JP2000097298A - Side-shift preventing device of endless film, film type heating device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inhibit a rapid displacement of a film supporting member end and use a side-shift detection member having a coarse surface roughness by displacing a film tensile force corresponding to the position displacement of the end of the film supporting member by a variable tensile force means. SOLUTION: A tensile force is imparted to an endless film 1 wound around a driving roller 3 and a heater 4 by a pressing spring 8 as a variable tensile force means. A contact pressure between a ring 6 and the endless film 1 by a compression of the pressing spring 8 is varied corresponding to a displacement of a driven roller 3 end. Thereby, even if a surface roughness of the ring 6 is made larger, the rapid displacement of the end of the film supporting member can be inhibited and a side-shift detection member having a coarse surface roughness can be used by setting a cam surface shape of a cam 30, a spring constant of the pressing spring 8 and a spring constant of a tension spring 10 so as to cancel out a rapid variation of a rotation torque T of the ring 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has an endless film (or an endless belt member) that is stretched between at least two or more support shaft members and rotates, and the endless film is rotated during the rotation of the endless film. A mechanism for preventing a shift along a film support member in a film width direction (film rotation axis direction) crossing (orthogonal to) the film rotation direction (a shift movement control device mechanism;
The present invention relates to an endless film deviation prevention device such as a deviation movement control mechanism), a film type heating device provided with the endless film deviation prevention device, and an image forming apparatus.

[0002]

2. Description of the Related Art As an apparatus having an endless film which is stretched across at least two or more support shaft members, there is, for example, a film type heating apparatus, for example, as disclosed in JP-A-63-313182. It is known.

FIG. 4 shows an example of this film type heating apparatus. A horizontally long heating element 4 whose longitudinal direction is perpendicular to the paper surface is, for example, a pattern in which a resistance heating element pattern is printed on the surface of a ceramic substrate. The heater has a low heat capacity and is fixed to the support stay 4b via a heater holder 4a made of a heat insulating material.

The driving roller 2 and the driven roller (tension roller) 3 are disposed substantially parallel to the heating element 4 with their respective shaft portions rotatably held between bearings (not shown). The drive roller 2 has a diameter of, for example, 10 to 30 mm, has a heat-resistant rubber layer on its surface, and includes a drive source M of a rotary drive system.

The above-mentioned drive roller 2, driven roller 3, and heating element 4 function as shaft members. The endless film 1 suspended between these three members is, for example, a heat-resistant resin film such as polyimide. It has a thickness of about 80 μm, has a fluorine-based release layer of 5 to 20 μm on the outer peripheral surface, and a circumference of about 60 to 300 mm. A pressure roller 5 made of silicon rubber or the like, which is pressed against the heating body 4 with the endless film 1 interposed therebetween, is provided.

When the drive roller 2 is driven to rotate clockwise as indicated by an arrow in the figure, the driving force is transmitted to the endless film by the brushing force of the outer peripheral surface of the drive roller and the inner peripheral surface of the endless film 1. The endless film 1 rotates between the driving roller 2, the driven roller 3, and the heating member 4 in a clockwise direction indicated by an arrow in FIG. In this case, since the endless film 1 is pressed against the heating element 4 by the pressure roller 5, the inner surface rotates while sliding in close contact with the surface of the heating element 4. The pressure roller 5 is an endless film 1
It rotates following the rotation of.

In a state where the endless film 1 is driven to rotate and the heating element 4 generates heat by energization and is controlled to a predetermined temperature, an endless film of a pressure contact portion (heating section) N between the heating element 4 and the pressure roller 5 is provided. The recording material P is introduced between the roller 1 and the pressure roller 5, the recording material P is pinched and conveyed together with the endless film 1, and is heated by the heat of the heating element 4 via the endless film 1. Heat treatment.

Such a film-type heating apparatus is used, for example, in an image forming apparatus such as a copying machine, a laser beam printer (LBP), or an electrostatic printer to form a recording material P on which an unfixed toner image to be fixed is formed and carried. The present invention can be effectively used as a unit or a device for heating a recording material widely, such as an image heating fixing device, a device for heating a recording material P carrying an image to improve the surface property, and a device for temporarily attaching.

