JP5364246B2 - Image forming apparatus fixing unit structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing portion structure for an image forming apparatus, where a pressure roller and a heat roller can come in contact with each other or separate from each other, in cooperative manner with the opening/closing operation of the structure body cover, and is space-saving also, the heat roller and the pressure roller are integrally unified. <P>SOLUTION: A printer is provided with a position-changing mechanism U for changing the positions of the heat roller 11 and the pressure roller 13 of a fixing unit 9, in a cooperative manner with the opening/closing operation of the outer cover member of the printer so that the heat roller 11 and the pressure roller 13 is located in a pressurizing state release position, when opening the outer cover member, and also, so that both rollers may be located at the pressurizing position where the pressure roller 13 is brought in press contact with the heat roller 11, when outer cover member is to be closed. The position changing mechanism U is provided with a pressure arm 17 for supporting the pressure roller 13, and the pressure arm 17 is engaged with hanging holes 15b and 15c formed in a side plate 15. By the movement of the pressure arm 17, the pressure roller 13 is moved to the pressurizing position or the release position. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a fixing unit structure of an image forming apparatus including a fixing unit that performs a fixing process of a toner image on a sheet while conveying the sheet on which a toner image is formed by a predetermined image forming process.

Conventional image forming apparatuses such as copiers, printers, and the like transport paper along which a toner image is transferred by image forming processing in an image forming unit, and are disposed opposite to the upper end of the transport path. After the fixing process of the toner image on the paper is performed by the fixing device, the paper is discharged to a paper discharge tray provided on the downstream side of the fixing device.
The fixing unit of the image forming apparatus generally has a configuration of a roller and a roller, or a roller and a belt, but a so-called paper jam (jam) may occur in the fixing unit. When performing jam processing, jam processing is easy if the fixing device is disposed immediately inside the main body cover. That is, 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 paper jam clearing operation can be easily performed.

On the other hand, as described above, the fixing device includes a heating roller that performs fixing processing on the paper by heating, and a circumferential surface that is disposed opposite to the heating roller, and a peripheral surface of the fixing roller is biased by a biasing force of a predetermined biasing member. And a pressure roller to be pressed against. Then, the sheet is supplied to a nip portion between a heating roller and a pressure roller each rotating around an 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, the opening / closing operation of the main body cover is linked with the separation / contact operation between the heating roller and the pressure roller, and when the main body cover is opened by this, the pressure roller is automatically separated from the heating roller and both The pressure is released in the meantime. 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. There is an image forming apparatus that improves the workability of solving work (Patent Document 1).
JP-A-2005-37542

However, in order to pressurize the heating roller, the lever that works with the cover of the main body and the spring for pressing the pressure roller are used to press the heating roller. In this case, the lever ratio (leverage ratio) is increased, the pressure spring is strengthened, and the heating roller is pressed against the pressure roller.
The present invention has been made in view of such circumstances, and in conjunction with opening and closing of the main body cover, the pressure roller and the heating roller can be detached, space saving, and the heating roller and the pressure roller can be installed. It is an object of the present invention to provide a fixing unit structure of an image forming apparatus that can be unitized integrally.

