Fixing device

Abstract

To provide a fixing device that can prevent leakage of lubricant from the ends of a film.SOLUTION: When a nip part forming member moves from a first position when a toner image is fixed to a second position moved in a first direction, a regulation unit regulates the movement in the first direction of a guide member, and thereby the relative position in the first direction of an inner surface of a film and an area of the nip part forming member facing the inner surface changes.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present invention relates to a fixing device mounted in an image forming apparatus such as a printer that forms a toner image on a recording material using an electrophotographic recording method. [Background technology]

[0002] One of the fixing devices installed in electrophotographic devices is a film heating type in which a recording material is sandwiched and conveyed between a cylindrical film and a pressure roller. One film heating type has a structure in which a ceramic heater is disposed in the internal space of the film, and the film is sandwiched between the ceramic heater and the pressure roller via the film (Patent Document 1). Other types include a structure in which a conductive layer is provided on the film to cause the film to generate heat through electromagnetic induction, and a structure in which a power supply terminal is brought into contact with the conductive layer of the film to supply power to the film to cause the film to generate heat.

[0003] In a fixing device using the film heating method, the inner surface of the film slides against a nip forming member such as a ceramic heater. For this reason, a lubricant such as heat-resistant grease is applied to the inner surface of the film. Since the film is cylindrical, the lubricant may leak from the end of the film and wrap around to the outer periphery of the film. If this lubricant adheres to the recording material, it may cause image defects.

[0004] Patent Document 1 discloses a configuration in which a film guide member that comes into contact with the inner surface of the film along the length of the film is provided with a groove that guides a lubricant to the center of the film in the length direction. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2008-146964 A Summary of the Invention [Problem to be solved by the invention]

[0006] Even if measures are taken to prevent the leakage of lubricant from the film guide, it is difficult to prevent the leakage of lubricant from the film edge. The main cause of the leakage of lubricant from the film edge is the lubricant present in the contact area between the inner surface of the film and the nip forming member and in the vicinity thereof moving to the edge due to capillary action.

[0007] An object of the present invention is to provide a fixing device capable of suppressing leakage of a lubricant from the edge of a film. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, the present invention provides a fixing device comprising a cylindrical film, a nip portion-forming member that contacts the inner surface of the film along the longitudinal direction of the film, a roller that contacts the outer peripheral surface of the film and forms a nip portion together with the nip portion-forming member via the film, and a guide member that is arranged opposite the inner surface of an end region of the film in the longitudinal direction and guides the rotation of the film, and which fixes a toner image formed on the recording material while nipping and transporting the recording material, the fixing device having a regulating portion that regulates movement of the guide member in a first direction that is perpendicular to the longitudinal direction and away from the roller, the nip portion-forming member is disposed to be movable in the first direction, and when the nip portion-forming member moves from a first position when the toner image is fixed to a second position moved in the first direction, the regulating portion regulates movement of the guide member in the first direction, thereby changing the relative position in the first direction between the inner surface of the film and the region of the nip portion-forming member that faces the inner surface. Effect of the Invention

[0009] According to the present invention, it is possible to provide a fixing device capable of suppressing leakage of a lubricant from the edge of a film. [Brief description of the drawings]

[0010] [Figure 1] FIG. [Diagram 2] FIG. 2 is a perspective view of the fixing device according to the first embodiment. [Diagram 3] FIG. 2 is a perspective view of the fixing device according to the first embodiment. [Figure 4] FIG. 2 is a cross-sectional view of the fixing device according to the first embodiment. [Diagram 5] FIG. 2 is a perspective view of a heater holder unit according to the first embodiment. [Figure 6] FIG. 2 is a perspective view of a heater holder unit according to the first embodiment. [Figure 7] FIG. 4 is a side view showing a pressing operation of the fixing device according to the first embodiment. [Figure 8] FIG. 2 is a side view of the fixing device according to the first embodiment. [Figure 9] FIG. 3 is a cross-sectional view illustrating the operation of the fixing device according to the first embodiment. [Figure 10] FIG. 11 is a perspective view of a fixing device according to a second embodiment. [Figure 11] FIG. 11 is a perspective view of a fixing device according to a second embodiment. [Figure 12] FIG. 11 is a side view of a fixing device according to a second embodiment. [Figure 13] 11 is a cross-sectional view illustrating the operation of a fixing device according to a second embodiment. [Figure 14] FIG. 11 is a perspective view illustrating the operation of a fixing device according to a third embodiment. [Figure 15] FIG. 11 is a cross-sectional view of a fixing device according to a third embodiment. [Figure 16] FIG. 11 is a cross-sectional view of a fixing device according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The following examples of the present invention will be illustrated with reference to the drawings. However, the dimensions, materials, shapes, and relative positions of the components described in these examples may be changed as appropriate depending on the configuration and various conditions of the device to which the invention is applied, and the scope of the present invention is not limited to the following embodiments.

