JP4491359B2 - Sheet conveying apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a sheet conveying apparatus and an image forming apparatus.

  In an image forming apparatus such as a printer, a copier, a facsimile machine, or a multi-function machine having at least two of these functions, an apparatus having a double-sided image forming function and a post-processing function after image formation is used. A switching claw is provided as a means for switching the destination of delivery. Most of the conventional switching claws are driven by solenoids, but with recent image forming devices, as productivity has increased, sheet conveyance speed has been increased, and sheet spacing during continuous printing has been reduced. The operation of the switching claw solenoid has been unable to keep up with restrictions such as response time.

JP 2004-051345 A

Therefore, in order to perform the switching of the conveyance path at a higher speed, it has been proposed to drive the switching claw with a stepping motor as shown in Patent Document 1.
However, in a device that uses a stepping motor to drive the switching claw, if the machine suddenly stops due to a jam or cover being opened or the power is shut off, not only the sheet being conveyed stops, The switching claw also stops at an arbitrary position. In this case, when trying to process the sheet left in the machine, the switching claw in an indefinite position prevents the sheet from being processed, and the sheet may be caught or torn.

  SUMMARY OF THE INVENTION In view of the above-described conventional problems, the present invention provides a sheet conveying apparatus and an image forming apparatus capable of switching sheet conveying paths at high speed and having improved maintainability such as processing of sheets left in the apparatus. The purpose is to do.

  In order to solve the above problems, the present invention provides a sheet conveying apparatus having a conveying path switching unit that switches a conveying path of a sheet and a driving unit that drives the conveying path switching unit, wherein the driving unit switches the conveying path. It is possible to move and stop the means to an arbitrary position within the movable range, and when the driving means is stopped together with the sheet conveying apparatus, the conveying path switching means is moved from the stop position to a predetermined position. It is said.

  In the sheet conveying apparatus of the present invention, the driving unit includes a moving unit that releases the driving when the sheet conveying itself stops and moves the conveying path switching unit to the predetermined position when the driving is released. It is effective.

  Furthermore, in the sheet conveying apparatus of the present invention, the moving means is a means for biasing the conveying path switching means to a predetermined position with a weak moving force sufficient to move the conveying path switching means. It is effective.

  Furthermore, in the sheet conveying apparatus of the present invention, the conveying path switching means is effective when switching a sheet carried from a predetermined direction to a plurality of conveying paths.

  Furthermore, in the sheet conveying apparatus of the present invention, the conveying path switching means carries a sheet from a predetermined direction into a reversing conveying path capable of conveying the sheet bidirectionally, and the sheet reversed and carried out from the reversing conveying path is set as the carrying-in direction. Is effective when guided in another predetermined direction.

Furthermore, in the sheet conveying apparatus of the present invention, it is effective that the driving means is a stepping motor.
In order to solve the above problems, the present invention is characterized by including the sheet conveying apparatus according to any one of claims 1 to 3.

  According to the configuration of the first aspect, the driving unit that drives the conveyance path switching unit can move and stop the conveyance path switching unit to an arbitrary position within the movable range, but when the sheet conveyance device stops, Since the transport path switching means moves to a predetermined position, the sheet remaining in the apparatus can be easily processed.

  According to the configuration of the second aspect of the present invention, since the driving of the conveyance path switching unit is released when the sheet conveyance apparatus is stopped, and another unit for moving the conveyance path switching unit to a predetermined position is provided. Even when the apparatus is stopped due to clogging or an abnormality in the apparatus, the conveyance path switching means moves to a predetermined position, so that the sheet remaining in the apparatus can be easily processed.

  According to the third aspect of the present invention, since the moving means is an urging means having a weak force sufficient to move the conveyance path switching means, the sheet may be present at the position of the conveyance path switching means when the apparatus is stopped. Does not damage the sheet or interfere with the processing of the sheet.

  According to the configuration of the fourth aspect, since the means of the first to third aspects is used as the conveyance path switching means for switching the sheet carried in from a predetermined direction to the plurality of conveyance paths, the sheet having a plurality of discharge destinations. The operability of the transport device can be improved.

  According to the configuration of claim 5, the sheet includes a reversing conveyance path that can be conveyed in both directions, and a sheet that is carried into the reversing conveyance path from a predetermined direction and is reversed and carried out from the reversing conveyance path is different from the loading direction. Since the means according to claims 1 to 3 is used as the conveying path switching means for guiding in a predetermined direction, the operability of the sheet conveying apparatus having the reverse conveying function can be improved.

