JP2010079078A - Fixing device, and image forming apparatus provided with the same - Google Patents

Abstract

A fixing belt end portion is prevented from being damaged, durability is improved, and stable fixing performance is obtained over time.
A fixing device 15A includes a fixing belt 15d that circulates around a fixing roller 15b and a heating roller 15a. The fixing roller 15b is provided with a regulating member 15e that regulates meandering of the fixing belt 15d at both ends in a direction parallel to the axis of the fixing roller 15b. The fixing belt 15d includes an end region 15h including an edge of the belt and a non-end region 15i which is a region other than the end region. While the heating roller 15a and the non-end region 15i are in contact with each other, a gap G is formed between the heating roller 15a and the end region 15h.
[Selection] Figure 3

Description

  The present invention relates to a fixing device used in an electrophotographic image forming apparatus and an image forming apparatus having the same.

  Generally, as a fixing device used in an electrophotographic image forming apparatus such as a copying machine, a printer, a multi-function machine, and a facsimile, a roller pair including a fixing roller and a pressure roller that are in pressure contact, a fixing roller, A thing (heating roller fixing system) provided with a heating means comprising a halogen heater or the like disposed in both or one of the pressure rollers is often used.

  In such a fixing device, after the roller pair is heated to a predetermined temperature (fixing temperature) by the heating means, the recording paper on which the unfixed toner image is formed is pressed against the pressure contact portion (fixing) between the pressure roller and the fixing roller. When the toner passes through the nip portion, the toner image is fixed on the recording paper by the heat and pressure acting on the pressure contact portion.

  Further, a fixing roller (elastic roller) having an elastic layer may be used as the fixing roller. When an elastic roller is used, the roller surface is elastically deformed corresponding to the unevenness of the unfixed toner image, so that the toner image surface comes into contact with the roller surface. Therefore, heat can be effectively transmitted even to an unfixed image with a large amount of toner, and good thermal pressure fixing can be performed. Note that a color image has a larger amount of toner than a monochrome image, and the fixing device for color images preferably includes a fixing roller having an elastic layer.

  Further, in a fixing device including a fixing roller having an elastic layer, the releasability of the elastic layer that is distorted at the fixing nip portion can improve the releasability of the color toner that is more likely to be offset than monochrome. . In addition, in a fixing device including a fixing roller having an elastic layer, the nip shape of the fixing nip portion is convex toward the fixing roller (so-called reverse nip shape), so that the paper peeling performance is improved and the peeling is improved. Paper can be peeled off (self-striping is possible) without using a peeling means such as a nail, and image defects caused by the peeling means can be eliminated.

  However, in a fixing roller having an elastic layer, the thermal conductivity of the elastic layer is very poor. Therefore, when a heating means is provided inside the fixing roller, there arises a problem that the heat transfer efficiency is lowered and the warm-up time is prolonged. Also, if the heat transfer efficiency of the fixing roller is low, there is a problem that it becomes difficult to supply necessary and sufficient heat from the fixing roller to the paper when the process speed of the image forming process is increased (fixing roller). The problem arises in that the heat followability of the is reduced.

  In order to solve such a problem, there has been proposed an external heating fixing type fixing device in which a heating unit is brought into contact with the surface of the fixing roller and the surface of the fixing roller is heated from the outside. Particularly in recent years, there has been proposed a belt heating and fixing type fixing device that uses an endless belt as a heating means and abuts the endless belt heated to a temperature higher than the surface temperature of the fixing roller against the surface of the fixing roller.

As a fixing device of the above-described belt heat fixing method, for example, in Patent Document 1, a heat insulating region having a concave shape is provided in a non-heated region of a heating roller, and heat flows out to the outside through a bearing portion at the end of the heating roller. There has been proposed one that reduces the temperature drop due to.
JP 2006-84647 A (FIGS. 3 and 4)

  However, such a belt heating fixing type fixing device of Patent Document 1 has the following problems.

  In the configuration of Patent Document 1, although the effect of reducing the temperature drop at the end of the heating roller is exhibited, a large amount of heat is applied to the end of the belt member. Here, the end portion of the belt member is a portion that is very loaded because it frequently contacts or rubs with a regulating member (a member that regulates the deviation of the belt) formed on the roller. If a large amount of heat is applied to this part, the belt material will be softened and the buckling strength will decrease. As a result, the belt member is likely to meander (close to the heating roller axial direction), and as a result, the belt member rides on the regulating member, and in the worst case, the belt end is damaged. .

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide a fixing device capable of preventing damage to a belt end and improving durability and obtaining stable fixing performance over time. That is.

