JP6724867B2 - Fixing device and image forming device - Google Patents

Description

The present invention relates to a fixing device and an image forming apparatus.

An electrophotographic image forming apparatus includes a fixing device that fixes a toner image transferred onto a medium such as paper.

For example, the fixing device described in Japanese Patent Application Laid-Open Publication No. 2004-242242 discloses a fixing belt, a pressure roller that contacts the fixing belt to form a nip portion, a support member that is in sliding contact with the inner peripheral surface of the fixing belt, and a halogen that heats the support member. It is equipped with a heater. At both ends of the fixing belt in the axial direction, there are provided flange members having a cylindrical portion that is inserted into the inner diameter portion of the axial end of the supporting member.

JP 2012-128074 A

The above-mentioned fixing device adopts a belt fixing method using a fixing belt having a small heat capacity so that the set temperature is reached in a short time. The heat of the fixing belt is absorbed by the paper passing through the nip portion (pressure area). However, outside the paper passing area (both axial end portions) of the fixing belt through which the paper does not pass, the paper may be overheated without being deprived of heat. In order to suppress overheating of both ends of the fixing belt in the axial direction, the both ends of the halogen heater in the axial direction are sometimes covered with a metal cover and fixed to a member inside the fixing belt with screws.

The fixing belt, the cover, the screw, and the like are at approximately the same temperature as room temperature when the fixing device is stopped, but become extremely hot when the fixing device is operating. If the cover and the like repeatedly expand and contract under the influence of a large temperature difference, the screws may loosen and fall off. Then, the cover may also fall off and damage the fixing belt. Even when the pin is pressed into a hole formed in a member in the fixing belt instead of the screw, the same problem as described above may occur.

In order to solve the above problems, the present invention provides a fixing device and an image forming apparatus capable of suppressing the loosening of the fastening member due to the influence of temperature difference.

In order to achieve the above-mentioned object, the fixing device of the present invention forms a pressure area between a fixing member that rotates around an axis to heat toner on a medium and the fixing member that rotates around an axis. The fixing member is provided on the opposite side of the pressing region with the pressing member that presses the toner on the medium passing through the pressing region and the supporting member provided inside the fixing member. A heat source for heating the member from the inside, a temperature rise suppressing member fixed to the axial end portion of the support member via a fastening member, and covering the axial end portion of the heat source, and an axial end portion of the fixing member. A holding member that holds the shape of the axial end portion of the fixing member in a state of being inserted inside and that overlaps with the fastening member and restricts the dropping of the fastening member.

In this case, the fixing member is formed of an endless belt in a cylindrical shape, the holding member is formed in a cylindrical shape, and its outer peripheral surface is brought into contact with the inner peripheral surface of the axial end of the fixing member. A shape-retaining portion that retains a tubular shape, and a guide groove that extends in the axial direction from the inside of the shape-retaining portion and that engages with the fastening member. The fastening groove is formed along the guide groove. It is preferable to include a rail portion that relatively moves the member to guide the shape retaining portion to the inside of the axial end portion of the fixing member.

In this case, the pressurizing area includes a paper passing area through which the medium passes, and a non-paper passing area that is set on an end side in the axial direction with respect to the paper passing area. It is preferable that the heat source is covered at a position corresponding to the non-sheet passing area.

In order to achieve the above-mentioned object, an image forming apparatus of the present invention includes the fixing device described in any one of the above.

According to the present invention, the loosening of the fastening member due to the influence of the temperature difference can be suppressed.

It is a schematic diagram (front view) showing a printer concerning one embodiment of the present invention. FIG. 3 is a cross-sectional view showing a fixing device according to an embodiment of the present invention. FIG. 3 is a perspective view showing the internal structure of the fixing device according to the embodiment of the present invention. FIG. 3 is an exploded perspective view showing the internal structure of the fixing device according to the embodiment of the present invention. FIG. 3 is a perspective view showing a halogen heater, a pressing structure, a temperature rise suppressing member, and the like of the fixing device according to the embodiment of the present invention. FIG. 3 is a perspective view showing a pressing structure, a temperature rise suppressing member, an end holder and the like of the fixing device according to the embodiment of the present invention. FIG. 3 is a perspective view showing a state where the end holder of the fixing device according to the exemplary embodiment of the present invention holds the fixing screw of the temperature rise suppression member.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, "L" shown in each drawing shows "left", "R" shows "right", "U" shows "up", and "D" shows "down".

