JP6468249B2 - Recording medium conveying apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a conveyance device for a recording medium such as paper and an image forming apparatus including the recording medium conveyance device.

  In an image forming apparatus having a double-sided printing function such as a copying machine or a printer, the recording medium is transported at a discharge port for discharging the recording medium to change the front and back sides of the recording medium such as paper. Some include a recording medium conveyance device that switches directions. Examples of the image forming apparatus provided with such a recording medium conveying apparatus are disclosed in Patent Documents 1 to 3.

  The conventional image forming apparatuses described in Patent Documents 1 to 3 are, for example, forward and reverse directions with respect to a pair of discharge rollers disposed adjacent to a discharge port for discharging a sheet as a recording medium to the outside. Rotational force is transmitted to the. Then, the discharge roller pair is rotated forward so that a part of the sheet protrudes from the discharge port, and the discharge roller pair is reversed before the rear end of the sheet passes through the nip portion of the discharge roller pair. Switch. According to this configuration, the image forming apparatus can be downsized when the double-sided printing function is mounted on the image forming apparatus.

JP 2009-196766 A JP 2010-39116 A JP 2012-20845 A

  However, since the conventional recording medium conveyance devices described in Patent Documents 1 to 3 are rotated by positively applying a rotational force to the pair of discharge rollers arranged adjacent to the discharge port, the sheet is discharged. There has been a problem that the user's hair, clothes, and the like may be caught when being sent from the outlet to the inside.

  The present invention has been made in view of the above points, and when the recording medium discharge direction is switched using the recording medium discharge port, it is possible to prevent entrainment of hair, clothes, and the like at the discharge port. It is an object of the present invention to provide a recording medium conveying apparatus and an image forming apparatus that are improved in performance.

  In order to solve the above-described problems, the recording medium conveyance device of the present invention includes a conveyance path, a discharge port, a first conveyance roller pair, a second conveyance roller pair, and a power transmission mechanism. The conveyance path is provided for conveying the recording medium. The discharge port is formed at the end of the conveyance path and discharges the recording medium to the outside. The first conveying roller pair is disposed in the conveying path adjacent to the discharge port, and the rotational force is transmitted only in the first direction in which the recording medium is sent from the discharge port to the outside. The second transport roller pair is disposed in the transport path inside the first transport roller pair with respect to the discharge port, and the rotational force is transmitted to each of the first direction and the second direction for feeding the recording medium from the discharge port to the inside. The The power transmission mechanism has a common drive source that applies a rotational force to both the first transport roller pair and the second transport roller pair, and transmits the rotational force from the drive source. Then, the recording medium conveying device rotates the first conveying roller pair and the second conveying roller pair in the first direction so that the leading end of the recording medium protrudes from the discharge port, and the trailing end of the recording medium is the second conveying roller pair. After the recording medium is stopped before passing, the second conveyance roller pair is rotated in the second direction to switch the conveyance direction of the recording medium.

  According to the configuration of the present invention, the rotational force is not transmitted to the first transport roller pair disposed in the transport path adjacent to the discharge port in the second direction in which the recording medium is sent from the discharge port to the inside. That is, the first conveying roller pair does not generate a rotational force that may cause the hair or clothes to be caught at the discharge port. Therefore, it is possible to prevent the hair, clothes, and the like from being caught in the discharge port when the recording medium conveyance direction is switched using the discharge port of the recording medium.

1 is a cross-sectional view illustrating a schematic configuration of an image forming apparatus including a recording medium conveyance device (paper conveyance device) according to an embodiment of the present invention. 1 is an external perspective view of an image forming apparatus according to a first embodiment of the present invention. 1 is a perspective view of a paper transport device according to a first embodiment of the present invention. FIG. 3 is a cross-sectional view illustrating a transport path in a first direction of the sheet transport apparatus according to the first embodiment of the present invention. FIG. 3 is a cross-sectional view illustrating a transport path in a second direction of the paper transport apparatus according to the first embodiment of the present invention. It is a block diagram of the power transmission mechanism of the paper conveying apparatus which concerns on 1st Embodiment of this invention. It is a perspective view which shows the conveyance roller which comprises the 1st drive roller of the paper conveying apparatus which concerns on 1st Embodiment of this invention, a rotating shaft, and a power transmission member. FIG. 3 is a perspective view showing a gear and a power transmission member of the paper transport device according to the first embodiment of the present invention. It is a perspective view which shows the state which the gear and power transmission member of the paper conveying apparatus which concern on 1st Embodiment of this invention decomposed | disassembled.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the following contents.

