JP2007022008A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording device which prevents ejection failure called wet non-ejection caused by the ink droplets remaining after wiping when a recording head has a long size or the water repellency on ink ejection port forming surface deteriorates after a long of use. <P>SOLUTION: The surrounding of the ink ejection port forming surface 22Ks of the recording head 22K except an ink ejection port 305 is covered with an ink transfer member 404 having a capillary force and an ink holding member 405 to absorb the surplus ink droplets left on the ink ejection port forming surface 22Ks, and further to suck and retain the ink, thereby diffusing and removing the stuck ink droplets to prevent non-ejection or the like. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a capping mechanism that removes ink from an ink discharge port formation surface by capillary action, a recovery unit in which the capping mechanism is incorporated, and an image forming apparatus including the recovery unit.

  2. Description of the Related Art Inkjet image forming apparatuses that form images by ejecting ink onto recording media such as recording paper are widely used. This image forming apparatus includes a print head (recording head) in which a plurality of nozzles for discharging ink and a plurality of ink discharge ports (nozzle outlets) are formed. It is formed on the exit forming surface (face surface). This print head includes a type that ejects ink while moving in the main scanning direction together with the carriage, and a type that ejects ink while being fixed and stopped.

  In the above-described image forming apparatus, thickened ink and dust accumulate around the nozzles and ink discharge ports of the print head during image formation (recording) and standby, causing problems such as ejection failure and recording disturbance. Sometimes. In order to solve such a problem, an ink jet printer is disclosed that can clean the inside of the print head by opening the cap a plurality of times after the ink is sucked from the nozzle when the print head is cleaned. (See Patent Document 1). However, when the above recovery operation is performed, not only air bubbles but also the ink in the nozzles may be discharged and a large amount of ink may adhere to the face surface. There is. In addition, paper dust generated from the recording medium and dust / dust present in the image forming apparatus are likely to adhere to the face surface, resulting in misalignment of the ink ejection direction and non-ejection (no ink ejection). Degradation is incurred.

  As a technique for solving the above problems, a technique is disclosed in which after sucking ink in a nozzle, the face surface is wiped with a wiper blade made of an elastic body (see Patent Document 2). This technique is effective (effective) when the amount of ink adhering to the face surface is relatively small. However, if the print head is long (long head) or the water repellency of the face surface deteriorates due to long-term use, more ink droplets remain on the face surface after cleaning. I can't finish it. In particular, in a long head, a mechanism for discharging ink by pressure recovery is often used to discharge bubbles in the liquid chamber of the print head, and a large amount of ink remains on the face surface.

  In addition, there is known a print head in which variation in ink flying and ink scattering are prevented by subjecting the face surface of the print head to water repellent treatment by a specific method (see Patent Document 3). However, when pigment ink is used, the wettability between the face surface and the pigment ink is improved due to the influence of the pigment and the dispersant. For this reason, immediately after the pressure recovery is performed, the ink spreads over the entire face surface and this ink is transferred to the cap. Therefore, a gap is formed between the face surface and the cap, and the ink leaks, causing ink leakage. There is a risk that a problem will occur.

In addition, an ink removal member having a plurality of plate-like portions is provided in the recovery processing system so as to face the ink discharge port, and the ink discharged by the pressure circulation is discharged from the ink discharge port by these ink removal members. An inkjet image forming apparatus that removes the image is also known (see Patent Document 4). However, when the distance between the ink removing member having a plurality of plate-like portions and the face surface is constant, the capillary action generated by this ink removing member is the same in the vicinity of the nozzle and other parts, and the wettability with the face surface However, in the case of ink having a poor wettability, the effect of removing ink is great. However, in the case of ink having good wettability with the face surface, the effect may not be sufficiently exhibited.
JP 05-000517 A Japanese Patent Laid-Open No. 10-250087 Japanese Patent Laid-Open No. 10-286967 Japanese Patent Laid-Open No. 11-309871

  SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a capping mechanism, a recovery unit, and an image forming apparatus that can remove ink from the face surface regardless of the wettability between the ink discharge port forming surface (face surface) and the ink. And

  In order to achieve the above object, according to the present invention, in a recording head having an ink discharge port forming surface on which a plurality of ink discharge ports of an ink jet recording apparatus are formed, ink droplets adhering to the ink discharge port forming surface are predetermined. An ink jet recording apparatus comprising an ink transport surface that leads in the direction of.

  An ink jet recording apparatus comprising: an ink holding member that holds ink guided in a predetermined direction on the ink transport surface.

  The ink-jet recording apparatus is characterized in that a plurality of concave and convex grooves are formed on the ink transport surface.

  The ink jet recording apparatus is characterized in that a groove is formed on the ink transport surface in a direction to guide ink droplets on the ink discharge port forming surface to the ink holding member.

  The ink jet recording apparatus is characterized in that a plurality of ink discharge ports of the recording head protrude from a plurality of concave and convex portions formed on the ink transport surface.

  According to the present invention, in an ink jet recording apparatus including a recording head having an ink discharge port forming surface on which a plurality of ink discharge ports for discharging ink in recording or the like are formed, the recording head includes an ink transport surface provided with a groove. Thus, when the recovery operation is performed, the ink droplets that are about to spread on the ink discharge port formation surface are pulled by the capillary force of the groove and sucked up to remove the ink droplets remaining on the ink discharge port formation surface. It becomes possible to do. Therefore, stable image quality performance can be obtained, the reliability of the recording head can be maintained, and a high-quality ink jet recording apparatus can be provided.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  An example of an image forming apparatus incorporating a recovery unit having a capping mechanism according to the present invention will be described with reference to FIG.

  FIG. 1 is a front view schematically showing an example of an ink jet image forming apparatus of the present invention.

  The image forming apparatus 10 is connected to a host PC (personal computer) 12 that sends image information to the image forming apparatus 10. In the image forming apparatus 10, four (four) print heads 22 </ b> K, 22 </ b> C, 22 </ b> M, and 22 </ b> Y are arranged side by side in the conveyance direction (arrow A direction) of the recording medium (roll paper here). . The four print heads 22K, 22C, 22M, and 22Y respectively eject black, cyan, magenta, and yellow inks. These four print heads 22K, 22C, 22M, and 22Y are so-called line heads, and extend in a direction orthogonal to the paper surface of FIG. 1 (a direction orthogonal to the arrow A direction). The lengths of these four print heads 22K, 22C, 22M, and 22Y are slightly longer than the maximum width (the length in the direction perpendicular to the paper surface of FIG. 1) of the recording medium that can be printed by the image forming apparatus 10. These four print heads 22K, 22C, 22M, and 22Y are fixed and do not move during image formation, but move in the vertical direction (arrow B direction) during a recovery operation described later.

  A recovery unit 40 is incorporated in the image forming apparatus 10 so that ink can be stably ejected from the four print heads 22K, 22C, 22M, and 22Y. The recovery unit 40 includes a capping mechanism 50 that removes ink from the ink discharge port formation surfaces 22Ks, 22Cs, 22Ms, and 22Ys of the four print heads 22K, 22C, 22M, and 22Y during the recovery operation.

  The capping mechanism 50 is provided independently for each of the print heads 22K, 22C, 22M, and 22Y. In the example of FIG. 1, six colors (that is, six capping mechanisms 50) are shown. Minute is a preliminary mechanism when the print head is added. The capping mechanism 50 includes a wiper blade, an ink removing member, a wiper blade holding member, a cap, and the like, which will be described later, and details thereof will be described later.

  The roll paper P is supplied from the roll supply unit 24 and continuously conveyed in the arrow A direction by the conveyance mechanism 26 incorporated in the image forming apparatus 10. The transport mechanism 26 includes a transport belt 26a for loading and transporting the roll paper P, a transport motor 26b for rotating the transport belt 26a, and a roller 26c for applying tension to the transport belt 26a.

  When forming an image on the roll paper P, after the recording start position of the roll paper P being conveyed reaches below the black print head 22K, the black ink is transferred from the print head 22K based on the recording data. Is selectively discharged. Similarly, ink of each color is ejected in the order of the print head 22C, the print head 22M, and the print head 22Y to form a color image on the roll paper P. In addition to the components and members described above, the image forming apparatus 10 includes ink cartridges 28K, 28C, 28M, 28Y that store ink supplied to the print heads 22K, 22C, 22M, 22Y, print heads 22K, 22C, It comprises a pump unit (see FIG. 3) for supplying ink to 22M and 22Y and performing a recovery operation.

  The electrical system of the image forming apparatus 10 will be described with reference to FIG.

  FIG. 2 is a block diagram showing an electrical system of the image forming apparatus of FIG.

  Recording data and commands transmitted from the host PC 12 are received by the CPU 100 via the interface controller 102. The CPU 100 is an arithmetic processing unit that performs overall control such as reception of recording data of the image forming apparatus 10, recording operation, handling of the roll paper P, and the like. After analyzing the received command, the CPU 100 renders the image data of each color component of the recording data by developing a bitmap on the image memory 106. As an operation process before recording, the capping motor 122 and the head up / down motor 118 are driven via the output port 114 and the motor driving unit 116, and the print heads 22K, 22C, 22M, and 22Y are separated from the capping mechanism 50 for recording. Move to position (image forming position).

  Subsequently, the roll motor (not shown) that feeds the roll paper P through the output port 114, the motor drive unit 116, the transport motor 120 that transports the roll paper P at a low speed, and the like are driven to drive the roll. Paper P is conveyed to the recording position. The leading end position of the roll paper P is detected by a leading edge detection sensor (not shown) for determining the timing (recording timing) at which ink starts to be discharged onto the roll paper P conveyed at a constant speed. Thereafter, in synchronism with the conveyance of the roll paper P, the CPU 100 sequentially reads the recording data of the corresponding color from the image memory 106, and prints the read data to the print heads 22K, 22C, 22M, 22Y. Transfer via the circuit 112.

  The operation of the CPU 100 is executed based on a processing program stored in the program ROM 104. The program ROM 104 stores a processing program and a table corresponding to a control flow described later. A work RAM 108 is used as a working memory. During the cleaning and recovery operations of the print heads 22K, 22C, 22M, and 22Y, the CPU 100 drives the pump motor 124 via the output port 114 and the motor driving unit 116, and controls ink pressurization and suction.

  The recovery unit incorporated in the image forming apparatus 10 will be described with reference to FIGS.

  FIG. 3 is a schematic diagram illustrating a recovery unit of the image forming apparatus. FIG. 4 is a schematic diagram showing the positional relationship between the print head and the capping mechanism during printing. FIG. 5 is a schematic diagram showing the positional relationship between the print head and the capping mechanism during the recovery operation. Although FIG. 3 shows a recovery unit that supplies ink to the print head 22K and recovers the print head 22K, the other print heads 22C, 22M, and 22Y are recovered in the same procedure by the recovery unit having the same structure. In FIG. 3, the arrow indicating the ink movement indicates the ink flow when the recovery operation of the print head is being executed.

  During printing, as shown in FIG. 4, the print heads 22K, 22C, 22M, and 22Y are fixed at predetermined positions above the roll paper P, and the six capping mechanisms 50 do not hinder ink ejection. In this way, the print heads 22K, 22C, 22M, and 22Y are positioned on the sides. On the other hand, when the recovery operations of the print heads 22K, 22C, 22M, and 22Y are performed, the print heads 22K, 22C, 22M, and 22Y move upward, and the four capping mechanisms 50 out of the six capping mechanisms 50 are moved. As shown in FIG. 5, the print heads 22K, 22C, 22M, and 22Y are positioned directly below the ink discharge port forming surfaces 22Ks, 22Cs, 22Ms, and 22Ys.

  When the ink discharge state from the print head 22K is restored to the initial discharge state, first, the pump motor 124 (see FIG. 2) is activated under the control of the CPU 100, and the pressure pump 202 starts operating. Prior to the start of this operation (in advance), the recovery valve 204b is closed and the recycle valve 204c is open. Note that the CPU 100 controls the suction pump 204 to be activated almost simultaneously with the pressurizing pump 202.

  When the pressurizing pump 202 is operated, the ink in the sub-tank 206 is directed to the common liquid chamber 22Ka of the print head 22K via the pressurizing pump 202, but the recovery valve 204b on the outlet side is closed. All of the ink thus applied is pushed out from the nozzle 22Kb of the print head 22K to the capping mechanism 50. As a result, the nozzles 22Kb of the print head 22K are restored to a healthy state (initial ink ejection state).

  The ink pushed out to the ink reservoir 406 (see FIG. 7) in the capping mechanism 50 is sucked through the filter 208, the recycle valve 204c, and the suction pump 204 in this order when the suction pump 204 is driven, and returns to the sub tank 206. So it will be recycled. Further, the sub tank 206 is provided with an atmosphere release valve 204d for communicating the inside with the atmosphere. Further, a supply valve 212 and a filter 214 are attached to the ink supply pipe 210 between the suction pump 204 and the ink cartridge 28K.

  In addition to the above-described recovery operation, various kinds of purposes are aimed at removing bubbles grown in the common liquid chamber 22Ka by circulating ink between the sub tank 206 and the print head 22K with the recovery valve 204b open. The details are omitted.

  In a print head having a large number of nozzles such as a line head, the above-described recovery operation is executed a plurality of times by dividing a large number of nozzles into a small number of nozzles and leaving only the small number of nozzles in a split open state. As a result, the recovery performance is high for all nozzles, which makes sense.

However, such a division method has problems such as a complicated recovery mechanism and a long recovery time. Therefore, in many cases, the recovery operation of all the nozzles is performed in one recovery.

  With reference to FIG. 6, the procedure of the recovery operation for recovering the print head will be described.

  FIG. 6 is a flowchart showing the procedure of the recovery operation of the print head.

  The flow shown in FIG. 6 is executed by the CPU 100 according to the control program stored in the program ROM 104. Since the recovery operations of the print heads 22K, 22C, 22M, and 22Y are simultaneously performed in the same procedure, the print head 22K will be described as an example here. In starting this recovery operation, first, the print head 22K is moved from the capping position to the recovery position (the position shown in FIGS. 3 and 5) (S601). At the recovery position, the face surface 22Ks of the print head 22K is set to contact the ink guide 401 (see FIG. 7). That is, when the print head 22K is located at the recovery position, the ink guide 401 is in contact with the face surface 22Ks.

  Subsequently, the recovery valve 204b (see FIG. 3) is closed (S602), and the suction pump 204 and the pressure pump 202 are driven (turned on) (S603, S604). By driving these two pumps 204 and 202, ink is pushed out from the nozzles of the print head 22K and guided to the ink reservoir 406 (see FIG. 7) below the cap 402 (see FIG. 7). At this time, since the capping mechanism 50 described later is used, the ink is efficiently removed from the face surface 22Ks by capillary action regardless of the type of ink pushed out from the nozzle (wetting with the face surface 22Ks). .

Since the ink stored in the ink reservoir 406 is returned to the sub tank 206 by the suction pump 204 during operation, the ink is recycled.

  The above-described recovery operation (operation in which the print head 22K is positioned at the recovery position, the recovery valve 204b is closed, and the suction pump 204 and the pressure pump 202 are turned on) is continued for a predetermined time (S605). After the predetermined time has elapsed, the pressurizing pump 202 is stopped (turned off) (S606). Subsequently, the print head 22K is returned to the capping position (S607), and a predetermined number of preliminary ejections are performed (S608). Then, the ink adhering to the face surface 22Ks is wiped off by wiping (wiping) the face surface 22Ks of the print head 22K with a wiper blade (not shown) (S609). Further, when a predetermined time has passed (S610), the suction pump 204 is stopped (turned off) (S611), the ink reservoir 406 in the capping mechanism 50 (see FIG. 3) is stopped, and the ink suction operation is stopped. finish.

  Next, an example of the print head in the ink jet recording apparatus according to the present invention will be described in detail using the print head 22K as an example with reference to FIG. (The same applies to the other print heads 22C, 22M, and 22Y.)

  As shown in FIG. 8, the ink droplets discharged from the ink discharge port 305 of the nozzle 22 </ b> Kb of the conventional print head 22 </ b> K fall directly below by a plurality of ink guides 401 and are stored in the cap 402. However, if the water repellency of the ink discharge port forming surface 22Ks deteriorates due to long-term use, some of the discharged ink droplets tend to spread on the ink discharge port forming surface 22Ks. Bridges between the ink discharge port forming surface 22Ks and the cap 402, and flows down to the outside of the cap 402, leading to ink leakage.

Therefore, as shown in FIG. 7, in the embodiment of the present invention, the ink transport member 404 is provided on the ink discharge port forming surface 22Ks excluding the ink discharge port 305. The ink transport member 404 has a plurality of grooves (unevenness) formed on the entire surface of the ink transport member 404. The ink transport member 404 sucks excess ink droplets remaining on the ink discharge port forming surface 22Ks and sucks the ink transport member 404. Ink droplets are absorbed and held by an ink holding member 405 that can absorb and hold ink droplets, thereby reducing residual ink droplets that cause problems such as ink leakage and image defects, and forming ink ejection openings. It is possible to always maintain a clean state on the surface.

The width of the groove is, for example, 5 μm to 150 μm, and more preferably 10 μm to 100 μm. (See Figure 9)

Furthermore, the depth of the groove is desirably in the range of 10 μm to 100 μm depending on the width of the groove.

  The reason why the ink conveying member as described above can guide the ink in a predetermined direction is a capillary phenomenon generated by the groove. Therefore, if the groove is too large, sufficient capillary force is not exhibited and ink cannot be moved quickly, and the adverse effects of ink scattering and thickened ink cannot be solved.

  On the other hand, if the groove is smaller than 5 μm, a minute amount of ink remaining on the wall of the groove adheres and closes the groove, resulting in a problem that the ink does not quickly move to a predetermined position.

  Further, the groove formation pitch is 0.01 mm to 1 mm, particularly for cleaning a long recording head uniformly over a long period of time.

The direction in which the groove is formed is a direction perpendicular to the longitudinal direction of the recording head (left and right in the figure) on the ink discharge port forming surface 22Ks, and an ink holding member 405 that holds ink droplets on the side of the recording head. It is formed in the vertical direction in the figure toward the direction. As a result, the ink droplets remaining on the ink discharge port forming surface can be moved in the direction of the ink holding member 405 more quickly.

Further, the ink discharge port 305 is provided on the ink discharge port forming surface 22Ks in order to prevent the problem that the ink discharged for image formation is pulled by the ink transport member 404 and the ink does not land at a regular position. It is configured to protrude from the concavo-convex convex portion of the ink transport member 404.

The second embodiment of the present invention will be described in detail using the print head 22K as an example with reference to FIG. (The same applies to the other print heads 22C, 22M, and 22Y)

In the second embodiment, when the print head 22K is manufactured, the plurality of grooves are directly formed on the ink discharge port forming surface 22Ks, so that the ink conveying member 404 and the print head shown in the first embodiment are integrally configured. It is an embodiment. The ink droplets sucked up by the plurality of directly processed grooves are absorbed and held by the ink holding member 405 provided on the side surface of the print head 22K.

Regarding the plurality of grooves, as in the first embodiment, the width of the groove is, for example, 5 μm to 150 μm, more preferably in the range of 10 μm to 100 μm, the depth is within 10 μm to 100 μm depending on the width of the groove, and A pitch interval between 0.01 mm and 1 mm is most effective. (See Figure 9)

The direction in which the plurality of grooves are formed is as shown in the figure, and is formed toward the ink holding member 405.

Further, the ink discharge port 305 is configured to protrude from the uneven portions of the plurality of grooves formed directly on the ink discharge port forming surface 22Ks of the print head 22K in order to land the ink at a regular position. Yes.

By adopting the configuration as described above, the same effects as in the first embodiment can be obtained.

  As mentioned above, the invention made by the present inventor has been specifically described based on the present embodiment. However, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the scope of the invention. Needless to say.

1 is a front view schematically showing an example of an ink jet recording apparatus of the present invention. FIG. 2 is a block diagram illustrating an electrical system of the image forming apparatus in FIG. 1. It is a schematic diagram showing a recovery unit of the image forming apparatus. FIG. 4 is a schematic diagram illustrating a positional relationship between a print head and a capping mechanism during printing. FIG. 4 is a schematic diagram illustrating a positional relationship between a print head and a capping mechanism during a recovery operation. It is a flowchart which shows the procedure of recovery operation | movement of a print head. It is sectional drawing showing the Example of the print head of the inkjet recording device of this invention. It is sectional drawing showing the Example of the print head of the conventional inkjet recording device. Sectional drawing which shows the example of the groove | channel of the ink conveyance member of this invention. FIG. 6 is a schematic diagram showing Example 2 of the present invention.

Explanation of symbols

10 Image forming apparatuses 22K, 22C, 22M, 22Y Print heads 22Ks, 22Cs, 22Ms, 22Ys Ink ejection port forming surface (face surface)
22 Kb Nozzle 50 Capping mechanism 305 Ink discharge port 401 Ink guide 402 Cap 404 Ink transport member 405 Ink holding member 406 Ink reservoir

Claims (5)

A recording head having an ink discharge port forming surface in which a plurality of ink discharge ports of an ink jet recording apparatus are formed, and having an ink transport surface for guiding ink droplets adhering to the ink discharge port forming surface in a predetermined direction. An ink jet recording apparatus. The ink jet recording apparatus according to claim 1, further comprising an ink holding member that holds ink guided in a predetermined direction on the ink transport surface. 2. The ink jet recording apparatus according to claim 1, wherein the ink conveying surface is formed with a plurality of grooves having unevenness. 2. The ink jet recording apparatus according to claim 1, wherein the ink transport surface is formed with a groove in a direction in which ink droplets on the ink discharge port forming surface are guided to the ink holding member. 5. The ink jet recording apparatus according to claim 1, 3, or 4, wherein the ink ejection port of the recording head protrudes from a plurality of concave and convex portions formed on the ink transport surface.

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