  In order to solve the above problems, a fixing device according to the present invention includes a plurality of support members, a fixing belt that circulates around the plurality of support members, and a plurality of support members via the fixing belt. And a pressure member that presses at least one of the support members. Among the plurality of support members, at least one of the support members is a roller for rotating the fixing belt, and at least one support member. The member is a heating member that heats the fixing belt, and at least one support member is provided with a regulating member that restricts meandering of the fixing belt at both ends in a direction parallel to the axis of the roller. The heating unit is configured so that heat from the heating member is less likely to be transmitted in the end region including the end in the parallel direction than in the non-end region other than the end region. It is characterized by There are formed.

  With the above configuration, since the temperature rise at the fixing belt end is reduced, it is possible to suppress a decrease in buckling strength due to thermal degradation or hardness change at the end of the fixing belt. Therefore, it is possible to suppress the fixing belt from moving in the direction of the axis (meandering), and accordingly, it is possible to suppress the adverse effect of the fixing belt riding on the regulating member and the adverse effect of the end crack of the fixing belt. Therefore, according to the configuration of the present invention, the end of the belt can be prevented from being damaged, the durability can be improved, and stable fixing performance can be obtained over time.

  The fixing device according to the present invention is characterized in that, in addition to the above configuration, the heating member and the non-end region are in contact with each other, and a gap is formed between the heating member and the end region. To do.

  According to the above configuration, since a gap is formed between the fixing belt end and the heating member, the amount of heat conducted from the heating member to the fixing belt end can be suppressed.

  In the fixing device according to the present invention, in addition to the above configuration, the heating member is a heating roller, and the heating roller includes a first portion that contacts the non-end region and the end portion through the gap. And a second portion facing the region, wherein the diameter of the second portion is shorter than the diameter of the first portion.

  According to the above configuration, a gap can be formed between the fixing belt end portion and the heating member by providing a difference between the diameter of the first portion and the diameter of the second portion. In addition, complicated processing is not required to create a roller having a difference between the diameter of the first portion and the diameter of the second portion. That is, it is possible to realize a configuration in which a gap is formed between the end portion of the fixing belt and the heating member so that heat from the heating member is less transmitted in the end region of the fixing belt than in the non-end region. .

  In addition to the above configuration, the fixing device according to the present invention is characterized in that the surface of the heating member is coated with a fluororesin.

  With the above configuration, since the friction between the fixing belt and the heating member is reduced, deterioration of the end portion of the fixing belt can be further suppressed. Therefore, the effects of suppressing the meandering of the fixing belt and improving the durability of the fixing belt become clearer.

  In the fixing device according to the present invention, in addition to the above configuration, the pressure member includes a main body that presses the support member via the fixing belt. The regulating member is provided, and the regulating member has a projecting portion projecting to the main body side with respect to a pressure contact surface between the main body and the fixing belt, and an end portion of the main body in the parallel direction. It is characterized in that the protrusion is in contact.

  With the above configuration, the fixing belt can be prevented from riding on the regulating member, and the durability of the fixing belt can be further improved.

  In the fixing device according to the present invention, in addition to the above configuration, the regulating member may be provided on a support member other than the heating member. In addition to the above configuration, the fixing device according to the present invention may have a configuration in which the pressure member presses a support member other than the heating member via the fixing belt.

  The fixing device may be mounted on the image forming apparatus. With the above configuration, since the durability of the belt can be ensured, it is possible to provide stable toner image fixing performance over time.

  A combination of a configuration described in a certain claim and a configuration described in another claim is limited to a combination of the configuration described in the claim cited in the claim. However, as long as the object of the present invention can be achieved, combinations with configurations described in the claims not cited in the focused claims are possible.

  In the fixing device according to the present invention, as described above, a restriction member that restricts meandering of the fixing belt is provided on at least one of the plurality of support members on which the fixing belt is suspended, and the fixing belt is attached to the fixing belt. The heating member is formed so that heat from the heating member is less likely to be transmitted in the end region including the end in the direction parallel to the rotating roller than in the non-end region other than the end region. It is characterized by being.

  Therefore, the temperature rise at the fixing belt end can be reduced, the buckling strength can be prevented from lowering due to thermal deterioration and hardness change at the fixing belt end, It is possible to suppress the end cracking, and the durability of the fixing belt can be improved.

[Embodiment 1]
An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a schematic configuration diagram of an image forming apparatus (color multifunction peripheral). As shown in FIG. 1, the image forming apparatus 100 includes an optical system unit E, four sets of visible image forming units pa, pb, pc, pd, an intermediate transfer belt 11, a secondary transfer unit 14, a fixing device 15A, an internal A paper feed unit 16 and a manual paper feed unit 17 are provided.

  As a representative example of the four sets of visible image forming units pa, pb, pc, and pd, the visible image forming unit pa will be described. The visible image forming unit pa has a configuration in which a charging unit 103a, a developing unit 102a, and a cleaning unit 104a are arranged around a photosensitive member 101a serving as a toner image carrier. The other three sets of visible image forming units pb, pc, and pd have the same configuration as the visible image forming unit pa, and the description thereof is omitted here. The developing units 102a, 102b, 102c, and 102d of the visible image forming units pa, pb, pc, and pd accommodate toners of black (B), cyan (C), magenta (M), and yellow (Y), respectively. Has been.

  An intermediate transfer belt 11 disposed above the photosensitive members 101a, 101b, 101c, and 101d is stretched between tension rollers 11a and 11b. The intermediate transfer belt 11 is tensioned so as not to be bent by both tension rollers 11a and 11b. The primary transfer units 13a, 13b, 13c, and 13d are in pressure contact with the photoreceptors 101a, 101b, 101c, and 101d through the intermediate transfer belt 11, respectively. The secondary transfer unit 14 is in pressure contact with the tension roller 11 a via the intermediate transfer belt 11. A cleaning blade 12 a disposed on a waste toner box 12 that collects toner remaining on the intermediate transfer belt 11 is pressed against the tension roller 11 b via the intermediate transfer belt 11.

  The optical system unit E includes a laser beam source (not shown), a deflector 4 such as a polygon mirror, a folding mirror 8 that guides the deflected beams to four sets of photoconductors 101a, 101b, 101c, and 101d. A beam emitted from a laser beam light source (not shown) is deflected by the deflector 4 in the axial direction (main scanning direction) of the photoconductors 101a, 101b, 101c, and 101d. The deflected beam scans the surfaces of the photoconductors 101a, 101b, 101c, and 101d through the folding mirror 8 and the like.

  The fixing device (fixing unit) 15A is arranged downstream of the secondary transfer unit 14 in the recording paper conveyance path, and mainly includes a heating roller 15a, a fixing roller 15b, a pressure roller 15c, and a fixing belt 15d. Has been. Details of the fixing device 15A will be described later.

  Next, the image forming process will be described. In the visible image forming unit pa, the surface of the photosensitive member (photosensitive drum) 101a is uniformly charged by the charging unit 103a and then laser-exposed by the optical system unit E according to the image information. As a result, an electrostatic latent image is formed on the surface of the photoreceptor 101a. Here, in order to uniformly charge the surface of the photoreceptor 101a while suppressing generation of ozone as much as possible, it is preferable to employ a charging roller type as the charging unit 103a as shown in FIG. Thereafter, the electrostatic latent image on the surface of the photosensitive member 101a is visualized by the toner of the developing unit 102a. Further, the toner image obtained by the visualization is transferred onto the surface of the intermediate transfer belt 11 by the primary transfer unit 13a to which a bias voltage having a polarity opposite to that of the toner is applied.

  The other visible image forming units pb, pc, pd operate in the same manner as the visible image forming unit pa. The toner images formed by the visible image forming units pa, pb, pc, and pd are superimposed on the surface of the intermediate transfer belt 11 in order from the visible image forming unit pd and conveyed to the secondary transfer unit 14. The toner image on the surface of the intermediate transfer belt 11 is fed by the secondary transfer unit 14 to which a bias voltage having a polarity opposite to that of the toner is applied, so that the paper feed roller 16a of the internal paper feed unit 16 or the paper feed roller 17a of the manual paper feed unit 17 is applied. Is transferred to the recording paper fed from the printer. Further, the recording paper on which the toner image is formed is conveyed to the fixing device 15A, and when passing through the fixing device 15A, the toner image is sufficiently heated and pressurized and fused onto the recording paper, and is externally applied by the paper discharge roller 18a. Is discharged.

  Next, the main configuration of the fixing device 15A will be described with reference to FIG. The fixing device 15A fixes an unfixed toner image T formed on the surface of the recording paper P on the recording paper P by heat and pressure. The unfixed toner image T is, for example, a developer such as a non-magnetic one-component developer (non-magnetic toner), a non-magnetic two-component developer (non-magnetic toner and carrier), and a magnetic developer (magnetic toner). It is possible to form with (toner).

  The fixing device 15A mainly includes a fixing roller 15b, a heating roller 15a, an endless fixing belt 15d, a pressure roller 15c, heater lamps 34a and 34b for heating the heating roller 15a, and a pressure roller 15c. The heater lamp 34c for heating, the thermistor 35a for detecting the surface temperature of the fixing belt 15d, and the thermistor 35b for detecting the surface temperature of the pressure roller 15c are configured. The fixing belt 15d is hung on a heating roller (heating member) 15a and a fixing roller 15b which are support members. The pressure roller (pressure member) 15c is pressed against the fixing roller 15b via a fixing belt 15d by a pressure unit (not shown).