  First, a schematic configuration of an image forming apparatus according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. 1 and 2 are an example of a cross-sectional view showing a schematic configuration of the image forming apparatus and an external perspective view of the image forming apparatus. The image forming apparatus 1 is a so-called printer that receives a command related to a print job from an external computer and executes printing. The image forming apparatus 1 receives signals relating to image data and job commands from a computer. The image forming apparatus 1 has a double-sided printing function that can automatically print images on both the front and back sides of the paper P that is a recording medium in one job.

  As shown in FIGS. 1 and 2, the image forming apparatus 1 includes a paper feed unit 2, a paper transport unit 3, an exposure unit 4, an image forming unit 10, a transfer unit 5, a fixing unit 6, and a paper discharge unit 7.

  The paper feed unit 2 stores a plurality of sheets P, and separates and feeds the sheets P one by one during printing. The paper transport unit 3 transports the paper P sent out from the paper feed unit 2 to the transfer unit 5 and the fixing unit 6, and further discharges the fixed paper P to the paper discharge unit 7 of the apparatus. The exposure unit 4 irradiates the image forming unit 10 with laser light L controlled based on the image data.

  As shown in FIG. 1, the image forming unit 10 is charged around the photosensitive drum 11 that is an image carrier that is rotatably supported in a predetermined direction (counterclockwise in FIG. 1) along the rotation direction. Unit 12, developing unit 13, and cleaning unit 14. The transfer unit 5 is disposed between the developing unit 13 and the cleaning unit 14.

  The charging unit 12 charges the surface of the photosensitive drum 11 to a predetermined potential by corona discharge, for example. Then, an electrostatic latent image of a document image is formed on the surface of the photosensitive drum 11 by the laser light L emitted from the exposure unit 4. The developing unit 13 develops a toner image by attaching toner to the electrostatic latent image. The toner supply to the developing unit 13 is performed from the toner container 8.

  The transfer unit 5 transfers the toner image on the surface of the photosensitive drum 11 onto the paper P. After the transfer, the cleaning unit 14 removes deposits such as toner remaining on the surface of the photosensitive drum 11. The fixing unit 6 heats and presses the paper P on which the toner image is transferred to fix the toner image on the paper P.

  The paper transport unit 3 includes a paper transport device 40 that is a recording medium transport device, a first transport path 31, a second transport path 32, and a branching section 33.

  The sheet conveying device 40 is arranged on the downstream side of the fixing unit 6 in the upper portion of the image forming apparatus 1 with respect to the sheet conveying direction when the sheet P is discharged to the sheet discharging unit 7. The paper transport device 40 includes a transport path 41 that is a part of the first transport path 31 and a discharge port 42 for discharging the paper P to the paper discharge unit 7.

  The first conveyance path 31 extends from the paper feeding unit 2 to the discharge port 42 of the paper conveyance device 40 through the transfer unit 5, the fixing unit 6, and the branching unit 33 in order. The branching unit 33 is provided between the fixing unit 6 and the sheet conveying device 40. The second conveyance path 32 branches from the first conveyance path 31 at the branching portion 33, passes below the fixing unit 6, below the transfer unit 5, and above the sheet feeding unit 2 in the sheet conveyance direction of the sheet feeding unit 2. It merges with the first transport path 31 on the downstream side. The branching section 33 is provided with a branching guide 33 a for switching the transporting direction of the paper P passing through the first transporting path 31 or the second transporting path 32.

  Next, the configuration of the sheet conveying device 40 will be described with reference to FIGS. 3 to 6 in addition to FIGS. 1 and 2. FIG. 3 is a perspective view of the sheet conveying device 40. 4 and 5 are cross-sectional views showing transport paths in the first direction and the second direction of the sheet transport apparatus 40. FIG. FIG. 6 is a configuration diagram of a power transmission mechanism of the sheet conveying device 40.

  The sheet conveying device 40 includes a first conveying roller pair 43, a second conveying roller pair 44, and a power transmission mechanism 50 shown in FIGS.

  The transport path 41 is a part of the first transport path 31 as described above, and is installed to transport the paper P. The conveyance path 41 extends from the lower surface of the paper conveyance device 40 whose outline is drawn with a two-dot chain line in FIGS. 4 and 5 to the upper left side surface. A discharge port 42 is formed at the end of the conveyance path 41 located on the upper left side of the sheet conveyance device 40 in FIGS. 4 and 5 and faces the sheet discharge unit 7.

  The first transport roller pair 43 is disposed in the transport path 41 adjacent to the discharge port 42. The first transport roller pair 43 includes a first drive roller 431 and a first driven roller 432. The first conveying roller pair 43 receives a rotational force from the power transmission mechanism 50 and feeds the sheet P entering the nip portion along the conveying path 41.

  The second transport roller pair 44 is a transport path 41 on the inner side of the first transport roller pair 43, and is more paper than the first transport roller pair 43 when transporting the paper P with the transport path 41 facing the discharge port 42. Arranged upstream in the transport direction. That is, the second transport roller pair 44 is closer to the branch portion 33 than the first transport roller pair 43. The second transport roller pair 44 includes a second drive roller 441 and a second driven roller 442. The second conveying roller pair 44 receives a rotational force from the power transmission mechanism 50 and feeds the sheet P entering the nip portion along the conveying path 41.

  The power transmission mechanism 50 is disposed on either the front side or the back side of the conveyance path 41 in the depth direction of the paper surface in FIGS. 4 and 5. The power transmission mechanism 50 includes a motor 51, which is a drive source shown in FIG. The motor 51 is a common drive source that applies a rotational force to both the first transport roller pair 43 and the second transport roller pair 44. In addition, about this drive source, it may replace with the motor 51 and may decide to obtain motive power from the motor provided in the other location. The gear group 52 includes a plurality of gears that mesh with each other, and transmits the rotational force from the motor 51 to both the first transport roller pair 43 and the second transport roller pair 44.

  Here, the conveyance path and the conveyance direction of the paper P in the case of conveying the paper P toward the discharge port 42 through the first conveyance path 31, that is, the conveyance path 41, are shown as a broken line arrow C1 in FIG. The direction in which the paper P indicated by the dashed arrow C1 is sent to the outside from the discharge port 42 is referred to as a first direction. The rotation directions in the first direction of the first transport roller pair 43 and the second transport roller pair 44 are indicated by white arrows in FIGS. 4 and 6.

  Further, the conveyance path and the conveyance direction of the paper P in the case of conveying the paper P from the discharge port 42 through the branching portion 33 to the second conveyance path 32 through the conveyance path 41 are shown as a dashed arrow C2 in FIG. The direction in which the paper P indicated by the dashed arrow C2 is sent from the discharge port 42 to the inside is referred to as a second direction. The rotation direction of the second direction of the second transport roller pair 44 is indicated by a white arrow in FIG. As will be described later, the rotational force is not transmitted to the first transport roller pair 43 in the second direction.

  When printing on both the front and back sides of the paper P, the paper transport device 40 switches the transport direction of the paper P at the location of the discharge port 42 in order to change the front and back surfaces on which the image of the paper P is formed. Specifically, the sheet conveying device 40 projects the leading end of the sheet P that has entered the conveying path 41 in the first direction through the branching portion 33 to the outside from the discharge port 42, and the trailing end of the sheet P is the second conveying roller. After stopping the paper P before passing through the pair 44, the transport direction of the paper P is switched and the paper P is sent toward the branching portion 33 in the second direction.

  Next, a more detailed configuration of the sheet conveying device 40 will be described with reference to FIGS. FIG. 7 is a perspective view showing a transport roller, a rotating shaft, and a power transmission member that constitute the first drive roller 431 of the paper transport apparatus 40. 8 and 9 are a perspective view showing a gear and a power transmission member of the paper transport device 40 and a perspective view showing a state in which they are disassembled.

  The first drive roller 431 of the first transport roller pair 43 includes a transport roller 431a and a rotation shaft 431b shown in FIG. The transport rollers 431a are arranged at two locations side by side in the paper width direction intersecting the paper transport direction. The rotation shaft 431b extends in the paper width direction and penetrates the center of the axis of the transport roller 431a. The transport roller 431a is fixed to the rotation shaft 431b and rotates around the axis of the rotation shaft 431b to transport the paper P.

  A gear 52A of the power transmission mechanism 50 and a power transmission member 53 are provided at one end of the rotation shaft 431b in the axial direction.

  The power transmission member 53 has a cylindrical outer shape, is fixed to the outer periphery of the rotation shaft 431b, and directly supports the rotation shaft 431b. The power transmission member 53 is, for example, a one-way clutch, and transmits the rotational force only in the first direction in which the paper P is sent to the outside from the discharge port 42 to the transport roller 431a.

  More specifically, for example, a one-way clutch has an outer ring, an inner ring, a roller, and a spring. The inner ring supports the rotation shaft 431b. A pocket that can accommodate a roller connected to one end of the spring is provided on the inner peripheral surface of the outer ring. The pocket may be provided on the outer peripheral surface of the inner ring. The roller is held by a spring so as to contact the pocket of the outer ring and the outer peripheral surface of the inner ring, and can move slightly in the circumferential direction inside the pocket.

  When the outer ring tries to rotate in the first direction with respect to the inner ring, the contact pressure of the roller sandwiched between the pocket and the outer peripheral surface of the inner ring increases with the outer peripheral surface of the inner ring, and the inner ring becomes integral with the outer ring. To rotate and transmit power. On the other hand, when the outer ring tries to rotate in the second direction with respect to the inner ring, the roller escapes to the inside of the pocket, the contact pressure with the outer peripheral surface of the inner ring is lowered, and no power is transmitted due to the inner ring sliding against the outer ring. .

