JP2008133087A - Sheet material detecting device, paper feeder having the device and image forming device having the paper feeder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet material detecting device capable of detecting the presence of a sheet material of small size, without having influence on carrying of the sheet material, a paper feeder having this device and an image forming device having this paper feeder. <P>SOLUTION: When placing the sheet material P on a placing plate, a lever member 18 rotates in the arrow B direction, and a shutter member 34 moves from between transmission sensors 36, and recognizes that there is the sheet material P. The placing plate is moved upward, and the sheet material P is brought into pressure contact with a feed roller 10. The lever member 18 rotates in the arrow B direction when the placing plate moves upward, and since a rib member 32 moves the lever member 18 in the arrow C direction by abutting on a spiral member 30, the lever member 18 does not interfere with the feed roller 10. Thus, since the lever member 18 can be arranged in the vicinity of a central part in the sheet material width direction, the presence of the sheet material P of small size can be detected without having influence on the carrying of the sheet material P. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sheet material detection device that detects the presence or absence of a sheet material, a sheet feeding device including the sheet material detection device, and an image forming apparatus including the sheet feeding device.

A sheet feeding device that feeds a sheet material to an image forming unit includes a sheet feeding roll that conveys the sheet material placed on the placement plate, and a sheet material detection device that detects the presence or absence of the sheet material placed on the placement plate. It has. (Patent Document 1)
Specifically, the sheet material detection device includes a lever member that rotates in contact with the sheet material placed on the placement plate, and a sensor that detects the presence or absence of the sheet material based on the rotation position of the lever member. The lever member is provided at two locations, that is, a central portion in the width direction of the sheet material and a side portion, thereby detecting the presence / absence of the sheet material and the size of the sheet material. Further, based on this detection information, a sheet feeding roll provided in the sheet feeding device conveys the sheet material at a timing corresponding to the size of the sheet material. (Patent Document 1)
JP 2004-51253 A

  However, according to this sheet material detection device, the lever member is provided at the center in the width direction of the sheet material in order to detect the presence or absence of a small sheet material. In order to avoid the interference with the lever member, it is conceivable that the sheet feeding roll for conveying the sheet material is arranged so as to be shifted from the central portion in the width direction of the sheet material in the rotation axis direction, and the conveyance of the sheet material is not stable.

  An object of the present invention is to detect the presence or absence of a small-sized sheet material without affecting the conveyance of the sheet material in consideration of the above facts.

  A sheet material detection apparatus according to a first aspect of the present invention is a sheet material detection apparatus that detects a sheet material that is placed on a placement plate and conveyed by a paper feed roll, and is rotatably supported by the apparatus body. A shaft member having an axial direction intersecting the sheet material conveying direction, a lever member fixed to the shaft member and rotating in contact with the sheet material placed on the mounting plate, and the lever member A detection member that detects the presence or absence of a sheet material based on the rotation position of the sheet member, and when the sheet material moves toward the sheet feeding roll and the lever member rotates, the lever member is moved in the axial direction of the shaft member. And a moving means for moving the paper toward the paper and separating the paper from the paper feed roll.

  According to the above configuration, the lever member fixed to the pivotable shaft member rotates in contact with the sheet material placed on the placement plate, and the detection member moves based on the pivot position of the lever member. Detect the presence or absence of material.

  Further, when the sheet material is conveyed to the image forming unit, the placement plate moves toward the paper feed roll in order to apply the sheet material to the paper feed roll.

  When the lever member is pushed by the sheet material and rotated by moving the mounting plate toward the paper feed roll, the moving means moves the lever member in the axial direction of the shaft member and moves away from the paper feed roll. Let

  For this reason, since the lever member can be disposed in the vicinity of the sheet material width direction center portion even when the sheet feeding roll is disposed in the sheet material width direction center portion in order to convey the sheet material in a stable state, The presence or absence of a small-sized sheet material can be detected without affecting the conveyance of the sheet material.

  The sheet material detection device according to a second aspect of the present invention is the sheet material detection device according to the first aspect, wherein the moving means is provided on the outer periphery of the shaft member so as to protrude in a helical shape, and is provided on the device main body, A rib member that contacts the spiral member and moves the lever member in the axial direction when the shaft member rotates.

