JPH0816014A - Heat roller - Google Patents

Abstract

PURPOSE:To prevent the joining failure of a heat radiating resistor layer, cause no peeling of the layer, and improve the reliability of a heat roller with a simple structure by making the heat roller composed of conductive pinching members and a supplying electrode; the conductive pinching members are composed so as to pinch and be joined to at least end parts of a cylindrical substrate and are made possible to come into contact with a heat radiating resistor layer and the heat radiating resistor layer is composed so as to slide on the conductive pinching members. CONSTITUTION:A heat roller 1 is manufactured by forming a heat radiating resistor layer 4 on the circumferential face of a cylindrical substrate 2 through an electrically insulating layer 3 and further forming a peeling layer 5. In one of pinching members 6, which are metal flanges to pinch the heat roller 1 at both ends, a projected part 6a is formed pushed into the cylindrical substrate. The pinching members 6 come into contact with the heat radiating resistor layer 4 through a conductive layer 9, a conductive adhesive 10 is applied so as to cover the conductive layer 9, and thus the pinching members 6 and the heat radiating resistor layer 4 are put in electrically continuity state. Further, the heat roller 1 has a supplying electrode 8 connected with an electric power source of a fixing apparatus and composed so as to slide on the tip surfaces of the pinching members 6. Consequently, without using a ring-like electrode, fixing can be carried out for a long time.

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, a printer, etc. The present invention relates to an electrode for supplying an electric current to a heat roller having a heating resistance layer laminated thereon.

[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 performed by a heat roller having a heating resistance layer formed on the peripheral surface of a metal cylindrical substrate with an electric insulation layer interposed therebetween, thereby shortening the rise time to the fixing temperature, and Techniques for keeping the surface temperature uniform have 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 bonding force between the respective layers of the cylindrical substrate, the insulating layer, and 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 cylindrical substrate and the electric insulating layer become problems, and the hardness Depending on the selection of a low material, thick coating of the electrical insulation layer on the cylindrical substrate generally weakens the bonding force between the heating resistance layer and the electrical insulation layer, resulting in the retention of the ring electrode. It will be difficult.

Therefore, this may cause defective bonding, peeling due to long-term use and cause defective fixing, and also increase the rise 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, there is a problem in that only limited thicknesses and types of electrical insulators can be used, the degree of freedom in selection is lost, and material selection and process control are costly.

The present invention has been made in view of the above-mentioned drawbacks, and an object of the present invention is to provide a heat roller capable of fixing toner for a long period of time without separately using a ring-shaped electrode.

Another object of the present invention is to provide a heat roller which has a simple structure and which is highly reliable and does not cause defective bonding or peeling of the heating resistance layer.

[0010]

In order to solve the above-mentioned problems, the heat roller of the present invention is constructed such that a heating resistance layer is laminated around a cylindrical substrate and an electric current can be supplied to the heating resistance layer. In the heat roller, a conductive sandwiching member that is sandwiched and coupled at at least one end of the cylindrical base body and is configured to be in contact with the heat generating resistance layer, and the heat generating resistance layer configured to be slidable on the conductive sandwiching member. It is composed of a supply electrode for supplying a current to.

[0011]

According to the above construction, since the metal flange is integrally fixed to the cylindrical substrate and the flange is in contact with and firmly fixed to the heat generating resistance layer, the heat generating resistance layer and the current are prevented from flowing. A strong joining force is obtained between the supply flanges, and no peeling of layers occurs.

[0012]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating the configuration of a fixing device. Reference numeral 1 is a heat roller of the present invention. A heating resistance layer 4 is laminated on a peripheral surface of a cylindrical substrate 2 with an electrical insulating layer 3 interposed therebetween, and a peeling layer 5 is further provided. Stacked.

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.

As a material for the cylindrical substrate 2 constituting the heat roller 1, a conductive material is preferable because it can be formed at a low cost, and specifically, aluminum, aluminum alloy, copper,
A metal having good conductivity such as copper alloy, iron or iron alloy can be used.

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. Such an organometallic polymer itself has a relatively low hardness, has flexibility, and can withstand a certain amount of blistering, so that no cracks or cracks occur, and the coefficient of thermal expansion is similar to that of a metal cylindrical substrate. Therefore, it is possible to obtain the 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. The degree of freedom in selecting the substrate is increased, the thickness of the substrate can be reduced, the substantial heat capacity is reduced, and the rise time of the fixing device is further shortened.

The heating resistance layer 4 is formed of a paste containing a metal powder such as RuO ₂ , Ni-Cr alloy, Ni, Cr, Cu or the like. 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 features of the present invention will be described in detail. Figure 2
Shows an enlarged end sectional view of the layer structure of the heat roller 1. 6
Is a metal flange that holds both ends of the heat roller,
One of the holding members is formed with a protrusion 6a and is press-fitted into the cylindrical base body 2. Here, when the cylindrical substrate 2 is made of metal, another flange may be fixed via the insulating layer 3 as shown in the figure. Further, the flange 6 is in contact with the heating resistance layer 4 via the conductive layer 9, and a conductive adhesive is applied so as to cover the conductive layer 9, so that the flange 6 and the heating resistance layer 4 are covered.
Is in conduction. As the material of the flange, the material shown for the cylindrical base 2 can be used.

Reference numeral 8 denotes a supply electrode which is connected to the power source of the fixing device and which can be rubbed against the top surface of the flange, and can supply an electric current to the heating resistance layer 4 through the flange 6 and the conductive layer 9 described above. Is configured. Although the supply electrode 8 is configured to be in contact with the top surface, the supply electrode 8 is not limited to this and can be contacted with any outer peripheral surface of the flange 6. Reference numeral 7 is a bearing of the heat roller 1.

As an example of manufacturing such a heat roller, a cylindrical base body 2 in which both ends are electrically insulated by flanges 6 and press-fitted and sandwiched is provided.
Is roughened by chemical etching in advance, an organometallic polymer is applied onto the cylindrical substrate 2 to form an electric insulating layer 3, and then a Ni heating resistance layer 4 is formed by a sputtering process using nichrome. To do. After that, the surface of the heat roller 1 is applied as a release layer 5 with a fluororesin to complete the process.

[0021]

According to the present invention, the metal flange is integrally fixed to the cylindrical substrate and fixed, and the flange is brought into contact with the heating resistance layer to serve as the conventional ring-shaped electrode. Even if a ring-shaped electrode is used, problems such as defective flange joining and peeling can be prevented, and a highly reliable heat roller can be provided. Further, with this configuration, the degree of freedom in selecting the material of the electric insulating layer is increased, and the processing control of the electric insulating layer can be roughly performed.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of a heat roller of the present invention.

FIG. 2 is an enlarged view of a main part of the heat roller of the present invention.

[Explanation of symbols]

 1: Heat roller 2: Cylindrical substrate 3: Electric insulating layer 4: Heat resistance layer 5: Release layer 6: Flange 6a: Protrusion 7: Bearing 8: Supply electrode 9: Conductive layer 10: Conductive adhesive

Claims (1)

[Claims] 1. A heat roller configured such that a heat generating resistance layer is laminated around a cylindrical base, and a current can be supplied to the heat generating resistance layer. The heat roller is sandwiched and bonded at least at one end of the cylindrical base and the heat generation is performed. A heat roller comprising: a conductive sandwiching member configured to be capable of contacting the resistance layer; and a supply electrode configured to be slidable on the conductive sandwiching member and supplying an electric current to the heating resistance layer.