JPH07215515A - Sheet feeding apparatus and image forming apparatus - Google Patents

Abstract

(57) [Abstract] [Purpose] When the sheet cassette is pulled out from the apparatus main body, the sheet feeding pressure and the separation pressure are released at the sheet feeding position so that the sheets in the sheet cassette are not adversely affected. [Structure] By pulling the handle 20, the link member 9 moves in the F'direction to separate the pad 16a from the paper feed roller 18 to release the separation pressure, and further, the middle arm 12 is rotated to move the inside. Copy paper 2 and paper feed roller 1 stacked on plate 4.
8 and are separated from each other to release the paper feeding pressure. As a result, each pressure can be released at the sheet feeding position of the cassette body 1, so that the copy sheet 2 does not remain in the apparatus body or the copy sheet 2 is not damaged.

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 such as a printer or a copying machine.

[0002]

2. Description of the Related Art Conventionally, there is a sheet feeding apparatus such as a copying machine as described in Japanese Utility Model Laid-Open No. 62-157726, which will be briefly described. The bottom plate (paper stacking table) that is swingably provided on the bottom plate part of the paper feed cassette or the main body of the apparatus is rocked upward, and the paper placed on the upper surface is pushed up and pressed toward the paper feed roller. Is configured to. A swingable member is provided at the handle portion of the paper feed cassette, and the operation of the swing member provided on the cassette pedestal can be controlled via the protrusion of the swing member. A cam member is provided on the side surface of the paper feed cassette to control the member for pushing up the paper, and a tongue for pushing up the paper and a separating member (sheet (Separating member) and the separating member) are controlled via the interlocking member.

When the paper feed cassette is pulled out, the oscillating member is swung to lower the tongue through the interlocking member to release the pressing of the paper.

[0004]

However, in the above-mentioned conventional example, the bottom plate on which the sheet is placed is swung downward through the member provided swingably on the handle portion of the sheet feeding cassette to feed the sheet. When pulling out the paper cassette,
Since the separating member acts so as to release the pressing of the sheet, the possibility that the separating member remains pressed against the sheet at the beginning of the movement of the sheet feeding cassette and the sheet conveying direction of the sheet feeding cassette If the vertical sheet position (abbreviated as lateral registration) is adjusted, the timing for releasing the pressing of the separating member on the paper changes, so the pressing on the paper is completely released when the cassette moves. Instead of pulling out the paper 2
When the separating member 16 remains at the position of the separating member 16,
The paper remains sandwiched between the paper feed roller 18 and
Even if the sheet 2 remains in the apparatus without coming out of the apparatus at the same time as the sheet feeding cassette, or if it comes out, there is a problem that the leading edge of the sheet becomes more unusable.

The present invention has been made in view of the above problems, and when the sheet cassette is pulled out from the main body of the apparatus,
An object of the present invention is to prevent the sheet in the sheet cassette from being adversely affected by releasing the sheet feeding pressure and the separation pressure at the sheet feeding position.

[0006]

According to the present invention, there is provided a sheet cassette which has an intermediate plate which supports a sheet and which can be moved up and down, and which is detachably provided at a feeding position of the apparatus main body for feeding the sheet. A sheet feeding means provided in the apparatus main body for feeding out a sheet supported by the sheet cassette; and a sheet provided in the apparatus main body, which raises the middle plate of the sheet cassette and is supported by the middle plate. A lift means for bringing the sheet feeding means into contact with the sheet feeding means by a sheet feeding pressure by an elastic force of a predetermined elastic body, and a sheet for separating the sheets fed by the sheet feeding means one by one by a predetermined separation pressure. The sheet cassette is operated by the separating means, the switching means for switching the separating means between the releasing state and the generating state of the separating pressure, and the operating means provided in the sheet cassette, and the sheet cassette is operated by the intermediate plate. Characterized by comprising a pressure releasing means for releasing the separation pressure of the sheet feeding pressure and the separating means between the support has been that sheet and the sheet feeding means.

