JP2002068487A - Paper feed cassette and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make paper feeding in good performance even in the condition that the number of paper sheets in the cassette has decreased. SOLUTION: This paper feed cassette comprises a cassette case, a sheet pushup plate which is supported swingably in the vertical direction so that the downstream end about the sheet feeding direction approaches and moves apart from a separator claw and is provided with an engagement hole in the upstream side about the sheet feeding direction and whereon paper sheets are placed in stack, a resilient member to give an upward directed resilient force to the pushup plate, and a sheet trailing edge guide which is arranged upright on the upper side of the upstream end in sheet feeding direction of the pushup plate and whose top is pivoted on the cassette case in such a way as swinging in the sheet feeding direction and bottom is engaged with the engagement hole in the plate so that the trailing edges of the sheets are held down, wherein the engagement hole in the plate is arranged so that the upstream edge of the engagement hole pushes a sheet trailing edge guide toward downstream when the pushup plate swings upward.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper cassette and an image forming apparatus provided with the paper cassette.

[0002]

2. Description of the Related Art An image forming apparatus such as a facsimile machine, a printer or a copying machine is provided with a paper feed cassette for stacking and storing recording papers made of cut sheets to be supplied to an image forming mechanism provided in an image forming apparatus main body. I have.

[0003] This paper feed cassette has a cassette case in which an upper surface is opened and a separation claw is formed at a downstream end of the open portion in the paper feed direction, and recording paper is stacked and accommodated therein.
It is arranged inside the cassette case and is supported swingably along the vertical direction so that the downstream end portion in the sheet feeding direction approaches and separates from the separation claw provided in the cassette case, and the sheet feeding direction. A sheet push-up plate on which an engagement hole is formed at an upstream end portion and on which recording papers stacked and housed in a cassette case are placed; and an elastic member for applying an upward elastic force to the sheet push-up plate; It is provided with.

That is, in this paper feed cassette, when recording papers are stacked on a paper push-up plate and accommodated in a cassette case, the elastic member pushes up the paper push-up plate so that the paper is stacked on the paper push-up plate. The uppermost layer of the recording paper is pressed by the separation claw of the cassette case to prevent the paper lifting plate from swinging upward. Then, the cassette case is inserted into the main body of the image forming apparatus, and the uppermost recording sheet is removed from the separation claw by the rotation of a paper feed roller provided in the main body of the image forming apparatus, and is fed out of the cassette case.

In this paper feed cassette, a paper rear end guide is provided inside the cassette case so that the upstream end (rear end) of the recording paper placed on the paper push-up plate in the paper feed direction is positioned upstream in the paper feed direction. As the paper push-up plate swings upward, the recording paper retreats to the upstream side in the paper feeding direction, and the downstream end (front end) of the recording paper in the paper feeding direction is moved to the cassette case. It has been practiced to prevent the separation claw (feed roller of the image forming apparatus main body) from coming off.

Conventionally, as a paper feed cassette provided with a paper rear end guide, Japanese Patent Application Laid-Open Nos.
329957 and JP-A-11-263448.

In the first paper feed cassette, a size regulating plate is provided on the cassette case behind the paper pushing plate, and the size regulating plate is provided with a recording paper placed on the paper pushing plate. A rear end regulating member that presses the end from the rear side is swingably supported in the paper feeding direction, and a spring force is applied to the rear end regulating member toward the downstream side in the paper feeding direction to form a paper rear end guide. In conjunction with the upward swinging of the rear end guide, the rear end regulating member is swung forward by a spring via a slide plate to push out the recording paper toward the front in the paper feeding direction and to maintain the position of the recording paper. Things.

The second paper feed cassette has a main member vertically penetrating through an opening formed in the paper push-up plate and having a lower end swingably supported in a paper feed direction on a bottom portion of the cassette case. The paper trailing edge guide is composed of an auxiliary member that is attached to the paper lifting plate at a right angle and that is slidably combined with the main member.The paper trailing edge guide is used regardless of the swing of the paper lifting plate. The front end of the recording paper is engaged with the separation claw while always being maintained at a right angle.

