JP2020083490A - Sheet conveying device and image forming device - Google Patents

Abstract

To provide a sheet conveying device capable of detecting full loading of side-curled sheets and suppressing a sheet conveying resistance.SOLUTION: The sheet conveying device includes an actuator 86 for detecting a stacking height of sheets S discharged on a discharge tray 2B; the actuator 86 includes a central detection part 862 which can be brought into contact with a central part of the sheet S in a width direction and which extends to a downstream side in a discharge direction and a first side detection part 863 which can be brought into contact with an end part of the sheet S in the width direction and which extends to the downstream side in the sheet discharge direction; the first side detection part 863 has a first face 863C arranged at a discharge tray 2B side; the central detection part 862 has a second face 862C arranged at the discharge tray 2B side; and viewing a direction along the width direction, a first tip part 863D in the first face 863C is arranged above a virtual tangential line T including a second tip part 862D in the second face 862C.SELECTED DRAWING: Figure 5

Description

The present invention relates to a sheet conveying device and an image forming apparatus including the same.

2. Description of the Related Art Conventionally, according to a sheet conveying device mounted on an image forming apparatus such as a copying machine or a printer, a sheet on which an image is formed is discharged to a discharge tray by a discharge roller provided at a discharge port at the end of the conveying path. There is. Such a sheet conveying device is provided with an actuator and a sensor for detecting the full loading of sheets on the discharge tray.

For example, in Patent Document 1, an actuator having a central detection unit that detects the stacking height of the widthwise central portion of the sheets on the discharge tray and a side detection unit that detects the stacking heights of both ends in the width direction is used. The conventional image forming apparatus is disclosed. According to this configuration, when both ends in the width direction orthogonal to the discharge direction of the discharged sheet are curled upward, that is, in a so-called side curl state, the side detection unit detects before the central detection unit. It

Therefore, the sheet conveying device stops before the side curled portion of the sheet blocks the discharge port, and the leading edge of the succeeding sheet hits the trailing end of the sheet on the discharge tray to prevent the sheet on the discharge tray from being pushed out. To be done.

JP, 2014-166898, A

According to the actuator as described above, when the sheet being conveyed comes into contact with the side detection portion, the conveyance resistance becomes large, which causes scratches on the sheet and sliding contact noise. Even when the actuator of Patent Document 1 is used, this problem may occur when the sheet conveying speed is increased or when the sheet has a large curl. Therefore, the actuator of Patent Document 1 has room for further improvement.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a sheet conveyance device that detects a full load of side curled sheets and that suppresses sheet conveyance resistance. It is also an object to provide an image forming apparatus including the sheet conveying device.

The sheet conveying device of the present invention includes a discharge tray (2B) that supports discharged sheets (S), discharge rollers (82, 83, 84) that discharge the sheets (S) to the discharge tray (2B), and An actuator (86) that is rotatably provided around a moving axis (R) and that contacts the sheet (S) discharged to the discharge tray (2B) and detects the stacking height of the sheet (S); A detection sensor (87) for detecting the position of the actuator (86), and the actuator (86) discharges the discharge roller (82, 83, 84) to the discharge tray (2B) in the width direction orthogonal to the sheet discharge direction. The sheet is discharged to the discharge tray (2B) in the width direction and the central detection portion (862) that can be brought into contact with the central portion of the formed sheet (S) and extends downstream from the rotation axis (R) in the sheet discharging direction. A first side detection unit (863) that is capable of contacting the end of the sheet (S) and extends downstream from the rotation axis (R) in the sheet discharge direction, and the first side detection unit (863) includes: It has a first surface (863C) arranged on the side of the discharge tray (2B), and the central detection portion (862) has a second surface (862C) arranged on the side of the discharge tray (2B), and the width direction The first tip portion (863D) on the first surface (863C) of the first side detection portion (863) is the second tip portion on the second surface (862C) of the central detection portion (862) when viewed in the direction along the It is arranged above the virtual tangent line (T) including (862D).

According to the above configuration, when the sheet discharged to the discharge tray has side curled, the first side detection unit is lifted before the central detection unit.

According to the present invention, by providing the first side detector, it is possible to detect the full load of side curled sheets. In addition, since the first tip of the first side detector is located above the virtual tangent line including the second tip of the central detector, it is possible to prevent the discharged sheet from contacting the first side detector. .. Therefore, the conveyance resistance of the sheet being discharged can be suppressed, and the occurrence of scratches on the sheet and sliding contact noise can be suppressed.