  Here, a pressure spring is used as an example of the pressure means. The pressure spring presses the pressure roller 15c toward the fixing roller 15b with a predetermined load (for example, 216N in the present embodiment), and the fixing nip portion (the fixing belt 15d and the pressure roller 15c are mutually connected). The abutting portion N is formed. In this embodiment, the nip width (the length of the fixing nip portion N in the recording sheet conveyance direction) is 7 mm.

  The toner image T is fixed to the recording paper P by passing the recording paper P on which the unfixed toner image T is formed through the fixing nip N. When the recording paper P passes through the fixing nip N, the fixing belt 15d abuts on the toner image forming surface of the recording paper P, while the pressure roller 15c is on the surface of the recording paper P opposite to the toner image forming surface. It comes to contact.

  The fixing roller 15b is rotated in the direction of arrow X in FIG. 2 by a driving mechanism (not shown). The fixing belt 15d is conveyed in the arrow W direction by the rotation of the fixing roller 15b. The heating roller 15a and the pressure roller 15c are rotated along the fixing belt 15d, and rotate in the directions indicated by the arrows V and Z, respectively. By the conveyance of the fixing belt 15d in the direction of arrow W, the recording paper P is conveyed in the direction of arrow Y at the fixing nip N.

  Heater lamps (a halogen lamp as an example) 34a and 34b for heating the heating roller 15a are disposed in a hollow portion on the inner peripheral side of the cylindrical heating roller 15a. The heater lamps 34a and 34b emit light by power supplied from a power supply circuit (not shown) controlled by a control circuit (not shown), and emit infrared rays. Thereby, the inner peripheral surface of the heating roller 15a is heated by absorbing infrared rays, and the entire heating roller 15a is heated. The heat of the heating roller 15a is transmitted to the fixing belt 15d. When the fixing belt 15d is conveyed in the direction of arrow W by the rotational driving of the fixing roller 15b in the direction of arrow X, the heat transmitted from the heating roller 15a to the fixing belt 15d is carried to the fixing nip portion N. In the present embodiment, lamps with rated power of 700 W and 500 W are used as the heater lamps 34 a and 34 b on the inner periphery of the heating roller 15 a, respectively.

  The control circuit performs energization control to the heater lamps 34a and 34b based on the surface temperature of the fixing belt 15d detected by the thermistor 35a. By this energization control, the surface temperature of the fixing belt 15d is maintained within a predetermined range.

  A heater lamp (for example, a halogen lamp) 34c for heating the pressure roller 15c is disposed in a hollow portion on the inner peripheral side of the cylindrical pressure roller 15c. The heater lamp 34c emits light by using power supplied from a power supply circuit (not shown) controlled by a control circuit (not shown), and emits infrared rays. Thereby, the inner peripheral surface of the pressure roller 15c is heated by absorbing infrared rays, and the entire pressure roller 15c is heated. In the present embodiment, a lamp having a rated power of 400 W is used as the heater lamp 34c in the inner peripheral portion of the pressure roller 15c.

  The control circuit performs energization control to the heater lamp 34c based on the surface temperature of the pressure roller 15c detected by the thermistor 35b. By this energization control, the surface temperature of the pressure roller 15c is maintained within a predetermined range.

  FIG. 3 shows the arrangement of the fixing belt 15d, the heating roller 15a, the fixing roller 15b, and the pressure roller 15c.

  As the fixing roller 15b, for example, a two-layer structure in which a core metal and an elastic layer are formed in order from the inside can be used. For the core metal, for example, a metal such as iron, stainless steel, aluminum, copper, or an alloy thereof is used. For the elastic layer, a heat-resistant rubber material such as silicon rubber or fluorine rubber is suitable. In the present embodiment, the diameter of the fixing roller 15b is 30 mm. The core of the fixing roller 15b is iron having a diameter of 20 mm, and the elastic layer of the fixing roller 15b is silicon sponge rubber having a thickness of 5 mm.

  The fixing roller 15b includes a regulating member 15e that comes into contact with an end (edge) of the fixing belt 15d. Normally, in a configuration in which a belt is mounted on a plurality of rollers, the belt is shifted in the axial direction of the roller (meandering) due to the accuracy of the belt or the roller itself or the assembly accuracy of the belt and the roller. Then, a situation occurs in which the belt is detached from the roller. Therefore, in order to suppress this situation, in this embodiment, as shown in FIG. 3, the fixing belt 15d is positioned at a position (limit position) that becomes a limit with respect to the shift in the direction parallel to the axis of the fixing roller 15b. A regulating member 15e is arranged. Thereby, since the fixing belt 15d does not exceed the limit position, the above situation can be prevented.

  As the pressure roller 15c, for example, a three-layer structure in which a metal core, an elastic layer, and a release layer are formed in order from the inside can be used. For the core metal, for example, a metal such as iron, stainless steel, aluminum, copper, or an alloy thereof is used. For the elastic layer, a heat-resistant rubber material such as silicon rubber or fluororubber is used. In addition, a fluororesin such as PFA (a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether) or PTFE (polytetrafluoroethylene) is suitable for the release layer. In the present embodiment, the pressure roller 15c has a diameter of 30 mm (a diameter of a third body portion 15k described later). The core of the pressure roller 15c is iron (STKM) having a diameter of 24 mm and a thickness of 2 mm. The elastic layer of the pressure roller 15c is 3 mm thick silicon solid rubber, and the release layer of the pressure roller 15c. Is a 30 μm thick PFA tube. Further, as shown in FIG. 3, the pressure roller 15c is formed so as to protrude in the roller axial direction from the third body (main body) 15k and a partial region of the end surface of the third body 15k. And a fourth body portion 15j. The diameter of the fourth body part 15j is shorter than the diameter of the third body part 15k. In the pressure roller 15c, the third body 15k is for pressing the fixing belt 15d against the fixing roller 15b, and the fourth body 15j is for supporting the third body 15k.

  As the heating roller 15a, for example, a metal roller having a thickness of about 0.7 to 1.0 mm made of iron or aluminum can be used.

  As the fixing belt 15d, for example, an elastomer material (for example, silicon rubber) excellent in heat resistance and elasticity on the surface of a hollow cylindrical base material made of a heat resistant resin such as polyimide or a metal material such as stainless steel or nickel in order from the inner peripheral side. ) And a three-layer structure in which a release layer made of a synthetic resin material (for example, a fluororesin such as PFA or PTFE) having excellent heat resistance and release properties is formed on the surface. Can be used. Furthermore, when a heat resistant resin such as polyimide is used for the base material, it is more preferable to internally add a fluororesin. By doing so, the friction generated between the fixing belt 15d and the heating roller 15a can be further reduced. In the present embodiment, the fixing belt 15d has a diameter of 50 mm. The base material of the fixing belt 15d is 70 μm thick polyimide, the elastic layer of the fixing belt 15d is 150 μm thick silicone rubber, and the release layer of the fixing belt 15d is a 30 μm thick PFA tube.

  Next, the relationship between the heating roller 15a and the fixing belt 15d will be described in detail. In the present embodiment, as shown in FIG. 3, in the fixing belt 15d, a region including ends (edges) in a direction parallel to the axial direction of the heating roller 15a and the fixing roller 15b is defined as an end region 15h. A region other than the end region 15h is defined as a non-end region 15i.

  The heating roller 15a includes a second body (second portion) 15f facing the end region 15h of the fixing belt 15d and a first body (first portion) 15g facing the non-end region 15i of the fixing belt 15d. And have.

  Further, the diameter of the second barrel 15f of the heating roller 15a is shorter than the diameter of the first barrel 15g, so that the rotation axis of the first barrel 15g and the rotation axis of the second barrel 15f are coaxial. Further, a heating roller 15a is configured. Thereby, in the relationship between the heating roller 15a and the fixing belt 15d, the gap G is formed between the second body 15f and the end region 15h while the first body 15g and the non-end region 15i are in contact with each other. (That is, the end region 15h of the fixing belt 15d and the heating roller 15a are not in contact with each other).

  Therefore, in the fixing belt 15d, the heat from the heating roller 15a is less transmitted in the end region 15h than in the non-end region 15i. Thereby, it is possible to reduce the thermal load on the end region 15h of the fixing belt, and it is possible to suppress the deterioration of the buckling strength due to the thermal deterioration and the hardness change of the end region 15h of the fixing belt 15d. For this reason, it is possible to suppress the fixing belt 15d from riding on the regulating member 15e and the accompanying cracks in the end region 15h.

  In the present embodiment, in order to form a gap G between the end region 15h of the fixing belt 15d and the heating roller 15a, the diameter of the second body 15f is shorter than the diameter of the first body 15g. The heating roller 15a is configured as described above, but such a heating roller 15a can be manufactured without requiring complicated processing. That is, in the present embodiment, the configuration in which the gap G is formed between the end region 15h of the fixing belt 15d and the heating roller 15a is realized without requiring complicated processing.

