JP3349635B2 - Paper cassette - 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 feed cassette which is attached to a paper processing apparatus such as a printer, a copying machine, etc., and is capable of accommodating various types of paper of different sizes.

[0002]

2. Description of the Related Art Conventionally, a paper feeding portion of a printer as described above has been demanded for its small size and light weight. Processing has been done. The paper feed cassette urges the paper loaded on the pressing plate to the paper feed roller by a biasing means such as a biasing spring, and separates and feeds the paper one by one by a rotation drive of the paper feed roller and a paper separating mechanism. In a paper feed cassette capable of accommodating various types of paper, a movable guide for precisely defining the position according to the paper size is provided.

In general, in such a sheet cassette, if the pressing force of the stacked sheets against the sheet feeding roller is too strong, the frictional force becomes large and double feed is liable to occur.
If the pressing force is too weak, there is a problem that the frictional force is reduced and non-feeding is likely to occur. Therefore, it is desirable that the pressing force of the loaded paper against the paper feed roller be constant regardless of the size of the loaded paper and the number of loaded paper. For this reason, conventionally, in a paper cassette in which various types of paper are stacked and stored, a technique for keeping the pressure contact force with respect to the paper feed roller constant regardless of the size of the stored paper and the number of stacked papers has been performed.

For example, Japanese Patent Publication No. 59-28501 discloses that
The pressing plate on which various sizes of paper are loaded is not made to have a length substantially equal to the length of the maximum size paper, but is set to a length enough to partially load the paper feeding side. Regardless, a technique for keeping the weight applied to the pressing plate constant has been disclosed. That is, by shortening the length of the pressing plate, the weight applied thereto is made constant regardless of the paper size, and the pressing force against the paper feed roller is made constant.

[0005]

However, there is the following problem in the paper feed cassette provided with the pressing plate for loading and storing only the front end side of the above-mentioned paper. The inclination of the pressing plate is increased as the sheets stacked thereon are fed, and the feeding side of the stacked sheets is bent upward. Due to the inclination of the pressing plate and the bending of the stacked sheets, the stacked sheets are shifted rearward as the number of sheets is reduced, and the press-contact position with respect to the sheet feeding roller is shifted to cause a shift in the sheet feeding timing, or the separation claw is not provided. The double feed may occur due to the separation.

Further, the weight of the paper loaded on the pressing plate is substantially constant irrespective of the size of the paper, but when the feeding side of the loaded paper is bent upward as the number of papers decreases. Then, the force of the paper stiffness is applied downward.
Therefore, when the number of stacked sheets is small, a pressing force by a spring greater than the weight of the sheet is required for the pressing plate, so that the pressing force is still not constant, and non-feeding and double feeding occur. .

According to the present invention, even when sheets of various sizes are accommodated, the pressure contact force to the sheet feed roller is kept constant to ensure the consistency of the leading end portion of the stacked sheets on the feeding side, and the double feed, non-feed, etc. It is an object of the present invention to provide a paper feed cassette that prevents the occurrence of a paper feed.

[0008]

The paper feed cassette of the present invention is constructed by embodying the principle described below.

[0009] The pressure contact force with which the loaded paper is pressed against the paper feed roller is P, the biasing force of the biasing means such as a biasing spring attached to the pressing plate is F, and the weight of the paper loaded on the pressing plate is F. If it is assumed that W, the pressing force P can be expressed by FW unless the weight or the like of the pressing plate is considered. Here, the urging force F by the urging spring is proportional to the amount of contraction thereof, that is, the number H of sheets to be stacked, and the weight W of the paper is proportional to the number H of sheets.

This relationship is shown in the graphs of FIGS. 1 (a) and 1 (b). In the graph of FIG. 1A, when the number of stacked sheets is 0, it indicates that the pressing plate is pressed against the sheet feeding roller by a certain force. In the graphs of FIGS. 1A and 1B, the graph of FIG. 1C actually shows the FW relationship. In this graph, the pressing force P is constant irrespective of the number of stacked sheets H, which is an ideal state for separating and feeding the stacked sheets.

However, as described above, since sheets of different sizes are accommodated in the sheet cassette, it is not possible to satisfy the relationship shown in the graph of FIG. Can not. This is because the weight changes as shown in FIG. 2A depending on the number of sheets H when the paper size is large or small. Therefore, if a sheet of the size shown in FIG. 2A is loaded on a pressing plate to which a pressing spring having the characteristics shown in the graph of FIG. 1A is attached, the pressing force P depends on the sheet size.
Changes as shown in FIG. 2B.

However, in most sheet separation systems, the allowable range of the pressing force P at which double feed or non-feed does not occur is as shown in FIG.
P1 and P2 shown in (c) are determined. Specifically, when the pressing force is less than P1, the frictional force between the sheet and the paper feed roller is weakened, and non-feeding is likely to occur. The frictional force between them increases, and double feed is likely to occur.
As is apparent from this graph, depending on the design mode such as the spring constant of the pressing spring and the coefficient of friction of the paper feed roller, the paper feed cassette is not fed, such as H1, H2,. There is a maximum allowable number of stacked sheets within a range where double feeding does not occur.