A heat roller type heating device, which has been widely used as an image heat fixing device in an image forming apparatus than before, has a large heat capacity of the heat roller. Therefore, it is necessary to raise the heat roller to a predetermined fixing temperature. It takes a long wait time, and power must be supplied so that the startup temperature can be maintained even when the image forming apparatus is not used (during standby).

On the other hand, in the above-mentioned film type heating apparatus, both the heating element 4 and the endless film 1 can use extremely small heat capacities, and the temperature rises quickly, so that the image forming apparatus is not suitable for use. Even if the temperature of the fixing device is the same as the room temperature during standby,
The heating element 4 and the endless film 1 immediately rise to a predetermined fixable temperature due to the power supply to the heater.

That is, it has excellent quick start property,
The power consumption of the fixing device at the time of standby can be reduced to zero, power can be saved, the wait time can be reduced, and the temperature inside the image forming apparatus can be suppressed.

However, like this film type heating device or image heating and fixing device, an endless film 1 which is suspended between at least two or more members, that is, a driving roller 2, a driven roller 3, and a heating member 4, and rotates. Is more or less naturally shifted along the driving roller 2, the driven roller 3, and the heating element 4 toward one end or the other end in the film width direction orthogonal to the film rotation direction. ).

The cause of the positional deviation due to the one-sided movement of the film includes the parallelism and the twist between the above-mentioned shaft members around which the endless film 1 is hung. There is a limit, and it is difficult to prevent the above-mentioned movement toward the film only by improving the accuracy.

As one of the means for preventing or controlling the shift of the endless film 1, for example, as shown in Japanese Patent Application Laid-Open No. 4-121337, a support member for supporting the endless film 1 is suspended. One end is provided with a film shift detection ring to which the end of the endless film is attached, and the rotation of the endless film 1 is changed according to the shift of the end of the film with the shift detection ring in accordance with the shift width of the endless film. Then, the rotational force (rotation torque) due to the sliding movement force of the endless film acting on the deviation detection ring is converted into linear motion, and the film support member is relatively moved to a balanced position to thereby control the deviation of the film. There is something to control.

FIGS. 4 and 5 show a film type heating device to which the film deviation control device is applied, and a driven roller 3, which is one of the film support members, has a shaft portion on the back end side not shown. And the shaft portion 3a on the front end side is rotatably supported by the swing bearing 7.

The oscillating bearing 7 is used for the endless film 1.
The urging roller 8 is urged by a pressing spring 8 to bias the driven roller 3 in the direction in which the swing roller 7 is extended, and is urged by a tension spring 10 to bias the swing bearing 7 in the lifting direction.

A ring 6 as a film shift detecting member is rotatably and concentrically fitted on the shaft portion 3a of the driven roller 3 on the side of the swing bearing 7. The end face 6a of the ring 6 on the far side (the side near the center in the width direction crossing the running direction of the endless film 1) is almost in contact with the end face on the front end side of the driven roller 3, and is substantially the same as the driven roller 3. Of diameter.

The front end face of the ring 6 is provided with a cylindrical control belt take-up portion 11 having an outer diameter smaller than the diameter of the driven roller 3 integrally with the ring, concentrically with the shaft 3a. The ring 6 has an edge portion on the front end side of the endless film 1 suspended around the driven roller 3.

One end 9a is fixed to the outer surface of the control belt winding section 11, and the other end 9b is locked to a stationary locking section 21 (for example, a side plate (not shown)) below the control belt winding section 11. Thus, a control belt 9 is provided. The control belt 9 is a member having flexibility and small tensile elongation. Further, the winding section 11 of the control belt 9
Is a direction in which the ring 6 is wound around the winding unit 11 by a rotational torque caused by sliding friction of the ring 6 with the endless film 1.

Next, the operation will be described.

