JP2001175114A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device constituted so that jammed paper in a recording medium can be easily removed, a fixing belt can be prevented from being damaged at the time of releasing jamming and the recording medium can be prevented from being soiled at the time of restarting paper-passing after releasing the jamming. SOLUTION: A pressure roller 14 is directly and rotatably supported in a main frame 12, and a fixing roller 16 and a heating roller 18 stretching and supporting the fixing belt 34 are respectively rotatably supported in a 1st sub frame 20 held to freely slide on the main frame 12 by a 1st guide plate 36. When recording paper is jammed, the frame 20 is slid to separate the roller 16 from the roller 14 and widen a gap between the rollers 14 and 16, and then the jamming is released.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device for fixing unfixed toner on a recording medium.

[0002]

2. Description of the Related Art Recently, in a fixing device used in an electrophotographic image forming apparatus, a fixing belt is stretched between a fixing roller and a heating / tension roller (hereinafter simply referred to as a "heating roller"). A technique has been developed in which a belt fixing system provided with a pressure roller that presses from below through the fixing belt and preheating of a recording medium are combined.

[0003] In this way, the temperature of the nip can be set low by preheating, and by using a fixing belt having a small heat capacity, the temperature of the fixing belt is rapidly cooled when passing through the nip. And the cohesive force of the toner separated from the toner. Therefore, a clear fixed image with no offset can be obtained even when oil-less or only a small amount of oil is applied by improving the releasability between the fixing belt and the toner. Such a conventional fixing device is known as a fixing device that solves the problems of releasability and oil application that could not be solved by the heating roller method.

FIG. 6 is a schematic view showing the structure of a conventional belt-type fixing device as described above. The fixing device shown in FIG. 6 includes a fixing roller R1, a pressing roller R2 disposed immediately below the fixing roller R1, and a side (upstream side along the conveying direction of the recording medium D) of the fixing roller R1. The fixing belt B is stretched between the fixing roller R1 and the heating roller R3.

[0005] Above the fixing belt B, an oil application roller R4 is provided. A guide plate G as a recording medium support is provided below the fixing belt B with a gap therebetween, and a heating path for the recording medium D is formed between the lower portion of the fixing belt B and the guide plate G. . The fixing belt B obtains a desired tension when the heating roller R3 is pressed by the pressing lever U in a direction separating from the fixing roller R1, and is driven by the fixing roller R1 to be stable without slipping or loosening. Can rotate.

A heating heater H is provided as a heating source inside the heating roller R3, and a thermistor S is provided for measuring the surface temperature of the heating roller R3. The thermistor S is in contact with the non-sheet passing area of the fixing belt B instead of the sheet passing area of the fixing belt B in order to measure the temperature of the test portion in the contact state.

[0007]

In the above-described conventional belt-type fixing device, when the recording medium D moves in the direction of arrow P and the recording medium D becomes jammed between the fixing roller R1 and the pressure roller R2. In order to release the jam (paper jam) by rotating a knob (not shown) connected to the rotation shaft of the fixing roller R1 to forcibly rotate the fixing roller R1, and simultaneously pulling the recording medium D. I was

However, in this case, unfixed toner may adhere to the fixing belt B, and the fixing belt B may be stained with the toner. As described above, when the fixing belt B is stained by the toner, the toner that has stained the fixing belt B adheres to the recording medium D and becomes stained when the first printing operation after the jam is cleared. Also,
If the jam is released while pulling the recording medium D, the recording medium D may be broken in some cases, and a piece of paper remains inside the fixing device, and it is extremely difficult to remove the paper piece. Further, when the recording medium D is folded and a paper jam occurs, if the recording medium D with the paper jam is forcibly pulled out, the fixing belt B may be damaged.

SUMMARY OF THE INVENTION It is an object of the present invention to be able to easily remove a jammed recording medium and prevent the fixing belt from being damaged when the jam is cleared and the recording medium from being stained when the paper is restarted after the jam is cleared. An object of the present invention is to provide a fixing device.

