JP2010018413A - Paper feeder and image forming device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paper feeder capable of satisfying stable paper feeding performance by maintaining a nearly constant angle in approach to a friction pad even if the stacking quantity of paper sheets is changed. <P>SOLUTION: A lever 10 is provided under a bottom plate 3 so as to be always brought into contact with the bottom plate 3 by pressurization of a compression spring 16, which is provided on a cassette body 6, independently of position of the bottom plate 3 to be fluctuated in position thereof in the vertical direction. A lever 19 is fitted to freely to turn around a support point 17 of the cassette body 6. An end of the lever 19 on an opposite side relative to the support point 17 on a side abutting on the bottom plate 3 is fitted freely to turn with a holder 13 around the support point 20. The lever 19, the holder 13 and a friction pad 10 are turned, linking with vertical movement of the bottom plate 3, to properly position the turning support point of the lever 19 and the holder 13 and to nearly coincide an angle in approach to the friction pad 10 independently of height of the paper sheets on the bottom plate 3. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a paper feeding device used in an image forming apparatus such as a copying machine, a facsimile machine, a laser printer, and a multifunction machine of these, and more specifically, separates and feeds sheets stacked in a paper feeding tray one by one. The present invention relates to a paper feeding device using a friction separating paper feeding method for paper, and an image forming apparatus using the same.

  In recent years, the number of sheets used in copiers, printers, and the like is increasing, and there is an increasing demand for a larger number of sheets to be stored in a sheet feeding device used to supply sheets.

  On the other hand, the papers to be fed in these paper feeders include a wide variety of paper such as envelopes and postcards. In order to cope with this, the papers are separated and conveyed one by one. In order to achieve this, a friction separation method, that is, a so-called friction pad method has been widely adopted.

  FIG. 1 is a conceptual sectional view showing a paper feeding device of a conventional image forming apparatus such as a laser printer. In the figure, 1 is a paper feed roller, 2 is a paper feed cassette, 3 is a bottom plate of the paper feed cassette, 4 is a conveyance roller, 5 is paper, 6 is an image forming unit, 7 is a fixing unit, 8 is a paper discharge unit, It is a paper discharge tray. The paper feed cassette 2 is provided on the right side of the figure so that it can be pulled out.

  In this paper feeder, in order to separate the paper 5, a friction pad 10 is provided below the paper feed roller 1, and the paper 5 in the paper cassette 2 is fed by a so-called friction pad separation method. It has become.

  In this friction pad type paper feeding device, when the papers 5 to be fed are stacked and the bottom plate 3 rotating in the vertical direction with respect to the transport direction is used on the downstream side in the transport direction, In order to deal with paper feeding and conveyance, the paper entry angle with respect to the friction pad 10 changes when a small number of sheets 5 are set (FIG. 2) and when a large number of sheets are set (FIG. 3). That is, as shown in the drawing, the angles θ and θ ′ formed by the tangential direction between the upper surface of the stacked paper 5 and the upper surface of the paper feed roller 1 and the friction pad 10, that is, the paper feed direction, are determined by the number of sheets 5. Since the bottom plate 3 rotates and rises as the number decreases, the number of fed sheets increases and increases as the number of sheets remaining on the bottom plate 3 decreases.

  The entrance angles θ and θ ′ of the paper 5 are largely caused by the conveyance performance of the paper 5, and when the entrance angle of the paper 5 with respect to the friction pad 10 is large (FIG. 3), the fed paper 5 is the friction pad. Since the transport load at the time of contact with the sheet 10 is large, the effect of separating the sheet 5 when a plurality of sheets 5 are fed is great. However, if the entry angle is too large, the fed sheet becomes a friction pad. There is a case where the paper 5 is buckled by the collided load, causing a failure that the paper is not conveyed (FIG. 4).

  Therefore, in order to satisfy the stable paper feeding performance regardless of the height of the sheet 5 on the bottom plate 3, it is desirable to make the change in the angle of entry of the sheet 5 into the friction pad as small as possible.

  As a means for solving this problem, in Patent Document 1, the sheet feeding bottom plate is divided into at least two pieces, and the bottom plate portion 3a on the leading end side is moved up and down substantially parallel to the sheet feeding roller to thereby adjust the paper entrance angle. An invention is disclosed which seeks to remain substantially constant.