[0012] Example 1 (Image forming device) FIG. 1 is a schematic cross-sectional view showing the configuration of an image forming apparatus 100. The image forming apparatus 100 of this embodiment is an electrophotographic image forming apparatus having a plurality of image forming units Sa to Sd. The first image forming unit Sa forms an image using yellow (Y), the second image forming unit Sb forms an image using magenta (M), the third image forming unit Sc forms an image using cyan (C), and the fourth image forming unit Sd forms an image using black (Bk) toner. These four image forming units are arranged in a line at regular intervals, and most of the configurations of the image forming units are substantially the same except for the color of the toner they contain. Therefore, in the following description, unless a particular distinction is required, the suffixes a, b, c, and d given to the reference numerals to indicate that the element is provided for one of the colors will be omitted and the description will be given generally.

[0013] The image forming section S has a photosensitive drum 1, a charging roller 2 that charges the photosensitive drum 1, a developing means 4, and a drum cleaning means 6. In this embodiment, the photosensitive drum 1, the charging roller 2, the developing means 4, and the drum cleaning means 6 are integrally formed into a cartridge to constitute a process cartridge 19 that is detachably attached to the main body of the image forming apparatus 100.

[0014] 1 at a predetermined process speed. The developing means 4 has a developing roller 41 for supplying toner to the photosensitive drum 1. The drum cleaning means 6 is a means for recovering the toner adhering to the photosensitive drum 1.

[0015] The scanner unit 3 emits a laser beam 18 corresponding to image information to the photosensitive drum 1, and scans the photosensitive drum 1 with the laser beam 18. As a result, an electrostatic latent image is formed on the surface of the photosensitive drum 1.

[0016] When an image forming operation is started by a control means (not shown) receiving an image signal, an electrostatic latent image corresponding to image information is formed on the photosensitive drum 1 of each image forming station S by charging with the charging roller 2 and scanning with the scanner unit 3. Next, the electrostatic latent image is developed by the developing roller 41, and a toner image is formed on the photosensitive drum 1.

[0017] The toner image formed on the photosensitive drum 1 of each image forming station S is transferred to the intermediate transfer belt 71 rotating in the direction of arrow R2 at the position of primary transfer station N1. As a result, four color toner images are superimposed on the intermediate transfer belt 71. The intermediate transfer belt 71 is stretched around three rollers, a drive roller 72, a tension roller 73, and a driven roller 74. The toner image on the photosensitive drum 1 is transferred to the intermediate transfer belt 71 by a voltage applied to a primary transfer roller 5. Toner remaining on the photosensitive drum 1 without being primarily transferred to the intermediate transfer belt 71 is removed by drum cleaning means 6.

[0018] The recording material P stored in the paper feed cassette 11 is fed by a paper feed roller 12 and then conveyed by a conveying roller 13. Then, at the secondary transfer portion N2, the toner image on the intermediate transfer belt 71 is transferred onto the recording material P. The toner image on the intermediate transfer belt 71 is transferred onto the recording material P by a voltage applied to a secondary transfer roller 8. Reference numeral 9 denotes a cleaner that cleans the intermediate transfer belt 71, and reference numeral 91 denotes a cleaning member that the cleaner 9 has.

[0019] The recording material P onto which the toner image has been transferred is conveyed to the fixing device 10, where it is subjected to a fixing process. The recording material P onto which the toner image has been fixed is discharged to the outside of the image forming apparatus 100.