When the driving source M is biased and the driving roller 2 rotates, when the endless film 1 runs in the direction of the arrow in FIG.
And the endless film 1 slides.

(1) In the process of rotating the endless film 1, the endless film 1 moves toward the back end direction B in the film width direction, and the end width of the endless film 1 with respect to the ring 6 at the front end side (the amount of the end) When W becomes smaller, the frictional force between the endless film 1 and the ring 6 becomes smaller, and the rotational torque T acting on the ring 6 becomes smaller.
Also decreases.

For this reason, the tension of the tension spring 1 is larger than the control belt winding force of the winding unit 11 by the rotation torque T.
0, the force F by which the front end side of the driven roller 3 is pulled up.
Becomes larger, the front end side of the driven roller 3 is displaced upward U with the swivel bearing on the rear end side as a fulcrum, and the driven roller 3 is moved forward and backward with respect to the axis of the drive roller 2 and the heating element 4 by this displacement. Twist occurs.

As a result, the peripheral length of the endless film 1 to be wound around the driving roller 2, the driven roller 3, and the heating element 4 is increased on the front end side of the driven roller 3, and the endless film 1 is moved on the rear end side. Move in direction B. Then, along with this movement, the force of moving the endless film 1 toward the far end decreases, and finally becomes zero. However, since the endless film 1 goes too far to the far end side due to inertia, a force to return to the near end side of the endless film 1 is generated,
The endless film 1 returns to the front end side direction A in the film width direction opposite to the back end direction B in the film width direction.

When the endless film 1 moves excessively to the far end, even if the swing bearing 7 hits the upper limit stopper member 13 shown by a solid line in FIG. Return to and move on.

(2) As the endless film 1 returns in the direction A toward the front end, the width W of the endless film 1 with respect to the ring 6 increases, and the frictional force between the endless film 1 and the ring 6 increases. Therefore, the rotational torque T acting on the ring 6 also increases.

Due to the increase of the rotation torque T, the control belt winding force of the winding unit 11 increases, and the pulling force of the driven roller 3 on the front end side by the control belt winding of the winding unit 11 increases. Pulling force F
When it becomes larger, the control belt 9 is wound around the winding unit 11, so that the front end side of the driven roller 3 is pulled down around the universal bearing on the back end side against the tension spring 10 to lower the lower LW. Displaced to.

Due to the displacement of the driven roller 3 to the lower side LW, the driven roller 3 is twisted at the front of the axis of the driving roller 2 and the heating element 4 in a direction opposite to that in the state shown in FIG. As a result, the peripheral length of the endless film 1 to be wound around the driving roller 2, the driven roller 3, and the heating element 4 becomes shorter at the front end side of the driven roller 3, and the endless film 1 moves to the front end side. The force of moving the endless film 1 toward the front end gradually decreases, and finally becomes zero. However, since the endless film 1 goes too far to the front end side due to inertia, a force toward the back end side of the endless film 1 is generated, and the endless film 1 is in a direction opposite to the above-described front end side direction A in the film width direction. It returns and moves in the back end direction B in the film width direction.

When the endless film 1 moves excessively to the front end side, even if the swing bearing 7 hits the lower limit stopper member 12 shown by a solid line in FIG. Move toward.

That is, the ring 6 is the endless film 1
The rotation torque T is applied due to the frictional force with the ring 6, and the rotation torque T changes depending on the size of the film width W applied to the ring 6. The larger the film width W is, the larger the rotation torque T of the ring 6 becomes. The force of the take-up section 11 to wind up the control belt 9 increases. Then, the force for winding up the control belt 9 and the lifting force F of the tension spring 10
, The front side of the driven roller 3 is up and down UL
W, the direction A / B of the rotation of the rotating film 1
Is controlled.

In the process of displacing the driven roller 3 toward the upper end U or the lower LW on the front end side, the tension spring 10
And the pulling-down force F on the front end side of the driven roller due to the force of winding the control belt 9 of the winding unit 11 sometimes balances with each other. At this time, the driven roller 3 moves toward the endless film 1 The endless film 1 comes to a standstill at the balance position, and the endless film 1 stops moving and rotates at a certain position.

