JPH08244990A - Paper feeding device and image forming device - Google Patents

Abstract

PURPOSE: To prevent generation of poor feed of paper by restraining change of the paper feed pressure of sheet material, even if the sort of sheet material is different or the quantity of sheet material loaded in a cassette is changed. CONSTITUTION: This paper feed device is provided with an intermediate plate 2 (sheet material holding means) capable of pilingly loading a plurality of sheet materials S1, a swing shaft 2a (support member) and a supporting member 7 (support member) supporting the intermediate plate 2 capably of being swung, and a spring 3 (energization member) bringing the sheet material in contact with a separation claw 6 (sheet, material separating means) by energizing one end of the intermediate plate 2 while setting the swing shaft 2a and the position where the sheet material holding means is supported with the supporting member 7 as fulcrums so as to give paper feed pressure to it, and the supporting position of the supporting member supporting the intermediate plate 2 is changed according to the loading quantity of the sheet material S1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding device which is applied to an electrophotographic apparatus, an electrostatic recording apparatus, an image forming apparatus such as a laser beam printer, or the like, and supplies a sheet material.

[0002]

2. Description of the Related Art An example of an image forming apparatus using a conventional sheet material is shown in FIG.

In FIG. 12, 101 is a main body of an image forming apparatus showing a conventional example, 102 is a paper feed cassette for accommodating sheet material S1, and the sheet material S1 is loaded therein, and the image formation is carried out in the direction of arrow P. Mounted on the device 101. 1
Reference numeral 03 is a paper feed roller, 104 is a conveyance guide, 105 is a registration roller that conveys the sheet material S1 at a predetermined timing, 106 is a process cartridge, and the photosensitive drum 1
06a, primary charger (not shown), developing device (not shown),
A cleaning device (not shown) is built in.

Reference numeral 107 is a transfer roller, 108 is a conveyance guide, 109 is a fixing device, 110 is a fixing entrance guide, and 1 is a fixing guide.
11 is a fixing roller, 112 is a pressure roller, 113 is a fixing paper discharging roller, 114 is a paper discharging roller, 115 is a paper discharging tray on which printed sheet material S1 is stacked, 116 is a scanner unit which scans the laser beam L, Reference numeral 117 is a mirror that guides the laser light L to the photosensitive drum 106a.

Next, the paper feed cassette 1 will be described with reference to FIG.
The structure of 02 will be described.

FIG. 13 is a sectional view of a sheet feeding cassette showing a conventional example. 201 is a cassette tray, and 202 is an intermediate plate. The sheet material S1 is stacked on the intermediate plate 2, and at the same time, the sheet material S1 is held at a predetermined height, and the rotation center 202
The cassette tray 2 is rotatably centered around a.
It is attached to 01. Reference numeral 203 denotes a spring, which presses the intermediate plate 202 upward so as to apply a pressure required for sheet feeding to the sheet material S1, that is, a sheet feeding pressure. Reference numeral 204 denotes a trailing edge regulation plate that regulates the vertical position of the sheet material S1. Reference numeral 205 denotes a separation claw, which is rotatably installed with a rotation center 205a as a rotation center. When the sheet material S1 is fed by the sheet feeding roller 103,
It has a function of separating the sheet materials S1 one by one.

Here, as described above, the sheet material S
1, the sheet feeding pressure is applied by the spring 203, but generally, when the sheet feeding pressure is weak, the frictional force between the sheet feeding roller 103 and the sheet material S1 is reduced. Therefore, the paper feed roller 103 is likely to slip and cause a paper feed failure. Further, when the paper feed pressure is strong, so-called double feeding is likely to occur, in which two or more sheet materials S1 are fed.

Therefore, in order to stably feed the sheet materials S1 one by one, an appropriate feeding pressure is required.

In the above configuration, when a print instruction is issued by a host computer (not shown) connected to the image forming apparatus 101, the paper feed roller 10
3 rotates, and the sheet material S in the paper feed cassette 102 is rotated.
One sheet of 1 is fed and guided to the registration roller 105 by the conveyance guide 104. The registration roller 1
Reference numeral 05 denotes the photosensitive drum 10 by the laser light L.
The sheet material S1 is conveyed to the transfer portion in synchronization with the image information formed on the sheet 6a, and the image is transferred onto the sheet material S1. The sheet material S1 after the transfer is further conveyed to the fixing device 109, and a fixing process is performed by heat and pressure to fix an image on the sheet material S1. After the fixing process, the sheet material S1 is discharged from the fixing device 109 by the fixing paper discharge roller 113, and is discharged and stacked on the paper discharge tray 115 by the paper discharge roller 114.

[0010]

However, in the above-mentioned conventional example, the intermediate plate 2 for applying the sheet feeding pressure is used.
The pressure applied by the spring 203 to 02 is constant at the same stacking height regardless of the type of the sheet material S1.

Therefore, when a sheet material S1 having a high density is stacked, the intermediate plate 202 made of the sheet material S1.
Since the moment applied to the sheet becomes large and the sheet feeding pressure becomes weak, defective sheet feeding easily occurs, and when the sheet material S1 having a low density is stacked, the sheet material S1
Due to this, the moment applied to the intermediate plate 202 becomes small and the paper feeding pressure becomes strong, so that there is a drawback that double feeding easily occurs.

In a multi-size cassette in which sheet materials of different sizes can be placed by moving a partition plate (not shown) provided in the paper feeding cassette 102, the same as above depending on the size of the sheet material. There was a change in the paper feed pressure.

As means for reducing the variation of the sheet feeding pressure depending on the type of the sheet material, the cassette 201 of FIGS. 14 (a) and 14 (b) has the center of rotation 2a of the intermediate plate 2 in the sheet feeding direction. The sheet material is moved to the downstream side in the sheet conveying direction in the direction of arrow A1, and the position of the rotation center 2a of the intermediate plate 2 is set to the intermediate plate 2.
Also, when the position is close to the center of gravity of the sheet material S1, the influence of the moment due to the weight of the sheet material is reduced.

However, as shown in FIGS. 14 (c) and 14 (d), the height of the cassette 201a is increased (from h101 to h102), and at the same time, the sheet material S1 and the separation claws are loaded and unloaded. Angle with 105 (from a101 to a
There is a drawback that the difference of 102) becomes large and jams and double feeding easily occur.

Here, the magnitude of the variation in sheet feeding pressure due to the difference in sheet material density will be obtained.

The sheet material A (75 g / m ² ) has a stacking height of 50 mm, and the weight of paper is about 2400 g. The sheet material B (75 g / m ² ) has a stacking height of 50 mm, about 18 mm.
It is assumed that the result of 00g was obtained.

In order to simplify the calculation, please refer to FIG.
From the rotation center 202a of the middle plate 202,
Distance to the camera 103₁ = 280 mm, the middle plate 20
2 rotation center 202a to the middle plate 2 of the spring 203
Distance l to the pressurizing position to 02 ₂ = 280 mm, in the above
The length of the plate 202 (from the rear end of the middle plate 202 to the separation claw)
205 Distance to the tip) l₃ = 280 mm, the sheet
Length of material S1 (from the rear end regulation plate 204 to the separation claw 2
05 Distance to the tip) l_Four = 280 mm, the middle plate 20
The weight of 2 is 600 g, and the sheet material S1 is fully loaded.
Height t = 50 mm, suitable paper feeding pressure is 300 g, or
The spring 203 is 1650 g when fully loaded and 60 when fully loaded.
The intermediate plate 202 is pressed with a force of 0 g to maintain a constant spring constant.
If it has, the feed pressure of sheet material A and sheet material B
Is as shown in FIG.

In the graph of FIG. 15, the horizontal axis indicates the sheet material S1.
And the vertical axis is the paper feed pressure. It can be seen that when the number of sheets is small, the influence of the weight of the sheet material is small, so that it is possible to realize an appropriate sheet feeding pressure, but as the load becomes closer, the influence of the density difference of the sheet material S1 becomes large. The sheet feeding pressure is 150 for sheet material A when stacking 50 mm.
In the case of the sheet material B, 450 g
The sheet feeding pressure rises up to g, and a difference of 300 g occurs in the sheet feeding pressure between the two.

Further, it is obvious that a difference occurs in the sheet feeding pressure even when the sheet materials have different sizes.

