JPH07156758A - Mirror with heater - Google Patents

Abstract

PURPOSE:To provide a mirror with a heater which has the durability and appropriate reflection factor, and rapidly remove water drop, ice or the like attached to the surface by forming a heating resistor and reflective film of titanium. CONSTITUTION:A reflective film 2 consisting of a heating resistor is formed on the rear surface of a mirror base plate 1. This reflective film 2 is a titanium film formed by the spattering method or the vacuum deposition method. In addition, a pair of opposite electrodes 3a, 3b to energize the reflective film 2 which is also the heating resistor are provided on the rear surface of the reflective film 2. The space between these electrodes 3a, 3b in the vicinity of the end part of the mirror base body 1 is narrower than the space between the electrodes at the center part so that the uniform heating may be realized over the whole area of the mirror. In addition, the rear surface of the mirror is coated for the purpose of the electrical insulation by an insulating layer 4 of resin, rubber, etc., with small Young's modulus where no cracks are generated by the temperature change.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is for use in bathroom mirrors, vehicle door mirrors, etc., and is equipped with a heater for anti-fogging or removing water drops, raindrops, dew, ice, etc. adhering to the mirror surface. Regarding the mirror.

[0002]

2. Description of the Related Art When a vehicle travels during rain or snow in a cold region, water drops adhere to the rear-view mirrors or freeze up, and the rear visibility is insufficient and the driving safety is impaired. In order to prevent the above, various mirrors that can be heated to remove water droplets, ice, etc. adhering to the mirror surface by heating have been proposed.

Among them, in Japanese Utility Model Laid-Open No. 5-13872, in order to quickly remove water droplets, ice and the like adhering to the mirror surface, chromium or nichrome is reflected on the surface of the mirror substrate by vacuum vapor deposition or sputtering. A mirror with a heater formed as a film and a heating resistor has been proposed.

[0004]

Generally, in a mirror with a heater for a vehicle, it is preferable that the current to be heated is about 1 to 5 amperes. This is because if the current is too small, it is inferior in the deicing performance especially when exposed to the wind during cold weather, and if it is too large, it is overheated by the overshoot during energization by the temperature control function, This is because it may cause burnout including peripheral parts and human burns. Therefore, in the case of a vehicle, considering that a DC voltage of 12 V is applied to the mirror with a heater, the sheet resistance of the reflecting film and the heating resistor of the mirror is the mirror shape (for example, the ratio of the length and width).
Considering the above, in order to enable uniform heating, 4-20Ω
The range of / □ is preferable.

However, in the above mirror with heater, the one using chrome as a reflecting film and a heating resistor is as follows.
Since its specific resistance is low, it is necessary to make the film thickness as thin as possible in order to obtain an appropriate resistance value. Specifically, the film thickness is 0.03
It must be less than or equal to μm. However, with such a thin film, even though it is a metal film, the transmission of light cannot be ignored, and it becomes a half mirror rather than a reflecting mirror, so the back side can be seen through depending on how light hits and it is difficult to use. There is.

On the other hand, when nichrome having a relatively high specific resistance is used as a reflecting film and a heating resistor, there is a problem that the adhesiveness between the nichrome and the electrode is low and stable performance is difficult to obtain.

When chromium silicide having a higher specific resistance is used, the film thickness is required to be at least about 1 μm in order to obtain a desired heating current. However, stress may cause cracks in the film itself or heating may occur. At times, there is the inconvenience of breaking the glass plate that is the mirror substrate. This inconvenience is particularly remarkable in the convex mirror in which bending stress remains on the mirror substrate.

Among various metal silicides, titanium silicide has a suitable specific resistance, but the metal silicide, including the above-mentioned chromium silicide, has a low reflectance of 40% or less. Poor performance and practically unusable.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and a reflective film made of a heating resistor on a substrate and an electrode for heating the reflective film with electricity. In the mirror with a heater provided with, the gist of the mirror with a heater is characterized in that the heating resistor / reflection film is made of titanium.

[0010]

Embodiments of the present invention will be described in detail with reference to the drawings. 1 is a schematic rear perspective view of a heater-equipped mirror used in a vehicle door mirror that is an embodiment of the present invention.
Is a schematic view of a vertical section thereof. Reference numeral 1 is a mirror substrate, which is made of a transparent material such as glass. A reflective film 2 made of a heating resistor is formed on the back surface of the mirror substrate 1.

In the present invention, the reflective film 2 needs to be a titanium film formed by a sputtering method or a vacuum evaporation method. However, the titanium film mentioned here is formed by a sputtering method or a vacuum evaporation method, and therefore includes a titanium film containing a slight amount of impurities depending on the manufacturing conditions and apparatus. As impurities, oxygen,
There are such things as nitrogen and carbon, and the content of oxygen is ~
10 atomic%, nitrogen-1 atomic%, and carbon-5 atomic%. The thickness of the titanium film varies depending on the shape of the mirror, but is preferably 0.05 to 0.15 μm.

Further, on the back surface of the reflection film 2, a pair of electrodes 3a and 3b facing each other for energizing the reflection film 2 which is also the heating resistor is provided. The opposing electrodes 3a and 3b are provided such that the distance between the electrodes in the vicinity of the ends of the mirror substrate 1 is smaller than the distance between the electrodes in the center so that uniform heating can be performed over the entire surface of the mirror. There is. The electrodes 3a and 3b can be formed by various methods. For example, a thin copper layer is formed using a copper paste, solder is applied on the thin layer, or a thin nickel layer is formed by nickel plating. Further, the rear surface of the mirror is coated with an insulating layer 4 of resin, rubber or the like having a low Young's modulus which does not cause cracks due to temperature change, for electrical insulation. Reference numeral 5 is a lead wire for connecting the electrode 3 and a power supply circuit (not shown).

As a specific example, a titanium film having a thickness of 0.1 μm was formed on a glass substrate by a sputtering method to serve as a heating resistor / reflection film, and a mirror with a heater was produced as described above. This mirror with heater has a direct current of 12
When a voltage of volt was applied, a current of 4 amps flowed. When the heating of the mirror with heater was controlled by a temperature control circuit using a thermistor as a temperature detector or a thermostat, the temperature of the mirror surface could be controlled as set within a range of 50 to 60 ° C. Further, the reflectance of this mirror is 45 to 50%, which is slightly lower than that of the conventional chrome reflective film, but it can be used as a mirror without any problems, and the rear of the mirror cannot be seen through depending on how the light hits. Furthermore, there was no inconvenience that cracks were generated in the film itself due to stress or that the glass plate serving as the mirror substrate was broken during heating.

[0014]

The mirror with a heater according to the present invention is excellent in durability, has an appropriate reflectance, and can be heated by an appropriate electric current, so that a desired temperature control can be performed.
This is a practically excellent one that can quickly remove water drops, ice, etc. adhering to the surface while maintaining the original function of the mirror.

[Brief description of drawings]

FIG. 1 is a schematic rear perspective view of an embodiment of the present invention.

FIG. 2 is a schematic vertical sectional view of FIG.

[Explanation of symbols]

 1 mirror substrate 2 reflective film 3a electrode 3b electrode 4 insulating layer 5 lead wire

Claims (1)

[Claims] 1. A mirror with a heater, wherein a reflective film made of a heating resistor and an electrode for heating by heating the reflective film are provided on a substrate, wherein the heating resistor / reflecting film is made of titanium. A mirror with a heater.