WO2015190221A1

WO2015190221A1 - Ink jet head and ink jet printer

Info

Publication number: WO2015190221A1
Application number: PCT/JP2015/064110
Authority: WO
Inventors: 登志一鈴木; 鈴木　健太郎
Original assignee: 株式会社沖データ・インフォテック
Priority date: 2014-06-11
Filing date: 2015-05-15
Publication date: 2015-12-17
Also published as: JP2016013683A

Abstract

When a nozzle of an ink jet head and a recording medium come into contact with each other, the nozzle is damaged, thereby causing discharge failure. Consequently, in the present invention, by disposing nozzle guards (22) that cause a nozzle row (30) to be exposed on the nozzle surface of a nozzle plate (51) of a recording head (9), the contact of the nozzle row (30) and the recording medium is prevented. In addition, by inserting buffer plates (32) between the nozzle guards (22) and the nozzle plate (51), ink does not readily infiltrate between the nozzle guards (22) and the nozzle plate (51) and the amount of ink that overflows is reduced.

Description

Inkjet head and inkjet printer

The present invention relates to an inkjet head that records an image by discharging ink, and an inkjet printer equipped with the inkjet head.

2. Related Art Inkjet printers that record images by ejecting ink from an inkjet head onto a recording medium such as paper or resin film are known. Inkjet printers are required to improve performance such as high image quality, durability, and reliability. If foreign matter adheres to the nozzle surface of the inkjet head, ejection failure such as ink not being ejected may occur due to the influence. For this reason, in a general ink jet printer, the ink adhering to the nozzle surface of the ink jet head is periodically wiped with an elastic wipe blade to remove the adhering matter.

Also, the ink jet head reciprocates in the width direction of the recording medium with an interval of several millimeters with respect to the recording medium. If there is abnormal conveyance such as distortion of the recording medium, the inkjet head and the recording medium come into contact with each other. The nozzle plate of the ink jet head is provided with a fine nozzle on a resin plate. The contact between the recording medium and the ink jet head may cause a non-reproducible scratch on the nozzle. If ejection defects occur due to scratches, the ink jet head must be replaced. Therefore, the structure provided with the guard member which guards a nozzle is considered.

For example, Japanese Patent No. 3233164 is cited as a conventional technique. In this technique, convex guard members are arranged on both sides of the nozzle array on the nozzle surface of the head, so that even when a recording medium comes into contact, it is difficult to directly hit the nozzle and prevent scratches.

Japanese Patent No. 3233164

In the conventional technique, the guard member of the nozzle is obtained by fixing plate-like plates on both sides of the nozzle row. Therefore, when the nozzle surface is sealed with a cap, there is a step at the boundary between the nozzle plate and the guard member, so that there is a problem that a gap is formed between the nozzle plate and the cap, making sealing difficult. Further, when the cap is applied only to the nozzle surface, it is necessary to apply the cap to a narrow position, which requires a high-precision positioning, and there is a problem that the apparatus becomes complicated. Further, since the surface of the guard member is not wiped, there is a possibility that the recording medium or the like may be soiled when the ink attached to the surface is solidified and laminated.

In order to solve such a problem, the ink jet head of the present invention has a nozzle plate in which a plurality of nozzles for ejecting ink on a recording medium are arranged in a line, a main body for fixing the nozzle plate, and the nozzle plate to An ink jet comprising: a nozzle guard that protrudes in a direction of ejecting the ink; an nozzle guard that has an opening at a position where the nozzle arranged in the row is exposed and prevents contact with the recording medium; In the head, the nozzle plate is fixed to a surface of the main body portion facing the recording medium, the opening surrounds the nozzles arranged in a row, and the nozzles of the nozzle guard are exposed. The outer surface of the nozzle plate and the back surface of the nozzle guard on the surface of the main body that faces the recording medium A buffer plate is disposed on both sides of the nozzle, fixed between the nozzle plate and the nozzle guard, along the nozzles arranged in a row. To do.

An inkjet printer according to the present invention includes the above-described inkjet head, a conveyance unit that conveys a recording medium, and a carriage that is mounted with the inkjet head and moves in a direction that intersects the conveyance direction of the recording medium. The image is recorded by ejecting ink from the inkjet head onto the recording medium.

According to the present invention, it is possible to provide an ink jet head whose nozzle surface can be easily sealed with a cap, and an ink jet printer equipped with the ink jet head.

