JP5100428B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus that includes a paper feed cassette that is detachably attached to an apparatus main body, and an opening / closing member that is openably provided on the apparatus main body.

  In some conventional image forming apparatuses such as facsimile machines, copiers, and printers, a sheet cassette for storing sheets is detachably attached to the apparatus body in a direction perpendicular to the sheet feeding direction. . In such an image forming apparatus, at the time of image formation, sheets stored in a sheet feeding cassette are sequentially fed to an image forming unit by a sheet feeding roller, and the image forming unit forms an image on the sheet.

  By the way, in such a conventional image forming apparatus, a replacement part such as a process cartridge integrally including a photosensitive drum, a developing unit and the like constituting the image forming unit is detachably mounted from the same direction as the paper feed cassette. There is what has been made (see Patent Document 1).

  In addition, in the conventional image forming apparatus, an opening / closing member is provided in the apparatus main body so as to be openable and closable in order to replace a process cartridge or the like and supply a sheet. As this opening / closing member, there is a member that can be opened to the same side as the attachment / detachment side of the process cartridge or the like and the attachment / detachment side of the sheet cassette, and the opening / closing locus does not interfere with the attachment / detachment locus of the sheet cassette (patent) Reference 2).

JP 2006-308771 A JP 2001-18956 A

  By the way, in such a conventional image forming apparatus, in order to reduce the size of the apparatus, it is necessary to reduce the interval between a replacement part such as a process cartridge and a paper feed cassette. On the other hand, in order not to impair the detachability (replaceability) of the replacement part, it is necessary to keep a large distance between the opened / closed member and the replacement part to be attached / detached when the replacement part is attached / detached. .

  In this case, since the interval between the replacement part and the sheet feeding cassette is reduced, it is necessary to share the mounting / demounting space of the sheet feeding cassette and the opening / closing space of the opening / closing member in order to keep the distance between the replacement part and the opening / closing member large.

  Note that a plurality of sheet passing ribs for guiding the sheet are provided in a sheet passing area through which the sheet fed by the sheet feeding roller at the downstream end of the sheet feeding direction of the sheet feeding cassette passes. When the paper feeding cassette is downsized, the paper passing rib protrudes upward from the paper feeding cassette.

  Here, when the opening / closing member is opened in such a state that the sheet feeding cassette with the sheet passing rib protruding upward is pulled out, the opening / closing member may collide with the sheet passing rib, and the sheet passing rib may be scratched or dented. . If the paper passing rib is scratched or dents in this way, the sheet may be skewed or jammed.

  Accordingly, the present invention has been made in view of such a situation, and provides an image forming apparatus capable of preventing a sheet passing region of a sheet feeding cassette from being damaged when an opening / closing member is opened. It is intended.

  The present invention provides an image forming apparatus in which a sheet feeding cassette for storing sheets is detachably attached to an apparatus main body, and the sheet stored in the sheet feeding cassette is fed to an image forming unit to form an image on the sheet. An opening / closing member provided in the apparatus main body so as to be openable on the same side as the attachment / detachment side of the paper feed cassette, and configured to enter a drawer area of the paper feed cassette when opened, and the paper feed cassette When attaching to and detaching from the apparatus main body, the sheet feeding cassette is moved to a position where the sheet passing area through which the sheet fed to the image forming unit of the sheet feeding cassette passes does not come into contact with the opening / closing member to be opened. And an urging mechanism for urging so as to be performed.

  As in the present invention, when the paper feed cassette is attached or detached, the paper feed cassette is biased so as to move to a position that does not contact the open / close member where the sheet passage area is opened, thereby opening the open / close member. It is possible to prevent the sheet passing area of the sheet feeding cassette from being damaged.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a diagram showing a configuration of an image forming apparatus according to a first embodiment of the present invention. In FIG. 1, 100 is an image forming apparatus, 100a is an image forming apparatus main body (hereinafter referred to as an apparatus main body), An image forming unit 110 forms an image on a sheet.

