JPH10319756A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a cost for a power supplying constitution to a fixing roller. SOLUTION: A power supply cap 24 as a power supply member is provided inward at the end of a self heating type fixing roller 2 having a heat resistor layer 10 on the inner face of a cylindrical core material 4 and a solid power supply brush 30 is thrusted against the power supply cap 24 with a plate spring thrusting member 5. The thrusting member 5 has an approximately V-shaped deformation part, with one end fixed to a plate spring holder 7 and connected to an alternating current 3 via a harness 9. With the approximately V-shaped deformation part, linearly thrusting function similar to that of a coil spring is provided, resulting in the solid power supply brush 30 not to be shifted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device used in an image forming apparatus such as a copying machine, a printer, and a facsimile.

[0002]

2. Description of the Related Art In recent years, energy saving has been advocated in image forming apparatuses such as copying machines, printers, and facsimile machines of the electrophotographic type. One of the methods is a self-heating type fixing roller. ) Has been proposed. In the case of a self-heating type fixing roller, since the roller itself generates heat directly, there is an advantage that the heat efficiency is higher and a high-speed start-up can be achieved as compared with an indirect heating type in which a halogen heater is incorporated. Examples of such a self-heating type fixing roller system include a system in which a heating resistor layer is provided on the outer surface of a cylindrical core material, a system in which the core material itself is a heating element in which a conductor is mixed in ceramics,
There are three main types in which a heating resistor layer is provided on the inner surface of the core material. In any of these methods, in order to start up at high speed, it is preferable to reduce the thickness of the core material in order to reduce the heat capacity of the core material as much as possible. Among these three methods, particularly in a method having a heating resistor layer on the inner surface of a core material, since heat is transmitted through the core material, further reduction in thickness is desired. However, when the thickness is reduced, the strength of the fixing roller is reduced. When a pressure roller is placed opposite to the fixing roller to fix the toner across the paper, if the strength of the fixing roller is weak, the fixing roller will bend or collapse, causing wrinkles or partial paper In some cases, a phenomenon such as deterioration of fixing performance may occur.

As a method for preventing the strength of the fixing roller from lowering and also for supplying power to the fixing roller, a power supply member also serving as a journal is disposed at an end of the fixing roller, and the power supply member for the journal is provided on the circumference of the journal power supply member. There is a method in which power is supplied from an end or a power supply brush or the like. However, although the strength can be obtained by integrating with the journal, the heat capacity of the portion is large, and unless the amount of heat generated on the end side of the fixing roller is increased, the temperature of the end portion cannot be increased and a fixing failure occurs. For this reason, there is a problem that wasteful power is required.

On the other hand, as a method of supplying power from an external power supply to the fixing roller, for example, as shown in FIG.
A ring-shaped power supply member 82 is provided on the outside, and a solid power supply brush 84 is pressed against the power supply member 82 by a leaf spring 83. In the drawing, reference numeral 86 indicates a pressure roller, 88 indicates a temperature sensor, 90 indicates an alternating current, and 92 indicates a triac. In this method, when there is a heating resistor layer on the inner surface of the core material 80, in order to take an energized configuration, it is necessary to connect the heating resistor layer and the power supply member 82 by turning an electrode outside the end of the core material 80. ,
A complicated configuration has to be taken, such as making a hole in the core material 80 itself and connecting it to the power supply member 82, or passing electricity through the core material 80.

As another power supply method, there is a method shown in FIGS. In FIG. 9, a solid power supply brush 84 is pressed against the end surface of the fixing roller 80 by a leaf spring 83, and
0, a ring-shaped power supply member 85 is provided on the inner surface of the fixing roller 80.
The solid power supply brush 84 is pressed against the inner peripheral surface of the power supply member 85 by a leaf spring 83. 9 and 1
At 0, reference numeral 87 indicates a bearing.

In each of these power supply methods, since the solid power supply brush is located on the circumference of the power supply member or a member corresponding to the power supply member, the running distance (sliding distance) of the solid power supply brush is long, and abrasion powder is easily generated. . When the abrasion powder is generated, it adversely affects the surface of the fixing roller and electric components inside the apparatus, and sometimes shortens the service life or causes failure.

[0007]

Therefore, the present applicant has
In Japanese Patent Application No. 9-6633, there has been proposed a self-heating type fixing roller capable of solving the above-mentioned problems associated with the thinning of the fixing roller and the problem of abrasion powder without increasing the cost with a simple configuration. This is because the length of the heating resistor layer provided on the inner surface is positioned inward in the longitudinal direction of the core material, and a conductive power supply member is inserted from both ends of the core material to form the heating resistor layer. And the power supply member is provided so as to be located inward in the longitudinal direction from the end of the core material, and a solid power supply brush is provided at the roller rotation axis portion of the power supply member by a coil spring. It is configured to be pressed and contacted in the direction. According to this configuration, strength in thinning is obtained by the positional reinforcing action of the power supply member, and wear powder can be suppressed by a configuration in which the solid power supply brush is brought into contact with the roller rotation axis of the power supply member.

