JP6043711B2 - Unit drawing-in device and image forming apparatus having the same - Google Patents

Description

  The present invention relates to a unit drawing device that draws a unit that can be pulled out and inserted into the apparatus main body into the apparatus main body, and an image forming apparatus such as a copying machine, a printer, and a facsimile equipped with the unit drawing apparatus.

  2. Description of the Related Art Conventionally, image forming apparatuses such as copiers, printers, facsimiles, and the like are provided with a paper feed cassette that accommodates a plurality of sheets (recording media) at the bottom of the apparatus main body so that the paper cassette can be pulled out from the image forming apparatus main body. The paper stored in the paper cassette is sequentially sent out one by one by a feeding means composed of a pick-up roller or the like disposed above the paper cassette and a separating and conveying means composed of a pair of paper feed rollers. The image is formed on a sheet by being conveyed to an image forming unit and a fixing device by a conveyance roller.

  In the image forming apparatus as described above, the paper feed cassette is attached to and detached from the apparatus main body manually by the user for replenishing paper or changing the paper size. At this time, the paper feed cassette may not be sufficiently inserted to a predetermined position (mounting position) of the apparatus main body. In such a case, the paper feed cassette is not positioned, and an image may not be accurately formed at the center in the width direction of the paper, or a conveyance failure may occur.

  Further, the total weight of the paper feed cassette and the weight of the filled paper is increased, and the operability when the paper feed cassette is inserted into the mounting position is deteriorated. In order to improve the operability of the paper feed cassette, various pull-in devices that draw the paper feed cassette into the mounting position in the apparatus main body have been proposed.

  For example, Patent Document 1 discloses a retracting device that releases a retracting force by disengaging the engaging portion of the retracting device after the paper feeding unit is mounted to a predetermined position. Further, Patent Document 2 has a power storage means for gradually storing a pulling force as the sheet storing means moves in the mounting direction after engaging the sheet storing means, and the pulling force by the pulling means is maximized. There is disclosed a sheet feeding apparatus that releases the pulling force of the power storage means before and after the pulling and pulls it to the mounting position.

  Further, Patent Document 3 discloses a retraction composed of a plurality of urging members that generate urging forces having different urging directions and a plurality of rotating members that generate a retraction force from the urging forces of the plurality of urging members. An image forming apparatus including a force generation unit is disclosed.

JP 2010-18406 A JP 2006-327823 A JP 2011-37540 A

  In the configuration of Patent Document 1, when the engaging portion is released, the force to keep the retracted paper feeding unit in a predetermined position does not work, and there is a possibility that the paper feeding unit may be separated from the predetermined position due to paper feeding vibration or the like. Further, in the configuration of Patent Document 2, a strong force is necessary to gradually store the pulling force in the power storage means, which places a burden on the user at the start of the mounting operation. Further, the configuration of Patent Document 3 has a problem that the number of parts for generating a pulling force increases and the operation becomes complicated.

  Note that here, the paper cassette is taken as an example to explain the problems during insertion and withdrawal operations. However, the present invention is not limited to the paper feed cassette, and can be pulled out from the apparatus main body, such as a duplex unit, a fixing unit, and a development unit. Similar problems arise for other units.

  In view of the above problems, the present invention provides a unit drawing device that can reliably pull a unit that can be attached to and detached from the device main body into a predetermined position within the device main body without applying a load to the user, and a unit drawing device that An object is to provide an image forming apparatus provided.

  In order to achieve the above object, a first configuration of the present invention includes a hook member and a pull-in force generation mechanism, and a unit that can be inserted into or pulled out from the apparatus main body is a pull-in completion position in the apparatus main body. It is a unit drawing-in device drawn in. The hook member engages with an engaged portion provided in the unit. The pull-in force generating mechanism causes the pull-in force to act on the hook member when the hook member and the engaged portion are engaged at the pull-in start position of the unit. The pull-in force generating mechanism is rotatably provided at the first rotation fulcrum, and one end is locked to the first rotation member having a hook member connected to the rotation side end. A biasing member that biases the first pivoting member in a direction in which the hook member pulls the unit into the apparatus main body, and the other end of the biasing member is locked, so that the second pivoting point can be pivoted. And a second rotating member provided. The second rotating member rotates in the same direction as the first rotating member as the first rotating member is rotated by the urging force of the urging member.

