JP4575716B2 - Fixing device - Google Patents

Description

The present invention relates to a fixing device that is mounted on an image forming apparatus such as an electrostatic copying machine, a printer, or a facsimile machine and melts and fixes unfixed toner on a sheet to the sheet.

A fixing device configured to heat the fixing roller not from the inside but from the outside is already known. One typical example of this type of fixing device includes a fixing roller, a pressure roller that is pressed against the fixing roller, and a plurality of heat rollers that are in pressure contact with the fixing roller and incorporate heating means (Patent Document 1). reference). The fixing roller is composed of a mandrel made of an iron hollow tube and silicon rubber covering the periphery of the mandrel. Each of the heat rollers is constituted by an aluminum hollow tube whose surface is coated with a fluororesin.

Since the fixing device directly heats the surface of the fixing roller, the temperature raising time of the fixing roller can be shortened, and therefore the warm-up time can be shortened. However, since the supply of heat to the fixing roller by the plurality of heat rollers is limited to a slight nip width between each of the heat rollers and the fixing roller, the amount of heat supply is limited. As a result, when it is desired to further shorten the heating time of the fixing roller, it is necessary to widen the nip width. However, when the nip width is widened, a local load on the fixing roller increases, so that fixing is performed. The driving torque of the roller increases, and it becomes necessary to strengthen the driving system. In addition, there is a possibility that the silicon rubber of the fixing roller is damaged early and the durability is impaired.

A fixing device that can solve the above problem has already been filed by Kyocera Mita Corporation, which is the present applicant (for example, Japanese Patent Application No. 2003-400247). A typical example of this fixing device is a fixing roller, a pressure roller pressed against the fixing roller, a plurality of belt support rollers arranged at intervals, and an endless belt wound around each of the belt support rollers. And a belt. A part of the outer peripheral surface of the endless belt is brought into pressure contact with a part of the outer peripheral surface of the fixing roller, and at least one belt support roller is constituted by a heat roller in which a heating unit is incorporated. The fixing device is configured such that a part of the outer peripheral surface of the endless belt is pressed against a part of the outer peripheral surface of the fixing roller. That is, a flexible endless belt is pressed against a part of the outer peripheral surface of the fixing roller to form a nip region, so that the nip width for heating the fixing roller is greatly increased as compared with the conventional case. Can do. As a result, it is possible to shorten the warm-up time by shortening the heating time of the fixing roller without increasing the local load on the fixing roller and without impairing the durability of the fixing roller.

However, it has been found that the fixing device further has the following technical problems to be solved. That is, in the fixing device, the heat roller is held in a state of being constantly pressed (pressed) against the fixing roller via the endless belt, and the heat roller is separated from the fixing roller and not always pressed (separated). There is an embodiment held in the state).

In the embodiment in which the heat roller is constantly pressed against the fixing roller via the endless belt, the elastic member of the fixing roller (generally silicon rubber) while the fixing roller and the endless belt are driven to rotate. ) Is repeatedly deformed in a state where heat is applied to the pressing portion, so that permanent deformation (permanent distortion) is likely to occur, and the life may be shortened.

On the other hand, in the case of an embodiment in which the heat roller is kept away from the fixing roller and is not constantly pressed, even if the temperature control of the heat roller is performed while the rotational driving of the fixing roller and the endless belt is stopped, Since the heat of the heat roller is transmitted only to the fixing roller via the endless belt, the surface temperature of the fixing roller is decreased relatively quickly. As a result, it takes a relatively long time to rotationally drive the fixing roller and the endless belt again to raise the surface temperature of the fixing roller to a fixable temperature.

Further, when performing jam processing, toner may adhere to the surface of the endless belt. When toner adheres to the surface of the endless belt, it is necessary to clean it. To clean the surface of the endless belt, the toner adhered to the surface of the endless belt by bringing a cleaning member into contact with the surface of the endless belt. It is conceivable to move the toner to the cleaning member and collect the toner moved to the cleaning member. However, such a cleaning means has a large number of parts and a complicated structure.
JP 11-84934 A

An object of the present invention is to ensure the life of a fixing roller as required by preventing permanent deformation (permanent distortion) of the fixing roller, and to raise the surface temperature of the fixing roller to a fixable temperature in a relatively short time. It is an object of the present invention to provide a novel fixing device that makes it possible.

Another object of the present invention is to ensure the lifetime of the fixing roller as required by preventing permanent deformation (permanent distortion) of the fixing roller, and to raise the surface temperature of the fixing roller to a fixable temperature in a relatively short time. In addition, by enabling the cleaning of the endless belt without specially providing a cleaning member, it is possible to guarantee good image fixing and prevent paper smearing. It is to provide a fixing device.

