JPH0967026A - Automatic paper feeding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automatic paper feeding device capable of constantly obtaining paper feeding pressure irrespective of the size and amount of the papers to be laminated on a pressing plate. SOLUTION: An automatic paper feeding device is provided with a bottom plate 2b, a pressing plate 3, a paper feeding roller 7a to separate and feed the laminated sheet loaded on the pressing plate 3, and a compression coil spring 5 which presses the pressing plate 3 against the paper feeding roller 7a, and energizes the laminated sheets loaded on the pressing plate 3 in an abutting manner. One end part of the compression coil spring 5 is fixed to a back side of the pressing plate 3, while the other end part is fixed to a rotatable spring contracting member 15. The diameter of the compression coil spring 5 is adjusted by rotating the spring contracting member 15 to change the spring constant according to the paper size.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic sheet feeder used for a sheet processing apparatus such as a printer, and more specifically,
The present invention relates to an automatic paper feeder having an adjusting mechanism capable of adjusting a paper feeding pressure with respect to a paper feeding roller according to a size of paper to be accommodated.

[0002]

2. Description of the Related Art An automatic paper feeder is configured to press sheets stacked on a pressing plate into contact with a paper feeding roller by a pressing spring.
It is configured to separate and feed the uppermost sheets one by one by rotating the sheet feeding roller. In this case, in order to stably separate and feed the sheets stacked on the pressing plate, the pressing force (feeding pressure) of the stacked sheets against the sheet feeding roller must be within a certain range regardless of the number of stacked sheets. . Normal,
When a large number of sheets are stacked on the pressing plate, the amount of contraction of the pressing spring is large, and the amount thereof decreases as the sheet is separated and fed. Therefore,
By setting the spring constant of the pressing spring appropriately,
It is possible to obtain a paper feed pressure in a substantially constant range regardless of the stacking amount.

However, the weight change due to the difference in the size of the sheets stacked on the pressing plate cannot be dealt with by appropriately setting the spring constant. That is, the total weight of the small size paper is smaller than that of the large size paper.
In this case, if the spring constant is set in conformity with the small size paper, the paper feed pressure becomes too low for the large size paper, and problems such as double feeding occur.

To solve this problem, Japanese Patent Laid-Open No. 55-
In No. 84735, an inclined cam is provided on the back surface of the pressing plate, and the pressing spring is moved along the inclined cam in conjunction with the movement of the side guides that are slid in the width direction according to the paper size, and the inclined cam is supported. Then, the technique of changing the compression length of the pressing spring is disclosed. Further, Japanese Patent Application Laid-Open No. 55-84736 discloses a technique of changing the compression length of the pressing spring by moving the lower end bearing surface of the pressing spring up and down according to the size of the paper placed on the pressing plate. .

[0005]

In the automatic paper feeder disclosed in the above publication, the compression length of the pressing spring is simply changed according to the paper size, and the spring constant is constant. When the spring constant is constant as described above, the sheet feeding pressure may change depending on the sheet size depending on the sheet size, and the separation and feeding becomes unstable.

This will be specifically described with reference to FIG. In this graph, the horizontal axis represents the amount of paper loaded and the vertical axis represents the vertical force. As described above, the compression length of the pressing spring only changes according to the paper size, and the spring constant is constant. Therefore,
The upward force (F) by the pressing spring in the case of A3 size (large size) and the upward force (f) by the pressing spring in the case of B5 size (small size) are both proportional to the loading amount, and the loading amount is The inclinations of the two become equal only when the force at 0 is different. On the other hand, the downward force (W,
w) is B5 for A3 size according to the paper loading amount
It gradually becomes larger than the size.

The pressing force (P, P
p) is a combination of the upward force (F, f) due to the pressing spring and the downward force (W, w) due to the weight of the paper. As is apparent from the graph, for example, even if the spring constant is set to be suitable for the B5 size, in the A3 size, the pressing force P against the sheet feeding roller is not constant according to the stacking amount, and as a result, Separate feeding becomes unstable. SUMMARY OF THE INVENTION It is an object of the present invention to provide an automatic sheet feeding device that can always obtain a constant sheet feeding pressure regardless of the size of sheets stacked on a pressing plate and the stacking amount.

