JP3776964B2 - Paper feeder - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a paper feeding device applied to an image forming apparatus such as a copying machine, a facsimile machine, a printer, and a printing machine. In particular, the bottom plate is accommodated in a bottomed box-shaped frame body having an open upper end. The present invention relates to a sheet feeding device of a type in which a front end portion is rotated upward and a sheet loaded on a bottom plate is pressed against an upper sheet feeding roller with an appropriate sheet feeding pressure.
[0002]
[Prior art]
FIG. 3 is a configuration diagram of a main part of a conventional paper feeding apparatus.
[0003]
The sheet feeding device includes a bottomed frame body (sheet feeding tray) 1 having an open top, a bottom plate 2 accommodated in the sheet feeding tray 1, and a bottom plate 2 near the tip of the sheet feeding tray 1. And a paper feed roller 8 fixedly disposed above.
[0004]
The bottom plate 2 is provided on the front end side of the bottom surface of the paper feed tray 1, and the paper P is stacked on the bottom surface of the paper feed tray 1 and the bottom plate 2 (the front end side of the paper P is stacked on the bottom plate 2). It is like that.
[0005]
The bottom plate 2 is bent upward at a right angle on both sides of the rear end portion to form an upright piece 3, and an engaging hole 4 is formed in the upright piece 3. An engagement pin 5 that engages with the engagement hole 4 is provided on the paper feed tray 1 side. The bottom of the bottom plate 2 is pivotable about a fulcrum formed by the engagement hole 4 and the engagement pin 5.
[0006]
A coil spring 6 is interposed between the bottom plate 2 and the bottom surface of the paper feed tray 1, and the bottom plate 2 is always urged upward by the elastic force of the coil spring 6. Accordingly, the sheet P is pressed against the sheet feeding roller 8 with an appropriate sheet feeding pressure.
[0007]
[Problems to be solved by the invention]
By the way, in order to stack the sheet bundles of the conventional sheet feeding tray 1 and cassette, in the bottom plate 2 which is a fulcrum (4, 5) whose one end is rotated, the fulcrum is the sheet feeding tray 1 and the cassette. By the engagement pin 5 provided on the side, the bottom plate 2 can only be rotated about the fulcrum.
When the maximum allowable number of sheets that can be stacked on the bottom plate 2 increases, the bottom plate 2 increases in the rising angle of the bottom plate 2 as the paper stacking amount approaches one sheet, and the leading end of the bottom plate 2 has a feeding direction ( It is located rearward with respect to the bottom plate ascending direction. When the bottom plate 2 is lifted, the leading end position of the stack of stacked sheets to be fed suffers from problems such as variation, double feed, non-feed, and jamming depending on the number of stacked sheets.
[0008]
Further, when the bottom plate 2 is raised, a sliding resistance force indicated by F in FIG. 3 acts between the stacked paper P and the bottom plate 2. A sliding resistance also acts between the bottom plate 2 and the bottom surface of the paper feed tray 1. If this sliding resistance becomes too large, the bottom plate 2 cannot be raised smoothly.
[0009]
As a solution to this, by increasing the fulcrum of the bottom plate 2, the leading edge of the bottom plate 2 is improved so that it protrudes forward in the paper feeding direction (bottom plate rising direction) as the paper stacking amount becomes one. Variations in the bottom plate tip depending on the number of sheets, especially troubles such as double feeding, non-feeding, jamming, etc., which are likely to occur when the bottom plate tip is located rearward at a small load, have been avoided.
[0010]
However, with the above-described solution alone, when the allowable loading number of sheets in the paper feed tray and cassette is increased to 500 sheets (large capacity), the weight on the bottom plate at the time of maximum size and full load becomes large. If the bottom plate is set so that the center of rotation (fulcrum) of the bottom plate is raised and protrudes forward like the bottom plate, the bottom plate cannot slide under the heavy paper stack. The sliding resistance with the paper bundle must be taken into account.
[0011]
However, in the case of corner nail feeding that smoothly moves up the bottom plate, when the bottom plate push-down movement needs to obtain the vertical movement of the bottom plate accurately by the half-moon shaped feeding roller, the sliding resistance between the bottom plate and the sheet bundle described above is required. If there is a large amount, the bottom plate cannot be raised smoothly, and at the same time, the bottom plate raising force becomes high, and the sheet feeding pressure to the half-moon-shaped sheet feeding roller cannot obtain an appropriate range.