According to one aspect of the present invention , in a fixing device including a fixing roller and a pressure roller pressed against the fixing roller, each of a plurality of belt support rollers disposed at a distance from each other, and each of the belt support rollers An endless belt wound around and having a partial area of the outer peripheral surface pressed against a partial area of the outer peripheral surface of the fixing roller; and a heating unit that heats at least one belt support roller to form a heat roller; A displacement capable of displacing at least one heat roller into a pressing position for pressing the fixing roller via the endless belt and a non-pressing position spaced from the fixing roller and not pressing the fixing roller via the endless belt. mechanism and, it is found provided and a controller for controlling the device, the controller, at least one of the heat roller, the rotation of the fixing roller and the endless belt is stopped There is provided a fixing device characterized in that the fixing device is positioned at a pressing position while the fixing roller and the endless belt are rotationally driven and positioned at a non-pressing position .
According to another aspect of the present invention, in a fixing device including a fixing roller and a pressure roller pressed against the fixing roller, a plurality of belt support rollers arranged at intervals from each other; An endless belt that is wound between each of the belts and a partial region of the outer peripheral surface is pressed against a partial region of the outer peripheral surface of the fixing roller, and a heating unit that heats at least one belt support roller to form a heat roller And at least one heat roller can be displaced between a pressing position for pressing the fixing roller via the endless belt and a non-pressing position spaced from the fixing roller and not pressing the fixing roller via the endless belt. a displacement mechanism, provided with a controller for controlling the device, controller is at least one of the heat roller, while the printing operation is performed positioned in the non-pressing position, There is provided a fixing device characterized in that it is positioned at a pressing position during other states except during the printing operation .
The controller holds the surface temperature of at least one heat roller at a predetermined value or more in a state where at least one heat roller is positioned at the pressing position and rotation of the fixing roller and the endless belt is stopped. It is preferable that the fixing roller and the endless belt are rotationally driven every predetermined time for a predetermined time.
According to still another aspect of the present invention, in a fixing device including a fixing roller and a pressure roller pressed against the fixing roller, a plurality of belt support rollers disposed at a distance from each other, and a belt support roller An endless belt that is wound between each of the belts and a partial region of the outer peripheral surface is pressed against a partial region of the outer peripheral surface of the fixing roller, and at least one belt support roller is heated to form a heat roller And at least one heat roller may be displaced to a pressing position that presses the fixing roller via the endless belt and a non-pressing position that is spaced from the fixing roller and does not press the fixing roller via the endless belt. A displacement mechanism capable of displacing at least one heat roller to a plurality of non-pressing positions at different distances from the fixing roller, The nip width of the nip region formed by pressing a partial region of the outer peripheral surface of the endless belt against a partial region of the outer peripheral surface of the fixing roller is a distance that at least one heat roller is separated from the fixing roller. There is provided a fixing device that is smaller as it is positioned at a larger non-pressing position .
A controller for controlling the apparatus is provided, and the controller positions at least one heat roller at a non-pressing position where the distance from the fixing roller is larger than the non-pressing position during a normal printing operation, and sets the nip width. It is preferable to execute the printing operation in a state set smaller than that in the normal printing operation.
A controller for controlling the apparatus is provided, and a cleaning mode is provided in which a sheet can pass through the fixing device during a non-printing operation. The controller fixes at least one heat roller more than a non-pressing position during a normal printing operation. It is preferable that the cleaning mode is executed in a state where the distance away from the roller is set to a non-pressing position where the distance is large and the nip width is set smaller than that in the normal printing operation.
The displacement mechanism includes a bearing member that is movably supported on each of a pair of side walls that are arranged to face each other with a space therebetween, and that both ends of the heat roller are rotatably supported, and each of the bearing members It is preferable that the heat roller includes a driving unit that can displace the heat roller in a direction approaching and separating from the outer peripheral surface of the fixing roller.
The displacement mechanism includes spring means for constantly urging each of the bearing members in a direction in which the heat roller is separated from the outer peripheral surface of the fixing roller, and the drive means is moved by the urging means in the separated direction. It is preferable to include a cam member disposed in contact with each of the bearing members so as to block, and a rotating means disposed corresponding to each of the cam members and rotating each of the cam members. .
According to still another aspect of the present invention, in a fixing device including a fixing roller and a pressure roller pressed against the fixing roller, a plurality of belt support rollers disposed at a distance from each other, and a belt support roller An endless belt that is wound between each of the belts and a partial region of the outer peripheral surface is pressed against a partial region of the outer peripheral surface of the fixing roller, and at least one belt support roller is heated to form a heat roller And at least one heat roller may be displaced to a pressing position that presses the fixing roller via the endless belt and a non-pressing position that is spaced from the fixing roller and does not press the fixing roller via the endless belt. A displacement mechanism that is movably supported on each of a pair of side walls arranged to face each other with a space therebetween, and both of the heat rollers. Each of the bearing member, the end of which is rotatably supported, the driving means capable of displacing each of the bearing members in the direction in which the heat roller approaches and separates from the outer peripheral surface of the fixing roller, and each of the bearing members And a spring means for constantly urging the heat roller in a direction away from the outer peripheral surface of the fixing roller, and the drive means prevents the movement of the bearing member by the urging means in the direction of separation. A fixing device comprising: a cam member disposed in contact with each of the cam members; and a rotation unit that is disposed corresponding to each of the cam members and rotates each of the cam members. Provided.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of a fixing device configured according to the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 1, an embodiment of a fixing device configured in accordance with the present invention includes a fixing roller 2, a pressure roller 4 pressed against the fixing roller 2 from below, and a plurality of them arranged at intervals. In the embodiment, two belt support rollers 6 and 8 and an endless belt 10 wound around each of the belt support rollers 6 and 8 are provided. A part of the outer peripheral surface of the endless belt 10 is in pressure contact with a part of the outer peripheral surface of the fixing roller 2. A part of the outer peripheral surface of the endless belt 10 is brought into pressure contact with a part of the outer peripheral surface of the fixing roller 2 to form a nip region 10N.

The at least one belt support roller is configured to be heated by heating means disposed inside or outside. In the embodiment, one belt support roller 6 is composed of a heat roller in which a heating means 6H is built. In the following description, the belt support roller 6 may be referred to as a heat roller 6. In a space surrounded by the endless belt 10, the heat roller 6, and the belt support roller 8, a temperature sensor that is a control device for controlling the temperature of the heat roller 6, specifically, a thermistor S, is provided on the outer periphery of the heat roller 6. It is arrange | positioned so that a surface may be contacted. The paper P is conveyed substantially horizontally from right to left in FIG.

1 to 3, the fixing device includes a housing (not shown) including a pair of side walls 12 arranged to face each other in parallel with a space therebetween (in FIG. 2, one housing is not shown). Only the side wall 12 is shown). The fixing roller 2, the pressure roller 4, and the belt support roller 8 are rotatably supported between the side walls 12 and parallel to each other. The thermistor S is attached to a support frame (not shown) arranged to extend between the side walls 12. The heat roller 6 is disposed on each of the side walls 12 by a displacement mechanism 20 to be described later and presses the fixing roller 2 via the endless belt 10 (position shown in FIG. 1). 1 is moved to a non-pressing position (position shown in FIGS. 4 and 5) that is separated upward and does not press the fixing roller 2 via the endless belt 10. The belt support roller 8 is arranged on the outer side of the outer peripheral surface of the fixing roller 2 on the downstream side (right side in FIG. 1) on the downstream side (right side in FIG. 1) in the rotational direction of the fixing roller 2 (clockwise in FIG.