  According to the first configuration of the present invention, the first rotating member in which one end of the biasing member is locked and the second rotating member in which the other end of the biasing member is locked rotate in the same direction. The attenuation of the urging force due to the contraction of the urging member accompanying the retracting operation can be suppressed. Accordingly, it is possible to ensure a certain level of pulling force from the start of pulling in the unit to the completion of pulling in, so that the pulling operation can be performed smoothly.

Schematic sectional view of an image forming apparatus 100 provided with a unit drawing device 50 of the present invention External perspective view of image forming apparatus 100 viewed from the front side of FIG. External perspective view of paper feed cassette 10 mounted on image forming apparatus 100 The perspective view which shows the state which removed the cover of the unit drawing-in apparatus 50 The top view which shows typically the state of the unit drawing-in apparatus 50 before insertion of the paper feed cassette 10 (before drawing-in start). FIG. 5 is a plan view showing a state in which the paper feeding cassette 10 is inserted into the main body of the image forming apparatus 100 by a predetermined amount from the state of FIG. 5 and the engagement state between the claw portion 65a and the locking portion 63c is released. FIG. 6 is a plan view showing a state in which the paper feeding cassette 10 is further drawn from the state of FIG. 6 and the arm member 61 is rotated by a predetermined angle. FIG. 7 is a plan view showing a state in which the paper feeding cassette 10 is further drawn from the state of FIG. 7 and the arm member 61 is rotated by a predetermined angle. FIG. 9 is a plan view showing a state in which the engagement protrusion 80 has moved to the end point of the guide groove 51 a and the paper feed cassette 10 has been pulled to the paper feedable position (drawing completion position) in the image forming apparatus 100. Before the paper feed cassette 10 is inserted, the engaging portion 63c and the claw portion 65a are disengaged, and the engagement protrusion 80 and the hook member 63 are engaged even though the arm member 61 is in the retracted completion position. The top view of the unit drawing-in apparatus 50 which shows a state without

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view of an image forming apparatus 100 including a sheet feeding apparatus according to an embodiment of the present invention. FIG. 2 is an external view of the image forming apparatus 100 viewed from the front side (front side in FIG. 1). It is a perspective view. Here, a monochrome multifunction peripheral is shown as the image forming apparatus 100. In the main body of the image forming apparatus 100, an image forming portion P for forming a monochrome image by each process of charging, exposure, development and transfer is disposed.

  In the image forming portion P, along the rotation direction of the photosensitive drum 1 (counterclockwise direction in FIG. 1), the charging device 2, the exposure unit 3, the developing device 4, the transfer roller 7, the cleaning device 8, and the charge eliminating device. (Not shown) is provided. In the image forming unit P, the image forming process for the photosensitive drum 1 is executed while rotating the photosensitive drum 1 in the counterclockwise direction in FIG.

  The photosensitive drum 1 is formed by, for example, a photosensitive layer laminated on the surface of an aluminum drum, and the charging device 2 charges the surface. Then, the surface is irradiated with a laser beam from an exposure unit 3 to be described later, thereby forming an electrostatic latent image in which charging is attenuated. The above-mentioned photosensitive layer is not particularly limited. For example, amorphous silicon (a-Si) having excellent durability, or an organic photosensitive layer (high-resolution image can be obtained with little generation of ozone during charging). OPC) and the like are preferable.

  The charging device 2 uniformly charges the surface of the photosensitive drum 1. For example, a corona discharge device that discharges by applying a high voltage using a thin wire or the like as an electrode is used as the charging device 2. Instead of the corona discharge device, a contact-type charging device that applies a voltage in a state where a charging device material represented by a charging roller is in contact with the surface of the photoreceptor may be used. The exposure unit 3 irradiates the photosensitive drum 1 with a light beam (for example, a laser beam) based on the document image data read by the image reading unit 21 to form an electrostatic latent image on the surface of the photosensitive drum 1.

