JPH11249481A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate irregular fixation and to prevent transfer paper from being stained due to the leakage of oil by setting the abutting force of energizing means respectively provided on the driving side and the non-driving side of a pressure roller larger on the driving side than on the non-driving side. SOLUTION: The pressure roller 2 is made rotatable by supporting both ends of a roller shaft 2a by pressuring bearings 28A and 28B and receiving members 29A and 29B. A driven gear 27 is fixed at the end of the shaft 2a on a driving gear 21 side, and meshed with the gear 21. The members 29A and 29B are respectively supported to be freely movably up and down by a driving side coil spring 14A and a non-driving side coil spring 14B respectively made to intervene between the base parts of the front and rear side plates 24a and 24b and the members 29A and 29B. In both ends of the shaft 2a of the roller 2, the springs 14A and 14B are made unbalanced and the abutting force is previously applied to the spring 14A on the side of the roller 2 where the gear 27 exists so that energizing force nearly equal to force for pressing down the gear 27 may be obtained.

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 electrophotographic image forming apparatus such as a copying machine, a printer, and a facsimile.

[0002]

2. Description of the Related Art Generally, a fixing device provided in an electrophotographic image forming apparatus includes, for example, FIG.
As shown in (B), the pressure roller 2 is pressed against the fixing roller 1, and a transfer paper having an unfixed toner image is passed through a mutual pressure contact portion (nip portion) formed, and the toner is heated and melted to fix the toner image. And a coating pad 5 for applying a releasable fixing oil is brought into contact with the fixing roller 1. The pressure roller 2 includes
The pressure roller blade 13 is applied to the fixing roller 1 from the coating pad 5 and scrapes the fixing oil from the surface to the surface of the pressure roller 2. Normally, the fixing roller 1 rotates by receiving a driving force from a motor or the like, and the pressing roller 2 rotates by rotating around the fixing roller 1. However, in order to stably transfer the transfer paper, the driving gear 21 and the driven gear 27 are provided between the fixing roller 1 and the pressure roller 2 so as to mesh with each other. A configuration of a two-roller drive system in which the drive gear 21 and the driven gear 27 transmit the pressure to the pressure roller may be used. The supporting form of the fixing roller 1 and the pressing roller 2 is, for example, as shown in FIG. 8, in a state in which both ends of the pressing roller 2 are pressed against the fixing roller 1 side by the coil springs 14, 14. The fixing drive gear 21 is fixed to the roller shaft 1a of the fixing roller 1 and the pressure driven gear 27 is fixed to the roller shaft 2a of the pressure roller 2, and the driving force is fixed by meshing these. A configuration in which the pressure roller 2 is rotated by being transmitted from the roller 1 to the pressure roller 2 is employed.

[0003]

However, in a conventional fixing device having a configuration of driving both rollers,
Coil spring 1 in which pressure roller 2 presses fixing roller 1
When the urging forces of the fixing rollers 4 and 14 are set equally at both ends of the pressure roller 2, the fixing roller 1 is driven, and the driving force is transmitted from the fixing driving gear 21 of the fixing roller 1 to the pressure driven gear 27. Then, the pressure roller 2 is rotated. At this time, as shown in FIG. 8B, a downward force of the driving force from the fixing drive gear 21 acts between the fixing drive gear 21 and the pressure driven gear 27 to fix the pressure roller 2. A force parallel to and in the opposite direction to the pressure contact direction with respect to the roller 1, that is, a force in the direction of arrow F acts on the pressure roller 2, and the pressure gear 27 is pushed down due to the pressure angle with the rotation of the fixing gear 21. And
The pressure roller 2 is pushed down on the drive shaft side in the axial direction, and the one without the pressure driven gear 27 in the axial direction of the pressure roller 2 is in a one-side-up state. When fixing is performed in this state, imbalance occurs in the mutual contact force between the peripheral surfaces of the fixing roller and the pressing roller, and the fixing paper is fixed between the fixing roller 1 and the pressing roller 2 having the unbalanced pressing force. When fixing is performed through the fixing paper, there is a possibility that uneven fixing may occur on the fixing paper. Further, if a pressure roller blade 13 that is in contact with the pressure roller 2 and scrapes the fixing oil or the like on the peripheral surface of the pressure roller 2 is provided, the pressure roller blade 13 and the pressure roller 2 And a gap is formed between the peripheral surface of the pressure roller 2 and the free end of the pressure roller blade 13, so that the fixing oil applied to the surface of the fixing roller is
The surface of the pressure roller 2 is not sufficiently scraped off by the free end of the pressure roller blade 13 on the surface of the pressure roller 2, causing oil to escape. There is a problem that the fixing paper is stained.