[0010]

Means for Solving the Problems (First Invention) A fixing device according to a first invention is a fixing device for fixing unfixed toner on a recording medium, comprising a fixing roller and a fixing roller. A support roller disposed at a distance, a fixing belt endlessly stretched between the fixing roller and the support roller, a pressing roller that rolls on the fixing roller at a predetermined pressure via the fixing belt, a fixing roller, The heating device includes a heating device for heating the unfixed toner on the recording medium passing through the rolling contact portion of the pressure roller, and a release device for releasing the pressure contact state between the fixing roller and the pressure roller.

In the fixing device according to the present invention, the pressure contact state between the fixing roller and the pressure roller can be released by the release means, so that the fixing roller and the pressure roller can be easily separated. Therefore, there is no need to rotate the fixing roller or the like when removing the paper jammed recording medium, so there is no risk that the fixing belt will be stained with unfixed toner, and the recording medium will not be pinched. There is less possibility that the medium will be damaged and difficult to remove, or the fixing belt will be damaged. As described above, the jammed recording medium can be easily removed, and the fixing belt can be prevented from being damaged at the time of clearing the jam, and the recording medium can be prevented from being stained at the time of restarting the paper feeding after the clearing of the jam.

(Second Invention) In a fixing device according to a second invention, in the configuration of the fixing device according to the first invention, the releasing means includes a separating means for separating the fixing roller from the pressure roller. In this case, since the fixing roller can be separated from the pressure roller, the recording medium jammed with paper can be easily removed without rotating the fixing roller and the like, and the fixing belt is damaged when the jam is cleared and the jam is cleared. It is possible to prevent the recording medium from being stained when the paper passing is restarted later.

(Third Invention) In a fixing device according to a third invention, in the configuration of the fixing device according to the second invention, the separating means includes a movable frame for integrally holding the fixing roller and the support roller. The movable frame is supported so as to be displaceable in a direction for separating the fixing roller from the pressure roller. In this case, by displacing the movable frame that integrally holds the fixing roller and the support roller, the fixing roller can be easily displaced in a direction to separate the fixing roller from the pressure roller.

(Fourth invention) In a fixing device according to a fourth invention, in the configuration of the fixing device according to the third invention, the movable frame is supported movably in a direction to separate the fixing roller from the pressure roller. Is what is being done. In this case, by sliding the movable frame, the fixing roller can be easily displaced in a direction in which the fixing roller is separated from the pressure roller.

(Fifth invention) In a fixing device according to a fifth invention, in the configuration of the fixing device according to the third invention, the movable frame is rotatable in a direction in which the fixing roller is separated from the pressure roller. It is supported. In this case, by rotating the movable frame, the fixing roller can be displaced in a direction to separate the fixing roller from the pressure roller, so that the movable frame can be supported by a simpler support mechanism.

(Sixth invention) In a fixing device according to a sixth invention, in the configuration of the fixing device according to any one of the third to fifth inventions, the separating means further includes a displacement means for displacing the movable frame. Including. In this case, the movable frame can be displaced by the displacing means, and the fixing roller can be easily displaced in a direction for separating the fixing roller from the pressure roller.

(Seventh Invention) In a fixing device according to a seventh invention, in the configuration of the fixing device according to the sixth invention, the displacement means is a manual operation mechanism. In this case, even if the device does not operate due to a power failure or the like, the jam can be reliably released.

(Eighth Invention) In a fixing device according to an eighth invention, in the configuration of the fixing device according to the sixth invention, the displacement means is an electric drive mechanism. In this case, since the fixing roller can be automatically separated from the pressure roller, the jam can be easily released.

(Ninth Invention) In a fixing device according to a ninth invention, in the configuration of the fixing device according to any one of the sixth to eighth inventions, the displacement means is a link mechanism. in this case,
The link mechanism can constitute a displacement unit that effectively utilizes the space in the apparatus.

(Tenth Invention) In a fixing device according to a tenth invention, in the fixing device according to any one of the sixth to eighth inventions, the displacement means is a cam mechanism. In this case, the displacement mechanism can be downsized by the cam mechanism,
The degree of freedom of arrangement of the displacement means in the device can be improved, and the size of the device can be reduced.

(Eleventh invention) In a fixing device according to an eleventh invention, in the configuration of the fixing device according to any one of the third to tenth inventions, the movable frame is supported by the main frame so as to be displaceable. At the same time, it is detachably attached to the main frame.

In this case, since the fixing roller and the supporting roller are integrally held by the movable frame, the fixing roller and the like can be easily or individually replaced by removing the movable frame.

(Twelfth Invention) In a fixing device according to a twelfth invention, in the configuration of the fixing device according to any one of the first to eleventh inventions, the heating means is disposed in the support roller, And a heat source that heats a portion of the fixing belt on the support roller through the fixing roller. In this case, since the heat from the heat source can be transmitted to the fixing belt via the support roller, the unfixed toner on the recording medium can be satisfactorily heated.

(Thirteenth Invention) A fixing device according to a thirteenth invention is the fixing device according to the twelfth invention, wherein
The heat source is attached to the main frame. In this case, it becomes easy to supply power to the heat source.

(Fourteenth Invention) A fixing device according to a fourteenth invention is a fixing device according to any one of the first to thirteenth inventions, which applies a release agent to the outer peripheral surface of the fixing belt. Is further provided. In this case, since the releasing agent can be applied to the outer peripheral surface of the fixing belt by the applying unit, the releasing property between the fixing belt and the toner can be improved.

(Fifteenth Invention) A fixing device according to a fifteenth invention is the fixing device according to the fourteenth invention, wherein
The application means is attached to the main frame. In this case, the application means can be stably mounted in the apparatus with a minimum necessary space.

(Sixteenth Invention) A fixing device according to a sixteenth invention is the fixing device according to the fourteenth invention, wherein
Further provided is a coating means frame for holding the coating means,
The coating means frame is detachably attached to the main frame.

In this case, the coating means can be easily removed by removing the coating means frame from the main frame, and the maintenance work of the coating means can be made more efficient.

(Seventeenth Invention) In a fixing device according to a seventeenth invention, in the configuration of the fixing device according to any one of the first to sixteenth inventions, the pressure roller is a driving roller. In this case, the pressure contact state between the fixing roller and the pressure roller can be released by moving the fixing roller away from the pressure roller without moving the pressure roller. Can be easily transmitted to the pressure roller.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a fixing device according to the present invention will be described. The fixing device of the present invention can be suitably used for an electrophotographic image forming apparatus such as a copying machine, a printer, and a facsimile.

(First Embodiment) Hereinafter, a first embodiment of the present invention will be described.
The fixing device according to the embodiment will be described. FIG.
FIG. 1 is a schematic sectional view illustrating a configuration of a fixing device according to a first embodiment of the present invention.

The fixing device 10 shown in FIG. 1 includes a main frame 12 as a base, and a pressure roller 14 is supported on the main frame 12 so as to be rotatable around a fixed axis. The main frame 12 includes a first sub-frame 20 on which the fixing roller 16 and the heating roller 18 are rotatably supported, a donor roller 22 and an oil roller 24.
And a second sub-frame 28 on which the cleaning roller 26 is rotatably supported, each of which is movably mounted.

The fixing roller 16 has a cylindrical metal core made of aluminum, and the outer surface of the metal core is coated with silicone rubber to a predetermined thickness. Pressure roller 14
Has an iron cylindrical core, and the outer surface of the core is thinly coated with silicone rubber. The pressure roller 14 is rotationally driven by a drive motor (not shown), and functions as a drive roller. The heating roller 18 has a cylindrical cored bar made of aluminum, and the outer surface of the cored bar is coated with fluororubber. Two halogen heaters 30 and 32 are inserted inside the cored bar. I have. The halogen heaters 30 and 32 are fixed to the main frame 12 in consideration of convenience such as energization.

The first sub-frame 20 that rotatably supports the fixing roller 16 and the heating roller 18 is moved relative to the pressure roller 14 by a first guide plate 36 integrally attached to the main frame 12. It is slidably supported along the linear direction indicated by arrow C so as to advance and retreat. The first sub-frame 20 is urged by a spring 38 (see FIG. 2) in a direction in which the fixing roller 16 is separated from the pressure roller 14. The first sub-frame 20 is detachable from the main frame 12 with the spring 38 removed.

The fixing roller 16 and the heating roller 18 include
A fixing belt 34 in which silicone rubber is coated on an endless substrate made of a polyimide resin is stretched endlessly, and the fixing roller 16 and the pressure roller 14 are in pressure contact with each other via the fixing belt 34. Therefore, in a state where the fixing belt 34 is in frictional engagement with the pressure roller 14 or in a state where a recording paper serving as a recording medium is interposed therebetween, the fixing belt 34 is driven endlessly by being rotationally driven. Will be.