When considering a pressing member for pressing the solid power supply brush against the power supply member from the viewpoint of cost, a leaf spring is more advantageous than a coil spring because the support structure of the pressing member is simpler. is there. However, a configuration in which the power supply member is located inside the roller end portion (Japanese Patent Application No. 9-66).
No. 33), the pressing force must be applied linearly along the axis of the roller, which is difficult with the conventional leaf spring structure as shown in FIGS. Conventionally, an N-shaped shape as shown in FIGS. 11 and 12 has been known as a shape in which a leaf spring can have a linear pressing function like a coil spring. As shown in FIGS. 11A and 12A, one end (left side in the drawing) of each of the leaf springs 100 and 101 is fixed to the apparatus main body side, and the solid power supply brush 102 is fixed to the free end. I have. FIG. 11 (a), FIG.
(A) shows the natural length of each of the leaf springs 100 and 101.

When the fixing roller is set at a predetermined position, as shown in FIG. 11B and FIG.
0 and 101 are deformed, and the solid power supply brush 102 comes into contact with a power supply member 104 in the fixing roller 103 while receiving an elastic force. However, the solid power supply brush 102 is displaced with the deformation of each leaf spring 100, 101, and the power supply member 10
5 does not correspond to the center of rotation of the fixing roller 103. If it does not correspond to the rotation axis, the sliding speed increases, and wear powder is generated. For this reason, it is necessary to shift the fixing positions of the leaf springs 100 and 101 in advance in accordance with the amount of displacement of the solid power supply brush 102, which is troublesome. Further, since the fixing roller expands and contracts by about 1 to 2 mm in the longitudinal direction due to a change in temperature from room temperature to about 190 ° C., it is difficult to always press the solid power supply brush to the rotational axis position where the wear powder is least generated. Met.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fixing device that can solve the problem when a leaf spring-shaped pressing member is used in a configuration for supplying power to a fixing roller. Also, the present invention
It is an object of the present invention to provide a fixing device that can solve the problem associated with the thinning of the self-heating type fixing roller and the problem when using a leaf spring-shaped pressing member.

[0011]

In order to achieve the above object, according to the first aspect of the present invention, there is provided a fixing roller having a power supply member, wherein the power supply member is provided with a terminal member connected to an external power supply in the form of a leaf spring. In the fixing device in which the pressing members are brought into pressure contact with each other, the deformed portion of the pressing member is formed to have a substantially V-shaped cross section.

According to a second aspect of the present invention, in a fixing device provided with a self-heating type fixing roller in which a heating resistor layer is formed on an inner peripheral surface of a cylindrical core material, the heating resistor layer is provided on both sides thereof. An end portion is formed with a length located inward in the longitudinal direction of the core material, and a conductive power supply member is inserted from both ends of the core material and is in contact with both ends of the heating resistor layer, and The power supply member is provided so as to be located inward in the longitudinal direction from an end of the core material, and the power supply member has a terminal member connected to an external power supply by a leaf spring-shaped pressing member. The pressing member is pressed in the axial direction, and the deformed portion of the pressing member is formed to have a substantially V-shaped cross section.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 4, the fixing device includes a self-heating type fixing roller 2 which is rotatably supported at both ends thereof on a device side plate (not shown) via bearings 20; A pressure roller 18 is provided which is pressed against the mold fixing roller 2 and rotates. Although not shown, a release layer made of PTFE (polytetrafluoroethylene) is formed on the outer peripheral surface of the core material 4. The self-heating type fixing roller 2 is energized by a leaf spring-shaped pressing member 5 connected to an AC 3 as an external power supply.
This will be described later. The self-heating type fixing roller 2
As shown in FIG. 1, a cylindrical heating element 4 made of aluminum, and a heating resistor made of a silver alloy formed on an inner peripheral surface of the heating element 4 via an insulating layer made of a non-conductive resin (not shown). A layer 10, a power supply cap 24 as a conductive power supply member having an inner lid shape having a U-shaped cross section fixed by being inserted into both ends of the core material 4 and a holder 26 holding the power supply cap 24. It is configured.

