JP4760943B2 - Conveyance path switching device and image forming apparatus using the same - Google Patents

Description

  The present invention relates to a conveyance path switching device and an image forming apparatus using the same.

  Conventionally, as a technique related to the transport path switching device, for example, a technique disclosed in Japanese Patent Application Laid-Open No. 2005-41635 has been proposed.

An image forming apparatus according to JP 2005-41635 A includes a developing unit that forms a developer image on an image forming surface of a sheet,
A fixing unit for fixing the developer image to the paper by heating the paper on which the developer image is formed by the developing unit in a pressurized state at a fixing position;
A paper discharge unit for discharging the paper on which the developer image on the image forming surface is fixed at the fixing position of the fixing unit;
An inversion supply unit that inverts the image forming surface of the paper on which the developer image on the image forming surface is fixed at the fixing position of the fixing unit and re-supply the paper to the developing unit. A forming device,
The fixing unit guides the paper to the paper discharge unit while being pushed up by the paper fixed at the fixing position, and gate means for guiding the paper to the reversal supply unit after passing the paper. ,
Detecting means for detecting the presence or absence of paper pushing up the gate means in accordance with the operation of the gate means;
When transporting the paper that has passed through the gate means to the reversal supply unit side, the paper is once transported to the paper discharge unit side, and after the detection means detects that the paper has passed through the gate means, And a conveying unit that conveys the sheet to the reversal supply unit side.

JP 2005-41635 A

  By the way, a problem to be solved by the present invention is that a conveyance path switching device capable of detecting a conveyance failure of both recording media at the time of single-sided image formation and double-sided image formation by a conveyance path switching member and the use thereof. Another object of the present invention is to provide an image forming apparatus.

That is, according to the first aspect of the present invention, there is provided a discharge conveyance between the fixing unit that fixes the image on the recording medium and the discharge unit that discharges the recording medium toward the outside. Route,
A double-sided transport path through which the recording medium is transported by reversing the transport direction of the recording medium transported toward the outside during double-sided image formation;
It is rotatably disposed opposite to the discharge conveyance path, and protrudes into the discharge conveyance path when the recording medium is not conveyed, and is at a first position that opens the double-side conveyance path, When the recording medium is transported from the fixing unit, the recording medium is rotated by the recording medium toward the second position where the recording medium is retracted from the protruding position, and is transported to the duplex transport path when the double-sided image is formed. And a conveyance path switching member that rotates toward the second position,
Bei example and a detection means for detecting that the transport path switching member is rotated toward the second position,
The conveyance path switching member is disposed in the discharge conveyance path and rotated by the passage of the recording medium, and the operation arm section disposed in the double-side conveyance path and rotated by the passage of the recording medium. , And a part of the operating arm portion constitutes a light shielding plate for operating the detecting means .

Further, the invention described in claim 2 is characterized in that the transport path switching member stops or returns to the first position by its own weight except when the recording medium is rotated. It is a conveyance path | route switching apparatus of Claim 1.
Further, in the invention described in claim 3, the operating arm of the transport path switching member has a contact resistance with the recording medium that fluctuates along a direction intersecting the transport direction of the recording medium depending on the width of the recording medium. As a result, the recording medium is formed in the same shape so as to prevent the skew and the folding of the ear from occurring, and is symmetrical with respect to the central portion along the direction intersecting the recording medium conveyance direction. It is arrange | positioned at this, It is a conveyance path | route switching apparatus of Claim 1 or 2 characterized by the above-mentioned.

Further, the invention described in claim 4 is an image forming means for forming a toner image on one surface of the recording medium,
Fixing means for fixing a recording medium having a toner image formed on the one surface;
Discharging means for discharging the recording medium on which the toner image is fixed by the fixing means to the outside;
A discharge conveyance path between the fixing unit and the discharge unit, through which the recording medium is conveyed;
A double-sided transport path through which the recording medium is transported by reversing the transport direction of the recording medium transported toward the outside during double-sided image formation;
It is rotatably disposed opposite to the discharge conveyance path, and protrudes into the discharge conveyance path when the recording medium is not conveyed, and is at a first position that opens the double-side conveyance path, When the recording medium is transported from the fixing unit, the recording medium is rotated by the recording medium toward the second position where the recording medium is retracted from the protruding position, and is transported to the duplex transport path when the double-sided image is formed. And a conveyance path switching member that rotates toward the second position,
Detecting means for detecting that the transport path switching member is rotated toward the second position;
Bei to give a,
The conveyance path switching member is disposed in the discharge conveyance path and rotated by the passage of the recording medium, and the operation arm section disposed in the double-side conveyance path and rotated by the passage of the recording medium. The image forming apparatus is characterized in that a part of the operating arm portion constitutes a light shielding plate for operating the detecting means .

  According to the first aspect of the present invention, as compared with the case where the present configuration is not provided, the conveyance path switching member detects the conveyance failure of both the recording media during the single-sided image formation and the double-sided image formation. Is possible.

According to the invention described in claim 2, the configuration can be simplified as compared with the case where the present configuration is not provided.
Furthermore, according to the third aspect of the present invention, it is possible to prevent the skew and the ear folding from occurring in the recording medium as compared with the case where this configuration is not provided.

Furthermore, according to the invention described in claim 4 , compared to the case where the present configuration is not provided, the conveyance path switching member detects the conveyance failure of both the recording media during the single-sided image formation and the double-sided image formation. It becomes possible to do.

It is a block diagram which shows the principal part of the monochrome image forming apparatus as an image forming apparatus to which the conveyance path | route switching apparatus which concerns on Embodiment 1 of this invention is applied. 1 is a configuration diagram showing a monochrome image forming apparatus as an image forming apparatus to which a transport path switching device according to Embodiment 1 of the present invention is applied. FIG. It is a perspective view showing a switching gate. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective configuration diagram showing a main part of a monochrome image forming apparatus as an image forming apparatus to which a transport path switching device according to Embodiment 1 of the present invention is applied. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective configuration diagram showing a main part of a monochrome image forming apparatus as an image forming apparatus to which a transport path switching device according to Embodiment 1 of the present invention is applied. It is explanatory drawing which shows operation | movement of the monochrome image forming apparatus as an image forming apparatus to which the conveyance path | route switching apparatus which concerns on Embodiment 1 of this invention is applied. It is explanatory drawing which shows operation | movement of the monochrome image forming apparatus as an image forming apparatus to which the conveyance path | route switching apparatus which concerns on Embodiment 1 of this invention is applied. It is explanatory drawing which shows operation | movement of the monochrome image forming apparatus as an image forming apparatus to which the conveyance path | route switching apparatus which concerns on Embodiment 1 of this invention is applied. It is explanatory drawing which shows operation | movement of the monochrome image forming apparatus as an image forming apparatus to which the conveyance path | route switching apparatus which concerns on Embodiment 1 of this invention is applied. It is explanatory drawing which shows operation | movement of the monochrome image forming apparatus as an image forming apparatus to which the conveyance path | route switching apparatus which concerns on Embodiment 1 of this invention is applied.

  Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1
FIG. 2 is a schematic configuration diagram showing a monochrome image forming apparatus as an image forming apparatus to which the transport path switching apparatus according to the first embodiment of the present invention is applied.

  In FIG. 2, reference numeral 1 denotes a main body of the image forming apparatus. The main body 1 of the image forming apparatus is formed in a substantially rectangular parallelepiped box shape. Inside the image forming apparatus main body 1, a photosensitive drum 2 as an image carrier is disposed slightly to the right of the center of the image forming apparatus. The photosensitive drum 2 is driven in the direction of the arrow by a driving unit (not shown). It is rotationally driven at a predetermined speed. Further, the surface of the photosensitive drum 2 is charged to a predetermined potential by a charging roll 3 and then subjected to image exposure according to image information by an LED exposure device 4 serving as an image exposure means, and electrostatic latent An image is formed. The electrostatic latent image formed on the surface of the photosensitive drum 2 is visualized by the developing device 5 to become a toner image, and the toner image is recorded on a recording sheet 7 as a recording medium by a transfer roll 6 as a transfer unit. Transcribed above. The photosensitive drum 2, the charging roll 3, the LED exposure device 4, the developing device 5 and the transfer roll 6 constitute an image forming unit.

  The recording sheet 7 is fed from a sheet feeding tray 8 as a sheet feeding unit mounted on the bottom of the image forming apparatus main body 1 in a state of being separated one by one by a sheet feeding roll 9 and a separation roll 10 and registered. It reaches the roll 11 and is conveyed by the registration roll 11 to a transfer position where the photoconductive drum 2 and the transfer roll 6 come into contact with each other in synchronization with the toner image on the photoconductive drum 2.

  The recording paper 7 onto which the toner image has been transferred from the photosensitive drum 2 as described above is conveyed to the fixing device 12 as a fixing unit by the conveying force of the photosensitive drum 2 and the transfer roll 6, and the fixing device 12 is heated. The unfixed toner image is fixed on the recording paper 7 by being heated and pressed by the roll 13 and the pressure roll 14. The recording sheet 7 on which the toner image is fixed is transported to a discharge transport path 16 via a switching gate 15 as a transport path switching member, and a discharge roll as discharge means provided in the discharge transport path 16 17 is discharged onto a foldable discharge tray 18 provided on the upper portion of the image forming apparatus main body 1.

  The discharge unit of the fixing device 12 is provided with a discharge transport path 16 for transporting the recording paper 7 from the discharge unit of the fixing device 12 to the discharge roll 17. The switching gate 15 is rotatably provided around the support shaft 43. In a normal state where the recording paper 7 does not pass, the switching gate 15 stops at the first position where the discharge conveyance path 16 is closed by the dead weight (rotational moment) of the switching gate 15 as shown in FIG. The position of the center of gravity is set so that.

  The discharge roll 17 rotates in a normal rotation direction in which the recording paper 7 is discharged onto the discharge tray 18 by a drive motor (not shown) and a reverse direction in which the recording paper 7 is conveyed in a direction opposite to the discharge direction. Is configured to be switchable.

  Further, above the switching gate 15, the rear end of the recording paper 7 that is conveyed from the discharge unit of the fixing device 12 to the discharge roll 17 and is discharged onto the discharge tray 18 by the discharge roll 17 passes through the switching gate 15. A double-sided transport path 19 is provided for transporting the recording paper 7 to the image forming unit again at the time of double-sided image formation when it is opened by the switching gate 15 that has passed and returned to the first position. This double-sided conveyance path 19 is formed so as to communicate with a double-sided conveyance path 20 extending downward along the side surface of the image forming apparatus main body 1 after passing through the upper part of the switching gate 15. In addition, a conveyance roll 21 that conveys the recording paper 7 to the registration roll 11 is provided in the double-side conveyance path 20 that extends downward.

  Then, at the time of double-sided image formation in which images are formed on both the front and back surfaces of the recording paper 7, the recording paper 7 on which the toner image is fixed on one side by the fixing device 12 is discharged through the discharge conveyance path 16 as shown in FIG. When the recording paper 7 is transported to the roll 17 and discharged onto the discharge tray 18 by the discharge roll 17, if the rear end of the recording paper 7 in the transport direction passes through the switching gate 15, the switching gate 15 is moved by its own weight. The discharge path 16 is closed by itself, and the sheet is returned to the first position where the double-sided conveyance path 19 for guiding the recording sheet 7 for double-sided image formation is opened. Note that the switching gate 15 does not necessarily need to block the discharge path 16 and may be any one that can switch the transport path to such an extent that the recording paper 7 does not jam.

  Therefore, the discharge roll 17 is switched in the rotation direction so that the conveyance direction of the recording paper 7 is reversed at the timing immediately after the rear end of the conveyance direction of the recording paper 7 passes the switching gate 15. 7 is transported to the duplex transport path 20 through the duplex transport path 19 formed above the switching gate 15 by the transport force of the discharge roll 17. The recording sheet 7 transported to the double-side transport path 20 is transported along the double-side transport path 20 by the transport roll 21 provided in the double-side transport path 20, and again with the front and back sides reversed. It is conveyed to the resist roll 11.

  The recording paper 7 is in a state in which the surface on which the image is not formed is positioned on the photosensitive drum 2 side and is synchronized with the toner image on the photosensitive drum 2 by the registration roll 11. And the transfer roll 6 are conveyed to a transfer position.

  In FIG. 2, 22 is a cleaning device for cleaning the surface of the photosensitive drum 2, 23 is a control circuit for the image forming apparatus, 24 is a power circuit, and 50 is openable on the right side of the image forming apparatus main body 1. The cover member provided in each is shown.

  Further, as shown in FIG. 1, the fixing device 12 includes a heating roll 13 having a heating source 25 inside, and a pressure roll 14 in pressure contact with the heating roll 13. A peeling claw 26 is disposed on the discharge portion side of the heating roll 13. Furthermore, the housing 27 of the fixing device 12 is disposed so as to cover the outer periphery of the heating roll 13 and the pressure roll 14, and on the inlet side of the nip portion where the heating roll 13 and the pressure roll 14 are in pressure contact with each other, An introduction portion 28 for introducing the recording paper 7 is provided, and a discharge portion 29 for discharging the recording paper 7 is provided on the exit side of the nip portion. A guide chute 30 for guiding the recording paper 7 is disposed on the inlet side of the nip portion.

  The fixing device housing 27 is provided with a sensor 31 as a detecting means for detecting a rotation position as one example of the second position of the switching gate 15 on the side surface on the double-side conveyance path 20 side. It is installed. Note that the second position of the switching gate 15 is switched between when the recording sheet 7 passes a discharge guide 47 described later and when the recording sheet 7 passes a duplex guide 48 described later. The rotation angle of the gate 15 may be different. The sensor 31 is composed of, for example, a photo interrupter. Normally, light emitted from a light emitting element (not shown) can be received by a light receiving element (not shown), and an actuator described later of the switching gate 15 rotates. By blocking the light emitted from the light emitting element, it is detected that the recording paper 7 has passed through the switching gate 15 and the switching gate 15 has moved to the rotation position.

  As shown in FIG. 3, the switching gate 15 intersects one end of the switching unit 41 with a switching unit 41 that switches between the discharging conveyance path 16 and the double-sided conveyance path 19 by a molded product made of synthetic resin or the like. It is integrally formed in the side surface substantially L shape from the action | operation arm part 42 provided so that it might do. Further, as shown in FIG. 4, the switching gate 15 is provided in the vicinity of the upper end portion of the inner surface of the cover member 50 via a support shaft 43 provided at an intersection where the switching portion 41 and the operating arm portion 42 intersect. Is pivotally attached to a shaft support 44 provided on the shaft. The shaft support portion 43 is provided in a state of projecting from both end portions along the longitudinal direction of the switching gate 15.

  Further, as shown in FIGS. 4 and 5, when the cover member 50 is closed at both ends 51 in the longitudinal direction of the fixing device 12, the support shaft 43 of the switching gate 15 is provided on the image forming apparatus main body 1 side. A positioning recess 52 for positioning by fitting the tip is provided, and an accommodation portion 53 in which the shaft support portion 43 is accommodated.

  As shown in FIG. 3, the switching unit 41 of the switching gate 15 integrates a plurality of switching plates 45 formed in a flat plate shape at predetermined intervals by a connecting plate 46 formed in a side curved shape. It is connected and configured. These switching plates 45 are arranged so as to stand up and down in the up-down direction and in the conveyance direction of the recording paper 7, and only the edge portion positioned at the upper end of the switching plate 45 contacts the recording paper 7. By doing so, the contact resistance with the recording paper 7 is reduced. The plurality of switching plates 45 are all formed in the same shape, and the discharge guide portion 47 provided on the lower surface on the front end side in the recording paper discharge direction, and the acute angle with the front end portion of the discharge guide portion 47. Are formed so as to form an obtuse angle with a curved curved double-sided guide part 48 that forms the entire upper edge part of the switching plate 45 and a lower end part projecting downward of the discharge guide part 47. And an opening guide portion 49 for guiding the switching gate 15 when the cover member 50 is opened.

  On the other hand, as shown in FIG. 3, the operating arm portion 42 of the switching gate 15 includes a flat plate 55 provided corresponding to the same position as the switching plate 45 except for the central portion. They are arranged so as to intersect with each other at a predetermined angle. The operating arm portion 42 is formed in a shape in which the side surface 56 on the double-side conveyance path 20 side protrudes downward, and the side surface 56 of the operating arm portion 42 has the sensor as shown in FIG. This is an actuator for actuating 31.

  Note that the switching portion 41 and the operating arm portion 42 of the switching gate 15 change depending on the width of the recording paper 7 and the contact resistance with the recording paper 7 varies along the direction intersecting the conveyance direction of the recording paper 7. In addition, the recording paper 7 is formed in the same shape so as not to be skewed or so-called “dog-ear”, and the left and right sides with respect to the central portion along the direction intersecting the conveyance direction of the recording paper 7. They are arranged symmetrically. Moreover, the flat plate 55 which operates the sensor 31 among the said operation | movement arm parts 42 is only the flat plate 55 located in the one side of a center part, for example.

  With the above configuration, in the image forming apparatus according to this embodiment, the recording member for both the single-sided image formation and the double-sided image formation is formed by the switching member provided in the discharge unit of the fixing unit as follows. It is possible to detect a conveyance failure.

  That is, in this image forming apparatus, as shown in FIG. 2, a toner image is formed on the photosensitive drum 2 according to the image information, and the toner image formed on the photosensitive drum 2 is transferred by the transfer roll 6. After the transfer onto the recording paper 7, the recording paper 7 on which the toner image has been transferred is heated and pressed by the fixing device 12 to be fixed. Then, the recording sheet 7 on which the toner image is fixed is conveyed to the discharge roll 17 through the discharge passage 16 via the switching gate 15, and when forming a one-sided image, the recording sheet 7 is directly placed on the upper portion of the image forming apparatus main body 1 by the discharge roll 17. It is discharged onto a provided discharge tray 18.

  At that time, as shown in FIGS. 6 and 7, the switching gate 15 is pushed up by the leading end of the recording paper 7 discharged from the fixing device 12 and rotated to the second position in the clockwise direction in the drawing. When the sensor 31 is shielded by the operating arm portion 42 of the switching gate 15 to detect that the leading edge of the recording sheet 7 has reached the position of the switching gate 15 and the passage of the recording sheet 7 through the switching gate 15 is completed. As shown in FIG. 1, the switching gate 15 returns to the first position where the discharge passage 16 is closed.

  For this reason, when a jam, which is a jam of the recording paper 7, occurs in the discharge portion of the fixing device 12 on the front side of the switching gate 15, the switching gate 15 is not rotated clockwise in FIG. 7 is not detected, and the control circuit 23 detects that a jam has occurred.

  Further, when a jam occurs before the discharge roll 17 after the recording sheet 7 passes through the switching gate 15, the switching gate 15 remains rotated in the clockwise direction in FIG. Even after the passage of time passes through the switching gate 15, the sensor 31 does not detect the passage of the recording paper 7, but detects that a jam has occurred.

  Further, when images are formed on both sides of the recording paper 7, when the recording paper 7 having the image fixed on one side by the fixing device 12 is discharged by the discharge roll 17, as shown in FIG. When the rear end of the sheet 7 passes through the switching gate 15, the switching gate 15 rotates counterclockwise in the figure by its own weight and returns to the original first position. Then, the return of the switching gate 15 is detected by the sensor 31, and the discharge roll 17 is rotated in the reverse direction based on the detection signal from the sensor 31. Then, as shown in FIG. 9, the recording paper 7 is transported by a discharge roll 17 that is rotationally driven in the reverse direction, and the duplex transport path 19 is switched via a duplex transport path 19 that is switched by switching the switching gate 15. It is conveyed to 20.

  At that time, as shown in FIG. 10, the switching gate 15 is pushed by the leading end portion of the recording paper 7 whose operating arm portion 42 is transported to the double-side transport path 20, so that the second in the clockwise direction in the figure. The first position where the switching gate 15 closes the discharge passage 16 when the sensor 31 is shielded by the operating arm portion 42 of the switching gate 15 and the passage of the recording paper 7 through the switching gate 15 is completed. Return to.

  Therefore, when the recording paper 9 is transported to the double-sided transport path 20 via the double-sided transport path 19, if a jam that is a jam of the recording paper 7 occurs on the front side of the double-sided transport path 20, the switching gate 15 is not rotated clockwise in the figure, and the passage of the recording paper 7 is not detected by the sensor 31, and it is detected that a jam has occurred.

  Further, if a jam occurs in the middle of the double-sided conveyance path 20 after the recording paper 7 has passed through the double-sided conveyance path 19, the switching gate 15 remains rotated in the clockwise direction in FIG. Even when the time for which the recording paper 7 has passed through the switching gate 15 has elapsed, the passage of the recording paper 7 is not detected by the sensor 31 and it is detected that a jam has occurred.

  As described above, when a jam of the recording paper 7 is detected by the switching gate 15, a message to that effect is displayed on a control panel or the like (not shown), and the user opens the cover member 50 of the image forming apparatus. The sheet 7 is removed.

  Therefore, the combination of the switching gate 15 and the sensor 31 provided in the discharge unit of the fixing device 12 can detect a jam at the time of single-sided image formation on the recording paper 7 and can also detect a jam at the time of double-sided image formation on the recording paper 7. Can be detected, the configuration can be simplified, and the cost can be reduced.

  12: fixing device, 15: switching gate, 16: discharge conveyance path, 17: discharge roll, 19: double-side conveyance path, 31: sensor.

Claims (4)

A discharge conveying path between the fixing unit for fixing the image on the recording medium and the discharging unit for discharging the recording medium toward the outside;
A double-sided transport path through which the recording medium is transported by reversing the transport direction of the recording medium transported toward the outside during double-sided image formation;
It is rotatably disposed opposite to the discharge conveyance path, and protrudes into the discharge conveyance path when the recording medium is not conveyed, and is at a first position that opens the double-side conveyance path, When the recording medium is transported from the fixing unit, the recording medium is rotated by the recording medium toward the second position where the recording medium is retracted from the protruding position, and is transported to the duplex transport path when the double-sided image is formed. And a conveyance path switching member that rotates toward the second position,
Bei example and a detection means for detecting that the transport path switching member is rotated toward the second position,
The conveyance path switching member is disposed in the discharge conveyance path and rotated by the passage of the recording medium, and the operation arm section disposed in the double-side conveyance path and rotated by the passage of the recording medium. , And a part of the operating arm portion constitutes a light shielding plate for operating the detecting means . 2. The transport path switching device according to claim 1, wherein the transport path switching member is stopped or returned to the first position by the weight of the transport path switching member except when the recording medium is rotated. The operating arm portion of the transport path switching member is skewed or bent over the recording medium as the contact resistance with the recording medium varies along the direction intersecting the transport direction of the recording medium depending on the width of the recording medium. And a symmetrical arrangement with respect to a central portion along a direction intersecting with a conveyance direction of the recording medium. The conveyance path switching device according to 1 or 2. Image forming means for forming a toner image on one surface of the recording medium;
Fixing means for fixing a recording medium having a toner image formed on the one surface;
Discharging means for discharging the recording medium on which the toner image is fixed by the fixing means to the outside;
A discharge conveyance path between the fixing unit and the discharge unit, through which the recording medium is conveyed;
A double-sided transport path through which the recording medium is transported by reversing the transport direction of the recording medium transported toward the outside during double-sided image formation;
It is rotatably disposed opposite to the discharge conveyance path, and protrudes into the discharge conveyance path when the recording medium is not conveyed, and is at a first position that opens the double-side conveyance path, When the recording medium is transported from the fixing unit, the recording medium is rotated by the recording medium toward the second position where the recording medium is retracted from the protruding position, and is transported to the duplex transport path when the double-sided image is formed. And a conveyance path switching member that rotates toward the second position,
Detecting means for detecting that the transport path switching member is rotated toward the second position;
Bei to give a,
The conveyance path switching member is disposed in the discharge conveyance path and rotated by the passage of the recording medium, and the operation arm section disposed in the double-side conveyance path and rotated by the passage of the recording medium. And a part of the operating arm portion constitutes a light shielding plate for operating the detecting means .

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