EP3323618B1

EP3323618B1 - Liquid discharge apparatus

Info

Publication number: EP3323618B1
Application number: EP17200648.8A
Authority: EP
Inventors: Yuusuke MATSUKI; Yoichi Kawabata
Original assignee: Ricoh Co Ltd
Current assignee: Ricoh Co Ltd
Priority date: 2016-11-21
Filing date: 2017-11-08
Publication date: 2021-04-14
Anticipated expiration: 2037-11-08
Also published as: EP3323618A1

Description

BACKGROUND

Technical Field

Aspects of the present disclosure relate to a liquid discharge apparatus.

Related Art

When thermocurable or photocurable ink is used in a liquid discharge apparatus, a problem occurs in that a maintenance unit that maintains a nozzle face of the liquid discharge head becomes clogged and stops functioning.
To solve such a problem, there is a liquid discharge apparatus using a photocurable ink as a liquid to be discharged in which a light-shielding part capable of blocking light from a light source is provided (see, for example, JP-2014-168912-A ).
In the apparatus described in JP-2014-168912-A , a wiper is stored under the light-shielding part. Thus, it is necessary to lower a carriage to a position of the wiper during wiping of the nozzle face. However, with such a configuration, the carriage may interfere (collide) with the light-shielding part when the carriage descends. The interference (collision) particularly easily occurs when the apparatus includes a large carriage mounting a plurality of recording heads. If the carriage and the light-shielding part collide with each other in such a state, the wiping process may not be performed.
Accordingly, it is an object of the present disclosure to provide a liquid discharge apparatus capable of reducing a size of a device while preventing a collision of a carriage with a cover for protecting a wiper.
US 6312093 B1 discloses an inkjet printing apparatus, including a carriage movable in a horizontal direction carrying inkjet heads, and a cleaning device with a blade to wipe and clean the inkjet heads.
US 5055861 A discloses an inkjet printing apparatus which includes an inkjet head rotatable between a cleaning position and a printing position, and a movable cleaning unit to maintain the inkjet heads.

SUMMARY

The invention is defined in the claims.
According to the present embodiment including the cover that protects the wiper, the present embodiment can reduce the size of the apparatus while preventing the carriage to interfere with the wiper.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view of an overall configuration of a liquid discharge apparatus seen from a front side of the liquid discharge apparatus;
FIG. 1B is a perspective view seen from a rear side of the liquid discharge apparatus;
FIG. 2 is a schematic top view of a wiper unit of a maintenance unit of the liquid discharge apparatus according to an embodiment;
FIG. 3 is a schematic side view of the wiper unit, a liquid discharge head, and a carriage of the liquid discharge apparatus along a sub-scanning direction (Y-direction) according to the present embodiment;
FIG. 4 is a schematic side view of the wiper unit, the liquid discharge head, and the carriage of the liquid discharge apparatus along the sub-scanning direction (Y-direction) according to the present embodiment;
FIG. 5 is a schematic side view of the wiper unit, the liquid discharge head, and the carriage of the liquid discharge apparatus along the sub-scanning direction (Y-direction) according to the present embodiment;
FIG. 6 is a flowchart of an example of a process of storing the wiper after a wiping process;
FIG. 7 is a functional block diagram of a controller;
FIGS. 8A and 8B illustrate a process of discharging a liquid onto a recording medium;
FIGS. 9A and 9B illustrate a process of discharging a liquid onto the recording medium;
FIG. 10 is a schematic side view of the wiper unit, the liquid discharge head, and the carriage of the liquid discharge apparatus along the sub-scanning direction according to the present embodiment;
FIG. 11 is a schematic side view of a main part of the liquid discharge apparatus along the main-scanning direction (X-direction) according to the present embodiment; and
FIG. 12 is a schematic top view of a main part of the liquid discharge apparatus according to the present embodiment.

