JP7002267B2 - Inkjet head maintenance mechanism - Google Patents

Description

The present invention has a nozzle plate in which ejection ports for ejecting ink droplets are arranged, and an opening formed at a position corresponding to the ejection port to expose the ejection port to the outside, and the nozzle plate has an opening. The present invention relates to a maintenance mechanism of an inkjet printer provided with an inkjet head having a laminated protective plate.

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 make the distance between the print medium and the inkjet head nozzle surface as narrow as possible in order to improve the image quality, and the print medium bends or floats depending on the environment such as humidity and temperature. The print medium may come into contact with the inkjet head, for example, as shown in FIG. 10, a nozzle guard 44 is attached to the nozzle plate 36 on which the head nozzle surface is formed to protect the nozzle surface. Measures to be taken are known.

In addition, since the nozzle surface is exposed to the air while it is not ejected, the capping member that comes into contact with the nozzle surface so as to surround the inkjet head is used to prevent the nozzle surface from drying out. A capping mechanism that seals the nozzle surface in an airtight state is adopted.

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

If the bubbles 9a cover the nozzle row, the first ink droplet ejection failure occurs, which causes a problem that the print quality is deteriorated. In addition, the meniscus formed on the nozzle may be destroyed by the impact when the bubbles burst, and the ejection failure may not be recovered unless purge cleaning is performed. On the other hand, if the contact pressure of the cap member is simply lowered to prevent the generation of air bubbles, the airtight state cannot be maintained and the nozzles dry faster.

On the other hand, conventionally, a method of sucking and discharging the residual ink on the nozzle plate with a dummy nozzle provided in the nozzle plate portion has been devised (see, for example, Patent Document 1). More specifically, in the technique disclosed in Patent Document 1, a dummy channel that cannot be driven is provided in the channel row of the nozzle, and the ink liquid is supplied in a state where the dummy channel has a negative pressure. The nozzle plate is provided with a dummy nozzle hole communicating with the dummy channel, and the dummy nozzle hole can suck the residual liquid held in the nozzle guard. This can prevent the liquid from remaining on the nozzle plate.

Japanese Unexamined Patent Publication No. 2014-124935

However, in the technique disclosed in Patent Document 1 described above, a mechanism for adding an undriveable dummy channel to the existing inkjet head and sucking and recovering the residual liquid by using a dummy nozzle included in the dummy channel as a negative pressure is also available. Since it is necessary to add the inkjet head, the structure of the inkjet head becomes complicated, the weight of the inkjet head becomes large, and the mechanism for driving the inkjet head becomes large, which increases the manufacturing cost and the device. There is a problem that it causes an increase in size.

The present invention has been made in view of the above problems, and the ink and wipe liquid remaining in the gap between the nozzle guard and the head nozzle surface without causing the existing inkjet head to become complicated, large in size, and increase in manufacturing cost. It is an object of the present invention to provide a maintenance mechanism for an inkjet head that can prevent ink jet heads from being generated as bubbles on the nozzle plate side and prevent ink ejection defects from occurring and printing quality from being reduced.

In order to achieve the above object, the feature of the maintenance mechanism of the inkjet head according to the present invention is a nozzle plate in which ejection ports for ejecting ink droplets are arranged and a nozzle plate at a position corresponding to the ejection port, and the ejection port is formed. In an inkjet printer provided with an inkjet head having an opening for exposing an outlet to the outside and having a protective plate laminated on the nozzle plate, a first sliding on the protective plate at the peripheral edge of the opening. The wiper means is provided with a second wiper means slid to the nozzle plate in the opening, and the first wiper means presses the peripheral edge portion of the opening of the protective plate. The pressing by the first wiper means, which is slid on the protective plate, is characterized by a pressure such that the protective plate is curved so as to be convex toward the nozzle plate.

According to the maintenance mechanism of the inkjet head according to the present invention, the first wiper means is slid on the protective plate at the peripheral edge of the opening of the protective plate that protects the nozzle plate to wipe off the residual ink and wipe liquid. At the same time, in the opening, the second wiper means is slid on the nozzle plate to wipe off the ink and the like. As a result, it is possible to prevent ink and wipe liquid remaining in the gap between the nozzle guard and the head nozzle surface from being generated as bubbles on the nozzle plate side without complicating, increasing the size and increasing the manufacturing cost of the existing inkjet head. , It is possible to avoid deterioration of print quality due to poor ink ejection.

