JP2015020407A - Ink jet image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent damage of an ink discharge surface of an ink jet head and retransferring of ink to the ink discharge surface, and form a good image.SOLUTION: An ink jet image formation device comprises an ink jet head 31 which discharges ink from an ink discharge surface where plural nozzles are formed, and a control part 8 which controls so that the ink discharge surface after discharging ink from the ink discharge surface is wiped free of ink along the ink discharge surface by using an ink wiping member at a maintenance time. The control part 8, at the maintenance time, controls so that the ink wiping member with contacting to the ink discharge surface is moved at a first speed at least from a maintenance start position until reaching the nearest nozzle, and, thereafter, the ink wiping member is moved at a second speed which is faster than the first speed.

Description

  The present invention relates to an inkjet image forming apparatus that performs maintenance on an ink ejection surface of an inkjet head, and in particular, inkjet image formation that forms a good image by preventing damage to the ink ejection surface and retransfer of ink to the ink ejection surface. Relates to the device.

  In the inkjet image forming apparatus, in order to maintain the normal ejection state of the inkjet head, for example, a purge is performed to forcibly eject ink from the ink ejection surface of the inkjet head in which a plurality of nozzles are formed, and the ejected ink At the same time, maintenance is performed to wipe off dust adhering to the ink ejection surface with a wiper blade.

  Here, for example, in Patent Document 1, in order to prevent scattering of ink adhering to the wiper blade when the wiper blade wipes off the ink discharge surface and unwiping of the ink discharge surface, the wiper blade has an ink discharge surface. Inkjet image forming apparatuses that wipe the ink discharge surface by reducing the amount of biting of the wiper blade relative to the ink discharge surface and the moving speed immediately before wiping are proposed.

JP 2011-084004 A

  By the way, in the inkjet image forming apparatus, when a predetermined time or more has passed since the previous maintenance, that is, the maintenance operation of the inkjet head, the ink adhered to the wiper blade may be dried and solidified, or dust or the like may adhere to the wiper blade. . When maintenance of the ink jet head is performed in such a state, the newly purged ink is wiped off without sufficiently reaching the wiper blade at the head wiping start portion on the ink ejection surface of the ink jet head. The ink repellent film may be peeled off, or the ink discharge surface may be damaged, or the old ink thickened on the wiper blade may be retransferred to the ink discharge surface and the quality of the formed image may be deteriorated.

  However, in the inkjet image forming apparatus described in Patent Document 1 described above, the wiper blade biting amount and moving speed are set immediately before the wiper blade wipes off the ink discharge surface for the purpose of preventing ink scattering and wiping of the ink discharge surface. It is reduced, and no consideration is given to the start of wiping the head on the ink ejection surface.

  For this reason, in the inkjet image forming apparatus described in Patent Document 1, when a predetermined time or more has elapsed since the previous maintenance operation, the ink repellent film on the ink ejection surface of the inkjet head is scratched and the ink repellent film is peeled off, or old ink is removed. There is a possibility that the quality of the image formed by retransfer is deteriorated.

  The present invention has been made in view of the above problems, and provides an inkjet image forming apparatus that prevents damage to the ink ejection surface of an inkjet head and retransfer of ink to the ink ejection surface, and forms a good image. For the purpose.

  In order to achieve the above object, a first feature of an inkjet image forming apparatus according to the present invention is that an inkjet head that ejects ink from an ink ejection surface on which a plurality of nozzles are formed, and ink from the ink ejection surface during maintenance are provided. A control unit that controls the ink ejection surface after being discharged to be wiped along the ink ejection surface by the ink wiping member, and the control unit controls the ink wiping member during the maintenance. The ink wiping member is brought into contact with the ejection surface and moved at a first speed at least until reaching the nozzle closest to the maintenance start position, and then at a second speed that is faster than the first speed. Control to move.

  In order to achieve the above object, a second feature of the inkjet image forming apparatus according to the present invention is that the control unit reaches the nozzle closest to the maintenance start position at the first speed during the maintenance. Sometimes the ink wiping member is stopped for a predetermined time, and the ink wiping member is moved at the second speed after stopping for a predetermined time.

  In order to achieve the above object, a third feature of the inkjet image forming apparatus according to the present invention is that the control unit moves the ink wiping member at the first speed during the maintenance. A non-contact ink wiping process is performed in which the tip of the ink wiping member is brought into contact with an ink droplet on the ink ejection surface, but the ink on the ink ejection surface is wiped in a non-contact state without being brought into contact with the ink ejection surface. .

  According to the first feature of the inkjet image forming apparatus according to the present invention, during the maintenance of the inkjet head, the ink wiping member is moved along the ink ejection surface until the nozzle closest to the maintenance direction is reached from the maintenance start position. The ink wiping member becomes wet with ink droplets on the ink ejection surface. Thereafter, the ink wiping member is moved at a second speed higher than the first speed to perform a speed change ink wiping process for wiping ink droplets. Further, it is possible to prevent the old ink adhering to the ink wiping member from being re-transferred to the ink discharge surface of the inkjet head, and to form a good image.

