JPH10302942A - Planar heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a planar heater capable of easily reducing a resistance value, obtaining desired power consumption even at a low voltage, easily heating a whole planar heating element uniformly, and further facilitating waterproof easily. SOLUTION: On a flexible board 20, two pairs of comb-gear shaped electrode patterns 40 and 50 are formed so that both of comb gears 43 and 53 are geared with each other, and there is provided a planar heating element 10 in which between the adjacent comb gears 43 and 53 of both of the electron patterns 40 and 50 is coupled with a resistor patterns 30 (35) for heating of a plurality of stripe shape. This planar heating element 10 is sealed with waterproof sheets 60 and 70.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar heater used for preventing fogging of a mirror.

[0002]

2. Description of the Related Art Conventionally, the entire surface of a substrate is heated (for example, 30 degrees).
(40 ° C. to 40 ° C.) are used for applications such as, for example, fogging of mirrors. That is, if a sheet heater is attached to the back surface of the portion of the mirror where fogging is to be prevented, the portion heated by the sheet heater can be prevented from fogging.

Conventionally, there are various types of planar heaters having various structures. As shown in FIG. 7, a planar heater on a flexible substrate 201 has a simple structure, is easy to manufacture, and can easily cope with a curved surface. A pair of silver paste electrode patterns 203 and 205 are screen-printed in parallel in the vicinity of opposing opposite sides of the substrate, and a heating resistor pattern 207 made of carbon paste is screened so as to connect the electrode patterns 203 and 205 to each other. A printed structure is proposed.

In the above conventional example, the electrode patterns 203,
205 is formed by screen printing of a silver paste without being formed by copper foil etching having a small resistance value. In the case of copper foil etching, etching and cost are troublesome (expensive materials, many steps, waste liquid management). Problem, waste of copper resources discarded by etching).

[0005]

However, the above-mentioned prior art has the following problems.

[0006] Since the width a of the resistor pattern 207 is long, the resistance value between the two electrode patterns 203 and 205 increases accordingly.

On the other hand, in the case of a planar heater or the like to be mounted on a mirror or the like in a bathroom, it is necessary to lower the voltage value for safety.
If lowering the only voltage value V power consumption W as remains constant, there is a relation of WR = V ^2, it shall significantly reduce the resistance value R. Specifically, voltage value 1
When it is 00V and power consumption is 26W, the resistance value is about 385Ω
On the other hand, when the voltage value is 20 V and the power consumption is 26 W, the resistance value is about 15Ω.

However, when a carbon paste is used as the resistor pattern 207 as in the above conventional example,
Due to its material, the resistance could not be reduced too much.

When this planar heater is used, for example, in a bathroom, water droplets may adhere to the resistor pattern 207 of the planar heater, and the resistor pattern 20
Not only does the effective heat generation not occur due to a large change in the resistance value of No. 7, but there is also a risk of short-circuiting.

The present invention has been made in view of the above points, and has as its object the purpose of easily reducing the resistance value, obtaining desired power consumption even at a low voltage, and uniformly heating the entire sheet heating element. It is another object of the present invention to provide a planar heater which can easily perform the waterproofing and can easily achieve the waterproofing.

[0011]

In order to solve the above-mentioned problems, a planar heater according to the present invention comprises a planar heating element formed by printing a resistor pattern for heating on a substrate. The heating element was hermetically sealed with a waterproof sheet. Further, the planar heater according to the present invention has a comb-shaped 2
A set of electrode patterns is formed so that both comb teeth mesh with each other, and a planar heating element having a heating resistor pattern formed so as to connect between adjacent comb teeth of both electrode patterns. Configured. In this case, it is preferable that the resistor pattern is a resistor pattern having a large number of stripes.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is an exploded perspective view of a planar heater according to one embodiment of the present invention. As shown in the figure, this planar heater is configured by sealing the upper and lower surfaces of the planar heating element 10 with waterproof sheets 60 and 70. Hereinafter, each component will be described.

FIG. 2 is an exploded perspective view of the sheet heating element 10. As shown in FIG. 1, the planar heating element 10 is formed by screen-printing two sets of electrode patterns 40 and 50 on a flexible substrate 20 and screen-printing a resistor pattern 30 thereon. I have.

Here, as the flexible substrate 20, a flexible resin film such as a polyethylene terephthalate film is used.