The fixing unit structure of the image forming apparatus of the present invention includes a fixing unit that performs a toner image fixing process on a sheet while conveying the sheet on which the toner image is formed by the image forming process, and the fixing unit is transferred onto the sheet. A heating roller for fixing the heated toner image by fixing, and a pressure roller for changing the position between a pressing position for pressing the sheet toward the heating roller and a releasing position for releasing the pressure. An image including a conveyance path for conveying an image-formed sheet toward the fixing unit, an openable / closable cover member that covers the conveyance path and the fixing unit, and a side plate that supports both ends of the heating roller. In the fixing unit structure of the forming apparatus, the pressure roller is set to the release position when the cover member is opened in conjunction with the opening and closing operation of the cover member, and the pressure roller is set when the cover member is closed. A position change mechanism for changing the position of the roller to the pressure position, the position change mechanism having a pressure arm that rotatably supports the pressure roller, and the pressure arm is attached to the side plate. The pressure roller is moved to the pressure position and the release position by moving the pressure arm in the swing area, and the position changing mechanism includes A tension plate connected to the pressure arm, the pressure arm is moved to a pressure position and a release position of the heating roller according to the presence or absence of a load by the tension plate, and the position change The mechanism includes a pressure lever that is pivotally supported by the side plate and whose one end is guided by the cover member according to the opening / closing operation of the cover member, and one end that is rotatably connected to the other end of the pressure lever. And a spring disposed between the tension plate and the one end of the rod, and when the cover member is closed, the spring biases the tension plate in a compressed state Thus, the biasing direction of the spring to the tension plate and the moving direction of the pressure arm are made to coincide.
According to another aspect of the present invention, there is provided a fixing unit structure including a fixing unit that performs a toner image fixing process on a sheet while conveying the sheet on which the toner image is formed by the image forming process. The unit is a heating roller that heats and fixes the toner image transferred on the paper, and a pressure roller that changes position between a pressure position that presses the paper toward the heating roller and a release position that releases the pressure. And a conveying path that conveys the sheet on which the toner image is formed toward the fixing unit, an openable / closable cover member that covers the conveying path and the fixing unit, and supports both ends of the heating roller. In the fixing unit structure of the image forming apparatus including the side plate, the pressure roller is set to the release position when the cover member is opened in conjunction with the opening / closing operation of the cover member, and the cover member Sometimes, a position changing mechanism for changing the position of the pressure roller to the pressure position is provided, the position changing mechanism is provided with a pressure arm that rotatably supports the pressure roller, and the side plate has the heating A recess is formed to dispose the pressure arm recessed inward in the axial direction of the roller, and a pair of hook holes are formed in the recess with a space therebetween, and the pressure arm corresponds to each of the hook holes. A claw that can be inserted into the hooking hole is formed at a position where one of the hooking holes can rotate the pressure arm with the one claw as a rotation center, and the other claw is provided on the other hooking hole. The pressure arm is movably disposed within the range, and the pressure arm can be swung to change the position of the pressure arm to the pressure position and the release position of the heating roller.
The depth of the concave portion of the fixing unit structure of the image forming apparatus is larger than the thickness of the pressure arm, and the distal end portion of the pressure arm passes through the through hole formed so as to cross the concave portion of the side plate. Can be protruded in the direction.
Furthermore, the fixing unit structure of the image forming apparatus according to another aspect includes a fixing unit that performs fixing processing of the toner image on the paper while conveying the paper on which the toner image is formed by the image forming processing. A heating roller for heating and fixing the toner image transferred on the paper, and a pressure roller for changing the position between a pressure position for pressing the paper toward the heating roller and a release position for releasing the pressure. A conveying path that conveys the paper on which the toner image is formed toward the fixing unit, an openable / closable cover member that covers the conveying path and the fixing unit, and a side plate that supports both ends of the heating roller. In the fixing unit structure of the image forming apparatus, the pressure roller is set to the release position when the cover member is opened in conjunction with the opening and closing operation of the cover member, and the cover member is closed. Provided with a position change mechanism for changing the position of the pressure roller to the pressure position, the position change mechanism supported by the pressure arm for rotatably supporting the pressure roller, and the cover member supported by the side plate. A pressure lever that swings when one end is guided by the cover member in accordance with the opening / closing operation of the pressure lever, and the pressure arm swings the pressure lever at a mounting portion formed on the side plate. The cover member is slidably engaged with the attachment portion via the pressure arm, and the pressure arm moves in the swing region, thereby moving the pressure roller to the pressure position and the release position, and the cover member. the a closed, pressure lever so as to hold the cover member, the said pressure lever of the fixing part structure of the image forming apparatus, forming a boss portion protruding in the axial direction of the heating roller, the cover member The cover part Of the pressure lever forms an inclined surface abutting the closed, the boss portion to closed of the cover member can be brought into contact with the inclined surface.
In the fixing unit structure of the image forming apparatus, a hole is formed in the mounting portion of the side plate, and a claw that is inserted into the hole of the mounting portion and engages with the hole is formed in the pressure arm. It is preferable to change the position of the pressure arm between the pressure position of the heating roller and the release position with the rotation axis as the rotation axis.
The position change mechanism of the fixing unit structure of the image forming apparatus is provided with a tension plate connected to the pressure arm, and the pressure arm presses the heating roller depending on whether or not there is a load by the tension plate. It is preferable to change the position to the position and the release position.
The position changing mechanism of the fixing unit structure of the image forming apparatus includes a pressure lever that is pivotally supported by the side plate and whose one end is guided by the cover member according to an opening / closing operation of the cover member, and the pressure lever A rod having one end rotatably connected to the other end of the rod, and a spring disposed between the tension plate and the one end of the rod, and the spring is closed when the cover member is closed. In a state where the tension plate is urged in a compressed state, it is preferable that the urging direction of the spring to the tension plate coincides with the moving direction of the pressure arm.

