FIELD
[0001] Embodiments described herein relate generally to a thermal head cartridge and a liquid
ejection device.
BACKGROUND
[0002] In the related art, a liquid ejection device including a liquid ejection head has
been known. A thermal head cartridge which is a thermal type liquid ejection head
is known.
[0003] As an ink used for such a liquid ejection head, an ink encapsulated using a reversible
thermochromic composition that discolors or decolorizes by heat is also known.
[0004] Such a liquid ejection head includes a common liquid flow path for supplying a liquid
to a nozzle. However, since the structural member for maintaining the shape of the
liquid ejection head is provided in the common liquid flow path, there is a problem
that heat accumulates in the ink in the common liquid flow path. For example, if the
temperature of the ink rises in the common liquid flow path, if the ink contains a
heat-decoloring type reversible thermochromic composition, when using a thermal head
cartridge, there is a risk of causing the ink to decolorize due to heat.
SUMMARY
[0005] An objective to be achieved by the present disclosure is to provide a thermal head
cartridge and a liquid ejection device capable of minimizing the accumulation of heat
in a common liquid flow path.
[0006] In general, according to one embodiment, a cartridge includes a case, a structural
member, a nozzle plate, and a common liquid flow path. The structural member is provided
in the case and maintains the shape of the case. The nozzle plate is provided in the
case and ejects a liquid. The common liquid flow path is formed in the case and the
structural member, and is continuous with the nozzle plate. The common liquid flow
path is wider in the structural member than in the case.
[0007] According to another embodiment, a plurality of the structural members are provided.
[0008] According to another embodiment, the thermal head cartridge further comprises a storage
body that contains the liquid and to which the case is connected.
[0009] According to another embodiment, the thermal head cartridge further comprises a filter
that is provided between the storage body and the case.
[0010] According to another embodiment, the thermal head cartridge further comprises a filter
holding frame that is provided in the storage body, which covers the periphery of
the common liquid flow path and holds the filter.
[0011] According to another embodiment, the liquid is an ink that discolors or decolorizes
by heat.
[0012] The present invention further relates to a liquid ejection device comprising the
above-mentioned thermal head cartridge and a support mechanism that supports a recording
medium that ejects the liquid.
DESCRIPTION OF THE DRAWINGS
[0013]
FIG. 1 is a perspective view schematically illustrating a configuration of a thermal
head cartridge according to an embodiment;
FIG. 2 is a cross-sectional view schematically illustrating a configuration of the
thermal head cartridge;
FIG. 3 is a plan view schematically illustrating a main configuration of a case of
the thermal head cartridge;
FIG. 4 is a perspective view schematically illustrating the main configuration of
the case according to the embodiment;
FIG. 5 is a cross-sectional view schematically illustrating a configuration of a nozzle
plate of the thermal head cartridge;
FIG. 6 is a cross-sectional view illustrating a configuration of the nozzle plate
in a cross section taken along the line VI-VI in FIG. 5; and
FIG. 7 is a perspective view schematically illustrating an example of a liquid ejection
device using the thermal head cartridge.
DETAILED DESCRIPTION
[0014] Hereinafter, a thermal head cartridge 1 and a liquid ejection device 2 according
to an embodiment will be described with reference to FIGS. 1 to 7. FIG. 1 is a perspective
view schematically illustrating a configuration of the thermal head cartridge 1 according
to the embodiment. FIG. 2 is a cross-sectional view schematically illustrating the
configuration of the thermal head cartridge 1. FIG. 3 is a plan view illustrating
a configuration inside a second case 112 as a main configuration of a case 11 of the
thermal head cartridge 1, and FIG. 4 is a perspective view schematically illustrating
a configuration inside the second case 112. FIGS. 5 and 6 are cross-sectional views
schematically illustrating a configuration of a nozzle plate 16 used in the thermal
head cartridge 1, and FIG. 6 is a cross-sectional view taken along the line VI-VI
in FIG. 5. For the sake of description in each drawing, the configuration is illustrated
enlarged, reduced or omitted as appropriate.