It is an overall perspective view of the inkjet printing apparatus which concerns on embodiment of this invention. It is a front view schematically showing the schematic structure of the inkjet printing apparatus shown in FIG. 1. It is a control block diagram of the inkjet printing apparatus shown in FIG. 1. It is a block diagram which shows the structure of the maintenance control part of the inkjet printing apparatus which concerns on embodiment of this invention. It is a bottom view which shows the inkjet head of the inkjet printing apparatus which concerns on embodiment of this invention from the bottom. It is sectional drawing which shows typically the structure of the maintenance mechanism which concerns on embodiment. It is explanatory drawing which shows typically the operation of the maintenance mechanism which concerns on embodiment. It is explanatory drawing which shows typically the operation of the maintenance mechanism which concerns on embodiment. It is explanatory drawing which shows typically the operation of the maintenance mechanism which concerns on embodiment. It is explanatory drawing which shows the situation which the bubble is generated 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 and components are designated by the same or equivalent reference numerals throughout the drawings. However, it should be noted that the drawings are schematic and may differ from the actual ones. In addition, it goes without saying that parts having different dimensional relationships and ratios are included between the drawings. Further, the embodiments shown below exemplify an apparatus or the like for embodying the technical idea of the present invention, and the technical idea of the present invention describes the material, shape, structure, and the like of each component. The arrangement etc. is not specified to the following. The technical idea of the present invention can be modified in various ways within the scope of claims.

(Overall configuration of inkjet printing equipment)
The overall configuration of the inkjet printing apparatus 1 according to the embodiment of the present invention will be described in detail. 1 and 2 schematically show a schematic configuration of an inkjet printing apparatus according to the present embodiment, FIGS. 3 and 4 show a configuration and drive control of a control unit, and FIG. 5 shows an 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 flatbed 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 front-rear direction (secondary scanning direction). The shuttle base unit 2 includes a gantry portion 11 and a sub-scanning drive motor 12. The gantry portion 11 is a base that supports the shuttle unit 4, and the gantry portion 11 is formed in a rectangular frame shape. Sub-scanning drive guides 13A and 13B extending in the front-rear direction are formed on the left and right frames of the gantry portion 11, respectively. 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 driving means for moving the shuttle unit 4 in the front-rear direction.

The flatbed unit 3 holds a print medium 15 made of a base material such as a building material or a decorative panel. The flatbed unit 3 is arranged inside the gantry portion 11 of the shuttle base unit 2. The flatbed unit 3 has a medium mounting surface 3a which is a horizontal plane on which the printing medium 15 is mounted. The flatbed unit 3 can adjust the height of the medium mounting surface 3a by an elevating mechanism including a hydraulic drive mechanism or 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. A head unit 26 is provided.

The housing 21 houses various parts such as the head unit 26. The housing 21 is formed in a gate shape straddling the flatbed unit 3 in the left-right direction. The housing 21 is supported by the gantry portion 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 a long shape extending in the left-right direction. The main scanning drive motor 23 is a driving 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 elevating motor 25 is a driving means for elevating and lowering the head unit 26.

The head unit 26 ejects ink to the printing medium 15 and prints 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 ejects water-based ink to the print medium 15. The four inkjet heads 31 are arranged side by side in the left-right direction. The four inkjet heads 31 eject inks of different colors (for example, cyan, black, magenta, and yellow).

Further, the capping unit 27 is arranged below the head unit 26 that has moved to the home position, which is the standby position of the head unit 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 portion 11 of the shuttle base unit 2. In the standby state of the shuttle unit 4, the head unit 26 is moved to the starting position (right end in FIG. 2) in the main scanning direction, that is, the standby position outside the sub-scanning drive guide 13B. The capping unit 27 is arranged below the home position of the head unit 26, and the cap 271 is raised toward the head unit 26 so as to be fitted to each of the inkjet heads 31 for capping.

