JP4667191B2 - Paper discharge mechanism and image forming apparatus - Google Patents

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet discharge mechanism that is used in an apparatus for processing sheets such as an image forming apparatus, and stacks and stores processed sheets outside the apparatus, and an image forming apparatus including the sheet discharge mechanism. .

  In an apparatus that processes paper such as an image forming apparatus, processed paper is discharged from the discharge port to the outside of the apparatus using a pair of discharge rollers, and is stacked on a discharge tray mounted on the outer wall of the apparatus. And store. The upper surface of the paper discharge tray is inclined so that the downstream side in the paper discharge direction is positioned higher than the upstream side. An extension line in the paper discharge direction inside the apparatus intersects an intermediate portion on the upper surface of the paper discharge tray. As the leading edge moves away from the paper discharge roller, the lower surface is discharged so that the lower surface rubs against the upper surface of the paper discharge tray or the uppermost paper stored in the paper discharge tray due to the balance between its own weight and rigidity. .

  Friction between the bottom surface of the paper being discharged and the top surface of the paper output tray or the top surface of the uppermost paper reduces the paper discharge speed, and aligns the positions of multiple sheets in the paper output tray. Store in. The position where the paper passing through the paper discharge roller contacts the top surface of the paper discharge tray or the top surface of the uppermost paper is set so that the length from the outer wall of the device is the smallest paper length that can be processed by the device. It is known that the consistency of the storage positions of a plurality of sheets in a paper tray is improved.

Also, in a device with a high processing speed, the paper discharge tray can be moved up and down, and as the number of sheets discharged from the device increases, the paper discharge tray is sequentially lowered from the initial position so that a large number of sheets can be stored. I have to. The initial position of the paper discharge tray in this case is a position where an extension line in the paper discharge direction inside the apparatus intersects with an intermediate portion on the upper surface of the paper discharge tray (for example, see Patent Document 1).
JP 2003-192225 A

  However, if the initial position of the up and down discharge tray is set to a position where the extension line in the discharge direction of the paper in the apparatus intersects the intermediate portion on the upper surface of the discharge tray, the discharge speed is increased when the processing speed in the apparatus is further increased. There is a problem that paper cannot be properly stored in the tray.

  For example, the image forming speed in the image forming apparatus is 40 to 60 sheets / min until several years ago when A4 size paper is conveyed in a direction parallel to the short side, but is currently the fastest and is 100 to 120. There is something to do per sheet. In this case, the sheet conveyance speed is approximately 450 to 650 mm / sec.

  When the sheet transported at such a high speed is discharged to the discharge tray whose initial position is a position where the extension line in the discharge direction of the sheet inside the apparatus intersects the intermediate portion on the upper surface of the discharge tray, The uppermost sheet may be displaced when contacting the upper surface of the sheet, and the speed of the discharged sheet is not sufficiently reduced depending on the contact with the upper surface of the uppermost sheet. As a result, the paper drops from the paper discharge tray or the discharge order changes, and the paper cannot be properly stored in the paper discharge tray.

  An object of the present invention is to set the initial position of a vertically movable discharge tray to a position where an extension line in the discharge direction of the paper inside the apparatus intersects with the downstream side of the discharge direction in the discharge tray, and discharges the paper upward. Accordingly, a paper discharge mechanism capable of stacking and storing a plurality of sheets discharged at high speed in a discharge tray in a state of being aligned with each other, and an image forming apparatus including the paper discharge mechanism are provided. There is to do.

  As means for solving the above problems, the present invention has the following configuration.

(1) a paper discharge tray for stacking and storing paper on an inclined upper surface with the downstream side in the paper discharge direction above the upstream side;
A discharge roller configured to press a pair of upper and lower rollers whose hardness of the upper roller is higher than that of the lower roller in a direction perpendicular to the axial direction, and discharges the sheet toward the discharge tray;
The sheet discharge tray is arranged such that an extension line in the sheet conveyance direction until reaching the sheet discharge roller intersects with the downstream end of the upper surface of the sheet discharge tray in the discharge direction. It is characterized by doing.

