127] Since the heat sink 11 is supported by the first rib 15c via the bolt BT2 and/or supported by the top of the first rib 15c, the lower surface of the heat sink 11 (excluding the recess 11c) may be (or may not be) suspended above the upper surface of the base 15b. That is, the lower surface of the heat sink 11 faces a part (base 15b) that supports the lower part of the first rib 15c across a gap 101. This gap 101 (gas (e.g., air) present in the gap 101) contributes to, for example, thermal insulation between the heat sink 11 and the heat insulating member 15. Unlike in the illustrated example, the portion that supports the lower part of the first rib 15c and faces the lower surface of the heat sink 11 across the gap 101 may be the head body 9 rather than the base 15b. For example, in the illustrated example, the part of the base 15b outside the first rib 15c may be omitted.
[0128] In an embodiment in which the recess 11c is provided, the outer surface of the heat sink 11 may be located outside (example in FIGS. 10 and 11), coincident with, or inside the outer surface of the heat insulating member 15 (base 15b) and/or the outer surface of the head body 9. When not coincident, the degree of difference in position is also arbitrary. The difference in position between the outer surface of the heat sink 11 and the outer surface of the heat insulating member 15 and/or the outer surface of the head body 9 may be, for example, 1/10 or less of the thickness of the heat sink 11 (including the case where there is no difference).
[0129] The various dimensions of the recess 11c are arbitrary. For example, the length of the recess 11c in the D1 direction is arbitrary as long as the length is equal to or greater than the length of the first rib 15c in the D1 direction (i.e., a length that allows the first rib 15c to be accommodated). For example, the length of the recess 11c in the D1 direction may be approximately the same as the length of the first rib 15c in the D1 direction (e.g., the former is greater than or equal to the latter and less than or equal to than 1.2 times the latter). Furthermore, for example, the length of the recess 11c in the D2 direction may be greater than or equal to 1/3 and less than or equal to 2/3 of the thickness of the heat sink 11 (approximately 1/2 in the illustrated example). Furthermore, the length of the recess 11c in the D3 direction may be smaller than, equal to, or greater than the height (length in the D3 direction) of the first rib 15c (the portion at the position of the pocket 15e or another position). In addition, in an embodiment in which the top of the first rib 15c abuts against the lower surface of the heat sink 11 within the recess 11c and forms the gap 101, the length of the recess 11c in the D3 direction is greater than the height of the abutting portion of the first rib 15c.
[0130] The outer surface of the first rib 15c is, for example, not provided with the third ribs 15h described above. Furthermore, no ribs are provided on the inner surface of the heat sink 11 within the recess 11c. Therefore, the outer surface of the first rib 15c and the inner surface of the heat sink 11 within the recess 11c are in surface contact with each other. In this case, for example, the sealing performance between the heat insulating member 15 and the heat sink 11 can be improved. However, ribs (protrusions as a broader concept) may be provided on the outer surface of the first rib 15c and/or the inner surface of the heat sink 11. In this case, for example, the contact area between the heat sink 11 and the heat insulating member 15 is reduced, thereby reducing the likelihood of heat transfer between the heat sink 11 and the heat insulating member 15.
[0131] Unlike in the illustrated example, the recess 11c may not be provided. From another perspective, for example, the entire thickness of the heat sink 11 may be located outside the first rib 15c. Furthermore, the heat sink 11 may be located inside the first rib 15c instead of outside the first rib 15c. In this case, the recess 11c may or may not be formed on the outer surface of the lower portion of the heat sink 11. As described above, the first rib 15c may be located at an outer edge of the base 15b. In this case, the recess 11c may not be formed and the entire thickness of the heat sink 11 may be located outside the first rib 15c, so that the lower surface of the heat sink 11 and the upper surface of the base 15b (and furthermore the back surface of the head body 9) do not face each other.