[0020] (Fixing device) Next, the configuration of the fixing device 10 will be described. The fixing device 10 has a cylindrical film 106 and a heater 109 that is a nip portion forming member that contacts the inner surface of the film 106 along the longitudinal direction of the film 106. The fixing device 10 further has a pressure roller (roller) 102 that contacts the outer peripheral surface of the film 106 and forms a nip portion N together with the heater 109 via the film 106. The fixing device 10 further has flanges 111R and 111L that are disposed opposite the inner surface of the end region of the film 106 in the longitudinal direction of the film 106 and have guide portions (guide members) 111g that guide the rotation of the film 106. The toner image is fixed to the recording material P while sandwiching and conveying the recording material P on which the toner image has been formed at the nip portion N.

[0021] As will be described later, a unit having the heater 109, guide member 107, reinforcing stay 112, and support members 110R and 110L is referred to as a heater holder unit 119. Moreover, a unit in which the film 106 and flanges 111R and 111L are attached to the heater holder unit 119 is referred to as a film unit 101.

[0022] Fig. 2 is a perspective view of the fixing device 10 as seen from the upstream side in the conveying direction of the recording material P. Fig. 3 is a perspective view of the vicinity of a side plate 103R which is a part of the frame of the fixing device 10. The pressure roller 102 is made of a core metal with a silicone rubber layer and a fluororesin layer provided around it, and is rotatably attached to the side plates 103L and 103R via bearings. The pressure roller 102 rotates by the driving force of a motor (not shown).

[0023] The film unit 101 is biased toward the pressure roller 102 by compression springs 105L and 105R via pressure plates 104L and 104R. A nip portion N is formed by the biasing forces of the compression springs 105L and 105R. The recording material P is conveyed in the direction B shown in FIG. 2 while being sandwiched between the film unit 101 and the pressure roller 102, and is heated by the heat of a heater 109.

[0024] (Film unit) Next, the internal structure of the film unit 101 will be described with reference to Figures 3 to 6. Figure 4 is a cross-sectional view of the fixing device 10 at the center in the longitudinal direction of the film 106 (hereinafter also referred to as the film longitudinal direction or the pressure roller longitudinal direction), as viewed from the side plate 103L side toward the side plate 103R side. The view of the side plate 103L side from the side plate 103R side is substantially the same, so illustration and description of the side plate 103L side will be omitted.

[0025] As described above, film unit 101 has film 106, flanges 111R and 111L having guide portions (guide members) 111g that guide the rotation of film 106, and heater holder unit 119. Flanges 111R and 111L also have the function of restricting movement of film 106 in the film longitudinal direction.

[0026] Heater holder unit 119 has heater 109, guide member 107 that is disposed in the internal space of film 106 and rotatably supports film 106, and metallic reinforcing stay 112 with a U-shaped cross section that serves as a reinforcing member that reinforces guide member 107. Heater 109 is held by guide member 107.

[0027] Film 106 is a thin film tube with a base layer of PI (polyimide) having a thickness of about 30 to 100 μm, and the base layer is coated with a fluororesin such as PFA (tetrafluoroethylene-perfluoroalkylvinylether copolymer) via an adhesive layer. The materials and layer configurations of each layer of film 106 are not limited to those described above, and for example, a rubber layer such as silicone rubber may be provided between the base layer and the fluororesin layer.

[0028] The heater 107 is a plate-like member that is elongated in a direction perpendicular to the conveying direction B of the recording material P, and is formed by printing a heating resistor on a ceramic substrate. The heating resistor is covered with an insulating layer such as a glass layer. The heating resistor generates heat when power is supplied to the heating resistor.

[0029] 4, in the direction of arrow B, a heater 109 is housed in the center of guide member 107. A nip portion N is formed between heater 109 and pressure roller 102 via film 106. When pressure roller 102 is driven to rotate, film 106 is rotated in the direction of arrow C.

[0030] Heat-resistant grease is applied as a lubricant between the heater 109 and the film 106. The heat-resistant grease used in the fixing device 10 of this embodiment mainly contains a base oil that exerts a lubricating function and a thickener that holds the base oil. In this embodiment, the lubricant used is HP-300 grease from Dow Toray Industries, Inc., which uses perfluoropolyether as the base oil and polytetrafluoroethylene (PTFE) as the thickener.

