JPH0958418A - Rear view mirror for vehicle - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To increase the thermal conductivity from a sheet heating element to a mirror and to accelerate the temperature rise, and to defrost and defrost by uniformly raising the temperature on the entire surface of the mirror, and to simplify the assembly man-hours and reduce the cost. Is to reduce. SOLUTION: An insulating film 21 is directly formed by printing on the back surface of the mirror 1, and a conductive film 22 for electrodes and a resistive film 23 for heat generation are printed and laminated on the insulating film 21 to form a heat generating circuit. A pressure-sensitive adhesive layer 24 is formed on the heating circuit by printing, coating, or the like, and an insulating protective film 25 is formed by printing, coating, or attaching via the pressure-sensitive adhesive layer 24. A sheet heating element is constituted by.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rearview mirror for a vehicle such as an automobile, and more particularly to a rearview mirror for a vehicle in which a heating element is provided on the back surface of the mirror to prevent fogging.

[0002]

2. Description of the Related Art A conventional rear view mirror for a vehicle having a heating element attached to the rear surface of a mirror is shown in FIG. 7, a side view thereof is shown in FIG. 8 and a partially enlarged view thereof is shown in FIG. The mirror 1 has a reflection film 1b formed on the back surface of the glass 1a, and a surface heating element 2 is adhered to the back surface of the mirror 1. The sheet heating element 2 includes an adhesive layer 2a, a polyester film 2b, an adhesive layer 2c,
It is composed of 6 layers of a resistance film 2d for heat generation, a conductive film 2e for electrodes, and a polyester film 2b, and is attached to the mirror 1 via an adhesive layer 2a. A code 3 is soldered to the electrode conductive film 2e, and has a connector 4 at its tip.

[0003]

As described above, since the conventional rearview mirror for a vehicle is constructed by attaching the sheet heating element (heater) 2 to the mirror 1, a lot of manpower is required for the work and the cost is reduced. There was a drawback to up. Further, it was difficult to automate the attachment of the heater part. Further, structurally, since the adhesive layers 2a and 2c are interposed between the mirror 1 and the heater 2, the thermal conductivity is poor, and it takes time for the temperature on the mirror surface to rise, resulting in poor thermal efficiency.

The object of the present invention is that the heat conductivity to the mirror is excellent, the heat efficiency is good, the temperature rise of the mirror surface can be heated quickly and uniformly, and the manufacturing process is easy and the assembly process is simple. And cost reduction.

[0005]

The above object is to form a heating circuit by directly printing and forming an insulating film on the back surface of a mirror, and forming a heating circuit by printing and laminating a conductive film for electrodes on the insulating film. It is achieved by forming a layer of a non-solvent pressure-sensitive adhesive on, and providing a planar heating element covering the insulating protective film via the pressure-sensitive adhesive layer.

According to the above means, the respective films forming the planar heating element are sequentially laminated by printing without any trouble. Further, this printed laminated film is directly formed by printing on the back surface of the mirror without interposing an adhesive or the like, thereby improving the thermal conductivity to the mirror. In addition, the lowermost insulating film formed directly on the back surface of the mirror prevents leakage of the heater current flowing in the heating circuit of the conductive film for electrodes and the resistive film for heat generation thereover to improve heat generation efficiency, and particularly good thermal conductivity. When a film made of such an insulating material is used, it is possible to eliminate the unevenness of heat generation, at the same time enhance the thermal conductivity to the mirror, accelerate the temperature rise of the mirror, and perform uniform heating.

Further, the insulating protective film covering the heat generating circuit prevents the heat radiation to the outside of the heater and enhances the thermal efficiency. And
Since this protective film adheres via the adhesive layer, it is firmly connected to the heat generating circuit and can prevent glass from scattering when the mirror is broken.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments. FIG. 1 is a rear view of a mirror according to an embodiment of the present invention, FIG. 2 is a sectional view taken along AA, and FIG. 3 is a sectional view taken along BB. In the figure, 1 is a mirror and 2 is a planar heating element. Mirror 1
Is composed of a glass 1a and a reflective film 1b on the back surface.

The sheet heating element 2 is directly formed on the back surface of the mirror 1 by printing. As a first layer, an insulating film 21 is directly formed on the back surface of the mirror by printing, and a conductive film 22 for electrodes and a resistive film 23 for heat generation are printed and laminated thereon to form a heat generating circuit.
The insulating film 21 formed directly on the mirror 1 prevents the heater current from leaking to the reflective film (metal film such as Cr) of the mirror 1, and the insulating ink is used to form the mirror as shown in FIG. 6 (A). Printing is evenly printed on the heater portion on the back surface of No. 1. FIG. 6 shows an example of a screen printing pattern of each layer.

In the conductive film 22 for electrodes formed by printing on the printed insulating film 21, land portions 22a for soldering power supply lead wires or terminals and + and-electrodes are alternately opposed to each other in a comb shape. The comb-shaped portions 22b are arranged in such a manner that
As shown in FIG. 6B, it is printed with silver paste, copper paste, high conductivity carbon ink or the like.

The heat generating resistance film 23 to be printed next is made uniform by using carbon ink between the comb-shaped electrodes and on the electrode conductive film 22b, leaving the land portions 22a as shown in FIG. 6C. Printed and laminated to form a heating circuit. The order of stacking the electrode conductive film 22 and the heat generating resistance film 23 may be reversed.

An adhesive layer 24 is formed on the formed heating circuit. A non-solvent type pressure sensitive adhesive such as an aqueous pressure sensitive adhesive or a UV type pressure sensitive adhesive is used as the pressure sensitive adhesive. Examples of UV adhesives include photocurable resin TB3085 (ThreeBond Co., Ltd.), and water-based adhesives include TB1549 (ThreeBond Co., Ltd.). The former has good adhesiveness to various materials. It has a higher peel strength than that of the above adhesive and adheres well to difficult-to-adhere materials. The latter is a water-based pressure-sensitive adhesive containing acrylic emulsion as a main component for screen printing, and has excellent peeling adhesive strength and protective power.

