JPH08220908A - Inside face heat generation type heat roller - Google Patents

Abstract

PURPOSE: To shorten a rising time, to reduce a power consumption and to enhance image quality and the durability of a roller by providing a roller base material formed of a metallic pipe, an insulating material coated layer, a heating resistor layer and a rotatably supported electrode. CONSTITUTION: An insulating layer 12 is formed on the inner peripheral surface of the roller base material 11 formed of the metallic pipe, and the heating resistor layer 14 is formed on the layer 12. And also, a heat-resistant high releasability type resin layer 13 is formed on the outer peripheral surface of the roller base material 11. Besides, a conductive metallic ring electrode 15 is rotatably attached to both end parts of the roller base material 11. And when a voltage is impressed on the electrode 15 at both ends from a supporting roller through an electrical contact, a current flows through the heating resistor layer 14, then, the heat is generated, and the heat roller 10 is heated. In this case, the heat is radiated from both end parts of the heat roller 10, but, the generated heat quantity is more increased as it comes closer to both end parts since the spiral distance of a pattern is formed more densely as it comes closer to both end parts, consequently, the uniform temperature distribution can be obtained over the entire length of the heat roller 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal heat roller constituting a heat roller fixing device in an electrophotographic printer or a copying machine.

[0002]

2. Description of the Related Art Conventionally, in electrophotographic printers and copying machines, a charged photosensitive drum is irradiated by a light source to form an electrostatic latent image on the drum surface, and toner is attached to the electrostatic latent image. After development, the toner image is transferred to a transfer paper, and then the transfer paper is sent to a heat roller fixing device and heated and pressed between a heat roller and a pressure roller to melt the toner image. The image is fixed by pressing it on the paper.

FIG. 4 shows an example of a commonly used heat roller. In this heat roller, a heater 2 composed of a halogen lamp or the like is built in a roller base material 1 made of a metal tube having a high thermal conductivity such as aluminum, and the heat generated by the heater 2 causes the roller base material 1 to be heated. Is heated to about 150 to 200 ° C. A heat-resistant and high-release resin layer 3 is formed on the outer peripheral surface of the roller base material 1 to prevent a phenomenon (offset phenomenon) in which a part of the toner is transferred to the outer peripheral surface of the heat roller.

However, in the case of the heat roller as shown in FIG. 4, it takes about 3 to 5 minutes for the surface temperature of the roller base material 1 to reach a usable temperature of 150 to 200 ° C. after the heater is turned on. There is a problem that it takes time and power consumption of 0.5 to 1.5 kW is required.

Therefore, in recent years, the rise time is short,
Moreover, heat rollers with low power consumption have been proposed.

For example, Japanese Patent Application No. 62-141596 discloses a heat roller having a structure as shown in FIG. That is, in this heat roller, the heat generating resistor layer 5 is formed on the outer peripheral surface of the roller base material 4 made of a low heat conductor such as glass, enamel, or ceramics, and the heat resistant and high release resin layer 6 is formed further outside thereof. ing. Then, ring-shaped electrodes (not shown) are attached to both ends of the heating resistor layer 5 so that a voltage is applied between both electrodes. In the case of the heat roller having such a configuration, the rising time is about 1 minute, and the power consumption can be reduced.

[0007]

However, in the heat roller having the above structure, since the heat-resistant and high-release resin layer is formed on the surface of the heating resistor layer, the heat-resistant and high-release resin coating property is high. It tends to be insufficient, and the flatness, straightness, wall thickness, etc. of the roller become uneven, and it is difficult to keep these within the allowable range, and there is the problem that weld lines occur and weak parts occur. . As a result, the image quality of the resulting copy is deteriorated and the durability of the roller is impaired.

In view of the above problems of the conventional heat roller, it is an object of the present invention to provide a metal heat roller having a short start-up time, low power consumption, and excellent image quality and roller durability. To do.

[0009]

In order to achieve the above object, a metal heat roller of the present invention comprises a roller base material made of a metal tube and an insulating film formed on the inner peripheral surface of the roller base material. A layer, a heating resistor layer formed on the insulating layer, and electrodes rotatably supported on both ends of the roller base material so as to be electrically connected to the heating resistor layer. It is characterized by

A heat resistant and high release resin layer is preferably formed on the outer peripheral surface of the roller base material of the present invention.

While the conventional heat roller uses indirect heating with a halogen lamp or the like, the heat roller according to the present invention has a heating resistor on the inner peripheral surface of the roller, and therefore the roller itself. It can be heated directly, the temperature rising speed of the roller is high, and the temperature can be raised to the required temperature in a short time, and at the same time, the power consumption required at this time can be reduced.