[0015] The thermal head cartridge 1 is, for example, a liquid ejection head provided in
the liquid ejection device 2 such as a recording device illustrated in FIG. 7. In
the present embodiment, the liquid is, for example, ink. That is, the thermal head
cartridge 1 is a thermal type inkjet head in which ink in a pressure chamber is heated
by a heater to generate bubbles and eject ink.
[0016] In the present embodiment, the ink as a liquid is, for example, a thermochromic ink
containing a reversible thermochromic composition that changes color by heat. Here,
the thermochromic ink includes not only a discoloring ink that changes color to a
different color by heat, but also a decolorizing ink that decolorizes by heat and
a color-developing ink that produces color by heat. Decolorization includes the case
of changing from a specific color to a transparent color.
[0017] The thermochromic ink contains, for example, a color-developing organic compound
as a thermochromic composition, an electron-accepting compound, and a reaction medium
that determines the temperature at which a color reaction occurs. The thermochromic
ink is a reversible thermochromic microcapsule pigment in which such a thermochromic
composition is encapsulated in microcapsules.
[0018] As illustrated in FIGS. 1 and 2, the thermal head cartridge 1 includes a case 11,
a lid 12, a storage body 13, a filter 14, a circuit board 15, and the nozzle plate
16. The thermal head cartridge 1 is used, for example, in a posture in which the lid
12 is disposed on the upper side and the nozzle plate 16 is disposed on the lower
side.
[0019] The case 11 includes a first case 111 that houses the storage body 13 and the filter
14, the second case 112, a filter holding frame 113, and a single or a plurality of
structural members 114. In the case 11, for example, a common ink flow path (common
liquid flow path) 115 is formed in the second case 112. The case 11 is molded from,
for example, a resin material.
[0020] The first case 111 is formed in the shape of a bottomed rectangular box formed long
in one direction, and the upper portion is open. For example, the first case 111 includes
two pairs of side walls 1111 formed in a rectangular tubular shape and a bottom wall
1112 formed at one ends of the two pairs of side walls 1111. The upper opening of
the first case 111 formed by the other ends of the two pairs of side walls 1111 is
closed by the lid 12. The first case 111 houses the storage body 13 inside. The second
case 112 is integrally formed at the bottom of the first case 111 on one end side
in the longitudinal direction.
[0021] The second case 112 is provided on the bottom wall 1112 of the first case 111, and
forms a space continuous with the inside of the first case 111. For example, the second
case 112 includes two pairs of side walls 1121 and a lower wall 1122 formed at one
ends of the two pairs of side walls 1121. The two pairs of side walls 1121 are integrally
formed with the bottom wall 1112 of the first case 111. The lower wall 1122 includes
a slit 1123 in which the nozzle plate 16 is provided. The slit 1123 is, for example,
a unidirectionally long rectangular opening formed in the lower wall 1122. The three
adjacent side walls 1121 form a side wall integrally formed with the three adjacent
side walls 1111 of the first case 111.
[0022] The filter holding frame 113 is formed in a tubular shape, and as a specific example,
a rectangular tubular shape. The filter holding frame 113 is provided in the second
case 112, for example, and is integrally formed with the lower wall 1122. The filter
holding frame 113 holds the filter 14 at the end (upper end) opposite to the lower
wall 1122. The filter holding frame 113 is disposed around the slit 1123 formed in
the lower wall 1122.
[0023] The structural member 114 is a reinforcing member that reinforces a part of the case
11. The number of structural members 114 is appropriately set according to the strength
required for the case 11, the material of the case 11, the shape of the case 11, and
the like. In the present embodiment, an example in which three structural members
114 are provided is illustrated in FIGS. 2 and 3.
[0024] The structural members 114 are provided, for example, over the second case 112 and
the filter holding frame 113. The structural member 114 maintains the shapes of the
second case 112 and the filter holding frame 113 by reinforcing the strength of the
second case 112 and the filter holding frame 113.
