JPH08273415A - Light source with reflector - Google Patents

Abstract

PURPOSE: To suppress the occurrence of color lines, color stripes, brightness and darkness stripes, and the like by laminating high refractive index layers and low refractive index layers alternately on the surface of a reflector so as to constitute a light interference film, and thickening the film thickness thereof as the incident angle of the light from a light source becomes large. CONSTITUTION: High ref reactive index layers and low refractive index layers are alternately laminated on the inside surface of the curved base body 3 of a reflector so as to constitute a light interference film 4. In the light interference film 4, the film thickness thereof is made to be thick as the incident angle of the light from a light source 1 becomes large, that is, as approaching to the opening portion of the reflector. Thereby, the wavelength area of the penetrating-in or reflecting-on light becomes uniform on the whole surface of the light interference film 4 so that the occurrence of color lines, color stripes, and brightness and darkness stripes are suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light source with a reflecting mirror in which a reflecting mirror and a light source are integrally formed.

[0002]

2. Description of the Related Art Conventionally, halogen bulbs with a reflector have been used, for example, for store lighting. This type is composed of a small halogen bulb and a glass reflector having a paraboloid of revolution having a visible light reflecting and infrared transmitting film formed on the surface thereof. This visible-light-reflecting infrared-transmissive film is made of titanium oxide (Ti
A high refractive index layer made of O2) or the like and a low refractive index layer made of silica (SiO2) or the like, which are 9 to 15 layers alternately laminated,
Among the light emitted from the halogen bulb due to the interference of light, there is an advantage that the visible light wavelength range is reflected forward and the infrared wavelength range is transmitted backward so that the irradiated body is not damaged by heat.

The control of these wavelength ranges is related to the thicknesses of the high refractive index layer and the low refractive index layer, and is disclosed in Japanese Patent Publication No. 44-8
As disclosed in Japanese Laid-Open Patent Publication No. 272, it can be performed with a uniform thickness or a thickness having a controlled change over the entire surface of the reflecting mirror. A multilayer optical film that reflects or transmits light having a specific wavelength by utilizing light interference, such as the visible light reflection / infrared transmission film, is generically called an optical interference film.

[0004]

However, in the case of a light bulb arranged almost on the axis of a reflecting mirror of this kind, when the white illuminated surface is illuminated, if the illuminated surface is too close, There is a phenomenon that a ring of colored light is formed around the optical axis, and the irradiated object on which the ring of light hits appears to have a different color.

An object of the present invention is to provide a light source with a reflecting mirror in which it is difficult to form a ring of colored light around the optical axis of the illuminated surface.

[0006]

According to a first aspect of the present invention, there is provided a curved base body having a lamp mounting hole formed in a back portion thereof; the curved base body is optically opposed to the curved base body, and substantially on the axis of the base body. A light source arranged; and a high-refractive-index layer and a low-refractive-index layer alternately on the surface of the curved substrate, and optical interference configured such that the film thickness increases as the incident angle of light from the light source increases. A film; and a base directly or indirectly provided on the light source.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Regarding one embodiment of the present invention,
A halogen bulb with a reflector used for store lighting or the like will be described with reference to FIGS. 1 and 2.

FIG. 1 is a partially cutaway sectional view of a light source with a reflecting mirror showing an embodiment of the present invention, and FIG. 2 is an enlarged sectional view of the same main portion.

In the figure, 1 is a light source such as a halogen bulb, 2 is a base mounted on the base of the light source 1, and 3 is an inner surface surrounding the light source 1 mounted on the base 2 to form a paraboloid of revolution. Heat-resistant translucent curved substrate 4 made of glass or the like
Is an optical interference film formed on the inner surface of the substrate 3, for example, a visible light reflecting infrared transmitting film. The base is directly or indirectly provided on the light source or the base 3.

Here, the curved substrate 3 has an inner surface formed in a curved shape and a lamp mounting hole formed in the back portion. The light source 1 optically opposes the curved base body and is disposed substantially on the axis of the base body. Further, the light interference film 4 is configured such that high refractive index layers and low refractive index layers are alternately formed on the surface of the curved substrate 3 and the film thickness increases as the incident angle of light from the light source 1 increases. ing.

The optical interference film 4 has a high refractive index layer 41 made of titanium oxide or the like and a low refractive index layer 42 made of silica or the like on the surface of the substrate 3, as schematically shown in FIG. 20 to 26 layers are alternately laminated, and by appropriately adjusting the thickness of each layer 41, 42, visible light of the light incident from the light source 1 is reflected forward by the interference of light and infrared rays are reflected behind the substrate 3. It is transparent to.

In the present embodiment, the thicknesses of the high refractive index layer 41 and the low refractive index layer 42 forming the optical interference film 4 are adjusted so that the opening edge of the base 3 corresponds to the distribution of the incident angle from the light source 1. The thicker it gets closer to. That is, the optical interference film 4 including the high refractive index layer 41 and the low refractive index layer 42 formed on the base body 3.
Was made thicker as the incident angle θ of the light from the light source 1 becomes larger.

