JP3159125B2 - Image fixing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image fixing apparatus which heats and presses an unfixed toner image transferred onto a recording sheet and fixes the toner image on the recording sheet. The present invention relates to an improvement in an image fixing device that performs fixing by inserting a recording sheet between a built-in heating roll and an endless fixing belt that is in pressure contact with the heating roll.

[0002]

2. Description of the Related Art Conventionally, as this type of image fixing device,
One disclosed in Japanese Patent Application Laid-Open No. 5-150679 is known. As shown in FIG. 3, the apparatus includes a heating roll 1 having a halogen lamp 100 as a heater.
And an endless fixing belt 102 stretched by a plurality of rolls and disposed so as to wind around a part of the peripheral surface of the heating roll 101. Is passed between the heating roll 101 and the fixing belt 102, the toner softened by the surface temperature of the heating roll 101 penetrates between the fibers of the recording sheet 104, and the unfixed toner The image 103 is a recording sheet 104
To be firmly established.

In particular, in this image fixing apparatus, the heating roll 1
The fixing belt 102 is wound around a part of the peripheral surface of the fixing belt 101, and the recording sheet 104 is sandwiched between the heating roll 101 and the fixing belt 102 (hereinafter, such an area is referred to as a “nip area”). Is relatively long, it is possible to apply heat and pressure to the recording sheet 104 for a long time, and when the amount of unfixed toner such as a color image is large, or when passing through a fixing device. Even when the transport speed of the recording sheet 104 was high, the unfixed toner image 103 was successfully fixed to the recording sheet 104.

Further, in this image fixing apparatus, in order to prevent the recording sheet 104 having passed through the nip area from sticking to the heating roll 101 due to the adhesive force of the molten toner, the peripheral surface of the heating roll 101 is fixed to a predetermined position. The fixing belt 1 is covered with an elastic body 105 having a thickness greater than or equal to the thickness.
Pressurizing roll 1 which is in pressure contact with heating roll 101 via
06 is provided at the end of the nip area.
Of the elastic sheet 105 covering the recording sheet 10 without using any peeling device.
4 itself promotes the action of peeling off from the heating roll 101.

That is, when the elastic layer 105 is distorted, the heating roll 101 is rotating at a constant angular velocity. Therefore, as shown in FIG. Although the surface speed V ₁ of the roll 101 locally increases, the recording sheet 104
Is transported at a speed V _P slightly higher than the surface peripheral speed V ₀ of the heating roll 101 in the nip region other than the region where the pressure roll 106 is pressed (hereinafter, this speed is referred to as “reference peripheral speed of the heating roll”). Therefore, a minute slip occurs between the surface of the recording sheet 104 on which the toner is fixed and the surface of the heating roll 101 in the pressure contact area of the pressure roll 106. As a result, in this image fixing device, it is possible to prevent the phenomenon that the melted toner adheres to the heating roll 101, for example, when a large amount of toner is fixed on the recording sheet 104 as in a color image, or when the toner is tight as in thin paper. Even when the image fixing is performed on the weak recording sheet 104, the recording sheet 1 that has passed through the nip area
04 was able to be peeled off from the heating roll 101 naturally (hereinafter, such a peeling action of the recording sheet is referred to as “self-stripping action”).

On the other hand, in order to reliably exert the self-stripping function, a certain amount of distortion must be generated in the elastic layer 105 covering the heating roll 101. It is necessary to press the pressure roll 106 against the heating roll 101 with a larger force. However, this results in an increase in the frictional force acting between the recording sheet 104 and the heating roll 101. Therefore, if the pressing force is set too large, as shown in FIG. transport speed V _P becomes too substantially equal to the surface speed V ₁ of the heating roller 101 in the pressed region of the pressure roll 106, now in the beginning vicinity of the nip region the pressure roll 106 is not in contact with the recording sheet A difference occurs between the transport speed V _P of the heating roll 104 and the reference peripheral speed V ₀ of the heating roll 101.

