JPS6240548Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a planar heating element in which a heater circuit formed by patterning metal foil is mounted on an enamel substrate.

1 and 2 show a conventional example of a planar heating element using an enamel substrate formed by firing an enamel layer 1b on a metal core 1a.
A thick film paste with high resistance (e.g. Pd
-Ag-based paste) is printed and fired to create a structure in which the heater circuit 2 is mounted.

However, in the heater circuit 2 in these conventional examples, by firing a thick film paste,
The conductor fine powder in the thick film paste becomes electrically connected to each other, but the resistance value tends to vary depending on the firing conditions, and the resistance value may change due to oxidation etc. during the use period. There were problems such as the tendency for changes to occur.

The present invention was developed based on these backgrounds, and by mounting a patterned metal strip made of a base metal material in place of a thick film paste containing a noble metal material as an active ingredient, it is possible to reduce material costs and reduce material costs. The purpose is to improve mass productivity, to prevent variations in resistance value by utilizing the uniformity of the material inherent in metal materials, and to prevent changes in resistance value over time. It is something.

The present invention will be described below based on embodiments shown in the drawings.

FIGS. 3 and 4 show an embodiment of the present invention, and the planar heating element of this embodiment is formed on a first enamel enamel layer 3 covering a metal core 1a of an enamel substrate 1A. , a second enamel layer 4 integrated with the first enamel layer.
It has a structure in which a patterned metal wire body 5 coated with is placed.

The first and second enamel layers 3 and 4
are made of crystallized enamel enamel or amorphous enamel made from glass frit as described in JP-A-56-73643, for example, and the first enamel enamel layer 3 is made of the second enamel enamel. The ingredients are blended so that the softening point and melting point are higher than those of the enamel layer 4.

The patterned metal wire body 5 is formed by cutting or bending base metal foil, plate, wire, etc. of base metal (for example, metals with high electrical resistance such as iron, nickel, chromium, or alloys thereof) to form a heater circuit. It is designed to fit the shape.

When manufacturing a planar heating element having such a structure, first and second enamel layers 3 and 4 are applied to the surfaces of the metal core 1a and the patterned metal filament 5, respectively, and fired. Then,
As shown in FIG. 3, by firing the patterned metal wire bodies 5 on the enamel substrate 1A, a planar heating element as shown in FIG. 4 can be obtained.

In the firing step, firing is performed at a temperature higher than the melting point of the second enamel enamel layer 4 covering the patterned metal filament 5 and lower than the softening point of the first enamel enamel layer 3 of the enamel substrate 1A. It is necessary to control the temperature, and by performing firing under such temperature conditions, only the second enamel enamel layer 4 is melted and the first enamel enamel layer 3 is melted, as shown in FIG. Can be fixed. Further, in the firing step, the second
Since the second enamel enamel layer 4 melts into a fluid state, the patterned metal The filamentous body 5 approaches the metal core 1a. however,
Under the above-mentioned temperature conditions, the first enamel enamel layer 3 remains solid, so that the first enamel enamel layer can provide insulation between the patterned metal filament 5 and the metal core 1a.

Note that the first and second enamel layers 3 and 4
The temperature difference in the softening point (or melting point) of is determined by the control accuracy of the firing temperature, for example,
It is preferable to set the temperature difference to 50℃ or more.

Next, FIG. 5 shows another embodiment of the present invention, in which the melting point of the first enamel layer 3A is set higher than the softening point of the second enamel layer 4A.

In the planar heating element of this embodiment, as shown in FIG. 5, only the first enamel layer 3A is in a molten state.
The patterned metal filament 5A coated with the second enamel layer 4A is submerged in the enamel layer, and both the enamel layers 3A and 4A are fixed together.

As is clear from the above description, the present invention covers a metal core and a patterned metal filament formed of a base metal material with first and second enamel layers, respectively, and coats both enamel enamel layers. It is characterized in that the melting point and softening point of one of these layers is set lower than that of the other enamel layer, and has the following effects.

Since the patterned metal filament can be easily manufactured by subjecting a common base metal material to simple processing such as punching and bending, it is possible to reduce the cost of the planar heating element.

Since the metal material forming the patterned metal wire body is essentially a uniform material, there is little variation in resistance value.

Since the surface of the patterned metal filament is covered with an enameled enamel layer, there are few changes over time such as oxidation and corrosion, and it can exhibit stable performance over a long period of time.

[Brief explanation of the drawing]

1 and 2 show a conventional example of a sheet heating element, in which FIG. 1 is a plan view, FIG. 2 is a sectional view taken along the line - in FIG. 1, and FIGS. Figure 4 shows one embodiment of the present invention, Figure 3 is a cross-sectional view showing the state before firing, Figure 4 is a cross-sectional view showing the state after firing, and Figure 5 is another embodiment of the present invention. It is a sectional view showing an example. 1A... Enamel substrate, 1a... Metal core, 3
...First enamel enamel layer, 3A...First enamel enamel layer, 4...Second enamel enamel layer, 4A...Second enamel enamel layer, 5
...Patterned metal filament, 6...Glass frit.

Claims (1)

[Scope of utility model registration request] An enamel substrate 1A formed by coating the surface of a metal core 1a with first enamel enamel layers 3, 3A;
It consists of a first enamel enamel layer of the enamel substrate and a patterned metal strip 5 coated with an integral second enamel enamel layer 4, 4A, one of said enamel enamel layers being one of the enamel enamel layers of the other. A planar heating element characterized by being made of a material having a lower softening point and melting point than the layer.