  Further, the end region 15h of the fixing belt 15d is in contact with a region other than the toner image forming region of the recording paper P in the fixing nip portion N, and is not in contact with the toner image forming region of the recording paper P. Thereby, fixing failure due to insufficient heating of the toner image can be suppressed.

  The configuration on one end side of the fixing device 15A (one end side in the direction parallel to the axial direction of the heating roller 15a) has been described with reference to FIG. Here, although the other end side of the fixing device 15A is not shown in the drawing, the configuration is the same as that of the one end side, and the description thereof is omitted.

  Further, a coating layer made of a fluororesin and having a thickness of 20 to 30 μm is formed on the surface of the heating roller 15a. Thereby, by reducing the friction between the heating roller 15a and the fixing belt 15d, it is possible to secure the durability of the fixing belt 15d and further reduce the axial shifting force.

  As shown in FIG. 4, the regulating member 15e has a protruding portion 15e1 that protrudes toward the pressure roller 15c from the pressure contact surface between the fixing belt 15d and the pressure roller 15c. As shown in FIG. 4, the protruding portion 15e1 is configured to come into contact with the end surface of the third body portion 15k (the end portion in the direction parallel to the axial direction of the fixing roller 15b).

  According to this configuration, since the protruding portion 15e1 of the regulating member 15e and the end surface of the third barrel portion 15k of the pressure roller 15c are in contact with each other, as shown in FIG. 4, the end region 15h of the fixing belt 15d. Is pressed against the fixing roller 15b by the third body 15k of the pressure roller 15c. Therefore, the situation where the fixing belt 15d runs on the regulating member 15e is suppressed, and the durability of the fixing belt 15d can be improved. On the other hand, as shown in FIG. 5, when the projecting portion of the regulating member 15e and the end surface of the third barrel portion 15k of the pressure roller 15c are not in contact, the regulating member 15e and the third barrel of the pressure roller 15c. There is a possibility that the end region 15h of the fixing belt 15d gets over the regulating member 15e in the gap with the end surface of the portion 15k.

  Further, as shown in FIG. 4, it is preferable that the protrusion 15e1 of the restricting member 15e and the end surface of the third body 15k of the pressure roller 15c are brought into contact with each other. However, the protrusion of the restricting member 15e and the pressure roller 15c The applicant conducted an experiment to examine the allowable amount of the gap with the end surface of the third body portion 15k. As a result of this experiment, it was found that the gap between the two was allowed up to 2 mm. More specifically, when the gap is 2 mm or less, the durability performance of the fixing belt 15d can be maintained even when the print processing amount, which is the target number of replacement of the fixing belt 15d, exceeds 300,000 sheets of recording paper. When the gap exceeded 2 mm, the fixing belt 15d was damaged when the number of recording sheets was 100,000 or less.

  In this embodiment, a cylindrical pressure roller 15c is used as a pressure member for forming the fixing nip portion N. However, the pressure member is not limited to a cylindrical shape (roller), and is well known. Any pressure member can be applied to the fixing device 15A of this embodiment. For example, an elastic body (sponge) having a substantially rectangular parallelepiped shape may be used as a pressure member, and one surface of the elastic body may be in contact with the fixing belt 15d. When this elastic body is used as a pressure member, the side surface of the elastic body (the side surface at the end in the direction parallel to the axial direction of the fixing roller 15b) and the protruding portion 15e1 of the regulating member 15e are configured to contact each other. Then, substantially the same effect as the configuration of FIG. 4 can be obtained.

[Embodiment 2]
The following will describe another embodiment of the present invention with reference to FIGS. In the fixing device 15B of the present embodiment, as shown in FIG. 6, a substantially arc-shaped panel member 15a1 is provided as a heating member instead of the heating roller 15a. In addition, since components other than the panel member 15a1 are the same as Embodiment 1, the description is abbreviate | omitted below.

  Heat is generated from the panel member 15a1, and the fixing belt 15d is conveyed while being in contact with the outer peripheral surface of the panel member 15a1. Therefore, heat is transmitted from the panel member 15a1 to the fixing belt 15d.

  FIG. 7A is an example of a cross-sectional view of the panel member 15a1. As shown in FIG. 7A, the panel member 15a1 has a four-layer structure in which a coat layer, a base material, an insulating layer, and a heat generating layer are formed in this order from the side in contact with the fixing belt 15d. The coating layer is a layer having a thickness of about 20 to 30 μm formed by coating and made of a fluororesin or the like, like the coating layer on the surface of the heating roller 15a. As a result, the friction between the panel member 15a1 and the fixing belt 15d can be reduced, the durability of the fixing belt 15d can be ensured, and the shifting force in the direction parallel to the axis of the fixing roller 15b can be further reduced. The base material is made of an inexpensive and strong metal with high thermal conductivity such as aluminum. The insulating layer is provided between the base material and the heat generating layer. By ensuring the insulation between the base material and the heat generating layer, the heating member can be made safe. Note that a planar heating element is formed by the insulating layer and the heating layer.

  Next, a modified example of the panel member 15a1 is shown in FIG. In this example, the panel member 15a1 ′ has a four-layer structure in which a coat layer, a heat generating layer, an insulating layer, and a base material are formed in this order from the side in contact with the fixing belt 15d. As shown in FIGS. 7A and 7B, the heat generating layer can be appropriately formed inside or outside the panel member by changing the method of forming the heat generating layer.

  Next, the relationship between the panel member 15a1 and the fixing belt 15d will be described. In the panel member 15a1, a region facing the end region 15h of the fixing belt 15d is a second body 15f1, and a region facing the non-end region 15i of the fixing belt 15d is a first body 15g1. Here, as shown in FIG. 6, the radius of curvature of the second body portion 15f1 of the panel member 15a1 is shorter than that of the first body portion 15g1.

  The first body 15g1 is shorter than the second body 15f1 in a direction parallel to the axial direction of the fixing roller 15b. Further, the lower surface of the first body portion 15g1 is attached to the upper surface of the second body portion 15f1 so that both ends in the parallel direction are exposed on the upper surface of the second body portion 15f1. Thus, in the relationship between the panel member 15a1 and the fixing belt 15d, the gap G is formed between the second body 15f1 and the end region 15h while the first body 15g1 and the non-end region 15i are in contact with each other. In other words, the end region 15h of the fixing belt 15d and the panel member 15a1 are not in contact with each other. Therefore, even in the configuration using the panel member 15a1 of the present embodiment, the heat from the heating roller 15a is less likely to be transmitted in the end region 15h than in the non-end region 15i in the fixing belt 15d.

[Embodiment 3]
In the first embodiment, the regulating member 15e is provided on the fixing roller 15b side, and the heater lamps 34a and 34b for applying heat to the fixing belt 15d are provided on the supporting member (heating roller 15a) of the fixing belt 15d other than the fixing roller 15b. ing.

  However, the restriction member 15e may be provided not on the fixing roller 15b but on a support member corresponding to the heating roller 15a in FIG.

  In addition, the heater lamps 34a and 34b are not provided with a support member corresponding to the heating roller 15a in FIG. 1, but the heater lamps 34a and 34b may be provided on the fixing roller 15b.

  When the heater lamps 34a and 34b are installed on the fixing roller 15b, the fixing roller 15b functions as a heating member for heating the fixing belt 15d. The fixing roller 15b functioning as a heating member is designed to be in contact with the end region 15h of the fixing belt 15d while being in contact with the non-end region 15i of the fixing belt 15d, similarly to the heating roller 15a of FIG. Is done.

  Furthermore, the heater lamps 34a and 34b and the restricting member 15e may be provided together on one of the rollers 15a and 15b shown in FIG.

[Embodiment 4]
The following will describe another embodiment of the present invention with reference to FIG. In the fixing device of the present embodiment, the heating roller 15a ′ of FIG. 8A is used instead of the heating roller 15a of FIG. Since the components other than the heating roller 15a ′ are the same as those in the first embodiment, the heating roller 15a ′ will be described below, and the description of the other components will be omitted.

  FIG. 8A is a perspective view showing the heating roller 15a ′ of the present embodiment. FIG. 8B is a view showing a cross section of the fixing roller 15d and the vicinity of the end portion in the axial direction of the heating roller 15a of FIG.

  In the first embodiment, the gap G is formed between the end region 15h of the fixing belt 15d and the heating roller 15a. However, as in the following embodiment, the end portion of the fixing belt 15d is formed. The region 15h and the heating roller 15a ′ may be in contact with each other. Hereinafter, the heating roller 15a ′ of this embodiment will be described in detail.

  The heating roller 15a ′ is formed by fitting a heat insulating ring R shown in FIG. 8 into the heating roller 15a of FIG. That is, the heating roller 15a ′ is configured to include the first body portion 15g ′, the second body portion 15f ′, and the heat insulating ring R as shown in FIG.

  The heat insulation ring R is designed so that the outer diameter is the same as the diameter of the first body part 15g ′ and the inner diameter is the same as the diameter of the second body part 15f ′. Further, as shown in FIG. 8, the heat insulation ring R is fitted into the second body portion 15f ′ so that the end surface in the axial direction of the heat insulation ring R and the end surface in the axial direction of the first body portion 15g ′ are in contact with each other. It is.

  In the heating roller 15a ′, the first body 15g ′ and the second body 15f ′ are made of metal such as iron or aluminum, but the heat insulating ring R is formed of the first body 15g ′ and the second body 15f ′. It is formed from a material having a lower thermal conductivity (for example, polyphenylene sulfide resin).

  According to the above configuration, the non-end region 15i of the fixing belt 15d is in contact with the first body 15g ′ of the heating roller 15a ′, while the end region 15h of the fixing belt 15d is the heat insulating ring R of the heating roller 15a ′. Will come into contact. Therefore, even in the configuration in which not only the non-end region 15i but also the end region 15h of the fixing belt 15d is in contact with the heating roller 15a ', the end region 15h is more heated than the non-end region 15i. Heat from 15a 'is difficult to be transmitted.

  In addition, the configuration of one end side (one end side in the axial direction) of the heating roller 15a ′ has been described above with reference to FIG. Here, although the other end side is not illustrated, since it has the same configuration as the one end side, its description is omitted.

  In the present embodiment, the axial length of the first body portion 15g ′, the axial length of the heat insulating ring R on one end side of the heating roller 15a ′, and the other end portion of the heating roller 15a ′. If the total length in the axial direction of the heat insulating ring R on the side is longer than the axial length of the fixing belt 15d, the axial length of the heat insulating ring R can be adjusted as appropriate.

  The fixing device of the present invention is suitable for a copying machine, a multifunction machine, a printer, and a facsimile.

1 is a schematic configuration diagram illustrating a configuration example of an image forming apparatus according to the present invention. 1 is a diagram illustrating a configuration example of a fixing device according to an embodiment of the present invention. FIG. 3 is a diagram illustrating an arrangement of components of a fixing device according to an embodiment of the present invention. It is a figure which shows the relationship between the pressure roller which concerns on one Embodiment of this invention, and a control member. FIG. 10 is an explanatory diagram illustrating a situation where the fixing belt passes over a regulating member. FIG. 6 is a diagram illustrating a configuration example of a fixing device according to another embodiment of the present invention. (A) is the figure which showed the structure of the panel member which is a heating member which concerns on another embodiment of this invention, (b) is the figure which showed the structure of the modification of a panel member. (A) is the perspective view which showed the heating roller with which the fixing device which concerns on another embodiment of this invention is equipped, (b) is sectional drawing of the heating roller and fixing belt of (a).

Explanation of symbols

15A, 15B Fixing device 15a Heating roller (supporting member, heating member)
15a1, 15a1 'Panel member (support member, heating member)
15b Fixing roller (support member)
15c Pressure roller (Pressure member)
15d Fixing belt 15e Restricting member 15e1 Protruding portion 15f Second body (second portion)
15g 1st trunk (first part)
15h End region 15i Non-end region 15k Third body (main body)
100 Image forming apparatus G Gap

Claims (8)

A fixing device comprising: a plurality of support members; a fixing belt that circulates around the plurality of support members; and a pressure member that presses at least one of the plurality of support members via the fixing belt. In
Among the plurality of support members, at least one support member is a roller for rotating the fixing belt, and at least one support member is a heating member that heats the fixing belt. Is provided with a regulating member for regulating the meandering of the fixing belt at both ends in a direction parallel to the axis of the roller,
In the fixing belt, the heating member is formed such that the end region including the end in the parallel direction is less likely to transmit heat from the heating member than the non-end region other than the end region. A fixing device.   The fixing device according to claim 1, wherein the heating member and the non-end region are in contact with each other, and a gap is formed between the heating member and the end region. The heating member is a heating roller;
The heating roller has a first portion that contacts the non-end region, and a second portion that faces the end region via the gap,
The fixing device according to claim 2, wherein a diameter of the second portion is shorter than a diameter of the first portion.   The fixing device according to claim 1, wherein a surface of the heating member is coated with a fluororesin. The pressure member includes a main body that presses the support member via the fixing belt,
The restriction member is provided on the support member pressed against the main body,
The restricting member has a protruding portion that protrudes toward the main body from the pressure contact surface between the main body and the fixing belt,
The fixing device according to claim 1, wherein an end of the main body in the parallel direction and the protrusion are in contact with each other.   The fixing device according to claim 1, wherein the regulating member is provided on a support member other than the heating member.   The fixing device according to claim 1, wherein the pressure member presses a supporting member other than the heating member via the fixing belt.   An image forming apparatus comprising the fixing device according to claim 1.

Images