JP2006089201A - Sheet stacking device and image forming device with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet stacking device of simple structure capable of obtaining excellent stacking performance in relation to sheets of size in a wide range and applicable to a device having a plurality of sheet stacking parts. <P>SOLUTION: A free end of one of sheet presser arms 11 and 21 is arranged at a position where the minimum distance between a point, in which the free end is brought in contact with ejection trays 131 and 130, and an ejection point is longer than length of the sheet of one size in the carrying direction, and in the condition wherein a rear end of the sheet of a first size passes through the ejection part and carrying force is not applied to the sheet, a tip of the sheet collides with the arm 21 and moving speed in the ejecting direction is reduced by reaction force from the arm 21. Alternatively, the sheet is fallen, moving in the opposite direction, and in the condition wherein a tip of a sheet of a second size larger than the first size collides with the arm 21, while receiving the sheet carrying force from the ejection part, and passes through under the free end. After the rear end of the sheet passed through the ejection part, the minimum distance from the ejection part to a position, in which the arm 21 collides with the tip of the sheet, and angle formed by the sheet and the arm 21 at the collision position are selected for arrangement. The sheet stacking device of this structure is used. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a sheet accumulating apparatus with a full notice and full detection function and an image forming apparatus provided with the same.

In a sheet depositing apparatus that deposits sheets output from an image forming apparatus or the like, it is required to orderly deposit sheets at predetermined positions while maintaining the order of discharged sheets, that is, good stacking properties. For this reason, a technique is known in which a sheet pressing arm that prevents the discharged sheet from jumping upstream in the discharge direction is disposed on the sheet receiving base (for example, see Patent Document 1).
If the sheet size is one type, the shape and position of the sheet pressing arm may be optimized according to the size. However, in a sheet stacking apparatus that handles sheets of a plurality of sizes, the sheets of the plurality of sizes are used. Therefore, it is necessary to determine the shape and position of the sheet pressing arm so as to obtain a good stacking property. However, in reality, it is difficult to obtain uniformly good stacking properties for all size sheets. For example, in order to hold the sheet having the shortest sheet length L1 among the corresponding sizes, the free end of the arm must be disposed so as to hold the sheet within a distance of L1 from the sheet discharge roller. In this case, the sheet having the longest sheet length L2 among the corresponding sizes is pressed by the free end of the arm at a distance within L1 from the sheet discharge roller, and in this state, the sheet is longer than the length of L2-L1. When the leading edge of the sheet is advanced, the trailing edge of the sheet is separated from the paper discharge roller, and the advance is stopped. Therefore, as the difference between L1 and L2 is larger, that is, as the apparatus handles a wide range of sheets, the sheet deposition conditions differ depending on the size, and it is difficult to obtain a uniform action by the sheet pressing arm. At this time, if the “strain” of the large-sized sheet is insufficient or the force of the arm that holds the sheet is too strong, the sheet is wrinkled or the smooth discharge of the sheet is hindered, and the leading edge advances in the middle. Sometimes it stopped. As a technique for avoiding such a problem, for example, a technique of providing a movable alignment member called a jogger on a tray is known. This is a technique for aligning the sheet by pressing the end of the discharged sheet with a jogger. Alternatively, a jogger and a sheet pressing arm are used in combination, and the sheet pressing arm is acted on only a large size sheet for which it is difficult to obtain particularly good stacking properties. Alternatively, as another sheet aligning method, the sheet is inclined in one direction and a position restricting member is provided at the lower part of the inclination, and the sheet deposited on the inclined tray is moved to the lower inclined part by the action of gravity, and the position restricting member is used. There are known techniques for making them consistent.
JP-A 64-8180

  In the prior art, the sheet size that provides good stacking properties by the sheet pressing arm is limited to a narrow range. On the other hand, in the method using a jogger, it is necessary to provide a complicated alignment mechanism, and the user may touch the moving alignment member. Therefore, it is preferable to have as few movable parts as possible in terms of safety. In addition, the method of inclining the sheet in one direction has a simple structure, but a large-sized sheet has a large contact area between the upper and lower sheets in a stacked state, so the frictional force received by the sheet is large. In order to overcome and align the sheets, the inclination of the tray must be increased. However, in order to ensure a large inclination, extra space is required above and below the tray, which is not suitable for a small sheet stacking apparatus.

  In recent years, with the downsizing of the apparatus, there are an increasing number of multifunction machines in which the outer shape of the apparatus is formed in a “U” shape and the discharged sheets are deposited in the central space. In such a multi-function machine, a sheet stacking apparatus that can obtain a sufficient number of stacked sheets and good stacking properties for sheets discharged to a limited size area is particularly desired. In many cases, a “movable job separator” or the like is provided as a sheet stacking device for branching a sheet discharge destination according to a plurality of print processing modes such as a printer, a copier, and a fax machine.

  The present invention can also be applied to an apparatus having a plurality of sheet stacking portions in which a sheet pressing arm and a discharge tray are arranged so as to obtain a good stacking property for a wide range of sheets with a simple structure. A sheet deposition apparatus is provided.

