JP2016014817A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that can simultaneously drive a developing part and a separation mechanism of a fixing part, and simplify control.SOLUTION: After a motor 400 is reversely rotated, when an electromagnetic clutch 410 is energized, driving force of the motor 400 is transmitted to a second drive gear mechanism 603 and a third drive gear mechanism 604. When a first cam gear 513 included in the second drive gear mechanism 603 rotates clockwise and a first cam 250 moves backward, the mode of arrangement of developing rollers 110 is switched to a non-supply mode. When a second cam gear 517 included in the third drive gear mechanism 604 rotates counterclockwise together with the backward movement of the first cam 250 and a second cam 301 moves forward to a predetermined position, pressure contact with a first roller 81 and a second roller 82 is released.

Description

  The present invention relates to an image forming apparatus.

  There is known an image forming apparatus that separates a fixing unit at the same time as a developing unit is separated from a photosensitive member when an image forming unit that forms an image on a sheet does not form an image on a sheet.

  For example, the image forming apparatus described in Patent Document 1 separates the developing roller from the photosensitive member and simultaneously separates the pressure roller from the heating roller based on control by the control unit.

JP 2003-348280 A

  However, in the above image forming apparatus, when the separation mechanism of the developing unit and the separation mechanism of the fixing unit are driven at the same time, the control unit needs to control the separation mechanisms of the developing unit and the fixing unit. There was a problem that the control of was complicated.

  The present invention has been made to solve the above problems, and provides an image forming apparatus capable of simplifying control while simultaneously driving the separation mechanism of the developing unit and the separation mechanism of the fixing unit. The purpose is to provide.

  In order to achieve the above object, an image forming apparatus of the present invention is driven by a photosensitive member, a developing unit that develops an electrostatic latent image formed on the photosensitive member, a motor, and a driving force from the motor. A displacement mechanism for displacing the developing unit between a developing position for developing the electrostatic latent image and a non-developing position for developing the electrostatic latent image, and transferring the developer image developed by the developing unit to a recording medium. A transfer unit, a first transport member that transports the recording medium on which the developer image has been transferred by the transfer unit, and a second transport member that forms a nip portion that sandwiches the recording medium between the first transport member, A pressure contact mechanism that presses any one of the first transport member and the second transport member against the other transport member, and is driven by the driving force of the motor so that the one transport member is separated from the other transport member. Displace and change the pressure of the nip A contact force changing mechanism, characterized the interlocking mechanism for connecting the displacement mechanism and the pressing force adjusting mechanism interlocking the displacement mechanism and the pressing force adjusting mechanism, and a control unit for controlling the motor, in that it comprises.

  In the image forming apparatus, the displacement mechanism may be configured by a first cam having a first cam portion that is a cam surface extending in a direction intersecting with a straight line connecting the developing position and the non-developing position.

  In the image forming apparatus, the first cam may have a first rack gear, and the interlocking mechanism may have a first cam gear that meshes with the first rack gear.

  In the image forming apparatus, the pressing force changing mechanism may be configured by a second cam having a second cam portion that is a cam surface extending in a direction intersecting a pressing direction of the pressing mechanism.

  In the image forming apparatus, the second cam may have a second rack gear, and the interlocking mechanism may have a second cam gear that meshes with the second rack gear.

  In the image forming apparatus, a plurality of photoconductors are provided, a developing unit is provided for each of the plurality of photoconductors, and the pressure contact force changing mechanism is such that the displacement mechanism has any one of the plurality of developing units at the developing position. In the displaced state, a configuration in which one of the conveying members is displaced in a separating direction may be maintained.

  In the image forming apparatus, the interlocking mechanism and the one conveying member may be driven by a motor.

  In the image forming apparatus, the first conveying member may be a cylindrical fixing film, and the second conveying member may be a pressure roller that sandwiches the fixing film.

  According to the present invention, the displacement mechanism and the pressing force changing mechanism are connected by the interlocking mechanism, and the displacement mechanism and the pressing force changing mechanism are interlocked. Therefore, the control device controls the displacement mechanism and the pressing force changing mechanism separately. Since the displacement mechanism and the pressure contact force changing mechanism can be interlocked by simply controlling the interlocking mechanism, the control of the control device is simplified while simultaneously driving the displacement mechanism and the pressure contact force changing mechanism. can do.

1 is a schematic cross-sectional view illustrating a configuration of an image forming apparatus according to an embodiment. It is a front perspective view which shows the structure of a displacement mechanism and a pressing force change mechanism. It is a back perspective view which shows the structure of a displacement mechanism and a pressing force change mechanism. It is explanatory drawing explaining operation | movement of a press-contact force change mechanism. It is sectional drawing which shows the state by which the developing roller has been arrange | positioned in the image development position. It is sectional drawing which shows the state by which the developing roller is arrange | positioned in the non-developing position. It is explanatory drawing explaining the relationship between a 1st inclined surface and a 1st separation lever. It is explanatory drawing explaining the relationship between a 2nd inclined surface and a 2nd separation lever. It is a front view explaining the structure of an interlocking mechanism. It is explanatory drawing which shows an example of the fixing device in other embodiment.

  Embodiments for carrying out the present invention will be described in detail with reference to the drawings. After describing the overall configuration of the image forming apparatus 1, features of the present invention will be described. The directions in the following description will be described with reference to the user when using the image forming apparatus 1. Specifically, in FIG. 1, the left side “front”, the right side “rear”, the upper side “up”, and the lower side “lower” as viewed in the drawing. Also, the front side of the page is “right” and the back side is “left”.

