JP2019059093A - Maintenance mechanism of ink jet head - Google Patents

Abstract

To prevent deterioration of print quality caused by discharge failure of ink by preventing ink and a wipe liquid remaining in a clearance between a nozzle guard and a head nozzle surface from forming air bubbles on a nozzle plate side without causing complication, increase in size and manufacturing cost of an existing ink jet head.SOLUTION: An ink jet printer is provided with an ink jet head 31 having a nozzle plate 36 on which a nozzle for discharging ink droplets is arrayed, and a nozzle guard 44 which has an opening part 44a formed in a position corresponding to the nozzle to expose the nozzle to an external, and is laminated on the nozzle plate 36. The ink jet printer includes roller wipers 281, 281 which are slid on the nozzle guard 44 on a peripheral edge of the opening part 44a, and a wiper 285 which is slid on the nozzle plate 36 in the opening part 44a.SELECTED DRAWING: Figure 6

Description

  The present invention has a nozzle plate in which discharge ports for discharging ink droplets are arrayed, and an opening formed at a position corresponding to the discharge port and exposing the discharge port to the outside. The present invention relates to a maintenance mechanism of an ink jet printer provided with an ink jet head having stacked protective plates.

  Conventionally, various inkjet printers having a nozzle surface provided with a large number of nozzles for ejecting ink have been developed. In this inkjet printer, when printing, it is necessary to narrow the distance between the print medium and the nozzle face of the inkjet head as much as possible for improvement in image quality, and the print medium is warped or lifted due to the environment such as humidity or temperature. As shown in FIG. 10, for example, the print medium may come into contact with the ink jet head, and the nozzle guard 44 is attached to the nozzle plate 36 on which the head nozzle surface is formed to protect the nozzle surface. The measures to be taken are known.

  In addition, since the nozzle surface is exposed to air in a time when ink is not discharged, the capping member is brought into contact with the nozzle surface so as to surround the ink jet head to prevent the nozzle surface from drying. A mechanism for capping the nozzle surface in an airtight state is employed.

  By the way, in the inkjet head with a nozzle guard, although the nozzle guard 44 is adhered to the nozzle plate 36, there is a minute gap G1 between the nozzle guard 44 and the nozzle plate 36, so purge cleaning and wiping of the nozzle surface It has been pointed out that when the operation is performed, the liquid 9 such as ink and wipe liquid is mixed in the gap G1. When the capping is performed in a state where the liquid 9 such as the ink and the wipe liquid is mixed in the gap G1, the liquid 9 in the gap G1 is pressed by the contact by the cap 271 and pushed out with the air in the gap. It was found that bubbles 9a were generated around the surface.

  If the air bubbles 9a cover the nozzle array, a discharge failure of the first ink droplet may occur, which may cause a defect that the printing quality is deteriorated. In addition, the meniscus formed on the nozzle may be broken due to the impact when the bubble bursts, and the ejection failure may not be recovered unless the purge cleaning is performed. On the other hand, simply reducing the contact pressure of the cap member to prevent the generation of air bubbles can not maintain the airtight state, and the drying of the nozzle will be accelerated.

  On the other hand, conventionally, a method has been devised in which residual ink on the nozzle plate is sucked and discharged by a dummy nozzle provided in the nozzle plate portion (see, for example, Patent Document 1). More specifically, in the technique disclosed in Patent Document 1, a non-driveable dummy channel is provided in the channel array of the nozzle, and the ink liquid is supplied in a state where the dummy channel is under negative pressure. The nozzle plate is provided with a dummy nozzle hole communicating with the dummy channel, and the dummy nozzle hole can suction the residual liquid held by the nozzle guard. This can prevent the liquid from remaining on the nozzle plate.

Unexamined-Japanese-Patent No. 2014-124935

  However, in the technique disclosed in Patent Document 1 described above, a mechanism for adding a dummy channel which can not be driven to the existing ink jet head and for sucking and recovering a residual liquid by applying a negative pressure to the dummy nozzle included in the dummy channel is also possible. Since it is necessary to add the structure, the structure of the ink jet head becomes complicated, the weight of the ink jet head also increases, and the mechanism for driving the ink jet head is also enlarged, so the manufacturing cost increases and the device There is a problem that it causes the enlargement of the

  The present invention has been made in view of the above problems, and the ink and the wipe liquid remaining in the gap between the nozzle guard and the head nozzle surface without causing the complication, upsizing and increase in manufacturing cost of the existing ink jet head It is an object of the present invention to provide an ink jet head maintenance mechanism capable of preventing the occurrence of bubbles as a bubble on the nozzle plate side and avoiding the occurrence of ink discharge failure and the reduction in print quality.