  That is, the power transmission mechanism 50 includes a power transmission member 53 that transmits a rotational force only in the first direction to the power transmission path for the first transport roller pair 43.

  The gear 52 </ b> A is one of a plurality of gears constituting the gear group 52, and transmits a rotational force from the motor 51 to the first transport roller pair 43. As shown in FIGS. 8 and 9, the gear 52 </ b> A includes a recess 54 around the rotation axis. The recess 54 is formed in a shape and size that can accommodate the power transmission member 53.

  The power transmission member 53 includes an engagement portion 53a that is recessed radially inward on the outer peripheral surface. The recess 54 includes a protrusion 54a that protrudes radially inward on the inner peripheral surface. The power transmission member 53 is inserted into the recess 54 along the axial direction. At this time, the protrusion 54a enters and engages with the engaging portion 53a, so that the gear 52A holds the outer peripheral portion of the power transmission member 53 in a non-rotatable manner.

  As described above, according to the configuration of the embodiment of the present invention, the second direction in which the paper P is sent from the discharge port 42 to the first conveyance roller pair 43 disposed in the conveyance path 41 adjacent to the discharge port 42. Rotational force is not transmitted to That is, the first conveying roller pair 43 does not have a rotational force that may cause the hair or clothes to be caught in the discharge port 42. Therefore, when the transport direction of the paper P is switched using the discharge port 42, it is possible to prevent the hair, clothes, and the like from being caught in the discharge port 42. Therefore, it is possible to provide the sheet conveying apparatus 40 and the image forming apparatus 1 that are improved in safety.

  And since the power transmission mechanism 50 is provided with the power transmission member 53 which transmits rotational force only to a 1st direction in the power transmission path | route with respect to the 1st conveyance roller pair 43, the structure which prevents entrapment of hair, clothes, etc. in the discharge port 42 Can be easily obtained. The power transmission member 53 may be provided for any gear in the gear group 52 from the motor 51 to the first transport roller pair 43.

  And since the power transmission member 53 supports the rotating shaft 431b of the first transport roller pair 43, it is possible to prevent the rotational force from being transmitted in the second direction only to the first transport roller pair 43. Thereby, it is possible to rotate another rotating member using the gear group 52 as needed.

  Furthermore, since the power transmission member 53 is a one-way clutch, it becomes possible to prevent the hair, clothes, and the like from being caught in the discharge port 42 with a simple configuration. The power transmission member 53 is not limited to the one-way clutch, and may be another functional member as long as the rotational force can be transmitted in only one direction. For example, an electromagnetic clutch or the like can be applied.

  Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the invention.

  The present invention can be used in a recording medium conveyance device and an image forming apparatus including the recording medium conveyance device.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 3 Paper conveyance part 31 1st conveyance path 32 2nd conveyance path 33 Branching part 40 Paper conveyance apparatus (recording medium conveyance apparatus)
41 transport path 42 discharge port 43 first transport roller pair 44 second transport roller pair 50 power transmission mechanism 51 motor (drive source)
52 Gear group 53 Power transmission member P Paper (recording medium)

Claims (5)

A transport path for transporting the recording medium;
A discharge port that is formed at an end of the conveyance path and discharges the recording medium to the outside;
A first transport roller pair disposed in the transport path adjacent to the discharge port and having a rotational force transmitted only in a first direction in which a recording medium is sent to the outside from the discharge port;
Rotational force is transmitted in each of the first direction and the second direction in which the recording medium is sent from the discharge port to the inside by being arranged in the transfer path inside the first transfer roller pair with respect to the discharge port. A second transport roller pair;
A power transmission mechanism having a common drive source for applying a rotational force to both the first transport roller pair and the second transport roller pair and transmitting the rotational force from the drive source;
With
The first conveying roller pair and the second conveying roller pair are rotated in the first direction so that the leading edge of the recording medium protrudes from the discharge port, and the trailing edge of the recording medium passes through the second conveying roller pair. A recording medium conveying apparatus, wherein the recording medium is stopped before the recording medium is stopped, and then the second conveying roller pair is rotated in the second direction to switch the conveying direction of the recording medium.   The recording medium transport apparatus according to claim 1, wherein the power transmission mechanism includes a power transmission member that transmits a rotational force only in the first direction to a power transmission path with respect to the first transport roller pair.   The recording medium conveyance device according to claim 2, wherein the power transmission member supports a rotation shaft of the first conveyance roller pair.   The recording medium conveying apparatus according to claim 2, wherein the power transmission member is a one-way clutch.   An image forming apparatus comprising the recording medium conveyance device according to claim 1.

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