JP2006298541A - Paper feeding device and image formation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paper feeding device capable of easily taking out a bundle of papers when a large number of papers are fed to a position near an upstream side of a separation part and capable of performing subsequent paper feeding action without trouble. <P>SOLUTION: In the paper feeding device, paper conveying passages 5, 6 provided between a paper tray 1 and the separation parts 7, 8 in its downstream side have a constitution that an entrance part 9 is spread. A paper height detection sensor 10 for detecting height of the bundle of papers entering the entrance part 9 is provided on a position near the entrance part. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a paper feeding device and an image forming apparatus equipped with the paper feeding device.

In an image forming apparatus provided with a sheet feeding device, the paper stored in the sheet feeding device is taken out by a sheet feeding roller and then separated one by one by a separation unit, and a registration roller positioned immediately before the image forming unit The paper is fed toward In a normal paper feeding operation, only the paper separated into one sheet by the separation unit is fed downstream in the paper transport path, and other paper following the fed paper is prepared for the next paper feeding operation. The paper tray is held at a normal paper feedable position.
However, in the paper feeding process, if other paper following the fed paper stays in the separation section and the leading end protrudes from the paper tray, the next paper feeding operation may be hindered. In addition, when the paper is ejected from the paper tray as described above, the paper is damaged when the paper tray is pulled out from the main body of the image forming apparatus.
For this reason, in Japanese Patent Laid-Open No. 5-58512, when a large number of sheets are fed, the skew of the sheets and the movement of the first sheet are detected by a sensor, and the sheet is fed. Techniques that stop operation have been proposed.
JP-A-5-58512

The above prior art is effective in the case where the paper is clumped because it is bound by a binding member such as a staple, but the paper is not bound by the binding member, but is caused by friction between the papers. Even if it has moved in a solid state, the paper feeding operation may be stopped. In other words, in this case, separation is normally performed and actual paper feeding should be possible, but the paper feeding operation is stopped. In other words, the detection configuration as described in JP-A-5-58512 may not accurately detect the state of a large number of sheets. In some cases, the sheet bundle cannot be taken out even if an attempt is made to pull out the sheet tray toward the front side of the image forming apparatus main body.
The present invention provides a sheet feeding device and an image forming apparatus that can easily take out a bundle of sheets and perform the next sheet feeding operation without hindrance when a large number of sheets are fed near the upstream side of the separation unit The purpose is to provide.

In order to achieve the above object, the invention described in claim 1 includes a paper tray that is detachably attached to the apparatus main body, a pickup roller that feeds paper from a bundle of paper accommodated in the paper tray, In the paper feeding device including a paper conveyance path that guides conveyance of the paper fed by the pickup roller and a separation unit that separates the paper conveyed through the paper conveyance path into one sheet, the paper conveyance path includes: The entrance portion has a configuration that can be expanded, and a sheet height detection sensor that detects the height of the sheet bundle that enters the entrance portion is provided in the vicinity of the entrance portion.
According to a second aspect of the present invention, in the paper feeding device according to the first aspect, any one of the upper guide plate and the lower guide plate constituting the paper transport path is rotated between the paper guide position and the paper take-out position. A main feature is a paper feeding device provided to be displaced.
According to a third aspect of the present invention, in the paper feeding device according to the second aspect, when the paper height detected by the paper height detection sensor exceeds a predetermined value, either the upper guide plate or the lower guide plate is The main feature of the sheet feeding device is that it is provided with a control means for performing control for displacing the entrance portion from the sheet guide position to the sheet take-out position.
According to a fourth aspect of the invention, an image forming apparatus including the paper feeding device according to the first aspect is the main feature.

  In the sheet feeding device of the present invention, the sheet conveyance path provided between the sheet tray and the separation section on the downstream side thereof has a configuration in which the entrance portion is widened, and the sheet bundle entering the entrance portion is near the entrance portion. A sheet height detection sensor for detecting the height of the sheet is provided. Specifically, either the upper guide plate or the lower guide plate constituting the sheet conveyance path is moved between the sheet guide position and the sheet take-out position. When the paper height detected by the paper height detection sensor exceeds a predetermined value, either the upper guide plate or the lower guide plate is moved from the paper guide position to the paper removal position. And a control means for controlling the expansion of the inlet portion, so that when a large number of sheets are fed in the vicinity of the upstream side of the separation section, the sheet bundle is easily taken out and the next feeding operation is performed. It can be executed without any problems.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram of a sheet feeding device according to an embodiment of the present invention. The paper feeding device includes a paper tray 1 and a paper feeding unit 2 arranged adjacent to the downstream side thereof. The sheet tray 1 has a rising plate 3 on which a sheet bundle P is stacked. A pickup roller 4 that can move up and down is disposed above the sheet bundle P. The paper tray 1 is configured to be drawable from the apparatus main body (image forming apparatus main body or paper feed apparatus main body). The drawing direction of the paper tray 1 is, for example, a direction orthogonal to the paper surface or a direction away from the paper feeding unit 2 (left side in the drawing).
The paper feed unit 2 has an upper guide plate 5 and a lower guide plate 6, and a paper feed roller 7 and a separation roller 8 are provided in pressure contact with each other in the middle of a paper conveyance path constituted by both. The separation part which isolate | separates one by one is comprised. A sheet height detection sensor 10 for detecting the height (thickness) of the sheet bundle is provided in the vicinity of the entrance portion 9 of the upper guide plate 5 and the lower guide plate 6 and on the side of the conveyance path. Is sent to the control means 11.
The lower guide plate 6 is configured such that the inlet side (upstream side) of the lower guide plate 6 is swung in the vertical direction between the paper guide position and the paper take-out position around the rotation shaft 12. A solenoid 13 and a spring 14 are attached to the lower guide plate 6 in the vicinity of the entrance. The solenoid 13 is connected to the control means 11, and when the solenoid 13 is turned on and the plunger 13a is retracted downward, the inlet portion side of the lower guide plate 6 resists the spring force (pushing force) of the spring 14. It is pulled downward (rotates counterclockwise) and retreats to the paper take-out position (opens the entrance 9) as shown in FIG. 3 to be described later. When the solenoid 13 is turned off and the plunger protrudes upward, the elastic force of the spring 14 pushes the lower guide plate 6 back to the paper guide position as shown in FIG. The inlet 9 may be opened and closed by swinging the upper guide plate 5 in the vertical direction.

FIG. 2 is a diagram illustrating a sheet feeding state in the sheet feeding device according to the embodiment of the present invention. FIG. 3 is a diagram illustrating a state in which the lower guide plate is in the sheet takeout position in the sheet feeding device according to the embodiment of the present invention. FIG. 4 is a diagram illustrating a state in which the lower guide plate has returned from the paper take-out position to the paper guide position in the paper feeding device according to the embodiment of the present invention.
When the paper is normally fed, even if a plurality of sheets (small number) are fed into the paper transport path in a state of being overlapped, they are separated one by one by the separation unit including the paper feeding roller 7 and the separation roller 8. Then, the paper is fed downstream (see FIG. 2).
If the number of sheets fed from the inlet 9 to the sheet conveyance path formed by the upper guide plate 5 and the lower guide plate 6 increases, the separation unit may cause a paper jam. When the sheet height to be exceeded exceeds a predetermined value, the control means 11 turns on the solenoid 13 to retract the lower guide plate 6 to the sheet take-out position (see FIG. 3).
In this state, since the inlet 9 is widened, the sheet bundle P does not hinder the sheet tray pulling out, and the sheet tray 1 can be easily pulled out and the sheets can be accommodated again. At this time, if a warning prompting the user to pull out the paper tray is displayed on a display panel (not shown), the convenience is further enhanced.
It should be noted that the paper tray drawing direction at this time can be assumed to be a direction orthogonal to the paper surface or a direction in which the paper tray is separated from the paper supply unit 2.
After removing the sheet bundle P, the control means 11 turns off the solenoid 13. Then, due to the elastic force of the spring 14, the lower guide plate 6 returns to the paper guide position as shown in FIG. In this state, the next paper feeding operation is executed.
The paper feeding device of the present invention can be applied not only to electrophotographic image forming apparatuses such as copying machines, printers, and facsimiles, but also to image forming apparatuses including ink jet printers and other printing apparatuses.

1 is a configuration diagram of a sheet feeding device according to an embodiment of the present invention. FIG. 3 is a diagram illustrating a paper feeding state in the paper feeding device according to the embodiment of the present invention. FIG. 6 is a diagram illustrating a state where a lower guide plate is in a paper take-out position in the paper feeding device according to the embodiment of the present invention. FIG. 6 is a diagram illustrating a state in which the lower guide plate is returned from the paper take-out position to the paper guide position in the paper feeding device according to the embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Paper tray, 5 Upper guide plate, 6 Lower guide plate, 7 Paper feed roller (separation part component), 8 Separation roller (separation part component), 9 Inlet part, 10 Paper height detection sensor, 11 Control means

Claims (4)

A paper tray that is detachably attached to the apparatus main body, a pickup roller that feeds paper from a bundle of paper stored in the paper tray, and a paper conveyance path that guides conveyance of the paper fed by the pickup roller And a separation unit that separates the sheet conveyed through the sheet conveyance path into one sheet,
The paper conveyance path has a configuration in which the entrance portion can be expanded, and a paper height detection sensor for detecting the height of a sheet bundle entering the entrance portion is provided in the vicinity of the entrance portion. Characteristic paper feeder.   2. The sheet feeding device according to claim 1, wherein either one of an upper guide plate and a lower guide plate constituting the sheet conveyance path is rotationally displaced between a sheet guide position and a sheet take-out position. A paper feeder characterized by.   3. The paper feeding device according to claim 2, wherein when the paper height detected by the paper height detection sensor exceeds a predetermined value, one of the upper guide plate and the lower guide plate is moved from the paper guide position. A sheet feeding device comprising control means for performing control to displace the sheet to a sheet take-out position and to widen the entrance. An image forming apparatus comprising the sheet feeding device according to claim 1.

Images