[0132] The pocket 15e does not have to be provided. Furthermore, the bolt BT2 and the nut NT2 may be positioned with the nut NT2 on the outside and the bolt BT2 on the inside, the opposite arrangement to that in the illustrated example. However, this would typically reduce workability. The nut NT2 may be unnecessary. For example, a bolt BT2 inserted into the heat sink 11 may be threaded into a female thread provided in the heat insulating member 15 (first rib 15c), or a bolt BT2 inserted into the heat insulating member 15 may be threaded into a female thread provided in the heat sink 11. However, using a nut NT2 composed of metal (and a bolt BT2 composed of metal) provides higher fastening reliability than forming a female thread in the heat insulating member 15 composed of resin.
[0133] The heat insulating member 15 and the heat sink 11 may be joined together using other methods instead of or in addition to the bolts BT2. For example, the two components may be fixed to each other using an adhesive (for example, a thermosetting resin).
(5.4.Materials)
[0134] The material of the heat insulating member 15 has a lower thermal conductivity than, for example, the materials of the head body 9 and the heat sinks 11 (either the entire head body 9 or the facing portions). This reduces the heat transfer between the head body 9 and the heat sinks 11 compared to an embodiment in which the head body 9 and the heat sinks 11 are in direct contact with each other.
[0135] For example, the back surface of the head body 9 and the lower surfaces of the heat sinks 11 may be composed of metal. On the other hand, the heat insulating member 15 may be composed of resin. Typically, the thermal conductivity of resin is lower than the thermal conductivity of metal.
[0136] The specific types of metal and resin in the above embodiments are also arbitrary. Examples are given below.
[0137] The material of the plates 63 of the front part 49 and the plates (not illustrated) of the back part 51 (the material of the back surface of the head body 9) is, for example, stainless steel. From another perspective, the thermal conductivity of the material is, for example, 10 W/m°C or more and 40 W/m°C or less.
[0138] The material of the heat sinks 11 is, for example, aluminum or an aluminum alloy. From another perspective, the thermal conductivity of the material is, for example, 200 W/m·°C or more and 300 W/m·°C or less. The description of the material of the heat sinks 11 (including the description below) may be applied to the material of the head cover 25.
[0139] The material of the heat insulating member 15 is, for example, PPS (polyphenylenesulfide) resin. From another perspective, the thermal conductivity of the material is, for example, 0.5 W/m·°C or more and 2 W/m·°C or less.
[0140] The thermal conductivity of typical resins is less than 0.5 W/m°C. Here, the specific type of resin for the heat insulating member 15 is selected so that the linear expansion coefficient of the heat insulating member 15 approaches the linear expansion coefficient of the material of the head body 9 and/or the heat sinks 11. As a result, the thermal conductivity of the heat insulating member 15 is high considering that the material is resin.
[0141] For example, the linear expansion coefficient of the material of the plates of the head body 9 is 0.5x10-6 or more and 2.0x10-6 or less (1/°C). The linear expansion coefficient of the material of the heat sinks 11 is 2.0x10-5 or more and 3.0x10-5 or less (1/°C). The linear expansion coefficient of the material of the heat insulating member 15 is 1.0x10-5 or more and 4.0x10-5 or less (1/°C).
(6. Other examples of heads)
[0142] FIG. 12 is a perspective view for describing a head 203 according to another example, and corresponds to FIG. 3. FIG. 13 is a cross-sectional view for describing the head 203, and corresponds to FIG. 11.
[0143] The head 203 differs from the head 3 only in that a sealing resin 103 (FIG. 13) is disposed therein. In FIG. 12, a region R1 where the sealing resin 103 is disposed (not the sealing resin 103 itself) is indicated by hatching. The sealing resin 103 is disposed from the exterior side so as to seal the boundary, visible from the exterior, formed by the heat sinks 11, the head cover 25, and the heat insulating member 15. The sealing resin 103 is also disposed in the holes that house the bolt heads of the bolts BT1 and BT2 and the nuts NT1 and NT2 (from another perspective, the through holes through which the bolts BT1 and BT2 are inserted). The sealing resin 103 contributes to improving the airtightness of the housing 23, for example.
[0144] As illustrated in FIG. 13, the sealing resin 103 is also disposed in the gap 101 between the lower surfaces of the heat sinks 11 and the upper surface of the base 15b. In the illustrated example, the sealing resin 103 fills the entire gap 101, and there is no space where gas exists. However, for example, the outer portion of the gap 101 may be filled with the sealing resin 103, leaving space inside the gap 101.
[0145] The material of the sealing resin 103 is arbitrary, and is, for example, a thermosetting resin. The thermal conductivity of the sealing resin 103 is, for example, lower than that of the plates of the heat sinks 11 and the head body 9. The thermal conductivity of the sealing resin 103 may be lower than, equal to, or higher than that of the heat insulating member 15. As described above, the material of the heat insulating member 15 may be selected to have a higher thermal conductivity than general resins, taking into account the linear expansion coefficient. In such a case, the thermal conductivity of the sealing resin 103 is likely to be lower than that of the heat insulating member 15.
(7. Experimental Examples)
[0146] As described in the overview of the embodiments, the heat sinks 11 including the flow paths 13 have an unintended cooling effect that affects the ink droplet ejection characteristics of the head body 9. An example of this is described below.
[0147] FIG. 14 is a diagram illustrating the image quality in printing using a head according to a comparative example. The head according to the comparative example basically differs from the head 3 only in that the head according to the comparative example does not include the heat insulating member 15. In other words, the lower surfaces of heat sinks 11 including the flow paths 13 are directly stacked on the back surface of head body 9. Note that the description regarding the arrangement of multiple ejection holes 7 in the head according to the comparative example described below may be applied to the head 3 (and 203) according to an embodiment.
[0148] The upper diagram in FIG. 14 is a planar perspective view of a portion of the ejection surface 5 of the head according to the comparative example. The multiple ejection holes 7, for example, form multiple rows (14 rows in the illustrated example) of ejection hole rows NR (only one row is labeled with a reference symbol). Each ejection hole row NR includes ejection holes 7 arranged in the D1 direction or in a direction inclined toward the D1 direction. When the multiple ejection hole rows NR are viewed in the D2 direction, the ejection holes 7 of each ejection hole row NR are disposed so as to be positioned between the ejection holes 7 of other ejection hole rows NR.
[0149] When printing is performed while moving the print paper P and the head relative to each other in the D2 direction, ink droplets from the multiple ejection hole rows NR can be made to land at the same position in the D2 direction on the print paper P by adjusting the ejection timing of ink droplets from the multiple ejection hole rows NR. At this time, since the ejection holes 7 of the multiple ejection hole rows NR are positioned at different positions in the D1 direction, an image is printed at a pitch that is smaller than the pitch of the ejection holes 7 within each ejection hole row NR.
[0150] The above-described printing can be achieved using various arrangement patterns of the multiple ejection holes 7. In the illustrated example, when the multiple ejection holes 7 are viewed in the D2 direction, the ejection holes 7 are arranged in order from the -D1 side in the following order: multiple consecutive rows (four rows) of ejection holes 7 on the +D2 side, multiple consecutive rows (six rows) of ejection holes 7 in the center in the D2 direction, and multiple consecutive rows (four rows) of ejection holes 7 on the -D2 side. Furthermore, this pattern repeats.
[0151] The above combination of three numbers as 4 rows, 6 rows, and 4 rows may be changed to other combinations of numbers. For example, each number may be any number greater than or equal to 1. Instead of three numbers, there may be one number, two numbers, or four or more numbers. The combination of numbers may vary within one head (the same pattern does not need to be repeated). The sum of the three numbers (total number of ejection hole rows NR) is arbitrary.
[0152] The middle and bottom parts of FIG. 14 are photographs illustrating the results of printing on printing paper P using the head of the comparative example. More specifically, in this example, there is an intention to draw a straight line parallel to the D1 direction. Note that the arrangement pattern of the ejection holes 7 in the top part of FIG. 14 is for the sake of convenience of explanation, and does not strictly match the arrangement pattern of the ejection holes 7 of the head that performed the printing illustrated in the middle and bottom photographs in FIG 14 (although they do generally match).
[0153] The photograph in the middle part of FIG. 14 illustrates the case where no coolant was flowing through the flow paths 13 of the heat sinks 11. The photograph in the bottom of FIG. 14 illustrates the case where a coolant was flowing through the flow paths 13 of the heat sinks 11. The coolant was water at 15°C. The printing paper P moved toward the +D2 side relative to the head.
[0154] When the coolant is not flowing, the multiple dots formed by the ink droplets ejected from the ejection holes 7 are aligned roughly in a line in the D1 direction. On the other hand, when the coolant is flowing, the dots formed by the ink droplets ejected from the ejection holes 7 located at the ends on the +D2 and -D2 sides are shifted toward the -D2 side relative to the other dots. The reason for this is as follows.
[0155] As is clear from FIGs. 3 to 5, when the heat insulating member 15 is not provided, the lower surfaces of the heat sinks 11 overlap the vicinity of the +D2 and -D2 edges of the rear surface of the head body 9. Furthermore, as illustrated in FIGs. 5 and 6, the back part 51 that forms the rear surface of the head body 9 overlaps the vicinity of the outer edge of the rear surface of the flow path member 53 that forms the ejection surface 5. Therefore, the flow path member 53 is more susceptible to the cooling action of the heat sinks 11 near the outer edge. As a result, an imbalance occurs in the temperature distribution in the flow path member 53 such that the temperature decreases toward the outer edge.
[0156] As a result of the above, the temperature of the ink in the flow path member 53 decreases toward the outer edge of the flow path member 53, and therefore the viscosity increases. As a result, ink droplets ejected from the ejection holes 7 located at the outer edge of the flow path member 53 experience a delay in ejection timing and/or a decrease in ejection speed compared to the other ejection holes 7. As a result, as illustrated in the photograph in the lower part of FIG. 14, the dots formed by the ejection hole rows NR located at the ends on the -D2 side and +D2 side are shifted in the opposite direction to the transport direction of the printing paper P.
[0157] As exemplified in FIG. 6, this shift is likely to be large when multiple common flow paths 59 extending parallel to one another extend in the D1 direction or in a direction inclined toward the D1 direction. This is because we do not expect that the flow of ink in the D2 direction will alleviate the imbalance in the temperature distribution in the D2 direction. Of course, even if the common flow paths 59 extend in the D2 direction, there is not necessarily a flow of ink large enough to alleviate the imbalance in the temperature distribution, so the shift can be large.
[0158] In the above description, we focused on the imbalance in the temperature distribution in the D2 direction in the flow path member 53. However, in the flow path member 53, an imbalance in the temperature distribution in the D1 direction also occurs. The reason for this is, for example, that the back part 51 overlaps the outer periphery of the back surface of the flow path member 53 (i.e., overlaps the ends on the -D1 side and +D1 side). This also causes dot misalignment. However, in experiments carried out by the inventors, the influence of an imbalance in the temperature distribution in the D1 direction was smaller than the influence of an imbalance in the temperature distribution in the D2 direction.
[0159] By providing the heat insulating member 15 as in the embodiments, the amount of dot misalignment described above can be reduced. For example, when the intention is to print a straight line parallel to the D1 direction, the amount of misalignment is defined as the distance between a straight line (virtual line) parallel to the D1 direction that contacts the dot furthest to the +D2 side from the +D2 side, and a straight line (virtual line) parallel to the D1 direction that contacts the dot furthest to the -D2 side from the -D2 side. In the experiments carried out by the inventors, when the heat insulating member 15 was provided, the amount of misalignment could be reduced by about 7 µm compared to when the heat insulating member 15 was not provided (when the coolant was water at 15°C).
(8. Summary of embodiments)
[0160] Hereinafter, some of the configurations of the recording device and head according to the embodiments will be extracted and their effects will be described. In the following, the reference symbols of the head 3 will be mainly used, but the same or similar applies to the head 203.
[0161] A liquid ejection head (head 3) according to an embodiment includes the head body 9, the heat sinks 11, and the heat insulating member 15. The head body 9 includes the ejection holes 7. Each heat sink 11 includes the flow path 13. The heat insulating member 15 is interposed between the head body 9 and the heat sinks 11. A recording device (printer 1) according to an embodiment includes such a head 3.
[0162] Therefore, for example, as described in the overview of the embodiments and with reference to FIG. 14, the likelihood that the unintended cooling action of the heat sinks 11 will affect the temperature of the head body 9 is reduced. As a result, for example, the likelihood that the image quality of a printed image will be degraded is reduced.
[0163] The head 3 may further include the drive ICs 37 located on the surfaces of the heat sinks 11.
[0164] In this case, for example, the heat sinks 11 including the flow paths 13 can quickly cool the drive ICs 37. As a result, for example, the drive ICs 37 can be made to perform a high-load operation that increases the temperature of the drive ICs 37. For example, printing can be performed at a high frequency, thereby improving the printing speed.
[0165] The heat insulating member 15 may include the frame-shaped portion 15a that overlaps the back surface of the head body 9 on the opposite side from the ejection holes 7 and has a frame shape when viewed in a direction normal to the back surface. The frame-shaped portion 15a may include the first ribs 15c (an example of a rib) that protrudes along the normal direction (for example, parallel to the normal direction) and extends along the peripheral direction of the frame shape (for an appropriate length of one revolution or less).
[0166] In this case, for example, the contact area between the heat insulating member 15 and the head body 9 can be reduced by making the heat insulating member 15 frame-shaped. As a result, the likelihood of heat being transferred between the heat sink 11 and the head body 9 via the heat insulating member 15 is reduced. In other words, the heat insulating effect is improved. Furthermore, as a result of the heat insulating member 15 including the first ribs 15c, rigidity can be ensured even when the heat insulating member 15 is frame-shaped.
[0167] The heat insulating member 15 may include the first ribs 15c (an example of a rib) that protrudes from a portion (base 15b) that overlaps the back surface of the head body 9 on the opposite side from the ejection surface toward the side in which the back surface faces. The heat sinks 11 may be joined to the heat insulating member 15 by joining the heat sinks 11 to a wall surface of the first ribs 15c.
[0168] In this case, for example, heat from the heat sinks 11 is transmitted horizontally between the heat sinks 11 and the first ribs 15c, then downward through the first ribs 15c, and then to the back surface of the head body 9. This heat path is longer than the heat path along which heat from the heat sinks 11 is transmitted to the base 15b in a configuration in which the heat sinks 11 are joined to the upper surface of the base 15b (this configuration may also be included in the present disclosure). The formation of such a path improves the heat insulating effect.
[0169] The lower surfaces of the heat sinks 11 and the portion supporting the first ribs 15c (the base 15b in the illustrated example) may face each other with the gap 101 therebetween.
[0170] In this case, for example, the gap 101 insulates the heat sinks 11 from the base 15b, improving the heat insulating effect. In other words, a thermal shortcut from the lower surfaces of the heat sinks 11 to the upper surface of the base 15b is unlikely to occur.
[0172] In this case, for example, the sealing resin 103 insulates the area between the lower surfaces of the heat sinks 11 and the heat insulating member 15, thereby improving the heat insulating effect. In addition, by applying the sealing resin, the sealing performance of the head 203 is also improved.
[0173] The head 3 may further include the head cover 25 that covers the heat insulating member 15 and is joined to the heat sinks 11.
[0174] In this case, for example, heat from the heat sinks 11 can escape to the head cover 25. As a result, the heat from the heat sinks 11 is less likely to be transmitted to the heat insulating member 15, and furthermore, is less likely to be transmitted to the head body 9 via the heat insulating member 15. As a result, the thermal insulation between the heat sinks 11 and the head body 9 is improved.