  The present invention relates to a discharge unit that conveys and discharges a sheet, a sheet accumulation unit that deposits a sheet so that the upstream side in the discharge direction of the discharged sheet is lower than the downstream side, and the upstream side of the sheet accumulation unit A sheet discharge tray having a sheet restricting portion disposed at the end of the sheet, a support end supported at one end by an arm support member, and a sheet discharge tray or a sheet discharge tray downstream of the support end in the sheet discharge direction. A sheet pressing arm having a free end that contacts the sheet deposited on the sheet directly or via a contact member, and the arm has a free end of the arm or a contact member attached to the free end in contact with the sheet discharge tray. The free end is disposed at a position where the shortest distance between the point and the discharge unit is longer than the length in the conveyance direction of the first size sheet, and the rear end of the first size sheet passes through the discharge unit. The sheet tip collides with the arm without receiving the conveying force to the sheet, and the repulsive force from the arm reduces the moving speed in the discharging direction or falls while moving in the opposite direction, and the first size larger than the first size. With the two-size sheet receiving the sheet conveying force from the discharge unit, the leading edge of the sheet collides with the arm and passes under the free end, and after the sheet trailing edge passes through the discharge unit, The shortest distance from the discharge unit to the position where the arm collides with the sheet leading end and the angle formed by the sheet and the arm at the collision position are selected and arranged so as to stop the movement, and the discharge tray is placed on the discharge tray. The fallen first size sheet is deposited with an inclination to the upstream side of the free end of the arm, and the second size sheet whose tip has passed under the free end of the arm is deposited in a state of being pressed by the free end of the arm. And position an inclined shape with respect to sea urchin arm to provide a sheet deposition device which is arranged to be selected.

  According to the sheet stacking apparatus of the present invention, the shortest distance between the point where the free end of the arm or the contact member attached to the free end contacts the sheet discharge tray and the discharge unit is longer than the length of the first size sheet in the conveyance direction. The free end is arranged at a long position, the leading end of the sheet collides with the arm and the repulsive force from the arm with the trailing end of the first size sheet passing through the discharge portion and not receiving the conveying force to the sheet. The leading edge of the sheet collides with the arm in a state where the second size sheet, which is larger than the first size, receives the sheet conveying force from the discharge unit, while decreasing the moving speed in the discharging direction or moving in the opposite direction. Pass through the free end, and after the sheet trailing edge passes through the discharge section, the shortest distance from the discharge section to the position where the arm collides with the sheet front end and the collision position so as to stop the movement of the sheet in the discharge direction. Sheet An angle formed by the arm is selected and arranged, and the sheet discharge tray is configured such that the first size sheet dropped on the sheet discharge tray is accumulated on the upstream side of the arm free end, and the leading end is the arm free end. Since the position of the arm and the shape of the slope are selected and arranged so that the second size sheet that passes under the sheet is deposited while being pressed against the free end of the arm, the first and Good stacking properties can be obtained for a wide range of sheets including a larger second size.

  A sheet stacking apparatus according to the present invention includes a discharge unit that conveys and discharges a sheet, a sheet stacking unit that deposits a sheet by tilting the discharged sheet so that the upstream side in the discharge direction is lower than the downstream side. A sheet discharge tray having a sheet regulating portion disposed at an upstream end of the sheet discharge section, a support end supported at one end by an arm support member, and a sheet discharge tray on the downstream side in the sheet discharge direction from the support end. Alternatively, a sheet pressing arm having a free end that comes into contact directly or via a contact member with the sheets stacked on the paper discharge tray, and the arm is free of a contact member attached to the free end or the free end of the arm. The free end is arranged at a position where the shortest distance between the point in contact with the paper tray and the discharge unit is longer than the length in the conveying direction of the first size sheet, and the rear end of the first size sheet The leading edge of the sheet collides with the arm without passing through the discharge part and receives the conveying force to the sheet, and the repulsive force from the arm reduces the moving speed in the discharging direction or falls while moving in the opposite direction. After a sheet having a second size larger than the first size receives a sheet conveying force from the discharge unit, the leading end of the sheet collides with the arm and passes under the free end, and the trailing end of the sheet passes through the discharge unit. The shortest distance from the discharge unit to the position where the arm collides with the sheet leading end and the angle formed by the sheet and the arm at the collision position are selected and arranged so as to stop the movement of the sheet in the discharge direction, The first size sheet that has fallen on the paper discharge tray is inclined and accumulated upstream from the free end of the arm, and the second size sheet whose tip passes under the free end of the arm is pressed by the free end of the arm. The The shape of the position and the inclination with respect to the arm is arranged to be selected to be deposited in state.

Here, the contact member is a member that comes into contact with the sheet to such an extent that the sheet does not interfere with the progress of the sheet when it receives the conveyance force from the paper discharge roller. It may be. Further, the sheet restricting portion refers to a member arranged such that a sheet that is inclined and deposited on the sheet discharge tray slides toward a lower inclined side and one end thereof is in contact with the restricting member and aligned. However, the present invention is not limited to this, and for example, a plurality of columnar members may be used.
In this specification, the size of the sheet means the size of the sheet in the discharge direction, and the size in the direction orthogonal to the discharge direction is not limited.