[Overall printer configuration]
A printer 1 as an example of an image forming apparatus will be described with reference to FIG. FIG. 1 is a schematic view (front view) showing the printer 1. In the following description, the “conveyance direction” refers to the direction in which the sheet S is conveyed. Further, the terms “upstream” and “downstream” and similar terms refer to “upstream” and “downstream” in the transport direction of the sheet S and similar concepts.

The printer 1 includes an apparatus main body 2 having a substantially rectangular parallelepiped appearance. At the lower part of the apparatus main body 2, a paper feed cassette 3 for accommodating a paper sheet S (medium) is provided. A paper discharge tray 4 is provided on the upper surface of the apparatus body 2. The sheet S is not limited to paper and may be resin or the like.

The printer 1 also includes a paper feeding device 5, an image forming device 6, and a fixing device 7. The sheet feeding device 5 is provided at the upstream end of the conveyance path 8 extending from the sheet feeding cassette 3 to the sheet ejection tray 4. The image forming device 6 is provided in an intermediate portion of the transport path 8, and the fixing device 7 is provided downstream of the transport path 8.

The image forming device 6 includes a toner container 10, a drum unit 11, and an optical scanning device 12. The toner container 10 contains, for example, black toner (developer). The drum unit 11 includes a photosensitive drum 13, a charging device 14, a developing device 15, and a transfer roller 16. The transfer roller 16 contacts the photoconductor drum 13 from the lower side to form a transfer nip. The toner may be a two-component developer in which toner and carrier are mixed, or a one-component developer made of magnetic toner.

A control device (not shown) of the printer 1 appropriately controls each device and executes an image forming process as follows. The charging device 14 charges the surface of the photoconductor drum 13. The photoconductor drum 13 receives the scanning light emitted from the optical scanning device 12 and carries an electrostatic latent image. The developing device 15 develops the electrostatic latent image on the photosensitive drum 13 into a toner image using the toner supplied from the toner container 10. The sheet S is sent out from the sheet feeding cassette 3 to the conveyance path 8 by the sheet feeding device 5, and the toner image on the photosensitive drum 13 is transferred to the sheet S passing through the transfer nip. The fixing device 7 fixes the toner image on the sheet S. After that, the sheet S is discharged to the paper discharge tray 4.

[Fixing device]
Next, the fixing device 7 will be described with reference to FIGS. FIG. 2 is a sectional view showing the fixing device 7. FIG. 3 is a perspective view showing the internal structure of the fixing device 7. FIG. 4 is an exploded perspective view showing the internal structure of the fixing device 7.

As shown in FIG. 2, the fixing device 7 includes a housing 20, a fixing belt 21, a pressure roller 22, and a halogen heater 23. The fixing belt 21 and the pressure roller 22 are provided inside the housing 20. The halogen heater 23 is a heat source for emitting light to heat the fixing belt 21. The fixing device 7 adopts a belt fixing method using a fixing belt 21 having a small heat capacity so that the set temperature is reached in a short time.

<Case>
The housing 20 is formed into a substantially rectangular parallelepiped that is long in the front-rear direction. Openings for inserting the sheet S are formed on both left and right sides of the housing 20. An entrance guide 26 for guiding the sheet S to the contact portion (pressure area N) between the fixing belt 21 and the pressure roller 22 is provided at the opening on the right side of the housing 20. A conveyance roller pair 27 for sending the sheet S to the downstream side is provided at the left side opening of the housing 20.

<Fixing belt>
As shown in FIGS. 2 to 4, a fixing belt 21 as an example of a fixing member is an endless belt and is formed in a substantially cylindrical shape that is long in the front-rear direction. The fixing belt 21 is made of, for example, a heat-resistant and elastic synthetic resin material such as polyimide resin. Both front and rear ends of the fixing belt 21 are supported by the housing 20 via a pair of end holders 60 (holding members) (see FIG. 3 ). As will be described in detail later, as shown in FIG. 3, each end holder 60 is rotatably supported by the fulcrum shaft 67. An arm portion 61A extending rightward is formed on the right side of each end holder 60. Each arm portion 61A is formed in a substantially U-shape with its upper side opened as seen from the side surface.