In the fixing unit structure of the image forming apparatus of the present invention, the position changing mechanism is provided with a pressure arm that rotatably supports the pressure roller, and the pressure arm swings on a mounting portion formed on the side plate. Since the pressure roller is moved to the pressure position and the release position by moving the pressure arm in the swing region, the heating roller and the pressure roller are An integrated fixing unit can be obtained.
In the fixing unit structure of the image forming apparatus, a hole is formed in the mounting portion of the side plate, and a claw that is inserted into the hole of the mounting portion and engages with the hole is formed in the pressure arm. Since the position of the pressure arm is changed between the pressure position and the release position of the heating roller with the rotation axis as the rotation axis, the assembly becomes easy.
In the fixing unit structure of the image forming apparatus, the position changing mechanism includes a pressure lever that is pivotally supported on the side plate and is guided by the cover member in accordance with an opening / closing operation of the cover member. A rod having one end rotatably connected to the other end of the lever, and a spring disposed between the tension plate and the one end of the rod, and when the cover member is closed, In the state where the spring is compressed and the tension plate is biased, the biasing direction of the spring to the tension plate and the movement direction of the pressure arm are made to coincide with each other. Became compact. In addition, the lever (tension) ratio of the pressure arm can be reduced.

Hereinafter, a fixing unit structure of an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings.
A tandem color printer 2 (hereinafter simply referred to as “printer 2”), which is an image forming apparatus according to the present invention, will be described with reference to FIG.
The printer 2 includes a printer main body 4 that is a substantially rectangular parallelepiped image forming apparatus main body. In the printer body 4, yellow image forming means 6, magenta image forming means 8, cyan image forming means 10 and black image forming means 12 are arranged in this order from left to right in FIG. Yes. These image forming means 6, 8, 10, and 12 include image forming elements such as a photosensitive drum 14, a charger 16, an exposure device 18, a developing device 20, a primary transfer roller 22, and a cleaning device 24. . In FIG. 1, the primary transfer roller 22 is disposed on the upper side, the charger 16 is disposed on the lower side, the developing device 20 is disposed on the left side, the cleaning device 24 is disposed on the right side, and the exposure device 18 is charged. Disposed below the container 16 and the developing device 20. In FIG. 1, for simplification of illustration, the reference numerals of the image forming elements are attached only to the yellow image forming means 6. These image forming means 6, 8, 10 and 12 are juxtaposed in the above-mentioned order in the horizontal direction, in the embodiment, linearly from left to right in FIG.

  An intermediate transfer belt mechanism 26 is disposed above the image forming means 6, 8, 10 and 12. The intermediate transfer belt mechanism 26 includes a drive roller 28, a driven roller 30, and an endless intermediate transfer belt 32 wound around these rollers. A toner replenishing container (not shown) for replenishing the corresponding color toner to the developing devices 20 of the image forming units 6, 8, 10 and 12 is disposed above the intermediate transfer belt mechanism 26. ing.

  In each of the image forming units 6, 8, 10, and 12, the primary transfer roller 22 has a lower end traveling region of the intermediate transfer belt 32 with respect to the photosensitive drum 14 (extending linearly in the horizontal and horizontal directions in FIG. 1). And is pressed from above. A secondary transfer roller 34 is disposed on the drive roller 28 diagonally to the right in FIG. The secondary transfer roller 34 is brought into pressure contact with the drive roller 28 via a plurality of spring members (not shown) from the lower right side via the intermediate transfer belt 32. Since the drive roller 28 is driven to rotate counterclockwise in FIG. 1, the intermediate transfer belt 32, the driven roller 30 and the primary transfer roller 22 are also rotated counterclockwise.

  A paper feed cassette 36 is disposed below the image forming means 6, 8, 10 and 12 and at the lower end of the printer body 4. In the paper feed cassette 36, there are disposed a bottom plate 40 which is a paper placement plate supported at one end so as to be rotatable around a shaft 38, a compression coil spring 42 which pushes the other end of the bottom plate 40 upward. . The upper surface of the front end of the paper P stacked and accommodated on the bottom plate 40 is pressed against a pickup roller 44 disposed in the printer main body 4. A separation roller pair 46 is disposed on the downstream side of the pickup roller 44.

  At a position close to one side surface 4a of the printer body 4 (right end position in FIG. 1), a conveyance path 50 for conveying the paper P to form a toner image on one side of the paper P and a toner image on one side are formed. A refeed conveyance path 52 is provided for reversing the front and back of the sheet P and refeeding it to the conveyance path 50 to form a toner image on the other side. A partial region of the conveyance path 50 extends in the vertical direction along one side surface 4 a of the printer body 4. In addition, a partial area of the refeed conveyance path 52 is disposed so as to extend vertically between the one side surface 4a of the printer body 4 and the partial area of the conveyance path 50 along the one side surface 4a. ing. A paper discharge tray 54 is disposed in a partial area on the upper surface of the printer body 4.