[0032]

As described above, the conventional endless film shift control device performs automatic balance shift control using the endless film shift movement, but has the following problems. Was.

Shift detection ring 6 and endless film 1
If the sliding resistance (frictional force) of the driven roller 3 is too large,
Becomes too sensitive, and the stability of the shift control is lacking. Therefore, it is necessary to set the frictional force small to some extent. As a method of reducing the frictional force, a method of reducing the contact pressure between the shift detection ring 6 and the endless film 1 and a method of reducing the friction coefficient of the shift detection ring 6 are considered. This is not preferable because the rotational conveyance force of the endless film 1 is also reduced.

Therefore, it is easy and general to change the surface roughness by reducing the friction coefficient of the deviation detecting ring 6. However, when the surface roughness is reduced, the surface roughness tends to change due to abrasion of the deviation detecting ring 6 and the endless film 1, and the like. The slippage caused by the separation of grease applied to the sliding part or the contact part between the endless film 1 and the film spindle member, and the incorporation of wear products into the sliding surface between the endless film 1 and the shift detection ring 6 Although the surface of the detection ring 6 is contaminated, the frictional force between the deviation detection ring 6 and the endless film 1 is reduced even though the amount of engagement of the endless film 1 on the deviation detection ring 6 does not change, and the end of the driven roller May be displaced and the endless film 1 may be shifted toward an unnecessary direction, and there is a problem in the stability of the shift control function.

The present invention has been made in order to solve the above-mentioned problems. Even when a film deviation detection ring having a high coefficient of friction is used, the driven roller does not react excessively, and the environment, aging, etc. It is an object of the present invention to obtain an endless film shift control device which is hardly affected by the above.

Further, a film-type heating device capable of smoothly transporting a recording material and performing high-precision heating by using the endless-film shift control device, and a high-quality image using the film-type heating device. It is an object of the present invention to provide an image forming apparatus capable of performing formation.

[0037]

According to the present invention, there is provided a film shift control device, a film type heat fixing device, and an image forming apparatus having the following constitutions.

(1) an endless film which is wound between at least two or more film support members and rotates;
The end of the endless film is rotatably supported at one end of at least one film support member, and the end of the endless film is connected to the film shift detection member. The frictional force between the film shift detection member and the endless film When a rotational torque is applied to the film shift detecting member, the rotation of the film shift detecting member is converted into a linear motion to displace the end of the film support member in a predetermined direction. And a tension varying means for changing a tension of the endless film in accordance with a positional displacement of an end of the film support member.

(2) A spring according to claim 1, wherein a spring is used as a means for generating tension of the endless film, and a cam is used as means for changing the film tension in accordance with the displacement of the end of the film support member. Endless film shift prevention device.

(3) The bearing at one end of the film support member is supported by a rotatable arm so as to be movable on a line connecting the arm rotation center and the film support shaft center, and the cam for the cam is supported. A spring receiving portion having a surface sliding member, and a spring member for urging the bearing between the spring receiving portion and the one end bearing so as to stretch and hang the endless film; 3. The device according to claim 2, wherein the cam surface sliding member is provided at a position close to the center of rotation of the arm.

(4) A fixed heating element, a heat-resistant endless film that is hung and rotated between the heating element and at least one film support member, and a recording material via the endless film. 4. A pressure member for holding and transporting the heating body in close contact with the heating body, and the device for preventing the endless film from shifting according to claim 1, wherein the heat of the heating body is transferred to the endless film. 5. A film type heating apparatus, wherein the image is applied to the recording material via a film to heat and fix an image on the recording material.

(5) In an image forming apparatus having an image forming means for forming and carrying an unfixed image on a recording material and a fixing means for heating and fixing the unfixed image formed and carried on the recording material, the fixing means comprises Item 6. An image forming apparatus, which is the film type heating apparatus according to Item 5.

[0043]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings.