  Further, according to the second feature of the ink jet image forming apparatus according to the present invention, when the ink wiping member moves at the first speed, the ink wiping is performed when the nozzle reaches the nozzle closest to the maintenance direction from the maintenance start position. Since the member is stopped for a predetermined time, the ink wiping member can be more reliably wetted by the ink droplets on the ink ejection surface.

  According to the third feature of the ink jet image forming apparatus of the present invention, prior to moving the ink wiping member at the first speed, that is, before performing the speed change ink wiping process, the tip of the ink wiping member is moved to the ink. The non-contact ink wiping process is performed to wipe the ink on the ink ejection surface in a non-contact state while contacting the ink droplets on the ejection surface but not contacting the ink ejection surface. It is possible to further prevent retransfer of ink having an old surface.

1 is a schematic configuration diagram of an inkjet image forming apparatus according to an embodiment of the present invention. It is a top view of a maintenance unit. It is a disassembled perspective view of a maintenance unit and an inkjet head. It is sectional drawing along the AA line in FIG. It is a block diagram which shows the function structure of the inkjet image forming apparatus of embodiment which concerns on this invention. 3 is a flowchart showing a maintenance operation in the inkjet image forming apparatus according to the embodiment of the present invention. It is an operation | movement figure for demonstrating the maintenance operation | movement in the inkjet image forming apparatus of embodiment which concerns on this invention. It is an operation | movement figure for demonstrating the maintenance operation | movement in the inkjet image forming apparatus of embodiment which concerns on this invention. It is an operation | movement figure for demonstrating the maintenance operation | movement in the inkjet image forming apparatus of embodiment which concerns on this invention. It is explanatory drawing which shows the normal wipe process in the inkjet image forming apparatus of embodiment which concerns on this invention, Comprising: (a) is a front view, (b) is a bottom view. It is explanatory drawing which shows the speed change wipe process in the inkjet image forming apparatus of embodiment which concerns on this invention. It is explanatory drawing which shows the relationship between the speed and position of a wiper blade in the speed change wipe process in the inkjet image forming apparatus of embodiment which concerns on this invention. It is explanatory drawing which shows the non-contact wiping process in the inkjet image forming apparatus of embodiment which concerns on this invention. It is explanatory drawing which shows another example of the relationship between the speed of a wiper blade and the position in the speed change wipe process in the inkjet image forming apparatus of embodiment which concerns on this invention.

  Hereinafter, an inkjet image forming apparatus according to an embodiment of the present invention will be described. In addition, each embodiment shown below illustrates the apparatus etc. for actualizing the technical idea of this invention, Comprising: The technical idea of this invention is arrangement | positioning of each component etc. below. It is not something specific. The technical idea of the present invention can be variously modified within the scope of the claims.

  FIG. 1 is a schematic configuration diagram of an inkjet image forming apparatus according to an embodiment of the present invention, and FIG. 2 is a plan view of a maintenance unit provided in the inkjet image forming apparatus according to the embodiment of the present invention shown in FIG. 3 is an exploded perspective view of the maintenance unit and the inkjet head provided in the inkjet image forming apparatus according to the embodiment of the present invention. FIG. 4 is a sectional view taken along line AA in FIG. These are block diagrams which show the function structure of the inkjet image forming apparatus of embodiment which concerns on this invention. In the following description, the paper surface direction of FIG. Moreover, as shown in FIG. 1, when viewed from the user, the vertical and horizontal directions are the vertical and horizontal directions.

  As shown in FIG. 1, an inkjet image forming apparatus 1 according to an embodiment of the present invention includes a transport unit 2, a head unit 3, and a maintenance unit 4.

  The conveyance unit 2 includes a conveyance belt 21 provided to face the head unit 3, a driving roller 22 that drives the conveyance belt 21 to rotate, and driven rollers 23, 24, and 25 that are driven by the driving roller 22.

  The conveying belt 21 is stretched over the driving roller 22 and the driven rollers 23, 24, and 25, and moves endlessly by driving of the driving roller 22 during printing, and is supplied from a paper supply stand (not shown) provided on the left side. Hold and transport.

  As shown in FIGS. 7 and 8 described later, the transport unit 2 performs maintenance on a print position where a paper transport process is performed during printing by a vertical motor 44, which will be described later, and a position lower than the print position. The unit 4 is configured to be movable between a retreat position where the unit 4 is moved and a maintenance position where the maintenance unit 4 moves upward from the retreat position and causes the maintenance unit 4 to perform maintenance of the head unit 3 as shown in FIG. Has been. The transport unit 2 is moved to the retracted position in order to move the maintenance unit 4 between the transport unit 2 and the head unit 3 when the head unit 3 is maintained.

  The head unit 3 includes line-type inkjet heads 31C, 31K, 31M, and 31Y, and prints an image by ejecting ink onto a sheet conveyed by the conveyance belt 21. The inkjet heads 31C, 31K, 31M, and 31Y are arranged at predetermined intervals in the left-right direction above the transport unit 2. The ink jet heads 31C, 31K, 31M, and 31Y respectively have different types of inks of C (cyan), K (black), M (magenta), and Y (yellow), and nozzles 311b ( (See FIG. 10B.)

