JPH07219380A - Fixing device - Google Patents

Abstract

PURPOSE:To prevent a shear in an image from causing due to a distortion of a fixing roll by driving another driving mechanism with the rotary force of the roll located on the upstream side from the pressure roll and braking the transporting of an endless belt in the area of the pressurized contact area with the pressure roll. CONSTITUTION:The heat resistant endless belt 15 is arranged so as to be held in pressurized contact with the surface of the thermal fixing roll 1 over a prescribed nipping width, when the thermal fixing roll 1 is rotated, the rotary force is transmitted to the endless belt 15 through the pressure roll 25 held in pressurized contact with the thermal fixing roll 1, and the endless belt 25 extended by the rolls 22 to 25 is rotary driven. In the mean time, the release agent supplying device drive gear 44 is driven by the rotary force of the roll 24 located on the right upstream side from the pressure roll 25, among the rolls 22 to 25 extending the endless belt 15, thus the prescribed braking force is applied to the endless belt 15 held in pressurized contact with the fixing roll 1, consequently the speed difference between the fixing roll 1 and the endless belt 15 in the nip part is prevented from occurring.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called heating roll type fixing device for contact heat fixing an unfixed toner image on a recording medium in an image forming apparatus such as a copying machine, a facsimile machine, a printer or the like.

[0002]

2. Description of the Related Art Conventionally, in image forming apparatuses such as copying machines and printers, it has been necessary to fix an unfixed toner image transferred onto a recording sheet to make it a permanent image. JP-A-52-69337, JP-A-60-151677, JP-A-60-151681
JP-A-62-14675, JP-A-60-
As disclosed in Japanese Unexamined Patent Publication No. 104852, etc., and Japanese Utility Model Laid-Open No. 2-30961, an endless belt is brought into pressure contact with a fixing roll, and a long nip portion formed between the fixing roll and the endless belt, By passing the recording paper onto which the unfixed toner image has been transferred, heat and pressure are applied to the unfixed toner image for a long time so that even a color image with a large amount of unfixed toner can be well fixed. Various configurations have already been proposed.

However, in the fixing device according to the above proposal, heat and pressure are applied to the unfixed toner image on the recording paper for a long time by the long nip portion formed between the fixing roll and the endless belt. Therefore, even if a color image with a large amount of unfixed toner can be fixed well, in the case of a color image with a large amount of unfixed toner, the toner acts as an adhesive and the recording paper adheres to the fixing roll. Since it is easy to do so, it is necessary to surely peel the recording paper from the fixing roll by using the peeling claw, but the problem that the image fixed on the recording paper is damaged by the peeling claw and the image quality is deteriorated have.

Therefore, the present inventors have already proposed the following fixing device in order to solve the above problems (Japanese Patent Application No. 3-252097).

As shown in FIG. 6, this fixing device is a heat fixing roll type fixing device for fixing an unfixed toner image 101 on a transfer material 100, and an elastic member 10 of 0.5 mm or more is used.
2 is covered with a heat fixing roll 103, and a heat-resistant belt 108 stretched around a plurality of support rolls 104 to 107.
And the heat-resistant belt 108 and the fixing roll 103.
A heat resistant belt 108 is wound around the fixing roll 103 by a predetermined angle so as to form a nip between the pressure roller 107 and the pressure roller 107 inside the heat resistant belt 108 at the exit of the nip. This is a so-called belt nip fuser configured to cause the elastic body 102 of the heat fixing roll 103 to be distorted by being pressed against the heat fixing roll 103 via the heat resistant belt 108.

This fixing device is a novel belt nip type fixing device applicable not only to black and white images but also to a color copying machine. The fixing device thermally fixes the pressure roll 107 via the heat-resistant belt 108. By pressing it against the roll 103, the elastic body 102 of the heat fixing roll 103 is distorted so that the recording paper can be separated from the heat fixing roll 103 by the rigidity of the paper itself, and a large amount of toner is deposited. Even when color-fixing recording paper with thin paper thickness and weak stiffness, it does not require a peeling claw and can be peeled at the exit of the belt nip without using any peeling device. It is a belt nip type fixing device having a characteristic of "stripping").

