JP2000338808A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a fixing device which causes no size increase and no malfunction and is safe. SOLUTION: The fixing device has a heating roller 7 which forms a nip section together with a pressure roller and incorporates a halogen heater 6 in a heating roller main body for melting unfixed toner image on a recording material passing the nip section and fixing the image on the recording material by heating and pressurizing. Further, electric power is supplied via electrodes at both ends of the halogen heater 6. In this fixing device, caps 17a, 17b made of heat-resistant electrical insulating material are provided at least one end part of the heating roller main body.

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 an unfixed toner image, which is provided in an image forming apparatus such as an electrophotographic apparatus, an electrostatic recording apparatus, and a laser beam printer, to a recording material by heating and melting the image. is there.

[0002]

2. Description of the Related Art In a fixing device provided in an image forming apparatus such as an electrophotographic apparatus, an electrostatic recording apparatus, and a laser beam printer, means for fixing a toner image transferred onto a recording material include heat fixing and pressure fixing. There is a method of fixing under heat and pressure through a heat-resistant sheet, and a fixing method utilizing heat is generally used in many cases.

FIGS. 8, 9 and 10 show an example of a conventional fixing device for performing heat fixing. FIG. 8 is a front view of a fixing device including a heating roller including a heating element (halogen heater) and a pressing roller pressed against the heating roller. Figure 9 is the cross sectional view, FIG. 10 is the arrow X ₁ view of the heating element.

The housing of the fixing device 1 includes a frame 2, a stay 3, and left and right covers 4 and 5. In the fixing device 1, a hollow heating roller 7 in which a halogen heater 6 is disposed and a pressure roller 8 in which an outer periphery of a core bar 8a is covered with an elastic member are disposed.

The halogen heater 6 includes a jacket tube (quartz tube) 6
c, a filament 6d is housed inside, and both ends are provided with electrodes 6a, 6b for supplying power to the filament 6d.
A configuration in which adhesive sealing is performed with e and 6f is generally known.

[0006] One base 6e of the halogen heater 6 is
The other base 6f is supported by a support portion 4a provided on the left cover 4, and the other base 6f is elastically supported by the right cover 5 by a spring 14 in consideration of the thermal expansion of the halogen heater 6. The electrodes 6a and 6b at both ends are connected to a core wire 16a (16
b), connected to the power drive source 15 via the crimping member 6g (6h) and the conductive wire 6i (6j).

[0007] Side portions 2 formed on both sides of the frame 2
Bearings 9a and 9b are attached to a and 2b, and the heating roller 7 is rotatably supported by these bearings 9a and 9b.

Reference numerals 18a and 18b denote locking rings which lock the heating roller 7 so as not to move in the axial direction.

The protruding portions 8b, 8c of the core 8a of the pressure roller 8 are rotatably supported by bearings 10a, 10b provided on both side surfaces 2a, 2b of the frame 2.

A driving gear 11 is connected to (engages with) an output gear of a driving source (not shown) at one end of the heating roller 7.
The bearings 10a and 10b that support the projecting portions 8b and 8c at both ends of the metal core 8a of the pressure roller 8 are provided with cut-and-raised portions 2 provided on both side surfaces 2a and 2b of the frame 2.
The pressure roller 8 is biased in the direction of the heating roller 7 by being supported by the ends of springs 12a and 12b disposed at c and 2d. Accordingly, the pressure roller 8 is driven by the drive gear 11 to rotate in a state in which the pressure roller 8 comes into contact with the heating roller 7 to form a pressure contact nip portion as a fixing portion.

The heating roller 7 is maintained so that the surface temperature of the heating roller 7 becomes constant by turning on and off the halogen heater 6 by a temperature control means (not shown).

After the completion of the transfer, a transfer material (not shown) carrying the unfixed toner image advances in the direction perpendicular to the plane of the drawing and is supplied to a contact portion (nip portion) of the rollers 7 and 8.
Upon receiving pressure and heat at the nip portion, the fused toner image is fixed on the transfer material and discharged outside the machine, or fed again for image formation on the back surface.

[0013]

However, usually,
In order to prevent electric shock, a minimum space distance for insulation between the live part and a metal member adjacent thereto is defined. That is, in FIGS. 9 and 10, the minimum spatial distance is defined as a distance between the sealing joint (active portion) of the conductive tube 6 i and the base 6 f between the sheath tube 6 c and the base 6 f as indicated by the symbol A in the drawing. This is the distance to the metal part (C in the figure, in this case, the end of the roller body), and it was necessary to secure a certain amount of this minimum spatial distance.