The arm is configured to receive a repulsive force from the arm by the action of its own weight, flexibility or both when the tip of the discharged sheet collides with the arm,
After the leading edge of the sheet collides with the arm in a state where the first size sheet does not receive the conveying force from the discharging section, the sheet falls while decreasing the moving speed in the discharging direction or moving in the opposite direction. The traveling direction of the leading edge of the sheet that collides with the arm moves toward the arm so that the leading edge of the sheet descends and passes under the free end of the arm after the leading edge of the sheet collides with the arm while the sheet receives the conveying force from the discharge unit. The angle to be made and the weight of the arm, the flexibility, or both may be selected.
In this way, it is good for a wide range of sheets by appropriately setting the angle formed by the traveling direction of the leading edge of the sheet colliding with the arm and the weight of the arm, the flexibility of the arm, or both. Can be secured.

In addition, the position of the arm support portion relative to the discharge portion can be selected so that the arm support portion can set the shortest distance from the discharge portion to the position where the sheet collides with the arm according to the length of the first size sheet. May be configured.
In this way, since the length of the first size sheet can be made to correspond to the optimum size according to the use situation, the position of the arm support end is selected according to the sheet of the size frequently used by the user, Good stacking property can be secured for the sheet of the size.

Furthermore, the sheet stacking portion of the sheet discharge tray is inclined such that when a sheet having a size equal to or smaller than the first size falls on the sheet discharge tray, the sheet is stacked with the trailing edge approaching the regulating member side by the weight of the sheet. May have a part.
If it does in this way, about the sheet | seat of the 1st size or less size, favorable stacking property can be ensured by the effect | action of the inclination part of a discharge tray and a control member.

The arm is arranged so that the arm collides with the central part of the side on the leading end side of the discharged sheet, or so as to collide with two points that are equidistant from the central part of the side on the leading end side. It may be arranged.
In this way, when the sheet collides with the arm, a repulsive force symmetrical to the left and right is received from the arm about the axis extending in the discharge direction through the center of the side on the leading end side, so that the sheet is orthogonal to the discharge direction. The moment for shifting the sheet does not act on the sheet, and therefore, good stacking properties can be ensured in the direction orthogonal to the sheet discharge direction.
An image forming apparatus according to the present invention includes any one of the sheet deposition apparatuses. Therefore, in the image forming apparatus of the present invention, good stacking properties of the sheets discharged from the apparatus are realized over a wide range of sizes.

The present invention will be described in detail below based on the embodiments shown in the drawings.
(Embodiment 1)
In this embodiment, an overall structure of an embodiment of a sheet deposition apparatus according to the present invention and an embodiment of an image forming apparatus provided with the same will be described below.
FIG. 4 is an explanatory diagram showing a configuration example of the image forming apparatus of this embodiment. As shown in FIG. 4, the image forming apparatus of this embodiment is roughly composed of a scanner unit, a printing unit, and a sheet conveying unit which is another part.

  The scanner unit irradiates light on a document and generates image data corresponding to the image of the document from the reflected light. The printing unit forms a visible image based on the image data generated by the scanner unit, and prints the visible image on a predetermined transfer sheet (sheet). The sheet conveying unit supplies the sheet to the printing unit and discharges the printed sheet. Further, the sheet conveying unit includes a roller driving mechanism which is a characteristic configuration of the image forming apparatus. This configuration will be described later.

  Next, the configuration of each part of the image forming apparatus will be described. First, the scanner unit will be described. The scanner unit has a document table 101 made of transparent glass on the upper surface. A scanner optical system is disposed below the document table 101. The scanner optical system includes an exposure light source 102, a reflecting mirror 103, an imaging lens 104, and a photoelectric conversion element (CCD) 105. The exposure light source 102 is a light source 102 for irradiating light on a document placed on the document table 101. The reflecting mirror 103 guides the reflected light from the document to the imaging lens 104 and the CCD 105 as indicated by a straight line in the drawing, for example. The CCD 105 receives reflected light imaged by the imaging lens 104 and generates an electrical signal corresponding to the reflected light as an image signal.

  Next, the printing unit and the sheet conveying unit will be described. The printing unit includes a photosensitive roller 111, a charging unit 112, a developing unit 113, a transfer charger 114, a fixing roller 115, a cleaning device 116, a laser scanning unit (LSU) 117 (not shown), and a fixing paper detection switch. The photosensitive roller 111 is a drum-shaped photosensitive roller 111, and is driven to rotate so that a sheet conveyed through a main conveyance path 121, which will be described later, is in contact with the surface of the photosensitive roller 111 at the same speed. The charging unit 112 charges the surface of the photosensitive roller 111 to a predetermined potential. The LSU 117 scans the surface of the charged photosensitive roller 111 by scanning a laser beam in a direction parallel to the rotation axis of the photosensitive roller 111, thereby reading the surface of the photosensitive roller 111 from the scanner unit. An electrostatic latent image corresponding to the image signal of the original is formed. The developing unit 113 develops the electrostatic latent image formed on the surface of the photosensitive roller 111 using the LSU 117 with the developing roller 118, and forms a toner image (a visible image) on the surface of the photosensitive roller 111. . The transfer charger 114 transfers the toner image on the photosensitive roller 111 to a sheet. The fixing roller 115 heat-fixes the unfixed toner image transferred to the printed sheet on the sheet. The fixing paper detection switch detects that the sheet has passed the fixing roller 115. The cleaning device 116 removes the toner remaining on the surface of the photosensitive roller 111 after the toner image is transferred to the sheet.

