JPH06318007A - Heating device - Google Patents

Abstract

PURPOSE:To stably assure the conducting state of an electrically conductive part by forming a conductive member in such a manner that its surface has a shape to ununiformalize the surface pressure of the surface in contact with a conductive surface. CONSTITUTION:Conductive silicone rubber 20 as the conductive member is formed by mixing a carbon black with solid silicone rubber to assure about <=10<8>OMEGA.cm volumetric resistivity and to have an electrical conductivity and is provided in tight contact with the end face of a rubber roller insert 5b by inserting the rubber onto an arbor 5a on one end side of a press roller 5. A carbon contact 14 is brought into pressurized contact with the metallic arbor 5a of the press roller 5 by the elasticity of a metallic leaf spring 21 and this metallic leaf spring 21 is fixed to the side plate of a device chassis 6. The outer peripheral shape of the conductive silicone rubber 20 is knurled. As a result, the surface pressure between the conductive primer layer 4b of a film 4 and the conductive silicon rubber 20 is nonuniform at the peak parts of the knurling and the parts exclusive thereof and, therefore, the formation of the lubricating film of grease is suppressed.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to heating devices.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as an electrophotographic copying machine, a printer or a facsimile, an unfixed toner image formed and carried on a recording material by an image forming process means so as to correspond to desired image information. A heating roller system is generally used as a heating device for heating and fixing the film, but recently, a film heating system heating device has been put into practical use.
This heating device is disclosed in JP-A-63-313182, JP-A-1-263679, and JP-A-2-157878.
As described in Japanese Patent Application Laid-Open No. 4-44075-44083, etc., a heat-resistant film as a heating member is pressed against a heater (heating member) by a pressure member to run, and the heat-resistant film is sandwiched. The recording material is introduced into the pressure contact nip part (fixing nip part) formed by the heater and the pressure member so that it adheres to the heat-resistant film and passes through the fixing nip part together with the heat-resistant film, so that heat from the heater can be kept It is applied to a recording material through a film to heat and fix an unfixed toner image on the surface of the recording material.

In such an apparatus, Japanese Patent Application No. 4-3 is used.
As described in No. 61592, a heat-resistant film as a heating member and a pressure roller as a pressure member are electrically connected and grounded. That is, as shown in FIG. 8, a conductive surface 4b capable of electrical conduction is formed on a part of the outer peripheral surface of the heat resistant film 4, and a part of the pressure roller 5 facing the conductive surface 4b is also made of silicone rubber. The conductive member 30 is made of fluororubber, sponge rubber or the like, and is electrically connected by the contact between the conductive surface 4b and the conductive member 30, and is grounded through the core metal 5a of the pressure roller 5.

This is because the heat resistant film 4 and the pressure roller 5 are charged and disturb the unfixed toner image on the recording material P,
This is to prevent image disturbance due to attraction or the like, and charged electric charge to leak to the ground portion to generate noise, which causes malfunction of the device.

By the way, the heat-resistant film 4 is disposed so as to come into contact with the pressure roller 5 and to be driven to rotate, and slides on the film guide 1 and the heater 3. In order to reduce the amount, heat resistant fluorine grease is applied to the inner surface of the film. This fluorine grease forms a lubricating film between the inner surface of the film and the heater 3 and the film guide 1 so that the film 4 can be smoothly rotated.

[0006]

However, in the above-mentioned conventional example, the fluorine grease heated by the heater 3 and having improved fluidity exudes from the end portion of the film 4,
Wrap around the outer surface of the film. As a result, as shown in FIG. 9, the fluorine grease G sometimes formed a lubricating film between the film outer peripheral conductive surface 4b and the conductive rubber 30 and was electrically insulated.

An object of the present invention is to solve the above problems and to stabilize the conductive state of the electrically conductive portion in a film type heating device having an electrically conductive portion on the outer peripheral surface of the heat resistant film and the pressure roller. The object is to provide a heating device that can be secured.