FIG. 1 is a schematic view of an ink jet printer. FIG. 2 is a schematic diagram illustrating the cap mechanism. FIG. 3 is a diagram illustrating the positional relationship between the nozzle surface and the cap. FIG. 4 is a block diagram of the ink jet printer. FIG. 5 is a diagram illustrating a second example of the positional relationship between the nozzle surface and the cap. FIG. 6 is a diagram illustrating a second example of the positional relationship between the nozzle plate and the cap.

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view of an ink jet printer. As shown in FIG. 1, the inkjet printer 1 of the present embodiment horizontally arranges a recording medium 50 and conveys it from the back of the paper surface of FIG. 1 to eject ink from an inkjet recording head 9. Images, characters and the like corresponding to the recording data are recorded on the surface of the recording medium 50. The recording medium 50 is paper, a resin film, or the like. The front direction from the back of this page is called the sub-scanning direction.

The inkjet printer 1 includes a plurality of recording heads 9 and a carriage 4 that reciprocally scans in a direction that intersects the conveyance direction of the recording medium 50, for example, a direction that is orthogonal to the recording medium 50, and a wipe unit 10 that wipes the nozzle surface of the recording head 9. And a capping unit 12 that caps the recording head 9. The direction of reciprocating scanning is called the main scanning direction. The ink jet printer 1 includes control means for controlling the entire apparatus including reception of recording data and control of recording operation. In addition, a transport unit that transports the recording medium 50 is provided. The transport unit transports the recording medium 50 in the sub-scanning direction on the substantially flat platen 2 that extends in the depth direction of the sheet of FIG. The transport unit includes a plurality of transport roller pairs 3 that are rotated by a motor 5 about a horizontal axis along the main scanning direction. The transport roller pair 3 includes a grid roller that is rotatably supported around a rotation axis parallel to the rotation axis, and a pinch roller that is energized by the grid roller. The grid roller is rotated by the motor 5. The recording medium 50 is conveyed while being sandwiched between the grid roller and the pinch roller. As the grid roller rotates, the recording medium 50 is conveyed in the sub-scanning direction.

The carriage 4 is provided so as to be movable along a carriage rail 17 extending in a direction orthogonal to the conveyance direction of the recording medium 50 above the conveyance unit, the wipe unit 10 and the capping unit 12. Further, a motor 6 is provided for reciprocating the carriage 4 on the carriage rail 17 so as to be capable of position control and speed control. The motor 6 drives an endless belt 7 disposed along the carriage rail 17. A carriage 4 is fixed to the endless belt 7. The endless belt 7 is wound around pulleys disposed on both ends in the moving direction of the carriage 4. A linear scale 8 is provided along the carriage rail 17, and a linear sensor 16 that detects the scale of the linear scale 8 is provided in the carriage 4. The position of the carriage 4 can be detected, and the positions of the plurality of recording heads 9 fixed to the fixed position of the carriage 4 can be detected accordingly.

Furthermore, a detachable ink cartridge 14 that supplies recording ink to the recording head 9 is provided, and the ink cartridge 14 and the recording head 9 are connected by an ink tube 15 that supplies ink.

In the present embodiment, the ink cartridge 14 is provided with a plurality of colors of ink for performing color recording, and can be supplied to the recording head 9 for each color via a plurality of ink tubes 15 as pipes. ing. The ink cartridge 14 is provided with a plurality of ink tanks corresponding to each ink, and each ink is accommodated in a corresponding ink tank.

The carriage 4 is provided with a plurality of recording heads 9 on the lower surface side in accordance with the ink color, recording range, and the like, and the ink supplied from the ink tube 15 is supplied to the recording head 9 that performs recording of the same color. .

Although details of the recording head 9 are not shown, a plurality of ink ejection holes are provided in an ink chamber for supplying ink to each nozzle and a nozzle surface facing the recording medium. The nozzles can be provided with an appropriate number and arrangement pitch according to the configuration of the ejection mechanism, the recording pixel pitch, and the like. For example, a large number of nozzles such as 256 can be arranged. For example, the recording head 9 may use a piezoelectric element as a recording element, or may be a recording head using a heater as a recording element.

The position control and speed control of the motor 6 are performed according to the control signal of the control means. During the recording operation, the motor 6 is controlled so that the recording head 9 reciprocates on the recording medium 50 at a predetermined speed. Further, the motor 6 can move the recording head 9 to a predetermined wiping position of the wipe unit 10 during the cleaning operation. The capping unit 12 cleans the inside of the nozzle hole of the recording head 9 by sucking the ink of the recording head 9 from the nozzle to the outside. Also, the ink is prevented from drying by capping when not in use. The schematic configuration of the capping unit 12 includes a cap 11, a cap driving unit, a suction pump, a waste ink bottle 13, and an air release valve. The air release valve is a valve that introduces outside air with the nozzle surface sealed with a cap 11.

