JP4701044B2 - Fixing apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a heat roller type fixing device provided by pressing a fixing roller and a pressure roller, and an electrophotographic image forming apparatus equipped with the fixing device.

In an electrophotographic image forming apparatus, a heat roller type fixing device is often used as a fixing device for fixing a toner image transferred onto a recording sheet. This fixing device has a heat source inside, and a pressure roller and a fixing roller formed on a surface having a releasability with respect to the toner, for example, silicone rubber or fluororesin, and a pressure roller, and the pressure contact between both rollers. The unfixed toner image on the recording paper passing through the nip forming part is heated and pressed to be fixed.
In this heat roller type fixing device, since the surface of the fixing roller and the toner image on the recording paper come into contact with each other under pressure, the thermal efficiency when fusing the toner image on the recording paper is extremely good, and the fixing is performed quickly. This is very effective in a high-speed image forming apparatus.
When recording paper of a small size is continuously fixed compared to the width of the fixing roller (axial direction; length in the longitudinal direction), the heat at the end of the fixing roller outside the sheet passing range is not absorbed by the recording paper, so fixing The temperature at the end in the roller width direction is higher than that at the center of the fixing roller, and the temperature at the end of the pressure roller that is in direct contact with that portion is also higher than that at the center of the pressure roller.
When the temperature detecting member is disposed at the center in the longitudinal direction of the fixing roller, the temperature at the end of the roller is excessively increased, thereby causing early deterioration of the fixing roller and the pressure roller surface layer. In addition, since the heat energy generated from the heating source is also used to increase the temperature of the portion where the recording paper does not pass, the energy efficiency becomes very poor. On the other hand, when the temperature detection member is disposed at the end portion in the longitudinal direction of the fixing roller, the fixing roller temperature at the central portion of the roller (recording paper passage portion) is lowered, so that the fixing property is deteriorated.
As a countermeasure, a technique has been proposed in which a heat transfer member is placed in contact with a part of the surface of the pressure roller to make the temperature of the pressure roller uniform. In this configuration, the heat transfer member is brought into contact with the entire width of the pressure roller. Further, by using a heat pipe roller or an aluminum roller as the heat transfer member, the effect of efficiently uniforming the temperature of the pressure roller is improved.

However, heat pipe rollers and aluminum rollers not only have good heat transfer in the longitudinal direction, but also have good heat transfer in the radial direction and circumferential direction. The amount of heat that escapes (moves) into the atmosphere (near the fixing roller and the pressure roller) also increases. Therefore, the technique of arranging the heat transfer member in contact with a part of the surface of the conventional pressure roller and making the temperature of the pressure roller uniform has the effect of making the temperature distribution in the longitudinal direction of the pressure roller uniform. Although improved, there was a problem that the temperature dropped as a whole, resulting in a decrease in thermal efficiency.
The present invention is based on the premise that the heat transfer member is disposed in contact with a part of the surface of the pressure roller, and the fixing capable of preventing the movement of heat to the atmosphere (near the fixing roller and the pressure roller). An object is to provide an image forming apparatus and an image forming apparatus.

In order to achieve the above object, the invention according to claim 1 comprises a fixing roller, a pressure roller rotating in pressure contact with the fixing roller, and a long-axis roller rotating in contact with the surface of the pressure roller. and the heat transfer member, said heat transfer member on the outer periphery of the resin of the inner heat insulating layer, that have a structure in which laminated outer insulation layer disposed alternately high thermal conductivity material and the low thermal conductivity material in the circumferential direction constant of In the landing apparatus , a heat pipe is inserted into the high thermal conductivity material .
According to a second aspect of the present invention, there is provided a fixing roller, a pressure roller that rotates in pressure contact with the fixing roller, a long-axis roller-shaped heat transfer member that rotates in contact with the surface of the pressure roller, and the heat transfer In the fixing device, the member has a configuration in which an outer heat insulating layer in which a high heat conductivity material and a low heat conductivity material are alternately arranged in the circumferential direction is laminated on the outer periphery of the resin inner heat insulating layer. It is an aluminum-based material, and the low thermal conductivity material is an iron-based material or a resin material .
A third aspect of the present invention, in the fixing device according to claim 1, wherein the high thermal conductivity material is a aluminum-based material, wherein the low thermal conductivity material is characterized in that an iron-based material or a resin material.
According to a fourth aspect of the present invention, in the fixing device according to the first, second, or third aspect, the heat transfer member is configured such that only the low thermal conductivity material region of the outer heat insulating layer contacts the pressure roller when rotation of the pressure roller is stopped. Rotational position control means for controlling the rotational position is provided.
The invention of claim 5, an image forming apparatus equipped with fixing device according to any one of claims 1 to 4, feature.

According to the present invention, in the fixing device in which the heat transfer member in the form of the long-axis roller is disposed in parallel with the surface of the pressure roller that is in pressure contact with the fixing roller, the heat transfer member is heated on the outer periphery of the resin heat insulating layer. Since the conductivity material and the low thermal conductivity material are alternately arranged in the circumferential direction, heat transfer to the atmosphere (near the fixing roller and the pressure roller) can be prevented.
Moreover, when the heat pipe is inserted in the high thermal conductivity material, there is an effect that the temperature distribution in the longitudinal direction of the pressure roller is made more uniform.
In addition, when the pressure roller rotation is stopped, only the low thermal conductivity material region of the heat transfer member is brought into contact with the pressure roller, so that when the pressure roller rotation is stopped, the contact portion with the pressure roller is transferred to the heat transfer member. The heat transfer can be reduced.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram of a fixing device according to an embodiment of the present invention, and FIG. 1 is a front view (a view of a fixing device mounted on the image forming apparatus viewed from the front side of the image forming apparatus), and (2). Is a side view.
A pressure roller 2 whose surface is covered with an elastic material is pressed against the fixing roller 1. The fixing roller 1 incorporates a heater 3, detects the temperature of the fixing roller 1 by a temperature detection member 4 disposed at the longitudinal end of the fixing roller 1, and is controlled to reach a constant temperature by a temperature control device (not shown). The
When the recording paper 5 holding the unfixed image 6 passes through the nip which is the pressure contact portion between the fixing roller 1 and the pressure roller 2, the toner melts and the pressure is applied to fix the unfixed image 6 on the recording paper 5. Is done. The heat transfer member 11 abuts in parallel with the outer periphery of the pressure roller 2 and rotates, so that the temperature distribution of the pressure roller 2 is made uniform when small-size paper is passed. The heat transfer member 11 is in the form of a long-axis roller having a diameter much smaller than that of the pressure roller 2, and the axial direction (longitudinal direction) coincides with the pressure roller 2.
FIG. 2 is a block diagram showing an example of the heat transfer member shown in FIG. The heat transfer member 11 includes a resin-made inner heat insulating layer 12 and an outer heat insulating layer 15 which is arranged on the outer periphery thereof and alternately arranges a high heat conductivity material 13 and a low heat conductivity material 14 in the circumferential direction. Has been.
An example of the high thermal conductivity material 13 is an aluminum material. In addition, examples of the low thermal conductivity material 14 include iron-based materials and resin materials.
Figure 3 is an enlarged diagram showing a real施例heat transfer member shown in FIG. A heat pipe 16 is inserted into a high thermal conductivity material (for example, an aluminum-based material) 13.
4 is a view showing a detection mechanism of the low thermal conductivity material shown in FIGS. 2 and 3, wherein (1) is a front view and (2) is a top view.
The circumferential direction position of the low thermal conductivity material 14 of the heat transfer member 11 is detected by a filler 21 that is arranged at the shaft end of the heat transfer member 11 and rotates synchronously, and a photosensor 22 installed in the vicinity thereof. Accordingly, the rotation of the pressure roller 2 is stopped at a position where the pressure roller 2 and the low thermal conductivity material 14 of the heat transfer member 11 come into contact with each other.
In the present invention, the temperature detection member 4 may be disposed at the center in the longitudinal direction of the fixing roller 1. Further, it can be developed not only in the pressure roller 2 but also in a fixing belt type fixing device.

1 is a configuration diagram of a fixing device according to an embodiment of the present invention. The block diagram which shows one example of the heat transfer member shown in FIG. Enlarged configuration diagram showing the actual施例heat transfer member shown in FIG. The figure which shows the detection mechanism of the low thermal conductivity material shown to FIG. 2, FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fixing roller, 2 Pressure roller, 11 Heat transfer member, 12 Inner heat insulation layer, 13 High heat conductivity material, 14 Low heat conductivity material, 15 Outer heat insulation layer, 16 Heat pipe, 21 Filler (component of rotational position control means) , 22 Photosensor (component of rotational position control means)

Claims (5)

Fixing roller and a pressure roller that rotates in pressure contact with the fixing roller, and the long axis roller-shaped heat transfer member that rotates in contact with the surface of the pressure roller, the heat transfer member is inside insulation resin the outer periphery of the layer, in the constant Chakusochi that have a structure formed by laminating an outer heat-insulating layer disposed alternately high thermal conductivity material and the low thermal conductivity material in the circumferential direction,
A fixing device, wherein a heat pipe is inserted in the high thermal conductivity material . A fixing roller; a pressure roller that rotates in pressure contact with the fixing roller; a long-axis roller-shaped heat transfer member that rotates in contact with the surface of the pressure roller; In the fixing device having a configuration in which the outer heat insulating layer in which the high thermal conductivity material and the low thermal conductivity material are alternately arranged in the circumferential direction is laminated on the outer periphery of the layer ,
The fixing device according to claim 1 , wherein the high thermal conductivity material is an aluminum-based material, and the low thermal conductivity material is an iron-based material or a resin material . The fixing device according to claim 1 ,
The fixing device according to claim 1 , wherein the high thermal conductivity material is an aluminum-based material, and the low thermal conductivity material is an iron-based material or a resin material . The fixing device according to claim 1, 2, or 3,
Rotation position control means for controlling the rotation position of the heat transfer member is provided so that only the low thermal conductivity material region of the outer heat insulating layer contacts the pressure roller when rotation of the pressure roller is stopped. apparatus.   An image forming apparatus comprising the fixing device according to claim 1.

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