JPH06318000A - Image fixing device - Google Patents

Abstract

PURPOSE:To provide an image fixing device preventing the generation of an offset and making heat efficiency excellent. reducing the cost and having excellent durability. CONSTITUTION:The image fixing device is provided with a heating pipe 2 parallelly arranged along the axial direction of a pressure roller 1 and forming a heating body, a nipping part 3 press-contacting with the heat radiating part 2a of the heating pipe, a carrying means 7 carrying a heat resistant film 6 on which processing for releasing is executed, at the same speed as the carrying speed of a transfer paper 5 which is pressed to contact on the nipping part and on which an unfixed toner image 4 is held and moreover, a heating means fixedly disposed as another body by a different shaft from the heating pipe 2 and heating it and heats the surface having the unfixed toner image 4 of the transfer paper 5 with the nipping part 3 via the heat resistant film 6 and allowing the transfer paper 5 to pass, so that the unfixed toner image 4 on the transfer paper is fixed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image fixing apparatus using a heating member such as a heating roller used in an image forming apparatus such as a copying machine, a printer and a facsimile. The present invention relates to an improvement of an image fixing device that heats and fixes with a heating member composed of.

[0002]

2. Description of the Related Art In a conventional image fixing device using a heating roller or the like, a transfer paper holding an unfixed toner image to be fixed is nipped and conveyed in a nip portion between the heating roller and the pressure roller to transfer the transfer paper to the transfer paper. By applying heat and pressure,
An unfixed toner image or the like is fixed on the transfer paper. In such a fixing device, in order to prevent the so-called offset phenomenon in which the toner is transferred to the heating roller, the transfer paper on which the unfixed toner image to be fixed is held is passed through a thin linear heating element through a fixing film. It has been proposed that the unfixed toner image or the like is fixed to a transfer paper by being pressed against a pressure roller (Japanese Patent Laid-Open No. 1-263680). However, the heat generation range of the linear thin heat generating element as described above is limited to the range of the maximum paper passing width of the transfer paper used in the fixing device. FIG. 7 is a graph showing the state of a conventional image fixing device. In such a case, the temperature distribution in the axial direction of the roller is particularly continuous with a transfer paper having a size smaller than the maximum width of the transfer paper used. If the paper is passed for a long time, the non-paper-passing area will reach a high temperature, exceeding the control temperature, which may have an unfavorable adverse effect such as damage to the fixing film, or continuous transfer of small size transfer paper. If the transfer paper of a size larger than the small size is passed after the paper has been passed for a long time, there is a problem that an undesirable offset occurs due to the influence of the high temperature portion.

FIG. 8 is a side view of a main part of a conventional image fixing device. In order to eliminate the above-mentioned uneven temperature distribution, a rod-shaped heating means 108 is coaxially provided as a heating body. The use of pipe 102 has also been proposed. However, such a device is complicated and has a large number of parts, and it is difficult to attach and detach the heating means 108 and the heat pipe 102, which is expensive and costly. In order to eliminate any problems and strengths when using the above heat pipe, in the main body of the heating roll,
There has also been proposed a fixing heating roll for an electronic copying machine in which a positive temperature coefficient thermistor is sandwiched between two heat pipes to reduce cost (Japanese Patent Publication No. 61-32668). However, there is a problem of thermal efficiency through the heating roll body and safety due to energization of the rotating body.Even when such a heating roll is used, the occurrence of offset is prevented, and safety and thermal efficiency are good, It has not been possible to provide an image fixing device having excellent durability that can reduce costs.

[0004]

The conventional image fixing apparatus has problems such as occurrence of offset, safety problems, poor thermal efficiency, high cost and poor durability.

[0005]

SUMMARY OF THE INVENTION Therefore, the present invention is to solve such a problem. In other words, prevent the occurrence of offset,
It is an object of the present invention to provide an image fixing device having good thermal efficiency and excellent durability that can reduce costs.

[0006]

In order to achieve the above object, the present invention provides an undecided transfer paper by passing a transfer paper carrying an unfixed toner image between a heating body and a pressure roller. In an image fixing device configured to fix a deposited toner image, a heat pipe forming a heating element arranged in parallel along an axial direction on an outer peripheral surface of a pressure roller, and the above-mentioned heating member press-contacting with a heat radiating portion of the heat pipe. A nip portion formed between the pressure roller, a conveying unit that conveys the heat-resistant film that has been subjected to release processing at the same speed as the conveying speed of the transfer paper by being pressed against the nip portion, and the heat pipe. A heating means for heating the heat pipe, which is separately fixedly mounted on a separate shaft, and allows the unfixed toner surface on the transfer paper to pass through the heat resistant film while being heated in the nip portion. To To fix the unfixed toner on the transfer paper, to fix the heat pipe, to arrange the heating means outside the conveying means, and to arrange the heating means inside the conveying means. The heating means is configured to heat the heat pipe in a non-contact manner, and the heating means is configured to contact and heat the heat pipe.