Embodiment 1 FIG. 1 is a perspective view showing a configuration of a film-type heating device to which an endless film deviation control device according to Embodiment 1 of the present invention is applied. The endless film deviation prevention device is the same as that of FIG. 4 are the same as those in FIG. 4, the same members are denoted by the same reference numerals, and redundant description will be omitted.

One end of the driven roller 3 is rotatably supported by a swing bearing 7, and applies a certain tension to the endless film 1 suspended with the driving roller 3 and the heating device 4 by a pressing spring 8. I have. The other end of the pressing spring 8 opposite to the one end acting on the swing bearing 7 is
A spring receiver 31 is attached. This spring receiver 31
Is held by an arm 32 coupled to a side plate (not shown) or the like so as to be rotatable about a shaft 32a similarly to the swing bearing 7, and the spring bearing 31 and the swing bearing 7 are both pressed pressure springs 8 Are held movably in the direction of expansion and contraction. Spring support 3
Numeral 1 has a protruding shaft 31a and is movably connected to a cam surface (elongated hole) 30a of a positioning cam 30 which is immovably connected to a side plate (not shown) or the like.

Next, the operation will be described.

When the driving roller 2 is rotated by the driving force transmitted from the driving source, when the endless film 1 runs in the direction of the arrow in FIG. 1, the driven roller 3 is driven to wind, and the ring 6 and the endless film 1 slide. Move.

At this time, due to some factor, the endless film 1 moves toward the back end direction B in the film width direction, and the width (hanging amount) W of the endless film 1 with respect to the ring 6 on the front end side decreases. Sometimes, the frictional force between the endless film 1 and the ring 6 becomes small,
The rotational torque T acting on the ring 6 also decreases.

Therefore, the force F by which the front end side of the driven roller 3 is pulled up by the tension spring 10 is larger than the winding force of the control belt 9 of the winding unit 11 by the rotation torque T, and the driven roller 3 Shaft 3 on the front end side
The arm 32 having the rotation center 2a is lifted.

Similarly, both the spring bearing 31 and the swing bearing 7 are movable in the direction of expansion and contraction of the pressing spring 8 by the arm 32.
Oscillating bearing 7 is driven by drive roller 2
And the heating element 4 draws an elliptical arc centered on the middle point, and the spring receiver 31 draws an arc-shaped trajectory centered on the shaft 32a and tries to displace upward.

At this time, since the positioning cam 30 is immovably connected, the position of the spring receiver 31 is regulated by the cam surface (long hole) 30a of the positioning cam 30, so that the spring receiver 31 is centered on the shaft 32a. Displaces without drawing a locus of concentric arcs.

When the endless film moves in the direction B, the distance between the shaft 32a and the protruding shaft 31a in FIG. 1 increases and displaces because the arm 32 is lifted upward. That is, while the distance between the spring bearing 31 and the oscillating bearing 7 decreases, the oscillating bearing 7 is displaced by drawing an elliptical arc centered on the midpoint of the driving roller 2 and the heating element 4. Is pushed upward, the pressing spring 8 is compressed, and the contact pressure between the ring 6 and the endless film 1 increases.

On the other hand, when the endless film 1 moves toward the front end side direction A in the film width direction and the width W (hung amount) of the endless film 1 with respect to the ring 6 on the front end side increases, the endless film 1 and the endless film 1 move together. The frictional force of the ring 6 increases, and the rotational torque T acting on the ring 6 also increases.

Therefore, the winding force of the control belt 9 of the winding unit 11 by the rotation torque T is reduced by the tension spring 1.
0, the force F by which the front end side of the driven roller 3 is pulled up.
And the shaft 32 on the front end side of the driven roller 3
The arm 32 whose rotation center is a is pulled down.

Similarly, since the spring bearing 31 and the oscillating bearing 7 are both held by the arm 32 so as to be movable in the direction of expansion and contraction of the pressing spring 8, the oscillating bearing 7 is provided between the drive roller 2 and the heating element 4. An elliptical arc centered on a point is drawn, and the spring receiver 31 attempts to displace downward by drawing an arc-shaped trajectory centered on the shaft 32a.