The sheet conveyance unit includes a main conveyance path 121, a sub conveyance path 122, a fixed sheet feeding cassette 123, a pickup roller 124, a registration roller 125, a guide member 126, a sheet discharge port 127, a sheet discharge roller 128, and a conveyance roller 129. A pre-registration detection switch is provided. The fixed paper feed cassette 123 is for storing sheets for printing.
The pick-up roller 124 is a half-moon-shaped roller for outputting sheets one by one from the fixed sheet feeding cassette 123. The pre-registration detection switch is for detecting that the sheet conveyed by the pickup roller 124 has passed a predetermined position on the main conveyance path 121 and outputting a predetermined detection signal. The registration roller 125 temporarily holds the sheet conveyed through the main conveyance path 121. The sheet has a function of transporting the sheet with good timing in accordance with the rotation of the photosensitive roller 111 so that the leading edge of the toner image on the photosensitive roller 111 can be transferred in synchronization with the leading edge of the sheet. That is, the registration roller 125 conveys the sheet based on the detection signal output by the pre-registration detection switch so that the leading edge of the toner image on the photosensitive roller 111 is synchronized with the leading edge of the printing range on the sheet.

  The paper discharge roller 128 is provided in the vicinity of the paper discharge port 127 and allows the sheet discharged from the fixing roller 115 to be fed into the first paper discharge tray 130 or the second paper discharge tray 131 (fixed paper feed below the scanner unit). It is a roller for discharging to a movable tray disposed on the upper portion of the cassette 123. The paper discharge roller 128 has a function as a back surface printing mechanism together with the guide member 126 and the sub transport path 122. That is, in normal single-sided printing, the guide member 126 is arranged in the direction B in FIG. 4 so that the sheet can be conveyed from the main conveyance path 121 to the paper discharge roller 128. On the other hand, when printing on both sides of the sheet, when printing on the first side of the sheet is completed and the trailing edge of the sheet is discharged from the main conveyance path 121, the guide member 126 is rotated in the A direction to discharge the sheet. The sheet reversely fed from the roller 128 is disposed so as to be guided to the sub conveyance path 122. The paper discharge roller 128 rotates in the forward direction (the direction in which the sheet is output from the paper discharge port 127) until the trailing edge of the sheet output from the fixing roller 115 passes through the guide member 126, and then in the reverse direction. Rotate. Thus, the sheet passes through the guide member 126 and is conveyed to the sub-conveying path 122, and is conveyed again to the registration roller 125 by the conveying roller 129, and printing is performed on the second surface (back surface).

  The first paper discharge tray 130 is provided with a particularly large inclined portion on the upstream side with respect to the discharge direction with respect to the portion in contact with the roller attached to the free end of the sheet pressing arm 21. The second discharge tray 131 is also provided with a particularly large inclined portion on the upstream side with respect to the discharge direction with respect to the portion where the roller attached to the free end of the sheet pressing arm 11 contacts. As will be described later, these inclined portions act to ensure stackability of sheets of the first size and smaller sizes. However, for the first size and larger seats, the stacking performance is improved by the action of the sheet pressing arms 11 and 21, so the downstream side of the portion where the roller attached to the arm free end is in contact, There is no need to provide a large slope.

(Embodiment 2)
In this embodiment, a description will be given of a first embodiment in which good stacking properties of the stacked sheets are ensured by the action of the sheet pressing arm and the sheet discharge tray.
FIG. 1 is an explanatory diagram showing a state in which discharged first-size sheets are stacked in a sheet stacking apparatus having a sheet pressing arm according to the present invention. FIG. 1 shows a case where discharged sheets are stacked on the first discharge tray 130. On the first paper discharge tray, a “<”-shaped sheet pressing arm 21 having a bent portion is arranged. One end of the arm 21 is fixed to an arm support portion 22 disposed below the second paper discharge tray 131, and the other end is in contact with the first paper discharge tray 130 via a roller. The arm 21 has flexibility, and the roller at the free end is pressed against the first paper discharge tray 130 by its elasticity.

  The operation of the arm 21 and the first paper discharge tray 130 for the first size sheet is as follows. The sheet S1 conveyed at the front end through the paper discharge roller 128 has its traveling direction substantially horizontal due to the conveyance force received from the paper discharge roller 128 and the “strain” of the sheet even after the front end passes through the paper discharge roller. It moves in the direction of arrow C while keeping it. Eventually, the trailing edge of the sheet S1 moves away from the paper discharge roller 128 and jumps out in a substantially horizontal direction with the conveyance speed of the paper discharge roller as the initial speed, and then the front end collides with the sheet pressing arm 21. Since the arm 21 has elasticity, the sheet S1 receives a repulsive force in the direction of arrow D from the arm 21 due to its elasticity, and reduces the horizontal speed or in the opposite direction, as shown in FIG. Receive the power of As a result, the sheet S1 loses its speed in the discharge direction, and naturally falls onto the first discharge tray 130 as shown in FIG. Since the first discharge tray is inclined, the sheet S1 slides to the upstream side indicated by the arrow E by the action of its own weight, and one end of the first discharge tray 130 as shown in FIG. The sheet restricting portion 35 is stopped. Next, the discharged sheet S2 is deposited on the sheet S1 through a similar process so that one end of the discharged sheet S2 hits the sheet regulating portion 35 of the first discharge tray 130. In this manner, the first size sheets are neatly stacked on the first paper discharge tray 130.