When the fixing roller 2 is viewed in the axial direction (in FIG. 1, the paper surface is viewed from the front to the back), the virtual horizontal line passing through the axis of the fixing roller 2 is orthogonal to the x axis through the axis of the fixing roller 2 When the virtual vertical line to be used is the y-axis, the belt support roller 6 that is a heat roller has the above-described displacement mechanism 20 with respect to the outer peripheral surface of the fixing roller 2 as described above by the displacement mechanism 20 described later in the second quadrant. It can be displaced vertically between the pressed position and the non-pressed position. On the other hand, in the first quadrant, the belt support roller 8 is on the downstream side in the rotation direction of the fixing roller 2 with respect to the belt support roller 6 and on the upstream side in the transport direction of the paper P, and is spaced outside the outer peripheral surface of the fixing roller 2. Is placed.

The fixing roller 2 is arranged so that a driving gear 2G can rotate integrally (see FIG. 2). The driving gear 2G is connected to an electric motor M1 that is a driving source via a power transmission mechanism including other gears (not shown). Drive coupled. The belt support roller 8 is disposed so that a driven gear (not shown) can rotate integrally. The driven gear is engaged with the driving gear 2G of the fixing roller 2 via another gear (not shown).

The fixing roller 2 and the pressure roller 4 are made of metal, for example, SUS or iron mandrel, solid silicon rubber or foamed silicon rubber which is an elastic member covering the mandrel, and PFA tube covering the silicon rubber or foamed silicon rubber. It can consist of Instead of the configuration in which the outer peripheral surface of the silicon rubber or the foamed silicon rubber is covered with the PFA tube, the outer peripheral surface of the silicon rubber or the foamed silicon rubber may be coated with a fluororesin that is a toner release layer. The belt supporting rollers 6 and 8 are made of a hollow tube made of metal such as SUS or aluminum. The endless belt 10 can be formed from polyimide resin, Ni, or SUS. The heating means 6H is composed of a halogen heater. In the following description, the heating means 6H may be referred to as a halogen heater 6H. There are other embodiments in which the heating means 6H is constituted by other heating means, for example, an exciting coil (IH coil) for electromagnetic induction heating, instead of the halogen heater. In the case where the heating means is composed of an IH coil, there is an embodiment in which the IH coil is arranged so as to cover a part of the outer peripheral surface of the belt support roller 6 with a gap from the outside.

As described above, in the fixing device, the heat roller 6 is pressed from the fixing roller 2 via the endless belt 10 (the position shown in FIG. 1), and the endless belt 10 is separated from the fixing roller 2. Is provided with a displacement mechanism 20 that can be displaced to a non-pressing position (a position shown in FIGS. 4 and 5) that does not press the fixing roller 2. The displacement mechanism 20 is supported by each of the pair of side walls 12 so as to be movable (in the embodiment, freely movable up and down), and both ends of the heat roller 6 are rotatably supported, and a bearing member The heat roller 6 can be displaced in the vertical direction in which the heat roller 6 approaches and separates from the outer peripheral surface of the fixing roller 2 and the bearing member 22. Spring means for always urging in a direction away from the outer peripheral surface (upward in the embodiment), and a compression coil spring 29 in the embodiment. The drive means 23 is arranged corresponding to each of the cam members 26 and the cam members 26 disposed in contact with the bearing members 22 so as to prevent the compression coil springs 29 from moving in the separating direction. And rotating means for rotating each of the cam members 26.

1 to 5, only the bearing member 22, the drive means 23, the compression coil spring 29 and the like disposed on one side wall 12 are shown in the displacement mechanism 20, and the displacement mechanism 20 is arranged on the other side wall 12. The provided bearing member 22, drive means 23, compression coil spring 29, etc. are not shown. Each of the bearing members 22 disposed on each of the side walls 12, each of the driving means 23 (excluding a spring clutch described later), each of the compression coil springs 29, etc. have substantially the same configuration and layout. Therefore, hereinafter, the one bearing member 22, the driving means 23, the compression coil spring 29, and the like disposed on the one side wall 12 will be described. The drive means 23 provided on the other side wall 12 is not provided with a spring clutch 36 described later.

Referring to FIGS. 1 to 3, one side wall 12 is formed with a vertically elongated rectangular hole 12a extending vertically, and a bearing member 22 is held in the elongated hole 12a so as to be movable up and down. Has been. The bearing member 22 is composed of a vertically long block body having a substantially rectangular parallelepiped shape. A bearing hole 22a is formed in the bearing member 22, and one end portion (right end portion in FIG. 1) of the heat roller 6 is rotatably supported in the hole 22a via a bearing (not shown). The axis of the heat roller 6 is parallel to the axes of the belt support roller 8, the fixing roller 2, and the pressure roller 4. The upper end surface of the bearing member 22 forms a horizontal plane and constitutes a cam follower 22b that is a contact portion with a cam member 26 described later. Although not shown, one end of the halogen heater 6H is supported by one bearing member 22 in a stationary state.

One end of a shaft 24 is rotatably supported on one side wall 12 and above the bearing member 22. The axis of the shaft 24 is parallel to the axis of the heat roller 6. A cam member 26 and a gear 28 that constitute a part of the driving means 23 are fixed to the shaft 24. The cam member 26 is formed of a block body having a substantially rectangular shape when viewed in the axial direction, and includes four cam surfaces 26a, 26b, 26c and 26d. In the four cam surfaces 26a to 26d, each of the cam surfaces adjacent to each other in the circumferential direction is arranged on a plane orthogonal to each other, and an arc is formed between each of the cam surfaces 26a to 26d adjacent to each other in the circumferential direction. It is made continuous by the surface. The cam surfaces 26a, 26b, 26c and 26d are arranged in this order in the counterclockwise direction in FIG. 1, and the distance from the axis of the shaft 24 is decreased in this order. In FIG. 1, the cam surface 26a having the longest distance from the shaft center of the shaft 24 is positioned at the lowermost end. In this state, the cam surface 26a is positioned on a horizontal plane.

The bearing member 22 is always urged in a direction (vertically upward in the embodiment) in which the heat roller 6 is separated from the outer peripheral surface of the fixing roller 2 at one side wall 12 and directly below the bearing member 22. In the embodiment, a compression coil spring 29 is provided. The lower end of the compression coil spring 29 is held by a spring holder (not shown) disposed on one side wall 12, and the upper end is pressed against the horizontal lower surface of the bearing member 22, so that the bearing member 22 is moved vertically upward. Energized. The bearing member 22 is moved upward along the elongated hole 12a in the elongated hole 12a of the one side wall 12, and the cam follower 22b is viewed from below one cam surface of the cam member 26, that is, the cam surface 26a in FIG. The compression coil spring 29 is pressed by the spring force.

One side of the shaft 30 is rotatably supported on one side wall 12. The shaft 30 is arranged in parallel to the shaft 24 with a space leftward in the horizontal direction in FIG. Gears 32 and 34 are disposed on the shaft 30 at intervals in the axial direction. The gear 32 is rotatably supported by the shaft 30 and is drivingly coupled to an electric motor M2 that is a driving source via a power transmission mechanism including another gear (not shown). The gear 34 is fixed to the shaft 30 so as to rotate integrally with the shaft 30 and is meshed with the gear 28. The structures of the gears 32 and 34 themselves (tooth shape, number of teeth, pitch circle, etc.) have substantially the same shape and size. The number of teeth of the gear 28: the number of teeth of the gear 34 = 2: 1.

The gears 32 and 34 are connected via a spring clutch 36 that may utilize a well-known configuration. As shown in FIG. 3, the spring clutch 36 includes boss portions 32a and 34a formed on the gears 32 and 34, respectively, and having outer peripheral surfaces having the same outer diameter. Boss portions 32a and 34a butted so as to rotate, a coil spring 38 fitted over the outer peripheral surfaces of the boss portions 32a and 34a, and a cylindrical shape fitted to the outer peripheral surface of the coil spring 38 The stop ring 40 is provided. One end of the coil spring 38 is locked to one end of the stop ring 40 so as not to be relatively rotated, and the other end of the coil spring 38 is locked to the boss portion 34a of the gear 34 so as not to be relatively rotated. On the outer peripheral surface of the stop ring 40, a locked piece 42 extending outward in the radial direction is integrally provided. The locked surface 42a (see FIG. 6) of the locked piece 42 facing the rotation direction of the shaft 30 (counterclockwise in FIG. 1) is the axis of the shaft 30 when viewed in the axial direction of the shaft 30. It is positioned on a plane extending in the radial direction. Since the drive means 23 in the displacement mechanism 20 disposed on the other side wall 12 is not provided with the spring clutch 36, the gear 34 is only fixed to the other end of the shaft 30.

A shaft 44 is fixed in parallel to the shaft 30 at one of the side walls 12 at a position vertically above the shaft 30. A stopper 50 is rotatably supported on the shaft 44. The stopper 50 is fork-shaped downward from a cylindrical boss portion 52 that is rotatably fitted to the shaft 44 and a position on the outer peripheral surface of the boss portion 52 that faces each other in the radial direction across the shaft center. 1 and a pair of stop arms 54 and 56 extending to the top, and a locked arm 58 extending upward from the upper end in FIG.

The plate-like locked arm 58 is formed with a locked groove 58a extending downward from the upper end. The stop arms 54 and 56 respectively extend obliquely downward from the outer peripheral surface of the boss portion 52 in a direction away from each other in FIG. 1 and then extend downward in parallel with each other. A lower end surface 54a (see FIGS. 4 and 7) of the stop arm 54 is on a horizontal plane passing through the axis of the shaft 30 at a position close to the right outer side in FIG. 1 with respect to the outer peripheral surface of the stop ring 40 of the spring clutch 36. Is positioned. The lower end surface 54 a of the stop arm 54 is positioned at a position facing the locked surface 42 a on the rotation locus of the locked piece 42 in the stop ring 40. On the other hand, the lower end portion 56a of the stop arm 56 extends substantially horizontally toward the outer peripheral surface of the stop ring 40 at a position spaced to the left outer side in FIG. An upper surface 56b in FIG. 1 of the lower end portion 56a is substantially on a horizontal plane passing through the axis of the shaft 30. The front end surface 56c (see FIG. 6) of the lower end portion 56a of the stop arm 56 is positioned at a predetermined interval with respect to the outer peripheral surface of the stop ring 40 (more specifically, the engagement in the stop ring 40). It is positioned on the outer side in the radial direction so as not to interfere with the rotational movement of the locked piece 42 with respect to the rotation locus of the stop piece 42).

A solenoid SOL that is an actuator for rotating the stopper 50 is disposed on one side wall 12 on the right side of the locked arm 58 in the stopper 50 in FIG. The solenoid SOL includes a movable iron core 60 extending leftward in FIG. 1, and a locking pin 62 is fixed to a distal end portion of the movable iron core 60 so as to extend radially outward from the outer peripheral surface thereof. . The locking pin 62 is orthogonal to the axis of the movable iron core 60 and is parallel to the shaft 44, and the distal end is engaged with the locked groove 58 a of the locked arm 58 in the stopper 50 so as to be relatively movable. Yes. As the actuator, there is another embodiment configured by a fluid pressure cylinder mechanism, for example, an air cylinder mechanism, instead of the solenoid SOL.

The self-holding solenoid SOL rotates the stopper 50 alternately around the shaft 44 in the opposite direction for each ON operation, and the first position shown in FIGS. 1, 5, and 6, and FIGS. 7 and alternately held at the second position shown in FIG. When the stopper 50 is positioned at the first position shown in FIGS. 1, 5, and 6, the stop arm 54 has its lower end portion approaching the outer peripheral surface of the stop ring 40, and its lower end surface 54 a is in the stop ring 40. On the rotation trajectory of the locked piece 42, it is positioned at a position where the rotational movement is interfered with the locked surface 42 a of the locked piece 42. On the other hand, the end surface 56c of the lower end 56a of the stop arm 56 is separated from the outer peripheral surface of the stop ring 40, and the upper surface 56b of the lower end 56a in FIG. It retracts to the outside in the direction and is positioned at a position where it does not interfere with the rotational movement of the locked piece 42.