(Pressing structure)
As shown in FIG. 2, a pressing structure 24 is provided inside (inside) the fixing belt 21. The pressing structure 24 includes a supporting member 30, a reflecting member 31, and a pressing member 32.

As shown in FIGS. 2 and 4, the support member 30 is formed of, for example, a metal material in a substantially rectangular tubular shape that is long in the front-rear direction. The support member 30 penetrates the fixing belt 21 in the axial direction. Both front and rear end portions of the support member 30 have a bottom plate 30A and a pair of side plates 30B extending upward from the left and right end portions thereof, and are formed in a substantially U shape with the upper portion open. A positioning recess 35 is formed in the bottom plate 30A so as to be recessed inward from the axially outer end. A screw hole 36 in which a female screw is formed is opened in the pair of side plates 30B. On the outer surface of the right side plate 30B, a pair of substantially cylindrical positioning bosses 37 are formed at positions sandwiching the screw holes 36. A substantially cylindrical positioning boss (not shown) is formed on the outer surface of the left side plate 30B axially outside the screw hole 36. The reflecting member 31 is formed of, for example, a metal material in a substantially plate shape that is long in the front-back direction. The reflection member 31 is fixed to the upper surface of the support member 30 and has a function of reflecting the light of the halogen heater 23.

As shown in FIG. 2, the pressing member 32 includes a base member 33 fixed to the lower surface of the support member 30 and a sliding sheet 34 wound around the base member 33. The pressing member 32 has a function of receiving the fixing belt 21 pressed against the pressure roller 22. The base member 33 is formed of a heat-resistant synthetic resin or the like into a substantially plate shape that is long in the front-rear direction. The sliding sheet 34 is, for example, a woven fabric woven using PTFE (Polytetrafluoroethylene) fibers or the like. The sliding sheet 34 has a function of coming into contact with the inner peripheral surface of the fixing belt 21 facing the pressure area N and reducing friction with the fixing belt 21.

<Pressure roller>
As shown in FIGS. 2 to 4, a pressure roller 22 as an example of a pressure member is formed in a substantially cylindrical shape that is long in the front-rear direction. The pressure roller 22 includes a metal cored bar 22A and an elastic layer 22B such as a silicone sponge laminated on the outer peripheral surface thereof. Both front and rear ends of the pressure roller 22 (core metal 22A) are supported by the housing 20 so as to rotate about an axis. A drive motor (not shown) is connected to the cored bar 22A via a gear train or the like, and the pressure roller 22 is rotationally driven by the drive motor.

<Halogen heater>
As shown in FIGS. 2 and 4, the halogen heater 23, which is an example of a heat source, is formed in a substantially rod shape (substantially columnar shape) that is long in the front-rear direction. The halogen heater 23 is arranged inside the fixing belt 21 and penetrates the fixing belt 21 in the axial direction (front-back direction). The halogen heater 23 is provided on the opposite side of the pressure area N with the support member 30 provided inside the fixing belt 21 interposed therebetween.

As shown in FIG. 4, the halogen heater 23 includes a substantially columnar light emitting portion 23A containing a filament, and a pair of electrode portions 23B fixed to both axial end portions thereof. The pair of electrode portions 23B are supported by the pair of end holders 60 while penetrating the pair of end holders 60 (see FIG. 3). The halogen heater 23 heats the fixing belt 21 from the inside by using the light in the infrared region emitted from the light emitting section 23A. Specifically, the light emitted from the light emitting unit 23A is directly or reflected by the reflecting member 31 and is applied to the upper inner surface of the fixing belt 21. As a result, the upper side of the fixing belt 21 is heated. Although the halogen heater 23 is used as the heat source in the above description, a heat source such as a carbon heater may be used instead of the halogen heater 23.