  As shown in FIGS. 2 and 3, the inkjet head 31C is composed of six unit heads 311C arranged in a staggered matrix of 2 columns × 3 rows. Similarly, the inkjet heads 31K, 31M, and 31Y are each composed of six unit heads 311K, 311M, and 311Y.

  In addition, when it is not necessary to distinguish between colors, the alphabetic suffixes (C, K, M, Y) indicating the colors in the code are omitted. For example, the code of the inkjet head is “31” and the code of the unit head Is expressed as “311”.

  On the ink ejection surface 311a of the unit head 311 of the inkjet head 31, for example, 318 nozzles 311b are formed in two rows as shown in FIG. 10B described later, and an ink repellent film is formed. ing. The ink repellent film is made of a material having a property of repelling ink, for example, an amorphous fluororesin. Therefore, ink ejected from the adjacent nozzle 311b is combined by the ink repellent film on the ink ejection surface 311a, thereby forming an ink droplet 9 as shown in FIG. 10B.

  The maintenance unit 4 performs maintenance on the ink ejection surface of the unit head 311. The maintenance unit 4 is arranged at a storage position indicated by a solid line in FIG. 1 during printing. The storage position is below the right side of the transport unit 2. When the maintenance unit 4 performs maintenance, the maintenance unit 4 is developed on the transport unit 2 and moved upward together with the transport unit 2 after the transport unit 2 has moved to the lower retreat position in FIG. It is moved to the maintenance position indicated by the broken line. The maintenance position is between the transport unit 2 and the inkjet head 31.

  As shown in FIGS. 2 to 5, the maintenance unit 4 includes an ink receiving member 41, a drive unit 42, a wiper unit 43, a motor 44 of the maintenance unit 4, and an upper and lower motor 45 of the transport unit 2.

  The ink receiving member 41 receives ink or the like removed by maintenance. The ink receiving member 41 is formed in a rectangular parallelepiped shape and holds each member of the maintenance unit 4. A recess 41 a for receiving ink or the like is formed at the center of the ink receiving member 41. The recess 41a is formed so as to be larger than the region where the inkjet head 31 is disposed in plan view. The upper side of the ink receiving member 41 is opened.

  The drive unit 42 moves the wiper unit 43 in the front-rear direction during maintenance. The drive unit 42 includes a wiper drive motor 421, a drive belt 422, a pair of drive pulleys 423a and 423b, and a pair of ball screws 424a and 424b.

  The wiper drive motor 421 generates a rotational drive force, and includes a stepping motor or the like, and is disposed outside the rear wall of the ink receiving member 41. The rotation direction of the wiper drive motor 421 can be switched, and the wiper drive motor 421 is moved forward when the wiper drive motor 43 is moved forward, and the wiper drive motor when the wiper drive 43 is moved backward. The rotation direction of 421 is the reverse rotation direction.

  The wiper drive motor 421 has an output gear 421a, and the output gear 421a transmits the rotational drive force of the wiper drive motor 421 to the drive belt 422. The output gear 421a is disposed at the center of the drive belt 422. The driving belt 422 transmits the rotational driving force transmitted from the wiper driving motor 421 to the driving pulleys 423a and 423b. The drive belt 422 is stretched between the drive pulley 423a and the drive pulley 423b.

  The pair of drive pulleys 423a and 423b transmit the rotational driving force transmitted from the drive belt 422 to the ball screws 424a and 424b. The driving pulley 423a and the driving pulley 423b are arranged at the same height with a predetermined interval in the front-rear direction. The drive pulleys 423a and 423b are rotatably supported inside the rear wall of the ink receiving member 41.

  The ball screws 424a and 424b move the wiper portion 43 in the front-rear direction by the rotational driving force transmitted from the wiper drive motor 421. The ball screws 424a and 424b are provided over substantially the entire length of the recess 41a in the front-rear direction. The rear ends of the ball screws 424a and 424b are fixed to the front ends of the drive pulleys 423a and 423b, respectively. The front ends of the ball screws 424a and 424b are rotatably supported by the front wall of the ink receiving member 71. Thereby, ball screw 424a, 424b rotates with drive pulley 423a, 423b, respectively, and moves wiper part 43 back and forth.

  The wiper unit 43 wipes the ink discharge surface (nozzle formation surface) 311a of the unit head 311 of the inkjet head 31 and removes ink, dust, etc. adhering to the ink discharge surface 311a and performs maintenance. 431 and a wiper blade 432 which is an ink wiping member of the present invention.

  The mounting base 431 is to which the wiper blade 432 is attached, and is composed of a prismatic member elongated in the left-right direction.

The mounting base 431 is formed with a pair of screw holes 431a and 431b. Ball screws 424a and 424b are passed through and screwed into the screw holes 431a and 431b. Accordingly, when the ball screws 424a and 424b are rotated, the mounting base 431 moves in the front-rear direction.

