JPH07263120A - Heat roller - Google Patents

Abstract

PURPOSE:To provide a long-time usable and highly reliable heat roller in a simple structure in which no bonding failure occurs between a ring electrode and a heating resistance layer. CONSTITUTION:A heat roller 1 has a heating resistance layer 4 laminated around a conductive cylindrical base 2 via an electrically insulating layer 3 and a ring electrode 7 adhered along the periphery of the heating resistance layer 4 to supply a current thereto. The ring electrode 7 and the cylindrical base 2 to be electrically insulated therfrom are made into one unit and fixed each other. In this way, a degree of freedom of selecting material for the electrically insulating layer 3 is increased without taking costs in selecting the material and managing processes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat roller of a fixing device used in an electrophotographic image forming apparatus such as an electrophotographic copying machine, a facsimile and a printer, and more particularly to an electrically insulating layer on a cylindrical substrate. The present invention relates to an electrode that supplies a current to a heat roller having a heating resistance layer laminated therethrough.

[0002]

2. Description of the Related Art In an image forming apparatus using an electrophotographic apparatus, a toner image is formed on the surface of a photoconductor, the toner image is transferred onto a sheet of paper, and the toner on the transfer sheet is heated and melted to adhere to the sheet. Although a heat fixing method of fixing by means of a heat roller has been known in the past, a heat roller method of fixing by means of a heat roller and a press roller is now predominant among the heat fixing methods.

Among the heating methods using the heat roller, a method of indirectly heating the toner by installing a halogen lamp or the like on the central axis of the roller to heat the roller is conventionally known. Because it is required to heat the halogen lamp with sufficient heat capacity in order to deal with the rapid temperature change of the roller surface due to, and the non-uniformity of temperature in the roller longitudinal direction due to different paper sizes. However, there is a problem that it takes too much time (rise time) to reach the printable temperature.

In order to solve such a problem, fixing is carried out by a heat roller having a heating resistance layer formed on the peripheral surface of a metallic cylindrical substrate with an electric insulation layer interposed therebetween, thereby shortening the rise time to the fixing temperature. Further, a technique for keeping the surface temperature uniform has been proposed (JP-A-55-72390, JP-A-64-86185).

[0005]

However, as a current supply means of such a technique, a ring-shaped electrode is adhered to the periphery of the heating resistance layer with a conductive adhesive so that the current can be supplied. Then, the substrate, insulating layer,
Bonding force between the layers of the heating resistance layer is strongly required.

That is, even if the joining force between the heating resistance layer and the ring-shaped electrode is secured, the joining force between the heating resistance layer and the electric insulating layer and the joining force between the substrate and the electric insulating layer become problems, and the electric insulating layer is a problem. If a thick coating is applied to the substrate, the bonding force between the heating resistance layer and the electrical insulation layer will generally weaken, depending on the choice of a material with low hardness, resulting in difficulty in holding the ring-shaped electrode. Become. Therefore, this may cause defective bonding and peeling due to long-term use, which may cause defective fixing and also increase the rising time. On the other hand, if the electric insulation layer is made thin, the bonding force also increases, but the possibility of causing insulation failure increases. Therefore, only the limited thickness and type of the electrical insulator can be used, the degree of freedom in selection is lost, and the cost for material selection and process control increases.

The present invention has been made in view of the above-mentioned drawbacks, and increases the degree of freedom in selection of the electric insulating layer, and with a simple structure, does not cause a defective joint between the ring-shaped electrode and the heating resistance layer, and is reliable for a long time. An object is to provide a heat roller having high properties.

[0008]

In order to solve the above problems, in the heat roller of the present invention, a heat generating resistance layer is laminated around an electrically conductive cylindrical substrate with an electrically insulating layer interposed therebetween, and the heat generating resistance is A heat roller comprising a plurality of ring-shaped electrodes adhered along the periphery of a layer, and a supply electrode configured to be capable of supplying an electric current to the heating resistance layer while rubbing the ring-shaped electrodes. The ring-shaped electrode is integrally fixed to the conductive cylindrical substrate so that the electrode and the conductive cylindrical substrate are electrically insulated.

Among them, as means for integrally fixing, an insulative projection inserted into a hole penetrating from the cylindrical base to the heating resistance layer is fixed to the inner circumference of the cylindrical base, and further, the ring shape is formed. It is preferable to use one in which the concave portion formed on the fixing surface of the electrode and the tip of the protrusion protruding from the hole are fitted and fixed to each other.

