Ink supplying apparatus

Abstract

 An ink supplying apparatus is provided that houses two ink packages in an upper portion thereof, and supplies inks to print heads. Waste ink drawn by the purge operation is injected into a first waste liquid chamber via an injection opening, and then absorbed into an absorber. When the first waste liquid chamber becomes filled with waste ink, waste ink flows into the second waste liquid chamber via a vent hole, and then into the third waste liquid chamber. Therefore, even if the first waste liquid chamber becomes filled with waste ink, ink will not leak out. A small ink cartridge houses two ink packages. Since each ink cartridge has two separate ink packages storing individual inks, the amount of ink to be wasted at the time of ink cartridge replacement is reduced and, therefore, the operating cost is reduced.

Description

[0001] The invention relates to an ink supply apparatus for use in a printing apparatus that is designed to perform multi-color printing by using a plurality of color inks.

[0002] Typical printing apparatuses designed to perform multi-color printing by using a plurality of color inks use four color inks. Some high-quality printing apparatuses use six or eight color inks for printing. If separate containers are used to individually contain such color inks and the containers are formed as separate ink cartridges, the ease of handling deteriorates due to an increased cartridge replacement frequency. Moreover, an incorrect color ink cartridge may be mistakenly set in the printer during replacement. If such a mistake occurs, ink colors mix and other serious problems or damage may occur to the printer. Therefore, it is necessary to provide a mechanism for preventing the missetting of an ink cartridge.

[0003] If all the color inks used in a printing apparatus are contained in a single ink cartridge, the whole cartridge must be replaced even if only one of the color inks runs out. This is wasteful, and the cartridge replacement frequency becomes high. In particular, black ink is used at a high frequency and in a great amount since it is used for monochrome printing, such as text printing and the like. In many cases, black ink runs out earlier than the other color inks.

[0004] Therefore, many printing apparatuses employ two cartridges, that is, a cartridge containing only black ink, which is normally used frequently, and a cartridge containing the other three, five or seven color inks, for example, yellow, magenta, cyan and the like.

[0005] However, the three to seven or more color inks other than black ink, for example, yellow, cyan, magenta and the like, which are contained in a single cartridge are used at different frequencies and in different amounts. Normally, magenta ink is used in a relatively large amount. Therefore, there often occurs a case where a certain color ink that is frequently used runs out whereas the other color inks remain in large quantities and the whole ink cartridge must be replaced. Thus, large quantities of inks are wasted.

[0006] Accordingly, it is one aspect of the invention to provide an ink supplying apparatus for use in a printing apparatus capable of multi-color printing by using a plurality of color inks, wherein the amount of ink wasted is reduced, the ink cartridge replacement frequency is reduced, and thus, the operating cost is reduced.

[0007] To achieve the aforementioned and other objects of the invention, the invention provides an ink supplying apparatus or ink cartridge for use in a printing apparatus capable of performing multi-color printing by using a plurality of color inks, including a first ink cartridge having a storage device that stores two color inks, and a second ink cartridge having a storage device that stores two color inks other than the two color inks stored in the first ink cartridge.

[0008] The ink supplying apparatus of the invention reduces the cartridge replacement frequency and reduces the production cost of the cartridges in comparison with a construction in which color inks are contained in respective ink cartridges. Furthermore, in comparison with a construction in which an ink cartridge contains many color inks, the ink supplying apparatus of the invention reduces the amounts of inks to be wastefully discarded, reduces the incidence of replacement of ink cartridges, and thus reduces the operating cost.

[0009] In the ink supplying apparatus of the invention, an amount of ink storable in the first ink cartridge may be greater than an amount of ink storable in the second ink cartridge.

[0010] Thus, the ink supplying apparatus makes it possible to store color inks that are expected to be used in relatively great amounts, in the first ink cartridge, and store other color inks in the second ink cartridge.

[0011] In the ink supplying apparatus of the invention, each ink cartridge may be capable of storing the two color ink in substantially the same amount.

[0012] This ink supplying apparatus reduces the incidence of an event that only one of the inks in an ink cartridge runs out while the other ink remains in a great amount, even if the purge operation is frequently performed.

[0013] In the ink supplying apparatus of the invention, one of the two color inks stored in the first ink cartridge may be a black ink.

[0014] This ink supplying apparatus substantially equalizes the replacement frequencies of the first and second ink cartridges, since black ink, that is expected to be consumed in great amounts, is contained in one of the ink cartridges that has a greater ink storing capacity.

[0015] In the ink supplying apparatus of the invention, the first ink cartridge may be provided with a waste ink reservoir.

[0016] This ink supplying apparatus is advantageously able to store waste ink produced as a result of the purge operation of the printing apparatus, into a waste ink reservoir. Therefore, it becomes unnecessary to separately prepare a container, or the like, for storing waste ink. Since the ink cartridge is replaced when the ink therein runs out, the waste ink is removed together with the ink cartridge. Therefore, the ink supplying apparatus of the invention prevents an undesired event that waste ink overflows.

[0017] In the ink supplying apparatus of the invention, the waste ink reservoir may be disposed below the storage device of the first ink cartridge.

[0018] This ink supplying apparatus makes it possible to form a vent hole for releasing an amount of air corresponding to an amount of waste ink injected into the waste ink reservoir, in a portion of an upper portion of the waste ink reservoir, the portion being closer to a storage device. Therefore, if ink leaks when air is released, ink moves toward the storage device, so that ink is less likely to leak out of the ink cartridge.

[0019] In the ink supplying apparatus of the invention, the waste ink reservoir may have a plurality of liquid chambers that are separated by a partition having a communication hole.

[0020] The waste ink reservoir has a plurality of liquid chambers, so that if a large amount of waste ink is injected, ink will not enter the next liquid chamber until the first liquid chamber is filled with ink. Therefore, ink is further less likely to leak out.

[0021] In the ink supplying apparatus of the invention, the liquid chambers may have a waste ink absorbing member.

[0022] Since this ink supplying apparatus employs a waste ink absorbing member in the liquid chambers, waste ink injected into the liquid chamber can be absorbed and stabilized by the waste ink absorbing member. Therefore, ink movements are restricted so as to prevent ink from leaking out.

[0023] In the ink supplying apparatus of the invention, the waste ink absorbing member may be formed from a water-absorbing high-molecular material.

[0024] Since the waste ink absorbing member is formed from a water-absorbing high-molecular material, so that waste ink once absorbed into the absorbing member is fixed and, therefore, waste ink will not leak out.

[0025] In the ink supplying apparatus of the invention, at least one of the plurality of liquid chambers may be provided with a portion protruded downward.

[0026] Since the downward-protruded ink reservoir is provided, waste ink injected into this liquid chamber descends to a lower portion due to gravity, and therefore becomes stored in the protruded ink reservoir. Therefore, ink is prevented from moving into other liquid chambers, and leakage of waste ink to the outside is prevented.

[0027] In the ink supplying apparatus of the invention, an amount of waste ink storable in the waste ink reservoir may be at least an amount obtained by multiplying twice an amount of an ink stored in the first ink cartridge that is consumable by the printing apparatus, by a number of the ink cartridges.

[0028] In this ink supplying apparatus, the amount of waste ink never exceeds the aforementioned amount of ink even if the amount of ink consumed for the purge operation is far greater than the amount of ink used for the printing operation. Therefore, it never occurs that an amount of waste ink exceeding the capacity of the waste ink reservoir is injected thereinto. Therefore, an accident that waste ink overflows the waste ink reservoir and leaks out can be prevented.

[0029] In the ink supplying apparatus of the invention, the storage device of each ink cartridge may be a liquid container having a flexibility.

[0030] This ink supplying apparatus allows a weight reduction of the ink cartridge and therefore allows a weight reduction of the printing apparatus. The ink cartridge is able to supply ink in a favorable manner even if the ink cartridge is formed as a closed container having no vent hole to the outside. Therefore, leakage of ink to the outside can be prevented.

[0031] In the ink supplying apparatus of the invention, the storage device of each ink cartridge may be connected in communication to the print head via a flexible hollow tube.

[0032] The ink supplying apparatus of the invention makes it possible to provide an ink storage device separately from the print heads, in addition to the flexible liquid container. Therefore, the weight of the carriage can be reduced, and the load on the carriage motor (CR motor) is reduced. Hence, electric power consumption is reduced, the weight and size of the motor and other devices can be reduced, and the head control precision can be improved. Furthermore, if a large amount of ink is stored into the storage device, the weight of the movable portion is not affected, so that it becomes possible to store a large amount of ink.

[0033] In the ink supplying apparatus of the invention, the storage devices for the color inks in each ink cartridge may be disposed so as to have substantially equal height differences relative to the print heads for ejecting the corresponding inks.

[0034] This ink cartridge sets equal height differences between the ink storage device and the corresponding print heads, so that the hydraulic pressures on the heads due to the height differences become equal. Therefore, the meniscuses formed in nozzle openings of the heads become uniform, so that the ink cartridge achieves high-quality printing with good balance between the inks.

