JP2011056792A - Moisturizing head cap for liquid ejecting head and liquid jetting apparatus - Google Patents

Abstract

To provide a moisture retaining head cap for a liquid discharge head, which has a barrier function and a function of mitigating fluctuations in internal pressure, has a simple structure, and has a low manufacturing cost.
An ink jet printer includes a moisturizing head cap that caps a nozzle group that is not capped by a suction head cap out of nozzle groups of an ink jet head. The moisturizing head cap 23 is manufactured by integrally molding a frame-shaped holder 26, a film 27 made of a thermoplastic elastomer, and a seal portion 28. Since the film 27 has low moisture permeability, even if the capping state is maintained for a long time, the viscosity increase rate of the ink in the nozzle does not increase so as to hinder the ink ejection. Further, the internal pressure fluctuation of the sealed space 30 formed by capping can be absorbed by the deformation of the film 27, and the internal pressure of the sealed space 30 can be kept constant.
[Selection] Figure 6

Description

  The present invention provides a moisture retention head cap for a liquid ejection head for suppressing the increase in the viscosity of the ink in the nozzle of the liquid ejection head mounted on a reciprocating carriage and holding the meniscus in the nozzle without destroying it, and The present invention relates to a liquid ejection apparatus including such a moisturizing head cap.

  In an inkjet printer having an inkjet head mounted on a reciprocating carriage, the carriage and inkjet head are returned to the home position at the left end of the carriage scanning area during standby, and the nozzle surface is sealed with a suction head cap for maintenance at this position. This suppresses the thickening of the ink in the nozzle. Here, in a structure in which two nozzle groups are provided in the inkjet head and these are arranged side by side in the carriage scanning direction, if two suction head caps are provided corresponding to the two nozzle groups, the suction mechanism and the ink recovery mechanism are respectively provided. Two systems are required, and the structure becomes complicated.

  Therefore, if a moisturizing head cap that seals the nozzle surface and does not perform suction is provided adjacent to the suction head cap, the two nozzle groups are sealed simultaneously to maintain a good ink state in the nozzles. While waiting. During maintenance, the carriage is scanned to move each nozzle group to a position facing the suction head cap, so that the two nozzle groups are sequentially sealed with one suction head cap to perform nozzle cleaning, flushing, etc. It can be carried out.

  In addition to a barrier function that prevents moisture from diffusing into the outside air, the head cap for moisture retention prevents the meniscus in the nozzle from being destroyed due to fluctuations in the internal pressure of the sealed space around the nozzle due to temperature changes during standby. In addition, it is desirable to have a function of reducing fluctuations in internal pressure. Patent Document 1 describes a print head cap system (moisturizing head cap) having a barrier function and an internal pressure fluctuation mitigating function. The cap system for a print head disclosed in Patent Document 1 is provided with a flexible diaphragm so as to face the nozzle surface, and a barrier portion having a hole communicating with outside air is provided outside the diaphragm. With this structure, the barrier portion prevents the moisture that has passed through the diaphragm from diffusing while relaxing the pressure fluctuation inside the cap due to the deformation of the diaphragm.

Japanese Patent No. 3342511

  The cap system for a print head disclosed in Patent Document 1 has a double structure in which a barrier portion is provided on the outside of the diaphragm. Therefore, the structure is complicated, the number of parts is large, and it takes time to assemble. There is a problem that can not be.

  In view of this point, an object of the present invention is to provide a moisture retention head cap for a liquid discharge head that has a barrier function and a function to alleviate internal pressure fluctuations, has a simple structure, and has a low manufacturing cost. The object is to propose a liquid ejection device having a head cap.

In order to solve the above problems, the present invention provides:
In the head cap for moisturizing the liquid discharge head configured to be able to form a sealed space that covers the nozzle surface side of the liquid discharge head and is blocked from the outside air,
It is characterized in that at least a part of the portion blocking the sealed space from the outside air is a flexible film facing the outside air.

  Since the present invention has a simple configuration in which the nozzle surface is cut off from the outside air by the flexible film, the number of parts is small and the manufacturing cost can be suppressed. In addition, since a decrease in internal pressure due to a temperature change or the like can be relieved by deformation of the film, the meniscus in the nozzle can be held without being destroyed. Furthermore, since a sealed space is formed around the nozzle surface, moisture diffusion to the outside air can be suppressed, and thickening of the liquid in the nozzle can be suppressed.