DETAILED DESCRIPTION

A liquid discharge apparatus according to an embodiment of the present disclosure is described with reference to the accompanying drawings.
The liquid discharge apparatus includes a liquid discharge head that discharges liquid from nozzles, a carriage to mount the liquid discharge head to move horizontally and vertically, and a maintenance unit to maintain the liquid discharge head.
FIG. 1A is a perspective view of an overall configuration of a liquid discharge apparatus seen from a front side of the liquid discharge apparatus.
FIG. 1B is a perspective view seen from a rear side of the liquid discharge apparatus.
The liquid discharge apparatus 10 includes a carriage 12 and a stage 13 on which a recording medium 14 is placed. The liquid discharge apparatus 10 includes a carriage 12 that is an inkjet type carriage having a plurality of liquid discharge heads 11 provided with a plurality of nozzles 11n as illustrated in FIG. 12. The plurality of liquid discharge heads 11 discharges liquid from nozzles 11n to record dots on the recording medium 14. The nozzles 11n are formed on a nozzle face 11a of the liquid discharge heads 11 facing the stage 13. In this embodiment, a liquid having ultraviolet curable characteristic is used as an example.
An irradiator 33 is provided on a surface of the carriage 12 facing the stage 13. The irradiator 33 includes a light source for irradiating ultraviolet rays on the recording medium 14 on the stage 13. The irradiator 33 irradiates a light having a wavelength that cures the liquid discharged from the nozzles 11n.
A guide rod 19 bridges a left side plate 18a and a right side plate 18b. The guide rod 19 holds the carriage 12 so that the carriage 12 moves in an X-direction (main-scanning direction) as indicated by arrow X in FIG. 1A. Further, the carriage 12, the guide rod 19, and the side plates 18a and 18b form a single unit movable in a Y-direction (sub-scanning direction) as indicated by arrow Y in FIG. 1A along a guide rail 29 provided at a lower portion of the stage 13. The carriage 12 is movable in a Z-direction (vertical direction) as indicated by arrow Z in FIG. 1A.
That is, the carriage 12 of the liquid discharge apparatus 10 is capable of scanning in the X-direction and the Y-direction, as well as being able to move up and down in the Z-direction (vertical direction).
FIG. 2 is a schematic top view of a wiper 21 of a maintenance unit 50 and FIGS. 3 through 5 are schematic side views of the maintenance unit 50.
The maintenance unit 50 includes a wiper 21, a conveyor 40, and a light-blocking cover 30 (hereinafter also referred to as a "cover"). The wiper 21 wipes a nozzle face 11a of the liquid discharge head 11. The conveyor 40 includes a conveyor belt 22 and a motor 23. The conveyor 40 reciprocally moves the wiper between a retracted position and a wiping position. The wiper 21 is covered by a cover portion 31 of the cover 30 at the retracted position, and the wiper 21 wipes the liquid discharge head 11 at the wiping position. The cover 30 covers the wiper 21 at the retracted position and is vertically movable.
The cover 30 contacts the descending carriage 12 after the wiper 21 moves from the retracted position to the wiping position. The cover 30 then moves downward by being pushed down by the carriage 12.
The cover 30 is disposed in a region where the wiper 21 does not wipe the nozzle face 11a of the liquid discharge head (recording head) 11. When the wiper 21 wipes the nozzle face 11a at the wiping position, the cover 30 comes into contact with the descending carriage 12 and moves downward as it is pushed down by the carriage 12.
The liquid discharge apparatus 10 according to the present embodiment further includes a controller 100 for controlling driving of the carriage 12 and a conveyor 40. The controller 100 moves the carriage 12 downward after driving the conveyor 40 to move the wiper 21 from the retracted position to the wiping position. Then, the controller 100 drives the conveyor 40 to wipe the nozzle face 11a of the liquid discharge head 11 with the wiper 21 in a state where the cover 30 is pressed down by the descending carriage 12.
FIG. 2 is a schematic top view of the wiping unit 20.
By driving a motor 23 mounted on the wiping unit 20, the conveyor belt (rubber belt) 22 of an outer frame rotates, and the wiper 21 moves in the directions indicated by arrow D1 between the retracted position and the wiping position. When the wiper 21 moves to the vicinity of the left end portion (retracted position) in FIGS. 2 and 3, the wiper 21 is stored in a lower portion of the cover portion 31 of the cover 30. Thus, the cover 30 can cover and protect the wiper 21.
FIGS. 3 through 5 are schematic side views of the wiping unit 20, the liquid discharge head 11, and the carriage 12 along the Y-direction (sub-scanning direction of the carriage 12).
FIG. 3 illustrates a state in which the wiper 21 is in the retracted position and the wiper 21 does not wipe the nozzle face 11a of the liquid discharge head 11 (hereinafter also referred to as "at rest").
FIG. 4 illustrates a state in which the wiper 21 has moved from the retracted position to the wiping position.
FIG. 5 illustrates a state in which the wiper 21 is at the wiping position and wipes the nozzle face 11a of the liquid discharge head 11 (hereinafter also referred to as "wiping time").
In FIGS. 3 and 5, the motor 23 rotates in a direction indicated by an arrow R4, and accordingly, the conveyor belt 22 rotates in directions indicated by arrows R1, R2, and R3. Thereby, the wiper 21 moves in a direction indicated by an arrow D1 or D4. Further, by reversing a rotational direction of the motor 23, the wiper 21 is conveyed in a reverse direction. That is, as illustrated in FIG. 4, when the motor 23 rotates in a direction indicated by an arrow R8, the conveyor belt 22 rotates in a direction indicated by arrows R5, R6 and R7. Accordingly, the wiper 21 moves in a direction indicated by an arrow D5.