In this configuration, the downstream side in the paper discharge direction is formed by a paper discharge roller configured by pressing a pair of upper and lower rollers whose upper roller hardness is higher than that of the lower roller in a direction orthogonal to the axial direction. Paper discharge that has an upper surface that is inclined upward from the upstream side and that is arranged so that the extension line in the paper transport direction until it reaches the paper discharge roller intersects the downstream end of the upper surface of the paper discharge tray in the discharge direction. Paper is ejected to the tray.

The pressure-contact portion of the upper and lower rollers in the paper discharge roller has a shape that protrudes downward due to the hardness difference between the upper and lower rollers. As a result, the paper is discharged obliquely upward when passing through the paper discharge roller. The upper surface of the paper discharge tray is inclined with the downstream side in the paper discharge direction set to be higher than the upstream side, and the extended line in the paper transport direction until reaching the paper discharge roller is the upper surface of the paper discharge tray in the discharge direction. It arrange | positions so that it may cross | intersect the downstream edge part . Therefore, the front edge of the paper discharged by the paper discharge roller does not contact the upper surface of the paper discharge tray or the upper surface of the uppermost paper among the paper stored in the paper discharge tray.

(2) The discharge tray is arranged at a position where an extension line in the transport direction intersects with a downstream end portion of the upper surface of the discharge tray in the discharge direction .

In this configuration, the extension line in the sheet conveyance direction until reaching the sheet discharge roller intersects the downstream end of the upper surface of the sheet discharge tray in the discharge direction . Therefore, the upper surface of the paper discharge tray is located sufficiently below the paper conveyance direction until it reaches the paper discharge roller, and the front edge of the paper discharged obliquely upward by the paper discharge roller is the upper surface of the paper discharge tray. Or, it does not come into contact with the upper surface of the uppermost sheet among the sheets stored in the sheet discharge tray.

(3) An elevating mechanism for raising and lowering the paper discharge tray within a predetermined range, a sensor for detecting the upper surface position of the uppermost paper among the paper stored on the upper surface of the paper discharge tray, and a detection result of the sensor A control unit that operates the lifting mechanism so that the extension line in the transport direction intersects with the downstream end of the upper surface of the uppermost sheet in the discharge direction, and lowers the discharge tray by a predetermined amount; Is further provided.

In this configuration, when a plurality of sheets are continuously discharged, the uppermost sheet in the discharge direction is the extension line in the transport direction until reaching the discharge roller among the sheets stored in the discharge tray. The sheet discharge tray is lowered by a predetermined amount so as to cross the downstream end of the upper surface of the sheet. Therefore, even when a large number of sheets are continuously ejected, the top surface of the uppermost sheet among the sheets stored in the sheet discharge tray is always in the direction in which the sheet is conveyed until it reaches the sheet discharge roller. On the other hand, the front end of the sheet discharged sufficiently by the sheet discharge roller does not contact the upper surface of the uppermost sheet among the sheets stored in the sheet discharge tray.

  According to the present invention, the following effects can be obtained.

(1) Discharging the paper from the paper discharge roller obliquely upward by causing the pressure contact portion of the upper and lower rollers of the paper discharge roller to have a shape that protrudes downward due to the hardness difference between the upper and lower rollers. Can do. This prevents the front edge of the paper ejected by the paper ejection roller from contacting the top surface of the paper ejection tray or the top surface of the paper stored in the paper ejection tray, and ejects the paper at high speed. Even in such a case, a plurality of sheets can be stacked and stored on the sheet discharge tray in a state of being accurately aligned.

(2) By disposing the discharge tray so that the extension line in the conveyance direction of the paper until it reaches the discharge roller intersects the downstream end of the conveyance direction on the upper surface of the discharge tray, the upper surface of the discharge tray is The sheet can be positioned sufficiently lower than the sheet conveyance direction until the sheet discharge roller is reached. This reliably prevents the front edge of the paper discharged obliquely upward by the paper discharge roller from contacting the top surface of the paper discharge tray or the top surface of the paper stored in the paper discharge tray. In addition, even when the sheets are discharged at a high speed, a plurality of sheets can be stacked and stored on the sheet discharge tray in an accurately aligned state.

(3) When a plurality of sheets are continuously discharged, an extension line in the conveyance direction until reaching the sheet discharge roller is an extension line of the uppermost sheet among the sheets stored in the sheet discharge tray. By lowering the paper discharge tray by a predetermined amount so as to cross the downstream side of the middle part, the top surface of the uppermost paper among the paper stored in the paper discharge tray is always reached until it reaches the paper discharge roller. It can be positioned sufficiently below the paper transport direction. This prevents the front edge of the paper ejected by the paper ejection rollers from contacting the top surface of the topmost paper among the paper stored in the paper ejection tray, and ensures that a large number of paper ejected at high speed can be accurately The sheets can be stacked and stored on the paper discharge tray in an aligned state.

  An example of an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of an image forming apparatus 10 provided with a paper discharge mechanism 1 according to an embodiment of the present invention. The image forming apparatus 10 includes an image reading unit 100, an image forming unit 200, and a paper feeding unit 300 provided with the document reading device 1 of the present invention.

  The image reading unit 100 includes a CCD (Charge Coupled Device) reading unit 111, a document table 112, a light source unit 113, a mirror unit 114, and a document conveying device 115. The document transport device 115 transports documents one by one to the upper surface of the document table 112. The CCD reading unit 111 includes an imaging lens and a CCD image sensor. The light source unit 113 is equipped with a light source, a mirror, and the like. The mirror unit 114 has a pair of mirrors.

  The light source unit 113 has a speed V, and the mirror unit 114 has a speed V / 2. The light source unit 113 reciprocates in the sub-scanning direction on the lower surface of the document table 112, and the reflected light on the entire image surface of the document on the document table 112 has an optical path length. It is kept constant and guided to the CCD reading unit 111.

  The image forming unit 200 is disposed below the image reading unit 100. The image forming unit 200 includes a photosensitive drum 211, a charger 212, a laser writing unit 213, a developing device 214, a transfer unit 215, a cleaner 216, and a fixing unit 217.

  The photosensitive drum 211 has a photosensitive layer on the surface and is rotatably supported. The charger 212 charges the surface of the photosensitive drum 211 to a predetermined potential. The laser writing unit 213 forms an electrostatic latent image by irradiating the surface of the photosensitive drum 211 with laser light modulated by image data. The developing device 214 supplies toner to the electrostatic latent image formed on the surface of the photosensitive drum 211 to visualize the toner image. The transfer unit 215 transfers the toner image carried on the surface of the photosensitive drum 211 onto the paper. The cleaner 216 collects excess toner remaining on the surface of the photosensitive drum 211. The fixing unit 217 heats and presses the paper on which the toner image is transferred, and fixes the toner image on the surface of the paper.

  Image data read from the original by the image reading unit 100 is sent to the image forming unit 200. The image data is subjected to predetermined image processing in the image processing unit of the image forming unit 200, temporarily stored in the memory of the image processing unit, read out from the memory according to an output instruction, and transferred to the laser writing unit 213. Is done.

  The sheet feeding unit 300 is disposed below the image forming unit 210. The paper feed unit 300 includes paper trays 301 to 304, a manual feed tray 305, a large-capacity paper feed cassette 306, and a paper discharge tray 11. Each of the paper trays 301 to 304 and the large-capacity paper feed cassette 306 stores a plurality of sheets having the same size and quality. The paper discharge tray 11 stacks and stores sheets that have undergone image formation processing.

  In the paper feed unit 300, conveyance paths 311 to 318 are formed. The conveyance path 311 is formed between the registration roller 321 and the paper discharge roller 12 via the photosensitive drum 211 and the transfer unit 215. The conveyance path 314 guides the sheet fed from the sheet tray 301 to the registration roller 321. When the image is formed on both sides of the paper, the conveyance path 312 reverses the front and back of the paper on which the image is formed on the first surface. The conveyance path 313 guides the sheet that is reversed in the front-rear direction in the conveyance path 312 to the conveyance path 314. The conveyance path 315 guides the sheet fed from the sheet tray 302 to the conveyance path 314. The conveyance record 316 guides the sheet fed from the sheet trays 303 and 304 to the conveyance path 314. The conveyance path 317 guides the sheet fed from the manual feed tray 305 to the conveyance path 314. The conveyance path 318 guides the sheet fed from the large capacity sheet cassette 306 to the conveyance path 314.

  FIG. 2 is a diagram showing a configuration of the paper discharge mechanism 1. The paper discharge mechanism 1 includes a paper discharge tray 11, a paper discharge roller 12, a sensor 13, a motor 14, a driving roller 15, a driven roller 16, and a belt 17.

  The paper discharge tray 11 is supported by a support member 18 so as to be movable up and down with respect to the apparatus outer wall 101. The paper discharge roller 12 is configured such that an upper roller 12A and a lower roller 12B are pressed against each other in a direction orthogonal to the axial direction under a predetermined pressure. The sheet passes between the upper roller 12A and the lower roller 12B. A sensor 13 and a motor 14 are fixed to the support member 18, and a driven roller 16 is pivotally supported. The drive roller 15 is fixed to the rotating shaft of the motor 14. A belt 17 is stretched between the driving roller 15 and the driven roller 16. A part of the belt 17 is fixed to the paper discharge tray 11. By driving the motor 14 in the forward or reverse direction to rotate the driving roller 15, the paper discharge tray 11 is lowered or raised.

  The motor 14, the driving roller 15, the driven roller 16, the belt 17 and the support member 18 correspond to the lifting mechanism of the present invention. It should be noted that the lifting mechanism can have another configuration on condition that the discharge tray 11 is lifted and lowered within a predetermined range.

As shown in FIG. 2, the paper discharge tray 11 is arranged with the position where the extension line 19 in the paper transport direction until reaching the paper discharge roller 12 intersects the downstream end 11 </ b> A on the upper surface of the paper discharge tray 11 as the upper limit position. Has been. The sensor 13 detects the upper surface of the uppermost sheet when a predetermined number of sheets are stacked and stored on the upper surface of the paper discharge tray 11 disposed at the upper limit position.

  The upper limit position of the paper discharge tray 11 can be determined according to the most frequently used paper size in the image forming apparatus 10. In other words, the downstream end of the most frequently used paper in the image forming apparatus 10 stored in the paper discharge tray 11 can be set to a position where it intersects the extension line 19 in the paper conveyance direction until the paper discharge roller 12 is reached. .

  A sensor 13 and a motor driver 120 are connected to the control unit 110 of the image forming apparatus 10 via an internal bus 130. The controller 110 outputs drive data to the motor driver 120 based on the detection signal of the sensor 13. The motor driver 120 drives the motor 14 based on the drive data input from the control unit 110.

  FIG. 3 is a diagram showing a configuration of the paper discharge roller 12 of the paper discharge mechanism 1. As an example, in the paper discharge roller 12, the upper roller 12A is made of resin, and the lower roller 12B is made of urethane rubber. Accordingly, the hardness of the upper roller 12A is higher than the hardness of the lower roller 12B, and the press-contact portion between the upper roller 12A and the lower roller 12B has a shape that protrudes downward. Therefore, the sheet is discharged obliquely upward when it passes through the sheet discharge roller 12.

  FIG. 4 is a diagram for explaining a paper discharge state in the image forming apparatus 10. When one sheet 2 is discharged by the sheet discharge mechanism 1, as shown in FIG. 4A, the sheet discharge tray 11 has an upper limit that is lower than the position detected by the sensor 13 by a predetermined amount. Placed in position.

  When a plurality of sheets 3 are sequentially discharged and stacked and stored on the upper surface of the discharge tray 11, and the upper surface of the uppermost sheet is detected by the sensor 3, as shown in FIG. The tray 11 is lowered by a predetermined amount, and a predetermined amount of space is formed between the upper surface of the uppermost sheet and the sensor 3. When the sheet 2 passes through the sheet discharge roller 12, it is discharged obliquely upward as shown in FIG. Thereafter, the sheet 2 is discharged substantially horizontally as shown in FIG.

  When the trailing edge of the sheet 2 being discharged passes through the sheet discharge roller 12, the sheet 2 moves downward in the discharge direction by inertial force and falls downward due to gravity. As a result, as shown in FIG. 4D, the sheet 2 being discharged is a downstream portion in the transport direction on the upper surface of the uppermost sheet 3 inclined with the downstream side in the transport direction above the upstream side. To touch. Thereafter, the sheet 2 becomes parallel to the uppermost sheet 3 by gravity, and further moves to the downstream side in the transport direction while reducing the inertial force by friction with the sheet 3.

