JP2014079977A - Image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image formation device that prevents the occurrence of a paper jam and damage to a recording head, has reduced power consumption, and can perform high-quality recording.SOLUTION: A guide is provided so as to cover a recording medium to be conveyed on a route of a conveyance belt that is a portion before the recording medium has reached a recording head.

Description

  The present invention relates to an image forming apparatus that records an image on a recording medium by an inkjet recording method.

  A conventional inkjet recording apparatus binarizes image data transmitted from a host personal computer and forms an image on a recording medium by an arithmetic processing unit, and records the data on the recording medium based on the binarized image data. An image is recorded by ejecting ink from the head. Hereinafter, the suction conveyance unit in the prior art will be described. In the structure described in Patent Document 1, a belt is transported immediately below the recording head, and the sheet is transported in the downstream direction by the belt while being attracted from the lower surface to the lower surface of the sheet by the electrostatic adsorption belt. As a result, the distance from the recording head to the surface of the paper is stabilized, and the image quality of the printed matter is maintained. Further, in Patent Document 2, a suction fan is used as an adsorbing force for adsorbing the belt. This suction fan has a plurality of suction forces in the surface to be sucked, and sucks a paper edge portion where a paper curl is likely to occur with a large suction force. Further, in Patent Document 3, the curl formed on the left and right ends of the roll paper is pressed with a guide so that the print portion is not affected by the curl.

JP 2006-246932 A JP 2010-228262 A JP 2011-218749 A

  During recording, the recording medium must be in close contact with the conveying belt immediately below the recording head. If the recording medium is lifted from the conveyor belt due to the effect of curling or the like, the end of the paper may come into contact with the recording head, resulting in a paper jam (jamming), or in the worst case, the recording head may be damaged. To do. In Patent Document 2, curling is forcibly suppressed by pulling a paper edge portion (left and right side curl portions) where curling occurs with a large suction force. However, with this method, the negative pressure must be increased according to the size of the curl. A large suction force not only consumes a large amount of power, but also adversely affects the recorded image. Further, in Patent Document 3, the roll paper is pressed by a cover, but there is a problem that a negative pressure has to be increased because a cover in the transport direction is not provided and suction efficiency is not good.

  Accordingly, an object of the present invention is to realize an image forming apparatus that can prevent a paper jam and damage a recording head, and can perform high-quality recording with low power consumption.

  Therefore, the image forming apparatus of the present invention is an image forming apparatus that performs recording by ejecting ink from a recording head onto a recording medium conveyed in close contact with a conveying belt provided in the conveying unit. Is sucked from the direction opposite to the conveying surface on which the conveying belt conveys the recording medium, thereby bringing the recording medium into close contact with the conveying belt, and the conveying unit in the conveying direction for conveying the recording medium. A guide is provided upstream of the recording head and on the conveying surface side of the conveying belt so as to surround both side portions and the upper portion of the conveyed recording medium and to limit a space around the recording medium. And

  According to the present invention, the conveying unit of the image forming apparatus causes the recording medium to adhere to the conveying belt by sucking the recording medium from the direction opposite to the conveying surface on which the conveying belt conveys the recording medium. The conveyance unit of the image forming apparatus is on the upstream side of the recording head in the conveyance direction for conveying the recording medium, and surrounds the both side portions and the upper part of the conveyed recording medium on the conveyance surface side of the conveyance belt. A guide for limiting the space around the medium is provided. As a result, it is possible to realize an image forming apparatus that can prevent paper jams and damage the recording head, and can perform high-quality recording with low power consumption.

1 is a schematic view showing an internal structure of an image forming apparatus according to the present invention. FIG. 2 is a block diagram illustrating a control system of the ink jet recording apparatus of FIG. 1. It is a cross-sectional perspective view of the conveyance part which can apply this embodiment. It is a perspective view of the conveyance part in which the upper guide and the horizontal guide were provided. It is the perspective view shown so that a horizontal guide could be understood by removing the upper guide of a conveyance part. It is the figure which showed the cross section of the conveyance part. It is the figure which showed the cross section of the conveyance part.

  Embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic view showing the internal structure of an image forming apparatus (hereinafter also referred to as an ink jet recording apparatus) 1 according to the present invention. Hereinafter, the configuration and operation of the inkjet recording apparatus 1 will be described with reference to FIG. The ink jet recording apparatus 1 is a so-called line type ink jet recording apparatus that performs recording by ejecting ink from a fixed recording head onto a transported recording medium. The ink jet recording apparatus 1 includes a paper feeding unit 10, a belt suction conveyance unit (hereinafter also simply referred to as a conveyance unit) 20, a head unit unit 30, a paper discharge unit 40, and the like. The paper feed unit 10 includes a paper feed tray 11 that stores and stacks the recording media P, a take-out means 12 that takes out the recording media P from the paper feed tray 11 one by one, and a recording medium P that is taken out by the take-out means 12. And a first transport roller 25 that sandwiches and transports the transport unit 20 to the transport unit 20. The recording medium P is in the form of a cut sheet such as plain paper, recycled paper, glossy paper, thick paper, and the like, and is in close contact with the transport belt by electrostatic adsorption during transport.

  The transport unit 20 disposed above the paper feed unit 10 includes a first guide member 26 that guides the recording medium P transported from the first transport roller 25 toward the second transport roller 27. Further, the transport unit 20 includes an endless transport belt 21 that supports the recording medium transported from the second transport roller 27 and transports the recording medium in the transport direction (arrow X direction). Further, the transport unit 20 includes a pressing roller 24 that presses the recording medium transported from the second transport roller 27 onto the transport belt 21, and a third transport roller 29 that transports the recording medium from the transport belt 21 to the paper discharge unit 40. Yes. The conveyor belt 21 is stretched by a plurality of stretching rollers 23 and a driving roller 22 that rotates the conveyor belt 21. At an image recording position where an image is formed on the recording medium P conveyed by the conveying belt 21, a head unit 30 for ejecting ink and recording an image on the recording medium P is provided.

  The head unit 30 that performs recording by the ink jet method is arranged on the upper portion of the transport belt 21 and includes the following recording heads in order along the transport direction of the recording medium. The unit 30 includes a black ink recording head 31, a cyan ink recording head 32, a magenta ink recording head 33, and a yellow ink recording head 34 (FIG. 2 described later). , See FIG. Each recording head is provided with a plurality of nozzles that eject ink onto the recording medium P. As a method for ejecting ink onto the recording medium P, there are a bubble jet method and a piezo method. The bubble jet method is a method in which ink in the vicinity of the heater is boiled by using a heater that generates heat when energized, and ink in the nozzle is discharged from the nozzle outlet to the outside of the nozzle. The piezo method is a method of changing the ink volume in the nozzle by using a piezo element (piezoelectric element) that deforms when a voltage is applied, and discharging the ink in the nozzle from the nozzle outlet to the outside of the nozzle.

  By the above method, ink is ejected from the head unit 30 onto the recording medium P, and an image is recorded on the recording medium P. Thereafter, the recording medium P is sequentially discharged to the paper discharge unit 40.

  FIG. 2 is a block diagram showing a control system of the inkjet recording apparatus 1 of FIG. Recording information and commands transmitted from the host PC (host device) 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 information of the recording apparatus 10, recording operation, handling of the recording medium 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. In the operation process performed 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 each head unit 30 is moved away from the cap 50 to the recording position. Further, as will be described later, the CPU 100 performs control for correcting the rotation of the fan motor of the fan for applying an appropriate negative pressure to the head unit 30 as needed based on pressure information obtained by the pressure sensor. Further, the CPU 100 controls the roll motor 126 that feeds the recording medium P through the output port 114 and the motor driving unit 116, the transport motor 120 that transports the recording medium P, and the like to transport the recording medium P to the recording position. .

  When recording is performed, the leading edge detection sensor 109 detects the leading edge position of the recording medium P in order to determine the timing (recording timing) of ejecting ink onto the recording medium P conveyed at a constant speed. Thereafter, in synchronization with the conveyance of the recording medium P, the CPU 100 sequentially reads the recording information from the image memory 106 and transfers the read recording information to each head unit 30 via the head unit control 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 processing programs and tables corresponding to the control flow. The CPU 100 uses a work RAM 108 as a working memory. Further, the CPU 100 drives the pump motor 124 via the output port 114 and the motor drive unit 116 during the cleaning and recovery operations of each head unit 30, and controls the pressurization and suction of ink.

  The features of the present invention will be described below.

  FIG. 3 is a cross-sectional perspective view of the transport unit 20 to which the present embodiment is applicable. An adsorption fan 50 is provided below the conveyance belt 21 that conveys the recording medium by the conveyance unit 20 (on the conveyance surface that conveys the recording medium). By rotating the adsorption fan 50, the conveyance belt 21 is rotated. A negative pressure is applied to the recording medium P through a plurality of holes provided at equal intervals. In this manner, with the recording medium P adsorbed on the conveying surface side of the conveying belt 21, recording is performed on the recording medium P by conveying the recording medium P to below the recording head and ejecting ink from the recording head.

  The recording medium P is transported to the transport unit 20 in the arrow X direction in accordance with the recording signal. At this time, the recording medium P must be adhered to the conveying surface of the conveying belt 21 immediately before reaching the recording head 30 disposed closest to the recording medium in the conveying direction (arrow X direction). Therefore, in the inkjet recording apparatus of the present invention, the conveyance belt 21 is located between the most upstream portion where conveyance is started and the recording head disposed closest to the recording medium in the conveyance direction (upstream of the recording head). A plurality of guides are provided. An upper guide 51 is provided so as to cover the conveyance belt 21, and a lateral guide 52 is provided so as to surround the left and right ends of the recording medium in the direction intersecting the conveyance direction.

  FIG. 4 is a perspective view of the conveyance unit 20 provided with the upper guide 51 and the lateral guide 52, and FIG. 5 is a perspective view showing the lateral guide 52 by removing the upper guide 51 of the conveyance unit 20. . The lateral guide 52 includes two racks and one gear that engages with the racks. By rotating the gear, the lateral guides on both sides of the conveyance belt can be slid simultaneously. By moving the guide in this way, it is configured to be compatible with a plurality of different types of recording media.

  6 and 7 are cross-sectional views of the transport unit 20. When the recording medium P is transported to the space surrounded by the upper guide 51 and the lateral guide 52, the suction fan 50 is rotated. Then, the recording medium P is brought into close contact with the transport belt 21 by the suction force generated by sucking air in the space surrounded by the upper guide 51 and the lateral guide 52 that are opposed to each other with the suction fan 50 and the transport belt 21 in between. Let At this time, since the space around the recording medium P is limited by being surrounded by the upper guide 51 and the lateral guide 52, the suction of excess air other than the space surrounded by the upper guide 51 and the lateral guide 52 is reduced. In addition, the recording medium P can be brought into close contact with the conveyance belt 21 efficiently.

  Further, as described above, since the upper guide 51 and the lateral guide 52 are provided, the suction effect by the suction fan 50 extends only in the space surrounded by the upper guide 51 and the lateral guide 52. As a result, the airflow at the position where the recording head is cut off from the downstream side in the recording medium conveyance direction is not affected by the suction by the suction fan 50 and does not affect the recording.

  Further, the upper guide 51 is disposed with an inclination as shown in FIG. 7, and is located downstream (in the vicinity of the recording head) with respect to the opening height (distance from the conveyance belt to the guide) of the most upstream portion (upstream in the conveyance direction). It is inclined so that the opening height of the downstream end portion becomes gradually lower. As the curled recording medium is conveyed, the volume of the sucked gas is reduced, which is more efficient. By setting the opening height of the most downstream portion lower than the recording head height, the curled recording medium Prevents contact with the recording head.

  In this way, a plurality of guides are provided so as to cover the recording medium on the path of the conveying belt, which is a portion before the recording medium to be conveyed reaches the recording head. As a result, it is possible to realize an image forming apparatus that can prevent the occurrence of a paper jam and damage the recording head, and can perform high-quality recording with low power consumption.

20 Conveying Section 21 Conveying Belt 30 Head Unit 50 Suction Fan 51 Upper Guide 52 Side Guide

Claims (7)

In an image forming apparatus that performs recording by ejecting ink from a recording head onto a recording medium conveyed in close contact with a conveying belt provided in a conveying unit.
The transport unit sucks the recording medium from the direction of the back surface of the transport surface on which the transport belt transports the recording medium, thereby bringing the recording medium into close contact with the transport belt,
The transport unit is upstream of the recording head in the transport direction for transporting the recording medium, and on the transport surface side of the transport belt,
An image forming apparatus comprising: a guide that surrounds both side portions and an upper portion of the conveyed recording medium and limits a space around the recording medium.   The guide provided at an upper portion of the guide is inclined so that a distance from the conveyor belt gradually decreases from an upstream side to a downstream side in the conveyance direction of the conveyor belt. The image forming apparatus according to 1.   The image forming apparatus according to claim 1, wherein guides on both sides of the recording medium conveyed among the guides are provided so as to be slidable according to the width of the recording medium. apparatus.   The image forming apparatus according to claim 1, wherein the conveyance belt attracts the recording medium to the conveyance belt by electrostatic adsorption.   5. The image forming apparatus according to claim 1, wherein the transport unit sucks the recording medium onto the transport belt by a suction force generated by rotation of a fan.   6. The image forming apparatus according to claim 1, wherein a plurality of holes are opened at equal intervals in the conveyance belt.   The distance from the conveyance belt at the downstream end in the conveyance direction of a guide provided in the upper part of the guide is shorter than the distance between the conveyance belt and the recording head. The image forming apparatus according to claim 6.

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