JPH0426196B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a heat-sensitive sheet heating element used in electric carpets and the like.

(Background Art) Conventionally, this type of heat-sensitive sheet heating element has a heat-sensitive film 21 with a heat-generating line 22, which can also be used as a heat-sensitive line, and a second reflective electrode 23 on one surface of the heat-sensitive film 21, as shown in FIG.
A heat-sensitive wire 24 that can also be used as a heat-generating wire is provided, and a first reflective electrode 25 and a third reflective electrode 26 are provided on the other side, and an insulating film 27 such as a polyethylene film or a polyester film is provided on the front and back sides of these electrodes. 28. Such a heat-sensitive sheet heating element absorbs the change in resistance value due to the temperature change of the heat-sensitive film 21 through the heat-generating wire 22.
and _the heat-sensitive wire 24 via the first to third reflective electrodes 25, 23, 26, the sum of the resistance values of the _opposing portions of each electrode |Z| Z ₃ | + | Z ₄ | is detected and temperature control is performed.

Here, in the resistance value measurement path, the heating wire 22
The reason why the heat-sensitive film 21 is passed multiple times between the heat-sensitive wire 24 and the heat-sensitive wire 24 is that when the potential difference between both sides of the heat-sensitive film 21 becomes large, the temperature-resistance value change characteristic of the heat-sensitive film 21 changes and the temperature detection ability decreases. This is because it is necessary to divide the potential between the heat-generating wire 22 and the heat-sensitive wire 24 into four.

However, in this planar heating element, as described above, the resistance value of the heat-sensitive film 21 is the resistance value of each part |Z ₁ |~|
Since the sum of Z ₄ | becomes extremely large, the detected electrical signal becomes extremely small, and the number of electronic components required to amplify the signal increases, leading to increased costs and controller malfunction. There was a problem.

In addition, as another conventional example, as shown in FIG. 6, there is one in which only a heat generating line 29 and a heat sensitive line 30 are provided on one side of the heat sensitive film 21, and a reflective electrode 31 is provided on the other side. Same pitch as the figure d
A heat-generating line 29 and a heat-sensitive line 30 having a relatively wide line width are disposed within the line. Therefore, when designing a heat-generating/heat-sensitive circuit, in order to obtain the same resistance value (heat generation amount) under the same line length in the examples shown in Figures 5 and 6, the line width must be greater than that in Figure 6. In the narrow case of FIG. 5, it was necessary to make the thickness t ₁ of the heating wire 22, etc. thicker than the thickness t ₂ of FIG. 6 in order to equalize the cross-sectional area.

Therefore, when the heating wire 22 and the like are formed by etching metal foil, there is a drawback that the etching speed decreases and the cost increases.

Furthermore, in the example of FIG. 5, if the thickness of the metal foil on the first and third reflective electrodes 25 and 28 is made thinner, for example, t ₂ in FIG. 6, the difference between t ₁ and t ₂ will be Due to the difference in strength between the front and back sides of the heat-sensitive film 21, wrinkles tend to form in the metal foil on the thinner side when the metal foil and the heat-sensitive film 21 are bonded together. This caused the problem of disconnection.

(Objective of the Invention) The present invention has been proposed in view of the above points, and its purpose is to reduce the total resistance value by shortening the measurement path of the resistance value of the heat-sensitive film, and to reduce the number of parts. In addition to preventing malfunctions of the heat-sensitive film and controller, the same resistance value can be achieved by reducing the thickness of the metal foil on the heating wire side, increasing the etching speed and reducing costs. It is an object of the present invention to provide a heat-sensitive sheet heating element in which the thickness of metal foil constituting heating wires, reflective electrodes, etc. is made the same to prevent the occurrence of wrinkles during manufacturing.

(Disclosure of the Invention) The present invention will be described below with reference to the drawings. First, FIGS. 1 and 2 show a first embodiment of the present invention. In FIG. 1, a heat-generating wire 2 that can also be used as a heat-sensitive wire is provided on one surface of a heat-sensitive film 1. Near the line 2, as shown in FIG. 2, a plurality of divided first reflective electrodes 3 are arranged in parallel. On the other hand, on the other side of the thermosensitive film 1, there is a second reflective electrode 4 facing both the heating wire 2 and the first reflective electrode 3, and a second reflective electrode 4 facing the first reflective electrode 3.
A heat-sensitive wire 5 that can also be used as a heat-generating wire is provided. Note that the second reflective electrode 4 is also divided into a plurality of parts as shown in FIG. Furthermore,
Insulating films 6 and 7 made of polyethylene film or the like are pasted on the front and back sides of these.

In this embodiment, in order to switch the wattage, when the heating wire 2 is energized and used, the heating wire 5 is switched on.
However, when a heat-sensitive wire 5 having a different resistance value is used as a heat-generating wire, the heat-generating wire 2 is made to function as a heat-sensitive wire. Note that the thickness t ₃ of the metal foil forming the heating wire 2 and the first reflective electrode 3 is the same as the thickness t ₃ ' of the metal foil forming the second reflective electrode 4 and the heat-sensitive wire 5. It is desirable that the heating wire 2
It goes without saying that by changing the thickness of the wire 5 and the heat-sensitive wire 5 to change the resistance value, the amount of heat generated can be changed during switching use.

Therefore, in the present invention, the sum of the resistance values of each part between the heat generating wire 2 and the heat sensitive wire 5 via the second and first reflective electrodes 4 and 3 is |Z|=|Z ₁ |+|Z ₂ |+|Z ₃ | is used to detect a change in the resistance value of the heat-sensitive film 1, and thereby perform temperature control. Also,
In the present invention, since only the heating wire 2 and the first reflective electrode 3 or the second reflective electrode 4 and the heat-sensitive wire 5 are arranged in the pitch d, the width of each line can be widened, and the metal The thicknesses t ₃ and t ₃ ' of the foil can be made thinner than conventional ones.