FIG. 3 is a central cross-sectional view of the image forming apparatus of one embodiment. FIG. 3 is a perspective view around a discharge unit of the image forming apparatus. FIG. 4 is a partial front cross-sectional view of the vicinity of a discharge unit of the image forming apparatus. It is a perspective view of an actuator. FIG. 4 is a sectional view taken along line AA of FIG. 3. FIG. 4 is a sectional view taken along line BB of FIG. 3. FIG. 6 is a diagram showing a state in which a sheet is being discharged in FIG. 5. FIG. 7 is a diagram showing a state in which a sheet is being discharged in FIG. 6.

In the following description, the state in which the image forming apparatus 1 is installed so as to be usable as shown in FIGS. 1 and 2 is used as a reference, the side on which the sheet tray 10 is pulled out is the front, and the opposite side is the rear, and the image forming apparatus 1 is defined from the front side in the left-right direction, and the discharge tray 2B side of the image forming apparatus 1 is defined as the upper side, and the opposite side is defined as the lower side.

[Overall configuration of image forming apparatus]
An image forming apparatus 1 shown in FIG. 1 is an embodiment of the image forming apparatus according to the present invention, and includes a housing 2, a supply unit 3, a motor 4, and an image forming unit 5 as an example of an image forming unit. And a discharge unit 8 as an example of a member constituting the sheet conveying apparatus.

The supply unit 3 is arranged below the image forming apparatus 1 and conveys the sheet S held by the supply unit 3 to the image forming unit 5. The image forming unit 5 is arranged downstream of the supply unit 3 in the conveying direction of the sheet S and forms an image on the sheet S conveyed from the supply unit 3. The discharge unit 8 is arranged on the downstream side of the image forming unit 5 in the transport direction of the sheet S, and discharges the sheet S on which an image is formed by the image forming unit 5 to the outside of the image forming apparatus 1.

The supply unit 3 includes a sheet tray 10, a feeding mechanism 20, a transport roller 24, and a registration roller 26.

The sheet tray 10 is detachably attached to a sheet tray attachment portion 2A formed at the bottom of the housing 2. The sheet tray 10 is mounted on the sheet tray mounting portion 2A by being inserted into the sheet tray mounting portion 2A from the front to the rear, and is positioned at the mounting position. Further, the sheet tray 10 is positioned from the mounting position to the pulling position by pulling the sheet tray 10 from the rear side to the front side with respect to the sheet tray mounting portion 2A.

The sheet tray 10 includes a tray main body 11 that can support a plurality of sheets S, a pressure plate 12 that is arranged on the tray main body 11 and that can stack the sheets S, and that can vertically displace the sheets S, and raises the pressure plate 12. And a pressure plate raising member 13 for.

The pressure plate 12 is rotatably supported by a rotation fulcrum 12A, and can be displaced in the vertical direction. The pressure plate lifting member 13 is driven by the motor 4 to lift its tip. The pressure plate 12 is lifted by the lifting of the pressure plate lifting member 13, and the sheets S stacked on the pressure plate 12 are lifted to a feedable position as shown in FIG.

The feeding mechanism 20 is a mechanism that separates the sheets S stacked on the sheet tray 10 one by one, takes them out, and conveys the sheets S toward the conveyance rollers 24. The feeding mechanism 20 includes a pickup roller 21, a separation roller 22, and a separation pad 23.

The pickup roller 21 is a roller for taking out the sheet S that has been raised to the feeding position by the pressure plate 12, and is arranged above the pressure plate 12. The separation roller 22 is arranged on the downstream side of the pickup roller 21 in the conveying direction of the sheet S, and the separation pad 23 is arranged to face the separation roller 22 and is urged toward the separation roller 22.

The sheets S taken out by the pickup roller 21 are sent to the separation roller 22 side, separated one by one between the separation roller 22 and the separation pad 23, and conveyed toward the conveyance roller 24.

The transport roller 24 is a roller that applies a transport force to the sheet S, and is arranged on the downstream side of the sheet feeding mechanism 20 in the transport direction of the sheet S. The sheet S conveyed from the feeding mechanism 20 toward the conveying roller 24 is conveyed toward the registration roller 26.

The registration roller 26 is arranged downstream of the transport roller 24 in the transport direction of the sheet S. The registration roller 26 regulates the movement of the front end of the conveyed sheet S and temporarily stops it, and then conveys it toward a transfer position at a predetermined timing.

The image forming unit 5 includes a process cartridge 50 that transfers an image onto the surface of the sheet S conveyed from the supply unit 3, an exposure unit 60 that exposes the surface of the photosensitive drum 54 of the process cartridge 50, and a process cartridge 50. A fixing unit 70 that fixes the image transferred to the sheet S is provided.