[0025] For example, the second case 112 and the filter holding frame 113 are formed long
in the same direction as the longitudinal direction of the first case 111, and the
structural member 114 extends along the lateral direction orthogonal to the longitudinal
direction of the second case 112 and the filter holding frame 113. The structural
member 114 includes a notch 1141 at a portion facing the slit 1123 formed in the lower
wall 1122 in the filter holding frame 113 of the second case 112. The notch 1141 is
an opening formed in a portion of the structural member 114 facing the slit 1123.
The width of the notch 1141 in the extending direction of the structural member 114
is, for example, larger than the width of the slit 1123. The notch 1141 has, for example,
a U-shape, a rectangular shape, a dome shape, or the like.
[0026] Here, the lateral direction is a direction along the surface direction of the lower
wall 1122 and a direction orthogonal to the longitudinal direction of the second case
112 and the filter holding frame 113. The lateral direction is a direction orthogonal
to the longitudinal direction of the slit 1123, and is an extension direction of the
structural member 114.
[0027] The width of the slit 1123 in the lateral direction is W1, and the width of the notch
1141 is W2. The width W1 of the slit 1123 is smaller than the width W2 of the notch
1141.
[0028] The common ink flow path 115 is a space in the filter holding frame 113, and is formed
by the slit 1123 of the lower wall 1122 of the second case 112 and the notch 1141
of the structural member 114. The common ink flow path 115 forms an ink flow path
from the filter 14 to the nozzle plate 16. Specifically, in the common ink flow path
115, the slit 1123 is continuous with the nozzle plate 16.
[0029] The width W1 of the slit 1123 is smaller than the width W2 of the notch 1141 and
the width of the filter holding frame 113 in the lateral direction. Therefore, the
width W2 in the structural member 114 of the common ink flow path 115 is wider than
the width W1 in the lower wall 1122 of the second case 112.
[0030] The lid 12 closes the opening of the case 11. The lid 12 is integrally fixed to the
case 11 by, for example, an adhesive or welding.
[0031] The storage body 13 stores the liquid. For example, the storage body 13 is a sponge
body such as a sponge capable of storing a liquid. The storage body 13 may be a tank
for storing the liquid. If the storage body 13 is a tank, the first case 111 may form
the storage body 13.
[0032] The filter 14 is held on the filter holding frame 113. The filter 14 is provided
between the storage body 13 and the filter holding frame 113 of the second case 112.
The filter 14 supplies the liquid stored in the storage body 13 to the common ink
flow path 115 in the filter holding frame 113.
[0033] The circuit board 15 is, for example, a flexible board. The circuit board 15 is provided,
for example, over the side walls 1111 and 1121 of one of the first case 111 and the
second case 112, and the lower wall 1122 of the second case 112. For example, a wiring
pattern and a terminal portion 151 are mounted on the circuit board 15. The circuit
board 15 is mounted with the nozzle plate 16 connected to the pattern wiring.
[0034] As illustrated in FIG. 4, the nozzle plate 16 is provided, for example, on the lower
surface of the second case 112. The nozzle plate 16 is disposed to face the slit 1123
of the second case 112. The nozzle plate 16 is connected to the common ink flow path
115. As illustrated in FIGS. 5 and 6, the nozzle plate 16 includes, for example, a
plurality of nozzle holes 161, a plurality of heaters 162, and a plurality of pillars
163. The nozzle plate 16 includes a plurality of pressure chambers 164 formed between
the nozzle holes 161 and the heaters 162. The nozzle plate 16 is provided to face
the slit 1123 of the second case 112, and is fluidly connected to the common ink flow
path 115.
[0035] The nozzle hole 161 is a hole for injecting a liquid. The plurality of nozzle holes
161 are disposed along, for example, the slit 1123 formed in the lower wall 1122 of
the second case 112. For example, the nozzle plate 16 is provided with two rows of
nozzles formed by the plurality of nozzle holes 161.
[0036] The heaters 162 are provided to face the plurality of nozzle holes 161. The heater
162 heats the ink existing in the pressure chamber 164 between the heater 162 and
the nozzle hole 161 to generate air bubbles. The heater 162 ejects ink from the nozzle
hole 161 by the generated air bubbles.