[0031] 5 shows the configuration of the heater holder unit 119, excluding the film 106 and flanges 111R and 111L at both ends from the film unit 101. As shown in FIG. 5, the guide member 107 is a member extending into the internal space of the film 106 in the longitudinal direction of the film, and a recess 107a (see FIG. 4) for accommodating the heater 109 is provided over the entire longitudinal area. The guide member 107 is formed of a heat-resistant resin such as liquid crystal polymer, PPS (polyphenylene sulfide resin), or PEEK (polyether ether ketone). The heater 109 accommodated in the recess 107a of the guide member 107 is fixed to the guide member 107 by fitting one end in the longitudinal direction into a pressing portion provided in the guide member 107 and attaching a power supply connector 117 to the other end.

[0032] Fig. 6 is an image diagram of the flange 111R and the support member 110R before they are attached to the guide member 107. As shown in Fig. 6, the support member 110R attached to the end of the guide member 107 is provided with a claw portion 110e. The support member 110R is attached to the ends of the guide member 107 and the reinforcing stay 112 (the ends in the longitudinal direction of the guide member 107) so as to grip them. Similarly, the support member 110L is attached to the ends of the guide member 107 and the reinforcing stay 112 so as to grip them.

[0033] Next, the process of attaching the flanges 111R and 111L to the heater holder unit 119 will be described.

[0034] First, as shown in Fig. 6, the ears 111a of the flange 111R are inserted into the flange temporary holding portion (through hole) 110b provided in the support member 110R. Next, the support member 110R is inserted into the guide member 107 and the reinforcing stay 112, and then the film 106 is attached so that the end of the film 106 is hooked onto the film guide portion 111g of the flange 111R. Thereafter, the support member 110R and the flange 111R on the opposing surface side are attached in the same manner as above.

[0035] Both sides of the support member 110R are provided with grooves 110d for inserting the support member 110R into the side plate 103R. The same is true for the support member 110L. As shown in Figures 2 and 3, the film unit 101 is attached to the side plates 103R and 103L to which the pressure roller 102 is attached. The pressure roller 102 is attached to U-shaped grooves 103RU and 103LU provided in the side plates 103R and 103L. The film unit 101 is attached to the side plate 103R by inserting the grooves 110d of the support member 110R into the edges of the side plate 103R that form the U-shaped groove 103RU of the side plate 103R. The same is true for the side plate 103L.

[0036] Next, when the heater holder unit 119 is pressed against the pressure roller 102 to form the nip N (the nip during the fixing process), the flange 111R is fixed to the side plate 103R with the screws SC. The same is true for the flange 111L. Therefore, the screws SC correspond to a restricting portion that restricts the movement of the guide member in a first direction perpendicular to the longitudinal direction and away from the roller.

[0037] At this time, a predetermined amount of clearance CR1 (see FIG. 9(a)) is provided between the flanges 111R, 111L and each member of the heater holder unit 119 in the pressure direction of the pressure roller 102. In FIG. 9(a), the clearance between the flange 111R and the reinforcing stay 112 is set to be the clearance CR1. Therefore, even if the flanges 111R, 111L are fixed to the side plates 103R, 103L, the heater holder unit 119 is movable within the range of the clearance CR1.

[0038] Next, the pressure applying structure of the fixing device 10 will be described. Figures 7(a) and 7(b) are side views of the fixing device 10 seen from the side of the side plate 103L, with Figure 7(a) showing the state when pressure is applied and Figure 7(b) showing the state when pressure is released. As shown in Figures 6 and 7(a), one end of the pressure plate 104L is inserted into a hole provided in the side plate 103L and supported, and the other end is pressed by a compression spring 105L to press the upper surface 110c of the support member 110L toward the pressure roller 102. The pressing force received by the support member 110L is transmitted to the reinforcing stay 112 and the guide member 107 shown in Figures 4 to 6, and the heater 109 is pressed toward the pressure roller 102. The same is true for the flange 110R. When the support members 110L and 110R are pressed toward the pressure roller 102, the entire heater holder unit 119 is pressed toward the pressure roller 102.

[0039] At this time, the flanges 111R, 111L are fixed to the side plate 103 with a clearance CR1 between them and the heater holder unit 119, so they are not subjected to the pressing force of the compression springs 105R, 105L. On the other hand, as shown in Fig. 7(b), when the cam 113L lifts the pressure plate 104L to release the pressure, the support member 110L that has been subjected to the pressure from the pressure plate 104L is released from the restraint by the pressure plate 104L. That is, the pressure of the heater holder unit 119 on the pressure roller 102 is released. In this embodiment, the pressure on the pressure roller 102 is released when a jam is processed or the power is turned off.