The control unit 5 is a module that controls the operation of each of the above units, and comprehensively controls the operation of the entire inkjet printing apparatus 1. Specifically, this control unit 5 is configured to include a CPU, RAM, ROM, hard disk, etc., and operates by transmitting 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 controls the cap drive unit 274 to move the cap 271 relative to the inkjet head 31, or controls the cleaning drive unit 282 to perform various purge operations and wipe operations. It also functions as a module to execute.

(Structure 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 cap 271 and a base portion 272 in which the cap drive portion 274 is housed. The cap 271 is provided for each inkjet head 31, and various mechanisms such as the cap drive unit 274 and cleaning the inside of the cap can be applied to a plurality of caps 271 if each operation can be standardized for each inkjet head 31. A configuration may be provided in which only one unit is provided. In the following, for convenience of explanation, an example of a configuration in which one inkjet head 31 is provided for each of the inkjet heads 31 will be described.

The cap 271 has a box shape that opens upward, and by covering the nozzle plate 36 from below, the area of the nozzle plate 36 including all the nozzles 38 provided in one inkjet head 31 is surrounded and sealed from below. It is a member to be used. The cap 271 is made of a member having appropriate rigidity and elasticity, such as a rubber member such as a synthetic resin.

The cap drive unit 274 is housed in the base unit 272 installed on the base 1a, and moves up and down to selectively switch the height position of the cap 271 in the vertical direction. As the cap drive unit 274, for example, mechanical, electromagnetic, and fluid appropriate elevating means can be adopted. Then, the cap drive unit 274 moves the cap 271 in the vertical direction with respect to the inkjet head unit 32 which is moved on the main scan drive guide 22 by the main scan drive motor 23 and is positioned above the capping unit 27. The cap 271 switches between a state in which the nozzle surface of the nozzle plate 36 is sealed and a 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 281,281 as a first wiper means slid to the surface of the nozzle guard 44 at the periphery of the opening 44a of the nozzle guard 44, and the nozzle guard 44. In the opening 44a, a wiper 285 as a second wiper means slid on the surface of the nozzle plate 36 is provided. In the present embodiment, a pair of roller wipers 281,281 are arranged on both sides of the wiper 285 that wipes the nozzle plate 36 with the opening 44a interposed therebetween, and the roller wipers 281,281 absorb the liquid while rotating.

More specifically, the roller wipers 281,281 are rotating bodies pivotally supported by a rotating shaft 281a supported by the holder portion 281b, and are made of a soft and liquid-absorbing material such as sponge, urethane, or non-woven fabric. Has been done. The holder portion 281b is attached to the support base 284 so as to be movable in the vertical direction, is urged upward by an elastic member 283 such as a spring, and rotates while sliding the wiper 285 with respect to the nozzle guard 44. By moving the nozzle guard 44, foreign matter adhering to the surface of the nozzle guard 44 is removed. Further, the roller wipers 281,281 are rotatably slid to the peripheral portion of the opening 44a of the nozzle guard 44 by the elastic member 283 while pressing this portion. The pressing by the roller wipers 281,281 is performed with a pressure such that the nozzle guard 44 is curved so as to be convex toward the nozzle plate 36.

On the other hand, the wiper 285 is erected on the support base 284 so as to remove foreign matter adhering to the nozzle surface by sliding with respect to the nozzle surface of the inkjet head 31. The wiper 285 is made of an elastically deformable member such as a rubber blade, and is formed in the shape of a rectangular thin plate in the present embodiment. The material constituting the wiper 285 is preferably a material having elasticity enough not to damage the nozzle surface, and may have any structure as long as it is to be wiped.

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

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

As an example of the maintenance operation of the inkjet head 31 in the inkjet printing apparatus 1, the inkjet head unit 32 is moved to the home position, which is the standby position, prior to the standby time after the printing process (FIG. 7), and the purging operation is performed by capping. (FIG. 8), after that, the inkjet head unit 32 is moved to the maintenance position, a wiping operation (FIG. 9) is performed by the cleaning unit 28, the ink jet head unit 32 is returned to the home position, and capping is performed by the capping unit 27.