[0037] The pillars 163 are provided to face the plurality of pressure chambers 164 between
the nozzle holes 161 and the heaters 162. The pillar 163 removes air bubbles in the
pressure chamber 164 between the nozzle hole 161 and the heater 162. For example,
the pillar 163 is provided to face the pressure chamber 164 between the nozzle hole
161 and the heater 162.
[0038] For example, a maximum width W3 between the heaters 162 disposed in the lateral direction
of the nozzle plate 16 is smaller than the width W2 of the notch 1141. More preferably,
a width W4 in the lateral direction between the side surfaces of the pressure chambers
164 arranged in the lateral direction is smaller than the width W2 of the notch 1141.
[0039] Next, an example of the liquid ejection device 2 in which such a thermal head cartridge
1 is used will be described with reference to FIG. 7. The liquid ejection device 2
includes a plurality of thermal head cartridges 1, a head support mechanism 21, a
medium support mechanism 22, and a control unit 23.
[0040] The plurality of thermal head cartridges 1 eject, for example, a plurality of different
inks. The plurality of thermal head cartridges 1 ejects, for example, a thermochromic
ink and inks of a plurality of colors, such as cyan ink, magenta ink, yellow ink,
black ink, and white ink. The characteristics and colors of the ink used for the thermal
head cartridge 1 are not limited. Instead of the ink of each color, a transparent
glossy ink may be used, or all the thermal head cartridges 1 may be configured to
eject ink that discolors, develops color, and decolorizes when irradiated with heat
or ultraviolet rays. The plurality of thermal head cartridges 1 have the same configuration,
although the inks used therein are different from each other, for example.
[0041] The head support mechanism 21 movably supports the thermal head cartridge 1. For
example, the head support mechanism 21 includes a support member 211 for disposing
the plurality of thermal head cartridges 1 in parallel in a predetermined direction,
and a guide member 212 for moving the support member 211.
[0042] The support member 211 moves back and forth in one direction by, for example, the
guide member 212. The guide member 212 is a rail, a guide bar, a belt, or the like
that conveys the support member 211 so that the support member 211 moves back and
forth. The head support mechanism 21 includes a drive source such as a motor for conveying
the support member 211.
[0043] The medium support mechanism 22 movably supports a recording medium S. For example,
the medium support mechanism 22 includes a platen roller 221, a belt, a motor for
driving the platen roller 221, and the like, as appropriate, supports sheets of paper
as the recording medium S, and moves the sheets along a predetermined transport path.
[0044] The control unit 23 includes, for example, a processor 231, a drive circuit 232 for
driving each element, a storage unit 233 that stores various data, and a communication
interface 234 for external communication.
[0045] The processor 231 corresponds to the central part of the control unit 23. The processor
231 controls each part in order to realize various functions of the liquid ejection
device 2 according to the operating system and application programs.
[0046] The circuit board 15 provided in the thermal head cartridge 1 is connected to the
processor 231. For example, the processor 231 has a function of ejecting ink from
the nozzle hole 161 by controlling the operation of the heater 162 provided on the
nozzle plate 16 via the circuit board 15.
[0047] The drive circuit 232 generates a drive voltage to be applied to the corresponding
heater 162 based on image data, for example, according to the command of the processor
231.
[0048] The storage unit 233 includes, for example, a program memory or RAM. The storage
unit 233 stores application programs and various setting values. The storage unit
233 stores, for example, data such as image data, various setting values such as a
voltage value applied to the heater 162, and the like.
[0049] The communication interface 234 receives various information such as a user's input
command, a command from an external terminal, data, and a program.
[0050] If the processor 231 of the liquid ejection device 2 according to the present embodiment
detects, for example, a printing start command from the outside, the processor 231
controls each configuration as a printing operation. As a specific example, the processor
231 controls the medium support mechanism 22 to convey the recording medium S based
on the image data stored in the storage unit 233. The processor 231 controls the head
support mechanism 21 for a back-and-forth motion with respect to the recording medium
S, and conveys the thermal head cartridge 1 to the ink ejection position as illustrated
by the arrows in FIG. 7. Then, the processor 231 controls the heater 162 so that ink
is ejected to the recording medium S from any nozzle hole 161. The processor 231 forms
an image on the recording medium S by such control.
[0051] According to the liquid ejection device 2 and the thermal head cartridge 1 of the
present embodiment, the structural member 114 that reinforces the second case 112
and the filter holding frame 113 includes the notch 1141 at a portion facing the slit
1123 of the second case 112. The width W2 of the notch 1141 is larger than the width
W1 of the slit 1123. As a result, the slit 1123 is opened to the space inside the
filter holding frame 113 even at a portion facing the structural member 114. Therefore,
it is possible to prevent the slit 1123 from being blocked by the structural member
114 and heat from being trapped, and to prevent the accumulation of heat in the common
ink flow path 115.
[0052] The width W2 of the notch 1141 is preferably larger than the maximum width W3 between
the heaters 162 arranged in the lateral direction, and more preferably larger than
the width W4 between the side surfaces of the pressure chamber 164 in the lateral
direction. As a result, by making the width of the notch 1141 larger than that of
the heater 162 as a heat source and the pressure chamber 164, the thermal head cartridge
1 can further prevent heat from staying in the common ink flow path 115.
[0053] That is, by making the space width of the notch 1141 of the structural member 114
larger than the space width in the vicinity of the heat source of the nozzle plate
16, it is possible to prevent heat from being trapped in the slit 1123 communicating
with the nozzle plate 16.
[0054] If the liquid ejection device 2 and the thermal head cartridge 1 use a thermochromic
ink as a liquid, it is possible to prevent heat from causing discoloration, decolorization,
and color development of the thermochromic ink in the common ink flow path 115.
[0055] According to the thermal head cartridge 1 and the liquid ejection device 2 of the
embodiment described above, if the notch 1141 is disposed in the structural member
114 facing the slit 1123, it is possible to prevent the accumulation of heat in the
common ink flow path 115.
[0056] Although the example of the embodiment has been described above, the present disclosure
is not limited thereto. For example, in the above-described example, a configuration
having a plurality of thermal head cartridges 1 has been described as an example of
the liquid ejection device 2, but the present disclosure is not limited thereto. For
example, the thermal head cartridge 1 may be configured to be used in a mobile printer
or a handy printer . The thermal head cartridge 1 may be configured to be used alone
in a printer.
[0057] In the above-described example, as an example of the liquid used for the thermal
head cartridge 1, an example of a thermochromic ink containing a material (composition)
having a thermochromic property that discolors, decolorizes, and develops color by
heat has been described, but the present disclosure is not limited thereto. For example,
an ink that discolors, decolorizes, or develops color by light such as ultraviolet
rays may be used, or an ink that does not discolor may be used. The liquid is not
limited to ink, and may be, for example, a chemical solution or the like. Since the
thermal head cartridge 1 has a configuration capable of minimizing the accumulation
of heat in the common liquid flow path, it is preferable to use a liquid that is affected
by heat, such as change or deterioration due to heat. However, it goes without saying
that the thermal head cartridge 1 can be used for a liquid that is not affected by
heat.
[0058] In the above-described example, an example of integrally molding each configuration
with a resin material has been described, but the case 11 is not limited thereto .
For example, the case 11 may have a configuration in which the second case 112, the
filter holding frame 113, and the structural member 114 are integrally molded, and
the second case 112 and the first case 111 are molded separately. Such the first case
111 and the second case 112 may be integrally assembled by adhesion or welding after
molding.
[0059] According to at least one embodiment described above, it is possible to provide a
thermal head cartridge and a liquid ejection device capable of preventing the accumulation
of heat in a common liquid flow path.
[0060] While certain embodiments have been described, these embodiments have been presented
by way of example only, and are not intended to limit the scope of the inventions.
Indeed, the novel embodiments described herein may be embodied in a variety of other
forms; furthermore, various omissions, substitutions and changes in the form of the
embodiments described herein may be made without departing from the spirit of the
inventions. The accompanying claims and their equivalents are intended to cover such
forms or modifications as would fall within the scope and spirit of the inventions.