[0035] In the ink supplying apparatus of the invention, the printing apparatus may be an ink jet printing apparatus that has an ink jet head and performs printing by ejecting ink to a recording medium.

[0036] If the ink supplying apparatus of the invention is used together with an ink jet print head, particularly high-quality printing can be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] A preferred embodiment of the present invention will be described in detail with reference to the following figures wherein:

Fig. 1 is a front view of an exterior of a portable printer according to an embodiment of the invention;

Fig. 2 is a partially cutaway perspective view of the portable printer for schematic illustration of an internal structure of the printer;

Fig. 3A is a plan sectional view of the portable printer taken on line III-III of Fig. 1, illustrating a state assumed by a harness as print heads move, wherein a carriage is at the leftmost position;

Fig. 3B is a plan sectional view of the portable printer similar to the sectional view of Fig. 3A, wherein the carriage is at an intermediate position;

Fig. 3C is a plan sectional view of the portable printer similar to the sectional view of Fig. 3A, wherein the carriage is the rightmost position;

Fig. 4 is a schematic partially sectional view of the portable printer taken on line IV-IV of Fig. 1, viewed from the right-side end of the portable printer;

Fig. 5 is a schematic sectional view of the portable printer taken on line V-V of Fig. 1, viewed from the right-side end of the portable printer;

Fig. 6 illustrates a positional relationship between the carriage carrying thereon the print heads, a printing area, a print sheet, and a flushing area;

Fig. 7 is a plan partially sectional view of the portable printer taken on line VI-VI of Fig. 1;

Fig. 8 is a sectional view of a large ink cartridge taken on line VII-VII in Fig. 7, viewed from the back side thereof (upper side in Fig. 7);

Fig. 9 is a sectional view of a small ink cartridge taken on line VII-VII in Fig. 7, viewed from the back side thereof (upper side in Fig. 7);

Fig. 10 is a view of the large ink cartridge viewed from above (upper side in Fig. 1); and

Fig. 11 is a view of the small ink cartridge, viewed from above (upper side in Fig. 1).

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0038] A first preferred embodiment of the invention will be described with reference to the accompanying drawings. As best shown in Figs. 1 and 2, a portable printer 1 has therein a large ink cartridge 8 and a small ink cartridge 9 (hereinafter, collectively referred to as "ink cartridges 8/9") that are disposed at predetermined positions. The portable printer 1 performs printing by supplying inks from the ink cartridges 8/9 to a right-side print head 15 and a left-side print head 16 (hereinafter, referred to as "print heads 15/16"), and ejects inks from right-side nozzles 15a and left-side nozzles 16a (hereinafter, referred to as nozzles 15a/16a) arranged in the print heads 15/16 to a print sheet PP while moving a carriage 27 that supports the print heads 15/16 back and forth in main scanning directions perpendicular to the direction of sheet conveyance.

[0039] Fig. 1 is an external front elevation of the portable printer 1 according to the embodiment of the invention. The portable printer 1 has a printer body 3 that is a case having a generally rectangular box shape. Formed in a substantially central portion in a lower portion of the printer body 3 is a sheet discharge opening 4 having a generally rectangular shape that is elongated in the directions of the length of the portable printer 1 (right-to-left directions in Fig. 1). The sheet discharge opening 4 is an opening for discharging the print sheet PP after printing. The elongated width of the sheet discharge opening 4, that is, the dimension thereof in the directions of the length of the portable printer 1, is defined corresponding to the width of the print sheet PP. In the portable printer 1 of the embodiment, the elongated width of the sheet discharge opening 4 is greater than the width of the A4-size sheets (about 210 mm). An upper portion of the printer body 3 has a lid 7 for replacement of the ink cartridges 8/9.

[0040] Fig. 2 is a partially cutaway schematic perspective view of an internal structure of the portable printer 1. In Fig. 2, an arrow X indicates the direction of conveyance of the print sheet PP, and an arrow Y indicates a moving direction of the print heads 15/16 during main scanning.

[0041] As shown in Fig. 2, the printer body 3 also serves as a body frame 6 having a generally rectangular box shape. Generally rectangular shelf-shaped cartridge frames 5 are disposed in an upper space 1a of the body frame 6. A partition 5a extends below the cartridge frames 5 throughout substantially the entire length of the body frame 6 along a rearward side thereof, separating the upper space la from a lower space 1b. The partition plate 5a defines an opening in front thereof, whereby the upper space la communicates with the lower space 1b. The ink cartridges 8/9 are arranged horizontally on the cartridge frames 5, with their upper ends being flush with one another.

[0042] Disposed in the lower space 1b of the body frame 6 of the portable printer 1 is the carriage 27 movable back and forth within the printer body 3 in the direction of the arrow Y and the opposite direction, that is, in the main scanning directions. The carriage 27 carries thereon the print heads 15/16 aligned in the main scanning directions. The print heads 15/16 eject inks for printing. The right-side print head 15 is provided with the right-side nozzles 15a arranged along the lower surface of the head. More specifically, the nozzles 15a define two rows of many nozzle openings 18 that are arranged in the sheet conveying direction X, and each nozzle opening 18 is equipped with a piezoelectric element.

[0043] The nozzle openings 18 in one of the two rows are filled with a magenta ink supplied from a corresponding one of ink packages 8a. The nozzle openings 18 in the other row are filled with a black ink supplied from a corresponding one of the ink packages 8a. Similarly, the left-side print head 16 is provided with the left-side nozzles 1 6a arranged along a lower surface of the head, and each nozzle opening thereof is filled with a yellow or cyan ink. Hereinafter, yellow, magenta, cyan and black are referred to as "Y", "M", "C" and "K". Therefore, the Y, M, C and K inks are ejected from the rows of nozzle openings 18 to perform color printing.

[0044] When voltage is applied to the nozzles 15a/16a equipped with piezoelectric elements, the nozzles 15a/16a contract due to deformation proportional to the value of voltage. Upon contraction, the nozzles 15a/16a eject the inks from the nozzle openings 18 to the print sheet PP, thus performing printing.

[0045] The two generally rectangular box-shaped ink cartridges 8/9 are detachably disposed in a horizontal posture on the cartridge frames 5 within the upper space la of the portable printer 1, that is, above the print heads 15/16. The partition 5a extends below the ink cartridges 8/9. Of the ink cartridges 8/9, the large ink cartridge 8 disposed on the left side in Fig. 2 houses the ink package 8a containing the magenta and black inks. That is, the ink packages 8a are formed by two ink packages. One of the ink packages 8a contains the magenta ink, and the other contains the black ink.

[0046] A lower portion of the large ink cartridge 8 has a waste ink reservoir 8b for holding waste ink sucked by a purge operation (described below) for preventing ink clogging of the print heads 15/16.

[0047] Immediately to the right of the large ink cartridge 8 in Fig. 2, the small ink cartridge 9 is detachably disposed in a horizontal posture with the upper end thereof being flush with that of the large ink cartridge 8. Similar to the large ink cartridge 8, the small ink cartridge 9 houses two ink packages 9a. Each ink package 9a contains one of the yellow and cyan inks, which are ejected from the left-side print head 16. The small ink cartridge 9 and the ink packages 9a are smaller than the large ink cartridge 8 and the ink packages 8a, respectively. That is, the amount of ink contained is less in each of the ink packages 9a than in each of the ink packages 8a. More specifically, each ink package 8a is capable of containing 8 mL of ink whereas each ink package 9a is capable of containing only 5.5 mL of ink. The capacities of the ink packages are thus set because of the different ink ejection amounts of the nozzles 15a/16a of the print heads 15/16.

[0048] The ink packages 8a/9a housed in the ink cartridges 8/9 are formed by generally rectangular-shaped ink packages. Each ink package is formed by a laminate film material obtained by laminating a plurality of film sheets, for example, about ten film sheets, which are formed from a polyethylene resin or the like. The laminate film material of the ink packages 8a/9a has such great rigidity and strength as to provide the ink packages 8a/9a with a shape restoring characteristic, whereby shape changes of the ink packages 8a/9a can be curbed. Therefore, when inks are supplied from the ink packages 8a/9a to the print heads 15/16 and the amounts of inks contained in the ink packages 8a/9a decrease, the ink packages 8a/9a will not be flattened or deformed inward by the atmospheric pressure, but will maintain a suitable negative internal pressure therein.

[0049] The large ink cartridge 8 will be described in detail. As shown in Fig. 2, the external configuration of the large ink cartridge 8 is a generally laterally elongated rectangular platy configuration in which a rectangular protrusion 84 is provided in a lower leftward portion in Fig. 2 (see Fig. 4). Fig. 8 is a sectional view of the large ink cartridge 8 taken on line VII-VII in Fig. 7, viewed from the back side (upper side in Fig. 7). Although not conforming to an actual configuration, extraction openings 88 and an injection opening 85 are shown in Fig. 7.

[0050] Fig. 10 is a view of the large ink cartridge 8 viewed from above (from the upper side in Fig. 1).

