JPS631430Y2 - - Google Patents

Description

[Detailed description of the invention] (Technical field) This invention relates to a planar heating element.

(Background Art) A conventional planar heating element used in electric carpets, etc. is a heat-sensitive film 11 as shown in FIG.
A heat-generating electrode 12 and a heat-sensitive electrode 13 are provided on one surface, a reflective electrode 14 is provided on the other surface, and these are covered with an insulating film 15 such as polyethylene film or polyester film. Such a planar heating element changes the temperature resistance value of the heat-sensitive film 11 through the reflective electrode 14 between the heat-generating electrode 12 and the heat-sensitive electrode 13, as shown in FIG. The resistance value of the part |Z _H |
The resistance value of the opposing portions of the heat-sensitive electrode 13 and the reflective electrode 14 is the sum of |Z _S | = _{| Z H |} + | Z _S |
This is used to detect and control temperature.

On the other hand, in manufacturing a sheet heating element, 2
A heat-sensitive film 11 is sandwiched between two metal foils, and a predetermined shape is printed on the surface of each metal foil using resist ink, and then an etching process is performed to form a predetermined electric circuit such as the heating electrode 12. A common process is to cover the insulating film 15 with an insulating film 15.

However, in the printing process, the thermal film 11
Printing misalignment occurs between the metal foils on the front and back sides of the
There is a problem in that the relative positional relationship of the reflective electrode 14 with respect to 3) is shifted, resulting in large variations in the electrical characteristics |Z _T | of the heating element. This printing misalignment occurs in both the flow direction (direction a in FIG. 3) and the width direction (direction b in FIG. 3) during the manufacturing process of the planar heating element.

For example, in FIG. 3B, if only the reflective electrode 4 is misaligned in the right direction, the opposing area of the heating electrode 12 and the reflective electrode 14 decreases, resulting in an increase in total impedance. In order to eliminate this problem, the size of the reflective electrodes 14 should be made large so that the facing area does not change even if printing misalignment occurs, but the length of the gap between each heating electrode 12 must be There is a limit to
Since there may be cases where the reflective electrode 14 should not be opposed to the adjacent heating electrode 12, the reflective electrode 1
The reality is that 4 cannot be made larger than a certain value.

In the past, as shown in FIG. 3A and C, between the reflective electrodes 14 and the heating electrode 12
Or the parts c, d facing the heat-sensitive electrode 13
There is also a drawback that stepping on this part causes stress concentration, which causes cracks in the heating electrode 12 and the like, leading to wire breakage.

(Purpose of the invention) The present invention was proposed to solve the above-mentioned drawbacks, and its purpose is to create a structure that does not substantially affect the total impedance of the thermal film even if printing misalignment occurs on the front and back sides of the thermal film. By doing so, it is an object of the present invention to provide a planar heating element which enables accurate temperature control and prevents accidents such as circuit breakage due to external force.

(Disclosure of invention) The present invention will be explained below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. In the figure, 1 is a heating electrode formed in a zigzag shape on the surface of a heat-sensitive film 2, and a heat-sensitive electrode 3 is arranged in parallel with this heating electrode 1. ing. On the other hand, a reflective electrode 4 is formed on the back surface of the heat-sensitive film 2 so as to face both the heat-generating electrode 1 and the heat-sensitive electrode 3.
In the present invention, the maximum printing deviation W (for example, 1
mm) and in the flow direction (direction a in FIG. 1) by the maximum dimension X (for example, 2 mm) of the printing deviation. In addition, in Figure 1, 5
indicates an insulating film.

As a result, if the reflective electrode 4 is misaligned to the right in FIG. 1B, for example,
The opposing area between the left heating electrode 1 and the reflective electrode 4 decreases, but the same area increases in the opposing area between the right heating electrode 1 and the reflective electrode 4, so the total impedance |Z _T | There is no change and there is no risk of interfering with temperature control.

Fig. 2 shows another embodiment of the present invention, in which the reflective electrode 4' is made as small as possible, with the overlapped part with the heat-sensitive electrode 3 in the flow direction being X+1 mm, and the overlapped part with the heat-generating electrode 1 in the width direction. is configured so that W+1mm.

(Effects of the invention) As described above, according to the invention, a heat-generating electrode and a heat-sensitive electrode are arranged side by side on one side of a heat-sensitive film, and
In the planar heating element comprising a reflective electrode facing the heat generating electrode and the heat sensitive electrode on the other surface of the heat sensitive film, the reflective electrode is placed inside the heat generating electrode and the heat sensitive electrode when viewed from a plane. Even if printing misalignment occurs, the position of the reflective electrode with respect to the heating electrode and heat-sensitive electrode will not substantially shift due to the small reflective electrode formed in advance, so the total impedance of the heat-sensitive film can be reduced. There are no changes or variations in temperature, and the effect is that accurate temperature control and maintenance of the set temperature are possible.

In addition, parts e and f in FIG. Since there is a part f where the heat-sensitive electrode protrudes from the outer periphery of the reflective electrode, stress concentration due to stepping on the electrode is unlikely to occur, and there is no risk of accidents such as wire breakage.

Furthermore, as the charging area becomes smaller, the impedance becomes higher, and as a result, the control current flowing between the heat-generating electrode and the heat-sensitive electrode decreases. This has advantages such as the ability to reduce the size of the inside of the controller, and reduce the amount of heat generated inside the controller to reduce losses.

[Brief explanation of drawings]

Figure 1 shows one embodiment of the present invention.
Figure A is a plan view of the main part, Figure B is a C-C sectional view of the same Figure,
Fig. 2 is a plan view of the main part showing another embodiment, Fig. 3 is a conventional example, Fig. 3A is a plan view of the main part, Fig. 1 is a BB sectional view of A, and d is an equivalent sectional view. 1... Heat generating electrode, 2... Heat sensitive film, 3...
Heat-sensitive electrode, 4,4'...Reflecting electrode.

Claims (1)

[Scope of utility model registration request] In a planar heating element comprising a heat-generating electrode and a heat-sensitive electrode arranged side by side on one side of a heat-sensitive film, and a reflective electrode facing the heat-generating electrode and the heat-sensitive electrode on the other side of the heat-sensitive film, the reflective electrode is
A planar heating element characterized in that the reflective electrode is formed small so as to be disposed inside the heating electrode and the heat-sensitive electrode when viewed from above.