JPS59127076A - Heat roller fixing device - Google Patents

Abstract

PURPOSE:To improve the rising characteristic of a heat roller and to obtain uniform fixation performance free of temperature unevenness, by providing a pressure and a backup roller which are pressed from the opposite sides against a heat roller consisting of a hollow pipe type mandrel having no shaft part and a positioning member which specifies the position of the heat roller. CONSTITUTION:The mandrel 22 of the heat roller 21 is a hollow pipe type and has no shaft part. The pressure roller 24 is formed by providing a noncohesive elastic material layer 26 of silicone rubber, etc., on the surface of a mandrel 25. The backup roller 27 is positioned on the side opposite to the pressure roller 24 about the heat roller 21 and presses the heat roller 21. Positioning rollers 30 and 30 are arranged facing end parts of the heat roller 21. The heat roller 21 is not supported pivotally, but its position is specified by the positioning rollers and the heat roller 21 is driven while deforming uniformly. The width of a nip part N1 is uniformed entirely and no heat is absorbed from end parts, so the temperature distribution of the heat roller has no unevenness and the uniform fixation performance is obtained.

Description

[Detailed description of the invention] The present invention relates to a device for fixing a toner image on a heated roller.

In general, a developing agent is applied to the electrostatic latent image formed on the charge retaining member to form a toner image, and the toner image is transferred onto recording paper, or the toner image is directly applied with heat or pressure. Image forming means for forming a recorded image by fixing a toner image on a toner image support such as recording paper or a charge holding member by acting on the toner image support have various configurations that have been put to practical use.

The toner that forms the image is usually composed of a thermoplastic resin, carbon black, and other additives, and is used to fix the toner image on a toner image support such as plain paper, electrostatic recording paper, or photosensitive paper. For this purpose, a device called a heat fixing device that applies heat is most commonly used. Heat fixing devices based on various principles have been put into practical use, but those that perform fixing while simultaneously applying heat and pressure have high thermal efficiency, are capable of high-speed fixing, and have excellent paper conveyance. It is the most widely used because of its

FIGS. 1(5) and 1(B) are diagrams showing an example of the configuration of such a conventional heat roller fixing device. In Figure 1 Prisoner, 1
is a pressure roller, and 4 is a heat roller that is in pressure contact with the pressure roller 1. The pressure roller 1 is composed of a core metal 2 and an elastic layer 3 formed on the surface thereof. The elastic body is H
Silicone rubber, called TV silicone rubber, which turns into rubber at high temperatures, or silicone rubber, called RTV, which turns into rubber at room temperature, is used, and during the manufacturing process, it is further impregnated with silicone oil to prevent toner from adhering. This process is often performed. The heat roller 4 has polytetrafluoroethylene, RTV film 1 on the surface of a hollow metal pipe core 5.
It is constructed by providing a heat-resistant non-adhesive layer 6 made of rubber or the like, and a heating lamp 7 such as a Norogen lamp or a far-infrared lamp is installed in the hollow part of the core metal 5. In addition, 8 is a peeling claw that prevents the toner image support such as recording paper from being wrapped around the heat roller, 9 is a blade for removing toner slightly attached to the heat roller 4, and 10 is a holding blade 9. 11 is a temperature sensor for detecting the temperature of the heat roller 4, and 12 is a guide plate for feeding the recording paper that has passed through the fixing roller 1.4.

FIG. 1 (I3) is a sectional view taken along the Y-77 plane of the heat roller fixing device shown in FIG. 1 (5). In this case, the shaft 14 is the core metal 5
or is formed integrally with the core metal 5, and is rotatably held by a bearing 15. Similarly, the end of the pressure roller 1 also has a small diameter portion 13 of the core metal 2, and this small diameter portion 13 is provided with the bearing 1.
It is rotatably supported by 6. The heat roller 4 and the pressure roller 1 are applied with a pressing force of 1 to 2 KSI per unit length (1 cm) of the contact area of both rollers by a pressure means (not shown) via bearings 14, ]5. is added, and as a result, the elastic layer 3 of the pressure roller 1
is deformed to form a nip portion N1. Nip part N1
Usually has a width of about 3 to 10 wn, and particularly in small devices, the width is often about 3 to 5 wn.

Both rollers 1.4 are rotated in the direction of the arrow while being pressed against each other, and the surface of the toner image support body on which the toner image is formed is opposed to the heat roller 4, and the pressure nip portion N1 of both rollers is is allowed to pass.

The heat roller 4 is heated in advance by the heating lamp 7.
The toner image support is heated to about 00C, and when the toner image support passes through the pressure nip N1, the toner is melted and fixed to the support surface.

However, in a heat roller fixing device with such a configuration, it takes one to several minutes to start up the device until the temperature reaches the point where it can be bonded when energized, so it is necessary to always preheat it so that it can be used immediately. It is common practice to leave the product for 10 minutes, but it has the disadvantage that preheating energy is wasted, and without preheating, the inconvenience of long waiting time (rise time) cannot be solved. .

Further, in a fixing device having such a configuration, FIG. 1 (I3
), since the shaft 14 with a large heat capacity is attached to the core metal 5 at the end of the heat roller 4, the temperature drop in this part is significant, which becomes an obstacle to achieving uniform fixing performance. In order to improve this, heat insulating means has been applied to the bearing part, but this has the disadvantage of complicating the device.Furthermore, in the conventional fixing device, the heat roller Since the core bar 5 of No. 4 is formed thick, there is a limit to the heat conduction speed, and when fixing a large number of toner supports in succession, the surface temperature of the heat roller decreases, causing poor fixing. There is a problem.

Among the various drawbacks of these conventional devices, it is conceivable to reduce the thickness of the core metal in order to shorten the rise time of the hot roller, but in this case, the following problems arise. That is, when the thickness of the core bar 5 is made thinner, as shown in FIG. 2 (5), since the shaft 14 is inserted at the end of the heat roller 4, the pressure roller 1 is It is possible to form a wide nip portion N without deforming even when subjected to strong pressure.

However, as shown in FIG. 2(B), the central portion of the heat roller 4 in the longitudinal direction is deformed by the pressure from the pressure roller 1, resulting in an distorted shape. The elastic layer 3 of No. 1 is not pressurized further, and a narrow nip portion N2L is not formed. As a result of the decrease in the width of the nip portion at the central portion of the heat roller 4, the fixing performance in this portion is reduced, causing problems such as uneven fixing and local toner offset.

The present invention was made in order to solve the drawbacks and problems of the conventional heat roller fixing device, and it has a short start-up time, can perform high-speed continuous fixing, and has a uniform temperature distribution. The object of the present invention is to provide a heat roller fixing device having fixing performance.

Next, prior to a detailed explanation of the present invention, the principle of the present invention will be explained.

The present invention consists of a heat roller with a thin core metal and no support shaft, and the heat roller is pinched by a pressure roller and a backup roller, and the pressure sealer and backup roller are rotated. In other words, the heat roller is rotated while being deformed over its entire length. As described above, since the heat roller according to the present invention does not have a shaft and has a uniform thin cross-sectional shape, it is uniformly deformed by pressure and prevents uneven fixing. can. In addition, because the heat capacity is reduced by making the core metal thinner, the start-up time is shortened almost in proportion to the wall thickness.Also, by making the core metal thinner, the heat transfer speed becomes faster, resulting in higher speeds. Continuous fixing performance is improved.

FIGS. 3(5) and 3(B) show a thin-walled pipe with a uniform wall thickness over its entire length, which is used as the core metal of such a thermal roller.

The radius of this thin-walled pipe is r, the length is b, and the wall thickness is 11. When pressure P is applied in the direction of crushing the pipe, the amount of deformation of the pipe in the P direction is δy, and the amount of deformation in the direction perpendicular to this is δy. Assuming δX, these are expressed by the following formula.

However, E is the longitudinal elastic modulus of the applied material, ■ is the cross-sectional quadratic modulus, and I in the pipes shown in FIGS. 3 (5) and (13) is expressed by the following equation.

Z Table 1 (However, the values in Table E It is υ. For reference, the values for phosphor bronze are also listed.

The heat roller of the heat fixing device usually has a temperature of 160°C to 200°C.
20 in Table 1.
The value of E at 4.4 [stainless steel is 1.'86
X] 0' Ky/mi, aluminum is 0.6
7 X 10'Q / +u! ), Table 2 shows the calculated deformation amounts δX and δy of the pipe-shaped core metal when the radius r, wall thickness h, and pressing force P of the core metal are changed.

In the case of stainless steel, the thickness of the core metal practically used in the heat roller of a conventional fixing device is 1.5 or so, which is close to the lower limit when the radius is about 20 mm, and b = 30.
The amount of deformation when pressed against a pressure roller with a force of 50 to 2 against the entire length at 0 tra is an extremely small value of 0.038-. Similarly made of aluminum and 2D
I11 In the case of a cored metal, a cored metal with a thickness of 20 mm or more in radius is used, and as shown in Table 2, the amount of deformation is 0.059.
extremely small.

