JPS6319066B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application) The present invention relates to a planar heating element having upper and lower layers of thin insulating films made of nylon, polyethylene, etc., with heating wires formed therebetween by etching.

(Problems with the Prior Art) In this kind of sheet heating element, a temperature detection wire for controlling the temperature of the heating wire is embedded separately from the heating wire using the same processing method as the heating wire.

Therefore, as a conventional example, there are two types in terms of the relationship between the insulating film, the heat generating line, and the temperature detecting line.

That is, one method is to attach metal foils, such as aluminum, to the upper and lower surfaces of an insulating film, and use etching to make one side a heating wire and the other side a temperature detection wire, and change the impedance of the film in between. We are trying to control the temperature through changes.

In the above case, two metal foils are required, which results in two-sided etching, and furthermore, three sheets of upper and lower films are required in addition to the above-mentioned insulating film. Of course, if a metal foil for preventing electric shock is added, which detects a short circuit with the heating wire when a pin or the like pierces the film, a fourth film will be required.

Therefore, the number of parts is large and it is not suitable for mass production.

Another method is to have a heat generating line that also serves as a temperature detecting line.

Although this requires only one metal foil and upper and lower films, and the number of components is small, it has the following problems.

In other words, for heat generation, a frequency of 50 or 60 cycles is used for the commercial power supply, and a frequency other than this cycle (generally 1000 cycles) is passed through the heat generation line and the current value is monitored as the temperature rises. do.
Therefore, in this dual-purpose device, two different frequencies must be used, and the reason for making the difference particularly large is to prevent malfunctions due to noise.

Further, according to experiments, when temperature control and excessive rise prevention are performed by detecting only changes in the resistance value of the metal foil, a proportional relationship is usually established between the resistance value R of the metal foil and the temperature t. This is shown in Figure 5, Rt=Ro {1+α(t-to)} α: Temperature resistance coefficient, which is 4× for ordinary metals.
10 ^-3 /℃.

For example, as shown in Figure 6, if we assume {control temperature 50℃, room temperature 20℃, temperature outside the insulation part 36℃, local insulation area 1/10 (1/10 of the total area of the surface heating element)}, the temperature in the insulation part will increase. When calculating the value, the temperature resistance coefficient of metal foil is 4 × 10 ^-3 /℃, so the resistance value R ₅₀ at 50℃ is R ₅₀ = R ₂₀ {1 + 4 × 10 ^-3 (50−20 )} = 1.123R ₂₀ . The control circuit operates with a resistance value of R ₅₀ and turns off the power.

Calculating the temperature of the insulation part when the overall resistance value calculated considering the area of the insulation part becomes equal to the control resistance value (R ₅₀ ) Assuming that this surface heating element is used for floor heating, etc., it will be controlled at a maximum temperature of 50℃ under normal usage conditions, but if 1/10 of the surface heating element is locally insulated, the temperature of the insulated part will increase to 183.5℃. There is a risk of burns or fire. Usual metals (Cu, Al,
(Fe, nichrome, etc.), the temperature resistance coefficient is about 0.4 to 0.5×10 ^-3 /°C, and a temperature rise cannot be avoided when local insulation is applied.

(Purpose) The present invention has been made in view of the above points, and
That is, after forming a heat generating line and a temperature detecting line using the same metal foil on the same side of an insulating film by etching, a semiconductor paint whose electrical resistance value changes at a temperature above a certain level is applied, and the change is detected. The purpose is to detect electrically, and the metal foil is extremely thin, measuring 10 to 50μ, so it solves the problem that detecting electrical changes between the etched sides is unreliable. It is.

(Example) The present invention will be explained below based on drawings showing an example of the present invention. FIG. 3, and a semiconductor paint 5 is partially applied between both lines 2 and 3.