The paper feed cassette of the present invention finds out the principle as described above, and enables paper sheets of all sizes to be loaded on the pressing plate so as to ensure the consistency of the leading end of the loaded paper on the feeding side, so that the loaded paper sheets can be loaded. The gist is to regulate the number of sheets to be equal to or less than the maximum allowable number of sheets for each sheet size. That is, regardless of the sheet size, the sheet of the maximum number of sheets that does not cause double feeding or non-feeding is always loaded on the pressing plate of the sheet feeding cassette, regardless of the sheet size, while maintaining the consistency of the leading end on the feeding side. Therefore, non-feeding, double feeding, and the like are prevented.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. FIG. 3 is a view schematically showing a printer which is a sheet processing apparatus provided with the sheet cassette according to the present invention. The printer 1 includes a printing unit 2 that prints on paper and a paper feed cassette 5 that can supply paper to the printing unit one by one.
It has. The paper feed cassette 5 can store sheets of various sizes, and separates and feeds out the stacked sheets into one sheet via a rotation drive of a sheet feed roller 7 that contacts the uppermost sheet and a sheet separating mechanism (not shown). . Then, the fed-out sheet is conveyed to the printing unit 2 via a pair of conveying rollers 8, and the sheet on which printing has been performed is discharged to a discharge stacker 10 via a pair of conveying rollers 9.

In this case, the paper feed cassette 5 is
May be incorporated in advance, or as shown in the figure, may be incorporated in a paper feed unit 12 which is detachably attached to the printer 1.

Next, the configuration of the sheet cassette 5 will be described with reference to FIGS. On the frame 5a of the sheet cassette 5, a pressing plate 20 on which sheets of various sizes are stacked is rotatably supported at a base end 20h . A drive shaft 7a, which is rotatably driven by a drive unit (not shown) above the end of the pressing plate 20 in the paper feeding direction, and to which the paper feed roller 7 is fixed, is mounted on the frame 5a.
Are rotatably supported. The pressing plate 20 is provided between the feed roller 7 and the rear surface of the pressing plate 20 between the front end side of the pressing plate 20 and the frame 5a.
The urging means 22 for urging the paper toward the surface of the paper feed roller 7 is pressed against the outer peripheral surface of the paper feed roller 7.

A pair of side guides 25 are provided on the pressing plate 20 so as to be slidable in the sheet width direction by a universal mechanism (not shown) so as to regulate both sides according to the size of sheets to be stacked. The side guides 25 support separation claws 27 that contact the front edges of the sheets stacked on the pressing plate and separate one sheet of paper in the sheet feeding direction.

As described above, sheets of various sizes are stacked on the pressing plate 20, and a regulating means for regulating the number of sheets to be stacked is provided corresponding to each size. This restricting means restricts the number of sheets stacked on the pressing plate 20 to a maximum allowable number of sheets at which double feeding, non-feeding or the like does not occur for each size. , FIG.
As described with reference to FIG. 2 and the graph of FIG. 2, the setting is made in advance in consideration of the urging force of the urging means 22, the coefficient of friction of the paper feed roller 7, the weight of the pressing plate 20, and the like.

If the regulating means can regulate the number of sheets to be equal to or less than a predetermined number of sheets in accordance with the size of sheets to be stacked, the mounting position and the structure are not particularly limited, but the structure is simplified. Thus, it is preferable to use a rear end guide of the stacked sheets.

More specifically, as shown in FIG.
Are formed with positioning holes 20a to 20g for mounting rear end guides for regulating the rear end side in accordance with the size of sheets to be stacked, together with the side guides 25. In the figure, the rear end guide 30 is attached to the positioning hole 20a formed at the front end in the paper feeding direction so as to correspond to the minimum paper, and the rear end guide 30 is formed at the rear end in the paper feeding direction so as to correspond to the maximum paper. This shows a case where the rear end guide 31 is attached to the positioning hole 20g.

Each of the rear end guides and the positioning holes is configured to be detachable from the pressing plate 20 by, for example, a configuration as shown in FIG. That is, the rear end guide 30
Are a flat plate portion 30a, a positioning protrusion 30b, and a deformable protrusion 3 elastically deformable so as to sandwich the positioning protrusion 30b.
0c and a flange portion 30d formed at the tip of the deformable protrusion 30c. The positioning hole 20a is formed by holes 30a1 and 20a2 into which the protrusion 30b of the rear end guide 30 and the flange 30d are inserted. ing. The rear end guide 30 is attached to and detached from the positioning hole 20a by elastically deforming the deforming projection 30c.

