JPS59214184A - Heater for defroster - 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 The present invention relates to a defroster heater that heats and removes frost or dew adhering to window glass or mirrors.

In this type of defroster heater, a conductive film with a predetermined resistance value is formed on a window glass or mirror as a substrate to form a heat-generating film, and by energizing this and generating heat, the board is heated and the frost that adheres to the board is removed. There are things that remove dirt and dew.

By the way, the heat-generating film described above not only heats the substrate in contact with it through thermal conduction, but also emits infrared rays, which are hot rays, and thereby radiantly heats the board. However, the infrared rays emitted from the heat-generating film surface on the side that does not face the substrate heat the substrate. The problem is that it dissipates without contributing much to the heating of the gas.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to provide a defroster heater that can prevent the dissipation of infrared rays emitted from a heat generating film and efficiently heat and remove frost and the like adhering to a substrate.

That is, in the defroster heater of the present invention, a conductive film having a predetermined resistance value is formed on the substrate surface, and this is connected to a power source to form a resistance heating film. The conductive film is formed by laminating films to form a Drude reflective film that reflects infrared rays emitted from the heat generating film toward the substrate.

Therefore, the infrared rays emitted from the heat-generating film are reflected toward the substrate by the reflective film, without being dissipated, and the substrate is efficiently heated, so that frost and the like adhering to the substrate are quickly removed by heat.

By the way, to explain the above-mentioned Drude reflection, a conductor or semiconductor having free electrons is in a solid plasma state and has a predetermined plasma frequency due to a change in the electron density of free electrons. Electromagnetic waves having a frequency lower than the plasma frequency are reflected without being incident on the conductor or the like.

Therefore, by appropriately selecting the electrical state of the conductive film constituting the Drude reflective film, it is possible to effectively reflect infrared rays.

The present invention will be explained below with reference to illustrated embodiments.

FIG. 1 shows an example in which the present invention is used to defrost the rear window of a vehicle. In the figure, a heat-generating film 2 is formed all over the side surface of the vehicle interior (top surface in the figure) of a window glass 1 of a rear window. The heat generating film 2 is made of indium oxide (In, O3
) is a so-called ITO film doped with tin oxide (SnO2), and has electrical conductivity, and its sheet resistance is approximately 10Ω.
It is set as low as /1. Electrodes 3a and 3b made of copper, nickel, aluminum, etc. are provided at the edge of the heat generating film 2, and current is supplied from a power source (not shown) through these electrodes, so that the heat generating film 2 generates resistance heat.

Note that the TO film is a transparent film through which visible light can pass.

Now, a reflective film 5 is laminated on the heat generating film 2 with an insulating film 4 interposed therebetween. The reflective film 5 is an ITO film like the heat generating film 2 described above. As will be described later, the electrical state of the reflective film 5 has been taken into consideration so that it can efficiently reflect infrared rays by Drude reflection while sufficiently transmitting visible light.

The insulating film 4 electrically insulates the heat generating film 2 and the reflection film 5, and in this embodiment, a magnesium fluoride film having a lower refractive index than the glass 1 is used. This M
The gF2 film is also a transparent film like the above-mentioned ITO film.

Here, in Fig. 2, the plasma energy of the reflective film 5 is 1-20 at 2.000V, and the relaxation energy E is 0.05c.
As V, the spectral reflectance of electromagnetic waves incident from the MgF2 layer was investigated. As can be seen from the figure, the reflective film 5 can very efficiently reflect electromagnetic waves in the infrared region with a wavelength of 1200 nm or more. In this case, visible light with a wavelength of 400 nm to 700 nm is transmitted without any problem.

Each of the films 2, 4, 5 J3 and the electrodes 3a, 3b are formed by vacuum evaporation, sputtering, or the like.

The operation of the defroster heater having the above structure will be explained below.

The heat-generating film 2 that is energized via the electrodes 3a and 3b generates heat,
It emits infrared rays from both sides. Infrared rays emitted from the surface in contact with the window glass 1 are converted into heat within the glass 1, and are efficiently heated.

On the other hand, infrared rays emitted from the side of the vehicle interior that does not face the glass 1 of the heating film 2 pass through the insulating film 4, and then most of it is reflected toward the glass 1 side by the reaction film 5, as shown in FIG. I am forced to do it. The reflected infrared rays are absorbed by the Mg constituting the insulating film 4.
The light is turned into an F2 film and is reflected again by the heat generating film 2 made of an ITO film with a high refractive index, and is thus converted into heat while being reflected within the insulating film 4. This heat is conducted to the reflective film 5 and the heat generating film 2 that are in contact with the insulating film 4, and is further conducted from the heat generating film 2 to the glass 1 to heat it.

Note that in this example, MgF2 constituting the insulating film 4
Since the refractive index of the film is smaller than that of the glass 1, the difference in refractive index between the heat generating film 2 and the insulating film 4 is greater than that between the heat generating film 2 and the glass 1. The energy reflectance of electromagnetic waves at the interface of materials increases as the difference in refractive index between the two materials forming the interface increases, so the energy reflectance of infrared rays increases at the interface between the heat generating film 2 and the insulating film 4, and therefore the heat generation increases. Much of the infrared rays emitted from the film 2 are emitted in the direction of the glass 1, which also heats the glass 1 efficiently.As a result of the glass 1 being heated as described above, the outer surface of the glass 1 (lower surface in FIG. Frost that adheres to the surface is rapidly melted and removed.

FIG. 3 shows the amount of temperature rise of the glass 1 near 0° C. by the heater of the present invention. Lines X and V in the diagram. Z is the power density input to the heat generating film 2, which is 0.13w/am.
”. This shows the amount of temperature rise when 0.19W/cm2 and 0.2gW7crnl2 are used. According to this figure, the temperature rise reaches 10℃ to 20℃ in about 2 minutes, and the frost that adheres to the glass surface is rapidly removed. will be removed.

Furthermore, although the surface of the reflective film 5 facing the vehicle interior sometimes forms dew condensation and becomes cloudy, this is quickly eliminated by the heat conducted from the insulating film 4.

In addition to the above-mentioned effects, the heater of the present invention uses a transparent film as a heating element and is formed on the entire glass surface. The frost located between the two may remain unmelted,
Alternatively, there is no problem that the heating element after the disconnection point becomes useless due to the disconnection, and the frost adhering to the glass surface is effectively removed.

In addition to MfF2, the insulating film 4 can be made of a material that is transparent and has a refractive index lower than that of the glass 1, such as cerium fluoride <CeF3.

In addition, in the above embodiment, the heater was formed on the side surface of the vehicle interior of the window glass, but it may also be formed on the outside surface of the vehicle.In this case, the order in which each film is stacked is as in the above embodiment, starting with the heat-generating film and the insulating film from the side that is in contact with the glass surface. Film, then reflective film.

As described above, the defroster heater of the present invention has a heat generating film made of a transparent conductive film formed on the entire surface of the window glass, and a transparent conductive film serving as an infrared reflective film is laminated on the heat generating film via a transparent insulating film. By doing so, it is possible to ensure the transmission of visible light and prevent the dissipation of infrared rays emitted from the heat generating film, thereby efficiently heating the glass and quickly eliminating frost and dew adhering to the glass surface.

In the above embodiment, the positions where the electrodes are provided are as shown in Figures 4 and 5.
The position shown in the figure may also be used.

That is, in FIG. 4, the electrodes 3a and 3b are connected to the heat generating film 2.
, and then formed on the upper surface thereof. According to this, unlike the case of the above embodiment in which the electrodes 3a and 3b are formed before the heat generating film 2, the electrodes 3a and 3b are not oxidized by oxygen mixed into the atmosphere when the heat generating film 2 is formed.

FIG. 5 shows electrodes 3a, 3b on the upper and lower surfaces of the heat generating film 2, respectively.
3c and 3d are formed. As a result, electrode 3
The contact area between a, 3b, 3c, and 3d and the heat generating film 2 is increased, and contact resistance can be kept small.

FIG. 6 shows another embodiment, in which the heater of the present invention is used to defrost a fender mirror or the like of a vehicle. That is, a metal film 6 made of aluminum, chromium, titanium, or an alloy thereof, which has a very high visible light reflectance, is formed on one surface of the glass substrate 1 to constitute a mirror. On the other surface of the substrate 1 onto which external light is incident, a heater is formed by laminating a transparent heat generating film 2, an insulating film 4, and a reflective film 5 similar to those in the above embodiment.

Frost adhering to the surface of the reflective film 5 (top surface in the figure) is rapidly melted and removed by heat conduction from the heat generating film 2 as well as from the insulating film 4 and substrate 1 heated by the radiated infrared rays. Ru.

Note that if the incident side of external light is the lower side of the figure, the substrate 1 and the films 2, 4, and 5 do not need to be transparent; resin or ceramic can be used as the substrate 1, and the heat-generating film 2 and As the reflective film 5, a metal film such as chromium or aluminum can be used, and as the insulating film 4, a titanium nitride film or the like can be used.

As described above, in the defroster heater of the present invention, a conductive film having a predetermined resistance value is formed on the surface of a substrate to form a resistance heating film, and a conductive film is further laminated on the heating film with an insulating film interposed therebetween. By using the conductive film as a Drude reflective film that reflects infrared rays emitted from the heat generating film toward the substrate, and effectively preventing the dissipation of infrared rays, frost or dew attached to the substrate can be quickly removed by heating. That is.

[Brief explanation of drawings]

1 to 3 show an embodiment of the present invention,
Figure 1 is a cross-sectional view of a rear window of a vehicle on which a heater is formed, Figure 2 is a diagram showing the spectral reflectance of the reflective film, Figure 3 is a diagram showing the temperature rise of the glass on which the heater is formed, Figure 4, FIG. 5 is a cross-sectional view showing the formation positions of electrodes, and FIG. 6 is a cross-sectional view of a mirror portion of a fender mirror in which a heater is formed, showing another embodiment of the present invention. 1... Substrate 2... Heat generating films 3a, 3b... Electrodes 4... Evergreen film 5... Reflective film 6...・・・Metal membrane agent Ben-bu Jui Uegiuma

Claims (3)

[Claims] (1) A conductive film having a predetermined resistance value is formed on the substrate surface, and this is connected to a power source to form a resistance heating film, and a conductive film is further laminated on the heating film via an insulating film, A heater for a defroster, characterized in that the conductive film is a Drude reflective film that reflects infrared rays emitted from the heat generating film toward the substrate. (2) The defroster heater according to claim 1, wherein the difference in refractive index between the insulating film and the heat generating film is greater than the difference in refractive index between the substrate and the heat generating film. (3) The substrate is a window glass or a mirror, and the heat generating film, the insulating film, and the reflective film are made of a transparent material, and these are laminated on the front or back surface of the window glass or mirror, according to claim 1. Defroster heater.