JPH02131276A - Heat fixing roll device for electrophotographic device - Google Patents

Abstract

PURPOSE:To prevent a heat roll from deforming and deterioration with temperature and to improve its durability by making a heat insulation layer of hard heat-resisting foamed resin. CONSTITUTION:The heat roll 11 is formed by laminating the heat insulation layer 15, a resistance heat generation layer 17 made of metal connected to an external power source at axially end parts, and a protection layer 20 made of fluororesin on a metallic rotary shaft 13 in this order from the center to the outer periphery. Then, the heat insulation layer 15 of the heat roll 11 is molded out of foamed phenol resin as hard heat-resisting resin and many voids are formed in the foamed phenol resin to give the heat insulation layer 15 excellent heat insulation effect. Further, the phenol resin is hard, so the rigidity of the heat insulation layer 15 is also secured. Consequently, the heat roll is prevented from deforming and deteriorating and its durability is improved.

Description

Detailed Description of the Invention [Object of the Invention] <Industrial Field of Application> The present invention relates to a heat fixing method for an electrophotographic apparatus in which a transfer means is heated and pressurized using a pair of rolls in order to fix a mapped image. Relating to a roll device.

Conventional technology> Conventionally, in a heat fixing roll device that transfers toner to a transfer medium such as paper and then fixes it in an electrophotographic device using an electrophotographic process such as a copying machine, a heating roll and a pressure roll are used. The transfer means is passed through the nip where both rolls touch each other, and the toner is heated and pressed onto the transfer means at the same time. Conventionally, it takes a relatively long time for the heated rolls to rise in temperature. Because it takes a long time, for example, the patent application filed in 1986-5 by the same applicant
No. 7279 discloses that a heating roll is provided with a heat insulating/elastic layer made of an elastic material such as silicone foam rubber, and a resistance heating layer which may be made of metal is formed over the entire surface of the heat insulating/elastic layer. structure is proposed. According to this structure, the fixing operation can be performed by heating only the resistance heating layer, so that the time required to raise the temperature of the heating roll is shortened.

Therefore, since the heat insulating/resilient layer is sealed between the rotating shaft and the resistance heating layer, and expands more than the resistance heating layer when the temperature rises, the resistance heating layer There is a problem in that the heat insulating/resilient layer deforms when the temperature drops due to pressure on the heat insulating/resilient layer and the gas inside the layer being forced out. Furthermore, there was also the problem that the silicone foam rubber, etc. of the sealed heat insulating/resilient layer deteriorated due to expansion and contraction due to temperature changes of the heating roll.

<Problems to be Solved by the Invention> In view of the problems of the prior art, the main object of the present invention is to solve the above-mentioned heat-insulating layer in a heating roll having an internal heat-insulating layer and a resistance heating layer on the surface. Without sacrificing the insulation effect,
Another object of the present invention is to provide a heat fixing roll device for an electrophotographic device in which the layer is not deformed or deteriorated and its durability is improved.

[Structure of the Invention] <Means for Solving the Problems> According to the present invention, the object is to pass a transfer means between a heating roll and a pressure roll that rotate in close contact with each other, and to A heat fixing hole device for an electrophotographic apparatus for fixing a mapped image on the transfer receiving means, wherein the heating roll includes a rotating shaft, a heat insulating layer layered on the surface of the rotating shaft, and a surface of the heat insulating layer. The present invention is achieved by providing a heat fixing roll device for an electrophotographic apparatus, characterized in that the heat insulating layer is made of a foamed heat-resistant hard resin.

As described above, by using heat-resistant hard resin for the heat-insulating layer, its rigidity is improved, and the large number of cavities created by foaming this heat-resistant hard resin improves the heat-insulating properties of the heat-insulating layer. Secured.

<Embodiments> Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram of an electrophotographic apparatus showing a first embodiment based on the present invention.

The rotatable photosensitive drum 1 has an outer peripheral surface plated with selenium. A charging section 2, a photosensitive section 3, a developing section 4, a transfer section 5, a cleaning section 6, and a static eliminating section 7 are provided along the outer peripheral surface of the photosensitive drum 1 in this order. Further, a fixing section 8 is provided downstream in the direction in which the transfer paper 9 is carried out from the transfer section 5, that is, in the direction of arrow A.

When the photosensitive drum 1 rotates in the direction of arrow B in FIG. 1, the surface of the drum passes through a charging section 2 consisting of corona charging means, and as a result, the drum surface reaches a uniform potential of about 700 volts. charged. Next, the surface portion of the photosensitive drum 1 passes through an exposure section 3, and a latent image corresponding to the shape of the subject is formed by exposure. Then, toner conveyed to the developing section 4 by a roller (not shown) adheres to the surface of the photosensitive drum 1 in correspondence with the latent image. Further, in the transfer section 5, the transfer paper 9, which is conveyed in the direction of arrow A from the right side in FIG.
At the same time as being charged by a, the toner adhering to the surface portion of the drum 1 is transferred onto the paper 9. The surface portion of the photosensitive drum 1 after the toner has been transferred passes through a cleaning section 6, and residual toner is cleaned off. And a static eliminator 7 consisting of an exposure lamp
At this point, the electric potential is removed to a substantially uniform potential in the axial direction, and the above process is repeated again. On the other hand, the toner transferred to the paper 9 is heated and pressed onto the paper 9 at the same time in the fixing section 8, whereby the image is fixed on the paper 9.

FIG. 2 is an enlarged sectional view of the fixing section 8 of FIG. 1.

The fixing unit 8 includes a pressure roll 10 that is rotationally driven by a driving means (not shown) and a heating roll 11 that is driven by being in close contact with the pressure roll at a contact portion 12. The heating roll 11 has, from its center to its outer periphery, a rotating shaft 13 made of metal, a heat insulating layer 15 to be described later, and a resistance heating layer 17 made of metal connected to an external power source (not shown) at its axial end. A protective layer 20 made of fluororesin is laminated in this order. In addition, a heat insulating layer 15 and a resistance heating layer 17
An adhesive layer is provided between each layer of the protective layer 20. This adhesive layer is a layer for preventing the resistance heating layer 17 and the protective layer 20 from peeling off when both the rolls 1o and 11 are operated.

On the other hand, the pressure roll 10 includes a metal rotating shaft 21 and a rubber roll 22 fitted around the outer periphery thereof.

Incidentally, in reality, a spiral slit may be formed on the circumferential surface of the resistance heating layer 17.

As clearly shown in FIG. 2, the heat insulating layer 15 of the heating roll 11
is made of foamed and molded phenolic resin as a heat-resistant hard resin. By forming a large number of cavities inside the foamed phenolic resin, a suitable heat insulating effect can be obtained for the heat insulating layer 15. Furthermore, since the phenol resin is hard, the rigidity of the heat insulating layer 15 can also be ensured.

According to this embodiment, since the amount of deformation in the radial direction of the heating roll 11 is small, the base resin layer provided adjacent to the resistance heating layer in order to reinforce the resistance heating layer in the conventional heating roll is not necessary. I don't.

In this example, phenol resin was used for the heat insulating layer 15, but polyether ether ketone resin (PEEK), polyether sulfone resin (PES), melamine resin, polyimide resin, polyphenylene sulfide resin (P
Any heat-resistant hard resin such as PS) may be used.

[Effects of the Invention] As described above, according to the present invention, by using the foamed heat-resistant hard resin for the heat-insulating layer of the heating roll, the rigidity of the heat-insulating layer can be improved, and the foamed heat-resistant hard resin is Due to the large number of empty rooms created, insulation properties can be ensured. Therefore, deformation and deterioration of the heating roll due to temperature changes can be prevented, and the durability of the heating roll is improved. From the above, the effects of the present invention are extremely large.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an electrophotographic apparatus showing a first embodiment based on the present invention. FIG. 2 is an enlarged sectional view of the main part of FIG. 1. 1... Photosensitive drum 2... Charging section 3... Exposure section 4... Developing section 5... Transfer section
5a... Charging section 6... Cleaning section 7... Static elimination section 8... Fixing section 10... Press roll 12... Contact section 15... Heat insulating layer 20... Protective layer 22 ... Rubber mouth ring 9 ... Transfer paper 11 ... Heating roll 13 ... Rotating shaft 17 ... Resistance heating layer 21 ... Rotating shaft

Claims (2)

[Claims] (1) A heat fixing roll device of an electrophotographic apparatus for fixing an image of a subject on the transfer means by passing a transfer means between a heating roll and a pressure roll that rotate in close contact with each other, The heating roll has a rotating shaft, a heat insulating layer laminated on the surface of the rotating shaft, and a resistance heating layer laminated on the surface of the heat insulating layer, and the heat insulating layer is made of a foamed heat-resistant hard resin. A heat fixing roll device for an electrophotographic device, characterized in that: (2) Claim 1, wherein the surface of the pressure roll is softer than the surface of the heating roll.
A heat fixing roll device for an electrophotographic apparatus as described in 2.