The height of the flat plate portion 30a of the rear end guide 30 is
As described above, the setting is made in accordance with the height of the predetermined maximum number of sheets to be stacked for the sheets to be stacked. By setting the height of the flat plate portion 30a in such a manner, by stacking the number of sheets corresponding to the height, it becomes possible to separate the sheets within a range in which non-feeding, double feeding, and the like do not occur. .
In the configuration of the rear end guide, it is preferable to form a restricting portion 30e at the upper end of the flat plate portion 30a so as to be in contact with the surface of the stacked paper. By forming such a regulating portion 30e, the number of stacked sheets can be reliably regulated to be equal to or less than the maximum allowable number of stacked sheets. In addition, each other positioning hole 20b ~
A rear end guide of a similar configuration in which the height of the flat plate portion 30a differs according to the height of the maximum allowable stacking number is also detachably attached to 20g.

As shown in FIG. 4, the pressing plate 20 on which the plurality of rear end guides are mounted has one holding hole 20k for accommodating an unused rear end guide at a portion outside the paper stacking area. Preferably, at least one is formed. By forming such a holding hole, it is possible to prevent the rear end guide from being lost when not in use.

According to the paper cassette constructed as described above, when sheets of various sizes are stacked on the pressing plate 20, the number of sheets to be stacked is not fed by the rear end guide, so that double feeding does not occur. Can be regulated to a range. For example, when the urging force of the urging means 22 is adjusted to a large-size sheet,
The number of stacked sheets of paper having a smaller size is limited so that the pressing force is equal to or less than a range where double feeding does not occur. Also,
Sheets of all sizes are regulated by the flat portion of the rear end guide protruding from the pressing plate 20, so that the sheet does not shift backward when the number of stacked sheets is reduced, and the pressure contact position is changed and separated. Double feed, non-feed and the like due to detachment from the nail are prevented.

Although the embodiment of the paper feed cassette of the present invention has been described above, the present invention restricts the stacking amount to be equal to or less than a preset maximum allowable number according to the size of the sheets stacked on the pressing plate. In particular, if such a restriction is made, the configuration of the restriction means can be variously modified. For example, a regulating portion for regulating the sheet height may be configured to be detachable so as to be able to change the height position with respect to one rear end guide. Further, the rear end guide may be configured to be able to expand and contract along the height direction of the sheet and to maintain the height position according to the sheet size. With this configuration of the rear end guide, the number of rear end guides of the sheet cassette can be reduced. Furthermore, the configuration of other members other than the regulating means, for example, the configuration of a side guide, a paper separation system, and the like can be variously modified.

[0026]

According to the present invention, the consistency of the leading end portion of the stacked sheets on the feeding side is always ensured regardless of the sheet size, the number of stacked sheets for each sheet size, and the pressure contact force to the sheet feed roller is constant. Since the paper is restricted to a range where the paper can be stacked, double feeding, non-feeding, and the like are prevented when separating and feeding the stacked sheets.

[Brief description of the drawings]

FIG. 1A is a graph showing the relationship between the urging force of a pressing plate against a paper feed roller and the number of stacked sheets, FIG. 1B is a graph showing the relationship between the weight of paper and the number of stacked sheets, and FIG. , (A)
7A and 7B are graphs showing the relationship between the pressing force against the paper feed roller and the number of stacked sheets in the relationship between the graphs shown in FIGS.

FIG. 2A is a graph showing the relationship between the weight of paper and the number of stacked papers for paper of different sizes, and FIG.
In the relationship between the graph shown in FIG. 1A and the graph shown in FIG. 1A, a graph showing the relationship between the pressing force against the paper feed roller and the number of stacked sheets, and FIG. Graph showing the range.

FIG. 3 is a view schematically showing a printer which is a sheet processing apparatus provided with a sheet cassette according to the present invention.

FIG. 4 is a plan view illustrating a configuration example of a sheet feeding cassette.

FIG. 5 is a longitudinal sectional view of the sheet cassette shown in FIG. 4;

FIG. 6 is a perspective view showing a configuration example of a rear end guide.

[Explanation of symbols]

 Reference Signs List 5 paper feed cassette 7 paper feed roller 20 pressing plate 27 separation claw 30, 31 rear end guide

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-294471 (JP, A) JP-A-3-297737 (JP, A) Fully open 1983-184431 (JP, U) Really open 1988 161235 (JP, U) Japanese Utility Model 62-144840 (JP, U) Japanese Utility Model Application Hei 3-91427 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B65H 1/00-3 / 68

Claims (3)

(57) [Claims] 1. A sheet feeding roller for feeding stacked sheets of various sizes, a pressing plate for pressing the sheet against the sheet feeding roller, and a detachable and detachable member for the pressing plate to regulate a rear end of the sheet. together, stacking height according to the paper size of each is different to
The pressing force of the paper against the paper feed roller is
Loading on the pressing plate so that it is within the specified tolerance
The number of sheets to be
A paper cassette comprising a regulating rear end guide. 2. The storage device according to claim 1, wherein the pressing plate is provided with an accommodation portion for accommodating a rear end guide other than the sheet placement area when regulating a rear end of a sheet of a predetermined size. 2. The paper cassette according to 1. 3. The control device according to claim 1, wherein a restricting portion for restricting the stacking height of the paper is provided above the rear end guide.
Or the paper feed cassette according to 2.