The pressure-sensitive adhesive layer 24 is formed by printing or coating, but as shown in FIG. 6D, the pressure-sensitive adhesive layer 24 is uniformly coated with the land portions 22a of the conductive film 22 for electrodes remaining. In the case of a water-based pressure-sensitive adhesive, after printing or coating, it is dried to remove water and form a tacky film. Also, U
The V-type pressure-sensitive adhesive is a photo-curable resin, and after printing or coating, it is irradiated with ultraviolet rays to become a film having pressure-sensitive adhesiveness.

The pressure-sensitive adhesive layer 24 formed as described above
Via, a protective insulating film is printed or coated with an insulating ink, or an insulating film is attached thereto.
The insulating protective film 25 is also formed so as to cover the entire surface of the heat generating circuit, leaving the electrode land portion 22a as shown in FIG. 6D. The insulating materials shown in Table 1 are used as the overcoat material for insulation protection.

[0015]

[Table 1]

As described above, since the insulating protection film 25 covers the heat generating circuit with the adhesive layer 24 interposed therebetween, it is sufficiently firmly adhered to the heat generating resistance film 23 and the electrode conductive film 22 of the heat generating circuit,
Protect the surface.

FIG. 4 shows the appearance of the sheet heating element 2 formed by printing and laminating on the back surface of the mirror 1, and the heating resistor film 23, the adhesive layer 24 and the insulation protection formed on the electrode conductive film 22. In printing or coating the film 25, the conductive film 22 for electrodes is soldered to the exposed land portion 22a to connect the cord 3. An enlarged cross section of the soldering portion of the land portion 22a is shown in FIG. The core wire of the power cord 3 is soldered 51 to the electrode conductive film 22 in the land portion, and the silicone 52
Cover with insulation and waterproof protection.

By connecting the connector 4 at the tip of the cord 3 to a power source and supplying a heater current from the land portion 22a of the electrode conductive film 22 to the comb-shaped portion 22b, the heat-generating resistance film 23 interposed between the comb-shaped partial electrodes. Generates heat due to Joule heat. Since the insulating film 21 is interposed between the heater current and the mirror 1, leakage to the mirror 1 is prevented, heat generation efficiency is improved, and direct printing is performed between the heater and the mirror without using an adhesive or the like. Therefore, the heat conductivity of heat generation to the mirror 1 is excellent, and the temperature rise on the mirror surface can be accelerated.

If an insulating material having thermal conductivity is used for the insulating film 21, uneven heat generation in the heating circuit can be prevented,
The temperature rise of the mirror can be made uniform. TB2270 and the like shown in Table 1 are used as the heat conductive insulating material. Further, by using a material having a PTC characteristic for the heating resistance film 23, it is possible to automatically control the temperature by providing a self-temperature control function.

Since the pressure-sensitive adhesive layer 24 is formed on the heat generating circuit composed of the conductive film 22 for electrodes and the resistance film 23 for heat generation, and the insulating protective film 25 is covered via this, the insulating protective film 25 serves as a heat generating circuit. It adheres well and can prevent scattering when the mirror is broken. Further, by using a material having a large heat insulating property such as a foaming material for the protective film, it is possible to prevent the heat generated in the heat generating circuit from being radiated to the outside, enhance the heat efficiency of the heater, and thereby increase the temperature rise of the mirror surface.

[0021]

As described above, according to the present invention, since the insulating film is directly formed on the back surface of the mirror by printing, and the heat generating circuit of the conductive film for electrodes and the heat generating resistance film is printed and laminated thereon, the heater current Leakage is prevented, heat generation efficiency is improved, and heat conduction from the heat generation circuit to the mirror is excellent, and the temperature rise can be accelerated. In addition, when forming an insulating protective film for surface protection on the upper surface of the heating circuit, an adhesive layer is formed on the heating circuit,
Since the insulating protective film is covered with the pressure-sensitive adhesive layer, the adhesive strength is increased, and scattering when the mirror is broken can be prevented. In addition, the insulating protection film prevents current leakage to the outside due to its insulating properties, and also uses heat insulating properties to prevent the heat generated by the heater from being dissipated to the outside, increasing thermal efficiency and promoting the temperature rise on the mirror surface. To do.

Further, according to the present invention, by assembling the sheet heating element on the mirror by printing, the assembly process can be simplified and automated, and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

3 is a sectional view taken along line BB of FIG.

FIG. 4 is an external view of an embodiment of the present invention.

5 is a partially enlarged cross-sectional view of FIG.

FIG. 6 is a print pattern diagram of an embodiment of the present invention.

FIG. 7 is a structural diagram of a conventional example.

FIG. 8 is a sectional view of FIG.

FIG. 9 is a partially enlarged view of FIG. 8;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Mirror, 2 ... Sheet heating element, 21 ... Insulating film, 22 ... Electrode conductive film, 23 ... Heating resistive film, 24 ... Adhesive layer, 2
5 ... Insulating protective film, 3 ... Cord, 4 ... Connector.

Claims (1)

[Claims] 1. A rear-view mirror for a vehicle, wherein a planar heating element is provided on the rear surface of the mirror, and an insulating film directly printed on the rear surface of the mirror.
A heat generating circuit in which a conductive film for electrodes and a heat generating resistance film are printed and laminated on the insulating film, a layer of a non-solvent pressure sensitive adhesive formed on the heat generating circuit, and an insulating protective film covered through the pressure sensitive adhesive layer. A rear view mirror for a vehicle, which is provided with a planar heating element consisting of.