The main frame 12 has an introduction-side guide member 40 for guiding the recording paper to which the unfixed toner image has adhered toward a rolling contact portion (nip portion) between the fixing roller 16 and the pressure roller 14. A discharge side guide member 42 for discharging the recording paper after the fixing operation to the outside is attached.

Here, the heat generated by the halogen heaters 30 and 32 heats the heating roller 18 from the inside and is transferred to the fixing belt 34 which is wrapped around the heating roller 18 and adheres to the outer peripheral surface thereof. Become. The thus heated fixing belt 34 frictionally engages with the pressure roller 14 in response to the rotation of the pressure roller 14 and travels endlessly. Then, the fixing belt 34 is connected to the introduction-side guide member 4 at a nip portion defined between the fixing roller 16 and the pressure roller 14.
The unfixed toner image that has been sandwiched at a predetermined pressure together with the recording paper (not shown) guided through the recording paper 0 and is already adhered to the recording paper is heated and pressed and fixed on the recording paper. The recording paper on which the fixing operation has been completed in this way is discharged out of the main frame 12 via the discharge side guide member 42.

On the other hand, on the second sub-frame 28 described above, the donor roller 22 which is in contact with the surface of the fixing belt 34 is provided.
Are rotatably supported. The donor roller 22 has a function of applying a release oil to the fixing belt 34 and a function of releasing toner adhered to the fixing belt 34 without being fixed on the recording paper and attaching the toner to its own outer peripheral surface. A cleaning roller 26 made of felt for removing the toner adhered thereto is in rolling contact with the outer peripheral surface of the donor roller 22.

The cleaning roller 26 is rotatably supported by the second sub-frame 28. Further, an oil roller 24 formed by winding a nonwoven fabric and impregnated with a release oil is in rolling contact with the outer peripheral surface of the donor roller 22 in a state of being located downstream of the cleaning roller 26 in the rotation direction of the donor roller 22. The oil roller 24 is also a second
Is rotatably supported by the sub-frame 28.

Here, the second sub-frame 28 that rotatably supports the donor roller 22, the oil roller 24, and the cleaning roller 26 needs to be replaced every time these rollers form a specific number of images. For this reason,
The second sub-frame 28 is formed by a second guide plate 44 integrally attached to the main frame 12.
It is configured to be slidable along a linear direction indicated by an arrow D so as to advance and retreat with respect to the fixing belt 34, that is, to be removable.

Next, a jam release mechanism (a mechanism for separating the pressure roller 14 from the fixing roller 16) will be described. FIG.
FIG. 2 is a schematic diagram mainly showing a configuration of a jam release mechanism of the fixing device shown in FIG. 1. FIG. 2 illustrates a non-operation state of the jam release of the fixing device illustrated in FIG. 1.

As shown in FIG. 2, the first subframe 2
At 0, a cylindrical bearing 46 is fixed in an upright state, and the above-mentioned fixing roller 16 is rotatably supported on the bearing 46. On the other hand, a pin 48 is attached to the main frame 12 in an upright state while being positioned below the fixing roller 16 in the drawing and adjacent to the first sub-frame 20.

The lower end of the first lever 50 in the figure is rotatably supported by the pin 48, and extends upward in the figure. In the middle of the first lever 50, an arc-shaped pressing portion 50a for pressing the bearing 46 described above is formed. Further, an elongated hole 50b extending along the longitudinal direction of the first lever 50 is formed at the upper end in the drawing.

Further, the fixing roller 16 and the pressure roller 1
Above each end of No. 4, a second lever 52 having a substantially L-shape inverted right and left is provided so as to extend over both sides, with its bottom side extending left and right in the figure. ing. The second lever 52 is rotatably supported by a pin 54 fixed with its right end in the figure upright on the main frame 12, and engages with the above-described elongated hole 50 b at the upper end in the figure. The pin 56 is fixed. Thus, the first
The second lever 52 rotates in conjunction with the movement of the lever 50 of FIG.

At the left end of the second lever 52 in the figure,
The pin 58 is fixed in an upright state. This pin 5
8, an upper end of a third lever 60, which is located to the left of the pressure roller 14 in the drawing and extends substantially in the vertical direction, is rotatably supported. On the other hand, the third lever 6
The pin 62 is attached to the lower end of the “0” in an upright state.

