JP2012238018A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of contributing to cost reduction of a fixing device, while facilitating removal of a paper jam in the fixing device.SOLUTION: The image forming apparatus comprises: a paper conveyance path for conveying paper on which a toner image is formed in a vertical direction toward a fixing device 20; an openable/closable cover 19 covering over the paper conveyance path and the fixing device 20; and a state changing mechanism 50 for changing a state of a pressure roller 40 between a release state and a pressure state T1 interlocked with the opening/closing operation of the cover 19. The state changing mechanism 50 has a coil spring 53 disposed to energize the pressure roller 40 toward a fixing roller 30 when the pressure roller 40 is set to the pressure state T1, and to weak energizing force of the pressure roller 40 to the fixing roller 30 when the pressure roller 40 is set to the release state.

Description

  The present invention relates to an image forming apparatus including a fixing device that performs a toner image fixing process on a paper sheet on which a toner image is formed by a predetermined image forming process.

  Conventionally, an image forming apparatus as described in Patent Document 1 is known. The image forming apparatus conveys a sheet on which a toner image has been transferred by performing an image forming process in an image forming unit along a conveying path laid in a vertical direction, and faces the upper end of the conveying path. After fixing the toner image on the paper with the fixing device arranged, the paper is discharged to a paper discharge tray provided above the fixing device.

  The conveyance path and the fixing device are disposed immediately inside a main body cover that can be opened and closed on a side wall of the image forming apparatus. Therefore, when a paper jam occurs in the conveyance path or the fixing device, the position where the paper jam occurs is exposed to the outside by opening the main body cover, so that the work of clearing the paper jam can be easily performed.

  The fixing device, on the other hand, is disposed opposite to the heating roller for fixing the sheet by heating, and the peripheral surface is pressed against the peripheral surface of the heating roller by the biasing force of a predetermined biasing member. And a pressure roller. Then, the sheet is supplied to a nip portion between a heating roller and a pressure roller each rotating around its own axis, and is subjected to a fixing process while being conveyed in the nip state.

  Therefore, when a paper jam occurs in the fixing device, after the main body cover is opened, the pressure roller is separated from the heating roller to remove the paper nip state, and then the jammed paper is pulled out of the fixing device. Is usually done. However, in this case, after the main body cover is opened, an operation for further separating the pressure roller from the heating roller has to be performed, which is inconvenient and inconvenient.

  Therefore, in the image forming apparatus described in Patent Document 1, the opening / closing operation of the main cover is interlocked with the separation / contact operation between the heating roller and the pressure roller so that the main body cover is opened. The pressure roller is automatically separated from the heating roller to release the pressure between them. By doing so, the pressure roller automatically separates from the heating roller just by opening the main body cover when a paper jam occurs, so there is no need to perform the operation of pulling them apart. The workability of the cancellation work can be improved.

JP-A-2005-37542

  However, in the structure described in Patent Document 1, when the main body cover is opened, the structure for securing the separated state of the pressure roller from the heating roller against the urging force of the urging member that is further strengthened. As a result, the configuration of the fixing device becomes complicated and the cost of the apparatus increases.

  The present invention has been made in order to eliminate the above-described inconveniences, and image formation that can contribute to reduction in apparatus cost while achieving ease of paper jam elimination work in a fixing apparatus. The object is to provide a device.

  The invention according to claim 1 further includes a fixing device that fixes the toner image to the paper while conveying the paper on which the toner image is formed by a predetermined image forming process, and the fixing device transfers the paper onto the paper. A heating member that heats and melts the toner image, and a pressurizing member that changes state between a pressurizing state in which the paper is pressed toward the heating member and a released state in which the pressurization is released. In the image forming apparatus, a conveyance path that conveys the sheet on which the toner image is formed toward the fixing device, an openable / closable cover body that covers the conveyance path and the fixing device, and an opening / closing operation of the cover body And a state change mechanism that changes the state of the pressure member between the released state and the pressure state, and the state change mechanism is pivotally supported around a support shaft and is supported by the state change mechanism. Depending on the opening / closing operation of the cover body An operation body that performs a predetermined operation; and an urging member that urges the operation body, and the operation body is urged by the urging member toward one direction in a rotation direction around the support shaft. In addition, when the pressure member is turned in one direction by the biasing, the pressure member is in a pressurized state, and the biasing member is biased in the turning direction around the support shaft in the other direction. The cover member has an operating body pressing plate and a return protrusion, and the operating body pressing plate closes the cover body. The operating body is rotated in the one direction to operate in the pressurized state and is brought into contact with the return protrusion, and when the return protrusion opens the cover body, the operation body is moved in the other direction. It is characterized in that it is rotated to the side and operated in the release state. It is intended.

  In the invention according to claim 1, the “released state” in the requirement “a pressure member that changes state between a pressurized state in which the sheet is pressurized toward the heating member and a released state in which the pressure is released” is the heating This includes a state in which the pressure is released to the extent that the sheet sandwiched between the member and the pressure member can be easily pulled out to a state in which the pressure is completely released.

  According to such a configuration, the sheet on which the toner image is formed by the image forming process is introduced into the fixing device disposed opposite to the upper end of the sheet through the conveyance path, where the heating member and the pressurized state set to the pressure are set. The toner image is conveyed while being subjected to the fixing process of the toner image in a state where the toner is melted by obtaining heat from the heating member while being pressed by the urging force of the urging member between the pressure member and the fixing process is completed. Afterwards it is discharged outside.

  When a paper jam occurs in the fixing device and the cover body is opened to eliminate the paper jam, the state change mechanism applies pressure to the heating member in conjunction with the opening operation of the cover body. Since the pressure member is changed to a released state in which the pressure state is released by weakening the biasing force of the biasing member, the jammed paper between the heating member and the pressure member is easily pulled out, and the paper jam occurs. Is resolved.

  As described above, the biasing member included in the state change mechanism biases the pressing member toward the heating member when the pressing member is set to the pressing state, while the pressing member is set to the release state. Since the biasing force of the pressure member toward the heating member is weakened when the pressure member is pressed, when the pressure member is set to the released state as in the prior art, the large biasing member is There is no inconvenience that the structure is complicated and the cost of the device is increased to cope with the power, and it contributes to the reduction of the device cost, and the ease of the operation to clear the paper jam in the fixing device. Secured.

  According to a second aspect of the present invention, in the first aspect of the invention, the state change mechanism is linked to the operating body, and the pressing member is operated by the operating body when the cover body is closed. A pressing plate that presses the heating plate toward the heating member, and the biasing member is pressed by the biasing force of the biasing member while the cover body is closed. It is characterized in that it is stretched between the operating body and the pressing plate so that the urging force of the urging member is weakened in the opened state.