In the wipe operation, the cleaning drive unit 282 raises the support base 284 that supports the roller wipers 281,281 and the wiper 285 with respect to the inkjet 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 surface of the roller wiper 281,281, the roller wiper 281,281 is set by the elastic member 283 to open the nozzle guard 44 opening 44a. Pressed by the peripheral edge portion, the upper end portion of the wiper 285 is inserted into the opening 44a of the nozzle guard 44.

Then, in this state, the cleaning drive unit 282 moves the roller wipers 281,281 and the wiper 285 horizontally along the exposed surface (nozzle surface) of the nozzle plate 36 and the surface of the nozzle guard 44, thereby causing the nozzle. It slides against the plate 36 and the nozzle guard 44. As a result, the roller wipers 281,281 rotate while being pressed by the nozzle guard 44 with a specified pressure, so that the ink and cleaning liquid mixed in the gap between the nozzle guard 44 and the nozzle plate 36 are removed from the gap between the nozzle guard 44. The discharged liquid is removed with a wiper 285.

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

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

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

The third feature of the present invention is that, in the above invention, the pressing by the roller wipers 281,281 is performed with a pressure such that the nozzle guard 44 is curved so as to be convex toward the nozzle plate 36.

It should be noted that the present invention is not limited to the above embodiment as it is, and at the implementation stage, the components can be modified and embodied within a range that does not deviate from the gist thereof. In addition, various inventions can be formed by an appropriate combination of the plurality of components disclosed in the above-described embodiment. For example, some components may be removed from all the components shown in the embodiments.

(Action / effect)
According to the present embodiment, at the peripheral edge of the opening 44a of the nozzle guard 44, in the roller wipers 281,281 as the first wiper means slid to the surface of the nozzle guard 44, and in the opening 44a of the nozzle guard 44. Since the wiper 285 as a second wiper means slid on the surface of the nozzle plate 36 is provided, the nozzle guard 44 is wiped by the roller wipers 281,281, 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 be slid on the nozzle surface of the nozzle plate 36 in the opening 44a while the roller wipers 281,281 are pressed against the peripheral portion of the opening 44a of the nozzle guard 44. Therefore, the ink or 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, the pressing by the roller wipers 281,281 is performed with a pressure such that the nozzle guard 44 is curved so as to be convex toward the nozzle plate 36, so that the ink is formed from the gap between the nozzle plate 36 and the nozzle guard 44. Etc. can be sufficiently extruded.

As a result, it is possible to prevent the generation of air bubbles due to the pressure acting during the capping operation, and the ink remaining on the nozzle plate 36 can be efficiently absorbed by the wiper 285. It is possible to prevent the residual ink droplets and the like from dropping off, and it is possible to avoid a decrease in print quality.

1 ... Inkjet printing device 1a ... Base 2 ... Shuttle base unit 3 ... Flatbed unit 3a ... Medium mounting surface 4 ... Shuttle unit 5 ... Control unit 9 ... Liquid 9a ... Bubbles 11 ... Mount part 12 ... Sub-scanning drive motor 13A , 13B ... Sub-scan drive guide 15 ... Print medium 21 ... Housing 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 ... Inkjet head 32 ... Inkjet head unit 36 ... Nozzle plate 38 ... Nozzle 44 ... Nozzle guard 44a ... Opening 271 ... Cap 272 ... Base part 273 ... Sensor 274 ... Cap drive part 281,281 ... Roller wiper 281a ... Rotating shaft 281b ... Holder part 282 ... Cleaning drive part 283 ... Elastic member 284 ... Support base 285 ... Wiper

Claims (1)

It has a nozzle plate in which ejection ports for ejecting ink droplets are arranged, and an opening formed at a position corresponding to the ejection port to expose the ejection port to the outside, and is laminated on the nozzle plate for protection. In an inkjet printer with an inkjet head with a plate
A first wiper means slid on the protective plate at the periphery of the opening,
A second wiper means, which is slid on the nozzle plate in the opening, is provided .
The first wiper means is slid on the protective plate while pressing the peripheral edge portion of the opening of the protective plate.
The pressing by the first wiper means is performed with a pressure such that the protective plate is curved so as to be convex toward the nozzle plate.
Inkjet head maintenance mechanism featuring.

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