  The developing device 4 forms toner images by attaching toner to the electrostatic latent image on the photosensitive drum 1. The toner is supplied to the developing device 4 from the toner container 5 via the intermediate hopper 6. Here, a single-component developer (hereinafter also simply referred to as toner) composed only of magnetic toner components is accommodated in the developing device 4.

  The transfer roller 7 transfers the toner image formed on the surface of the photosensitive drum 1 to the sheet conveyed through the sheet conveyance path 11 without disturbing the toner image. The cleaning device 8 includes a cleaning roller, a cleaning blade, and the like that are in linear contact with the longitudinal direction of the photosensitive drum 1, and removes residual toner remaining on the surface of the photosensitive drum 1 after the toner image is transferred to the paper. To do.

  The image reading unit 21 includes a scanner lamp that illuminates the document during copying, a scanning optical system equipped with a mirror that changes the optical path of reflected light from the document, and a condensing lens that focuses the reflected light from the document to form an image. And a CCD sensor or the like (both not shown) that converts the imaged image light into an electrical signal, and reads a document image and converts it into image data.

  When performing the copy operation, the image reading unit 21 reads the image data of the document and converts it into an image signal. On the other hand, in the image forming unit P, the photosensitive drum 1 that rotates counterclockwise in FIG. 1 is uniformly charged by the charging device 2, and the exposure unit is based on the document image data read by the image reading unit 21. 3 irradiates the photosensitive drum 1 with a laser beam (light beam), thereby forming an electrostatic latent image based on the image data on the surface of the photosensitive drum 1. Thereafter, the developing device 4 attaches toner to the electrostatic latent image to form a toner image.

  The paper 18 is sent from the paper feed cassette 10 by the paper feed unit 12 toward the image forming part P on which the toner image is formed as described above, and the image forming part is passed through the paper transport path 11 and the registration roller pair 13. It is conveyed to P at a predetermined timing. Then, the toner image on the surface of the photosensitive drum 1 is transferred to the paper 18 by the transfer roller 7 in the image forming portion P. The sheet 18 on which the toner image has been transferred is separated from the photosensitive drum 1, conveyed to the fixing device 9, and heated and pressed to fix the toner image on the sheet 18.

  The transport direction of the paper 18 that has passed through the fixing device 9 is sorted by the branching section 16 that branches in a plurality of directions. When an image is formed on only one side of the paper 18, the image is directly discharged to the discharge tray 15 by the discharge roller pair 14.

  On the other hand, when images are formed on both sides of the paper 18, the paper 18 that has passed through the fixing device 9 is once transported in the direction of the discharge roller pair 14, and after the rear end of the paper 18 passes through the branch portion 16, the discharge roller pair 14. Is rotated in the reverse direction and the conveyance direction of the branching portion 16 is switched, so that the paper 18 is distributed from the rear end of the paper 18 to the reverse conveyance path 17 and re-conveyed to the registration roller pair 13 with the image surface reversed. Then, the next image formed on the photosensitive drum 1 is transferred to the surface of the paper 18 where the image is not formed by the transfer roller 7 and conveyed to the fixing device 9 to fix the toner image, and then the discharge tray. 15 is discharged.

  As shown in FIG. 2, on the upper surface of the image reading unit 21, an original table (not shown) on which a transparent glass plate (contact glass) is attached, or an operation that protrudes to the front side of the main body of the image forming apparatus 100. A panel 22 is provided. In addition, a platen (document retainer) 23 that presses the document placed on the document placement table is supported on the upper surface of the image reading unit 21 so as to be freely opened and closed.

  A front cover 24 is provided on the front side of the housing 100a so as to be openable and closable. By opening the front cover 24, maintenance and replacement of each member in the housing 100a is performed.