The heating resistor layer 10 is formed to have a length located inside the core member 4 in the longitudinal direction.
4 is also provided so as to be located inside the end of the core material 4. Specifically, the power supply cap 24 is provided inside the bearing 20, thereby preventing a reduction in strength due to the thinning of the core material 4. As shown in FIG. 3, the power supply cap 24 is provided with a power supply contact portion 24a projecting outward in the axial direction of the core member 4 at a central portion by means such as drawing. The holder 26 is formed of a non-conductive and heat-resistant material, and includes a small-diameter portion 27 into which the power supply cap 24 is fitted, and a large-diameter portion 28 fixed to an end of the core 4. ing. An opening 27 for exposing the power supply contact portion 24a of the power supply cap 24 to the outside is formed in the small diameter portion 27.
a is formed.

As shown in FIG. 3C, the power supply cap 2
After assembling the holder 4 and the holder 26, the core member 4 is, for example, shrink-fitted and fixed. When the power supply cap 24 is held by the holder 26, the cylindrical side surface 24 b (which is also a contact portion with the heating resistor layer 10) determines the attitude with respect to the core member 4, as compared with the case where the power supply cap 24 is fixed alone.
Is substantially longer, ie, the holder 26
Since the side surface 28a of the large diameter portion 28 is added, it is possible to prevent a manufacturing error such as the oblique mounting of the power supply cap 24, and to equalize the quality accuracy of the self-heating type fixing roller 2 and the reliability. Can be achieved. Further, since the abrasion powder generated when the solid power supply brush is brought into contact with the power supply contact portion 24a of the power supply cap 24 accumulates in the non-conductive holder 26, the core material 4 and the power supply cap 24 are separated by bridging the wear powder. It is possible to prevent accidents such as electrical leakage between the spaces. Further, since the power supply contact portion 24a is protruded, it is possible to prevent the solid power supply brush from hitting a portion 27b of the holder 26 perpendicular to the roller axis and causing a contact failure. From such a viewpoint, it is desirable that the amount of protrusion of the power supply contact portion 24a be equal to or greater than the thickness of the holder 26. Also, this power supply contact portion 24a
Contributes to the improvement of the strength of the power supply cap 24 itself, and the holder 2
Even when there is no 6, the contact with the solid power supply brush is improved.

A stopper 2 projecting in the radial direction of the core 4 is provided on the rear end side in the insertion direction of the power supply cap 24 into the core 4.
9 are formed. When the holder 26 in which the power supply cap 24 is fitted is inserted into the core 4, the stopper 29 abuts against the end face of the core 4, thereby positioning the power supply cap 24 with respect to the core 4. Therefore, it is possible to prevent the power supply cap 24 from being inserted too much. In other words, it is possible to suppress the fluctuation of the position of the power supply cap 24 at both ends of the core member 4, and to make the quality accuracy of the self-heating type fixing roller 2 uniform. Can be achieved. The shape of the stopper 29 may be annular or partial. Stopper 2
The protrusion amount in the radial direction of 9 is set so as not to protrude from the outer diameter of the core member 4, so that the insertion of the bearing 20 is not hindered.

As shown in FIG. 1, a leaf spring-like pressing member 5 is provided.
Is fixed to a leaf spring holder 7 made of an insulating member fixed to the apparatus main body. A solid power supply brush 30 as a terminal member is fixed to a free end of the pressing member 5.
The solid power supply brush 30 is pressed against the power supply contact portion 24 a of the power supply cap 24 by the restoring force of the pressing member 5. A through hole 7 a is formed in the leaf spring holder 7, through which a harness 9 from the alternating current 3 passes and is connected to a fixed end of the pressing member 5. A solid power supply brush 30 is provided on the power supply cap 24.
When the contact is made, the heating resistor layer 10 is energized, and the heating resistor layer 10 generates heat.

The pressing member 5 in the form of a leaf spring in this embodiment
As shown in FIG. 2 (a), the fixing device includes a fixing piece 5a fixed to the leaf spring holder 7, a brush supporting piece 5b to which the solid-state power supply brush 30 is fixed, and a deforming portion 5c located therebetween. Have been. The deformed portion 5c is formed in a substantially V-shape in cross-sectional shape, and has an M-shape in cross-sectional shape or side shape as a whole. The brush support piece 5b is perpendicular to the roller axis S. When the elements of the deformable portion 5c which is formed in a substantially V-shape and 5c _1, 5c _2, 5
c ₁ and 5c ₂ have the same length and are symmetric with respect to a straight line H parallel to the brush supporting piece 5b. When the self-heating type fixing roller 2 is set at a predetermined position so as to be energized, FIG.
As shown in (b), even when the deformed portion 5c is compressed in the axial direction of the roller, the solid power supply brush 30 does not shift from the roller axis S. This is because the respective elements 5c ₁ and 5c ₂ of the deformed portion 5c are symmetrical with each other, so that their displacements are offset.
Therefore, since the solid power supply brush 30 is always positioned at the position of the roller axis S, electric contact with the power supply contact portion 24a does not deteriorate, and even if the power supply contact portion 24a is not formed in a convex shape. Since the solid power supply brush 30 is located at the center of rotation of the roller, the generation of wear powder can be suppressed to a minimum.

