JPH0245312B2 - MENHIITA - Google Patents

Description

[Detailed description of the invention]

Industrial Application Field The present invention is used as a heat source for equipment that uses electrical energy, such as space heaters, cookers, and drying equipment. This concerns a fixed surface heater. BACKGROUND OF THE INVENTION In recent years, surface heaters have come into the spotlight as heating elements that meet the demands of thinning devices and uniform heating, and various surface heaters such as those shown below have been developed. (1) Those with a structure in which a heater is wound around an insulating substrate such as mica. (2) A structure in which a conductive pattern is formed on an alumina substrate using a conductive paste such as tungsten, and then an alumina substrate is placed on top of the conductive pattern and integrally molded. (3) A device with a laminated structure in which a conductive pattern is formed between organic films such as silicon or polyimide. However, the surface heater (1) has poor heat transfer to the heated object and has problems with moisture resistance because the heater is not sealed. The reality is that since the strength is low and the heat capacity is large, the start-up time is long, and the surface heater (3) has a low heat resistance temperature and has problems with its life characteristics. Therefore, in order to solve the above problem,
A surface heater using a hollow substrate as shown in Japanese Patent No. 58-225592 has been proposed. Furthermore, the present inventors have further improved the surface heater using the hollow substrate described above, and have proposed a new surface heater using a heater element made of a smooth mesh metal foil. The surface heater proposed by the present inventors has a heater coating layer made of hollow material on a hollow substrate, and further includes a heater element made of a smooth mesh metal foil in this heater coating layer, and a heater element made of a smooth mesh metal foil body, and It had a structure in which a part of the electrical outlet terminal board connected to the element was buried. Problems to be Solved by the Invention In the surface heater having the above-described structure, the hollow film thickness of the hollow substrate forming the electrical insulating layer is
Since the heater element is very thin (150 to 200 μm), if the flatness of the heater element is poor, the end of the heater element will be buried in the hollow layer (electrical insulating layer) of the hollow substrate when the heater coating layer is fired, and as a result, the hollow There were problems such as an insulating distance from the metal part of the board not being able to be secured, and dielectric strength and insulation resistance between the metal part and the heater element decreasing, resulting in a very high defective rate. The present invention solves these problems,
To provide a surface heater in which electrical properties such as dielectric strength and insulation resistance do not deteriorate even if the flatness of a heater element is slightly poor. Means for Solving the Problems In order to solve the above problems, the present invention positions the heater element so that it is concave with respect to the hollow substrate, and covers the heater element with a heater made of hollow material. It is coated with a layer and fixed to a hollow substrate. Effect According to the above configuration, the heater element is positioned so as to be concave with respect to the hollow substrate, and the heater element is covered with a heater coating layer made of hollow material and fixed to the hollow substrate. Therefore, even if the flatness of the heater element is a little poor, the end portion of the heater element will not sink into the electrical insulating layer constituting the hollow substrate. Embodiment Hereinafter, an embodiment of the present invention will be described based on the accompanying drawings. In FIGS. 1 and 2, reference numeral 1 denotes a hollow substrate in which an electric insulating layer 1b made of hollow material is formed on both the front and back sides of a metal substrate 1a, and a concave heater element 2 is placed on top of this hollow substrate 1. , and by covering this heater element 2 with a heater coating layer 3 made of hollow material,
A heater element 2 is fixed to a hollow substrate 1. The heater element 2 is made of a smooth mesh metal foil body formed into a desired pattern, and has an electrical outlet terminal plate 2a fixed thereto by spot welding. The heater element 2 was formed in a concave shape so that the end portion 2b of the heater element 2 faced upward with respect to the hollow substrate 1. On the other hand, as a comparative example of the embodiment of the present invention, a sample in which the heater element 2 was formed in a concave shape opposite to that of the embodiment, that is, a sample in which the heater element 2 was arranged in a convex shape with respect to the hollow substrate 1 was simultaneously manufactured. In this case, the number of pieces produced was n=30 for both the example and the comparative example. The dielectric strength of the sample produced in this way was evaluated. The results are shown in the table below.

[Table] As is clear from the table above, 40% in the comparative example
However, there were no defective products in the example. Effects of the Invention As described above, according to the present invention, the heater element is positioned so as to have a concave shape with respect to the hollow substrate, and the heater element is coated with a heater coating layer made of a hollow material. Even if the flatness of the heater element is a little poor, the end of the heater element will not be wedged into the electrical insulation layer that makes up the hollow board, and as a result, the metal part of the hollow board and the heater element will be There is no reduction in dielectric strength or insulation resistance between the two, and the process of mounting the heater element on the hollow substrate is simplified, resulting in cost reduction.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part of a surface heater showing an embodiment of the present invention, and FIG. 2 shows a heater element of the same heater, in which a is a front view and b is a side view. 1...Hollow board, 1a...Metal board, 1b...
...Electric insulation layer, 2... Heater element, 3...
Heater coating layer.

Claims (1)

[Claims] 1. A surface heater characterized in that the heater element is positioned so as to have a concave shape with respect to the hollow substrate, and the heater element is covered with a coating layer made of hollow material and fixed to the hollow substrate.