According to the present invention, when the sheet cassette is mounted at the feeding position of the apparatus main body, the lift means raises the intermediate plate to press the sheet against the sheet feeding means, and It is characterized in that the switching means is provided with a pressurizing means for generating a separation pressure in the released state of the separating means.

According to the present invention, the separating means comprises the sheet feeding means and a pad which presses against the sheet feeding means by an elastic member to generate a predetermined separating pressure, and the pressing means comprises the sheet. It is characterized in that it has a moving member for moving the pad closer to a position where it is in pressure contact with the sheet feeding means in accordance with the mounting of the cassette on the apparatus main body.

According to the present invention, the separating means comprises a feed roller arranged on the downstream side of the sheet feeding means and a reversing roller for pressing the feed roller with an elastic member to generate a predetermined separating pressure. The pressurizing unit includes a moving member for moving the reverse rotation roller closer to a position where the reverse rotation roller is pressed against the feed roller in accordance with mounting of the sheet cassette on the apparatus main body.

According to the present invention, the pressurizing means has a link member for connecting the lift means and the switching means and moving in one direction to generate a sheet feeding pressure and a separation pressure. The pressure releasing means is characterized in that the paper feeding pressure and the separation pressure are released by operating the operating means to move the link member in the other direction.

According to the present invention, the lift means has a lever member which is rotated by an elastic force of an elastic member, and an arm member which is connected to the lever member and abuts against the intermediate plate to lift the link member. Is connected to the lever member and moved by the rotation of the lever member, and the movement of the lever member causes the switching means to operate via the link member.

According to the present invention, the elastic member generates an elastic force when the sheet cassette is attached to the apparatus main body,
An elastic force is not generated when the sheet cassette is pulled out from the apparatus main body.

According to the present invention, the operating means is a rotatable handle member provided on the sheet cassette, and the pressure releasing means performs the pressure releasing operation by rotating the handle member. And

According to the present invention, the sheet cassette is set so that the mounting direction of the sheet cassette to the apparatus main body is orthogonal to the sheet feeding direction, and the sheet cassette has an adjusting means for adjusting the sheet feeding position. However, the pressure releasing means releases the sheet feeding pressure and the separation pressure at the adjusted position of the sheet cassette.

According to the present invention, the sheet cassette is set such that the mounting direction of the sheet cassette is orthogonal to the sheet feeding direction, and the sheet cassette has an adjusting means for adjusting the sheet feeding position. However, the pressurizing means generates the sheet feeding pressure and the separation pressure at the adjusted position of the sheet cassette.

[0016]

When the sheet cassette is pulled out from the main body of the apparatus, the pressure releasing means releases the sheet feeding pressure and the separating pressure at the sheet feeding position of the sheet cassette. Therefore, the sheet cassette moves while the sheet is sandwiched by the separating means. Since the sheet does not move, the sheet does not remain on the apparatus main body side or the sheet is not wrinkled.

Further, this structure can be applied to a separating means using a pad and a separating means using a reverse roller.

When a link member is used as the pressurizing means, the paper feeding pressure and the separation pressure can be generated by the pressurizing means when the link member is moved in one direction, and the pressure releasing means moved in the other direction. The paper feed pressure and separation pressure can be released by.

Further, by making the operating means a handle used when pulling out the sheet cassette, the paper feeding pressure and the separation pressure can be released only by rotating the handle.

When the feeding pressure and the separation pressure are increased or released according to the adjustment position of the adjusting means for adjusting the feeding position, the feeding pressure and the separation pressure are reliably adjusted at the adjusted feeding position. Pressurization or release can be performed, and the adverse effect on the seat can be more reliably prevented.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a perspective view showing a first embodiment of the present invention, in which reference numeral 1 designates a cassette body on which copy sheets 2 are stacked, and side regulating plates 3 are provided on both sides of the copy sheet 2 in the sheet feeding direction. Are regulated. Reference numeral 4 denotes an intermediate plate on which the copy paper 2 is placed, and a fulcrum portion 4-
It is rotatably supported around a. Reference numeral 5 denotes a front lever, one end of which is fixed to the front lever shaft 6 at a portion 5a, and the front arm 7 is fixed to the other end thereof.
It is rotatably supported by the portion 8a.

