JP6048097B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an electrophotographic image forming apparatus.

  2. Description of the Related Art An electrophotographic image forming apparatus such as a laser beam printer is configured to form an image on a recording sheet by thermally fixing the toner image transferred to the recording paper (recording sheet). Such an image forming apparatus includes, for example, an image forming cartridge having a pair of fixing rollers for thermally fixing a toner image, a photosensitive drum on which the toner image is formed, and a photosensitive member as disclosed in Patent Document 1. An optical system unit for irradiating the body drum with laser, a sheet storage unit for holding the recording sheet, and the like are provided.

JP-A-6-43702

  Incidentally, in the image forming apparatus of Patent Document 1, when a recording sheet is jammed in the image forming process, the image forming cartridge is arranged by opening the lid member provided on the upper side of the apparatus main body and removing the image forming cartridge. The recording sheet can be removed from the space. However, when the jammed recording sheet is sandwiched between the fixing rollers, when the recording sheet is removed, the recording sheet comes out of contact with a wall around the fixing roller and is bent at an acute angle. Therefore, the recording sheet may be broken at the edge of the wall and the fragments may remain in the apparatus main body.

  The present invention has been made in view of the above background, and an object thereof is to provide an image forming apparatus capable of suppressing breakage of a recording sheet when a jammed recording sheet is removed.

In order to achieve the above object, an image forming apparatus of the present invention includes an apparatus main body having an opening, a process cartridge that can be attached to and detached from the apparatus main body through the opening, a heating member, and a pressure member. A fixing unit configured to thermally fix the developer image on a recording sheet passing between the pressure members, and extending in a process cartridge mounting direction toward the fixing unit and the process cartridge. A mounting guide configured to guide the mounting of the cartridge, and when the recording sheet is jammed, the process cartridge is removed from the main body of the apparatus, and the recording sheet held between the heating member and the pressure member is It is configured to be removed from the opening.
The downstream end of the mounting guide in the mounting direction contacts the recording sheet when the recording sheet is removed from the opening, and the contact portion is formed in a curved surface having a predetermined width in the width direction of the recording sheet.

  According to such a configuration, when removing the jammed recording sheet from the opening of the apparatus main body, the recording sheet is pulled out while being guided by the contact portion formed in the curved shape of the mounting guide. Can be suppressed.

  In the image forming apparatus described above, the mounting guide is inclined toward the side closer to the fixing unit with respect to the direction connecting the portion where the developer image is transferred to the process cartridge and the heating member and the pressure member. It can be configured.

  In such a configuration, when the jammed recording sheet is removed from the opening, the recording sheet is bent at an acute angle along the contact portion of the mounting guide and easily broken, but the contact portion is formed in a curved surface shape. Thus, breakage of the recording sheet can be effectively suppressed.

  The above-described image forming apparatus can be configured to include a pre-fixing guide configured to guide the recording sheet sent from the process cartridge toward the heating member and the pressing member.

  According to this, since the recording sheet sent out from the process cartridge can be favorably guided between the heating member and the pressurizing member, the occurrence of jam itself can be suppressed.

  In the above-described image forming apparatus, the fixing unit includes an electronic component and a frame member that supports the heating member, and the mounting guide is formed as a separate member from the frame member, and is configured to cover the electronic component. Can do.

  According to this, the electronic component can be protected by the mounting guide. In addition, since the mounting guide and the frame member that supports the heating member are formed as separate members, heat is transmitted from the frame member to the mounting guide that the user may touch when removing the jammed recording sheet. Can be suppressed.

  In the image forming apparatus described above, the mounting guide can be configured to be detachable from the frame member.

  According to this, since the mounting guide can be assembled to the frame member after the electronic component is assembled to the frame member, it is easy to arrange the electronic component in a state covered with the mounting guide.

  The above-described image forming apparatus includes a post-fixing guide configured to guide the surface on the mounting guide side of the recording sheet after heat fixing toward the outside of the apparatus main body, and the post-fixing guide is formed integrally with the mounting guide. It can be set as the structure currently made.

  According to this, the number of parts can be reduced, and the number of steps for assembling the apparatus can be reduced.

  According to the present invention, it is possible to suppress breakage of the recording sheet when the jammed recording sheet is removed (during jam processing).

1 is a cross-sectional view illustrating a schematic configuration of a laser printer as an example of an image forming apparatus according to an embodiment of the present disclosure. It is sectional drawing of a laser printer when a top cover exists in an open position. FIG. 2 is an enlarged cross-sectional view illustrating a configuration of a fixing device and a periphery of the fixing device. 2 is a plan view of the fixing device. FIG. 4A is a perspective view of the fixing device, and FIG. 4A is a diagram illustrating when the movable guide portion of the second conveyance guide is in the first position, and FIG. 5B is a diagram illustrating the time when the movable guide portion is in the second position. It is explanatory drawing of the guide rib provided in the 2nd conveyance guide. FIG. 6 is an enlarged perspective view of the fixing device when a movable guide portion is in a second position. 2A is an enlarged plan view of the fixing device, and FIG. 3A is a diagram showing a movable guide portion in a first position, and FIG. 2B is a diagram showing a movable guide portion in a second position. It is a figure which shows the structure of a movable guide part and a holding | maintenance part, (a) which shows when a movable guide part exists in a 1st position, and (b) which shows when a movable guide part exists in a 2nd position. . It is the perspective view (a) of the frame member and roof member with which the cover member was assembled | attached, and B arrow view (b) of (a). It is the perspective view of a cover member and a frame member seen from the lower side. It is explanatory drawing when a cover member is assembled | attached to a frame member. It is a perspective view which shows the state which assembled | attached the cover member to the frame member. FIG. 4 is an enlarged cross-sectional view illustrating a configuration around a fixing device when a top cover is in an open position.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings as appropriate. In the following description, the direction will be described with reference to a user who uses the laser printer 1 as an example of the image forming apparatus. That is, the left side in FIG. 1 is “front”, the right side is “rear”, the front side of the page is “right”, and the back side is “left”. Also, the vertical direction in FIG.

