JPH046787A - Planar heater - Google Patents

Abstract

PURPOSE:To prevent a current from flowing to the local overheat portion of an electrode from the non-local-overheat portion by forming one or more slits on a metal layer inserted between a positive-resistance temperature coefficient characteristic layer and a planar heating element. CONSTITUTION:Belt-shaped electrodes 12 are fixed at both side edge sections of a planar heating element. The electrode 12 has metal layers 14, 15 made of a metal thin piece such as a copper foil on both the upper and lower faces of a polymer layer (positive-temperature coefficient characteristic layer) 13 made of a PTC polymer composition material. Multiple slits 16 are formed along the lateral direction of the electrode 14 on the layer 13 and the lower metal layer 15. These slits 16 function as nonconducting portions of the metal layer 15, and the metal layer 15 is divided into multiple conducting portions When part of a planar heater is heat-isolated and its temperature rises for a local overheat, a current can be prevented from flowing to the local overheat portion of an electrode from the non-local-overheat portion.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a planar heater having a self-temperature regulating function.

``Conventional technology'' Conventional planar heaters use copper tape or silver conductive paint on a planar heating element made by applying carbon black/polymer-based conductive paste on an insulating base material such as glass cloth or polyester film. It is known that metal electrodes made of such as metal electrodes are provided so as to face each other. However, in such a planar heater, there is no change in electrical resistance between room temperature and high temperature. That is, Z T C (Z ero T emp
Erature Coefficient). Therefore, if a highly insulating material is placed on top of the planar heater, there is a risk that the temperature of the insulated portion may rise abnormally due to heat accumulation. Therefore, such a planar heater requires a separate temperature controller, overtemperature preventer, temperature fuse, etc. to control the temperature of the heat generated, which has the disadvantage of being cumbersome and expensive to handle.

Therefore, recently, a polymer composition layer (hereinafter simply P
This is called the TC polymer layer. ) is being considered. Here, the positive resistance temperature coefficient characteristic refers to the property that the resistance value increases as the temperature rises, and the PT
Also called C characteristic.

In this planar heater, due to the presence of the PTC polymer layer, when the temperature of the PTC polymer layer and the planar heating element increases due to heat storage by the heat insulating material, etc., when the temperature of the planar heating element exceeds a predetermined temperature, the PTC polymer layer By increasing the electrical resistance, the current flowing through the sheet heating element is controlled to reduce the amount of heat generated, resulting in a sheet heater having a self-temperature control function.

In addition, in order to bond an electrode body having a PTC polymer layer to a planar heating element with good conductivity and in a simplified manner, a PTC polymer layer was used.
Metal layers are integrally formed on both sides of the C polymer layer, and one of the metal layers is bonded so as to be in contact with the sheet heating element,
Planar heaters have been proposed that can be joined using various joining methods such as sewing.

FIG. 18 shows an example of such a planar heater, in which reference numeral 1 is a planar heating element, 2 is a PTC polymer layer, and 3 is a metal layer.

Furthermore, by configuring at least one surface of the sheet heater to be coated with a layer with good thermal conductivity (heat equalizing layer), variations in the temperature of each part of the heating element body are reduced, and temperature sensing by the PTC polymer layer is further improved. You can be sure.

"Problems to be Solved by the Invention" However, in the planar heater configured as described above, a heat insulating material 4 etc. is placed on the planar heater as shown in FIGS. 19 and 20. If there is an electrode part covered by a heat insulating material (the part indicated by a in Fig. 19) and an electrode part not covered by a heat insulating material (the part indicated by b in Fig. 19), the following problems may occur. occurs.

That is, (1) The temperature of the insulated part a becomes high due to local overheating. Therefore, the resistance of the PTC polymer layer also increases,
The current flowing to portion C is now controlled. but,
When there is a continuous metal layer between the PTC polymer layer and the planar heating element, the non-locally overheated portion of the electrode changes to the local overheated portion of the electrode a.
Current will flow into the metal layer through the metal layer, making it impossible to control the current in the C portion of the sheet heating element, which is locally overheated.

