JPS62103996A - Plane heating unit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention can generate a large amount of heat even when connected to a low voltage power supply, and can provide a desired temperature distribution. The present invention relates to a planar heating element, and more particularly relates to a planar heating element in which the heating circuit is made up of alternating partial circuits made of two or more types of conductive materials having different resistance values.

(Prior art, problems to be solved by the invention) Conventionally,
In a planar heating element manufactured by a method of forming a heating circuit by printing between electrodes on a base material using conductive ink, all the heating circuits are uniformly printed with the same conductive ink. The resistance value R and the amount of heat generation W of such a heating circuit are expressed as follows. That is, R-βL/BN ・・・・・・・・・・・・・・・・・・
・・・・・・・・・(1) W=V/R・・・・・・
・・・・・・・・・・・・・・・・・・・・・(2) Here, β represents the resistance value of the conductive ink used in the heat generating circuit in area resistance (0 inlets), L is the length of the heat generating circuit, B is the width of the line of the heat generating circuit, N is the number of heat generating circuits, and V is the voltage applied to the electrode. The calorific value W of the planar heating element is (2
As can be seen from Equation 1, the resistance can be increased by reducing the resistance value to R1. Further, in order to reduce the resistance value, it is understood from the formula (tl) that K should be reduced to β, Ll and 81N should be increased. However, within a predetermined size range, increasing the line width B reduces the number N of lines that can be arranged, so the range in which R can be adjusted by 81N is small. Also, as for the length of the wire, it is impossible to make it shorter than the distance between the electrodes, so if you want to reduce %R, there is no other way than reducing only I, that is, using a conductive material with a low resistance value. There was no. However, the lowest resistance value of conductive ink for heating elements generally available on the market is around 100%. Since ink for heating elements with low resistance is not available,
There were disadvantages such as the inability to manufacture a desired planar heating element.

In addition, the surface temperature distribution of a planar heating element is determined by the equilibrium state between heat generation and heat radiation. The temperature will be higher than the surrounding area, and if it is installed vertically, the temperature at the top will be higher than the bottom, and in either case there are disadvantages such as uneven temperature distribution.

As mentioned above, there is a limit to the resistance value of conventional conductive ink for heating elements, so there was a natural limit to the production of planar heating elements with low resistance values that can generate sufficient heat with a low voltage power supply. . Furthermore, conventional planar heating elements have problems such as uneven temperature distribution depending on how they are used.

(Means and effects for solving the problem) The present invention provides a planar heating element in which electrodes and a heating circuit are arranged on a base material, in which the heating circuit interposed between the electrodes has two or more types of different resistance values. This sheet heating element is characterized in that partial circuits made of conductive material are alternately connected.

The base material and electrodes of the sheet heating element of the present invention are the same as those of the conventional sheet heating element. That is, the base material is a polyester film, a polycarbonate film, a polyether resin film, a mica plate, or the like. In addition, the electrodes are printed with conductive paste such as silver paste or copper paste, metal spraying, or metal vapor deposition.

These include things that have been done.

The heating circuit in the planar heating element of the present invention is formed by alternately connecting partial circuits made of conductive materials with different resistance values. Generally, conductive ink is used as the conductive material, and ink for heating elements is used as a conductive ink with a relatively high resistance value, and ink for conductive circuits is used as an ink with a relatively low resistance value. For both, materials known per se are used. The ink for the heating element is prepared by kneading carbon powder such as carbon black or graphite with thermosetting resin such as epoxy resin or phenol resin and has a sheet resistance of about 1 Ω to IOK Ω, preferably 10 Ink of approximately Ω0 is used for ports 5 to 5. There is a city. Ink for conductive circuits is prepared by kneading silver powder, silver/radium powder, copper powder, etc. and thermosetting resin such as epoxy resin or phenol resin, and preferably has a sheet resistance of about 10 to 1000. About 1000 ink is used. Commercially available products include DuPont's 4922 (sheet resistance 100).

Furthermore, a conductive ink having a resistance value intermediate between the carbon-based or graphite-based inks and the metal-based inks can also be used.

As the conductive material, the above-mentioned conductive ink is generally used, but in addition to the conductive ink, for example, partial circuits formed by etching metal foil, metal vaporized film, etc., partial circuits formed by etching etching, etc. However, this does not preclude its use as a conductive material in the present invention.

By appropriately selecting the length, arrangement order, etc. of the partial circuits, a planar heating element with desired heat generation Jt and temperature distribution can be obtained. These will be explained in more detail with reference to embodiments shown in the drawings.

(Example) FIG. 1 is an example of a plan view of a planar heating element.

That is, two electrodes 2.2 are arranged along both edges of the rectangular base material IiIiK1 base material 10, and a plurality of linear heating circuits are arranged between these electrodes 2.2 perpendicularly to the electrodes. 3. ..., 3 is interposed (however,
(The heating circuit in the center is omitted).

2 to 5 are enlarged views of the heating circuit of the conventional sheet heating element shown in FIG. 1, which are uniformly printed to show details of the heating circuit of the sheet heating element. 3 to 5 are examples of heating circuits in the planar heating element of the present invention. That is, the side heating circuit 3 has a portion printed with carbon-based heating element ink (hereinafter referred to as partial circuit A) 4°4,.
......, 4 and the part printed with metal-based conductive circuit ink (hereinafter referred to as partial circuit B) 5,5°...
, 5 are alternately connected in series. 1st
In the planar heating element shown in the figure, if the heating circuit has a line width B and length and N conventional heating circuits shown in FIG. 2 are arranged, then the resistance value R of this heating circuit As shown in equation (1), is βL/BN. In addition, in the planar heating element shown in FIG. 1, the fir 11 of the circuit is B, and the length is L. ．． ......, the unit length of 4 is 11 s, the unit length of partial circuit B5 is 2, and N heating circuits are arranged in which each partial circuit is alternately connected in series with UfW. is the resistance value R° of this sheet heating element.
is expressed as follows.

R'=U(βl+/B+β'l 2/B )/N=R
(β11 +β'12)/IC11+lz')...(
3) Here, β is the sheet resistance of the carbon-based heating element ink, and β1 is the sheet resistance of the metal-based conductive circuit ink. Further, when K is the ratio of 12/11, equation (3) can be expressed as follows.

R'=RX(β+β'K)/β(1+K)...
(4) For example, the sheet resistance value β of a carbon-based ink for a heating element is 100 units, and the sheet resistance value β1 of a metal-based ink for a conductive circuit is approximately 10 Ω0. When the ratio K of 12/11 is about 1 to 100, β1
Since the value of is in the range of 1 to o, o196 of the value of β and can be virtually ignored, equation (4) can be approximated as follows.

R' = R/(1+K)・・・・・・・・・・・・
...(5) That is, when the ratio of lz/l+ is set to K, the heat generating circuit of the present Jl has a resistance value of approximately 1/(1+K) compared to the conventional heat generating circuit, and therefore the same It can be seen that the amount of heat generated by the heating circuit increases even at vOTL pressure. In this case, the resistance value of the metal-based conductive circuit ink is extremely small compared to the resistance value (C) of the carbon-based heating element ink, and in the partial circuits connected in series, the voltage (divided voltage) applied to each partial circuit is ) is proportional to the resistance value of each partial circuit, so the voltage (partial pressure) applied to the partial circuit made of metal-based conductive circuit ink is extremely small and virtually does not generate heat; Only the circuit generates heat. Therefore, if the length of 12 is too long, it may cause temperature unevenness.It depends on the printing substrate and the usage environment of the planar heating element, but in order to avoid this temperature unevenness, l! 2 is preferably 10+n or less, and 11 is preferably 0.1fi or more in terms of printing accuracy.Therefore, in the heat generating circuit according to the present invention, 11 is 0.
．． When 111%12 is 101111, it is possible to manufacture a planar heating element with a resistance value of 1/100 or more of the conventional heating circuit from equation (4) where the ratio K of It/11 is 100 or less. I understand.

The heating circuit 6 in FIG. 4 is the length of the partial circuit A4 and the length of the partial circuit B.
An example of a case where the ratio to the length of 5 is partially changed is shown. That is, the partial circuits A4 are aligned in a straight line, the length Itl of the partial circuit 4 is constant, the ratio of 12/It of the heat generating circuit is increased in the center, and the ratio of 12/11 of the heat generating circuit is successively decreased as it approaches the electrode. By doing so, the temperature distribution can be made uniform when the planar heating element is installed horizontally and used.

FIG. 5 shows an example in which the heating circuits shown in FIG. 3 are arranged in a checkered pattern with every other heat generating circuit shifted. When the ratio l z /l 1 is large, the distance between the heat generating spots can be made small, thereby achieving the effect of preventing temperature unevenness.

In addition, when forming a heat generating circuit using two types of ink with a resistance value ratio of about 10 times or less, both partial circuits generate heat, so temperature unevenness is less likely to occur.
There is no problem even if the number is 11 or more, and by alternately connecting partial circuits with different resistance values of 3111 or more in series, it is also possible to provide a fine temperature distribution.

(Effects of the Invention) As explained above, the present invention expands the resistance value limit of a sheet heating element to a far greater extent than that of the conventional sheet heating element. It is possible to greatly increase the amount of heat generated and to freely change the temperature distribution, which is useful for diversifying the functions of sheet heating elements.

[Brief explanation of drawings]

FIG. 1 is an example of a plan view of a planar heating element, and FIGS. 2 to 5 are partially enlarged views of the heating circuit of the planar heating element shown in FIG. In the drawings 1...Base material 2...Electrode 6...Heating circuit 4
... Partial circuit using ink for heating element (partial circuit A) 5... Partial circuit using ink for conductive circuit (partial circuit B)
) B...Width of the wire of the heat generating circuit L...Length of the heat generating circuit 11...Length of partial circuit A4 It2...Length of partial circuit B5. Patent applicant: Mitsubishi Gas Chemical Co., Ltd. Representative: Kazuyoshi Nagano

Claims (1)

[Claims] In a planar heating element in which electrodes and a heating circuit are arranged on a base material, the heating circuit interposed between the electrodes is made up of alternating partial circuits made of two or more types of conductive materials with different resistance values. Features a sheet heating element.