JPH0326530Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Subject of the Invention] The present invention relates to a heat fixing device, and in particular, it does not take up a large space to supply heating current to the heating roller heating element, and is suitable for downsizing the device and improving reliability. The present invention relates to a heat fixing device.

[Background of the invention] Electrophotographic copying devices and copying devices and printer devices that use electrostatic photography use toner to visualize images, but in the final process, the toner is fixed onto a toner transfer member such as a sheet of paper. There must be. Generally known fixing methods include a method in which the toner is fixed to the transfer member by pressure, a method in which the toner is fused by heat, and a method in which the toner is fused to the transfer member by a combination of the two.

As shown in FIG. 1, bearings 5 and 6 are commonly used as a so-called pressure + heating method that combines both methods of fixing the toner to the transfer member using pressure and fusing it using heat.
A heating roller 3 has a structure in which a heating element 2 such as a heating lamp is provided inside a pipe-shaped roller 1 supported at both ends thereof, and a heating roller 3 provided opposite to the heating roller 3 and supported at both ends by bearings 7 and 8. There is a heat fixing device that includes a pressure roller 4. In this heat fixing device, a heating current is supplied from a power source to both ends of a heating element 2 to heat a heating roller 3, and a sheet having an unfixed image is sandwiched between the heating roller 3 and a pressure roller 4 and conveyed. By doing so, the toner of the unfixed image is melted onto the sheet.

In addition, as the same pressure + heating method, as shown in FIG. A heating roller 3 has a structure in which a thin coating layer made of silicone rubber, fluororesin, etc. for preventing offset is formed on the heating roller 3, and conductive parts 11 and 12 are provided at both ends of the heating roller 9. There is also a heat fixing device having a structure including a pressure roller 4 which is provided facing each other and whose both ends are supported by bearings 15 and 16. In this heat fixing device, the heating element 10 is
Using the sliding members 17 and 18 from the power source via the conductive parts 11 and 12 whose both ends are electrically connected,
Supply heating current to heat roller 3 and pressure roller 4
By conveying a sheet having an unfixed image between them, the toner of the unfixed image is melted onto the sheet.

In the heat fixing device having the above structure,
The heating roller 3 is normally pressed by an elastic member (not shown) such as a spring. Therefore, heating roller 3
The effective length range is the contact length with the pressure roller 4 or a slightly shorter range. In the case of a heat fixing device, the part protruding from this effective length range, that is, the heating element 2 in FIG.
Pressure roller 4 from a sliding member that supplies heating current to
The distances A and A' from the end surface of the heating roller 3 to the end surface of the pressure roller 4 in FIG. Are suitable. However, the conventional heat fixing device has the drawback that this portion is large and becomes an obstacle to miniaturization.

Further, in FIG. 2, conductive parts 11 and 12 are provided between the effective length range of the heating roller 3 of bearings 13 and 14 that support the heating roller 3, and the length of the heating roller 3 is increased accordingly. is getting longer. Normally, the pressing force of the pressure roller 4 is around 180 g/mm, and if the heating roller 3 is made of metal such as aluminum or stainless steel, it can withstand the pressure of the pressure roller 4 sufficiently. It has a rigidity of However, if the roller is made of a fragile material such as ceramic, and the portions B and B' protruding from the pressure roller 4 are long, it may not be able to withstand the bending moment and may be damaged during operation. Also, if the total length of the heating roller 3 is longer than the effective width,
When expensive materials such as ceramics are used, there is also the disadvantage that the cost of parts increases.

[Purpose of the invention] The present invention has been made in view of the above-mentioned points, and is a heat fixing device that minimizes the portion protruding from the effective width of the heating roller and is suitable for downsizing and lowering the cost of copying machines and printers. The purpose is to provide

[Summary of the invention] The main point of the invention is that it consists of a heating roller having a heating element and a pressure roller provided opposite to the heating roller, and that an unfixed image is formed between the heating roller and the pressure roller. In a heat fixing device that fixes a sheet while holding and conveying the sheet, a conductive part electrically connected to the heating element of the heating roller is formed in a band shape around one or both ends of the heating roller, and both ends of the heating roller are rotated. A conductive part that slides into contact with each of the band-shaped conductive parts is provided on the inner peripheral surface of one or both of the freely supported two bearings in contact with the heating roller, and a heating current is supplied from a power source to the conductive part formed on the bearing. The invention is characterized in that it has a means for doing so.

[Embodiments of the invention] Hereinafter, embodiments of the invention will be described based on the drawings.

FIG. 3 is a perspective view showing a heating roller used in the heating fixing device according to the present invention. In the same figure,
For example, 21 is a cylindrical core obtained by extrusion molding ceramic raw material powder containing alumina as a main component, and fine powder of tungsten, molybdenum, manganese, etc. is kneaded with an organic binder on the surface of the core 21. The heating element 22 is formed by printing the paste in a spiral shape using a thick film technique such as printing. This heating element 22
The thickness, width, length, and shape of the toner image are appropriately determined so as to obtain a low heat generation resistance value necessary for fixing the toner image. Heat the core 21 on which the heating element 22 is printed to 1300℃~
It is sintered and integrated in a reducing atmosphere at 1700℃. After sintering and integrating, conductive parts 2 are formed on both end surfaces of the core body 21.
3 and 24 are provided, and a thin coating layer made of silicone rubber, fluororesin, etc. for preventing offset is formed on the portion where the heating element 22 is provided, thereby forming the heating roller 3. Note that the conductive parts 23 and 24 and both ends of the heating element 22 are electrically connected.

FIG. 4 is a diagram showing the structure of a heat fixing device which is an embodiment of the present invention, and in the same figure, 3 is a third
This is a heating roller shown in the figure, and the heating roller 3 is mounted on a main body 25 of a copying machine or printer with a bearing 2.
6 and 27. A pressure roller 4 is supported at both ends by bearings 28 and 29, and is fixed to the main body 25 of the apparatus.
Further, the pressure roller 4 presses the heating roller 3 with an elastic body (not shown) such as a spring. Inside the bearings 26 and 27 that support both ends of the heating roller 3, conductive parts 30 and 31 each having a shape that slides into contact with the conductive parts 23 and 24 electrically connected to the heating element 22 of the heating roller 3 are provided. The lead wires 32 and 33 are passed from the power source to the conductive members 30 and 31.
A heating current is supplied to the heating element 22 via the conductive parts 23 and 24.

Figures 5 and 6 show the inside of the bearing. Figure 5 is a sectional view taken along the line C-C' in Figure 4, and Figure 6 is a sectional view of Figure 5.
It is a sectional view taken along the line D-D' in the figure. As shown in the figure,
The bearing 27 is composed of a main body 27b and a collar 27a, and the main body 27b is inserted into a bearing mounting hole provided in the device main body 25 and fixed. A conductive portion 24 electrically connected to the heating element 22 is provided on the inner surface of the main body 27b.
A conductive portion 31 having a shape that slides into contact with the conductive portion 31 is provided.
The material used for the bearing 27 is an insulating material such as plastic with excellent heat resistance, and the material used for the conductive part 31 is a copper-based sintered alloy material with excellent conductivity.
Further, the bearing 27 and the conductive portion 31 may be manufactured separately and joined together, or may be manufactured integrally. As an example of integrated manufacturing,
It is possible to use a method such as using ceramic as the material of the bearing 27 and metallizing the inside of the bearing 27.Metallizing the inner periphery of the bearing 27 to form the conductive portion 31. Further, one end of a lead wire 33 is electrically connected to the end of the conductive part 31, and a power source is connected to the heating element 2 through the conductive part 31 and the conductive part 24.
2 can be supplied with heating current.

5 and 6 are diagrams showing the inside of the bearing 27, but the internal structure of the bearing 26 is exactly the same as that of the bearing 27, except that the mounting position is reversed.

By configuring the heat fixing device as described above, the lengths E and E' of the portions protruding from the effective width of the heating roller 3 can be determined from A, A' and B, B' shown in FIGS. 1 and 2. becomes smaller. When the heating roller 3 is made of ceramic material, the bending moment applied to the heating roller 3 is reduced accordingly, and the heating roller 3 is not damaged during operation.
Furthermore, if expensive ceramic is used for the heating roller 3, the size of the heating roller 3 will be reduced accordingly, and the cost of the parts of the heating roller 3 will be reduced. Furthermore, since the bearing is made of heat-resistant and wear-resistant insulating material, the conductive parts 23 and 24 and the conductive parts 30 and 31 are wrapped in the insulating material, so it is safe and there is no need to worry about electrical leakage. This will increase reliability.

FIG. 7 shows a heating roller made of ceramic material manufactured in the same manner as the heating roller used in a heat fixing device constituting another embodiment of the present invention. is printed on the ceramic core 21 in two spiral shapes, the leading end 41a is short-circuited, and the rear ends 41b and 41c are printed on the ceramic core 21.
A heating element 41 is formed by leading to one end of the heating element 41, and two conductive parts 42 and 43 are provided for supplying heating current to the heating element 41.
1, the conductive portion 43 and the terminal 41c are electrically connected.