The present invention has been made to solve the above-mentioned problems of the prior art. The purpose of the present invention is to change the type of sheet material or to change the amount of sheet material loaded in the cassette. Even in such a case, it is necessary to suppress a change in the sheet feeding pressure of the sheet material and prevent the occurrence of sheet feeding failure.

[0021]

In order to achieve the above object, in the present invention, a sheet material holding means capable of stacking a plurality of sheet materials, and the sheet material holding means can be swung. And a supporting member for supporting the sheet material holding means, and a position of the supporting member supporting the sheet material holding means as a fulcrum to urge one end of the sheet material holding means to bring the placed sheet material into contact with the sheet material separating means. And a biasing unit that applies a sheet feeding pressure, and moves a position of the support member that supports the sheet material holding unit.

Further, it is preferable that the position of the supporting member for supporting the sheet material holding means is moved in a direction to reduce the change of the sheet feeding pressure in accordance with the stacking amount of the sheet material.

It is also preferable that the position of the supporting member for supporting the sheet material holding means is moved in a direction in which the inclination angle of the sheet material holding means becomes smaller according to the load amount of the sheet material holding means.

A plurality of the supporting members are provided on the path moved in a direction to reduce the change of the sheet feeding pressure corresponding to the stacking amount of the sheet material, and the sheet material holding means is provided when the stacking amount of the sheet material changes. The supporting member for supporting is changed. .

It is also preferable to equip the paper feeding cassette with this paper feeding device.

Further, it is also preferable that the image forming apparatus is provided with the above-mentioned sheet feeding device and the image forming means for forming an image on the sheet material fed from the sheet feeding device.

[0027]

In the sheet feeding device configured as described above, it is possible to change the sheet feeding pressure of the sheet material contacting the sheet separating means by moving the position of the supporting member that supports the sheet material holding means. Become.

Further, the position of the supporting member for supporting the sheet material holding means is moved in a direction in which the change of the sheet feeding pressure is reduced corresponding to the stacking amount of the sheet material, so that the variation of the sheet feeding pressure can be suppressed.

Further, the position for supporting the sheet material holding means of the supporting member is moved in a direction in which the inclination angle of the sheet material holding means becomes smaller in accordance with the stacking amount of the sheet material holding means, whereby the sheet material sheet separating means is moved. Reduce the contact angle with.

By providing a plurality of supporting members on the path moved in the direction of reducing the change of the sheet feeding pressure corresponding to the stacking amount of the sheet material, the supporting member abutting corresponding to the stacking amount of the sheet material is provided. The member is replaced, and the change in the sheet feeding pressure of the sheet material is suppressed.

By providing this paper feeding device in the paper feeding cassette, it becomes possible to make the paper feeding cassette with little change in the paper feeding pressure.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to illustrated embodiments.

(First Embodiment) FIGS. 1 and 2 show a first embodiment of the present invention. 1 and 2 are cross-sectional explanatory views of a sheet feeding cassette to which the present invention is applied as an embodiment. FIG. 1 shows the sheet feeding cassette when it is fully loaded, and FIG.

1 and 2, 1 is a cassette tray, 2 is an intermediate plate as a sheet material holding means, and a sheet material S
1 is loaded on the intermediate plate 2 and, at the same time, the sheet material S1
Is attached to the cassette tray 1 so as to be swingable on a swing shaft 2a serving as a support member for holding and supporting at a predetermined height.

Reference numeral 3 is a spring as an urging means, which presses the intermediate plate 2 upward so as to apply a sheet feeding pressure to the sheet material S1. Reference numeral 4 denotes a trailing edge regulation plate that regulates the position of the sheet material S1 in the vertical direction.

Paper feed roller 5 as sheet material separating means
Similarly, the separating claw 6 that is rotatably provided by the rotating shaft 6a as the sheet material separating means separates the sheet material S1 urged by the spring 3 by the separating claw 6 from both ends of the sheet material S1. By pressing and pressing the paper feed roller 5, the sheet material S1
Separately supply each sheet.

In the present embodiment, 7 is a supporting member provided on the spring 3 side of the swing shaft 2a as another supporting member, and is reduced by a predetermined amount from the state in which the sheet material S1 is fully loaded. Up to this, the intermediate plate 2 is swingably supported.

In the above construction, when the sheet material S1 is loaded in a large amount as shown in FIG. 1, the supporting member 7 contacts the bottom surface of the intermediate plate, and the intermediate plate 2 is centered on the supporting member 7. Rock. At this time, the support member 7 is fixed to the swing shaft 2a.
Since it is located closer to the center of gravity of the intermediate plate 2 and the sheet material S1, the influence of the density difference of the sheet material S1 is less, and the difference of the sheet feeding pressure due to the density difference of the sheet material S1 shakes the swing shaft 2a. It will be less than when centered on the motion.

That is, in this embodiment, since the position where the intermediate plate 2 is supported is moved from the swing shaft 2a to the support member 7, the intermediate plate 2 is moved in the direction in which the change in the sheet feeding pressure is reduced. .

Further, as shown in FIG. 2, paper is fed,
When the stacking amount of the sheet material S1 decreases and the stacking amount of the sheet material S1 decreases to a certain prescribed amount, the supporting member 7 becomes the intermediate plate 2
The oscillating shaft 2a serves as the oscillating center of the intermediate plate 2 away from the bottom surface of the slab. At this time, since the stacking amount of the sheet material S1 is small, the swing center of the intermediate plate 2 is at the center of the intermediate plate 2 and the sheet material S.
Even if the sheet moves from the position of the center of gravity of the sheet 1 to a position away from the spring 3 as the biasing means, the variation in the sheet feeding pressure due to the difference in the density of the sheet material S1 is small.

Here, an example of the sheet feeding pressure in the sheet feeding cassette having the configuration of this embodiment will be shown. In FIG. 1, the distance l ₁ from the swing shaft 2a of the intermediate plate 2 to the sheet feeding roller 103 is 280 m.
m, the distance l ₂ from the swing shaft 2a of the middle plate 2 to the pressing position on the middle plate 2 of the spring 3 is 280 mm, and the length of the middle plate 2 (the middle plate 2
Distance from rear end to tip of separation claw 6) l ₃ is 280 m
m, the length of the sheet S1 (distance from the rear end regulation plate 4 to the tip of the separation claw 6) l ₄ is 280 mm, the support member 7 to the middle plate 2
The distance x to the swing axis 2a of the sheet is 30 mm, and the sheet material S
When the loading amount of No. 1 is 20 mm, the supporting member 7 hits the bottom surface of the intermediate plate 2, the weight of the intermediate plate 2 is 600 g, the stacking height t of the sheet material S1 when it is fully loaded is 50 mm, and an appropriate feeding amount is provided. Paper pressure is 300g, and the spring 3 is 1 when fully loaded.
When the paper feed pressure is calculated under the setting that the intermediate plate 2 is pressed with a force of 490 g and 600 g when it is little loaded, and the spring constant is constant, the paper feed pressure of this paper feed cassette is as shown in FIG. Therefore, the maximum difference in sheet feeding pressure between the sheet material A and the sheet material B is 264 g, and the sheet feeding pressure of the sheet feeding cassette in which the fulcrum of the intermediate plate 2 is only the swing shaft 2a (see FIG. 15). It is possible to reduce variations in the paper feed pressure as compared with the above (see), and it is effective in preventing paper feed failure and double feed.

As shown in FIG. 4, the cassette 1 (FIGS. 4 (a) and 4 (b)) of this embodiment and the cassette 1a having one swing shaft 7a at the same position as the supporting member 7 (see FIG. c),
Comparing with (d), the height h1 of the cassette 1 can be made smaller than the height h2 of the cassette 1a.

Further, since the difference between the angles formed by the sheet material S1 and the separating claw 6 when the sheet material S1 is fully loaded and when the sheet material S1 is lightly loaded is as small as a1 <a2, it is possible to prevent defective feeding due to an excessively large separating angle. Is also effective.

Therefore, since the position where the intermediate plate 2 is supported moves from the support member 7 to the swing shaft 2a, the inclination angle of the intermediate plate 2 becomes smaller.

In the calculation of the sheet feeding pressure in this embodiment, the sheet feeding pressure of the sheet material A is set to 300 g to 170 g, and the sheet feeding pressure of the sheet material B is set to 300 g to 434 g. The position, height, and swing axis 2 of the support member 7
It can be changed by adjusting parameters such as a, the spring constant of the spring 3 and the strength of the spring.

(Second Embodiment) FIGS. 5, 6 and 7 show a second embodiment of the present invention. 5 to 7 are cross-sectional explanatory views of a paper feed cassette to which the present invention is applied as the second embodiment.
5 to 7, reference numeral 21 is a cassette tray, 22 is an intermediate plate, and 27 and 28 are supporting members.
A plurality of supporting members are installed in the embodiment.

In this embodiment, the support member 27 is the support member 2
It is located closer to the spring 23 (in the direction of arrow A) than 8 and is higher in height.

With the above-mentioned structure, as in the first embodiment, as shown in FIG. 5, when the load amount of the sheet material S1 is large, the support member 27 contacts the bottom surface of the intermediate plate 22, The plate 2 swings around the support member 27. At this time, the support member 27 includes the swing shaft 22a and the support member 28.
Since it is located closer to the center of gravity of the middle plate 22 and the sheet material S1, the density difference of the sheet material S1 has less influence even if the stacking amount of the sheet material S1 is large.
The difference in sheet feeding pressure due to the difference in density is smaller than that when the swing shaft 22a and the support member 28 are used as swing centers. Further, when the sheet is fed and the stacking amount of the sheet material S1 is reduced and the stacking amount of the sheet material S1 is reduced to a predetermined amount, the supporting member 27 is moved from the bottom surface of the intermediate plate 22 as shown in FIG. The support member 28 is separated from the bottom surface of the middle plate 22,
Becomes the center of swing. When the sheet is fed further and the stacking amount is reduced, the supporting member 28 is also separated from the bottom surface of the middle plate 22, and the swing shaft 22a becomes the swing center of the middle plate 22.

Here, an example of the sheet feeding pressure of the sheet feeding cassette having the configuration shown in this embodiment will be shown. As shown in FIG.
The distance l ₁ from the fulcrum to the paper feed roller 5 is 280 mm,
The distance l ₂ from the swing shaft 22a of the middle plate 22 to the pressing position on the middle plate 22 of the spring 23 is 280 mm, the length of the middle plate 22 (the distance from the rear end of the middle plate 22 to the tip of the separation claw 6). l ₃ is 280 mm, the length of the sheet material S1 (the distance from the rear end regulating plate 4 to the tip of the separating claw 6) l ₄ is 280 mm, the supporting member 2
When the distance x ₁ from 7 to the swing shaft 22a is 75 mm, the distance x ₂ from the support member 28 to the swing shaft 22a is 50 mm, and the loading amount of the sheet material S1 is 20 mm and 5 mm,
The support member 27 and the support member 28 respectively contact the bottom surface of the middle plate 22, and the spring 23 presses the middle plate 22 with a force of 1160 g when fully loaded and 600 g when lightly loaded, and the spring 23 has a constant spring constant. When the paper pressure is calculated, the paper feed pressure of this paper feed cassette is as shown in FIG. 8, and the difference between the paper feed pressures of the sheet material A and the sheet material B is 196 g at the maximum, which is similar to the first embodiment. At the position of the support member 27, the middle plate 2
Compared with a cassette having two swing centers, the height of the cassette tray 21 is smaller, and the angle formed by the sheet material S1 and the separating claw 6 at the time of full loading and less loading is smaller, and the sheet material S1 is smaller. It is possible to suppress the change in the sheet feeding pressure due to the difference in the density of the sheet, and it is possible to prevent the sheet feeding failure and the double feeding.

Further, similarly to the first embodiment, the support members 27,
The paper feed pressure can be adjusted by changing the parameters of the support member 28, the spring 23, and the like.

In the present embodiment, the supporting members are provided at two places in addition to the swing shaft 22a, but the present embodiment is not limited to this, and is characterized in that a plurality of supporting members are provided. It is a thing.

The other structure and operation are the same as those of the first embodiment described above, and therefore, the same components are designated by the same reference numerals and their description is omitted.

(Third Embodiment) FIGS. 9 and 10 show a third embodiment of the present invention. 9 and 10 are cross-sectional views of a paper feed cassette embodying this embodiment. 9 and 10,
Reference numeral 31 is a cassette tray, and 32 is an intermediate plate. Reference numeral 37 denotes a support member. In this embodiment, the support member 37 has a cam surface 37a as compared with the first embodiment, and the cam surface 37a is closer to the spring 33 (direction of arrow A). It has a shape that increases in height. Further, in this embodiment, the swing shaft 32a of the middle plate 32 does not serve as the center of swing of the middle plate 32, and regulates the position of the middle plate 2 in the front-rear direction.

In the above structure, the sheet material S
When the loading amount of 1 is large, as shown in FIG. 9, the top of the cam surface 37a of the support member 37 contacts the bottom surface of the intermediate plate 32 and serves as the center of swing of the intermediate plate 32. At this time, since the center of swing of the middle plate 32 is located at a position close to the center of gravity of the middle plate 32 and the sheet material S1, even if the stacking amount of the sheet material S1 is large, the change in moment due to the density difference of the sheet material S1 is small. . Further, when the sheet is fed and the stacking amount of the sheet material S1 is reduced, the center of swing of the intermediate plate 32 becomes the cam surface 37a of the support member 37.
Move up in the direction of arrow A2. At this time, the swing center of the intermediate plate 32 moves in the direction of arrow A2, and the intermediate plate 32 and the sheet material S1
Although the sheet material S1 moves in a direction away from the center of gravity, the stacking amount of the sheet material S1 decreases, and thus the influence of the density difference of the sheet material S1 on the sheet feeding pressure is reduced.

Here, an example of the sheet feeding pressure of the sheet feeding cassette having the configuration shown in this embodiment will be shown. As shown in FIG. 9, the middle plate 32
The distance l ₁ from the rocking shaft 32a to the paper feed roller 5 is 28
0 mm, from the swing shaft 32a of the middle plate 32 to the middle plate 3 of the spring 33.
The distance l 2 to the pressurizing position to ₂ is 280 mm, the middle plate 32
Length (distance from the rear end of the middle plate 32 to the tip of the separation claw 6)
l ₃ is 280 mm, the length of the sheet material S1 (rear end regulation plate 4
From the separation claw 6 the distance to the tip) l ₄ is 280 mm, the support member 37 of the cam surface 37a the intermediate plate spring 33 side end surface of the 32
To the swing axis 32a of x = 120 mm, and the spring 3
3 is 600 g when fully loaded and 640 g when lightly loaded, the middle plate 2 is pressed to have a constant spring constant, and the paper feeding pressure is calculated. The difference in sheet feeding pressure between the sheet material A and the sheet material B is 75 g, and, as in the first embodiment, the middle plate 2 swings at the position of the sheet feeding downstream end surface of the support member 7. With respect to a cassette having a center, the height of the cassette tray 1 is small, and the difference between the angles formed by the sheet material S1 and the separation claws 6 in a fully loaded state and a small loaded state is kept small, and the sheet material is It is possible to reduce variations in the sheet feeding pressure due to the difference in density of S1 and prevent defective sheet feeding and double feeding.

Further, as in the first embodiment, the supporting member A,
It is possible to adjust the sheet feeding pressure by changing parameters such as the pressing force of the spring 33.

Other structures and operations are the same as those of the first embodiment described above, and therefore, the same components are designated by the same reference numerals and their description is omitted.

In the above first, second and third embodiments, the case where the change in the sheet feeding pressure due to the difference in the density of the sheet material S1 is reduced has been described as an example, but the size of the sheet material is changed. It is also applicable in the case.

[0059]

According to the present invention having the above-mentioned structure and operation, the sheet feeding pressure of the sheet material which abuts the sheet material separating means is changed by changing the position of the supporting member for supporting the sheet material. It is possible to apply a sufficient sheet feeding pressure to the sheet material, and prevent defective sheet feeding and double feeding.

Further, the position for supporting the sheet material of the supporting member is moved according to the stacking amount of the sheet material, the change of the sheet feeding pressure is suppressed, and the stable sheet feeding pressure can be obtained.

Further, the position for supporting the sheet material holding means of the supporting member is moved in the direction in which the inclination angle of the sheet material holding means becomes smaller in accordance with the stacking amount of the sheet material holding means, whereby the sheet material sheet separating means is moved. The change in the contact angle between the sheet and the sheet becomes small, and stable sheet separation can be performed.

By providing a plurality of supporting members on the path moved in the direction in which the change of the sheet feeding pressure is reduced in accordance with the stacking amount of the sheet material, the supporting member abutting in correspondence with the stacking amount of the sheet material is provided. By changing the member, it is possible to suppress a change in the sheet feeding pressure of the sheet material and obtain a more stable sheet feeding pressure.

By providing this sheet feeding device in the sheet feeding cassette, the swing center of the sheet material holding means for mounting the sheet material is moved in correspondence with the stacking amount of the sheet material, and the sheet is fed by the density difference of the sheet material. It is possible to reduce variations in paper pressure, and by reducing the swing angle of the sheet material holding means,
The height of the cassette tray is reduced and the difference in the angle between the sheet material and the sheet material separating means at the time of full loading and low loading is reduced to prevent the occurrence of defective feeding and double feeding. It is possible to obtain a paper feed cassette.

Further, by providing the image forming apparatus with the above-mentioned sheet feeding cassette, an image forming apparatus with few sheet feeding defects can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view of a paper feed cassette according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional explanatory view of a paper feed cassette according to the first embodiment of the present invention.

FIG. 3 is a diagram of a sheet feeding pressure of a sheet feeding cassette according to the first embodiment of the present invention.

FIG. 4 is a cross-sectional explanatory view of a paper feed cassette showing a comparison between the first embodiment of the present invention and a conventional example.

FIG. 5 is a cross-sectional explanatory view of a paper feed cassette according to a second embodiment of the present invention.

FIG. 6 is a cross-sectional explanatory view of a paper feed cassette according to a second embodiment of the present invention.

FIG. 7 is a cross-sectional explanatory view of a paper feed cassette according to a second embodiment of the present invention.

FIG. 8 is a diagram of a sheet feeding pressure of a sheet feeding cassette according to a second embodiment of the present invention.

FIG. 9 is a cross-sectional explanatory view of a paper feed cassette according to a third embodiment of the present invention.

FIG. 10 is a cross-sectional explanatory view of a paper feed cassette according to a third embodiment of the present invention.

FIG. 11 is a diagram of a sheet feeding pressure of a sheet feeding cassette according to a third embodiment of the present invention.

FIG. 12 is an explanatory diagram showing a schematic configuration of an image forming apparatus.

FIG. 13 is a cross-sectional explanatory view of a conventional paper feed cassette.

FIG. 14 is a cross-sectional explanatory view of a conventional paper feed cassette.

FIG. 15 is a diagram of a sheet feeding pressure of a conventional sheet feeding cassette.

[Explanation of symbols]

 1 cassette tray 2,22,32, middle plate 3,23,33 spring 4 rear end regulation plate 5 paper feed roller 6 separation claw 7,27,37 support member 8,28 support member

Claims (6)

[Claims] 1. A sheet material holding means capable of stacking a plurality of sheet materials, a supporting member for swingably supporting the sheet material holding means, and the supporting member supporting the sheet material holding means. And a biasing means for biasing one end of the sheet material holding means to bring the placed sheet material into contact with the sheet material separating means and to apply a sheet feeding pressure. In the sheet feeding device, the position of the supporting member that supports the sheet material holding unit moves. 2. The position for supporting the sheet material holding means of the support member is moved in a direction to reduce a change in the sheet feeding pressure in accordance with the stacking amount of the sheet material. Paper feeder. 3. The position of the supporting member for supporting the sheet material holding means is moved in a direction in which the inclination angle of the sheet material holding means decreases in accordance with the stacking amount of the sheet material holding means. Item 3. The paper feeding device according to item 1 or 2. 4. A plurality of the support members are provided on a path moved in a direction to reduce a change of a sheet feeding pressure corresponding to a stack amount of the sheet material, and a sheet material holding member is provided when the stack amount of the sheet material changes. The sheet feeding device according to claim 1, wherein a supporting member that supports the means is replaced. 5. The sheet feeding device according to claim 1, wherein the sheet feeding cassette is provided in a sheet feeding cassette. 6. A sheet feeding device according to claim 1, 2, 3, 4 or 5, and image forming means for forming an image on a sheet material fed from the sheet feeding device. An image forming apparatus having.