A dowel 9a provided at one end of the link member 9 is fitted in the elongated hole 5b, and a dowel 9b provided at the other end is fitted in the elongated hole 10b of the middle lever 10 so that the front lever 6 is fitted.
The movement of the link member 9 is controlled by the middle lever 10.

The middle lever 10 is fixed to one end of a middle lever shaft 11 at a portion 10a, and a middle arm 12 is fixed to the other end of the middle lever shaft 11, and the middle lever shaft 11 is a portion 8b of the body side plate 8. It is supported in a rotatable state. One end of the spring 13 is hooked on the 10c portion of the middle lever 10,
The other end of the spring 13 is hooked on the portion 14b of the rear lever 14,
The rear lever 14 has a hole 14a that fits into the dowel 8e of the body side plate 8 and is rotatably supported around the hole 14a. Further, the rear lever 14 has a dowel 14c which penetrates the hole 8c of the main body side plate 8 and contacts the cam surface 1a provided on the side surface of the cassette main body 1 side.

The body side plate 8 has a hole 8d for fitting with the pad arm 16, and the pad arm 16 has a hole 8d.
A dowel 16b that fits with the pad arm 16 is provided. The pad holder 15 is rotatably supported around the dowel 16b, and is fitted to the pad arm 16 so that the pad holder 15 comes into contact with the convex portion 9c provided at a part of the link member 9. By being connected, the rotation of the pad arm 16 is restricted.

The pad holder 15 is provided with a spring 15a (shown in FIG. 3) for bringing the pad 16a into contact with the paper feed roller 18 to generate a predetermined separation pressure. Then, the convex portion 9c of the link member 9 pushes up the pad holder 15 to move the pad 16 through the spring 15a.
a is pressed against the paper feed roller 18.

As shown in FIGS. 2 and 3, the pad holder 15 is provided with a cam follower 16c, and the link member 9 is provided with a cam member 9d which engages with the cam follower 16c. . When the link member 9 moves in the F'direction, the slope of the cam member 9d engages with the cam follower 16c, and the pad arm 16
Is rotated in a direction in which the pad 16a is separated from the paper feed roller 18. With this configuration, the separation pressure can be reliably released, and the spring force of the spring 15a can be easily set, so that the degree of freedom in design is increased.

Next, the operation of the above structure will be described in order. In FIG. 4, the cassette body 1 is set in the direction of arrow A along a guide rail provided on the body (not shown). At this time, the cam 1 provided on the side surface of the cassette body 1
The surface a and the dowel 14c of the rear lever 14 contact each other, and the rear lever 14 rotates in the direction of arrow B around the hole 14a in conjunction with the movement of the cassette body 1. The series of movements at this time are shown in FIGS. 5A to 5D, which will be described.

FIG. 5 (a) is a view showing a state in which the cassette body 1 moves in the direction of arrow A. At this time, the dowel 14c of the rear lever 14 and the cam surface 1a are not yet in contact with each other. A handle 20 having a dowel 20a fitted in the hole 1b is rotatably supported on the cassette body 1 about the dowel 20a.
The handle 20 includes a protrusion 20b, a protrusion 20c, and a handle 20.
have d. The protrusion 20c is pulled in the direction of arrow C by the spring 21.

FIG. 5 (b) is a view showing a state where the cassette body 1 moves in the direction of arrow A and the cam surface 1a and the dowel 14c of the rear lever 14 are in contact with each other. Rotate around the dowel 8e in the direction. At this time, the middle lever 10 is given a force to rotate the 10a portion in the direction of the central arrow D through the spring 13 that is not applied with tension until then on the rear lever 14. However, the protrusion 20b of the handle 20 is pressed by the lateral registration block 22, and the handle 20 rotates in the direction of arrow C'against the spring force of the spring 21, whereby the protrusion 20c.
Restricts the rotation of the front arm 7 in the arrow E direction, the middle lever 10 cannot rotate in the arrow D direction, and the spring 13
Is charged.

FIG. 5 (c) is a view showing a state where the cassette body 1 is set at a predetermined position, and the convex portion 1c provided on one body of the cassette body 1 has the regulation surface 22a of the lateral registration block 22.
And the convex portion 20b of the handle 20 is in contact with the horizontal registration block 2
2, the dowel 20a is rotated about the dowel 20a by the spring force of the spring 21 in the direction of the arrow C, and the lateral registration block 22 is sandwiched. Then, the spring force of the spring 13 charged in the forearm 7 held by the convex portion 20c causes the arrow E to move.
The front lever 5 by the spring force of the same spring 13
Rotates in the direction of arrow E, and the middle lever 10 and the middle arm 12 rotate in the direction of arrow D, and the link member 9 moves in the direction of arrow F. By this series of movements, the link member 9 pushes up the pad holder 15 with the convex portion 9c and the pad arm 16
The pad 16a provided on the upper arm is brought into contact with the paper feed roller 18 attached to the drive shaft 19 rotatably supported by the apparatus main body (not shown).
By rotating in the direction of, the intermediate plate 4 shown in FIG. 4 is pushed up, and the copy paper 2 stacked on it is brought into contact with the paper feed roller 18.

FIG. 5D is a view showing the movement when the cassette body 1 is pulled out in the direction of the arrow A ', and the convex portion 2 of the handle 20 is shown.
By gripping 0d and rotating it in the direction of arrow C'against the spring force of the spring 21, the convex portion 20b is moved to the lateral registration block 2
By moving the lower surface of 2 to a movable position, the cassette body 1 becomes movable in the direction of arrow A ', and the convex portion 20c resists the front arm 7 against the spring force of the spring 13 and moves in the direction of arrow E'. Since it is rotated, the rear lever 5 rotates in the arrow E'direction, and the middle lever 10 and the middle arm 12 rotate in the arrow D'direction. Along with that, the link member 9 is moved to the arrow F ′.
By moving in the direction, the pad arm 16 that is in contact with the paper feed roller 18 moves in the direction of arrow G '.

FIG. 6 is a view showing the relationship between the lateral registration block 22 and the cassette body 1. The copy paper 2 is fed in the direction perpendicular to the surface and from the back to the front. At this time, the lateral registration block 22 is a mechanism for correcting the deviation amount from the reference in the direction I orthogonal to the feeding direction of the copy paper 2 stacked on the middle plate 4 of the cassette body 1. Is provided on the main body 8 ′ so as to be movable in the I direction via the ball screw member 23. By rotating the member 23 from the arrow H side by the operator, the worker moves in the I direction so that the proper image position is obtained. Determine the position in the I direction.

At this time, the cassette body 1 is moved in the direction A (the direction in which the cassette body 1 is inserted), and the convex portion 1 of the cassette body 1
The sheet feeding standard of the apparatus body and the sheet feeding standard of the cassette body 1 can be matched by abutting a with the regulation surface 22a of the lateral registration block 22.

Further, at this time, in order not to change the charging force of the spring of the spring 13 of FIG. 1 by changing the set position of the cassette main body 1 by the adjustment of the lateral registration block 22, the side surface of the cassette main body 1 shown in FIG. Cam surface 1 as shown in
a is provided, and when the cassette body 1 is moved in the direction of arrow A, the rear lever 14 is rotated in the direction of arrow B around the dowel 8e with the dowel 14c contacting the cam surface 1a.
It is pushed up to the flat surface 1c of width l. Then, even if the cassette moves further in the direction of arrow A, the spring 1
No more charging the spring force of 3.

