JP2694882B2 - Planar heating element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

2. Description of the Related Art Generally, a sheet heating element of this type is provided with a flexible cloth-like woven heating sheet in which fibrous heating wires are woven. As the overheat preventing means for the woven heat generating sheet, as a sensor for temperature control, a heat sensitive wire is connected to the temperature controlling means, and based on the temperature of the heat generating sheet detected by this heat sensitive wire, the temperature of the heat generating sheet. Is being adjusted.

[0002]

In the sheet heating element having the above structure, if the temperature control means fails for some reason,
Since there is no means to visually check that abnormal overheating has occurred, the user may continue to use the planar heating element without noticing the failure of the temperature control means.In the worst case, scorching or the like may occur. , There was a problem that caused a fire.

The sheet heating element according to the first aspect of the present invention has been made in view of the above problems, and provides a sheet heating element having a simple structure that allows visual inspection when abnormal overheating occurs. To do. Further, in addition to the above object, the sheet heating element according to the second aspect of the present invention is intended to provide a sheet heating element that can more surely prevent burning and fire due to abnormal overheating.

[0004]

In order to solve the above-mentioned problems, the sheet heating element according to the present invention comprises a temperature sensor,
A planar heating element including a heat generating sheet (1) and temperature control means for adjusting the temperature of the heat generating sheet (1) based on the temperature of the heat generating sheet (1) detected by the temperature sensor is flexible. A heat-shrinkable resin film or resin sheet that shrinks visibly at a predetermined temperature, which causes abnormal overheating exceeding the temperature adjusted by the temperature control means, on at least one surface of the heat-generating sheet (1) 6 having heat-shrinkability. It is characterized by being laminated. Further claim 2
In addition to the configuration of the sheet heating element according to claim 1, the sheet heating element according to claim 1 is provided with the heat shrinkable resin film or resin sheet over the entire surface of the sheet heating sheet (1) and the sheet heating sheet (1).
Laminated between the sheet-like protective electrode (2a) for covering ,
It is an insulating layer (2b) made of polypropylene.

[0005]

In the sheet heating element according to the first aspect of the present invention having the above structure, when the sheet is overheated, for example, at 130 ° C. to 190 ° C., the sheet heating element shrinks due to heat. It is possible to visually observe that wrinkles have occurred on the whole and abnormal heating has occurred in the sheet heating element.

Further, in the sheet heating element according to the second aspect of the present invention, when abnormal overheating occurs, the insulating layer shrinks to form a portion where a short circuit is likely to occur locally, so that the heat of the heating sheet is melted by the melting point of the insulating layer. When the temperature reaches, the above-mentioned portion is surely melted, and the protective electrode and the heat sheet can be surely short-circuited.

[0007]

The sheet heating element of the present invention will be described below with reference to the drawings showing examples. As shown in FIG. 1, a planar heating element A according to an embodiment of the present invention comprises a woven heat generating sheet 1 as a flexible heat generating sheet, and a protective electrode sheet laminated on the upper surface of the woven heat generating sheet 1. 2, a back material 3 laminated on the upper surface of the protective electrode sheet 2, and a back material 4 laminated on the lower surface of the woven heat generating sheet 1. Ma
In addition, the on-plane heating element A of the present invention is the same as the conventional one.
A heat-sensitive wire that serves as a temperature sensor that measures the temperature of the heat-generating sheet 1.
And the temperature of the heat generating sheet 1 detected by this heat sensitive wire
A temperature control hand for adjusting the temperature of the heat generating sheet 1 based on
Equipped with steps.

As shown in FIG. 2, the woven heat generating sheet 1 has a first yarn group 11 including a heat generating wire 11a and a polyethylene flat yarn 11b, and an electrode wire 12a electrically connected to the heat generating wire 11a. And a second yarn group 12 including a polyethylene flat yarn 12b. Specifically, the first yarn group 1
Using 1 as a warp yarn and 2nd yarn group 12 as a weft yarn, using a loom having the same configuration as usual, weaving it continuously as shown in FIG. It is manufactured by cutting the electrode strips 1a and 1a in which 12a is woven so that they are located at the position shown by the chain double-dashed line in FIG.

As the heating wire 11a, a narrow and thin tape-like one in which conductive particles such as carbon particles are dispersed in a binder resin having flexibility and heat resistance such as polytetrafluoroethylene ( For example, the product name “Fluorotron” manufactured by Daikin Industries, Ltd.) is used. As the polyethylene flat yarns 11b and 12b, thin and thin tape-shaped ones are used. As the electrode wire 12a, a core wire of spun rayon or the like in which a copper foil is spirally wound is used.

