JP2010155681A - Sheet ejecting device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet ejecting device and an image forming device, capable of ejecting a sheet, regardless of the kind of the sheet, without lowering a stacking characteristic. <P>SOLUTION: Second and third detecting levers 52 and 53 rotating upward by abutting on both side ends in the width direction of the sheet ejected by a sheet ejecting means, are arranged on the upstream side in the ejecting direction of a first detecting lever 51 for pressing a central part in the width direction of the sheet ejected to a stacking tray 33. When ejecting the sheet, both side ends in the width direction of the sheet are curved so that the sheet S becomes lower in both ends than the central part by pressing sheet both ends by the second and third detecting levers 52 and 53, and when the second and third detecting levers 52 and 53 abutting on the sheet rotate upward, the first detecting lever 51 is rotated upward via an interlocking part. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a sheet discharging apparatus and an image forming apparatus, and more particularly, to a configuration of a pressing unit that presses sheets stacked on a sheet stacking unit from above.

  Conventionally, in an image forming apparatus such as a printer, a facsimile machine, a copying machine, a multifunction printer, etc., a sheet discharging unit discharges a sheet on which an image is formed by a sheet discharging unit and stacks the sheet on a sheet stacking unit provided below the sheet discharging unit. Equipment.

  In such an image forming apparatus, when an image is formed on a sheet, a toner image is formed on a photosensitive drum, the toner image is transferred onto the sheet, and then the toner image is fixed on the sheet. Yes. After fixing the toner image on the sheet in this way, the sheet is discharged from the sheet discharge port to a stacking tray as a sheet stacking unit by a pair of discharge rollers provided in the sheet discharge apparatus. The stacking tray is inclined upward as it goes downstream in the sheet discharging direction in order to ensure alignment performance due to the weight of the discharged sheets.

  Further, in the conventional image forming apparatus, in order to detect the amount of sheets stacked on the stacking tray, for example, according to the amount of sheets while contacting the central portion in the width direction orthogonal to the sheet discharging direction of the stacked sheets. In some cases, a loading amount detection member that moves is provided. Then, if it is detected that the stacking amount of the sheet has reached a predetermined amount by the movement amount of the stacking amount detection member, the sheet on the stacking tray falls from the stacking tray or a jam occurs by stopping printing. To prevent it.

  Here, when the sheet stacking amount is detected, for example, when both end portions in the width direction of the sheet are curled upward, the stacking amount detection member cannot accurately detect the sheet stacking amount. For this reason, conventionally, by increasing the length in the width direction of the stacking amount detection member, the weight is increased and the curling of the sheet is suppressed.

  However, when the discharged sheet comes into contact with the stacking amount detection member whose width in the width direction is increased in this way, a sheet with particularly weak stiffness or a sheet with a curled end in the width direction is a stacking amount detection member. When it comes into contact with the sheet, the sheet may be bent.

  For this reason, in the conventional sheet discharging apparatus, the central sheet pressing member that presses the center in the width direction of the sheet and the side end sheet pressing member that presses the side edge of the sheet on both sides in the width direction of the central sheet pressing member are divided. (See Patent Document 1). When the sheet comes into contact with the central sheet pressing member, the side edge sheet pressing member is rotated integrally with the central sheet pressing member, thereby preventing the sheet from being bent.

JP 2007-204228 A

  However, in such a conventional sheet discharging apparatus and an image forming apparatus equipped with the same, the central sheet pressing member is positioned upstream of the side end sheet pressing members at both ends in the discharging direction. The leading edge of the sheet first contacts the center of the sheet pressing member. At this time, a downward force is applied to the sheet by the central sheet pressing member, so that if the sheet is a weak sheet such as thin paper, the sheet hangs down as the sheet advances.

  In this case, there is no problem if the stackable capacity of the stacking tray is small. However, if the inclination of the stacking tray is increased in order to increase the stackable capacity, the hanging sheet will be rounded on the stacking tray. Decreases. Further, even when the sheet is not rounded, the leading edge of the sheet comes into contact with the already discharged sheet at a large angle, so that the stacking state of the sheet that has already been discharged on the stacking tray is disturbed. Sheet stackability is reduced.