[0007]

According to the image fixing device constructed as described above, the heat pipe is heated by the heating means separately fixed to the heat pipe by a separate shaft, and the heat pipe is heated to form an unfixed toner image surface on the transfer paper. Through the above heat-resistant film while heating under pressure at the nip portion to pass through to fix the unfixed toner image on the transfer paper, prevent the occurrence of offset, improve thermal efficiency, and reduce cost. An image fixing device having excellent properties can be provided.

[0008]

Embodiments of the present invention will now be described with reference to the drawings. 1 and 2 are a front view and a side view of a main part of an image fixing device according to an embodiment of the present invention. FIG. 1 and FIG. 2 show a pressure roller 1 which is pushed up from below by a spring (not shown) to apply upward pressure. An image forming apparatus (not shown) is provided at a nip portion 3 formed between a heat pipe 2 forming a heating element arranged in parallel along the axial direction and a pressure roller 1 in pressure contact with a heat radiating portion 2a of the heat pipe 2. The transfer paper 5 having the unfixed toner image 4 transferred by the transfer unit is guided by a guide plate (not shown) and conveyed in the direction of arrow A, where the heat-resistant film 6 is applied to the surface of the unfixed toner image 4. The unfixed toner image 4 on the transfer paper is fixed and conveyed in the direction of arrow B to be discharged by being pressed against the heat radiating portion 2a and passing through while being heated.

Unfixed toner image 4 on the heat resistant film 6
PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer), P
A release layer made of TFE (polytetrafluoroethylene), silicone resin, etc. is provided, and the heat pipe 2,
The drive roller 7a and the driven roller 7b are provided with a stopper mechanism (not shown) so as to be endless. The nip portion 3 is moved by the conveying means 7 including a driving roller 7a.
The heat-resisting film 6 subjected to the release treatment is conveyed at the same speed as the conveying speed of the transfer paper 5 which is pressed against and the unfixed toner image 4 is held.

The heating (evaporating) portion 2b of the heat pipe 2
_The heating means 8 for heating ₁ from the outside is arranged at a position separate from the heat pipe 2 and outside the heat-resistant film 6 which is endlessly configured on the conveying means 7 and is disposed in a main body device or the like separate from the heat pipe 2. It is fixed. The heating means 8 includes a temperature detecting element (not shown), and the temperature detecting element is in pressure contact with the heat pipe 2, and the heating (evaporating) portion 2b _{1 of the} heat pipe 2 is based on the temperature detection result of the temperature detecting element. Is designed to be heated,
Since the temperature distribution is made uniform, it is possible to provide an image fixing device that prevents the occurrence of offset, has good thermal efficiency, and is excellent in durability, which can reduce cost. The heat pipe 2 is not limited to the circular shape of the rotating body as described above, and as long as the above object can be achieved,
It may have another fixed shape.

The basic structure and function of the heat pipe 2 of the present invention can be understood by a generally known heat pipe. That is, the structure is such that a working fluid, which is a heat transport medium, is enclosed in a pipe container (container) in which a porous material called a wick having a capillary action (for example, wire mesh or sintered metal) is provided in the pipe. With this, a large amount of heat can be transported with a small temperature difference, the temperature distribution is small over the entire heat pipe, and the evaporation part and the condensation part can be arranged separately. In the present invention, in one example, copper is used as the material of the pipe container and water or the like is used as the working fluid.

FIGS. 3 and 4 are a front view and a side view of a main part of another embodiment of the present invention. A heater lamp 8a of a heating means 8 for heating the heating (evaporating) part 2b ₂ of the heat pipe 2 from above. The reflector 8b and the reflector 8b are arranged and fixed at a position separate from the heat pipe 2 inside the heat-resistant film 6 which is endlessly formed on the conveying means 7 and separately from the heat pipe 2. Ceramic coating is applied to the surface of the heater lamp 8a on the side of the reflector 8b. The inner surface of the reflector 8b is mirror-finished to improve the reflectance. The heating (evaporation) section 2b ₂ is different from the heating (evaporation) section 2b ₁ of the heat pipe 2 of Figure 2, since it is arranged inside the heat-resistant film 6 main device is miniaturized, small footprint Become. The description of the other structures is the same as the structure of the embodiment described with reference to FIGS.