The invention relating to the problem of the inclination of the pressure roller 2 due to the driving force of the fixing driving gear 21 is disclosed in
Japanese Patent Application Laid-Open No. 5-297755 describes that the fixing roller and the cleaning roller are not the fixing roller and the pressure roller but the relationship between the fixing roller and the cleaning roller. In order to solve the problem that the cleaning roller is tilted when the cleaning roller is transmitted, the driving force is transmitted to the fixing roller via an elastic rotating member, thereby preventing the cleaning roller from being tilted. However, according to the present invention, there is a problem that parts processing operations such as processing of gears and the like increase, which leads to an increase in cost.

The present invention solves the above-mentioned conventional problems and has a structure in which the fixing roller and the pressure roller are directly linked with each other by a gear. The occurrence of contact failure can be prevented without increasing the number of parts, and the fixing failure of the fixing paper due to uneven fixing and the stain on the transfer paper due to missing oil have been eliminated.
It is an object of the present invention to provide a low-cost, simple fixing device.

[0006]

SUMMARY OF THE INVENTION The gist of the present invention is to provide a fixing roller in which a core is covered with an elastic member and a heating element is provided inside the fixing roller. A pressure roller that rotates in contact with the roller, an urging unit that applies an urging force to bring the pressure roller into contact with the fixing roller, an urging unit that applies an urging force to contact the fixing roller, and the fixing roller and the pressure roller And a driving force transmitting unit that transmits driving force from the fixing roller to the pressing roller, wherein the urging unit is disposed between the driving side of the pressing roller and the driving side of the pressing roller. The fixing device is provided separately for the non-driving side, and the contact force of the urging means on the driving side and the non-driving side is set larger on the driving side than on the non-driving side. .

According to a second aspect of the present invention, in the fixing device according to the first aspect, the urging means is constituted by springs provided on a driving side and a non-driving side of the pressure roller, and the pressing means is provided with a spring. The fixing device is characterized in that the difference in the contact force is set by the difference in the spring constant of the spring.

According to a third aspect of the present invention, in the fixing device of the first aspect, the urging means is swingable about a common fulcrum, and supports both ends of the pressure roller at the center thereof. And a swing member having a swing member for swinging around the fulcrum at both swing ends thereof, and a difference in abutment force of the urging means is determined by a swing member from the fulcrum of the swing device. The fixing device is set according to the difference in the distance to the fixing device.

According to a fourth aspect of the present invention, there is provided a fixing roller which covers a core metal with an elastic member and has a heating element therein, a pressing roller whose peripheral surfaces abut against the fixing roller, An urging means for applying an urging force for bringing the pressure roller into contact with the fixing roller; and a urging means provided between the fixing roller and the pressure roller, for transmitting a driving force from the fixing roller to the pressure roller. The fixing device of an image forming apparatus, comprising: a driving force transmitting unit; and a pressure roller blade that abuts on a peripheral surface of the pressure roller and removes excess material on the peripheral surface of the pressure roller. Roller blade,
A fixing device for an image forming apparatus, wherein the pressure roller and the pressure roller are integrally provided so as to be movable.

According to a fifth aspect of the present invention, in the fixing device of the image forming apparatus according to the fourth aspect, the pressure roller blade is swingably provided with respect to the pressure roller. In the fixing device of the device.

According to a sixth aspect of the present invention, in the fixing device of the image forming apparatus according to the fourth or fifth aspect, the free end of the pressure roller blade is always disposed in contact with the peripheral surface of the pressure roller. A fixing device of the image forming apparatus.