  In the present invention, it is desirable that the membrane has a moisture permeability lower than a preset value from the sealed space side to the outside air side. For example, if the range of the thickening rate of the liquid in the nozzle that can perform good discharge is set and the waiting time is assumed in advance, the state of the liquid in the nozzle within this thickening rate range It is good to set it to the moisture permeability which can maintain. In this way, the nozzle can be reliably maintained in a liquid dischargeable state under the assumed conditions.

  Further, it is desirable that the membrane has a deformability capable of absorbing a pressure difference between the sealed space and outside air and maintaining a constant internal pressure of the sealed space. For example, it is desirable to use a film having a deformability capable of maintaining a constant internal pressure by deformation of the film within a range of fluctuations in internal pressure caused by an assumed temperature change. In this way, under the assumed conditions, the internal pressure can be reliably maintained constant and can be maintained without destroying the meniscus in the nozzle.

  In the present invention, the portion facing the nozzle surface when the sealed space is formed is the film, and the distance between the film and the nozzle surface is closer to the nozzle surface when the internal pressure of the sealed space is reduced. It is desirable that the concave film is set to a minimum size as long as it does not interfere with the nozzle surface. For example, the distance between the nozzle surface and the membrane should be set so that the center portion of the most recessed membrane does not contact the nozzle surface when the membrane is recessed inside the sealed space in accordance with the assumed internal pressure drop. Good. In this way, the meniscus is not destroyed by contact between the membrane and the nozzle surface. In addition, if the membrane is made as close as possible to the nozzle surface as long as the membrane does not contact the nozzle surface during deformation, the volume of the sealed space can be reduced to the minimum necessary without changing the membrane area, and internal pressure fluctuations can be reduced. The accompanying volume change of the enclosed space is minimized. As a result, the required compliance (volume change amount per reference pressure) for mitigating the internal pressure fluctuation is reduced, and the internal pressure fluctuation can be mitigated even when a membrane having a small deformation amount per reference pressure is used.

  Further, in the present invention, a frame-like base material portion, the film closing the inner opening of the frame in the base material portion, and a seal rising in a direction perpendicular to the surface direction of the film along the outer periphery of the film And the sealing member is configured to be capable of forming the sealed space by pressing the seal portion against the outer peripheral portion of the nozzle surface. The part, the membrane, and the seal part may be integrally formed. For example, the seal part of the outer peripheral part of the film may be made of the same thermoplastic resin as the film, the base part may be made of another thermoplastic resin, and these may be integrally molded by two-color molding. In this way, the moisturizing head cap can be manufactured without performing complicated assembly work.

Next, the liquid ejection device of the present invention is
A liquid discharge head including a first nozzle group and a second nozzle group which are arranged adjacent to each other in the carriage scanning direction;
One of the first nozzle group and the second nozzle group is selectively sealed, and a negative pressure is formed around the sealed nozzle group so that liquid can be sucked from each nozzle. A suction head cap,
Of the first nozzle group and the second nozzle group, each of the above-described configurations configured to be able to seal the nozzle group on the side that is not sealed by the suction head cap when the liquid discharge head is at the home position. And a moisturizing head cap.

  According to the present invention, the two nozzle groups can be sealed and kept at the same time by such a configuration, so that the viscosity increase of the liquid in the nozzle can be suppressed and the meniscus in the nozzle can be held without being destroyed. it can. During maintenance, the carriage is scanned to move each nozzle group to a position facing the suction head cap, so that the two nozzle groups are sequentially sealed with one suction head cap to perform nozzle cleaning, flushing, etc. It can be carried out.

  In the present invention, the suction head cap and the moisturizing head cap are located at a position opposite to a home position of the liquid discharge head, and the moisturizing head cap is on the end side of the carriage scanning range, and the suction head A configuration in which the cap is disposed adjacent to the carriage scanning direction so as to be on the center side of the carriage scanning range can be employed. In this way, the nozzle sealed in the suction head cap can perform maintenance such as nozzle cleaning and flushing while the head is waiting. The maintenance of the nozzle sealed in the moisturizing head cap can be performed in the middle of moving the head from the home position to the discharge position. Therefore, it is not necessary to return the carriage to the home position side in order to perform pre-discharge flushing when returning from the standby state.