  According to the configuration of the sixth aspect, since the stepping motor is used as the means for driving the conveyance path switching means, it is possible to cope with high productivity and high speed sheet conveyance apparatus and improve the operability of the sheet conveyance apparatus. Can do.

  According to the configuration of the seventh aspect, it is possible to surely switch the sheet conveyance path for high speed and high productivity, and to easily perform sheet processing such as when a paper jam occurs, thereby improving operability. it can.

FIG. 1 is a schematic diagram showing a sheet conveyance path of a color image forming apparatus provided with a sheet conveyance apparatus according to the present invention.
In FIG. 1, reference numeral 1 denotes an image forming unit, and the image forming unit 1 has a conveyor belt 2 wound around four rollers. The conveyor belt 2 rotates counterclockwise with one of the rollers as a driving roller. When driven, the vehicle is driven in the direction of arrow A. Drum-shaped photoconductors 3a, 3b, 3c, and 3d are arranged on the upper running side of the conveyor belt 2 as first to fourth image carriers, and a magenta toner image, a cyan toner image, A yellow toner image and a black toner image are respectively formed.

  When a toner image is formed on each of the first to fourth photoreceptors 3, a sheet P as a sheet is fed from a sheet feeding device 4 provided below the image forming unit 1 so as to be synchronized with the toner image. The toner image is transferred.

  Then, the paper P onto which all the toner images are transferred is fixed as a permanent image by the fixing device 5 and arrives at the first branch portion. The first branch portion is provided with a switching claw 6 as a conveyance path switching means, and the switching claw 6 selects whether the paper P is an upper conveyance path or a lower conveyance path. As shown in FIG. 2A, when the upper conveyance path is selected, the paper P is discharged to the back surface of the paper discharge unit 7. As shown in FIG. 2B, when the lower transport path is selected, the paper P is transported to the paper reversing device 10 for duplex printing.

  The sheet reversing device 10 draws the sheet P conveyed from the image forming unit 1 through the carry-in path 11 into the switchback conveyance path 12, detects the sheet P by the sensor 14 in the switchback conveyance path 12, and detects a predetermined position. Is temporarily stopped, conveyed in the reverse direction, and sent to the carry-out path 13 for feeding the paper P to the image forming unit. At this time, a switching claw 15 for switching the conveyance path is provided in order to send the reversely conveyed paper P to the carry-out path 13 without returning to the carry-in path 11.

  In such an image forming apparatus, when images are continuously formed on both sides of the paper P, it is necessary to switch the transport destination between the paper discharge path and the refeed path and to reverse the paper within a short paper interval. As the productivity of the image forming apparatus is improved, the paper conveyance speed is higher and the paper interval is shorter. For this reason, the switching claw 6 for switching the transport destination of the paper discharge path and the refeed path and the switching claw 15 for guiding the reversely transported paper to the carry-out path 13 after the paper is carried into the switchback transport path 12 are shortened. It is necessary to move with time, and a stepping motor 20 with good responsiveness is used to drive the switching claws 6 and 15.

  However, in the device in which the switching claws 6 and 15 are driven by the stepping motor 20, if the power is suddenly turned off by an accident or the like, the switching claws stop at an indefinite position due to the stop of the stepping motor 20, and this is the case. It has been described above that it may interfere with processing.

  Therefore, in the present invention, as shown in FIG. 4, the switching claw 6 is provided with a spring 32 that biases the claw so that the attitude of the claw becomes a predetermined position. In this case, the switching claw 6 has one end of a spring 32 locked to a machine frame not shown in the figure fixed to the tip of an arm 33 fixed to the shaft 31, and the switching claw 6 is rotated clockwise. Energizing the rotational force. 4 is a perspective view of the switching claw 6, but in this apparatus, the switching claw 15 is configured in substantially the same manner as the switching claw 6, that is, the urging force of the spring 32 is applied. Even if the stepping motor 20 is de-energized when the power is turned off, the switching claws 6 and 15 are moved to a predetermined position by the action of the spring 32.

  In the case of the switching claw 6 for switching the transport destination between the paper discharge path and the refeed path, the predetermined position here is a position for guiding the paper to the paper discharge path to the paper discharge tray which is a standard transport destination. In the case of the switching claw 15 of the sheet reversing device 10, it is the retreat position when the sheet is carried from the carry-in path to the switchback conveyance path.

  When the image forming apparatus is activated, the stepping motor that drives the switching claws 6 and 15 is excited. The switching claw 6 for switching the transport destination between the paper discharge path and the refeed path is switched according to the instruction of the transport destination whether the paper is discharged to the paper discharge unit 7 or transported to the refeed path for duplex printing. Is moved at a predetermined timing (FIG. 2).