According to such a configuration, the pressing plate presses the pressing member by the biasing force of the biasing member by the operation of the operating body by closing the cover body, whereby the pressing member pressurizes the heating member. It becomes a state. In this state, the sheet is supplied to the nip portion between the heating member and the pressure member, whereby the toner image on the sheet is fixed.

  On the other hand, when the cover body is opened for paper jam clearing work or the like, the opening operation of the cover body is transmitted to the pressing plate via the operating body and the urging member.

  The urging member is configured such that the pressing plate is pressed by the urging force of the urging member while the cover body is closed, while the urging force of the urging member is weakened while the cover body is opened. Since the tension member is stretched between the operating body and the pressing plate, when the cover body is opened, the pressing force of the pressing plate to the pressing member by the urging member is weakened. The pressure applied to the heating member is weak. Therefore, the paper jammed between the pressure member and the heating member can be easily pulled out from both.

  According to a third aspect of the present invention, in the first or second aspect of the invention, the operating body protrudes upward from the base end side in a state where the pressurizing member is set in a pressurized state. A support shaft having a first arm and a second arm projecting from the base end side toward the pressure member side, and the base end side extending in the paper width direction perpendicular to the paper transport direction The first arm is provided with an operation portion that is operated by interfering with the opening / closing operation of the cover body, and the pressing plate is The urging member extends in a direction orthogonal to the direction in which the support shaft extends and is positioned directly below the support shaft, and the urging member presses the pressure member on the tip of the second arm and the pressing plate. Stretched between the opposite end and the opposite end, the V-arm and the pressing Is the center of the biasing member in a state in which the biasing member applies a biasing force to the pressing plate by turning in one direction around the support shaft of the V-shaped arm by closing the cover body. The axis of the support shaft is disposed at one position of the center line with respect to the line, and the attachment is performed by turning in the other direction around the support shaft of the V-arm by opening the cover body. In a state where the urging force applied to the pressing plate by the urging member is weakened, the axis of the support shaft is on the opposite side of the center line with respect to the center line of the urging member. The relative positional relationship is set so as to be arranged at the position on the other side of the center line.

  According to such a configuration, when the cover body is closed, the operation portion provided on the first arm of the V-shaped arm interferes with the cover body, so that the pressure member is rotated around the support shaft via the pressing plate. The urging force of the generated urging member is applied, and thereby, the urging force is pressed against the heating member.

  When the cover body is opened in this state, the operating portion of the first arm is guided by the opening operation of the cover body and rotates around the support shaft, whereby the second arm is rotated by the same rotation of the V-shaped arm. The urging member stretched between the front end of the pressing plate and the rear end of the pressing plate is shortened, and the urging force of the urging member gradually decreases, so when the opening of the cover body is completed, The biasing force of the biasing member is weakened and is minimized or almost nonexistent.

  Then, the support member is supported with respect to the center line of the urging member in a state in which the urging member applies an urging force to the pressing plate by turning in one direction around the support shaft of the V-shaped arm by closing the cover body. The urging force that the urging member applies to the pressing plate by turning in the other direction around the support shaft of the V-shaped arm by opening the cover body is arranged at a position on one side of the center line. In a weakened state, the V-arm is arranged such that the shaft center of the support shaft is located at one side and the other side of the center line opposite to the center line with respect to the center line of the biasing member Since the relative positional relationship between each other and the pressing plate is set, when the cover body is closed (that is, the axis of the support shaft is one of the center lines with respect to the center line of the urging member). When the urging force of the urging member is applied to the second arm of the V-shaped arm, The urging force of the urging member does not cause the second arm of the V-shaped arm to be directed in the opposite direction, and the urging member applies the urging force to the pressure member. The application state of power, that is, the pressurization state of the pressurizing member to the heating member is stabilized.

  On the other hand, when the closed cover body is opened (that is, the axis of the support shaft is opposite to the center line of the urging member with the center line on the opposite side of the center line. When arranged at the other side position), the urging force of the urging member acts to move the second arm of the V-shaped arm around the support shaft in a direction away from the pressing plate. The urging force of the urging member does not cause the V-shaped arm to face the pressing plate, and the application state of the urging force to the pressing member by the urging member is weakened.

  As described above, when the cover body is closed, the axis of the support shaft is arranged at a position on one side of the center line with respect to the center line of the biasing member, while when the cover body is opened. The shaft center of the support shaft with respect to the center line of the urging member is arranged at a position on the other side of the center line opposite to the one side position with respect to the center line. Despite being configured, the pressure member can be easily and stably switched between the released state where the pressure member is released from the pressure applied to the heating member and the pressurized state depending on the open / closed state of the cover body. It is done.

  According to the first aspect of the present invention, the urging member that urges the pressing member toward the heating member, provided in the state change mechanism, is applied when the pressing member is set in the pressing state. While the member is urged toward the heating member, it is disposed so as to weaken the urging force of the pressure member toward the heating member when the pressure member is set to the released state. In addition, when the pressure member is set to the released state, there is no inconvenience that the structure becomes complicated and the apparatus cost is increased to cope with the large urging force of the urging member, and the apparatus cost is reduced. In addition, it is possible to secure the ease of paper jam clearing operation in the fixing device.

  According to the second aspect of the present invention, the pressing plate is pressed by the biasing force of the biasing member while the cover body is closed, while the biasing force of the biasing member is weakened when the cover body is opened. When the cover body is closed, the sheet to be subjected to the fixing process is attached between the pressure member and the heating member. On the other hand, when the cover body is opened for paper jam clearing work, the urging force of the urging member is weakened while being pressed and clamped by the urging force of the urging member to ensure the fixing process. The paper jammed between the pressure member and the heating member can be easily pulled out.

  According to the invention of claim 3, when the cover body is closed, the shaft center of the support shaft is arranged at a position on one side of the center line with respect to the center line of the urging member. When the body is released, the axis of the support shaft is arranged at the other side of the center line opposite to the one position with respect to the center line of the biasing member. Therefore, it is easy between the release state in which the pressurization member is released from the pressurization to the heating member according to the open / closed state of the cover body, and the pressurized pressurization state, while having a simple configuration, and Switching can be performed in a stable state.

It is explanatory drawing of front sectional view for demonstrating one Embodiment of the internal structure of the printer which concerns on this invention. FIG. 2 is an exploded perspective view showing an embodiment of a fixing device. FIG. 3 is an assembled perspective view of the fixing device shown in FIG. 2. It is the IV-IV sectional view taken on the line of FIG. It is the fragmentary perspective view which looked at the cover body of the state set to the closed attitude from the back side. It is explanatory drawing for demonstrating the effect | action of a state change mechanism, and when a cover body is set to a closed posture, a V-arm is set to a pressure posture, and thereby a pressure roller is set to a pressure state. It shows the state that was done. It is explanatory drawing for demonstrating the effect | action of a state change mechanism, and when a cover body is open | released toward an open attitude | position, a V-shaped arm will be changed to a release attitude | position, and this will make a pressure roller into a release state. The changed state is shown.

  First, an outline of the internal structure of a printer as an image forming apparatus according to the present invention will be described with reference to FIG. FIG. 1 is a front cross-sectional view for explaining an embodiment of the internal structure of the printer according to the present invention. As shown in FIG. 1, a printer (image forming apparatus) 10 according to this embodiment includes a box-shaped apparatus main body 11 and a cover body 19 attached to the side surface of the apparatus main body 11 so as to be openable and closable. I have.

  The apparatus main body 11 includes an image forming unit 12 that forms an image based on image information transmitted from an external device such as a computer, and a fixing process performed on the toner image formed by the image forming unit 12 and transferred to the paper P. A fixing unit 13 for applying toner, a sheet storage unit 14 for storing a transfer sheet, and a toner supply unit 15 for supplying toner to the image forming unit 12, and an upper portion of the apparatus main body 11 after the fixing process. A paper discharge section 16 is formed through which the paper P is discharged.

  At an appropriate position on the upper surface of the apparatus main body 11, an operation panel (not shown) for inputting the output conditions of the paper P is provided. This operation panel is provided with a power key, a start button (not shown), various keys for inputting output conditions, and the like.

  The image forming unit 12 forms a toner image on the paper P fed from the paper storage unit 14. In the present embodiment, the image forming unit 12 is sequentially arranged from the upstream side (left side in FIG. 1) to the downstream side. The magenta unit 12M using the magenta toner (developer), the cyan unit 12C using the cyan toner, the yellow unit 12Y using the yellow toner, and the black using the black toner. Unit 12K.

  Each of the units 12M, 12C, 12Y, and 12K is provided with a photosensitive drum 121 and a developing device 122, respectively. The photosensitive drum 121 is for forming an electrostatic latent image and a toner image along the electrostatic latent image on the peripheral surface, and is an extremely smooth amorphous silicon layer that is tough and has excellent wear resistance on the peripheral surface. Are made suitable for forming these images. Each photosensitive drum 121 is supplied with toner from a corresponding developing device 122 while rotating counterclockwise in FIG. Each developing device 122 is supplied with toner from the toner supply unit 15.

  A charging device 123 is provided immediately below each photoconductor drum 121, and an exposure device 124 is provided further below each charging device 123. Each photosensitive drum 121 is uniformly charged by the charging device 123, and laser light corresponding to each color based on image data input from a computer or the like is charged from each exposure device 124 after being charged. By irradiating the peripheral surface of the photosensitive drum 121, an electrostatic latent image is formed on the peripheral surface of each photosensitive drum 121. By supplying toner from the developing device 122 to the electrostatic latent image, a toner image is formed on the peripheral surface of the photosensitive drum 121.

  A transfer belt 125 stretched between the driving roller 125 a and the driven roller 125 b is provided at a position above the photosensitive drum 121 so as to contact the photosensitive drum 121. The transfer belt 125 is driven against a peripheral surface of the photosensitive drum 121 by a transfer roller 126 provided corresponding to each photosensitive drum 121, and is driven with a driving roller 125a and a driven roller while being synchronized with the photosensitive drum 121. It circulates between 125b.

  Therefore, when the transfer belt 125 circulates, the toner image of the magenta toner is transferred to the surface of the transfer belt 125 by the photosensitive drum 121 of the magenta unit 12M, and then the photosensitive member of the cyan unit 12C is located at the same position on the transfer belt 125. The transfer of the cyan toner image by the drum 121 is performed in the overcoating state, and then the transfer of the yellow toner image by the photosensitive drum 121 of the yellow unit 12Y is performed in the overcoating state at the same position on the transfer belt 125. Then, the transfer of the black toner image by the photosensitive drum 121 of the last black unit 12K is performed in an overcoated state, whereby a color toner image is formed on the surface of the transfer belt 125. The color toner image formed on the surface of the transfer belt 125 is transferred to the paper P conveyed from the paper storage unit 14.

  A cleaning device 127 that removes and cleans residual toner on the peripheral surface of the photosensitive drum 121 is provided at the left position of each photosensitive drum 121 in FIG. The peripheral surface of the photosensitive drum 121 cleaned by the cleaning device 127 goes to the charging device 123 for a new charging process.

  Waste toner removed from the peripheral surface of the photosensitive drum 121 by the cleaning device 127 is collected and stored in a toner collection bottle (not shown) through a predetermined path.

  At the right position in FIG. 1 of the image forming unit 12, a paper conveyance path 111 extending in the vertical direction along the left surface of the sub 19 is formed. The sheet conveying path 111 is provided with a pair of conveying rollers 112 at appropriate positions, and the sheet fed from the sheet storing unit 14 is transferred to a transfer belt 125 that is wound around a driving roller 125 a by driving the conveying roller pair 112. It is conveyed toward.

  In the sheet conveyance path 111, a second transfer roller 113 that is in contact with the surface of the transfer belt 125 is provided at a position facing the driving roller 125 a, and the sheet P being conveyed along the sheet conveyance path 111 is separated from the transfer belt 125. The toner image on the transfer belt 125 is transferred onto the paper P by being pressed and sandwiched between the second transfer roller 113.

  The fixing unit 13 performs a fixing process on the toner image on the paper transferred by the image forming unit 12 and includes a fixing device 20 described later. The fixing device 20 is provided at a position immediately above the second transfer roller 113, and the toner image on the transfer belt 125 is transferred by passing through the nip portion between the transfer belt 125 and the second transfer roller 113. The sheet P supplied to the fixing unit 13 is subjected to fixing processing by the fixing device 20.

  The sheet P with the color image for which the fixing process has been completed passes through a paper discharge conveyance path 114 extending from the upper part of the fixing unit 13 to the paper discharge tray 161 of the paper discharge unit 16 provided at the top of the apparatus main body 11. It will be discharged towards.

  The paper storage unit 14 includes a paper tray 141 that is detachably mounted at a position below the exposure device 124 in the apparatus main body 11. A sheet bundle is stored in the sheet tray 141.

  The paper tray 141 is configured to include a box body whose upper surface is open on the entire surface, and can store a paper bundle P1 in which a plurality of paper sheets P are stacked. The uppermost sheet P of the sheet bundle P1 stored in the sheet tray 141 is drawn out from the sheet bundle P1 toward the sheet conveyance path 111 by driving the pickup roller 142 from the upper surface of the downstream end (right end in FIG. 1). The sheet P fed out one by one passes through the sheet conveyance path 111 by the driving of the conveyance roller pair 112 toward the nip portion between the second transfer roller 113 and the transfer belt 125 in the image forming unit 12. Sent in.

  The toner supply unit 15 includes four toner cartridges 151 (magenta cartridge 151M, cyan cartridge 151C, yellow cartridge 151Y and black cartridge 151Y corresponding to the units 12M, 12C, 12Y and 12K of the image forming unit 12, respectively. Cartridge 151K) is provided. The developing devices 122 of the units 12M, 12C, 12Y, and 12K are supplied with toner from the corresponding cartridges 151M, 151C, 151Y, and 151K when the remaining amount decreases.

  The cover body 19 is moved to the right side in FIG. 1 of the image forming unit 12, the fixing unit 13, and the sheet storage unit 14 by changing the posture between a closed posture S1 (shown by a solid line in FIG. 1) and an open posture S2. It can be opened and closed. The cover body 19 is normally set in the closed position S1 so that the sheet from the sheet storage unit 14 is conveyed toward the second transfer roller 113 between the image forming unit 12 and the right side in FIG. The sheet conveyance path 111 is formed.

  Then, when a paper jam occurs in the conveying roller pair 112 or the fixing unit 13, the cover body 19 is opened (that is, the posture is changed from the closed posture S1 to the open posture S2), and thereby the image forming unit 12 exposed to the outside and The jammed paper can be easily removed from the fixing unit 13.

  Such a cover body 19 is formed in an inverted S shape in front view in FIG. 1 so as to follow the paper transport path 111 and the paper discharge transport path 114, and the lower end is a predetermined portion of the apparatus main body 11. The support shaft 191 supported by the frame can be rotated around the support shaft 191, and the posture can be changed between the closed posture S1 and the open posture S2 by rotating forward and backward around the support shaft 191.

  The cover body 19 is reversely conveyed for duplex printing in which the paper P that has passed through the second transfer roller 113 is reversed and then returned to the paper conveyance path 111 for printing on the back side. Although a path is provided, description thereof is omitted.

  FIG. 2 is an exploded perspective view showing an embodiment of the fixing device 20, and FIG. 3 is an assembled perspective view thereof. 4 is a cross-sectional view taken along line IV-IV in FIG. 2 to 4, the XX direction is referred to as the left-right direction, and the YY direction is referred to as the front-rear direction. In particular, the -X direction is referred to as the left, the + X direction is referred to as the right, the -Y direction is referred to as the front, and the + Y direction is referred to as the rear. .

  First, as shown in FIG. 2, the fixing device 20 includes an open housing 21 that is fixed to a predetermined frame of the apparatus main body 11 of the printer 10, and a fixing roller ( (Heating member) 30, a pressure roller (pressure member) 40 disposed opposite to the fixing roller 30 at a rear position of the housing 21, and the pressure roller 40 in conjunction with the opening / closing operation of the cover body 19. A state change mechanism 50 is provided for changing the state between a pressure state T1 (see FIG. 4) in which pressure is applied to the fixing roller 30 and a release state T2 in which the pressure state T1 is released.

  The housing 21 is installed between a pair of side plates 22 having a substantially rectangular shape in the left-right direction, a front installation plate 23 installed between the front edge portions of the pair of side plates 22, and a lower edge portion of the rear portion. A rear erection plate 24 elongated in the left-right direction, and a pedestal plate 25 extending from the rear erection plate 24 toward the front upper side are provided.

  Each side plate 22 is provided with an inclined long hole 221 that is inclined downward from the rear to the front for mounting the fixing roller 30. The fixing roller 30 is attached to the fixing device 20 by fitting the right and left ends of the fixing roller 30 into the inclined long holes 221.

  The pedestal plate 25 includes a standing plate 251 erected from the front edge of the rear erection plate 24 and a horizontal plate 252 extending forward from the upper edge of the erection plate 251. ing. The horizontal plate 252 is provided with bracket plates 253 erected from the left and right edges. The pair of bracket plates 253 are for supporting a V-shaped arm 51 described later.

  The fixing roller 30 performs a fixing process of the toner image on the paper P by a heat process by transferring heat to the paper P, and an energizing heating element as a heat source such as a halogen lamp is mounted inside. For example, a metal shaft cylinder 31 such as an aluminum alloy, and a metal core such as an aluminum alloy that is concentrically fitted to the shaft cylinder 31 so as to be integrally rotatable or formed integrally with the shaft cylinder 31 from the beginning. The fixing roller main body 32 is provided.

The fixing roller main body 32 has a peripheral surface portion with a thickness dimension set as thin as possible. As a result, heat from the heat source is quickly transferred to the peripheral surface, so that the startup speed of the printer 10 is increased. Has been made.

  Both ends of the shaft cylinder 31 protrude outward from the both ends of the fixing roller main body 32 by a predetermined dimension, and the outwardly protruding portions are fitted into the inclined elongated holes 221 of the side plates 22. As a result, the fixing roller 30 is attached to the housing 21.

  Further, a gear 33 (FIG. 3) is externally fitted to one end portion of the shaft cylinder 31 (the left end portion in the example shown in FIG. 2) so as to be concentric and integrally rotatable. Then, a driving force from a driving motor (not shown) is transmitted through the gear 33, so that the fixing roller 30 is driven and rotated around the center of the cylinder.

  The pressure roller 40 is used to press and hold the paper P with the fixing roller 30 and can be pressed forward by a press plate 52 (to be described later) of the state change mechanism 50. As shown in FIG. 4, a pressurization state T <b> 1 that pressurizes the sheet P toward the peripheral surface of the fixing roller 30 in conjunction with the opening / closing operation of the cover body 19 by a predetermined operation of the state change mechanism 50, and the pressurization The state is changed between a release state T2 (indicated by a two-dot chain line in FIG. 4).

  The pressure roller 40 includes a shaft cylinder 41 made of a metal such as an aluminum alloy, whose end portions are loosely fitted in the inclined long holes 221 of the pair of side plates 22, and a concentric rotation with the shaft cylinder 41. An elastic cylinder 42 made of, for example, silicon rubber, which is externally fitted, and a coating layer 43 made of, for example, a fluororesin or the like, laminated on the peripheral surface of the elastic cylinder 42 are provided.

  The shaft cylinder 41 is fitted in a mounting groove 521 of a pressing plate 52 described later in a state of loosely fitting in the inclined long hole 221 provided in the side plate 22.

  The pressure roller 40 is set to the pressure state T1 so that the peripheral surface presses the peripheral surface of the fixing roller 30 via the paper P, thereby compressing the elastic cylinder 42. It will be elastically deformed.

  The state change mechanism 50 is supported by a pair of bracket plates 253 provided on the base plate 25 (FIG. 2) of the housing 21 and has a V shape that operates by opening and closing the cover body 19. A V-shaped arm (operation body) 51, a pressing plate 52 that presses the shaft cylinder 41 of the pressure roller 40 at the front edge, and a coil spring (attached) stretched between the V-shaped arm 51 and the pressing plate 52 Force member) 53.

  Each V-shaped arm 51 includes a first arm 511 extending upward, and a second arm 512 projecting forward from a base end (lower part) of the first arm 511.

  On the other hand, a connecting shaft (support shaft) 54 passes through each bracket plate 253. Each V-shaped arm 51 is fixed at the same phase to each end of the connecting shaft 54 through which each bracket plate 253 penetrates the respective V-shaped arm 51, thereby being able to rotate integrally around the connecting shaft 54. It has become.

  Further, a locking projection for locking one end portion (front end portion) of the coil spring 53 formed by bending the front ends in opposite directions to each other at the front end of each second arm 512. 513 is provided.

Each pressing plate 52 is provided with a mounting groove 521 that is formed by recessing each front edge portion toward the rear, and is fitted to each end of the shaft tube 41. In addition, locking protrusions 522 for locking the other end portion (rear end portion) of the coil spring 53 formed by bending the respective rear edge portions in directions opposite to each other are provided. Yes.

  Further, each pressing plate 52 is provided with a rotation preventing protrusion 523 that protrudes downward from the lower edge of the front end. Each rotation prevention protrusion 523 is provided with a rotation prevention recess 524 that is recessed forward at each rear edge. On the other hand, each side plate 22 of the housing 21 is provided with a stopper 222 for externally fitting the rotation prevention recess 524 at a position corresponding to the rotation prevention protrusion 523. As a result, the pressing plate 52 in which the mounting groove 521 is externally fitted to the shaft cylinder 41 and the rotation prevention concave portion 524 is externally fitted to the stopper 222 is prevented from rotating around the shaft cylinder 41.

  The coil spring 53 is stretched between the locking protrusion 513 of the V-shaped arm 51 and the locking protrusion 522 of the pressing plate 52, whereby the V-shaped arm 51 and the pressing plate 52 are Are urged toward the direction in which the locking projections 513 and 522 approach each other. Therefore, when the V-arm 51 is set in the pressure posture U1 (indicated by a solid line in FIG. 4) so that the second arm 512 faces forward, the biasing force of the extended coil spring 53 causes the pressure roller 40 to The shaft cylinder 41 is pressed forward by the pressing plate 52. As a result, the pressure roller 40 is in a pressure state T <b> 1 in which the elastic cylinder 42 is pressed against the peripheral surface of the fixing roller 30 and elastically deformed.

  On the other hand, the posture is changed to the release posture U2 (indicated by a two-dot chain line in FIG. 4) by turning the V-shaped arm 51 from the pressure posture U1 by about 90 ° clockwise around the connecting shaft 54. When this occurs, the latching projection 513 of the second arm 512 of the V-shaped arm 51 approaches the latching projection 522 of the pressing plate 52, so that the biasing force of the coil spring 53 is weakened. As indicated by a two-dot chain line in FIG. 4, the release state T2 is obtained in which the elastic deformation of the elastic cylinder 42 is eliminated.

  In the present embodiment, the center line L1 of the coil spring 53 passes below the axis O of the connecting shaft 54 while the V-shaped arm 51 is set to the pressurizing posture U1. In a state where 51 is set to the release posture U2, the center line L2 of the coil spring 53 is relative to the V-shaped arm 51, the pressing plate 52, and the coil spring 53 so as to pass above the axis O of the connecting shaft 54. The positional relationship is set.

  Accordingly, when the V-shaped arm 51 is set to the pressurizing posture U1, the V-shaped arm 51 receives a biasing force from the coil spring 53 around the connecting shaft 54 in the counterclockwise direction, and thereby the applied force of the V-shaped arm 51 is increased. The pressure posture U1 is maintained in a stable state.

  On the other hand, when the V-shaped arm 51 is set to the release posture U2, the V-shaped arm 51 receives a biasing force from the coil spring 53 around the connecting shaft 54 in the clockwise direction, thereby releasing the V-shaped arm 51. State T2 is maintained in a stable state.

  In such a state change mechanism 50, operation protrusions (operation portions) 55 are provided at the tips of the first arms 511 of the V-shaped arms 51 so as to protrude in opposite directions. These operation protrusions 55 cause the V-shaped arm 51 to change its posture in conjunction with the opening / closing operation of the cover body 19.

FIG. 5 is a partial perspective view of the cover body 19 in a state in which the posture is set to the closed posture S1 as seen from the back surface side. In FIG. 5, for convenience of illustration, only the right side of the state change mechanism 50 is shown, and the drawing of the casing 21 is omitted. The direction display by X and Y in FIG. 5 is the same as in FIG. 2 (X is the left-right direction (−X: leftward, + X: rightward), Y is the front-rear direction (−Y: forward, + Y: rearward). )).

  As shown in FIG. 5, on the back side of the cover body 19, when the cover body 19 is closed at a position corresponding to the operation protrusion 55, the operation protrusion 55 that has been set in the release position U <b> 2 is provided. A pressing plate (operation body pressing plate) 192 that is pressed forward to change the posture to the pressing posture U1 and the operation protrusion 55 that has been set to the pressing posture U1 when the cover body 19 is opened are restored to the original. A return protrusion 193 for returning to the release posture U2 is provided.

  The pressing plate 192 is suspended from the top plate of the cover body 19, and the locking projection 513 of the V-shaped arm 51 which is set in the release posture U2 immediately before the opened cover body 19 is closed. The installation position and the length dimension are set so as to interfere.

  The return protrusion 193 is suspended from the top plate of the cover body 19 at a position slightly forward of the pressing plate 192, and the operation protrusion is necessary and sufficient when the V-arm 51 is set in the pressurizing posture U1. The hanging length from the top plate of the cover body 19 is set so as to interfere with the piece 55.