[0175] The drive ICs 37 may be located between the fixing portions 11a fixing the heat sinks 11 to the head cover 25 and the fixing portions 11b fixing the heat sinks 11 to the heat insulating member 15.
[0176] In this case, for example, the heat sinks 11 can be fixed to the head cover 25 and the heat insulating member 15 on both sides of the drive ICs 37 in a predetermined direction (D3 direction in the illustrated example). This improves the reliability of the positioning of the heat sinks 11 relative to the drives IC 37, and in turn improves the adhesion between the drive ICs 37 and the heat sinks 11. As a result, the performance of dissipating heat from the drive ICs 37 is improved.
[0177] When viewed in a direction normal to the heat sinks 11, the flow paths 13 and the drive ICs 37 may overlap (at least partially).
[0178] In this case, for example, the three-dimensional distance between the flow paths 13 and the drive ICs 37 is short, so that heat can be efficiently exchanged between the coolant flowing through the flow paths 13 and the drive ICs 37. In other words, heat can be efficiently dissipated from the drive ICs 37.
[0179] The head 3 may further include the pressing member 45. The pressing member 45 may be located on the opposite side of the head body 9 from the ejection holes 7, and may press the drive ICs 37 against the heat sinks 11. In addition, both ends of the part of the pressing member 45 that faces the head body 9 may be supported by the heat insulating member 15, and the portion between the ends may be suspended above the head body 9.
[0180] In this case, for example, by pressing the drive ICs 37 against the heat sinks 11, heat can be effectively dissipated from the drive ICs 37 to the heat sinks 11. Furthermore, since the pressing member 45 is suspended from the side of the head body 9, the likelihood of heat being transferred from the drive ICs 37 to the head body 9 via the pressing member 45 can be reduced. Because the heat insulating member 15 also serves as a member for suspending the pressing member 45, the number of components can be reduced.
[0181] The head 3 may further include drive ICs 37 located on the opposite side of the head body 9 from the ejection holes 7, and the housing 23 that covers the head body 9 from the opposite side from the ejection holes 7 and houses the drive ICs 37. Two heat sinks 11 may face each other and form two side surfaces of the housing 23.
[0182] That is, the flow paths 13 may be provided in the housing 23. In this case, for example, by providing the flow paths 13 in the housing 23, the influence of the temperature outside the housing 23 on the temperature inside the housing 23 can be reduced by controlling the temperature using the flow paths 13. As a result, for example, as well as dissipation of heat from the drive ICs 37, the temperature of the head body 9 or other electronic components is more easily maintained constant, and consequently the operation of the head 3 is stabilized.
[0184] That is, the coolant flowing through the flow paths 13 and the liquid (ink) supplied to the ejection holes 7 may be separate from each other. In this case, for example, a coolant with a lower temperature than the ink can be used, facilitating dissipation of heat from the drive ICs 37. Furthermore, when ink is used as the coolant, changes in the amount of heat transferred from the drive ICs 37 to the ink will change the temperature (and therefore the viscosity) of the ink, which will change the ejection characteristics of the ink droplets, but the likelihood of such a problem occurring is low.
[0185] In an embodiment described above, the printer 1 is an example of a recording device. The heads 3 and 203 are each an example of a liquid ejection head.
[0186] The technology according to the present disclosure is not limited to the above-described embodiments and may be implemented in various forms.
[0187] The recording device may be a plotter. The recording device may be a handheld printer that is held and moved entirely by a user's hand and moves relative to a recording medium. The recording device may be one in which the recording medium and the head are moved relative to each other by moving the head using a robot or the like.
[0188] The recording medium is not limited to paper. The recording medium may be, for example, cloth, wood, tile, a printed wiring board (more specifically, an insulating layer on which a conductive pattern is printed), or a car body.
[0189] The head may be used for purposes other than a recording device. For example, the head may be used in the manufacture of chemicals. Specifically, the head may eject a predetermined amount of a liquid chemical or a liquid containing a chemical toward a reaction vessel or the like.