■In addition, 1 is added to the metal layer between the PTC polymer layer and the planar heating element.
Even if the above slits are formed to prevent current from flowing from the non-locally overheated part of the electrode to the locally overheated part a of the electrode, the resistance will increase at the same time as the temperature rises because the slit is covered with the insulating material 4. Since it is difficult for current to flow through the a portion of the electrode, current may flow diagonally through the sheet heating element from the locally overheated portion C of the sheet heating element to the bs portion of the electrode. Therefore, as in the case (2) above, current control (temperature control) cannot be performed in part of the C portion.

■In addition, one or more slits are formed in the metal layer between the PTC polymer layer and the planar heating element, and one or more slits (non-conducting part) are formed in the planar heating element, and the planar Even if current is prevented from flowing diagonally through the heating element, if the slits in the metal layer and the non-conducting part of the planar heating element are misaligned, the combined effects of (1) and (2) above will cause damage to the area under the heat insulating material 4. It is difficult to control the current in the heated portion, and there is a possibility that the temperature may rise above the target control temperature.

(2) It is considered difficult to match the non-conducting portion of the sheet heating element with the slit in the metal layer in terms of manufacturing the sheet heater. Therefore, it is necessary to ensure that the non-conducting portion of the sheet heating element and the slit in the metal layer coincide with each other, and to control only the portion where excessive temperature rise has occurred due to insulation of the sheet heating element.

"Means for Solving the Problems" The present invention has a planar heating element and at least one pair of electrodes provided on the planar heating element so as to face each other, and at least one of the electrodes is interposed between the positive temperature coefficient layer and the sheet heating element in a planar heater consisting of an electrode in which metal layers are integrally formed on both sides of a positive temperature coefficient layer (hereinafter referred to as the positive temperature coefficient layer). One or more slits were formed in the metal layer to form a planar heater, and this was used as a means for solving the above problem.

Further, it is desirable that the sheet heating element is provided with one or more non-conducting portions in the direction of current flowing through the sheet heating element.

Further, it is preferable that the non-conducting portion of the planar heating element and the slit of the metal layer be aligned with each other.

Furthermore, it is desirable that the distance from the starting end of the slit to the starting end of the next slit be set small relative to the width of the non-conducting portion.

"Function" By forming slits in the metal layer between the positive temperature coefficient characteristic layer and the planar heating element, a part of the planar heater is insulated, and when the temperature of the insulated part rises, the non-local part of the electrode Current can be prevented from flowing from the overheated portion to the locally overheated portion of the electrode.

In addition, by forming a slit in the metal layer between the positive temperature coefficient characteristic layer and the planar heating element, and forming a non-conducting part in the direction of the current flowing in the planar heating element, a part of the planar heater becomes When the temperature of the heat-insulating portion increases due to heating, current can be prevented from flowing from the locally overheated portion of the planar heating element to the non-locally overheated portion of the electrode.

Furthermore, by aligning the non-conducting part of the sheet heating element with the slit in the metal layer, a part of the sheet heater is insulated, and when the temperature of the insulated part rises, non-local overheating of the electrode occurs. It is possible to completely prevent the flow of current from the part to the locally overheated part of the electrode and the flow of current from the locally overheated part of the planar heating element to the non-locally overheated part of the electrode, and only the locally overheated part of the electrode is exposed to PTC. The current is controlled according to the characteristics, and the current is controlled in the part of the sheet heating element that conducts to it, and the part of the sheet heating element that conducts to other electrodes that are not locally overheated becomes normal. The fever state is maintained.

Furthermore, by setting the distance from the starting end of the slit in the metal layer to the starting end of the next slit to be smaller than the width of the non-conducting part of the planar heating element, when joining the electrode to the planar heating element, The position of the gap in the planar heating element and the position of the slit in the electrode can always be made to coincide.

Embodiment FIG. 1 shows a first example of a planar heater of the present invention, and reference numeral 11 in the figure is a planar heating element.

This sheet heating element is made by coating or impregnating carbon black/polymer-based conductive paste on the surface of an insulating base material such as a resin film such as polyester film or glass cloth, or by coating or impregnating the surface of an insulating base material with nichrome wire. A wire with a metal resistance wire, such as a metal resistance wire, running evenly across the wire and an insulating coating on top of the wire is used.

Band-shaped electrodes 12.
12 is fixed. This electrode 12 has a configuration in which metal layers 14 and 15 made of metal flakes such as copper foil are provided on both upper and lower surfaces of a band-shaped PTC polymer layer (positive resistance temperature coefficient characteristic layer) 13 made of a PTC polymer composition. There is. Among these metal layers 14 and 15, a metal layer 15 (hereinafter referred to as a lower metal layer) interposed between the PTC polymer layer 13 and the planar heating element 11 has a layer along the width direction of the electrode 14. A plurality of slits 16 are formed.

These slits 16 function as non-conducting portions in the lower metal layer 15 and are for dividing the lower metal layer 15 into a plurality of conductive portions.

These slits 16 only need to be spaced apart enough that adjacent conductive parts do not come in contact with each other and are electrically conductive, and usually 1
It is sufficient if it is at least mm. Further, the number of slits 16 formed and the interval between them are not particularly limited, and can be adjusted as appropriate depending on the dimensions of the planar heating element 11.

Furthermore, the PTC polymer layer 13 has PTC properties (
For example, a polymer composition material having a positive resistance temperature coefficient characteristic, such as a polyolefin polymer to which an appropriate amount of carbon black is added and molded, is used.

In this planar heater, slits 16 are formed in the gold 115 between the PTC polymer layer 13 and the planar heating element 11, so that a part of the planar heater is insulated and the temperature of the insulated part increases. However, when the locally overheated electrode part enters the current control state due to the PTC characteristic, the non-locally overheated part of the electrode (
It is possible to prevent current from flowing from the locally overheated portion of the electrode (symbol ■ in the same figure) to the locally overheated portion (symbol ■ in the same figure) of the planar heating element, and to control the current in the locally overheated portion (symbol ■ in the same figure) of the planar heating element. (temperature control) becomes possible.

FIG. 2 shows a second example of the planar heater of the present invention, which differs from the first example described above by using a plurality of planar heating element pieces 17 of two or more sheets. This is the configuration of the heating element 18. In this example, two planar heating element pieces 17.1
7 are arranged in parallel through a gap 19 to form a sheet heating element 18.
It consists of

This gap 19 forms a non-conducting part in the sheet heating element 18, and by forming this gap 19, the sheet heating element piece 1
7.17 are disposed intermittently, thereby dividing the planar heating element 18.

The above-mentioned band-shaped electrodes 12.12 are provided at both end portions of this planar heating element 18. Further, in this example, the slit 16 formed in the metal layer 15 below the electrode 12.12 and the gap 19 formed in the planar heating element 18 are shifted in position.

In this planar heater, the metal layer 15 has a sleeve) 16
... and a gap 19 in the planar heating element I8.
Since the planar heating element is divided into a plurality of planar heating element pieces 17, a part of the planar heater is insulated, the temperature of the insulated part increases, and the locally overheated electrode part is heated due to the PTC characteristic. To prevent current from flowing diagonally from the locally overheated portion of the planar heating element (symbol ■ in Figure 9) to the non-locally overheated portion of the electrode (symbol ■ in the same figure) when the current is in the current control state. Current control (temperature control) of locally overheated parts of sheet heating elements is possible.
This can be performed more reliably than with the planar heater according to the first example described above.

FIG. 3 shows a third example of the planar heater of the present invention, and the difference from the above-mentioned second example is that the planar heating element 18
The position of the gap 19 is made to coincide with one of the slits 16 formed in the metal layer 15.

