JPH0473797B2 - - Google Patents

Description

[Detailed Description of the Invention] [Object of the Invention] The present invention relates to a heat fixing device, and in particular, it does not require a large space for supplying heating current to a 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]

BACKGROUND ART Electrophotographic copying devices and copying devices and printer devices that utilize electrostatic photography perform visualization using toner, but in the final step, the toner must be fixed on a toner transfer member such as a sheet of paper. 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 and conveyed between the heating roller 3 and a pressure roller 4. 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 usually 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 180g/mm, and if the heating roller 3 is made of metal such as aluminum or stainless steel, it has enough pressure to withstand the pressure of the pressure roller 4. 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 an object of the present invention is to provide a heat fixing device which is suitable for reducing the size and cost of copying machines and printers by minimizing the portion that protrudes from the effective width of the heat roller. purpose.

[Summary of the invention]

The gist of the present invention is that a sliding member for supplying a heating current from a power source to a heating roller heating element via a conductive part is provided inside a bearing that supports both ends of the heating roller;
The point is that the conductive part and the sliding member are gathered and housed in the same area.

[Embodiments of the invention]

Embodiments of the present invention will be described below 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,
Reference numeral 21 is a cylindrical core obtained by extrusion molding ceramic raw material powder mainly composed of alumina, and a paste made by kneading fine powders of tungsten, molybdenum, manganese, etc. with an organic binder on the surface of the core 21. The heating element 22 is formed by printing in a spiral shape using a thick film method such as printing. The thickness, width, length, and shape of the heating element 22 are appropriately determined so as to obtain a heating resistance value necessary for fixing the toner image.
Heat the core 21 on which the heating element 22 is printed to 1300°C to 1700°C.
Sinter and integrate in a reducing atmosphere at ℃. After sintering and integrating, conductive parts 23 are formed on both end surfaces of the core body 21.
A heating roller is formed by forming a thin coating layer made of silicone rubber, fluororesin, or the like to prevent offset on the portion where the heating element 22 is provided. 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 constituting 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. Sliding members 30 and 31 are provided inside the bearings 26 and 27 that support both ends of the heating roller 3, respectively, so that they slide in contact with the conductive parts 23 and 24, and lead wires 32 and 33 are connected to the power supply. Through the sliding member 3
A heating current is supplied to the heating element 22 through 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 DD' 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. At the upper part of the main body 27b, there is a storage section 27C for storing the sliding member 31.
b and the collar 27a are integrally provided. A sliding member 31 is pressed by a spring 34 and stored in the internal space of the housing portion 27C so that the bottom surface of the sliding member 31 slides in contact with the upper surface of the conductive portion 24. Further, a lead wire 33 is provided on the upper part of the sliding member 31.
One end is electrically connected so that it can be connected to a power source. 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 a heat-resistant and wear-resistant insulating material, the conductive parts 23, 24 and the sliding members 30, 31 are wrapped in the insulating material, which is safe and prevents electrical leakage. There will be no worries, and reliability will increase.

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 according to 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 . Bearing 4
A bearing 45 is integrally provided in the upper part of the storage part 45a for storing the sliding member, and the space in the storage part 45a is pressed by springs 48, 49, and the sliding member contacts the conductive parts 42, 43. sliding members 47, 4
6 is stored. Further, a wall 45c is provided between the springs 48 and 49.

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 addition, in Figure 8,
Although the length F' exceeding the effective width of the heating roller 3 is larger than F in the drawing, the sliding member 4
Since 7 and 46 are made small, the housing portion 45a of the bearing 45 can also be made small, and the size of F' does not become so large. Further, the structure of the bearing 45 is also
As shown in the figure, there may be two storage sections 45a and 45b, and the sliding members 47 and 46 may be stored in the respective storage sections 45a and 45b.

In the above embodiment, a heating roller 3 having a ceramic core 21 was described. Even with a heating element 2, a conductive part for supplying heating current to the heating element 2 is provided on the pipe-shaped roller 1, and a sliding member that slides in contact with the conductive part is housed in the bearing 6. In this way, the portion of the pipe-shaped roller 1 that protrudes beyond its effective width can be made smaller.

〔Effect of the invention〕

As explained above, in the heat fixing device according to the present invention, since the sliding member is housed inside the bearing that supports the heating roller, the portion protruding from the effective width of the heating roller can be reduced, and the device can be made more compact. ,
It is highly effective in reducing component costs and improving reliability.

[Brief explanation of drawings]

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
is the core material if it is made of ceramic, 22 is the heating element, 2
3, 24 are conductive parts, 26, 27 are bearings, 30, 3
1 is a sliding member, 41 is a heating element, 42 and 43 are conductive parts, 44 and 45 are bearings, and 46 and 47 are sliding members.

Claims (1)

[Claims] 1. Consisting of a heating roller having a heating element electrically connected to a conductive part, and a pressure roller provided opposite to the heating roller, and between the heating roller and the pressure roller. In a heat fixing device that pinches and conveys a sheet having an unfixed image, a conductive part electrically connected to the heating element of the heating roller is provided at one end or both ends of the heating roller, and the heating roller is brought into contact with the conductive part. A heating fixing device characterized in that a sliding member that supplies heating current from a power source to the heating element through the conductive portion is housed inside one or both of a pair of bearings that rotatably support both ends of the heating roller. Device.