[0008]

According to the present invention, the above object is achieved by providing a heating member slidably disposed on at least a part of an outer peripheral surface of which an electrically conductive surface is formed. A heating member, and a pressing member that is rotatably arranged while pressing the heating member into pressure contact with the heating member and has a conductive member at a position facing the conductive surface, and is formed via the heating member. In a heating device for sandwiching and transporting a material to be heated at a pressure contact portion between the heating body and the pressure member, the conductive member of the pressure member is a surface at a contact surface with the conductive surface of the heating member. This is achieved by having a surface profile in which the pressure is non-uniform.

[0009]

According to the present invention, the electrically conductive state of the heating member is secured by the contact between the electrically conductive surface of the heating member and the electrically conductive member of the pressing member. Further, the surface of the electrically conductive member is in contact with the electrically conductive surface. Since the surface pressure has a non-uniform shape, even if, for example, the lubricant applied to the heating member leaks to the contact surface, the lubricant or the like forms a film on the contact surface. Is maintained and the electrical continuity is maintained.

[0010]

Embodiments 1 and 2 of the present invention will be described with reference to the accompanying drawings.

<Embodiment 1> First, Embodiment 1 of the present invention will be described with reference to FIGS. In FIG. 1, reference numeral 1 denotes a film inner surface guide member (guide stay member), which has a gutter shape with a substantially semi-circular cross section. The film inner surface guide member 1 is made of, for example, a phenol-based thermosetting resin, and is formed so as to extend long in a direction orthogonal to the transport direction of the recording material P as a heated material.

Reference numeral 3 denotes a heater as a heating body, which is supported in close contact with the lower surface of the film inner surface guide member 1 along the longitudinal direction of the guide member 1. The heater 3 is
As shown in FIG. 2, a ceramic substrate 31 made of alumina or the like having an insulating property, a high heat resistance, and a low heat capacity, whose longitudinal direction is in a direction orthogonal to the conveyance direction of the recording material P, and the front surface side (film sliding) It is a ceramic heater having a low heat capacity as a whole, which basically has a linear or strip-shaped energization heating resistor 32 of silver palladium or the like which is patterned on the surface side) by printing and firing along the longitudinal direction. The energization heating resistor 32
On both end sides, a power supply electrode portion 33 such as Ag is formed on the surface of the substrate 31 so as to be electrically connected to the resistor 32. The power supply electrode portion 33 is provided on the surface of the substrate on which the energization heating resistor 32 is formed. Is a thin surface protective layer 3 made of glass, fluororesin, etc.
4 is provided. Further, a temperature detecting element 35 such as a thermistor and a heat protection means 36 such as a temperature fuse are provided on the back side of the substrate. Therefore, when the power supply connector 9 is fitted to the electrode portions 33 at both ends and AC power is supplied from a power source (not shown), the current-carrying heating resistor 32 generates heat and the entire temperature rises rapidly. Energization to the energization heating resistor 32 is controlled by an energization control system (not shown) that is detected by the temperature detecting element 35, and the temperature of the heater 3 is maintained at a predetermined temperature. If the temperature rises excessively, the heating protection means 36 cuts off the energization.

Reference numeral 4 in FIG. 1 denotes a tube type heat-resistant film (fixing film) loosely fitted onto the film inner surface guide member 1 with the heater 3. The heat resistant film 4 has a heat resistance of 100 μm or less in order to reduce the heat capacity and improve the quick start property.
Uses a film with toner releasability and toughness
Further, as shown in FIG. 3, a polyimide resin layer 4a having a thickness of about 50 μm as an inner layer, a conductive primer layer 4b having a thickness of about 5 μm as an intermediate layer, and a fluororesin layer 4c having a thickness of about 10 μm as an outer layer are provided. It has a layered structure. The resistance value per unit area of the conductive primer layer 4b is 10 ⁸ Ω /
□ It is set below.