[0040] As described above, a lubricant is applied between the heater 109 and the film 106. The lubricant is very important for maintaining good lubrication between the heater 109 and the film 106. However, since the film 106 is cylindrical, the lubricant applied to the inner surface of the film 106 may leak out from the end and wrap around to the outer circumferential surface of the film. In particular, if the film 106 does not rotate for a long time with the nip portion N formed after the toner image is fixed, the lubricant that has wrapped around may reach the nip portion N and spread along the longitudinal direction of the nip portion N. If printing is performed in this state, the lubricant may adhere to the recording material P, causing image defects, etc. In addition, the lubricant leaks out from the end of the film 106, and the grease on the inner surface of the film 106 also gradually decreases. Considering the long-term decrease in the lubricant, it is possible to increase the amount of lubricant applied at the beginning of use of the printer 100, but applying more lubricant than necessary increases the risk of the lubricant leaking out from the end of the film 106.

[0041] Therefore, in this embodiment, the inner surface of the film 106 and the heater 109 in the longitudinal direction of the film are actively separated, thereby preventing the lubricant from reaching the end face of the film 106 due to capillary action caused by contact between the inner surface of the film 106 and the heater 109.

[0042] (Film separation mechanism) The film separation mechanism and its operation will be described. Figures 8(a) and 8(b) are views of a part of the side plate 103R side of the fixing device 10 as viewed from the downstream side in the conveying direction of the recording material P, and are diagrams showing the positional relationship of each part in the longitudinal direction of the film. Figure 8(a) shows the state when pressure is applied, and Figure 8(b) shows the state when pressure is released.

[0043] As shown in Fig. 8(a), the overall length of the film 106 is longer than the rubber part 102a of the pressure roller 102, and the flange 111R supporting the film 106 is located outside the rubber part 102a of the pressure roller 102 in the longitudinal direction of the film. Fig. 9(a) is a cross-sectional view taken along dashed line A in Fig. 8(a), and Fig. 9(b) is a cross-sectional view taken along dashed line A in Fig. 8(b), each of which is a cross-sectional view taken from the center of the pressure roller 102 in the longitudinal direction toward the end. Since the rubber part 102a of the pressure roller 102 does not exist on the cross sections in Figs. 9(a) and 9(b), the outline of the rubber part 102a of the pressure roller is projected as a dashed line in Figs. 9(a) and 9(b).

[0044] First, as shown in FIG. 8(a) and FIG. 9(a), in the pressurized state, the rubber portion 102a of the pressure roller 102 is crushed by the pressure, and a nip portion N is formed between the pressure roller 102 and the heater 109 via the film 106. The contour of the film guide portion 111g of the flange 111R is designed so that the film 106 rotates smoothly when pressure is applied (during the fixing process). Therefore, as shown in the area LV1 of FIG. 8(a), the shape of the area of ​​the film 106 that is sandwiched between the pressure roller 102 and the heater 109 and the area that is not sandwiched are almost the same. In other words, in the film longitudinal direction, the area of ​​the film 106 that is not sandwiched between the pressure roller 102 and the heater 109 is also in contact with the heater 109. In particular, if the state of FIG. 8(a) occurs when the film 106 is not rotating, the lubricant is likely to leak out from the film end due to the capillary phenomenon.

[0045] 8(b) and 9(b), when pressure is released, the pressure from pressure plate 104R is released, and the deformation of the elastic layer of rubber part 102a of pressure roller 102 that was crushed by the pressure returns to its original state. Then, heater holder unit 119 that was pressed toward pressure roller 102 is pressed by rubber part 102a and moves in the opposite direction to the pressure direction. With this movement, the part of film 106 pressed by pressure roller 102 also moves.

[0046] In contrast, because flange 111R is fixed to side plate 103R with screws SC, its position does not change even when pressure is released. Therefore, the end of film 106, whose inner surface is supported by guide portion 111g of flange 111R, is restricted by guide portion 111g of flange 111, and maintains substantially the same position as when pressure was applied. The state of film 106 at this time is shown in Figures 8(b) and 9(b). As shown in area LV2 in Figure 8(b), film 106 is deformed, and a space GA is generated between film 106 and heater 109.

[0047] As shown in Fig. 9(b), the position of the end of film 106 on the pressure roller 102 side is regulated by film guide portion 111g of fixed flange 111R, while heater 109 becomes one with heater holder unit 119 when pressure is released and moves in the opposite direction to the pressure application direction. At this time, clearance CR2 is smaller than clearance CR1. The same is true for flange 111L. The inner surface of the end of film 106, which is regulated by guide portion 111g of flange 111R, moves away from the opposing sliding surface of heater 109. Clearance CR3 between heater 109 and the inner surface of film 106 has a relationship of CR1-CR2.

[0048] In this embodiment, the inner surface of the film 106 is separated from the heater 109 in conjunction with the release of pressure, and is performed during jam processing or when the power is turned off, but the timing of pressure release is not limited to these. It is possible to separate the inner surface of the film from the heater 109 by releasing the pressure at any timing when the recording material P is not passing through.

[0049] In this manner, in this embodiment, by separating the inner surface of the film from the heater when paper is not passing through, it is possible to prevent the lubricant from leaking out from the end of the film to the outer peripheral surface due to capillary action caused by contact between the inner surface of the film and heater 109.

[0050] As described above, the fixing device of the first embodiment has a screw SC that restricts the movement of the guide portion 111g in a first direction perpendicular to the longitudinal direction and away from the pressure roller 102. The heater 109, which is a nip portion forming member, is provided so as to be movable in the first direction. When the heater 109 moves from a first position when fixing a toner image to a second position in the first direction, the screw SC restricts the movement of the guide portion 111g in the first direction. This changes the relative position in the first direction between the inner surface of the film 106 and the area of ​​the heater 109 facing the inner surface of the film 106. The fixing device 10 also has side plates 103R and 103L that are part of a frame that holds the pressure roller 102 and the guide portion 111g, and the screw SC fixes the guide portion 111g to the side plates 103R and 103L, thereby restricting the movement of the guide portion 111g.

[0051] Here, the fixing device 10 in this embodiment has a heater 109 in the internal space of the film 106, and the heater 109 and the pressure roller 102 form a nip portion N via the film 106. The material of the heater substrate is not limited to ceramic and may be, for example, metal. Furthermore, the object that sandwiches the film together with the pressure roller is not limited to a heater, and the film separation mechanism of this embodiment can also be applied to a device that is simply a plate without a heat generating function. For example, this may be a fixing device in which the film itself generates heat, a fixing device that has a heat source on the pressure roller side, or a fixing device in which a heater disposed in the internal space of the film is not involved in nip formation.

[0052] Example 2 Example 2 will be described with reference to Figures 10 to 15. The fixing device of this example differs from Example 1 mainly in the configuration of the film unit and the presence or absence of a pressure releasing means, but the basic configuration regarding fixing of the recording material is the same, and therefore a description of the configuration common to Example 1 will be omitted.

[0053] 10 is a perspective view of fixing device 20 of Example 2. Fixing device 20 is significantly different from fixing device 10 in that flange 211R, which supports the end of film 206 from the inside, is movable in the pressure direction of pressure roller 202 and includes flange push-down cam 220R, which pushes down flange 211R. The shape of flange 211R will be described later.

[0054] The flange push-down cam 220R is attached to a shaft rotatably attached to a top plate (not shown) that is provided to connect the left and right side plates 203L and 203R. The cam 220R rotates by a driving force from a driving source (not shown). Unlike the fixing device 10, the fixing device 20 does not have a pressure release means for the pressure plate 204, and the heater holder unit 219 is constantly pressed against the pressure roller 202.

[0055] Fig. 11 is a perspective view of the film indicated by a dashed line. Fig. 12 is a view of a part of the side plate 203R side of the fixing device 20 seen from the downstream side in the conveying direction of the recording material P, and shows the positional relationship of each part in the longitudinal direction of the pressure roller 202. Fig. 12(a) shows the state during normal rotation (during fixing processing), and Fig. 12(b) shows the state in which the flange 211R is pressed down by the flange press-down cam 220R when no paper is passing. Fig. 13(a) is a cross-sectional view taken along dashed line A in Fig. 12(a), and Fig. 13(b) is a cross-sectional view taken along dashed line A in Fig. 12(b), each of which is a cross-sectional view taken from the center of the pressure roller 202 in the longitudinal direction toward the end.

[0056] The position of the flange 111 in the fixing device 10 of the first embodiment is determined by fixing it to the side plate 103 with a screw. As shown in Fig. 13(a), the flange 211R of this embodiment is pressed toward the support member 210R by a compression spring 222R installed between the guide member 207 (having the same shape as the guide member 107 described in the first embodiment) and the flange 211R during normal rotation (during fixing processing). As a result, the abutment portion 211a abuts against the regulation portion 210a of the support member 210R, and the position of the abutment direction is determined.

[0057] Meanwhile, the positioning of the flange 211R in the conveying direction (arrow B direction) of the recording material P is determined by fitting the side surfaces 211b, 211c of the flange 211R between the side surfaces 212b, 212c of the reinforcement stay 212. The flange 211R moves along the side surfaces 212b, 212c of the reinforcement stay 212 in conjunction with the push-down cam 220R. Here, in this embodiment, the flange 211 moves along the reinforcement stay 212, but the configuration is not limited to this as long as the flange 211 is movable toward the pressure roller 202. For example, the flange 211 may be movable along a rail or the like provided on a guide member.

[0058] When push-down cam 220R rotates when no paper is passing through, flange 211R compresses compression spring 222R and is pushed down toward pressure roller 202, as shown in Figures 12(b) and 13(b). Flange 211R, which has been supporting film 206 from its inner surface, pushes down the longitudinal end of film 206, as shown in Figures 12(b) and 13(b). At this time, the position of heater holder unit 219 does not change, so the inner circumferential surface of film 206 and heater 209 can be separated. The flange 211L side also moves in the same way.

[0059] Needless to say, a clearance is provided in advance in the pressing direction so that the flange 211R does not interfere with the heater holder unit 219 when the flange 211R is pressed, so that the flange 211R can move a predetermined amount toward the pressure roller 202. In this configuration, when the flange 211R is pressed down by the push-down cam 220R, the pressure force received by the compression spring 222R is received by the pressure roller 202 via the guide member 207 and the heater 209. Therefore, in order to reliably separate the film 206 from the heater 209, the amount of deformation of the pressure roller 202 due to the pressure from the push-down cam 220R must be smaller than the amount of movement of the inner surface of the longitudinal end of the film 206 due to the downward pressing of the flange 211R. The spring constant of the compression spring 222R must be selected to satisfy such a relationship. The amount by which pressure roller 202 is deformed by the pressing force from push-down cam 220R corresponds to the amount by which heater 209, which is in contact with pressure roller 202 via film 206, moves. The amount by which flange 211R is pushed down is set to about 1 to 3 mm. To prevent oil from seeping out due to capillary action, it is sufficient for film 206 and heater 209 to be spaced apart, and there is no need to space them apart more than necessary. With such a small amount of space, film 206 will not be damaged by excessive load even if it is deformed in the longitudinal direction.

[0060] As described above, in the second embodiment, the flanges 211R and 211L that support the film 206 from the inner surface are pressed down by the pressure cams 220R and 220L, so that the film 206 and the heater 209 can be separated from each other. In the first embodiment, the separation amount between the film 106 and the heater 109 could not be secured to be greater than the amount by which the rubber part 102a of the pressure roller 102 restores its original shape when the pressure is released from the state in which it is deformed by pressure. In contrast, in the present embodiment, the separation amount between the film and the heater can be adjusted by setting the movement amount of the flanges 211R and 211L, that is, the amount of pressing down by the press-down cams 220R and 220L. Therefore, a larger separation amount can be secured, and the inner surface of the longitudinal end of the film can be easily separated from the heater.

[0061] Example 3 Example 3 will be described. The basic configuration of the fixing device 30 of this Example 3 is similar to that of Examples 1 and 2, and a description of the common configuration will be omitted. Fig. 14 is a perspective view of the fixing device 30, and Fig. 15 is a diagram showing a state in which the push-down cam is pushing down the flange, as in Example 2. The fixing device 30 differs from the fixing device 20 in the position of the compression spring that presses the flange against the support member and the shape of the flange, and the other configurations are similar.