  FIG. 1 is a schematic cross-sectional view illustrating an example of an image forming apparatus according to an embodiment of the present invention. As shown in FIG. 1, the image forming apparatus 1 includes a housing 10 that is formed in a substantially rectangular shape, and a paper feeding unit 20 that feeds paper P as an example of a recording medium such as a recording paper or an OHP sheet. The image forming unit 30 forms an image on the fed paper P, and the paper discharge unit 90 discharges the paper P on which the image is formed to the outside of the housing 10.

  A front cover 11 is provided on the front surface of the housing 10. The front cover 11 is supported by the housing 10 so as to be openable and closable with respect to the housing 10.

  The paper feed unit 20 is disposed at the lower part of the housing 10, and includes a paper feed tray 21 that holds the paper P and a transport device 22 that transports the paper P held in the paper feed tray 21 to the image forming unit 30. And.

  The image forming unit 30 includes a process unit 40, a scanner unit 60, a transfer unit 70, and a fixing device 80.

  The process unit 40 includes a drawer 50 and four developing cartridges 100 that are detachably attached to the drawer 50.

  The drawer 50 can be inserted into and removed from the housing 10 with the front cover 11 open. The drawer 50 includes four photosensitive drums 61 as an example of a photosensitive member and a known charger (not shown). Yes.

  The developing cartridge 100 includes a developing roller 110 as an example of a developing unit that develops an electrostatic latent image formed on the photosensitive drum, and supplies toner to a well-known toner storage chamber (not shown) and each developing roller 110. Supply roller or the like.

  Each developing roller 110 is in contact with the corresponding photosensitive drum 61 to develop an electrostatic latent image on the photosensitive drum 61, and is separated from the photosensitive drum 61 to electrostatic latent image on the photosensitive drum 61. The image can be displaced to a non-development position where the image is not developed.

  The scanner unit 60 is disposed in the upper part of the housing 10 and includes a laser light emitting unit (not shown), a polygon mirror, a lens, a reflecting mirror, and the like.

  The transfer unit 70 is disposed at the center of the housing 10 and includes a drive roller 71, a driven roller 72, a conveyance belt 73, and four transfer rollers 74. The conveyor belt 73 is stretched between the driving roller 71 and the driven roller 72. The outer surface of the conveyance belt 73 is in contact with the four photosensitive drums 61. Four transfer rollers 74 are disposed inside the conveyor belt 73. Each transfer roller 74 is disposed to face the photosensitive drum 61.

  When the paper P is transported to the image forming unit 30 by the transport device 22, an image is formed on the paper P. In the image forming unit 30, the surface of each photosensitive drum 61 is first uniformly charged by a charger and then exposed by the scanner unit 60. As a result, the potential of the exposed portion on the surface of each photosensitive drum 61 is lowered, and an electrostatic latent image based on the image data is formed on each photosensitive drum 61.

  Next, the developing roller 110 supplies toner to the electrostatic latent image on each photosensitive drum 61 and develops the electrostatic latent image on each photosensitive drum 61.

  Thereafter, the paper P is supplied onto the conveyance belt 73 and passes between the photosensitive drums 61 and the transfer rollers 74, whereby toner as an example of a developer image developed on the photosensitive drums 61. The image is transferred onto the paper P by each transfer roller 74. At this time, a transfer bias is applied to the transfer roller 74 by constant current control.

  The transferred paper P is conveyed toward the fixing device 80. The fixing device 80 is provided opposite to the first roller 81 as an example of a first conveying member that is heated by a heat source (not shown) and conveys the paper P, and between the first roller 81 and the first roller 81. And a second roller 82 as an example of a second transport member that forms a nip portion that sandwiches the paper P.

  In the present embodiment, the fixing device 80 includes a first roller 81 and a second roller 82. However, the present invention is not limited to this, and as shown in FIG. 10, the fixing device 80 is in sliding contact with the cylindrical fixing film 110, the halogen lamp 120 disposed inside the fixing film 110, and the inner surface of the fixing film 110. The fixing film 110 is sandwiched between the nip plate 130, the reflection plate 140 that reflects the radiant heat from the halogen lamp 120 toward the nip plate 130, and the fixing film 110. It may be a fixing device that employs a film fixing system that includes a pressure roller 150 that forms a nip portion, and stays 160 that support both ends of the nip plate 130 in the conveyance direction of the paper P.

  The transferred paper P is conveyed to the fixing device 80 and passes between the first roller 81 and the second roller 82, whereby the toner image transferred onto the paper P is thermally fixed.

  Then, the heat-fixed paper P is discharged out of the housing 10 by a paper discharge unit 90 including a plurality of transport rollers 91.

  FIG. 2 is a front perspective view illustrating the configuration of the displacement mechanism 200 and the pressure contact force changing mechanism 300. As shown in FIG. 2, the first roller 81 is formed in a columnar shape extending in the left-right direction. The second roller 82 is disposed at a position facing the first roller 81 and is formed in a columnar shape extending in the left-right direction.

  A pressure contact force changing mechanism 300 that changes the pressure contact force of the nip portion is provided at both ends of the second roller 82 in the left-right direction. A displacement mechanism 200 is provided for displacement between the two.

  Hereinafter, the configuration and operation of the pressure contact force changing mechanism 300 will be described in detail. The pressure contact force changing mechanism 300 is a first connection that connects two second cams 301 extending in the front-rear direction at both ends in the left-right direction of the second roller 82, and the second cam 301A on the left side and the second cam 301B on the right side. And a pressure contact mechanism 85 that presses the second roller 82 against the first roller 81. The pressure contact mechanism 85 presses the second roller 82 in a substantially vertical direction.

  In this embodiment, the pressing mechanism 85 presses the second roller 82 against the first roller 81, but is not limited thereto, and may be configured to press the first roller 81 against the second roller 82.

  The second cam 301 is supported by the housing 10 so as to be movable in the front-rear direction. A second rack gear 302 extending in the front-rear direction is formed on the upper surface of each second cam 301.

  The second rack gear 302 has a plurality of gear teeth arranged in the front-rear direction. The driving force of the motor 400 is transmitted to the second rack gear 302A on the left side through an interlocking mechanism 600 composed of a plurality of gears. The motor 400 is controlled by the control device 450 and can rotate forward and backward.

  The control device 450 includes a CPU, a RAM, a ROM, and an input / output circuit, and executes control by performing each arithmetic processing based on programs, data, and the like stored in the ROM.

  The first connecting portion 310 includes a first shaft 308 extending in the left-right direction and two first pinion gears 309 provided at both ends in the left-right direction of the first shaft 308.

  The left first pinion gear 309A transmits the driving force of the motor 400 transmitted to the left second rack gear 302A to the right second rack gear 302B via the first shaft 308.

  FIG. 3 is a rear perspective view showing configurations of the displacement mechanism 200 and the pressure contact force changing mechanism 300. As shown in FIG. 3, a first drive gear 608 for driving the first roller 81 is inserted into the left end portion of the first roller 81. The first drive gear 608 is connected to the interlocking mechanism 600. The driving force of the motor 400 is transmitted to the first driving gear 608 via the interlocking mechanism 600 to rotate the first roller 81.

  In the present embodiment, the first drive gear 608 is inserted into the first roller 81, but the present invention is not limited to this, and the first drive gear 608 may be inserted into the second roller 82.

  A pressure contact mechanism 85 is provided at both left and right ends of the second roller 82. The pressure contact mechanism 85 includes a pressure contact member 86 that presses the second roller 82 against the first roller 81, and a spring member 87 that biases the pressure contact member 86 substantially upward.

  The second roller 82 has convex portions 83 that protrude in the left-right direction from both ends in the left-right direction of the second roller 82. The convex portion 83 is supported by the press contact member 86 and urged substantially upward.

  A bearing 84 that covers the outer peripheral surface of the projection 83 is provided at the tip of the projection 83. The convex portion 83 and the bearing 84 are inserted into a guide portion 303 as an example of a second cam portion formed on the second cam 301.

  The guide portion 303 is a cam surface formed so as to penetrate the second cam 301 in the left-right direction, and is formed in a step shape extending in the front-rear direction. The guide portion 303 has a first cam surface 304, a second cam surface 305, a third cam surface 306, and a fourth cam surface 307.

  The first cam surface 304 is formed to extend in a direction substantially perpendicular to the pressure contact direction of the pressure contact mechanism 85. The second cam surface 305 is formed in parallel with the first cam surface 304 below and behind the first cam surface 304.

  A first curved surface portion 401 is formed between the first cam surface 304 and the second cam surface 305 in the guide portion 303. The first curved surface portion 401 connects the first cam surface 304 and the second cam surface 305 with a smooth curved surface.

  The third cam surface 306 is formed in parallel with the second cam surface 305 below and behind the second cam surface 305. A second curved surface portion 402 is formed between the second cam surface 305 and the third cam surface 306 in the guide portion 303. The second curved surface portion 402 connects the second guide portion 305 and the third cam surface 306 with a smooth curved surface.

  The fourth cam surface 307 is formed in parallel with the first cam surface 304 below and in front of the first cam surface 304. A third curved surface portion 403 is formed between the first cam surface 304 and the fourth cam surface 307 in the guide portion 303. The third curved surface portion 403 connects the first cam surface 304 and the fourth cam surface 307 with a smooth curved surface.

  Here, the second cam surface 305 and the fourth cam surface 307 are formed at the same height in the vertical direction.

  The second cam surface to the fourth cam surfaces 305, 306, and 307 are in contact with the upper surface of the bearing 84 and push down the convex portion 83 and the bearing 84 against the urging force of the spring member 87. As a result, the second roller 82 is displaced in a direction away from the first roller 81, and the pressure contact force at the nip portion formed by the first roller 81 and the second roller 82 is changed.

  Here, the second cam surface to the fourth cam surfaces 305, 306, 307 are formed to extend in parallel to the first cam surface 304, in other words, in a direction substantially orthogonal to the pressure contact direction of the pressure contact mechanism 85. It can suppress that the convex part 83 and the bearing 84 move on the guide part 303 by 85 press-contact force. That is, the positioning accuracy of the second roller 82 can be improved.

  When the convex portion 83 is disposed below the first cam surface 304 and the bearing 84 contacts the first cam surface 304, the pressure roller 82 is disposed at the first position, and the nip portion is moved by the first pressure contact force. Is formed.

  A second cam gear 517 that meshes with the second rack gear 302A is provided above the left second rack gear 302A. The second cam gear 517 is rotatable according to the forward rotation and reverse rotation of the motor 400. Here, the forward rotation means that the interlocking mechanism 600 is rotated clockwise as viewed from the front as shown in FIG. 2, and the reverse rotation is that the interlocking mechanism 600 is rotated counterclockwise when viewed from the front. Say.

  When the controller 450 rotates the motor 400 in the reverse direction, the driving force of the motor 400 is transmitted to the second cam gear 517, the second cam gear 517 rotates and the driving force is transmitted to the left second rack gear 302A, and the left The two cams 301A move forward.

  In conjunction with the left second cam 301A moving forward, the left first pinion gear 309A rotates and transmits a driving force to the right first pinion gear 309B via the first shaft 308. As a result, the second cam 301 is movable.

  When the driving force due to the reverse rotation of the motor 400 is transmitted to the second rack gear 302 and the second cam 301 moves forward, the bearing 84 that is in contact with the first cam surface 304 is in contact with the first cam surface 304 as shown in FIG. After sliding on the first cam surface 304 and sliding on the first curved surface portion 401, the first cam surface 304 comes into contact with the second cam surface 305 as shown in FIG.

  At this time, the convex portion 83 and the bearing 84 are pushed down below the first cam surface 304 against the urging force of the spring member 87 by the second cam surface 305. In this way, the second roller 82 is pushed downward by the second cam surface 305 and is displaced to the third position, which is a position displaced in a direction away from the first roller 81 from the first position. As a result, the second roller 82 is pressed against the first roller 81 with a third pressing force that is a pressing force that is weaker than the first pressing force, and a nip portion is formed with the third pressing force.

  When the second cam 301 moves further forward, the bearing 84 in contact with the second cam surface 305 slides on the second cam surface 305 and slides the second curved surface portion 402 as shown in FIG. After moving, it abuts against the third cam surface 306 as shown in FIG.

  At this time, the convex portion 83 and the bearing 84 are pushed down below the second cam surface 305 by the third cam surface 306 against the urging force of the spring member 87. Thus, the second roller 82 is pushed downward by the third cam surface 306 and is displaced to the second position, which is a position displaced in the direction away from the first roller 81 from the first position and the third position. The As a result, the second roller 82 is pressed against the first roller 81 with a second pressing force that is weaker than the first pressing force and the third pressing force, and the nip portion is pressed with the second pressing force. It is formed.

  Here, the second pressure contact force is zero. That is, the pressure contact between the first roller 81 and the second roller 82 is released, and the first roller 81 and the second roller 82 are separated from each other.

  In this embodiment, the second pressure contact force is set to zero and the first roller 81 and the second roller 82 are separated from each other. However, the present invention is not limited to this, and the second pressure contact force is an arbitrary pressure contact force. The configuration may be such that the first roller 81 and the second roller 82 are in pressure contact.

  Further, when the driving force due to the forward rotation of the motor 400 is transmitted to the second rack gear 302 and the second cam 301 moves rearward, as shown in FIG. 4A, a bearing 84 that is in contact with the first cam surface 304 is obtained. Slides on the first cam surface 304, slides on the third curved surface portion 403, and then contacts the fourth cam surface 307 as shown in FIG.

  At this time, the convex portion 83 and the bearing 84 are pushed downward from the first cam surface 304 against the urging force of the spring member 87 by the fourth cam surface 307. As a result, the second roller 82 is pressed against the first roller 81 with the third pressing force, and a nip portion is formed with the third pressing force.

  Next, the configuration and operation of the displacement mechanism 200 will be described in detail. FIG. 5 is an explanatory diagram showing a state when the developing roller 110 is disposed at the developing position. As shown in FIG. 5, the drawer 50 is provided with a plurality of pressing members 63 provided rotatably on the drawer 50. The pressing member 63 is urged clockwise by a torsion spring (not shown).

  The plurality of pressing members 63 urge the protrusions 101 formed on the developing cartridge 100 toward the photosensitive drum 61. Thus, each developing roller 110 is urged toward the photosensitive drum 61 via the developing cartridge 100 by the plurality of pressing members 63 and is disposed at the developing position.

  The drawer 50 is provided with a separation lever 64 for separating the developing roller 110 from the photosensitive drum 61 corresponding to each developing cartridge 100.

  FIG. 6 is an explanatory diagram showing a state when the developing roller 110 is disposed at the non-developing position. As shown in FIG. 6, when the separation lever 64 is rotated clockwise in the drawing, the protrusion 101 is pressed obliquely upward by a pressing portion 641 formed on the separation lever 64. At this time, the pressing portion 641 presses the protrusion 101 against the urging force of the pressing member 63, so that the separation lever 64 receives the urging force of the pressing member 63.

  As a result, the developing roller 110 disposed at the developing position is separated from the photosensitive drum 61 in a direction crossing the front-rear direction and displaced to the non-developing position. Each separation lever 64 is actuated by the displacement mechanism 200.

  As shown in FIG. 2, the displacement mechanism 200 includes two first cams 250 extending in the front-rear direction, and a second connecting portion 205 that connects the left first cam 250A and the right first cam 250B. Yes.

  Each first cam 250 is supported by the housing 10 so as to be movable in the front-rear direction. A first rack gear 208 is formed on the side surface of the left first cam 250A so as to extend in the front-rear direction.

  The first rack gear 208 has a plurality of gear teeth arranged in the front-rear direction, and meshes with the first cam gear 513. The first cam gear 513 includes a seventh large-diameter gear 513A and a seventh small-diameter gear 513B that is provided on the right side of the seventh large-diameter gear 513A and has a smaller diameter than the seventh large-diameter gear 513A. The seventh large-diameter gear 513A and the seventh small-diameter gear 513B are integrally formed and are inserted through the same gear shaft.

  The second connecting portion 205 includes a second shaft 206 that extends in the left-right direction, and two second pinion gears 207 that are provided at both ends of the second shaft 206 in the left-right direction.

  On the upper surface of each first cam 250, a cam drive gear 209 that engages with each second pinion gear 207 is formed extending in the front-rear direction. The cam drive gear 209 has a plurality of gear teeth arranged in the front-rear direction.

  The left second pinion gear 207A transmits the driving force of the motor 400 transmitted to the first rack gear 208 to the right cam drive gear 209B via the second shaft 206 and the right second pinion gear 207B.

  The first cam 250 mainly includes a first inclined surface 201 and three second inclined surfaces 202.

  As shown in FIG. 3, the first inclined surface 201 is formed on the first cam 250 so as to be inclined with respect to the front-rear direction. The first inclined surface 201 is an inclined surface for separating the first developing roller 110A for monochrome among the four developing rollers 110 from the first photosensitive drum 61A corresponding to the first developing roller 110A.

  A first holding surface 203 as an example of the first cam portion is formed on the front side of the first inclined surface 201. The first holding surface 203 is a cam surface that extends continuously in parallel with the first inclined surface 201 in the front-rear direction, and maintains a state where the first developing roller 110A and the first photosensitive drum 61A are separated from each other.

  When the first cam 250 is moved rearward, as shown in FIGS. 7A to 7C, the first inclined surface 201 comes into contact with the first separation lever 64A corresponding to the first developing roller 110A, and The 1 separation lever 64A is pushed down in the clockwise direction in the figure.

  When the first separation lever 64A is pushed down to the first holding surface 203, the first holding surface 203 receives the urging force of the pressing member 63 applied to the first separation lever 64A, and the first separation lever 64A rotates clockwise in the figure. The depressed state is maintained. As a result, the first developing roller 110A arranged at the development position is displaced to the non-development position and held at the non-development position.

  On the other hand, when the first cam 250 is moved forward in the state of FIG. 7C, the first separation lever 64 </ b> A receiving the urging force of the pressing member 63 causes the first holding surface 203 and the first inclination. It slides along the surface 201, returns to the state of FIG. 7A, and the first developing roller 110A is displaced to the developing position.

  Further, as shown in FIG. 3, the second inclined surface 202 is formed on the first cam 250 so as to be inclined with respect to the front-rear direction. The second inclined surface 202 is an inclined surface for separating the color second developing roller 110B from the second photosensitive drum 61B corresponding to the second developing roller 110B.

  A second holding surface 204 as an example of a first cam portion is formed on the front side of the second inclined surface 202. The second holding surface 204 is a cam surface that extends continuously in parallel to the front-rear direction following the second inclined surface 202, and maintains a state where the second developing roller 110B and the second photosensitive drum 61B are separated from each other.

  When the first cam 250 is moved rearward, as shown in FIGS. 8A to 8C, the second inclined surface 202 comes into contact with the second separation lever 64B corresponding to the second developing roller 110B, and 2 Push down the separation lever 64B clockwise in the figure.

  When the second separation lever 64B is pushed down to the second holding surface 204, the second holding surface 204 receives the urging force of the pressing member 63 applied to the second separation lever 64B, and the second separation lever 64B rotates clockwise in the figure. The depressed state is maintained. As a result, the second developing roller 110B arranged at the development position is displaced to the non-development position and held at the non-development position.

  On the other hand, when the first cam 250 is moved forward in the state of FIG. 8C, the second separation lever 64 </ b> B receiving the urging force of the pressing member 63 causes the second holding surface 204 and the second inclined surface to move. It slides along the surface 202, returns to the state of FIG. 8A, and the second developing roller 110B is displaced to the developing position.

As shown in FIG. 3, the distance between a pair of adjacent second inclined surfaces 202 is the same distance, but the distance between the adjacent first inclined surface 201 and the second inclined surface 202 is a pair of distances. The distance between the second inclined surfaces 202 is different. Accordingly, since the plurality of separation levers 64 are arranged at the same pitch, the position of the first inclined surface 201 with respect to the first separation lever 64A is different from the position of the second inclined surface 202 with respect to the second separation lever 64B. Yes.

  Further, since each separation lever 64 is disposed at the same position with respect to the corresponding developing roller 110, the position of the first inclined surface 201 with respect to the first developing roller 110A and the second inclined surface 202 with respect to the second developing roller 110B. The position is different. As a result, as shown in FIGS. 7 and 8, the timing for operating the first separation lever 64A and the second separation lever 64B can be changed, and the mode of arrangement of the developing rollers 110 can be switched to three modes. It is possible.

  Specifically, by moving the first cam 250 in the front-rear direction, the arrangement mode of each developing roller 110 can be switched between a color mode, a monochrome mode, and a non-supply mode.

  As shown in FIGS. 7A and 8A, the color mode is a mode in which all the developing rollers 110 are arranged at the developing position. In the color mode, a color toner image is formed on the paper P.

  In the monochrome mode, as shown in FIGS. 7B and 8B, only the first development roller 110A for monochrome is disposed at the development position, and the second development roller 110B for color is disposed at the non-development position. Mode. In the monochrome mode, a monochrome toner image is formed on the paper P.

  The non-supply mode is a mode in which all the developing rollers 110 are arranged at the non-developing position, as shown in FIGS. 7C and 8C. In the non-supply mode, no toner image is formed on the paper P.

  Next, the configuration of the interlocking mechanism 600 will be described in detail. As shown in FIG. 9, the interlocking mechanism 600 includes a fixing driving gear mechanism 601, a first driving gear mechanism 602, a second driving gear mechanism 603, a third driving gear mechanism 604, and an electromagnetic clutch 410. A thick broken line shown in FIG. 9 represents a transmission path of the driving force of the motor 400.

  The fixing drive gear mechanism 601 is a gear train having a first gear 501, a second gear 503, a third gear 504, a swing gear 420, and a fourth gear 505.

  The first gear 501 includes a first large-diameter gear 501A and a first small-diameter gear 501B that is a gear having a smaller diameter than the first large-diameter gear 501A. The first large-diameter gear 501A and the first small-diameter gear 501B are integrally formed and are inserted through the same gear shaft.

  The first large-diameter gear 501A meshes with a drive gear (not shown) that rotates integrally with the rotation shaft of the motor 400. The first small diameter gear 501B meshes with a second gear 503 provided above the first small diameter gear 501B.

  The second gear 503 meshes with a third gear 504 provided above the second gear 503. The third gear 504 meshes with a swing gear 420 provided on the front side of the third gear 504.

  The swing gear 420 can swing around the third gear 504. The swing gear 420 is swingable between a transmission position that engages with a fourth gear 505 provided above the swing gear 420 and a blocking position where the engagement with the fourth gear 505 is released. .

  As shown in FIG. 3, the fourth gear 505 includes a second large-diameter gear 505A and a second small-diameter gear that is disposed on the right side of the second large-diameter gear 505A and has a smaller diameter than the second large-diameter gear 505A. 505B. The second large diameter gear 505A and the first small diameter gear 505B are inserted through the same gear shaft.

  The second small diameter gear 505B meshes with a first drive gear 608 provided below the second small diameter gear 505B.

  As shown in FIG. 9, the first drive gear mechanism 602 has a fifth gear 506 and a sixth gear 507. The fifth gear 506 is provided above the third gear 504 and meshes with the third gear 504.

  The fifth gear 506 meshes with a sixth gear 507 provided obliquely above the fifth gear 506.

  The sixth gear 507 includes a third large-diameter gear 507A and a third small-diameter gear 507B that is disposed on the left side of the third large-diameter gear 507A and has a smaller diameter than the third large-diameter gear 507A. The third large-diameter gear 507A and the third small-diameter gear 507B are integrally formed and are inserted through the same gear shaft.

  An electromagnetic clutch 410 is provided obliquely above the third large-diameter gear 507A. The electromagnetic clutch 410 has a clutch gear 508 that meshes with the third large-diameter gear 507A.

  The electromagnetic clutch 410 is a known switch that switches whether the driving force input to the third large-diameter gear 507A is transmitted to the seventh gear 509 and the eleventh gear 514 provided on the front and rear sides of the electromagnetic clutch 410. It is a clutch. Energization of the electromagnetic clutch 410 is controlled by the control device 450.

  When the electromagnetic clutch 410 is energized and operated, the driving force transmitted to the clutch gear 508 is transmitted to the seventh gear 509 and the eleventh gear 514.

  On the contrary, when the energization of the electromagnetic clutch 410 is released, the driving force transmitted to the clutch gear 508 is not transmitted to the seventh gear 509 and the eleventh gear 514.

  The second drive gear mechanism 603 is a gear train having a seventh gear 509, an eighth gear 510, a ninth gear 511, a tenth gear 512, and a first cam gear 513.

  A seventh gear 509 is provided on the front side of the electromagnetic clutch 410. The seventh gear 509 includes a fourth large-diameter gear 509A and a fourth small-diameter gear 509B that is disposed on the left side of the fourth large-diameter gear 509A and has a smaller diameter than the fourth large-diameter gear 509A. The fourth large-diameter gear 509A and the fourth small-diameter gear 509B are integrally formed and are inserted through the same gear shaft. The fourth small diameter gear 509B meshes with an eighth gear 510 provided on the front side of the seventh gear 509.

  The eighth gear 510 meshes with a ninth gear 511 provided on the front side of the eighth gear 510. The ninth gear 511 includes a fifth large-diameter gear 511A and a fifth small-diameter gear 511B that is provided on the right side of the fifth large-diameter gear 511A and has a smaller diameter than the fifth large-diameter gear 511A. The fifth large-diameter gear 511A and the fifth small-diameter gear 511B are integrally formed and are inserted through the same gear shaft.

  The fifth small diameter gear 511 </ b> B meshes with a tenth gear 512 provided on the front side of the ninth gear 511. The tenth gear 512 has a sixth large-diameter gear 512A and a sixth small-diameter gear 512B that is provided on the right side of the sixth large-diameter gear 512A and has a smaller diameter than the sixth large-diameter gear 512A. The sixth small diameter gear 512B meshes with the seventh large diameter gear 513A.

  The third drive gear mechanism 604 is a gear train having an eleventh gear 514, a twelfth gear 515, a thirteenth gear 516, and a second cam gear 517.

  The eleventh gear 514 is provided on the rear side of the electromagnetic clutch 410 and meshes with a twelfth gear 515 provided obliquely below the eleventh gear 514.

  The twelfth gear 515 meshes with a thirteenth gear 516 provided obliquely below the twelfth gear 515.

  The thirteenth gear 516 meshes with a second cam gear 517 provided obliquely below the thirteenth gear 516.

  Next, the operation of the interlocking mechanism 600 will be described in detail. First, the operation of the interlocking mechanism 600 when the motor 400 rotates forward will be described. When control device 450 rotates motor 400 normally, each gear of interlocking mechanism 600 rotates in the direction of the arrow shown in FIG.

  When the motor 400 rotates forward, the third gear 504 rotates counterclockwise in the drawing. In conjunction with the rotation of the third gear 504, the swing gear 420 disposed at the blocking position swings to the transmission position and meshes with the second large diameter gear 505A, so that the second large diameter gear 505A is illustrated. Rotates counterclockwise.

  When the second large-diameter gear 505A rotates counterclockwise in the figure, the second small-diameter gear 505B rotates counterclockwise in the figure, and the first drive gear 608 rotates clockwise in the figure. As a result, the first roller 81 rotates.

  At this time, the electromagnetic clutch 410 is not energized, and the driving force of the motor 400 is not transmitted to the second driving gear mechanism 603 and the third driving gear mechanism 604.

  Further, at this time, the first cam 250 is arranged so that the arrangement mode of each developing roller 110 is the color mode shown in FIGS. 7A and 8A, and as shown in FIG. The convex portion 83 is disposed below the first cam surface 304, the bearing 84 abuts on the first cam surface 304, and a nip portion is formed by the first pressure contact force.

  Thereby, color printing can be executed in a state where the nip portion is formed by the first pressure contact force. Hereinafter, a state in which each developing roller 110 is arranged in the color mode and the nip portion is formed by the first pressure contact force is referred to as an initial state.

  As described above, when the electromagnetic clutch 410 is energized in the initial state, the driving force of the motor 400 is also transmitted to the second drive gear mechanism 603 and the third drive gear mechanism 604.

  At this time, as shown in FIG. 9, each gear of the second drive gear mechanism 603 rotates in the direction shown. The tenth gear 512 rotates clockwise in the figure, and in conjunction with the rotation of the tenth gear 512, the first cam gear 513 rotates counterclockwise in the figure. As a result, the first cam 250 moves forward.

  Here, since the first cam 250 moves forward from the state in which each developing roller 110 is arranged in the color mode, the separation lever 64 does not contact the first inclined surface 201 and the second inclined surface 202. The arrangement mode of each developing roller 110 is maintained in the color mode.

  Further, in conjunction with the rotation of each gear of the second drive gear mechanism 603, each gear of the third drive gear mechanism 604 rotates in the direction shown in FIG. The thirteenth gear 516 rotates counterclockwise in the figure, and in conjunction with the rotation of the thirteenth gear 516, the second cam gear 517 rotates clockwise in the figure. Thereby, the 2nd cam 301 moves back.

  That is, when the electromagnetic clutch 410 is energized when the motor 400 rotates forward, the second cam 301 moves rearward in conjunction with the first cam 250 moving forward.

  Thus, when the motor 400 is rotating forward, the control device 450 can drive the first cam 250 and the second cam 301 at the same time by controlling only the energization of the electromagnetic clutch 410. . Thereby, it is possible to simplify the control of the control device 450 while simultaneously driving the displacement mechanism 200 and the pressure contact force changing mechanism 300.

  When the second cam 301 moves rearward to a predetermined position while the arrangement mode of each developing roller 110 is maintained in the color mode, and the nip portion is formed by the third press contact force, The energization is released. Thereby, color printing can be performed in a state where the nip portion is formed by the third pressure contact force. For example, color printing can be performed on thick paper or envelopes thicker than the paper P.

  Next, the operation of the interlocking mechanism 600 when the motor 400 rotates in the reverse direction will be described. When the controller 450 rotates the motor 400 in the initial state, each gear of the interlocking mechanism 600 rotates in the direction opposite to the direction of the arrow shown in FIG.

  When the motor 400 rotates in the reverse direction, the third gear 504 rotates in the clockwise direction. As a result, the swing gear 420 is maintained at the cutoff position, and the meshing between the swing gear 420 and the second large diameter gear 505A is released, so that the transmission of the driving force to the first roller 81 is blocked.

  At this time, when the electromagnetic clutch 410 is energized, the driving force of the motor 400 is transmitted to the second drive gear mechanism 603 and the third drive gear mechanism 604.

  Each gear of the second drive gear mechanism 603 rotates in the direction opposite to the direction of the arrow shown in FIG. The tenth gear 512 rotates counterclockwise, and in conjunction with the rotation of the tenth gear 512, the first cam gear 513 rotates clockwise. Thereby, the 1st cam 250 moves back.

  Further, in conjunction with the rotation of each gear of the second drive gear mechanism 603, each gear of the third drive gear mechanism 604 rotates in the direction opposite to the direction of the arrow shown in FIG. The thirteenth gear 516 rotates clockwise, and the second cam gear 517 rotates counterclockwise in conjunction with the rotation of the thirteenth gear 516. As a result, the second cam 301 moves forward.

  That is, when the electromagnetic clutch 410 is energized when the motor 400 rotates in the reverse direction, the second cam 301 moves forward in conjunction with the first cam 250 moving backward.

  Thereby, at the same time when the arrangement mode of each developing roller 110 is switched from the color mode to the monochrome mode, the second cam 301 moves forward to a predetermined position, and the state shown in FIG. The pressure contact force is the third pressure contact force.

  Then, after the energization of the electromagnetic clutch 410 is released, the controller 450 causes the motor 400 to rotate forward, so that monochrome printing can be performed in a state where the nip portion is formed by the third press contact force. For example, monochrome printing can be performed on a thick paper or envelope thicker than the paper P.

  In this embodiment, as described above, the second cam 301 moves forward to a predetermined position at the same time when the mode of arrangement of each developing roller 110 is switched from the color mode to the monochrome mode, and FIG. c). However, the present invention is not limited to this, and at the same time when the arrangement mode of each developing roller 110 is switched from the color mode to the monochrome mode, the state shown in FIG. The structure which maintains may be sufficient.

  In other words, when the arrangement mode of each developing roller 110 is switched from the color mode to the monochrome mode, the state is as shown in FIG. 4A. From this state, the second cam 301 further moves forward to a predetermined position. 4B may be configured as shown in FIG. Thereby, monochrome printing can be executed in a state where the nip portion is formed by the first pressure contact force.

  In the present embodiment, the first cam gear 513 and the second cam gear 517 are provided separately, but the first cam gear 513 and the second cam gear 517 may be configured as an integral gear.

  Furthermore, after the controller 450 rotates the motor 400 in the reverse direction in the state where the arrangement mode of each developing roller 110 is the monochrome mode and the nip portion is formed by the third press contact force as described above, When the clutch 410 is energized, the mode of arrangement of each developing roller 110 is switched from the monochrome mode to the non-supply mode.

  At the same time when the arrangement mode of each developing roller 110 is switched from the monochrome mode to the non-supply mode, the second cam 301 moves forward to a predetermined position, and the state shown in FIG. And the second roller 82 are released from pressure contact.

  As described above, when the motor 400 is rotating in the reverse direction, the control device 450 can drive the first cam 250 and the second cam 301 simultaneously only by controlling the energization of the electromagnetic clutch 410. it can. Thereby, it is possible to simplify the control of the control device 450 while simultaneously driving the displacement mechanism 200 and the pressure contact force changing mechanism 300.

  Further, when the toner image is not formed on the paper P, that is, when the image forming unit 30 does not form an image on the paper P, the pressure contact between the first roller 81 and the second roller 82 is released. The load applied to the second roller 82 can be reduced, and deterioration of the fixing device 80 can be suppressed.

  In this embodiment, the interlocking mechanism 600 and the first roller 81 are driven by the motor 400, and only one motor needs to be controlled, so that the control of the control device 450 can be simplified. it can.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Housing | casing 30 Image forming part 40 Process unit 61 Photosensitive drum 63 Pressing member 64 Separation lever 80 Fixing device 81 1st roller 82 2nd roller 83 Convex part 84 Bearing 85 Pressure contact mechanism 100 Developing cartridge 101 Protrusion 110 Development Roller 200 Displacement mechanism 201 First inclined surface 202 Second inclined surface 203 First holding surface 204 Second holding surface 205 Second connecting portion 208 First rack gear 209 Cam drive gear 250 First cam 300 Pressure contact force changing mechanism 301 Second cam 302 Second rack gear 303 Guide portion 304 First cam surface 305 Second cam surface 306 Third cam surface 307 Fourth cam surface 310 First connecting portion 400 Motor 410 Electromagnetic clutch 420 Oscillating gear 450 Controller 508 Clutch gear 513 First Cam gear 517 2nd Mugiya 600 interlocking mechanism 601 fixing the drive gear mechanism 602 first driving gear mechanism 603 second drive gear mechanism 604 third drive gear mechanism 608 first driven gear

Claims (8)

A photoreceptor,
A developing unit for developing the electrostatic latent image formed on the photoreceptor;
A motor,
A displacement mechanism that is driven by a driving force from the motor and displaces the developing unit between a development position for developing the electrostatic latent image and a non-development position for developing the electrostatic latent image;
A transfer unit for transferring the developer image developed by the developing unit to a recording medium;
A first conveying member that conveys a recording medium on which the developer image is transferred by the transfer unit;
A second conveying member that forms a nip portion that sandwiches the recording medium with the first conveying member;
A pressure-contact mechanism that press-contacts one of the first transport member and the second transport member to the other transport member;
A pressure contact force changing mechanism that is driven by the driving force of the motor, displaces the one conveyance member in a direction away from the other conveyance member, and changes the pressure contact force of the nip portion;
An interlocking mechanism for connecting the displacement mechanism and the pressure contact force changing mechanism to interlock the displacement mechanism and the pressure contact force changing mechanism;
A control device for controlling the motor;
An image forming apparatus comprising:   The said displacement mechanism is comprised by the 1st cam which has a 1st cam part which is a cam surface extended in the direction which cross | intersects the straight line which connects the said image development position and the said non-development position. Image forming apparatus. The first cam has a first rack gear;
The image forming apparatus according to claim 2, wherein the interlocking mechanism includes a first cam gear that meshes with the first rack gear.   4. The method according to claim 1, wherein the pressure contact force changing mechanism includes a second cam having a second cam portion that is a cam surface extending in a direction intersecting a pressure contact direction of the pressure contact mechanism. The image forming apparatus according to claim 1. The second cam has a second rack gear;
The image forming apparatus according to claim 4, wherein the interlocking mechanism includes a second cam gear that meshes with the second rack gear. A plurality of the photoreceptors are provided,
The developing unit is provided for each of the plurality of photoconductors,
The pressure contact force changing mechanism maintains a state in which the one transport member is displaced in the separating direction in a state where any one of the plurality of developing units is displaced to the developing position by the displacement mechanism. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.   The image forming apparatus according to claim 1, wherein the interlocking mechanism and the one conveyance member are driven by the motor. The first conveying member is a cylindrical fixing film,
The image forming apparatus according to claim 1, wherein the second transport member is a pressure roller that sandwiches the fixing film.

Images