JP3224321B2 - Paper feeder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feeder mounted on an image forming apparatus such as a copying machine, a facsimile, a printer, etc., for feeding a document, recording paper, etc., one by one.

[0002]

2. Description of the Related Art As a sheet feeding device used in an image forming apparatus, a document, a recording sheet, and the like (hereinafter, collectively referred to as sheets) stacked on a sheet feeding table are separated into one sheet from the lowest sheet. A sheet feeding device of a feeding type is well known.

In the paper feeder of the downward feeding type, a certain amount of frictional force must be applied between the paper and the paper feed roller in order to reliably feed the paper. for that reason,
Conventionally, a paper feed table is inclined to apply a forward force such that the leading end of the paper bites into the contact portion between the paper feed roller and the separating means. However, inclining the sheet feeding table causes an increase in the height of the apparatus. If the paper feed table is provided horizontally to prevent this, a sufficient frictional force will not act because the paper advance force cannot be obtained.

Therefore, an auxiliary roller (pickup roller) is provided in front of the paper feed roller (feed roller) (in front of the paper transport direction) and a pressing member for pressing the paper from above is provided, and the paper is held between the pickup roller and the pressing member. A paper feeder has been proposed in which a forward force is applied to the paper to cause the leading end of the paper to bite into a contact portion between the paper feed roller and the separating means.

An example of such a paper feeder will be described with reference to the drawings.

In the paper feeder shown in FIG. 2, a part of the peripheral surface protrudes from the document table 1 and a feed roller 2 and a pickup roller 3 is rotatably provided upstream of the feed roller 2 in the paper transport direction. The separation member 4 is provided with its lower end pressed against the feed roller 2. Above the pickup roller 3, a pressure plate 5 for pressing the original is provided.
The shaft 6 is rotatably supported.

The document P is placed on the document table 1 such that the leading end of the document P contacts the separation member 4. When document feeding is instructed, the feed roller 2 and the pickup roller 3 rotate to apply a forward force to the document P. The manuscript is feed roller 2
And the separation member 4 separates the lowermost document into one sheet and sends it out in the direction of arrow S.

When the leading end of the pressure plate 5 extends as close to the separating member 4 as possible, the original can be pressed effectively, and the leading end of the original can be securely contacted between the feed roller 2 and the separating member 4. Can be led to.

However, usually, the separating member 4 is installed inclined backward, and the pressing plate 5 rotates about the shaft 6, so that when the number of documents P is large, the leading end of the pressing plate 5 is Contact with Therefore, it is impossible to bring the leading end of the pressure plate 5 closer to the separation member 4 than a predetermined position or more from the relationship with the number of documents that can be placed on the document table 1 at one time. In particular, when the pressing plate 5 is made of a thick sheet metal or a mold, the distance between the tip and the separation member 4 must be increased by the thickness. The same applies to a case where the separation member 4 is not a separation pad or a blade as shown in the figure, but a separation roller, and the pressure plate 5 must be separated so that the leading end does not contact the separation roller or the feed roller. However, the leading edge of the document cannot be pressed.

[0010]

Therefore, when the number of originals P is large to some extent, the original located below is pressed by the original above, and the upward curl and the jumping up of the leading end are small, but as shown in FIG. As described above, when the remaining number of originals is as small as one or two, the leading end of the original P is easily curled because there is no paper to be pressed from above, and when the leading end of the original is curled as shown by a dashed line in FIG. There has been a problem that the leading edge of the document is not correctly guided to the contact portion between the feed roller 2 and the separation member 4, and the document is not fed or the leading edge is bent.

The present invention solves the above-described problem in a conventional paper feeder in which an auxiliary roller is provided in front of a paper feed roller and a pressing member that presses a sheet from above is provided. An object of the present invention is to provide a sheet feeding device that feeds a sheet and does not cause non-feeding of the sheet or bending of the leading end.

[0012]

SUMMARY OF THE INVENTION According to the present invention, there is provided a pickup roller which contacts a lowermost surface of a sheet stacked on a paper feed tray and calls a sheet, and a top surface of the stacked sheet. A paper feeding mechanism including a paper pressing member that abuts and presses a paper against the pickup roller, a feed roller that feeds the paper picked up by the pickup roller, and a separation unit that is pressed against the feed roller. In the paper apparatus, when one sheet of paper is sandwiched between the pickup roller and the pickup roller, the sheet pressure surface is substantially located on a tangent line connecting the pickup roller and the outer peripheral surface of the feed roller. And a thin elastic member is mounted on the paper pressing surface, and the leading end of the elastic member in the paper transport direction is the leading end of the paper pressing member. It is solved by being extended to the separating means to the vicinity pressing position between the feed rollers.