  FIG. 3 is an external perspective view of the paper feed cassette 10 mounted on the image forming apparatus 100. In FIG. 3, the front left side is the front side of the image forming apparatus 100 (the front side in FIG. 2). In FIG. 3, the insertion direction of the paper feed cassette 10 with respect to the housing 100a is indicated by an arrow A, the pull-out direction is indicated by an arrow A ', and the paper feed direction of the paper feed cassette 10 is indicated by an arrow B.

  As shown in FIG. 3, walls 25 a to 25 d are erected on the four peripheral edges of the cassette base 25 which is the bottom surface of the paper feed cassette 10. A cassette cover 33 is mounted on the wall portion 25 c on the upstream side with respect to the insertion direction of the paper feed cassette 10. The cassette cover 33 is exposed to the outside on the front side (left side in FIG. 3) and constitutes a part of the exterior surface of the main body of the image forming apparatus 100 (see FIG. 2). A grip portion 35 is provided at the center of the cassette cover 33 for gripping when the paper feed cassette 10 is attached or detached.

  The sheet stacking plate 28 on which the sheets 18 (see FIG. 1) are stacked has the cassette base 25 on the downstream side in the sheet feeding direction (in the direction of arrow B in FIG. 2) with the left and right (both ends in the direction of arrow AA ′) pivots. On the other hand, it can be moved up and down. In addition, a pair of width alignment cursors 37 a and 37 b for positioning the paper 18 loaded on the paper stacking plate 28 in the width direction are provided in guide grooves formed in the cassette base 25 on both sides of the paper stacking plate 28 in the width direction. Along the sheet width direction (in the direction of the arrow AA 'in the figure), each is provided so as to be reciprocally movable.

  Further, since the paper is sent in the direction of arrow B toward the paper transport path 11 (see FIG. 1), the rear end cursor 31 for aligning the rear end of the paper 18 is along a guide groove formed in the cassette base 25. It is provided so as to be able to reciprocate in parallel with the paper transport direction (the direction of arrow B in the figure). By moving the width alignment cursors 37a and 37b and the rear end cursor 31 in accordance with the size of the stacked paper, the paper 18 is stored in a predetermined position in the paper feed cassette 10.

  Guide rails 40a and 40b are attached to the outside of the wall portions 25a and 25d parallel to the insertion or withdrawal direction (arrow AA 'direction) of the paper feed cassette 10. The image forming apparatus 100 main body side (housing 100a side) is provided with a support portion (not shown) that slidably supports the guide rails 40a and 40b. The guide rails 40a and 40b are slid along the support portion. By moving it, the paper feed cassette 10 can be inserted into and pulled out of the housing 100a.

  Next, the unit drawing-in device 50 for assisting the insertion operation of the paper feed cassette 10 will be described. FIG. 4 is a perspective view showing the unit drawing-in device 50 mounted on the image forming apparatus 100 of the present embodiment. For convenience of explanation, the cover of the housing 51 is removed in FIG. 4 so that the internal structure can be seen.

  As shown in FIG. 4, the unit drawing device 50 has a function of drawing the paper feed cassette 10 to a predetermined position (paper feed position) in the image forming apparatus 100, and a first gear is provided on the bottom surface of the housing 51. 53, a second gear 55, an idle gear 57, a two-stage gear 59, a rotary damper 60, a damper holder 65, and the like are disposed.

  A guide groove 51a is formed on the bottom surface of the housing 51 along the insertion and withdrawal direction of the paper feed cassette 10 (the direction of the arrow AA ′ in FIG. 3). Engaging protrusions 80 (see FIG. 5) formed on the paper feed cassette 10 engage with the guide groove 51a, and slide along the guide groove 51a as the paper feed cassette 10 is inserted or pulled out. On the side surface of the housing 51, an opening 51b for guiding the engaging protrusion 80 to the guide groove 51a is formed.

  The first gear 53 and the second gear 55 are fan-shaped gears that are rotatably supported on the bottom surface of the housing 51 at the first rotation fulcrum 53a and the second rotation fulcrum 55a, respectively. The idle gear 57 meshes with the second gear 55 and the first gear 53 so that the rotation directions of the second gear 55 and the first gear 53 are the same.