JP-A-5-270667

  However, in the above-described conventional apparatus, when the rigidity of the sheets 5 stacked on the bottom plate 3 is strong, the sheets 5 do not come into contact with the bottom plate 3 at the front side of the sheet feeding side of the bottom plate 3, and the sheets of paper to the friction pad are not contacted. In some cases, the approach angle was not as intended (FIG. 5).

  Therefore, the present invention provides a paper feeding device that can maintain a substantially constant angle of approach to the friction pad even if the paper stacking amount changes, and that can satisfy a stable paper feeding performance, and an image forming apparatus using the same. The purpose is to provide.

  A sheet feeding device according to a first aspect of the present invention includes a bottom plate whose angle varies depending on a stacking height of a plurality of sheets stacked in a sheet feeding cassette so as to be rotatable in the vertical direction, and is stacked on the bottom plate. A sheet feed roller that conveys the sheets in the abutting order, and an uppermost surface that is in contact with the outer peripheral surface of the sheet feed roller on the downstream side in the sheet conveyance direction, and a plurality of sheets are to be conveyed from the sheet feed roller A friction separating member for separating one sheet of paper from other sheets, the friction separating member having a variable angle with respect to a conveying direction of the sheet conveyed from the sheet feeding roller, and stacking An angle variable means is provided for changing an angle of the friction separating member with respect to the sheet conveyance direction in conjunction with the bottom plate, which varies according to the sheet stacking height.

  According to a second aspect of the present invention, in the paper feeding device of the first aspect, a link mechanism is interposed as the angle changing means.

  According to a third aspect of the present invention, in the paper feeding device according to the second aspect, the link mechanism includes a lever that is arranged at a lower portion of the bottom plate and presses and urges the bottom plate upward by pressing a compression spring, The lever is always in contact with the bottom plate regardless of the vertical position fluctuation of the bottom plate.

  According to a fourth aspect of the present invention, in the paper feeding device of the third aspect, the lever is attached so as to be pivotable in a vertical movement direction of the bottom plate around a fulcrum provided in the paper feeding cassette. The opposite end to the fulcrum on the side in contact with the bottom plate is rotatably attached to the holder around the fulcrum.

  According to a fifth aspect of the present invention, there is provided the paper feeding device according to the fourth aspect, wherein the friction pad is attached to the shaft of the paper feeding roller so as to be rotatable along the outer circumferential direction of the paper feeding roller. The friction pad is slidably attached in the center direction of the paper feed roller, and the friction pad is pressed against the paper feed roller by the compression spring in the holder.

  According to a sixth aspect of the present invention, an image forming apparatus according to any one of the first to fourth aspects is used.

  In the present invention, since the angle of the friction pad changes in conjunction with the angle of the bottom plate, the angle of entry into the friction pad can be kept substantially constant even when the amount of paper loaded changes, and stable paper feeding performance can be achieved. realizable.

  The best mode for carrying out the present invention will be described below with reference to the embodiments shown in the drawings. In the following description, the same reference numerals are given to portions common to the conventional example.

  6 and 7 are side cross-sectional views showing the main parts of the paper feeding device according to the present invention. The sheet feeding device 15 according to the present embodiment is arranged inside the main body of the box-shaped sheet feeding cassette 2 that is open at the top and can store the sheet 5 and is pivotable in the vertical direction around the fulcrum portion 17. The bottom plate 3 provided, the end fence 18 provided so as to be slidable in the direction along the feeding direction of the paper 5 and aligning the rear end portion in the feeding direction of the paper 5, are in contact with the outer peripheral surface of the paper feeding roller 1. A friction pad 10 and the like for separating and feeding the paper 5 together with the paper feed roller 1 are configured.

  The bottom plate 3 is rotated by a push-up type or pull-up type spring (not shown) in such a direction that the front end side of the paper 5 placed on the bottom plate 3 is brought into contact with the outer peripheral surface of the paper feed roller 1. It is urged upwards to do.

  The friction pad 10 is configured by attaching a cradle 11 as a base material to the lower side of the friction member 10a and the friction member 10a. The friction pad 10 is slidably attached in the central direction of the paper feed roller 1 with respect to a holder 13 that is rotatably attached to the shaft 12 of the paper feed roller 1 along the outer peripheral direction of the paper feed roller 1. The friction pad 10 is pressed against the paper feed roller 1 by a compression spring 14 in the holder 13.

