JP2004217331A - Sheet conveying device and ink jet recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet conveying device provided with a constitution capable of maintaining an opposed interval with a printing means to a constant degree by enhancing adhering property to a conveying belt even in a thick sheet. <P>SOLUTION: The sheet conveying device is provided with a constitution that a part of a conveying passage fed from the paper feed part is direction-converted. When a conveying belt 17 for electrostatically adsorbing the sheet is used, a guide part 20 is provided, which is arranged at an outer periphery of a roller 18 wound with the conveying belt 17 and has a guide surface 20A provided with a curved surface or an inclined surface having an angle θ directing a tip end of the sheet toward a flat part formed on the conveying belt 17. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a sheet conveying apparatus and an ink jet recording apparatus, and more particularly, to a sheet conveying mechanism in an ink jet recording apparatus having a reversing path in a sheet conveying path to an image forming area.
[0002]
[Prior art]
As one of the image forming apparatuses, there is a printing apparatus that directly records an image on a conveyed sheet.
2. Related Art As a printing apparatus, an ink jet recording apparatus that prints an image by ejecting ink droplets to a sheet based on image information is known.
The ink jet recording apparatus includes an ink head that discharges ink droplets, and a conveyance path that feeds a sheet toward a printing area, which is an image forming area where the ink head and the sheet face each other, and discharges the sheet from the printing area. May be combined with a sheet conveying device.
On the other hand, the sheet transport path includes not only a path that moves in one direction such as a horizontal direction, but also a configuration in which the direction is changed vertically in the middle from the paper supply unit to the paper discharge unit to reverse and move the sheet. (For example, Patent Document 1).
[0003]
The reason for adopting such a configuration is to save the space of the apparatus.In this case, the paper feed tray and the paper output tray are provided in the vertical direction, and the sheet fed from the paper feed tray is moved in the vertical direction. By changing the direction, the image is reversed and moved to the print area. Further, after printing, a configuration is adopted in which the sheet is moved in the horizontal direction and discharged to a paper discharge tray.
[0004]
By the way, in the print area, it is important that the distance between the sheet and the ink head is accurately defined in order not to deteriorate the image quality. In other words, the interval between the ink head and the ink head is determined by the flatness of the sheet. Therefore, in the sheet conveyance structure, the sheet is suctioned with a negative pressure in the printing area and brought into close contact with the flat plate or the conveyance roller to make contact with the ink head. There has been proposed a configuration for defining an interval between the two (for example, Patent Document 1).
[0005]
As a configuration for negative pressure suction, a configuration has been proposed in which a transport belt is provided that is hung around a pair of rollers and a surface facing the ink head is extended in a horizontal direction, and a sheet is attracted to the transport belt and transported. (For example, Patent Document 2).
[0006]
Apart from negative pressure suction, as a configuration to obtain the flatness of the sheet, that is, a state without waviness and wrinkles, one of the pair of nipping rollers used to feed the sheet to the printing area is used as a sheet pressing roller It is also suggested that the sheet be extended in a state where the sheet is extended so that swelling and wrinkles are not generated by the pressing roller, or that the degree of swelling is detected and the printing process is not performed when the swelling state is higher than a predetermined swelling state. (For example, Patent Document 3).
[0007]
[Patent Document 1]
JP 2000-158637 A (each column of paragraphs “0016”, “0017”, and “0028”)
[Patent Document 2]
JP-A-2000-211762 (paragraph "0019" column, FIG. 2)
[Patent Document 3]
JP 2001-262459 A (each column of paragraphs “0083”, “0094”, and “0104”)
[0008]
[Problems to be solved by the invention]
As a sheet used for the printing process, not only a sheet having a relatively small thickness such as plain paper used for general copying but also, in an extreme case, a thick sheet such as glossy paper or a postcard can be a printing target. .
A sheet having a large thickness has a high bending rigidity and therefore has a strong shape restoring force when bent. When a sheet having such mechanical characteristics is moved along the above-described sheet conveyance path having the reversing path, the sheet recurs at the reversing portion due to the shape restoring force. For this reason, when the thick sheet folded back toward the flat portion of the transport belt is moved, the leading end is likely to bend back, so that it is difficult to be attracted to the flat portion of the transport belt.
In particular, when the sheet moving toward the flat portion of the conveyor belt is reoriented by the shape restoring force in the same direction as the roller on which the conveyor belt is wound when the direction is changed, the leading end of the sheet moves from the peripheral surface. Leave. Therefore, it is conceivable to prepare a counter roller or the like that presses against the peripheral surface. However, since the portion to be pressed is only the position facing the counter roller, the counter roller cannot be moved completely following the roller peripheral surface.
[0009]
In such a situation, the sheet cannot be guided to the flat portion of the transport belt, or even follow the flat portion. As a result, the facing distance between the ink head and the sheet is not constant, and the image quality deteriorates. Will not escape.
[0010]
SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described conventional sheet conveyance device, particularly in consideration of the problem of conveying a stiff sheet when the conveyance path has a direction change, so that even a thick sheet can be conveyed to a conveyance belt. It is an object of the present invention to provide a sheet conveying apparatus and an ink jet recording apparatus having a configuration capable of improving the adhesiveness of the sheet and maintaining a constant distance between the sheet and the printing unit.
[0011]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a sheet transporting apparatus having a configuration in which a part of a transport path fed from a paper feeding unit is changed in direction, and a guide for directing the sheet in the converted direction to the direction changing position. It is characterized by having a part.
[0012]
According to a second aspect of the present invention, in addition to the first aspect of the present invention, when the guide portion uses a transport belt for electrostatically adsorbing the sheet, the guide portion is provided outside a roller around which the transport belt is wound. It is characterized by having a guide surface provided around the periphery and having a curved surface having an angle to direct the leading end of the sheet toward a flat portion formed on the transport belt.
[0013]
According to a third aspect of the present invention, there is provided a method of using the sheet conveying apparatus according to the first or second aspect in an ink jet recording apparatus.
[0014]
According to a fourth aspect of the present invention, in addition to the third aspect, the flat portion of the transport belt is formed by moving the transport belt on a guide member arranged at a position facing the ink head. It is characterized by being done.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram illustrating an ink jet recording apparatus to which a sheet conveying apparatus according to an embodiment of the present invention is applied. The ink jet recording apparatus 100 shown in FIG. 1 includes, in addition to plain paper generally used for copying and the like, an OHP sheet. Any of cardboard, cardboard, postcards, and other thick paper and envelopes can be used as a sheet-shaped recording medium.
[0016]
In FIG. 1, the ink jet recording apparatus 100 has a paper feed unit SP and a paper discharge unit EP installed vertically in a housing, and a sheet S fed from the paper feed unit SP is indicated by a dashed line in FIG. As described above, a configuration is adopted in which the direction is changed in the vertical direction, reversed, and then fed to the print processing unit PP, and after the print processing, the paper is discharged toward the paper discharge unit EP in the moving direction. .
In the sheet feeding unit SP, the sheet feeding tray 10, the sheet feeding roller 11, the separation pad 12 that comes into contact with the sheet feeding roller 11 to feed one sheet of the sheet S, and the conveyance direction of the sheet fed from the sheet feeding tray 10 are set to approximately 90 degrees. A conversion guide member 13 for converting the sheet S is provided, and in the conveyance path of the sheet S whose direction has been further changed, the sheet S is further turned 90 degrees toward the print processing unit PP and is fed out of the paper feed tray 10. A reversing conversion guide member 14 for reversing the sheet S is provided.
[0017]
The print processing unit PP that performs print processing on the sheet S fed from the paper supply unit SP includes an ink head 15 having ink discharge nozzles, and mounts the ink head 15 at right angles to the paper surface during the print processing. And a carriage 16 that reciprocates in various directions.
[0018]
The print processing unit PP is provided with a structure for printing the sheet S facing the ink head 14, and the structure is provided with a transport belt 17.
The transport belt 17 is an endless belt composed of a charging member having at least an insulating layer on the surface, and is wound around a driving roller 18 and a tension roller 19 disposed on both sides of an image forming area where the ink head 15 is located. ing.
The surface of the conveyor belt 17 facing the ink head 15 is arranged on the back side and moved on a guide member 20 having a flat surface to be stretched in a state where a flat portion is formed. The sheet S moving to the image forming area is statically charged by the charging roller 21 which is opposed to and abuts on the upstream side in the moving direction of the sheet S from the sheet feeding unit SP in the rotation direction (the arrow direction in the drawing). It can be transported while being electroadsorbed.
[0019]
In one of the directions in which the sheet S moves across the flat portion of the transport belt 17 facing the ink head 15, a discharge roller 22 for discharging the sheet S after the printing process toward the discharge portion EP is provided. On the other side of the direction in which the sheet moves across the sheet feeding roller 23, a conveying roller 23 that feeds the sheet toward the image forming processing unit is disposed.
[0020]
FIG. 2 is a diagram illustrating a configuration of a position where the sheet S whose direction has been changed with respect to the transport belt 17 is introduced. In FIG. A direction changing guide member 24 for changing the direction of the sheet S fed from the paper section SP in a horizontal direction parallel to the flat portion of the transport belt 17 is provided.
The direction conversion guide member 24 is provided separately from the counter roller 25 provided facing the drive roller 18 of the transport belt 17 and the conversion transport guide member 14 which faces the counter roller 25 and converts the transport path of the sheet S by 90 degrees. The position of the sheet S whose direction has been changed by the conversion conveyance guide member 14 is easily separated by the curvature of the drive roller 8.
In this case, the position where the curvature is easily separated means that the sheet which is pressed against the peripheral surface of the driving roller 18 by the counter roller 25 and is shaped to follow the peripheral surface of the driving roller 18 has a shape restoring force due to its own bending rigidity. In the configuration shown in FIG. 2, it is located behind the position where the drive roller 18 and the conveyance roller 23 face each other in the sheet moving direction.
[0021]
The direction conversion guide member 24 has an angle for directing the sheet in the direction in which the sheet is converted, in this case, from the vertical direction to the horizontal direction, at a position where the leading end of the sheet warps from the drive roller 18 side and separates from the drive roller 18 side. (A guide angle 24 in FIG. 2) is provided with a guide surface 24A made of a curved surface or an inclined surface.
In the case of a curved surface, it means that a surface having an angle for directing the sheet is partially present.
In the case of a curved surface, as shown by a two-dot chain line in FIG. 2, the leading end of the sheet away from the drive roller 18 moves to a surface of an angle to be directed while being curved along the curved surface, In the case of an inclined surface, although not shown, when the leading end abuts, the sheet is bent as it is and is directed toward the flat portion of the transport belt 17. The curved surface is effective for a sheet which is relatively thick and is hard to bend, and the inclined surface is effective for a thin sheet which is easily bent by abutting.
[0022]
Since the present embodiment is configured as described above, the sheet S fed from the sheet feeding unit SP is changed in the vertical direction during the conveyance, and is again changed from the vertical direction to the horizontal direction, that is, the flat portion of the conveyance belt 17. The direction is changed in the direction parallel to.
At the position where the direction is changed toward the flat portion of the conveyor belt 17, when the front end warps from the driving roller 18 of the conveyor belt 17, the front end enters the guide surface 24 </ b> A of the direction conversion guide portion 24, and follows the surface. 2 and is directed toward the flat portion of the transport belt 17 as shown by a two-dot chain line in FIG.
[0023]
In particular, when the leading end of the sheet S enters the guide surface 24A of the direction changing guide portion 24, the subsequent portion can also continuously pass through the guide surface 24A. The state of being directed toward the flat portion 17 is maintained. As a result, the sheet can be brought into close contact with the transport belt 17 in the flat portion due to the electrostatic attraction by the transport belt 17, and the flat portion of the transport belt 17 is opposed to the ink head 15 by the guide member 20 located on the back side thereof. The interval of the sheet S facing the ink head 15 is also fixed in accordance with the regulation. As a result, the ejection points of the ink from the ink head 15 do not become non-uniform, and deterioration of the image quality is prevented.
[0024]
【The invention's effect】
According to the first and second aspects of the present invention, a guide portion for directing the sheet in the converted direction is provided at the direction conversion position. In the second aspect of the present invention, the guide portion wraps around the plate cylinder belt. It has a curved surface or an inclined surface that is disposed around the outer periphery of the roller and directs the sheet toward the flat portion of the conveyor belt, so that the sheet is moved in the process of moving the sheet along the surface. It is possible to maintain a state in which the transfer belt is directed to the flat portion. Accordingly, the state in which the leading end of the sheet and the subsequent surface are directed toward the flat portion by the guide portion is maintained, so that the sheet is easily electrostatically attracted by the transport belt, and the flatness of the transport belt is imitated. it can.
[0025]
According to the third and fourth aspects of the present invention, since the flat portion of the transport belt is formed by moving the transport belt on the guide member disposed at a position facing the ink head, the flat portion is directed toward the flat portion. The moved sheet can move following the flatness of the transport belt. Accordingly, when the guide member has a prescribed distance from the ink head, the sheet following the flat portion of the transport belt also has a prescribed distance from the ink head. And the like can be eliminated, and deterioration of image quality can be prevented.
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating an example of an image forming apparatus to which a sheet conveying device according to an embodiment of the present disclosure is applied.
FIG. 2 is a schematic diagram for explaining a main configuration of a sheet conveying apparatus according to an embodiment of the present invention.
[Explanation of symbols]
SP paper feed unit PP print processing unit EP paper discharge unit 100 inkjet recording device 13 conversion guide member 14 inversion conversion guide member 15 ink head 17 transport belt 18 drive roller 19 tension roller 22 discharge roller 23 transport roller 24 direction conversion guide member 24A Guide surface 25 Counter roller S sheet

Claims (4)

In a sheet conveying apparatus having a configuration in which a part of a conveying path fed from a sheet feeding unit is changed in direction,
A sheet conveying device, comprising: a guide unit for directing the sheet in the changed direction at the direction change position. The sheet conveying device according to claim 1,
The guide section, when using a transport belt that electrostatically attracts the sheet, is disposed around the roller around which the transport belt is wound, and faces the flat portion formed on the transport belt. A sheet conveying device having a guide surface having a curved surface or an inclined surface having an angle for directing a leading end of a sheet. An ink jet recording apparatus using the sheet conveying apparatus according to claim 1. The inkjet recording apparatus according to claim 3,
The ink jet recording apparatus according to claim 1, wherein the flat portion of the transport belt is formed by moving the transport belt on a guide member disposed at a position facing the ink head.

Images