  Here, the image forming unit 110 includes a photosensitive drum 1 (1a to 1d) and the like, and a process cartridge that forms toner images of four colors of yellow, magenta, cyan, and black, which are detachably attached to the apparatus main body 100a. 7 (7a-7d). The image forming unit 110 is an exposure device 3 and a fixing unit that are arranged vertically below the process cartridge 7 and irradiate a laser beam based on image information to form an electrostatic latent image on the photosensitive drum 1. A fixing roller pair 14 and the like are provided.

  Here, each process cartridge 7 attaches toner to the electrostatic latent image formed on the photosensitive drum 1, charging means 2 (2 a to 2 d) for uniformly charging the surface of the photosensitive drum in addition to the photosensitive drum 1. And a developing unit 4 (4a to 4d) that visualizes the toner image.

  Note that the photosensitive drum 1 as an image carrier is rotatably supported at both ends by flanges, and a driving force is transmitted to a first end from a driving motor (not shown), so that an arrow in FIG. Is rotated in the clockwise direction shown in FIG. The charging means 2 is a conductive roller formed in a roller shape, and the conductive roller is brought into contact with the surface of the photosensitive drum, and a charging bias voltage is applied by a power source (not shown), thereby the photosensitive drum. Charge the surface uniformly.

  The developing unit 4 includes a toner storage unit that stores toner of each color of yellow, magenta, cyan, and black. A developing roller 24 (24a to 24d) that is adjacent to the surface of the photosensitive drum, is rotated by a driving unit (not shown), and performs development by applying a developing bias voltage from a developing bias power source (not shown), and development An agent application roller 25 (25a to 25d) is provided.

  Reference numeral 12 denotes an intermediate transfer belt unit. The intermediate transfer belt unit 12 includes an intermediate transfer belt 12e stretched around a driving roller 12f and a tension roller 12g that applies tension in the direction of arrow E. Further, primary transfer rollers 12a to 12d are arranged inside the intermediate transfer belt 12e so as to face the respective photosensitive drums 1.

  Then, by applying a primary transfer bias to the intermediate transfer belt 12e by the primary transfer rollers 12a to 12d, the respective color toner images on the photosensitive drum are sequentially transferred to the intermediate transfer belt 12e, and thus on the intermediate transfer belt. A full color image is formed.

  Reference numeral 15 denotes a secondary transfer unit that sequentially transfers the full-color image formed on the intermediate transfer belt 12e to the sheet P. Reference numeral 20 denotes a discharge unit that discharges the sheet P on which the image has been fixed by the fixing roller pair 14 to the discharge tray 21. Is a pair of discharge rollers.

  Reference numeral 5 (5a to 5d) denotes a cleaner unit which is provided in the process cartridge 7 and removes the transferred toner remaining on the surface of the photosensitive drum after the toner image is transferred to the intermediate transfer belt 12e. The cleaner unit 5 includes a drum cleaning blade 8 (8a to 8d) for removing the post-transfer toner remaining on the photosensitive drum 1, and a waste toner container.

  Reference numeral 13 denotes a sheet feeding apparatus. The sheet feeding apparatus 13 includes a sheet feeding roller 9 that feeds the sheet P from the sheet feeding cassette 11 that stores the sheet P, and a sheet P that is fed by the sheet feeding roller 9. A conveying roller pair 10 for conveying the.

  Next, an image forming operation of the image forming apparatus 100 configured as described above will be described.

  When the image forming operation is started, first, the exposure device 3 irradiates laser light based on image information from a personal computer (not shown), and the surface of the photosensitive drum 1 whose surface is uniformly charged with a predetermined polarity and potential. The surface is sequentially exposed to form an electrostatic latent image on the photosensitive drum 1. Thereafter, the electrostatic latent image is developed with toner and visualized.

  For example, first, the exposure device 3 irradiates the photosensitive drum 1a with laser light based on the image signal of the yellow component color of the document, thereby forming a yellow electrostatic latent image on the photosensitive drum 1a. The yellow electrostatic latent image is developed with yellow toner from the developing unit 4a to be visualized as a yellow toner image.

  Next, when this toner image arrives at the primary transfer portion where the photosensitive drum 1a and the intermediate transfer belt 12e come into contact with the rotation of the photosensitive drum 1a, the photosensitive drum is driven by the primary transfer bias applied to the primary transfer roller 12a. The upper yellow toner image is transferred onto the intermediate transfer belt.

  Next, when the portion of the intermediate transfer belt 12e carrying the yellow toner image moves, the magenta toner image formed on the photosensitive drum 1b by the same method as described above is transferred from the yellow toner image to the intermediate transfer belt. 12e is transferred. Similarly, as the intermediate transfer belt 12e moves, a cyan toner image and a black toner image are transferred onto the yellow toner image and the magenta toner image, respectively, in the primary transfer portion.

  As a result, a full-color toner image is formed on the intermediate transfer belt. The toner remaining on the surface of the photosensitive drum 1 after the transfer of the toner image is removed by the cleaning blade 8 of the cleaner unit 5, and the removed toner is collected in a waste toner container in the cleaner unit 5.

  In parallel with this toner image forming operation, the sheets P accommodated in the sheet feeding cassette 11 are fed by the sheet feeding roller 9 and then separated one by one by the separation pad 23. After being separated in this way, the sheet P reaches the registration roller 17 by the conveyance roller 10, the timing is adjusted by the registration roller 17, and then conveyed to the secondary transfer unit 15.

  In the secondary transfer unit 15, the four color toner images on the intermediate transfer belt are collectively transferred onto the sheet by the secondary transfer bias applied to the secondary transfer roller 16. After the secondary transfer onto the sheet P, the toner remaining on the intermediate transfer belt is removed by the transfer belt cleaning device 22, and the removed toner is collected as a waste toner (not shown) disposed on the back surface of the device. It is collected in a container.

  Next, the sheet P onto which the toner image has been transferred in this way is conveyed to a pair of fixing rollers 14 for fixing the image formed on the sheet by applying heat and pressure. The fixing roller pair 14 includes a cylindrical fixing belt 14a guided by a belt guide member 14c to which a heating unit such as a heater is bonded, and an elastic pressure roller 14b.

  Here, the elastic pressure roller 14b forms a fixing nip portion N having a predetermined width with a predetermined pressure contact force with the belt guide member 14c with the fixing belt 14a interposed therebetween, and is rotationally driven by a driving means (not shown). When the elastic pressure roller 14b rotates, the cylindrical fixing belt 14a rotates accordingly. At this time, the fixing belt 14a is heated by an internal heater (not shown), and the fixing nip portion N has a predetermined temperature. Become.

  When a sheet P on which an unfixed toner image is formed is introduced into the fixing nip N at a predetermined temperature, the image surface of the sheet P closely contacts the outer surface of the fixing belt 14a in the fixing nip N. The fixing nip portion N is nipped and conveyed together with the fixing belt 14a.

  Here, in the process in which the sheet P is nipped and conveyed together with the fixing belt 14a through the fixing nip portion N in this way, the unfixed toner on the sheet is melted and mixed by being heated by the heater heat in the fixing belt 14a. It is fixed on the sheet P as a full-color image. Thereafter, the sheet P on which the full-color image has been fixed is discharged onto a discharge tray 21 by a discharge roller pair 20 provided downstream of the fixing roller pair 14.

  By the way, in the present embodiment, the paper feed cassette 11 is detachably attached to the apparatus main body 100a and is configured to be pulled out toward the front of the apparatus main body in FIG. When supplying sheets to the sheet cassette 11, first the sheet cassette 11 is pulled out from the apparatus main body 100a, the sheet P is set, and then inserted (attached) into the apparatus body 100a to complete sheet supply. To do.

  On the other hand, for example, the process cartridge 7 (7a to 7d) is also detachable in the same direction as the paper feed cassette 11 as shown in FIG. Here, when detaching the process cartridge 7 in this way, as shown in FIG. 2, the door 101 which is an opening and closing member provided on the side surface of the exterior of the apparatus main body 100a is opened and closed. As shown in FIG. 3, the sheet cassette 11 can be opened to the same side as the attachment / detachment side. The door 101 is opened and closed vertically by a hinge provided on the lower side (not shown).