As illustrated in FIG. 3, the carriage 12 can be raised and lowered in a direction (vertical direction) indicated by an arrow D2 by driving a motor 28 for moving a carriage. The cover 30 is also movable in a direction indicated by an arrow D3 (vertical direction).
An elastic member 32 for urging the cover 30 in an upward direction is provided in the cover 30. Thus, the cover 30 moves downward by being pushed down by the carriage 12 in accordance with a downward movement of the carriage 12. The cover 30 moves upward when a pressing force on the cover 30 is released such as by a re-upward movement of the carriage 12.
At rest, the wiper 21 is conveyed in the direction indicated by the arrow D1 or D4 to reach the lower portion of the cover portion 31 of the cover 30 and is stored in cover 30. Therefore, the wiper 21 is shielded and protected by the cover 30 from light irradiated by the irradiator 33.
At the wiping time, the wiper 21 is first conveyed to a location under the liquid discharge head 11 as illustrated in FIG. 4 (right end part in FIG. 4) from the retracted position as illustrated in FIG. 3 in a direction indicated by the arrow D5 in FIG. 4 by the rotation of the motor 23 in the direction indicated by the arrow R8.
Next, as illustrated in FIG. 5, the cover 30 is pushed down and moves downward as indicated by the arrow D3 by the carriage 12 descending in the direction indicated by the arrow D2. The wiper 21 is exposed outside the cover 30 and is in a state capable of wiping the nozzle face 11a of the opposing liquid discharge head 11. After completion of wiping process, the carriage 12 is released from pressing the cover 30 with the upward movement of the carriage 12. Accordingly, the cover 30 also moves upward so that the wiping unit 20 can store the wiper 21 in the cover 30 as illustrated in FIG. 3.
As described above, the cover 30 covers the wiper 21 to prevent hardening of the liquid (ink) adhering to the wiper 21 while the wiper 21 is at rest. On the other hand, the wiper 21 is moved to the wiping position at wiping time. Therefore, the wiper 21 is not damaged by the downward movement of the cover 30 although the cover 30 is contacted and pressed by the carriage 12.
Particularly, when the carriage 12 is upsized such as by mounting a plurality of liquid discharge heads 11, the carriage 12 and the cover 30 may easily interfere with each other. Thus, the above-described configuration is effective to avoid interference between the carriage 12 and the cover 30.
On the other hand, in order to avoid interference between the carriage 12 and the cover 30, the cover 30 may be disposed away from the carriage 12 (disposed in the direction of D1 or D4 in FIGS. 3 and 5). In that case, a movement distance of the wiper 21 should be large, which complicates the structure of the liquid discharge apparatus 10 and also increases the size of the liquid discharge apparatus 10. The configuration of the above-described present embodiment can downsize the liquid discharge apparatus 10 since a moving distance of the wiper 21 is about the same as the moving distance of a conventional device.
Here, the irradiator 33 may irradiate the wiper 21 with light when the liquid discharge head 11 is raised when the wiper 21 is at the wiping position as illustrated in FIG. 5. Therefore, it is preferable to raise the carriage 12 and store the wiper 21 by the procedure illustrated in FIG. 6. FIG. 6 is a flowchart illustrating an example of a process of storing the wiper 21 after the completion of the wiping process of the wiper 21.
As illustrated in FIG. 5, the carriage 12 is raised to a range (first position) where contact of the carriage 12 and the cover 30 is secured (S102) from a state where the wiper 21 wipes the nozzle face 11a of the liquid discharge head 11 and ends (completes) the wiping process (S101). Next, the wiper 21 is moved in the D4 direction and housed in a lower part of the cover 30 (S103). Then, the carriage 12 is raised to a position before the carriage 12 is moved downward (S104). The above-described processes can avoid the irradiator 33 to irradiate the light to the wiper 21.
The operation of each parts including the carriage 12 and the conveyor 40 is performed by the controller 100 provided in an apparatus body of the liquid discharge apparatus 10. The controller 100 includes, for example, a control substrate on which a storage device such as a central processing unit (CPU) 101, a read only memory (ROM) 103, a random access memory (RAM) 102 or the like is mounted. The controller 100 may include a dedicated device, for example. The controller 100 controls the above-described operation by controlling the motor 23 and a motor 28 for elevating the carriage 12.
FIG. 7 is a functional block diagram of the controller 100. As illustrated in FIG. 7, the controller 100 includes the CPU 101, the RAM 102, the ROM 103, a hard disk drive (HDD) 104, a first motor controller 105, and a second motor controller 106.
The CPU 101 is a control mechanism that governs overall operational control of the controller 100. The CPU 101 controls the overall operation of the controller 100 by reading and executing a control program, for example, stored in the ROM 103.
The RAM 102 is a storage medium used as a work area at the time of execution of the control program executed by the CPU 101.
The ROM 103 and the HDD 104 are storage media that store the above-described control program and the like.
The first motor controller 105 controls the motor 23 for controlling a movement of the wiper 21. The first motor controller 105 controls the movement of the wiper 21 between the retracted position and the wiping position by controlling the drive the motor 23.
The second motor controller 106 controls the motor 28 for elevating the carriage 12. The second motor controller 106 controls the vertical movement of the carriage 12 by controlling the drive the motor 28.
The configuration and the form of the controller 100 are not particularly limited. An encoder sensor and an encoder slit, for example, may be mounted on the wiping unit 20 to make a position of the wiper 21 and the carriage 12 readable.
A mounting position of the cover 30 on the wiping unit 20 is not particularly limited as long as the cover 30 can store the wiper 21 while the wiper 21 is at rest and is movable in the vertical direction as described above.
Although a coil spring is illustrated as an example of the elastic member 32 in FIG. 3, the elastic member 32 is not limited to the coil spring as long as the elastic member 32 is capable of biasing the cover 30 upward.
A driving force of a downward movement of the cover 30 is not limited to the descending carriage 12. For example, the cover 30 may be moved by being pressed against the relatively lowered carriage 12 as the wiping unit 20 rises. Further, the cover 30 may be pressed and moved by simultaneously performing a descent of the carriage 12 and the lifting of the wiping unit 20.
The cover 30 may be configured to be movable in the vertical direction by a driver such as a motor. In this case, an embodiment becomes possible in which the cover 30 descends itself before the cover 30 contacts and is pushed by the descended carriage 12.
In the present embodiment, the cover 30 is described as "light-blocking cover 30" since the photocurable ink is used as the liquid to be discharged. However, usage of a cover in the liquid discharge apparatus of the present embodiment is not limited to blocking light. For example, the cover may be applied to an embodiment that uses liquid thermosetting ink or liquid which does not require light irradiation for curing.
The liquid discharged in the liquid discharge apparatus in the present embodiment has stimulative curability. The stimulus is, for example, light (ultraviolet, infrared, etc.), heat, or electricity, etc. For example, a liquid that is cured by light may be used. Specifically, a photocurable ink cured by light irradiation may be used as the liquid to be discharged. Further, a UV (ultraviolet) light source (irradiator 33 as illustrated in FIG. 1) is an example of a means for hardening (curing) the liquid with light.
Next, as an example of the liquid discharge apparatus according to the present embodiment, a liquid discharge apparatus that discharges a photocurable ink is described.
A recording technology in the liquid discharge apparatus has a feature that image recording can be performed in a non-contact state on a recording medium. By non-contact printing, it is possible to record on not only smooth media such as paper and film but also on media having uneven surface or thick media. Therefore, such liquid discharge apparatuses have been introduced to various industrial fields in recent years.
Non-contact printing is enabled by a technology that discharges ink droplets from a liquid discharge head (recording head). As a principle of discharge, an arbitrary ink droplet is jet from a microscale nozzle by pressing a liquid chamber in the liquid discharge head with electrical or thermal energy. A target image cannot be obtained if problem occurs in any one of the above-described members of the liquid discharge head because each member of the liquid discharge head cooperates with each other to discharge the ink droplets. Further, even if ink droplets are discharged, the target image cannot be obtained unless the ink droplets are accurately landed on the recording medium.
Regarding landing of ink droplets on the recording medium, a particularly important factor is a distance (gap) between the liquid discharge head (recording head) and the recording medium. A measure to solve a problem of a defect in a recorded image due to disturbance of this gap is described with reference to FIG. 8.
FIGS. 8A and 8B are side views of the liquid discharge apparatus 10. As illustrated schematically in FIGS. 8A and 8B, a recording medium 14 is placed on the stage 13, and the ink droplets 15 are ejected from the liquid discharge head (recording head) 11 in a direction indicated by an arrow 15a with respect to the recording medium 14.
It is preferable that the gap g1 from the liquid discharge head 11 to the recording medium 14 remains constant. The optimum value of the gap g1 from the liquid discharge head 11 to the recording medium 14 is determined according to an applied ink and a characteristic value of the liquid discharge head 11. Thus, it is difficult for the user to change the optimum gap according to the liquid discharge apparatus 10.
The gap g1 from the liquid discharge head 11 to the recording medium 14 varies according to a thickness t of the recording medium 14. Thus, the liquid discharge apparatus 10 preferably includes a system to lift the carriage 12 by an amount corresponding to the thickness t.
For example, a height of the carriage 12 in a case of printing the recording medium 14 having a thickness t1 of 1 mm in FIG. 8A is taken as a reference.
Then, when the recording medium 14 having a thickness t2 of 30 mm in FIG. 8B is printed, the height of the carriage 12 is raised by 29 mm (move in a direction indicated by an arrow D2) from the height of the carriage 12 in FIG. 8A. Thereby, the present embodiment can maintain the gap g1 constantly and obtain an image of same quality.
In order to make the gap g1 constant as described above, the liquid discharge apparatus 10 preferably includes a detector 17 to detect a thickness t1 of the recording medium 14 to which the liquid is discharged. The liquid discharge apparatus 10 preferably adjusts a lifting distance of the carriage 12 according to a read result from the detector 17. FIGS. 9A and 9B illustrate an example of the liquid discharge apparatus 10 with the detector 17.
FIGS. 9A and 9B are side views of the liquid discharge apparatus 10. As illustrated schematically in FIGS. 8A and 8B, a recording medium 14 is placed on the stage 13, and the ink droplets 15 are discharged from the liquid discharge head (recording head) 11 in a direction indicated by an arrow 15a with respect to the recording medium 14.
FIG. 9A illustrates an example in which the carriage 12 is positioned at an excessively high position with respect to the thickness t1 (= 1 mm) of the recording medium 14. When the ink droplets 15 are discharged from the nozzles 11n of the liquid discharge head 11 in the direction indicated by the arrow 15a without adjusting the gap g2, the ink droplets 15 become ink mist 16 in the air before landed on the recording medium 14. Thus, the discharged ink droplets 15 that become the ink mist 16 do not contribute to an image formation on the recording medium 14.
The ink droplets 15 that become the ink mist 16 in the air adhere to an unspecified portion in the liquid discharge apparatus 10 and are cured (hardened) and fixed to the unspecified portion with irradiation light irradiated by the irradiator 33. When the ink droplets 15 are adhered to the recording medium 14, the quality of the image on the recording medium 14 deteriorates. If the ink droplets 15 are adhered to a member of the liquid discharge apparatus 10, the ink droplets 15 may cause a failure of the liquid discharge apparatus 10.
On the other hand, in FIG. 9B, the liquid discharge apparatus 10 lowers the height of the carriage 12 in the direction indicated by the arrow D2. Thus, the gap g2 is adjusted to the gap g1 according to readings from the detector 17 that detects the thickness t1 of the recording medium 14.
In the example of FIG. 9B, an image of desired quality can be formed on the recording medium 14 by adjusting a position (height) of the carriage 12 to obtain the optimum gap g1.
A device that irradiates a laser beam to an object and calculates a distance from light reflected from the object may be used as the detector 17. The present embodiment mounts the detector 17 using a laser beam reflection is mounted. However, a type of the detector 17 is not particularly limited as long as the detector 17 can detect the thickness of the recording medium 14. For example, the detector 17 may include a detection part that contacts the recording medium 14 and measuring the thickness of the recording medium 14 with a physical return amount.
The liquid discharge apparatus according to the present embodiment preferably raise the wiping unit 20 for a distance identical to a raised distance of the carriage 12. Even if the carriage 12 is raised and lowered in accordance with the thickness of the recording medium 14 and an image is formed on the recording medium clearly, the wiper 21 cannot wipe the nozzle face 11a unless the wiping unit 20 is at the same height with the nozzle face 11a. If the height of the wiping unit 20 does not fluctuate, the carriage 12 needs to return to an original position for every image formation process that increases a waste of operation.
As illustrated in FIG. 10, the liquid discharge apparatus 10 of the present embodiment preferably includes a height adjuster 24 capable of adjusting a mounting position of the wiper 21 in the vertical direction.
FIG. 10 is a schematic side view of the wiping unit 20, the liquid discharge head 11, and the carriage 12 of the liquid discharge apparatus 10 along the Y-direction (sub-scanning direction) according to the present embodiment similar to FIGS. 3 through 5.
In order to always wipe the nozzle face 11a of the liquid discharge head 11 by the wiper 21 in the best condition, the height adjuster 24 adjusts the mounting position of the wiper 21 in the vertical direction to adjust the height of the wiper 21.
A first factor that requires the height adjustment is due to distortion of the wiper 21 (wiper blade) over time. If the wiping portion of the wiper 21 is made of rubber or a special polymer, a distortion in the vertical direction occurs in the wiper 21 by wiping the nozzle face 11a of the liquid discharge head 11 while applying a constant pressure on the nozzle face 11a by the wiper 21.
In the liquid discharge apparatus 10 mounting a plurality of liquid discharge heads 11, the distortion generated in the plurality of wipers 21 corresponding to each of the liquid discharge head 11 is not identical. Thus, the wiping efficiency also differs for each of the plurality of wipers 21. In order to enable a uniform wiping operation, a mechanism for adjusting the height of the wiper 21 is required. Even if there is only one liquid discharge head 11, a mechanism for adjusting the height of the wiper 21 that changes over time is necessary.
A second factor that requires height adjustment of the wiper 21 is dispersion in height in the initial state.
Since a position where the wiping unit 20 is in contact with the liquid discharge head 11 is not necessarily the same at the time of assembling the liquid discharge apparatus 10, it is necessary to adjust the height of the wiper 21 in order to make a biting amount of the wiper 21 into the liquid discharge head 11 constant.
By adjusting the height of the wiper 21, it is possible to avoid wiping accompanying excessive pressing of the wiper 21 on the liquid discharge head 11. Further, it is possible to avoid a state in which wiping is not performed because the wiper 21 does not contact the nozzle face 11a.
In the present embodiment, a screw and a nut are used as the height adjuster 24, but it is not limited to this embodiment as long as the position of the wiper 21 in the vertical direction can be adjusted.
An example of the maintenance unit 50 is described with reference to FIGS. 11 and 12.
FIG. 11 is a schematic side view of a main portion of a liquid discharge apparatus 10 according to the present embodiment along the Y-direction (sub-scanning direction) in FIG. 1.
FIG. 12 is a schematic top view of a main part of the liquid discharge apparatus 10 of the present embodiment. In FIG. 12, an arrow Lm indicates the main-scanning direction, and an arrow Ls indicates the sub-scanning direction. The main-scanning direction Lm corresponds to the X-direction in FIG. 1. The sub-scanning direction Ls corresponds to the Y-direction in FIG. 1.
As illustrated in FIGS. 11 and 12, the maintenance unit 50 preferably includes a dummy discharge receptacle 26 that receives a liquid that does not contribute to recording on the recording medium 14. This process of discharge the liquid that does not contribute to recording on the recording medium 14 is called as "a dummy discharge process".
The dummy discharge process recovers a discharge ability of the liquid discharge head 11 by discharging the liquid onto the dummy discharge receptacle 26 to remove clogs or air in the nozzles 11n of the liquid discharge head 11.
The maintenance unit 50 includes an elastic member 27 to urge the dummy discharge receptacle 26 upward. With an urging force of the elastic member 27, the dummy discharge receptacle 26 contacts the descending carriage 12 and is pushed downward by the carriage 12 to move downward together with the cover 30. Further, as illustrated in FIG. 12, the dummy discharge receptacle 26 contacts the carriage 12 in regions 26a.
The dummy discharge receptacle 26 is mounted on the dummy discharge unit 25 and is provided with the elastic member 27 similar to the cover 30. The dummy discharge unit 25 constitutes the maintenance unit 50 together with the wiping unit 20.
When the carriage 12 descends or when the maintenance unit 50 rises, the elastic member 27 contracts. Thus, the dummy discharge receptacle 26 does not interfere with the wiping operation of the wiper 21.
The dummy discharge unit 25 preferably ascends and descends together with the wiping unit 20 for a distance identical to the moving distance of the carriage 12 that moves vertically. The dummy discharge receptacle 26 can receive the ink discharged for the dummy discharge process at an accurate distance, since the dummy discharge receptacle 26 can moves vertically for a distance as same as the distance the carriage 12. Thus, the dummy discharge receptacle 26 of the present embodiment can reduce an occurrence of ink mist.
The dummy discharge receptacle 26 may be made of material such as a stainless steel (SUS) mesh, but the material is not limited to SUS and any types of material may be used. Although a coil spring is illustrated as an example of the elastic member 27 in FIG. 11, the elastic member 27 is not limited to the coil spring as long as the elastic member 27 is capable of biasing the dummy discharge receptacle 26 upward.
In order to illustrate positions of the liquid discharge heads 11A, 11B, and 11C in FIG. 12, the carriage 12 is illustrated to see-through from above.
As illustrated in FIG. 12, a plurality (three in an example in FIG. 12) of liquid discharge heads 11A, 11B, and 11C are disposed on the carriage 12 in the sub-scanning direction Ls at regular intervals. Thereby, the present embodiment can enlarge a printing width in the sub-scanning direction Ls by one scanning movement of the carriage 12. Many liquid discharge apparatuses 10 handling a large-sized recording medium include the plurality of liquid discharge heads 11 disposed in the sub-scanning direction as in FIG. 12.
In the present embodiment, three wipers 21 (21a, 21b, and 21c) are arranged side by side to correspond to the three liquid discharge heads 11A, 11B, and 11C. Further, the cover 30 has a shape covering each wiper 21 in the retracted position.
After the carriage 12 moves above the maintenance unit 50 (wipers 21) and each wipers 21 moves to the wiping position (the position not covered by the cover 30), the carriage 12 descends. The cover 30 contacts the contact portion 12a provided on a bottom surface of the descending carriage 12.
In a conventional configuration of the maintenance unit 50, the cover 30 cannot move in the vertical direction. Thus, the carriage 12 cannot move downward. Accordingly, the wiper 21 cannot wipe the nozzle face 11a of the liquid discharge head 11. On the other hand, the present embodiment can move the cover 30 in the vertical direction. Thus, the carriage 12 can move downward. This downward movement of the carriage 12 makes the wiper 21 possible to wipe the nozzle face 11a of the liquid discharge head 11.
A configuration including the plurality of liquid discharge heads 11 as in the present embodiment enlarges size of the carriage 12. In particular, the size of the carriage 12 in the sub-scanning direction Ls is enlarged.
In a conventional configuration in which a cover 30 cannot move in the vertical direction, in order to avoid contact between the carriage 12 and the cover 30, the retracted position of the wiper 21 and the arranged position of the cover 30 has to be shifted in a sub-scanning direction Ls (the wiper 21 and the carriage 12 are arrange at a position not overlapping with the carriage 12), which leads to an increase in size of the maintenance unit 50.
On the other hand, in the present embodiment, the cover 30 can move upward and downward. Thus, it is not necessary to change the retracted position of the wiper 21 and the arrangement position of the cover 30. The size of the maintenance unit 50 in the sub-scanning direction Ls can be made substantially equal to a size of the carriage 12 in the sub-scanning direction Ls. Therefore, the present embodiment can reduce the size of the liquid discharge apparatus 10.
A number and arrangement of the liquid discharge heads 11 illustrated in FIG. 12 is merely an example and can be appropriately changed. Further, an order of operation of the carriage 12 and the wiper 21 may be changed appropriately.
In case a descending cover 30 and the wiper 21 are allowed to come into contact with each other, it is not necessary to strictly follow the order of moving the wiper 21 to the wiping position and then lowering the cover 30.
In the present disclosure, discharged liquid is not limited to a particular liquid as long as the liquid has a viscosity or surface tension to be discharged from a head. However, preferably, the viscosity of the liquid is not greater than 30 mPa·s under ordinary temperature and ordinary pressure or by heating or cooling.
Examples of the liquid include a solution, a suspension, or an emulsion including, for example, a solvent, such as water or an organic solvent, a colorant, such as dye or pigment, a functional material, such as a polymerizable compound, a resin, or a surfactant, a biocompatible material, such as DNA, amino acid, protein, or calcium, and an edible material, such as a natural colorant.