First, a schematic configuration of the laser printer 1 according to the present embodiment will be described.
As shown in FIG. 1, the laser printer 1 includes a main body frame 10 as an example of an apparatus main body, and a top cover 20 (cover) disposed on the upper portion of the main body frame 10. The top cover 20 is provided so as to move with respect to the main body frame 10, specifically, to rotate about the rear side as a fulcrum. As a result, the top cover 20 is located between the open position formed in the upper portion of the main body frame 10 shown in FIG. 2 and the closed position shown in FIG. And can be opened and closed.

  The laser printer 1 includes a sheet feeding unit 30, an exposure device 40, a process cartridge 50 (image forming unit), a fixing device 60 (fixing unit), and a sheet S as an example of a recording sheet. A discharge unit 90 configured to discharge to the outside of the frame 10 is mainly provided.

  The paper feed unit 30 is provided at a lower portion in the main body frame 10 and mainly includes a paper feed tray 31 for storing the paper S and a paper feed mechanism 32. The sheets S in the sheet feeding tray 31 are separated one by one by the sheet feeding mechanism 32 and supplied to the process cartridge 50.

  The exposure device 40 is provided on the upper front side of the paper feeding unit 30 and includes a laser light source, a polygon mirror, a lens, and the like (not shown). The laser light emitted from the laser light source based on the image data is reflected from the polygon mirror or passes through the lens, and is emitted from the exposure device 40 (refer to the chain line), and is high-speed on the surface of the photosensitive drum 51. Scan.

  The process cartridge 50 can be attached to and detached from the main body frame 10 through the opening 11 of the main body frame 10 when the top cover 20 is rotated to the open position (see FIG. 2). It is arranged on the upper rear side of the paper part 30. The process cartridge 50 is configured to transfer a toner image as a developer image onto the paper S, and includes a photosensitive drum 51, a charger 52, a transfer roller 53, a developing roller 54, a layer thickness regulating blade (not shown), A toner storage unit that stores toner as an example of a developer is provided. In the process cartridge 50, the surface of the photosensitive drum 51 is uniformly charged by the charger 52 and then exposed by the laser beam from the exposure device 40, so that the static on the basis of the image data is formed on the photosensitive drum 51. An electrostatic latent image is formed. Then, the toner in the toner container is supplied to the photosensitive drum 51 by the developing roller 54, whereby the electrostatic latent image is visualized and a toner image is formed on the photosensitive drum 51. Thereafter, the paper S supplied from the paper supply unit 30 passes between the photosensitive drum 51 and the transfer roller 53, whereby the toner image on the photosensitive drum 51 is transferred onto the paper S.

  The fixing device 60 is disposed above the process cartridge 50 attached to the main body frame 10. The fixing device 60 is configured to thermally fix the toner image transferred onto the paper S, and mainly includes a heating rotator 61 (heating member) and a pressure rotator 62 (pressure member). I have. In the fixing device 60, the sheet S on which the toner image is transferred passes between the heating rotator 61 and the pressure rotator 62, so that the toner image is thermally fixed on the sheet S.

  The discharge unit 90 is provided on the top cover 20 and is disposed obliquely above and in front of the heating rotator 61 when the top cover 20 is in the closed position. The discharge unit 90 mainly includes a discharge roller 90R. The sheet S on which the toner image has been thermally fixed is discharged out of the main body frame 10 by the discharge roller 90R and stacked on the discharge tray 21 formed on the top cover 20.

Next, the structure relevant to the characteristic part of this invention is demonstrated in detail.
As shown in FIG. 3, in addition to the heating rotator 61 and the pressure rotator 62, the fixing device 60 includes a casing 63 that supports the heating rotator 61 and the pressure rotator 62, and a sheet from the heating rotator 61 to the sheet. A peeling member 64 configured to peel S and a thermistor 65 as an electronic component are provided.

  The heating rotator 61 is a hollow metal roller (heating roller), in which a halogen lamp 61H is disposed, and heat from the halogen lamp 61H is transferred to the toner on the paper S while contacting the paper S, thereby making the paper The toner on S is configured to be heated. The pressure rotator 62 is a roller (pressure roller) in which an elastic layer is provided around the cored bar, and is disposed obliquely above the heating rotator 61. One of the heating rotator 61 and the pressure rotator 62 is driven to rotate when a driving force is transmitted from a motor (not shown), and the other is driven to rotate by a frictional force. 62 is configured to convey the sheet S to and from 62. In the present invention, the heating rotator is not limited to the heating roller, and may be, for example, an endless belt having flexibility. Further, the pressure rotating body is not limited to the pressure roller, and may be, for example, a belt-shaped pressure member.

  The peeling member 64 is a member whose tip is formed in a substantially acute angle when viewed from the side, and is attached to the casing 63 (specifically, the frame member 300) so that the tip is in contact with the upper part of the outer peripheral surface of the heating rotator 61. It is attached. As shown in FIG. 4, four such peeling members 64 are arranged in the left-right direction that is the width direction of the paper S.

  Returning to FIG. 3, the thermistor 65 is a non-contact temperature sensor configured to detect the temperature of the heating rotator 61. As an example, the thermistor 65 is provided with a thermistor element on a film that absorbs infrared rays formed of polyimide or the like. The thermistor 65 is disposed on the opposite side of the pressure rotator 62 with the heating rotator 61 interposed therebetween, and is opposed to the outer peripheral surface of the heating rotator 61 while being separated from the heating rotator 61. More specifically, the thermistor 65 is in a horizontal plane PL1 passing through the rotation center 61A of the heating rotator 61 in a posture when the fixing device 60 is used, specifically, in a posture when the fixing device 60 is attached to the main body frame 10. Further, it is disposed on the upstream side in the rotation direction of the heating rotator 61 with respect to the vertical plane PL2 passing through the rotation center 61A and closer to the vertical plane PL2 than the horizontal plane PL1. Information on the temperature detected by the thermistor 65 is output to a control device 72 (see FIG. 4), which will be described later, and is used to control the halogen lamp 61H (fixing device 60).

  The casing 63 is a member constituting the frame of the fixing device 60, and the sheet S after heat fixing is directed to the outside of the main body frame 10, more specifically, between the heating rotator 61 and the pressure rotator 62. A conveyance path P configured to guide the conveyed sheet S toward the discharge unit 90 is formed. As a result, at least a part of the conveyance path to be formed in the main body frame 10 can be omitted, so that the cost of the laser printer 1 can be reduced.

