JPH01164982A - Welding roller - Google Patents

Abstract

PURPOSE: To prevent the occurrence of sepn. of layers in spite of high-temp. heating by adjoining a core and a resistance heating layer to each other and forming the core of a thermally and electrically insulative material and the resistance heating layer of a conductive material. CONSTITUTION: The roller 10 has the core 16, the resistance heating layer 14 connectable to a power source and an external protective layer 12. The core 16 is formed of the thermally and electrically insulative material and the resistance heating layer 14 of the conductive material. The resistance heating layer 14 is directly formed on the core 16. Since the core 16 and the resistance heating layer 14 are directly mounted, the number of the boundary surfaces between the layers decreases. As a result, the occurrence of peeling between the layers is prevented in spite of the high-temp. heating by selecting the material of these layers.

Description

TECHNICAL FIELD The present invention relates to electrophotography, and more particularly to a welding roller for heated roller welding.

TECHNICAL BACKGROUND U.S. Pat. No. 4,395,109 discloses a roller welding mechanism for welding toner to paper, etc., in which a thin heating layer is placed in close proximity to the surface of a heated roller. Positioned. This structure allows heat to be transferred quickly and efficiently to the surface of the roller. Therefore, the surface temperature of the roller can be precisely controlled and requires less power for heating.

This conventional roller has a core made of metal, ceramic or other material, on which an electrically insulating layer is provided. The electrically insulating layer acts as a support layer for the resistive heating layer. After the resistive heating layer is attached to the electrically insulating layer, the outer protective layer is attached. This layer provides a welding surface.

Connection between the resistive heating layer and the power source is made by conductive rings and electric bushings at each end of the roller. Heating of the rollers is accomplished by continuously passing an electric current through them.

Although this structure provides rapid and efficient heat transfer to the welding surface of the roller, its complex design requires many interfaces between layers. If the outer protective layer is one that requires a high temperature heat curing treatment, such as a fluorinated hydrocarbon, the high temperatures required for that treatment may cause separation at one of the layer interfaces and thus damage to the fuser roller. will occur.

A second problem with this structure is that the external electrical contact structure can become corroded by toner release oil, and such release oil can also penetrate internally and damage the roller. In other words, it is possible to give

OBJECTS OF THE INVENTION The present invention provides a fusing roller for use in electrophotographic devices, which has a core, a resistive heating layer, and an outer protective layer, the fusing roller having a core, a resistive heating layer, and an outer protective layer. The purpose is to provide the following.

Another object of the present invention is to provide a welding roller of the type described above, which is less likely to be damaged by peeling oil or the like and has means for connecting to a power source.

In other words, the fusing roller according to the present invention is an electrophotographic fusing roller having a core, a resistive heating layer connectable to a power source, and an outer protective layer, the core being thermally and electrically connected. The core is characterized in that the resistance heating layer is formed of an electrically conductive material, and that the resistance heating layer is provided directly on the core.

Preferably, the core material has a similar coefficient of thermal expansion to the material of the resistive heating layer, with glass being a preferred material.

In a preferred embodiment, the resistive heating layer is a thin, e.g. It is said to be the core of barium glass.

The outer protective layer is made of well-known durable materials,
For example, it may be one of silicone rubber or fluorinated hydrocarbons. The invention works best when the material used as the protective layer requires high temperature curing.

Further, the roller according to the present invention for achieving the above second object includes an inner core having an insulating outer surface, an outer protective layer supported on the outside of the insulating outer surface, the outer protective layer and A welding roller having a resistive heating layer formed between an inner core and conductive means for connecting the resistive heating layer to a power source, the conductive means adjacent an end of the core. an electrically conductive annular element provided with a cylindrical surface substantially continuous with the insulating outer surface, the cylindrical surface being in contact with the inner surface of the resistance heating layer; and means for electrically connecting the conductive annular element to a power source.

Functions and Effects of the Invention The present invention is constructed as described above, and
In the second invention, the core and the resistance heating layer are directly attached, and therefore there are fewer interfaces between the layers than in the prior art. Even if the roller is heated to a high temperature,
It is possible to prevent separation between these layers.

Furthermore, in the roller according to the second invention, since the conductive element of the conductive means is set inside the resistance heating layer, the conductive means is protected from release oil etc. applied to the outer surface of the heating layer. I can do it.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a welding roller 10 is part of a well-known welding mechanism. The fusing mechanism includes a pressure roller to form a heated nip and a mechanism 60 to supply release oil to prevent toner offset on the fusing roller.

As shown in FIG. 2, the welding roller IO has a core 16 and
It has a resistance heating layer 14 and a protective layer 12 that acts as a welding surface. A resistive heating layer is between the core and the protective layer. In order to limit electrical shorts and heat losses in the core 16 of the roller, the core 16 is thermally and electrically insulated, for example, the core is made of glass.