Figure 2 shows the first manufacturing method. In (a), an insulating film 1 made of nylon, polyethylene, etc. is used as the lower layer, and a thin metal foil X of 10 to 50 μm made of Al, Cu, etc. is placed on the entire surface of the film. Paste it over the entire length. Next, as shown in (b), the conductive ink 4 is printed separately with insulating spaces for heat generation and temperature detection.
Incidentally, this ink 4 uses, for example, Dotite SH-1A (epoxy liquid type) manufactured by Fujikura Kasei Co., Ltd., and has a specific resistance value of 10 ^-4 Ω-cm. As shown in (c), the portions excluding the ink 4 are removed by etching to form the heat generating line 2 and the temperature detecting line 3. This etching process is performed using, for example, ferric chloride. Next, as shown in (d), the semiconductor paint 5 whose electrical resistance value changes above a certain temperature is connected to the heat generating wire 2.
Edged side surface 2 with and temperature detection wire 3
a, 3a and the upper surface of the conductive ink 4. In the final step (e), the upper insulating film 6 is coated and bonded.

A and B shown in this (e) are current paths between the heat generation wire 2 and the temperature detection wire 3, and A is the etched side surfaces 2a and 3a, which are thin but wide per unit area and are ink-filled. A bypass of B can also be detected via 4.

Next, FIG. 3 shows another manufacturing method, in which (a) metal foil X is pasted on the lower film 1, and as shown in (b), a heat generating circuit and a temperature detection circuit are printed with insulating ink 7. . This ink 7 is made of vinyl chloride. Next, perform the etching process (c). After this etching, this ink 7 is removed. The process is carried out with chemical changes, for example in caustic soda solution or in a solvent. This is shown in (d). Furthermore, a semiconductor paint 5 shown in (e) is applied. (F) shows the adhesion of a similar upper layer film 6.

(Effects) As described above, the present invention forms the heat generating line 2 and the temperature detecting line 3 on the same surface of the insulating film 1 separately from the same metal foil. It requires fewer metal foils and insulating films than the previous method, and it purposely sets different frequencies for temperature detection, as if the same wire were used for both heat generation and temperature detection. Not at all.

Furthermore, in the present invention, the semiconductor paint 5 is applied to the etched side surfaces 2a, 3a and the upper surfaces of both the wires 2, 3 so that electrical changes can be detected from both the passages A, B. The metal foil X is especially 10~
Even if it is as thin as 50μ, it can be detected from the top surface of the bypass, which has the effect of accurately detecting electrical changes.

[Brief explanation of the drawing]

The drawings show an embodiment of the method for manufacturing the sheet heating element of the present invention, with FIG. 1 being a front view, and FIG. 2 being a manufacturing process diagram.
FIG. 3 shows a different embodiment, FIGS. 4 and 5 are resistance characteristic diagrams of the metal foil, and FIG. 6 is a temperature distribution diagram. DESCRIPTION OF SYMBOLS 1...One side film, 2...Heating line, 3...Temperature detection line, 4...Ink, 5...Semiconductor paint, 6...Other film, X...Metal foil.

Claims (1)

[Claims] 1. A metal foil is attached to the upper surface of the lower layer insulating film,
On the top surface of this metal foil, conductive ink is printed to separate the heating wire circuit and the temperature detection wire circuit with an insulating space between them, and the metal foil is etched to separate the heating wire circuit and the temperature detection wire circuit. form a temperature detection wire,
Further, a semiconductor paint whose electrical resistance value changes above a certain temperature is applied to the etched side surfaces of the heating wire and temperature detection wire and the top surface of the conductive ink, and then an upper insulating layer is applied to the top surface of the semiconductor paint. A method for manufacturing a planar heating element characterized by coating and adhering a film. 2 Paste metal foil on the top surface of the lower layer insulating film,
On the top surface of this metal foil, a heat generating line circuit and a temperature detection circuit are printed separately with an insulating space using insulating ink, and this metal foil is etched to connect the heat generating line and the temperature detecting circuit. After forming a detection wire, the insulating ink is removed by a chemical method, and a semiconductor paint whose electrical resistance value changes above a certain temperature is applied to the heating wire and the temperature detection wire. A method for manufacturing a planar heating element, characterized in that the insulating ink is coated on the side surface and the top surface from which the insulating ink has been removed, and then an upper insulating film is coated and adhered to the top surface of the semiconductor coating.