[0014]
Since challenge of the present invention, changing the bottom plate turning center position by any number of stacked sheets, at full eliminates the sliding resistance between the bottom plate, the stacked paper sheets, at low loading, by the pushed out the bottom plate tip forward, It is an object of the present invention to provide a paper feeding device that can simultaneously solve the conventional problem and the problem of the allowable number of sheets being 500.
[0015]
[Means for Solving the Problems]
The above-described problems include a feeding roller, a bottom plate that can be contacted and separated with respect to the feeding roller that loads a plurality of sheets, and a top plate loaded on the bottom plate by applying pressure to the bottom plate. In the paper feeding device in the image forming apparatus having a bottom plate pressurizing mechanism that presses the paper against the paper feeding roller, the bottom plate is rotatably supported with one end portion as a fulcrum, and the fulcrum portion of the bottom plate is A slot having a center line that draws an arc centering on the end of the sheet loading surface on the fulcrum side of the bottom plate, and an engagement pin engaged with the slot, from full loading to any number of stacked sheets The sheet stacking surface end of the bottom plate is set as the center of the bottom plate so that the engagement pin moves through the slot, and the range from the arbitrary number of stacked sheets to the last sheet is located at the end of the slot. said engagement pin so as to increase the rotation center of the bottom plate, said bottom The center of rotation of is solved by first means for changing in two steps by an angle and sheet stacking amount of the bottom plate.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same location as a prior art example, and the overlapping description is abbreviate | omitted.
FIG. 1 is a configuration diagram of a main part of a sheet feeding device according to an embodiment, and FIGS. 2A and 2B are explanatory views showing the movement of a fulcrum when a bottom plate is rotated.
[0019]
As shown in these drawings, also in the present invention, a long hole 7 is formed in the standing piece 3 at the rear end of the bottom plate 2, and the long hole 7 is centered on the end A of the sheet stacking surface at the rear end of the bottom plate 2. The center line is set to have a drawn arc L1 or an approximate straight line L2. The engagement pin 5 shown in FIG. 3 is engaged with the arc-shaped elongated hole 7.
[0020]
Next, the operation of the embodiment will be described with reference to FIGS. 2 (a) and 2 (b).
2 (a) and 2 (b), the bottom plate 2a is fully loaded, 2b is an arbitrary number of sheets fed, and 2c is the last (final) paper. In FIG. 2A, from the state where the sheet is fully loaded on the bottom plate 2 (the bottom plate is at the position 2a) to the state where a predetermined (arbitrary stack) number of sheets is fed (the bottom plate is at the position 2b). 2B shows the first rotation process C1 and FIG. 2B shows the second rotation process C2 from the state of feeding a predetermined number of sheets to the last (final) paper (the bottom plate is at the position 2c). is there. In the bottom plate of FIG. 2A and FIG. 2B, the position of 2b is the same.
[0021]
First, in the first rotation process C1 shown in FIG. 2A, when the bottom plate is at the position 2a, the engagement pin 5 is at the left end of the long hole 7, and the point A is rotated as the bottom plate is raised. The long hole 7 rotates counterclockwise as the center, and the engagement pin 5 abuts on the right end of the long hole 7 so that the bottom plate is positioned at 2b. Thus, in the first rotation process C1, that is, in the range where the weight of the stacked paper on the bottom plate 2 is large, the bottom plate 2 is raised with the point A as the rotation center, and the sliding resistance F is reduced as much as possible. Let
[0022]
Further, in the second rotation process C2 shown in FIG. 2B, the bottom plate is raised with the contact point between the right end (tip) portion of the elongated hole 7 and the engagement pin 5 as the rotation center, and the tip B of the bottom plate Is being pushed out. This prevents problems such as double feeding, non-feeding, and jamming that occur when the tip of the conventional bottom plate 2 is positioned rearward with respect to the paper feeding direction.
[0023]
In such an embodiment, by applying pressure to the sheet feeding roller 8 and the sheet feeding roller 8 on which a plurality of sheets are stacked, the bottom plate 2 that can be contacted and separated, and the bottom plate 2 are applied. In the sheet feeding device in the image forming apparatus having the bottom plate pressurizing mechanism that presses the uppermost sheet loaded on the bottom plate 2 against the sheet feeding roller 8, the bottom plate 2 is rotatably supported with one end as a fulcrum. At the same time, since the fulcrum portion of the bottom plate 2 is the long hole 7, the bottom plate 2 freely moves in the direction of the long hole, and the sliding of the stacked paper P and the bottom plate 2 and the bottom plate 2 and the contact member when the bottom plate 2 is raised. The dynamic resistance can be suppressed to the minimum, the smooth rise of the bottom plate 2 can be obtained, and the paper can be fed without non-feeding and double feeding.
