JP2009179451A - Paper feeding device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a friction separation type paper feeding device surely attaining separation and conveyance without causing double feeding and non-feeding even if paper sheets rush into it in a batch when a wide variety of papers are expected to be fed. <P>SOLUTION: The paper feeding device includes a feed member sending paper sheets, a frictional separation member separating overlapped papers one by one, a conveyance member contacting with the frictional separation member and conveying the papers downstream, and a support member holding the frictional member and retractably press-contacting the frictional separation member against the conveyance member, wherein the support member has an inclined portion on a paper conveyance upstream side of the frictional separation member, to which the front end of the fed paper bumps. A paper guide is arranged between the feed member and the inclined portion. The paper guide does not contact with the feed member and the conveyance member, is fixed independently from a paper loading plate and the support member and has an incline having a function of giving a conveyance load to papers and pre-arranging them by allowing front ends of the papers fed by the feed member to bump it. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a paper feeding device for supplying a recording medium (hereinafter referred to as paper) to the image forming means side, more specifically, a friction pad type paper feeding device, and a printer, a copier equipped with the paper feeding device, The present invention relates to an image forming apparatus such as a fax machine.

  2. Description of the Related Art Conventionally, in an image forming apparatus, a friction pad separation type sheet feeding device is known as a mechanism for separating and feeding one sheet at a time from recording sheets and documents in a stacked state. In a typical configuration of a friction pad separation type paper feeding device, a rotatable paper stacking plate arranged so as to bias the uppermost one of the stacked paper to the pickup roller / paper feed roller by a pressing means such as a spring. And a friction member support member that urges a friction pad (friction member) to the paper feed roller by pressing means such as a spring, and the sheet fed from the paper stacking plate by the paper feed roller is fed by the friction member. Separate them one by one.

  In recent years, as the image forming apparatus is reduced in size and space, the diameter of the roller is reduced, and the functions are divided by using the roller in each of the paper feeding unit and the separation unit (for example, Patent Document 1 and Patent Document 2).

  In those disclosed in these documents, the separation guide that is in pressure contact with the conveyance roller of the separation unit is conveyed to the separation guide side by the roller of the paper supply unit using the slope provided on the upstream side in the paper feeding direction. By applying a transport load to the leading edge of the paper bundle and forming a small step in the paper bundle following the slope, it is pre-wounded to make it easy to separate, and the separation guide is elastically supported. Paper is separated by a friction member (bank separation method). In addition, there is a separation pad method in which a friction member is pressed against a roller to separate paper.

  However, in such a paper feed mechanism, due to burrs during paper cutting, friction between papers, or when paper is loaded on a paper feed tray that is slanted to fall by its own weight, due to the weight of the paper itself, etc. A plurality of sheets may be bundled into a separation unit. In such a case, a strong stiffness occurs due to the bundle of sheets, and the separation guide hits a slope or a high friction member provided on the upstream side of the separation guide and pushes the separation guide downward against the elastic force. There is a problem in that the necessary pressure contact force against the conveying roller is weakened, separation is impossible, and double feeding occurs. Also, when feeding stiff paper such as thick paper alone, if it is bundled together and rushes into the separation part due to burrs at the time of cutting, the paper hits the slope of the separation guide and pushes the separation guide downward, and the transport roller There is a problem that the pressing force against the conveyance roller necessary for conveyance is lost between the sheet and the conveyance sheet, and the sheet is not fed.

Japanese Patent Laid-Open No. 2004-026493 JP 2004-244213 A

  In light of the problems of the conventionally known friction separation type paper feeding device, even when a wide variety of paper is supposed to be fed, even if the paper enters in a bundle, it does not cause double feed or non-feed. It is an object of the present invention to realize separation and transport.

  In accordance with the present invention, the above-described problems include a feeding member that feeds paper, a friction separating member that separates overlapping sheets one by one, a conveying member that contacts the friction separating member and conveys the paper downstream, and friction. A supporting member that holds the separating member and presses the friction separating member against the conveying member so as to be retractable. The supporting member is inclined so that a leading end of the fed paper abuts on the upstream side of the friction separating member. A sheet guide disposed between the feeding member and the inclined portion, the sheet guide does not contact the feeding member and the conveying member, and the sheet stacking plate and the support The problem is solved by having an inclined surface that is fixed independently from the member and has a function of imparting a transport load to the paper and pre-rolling the paper when the leading edge of the paper fed by the feeding member hits.

  It is preferable that the slope of the paper guide is configured so that the angle with respect to the end of the paper to be fed can be changed. It is more effective if it has a rotation fulcrum for changing the angle of the paper guide and a notch that is arranged at a position different from the rotation fulcrum and can change the engagement position with the main body frame. It is. It is also preferable that a friction member for applying a load to the fed paper is provided on at least the surface of the paper guide.