At this time, since the positioning cam 30 is immovably connected, the position of the spring receiver 31 is regulated by the cam surface (elongated hole) 30a of the positioning cam 30, and the locus of a concentric arc centered on the shaft 32a is drawn. Displaced. When the endless film moves in the direction A, the distance between the shaft 32a and the protruding shaft 31a in FIG. 1 decreases and displaces because the arm 32 is pulled down. That is, while the distance between the spring bearing 31 and the oscillating bearing 7 increases, the oscillating bearing 7 is displaced by drawing an elliptical arc centered on the midpoint of the driving roller 2 and the heating element 4. As the pressure is lowered downward, the pressing spring 8 is extended, so that the ring 6 and the endless film 1 are moved.
Contact pressure decreases.

That is, the endless film 1 moves in the direction B, the width W of engagement with the ring 6 decreases, and the rotational torque T
When the rotation torque T decreases, the contact pressure between the endless film 1 and the ring 6 is increased so as to increase the rotation torque T, and a rapid decrease in the rotation torque T can be avoided. Further, even when the endless film 1 moves in the direction A, the width W of engagement with the ring 6 increases, and the rotation torque T increases, the contact between the endless film 1 and the ring 6 decreases so that the rotation torque T decreases. The pressure can be reduced, and a sudden increase in the rotational torque T can be reduced.

In the first embodiment, the contact pressure between the ring 6 and the endless film 1 is changed in accordance with the displacement of the end portion of the driven roller 3 so that even if the surface roughness of the ring 6 is increased, By setting the cam surface shape 30a of the cam 30, the spring constant of the pressing spring 8, and the spring constant of the extension spring 10 so as to offset the rapid displacement of the rotation torque T of FIG. It is possible to realize a stable and endless film shift control device.

Embodiment 2 FIG. 2 is a schematic longitudinal sectional view showing an image forming apparatus in which a film type heating device to which the endless film shift control device of the present invention is applied is a heat fixing device. In FIG. 2, reference numeral 51 denotes an image forming apparatus main body;
Is a paper cassette, 53 is a paper feed roller for feeding the recording material P from the paper cassette 52, and 54 is a paper feed roller 53
A transport roller 55 for transporting the recording material P fed in the above-described manner onto a transport path is an exposure optical system, and forms an electrostatic latent image while scanning a document image on a photosensitive drum 56. The electrostatic latent image on the photosensitive drum 56 is developed with toner by a developing device 57,
The image is transferred to the recording material P by the transfer unit 58. The toner image on the recording material P is fixed on the recording material P by applying heat and pressure in the heat fixing device 59 as the film type heating device of the first embodiment. The recording material P that has passed through the heating device 59 is discharged to a discharge tray 61.

[0060]

As described above, according to the present invention,
Since the structure is provided with the tension varying means for displacing the film tension in accordance with the positional displacement of the end of the film support member by the film support member end displacement means, the shift detection member has a high coefficient of friction with the endless film. Even by changing the contact pressure between the endless film and the shift detecting member in accordance with the displacement of the end portion of the film spindle member, the sudden displacement of the end portion of the film spindle member is suppressed, and the frictional force changes. And a deviation detection member having a coarser surface roughness can be used, and a more stable endless film deviation control device can be realized.

According to the present invention, a spring is used as a tension generating means for the endless film by the film supporting member, and the cam is provided to the tension changing means for displacing the film tension in accordance with the displacement of the end of the film supporting member. , A stable endless film shift control device with a simple configuration can be realized without providing any electrical control mechanism.

Further, according to the present invention, bearings are provided at both ends of the driven roller, and the bearing at one end thereof is movable to a rotatable arm on a line connecting the arm rotation center and the driven roller axis. And a spring member having a cam surface sliding member with respect to the cam surface, and a spring member for urging the bearing between the one end bearing and the spring receiving portion to stretch and hang the endless film. Since the cam surface sliding member of the spring receiving portion is provided at a position closer to the arm rotation center than the driven roller axis, the cam surface sliding member slides on the cam surface with a simple structure. It is possible to reduce the moving distance, amplify the small displacement force of the driven roller end, and convert it to the operating force of the cam surface sliding member with respect to the cam surface, thereby reliably realizing a stable endless film control device. Further, according to the present invention, a fixed heating element,
A heat-resistant endless film that is hung and rotated between the heating element and at least one film support member, and a pressure member that sandwiches and conveys the recording material in close contact with the heating element via the endless film. Since the heat of the heating element is applied to the recording material via the endless film to heat and fix the image on the recording material, the running of the endless film is stabilized, and the fixing position in the width direction of the recording material is adjusted. It is possible to realize a film-type heating device that becomes constant and allows the recording material to pass while maintaining a constant position in the width direction during the fixing operation, and enables the endless film to run stably with time and thermal influence.

According to the invention, there is provided an image forming apparatus comprising: an image forming means for forming and supporting an unfixed image on a recording material; and a fixing means for heating and fixing the unfixed image formed and supported on the recording material. Since the fixing means is constituted by the film-type heating device of the present invention, there is an effect that an image forming apparatus capable of performing high-quality image formation without image distortion can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a main part of a film-type heating device to which an endless film shift prevention device according to a first embodiment of the present invention is applied.

FIG. 2 is a schematic vertical sectional view showing an image forming apparatus to which the film type heating device shown in FIG. 1 is applied.

FIG. 3 is a schematic configuration diagram of a film-type heating device to which a conventional endless film shift prevention device is applied.

FIG. 4 is a perspective view of a device for preventing the endless film from shifting in FIG. 3;

FIG. 5 is an explanatory view of the operation of the endless film shift prevention device of FIG. 4;

6 is an operation explanatory view of the endless film shift prevention device of FIG. 4;

[Explanation of symbols]

REFERENCE SIGNS LIST 1 endless film, 2 drive roller, 3 driven roller, 4 heating element, 5 pressure roller, 6 ring (film shift detecting member), 7 swing bearing, 8 spring (tension generating means), 9 control belt, 10 spring, 30 cams,
31 Spring support, 31a Projection shaft, 32 Arm 32
a axis.

Claims (5)

[Claims] 1. An endless film which is stretched across at least two or more film support members and which is rotatably supported at one end of at least one film support member. The end of the film shift detecting member is connected to the film shift detecting member, and the rotational movement of the film shift detecting member is changed to a linear motion when a rotational torque acts on the film shift detecting member by a frictional force with the endless film. A film spindle member end displacement means for converting the end of the film spindle member in a predetermined direction and changing the tension of the endless film in accordance with the displacement of the end of the film spindle member; An endless film shift prevention device comprising: 2. The endless film according to claim 1, wherein a spring is used as a tension generating means for the endless film, and a cam is used as a means for changing the film tension in accordance with the displacement of the end of the film support member. Film shift prevention device. 3. The bearing at one end of the film support member,
A spring receiving portion having a cam surface sliding member for a cam supported by the rotatable arm so as to be movable on a line connecting the arm rotation center and the film support shaft axis; A spring member for urging the bearing so that the endless film is stretched around the end bearing, and a cam surface sliding member of the spring receiving portion is provided at a position close to the arm rotation center. 3. The endless film shift prevention device according to claim 2, wherein: 4. A fixed heating element, a heat-resistant endless film that is hung and rotated between the heating element and at least one film support member, and a recording material that is interposed through the endless film through the endless film. 4. A pressure member that is held in close contact with a heating element to be conveyed, and the device for preventing endless film deviation according to claim 1, wherein the heat of the heating element is transferred by the endless film. 5. A film-type heating apparatus for applying an image on the recording material by heating and fixing the image on the recording material through the recording medium. 5. An image forming apparatus comprising: image forming means for forming and supporting an unfixed image on a recording material; and fixing means for heating and fixing the unfixed image formed and supported on the recording material.
6. The image forming apparatus according to claim 5, wherein the fixing unit is the film heating device according to claim 5.