JP2005255413A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily expose a paper carrying passage when extracting a paper carrying unit, while suitably holding nip pressure of carrier roller pairs when carrying paper. <P>SOLUTION: The paper carrying unit 30 can be extracted from a body 2 of an image forming device 1, and has a base part 40 and a paper guide member 50. The paper guide member 50 rotates around a rotary shaft 51, and opens and closes to the base member 40. The paper carrying passage 60 is exposed by opening the paper guide member 50. When inserting the paper carrying unit 30 into the body 2 in a state of closing the paper guide member 50, the paper guide member 50 is supported by contacting with a support surface 2b arranged in the body 2 via a pressure generating member 80 arranged in an upper part of the paper guide member 50, and the carrier roller pairs 61 of the paper carrying passage 60 form a carrying nip by being brought into pressure contact under predetermined pressure. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus represented by a copying machine, a printer, and the like.

  An image forming apparatus such as a copying machine or a printer has a paper feeding unit that stacks and stores paper, an image forming unit that forms a toner image, a transfer unit that transfers a toner image on the paper, and an unfixed toner image fixed on the paper. A fixing unit is provided. These image forming apparatuses generally have a configuration in which a paper feeding unit is arranged in the lower part and an image forming unit, a transfer unit, and a fixing unit are arranged in the upper part. When the distance between these components is large, a paper transport unit including a paper guide member and a transport roller is provided to deliver the paper.

  When a paper jam occurs in the image forming apparatus, it is necessary to remove the paper that caused the jam. Conventionally, various types of jam processing have been proposed. For example, an image forming apparatus includes a unit that can be pulled out from the main body, and by pulling out the unit, the sheet conveyance path can be exposed and the sheet can be removed. There is something. An example of an image forming apparatus provided with such a pullable unit can be seen in Japanese Patent Application Laid-Open No. H10-228707.

The image forming apparatus described in Patent Document 1 includes a conveyance path unit that can be pulled out in the horizontal direction from the front of the image forming apparatus. In order to perform paper jam processing, with the transport path unit pulled out, the lower transport section is opened downward to expose the paper transport path. The lower transport section closed after the jam processing is finished is prevented from being detached from the transport path unit by a magnet or a latch mechanism.
Japanese Unexamined Patent Publication No. 2003-241454 (5th page, FIG. 2 to FIG. 3)

  However, as described in Patent Document 1, when a magnet is used to close the lower conveyance unit, the product cost increases. In addition, if the magnetic force of the magnet becomes weak due to aging, etc. due to long-term use, the nip pressure between the rollers provided in each of the transport path unit and the lower transport section will decrease, and it may cause trouble in paper transport There is sex. This further increases the frequency of paper jams. On the other hand, if the magnetic force of the magnet is too strong, a large force is required to open the lower transport section, so the operability is bad, and the lower transport section is damaged or the user is injured by the impact force when the magnet is separated. There is a risk that. A fixing mechanism such as a latch mechanism is inconvenient to remove and is not easy to use.

  The present invention has been made in view of the above points. With a simple configuration without using a functional member such as a magnet, the nip pressure of the pair of transport rollers can be suitably maintained during sheet transport, and the sheet transport unit can be It is an object of the present invention to provide an image forming apparatus that can easily expose a sheet conveyance path when being pulled out.

  In order to solve the above-described problems, the present invention provides a base portion that constitutes one surface of a paper conveyance path and a paper sheet that can be opened and closed with respect to the base portion to expose the paper conveyance path. Image forming provided with a paper transport unit provided with a guide member and a pair of transport rollers for transporting paper while sandwiching the paper by rollers provided on each of the base portion and the paper guide member. In the apparatus, when the paper transport unit is inserted into the main body with the paper guide member closed, the paper guide member is interposed on the support surface provided on the outer side in the opening direction of the paper guide member via the pressure generating member. Thus, the conveying roller pair is brought into pressure contact with a predetermined pressure to form a conveying nip.

  Further, the base portion includes a movement restricting surface for restricting the movement of the paper guide member when the paper guide member is closed.

  Further, the pressure generating member is provided with a rolling member at the tip thereof.

  Further, the pressure generating member is supported by the paper guide member through an elastic member.

  Further, any one of the rollers constituting the pair of transport rollers is supported via an elastic member, and the elastic force of the elastic member is interposed between the pressure generating member and the paper guide member. It was decided that it was smaller than the elastic force of the member.

  Further, at least one of the support surface and the contact surface of the pressure generating member with the support surface is made of an elastic member.

  The paper guide member is in contact with the support surface at a plurality of locations.

  According to the configuration of the present invention, when the paper transport unit is inserted into the image forming apparatus main body with the paper guide member closed, the paper guide member is placed on the support surface provided on the outer side in the opening direction of the paper guide member. By supporting and supporting through the pressure generating member, the pair of transport rollers is pressed against each other with a predetermined pressure to form a transport nip. The nip pressure of the conveying roller pair can be suitably maintained. Further, when the paper guide member is opened or closed with respect to the base portion, it is not necessary to separate the magnet portion or attach / detach the latch portion, so that the operation is very simple.