When the stopper 50 is positioned at the second position shown in FIGS. 4 and 7, the lower end of the stop arm 54 is separated from the outer peripheral surface of the stop ring 40, and the lower end surface 54 a is engaged with the stop ring 40. With respect to the rotation trajectory of the stop piece 42, the stop piece 42 is positioned outside in the radial direction so as not to interfere with the rotational movement of the locked piece 42. On the other hand, the end surface 56c of the lower end 56a of the stop arm 56 approaches the outer peripheral surface of the stop ring 40, and the upper surface 56b of the lower end 56a in FIG. On the trajectory, it is positioned at a position that opposes the locked surface 42a of the locked piece 42 and interferes with the rotational movement of the locked piece 42. The gear 28, gear 32, gear 34, electric motor M2, spring clutch 36, stopper 50, solenoid SOL, etc. constitute rotating means.

The fixing device includes a controller 70 that controls the operation of the fixing device including the displacement mechanism 20. The controller 70 is constituted by a microcomputer, and includes a central processing unit (CPU) that performs arithmetic processing according to a control program, a ROM that stores a control program, a readable / writable RAM that stores arithmetic results, a timer, a counter, an input interface, It has an output interface. The input interface of the controller 70 thus configured includes an image forming machine provided with a thermistor S, other detectors, and a fixing device, for example, a copy switch SW ( Therefore, detection signals from other switches and the like are input, and control signals are output from the output interface to the electric motors M1 and M2, the solenoid SOL, and the like. The fixing device is disposed in the main body of the copying machine (not shown). However, the fixing device may be controlled by a controller that controls the operation of the entire copying machine disposed in the main body of the copying machine.

1 and 6, the stopper 50 of the displacement mechanism 20 is positioned at the first position. The locked surface 42 a of the locked piece 42 of the stop ring 40 in the spring clutch 36 is positioned in contact with the lower end surface 54 a of the stop arm 54. The cam member 26 has a cam surface 26 a having the longest distance from the shaft 26 a at the lower end, and a cam follower 22 b of the bearing member 22 is pressed against the cam surface 26 a by a compression coil spring 29. The heat roller 6 is positioned at a pressing position that presses the outer peripheral surface of the fixing roller via the endless belt 10.

When the solenoid SOL is turned on in the state shown in FIGS. 1 and 6, the stopper 50 of the displacement mechanism 20 is rotated around the shaft 44 counterclockwise in FIGS. 1 and 6 to the second position. Positioned (see FIGS. 4 and 7). Subsequently, the electric motor M2 is operated to rotate the gear 32 (see FIG. 3) in the counterclockwise direction in FIG. Since the lower end surface 54a of the stop arm 54 is retracted to the outside in the radial direction of the rotation trajectory that does not interfere with the rotation of the locked surface 42a of the locked piece 42 in the stop ring 40 of the spring clutch 36, The rotation of the stop ring 40 is free. As a result, the spring clutch 36 is in a connected state, and the coil spring 38, the gear 34, and the stop ring 40 are integrally rotated in the same direction as the gear 32. When the stop ring 40 is rotated 180 °, the locked surface 42a of the locked piece 42 of the stop ring 40 is brought into contact with the upper surface 56b of the lower end portion 56a of the stop arm 56 (see FIG. 7). The rotation of the stop ring 40 is prevented. As a result, the spring clutch 36 is disengaged and the gear 32 is idled.

When the gear 34 is rotated 180 ° together with the stop ring 40, the gear 28 and the cam member 26 engaged with the gear 34 are rotated by 90 ° clockwise in FIG. 1 and stopped (see FIG. 4). In the cam member 26, the cam surface 26b whose distance from the shaft center of the shaft 24 is smaller than the cam surface 26a is positioned at the lower end. Therefore, the bearing member 22 is moved from the position shown in FIG. It is moved upward by the difference in the distance to the position shown. The heat roller 6 is separated from the outer peripheral surface of the fixing roller 2 from the pressing position (the position shown in FIG. 1) that presses the outer peripheral surface of the fixing roller 2 via the endless belt 10. Is not moved to a non-pressing position (position shown in FIG. 4). The nip width of the nip region 10N at the non-pressing position shown in FIG. 4 is smaller than the nip width of the nip region 10N at the pressing position shown in FIG.

When the solenoid SOL is turned on in the state shown in FIGS. 4 and 7, the stopper 50 of the displacement mechanism 20 is rotated around the shaft 44 in the clockwise direction in FIGS. 4 and 7, and again to the first position. Positioned (see FIGS. 5 and 6). Subsequently, the electric motor M2 is operated to drive the gear 32 (see FIG. 3) to rotate counterclockwise in FIG. The upper surface 56b of the lower end portion 56a of the stop arm 56 is retracted to the outside in the radial direction of the rotation trajectory that does not interfere with the rotation of the locked surface 42a of the locked piece 42 in the stop ring 40 of the spring clutch 36. Therefore, the rotation of the stop ring 40 is free. As a result, the spring clutch 36 is in a connected state, and the coil spring 38, the gear 34, and the stop ring 40 are integrally rotated in the same direction as the gear 32. When the stop ring 40 is rotated 180 °, the locked surface 42a of the locked piece 42 in the stop ring 40 is brought into contact with the lower end surface 54a of the stop arm 54 (see FIG. 6). Is prevented from rotating. As a result, the spring clutch 36 is disengaged and the gear 32 is idled.

When the gear 34 is rotated 180 ° together with the stop ring 40, the gear 28 and the cam member 26 engaged with the gear 34 are rotated 90 ° clockwise in FIG. 4 and stopped (see FIG. 5). In the cam member 26, the cam surface 26c whose distance from the axis of the shaft 26 is smaller than the cam surface 26b is positioned at the lower end. Therefore, the bearing member 22 is moved from the position shown in FIG. It is moved upward by the difference in the distance to the position shown. The heat roller 6 is separated from the outer peripheral surface of the fixing roller 2 from a non-pressing position (a position shown in FIG. 4) where the fixing roller 2 is not pressed via the endless belt 10 apart from the outer peripheral surface of the fixing roller 2. It is displaced to the pressing position (position shown in FIG. 5). The nip width of the nip region 10N at the non-pressing position shown in FIG. 5 is further smaller than the nip width of the nip region 10N at the non-pressing position shown in FIG.

When the solenoid SOL is turned on in the state shown in FIGS. 5 and 6, the stopper 50 of the displacement mechanism 20 is again positioned at the second position (see FIG. 7). Subsequently, when the electric motor M2 is operated to rotate the gear 32 (see FIG. 3) in the counterclockwise direction in FIG. 5, the cam member 26 is shown in FIG. Since the cam surface 26d, which is rotated by 90 ° clockwise from the position shown in the figure and the distance from the shaft center of the shaft 24 is smaller than the cam surface 26c, is positioned at the lower end, the bearing member 22 is moved by the compression coil spring 29. The position is moved upward from the position shown in FIG. 5 by a difference in the distance. The heat roller 6 is separated from the outer peripheral surface of the fixing roller 2 from a non-pressing position (position shown in FIG. 5) that is separated from the outer peripheral surface of the fixing roller 2 and does not press the fixing roller 2 via the endless belt 10. It is displaced to a pressing position (not shown). The nip width of the nip region 10N at a non-pressing position (not shown) is further smaller than the nip width of the nip region 10N at the non-pressing position shown in FIG.

As described above, according to the fixing device of the present invention, the transmission mechanism 20 causes at least one heat roller, in the embodiment, one heat roller 6 to pass through the endless belt 10 on the outer peripheral surface of the fixing roller 2. The pressing position can be shifted to the pressing position and the non-pressing position where the outer peripheral surface of the fixing roller 2 is not pressed via the endless belt 10 apart from the fixing roller 2. As a result, the surface of the fixing roller 2, in the embodiment, the surface of silicon rubber is permanently deformed (permanent distortion) compared to a fixing device in which the heat roller is held in a state of being constantly pressed against the fixing roller via an endless belt. Therefore, the life of the fixing roller 2 can be ensured as required. In addition, it is possible to raise the surface temperature of the fixing roller 2 to a fixable temperature in a relatively short time compared to a fixing device in which the heat roller is separated from the fixing roller and is not constantly pressed (separated state). To.

The controller 70 presses at least one heat roller, in the embodiment, one heat roller 6 to a pressing position (position shown in FIG. 1) while the rotation driving of the fixing roller 2 and the endless belt 10 is stopped. While the positioning roller 2 and the endless belt 10 are rotationally driven, the displacement mechanism 20 is preferably controlled so as to be positioned at a non-pressing position (position shown in FIG. 4). In the illustrated embodiment, the nip width of the nip region 10N when the heat roller 6 is positioned at the pressing position (position shown in FIG. 1) is set in advance to a nip width suitable for the fixing operation.

When the fixing roller 2 is rotated clockwise in FIG. 4 by the electric motor M1 in a state where the heat roller 6 is positioned at the non-pressing position (position shown in FIG. 4), the pressure roller 4 is driven counterclockwise. Be made. At the same time, the belt support roller 8 is also driven to rotate counterclockwise by the fixing roller 2, so that the heat roller 6 is driven to rotate counterclockwise in FIG. When the halogen heater 6H is energized and heat generation is started, the heat from the halogen heater 6H is transmitted to the heat roller 6, and the heat transmitted to the heat roller 6 is transmitted to the fixing roller 2 via the endless belt 10. Therefore, the temperature rise of the fixing roller 2 is started. The heat transmitted to the fixing roller 2 is also transmitted to the pressure roller 4. After the surface temperature of the fixing roller 2 reaches a predetermined temperature from room temperature, the sheet P on which the toner is transferred on one side (upper surface) is conveyed substantially horizontally from right to left in FIG. After passing through the nip portion of the roller 4, the unfixed toner transferred to one side of the paper P is melted and fixed on one side of the paper P by the fixing roller 2. As described above, according to the fixing device, the heat roller 6 is operated while the fixing roller 2 and the endless belt 10 are rotationally driven (generally, during the printing operation as described above, or during warm-up). ) Is positioned at the non-pressing position (the position shown in FIG. 4), and the permanent roller (permanent distortion) hardly occurs on the surface of the fixing roller 2, in the embodiment, the surface of the silicone rubber. It can be secured as follows.

The heat roller 6 is positioned at the pressing position (the position shown in FIG. 1) while the rotational driving of the fixing roller 2 and the endless belt 10 is stopped (generally during fixing standby). In this state, when the halogen heater 6H is energized to generate heat, the heat roller 6 is heated. The heat of the heat roller 6 is directly transmitted to the fixing roller 2 through the endless belt 10. As a result, a decrease in the surface temperature of the fixing roller 2 can be suppressed as compared with a fixing device in which the heat roller is separated from the fixing roller and is not constantly pressed (separated state). It is possible to raise the surface temperature to a fixable temperature in a relatively short time.

In the fixing device, the controller 70 positions at least one heat roller, in the embodiment, one heat roller 6 at a non-pressing position (position shown in FIG. 4) during the printing operation, and performs the printing operation. It is preferable to control the displacement mechanism 20 so as to be positioned at the pressing position (position shown in FIG. 1) during other states (generally during fixing standby or warm-up) except during the period of time. As described above, the surface of the fixing roller 2, the embodiment, because the heat roller 6 is positioned at the non-pressing position (the position shown in FIG. 4) while the printing operation is performed. Since the permanent deformation (permanent distortion) hardly occurs on the surface of the silicon rubber, the life of the fixing roller 2 can be ensured as required. Further, the heat roller 6 is positioned at the pressing position (the position shown in FIG. 1) during other states (generally during fixing standby or warm-up) except during the printing operation. As described above, the lowering of the surface temperature of the fixing roller 2 can be suppressed as compared with that in which the heat roller is kept away from the fixing roller and not always pressed (separated state) and heated. Therefore, it is possible to raise the surface temperature of the fixing roller 2 to a fixable temperature in a relatively short time.

The controller 70 is configured such that at least one heat roller, in the embodiment, one heat roller 6 is positioned at the pressing position (the position shown in FIG. 1), and the fixing roller 2 and the endless belt 10 (the fixing roller 2 and the endless belt). In addition to the belt support rollers 6 and 8 and the pressure roller 4 in addition to 10, the rotation drive is stopped, and at least one heat roller, in the embodiment, one heat. It is preferable to control the fixing device so that the surface temperature of the roller 6 is maintained at a predetermined value or more and the fixing roller 2 and the endless belt 10 are rotationally driven every predetermined time for a predetermined time. A state in which the surface temperature of the heat roller 6 is maintained at a predetermined value or more in a state where the heat roller 6 is positioned at the pressing position (the position shown in FIG. 1) and the rotation driving of the fixing roller 2 and the endless belt 10 is stopped. If left for a long time, permanent deformation (permanent distortion) is likely to occur in the pressing portion on the surface of the fixing roller 2, in the embodiment, the pressing portion on the surface of silicon rubber. Therefore, by rotating the fixing roller 2 and the endless belt 10 for a predetermined time every predetermined time, the position of the pressing portion can be changed in the circumferential direction, and the occurrence of the permanent deformation (permanent distortion) is prevented. It becomes possible to do.

The displacement mechanism 20 includes at least one heat roller, in the embodiment, one heat roller 6, a plurality of non-pressing positions at different distances from the fixing roller 2 (in the embodiment, FIG. 4 and FIG. 5). The position of the outer peripheral surface of the endless belt 10 may be pressed against the partial region of the outer peripheral surface of the fixing roller 2. It is preferable that the nip width of the nip region 10 </ b> N formed by the above becomes smaller as the heat roller 6 is positioned at a non-pressing position where the distance away from the fixing roller 2 is larger. As a result, the controller 70 can appropriately change the nip width as necessary, and a more suitable fixing operation or fixing preparation operation can be performed.

The controller 70 has a larger distance for separating at least one heat roller, in the embodiment, one heat roller 6 from the fixing roller 2 than a non-pressing position (position shown in FIG. 4) during a normal printing operation. Printed in a non-pressing position (in the embodiment, the position shown in FIG. 5 or another non-pressing position not shown previously) and the nip width is set smaller than that during normal printing operation. It is preferable to perform the operation. The heat roller 6 is positioned at a non-pressing position where the distance away from the fixing roller 2 is larger than the non-pressing position (position shown in FIG. 4) during the normal printing operation, and the nip width is larger than that during the normal printing operation. Is set to a smaller value, a larger temperature difference is provided between the outer surface of the endless belt 10 and the surface (outer peripheral surface) of the fixing roller 2 so that the toner adhering to the endless belt 10 is applied to the surface of the fixing roller 2. It becomes possible to make it easy to move. As a result, for example, when the printing operation is performed after the jam processing, the toner attached to the endless belt 10 when the jam processing is performed is moved to the surface of the fixing roller 2. The toner moved to the fixing roller 2 is removed from the surface of the fixing roller 2 by being fixed on a sheet passing through the nip portion between the fixing roller 2 and the pressure roller 4. As a result, the endless belt 10 is automatically cleaned in the normal printing operation process without providing any special cleaning means on the endless belt 10. Note that the amount of the toner moved from the surface of the fixing roller 2 to the surface of the paper is very small, and does not cause the paper to be recognized by the naked eye.

A cleaning mode is provided in which the paper P can pass through the fixing device during a non-printing operation, and the controller 70 does not press at least one heat roller, in the embodiment, one heat roller 6 during a normal printing operation. The nip width is set at a non-pressing position (FIG. 5 or other non-pressing position not shown in the above description) where the distance from the fixing roller 2 is larger than the position (position shown in FIG. 4). It is preferable to execute the cleaning mode in a state set smaller than that during operation. The execution of the cleaning mode can be performed by the operator each time, for example, by periodically displaying the execution of the cleaning mode on an operation panel of a copying machine (not shown). In addition, by allowing the execution of the cleaning mode to be freely set on the operation panel, the operator or serviceman can arbitrarily select the execution time. The execution of the cleaning mode may be controlled so that one or a plurality of sheets pass through the fixing device while the fixing roller 2 and the endless belt 10 are rotationally driven without performing a printing operation. As a result, the endless belt 10 can be cleaned without providing any special cleaning means for the endless belt 10.

The displacement mechanism 20 is movably supported on each of the pair of side walls 12 arranged so as to face each other with a gap therebetween, and a bearing member 22 in which both ends of the heat roller 6 are rotatably supported, Each of the bearing members 22 is preferably provided with driving means 23 that can displace the heat roller 6 in a direction in which the heat roller 6 approaches and separates from the outer peripheral surface of the fixing roller 2. Such a configuration contributes to practically and reliably achieving the above effects.

The displacement mechanism 20 includes spring means that constantly urges each of the bearing members 22 in a direction in which the heat roller 6 is separated from the outer peripheral surface of the fixing roller 2, in the embodiment, a compression coil spring 29. A cam member 26 disposed in contact with each of the bearing members 22 so as to prevent the compression coil spring 29 from moving in the separating direction, and a cam member 26 disposed corresponding to each of the cam members 26. It is preferable that a rotation means for rotating each of the members 26 is provided. Such a configuration contributes to achieving the above-described effects more reliably in practical use.

The fixing device is provided with a displacement mechanism 20 that can displace one heat roller 6 between the pressing position and the non-pressing position. However, two or more heat rollers, for example, the heat roller 6 are provided. In addition, there is another embodiment including a displacement mechanism that can displace the heat roller 8 (when the belt support roller 8 is configured from a heat roller) to the pressing position and the non-pressing position, respectively.

According to the fixing device according to the present invention, a partial region of the outer peripheral surface of the endless belt 10 is configured to be in pressure contact with a partial region of the outer peripheral surface of the fixing roller 2. That is, the flexible endless belt 10 is pressed and formed along a partial region of the outer peripheral surface of the fixing roller 2 to form the nip region 10N, so that the nip width for heating the fixing roller 2 is significantly larger than the conventional one. Can be increased. As a result, the heating time of the fixing roller 2 can be shortened and the warm-up time of the fixing device can be shortened without increasing the local load on the fixing roller 2 and without impairing the durability of the fixing roller 2. Can do.

1 is a schematic configuration diagram illustrating an embodiment of a fixing device according to the present invention. FIG. 2 is a cross-sectional view showing a main part of a displacement mechanism provided in the fixing device shown in FIG. 1. FIG. 3 is a partial view of the displacement mechanism shown in FIG. 2, and is a partial view showing a spring clutch in section. FIG. 6 is a schematic configuration diagram illustrating another operation mode of the fixing device illustrated in FIG. 1. FIG. 10 is a schematic configuration diagram illustrating still another operation mode of the fixing device illustrated in FIG. 1. It is the elements on larger scale which show the positional relationship of the stopper shown in FIG. 1, and the stop ring of a spring clutch. It is the elements on larger scale which show the positional relationship of the stopper shown in FIG. 4, and the stop ring of a spring clutch.

Explanation of symbols

2: Fixing roller 4: Pressure roller 6: Belt support roller (heat roller)
6H: Heating means (halogen heater)
8: Belt support roller 10: Endless belt 10N: Nip region 12: Side wall 20: Displacement mechanism 22: Bearing member 23: Drive means 29: Compression coil spring 36: Spring clutch 40: Stop ring 42: Locked piece 42a: Covered Locked surface 50: Stopper 54: Stop arm 54a: Stop arm lower end surface 56: Stop arm 56a: Stop arm lower end portion 56b: Stop arm lower end portion upper surface 56c: Stop arm lower end portion Front end surface 70: Controllers M1, M2: Electric motor SOL: Solenoid P: Paper S: Thermistor

Claims (9)

In a fixing device including a fixing roller and a pressure roller pressed against the fixing roller, a plurality of belt support rollers arranged at intervals from each other, and an outer peripheral surface wound around each of the belt support rollers An endless belt whose partial area is pressed against a partial area of the outer peripheral surface of the fixing roller, heating means for heating at least one belt support roller to be a heat roller, and at least one heat roller, A displacement mechanism that can be displaced to a pressing position that presses the fixing roller via the endless belt, and a non-pressing position that is spaced apart from the fixing roller and does not press the fixing roller via the endless belt; and a controller that controls the device; It is equipped et al is,
The controller positions at least one heat roller in a pressing position while the rotation driving of the fixing roller and the endless belt is stopped, and positions it in a non-pressing position while the fixing roller and the endless belt are driven to rotate.
A fixing device. In a fixing device including a fixing roller and a pressure roller pressed against the fixing roller, a plurality of belt support rollers arranged at intervals from each other, and an outer peripheral surface wound around each of the belt support rollers An endless belt whose partial area is pressed against a partial area of the outer peripheral surface of the fixing roller, heating means for heating at least one belt support roller to be a heat roller, and at least one heat roller, A displacement mechanism that can be displaced to a pressing position that presses the fixing roller via the endless belt, and a non-pressing position that is spaced apart from the fixing roller and does not press the fixing roller via the endless belt; and a controller that controls the device; Is provided,
Controller is at least one of the heat roller, while the printing operation is performed positioned in the non-pressing position, while the other state except during the printing operation is performed positioned at the pressing position,
A fixing device. The controller holds the surface temperature of at least one heat roller at a predetermined value or more in a state where at least one heat roller is positioned at the pressing position and rotation of the fixing roller and the endless belt is stopped. The fixing device according to claim 1 , wherein the fixing roller and the endless belt are rotationally driven for a predetermined time every predetermined time. In a fixing device including a fixing roller and a pressure roller pressed against the fixing roller, a plurality of belt support rollers arranged at intervals from each other, and an outer peripheral surface wound around each of the belt support rollers An endless belt whose partial area is pressed against a partial area of the outer peripheral surface of the fixing roller, heating means for heating at least one belt support roller to be a heat roller, and at least one heat roller, A displacement mechanism capable of displacing a pressing position that presses the fixing roller via the endless belt and a non-pressing position that is spaced from the fixing roller and does not press the fixing roller via the endless belt;
The displacement mechanism can displace at least one heat roller to a plurality of non-pressing positions at different distances from the fixing roller, and a partial region of the outer peripheral surface of the endless belt is a part of the outer peripheral surface of the fixing roller. The nip width of the nip region formed by being pressed against the region becomes smaller as the at least one heat roller is positioned at a non-pressing position where the distance away from the fixing roller is larger.
A fixing device. A controller for controlling the apparatus is provided, and the controller positions at least one heat roller at a non-pressing position where the distance from the fixing roller is larger than the non-pressing position during a normal printing operation, and sets the nip width. The fixing device according to claim 4 , wherein the printing operation is executed in a state set smaller than that in a normal printing operation. A controller for controlling the apparatus is provided, and a cleaning mode is provided in which a sheet can pass through the fixing device during a non-printing operation. The controller fixes at least one heat roller more than a non-pressing position during a normal printing operation. The fixing device according to claim 4 , wherein the cleaning mode is executed in a state where the distance away from the roller is set at a non-pressing position where the distance is large and the nip width is set smaller than that in a normal printing operation. The displacement mechanism includes a bearing member that is movably supported on each of a pair of side walls that are arranged to face each other with a space therebetween, and that both ends of the heat roller are rotatably supported, and each of the bearing members The fixing device according to claim 4 , further comprising: a driving unit that can displace the heat rollers in directions toward and away from the outer peripheral surface of the fixing roller. The displacement mechanism includes spring means for constantly urging each of the bearing members in a direction in which the heat roller is separated from the outer peripheral surface of the fixing roller, and the drive means is moved by the urging means in the separated direction. to block comprises a cam member disposed in contact with each of the bearing member, and a rotating means for rotating each of each is disposed to correspond and cam member of the cam member, claim 8. The fixing device according to 7 . In a fixing device including a fixing roller and a pressure roller pressed against the fixing roller, a plurality of belt support rollers arranged at intervals from each other, and an outer peripheral surface wound around each of the belt support rollers An endless belt whose partial area is pressed against a partial area of the outer peripheral surface of the fixing roller, heating means for heating at least one belt support roller to be a heat roller, and at least one heat roller, A displacement mechanism capable of displacing a pressing position that presses the fixing roller via the endless belt and a non-pressing position that is spaced from the fixing roller and does not press the fixing roller via the endless belt;
The displacement mechanism includes a bearing member that is movably supported on each of a pair of side walls that are arranged to face each other with a space therebetween, and that both ends of the heat roller are rotatably supported, and each of the bearing members Each of the drive means that can displace the heat roller in a direction in which the heat roller approaches and separates from the outer peripheral surface of the fixing roller, and each of the bearing members in a direction in which the heat roller separates from the outer peripheral surface of the fixing roller. and a spring means for biasing, drive kinematic means by the urging means, so as to prevent movement in the direction of the separation, a cam member disposed in contact with each of the bearing members, each cam member And a rotating means for rotating each of the cam members.
A fixing device.

Images