JPH08272248A - Roll heater, fixing device and image forming device - Google Patents

Abstract

PURPOSE: To facilitate the constitution of a drum-like or hand-drum-like roll heater, and further to facilitate the constitution of a fixing device using the roll heater and an image forming device using the fixing device as wall. CONSTITUTION: A heating resistor layer 9 and electrodes 10a and 10b are formed on the outer peripheral part of a cylindrical or columnar substrate 8 which has electrical insulation and a uniform outside dimension over the enter length and a top film 11 is formed on the outer peripheral part 11 of the heating resistor layer 9, to constitute the roll heater 5. Then, the top film 11 is formed to such a shape that the thickness is gradually made larger as it goes to the central part from both end parts in the axial direction of the substrate 8. Moreover, the fixing device is constituted of the roll heater 5 and the image forming device is constituted of the fixing device, as well.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a roll heater and
The present invention relates to a fixing device and an image forming apparatus using this roll heater.

[0002]

2. Description of the Related Art Conventionally, an image forming process in an image forming apparatus such as a copying machine or a printer forms an electrostatic latent image by exposing the surface of a uniformly charged photoconductor on the basis of image data, A toner image is formed by developing the electrostatic latent image with toner, the toner image on the photoconductor is transferred to a sheet by a transfer unit, and the toner image transferred to the sheet can be fixed by a fixing device. It is common.

As a structure of the fixing device, a roll heater having a heat generating function and a pressure roller having a pressure function are arranged in parallel with each other, and the outer peripheral surfaces of the roll heater and the pressure roller have a predetermined pressure. It is common that they are brought into contact with each other.

Various means for improving the fixing performance of the fixing device have been proposed and put into practical use. For example, in order to prevent paper skew and wrinkles during fixing, the shape of the roll heater may be formed in a drum shape in which the central portion has a larger diameter than both end portions, or the central portion compared to both end portions. Is shaped like a drum with a small diameter.

Here, the structure of a conventional roller heater formed in a drum shape will be described with reference to FIG. The cylindrical substrate 1 is formed of an electrically insulating material such as ceramics or glass. The base 1 is
The drum-shaped base 1 is formed so that the central portion has a larger diameter than both ends, and the drum-shaped base 1 is formed by first forming a cylindrical base whose outer diameter is uniform over the entire length, and then
This is performed by polishing the outer peripheral surface of the base into a drum shape. A heat generating resistor layer 2 is formed on the outer peripheral portion of the base 1 with a uniform thickness, and electrodes 3a and 3b are formed on the outer peripheral portions of the heat generating resistor layer 2 at both ends of the base 1 in the axial direction. ing. Furthermore, the electrode 3 in the heating resistor layer 2
A part sandwiched between a and 3b and a part of the electrodes 3a and 3b are covered with an upper film 4 having a uniform thickness.

The formation process of the drum-shaped roll heater is similar to the case of forming the drum-shaped roll heater, and the outer peripheral surface of the cylindrical substrate whose outer diameter is uniform over the entire length is polished. Thus, a drum-shaped base body having a small diameter in the central portion is formed, and a heating resistor layer and electrodes are formed on the outer peripheral portion of the drum-shaped base body.

[0007]

In a conventional roller heater formed into a drum shape or a drum shape, the drum heater or drum shape is obtained by polishing the outer peripheral portion of a cylindrical substrate having an outer diameter that is uniform over the entire length. Since the base is formed into a strip shape, this polishing operation is troublesome and hinders the improvement in the productivity of the roll heater.

Therefore, an object of the present invention is to provide a drum-shaped or drum-shaped roll heater which is easy to manufacture, and a fixing device and an image forming apparatus using these roll heaters.

[0009]

A roll heater according to a first aspect of the present invention comprises a cylindrical or columnar substrate having an electrically insulating property and a uniform outer diameter over its entire length; formed on the outer peripheral portion of the substrate. A heat-generating resistor layer; electrodes formed on the outer peripheral portion of the heat-generating resistor layer at both ends in the axial direction of the substrate; and a portion covering the portion of the heat-generating resistor layer sandwiched by the electrodes and the substrate. And an upper film whose central portion is gradually thicker than both axial end portions thereof.