If the adjustment amount of the flat surface 1c having the width 1 and the lateral registration block 22 of FIG. 6 is l ', then l>l'.

Further, the dowel 14c of the rear lever 14 shown in FIG. 7 is designed to be within the width l even when the lateral registration block 22 is adjusted to either end in the I direction of FIG.

As described above, in this embodiment, the cassette body 1 does not damage the copy paper 2 even if the copy paper 2 that has been double-fed at the time of feeding the copy paper 2 projects to the separating portion.
Can be withdrawn. Further, in this embodiment, when the cassette body 1 is inserted, the handle 20 is lowered by the lateral registration block 22 so that the front arm 7 does not move up even if the handle is not operated. Since the plate 4 is prevented from being pressed toward the paper feed roller 18, the copy paper 2 touches the paper feed roller 18 while the cassette body 1 is moving in the direction A, and the cassette body 1 is further pushed. It is possible to prevent the copy paper 2 from sometimes wrinkling.

Further, in this embodiment, since the middle arm 12 that pressurizes the middle plate 4 is arranged so as to fall in the direction in which the cassette body 1 escapes, damage to the handle 20 or the like causes
Even if the pressurizing mechanism is not released, when the cassette body 1 is pulled out, the bottom of the cassette body 1 pushes down the middle arm 12, and the pad 16 also goes down in conjunction with it, so the trouble is minimized by the same effect as usual. To be Moreover, in this embodiment, even if the lateral registration block 22 is moved in the I direction by adjusting the image position, the pulling amount of the spring 13 is determined by the cam as shown in FIG. ) Is applied and the paper feed pressure can be kept constant.

Further, since the tension is not generated in the spring 13 unless the rear lever 14 is at the back and the cassette body 1 is inserted, the cassette body 1 is pulled out to the outside of the apparatus and even if the user puts his / her hand into the cassette insertion port, Since there is no member that moves due to, etc., it is possible to prevent damage and the like without causing unnecessary operation. In contrast to this embodiment, when there is a sufficient sheet feeding pressure at the time of sheet feeding, as shown in FIG. 8, the cassette body 1 is not provided with a cam portion, and the 1a portion and the rear lever 14 'move in the arrow direction. Even if the spring 13 is extended and tension is applied only by sliding, the same effect can be obtained. In addition,
Although the cassette body 1 and the rear lever 14 'are separated from each other in the figure, the rear lever 14' is actually fitted in the groove portion of the cassette body 1.

FIG. 9 shows the second embodiment, which will be described. When the hooking portion 20b of the handle 20 engages with a lateral registration block (not shown) and moves up, the front arm 7'is moved up in the direction of arrow N by the force of a spring (not shown) attached to the handle. Thereby, the front lever 5 '
Rotates around the rotation center 7b in the M direction, and the link member 9'moves in the L direction to press the separating member 16 and the intermediate plate 4. This pressurizing mechanism is the same as in the first embodiment. Further, when the grip 20 is gripped, 20b is lowered and the front arm 7'separates the intermediate plate 4 and the pad 16a from the paper feed roller 18 by an elastic member such as a spring (not shown) that generates a force on the rotation center 7b in the arrow K direction. Left is released. With such a configuration, the same effect as that of the first embodiment can be obtained.

Further, even if there is no elastic member provided at the rotation center 7b, the pressure can be released by the weight of the intermediate plate 4 or the like. In this case, the number of parts can be reduced and the cost can be reduced.

Further, a third embodiment is shown in FIGS. In FIG. 10, when the cassette body 1 is inserted in the direction A, the slide piece 155 abuts the protrusion 1e against the overhanging portion 1d as shown in FIGS.
Move in the direction. As a result, as shown in FIG. 10, the pressing piece 153 presses the pressing arm 151 with the spring 152.

As a result, the shaft 150 rotates in the direction of arrow R, and the pressure plate 112 presses the intermediate plate 104 against the paper feed roller 18. Further, by moving in the direction of the pressure cam 154A ′, the pad 116 is pressed against the paper feed roller 18 via the cam 115. Even at this time, the horizontal registration block (not shown) is the convex portion 120a of the handle 120 of the cassette body 1,
Since the cassette body 1 is rotated in the S direction so that it does not rise until it is inserted into the predetermined position, the front arm 10
The shaft 150 is rotated in the P direction via 7 to lower the intermediate plate 104. Further, the pad 116 has a shaft 15 as shown in FIG.
The claw 116a is hooked by the arm 159 attached to No. 0 and at the same time separated from the paper feed roller 18. Therefore, even when the cassette body 1 is pulled out, the handle 20
By grasping, the pad 116 and the intermediate plate 104 can be released, and then the cassette body 1 can be pulled out. In order to ensure that the pressure cam 154 comes to the release position when the cassette is taken out, the cassette has the protrusion 1e, and the pressure cam 154 is moved in the direction C of FIG. 10 by the stopper (not shown). When C cannot move in the C direction, the slide piece 155 retracts against the spring 156, and only the cassette moves in the C direction, and the cassette can be taken out from the main body. At this time, since the pressure cam 154 has a position where the cam portion moves and does not press the pressure arm 151 and the cam 115, the middle plate 104 and the pad 106 remain separated from the paper feed roller 18 after the cassette body 1 is pulled out. Becomes

Even with this structure, the same effect as that of the first embodiment can be obtained.

Next, a schematic structure of a copying machine equipped with the sheet feeding apparatus of the present invention will be described. In FIG. 13, 10
Reference numeral 1 denotes an original table glass for placing an original, on which an original to be copied is placed. Reference numeral 102 denotes an exposure device which moves in the direction of arrow X and scans the entire surface of the original while irradiating the original placed on the original table glass 101 with light.

The reflected light obtained by illuminating the original with the exposure device 102 is the first mirror group 103.
a, the zoom lens 104, and the second mirror group 103b
An image is formed on the photosensitive drum 105 via the, and an electrostatic latent image is formed.

The photosensitive drum 105 is provided in the process cartridge 106 equipped with a plurality of process means for contributing to image formation around the photosensitive drum 105.
Around the circumference of 5, a charging means, a developing means, a cleaning means, etc. are arranged. The electrostatic latent image formed on the photosensitive drum 105 is developed by the developing means and visualized.

Reference numeral 1 denotes a cassette body for stacking and storing copy paper 2, which is detachably mounted on the bottom of the apparatus body.
When the cassette body 1 is mounted on the apparatus body, the middle arm 12 on the apparatus body side rotates in conjunction with the movement of the cassette body 1 to push up the middle plate 4 and copy papers stacked on the middle plate 4. 2 is pressed against the paper feed roller 18 so that a frictional force is generated between the two. Reference numeral 16a denotes a pad, which is pressed by the pad spring 15a and is in pressure contact with the paper feed roller 18.

When the paper feed roller 18 rotates, the uppermost copy paper 2 is fed, and the paper feed roller 18 and the pad 16 are fed.
When passing between a and a, they are separated and fed one by one. Then, it is conveyed through a reverse conveyance path formed between the paper feed roller 18 and the reverse guide 111, and then passes through the pre-registration guide 112 and is guided to the registration roller pair 113 which is temporarily stopped. The registration roller pair 113 synchronizes with the developed image formed on the photosensitive drum 105 and conveys the copy paper 2 to the transfer portion.

A transfer roller 114 is in pressure contact with the photosensitive drum 105. The registration roller pair 11
The copy paper 2 conveyed by 3 is the photosensitive drum 10 described above.
5 and the transfer roller 114, the developed image is transferred. The copy paper 2 after the image transfer is carried by the carrying device 115, and when passing through the fixing device 116, heat and pressure are applied to fix the transferred image. Then, the copy paper 2 after the image fixing is discharged to the outside of the apparatus by the discharge roller pair 117.

The present invention is not limited to the above embodiment. For example, although the pad is used as the separating means in the above-described embodiment, a separation method (so-called retard roller method) including a feed roller arranged on the downstream side of the paper feed roller and a reverse roller pressed against the feed roller. The present invention may be applied to a sheet feeding device using the. In this case, instead of the pad of the above embodiment, the reverse rotation roller is separated from the feed roller to release the separation pressure.

In the above embodiment, the sheet feeding apparatus of the present invention is used in an electrophotographic copying machine, but a laser beam printer, a facsimile machine, an ink jet printer, or any other image forming apparatus. It may be applied to the device.

[0053]

As described in detail above, the present invention is
When the sheet cassette is pulled out from the main body of the apparatus, the pressure releasing means releases the sheet feeding pressure and the separation pressure at the sheet feeding position of the sheet cassette, so that the sheet cassette may move while the sheet is sandwiched by the separating means. The sheet does not disappear, the sheet remains on the main body of the apparatus, and the sheet does not fail to be fed, and the sheet is not wrinkled or damaged. Therefore, the reliability of the sheet feeding device can be improved.

This structure has high versatility because it can be applied to a separating means using a pad and a separating means using a reverse roller.

If the lift means and the pressure releasing means are simultaneously operated by using the link member, the structure can be simplified and the reliability of the apparatus can be further enhanced.

[Brief description of drawings]

FIG. 1 is a perspective view showing a main part of a sheet feeding device according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing the configuration of the separating means shown in FIG.

FIG. 3 is a diagram showing the operation of the separating means shown in FIG.

FIG. 4 is a view showing the operation of the mechanism shown in FIG.

FIG. 5 is a view showing the operation of the mechanism shown in FIG.

FIG. 6 is a diagram showing an adjusting mechanism for adjusting a sheet feeding position of a sheet cassette.

7 is a diagram showing a cam surface of the sheet cassette shown in FIG.

FIG. 8 is a diagram showing another embodiment of the cam surface of the sheet cassette.

FIG. 9 is a perspective view showing a main part of a sheet feeding device according to a second embodiment of the present invention.

FIG. 10 is a perspective view showing a main part of a sheet feeding device according to a third embodiment of the present invention.

FIG. 11 is a diagram showing a cam surface of a sheet cassette provided in the third embodiment.

FIG. 12 is a view showing a separating pressure releasing means of the third embodiment.

FIG. 13 is a vertical cross-sectional view showing an example of an image forming apparatus including the sheet feeding device of the present invention.

FIG. 14 is a perspective view showing a state in which a sheet is sandwiched by separating means in a conventional device.

[Explanation of symbols]

 1 Cassette Body (Sheet Cassette) 2 Copy Paper (Sheet) 4 Middle Plate 9 Link Member (Pressure Means) 9c Convex Part (Switching Means) 10 Middle Lever (Lift Means) 12 Middle Arm (Lift Means) 13 Spring (Lift Means) ) 15 pad holder 16a pad 18 paper feed roller (sheet feeding means) 20 grip (operating means) 22 lateral registration block (adjusting means)

Claims (11)