  Therefore, the present invention has been made in view of such a current situation, and provides a sheet discharge apparatus and an image forming apparatus that can discharge sheets without deteriorating stackability regardless of the type of sheets. It is for the purpose.

  The present invention provides a sheet discharge apparatus comprising: a sheet discharge unit that discharges a sheet to the sheet stacking unit; and a pressing unit that presses the sheet discharged to the sheet stacking unit from above. A central pressing member that can rotate in the vertical direction that holds the central portion in the width direction orthogonal to the discharging direction of the sheet discharged by the means, and a vertical rotation that contacts the sheets discharged on both sides of the central pressing member And a free side end pressing member, and when discharging the sheet, both ends of the discharged sheet are pressed by the side end pressing member on the upstream side in the discharging direction from the central pressing member. Is.

  According to the present invention, at the time of discharging, the sheet is curved so that both ends are lower, and when the side end pressing member is rotated upward, the central pressing member is rotated upward, thereby Regardless of the type, the sheet can be discharged without deteriorating the stackability.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a diagram illustrating a configuration of an electrophotographic color printer which is an example of an image forming apparatus including a sheet discharging apparatus according to the first embodiment of the present invention. Reference numeral 1 denotes a color printer, 1A denotes a color printer main body (hereinafter referred to as a printer main body), 1B denotes an image forming unit that forms an image on a sheet, 1C denotes a sheet conveying device, 1D denotes a sheet discharge device, and 31 denotes a fixing unit.

  The image forming unit 1B includes the scanner unit 4 and four process cartridges 2 (2Y, 2M, and 4) that form toner images of four colors of yellow (Y), magenta (M), cyan (C), and black (Bk). 2C, 2Bk). The image forming unit 1B includes an intermediate transfer unit 9 disposed above the process cartridge 2.

  Each process cartridge 2 includes a photosensitive drum 3 (3Y, 3M, 3C, 3Bk) that is an image carrier that forms a toner image. Each photosensitive drum 3 is rotatably supported at both ends by a support member, and is rotated clockwise by transmitting a driving force from a driving motor (not shown) to one end. Is done.

  The intermediate transfer unit 9 includes an intermediate transfer belt 5 wound around a driving roller 6, a tension roller 7a, and a driven roller 7b. The intermediate transfer unit 9 includes a primary transfer roller 8 that is provided inside the intermediate transfer belt 5 and abuts against the intermediate transfer belt 5 at a position facing the photosensitive drum 3.

  Here, the intermediate transfer belt 5 is composed of a film-like member and is disposed so as to be in contact with each photosensitive drum 3, and is driven in a direction indicated by an arrow (counterclockwise) by a driving roller 6 driven by a driving unit (not shown). It is designed to rotate. Then, by applying a positive transfer bias to the intermediate transfer belt 5 by the primary transfer roller 8, each color toner image having a negative polarity on the photosensitive drum is sequentially transferred to the intermediate transfer belt 5 in a multiple transfer manner. As a result, a full-color image is formed on the intermediate transfer belt.

  A secondary transfer roller 30 constituting a secondary transfer unit that transfers a full color image formed on the intermediate transfer belt to the sheet S is provided at a position facing the drive roller 6 of the intermediate transfer unit 9. . The sheet conveying apparatus 1C conveys the sheet to the secondary transfer unit.

  A fixing unit 31 is disposed above the secondary transfer roller 30, and a discharge roller pair 32 and a double-side reversing unit 40 are disposed above the fixing unit 31. The double-side reversing unit 40 includes a reversing roller pair 41 that is a sheet reversing conveyance roller capable of normal reversing and a switching member 42. As will be described later, the sheet reversed by the double-side reversing unit 40 is again conveyed to the secondary transfer unit by the sheet conveying apparatus 1C.

  In FIG. 1, R1 forms an image on the back side (second side) of the sheet on which the image is formed on one side (first side) by the image forming unit 1B. It is a re-conveyance path as a sheet conveyance path for guiding to the section 1B. The re-conveying path R1 is provided with a re-feed roller pair 43 constituting the sheet conveying apparatus 1C.