  The first gear 53 is engaged with the small diameter portion of the two-stage gear 59, and the rotary damper 60 is engaged with the large diameter portion of the two-stage gear 59. The rotary damper 60 generates a large load (damping force) when the rotation speed is high, and generates a small load when the rotation speed is low. Then, this load is transmitted to the two-stage gear 59 as a braking force.

  The two-stage gear 59 is a one-way gear that can transmit a rotational driving force only in one direction. The small-diameter portion and the large-diameter portion of the two-stage gear 59 are connected via a one-way mechanism, and the one-way mechanism meshes in only one direction, so that the one-way between the first gear 53 and the two-stage gear 59 is achieved. The first gear 53 and the two-stage gear 59 are rotated in synchronization with each other. As the one-way mechanism, a one-way clutch, a latch, a ratchet or the like is used.

  Specifically, when the paper feed cassette 10 is pulled into the image forming apparatus 100, the first gear 53 rotates counterclockwise in FIG. 4 and the one-way between the first gear 53 and the two-stage gear 59. A rotational driving force is transmitted through the mechanism. On the other hand, when the paper feeding cassette 10 is pulled out from the image forming apparatus 100, the transmission of the rotational driving force between the first gear 53 and the two-stage gear 59 is interrupted by the one-way mechanism, so that the load by the rotary damper 60 is reduced. Is not transmitted from the two-stage gear 59 to the first gear 53.

  An arm member 61 is fixed to the first gear 53. The arm member 61 can rotate together with the first gear 53 with the first rotation fulcrum 53 a of the first gear 53 as a fulcrum. A hook member 63 that is rotatable with respect to the arm member 61 about the rotation fulcrum 61b is connected to the rotation end of the arm member 61.

  The hook member 63 does not engage the first engagement groove 63a used in the normal pull-in operation, the unit pull-in device 50, and the engagement protrusion 80 of the paper feed cassette 10, and the unit pull-in device 50 is in the pull-in completed state. The second engagement groove 63b used in the return operation when it becomes, and the latch that regulates the rotation of the arm member 61 by engaging the claw portion 65a of the damper holder 65 and restricting the movement of the hook member 63 A portion 63c is formed.

  One end of the tension spring 70 is engaged with the engagement hole 61 a of the arm member 61, and the other end of the tension spring 70 is engaged with the boss portion 55 b of the second gear 55. Accordingly, the arm member 61 is urged counterclockwise by the tension spring 70 with the first rotation fulcrum 53a as a fulcrum.

  Next, the drawing operation of the sheet feeding cassette 10 by the unit drawing device 50 will be described with reference to FIGS. FIG. 5 is a plan view schematically showing the state of the unit drawing-in device 50 before the paper feed cassette 10 is inserted (before the drawing is started). In the state shown in FIG. 5, the locking portion 63c of the hook member 63 is engaged with the claw portion 65a, and the hook member 63 is held at the open end (retraction start position) of the guide groove 51a. Further, the tension spring 70 is extended from the natural length, and an urging force (retraction force) is accumulated.

  When a predetermined amount of the paper cassette 10 is inserted into the main body of the image forming apparatus 100, as shown in FIG. 6, the engaging protrusions 80 provided on the paper cassette 10 are inserted into the guide groove 51a from the opening 51b of the housing 51, The inner surface (upper side surface of FIG. 6) of the first engagement groove 63a of the hook member 63 is pressed. As a result, the hook member 63 rotates counterclockwise about the fulcrum 61b, and the engagement state between the claw portion 65a and the locking portion 63c is released. When the engagement is released, the urging force of the tension spring 70 is released, whereby the inner surface (the lower surface in FIG. 6) of the first engagement groove 63a of the hook member 63 presses the engagement protrusion 80, and the paper is fed. Pull-in of the cassette 10 is started.

  Further, the urging force F acting on the engagement hole 61a of the arm member 61 from the tension spring 70 is engaged with the tangential component force F1 of the rotation path O (indicated by a broken-line arc in the drawing) of the engagement hole 61a. It is decomposed into a component force F2 from the hole 61a toward the rotation fulcrum (first rotation fulcrum 53a) of the arm member 61. The component force F <b> 1 is a rotational moment that rotates the arm member 61, and acts as a pulling force of the sheet cassette 10. In the state of FIG. 6, the direction of the urging force F is close to the direction of the component force F2, and the component force F1 is smaller than the component force F2.

  In the state of FIG. 7 in which the paper cassette 10 is further retracted from the state of FIG. 6, the arm member 61 and the first gear 53 are rotated counterclockwise about the first rotation fulcrum 53a by the urging force of the tension spring 70. Rotate. Then, one end (engagement hole 61 a) of the tension spring 70 moves on the rotation track O in the counterclockwise direction by the rotation of the arm member 61.

  At this time, the second gear 55 that meshes with the first gear via the idle gear 57 also rotates counterclockwise around the second rotation fulcrum 55a. That is, the boss portion 55b with which the other end of the tension spring 70 is locked rotates in the same direction as the engagement hole 61a with which one end of the tension spring 70 is locked.

  That is, as the arm member 61 rotates, one end (engagement hole 61a) of the tension spring 70 rotates in a direction approaching the other end (boss portion 55b) of the tension spring 70, and the tension spring 70 contracts. Although the magnitude of the force F becomes smaller, the boss portion 55b also rotates in a direction away from the engagement hole 61a, so that the attenuation of the bias force F due to the contraction of the tension spring 70 can be suppressed. As a result, the magnitude of the biasing force F is slightly smaller than that in FIG. Further, the direction of the urging force F changes in a direction away from the direction of the component force F2, and approaches the direction of the component force F1, so that the ratio of the component force F1 is larger than that in FIG.

  In the state of FIG. 8 in which the paper cassette 10 is further pulled from the state of FIG. 7, one end and the other end of the tension spring 70 are further moved in the counterclockwise direction. The magnitude of the urging force F is reduced by the contraction of the tension spring 70 accompanying the rotation of the arm member 61, but the attenuation of the urging force F is suppressed by the rotation in the direction away from the engagement hole 61a of the boss portion 55b. Therefore, the magnitude of the biasing force F is slightly smaller than that in FIG. Further, since the direction of the urging force F is closer to the direction of the component force F1, the ratio of the component force F1 is larger than that in FIG.

  As shown in FIG. 9, when the engagement protrusion 80 moves to the end point of the guide groove 51 a, the paper feed cassette 10 is drawn to a paper feedable position (drawing completion position) in the image forming apparatus 100. Here, the paper feedable position is defined by the contact between the engagement protrusion 80 and the end point of the guide groove 51a. For example, before the engagement protrusion 80 reaches the end point of the guide groove 51a, the paper feed cassette 10 side is provided. The abuttable piece can be abutted against the abutted surface on the image forming apparatus 100 main body side, so that the feedable position can be defined.

  Further, during the pull-in operation of the paper feed cassette 10, the load (torque) of the rotary damper 60 acts on the first gear 53 via the two-stage gear 59. For example, when the amount of paper stored in the paper feed cassette 10 is small and the pull-in load of the paper feed cassette 10 is small and the pull-in speed by the component force F1 is large, the torque of the rotary damper 60 becomes large and the paper feed The pull-in speed of the cassette 10 can be reduced. Further, when a large amount of paper is stored in the paper feed cassette 10 and the pull-in load of the paper feed cassette 10 is large, the torque of the rotary damper 60 becomes small and the paper feed cassette 10 cannot be pulled in with the component force F1. Can be suppressed.