Of these, at least a cap 11 is provided for each recording head 9. However, the cap drive unit, the suction pump, and the air release valve may be provided for each of the plurality of caps 11 when the operations of the recording heads 9 can be made common.

The cap drive unit moves up and down to selectively switch the position of the cap 11 in the vertical direction, and includes, for example, appropriate mechanical, electromagnetic, and fluid lifting means. Therefore, the cap drive unit moves the cap 11 up and down in the vertical direction with respect to the recording head 9 which is moved on the carriage rail 17 by the motor 6 and positioned above the capping unit 12. It is possible to switch between a state in which the nozzle surface is sealed and a state in which it is released.

The suction pump is for sucking contents such as air and ink in the sealed space of the cap and discharging them to the outside. For example, a rotary pump or the like can be adopted. A suction pump can also be used as a liquid passing means for passing ink from the ink cartridge 14 to the recording head 9. The suction pump has a suction port connected to the cap 11 and a discharge port connected to the waste ink bottle 13.

The wipe unit 10 wipes and cleans the nozzle surface of the recording head 9 by moving the wipe blade relative to the nozzle surface of the recording head 9 while the recording head 9 is moved above the wipe unit 10. To do.

FIG. 2 is a schematic diagram illustrating the cap mechanism. A nozzle guard 22 is fixed to the recording head 9 with an adhesive 23. The nozzle guard 22 is a metal plate that covers the periphery of the nozzles of the recording head 9. The peripheral edge of the nozzle guard 22 is bent, and the bent portion is shaped along the side surface of the recording head 9. The adhesive 23 is attached to the bent portion, and fixes the recording head 9 and the nozzle guard 22. The cap 11 is provided with a contact portion 21 that contacts the recording head 9 on the main body 20. The contact portion 21 is made of a flexible resin. Inside the cap 11, an ink receptacle 19 of a porous resin sheet is disposed. The ink receiver 19 receives the ink so that the ink does not scatter when the recording head 9 ejects ink into the cap 11. The main body 20 is provided with a suction hole 29 indicated by a dotted line communicating with the outside, and is connected to the waste ink bottle 13 via the tube 18. The suction pump 28 sucks ink and air from the cap. The suction pump 28 is disposed in the middle of the tube 18. The other end of the tube 18 is connected to the waste ink bottle 13, and the sucked ink or the like is stored in the waste ink bottle 13. The cap 11 abuts on the nozzle guard 22 to create a sealed space. The nozzle guard 22 is fixed to the recording head 9 with an adhesive so as to form a sealed space.

The spring 24 biases the cap 11 from the cap base 25 toward the recording head 9. A cam 26 is provided between the cap base 25 and the base 27. The cap 11 can be moved in the direction of the recording head 9 by rotating the cam 26 and moving it to a predetermined position away from the base 27. Thereby, the contact part 21 contacts the nozzle guard 22 and can be sealed. The abutting portion 21 is deformed by the movement of the cap base 25 and the bias of the spring 24 and comes into contact with the nozzle guard 22.

FIG. 3 is a diagram for explaining the positional relationship between the nozzle surface and the cap. A nozzle guard 22 having an opening 31 is disposed on the nozzle surface of the recording head 9 so as to surround the nozzle row 30 in which the nozzles are arranged in a row. The nozzle surface is the surface of the nozzle plate on which the nozzle rows are arranged. This nozzle row may be a plurality of rows. The entire circumference around the nozzle guard 22 is fixed to the main body of the recording head 9 by an adhesive 23, and the adhesive portion is sealed and fixed. An abutting position 33 indicated by a double ring-shaped one-dot chain line indicates a portion where the abutting portion 21 and the nozzle guard 22 are in contact with each other. The nozzle surface including the nozzle array 30 of the recording head 9 is sealed by the main body of the recording head 9, the adhesive 23, the nozzle guard 22, and the cap 11. Since the periphery of the nozzle guard 22 is fixed by the adhesive 23, there is a minute gap between the opening 31 and the nozzle surface. This is because there is no adhesive 23 in the vicinity of the opening 31 and the portion is not bonded. Buffer plates 32 are arranged on both sides of the nozzle row 30 along the longitudinal direction so as to fill the gap. The buffer plate 32 is disposed under the nozzle guard 22. The buffer plate 32 is disposed at a position corresponding to the contact position 33. In the example, the buffer plate 32 does not exist in the both end directions of the opening 31, but the buffer plate 32 may also be disposed in this portion. The buffer plate 32 may be composed of one sheet.