  The conveyance path P constitutes the lower side of the path, the first conveyance guide 100 configured to guide the image forming surface S1 that is the surface on which the toner image of the paper S is transferred, and the upper side of the path. The second conveyance guide 200 and the top cover 20 are configured mainly so as to guide the back surface S2 of the sheet S opposite to the image forming surface S1. The first transport guide 100, the second transport guide 200, and the top cover 20 have guide ribs 22, 111, projecting into the transport path P and extending along the transport direction of the sheet S on the surfaces constituting the path, respectively. A plurality of 211 (see FIG. 6) and 221 are arranged in the left-right direction. In the following description, the transport direction of the paper S is simply referred to as “transport direction”.

  In the first conveyance guide 100, a guide surface 110 provided with guide ribs 111 extends along the front-rear direction from the upper side of the heating rotator 61 toward the discharge unit 90, and obliquely downward toward the downstream side in the conveyance direction. It is inclined to. The first transport guide 100 is provided with a guide roller 120 at the end on the upstream side in the transport direction.

  The guide roller 120 is arranged so that the paper S passes through it, and is configured to be driven and rotated by a frictional force with the paper S due to the conveyance of the paper S. As shown in FIG. 4, such guide rollers 120 are arranged one by one between adjacent peeling members 64, and a plurality, specifically three, are provided side by side in the left-right direction. In the laser printer 1, by having the guide roller 120, the sheet S can be favorably transported in the transport path P. Further, since the guide roller 120 is driven and rotated by the conveyance of the paper S, the rubbing of the image forming surface S1 can be suppressed.

Here, the positional relationship between the guide roller 120 and the discharge roller 90R will be described.
As shown in FIG. 3, the discharge roller 90R includes a first discharge roller 91, a second discharge roller 92 disposed obliquely in front of the first discharge roller 91, and a downstream side of the first discharge roller 91 in the transport direction. The first discharge roller 91 is transmitted to the gear 92G (see FIG. 4) provided at one end of the rotation shaft 92A of the second discharge roller 92. And the second discharge roller 92 and between the second discharge roller 92 and the third discharge roller 93.

  A nip position N1 between the first discharge roller 91 and the second discharge roller 92 is disposed below a horizontal plane PL3 that is in contact with the upper end of the guide roller 120. Accordingly, the laser printer 1 can be downsized in the vertical direction as compared with the configuration in which the nip position N1 is disposed above the horizontal plane PL3.

  Further, since the nip position N1 is disposed below the horizontal plane PL3, the sheet S is guided to the nip position N1 while being inclined obliquely downward from the guide roller 120, and the first discharge roller 91 and the second discharge roller 92. In this embodiment, after passing between the first discharge roller 91 and the second discharge roller 92, the sheet S is moved to the nip position N1 by the third discharge roller 93. It will be discharged above the rush angle. Thereby, the stacking amount of the discharged paper S on the paper discharge tray 21 can be increased as compared with the configuration in which the paper S is discharged downward. Further, since the discharge roller 90R is composed of three rollers, curling in the direction in which the leading edge and the trailing edge of the sheet S tend to approach each other can be suppressed.

  As shown in FIG. 4, a plurality of, specifically two, discharge rollers 90 </ b> R are provided in the left-right direction, similarly to the guide roller 120. By providing a plurality of guide rollers 120 and discharge rollers 90R side by side in this way, the cost of the laser printer 1 can be reduced compared to the case where each roller is a single roller that is long in the width direction. Can do.

  The rightmost guide roller 120 and the right discharge roller 90R are disposed at the same position in the left-right direction, and the leftmost guide roller 120 and the left discharge roller 90R are disposed at the same position in the left-right direction. Accordingly, the guide roller 120 positioned on the upstream side in the transport direction of the discharge roller 90R can be operated effectively, so that the paper S can be transported better and the rubbing of the image forming surface S1 can be further suppressed. it can.

  As shown in FIG. 3, the second transport guide 200 is disposed above the heating rotator 61 so as to face the upstream portion of the first transport guide 100 including the guide roller 120 in the transport direction, and above the heating rotator 61. It is comprised so that it may extend toward the discharge part 90 from. A downstream end 201 that is an end on the downstream side in the transport direction of the second transport guide 200 is disposed at a predetermined interval in the front-rear direction with the second discharge roller 92 of the discharge unit 90. Thereby, the second conveyance guide 200 forms a rear portion of the upper side of the conveyance path P.

  On the other hand, the top cover 20 forms a front portion of the upper side of the transport path P. The guide rib 22 provided on the top cover 20 is disposed between the downstream end 201 and the second discharge roller 92 when the top cover 20 is in the closed position, and the first conveyance guide 100 and the second conveyance guide 200. The rear surface S2 of the sheet S conveyed from between is guided to the discharge unit 90, more specifically, toward the nip position N1. In the present embodiment, since the discharge portion 90 and the guide rib 22 are both provided on the top cover 20, the positional accuracy of the discharge portion 90 and the guide rib 22 can be improved, and the sheet S is favorably directed toward the nip position N1. Can guide.

  When the top cover 20 is in the closed position shown in FIGS. 1 and 3, the top cover 20 covers the portion between the downstream end 201 and the discharge unit 90 and the second transport guide 200, and is opened as shown in FIGS. 2 and 14. When in the position, the portion between the downstream end 201 and the discharge unit 90 and the second conveyance guide 200 are opened (exposed). Thereby, by rotating the top cover 20 to the open position, a part between the downstream end 201 and the discharge part 90, that is, a part of the transport path P can be exposed, and the second transport It becomes possible to operate the movable guide 220 described later by exposing the guide 200.

  As shown in FIG. 4, the second transport guide 200 is provided on the fixed guide portion 210 configured to guide the left and right end portions of the back surface S2 of the paper S indicated by the chain line, and on the fixed guide portion 210 in the left and right direction. It has a movable guide part 220 indicated by a thick two-dot chain line provided adjacently. More specifically, the second transport guide 200 of the present embodiment includes a first fixed guide portion 210A configured to guide one end portion in the left-right direction of the back surface S2 of the paper S as the fixed guide portion 210, and the other end. And a movable guide portion 220 is disposed between the first fixed guide portion 210A and the second fixed guide portion 210B, and each fixed guide portion is configured to guide each portion. It is provided adjacent to 210A and 210B.

  As shown in FIGS. 5A and 5B, the fixed guide portion 210 is immovable with respect to the housing 63 (frame member 300) fixed to the main body frame 10. On the other hand, the movable guide part 220 has two extension parts 222 and 223 extending rearward, and the extension parts 222 and 223 with respect to the housing 63 (frame member 300) and the fixed guide part 210. It can be rotated around a rotation shaft 220A (only one is shown in FIG. 8) provided at the rear of the outer surface in the left-right direction of 223.

  As a result, the movable guide unit 220 is located at the first position where the sheet S can be guided to face the first conveyance guide 100 as shown in FIG. 3 and FIG. 5A, and in FIG. 5B and FIG. The first guide 100 is configured to move (move) relative to the main body frame 10 with respect to the second position where the upstream portion (transport path P) in the transport direction is opened, as shown in FIG. The unit 210 is configured not to move (do not move) with respect to the main body frame 10.

  As shown in FIG. 6, the fixed guide part 210 is provided with a first guide rib 211, and the movable guide part 220 is provided with a second guide rib 221. When the movable guide part 220 is in the first position, the first guide rib 211 protrudes in the transport path P from the second guide rib 221. Thereby, since the paper S can be conveyed in a cross-sectional shape as shown in FIG. 6, it is possible to prevent the left and right ends of the paper S from curling in a cylindrical shape upward.

  The movable guide portion 220 is constantly biased toward the first position by a coil spring 66 as a biasing member as shown in FIG. 7, thereby rotating the top cover 20 from the closed position to the open position. Sometimes it is located at the first position shown in FIG. On the other hand, after the movable guide part 220 is rotated from the first position to the second position shown in FIG. 5B, the movable guide part 220 is held at the second position by the holding part 521 as shown in FIGS. It is configured as follows.

  As shown in FIGS. 7 and 9, the coil spring 66 has its upper end locked to a hook-shaped locking portion 222A formed in the vicinity of the center of the extending portion 222, and is slightly extended in a state where it is slightly extended. Is locked to a hook-like locking portion 510 formed at a position below the locking portion 222A on the front wall of the housing 63 (roof member 500). Thereby, the coil spring 66 urges the movable guide portion 220 toward the first position by the restoring force. Since the locking portion 510 is provided on the left side of the locking portion 222A, more specifically, the coil spring 66 biases the movable guide portion 220 toward the lower left side.

  As shown in FIGS. 8 and 9, the holding portion 521 is a substantially cylindrical convex portion that protrudes toward the right side from the rib 520 of the housing 63 (roof member 500) that faces the left end surface of the extending portion 222. Is formed. On the other hand, on the left end surface of the extending portion 222, a held portion 222B having a substantially arc-shaped side surface protruding outward is formed, and the movable guide portion 220 is rotatable with respect to the housing 63, and It is supported so that it can move slightly in the left-right direction. When the movable guide portion 220 is in the first position shown in FIG. 5A, the end surface of the held portion 222B and the end surface of the holding portion 521 are in contact with each other. When the movable guide portion 220 is in the second position shown in FIG. 5B, the movable guide portion 220 slides slightly to the left due to the urging force of the coil spring 66, and the held portion 222B is moved to the side surface of the holding portion 521 later. By abutting, the rotation of the movable guide part 220 is restricted by the holding part 521. The operation of the movable guide unit 220 will be described later.

  As shown in FIG. 5A, the movable guide unit 220 includes a plurality of grippable plate-like operation units 224 for moving (manipulating) the movable guide unit 220 to the end on the downstream side in the transport direction. Have. Thereby, the user can rotate the movable guide part 220 to the 2nd position shown in FIG.5 (b) by operating the operation part 224. FIG. As shown in FIG. 8A, on the upper surface of the operation portion 224R disposed at the right end portion of the movable guide portion 220, three protrusions 225 that are long on the left and right are provided side by side in the front-rear direction. As a result, the three protrusions 225 serve as marks, and the user can be notified of the movement of the movable guide unit 220 and the presence of the operation unit 224 of the movable guide unit 220.

  Here, the positional relationship between the movable guide portion 220 and the peeling member 64 will be described. As shown in FIG. 4, the four peeling members 64 are all arranged within the width of the movable guide portion 220 in the left-right direction. ing. In other words, all of the four peeling members 64 are provided under the movable guide part 220 in the first position, and none is provided under the fixed guide part 210. Thereby, all the peeling members 64 can be exposed by rotating the movable guide part 220 to the 2nd position.

Next, the configuration of each member constituting the housing 63 of the fixing device 60 will be described.
As shown in FIG. 10A, the casing 63 is formed as a frame member 300 (support portion) that rotatably supports the heating rotator 61 and the pressurizing rotator 62, and as a separate member from the frame member 300. A cover member 400 (cover portion) and a roof member 500 are mainly provided. Although the details will be described later, the cover member 400 and the roof member 500 are configured to be detachable from the frame member 300.

  The roof member 500 is a member that covers the heating rotator 61 and the pressure rotator 62 from above by being assembled to the frame member 300, and is provided with the second conveyance guide 200. The roof member 500 has an engagement piece 531 extending outward in the left-right direction as shown in FIG. 10B on one end side in the left-right direction viewed from the direction of arrow B in FIG. A through hole 532 that is formed and penetrates in the front-rear direction is formed on the other end side.

  Further, as shown in FIG. 3, the roof member 500 includes an inclined wall 540 extending from above the heating rotator 61 toward the rear obliquely upper side opposite to the second conveyance guide 200, and the vicinity of the upper end portion of the inclined wall 540. And a rear wall 550 extending downward. The rear wall 550 extends downward from the upper wall portion 551 extending downward from the vicinity of the upper end portion of the inclined wall 540, the connecting portion 552 extending substantially rearward from the lower end portion of the upper wall portion 551, and the rear end portion of the connecting portion 552. And an upper wall portion 551 and a lower wall portion 553 arranged so as to be displaced forward and backward.

  The rear wall 550 is provided with a plurality of communication ports 555 and 556 (first communication ports) communicating with the inside and the outside of the housing 63 in the left-right direction (see also FIG. 10A). More specifically, the communication port 555 is provided in the upper wall portion 551 near the upper end portion of the inclined wall 540, and the communication port 556 is provided in the lower wall portion 553. Furthermore, the communication ports 555 and 556 are on the upper side of the horizontal plane PL4 passing through the rotation center 62A of the pressurizing rotating body 62 and on the downstream side in the rotation direction of the pressurizing rotating body 62 from the vertical plane PL5 passing through the rotating center 62A. Is provided. On the other hand, in the present embodiment, the top cover 20 has a communication port 25 (second communication port) that communicates the inside and the outside of the top cover 20 at a position facing the connecting portion 552 of the rear wall 550 in the rear end portion of the upper wall. ) Is provided.

  With such a configuration, the heat released from the heating rotator 61, specifically the air heated by the heat, moves rearward and obliquely upward along the lower surface of the inclined wall 540, and from the inside of the housing 63. It is discharged out of the housing 63 through the communication ports 555 and 556, and further discharged out of the top cover 20, that is, out of the laser printer 1 through the communication port 25. Further, since the heat exhaust structure as described above is provided, the laser printer 1 of the present embodiment is not provided with a fan for exhausting the air inside the apparatus to the outside. Thereby, the cost reduction of the laser printer 1 can be achieved.

  A peeling member 64 and a thermistor 65 are attached to the frame member 300, and a portion on the upstream side in the transport direction of the first transport guide 100 including the guide roller 120 is provided. In addition, a pair of guide walls 310 and 320 that are opposed to each other in the front-rear direction are formed in the lower portion of the frame member 300, and the sheet S fed from the process cartridge 50 passes between the pair of guide walls 310 and 320. To do. The surface of each guide wall 310, 320 facing the sheet S is configured to guide the sheet S between the heating rotator 61 and the pressure rotator 62, specifically toward the sheet S. A plurality of pre-fixing guides 311 and 321 are provided side by side in the left-right direction, and are configured as ribs that protrude and extend along the conveyance direction (see also FIG. 11).

  The cover member 400 is a member that covers a part of the frame member 300 by being assembled to the frame member 300, specifically, a part from the upper front side to the lower part of the frame member 300. The upper wall 410 of the cover member 400 is integrated with a first conveyance guide 100 (post-fixing guide) configured to guide the image forming surface S1 of the sheet S after heat fixing toward the outside of the main body frame 10. Is formed. Accordingly, the number of parts can be reduced, and the first conveyance guide 100 can be provided at the same time by assembling the fixing device 60 to the main body frame 10, so that the man-hours for manufacturing the laser printer 1 can be reduced.

  The front wall 420 and the lower wall 430 of the cover member 400 are configured to cover the thermistor 65 by covering the frame member 300. Thus, the thermistor 65 is disposed between the frame member 300 and the cover member 400. By disposing the thermistor 65 in this way, the thermistor 65 can be protected from, for example, an impact when the fixing device 60 is assembled to the main body frame 10 by the cover member 400.

  Further, since the thermistor 65 is covered with the cover member 400, the influence of outside air, air current, etc. on the thermistor 65, which is a non-contact detection type temperature sensor, can be suppressed, so that the temperature of the heating rotator 61 can be detected with high accuracy. Can do. In addition, since the heat released from the heating rotator 61 moves upward by convection, the thermistor 65 is heated by the thermistor 65 disposed obliquely below the heating rotator 61 as in the present embodiment. Since the influence of the heat released from the rotating body 61 can also be suppressed, the temperature can be detected with higher accuracy. In addition, since it is possible to prevent heat from escaping to the outside through the communication ports 25, 555, and 556, the heat around the heating rotator 61 can be suppressed, so that the thermistor 65 has an influence of the heat around the heating rotator 61. The temperature can be suppressed and the temperature can be detected with higher accuracy.

  The lower wall 430 is disposed between the thermistor 65 and the process cartridge 50 so as to separate the heating rotator 61 and the process cartridge 50 (see FIG. 1). Thereby, since the transmission of heat to the process cartridge 50 can be suppressed, the influence of heat on the process cartridge 50 can be suppressed.

  As shown in FIGS. 3 and 11, the cover member 400 is an example of a mounting guide, and the lower surface of the lower wall 430 facing the process cartridge 50 is configured to guide the mounting of the process cartridge 50. Specifically, a plurality of mounting guide ribs 431 configured to protrude downward and extend substantially in the front-rear direction are provided side by side in the left-right direction. As shown in FIG. 2, the guide surface 431 </ b> A of the mounting guide rib 431 is disposed between the fixing device 60 and the process cartridge 50 indicated by a chain line mounted on the main body frame 10 substantially along the mounting direction of the process cartridge 50. It extends so as to face (see straight line L1). More specifically, the mounting guide rib 431 is formed at the center in the conveyance direction of the nip position N2 between the photosensitive drum 51 and the transfer roller 53 where the toner image is transferred in the process cartridge 50, and the heating rotator 61 and the pressure rotator 62. It is inclined toward the side closer to the fixing device 60 with respect to the direction connecting the center of the conveyance direction of the nip position N3 (see the straight line L2). In other words, the mounting guide rib 431 (see the straight line L1) extends so as to form an acute angle with the straight line L2.

  As shown in FIG. 11, the downstream end portions 432 of the mounting guide ribs 431 in the mounting direction of the process cartridge 50 are connected to each other in the left-right direction, and are formed in a shape extending over substantially the entire width in the left-right direction. And as shown in FIG. 3, this downstream side edge part 432 is formed in the curved surface shape in which the cross-sectional shape makes a substantially circular arc shape.

  In the present embodiment, the mounting guide ribs 431 and the plurality of auxiliary ribs 433 (see FIG. 11) formed therebetween extend through the front wall 420 so as to be connected to the guide ribs 111 formed on the upper wall 410. A guide rib 111 and a series of ribs are formed.

  As shown in FIG. 3, the front wall 420 is configured such that when the top cover 20 is closed, a plurality of locations are in contact with the top cover 20 in the left-right direction. Thereby, since inflow of the outside air into the laser printer 1 from between the cover member 400 and the top cover 20 can be suppressed, it is possible to suppress the temperature of the cover member 400 from being changed by the air flowing along the cover member 400. As a result, since the influence of the temperature change in the cover member 400 on the thermistor 65 can be suppressed, the temperature of the heating rotator 61 can be detected with high accuracy.