Next, in an electric carpet or the like using this planar heating element, a case where a conductive member such as a pin comes into contact with a heating wire or the like and electricity cannot be supplied will be considered. First, in FIG. 2, when the pin is inserted into positions a, b, and c, the heating wire 2 and the heat-sensitive wire 5 are short-circuited, so that electricity cannot be supplied. When inserted at positions a, c, e, etc., there is no risk of short-circuiting between the heating wire 2 and the heat-sensitive wire 5, and electricity can be applied. Therefore, the occurrence of accidents due to short circuits caused by pins, etc. is extremely rare, and a highly reliable electric carpet can be obtained.

Next, FIG. 3 shows a second embodiment of the present invention. In this embodiment, the first reflective electrode 3' is arranged in parallel with the heating line 2 without being divided, and only the second reflective electrode 4 is connected. It is formed by dividing. According to this example, in addition to obtaining the same effect as the first embodiment described above, when a pin is inserted into positions a, b, and e, for example, the heating wire 2 and the heat-sensitive wire 5 are short-circuited.
When the pins are inserted into positions a, c, e, etc. other than these, electricity can be supplied without shorting, so it is possible to provide an electric carpet that has considerable reliability, although it is inferior to the first embodiment.

Note that as an application example of this embodiment, although not shown, the first reflective electrode is divided, while the second reflective electrode is divided into two parts.
It is also possible to adopt a structure in which the reflective electrode 4 is arranged in parallel to the heat-sensitive wire 5 without being divided. In any case, if the continuously formed reflective electrode can also be used as a heating wire, the original heating wire 2, heat-sensitive wire 5, and reflective electrode can be mutually connected to each other. It is possible to form a planar heating element that can have both functions and switch the amount of heat generated at various stages.

Furthermore, FIG. 4 shows a third embodiment of the present invention. In this embodiment, both the first reflective electrode 3' and the second reflective electrode 4' are arranged in parallel with the heating line 2 and the heat-sensitive line 5, respectively, without being divided. In this embodiment as well, it is possible to obtain the same effects as in the first embodiment, such as a reduction in the resistance value of the heat-sensitive film 1 and a reduction in the line width of the metal foil.

In each of the embodiments shown in FIGS. 1 to 4, the probability that electricity cannot be supplied due to a short circuit between the heating wire 2 and the heat-sensitive wire 5 due to a pin or the like is, for example, 1 in the case of an electric carpet with a 2-tatami specification. /4000:1/
It will be about 200:1. In addition, considering this ratio and the possibility of a short circuit due to the introduction of conductive foreign matter into the heat-sensitive film 1 during the manufacturing stage of the planar heating element, it is possible to Just like that,
Preferably, at least one of the first and second reflective electrodes is divided into a plurality of parts.

Furthermore, in these embodiments, the voltage between the electrodes between the heating wire 2 and the heat-sensitive wire 5 is divided into three parts, so that the potential of each part increases slightly compared to the conventional example shown in FIG. Compared to the conventional example shown in FIG. 6, which is divided into two parts, the potential of each part is lowered, and the change in temperature characteristics is practically small.

(Effects of the Invention) As described above, according to the present invention, a first reflective electrode and a heating wire that can also be used as a heat-sensitive wire are provided on one surface of the heat-sensitive film, and the first reflective electrode is provided on the other surface of the heat-sensitive film. Since a second reflective electrode facing both the reflective electrode and the heating wire is provided, and a heat-sensitive wire that faces the first reflective electrode and can also be used as a heating wire, it is easy to control the temperature. Since the measurement path for low resistance values becomes shorter and the total resistance value decreases,
It is possible to reduce the number of electronic components required for amplifying the detected electrical signal, etc., thereby reducing costs and preventing malfunction of the controller.

In addition, by forming wide-width heating lines, heat-sensitive lines, etc. within the same two-dimensional pitch, the thickness of the metal foil can be reduced, which shortens manufacturing time by increasing the etching speed and reduces the amount of material used. Therefore, it is possible to reduce costs. Furthermore, by using metal foils of equal thickness on the front and back sides of the heat-sensitive film, there is no risk of wrinkles occurring when the heat-sensitive film and metal foil are pasted together, and breakage of the heating wire or heat-sensitive wire is prevented. It is possible to do so.

In addition, since the heat-generating wire and the heat-sensitive wire are reversible, there are various effects such as easy switching of the amount of heat generated.

[Brief explanation of drawings]

1 and 2 show a first embodiment of the present invention, FIG. 1 is a partial cross-sectional view, FIG. 2 is a partial plan view, and FIG. 3 is a portion showing a second embodiment of the present invention. FIG. 4 is a partial plan view showing a third embodiment of the present invention, and FIGS. 5 and 6 are partial cross-sectional views showing a conventional example. 1...Thermal film, 2...Heating wire, 3, 3'
...First reflective electrode, 4, 4'... Second reflective electrode, 5... Heat sensitive wire, 6, 7... Insulating film.

Claims (1)

[Claims] 1. A first reflective electrode and a heating wire that can also be used as a heat-sensitive wire are provided on one surface of a heat-sensitive film, and both the first reflective electrode and the heating wire are provided on the other surface of the heat-sensitive film. A heat-sensitive sheet heating element, comprising: a second reflective electrode facing the first reflective electrode; and a heat-sensitive wire that faces the first reflective electrode and can also be used as a heat-generating wire. 2. The heat-sensitive sheet heating element according to claim 1, wherein at least one of the first and second reflective electrodes is divided into a plurality of parts.