  The conveyance path 50 extends in the vertical direction between the downstream side of the separation roller pair 46 and the upstream side of the discharge roller pair 58. A lower end region and an upper end region of the conveyance path 50 are curved so as to swell in the direction of the one side surface 4a of the printer body 4, and an intermediate region thereof extends substantially in the vertical direction along the one side surface 4a. A nip portion between the secondary transfer roller 34 and the driving roller 28 (a nip portion sandwiching the intermediate transfer belt 32) is disposed in a substantially central region of the transport path 50. Between the separation roller pair 46 and the nip portion between the secondary transfer roller 34 and the driving roller 28 in the conveyance path 50, a conveyance roller pair 60 and a registration roller pair 62 are arranged from upstream to downstream. ing. A fixing roller pair 64 and a conveying roller pair 66 are provided between the nip portion of the conveying path 50 between the secondary transfer roller 34 and the driving roller 28 and the discharge roller pair 58 from upstream to downstream. They are arranged in order. The fixing roller pair 64 includes a heating roller 11 that is heated by a heating element such as a halogen lamp, and a pressure roller 13 that is in pressure contact with the heating roller 11.

  The re-feed conveyance path 52 is curved after extending downward from the upper side of the discharge roller pair 58 of the stepped portion 56 disposed at the upper end of the printer body 4 toward the one side surface 4 a of the printer body 4. , Extending downward substantially along one side surface 4 a, inverted upward at the lower end, and merged between the conveying roller pair 60 and the registration roller pair 62 in the conveying path 50. A pair of switchback rollers 70 capable of forward / reverse rotation is disposed in the vicinity of the stepped portion 56, which is the most upstream area of the refeed conveyance path 52. Between the pair of switchback rollers 70 and the entrance of the reversal area at the lower end of the sheet refeed conveyance path 52, sheet refeed conveyance roller pairs 71, 72, 73 and 74 are arranged.

  The upper end region of the refeed conveyance path 52 is juxtaposed above the upper end area of the conveyance path 50, and the switchback roller pair 70 is disposed in the refeed conveyance path 52 at a position immediately upstream of the discharge roller pair 58. Has been. A conveyance path switching guide member 75 is provided at a position immediately upstream of the discharge roller pair 58 and between the conveyance path 50 and the refeed conveyance path 52. The transport path switching guide member 75 is a first guide position (shown by a solid line in FIG. 1) that guides the paper P transported by the transport roller pair 66 of the transport path 50 toward the discharge roller pair 58 by an actuator (not shown). Or a second guide position (a position indicated by a two-dot chain line in FIG. 1) for guiding toward the switchback roller pair 70. In a state where the transport path switching guide member 75 is switched to the first guide position (the position indicated by the solid line in FIG. 1), the switchback roller pair 70 with the rear end portion of the paper P being nipped as described later. Is reversed, the paper P is guided toward the refeed conveyance roller pair 71 in the refeed conveyance path 52.

  The cover member 82 disposed on the one side surface 4a of the printer main body 4 can be opened and closed with the re-feed conveyance path 52 as a divided portion and with a shaft 82a as a rotation center as shown in FIG. The conveyance unit 68 disposed between the conveyance path 50 and the refeed conveyance path 52 can be opened and closed with the rotation axis as the rotation center. For example, the fixing roller pair 64 is jammed. In this case, the sheet P can be pulled out from the fixing roller pair 64 by opening the transport unit 68.

  Since the printing operation itself is performed in the printer 2 as is well known, a brief description will be given below with reference to FIG. When single-sided printing is performed, the transport path switching guide member 75 is switched in advance to a first guide position (a position indicated by a solid line in FIG. 1).

  In the image forming means 6, 8, 10, and 12, the surface of the photosensitive drum 14 that is uniformly charged by the charger 16 is exposed to light by an exposure device 18 (a laser scanning unit in the embodiment). An electrostatic latent image is formed, and the electrostatic latent image is developed by the developing device 20 to become a toner image. The toner images are transferred onto the intermediate transfer belt 32 of the intermediate transfer belt mechanism 26 by the primary transfer roller 22 in such a manner that the toner images formed by the upstream image forming means 6 are sequentially superimposed and transferred. The color toner image transferred to the intermediate transfer belt 32 is transferred to the sheet P while the sheet P sent from the sheet feeding cassette 36 through the conveyance path 50 passes through the nip portion between the driving roller 28 and the secondary transfer roller 34. Transferred to one side of P. The toner image transferred to one side of the paper P is thermally fixed while passing through the fixing roller pair 64.

  The sheet P having the toner image fixed on one side is conveyed in the downstream direction by the conveying roller pair 66. The sheet P transported by the transport roller pair 66 is guided toward the discharge roller pair 58 by the transport path switching guide member 75, and one side of the toner image fixed on the paper discharge tray 54 is directed downward by the discharge roller pair 58. It is discharged in a so-called face-down state.

Next, details of the fixing unit 9 according to the present invention will be described.
FIG. 3 shows the fixing unit 9 in which the fixing roller pair 64 is assembled. The fixing unit 9 is provided between side plates 15 that are arranged at both ends with a predetermined interval. The side plate 15 has a plate surface that extends in a direction perpendicular to the axial direction of the heating roller 11. Is supported rotatably. The fixing unit 9 includes a position adjusting member U that pressurizes the heating roller 11. The structure of the position adjusting member U is substantially symmetrical with respect to the left and right, and the configuration of the position adjusting member U will be described using the portion of the fixing unit 9 located on the left side in FIG.

4 is a side view of the position adjusting member U viewed from the outside of the fixing unit 9, FIG. 5 is a perspective view of the position adjusting member U viewed from the inside of the fixing unit 9, and FIG. FIG. 7 is a perspective view of the position adjustment member U from which the coil spring 21) is omitted as viewed from the outside of the fixing unit 9. FIG. 7 is a position adjustment member in which some components (tension plate 19, coil spring 21, pressure lever 25) are omitted. FIG. 6 is a perspective view of U as viewed from the inside of the fixing unit 9.
4 to 7, the position adjustment member U includes a pressure arm 17, a tension plate 19, a coil spring 21, a rod 23, and a pressure lever 25. The pressure arm 17 is arranged so as to be parallel to the side plate 15, and a support plate portion 17 a that rotatably supports the end portion of the pressure roller 13 is formed on one end side, and is formed on the upper edge portion of the tip end portion 17 e. Grooves 17b are formed on the lower side, and claws 17c and 17d that are bent toward the side plate are formed on the upper and lower portions of the support plate.

On the other hand, the side plate 15 is formed with a recess 15a that is recessed inward in the axial direction of the heating roller 11, and the recess 15a is formed with hook holes 15b and 15c spaced apart from each other in the vertical direction. The above-mentioned claws 17c and 17d are arranged at positions corresponding to the hooking holes 15b and 15c. The pressure arm 17 is configured such that the lower claw 17d can move within the range of the hook hole 15c with the upper claw 17c as a rotation center, and the tip end portion 17e can swing.
The depth of the concave portion 15a is larger than the thickness of the pressure arm 17, and the distal end portion 17e of the pressure arm 17 goes outward of the side plate 15 through a through hole 15e formed so as to cross the concave portion 15a of the side plate 15. It is protruding. As shown in FIG. 7, a projecting plate 27 a that is covered with the cover 27 on the outer surface of the side plate 15 and is formed on the inner surface of the cover 27 and projects in the axial direction of the heating roller 11 projects to the side surface of the pressure arm 17. It plays the role of retaining the pressure arm 17.

A tension plate 19 having an L-shaped cross section is engaged with the groove 17 b formed in the pressure arm 17. As shown in FIG. 5, the tension plate 19 forms a vertical plate portion 19a and a horizontal plate portion 19b, and a long hole 19c that is long in the vertical direction is formed on the upper end side of the vertical plate portion 19a. The groove 17b of the pressure arm 17 is fitted into the edge of 19c. A loose fitting hole 19 d is formed in the horizontal plate portion 19 b of the tension plate 19. A rod 23 whose axis is arranged in the vertical direction is inserted through the loose fitting hole 19d.
The rod 23 forms a connecting hole 23a (see FIG. 7) constituting a connecting portion with the pressure lever 25 at the upper end, and the pressure lever 25 is pivotally supported by the connecting hole 23a. A circular spring seat 23b is formed at the lower portion of the connecting hole 23a so as to protrude outward from the axis of the rod 23. Between the spring seat 23b and the lateral plate 19b of the tension plate 19, a coil spring 21 is formed. Is arranged.
The lower end side of the rod 23 includes a loose fitting hole 19d of the tension plate 19 described above, and a restriction hole 15g formed in a restriction plate portion 15f bent from the side plate 15 toward the inner side in the axial direction of the heating roller 11 with the tip end portion. Are penetrated in a loosely fitted state.

  The pressure lever 25 is supported by a bearing 15 h (see FIG. 7) formed on the side plate 15 so that the swing shaft 25 a can swing. The swing shaft 25 a passes through the shaft hole 25 d of the pressure lever 25. It is connected to the left right plate 15. A columnar boss portion 25b that protrudes outward in the axial direction of the heating roller 11 is formed at one end portion of the pressure lever 25, and the connecting hole 23a (see FIG. 7) through the connecting shaft 29, the pressure lever 25 and the rod 23 are connected. Thus, the position of the pressure lever 25 can be switched.

  The cover member 82 disposed on the one side surface 4a of the printer main body 4 shown in FIG. 1 can be opened and closed with the refeed conveyance path 52 as a dividing portion and the shaft 82a as a rotation center. FIG. 9 shows a state where the cover member 82 is closed, and FIG. 10 shows a state immediately before the cover member 82 is closed. A guide portion that engages with the boss portion 25 b of the pressure lever 25 is formed at the upper end portion of the cover member 82. The guide portion is formed by a front wall 82b facing in the vertical direction and a rear wall 82c having an inclined surface. When the cover member 82 is closed, the boss portion 25b of the pressure lever 25 and the rear wall 82c are in contact with each other. When the cover member 82 is opened from this state, the rear wall 82c moves forward on the arrow a side and the boss portion 25b is pressed against the rear wall 82c, whereby the pressure lever 25 rotates and the boss portion 25b is moved. One end of the provided pressure lever 25 moves forward (state shown in FIG. 8). When the cover member 82 moves from the open position to the closed position, the boss portion 25b comes into contact with the front wall 82b of the cover member 82 as shown in FIG. 25b is configured so that one end portion of the pressure lever 25 moves rearward by being pressed to the arrow b side as it is (state of FIG. 5).

Next, the operation of the embodiment of the present invention will be described.
The transition operation between the pressure position and the release position of the pressure roller 13 of the printer 2 will be described. When the cover member 82 is in the closed position and the printer 2 is in the operating state, the pressure roller is connected to the heating roller 11 of the fixing unit 9. 13 is in the pressing position where it is in pressure contact (state shown in FIG. 5). When the cover member 82 is in the open position, the pressure applied to the heating roller 11 by the pressure roller 13 is released, and the pressure roller 13 is moved to the release position (state shown in FIG. 8). In the pressure position of the pressure roller 13 with the cover member 82 in the closed position, the coil spring 21 is compressed and the tension plate 19 is in the lower position as shown in FIG.

  When the cover member 82 is opened from the closed position of the cover member 82 shown in FIGS. 1 and 9, the rear wall 82c of the cover member 82 presses the boss portion 25b of the pressure lever 25 toward the front side of the arrow a. As a result, one end of the pressure lever 25 rotates forward about the swing shaft 25a as a rotation axis. Since the rod 23 penetrates both the upper loose fitting hole 19d and the lower regulating hole 15g so as to loosely fit, the lower end portion of the rod 23 is made to penetrate the holes 15g and 19d. From the upright posture shown in FIG. 5, the posture is inclined while sliding obliquely upward as shown in FIG. 8. That is, when the rod 23 is tilted and moved in the direction shown by the arrow c from the state shown in FIG. 5 and the extension shaft of the rod 23 and the swing shaft 25a are in a straight line, the rod 23 is temporarily moved to the lower position. Move to. Thereafter, the rod 23 is further inclined to the arrow c side, so that the rod 23 slides obliquely upward as shown by the solid line in FIG. 11, and the coil spring 21 in the compressed state extends.

  At this time, when the coil spring 21 extends along with the slide of the rod 23 upward, the horizontal plate 19b of the tension plate 19 urged downward by the coil spring 21 is relative to the regulating plate portion 15f. Move away upward. Then, the end of the pressure arm 17 in which the groove 17b is engaged with the long hole 19c of the tension plate 19 is raised. Then, the end of the pressure arm 17 rises upward from the position shown in FIG. 4, and the pressure roller 13 pivotally supported by the rotation of the pressure arm 17 moves from the pressure position to the release position. Then, the pressure of the heating roller 11 is released (see FIG. 8). Accordingly, during the jam processing, the conveyance path 68 shown in FIG. 1 can be opened, and the sheet can be easily pulled out from the fixing unit 9.

When the cover member 82 is closed, as shown in FIG. 10, the front wall 82b of the cover member 82 presses the boss portion 25b of the pressure lever 25 to the rear side of the arrow b. As a result, the one end of the pressure lever 25 rotates rearward with the swing shaft 25a as the rotation axis. The rod 23 changes from the inclined posture shown in FIG. 8 to the upright posture shown in FIG. That is, the rod 23 moves from the state shown in FIG. 8 in the direction indicated by the arrow e, and the coil spring 21 is compressed by sliding the rod 23 downward.
Then, the horizontal plate 19b of the tension plate 19 is urged downward by the coil spring 21, approaches relatively to the regulating plate portion 15f formed on the side plate 15, and moves downward. Since the slot 17b of the pressure arm 17 is engaged with the elongated hole 19c of the tension plate 19, the tip end portion 17e of the pressure arm 17 is lowered. Then, the pressure roller 13 pivotally supported by the rotation of the pressure arm 17 moves from the release position to the pressure position, the heating roller 11 is pressurized by the pressure roller 13, and the printer 2 can be operated. It becomes a state.