The nozzle surface of the recording head 9 is provided with a water repellent layer to prevent ink from spreading. For this reason, it is better not to attach an adhesive or the like to the nozzle surface. Therefore, there is a minute gap between the opening 31 and the nozzle surface. Since a minute space exists between the nozzle guard 22 and the nozzle surface, there is a possibility that ink may enter the portion. When the ink enters the minute space, the contact portion 21 presses the nozzle guard 22 when sealed by the cap 11, so that the ink protrudes from the opening 31 and reaches the nozzle row 30 to break the meniscus of the nozzle, The thickened ink enters the nozzles and causes ejection failure. In order to prevent this, a buffer plate 32 for filling the gap is arranged. The buffer plate 32 is preferably a thin metal plate such as stainless steel or titanium that is not easily affected by ink, or a resin film such as elastomer or polyimide.

Also, by arranging the buffer plate 32, the amount of movement when the nozzle guard 22 is pushed by the cap 11 is limited, and the amount of ink discharged is also reduced. Preferably, the nozzle guard 22 is disposed on both sides so as to sandwich the nozzle row 30 and the movement amount when pressed by the cap 11 of the nozzle guard 22 is regulated on both sides of the nozzle row. Since the distance between the front end side and the rear end side of the nozzle row 30 is longer than the other portions, the nozzle row 30 does not reach the nozzle row 30 even if the ink protrudes. Although the figure shows a case where only the periphery of one end portion is separated, both end sides can have the same configuration. In addition, several nozzles on the front end side and the rear end side of the nozzle row 30 are not used for image formation in order to adjust misalignment with other recording heads when the recording head 9 is mounted on the carriage 8. Therefore, no discharge failure occurs.

One end portion of the opening 31 in the longitudinal direction has a wide opening. When wiping the nozzle surface, the blade for wiping the nozzle surface is processed to be narrower than the width of the opening 31. This is because guidance is provided so that the portion of the nozzle row 30 can be wiped even if the position of the wipe blade is slightly shifted. There is also an effect that the arrangement direction can be easily distinguished from the appearance.

FIG. 4 is a block diagram of the ink jet printer. The control unit 40 is a control unit including a CPU that executes processing operations such as calculation, control, determination, and setting. The control means 40 operates according to a control program stored in the ROM 41. The RAM 42 is used as a recording data buffer, a work area for processing by the control means 40, and the like. The carriage movement motor drive circuit 43 operates under the control of the control means 40 and drives the motor 6 that moves the carriage 8. The linear sensor 16 is a sensor that detects the position of the carriage 8. The scale of the linear scale 8 arranged along the carriage rail 17 is detected by the linear sensor 16. The position of the carriage 8 is calculated and acquired based on the sensor output. The head drive circuit 44 is controlled by the control means 40. The recording head 9 is operated via the head driving circuit 44. When a plurality of recording heads 9 are mounted, the control unit 40 and the head driving circuit 44 can drive each recording head 9 individually. The head driving circuit 44 generates ink ejection timing or non-ejection timing for each recording head 9 based on information input from the control means 40 and drives the recording head 9. When ink ejection is performed, an ON waveform is generated. When ink ejection is not performed, an OFF waveform is generated and transferred to each recording head 9. The ejection timing is determined according to the position of the carriage 8.

The recording medium transport means 45 operates under the control of the control means 40. The recording medium conveyance unit 45 includes a motor 5 and a conveyance roller pair 3. The recording medium 50 is conveyed by operating the conveying roller pair 3. The wipe blade moving motor drive circuit 46 operates under the control of the control means 40. The wipe blade moving motor drive circuit 46 drives a motor that moves the wipe blade in order to wipe the nozzle surface with the wipe blade. The suction pump drive circuit 47 operates under the control of the control means 40. The suction pump drive circuit 47 drives the suction pump 28.

Each function of the inkjet printer 1 is controlled by the control means 40. Further, by storing information such as wiping operation conditions and capping operation conditions in the control means 40 in advance, predetermined wiping and capping operations can be performed. Examples of the wiping conditions include the moving speed of the wipe blade 18 and the number of rubbing times of the nozzle surface 30 of the recording head 9 of the wipe blade 18. Further, as an example of the capping condition, the rotational speed of the motor according to the position of the cam 26 for setting the contact force between the cap 11 and the recording head 9 to a predetermined pressure.