[0062] 15, unlike in Example 2, compression spring 322 is provided between top plate 321 and flange 311, rather than between flange 311 and guide member 307. As a result, when flange 311 is pressed down by push-down cam 320, top plate 321 receives the pressing force of compression spring 322. Therefore, it is possible to separate the film from the heater without applying a load to the heater unit and pressure roller via the compression spring. Therefore, the spring constant of the compression spring can be selected without worrying about deformation of the pressure roller.

[0063] Here, the position of the flange 311 in the pressure direction is determined by the abutment portion 311a of the flange 311 abutting against the regulating portion 310a of the support member 310, as in the second embodiment. In this embodiment, as described above, the compression spring 322 can be made stronger without worrying about the load or deformation on the pressure roller. Therefore, the force of the flange 311 abutting against the regulating portion 310a can be increased, and the position of the flange 311 can be more stable. However, the pressing force of the compression spring 322 against the flange 311 needs to be sufficiently small compared to the pressing force of the pressure spring 305 so as not to affect the nip pressure between the heater 309 and the pressure roller 302 during fixing. Note that the positioning of the flange 311 in the conveying direction (arrow B direction) of the recording material P is performed by the side surfaces 311b and 311c of the flange 311 fitting into the side surfaces of the reinforcing stay 312, as in the second embodiment. The flange 313 moves along the side surface of the reinforcing stay 212 in conjunction with the push-down cam 320.

[0064] Also, as another configuration of this embodiment, the configuration shown in FIG. 16 can be adopted. The shape of the flange and the concept of positioning are different between this embodiment and the configuration shown in FIG. 16. The position of the flange 311-2R in the pressure direction shown in FIG. 16 is determined by the abutment portion 311-2a abutting against the top plate 321, not the support member 310R. The same is true for the flange 311-2L. Here, the positioning of the flanges 211, 311, which are the flanges of the second and third embodiments, in the conveying direction of the recording material P is determined by the flanges 211, 311 fitting into both side surfaces of the reinforcing stays 212, 312, as described above. In contrast, a clearance is provided between the side surfaces 311-2b, 311-2c of the flange 311-2 and the side surfaces 312b, 312c of the reinforcing stay. This allows the flange 311 to move by the clearance in the conveying direction of the recording material P relative to the heater holder unit 319.

[0065] Furthermore, a compression spring (not shown) is provided between the flange 311-2 and the support member 310, and by pressing the flange 311-2 toward the center in the longitudinal direction of the film 306, the flange 311-2 hits the end of the film 306, thereby stabilizing the position of the flange 311-2. With this configuration, for example, even in a configuration in which the alignment of the film 306 is adjusted by intentionally shifting the position of the flange 311-2 in the conveying direction of the recording material P, it is possible to achieve both alignment adjustment and spacing between the film 306 and the heater 309 when no paper is passing through. [Explanation of symbols]

[0066] 10, 20, 30 Fixing device 101, 201, 301 film units 102, 202, 302 Pressure roller 106, 206, 306 Film 107, 207, 307 Guide parts 109, 209, 309 Heater

Claims

1. A cylindrical film; a nip portion forming member that contacts an inner surface of the film along a longitudinal direction of the film; a roller in contact with an outer peripheral surface of the film and forming a nip portion together with the nip portion forming member via the film; a guide member disposed opposite an inner surface of an end region of the film in the longitudinal direction and configured to guide the rotation of the film; a fixing device for fixing a toner image formed on a recording material while nipping and conveying the recording material on which the toner image has been formed at the nip portion, a restricting portion that restricts movement of the guide member in a first direction perpendicular to the longitudinal direction and away from the roller, the nip portion forming member is provided so as to be movable in the first direction, A fixing device characterized in that when the nip portion forming member moves in the first direction from a first position when fixing a toner image to a second position, the regulating portion regulates the movement of the guide member in the first direction, thereby changing the relative position in the first direction between the inner surface of the film and the area of ​​the nip portion forming member facing the inner surface.

2. the fixing device has a frame for holding the roller and the guide member, 2. The fixing device according to claim 1, wherein the regulating portion regulates the movement of the guide member by fixing the guide member to the frame.

3. 3. The fixing device according to claim 1, wherein the nip portion forming member is a heater.

Images