The electrode patterns 40 and 50 respectively have a plurality of comb teeth 43 and 53 projecting in parallel from one main pattern 41 and 51 at equal intervals, and the two projecting comb teeth 43 and 53 are projected.
Are formed so as to alternately and in parallel mesh with each other, and specifically, are formed by screen-printing a silver paste on the flexible substrate 20.

On the other hand, the resistor pattern 30 includes resistor patterns 31 and 31 having a shape covering the main patterns 41 and 51 of the electrode patterns 40 and 50, and a resistor pattern having a shape covering the comb teeth 43 and 53. 33 and a plurality of resistor patterns 35 connecting the adjacent parallel resistor patterns 33 in a stripe shape (ladder shape). Specifically, the electrode patterns 40 and 50 are formed. Is formed by screen-printing a carbon paste on the flexible substrate 20 on which is printed.

The resistor patterns 31 and 33 are composed of the main patterns 41 and 51 of the electrode patterns 40 and 50.
And the comb teeth 43 and 53 are electrically protected, and the striped resistor pattern 35 electrically connects the adjacent comb teeth 43 and 53 of the electrode patterns 40 and 50. Therefore, in FIG. 1, the description of the resistor patterns 31 and 33 is omitted to clarify the electrical configuration, and the main patterns 41 and 51 of the electrode patterns 40 and 50 and the comb teeth 4 are omitted.
3, 53 are shown as exposed.

Returning to FIG. 1, two main patterns 4
A lead wire 80 is connected to one end of each of the sheet heating elements 1 and 51 (the connection structure is simplified in FIG. 1 but is actually a structure described in detail below).
Waterproof sheets 60 and 70 made of a thermoplastic resin sheet (for example, a polypropylene sheet) are laminated on the upper and lower surfaces, and the entire outer peripheral portion of the waterproof sheets 60 and 70 protruding from the planar heating element 10 is heat-sealed and bonded. Thus, the sheet heating element 10 is sealed. Note that sealing may be performed using an adhesive or the like instead of the heat seal bonding.

On the other hand, the lead wire 80 penetrates through the hole 61 provided in the one waterproof sheet 60, further penetrates the hole 87 of the cap 85, and the cap 87 is brought into contact with the upper surface of the waterproof sheet 60. Is sealed by the following method.

FIG. 3 is a sectional side view of a main part showing a structure for connecting the lead wires 80 to the main patterns 41 and 51 and a waterproof structure using a cap 87. The flexible substrate 20
The leading end portions of the main patterns 41 and 51 are notched by a U-shaped cut line Y as shown by a dotted line in FIG.

The cut-out tongue-shaped portion is drawn out to the front side through slits 111 and 113 provided in a backing plate 110 mounted on the upper surface of the flexible substrate 20, as shown in FIG. The metal plates 121 and 123 and the contact plates 131 and 133 are placed thereon, respectively, and these are integrally fixed by eyelet terminals 141 and 143.

Then, lead wires 80 (81, 83) are soldered to the portions of the metal plates 121, 123, and penetrate through the hole 61 of the waterproof sheet 60 and the hole 87 of the cap 85. Between the seat 60 and the cap 8
5 between the hole 87 and the lead wire 80.
Seal with 1,153.

As a result, the sheet heating element 10 shown in FIG. 1 is completely sealed in the waterproof sheets 60 and 70. Therefore, even if the sheet heater is used for a mirror or the like in a bathroom, the waterproof sheet 60 can be used. , 70, there is no danger that water will penetrate into the surface and adhere to the planar heating element 10, and therefore the resistance of the planar heating element 10 will not change.

Next, in the case of the planar heating element 10, the resistance value can be made smaller than in the conventional example, and the resistance value of each part can be made uniform. The reason will be described below.

That is, in this embodiment, as shown in FIG. 1, the electrode patterns 40 and 50 are provided with comb teeth 43 and 53,
Since the resistor pattern 35 is provided so as to connect the adjacent comb teeth 43 and 53, the length of the resistor pattern 35 connecting the comb teeth 43 and 53 can be shortened. Therefore, the resistance value between the two electrode patterns 40 and 50 can be reduced as compared with the conventional example shown in FIG.

Therefore, even if the voltage applied between the two electrode patterns 40 and 50 is small, desired power consumption can be obtained.

When the purpose is only to reduce the resistance value, the resistor pattern 35 is not formed in a stripe pattern, but as shown in FIG. What is necessary is just to connect by the pattern 35 '.

However, in this case, if the electrode patterns 40 and 50 are made of copper foil etching, the current flows mainly through the shortest distance h of the resistor pattern 35 'since the resistance value is small. As in the embodiment, the entire surface can be substantially uniformly heated. However, when silver paste is used for the electrode patterns 40 and 50, the resistance value is about 100 times larger than that of the copper foil etching, and the difference between the resistance value and the resistance value of the resistor pattern 35 'is small. Therefore, the current mainly flows through the short path g. For this reason, the temperature distribution of the entire surface varies. Therefore, in the embodiment of FIG. 1, in order to solve this problem, the resistor pattern 35 is used.
Are formed in a stripe shape so that the current always flows in the h direction shown in FIG. 5, thereby making the current flowing through the entire surface substantially uniform and preventing the temperature distribution from varying.

FIG. 6 is an enlarged plan view of the main parts of the electrode patterns 40 and 50 and the resistor pattern 35. In FIG.
3 and 53 are the same, and the length of the resistor pattern 35 passing therethrough is the same.
The resistance value is the same even after passing through f. Therefore, the same current flows through all of the resistor patterns 35 to generate the same amount of heat. From this point as well, the heat generation temperature of each part can be made uniform.

The comb teeth 43 and 45 and the resistor pattern 35 provided at positions away from the portion where the lead wires 80 are connected as shown in FIG. 1 are closer to the comb teeth 43 and 45 provided at positions closer to the lead wires 80. The electrode patterns 4 formed on both sides of the flexible substrate 20 than the electrode patterns 45 and the resistor pattern 35
The resistance increases as the length of 1, 51 increases, making it difficult for current to flow.

Therefore, in order to further uniform the heat generation temperature distribution in each part, the interval between the comb teeth 43, 45 provided at a position distant from the part to which the lead wire 80 is connected is reduced, or the comb teeth 43, 53 are provided. The current flowing by reducing the resistance value is reduced by making improvements such as narrowing the interval between the resistor patterns 35 connecting them and increasing the width of each resistor pattern 35. The power consumption of each unit may be increased to make the power consumption uniform.

Although the embodiments of the present invention have been described in detail, the present invention is not limited to these embodiments, and for example, the following modifications are possible.

In the above embodiment, an example is shown in which the electrode patterns 40 and 50 are formed using a silver paste having a large electric resistance value. Instead, the electrode patterns 40 and 50 are formed by etching a copper foil. Needless to say, it is also possible to use.

In the above embodiment, a flexible substrate is used as the substrate, but a hard substrate may be used.

[0035]

As described in detail above, the present invention has the following excellent effects. Since the sheet heating element is sealed with a waterproof sheet, it can be easily waterproofed.

The resistance between the two electrode patterns can be easily reduced, and desired power consumption can be obtained even at a low voltage.

The entire sheet heating element can be heated uniformly.

The above-mentioned effects can be achieved even by using inexpensive screen printing, although the specific resistance of the electrode pattern is relatively large, and the manufacturing cost can be reduced.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a planar heater according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view of the sheet heating element 10. FIG.

FIG. 3 is a sectional side view of a main part showing a structure for connecting lead wires 80 to main patterns 41 and 51 and a waterproof structure using a cap 87;

FIG. 4 shows main patterns 41 and 51 of a flexible substrate 20.
FIG. 4 is an enlarged perspective view of a main part showing a portion provided with a tip end of FIG.

FIG. 5 shows electrode patterns 40 and 50 according to another embodiment.
FIG. 9 is a perspective view showing a resistor pattern 35 '.

FIG. 6 shows electrode patterns 40 and 50 and a resistor pattern 35.
3 is an enlarged plan view of a main part of FIG.

FIG. 7 is a plan view showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Planar heating element 20 Flexible board 30 (35) Resistor pattern 40, 50 Electrode pattern 43, 53 Comb tooth 60, 70 Waterproof sheet

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Hiroshi Nerima 335 Karuku, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture Imperial Telecommunications Industry Co., Ltd.

Claims (3)

[Claims] 1. A sheet heater comprising: a sheet heating element formed by printing a heating resistor pattern on a substrate; and sealing the sheet heating element with a waterproof sheet. 2. A pair of comb-shaped electrode patterns are formed on a substrate so that both comb teeth mesh with each other, and furthermore, a pair of comb-shaped electrode patterns for heat generation are connected so as to connect adjacent comb teeth of the both electrode patterns. A planar heater comprising a planar heating element formed with a resistor pattern. 3. The planar heater according to claim 2, wherein adjacent comb teeth of the two sets of electrode patterns are connected by a multiplicity of striped resistor patterns.