JPH065356A - Line type heater body structure - Google Patents

Abstract

PURPOSE:To reduce the manufacturing cost and camber deformation in a line type heater body composed of a long and narrow shape ceramic insulating substrate and a heating resistor pattern formed so as to be extensible in the lengthwise direction to this insulating substrate. CONSTITUTION:The obverse side among both the reverse and the obverse of the insulating substrate 11 is constituted in a contact surface to a sheet material 13 to be heated, on the one hand, the heating resister pattern 15 is formed on the reverse side of the insulating substrate 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a line type heating element used for a heating section such as a toner fixing section in a copying machine or an electrophotographic printer.

[0002]

2. Description of the Related Art Heretofore, a roller type heater having a built-in heater has been used as this type of heating element. However, this roller type heating element is not only complicated in structure but also large in size. Recently, for example, as described in JP-A-2-65086 and JP-A-2-129883, and as shown in FIGS. 6 and 7, the upper surface of an insulating substrate 1 formed of ceramic into a rectangular shape. A strip-shaped heat generating resistance pattern 2 is formed so as to extend in a straight line along the longitudinal direction of the insulating substrate 1, and energizing terminal portions 3 and 4 are formed at both ends thereof, while the upper surface of the insulating substrate 1 is formed. Then, a protective film 5 made of glass is formed so as to cover the heating resistance pattern 2, and a sheet material 6 such as paper, which is an object to be heated, is brought into contact with the protective film 5 by a roller 7. It is configured to do.

[0003]

By the way, in this conventional line-type heating element, a relatively high AC voltage (for example, 100 V or 200 V) is applied to the heating resistance pattern 2.
Is applied, the glass protective film 5 covering the heating resistance pattern 2 is required to have high electric insulation.

On the other hand, since the insulation resistance of the protective film 5 is proportional to the film thickness, the film thickness of the glass protective film 5 must be made considerably thick. When the thickness is increased, bubbles are generated inside the protective film 5 when the protective film 5 is formed, and the insulation resistance is reduced. Therefore, conventionally, when the thickness of the protective film made of glass is thin, focusing on the fact that the generation of bubbles is small, forming a thin protective film made of glass, by repeating a plurality of times, Since it is formed to have a predetermined film thickness as a whole, a great deal of trouble is required to form the protective film, which causes a problem that the cost required for manufacturing the line-type heating element is significantly increased. there were.

Further, increasing the thickness of the glass protective film 5 causes a large warp deformation in the entire heating body due to the difference in the coefficient of thermal expansion between the protective film 5 and the insulating substrate 1. There was also a problem that it would occur. The present invention is
It is a technical object to provide a line-type heating body that solves the above problem by paying attention to the fact that the ceramic insulating substrate is a good conductor of heat in itself. .

[0006]

In order to achieve this technical object, the present invention provides an insulating ceramic substrate having an elongated shape and a heating resistance pattern formed so as to extend in the longitudinal direction with respect to the insulating substrate. The front surface side of the front and back surfaces of the insulating substrate is configured to be a contact surface for the sheet material to be heated, and the heating resistance pattern is formed on the back surface side of the insulating substrate.

[0007]

[Operation] With this configuration, the heat generated in the heating resistance pattern formed on the back surface side of the insulating substrate is transferred to the front surface side of the insulating substrate. The sheet material can be heated. That is, the heated sheet material contacting the front surface side of the insulating substrate is heated by the heating resistance pattern formed on the back surface side of the insulating substrate, wherein the insulating substrate is
Since it serves as a protective film for the heating resistance pattern formed on the back surface side, high electrical insulation can be secured for the heating resistance pattern.

[0008]

Therefore, according to the present invention, it is possible to omit forming a protective film having a large film thickness and a high insulation resistance on the heating resistance pattern as in the conventional case. This has an effect that the manufacturing cost of the die heating element can be significantly reduced, and the warp deformation of the entire heating element can be significantly reduced.

[0009]

Embodiments of the present invention will now be described with reference to the drawings. 1 to 3 show a first embodiment, in which reference numeral 11 denotes an elongated ceramic insulating substrate, and a thin glass film 12 is formed on the upper surface of the insulating substrate 11. Then, the sheet material 13, which is an object to be heated, is brought into contact with the surface of the thin glass film 12 by pressing the roller 14.

On the other hand, a strip-shaped heat generating resistance pattern 15 is formed on the lower surface of the insulating substrate 11 so as to extend in a substantially straight line along the longitudinal direction of the insulating substrate 11, and energizing terminals for both ends of the heat generating resistance pattern 15 are formed. 16 and 17 are formed. Reference numeral 18 is a support member for supporting the insulating substrate 11, and the support member 18 is made of heat-resistant synthetic resin. Further, a thin protective film may be formed on the heating resistance pattern 15.

When a current is applied to the heat generating resistance pattern 11 from the current-carrying terminals 16 and 17 at both ends of the heat generating resistance pattern 11, the heat generating resistance pattern 11 generates heat, and the heat passes through the insulating substrate 11 to cause the heat in the insulating substrate 11. Since the heat is transferred to the upper surface side, it is possible to heat the heated sheet material 13 in contact with the glass film 12 on the upper surface side of the insulating substrate 11.

In the above embodiment, the thin glass film 12 is formed on the upper surface of the insulating substrate 11 to smooth the upper surface. However, the upper surface of the insulating substrate 11 is smoothed by polishing or the like. When the surface is finished, the glass film 12 can be omitted. FIG. 4 and FIG. 5 show a second embodiment. This embodiment is applied to the case where the glass film 12 is formed on the upper surface of the insulating substrate 11 in order to make the upper surface smooth. Before forming the glass film 12, a high temperature coefficient resistor pattern 19 as a temperature detecting element such as a thermistor is formed on the upper surface of the insulating substrate 11, and then the glass film 12 is formed on the high temperature coefficient resistor pattern. It is formed so as to cover 19.

With this structure, the high temperature coefficient resistor pattern 19 has the same temperature as the heating temperature for the heated sheet material 13. Therefore, the accuracy in controlling the heating temperature can be surely improved. Can be done. Since the control power supply applied to the high temperature coefficient resistor pattern 19 is normally about 5 V in direct current, the electric insulation of the glass film 12 covering the high temperature coefficient resistor pattern 19 does not matter. Absent.

[Brief description of drawings]

FIG. 1 is a plan view of a heating body according to a first embodiment of the present invention.

FIG. 2 is a bottom view of the heating body according to the first embodiment of the present invention.

FIG. 3 is an enlarged sectional view taken along line III-III in FIG.

FIG. 4 is a plan view of a heating body according to a second embodiment of the present invention.

5 is an enlarged sectional view taken along line VV of FIG.

FIG. 6 is a plan view of a conventional heating body.

FIG. 7 is an enlarged sectional view taken along line VII-VII of FIG.

[Explanation of symbols]

 11 Insulating Substrate 12 Glass Film 13 Heated Sheet Material 14 Roller 15 Heating Resistance Pattern 16, 17 Conductive Terminal

Claims (1)

[Claims] 1. An elongated ceramic insulating substrate and a heating resistance pattern formed on the insulating substrate so as to extend in the longitudinal direction thereof. A structure of a line type heating element, characterized in that the heating resistance pattern is formed on the back surface side of the insulating substrate while constituting the contact surface with the heating sheet material.