  According to the above configuration, when the sheet material is conveyed to the image forming unit, the placement plate moves toward the paper feed roll in order to apply the sheet material to the paper feed roll. As the mounting plate moves toward the paper feed roll, the lever member fixed to the shaft member is pushed by the sheet material and rotates.

  When the shaft member rotates, the rib member provided in the apparatus main body comes into contact with the spiral member provided in the shaft member, and the lever member is moved in the axial direction to be separated from the paper feed roll.

  Thus, the lever member can be moved without using a complicated mechanism by moving the lever member in the axial direction along the spiral shape of the spiral member.

  According to a third aspect of the present invention, there is provided the sheet material detection device according to the first or second aspect, wherein the urging member that urges the lever in an axial direction opposite to a direction in which the lever member moves by the moving means. It is provided.

  According to the above configuration, since the urging member urges the lever in the direction opposite to the direction in which the lever is moved by the moving means, when the conveyance of the sheet material is finished and the placing plate is separated from the paper feed roll, the lever Is returned to its original position by the urging force of the urging member.

  For this reason, the drive means which returns a lever member to an original position becomes unnecessary.

  The sheet material detection apparatus according to a fourth aspect of the present invention is the sheet material detection apparatus according to any one of the first to third aspects, wherein the axial direction of the shaft member is orthogonal to the sheet material conveyance direction.

  According to the above configuration, since the axial direction of the shaft member is orthogonal to the sheet material conveyance direction, the lever member can be separated from the sheet feeding roll with a short movement distance.

  A sheet feeding device according to a fifth aspect of the present invention includes a placement plate on which a sheet material is placed, and a sheet material placed on the placement plate to the image forming unit and a central portion in the sheet material width direction. And a sheet material detection device according to any one of claims 1 to 4.

  According to the above configuration, since the sheet feeding device includes the sheet material detection device according to any one of claims 1 to 4, the presence or absence of a small size sheet material placed on the placement plate is detected. The sheet feeding roll that is detected and arranged in the center in the sheet material width direction can feed the sheet material to the image forming unit in a stable state.

  An image forming apparatus according to a sixth aspect of the present invention includes the paper feeding device according to the fifth aspect.

  According to the above configuration, since the image forming apparatus is provided with the paper feeding device according to claim 5, the presence or absence of a small-size sheet material on the placing plate is detected, and the paper feeding roll is provided. The sheet material can be sent out in a stable state.

  According to the present invention, it is possible to detect the presence or absence of a small-size sheet material without affecting the conveyance of the sheet material.

  An image forming apparatus 100 provided with a sheet feeding device 74 including a sheet material detection device 20 according to the present invention will be described with reference to FIGS.

  As shown in FIG. 16, the image forming apparatus 100 includes a photosensitive member 52 on which an electrostatic latent image is formed by irradiating a laser beam after being uniformly charged, and a surface of the photosensitive member 52. A charging device 54 for uniformly charging, an exposure device 56 for forming an electrostatic latent image by irradiating the photosensitive member 52 with laser light based on image data, and selectively transferring toner to the electrostatic latent image. A developing device 58 that visualizes the toner image, a transfer roll 62 that transfers the toner image on the surface of the photosensitive member 52 to a sheet material P as a recording medium supplied along the conveyance path 60, and a toner image on the sheet material P Are fixed to the sheet material P by heating and pressurizing, and a cleaning device 66 for cleaning the toner remaining on the photosensitive member 52 after the toner image is transferred.

  The image forming apparatus 100 is covered with a main body side cover 100B and a top plate 100A.

  Here, the photoconductor 52, the charging device 54, the developing device 58, and the cleaning device 66 serve as a single developing unit 67 by opening the top plate 100 </ b> A of the image forming apparatus 100, so that the main body frame (see FIG. (Not shown) can be easily attached and detached.

  The interior can be opened by rotating the top plate 100A in the direction of arrow A with a shaft 100C provided at the upper end corner of the main body side cover 100B as a fulcrum.

  Further, a sheet feeding device 74 that can manually feed the sheet material P to the image forming unit 70 is provided on the side of the image forming apparatus 100, and further, on the lower side in the image forming apparatus 100. Is provided with a paper feed cassette 80 on which a plurality of sheet materials P are stacked. The sheet material P placed on the paper feed cassette 80 is sequentially taken out by a pickup roll 82 and further conveyed one by one by a paper feed roll 84 and a separation roll 86 that are rotationally driven. Details of the paper feeding device 74 will be described later.