[0024]
Further, since the slot 7 in the fulcrum portion of the bottom plate 2 has a center line that draws an arc L1 centering on the end of the sheet stacking surface on the fulcrum portion side of the bottom plate 2, the bottom plate 2 rises when the stacked sheets P are fully loaded. The center of rotation is centered on the end A of the paper stacking surface on the bottom plate 2 fulcrum side, eliminating sliding resistance between the heavy stacked paper P and the bottom plate 2, allowing the bottom plate 2 to rise smoothly and accurately. Can move up and down, and can feed without unfeeding and double feeding.
[0025]
Further, when the bottom plate is raised from the full load to an arbitrary number of sheets, the slot 7 is used, the sheet stacking surface end A of the bottom plate 2 is set as the center of the bottom plate 2 ascending rotation, and from the arbitrary number of sheets to the last sheet. Since the end portion of the long hole 2 is divided into two stages with the bottom plate 2 as the center of ascending rotation, the long hole 2 is used from the time of full loading to the arbitrary stacking number, and the bottom plate paper stacking surface end A is Since the center of rotation of the bottom plate is the center, the sliding resistance between the paper P and the bottom plate 2 when fully loaded is eliminated, the vertical movement of the bottom plate 2 can be obtained accurately, and from the arbitrary number of stacked sheets to the last paper Since the end of the bottom plate 2 long hole 7 is the center of rotation of the bottom plate 2, the tip B of the bottom plate 2 in a small stacking state protrudes forward in the paper feeding direction, and the conventional bottom plate tip is moved backward. The problem of positioning can also be solved, and the capacity can be increased such as 500 sheets of paper trays and cassettes. It can respond.
[0026]
【The invention's effect】
According to the first aspect of the present invention, from the full load to the arbitrary number of stacked sheets, the bottom plate sheet stacking surface end is centered on the bottom plate ascending so that the engagement pin moves through the long hole, and the arbitrary number of stacked sheets is set. From the first sheet to the last sheet, the rotation center of the bottom plate changes in two steps depending on the angle of the bottom plate and the paper stacking amount so that the engaging pin located at the end of the long hole is used as the ascending rotation center of the bottom plate. Eliminates sliding resistance between the paper and the bottom plate when fully loaded, provides accurate vertical movement of the bottom plate, and the bottom plate long hole end is the center of bottom plate rotation from the arbitrary number of sheets to the last paper Thus, the bottom plate tip in the case of small stacking moves to the front with respect to the paper feeding direction, so that the problem of the conventional bottom plate tip located rearward can be solved, and the loading capacity of the paper feed tray and cassette It can cope with a large capacity such as 500 sheets.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a main part of a sheet feeding device according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram showing movement of a fulcrum portion when the bottom plate is rotated.
FIG. 3 is a main part configuration diagram of a paper feeding apparatus according to a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Frame 2 Bottom plate 5 Engagement pin 6 Coil spring 7 Arc-shaped slot 8 Feed roller L1 Arc L2 Approximate straight line

Claims (1)

By applying pressure to the sheet feeding roller and the sheet feeding roller on which a plurality of sheets of paper are stacked, a bottom plate that can be freely contacted and separated, and the bottom plate, the uppermost sheet stacked on the bottom plate is supplied. In a paper feeding device in an image forming apparatus having a bottom plate pressurizing mechanism in pressure contact with a paper roller,
The bottom plate is rotatably supported with one end portion as a fulcrum, and the fulcrum portion of the bottom plate has a center line that draws an arc centering on the end of the sheet stacking surface on the fulcrum portion side of the bottom plate. An elongated hole and an engaging pin engaged with the elongated hole,
From the full load to the arbitrary number of sheets, the end of the bottom plate is the center of the bottom plate so that the engagement pin moves through the long hole, and the bottom plate is the center of the bottom plate. The center of rotation of the bottom plate changes in two steps depending on the angle of the bottom plate and the amount of paper loaded so that the engaging pin located at the end of the elongated hole is the center of the bottom plate. Paper feeder.

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