  In addition, since the base portion is provided with a movement restricting surface that restricts the movement of the paper guide member when the paper guide member is closed, the paper guide member approaches the base portion by the action of the pressure generating member. Even so, the distance between the paper guide member and the base portion can be made constant. As a result, the paper guide member can be held at a predetermined paper guide position. Further, the nip pressure does not become too high. Therefore, since the paper transport path provided in the paper transport unit is correctly configured, it is possible to prevent paper transport failure and paper jam. As a result, a highly reliable image forming apparatus can be provided.

  Further, since the pressure generating member is provided with a rolling member at the tip thereof, the paper transport unit can be smoothly inserted when the paper transport unit is inserted into the main body of the image forming apparatus. In addition, significant wear does not occur at the portion where the support surface and the pressure generating member are in contact with each other. Therefore, it is possible to reduce the frequency of replacement of the parts of these contact portions, and to reduce the running cost. Further, since dust due to wear does not occur, the paper passing through the paper transport unit can be managed cleanly.

  In addition, since the pressure generating member is supported by the paper guide member via the elastic member, the image forming apparatus main body and the paper transport unit are rattled due to secular change due to long-term use of the image forming apparatus. Even when the above occurs, the nip pressure of the pair of conveying rollers can be maintained in a suitable state, and the insertion of the sheet conveying unit into the main body does not become tight. Therefore, it is possible to always obtain a good paper conveyance performance and to smoothly insert the paper conveyance unit.

  Also, one of the rollers constituting the conveying roller pair is supported via an elastic member, and the elastic force of the elastic member causes the elastic member elastically interposed between the pressure generating member and the paper guide member. Since the force is smaller than the force, it is possible to prevent the sheet guide member from being moved in the opening direction by the action of the elastic member that supports the roller. As a result, it is possible to enhance the effect of keeping the distance between the paper guide member and the base portion constant.

  In addition, since at least one of the support surface and the contact surface of the pressure generating member with the support surface is made of an elastic member, insertion into the main body of the paper transport unit is tight. In addition to preventing the friction, it is possible to further reduce the friction generated between the support surface and the pressure generating member. Therefore, it is possible to provide a high-performance image forming apparatus that can smoothly insert the paper transport unit indefinitely and can cleanly manage the paper passing therethrough.

  Further, since the paper guide member is in contact with the support surface at a plurality of locations, the main body and other components can support the paper guide member at a plurality of locations. As a result, the paper guide member does not tilt and can be stabilized at a predetermined paper guide position. Thereby, it is possible to further improve the sheet conveyance performance.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  First, the image output operation of the image forming apparatus of the present invention will be described while explaining the outline of the structure with reference to FIG. FIG. 1 is a schematic vertical sectional front view showing an image forming apparatus according to an embodiment of the present invention. A solid line arrow in the drawing indicates a sheet conveyance path and a conveyance direction.

  As shown in FIG. 1, a cassette type paper feeding unit 20 is disposed at the lower part of the main body 2 of the image forming apparatus 1. The cassette type paper supply unit 20 is provided with a general general-purpose paper cassette 21 and a large capacity paper cassette 22. Two large-capacity paper cassettes 22 having the same capacity are arranged in the horizontal direction at the same height, and constitute an upstream large-capacity paper cassette 22A and a downstream large-capacity paper cassette 22B. In these paper cassettes, paper P such as cut paper before printing is stacked and stored, and the paper P is separated and sent out one by one.

  A manual paper feed unit 3 is provided outside the upper right side of the main body 2. On the manual sheet feeding unit 3, paper P having a size not included in the cassette type sheet feeding unit 20 or a sheet to be fed one by one such as an OHP sheet is placed.

  The image forming apparatus 1 includes a paper transport unit 4 therein. The sheet transport unit 4 is positioned to the right of the paper feed direction in terms of the cassette type paper feed unit 20, and is positioned to the left of the manual feed unit 3. The paper P sent out from the cassette type paper feeding unit 20 is conveyed vertically upward along the side surface of the main body 2 by the paper conveying unit 4, and the paper P sent out from the manual paper feeding unit 3 is conveyed horizontally leftward. Of the two large-capacity paper cassettes 22, the paper P sent out from the left upstream large-capacity paper cassette 22A is sent to the right through the horizontal paper transport path above the right downstream large-capacity paper cassette 22B. After that, it is conveyed vertically upward along the side surface of the main body 2. The horizontal paper conveyance path and its peripheral components are unitized as a paper conveyance unit 30 and can be drawn forward from the main body 2. Details of the paper transport unit 30 will be described later.

  A registration roller 5 is provided at the downstream end in the sheet conveyance direction of the sheet conveyance unit 4 and immediately upstream of the transfer unit 9. The registration roller 5 feeds the paper P toward the transfer unit 9 in synchronization with a toner image formed by the image forming unit 8 described later while correcting the oblique feeding of the paper P.

  A document feeding unit 6 is provided on the upper surface of the main body 2 of the image forming apparatus 1, and an optical unit 7 is provided below the document feeding unit 6. When a user copies a document, a document on which an image such as a character, a figure, or a pattern is drawn is stacked on the document feeding unit 6. The document feeding unit 6 separates the documents one by one and feeds the document, and the optical unit 7 reads the image data.

  An image forming unit 8 and a transfer unit 9 are provided on the downstream side of the registration roller 5 in the sheet conveyance direction and below the optical unit 7. In the image forming unit 8, an electrostatic latent image of the document image is created based on the image data read by the optical unit 7. A toner image is formed from the electrostatic latent image, and the toner image is transferred by the transfer unit 9 to the pre-printing paper P sent in synchronization by the registration roller 5.

  A fixing unit 10 is provided on the downstream side of the transfer unit 9. The sheet P carrying the unfixed toner image in the transfer unit 9 is sent to the fixing unit 10 and the toner image is fixed by the heat roller.

  A discharge / branch unit 11 is provided on the downstream side of the fixing unit 10 and in the vicinity of the left side surface of the main body 2. The sheet P discharged from the fixing unit 10 is discharged from the discharge / branch unit 11 to a sheet receiving tray outside the apparatus when duplex printing is not performed.

  A duplex printing unit 12 is provided below the portion from the image forming unit 8 to the discharge / branch unit 11 and above the cassette type paper feeding unit 20. When performing double-sided printing, the paper P discharged from the fixing unit 10 is sent to the double-sided printing unit 12 through the discharge / branch unit 11. The paper P sent to the duplex printing unit 12 is subsequently switched in the feeding direction, and sent again to the transfer unit 9 via the paper transport unit 4 and the registration roller 5.

  Next, a detailed configuration of the paper transport unit 30 of the image forming apparatus 1 according to the first embodiment of the present disclosure will be described with reference to FIGS.

  2 is a perspective view of the paper transport unit, FIG. 3 is a schematic vertical sectional front view showing a schematic configuration of the paper transport unit and its periphery, FIG. 4 is a top view of the same model horizontal cross section, and FIG. 5 is a model of the paper transport unit. FIG. 2 is a front view of a vertical cross section showing a state in which the paper guide member is opened. FIG. 6 is a schematic partial enlarged vertical sectional right side view of the paper transport unit, and FIG. 7 is a vertical sectional right side view showing the pressure generating member. 2 to 4, the dashed arrows in the drawings indicate the conveyance path and conveyance direction of the paper P, and the solid white arrows indicate the drawing direction of the paper conveyance unit 30.

  As shown in FIG. 2, the main part of the paper transport unit 30 includes a base portion 40 and a paper guide member 50. A guide roller 41 is rotatably provided below the base portion 40. The guide roller 41 can be engaged with a rail (not shown) inside the main body 2 of the image forming apparatus 1, and the paper transport unit 30 can be slid horizontally in the direction of arrow Z shown in FIG.

  As shown in FIG. 3, the paper transport unit 30 is disposed above the downstream large-capacity paper cassette 22B. A frame 2 a that is an internal structural member of the main body 2 of the image forming apparatus 1 is provided immediately above the paper transport unit 30.

  The base unit 40 corresponds to a main body provided at the lower part of the paper transport unit 30. Between the base portion 40 and the paper guide member 50, a paper transport path 60 for transporting the paper P to the right in the horizontal direction is provided. The base section 40 constitutes one surface below the paper transport path 60. The base portion 40 is shaped and arranged so as to cover the downstream large-capacity paper cassette 22B.

  As shown in FIGS. 2 and 6, a movement restricting surface 42 that restricts the movement of the paper guide member 50 is provided in the vicinity of the paper guide member 50 above the base portion 40. The movement restricting surface 42 is provided in two places, one at a position corresponding to the front side of the paper guide member 50 and the outside of the side face on the back side in the paper width direction perpendicular to the paper transport direction.

  An upstream sheet feeding device 70A is provided in the upstream portion of the base portion 40, and a downstream sheet feeding device 70B is provided in the downstream portion. The upstream-side paper feeding device 70 </ b> A sends the paper P stored in the upstream large-capacity paper cassette 22 </ b> A to the paper transport path 60. The downstream-side paper feeding device 70B sends out the paper P stacked and accommodated in the downstream large-capacity paper cassette 22B to a vertical paper conveyance path (see FIG. 1) of the paper conveyance unit 4. Since the upstream sheet feeding device 70A and the downstream sheet feeding device 70B have almost the same configuration, the names “upstream” and “downstream”, and “A”, “ The symbol “B” is omitted. Similarly, the upstream large-capacity paper cassette 22A and the downstream large-capacity paper cassette 22B are named “upstream” and “downstream”, and “A” and “B” unless otherwise required. The sign of is omitted.

  The paper feed device 70 includes a forward feed roller 71, a paper feed roller 72, and a separation roller 73. As shown in FIG. 4, the forward feed roller 71 and the paper feed roller 72 are connected to each other through driven gears 71 a and 72 a via an intermediate gear 74. The paper feed roller 72 is connected to the motor 75 via a driven gear 72b and a drive gear 75a. Therefore, when the paper feed roller 72 is rotated by the motor 75, the forward feed roller 71 is also rotated in the same direction as the paper feed roller 72. From the lower side of the forward feed roller 71, the paper P stacked on the large-capacity paper cassette 22 is pushed up by an elevating mechanism (not shown), and one of the uppermost layers of the paper P abuts. Then, the paper P is delivered to the paper feed roller 72 by the forward feed roller 71, and sent by the paper feed roller 72 to the paper transport path 60 or the vertical paper transport path (see FIG. 1) of the paper transport unit 4. .

  The separation roller 73 is connected to the paper feed roller 72 through driven gears 73a and 72a. Therefore, when the paper feed roller 72 is rotated by the motor 75, the separation roller 73 is rotated in the direction opposite to the paper feed roller 72. A torque limiter (not shown) is provided between the separation roller 73 and the driven gear 73a. When the sheet P does not exist in the nip formed by the separation roller 73 coming into contact with the sheet feeding roller 72 or when only one sheet P enters, the separation roller 73 is subjected to a torque greater than the torque set by the torque limiter. The separation roller 73 rotates in the direction of carrying out the paper P according to the paper feed roller 72. However, when a plurality of sheets of paper P enter the nip and enter the nip, the torque applied to the separation roller 73 does not exceed the torque limiter set torque, and the lower stacked paper P is returned to the large capacity paper cassette 22. Rotate to. This prevents the problem of double feeding in which the sheets P are fed in an overlapping manner.

  Of the rollers, gears, and motors described above, the motor 75 and the drive gear 75 a are provided in the main body 2, and the others are all provided in the paper transport unit 30. Therefore, after the paper transport unit 30 is pulled out from the main body 2, the connection between the drive gear 75a and the driven gear 72b is released.

  As shown in FIGS. 2 and 3, the paper guide member 50 is provided on the upper portion of the paper transport unit 30. The sheet guide member 50 constitutes one surface on the upper side of the sheet conveyance path 60. The paper guide member 50 is supported on the base portion 40 by a rotating shaft 51 provided at the upstream end thereof. As shown in FIG. 5, the paper guide member 50 is rotatable in a vertical plane perpendicular to the paper width direction with the rotation shaft 51 as the center and the downstream end as a free end. By opening the paper guide member 50 with respect to the base portion 40, the paper transport path 60 can be exposed.

  As shown in FIGS. 2 and 6, two engaging projections 52 are provided on the front and rear side surfaces of the paper guide member 50, one in each. These two engagement protrusions 52 are respectively provided at positions corresponding to the two movement restricting surfaces 42 provided on the base portion 40. The engaging protrusion 52 protrudes horizontally toward the outside of the paper guide member 50. When the paper guide member 50 is closed, the engaging protrusion 52 comes into contact with the movement restricting surface 42 so that the paper guide member 50 cannot move downward more than necessary.

  As illustrated in FIGS. 3 and 6, the sheet conveyance path 60 is provided between the base portion 40 and the sheet guide member 50. In the sheet conveyance path 60, the engagement protrusion 52 of the sheet guide member 50 abuts on the movement restriction surface 42 of the base unit 40, and the downward movement of the sheet guide member 50 is regulated, whereby the base unit 40 and the sheet guide are arranged. It is formed between the members 50.

  A conveyance roller pair 61 is provided in the paper conveyance path 60. Two conveyance roller pairs 61 are provided along the paper conveyance direction. The conveyance roller pair 61 includes a conveyance roller 61 a provided in the base portion 40 and a pinch roller 61 b provided in the paper guide member 50. The pinch roller 61 b is urged downward by a spring 62 that is an elastic member provided on the paper guide member 50. However, the pinch roller 61b does not come off the paper guide member 50 due to the action of a stopper (not shown). The paper P transported through the paper transport path 60 is inserted into a transport nip formed by bringing the transport roller 61a and the pinch roller 61b into pressure contact with each other with a predetermined pressure.

  As shown in FIG. 5, when the paper guide member 50 is opened, the transport roller 61a and the pinch roller 61b are separated from each other and the paper transport path 60 is exposed. As a result, when a paper jam occurs in the paper transport path 60, the staying paper P can be easily taken out.

  As shown in FIG. 4, the transport roller 61a is connected to the motor 75B via a driven gear 63, an intermediate gear 64, and a drive gear 75Ba. Thereby, the conveyance roller 61a is rotated by the motor 75B. Two transport rollers 61a provided along the paper transport direction are connected by a belt 65 and rotate in the same direction. The pinch roller 61b rotates in accordance with the rotation of the transport roller 61a by contacting the transport roller 61a. Similarly to the above, after the paper transport unit 30 is pulled out from the main body 2, the connection between the drive gear 75Ba and the intermediate gear 64 is released.

  As shown in FIGS. 2 and 3, a pressure generating member 80 is provided on the upper portion of the upstream portion of the paper guide member 50. As shown in FIGS. 2 and 6, the pressure generating member 80 is provided at two locations in the paper width direction.

  As shown in FIG. 7, the pressure generating member 80 is supported by the paper guide member 50 via a spring 81 that is an elastic member. The spring 81 urges the pressure generating member 80 upward, and is composed of a compression coil spring. However, the engaging portion 80 a provided at the lower end of the pressure generating member 80 does not jump out upward by being engaged with the frame 53 of the paper guide member 50. The pressure generating member 80 has a hemispherical upper portion and is made of polyacetal (POM).

  Note that the elastic force of all the springs 62 interposed between the pinch roller 61b and the paper guide member 50 is more than the elastic force of all the springs 81 interposed between the pressure generating member 80 and the paper guide member 50. Is also small.

  As described above with reference to FIG. 3, a frame 2 a that is an internal structural member of the main body 2 of the image forming apparatus 1 is provided immediately above the paper transport unit 30, that is, outside the paper guide member 50 in the opening direction. A support surface 2b is provided at a position corresponding to the pressure generating member 80 on the bottom surface of the frame 2a. When the paper transport unit 30 is inserted into the main body 2, the pressure generating member 80 comes into contact with the support surface 2b. As a result, the paper guide member 50 is supported on the support surface 2b of the main body 2 via the pressure generating member 80, and the conveying roller pair 61 is brought into pressure contact with a predetermined pressure to form a conveying nip.

  In this way, when the paper transport unit 30 is inserted into the main body 2 of the image forming apparatus 1 with the paper guide member 50 closed, the main body 2 is located outside the paper guide member 50 in the opening direction. Since the conveying roller pair 61 is pressed against the supporting surface 2b provided on the support surface 2b via a pressure generating member 80 at a predetermined pressure to form a conveying nip, the sheet conveying unit 30 is mounted on the main body. It is possible to suitably hold the nip pressure of the conveying roller pair 61 during the conveyance of the sheet only by inserting the sheet 2. Further, when the paper guide member 50 is opened or closed with respect to the base portion 40, the operation of pulling away the magnet portion or attaching / detaching the latch portion is not required, so that the operation is very simple.

  Further, since the base portion 40 includes a movement restricting surface 42 that restricts the movement of the paper guide member 50 when the paper guide member 50 is closed, the paper guide member 50 is brought into the base by the action of the pressure generating member 80. Even when approaching the portion 40, the distance between the paper guide member 50 and the base portion 40 can be made constant. As a result, the paper guide member 50 can be held at a predetermined paper guide position. Further, the nip pressure does not become too high. Accordingly, since the paper transport path 60 provided in the paper transport unit 30 is correctly configured, it is possible to prevent the paper P from being poorly transported and paper jamming. As a result, a highly reliable image forming apparatus 1 can be provided.

  In addition, since the pressure generating member 80 is supported by the paper guide member 50 via the spring 81 that is an elastic member, the main body 2 of the image forming apparatus 1 and the like are changed due to secular change due to long-time use of the image forming apparatus 1. Even when the paper transport unit 30 is rattling or the like, the nip pressure of the transport roller pair 61 can be maintained in a suitable state, and the insertion of the paper transport unit 30 into the main body 2 can be tight. Absent. Therefore, it is possible to always obtain a good sheet conveyance performance and to smoothly insert the sheet conveyance unit 30.

  Of the rollers constituting the conveying roller pair 61, the pinch roller 61 b is supported via a spring 62 that is an elastic member, and the elastic force of the spring 62 is between the pressure generating member 80 and the paper guide member 50. Therefore, the paper guide member 50 can be prevented from being moved in the opening direction by the action of the spring 62 that supports the pinch roller 61b. As a result, it is possible to enhance the effect of keeping the distance between the paper guide member 50 and the base portion 40 constant.

  Further, since the paper guide member 50 comes into contact with the support surface 2b of the main body 2 by the pressure generating members 80 provided at two places, the main body 2 can support the paper guide member 50 at a plurality of places. As a result, the paper guide member 50 does not tilt and can be stabilized at a predetermined paper guide position. Thereby, it is possible to further improve the conveyance performance of the paper P.

  The main body 2 of the image forming apparatus 1 is provided with a plurality of support surfaces 2b, and the sheet guide member 50 comes into contact with the support surface 2b via a pressure generating member 80 provided at a position corresponding to each of the support surfaces 2b. It is good as being supported. The member having the support surface may be another member instead of the frame 2a of the main body 2.

  Next, a detailed configuration of the paper transport unit 30 of the image forming apparatus 1 according to the second embodiment of the present invention will be described with reference to FIG. FIG. 8 is a right side view of the vertical section showing the pressure generating member. Note that the basic configuration of this embodiment is the same as that of the first embodiment described with reference to FIGS. 2 to 7, so the components common to the first embodiment are described in the drawings and The explanation will be omitted.

  The second embodiment is different from the first embodiment in a pressure generating member 80 shown in FIG. The pressure generating member 80 has a guide roller 82 as a rolling member rotatably provided at the upper end. The guide roller 82 is made of an elastic material such as synthetic rubber or elastomer. The pressure generating member 80 is supported by the paper guide member 50 via a spring 81 that is an elastic member. When the paper transport unit 30 is inserted into the main body 2, the guide roller 82 comes into contact with the support surface 2 b of the main body 2 and rotates.

  Thus, since the pressure generating member 80 includes the guide roller 82 that is a rolling member at the tip thereof, the insertion of the paper transport unit 30 is smoothly performed when the paper transport unit 30 is inserted into the main body 2 of the image forming apparatus 1. Can be performed. In addition, no significant wear occurs at the portion where the support surface 2b of the main body 2 and the pressure generating member 80 are in contact with each other. Therefore, it is possible to reduce the frequency of replacement of the parts of these contact portions, and to reduce the running cost. Further, since dust due to wear does not occur, the paper P passing through the paper transport unit 30 can be managed cleanly.

  Further, of the contact surface 2b of the main body 2 and the contact surface of the pressure generating member 80 with the support surface 2b, the contact surface of the pressure generating member 80 is formed of an elastic member. Can be prevented from being cramped, and the friction generated between the support surface 2b and the pressure generating member 80 can be further reduced. Therefore, it is possible to provide the high-performance image forming apparatus 1 that can smoothly insert the paper transport unit 30 indefinitely and can cleanly manage the paper P that passes through the paper transport unit 30. On the other hand, even if the support surface 2b is made of an elastic member, similar actions and effects can be obtained.

  Next, the detailed configuration of the image forming apparatus 1 according to the third embodiment of the present invention will be described with reference to FIGS. 9 to 13 in addition to FIG. FIG. 9 is a partial front view showing the periphery of the duplex printing unit of the image forming apparatus, and FIG. 10 is a schematic partial enlarged front view showing a part of FIG. FIG. 11 is a perspective view of the paper guide member. FIG. 12 is a schematic left side view of the duplex printing unit, and FIG. 13 is a schematic left side view similar to FIG. 12, showing a state in which the paper guide member is opened. In the configuration of this embodiment, the same components as those in the first and second embodiments described with reference to FIGS. 2 to 7 and FIG. Shall.

  In the third embodiment, the duplex printing unit 12 shown in FIG. 1 is designed with the same configuration as the paper transport unit 30 described in the first embodiment. That is, as shown in FIG. 9, the double-sided printing unit 12 is mainly composed of a base portion 90 and a paper guide portion 100, and can be pulled out from the main body 2 of the image forming apparatus 1 in the horizontal direction. . On the left and right side surfaces of the base portion 90, a slide unit 91 for pulling out the duplex printing unit 12 is provided between the frame 2 a of the main body 2. A paper transport unit 30 similar to that described in the first embodiment is disposed immediately below the right portion of the duplex printing unit 12.

  As shown in FIGS. 9 and 10, the base portion 90 corresponds to the main body portion of the duplex printing unit 12, and the paper guide member 100 is provided below the base portion 90. Between the base portion 90 and the sheet guide member 100, a sheet conveyance path 110 that conveys the sheet P from the upper side to the left side and the lower side of the reversing roller 92 and rightward in the horizontal direction is provided. The base portion 90 constitutes one surface on the upper side of the sheet conveying path 110, and the sheet guide member 100 constitutes one surface on the lower side.

  The reverse roller 92 is provided in the left portion of the base portion 90, and a feed direction switching portion 93 is disposed on the upper right side of the reverse roller 92. In order to perform duplex printing, the paper P sent from the discharge / branch unit 11 to the duplex printing unit 12 shown in FIG. 1 enters the feed direction switching unit 93 from the upper left to the right in FIG. And temporarily stored. Next, the feeding direction of the paper P is switched to the left, and the paper P is sent to the paper transport path 110 from the upper side of the reversing roller 92 to the lower side through the left side (see FIG. 10). The paper P that has passed through the paper transport path 110 is then sent to the transfer section 9 via the paper transport section 4 and the registration rollers 5 (see FIG. 1).

  As shown in FIGS. 11 to 13, the paper guide member 100 is supported on the base portion 90 by a rotation shaft 101 provided at an end portion on the back side thereof. The sheet guide member 100 is rotatable in a vertical plane parallel to the front-rear direction, with the rotation shaft 101 as the center and the front end as a free end. As described above, the sheet guide member 100 is provided below the base portion 90, and is displaced by being displaced downward to be opened. On the side surface on the front side of the paper guide member 100, there is provided a handle 102 to be put on when the paper guide member 100 is opened. By opening the paper guide member 100 with respect to the base portion 90, the paper transport path 110 can be exposed.

