JP2007127900A - Fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device capable of preventing the movement of heat to an atmosphere (vicinity of a fixing roller and a pressure roller) while assuming that a heat transfer member is arranged in contact with a part of the surface of the fixing roller. <P>SOLUTION: In the fixing device where the heat transfer member 11 of a long-shaft roller type is arranged to be brought into contact with the surface of the fixing roller 1 in parallel, the heat transfer member 11 is constituted by arranging a high heat conductivity material 13 and a low heat conductivity material 14 alternately in a periphery direction on the outer periphery of a heat insulating layer 12 made of resin. <P>COPYRIGHT: (C)2007,JPO&INPIT

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 the surface of the fixing roller formed of a material having releasability with respect to the toner, for example, silicone rubber or fluororesin, is pressed against the pressure roller, and the pressure contact portion of both rollers is formed. The unfixed toner image on the recording paper passing through the nip is fixed by heating and pressing.
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 images are continuously formed on recording paper of a small size compared to the fixing roller width (axial direction; length in the longitudinal direction), the heat at the end of the fixing roller is not absorbed by the recording paper, so the end of the fixing roller in the width direction The temperature of the portion becomes higher than the central portion of the fixing roller, and the temperature of the end portion of the pressure roller that is in direct contact with the portion becomes higher than that of the central portion 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 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 detecting member is arranged 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, and 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 fixing roller to make the temperature of the fixing roller uniform. In this configuration, it is desirable that the heat transfer member is brought into contact with the entire width of the fixing 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 fixing 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 and circumferential directions, so they move from the fixing roller to the heat transfer member and from there. The amount of heat that escapes (moves) into the atmosphere also increases. Therefore, the technique of arranging the heat transfer member in contact with a part of the surface of the conventional fixing roller to make the temperature of the fixing roller uniform improves the effect of making the temperature distribution in the longitudinal direction of the fixing roller uniform. However, as a whole, the temperature is lowered, resulting in a problem that the thermal efficiency is lowered.
The present invention has been made in order to solve the above-described conventional problems, and an object of the present invention is to provide an atmosphere (on the premise that a heat transfer member is placed in contact with a part of the surface of the fixing roller. It is an object of the present invention to provide a fixing device and an image forming apparatus capable of improving heat efficiency by preventing heat transfer to the vicinity of the fixing roller and the pressure roller.

In order to achieve the above object, the invention according to claim 1 is a fixing device in which a heat transfer member in the form of a long-axis roller is placed in parallel with the surface of the fixing roller, and the heat transfer member is a heat insulating member made of resin. The main feature is a fixing device configured by alternately arranging a high thermal conductivity material and a low thermal conductivity material in the circumferential direction on the outer periphery of the layer.
The invention according to claim 2 is characterized in that, in the fixing device according to claim 1, a fixing device in which a heat pipe is inserted in a high thermal conductivity material.
According to a third aspect of the present invention, in the fixing device of the first aspect, the main feature is a fixing device which is an aluminum-based material having a high thermal conductivity and the low thermal conductivity material is an iron-based material or a resin material.
According to a fourth aspect of the present invention, in the fixing device of the first aspect, the rotational position for controlling the rotational position of the heat transfer member so that only the low thermal conductivity material region of the heat transfer member contacts the fixing roller when the rotation of the fixing roller is stopped. A fixing device provided with a control means is a main feature.
According to a fifth aspect of the present invention, an image forming apparatus equipped with the fixing device according to the first aspect is the main 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 placed in parallel with the surface of the fixing roller, the heat transfer member is disposed on the outer periphery of the resin heat insulating layer with the high thermal conductivity material and the low heat. Since the conductivity material is alternately arranged in the circumferential direction, heat transfer to the atmosphere (in the vicinity of 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.
Further, when the fixing roller rotation is stopped, only the low thermal conductivity material region of the heat transfer member is brought into contact with the fixing roller, so that the heat transfer from the contact portion with the fixing roller to the heat transfer member during the fixing roller rotation stop. 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. FIG. 1 is a front view of the fixing device mounted on the image forming apparatus as viewed from the front side of the image forming apparatus. () Is a side view of the fixing roller portion of (1).
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 controls the temperature to be constant by a temperature control device (not shown). .
When the unfixed image 6 passes through the nip that is the pressure contact portion between the fixing roller 1 and the pressure roller 2, the toner is melted and the pressure is applied to fix the unfixed image 6 on the recording paper 5. The heat transfer member 11 contacts the fixing roller 1 in parallel, and the temperature distribution of the fixing roller 1 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 fixing roller 1, and the axial direction (longitudinal direction) of the fixing roller 1 is matched.
FIG. 2 is a block diagram showing a first embodiment of the heat transfer member shown in FIG. The heat transfer member 11 is configured by alternately arranging a high thermal conductivity material 13 and a low thermal conductivity material 14 on the outer periphery of a resin heat insulating layer 12.
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.

FIG. 3 is an enlarged configuration diagram of a main part showing a second embodiment of the heat transfer member 11 shown in FIG. In the second embodiment, a heat pipe 15 is inserted into a high thermal conductivity material (for example, aluminum-based material) 13.
4 is a view showing a detection mechanism of the low thermal conductivity material 13 shown in FIGS. 2 and 3, wherein (1) is a front view and (2) is a top view.
The position of the low thermal conductivity material 14 of the heat transfer member 11 is set so as to detect the filler 21 and the filler 21 provided on the rotating shaft of the heat transfer member 11 so as to rotate in synchronization with the heat transfer member 11. Detected by the photosensor 22. Then, the rotation of the fixing roller 1 is stopped at a position where the fixing roller 1 and the low thermal conductivity material 14 of the heat transfer member 11 contact each other. That is, when the rotation of the fixing roller 1 is stopped, the fixing roller 1 and the low thermal conductivity material 14 of the heat transfer member 11 come into contact with each other. Thereby, the movement of heat from the contact portion with the fixing roller to the heat transfer member can be reduced while the rotation of the fixing roller is stopped.
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 fixing roller 1 but also in a fixing device of a fixing belt type.

1 is a configuration diagram of a fixing device according to an embodiment of the present invention. It is a block diagram which shows the 1st Example of the heat transfer member shown in FIG. It is a principal part expanded block diagram which shows the 2nd Example of the heat transfer member shown in FIG. It is a 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 Heat insulation layer 13 High thermal conductivity material 14 Low thermal conductivity material 15 Heat pipe 21 Filler (component of rotational position control means)
22 Photosensor (component of rotational position control means)

Claims (5)

  In the fixing device in which a heat transfer member in the form of a long axis roller is placed in parallel contact with the surface of the fixing roller, the heat transfer member surrounds a high heat conductivity material and a low heat conductivity material on the outer periphery of a resin heat insulating layer. A fixing device characterized by being alternately arranged in a direction.   The fixing device according to claim 1, wherein a heat pipe is inserted into the high thermal conductivity material.   2. 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 rotation position control means is provided for controlling the rotation position of the heat transfer member so that only the low thermal conductivity material region of the heat transfer member contacts the fixing roller when the rotation of the fixing roller is stopped. Item 2. The fixing device according to Item 1.   An image forming apparatus equipped with the fixing device according to claim 1.

Images