  Next, an image forming operation of the full color laser beam printer 1 configured as described above will be described.

  When the image forming operation is started, the scanner unit 4 first irradiates a laser beam (not shown) based on image information from a personal computer (not shown), and the surface is uniformly charged with a predetermined polarity and potential. The surface of the body drum 3 is sequentially exposed to form an electrostatic latent image on the photoreceptor drum. Thereafter, the electrostatic latent image is developed with toner and visualized.

  For example, first, the photosensitive drum 3Y is irradiated with laser light based on an image signal of a yellow component color from the scanner unit 4 to form a yellow electrostatic latent image on the photosensitive drum 3Y. The yellow electrostatic latent image is developed with yellow toner from a developing device, and visualized as a yellow toner image.

  Next, when the toner image arrives at the primary transfer portion where the photosensitive drum 3Y and the intermediate transfer belt 5 come into contact with the rotation of the photosensitive drum 3Y, the primary transfer bias applied to the primary transfer roller 8 causes the toner image. Then, the yellow toner image on the photosensitive drum is transferred to the intermediate transfer belt 5.

  Next, when the portion of the intermediate transfer belt 5 carrying the yellow toner image moves, the magenta toner image formed on the photosensitive drum 3M by the same method as described above is transferred from the yellow toner image to the intermediate transfer belt. 5 is transferred. Similarly, as the intermediate transfer belt 5 moves, a cyan toner image and a black toner image are transferred onto the yellow toner image and the magenta toner image in a primary transfer portion. As a result, a full-color toner image is formed on the intermediate transfer belt.

  In parallel with the toner image forming operation, the sheet S stored in the paper feed cassette 10 is sent out by the pickup roller 11. Thereafter, the sheet S is separated one by one by a separation unit constituted by the pickup roller 11 and the separation roller 12 and conveyed to the registration roller pair 15 through the conveyance roller pair 13 and the intermediate conveyance roller pair 14. .

  At this time, the registration roller pair 15 is stopped. The sheet is brought into contact with the nip portion of the registration roller pair 15 in such a stopped state, and a loop is formed on the sheet so that the sheet S is skewed. It can be corrected.

  Next, after correcting the skew of the sheet S in this way, the registration roller pair 15 is driven at a timing at which the position of the sheet S is aligned with the full-color toner image on the intermediate transfer belt in the secondary transfer unit. As a result, the sheet S is conveyed to the secondary transfer unit, and the full-color toner image is collectively transferred onto the sheet S by the secondary transfer bias applied to the secondary transfer roller 30 in the secondary transfer unit.

  Next, the sheet S on which the full-color toner image has been transferred in this manner is conveyed to the fixing unit 31, and the toner of each color is melted and mixed by receiving heat and pressure in the fixing unit 31, so that a full-color image is formed on the sheet S. It is fixed. Thereafter, the sheet S on which the image is fixed in this manner is discharged to the stacking tray 33 by a discharge roller pair 32 provided downstream of the fixing unit 31.

  On the other hand, when images are formed on both sides of a sheet, first, the switching member 42 of the double-side reversing unit 40 is rotated clockwise by a drive mechanism such as a solenoid (not shown) so that the sheet conveyance path is moved from the opposite side of the sheet discharge roller. Change to the reverse side. Thus, the sheet S on which an image is formed on one side is guided to the reverse roller pair 41 and is conveyed by a predetermined amount in the direction of the stacking tray 33 by the reverse roller pair 41.

  Next, after the sheet S is conveyed by a certain amount in this way, the reversing roller pair 41 is rotated in the reverse direction, whereby the sheet S enters the reconveying path R1. It reaches the merging point with the sheet conveyance path R2. Thereafter, the sheet S is conveyed to the secondary transfer roller 30 through the intermediate conveyance roller pair 14 and the registration roller pair 15, and the image is transferred to the back surface by the secondary transfer roller 30 as the secondary transfer portion.