[0190] As can be understood from the examples of the recording medium and the like given above, the liquid is not limited to ink. For example, the liquid may be paint or a conductive material to be printed onto a printed wiring board.
[0191] A pressure applying unit for applying pressure to a flow path (liquid) to eject a liquid is not limited to a piezoelectric type. For example, the pressure applying unit may be a unit that applies pressure to a liquid by heating the liquid to generate bubbles (thermal type pressure applying unit).
[0192] The flow path member is not limited to one formed by stacking metal or resin plates. For example, the flow path member may be formed using MEMS (micro electro mechanical systems). The MEMS may include not only the flow path member but also a pressure applying unit.
[0193] From the present disclosure, an invention may be extracted that does not require the head to include a heat sink, the head to include a heat insulating member, and/or the heat sink to include a flow path.
REFERENCE SIGNS
1. A liquid ejection head comprising:
a head body including an ejection hole;
a heat sink including a flow path; and
a heat insulating member interposed between the head body and the heat sink.
2. The liquid ejection head according to claim 1, further comprising:
a drive IC located on a surface of the heat sink.
a drive IC located on a surface of the heat sink.
3. The liquid ejection head according to claim 1 or 2,
wherein the heat insulating member includes a frame-shaped portion that overlaps a rear surface of the head body on an opposite side from the ejection hole and has a frame shape when viewed in a normal direction of the rear surface, and
the frame-shaped portion includes a rib that protrudes in the normal direction and extends along a peripheral direction of the frame shape.
4. The liquid ejection head according to any one of claims 1 to 3,
wherein the heat insulating member includes a rib that protrudes from a portion overlapping a rear surface of the head body, on an opposite side from the ejection hole, toward a side that the rear surface faces, and
the heat sink is joined to the heat insulating member by being joined to a wall surface of the rib.
5. The liquid ejection head according to claim 4,
wherein a lower surface of the heat sink and the portion supporting the rib face each other with a gap therebetween.
wherein a lower surface of the heat sink and the portion supporting the rib face each other with a gap therebetween.
6. The liquid ejection head according to claim 5,
wherein the gap contains a sealing resin.
wherein the gap contains a sealing resin.
7. The liquid ejection head according to any one of claims 1 to 6, further comprising:
a head cover that covers the heat insulating member and is joined to the heat sink.
a head cover that covers the heat insulating member and is joined to the heat sink.
8. The liquid ejection head according to claim 7, further comprising:
a drive IC located on a surface of the heat sink,
wherein the drive IC is located between a portion of the heat sink to which the head cover is fixed and a portion of the heat sink to which the heat insulating member is fixed.
9. The liquid ejection head according to claim 8,
wherein the flow path and the drive IC overlap when viewed in a normal direction of the heat sink.
wherein the flow path and the drive IC overlap when viewed in a normal direction of the heat sink.
10. The liquid ejection head according to claim 2 or any one of claims 3 to 9 that directly
or indirectly cites claim 2, further comprising:
a pressing member that is located on an opposite side of the head body from the ejection hole and presses the drive IC against the heat sink,
wherein both ends of a part of the pressing member that faces the head body are supported by the heat insulating member, and a portion between the both ends is spaced apart from the head body.
11. The liquid ejection head according to any one of claims 1 to 10, further comprising:
a drive IC located on an opposite side of the head body from the ejection hole; and
a housing that covers the head body from an opposite side from the ejection hole and accommodates the drive IC,
wherein two of the heat sinks face each other and constitute two side surfaces of the housing.
12. The liquid ejection head according to any one of claims 1 to 11,
wherein the flow path does not communicate with the ejection hole.
wherein the flow path does not communicate with the ejection hole.
13. A recording device comprising:
the liquid ejection head according to any one of claims 1 to 12.
the liquid ejection head according to any one of claims 1 to 12.
REFERENCES CITED IN THE DESCRIPTION
This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.
Patent documents cited in the description