  On the other hand, when the paper cassette 10 is pulled out from the state shown in FIG. 9, the engagement protrusion 80 presses the inner surface (the lower surface in FIG. 9) of the first engagement groove 63a. As a result, the arm member 61 rotates in the clockwise direction against the urging force F of the tension spring 70, and in reverse order from the retracting operation, the states shown in FIGS. 8 to 6 are sequentially passed as shown in FIG. 5. After the engaging portion 63c engages with the claw portion 65a and the hook member 63 is returned to the starting position, the engaging projection 80 is detached from the guide groove 51a, and the operation of pulling out the sheet feeding cassette 10 is completed.

  When the paper cassette 10 is pulled out from the image forming apparatus 100, the transmission of the rotational driving force between the first gear 53 and the second gear 59 is blocked by the second gear 59 that is a one-way gear. The load of the rotary damper 60 is not transmitted to the first gear 53 and the arm member 61. Therefore, the sheet feeding cassette 10 can be pulled out smoothly without receiving the load of the rotary damper 60.

  By the way, when the engaging portion 63c and the claw portion 65a are disengaged by some external force before the sheet feeding cassette 10 is inserted, the unit retracting device 50 is in the retracted state as shown in FIG. Although the engagement protrusion 80 and the hook member 63 (first engagement groove 63a) are not engaged with each other, the engagement protrusion 80 and the hook member 63 (first engagement groove 63a) are not engaged. The return from the engagement abnormality is performed by the second engagement groove 63b and the guide groove 63d communicating with the second engagement groove 63b from the upstream end in the rotation direction of the hook member 63.

  Specifically, when the paper feed cassette 10 is inserted into the image forming apparatus 100 in the state shown in FIG. 10 in the normal operation, the engagement protrusion 80 passes from the guide groove 51a through the guide groove 63d to pass through the second engagement groove. 63b is inserted. When the sheet cassette 10 is pulled out in this state, the engagement protrusion 80 presses the inner surface (the lower surface in FIG. 10) of the second engagement groove 63b, and the arm member 61 resists the urging force F of the tension spring 70. Rotate clockwise. Thereafter, the locking portion 63c engages with the claw portion 65a of the damper holder 65, and the hook member 63 returns to the pull-in start position, and the unit pull-in device 50 is inserted before the paper feed cassette 10 shown in FIG. ) Can be restored.

  According to the unit pull-in device 50 of the present embodiment, the arm member 61 (and the first gear 53) in which one end of the tension spring 70 is locked, and the second gear 55 in which the other end of the tension spring 70 is locked. Are rotated in the same direction, the damping of the urging force F of the tension spring 70 accompanying the rotation of the arm member 61 is suppressed. Accordingly, a certain pulling force can be ensured from the start of pulling in the paper cassette 10 to the completion of pulling, and the pulling operation can be performed smoothly.

  Further, since a predetermined urging force is applied to the hook member 63 even when the pull-in is completed, the engagement protrusion 80 can be reliably left at the end point of the guide groove 51a, and the paper feed cassette 10 is placed in the image forming apparatus 100. Can be stably mounted at the paper feedable position.

  Further, since the rotational moment (component force F1) for rotating the arm member 61 changes from the start of the pull-in of the paper cassette 10 to the completion of the pull-in, the first gear 53 and the second gear 55 are changed. The pulling force of the paper feeding cassette 10 can be further strengthened together with the effect of suppressing the attenuation of the biasing force F by the rotation in the same direction.

  Further, by connecting the rotary damper 60 to the first gear 53 to which the arm member 61 is fixed, the image forming apparatus can always pull the paper feed cassette 10 at a constant drawing speed regardless of the amount of paper in the paper feed cassette 10. 100 can be pulled into.

  In addition, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the meaning of this invention. For example, in the above embodiment, the first gear 53 to which the arm member 61 to which one end of the tension spring 70 is locked is fixed, and the second gear 55 to be provided with the boss portion 55b to which the other end of the tension spring 70 is locked. Are connected via an idle gear 57, and the first gear 53 and the second gear 55 rotate in the same direction. However, instead of the connection by the idle gear 57, the first gear 53 and the second gear 55 are connected. The gear 55 may be connected by a link mechanism that rotates simultaneously and in the same direction.