Next, 5 is a pressure roller as a pressure member which is pressed against the heater 3 through the film 4, and as shown in FIG. 4, a heat-resistant silicone is concentrically integrated with the metal core 5a. The rubber roller layer 5b is formed, and the surface thereof is coated with a fluororesin. Also, the core metal 5 of the pressure roller 5
As shown in FIG. 1, both ends of a are the device chassis 6 made of sheet metal.
It is rotatably supported by a bearing 7 attached to a gear 5, and a gear 5c is fixed to one shaft end of the bearing.
The gear 5c meshes with a drive system gear (not shown) of the image forming apparatus main body, and the pressure roller 5 is rotationally driven at a predetermined peripheral speed. Further, the pressure roller 5 is pressed against the heater 3 with a predetermined pressing force by the pressure springs 8 that press the upper surfaces of both ends of the film inner surface guide member 1, respectively, as shown in FIG. A fixing nip N is formed. Therefore, when the pressure roller 5 is driven to rotate, the surface friction of the pressure roller 5 causes the tube-shaped film 4 to closely slide on the surface of the heater 3 and to rotate around the film inner surface guide member 1. It has become so. Since the heat-resistant fluorine grease G is applied to the inner peripheral surface of the heat-resistant film 4, a lubricating film is formed between the inner surface of the film 4 and the heater 3 and the guide member 1 to reduce sliding resistance. Therefore, the smooth rotation drive of the heat resistant film 4 is ensured.

In front of the heat resistant film 4 and the pressure roller 5 arranged as described above, an inlet guide 10 is arranged as shown in FIG. 4, and an image forming process means portion (not shown). The recording material P having the unfixed toner image as the material to be heated carried on the upper surface is guided by the entrance guide 10 and introduced into the fixing nip portion N between the heat resistant film 4 and the pressure roller 5. The recording material P introduced into the fixing nip portion N comes into close contact with the surface of the rotating film 4 and passes through the fixing nip portion N together with the film 4, thereby heating the unfixed toner image on the recording material P with a heater. The thermal energy of 3 is given through the film 4 to heat and fix the toner image. The recording material P after fixing is discharged along a discharge guide 11 arranged behind the film 4 and the pressure roller 5, and the fixing operation is completed.

As described above, since the heat-resistant film 4 and the pressure roller 5 are in sliding contact with each other and further perform the fixing operation in sliding contact with the recording material P, they may be charged and disturb an image or generate noise. is there. Therefore, the heat-resistant film 4 of this embodiment is provided with the conductive primer layer 4b as described above,
Further, by providing the pressure roller 5 with a conductive member so as to be in contact with the conductive primer layer 4b, the charged electric charge is released.

In FIG. 1, reference numeral 20 is a conductive member provided on the pressure roller 5. The conductive silicone rubber 20 as the conductive member is obtained by mixing carbon black in solid silicone rubber to secure a volume resistivity of about 10 ⁸ Ω · cm or less and to obtain conductivity. It is inserted into the core metal 5a on one end side and is provided in close contact with the end surface of the rubber roller layer 5b. The conductive silicone rubber 20 is arranged at a position corresponding to the exposed conductive primer layer 4b as a conductive surface provided on the end portion of the heat resistant film 4, and the outer diameter thereof is outside the rubber roller layer 5b of the pressure roller 5. It is almost equal to the diameter. Therefore, the conductive silicone rubber 20 is pressed against the conductive primer layer 4b on the film 4 side, and thereby rotates integrally with the pressure roller 5 at the peripheral speed equal to the surface speed of the heat resistant film 4.

A carbon contact 14 is attached to the metal core 5a of the pressure roller 5 by the elasticity of the metal leaf spring 21.
The metal plate spring 21 is fixed to the side plate of the apparatus chassis 6 by being pressed into contact with a. Therefore, the electric charge applied to the heat-resistant film 4 is transferred from the conductive primer layer 4b to the pressure roller 5.
Side to the conductive silicone rubber 20, and further from the conductive silicone rubber 20 to the pressure roller core metal 5a via the rubber roller layer 5b, passing through the carbon contact point 14, the leaf spring 21 and the device chassis 6 to the ground. ing.
Similarly, the electric charge of the pressure roller 5 is also the core metal 5a and the carbon contact 1.
4, it has fallen to the ground through the path of the leaf spring 21 and the device chassis 6.