  The wiper blade 432, which is an ink wiping member, removes ink, dust, and the like by sliding on the ink ejection surface 311a of the unit head 311 of the inkjet head 31, and cleans the ink ejection surface 311a. The wiper blade 432 is made of an elastically deformable material such as fluorine rubber. The wiper blade 432 is formed in an elongated rectangular thin plate shape.

  As shown in FIG. 2, the length of the wiper blade 432 is not less than the length in the left-right direction of the range in which the unit head 311 is disposed. Note that the wiper blade 432 of the present embodiment is not less than the length in the left-right direction of the range in which the unit heads 311 are arranged as shown in FIG. One wiper blade may be provided for each row of unit heads 311.

The lower end portion of the wiper blade 432 is fixed to the front side surface of the mounting base 431 by a fixture (not shown). As shown in FIG. 4, the upper end portion of the wiper blade 432 is configured to be higher than the upper surface of the mounting base 431, and is usually higher than the ink discharge surface 311a of the unit head 311 at the maintenance position. Are arranged as follows. Accordingly, when the wiper blade 432 moves in the front-rear direction and comes into contact with the unit head 311, it is elastically deformed and slides on the ink ejection surface 311a.

  In the embodiment according to the present invention, for example, the height of the wiper blade 432 can be adjusted in the vertical direction by changing the overall height of the maintenance unit 4 using the vertical motor 45 or the like.

  The motor 44 moves the maintenance unit 4 between the storage position shown in FIG. 1 and the unfolded position shown in FIG.

  The vertical motor 45 moves the maintenance unit 4 up and down together with the transport unit 2. Thus, the vertical motor 45 moves the transport unit 2 to the printing position shown in FIG. 1, the retracted position shown in FIGS. 7 and 8 described later, and the maintenance position shown in FIG. 9, while the maintenance unit 4 is moved to FIG. While moving between the deployment position shown and the maintenance position shown in FIG. 9, the height of the wiper blade 432 is adjusted in the vertical direction as described above.

  As shown in FIG. 5, the inkjet image forming apparatus 1 according to the embodiment of the present invention includes pressurization units 5C, 5K, 5M, and 5Y, a storage unit 6, an operation panel unit 7, and a control unit 8. With.

  The pressurizing units 5C, 5K, 5M, and 5Y pressurize paths for supplying ink from ink bottles (not shown) of the respective colors to the ink jet heads 31C, 31K, 31M, and 31Y, and include pumps and the like. The pressure units 5C, 5K, 5M, and 5Y discharge the ink by pressurizing the path for supplying the ink to the inkjet heads 31C, 31K, 31M, and 31Y when performing the purge for forcibly discharging the ink during the maintenance operation. Let

  The storage unit 6 is a non-volatile storage medium such as a hard disk, and a program for comprehensively controlling the operation of the entire inkjet image forming apparatus 1 and a program for executing a maintenance operation according to the present invention to be described later are stored in advance. In addition to being stored, predetermined conditions such as first and second thresholds described later when executing the maintenance operation are set and stored by the user or the like.

  The operation panel unit 7 includes various operation buttons, a touch panel (none of which is shown), receives an input operation by the user, and outputs an operation signal corresponding to the operation.

  The control unit 8 includes a CPU, a memory (both not shown), and the like, and controls the overall operation of the inkjet image forming apparatus 1 by executing a program stored in the storage unit 6. At the same time, a maintenance operation is executed.

  Next, a cleaning operation in the inkjet image forming apparatus 1 according to the embodiment of the present invention will be described with reference to a flowchart.

  FIG. 6 is a flowchart showing the procedure of the cleaning operation in the inkjet image forming apparatus 1 according to the embodiment of the present invention.

  As shown in FIG. 6, in the inkjet image forming apparatus 1, when the power is turned on, or after the power is turned on, the control unit 8 issues a maintenance execution command by printing a predetermined number of sheets or operating for a predetermined time. It is determined whether it has occurred (S101).

  In step S101, when a maintenance execution command is generated (in the case of YES), the control unit 8 first determines whether or not the maintenance execution command satisfies a predetermined condition. Here, the control unit 8 presets two predetermined conditions based on, for example, the elapsed time from the previous maintenance operation. Specifically, as the first predetermined condition, it is determined whether or not the elapsed time from the previous maintenance operation has exceeded a first threshold such as several days (for example, one week or two weeks), As the predetermined condition 2, it is determined whether or not the elapsed time from the previous maintenance operation has exceeded a second threshold value such as several months. Note that there is a relationship of first threshold <second threshold.

  That is, when a maintenance execution command is generated (S101 “YES”), the control unit 8 first has a first predetermined condition, that is, an elapsed time from the previous maintenance operation for several days (for example, one week) or the like. It is determined whether or not the first threshold is exceeded (S103). Here, when the elapsed time from the previous maintenance operation does not exceed the predetermined first threshold value (S103 “NO”), the control unit 8 determines when the power of the inkjet image forming apparatus 1 is turned on or the user It is a normal maintenance process that is determined to be a maintenance execution command when a predetermined number of sheets are printed in a state where the maintenance command from the previous time or the elapsed time from the previous maintenance operation does not exceed the first threshold value. A normal wipe process at the second speed V2 is executed (S105).

<Normal wipe process in S105>
Here, the normal wiping process in step S105 will be specifically described.

  First, the control unit 8 drives the up / down motor 45 to move the transport unit 2 from the printing position to the lower retreat position as shown in FIG. 7, and then drives the motor 44, as shown in FIG. 8. Then, the maintenance unit 4 is moved from the storage position to the deployed position between the head unit 3 on the upper left side in FIG.

  Thereafter, the control unit 8 drives the vertical motor 45 and the like to move the transport unit 2 from the retracted position to the upper maintenance position as shown in FIG. Thereby, the maintenance unit 4 moves from the deployment position to the maintenance position. Here, when the maintenance unit 4 moves to the maintenance position, as shown in FIG. 2, the wiper blade 432 is arranged on the rear side of the rearmost unit head 311 in the front-rear direction of the inkjet head 31 in FIG. Yes.

  When the movement of the maintenance unit 4 to the maintenance position is completed, the control unit 8 causes the pressure units 5C, 5K, 5M, and 5Y to discharge ink from the inkjet heads 31C, 31K, 31M, and 31Y by purging. On the other hand, it controls to pressurize the path for supplying ink. As a result, as shown in FIGS. 10A and 10B described later, ink of each color is pushed out from the plurality of nozzles 311b formed on the ink ejection surface (nozzle formation surface) 311a of each unit head 311 and adjacent to each other. The ink discharged from the plurality of nozzles 311b is combined to form ink droplets 9 on the ink discharge surface 311a.

  Next, the control unit 8 drives the wiper drive motor 421 in the forward rotation direction so that the wiper blade 432 moves at a predetermined second speed V2. Thereby, the rotational driving force of the wiper drive motor 421 rotates the ball screws 424a and 424b. As a result, the wiper blade 432 moves forward at the second speed V2 as shown in FIG. 2 together with the mounting base 431 screwed into the ball screws 424a and 424b.

  Then, as shown in FIG. 10A, the tip (upper part) of the wiper blade 432 protrudes above the ink discharge surface 311 a of the unit head 311, so that the tip of the wiper blade 432 is aligned with the unit head 311. The ink ejection surface 311a of the unit head 311 is slid at a predetermined second speed V2 while being elastically deformed by being pressed by the ink ejection surface 311a.

  As described above, in the normal wiping process in step S105, the tip of the wiper blade 432 is pressed by the ink discharge surface 311a of each unit head 311 and moved at the second speed V2 while being elastically deformed, thereby purging. The ink droplet 9 attached to the ink discharge surface 311a is removed together with dust or the like attached to the ink discharge surface 311a.

  Here, when the first threshold value such as one week or two weeks or the second threshold value such as several months elapses from the previous maintenance operation, the ink attached to the wiper blade 432 is dried and solidified, dust or the like May adhere to the wiper blade 432. If the normal wiping process in step S105 is performed in such a state, the tip of the wiper blade 432 is elastically deformed and is in contact with the ink discharge surface 311a, so that the ink repellent film on the ink discharge surface 311a is scratched. Or the old ink thickened by the wiper blade 432 may be retransferred to the ink ejection surface 311a of the unit head 311 and a good image may not be obtained.

  For this reason, the control unit 8 of the inkjet image forming apparatus 1 according to the embodiment of the present invention not only when the power is turned on or when the user inputs a maintenance instruction as a maintenance execution command, but also from the previous maintenance operation. Is also input, whether or not the elapsed time from the previous maintenance operation exceeds the first threshold such as one week or two weeks (S103), and the second that the elapsed time is several months It is determined whether or not the threshold value is exceeded (S107).

  Here, although the elapsed time from the previous maintenance operation exceeds the first threshold such as one week or two weeks (S103 “YES”), the control unit 8 determines that the elapsed time is the second such as several months. Is not exceeded (S107 “NO”), the unit head 311 is wiped by the wiper blade 432 to which ink or dust that has dried and solidified due to the elapsed time from the previous maintenance operation exceeding the first threshold. The speed change wiping process is executed so as not to damage the ink ejection surface 311a (S111).

<Speed change wipe process in S111>
Here, the speed change wipe process in step S111 will be specifically described.

  FIG. 11 is an explanatory diagram schematically showing the speed change wipe process of S111, and FIG. 12 is a view showing the relationship between the moving speed and position of the wiper blade 432 in the case of the speed change wipe process.

  In the speed change wiping process in step S111, the controller 8 first rotates the wiper drive motor 421 to move the wiper blade 432 to the second speed as in the normal wipe process in step S105 described above, as shown in FIG. Move with V2.