[Claims] 1. A sheet cassette, which has an intermediate plate that supports a sheet and can be moved up and down, and is detachably provided at a feeding position for feeding a sheet of an apparatus main body; A sheet feeding unit that feeds a sheet supported by the sheet cassette, and a sheet that is provided in the main body of the apparatus and raises a middle plate of the sheet cassette to elastically move the sheet supported by the middle plate to the sheet feeding unit. Lifting means for bringing the sheets into contact with each other at a predetermined feeding pressure by elastic force of the body, separating means for separating the sheets sent by the sheet feeding means one by one by a predetermined separating pressure, and the separating means. Switching means for switching between a release state and a generation state of the separation pressure, and an operation means provided in the sheet cassette, when the sheet cassette is in the feeding position, A sheet feeding apparatus is characterized in that and a pressure releasing means for releasing the separation pressure of the sheet feeding pressure and the separating means between the seat which is supported on the plate and the sheet feeding means. 2. When the sheet cassette is mounted at the feeding position of the apparatus main body, the lift means raises the intermediate plate to press the sheet against the sheet feeding means, and the switching means. 2. The sheet feeding apparatus according to claim 1, further comprising a pressurizing unit for generating a separating pressure in a released state of the separating unit. 3. The separating means comprises the sheet feeding means and a pad which presses against the sheet feeding means by an elastic member to generate a predetermined separating pressure, and the pressing means is provided for the sheet cassette. The sheet feeding device according to claim 2, further comprising a moving member for moving the pad closer to a position where the pad is brought into pressure contact with the sheet feeding means according to attachment to the apparatus main body. 4. The separating means comprises a feed roller arranged on the downstream side of the sheet feeding means and a reversing roller for pressing the feed roller with an elastic member to generate a predetermined separating pressure. 3. The sheet feeding apparatus according to claim 2, wherein the pressure unit includes a moving member for moving the reverse rotation roller closer to a position in which the reverse rotation roller is pressed against the feed roller according to mounting of the sheet cassette on the apparatus main body. Sending device. 5. The pressurizing means includes a link member that connects the lift means and the switching means and moves in one direction to generate a paper feed pressure and a separation pressure, and the pressure release means. 5. The sheet according to claim 2, wherein the means releases the paper feeding pressure and the separation pressure by operating the operating means to move the link member in the other direction. Feeding device. 6. The lift means includes a lever member that is rotated by the elastic force of an elastic member, and an arm member that is connected to the lever member and that abuts against the intermediate plate and lifts the link member, and the link member includes the arm member. The sheet feeding device according to claim 5, wherein the sheet feeding device is connected to the lever member and moves by the rotation of the lever member, and the switching unit operates via the link member by the movement of the lever member. 7. The elastic member generates an elastic force when the sheet cassette is attached to the apparatus body, and does not generate an elastic force when the sheet cassette is pulled out from the apparatus body. Item 7. The sheet feeding device according to item 6. 8. The operating means is a rotatable handle member provided in the sheet cassette, and the pressure releasing operation by the pressure releasing means is performed by rotating the handle member. The sheet feeding device according to claim 1. 9. The sheet cassette is set such that the mounting direction of the sheet cassette to the apparatus main body is orthogonal to the sheet feeding direction, and has an adjusting means for adjusting the sheet feeding position of the sheet cassette. 9. The sheet feeding apparatus according to claim 8, wherein the pressure releasing means releases the sheet feeding pressure and the separating pressure at the adjusted position of the sheet cassette. 10. The sheet cassette is set such that the mounting direction of the sheet cassette to the apparatus main body is orthogonal to the sheet feeding direction, and has adjusting means for adjusting the sheet feeding position of the sheet cassette, 9. The sheet feeding apparatus according to claim 8, wherein the pressurizing unit generates a sheet feeding pressure and a separation pressure at an adjusted position of the sheet cassette. 11. A sheet cassette, which has an intermediate plate that supports a sheet and can be raised and lowered, and is detachably provided at a feeding position for feeding a sheet of an apparatus main body, and provided on the apparatus main body, A sheet feeding unit that feeds out a sheet supported by the sheet cassette, and a sheet that is provided in the main body of the apparatus and raises an intermediate plate of the sheet cassette to support the sheet supported by the intermediate plate to the sheet feeding unit. Lifting means for bringing them into contact with each other at a sheet feeding pressure, separating means for separating the sheets sent out by the sheet feeding means one by one by a predetermined separating pressure, and the separating means for releasing the separating pressure. A switching means for switching to the generation state, and a sheet supported by the intermediate plate when the sheet cassette is in the feeding position by being operated by the operating means provided in the sheet cassette. Pressure releasing means for releasing the sheet feeding pressure between the sheet feeding means and the sheet feeding means and the separating pressure of the separating means, and an image forming means for forming an image on the sheet separated by the separating means. An image forming apparatus characterized by.