  According to the first aspect of the present invention, the paper guide is disposed between the feeding member and the inclined portion, and the paper guide does not contact the feeding member and the conveying member and is independent of the paper stacking plate and the support member. The front end of the sheet bundle fed by the feeding member is fixed, and has a slope having a function of pre-spinning by applying a transport load to the sheet by abutting the leading end of the sheet fed by the feeding member. The paper sheet is pre-copied by following the slope of the paper guide, and a small step is provided in the paper bundle to make it easy to separate. Thereafter, the paper bundle can be conveyed to the friction separation unit, and double feed and non-feed can be eliminated.

  If the slope of the paper guide is configured so that the angle with respect to the end of the paper being fed can be changed, it can be changed to the most suitable slope according to the type of paper and the angle of the tray bottom plate, and the front winding function is effective. Can be demonstrated. If the paper guide has a rotation fulcrum for changing the angle of the paper guide and a notch portion which is arranged at a position different from the rotation fulcrum and can change the engagement position with the main body frame, the front winding is performed. Can be improved with a simple configuration. Providing a friction member for applying a load to the paper to be fed is provided on at least the surface of the paper guide, which also helps to improve the front-winding function.

  FIG. 1 shows an outline of an image forming apparatus including a paper feeding device according to the present invention. The image forming apparatus shown in FIG. 1 is a laser printer, and an image formed by an electrophotographic method in an image forming unit composed of a photoreceptor, an exposure unit, a developing unit, and the like is primarily transferred to an intermediate transfer belt 20 and subjected to secondary transfer. Then, the toner image is transferred onto a sheet by a secondary transfer roller 22 in pressure contact with the intermediate transfer belt 20. The paper is fed from the cassette type paper feed tray 24 or the manual feed tray 26 by the paper feed mechanism, sent to the secondary transfer section through the registration roller pair 28, and after the image is transferred, the image is fixed by the fixing device 30. In the case of single-sided image formation, the paper is discharged onto a paper discharge tray 34 by a paper discharge roller 32. Further, in the case of double-sided image formation, a sheet on which an image is transferred and fixed on one side is re-fed through the sheet reversing means 36 and sent again through the registration roller pair 28 to the secondary transfer unit. Then, the image is transferred / fixed to the paper discharge tray 34.

  In this example, a paper feeding device according to the present invention will be described as a manual paper feeding device for feeding paper stacked on a manual tray. Needless to say, the paper feeding device according to the present invention can also be applied to the cassette type paper feeding tray 24 (in this example, the paper feeding tray 24 is not provisionally divided for paper feeding / separation). Is shown). First, the conventional paper feed conveyance will be described with reference to FIGS. 2 to 4, and then the structure of the paper feed conveyance according to the present invention will be described to facilitate understanding of the features of the present invention.

  The sheet feed tray bottom plate 2 can be rotated, and when feeding sheets stacked on the tray, the sheet feed tray 1 is attached to the sheet feed roller 1 as a feeding member by the pressing force of the sheet feed spring 3 as well as the sheet stacking amount. Be forced. Further, the separation pad 7 as the friction separation member on the separation guide 5 as the support member is urged to the conveyance roller 4 as the conveyance member by the pressing force of the separation spring 8, and is conveyed to the paper fed by the paper supply roller 1. A constant frictional force can be applied by the roller 4 and the separation pad 7.

  When a sheet is fed from the tray bottom plate 2 to the separation guide 5 by the conventional sheet feeding device, the leading edge of the sheet is first placed on the separation slope portion 6 on the separation guide 5 upstream in the sheet feeding direction as shown in FIG. At the end, separation before separation as shown in FIG. 4 is performed, and the paper is roughly separated. The paper that has been roughly separated by this front-rolling is sent to the separation pad 7 and separated one by one by the frictional force, and conveyed downstream in the paper feeding direction.

  When the relative change in the traveling direction angle (relative angle change) relative to the sheet feeding direction before the separation slope portion 6 or the separation pad 7 is forwarded is increased, the separation performance is improved, but the conveyance load is increased, and the sheet feeding roller 1 is increased. In addition, non-feed occurs in the transport roller 4 or the slip rate increases, resulting in poor transport performance. On the other hand, when the relative angle change is small, the conveyance performance is improved, but the separation property is deteriorated, and double feeding and follow-up are generated. It is desirable to increase the relative angle change for thin papers that are likely to cause double feed, and to reduce the relative angle change for thick papers that are likely to be non-feed. It is necessary to select the best value possible.