FIG. 5 is a diagram for explaining a second example of the positional relationship between the nozzle surface and the cap. FIG. 6 is a diagram illustrating a second example of the positional relationship between the nozzle plate and the cap. This will be described with reference to these two figures. The periphery of the nozzle guard 22 is fixed by an adhesive 23. Further, a second adhesive area is formed between the nozzle guard 22 and the recording head 9. Here, the main body of the recording head 9 and the back surface of the nozzle guard 22 are fixed using the second adhesive 50. This adhesion area is surrounded by the side wall of the nozzle plate 51 in which the nozzle row 30 is arranged, the back and side walls of the buffer plate 32, the back surface of the nozzle guard 22, and the main body of the recording head 9. Each is fixed by a second adhesive 50. In FIG. 6, the outer edge 60 of the nozzle plate 51 disposed between the nozzle guard 22 and the main body of the recording head 9 is indicated by a solid line. An abutting position 33 indicated by a double ring-shaped one-dot chain line indicates a position where the abutting portion 21 abuts. The nozzle plate 51 is slightly downsized to provide a second bonding area. Therefore, the cap moves and the contact portion 21 contacts the nozzle guard 22. At this time, it is preferable that the nozzle plate 51 is not present on the extended line in the cap moving direction, that is, the contact / separation direction. This is because the internal minute space is distorted by the pressure applied by the cap and a pressure difference is generated, thereby preventing the ink and the like from moving. In this configuration, the contact portion 21 contacts the outside of the nozzle plate 51. More preferably, it is in contact with the outside of the buffer plate 32. By doing so, it is fixed by the second adhesive 50, so that even if the nozzle guard 22 is pressed by the contact portion 21, it does not bend.

In addition, since the abutting portion 21 abuts on a portion of the buffer plate 32 that is away from the opening 31, the nozzle guard 22 is difficult to bend. Further, when the second adhesive 50 keeps the airtightness, the adhesive 23 may not be used. Since the number of processes is reduced, manufacturing becomes easier.

The present invention can be used for a printer having an inkjet head.

DESCRIPTION OF SYMBOLS 1 Inkjet printer 2 Platen 3 Carrying roller pair 4 Carriage 5 Motor 6 Motor 7 Endless belt 8 Linear scale 9 Recording head 10 Wipe unit 11 Cap 12 Capping unit 13 Waste ink bottle 14 Ink cartridge 15 Ink tube 16 Linear sensor 17 Carriage rail 21 Contact 22 Nozzle guard 23 Adhesive 24 Spring 25 Cap base 26 Cam 27 Base 28 Suction pump 29 Suction hole 30 Nozzle array 32 Plate 50 Recording medium

Claims

A nozzle plate in which a plurality of nozzles that discharge ink to a recording medium are arranged in a row; a main body portion that fixes the nozzle plate; and the nozzle protruding from the nozzle plate in a direction of discharging the ink, In an inkjet head having an opening at a position where the nozzles arranged in a row are exposed, and a nozzle guard for preventing contact with the recording medium,
The nozzle plate is fixed to a surface of the main body portion facing the recording medium,
The opening surrounds the periphery of the nozzles arranged in the row, and is provided at a position where the nozzle of the nozzle guard is exposed,
The outer portion of the nozzle plate on the surface of the main body facing the recording medium and the back surface of the nozzle guard are fixed with a first adhesive,
An ink jet head, characterized in that a buffer plate is disposed between the nozzle plate and the nozzle guard along the nozzles arranged in a row on both sides of the nozzle.
The nozzle guard bends from the outer periphery of the surface of the main body portion facing the recording medium along the shape of the main body portion to the opposite side to the direction in which the nozzle ejects the ink, and the bent of the nozzle guard. 2. The second adhesive is attached to the tip portion, and the entire outer periphery of the nozzle guard is fixed to the main body of the recording head by the second adhesive. The inkjet head as described.
The nozzle is sealed by a cap abutting on the nozzle guard, and the buffer plate is located at a position corresponding to the abutting position of the cap along the nozzles arranged in a row. The inkjet head according to claim 1 or 2, wherein the inkjet head is a thin plate disposed on each side.
The contact position between the cap and the nozzle guard is a position where the nozzle plate is not included on an extension line in the contact / separation direction of the cap at the corresponding contact position. 2. An ink jet head according to item 1.
3. The ink jet head according to claim 1, wherein the buffer plate is a single thin plate having an opening through which the nozzle is exposed.
A part of the outer edge of the buffer plate is fixed to the outer portion of the nozzle plate on the surface of the main body portion facing the recording medium and the back surface of the nozzle guard with the first adhesive. The inkjet head according to any one of claims 1 to 5, wherein:
An ink jet head according to claim 1;
Conveying means for conveying the recording medium;
A carriage that mounts the inkjet head and moves in a direction intersecting the conveyance direction of the recording medium;
An inkjet printer that records an image by ejecting ink from the inkjet head onto the recording medium.