  By this time, the switching member 42 has been switched to the position for switching the sheet conveyance path shown in FIG. 1 to the discharge roller pair 32 side. As a result, the sheet S on which the image is fixed on the back surface by the fixing unit 31 is stacked on the stacking tray 33 via the discharge roller pair 32.

  FIG. 2 is a perspective view of the sheet discharging apparatus 1D. As shown in FIG. 2, the stacking tray 33 as the sheet stacking unit is inclined so that the downstream side in the sheet discharging direction is higher. As a result, when the sheet S after image formation is discharged onto the stacking tray 33 by the discharge roller pair 32 serving as a sheet discharge unit, the discharged sheet S slides on the stacking tray 33 by its own weight, and moves to the rear end wall 34. It is loaded in the butted state.

  Incidentally, a first detection lever 51, a second detection lever 52, and a third detection lever 53 for detecting the stacking amount of the sheets stacked on the stacking tray 33 are rotatable in the vicinity of the discharge port to the stacking tray 33. Is provided.

  Here, the first detection lever 51 includes three contact portions 51a to 51c that contact a central portion in the width direction orthogonal to the sheet discharge direction of the sheet discharged by the discharge roller pair 32, and a main body extending in the width direction. Part 51e. The first detection lever 51 constitutes a central pressing member that presses the central portion in the width direction of the sheets discharged to the stacking tray 33 by the three contact portions 51a to 51c. , The central contact portion 51b is located at the center of the sheet width.

  The second detection lever 52 includes a contact portion 52 a that contacts one end of the sheet in the width direction and the contact portions 51 a to 51 c of the first detection lever 51 on the upstream side in the discharge direction, and the first detection lever 51. A main body portion 52b extending below the main body portion 51e. The third detection lever 53 includes an abutting portion 53 a that abuts on the other end portion in the width direction of the sheet and an abutting portion 51 a to 51 c of the first detection lever 51 on the upstream side in the discharge direction, and a main body portion of the first detection lever 51. And a main body portion 53b extending below 51e.

  The second and third detection levers 52 and 53 constitute side end pressing members that abut on both side ends in the width direction of the sheet discharged by the discharge roller pair 32 and rotate upward. is there. The first detection lever 51 and the second and third detection levers 52 and 53 constitute a pressing unit 50 that detects the stacking amount of sheets and presses the sheets stacked on the stacking tray 33. .

  The contact portion 52a of the second detection lever 52 and the contact portion 53a of the third detection lever 53 are positioned below the contact portions 51a to 51c of the first detection lever 51, and the first detection lever 51 It is located upstream of the contact portions 51a to 51c in the discharge direction. Further, the main body portions 52 b and 53 b of the second and third detection levers 52 and 53 are arranged below the main body portion 52 b of the first detection lever 51 without overlapping.

  By configuring the main body portions 51e, 52b, and 53b of the first to third detection levers 51 to 53 as described above, the second and third detection levers 52 and 53 are interlocked with the upward rotation as described later. Thus, an interlocking portion that rotates the first detection lever 51 upward is configured.

  Further, the first to third detection levers 51 to 53 have tips of respective contact portions of all of the first to third detection levers 51 to 53 with respect to the rotation center shaft 55 that is the same (common) rotation center. Is rotatably attached so as to come into contact with the upper surface of the discharged sheet. In addition, by attaching the first to third detection levers 51 to 53 to the same rotation center shaft 55 in such a manner that the first to third detection levers 51 to 53 can be rotated in the vertical direction, the design becomes simple and the apparatus can be downsized. .

  With this configuration, when the sheet is discharged from the discharge roller pair 32, first, the leading end of the sheet comes into contact with the contact portions 52a and 53a of the second and third detection levers 52 and 53. Here, when the sheet abuts, the second and third detection levers 52 and 53 are pressed by the sheet and rotate upward. Accordingly, the main body 51e of the first detection lever 51 disposed above the second and third detection levers 52, 53 is pressed by the main bodies 52b, 53b of the second and third detection levers 52, 53. As a result, the first detection lever 51 rotates upward.