The process cartridge 50 is arranged above the sheet tray mounting portion 2A of the housing 2. The process cartridge 50 includes a developer accommodating chamber 51, a supply roller 52, a developing roller 53, a photosensitive drum 54, and a transfer roller 55.

Toner serving as a developer is stored in the developer storage chamber 51. The toner stored in the developer storage chamber 51 is sent to the supply roller 52 while being stirred by a stirring member (not shown). The supply roller 52 further supplies the toner sent from the developer storage chamber 51 to the developing roller 53.

The developing roller 53 is arranged in close contact with the supply roller 52, and carries the toner supplied from the supply roller 52. A developing bias is applied to the developing roller 53 by a bias applying unit (not shown).

The photosensitive drum 54 is arranged adjacent to the developing roller 53. The surface of the photosensitive drum 54 is uniformly charged by a charger (not shown), and then exposed by the exposure unit 60. The exposed portion of the photosensitive drum 54 has a lower potential than the other portions, and an electrostatic latent image based on image data is formed on the photosensitive drum 54. Then, the charged toner is supplied from the developing roller 53 to the surface of the photosensitive drum 54 on which the electrostatic latent image is formed, so that the electrostatic latent image is visualized and becomes a developer image.

The transfer roller 55 is disposed so as to face the photoconductor drum 54, and a negative transfer bias is applied by a bias applying unit (not shown). While the transfer bias is applied to the surface of the transfer roller 55, the sheet S is conveyed between the photosensitive drum 54 on which the developer image is formed and the transfer roller 55 (transfer position) without being pinched. The developer image formed on the surface of the photosensitive drum 54 is transferred to the surface of the sheet S.

The exposure unit 60 includes a laser diode, a polygon mirror, a lens, and a reflecting mirror, and irradiates the photosensitive drum 54 with laser light based on the image data input to the image forming apparatus 1. Thus, the surface of the photoconductor drum 54 is exposed.

The fixing unit 70 includes a heating roller 71 and a pressing roller 72. The heating roller 71 is rotationally driven by the driving force from the motor 4, and the heating roller 71 is heated by supplying electric power from a power source (not shown). The pressing roller 72 is disposed so as to face the heating roller 71, and closely contacts the heating roller 71 to be drivenly rotated. When the sheet S to which the developer image is transferred is conveyed to the fixing unit 70, the sheet S is conveyed while sandwiching the sheet S between the heating roller 71 and the pressing roller 72, and the developer image is fixed on the sheet S.

The discharge unit 8 includes a discharge mechanism 81 and a discharge port 8A, and discharges the sheet S conveyed from the fixing unit 70 toward the outside of the housing 2. A discharge tray 2B is formed on the upper surface of the housing 2, and the sheets S discharged to the outside of the housing 2 are accumulated on the discharge tray 2B. The discharge unit 8 will be described in detail below.

[Discharge unit]
FIG. 2 is a perspective view around the discharge unit 8 of the image forming apparatus 1. FIG. 3 is a partially sectional front view of the vicinity of the discharge unit 8 of the image forming apparatus 1. FIG. 4 is a perspective view of the actuator 86. 5 is a sectional view taken along the line AA of FIG. 3, FIG. 6 is a sectional view taken along the line BB of FIG. 3, and FIG. 7 is a diagram showing a state in which the sheet S is being discharged in FIG. FIG. 8 is a diagram showing a state in which the sheet S is being discharged in FIG.

The discharge unit 8 includes a discharge mechanism 81, a sheet detection mechanism 85, and a discharge port 8A. The discharge port 8A is an opening formed above the rear end of the discharge tray 2B in the housing 2.

<Discharge mechanism>
The ejection mechanism 81 is a mechanism for ejecting the sheet S conveyed from the fixing unit 70 to the ejection tray 2B through the ejection port 8A. The discharging mechanism 81 includes four sets of a driving roller 82, a first pinch roller 83, and a second pinch roller 84 in the left-right direction. The drive roller 82, the first pinch roller 83, and the second pinch roller 84 are examples of discharge rollers that discharge the sheet S to the discharge tray 2B.

As shown in FIGS. 5 to 8, the drive roller 82 is arranged near the discharge port 8A and above the conveyance path P. The driving force from the motor 4 is input to the driving roller 82. The drive roller 82 forms a nip with the first pinch roller 83 and the second pinch roller 84 to convey the sheet S conveyed along the conveyance path P along the discharge direction.

The first pinch roller 83 is arranged near the discharge port 8A of the housing 2 and below the transport path P. The first pinch roller 83 is arranged below the transport path P at a position facing the drive roller 82. The first pinch roller 83 forms a nip with the driving roller 82, and thereby rotates following the driving roller 82.