(Pressure mechanism)
As shown in FIG. 3, the housing 20 is provided with a pressure mechanism 40 that adjusts the force (pressure) for pressing the fixing belt 21 against the pressure roller 22. The pressurization mechanism 40 includes a pair of eccentric cams 41, a pair of actuation metal plates 42, and a pair of coil springs 43.

The pair of eccentric cams 41 are so-called disc cams and are fixed to both ends of a cam connecting shaft 44 extending in the front-rear direction. The cam connecting shaft 44 is adjacent to the right side of the pressure roller 22 and is provided substantially parallel to the pressure roller 22. A cam motor 46 is connected to one end (front end) of the cam connecting shaft 44 via a gear train 45. Each of the operating metal plates 42 is formed in a substantially U shape with an open bottom, and is arranged below the arm portion 61A of the end holder 60. An operating roller 47 that is in contact with the outer peripheral surface of the eccentric cam 41 is supported below each operating sheet metal 42. An operating rod 48 penetrating an axial hole opened in the arm portion 61A is fixed to the upper portion of each operating sheet metal 42. Each coil spring 43 is installed between the upper end portion of the operating rod 48 and the arm portion 61A, and urges the arm portion 61A downward.

When each eccentric cam 41 rotates about the cam connecting shaft 44 by the drive of the cam motor 46, each operating metal plate 42 (operating rod 48) reciprocates in the vertical direction. For example, when each eccentric cam 41 pushes the operation roller 47 downward and each operation sheet metal 42 descends, the coil spring 43 is compressed and the biasing force increases. Then, the end holders 60 rotate downward about the fulcrum shaft 67, so that the fixing belt 21 is pressed against the pressure roller 22 (pressurized state). In other words, the pressure roller 22 is relatively pressed against the lower surface of the fixing belt 21 and forms a pressure area N between itself and the fixing belt 21. On the other hand, when each eccentric cam 41 releases the pressing of the operating roller 47 and each operating metal plate 42 rises, the coil spring 43 extends and the urging force decreases. Then, each end holder 60 pivots slightly upward about the fulcrum shaft 67, and the pressure in the pressurizing region N decreases (depressurized state). The pressurizing region N refers to a region from a position on the upstream side where the pressure is 0 Pa to a position on the downstream side where the pressure becomes 0 Pa again via a position where the pressure is maximum. A pressure mechanism (not shown) may be configured so that the pressure roller 22 is pressed against the fixing belt 21.

A temperature sensor (not shown) such as a thermopile or a thermistor that detects the temperature of the surface of the fixing belt 21 is provided inside the housing 20. A halogen heater 23, a drive motor, a cam motor 46, a temperature sensor, and the like are electrically connected to the control device of the printer 1. The control device controls the halogen heater 23 and the like via various drive circuits. Further, the rotation of the fixing belt 21 or the like that conveys the sheet S to the downstream side is referred to as “forward rotation” (see the solid arrow in FIG. 2).

[Function of fixing device]
Here, the operation (fixing process) of the fixing device 7 will be described. When the fixing process is performed, the pressure area N is in a pressure state.

First, the control device drives and controls the drive motor and the halogen heater 23. The pressure roller 22 is rotated by receiving the driving force of the drive motor, and the fixing belt 21 is driven by the pressure roller 22 to rotate forward (see the solid arrow in FIG. 2). The halogen heater 23 heats the fixing belt 21 from the inside. The temperature sensor detects the temperature of the fixing belt 21 and sends a detection signal to the control device via the input circuit. When the control device receives a detection signal indicating that the temperature has reached the set temperature (for example, 150 to 200° C.) from the temperature sensor, the control device starts execution of the image forming process described above. The sheet S onto which the toner image has been transferred enters into the housing 20, and the fixing belt 21 heats the toner (toner image) on the sheet S passing through the pressure area N while rotating forward about the axis. The pressure roller 22 presses the toner on the sheet S passing through the pressure region N while rotating around the axis. Then, the toner image is fixed on the sheet S. Then, the sheet S on which the toner image is fixed is sent out of the housing 20 and discharged to the paper discharge tray 4.