  A detected portion 51d is provided at one end of the first detection lever 51. When the first detection lever 51 rotates in this way, the detected portion 51d shields the light transmission type sensor 54 from light. . As a result, the first detection lever 51 as the load amount detection member is detected, and this first detection lever detection signal is input to a control unit (not shown). Then, the control unit detects the sheet stacking amount based on the first detection lever detection signal, that is, the rotation position of the first detection lever 51, and in this embodiment, detects the full sheet load and stops the image forming operation. And stop discharging the sheet.

  Next, the operation of the first to third detection levers 51 to 53 when the sheet discharge device stacks sheets will be described with reference to FIG. FIG. 3 is a cross-sectional view of the full-color laser beam printer 1 when a sheet S of A4 landscape size, which is the maximum width that can be passed, is passed.

  When the sheet S is discharged from the image forming apparatus in the arrow direction A, as shown in FIG. 3A, the first position is located below the contact portions 51 a to 51 c of the first detection lever 51. The leading end of the sheet comes into contact with the contact portions 52a and 53a of the second and third detection levers 52 and 53. Accordingly, the second and third detection levers 52 and 53 rotate in the direction of the arrow B, and accordingly, the second and third detection levers 52 and 53 press the first detection lever 51, and the first detection lever 51 Is also rotated in the direction of arrow C, resulting in the state shown in FIG.

  Here, when the second and third detection levers 52 and 53 are in contact with the contact portions 52 a and 53 a in this way, the width direction end of the sheet S is pushed down by the second and third detection levers 52 and 53. It is done. Therefore, before reaching the first detection lever 51, the sheet S is discharged while being deformed into a curved state in which the end in the width direction is lower than the center as shown in FIG.

  Since the sheet S is curved in the width direction in this manner, the stiffness in the conveyance direction of the sheet S becomes strong. After that, when the sheet S comes into contact with the first detection lever 51, the sheet S is a thin paper. Even in this case, the leading edge of the sheet hangs down and is stacked on the stacking tray 33 without being rounded. Thereafter, the sheet S is discharged to the stacking tray 33 by the discharge roller pair 32, and accordingly, the first to third detection levers 51 to 53 are moved to their original positions by their own weight or return means such as a spring (not shown). Return to.

  Next, as shown in FIG. 3C, when the sequentially discharged sheets S are fully loaded on the stacking tray 33, the detected portion 51d of the first detection lever 51 blocks the sensor 54 after the sheets are discharged. Thus, it is detected that the stacking tray 33 is full.

  Depending on the use environment and the like, the sheet may be discharged in a state where the rear end, which is the upstream end in the discharge direction, is largely curled upward. However, in this case, as shown in FIG. 3D, at least one of the second detection lever 52 and the third detection lever 53 is pressed by the rear end portion of the curled sheet S and rotates upward.

  Then, when the first detection lever 51 is rotated upward by the upward rotation of at least one of the second detection lever 52 and the third detection lever 53, it can be detected that the stacking tray 33 is full. . Thus, in the present embodiment, all of the first to third detection levers 51 to 53 function as members for detecting full load.

  FIG. 5 is a cross-sectional view showing a state when a small sheet having a small width, for example, an A5 size sheet S is passed vertically. Here, when the width is narrow, the sheet S does not contact the second detection lever 52 and the third detection lever 53. However, the narrow sheet S is stronger than the wide sheet having the same basis weight (thickness) and is relatively difficult to curl, so that the sheet S is neatly stacked on the stacking tray 33.

  Thus, according to the present embodiment, when a sheet is discharged, the sheet can be strengthened by bending the sheet so that both end portions are lower than the center portion in the width direction. In addition, when the second and third detection levers 52 and 53 are in contact with the sheet and rotated upward, the first detection lever 51 can be rotated upward. It is possible to discharge without reducing the loadability. In other words, when the sheet is discharged, the sheet is bent and when the second and third detection levers 52 and 53 are rotated upward, the first detection lever 51 is rotated upward to change the sheet according to the type of the sheet. A decrease in loadability can be prevented.