The second pinch roller 84 is arranged near the discharge port 8A and below the transport path P. The second pinch roller 84 is arranged below the transport path P at a position facing the drive roller 82. The second pinch roller 84 is arranged downstream of the first pinch roller 83 in the discharging direction. The second pinch roller 84 forms a nip with the drive roller 82, and thereby rotates following the drive roller 82.

In this manner, the first pinch roller 83 and the second pinch roller 84 form a nip with respect to the drive roller 82, so that the sheet S moves around the drive roller 82 by the first pinch roller 83 and the second pinch roller 84. It is conveyed while being pressed along the surface. As a result, the curl of the sheet S is corrected.

<Sheet detection mechanism>
The sheet detection mechanism 85 is a mechanism that detects the full loading of the sheets S on the discharge tray 2B. The sheet detection mechanism 85 includes an actuator 86 and a detection sensor 87. As shown in FIG. 3, the actuator 86 is rotatably provided on the housing 2 about a rotation axis R, and contacts the sheet S discharged onto the discharge tray 2B to increase the stacking height of the sheet S. It is a member to detect. As shown in FIG. 6, the detection sensor 87 is a sensor that is provided inside the housing 2 on the left side of the actuator 86 and detects the position of the actuator.

As shown in FIG. 4, the actuator 86 includes a rotation shaft portion 861, a central detection portion 862 that detects the stacking height of the left and right central portions of the sheet S on the discharge tray 2B, and a stacking height of the left end portion of the sheet S. The first side detection unit 863 that detects the height, the second side detection unit 864 that detects the stacking height of the right end portion of the sheet S, and the light shielding unit 865. The actuator 86 of this embodiment is integrally formed of resin. Thereby, the dimensional accuracy of the actuator 86 is improved and the actuator 86 can be manufactured at low cost.

The rotating shaft portion 861 is a rod-shaped member that extends in the left-right direction with the rotating shaft center R as the shaft center. The rotating shaft portion 861 is formed longer than the width of the discharge tray 2B in the left-right direction. The central detecting portion 862 is provided at the substantially central portion of the rotating shaft portion 861 and at the central position of the discharged sheet S in the left-right direction. The center detecting portion 862 extends from the rotating shaft portion 861 to the downstream side in the sheet discharge direction, and is formed so as to be able to contact the central portion of the sheet S discharged onto the discharge tray 2B.

As shown in FIG. 5, the central detector 862 has a third arm portion 862A, a fourth arm portion 862B, a second surface 862C, and a second tip portion 862D. The third arm portion 862A is a plate-shaped member that extends forward from the rotating shaft portion 861 and has a left-right length that is shorter than a left-right length of the first side detection portion 863.

The fourth arm portion 862B is a plate-shaped member that is bent from the tip end portion of the third arm portion 862A and extends in a direction closer to the discharge tray 2B than the third arm portion 862A, that is, in the front lower direction. It is formed to have the same width as the portion 862A. The second surface 862C is the back surface of the fourth arm portion 862B, and is the surface with which the leading end portion of the discharged sheet S abuts. Although the second surface 862C is a flat surface in this embodiment, it may be a curved surface.

The second leading end portion 862D is a leading end portion on the lower end side of the second surface 862C, and is a portion that comes into contact with the sheets S loaded in the discharge tray 2B. The second leading end portion 862D is arranged at a predetermined distance or more in front of the rear end portion of the discharge tray 2B so that the sheet S discharged to a distance on the discharge tray 2B can be detected.

In the case where the central detecting portion 862 is integrally rotated with the rotating shaft portion 861, the second leading end portion 862D is not in contact with the sheet S on the discharge tray 2B, and the sheet S is not being discharged. Can be displaced between the initial position (the position shown in FIG. 5) located at the second position and the discharge position (the position shown in FIG. 7) in the state where the second leading end portion 862D is pushed up by the discharging sheet S. Then, between the initial position and the discharge position, the second leading end portion 862D contacts the sheet S loaded on the discharge tray 2B and is pushed up by a predetermined amount (indicated by a chain double-dashed line in FIG. 7). Position).

As shown in FIG. 6, the first side detection unit 863 includes a first arm portion 863A, a second arm portion 863B, a first surface 863C, and a first tip portion 863D. The first arm portion 863A is a plate-shaped member that extends forward from the rotating shaft portion 861 at the same angle as the third arm portion 862A, and the length in the left-right direction is greater than the length in the left-right direction of the third arm portion 862A. It is formed long.