[0051] As shown in Fig. 8, the large ink cartridge 8 is divided into an upper portion and a lower portion by a partition 89. An ink package housing portion 82 is formed in the upper portion. The ink package housing portion 82 houses two ink packages 8a. The extraction openings 88 are formed in the back side (the upper side in Fig. 7) of the large ink cartridge 8, as shown in Fig. 8. The extraction opening 88 is fixed to the back side of the large ink cartridge 8 in such a manner that a portion of each extraction opening 88 is exposed on the external wall of the large ink cartridge 8. The exposed portion of each extraction opening 88 is formed by a rubber-made film. An ink extracting needle 10 is put into the rubber film of each extraction opening 88 as shown in Fig. 10. Each ink extracting needle 10 has an extraction hole 10a in its distal end placed in the corresponding ink package 8a. Therefore, in each ink package 8a, ink flows into the ink extracting needle 10 via the extraction hole 10a, and flows into an ink supply tube 12 connected to the base end of the ink extracting needle 10 by a coupling member 11 (not shown in Figs. 8 and 10). Ink is thus supplied to a corresponding print head 16.

[0052] The waste ink reservoir 8b is formed in the lower portion separated by the partition 89. A space defined between a right-side end portion of the ink package housing portion 82 and a right-side end wall of the large ink cartridge 8 also forms a portion of a first waste liquid chamber 83a. The injection opening 85 to this space is formed. The injection opening 85 is formed by a rubber film. An injection needle 70 is put into the rubber film of the injection opening 85. Waste ink drawn by the purge operation is conducted to the charging needle 70 by a waste ink tube 66, and injected from an injection hole 70a formed in the distal end of the charging needle 70 into the first waste liquid chamber 83a. An absorber 87 is provided in the space.

[0053] The absorber 87 is formed from a material formed by a mass of many fibers forming many gaps therebetween in this embodiment. The absorber 87 may also be formed by a porous material such a sponge-like material and the like. That is, the absorber 87 needs only to absorb and fix waste ink liquid. Therefore, the absorber 87 may be, for example, a polymer obtained by grafting acrylate salt to starch, a polymer obtained by grafting acrylate salt to a carboxyl methylcellulose, other water-absorbing high molecular polymers, for example, synthetic polymers such as polyacrylate polymers, vinyl hydrochloride-acrylate copolymers, isobutylene-maleate copolymers, polyvinyl alcohols, and the like. Since waste ink absorbed in the absorber 87 is fixed between high-molecular chains, there is no danger of leakage of waste ink.

[0054] The first waste liquid chamber 83a is contiguous to the aforementioned space, and to a lower portion of the right-side ink package 8a in Fig. 8, and to the protrusion 84 protruded from a lower portion. This space portion also houses an absorber similar to the absorber 87 for absorbing waste ink injected into the first waste liquid chamber 83a from the injection hole 70a. The protrusion 84 has a downward-protruding shape, so that absorbed waste ink is collected and stored at the protrusion 84 by gravity.

[0055] An upward-protruded space is defined to the left of the first waste liquid chamber 83a. The partition 89 partially defining the space has a vent hole 86.

[0056] A space defined to the left of the first waste liquid chamber 83a and below the left-side ink package 8a, in Fig. 8, is divided by the partition 89 into three spaces, that is, a second waste liquid chamber 83b, a third waste liquid chamber 83c and a fourth waste liquid chamber 83d. Each of the waste liquid chambers 83a/83b/83c separated by the partition 89 houses an absorber 87 as described above.

[0057] Each of the partitions 89, separating the first waste liquid chamber 83a, the second waste liquid chamber 83b, the third waste liquid chamber 83c, and the fourth waste liquid chamber 83d, has a vent hole 86 through which air or waste ink can pass. An upward-protruding space is defined to the left of the fourth waste liquid chamber 83d in Fig. 8. A side wall of the space has a vent hole 86.

[0058] The ink cartridges 8/9 are disposed above the print heads 15/16 for supplying inks to the print heads 15/16. Since the large ink cartridge 8 and the small ink cartridge 9 are horizontally disposed at the same height, the ink packages 8a/9a in the ink cartridges 8/9 are disposed on a single horizontal plane. The nozzles 15a/16a formed in the nozzle surface portions of the print heads 15/16 are also located on a single horizontal plane. Therefore, the ink packages 8a/9a of the four color inks and the corresponding nozzles have equal height differences. Due to the equal height differences, the hydraulic pressures on the nozzles become also equal and constant, so that the color ink nozzles have a uniform internal pressure and therefore the inks can be supplied uniformly.

[0059] The ink pressure supplied to the print heads 15/16 is kept at a uniform negative pressure, so that the each nozzle opening 18 of the nozzles 15a/16a of the print heads 15/16 has a concave meniscus (curved surface) of ink liquid. Since the internal pressure in the print heads 15/16 is maintained uniformly, the ink ejection characteristic of the nozzles 15a/16a of the print heads 15/16 can be maintained, so that good print quality can be maintained. In the case of the print heads 15/16 of this embodiment, as for example, a concave meniscus of ink can be formed in each nozzle opening 18 (see Fig. 6) of the nozzles 15a/16a if the supplied ink pressure is within the range (operating pressure range) of about 0 mmAq (water column) to about -300 mmAq (water column) relative to the atmospheric pressure. An optimal operating pressure range of the print heads 15/16 for the print operation by the portable printer 1 of this embodiment is from about -30 mmAq (water column) to about -100 mmAq (water column) relative to the atmospheric pressure.

[0060] A control unit 34 having a CPU, an input buffer memory, a head driving IC and the like is disposed to the left of the ink cartridges 8/9 in the upper space la of the portable printer 1 in Fig. 2. Four flexible printed cables (FPCs) 35 for applying voltages to the print heads are connected to the control unit 34. The four head driving FPCs 35 are stacked near a rearward end portion of the control unit 34 (an end portion toward the rear side in Fig. 2) in the upper space la of the portable printer 1. The head driving FPCs 35 are then laminated on the forward side (in Fig. 2) of ink supply tubes 12 (described below) near a rear end portion of the large ink cartridge 8 in the upper space 1a of the portable printer 1. The ink supply tubes 12 are stacked vertically and connected to the ink cartridges 8/9. The head driving FPCs 35 are film-shaped cables formed by forming a wiring pattern of an electrically conductive layer on a polyimide substrate and covering the wiring pattern with a protective layer.

[0061] Fig. 4 is a schematic partially sectional view of the portable printer 1 taken on line IV-IV of Fig. 1, wherein a carriage (CR) motor 30 is omitted to simplify the illustration. As can be seen in an upper portion of the drawing of Fig. 4, the ink extracting needles 10 for the individual color inks are put into the ink packages 8a/9a housed in the ink cartridges 8/9. The ink extracting needles 10, provided for extracting inks from the ink packages 8a/9a, are formed from a corrosion-resistant metallic material, such as stainless steel or a ceramic material, or the like. Each ink extracting needle 10 is a hollow needle having in its distal end portion (left-side end portion in Fig. 4) an extracting hole 10a for extracting an ink from the ink package 8a or 9a. The ink extracting hole 10a of each ink extracting needle 10 is in communication with an internal space of the needle. Therefore, when the ink extracting needles 10 are put into the ink packages 8a/9a, the inks can flow from the ink packages 8a/9a into the internal spaces of the needles via the ink extracting holes 10a.

[0062] In the large ink cartridge 8, a charging needle 70 for charging waste ink sucked by the purge operation (described below) and conducted to the charging needle 70 via a waste ink tube 66 (see Fig. 7), is put into a first waste ink chamber 83. Waste ink is thereby charged into the large ink cartridge 8.

[0063] As shown in Fig. 4, a base end portion of each ink extracting needle 10 (an end portion opposite to the tip end thereof, that is, an end portion on the right side in Fig. 4) put into the corresponding one of the ink packages 8a/9a of the four color inks is coupled to an end of the generally "L"-shaped coupling member 11, near the rear end of the upper space la of the portable printer 1 (the right side end thereof in Fig. 4). The other end of each coupling member 11 is connected to the corresponding one of the ink supply tubes 12. Each coupling member 11 has a hollow tubular shape, in which a communication hole (not shown) is formed for communication with the ink extracting hole 10a of the corresponding one of the ink extracting needles 10. The ink supply tubes 12 are generally hollow cylindrical flexible tubes formed from a synthetic resin such as polypropylene, polyethylene, polyurethane, polyvinyl chloride, or the like. The ink supply tubes 12 allow ink to flow therethrough in order to supply ink to the print heads 15/16.

[0064] In the embodiment, each ink supply tube 12 is formed by a TYGON® tube made by NORTON. The wall thickness thereof is within the range of about 0.5 mm to about 1.5 mm, and the tube inside diameter is within the range of about 0.5 mm to about 1.5 mm. Each ink supply tube 12 in this embodiment, as for example, is formed by a TYGON tube having a wall thickness of about 0.8 mm, an inside diameter of about 0.8 mm, and an outside diameter (equal to the sum of twice the wall thickness and the inside diameter) of about 2.4 mm. The minimum value of the radius R of curvature (minimum radius of curvature) of the ink supply tubes 12 in a bent state is about 20 mm.

[0065] The four ink supply tubes 12 will be further described with reference to Figs. 2 and 4. Near a substantially central portion of the rear end portion (far end side in Fig. 2) of the upper space 1a of the portable printer 1, the ink supply tubes 12 connected to the ink packages 8a/9a are stacked and bundled into a vertical row by elongated rectangular annular shaped binders (not shown). The four head driving FPCs 35 stacked and connected to the control unit 34 are placed and attached onto the inward side of the curved ink supply tubes 12, that is, the forward side of a far-side portion thereof. The outward side of the curved ink supply tubes 12, that is, the rearward side of a far-side portion thereof, is covered with a protective film 14 for protecting the ink supply tubes 12 from interference with the body frame 6.

[0066] The protective film 14 is a protective member for ensuring smooth sliding of the ink supply tubes 12 on an inner wall of the body frame 6 if the ink supply tubes 12 contact the inner wall of the body frame 6. The protective film 14 is normally a film formed from a material that achieves a low surface adhesion or tackiness. The protective film 14 needs to be able to support itself or retain its shape and also needs to be able to bent together with the ink supply tubes 12 and the head driving FPCs 35 so as to follow the movements of the print heads 15/16. The thickness of the protective film 14 is preferably within the range of about 25 µm to about 300 µm. In this embodiment, the protective film 14 is formed by a polyethylene terephthalate (PET) film having a thickness of about 100 µm.

[0067] Therefore, the head driving FPCs 35, the ink supply tubes 12 and the protective film 14 are laminated in that order from the near side in Fig. 2, at a location near a substantially central portion of the rear end portion (far side in Fig. 2) of the upper space la. These members are bundled together at predetermined intervals by generally angled "8"-shaped binders 13 each of which has a wide opening and a narrow opening. The narrow opening of each binder 13 closely contacts and firmly holds the four stacked ink supply tubes 12 so as to retain the stack. The wide opening of each binder 13 is about four to five times as wide as the narrow opening. The wide opening of each binder 13 bundles the four head driving FPCs 35 so that the bundle of the head driving FPCs 35 is not greatly apart from the bundle of the four ink supply tubes 12. The wide opening of each binder 13 allows the head driving FPCs 35 to substantially freely slide therein. Therefore, the binders 13 secures an appropriate space that allows the head FPCs 35 to escape inward when the two bundles are bent, so that the bending thereof will not be impeded but can easily be performed. The protective film 14 is disposed on the outside of each binder 13 so as to cover the ink supply tubes 12.

[0068] The four ink supply tubes 12 and the four head driving FPCs 35 are bundled by the binders 13 at intervals of about 5 cm. The two bundles are bent from a rightward orientation toward the near-side end of the portable printer 1 in Fig. 2 on a plane of the partition 5a while the stacks of the bundles are maintained. At a location near the forward end portion of the upper space la (the near side thereof in Fig. 2) of the portable printer 1, the bundles are bent toward the print heads, that is, leftward in Fig. 2 since the print heads 15/16 are at an initial position that is shown leftward. The bundles are then connected to a connecting portion provided in an upper portion of the print heads 15/16. The four color inks are conducted to the designated print heads 15/16 via the corresponding ink supply tubes 12.

[0069] The ink supply tubes 12 are vertically stacked and bundled by the binders 13. This arrangement prevents the ink supply tubes 12 from hanging or bending down (downward in Fig. 2) due to gravity. Furthermore, the partition 5a disposed below the ink supply tubes 12 supports the four ink supply tubes 12 from below, thereby preventing the ink supply tubes 12 from hanging or bending down due to gravity. Further, the ink supply tubes 12 are substantially sandwiched by the elastic protective film 14 and the elastic head driving FPCs 35, so that the stack of the ink supply tubes 12 are prevented from bending at sharp angles, except for the aforementioned curved portion of the stack. This arrangement prevents an undesired event that the stack of the ink supply tubes 12 folds or bends at a sharp angle so that the inward sectional area of the ink passages decreases and an energy loss of the inks flowing through the ink supply tubes 12 occurs. Still further, the sandwich arrangement with the elastic members also prevents an undesired band of the bundle of the ink supply tubes 12 on a protrusion 84 (shown in Fig. 4) of the waste ink reservoir 8b of the large ink cartridge 8, which is located inside the curve of the bundles of the ink supply tubes 12 and the head driving FPCs 35.

[0070] The collective bundle of the protective film 14, the stack of the ink supply tubes 12 and the stack of the head driving FPCs 35 will hereinafter be referred to simply as "harness 17". Figs. 3A, 3B and 3C are plan sectional views of the portable printer 1 taken on line III-III of Fig. 1, illustrating different states of the harness 17 assumed as the print heads 15/16 move. In Figs. 3A to 3C, unrelated portions are omitted from the illustration. As shown in Figs. 3A to 3C, the harness 17 extends from a substantially central portion of the rearward end portion of the upper space 1a (the far side in Fig. 2), and connects to the upper portion of the print heads 15/16. In Figs. 3A to 3C, the direction indicated by an arrow Y is a main scanning direction.

[0071] Fig. 3A illustrates a state that the print heads 15/16 are at the initial position before printing, that is, the right-side print head 15 is at the left-side end of a platen 32 that defines a printing area 43. In the state shown in Fig. 3A, the print heads 15/16 are at a leftmost position in the drawing. In this state, the left-side print head 16 is positioned over a left-side flushing area 42. In this state, the protective film 14 of the harness 17 is pressed against the forward wall of the body frame 6 (lower side thereof in Fig. 3A) since the harness 17 tends to straighten due to its elasticity. When the CR motor 30 is operated upon application of a voltage, and therefore moves the carriage 27 together with the print heads 15/16, as shown in Fig. 2, from the aforementioned state to the right, that is, in the printing direction Y, the harness 17 connected to the print heads 15/16 is also moved following the movement of the print heads 15/16. In this case, the harness 17 moves while pressing the protective film 14 against the forward wall (lower side in Fig. 3) of the body frame 6 so that the protective film 14 slides on the forward wall of the body frame 6.

[0072] Fig. 3B illustrates a state that the carriage 27 has been moved in the direction Y. In this state, the harness 17 has progressively moved to the rearward wall (upper side in Fig. 3B) of the body frame 6, and therefore the length of the curved portion of the harness 17 has decreased so that the harness 17 is now out of the sliding contact with the forward wall (lower side in Fig. 3B) of the body frame 6. Therefore, the movement resistance of the carriage 27 has decreased, and the load on the CR motor 30 has decreased.

[0073] Fig. 3C illustrates a state that the carriage 27 has been further moved in the direction Y to the rightmost position. In addition, the right-side print head 15 is positioned over a right-side flushing area 41. In this state, the harness 17 is apart from the forward wall (lower side in Fig. 3C) of the body frame 6, so that no sliding resistance occurs with respect to the forward wall of the body frame 6.

[0074] Although the foregoing embodiment pursues a compact design of the print heads by providing rows of nozzle openings for two color inks in each print head, it is also possible to provide rows of nozzle openings for the color inks in respective print heads. Which one of the print head constructions to select is based on the balance between the production cost and the compact design requirements. Therefore, the number of print heads employed is not limited to two, but may also be more than two. A construction employing more than two print heads will be described below.

[0075] In Fig. 4, an arrow X indicates the print sheet PP conveying direction. As shown in Fig. 4, an insert opening 22 for inserting unused print sheets PP is formed in a rearward lower portion (the right side in Fig. 4) of the printer body 3. Disposed downstream of the insert opening 22 in the direction of conveyance of each print sheet PP inserted into the insert opening 22 are a conveying roller 23 for conveying each print sheet PP and a pressure roller 24 for pressing the print sheet PP against the conveying roller 23. The conveying roller 23 is driven by a line feed motor (LF motor) formed by a pulse motor. The conveying roller 23 and the pressure roller 24 cooperate to convey each print sheet PP while pressing and clamping the sheet.

[0076] Disposed downstream of the conveying roller 23 and the pressure roller 24 are a discharge roller 25 driven by the LF motor 31 for discharging the print sheet PP conveyed from the conveying roller 23 out of the printer body 3, and a pressure roller 26 for pressing the print sheet PP against the discharge roller 25. The discharge roller 25 and the pressure roller 26 cooperate to discharge each print sheet PP via the sheet discharge opening 4.

[0077] The print heads 15/16 are disposed over the print sheet PP positioned between the conveying roller 23 and the discharge roller 25. The print heads 15/16 are detachably mounted to the carriage 27 and movable back and forth in directions substantially perpendicular to the sheet of the drawing of Fig. 4, that is, the direction indicated by the arrow Y in Fig. 2 and the opposite direction, along a guide bar 29 supported by the body frame 6 of the printer body 3. The surfaces of the print heads 15/16 facing the print sheet PP have the nozzles 15a/16a for ejecting the inks to the print sheet PP held by the conveying roller 23 and the like.