Such a solution, a suspension, or an emulsion can be used for, e.g., inkjet ink, surface treatment solution, a liquid for forming components of electronic element or light-emitting element or a resist pattern of electronic circuit, or a material solution for three-dimensional fabrication.
Examples of an energy source for generating energy to discharge liquid include a piezoelectric actuator (a laminated piezoelectric element or a thin-film piezoelectric element), a thermal actuator that employs a thermoelectric conversion element, such as a heating resistor (element), and an electrostatic actuator including a diaphragm and opposed electrodes.
"The liquid discharge device" is an integrated unit including the head and a functional part(s) or unit(s), and is an assembly of parts relating to liquid discharge. For example, "the liquid discharge device" may be a combination of the head with at least one of a head tank, a carriage, a supply unit, a maintenance unit, and a drive unit.
Herein, the terms "integrated" or "united" mean fixing the head and the functional parts (or mechanism) to each other by fastening, screwing, binding, or engaging and holding one of the head and the functional parts movably relative to the other. The head may be detachably attached to the functional part(s) or unit(s) each other.
For example, the head and a head tank are integrated as the liquid discharge device. The head and the head tank may be connected each other via, e.g., a tube to integrally form the liquid discharge device. Here, a unit including a filter may further be added to a portion between the head tank and the head of the liquid discharge device.
The liquid discharge device may be an integrated unit in which a head is integrated with a carriage.
The liquid discharge device may be the head movably held by a guide that forms part of a drive unit, so that the head and the drive unit are integrated as a single unit. The liquid discharge device may include the head, the carriage, and the drive unit that are integrated as a single unit.
In another example, the cap that forms part of the maintenance unit is secured to the carriage mounting the head so that the head, the carriage, and the maintenance unit are integrated as a single unit to form the liquid discharge device.
Further, the liquid discharge device may include tubes connected to the head mounted on the head tank or the channel member so that the head and the supply unit are integrated as a single unit. Liquid is supplied from a liquid reservoir source such as liquid cartridge to the head through the tube.
The drive unit may be a guide only. The supply unit may be a tube(s) only or a mount part (loading unit) only.
The term "liquid discharge apparatus" used herein also represents an apparatus including the head or the liquid discharge device to discharge liquid by driving the head. The liquid discharge apparatus may be, for example, an apparatus capable of discharging liquid onto a material to which liquid can adhere or an apparatus to discharge liquid toward gas or into liquid.
The "liquid discharge apparatus" may include devices to feed, convey, and eject the material on which liquid can adhere. The liquid discharge apparatus may further include a pretreatment apparatus to coat a treatment liquid onto the material, and a post-treatment apparatus to coat a treatment liquid onto the material, on which the liquid has been discharged.
The "liquid discharge apparatus" may be, for example, an image forming apparatus to form an image on a sheet by discharging ink, or a three-dimensional fabricating apparatus to discharge a fabrication liquid onto a powder layer in which powder material is formed in layers, so as to form a three-dimensional fabrication object.
In addition, "the liquid discharge apparatus" is not limited to such an apparatus to form and visualize meaningful images, such as letters or figures, with discharged liquid. For example, the liquid discharge apparatus may be an apparatus to form meaningless images, such as meaningless patterns, or fabricate three-dimensional images.
The above-described term "material on which liquid can be adhered" represents a material on which liquid is at least temporarily adhered, a material on which liquid is adhered and fixed, or a material into which li quid is adhered to permeate.
Examples of the "medium on which liquid can be adhered" include recording media, such as paper sheet, recording paper, recording sheet of paper, film, and cloth, electronic component, such as electronic substrate and piezoelectric element, and media, such as powder layer, organ model, and testing cell. The "medium on which liquid can be adhered" includes any medium on which liquid is adhered, unless particularly limited.
Examples of "the material on which liquid can be adhered" include any materials on which liquid can be adhered even temporarily, such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, and ceramic.
"The liquid discharge apparatus" may be an apparatus to relatively move a head and a medium on which liquid can be adhered. However, the liquid discharge apparatus is not limited to such an apparatus. For example, the liquid discharge apparatus may be a serial head apparatus that moves the head or a line head apparatus that does not move the head.
Examples of "the liquid discharge apparatus" further include a treatment liquid coating apparatus to discharge a treatment liquid onto a sheet surface to coat the sheet surface with the treatment liquid to reform the sheet surface and an injection granulation apparatus to eject a composition liquid including a raw material dispersed in a solution from a nozzle to mold particles of the raw material.
The terms "image formation", "recording", "printing", "image printing", and "fabricating" used herein may be used synonymously with each other.