  As described above, in the present embodiment, the heating arm 11 is rotatably supported on the side plate 15, and the pressure arm 17 that supports the pressure roller 13 is attached to the side plate 15. We are trying to make it. Further, the pressure arm 17 is rotated by winding the rod 23 with the coil spring 21 and pressing the tension plate 19 with this compression spring. In order to swing the distal end portion 17e of the pressure arm 17, the swinging direction of the distal end portion 17e and the moving direction of the rod 23 and the coil spring 21 are substantially coincided with each other. The size of the fixing unit 9 can be made compact. Further, as shown in FIG. 5, when the tension plate 19 swings the pressure arm 17 at the pressure position of the pressure roller 13, the coil is moved with respect to the swinging direction of the pressure arm 17. The biasing direction of the tension plate 19 by the spring 21 is made coincident (both downward), and the tension plate 19 (coil spring 21) applies a load in a tangential direction with respect to the swinging direction of the pressure arm 17. Therefore, since a large force can be applied to the pressure arm 17 with a small force, the lever ratio of the pressure arm 17 can be reduced.

As mentioned above, although it demonstrated in detail, referring an accompanying drawing based on embodiment of this invention, this invention is not limited to the said embodiment, Furthermore, various other various, without deviating from the scope of the present invention. Can be modified or modified.
For example, in the above-described embodiment, the pressure arm 17 is rotated by being engaged with the hook hole 15b of the side plate 15 so that the claw 17c of the pressure arm 17 is hooked. 15 may be pivotally supported. However, it takes time to incorporate the pressure arm 17. The other hook hole 15c and the claw 17 may be omitted.

1 is a cross-sectional view of a printer that employs a fixing unit structure of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the printer of FIG. 1 with an outer cover opened. FIG. 2 is a perspective view of a fixing unit of the image forming apparatus disposed in FIG. 1. FIG. 4 is a side view showing a state where a pressure roller of the fixing unit in FIG. 3 is in a pressure position. FIG. 4 is a perspective view of a side plate portion of the fixing unit viewed from the inside in a state where a pressure roller of the fixing unit in FIG. 3 is in a pressure position. FIG. 4 is a perspective view of a side plate portion of a fixing unit (a tension plate and a coil spring are omitted) viewed from the outside in a state where a pressure roller of the fixing unit in FIG. 3 is in a pressure position. FIG. 4 is a perspective view of a state in which a side plate of the fixing unit (a tension plate, a coil spring, and a pressure lever are omitted) of FIG. 3 is viewed from the inside. FIG. 4 is a perspective view of a side plate portion of the fixing unit viewed from the inside in a state where a pressure roller of the fixing unit in FIG. 3 is in a release position. FIG. 2 is a cross-sectional view of a fixing unit in a state where an outer cover of the printer of FIG. 1 is in a closed position. FIG. 2 is a cross-sectional view of a fixing unit immediately before an outer cover of the printer of FIG. 1 is closed from an open position. FIG. 5 is a side view for explaining the operation of the position adjustment mechanism in a state in which the fixing unit of FIG. 4 is viewed from the side direction.

Explanation of symbols

2 Printer 9 Fixing unit 11 Heating roller 13 Pressure roller 15 Side plate 15b, 15c Hooking hole 15d Stepped portion 17 Pressure arm 17b Groove 17c, 17d Claw 19 Tension plate 19a Vertical plate 19b Horizontal plate 19c Long hole 21 Coil spring 23 Rod 25 Pressure lever 25b Boss part 52a Outer re-feed conveyance path 82 Outer cover

Claims (7)