According to a seventh aspect of the present invention, there is provided a fixing roller having a core bar covered with an elastic member and having a heating element therein, a pressing roller having peripheral surfaces abutting against the fixing roller, An urging means for applying an urging force for bringing the pressure roller into contact with the fixing roller; and a urging means provided between the fixing roller and the pressure roller, for transmitting a driving force from the fixing roller to the pressure roller. The fixing device of an image forming apparatus, comprising: a driving force transmitting unit; and a pressure roller blade that abuts on a peripheral surface of the pressure roller and removes excess material on the peripheral surface of the pressure roller. The fixing device of the image forming apparatus is characterized in that the free end of the roller blade is always disposed in contact with the peripheral surface of the pressure roller.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. A color image forming device compatible with double-sided copying,
For example, a fixing device mounted on a full-color copying machine is shown in FIG.
In FIG. 1, a pressing roller 2 is disposed so as to be pressed against a fixing roller 1 pivotally supported in a main body case 12 with a predetermined pressing force. The pressure roller 2 includes a heater 4 therein. An oil application felt 5 for applying release oil to the fixing roller 1, and an oil blade 6 for regulating the amount of oil on the downstream side in the rotation direction of the roller 1, so that the main body case is in contact therewith. 12 and further in order in the rotation direction of the roller 1,
A separation claw 9 and a cleaning roller 7 for peeling the transfer paper from the fixing roller 1 are disposed on the main body case 12 side so as to abut each other. The pressure roller 2 is provided with a pressure roller blade 13 for scraping the paper powder of the transfer paper, and the cleaning roller 7 is provided with a scraper 8 to be in contact therewith. In this embodiment, an example in which the heaters 3 and 4 are incorporated in both the fixing roller 1 and the pressure roller 2 has been described. However, in the present invention, a fixing device in which the heater 3 is incorporated only inside the fixing roller 1 may be used. . In the main body case 12, a paper discharge roller pair 11 is disposed on the downstream side of the rollers 1 and 2, and a transfer paper transport unit 10 of the image forming apparatus is disposed on the upstream side of the fixing device.

The fixing roller 1 is formed by coating an elastic rubber on a core metal to form an elastic layer 1b. The outer diameter of the fixing roller 1 is 60 mm, and the thickness of the elastic layer 1b is 1 to 1.
It is set to 3 mm. On the other hand, similarly to the fixing roller 1, the pressing roller 2 is formed by coating an elastic rubber on a cored bar.
The outer diameter of the pressure roller 2 is set to 60 mm, and the thickness of the elastic layer 2b is set to 1 to 4 mm. The length of the nip N in the transfer paper transport direction by both rollers, that is, the nip width is 9.5 mm, and the fixing speed is 180 m.
m / s. Dimethyl silicone oil is used as the release oil, and the viscosity is 300 CS.
It is. In this embodiment, an oil application mechanism comprising an oil application felt 5 and an oil blade 6 allows an oil application amount of 2.0 to 10.0 mg per A4 size, that is, 1 oil.
It can be regulated to 0 mg or less. In this embodiment, the release oil is applied only to the fixing roller 1, but the oil may be applied also to the pressure roller 2. In the above configuration, the transfer paper P carrying the unfixed toner T is transported by the transfer paper transporting unit 10 from right to left in the figure and introduced into the fixing device. The transfer paper P passes through the nip N where the fixing roller 1 and the pressure roller 2 are pressed against each other, so that the unfixed toner T is fixed on the transfer paper P by heat and pressure, and is fixed by the separation claw 9. The sheet is peeled off from the roller 1 and discharged by the discharge roller pair 11.

Next, the configuration and operation of the driving system of the fixing device shown in FIG. 1 will be described with reference to FIG. In FIG. 1, a driving force input gear 20 is fixed to the right end of a roller shaft 1a of the fixing roller 1, and a fixing driving gear 21 as a driving force transmission gear is fitted and fixed to the left end of the roller shaft 1a. ing. These gears 2 are provided on the roller shaft 1a.
Adjacent to 0, 21 are provided bearing portions each including a heat insulating bush 23 and a fixing bearing 22, and are rotatably supported by the front side plate 24a and the rear side plate 24b via the bearing portions. A driving gear 30 of a driving system from a driving source (not shown) is meshed with the driving force input gear 20.

On the other hand, the pressure roller 2 has pressure roller bearings 28A, 28B and receiving members 29 at both ends of a roller shaft 2a.
A, 29B and is rotatable.
A pressure driven gear 27, which is a driving force transmission gear, is fixed to an end of the roller shaft 2a on the fixing drive gear 21 side.
The pressure driven gear 27 meshes with the fixing drive gear 21. The receiving member 29A is vertically movably supported by a coil spring 14A interposed between the receiving member 29A and the base of the front / rear side plate 24a. The receiving member 29B is vertically movably supported by a coil spring 14B interposed between the receiving member 29B and the base of the front / rear side plate 24b. That is, the pressure roller 2 is supported by the coil spring 14A on the driving gear side and the coil spring 14B on the non-driving side of the both ends of the roller so as to float. The pressure roller 2 is urged in the direction of arrow A by the coil springs 14 </ b> A and 14 </ b> B and is in pressure contact with the fixing roller 1.