  According to the present invention, since the nozzle surface is a simple configuration that is blocked from the outside air by the film, the number of parts is small, and the manufacturing cost can be suppressed. In addition, since a decrease in internal pressure due to a temperature change or the like can be relieved by deformation of the film, the meniscus in the nozzle can be held without being destroyed. Furthermore, since a sealed space is formed around the nozzle surface, moisture diffusion to the outside air can be suppressed, and thickening of the liquid in the nozzle can be suppressed.

1 is an external perspective view of an ink jet printer to which the present invention is applied. It is a schematic perspective view of a printer mechanism part. It is a perspective view of a head maintenance unit. It is explanatory drawing which shows the operation position of the inkjet head, the head cap for suction, and the head cap for moisture retention seen from the printer front side. It is the perspective view and partial sectional view of a moisture retention head cap. It is explanatory drawing which shows the state which capped the nozzle surface of the inkjet head with the head cap for moisture retention.

  Hereinafter, an ink jet printer which is an embodiment of a liquid ejection apparatus of the present invention and a control method thereof will be described with reference to the drawings.

(Overall configuration of inkjet printer)
FIG. 1 is an external perspective view of an ink jet printer. An ink jet printer 1 (liquid ejection device) performs color printing on a long recording paper fed out from roll paper using a plurality of types of color inks, and includes a printer case 2 having a rectangular parallelepiped shape as a whole. An opening 3 for mounting a roll paper is formed at the center of the front surface of the printer case 2. The opening 3 is sealed by an opening / closing lid 5 to which a recording paper discharge guide 4 is attached at the upper end. A recording paper discharge port 6 is formed between the recording paper discharge guide 4 and the upper edge portion of the opening 3 of the printer case 2. When the lock (not shown) is released and a finger is placed on the recording paper discharge guide 4 and pulled forward, the opening / closing lid 5 can be opened from the closed position shown in the drawing to the open position that falls forward about the lower end.

  A power switch 7a, a paper feed switch 7b, a plurality of operation state display lamps 7c, and the like are arranged on the right side of the opening / closing lid 5 on the front surface of the printer case 2. A mounting port 8 a of an ink cartridge mounting portion 8 having a vertically long rectangular cross section extending in the front-rear direction of the printer is opened on the left side portion of the opening / closing lid 5 on the front surface of the printer case 2. Is installed. When a button (not shown) is operated, the lock is released, the ink cartridge 9 is pushed forward by the spring force, and the ink cartridge 9 can be pulled out.

  FIG. 2 is a schematic perspective view showing the printer mechanism unit 10 covered with the printer case 2 in the inkjet printer 1. A roll paper storage unit is formed in the center of the printer mechanism unit 10. When the opening / closing lid 5 is opened, the roll paper storage unit opens forward, and the roll paper can be replaced. On the upper side of the roll paper storage unit, a platen 12 is bridged in the printer width direction, and on the upper side of the platen 12, a carriage 14 equipped with an inkjet head 13 (liquid ejection head) with the nozzle surface facing downward is mounted. Has been placed.

  The carriage 14 is mounted with a diaphragm pump unit 16 including sub tanks 15a to 15d for storing inks of four colors of cyan, magenta, yellow, and black. The ink supplied from the diaphragm pump unit 16 to the inkjet head 13 is temporarily stored in each of the sub tanks 15 a to 15 d and then supplied to the in-head flow path of the inkjet head 13. One end of each of the flexible ink tubes 17a to 17d is connected to each of the sub tanks 15a to 15d. The other ends of the flexible ink tubes 17a to 17d are connected to four ink supply paths (not shown) extending in the vertical direction, which are arranged at the rear end portion of the ink cartridge mounting portion 8. . Each of the ink supply paths communicates with the ink cartridge 9 mounted on the ink cartridge mounting portion 8.

  The carriage 14 is shown by an imaginary line in FIG. 2 deviated to the left side of the platen 12 from the home position A indicated by a solid line in FIG. It can move to the left end position B shown. The ink jet printer 1 transports the recording paper fed from the roll paper by a recording paper transport mechanism (not shown) along the surface of the platen 12, and performs ink jet toward the recording paper while scanning the carriage 14 in conjunction with the transport operation. Printing on recording paper is performed by ejecting ink from the head 13.