The present invention is different from the invention described in Japanese Patent Application No. 62-141596 in that the heat-generating resistor is formed on the inner surface of the metal tube. Therefore, the heat-resistant high-release mold is directly formed on the outer surface of the roller made of the metal tube. A resin layer can be formed. Therefore, there is no difference between the normal heat roll and its outer surface, and the flatness, straightness, wall thickness, etc. of the roller can be maintained at the same level as the conventional roller, maintaining high quality image quality,
The durability of the roller can also be maintained.

The heat-generating resistor layer is formed by spirally patterning the heat-generating resistor along the inner peripheral surface of the roller base material, or the amount of heat generated from the central portion of the roller base material toward both ends thereof. It is preferably patterned to increase. By arranging the heating resistors in this way, heating by the roller can be performed uniformly, while maintaining a high quality image, shortening the startup time,
It also works effectively for efficient use of electric power.

The insulating layer serves to prevent electricity from being applied to the metal tube. The insulating layer is ceramics,
It is made of an insulator such as enamel, alumite, a resin coating or a heat resistant silicone coating. The ceramics layer can be formed by, for example, thermal spraying of ceramic powder or coating the ceramic powder with a binder and then firing. The alumite layer is obtained, for example, by electrolytically oxidizing an aluminum tube. Also,
A heat roller may be obtained by electrolytically oxidizing the entire aluminum tube into alumite. Among the alumites, hard alumite is preferable. The enamel layer is obtained, for example, by lining a low melting point glass on the inner peripheral surface of a metal tube. At this time, if the difference in thermal expansion between the lining layer and the metal is large, the lining layer is likely to be damaged after the lining. Therefore, it is necessary to select a combination having a small difference in thermal expansion coefficient. The resin layer is obtained, for example, by sticking a heat-resistant resin film to the inner peripheral surface of the metal pipe. Further, the heat-resistant silicone coating is formed by adding polysiloxane to metal oxides (aluminum oxide, silicon oxide,
It is obtained by applying a mixture of titanium oxide, calcium oxide, etc.).

[0015]

In the metal heat roller of the present invention, an insulating layer is provided on the inner peripheral surface of a roller base material made of a metal tube, and a heating resistor layer is further formed on the insulating layer. Since the roller is heated by supplying current to the heating resistor layer to generate heat, the start-up time to reach a predetermined temperature is shorter than that of the conventional halogen lamp type heat roller shown in FIG. Electric power can also be reduced. At the same time, there is an advantage that a halogen lamp or the like is unnecessary and the number of component parts of the equipment can be reduced.

If the start-up time of the heat roller until reaching a predetermined temperature is short, work such as copying can be performed without causing so-called waiting time. Since there was this waiting time in the past, it was necessary to wait for several minutes after turning on the power before using it, and even after the temperature once rose,
It is obliged to leave the halogen lamp on or off to maintain the temperature or preheat it by some other means to maintain a constant temperature. Therefore, the fact that the time for raising the temperature to the predetermined temperature is short has an important meaning for the actual work such as copying.

In a conventional copying machine or the like, it takes a considerable amount of time to raise the temperature to the required temperature, and in order to quickly start the copying work, it is necessary to take measures such as preheating even after the temperature rises. And doing pretty wasteful things.
On the other hand, in the present invention, since the temperature rising time is short, even if the power source of the copying machine or the like is turned on for each copying operation, the characteristic can be immediately put into the copying operation. This advantage is great.

In the present invention, since the heating resistor is formed on the inner surface of the metal tube, the heat resistant and high release resin layer can be directly formed on the outer surface of the roller made of the metal tube. The outer surface is no different,
The flatness, straightness, wall thickness, etc. of the roller can be maintained at the same level as the conventional roller, high quality image quality can be maintained, and the durability of the roller can be maintained.

Further, the pattern and the thickness of the heating resistor layer can be freely set. In a preferred embodiment of the present invention, the heating resistor layer is formed by spirally patterning the heating resistor along the inner peripheral surface of the roller base material, thereby facilitating the formation of the pattern and at the center of the roller base material. It becomes easy to adjust the amount of heat generated from the part to both ends. The heating resistor layer is patterned so that the amount of heat generated increases from the central portion of the roller base material toward both end portions, so that a uniform temperature distribution is obtained over the entire length of the roller and uneven fixing of toner is prevented. can do.

Furthermore, the heat-resistant and high-release resin can be directly coated on the outer peripheral surface of the roller base material, the adhesiveness of the resin is improved, and the durability is improved.

[0021]

【Example】

Example 1 FIG. 1 shows an example of the metal heat roller of the present invention. Note that FIG. 1 is a sectional view of the roller in the length direction.

In this heat roller 10, 11 is a roller base material made of a metal tube. This roller base material 11
Is made of aluminum having an outer diameter of 30 mmφ and a length of 300 mm.

Zirconia powder is plasma sprayed on the inner peripheral surface of the roller base material 11 to form an insulating layer 12 having a film thickness of 50 to 100 μm.
Was formed. For plasma spraying, a small torch that fits inside a tube with an inner diameter of 28 mmφ was specially manufactured and used.

A heating resistor layer 14 is formed on the insulating layer 12.
Are formed. The heating resistor layer 14 is formed by spirally patterning along the inner peripheral surface of the roller base material 11. In consideration of heat dissipation at both ends of the heat roller 10, this pattern has a spiral interval gradually increasing from the central portion of the heat roller 10 toward both ends so that the heat generation amount gradually increases toward the both ends of the roller. It is better to make it shorter.

The heating resistor layer 14 is a conductive paste containing a metal powder and a glass powder, here an Ag paste, is discharged from a nozzle in a fixed amount, and the inner periphery of the roller base material 11 (on the insulating layer 12) is discharged. It was applied by applying a predetermined spiral pattern on the surface and then baked in a heating furnace, and the resistance value was 20Ω. As the conductive paste, in addition to Ag paste, Ag-Pd, A
A paste containing g-Pt, Au, Cu or the like can be used. In addition to the above method, the heating resistor layer 14 can also be formed by, for example, a method of printing a transfer paper on which a predetermined conductive pattern is formed on the inner peripheral surface of the roller base material 11. The resistance value of the heating resistor layer 14 is preferably 10 to 30Ω.

A heat-resistant and high-release resin layer 13 for preventing an offset phenomenon is formed on the outer peripheral surface of the roller base material 11. As the heat-resistant and high-release resin layer 13, a fluororesin such as PFA (perfluoroalkoxy resin) or PTFE (polytetrafluoroethylene) is preferably used. The heat-resistant and high-release resin layer 13 preferably has a thickness of about 10 to 40 μm. When the thickness of the heat-resistant and high-release resin layer 13 is less than 10 μm, the durability becomes poor, and when it exceeds 40 μm, the heat transfer resistance increases and the surface smoothness may be impaired.

At both ends of the roller base material 11, ring-shaped electrodes 15 made of a conductive metal (brass, stainless steel, etc.) are used.
Is installed. As shown in FIG. 1, the electrodes 15 are connected by conductors 16 to both ends of the pattern of the heating resistor layer 14.

As shown in FIG. 2, the heat roller 10 is rotatably supported by the three support rollers 17 at the electrodes 15 at both ends. One of the support rollers 17a is made of a conductive material and is connected to a power source (not shown). And this support roller 17
A voltage is applied to the electrode 15 from a through the electrical contact 18.

Next, the operation of the heat roller 10 will be described. When a voltage is applied from the support roller 17a to the electrodes 15 at both ends via the electrical contacts 18, a current flows through the heating resistor layer 14 in FIG. 3 to generate heat, and the heat roller 10 is heated. Although heat is dissipated at both ends of the heat roller 10, since the spiral intervals of the pattern are formed more densely toward both ends, the amount of heat generated increases toward both ends, and as a result, the heat roller 10 extends over its entire length. A uniform temperature distribution can be obtained. When the heat roller was actually heated, the startup time to reach a fixing temperature was about 10 seconds and the power consumption was about 700W. In the case of a roller that uses a conventional halogen lamp, the time required to raise it is 2
The power required was 900 W in minutes. The start-up time is greatly shortened, and work such as copying can be performed with almost no waiting time, which is highly practical.

Example 2 An aluminum tube having an outer diameter of 30 mmφ and a length of 300 mm, which has been hard anodized by electrolytic oxidation, is used.
Ag conductive paste containing metal powder (here silver) and glass powder is quantitatively discharged from a nozzle onto the inner peripheral surface of the alumite-treated tube so that a predetermined spiral pattern is formed on the inner surface of the tube. And finally heated in a heating furnace to form a heating resistor layer. The resistance value was 20Ω. Then, on the outer peripheral surface of the roller base material, a heat-resistant and high-release resin layer of PTFE for preventing the offset phenomenon was provided.

Further, metal ring-shaped electrodes were attached to both ends of the roller base material. The electrodes 15 are connected to both ends of the heating resistor layer by conductors.

2 and 3, when a voltage is applied from the supporting roller 17a to the electrodes 15 at both ends through the electrical contacts 18 in the same manner as in Example 1, a current flows through the heating resistor layer 14 to generate heat. The heat roller 10 is heated. The start-up time to reach the fixing temperature is about 12 seconds,
The power consumption was about 800W. In the case of a roller using a conventional halogen lamp, the time required for starting the roller was 2 minutes and the required power was 900W. Thus, it can be seen that the time required to raise the temperature is greatly reduced.

Example 3 On a polyimide film having a thickness of 30 mμ, a heating resistor (conductive paste) made of Ag was coated with a binder so as to form a spiral shape, and a polyimide film was further covered thereon, and then at about 200 ° C. Heated. Heat generating resistor made of polyimide sandwich, outer diameter 30mmφ, length 300
It was affixed to the inner peripheral surface of an aluminum tube of mm.

2 and 3, when a voltage is applied from the supporting roller 17a to the electrodes 15 at both ends through the electrical contacts 18 in the same manner as in Example 1, a current flows through the heating resistor layer 14 to generate heat. The heat roller 10 is heated. The startup time to reach the fixing temperature is about 11 seconds,
The roller rose to a predetermined temperature in a short time.

Example 4 40 parts of silicon oxide, 4.5 parts of aluminum oxide, 12 parts of sodium oxide, 0.5 part of potassium oxide as an insulating layer were formed on the inner peripheral surface of an aluminum tube having an outer diameter of 30 mmφ and a length of 300 mm. , 30 parts of boron oxide and 5 parts of zinc oxide were subjected to a holo-treatment with a chemical as a main component, and on this insulator layer,
A heating resistor was provided in the same manner as in Example 1.

2 and 3, when a voltage is applied from the supporting roller 17a to the electrodes 15 at both ends through the electrical contacts 18, a current flows through the heating resistor layer 14 to generate heat as in the first embodiment. The heat roller 10 is heated. The start-up time to reach the fixing temperature was about 12 seconds.

Example 5 An aluminum tube having an outer diameter of 30 mmφ and a length of 300 mm was spray-coated with compressed air on the inner peripheral surface of a mixture of water glass and a chemical agent containing silica and alumina as main components, followed by firing. It was A heating resistor was provided on this insulator layer in the same manner as in Example 1.

When the roller was heated from the supporting roller via the electrical contact in the same manner as in Example 1, the start-up time to reach the fixing temperature was about 12 seconds.

Example 6 71.5 parts of polysiloxane, 20 parts of aluminum oxide, 7.5 parts of silicon oxide, 6.5 parts of xylene and a catalyst were provided on the inner peripheral surface of an aluminum tube having an outer diameter of 30 mmφ and a length of 300 mm. A small mixture was coated and then heat treated. A heating resistor was provided on this insulator layer in the same manner as in Example 1.

When the roller was heated from the supporting roller via the electrical contact in the same manner as in Example 1, the temperature rose to the required temperature in a short time of about 11 seconds.

[0041]

EFFECTS OF THE INVENTION The metal heat roller of the present invention has a shorter start-up time until reaching a predetermined temperature, as compared with a conventional heat roller in which a light source is arranged in a drum for heating.
It consumes less power. Further, since the heating resistor is formed on the inner peripheral surface of the tube, the flatness of the outer peripheral surface of the roller base material,
High quality image with straightness and uniform thickness can be obtained. Then, the pattern and thickness of the heating resistor layer can be freely set. Further, the heat-resistant and high-release resin that coats the outer peripheral surface of the roller base material has good adhesiveness and high durability.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an embodiment of a metal heat roller of the present invention.

FIG. 2 A- of an embodiment of a metal heat roller of the present invention
It is a cross-sectional view taken along the line A ′.

FIG. 3 B- of an embodiment of a metal heat roller of the present invention
It is a cross-sectional view cut along line B '.

FIG. 4 is a cross-sectional view of an example of a conventional heat roller.

FIG. 5 is a cross-sectional view of another example of a conventional heat roller.

[Explanation of symbols]

 1, 4, 11 Roller equipment 2 Halogen lamp 3, 6, 13 Heat-resistant and high-release resin layer 5, 14 Heating resistor 10 Metal heat roller 12 Insulating layer 15 Electrode 16 Conductor 17 Support roller 17a Conductive support roller 18 Electrical contact

Claims (6)

[Claims] 1. A roller base material made of a metal tube, an insulating coating layer formed on an inner peripheral surface of the roller base material, and a heating resistor layer formed on the insulating coating layer. A metal heat roller, comprising: an electrode rotatably supported by being attached to both ends of the roller base material so as to be electrically connected to the heating resistor layer. 2. The metal heat roller according to claim 1, wherein the insulating layer formed on the inner peripheral surface of the roller material is a resin film. 3. The metal heat roller according to claim 1, wherein the insulating layer formed on the inner peripheral surface of the roller material is made of alumite. 4. The metal heat roller according to claim 1, wherein the insulating layer formed on the inner peripheral surface of the roller material is made of enamel. 5. The metal heat roller according to claim 1, wherein the insulating layer formed on the inner peripheral surface of the roller material is made of ceramic. 6. The metal heat roller according to claim 1, wherein the insulating layer formed on the inner peripheral surface of the roller material comprises a heat resistant silicone coating.