Next, the protective electrode sheet 2 comprises an insulating layer 2b formed by laminating resin films made of a polymer material that rapidly contracts when abnormal overheating occurs, and a sheet-shaped protective electrode 2a in this order. It is configured by stacking.
A flexible metal foil such as an aluminum foil is used as the protective electrode 2a. As the polymer material forming the insulating layer 2b, a thermoplastic resin having a melting point of 130 ° C. or higher and 170 ° C. or lower is preferably used. In particular, in the present embodiment, the adhesiveness with the woven heat generating sheet 1 and the protective electrode 2a Excellent in polypropylene, and its shrinkage and deformation due to heat are remarkable (melting point: approx. 16
What was stretched at 4 ° C. is more preferably used. Here, in the case where the insulating layer 2b is formed of a stretched polypropylene product which is significantly contracted and deformed by heat as in this embodiment, if abnormal overheating occurs for some reason, as shown in FIG. When the insulating layer 2b as a resin film is thermally contracted, the entire sheet heating element A is wrinkled and deformed. In this respect, in the conventional sheet heating element, since polyethylene terephthalate is adopted, not only the product becomes expensive, but also the deformation temperature (about 240 ° C) and the melting point (about 264 ° C) are too high. , The abnormal overheat could not be detected sufficiently. Further, when polyethylene is used as the insulating layer 2b, shrinkage deformation as shown in FIG. 4 cannot be caused, and the melting point (120 ° C.) is too low.
It was not suitable as an insulating member for the sheet heating element A that could be used up to about 30 ° C. However, the drawn product of polypropylene is only one example of a preferable material, and it has the above-mentioned predetermined melting point and is a material having a remarkable heat shrinkage,
Any resin material can be used. The front surface material 3 and the back surface material 4 are both sheet materials having an insulating property, and as shown in FIG. 5, a nonwoven fabric 31 (41), a polyethylene layer 32 (42), a polyethylene terephthalate layer 3
3 (43) and the polyethylene layer 34 (44) are laminated in this order. Surface material 3
Is laminated with the polyethylene layer 34 in contact with the upper surface of the protective electrode sheet 2, and the backing material 4 is laminated with the polyethylene layer 44 in contact with the lower surface of the woven heat generating sheet 1.

[0011]

EXAMPLE As a detector for detecting a short circuit between the heat generating sheet 1 and the protective electrode 2a, when a sheet or the like is accidentally stabbed by a needle or the like, the short circuit between the both is detected to detect the short circuit. The detector that shuts off the power supply to the heat generating sheet 1 can be used as it is. According to the sheet heating element A of the present embodiment having the above-mentioned configuration , the temperature control means is , for example, damaged due to some cause.
In case of trouble, the temperature exceeds the temperature controlled by the temperature control means.
When abnormal overheating of about 130 ° C. occurs, the entire surface heating element A is wrinkled and deformed due to thermal contraction of the insulating layer 2b as the resin film as described in FIG. The user of this for the planar heating element A, it is possible to visually that the abnormal overheating occurs, thereafter, abnormal
Without being aware of the risk of continued use,
By canceling, it is possible to prevent accidents such as scorching.

Further, in this embodiment, the insulating layer 2 is used.
Since the protective electrode 2a covers the entire surface of the heat-generating sheet 1 via b, even if the abnormal overheating is locally generated, the insulating layer 2b in that portion is melted to melt the heat-generating sheet 1 The short circuit between the protective electrode 2a and the protective electrode 2a, and the detector (not shown) can detect this short circuit to cut off the power supply to the textile heat generating sheet 1. As a result, it is possible to reliably detect local abnormal overheating. Moreover, since the insulating layer 2b is made of a stretched product of polypropylene, a portion where a short circuit is likely to occur locally due to heat shrinkage occurs. As a result, when the woven heat generating sheet 1 reaches the melting point of the insulating layer 2b, the portion is surely formed. There is an advantage that it melts and the short circuit with the woven heat generating sheet 1 becomes extremely reliable.

The structure of the sheet heating element of the present invention is not limited to the above-mentioned embodiment, and for example, the insulating layer 2b.
It goes without saying that various design changes can be made without changing the gist of the present invention, such as by constructing a single-layer resin sheet.

[0014]

As described above, according to the sheet heating element according to the first aspect of the present invention, when abnormal overheating occurs, the resin film or sheet is shrunk by heat so that the sheet heating element is entirely covered. It is possible to visually observe that wrinkles have occurred and abnormal overheating has occurred. Further, according to the planar heating element of the second aspect, the heat generation sheet and the protective electrode are likely to be locally short-circuited due to heat contraction, so that abnormal overheating can be detected more reliably with a simple structure. There are advantages.

Therefore, since the user of the sheet heating element according to the present invention can visually check that abnormal overheating has occurred or detect it by the detector, there is no possibility that the sheet will continue to be used after that, and there is no scorching. It is possible to prevent such accidents.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view showing an embodiment of a sheet heating element of the present invention.

FIG. 2 is a plan view of the woven heat generating sheet in the above-described embodiment.

FIG. 3 is a plan view showing continuous production of the woven heat generating sheet.

FIG. 4 is a perspective view showing a deformed state of the planar heating element.

FIG. 5 is a cross-sectional view showing a layer structure of a surface material (back surface material) used in the above examples.

[Explanation of symbols]

 A Sheet heating element 2b Insulation layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page Jury President Shiro Matsushima Judge Jumiko Niki Judge Norihiko Maeda (56) References JP-A-128389 (JP, A) JP-A-97390 (JP, A) Sho 61-66889 (JP, U) Japanese Patent Sho 60-21530 (JP, B2)

Claims (2)

(57) [Claims] 1. A temperature sensor, a heat generating sheet (1), and temperature control means for adjusting the temperature of the heat generating sheet (1) based on the temperature of the heat generating sheet (1) detected by the temperature sensor. Flexible sheet heating element
A heat-shrinkable resin film or resin sheet that shrinks visually at a predetermined temperature that causes abnormal overheating exceeding the temperature adjusted by the temperature control means is laminated on at least one surface of the heat-generating sheet (1) in a shrinkable state. A sheet heating element characterized by being 2. The heat-shrinkable resin film or resin sheet comprises a heat-generating sheet (1) and a heat-generating sheet (1).
The sheet heating element according to claim 1, which is an insulating layer (2b) made of polypropylene and laminated between the sheet-shaped protective electrode (2a) covering the entire surface.