  As shown in FIGS. 10, 12, and 13, a biasing means 120 for the paper guide member 100 is provided in the vicinity of the left side surface of the paper guide member 100. The urging means 120 includes a spring 121 and a wire 122. As shown in FIG. 12, the spring 121 is constituted by a tension coil spring, one end of which is attached to a support portion 94 provided on the side wall on the back side of the base portion 90, and extends toward the front in the horizontal direction. A wire 122 is connected to the other end of the spring 122. The wire 122 extends toward the front of the duplex printing unit 12, is hooked on a pin 95 provided at the front portion of the base portion 90, changes its direction downward, and the other end is provided at the front portion of the paper guide member 100. It is attached to the wire attaching portion 103. As shown in FIG. 13, when the paper guide member 100 is opened downward, the spring 121 is expanded by being pulled by the wire 122, and an elastic force acts on the spring 121. In this way, the urging unit 120 urges the opened sheet guide member 100 upward, which is the direction in which the sheet guide member 100 is closed.

  As shown in FIG. 11, an engaging portion 104 is provided on the upper surface of the front portion of the paper guide member 100. The engaging portion 104 has a protruding shape that protrudes upward by a predetermined amount from the upper surface of the paper guide member 100. A movement restriction surface (not shown) is provided at a position corresponding to the engagement portion 104 on the bottom surface of the base portion 90. When the paper guide member 100 is closed, the engaging portion 104 abuts against the movement restricting surface, and the paper guide member 100 urged upward by the urging means 120 cannot move upward more than necessary. . That is, the sheet guide member 100 is held at an appropriate position in the vertical direction by the engaging portion 104 and the movement restricting surface.

  Positioning pins 105 are provided on each of the upper surfaces of the front and rear portions of the paper guide member 100. The positioning pin 105 protrudes from the upper surface of the paper guide member 100 by a predetermined amount. A positioning hole (not shown) is provided on the bottom surface of the base portion 90 at a position corresponding to the positioning pin 105. When the paper guide member 100 is closed, the positioning pin 105 is inserted into the positioning hole, so that the paper guide member 100 cannot move in the horizontal direction due to the shakiness of the rotating shaft 101 portion or the like. That is, the sheet guide member 100 is held at an appropriate position in the horizontal direction by the positioning pins 105 and the positioning holes.

  As illustrated in FIG. 10, the sheet conveyance path 110 is provided between the base portion 90 and the sheet guide member 100. In the paper conveyance path 110, the engaging portion 104 (see FIG. 11) of the paper guide member 100 abuts against a movement restriction surface (not shown) of the base 90, and the upward movement of the paper guide member 100 is restricted. As a result, the base portion 90 and the paper guide member 100 are formed.

  A pair of conveyance rollers 111 and 112 is provided in the sheet conveyance path 110. The conveyance roller pair 111 includes a reverse roller 92 that is a conveyance roller provided on the base portion 90 and a pinch roller 111 b provided on the paper guide member 100. Similarly, the conveyance roller pair 112 includes a conveyance roller 112a and a pinch roller 112b. The pinch rollers 111 b and 112 b are urged upward by an elastic member (not shown) provided on the paper guide member 100. The paper P transported through the paper transport path 110 is inserted into a transport nip formed by pressing the reversing roller 92, the transport roller 112a, and the pinch rollers 111b and 112b with a predetermined pressure.

  As shown in FIG. 13, when the paper guide member 100 is opened, the reverse roller 92, the transport roller 112a, and the pinch rollers 111b and 112b are separated to expose the paper transport path 110. Thus, when a paper jam occurs in the paper transport path 110, the staying paper P can be easily taken out.

  As shown in FIG. 10, pressure generating members 80 are provided at the lower portions of the left and right end portions of the paper guide member 100. One each of the left and right pressure generating members 80 is provided at the end on the front side.

  9 and 10, as described above, immediately below the duplex printing unit 12, that is, outside the sheet guide member 100 in the opening direction, the sheet conveyance unit 30 is formed on the right side, and the image is formed on the left side. A frame 2 a that is an internal structural member of the main body 2 of the apparatus 1 is provided. Support surfaces 43 and 2b are provided at positions corresponding to the pressure generating member 80 on the upper surface of the base portion 40 of the paper transport unit 30 and the bottom surface of the frame 2a. When the duplex printing unit 12 is inserted into the main body 2, the pressure generating member 80 comes into contact with the support surfaces 43 and 2b. As a result, the paper guide member 100 is supported on the support surface 43 of the base portion 40 of the paper transport unit 30 and the support surface 2b of the main body 2 via the pressure generating member 80, and the transport roller pairs 111 and 112 are supported. A conveying nip is formed by pressure contact with a predetermined pressure.

  On the other hand, in the third embodiment, the paper transport unit 30 is provided immediately below the duplex printing unit 12 as described above. Accordingly, the base portion 90 of the duplex printing unit 12 is positioned outside the paper guide member 50 (see FIG. 3) of the paper transport unit 30 in the opening direction (see FIG. 9). As a result, the sheet guide member 50 is supported on the support surface (not shown) of the bottom of the base portion 90 via the pressure generating member 80, and the conveying roller pair 61 is pressed against the conveying nip with a predetermined pressure. Form.

  In this way, the paper transport unit provided in the image forming apparatus of the present invention is arranged above the downstream large-capacity paper cassette 22B, like the paper transport unit 30 shown in the first embodiment. It is not limited. That is, like the double-sided printing unit 12 shown in the third embodiment, the paper transport unit supports the paper guide member that opens and closes with respect to the base portion in contact with the image forming apparatus main body and other components. As long as it can be configured, it may be arranged in another place.

  The paper transport unit does not have to be a horizontal paper transport path provided in the paper transport unit, and may be a paper transport unit having a vertical paper transport path or a slanted paper transport path.

  Further, the spring 81 that supports the pressure generating member 80 and biases upward is not limited to a compression coil spring, and a plate spring, rubber, or the like, which is another elastic member, may be used.

  Although the embodiment of the present invention has been described above, various modifications can be made without departing from the spirit of the present invention.

  The present invention can be used in an image forming apparatus provided with a unit having a base portion and an opening / closing member that opens and closes with respect to the base portion so that the unit can be pulled out from the main body.

1 is a schematic vertical sectional front view showing a schematic configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a perspective view of a paper transport unit provided in the image forming apparatus according to the first embodiment of the present invention. FIG. 2 is a schematic vertical sectional front view showing a schematic configuration of a paper transport unit provided in the image forming apparatus according to the first embodiment of the present invention and its periphery. FIG. 4 is a schematic horizontal cross-sectional top view showing a schematic configuration of the paper transport unit shown in FIG. Fig. 3 is a schematic vertical sectional front view of the paper transport unit shown in Fig. 3 and shows a state in which the paper guide member is opened. FIG. 4 is a right side view of a schematic partial enlarged vertical section of the paper transport unit shown in FIG. 3. FIG. 4 is a right side view of a vertical section of a pressure generating member of the paper transport unit shown in FIG. 3. These are the right side views of the vertical cross section of the pressure generating member of the paper transport unit provided in the image forming apparatus according to the second embodiment of the present invention. These are the partial front views of the periphery of the unit for double-sided printing with which the image forming apparatus which concerns on the 3rd Embodiment of this invention was equipped. FIG. 10 is a schematic partial enlarged front view showing a part of FIG. 9 in an enlarged manner. FIG. 11 is a perspective view of a paper guide member of the duplex printing unit shown in FIG. 10. FIG. 11 is a schematic left side view of the duplex printing unit shown in FIG. 10. Fig. 12 is a schematic left side view similar to Fig. 12, showing a state in which the paper guide member is opened.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Main body 2a Frame 2b Support surface 4 Paper conveyance part 12 Duplex printing unit (paper conveyance unit)
20 cassette-type paper feed unit 22 large-capacity paper cassette 22A upstream large-capacity paper cassette 22B downstream large-capacity paper cassette 30 paper transport unit 40 base unit 41 guide roller 42 movement regulating surface 43 support surface 50 paper guide member 51 rotating shaft 52 Engagement projection 53 Frame 60 Paper transport path 61 Transport roller pair 61a Transport roller 61b Pinch roller 62 Spring (elastic member)
80 Pressure generating member 81 Spring (elastic member)
82 Guide roller (rolling member)
90 Base 92 Reversing roller (Conveying roller)
DESCRIPTION OF SYMBOLS 100 Paper guide member 101 Rotating shaft 104 Engagement part 110 Paper conveyance path 111,112 Conveyance roller pair 112a Conveyance roller 111b, 112b Pinch roller 120 Energizing means

Claims (7)

Each of a base part constituting one surface of the paper transport path, a paper guide member constituting the other face, capable of opening and closing the base part and exposing the paper transport path, and each of the base part and the paper guide member In the image forming apparatus provided with a paper transport unit provided with a pair of transport rollers that transport the paper between the rollers provided on the main body so that the paper transport unit can be pulled out from the main body in the horizontal direction.
When the paper transport unit is inserted into the main body with the paper guide member closed, the paper guide member contacts the support surface provided on the outer side in the opening direction of the paper guide member via the pressure generating member. The image forming apparatus is characterized in that the conveying roller pair is brought into pressure contact with a predetermined pressure to form a conveying nip.   The image forming apparatus according to claim 1, wherein the base portion includes a movement restriction surface that restricts movement of the paper guide member when the paper guide member is closed.   The image forming apparatus according to claim 1, wherein the pressure generating member includes a rolling member at a tip thereof.   The image forming apparatus according to claim 1, wherein the pressure generating member is supported by the paper guide member via an elastic member.   One of the rollers constituting the conveying roller pair is supported via an elastic member, and the elastic force of the elastic member is interposed between the pressure generating member and the paper guide member. The image forming apparatus according to claim 4, wherein the image forming apparatus has a smaller resilience.   4. At least one of the support surface and a contact surface of the pressure generating member with the support surface is configured by an elastic member. Image forming apparatus.   The image forming apparatus according to claim 1, wherein the sheet guide member contacts the support surface at a plurality of locations.

Images