(Head maintenance unit)
A head maintenance unit 20 is disposed at a position off the right side of the platen 12. FIG. 3 is a perspective view showing the head maintenance unit 20 taken out. The head maintenance unit 20 includes a unit case 21 having a rectangular parallelepiped shape that is elongated in the longitudinal direction of the printer as a whole. A head cap unit 24 including a suction head cap 22 and a moisturizing head cap 23 is disposed at the upper end of the front portion of the unit case 21. The suction head cap 22 and the moisturizing head cap 23 are arranged adjacent to each other in the printer width direction, that is, the carriage scanning direction, and open upward. A head cap raising / lowering mechanism (not shown) for raising and lowering these components is incorporated below the head cap unit 24.

  4A to 4D are explanatory views showing the operation positions of the inkjet head 13, the suction head cap 22, and the moisturizing head cap 23 as viewed from the front side of the printer. In the present embodiment, the suction head cap 22 of the two head caps is disposed near the center in the carriage scanning direction (printer width direction), and the moisturizing head cap 23 is near the end in the carriage scanning direction (close to the home position). Is arranged. The inkjet head 13 includes a pair of parallel nozzle groups 13A and 13B (first nozzle group and second nozzle group) extending in the front-rear direction of the printer.

  As shown in FIG. 4A, the head cap unit 24 is retracted below the height position of the nozzle surface of the inkjet head 13 when the carriage 14 is away from the home position A during a printing operation or the like. It is in position C. When the carriage 14 returns to the home position A, as shown in FIG. 4B, the nozzle surfaces of the nozzle groups 13A and 13B of the inkjet head 13 mounted on the carriage 14 are connected to the suction head cap 22 and the moisture retention. The head caps 23 face each other from above. In this state, the suction head cap 22 and the moisturizing head cap 23 are lifted from the retracted position C to suck the nozzle surfaces of the nozzle groups 13A and 13B of the inkjet head 13 as shown in FIG. The head cap unit 24 is positioned at the capping position D capped from below by the head cap 22 for moisture and the head cap 23 for moisture retention. In this state, since both the nozzle groups 13A and 13B are capped, the inkjet head 13 can be kept on standby in a state where the thickening of the ink in the nozzles due to drying is suppressed.

  A tube pump (not shown) and a motor for driving the tube pump (not shown) are incorporated in the rear portion of the head cap lifting mechanism in the unit case 21. At the capping position D in FIG. 4C, the tube pump is driven in a state where the suction head cap 22 is capped on the nozzle surface of the nozzle group 13A, whereby a negative pressure is applied to the sealed space formed by the suction head cap 22. The nozzle cleaning can be performed by sucking ink from each ink nozzle of the nozzle group 13A. Further, flushing can be performed by ejecting ink from each ink nozzle in a state where the suction head cap 22 is capped on the nozzle surface of the nozzle group 13A. The waste ink sucked or discharged is collected through a waste ink tube 25 into a waste ink storage portion in the ink cartridge 9 attached to the ink cartridge attachment portion 8.

  A tube pump and a waste ink tube 25 are not connected to the moisturizing head cap 23. Therefore, when performing nozzle cleaning or flushing of the nozzle group 13B, as shown in FIG. 4D, a maintenance position E in which the carriage 14 is moved from the home position A to the platen 12 side by the distance between the nozzle groups 13A and 13B. The nozzle group 13B is opposed to the suction head cap 22. Then, the head cap unit 24 is moved to the capping position D, and each nozzle surface of the nozzle group 13B is capped from below by the suction head cap 22 as shown in FIG. Thereby, nozzle cleaning or flushing of the nozzle group 13B can be performed.

(Moisturizing head cap)
5A is a perspective view of the moisturizing head cap 23, and FIG. 5B is a partial cross-sectional view thereof. The moisturizing head cap 23 has a frame-shaped holder 26 (base material portion) having a rectangular opening 26a (inner opening) formed in the center, and a uniform thickness covering and closing the opening 26a in the holder 26. A flexible membrane 27 is provided. The outer peripheral portion 27a of the film 27 extends over the upper end surface of the holder 26 surrounding the opening 26a, and is in close contact with the upper end surface. A rib-shaped seal portion 28 is formed along the outer peripheral edge of the outer peripheral portion 27a so as to rise in a direction intersecting the surface direction of the film 27 (in this embodiment, a direction orthogonal to the surface direction of the film 27). . The seal portion 28 forms an upward concave portion 29 on the upper surface of the moisturizing head cap 23.