A fourth lever 66 extending substantially vertically is provided in a state where the pressing roller 14 is located on the left side in the drawing. The upper end of the fourth lever 66 in the figure is rotatably supported by a pin 64 fixed in a state of standing on the main frame 12. On the other hand, a long hole 66a extending in the longitudinal direction is provided at the lower end of the fourth lever 66 in the drawing, and the pin 62 described above is engaged with the long hole 66a.

A compression spring 68 is stretched between the pin 62 and the pin 64 for elastically holding the third and fourth levers 60 and 66 at the positions shown in FIG.
That is, the compression spring 68 urges the pin 62 downward in the figure as indicated by the arrow G. This allows the third and fourth
Of the levers 60 and 66 extend downward on the same axis in the drawing. As a result, the first and second
The positions of the levers 50 and 52 of the fixing roller 16 are fixed.
The state in which the pressure roller 14 and the pressure roller 14 are pressed against each other with a predetermined pressure is maintained by the first lever 50.

In the present embodiment, the first sub-frame 20 and the first to fourth levers 50, 52, 6
Reference numerals 0 and 66 correspond to a releasing unit and a separating unit, the halogen heaters 30 and 32 correspond to a heating unit and a heat source, and the heating roller 18 corresponds to a support roller. The second sub-frame 20 corresponds to a movable frame, the first to fourth levers 50, 52, 60, and 66 correspond to displacement means, a manual operation mechanism, and a link mechanism. Corresponds to the application unit, and the second sub-frame 28 corresponds to the application unit frame.

Next, the operation of the fixing device of the present embodiment configured as described above will be described. First, the fixing operation will be described with reference to FIG.

The recording paper on which the toner image has been adhered is transported into the main frame 12 through a path defined by the introduction-side guide member 40 by an electrophotographic process (not shown). Then, the sheet is nipped between the fixing roller 16 and the pressure roller 14 via the fixing belt 34. The temperature of the halogen heaters 30 and 32 is controlled in advance by a thermistor (not shown), and the fixing belt 34 is heated so that the nip between the fixing roller 16 and the pressure roller 14 has a temperature suitable for fixing. ing.

Here, the pressing roller 14 serving as a driving roller
The rotation of the fixing belt 3 in the direction indicated by arrow E
The fixing roller 16 frictionally engaged with the fixing roller 4 through the
Will rotate in the direction indicated by. As a result, the unfixed toner image carried on the recording paper is heat-fixed to the recording paper by the heat of the fixing belt 34 when passing through the nip portion, and at the same time, is applied between the fixing roller 16 and the pressure roller 14. Pressed. Thus, the unfixed toner image is fixed on the recording paper under pressure and heat. Thereafter, the recording paper on which the fixing operation has been completed is discharged out of the main frame 12 through a path defined by the discharge side guide member 42. Thus, a series of fixing operations is completed.

Next, the jam clearing operation will be described.
FIG. 3 is a schematic diagram showing an operation state of the jam release mechanism of the fixing device shown in FIG.

When it is determined that the recording paper is jammed in the nip, the operator opens a work door (not shown),
In the non-operation state of the jam release shown in FIG. 2, the fourth lever 66 is manually operated by the operator's finger in the left direction in the drawing, that is, in the direction shown by the arrow H, against the urging force of the compression spring 68. Move to pull.

As a result of this movement, the fourth lever 66 rotates clockwise about the pin 64 as shown in FIG. 3 as the jam release operation state, and the third lever 60 similarly releases the pin 58. It will be lifted upward while rotating clockwise in the figure to the center.

At the same time, the second lever 52 is
4 is rotated clockwise in the figure as shown by arrow I,
In conjunction with this, the first lever 50 rotates clockwise in the figure as indicated by the arrow K about the pin 48. Accordingly, the first sub-frame 20 includes a spring 38
Urged in the direction away from the pressure roller 14, and moves rightward in the figure as shown by the arrow L.

Here, since the fixing roller 16 is attached to the first sub-frame 20, the fixing roller 16 and the pressure roller 14 are moved with the movement of the first sub-frame 20.
And the pressure contact state is released. As a result,
The recording paper can be pulled out from the jam release operation state shown in FIG. 3, and a paper jam of the recording paper can be released.