In order to achieve the above object, the feature of the maintenance mechanism of the ink jet head according to the present invention is
A nozzle plate in which discharge ports for discharging ink droplets are arranged, and an opening formed at a position corresponding to the discharge port and exposing the discharge port to the outside, and protection stacked on the nozzle plate In an inkjet printer provided with an inkjet head having a plate,
First wiper means sliding on the protective plate at the periphery of the opening;
And second wiper means for sliding on the nozzle plate in the opening.

  According to the maintenance mechanism of the ink jet head according to the present invention, the first wiper means is slid on the protection plate at the periphery of the opening of the protection plate protecting the nozzle plate to wipe off the remaining ink and the wipe liquid. At the same time, in the opening, the second wiper means is slid on the nozzle plate to wipe the ink and the like. As a result, it is possible to prevent the generation of bubbles or the ink remaining in the gap between the nozzle guard and the head nozzle surface as air bubbles on the nozzle plate side without causing the complication, enlargement, and manufacturing cost of the existing inkjet head. It is possible to prevent the occurrence of ink discharge failure and the reduction in print quality.

FIG. 1 is an overall perspective view of an inkjet printing apparatus according to an embodiment of the present invention. It is a front view which shows typically schematic structure of the inkjet printing apparatus shown in FIG. It is a control block diagram of the ink jet printing apparatus shown in FIG. It is a block diagram showing composition of a maintenance control part of an ink jet printing device concerning an embodiment of the invention. It is a bottom view showing the ink jet head of the ink jet printing device concerning an embodiment of the invention from the bottom. It is a sectional view showing typically the composition of the maintenance mechanism concerning an embodiment. It is an explanatory view showing operation of a maintenance mechanism concerning an embodiment typically. It is an explanatory view showing operation of a maintenance mechanism concerning an embodiment typically. It is an explanatory view showing operation of a maintenance mechanism concerning an embodiment typically. It is explanatory drawing which shows the condition which a bubble generate | occur | produces in the inkjet head of the conventional inkjet printing apparatus.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same or equivalent parts or components are denoted by the same or similar reference numerals throughout the drawings. However, it should be noted that the drawings are schematic and different from real ones. Moreover, it is a matter of course that parts having different dimensional relationships and ratios among the drawings are included. Further, the embodiment shown below is an example of an apparatus etc. for embodying the technical idea of the present invention, and the technical idea of the present invention includes the material, shape, structure, and the like of each component. The arrangement etc. are not specified to the following. Various changes can be added to the technical idea of the present invention within the scope of the claims.

(Whole composition of inkjet printing device)
The entire configuration of an inkjet printing apparatus 1 according to an embodiment of the present invention will be described in detail. 1 and 2 schematically show the schematic configuration of the inkjet printing apparatus according to this embodiment, FIG. 3 and FIG. 4 show the configuration of the control unit and drive control, and FIG. 5 shows the inkjet head from below.

  As shown in FIGS. 1 to 3, the inkjet printing apparatus 1 according to the present embodiment includes a shuttle base unit 2, a flat bed unit 3, a shuttle unit 4, and a control unit 5.

  The shuttle base unit 2 supports the shuttle unit 4 and moves the shuttle unit 4 in the back and forth direction (sub scanning direction). The shuttle base unit 2 includes a gantry 11 and a sub scanning drive motor 12. The gantry 11 is a base that supports the shuttle unit 4, and the gantry 11 is formed in a rectangular frame shape. On the left and right frames of the gantry 11, sub-scanning drive guides 13A and 13B extending in the front-rear direction are respectively formed. The sub scanning drive guides 13A and 13B guide the shuttle unit 4 to move in the front-rear direction. The sub scanning drive motor 12 is a drive means for moving the shuttle unit 4 in the front-rear direction.

  The flat bed unit 3 holds a print medium 15 made of a base material such as a construction material or a decorative panel. The flat bed unit 3 is disposed inside the gantry 11 of the shuttle base unit 2. The flat bed unit 3 has a medium placement surface 3 a which is a horizontal surface on which the print medium 15 is placed. The flat bed unit 3 can adjust the height of the medium mounting surface 3 a by an elevating mechanism including a hydraulic drive mechanism and the like.