  FIG. 6 is an explanatory cross-sectional view showing a state in which the nozzle surface of the inkjet head 13 is capped by the moisturizing head cap 23. The moisturizing head cap 23 is disposed in such a posture that the surface of the film 27 is opposed to the nozzle surface of the inkjet head 13 and the seal portion 28 is extended upward toward the nozzle surface. At the capping position D, the moisture retaining head cap 23 is in pressure contact with the outer peripheral portion of the nozzle surface of the nozzle group 13A or nozzle group 13B in the inkjet head 13 at the capping position D. Thereby, the inside of the upward concave portion 29 becomes a sealed space 30 surrounding the nozzle surface, and the sealed space 30 is blocked from the outside air by the film 27 and the seal portion 28. At this time, the entire lower surface of the film 27 is in direct contact with the outside air.

  In the moisturizing head cap 23, the part from the film 27 to the seal part 28 is formed of the same thermoplastic resin material, and the part of the holder 26 is formed of another thermoplastic resin material. The moisturizing head cap 23 is manufactured by integrally molding these two materials by two-color molding, so that the structure is simple and the number of parts is small. Therefore, it can be manufactured at low cost.

  The material forming the portions of the film 27 and the seal portion 28 is a thermoplastic elastomer having elasticity close to that of rubber. For example, an elastomer AR (styrene-based thermoplastic elastomer) that is a product of Aron Kasei Co., Ltd. is used. Can do. This thermoplastic elastomer has a very low moisture permeability. Therefore, it has a barrier property that allows the moisture in the sealed space 30 to be held without escaping outside for a long time even though the entire membrane 27 is in direct contact with the outside air. I have. In other words, this thermoplastic elastomer has a normal ink thickening rate in the nozzles in the sealed space 30 even when the moisture permeability of the film 27 remains in the capping state for a preset waiting time. It does not increase so much as to hinder the discharge.

  When the internal pressure in the sealed space 30 fluctuates due to a temperature change or the like, the membrane 27 is deformed to reflect the pressure difference from the outside air, thereby relaxing the internal pressure fluctuation. For example, when the internal pressure of the sealed space 30 is lower than the outside air, the membrane 27 is in a recessed state F (state of a broken line in FIG. 6) in which it is recessed toward the nozzle surface side, and the internal pressure fluctuation is alleviated. Further, when the internal pressure of the sealed space 30 rises higher than the outside air, the membrane 27 is in an expanded state G (indicated by a one-dot chain line in FIG. 6) swelled to the outside air side, and the internal pressure fluctuation is alleviated. In the present embodiment, the film 27 having a deforming function to such an extent that the internal pressure can be kept constant by deformation of the film 27 even when the internal pressure fluctuation within a range assumed in advance occurs.

  That is, the membrane 27 is formed so that the compliance (the amount of deformation per reference pressure) of the membrane 27 is larger than the required compliance (volume change amount per reference pressure) for absorbing the internal pressure fluctuation within the range assumed in advance. Therefore, characteristics such as film thickness, film plane shape, and Young's modulus are determined so as to obtain a deformation amount per reference pressure that satisfies this standard.

  In the moisturizing head cap 23, the height of the seal portion 28 is determined so that the distance between the nozzle surface and the film 27 in the capping state is as small as possible in the range where the film 27 does not interfere with the nozzle surface in the recessed state F. Thus, the volume of the sealed space 30 is configured to be as small as possible. By making the sealed space 30 small, the volume fluctuation amount when the internal pressure fluctuates can be reduced, so that the required compliance can be reduced. Therefore, even if the membrane 27 having a small deformation amount per reference pressure is used, it is possible to reduce the internal pressure fluctuation.

(Other embodiments)
The above embodiment is an example in which the present invention is applied to the control method of the ink jet printer 1, but the present invention can also be applied to other liquid ejecting apparatuses that eject liquid other than ink. For example, it can also be applied to liquid ejection devices for ejecting reagent solutions and liquid samples from liquid ejection heads, and liquid ejection devices for ejecting liquid paints and liquid materials from liquid ejection heads and applying them by printing It is.