Further, as another means for integrally fixing, a convex protrusion is provided on the surface of the cylindrical substrate, and a convex portion is formed by laminating the layers on the cylindrical substrate including the protrusion. Alternatively, the recessed portion formed on the fixing surface of the ring-shaped electrode may be fitted and fixed to each other.

[0011]

According to the above structure, the ring-shaped electrode and the conductive cylindrical substrate are integrally fixed to each other so as to be electrically insulated, so that the ring-shaped electrode is firmly attached to the rotating cylindrical substrate. A strong bonding force can be obtained between the fixed heating resistance layer and the ring-shaped electrode, and it is not necessary to consider the thickness and type of the electrical insulating layer for increasing the bonding force.

[0012]

Embodiments of the present invention will be described with reference to the drawings. FIG. 4 is a view for explaining the structure of the fixing device, in which 1 is a heat roller of the present invention, in which a heat generating resistance layer 4 is laminated on the peripheral surface of a conductive cylindrical substrate 2 with an electric insulating layer 3 interposed therebetween, and peeled off. Layer 5 is laminated.

Reference numeral 10 denotes a press roller, which has a metal core 12
Is formed in a state in which an elastic body 11 such as a silicon sponge is coated on the surface thereof, is supported by bearings (not shown) at both ends thereof and is rotatably provided, and rotates according to the rotation of the heat roller 1.

A sheet conveying path is formed by guide plates 23 at both ends of a nip portion formed by the heat roller 1 and the press roller 10, and is formed on the surface of the sheet 20 conveyed to the sheet conveying path 23. The toner image 21 is fixed by applying pressure by the press roller 10 and heating by the heat roller 1 almost at the same time. A temperature sensor for temperature control is provided around the heat roller 1.

The material of the conductive cylindrical substrate 2 constituting the heat roller 1 is aluminum, aluminum alloy,
A metal having good conductivity such as copper, copper alloy, iron, or iron alloy can be used. In particular, in Example 1 described later, it is preferable to use a ductile material such as aluminum, and in Example 2, a metal or the like that can be punched at low cost is preferable.

Although an organic metal polymer is used for the electric insulating layer 3, the present invention is not limited to this, and it can be used for a material having a high hardness such as glass, but the present invention is a material having a high insulating property and a relatively low hardness. It is best used for. The organometallic polymer itself has relatively low hardness, has flexibility, and can withstand a certain amount of blistering, so that no chipping or cracking occurs, and the coefficient of thermal expansion is similar to that of the metal cylindrical substrate. Therefore, it is possible to obtain the function and effect that the electric insulation layer 3 is not cracked due to the difference, and can be formed by applying an uncured organometallic polymer and heating and curing at a relatively low temperature. Further, the degree of freedom in selecting the substrate is increased, the thickness of the substrate can be reduced, the actual heat capacity is reduced, and the rise time of the fixing device is further shortened.

The heat generating resistance layer 4 is formed of a paste containing a metal powder such as RuO ₂ , Ni-Cr alloy, Ni, Cr, Cu. The peeling layer 5 covers the heat generating resistance layer 4 and is made of a fluororesin such as PFA or PTFE in order to prevent the toner from adhering to the heat roller side during transfer.

Next, the first embodiment of the present invention will be described in detail. FIG. 1A is an enlarged cross-sectional view of an end portion of the layer structure of the heat roller 1 shown in FIG. Reference numeral 7 denotes a metallic ring-shaped electrode provided at the end portion of the heat roller and fixed to the heating resistance layer 4, and is provided at both ends of the heat roller 1 although not shown. As shown in FIG. 1B, the electrode 7 has a recess 7c on the surface of the ring-shaped electrode 7 that contacts the heating resistance layer 4.
And the convex projections formed on the conductive cylindrical substrate 2 shown below are fitted to each other so that the ring-shaped electrode 7 and the conductive cylindrical substrate 2 are bonded by the conductive adhesive 7a or the plated layer 7b. And is fixed by the conductive adhesive 7a. Reference numeral 9 is a supply electrode which is connected to a power source of the apparatus main body (not shown) and which is capable of supplying a current to the heating resistance layer 4 while rubbing the ring-shaped electrode 7 thereof. Further, 8 is a bearing, which is a conductive substrate 2
The heat roller 1 is rotatably installed in contact with and supported by the end portion.