Table 2 By the way, in order to obtain the same nip width for core metals with the same radius and the same length, when applying a pressure welding force of 50 to 2, the pressure of the core metal is When the wall thickness is reduced, significant deformation of the core metal occurs. For example, when using thick stainless steel, the amount of deformation in the pressure application direction is 1.02 mm, and 0.8 tran
In the case of an aluminum core metal with a wall thickness of , it is 069 m.

Therefore, in the configuration of the heat roller of a conventional fixing device, when a pressure contact force that causes deformation is applied to the heat roller, deformation occurs at the center, but because the shaft member is arranged at the end, There is no deformation, and therefore, the width of the two tabs is non-uniform, resulting in uneven fixing.

On the other hand, in the present invention, the heat roller has a uniform cross-sectional shape over its entire length, and no additional shaft member is attached to the end, so even if deformation occurs, the heat roller is uniformly shaped. A deformed nip portion of non-uniform width is not formed. Therefore, the thickness of the core of the heat roller can be made thinner, and the start-up time of the heat roller after energization can be significantly shortened.

For example, by changing the stainless steel core metal, which was conventionally formed with a wall thickness of 1.5 mm, to a core metal with a wall thickness of 0.5 wn, the startup time of the thermal roller can be reduced to about 1/3. can be shortened to Similarly, if an aluminum core metal with a wall thickness of 08 mm is used instead of an aluminum core metal with a wall thickness of 2 mm, the heat roller can be heated to a predetermined temperature in a rise time of about /2.5.

-Also, since the amount of heat conduction of a solid is inversely proportional to its thickness, by reducing the thickness of the core metal, it is possible to transfer a large amount of heat continuously at a high speed. When fixing is performed, a large amount of heat can be supplied via a heat roller. Therefore, by reducing the thickness of the core metal and using a heated roller, high-speed continuous fixing performance can be improved.

Furthermore, when a thin-walled core metal is used as a heat roller, the core metal is rotated while being elastically deformed, and as a result, the core metal of the heat roller plays the role of an elastic body, and conventionally, the nip is formed. It is possible to omit the spring used in the previous model and obtain the necessary spring action with the core metal. For example, radius 20++++n.

A stainless steel core with a length of 300 rran and a wall thickness of 0.5 mm is deformed by approximately 1 mm in radius.
A repulsion force of approximately 50 to 2 can be generated and Δ.

In addition, if a heat roller is made using a thin core metal and fusing is performed while deforming the heat roller by the action of a pressure roller and a bank-up roller, the temperature of the heat roller at the part that comes into pressure contact with the pressure roller Since the curvature is increased, a wider nip is formed and the fixing action can be increased.

In addition, since the necessary nip width can be secured with a smaller applied pressure, the structure of the frame that supports the pressure roller and backup roller can be simplified.
Furthermore, it is possible to stabilize the running properties of the toner image support and reduce the occurrence of wrinkles.

Next, specific embodiments of the present invention, which have these many advantages, will be described.

FIG. 4(5) is a partially sectional side view of an embodiment of the heat roller fixing device according to the present invention. In the figure, reference numeral 21 denotes a thermal roller, the core metal 22 of which is shaped like a hollow pipe and has a uniform cross-sectional shape over its entire length, and no additional shaft portion is formed at the end.

A non-adhesive layer 23 is formed on the surface of the core bar 22 as in the conventional case.
-It has been done. Reference numeral 24 denotes a pressure roller, which is constructed by providing a non-adhesive elastic layer 26 such as silicone rubber on the surface of a core metal 25. The elastic layer 26 is usually formed with a thickness of about 5 cm, and when silicone rubber is used, it is impregnated with silicone oil during the manufacturing process to increase its non-adhesion. 27 is a backup roller, heat roller-2
The heat roller 21 is arranged to be located on the opposite side of the pressure roller 24 with the heat roller 21 as the center.
It puts pressure on the back amp roller 27
may be made of metal, but in order to prevent heat from being taken away from the heat roller 21, it is preferable to apply heat insulation treatment.

Furthermore, by coating the surface with a slightly flexible material, the surface of the heat roller 2 will not be damaged even if foreign matter adheres to it. Therefore, the backup roller 27 has a heat-resistant, flexible surface layer 29 with poor thermal conductivity on the surface of the core bar 28.
It is preferable that the Suitable materials for the surface layer 29 include silicone rubber used for the pressure roller 24 and heat-resistant materials such as polytetrafluoroethylene processed into a web.

By the way, the heat roller 2] is pipe-shaped with a uniform cross section, has no shaft at the end, and is not particularly supported, so pressure is applied between the pressure roller 24 and the backup roller 27. If it is deformed by being deformed, it will try to escape from the position shown in No. 414 and return to a circular shape. Therefore, in order to hold the heat roller 21 at the illustrated position, it is necessary to arrange a positioning member for the heat roller 21. Figure 4 (
30.30 in A) is the other positioning roller. As shown in FIG. 4 (13), this roller 30, 30 only needs to be placed opposite the end of the heat roller 21, so that its contact area with the heat roller 21 is extremely small. Therefore, it is possible to prevent heat from being taken away from the heat roller 21 and prolonging the start-up time.

FIG. 4(B) is a front view of this embodiment. Figure 4 (
In I3), 31 and 32 are frames constituting the fixing device, 33 is a pressure roller shaft, and 34 is a bearing of the pressure roller shaft 33, which is attached to the frame 31.

35 is the shaft of the backup roller 27, and 36 is attached to the frame 32 by its bearing. 38 is a bearing attached to a shaft 37 that pivotally supports the positioning roller 30 of the heat roller 21. The positioning roller 30 is
It consists of a large diameter part 30' and a small diameter part 30'', and the small diameter part 30'' restricts the movement of the heat roller 21 in the radial direction.
The end face of ' serves to position the heat roller 21 in the thrust direction.

The configuration for applying pressure between the pressure roller 24 and the bank amplifier roller 27 can be the same as the configuration for applying pressure to the pressure roller and the heat roller in a conventional heat roller fixing device. In this example, the 41st old)
As shown in the figure, the frame is divided into upper and lower parts to form a slight gap, and the upper frame 32g backup roller 27 is supported by the lower frame 3 and the pressure roller and positioning roller 30 are supported. The spring member is configured to close the gap between the frames 3 and 32 and apply pressure. both frames 3
As a result of the pressure being applied between 1.32 and 2, the heat roller 21 is protected by pressure roller 24 and backup roller 27, deforms within its elastic limit, is crushed in the direction of pressure, and is compressed perpendicular to this. The shape is expanded in the direction in which it is pushed. The positioning roller 30.30 is the heat roller 21.
is placed at a position corresponding to this deformed state.

In the heat roller fixing device shown in this embodiment, during operation, the pressure roller 24 and the bank amplifier roller 27 are driven while maintaining a pressurized state, and the heat roller 21 is not supported pivotally, but is positioned. At the position regulated by the rollers, it deforms uniformly and then rotates as a result. Therefore, the width of the nip N1 formed between the heat roller 2 and the pressure roller 24 is uniform over the entire length, and heat is not removed from the ends, so the temperature distribution of the heat roller is Uniform fixing performance can be obtained without unevenness.

FIG. 5 (B) is a diagram showing another embodiment of the present invention. One of the differences between this embodiment and the previous embodiment shown in FIGS. 4(5) and 4(B) is the configuration of the thermal roller positioning member. In FIG. 5(B), 39 is a thermal roller positioning member, and this member 39 has an annular groove 41 having a bottom surface 40 formed therein. As can be seen from FIG. 5(B), the end of the heat roller 21 is assembled so as to fit into the groove 41, and the positioning member 39 rotates around the center of the annular groove 41. It is maintained as such.

The outer diameter of the annular groove 41 is approximately equal to or slightly larger than the maximum outer diameter of the heat roller 21 deformed by the pressure from the pressure roller 24 and the bank amplifier roller 27.
The inner diameter of the heat roller 1 is smaller than the minimum inner diameter of the deformed heat roller 21. When the heat roller 21 is deformed within its elastic limit due to the pressure of the pressure roller 24 and the backup roller 27, the diameter in the pressure application direction decreases, and the diameter in the direction perpendicular to this increases; Since the outer diameter portion of the heat roller 21 approaches the outer diameter portion of the groove 41 of the positioning member 39, the heat roller 21 is positioned by the outer diameter portion of the groove 41. Positioning member 3
Since the roller 9 is rotatably held, even if the heat roller 2 is deformed and a portion thereof comes into contact with the positioning member 39, the heat roller 21 can rotate without being subjected to resistance. The pressure roller 24, the positioning member 39, and the backup roller 27 are mounted on bearings 34, 42, and 36, respectively.
By driving one or both of the pressure roller 24 and the backup roller 27, the heat roller 21 can be rotated without any trouble.

5 (43 in Bl is a gear that drives the pressure roller 24.

In this embodiment, the heat roller 21 has an opportunity to come into contact with the positioning member 39 at the end, but the contact area is extremely small, and unlike a conventional heat roller provided with a shaft member, the heat roller 21 is not rolled from the end. It is possible to prevent the occurrence of such an inconvenient phenomenon that the heat of 2- is taken away and temperature unevenness occurs.

Furthermore, in the embodiment shown in FIGS. 5(5) and 5(B), a power transmission means is provided on the rotatably held positioning member, and the pressure roller 24 or the push-up roller 270 turns The pressure roller 24, heat roller 21,
The bank amplifier roller 27 can be rotated smoothly and operated more favorably.

FIG. 6 shows an embodiment configured in this manner. A gear 43 is attached to the shaft 33 of the pressure roller 24, a gear 44 is attached to the positioning member 39, and a gear 45 is attached to the bank up roller 27. Gears 43 and 44 and gears 44 and 45 are meshed with each other, and when any one of the gears is driven, the other gears are also driven. Therefore, in this embodiment, as in the embodiment shown in FIG. 5, the positioning member 39 is driven to rotate when it comes into contact with the heat roller 21, and acts so as not to interfere with the rotation of the heat roller 21. Rather, it is driven to rotate separately from the rotation of the heat roller 21, and when the heat roller 2 comes into contact with the groove 41 of the positioning member 39, it actively rotates it. It is something. However, since the heat roller 2J and the positioning member 39 are not directly connected to each other, the rotation speed of the positioning member 39 only needs to be close to the rotation speed of the heat roller 21; It doesn't have to be. That is, the outer circumferential speed of the annular groove 41 may be approximately equal to the circumferential speed of the heat roller 2 or the backup roller 27. In addition, since the pressure roller 21 and the backup roller 27 are connected through a gear, they do not necessarily need to be driven simultaneously, and either one of them may be configured to be driven to rotate.

In this embodiment, the power transmission between the positioning member 39, the pressure roller 24, and the backup roller 27 is as follows.
Although an example in which gears are used is shown, other means such as a chain or a timing belt may also be used as the power transmission means.

In conventional heat roller fixing devices, the pressure between the pressure roller and the heat roller is obtained by elastic pressure means such as springs,9 which has the disadvantage of complicating the device, but in the present invention, As mentioned earlier, the core metal of the heat roller is a thin one that is deformed under pressure within its elastic limit, so it is necessary to give the heat roller the role of an elastic pressure welding means that was previously required. I can do it. Therefore, in the present invention, the bearings of the pressure roller and the backup roller are fixed at positions where the heat roller is elastically deformed by the pressure of the pressure roller and the backup roller, and a simple heat roller fixing device is established by heating. realizable.

FIG. 7 is a diagram showing the structure of a frame for holding a bearing configured to satisfy the above conditions, where 46 is a lower frame, 47 is an upper frame, and 48 is both frames.
The connecting pin 49 is a screw for fixing both frames 46 and 47. The lower frame 46 supports the pressure roller bearing 34 and the positioning member bearing 42, while the upper frame 47 holds the backup roller bearing 36.

The upper frame 47 can be opened upward using the connecting pin 48 as a fulcrum by removing the screw 49.
When the heat roller 21 is tightened, the heat roller 2 becomes elastically deformed as shown in FIG. It is constructed to be able to obtain pressure.

The thickness of the core metal of the thermal roller in each of the above embodiments is not limited to a specific value, and various values can be applied, but as mentioned earlier, (1), (2) ), (
3) The amount of deformation of the core metal calculated by the formula is 0.1 r
Good effects can be obtained under conditions where tan or higher,
In particular, even better effects can be obtained under conditions where the amount of deformation is 0.25 ran or more. It was thought that it would be completely impossible to apply a heat roller having a core metal with a thick wall under such conditions to conventional equipment. The present invention has various effects, but when seeking one of them, which is the effect of flattening the temperature distribution by preventing heat radiation from the heat roller bearing part, It is also effective to apply the configuration of the present invention to conventional thick-walled thermal rollers.