(Modification example)
In the above embodiment, the concave portion 29 of the moisturizing head cap 23 is formed in a shallow rectangular dish shape so that the flexible film 27 faces the nozzle surface of the inkjet head 13 during capping (bottom part of the dish). Although provided, the shape of the concave portion 29 of the moisturizing head cap 23 is not limited to a rectangular dish shape, and may be formed in a polygonal or elliptical dish shape. Alternatively, the portion facing the nozzle surface of the inkjet head 13 may be a curved surface, and all or part of the curved surface may be the flexible film 27. Or you may make the side part which does not oppose the nozzle surface of the inkjet head 13 into a flexible film | membrane form.

DESCRIPTION OF SYMBOLS 1 ... Inkjet printer (liquid discharge apparatus), 2 ... Printer case, 3 ... Opening part, 4 ... Recording paper discharge guide, 5 ... Opening / closing lid, 6 ... Recording paper discharge port, 7a ... Power switch, 7b ... Paper feed switch, 7c: Operation status display lamp, 8: Ink cartridge mounting portion, 8a ... Mounting port, 9 ... Ink cartridge, 10 ... Printer mechanism, 12 ... Platen, 13 ... Inkjet head (liquid ejection head), 13A ... Nozzle group (first) No. 1 nozzle group), 13B ... Nozzle group (second nozzle group), 14 ... Carriage, 14a ... Carriage guide shaft, 15a-15d ... Sub tank, 16 ... Diaphragm pump unit, 17a-17d ... Flexible ink tube, 20 ... Head maintenance unit, 21 ... Unit case, 22 ... Suction head cap, 23 ... Moisturizing Head cap, 24 ... head cap unit, 25 ... waste ink tube, 26 ... holder (base material), 26a ... opening, 27 ... film, 27a ... outer peripheral portion, 28 ... sealed portion, 29 ... concave, 30 ... sealed space A: Home position, B: Left end position, C: Retraction position, D: Capping position, E: Maintenance position, F: Recessed state, G ... Inflated state

Claims (7)

In the head cap for moisturizing the liquid discharge head configured to be able to form a sealed space that covers the nozzle surface side of the liquid discharge head and is blocked from the outside air,
A moisturizing head cap for a liquid discharge head, wherein at least a part of a portion blocking the sealed space from outside air is a flexible film facing the outside air. In claim 1,
A moisture retention head cap for a liquid discharge head, wherein the film has a moisture permeability from the sealed space side to the outside air side lower than a preset value. In claim 1 or 2,
The moisturizing head cap for a liquid discharge head, wherein the film has a deformability capable of absorbing a pressure difference between the sealed space and outside air to maintain a constant internal pressure in the sealed space. In any one of claims 1 to 3,
The portion facing the nozzle surface when forming the sealed space is the film,
The distance between the film and the nozzle surface is set to a minimum dimension within a range in which the film recessed on the nozzle surface side does not interfere with the nozzle surface when the internal pressure of the sealed space decreases. Moisturizing head cap for liquid discharge head. In any one of claims 1 to 4,
A frame-shaped base part;
The film covering and closing the opening part surrounded by the frame in the base material part;
A seal portion that rises in a direction perpendicular to the surface direction of the film along the outer periphery of the film;
The sealed space can be formed by making the film face the nozzle surface of the liquid discharge head and pressing the seal portion against the outer peripheral portion of the nozzle surface,
A head cap for moisture retention of a liquid discharge head, wherein the base material portion, the film, and the seal portion are integrally formed. A liquid discharge head including a first nozzle group and a second nozzle group which are arranged adjacent to each other in the carriage scanning direction;
One of the first nozzle group and the second nozzle group is selectively sealed, and a negative pressure is formed around the sealed nozzle group so that liquid can be sucked from each nozzle. A suction head cap,
2. The nozzle group that is not sealed by the suction head cap when the liquid ejection head is at a home position among the first nozzle group and the second nozzle group is configured to be sealable. A liquid ejecting apparatus comprising the moisturizing head cap according to any one of Items 5 to 5. In claim 6,
The suction head cap and the moisturizing head cap are located at a position opposite to the home position of the liquid ejection head, the moisturizing head cap is at the end of the carriage scanning range, and the suction head cap is carriage scanned. A liquid ejecting apparatus, wherein the liquid ejecting apparatus is arranged adjacent to each other in the carriage scanning direction so as to be in the center of the range.

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