The fixing drive gear 21 and the pressure driven gear 27 are both spur gears, and when they mesh with each other and rotate, the pressure roller 2 rotates in conjunction with the driving of the fixing roller 1. In this configuration, the coil springs 14A, 1
Assuming that the urging force of the pressing roller 4B is set to be equal, when the fixing roller 1 is driven, the pressure roller 2 is pushed down on the coil spring 14A side having the pressure driven gear 27 as shown in FIG. , A state where the side of the coil spring 14B which is not present is raised, that is, a one-sided state.

In the above-described configuration of this embodiment, the coil springs 14A and 14B among the two ends of the roller shaft of the pressure roller 2 are made uneven, and the force by which the pressure driven gear 27 is pushed down in relation to the pressure angle. The pressing force is applied to the coil spring 14A on the side of the pressure roller 2 where the pressure driven gear 27 is present, so that the same biasing force as that of the coil spring 14A is provided. As a result, the fixing drive gear 21 and the pressure driven gear 27 are engaged with each other, and even if a force that is pressed down due to the pressure angle of the pressure driven gear 27 acts on the pressure roller 2, a force that matches the pressing force is applied. The biasing force of the coil spring 14A, the pressure roller 2
The pressure driven gear 27 is not pushed down and the pressure roller 2 does not move upward. As a result, imbalance does not occur in the contact force between the peripheral surfaces of the fixing roller and the pressure roller, and the fixing roller 1
When fixing is to be performed through the fixing paper between the fixing roller 1 and the pressure roller 2, no imbalance occurs between the fixing roller 1 and the pressure roller 2, and there is no possibility of causing uneven fixing on the fixing paper. In addition, since the contact position of the pressure roller blade 13 with the pressure roller 2 does not change, the relative position between the pressure roller blade 13 and the pressure roller 2 does not shift, and the circumferential surface of the pressure roller 2 is not shifted. And pressure roller blade 1
3. There is no gap between the fixing roller 3 and the free end, and the fixing oil applied to the surface of the fixing roller is sufficiently scraped off at the free end of the pressure roller blade 13 to cause oil leakage or the like. There is no. In this case, as a method of making the pressing roller 2 pressurize the fixing roller 1 unevenly in the left and right directions, the urging force is determined by the spring constants of the coil springs 14A and 14B attached to both ends of the pressing roller 2. The spring constant is set to the coil spring 14A and the coil spring 14
B is different. The spring constant of the coil spring 14A and the coil spring 14B is larger for the coil spring 14A. In order to change the spring constant, the length, wire thickness, wire diameter, material, and the like of both coil springs may be set to be different between the coil springs 14A and 14B.

Another embodiment of the present invention will be described with reference to FIG. In FIG. 3, the same components as those of the above-described embodiment are denoted by the same reference numerals, and the description thereof will be omitted. In FIG. 3, one end 1
51A and 152A are pivotally supported by a common fulcrum 15a toward the body case (not shown), and the other ends 151B and 152A are pivotally supported.
152B are two arm members 151, 1 attached to the main body case side via coil springs 114A, 114B.
52, both ends 2A and 2B of the pressure roller 2 are supported
In a configuration in which the arm member 15 is movable in the direction of arrow B, the coil springs 114A and 114B are of a conventional type.
That is, the same one is used as it is, but the coil spring 114 is moved from the fulcrum 15a on the arm members 151 and 152.
A difference in urging force is set according to the magnitude of the distance to the position where A, 114B is attached. That is, the pressure driven gear 2
The same distance L on the arm member 15A on the side where
1 is the arm member 15 on the side without the pressure driven gear 27.
B1 is larger than the same distance L2 on B, and L1> L2.
As a result, the force of the arm member 151 in the direction of arrow B becomes greater than the force of the arm member 152 in the direction of arrow B, so that the fixing drive gear 21 and the pressure driven gear 27 mesh with each other, and the pressure of the pressure driven gear 27 Even if a force depressed due to the angular relationship acts on the pressure roller 2, the arm member 151 has a biasing force corresponding to the depressed force.
The pressure driven gear 27 is not pushed down and the pressure roller 2 does not move upward. As a result, there is no imbalance in the abutting force of the peripheral surfaces of the fixing roller 1 and the pressing roller 2, and when fixing is to be performed between the fixing roller 1 and the pressing roller 2 through the fixing paper, There is no imbalance between the fixing roller 1 and the pressure roller 2, and there is no possibility of causing uneven fixing on the fixing paper. In addition, since the contact position of the pressure roller blade 13 with the pressure roller 2 does not change, the relative position between the pressure roller blade 13 and the pressure roller 2 does not shift, and No gap is created between the pressure roller blade 13 and the free end of the pressure roller blade 13, and the free end of the pressure roller blade 13 abuts on the surface of the pressure roller 2 evenly in the axial direction. The fixing oil is sufficiently scraped off at the free end of the pressure roller blade 13,
There is no oil leakage.