In this example, the width of the gap 19 of the planar heating element 18 and the metal layer 1
Although the widths of the slits 16 of No. 5 are the same, these widths may not be the same. Further, the number of gaps 19 and slits 16 to be formed is not particularly limited, and it is also possible to form a plurality of gaps 19 in the planar heating element and make at least one gap 19 coincide with the slit 16 of the metal layer 15. be.

In this planar heater, the gap 19 of the planar heating element 18 is
Since the position of is made to coincide with the slit 16 of the metal layer 15, a part of the sheet heater is insulated, the temperature of the insulated part rises, and the locally overheated electrode part is brought into a current control state due to the PTC characteristic. When , current flows from the non-locally overheated part of the electrode (symbol ■ in Figure 12) to the locally overheated part of the electrode (symbol ■ in the same figure), and the local overheated part of the sheet heating element (symbol ■ in the same figure). From the non-local heating part of the electrode (symbol ■) to the non-local heating part of the electrode (symbol ■)
) can completely prevent the flow of current to
Only the locally overheated part of the electrode causes a current control state due to the PTC characteristic, and only the part of the sheet heating element that is electrically connected to it experiences a temperature drop, resulting in sheet heating that is electrically connected to other electrodes that are not locally overheated. The body parts remain in their normal state of fever.

FIGS. 4 and 5 show a fourth example of the present invention, and the difference from the third example described above is that the sheet heating element 18
The width of the slit 16 formed in the lower metal layer I5 of the electrode 12 is relative to the width of the gap 19 formed in
. . . is configured so that the distance from one slit starting end to the next slit starting end (indicated by Y in FIG. 5) is set to be small.

The relationship between the width X of the gap 19 and the distance Y from the starting end of one slit 16 to the starting end of the next slit 16 is expressed as X>Y
By setting the electrodes 12 and 12 at the gap 19 when joining the electrodes 12 and 12 to both side edges of the planar heating element 18,
It is possible to ensure that the two slits 16 coincide. Therefore, when manufacturing a sheet heater, the alignment operation between the gap 19 of the sheet heating element 18 and the slit 16 of the electrode 12 can be simplified, and the sheet heater can be manufactured easily. .

Note that the non-conducting part in this invention does not refer only to a part that has no electrical conductivity at all, but may also be a high-resistance part that has some electrical conductivity, and may also be a high-resistance part that has some electrical conductivity. If it has an electrical resistance at least 10 times or more, preferably 100 times or more, the same effect as the gap 19 on each side described above can be obtained.

A specific example will be shown below.

(Experimental Example 1) A planar heater having the structure shown in FIGS. 6 and 7 was manufactured. As the planar heating element 11, a conductive paste in which highly conductive carbon fine particles are uniformly dispersed on a polyester face is applied to the entire surface of the insulating base layer of the polyester film.
I used one made by baking. For the PTC polymer layer, 25% by weight of acetylene black is added to the ionomer resin.
A resin composition prepared by adding a small amount of anti-aging agent was extrusion-molded to form a sort with a thickness of 0.3+ nm.

As the metal layers 14 and 15, tin plated copper foil with a thickness of 50 μm was used. The dimensions of the sheet heating element 11 are 100I x 253
III11 PTC polymer layer 13 and metal layer 14.
The width of 15 is 12.5μI, and the lower metal layer 1
A slit 16 with a radius of 1OIII11 is placed approximately in the center of 5.
One was formed.

This planar heater is placed on a urethane foam 20 with a thickness of 50 cm as shown in FIG.
, a voltage of 100V was applied to cause the planar heating element to generate heat.

Moreover, the room temperature at this time was 20°C. After the temperature of the planar heating element reaches a steady state after 15 minutes have elapsed after electricity is applied, a portion of the top surface of the planar heater is coated with a thickness of 50+ nm as shown in Fig. 7.
urethane foam 21 was placed, and only this portion was locally insulated to create a state of local overheating.

FIG. 8 shows the results of measurements of temperature changes at each position ① to ① of the planar heating element and electrodes shown in FIG. 6 from the start of current application.

(Experimental Example 2) A planar heater having the structure shown in FIG. 9 and FIG. 1θ was manufactured. Experimental example! The same material used in , with dimensions 4
A sheet heating element 18 was prepared by arranging two sheet heating element pieces measuring 5 mm x 253 mm in parallel and forming a gap 19 of 10 mm between them. The same PTC polymer layer 13 and metal layers 14 and 15 as in Experimental Example 1 were used. Further, two slits with a diameter of 10III++ are arranged in the metal layer 15 on both sides of the gap 19 so as not to coincide with the gap 19 of the planar heating element 18.

Using this sheet heater, in the same manner as in Experimental Example 1, after the temperature of the sheet heating element reached a steady state 15 minutes after energization, the upper surface of the sheet heater was heated as shown in FIG. A urethane foam 21 with a thickness of 50 mm was placed on a portion of the tube, and only this portion was locally insulated to create a state of local overheating.

FIG. 11 shows the results of measurement of temperature changes at each position ① to ① of the planar heating element and electrodes shown in FIG. 9 from the start of current application.

(Experimental Example 3) A planar heater having the structure shown in FIGS. 12 and 13 was manufactured. Two sheet heating element pieces identical to those used in Experimental Example 2 were arranged in parallel, and a gap 19 of 10 μm was formed between them to produce a sheet heating element 18. The PTC polymer layer 13 and metal layers 14 and 15 were the same as in Experimental Example 1. Further, a slit 16 having a width of 1OfflI11 was formed in the center of the metal layer 15, and the slit 16 and the gap 19 of the planar heating element 18 were made to coincide with each other.

Using this sheet heater, in the same manner as in Experimental Example 1 described above, after the temperature of the sheet heating element reached a steady state 15 minutes after energization, as shown in FIGS. 12 and 13, A urethane foam 2 with a thickness of 50III11 is placed so as to cover a part of one heating element piece 17(1) and the upper surface of one electrode part.
1 was placed, and only this part was locally insulated to create a state of local overheating.

FIG. 14 shows the results of measurements of temperature changes at each position ① to ① of the planar heating element and electrodes shown in FIG. 12 from the start of energization.

As is clear from FIG. 14, the electrode part at the locally overheated position (■) enters the current control state due to the PTC characteristic, and the first
The temperature of the heating element piece 57(I) on the overheated side in FIG. 2 decreases, while the heating element piece 17 on the side that is not locally overheated
The temperature of (U) is almost constant. Therefore, it can be seen that the heating element piece 17 (II) on the side that is not locally overheated operates normally without being affected by the local overheating of the heating element piece 17 (1) on the side that is locally overheated.

(Comparative Example) As shown in FIGS. 15 and 16, the same planar heating element 1 as used in Experimental Example 1 was used, and the metal layer 3 of the electrode was also not formed with slits. A heater was created.

Using this sheet heater, after the temperature of the sheet heating element reached a steady state 15 minutes after energization, as in each of the above-mentioned experimental examples, the upper surface of the sheet heater was heated as shown in Fig. 16. A urethane foam 21 with a thickness of 50Illal is placed in a part, and only this part is locally insulated to create a state of local overheating, and the temperature change at each position of the sheet heating element piece and the electrode is measured from the time when the current is started. did. The results are shown in FIG.

"Effects of the Invention" As explained above, the planar heater of the present invention has PTC
Since a slit is formed in the metal layer between the polymer layer (positive resistance temperature coefficient characteristic layer) and the planar heating element, a part of the planar heater is insulated, and when the temperature of the insulated part rises, the non-local part of the electrode It is possible to prevent current from flowing from the overheated part to the locally overheated part of the electrode, and it becomes possible to control the current (temperature control) in the locally overheated part of the planar heating element.

In addition, a slit is formed in the metal layer between the PTC polymer layer and the sheet heating element, and a non-conducting part is formed in the sheet heating element in the direction of the current flowing, so a part of the sheet heater is insulated. When the temperature of the area rises, it is possible to prevent current from flowing from the locally overheated area of the planar heating element to the non-locally overheated area of the electrode, and to control the current (temperature control) of the locally overheated area of the planar heating element. ) can be performed more reliably.

Furthermore, since the non-conducting part of the sheet heating element and the slit in the metal layer are aligned, a part of the sheet heater is insulated.
When the temperature of the insulation part increases, the flow of current from the non-locally overheated part of the electrode to the locally overheated part of the electrode and from the locally overheated part of the sheet heating element to the non-locally overheated part of the electrode is completely stopped. Therefore, only the local overheating part of the electrode is in a current control state due to the PTC characteristics, and the current control of the part of the planar heating element that is electrically connected to it is ensured, and other local overheating can be prevented. The portion of the planar heating element that is electrically connected to the electrodes that are not connected to the other electrodes maintains its normal heating state.

Furthermore, the distance from the starting end of the slit in the metal layer to the starting end of the next slit is set small relative to the width of the non-conducting part of the planar heating element, so when joining the electrode to the planar heating element, there is no gap. The position of the electrode can be matched with the position of the slit of the electrode. Therefore, when manufacturing a sheet heater, it is possible to simplify the alignment operation between the non-conducting part of the sheet heating element and the slit of the electrode, which has the effect of facilitating the manufacture of the sheet heater. .

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a first example of a sheet heater of the present invention, FIG. 2 is a perspective view of a second example of a sheet heater of this invention, and FIG. 3 is a perspective view of a sheet heater of this invention. FIG. 4 is a perspective view showing a fourth example of the present invention, and FIG.
The figure is an enlarged sectional view of the main part of the planar heater shown in FIG. 4, and FIGS. 6 to 8 are diagrams for explaining Experimental Example 1,
Fig. 6 is a plan view of the sheet heater, Fig. 7 is a side view of the same, and Fig. 8 is a plan view of the sheet heater.
The figure is a graph showing the temperature change of each part in the planar heater of Experimental Example 1, FIGS. 9 to 11 are diagrams for explaining Experimental Example 2, and FIG. 9 is a plan view of the planar heater, 1st
Figure O is a side view of the same side, Figure 11 is a graph showing temperature changes at various parts in the sheet heater of Experimental Example 2, Figures 12 to 1 are
Figure 4 is a diagram for explaining Experimental Example 3, in which Figure 12 is a plan view of the sheet heater, Figure 13 is a side view of the same, and Figure 14 is the temperature of each part of the sheet heater of Experimental Example 3. Graphs showing changes, FIGS. 15 to 17 are diagrams for explaining comparative examples, and FIG. 15 is a plan view of the sheet heater, and FIG.
6 is a side view of the same side, FIG. 17 is a graph showing the temperature change of each part in the planar heater of the comparative example, FIG. 18 is a diagram showing the conventional planar heater, and FIGS. 19 and 20 are the graphs shown in FIG. FIG. 19 is a plan view of the sheet heater, and FIG. 20 is a side view thereof. 11.18... Planar heating element 12... Electrode 13... PTC polymer layer 14.15... Metal layer 16... Slit 17... Planar heating element piece 19... Gap (non-conducting part)

Claims (4)

[Claims] (1) It has a planar heating element and at least one pair of electrodes provided on the planar heating element so as to face each other, and at least one of the electrodes is provided on both sides of the positive resistance temperature coefficient characteristic layer. A planar heater consisting of an electrode integrally formed with a metal layer, characterized in that a slit on one side is formed in the metal layer interposed between the positive resistance temperature coefficient characteristic layer and the planar heating element. Planar heater. (2) The planar heater according to claim 1, wherein the planar heating element has one or more non-conducting portions formed in the direction of current flowing through the planar heating element. (3) The planar heater according to claim 2, wherein the non-conducting portion and the slit are aligned in position. (4) The planar heater according to claim 3, wherein the distance from the starting end of the slit to the starting end of the next slit is set to be smaller than the width of the non-conducting portion.