Image formation device

Abstract

To prevent a paper sheet from being brought into contact with an ink jet head by properly correcting the paper sheet without generating a wrinkle in the paper sheet by partially correcting curling of the paper sheet of a front end part in a paper conveying direction without providing a pair of rollers at a paper curl correction part.SOLUTION: Paper correction arms 14a, 14b (sheet correction means) for correcting a sheet (a paper sheet PA) in a predetermined direction are provided on an upstream side in a sheet conveying direction in an image formation device. The paper correction arms 14a, 14b correct the part of the sheet (the paper sheet PA) on a sheet tip end side in the sheet conveying direction and further on both end sides in a direction orthogonal to the sheet conveying direction by rotating from a standby position to a pressing position.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus that properly straightens paper without causing wrinkles in the paper, thereby preventing the paper from coming into contact with an inkjet head. [Background technology]

[0002] In a line-type image forming apparatus, ink is ejected from the inkjet head based on image data onto paper that is transported by a belt transport unit provided below the inkjet head, thereby performing printing.

[0003] At this time, if deformation such as curling occurs at the edge of the paper being suction-transported, there is a possibility that the deformed paper will collide with the bottom of the inkjet head if the paper continues to be transported as is.

[0004] Therefore, a curl correction unit is generally provided to correct the curl of the paper, which is made up of a pair of soft and hard rollers that sandwich the paper between them.

[0005] Patent document 1 discloses a technology relating to a paper conveying device that has a loop roller that curves the paper upstream of a registration roller, and has a control means that controls whether to stop driving the loop roller or whether to slow down the speed depending on the type of paper when correcting the paper bend. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-285239 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the printing device described in Patent Document 1 controls whether to stop or slow down the drive of the loop roller depending on the paper type when straightening paper curl, so while it can straighten curls for some paper types, it has the problem of causing wrinkles that extend in the transport direction. The printing device described in Patent Document 1 also has the disadvantage of the soft roller wearing out, and there is also the problem that straightening curls is limited to paper that requires it or to the minimum number of locations.

[0008] The present invention has been made in consideration of these problems, and aims to provide an image forming device that can properly correct the paper without causing wrinkles in the paper by partially correcting the paper curl at the leading edge in the paper transport direction without providing a pair of rollers in the paper curl correction section, thereby preventing the paper from coming into contact with the inkjet head. [Means for solving the problem]

[0009] In order to achieve the above object, the image forming apparatus according to the present invention is characterized by: a sheet correcting means for correcting a sheet in a predetermined direction on the upstream side of the sheet conveying direction in the image forming apparatus; The sheet straightening means serves to straighten the portion of the sheet on the leading edge side of the sheet in the sheet conveying direction and on both end sides in the direction perpendicular to the sheet conveying direction. [Effects of the Invention]

[0010] According to the features of the image forming apparatus of the present invention, the paper can be properly straightened without causing wrinkles in the paper, thereby preventing the paper from coming into contact with the inkjet head. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram illustrating the configuration of an inkjet image forming apparatus according to an embodiment of the present invention. [Figure 2] 2 is a perspective view of the vicinity of a registration roller of a paper feed unit of an inkjet image forming apparatus according to an embodiment of the present invention. FIG. [Figure 3]2 is a plan view of the vicinity of a registration roller of a paper feed unit of an inkjet image forming apparatus according to an embodiment of the present invention. FIG. [Figure 4] 4 is a cross-sectional view taken along the line AA in FIG. 3 when a shaft portion included in the inkjet image forming apparatus according to the embodiment of the present invention is in a standby position. [Figure 5] 4 is a cross-sectional view taken along the line AA in FIG. 3 when a shaft portion included in the inkjet image forming apparatus according to the embodiment of the present invention is in a pressing position. [Figure 6] 1 is a diagram showing an example of a sheet of paper that has been flattened by an inkjet image forming apparatus according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same or equivalent parts and components are designated by the same or equivalent reference numerals throughout the drawings. However, it should be noted that the drawings are schematic and may differ from the actual product. Furthermore, the drawings may include parts with different dimensional relationships and ratios.

[0013] Furthermore, the embodiments shown below are merely examples of devices that embody the technical concept of the present invention, and the technical concept of the present invention does not limit the arrangement of each component to that shown below. Various modifications can be made to the technical concept of the present invention within the scope of the claims.

[0014] (Configuration of inkjet image forming apparatus 1) An embodiment of an inkjet image forming apparatus 1, which is an image forming apparatus according to the present invention, will be described in detail below with reference to the accompanying drawings.

[0015] FIG. 1 is a schematic diagram of an inkjet image forming apparatus 1 according to an embodiment of the present invention.