In other words, the shape of the pressing member 5 has a brush support piece 5b perpendicular to the roller axis S, and a cross-sectional shape or a side shape between the brush support piece 5b and the fixed piece 5a. This is a shape having a symmetrical substantially V-shaped deformed portion 5c. Therefore, the present invention is not limited to the complete V-shape as described above, and various shapes as shown in FIG. 5 can be adopted. FIG. 6 shows a power supply configuration using the pressing member 5 shown in FIG. The pressing member 11 shown in FIG.
The deformed portion also has a symmetrical shape with a chevron shape, but in such a shape, the number of bending times is large and it is difficult to configure, and the solid power supply brush 30 moves up and down in the drawing like a normal compression spring. It is not preferable because it is easy.

In the above-described embodiment, an example of the power supply configuration using the leaf spring-shaped pressing member 5 in the configuration in which the power supply cap 24 serving as the power supply member is located inside the end of the core member 4 has been described. However, the same operation and effect can be obtained in any case where a leaf spring, which is inexpensive compared to a coil spring, is used as a pressing member for pressing linearly. Further, the present invention is not limited to the self-heating type fixing roller, and can be similarly applied to power supply to a conventional fixing roller including a halogen lamp.

[0021]

According to the first aspect of the present invention, a terminal member connected to an external power supply by a leaf spring-like pressing member having a deformed portion having a substantially V-shaped cross section is used as a power supply member on the fixing roller side. , So that a linear pressing function similar to that of a coil spring can be obtained even though it has a leaf spring configuration, and the cost of the power supply configuration in the fixing device can be reduced by simplification of the configuration. be able to.

According to the second aspect of the present invention, in the power supply structure of the self-heating type fixing roller in which the power supply member is located inside the end portion of the core material, the leaf spring having a deformed portion having a substantially V-shaped cross section is provided. Although the configuration using a pressing member in the shape of a plate spring, a linear pressing function in the axial direction of the roller similar to the coil spring can be obtained even though the configuration is a leaf spring, and thus the configuration in the fixing device can be simplified. The cost of the power supply configuration can be reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a power supply component to a self-heating type fixing roller constituting a fixing device according to the present invention.

FIGS. 2A and 2B are schematic cross-sectional views showing a deformation operation of a leaf spring-shaped pressing member in the power supply configuration shown in FIGS. 1A and 1B, wherein FIG. 2A shows a case of a natural length, and FIG. Is the case.

FIG. 3 is an assembly diagram of a power supply configuration of a self-heating type fixing roller;
(A) is an exploded perspective view, (b) is a cross-sectional view, and (c) is a cross-sectional view in a state where a power supply cap and a holder are assembled.

FIG. 4 is a schematic perspective view of a fixing device according to the present invention.

FIG. 5 is a side view showing a modified example of a leaf spring-shaped pressing member.

FIG. 6 is a side view showing a mounting state of the pressing member shown in FIG. 5 (d).

FIG. 7 is a side view showing an inappropriate example of the pressing member.

FIG. 8 is a perspective view showing a conventional power supply configuration.

FIG. 9 is a schematic sectional view showing another conventional power supply configuration.

FIG. 10 is a schematic sectional view showing still another conventional power supply configuration.

FIG. 11 is a schematic sectional view showing a deformation operation of a conventional N-shaped pressing member.

FIG. 12 is a schematic sectional view showing a deformation operation of another conventional N-shaped pressing member.

[Explanation of symbols]

 2 Self-heating type fixing roller (fixing roller) 3 AC as external power supply 4 Core material 5 Pressing member 5c Deformation part 10 Heating resistor layer 24 Power supply cap as power supply member 30 Solid power supply brush as terminal member

Claims (2)

[Claims] 1. A fixing device comprising a fixing roller having a power supply member, wherein a terminal member connected to an external power supply is brought into press contact with the power supply member by a leaf spring-shaped pressing member. Is a fixing device having a substantially V-shaped cross section. 2. A fixing device comprising a self-heating type fixing roller in which a heating resistor layer is formed on an inner peripheral surface of a cylindrical core material, wherein both ends of the heating resistor layer are formed at the ends of the core material. A conductive power supply member is inserted from both ends of the core material and is in contact with both ends of the heating resistor layer, and the power supply member is A terminal member connected to an external power supply is provided on the power supply member so as to be located inward in the longitudinal direction from the end of the core material, and is contacted in the axial direction of the core material by a leaf spring-shaped pressing member. And a deformable portion of the pressing member is formed in a substantially V-shaped cross section.