  The shuttle unit 4 prints an image on the print medium 15. Specifically, as shown in FIGS. 1 to 3, the shuttle unit 4 includes a housing 21, a main scanning drive guide 22, a main scanning drive motor 23, a head elevating guide 24, and a head elevating motor 25. And a head unit 26.

  The housing 21 accommodates the components such as the head unit 26. The housing 21 is formed in a gate shape straddling the flat bed unit 3 in the left-right direction. The housing 21 is supported by the gantry 11 of the shuttle base unit 2 and is movable along the sub scanning drive guides 13A and 13B.

  The main scanning drive guide 22 guides the head unit 26 to move in the left-right direction (main scanning direction). The main scanning drive guide 22 is formed in an elongated shape extending in the left-right direction. The main scanning drive motor 23 is a drive means for moving the head unit 26 in the left-right direction. The head elevating guide 24 guides the head unit 26 to move in the vertical direction. The head elevating guide 24 is formed in an elongated shape in the vertical direction. The head elevating guide 24 is configured to be movable in the left-right direction along the main scanning drive guide 22 together with the head unit 26. The head raising and lowering motor 25 is a drive means for raising and lowering the head unit 26.

  The head unit 26 discharges ink onto the print medium 15 to print an image while moving in the left-right direction along the main scanning drive guide 22. The head unit 26 includes four inkjet heads 31. The inkjet head 31 discharges the aqueous ink onto the print medium 15. The four inkjet heads 31 are arranged in parallel in the left-right direction. The four inkjet heads 31 eject inks of different colors (for example, cyan, black, magenta, and yellow).

  Further, capping units 27 are disposed below the head units 26 that have moved to the home position, which is the standby position of the head units 26. In the inkjet printing apparatus 1, the shuttle unit 4 is moved to the home position in the standby state before or after the start of the printing operation. The standby position of the shuttle unit 4 is a position shown by a solid line in FIG. 1 and is a rear end portion of the gantry 11 of the shuttle base unit 2. When the shuttle unit 4 is in the standby state, the head unit 26 is moved to the start position in the main scanning direction (right end in FIG. 2), that is, the standby position outside the sub scanning drive guide 13B. The capping unit 27 is disposed below the home position of the head unit 26, and is disposed so that the cap 271 is lifted toward the head unit 26 and fitted to each of the ink jet heads 31 to cap it.

  The control unit 5 is a module that controls the operation of each of the above-described units, and centrally controls the operation of the entire inkjet printing apparatus 1. Specifically, the control unit 5 includes a CPU, a RAM, a ROM, a hard disk, and the like, and sends various control signals to each unit while receiving detection signals from various sensors including the sensor 273. Control. In particular, the control unit 5 according to the present embodiment moves the cap 271 relative to the inkjet head 31 by controlling the cap drive unit 274 or controls the cleaning drive unit 282 to perform various purge operations and wipe operations. It also functions as a module that executes

(Configuration of maintenance mechanism)
Next, the configuration of each part of the maintenance mechanism will be described. FIG. 4 is a functional block diagram showing the relationship between the configuration of the cleaning unit 28 and the capping unit 27 constituting the maintenance mechanism according to the present embodiment, and the control unit 5.

(1) Capping unit 27
The capping unit 27 includes a base portion 272 in which the cap 271 and the cap driving portion 274 are accommodated. The cap 271 is provided for each of the ink jet heads 31, and the cap drive unit 274 and various mechanisms such as cleaning the inside of the cap can be used for the plurality of caps 271 if the respective operations can be shared for each of the ink jet heads 31. Only one unit may be provided. Hereinafter, for convenience of explanation, an example of a configuration in which one ink jet head 31 is provided for each ink jet head 31 will be described.

  The cap 271 is formed into a box shape opened upward, and covers the nozzle plate 36 from below from below so as to surround and seal the area of the nozzle plate 36 including all the nozzles 38 provided in one ink jet head 31. Member. The cap 271 is made of a member having appropriate rigidity and elasticity, for example, a rubber member such as a synthetic resin.

  The cap drive portion 274 is accommodated in a base portion 272 installed on the base 1a, and moves up and down for selectively switching the height position of the cap 271 in the vertical direction. As the cap drive part 274, for example, an appropriate lifting means such as mechanical, electromagnetic or fluid can be adopted. The cap drive unit 274 moves the cap 271 in the vertical direction with respect to the ink jet head unit 32 in a state of being moved above the main scan drive guide 22 by the main scan drive motor 23 and positioned above the capping unit 27. The state in which the cap 271 seals the nozzle surface of the nozzle plate 36 is switched to the state in which the sealing is released.

(2) Cleaning unit 28
FIG. 6 schematically shows the configuration of the cleaning unit 28 according to the present embodiment. As shown in FIG. 6, the cleaning unit 28 includes roller wipers 281 and 281 as first wiper means that slide on the surface of the nozzle guard 44 at the periphery of the opening 44 a of the nozzle guard 44 and the nozzle guard 44. In the opening 44a, a wiper 285 as a second wiper means is provided which slides on the surface of the nozzle plate 36. In the present embodiment, a pair of roller wipers 281 and 281 are disposed on both sides of the wiper 285 for wiping the nozzle plate 36 with the opening 44 a interposed therebetween, and the roller wipers 281 and 281 absorb liquid while rotating.

  More specifically, the roller wipers 281 and 281 are rotating bodies supported by the rotating shaft 281a supported by the holder portion 281b, and are formed of a soft material such as sponge, urethane, non-woven fabric, and liquid absorption, for example. It is done. The holder portion 281 b is mounted movably in the vertical direction with respect to the support base 284, is urged upward by an elastic member 283 such as a spring, and slides the wiper 285 against the nozzle guard 44 while rotating. By moving it, foreign matter attached to the surface of the nozzle guard 44 is removed. Further, the roller wipers 281 and 281 are rotatably slid by the elastic member 283 against the peripheral portion of the opening 44 a of the nozzle guard 44 in a state of pressing this portion. The pressure by the roller wipers 281, 281 is made with a pressure that causes the nozzle guard 44 to be curved so as to be convex toward the nozzle plate 36 side.

  On the other hand, the wiper 285 is erected on the support base 284 so as to remove foreign matter attached to the nozzle surface by sliding against the nozzle surface of the ink jet head 31. The wiper 285 is made of, for example, an elastically deformable member such as a rubber blade, and is formed in a rectangular thin plate in the present embodiment. In addition, it is preferable that the material which comprises the wiper 285 is a material which has the elasticity which is a grade which does not damage a nozzle surface, and as long as it performs a wiping process, you may have what kind of structure.

  Further, the upper end portion of the wiper 285 is set to be higher than the upper end surfaces of the roller wipers 281 and 281. Thus, when the roller wipers 281 and 281 are pressed against the peripheral portion of the opening 44 a of the nozzle guard 44 by the elastic member 283, the upper end of the wiper 285 is inserted into the opening 44 a of the nozzle guard 44. Become.

(Maintenance method)
The maintenance method can be implemented by operating the maintenance mechanism described above. The operation of the maintenance mechanism of this embodiment will be described below. 7 to 8 are explanatory diagrams showing an operation at the time of maintenance.

  An example of the maintenance operation of the inkjet head 31 in the inkjet printing apparatus 1 moves the inkjet head unit 32 to the home position, which is the standby position, prior to the standby time after the printing process (FIG. 7), and performs the purge operation by capping. After that, the inkjet head unit 32 is moved to the maintenance position, the wiping operation by the cleaning unit 28 (FIG. 9) is performed, the home position is returned, and capping by the capping unit 27 is performed.

  In the wiping operation, the cleaning drive unit 282 raises the support base 284 for supporting the roller wipers 281 and 281 and the wiper 285 with respect to the ink jet head 31 that has moved onto the cleaning unit 28.

  At this time, since the upper end portion of the wiper 285 is set to be higher than the upper end surfaces of the roller wipers 281 and 281, the roller wipers 281 and 281 are elastic members 283 to form the opening 44 a of the nozzle guard 44. The upper end portion of the wiper 285 is pushed into the opening 44 a of the nozzle guard 44 by being pressed against the peripheral portion.

  Then, in this state, the cleaning drive unit 282 moves the roller wipers 281 and 281 and the wiper 285 horizontally along the exposed surface (nozzle surface) of the nozzle plate 36 and the surface of the nozzle guard 44, It slides on the plate 36 and the nozzle guard 44. As a result, the roller wipers 281 and 281 rotate in a state where they are pressed by the nozzle guard 44 with a prescribed pressure, and thereby the ink and the cleaning liquid mixed in the gap between the nozzle guard 44 and the nozzle plate 36 And the drained liquid is removed by a wiper 285.

(Summary of this embodiment)
The gist of the present embodiment described above is the maintenance mechanism of the ink jet head of the present invention, and the features thereof are as follows.