Note that, when the printer 1 (fixing device 7) is stopped, or when a conveyance failure (jam) of the sheet S occurs in the housing 20 (pressurizing region N) of the fixing device 7, the control device controls the cam motor 46. Drive control is performed to bring the pressurizing region N into a depressurized state. When a jam occurs, the user opens an opening/closing door (not shown) provided on the left side surface of the apparatus main body 2 to remove the jammed sheet S (execute jam processing). At this time, when the user pulls the sheet S upstream in the conveying direction (passing direction), the fixing belt 21 or the like may be dragged by the sheet S and rotate in the reverse direction (rotation in the direction opposite to the normal rotation) (FIG. 2). See the dashed arrow.

By the way, the sheet S passes near the center of the pressure region N (such as the fixing belt 21) in the front-rear direction, and does not pass through both ends of the pressure region N in the front-rear direction. That is, the pressure area N is set in the vicinity of the center in the front-rear direction through which the sheet S passes, and the non-passage area set in the axial direction (front-rear direction) at both end sides of the paper passage area N1. The paper area N2 is included (see FIG. 4). The heat of the fixing belt 21 is taken by the sheet S passing through the sheet passing area N1. However, the both ends of the fixing belt 21 in the axial direction (the non-sheet passing area N2) through which the sheet S does not pass may be excessively heated without being absorbed by the sheet S. Therefore, this fixing device 7 is provided with a pair of temperature rise suppressing members 50 that cover both axial end portions of the halogen heater 23 (light emitting portion 23A) in order to suppress overheating of both axial end portions of the fixing belt 21. There is.

(Temperature rise suppressing member)
The temperature rise suppression member 50 will be described with reference to FIGS. 5 and 6. FIG. 5 is a perspective view showing the halogen heater 23, the pressing structure 24, the temperature rise suppressing member 50, and the like. FIG. 6 is a perspective view showing the pressing structure 24, the temperature rise suppression member 50, the end holder 60, and the like. Since the pair of temperature rise suppression members 50 are symmetrical in the front-rear direction, the front temperature rise suppression member 50 will be described below.

The temperature rise suppressing member 50 is formed of, for example, a metal material such as iron or aluminum alloy in a substantially semi-cylindrical shape extending in the front-rear direction. The temperature rise suppression member 50 includes a curved portion 51 and a pair of leg portions 52.

The curved portion 51 is a portion for covering the axial end portion of the halogen heater 23 (light emitting portion 23A). The curved portion 51 is curved in a convex shape upward as viewed from the front. The curved portion 51 is formed with a plurality of light passing holes 53 each having a substantially rectangular shape elongated in the front-rear direction. The plurality of light passage holes 53 are arranged on the inner side (center side) of the curved portion 51 in the axial direction at substantially equal intervals in the left-right direction.

The pair of legs 52 are formed to extend downward and axially outward from both left and right ends of the bending portion 51. A circular screw through hole 54 is formed in each of the pair of legs 52. A pair of positioning holes 55 are formed in the right leg portion 52 at positions sandwiching the screw through hole 54. The front right positioning hole 55 is formed in a substantially elliptical shape that is long in the front-rear direction, and the rear right positioning hole 55 is formed in a circular shape. In addition, a circular positioning hole 55 is formed in the left leg portion 52 axially outside the screw through hole 54.

(Installation work of temperature rise suppression member)
A procedure (attachment work) for attaching the temperature rise suppression member 50 to the support member 30 will be described.

The temperature rise suppressing member 50 covers the axial end portion of the light emitting portion 23A arranged above the supporting member 30 (see FIG. 5). At this time, the worker fits the positioning holes 55 of the pair of legs 52 into the positioning bosses 37 of the support member 30 (see FIG. 6 ). Then, the temperature rise suppression member 50 is temporarily held by the support member 30 in a posture of straddling the axial end portion of the light emitting portion 23A.

Next, the worker inserts a fixing screw B1 as an example of a fastening member through each screw through hole 54 of the pair of legs 52 and engages with each screw hole 36 of the support member 30. As described above, the temperature rise suppression member 50 is fixed to the axial end portion of the support member 30 via the fixing screw B1 and covers the halogen heater 23 (light emitting portion 23A) at the position corresponding to the non-sheet passing area N2. become. It should be noted that a part of the light emitted from the axial end portion of the light emitting portion 23A is irradiated to the upper inner surface of the fixing belt 21 through each of the light passage holes 53 of the temperature rise suppressing member 50. That is, the temperature rise suppression member 50 does not block all the light emitted from the axial end portion of the light emitting portion 23A.

By the way, the support member 30, the temperature rise suppression member 50, the fixing screw B1 and the like are at substantially the same temperature as room temperature when the fixing device 7 is stopped, but are extremely high temperature (about 200 to 350° C.) when the fixing device 7 is operating. )become. When the support member 30, the temperature rise suppression member 50, and the like repeatedly expand and contract under the influence of a large temperature difference, the fixing screw B1 may loosen and fall off. Then, the temperature rise suppression member 50 may also fall off, damaging the fixing belt 21. Therefore, the fixing device 7 includes a pair of end holders 60 for preventing the fixing screw B1 from falling off.

(End holder)
Next, with reference to FIGS. 3, 6 and 7, a pair of end holders 60 provided at both ends of the fixing belt 21 in the axial direction will be described. FIG. 7 is a perspective view showing a state in which the end holder 60 holds the fixing screw B1 of the temperature rise suppressing member 50. The pair of end holders 60 are symmetrical in the front-rear direction, and therefore the front end holder 60 will be described below.

As shown in FIG. 6, the end holder 60 includes a holder sheet metal 61, a shape retaining portion 62, and a pair of rail portions 63. The holder sheet metal 61 is fixed to the housing 20. The shape retaining portion 62 and the pair of rail portions 63 are supported by the holder sheet metal 61.

The holder sheet metal 61 is formed in a substantially plate shape from a metal material such as iron or aluminum alloy. A support hole 64 through which the axial end of the support member 30 and the electrode portion 23B of the halogen heater 23 penetrate is opened in the central portion of the holder sheet metal 61 (see FIG. 3). The holder sheet metal 61 is provided with a positioning projection 65 that fits into the positioning recess 35 (see FIG. 4) of the support member 30 with the support member 30 penetrating the support hole 64 (see FIG. 3). .. A first connecting piece 66 is formed at an upper end portion of the holder sheet metal 61 so as to extend inward in the axial direction, and a screw hole 66A in which the connecting screw B2 is meshed is formed in the first connecting piece 66.

A fulcrum shaft 67 is fitted to the lower left part of the holder sheet metal 61 (see FIG. 3), and an arm portion 61A is formed on the right side of the holder sheet metal 61. A second connecting piece 68 is formed in an axially inner upper portion of the arm portion 61A so as to extend inward in the axial direction, and a through hole 68A through which the connecting screw B2 passes is opened in the second connecting piece 68.

As shown in FIG. 6, the shape retaining portion 62 is formed of, for example, a heat-resistant synthetic resin material into a substantially cylindrical shape. More specifically, the shape retaining portion 62 is formed in a substantially cylindrical shape whose axial lower surface is substantially flat and whose lower surface is substantially flat. The shape retaining portion 62 is fixed to the inside of the holder sheet metal 61 in the axial direction so as to surround the support hole 64. The shape retaining portion 62 has a function of retaining the tubular shape by contacting the outer peripheral surface of the shape retaining portion 62 with the inner peripheral surface of the axial end portion of the fixing belt 21 in a state of being inserted inside the fixing belt 21. An annular sliding film F that reduces friction with the end surface of the fixing belt 21 is fitted in the shape holding portion 62.

Each of the pair of rail portions 63 is formed in a substantially plate shape, for example, from a synthetic resin material having heat resistance. The pair of rail portions 63 are formed to extend from the inside of the shape retaining portion 62 along the axial direction. Specifically, the pair of rail portions 63 are arranged inside the shape holding portion 62 at positions sandwiching the support hole 64 from the left and right directions, and extend toward the inside in the axial direction of the shape holding portion 62. The radial outer surface of each rail portion 63 is curved along the shape of the shape retaining portion 62, and the radial inner surface of each rail portion 63 is formed substantially vertically.