  Then, at time t1, when approaching the first unit head 311 in the first row, the rotational speed of the motor 44 is decreased and the tip of the wiper blade 432 comes into contact with the first unit head 311 in the first row. Deceleration is made to the first speed V1, which is lower than the second speed V2. Here, the first speed V1 does not damage the ink-repellent film even if the tip of the elastically deformed wiper blade 432 slidably contacts the ink discharge surface 311a of the unit head 311, and adversely affects ink discharge. The speed is not given.

  At time t3, when the tip of the wiper blade 432 comes into contact with the ink discharge surface 311a of the first unit head 311 in the first row, the control unit 8 causes the wiper blade 432 to touch the ink discharge surface 311a of the unit head 311. In the case of FIG. 10B, the nozzle 311b that is closest to the maintenance start position in FIG. 10B is moved at the first speed V1 until reaching the leftmost nozzle 311b that is closest to the wiper blade 432, and the wiper blade 432 It is temporarily stopped at time t5 when the tip reaches the leftmost nozzle 311b. Then, in the vicinity of the nozzle 311b, the first ink droplet 9 closest to the maintenance start position combined with the ink ejected from the adjacent nozzle 311b is formed. The wiper blade 432, which is a wiping member, becomes wet. Here, whether or not the wiper blade 432 has reached the nearest nozzle 311b from the maintenance start position formed on the ink ejection surface 311a of the unit head 311 depends on the number of pulses to the wiper drive motor 421 including a stepping motor or the like. Can be specified.

  Note that the pause process at time t5 when the tip of the wiper blade 432 reaches the nearest nozzle 311b from the maintenance start position is optional, and may be omitted in the present invention. However, if this temporary stop process is omitted, the tip of the wiper blade 432 reaches the nearest nozzle 311b from the maintenance start position in order to ensure ink wetting to the tip of the wiper blade 432, and the first ink After contacting the droplet 9, the wiper blade 432 may be moved at the first speed V1 by a short distance.

  As described above, according to the speed change wipe process in step S111, the elapsed time from the previous maintenance operation exceeds the first threshold value such as one week or two weeks, and the ink that has dried and solidified on the wiper blade 432 Even if dust or the like is attached, it is normal from the time point t3 when the tip of the wiper blade 432 contacts the ink ejection surface 311a of the first unit head 311 in the first row to the time point t5 when reaching the nearest nozzle 311b. It moves at the first speed V1 that is lower than the second speed V2 of the wiping process, and stops temporarily at the time t5 when the tip reaches the nozzle 311b closest to the maintenance start position. The contact surface at the tip of the wiper blade 432 can be wetted by the first ink droplet 9 thus formed.

  At time t5, when the contact surface at the tip of the wiper blade 432 shifts to the wet state by the first ink droplet 9, the control unit 8 increases the rotational speed of the motor 44 to increase the movement speed of the wiper blade 432. The wiping process is performed while gradually increasing to the second speed V2.

  As described above, in the speed change wipe process of step S111, as shown in FIGS. 11 and 12, when the tip of the wiper blade 432 approaches the first unit head 311 in the first row, the second speed V2 is reached. Decreasing to a first speed V1 lower than that, the time t5 when the tip of the wiper blade 432 comes into contact with the ink ejection surface 311a of the first unit head 311 in the first row reaches the first nozzle 311b. After moving to the first speed V1 which is lower than the second speed V2 of the normal wiping process and reaching the nozzle 311b, it is temporarily stopped and the contact surface at the tip is made wet. The wiping process is performed while gradually increasing to the second speed V2, which is a speed higher than the first speed.

  As a result, even if the ink discharge surface 311a of the unit head 311 is maintained after the first threshold value such as one week or two weeks has elapsed since the previous maintenance operation, the tip of the wiper blade 432 is sufficiently wetted before the ink is discharged. Since the maintenance of the discharge surface 311 a is started, the maintenance operation is performed in a state where the ink attached to the wiper blade 432 is dried and solidified, or dust or the like is attached to the wiper blade 432. Even so, it is possible to prevent the ink discharge surface 311a of the unit head 311 from being damaged as much as possible.

  In the embodiment according to the present invention, as shown in FIG. 2 and FIG. 3, each color inkjet head 31 is composed of six unit heads 311 arranged in a staggered matrix of 2 columns × 3 rows. Therefore, the tip of the wiper blade 432 reduces the moving speed of the wiper blade 432 to the first speed V1 for the first unit head 311 in the first row of the inkjet head 31 of each color, and the first ink droplet It moves at the first speed V1 until it reaches 9, and after reaching the first ink droplet 9, it moves while gradually rising to the second speed V2 to perform the wiping process.

  That is, when the wiper blade 432 moves, it reaches the leading end of the first unit head 311 in the second row adjacent to the first unit head 311 in the second row before reaching the rear end of the first unit head 311 in the first row.

  Therefore, as shown in FIG. 12, at the time t7, the moving speed of the wiper blade 432 is also reduced to the first speed V1 for the first unit head 311 in the second row adjacent thereto, and two rows from the time t9. The first unit head 311 of the eye moves at the first speed V1 until time t11 when it reaches the first nozzle 311b.