  When the paper to be fed is bundled by burrs or the like at the time of cutting and hits the separation slope portion 6 on the separation guide 5 at the tip, the separation guide 5 is pushed downward against the elastic force, and the pressing force required for separation Shortage causes double feed, separation pad 7 is separated from transport roller 4, non-feed occurs at transport roller 4, and insufficient pressing force from separation pad 7 causes insufficient transport force. On the other hand, because of the increasing conveyance resistance between the separation pad 7 and the sheet, the slip rate at the conveyance roller 4 and the paper feed roller 1 increases.

  In the present invention, first, as shown in FIG. 5, the separation guide 9 is fixedly disposed between the tray bottom plate 2 and the separation guide 5. Since the separation guide 9 is fixedly arranged between the tray bottom plate 2 and the separation guide 5, even if the paper that has entered the bundle hits the resin paper guide 9, it is not pushed down, and is the same as in the case of FIG. As shown in FIG. 6, a separation load is applied to the leading edge of the fed sheet bundle by applying a transport load so as to follow the inclined surface and providing a fine step in the bundle of sheets to facilitate separation. The paper can be supplied to the printer in a separable manner.

  At this time, the sheet guide 9 is improved in separation property and conveyance performance when the relative angle change with the tray bottom plate 2 is increased, as in the sheet feeding direction before the separation slope portion 6 and separation pad 7 are forwarded in the prior art. Deteriorate. On the other hand, when the relative angle change is small, the conveyance performance is improved, but the separation property is deteriorated. Therefore, the relative angle change of the paper guide 9 with respect to the tray bottom plate 2 can be mechanically changed according to the type of paper fed from the paper feed tray or according to the amount of paper stacked on the paper feed tray. You may make it comprise. As shown in FIG. 7, the paper guide 9 ′ is provided with the shaft 11, and as shown in FIG. 8, the shaft is fixed to the apparatus frame 12, and the paper guide 9 ′ and the end of the angle changing knob 13 are fixed. When the angle change knob 13 is moved up and down, the protrusions provided on the apparatus frame 12 and the angle change knob 13 are engaged with each other, so that the relative angle change between the tray bottom plate 2 and the paper guide 9 ′ can be changed. The relative angle change is increased for thin paper that is liable to generate a decrease, and the relative angle change is decreased for thick paper that is likely to be unfed. With such a mechanism, it is possible to set the relative angle change according to the paper type, and it is possible to deal with various papers.

  Further, as shown in FIG. 9, by allowing the friction member 14 to be attached to the upper surface of the paper guide 9 ″, it is possible to improve the efficiency of front-rolling with the paper guide 9 ″.

It is a schematic block diagram which shows the conventional image forming apparatus. It is a schematic block diagram which shows an example of the conventional general paper feeder. FIG. 3 is a diagram illustrating a state where paper is fed to a separation unit in the paper feeding device of FIG. 2. FIG. It is a schematic block diagram which shows an example of the paper feeder which concerns on this invention. FIG. 6 is a diagram illustrating a state where paper is fed to a separation unit in the paper feeding device of FIG. 5. It is a figure which shows the paper guide in another example of the paper feeder of this invention. It is a figure explaining the structure which makes a guide surface variable using the paper guide of FIG. It is a figure which shows the example which attaches a friction member to a variable paper guide.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Paper feed roller 2 Tray bottom plate 3 Paper feed spring 4 Carrying roller 5 Separation guide 6 Separation inclined part 7 Separation pad 8 Separation spring 9 Paper guide 11 Axis 12 Body frame 13 Angle change knob 14 Friction member

Claims (5)

A feeding member that feeds the paper, a friction separating member that separates the overlapping sheets one by one, a conveying member that contacts the friction separating member and conveys the paper downstream, and the friction separating member that holds the friction separating member and holds the friction separating member And a support member that presses against the transport member in a retreatable manner, and the support member has an inclined portion where the leading edge of the fed paper abuts on the upstream side of the paper separation of the friction separating member.
A paper guide is disposed between the feeding member and the inclined portion, and the paper guide is not in contact with the feeding member and the conveying member and is independently fixed from the paper stacking plate and the support member, A sheet feeding device having a slope having a function of imparting a transport load to a sheet and performing a front winding by abutting a leading end of the sheet fed by the feeding member.   The sheet feeding device according to claim 1, wherein the inclined surface of the sheet guide is configured to be capable of changing an angle with respect to a butt of the sheet to be fed.   A rotation fulcrum at the time of changing the angle of the paper guide, and a notch portion arranged at a position different from the rotation fulcrum and capable of changing an engagement position with the main body frame. The sheet feeding device according to 1 or 2.   The paper feeding device according to any one of claims 1 to 3, wherein a friction member for applying a load to the paper to be fed is provided on at least a surface of the paper guide.   An image forming apparatus comprising the paper feeding device according to claim 1.

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