A roll heater according to a second aspect of the present invention is a cylindrical or columnar substrate having electrical insulation and having an outer diameter dimension that is uniform over the entire length; A lower film having a central portion that is gradually thicker than both axial end portions; a heating resistor layer formed on an outer peripheral portion of the lower film; and an outer periphery of the heating resistor layer at both axial end portions of the base. And an electrode formed on the part.

A roll heater according to a third aspect of the present invention includes a cylindrical or columnar substrate having electrical insulation and having an outer diameter dimension that is uniform over its entire length; A lower film whose both ends gradually become thicker than the axial center; a heating resistor layer formed on the outer periphery of this lower film; and an outer periphery of the heating resistor layer at both axial ends of the base. And an electrode formed on the part.

In each of the above inventions, the substrate is formed of a material having electrical insulation such as ceramics and glass, and the outer diameter is formed uniformly over the entire length. The upper and lower films are formed by screen-printing an insulating glass paste containing lead borosilicate glass, which has a high insulating property, as the main component, and this screen-printing is repeated in several layers and the upper part and the central part The thickness dimension is changed by printing only on the portion closer to the upper layer or by printing only on the portions on both ends as the upper layer is formed.

According to a fourth aspect of the present invention, there is provided a fixing device including the roll heater according to the first or second aspect, which is arranged parallel to the roll heater and has an outer peripheral surface facing the outer peripheral surface of the roll heater. And a pressure roller.

According to a fifth aspect of the present invention, there is provided a fixing device comprising: the roll heater according to the third aspect; pressure applied with the outer periphery of the roll heater opposed to the outer periphery of the roll heater. And a roller.

In each of the above inventions, making the outer peripheral surface of the roll heater and the outer peripheral surface of the pressure roller face each other includes the case where the outer peripheral surfaces directly contact each other.

An image forming apparatus according to a sixth aspect of the present invention includes means for forming a toner image on a photoconductor; transfer means for transferring the toner image formed on the photoconductor to a sheet; 5. The fixed toner image is fixed on the sheet.
Or a fixing device described in 5.

[0017]

According to the first aspect of the present invention, the heating resistor layer and the electrode are formed on the outer peripheral portion of the substrate whose outer diameter is uniform over the entire length, and the outer peripheral portion of the heating resistor layer is covered with the upper film. By making the upper film gradually thicker in the central portion than both axial ends of the substrate, the outer peripheral portion of the substrate is polished as in the conventional example, and the substrate has a drum shape in which the central portion has a large diameter. As compared with the case of forming the roll heater, the drum heater can be easily formed with high dimensional accuracy.

According to the second aspect of the present invention, the lower film is first formed on the outer peripheral portion of the substrate having the uniform outer diameter over the entire length, and the lower film is formed so that both axial end portions of the lower film are compared with the central portion. In order to form a heating resistor layer and electrodes on the outer peripheral portion of this lower film, the outer peripheral portion of the base is polished and the base is made into a drum shape whose central portion has a large diameter as in the conventional example. As compared with the case of forming the drum heater, the drum heater can be easily formed with high dimensional accuracy.

According to the third aspect of the present invention, the lower film is first formed on the outer peripheral portion of the substrate whose outer diameter dimension is uniform over the entire length, and the lower film has both end portions compared to the central portion in the axial direction of the substrate. Since the heating resistor layer and the electrode are formed on the outer peripheral portion of the lower film, the outer peripheral portion of the substrate is polished as in the conventional example to form a drum shape in which the central portion has a small diameter. As compared with the case, the drum heater can be easily formed with high dimensional accuracy.

In the invention of claim 4, claim 1
Alternatively, since the fixing device is formed by using the roll heater described in 2, the manufacturing of the fixing device becomes easy.

According to the invention of claim 5, claim 3
In order to form the fixing device using the roll heater described,
This makes the fixing device easy to manufacture.

According to the invention of claim 6, claim 4
Alternatively, since the image forming apparatus is formed using the fixing device described in 5, the image forming apparatus can be easily manufactured.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. 1 is a vertical sectional front view showing the roll heater 5, FIG. 2 is a vertical sectional side view showing a fixing device 6 using the roll heater 5, and FIG. 3 is a vertical sectional view showing an image forming device 7 using the fixing device 6. It is a schematic diagram.

The roll heater 5 is, as shown in FIG.
A cylindrical base body 8 made of a ceramic having an electrically insulating property is provided in the center thereof, and the base body 8 is formed so that its outer diameter dimension is uniform over the entire length.
A heating resistor layer 9 is formed on the outer peripheral portion of the base 8 with a uniform thickness. Further, electrodes 10a and 10b are formed on the outer peripheral portion of the heat generating resistor layer 9 at both ends of the base 8 in the axial direction.
Are formed. Also, the portion of the heating resistor layer 9 sandwiched between the electrodes 10a and 10b and the electrode 10
An upper film 11 is formed to cover a part of a and 10b.

The upper film 11 is formed by screen-printing an insulating glass paste containing lead borosilicate glass having a high insulating property as a main component, and the screen-printing is repeated in several layers and the upper layer is formed. By printing only on the portion closer to the central portion, the central portion is formed to have a thickness that is gradually thicker than the axial end portions of the base body 8. Since this insulating glass paste has fluidity, when it is screen-printed in multiple layers so that the central part becomes thicker, it does not become stepped at both ends, and it has a gentle slope. Become a state.

Therefore, by forming the upper film 11 in a shape in which the central portion is thicker than both end portions, the roll heater 5 has a drum-like shape in which the central portion has a larger diameter than both end portions.

As shown in FIG. 2, the fixing device 6 is arranged in parallel with the roll heater 5 and its outer peripheral surface is pressed against the outer peripheral surface of the roll heater 5 with a predetermined pressure. The pressure roller 12 is in contact with the pressure roller 12. The pressure roller 12 is formed of a cylindrical pressure cylinder 13 formed of an elastic body having heat resistance, and a film film 14 formed on the outer peripheral portion of the pressure cylinder 13.

The image forming apparatus 7 is, as shown in FIG.
A drum-shaped photosensitive member 16 that is rotationally driven at a predetermined speed is provided in a substantially central portion of the housing 15.
A charger 17, an exposure device 18, and a developing device 1 as means for forming a toner image on the surface of the photoconductor 16 are provided around
9 and a transfer corotron 21 which is a transfer unit for transferring the toner image formed on the surface of the photoconductor 16 to the paper 20.
Etc. are provided. Further, inside the housing 15, the fixing device 6 for fixing the toner image transferred onto the paper 20 onto the paper 20 is provided.

In such a structure, when the paper 20 passes between the photoconductor 16 and the transfer corotron 21, the toner image formed on the photoconductor 16 is transferred to the paper 20, and the toner image is transferred. The rolled paper 5 is the rolled paper 5.
The toner image is fixed on the sheet 20 when passing between the pressure roller 12 and the pressure roller 12.

Here, since the roll heater 5 is formed in a drum shape in which the central portion has a diameter that is gradually larger than both end portions, the sheet 20 is prevented from being skewed or wrinkled during this fixing. The fixing performance is improved.

Next, when the upper film 11 is formed, the insulating glass paste is divided into several layers and screen-printed to form the upper film 11 in a shape in which the central portion is gradually thicker than the both end portions. Therefore, the roll heater 5
The work for forming the drum shape becomes easy, the manufacturing cost is reduced, and the dimensional accuracy is improved.

Therefore, the formation of the fixing device 6 using the roll heater 5 and the image forming device 7 using the fixing device 6 are facilitated, and the manufacturing cost is reduced.

In the present embodiment, the base 8 formed in a cylindrical shape has been described as an example, but the shape of the base is not limited to a cylindrical shape, but a cylindrical shape. May be.

Next, a second embodiment of the present invention will be described with reference to FIGS. The same parts as those described in FIGS. 1 to 3 are designated by the same reference numerals, and the description thereof will be omitted. 4 is a vertical sectional front view showing the roll heater 22, and FIG. 5 is a fixing device 2 using the roll heater 22.
3 is a vertical sectional side view, and FIG. 6 is a schematic vertical sectional view showing an image forming apparatus 24 using the fixing device 23.

As shown in FIG. 4, the roll heater 22 is provided at its center with a cylindrical base 8 made of electrically insulating ceramics. The base 8 has an outer diameter dimension. It is formed uniformly over the entire length. A lower film 25 is formed on the outer peripheral portion of the base body 8, a heating resistor layer 9 is formed on the outer peripheral portion of the lower film 25 with a uniform thickness, and the heat generating resistor layer 9 is formed on both end portions of the base body 8 in the axial direction. Electrodes 10a and 10b are formed on the outer peripheral portion of the heating resistor layer 9. Also, the portion of the heating resistor layer 9 sandwiched between the electrodes 10a and 10b and the electrode 10a,
An upper film 26 that covers a part of 10b is formed with a uniform thickness.

Here, the lower film 25 is formed by screen-printing an insulating glass paste containing lead borosilicate glass having a high insulating property as a main component, and the screen-printing is repeated in several layers. By printing only on the portion closer to the center as the upper layer becomes
Is formed in a shape in which the central portion gradually becomes thicker than the both end portions in the axial direction. Since this insulating glass paste has fluidity, when it is screen-printed in multiple layers so that the central part becomes thicker, it does not become stepped at both ends, and it has a gentle slope. Become a state.

Therefore, in the roll heater 22 in which the heating resistor layer 9 and the upper film 26 are formed on the lower film 25 with a uniform thickness, the central portion of the roll heater 22 has a larger diameter than the both ends thereof. It becomes a drum shape.

As shown in FIG. 5, the fixing device 23 is arranged in parallel with the roll heater 22 and its outer peripheral surface is pressed against the outer peripheral surface of the roll heater 22 with a predetermined pressure. The pressure roller 12 is in contact with the pressure roller 12.

As shown in FIG. 6, the image forming device 24 is formed by providing a photosensitive member 16 and a means for forming a toner image, a transfer corotron 21, a fixing device 23 and the like in a housing 15. .

In such a structure, when the paper 20 passes between the photoconductor 16 and the transfer corotron 21, the toner image formed on the photoconductor 16 is transferred to the paper 20, and the toner image is transferred. The rolled paper 2 is the rolled paper 2.
The toner image is fixed on the sheet 20 when passing between the pressure roller 12 and the pressure roller 12.

Here, since the roll heater 22 is formed in a drum shape whose central portion gradually becomes larger in diameter than both end portions, the sheet 20 is prevented from being skewed or wrinkled at the time of this fixing. The fixing performance is improved.

Next, when the lower film 25 is formed, the insulating glass paste is divided into a number of layers and screen-printed to form the lower film 25 in a shape in which the central portion is gradually thicker than the both ends thereof. Then, since the drum heater 22 is formed by forming the heating resistor layer 9 and the upper film 26 on the lower film 25 to have uniform thickness, the roll heater 22 is formed in a drum shape. This facilitates the work to reduce the manufacturing cost and improves the dimensional accuracy.

Therefore, the formation of the fixing device 23 using the roll heater 22 and the image forming device 24 using the fixing device 23 are facilitated, and the manufacturing cost is reduced.

[0044]

According to the invention described in claim 1, a heating resistor layer or an electrode is formed on the outer peripheral portion of the substrate whose outer diameter is uniform over the entire length, and the upper film covering the heating resistor layer is provided at both ends. Since it is formed in a shape in which the central part gradually becomes thicker than
It is possible to easily form a drum-shaped roll heater whose central portion has a larger diameter than both ends, without any trouble, and therefore, it is possible to reduce the manufacturing cost and improve the dimensional accuracy. Can be made.

According to the second aspect of the invention, the lower film is formed on the outer peripheral portion of the substrate whose outer diameter is uniform over the entire length,
Since this lower film is formed in a shape in which the central portion gradually becomes thicker than both ends, and the heating resistor layer and electrodes are formed on the outer peripheral portion of this lower film, the central portion has a larger diameter than both ends. The drum-shaped roll heater can be easily formed without any trouble, and therefore the manufacturing cost can be reduced and the dimensional accuracy can be improved.

According to the third aspect of the invention, the lower film is formed on the outer peripheral portion of the substrate whose outer diameter is uniform over the entire length,
Since this lower film was formed in a shape in which both ends gradually become thicker than the central part, and the heating resistor layers and electrodes were formed on the outer peripheral part of this lower film, the central part had a smaller diameter than the both ends. It is possible to easily form the roll-shaped roll heater without any trouble, and therefore, it is possible to reduce the manufacturing cost and improve the dimensional accuracy.

According to the invention described in claim 4, since the fixing device is formed by using the roll heater according to claim 1 or 2, the fixing device can be easily formed and the manufacturing cost can be reduced. be able to.

According to the fifth aspect of the invention, since the fixing device is formed by using the roll heater according to the third aspect, the fixing device can be easily formed and the manufacturing cost can be reduced. it can.

According to the invention of claim 6, the image forming apparatus is formed by using the fixing device of claim 4 or 5, so that the image forming apparatus can be easily formed.
The manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional front view showing a roll heater according to a first embodiment of the present invention.

FIG. 2 is a vertical cross-sectional side view showing a fixing device using the roll heater.

FIG. 3 is a schematic vertical sectional view showing an image forming apparatus using the fixing device.

FIG. 4 is a vertical sectional front view showing a roll heater according to a second embodiment of the present invention.

FIG. 5 is a vertical sectional side view showing a fixing device using the roll heater.

FIG. 6 is a schematic vertical sectional view showing an image forming apparatus using the fixing device.

FIG. 7 is a vertical sectional front view showing a roll heater of a conventional example.

[Explanation of symbols]

 5,22 Roll heater 6,23 Fixing device 7,24 Image forming device 8 Substrate 9 Heating resistor layer 10a, 10b Electrode 11 Upper film 12 Pressure roller 20 Paper 21 Transfer means 25 Lower film

Claims (6)

[Claims] 1. A cylindrical or cylindrical base having electrical insulation and having a uniform outer diameter over the entire length; a heating resistor layer formed on the outer peripheral portion of the base; both ends of the base in the axial direction. An electrode formed on an outer peripheral portion of the heating resistor layer in a portion; covering a portion sandwiched by the electrode of the heating resistor layer, and gradually increasing a central portion in comparison with both axial end portions of the base. A roll heater comprising: an upper film; 2. A cylindrical or cylindrical base having electrical insulation and having a uniform outer diameter over the entire length; a base formed on the outer peripheral portion of the base as compared with both axial end portions of the base. A lower film having a gradually increasing thickness; a heating resistor layer formed on the outer peripheral portion of the lower film; electrodes formed on the outer peripheral portion of the heating resistor layer at both axial ends of the base; A roll heater comprising. 3. A cylindrical or columnar base body having electrical insulation properties and having a uniform outer diameter over the entire length; both ends of the base body formed on the outer peripheral portion of the base body as compared to the central portion in the axial direction of the base body. A lower film having a gradually increasing thickness; a heating resistor layer formed on the outer peripheral portion of the lower film; electrodes formed on the outer peripheral portion of the heating resistor layer at both axial ends of the base; A roll heater comprising. 4. A roll heater according to claim 1 or 2,
And a pressure roller which is arranged parallel to the roll heater and has an outer peripheral surface facing the outer peripheral surface of the roll heater. 5. A roll heater according to claim 3, and a pressure roller which is arranged parallel to the roll heater and whose outer peripheral surface faces the outer peripheral surface of the roll heater. And fixing device. 6. A means for forming a toner image on a photoreceptor;
6. A transfer device for transferring the toner image formed on the photosensitive member onto a sheet of paper; and a fixing device according to claim 4 for fixing the toner image transferred onto the sheet of paper onto the sheet of paper. Image forming apparatus.