Regarding the arm members 151 and 152,
In the above-described embodiment, as a means for changing the force for moving the pressure roller 2 in the direction of arrow B, an equivalent coil spring is used, and a means for providing the same is employed. In the present invention, the provided position is not changed. The arm member 151 may have a large spring constant, and the arm member 152 may have a small spring constant. In this embodiment, a single arm member 15 is provided with two holes, or dents, for hooking the coil spring 14 at a distance L1 from the fulcrum 15a and at a distance L2 from the fulcrum 15a. It can be used to reduce the number of parts.

Next, another embodiment will be described with reference to FIG. In FIG. 4, the same configuration as the above-described embodiment is
The same reference numerals are given and the description is omitted. In the figure,
The pressure roller blade 131 has an S-shaped cross section rotatable about a shaft 131d provided between the pair of blade support members 16A and 16B, and a blade member 132 formed of an elastic body at a free end 131a. Is fixed to the other end portion 131c of the blade member and the blade supporting members 16A and 16B.
The coil springs 17, 17
As a result, the tip of the blade is urged in the direction of arrow C and is in contact with the pressure roller 2. Blade support member 16A,
The base of 16B is the two ends 2 of the roller shaft of the pressure roller 2.
A and 2B are rotatably supported. In this embodiment, the pressure roller 2 at the other end of the pressure roller blade 131 is used.
Are provided on both sides, but in the present invention, the coil springs 17 are provided on either one, and the other may not be provided. Thereby, as shown in FIG. 5, when the fixing roller 1 is driven, the pressure roller 2
Even if it is in a so-called one-sided state in which the side with the pressure roller is not pushed down, the pressure roller blade 131 moves while being supported integrally with the pressure roller 2, The state of contact with the peripheral surface of the roller 2 can be maintained, and the contact position of the blade 132 with the pressure roller 2 does not change. There is no gap in
The free end of the pressure roller blade 131 uniformly contacts the surface of the pressure roller 2 in the axial direction, and the fixing oil on the surface of the pressure roller 2 is sufficiently scraped off by the free end of the pressure roller blade 131. There is no oil leakage. In this embodiment, the pressure roller blade 131 has an S-shaped cross section rotatable about a shaft 131d, and a blade member 132 formed of an elastic body at a free end 131a.
In the present invention, a scraping blade (not shown) made of an elastic material such as rubber is directly fixed to the blade supporting members 16A and 16B, and an appropriate A configuration for obtaining a pressing force against the pressure roller 2 may be used. Note that FIG. 5 and FIG. 8B shown in the related art show an upwardly raised state of the pressure roller 2 using an exaggerated expression for easy understanding.

FIG. 6 shows another embodiment of the pressure roller blade. In FIG. 6, the same components as those of the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted. As shown in FIG. 6, the pressure roller blade 231 includes a U-shaped support member 231a and shaft members 233 and 234, and the support member 231a has bifurcated ends 231 thereof.
aA, 231aB at both ends 2A, 2B of the roller shaft 2a.
And a blade 235 made of an elastic body is fixed below the central portion 231F. Roller shaft 2
Shaft members 233 and 234 are rotatably provided at both ends 2A and 2B of the coil spring a, and tension coil springs 117 and 11 are provided between the shaft members 233 and 234 and the support member 231a.
7 is applied to the support member 231a so as to be movable in the direction of the roller shaft 2a by the tension coil springs 117 and 117. As a result, the tip of the blade 18a always contacts the peripheral surface of the pressure roller 2.
Also in this case, the pressure roller blade 231 moves while being supported integrally with the pressure roller 2,
The tip of the pressure roller 31 can be kept in contact with the peripheral surface of the pressure roller 2, and the contact position of the pressure roller blade 13 with the pressure roller 2 does not change. There is no gap between the free end of the pressure roller blade 13 and the free end of the pressure roller blade 231 evenly abuts the surface of the pressure roller 2 in the axial direction. Is sufficiently scraped off at the free end of the pressure roller blade 231, and the fixing oil applied to the surface of the fixing roller is sufficiently scraped off at the free end of the pressure roller blade 13, causing oil leakage and the like. Never do.

Further, another embodiment of the pressure roller blade will be described with reference to FIG. In FIG. 7, the same components as those of the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted. In FIG. 7, a first blade support lever 331 is rotatably provided on the front side plate 24a, and a second blade support lever 332 is provided rotatably on the rear side plate 24b. The first blade support lever 331 and the second blade Support lever 33
A blade 335 made of an elastic material is fixed to the two free ends 331a and 332b. The other end portions 331b and 332b of the first blade support lever 331 and the second blade support lever 332 have tension coil springs 337,
The first blade support lever 331 and the second blade support lever 332 are given rotation behavior in the direction of arrow E by the tension coil springs 337 and 337. First blade support lever 33
1 and the second blade support lever 332 are given a rotation behavior in the direction of arrow E, so that the blade 335
Presses against the peripheral surface of the pressure roller 2. The first blade support lever 331 and the second blade support lever 332 can rotate independently of each other, and since the blade 335 is made of a flexible elastic body, the pressure roller 2 Even if it is in the so-called one-sided state, the one with the
5, the free end is moved along the peripheral surface of the pressure roller 2,
There is no gap between the pressure roller 2 and the peripheral surface.

[0024]

As described above, according to the first aspect, the urging means is provided on the driving side and the non-driving side of the pressure roller, and the urging means on the driving side and the non-driving side is provided. Since the contact force is set to be greater on the drive side than on the non-drive side, at low cost, the urging force of the urging means against the pressure roller and the force for pushing it down are balanced, and the fixing roller and the pressure roller The pressure-contact portions are evenly abutted in the axial direction, so that there is no gap between them, no uneven fixing occurs, and the fixing property can be improved. Further, since the pressure roller blade is brought into close contact with the pressure roller, it is possible to prevent the transfer paper from being stained without causing oil leakage.

According to the second aspect, the urging means for applying an urging force to the pressure roller is a spring attached to both ends of the pressure roller, and the driving force transmission gear is moved in the axial direction of the pressure roller. Since the spring constant is set so that the biasing force on the holding side is larger than the biasing force on the opposite side, it is possible to reduce unevenness of the fixing and oil removal at low cost without making a significant change to the conventional fixing device. Of the transfer paper can be prevented, and the fixing property can be improved.

According to the third aspect, the biasing means for biasing the pressure roller is swingable about a common fulcrum, and supports both ends of the pressure roller at the center thereof. A swing device having a swing member for swinging about the fulcrum at both swing ends is provided, and a difference in abutment force of the urging means is determined by a difference between a fulcrum of the swing device and a swing member. Since the distance is set differently, it is possible to prevent the occurrence of uneven fixing and the stain on the transfer paper due to oil loss at low cost without significantly changing the conventional fixing device, and improve the fixing performance. Can be done.

According to the fourth aspect, since the pressure roller blade is integrally provided movably with the pressure roller, a gap is generated between the pressure roller blade and the peripheral surface of the pressure roller. Without this, it is possible to prevent the transfer paper from being stained due to oil loss.

According to the fifth aspect, since the pressure roller blade is provided so as to be able to swing with respect to the pressure roller, even if the pressure roller is inclined, the pressure roller blade and the pressure roller can be properly adjusted. The contact position can be maintained, without making significant changes to the conventional fixing device, at low cost, without generating a gap between the peripheral surface of the pressure roller blade and the pressure roller, The transfer paper can be prevented from being stained due to oil loss, and the fixability can be improved.

According to the sixth aspect, the free end of the pressure roller blade is always disposed in contact with the peripheral surface of the pressure roller, so that the pressure roller blade is moved with respect to the blade support member. Since the pressure roller is movable in the diameter direction of the pressure roller and is attached while being urged in the contact direction, even if the pressure roller is inclined, an appropriate contact position between the pressure roller blade and the pressure roller can be achieved. Can be maintained, without significant changes to the conventional fixing device, at low cost, without causing a gap between the peripheral surface of the pressure roller blade and the pressure roller, The transfer paper can be prevented from being stained, and the fixability can be improved.

According to the seventh aspect, since the free end of the pressure roller blade is arranged so as to be always in contact with the peripheral surface of the pressure roller, the conventional fixing device is not greatly changed. It is possible to prevent the transfer paper from being stained due to oil leakage and to improve the fixing property at low cost without generating a gap between the pressure roller blade and the peripheral surface of the pressure roller. .

[Brief description of the drawings]

FIG. 1 is a sectional configuration diagram of a fixing device according to an embodiment of the present invention.

FIG. 2 is a side sectional view showing a fixing roller, a pressure roller and a driving mechanism of the fixing device according to the embodiment of the present invention.

FIG. 3 is a perspective view illustrating a positional relationship between an arm member and a coil spring according to another embodiment of the present invention.

FIG. 4 is a perspective view of a pressure roller and a pressure roller blade showing still another embodiment of the present invention.

FIG. 5 is an explanatory diagram showing the operation of FIG. 4;

FIG. 6 is a perspective view of a pressure roller and a pressure roller blade showing still another embodiment of the present invention.

FIG. 7 is a perspective view of a pressure roller and a pressure roller blade showing still another embodiment of the present invention.

FIG. 8 is an explanatory diagram of a conventional fixing device.

[Explanation of symbols]

 Reference Signs List 1 fixing roller 2 pressure roller 14A, drive side coil spring 14B, non-drive side coil spring 16A, 16B blade support member 21 drive gear 27 driven gear 132 blade member 151 drive side arm member 152 non-drive side arm member 231a Support member 235,335 Blade 331 First blade support lever 332 Second blade support lever

Claims (7)

[Claims] A fixing roller having a heating element inside the core roller, a pressure roller rotating in contact with the fixing roller, and a pressure roller contacting the fixing roller. An urging means for applying an urging force to be brought into contact with the urging means; an urging means for applying an urging force to be brought into contact with the urging means; and a driving force provided between the fixing roller and the pressure roller. In the fixing device of the image forming apparatus having a driving force transmitting means for transmitting, the urging means is provided separately on a driving side and a non-driving side of the pressure roller, and the driving side and the non-driving side Wherein the contact force of the urging means is set to be larger on the drive side than on the non-drive side. 2. The fixing device according to claim 1, wherein said urging means comprises a spring provided on a driving side and a non-driving side of said pressure roller. A fixing device, wherein the setting is made based on a difference in spring constant of the spring. 3. A fixing device according to claim 1, wherein said urging means is swingable about a common fulcrum, and supports both ends of said pressure roller at the center thereof. A swinging device having a rotating member at the moving end for rotating around the fulcrum is used, and the difference in the contact force of the urging means is determined by the difference in the distance from the fulcrum of the swinging device to the rotating member. A fixing device characterized by being set by: 4. A fixing roller having a core covered with an elastic member and having a heating element therein, a pressure roller having a peripheral surface in contact with the fixing roller, and An urging means for applying an urging force to be brought into contact with the roller; a driving force transmitting means provided between the fixing roller and the pressure roller, for transmitting a driving force from the fixing roller to the pressure roller; A pressure roller blade that abuts on a peripheral surface of the pressure roller and removes excess material on the peripheral surface of the pressure roller, wherein the pressure roller blade is A fixing device for an image forming apparatus, wherein a pressure roller and a fixing roller are integrally provided so as to be movable. 5. A fixing device for an image forming apparatus according to claim 4, wherein said pressure roller blade is provided so as to be swingable with respect to said pressure roller. 6. A fixing device for an image forming apparatus according to claim 4, wherein a free end of said pressure roller blade is always in contact with a peripheral surface of said pressure roller. Fixing device of an image forming apparatus. 7. A fixing roller having a core covered with an elastic member and having a heating element therein, a pressure roller having peripheral surfaces abutting against the fixing roller, and fixing the pressure roller to the fixing roller. An urging means for applying an urging force to be brought into contact with the roller; a driving force transmitting means provided between the fixing roller and the pressure roller, for transmitting a driving force from the fixing roller to the pressure roller; A pressure roller blade that abuts on a peripheral surface of the pressure roller and removes surplus material on the peripheral surface of the pressure roller; and a free end of the pressure roller blade. A fixing unit that is always in contact with the peripheral surface of the pressure roller.