That is, the first feature of the inkjet head according to the present invention as a maintenance mechanism is
The nozzle plate 36 has a nozzle plate 36 in which nozzles 38 as discharge ports for discharging ink droplets are arranged, and an opening 44 a formed at a position corresponding to the nozzles 38 and exposing the nozzles 38 to the outside. In an inkjet printing apparatus 1 provided with an inkjet head 31 having a nozzle guard 44 which is a laminated protective plate,
Roller wipers 281, 281 as first wiper means which slide on the nozzle guard 44 at the periphery of the opening 44a;
A wiper 285 as a second wiper means is slid on the nozzle plate 36 in the opening 44a.

  The second feature of the present invention is that in the above-mentioned invention, the wiper 285 is slid on the nozzle guard 44 in a state of pressing the peripheral portion of the opening 44 a of the nozzle guard 44.

  A third feature of the present invention is that in the above invention, the pressure by the roller wipers 281, 281 is made with a pressure that causes the nozzle guard 44 to be convex toward the nozzle plate 36 side.

  The present invention is not limited to the above embodiment as it is, and at the implementation stage, the constituent elements can be modified and embodied without departing from the scope of the invention. In addition, various inventions can be formed by appropriate combinations of a plurality of components disclosed in the above-described embodiment. For example, some components may be deleted from all the components shown in the embodiment.

(Action / effect)
According to the present embodiment, at the periphery of the opening 44 a of the nozzle guard 44, the roller wipers 281 and 281 as first wiper means sliding on the surface of the nozzle guard 44 and the opening 44 a of the nozzle guard 44 Since the wiper 285 as a second wiper means is slid on the surface of the nozzle plate 36, the nozzle guard 44 is wiped by the roller wipers 281 and 281, and the nozzle plate in the opening 44a is wiped by the wiper 285. 36 can be wiped out.

  In such a wiping operation, the wiper 285 can slide on the nozzle surface of the nozzle plate 36 in the opening 44a with the roller wipers 281 and 281 pressed against the peripheral portion of the opening 44a of the nozzle guard 44. Then, the ink and the cleaning liquid mixed in the gap between the nozzle guard 44 and the nozzle plate 36 can be discharged from the gap of the nozzle guard 44, and the discharged liquid can be removed by the wiper 285.

  In particular, since the pressure by the roller wipers 281 and 281 is made with a pressure that causes the nozzle guard 44 to curve so as to be convex toward the nozzle plate 36, the ink from the gap between the nozzle plate 36 and the nozzle guard 44 Etc. can be pushed out enough.

  As a result, it is possible to prevent the generation of air bubbles due to the pressure acting at the time of the capping operation, the ink remaining on the nozzle plate 36 can be efficiently absorbed by the wiper 285, an ink discharge failure occurs, It is possible to prevent the droplets of the remaining ink and the like from falling off, and it is possible to avoid the reduction in print quality.

DESCRIPTION OF SYMBOLS 1 ... Ink-jet printing apparatus 1a ... Base 2 ... Shuttle base unit 3 ... Flat bed unit 3a ... Medium mounting surface 4 ... Shuttle unit 5 ... Control part 9 ... Liquid 9a ... Bubbles 11 ... Mounting part 12 ... Subscanning drive motor 13A , 13B: Sub-scan drive guide 15: Print medium 21: Case 22: Main scan drive guide 23: Main scan drive motor 24: Head elevating guide 25: Head elevating motor 26: Head unit 27: Capping unit 28: Cleaning unit 31 ... ink jet head 32 ... ink jet head unit 36 ... nozzle plate 38 ... nozzle 44 ... nozzle guard 44a ... opening 271 ... cap 272 ... base section 273 ... sensor 274 ... cap drive 281, 281 ... roller wiper 281a ... time Axis 281b ... holder 282 ... cleaning driving unit 283 ... elastic member 284 ... support stand 285 ... wiper

Claims (3)

A nozzle plate in which discharge ports for discharging ink droplets are arranged, and an opening formed at a position corresponding to the discharge port and exposing the discharge port to the outside, and protection stacked on the nozzle plate In an inkjet printer provided with an inkjet head having a plate,
First wiper means sliding on the protective plate at the periphery of the opening;
And a second wiper unit that slides on the nozzle plate in the opening.   The maintenance mechanism of an ink jet head according to claim 1, wherein the first wiper means is slid on the protective plate in a state of pressing the peripheral portion of the opening of the protective plate.   The maintenance mechanism of an ink jet head according to claim 2, wherein the pressing by the first wiper means is performed with a pressure that causes the protective plate to be curved so as to be convex toward the nozzle plate.