Reference numeral 2a is a convex protrusion protruding from the surface of the cylindrical substrate, and each of the electric insulating layer 3, the heat generation resistance layer 4, and the peeling layer 5 is stacked around the cylindrical substrate 2 including this surface shape. There is. As an example of manufacturing such a heat roller, the surface of the conductive cylindrical substrate 2 is roughened in advance by chemical etching, and an organometallic polymer is applied onto the conductive cylindrical substrate 2 to form an electrically insulating layer 3, and thereafter. The heat generating resistance layer 4 of Ni is formed by the sputtering process using nichrome. At this time, the above-mentioned layers are also laminated on the convex projection 2a, and the concave portion of the ring-shaped electrode is fitted therein by a conductive adhesive or other plating treatment, and then the surface of the heat roller 1 is made of fluorine. It is completed by applying resin. The ring-shaped electrode 7 is electrically insulated from the conductive cylindrical substrate 2 because the ring-shaped electrode 7 is interposed via the electrically insulating layer 3, and only the heating resistance layer 4 is effective without a current flowing into the substrate 2. Can be heated.

FIG. 2 relates to a second embodiment of the present invention, in which the layers laminated as described above extend from the cylindrical substrate 2 to the heat generating resistance layer 4 and through holes 2c through which projection forming members 2b to be described later penetrate. The projection forming member 2b is inserted into the hole 2c and fixed to the inner peripheral surface of the conductive cylindrical substrate 2. The protrusion forming member 2b is composed of a protrusion 21b and an abutting portion 22b, and is formed in a size that can fit into the recess of the ring-shaped electrode 7 described above. Also, the contact portion 22b
The contact surface is formed in a shape along the inner diameter of the conductive cylindrical substrate 2, and the protrusion forming member 2b is fixed to the conductive cylindrical substrate 2. Further, the protrusion forming member 2b is made of an insulating member, whereby the electrical insulation between the ring-shaped electrode 7 and the conductive cylindrical substrate 2 is maintained.

FIG. 3 relates to the third embodiment, and the second embodiment
The contact portion 22b of the protrusion forming member 2b used in this embodiment is a flat surface, and the other points are the same as those in the second embodiment. In this case, as shown in FIG. 3C, the inner peripheral surface with which the conductive cylindrical substrate 2 is in contact is flattened to prevent backlash when the protrusion forming member 2b is attached.

[0022]

EFFECTS OF THE INVENTION According to the present invention, the ring-shaped electrode and the conductive cylindrical substrate are integrally fixed so as to be electrically insulated, and are fixed to each other. Instead, a heat roller in which a heat generating resistance layer is laminated around a substrate via an electric insulation layer can be configured, the degree of freedom in selecting a material for the electric insulation layer is increased, and processing control of the electric insulation layer can be roughly performed.

Further, since the ring-shaped electrode is stably fixed to the heating resistance layer with a simple structure, it is possible to prevent the fixing failure even after long-term use.

[Brief description of drawings]

FIG. 1A is an explanatory view of a main part of a first embodiment of the present invention, and FIG. 1B is a sectional view of a ring-shaped electrode.

FIG. 2A is an explanatory view of a main part showing a second embodiment of the present invention. FIG. 2B is a configuration diagram of a projection forming member used in the second embodiment of the present invention.

FIG. 3A is an explanatory view of a main part showing a third embodiment of the present invention. FIG. 3B is a configuration diagram of a projection forming member used in the third embodiment of the present invention. Sectional explanatory drawing of an Example

FIG. 4 is a diagram illustrating an outline of a fixing device of the present invention.

[Explanation of symbols]

 1: Heat roller 2: Conductive cylindrical substrate 2a: Convex protrusion 2b: Protrusion forming member 2c: Hole 3: Electrical insulating layer 4: Heating resistance layer 5: Release layer 6: Supply electrode 7: Ring electrode

Claims (3)

[Claims] 1. A structure in which a heating resistance layer is laminated around a conductive cylindrical substrate with an electrical insulating layer interposed therebetween, and a current can be supplied to a ring-shaped electrode fixed along the circumference of the heating resistance layer. In the above heat roller, the ring-shaped electrode and the cylindrical substrate are integrated so as to be electrically insulated. 2. As a means for integrating the ring-shaped electrode and the cylindrical substrate, an insulating protrusion inserted into a hole penetrating from the cylindrical substrate to the heating resistance layer, and the ring-shaped electrode. The heat roller according to claim 1, wherein the concave portion formed on the fixing surface is fitted and fixed to each other. 3. A state in which convex protrusions are provided on the surface of the cylindrical substrate as a means for integrating the ring-shaped electrode and the cylindrical substrate, and the respective layers are laminated on the cylindrical substrate including the protrusions. 2. The heat roller according to claim 1, wherein the convex portion formed in 1) and the concave portion formed in the fixing surface of the ring-shaped electrode are fitted and fixed to each other.