JP2003272806A - Heating element and fixing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device of which, safety is secured, power consumption is reduced, and wait time is shortened. <P>SOLUTION: For the heating element made of sheet-shaped metallic material covered by layers, the heat conductivity of the layer, formed on one side of the heating element heating an object to be heated, is higher than that of the layer formed to the opposite side. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an unfixed image in an image forming apparatus having an image forming means for electrostatically forming a toner image on a transfer material such as a copying machine, a printer and a facsimile regardless of whether it is a single color or a color. And a heating device in which an insulating layer sandwiches a sheet-shaped metal heating element,
The present invention relates to a fixing device or an image forming apparatus having this heating body.

[0002]

2. Description of the Related Art In general, a heat roller type device has been widely used as a fixing device for thermally fixing a material to be heated.

This heating device of the heating roller system is provided with a heating roller heated by a built-in heating element such as a halogen heater to maintain a predetermined temperature, and a pressure contact nip portion of an elastic pressure roller pressed against the heating roller. The heating material is introduced and nipped and conveyed to heat-fix the material to be heated by the heat of the heating roller.

However, in this heat roller type apparatus, the temperature of the heat roller must be constantly maintained at a high temperature so that an image can be output immediately at any time. Even during standby, heat was released into the machine, causing a problem of temperature rise inside the machine. In addition, a considerable waiting time is required after the power is turned on until the heating roller reaches a predetermined temperature suitable for heating the material to be heated.

Therefore, in order to save energy and shorten the wait time, Japanese Patent Laid-Open No. 63-313128,
JP-A-2-157878, 4-44075-4408
As described in JP-A No. 3,4-204980-204984, a small fixedly-supported heating body, a film running while abutting on the heating body, and a pressurizing member to be pressed against the heating body via the film. It has been proposed that it is composed of a member and is configured to have a small heat capacity as a whole.

A film is brought into close contact with a heating member by a pressure member and slid and conveyed, and a material to be heated carrying an unfixed image is held in a pressure contact nip portion formed by the heating member and the pressure member with the film interposed therebetween. It is an apparatus that is introduced and conveyed together with a film, and fixes an unfixed image as a permanent image on a material to be heated by heat from a heating body applied through the film and pressing force of a pressure contact nip portion.

[0007] As a heating element, even a low heat capacity with a rapid temperature rise,
For example, it is possible to use a ceramic heater having an insulating / heat-conductive ceramic base material and a resistance heating layer which is provided on the surface of the base material and generates heat upon energization as a basic constituent body. Since the one with a low heat capacity can be used, the temperature of the heating element rises in a short time,
It is not necessary to supply power to the heating element during standby, and even if the heating material is passed through immediately, the heating material can be sufficiently heated to a predetermined temperature before the heating material reaches the fixing device. It has become possible to shorten the wait time and save power.

Conventionally, an elastic body has been used as the pressing member,
In the case of a device in which the pressure member is a drive roller that conveys a material to be heated or a film, the conveyance speed of the material to be heated or the film is determined by the peripheral speed of the drive roller, so the heat of the pressure member as the drive roller is determined. If the expansion coefficient is large, the peripheral speed is apt to change.For example, in the case of the image heating fixing device of the image forming apparatus, when the recording material is located between the image forming portion such as the image transfer portion and the image heating fixing device, The heating material is pulled by the fixing device, so that the formed image stretches or the image blurs.

In order to prevent them, at present, a drive mechanism and a control for changing the rotational speed of the pressure member according to the change of the peripheral speed of the pressure member are attached, which makes the device complicated and costly. There is also the problem of becoming. Further, the above-mentioned problems are the same when a belt is used instead of the film, and in addition to that, there arise problems of complexity of a belt driving mechanism and cost increase.

Therefore, a pressure contact nip portion having a predetermined width is formed between the heating member having a heating pattern formed on a flexible substrate and a rigid pressing member. As a result, since the peripheral speed does not change due to the change in the thermal expansion coefficient of the pressure member, an image problem that the formed image expands or the image blurs, a drive mechanism that changes the rotation speed of the pressure member, and the like. No control need be installed.

[0011]

However, in the above fixing device, the nip width is important because of the material and thickness of the pressing member. Therefore, by covering a heating element made of a sheet-shaped metal material such as nichrome wire with an insulating layer or a protective layer made of a material such as polyimide, the heating element becomes flexible, and due to elastic deformation of the heating element, a fixing member is formed. The width of the nip between the pressure member and the pressure member can be secured.

However, if the sheet-shaped heating element made of a metallic material is used as it is, there is a possibility that it may oxidize or cause electric leakage. Therefore, it is necessary to cover the periphery of the heating element made of a sheet-shaped metal material with an insulating layer or a protective layer made of a material such as polyimide.

However, if a heating element made of a sheet-shaped metal material is covered with an insulating layer or a protective layer having the same thermal conductivity, safety and thermal efficiency may be deteriorated. For example, when an insulating layer having a high thermal conductivity is used, the thermal efficiency is good, so that the surface of the heating body that heats the material to be heated is immediately warmed during continuous paper feeding, and power can be saved. However, the surface of the heating element on the side opposite to the side that heats the material to be heated may quickly become warm and may become hot, and the surroundings of the heating element may melt and safety may not be ensured. is there.

On the other hand, when an insulating layer having a poor thermal conductivity is used, the surface of the heating element opposite to the surface on which the material to be heated is heated does not become warm and does not reach a high temperature because the thermal efficiency is poor. Since the surface of the body on which the material to be heated is heated is not warmed, the thermal efficiency is deteriorated, and it is impossible to save power and shorten the wait time, which are the features of this fixing device.

[0015]

Therefore, the present invention is a heating element, a fixing device, and an image forming apparatus characterized by the following configurations.

As shown in FIG. 1, a sheet-shaped heating element made of a metal material is arranged on an insulating flexible resin substrate, and the insulating resin is placed on the heating element and the substrate. A heating element configured to arrange layers, wherein the thermal conductivity of the flexible resin layer is better than that of the flexible resin substrate.

In FIG. 2, a sheet-shaped heating element made of a metallic material is arranged on an insulating flexible resin substrate, and an insulating flexible resin layer is arranged on the heating element and the substrate. In the heating element configured to further arrange a protective layer, the thermal conductivity of the flexible resin layer and the protective layer is better than that of the flexible resin substrate. Heating body to be.

A fixing device having the above heating element as shown in FIG.

A sheet-shaped heating element made of a metallic material is arranged on the flexible resin substrate having insulation properties as described above, and an insulating flexible resin layer is arranged on the heating element and the substrate. In the heating element configured to have the above-mentioned flexible resin layer, the thermal conductivity of the flexible resin layer is better than that of the flexible resin substrate. There is no danger of the surface of the product becoming hot and safety is assured. Also,
It is possible to reduce power consumption and wait time, which are features of the configuration of the fixing device.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION (Embodiment 1) In this embodiment, a sheet-shaped heating element made of a metallic material is arranged on a flexible resin substrate having an insulating property, and the heating element is insulated from the heating element on the substrate. In a heating element configured to dispose a flexible resin layer having heat conductivity, the thermal conductivity of the flexible resin layer is better than that of the flexible resin substrate. It is a heating body.
FIG. 1 shows a schematic cross-sectional view of this heating body.

A heating element 3 is made of a sheet-shaped metal material. Further, regarding the shape, not only the sheet-shaped one but also the rod-shaped one and the linear one are included. Examples of the metal material include a single metal such as nichrome, tungsten, and aluminum, and alloys obtained by combining various metal materials.

Reference numeral 9 is a flexible resin layer having an insulating property.
Further, 8 is a flexible resin substrate having an insulating property. However, the layer 9 has a better thermal conductivity than the layer 8 by dispersing the carbon particles and the like. Further, it is possible to improve the thermal conductivity of the 8th layer as compared with the 9th layer by using materials having different thermal conductivities. As the flexible resin layer having insulation with the flexible resin substrate, not only insulation but also heat resistance, polyimide or polyamide imide,
Highly heat-resistant resins having insulating properties such as polyphenylene sulfide, polyether ether ketone, and liquid crystal polymers, and composite materials of these resins and ceramics, metals, glass, and the like are used.

As the protective layer 10, a layer in consideration of heat resistance and abrasion resistance is provided. As a result, even if the heating element and the fixing member rub against each other, they do not easily wear. However, since the thermal conductivity is deteriorated only by considering wear, the protective layers 10 and 9 are layers of the flexible resin layer having the insulating property, and the flexible resin substrate having the insulating property is used. It is desirable that the thermal conductivity is good in comparison.

The heating element having these structures is the heating element 3
When electricity is applied to the heating element, the heating element generates heat and is heated.

(Embodiment 2) FIG. 3 is a schematic cross-sectional view of a main portion of a fixing device having the heating element described in Embodiment 1 above.

A fixing member 1 is a film. The heating element 1a is the heating element described in the first embodiment. Two
Is a pressure roller as a pressure member. The pressure rollers 1 and 2 are arranged in parallel vertically and are pressed against each other with a predetermined pressing force.

Reference numeral N denotes a pressure contact nip portion (fixing nip portion) formed between the first and second portions by elastic deformation of the fixing member 1 by the pressure contact of the first and second portions. The pressure member 2 is rotationally driven in the clockwise direction by the driving means M, and the fixing member 1 is driven to rotate.

The fixing member 1 includes a film and a belt. The structure of the film will be described. First, the film is 3
Consists of layers, polyimide, polyetherketone,
Disperse a filler with high thermal conductivity such as metal boride powder in a heat resistant and insulating material such as polyether sulfone, polyether imide, and polyparabanic acid to a thickness of 50 μm.
A base layer formed on a cylindrical film having a thickness of about m, a release layer having a thickness of about 10 μm and made of a fluororesin or silicon resin such as PFA and PTFE on the outer surface thereof, and a primer layer having a thickness of about 5 μm for joining the two layers. Are formed from. Further, the belt is made of a heat resistant polyimide film or the like, and a release layer of PTFE (polytetrafluoroethylene) or the like is formed on the surface thereof.

The core material of the pressure roller 2 is for obtaining the strength of the pressure roller, and is made by processing aluminum or stainless steel into a cylindrical or hollow cylindrical shape, or a metal having high thermal conductivity such as aluminum or copper. Alternatively, a hollow cylindrical good heat conductive core material made of alumina or the like is used, and a fluororesin such as PFA or PTFE or a fluororubber / fluororesin mixed latex having a thickness of 10 to 50 μm is formed thereon as a heat-resistant release layer. Use the one coated with a thickness.

On the inner surface of the pressure roller 2, a low friction layer is provided at the contact portion of the temperature detecting means 4. However, in such an embodiment, the low friction layer is made of a material having good thermal conductivity or a thin thickness.

Then, the heating member 1 and the pressure member 2 are rotationally driven to energize the heating element 1a to generate heat, thereby heating the heating member 1a.
By raising the surface temperature of the sheet to a predetermined fixing temperature and introducing the heated material K on which the unfixed image is formed and carried to the pressure contact nip portion N, the heated material K moves to the pressure contact nip portion N. The unfixed developed image is nipped and conveyed, and is heat-pressure fixed on the surface of the material K to be heated by the heat of the heating member 1 and the pressure of the pressure contact nip portion N.

[0032]

EFFECTS OF THE INVENTION In a heating element having a layer formed so as to cover a sheet-shaped heating element made of a metallic material, the layer has a surface on the side opposite to that for heating the material to be heated. On the other hand, by using the heating element on which the layer having good thermal conductivity is formed, the surface on the opposite side does not have a high temperature and safety is secured. In addition, it is possible to save power and shorten the wait time, which are features of the fixing device.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a heating body including a flexible resin substrate and a flexible resin layer according to the present invention.

FIG. 2 is a cross-sectional view of a heating body including a flexible resin substrate, a protective layer, and a flexible resin layer according to the present invention.

FIG. 3 is an explanatory diagram showing an outline of a fixing device according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Fixing member 1a Heating body 2 Pressurizing member 3 Heating element 4 Temperature detecting means 5 for heated material passing portion 5 Temperature detecting means for non-heated material passing portion 8 Flexible resin substrate having insulation (high thermal conductivity ) 9 Flexible resin layer having insulating properties (low thermal conductivity) 10 Protective layer

Claims (3)

[Claims] 1. A sheet-shaped heating element made of a metallic material is arranged on an insulating flexible resin substrate, and an insulating flexible resin layer is arranged on the heating element and the substrate. A heating element configured such that the thermal conductivity of the flexible resin layer is better than that of the flexible resin substrate. 2. A sheet-shaped heating element made of a metal material is disposed on an insulating flexible resin substrate, and an insulating flexible resin layer is disposed on the heating element and the substrate. In the heating element configured to further arrange the protective layer thereon, the thermal conductivity of the layer including the flexible resin layer and the protective layer is better than that of the flexible resin substrate. A heated body that is characterized by things. 3. A heating treatment is performed by passing a material to be heated through a nip portion formed by pressure contact between a heating member and a pressing member, the heating member being driven to move, a film or a belt, and this film. A fixing device comprising the heating element according to claim 1 or 2, which is in contact with the surface of the belt opposite to the nip portion.