  As a result, an accommodation gap 194 is formed between the pressing plate 192 and the return projection 193 so that the operation projection 55 can be accommodated in a state where the V-shaped arm 51 is set in the pressurization posture U1.

  FIGS. 6 and 7 are explanatory views for explaining the operation of the state change mechanism 50. FIG. 6 shows that the V-arm 51 is in the pressurizing posture U1 when the cover body 19 is set in the closed posture S1. In this state, the pressure roller 40 is set to the pressure state T1, and FIG. 7 shows that the V-arm 51 is released when the cover body 19 is opened toward the opening posture S2. The state is changed to U2, and the pressure roller 40 is thereby changed to the release state T2, respectively. 7 and 8, only the components necessary for explaining the operation are described, and the description of other members such as the housing 21 is omitted.

  First, as shown in FIG. 6, when the cover body 19 is set to the closed position S1, the V-shaped arm 51 is set to the pressing position U1, thereby setting the pressure roller 40 to the pressing state T1. The operation protrusion 55 provided at the tip of the first arm 511 of the V-shaped arm 51 is fitted in the accommodation gap 194 between the pressing plate 192 and the return protrusion 193 of the cover body 19, and The urging force of the coil spring 53 is in contact with the return protrusion 193.

  At this time, the coil spring 53 stretched between the locking projection 513 at the tip of the second arm 512 and the locking projection 522 at the rear end of the coil spring 53 is in an extended state. Due to the urging force, the V-arm 51 is given a urging force counterclockwise around the connecting shaft 54 because the center line L1 of the coil spring 53 is located below the axis of the connecting shaft 54. The operation projecting piece 55 in the accommodation gap 194 is in a state of stopping against the return projecting piece 193.

  Further, at this time, the pressing plate 52 is pressed forward by the urging force of the coil spring 53 while being prevented from rotating by the stopper 222, whereby the shaft cylinder 41 is pressed by the mounting groove 521 of the pressing plate 52. The roller 40 is pressed against the peripheral surface of the fixing roller 30 and the portion thereof is in a state of being compressed and elastically deformed.

In such a state, the fixing roller 30 is driven and rotated, and the pressure roller 40 is rotated by the driving rotation of the fixing roller 30, and a contact position (nip) between the fixing roller 30 and the pressure roller 40. The sheet P immediately after the toner image is transferred by the image forming unit 12 is supplied to the sheet P), so that the fixing process of the toner image is performed on the sheet P.

  Next, when opening is started to change the position of the cover body 19 set to the closed position S1 to the open position S2 (that is, the cover body 19 is rotated clockwise around the support shaft 191 (FIG. 1)). Since the return protrusion 193 of the cover body 19 presses the operation protrusion 55 of the V-shaped arm 51 rearward, the V-shaped arm 51 is initially connected against the urging force of the coil spring 53. It rotates around the shaft 54 in the clockwise direction.

  When the center line L1 of the coil spring 53 moves above the axis of the connecting shaft 54 (in FIG. 7, the center line after movement is represented as a center line L2 and the center line L1 before movement). In this case, the urging force of the coil spring 53 acts to cause the V-shaped arm 51 to turn clockwise around the connecting shaft 54, so that the operation protrusion 55 is the pressing plate of the cover body 19. The front edge surface of 192 is pressed and stopped.

  When the opening operation of the cover body 19 is continued in this state, the pressing plate 192 moves rearward, so that the V-shaped arm 51 is operated by the urging force of the coil spring 53 as shown in FIG. While rotating in a sliding manner on the front edge surface of the pressing plate 192, it rotates clockwise around the connecting shaft 54. Incidentally, FIG. 7 shows a state in which the operation protrusion 55 is in contact with the lowermost end of the pressing plate 192.

  Then, in the state where the cover body 19 is completely released and the posture is set to the open posture S2, the coil spring 53 is in a state where the V-shaped arm 51 shown in FIG. 6 is set to the pressurizing posture U1. Since it is considerably shorter than that, the biasing force is weakened by the shortened amount. In particular, if the natural length of the coil spring 53 is set equal to the distance between the locking projections 513 and 522 when the V-arm 51 is set in the release posture U2, the V-arm 51 is in the release posture U2. In the changed state (that is, the cover body 19 is opened), the urging force of the coil spring 53 does not exist.

  As a result, the pressure roller 40 changes from the pressure state T1 due to the urging force of the coil spring 53 to the fixing roller 30 to the release state T2 where the urging force of the coil spring 53 hardly or does not exist. Since the state changes, it is possible to easily pull out the paper P sandwiched between the fixing roller 30 and the pressure roller 40 by opening the cover body 19 when a paper jam occurs in the fixing device 20. .

  As described above in detail, the printer 10 according to this embodiment includes the fixing device 20 that performs the toner image fixing process on the paper P while conveying the paper P on which the toner image is formed by the predetermined image forming process. The fixing device 20 includes a fixing roller 30 that heats the paper P by heat transfer, and a pressure state T1 that pressurizes the paper P toward the fixing roller 30 and a release state T2 that releases the pressure. A pressure roller 40 that changes state, a paper conveyance path 111 that conveys the paper P on which the toner image is formed, in the vertical direction toward the fixing device 20, and the paper conveyance path 111 and the fixing device. An openable / closable cover body 19 that covers 20 and a state change mechanism 50 that changes the state of the pressure roller 40 between the release state T2 and the pressure state T1 in conjunction with the opening / closing operation of the cover body 19 are provided. , The state change mechanism 50 urges the pressure roller 40 toward the fixing roller 30 when the pressure roller 40 is set to the pressure state T1, while the pressure roller 40 is set to the release state T2. A coil spring 53 is sometimes disposed so as to weaken the urging force of the pressure roller 40 against the fixing roller 30.

According to such a configuration, the sheet P on which the toner image is formed by the image forming process is introduced into the fixing device 20 disposed opposite to the upper end of the sheet P through the sheet conveying path 111 extending in the vertical direction. 30 and the pressure roller 40 set to the pressure state T1 are pressed by the urging force of the coil spring 53 while obtaining heat from the fixing roller 30 and being conveyed while being subjected to fixing processing of the toner image. After the fixing process is completed, the paper is discharged to the paper discharge tray 161.

  When a paper jam occurs in the fixing device 20 and the cover body 19 is opened to eliminate the paper jam, the state change mechanism 50 moves the fixing roller 30 against the fixing roller 30 in conjunction with the opening operation of the cover body 19. In order to change the state of the pressure roller 40 in the pressure state T1 to the release state T2 in which the pressure state T1 is released by weakening the urging force of the coil spring 53, the pressure roller 40 is moved between the fixing roller 30 and the pressure roller 40. The jammed paper P is easily pulled out and the paper jam is eliminated.

  As described above, the coil spring 53 included in the state change mechanism 50 urges the pressure roller 40 toward the fixing roller 30 when the pressure roller 40 is set to the pressure state T1. Since the pressure roller 40 is disposed so as to weaken the urging force toward the fixing roller 30 when the pressure roller 40 is set to the release state T2, the pressure roller 40 is set to the release state T2 as in the related art. In this case, there is no inconvenience that the structure of the coil spring 53 becomes complicated to cope with a large urging force of the coil spring 53 and the apparatus cost is increased, and it contributes to the reduction of the apparatus cost. It is possible to ensure the ease of paper jam clearing operation.

  The state change mechanism 50 is connected to the V-shaped arm 51 that performs a predetermined operation in accordance with the opening / closing operation of the cover body 19, and is linked to the V-shaped arm 51. The coil spring 53 has a pressing plate 52 that presses the pressure roller 40 toward the fixing roller 30 by the operation of the arm 51, and the coil spring 53 is attached to the coil spring 53 in a state where the cover body 19 is closed. While being pressed by the force, it is stretched between the V-shaped arm 51 and the pressing plate 52 so that the urging force of the coil spring 53 is weakened when the cover body 19 is opened.

  According to this configuration, the pressing plate 52 presses the pressure roller 40 by the urging force of the coil spring 53 by the operation of the V-shaped arm 51 by closing the cover body 19, whereby the pressure roller 40 is used as the fixing roller. It will be in the pressurization state T1 which pressurized 30. In this state, the paper P is supplied to the nip portion between the fixing roller 30 and the pressure roller 40, whereby the toner image on the paper P is fixed.

  On the other hand, when the cover body 19 is opened for paper jam clearing work or the like, the opening operation of the cover body 19 is transmitted to the pressing plate 52 via the V-shaped arm 51 and the coil spring 53.

  In the coil spring 53, the pressing plate 52 is pressed by the urging force of the coil spring 53 with the cover body 19 closed, while the urging force of the coil spring 53 is weakened with the cover body 19 opened. Thus, when the cover body 19 is opened, the pressing force of the pressing plate 52 against the pressing roller 40 by the coil spring 53 is weakened because it is stretched between the V-shaped arm 51 and the pressing plate 52. As a result, the pressure state T1 of the pressure roller 40 with respect to the fixing roller 30 is weakened. Accordingly, the paper P jammed between the pressure roller 40 and the fixing roller 30 is easily pulled out from both.

  The V-shaped arm 51 includes a first arm 511 projecting upward from the base end side in a state where the pressure roller 40 is set to the pressurizing state T1, and the pressure roller 40 from the base end side. And a second arm 512 projecting toward the side, and the base end side is pivotally supported around a connecting shaft 54 extending in the paper width direction orthogonal to the paper transport direction.

  The first arm 511 is provided with an operation protrusion 55 that is operated by interfering with the opening / closing operation of the cover body 19, the pressing plate 52 extends in a direction orthogonal to the extending direction of the connecting shaft 54, and The coil spring 53 is opposite to the tip of the second arm 512 and the end of the pressing plate 52 that presses the pressure roller 40. It is stretched between the side ends.

  Furthermore, the V-shaped arm 51 and the pressing plate 52 cause the coil spring 53 to urge the pressing plate 52 by urging in one direction around the connecting shaft 54 of the V-shaped arm 51 when the cover body 19 is closed. In the applied state, the center line of the coil spring 53 is positioned below the axis O of the connecting shaft 54 (the axis of the support shaft is one side of the center line with respect to the center line of the biasing member), and the cover The center line of the coil spring 53 in a state where the biasing force applied to the pressing plate 52 by the coil spring 53 is weakened by the rotation of the V-shaped arm 51 around the connecting shaft 54 due to the opening of the body 19 in the other direction. The relative positional relationship between each other is set so that the shaft moves beyond the axis O of the connecting shaft 54 upward (the axis of the support shaft is positioned on the other side of the center line with respect to the center line of the biasing member). Has been.

  According to this configuration, when the cover body 19 is closed, the second arm 512 is in a state in which the operation protrusion 55 provided on the first arm 511 of the V-shaped arm 51 is restricted in movement due to interference with the cover body 19. The pressure roller 40 is moved by the urging force of the coil spring 53 stretched between the front end of the pressing plate 52 and the rear end of the pressing plate 52 (the end of the pressing plate 52 opposite to the end pressing the pressing roller 40). The urging force of the coil spring 53 generated around the connecting shaft 54 is applied via the pressing plate 52, thereby pressing the contact with the fixing roller 30.

  When the cover body 19 is opened in this state, the operation protrusion 55 of the first arm 511 is guided by the opening operation of the cover body 19 and rotates around the connecting shaft 54, thereby causing the V-arm 51 to move the same. The coil spring 53 stretched between the front end of the second arm 512 and the rear end of the pressing plate 52 is shortened by the rotation, whereby the urging force of the coil spring 53 is gradually reduced. When the opening of the body 19 is completed, the urging force of the coil spring 53 is weakened, and is minimized or hardly exists.

  The center line of the coil spring 53 in a state where the coil spring 53 applies a biasing force to the pressing plate 52 due to the rotation of the V-arm 51 in one direction around the connecting shaft 54 by closing the cover body 19. While L1 is located below the axis O of the connecting shaft 54, the coil spring 53 is moved to the pressing plate 52 by the rotation of the V-arm 51 around the connecting shaft 54 in the other direction by opening the cover body 19. The relative relationship between the V-shaped arm 51 and the pressing plate 52 so that the center line L2 of the coil spring 53 moves upward beyond the axis O of the connecting shaft 54 in a state where the applied urging force is weakened. The positional relationship is set.

  Therefore, when the cover body 19 is closed and set in the closed posture S1 (that is, when the center line L1 of the coil spring 53 is located below the axis O of the connecting shaft 54), the coil spring 53 is attached. The urging force acts so that the second arm 512 of the V-shaped arm 51 is directed to the direction of the pressing plate 52 around the connecting shaft 54, whereby the urging force of the coil spring 53 causes the second arm 512 of the V-shaped arm 51 to move. Without being directed in the reverse direction, it is possible to stabilize the state in which the urging force is applied to the pressure roller 40 by the coil spring 53, that is, the pressure state T1 of the pressure roller 40 to the fixing roller 30.

On the other hand, when the closed cover body 19 is opened and set to the open posture S2 (that is, when the center line L2 of the coil spring 53 moves upward beyond the axis O of the connecting shaft 54). The urging force of the coil spring 53 acts so that the second arm 512 of the V-shaped arm 51 is directed in the direction away from the pressing plate 52 around the connecting shaft 54, whereby the urging force of the coil spring 53 is reduced. The V-arm 51 does not face the pressing plate 52, and the application state of the urging force to the pressure roller 40 by the coil spring 53 can be weakened.

  Thus, when the cover body 19 is closed, the center line of the coil spring 53 is positioned below the axis O of the connecting shaft 54, while when the cover body 19 is opened, the center line of the coil spring 53 is set. By being positioned above the axis O of the connecting shaft 54, the release state T2 in which the pressure roller 40 is released from the pressure to the fixing roller 30 according to the open / closed state of the cover body 19 with a simple configuration. It is possible to switch between the pressurized state T1 easily and in a stable state.

  The present invention is not limited to the above embodiment, and includes the following contents.

  (1) In the above embodiment, the printer 10 has been described as an example of the image forming apparatus. However, the present invention is not limited to the printer 10 as an image forming apparatus. It may be a device or the like.

  (2) In the above embodiment, the fixing roller 30 is employed as the heating member. However, the present invention is not limited to the heating roller being the fixing roller 30, and a heat source is mounted inside. Alternatively, a belt-type heating member in which a fixing belt is stretched between the heating roller and the fixing roller disposed opposite to the pressure roller 40 may be used. When such a belt-type heating member is employed, heat from the heating roller is transferred to the sheet via the fixing belt.

10 Printer (image forming device)
DESCRIPTION OF SYMBOLS 11 Apparatus main body 111 Paper conveyance path 112 Conveyance roller pair 113 Transfer roller 114 Paper discharge conveyance path 12 Image forming part 12M Magenta unit 12C Cyan unit 12Y Yellow unit 12K Black unit 121 Photosensitive drum 122 Developing device 123 Charging device 124 Exposure device 125 Transfer belt 125a Drive roller 125b Drive roller 126 Transfer roller 127 Cleaning device 13 Fixing unit 14 Paper storage unit 141 Paper tray 142 Pickup roller 15 Toner replenishment unit 151 Toner cartridge 151M Magenta cartridge 151C Cyan cartridge 151Y Yellow cartridge 151K Black cartridge 153 Toner supply unit 16 Paper discharge unit 161 Paper discharge tray 19 Cover body 191 Support shaft 1 2 Pressing plate 193 Protruding piece 194 Housing gap 20 Fixing device 21 Housing 22 Side plate 221 Inclined elongated hole 222 Stopper 23 Front installation plate 24 Rear installation plate 25 Base plate 251 Standing plate 252 Horizontal plate 253 Bracket plate 30 Fixing roller (heating member) )
31 Shaft cylinder 32 Fixing roller body 33 Gear 40 Pressure roller (pressure member)
41 Shaft cylinder 42 Elastic cylinder body 43 Cover layer 50 State change mechanism 51 V-shaped arm (operation body) 511 Arm 512 Arm 513 Locking protrusion 52 Pressing plate 521 Mounting groove 522 Locking protrusion 523 Rotation prevention protrusion 524 Rotation prevention protrusion 524 Recess 53 Coil spring (biasing member)
54 Connecting shaft 55 Operation protrusion (operation part)
L1, L2 Center line O Axis center P Paper P1 Paper bundle S1 Closed posture S2 Opened posture T1 Pressurized state T2 Released state U1 Pressurized posture U2 Released posture

Claims (3)

A fixing device for fixing the toner image to the paper while conveying the paper on which the toner image is formed by a predetermined image forming process, and the fixing device heats the toner image transferred onto the paper; In an image forming apparatus comprising: a heating member that melts; and a pressure member that changes state between a pressurized state in which the sheet is pressed toward the heating member and a released state in which the pressure is released.
A conveyance path for conveying the paper on which the toner image is formed toward the fixing device;
An openable / closable cover that covers the transport path and the fixing device;
A state change mechanism for changing the state of the pressure member between the release state and the pressure state in conjunction with the opening and closing operation of the cover body;
The state change mechanism includes an operating body that is pivotally supported around a support shaft and performs a predetermined operation according to an opening / closing operation of the cover body, and a biasing member that biases the operating body,
The operating body is urged by the urging member toward one direction in the rotation direction around the support shaft, and the pressure member is brought into a pressurized state when rotating toward the one direction side by the urging. In addition, the urging force of the urging member is weakened at the time of turning in the other direction side in the turning direction around the support shaft, and the pressurizing member is released.
The cover body has an operating body pressing plate and a return protrusion, and the operating body pressing plate rotates the operating body toward the one-direction side when the cover body is closed, and operates in the pressurized state. And an abutting contact with the return protrusion, and when the cover body is opened, the return protrusion rotates the operating body in the other direction to operate in the release state. apparatus. The state change mechanism includes a pressing plate that is linked to the operating body and presses the pressing member toward the heating member by the operation of the operating body when the cover body is closed.
In the biasing member, the pressing plate is pressed by the biasing force of the biasing member in a state where the cover body is closed, while the biasing force of the biasing member is weakened in a state where the cover body is open. The image forming apparatus according to claim 1, wherein the image forming apparatus is stretched between the operating body and the pressing plate. The operating body includes a first arm projecting upward from a base end side toward the pressurizing member side from the base end side in a state where the pressurizing member is set in a pressurizing state. A projecting second arm, and the base end side is formed by a V-shaped arm that is pivotally supported around a support shaft extending in the paper width direction perpendicular to the paper transport direction,
The first arm is provided with an operation portion that is operated by interfering with an opening / closing operation of the cover body,
The pressing plate is disposed so as to extend in a direction orthogonal to the direction in which the support shaft extends, and to be positioned directly below the support shaft,
The biasing member is stretched between a tip of the second arm and an end opposite to the end of the pressing plate that presses the pressure member,
The urging member imparts urging force to the pressing plate by the rotation of the V-arm and the pressing plate toward one direction around the support shaft of the V-arm by closing the cover body. In this state, the axis of the support shaft is disposed at a position on one side of the center line with respect to the center line of the urging member, and the cover body is opened and the other around the support shaft of the V-shaped arm. In a state where the biasing force applied to the pressing plate by the biasing member is weakened by turning in the direction, the axis of the support shaft is positioned on the one side and the center with respect to the center line of the biasing member. 3. The image forming apparatus according to claim 1, wherein a relative positional relationship is set so as to be disposed at a position on the other side of the center line on the opposite side across the line.

Images