The second arm portion 863B is bent from the tip end portion of the first arm portion 863A, and extends in a direction away from the discharge tray 2B with respect to the first arm portion 863A, that is, in a direction closer to horizontal than the first arm portion 863A. The first arm portion 863A has the same width as the first arm portion 863A. The first surface 863C is the back surface of the second arm portion 863B, and is a surface that makes it difficult for the leading end portion of the discharged sheet S to contact. Although the first surface 863C is a flat surface in the present embodiment, it may be a curved surface.

The first leading end portion 863D is a leading end portion on the lower end side of the first surface 863C, and is a portion that can come into contact with the left end portion of the sheet S discharged onto the discharge tray 2B. The first leading end portion 863D is arranged forward by a predetermined distance or more from the rear end portion of the discharge tray 2B so that the sheet S discharged to a distance on the discharge tray 2B can be detected.

Further, as viewed in the left-right direction as shown in FIG. 5, the first tip portion 863D is disposed above the virtual tangent line T including the second tip portion 862D on the second surface 862C of the central detection portion 862. There is. The virtual tangent line T is a line along the second surface 862C when the second surface 862C is not a curved surface but a flat surface as in the present embodiment.

The first side detection unit 863 as described above integrally rotates with the rotation shaft unit 861 and the central detection unit 862. The first side detection unit 863 has an initial position (position shown in FIG. 6) which is located when the central detection unit 862 is not in contact with the sheet S on the discharge tray 2B and the sheet S is not being discharged, and a center position. The detection unit 862 can be displaced between the discharge position (the position shown in FIG. 8) in a state in which the detection unit 862 is pushed up by the discharging sheet S.

Then, between the initial position and the discharge position, the first leading end portion 863D comes into contact with the side curled sheet S on the discharge tray 2B and is pushed up by a predetermined amount (indicated by a two-dot chain line in FIG. 8). Position). The side curl here refers to a state in which the left and right ends of the discharged sheet S are curled upward, like the sheet S indicated by a two-dot chain line in FIG.

As shown in FIG. 4, the second side detection unit 864 is provided on the opposite side to the first side detection unit 863 in the left-right direction with the central detection unit 862 interposed therebetween. The second side detection unit 864 has the same shape as the first side detection unit 863. That is, the second side detection unit 864 includes a fifth arm portion 864A corresponding to the first arm portion 863A, a sixth arm portion 864B corresponding to the second arm portion 863B, and a third surface corresponding to the first surface 863C. 864C and a third tip portion 864D corresponding to the first tip portion 863D.

Like the first side detecting unit 863, the second side detecting unit 864 as described above integrally rotates with the rotating shaft unit 861 and the central detecting unit 862, and can be displaced between the initial position and the discharge position. Is. There is a full load position between the initial position and the discharge position.

The light shielding portion 865 is provided near the right end portion of the rotating shaft portion 861. The light shielding portion 865 is a plate-shaped member extending forward from the rotating shaft portion 861 and has a light shielding plate 865A at the tip. The light blocking portion 865 rotates integrally with the central detection portion 862, the first side detection portion 863, and the second side detection portion 864.

In the light-shielding portion 865, the light-shielding plate 865A is located between the detection sensors 87 and the detection position (the position indicated by the chain double-dashed line in FIG. 8) detected by the detection sensor 87, and the light-shielding plate 865A is below the detection sensor 87 or It can be displaced between a non-detection position which is located above and is not detected by the detection sensor 87 (a position indicated by a broken line in FIG. 6 or 8). That is, the position of the light shielding plate 865A when the central detection unit 862, the first side detection unit 863, or the second side detection unit 864 is at the full load position is the detection position.

The detection sensor 87 is an optical sensor such as a photo interrupter. The detection sensor 87 detects whether the light is blocked or not blocked by the light blocking plate 865A. The detection result is input to a control unit (not shown). When the light shield plate 865A is in the non-detection position, the control unit determines that the sheets S on the discharge tray 2B are not full, while when the light shield plate 865A is in the detection position for a predetermined time or longer, the sheets on the discharge tray 2B are not detected. It is determined that S is full. The predetermined time period here is a time period in which the central detecting portion 862 is pushed up by the sheet S being discharged.

According to the sheet detection mechanism 85 having such a configuration, when the sheet S discharged onto the discharge tray 2B is side-curled, the first side detection section 863 or the second side detection section 864 is provided before the central detection section 862. Is lifted (see FIG. 8). That is, by providing the first side detection unit 863 and the second side detection unit 864, it is possible to detect the full load of the side curled sheet S.