[0078] The carriage 27 carrying thereon the print heads 15/16 will be described with reference to Figs. 2 to 4. The carriage 27 disposed in the lower space 1b of the printer body 3 is supported by the guide bar 29, which extends through a rear portion of the carriage 27 (a right-side portion thereof in Fig. 4) in the main scanning directions. The carriage 27 is movable in the main scanning directions, guided by the guide bar 29. A drive pulley 38 is connected to a rotating shaft of the CR motor 30 disposed at a right-side end in the portable printer 1 in Fig. 2. The drive pulley 38 and a driven pulley 39 disposed at a left-side end in Fig. 2 are connected by a timing belt 36. The carriage 27 is fixed to a portion of the timing belt 36. When a voltage is applied to the CR motor 30 by the control unit 34, the CR motor 30 operates to rotate the drive pulley 38 and therefore the timing belt 36. In this manner, the carriage 27 is moved along the guide bar 29 in the main scanning directions (the direction of the arrow Y in Fig. 2 and the opposite direction).

[0079] A timing fence 33 for recognizing the position of the carriage 27 is provided on the rear side of the carriage 27 (the right side thereof in Fig. 4). The timing fence 33 is a linear type encoder formed by a finely slitted glass plate. Two photosensors (not shown) are provided which are slightly shifted in phase relative to the slit cycle. Each photosensor is formed by a combination of a light emitter formed by a light-emitting diode (LED) and a light receiver formed by a photo-transistor. In each photosensor, the light emitter and the light receiver are disposed at the opposite sides of the timing fence 33. An origin detecting photosensor is also provided. The position of the carriage 27 is detected by the light receiver (not shown) of each photosensor detecting light travelling from the light emitter (not shown) via the timing fence 33. The phase difference between the aforementioned two photosensors is set to 1/2 of the phase of the slits so as to detect the moving direction of the carriage 27. The aforementioned origin detecting photosensor is used to detect the original position of the carriage 27. The data based on pulses obtained from the photosensors are accumulated and analyzed by the CPU of the control unit 34 so as to perform increment-type control for detection of the position of the carriage 27. The transmission-type timing fence 33 may be replaced by a reflection-type timing fence. In such a case, the timing fence 33 is formed by a plate of aluminum or the like on which fine stripes are printed or baked, and the position of the carriage 27 is detected by a laser light emitter emitting light to the timing fence 33 and a light receiver detecting light reflected from the timing fence 33. It is also possible to employ a timing fence having absolute-type graduations.

[0080] The CR motor 30 is a direct-current (DC) motor, and can be controlled in speed through PWM control or DC value control. Based on the positional information from the timing fence 33, the present position of the carriage 27 is recognized, and the speed and the acceleration of the carriage 27 are determined. Based on the thus-obtained date, feedback control through PDI control is performed.

[0081] Fig. 5 is a sectional view of the portable printer 1 taken on line V-V in Fig. 4. In Fig. 5, an arrow Y indicates a direction of movement of the carriage 27. A central portion of the discharge roller 25 is omitted from the illustration.

[0082] As shown in Fig. 5, the CR motor 30 for supplying drive forces to reciprocate the carriage 27 in the right-to-left directions in Fig. 5 (the direction of the arrow Y and the opposite direction) is disposed on an upper portion of the body frame 6, in a right-side portion of the printer body 3. Disposed below the CR motor 30 is the LF motor 31 for rotating the conveying roller 23 and the discharge roller 25.

[0083] The flushing operation will be described with reference to Figs. 3 and 8. The print heads 15/16 (ink jet heads) for ejecting inks from the nozzle openings 18 employ inks each of which contains a fast drying solvent in order to ensure fast drying and fixation of the inks on a print sheet PP after the inks are ejected thereto. When the portable printer 1 is not used, the nozzles 15a/16a are covered with a first cap 62 and a second cap 63 (hereinafter, referred to as "caps 62/63") to prevent the inks in the nozzle openings 18 from drying. In the case of monochrome printing, ink is constantly ejected, so that ink in the nozzle openings is constantly refreshed. Therefore, an ink viscosity increase due to the drying of ink normally does not occur in monochrome printing.

[0084] In the case of color printing, however, some of the color inks can be left unused for a long time. An ink that is not ejected from but remains in the nozzle openings 18 exposed to external air for a relatively long time is likely to dry and have an increased viscosity. Therefore, nozzle openings 18 for a certain color ink may become clogged during a long-time printing operation. Therefore, a flushing area is provided for withdrawing the print heads 15/16 from the platen 32 corresponding to the printing area 43, that is, from the area of a print sheet PP. When the printing operation has continued for a predetermined length of time, the print heads 15/16 are withdrawn into the flushing area, and then the inks are ejected to a pre-disposed ink absorber in order to renew ink whose viscosity has increased due to long-time dwelling in nozzle openings 18. The clogging of the nozzle openings 18 is thereby prevented. The portable printer 1 of the embodiment performs the flushing operation at the start and end of each printing operation and at every elapse of ten seconds during the printing operation.

[0085] A flushing mechanism according to the embodiment will be described. Fig. 6 illustrate a positional relationship between the carriage 27 carrying thereon the print heads 15/16, the printing area 43, the print sheet PP, and flushing areas 41/42. Fig. 3A illustrates the state that the carriage 27 is at the leftmost position in the drawing. In this state, the left-side print head 16 is positioned directly over the left-side flushing area 42, and the right-side print head 15 is positioned over the left-side end of the platen 32 (see Fig. 6). The width of the platen 32 measured in the direction Y is substantially equal to the maximum print sheet PP width that allows the printing by the portable printer 1, so that if a print sheet PP of the maximum width is used, printing can be performed by the right-side print head 15 at the position over the left-side end of the platen 32. If ink is ejected from the left-side nozzles 16a of the left-side print head 16 in the state shown in Fig. 3A, ink deposits on a left-side absorber 42a that is disposed in the left-side flushing area 42. The left-side absorber 42a is formed by a mass of fibers that embraces many gap spaces, so that ink is quickly absorbed upon deposition on the left-side absorber 42a.

[0086] When the left-side print head 16 is positioned in the left-side flushing area 42 as shown in Fig. 3A, the right-side print head 15 can start printing in the printing area 43 while the left-side print head 16 is performing the flushing operation. Therefore, the flushing operation can be performed without stopping the printing operation. That is, the flushing operation can be performed without degrading the throughput of the printing apparatus.

[0087] Fig. 3C shows the state that the carriage 27 is at the rightmost position in the drawing. In this state, the right-side print head 15 is positioned directly over the right-side flushing area 41, and the left-side print head 16 is positioned over the right-side end of the platen 32 (see Fig. 6). In this state, therefore, the right-side print head 15 can perform the flushing operation in the right-side flushing area 41, and the left-side print head 16 can perform printing if the print sheet PP extends under the left-side print head 16. That is, it is possible to perform the flushing operation of the right-side print head 15 while performing the printing operation.

[0088] The purge operation and a mechanism therefor will be described. Similar to the flushing operation, the purge operation is mainly intended to prevent the clogging of the nozzles 15a/16a of the print heads 15/16. Whereas the flushing operation is periodically performed during printing to eject ink from the nozzles 15a/16a in the flushing areas 41/42 for the purpose of preventing the nozzles 15a/16a from drying, the purge operation is performed to forcibly discharge ink from the print heads 15/16 if the ink viscosity is so high that the flushing operation cannot discharge ink. When the printer is not used, the print heads 15/16 are covered with the caps 62/63 in order to substantially prevent the print heads 15/16 from drying. However, the actual sealing of the caps 62/63 is not perfect, so that ink in the print heads 15/16 gradually dries although the heads are covered with the caps 62/63. Therefore, if the printer is left unused for a long time, ink in the nozzles 15a/16a may become dry and viscous so that the ink cannot be discharged by the flushing operation. In such a case, a suction pump is operated to forcibly discharge the highly viscous ink from the nozzles 15a/16a.

[0089] The purge mechanism of the embodiment will be described with reference to Fig. 7. Fig. 7 is a plan partially sectional view of the portable printer 1 of the embodiment taken on line VI-VI in Fig. 1, wherein a pump 65 is shown in a sectional view and an irrelevant portion is omitted from the illustration.

[0090] The LF motor 31 for conveying the print sheet PP operates upon application of a voltage thereto. For purging, drive power is transmitted from the LF motor gear 37 to a pump driving gear 61 via an LF motor gear 37. Drive power is then transmitted from the pump driving gear 61 to a pump driving cam 64 via a bevel gear provided on a distal end of the pump driving gear 61, so that the pump driving cam 64 is rotated. The pump driving cam 64 is a hollow cylindrical member that is open downward. The pump driving cam 64 has on its upper surface a bevel gear that meshes with the bevel gear of the pump driving gear 61. The pump driving cam 64 has an inner guide groove 64a and an outer guide groove 64b each of which has a modified annular configuration. Another groove (side groove) 64c extends around a peripheral surface of the pump driving cam 64. A protrusion (not shown) corresponding to a photosensor 68 is provided on an inner lower surface of the opening of the pump driving cam 64. The protrusion is detected by the photosensor 68, so that the initial position of the pump driving cam 64 is detected.

[0091] The pump 65 is disposed to the left of the pump driving cam 64 in the drawing. The pump 65 has two pistons, that is, a first piston 65d and a second piston 65e. The first piston 65d has a tubular rod whose distal end is provided with an outer follower 65b that is a driven portion guided by the outer groove 64b. The second piston 65e has a rod that extends through the tubular rod of the first piston 65d. The distal end of the rod of the second piston 65e is provided with an inner follower 65a that is a driven portion guided by the inner groove 64a. The pump 65 has an inlet 65c and an outlet 65f that is formed in an upper right portion of the pump 65. The inlet 65c is connected to a hollow purge tube 67. The purge tube 67 is connected in communication to the caps 62/63. Therefore, the purge operation is performed simultaneously for the first cap 62 and the second cap 63.

[0092] The outlet 65f of the pump 65 is connected to a hollow waste ink tube 66 that is connected in communication to the waste ink reservoir 8b of the large ink cartridge 8. Therefore, all the color inks are held as waste ink in the waste ink reservoir 8b of the large ink cartridge 8.

[0093] The first cap 62 and the second cap 63 are disposed to the right of the pump driving cam 64. The caps 62/63 are moved by a driven element (not shown) guided by the side groove 64c formed in the peripheral surface of the pump driving cam 64 when the pump driving cam 64 is rotated. The caps 62/63 are raised and lowered by a cap raising/lowering portion 69.

[0094] The purge operation will be described in detail with reference to Fig. 7. When purging is necessary, voltage is applied to the CR motor 30 (see Fig. 2) by a predetermined control device in order to move the carriage 27. When the print heads 15/16 are moved to a position over the caps 62/63, the position of the print heads 15/16 is detected by the timing fence 33, and the purge operation is started. Rotation is transmitted from the LF motor 31 to the pump driving cam 64 by the LF motor gear 37, and the pump driving cam 64 rotates from the initial position. Therefore, the driven element is moved by the side groove 64c of the pump driving cam 64 so as to move the cap raising/lowering portion 69. The caps 62/63 are thereby raised to tightly cover the surfaces of the nozzles 15a/16a of the print heads 15/16.

[0095] When being at the initial positions, the first piston 65d and the second piston 65e are substantially in contact with each other. The first piston 65d closes the outlet 65f when at the initial position. The second piston 65e closes the inlet 65c when at the initial position. Subsequently, the first piston 65d, the second piston 65e and the cap raising/lowering portion 69 operate as described below, guided by the pump driving cam 64.

[0096] After the caps 62/63 are raised, the second piston 65e is moved leftward and the distance between the first piston 65d and the second piston 65e increases. Therefore, the capacity defined between the two pistons increases while negative pressure grows therein. Simultaneously, the inlet 65c becomes open from the closed state previously achieved by the first piston 65d. Due to the negative pressure caused by the pump 65, a negative pressure also occurs in the caps 62/63 by communication through the purge tube 67. Therefore, ink is sucked and discharged from the nozzle openings 18 into the spaces defined by the caps 62/63. The discharged ink flows from the caps 62/63 into the pump 65 via the purge tube 67 and the inlet 65c of the pump 65. The ink is then stored in the space defined between the first piston 65d and the second piston 65e. When a predetermined amount of ink flows into the pump 65, negative pressure disappears. After a slight delay, the caps 62/63 are lowered below the plane of the platen 32 (see Fig. 4) by the cap raising/lowering portion 69, and the print heads 15/16 are kept uncovered.

[0097] After that, the first piston 65d and the second piston 65e are simultaneously moved to the right while the interval between the two pistons is kept constant. Therefore, during the movement of the pistons, the pressure in the space between the pistons remains constant, so that ink will not be sucked through the inlet 65c nor discharged therethrough back into the purge tube 67 or the caps 62/63. Then, the second piston 65e closes the inlet 65c, and the first piston 65d moves away from the outlet 65f and therefore opens the outlet 65f. The first piston 65d is then stopped while the second piston 65e is moved further rightward, so that the interval between the first piston 65d and the second piston 65e decreases and the capacity defined therebetween also decreases. Therefore, the waste ink stored in the pump 65 is pressurized and discharged via the outlet 65f. The discharged waste ink flows through the waste ink tube 66 and enters the waste ink reservoir 8b of the large ink cartridge 8. The first piston 65d and the second piston 65e are then moved together leftward, remaining substantially in contact with each other. The first piston 65d and the second piston 65e are stopped at such a position that the first piston 65d closes the outlet 65f and the second piston 65e closes the inlet 65c.

[0098] Finally, the protrusion (not shown) provided in a lower portion of the pump driving cam 64 is detected by the photosensor 68, and the end of the purge operation is indicated to the control unit 34. Then, the power transmission from the LF motor 31 to the pump driving gear 61 is discontinued by disengaging the LF motor gear 37, so that the pump driving cam 64 stops rotating at the initial position. The purge operation is thus completed.

[0099] The method of operating the portable printer 1 will be described with reference to Figs. 2 and 4. A cartridge member is set into the body frame 6, and the print heads 15/16 provided in the cartridge member is set on the carriage 27 provided in the printer body 3. When the power is turned on after the ink cartridges 8/9 have been set, the purge operation of sucking inks from the nozzle openings 18 to discharge dry ink or ink containing air bubbles or dust or the like before printing is started, in order to ensure good quality printing. As the initial position at the time of power-on, the nozzles 15a/16a of the print heads 15/16 are tightly covered with the caps 62/63. Therefore, drive power is transmitted from the LF motor 31 to the pump driving gear 61 via the LF motor gear 37 to perform the purge operation as shown in Fig. 7.

[0100] After that, the operation of the carriage 27 is checked, and the carriage 27 is stopped at the initial position for the start of printing. When an unused print sheet PP is inserted into the insert opening 22 of the portable printer 1, the print sheet PP is conveyed below the print heads 15/16 by the pressure roller 24 and the conveying roller 23 rotated by the LF motor 31. When the print sheet PP passes under the print heads 15/16 movable back and forth in the main scanning directions, that is, the direction of the arrow Y and the opposite direction, the print sheet PP is printed by inks ejected from the nozzles 15a/16a of the print heads 15/16.

[0101] The four color inks flow from the ink packages 8a/9a of the ink cartridges 8/9 into the corresponding ink extracting needles 10 put into the ink packages 8a/9a, via the extracting holes of the ink extracting needles 10. The inks flow from the ink extracting needles 10 into the four ink supply tubes 12 via the communication openings (not shown) of the coupling members 11. The inks are thus supplied into the print heads 15/16, so that the inks can be ejected from the nozzles 15a/16a of the print heads 15/16. After printing, the printed print sheet PP is discharged out of the sheet discharge opening 4 by the pressure roller 26 and the discharge roller 25 rotated by the LF motor 31

[0102] As described above, the print heads 15/16, set on the carriage 27 driven by the CR motor 30, perform printing by ejecting the inks from the nozzles 15a/16a while being moved back and forth in the lower space 1b of the portable printer 1 in the direction of the arrow Y in Fig. 2 and the opposite direction. As the print heads 15/16 set on the carriage 27 are reciprocated in this manner, the four ink supply tubes 12 connected to the upper portion of the print heads 15/16 are also moved back and forth. When the print heads 15/16 are moved into a right-side portion (right side in Fig. 2) of the lower space 1b of the portable printer 1, portions of the ink supply tubes 12 closer to the print heads 15/16 are curved. The curved portion (bent or folded portion) of the stack of the ink supply tubes 12 is supported by the partition 5a disposed in the upper space la of the portable printer 1. The ink supply tubes 12 are curved toward the connecting portion provided in the upper portion of the print heads 15/16 disposed in the upper space 1a of the portable printer 1.

[0103] The flushing operation is performed at the start and end of printing and at every elapse of about 10 seconds during printing, by withdrawing the print heads 15/16 into either one of the flushing areas.

[0104] After printing, the carriage 27 is stopped at a position over the caps 62/63, and then the purge operation is performed once by transmitting drive power from the LF motor 31 to the pump driving gear 61 via the LF motor gear 37. The caps 62/63 are raised and stopped to tightly cover the nozzles 15a/16a in order to prevent the nozzles 15a/16a from drying while the nozzles 15a/16a are left unoperated.

[0105] The operation of the large ink cartridge 8 will be described with regard to the ink packages 8a. The two ink packages 8a are disposed horizontally and housed in an upper portion of the large ink cartridge 8, so that ink is supplied from the ink packages 8a to the left-side print heads 16 via the ink supply tube 12 at equal height differences. The flexible resin laminate body has an appropriate elasticity, so that the laminate body will not be flattened by the atmospheric pressure, but will provide a suitable negative pressure on ink in the left-side nozzles 16a of the left-side print heads 16. Therefore, ink supply optimal to ink jet type print heads can be accomplished. The two ink packages 8a contain the black ink and the magenta ink in equal amounts in the beginning. The above-described purge operation consumes large amounts of inks. In the portable printer 1, in particular, which is used less frequently than desk-top printers, the ink consumption by the purge operation is great in comparison with the ink consumption by printing. All the inks are consumed equally by the purge operation. If the magenta ink package 8a is smaller than the other, the magenta ink will likely run out earlier than the black ink, so that the black ink remaining in the large ink cartridge 8 will be wasted. However, if the magenta ink and the black ink are stored in equal amounts in the large ink cartridge 8, the incidence of such undesired events will decrease.

[0106] The waste ink reservoir 8b provided in the large ink cartridge 8 will be described. Waste ink drawn by the pump during the purge operation is conveyed to the charging needle 70 via the waste ink tube 66, and injected from the tip end of the charging needle 70 into the first waste liquid chamber 83a of the waste ink reservoir 8b. The waste ink is absorbed into the absorber 87 disposed in an upper portion of the first waste liquid chamber 83a. If waste ink is further absorbed, waste ink is absorbed and diffused into the entire lower portion of the absorber 87 in the first waste liquid chamber 83a. Since the absorber 87 has many gaps therein, the absorber 87 is able to continue to absorb waste ink if waste is further injected. Since the first waste liquid chamber 83a has the protrusion 84 in its lower portion, waste ink absorbed into the absorber 87 is collected and stored at a lower portion of the protrusion 84 by gravity, so that the absorption capacity of the upper portion of the absorber 87 can be recovered.

[0107] Since the second waste liquid chamber 83b is separated from the first waste liquid chamber 83a by the partition 89, waste ink does not flow into the second waste liquid chamber 83b unless the level of waste ink rises to the vent hole 86 formed in the partition 89. If there is no partition between the first waste liquid chamber 83a and the second waste liquid chamber 83b and the absorbers are integrated, waste ink injected into the first waste liquid chamber 83a diffuses into the absorber 87 due to capillarity, and spreads in the entire absorber 87. Then, the waste ink absorbing rate of the absorber 87 decreases, so that ink may overflow toward the third waste liquid chamber 83c earlier than ink overflows in the case where separate waste ink chambers are provided. That is, since a waste ink chamber is divided into plurality of chambers and the absorbers 87 are separated from one another by partitions 89, the embodiment is able to hold increased amounts of inks while preventing overflow, without increasing the capacity of the waste ink chambers.

[0108] Similarly, the second waste liquid chamber 83b and the third waste liquid chamber 83c are separated from the third waste liquid chamber 83c and the fourth waste liquid chamber 83d, respectively, by the partitions 89 having the vent holes 86. Therefore, increased amounts of waste inks can be stored without increasing the capacity of the waste ink chambers.

[0109] When waste ink is injected into the first waste liquid chamber 83a, the pressure in the first waste liquid chamber 83a increases corresponding to the volume of waste ink injected, so that an amount of air corresponding to the volume of waste ink injected needs to be let out from the first waste liquid chamber 83a. In this case, it may be considered that air is released from a hole formed in the side wall of the fourth waste liquid chamber 83d via the vent holes 86 between the waste ink chambers. However, if pressurized air is released via the vent holes 86, waste ink may move along with air streams, which contradicts the intention to restrict movements of ink by providing the partitions 89. Furthermore, in some cases, waste ink remains in the relatively small-size second to fourth waste liquid chambers 83b-83d so that air passage may be impeded. In such cases, it can be considered that air pressurized by the amount of ink injected into the first waste liquid chamber 83a will jet out of the vent hole 86 formed in the side wall of the fourth waste liquid chamber 83d. In order to avoid such an undesired event, a waste ink absorber 87 is not provided in the space defined to the left of the first waste liquid chamber 83a, but a vent hole is formed in an upper portion of the partition 89. Since the vent holes are directed upward and formed at high positions, with no absorber provided nearby, the jetting of air with waste ink can be prevented. Furthermore, since an upper portion has a certain airtightness, waste ink is less likely to flow out of the upper portion even if the upper portion is slightly wet with waste ink.

[0110] If the absorber 87 is formed by a high-molecular absorber, the water absorption rate becomes very high. Furthermore, absorbed waste ink is fixed by the high-molecular absorber. Therefore, this construction effectively prevents an accident that waste ink leaks out of the large ink cartridge 8.

[0111] The setting of the amount of waste ink storable in the waste ink reservoir 8b to 24 mL in this embodiment will be described. The amount of ink stored in each of the ink packages 8a of the large ink cartridge 8 is 8 mL in this embodiment. Assuming that the amount of an ink remaining in the ink package 8a when another ink in the large ink cartridge 8 runs out after normal printing operation is 2 mL, the amount of the ink consumable for printing becomes 6 mL. If all the inks are entirely drawn by the purge operation and injected into the waste ink reservoir 8b, the total amount of waste ink drawn and injected into the waste ink reservoir 8b becomes 24 mL, that is, four times 6 mL, since the four inks are simultaneously drawn during the purge operation. Therefore, the capacity of the waste ink reservoir 8b of 24 mL is sufficient to prevent overflow. That is, when the total amount of waste ink stored in the waste ink reservoir 8b becomes 24 mL, a certain ink in the ink package 8a has substantially run out, so that the large ink cartridge 8 will be replaced. The circumstances are similar for replacement of the small ink cartridge 9. To describe more generally, the amount of waste ink storable in the waste ink reservoir, that is, a required capacity of the waste ink reservoir, is a quantity obtained by multiplying twice the amount of an ink stored in each ink package 8a of the large ink cartridge 8 that is consumable by the printing or purge operation, by two, which is the total number of ink cartridges.

[0112] The large ink cartridge 8 is replaced when one of the black ink or the magenta ink in the ink package 8a runs out. The large ink cartridge 8 can be detached by releasing the lid 7 shown in Fig. 1 and manually pulling the large ink cartridge 8 out in the direction indicated by arrow X in Fig. 2. A new large ink cartridge 8 is inserted in the direction opposing arrow X along the cartridge frame 5, so that the ink extracting needle 10 and the charging needle 70 contact and pierce the rubber film of the extraction opening 88 and the rubber film of the injection opening 85, respectively. The ink extracting needle 10 and the charging needle 70 are thus airtightly put through the rubber films of the extraction opening 88 and the injection opening 85. The attachment of the large ink cartridge 8 is completed by inserting the large ink cartridge 8 to a predetermined position.

[0113] The small ink cartridge 9 will now be described. Fig. 9 is a sectional view of the small ink cartridge 9 taken on line VII-VII in Fig. 7, viewed from the back side thereof (upper side in Fig. 7). Fig. 11 is a view of the small ink cartridge 9, viewed from above (upper side in Fig. 1). As shown in Figs. 9 and 11, the small ink cartridge 9 is substantially the same as the large ink cartridge 8, except that the small ink cartridge 9 does not have a waste ink reservoir 8b, and the capacity of the ink packages are different. Portions of the small ink cartridge 9 similar to those of the large ink cartridge 8 will not be described again.

[0114] The capacity of each ink package 9a of the small ink cartridge 9 is 5.5 mL. The reason for the smaller capacity compared with the capacity of each ink package 8a of the large ink cartridge 8, that is, 8 mL, is that the amount of the cyan or yellow ink used is less than the amount of the black or magenta ink used, which is empirically known. The aforementioned capacity settings for the ink packages 8a of the large ink cartridge 8 and the ink packages 9a of the small ink cartridge 9 substantially equalizes the replacement frequencies of the large ink cartridge 8 and the small ink cartridge 9. As mentioned in the description on the large ink cartridge 8, there are cases where the amount of an ink actually used for printing is less than the amount of the ink consumed for purging or flushing. In such cases, it may be considered that the cyan ink and the yellow ink are consumed at substantially equal rates. Therefore, since the cyan and yellow inks are contained in the single small ink cartridge 9 in this embodiment, the embodiment reduces the ink cartridge replacement frequency to about a half, in comparison with a construction in which separate ink cartridges are used to contain the cyan ink and the yellow ink.

[0115] The small ink cartridge 9 is horizontally disposed with its upper end being flush with the upper end of the large ink cartridge 8. The nozzles 15a/16a of the print heads 15/16 are horizontally arranged. Therefore, the supply of ink from the print heads 15/16 to the nozzles 15a/16a are performed based on the same height difference. Hence, the meniscuses formed in the individual nozzle openings 18 become uniform, so that the printing of the individual inks becomes uniform.

[0116] As described above, in the portable printer of the embodiment, the two print heads 15/16 are disposed side by side in a main scanning direction. The print heads 15 has two rows of nozzles 15a, that is, rows of nozzles for printing the black ink and the magenta ink. The print head 16 has two rows of nozzles 16a, that is, rows of nozzles for printing the cyan ink and the yellow ink. The inks supplied to the same head are purged or flushed simultaneously and in equal amounts. There are cases where the amount of an ink used for purging and flushing is considerably greater than the amount of the ink used for actual printing. Considering these factors, two color inks to be supplied to the same print head are contained in the same cartridge in equal amounts so that the two color inks in the cartridge will substantially simultaneously run out. Therefore, the portable printer of the embodiment reduces the cartridge replacement frequency, and substantially prevents undesired events that when an ink in a cartridge runs out, the other ink remains in the cartridge and is therefore wastefully discarded, while providing excellent print quality. These advantages are significant in portable printers, in which the nozzle recovery frequency is high.

[0117] While the invention has been described with the embodiment, it is to be understood that the invention is not restricted to the particular forms shown in the foregoing embodiment. Various modifications and alternations can be made thereto without departing from the scope of the invention.

[0118] Although the portable printer of the foregoing embodiment is a two-head type using the four color inks, that is, Y, M, C and K, the printer may be a 6-color 3-head type using special color inks, for example, a fluorescent color ink or the like, in addition to the four color inks. The printer may also be an 8-color 4-head type using, for example, light Y, light M, light C and light K inks in addition to the four color inks.

[0119] Although the embodiment is described above in conjunction with the ink jet print heads, the invention is applicable not only to ink jet heads but also to any type head as long as ink is ejected to a recording medium by a certain method. The invention is also applicable to thermal-transfer type printers.

[0120] As is apparent from the foregoing description, the ink cartridge according to the invention reduces the cartridge replacement frequency and reduces the production cost of the cartridges in comparison with a construction in which color inks are contained in respective ink cartridges. Furthermore, in comparison with a construction in which an ink cartridge contains many color inks, the ink cartridge of the invention reduces the amounts of inks to be wastefully discarded, reduces the incidence of replacement of ink cartridges, and reduces the operating cost.

[0121] Furthermore, the ink cartridge of the invention makes it possible to store color inks that are expected to be used in relatively great amounts into a particular ink cartridge, and store other color inks into another ink cartridge.

[0122] The ink cartridge of the invention reduces the incidence of an event that only one of the inks in an ink cartridge runs out while the other ink remains in a great amount, even if the purge operation is frequently performed.

[0123] Furthermore, the ink cartridge of the invention substantially equalizes the replacement frequencies of the ink cartridges, since black ink, that is expected to be consumed in great amounts, is contained in one of the ink cartridges that has a greater ink storing capacity.

[0124] Further, the ink cartridge of the invention is advantageously able to store waste ink produced as a result of the purge operation of the printing apparatus, into a waste ink reservoir. Therefore, it becomes unnecessary to separately prepare a container or the like for storing waste ink. Since the ink cartridge is replaced when the ink therein runs out, the waste ink is removed together with the ink cartridge. Therefore, the ink cartridge of the invention prevents an undesired event that waste ink overflows.

[0125] The ink cartridge of the invention makes it possible to form a vent hole for releasing an amount of air corresponding to an amount of waste ink injected into the waste ink reservoir, in a portion of an upper portion of the waste ink reservoir, the portion being closer to a storage device. Therefore, if ink leaks when air is released, ink moves toward the storage device, so that ink is less likely to leak out of the ink cartridge.

[0126] Further, the ink cartridge of the invention has a plurality of liquid chambers, so that if a large amount of waste ink is injected, ink will not enter the next liquid chamber until the first liquid chamber is filled with ink. Therefore, ink is further less likely to leak out.

[0127] The ink cartridge of the invention employs a waste ink absorbing member in a liquid chamber, thereby achieving an advantage that waste ink injected into the liquid chamber can be absorbed and stabilized by the waste ink absorbing member. Therefore, ink movements are restricted so as to prevent ink from leaking out.

[0128] Further, in the ink cartridge of the invention, the waste ink absorbing member is formed from a water-absorbing polymer, so that waste ink once absorbed into the absorbing member is fixed and, therefore, waste ink will not leak out.

[0129] Still further, in the ink cartridge of the invention, since the downward-protruded ink reservoir is provided, waste ink injected into this liquid chamber descends to a lower portion due to gravity, and therefore becomes stored in the protruded ink reservoir. Therefore, ink is prevented from moving into other liquid chambers, and leakage of waste ink to the outside is prevented.

[0130] Further, in the ink cartridge of the invention, the amount of waste ink never exceeds the amount of ink consumed for the purge operation even if the amount of ink consumed for the purge operation is far greater than the amount of ink used for the printing operation. Therefore, it never occurs that an amount of waste ink exceeding the capacity of the waste ink reservoir is injected thereinto. Therefore, an accident that waste ink overflows the waste ink reservoir and leaks out can be prevented.

[0131] Furthermore, the ink cartridge of the invention allows a weight reduction of the ink cartridge and therefore allows a weight reduction of the printing apparatus. The ink cartridge is able to supply ink in a favorable manner even if the ink cartridge is formed as a closed container having no vent hole to the outside. Therefore, leakage of ink to the outside can be prevented.

[0132] The ink cartridge of the invention makes it possible to provide an ink storage device separately from the print heads, in addition to the flexible liquid container. Therefore, the weight of the carriage can be reduced, and the load on the carriage motor (CR motor) is reduced. Hence, electric power consumption is reduced, and the weight and size of the motor and other devices can be reduced, and the head control precision can be improved. Furthermore, if a large amount of ink is stored into the storage device, the weight of the movable portion is not affected, so that it becomes possible to store a large amount of ink.

[0133] Further, the ink cartridge of the invention sets equal height differences between the ink storage device and the corresponding print heads, so that the hydraulic pressures on the heads due to the height differences become equal. Therefore, the meniscuses formed in nozzle openings of the heads become uniform, so that the ink cartridge achieves high-quality printing with good balance between the inks.

[0134] Further, if the ink cartridge of the invention is used together with an ink jet print head, particularly high-quality printing can be achieved.

Claims

1. An ink supplying apparatus for use in a printing apparatus capable of multi-color printing by using a plurality of color inks, comprising:

a plurality of ink cartridges each having storage devices that store a plurality of color inks.

2. The ink supplying apparatus according to claim 1, wherein the plurality of ink cartridges includes:

a first ink cartridge having a storage device that stores a plurality of color inks; and

a second ink cartridge having a storage device that stores a plurality of color inks other than the plurality of color inks stored in the first ink cartridge.

3. The ink supplying apparatus according to claim 2, wherein an amount of ink stored in the first ink cartridge is greater than an amount of ink stored in the second ink cartridge.

4. The ink supplying apparatus according to claim 2, wherein each ink cartridge is capable of storing the plurality of color inks in substantially the same amount.

5. The ink supplying apparatus according to claim 3, wherein one of the plurality of color inks stored in the first ink cartridge includes a black ink.

6. The ink supplying apparatus according to claim 3 or 5, wherein the first ink cartridge is provided with a waste ink reservoir.

7. The ink supplying apparatus according to claim 6, wherein the waste ink reservoir is disposed below the storage device of the first ink cartridge.

8. The ink supplying apparatus according to claim 6 or 7, wherein the waste ink reservoir has a plurality of liquid chambers that are separated by a partition having a communication hole.

9. The ink supplying apparatus according to claim 8, wherein the liquid chambers has a waste ink absorbing member.

10. The ink supplying apparatus according to claim 9, wherein the waste ink absorbing member is formed from a water-absorbing high-molecular material.

11. The ink supplying apparatus according to claim 8, 9 or 10, wherein at least one of the plurality of liquid chambers is provided with a portion protruded downward.

12. The ink supplying apparatus according to claim 11, wherein the portion protruded downward is provided with a waste ink absorbing member.

13. The ink supplying apparatus according to any one of claims 6 to 12, wherein the printing apparatus is an ink jet printing apparatus that has an ink jet head and performs printing by ejecting ink onto a recording medium and the waste ink is drawn from the ink jet head by a purge operation.

14. The ink supplying apparatus according to claim 13, wherein an amount of waste ink storable in the waste ink reservoir is at least an amount obtained by multiplying twice an amount of an ink stored in the first ink cartridge that is consumable by the printing apparatus, by a number of the ink cartridges.

15. The ink supplying apparatus according to any one of claims 2 to 14, wherein the storage device of each ink cartridge is a flexible liquid container.

16. The ink supplying apparatus according to claim 15, wherein the storage device of each ink cartridge is connected in communication to the print head via a flexible hollow tube.

17. The ink supplying apparatus according to claim 16, wherein the storage devices for the color inks in each ink cartridge are disposed so as to have substantially equal height differences relative to the print heads for ejecting the corresponding inks.

18. The ink supplying apparatus according to any one of claims 2 to 17, wherein the printing apparatus is an ink jet printing apparatus that has an ink jet head and performs printing by ejecting ink onto a recording medium.

19. The ink supplying apparatus according to any one of claims 2 to 18, wherein the first ink cartridge has a storage device that stores two color inks, and a second ink cartridge has a storage device that stores two color inks other than the two color inks stored in the first ink cartridge.

20. An ink jet printing apparatus capable of multi-color printing by using a plurality of color inks, comprising:

the ink supplying apparatus of any one of claims 2 to 19; and

an ink jet head that performs printing by ejecting ink to a recording medium.

Drawing