  The switching claw 15 of the sheet reversing device 10 is fixed at the retracted position in the default state, and a conveyance path for guiding the sheet P from the carry-in path 11 to the switchback conveyance path 12 is secured. Since the sheet reversing device 10 reverses the sheet within a short sheet interval, after the image formation on the sheet is completed, the conveyance speed of the carry-in path 11 is increased and the sheet is fed into the switchback conveyance path 12 (FIG. 3 ( a)). In the switchback conveying path 12, the sensor 14 detects the leading edge of the paper, and after the trailing edge of the paper passes through the switching claw 15 from the paper length information, the switching claw 15 is moved from the retracted position to a position for guiding the paper to the carry-out path 13. In addition, the sheet is stopped after a predetermined time (see FIG. 3B). The switchback transport path 12 transports the paper in the reverse direction and feeds it to the carry-out path 13 (see FIG. 3C). The sensor 14 detects the rear edge of the paper, and the rear edge of the paper switches the claw 15 from the paper length information. The switching claw 15 is again moved to the retracted position at the time of removal.

  If a paper jam or abnormality occurs during image formation or paper conveyance, the apparatus stops and the stepping motor 20 that drives the switching claws 6 and 15 is also turned off. At this time, the position of the switching claws 6 and 15 is not known, but when the stepping motor 20 is de-energized, the switching claws 6 and 15 are moved to the predetermined positions by the force of the spring 32. .

  As described above, the stepping motor 20 for driving the switching claws 6 and 15 can move and stop the switching claws 6 and 15 to an arbitrary position within the movable range. However, when the sheet conveying device is stopped, the switching claws 6 and 15 can be moved. Since the papers 6 and 15 are moved to a predetermined retreat position, the paper remaining in the apparatus can be easily processed. Since the switching claws 6 and 15 return to the predetermined retracted position even when the apparatus stops unexpectedly in this way, the switching claws 6 and 15 become an obstacle when processing the paper remaining in the apparatus. Will never be difficult.

  Since the biasing force of the spring 32 is weak enough to move the no-load switching claw, even when the paper is on the switching claw, the stepping motor is de-energized and the switching claw is turned off by the spring force. The paper will not be damaged by trying to move. In the above embodiment, the image forming apparatus having the double-sided printing function has been described. However, when the image forming apparatus has a face-up discharge tray and a face-down discharge tray, or a sheet after image formation such as a discharge apparatus having a plurality of bins. The same applies to the switching claw for selecting and switching the paper discharge destination. In addition, the paper reversing device is not only for double-sided printing, but is also used when discharging the paper on which the image has been formed upside down to the paper discharge tray, when reversing the paper and discharging it to the post-processing device, etc. It also applies to reversing devices.

1 is a schematic configuration diagram illustrating a conveyance path of an image forming apparatus according to the present invention. (A), (b) is explanatory drawing which shows the delivery direction of the paper by the action | operation of a switching claw. (A), (b), (c) is explanatory drawing which shows the sheet | seat delivery direction by the action | operation of the switching claw in a sheet reversing apparatus. It is an external appearance perspective view of a switching nail.

Explanation of symbols

6, 15 Switching claw 20 Stepping motor 32 Spring

Claims (7)

In a sheet conveying apparatus having a conveying path switching unit that switches a conveying path of a sheet, and a driving unit that drives the conveying path switching unit.
The drive means can move and stop the transport path switching means to an arbitrary position within the movable range, and when the drive means is stopped together with the sheet transport apparatus, the transport path switching means is moved from the stop position. A sheet conveying apparatus that moves to a predetermined position.   2. The drive unit according to claim 1, further comprising a moving unit that releases the driving when the sheet conveyance itself stops and moves the conveyance path switching unit to the predetermined position when the driving is released. Sheet conveying device.   3. The sheet according to claim 2, wherein the moving unit is a unit that urges the transport path switching unit to a predetermined position with a weak moving force sufficient to move the transport path switching unit. Conveying device.   The sheet conveying apparatus according to any one of claims 1 to 3, wherein the conveying path switching unit switches a sheet carried from a predetermined direction to a plurality of conveying paths.   The conveyance path switching means is carried into a reverse conveyance path capable of conveying a sheet bidirectionally from a predetermined direction, and guides the sheet reversed and carried out from the reverse conveyance path in a predetermined direction different from the carry-in direction. The sheet conveying apparatus according to any one of claims 1 to 3.   The sheet conveying apparatus according to claim 1, wherein the driving unit is a stepping motor.   An image forming apparatus comprising the sheet conveying device according to claim 1.

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