Here, the assembly of the fixing device 60, mainly the housing 63, will be described.
As shown in FIG. 11, the frame member 300 is formed with support shaft portions 351 (only one is shown) projecting outward on the left and right side walls, and directed downward to the left and right end portions on the front side of the guide wall 310. A locking claw 352 is formed. In addition, the cover member 400 is formed with engagement portions 451 (only one is shown) that can be engaged with the support shaft portion 351 on both the left and right sides of the upper wall 410, and the locking holes 452 are formed on the left and right ends of the lower wall 430. Is formed.

  When assembling the fixing device 60, first, components such as the heating rotator 61 and the thermistor 65 are assembled to the frame member 300. Thereafter, as shown in FIG. 12, the corresponding engaging portion 451 of the cover member 400 is engaged with the support shaft portion 351 of the frame member 300. Then, the downstream end portion 432 side of the cover member 400 is rotated in the direction approaching the guide wall 320 (arrow direction) around the support shaft portion 351, and as shown in FIG. 352 is engaged. As a result, the cover member 400 is assembled to the frame member 300. In this embodiment, since the cover member 400 can be attached to and detached from the frame member 300, the cover member 400 can be assembled to the frame member 300 after the thermistor 65 is assembled to the frame member 300. It is easy to arrange 65 in a state covered with the cover member 400.

  Next, as shown in FIGS. 10A and 10B, the engagement piece 531 of the roof member 500 is engaged while being inserted into the hole 331 formed on one end side in the left-right direction of the frame member 300. The roof member 500 is rotated about the vicinity of the piece 531, and the through hole 532 is engaged with the end portion of the cylindrical fixing portion 332 formed on the other end side of the frame member 300. Thereafter, the roof member 500 is fixed to the frame member 300 by screwing the screw 600 into the hole of the fixing portion 332 through the through hole 532, and the roof member 500 is assembled to the frame member 300, so that the fixing device 60 (housing 63). ) Will be assembled. In this embodiment, since only the other end side of the roof member 500 is fixed to the frame member 300, the roof member 500 can be easily assembled as compared with the configuration in which both sides are fixed.

  As shown in FIG. 8A, the engagement between the engagement piece 531 and the hole 331 is such that a gap is formed between the right end 533 of the roof member 500 and the side wall 333 in which the hole 331 is formed. Has play in the left-right direction. Thereby, even if the roof member 500 is thermally expanded in the left-right direction, the dimensional change at that time can be escaped.

Next, a configuration for detecting the presence or absence of the paper S in the transport path P will be described.
As shown in FIG. 4, the laser printer 1 further includes an actuator 67, an optical sensor 71 as detection means, and a control device 72 as control means.

  The actuator 67 has a contact portion 67A disposed in the transport path P so as to be able to contact the paper S, and a shielding portion 67B provided at an end opposite to the contact portion 67A. The roof member 500 (housing 63) is configured (supported) so as to move, specifically swing, when the paper S comes into contact therewith. As shown in FIG. 3, the portion of the abutment portion 67 </ b> A located in the conveyance path P is disposed on the downstream side in the conveyance direction with respect to the leading end 64 </ b> A where the peeling member 64 acts on the paper S.

  Returning to FIG. 4, the optical sensor 71 includes a light emitting unit 71 </ b> A that emits light and a light receiving unit 71 </ b> B that can receive light emitted from the light emitting unit 71 </ b> A, and the actuator 67 (shielding unit 67 </ b> B) swings. It is configured to detect the presence or absence of the sheet S in the transport path P by detecting a change in the light receiving state of the light receiving unit 71B (for example, a change from an OFF state where light is not received to an ON state where light is received). Has been.

  The control device 72 is a device that controls each part of the laser printer 1, such as a halogen lamp 61H, a motor (not shown) for applying a conveying force to the paper S, and the like, a CPU, a RAM, a ROM, an input / output interface (not shown). And so on. In the present embodiment, the control device 72 drives the motor when the optical sensor 71 detects that the paper S is present in the transport path P for a predetermined time or longer (for example, when the ON state continues for a predetermined time or longer). The conveyance of the paper S is stopped and stopped.

Finally, effects of the laser printer 1 according to this embodiment will be described.
As shown in FIG. 3, at the time of image formation, the sheet S carried out between the heating rotator 61 and the pressurizing rotator 62 has its leading end, and the image forming surface S1 is a guide rib 211 of the second transport guide 200 ( 6), and is conveyed toward the discharge unit 90 while being guided by 221. In the present embodiment, as shown in FIGS. 5A and 5B, the fixed guide portion 210 of the second transport guide 200 is configured not to move, so that it is stiff like cardboard. Even if the paper S is strong, the second transport guide 200 is less likely to rattle, so that the paper S can be transported stably.

  In particular, in the present embodiment, both end portions of the paper S are guided by the stationary guide portion 210 that does not move, so that the conveyance can be made more stable. Further, as shown in FIG. 6, since the first guide rib 211 protrudes from the second guide rib 221, the sheet S is mainly guided by the first guide rib 211 of the fixed guide portion 210. It can be further stabilized. Further, since the movable guide portion 220 is biased toward the first position by the coil spring 66, rattling of the movable guide portion 220 can be suppressed as compared with a configuration in which the movable guide portion 220 is not biased by the coil spring. Can be stably conveyed.

  When a jam occurs in the transport path P, the optical sensor 71 detects that the paper S is present in the transport path P for a predetermined time or more, so that the control device 72 stops driving the discharge roller 90R and the like and the paper S Transport stops. In the present embodiment, the conveyance stop control of the paper S due to the occurrence of a jam is performed without providing a plurality of actuators and optical sensors in the vicinity of the heating rotator 61, so that the cost of the laser printer 1 can be reduced.

  When performing jam processing, as shown in FIG. 2, first, the top cover 20 is rotated to the open position. As a result, as shown in FIG. 14, the portion between the downstream end 201 of the second conveyance guide 200 and the discharge roller 90 </ b> R indicated by the chain line, that is, a part of the conveyance path P can be opened. If the leading edge of the paper is in this vicinity, the paper can be easily taken out without rotating the movable guide portion 220.

  When the top cover 20 is opened, the movable guide portion 220 of the second transport guide 200 provided in the vicinity of the heating rotator 61 is in the first position indicated by the chain line by the biasing force of the coil spring 66. A portion closer to the heating rotator 61 than the two transport guides 200 is covered with a movable guide part 220. Thereby, it is possible to prevent the user from directly touching the heated portion around the heating rotator 61 during the jam processing.

  Further, the cover member 400 provided with the first conveyance guide 100 and the roof member 500 provided with the second conveyance guide 200 are detachable with respect to the frame member 300 supporting the heating rotator 61, that is, the frame member 300. Therefore, the heat transfer from the frame member 300 to the first transport guide 100 or the second transport guide 200 that the user may touch during jam processing can be suppressed. . Further, as described above, the heat released from the heating rotator 61 can be discharged out of the housing 63 through the inclined wall 540 and the communication ports 555 and 556, so that the heat to the first transport guide 100, the second transport guide 200, and the like. Can be further suppressed.

  On the other hand, when the leading edge of the jammed paper (not shown) is between the first conveyance guide 100 and the second conveyance guide 200 in the first position, the jamming process cannot be performed by simply opening the top cover 20, and therefore the operation unit 224 is not operated. To move the movable guide 220 from the first position indicated by the chain line to the second position indicated by the solid line.

  When the movable guide part 220 is rotated from the first position shown in FIGS. 8A and 9A to the second position shown in FIG. 9B, the held part 222 </ b> B faces the rear of the holding part 521. And the contact between the end surface of the held portion 222B and the end surface of the holding portion 521 is released. Then, the movable guide portion 220 slides to the left due to the biasing force of the coil spring 66, so that the held portion 222B moves to the rear side of the holding portion 521 and comes into contact with the side surface of the holding portion 521 from the rear. Thereby, since the rotation of the movable guide part 220 is restricted by the holding part 521, the movable guide part 220 is held at the second position in the opened state.

  When the movable guide part 220 is rotated to the second position, as shown in FIG. 14, substantially the entire conveyance path P can be opened, so that the jammed paper can be exposed and easily taken out.

  In the present embodiment, since the peeling member 64 is disposed within the width of the movable guide portion 220, the movable guide portion 220 is set to the second position even when the paper is jammed in the vicinity of the peeling member 64. By rotating, the peeling member 64 can be exposed, and jamming can be easily performed. Further, the contact portion 67A of the actuator 67 (see FIG. 3) is arranged on the downstream side in the transport direction with respect to the leading end 64A of the peeling member 64, so that when the paper is jammed (when the jam is detected). Since the leading edge of the paper is positioned at least on the downstream side of the leading edge 64A of the peeling member 64, it is possible to easily perform jam processing.

  Furthermore, in this embodiment, since the movable guide portion 220 can be held at the second position by the holding portion 521, it is possible to suppress the movable guide portion 220 from being closed during the jam processing, and this also facilitates Jam processing can be performed.

  When the jam processing is completed, the operation unit 224 is operated to rotate the movable guide unit 220 from the second position to the first position. When a predetermined force or more is applied to the movable guide portion 220 from the second position shown in FIGS. 8 and 9B to the first position shown in FIG. 9A, the held portion 222B is applied to the end surface of the holding portion 521. By the ride, the holding by the holding unit 521 is released. Then, the movable guide part 220 is automatically rotated to the first position by the urging force of the coil spring 66. Thereafter, by rotating the top cover 20 to the closed position, the laser printer 1 becomes ready for image formation. In the present embodiment, since the movable guide unit 220 is automatically moved to the first position by releasing the holding by the holding unit 521, the operability at the time of jam processing can be improved.

  Even when the top cover 20 is rotated from the open position to the closed position without operating the movable guide 220 at the second position, as shown in FIG. Is pressed against the end of the movable guide part 220 and pushed downward, the holding by the holding part 521 is released in the same manner as when operating the operating part 224 when a predetermined force or more is applied, The movable guide part 220 is rotated from the second position to the first position by the biasing force of the coil spring 66. According to this, forgetting to operate the movable guide part 220 can be prevented, and the operability after the jam processing can be improved.

  When a jam occurs between the process cartridge 50 and the fixing device 60, as shown in FIG. 2, in the laser printer 1, the top cover 20 is rotated to the open position to remove the process cartridge 50 from the main body frame 10, and the heating is performed. The sheet S held between the rotating body 61 and the pressure rotating body 62 can be removed from the opening 11. At this time, the sheet S comes into contact with the downstream end 432 of the mounting guide rib 431 and bends at an acute angle at the downstream end 432. In this embodiment, the downstream side that is a contact portion with the sheet S is used. Since the end portion 432 is formed in a cross-sectional curved surface having a width in the left-right direction, the sheet S is pulled out while being guided by the downstream end portion 432, and the breakage of the sheet S is suppressed. it can.

  In the present embodiment, the pre-fixing guides 311 and 321 (see FIG. 3) are provided so that the sheet S fed from the process cartridge 50 is directed between the heating rotator 61 and the pressure rotator 62. Therefore, jamming between the process cartridge 50 and the fixing device 60 can be suppressed.

  If the liquid such as water is accidentally spilled near the first conveyance guide 100 or the second conveyance guide 200 when the top cover 20 is turned to the open position, the laser printer 1 shows a thick arrow in FIG. As shown in FIG. 8, it is possible to prevent the liquid from flowing directly into the heating rotator 61 (inside the fixing device 60) by the second transport guide 200 at the first position indicated by the chain line. Further, even if the liquid on the second conveyance guide 200 flows on the first conveyance guide 100, the liquid is transferred into the fixing device 60 because the guide surface 110 is inclined obliquely downward toward the downstream side in the conveyance direction. Inflow can be suppressed. Furthermore, in this embodiment, since the first conveyance guide 100 is formed integrally with the cover member 400, it is possible to prevent liquid from entering the space in which the thermistor 65 is disposed.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment. About a concrete structure, it can change suitably in the range which does not deviate from the meaning of this invention as follows.

  In the above-described embodiment, the downstream end 432 of the mounting guide rib 431 is continuously formed in a curved shape over substantially the entire width in the left-right direction, but the present invention is not limited to this. For example, the downstream end portion may be formed with a plurality of intermittent curved surfaces having a predetermined width in the left-right direction. Further, the downstream end portion may have a configuration in which a plurality of curved ribs are provided close to each other in the left-right direction (densely). Further, the downstream side end portion may have a roller having a predetermined width in the left-right direction and configured to be driven and rotated by contact with the paper.

  The configuration of the holding unit 521 shown in the embodiment is an example, and the present invention is not limited to the configuration of the embodiment. For example, the holding unit can be moved by moving the movable guide unit from the first position to the second position and then projecting or moving the movable guide unit to a position where the holding unit can come into contact with the movable guide unit. You may be comprised so that a guide part may be hold | maintained in a 2nd position.

  In the above-described embodiment, the configuration in which the fixed guide portions 210 (the first fixed guide portion 210A and the second fixed guide portion 210B) are provided on both the left and right sides of the movable guide portion 220 is exemplified, but the present invention is not limited to this. . For example, the present invention may be configured such that the fixed guide portion is provided only on one side in the width direction of the movable guide portion.

  In the embodiment, the second transport guide 200 is configured such that only the movable guide portion 220 that is a part thereof moves with respect to the main body frame 10 between the first position and the second position. The present invention is not limited to this. For example, the entire second conveyance guide may be configured to move relative to the apparatus main body between the first position and the second position.

  In the embodiment, a plurality of operation units 224 for moving the movable guide unit 220 are arranged. However, the present invention is not limited to this, and for example, the operation unit is only the end of the movable guide unit in the width direction. May be arranged. In the present invention, when the holding portion 521 described above is not provided, the user holds the operation portion with one hand so that the movable guide portion is not closed and holds the movable guide portion in an open state. However, it will be jammed with the other hand, but if the operation part is arranged at the end of the movable guide part in the width direction, it is difficult for both hands to interfere or cross each other. Jam processing can be performed.

  In the above-described embodiment, the coil spring 66 is exemplified as the biasing member that biases the movable guide portion 220 toward the first position. However, the present invention is not limited to this, and for example, a torsion spring, a leaf spring, and the like. Also good. Further, the present invention may be configured not to include an urging member.

  In the embodiment, the discharge roller 90R is configured by the three rollers 91 to 93. However, the present invention is not limited to this, and may be configured by two rollers, for example.

  In the above embodiment, the thermistor 65 is exemplified as the electronic component, but the present invention is not limited to this. For example, the electronic component may be a thermostat that is connected to the halogen lamp 61H and configured to cut off the energization of the halogen lamp 61H when a predetermined temperature or more is detected.

  In the above-described embodiment, the casing 63 of the fixing device 60 is mainly configured to include the frame member 300 (support portion), the cover member 400 (cover portion), and the roof member 500, but the present invention is not limited thereto. Is not to be done. For example, the support part and the cover part may be integrally formed.

  In the embodiment, the laser printer 1 capable of forming only a monochrome image is exemplified as the image forming apparatus, but the present invention is not limited to this. For example, the image forming apparatus may be a printer capable of forming a color image. The image forming apparatus is not limited to a printer, and may be, for example, a copier or a multi-function machine including a document reading apparatus such as a flat bed scanner.

DESCRIPTION OF SYMBOLS 1 Laser printer 10 Main body frame 11 Opening 50 Process cartridge 60 Fixing device 61 Heating rotary body 62 Pressing rotary body 65 Thermistor 100 First conveyance guide 300 Frame member 311 Pre-fixing guide 321 Pre-fixing guide 400 Cover member 432 Downstream end N2 Nip position N3 Nip position S Paper S1 Image forming surface

Claims (6)

An apparatus body having an opening;
A process cartridge that is detachable from the apparatus main body through the opening and is configured to transfer a developer image onto a recording sheet at a transfer nip position ;
A developer image is formed on a recording sheet that has a heating member and a pressure member and is disposed on the process cartridge mounted on the apparatus main body and passes through a fixing nip position between the heating member and the pressure member. A fixing unit configured to be thermally fixed;
A mounting guide configured to extend between the fixing unit and the process cartridge along a mounting direction of the process cartridge and configured to guide the mounting of the process cartridge;
When the recording sheet is jammed in the fixing nip position, the remove the process cartridge is in the recording sheet in a state of being sandwiched between the pressure member and the heating member so as to remove from said opening from said apparatus body An image forming apparatus,
The opening is formed on the upper side of the apparatus body,
The mounting guide is disposed above the process cartridge mounted on the apparatus main body,
The mounting guide extends obliquely downward from the opening toward the bottom of the fixing unit along the mounting direction of the process cartridge, and forms an acute angle with respect to a direction connecting the transfer nip position and the fixing nip position. ,
A recording sheet sandwiched between the heating member and the pressurizing member is opened along the mounting guide at a lower end portion of the mounting guide, which is a downstream end portion of the mounting guide in the mounting direction. An image forming apparatus , wherein a contact portion that comes into contact with a recording sheet when removed from the recording sheet is formed in a curved surface over the entire width in the width direction of the recording sheet. Before the first fixing, the recording sheet extends from the lower end portion of the mounting guide toward the fixing nip position and guides the recording sheet sent out from the process cartridge between the heating member and the pressure member. The image forming apparatus according to claim 1 , further comprising a guide. A recording sheet provided so as to face the first pre-fixing guide and fed from the process cartridge is guided between the heating member and the pressure member between the first pre-fixing guide and the first pre-fixing guide. The image forming apparatus according to claim 2, further comprising a second pre-fixing guide configured to do so. The fixing unit includes a thermistor and a frame member that supports the heating member,
The image forming apparatus according to claim 1, wherein the mounting guide is formed as a separate member from the frame member and is configured to cover the thermistor . The process cartridge has a photoreceptor and a transfer roller,
The image forming apparatus according to claim 1, wherein the transfer nip position is a position between the photoconductor and the transfer roller. 6. The rib according to claim 1, wherein a plurality of ribs extending along a mounting direction of the process cartridge are arranged in a width direction of the recording sheet on a lower surface of the mounting guide. The image forming apparatus described in the item.

Images