[0007]

However, the above-mentioned prior art has the following problems. That is, in the case of the fixing device proposed by the applicant, the heat-resistant belt 108 is wound around the fixing roll 103 at a predetermined angle so as to form a nip between the heat-resistant belt 108 and the fixing roll 103. At the exit of the nip, a pressure roll 107 is disposed inside the heat-resistant belt 108, and the pressure roll 107 is pressed against the heat-fixing roll 103 via the heat-resistant belt 108, whereby an elastic body of the heat-fixing roll 103 is formed. It is configured to cause distortion in 102.

By the way, the inventors of the present invention actually made a prototype of this belt nip type fixing device and conducted a fixing experiment by changing the load of the pressure roll 107. As a result, the belt nip type proposed by the applicant of the present invention was obtained. It was found that there is a new problem of image defects in the fixing device. The problem is that when the load of the pressure roll 107 is increased, an image shift occurs in which the toner image 101 fixed on the transfer material 100 shifts from a certain load or more.

FIG. 8 shows the result of the investigation by the present inventors on the relationship between the image shift and the load of the pressure roll.

Further, the inventors of the present invention have considered the mechanism for causing the image shift as follows.

Generally, as shown in FIG. 7, when the pressure roll 121 is brought into pressure contact with the surface of the elastic roll 120, the surface of the elastic roll 120 is distorted and deformed by the pressure contact force received from the pressure roll 121. As described above, when strain deformation occurs on the surface of the elastic roll 120, the circumferential length of the elastic roll 120 increases correspondingly. Assuming that the radius of the elastic roll 120 is r, the peripheral length L of the elastic roll 120 before deformation is L = 2πr, whereas the peripheral length L ′ of the elastic roll 120 after deformation is L. '= 2πr (1+
ε). Therefore, the strain amount ε is ε = (L′−
L) / L = L '/ L-1. The surface velocity of the elastic roll 120 is affected by the strain ε, and when the strain ε exists in the circumferential direction of the elastic body, the surface velocity V of the portion where the strain ε exists is V = (1 + ε). It becomes V ₀ . Here, V ₀ represents the surface velocity in the state of ε = 0 without distortion.

In the belt nip type fixing device according to the above proposal, the pressure roll 10 is provided at the nip outlet.
Strain is generated in the circumferential direction due to the load from 7.
Then, the speed V of the portion where the distortion is generated and the speed V ₀ between the belt 108 and the nip region (here, ε =
There is a slight difference in velocity between (and 0). In this way, when there is a difference in the surface speed of the fixing roll 107 between the entrance side and the exit side of the nip within the same belt nip, when the speed difference becomes larger than a certain value, the surface of the fixing roll 107 is not changed until then. The paper that is in close contact with the sheet cannot absorb the speed difference, and is conveyed at the surface speed of the distorted portion where the pressure roll 107 having a high nip pressure, that is, a strong conveying force is in pressure contact, and finally an image shift occurs. It is a hypothesis that it will end up.

The surface strain of the elastic roll under a certain load can be measured as follows. Generally, when the hard roll and the soft roll are pressed against each other under a certain load, the surface of the soft roll is elastically deformed in the nip region, and a certain strain ε is generated in the circumferential direction of the surface. When the roll pair is rotated in this state and the recording paper passes through the nip area, the recording paper is conveyed in the distorted nip area. Therefore, the length L ′ of the recording sheet sent out by one rotation of the elastic roll that has been distorted is actually conveyed by the strain ε in the circumferential direction from the length L of the roll circumference (when ε = 0). The amount increases.