According to the sheet detection mechanism 85 described above, the first tip portion 863D of the first side detection portion 863 and the third tip portion 864D of the second side detection portion 864 include the second tip portion 862D of the central detection portion 862. It is located above the tangent line T (see FIG. 5). As a result, it is possible to prevent the discharged sheet S from coming into contact with the first side detection unit 863 or the second side detection unit 864 (see FIG. 8 ). Therefore, the conveyance resistance of the sheet S being discharged can be suppressed, and the scratches on the sheet S and the generation of sliding contact noise can be suppressed.

According to the actuator 86 described above, since the fourth arm portion 862B of the central detection portion 862 is bent in the direction toward the discharge tray 2B, the discharged sheet S is close to a right angle with respect to the fourth arm portion 862B. Contact at an angle (see the chain double-dashed line in FIG. 7). Therefore, since the actuator 86 can be lifted with a small force, the actuator 86 can be lifted even with a weak seat S.

According to the above actuator 86, the second surface 862C with which the sheet S abuts is a flat surface, so that the flat second surface 862C can be used even when the sheet S with weak stiffness cannot lift the central detection unit 862. The seat S is guided along. Therefore, compared to the case where the second surface 862C is formed of a curved surface such as an arc shape, it is possible to prevent the sheet S from curling up and being rolled up on the discharge tray 2B (see FIG. 7).

According to the actuator 86 described above, the conveyance resistance of the sheet S is reduced by forming the central detection unit 862 to have a short length in the left-right direction (see FIG. 4 ). Further, since the central detecting portion 862 becomes lighter, the moment becomes smaller and the conveyance resistance of the sheet S becomes smaller.

According to the actuator 86 described above, the second arm portion 863B bends upward with respect to the first arm portion 863A of the first side detection portion 863, and the second arm portion 863B is bent relative to the fifth arm portion 864A of the second side detection portion 864. Since the 6-arm portion 864B is bent upward, when the first side detecting portion 863 and the second side detecting portion 864 rotate upward, the eaves portion 2C of the housing 2 located above the actuator 86. You can avoid interfering with.

Further, since the first side detection unit 863 and the second side detection unit 864 are longer and heavier than the non-bent form, the moment is increased and the force for pressing the sheet S discharged onto the discharge tray 2B is increased. Therefore, the side curl of the sheet S can be reduced.

According to the above-described actuator 86, by having the second side detecting portion 864 on the opposite side of the first side detecting portion 863 across the central detecting portion 862 in the left-right direction, both end portions of the sheet S can be detected. Detection accuracy is improved.

The rotating shaft portion 861 is viewed in the left-right direction as shown in FIG. 6, and is in the front-back direction that is the sheet conveying direction with the discharge roller (driving roller 82, the first pinch roller 83 or the second pinch roller 84). You may arrange|position so that the rotating shaft center R may be located in the position which overlaps. As a result, the moment of rotation of the actuator 86 becomes small, and the conveyance resistance of the sheet S at the time of discharge becomes small.

[Sheet full load detection operation]
When the sheet S is conveyed to the ejection mechanism 81 in the state shown in FIGS. 5 and 6, the drive roller 82, the first pinch roller 83, and the second pinch roller 84 eject the sheet S from the ejection port 8A. The sheet S discharged from the discharge port 8A is discharged to the discharge tray 2B while pushing up the central detecting portion 862 at the initial position to the discharge position (the position shown in FIG. 7).

At this time, the light shielding portion 865 of the actuator 86 moves from the non-detection position (the position indicated by the broken line in FIG. 6) to the non-detection position (the position indicated by the alternate long and two short dashes line in FIG. 8) from the non-detection position when the sheet S is being discharged. When the sheet S is discharged, the sheet returns from the non-detection position to the non-detection position through the detection position. Based on the signal from the detection sensor 87, the control unit determines that the sheets S on the discharge tray 2B are not full, based on the state in which the sheets S are being detected for less than the predetermined time.

When the left and right center portions of the sheet S on the discharge tray 2B reach the full load position F1 (see FIG. 7) by repeating the discharge of the sheet S, the central detecting unit 862 moves to the full load position (the position indicated by the chain double-dashed line in FIG. 7). It will be lifted up to. In this state, the light-shielding portion 865 is located at the detection position (the position indicated by the chain double-dashed line in FIG. 8), and the signal from the detection sensor 87 causes the control portion to detect the predetermined time or more, and accordingly, the discharge tray 2B is placed on the discharge tray 2B. The sheet S is determined to be full.

When determining that the sheets S are full, the control unit controls to stop printing. As a result, the discharge of the sheet S is stopped before the sheet S blocks the discharge port 8A, so that the rear end of the sheet S on the discharge tray 2B is hit by the leading edge of the succeeding sheet S and the sheet S on the discharge tray 2B is removed. Extrusion is suppressed.

On the other hand, the side curled sheet S is repeatedly discharged, and the left end portion or the right end portion of the sheet S reaches the full load position F2 (FIG. 8) before the left and right center portions of the sheet S on the discharge tray 2B reach the full load position F1. (Refer to FIG. 8), the first side detection unit 863 or the second side detection unit 864 is in a state of being lifted to the full load position (the position indicated by the chain double-dashed line in FIG. 8). In this state, the light shielding unit 865 is located at the detection position, and the control unit determines that the sheet S on the discharge tray 2B is full, based on the signal from the detection sensor 87 being in the detection state for a predetermined time or longer.

When determining that the sheets S are full, the control unit controls to stop printing. As a result, the discharge of the sheet S is stopped before the side curled sheet S blocks the discharge port 8A, so that the trailing edge of the sheet S on the discharge tray 2B is hit by the leading edge of the succeeding sheet S and the discharge tray 2B is discharged. Extrusion of the upper sheet S is suppressed.

[Effect of Embodiment]
The sheet conveying device mounted on the image forming apparatus 1 described above includes a discharge tray 2B that supports the discharged sheet S, and a discharge roller (driving roller 82, first pinch roller 83, or the like) that discharges the sheet S to the discharge tray 2B. A second pinch roller 84). Further, the sheet conveying device is provided so as to be rotatable around a rotation axis R, and an actuator 86 that detects the stacking height of the sheets S by contacting the sheets S discharged onto the discharge tray 2B. And a detection sensor 87 for detecting the position. The actuator 86 is capable of contacting the central portion of the sheet S discharged onto the discharge tray 2B in the width direction orthogonal to the sheet discharging direction of the discharging roller, and extends from the rotation axis R to the downstream side in the sheet discharging direction. 862. Further, the actuator 86 includes a first side detection unit 863 that is capable of contacting the end portion of the sheet S discharged onto the discharge tray 2B in the width direction and that extends from the rotation axis R to the downstream side in the sheet discharge direction. The first side detection unit 863 has a first surface 863C arranged on the side of the discharge tray 2B. The central detection unit 862 has a second surface 862C arranged on the side of the discharge tray 2B. When viewed in the direction along the width direction, the first tip portion 863D on the first surface 863C of the first side detection portion 863 includes the virtual tangent line T including the second tip portion 862D on the second surface 862C of the central detection portion 862. It is located above.

With this configuration, when the sheet S discharged onto the discharge tray 2B is side-curled, the first side detection unit 863 is lifted before the central detection unit 862. That is, by providing the first side detection unit 863, it is possible to detect the full load of the side curled sheet S. Further, since the first front end portion 863D of the first side detection portion 863 is located above the virtual tangent line T including the second front end portion 862D of the central detection portion 862, the sheet S being ejected has the first side detection portion 863. It is possible to suppress contact with. Therefore, the conveyance resistance of the sheet S being discharged can be suppressed, and the scratches on the sheet S and the generation of sliding contact noise can be suppressed.

Further, according to the above-described sheet conveying device, the first side detecting portion 863 is bent from the first arm portion 863A extending from the rotation axis R and the tip end portion of the first arm portion 863A, and is bent from the first arm portion 863A. Also extends in a direction away from the discharge tray 2B and has a second arm portion 863B including a first surface 863C.

According to this configuration, the second arm portion 863B is bent upward with respect to the first arm portion 863A, so that when the first side detection portion 863 rotates upward, it is positioned above the actuator 86. It is possible to avoid interference with the eaves portion 2C of the housing 2. Further, since the first side detection portion 863 becomes longer and heavier than the non-bent form, the moment becomes large and the force for pressing the sheet S discharged onto the discharge tray 2B becomes large. Therefore, the side curl of the sheet S can be reduced.

Further, according to the above-described sheet conveying device, the central detection portion 862 is bent from the third arm portion 862A extending from the rotation axis R and the tip end portion of the third arm portion 862A, and is discharged from the third arm portion 862A. It has a fourth arm portion 862B including a second surface 862C that extends in a direction approaching the tray 2B and that a leading end portion of the discharged sheet S contacts.

With this configuration, since the fourth arm portion 862B is bent in the direction approaching the discharge tray 2B, the discharged sheet S contacts the fourth arm portion 862B at an angle close to a right angle. Therefore, since the actuator 86 can be lifted with a small force, the actuator 86 can be lifted even with a weak seat S.

Further, according to the above-described sheet conveying device, the second surface 862C of the fourth arm portion 862B is a flat surface.