  The photoreceptor 52 has a photoreceptor layer on the back surface, and the potential of the exposed portion is attenuated by exposure after being uniformly charged.

  Further, the charging device 54 is a roll-shaped member that comes into contact with the photoconductor 52, and when a voltage is applied between them, a discharge is generated in a minute gap near the contact portion, and the surface of the photoconductor 52. Is charged almost in the same way. As the charging device 54, in addition to the above, a device that applies a high voltage to the electrode wire and charges the photosensitive member 52 by corona discharge can be used.

  The exposure device 56 scans the flashing laser light on the peripheral surface of the photoconductor 52 and forms an electrostatic latent image based on the image data on the peripheral surface of the photoconductor 52. As the writing device, a light emitting element such as an LED may be arranged and blinked based on the image data.

  Further, the developing device 58 includes a cylindrical developing roll 58A disposed so as to face the photosensitive member 52 in the vicinity thereof, and a developing bias voltage is applied between the developing roll 58A and the photosensitive member 52. . As a result, a developing bias electric field is formed between the developing roller 58A and the photosensitive member 52, and the charged toner is transferred to the exposed portion on the photosensitive member 52 to form a toner image.

  The transfer roll 62 is a roll-shaped member provided so as to face the photoconductor 52, and forms a transfer electric field between the transfer roll 62 and the sheet material P passing through the image forming unit 70. The toner image is transferred to the top.

  In the image forming apparatus 100 configured as described above, an image is formed as follows.

  First, the charging device 54 to which a voltage is applied uniformly charges the surface of the photoconductor 52 with a predetermined potential.

  Subsequently, the exposure device 56 forms an electrostatic latent image on the charged photoreceptor 52 based on image data read by a scanner (not shown).

  That is, an electrostatic latent image corresponding to image data is formed on the photoconductor 52 by turning on / off the laser based on video data supplied from a control device (not shown). Further, the electrostatic latent image is visualized as a toner image by toner supplied from a developing roll 58A provided in the developing device 58.

  Therefore, the sheet material P taken out from the paper feed cassette 80 by the pickup roll 82 is transferred to the transport roll 68 one by one by the paper feed roll 84 and the separation roll 86, and sent to the transport path 60 to be transferred to the photosensitive member 52 and the transfer roll 60. The toner image is transferred to the sheet material P through the image forming unit 70 between the rolls 62. The transferred toner image is fixed to the sheet material P by passing between a heating roll 64H and a pressure roll 64N provided in the fixing device 64, and discharged to the upper surface of the top plate 100A by the discharge roll 72. .

  Next, the paper feeding device 74 will be described.

  As shown in FIG. 16, the sheet feeding device 74 capable of manually feeding the sheet material P to the image forming unit 70 is provided with a cylindrical feed roll 10 that feeds the sheet material P to the image forming unit 70. .

  Further, a retard roll 12 is provided with the sheet material P sandwiched between the feed roll 10. The retard roll 12 is pivotally supported by a support member (not shown) provided at both ends, and is further biased toward the feed roll 10 by a biasing force of a coil spring provided inside the support member. .

  The retard roll 12 has a built-in torque limiter and is given a predetermined (relatively large) torque in advance, and the feed roll 10 maintains a predetermined nip pressure by a coil spring provided inside the support member. Has been. For this reason, when receiving the rotational force of the feed roll 10 through one sheet material, it rotates without moving relative to the sheet material P, but when 2 to 3 sheet materials P are multi-fed, Since the frictional resistance between the two to three sheet materials P is small, only the uppermost sheet material P is conveyed to the image forming unit 70 by the feed roll 10, and the lower layer sheet material P is the rotational resistance of the retard roll 12. Feed is blocked by force.

  Further, as shown in FIG. 4, the sheet material P sent out by the feed roll 10 is placed on a placement plate 14 that can move up and down, and both ends of the placement plate 14 in the sheet material width direction. The side guide 16 that determines the position in the width direction of the sheet material P is provided in the section so as to be movable in the direction perpendicular to the sheet material conveyance. Further, the feed roll 10 is disposed at the center in the sheet material width direction of the sheet material P positioned by the side guide 16 in order to send the sheet material P to the image forming unit 70 (see FIG. 16) in a stable state. .