  When the inertial force acting on the paper 2 is sufficiently reduced due to the friction with the paper 3 and the gravity acting on the paper 2 becomes larger than the inertial force, the paper 2 is separated from the paper as shown in FIG. 3 moves in the direction opposite to the discharge direction along the upper surface of 3. As shown in FIG. 4F, the sheet 2 stops moving in the direction opposite to the discharge direction while the rear end abuts against the wall surface of the support member 18, and the sheet 2 is stored on the sheet discharge tray 11. Thus, they are stacked and stored at a position aligned with the sheet 3.

  As described above, the paper discharge tray 11 is disposed below the conventional one, and the paper discharge direction of the paper by the paper discharge roller 12 is set to be higher than the paper conveyance direction on the front side of the paper discharge roller 12. Out of the sheets already stored on the tray 11, the sheet being discharged is already stored on the discharge tray 11 while preventing the leading end of the discharged sheet from contacting the top surface of the uppermost sheet. It can be stored on the paper at a position aligned with the paper.

  In other words, in order to prevent the leading end of the paper being discharged from coming into contact with the upper surface of the uppermost paper among the papers already stored on the paper discharge tray 11, the paper discharge tray 11 is disposed as low as possible. do it. However, in this case, the number of sheets stored on the paper discharge tray 11 is reduced. In addition, the paper being discharged rotates with the leading edge down and is stored in a curved state, or the front and back surfaces are reversed.

  Therefore, by making the paper discharge direction by the paper discharge roller 12 upward, the paper discharge tray 11 can be arranged at a position where the extended line in the paper conveyance direction intersects with the downstream side of the middle portion of the upper surface. The topmost sheet among the sheets that are already stored on the discharge tray 11 while the leading edge of the sheet being discharged is prevented from decreasing the number of sheets stored in the tray 11, curving the discharged sheet, and reversing the front and back surfaces. Thus, a plurality of sheets can be stacked and stored in the discharge tray 11 in an aligned state.

  In this embodiment, the paper discharge mechanism of the present invention is applied to an image forming apparatus that performs image forming processing on paper. However, the paper discharge mechanism of the present invention is also applied to an apparatus that performs other processing on paper. Can be applied as well.

1 is a diagram illustrating a schematic configuration of an image forming apparatus 10 including a paper discharge mechanism 1 according to an embodiment of the present invention. FIG. 3 is a diagram illustrating a configuration of the paper discharge mechanism 1. FIG. 3 is a diagram illustrating a configuration of a paper discharge roller 12 of the paper discharge mechanism 1. FIG. 3 is a diagram illustrating a paper discharge state in the image forming apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Paper discharge mechanism 10 Image forming apparatus 11 Paper discharge tray 12 Paper discharge roller 12A Upper roller 12B Lower roller 13 Sensor 14 Motor (elevating mechanism)
15 Drive roller (elevating mechanism)
16 Followed roller (elevating mechanism)
17 Belt (elevating mechanism)
18 Support member (elevating mechanism)
110 Control unit

Claims (4)

A paper discharge tray for stacking and storing paper on an inclined upper surface with the downstream side in the paper discharge direction positioned above the upstream side;
A discharge roller configured to press a pair of upper and lower rollers whose hardness of the upper roller is higher than that of the lower roller in a direction perpendicular to the axial direction, and discharges the sheet toward the discharge tray;
The sheet discharge tray is arranged such that an extension line in the sheet conveyance direction until reaching the sheet discharge roller intersects with the downstream end of the upper surface of the sheet discharge tray in the discharge direction. A paper discharge mechanism.   The paper discharge mechanism according to claim 1, wherein the paper discharge tray is disposed at a position where an extension line in the transport direction intersects with a downstream end portion of an upper surface of the paper discharge tray in the discharge direction. Based on a detection result of the sensor, a lifting mechanism that raises and lowers the discharge tray within a predetermined range, a sensor that detects an upper surface position of the uppermost sheet among sheets stored on the upper surface of the discharge tray, and A control unit that operates the elevating mechanism so that the extension line in the transport direction intersects the downstream end of the upper surface of the uppermost sheet in the discharge direction to lower the discharge tray by a predetermined amount. The paper discharge mechanism according to claim 1, wherein the paper discharge mechanism is provided.   An image forming apparatus comprising the paper discharge mechanism according to claim 1, wherein the paper after image formation processing is discharged to the paper discharge tray.

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