FIG. 8 is a diagram showing the structure of a heat fixing device according to another embodiment of the present invention, in which the heating roller 3 is supported by bearings 44 and 45 at both ends of the heating roller shown in FIG. It is fixed at 25. Two conductive parts 46 and 47 are provided on the inner surface of the bearing 45 and have a shape that makes sliding contact with the conductive parts 42 and 43, respectively. The material used for the bearing 45 is the material used for the bearing 2.
7, the conductive parts 42 and 43 are made of an insulating material such as plastic with excellent heat resistance.
Similarly, a copper-based sintered alloy material with excellent conductivity is used. Further, as in the case of the bearing 27 and the conductive part 31, the bearing 45, the conductive part 46, and the conductive part 47 may be manufactured separately and joined together, or the bearing 45 may be made of, for example, a ceramic material, and the The conductive portion 46 and the conductive portion 47 may be provided on the inner surface of the bearing 45 by metallization processing, respectively. One end of a lead wire 48 and a lead wire 49 are electrically connected to the ends of the conductive portion 46 and the conductive portion 47, respectively, so that a heating current can be supplied to the heating element 41 from a power source. FIG. 9 is an enlarged sectional view showing the structure of the bearing 45.

By configuring as described above, the lengths F and F' extending beyond the effective width of the heating roller 3 are reduced as in the case of FIG. 4. In addition, since the power supply parts such as the wiring that supplies power to the heating roller 3 can be concentrated on one side, it is convenient for the layout of the power supply parts, etc., and is further useful for miniaturization.

In the above embodiment, a heating roller 3 having a ceramic core 21 was described. Even with a heating element 2, if a conductive part for supplying heating current to the heating element 2 is provided on the pipe-shaped roller 1, and a conductive part that slides in contact with the conductive part is provided on the inner surface of the bearing 6, The portion protruding from the effective width of the pipe-shaped roller 1 can be made smaller.

[Effects of the invention] As explained above, according to the invention, a conductive part electrically connected to the heating element of the heating roller is formed in a band shape around one end or both ends of the heating roller,
Since a conductive part that comes into sliding contact with each of the band-shaped conductive parts is provided on the inner circumferential surface of one or both of the two bearings that rotatably support the heating roller in contact with the heating roller, the effectiveness of the heating roller can be increased. Since the width of the protruding portion can be further reduced, an excellent effect can be obtained in that a heat fixing device suitable for miniaturization of the device can be provided.

In addition, since the portion protruding beyond the effective width of the heating roller is small and there is a flow, for example, if the heating roller body is made of an expensive and brittle material such as ceramic,
Not only is the price lower, but the shorter heating roller also increases resistance to bending moments.

[Brief explanation of the drawing]

1 and 2 are diagrams showing the structure of a conventional heat fixing device, FIG. 3 is a perspective view showing a heating roller used in a heat fixing device according to an embodiment of the present invention, and FIG. 4 is a diagram showing the structure of a conventional heat fixing device. FIGS. 5 and 6 are diagrams showing the internal structure of a heating roller bearing, and FIG. 7 is a diagram showing the structure of a heat fixing device according to another embodiment of the present invention. A diagram showing a heating roller to be used,
FIG. 8 is a diagram showing the structure of a heat fixing device according to another embodiment of the present invention, and FIG. 9 is a diagram showing the internal structure of a bearing. In the figure, 3 is a heating roller, 4 is a pressure roller, 21
2 is a core material made of ceramic; 22 is a heating element;
3, 24 are conductive parts, 26, 27 are bearings, 30, 3
1 is a conductive part, 41 is a heating element, 42 and 43 are conductive parts, 44 and 45 are bearings, and 46 and 47 are conductive parts.

Claims (1)

[Claims for Utility Model Registration] A sheet consisting of a heating roller having a heating element and a pressure roller provided opposite to the heating roller, on which an unfixed image is formed between the heating roller and the pressure roller. In a heat fixing device that fixes images while holding and conveying the heating roller, a conductive part electrically connected to a heating element of the heating roller is formed in a band shape around one or both ends of the heating roller, and both ends of the heating roller are Rotatably supported 2
A conductive part that slides into contact with the band-shaped conductive part is provided on the inner circumferential surface of one or both of the bearings that is in contact with the heating roller, and means is provided for supplying heating current from a power source to the conductive part formed in the bearing. A heat fixing device featuring: