JPH02220086A - Heat fixing roll device for electrophotographic device - Google Patents

Abstract

PURPOSE:To uniformly heat a resist heating layer and to uniformly rise the temperature of a heating roll by separately burrying resist heating wire in a slit space of the resist heating layer or providing the resist heating wire on the top part of the space. CONSTITUTION:For the resist heating layer 16, a resist heating strip 17 composed of the strip of nichrome foil is wound and adhered spirally on the surface of a heat insulating layer 15 from an end in the axial line direction to the other end. The slit space 18 is made around spirally between the space which the resist heating strip 17 of the resist heating layer 16 adjoin each other in the axial line direction. In the space 18, the resist heating wire 19 composed of the nichrome wire coated with insulating material is burried. Since the resist heating wire 19 is separately burried in the space 18, the space part is also suitably heated.

Description

[Detailed Description of the Invention] [Object of the Invention] <Industrial Application Field> The present invention relates to a heat fixing roll of an electrophotographic apparatus that heats and pressurizes a transfer means with a pair of rolls in order to fix a mapped image. Regarding equipment.

<Prior Art> 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. They are placed in close contact with each other, and 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, but conventionally it takes a relatively long time for the heated rolls to heat up. For example, in Japanese Patent Application No. 63-57279 filed by the same applicant, a heating roll is provided with a heat insulating layer such as silicone foam rubber, and the surface of this heat insulating layer is coated in the axial direction from one end to the other end. A structure has been proposed in which a resistance heating layer is formed having slit-like voids extending spirally toward the surface. According to this structure, the above-described fixing process can be carried out by raising the temperature of only the heat generating layer, so that the time required to raise the temperature of the heating roll is shortened.

<Problems to be Solved by the Invention> In the above structure, when forming a resistance heating layer by spirally wrapping a band-shaped foil around the surface of the heat insulating layer, if the slit-shaped void is made wide, the On the other hand, the above-mentioned slit-like voids do not generate heat because it is necessary to make the surface of the resistance heating layer uniform in hardness and to raise the temperature uniformly over the entire surface of the core layer in order to prevent uneven fixing. It is desirable to make it as narrow as possible.

The present invention was created in view of these problems, and its main purpose is to make it possible to equalize the hardness of the surface of a heating roll having a resistance heating layer and to raise the temperature uniformly over the entire surface. It is an object of the present invention to provide a heat fixing roll device for an electrophotographic device that is easy to manufacture.

[Structure of the Invention and Means for Solving the Problems] According to the present invention, the second 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 transfer the image of a subject. In a heat fixing roll device of an electrophotographic apparatus for fixing a mapped image on the transfer target means, the heating roll has a resistor having a slit-like gap extending spirally from one end to the other end in the axial direction. It is characterized by comprising a heating layer, and a resistance heating wire that is insulated from the resistance heating layer and is disposed in or near the slit-like gap and extends along the gap. This is accomplished by providing a heat fusing roll device for an electrophotographic device.

As described above, by burying an insulated resistance heating wire in the slit-like void of the resistance heating layer, or by arranging a bare wire resistance heating wire at the upper position of the void, the void portion can be heated. The hardness of the resistive heat generating layer and the other portions is generally uniform, and the temperature of the resistance heating layer including the void portion is uniformly increased over the entire surface.

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

FIG. 1 shows the configuration of an electrophotographic apparatus to which the present invention is applied.

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 is charged to a uniform potential of about 700 volts. be done. Next, photosensitive drum 1
The surface portion of the image passes through the exposure section 3, and a latent image corresponding to the shape of the subject is formed by exposure. Then, toner conveyed to a carrier (not shown) in the developing section 4 adheres to the surface of the photosensitive drum 1 in correspondence with the latent image. Furthermore, the transfer section 5
At this time, the transfer paper 9 conveyed from the right side in the direction of arrow A in FIG.
At the same time as the drum 1 is charged, the toner attached to the surface of the drum 1 is transferred to 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. Then, in the static eliminator 7 consisting of an exposure lamp, the static electricity is removed to approximately a negative 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, so that 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. From the center to the outer circumference, the heating roll 11 includes a rotating shaft 13 made of metal, a heat insulating layer 15 made of a porous ceramic material, and a resistance heating layer 16 connected to an external power source (not shown) at an axial end thereof. A protective layer 21 made of fluororesin is laminated in this order. Moreover, an adhesive layer is provided between each layer of the heat insulating layer 15, the resistance heating layer 16, and the protective layer 21. This adhesive layer is a layer for preventing the heat insulating layer 15, the resistance heating layer 16, and the protective layer 21 from peeling off from each other during operation of both rolls 10.11.

On the other hand, the pressure roll 10 has a rotating shaft 22 made of a metal tube,
It has a resilient layer 23 made of an elastomer material, which may be synthetic rubber, wrapped around the rotating shaft. In fact, only a metal tube may be used for the pressure roll 10, and in that case, the heat insulating layer 15 of the heating roll 11 is preferably made of a foamed elastomer material, which may be silicone foam rubber.

As shown in FIG. 3 when the heating roll 11 is viewed from the side, the resistance heating layer 16 has a width of 511I11 to 15IllI1.
A resistance heating zone 17 made of a band-shaped nichrome foil having a thickness of 20 μm to 80 μm is wound spirally around the surface of the heat insulating layer 15 from one end in the axial direction to the other end, and is bonded to the heat insulating layer 15. A slit-like void 18 is spirally formed between adjacent portions of the resistance heating zone 17 of the resistance heating layer 16 in the axial direction. Furthermore, a resistance heating wire 19 made of an insulating coated nichrome wire is buried in the cavity 18 . The resistance heating wire 19 extends along the gap 18 toward both ends of the heating roll 11 in the axial direction.

Note that the adhesive layer 20 between the resistance heating layer 16 and the protective layer 21
is made of a heat-resistant resin whose thermal conductivity is slightly lower than that of the resistance heating layer 16, and this heat-resistant resin also fills the portions of the void 18 where there is no resistance heating wire 19.

In this way, even if the resistance heating layer 17 is wound around the resistance heating layer 16 so that the gap 18 is relatively wide, the resistance heating wire 19 is separately buried in the gap 18, so that the gap portion also becomes large. It starts to generate heat appropriately. Furthermore, unlike the case where the voids 18 are simply filled with heat-resistant resin, the hardness of the surface of the heating roll 11 is also made uniform.

FIG. 4 is a diagram similar to FIG. 2 showing a second embodiment based on the present invention, and similar parts are given the same reference numerals and detailed explanation thereof will be omitted.

In this embodiment, the resistance heating wire 29 is not coated with insulation, but is embedded and wound within the adhesive layer 20 at a position outside the gap 18 and at a certain distance from the resistance heating zone 17. Therefore, in this embodiment, the resistance heating wire 29 and the resistance heating zone 17 are insulated by the resin material of the adhesive layer 20.

In reality, for example, the resin material used for the adhesive layer 20 is first filled in the void 18 and applied to the surface of the resistance heating zone 17 up to the position shown in the imaginary line, and after wrapping the resistance heating wire 29, the wire is covered. It is preferable to apply a resin material to the adhesive layer 20 to form the adhesive layer 20. The other structure is the same as that of the first embodiment.

[Effects of the Invention] As described above, according to the present invention, the resistance heating layer can be heated by embedding the resistance heating wire separately in the slit-like gap of the resistance heating layer or by providing the resistance heating wire above the gap. The heating roll generates heat uniformly over its entire surface, that is, the temperature of the heating roll rises uniformly over its entire surface. Furthermore, since the hardness of the slit-like gap portion and other portions is generally uniform, the adhesion to the transfer target means is improved, and the fixability to the transfer target means is improved.

From the above, the effect is significant.

[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. FIG. 3 is a partially cutaway side view of only the heating roll shown in FIG. 2. FIG. 4 is a diagram similar to a portion of FIG. 3 showing a second embodiment according to the invention. 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 9...Transfer paper 10
...Crimping roll 11...Heating roll 12...
Contact portion 13... Rotating shaft 15... Heat insulation layer
16... Resistance heating layer 17... Resistance heating zone 19... Resistance heating wire 21... Protective layer 23... Resilience layer 18... Gap 20... Adhesive layer 22... Rotating shaft 29...resistance heating wire

Claims (2)

[Claims] (1) In 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 includes a resistive heating layer having a slit-like void extending spirally from one end in the axial direction to the other end, and a resistive heating layer that is insulated from the resistive heating layer and inside the slit-like void or the slit-like void. A heat fixing roll device for an electrophotographic apparatus, comprising a resistive heating wire disposed near the gap and extending along the gap. (2) The electronic device according to claim 1, wherein the resistance heating layer is formed by winding a resistance heating zone around the heating roll in a spiral shape from one end in the axial direction to the other end. Heat fixing roll device for photographic equipment.