The minimum spatial distance I ₁ on the right shown in FIG. 9 is the distance between points AB + the distance between points BC, and the minimum spatial distance I ₂ on the left shown in FIG. 10 is the distance between the points AD + point the distance between the distance + points EC between DE, if the heater shape of Figure 10 showing the left portion of FIG. 9 and the heater showing the right side of the heater shown in FIG. 8, the minimum space distance I ₁ Since I ₂ satisfies I ₁ <I ₂ , the actual minimum spatial distance in the fixing device is I ₁ . In particular, when a high voltage is applied to the heating roller 7, a longer distance is required for safety. Due to these circumstances, the length (L1 in FIG. 8) of the halogen heater 6 was naturally determined.

An object of the invention according to the present application is to solve these technical problems, and an object of the invention is to provide a fixing device that is safe without causing a malfunction without enlarging the device. It is assumed that.

[0016]

A first configuration of a fixing device for realizing the object of the invention according to the present application includes a power supply unit,
A cylindrical heating roller rotatably supported by enclosing a heating element connected to the power supply means via electrodes provided at both ends, and at least one end of the heating roller. Provided with a cap made of a heat-resistant electric insulating material.

A second configuration of the fixing device for realizing the object of the invention according to the present application is the same as the first configuration, except that a gear for transmitting a driving force to the heating roller is formed in a part of the cap. is there.

A third configuration of the fixing device for realizing the object of the invention according to the present application is the fixing device according to any one of the above configurations, wherein the fixing device is provided between the heating roller and a supporting member that rotatably supports the heating roller. The cap is provided.

According to a fourth aspect of the present invention, there is provided a fixing device according to any one of the above aspects, wherein the outer end of the cap has a wall extending toward a radial center. It is.

According to the above configuration, since the metal portion of the heating roller is covered with the heat-resistant electrical insulating member, it is possible to provide a fixing device which is free from malfunction and malfunction by preventing noise and leakage and has high safety. Further, since the distance between the electrode portion of the heating element and the metal portion of the heating roller can be reduced, the size of the apparatus can be reduced.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) The present invention will be described below with reference to an embodiment shown in the drawings.

FIG. 1 is a front view of a fixing device according to the present embodiment, and its basic structure is shown in FIGS.
Is the same as that of the conventional fixing device shown in FIG. 1, and corresponding portions are denoted by the same reference numerals and description thereof will be omitted unless necessary.

As shown in FIGS. 1, 2, 3 and 4,
In this embodiment, caps 17a, 17 made of a heat-resistant electric insulating material are provided at both ends of the roller body of the heating roller 7.
b is attached.

Each of the caps 17a and 17b has a protruding claw 17c formed symmetrically about the axis on the outer peripheral surface of the cylindrical portion on the inner surface side of the flange portion, and is provided near both ends of the roller body of the heating roller 7. Holes 7a and 7b and caps 7c and 7d
By inserting the pair of claws 17c of 7a and 17b, the caps 17a and 17b are locked to both ends of the roller body made of metal of the heating roller 7.

In the present embodiment, the caps 17a, 1
7b is formed of a heat-resistant electric insulating material as described above. As the heat-resistant electric insulating material in the present embodiment, an electric insulating resin material that can withstand a high temperature of 200 ° C. or more is used. PET, PPS, PBT,
An LCP or the like is used.

As described above, in this embodiment, the caps 17a and 17b are attached to both ends of the metallic roller body of the heating roller 7, respectively, and the end faces of the roller body are covered with the caps. In this case, the end face of the roller body is covered by the axial length of the cylindrical portion of the cap 17a (17b).

Therefore, the metal surface of the inner surface of the roller body of the heating roller 7 in which the halogen heater 6 is provided is not exposed from the end surface only in the portion covered with the caps 17a and 17b.

For this reason, the electrodes 6a,
6b and the minimum space for insulation between the metal part of the heating roller 7
Distance I_Three In FIGS. 2 and 4, I_Three = Point AB + Point BF +
The point FG is obtained. When there are no caps 17a and 17b
Minimum spatial distance I of_Four In FIGS. 2 and 4, I_Four = Point AB
+ Point BC = I₁ (Same as the conventional embodiment), and I _Three 
> I_Four (= I₁ ).

Therefore, the caps 17a and 17b are set so that the minimum spatial distance I ₄ (= I ₁ ) with respect to the insulation shown in the conventional example is equal to the spatial distance I ₃ shown in the present embodiment.
Is determined, the halogen heater 6 and the base and 6e,
The distance between the sealing joints 6k and 6l of 6f and the heating roller 7 can be reduced. That is, the halogen heater 6
Can be made shorter than before (L ₁ > L ₂ ).

(Second Embodiment) FIG. 5 shows a second embodiment of the present invention.
An embodiment will be described.

In FIG. 5, the same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 5, reference numeral 19 denotes a cap which is attached to one end of the roller body of the heating roller 7 and also serves as a driving gear made of a heat-resistant electrically insulating member.

In this embodiment, the cap 19, which also serves as a driving gear, comprises a cap body 19a having a groove inserted into the end of the roller body, and a gear 19b.
The cap body 19a is formed with an engaging claw 19a that engages with a locking hole of the roller body on an inner peripheral surface of the cap body 19a with the groove interposed therebetween, and an outer peripheral cylinder that sandwiches the groove of the cap body 19a. The part is in contact with the bearing 9b.

According to the present embodiment, the cap body 1
9a has the function of the gear locking ring 18a used in the related art and the first embodiment.
Becomes unnecessary, and the cost can be reduced.

(Third Embodiment) FIG. 6 illustrates a third embodiment of the present invention. Here, portions similar to those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

In FIG. 6, reference numeral 20 denotes a cap made of a heat-resistant electrically insulating member attached to one end of the roller body of the heating roller 7. The cap 20 has a locking claw 2 on the inner peripheral side with a groove inserted into the end of the roller body interposed therebetween.
0a, and a cylindrical tubular portion 20b on the outer peripheral side is formed,
A stepped portion 2 into which the bearing 9a is fitted is formed on the outer peripheral portion of the cylindrical portion 20b.
0c is formed.

According to the present embodiment, since the cylindrical portion 20b of the cap 20 is sandwiched between the roller body of the heating roller 7 and the bearing 9a, the cylindrical portion 20b transfers the heat generated by the heating roller to the bearing. 9a can be prevented to some extent, and deterioration of the bearing can be prevented. The roller 7 also serves as an insulator.

(Fourth Embodiment) FIG. 7 shows a fourth embodiment. Here, portions similar to those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

The cap 21 according to the present embodiment has the locking claws 21a, 21b provided in the holes 7c,
It is locked by entering 7d. Cap 2
A wall surface 21c extending to the center in the radial direction is formed at the outer end of 1. Since the wall surface 21c is close to the vicinity of the halogen heater 6, it is possible to prevent the radiation heat of the halogen heater 6 from leaking to the outside of the heating roller 7, so that power consumption can be suppressed. Further, since the light from the halogen heater 7 is hard to leak from the heating roller 7, it hardly affects the formation of the electrostatic latent image. In addition, this wall surface 21c can be applied to the caps of the above-described first to third embodiments.

[0040]

As described above, according to the present invention,
Since the minimum space distance with respect to the insulation can be obtained by the cap, noise and leakage can be prevented, and a safe fixing device without malfunction can be provided.

Further, since the length of the halogen heater can be reduced, the size of the fixing device can be reduced. Further, since the number of parts can be reduced, cost can be reduced.

Further, power consumption of the fixing device can be suppressed.

[Brief description of the drawings]

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

FIG. 2 is an enlarged cross-sectional view of a main part on one end side of the fixing device of FIG. 1;

FIGS. 3A and 3B are a front view and a side view of the cap of FIG.

FIG. 4 is an enlarged cross-sectional view of a main part on the other end side of the fixing device of FIG. 1;

FIG. 5 is an enlarged sectional view of a main part of a fixing device according to a second embodiment of the present invention.

FIG. 6 is an enlarged sectional view of a main part of a fixing device according to a third embodiment of the present invention.

FIG. 7 is an enlarged sectional view of a main part of a fixing device according to a fourth embodiment of the present invention.

FIG. 8 is a front view showing a schematic configuration of a conventional fixing device.

9 is an enlarged sectional view of the fixing device shown in FIG.

[10] the arrow X ₁ plan view of the heating body of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Fixing device 6 ... Halogen heater (heating element) 6a, 6b ... Electrode 6c ... Jacket 6d ... Filament 6e, 6f ... Base 6g, 6h ... Crimping member 6i, 6j ... Conductive wire 7 ... Heating roller 9a, 9b ... Bearing 11: Gear 14: Elastic member 15: Power drive source 16: Lead wire 16a: Core wire 17a, 17b, 19, 20, 21 ... Cap 18a, 18b: Locking ring

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroshi Kataoka 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Hiroaki Sakai 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon F term in reference (reference) 2H033 AA42 BB21 BB37 3K058 AA16 AA46 BA18 DA02 DA11 GA06

Claims (4)

[Claims] 1. A fixing device comprising: a power supply unit; and a cylindrical heating roller rotatably supported by enclosing a heating element connected to the power supply unit via electrodes provided at both ends. A fixing device, wherein a cap made of a heat-resistant electrically insulating material is provided on at least one end of the heating roller. 2. The fixing device according to claim 1, wherein a gear for transmitting a driving force to the heating roller is formed in a part of the cap. 3. The fixing device according to claim 1, wherein the cap is disposed between the heating roller and a supporting member that rotatably supports the heating roller. 4. The fixing device according to claim 1, wherein an outer end portion of the cap has a wall extending toward a center in a radial direction.