JP2000330412A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent unevenness in coating of a release agent. SOLUTION: The device is provided with press roll 120 forming a fixing nip part N between a fixing belt 110 by being brought into a pressurized contact with a back up roll 130 through the fixing belt 110 that is hung between a heating roll 140 and the backup roll 130 and circulated, an auxiliary heating means 123 heating the press roll 120 and a release agent coating means 150 coating the release agent by being abutted to the fixing belt 110 more downstream than the fixing nip part N and more upstream than the heat roll 140 concerning the circulating direction of the fixing belt 110. In this case, the release agent coating means 150 is arranged above the auxiliary heating means 123 and downstream of the fixing nip part N concerning a passing direction of recording material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device used in an image forming apparatus such as a printer, a facsimile, a copying machine, etc., capable of forming a toner image on a recording material such as paper by using an electrophotographic technique. In particular, the present invention relates to a fixing device using a fixing belt.

[0002]

2. Description of the Related Art In general, an image forming apparatus for forming a toner image on a recording material such as paper by using an electrophotographic technique includes a photoconductor which is driven to rotate, and an electrostatic latent image formed on the surface by exposing the photoconductor. Exposure means for forming an image, developing means for developing the electrostatic latent image into a toner image, transfer means for transferring the toner image to a recording material, and a recording material on which the toner image has been transferred by the transfer means And a fixing device for fixing the toner image on the recording material by heating while passing through the recording material.

As a conventional fixing device, a so-called belt fixing type fixing device as shown in FIG. 4 is known (Japanese Patent No. 2813297). This fixing device is provided with a main heating source H1.
An endless fixing belt B which is stretched and circulates between a heating roller R3 and a backup roller R1 and a fixing nip between the fixing belt B and the backup belt R1 which is pressed against the backup roller R1 via the fixing belt B. A pressure roller R2 forming a portion N, an auxiliary heating source H2 as an auxiliary heating means for heating the pressure roller R2, and a heating roller R3 downstream of the fixing nip portion N with respect to the circulation direction of the fixing belt B. And an oil application roller R4 serving as a release agent applying means for applying the release oil by contacting the fixing belt B on the upstream side, and the recording material C on which the toner image is formed.
Is passed through the fixing nip portion N to heat and fuse the toner image to fix the toner image on the recording material C.

[0004]

Generally, since the viscosity of a release agent such as a release oil greatly depends on the temperature, the amount of the release agent applied to the fixing belt varies depending on the temperature of the release agent application means. . In the above-mentioned conventional fixing device (FIG. 4), the oil application roller R4 is located above the auxiliary heating means H2 of the pressure roller R2, but in the direction in which the recording material C passes (the direction from right to left in FIG. 4). ), Since it is arranged upstream (right side in FIG. 4) of the fixing nip portion N, the radiant heat from the auxiliary heating means H2 and the hot air flow are obstructed by the backup roller R1 and the belt B, and the oil application roller It hardly reaches R4. Therefore, the oil application roller R4 is mainly heated only by the belt B. For this reason, the temperature of the oil application roller R4 does not easily rise particularly in the early stage of the operation of the fixing device.

On the other hand, when the recording material C passes through the fixing nip N of the belt B, the temperature of the portion in contact with the recording material C is significantly reduced, so that a remarkable temperature difference occurs in the width direction. Since this temperature difference is also reflected in the temperature of the oil application roller R4, especially in the early stage of operation when the temperature of the oil application roller R4 is not sufficiently increased, the temperature difference in the axial direction of the oil application roller R4 is reduced. As a result, there is a problem that a difference occurs in the amount of oil applied in the axial direction of the oil application roller R4, that is, in the width direction of the belt B, and the fixed image also becomes uneven.

That is, the above-mentioned conventional fixing device (FIG. 4)
However, there is a problem that uneven application of the release agent easily occurs.

An object of the present invention is to solve the above-mentioned problems and to provide a fixing device which is less likely to cause uneven application of a release agent.