  In this configuration, when the process cartridge 7 is attached / detached as shown in FIG. 2, in order to prevent interference between the process cartridge 7 and the door 101 and to improve the operability, the distance between the process cartridge 7 and the door 101 is set. Need to be larger.

  Here, in order to reduce the size of the apparatus main body 100a and increase the distance from the process cartridge 7, when the door 101 indicated by the alternate long and short dash line in FIG. It is necessary to enter (within the drawer area). However, in the case of such a configuration, when the door 101 is opened in a state where the paper feeding cassette 11 is stopped in the middle of attachment / detachment as shown in FIG. 3, the corner 101P at the lower end of the door 101 is at a position indicated by X. Interference (contact) with the paper feed cassette 11.

  By the way, as shown in FIG. 5, a plurality of sheets extending in the sheet feeding direction are provided in the sheet passing region R through which the sheet fed by the sheet feeding roller at the downstream end of the sheet feeding direction of the sheet feeding cassette 11 passes. A paper passing rib 11a is provided in a protruding manner.

  When the door 101 is opened, if the corner 101p at the lower end of the door 101 interferes (contacts) with the sheet passing rib 11a, the sheet passing rib 11a is scratched or dented, and the sheet is skewed. Or jam.

  Therefore, in the present embodiment, when the paper cassette 11 is attached or detached, even if the door 101 is opened, the paper cassette 11 is moved to a position where the paper passing rib 11a is not damaged. A toggle mechanism is provided as an example of the urging mechanism for energizing. That is, in the present embodiment, when the paper cassette 11 is attached / detached, even when the door 101 is opened by the toggle mechanism, the paper cassette 11 is moved to a position where the paper passing rib 11a is not damaged. I try to move it.

  FIG. 6 is a perspective view showing the configuration of the toggle mechanism according to the present embodiment. In FIG. 6, 11c is a boss protruding from the bottom surface of the paper feed cassette 11, and 30A is a toggle mechanism.

  The toggle mechanism 30A is engaged with a lever 30 rotatably provided on the apparatus main body with a shaft 30b as a fulcrum, and a shaft provided with one end protruding from the lever 30 and a boss 30c provided on the lever 30 with the other end provided on the apparatus main body. And a spring 31 locked to 32. A notch groove 30 a for receiving the boss 11 c of the paper feed cassette 11 is formed at the rotating end of the lever 30.

  Here, FIG. 6 shows a state in which the paper feed cassette 11 is urged by the toggle mechanism 30A to move to a position away from a position where the corner 101P at the lower end of the door 101 interferes with the paper passing rib. Yes. At this time, the boss 11c of the sheet feeding cassette 11 is in a notch groove 30a formed at the rotating end of the lever 30.

  Next, when the paper cassette 11 is pulled out from this state in the arrow direction 11o, the lever 30 rotates integrally with the boss 11c provided on the paper cassette 11 with the shaft 30b as a fulcrum. When the paper feeding cassette 11 is pulled out in this way, a force is applied to the paper feeding cassette 11 in the direction of pulling in the paper feeding cassette 11 by the toggle mechanism 30A (spring 31). Therefore, when the hand is released from the paper feed cassette 11, the paper feed cassette 11 returns to the position shown in FIG. 6 by the toggle mechanism 30A.

  Next, the sheet feed cassette 11 reaches a position where the intermediate position of the sheet passing rib reaches the position X shown in FIGS. 3 and 4 (hereinafter referred to as an interference position) that interferes with the door 101 when the door 101 is opened. When pulled out, the toggle mechanism 30A is in a neutral state shown in FIG.

  Thereafter, when the paper feed cassette 11 is further pulled out in the arrow direction 11o, the paper feed cassette 11 reaches a position where the paper feeding rib shown in FIG. After that, when the paper feed cassette 11 is pulled out, the boss 31 c is separated from the groove 30 c of the lever 30.

  When the paper feed cassette 11 is pulled out after the toggle mechanism 30A shown in FIG. 7A is in a neutral state as described above, the paper feed cassette 11 is fed by the toggle mechanism 30A (spring 31). A force is applied in the direction of pulling out the paper cassette 11. Therefore, when the hand is released from the paper feed cassette 11, the paper feed cassette 11 reaches a position where the paper passing rib 11a shown in FIG.

  As described above, when the sheet passing rib 11a of the front half region R2 which is the downstream portion of the sheet passing region R shown in FIG. The mechanism 30A is between the state shown in FIG. 6 and the state shown in FIG. For this reason, a force is applied to the paper feed cassette 11 in the insertion direction, which is opposite to the direction of the arrow 11o. When the door 101 is opened, if the hand is accidentally released from the paper feed cassette 11, The paper cassette 11 is returned to the position shown in FIG. 6 by the toggle mechanism 30A.

  On the other hand, when the sheet feeding cassette 11 is in the interference position X with the door 101 in the second half area R1 of the sheet passing area R shown in FIG. 30A is between the state shown in FIG. 7A and the state shown in FIG. 7B. Therefore, a force is applied to the paper feeding cassette 11 in the direction of pulling out the arrow 11o, and when the door 101 is opened, if the hand is accidentally released from the paper feeding cassette 11, the paper feeding cassette 11 is toggled. The mechanism 30A moves to the position shown in FIG.

  Although the case where the paper feed cassette 11 is pulled out has been described so far, the toggle mechanism 30A acts similarly when the paper feed cassette 11 is mounted in the apparatus main body. That is, when the paper feeding cassette 11 is mounted, when the paper passing rib 11a in the second half area R1 of the sheet passing area R is at the interference position X with the door 101, the paper feeding cassette 11 is moved in the pulling direction by the toggle mechanism 30A. It is energized as follows. When the sheet passing rib 11a in the first half area R2 of the sheet passing area R is at the interference position X with the door 101, the toggle mechanism 30A biases the sheet feeding cassette 11 to move in the insertion direction (mounting direction). .

  Thus, in the present embodiment, when the sheet passing rib 11a in the first half area R2 of the sheet passing area R is at the interference position X with the door 101, the toggle mechanism 30A moves the sheet feeding cassette 11 in the insertion direction. Is energized. When the sheet passing rib 11a in the second half area R1 of the sheet passing area R is at the interference position X with the door 101, the toggle mechanism 30A biases the sheet feeding cassette 11 to move in the pulling direction.

  That is, in the present embodiment, when the paper feed cassette 11 is attached or detached, the toggle mechanism 30A biases the paper feed cassette 11 to a position where it does not contact the door 101 where the sheet passing region R is opened. Like to do. In other words, the paper feed cassette 11 is configured not to stop in a region where the door 101 interferes with the paper passing rib 11a when the door 101 is opened. Thereby, when the door 101 is opened, it is possible to prevent the sheet passing region R of the sheet feeding cassette 11 from being damaged. As a result, sheet skew and jamming can be prevented.

  In the present embodiment, when the paper feed cassette 11 is attached or detached, the reaction force is generated only in the sheet passing region R in the paper feed cassette 11, so that the region where the reaction force is generated can be reduced. As a result, the toggle mechanism 30A can be reduced in size, and accordingly, the operation can be simplified and the apparatus main body can be reduced in size.

  Next, a second embodiment of the present invention will be described.

  FIG. 8 is a side view showing the configuration of the urging mechanism provided in the image forming apparatus according to the present embodiment. In FIG. 8, reference numeral 46 denotes an urging mechanism for urging the sheet feeding cassette 11 to move it to a position deviated from an area where it is desired to prevent generation of scratches and dents on the sheet passing rib 11a. The urging mechanism 46 includes a cam portion 45 provided on the outer surface of the side wall parallel to the attachment / detachment direction of the paper feed cassette 11, and a pressing portion 40 </ b> A provided in the apparatus main body and elastically pressed against the cam portion 45. It is comprised by.

  Here, the cam portion 45 has cam surfaces C1 and C2 corresponding to the first half region R2 and the second half region R1 of the sheet passing region R, and is formed so that the central portion of the sheet passing region R is the highest. The pressing portion 40A constituting the cam follower includes a roller 40 that rotates along the cam portion 45, a holder 41 that rotatably holds the roller 40, a holder 41 that is movable in the vertical direction, and a holder A spring 42 for applying a load in the vertical direction to 41 is provided.

  8 and 9 show a state in which the paper feed cassette 11 is mounted on the apparatus main body. When the paper feed cassette 11 is pulled out from this state in the arrow direction 11o, the roller 40 follows the cam surface C1. And move up.

  Here, when the paper feeding cassette 11 is pulled out in this way, when the front half region R2 of the paper feeding rib 11a shown in FIG. 42), the cam surface C1 is pressed. For this reason, a force is applied to the paper feed cassette 11 in the insertion direction. If the hand is accidentally released from the paper feed cassette 11, the paper feed cassette 11 is moved to FIGS. 8 and 9 by the pressing force of the pressing portion 40A. It returns to the position shown.

  After that, when the sheet feeding cassette 11 is continuously pulled out and the intermediate position of the sheet passing rib 11a reaches the interference position X, the roller 40 is located at the boundary between the cam surfaces C1 and C2 as shown in FIG. It becomes.

  Thereafter, when the sheet feeding cassette 11 is further pulled out in the arrow direction 11o, the cam surface C2 is pressed by the pressing portion 40A (the spring 42). For this reason, a force is applied to the paper feed cassette 11 in the pull-out direction. If the hand is accidentally released from the paper feed cassette 11, the paper feed cassette 11 is moved to the position shown in FIG. The latter half region R1 of the illustrated sheet passing rib reaches a position deviating from the interference position X. After that, when the paper feed cassette 11 is pulled out, the roller 40 moves away from the cam surface C2.

  As described above, in the present embodiment, when the paper feeding cassette 11 is pulled out, when the paper feeding cassette 11 is in the interference position X with the door 101, the pressing portion 40A is It acts on the cam surface C1. For this reason, a force is applied to the paper feed cassette 11 in the insertion direction, which is opposite to the direction of the arrow 11o. When the door 101 is opened, if the hand is mistakenly released, the paper feed cassette 11 is fed. The cassette 11 is returned to the position shown in FIGS. 8 and 9 by the urging mechanism 46.

  On the other hand, when the paper feed cassette 11 is in the position X where the second half region R1 of the paper passing rib is in the interference position X with the door 101, the pressing portion 40A acts on the cam surface C2. For this reason, a force is applied to the paper feed cassette 11 in the pulling direction indicated by an arrow 11o. When the door 101 is opened, if the hand is accidentally released from the paper feed cassette 11, the paper feed cassette 11 is The urging mechanism 46 moves to the position shown in FIG.

  Although the case where the paper feeding cassette 11 is pulled out has been described so far, the biasing mechanism 46 similarly acts when the paper feeding cassette 11 is mounted in the apparatus main body. That is, when the paper feeding cassette 11 is mounted, when the paper passing rib 11a in the second half area R1 of the sheet passing area R is at the interference position X with the door 101, the paper feeding cassette 11 is moved in the pulling direction by the biasing mechanism 46. Energize to do. When the sheet passing rib 11a in the first half area R2 of the sheet passing area R is at the interference position X with the door 101, the urging mechanism 46 urges the sheet feeding cassette 11 to move in the insertion direction.

  Thus, in the present embodiment, when the paper cassette 11 is attached or detached, the biasing mechanism 46 moves the paper cassette 11 to a position where it does not contact the door 101 where the sheet passing region R is opened. I am trying to be energized. Thereby, when the door 101 is opened, it is possible to prevent the sheet passing region R of the sheet feeding cassette 11 from being damaged.

  In the present embodiment, the cam portion 45 is provided in the paper feed cassette 11 and the pressing portion 40A is provided in the apparatus main body. However, the cam portion 45 is provided in one of the apparatus main body and the paper feed cassette, and the apparatus main body and the paper feed. A pressing portion 40A may be provided on the other side of the cassette.

  Next, a third embodiment of the present invention will be described.

  FIG. 11 is a perspective view showing a configuration of an urging mechanism provided in the image forming apparatus according to the present embodiment. In FIG. 11, reference numeral 56 denotes an urging mechanism for urging the sheet feeding cassette 11 to move it to a position deviated from an area where it is desired to prevent generation of scratches and dents on the sheet passing rib. The urging mechanism 56 includes a rack 55 provided on the outer surface of the side wall parallel to the attachment / detachment direction of the paper feed cassette 11, a gear (pinion) 50 provided on the apparatus main body and meshing with the rack 55, and rotation of the gear 50. And a spring 53 that expands and contracts with it.

  In the present embodiment, the rack 55 is provided corresponding to the sheet passing region R. The gear 50 is provided with a cylindrical shape 51, and the spring 53 is fixed to the other end of the wire 52 whose one end is fixed to the cylindrical shape 51. When the gear 50 rotates, the wire 52 is wound around a cylindrical shape 51 that rotates integrally with the gear 50, and the spring 53 is extended accordingly. As described above, in the present embodiment, the urging mechanism 56 includes the rack 55, the gear 50, and the power storage unit configured by the wire 52 and the spring 53.

  Here, FIG. 12A shows a state in which the paper feed cassette 11 is mounted on the apparatus main body. At this time, the gear 50 does not mesh with the rack 55 as shown in FIG. . In this state, since the wire 52 is not wound around the cylindrical shape 51 of the gear 50, no rotational force is applied to the gear 50.

  On the other hand, when the sheet cassette 11 in this state is pulled out, the gear 50 meshes with the rack 55 of the sheet cassette 11 as shown in FIG. 11 and FIG. Rotates counterclockwise, and accordingly, the wire 52 is wound around the cylindrical shape 51. When the wire 52 is wound in this manner, the spring 53 is pulled, and a reverse force, that is, a force that reversely rotates in the direction in which the paper feeding cassette 11 is inserted is applied to the gear 50 by the spring 53.

  For this reason, if the hand is accidentally released from the sheet cassette 11 in this state, the sheet cassette 11 returns to the position shown in FIG. 11 and FIG. Here, the position shown in FIG. 11 and FIG. 13A is a position where the sheet passing region R is deviated from the interference position X with the door 101.

  Thus, in the present embodiment, the paper feed cassette 11 is configured not to stop at a position where the door 101 interferes with the paper passing rib when the door 101 is opened. Thereby, when the door 101 is opened, it is possible to prevent the sheet passing region R of the sheet feeding cassette 11 from being damaged.

  On the other hand, when the paper cassette 11 is inserted into the apparatus main body as shown in FIG. 12B and the arrow 11i in FIG. 14, when the paper cassette 11 is inserted into the apparatus main body, As shown in FIG. 14, the gear 50 meshes with the rack 55 of the paper feed cassette 11. Further, after that, when the paper feeding cassette 11 is inserted, the gear 50 rotates clockwise, and the wire 52 is wound around the cylindrical shape 51 accordingly.

  When the wire 52 is wound in this way, the spring 53 is pulled, and the reverse force, that is, the force rotating in the direction of pulling out the paper feed cassette 11 is applied to the gear 50 by the spring 53. Therefore, if the hand is accidentally released from the sheet cassette 11 in this state, the sheet cassette 11 returns to a position where the gear 50 does not mesh with the rack 55.

  As described above, in the present embodiment, when the paper feeding cassette 11 is attached or detached, the biasing mechanism 56 moves the paper feeding cassette 11 to a position where it does not contact the door 101 where the sheet passing region R is opened. I am trying to energize it.

  In other words, in the present embodiment, when the rack 55 and the gear 50 are engaged, a force in the direction opposite to the attaching / detaching operation is applied. The position X that interferes with the corner portion 101P is not stopped. Thereby, when the door 101 is opened, it is possible to prevent the sheet passing region R of the sheet feeding cassette 11 from being damaged.

  In the description so far, the configuration in which all the sheet passing ribs are protected so that the entire sheet passing region R does not contact the door 101 has been described, but the present invention is not limited to this. For example, a configuration may be adopted in which the region is limited and protected, such as a rib positioned on the downstream side in the sheet feeding direction of the separating pad 23 that protrudes most among the plurality of ribs.

1 is a diagram illustrating a configuration of an image forming apparatus according to a first embodiment of the present invention. FIG. 3 is a perspective view showing a state when a process cartridge that is detachably attached to the image forming apparatus is attached / detached. FIG. 3 is a perspective view showing a state when a paper feed cassette detachably attached to the image forming apparatus is attached and when a door provided to the image forming apparatus is openable. The side view which shows the state at the time of the attachment or detachment of the said paper feed cassette, and the door opening. FIG. 4 is a perspective view for explaining a sheet passing area provided with a plurality of sheet passing ribs of the sheet feeding cassette. FIG. 3 is a perspective view illustrating a configuration of a toggle mechanism provided in the image forming apparatus. The figure explaining operation | movement of the toggle mechanism at the time of attaching or detaching the said paper feed cassette. FIG. 6 is a side view showing a configuration of an urging mechanism provided in an image forming apparatus according to a second embodiment of the present invention. The perspective view which shows the structure of the said urging | biasing mechanism. The figure explaining operation | movement of the biasing mechanism at the time of attaching or detaching the said paper feed cassette. FIG. 10 is a perspective view illustrating a configuration of an urging mechanism provided in an image forming apparatus according to a third embodiment of the present invention. The figure explaining operation | movement of the biasing mechanism at the time of attaching or detaching the said paper feed cassette. FIG. 3 is a first diagram illustrating a state in which a paper feed cassette is attached to and detached from a rack and a gear constituting the urging mechanism. FIG. 9 is a second diagram illustrating a state in which a paper feed cassette is attached to and detached from a rack and a gear constituting the urging mechanism.

Explanation of symbols

7 Process cartridge 11 Paper feed cassette 11a Paper passing rib 30A Toggle mechanism 40A Pressing part 45 Cam part 46 Energizing mechanism 50 Gear 52 Wire 53 Spring 55 Rack 56 Energizing mechanism 100 Image forming apparatus 100a Image forming apparatus main body 101 Door 101P Lower end corner portion 110 Image forming portion P Sheet R Sheet passage region R1 Second half region R2 upstream of the sheet passing region in the sheet feeding cassette pulling out direction First half region X upstream of the sheet passing region in the sheet feeding cassette pulling out direction Interference position

Claims (6)

In an image forming apparatus in which a sheet feeding cassette for storing a sheet is detachably attached to an apparatus main body, and the sheet stored in the sheet feeding cassette is fed to an image forming unit to form an image on the sheet.
An opening / closing member provided in the apparatus main body so as to be openable on the same side as the attachment / detachment side of the paper feed cassette, and configured to enter a drawer region of the paper feed cassette when opened;
When the sheet feeding cassette is attached to and detached from the apparatus main body, the sheet passing area through which the sheet fed to the image forming unit of the sheet feeding cassette passes is set to a position where the opening and closing member is not in contact. An urging mechanism for urging the sheet cassette to move;
An image forming apparatus comprising:   When the paper feeding cassette is attached to or detached from the apparatus main body, the biasing mechanism attaches the paper feeding cassette when the downstream portion of the sheet passing area is in contact with the opening / closing member that is opened. The sheet feeding cassette is configured to urge the sheet feeding cassette in the pulling direction when the upstream side portion in the pulling direction of the sheet passing region is in a position in contact with the opening / closing member that is opened. The image forming apparatus according to claim 1.   The image forming apparatus according to claim 1, wherein the urging mechanism is a toggle mechanism provided between the apparatus main body and the sheet feeding cassette.   The urging mechanism is provided on one of the apparatus main body and the paper feed cassette, and is provided on the other of the apparatus main body and the paper feed cassette. The image forming apparatus according to claim 1, further comprising a cam follower that is elastically pressed against the cam portion.   The urging mechanism includes a rack provided in the paper feed cassette, a pinion provided in the apparatus main body, and the pinion as the pinion rotates when the paper feed cassette is attached to and detached from the apparatus main body. The image forming apparatus according to claim 1, wherein the image forming apparatus includes a power storage unit that stores a reverse rotation force.   6. The image forming apparatus according to claim 1, wherein a plurality of sheet passing ribs extending in a sheet feeding direction are provided in the sheet passing area of the sheet feeding cassette. .

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