The third paper feed cassette moves the moving means in the front-rear direction by swinging the paper push-up plate, and the recording paper placed on the paper push-up plate by the paper rear end guide supported by the moving means. The restriction is intended to prevent the recording paper from coming off the separation means.

[0010]

However, the first paper feed cassette always applies a force to the rear end regulating member in the paper feed direction front by a spring to keep the rear of the recording paper placed on the paper push-up plate. Since the end is pressed, the entire recording paper placed on the paper lifting plate receives the spring force in a shared manner. For this reason, if the number of recording sheets on the sheet lifting plate decreases as the sheet feeding progresses, the recording sheet per sheet receives a large spring force, and as a result, the recording sheet is pushed forward. Collides with the paper feed roller to cause deflection. The bent recording paper P adversely affects image recording. The degree of occurrence of such a problem is more remarkable in a sheet cassette in which the number of recording sheets accommodated is larger.

The second paper feed cassette has a length in which the front end portion of the paper push-up plate and the separation claw of the cassette case vertically overlap with each other when the paper push-up plate swings upward from the horizontal position and tilts. As the number of recording papers placed on the paper lifting plate decreases and the paper lifting plate moves upward, the length of the front end of the recording paper In some cases, the sheet may be reduced and come off the separation claw, which may hinder the sheet feeding operation. The degree of occurrence of this inconvenience becomes more remarkable in a sheet cassette in which the number of recording sheets accommodated is larger.

The third paper cassette has the same problem as the second paper cassette.

The present invention provides a sheet feeding cassette capable of feeding well even when the number of sheets placed on the sheet lifting plate is reduced and the sheet lifting plate swings upward. The purpose is to:

Further, the present invention provides an image forming apparatus for detecting a sheet size using the sheet cassette.

[0015]

According to a first aspect of the present invention, there is provided a sheet cassette in which an upper surface is opened, and a separation claw is provided at a downstream end of the open portion in a sheet feeding direction, and sheets are stacked and accommodated therein. And a cassette case disposed inside the cassette case and supported so as to be vertically swingable such that a downstream end in the sheet feeding direction approaches and separates from a separation claw of the cassette case. At the same time, an engagement hole is formed at the upstream end portion in the paper feeding direction, and a paper push-up plate on which sheets stacked and accommodated in the cassette case are placed, and an upward elastic force is applied to the paper push-up plate. An elastic member to be added, and a lower end pivotally supported by the cassette case with an axial line extending along a direction intersecting the sheet feeding direction with an upper end standing vertically above the upstream end in the sheet feeding direction of the sheet lifting plate. Part is the paper push-up plate A sheet rear end guide which is engaged with the engagement hole and presses an upstream edge of a sheet placed on the sheet lifting plate in a paper feeding direction on an upstream side in the paper feeding direction; The engaging hole of the engaging hole is configured such that, when the sheet lifting plate swings upward, the upstream edge of the engaging hole in the sheet feeding direction pushes the sheet rear end guide toward the sheet feeding direction downstream to swing. It is characterized by being.

According to the configuration of the present invention, when the sheet push-up plate swings upward, the rear end of the engagement hole formed in the sheet push-up plate moves the sheet rear end guide to the downstream side in the sheet feeding direction. As the paper is pushed, the paper trailing end guide swings around the upper end pivot to the downstream side in the paper feeding direction, and pushes out the rear end of the paper placed on the paper lifting plate to move the paper downstream in the paper feeding direction. It can be moved to hold the front end of the paper at a position where it can be hooked on the separation claw provided on the cassette case. Therefore, even if the number of sheets to be placed decreases and the sheet push-up plate swings upward, the sheet can be satisfactorily fed without being detached from the separation claw. In addition, the paper trailing end guide swings to the downstream in the paper feeding direction at an angle corresponding to the swing angle to push and move the paper to the downstream in the paper feeding direction only when the paper lifting plate swings upward. When the paper needs to be hooked on the separation claw of the cassette case, it can be moved by a necessary amount and hooked on the separation claw of the cassette case. Accordingly, the paper rear end guide does not always apply a strong force to the paper downstream in the paper feeding direction unlike the case where the paper is constantly pressed by the spring force. Even if the number of papers to be loaded decreases and the paper lifting plate swings upward, the paper trailing edge guide does not force the paper with a strong force and press it against the paper feed roller to bend. The sheet feeding operation can be performed well.

According to a second aspect of the present invention, there is provided an image forming apparatus main body having a sheet feeding cassette loading section, an image forming mechanism provided in the image forming apparatus main body, and a sheet feeding cassette of the image forming apparatus main body. The paper cassette according to claim 1, wherein the paper cassette is loaded in the loading section so as to be able to be taken in and out in a direction orthogonal to the paper feeding direction, and the paper cassette is loaded in the paper cassette loading section. It is characterized in that a detection switch for detecting a paper size, which is sometimes operated by the rear end guide provided in the paper feed cassette, is provided.

According to the configuration of the present invention, the size of the paper accommodated in the paper cassette is easily detected by loading the paper cassette into the paper cassette loading section of the image forming apparatus main body, and the information is displayed as an image. It can be utilized for the operation of the forming apparatus.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a cross-sectional view schematically showing a vertical transport type image forming apparatus loaded with a sheet cassette of the present invention.

In FIG. 1, reference numeral 1 denotes an image forming apparatus main body, 2 denotes an image reading section provided on an upper portion of the image forming apparatus main body 1 for mounting an original and reading an image described on the original, and 3 denotes an image forming apparatus main body. A paper cassette loading section 5 for loading the paper cassette 4 of the present invention, which is provided at a lower portion of the image forming apparatus 1, is provided at a middle portion of the main body 1 of the image forming apparatus, and conveys the recording paper P vertically upward to form an image. This is an image forming mechanism employing an electrophotographic method. Reference numeral 6 denotes a paper feed roller provided above the downstream end in the paper feed direction of the paper feed cassette 4 loaded in the paper feed cassette loading unit 3 along a direction perpendicular to the paper feed direction. A transport roller for transporting the recording paper P fed from the paper feed cassette 4 by the paper roller 6 to the image forming mechanism 5. A discharge roller for discharging the discharged paper to the discharged paper receiving unit 9.

The paper cassette 4 of the present invention will be described with reference to FIGS. FIG. 2 is a perspective view showing a state in which the paper feed cassette is taken out of the image forming apparatus main body, FIG. 3 is a cross-sectional view showing the paper feed cassette in a state where the recording paper is not placed on the paper lifting plate, and FIG. FIG. 4 is a cross-sectional view illustrating the sheet cassette in a state where recording sheets are fully loaded on a push-up plate.

In this embodiment, as shown in FIG. 2, the paper feed cassette 4 is inserted into the paper feed cassette loading section 3 through an opening 3a formed in the side face of the paper feed cassette loading section 3 in the image forming apparatus main body 1. The paper is moved horizontally in a direction perpendicular to the paper feeding direction to put in and out.

In the figure, 11 is a cassette case, 12 is a paper lifting plate, 13 is an elastic member, and 14 is a paper rear end guide. The cassette case 11 has a flat rectangular box shape with an open upper surface, and has a length corresponding to the length dimension and width dimension of the maximum-size recording paper P in order to stack and accommodate a plurality of sizes of recording paper P. Dimensions and width dimensions are set. The cassette case 11 is set so that the length direction thereof is along the paper feeding direction. In FIG. 2, the right end of the cassette case 11 is on the downstream end wall in the paper feeding direction, and the left end wall is on the upstream side in the paper feeding direction. Each is set on the end wall. In FIG. 2, the right side wall portion of the cassette case 11 in the width direction is set as an inner wall portion, and the left side wall portion is set as an outer wall portion, and a handle 11a is provided on the outer wall portion.

A pair of paper width guides 21 are provided inside the two side walls in the downstream half of the cassette case 11 in the paper feeding direction. The recording paper P can be moved toward and away from each other along the width of the recording paper P, and the distance between them is adjusted according to the width of the recording paper P accommodated in the cassette case 11 to press the side edges on both sides of the recording paper P. . Cassette case 11
For example, according to the length dimensions of the three types of recording paper P, three types of distances exist in the lengthwise direction with respect to the downstream end wall portion in the paper feeding direction on both side walls in the downstream half of the sheet feeding direction. The fulcrum shaft support portions 22A to 22C are respectively formed at the defined positions.
The fulcrum shaft support portions 22A to 22C are open at the top to form a concave portion, have an axis perpendicular to the paper feeding direction, and support the fulcrum shaft 2 of the paper rear end guide 14 described later.
9 is removably fitted from above and supported swingably.

Further, on the downstream end wall portion of the cassette case 11 in the sheet feeding direction, horizontal separation claws 23 are respectively provided toward the inside of the cassette case 11.

The paper lifting plate 12 is a cassette case 11
The recording paper P is placed inside the cassette case 11 and has a rectangular shape that fits inside the cassette case 11, and both side portions overlapping the pair of paper width guides 21 are cut out to avoid this. . Upright pieces 24 are formed at right angles on both side walls of the paper push-up plate 12 near the downstream end wall in the paper feeding direction, and these upright pieces 24 have long holes 24 extending vertically. Is formed. The fulcrum shafts 26 provided on the inner surfaces of the side walls on both sides of the cassette case 11 along the direction perpendicular to the sheet feeding direction are inserted through the long holes 25 formed in each of the upright pieces 24. Thus, the sheet lifting plate 12 is supported so as to be able to swing vertically about the fulcrum shaft 26 near the upstream end in the sheet feeding direction.

The upstream half of the paper push-up plate 12 in the paper feeding direction is, for example, in the length direction based on the downstream end wall in the paper feeding direction according to the length of the three types of recording paper P. 3
Two engagement holes 27A to 24C are formed in the width direction at positions at different distances. That is, the engagement holes 2 are located at three positions facing the fulcrum shaft support portions 22A to 22C formed on the side walls on both sides of the cassette case 11, respectively.
7A to 24C are formed two by two in the width direction. Each of the two engagement holes 27 </ b> A to 24 </ b> C has a rear end claw 2 facing downward at the upstream edge (rear end) on the upstream side in the sheet feeding direction.
7a are formed.

The elastic member 13 is made of a compression coil spring, and is disposed between the bottom surface of the cassette case 11 and the sheet push-up plate 12 at the downstream end in the sheet feeding direction inside the cassette case 11. As a result, the sheet push-up plate is supported by the elastic member 13 at the downstream end in the sheet feeding direction from below, and an upward elastic force is applied.

The paper rear end guide 14 is connected to the cassette case 11.
Which is arranged along a direction perpendicular to the sheet feeding direction and has a length corresponding to the width of the cassette case 11 and a width shorter than the height of the wall of the cassette case 11. It is. Both ends of the sheet rear end guide 14 are bent at right angles to form side pieces 28, respectively, and project from the upper ends of these side pieces 28 outward in a horizontal direction orthogonal to the sheet feeding direction. A fulcrum shaft 29 is provided, and the fulcrum shaft 29 is selectively fitted from above to the fulcrum shaft support portions 22A to 22C of the cassette case 11 so as to be swingably supported. That is, the fulcrum shaft 2
Numeral 9 designates an upper end of the paper trailing end guide 14 which is pivotably supported on an axis extending in a direction perpendicular to the sheet feeding direction.

The paper trailing end guide 14 extends vertically downward from its lower edge, and engages with two engaging holes 27A to 24C formed in the paper lifting plate 12 to be engaged therewith. Piece 3
0 is formed. That is, in a state where the paper rear end guide 14 is disposed inside the cassette case 11,
Engagement holes 2 formed two by two on paper push-up plate 12
Two engaging pieces 30 are formed at two positions spaced apart in the length direction opposite to the width direction positions of 7A to 24C. The engagement piece 30 is provided in the engagement hole 27 of the sheet lifting plate 12.
A to 24C have a length protruding downward through the upper side.

The paper trailing end guide 14 is set at a position corresponding to the size of the recording paper P placed on the paper lifting plate 12, that is, the length in the paper feeding direction. For example, the length of the recording paper P is set at the fulcrum shaft support portions 22A to 22A of the cassette case 11.
22B (the engaging holes 27A to 2B of the paper lifting plate 12).
7C), the fulcrum shaft 26 is fitted to the fulcrum shaft support portion 22B of the cassette case 11, and the engagement piece 30 is engaged with the engagement hole 27B of the paper lifting plate 12. I do. As a result, the upper end of the sheet rear end guide 14 is pivotally supported, and the lower end is engaged with and supported by the sheet lifting plate 12.

Here, the engagement hole 27A of the paper lifting plate 12
A description will be given of a relationship between the engagement piece 30 of the sheet rear end guide 14 and the engagement piece 30 of the sheet rear end guide 14. Basically, when the paper lifting plate 12 is in the horizontal position, the paper trailing end guide 14 is supported by the fulcrum shaft 29 and is suspended by its own weight, and the paper lifting plate 12 is supported by the fulcrum shaft 26 as a fulcrum. When the downstream end in the sheet feeding direction swings upward, the engaging piece 30 is pushed by the upstream edge in the sheet feeding direction of the engagement holes 27A to 24C and moves toward the downstream in the sheet feeding direction. Then, the entire sheet rear end guide 14 is in a positional relationship of swinging toward the downstream side in the sheet feeding direction at an angle corresponding to the upward swing angle of the sheet push-up plate 12 with the fulcrum shaft 29 at the upper end as a fulcrum. Therefore, in order to enable the engagement piece 30 to move smoothly toward the downstream side in the paper feeding direction when the paper lifting plate 12 swings upward, the engagement holes 27A to 24C are arranged upstream in the paper feeding direction. A rear end claw 27a is formed at the side edge so as to abut against and press the engagement piece 30, and the engagement holes 27A to 24
It is a long hole along the paper feeding direction of C.

The paper feed cassette 4 configured as described above will be described. The cassette case 11 of the paper feed cassette 4 is taken out of the paper feed cassette loading section 3 of the image forming apparatus main body 1 through the opening 3a, and the paper push-up plate 12 is manually pressed against the spring force of the elastic member 13 as shown in FIG. Then, the paper push-up plate 12 is pivoted downward about the fulcrum shaft 26 to a horizontal position. The recording paper P is accommodated in the cassette case 11 from the upper side, and is stacked and placed on the paper lifting plate 12. Here, the paper trailing end guide 14 is
9 and is suspended by its own weight.
Is in contact with the rear end claw 27a of the engagement hole 27, and is prevented from swinging upstream in the sheet feeding direction. The upstream end (rear end) of the recording sheet P in the sheet feeding direction is brought into contact with the front surface of the sheet rear end guide 14 to determine and align the position in the sheet feeding direction. The downstream end (front end) of the recording paper P in the paper feeding direction is a position where it is hooked on the separation claw 23 of the cassette case 11. When the recording paper P is fully loaded and stacked on the paper rear end guide 14, the state shown in FIG.

When the hand is released, the elastic member 13 is moved to the sheet lifting plate 1.
2 is pushed up to swing upward with the fulcrum shaft 26 as a fulcrum. The downstream end (front end) of the uppermost layer of the recording papers P stacked and mounted on the paper push-up plate 12 in the paper feeding direction is caught by the separation claw 23 of the cassette case 11 and pressed from above, so that the paper push-up plate 12 is pressed. Upward swing is prevented.

Then, in this state, the cassette case 11 is inserted into and loaded into the sheet cassette loading section 3 through the opening 3a. When the paper supply roller 6 provided in the image forming apparatus main body 11 is rotated in the paper supply direction, the paper supply roller 6 comes into frictional contact with the uppermost recording paper P and applies a conveying force toward the downstream side in the paper supply direction.
As a result, the uppermost recording paper P comes off the separation claw 23 and is conveyed from the cassette case 11 to the downstream side in the paper feeding direction.

When the recording paper P is sequentially fed out and the number of recording papers P placed on the paper lifting plate 12 is sequentially reduced, the paper lifting plate 12 is moved by the elastic member 1 in accordance with the decrease.
3 and swings upward about the fulcrum shaft 26. Then, the engagement piece 30 is moved toward the downstream side in the paper feeding direction by being pushed by the rear end claw 27a of the engagement hole 27B, and the entire paper rear end guide 14 is supported on the fulcrum shaft 29 at the upper end as the fulcrum. Swings toward the downstream side in the paper feeding direction at an angle corresponding to the upward swing angle. Due to the swing of the paper rear end guide 14 toward the downstream side in the paper feeding direction, the recording paper P placed on the paper lifting plate 12 is moved in the paper feeding direction by a distance corresponding to the swing angle of the paper rear end guide 12. It is moved forward toward the downstream side.
That is, when the paper rear end guide 12 swings upward, the downstream end of the recording paper P in the paper feeding direction is removed from the position where the separation claw 23 of the cassette case 11 vertically overlaps.
However, the paper trailing end guide 14 moves the recording paper P forward by a distance corresponding to the swing angle of the paper trailing end guide 12 toward the downstream side in the paper feeding direction. This prevents the portion from coming off the position vertically overlapping the separation claw 23 of the cassette case 11. For this reason, the downstream end of the recording paper P in the paper feeding direction can be held at a position where it overlaps and hooks on the separation claw 23 of the cassette case 11 vertically. When the recording paper P placed on the paper lifting plate 12 runs out, the downstream end of the paper lifting plate 12 in the paper feeding direction is caught by the separation claw 23 as shown in FIG.

Therefore, even if the number of recording papers P to be placed decreases and the paper lifting plate 12 swings upward, the recording papers P do not come off from the separation claws 23 and a good paper feeding operation can be performed. It can be performed. Further, only when the paper lifting plate 12 swings upward, the paper trailing end guide 14 swings to the downstream in the paper feeding direction at an angle corresponding to the swing angle, and pushes the recording paper P toward the paper feeding downstream. Since the recording paper P is moved, the recording paper P can be moved by a necessary amount and hooked on the separation claw 23 of the cassette case 11 when it is necessary to hook the recording paper P on the separation claw 23 of the cassette case 11. Therefore, the paper rear end guide 12 does not always apply a strong force to the recording paper P on the downstream side in the paper feeding direction, unlike the case where the paper is always pressed by the spring force. Even if the number of recording papers P to be loaded decreases and the paper lifting plate 12 swings upward, the paper trailing end guide forcibly presses the paper with a strong force and presses the paper against the paper feed roller 6. A good paper feeding operation can be performed without losing.

Then, as shown in FIG. 2, in the sheet cassette loading section 3 of the image forming apparatus main body 1, the opening 3
The three detection switches 41A to 41C are provided on the back side surface portion opposing a, facing the fulcrum shaft support portions 23A to 23C of the cassette case 11, respectively. This detection switch 41A
For example, a microswitch is used for the lead wire 4C.
2 to a control circuit (not shown) provided in the image forming apparatus main body 1. When the sheet cassette 4 is loaded into the sheet cassette loading section 3 by moving the sheet cassette 4 in a direction perpendicular to the sheet feeding direction, the sheet cassette 4 is selectively fitted to the fulcrum shaft support sections 23A to 23C of the cassette case 11. The end of the fulcrum shaft 29 of the combined paper rear end guide 14 presses the operating elements of the detection switches 41A to 41C facing the fulcrum shaft support portions 23A to 23C to which the fulcrum shaft 29 is fitted and supported. As a result, the detection switches 41A to 41C that have been pressed generate signals, whereby the size of the recording paper P stored in the cassette case 11 can be easily detected. The detection signal is used for displaying the size of the recording paper P by a display device (not shown) provided in the image forming apparatus main body 1 and for operating the image forming apparatus such as the operation of the image forming mechanism 5 and the rollers 6 and 7. be able to.

The present invention is not limited to the above-described embodiment, but can be implemented with various modifications. For example, the paper handled by the paper feed cassette is not limited to recording paper, and for example, can also handle an original.

[0041]

According to the paper feed cassette of the first aspect of the present invention, when the paper push-up plate swings upward, the rear end of the engagement hole formed in the paper push-up plate becomes the paper rear end guide. The paper rear end guide swings to the downstream side in the paper feeding direction with the upper end pivot as a fulcrum, and pushes out the rear end of the paper placed on the paper lifting plate to push out the paper. By moving the sheet to the downstream side in the sheet feeding direction, the front end of the sheet can be held at a position where the sheet is hooked on the separation claw provided on the cassette case. Therefore, even if the number of sheets to be placed decreases and the sheet push-up plate swings upward, a good sheet feeding operation can be performed without the sheets coming off the separation claws. In addition, only when the paper lifting plate swings upward, the paper trailing end guide swings forward at the downstream side in the paper feeding direction at an angle corresponding to the swing angle to move the paper toward the downstream side in the paper feeding direction. Therefore, the sheet can be moved by a necessary amount and hooked on the separation claw of the cassette case at a time when it is necessary to hook the sheet on the separation claw of the cassette case. Accordingly, the paper rear end guide does not always apply a strong force to the paper downstream in the paper feeding direction unlike the case where the paper is constantly pressed by the spring force. Even if the number of sheets to be loaded decreases and the paper push-up plate swings upward, the paper trailing edge guide does not force the paper with a strong force and press it against the paper feed roller to bend. The sheet feeding operation can be performed well.

According to the image forming apparatus of the second aspect,
By simply loading the paper cassette into the paper cassette loading section of the image forming apparatus main body, the size of the paper accommodated in the paper cassette can be easily detected, and the information can be utilized in the operation of the image forming apparatus. .

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically illustrating an image forming apparatus equipped with a sheet feeding device according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a state in which the sheet cassette in the embodiment is removed from the image forming apparatus main body.

FIG. 3 is a cross-sectional view illustrating the sheet cassette according to the embodiment.

FIG. 4 is a cross-sectional view illustrating the sheet cassette according to the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus main body, 3 ... Paper feed cassette loading part, 4 ... Paper feed cassette, 11 ... Cassette case, 12 ... Paper push-up plate, 13 ... Elastic member, 14 ... Paper rear end guide, 22A-22C ... Support point Shaft support, 26: fulcrum shaft, 27A to 27C: engagement hole, 27a: rear end claw, 29: fulcrum shaft, 41A to 41C: detection switch, P: original (paper).

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3F343 FA02 FB02 FB03 FB04 FC01 GA03 GB01 GC01 GD02 HA16 HB03 HC28 HD09 HD18 JA01 JD11 KB02 KB03 KB20 MA03 MA26

Claims (2)

[Claims] A cassette case having a separation claw provided at a downstream end portion of the opening portion in a sheet feeding direction at an opening portion and a stack of sheets stored therein; and a cassette case disposed inside the cassette case. A downstream end portion in the sheet feeding direction is swingably supported along the vertical direction so as to approach and separate from the separation claw of the cassette case, and an engagement hole is formed in the upstream end portion in the sheet feeding direction. A sheet push-up plate on which sheets stacked and accommodated in the cassette case are placed; an elastic member that applies an upward elastic force to the sheet push-up plate; The upper end is arranged upright above the side end, and the upper end is pivotally supported by the cassette case with an axis extending along the direction intersecting the sheet feeding direction, and the lower end engages with the engaging hole of the sheet lifting plate. And placed on the paper lifting plate A paper rear end guide for pressing the upstream end of the fed paper in the paper feeding direction on the upstream side in the paper feeding direction, and the engagement hole of the paper lifting plate is provided when the paper lifting plate swings upward. A sheet cassette, wherein the upstream edge of the engagement hole in the sheet feeding direction pushes the sheet rear end guide toward the downstream side in the sheet feeding direction to swing. 2. An image forming apparatus main body having a paper feed cassette loading section, an image forming mechanism provided in the image forming apparatus main body, and a paper feed cassette loading section of the image forming apparatus main body in a paper feeding direction. The paper cassette according to claim 1, wherein the paper cassette is loaded so as to be able to be taken in and out in a direction orthogonal to the paper cassette, and the paper cassette is provided in the paper cassette when the paper cassette is loaded. An image forming apparatus provided with a detection switch for detecting a paper size operated by a rear end guide.