Resistive heating layer 14 is connected to a power source 28 via an electrical connection structure. The structure is such that current can be uniformly supplied to the resistance heating layer 14. The electrical contact structure includes conductive annular elements such as rings 18A, 18B which provide a large contact surface with the heating layer 14. The conductive annular element is adjacent to the core 16 and has a portion 19A119 having an outer diameter corresponding to the outer diameter of the insulating surface of the core 16.
and annular extensions 21A, 21B having outer diameters corresponding to the inner diameter of the core.

Conductive cylindrical elements such as plugs 22A, 22B are set at the axis of the welding roller 10, e.g.
It is connected to conductive rings 20A, 20B by 0A, 20B. Screw 20A.

The head of 20B is covered with a protective material 38 to avoid oil damage and provide insulation.

For example, the insulating annular elements 24A, 24B, such as rings made of phenolic material, are connected to the conductive plugs 22A, 2
2b, roller ends and conductive rings 18A, 1
Protects 8B from heat loss and released oil damage. The insulating rings 24A, 24B have portions 25A, 25B having the same outer diameter as the fusing roller 10, and the conductive rings 18A, 18B.
an annular extension 2 having an outer diameter equal to the inner diameter of
It has 6A and 26B.

The current required to heat the resistive heating layer 14 is supplied by the power source 2.
Powered by 8. Power supply 28 and conductive plug 22A,
Electrical contact with 22B is made by a well-known axial connection mechanism. In the preferred embodiment shown in FIG.
, 36B, and are pressed so as to be able to slide and rotate relative to each other within hemispherical recesses 32A, 32B provided at the ends of the conductive plugs 22A, 22.

In operation, electrical current is supplied from power supply 28 to spherical conductors 30A, 30B and plug 22A.

22B1 screws 20A, 20B, conductive ring 18A, 1
8B1 and flows through the resistive heating layer 14. When a current flows, the heating layer 14 heats the fusing roller 10, the insulating core 16 and the insulating ring 24A.

24B minimizes heat loss within the system.

The internal electrical contact structure shown in FIGS. 1 and 2 is almost entirely insulated and protected from stripping oil and the operating environment. Therefore, element corrosion, electrical contact deterioration,
And damage to the fusing roller due to release oil is reduced.

Since most of the contact structure is housed within the fusing roller, mechanical and electrical malfunctions are reduced. Axially positioned electrical conductors 30A, 30B connecting power to conductive end plugs 22A, 22B are located at each end of the fuser roller and are therefore less exposed to released oil, improving maintained electrical contact. Furthermore,
The required operating space is reduced.

The electrical continuity of resistive heating layer 14 maintains uniform heat applied to the welding surface. If the resistive heating layer were to become separated from the core during manufacture or use, damage to the resistive heating layer, such as cracking, would occur. Fuser roller materials with different coefficients of thermal expansion undergo varying amounts of expansion during manufacture or use, thus increasing the likelihood of resistive heating layer and core separation. For example, the outer protective layer 12
The curing process performed in this process requires high temperatures, which can cause such separation. Therefore, the materials used for the resistive heating layer and core should have good adhesive properties and similar coefficients of thermal expansion.

Many metal or alloy resistance materials that have particularly useful resistance properties in this type of fuser roller when used as a thin layer include 30xlO-' to N0 per 'C'.
It has a coefficient of thermal expansion of xIO-'length/length. Most glass components fall within this range. Therefore, glass is an excellent material to use as the core. In this regard, one or more glasses are compatible with each resistive material.

In the preferred embodiment shown, for example, polytetra 7
It has an adhesive outer protective layer 12 that requires a high curing temperature, such as ethylene fluoride, and a 0, 1 to 0.3 micron resistive heating layer made from an alloy of approximately 29% nickel and 71% iron. are doing. Due to the closeness in thermal expansion properties,
This alloy maintains excellent adhesion with cores made from alkali barium borosilicate glasses. However, other useful materials also adhere well to the same or other glasses.

For example, tungsten resistance heating layers are well matched with borosilicate, borosilicate soda, or borosilicate soda lime glass cores. Titanium resistance layers are suitable for potash soda lime or alkali barium glass cores, tantalum resistance heating layers are suitable for borosilicate lead, soda siliconia,
or used with a borosilicate soda glass core. Resistive heating layers made from certain carbon steels are suitable for glass cores made from potassium soda lime or potassium lead. Stainless steels containing 17% and 28% chromium are suitable for glass cores made from potassium lead, alkaline barium, or soda potassium lead. The alloy containing approximately 42% nickel, 6% chromium, and 52% iron is applied to a glass core made from potassium soda lead, soda lime, potassium lead, lead zinc borosilicate, alkali barium, alkali lead, or barium fluoride. . For resistive heating layers made of molybdenum, cores made of barium fluoride, alkali borosilicate, soda borosilicate, borosilicate, aluminosilicate, alkaline earth metal aluminosilicate are also preferred adhesive and heat Shows expansion properties. These cores also
1) Approximately 29% nickel, 71% iron, 2) 40.5-41.75% nickel cobalt, 59.
It also exhibits good adhesion to metal alloys of 5-58.25% iron, 3) 17% cobalt, and 83% iron.