That is, ε = {the length L of the recording paper fed in one rotation of the elastic roll / the peripheral length of the elastic roll (when ε = 0)} − 1. From this equation, the actual strain ε can be measured. The strain ε in the present invention is the value of this measurement method.
When measuring the strain ε with an actual belt nip fuser, it is necessary to make the tension of the belt zero.

Therefore, in order to solve the above-mentioned problems, the present inventors wound a part of an endless belt stretched by a plurality of rolls around a fixing roll coated with an elastic body to form a nip portion. In a fixing device that is formed and presses a pressure roll against the fixing roll from the inner peripheral side of the endless belt at the exit part of the nip portion via the endless belt, a region of the pressure roll that presses against the fixing roll. Has already proposed a fixing device configured to provide a braking force applying means for applying a braking force to the conveyance of the endless belt in Japanese Patent Application No. 5-3.
6699).

Since this fixing device is provided with a braking force applying means for exerting a braking force on the conveyance of the endless belt in the region of the pressure roll which is in pressure contact with the fixing roll, the endless belt is provided at the exit of the nip portion. Even when the pressure roll is pressed against the fixing roll through the endless belt from the inner peripheral side of the belt, the elastic body of the fixing roll is distorted and deformed to separate the transfer medium from the fixing roll by itself, The braking force can be applied to the conveyance of the endless belt in the region of the pressure roll that is in pressure contact with the fixing roll by the braking force applying unit, and the belt conveyance speed of the fixing roll in the region of the pressure roll is increased by the amount of strain deformation of the elastic body. Can be suppressed, and image misregistration occurs at the nip portion between the fixing roll and the belt. So that the it can be prevented.

However, in the case of the fixing device according to this proposal, it is necessary to newly provide a braking force applying means for exerting a braking force on the conveyance of the endless belt in the area of the pressure roll that is in pressure contact with the fixing roll. In addition to the increase in cost, braking is applied to the conveyance of the endless belt that follows the rotation of the fixing roll, so that energy is wastefully consumed and the driving force of the fixing roll, etc. is effectively used. It has a problem that it can not be done.

The present invention has been made to solve the above-mentioned problems of the prior art. The object of the present invention is to remove the recording medium from the surface of the fixing roll without using a peeling device. Of course, it is possible to prevent the occurrence of image shift due to distortion of the fixing roll,
Moreover, it is an object of the present invention to provide a fixing device which does not increase the cost and wastefully consumes the driving force for driving the fixing roll and the like.

[0019]

That is, the present invention is
A fixing roll coated with an elastic body is wound with a part of an endless belt stretched by a plurality of rolls to form a nip portion, and at the exit portion of the nip portion, from the inner peripheral side of the endless belt, the endless belt is formed. In a fixing device in which a pressure roll is pressed against the fixing roll via a belt, among a plurality of rolls around which the endless belt is stretched, the rotational force of the roll positioned upstream of the pressure roll is used to By driving the driving mechanism, a braking force is applied to the conveyance of the endless belt in the region of the pressure roll that is in pressure contact with the fixing roll.

As another driving mechanism which is driven by utilizing the rotational force of the roll positioned on the upstream side of the pressure roll,
For example, a release agent supply device that supplies a release agent to the surface of the fixing roll is used.

[0021]

According to the present invention, of the plurality of rolls around which the endless belt is stretched, the rotational force of the roll positioned upstream of the pressure roll is used to drive the other drive mechanism to press the roll against the fixing roll. Since the braking force is applied to the conveyance of the endless belt in the area of the pressure roll, the braking force acting means for applying the braking force to the conveyance of the endless belt in the area of the pressure roll that is in pressure contact with the fixing roll is separately provided. Since it is not necessary to provide the recording medium on the surface of the fixing roll, it is possible to peel the recording medium from the surface of the fixing roll without increasing the cost and wasting the driving force for driving the fixing roll. Furthermore, it is possible to prevent the occurrence of image shift due to the distortion of the fixing roll.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to illustrated embodiments.

FIG. 2 shows an embodiment of the fixing device according to the present invention.

In the figure, reference numeral 1 denotes a heat fixing roller, and the heat fixing roller 1 is driven by a drive motor 27 along a direction of an arrow to a predetermined speed, for example 250 mm / s.
It is adapted to be rotationally driven at a speed of ec. The heat fixing roller 1 has, for example, an outer diameter of 46 mm and an inner diameter of 40 mm.
The aluminum cylinder 3 is provided with HTV silicon rubber (rubber hardness 45 degrees) as the elastic layer 20 with a thickness of 2 mm on the surface of the aluminum cylinder 3. On the surface of 20, silicon RTV rubber as a top coat layer 21 is further 50 μm.
The top coat layer 21 is dip-coated to a thickness of m, and the surface of the top coat layer 21 is finished in a state close to a mirror surface.

A 400 W halogen lamp 5 is disposed as a heat source inside the aluminum cylinder 3, and the heat fixing roller 1 is controlled by the halogen lamp 5 so that the surface temperature thereof becomes a predetermined temperature. It is designed to be heated from the inside. The surface temperature of the heat fixing roller 1 is detected by the temperature sensor 6 in contact with the surface of the heat fixing roller 1, and is controlled by a temperature controller (not shown) so that the surface temperature of the heat fixing roller 1 becomes, for example, 150 ° C. It is configured.

Further, on the surface of the heat fixing roller 1,
As a release agent, dimethyl silicone oil viscosity 300 cs
(KF-96: manufactured by Shin-Etsu Chemical Co., Ltd.) is uniformly supplied by the release agent supply device 9. This release agent supply device 9 includes a release agent supply roll 9b partially immersed in an oil pan containing the release agent 9a, and an amount of the release agent supplied by the release agent supply roll 9b. The blade 9c for adjusting and the release agent 9a attached to the surface of the release agent supply roll 9b are supplied through the intermediate roll 9d, and the release agent 9a is applied to the surface of the heat fixing roll 1 It is composed of a roll 9e. And this release agent supply device 9
Rotates the release agent coating roll 9e and rotates the intermediate roll 9d and the release agent supply roll 9b that are driven by the release agent coating roll 9e, thereby releasing the release agent on the surface of the heat fixing roll 1. 9a is applied and supplied.

A heat-resistant endless belt 15 is arranged on the surface of the heat fixing roller 1 so as to come into pressure contact with it over a predetermined nip width. The endless belt 15 has, for example, a thickness of 75 μm, a width of 300 mm, and a circumference of 2
It is made of 88 mm polyimide film, and is made of four stainless steel rolls 22, 23, 24 and 25.
It is stretched with a tension of 10 kg. The diameter of each of the stainless steel rolls 22, 23, 24, 25 is 22.
mm, 20 mm, 20 mm, and 18 mm. Among them, the pressure roll 25 having a diameter of 18 mm is fixed by the compression coil spring 26 as a pressurizing means.
The belt 15 is pressed against the fixing roller 1 by being urged toward the center of the fixing roller 1. The wrapping angle of the belt 15 around the fixing roll 1 is set to 45 degrees, and the width of the belt nip at this time is 19.6 mm. The outlet of the belt nip is the pressure roll 25.
Is crimped through the belt 15 with a load of 20 kg. Therefore, the elastic layer 20 of the fixing roll 1 is deformed,
Strain ε is generated on the surface.

Strain ε generated on the surface of the fixing roll 1
Is calculated by the following equation as described above. ε = {length L of recording sheet sent out by one rotation of the fixing roll 1 / perimeter of the fixing roll 1 (when ε = 0)}-1 The strain ε generated on the surface of the fixing roll 1 is measured. In that case, the tension of the belt 15 is set to zero and the measurement is performed.

By the way, in this embodiment, of the plurality of rolls around which the endless belt is stretched, the driving force of the roll positioned upstream of the pressure roll is used to drive the other drive mechanism to thereby fix the fixing roll. A braking force is applied to the transport of the endless belt in the region of the pressure roll that is in pressure contact with the.

That is, four stainless steel rolls 22, 23 around which the heat-resistant endless belt 15 is stretched,
As shown in FIG. 1 and FIG. 3, the stainless steel roll 24 located immediately upstream of the pressure roll 25 among 24 and 25 should be driven by the rotational force thereof to drive the release agent supply device. Gear train is installed.

In FIGS. 1 and 3, reference numeral 30 denotes an input gear attached to the drive shaft 32 of the drive motor 31, and the input gear 30 is meshed with the first gear 33 for rotationally driving the fixing roll 1. Has been done. In addition, this first gear 33
The second gear 3 having a smaller number of teeth than the first gear 33.
4 are integrally provided. The first and second gears 33 and 34 are rotatably attached to the shaft 35 via bearings. Further, the second gear 34 is meshed with the third gear 36, and the third gear 3
A fourth gear 37 is fixed to 6 so as to rotate integrally. The fourth gear 37 is meshed with a drive gear 38 fixed to the rotary shaft member 1 a of the heat fixing roll 1. Then, by rotating the input gear 30 by the drive motor 31, the first to fourth gears 33,
The thermal fixing roll 1 is configured to be rotationally driven via 34, 36, 37 and the drive gear 38.

When the heat fixing roll 1 is rotationally driven as described above, the rotational force of the heat fixing roll 1 is transmitted to the endless belt 15 via the pressure roll 25 that is in pressure contact with the heat fixing roll 1, and the four fixing rollers 1 are rotated. Stainless steel rolls 22, 2
Endless belt 1 stretched by 3, 24, 25
5 is driven to rotate in the direction of the arrow.

Further, in this embodiment, the release agent applying roll 9e of the release agent supplying device 9 is rotationally driven by utilizing the rotational force of the tension roll 24 around which the endless belt 15 is stretched. There is.

That is, as shown in FIGS. 1 and 3, a fifth gear 39 is attached to the rotary shaft 24a of the tension roll 24, and the fifth gear 39 is the first gear 39.
The second gear 33, 34 is meshed with a sixth gear 40, which is rotatably supported on the same shaft 35 as the shaft 35. The sixth gear 40 is the same as the fourth gear 3 described above.
The seventh gear 41 is meshed with a seventh gear 41 that is rotatably supported on the outer periphery of the seventh gear 41.
And the drive gear 4 fixed to the rotating shaft 9e ′ of the release agent applying roll 9e of the release agent supplying device 9 via the ninth gear 43.
4 is meshed. The rotational force of the tension roll 24, which is rotated by the heat fixing roll 1, is the fifth to ninth gears 39, 40, 41, 42, 43 and the drive gear 4.
4 and further transmitted via the gears 45 and 46 to the release agent applying roll 9e of the release agent supplying device 9, and the rotational force of the tension roll 24 causes the release agent applying roll 9e of the release agent supplying device 9 to move. It is designed to be driven to rotate.

A drive gear 46 fixed to the rotary shaft of the release agent coating roll 9e, and a gear 45 engaged with the drive gear 46,
Since a large rotational drive torque acts on the 44 and the ninth gear 43, it is desirable to use a metal gear made of a sintered metal or the like as the drive gear 44 and the ninth gear 43. As the gears 30, 33, ... 42 other than the above, plastic gears are used from the viewpoint of reduction of rotation noise, maintenance, and the like.

The fixing roll 1 is rotatably driven by the drive motor 27 at a speed V ₀ = 250 mm / sec. At this time, since the strain ε (for example, a value ε = 4% suitable for performing self-stripping) is generated on the surface of the fixing roll 1 at the nip portion with the pressure roll 25, the tension of the belt 15 is zero. In the case of, the surface velocity Vε of the fixing roll 1 in the nip portion is Vε = 260 mm
/ S. In this state, the tension of the belt 15 is changed to the original 10k.
When the belt 15 is driven back to g, the speed of the belt 15 at the nip portion is driven to rotate at 254 mm / s.

Therefore, four stainless steel rolls 22, 23, 24, around which the heat-resistant endless belt 15 is stretched,
Of the 25, by the rotational force of the stainless tension roll 24 located immediately upstream of the pressure roll 25,
By driving the release agent supply device 9, the fixing roll 1
By applying a predetermined braking force to the endless belt 15 that is in pressure contact with the endless belt 15, the speed difference in the nip portion between the fixing roll 1 and the endless belt 15 is suppressed as much as possible, and the image fixed in the nip portion is displaced. It is designed to prevent

With the above arrangement, the fixing device according to this embodiment prevents the occurrence of image shift in the fixing section as follows. That is, in the above fixing device, as shown in FIG. 1, the recording paper 51 carrying the toner image 50 is carried out.
Enters between the heat fixing roller 1 and the endless belt 15, and while passing through the nip portion between the heat fixing roller 1 and the endless belt 15, the toner image 50 is fixed on the recording paper 51 by heat and pressure. To be done.

Then, in the nip portion between the heat fixing roller 1 and the endless belt 15, the recording paper 51 on which the fixing processing is performed is formed by fixing the endless belt 15 to the fixing roller 1.
When passing through the pressure roll 25 that is brought into pressure contact with the surface of the heat fixing roller 1, the pressure roll 25 that is brought into pressure contact with the surface of the fixing roller 1 is curved in a concave shape in the direction of peeling from the surface of the heat fixing roller 1 as shown in FIG. To be done. Therefore, the leading edge of the recording paper 51 is deformed into a concave shape in the direction of peeling from the surface of the fixing roller 1, and is peeled from the surface of the fixing roller 1 by the waist (rigidity) of the recording paper 51 itself, that is, self-stripping. Endless belt 15
Is discharged from the fixing device to the outside. Therefore,
Even in the case of a color image in which a large amount of toner is fixed on the recording paper 51, the recording paper 51 is reliably separated from the surface of the heat fixing roll 1 without using any separating means such as a separating claw. It is possible.

At this time, of the rolls 22, 23, 24, 25 supporting the endless belt 15, the roll 24 located immediately upstream of the pressure roll 25 drives the release agent supply device 9 to rotate. It is configured to be.

The fixing roller 1 is driven by a drive motor 27.
In the direction of arrow 28, for example, speed V ₀= 250 mm / s
It is driven to rotate. At this time, the pressure roller 25
The strain ε (eg, ε = 4
%) Is generated, the tension of the belt 15 is set to zero.
In this case, the surface speed Vε of the fixing roll 1 at the nip portion is
Vε = 260 mm / s. In this state, the belt 15
When the tension is returned to the original 10 kg and the belt 15 is driven,
In this case, the speed of the belt 15 is driven to rotate at 254 mm / s.
It In addition, four stainless steel loops for stretching the belt 15
Out of the rolls 22, 23, 24, 25
Rotational force of the stainless steel roll 24 located immediately upstream
Drives the release agent supply device 9 to rotate via the gear train.
By doing so, the endless belt that comes into pressure contact with the fixing roll 1
A predetermined braking force is applied to the belt 15 and the fixing roll 1
The speed difference in the nip part with the endless belt 15
The image that is fixed in the nip area is suppressed as much as possible.
It is possible to prevent the displacement of the image.

By the way, in order to confirm the effect of the fixing device according to the present invention in the above-mentioned Japanese Patent Application No. 5-36699, the inventors of the present invention used a fixing device as shown in FIG. 2 under the conditions of the above embodiment. We made a prototype and conducted an experiment to check the occurrence state of image shift.

As a result of this experiment, the ratio a between the reduction rate a of the belt speed with respect to the driven speed and the surface strain ε of the fixing roll 1 is shown.
When expressed using / ε, 1/20 ≦ a / ε ≦ 7/10, that is, (1/20) ε ≦ a ≦ (7/10) ε, and preferably (2/10) ε ≦ a ≦ ( It is understood that the image shift can be surely prevented by setting the range of 5/10) ε. Further, it is found that 1.0 to 2.0 kg · cm is optimum as the braking torque acting on the tension roll 24.

Therefore, by setting the peripheral speed of the release agent coating roll 9e to be faster than the moving speed of the endless belt 15 by the following relational expression, a braking force capable of preventing the occurrence of image shift on the tension roll 24 can be obtained. Can be operated. Peripheral speed of release agent coating roll ≤ [(speed of endless belt) / {(1/20) ε ≤ a ≤ (7/10) ε} That is, the teeth of the gear train should satisfy the above relational expression. By setting the number and the like, it is possible to apply a predetermined braking force to the tension roll 24, and it is possible to prevent the occurrence of image shift.

In the above embodiment, the driving force of the tension roll 24 drives the release agent applying roll 9e of the release agent supplying device 9 to rotate, but the present invention is not limited to this. As the mold agent supplying device 9, it is of course possible to use a device for supplying the mold releasing agent by a web that contacts the surface of the fixing roll 1.

Further, the other driving mechanism which is rotationally driven by the driving force of the tension roll 24 is not limited to the releasing agent supplying device, but a conveying device for conveying the recording paper 51 to the fixing device, Further, a developing device used in the image forming apparatus may be used.

Further, in the above-mentioned embodiment, the case where a gear train composed of a plurality of gears is used as the driving force transmitting means for transmitting the rotational force of the tension roll to the release agent supplying device has been described. However, the present invention is not limited to this, and it is of course possible to use a churn, a timing belt, or the like to transmit the rotational force of the tension roll to another drive mechanism.

[0048]

According to the present invention having the above-described structure and operation, the recording medium can be peeled off from the surface of the fixing roll without using a peeling device, and the image shift caused by the distortion of the fixing roll can be obtained. Can prevent the occurrence of
Moreover, it is possible to provide a fixing device in which the cost is not increased and the driving force for driving the fixing roll and the like is not wasted.

[Brief description of drawings]

FIG. 1 is a front view of a drive system showing an embodiment of a fixing device according to the present invention.

FIG. 2 is a configuration diagram of an embodiment of a fixing device according to the present invention.

FIG. 3 is a sectional configuration diagram showing a drive system of the embodiment.

FIG. 4 is a front configuration diagram showing a drive system of the heat fixing roll of the embodiment.

FIG. 5 is a schematic view showing a deformed state of a fixing roll.

FIG. 6 is a block diagram showing a conventional fixing device.

FIG. 7 is an explanatory diagram showing changes in the circumferential length of the heat fixing roll.

FIG. 8 is a table showing the relationship between image shift and pressure roll load.

[Explanation of symbols]

1 heat fixing roll, 15 endless belt, 20 elastic layer, 22 to 25 tension roll, 27 drive motor, 3
0 input gear, 31 drive motor, 33 to 46 gear train, 38 heat fixing roll drive gear, 44 release agent supply drive gear.

Claims (2)

[Claims] 1. A fixing roll coated with an elastic body is wound with a part of an endless belt stretched by a plurality of rolls to form a nip portion, and an exit portion of the nip portion is provided with an inner portion of the endless belt. In a fixing device in which a pressure roll is pressed against the fixing roll from the circumferential side via the endless belt, the rotational force of the roll positioned upstream of the pressure roll among the plurality of rolls stretching the endless belt is A fixing device characterized in that a braking force is applied to the conveyance of the endless belt in the region of the pressure roll that is in pressure contact with the fixing roll by driving the other driving mechanism by utilizing the fixing mechanism. 2. A release agent supplying device for supplying a release agent to the surface of the fixing roll, the other drive mechanism being driven by utilizing the rotational force of the roll positioned upstream of the pressure roll. The fixing device according to claim 1, wherein: