JPH01109660A - Incandescent lamp with infrared-ray reflecting filter - Google Patents

Abstract

PURPOSE:To improve the radiation efficiency of visible rays and prevent the breakdown of an infrared-ray reflecting filter due to the damage from the outside by specifying the optical thickness of a thin film on the outermost layer. CONSTITUTION:The optical thickness of a thin film 5 on the outermost layer is set to 410-510nm or 780-910nm in an incandescent lamp 1 with an infrared- ray reflecting filter. Since the optical thickness of the thin film on the outermost layer is formed relatively thick within the range to offer a low reflection coefficient for visible rays, the radiation efficiency of visible rays is high. When a damage from the outside is inflicted, the damage rarely penetrates the thin film on the outermost layer and reaches a thin film on the inside, thereby the breakdown of the infrared-ray reflecting filter 6 due to the damage from the outside can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an incandescent light bulb with an infrared reflective filter.

[Conventional technology and problems]

Conventionally, in incandescent light bulbs such as halogen light bulbs that have a filament inside the bulb, the light emitted by heating the filament has the spectral characteristics shown in Figure 3, and most of it is infrared. Visible light accounts for only about 15% of light, and human visibility to light is at its maximum at a wavelength of about 555 nm, but as it shifts from this wavelength to shorter or longer wavelengths, it rapidly decreases. has declined to For this reason, the proportion of visible light to the total radiation emitted from the filament of an incandescent light bulb is extremely low.

On the other hand, in order to improve the radiation efficiency, there is a method of forming an infrared reflective filter on the outer surface of the bulb of the incandescent light bulb. This infrared reflection filter is constructed by laminating TIE films with different refractive indexes, and due to the interference effect of these laminated thin films, visible light from the filament is transmitted and infrared light is reflected. The infrared light reflected by the infrared reflective filter further heats the filament, increasing the temperature of the filament and increasing the emitted light. With the same electrical input, the emitted light is increased without increasing the electrical input of the device, resulting in a high radiation efficiency.

However, in an incandescent light bulb with an infrared reflection filter, the infrared reflection filter applies a thin film made of materials with different refractive indexes to the outer surface of the incandescent bulb. The transmittance of visible light is increased by alternately laminating layers with a thickness selected so that the product of Depending on the usage conditions of the incandescent lamp, the infrared reflective filter may be easily damaged from the outside. Therefore, if the outermost thin film is relatively thin, the outermost layer may be damaged due to the external damage. The thin film inside the thin film may also be damaged, and the infrared reflective filter may be destroyed.

Further, such an infrared reflection filter has a reflectance of about 25 to 37%, and the ratio of the irradiation to the filament becomes even smaller, resulting in a decrease in radiation efficiency.

[Purpose of the invention]

In view of the above points, the present invention has high radiation efficiency of visible light,
Moreover, it is an object of the present invention to provide an incandescent light bulb with an infrared reflective filter that is less susceptible to external damage.

[Means and actions for solving the problem] The above purpose is:
According to the present invention, thin films made of materials with different refractive indexes are alternately laminated on the outer surface of the bulb of an incandescent light bulb with film thicknesses selected so that the optical film thicknesses are equal, and a low refractive In an incandescent lamp with an infrared reflective filter formed by laminating an outermost thin film made of a material of This is achieved by being

According to this invention, the optical thickness of the outermost thin film is formed relatively thick within a range that provides a low reflectance for visible light, so that visible light radiation efficiency is high and damage from the outside is high. Even if the infrared reflective filter is damaged, the damage rarely penetrates the outermost thin film and reaches the inner thin film, and therefore the infrared reflective filter is less likely to be damaged by external damage.

〔Example〕

The present invention will be described below based on embodiments shown in the drawings.

FIG. 1 shows an embodiment of an incandescent light bulb with an infrared reflective filter according to the present invention. This incandescent light bulb 1 with an infrared reflection filter has a Ti0 light bulb 2 with a refractive index of 2.25 on the surface of a bulb 2 made of glass with a refractive index of 1.48.
tf) The thin film 3 and the SiJ thin film 4 having a refractive index of 1.45 are heated to a thickness of, for example, 260 rom so that their optical thicknesses (the product of the actual film thickness and the refractive index) are equal. They are alternately laminated with a predetermined film thickness selected to have an optical film thickness, and then a Sin film is deposited on top of the film.

An infrared reflection filter 6 of four to eight layers is formed by laminating the outermost thin film 5 consisting of the following.

Here, in the case where a four-layer infrared reflection filter 6 is formed, the reflection efficiency of the infrared reflection filter 6 for the total emitted light and visible light from the filament of the incandescent light bulb l with respect to the thickness of the outermost thin film 5 is as follows: This will be explained with reference to the graph in FIG.

As indicated by the symbol R1, it can be seen that the reflectance for all emitted light does not vary much, but the reflectance for visible light R2 varies periodically. That is, R2 ranges from 85 to 1 with a peak at about 120r+n+, which is the thickness of the outermost thin film 5.
45 rom, a range of 410 to 4B0na+ with a peak of about 442 nm, and a range of 780 to 860 rom with a peak of about 822 ns. The radiation efficiency of the incandescent lamp 1 improves as the reflectance R1 increases and as the reflectance R2 decreases, so that a high radiation efficiency of the incandescent lamp 1 can be obtained within the above range.

Thus, the thickness of the outermost thin film 5 can be appropriately selected within the above range depending on various conditions, for example, the possibility of external damage. In particular, in the range where the thickness of the outermost thin film 5 is in the range of 410 to 480 nm and in the range of 780 to 860 nm, the thickness of the outermost thin film 5 is sufficiently large, so that the outermost thin film 5 may be damaged by external damage. Damage does not penetrate through 5 to the thin film inside it.

In addition, when the eight-layer infrared reflection filter 6 is formed on the outer surface of the bulb of the incandescent light bulb 1, similarly, when the thickness of the outermost thin film 5 is in the range of 440 to 510 ns and in the range of 780 to 910 nm, High radiation efficiency of the incandescent light bulb 1 can be obtained, and since the thickness of the outermost thin film 5 is sufficiently large, damage from the outside can penetrate through the outermost thin film 5 and cause damage to the inside of the outermost thin film 5. It never reaches the thin film.

〔Effect of the invention〕

As described above, according to the present invention, thin films made of materials with different refractive indexes are alternately laminated on the outer surface of the bulb of an incandescent light bulb with film thicknesses selected so that the optical film thicknesses are equal. In an incandescent light bulb with an infrared reflective filter, in which an infrared reflective filter is formed by laminating an outermost thin film made of a material with a low refractive index thereon, the optical thickness of the outermost thin film is 410 to 510 nm. or 7
80 to 910 nm, the optical thickness of the outermost thin film is relatively thick within a range that provides a low reflectance for visible light. The radiation efficiency is high, and even if it is damaged from the outside, the damage rarely penetrates the outermost thin film and reaches the inner thin film. Therefore, due to external damage, infrared radiation Reflection filters are less likely to be damaged.

Thus, according to the present invention, it is possible to provide an extremely excellent incandescent lamp with an infrared reflection filter, which has high radiation efficiency and is not susceptible to external damage, and is optimal for use in automobiles and general lighting.

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view showing a part of the bulb surface of an embodiment of an incandescent light bulb with an infrared reflection filter according to the present invention;
The figure is a graph showing the relationship between the optical thickness of the outermost thin film and its reflectance in the embodiment of FIG. 1. FIG. 3 is a graph showing the spectral characteristics of emitted light from the filament of a conventional incandescent light bulb. 1.--Incandescent light bulb with infrared reflective filter; 2.--
...-bulb; 3--Ti (h thin film; 4--
SiO□ thin film: 5...--Outermost layer thin film; 6...
---Infrared reflection filter: R1 ---Reflectance for total emitted light, R2 ---Reflectance for visible light. Patent applicant: Stanley Electric Co., Ltd. Representative: Patent attorney Ken Hirayama

Claims (1)

[Claims] On the outer surface of the bulb of an incandescent light bulb, thin films made of materials with different refractive indexes are alternately laminated with film thicknesses selected so that the optical film thicknesses are equal, and then a thin film made of a material with a low refractive index is layered on top of the thin films made of materials with different refractive indexes. An incandescent light bulb with an infrared reflective filter, in which an infrared reflective filter is formed by laminating outer thin films, and the optical thickness of the outermost thin film is 410 to 510 nm or 780 to 910 nm. An incandescent light bulb with an infrared reflective filter, characterized in that it is selected as follows.