  The lever 10 is always in contact with the bottom plate 3 at the bottom of the bottom plate 3 regardless of the position of the bottom plate 3 whose position changes in the vertical direction by the pressure of the compression spring 16 on the cassette body 6. The lever 19 is attached so as to be rotatable about the fulcrum part 17 of the cassette body 6, and the opposite end of the lever 19 on the side in contact with the bottom plate 3 is centered on the fulcrum 20. The holder 13 is pivotably attached.

  With the above configuration, the lever 19, the holder 13, and the friction pad 10 are rotated in conjunction with the vertical movement of the bottom plate 3, and further, the position of the rotation fulcrum of the lever 19 and the holder 13 is optimized. As a result, regardless of the height of the sheet on the bottom plate 3, the approach angles θ1 and θ2 to the friction pad 10 can be substantially matched.

  In other words, in the present invention, the angle of the friction pad changes in conjunction with the angle of the bottom plate, so that the angle of entry into the friction pad can be kept substantially constant even when the amount of loaded paper changes, and stable paper feeding performance is achieved. A paper feeding device to be realized can be provided, and a simple link mechanism is adopted, so that a relatively simple configuration is sufficient.

Conceptual sectional view showing a paper feeding device of a conventional image forming apparatus such as a laser printer Sectional view of the paper feeder when setting a small number of sheets Sectional view of the paper feeder when setting multiple sheets of paper Sectional drawing which shows the state which the paper buckled by the load which the fed paper collided with the friction pad Sectional view showing the case where the paper entrance angle to the friction pad is not as intended Side surface sectional view which shows the principal part of the paper feeder concerning this invention Side surface sectional view which shows the principal part of the paper feeder concerning this invention

Explanation of symbols

1: Paper feed roller 2: Paper feed cassette 3: Bottom plate of paper feed cassette 3a: Bottom plate portion on the front end side of the bottom plate 4: Transport roller 5: Paper 6: Image forming portion 7: Fixing portion 8: Paper discharge portion 9: Ejection Paper tray 10: Friction pad 10a: Friction member of friction pad 11: Receiving base to which the friction member is attached 12: Shaft of feed roller 13: Holder 14: Compression spring 15: Feeding device 16: Compression spring 17: Support point 18: End fence 19: Lever 20: Support point θ, θ ′: Paper entry angle

Claims (6)

A paper feed roller that includes a bottom plate whose angle varies depending on a stacking height of a plurality of sheets stacked in a paper feed cassette so as to be pivotable in the vertical direction, and that transports the sheets stacked on the bottom plate in the order of contact; The sheet on the uppermost side is separated from the other sheets when a plurality of sheets are to be conveyed from the sheet feeding roller in contact with the outer peripheral surface of the sheet feeding roller on the downstream side in the sheet conveying direction. In a paper feeding device having a friction separating member,
The friction separating member is variable in angle with respect to the conveying direction of the sheet conveyed from the paper feeding roller, and interlocks with the bottom plate that varies according to the stacking height of the loaded sheet, so that the sheet of the friction separating member A sheet feeding device comprising angle varying means for changing an angle with respect to a conveyance direction. 2. A paper feeding apparatus according to claim 1, wherein a link mechanism is interposed as said angle changing means. 3. The sheet feeding device according to claim 2, wherein the link mechanism includes a lever that is disposed below the bottom plate and urges the bottom plate upward by pressing a compression spring. A paper feeding device that is always in contact with the bottom plate regardless of a change in direction and position. 4. The paper feeding device according to claim 3, wherein the lever is attached so as to be rotatable in the vertical movement direction of the bottom plate around a fulcrum provided in the paper feeding cassette, and is in contact with the bottom plate of the lever. The sheet feeding device is characterized in that an end opposite to the fulcrum is rotatably attached to the holder around the fulcrum. 5. The sheet feeding device according to claim 4, wherein the friction pad slides in a center direction of the sheet feeding roller with respect to a holder that is rotatably attached to an axis of the sheet feeding roller along an outer circumferential direction of the sheet feeding roller. The sheet feeding device is freely attached, and the friction pad is pressed against the sheet feeding roller by the compression spring in the holder. An image forming apparatus using the sheet feeding device according to claim 1.