According to the present embodiment, in addition to the above-described effects, the fixing roller 16, the heating roller 18, and the fixing belt 34 are integrally held by the first sub-frame 20, so that the first By removing the sub-frame 20 from the main frame 12, the sub-frame 20 can be easily or individually replaced. Note that the first subframe 2
0 is removed because the halogen heaters 30 and 32 are fixed to the main frame 12.
This is carried out after removing 0, 32 from the heating roller 18.

Further, according to the present embodiment, by removing the second sub-frame 28 from the main frame 12, the donor roller 22, the oil roller 24 and the cleaning roller 26 can be removed at a time. This means that considering that the rollers 24 and 26 are consumables, the replacement work can be easily performed and the maintenance work can be made more efficient.

(Second Embodiment) Next, a second embodiment of the present invention will be described.
The fixing device according to the embodiment will be described. FIG.
FIG. 5 is a schematic diagram showing a non-operation state of a jam release mechanism of the fixing device according to the second embodiment of the present invention, and FIG. 5 is a schematic diagram showing an operation state of the jam release mechanism of the fixing device shown in FIG. It is. In the present embodiment, the jam release mechanism is provided by the first to fourth levers 5 shown in FIGS.
The link mechanism constituted by 0, 52, 60, 66 and the like is changed to a cam mechanism constituted by the first lever 50 and the disc cam member 72 shown in FIGS. The second embodiment is the same as the first embodiment except that the cleaning roller 26 is fixed to the main frame 12.

As shown in FIGS. 4 and 5, the donor roller 22, the oil roller 24 and the cleaning roller 2
Reference numeral 6 is attached to the main frame 12 so as to be rotatably supported. In this case, the donor roller 2 can be used without using the second sub-frame 28 shown in FIG.
2. Since the oil roller 24 and the cleaning roller 26 can be attached, the configuration is simplified, and the cost and size can be reduced. In this embodiment, it is also possible to attach the main frame 12 via the second sub-frame 28 as in the first embodiment.

Next, as shown in FIG.
The fixing roller 16 and the fixing roller 16 are urged by a spring 70 in a direction in which they are pressed against each other. The spring 70 has one end locked to the upper end of the first lever 50 and the other end connected to the main frame 12.
, And urges the first lever 50 in the direction indicated by the arrow M so as to rotate around the pin 48 in the counterclockwise direction in the figure. On the left side of the first lever 50 in the drawing, a disk cam member 72 is fixed in an eccentric manner to a drive pin 74 rotatably supported by the main frame 12. The drive pin 74 is connected to a rotary solenoid (not shown) as an electric drive mechanism.

The disk cam member 72 has a circumferential cam surface on the outer peripheral surface. The cam surface has a minimum eccentric portion 72a having the minimum eccentric amount from the drive pin 74 and a maximum eccentric portion having the maximum eccentric amount. The eccentric portion 72b is provided 180 degrees apart from the eccentric portion 72b. Here, during the fixing operation, a control device (not shown) drives and controls the rotary solenoid, and its rotational position is defined so that the minimum eccentric portion 72 a faces the first lever 50. As described above, the first lever 50 is attached to the minimum eccentric portion 72 a of the disc cam member 72 by the spring 7.
In a state where the fixing roller 16 and the pressing roller 14 are pressed by the pressing portion 50a of the first lever 50 in a state where the fixing roller 16 and the pressing roller 14 are in contact with each other by the urging force of 0, the fixing roller 16 and the pressing roller 14 are pressed with a predetermined pressing force required for the fixing operation. .

On the other hand, in the fixing operation state shown in FIG. 4 (that is, the state in which the jam release mechanism is not operated), if the recording paper is jammed in the nip portion between the fixing roller 16 and the pressure roller 14, the operator Turns on a pressure release switch on an operation panel (not shown), and a rotary solenoid is driven by a control device (not shown). As a result, the disk cam member 72 rotates and the maximum eccentric portion 7 of the disk cam member 72
2b is opposed to the first lever 50, and the first lever 50 is turned around the pin 48 in the clockwise direction in the figure against the urging force of the spring 70. As a result, the jam release operation state shown in FIG. 5 is established, the pressure contact state between the fixing roller 16 and the pressure roller 14 is released, and the jammed recording paper can be easily taken out.

Here, by providing an auxiliary spring for urging the first sub-frame 20 in a direction in which the fixing roller 16 supported by the first sub-frame 20 is separated from the pressure roller 14, the first lever 50 is moved from FIG. As shown in FIG. 5, it may be ensured that the rollers 14 and 16 are separated from each other when they are turned clockwise in the drawing. In this case,
Needless to say, the urging force of this auxiliary spring is set smaller than the urging force of the spring 70.

As described above, according to the present embodiment, when a paper jam occurs in the recording paper, the pressure release switch or the like is turned on to automatically switch between the fixing roller 16 and the pressure roller 14. The pressure can be released, and the jam releasing operation can be easily performed.

In the present embodiment, subframe 2
0, the first lever 50 and the disk cam member 72 correspond to the releasing means and the separating means, and the halogen heaters 30 and 32
Corresponds to a heating means and a heat source, and the heating roller 18 corresponds to a support roller. Further, the second sub-frame 20 corresponds to a movable frame, the first lever 50 and the disc cam member 72 correspond to a displacement unit, an electric operation mechanism and a cam mechanism, and the donor roller 22 and the oil roller 24 correspond to an application unit. Equivalent to.

It is needless to say that the present invention is not limited to the configuration of each of the above-described embodiments, but can be variously modified without departing from the gist of the present invention.

For example, in each of the above-described embodiments, the first sub-frame 20 is slid in the horizontal direction to separate the fixing roller 16 and the pressure roller 14 from each other. The frame 20 can be rotatably supported, and the first sub-frame 20 itself can be rotated to separate the fixing roller 16 and the pressure roller 14 from each other.

In each of the above embodiments, the fixing roller 16, the heating roller 18, and the fixing belt 34 are integrally held by the first sub-frame 20, but only the fixing roller 16 is a pressure roller. It is also possible to adopt a configuration in which the distance is larger than 14.

In the first embodiment, the fourth lever 66 has been described to be manually moved by the operator's finger. However, the present invention is not limited to such a configuration. As an electric drive mechanism, for example, a rotary solenoid is connected to the upper end of the fourth lever 66 in the figure, and by energizing the rotary solenoid, the fourth lever 66 is automatically rotated around the pin 64 as a rotation center. It is also possible. Conversely, in the second embodiment, the disc cam member 72 has been described to be rotationally driven by an electric drive mechanism such as a rotary solenoid, but it is needless to say that the disc cam member 72 may be manually rotated. No.

When an electric drive mechanism is used, the rotary solenoid may be automatically activated in response to the power-off operation to bring the rotary solenoid to the state shown in FIG. 3 or FIG. In this state, the pressure contact state between the fixing roller 16 and the pressure roller 14 is automatically released. As a result, the deformation of the fixing belt 34 in the nip portion in the direction opposite to the endless running state is eliminated, the excessive load on the fixing belt 34 is reduced, and the life of the fixing belt 34 can be extended.

Further, the first sub-frame 20 is moved forward and backward by the first to fourth levers 50 and 50 in the first embodiment.
The link mechanism constituted by 52, 60, 66
In the above-described embodiment, the operation is performed via the cam mechanism constituted by the first lever 50 and the disc cam member 72. However, the present invention is not limited to such a configuration, and the first embodiment is not limited thereto. Another mechanism may be used as long as it can drive the sub-frame 20 forward and backward with respect to the pressure roller 14.

[0073]

As described above, according to the present invention, the pressure-contact state between the fixing roller and the pressure roller can be released by the release means, so that the paper jammed recording medium can be easily removed. It is possible to prevent the fixing belt from being damaged when the jam is cleared, and to prevent the recording medium from being stained when the paper is restarted after the jam is cleared.

[Brief description of the drawings]

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

FIG. 2 is a schematic diagram mainly showing a configuration of a jam release mechanism of the fixing device shown in FIG. 1;

FIG. 3 is a schematic diagram showing an operation state of a jam clearing mechanism of the fixing device shown in FIG. 1;

FIG. 4 is a schematic diagram illustrating a non-operating state of a jam clearing mechanism of a fixing device according to a second embodiment of the present invention.

FIG. 5 is a schematic diagram showing an operation state of a jam release mechanism of the fixing device shown in FIG. 4;

FIG. 6 is a schematic diagram showing a configuration of a conventional belt-type fixing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Fixing apparatus 12 Main frame 14 Pressure roller 16 Fixing roller 18 Heating roller 20 First sub-frame 22 Donor roller 24 Oil roller 26 Cleaning roller 28 Second sub-frame 30, 32 Halogen heater 34 Fixing belt 36 First guide Plate 38, 70 Spring 40 Inlet-side guide member 42 Discharge-side guide member 44 Second guide plate 46 Bearing 48, 54, 56, 58, 62, 64 Pin 50 First lever 50a Pressing portion 50b, 66a Slot 52 Second lever 60 Third lever 66 Fourth lever 68 Compression spring 72 Disk cam member 72a Minimum eccentric portion 72b Maximum eccentric portion 74 Drive pin

Continuing on the front page (72) Inventor: Kino Tanaka, 1006, Kazuma, Kazuma, Osaka Prefecture, Matsushita Electric Industrial Co., Ltd. (72) Inventor: Daimitsu Shimazaki, 1006, Kazuma, Kazuma, Kadoma, Osaka Pref. Inventor Keiichi Matsuzaki 1006 Kazuma Kadoma, Kazuma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Inventor Yasuhisa Yoshimoto 1006 Kadoma Kazuma, Kadoma City, Osaka Pref. Matsushita Electric Industrial Co., Ltd. 1-5-12 Shiba, Nitto Kogyo Co., Ltd. (72) Inventor Takeshi Kato 1-5-12 Shiba, Minato-ku, Tokyo Nitto Kogyo Co., Ltd. F-term (reference) 2H033 BA02 BA06 BA11 BB01 BB35

Claims (17)

[Claims] 1. A fixing device for fixing unfixed toner on a recording medium, comprising: a fixing roller; a support roller disposed apart from the fixing roller; and a fixing roller and the support roller. A fixing belt that is endlessly wound around the fixing belt, a pressure roller that rolls in contact with the fixing roller at a predetermined pressure via the fixing belt, and a recording medium that passes through a rolling contact portion of the fixing roller and the pressure roller. A heating unit for heating the unfixed toner, and a release unit for releasing a pressure-contact state between the fixing roller and the pressure roller. 2. The fixing device according to claim 1, wherein the release unit includes a separation unit that separates the fixing roller from the pressure roller. 3. The separation unit includes a movable frame that integrally holds the fixing roller and the support roller, and the movable frame is supported so as to be displaceable in a direction that separates the fixing roller from the pressure roller. 3. The fixing device according to claim 2, wherein the fixing device is used. 4. The fixing device according to claim 3, wherein the movable frame is movably supported in a direction in which the fixing roller is separated from the pressure roller. 5. The fixing device according to claim 3, wherein the movable frame is rotatably supported in a direction to separate the fixing roller from the pressure roller. 6. The fixing device according to claim 3, wherein the separation unit further includes a displacement unit that displaces the movable frame. 7. The fixing device according to claim 6, wherein the displacement unit is a manual operation mechanism. 8. The fixing device according to claim 6, wherein the displacement unit is an electric drive mechanism. 9. The fixing device according to claim 6, wherein the displacement unit is a link mechanism. 10. The fixing device according to claim 6, wherein the displacement unit is a cam mechanism. 11. The movable frame according to claim 3, wherein the movable frame is supported by the main frame so as to be freely displaceable, and is detachably attached to the main frame. Fixing device. 12. The heating device according to claim 1, wherein the heating unit includes a heat source disposed in the support roller and configured to heat a portion of the fixing belt on the support roller via the support roller. 12. The fixing device according to any one of 11. 13. The fixing device according to claim 12, wherein the heat source is mounted on a main frame. 14. The fixing device according to claim 1, further comprising an application unit for applying a release agent to an outer peripheral surface of the fixing belt. 15. The fixing device according to claim 14, wherein the application unit is attached to a main frame. 16. The fixing device according to claim 14, further comprising an application unit frame for holding the application unit, wherein the application unit frame is detachably attached to a main frame. 17. The fixing device according to claim 1, wherein the pressure roller is a driving roller.