[0008]

In order to solve the above-mentioned problems, an automatic sheet feeder according to the present invention comprises a bottom plate, and a pressing plate which is movably supported on the bottom plate and on which stacked sheets are placed. ,
A sheet feeding roller that separates and feeds the stacked sheets placed on the pressing plate, and presses the pressing plate toward the sheet feeding roller to bring the stacked sheets placed on the pressing plate into contact with the sheet feeding roller. A compression coil spring for urging is provided, and one end of the compression coil spring is fixed to the back surface of the pressing plate, and the other end is fixed to a rotatable spring diaphragm member. The feature is that the winding diameter of the compression coil spring can be adjusted.

According to the above construction, the compression coil spring arranged between the bottom surface and the back surface of the pressing plates on which the sheets are stacked is rotated by rotating the spring diaphragm member rotatably provided on the bottom plate side. The winding diameter can be changed. When the winding diameter of the compression coil spring changes, the spring constant itself changes. Therefore, by setting the spring constant of the compression coil spring to an optimum value for each paper size so that the paper feed pressure to the paper feed roller is within a certain range, a constant paper feed pressure is maintained regardless of the paper size and the stacking amount. Is obtained.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of an automatic sheet feeder according to the present invention will be described in detail below with reference to the drawings. FIG. 1 is a plan view showing the outline of an automatic paper feeder.
The automatic sheet feeding device 1 has a cassette body 2 in which sheets of various sizes are stacked and accommodated, and a pressing plate 3 on which stacked sheets are placed is provided at a substantially central portion of both side plates 2a of the cassette body 2.
Are rotatably supported around the base end. Press plate 3
A compression coil spring 5 for urging the pressing plate 3 upward with a support shaft as a center is arranged between the center portion of the front end and the bottom plate 2b of the cassette body. A paper feed roller 7a fixed to a paper feed roller shaft 7 is arranged above the front end side of the pressing plate 3, and the sheets stacked on the pressing plate 3 are fed by the urging force of the compression coil spring 5. The roller 7a is contacted and urged. In this embodiment, a pair of paper feed rollers 7a is provided on the paper feed roller shaft 7 at a predetermined interval.

The sheets stacked on the pressing plate 3 are regulated at the rear end side by the rear end guides 9 and at both sides by the side guides 10. The rear end guide 9 is attachable to and detachable from the bottom plate 2b by a large number of engaging holes 2c formed in the bottom plate 2b at predetermined intervals along the longitudinal direction, and the position is changed according to the paper size. be able to. The side guide 10 can be moved along the axial direction of the paper feed roller shaft 7 by the universal mechanism 12, and its position is changed according to various sizes of paper placed on the pressing plate 3. It is configured to be able to.

The universal mechanism 12 is provided with racks 13 and 14 which are formed from the lower ends of the side guides 10 so as to respectively extend in the horizontal direction at intervals at intervals in the sheet feeding direction, and the racks 13 and 14. And a pinion 15 that is rotatably supported by the bottom plate 2b so that the axial direction is vertical. Therefore, if either side guide is operated along the axial direction, both side guides move integrally due to the relationship between the rack and the pinion. A separation claw 17 extending forward is attached to each of the side guides 10, and engages with both ends of the topmost sheet of the stacked sheets placed on the pressing plate, and the sheet feeding roller. Along with the rotational driving of 7a, one sheet is separated.

As shown in the enlarged view of FIG. 2, the compression coil spring 5 has one end fixed to the back surface of the pressing plate 3 and the other end fixed to the upper surface of the pinion 15. in this case,
The pinion 15 is rotationally driven by the movement of the side guide according to the paper size. Due to the rotational drive of the pinion 15, the compression coil spring 5 receives the throttling action or the releasing action from the state where the compression coil spring 5 has been throttled. Thus, when the compression coil spring is subjected to the throttling action / release action, the winding diameter and the number of turns of the compression coil spring itself change.
That is, when the compression coil spring is narrowed down, the winding diameter is small, the number of windings is large, and as a result, the spring constant is large. Conversely, when the release action is applied from this state, the winding diameter is large, the number of windings is small, and as a result, the spring constant is small.

It is the rotational drive of the pinion 15 that narrows and releases the compression coil spring 5.
As described above, the rotation amount of 5 depends on the movement amount of the side guide 10 according to the size of the sheet placed on the pressing plate. Here, when the compression coil spring 5 is narrowed down and released,
The relationship with the movement of the side guide 10 will be described with reference to FIG.