As described above in detail based on the embodiments, the present invention provides a heat roller fixing device made of a hollow pipe-shaped core metal having a uniform cross-sectional shape over the entire length and having no shaft portion. It is composed of a heat roller, a pressure roller and a backup roller that press against the heat roller on opposite sides, and a positioning member that restricts the heat roller to a predetermined position. can be used, and the rise characteristics of the thermal roller are improved.
Furthermore, uniform fixing performance can be obtained since no temperature unevenness occurs.

Further, by providing a flexible heat insulating layer on the surface of the backup roller, the start-up time of the heat roller fixing device can be further accelerated, and damage to the surface of the heat roller can be prevented.

Furthermore, by using a rotatable member having an annular groove into which the end of the heat roller is inserted as a positioning member, the heat roller using a thin core metal can be smoothly rotated. Furthermore, by rotationally driving the positioning member having such a configuration, even more reliable rotation of the heat roller can be ensured.

Furthermore, by using the elastic repulsive force of the elastically deformed thermal roller as the pressure contact force for forming the nip portion, additional means such as springs for obtaining the pressure contact force can be omitted, and the configuration can be simplified. The effect of this can be obtained.

[Brief explanation of the drawing]

Figures 1 (5) and (B) are a partially sectional side view and a partially sectional front view of a conventional heat roller fixing device, and Figures 2 (A) and (
I3) is a diagram showing the deformed state of the heat roller in the first section, the device shown in (I3), and FIG. 3 (5) is a diagram showing the deformed state of the heat roller in the device shown in FIG. FIG. 3 (13) is a side view of the pipe; FIG. 3 (13) is a perspective view thereof; FIG.
FIG. 5(B) is a partially omitted front view, FIG. 5(5) is a partially sectional side view of another embodiment of the present invention, and FIG. FIG. 6 is a partially sectional front view of still another embodiment of the present invention, and FIG. 7 is a front view of FIG.
FIG. 7 is a diagram showing the configuration of a frame portion applied to Bl or the embodiment shown in FIG. 6; In the figure, 21 is a heat roller, 22 is a metal core, 23 is a non-adhesive layer, 24 is a heating roller, 25 is a metal core, 26 is an elastic layer, 27 is a backup roller, 28 is a metal core, 29
is a heat-resistant flexible surface layer, 30 is a positioning roller, 3],
32 is a hummum, 33 is a pressure roller shaft, 34 is its bearing, 35 is a backup roller shaft, 36 is its bearing, 37 is a positioning roller shaft, 38 is its bearing, 3
9 is a heat roller positioning member, 41 is an annular groove, 42 is a positioning member bearing, 43, 44, 45 is a gear, 46 is a lower frame, and 47 is an upper frame. Patent applicant: Olympus Optical Industry Co., Ltd. Representative Patent Attorney Kenji Mogami (A) Figure 5

Claims (5)

[Claims] (1) In a heat roller fixing device for fixing a toner image formed on a toner image support to the support under the action of heat and pressure, the shaft portion has a uniform cross-sectional shape over the entire length. On the surface of the hollow pipe-shaped core metal that is not equipped with
a heat roller configured by forming a non-adhesive layer; a pressure roller having a non-adhesive elastic layer on a core metal and in pressure contact with the heat roller; A bank up roller that presses against the heat roller;
a positioning member for regulating the heat roller to a predetermined position between the pressure roller and the back amplifier roller; A heat roller fixing device characterized in that it is configured to rotate. (2) The heat roller fixing device according to claim 1, wherein the backup roller is composed of a metal core and a flexible heat insulating layer formed on the surface of the core metal. (3) The positioning member includes an annular groove into which the end of the heat roller is inserted, and the outer diameter of the annular groove is approximately equal to the maximum outer diameter of the heat roller that is deformed by pressure from the pressure roller and the backup roller. or slightly larger, and the inner diameter is smaller than the minimum inner diameter of the heat roller that deforms under pressure, and the bottom surface of the annular groove is arranged so as to approach and oppose the end surface of the heat roller, and the center of the annular groove is the center of rotation. The heat roller fixing device according to claim 1, wherein the heat roller fixing device is rotatably held. (4) The positioning member is configured to rotate at a circumferential speed substantially equal to the circumferential speed of the pressure roller or the backup roller by means of a power transmission means. Heat roller fixation device. (5) The pressure roller and backup roller are
The heat roller fixing device according to the invention, wherein the heat roller is rotatably held at a position where the heat roller is elastically deformed, and the heat roller is fixed by an elastic repulsion force of the deformed heat roller.