[0013]

The sheet pressing member is provided such that when one sheet is sandwiched between the pickup roller and the sheet, the sheet pressing surface is substantially located on a tangent line connecting the outer peripheral surfaces of the pickup roller and the feed roller. Have been. In addition, a thin elastic member is mounted on the sheet pressing surface so that its leading end in the sheet conveying direction extends from the leading end of the sheet pressing member to the vicinity of the pressure contact position between the separating means and the feed roller. Therefore, when the number of sheets loaded on the sheet feeding table and pressed against the pickup roller by the sheet pressing member is one or a few,
The leading end of the sheet is curled by the leading end of the elastic member (the portion extending from the sheet pressing member), and is reliably guided to the pressure contact position between the separating means and the feed roller.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. Parts similar to those of the conventional sheet feeder described with reference to FIGS. 2 and 3 are denoted by the same reference numerals and described.

FIG. 1 is a side view showing the configuration of a document feeding apparatus according to one embodiment of the present invention. In this figure, a part of the peripheral surface protrudes from the document table 1, and a feed roller 2 and a pickup roller 3 are provided rotatably downstream of the feed roller 2 in the sheet conveyance direction. The separation member 4 is provided with its lower end pressed against the feed roller 2. Above the pickup roller 3, a pressure plate 5 for pressing a document is rotatably supported by a shaft 6. When there is only one sheet of paper between the pressure plate 5 and the pickup roller 3, the lower surface of the pressure plate 5 is located on a tangent line connecting the pickup roller 3 and the feed roller 2. Also,
On the lower surface of the pressure plate 5, for example, a PET film known under the trade name of Mylar, or a thin pressing auxiliary member 7 formed of an elastic member such as a plate spring or rubber coated so as to have an appropriate sliding degree is provided. It is stuck. The leading end of the pressing auxiliary member 7 in the paper transport direction (the direction of arrow S) is extended from the leading end of the pressing plate 5 toward the separating member 4, and when the pressing plate 5 is located at the lowest position, the leading end of the pressing auxiliary member 7 is The length is located immediately before the separating member 4.

A document (not shown) is set on the document table 1, and
When the pressing plate 5 rotates clockwise as shown by the two-dot chain line in the figure and moves upward, the tip of the pressing auxiliary member 7 contacts the separating member 4, but the pressing auxiliary member 7 has elasticity. Therefore, the leading end thereof is deformed following the separating member 4 and does not hinder the setting and feeding of the original.

As the document is fed and the number of remaining sheets decreases, the pressing plate 5 rotates counterclockwise in the figure and descends downward. Then, when the number of remaining documents becomes as small as one or two, the leading end of the pressing auxiliary member 7 presses the leading end of the document P as shown by a solid line in the drawing, thereby preventing the document from curling upward. Accordingly, the leading end of the document P is reliably guided to the contact portion between the feed roller 2 and the separating member 4, so that the document is reliably fed and the leading end of the document can be prevented from being bent.

The present invention is not limited to this embodiment. For example, the present invention is applicable not only to a separating blade as a separating means but also to a sheet feeding apparatus using a separating pad or a separating roller or a sheet feeding apparatus of an FRR system. It is possible to apply.

[0019]

As described above, according to the sheet feeding device of the present invention, when the number of sheets stacked on the sheet feeding table is small, or even when the number of sheets is reduced, the leading end of the sheet is pressed by the pressing member 7. To prevent the paper from curling or jumping up, and to reliably guide the paper to the press-contact portion between the separation means and the paper feed roller. The transfer performance can be exhibited.

[Brief description of the drawings]

FIG. 1 is a side view showing a schematic configuration of an embodiment of a sheet feeding device of the present invention.

FIG. 2 is a side view illustrating an example of a conventional sheet feeding device.

FIG. 3 is a side view illustrating a state where the number of remaining sheets is small in the sheet feeding device illustrated in FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Original table 2 Feed roller 3 Pickup roller 4 Separation member 5 Pressure plate 7 Press assistance member (elastic member)

Continuation of the front page (56) References JP-A-4-3727 (JP, A) JP-A-59-149241 (JP, A) JP-A-6-115718 (JP, A) Jpn. , U) Japanese Utility Model 1984-165840 (JP, U) Japanese Utility Model Application Hei 3-53935 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B65H 1/06 B65H 3/06

Claims (1)

(57) [Claims] A pickup roller for abutting against the lowermost surface of the paper stacked on the paper feeding table to call out the paper; and a paper pressure for abutting against the uppermost surface of the stacked paper and pressing the paper against the pickup roller. A sheet feeder having a member, a feed roller for feeding the sheet picked up by the pickup roller, and a separation unit pressed against the feed roller, wherein the sheet pressing member includes the pickup When one sheet is sandwiched between the roller and the roller, the sheet pressing surface is provided so as to be substantially located on a tangent connecting the outer peripheral surface of the pickup roller and the outer periphery of the feed roller. An elastic member is mounted, and the leading end of the elastic member in the sheet conveying direction is pressed against the separating means and the feed roller from the leading end of the sheet pressing member. Sheet feeding apparatus characterized in that it extends to 置近 near.