FIG. 3A shows a state in which large size sheets, for example, A3 size sheets are stacked and placed on the pressing plate 3.
The side guide 10 is in the most open state, and at this time, the compression coil spring 5 is set to be the most narrowed, the winding diameter is small, and the number of windings is large. That is, when the side guide 10 is widened to the Wa width, the compression coil spring 5 receives the rotating action of the pinion 15 on the width-opening side and has a small winding diameter and a large number of windings. Mounted between. Therefore, FIG.
As shown in (b), in order to stack small size sheets, for example, B5 size sheets, on the pressing plate 3, the side guide 10 is set to W.
When the width of the compression coil spring 5 is reduced to b, on the contrary, the winding diameter is small and the number of windings is increased.

As described above, when a large size sheet is stacked on the pressing plate 3, the spring constant of the compression coil spring 5 is increased, and when a small size sheet is stacked, the spring constant is reduced. Can be changed to Then, by changing the spring constant according to the paper size, it becomes possible to make the paper feed pressure to the paper feed roller 7a substantially constant regardless of the paper size and the stacking amount. This is shown in FIG.
Based on (b), A3 size and B5 size will be specifically described.

As described above, the compression coil spring changes so that the spring constant increases in accordance with the increase in the size of the sheets stacked on the pressing plate. Therefore,
The upward force (F) of the compression coil spring for the A3 size is proportional to the load (f) as compared with the upward force (f) of the compression coil spring for the B5 size, but its inclination is large. In addition, since the compression length of both is the same when the loading amount is 0, the forces of both are the same at that time. On the other hand, the downward force (W, w) due to the weight of the paper is gradually larger in the A3 size than in the B5 size according to the stacking amount of the paper. This is similar to the case of FIG.

The pressing force of the paper against the paper feed roller (P,
Similarly to the case of FIG. 7A, p) is the upward force (F, f) due to the pressing spring and the downward force (W, due to the weight of the paper).
w) together. As is clear from the graph, by changing the spring constant, it is possible to make the pressing force (P, p) against the paper feed rollers of each size constant regardless of the load amount. In this case, the configuration of the compression coil spring, the number of teeth of the rack and the pinion, the positional relationship, and the like are set so that the optimum spring constant is set according to the size of the sheet placed on the pressing plate.

As described above, since the paper feed pressure can be made constant regardless of the paper size and the stacking amount, the paper can be always separated and fed stably. Further, since the compression length of the compression coil spring is not changed according to the size of the sheet placed on the pressing plate, the vertical size of the cassette member is not increased. Further, since the compression coil spring is composed of one piece, it is inexpensive, and the spring pressure decreases smoothly with the decrease in the number of sheets on the pressing plate, and the optimum spring pressure is always obtained.

According to the above configuration, the compression coil spring 5
When the number of turns is increased and the number of turns is increased, a force for rotating the pinion 15 acts due to the restoring force, and the both side guides 10 receive a force that moves in a direction in which they are pulled toward each other. Therefore, it is preferable to provide the stopper means 30 on the side guide 10 so as to fix the side guide 10, for example, as shown in FIG.

This stopper means 30 is used as the side guide 1.
No. 0, an upper guide 31 and a lower guide 32 having guide holes, and a locking member that can slide vertically in the guide holes of these guides and is always urged downward by a compression spring 35. 37 and. On the other hand, locking teeth 40 are formed on the bottom plate 2b of the cassette body 2 so that the tips of the locking members 37 can be engaged. Accordingly, the side guide 10 is moved and aligned while lifting the locking member 37 against the biasing force of the compression spring 35, and the locking member 37 is engaged with the locking tooth 40. It is possible to prevent the side guide 10 from moving due to the restoring force of 5. Of course, the stopper means is not limited to the configuration shown in the figure and can be variously modified as long as the movement of the side guide 10 due to the restoring force of the compression coil spring 5 can be prevented.

The embodiment of the present invention has been described above.
The present invention is not limited to the above embodiment, and can be variously modified. In the above-described embodiment, the spring throttle member that changes the spring constant of the compression coil spring 5 is configured by the pinion of the universal mechanism of the side guide, but such a spring throttle member is shown in FIGS. 5 and 6, for example. As shown, it may be provided separately from the pinion.

In this embodiment, the spring throttle member 50 is used.
Is rotatably supported on the bottom plate 2b of the cassette body 2,
It is configured as a gear (spring diaphragm gear) having irregular teeth formed around it. The end of the compression coil spring 5 is fixed to the upper surface of the spring diaphragm gear 50, and a dial 52 rotatably supported by the bottom plate 2b is meshed with the concave and convex teeth. A part of the dial 52 projects from a window 2f formed on the front wall 2e of the cassette body, and can be manually rotated. As shown in FIGS. 6A and 6B, the outer circumference of the dial 52 is set at a predetermined position so that the spring diaphragm gear 50 can be rotated to an optimum position for the size of the paper placed on the pressing plate 3. A display corresponding to the paper size is attached. That is, for example, when "A3" is displayed as shown in FIG. 5A, the spring diaphragm gear 50 is narrowed down, and the spring constant of the compression coil spring 5 increases.
As shown in FIG. 6B, when "B5" is displayed, the spring diaphragm gear 50 is released and the spring constant of the compression coil spring 5 becomes smaller.

As described above, the position of the spring diaphragm member can be variously changed in accordance with the position where the compression coil spring 5 is provided. Of course, also in this embodiment, the spring diaphragm gear 50 is driven by the restoring force of the compression coil spring.
It is preferable that the dial 52 is appropriately provided with a stopper to prevent the rotation of the dial. Further, by appropriately interposing another gear between the spring diaphragm gear 50 and the dial 52, the rotation of the spring diaphragm gear 50 can be accelerated / decelerated, and the spring constant can be reduced by a slight amount of rotation of the dial 52. It is also possible to change.

[0025]

As described above, according to the present invention,
Regardless of the size of the paper loaded on the pressing plate and the amount of paper loaded, it is possible to always obtain a substantially constant paper feed pressure for the paper feed roller, and to stably separate and feed the paper.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of an automatic paper feeder according to the present invention.

FIG. 2 is an enlarged perspective view showing a portion of a universal mechanism that slides a side guide of the automatic paper feeder shown in FIG.

3 is a front view of stacked sheets placed on a pressing plate of the automatic sheet feeder shown in FIG. 1, FIG.
FIG. 6B is a diagram showing a state in which a small size sheet is placed.

FIG. 4 is a diagram showing a configuration example of stopper means provided in the automatic paper feeder shown in FIG.

FIG. 5 is a plan view showing another embodiment of the automatic paper feeder according to the present invention.

FIG. 6 is a front view of stacked sheets placed on a pressing plate of the automatic sheet feeder shown in FIG. 5, (a) showing a large-sized sheet;
FIG. 6B is a diagram showing a state in which a small size sheet is placed.

7A and 7B are graphs showing the relationship between the urging force of a spring, the weight of a sheet, and the sheet feeding pressure with respect to a sheet feeding roller. FIG. 7A is a relationship in the related art and FIG. Indicates.

[Explanation of symbols]

1 ... Automatic paper feeder, 2 ... Cassette body, 2a ... Both side plates,
2b ... bottom plate, 3 ... pressing plate, 5 ... compression coil spring, 7a ...
Paper feed roller, 10 ... Side guide, 15 ... Pinion (spring diaphragm member), 30 ... Stopper means, 50 ... Spring diaphragm gear (spring diaphragm member), 52 ... Dial.

Claims (2)

[Claims] 1. A bottom plate, a pressing plate which is movably supported on the bottom plate and on which stacked sheets are placed, and a sheet feeding roller which separates and feeds the stacked sheets placed on the pressing plate, An automatic paper feeding device comprising: a compression coil spring that presses the pressing plate toward a paper feeding roller to urge the stacked sheets placed on the pressing plate into contact with the paper feeding roller. One end is fixed to the back surface of the pressing plate, the other end is fixed to a rotatable spring diaphragm member, and the winding diameter of the compression coil spring can be adjusted by rotating the spring diaphragm member. Automatic paper feeder. 2. The pressing plate is provided with side guides that move in the width direction so as to regulate both sides of the stacked sheets placed on the pressing plate, and the spring diaphragm member is provided with a side guide of the side guides. The automatic paper feeder according to claim 1, wherein the automatic paper feeder rotates in association with movement.