  At time t11, after reaching the first nozzle 311b of the first unit head 311 in the second row, the wiping process is performed while gradually increasing to the second speed V2, and the second and subsequent units in each row are performed. For the head 311, the wiping process is executed at the second speed V <b> 2.

  In addition, when the wipe process by the wiper blade 432 is reciprocally executed a plurality of times such as two or three times continuously, if the speed change wipe process is executed only once, the tip of the wiper blade 432 is Since it is sufficiently wet, the normal wipe process at the second speed V2 is executed in the same manner as in step S105 for the remaining wipe process.

<Non-contact wipe process of S109>
Next, the non-contact wipe process in step S109 will be specifically described.

  In the flowchart shown in FIG. 6, the elapsed time from the previous maintenance operation exceeds the first threshold such as 1 week or 2 weeks (S103 “YES”), and the elapsed time is several months or the like. If it is determined that the threshold value 2 is also exceeded (S107 “YES”), the ink or dust that has dried and solidified due to the elapsed time from the previous maintenance operation exceeding the second threshold value is wiped to the wiper blade 432. Since the possibility of adhesion is high, the control unit 8 executes the non-contact wiping process at least once so that the wiper blade 432 does not damage the ink ejection surface 311a of the unit head 311 (S109), and thereafter The above-described speed change wipe process in step S111 is executed.

  FIG. 13 is an explanatory diagram showing the state of the non-contact wipe process in step S109.

  As shown in FIG. 13, the non-contact wipe process in step S109 differs from the normal wipe process at the second speed V2 in step S105 shown in FIG. 10 and the speed change wipe process in step S111 shown in FIG. The controller 8 drives the vertical motor 45 and the like to lower the entire maintenance unit 4 relative to the head unit 3 so that the tip of the wiper blade 432 is in a non-contact state away from the ink ejection surface 311a of the unit head 311. And move at the second speed V2 or the like.

  Therefore, even if the ink discharge surface 311a of the unit head 311 is maintained after the second threshold value such as several months has passed since the previous maintenance operation, the tip of the wiper blade 432 is in contact with the ink discharge surface 311a of the unit head 311. Since it moves in a non-contact state, the tip of the wiper blade 432 can be sufficiently moistened without damaging the ink repellent film on the ink ejection surface 311a.

  In the non-contact wiping process in step S109, the tip of the wiper blade 432 is away from the ink ejection surface 311a of the unit head 311. Therefore, the ink droplet 9 cannot be sufficiently wiped off.

  Therefore, here, after the non-contact wipe process of step S109 is executed at least once, the speed change wipe process of step S111 described above is executed as shown in FIG. However, when the speed change wipe process of step S111 is executed, the tip of the wiper blade 432 is already wetted by the ink droplets 9 on the ink ejection surface 311a of the unit head 311 in the non-contact wipe process of step S109. The pause process for temporarily stopping when the tip of the wiper blade 432 reaches the first nozzle 311b may be omitted. By omitting the temporary stop process, the overall maintenance process time can be shortened and the control of the control unit 8 can be simplified.

  Further, since the tip of the wiper blade 432 is in a wet state in the non-contact wipe process in S109, the non-contact wipe process in S109 is executed at least once, and then the normal change in step S105 is performed instead of the speed change wipe process in step S111. A wipe process may be executed. When the non-contact wipe process of S109 is executed at least once and then the normal wipe process of step S105 is executed, the control by the control unit 8 becomes easier than when the speed change wipe process of step S111 is executed. Maintenance time can be shortened.

  Thus, according to the inkjet image forming apparatus 1 of the embodiment of the present invention, when the first threshold value such as several days (for example, one week or two weeks) has been exceeded since the previous maintenance operation, the wiper blade 432 is used. Until the nozzle 311b that is closest to the maintenance direction from the maintenance start position moves at the first speed V1 to wet the wiper blade 432 by the first ink droplet 9, and thereafter is faster than the first speed V1. The wiper blade 432 is moved at the second speed V2 to wipe the ink droplets 9 discharged from the plurality of nozzles of the head unit 3, and the speed change wipe process in step S111 is performed. 432 causes the ink ejection surface 311a to be damaged, or old ink thickened by the wiper blade 432 is Prevented from being retransferred to the ink ejection surface 311a of the de 311, it is possible to form a good image.

  In particular, in the inkjet image forming apparatus 1 according to the embodiment of the present invention, when the wiper blade 432 reaches the first nozzle 311b in the unit head 311, the wiper blade 432 stops for a predetermined time. The wiper blade 432 can be reliably wetted. Therefore, it is possible to prevent the ink ejection surface 311a from being scratched or to retransfer old ink to the ink ejection surface 311a more than when not stopping for a predetermined time.

  Further, in the inkjet image forming apparatus 1 according to the embodiment of the present invention, if the second threshold value such as several months has been exceeded since the previous maintenance operation, before executing the speed change wipe process in step S111, etc. Since the tip of the wiper blade 432 is moved in a non-contact state separated from the ink discharge surface 311a of the unit head 311, the ink discharge surface 311a is scratched and old ink retransfer to the ink discharge surface 311a is more reliably prevented. can do.

  In the above embodiment, as shown in FIGS. 2 and 3, the inkjet heads 31 of the respective colors are composed of six unit heads 311 arranged in a staggered matrix of 2 columns × 3 rows. Therefore, in the speed change wiping process in step S111, as shown in FIG. 12, the tip of the wiper blade 432 determines the moving speed of the wiper blade 432 for the first unit head 311 in the first row of the inkjet head 31 of each color. The first speed V1 is decelerated to the first speed V1 until the closest nozzle 311b is reached from the maintenance start position, and after the wiper blade 432 reaches the nearest nozzle 311b, the second speed V2 is gradually increased. The wipe unit performs the wiping process while moving the first unit head 311 adjacent to the second row in the same manner. Perform changes wiping operation, the unit head 311 of the second and subsequent columns have been described to perform the wiping operation at the second speed V2 is not limited thereto.

  FIG. 14 is an explanatory diagram showing another example of the relationship between the speed and position of the wiper blade in the speed change wipe process in the inkjet image forming apparatus according to the embodiment of the present invention.

  As shown in FIG. 14, for example, at time t11, the moving speed of the wiper blade 432 is changed from the second speed V2 to the tip of the wiper blade 432 for the first unit head 311 in the first row of the inkjet heads 31 of each color. Is decelerated to the first speed V1 by time t13 when it contacts the ink ejection surface 311a of the first unit head 311 in the first row.

  Then, it moves at the first speed V1 from the time t13 to the time t15 when it reaches the first nozzle 311b. After reaching the time t15, the first speed in the second row next to it is maintained at the first speed V1. The unit head 311 moves to the time point t17 when it reaches the first nozzle 311b, and after reaching the time point t17, the wiping process is executed for the second and subsequent unit heads 311 in each row while gradually increasing to the second speed V2. You may do it. Thereby, control can be simplified.

  However, in the speed change wipe process shown in FIG. 12, after reaching the first nozzle 311b in the first unit head 311 in the first row, the wipe process is performed while gradually increasing to the second speed V2. As a whole, the maintenance time is faster than the speed change wiping process shown in FIG. 14 which moves until the first nozzle 311b of the first unit head 311 in the second row adjacent to the first speed V1 remains at the first speed V1.

  In the above embodiment, the speed change wipe process in step S111 is performed by comparing the elapsed time from the previous maintenance operation with the first threshold value and the second threshold value (second threshold value> first threshold value). Or the non-contact wipe process in step S109 has been described. However, the present invention is not limited to this, and the number of prints from the previous maintenance operation is determined based on the first threshold value and the second threshold value (first threshold value). Of course, the speed change wipe process in step S111 may be executed as compared with (threshold value 2> first threshold value), or the non-contact wipe process in step S109 may be executed.

  Moreover, in the said embodiment, although demonstrated with the example provided with the four inkjet heads 31C, 31K, 31M, and 31Y, the number of inkjet heads is not restricted to this, What is necessary is just two or more.

  Moreover, in the said embodiment, although the example which the wiper part 43 moves with respect to the fixed inkjet head 31 was shown, not only this but the wiper part 43 moves relatively with respect to the inkjet head 31 If it is.

DESCRIPTION OF SYMBOLS 1 ... Inkjet image forming apparatus 2 ... Conveying part 3 ... Head unit 4 ... Maintenance unit 5 ... Pressurizing part 6 ... Storage part 7 ... Operation panel part 8 ... Control part 31 ... Inkjet head 41 ... Ink receiving member 42 ... Drive part 43 ... Wiper part 44 ... Motor 45 ... Vertical motor 311 ... Unit head 311a ... Ink ejection surface 311b ... Nozzle 314 ... Discharged ink holding part 432 ... Wiper blade (ink wiping member)

Claims (3)

An inkjet head that ejects ink from an ink ejection surface on which a plurality of nozzles are formed;
A controller that controls the ink discharge surface after the ink is discharged from the ink discharge surface during maintenance to be wiped along the ink discharge surface by an ink wiping member;
The controller is
The ink wiping member is brought into contact with the ink ejection surface during maintenance and moved at a first speed at least until reaching the nozzle closest to the maintenance start position, and then the speed is higher than the first speed. An inkjet image forming apparatus, wherein the ink wiping member is controlled to move at a second speed. The controller is
During the maintenance at the first speed, the ink wiping member is stopped for a predetermined time when the nozzle closest to the maintenance start position is reached, and the ink wiping member is moved at the second speed after the predetermined time has stopped. The inkjet image forming apparatus according to claim 1, wherein: The controller is
Prior to moving the ink wiping member at the first speed during the maintenance, the tip of the ink wiping member is brought into contact with the ink droplet on the ink ejection surface, but is not brought into contact with the ink ejection surface. The inkjet image forming apparatus according to claim 1, wherein a non-contact ink wiping process for wiping ink on the ink ejection surface in a non-contact state is executed.

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