[0016] In the following description, the front side of the paper in FIG. 1 where the user is positioned is referred to as the left side, and the back side of the paper is referred to as the right side. Also, in FIG. 1, up and down as seen from the user are referred to as the up and down direction. Also, the path indicated by the dashed line in FIG. 1 is the transport path R along which paper PA, which is a sheet, is transported. The transport direction of paper PA is referred to as the front-to-rear direction. In the following description, upstream means the front direction, and downstream means the rear direction.

[0017] As shown in FIG. 1, the inkjet image forming apparatus 1 includes a paper feed unit 2, a suction transport unit 3, a printing unit 4, and a paper discharge unit 6.

[0018] The paper feed unit 2 feeds paper PA, which is a print medium, and includes a paper feed tray 11, a paper feed roller 12, and a registration roller 13.

[0019] The paper feed tray 11 is loaded with paper sheets PA to be used for printing.

[0020] The paper feed roller 12 picks up the paper PA stacked on the paper feed tray 11 one by one and transports the paper PA toward the registration roller 13. The paper feed roller 12 is disposed above the paper feed tray 11. The paper feed roller 12 is driven to rotate by a motor (not shown).

[0021] The registration rollers 13 grip and temporarily stop the leading edge of the sheet PA that has been conveyed and struck by the sheet feed rollers 12, and then convey the sheet toward the suction conveyance section 3. The registration rollers 13 are disposed downstream of the sheet feed rollers 12. The registration rollers 13 are rotated by a motor (not shown).

[0022] The suction conveyance unit 3 conveys the paper PA conveyed from the registration rollers 13 toward the printing unit 4 and the paper discharge unit 6. The suction conveyance unit 3 includes a conveyor belt 21, a drive roller 22, driven rollers 23 to 25, a belt drive motor 26, a platen plate 27, and a suction fan 28.

[0023] The conveyor belt 21 is an endless belt that is looped around a drive roller 22 and driven rollers 23 to 25. The conveyor belt 21 has air intake holes, which are through holes for attracting and holding the paper sheets PA, formed at predetermined intervals along the conveying direction of the conveyor belt 21. The conveyor belt 21 attracts and holds the paper sheets PA on the conveyor belt 21 by a negative pressure (attractive force) generated in the air intake holes by driving the suction fan 28.

[0024] 1 by the rotational drive of the drive roller 22. As a result, the conveyor belt 21 moves endlessly to convey the paper PA to the right.

[0025] The conveyor belt 21 is stretched around the drive roller 22 and the driven rollers 23 to 25. The drive roller 22 is driven to rotate by a belt drive motor 26, causing the conveyor belt 21 to rotate. The driven rollers 23 to 25 are driven by the drive roller 22 via the conveyor belt 21. The driven roller 23 is disposed at approximately the same height as the drive roller 22, and spaced a predetermined distance from the drive roller 22 in the left-right direction. The driven rollers 24 and 25 are disposed below the drive roller 22 and the driven roller 23, spaced a predetermined distance from each other in the left-right direction, and at approximately the same height.

[0026] The belt drive motor 26 drives the drive roller 22 to rotate.

[0027] The platen plate 27 is disposed below the conveyor belt 21 between the drive roller 22 and the driven roller 23, and supports the lower surface of the conveyor belt 21 so that it can slide.

[0028] The suction fan 28 is disposed below the platen plate 27 and generates a downward airflow.

[0029] The printing unit 4 prints on the paper PA transported by the suction transport unit 3. The printing unit 4 is provided above the suction transport unit 3. The printing unit 4 is fixed inside a housing (not shown) of the inkjet image forming apparatus 1. The printing unit 4 includes a black (K) inkjet head 31K, a cyan (C) inkjet head 31C, a magenta (M) inkjet head 31M, a yellow (Y) inkjet head 31Y, and a head holder 32.

[0030] Inkjet heads 31K, 31C, 31M, and 31Y print by ejecting ink from nozzles onto paper PA that is being transported while being sucked by suction transport unit 3, thereby enabling printing without gaps in the main scanning direction (left and right direction).

[0031] The head holder 32 holds the inkjet head 31 above the suction transport unit 3. The head holder 32 is formed in a hollow, substantially rectangular parallelepiped shape.

[0032] The paper output unit 6 outputs the paper PA printed by the printing unit 4.

[0033] The control unit 7 controls the paper feed unit 2, the suction transport unit 3, the paper discharge unit 6, and the like that are provided in the inkjet image forming apparatus 1.

[0034] 2 to 5 are diagrams showing the configuration of the vicinity of the registration rollers 13 of the paper feed unit 2 of the inkjet image forming apparatus 1 according to the embodiment of the present invention. Fig. 2 is a perspective view of the vicinity of the registration rollers 13 of the paper feed unit 2, Fig. 3 is a plan view of the vicinity of the registration rollers 13 of the paper feed unit 2, and Figs. 4 and 5 are cross-sectional views of the AA cross section shown in Fig. 3.

[0035] 2 to 5, sheet correction arms 14a and 14b, which are sheet correction means, are provided below registration rollers 13 at positions that do not interfere with upper guide plate 15, which guides sheet PA in the transport direction. Sheet correction arms 14a and 14b are provided on both ends in the rotation axis direction (left and right direction) of registration rollers 13. Sheet correction arm 14a and sheet correction arm 14b have the same configuration, so only sheet correction arm 14b will be described here.

[0036] The sheet correction arm 14b has a shaft portion 14b2 that is rotatable around a rotation axis 14b1 in the direction of rotation F1 or F2. A contact portion 14b3 that comes into contact with the sheet PA is provided at the lower end of the shaft portion 14b2. The contact portion 14b3 is located upstream (in front of) the registration rollers 13 in the front-rear direction (conveyance direction).

[0037] The diagram shown in Figure 4 shows the case where the shaft portion 14b2 is rotated in the F1 direction and is in the standby position, and the diagram shown in Figure 5 shows the case where the shaft portion 14b2 is rotated in the F2 direction and is in the pressing position.

[0038] As shown in Figure 4, when the shaft portion 14b2 is in the standby position, the paper PA transported by the paper feed roller 12 passes between the upper guide plate 15 and the lower guide plate 16 below the contact portion 14b3 without coming into contact with the contact portion 14b3, and then hits the registration roller 13 and is gripped.

[0039] 5, when the shaft portion 14b2 is rotated in the F2 direction to the pressing position, the contact portion 14b3 presses the sheet PA, the leading edge of which is gripped by the registration roller 13, against the lower guide plate 16 from above.

[0040] That is, when the control unit 7 causes the paper feed roller 12 to transport the paper PA and the transported paper PA is stopped by being abutted against the registration roller 13, the control unit 7 rotates the shaft portion 14b2 in the F2 direction so that the contact portion 14b3 presses down from above the leading edge of the paper PA in the transport direction (rearward direction) and both end portions in the direction perpendicular to the transport direction (left-right direction).

[0041] This makes it possible to correct the portions on the leading edge side in the transport direction (rear direction) of the sheet PA and on both end sides in the direction (left and right direction) perpendicular to the transport direction.

[0042] FIG. 6 is a diagram showing an example of a sheet of paper PA that has been flattened by the inkjet image forming apparatus 1 according to an embodiment of the present invention.

[0043] 6, portions PA1 and PA2 on the leading edge of the sheet PA in the transport direction (rearward) and on both ends in the direction perpendicular to the transport direction (left and right) are corrected to face downward. This prevents the leading edge of the sheet PA from coming into contact with the inkjet heads 31K, 31C, 31M, and 31Y even when the sheet PA is transported below the inkjet heads 31K, 31C, 31M, and 31Y by the suction transport unit 3.

[0044] Here, the shaft portion 14b2 is rotated in the F2 direction to push down from above the leading edge of the sheet PA in the transport direction (rearward) and both end portions in the direction perpendicular to the transport direction (left and right), thereby deforming the sheet so that its leading edge faces downward. However, this is not limited to this. For example, the sheet PA may be deformed so that its leading edge faces downward by pushing up from below about 30 mm inward from both side edges at a position about 20 mm from the leading edge of the sheet PA in the transport direction. Furthermore, in addition to the paper correction configuration in which the sheet PA is pushed down from above when its leading edge is held by the registration rollers 13, a member that pushes up from below to make a dent in the sheet may be provided to deform the sheet so that its leading edge faces downward. (Addendum) The present application discloses the following inventions. (Appendix 1) a sheet correcting means for correcting a sheet in a predetermined direction on the upstream side of the sheet conveying direction in the image forming apparatus; The sheet straightening means straightens the portion of the sheet on the leading edge side of the sheet in the sheet conveying direction and on both end sides in the direction perpendicular to the sheet conveying direction. An image forming apparatus characterized by:

[0045] This allows the curl of the paper at the leading edge in the paper transport direction to be partially corrected without providing a pair of rollers in the paper curl correction section, thereby properly correcting the paper without causing wrinkles in the paper and preventing contact with the inkjet head. [Explanation of symbols]

[0046] 1. Inkjet image forming device 2 Paper feed section 3. Suction and transport section 4 Printing Department 6 Paper output section 7 Control Unit 11 Paper feed stand 12 Paper feed roller 13 Registration roller 14a, 14b Paper correction arm 14b1 Rotation axis 14b2 shaft section 14b3 Contact part 15 Upper guide plate 16 Lower guide plate 21 Conveyor belt 22 Drive roller 23~25 Driven roller 26 Belt drive motor 27 Plastic Plate 28 Suction fan 31 Inkjet head 32 Head holder

Claims

[Claim 1] a sheet correcting means for correcting a sheet in a predetermined direction on the upstream side of the sheet conveying direction in the image forming apparatus; The sheet straightening means straightens the sheet at the leading end side in the sheet conveying direction and at both end sides in the direction perpendicular to the sheet conveying direction. An image forming apparatus characterized by:

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