  Further, as shown in FIG. 13, a lever member 18 that constitutes the sheet material detection device 20 and extends in the vertical direction is provided below the feed roll 10 when viewed from the sheet material conveyance direction. In FIG. 13, components such as the apparatus main body 24 described later are omitted in order to clarify the positional relationship between the feed roll 10 and the lever member 18.

  4, 7, and 10, a roller member 18 </ b> A that rotates in the sheet material conveyance direction is provided at the tip of the lever member 18, and the tip of the lever member 18 is placed on the mounting portion. It is inserted into a rectangular opening 14 </ b> A provided in the plate 14.

  On the other hand, as shown in FIG. 1, the base end of the lever member 18 is fixed to a columnar shaft member 22 extending in a direction orthogonal to the sheet material conveying direction. Further, the shaft member 22 is rotatably supported by a vertical rib 24A and a vertical rib 24B provided in the apparatus main body 24. Further, a coil spring 26 as an urging member is provided between the vertical rib 24A and the lever member 18, and the coil spring 26 faces the lever member 18 toward the center in the sheet material width direction (FIG. 1). The direction of the arrow A shown in FIG. In FIG. 1, in order to clarify the configuration of the sheet material detection device 20, the feed roll 10 is represented by a two-dot chain line, and other components are omitted.

  Here, on the outer periphery of the shaft member 22, a spiral member 30 protruding in a spiral shape is formed integrally with the shaft member 22, and the end portion of the spiral member 30 hits the vertical rib 24 </ b> B and contacts the coil spring 26. The position of the biased lever member 18 in the width direction is determined.

  Further, the apparatus main body 24 is provided with a convex rib member 32 that abuts on the spiral member 30 so as to extend in the vertical direction. When the lever member 18 is pushed in the sheet material conveyance direction and rotated in the arrow B direction. The rib member 32 is configured to contact the spiral member 30 and move the lever member 18 in the direction of arrow C against the urging force of the coil spring 26.

  Further, a shutter member 34 having a rectangular cross section standing in an orthogonal direction from the shaft member 22 is formed integrally with the shaft member 22 at an end portion in the arrow C direction of the shaft member 22. A transmission sensor 36 as a detection member is provided on both sides of the shutter member 34 in the sheet material width direction, and the transmission sensor 36 detects the presence or absence of the shutter member 34 between the transmission sensors 36.

  As shown in FIGS. 5, 8, 11, and 14, when the sheet material P is placed on the placement plate 14, the roller member 18 </ b> A rolls on the sheet material P and the lever member 18 moves in the sheet material conveyance direction. To turn. By rotating the lever member 18, the rib member 32 comes into contact with the spiral member 30, and the lever member 18 is moved in the direction of arrow D shown in FIGS. 11 and 14, and in this state, As shown in FIG. 2, the shutter member 34 moves from between the transmission sensors 36. Thereby, the permeation | transmission sensor 36 detects that the sheet | seat material P was mounted in the mounting board 14 (refer FIG. 5). In FIG. 2, in order to clarify the configuration of the sheet material detection device 20, the feed roll 10 is represented by a two-dot chain line, and other components are omitted. Further, in FIG. 14, parts such as the apparatus main body 24 are omitted in order to clarify the positional relationship between the feed roll 10 and the lever member 18.

  Furthermore, as shown in FIGS. 6, 9, 12, and 15, when the sheet material P is sent to the image forming unit 70 (see FIG. 16), the placement plate 14 on which the sheet material P is placed is provided. The uppermost sheet material P, which is moved upward by a lifting / lowering means (not shown) and is placed on the placing plate 14 on the feed roll 10, is pressed. Further, as the sheet material P moves upward, the lever member 18 further rotates in the sheet material conveyance direction, and the rib member 32 abuts on the spiral member 30 in the direction of arrow C as shown in FIG. The lever member 18 is further moved. In FIG. 3, in order to clarify the configuration of the sheet material detection device 20, the feed roll 10 is represented by a two-dot chain line, and other components are omitted. Further, in FIG. 15, parts such as the apparatus main body 24 are omitted in order to clarify the positional relationship between the feed roll 10 and the lever member 18.

  As shown in FIG. 9, the lever member 18 and the feed roll 10 appear to overlap and interfere with each other when viewed from the sheet material conveyance orthogonal direction. Since it moves in the axial direction, as shown in FIG. 15, the lever member 18 and the feed roll 10 are separated in the sheet material width direction and do not interfere with each other.