Claims

A liquid discharge apparatus (10) comprising:
a liquid discharge head (11) including a nozzle face (11a) in which nozzles (11n) are formed to discharge liquid from the nozzles (11n);

a carriage (12) on which the liquid discharge head (11) is mounted, the carriage (12) configured to move in a horizontal direction and a vertical direction; and

a maintenance unit (50) configured to maintain the liquid discharge head (11),

wherein the maintenance unit (50) includes:
a wiper (21) configured to wipe the nozzle face (11a) of the liquid discharge head (11);

a conveyor (40) configured to reciprocally move the wiper (21) between a retracted position and a wiping position; and

a cover (30) configured to move in the vertical direction to cover the wiper (21) at the retracted position;

characterized in that the cover (30) is configured to contact with the carriage (12) movable in the vertical direction;

wherein the carriage (12) is configured to move downward to contact and push the cover (30) downward.
The liquid discharge apparatus according to claim 1, wherein the carriage (12) is configured to move downward after the wiper (21) moves from the retracted position to the wiping position.
The liquid discharge apparatus (10) according to claim 1, wherein the cover (30) includes an elastic member (32) configured to urge the cover (30) upward.
The liquid discharge apparatus (10) according to claim 1, wherein the liquid is photocurable ink.
The liquid discharge apparatus (10) according to claim 1, further comprising a controller (100) configured to control driving the carriage (12) and the conveyor (40),
wherein the controller (100) is configured to control:
driving the conveyor (40) to move the wiper (21) from the retracted position to the wiping position;

moving the carriage (12) downward; and

driving the conveyor (40) to move the wiper (21) to wipe the nozzle face (11a) of the liquid discharge head (11) while the cover (30) is pushed downward by the carriage (12) moved downward.
The liquid discharge apparatus (10) according to claim 5, further comprising a detector (17) configured to detect a thickness of a recording medium (14) onto which the liquid is discharged,
wherein the controller (100) is configured to adjust a moving distance of the carriage (12) according a reading from the detector (17).
The liquid discharge apparatus (10) according to claim 1, further comprising a height adjuster (24) configured to adjust a mounting position of the wiper (21) on the maintenance unit (50) in the vertical direction.
The liquid discharge apparatus (10) according to claim 1, wherein the maintenance unit (50) includes a dummy discharge receptacle (26) configured to receive liquid that does not contribute to image formation on a recording medium (14),
wherein the dummy discharge receptacle (26) is configured to move downward together with the cover (30) by the carriage (12) that moves downward to contact and push the dummy discharge receptacle (26) downward.