In the vicinity of the start end of the nip area, toner 103
Has not yet penetrated sufficiently between the fibers of the recording sheet 104, and if a large deviation occurs between the transport speed of the recording sheet 104 and the reference peripheral speed of the heating roll 101, the toner image is recorded. If the pressing force of the pressure roll 16 is set to be large in order to effectively exert the above-described self-stripping operation, the fixed recording image is printed on the recording sheet 1.
There is also a problem that an image shift occurs along the transport direction of No. 04.

For this reason, Japanese Unexamined Patent Publication No. Hei.
In the image fixing device disclosed in Japanese Patent Application Laid-Open No. H10-209, as shown in FIG. 6, an auxiliary pressing roll 107 that is pressed against a heating roll 101 via a fixing belt 102 is located closer to the start end of the nip region than the pressing roll 106 is. arranged, by generating a large frictional force between the recording sheet 104 and the heating roller 101 in such a disposed position, the reference peripheral speed V ₀ which heating roller 101 the conveying speed V _P of the recording sheet 104 in the nip region , And the occurrence of the above-described image shift is prevented.

[0009] In the image fixing device disclosed in JP-A-6-250560 it is deliberately suppressed the conveying speed V _P of the recording sheet by applying a predetermined load torque to the rotation of the fixing belt, such transport thereby preventing the occurrence of image displacement as described above by approximating the velocity V _P to the reference peripheral speed V ₀ which heating roll.

On the other hand, in this type of image fixing apparatus, when the recording sheet 104 to which the unfixed toner 103 is adhered is heated by being inserted between the heating roll 101 and the fixing belt 102, the recording sheet 104 is included in the recording sheet 104. If the pressing force of the fixing belt 102 against the heating roll 101 is weak, the water vapor evaporates to generate water vapor, or the air existing between the fibers of the recording sheet 104 and between the toner particles expands thermally. It has been confirmed that a gap of about several tens of μm is generated between them, and that a defective image such as bleeding or displacement occurs in the fixed toner image.

In order to improve the pressing force of the fixing belt 102 against the heating roll 101, an image fixing apparatus disclosed in Japanese Patent Application Laid-Open No.
As shown in FIG. 2, an auxiliary pressing pad 108 having a pressing surface that slides on the back surface side of the fixing belt 102 is provided in the nip area, and the fixing belt 102 is urged to urge the auxiliary pressing pad 108. It is firmly pressed against the heating roll 101.

FIG. 8 shows the distribution of the surface speed of the heating roll 101 at this time. When the auxiliary pressing pad 108 is pressed against the heating roll 101, the heating roll 101 is distorted. surface speed is high V ₂ becomes than the reference peripheral speed V ₀ which heating roller 101, the conveying speed V _P of the recording sheet 104 is substantially equal to the V _2. While the conveying speed V _P of the recording sheet 104 in the case where this manner is pressed against the auxiliary pressure pad 108 does not match the reference peripheral speed V ₀ which heating roll 101, no image shift is not generated in the fixed image . This is because the penetration of the toner image into the recording sheet 104 is caused by the auxiliary pressing pad 1.
It is considered that this was almost completed in the pressure contact area of No. 08.

[0013]

However, when the auxiliary pressure pad 108 is used, a high-quality fixed image having no problem when plain paper is used as the recording sheet 104 can be obtained. However, when a so-called coated paper having a coating layer on the surface is used as the recording sheet 104,
For some reason, the fixed image is slightly shifted from the original fixing position in the conveying direction of the recording sheet, and a new problem occurs that a high-quality fixed image cannot be obtained.

The present invention has been made in view of such a problem, and an object of the present invention is to provide an image shift even when a so-called coated paper having a coating layer on its surface is used as a recording sheet. It is an object of the present invention to provide an image fixing device capable of obtaining a high-quality fixed image without defects.

[0015]

In order to achieve the above object, the present invention provides the following two technical means.

That is, a first technical means includes a heating roll having an elastic layer and a heat generating means and being driven to rotate at a predetermined angular velocity, a heating roll stretched by a plurality of rolls, and a heating roll. An endless fixing belt which is disposed so as to be wound around a part of the peripheral surface and forms a nip area for sandwiching the conveyed recording sheet together with the heating roll; A pressing member that presses against the heating roll via the fixing belt at the end portion and deforms the elastic layer of the heating roll, and heats the fixing member via the fixing belt at the start end side of the nip region with respect to the pressing member. An auxiliary pressurizing member that presses against the roll, the conveying speed of the recording sheet sandwiched between the heating roll and the fixing belt, and a heating roll between the pressurizing member and the auxiliary pressurizing member. It is characterized in that a surface speed substantially the same speed.

Such a technical means is derived as a result of elucidating the cause of the occurrence of image shift when using coated paper as follows.

First, since the coating layer on the surface of the coated paper to which the unfixed toner adheres has poor air permeability as compared with plain paper, the water vapor and the heated air generated as a result of heating the recording sheet as described above are used to remove the coated paper. When used, plain paper is more likely to collect between the surface of the recording sheet and the toner than when plain paper is used. Therefore, when the toner image is fixed on the coated paper, the adhesion of the toner to the recording sheet is greatly reduced, and the toner is heated more than the surface of the coated paper in the area where the auxiliary pressing pad is pressed against the heating roll. Strongly adheres to the roll surface.

On the other hand, when the shape of the peripheral surface of the heating roll is closely observed, the peripheral surface of the heating roll is deformed toward the inner diameter at the pressing position of the above-mentioned pressure roll and the auxiliary pressure pad. At the position between the pressure roll and the auxiliary pressure pad, the peripheral surface of the heating roll slightly protrudes toward the outer diameter due to the influence of pressure contact of the pressure roll and the like. Therefore, as shown in FIG. 9, the surface speed of the heating roll in a region between the pressure contact position of the pressure roll and the pressure contact position of the auxiliary pressure pad (hereinafter, this region is referred to as a “low pressure contact region”) is equal to the reference speed. It has become a slow V ₃ than the speed V _0.

[0020] Then, from these facts, the difference in speed between the surface velocity V ₃ of the heating roll in the conveying speed V _P and the low-pressure bearing region of the recording sheet is present, the heating roll in the pressed region of the auxiliary pressure pad The toner strongly adhered to the side moves from the position on the recording sheet where it should be fixed in the low pressure contact area, and is then pressed from the surface of the heating roll toward the recording sheet by the pressing force of the pressure roll. It is fixed on the recording sheet.

That is, this occurs when coated paper is used.
Image shift of the toner image in the low pressure contact area
-The image is caused by moving on the recording sheet.
In order to prevent the occurrence of an image shift, as shown in FIG.
The recording sheet conveyance speed V _PIn the low pressure welding area
Surface speed V of the heating roll_ThreeWhat should be approximately equal to
It can be concluded.

[0022] Here, the surface velocity V ₃ of the heating roll in the conveying speed V _P and the low-pressure bearing region of the recording sheet is substantially the same does not mean that these speeds are completely identical. Rate of more constant during the toner melted in pressed region of the auxiliary pressure member because it is attached to both the heating roll and the recording sheet, the conveying speed V _P of the recording sheet and the surface speed V ₃ of the heating roll As long as there is no difference, the toner does not overcome the adhesive force with the recording sheet and moves on the recording sheet, and the coat which is a problem only when there is a certain speed difference between these speeds. Image shift on paper occurs. Therefore, the speed difference as also the speed difference exists, the toner once adhered to the recording sheet is not would provide an peeled from the recording sheet between the transport velocity V _P of the recording sheet and the surface speed V ₃ of the heating roll Are included in the range of “substantially the same” in the present invention.

On the other hand, a second technical means for achieving the above object is a heating roll having an elastic body layer and a heat generating means and being driven to rotate at a predetermined angular velocity and stretched by a plurality of rolls. And an endless fixing belt that is disposed so as to be wound around a part of the peripheral surface of the heating roll and forms a nip area for sandwiching the conveyed recording sheet together with the heating roll. A pressure member that presses against the heating roll via the fixing belt at the end of the nip region, and deforms the elastic layer of the heating roll;
An auxiliary pressing member that presses against a heating roll via a fixing belt at a start end side of the nip region with respect to the pressing member, and conveys a recording sheet sandwiched between the heating roll and the fixing belt. When the speed is V _P and the reference peripheral speed of the heating roll determined by the angular speed is V ₀ ,
These speed ratio a = V _P / V ₀ is 0.990 ≦ a ≦ 1.
000.

[0024] When the present inventors actually changed variously the transporting speed V _P of the recording sheet with respect to the reference peripheral speed V ₀ which heating rolls to check the occurrence of image deviation experiments were performed, these speeds When the ratio a was within the above range, a good fixed image without image shift could be obtained. The results of such an experiment will be described later.

In the first and second technical means, the auxiliary pressurizing means may be a roll having an elastic body on its peripheral surface, that is, an auxiliary pressurized roll disclosed in Japanese Patent Application Laid-Open No. H5-150697. From the viewpoint of giving a load torque more effectively to the rotation of the fixing belt and facilitating the control of the rotation speed of the fixing belt, the auxiliary pressurizing unit may be used for the heating roll. It is preferable that the auxiliary pressing pad has a pressing surface along the peripheral surface and slides on the fixing belt.

Further, when the first and second technical means are concretely implemented, the recording sheet transport speed V
_Although it is necessary to control _P to an arbitrary speed, such control can be realized by controlling the rotation speed of the fixing belt, and more specifically, the sliding contact between the fixing belt and the auxiliary pressing member. This can be realized by increasing or decreasing the resistance or applying an arbitrary load torque to the rotation of the roll around which the fixing belt is wound.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image fixing device according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows an embodiment of an image fixing apparatus to which the present invention can be applied. As shown in the figure, this image fixing device is pressed against a heating roll 1 having a halogen lamp 11 as a heater built in around a part of the peripheral surface of the heating roll 1. 1, an endless fixing belt forming a nip area of the recording sheet 6, a pressure roll 3 which presses against the heating roll 1 from the inside of the fixing belt at the end of the nip area, and also the nip. In the area, the unfixed toner image 5 is pressed against the heating roll 1.
And an auxiliary pressure pad for promoting the fixing of the recording sheet 6 to the recording sheet 6, and the recording sheet 6 carrying the unfixed toner image 5 is inserted between the heating roll 1 and the fixing belt 2.

First, the heating roll 1 is made of a metal core 12.
Is covered with an elastic layer 13 and the core 1
2, a halogen lamp 11 having an output of 850 W is housed therein. As the core 12, an aluminum cylindrical body having an outer diameter of 47 mm and an inner diameter of 42 mm is used.
The elastic layer 13 is composed of a heat-resistant underlayer 13a and a top coat layer 13 for preventing adhesion of the melted toner.
HTV silicone rubber having a thickness of 1.5 mm and a rubber hardness of 55 ° (JIS-A)
RTV cone rubber having a thickness of 50 μm is used for the top coat layer 13b, and the heating roll 1 is formed by dip coating the top coat layer 13b on the underlayer 13a.
Is maintained in a surface state close to a mirror surface. A driving motor (not shown) is connected to the heating roll, and is driven to rotate at a predetermined angular velocity.

The surface temperature of the heating roll 1 is always detected by the temperature sensor 7, and by controlling the lighting of the halogen lamp 11 based on the detected temperature,
The surface temperature of the heating roll 1 can always be maintained at about 150 ° C. Further, dimethyl silicone oil 9 having a viscosity of 300 cst is uniformly applied to the peripheral surface of the heating roll 1 by an oil supply device 8, and the toner 5 heated and melted in the nip region is applied to the heating roll 1. Adhesion can be prevented as much as possible.

On the other hand, the fixing belt 2 has a thickness of 75 μm,
It is a polyimide film having a width of 300 mm and a circumference of 188 mm. The polyimide film is wound around the three aluminum rolls 3, 21 and 22 including the pressure roll 3 with a tension of 40 N, and rotates with the heating roll 1. It is comprised so that it may be rotated and freely rotated. Each roll is formed in a barrel shape in which the outer diameter at the center is slightly larger than the outer diameter at both ends. The maximum outer diameter of the pressure roll 3 is 23 mm, and the maximum outer diameters of the other rolls 21 and 22 are respectively. 18 mm. When the rolls 3, 21, and 22 are formed in a barrel shape in this manner, even if each roll is bent by the tension of the fixing belt 2, the peripheral surface of the fixing belt 2 becomes flat without waving, and
The fixing belt 2 can run smoothly.

The fixing belt 2 is wound around the heating roll 1 by a length corresponding to a central angle of 45 ° of the heating roll 1, and the length of the nip area along the conveying direction of the recording sheet 6 at this time. Was about 20 mm when measured.

Further, the pressure roll 3 around which the fixing belt is wound is heated by the coil spring 31 so that the recording sheet 6 having passed through the nip area exhibits a self-stripping action in which the recording sheet 6 is separated from the heating roll 1 by itself. It is biased towards the center of 1. The biasing force of the coil spring 31 is set to about 360N,
As a result, a strain toward the inner diameter of the elastic layer of the heating roll contacted by the pressure roll occurs.

On the other hand, the auxiliary pressing pad 4 is disposed adjacent to the starting end of the nip region with respect to the pressing roll 3, and the fixing pressure of the fixing belt 2 is increased in order to improve the pressing force of the fixing belt 2 against the heating roll 1. It is pressed against the heating roll 1 from the back side. The auxiliary pressing pad 4 has a thickness of 3 mm and a rubber hardness of 20 ° (JIS-JIS) on a stainless steel base material 41.
A) An elastic layer 42 made of silicone rubber is provided, and is also urged by a coil spring 43 toward the center of the heating roll 1 with a force of about 400N. Further, in order to prevent the elastic layer 42 of the auxiliary pressing pad 4 from being worn by the sliding contact with the fixing belt 2, the sliding contact surface of the auxiliary pressing pad is made of a resin sheet 44 having a low coefficient of friction such as a Teflon sheet. Coated.

The auxiliary pressure pad 4 is arranged so that its side surface is in sliding contact with the adjacent pressure roller 3, and applies a predetermined load torque to the rotation of the pressure roller 3. The rotation speed of the fixing belt 2 rotated by the heating roll 1 and the conveyance speed of the recording sheet 6 inserted between the fixing belt 2 and the heating roll 1 can be controlled. Note that the side surface of the auxiliary pressing pad 4 that is in sliding contact with the pressing roll 3 is also covered with a resin sheet 44 having a low coefficient of friction.

In the image fixing apparatus of the present embodiment configured as described above, when the recording sheet 6 is inserted through the nip area formed by pressing the heating roll 1 and the fixing belt 2 against each other, The unfixed toner image 5 carried on the recording sheet 6 is heated and pressed to be fixed on the recording sheet 6, and the pressing roll 3 is pressed against the heating roll 1 at the end of the nip area. , The recording sheet 6 having passed through the nip area can be naturally peeled off from the heating roll 1 without using a forcible peeling means such as a peeling claw.

The present inventors fix the toner image 5 on the recording sheet 6 using this image fixing device, and when the recording sheet 6 uses plain paper and coated paper, the conveying speed V _P of 6 was investigated effect on the image quality of a fixed image. Further, in order to confirm the effect of the presence of the auxiliary pressure pad 4 on the fixed image, the image quality of the fixed image was examined both when the auxiliary pressure pad 4 was omitted and when the auxiliary pressure pad 4 was provided.

[0037] Table 1 below are those showing the investigation results, the ratio of the value a conveyance velocity V _P with the reference peripheral speed V ₀ which heating roll 1 of the recording sheet 6 in the table (V _P / V ₀ A = 1.000 indicates that the recording sheet 6 is conveyed at a constant speed equal to the reference peripheral speed V ₀ of the heating roll 1. Here, the reference peripheral speed of the heating roll 1 is set to 260 mm / sec, the conveying speed V _P of the recording sheet was adjusted by changing the load torque given to the pressure roll 3.
As plain paper, J paper manufactured by Fuji Xerox Co., Ltd. was used, and as coated paper, NK high-coated paper (basis weight: 127.9 gsm) manufactured by Nippon Kasei Paper Co., Ltd. was used.

[0038] Incidentally, the conveying speed V _P of the recording sheet 6 was carried out by measuring the conveyance distance D _P of the recording sheet 6 due to the rotation of the heating roll 1. More specifically, the recording sheet 6 provided with an arbitrary measurement mark with an aqueous ink, a pencil, or the like is inserted through the fixing device, and the measurement mark offset-transferred to the recording sheet 6 by one rotation of the heating roll 1 and the original measurement mark After measuring the transport distance D _P of the recording sheet 6 from the distance, the formula of V _P = V ₀ × D _P / (πD ₀ ) is obtained from the reference peripheral speed V ₀ of the heating roll 1 and its peripheral length πD _0. Calculated using The reference peripheral speed V ₀ of the heating roll 1 was calculated from the outer diameter D ₀ and the rotation speed when the heating roll 1 was heated to a fixing temperature of about 150 ° C.

[0039]

[Table 1]

[0040] As is clear from Table 1, the auxiliary pressure pad 4 is pressed against the heating roll 1, and the ratio a of the conveying speed V _P with the reference peripheral speed V ₀ which heating roll 1 of the recording sheet is 0 When it was within the range of 0.990 ≦ a ≦ 1.000, it was possible to obtain a good fixed image with no image shift even when using not only plain paper but also coated paper. That is,
In the image fixing device of the present embodiment, the transport speed V of the recording sheet 6
_{When P} is equal to or less than the reference peripheral speed of the heating roll 1, a high-quality fixed image without image shift can be obtained.

As described with reference to FIG. 2, in the low pressure contact area between the pressure roll 3 and the auxiliary pressure pad 4,
Surface speed V ₃ of the heating roll 1 is slower than the reference peripheral speed V _0, when the experimental results shown in Table 1, the surface speed of the heating roll conveying speed V _P of the recording sheet 6 is in the low-pressure bearing region V _{As in the case of 3} , when the speed is lower than the reference peripheral speed V ₀ of the heating roll 1, a good fixed image is obtained.

In this embodiment, when controlling the conveying speed of the recording sheet 6, the auxiliary pressing pad 4 is brought into sliding contact with the pressing roll 3, and an arbitrary load torque is applied to the rotation of the pressing roll 3. As described above, a torque limiter is connected to one of the rollers 3, 21 and 22 around which the fixing belt is wound, and a load torque is applied to the rotation of the roller to thereby increase the rotation speed of the fixing belt 2 and thus the rotation speed of the fixing belt 2. It is also possible to control the transport speed of the recording sheet 6. In this case, the pressure roll 3 is in pressure contact with the back side of the fixing belt 2, and there is very little concern that the pressure roll 3 may slip with respect to the fixing belt 2. The pressure roll 3 is preferred.

[0043]

As described above, according to the image fixing apparatus of the present invention, the conveying speed of the recording sheet sandwiched between the heating roll and the fixing belt is controlled by the pressing member and the auxiliary pressing member. By setting the surface speed of the heating roll between the substantially same speed, not only when using plain paper as a recording sheet, even when using a coated paper having a coating layer on the surface, It is possible to obtain a high-quality fixed image free from image quality defects such as image shift.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an embodiment of an image fixing device to which the present invention is applied.

FIG. 2 is a diagram showing a relationship between a distribution of a surface speed of a heating roll and a conveyance speed of a recording sheet in the image fixing device of the present invention.

FIG. 3 is a schematic view showing an example of a conventional image fixing device disclosed in Japanese Patent Application Laid-Open No. 5-150679.

4 is a diagram showing a relationship between a distribution of a surface speed of a heating roll and a conveyance speed of a recording sheet in the conventional image fixing device shown in FIG.

5 is a diagram showing a relationship between a distribution of a surface speed of a heating roll and a conveying speed of a recording sheet when an image shift occurs in the conventional image fixing device shown in FIG. 3;

FIG. 6 is a schematic diagram showing another example of the conventional image fixing device disclosed in Japanese Patent Application Laid-Open No. 5-150679.

FIG. 7 is a schematic diagram showing a conventional image fixing device disclosed in Japanese Patent Application Laid-Open No. 9-34291.

8 is a diagram showing a relationship between a distribution of a surface speed of a heating roll and a conveyance speed of a recording sheet in the conventional image fixing device shown in FIG.

FIG. 9 is a diagram showing the relationship between the distribution of the surface speed of the heating roll and the conveyance speed of the recording sheet based on the estimation of the present inventors.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Heating roll, 2 ... Fixing belt, 3 ... Pressure roll, 4
... Auxiliary press pad (auxiliary press member), 5 ... Toner image, 6
… Record sheet

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 13/20 G03G 15/20

Claims (4)

(57) [Claims] 1. A heating roll having an elastic layer and heating means and driven to rotate at a predetermined angular velocity, and a heating roll stretched by a plurality of rolls and a part of a peripheral surface of the heating roll. An endless fixing belt that forms a nip area for sandwiching the conveyed recording sheet together with the heating roll, the endless fixing belt being disposed so as to be wound therearound; pressure contact with the heating roll Te, and pressure roller to deform the elastic layer of the heating roll, the auxiliary pressure member pressed against the heating roller via the fixing belt at the starting end side of the nip area than the pressure roller is composed of a, gives a predetermined load torque to the rotation of the pressure roll
This makes it possible to pinch between the heating roll and the fixing belt.
The transport speed of the inserted recording sheet is
Surface velocity of the heating roll at a position between the pressure member and
An image fixing device controlled to the same speed . 2. A heating roll having an elastic layer and having a heating means and driven to rotate at a predetermined angular velocity, a heating roll stretched by a plurality of rolls and a part of a peripheral surface of the heating roll. An endless fixing belt that forms a nip area for sandwiching the conveyed recording sheet together with the heating roll, the endless fixing belt being disposed so as to be wound therearound; pressure contact with the heating roll Te, and pressure roller to deform the elastic layer of the heating roll, the auxiliary pressure member pressed against the heating roller via the fixing belt at the starting end side of the nip area than the pressure roller is composed of a, when the conveying speed V _P of the recording sheet sandwiched between the heating roll and the fixing belt, the reference peripheral speed of the heating roll which is determined by the angular speed to V _0, the pressure roll of
By applying a predetermined load torque to the rotation, these speed ratio a = V _P / V ₀ is 0.990 ≦ a ≦ 1.0
An image fixing device controlled to be within the range of 00. 3. The image fixing device according to claim 1, wherein the auxiliary pressing member is an auxiliary pressing pad that has a pressing surface along a peripheral surface of the heating roll and slides on the fixing belt. An image fixing device, comprising: 4. The image fixing device according to claim 3, wherein:
An image fixing device, wherein a predetermined load torque is applied to the rotation of the pressure roll by sliding the auxiliary pressure pad against the pressure roll.