FIG. 5 and FIG. 6 are a front view and a side view of a main part of another embodiment of the present invention. Heating means for heating the heating (evaporating) part 2b ₂ of the heat pipe 2 by contacting it from the outer upper part. The sheet heating element 8c of 8 is a heater obtained by baking an alumina ceramic substrate on which a heating resistor and glass are printed and laminated, and the contact portion is provided with a heat resistant and insulating layer. For example, polyimido coat, Teflon coat and the like. The planar heating element 8c may be another heating element such as a ceramic heater. Since the planar heating element 8c does not require the reflector 8b or the like, the assembly of the device is easy and the cost is reduced, and the direct heating method provides good thermal efficiency.
The description of the other structures is the same as that of the embodiment described with reference to FIGS.

[0014]

Since the present invention is configured as described above, the unfixed toner on the transfer paper is heated by heating the heat pipe by the heating means separately fixedly arranged on the heat pipe. The unfixed toner image on the transfer paper is fixed by heating and passing the image surface through the heat resistant film in the nip portion while pressing it, thus preventing the occurrence of offset, good thermal efficiency, and cost reduction. It has become possible to provide an image fixing device having excellent durability.

[Brief description of drawings]

FIG. 1 is a front view of a main part of an image fixing device showing an embodiment of the present invention.

FIG. 2 is a side view of FIG.

FIG. 3 is a front view of a main part of an image fixing device showing another embodiment of the present invention.

FIG. 4 is a side view of FIG.

FIG. 5 is a front view of a main part of an image fixing device showing another embodiment of the present invention.

FIG. 6 is a side view of FIG.

FIG. 7 is a graph illustrating a state of a conventional image fixing device.

FIG. 8 is a side view of a main part of another conventional image fixing device.

[Explanation of symbols]

1 ... Pressure roller, 2 ... Heat pipe, 2a ...
・ Heat dissipation part, 2b ₁ ... Heating (evaporation) part, 2b ₂ ...
Heating (evaporation) part, 3 ... Nip part, 4 ... Unfixed toner image, 5 ... Transfer paper, 6 ... Heat resistant film, 7
... conveying means, 7a ... driving roller, 7b ... driven roller, 8 ... heating means, 8a ... heater lamp, 8b ... reflecting plate, 8c ... planar heating element, 101
... Pressure roller, 102 ... Heat pipe, 102
a ... heat dissipation part, 102b ... heating (evaporation) part, 10
3 ... Nip portion, 104 ... Unfixed toner image, 10
5 ... Transfer paper, 108 ... Heating means.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Sotohiro Tsujihara 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Kenichi Hasegawa 1-3-6 Nakamagome, Ota-ku, Tokyo In stock company Ricoh (72) Inventor Masahiko Sato 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh stock company (72) Inventor Yasuhiro Kodaira 1-3-6 Nakamagome, Ota-ku Tokyo (72) Inventor Eiji Sawamura 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd.

Claims (6)

[Claims] 1. An image fixing device configured to fix an unfixed toner image on the transfer paper by passing a transfer paper carrying the unfixed toner image between a heating body and a pressure roller. A heat pipe that forms a heating element that is arranged parallel to the outer peripheral surface of the pressure roller along the axial direction; and a nip portion that is formed between the heat roller and the pressure roller that is in pressure contact with the heat dissipation portion of the heat pipe, Conveying means for conveying the heat-resistant film that has been press-contacted at the nip portion and subjected to release processing at the same speed as the conveying speed of the transfer paper; A heating means for heating the unfixed toner on the transfer paper while passing the unfixed toner surface on the transfer paper through the heat-resistant film while heating at the nip portion. An image fixing device characterized by the above. 2. The image fixing device according to claim 1, wherein the heat pipe is fixed. 3. The image fixing device according to claim 1, wherein the heating means is arranged outside the conveying means. 4. The image fixing device according to claim 1, wherein the heating means is arranged inside the conveying means. 5. The heating means is configured to heat the heat pipe in a non-contact state.
The image fixing device described. 6. The image fixing device according to claim 1, wherein the heating means is configured to contact a heat pipe to heat it.