  In the above-described embodiment, the unit drawing device 50 that pulls the paper feed cassette 10 into the main body of the image forming apparatus 100 has been described. However, the developing device 4 and the fixing device 9 are not limited to the paper feed cassette 10 and the main body of the image forming apparatus 100. In the case where it can be inserted into or pulled out from the inside, it can be applied in the same manner as a drawing-in device for those units.

  Further, the present invention is not limited to the monochrome multifunction device as shown in FIG. 1, but can be pulled out to a color printer, a color multifunction device, a monochrome printer, a color multifunction device having an image forming unit of an inkjet recording method, a color printer, or the like. The present invention can also be applied to other image forming apparatuses provided with a unit.

  INDUSTRIAL APPLICABILITY The present invention can be used for a drawing device that draws a unit that can be pulled out and inserted into the device body into the device body. By using the present invention, it is possible to provide a unit retracting device that can reliably retract a unit to a predetermined position in the apparatus main body without applying a load to the user with a simple configuration.

10 Paper cassette (recording medium storage cassette)
12 Paper feed unit 18 Paper (recording medium)
50 Unit Pull-In Device 51 Housing 51a Guide Groove 51b Opening 53 First Gear (First Rotating Member)
53a Center of rotation (first pivot point)
55 Second gear (second rotating member)
55a Center of rotation (second pivot point)
55b Boss part 57 Idle gear 59 Two-stage gear (one-way gear)
60 Rotary damper (suppressing member)
61 Arm member (first rotating member)
61a engagement hole 61b fulcrum 63 hook member 63a first engagement groove 63b second engagement groove 63c locking portion 63d guide groove 65 damper holder 65a claw portion 70 tension spring (biasing member)
80 Engaging protrusion (engaged part)
100 Image forming apparatus

Claims (7)

A hook member that engages an engaged portion provided in a unit that can be inserted into or pulled out from the apparatus main body;
When the hook member and the engaged portion are engaged at the pull-in start position of the unit , a pull-in force generating mechanism that applies a pull-in force to the unit ;
A unit drawing device for drawing the unit to a drawing completion position in the device body,
The pulling force generating mechanism is
A first rotation member that is rotatably provided at a first rotation fulcrum and has the hook member connected to an end portion on the rotation side, and one end locked to the first rotation member . An urging member that urges the rotating member in a direction in which the hook member pulls the unit into the apparatus main body, and the other end of the urging member are locked, so that the second fulcrum can be rotated. A second rotating member provided,
The second rotating member rotates in the same direction as the first rotating member with the rotation of the first rotating member by the urging force of the urging member,
The first rotating member includes an arm member to which the hook member is rotatably connected, and a first gear to which the arm member is fixed and rotatable about the first rotation fulcrum. The unit retraction device, wherein the second rotating member is a second gear connected to the first gear via one or more idle gears.   2. The biasing direction of the biasing member changes in a direction in which a rotational moment acting on the first rotating member increases from the start of pulling of the unit to the completion of pulling. Unit retractor. When the unit is pulled inward of the apparatus main body by the biasing force generated by the biasing member and is capable of transmitting power to the first gear, the first rotating member rotates, A suppression member that suppresses the rotation of the arm member by generating a load corresponding to the rotation speed of the first gear over the entire region from the pull-in start position to the pull-in completion position is provided. The unit drawing-in apparatus of Claim 1 or Claim 2. A one-way gear is provided between the first gear and the restraining member, which can transmit a drive to and from the first gear only when the unit is pulled into the apparatus main body. Item 4. The unit retractor according to Item 3. The hook member is rotatably connected to the arm member, and engages with a first engagement groove that engages with the engaged portion, and a claw provided near the pull-in start position. And has a locking part,
The engaged portion engaged with the hook member presses the hook member and the hook member rotates, whereby the engagement between the claw portion and the locking portion is released. unit retraction device according to any one of claims 1 to 4. The unit drawing-in device according to claim 1 , wherein the unit is a recording medium storage cassette that stores a recording medium . An image forming apparatus comprising the unit drawing-in device according to claim 1 .