  As described above, the arm 21 is disposed at a position where the leading edge of the sheet collides with the trailing edge of the first size sheet leaving the discharge roller 128 and protruding in a substantially horizontal state, and the leading edge of the sheet is the arm. The angle between the traveling direction of the sheet before the collision and the arm 21 of the collision part so as to drop while returning to the opposite direction by reducing the speed in the discharging direction due to the collision with 21, that is, the mounting angle of the arm 21 to the support member and the arm By setting the bending angle of 21, it is possible to ensure good stacking properties for the first size sheet.

The length of the first size sheet is L3, the trailing edge of the sheet leaves the discharge roller 128, d is the distance to move through the space while maintaining the horizontal speed with the conveying speed as the initial speed, and the sheet pressing arm so as to collide with the sheet , Where X is the position where X should be placed,
L3 <X ≦ L3 + d
The relationship holds.

  FIG. 5 shows a case where the discharged first-size sheet S7 is accumulated on the second discharge tray 131. Also in this case, the arm 11 is arranged at a position where the leading edge of the sheet collides with the trailing edge of the first size sheet leaving the discharge roller 128 and protruding in a substantially horizontal state, and the leading edge of the sheet is the arm 11. The angle between the traveling direction of the sheet before the collision and the arm 11 of the collision part so as to fall while reducing the speed in the discharge direction or returning to the opposite direction due to the collision with the arm 11, that is, the mounting angle of the arm 11 to the support member and the arm 11 By setting the bend angle, a good stacking property for the first size sheets deposited on the second paper discharge tray 131 can be secured.

(Embodiment 3)
In this embodiment, a second embodiment will be described in which the stacking property of the stacked sheets is ensured by the action of the sheet pressing arm and the sheet discharge tray.
FIG. 2 is an explanatory diagram showing a state in which a sheet S3 having a second size larger than the first size is discharged and deposited in the sheet stacking apparatus according to the present invention. The operation of the arm 21 and the first paper discharge tray 130 for the second size sheet is as follows.

  The sheet S3 conveyed at the front end through the paper discharge roller 128 has its traveling direction substantially horizontal due to the conveyance force received from the paper discharge roller 128 and the "strain" of the sheet even after the front end passes through the paper discharge roller. It moves in the direction of arrow F while keeping it. In the case of the sheet S3, as shown in FIG. 2A, the leading end collides with the sheet pressing arm 21 before the rear end is separated from the sheet discharge roller 128, and thus has a conveying force in the sheet discharge direction. The elastic force of the arm 21 causes a repulsive force downstream and downward in the sheet discharge direction as indicated by an arrow G. As a result, the leading end of the sheet S3 descends along the arm 21, then hits the first paper discharge tray 130, and passes under the free end of the arm 21 along the first paper discharge tray 130. Until the trailing edge of the sheet S3 leaves the paper discharge roller 128, the leading edge of the sheet S3 is moved along the first paper discharge tray 130 by the conveying force from the paper discharge roller 128 and the "straining" of the sheet S3. As shown in FIG. When the trailing edge of the sheet S3 moves away from the paper discharge roller 128, the sheet S3 loses the conveyance force from the paper discharge roller 128. At this time, since the sheet S3 is pressed by a roller attached to the free end of the arm 21, braking is applied by the frictional force with the first paper discharge tray 130, and the progress in the sheet discharge direction is stopped. (FIG. 2 (c)). The sheet portion on the upstream side of the roller attached to the free end of the arm 21 naturally falls on the first paper discharge tray 130 as indicated by an arrow H in FIG. The sheet S4 that is subsequently discharged is also deposited on the sheet S3 of the first discharge tray 130 through a similar process. In this way, the second size sheets are stacked on the first paper discharge tray 130 in an orderly manner.

  As described above, the arm 21 is disposed at a position where the leading edge of the sheet collides before the trailing edge of the second size sheet leaves the paper discharge roller 128, and the leading edge of the sheet collides with the arm 21 due to the collision with the arm 21. The angle between the traveling direction of the sheet before the collision and the arm 21 of the collision part, that is, the angle at which the arm 21 is attached to the support member and the bending angle of the arm 21 so that the sheet travels downward and passes below the free end. And the arm 21 against the paper discharge roller 128 is not hindered when the sheet travels below the free end, and is braked after the rear end of the sheet leaves the paper discharge roller 128. By selecting the positions of the free end and the support end and the arrangement of the first discharge tray 130 with respect to the discharge roller 128, good stacking performance can be ensured even for the second size sheet. It can be.