  With this configuration, when the sheet material P is supplied to the image forming unit 70 (see FIG. 16), the user presses an image formation instruction button. As shown in FIGS. 4, 7, and 10, when there is no sheet material P on the mounting plate 14, the shutter member 34 is positioned between the transmission sensors 36 shown in FIG. The image forming processing unit (not shown) recognizes that it is not on the mounting plate 14 from the detection information of the transmission sensor 36, and displays that there is no sheet material P on a message screen (not shown).

  On the other hand, as shown in FIGS. 5, 8, and 11, when the user places the sheet material P on the placement plate 14, the lever member 18 rotates and the tip of the lever member 18 is placed on the placement plate. 14 through the opening hole 14A. As a result, as shown in FIG. 2, the shutter member 34 moves from between the transmission sensors 36, and the image formation processing unit recognizes that the sheet material P is present from the detection information of the transmission sensor 36.

  When recognizing that the sheet material P is placed on the placement plate 14, the image forming processing unit moves the lifting means to move the placement plate 14 upward as shown in FIGS. 6, 9, and 12. The uppermost sheet material P placed on the placement plate 14 is pressed against the feed roll 10.

  Here, as shown in FIG. 13, the lever member 18 located below the feed roll 10 is rotated in the sheet material conveying direction by moving the mounting plate 14 upward. 3, when the lever member 18 rotates, the rib member 32 contacts the spiral member 30 and moves the lever member 18 in the arrow C direction.

  That is, the lever member 18 moves in the direction of the arrow C while rotating, and moves to the side of the feed roll 10 as shown in FIG. For this reason, the lever member 18 and the feed roll 10 do not interfere with each other.

  In this state, the feed roll 10 rotates and supplies the sheet material P to the image forming unit 70 (see FIG. 16).

  Further, when the supply of the sheet material P is finished and the mounting plate 14 moves downward as shown in FIG. 8, the lever member 18 can be rotated, and as shown in FIG. At the same time, the rib member 32 comes into contact with the spiral member 30 to rotate the lever member 18 in the arrow F direction.

  Further, when the sheet material P is removed from the mounting plate 14, the lever member 18 can be rotated again, and the lever member 18 is further moved in the arrow A direction by the urging force of the coil spring 26 as shown in FIG. At the same time, the rib member 32 comes into contact with the spiral member 30 and the lever member 18 is rotated in the direction of arrow F. Accordingly, as shown in FIG. 7, the tip of the lever member 18 enters the opening hole 14A, and the lever member 18 returns to its original position.

  In this way, the feed roll 10 is disposed at the center in the sheet material width direction, and further, the lever member 18 is moved in the axial direction, so that the lever member 18 is viewed below the feed roll 10 (sheet) when viewed from the sheet material conveyance direction. Therefore, the presence or absence of the small-sized sheet material P can be detected without affecting the conveyance of the sheet material P.

  Further, in order to avoid interference between the rotating lever member 18 and the feed roll 10, it is conceivable to arrange the lever member and the feed roll 10 at a distance in the sheet material conveying direction. Since the interference with the feed roll 10 can be avoided by moving the shaft 18 in the axial direction while rotating the device, the apparatus can be downsized.

  Further, by arranging the lever member 18 in the vicinity of the central portion in the sheet material width direction, the opening hole 14A of the mounting plate 14 can also be disposed in the vicinity of the central portion in the sheet material width direction, and the end surface of the opening hole 14A and the sheet material It is possible to prevent the sheet material P from being deformed by hitting the side portion of P.

  Although the present invention has been described in detail with respect to specific embodiments, the present invention is not limited to such embodiments, and various other embodiments are possible within the scope of the present invention. It is clear to the contractor. For example, in the above-described embodiment, the example in which the sheet material detection device 20 according to the present invention is adopted as a manual feed type paper feed device has been described. Good.

  Moreover, in the said embodiment, although the interference with the lever member 18 and the feed roll 10 was avoided by moving the rotation axis | shaft of the lever member 18, it replaces with this and a sheet | seat material is inclined by tilting a rotation axis | shaft. When detecting the presence or absence of P, the tip of the lever member may be positioned in the vicinity of the central portion in the sheet material width direction, and the tip of the lever member may escape to the side when rotated.

FIG. 2 is a perspective view of the sheet material detection device according to the present invention, as viewed from the inside of the image forming apparatus, showing a state where no sheet material is placed. FIG. 3 is a perspective view of the sheet material detection device according to the present invention, viewed from the inside of the image forming apparatus, showing a state where the sheet material is placed. FIG. 3 is a perspective view of the sheet material detection device according to the present invention, viewed from the inside of the image forming apparatus, showing a state in which the sheet material is placed and the sheet material is conveyed. 1 is a perspective view of a sheet feeding device employing a sheet material detection device of the present invention, viewed from the outside of an image forming apparatus, showing a state in which no sheet material is placed. FIG. 3 is a perspective view of the sheet feeding device employing the sheet material detection device of the present invention, viewed from the outside of the image forming apparatus, showing a state where the sheet material is placed. 1 is a perspective view of a sheet feeding device employing a sheet material detection device of the present invention, viewed from the outside of an image forming apparatus, showing a state in which a sheet material is placed and a sheet material is conveyed. It is the side view which showed the sheet feeder by which the sheet | seat material detection apparatus of this invention was employ | adopted, and showed the state in which the sheet | seat material is not mounted. FIG. 5 is a side view showing a sheet feeding device employing the sheet material detection device of the present invention and showing a state where the sheet material is placed. FIG. 5 is a side view illustrating a sheet feeding device in which the sheet material detection device of the present invention is employed, and a state in which the sheet material is placed and the sheet material is conveyed. 1 is a perspective view of a sheet feeding device employing a sheet material detection device of the present invention, viewed from the inside of an image forming apparatus, showing a state in which no sheet material is placed. FIG. 4 is a perspective view of the sheet feeding device employing the sheet material detection device of the present invention, as viewed from the inside of the image forming apparatus, showing a state where the sheet material is placed. FIG. 3 is a perspective view of the sheet feeding device employing the sheet material detection device of the present invention, viewed from the inside of the image forming apparatus, showing a state in which the sheet material is placed and the sheet material is conveyed. FIG. 2 is a perspective view of the sheet material detection device according to the present invention, as viewed from the inside of the image forming apparatus, showing a state where no sheet material is placed. FIG. 3 is a perspective view of the sheet material detection device according to the present invention, viewed from the inside of the image forming apparatus, showing a state where the sheet material is placed. FIG. 3 is a perspective view of the sheet material detection device according to the present invention, viewed from the inside of the image forming apparatus, showing a state in which the sheet material is placed and the sheet material is conveyed. 1 is a schematic configuration diagram of an image forming apparatus including a sheet material detection device and a paper feeding device of the present invention.

Explanation of symbols

10 Feed roll (paper feed roll)
14 Mounting plate 16 Side guide 18 Lever member 20 Sheet material detection device 22 Shaft member 24 Device body 26 Coil spring (biasing member)
30 Spiral member 32 Rib member 36 Transmission sensor (detection member)
100 Image forming apparatus

Claims (6)

A sheet material detection device that detects a sheet material mounted on a mounting plate and conveyed by a paper feed roll,
A shaft member that is rotatably supported by the apparatus main body and has an axial direction that intersects the sheet material conveyance direction;
A lever member fixed to the shaft member and rotating in contact with the sheet material placed on the mounting plate;
A detection member that detects the presence or absence of a sheet material based on the rotation position of the lever member;
Moving means for moving the lever member toward the axial direction of the shaft member when the sheet member moves toward the paper feed roll and rotates the lever member, and moves away from the paper feed roll;
A sheet material detection apparatus comprising: The moving means is
A spiral member provided in a spiral shape on the outer periphery of the shaft member;
A rib member that is provided in the apparatus main body and moves the lever member in the axial direction against the spiral member when the shaft member rotates;
The sheet material detection device according to claim 1, comprising:   The sheet material detection device according to claim 1, wherein a biasing member that biases the lever in an axial direction opposite to a direction in which the lever member moves by the moving unit is provided.   4. The sheet material detection device according to claim 1, wherein an axial direction of the shaft member is orthogonal to a sheet material conveyance direction. 5. A mounting plate on which the sheet material is mounted;
A sheet material placed on the placement plate is sent out to the image forming unit, and a sheet feeding roll disposed in the center in the sheet material width direction,
The sheet material detection device according to any one of claims 1 to 4,
A sheet feeding device characterized by comprising:   An image forming apparatus comprising the paper feeding device according to claim 5.

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