The thickness of the resistive heating layer 14 is determined by the composition of the materials used and the power source. For example, when the resistive heating layer is made of the preferred nickel-iron alloy, it may be 0.1-0.3 microns thick.

The protective layer 12 is made of a material well known in the art, such as silicone rubber or polytetra-7tethylene, which at least allows the toner to easily separate from the protective layer 12 . For example, a protective layer of polytetrafluoroethylene having a thickness in the range of 1.0-2.0 mils, including any main layer, of a preferred nickel-iron alloy pre-coated onto a barium borosilicate glass core. Good results can be obtained when coated directly onto the resistive heating layer.

To manufacture the welding roller described above, the annular lengths 21A, 21B of the conductive rings 18a, 18b are completely inserted into each end of the core 16. Ring 18A.

The outer surfaces of portions 19A and 19B of 18B form a continuous surface of the outer surface of core 16. The method of connecting these parts depends on the type of material used. For example, if the glass core and the nickel-iron alloy conductive rings have similar thermal properties, permanent contact between the core 16 and the rings 18A, 18B may be made by welding or the like.

Resistive heating layer 14 is then formed as a coating over the continuous surface formed by core 16 and conductive rings 18A, 18B attached thereto. For example, the high-precision resistive heating layer described above can be formed by magnetron sputtering, which is well known in the art. The magnetron is specifically designed to evenly distribute the coating material around the substrate. The distribution conditions, i.e.
The emitted power source, vacuum pressure, substrate bias level, and temperature are controlled to form a resistive film with a specific coefficient of thermal expansion, temperature coefficient of resistance, and substrate adhesion.

Once the desired resistive heating layer thickness has been formed, the outer surface of resistive heating layer 14 is cleaned, such as by chemical etching. The bond strength between resistive heating layer 14 and protective layer 12 is strengthened by this cleaning. A protective layer 12 is then formed on all exposed surfaces of the resistive heating layer 14. For example, when forming a polyteorafluoroethylene protective layer, the main layer is applied to a thickness of 0.3-0.4 mils, approximately 23.
Heat at °C for 15 minutes. A layer of polyteola 7-fluorinated ethylene (PTFE) is then applied to a thickness of 0.5-1 S mils and cured for 30 minutes at about 385°C. The roller can be cured at this temperature without separation between the resistive layer according to the invention and the glass substrate.

Then the annular extension 26 of the insulating rings 24A, 24B
A, 26B is fully inserted into the center of conductive rings 18A, 18'B. A continuous surface of the fuser roller is maintained by the outer surface of portions 25A, 25B of insulating rings 24A, 24B. Part 25B of ring 24B is ring 24A
It has a larger axial length than the portion 25A, and is provided with means for driving the welding roller, such as a slot 34, to which a drive gear or the like can be attached.

The conductive plugs 22A, 22B are then connected to the insulating ring 2.
4A, 24B, and extends into portions 26A, 26B to additionally support the welding roller IO.

Electrical contact between the plugs 22A, 22B and the rings 18A, 18B is made by inserting conductive means, such as screws 20A, 20B, from the outer surface of the roller toward the axis of the co'yts. The screws are threaded into contact with resistive heating layer 14, conductive rings 18A, 18B, and insulating rings 22A, 22B. The head of the screw is protected from the environment by a coating such as silicone rubber.

After a drive device, such as a drive gear, is connected to the insulating ring 24B by the slot 34, the completed fusing roller 10 is installed into the xerographic apparatus by conventional means and the spherical conductors 30A, 30B are connected to the plugs 22A, 22B. It is connected to the power supply by fitting into the hemispherical part at the end of the

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments.

[Brief explanation of the drawing]

1 is a side view of a welding apparatus using the welding roller shown in FIG. 2, and FIG. 2 is a side view of the welding roller according to the present invention. 12-m-protective layer, 14-m-resistive heating layer, 16--core, 19A, 19B-m-conductive annular element. (4 others) FIG. 1

Claims (1)

[Claims] 1. An electrophotographic fusing roller having a core, a resistive heating layer connectable to a power source, and an outer protective layer, wherein the core and the resistive heating layer are adjacent to each other, and the core A welding roller characterized in that the resistive heating layer is made of a thermally and electrically insulating material, and the resistance heating layer is made of a conductive material. 2. The welding roller according to claim 1, wherein the core is made of glass. 3. An inner core having an insulating outer surface, an outer protective layer supported on the outside of the insulating outer surface, a resistance heating layer formed between the outer protection layer and the inner core, and the resistance heating layer. conductive means for connecting the welding roller to a power source, the welding roller having a cylindrical shape adjacent to an end of the core and substantially continuous with the insulating outer surface. a conductive annular element forming a surface, the cylindrical surface being in contact with the inner surface of the resistance heating layer; and means for electrically connecting the conductive annular element to a power source. A welding roller comprising: