JPH0632489A - Universal paper feeding cassette for image forming device - Google Patents

Abstract

PURPOSE:To operate a discriminating means surely and stably by providing a spring member to be in pressure contact with the cam member of a change- over means by pressing a paper sheet size discriminating means by an actuator, when a universal paper feeding cassette is installed. CONSTITUTION:The sizes of the A line and the B line are discriminated by the projection and the retraction of the topmost end 183D of a paper sheet size discriminating member 18D linking to the movement of a paper sheet width regulating plate 13B. That is, a cam plate 17D and a cam follower 16D are arranged so that the paper sheet width regulating plate 13B can change over the size change of the discriminating means 18D, and the detection is carried out by detecting the movement of the actuator 104D of a paper sheet size detecting means 100 by a tact switch 105D. At the movable contact of the intermittent operation switch 105D, the flange of a plunger 105D is energized to put pressure contact with a coil spring 107D. As a result, a pressing means to put pressure contact with the cam plate 17D to the cam follower 16D is not necessary to provide in particular, and the structure of the detecting means 100 is made sure and simple.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention stores a stack of paper sheets of various sizes used in an image forming apparatus such as a copying machine or a laser beam printer, and loads them in a paper feeding section of the image forming apparatus. The present invention relates to an image forming apparatus provided with a universal paper feed cassette for making paper.

[0002]

2. Description of the Related Art In the above various image forming apparatuses, plain paper, printing paper, photosensitive paper, pressure-sensitive paper, thermal paper, electrostatic recording paper,
When feeding cut paper such as transfer paper and synthetic resin recording sheet to the paper feeding device of the main body of the apparatus, the paper is stored in a paper feeding cassette in order to facilitate setting, replenishment and replacement, and the cassette of the main body of the apparatus. A so-called cassette paper feeding method is adopted in which the paper is loaded into the receiving portion and fed.

In the above cassette sheet feeding system, a sheet feeding cassette containing cut sheets of a desired paper quality and size is loaded in a cassette receiving portion of the apparatus main body, and is fed by a sheet feeding roller or a sheet feeding belt of the sheet feeding device. Using the frictional force and the separating means in combination, the cut sheets are taken out one by one from the uppermost layer and fed to the image forming unit.

Further, in a copying machine or printer, a cassette selecting means for selectively setting a plurality of recording papers on the operation panel and an automatic paper feed selection function (APS) for automatically selecting a recording paper corresponding to a document size and a copy magnification. ), An automatic magnification selection function (AMS) that sets the size of the paper to be recorded and automatically selects an appropriate magnification, and a variable length exposure unit that switches the scanning exposure length according to the size length of the copy paper. Therefore, a paper size detecting means for identifying the paper size is provided.

At the tip of each paper feed cassette, there is a paper size detection frame for identifying the size of the stacked paper. When the paper feed cassette is set in an image forming apparatus such as a copying machine, the paper size detection frame is a combination of the switches installed in the image forming apparatus to turn on and off, and the paper stored in the paper feeding cassette is set. It is designed to identify the size.

In the conventional dedicated cassette, only one kind of paper size can be accommodated in one paper feed cassette, and it is necessary to prepare a paper feed cassette for each paper size. An image forming apparatus having a plurality of sheet feeding units to be mounted is upsized.

Further, in an image forming apparatus having a small number of paper feed units, not only is a paper feed cassette exchanging device troublesome, but a space for accommodating a spare paper feed cassette is required.

In the above-mentioned image forming apparatus, the recording paper size is diversified (A6 to A3 size, B6 to B4 size, postcard size, various sizes of USA, etc.), space saving of a dedicated paper feeding cassette, and low device cost. In order to achieve high quality, one paper cassette can be loaded with various types of recording paper of different sizes.
A so-called universal paper cassette that can be fed is used.

In the universal paper feed cassette, in order to load and feed recording sheets of different sizes, a paper width regulating plate for limiting the left and right positions of the recording sheets and a trailing edge regulating member for limiting the trailing edge of the recording sheets are moved. It is possible to set it according to the size of the recording paper.

If a universal paper cassette is used,
Although the number of paper feed cassettes may be small, there is a disadvantage in that the operation of selectively installing the paper width regulating plate, the trailing edge regulating member, the paper size detecting frame, etc. is complicated and laborious each time the paper size is changed.