[0008]

According to another aspect of the present invention, there is provided a fixing device comprising: an endless fixing belt stretched and circulated between a heating roller and a backup roller; A pressure roller pressed against the backup roller to form a fixing nip portion with the fixing belt, an auxiliary heating unit for heating the pressure roller, and the fixing nip portion with respect to a circulation direction of the fixing belt. A release agent applying means for applying a release agent by contacting the fixing belt on the downstream side of the heating roller and on the upstream side of the heating roller, and the recording material on which the toner image is formed is supplied to the fixing nip portion. A fixing device for fixing the toner image on a recording material by heating and melting the toner image, wherein the release agent applying unit includes:
It is characterized by being disposed above the auxiliary heating means and downstream of the fixing nip in the direction of passage of the recording material. The fixing device according to claim 2,
2. The fixing device according to claim 1, wherein the release agent applying unit holds a release agent to be applied,
A contact portion for applying a release agent in contact with the fixing belt, wherein at least the contact portion is located above the auxiliary heating means, and from the fixing nip portion with respect to a passing direction of the recording material. Is also arranged on the downstream side. The fixing device according to claim 3 is the fixing device according to claim 1 or 2.
In the fixing device described above, the release agent applying unit has a release agent holding unit that holds a release agent to be applied, and a contact unit that contacts the fixing belt and applies the release agent. Wherein at least the release agent holding portion is disposed above the auxiliary heating means and downstream of the fixing nip portion with respect to a direction in which the recording material passes.

[0009]

An endless fixing belt stretched and circulated between a heating roller and a backup roller, and a fixing belt pressed against the backup roller via the fixing belt. The fixing belt heated by the heating roller, and the auxiliary heating unit that heats the fixing roller. When the recording material on which the toner image is formed passes through the fixing nip portion formed by the pressure roller, the toner image is heated and melted and fixed on the recording material. Further, since the image forming apparatus has the release agent applying means for applying the release agent in contact with the fixing belt, the offset phenomenon in which the toner image on the recording material is transferred to the fixing belt hardly occurs. The application unit applies the release agent by contacting the fixing belt on the downstream side of the fixing nip portion and on the upstream side of the heating roller with respect to the circulation direction of the fixing belt, so that the fixing belt heated by the heating roller is applied. Further, a situation in which the temperature is lowered by the application of the release agent before reaching the fixing nip portion is also prevented. According to the fixing device of the first aspect, the release agent applying unit is disposed above the auxiliary heating unit and downstream of the fixing nip with respect to the recording material passing direction. Therefore, the radiant heat from the auxiliary heating means and the hot air flow reach the release agent applying means almost without being hindered by the backup roller and the fixing belt. Therefore, the release agent applying means is directly heated not only by the contact with the fixing belt but also by the radiant heat from the auxiliary heating means and the hot air flow. For this reason, the release agent applying unit is heated relatively quickly in the early stage of the operation of the fixing device, and the temperature is stabilized early.
Therefore, even if the fixing belt in which the temperature difference occurs in the width direction due to the recording material passing through the fixing nip N comes into contact with the release agent applying unit, the temperature difference is not so much reflected on the temperature of the release agent applying unit. Therefore, the temperature difference in the belt width direction of the release agent applying unit is less likely to occur, and as a result, the difference in the amount of the release agent applied in the belt width direction of the release agent applying unit is less likely to occur. The image is less likely to be uneven. As described above, according to the fixing device of the first aspect, an effect is obtained that uneven application of the release agent is less likely to occur. According to the fixing device of the second aspect,
2. The fixing device according to claim 1, wherein the release agent applying unit holds a release agent to be applied,
A contact portion for applying a release agent in contact with the fixing belt, wherein at least the contact portion is located above the auxiliary heating means, and from the fixing nip portion with respect to a passing direction of the recording material. Is also located downstream, at least the contact portion of the release agent applying means is heated relatively quickly in the early stage of operation of the fixing device, and the temperature is stabilized early. Therefore, a temperature difference in the belt width direction of the contact portion is less likely to occur, and as a result, a difference in the amount of the release agent applied in the belt width direction is less likely to occur, and unevenness is less likely to occur in the fixed image. That is, according to the fixing device of the second aspect, an effect is obtained that coating unevenness of the release agent is less likely to occur. According to the fixing device described in claim 3, in the fixing device according to claim 1 or 2, the release agent applying unit includes a release agent holding unit that holds a release agent to be applied, and the fixing belt. And a contact portion for applying a release agent in contact with the fixing nip portion, wherein at least the release agent holding portion is located above the auxiliary heating means, and with respect to a direction in which the recording material passes. Is also arranged downstream, at least the release agent holding unit in the release agent application means,
The fixing device is heated relatively quickly in the early stage of operation, and the temperature is stabilized early. Therefore, a temperature difference in the belt width direction of the release agent holding portion is less likely to occur, and as a result, a difference is less likely to occur in the release agent application amount in the belt width direction, and unevenness occurs in the fixed image. It becomes difficult. In other words, according to the fixing device of the third aspect, the effect that coating unevenness of the release agent hardly occurs is obtained. In particular, when combined with the configuration described in claim 2, the release agent holding section and the contact section in the release agent applying means are heated relatively quickly in the early stage of operation of the fixing device, and the temperature thereof is rapidly increased. Since it becomes stable, the temperature difference in the belt width direction of the release agent holding portion and the contact portion is more unlikely to occur, and as a result, the difference also becomes less likely to occur in the release agent application amount in the belt width direction, The unevenness of the fixed image is further reduced.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. <First Embodiment> FIG. 1 shows a first embodiment of a fixing device according to the present invention.
FIG. 2 is a schematic front view showing the embodiment.

An endless fixing belt 110 is stretched between a heating roller 140 and a backup roller 130 and circulates in a direction indicated by an arrow in the figure, and is pressed against the backup roller 130 via the fixing belt 110. The pressure roller 120 forms a fixing nip N with the fixing belt 110, and the heating roller 14 is disposed downstream of the fixing nip N with respect to the circulation direction of the fixing belt 110.
A recording material S1 on which a toner image is formed, having an oil application roller 150 as a release agent application unit that applies a release agent by abutting on the fixing belt 110 on an upstream side of the fixing belt 110;
Is passed through a fixing nip portion N as indicated by an arrow, and the toner image is heated and melted to be fixed on the recording material S1. A guide 102 guides the recording material.

As the driving roller for rotating the fixing belt 110 and each roller, any roller other than the oil application roller 150 can be used. In this embodiment, the pressing roller 120 is used as the driving roller. Used as a drive roller. That is, the pressure roller 1
Reference numeral 20 denotes a backup roller 13 which is driven to rotate in a direction indicated by an arrow (counterclockwise) in FIG.
0, the fixing belt 110, the heating roller 140, and the oil application roller 150 follow. More specifically, the fixing belt 110 and the backup roller 130 are pressed against the pressing roller 120, so that the fixing belt 110 and the backup roller 13 are pressed.
0 is driven by the pressure roller 120, and the fixing belt 110 is wound around the heating roller 140, so that the heating roller 140 is driven by the fixing belt 110, and the oil application roller 150 is pressed against the fixing belt 110. , The oil application roller 150 moves the fixing belt 1
10.

The heating roller 140 has a heating element 141 as a heat source inside. This heating roller 140
Indicates that the fixing belt 1
It is possible to heat 10 rapidly.

The pressure roller 120 has a halogen lamp 123 as auxiliary heating means inside.

The oil application roller 150 includes a shaft 151,
An oil holding layer 152 as a release agent holding portion made of a thick porous material or fibrous material fixed around the shaft 151 is provided. The oil holding layer 152 is impregnated with release oil, and the surface thereof is covered with an oil-permeable thin film sheet for adjusting the amount of oil applied, for example, a porous PTFE sheet 153. The oil application roller 150 is pressed against the fixing belt 110 by an appropriate urging means (not shown), and is driven to rotate, thereby rotating the fixing belt 1.
Then, a release oil such as a silicone oil is applied while being in contact with the surface of No. 10 (the contact portion is indicated by reference numeral 153a).

The feature of this embodiment is that the oil application roller 150 is located above the auxiliary heating means 123 of the pressure roller 120 and downstream of the fixing nip N with respect to the direction of passage of the recording material S1. It is located at the point. In this embodiment, both the release agent holding portion 152 and the contact portion 153a are located above the auxiliary heating means 123 of the pressure roller 120 and in the fixing nip portion N with respect to the passing direction of the recording material S1. Although at least one of the release agent holding portion 152 and the contact portion 153a is located above the auxiliary heating means 123 of the pressure roller 120 and in the direction in which the recording material S1 passes, May be arranged downstream of the fixing nip portion N.

In this embodiment, when viewed from the axial direction of the backup roller 130, the rotation of the heating roller 140 with respect to a straight line A connecting the rotation center 130 a of the backup roller 130 and the rotation center 120 a of the pressure roller 120. The center 140a is located downstream with respect to the direction of passage of the recording material passing through the fixing nip N (the direction of the arrow S1).

Further, the oil application roller 150 is positioned between the backup roller 13 and the intermediate position between the winding end position of the fixing belt 110 around the backup roller 130 and the winding start position of the heating roller 140.
It is in contact with the fixing belt 110 at a position near zero, that is, at a position near the pressure roller 120. That is, the distance from the ending position of the backup belt 130 around the backup roller 130 to the contact position with the oil application roller 150 in the fixing belt 110 is L2, and the start position of the wrapping around the heating roller 140 from the contact position with the oil application roller 150. If the distance to L1 is L1, L1> L2.

According to the fixing device 100 of this embodiment, the following operational effects can be obtained. (A) Endless fixing belt 110 that is stretched and circulated between heating roller 140 and backup roller 130
A pressure roller 120 that is pressed against the backup roller 130 via the fixing belt 110 to form a fixing nip portion N with the fixing belt 110, and an auxiliary heating unit 123 that heats the pressure roller 120. The fixing belt 110 heated by the heating roller 140.
And the pressure roller 120 heated by the auxiliary heating means 123
As the recording material S1 on which the toner image is formed passes through the fixing nip portion N, the toner image is heated and melted and fixed on the recording material S1. Further, since the release agent applying means 150 for applying the release agent in contact with the fixing belt 110 is provided, an offset phenomenon in which the toner image on the recording material S1 is transferred to the fixing belt 110 is less likely to occur, and The release agent applying means 150 applies the release agent by abutting on the fixing belt 110 downstream of the fixing nip portion N and upstream of the heating roller 140 in the circulation direction of the fixing belt 110, so that the heating roller 1
The fixing belt 110 heated at 40 is moved to the fixing nip N
Is prevented from being lowered by the application of the release agent before reaching the temperature. According to the fixing device 100, the release agent applying unit 150 is located above the auxiliary heating unit 123 of the pressure roller 120 and from the fixing nip N in the recording material passing direction (see the arrow S <b> 1). Is also located downstream, the radiant heat from the auxiliary heating means 123 and the hot air flow reach the release agent applying means 150 almost without being hindered by the backup roller 130 and the fixing belt 110. Therefore, the release agent applying unit 150 is directly heated not only by the contact with the fixing belt 110 but also by the radiant heat from the auxiliary heating unit 123 and the hot air flow. For this reason, the release agent applying means 150 is heated relatively quickly in the early stage of the operation of the fixing device 100, and the temperature is stabilized early. Therefore, even if the fixing belt 110 in which the temperature difference occurs in the width direction (the direction orthogonal to the paper surface of FIG. 1) due to the recording material S1 passing through the fixing nip N, even if the fixing belt 110 Since the difference is not so much reflected on the temperature of the release agent applying unit 150, the temperature difference in the belt width direction of the release agent applying unit 150 is less likely to occur, and as a result, the release of the release agent applying unit 150 in the belt width direction becomes difficult. Differences in the amount of the mold agent applied hardly occur, and unevenness in the fixed image hardly occurs. As described above, according to the fixing device 100, an effect is obtained that coating unevenness of the release agent is less likely to occur. Note that such an effect is achieved by the release agent holding unit 15 in the oil application roller 150 as the release agent application unit.
2. At least one of the contact portions 153a is above the auxiliary heating means 123 of the pressure roller 120, and
It is also obtained when the recording material S1 is disposed downstream of the fixing nip N with respect to the passing direction of the recording material S1.

(B) In this embodiment, both the release agent holding portion 152 and the contact portion 153a are located above the auxiliary heating means 123 of the pressure roller 120 and in the direction in which the recording material S1 passes. Since the release agent holding unit 152 and the contact unit 153a in the release agent application unit 150 are disposed downstream of the fixing nip portion N, the fixing device 1
In the early stage of the operation of 00, heating is performed relatively quickly, and the temperature is stabilized early. Therefore, a temperature difference in the belt width direction between the release agent holding portion 152 and the contact portion 153a is less likely to occur, and as a result, a difference is more unlikely to occur in the release agent application amount in the belt width direction, and the toner is fixed. Non-uniformity is further reduced in the image.

(C) The rotation center 13 of the backup roller 130 when viewed from the axial direction of the backup roller 130.
0a and the rotation center 120a of the pressure roller 120, the rotation center 140a of the heating roller 140 is
Since the recording material passing through the fixing nip portion N is located downstream with respect to the passing direction, the hot air flow heated by the auxiliary heating means 123 of the pressure roller 120 is guided by the fixing belt 110. Release agent application means 1
It will be easier to hit 50. Therefore, the release agent applying means 1
50 is heated more quickly in the early stage of the operation of the fixing device 100, and the temperature is stabilized earlier. Therefore, the temperature difference in the belt width direction of the release agent applying unit 150 is more unlikely to occur, and as a result, the difference in the amount of the release agent applied in the belt width direction is more unlikely to occur, and the fixed image is fixed. Unevenness is more unlikely to occur.

(D) Since the oil application roller 150 also has a function as a cleaning unit for removing the toner offset to the belt 110, the toner offset to the fixing belt 110 is transferred onto the recording material. This prevents a situation in which image stains occur. Here, for example, in the case of the conventional fixing device shown in FIG. 4, as described above, the temperature of the oil application roller R4 hardly rises particularly in the early stage of operation of the fixing device. Although the capacity is hardly improved, according to the fixing of this embodiment, the oil application roller 150
However, the toner is quickly heated in the early stage of operation of the fixing device 100, and the temperature rises quickly, so that good cleaning performance by the oil application roller 150 can be obtained even in the early stage of operation of the fixing device. Moreover, the fixing belt 110 is heated by the auxiliary heating means 123 of the pressing roller 120 from the fixing nip portion N to the oil application roller 150, so that the fixing belt 110 is heated.
Solidification of the toner (ie, the fixing belt 1)
In this case, an increase in the fixing force of the toner to the toner 10 is suppressed, so that a better cleaning performance can be obtained.

(E) The oil application roller 150 is located between the pressure belt 120 and the intermediate position of the fixing belt 110 between the winding end position of the backup roller 130 and the winding start position of the heating roller 140. Since the fixing belt 110 is in contact with the auxiliary heating unit 123 at a position close to the auxiliary heating unit 123, the temperature of the release agent applying unit 150 is stabilized more quickly.

<Second Embodiment> FIG. 2 is a front view showing a second embodiment of the fixing device according to the present invention, and FIG.
(B) is the schematic which shows the principal part respectively. In these figures, the same or corresponding parts as those in the above-described first embodiment are denoted by the same reference numerals.

The features of this embodiment are shown in FIGS.
As shown in (b), the inclination γ of the external tangent C between the backup roller 130 and the heating roller 140 on the side where the oil application roller 150 is in contact is toward the heating roller 140 (upward in the figure). Pressure roller 12
The point is inclined to the upstream side in the recording material passing direction (the direction of arrow S1) with respect to the perpendicular D passing through the zero rotation center 120a.
The inclination γ is in the range from −45 ° to + 45 °, preferably in the range from −20 ° to + 20 °.

With this configuration, the following operation and effect can be obtained in addition to the operation and effect obtained by the above-described first embodiment. That is, the inclination γ of the external tangent C between the backup roller 130 and the heating roller 140 on the side where the oil application roller 150 contacts.
Is inclined toward the heating roller 140 (upward in the figure) and more upstream than the perpendicular D in the direction in which the recording material passes (the direction of the arrow S1), so that the influence of vibration due to the weight of the belt 110 is small. The oil application roller 150
As a result, the contact state between the fixing belt 110 and the fixing belt 110 is stabilized, and as a result, uneven application of oil can be more reliably prevented.

Hereinafter, a specific configuration of this embodiment will be described mainly with reference to FIG. Fixing belt 11
Reference numeral 0 indicates a surface layer (for example, a silicone rubber layer) having excellent releasability from a recording material and toner formed on the surface of a thin metal (for example, nickel) belt base material.
In FIG. 2, reference numeral 111 denotes the backup roller 13.
This is a thermistor for detecting the surface temperature of the fixing belt 110 at a portion where the fixing belt 110 is wound around zero. This thermistor 11
Reference numeral 1 is provided upstream of a pressure contact portion (fixing nip portion) N with the pressure roller 120.

The backup roller 130 has a metal core 131 and a relatively thick elastic layer 132 provided on the surface of the core 131.
At 31a, the fixing device 100 is rotatably supported on the side plate 101 of the frame.

The heating roller 140 is formed in a pipe shape from a material having excellent thermal conductivity (for example, aluminum), and a heating element 141 as a heat source is disposed inside the heating roller 140. The heating roller 140 can rapidly heat the fixing belt 110 at a portion where the fixing belt 110 is wound. The heating roller 140 of this embodiment is configured as a tension roller, and is urged by a suitable urging means (not shown) in the tensioning direction of the fixing belt 110 (the direction of arrow F2 in FIG. 3A). In FIG. 2, reference numeral 143 denotes a thermistor for detecting the temperature of the heating roller 140.

The pressure roller 120 includes a pipe-shaped core material 121 having excellent thermal conductivity, an elastic layer 122 provided on the surface of the core material 121 and having a thickness smaller than that of the elastic layer 132 of the backup roller 130. A surface layer 122 a formed on the surface of the elastic layer 122 and having excellent releasability from a recording material and toner is provided. A halogen lamp 123 as a heat source is disposed inside the core 121. The pressure roller 120 is rotatably supported by the frame side plate 101 of the fixing device 100, and is driven in a direction indicated by an arrow in FIG. 2 by a driving unit (not shown) provided in an image forming apparatus main body provided with the fixing device 100. It is driven to rotate. The pressure roller 120 is immovably mounted in the radial direction, and is pressed against the backup roller 130 via the fixing belt 110 by the elastic force of the elastic layer 122 and the elastic layer 132 of the backup roller 130. I have. Since the elastic layer 132 of the backup roller 130 is thicker than the elastic layer 122 of the pressure roller 120, the pressure contact portion (that is, the fixing nip portion N) is formed in a convex shape toward the backup roller 130. In FIG.
Is a thermistor for detecting the surface temperature of the pressure roller 120.

The oil application roller 150 includes a shaft 151,
An oil holding layer 152 made of a thick porous material or a fibrous material fixed around the shaft 151 is provided. The oil holding layer 152 is impregnated with a release oil, and the surface thereof is made of an oil-permeable thin film sheet for adjusting the amount of oil applied, for example, porous PTFE.
Covered with sheet 153. Oil application roller 150
Is pressed against the fixing belt 110 by an appropriate urging means (not shown) and is driven to rotate, thereby applying release oil such as silicone oil to the surface of the fixing belt 110. In FIG. 2, reference numeral 154 denotes a cleaning member made of felt or the like for cleaning the surface of the oil application roller 150, and is in pressure contact with the surface of the oil application roller 150.

A guide 1 guides a recording material on which a toner image has been formed (transferred) to a press contact portion (fixing nip portion) N between a fixing belt 110 and a pressure roller 120.
02 is provided. Downstream of the nip portion N, there are provided a paper discharge roller pair 103 and a guide 104 for guiding the fixed recording material to a paper discharge path (not shown) of the image forming apparatus. Each of the thermistors is connected to a control unit (not shown), and the control unit controls the amount of power supplied to each of the heat sources 123 and 141 according to the temperature detected by each thermistor.

[0033]

EXAMPLE A further specific example will be described. (Regarding the distances L1 and L2 described above) The distance L2 from the winding end position of the fixing belt 110 to the backup roller 130 to the contact position with the oil application roller 150 is about 13.9 mm, and the contact with the oil application roller 150 is about 13.9 mm. The distance L1 from the position to the winding start position on the heating roller 140 is about 23.2 mm (L1 = 23.
2 mm> L2 = 13.9 mm).

Pressure roller 12 (with respect to angle γ described above)
The inclination angle γ of the external tangent C between the backup roller 130 and the heating roller 140 on the side where the oil application roller 150 is in contact with the perpendicular D passing through the zero rotation center 120a.
Is about 28.35 °.

(Regarding Pressure Roller 120) Pressure Roller 1
Halogen lamp 123 (FIG. 2)
Refer to). The heat value of the halogen lamp 123 is 20
Although it can be set appropriately in the range of 0 to 300 W, it is more preferably about 230 W.

(Regarding the heating roller 140) The heating means 141 disposed in the hollow portion of the roller is a halogen lamp.
The heat value can be appropriately set in the range of 650 to 850 W, but is more preferably about 720 W.

The roller hardness (with respect to the oil application roller 150) can be appropriately set within the range of JIS-A5 to 30 °, but is more preferably about 20 °. Surface roughness is Ra
It can be set appropriately within the range of 0.5 to 3 μm, but is more preferably Ra about 1 μm. Oil impregnated layer 152
a is made of sponge or paper. Oil supply layer 15
2b is made of felt or synthetic leather and has a layer thickness of 1.2.
mm. The surface layer 153 is made of porous PTFE (4
(Fluorinated ethylene polymer) resin. The layer thickness can be appropriately set within a range of 30 to 120 μm, but is more preferably about 60 μm. The material of the release agent is dimethyl silicone oil (amino modified silicone oil is also acceptable). The viscosity (at 20 ° C.) can be appropriately set in the range of 80 to 400 centistokes, but is more preferably about 100 centistokes. Fixing belt 1
The contact load (pressing load) to 10 is a total load of 0.5 or more and 2K
g or less, but more preferably 1K
g. Oil application roller 150 and fixing belt 1
The contact width with 10 (length in the belt moving direction) is 3 m
m. (Modification Example of Oil Application Means) In addition to the oil application roller 150 of a release agent impregnated type, a pad impregnated with a release agent,
A blade or the like may be employed. In the case of the release agent impregnated type, fixed load fixing is preferable to fixed position fixing. This is because the outer diameter of the roller decreases when the impregnation amount decreases due to the application of the release agent, and the oil application roller 150 and the belt 11 also function as tension applying means when fixed at a fixed position.
This is because the contact with 0 may become unstable and coating unevenness may occur. Further, the oil application roller 150 is not a release agent impregnated type, and a cleaning roller 155 is provided around the oil application roller 150 as shown by a virtual line in FIG.
Alternatively, a release agent supply roller 156 may be provided. In this case, as the oil application roller 150, a rigid roller made of aluminum or stainless steel, or an elastic roller made of silicone rubber or fluorine rubber can be used. Further, if necessary, a surface layer having releasability from silicone rubber or fluororesin may be provided. A similar roller can be used as the cleaning roller. A cleaning blade can be used instead of the cleaning roller. As the release agent supply roller 156, the aforementioned release agent impregnated oil application roller can be used.

(Regarding Arrangement of Rollers, etc.) Heating Roller 1
40 and the backup roller 130 have a center distance of 40.
The distance between the backup roller 130 and the pressure roller 120 is about 35.2 mm. The axial distance between the backup roller 130 and the release agent applying roller 150 is about 38.9 mm, and the axial distance between the heating roller 140 and the release agent applying roller 150 is about 39.18 mm.
As shown in FIG. 3B, the rotation centers 130a and 12a of the backup roller 130 and the pressure roller 120, respectively.
0a, and the respective rotation centers 130a, 140a of the backup roller 130 and the heating roller 140.
Is set to about 4.43 ° on the downstream side of the recording material conveyance with respect to the straight line A. The angle at which the guide 102 is formed is such that the angle δ formed by the recording material conveying surface F with respect to the horizontal line G (the mounting surface of the image forming apparatus on which the fixing device 100 is mounted) G is about 31 °. This angle δ is 10 ° or more and 50
° can be appropriately set in the range of less than or equal to, more preferably 31
°. When the suction fan 160 for sucking the recording material along the guide 102 is provided, the posture of the leading end of the recording material to the fixing nip N is stabilized, and the trailing end of the recording material floats to enter the fixing nip N. It is more preferable because it is possible to prevent the rear end of the recording material from contacting the backup roller 130 before and the image is disordered.
Recording material entry angle (guide surface F and fixing nip horizontal line E)
(The angle formed between the backup roller 130 and a line perpendicular to the rotation center of the pressure roller 120) β is about 4 °. The contact position between the discharge roller pairs 103 and the center of the fixing nip N (the center in the recording material conveyance direction)
The angle ε formed by the straight line H connecting
It is about 1.5 °.

Although the embodiments and examples of the present invention have been described above, the present invention is not limited to the above-described embodiments or examples, and can be modified as appropriate within the scope of the present invention. It is.

[0040]

According to any one of the fixing devices according to the first to third aspects, the effect that coating unevenness of the release agent hardly occurs can be obtained.

[0041]

[Brief description of the drawings]

FIG. 1 is a schematic front view showing a first embodiment of a fixing device according to the present invention.

FIG. 2 is a front view showing a second embodiment of the fixing device according to the present invention.

FIGS. 3A and 3B are schematic diagrams showing a main part of the fixing device, respectively.

FIG. 4 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 fixing device 110 fixing belt 120 pressure roller 123 auxiliary heating means 130 backup roller 140 heating roller 150 oil applying roller (release agent applying means) 152 release agent holding section 153a contact section N fixing nip section

Continued on the front page (72) Inventor Naoyuki Okumura 3-3-5 Yamato, Suwa City, Nagano Prefecture Inside Seiko Epson Corporation (72) Inventor Kazutoshi Fujisawa 3-3-5 Yamato Suwa City, Nagano Prefecture Seiko Epson Corporation F-term (reference) 2H033 AA03 BA44 BB00

Claims (3)

[Claims] An endless fixing belt stretched and circulated between a heating roller and a backup roller, and a fixing nip portion is formed between the fixing belt and the backup belt by being pressed against the backup roller via the fixing belt. A pressure roller to be formed; an auxiliary heating means for heating the pressure roller; and a contact roller which is in contact with the fixing belt downstream of the fixing nip portion and upstream of the heating roller in the circulation direction of the fixing belt. Having a release agent applying means for applying a mold agent,
A fixing device for passing the recording material on which the toner image is formed through the fixing nip portion to heat and fuse the toner image to fix the toner image on the recording material, wherein the release agent applying unit is more than the auxiliary heating unit. A fixing device, which is disposed above and downstream of the fixing nip with respect to the recording material passing direction. 2. The release agent applying unit has a release agent holding unit for holding a release agent to be applied, and a contact unit for applying the release agent in contact with the fixing belt. 2. The apparatus according to claim 1, wherein at least the contact portion is disposed above the auxiliary heating means and downstream of the fixing nip portion with respect to the recording material passing direction.
The fixing device as described. 3. The release agent applying unit includes a release agent holding unit that holds a release agent to be applied, and a contact unit that contacts the fixing belt and applies the release agent. 2. The image forming apparatus according to claim 1, wherein at least the release agent holding unit is disposed above the auxiliary heating unit and downstream of the fixing nip with respect to the recording material passing direction. 2. The fixing device according to 2.