  FIG. 6 shows a case where the discharged second-size sheet S9 is deposited on the second discharge tray 131. Also in this case, the arm 11 is disposed at a position where the leading edge of the sheet collides before the trailing edge of the second size sheet leaves the paper discharge roller 128, and further, the leading edge of the sheet follows the arm by the collision with the arm 11. Then, the angle between the traveling direction of the sheet before the collision and the arm 11 of the collision part, that is, the angle at which the arm 11 is attached to the support member and the bending angle of the arm 11 so that the sheet travels downward and passes under the free end. In addition, the free movement of the arm 11 with respect to the discharge roller 128 so that the sheet does not obstruct the progress of the sheet when the sheet advances below the free end and the brake is applied after the rear end of the sheet leaves the discharge roller 128. By selecting the position of the end and the support end and the position of the second discharge tray 131 with respect to the discharge roller 128, the second size sheets stacked on the second discharge tray 131 are selected. Even good stacking resistance can be ensured.

(Embodiment 4)
In this embodiment, a third embodiment for securing a good stacking property of the accumulated sheets by the action of the paper discharge tray will be described.
FIG. 3 is an explanatory diagram showing a state in which the sheet S5 having a third size smaller than the first size is discharged and deposited in the sheet stacking apparatus of the present invention.

  The operation of the first paper discharge tray 130 for the third size sheet is as follows. The sheet S5 conveyed at the front end through the paper discharge roller 128 has its traveling direction substantially horizontal due to the conveyance force received from the paper discharge roller 128 and the "strain" of the sheet even after the front end passes through the paper discharge roller. It moves in the direction of arrow J in FIG. Eventually, the trailing edge of the sheet S5 moves away from the paper discharge roller 128, and jumps out in a substantially horizontal direction with the conveyance speed of the paper discharge roller as the initial speed. Since the sheet is smaller than the first size, the leading end advances in the direction of arrow K in FIG. 3B without colliding with the sheet pressing arm 21 and naturally falls on the first paper discharge tray. Since the first discharge tray is inclined, the sheet S5 slides to the upstream side in the discharge direction indicated by the arrow L due to its own weight (see FIG. 3C), and the first discharge tray 130 It strikes against the sheet restricting portion 35 at one end (see FIG. 3D). Next, the discharged sheet S6 is deposited on the sheet S5 through the same process so that one end of the discharged sheet S6 hits the sheet regulating portion 35 of the first discharge tray 130. In this way, the third size sheets are stacked on the first paper discharge tray 130 in an orderly manner.

As described above, with respect to the first paper discharge tray 130, the roller attached to the free end of the arm 21 is inclined on the upstream side of the portion in contact with the first paper discharge tray 130. Also good stacking properties can be secured.
FIG. 7 shows a case where the discharged third-size sheet S10 is deposited on the second discharge tray 131. In this case as well, the second paper discharge tray 131 is good for the third size sheet by providing the roller attached to the free end of the arm 11 to the upstream side of the portion in contact with the second paper discharge tray 131. Can be secured.

(Embodiment 5)
As described in the second embodiment, the sheet pressing arm may be disposed at a position where the leading edge of the sheet collides with the trailing edge of the first size sheet leaving the discharge roller 128 and protruding in a substantially horizontal state. . It is convenient if the first size can be selected in accordance with the area where the sheet stacking apparatus is used and the usage situation of the user.

  For example, in regions such as the United States where inch-size sheets are used, the first size corresponds to letter horizontal feed, and in regions such as Europe where AB-size sheets are used, the first size is A4 horizontal feed. The case of making it correspond to will be described. In the letter lateral feed, the sheet length in the discharge direction is about 216 mm. On the other hand, in A4 horizontal feed, the sheet length in the discharge direction is 210 mm. Therefore, in the area using the inch system, if the distance from the paper discharge roller to the arm support portion is increased by 6 mm corresponding to the difference in sheet length compared to the area using the AB system, the letter size in the inch system area is obtained. The repulsive force that the sheet receives from the arm and the repulsive force that the A4 size sheet receives from the arm in the AB region can be made substantially equal.

  In Japan, there are users who mainly use A4 size sheets and users who mainly use B5 size sheets. In such a case, the first size may correspond to the size mainly used by the user. In the B5 size, the sheet length in the discharge direction is 182 mm, which is 28 mm shorter than the A4 size. Therefore, for a user who mainly uses the B5 size, the distance from the paper discharge roller to the arm support portion may be shorter by 28 mm than a user who mainly uses the A4 size. In this way, a good stacking property can be obtained for the B5 size sheet by the action of the sheet, the pressing arm and the paper discharge tray as described in the second embodiment. At this time, the A4 size is included in the second size larger than the first size. Therefore, a good stacking property can be obtained for the A4 size sheet by the action described in the third embodiment.

  FIG. 9 is an explanatory diagram showing an aspect of an arm support portion that can select a position from the paper discharge roller in accordance with the sheet size. FIG. 9A is a cross-sectional view showing a detailed cross-sectional shape of each of the members 41 a to 41 e and 42 constituting the arm support portion and a cross-sectional shape of a portion supported by the arm support portion of the sheet pressing arm 11. And FIG.9 (b) has shown the state which combined each member.