  Next, a second embodiment of the present invention will be described.

  FIG. 6 is a diagram illustrating a configuration of the sheet discharging apparatus according to the present embodiment. In FIG. 6, the same reference numerals as those in FIG. 2 described above indicate the same or corresponding parts.

  In FIG. 6, 62 is a second detection lever, and 63 is a third detection lever. In the present embodiment, these second and third detection levers 62 and 63 are each indicated by an arrow D along the rotation center axis 55. , Slidable (movable) in the E direction, that is, in the width direction. Accordingly, the user can move the second and third detection levers 62 and 63 to positions facing both side edges of the sheet S using a label (not shown) as a guide according to the size of the sheet S to be used.

  For example, when the sheet S used by the image forming apparatus is an A4 landscape sheet S, the second and third detection levers 62 and 63 are slid and moved to the position shown in FIG. When using a narrow A5 size sheet S, the second and third detection levers 62 and 63 are slid to the positions shown in FIG.

  And also by comprising in this way, the sheet | seat S can be curved irrespective of the size of the sheet | seat S used. Thereby, the stiffness in the conveying direction of the sheet S can be increased regardless of the size of the sheet S, and a more stable sheet discharging apparatus can be obtained.

  In the present embodiment, the second and third detection levers 62 and 63 are manually moved. However, the second and third detection levers 62 and 63 are moved using a motor. May be. In this case, for example, the size of the sheet S is detected by a size detection unit (not shown), and the motor is driven according to the detection result to move the second and third detection levers 62 and 63.

  Next, a third embodiment of the present invention will be described.

  FIG. 7 is a diagram illustrating a configuration of the sheet discharge device according to the present embodiment. In FIG. 7, the same reference numerals as those in FIG. 2 described above indicate the same or corresponding parts.

  In FIG. 7, reference numeral 64 denotes a first detection lever disposed at the center in the sheet width direction, and the first detection lever 64 is provided with a detected part 64d as detection means. Reference numerals 65 and 66 denote second and third detection levers that are positioned at the maximum width in which the sheet can be passed in the sheet width direction.

  67 is a fourth detection lever arranged between the first detection lever 64 and the second detection lever 65, and 68 is a fifth detection lever arranged between the first detection lever 64 and the third detection lever 66. is there. As described above, in the present embodiment, a plurality of sheet detection members for detecting the sheet S are provided. That is, in the present embodiment, two (a plurality of) second to fifth detection levers 65 to 68 that also function as side end pressing members are provided on both sides in the width direction of the first detection lever 64 that also functions as a center pressing member. ) Provided.

  Here, as shown in FIG. 8, the portion where the fourth detection lever 67 and the fifth detection lever 68 are in contact with the sheet S protrudes downward from the portion where the first detection lever 64 is in contact with the sheet. Further, the portion where the second detection lever 65 and the third detection lever 66 are in contact with the sheet S protrudes downward from the portion where the fourth detection lever 67 and the fifth detection lever 68 are in contact with the sheet. That is, in this embodiment, the detection lever protrudes downward from the center toward the end.

  The fourth and fifth detection levers 67 and 68 are located upstream of the first detection lever 64 in the discharge direction, and the second and third detection levers 65 and 66 are from the fourth and fifth detection levers 67 and 68. Is also located upstream in the discharge direction.

  In the present embodiment, the second and third detection levers 65 and 66 are provided, for example, at positions facing both side edges of the A4 landscape sheet S, and the fourth and fifth detection levers 67 and 68 are A5. It is provided at a position facing both end portions of the vertical sheet S.

  Thus, for example, when the A4 landscape sheet S is passed, the second and third detection levers 65 and 66 are pressed and rotated upward by the discharged sheet. When the second and third detection levers 65 and 66 are rotated upward in this manner, the fourth and fifth detection levers 67 and 68 are rotated upward by being pressed by the second and third detection levers 65 and 66. . Further, when the fourth and fifth detection levers 67 and 68 are pivoted upward in this manner, the first detection lever 64 is pushed up by being pushed by the fourth and fifth detection levers 67 and 68 and pivoted upward. To do.