A guide groove 63A is formed on the radially inner surface of each rail portion 63 so as to be recessed radially outward. Each guide groove 63A extends axially outward from the tip of the rail 63. Both upper and lower edges of the tip of each guide groove 63A are chamfered obliquely. The guide grooves 63A are engaged with each other in a state where the fixed screw B1 relatively moves. The guide groove 63A on the right side has a guide recess 63B that is cut away from the tip toward the outside in the axial direction.

(Installation of the end holder)
A procedure (mounting work) for closing the axial end surface opening of the fixing belt 21 by the end holder 60 will be described.

The end holder 60 is arranged such that each rail 63 is directed toward the axial end surface opening of the fixing belt 21 (see FIG. 6 ). The worker inserts each rail portion 63 of the end holder 60 inside the axial end of the fixing belt 21. Further, the worker inserts the head H of each fixing screw B1 to which the temperature rise suppressing member 50 is fixed into the guide groove 63A of each rail 63. At this time, since the upper and lower edges of each guide groove 63A are chamfered, each fixing screw B1 (head H) can be smoothly inserted into the guide groove 63A.

Each rail portion 63 enters the inside of the fixing belt 21 while being guided by the fixing screw B1 (head H) fitted in each guide groove 63A, and eventually the shape holding portion 62 enters the inside of the fixing belt 21. Begin to. The shape retaining portion 62 also enters the inside of the fixing belt 21 while being guided by the fixing screw B1 fitted in each guide groove 63A. In this way, each rail portion 63 has a function of relatively moving the fixing screw B1 along the guide groove 63A to guide the shape holding portion 62 to the inside of the axial end portion of the fixing belt 21.

When the end portion of the fixing belt 21 abuts the holder sheet metal 61 with the sliding film F sandwiched therebetween, the insertion of the end portion holder 60 into the fixing belt 21 is completed (see FIG. 7). In this state, the heads H of the pair of fixing screws B1 are fitted in the guide grooves 63A of the rail portion 63, respectively, and are covered by the rail portion 63. The head H of the right fixing screw B1 is slightly exposed from the guide recess 63B of the rail 63, but most of it is covered by the rail 63 (see FIG. 7). Further, the shape holding portion 62 holds the substantially cylindrical shape of the fixing belt 21 by bringing its outer peripheral surface into contact with the inner peripheral surface of the axial end portion of the fixing belt 21. Further, the electrode portion 23B of the halogen heater 23 and the axial end portion of the support member 30 penetrate through the support hole 64 of the holder sheet metal 61 (see FIG. 3). Further, the positioning concave portion 35 (see FIG. 5) of the support member 30 is fitted into the positioning convex portion 65 of the holder sheet metal 61 (see FIG. 3).

Next, as shown in FIG. 3, the worker inserts the connecting screw B2 from the upper surface of the housing 20 and engages with the screw hole 66A of the first connecting piece 66. Further, the operator inserts the connecting screw B2 into the through hole 68A of the second connecting piece 68 and engages with the screw hole (not shown) of the housing 20. As described above, the end holder 60 is fixed to the housing 20. That is, the fixing belt 21 and the supporting member 30 (pressing structure 24) are supported by the housing 20 via the end holder 60.

In the fixing device 7 according to the first embodiment described above, the end holder 60 holds the shape of the axial end portion of the fixing belt 21 in a state of being inserted inside the axial end portion of the fixing belt 21. In addition, the fixing screw B1 overlaps with the fixing screw B1 to prevent the fixing screw B1 from falling off.
According to this configuration, even if the fixing screw B1 is loosened due to the large temperature difference caused by turning on/off the fixing device 7, the fixing screw B1 is pressed by the end holder 60 (rail portion 63). It is possible to prevent the temperature rise suppressing member 50 fixed via the fixing screw B1 from falling off.

Further, in the fixing device 7 according to the first embodiment, the rail portion 63 is configured to extend in the axial direction from the shape holding portion 62 and enter the inside of the fixing belt 21 before the shape holding portion 62. Further, the guide groove 63A of the rail portion 63 is engaged with the fixing screw B1 (head portion H), and in this state, the shape holding portion 62 enters the inside of the fixing belt 21. According to this configuration, the shape retaining portion 62 can be smoothly inserted inside the fixing belt 21 using the fixed screw B1 that relatively moves along the guide groove 63A as a guide. As a result, it is possible to suppress a problem such as the shape retaining portion 62 hitting the end portion of the fixing belt 21 and damaging it.

Further, according to the fixing device 7 according to the present embodiment, since the temperature rise suppressing member 50 covers the halogen heater 23 at a position corresponding to the non-paper passing area N2, the non-paper passing area N2 of the fixing belt 21 is overheated. Heating can be suppressed.

In the fixing device 7 according to the present embodiment, the end holder 60 has the pair of rail portions 63, but the present invention is not limited to this, and the number of rail portions 63 may be one. Further, although the temperature rise suppression member 50 is fixed to the support member 30 by the pair of fixed screws B1, the temperature rise suppression member 50 may be fixed to the support member 30 by one fixed screw B1 or two. It may be fixed to the support member 30 with the above fixing screws B1. Further, the pair of side plates 30B of the support member 30 are formed with the positioning bosses 37 of different numbers, but the present invention is not limited to this. The same number of positioning bosses 37 may be provided on the pair of side plates 30B, or the positioning bosses 37 may be omitted. The positioning holes 55 formed in the pair of leg portions 52 of the temperature rise suppression member 50 may be formed according to the number and position of the positioning bosses 37, and may be omitted if unnecessary.

Further, although the fixing screw B1 is used as an example of the fastening member in the fixing device 7 according to the present embodiment, a nut may be used instead of the fixing screw B1. That is, the fastening member may include a male screw that meshes with (fits into) the female screw, and may be fastened by a screw action. Moreover, a pin (with a head) as another example of the fastening member may be press-fitted into a hole opened in the support member 30 (side plate 30B) (not shown).

Further, in the description of the present embodiment, the case where the present invention is applied to the monochrome printer 1 is shown as an example, but the present invention is not limited to this, and the present invention may be applied to, for example, a color printer, a copying machine, a facsimile, or a multi-function peripheral. You may apply.

It should be noted that the above description of the embodiment shows one aspect of the fixing device and the image forming apparatus according to the present invention, and the technical scope of the present invention is not limited to the above embodiment.

1 Printer (image forming device)
7 Fixing device 21 Fixing belt (fixing member)
22 Pressure roller (pressure member)
23 Halogen heater (heat source)
30 Support Member 50 Temperature Rise Control Member 60 End Holder (Holding Member)
62 shape retaining part 63 rail part 63A guide groove B1 fixing screw (fastening member)
N Pressurized area N1 Paper passing area N2 Non-paper passing area S Sheet (medium)

Claims (4)

A fixing member that heats the toner on the medium while rotating around the axis,
A pressing member that forms a pressing region between the fixing member and the fixing member while rotating around an axis, and presses the toner on the medium passing through the pressing region;
A heat source which is provided on the opposite side of the pressure region with a support member provided inside the fixing member, and heats the fixing member from the inside;
A temperature rise suppressing member fixed to the axial end of the support member via a fastening member and covering the axial end of the heat source;
A holding member that retains the shape of the axial end portion of the fixing member in a state of being inserted inside the axial end portion of the fixing member and that overlaps with the fastening member and restricts the falling of the fastening member. A fixing device comprising: The fixing member is formed of an endless belt in a tubular shape.
The holding member is
A shape-retaining portion that is formed in a tubular shape and that holds the tubular shape by bringing the outer peripheral surface into contact with the inner peripheral surface of the axial end portion of the fixing member;
The shape-retaining portion is formed so as to extend in the axial direction from the inside of the shape-retaining portion, has a guide groove with which the fastening member engages, and relatively moves the fastening member along the guide groove. The fixing device according to claim 1, further comprising: a rail portion that guides the inside of an axial end portion of the fixing member. The pressurizing area includes a paper passing area through which the medium passes, and a non-paper passing area that is set closer to the end in the axial direction than the paper passing area,
The fixing device according to claim 1, wherein the temperature increase suppressing member covers the heat source at a position corresponding to the non-sheet passing area. An image forming apparatus comprising the fixing device according to claim 1.

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