The members 41a to 41e all have the same shape, and have screw holes 43, 44, and 45 that penetrate each member in the horizontal direction. In the assembled state of the arm support portion, the screws 61 are screwed so as to pass through all the screw holes 43 of the members 41a to 41e, reach the tip of the screw holes 46 of the member 42, and fix the members integrally. To do. The arm 11 is fixed so as to be sandwiched between any two adjacent members among the members 41 a to 41 e or 42. With the fixing screws, the respective members are integrally fixed so as to penetrate the screw hole 44 and the screw hole 50 of the arm 11 and the tip reaches the screw hole 47. Further, the other fixing screws are used to integrally fix the respective members so that the distal end reaches the screw hole 48 through the screw hole 45 and the screw hole 51 of the arm 11.
As described above, the integrally fixed arm and the arm support member are, for example, a screw 62 attached to an attachment member disposed below the scanner unit of the image forming apparatus illustrated in FIG. 4 or below the second paper discharge tray 131. By being screwed from below, it is fixed.

  FIG. 10 is an explanatory view showing a different embodiment of the arm support portion that allows the position from the paper discharge roller to be selected according to the sheet size. The rail 63 shown in FIG. 10 has a shape in which the cross section perpendicular to the sliding direction has an opening at the center of the lower side of the rectangle as shown in FIG. The moving member 64 moves, and the arm support members 41 and 42 and the arm 11 attached integrally with the sliding member move along the guide rail 63 in the direction of the arrow Q shown in FIG. The support end of the arm 11 can be moved to an arbitrary position of the guide rail, but is held at a predetermined position by the frictional force between the guide rail 63 and the sliding member 64.

By using a mechanism as shown in FIG. 9 or FIG. 10, the arm can be arranged at an optimum position according to the size of the sheet. The user may select the arm position, but is not limited thereto. It may be arranged at a position corresponding to the destination at the time of factory shipment, or a service engineer may decide the arrangement of the arm according to the installation environment of the machine.
FIG. 8 is an explanatory diagram showing a state when the arm 21 is arranged at an optimum position for each of the A4 size sheet and the B5 size sheet. 8A shows the optimal arm position for the A4 size sheet and FIG. 8B shows the B5 size sheet.

In FIG. 8A, when the shortest distance between the point R1 where the A4 size sheet collides with the arm 21 and the paper discharge roller 128 is Lr1,
210 (mm) <Lr1 (mm) ≦ 210 + d (mm)
The relationship is established. Here, d is the distance that the trailing edge of the sheet leaves the paper discharge roller 128 and moves through the space while maintaining a substantially horizontal state with the conveyance speed as the initial speed.
On the other hand, in FIG. 8B, when the shortest distance between the point R2 where the B5 size sheet collides with the arm 21 and the paper discharge roller 128 is Lr2,
182 (mm) <Lr1 (mm) ≦ 182 + d (mm)
The relationship is established.

(Embodiment 6)
FIG. 11 is an explanatory diagram showing an example of the arrangement of sheets and sheet pressing arms when the second paper discharge tray 131 is viewed from above. As shown in FIG. 11, sheets of different sizes are discharged so that the centers of the sides of the sheet orthogonal to the discharge direction are aligned on the same straight line P along the discharge direction. The sheet pressing arm 11 is arranged so that the straight line P and the center of the arm are aligned. The rollers attached to the free end of the arm 11 are arranged at the same distance from the arm on both sides of the arm. As a result, the force with which the roller presses the sheet is balanced about the straight line P, and the traveling direction of the sheet is kept parallel to the straight line P.

  FIG. 11 shows the case where the number of arms 11 is one. However, when a plurality of arms are arranged, in the case of an even number, each pair of arms is arranged at a target position with respect to the straight line P, and The force that holds the sheet is balanced about the straight line P, and the traveling direction of the sheet is kept parallel to the straight line P. In the case of an odd number, one of them is arranged so that the straight line P and the center of the arm are aligned, as shown in FIG. What is necessary is just to arrange | position to the object position.

Further, by arranging the arm as described above, it is expected that the repulsive force received when the leading end portion of the sheet larger than the first size collides with the arm is also targeted with the straight line P as the axis.
By arranging the arm as described above, a repulsive force is received from the arm which is symmetrical with respect to the central point where the edge of the sheet intersects the straight line P, so the sheet is shifted in the direction perpendicular to the sheet discharge direction. Therefore, good stacking properties can be ensured in the direction orthogonal to the sheet discharge direction.