A fixing unit for fixing the toner image to the paper while conveying the paper on which the toner image is formed by the image forming process;
The fixing unit is a heating roller that heats and fixes the toner image transferred on the sheet, and a pressure position that pressurizes the sheet toward the heating roller and a release position that releases the pressure. A pressure roller,
A conveyance path that conveys the sheet on which the toner image is formed toward the fixing unit; an openable / closable cover member that covers the conveyance path and the fixing unit; and a side plate that supports both ends of the heating roller. In the fixing unit structure of the image forming apparatus,
In conjunction with the opening and closing operation of the cover member, there is provided a position change mechanism that moves the pressure roller to the release position when the cover member is opened and changes the pressure roller to the pressure position when the cover member is closed. ,
The position change mechanism includes a pressure arm that rotatably supports the pressure roller, the pressure arm is slidably engaged with a mounting portion formed on the side plate, and the pressure arm is By moving the swing region, the pressure roller is moved to the pressure position and the release position,
The position change mechanism is provided with a tension plate connected to the pressure arm, and the pressure arm is positioned at the pressure position and the release position of the heating roller depending on the presence or absence of a load by the tension plate. Change
Further, the position changing mechanism includes a pressure lever that is pivotally supported by the side plate and whose one end is guided by the cover member according to the opening / closing operation of the cover member, and one end at the other end of the pressure lever. A rod connected rotatably, and a spring disposed between the tension plate and the one end of the rod,
When the cover member is closed, the biasing direction of the spring to the tension plate and the moving direction of the pressure arm are made to coincide with each other while the tension plate is biased in the compressed state. A fixing unit structure of an image forming apparatus. A fixing unit for fixing the toner image to the paper while conveying the paper on which the toner image is formed by the image forming process;
The fixing unit is a heating roller that heats and fixes the toner image transferred on the sheet, and a pressure position that pressurizes the sheet toward the heating roller and a release position that releases the pressure. A pressure roller,
A conveyance path that conveys the sheet on which the toner image is formed toward the fixing unit; an openable / closable cover member that covers the conveyance path and the fixing unit; and a side plate that supports both ends of the heating roller. In the fixing unit structure of the image forming apparatus,
In conjunction with the opening and closing operation of the cover member, there is provided a position change mechanism that moves the pressure roller to the release position when the cover member is opened and changes the pressure roller to the pressure position when the cover member is closed. ,
The position change mechanism is provided with a pressure arm that rotatably supports the pressure roller,
The side plate is formed with a recess for disposing the pressure arm that is recessed inward in the axial direction of the heating roller, and a pair of hook holes are formed in the recess with a space therebetween. A nail that can be inserted into the hooking hole is formed at a position corresponding to each of the hooking holes,
One hook hole allows the pressure arm to turn around one claw as a rotation center,
The other claw is arranged so as to be movable within the range of the other hooking hole, and by allowing the pressure arm to swing, the pressure arm is moved to the pressure position and the release position of the heating roller. A fixing unit structure of an image forming apparatus, wherein the position is changed.   The depth of the concave portion is larger than the thickness of the pressure arm, and the tip end portion of the pressure arm protrudes outward from the side plate through a through hole formed so as to cross the concave portion of the side plate. A fixing unit structure of the image forming apparatus according to claim 1. A fixing unit for fixing the toner image to the paper while conveying the paper on which the toner image is formed by the image forming process;
The fixing unit heats and fixes the toner image transferred on the paper;
A pressure roller that pressurizes the sheet toward the heating roller and a pressure roller that changes position between a release position where the pressure is released,
A conveyance path that conveys the sheet on which the toner image is formed toward the fixing unit; an openable / closable cover member that covers the conveyance path and the fixing unit; and a side plate that supports both ends of the heating roller. In the fixing unit structure of the image forming apparatus,
In conjunction with the opening and closing operation of the cover member, there is provided a position change mechanism that moves the pressure roller to the release position when the cover member is opened and changes the pressure roller to the pressure position when the cover member is closed. ,
The position change mechanism swings by a pressure arm that rotatably supports the pressure roller, and an end portion that is pivotally supported by the side plate and guided by the cover member according to an opening / closing operation of the cover member. And a pressure lever to
The pressure arm engages with a mounting portion formed on the side plate so as to be swingable to the mounting portion through swinging of the pressure lever, and the pressure arm moves in the swinging region. By moving the pressure roller to the pressure position and the release position,
When the cover member is closed, the pressure lever holds the cover member ,
The pressure lever is formed with a boss projecting in the axial direction of the heating roller, and the cover member is formed with an inclined surface with which the pressure lever abuts when the cover member is closed. A fixing portion structure of an image forming apparatus , wherein the boss portion is brought into contact with an inclined surface when closed . A hole is formed in the mounting portion of the side plate, and a claw that is inserted into the hole of the mounting portion and engages with the hole is formed in the pressure arm. fixing part structure of an image forming apparatus according to claim 1 or 4, characterized in that so as to position change in pressing position and the release position of the heating roller. The position change mechanism is provided with a tension plate connected to the pressure arm,
4. The fixing of an image forming apparatus according to claim 2, wherein the pressure arm is moved to a pressure position and a release position of the heating roller depending on whether a load is applied by the tension plate. Part structure. The position change mechanism includes a pressure lever that is pivotally supported by the side plate and whose one end is guided by the cover member according to the opening and closing operation of the cover member, and one end that rotates to the other end of the pressure lever. A rod that can be connected, and a spring disposed between the tension plate and the one end of the rod;
When the cover member is closed, the biasing direction of the spring to the tension plate and the moving direction of the pressure arm are made to coincide with each other while the tension plate is biased in the compressed state. The fixing unit structure of the image forming apparatus according to claim 6 .

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