As described above, according to the heating device of this embodiment, the heat resistant film 4 and the pressure roller 5 are prevented from being charged,
It is possible to prevent problems such as image distortion. However, as described above, the heat-resistant fluorine grease G applied to the inner peripheral surface of the heat-resistant film 4 has good flowability when heated by the heater 3, and bleeds at the end portion of the film 4 as shown in FIG. When it is taken out, it adheres to the outer peripheral surface of the film 4 and electrically insulates the film 4.

Therefore, in this embodiment, the outer peripheral shape of the conductive silicone rubber 20 is knurled. As a result, the surface pressure between the conductive primer layer 4b of the film 4 and the conductive silicone rubber 20 becomes non-uniform at the knurled top and other portions as shown in FIG. 5, so that the formation of the lubricating film of the fluorine grease G is suppressed. You can

As described above, according to the present invention, smooth rotation of the film 4 by the fluorine grease G is guaranteed without impairing the charge removing function of the film 4 by the conductive primer layer 4b and the conductive silicone rubber 20. You can

<Second Embodiment> Next, a second embodiment of the present invention will be described with reference to FIGS. 6 and 7. The same parts as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In Example 1, the outer circumference of the conductive silicone rubber was formed into a knurled shape. However, since it is sufficient that a lubricating film is not formed on the contact surface with the film 4, grooves or holes are formed on the outer peripheral surface as shown in FIG. Even if the conductive silicone rubber 20 'and the conductive silicone rubber 20 "having a convex outer peripheral surface as shown in FIG. 7 have non-uniform contact pressure on the contact surface, no lubricating film is formed and stable and reliable conduction is achieved. You can also obtain grooves, holes, protrusions,
It goes without saying that knurling etc. may be provided at the same time.

[0024]

As described above, according to the present invention,
The conductive member of the pressure roller that contacts the conductive surface of the film,
Since the surface shape is such that the contact pressure on the contact surface becomes non-uniform, stable film conduction can be reliably obtained even when a lubricant is applied to the film. Therefore, it is possible to prevent the malfunction of the apparatus due to the image disturbance and the noise due to the charging of the film while ensuring the smooth rotation of the film.

[Brief description of drawings]

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

FIG. 2 is a diagram showing a schematic configuration of a heater in the apparatus shown in FIG.

FIG. 3 is a diagram showing a layer structure of a film in the apparatus shown in FIG.

FIG. 4 is a main cross-sectional view of the device shown in FIG.

5 is a cross-sectional view of a conducting portion in the device shown in FIG.

FIG. 6 is a diagram showing a schematic configuration of a conductive member according to a second embodiment of the present invention.

FIG. 7 is a diagram showing a schematic configuration of another conductive member in Example 2 of the present invention.

FIG. 8 is a diagram showing a schematic configuration of a conventional device.

FIG. 9 is a cross-sectional view of a conducting portion in a conventional device.

[Explanation of symbols]

 3 Ceramic Heater (Heating Body) 4 Heat Resistant Film (Heating Member) 4b Conductive Primer Layer (Conductive Surface) 5 Pressure Roller (Pressurizing Member) 20 Conductive Silicone Rubber (Conductive Member) P Recording Material (Heating Material)

Continued Front Page (72) Inventor Yuzayo 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (2)

[Claims] 1. A heating member which is slidably disposed on a heating body and has a conductive surface which is electrically conductive on at least a part of an outer peripheral surface thereof, and is pressure-contacted to the heating body through the heating member. While being rotatably provided, a pressure member having a conductive member at a position facing the conductive surface is provided, and the pressure contact portion between the heating body and the pressure member formed via the heating member is covered. In a heating device for sandwiching and transporting a heating material for heating, the conductive member of the pressing member has a surface shape such that the surface pressure at the contact surface with the conductive surface of the heating member is non-uniform. Characteristic heating device. 2. The surface shape of the conductive member is knurled,
The heating device according to claim 1, which has a shape such as a groove, a hole, or a protrusion.