[0011]

In such a universal sheet feeding cassette, as the movable rear end regulating member,
The following are known.

A sheet cassette body provided with a detachable sheet rear end positioning member (Jitsuko Sho 54-20777).

A guide plate for regulating the lengthwise direction of the sheet is movable in the sheet feeding direction (Japanese Patent Laid-Open No. 3-166129).

In the above, the sheet trailing edge positioning member must be removed and fixed at the set position every time the recording paper size is changed. Therefore, when the paper size is changed frequently, the operation is troublesome and unsuitable. .

In the above, since the guide plate is continuously movable in the paper feeding direction, not only is it troublesome to move the guide plate and then fix it at a predetermined position, but also the structure is complicated and the manufacturing cost becomes high. There are drawbacks.

Further, as the type detecting device of the paper feed cassette, there are disclosed in Japanese Utility Model Laid-Open No. 53-118531, Japanese Patent Laid-Open No. 62-175330, and Japanese Patent Publication No.
06828, Tokuhei 1-222172, Actual Kaihei 1-129137, Actual Kaihei
Although the respective publications of 1-83733 are disclosed, all of them have complicated devices.

[0017]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems, and a sheet size detecting frame in a universal sheet feeding cassette capable of selecting and storing sheets of various sizes. In addition to enabling quick and easy one-touch selection operations,
The purpose is to ensure and stabilize the operation of the paper size identification means of the universal paper feed cassette and reduce the manufacturing cost.

A universal paper feeding cassette of an image forming apparatus of the present invention which achieves the above object, is a cassette main body capable of selectively accommodating a plurality of sizes of paper in the same cassette main body, and a size of the paper. A movable guide member, a plurality of switchable sheet size identification members for identifying the size of stacked sheets, and a movable cam member that switches the sheet size identification members in conjunction with the movement of the guide member. And a movable actuator that is provided in a paper feed section of an image forming apparatus in which the universal paper feed cassette is mounted, is arranged to face the paper size identification means, and is movable. The actuator, and when the universal paper feed cassette is installed, the actuator sets the paper size. It is characterized in that it comprises a sheet size detecting means and a spring member for pressing the cam member of the switching means to press the identification means.

Further, the universal sheet feeding cassette of the image forming apparatus of the present invention has a cassette body capable of accommodating sheets of a plurality of sizes and selectively stacking them in the same cassette body.
A guide member that is movable according to the size of the paper, a plurality of switchable paper size identification members for identifying the size of the stacked paper, and the paper size identification member that interlocks with the movement of the guide member. A universal paper feed cassette comprising a switching means composed of a movable cam member for switching and a spring member for urging the movable cam member of the switching means to bring the sheet size identification means into contact with the initial stop position, and the universal paper feeding cassette. It is characterized in that it is provided in a paper feeding section of the image forming apparatus in which the paper cassette is mounted, and is provided with a detecting means for the paper which is arranged facing the paper size identifying means.

The guide member is a paper width regulating member that regulates a direction orthogonal to the paper feed direction of the plurality of sizes of paper, and / or a paper rear of the length of the paper of the plurality of sizes in the feeding direction. It is a rear end regulating member that regulates the end.

[0021]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a copying machine equipped with a universal paper feed cassette according to the present invention. FIG. 2 is a front perspective view of the copying machine showing a state in which the upper stage of the front loading type paper feed cassette is slightly pulled out.

In FIG. 1, at the bottom of the copying machine main body 1,
Universal sheet feeding cassettes 10A and 10B are provided so as to be pulled out to the front side from the two-stage sheet feeding device 20, respectively. Since the universal sheet feeding cassettes 10A and 10B have substantially the same structure, both universal sheet feeding cassettes (hereinafter referred to as sheet feeding cassette 10) will be collectively described with the same reference numerals.

The paper feed cassette 10 comprises a cassette body 11, a movable bottom plate 12, paper width regulation plates 13A and 13B, and a paper trailing edge regulation means 19.

The paper feed unit on the side of the copying machine body 1 is connected to a drive source by a paper feed table 21 for accommodating and fixing the paper feed cassette 10 at a predetermined position and a push-up lever 22 for pushing up the movable bottom plate 12. A sheet feeding device including an elevating / lowering drive unit 20 that swings around a swing support shaft 23, a feed roller (pickup roller) 31, a feed roller 32, a reverse roller 33, a swing shaft (feed roller shaft) 34, and the like. The roller unit 30 includes a movable guide plate 41, a fixed guide plate 42, an intermediate conveyance driving roller 43, and a conveyance unit 40 including a driven roller 44.

The recording paper P loaded on the movable bottom plate 12 of the paper feed cassette 10 is a push-up lever which is operated by a paper feed signal.
22 and the movable bottom plate 12 are raised, and the pickup roller 31 is lowered and rotated to be fed out, and then the feed roller 32 is continuously fed.
The reverse roller 33 is fed to the nip position and conveyed, and further passes through the intermediate conveyance drive roller 43 and the driven roller 44,
When the front end of the recording paper P is detected by the straight-ahead sensor 46 of the registration roller 45, it is stopped under the control of the CPU. At this time, a toner image is formed on the image forming body (photosensitive drum) 3 by charging by the charger 4, image exposure of the original by the scanning optical system 2, and development by the developing device 5.

Next, the registration roller 45 is rotated in accordance with the above-mentioned image forming timing, and the recording paper P is conveyed to the transfer area by the transfer device 6A in accordance with the peripheral speed of the image forming body 3 and is transferred onto the image forming body 3. The formed toner image is transferred onto the recording paper P.

The recording paper P on which the toner image is transferred is separated from the peripheral surface of the image forming body 3 by the separator 6B and is conveyed by the conveyor belt 7, and the fixing device 8 and the paper feeding portion 9 are provided.
It is placed on the paper discharge tray 92 via the paper discharge rollers 91.

FIG. 3 is a rear perspective view of the universal sheet feeding cassette 10 according to the present invention, FIG. 4 is a sectional view of the sheet feeding cassette, FIG. 5 is a partially cutaway plan view of the sheet feeding cassette, and FIG. FIG. 9 is a bottom perspective view of the paper cassette with the bottom cover 119 removed.

One end of the movable bottom plate 12 on which the sheets of paper P are stacked and placed is rotatably locked to a part of the bottom surface of the cassette body 11, and the other end of the movable bottom plate 12 is interleaved when the movable bottom plate 12 swings up. It presses against the peripheral surface of the pickup roller 31.

FIG. 7 shows the paper width regulating plates 13A and 13 in FIG.
FIG. 6 is a plan view of an interlocking mechanism of B, a paper size identification unit, and a paper size detection unit.

In FIG. 5, the two sheet width regulating plates (width regulating guide members) are provided on the upper surface of the bottom of the cassette body 11.
13A and 13B are provided so as to be movable parallel to the paper feeding direction. The paper width regulation plates 13A and 13B are formed in guide grooves 111A and 1A formed in the bottom of the cassette body 11 and orthogonal to the paper feeding direction.
The rack plates 14A and 14 shown in FIG.
The B and the pinion 15 can move in conjunction with each other, and the sheets can be positioned and aligned by contacting both side surfaces of the stacked sheets housed in the cassette body 11.

A cam follower 16D is swingably supported on the bottom rear surface of the cassette body 11. FIG. 7 shows the maximum paper width (for example, A3 size 297 mm width) and the paper width regulation plate 13
It is a top view which shows the state which set A and 13B. In this state, the claw portion 16a of the cam follower 16D is pressed against the upright cam surface 172D of the cam plate 17D that is fixed to the one rack plate 14B that is connected to the paper width regulation plate 13B and is integral with the paper width regulation plate 13B. Swing is blocked. The arm portion 16b of the cam follower 16D has a pin 181D at one end of the paper size identification member 18D.
And the pin 181D is connected to the arc-shaped groove 1 of the cassette body 11.
Can be moved along 12. Paper size identification member 18
The other end 182D of D is movable by being guided by the guide protrusion of the cassette body 11. The most distal end portion 183D of the paper size identification member 18D has a bent shape, and the actuator 104D of the paper size detection means 100 provided on the copying machine main body 1 side described later.
Approach or leave.

FIG. 8 is a plan view of the interlocking mechanism of the paper size detecting means 100 showing a state where the paper width regulating plates 13A and 13B are manually moved to set a narrower paper width. When the sheet width regulating plates 13A and 13B are moved toward the center line CL, a cam plate fixed to a rack plate 14B which is integral with the sheet width regulating plates 13A and 13B.
17D cam surface 172D and cam follower 16D claw portion 16a
When the cam follower 16D is disengaged from the cam follower 16D, the cam follower 16D can be swung, and is biased by a spring (not shown) to rotate counterclockwise. By the swing rotation of this cam follower 16D, the pin
181D pushes down the paper size identifying member 18D in the direction of the broken line arrow in FIG. 7, and the paper size identifying member 18D is held in a stopped state at the position where the pin 181D abuts the end of the arcuate groove 112. At this time, the leading edge 183D of the paper size identification member 18D
Is stored at a position retracted from the front end surface 114 of the cassette body 11.

In FIG. 2, an intermediate wall body 101 forming a part of the casing of the copying machine main body 1 is fixedly installed at the innermost side of the front loading paper feeding device of the copying machine main body 1. On the front side of the intermediate wall body 101, there are arranged a paper feed table and a paper feed device for accommodating the paper feed cassettes 10A and 10B. Behind the intermediate wall body 101, a drive mechanism for driving the image forming means of the copying machine and the paper feeding and discharging conveying device is arranged.

On the intermediate wall 101, an electric circuit board 102 on which a power supply circuit and a drive circuit of the copying machine are arranged is fixedly provided. A sheet size detecting means 100, which will be described later, is provided on the front side of the electric circuit board 102, and the actuator tip portion thereof projects forward through the through hole 101A of the intermediate wall body 101, and the rear portion of the sheet feeding cassette 10A, 10B. It faces the sheet size identification members 18A, 18B, 18C, 18D provided on the side walls.

The paper size detecting means 100 arranged on the electric circuit board 102 is slidable on the inner wall surface of a common fixed holder 103, for example, four actuators 104 shown in the figure.
It has A, 104B, 104C and 104D. As a representative of these, the inside of one of the actuators 104D is shown in partial sectional views of FIGS. Inside the fixed holder 103, a tact switch 105D is fixedly mounted on the electric circuit board 102.

At the movable contact of the tact switch 105D, the flange of the plunger 106D is connected to the coil spring 107.
It is urged by D and is in pressure contact. The coil spring 107D
Has one end pressed against the flange portion of the plunger 106D and wound around the pin portion, and the other end pressed against the abutting surface of the bottom of the deep hole of the actuator 104D to be held in a compressed state. The front end of the actuator 104D is arranged to face the leading edge 183D of the paper size identification member 18D of the universal paper feed cassette 10. Similarly, the other actuators 104A, 104B, 104C have paper size identification members 18A, 18B, 18 interlocking with a paper trailing edge regulating means 19 described later.
Press or release to C and 18D respectively.

FIG. 9 is a plan view showing the arrangement of sheets of various sizes that can be stored in the universal sheet feeding cassette, and FIG. 10 is an explanation of the sheet width regulating plates 13A and 13B, the sheet trailing edge regulating means 19, and the sheet arrangement. FIG.

In the paper arrangement shown in FIG. 9, the size of the horizontally placed paper is detected by detecting the stop position (Y1 to Y7) of the paper trailing edge abutting plate 191 of the paper trailing edge regulating means 19 which moves in the direction parallel to the paper feeding direction. However, as shown in FIG. 10, with A4 and A5R, it cannot be determined only by the stop position of the sheet trailing edge abutting plate (guide member) 191 of the sheet trailing edge regulating means 19. Therefore, the two are discriminated by the amount of movement of the paper width regulating plates 13A, 13B. Similarly, the discrimination between B5 and B6R is also made by moving the sheet width regulating plates 13A and 13B. The size of each of the rows A and B is determined by the sheet width regulation plate 13A,
The leading edge portion 183D of the sheet size identifying member 18D, which is interlocked with the movement of 13B, is identified by the protrusion and the withdrawal.

That is, the paper width discriminating plates 13A and 13B pass through the T1 position of the A4 width and the T2 position of the B5 width and reach the T3 position of the A5R width. The cam plate 17D and the cam follower 16D are arranged so that the switching can be performed. This allows papers A4 and A5R, B5 and B6R of the same length
Means that the actuator 104 of the paper size detecting means 100 is caused by the projection and retraction of the paper size identification member 18D.
It is possible to detect the movement of D by detecting the tact switch 105D.

The pressing force of the coil spring 107D which presses and holds the actuator 104D is a spring pressure of a strength for sliding the cam follower 16D against the cam plate 17D, which is a movable cam member, and the tact time. Switch 105D
The operating pressure is set below.

Next, the interlocking mechanism of the paper trailing edge regulating means 19 and the paper size identifying members 18A, 18B, 18C will be described with reference to FIGS.

The paper trailing edge regulating means 19 includes a paper trailing edge abutting plate (guide member) 191 that regulates the trailing edge of a bundle of sheets housed in the universal paper feeding cassette to align the sheets, and the abutting plate 191. A slide member 193 that holds the cassette upright and moves in the cassette body 11 along the two guide grooves 192 in the sheet feeding direction, and roller-shaped cam followers (rollers) 16A, 16B, 16C fixed to the slide member 193. It consists of and.

On the other hand, on the bottom rear surface side of the cassette body 11,
One end of a cam plate 17A, 17B, 17C which is fitted to the pins 171A, 171B, 171C and is swingable is supported. These cam plates 17A, 17B and 17C are respectively flat plate cam surfaces 17
2A, 172B and 172C are formed. Also, the cam plate 17
The other ends of A, 17B, 17C are pins 173A, 173B, 17 respectively.
It is rotatably connected to the sheet size identification members 18A, 18B and 18C by 3C.

When the abutting plate 191 of the paper trailing edge regulating means 19 is moved in the paper feeding direction, a slide member 193 integral with the abutting plate 191 is formed.
The upper cam followers 16A, 16B and 16C are brought into pressure contact with the flat plate cam surfaces 172A, 172B and 172C, respectively, and the cam plate 17 is pressed.
A, 17B and 17C are rocked to allow the paper size identification member 18A,
By moving 18B and 18C, the most distal end thereof projects or retracts. The entry / exit state of the leading edge is determined by the actuators 104A, 104B, 104 of the paper size detecting means 100.
When C receives it, the tact switch is activated to generate a paper size detection signal.

Table 1 shows Bit patterns for domestic / Europe, and shows various paper sizes and the protruding states of the paper size identification members 18A to 18D for identifying the various paper sizes. In the table, the mark ◯ indicates the protruding state of the identification members 18A to 18D, that is, the switch-on state by pressing the actuators 104A to 104D in FIG.

Table 2 shows a Bit pattern for identifying inch size paper for the United States.

[0049]

[Table 1]

[0050]

[Table 2]

Even in the paper size discrimination by the paper trailing edge regulating means 19, the pressing force of the cam plates 17A, 17B, 17C to the cam followers 16A, 16B, 16C is determined by the actuators 104A, 104B of the paper size detecting means 100. , 104C
It is performed by the spring pressure of each coil spring that presses, and no separate biasing means is required.

Next, tension springs 174, which are weaker than the pressing force of the coil spring 107D, are stretched between the respective parts of the cam plates 17A, 17B, 17C and the cassette main body 11 so that the paper size identifying members 18A, By holding 18B and 18C in the protruding state, the frictional resistance between the respective members constituting the paper size identifying means is reduced, and even if the slidability is deteriorated by the means, the identifying means is always stable and smooth. Can be activated.

The universal paper feed cassettes 10A and 10B
The recording paper P having a predetermined paper size is accommodated in the paper, and the paper width regulating plates 13A and 13B and the paper rear end regulating means 19 are slid to align the paper according to the paper size, and then the paper feed cassette 10A. , 10B are mounted in the paper feeding device 20 of the copying machine main body 1, and are accommodated in the universal paper feeding cassette loaded in the copying machine main body 1 by selectively connecting the tact switch by connecting the identification means and the detection means. Since the size of the selected paper is identified, a desired paper P is selected from the selected paper feed cassette by a key operation on the operation panel of the copying machine body 1 or a command such as an automatic paper feed selection function (APS). Sent out.

In the above embodiment, the universal paper cassette of JIS standard paper size is explained.
A similar paper size detection means can be configured for a universal paper feed cassette that accommodates American standard inch size paper. Further, the paper size detecting means of the present invention can be applied to a copying machine capable of accommodating various papers of both JIS standard and US standard size in one universal paper feed cassette.

In the above embodiment, the image forming apparatus of the front loading type and the paper width center standard feeding type has been described, but the present invention is not limited to these, and the side loading type or the one side standard feeding type. Of course, it can be applied to the universal paper cassette of the type.

[0056]

As described above, according to the universal sheet feeding cassette of the image forming apparatus of the present invention, one cassette body can selectively accommodate a plurality of sheet bundles, and in particular, the cassette can be accommodated. It is possible to easily detect the size of the recording paper accommodated therein continuously following the operation of the paper alignment regulation member. Further, since it is not necessary to particularly provide a pressing means for pressing the cam plate connected to the paper size identifying member in the paper feed cassette to the cam follower at the time of detecting the paper size, the structure of the paper size detecting means becomes reliable and simple.
It is also effective in reducing manufacturing costs.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a copying machine equipped with a universal paper feeding cassette according to the present invention.

FIG. 2 is a front perspective view of the copying machine in a state in which an upper stage of a front loading type paper feed cassette is pulled out.

FIG. 3 is a perspective view of a universal sheet feeding cassette according to the present invention.

FIG. 4 is a sectional view of the paper feed cassette.

FIG. 5 is a partially cutaway plan view of the paper feed cassette.

FIG. 6 is a bottom side perspective view of the paper feed cassette.

FIG. 7 is a plan view of an interlocking mechanism of a large-size sheet identifying unit and a detecting unit.

FIG. 8 is a plan view of an interlocking mechanism of a small-size sheet identifying unit and a detecting unit.

FIG. 9 is a plan view showing the arrangement of various size sheets that can be stored in the universal sheet cassette.

FIG. 10 is a plan view illustrating the arrangement of a sheet width regulation plate, a sheet trailing edge regulation member, and a sheet.

[Explanation of symbols]

1 Copier main body 10, 10A, 10B Universal paper feed cassette (paper feed cassette) 11 Cassette main body 13A, 13B Paper width regulation plate 14A, 14B Rack plate 16A, 16B, 16C, 16D Cam follower 17A, 17B, 17C, 17D Cam Plate 18A, 18B, 18C, 18D Paper size identification member 100 Paper size detection means 101 Intermediate wall body 102 Electric circuit board 103 Fixed holder 104A, 104B, 104C, 104D Actuator 105D Tact switch 106D Plunger 107D Coil spring 171A, 171B, 171C Pins 172A, 172B, 172C, 172D Cam surface 181D Pin 183D Leading edge 19 Paper trailing edge regulating means 191 Paper trailing edge abutting plate (guide member) 192 Guide groove 193 Sliding member P Recording paper (paper)

Claims (4)

[Claims] 1. A cassette main body capable of selectively stacking and storing plural sizes of paper in the same cassette main body, a guide member movable according to the size of the paper, and a size of the stacked paper. A universal paper feed cassette including a plurality of switchable sheet size identification members for identification, and a switching unit including a movable cam member that switches the sheet size identification members in association with the movement of the guide member, and the universal paper feed cassette. A movable actuator, which is provided in a paper feeding portion of the image forming apparatus to which the paper cassette is mounted, is arranged to face the paper size identifying means, and which urges the movable actuator, and when the universal paper cassette is mounted, An actuator presses the paper size identification means to press the cam member of the switching means into contact with a spring member. A universal sheet feeding cassette for an image forming apparatus, which is provided with a sheet size detecting means. 2. A cassette main body capable of selectively stacking and storing a plurality of sizes of paper in the same cassette main body, a guide member movable according to the size of the paper, and a size of the stacked paper. A plurality of switchable sheet size identification members for identification, a switching means including a movable cam member for switching the sheet size identification members in conjunction with the movement of the guide member, and a biasing of the movable cam member of the switching means. The paper size identification means is provided in a universal paper feed cassette including a spring member that abuts the paper size identification means at an initial stop position, and a paper feed unit of an image forming apparatus in which the universal paper feed cassette is mounted. A universal sheet feeding cassette for an image forming apparatus, which is provided with a sheet detecting unit arranged to face the sheet detecting unit. 3. The image forming apparatus according to claim 1, wherein the guide member is a paper width restricting member that restricts a direction orthogonal to a paper feeding direction of the plurality of sizes of paper. Universal paper cassette. 4. The image forming apparatus according to claim 1, wherein the guide member is a trailing edge regulating member that regulates a trailing edge of a sheet having a length in a feeding direction of the sheets of the plurality of sizes. Universal paper cassette for the device.