  Note that when the sheet is discharged while the second and third detection levers 65 and 66 and the fourth and fifth detection levers 67 and 68 are rotated upward in this way, the end in the width direction of the sheet S is the second end. Are pushed down by fifth detection levers 65-68. As a result, the sheet S is discharged while being deformed into a curved state with its end portion lower than the central portion in the width direction.

  When the A5 vertical size sheet S is passed, the leading edge of the sheet S first comes into contact with the fourth and fifth detection levers 67 and 68. As a result, the end portion in the width direction of the sheet S is pushed down by the fourth and fifth detection levers 67 and 68, and the sheet S is discharged while being deformed into a curved state with the end portion lower than the center portion.

  Thus, in the present embodiment, the curvature as described in the first embodiment can be given to the sheet S regardless of the size of the used sheet S. Thereby, the stiffness in the conveying direction of the sheet S can be increased regardless of the size of the sheet S, and a more stable sheet discharging apparatus can be obtained.

1 is a diagram illustrating a schematic configuration of an electrophotographic color printer as an example of an image forming apparatus including a sheet discharging apparatus according to a first embodiment of the present invention. The perspective view which showed the structure of the said sheet | seat discharge apparatus. The figure explaining the sheet discharge operation | movement of the said sheet discharge apparatus. The perspective view explaining the state of the sheet | seat discharged | emitted by the said sheet | seat discharge apparatus. The figure explaining the state in the case of discharging the small sized sheet of the said sheet discharge apparatus. The perspective view which shows the structure of the sheet discharge apparatus concerning the 2nd Embodiment of this invention. The perspective view which shows the structure of the sheet discharge apparatus concerning the 3rd Embodiment of this invention. Sectional drawing which shows the structure of the said sheet | seat discharge apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Color printer 1B Image formation part 1D Sheet discharge apparatus 32 Discharge roller pair 33 Stack tray 50 Press part 51 First detection lever 51d Detected part 52 Second detection lever 53 Third detection lever 54 Light transmission type sensor 55 Center axis of rotation 62 second detection lever 63 third detection lever 64 first detection lever 64d detected portion 65 second detection lever 66 third detection lever 67 fourth detection lever 68 fifth detection lever S sheet

Claims (8)

In a sheet discharging apparatus comprising: a sheet discharging unit that discharges a sheet to a sheet stacking unit; and a pressing unit that presses the sheet discharged to the sheet stacking unit from above.
The pressing portion is
A central pressing member that is rotatable in the vertical direction and presses the central portion in the width direction orthogonal to the discharging direction of the sheet discharged by the sheet discharging means;
A side end pressing member that is rotatable in the up-down direction contacting the sheet discharged on both sides of the central pressing member,
When discharging a sheet, the sheet discharging apparatus is characterized in that both end portions of the discharged sheet are pressed by the side end pressing member on the upstream side in the discharging direction from the central pressing member.   2. The sheet discharge device according to claim 1, wherein when the side end pressing member is rotated upward in contact with the sheet, the central pressing member is rotated upward in conjunction with the sheet.   The sheet discharging apparatus according to claim 1, wherein the side end pressing member and the center pressing member have a common rotation center.   The sheet discharging apparatus according to claim 1, wherein the side end pressing member is movable in the width direction.   5. The sheet discharge device according to claim 1, wherein a plurality of the side end pressing members are provided on both sides in the width direction of the central pressing member.   The side end pressing member presses the upstream end in the discharge direction of the sheets stacked on the sheet stacking unit, and when pressed upward by the stacked sheets, The sheet discharging apparatus according to claim 1, wherein the central pressing member is rotated upward.   7. The center pressing member according to claim 1, wherein the center pressing member rotates upward in accordance with a sheet stacking amount, and detects the sheet stacking amount based on a rotation position of the center pressing member. The sheet discharging apparatus as described.   An image forming apparatus comprising: an image forming unit; and the sheet discharging apparatus according to claim 1 that discharges a sheet on which an image is formed by the image forming unit.

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