It is explanatory drawing which shows a mode that the sheet | seat of the 1st size discharged | emitted in the sheet | seat deposition apparatus of this invention is accumulated. (Embodiment 2) It is explanatory drawing which shows a mode that the sheet | seat S3 of 2nd size larger than 1st size is discharged | emitted and deposited in the sheet | seat deposition apparatus of this invention. (Embodiment 3) It is explanatory drawing which shows a mode that the sheet | seat S5 of 3rd size smaller than 1st size is discharged | emitted and deposited in the sheet | seat deposition apparatus of this invention. (Embodiment 4) It is explanatory drawing which shows the structural example of the image forming apparatus which concerns on the sheet | seat deposition apparatus of this invention. (Embodiment 1) FIG. 6 is an explanatory diagram illustrating a state where discharged first-size sheets S7 are stacked on a second discharge tray in the embodiment of the present invention. (Embodiment 2) FIG. 10 is an explanatory diagram showing a state where discharged second-size sheets S9 are deposited on a second discharge tray in the embodiment of the present invention. (Embodiment 3) In the embodiment of the present invention, the discharged third-size sheet S10 is an explanatory diagram showing a state of being deposited on a second discharge tray. (Embodiment 4) In one Embodiment of this invention, it is explanatory drawing which shows a mode when the arm 21 is each arrange | positioned in the optimal position with respect to the sheet | seat of A4 size and B5 size. (Embodiment 5) In the sheet stacking apparatus of the present invention, it is an explanatory view showing an aspect of an arm support portion that can select a position from a sheet discharge roller according to the sheet size. (Embodiment 5) In the sheet stacking apparatus of the present invention, it is an explanatory view showing a different embodiment of the arm support portion that allows the position from the sheet discharge roller to be selected according to the sheet size. (Embodiment 5) In the sheet stacking apparatus of this invention, it is explanatory drawing which shows an example of arrangement | positioning of a sheet | seat and a sheet | seat presser arm when a 2nd paper discharge tray is seen from upper direction. (Embodiment 6)

Explanation of symbols

11, 21 Seat holding arms 12, 22 Arm support portions 13, 23 Deflection restricting portions 35, 36 Seat restricting portions 41, 41a to 41e, 42 Arm support portion constituting members 43 to 51 Screw holes 63 Guide rails 64 Slide members 70F, 70R frame 71 drive motor 101 document table 102 exposure light source 103 reflecting mirror 104 imaging lens 105 photoelectric conversion element, CCD
111 Photosensitive roller 112 Charging unit 113 Developing unit 114 Transfer charger 115 Fixing roller 116 Cleaning device 117 LSU
118 Developing roller 121 Main transport path 122 Sub transport path 123 Fixed paper feed cassette 124 Pickup roller 125 Registration roller 126 Guide member 127 Paper discharge port 128 Paper discharge roller 129 Carrying roller 130 First paper discharge tray 131 Second paper discharge tray

Claims (6)

A discharge unit that conveys and discharges the sheet;
A sheet discharge unit including a sheet stacking unit that deposits the sheet so that the upstream side in the discharge direction of the discharged sheet is lower than the downstream side, and a sheet regulating unit that is disposed at an upstream end of the sheet stacking unit. A tray,
A support end whose one end is supported by the arm support member, and a free end which is in contact with a sheet stacked on the sheet discharge tray or the sheet discharge tray directly or via a contact member at a downstream side of the support end in the sheet discharge direction. A sheet pressing arm having
The arm is located at a position where the shortest distance between the free end of the arm or the contact member attached to the free end and the discharge portion and the discharge portion is longer than the length of the first size sheet in the conveyance direction. The free end is arranged, and the leading end of the sheet collides with the arm in a state where the trailing end of the first size sheet passes through the discharging unit and does not receive the conveying force to the sheet, and the repulsive force from the arm moves in the discharging direction. Decreasing the moving speed or moving it in the opposite direction and dropping, and the leading edge of the sheet collides with the arm while the second size sheet, which is larger than the first size, receives the sheet conveying force from the discharge section. The sheet and the arm at the collision position at the shortest distance from the discharge unit to the position where the arm collides with the sheet front end so that the movement of the sheet in the discharge direction stops after the sheet passes through the bottom and the rear end of the sheet passes through the discharge unit. Eggplant Degrees and is arranged to be selected,
In the paper discharge tray, the first size sheet dropped on the paper discharge tray is accumulated with an inclination to the upstream side of the free end of the arm, and the second size sheet whose tip passes under the free end of the arm A sheet deposition apparatus in which a position and an inclination shape with respect to an arm are selected and disposed so as to be deposited while being pressed by a free end. The arm is configured to receive a repulsive force from the arm by the action of its own weight, flexibility or both when the tip of the discharged sheet collides with the arm,
After the leading edge of the sheet collides with the arm in a state where the first size sheet does not receive the conveying force from the discharging section, the sheet falls while decreasing the moving speed in the discharging direction or moving in the opposite direction. The traveling direction of the leading edge of the sheet that collides with the arm moves toward the arm so that the leading edge of the sheet descends and passes under the free end of the arm after the leading edge of the sheet collides with the arm while the sheet receives the conveying force from the discharge unit. 2. The sheet stacking apparatus according to claim 1, wherein an angle formed with respect to the arm, a weight of the arm, a flexibility, or both are selected.   The arm support portion is configured so that the position of the arm support portion relative to the discharge portion can be selected so that the shortest distance from the discharge portion to the position where the sheet collides with the arm can be set according to the length of the first size sheet. The sheet depositing apparatus according to claim 1.   The sheet stacking portion of the paper discharge tray has an inclined portion such that when a sheet having a size equal to or smaller than the first size falls on the paper discharge tray, the sheet is stacked with the rear end approaching the regulating member side by the weight of the sheet. The sheet deposition apparatus according to claim 1.   The arm is disposed so as to collide with a central portion of a leading edge side of the discharged sheet, or disposed so as to collide with two points that are equidistant from the central portion of the leading edge side. Item 2. The sheet deposition apparatus according to Item 1. An image forming apparatus comprising the sheet deposition apparatus according to claim 1.

Images