According to this configuration, since the surface with which the sheet S abuts is a flat surface, the sheet S moves along the flat second surface 862C even when the weak sheet S cannot lift the central detection unit 862. Be guided. Therefore, as compared with the case where the second surface 862C is formed of a curved surface such as an arc shape, it is possible to suppress the sheet S from curling up and being rolled up on the discharge tray 2B.

Further, according to the above-described sheet conveying device, the central detection portion 862 is formed such that the widthwise length thereof is shorter than the widthwise length of the first side detection portion 863.

According to this configuration, the conveyance resistance of the sheet S is reduced by forming the center detection unit 862 to have a short width in the width direction. Further, since the central detecting portion 862 becomes lighter, the moment becomes smaller and the conveyance resistance of the sheet S becomes smaller.

Further, according to the above-described sheet conveying device, the rotation axis R is arranged at a position overlapping the discharge roller in the sheet conveying direction when seen in the direction along the width direction.

With this structure, the moment of rotation of the actuator 86 is reduced, and the conveyance resistance of the sheet S is reduced.

Further, according to the above-described sheet conveying device, the actuator 86 has the second side detection unit 864 in the width direction on the side opposite to the first side detection unit 863 with the central detection unit 862 interposed therebetween.

According to this configuration, the detection accuracy is improved by detecting both ends of the sheet S.

Further, according to the above-described sheet conveying device, the actuator 86 is integrally formed of resin.

With this configuration, the dimensional accuracy of the actuator 86 is improved and the actuator 86 can be manufactured at low cost.

1 image forming apparatus 2B discharge tray 5 image forming unit (image forming section)
82 Drive roller (discharge roller)
83 1st pinch roller (discharge roller)
84 Second pinch roller (discharge roller)
86 Actuator 87 Detection sensor 862 Central detection portion 862A Third arm portion 862B Fourth arm portion 862C Second surface 862D Second tip portion 863 First side detection portion 863A First arm portion 863B Second arm portion 863C First surface 863D Second 1 Tip 864 Second side detector R Rotation axis S Seat T Virtual tangent

Claims (9)

A discharge tray that supports the discharged sheets,
A discharge roller that discharges a sheet to the discharge tray,
An actuator that is rotatably provided around a rotation axis and that detects the stacking height of sheets by contacting the sheets discharged to the discharge tray,
A detection sensor for detecting the position of the actuator,
The actuator is
A central detection unit that is capable of contacting the central portion of the sheet discharged onto the discharge tray in the width direction of the discharge roller that is orthogonal to the sheet discharge direction, and that extends from the rotation axis toward the downstream side in the sheet discharge direction;
A first side detection unit that is capable of contacting an end portion of the sheet discharged to the discharge tray in the width direction and that extends from the rotation axis toward the downstream side in the sheet discharge direction;
The first side detector has a first surface arranged on the side of the discharge tray,
The central detection unit has a second surface arranged on the discharge tray side,
When viewed in the direction along the width direction, the first tip end portion of the first surface of the first side detector is located above a virtual tangent line including the second tip end portion of the second surface of the central detector. A sheet conveying device, which is arranged. The first side detector is
A first arm portion extending from the rotation axis;
It has a 2nd arm part which bends from the front-end|tip part of the said 1st arm part, is extended in the direction which separates with respect to the said discharge tray rather than the said 1st arm part, and has the said 1st surface. 1. The sheet conveying device according to 1. The central detector is
A third arm portion extending from the rotation axis,
A fourth arm portion including the second surface that is bent from the tip end portion of the third arm portion, extends in a direction closer to the discharge tray than the third arm portion, and is in contact with the tip end portion of the discharged sheet. The sheet conveying device according to claim 1 or 2, further comprising: The sheet conveying device according to claim 3, wherein the second surface of the fourth arm portion is a flat surface. 5. The center detection unit is formed such that the length in the width direction is shorter than the length in the width direction of the first side detection unit. Sheet conveying device. The rotation axis is arranged at a position overlapping the discharge roller in the sheet conveying direction when viewed in the direction along the width direction. Sheet transport device. The said actuator has a 2nd side detection part on the opposite side to the said 1st side detection part on both sides of the said center detection part in the said width direction, The any one of Claim 1 to 6 characterized by the above-mentioned. The sheet conveying apparatus according to item 1. The sheet conveying device according to claim 1, wherein the actuator is integrally formed of resin. A sheet conveying device according to any one of claims 1 to 8,
An image forming apparatus, comprising: an image forming unit which is arranged on an upstream side of the discharge roller in a sheet conveying direction and which forms an image on a sheet.

Images