As a result, the visible light reflection wavelength range and the infrared transmission wavelength range are substantially uniform over the entire surface of the optical interference film 4, and the reflectance and the transmittance thereof are substantially the same as those at the low incident angle portion. . As a result, the visible light transmission efficiency of the light source with a reflecting mirror was significantly improved, and the infrared rays in the transmitted light were significantly reduced.

A theoretical explanation of the present invention will now be described in detail with reference to FIGS. 4 and 5. FIG. 4 is a schematic diagram for theoretically explaining the present invention, and FIG. 5 is an explanatory diagram similarly showing a change in incident angle.

As a result of various researches by the inventor of the present invention, as described above, a ring of colored light appears in the irradiation light from the light source with a reflecting mirror because the incident angle of the light from the light source is different. I reached the conclusion. In the figure, A is a light source, B is a refraction layer formed on a base member opposite to the light source A, the refraction layer B has a thickness of dmm and a refraction index of n. And the light source A
From the three light beams R1, R2, and R3 respectively enter at incident angles θ1 (0 degree), θ2 (small), and θ3 (large), pass through the inside of the refraction layer B, and are directed downward. At this time, if the incident angle θ is large, the same result will be obtained as the thickness of the layer is increased, even if the refractive layers have the same thickness, and the phase of the light at the emission point is shifted. Therefore, when the phase shift δ of the interference caused by the incident angle θ is obtained, it is expressed by the following equation.

Δ = 4πnd (cos θ) / λ where λ
Indicates the wavelength of light. That is, when the incident angle θ increases, the phase of interference shifts to the short wavelength side.

Therefore, in order to eliminate the phase shift due to the incident angle θ, the layer thickness d may be changed so that dcos θ becomes constant. In other words, in order to eliminate the phase shift due to the incident angle in the optical interference film, the thickness d of the layer is set corresponding to the incident angle θ so that dcos θ is constant in both the high refractive index layer and the low refractive index layer. You can change it.

As shown in FIG. 5, when the reflecting mirror (not shown) on which the light interference film I is formed has a parabolic surface and the light source A is located at the focal point, the light interference film I is formed. Since the incident angle θ at each portion becomes larger as it approaches the edge of the optical interference film I, the thickness of each layer may be increased as it approaches the edge so that dcos θ becomes as constant as possible.

Further, substantially the same is true when the optical interference film I formed along the curved surface of the reflecting mirror (not shown) is an elliptical surface or a hyperboloidal surface.

However, the above theory is approximate, and since the apparent refractive index of the refraction layer actually changes when the incident angle θ changes, it cannot be completely corrected, but there is no problem in practical use. It is easy to correct.

Various methods of forming such an optical interference film can be considered, but some examples will be described with reference to FIGS. 6 and 7. FIG. 6 is an explanatory diagram showing a method for forming the optical interference film, and FIG. 7 is an explanatory diagram showing another method for forming the same.

As shown in FIG. 6, an evaporator E is provided on the transparent substrate P1 so that the heat of the heater H is radiated from the rear surface of the substrate P1 by the reflecting mirror M so that the temperature becomes higher in the central portion and a vacuum is generated. By vapor deposition, a thicker refraction layer B can be obtained as it gets closer to the periphery. In this manner, for example, 15 to 20 high refractive index layers made of titanium oxide and 15 to 20 low refractive index layers made of silica may be alternately laminated. Although the plate-shaped transparent substrate P1 is shown in the figure, the curved refraction layer B is formed closer to the periphery even if it is curved.

Further, as shown in FIG. 7, the inner edge of the trapezoidal substrate P2 having a rotation parabolic surface and a lamp mounting hole Q, for example, a lamp mounting hole Q in the back, is provided at the opening edge of the organometallic compound solution L.
The lamp mounting hole Q with a suction port T to exhaust the liquid L to the vicinity of the mounting hole Q and then to the suction port T.
The gas is introduced at a controlled rate from the
Reduce the aspect of. By controlling the introduction rate of this gas, the thickness of the coating film on the inner surface of the substrate P2 can be controlled so that it becomes thicker as it approaches the opening edge as desired. Then, by baking the coating film thus obtained, a refraction layer made of a metal oxide and having a desired thickness distribution can be obtained. In this way, for example, a high refractive index layer made of titanium oxide and a low refractive index layer made of silica may be alternately laminated in an amount of 9 to 15 layers.

Next, in the present embodiment, the optical interference film 4
The change in spectral reflectance depending on the incident angle of was investigated. The result is shown in FIG. FIG. 3 is also a graph showing optical characteristics, in which the horizontal axis represents wavelength in nm and the vertical axis represents reflectance as a relative value. The solid line indicates an incident angle of 0 degrees and the chain line indicates incident light. The angle of 46 degrees and the broken line indicate the spectral reflectance at the site where the incident angle is 57.4 degrees.

FIG. 8 is a graph showing the optical characteristics of the conventional example. This is because in the same optical interference film as in the present embodiment, each refractive index layer is formed to have a uniform surface thickness, and the incident angles are 0 ° and 46 ° as described above. And the spectral reflectance at the site of 57.4 degrees were taken.
As is clear from these graphs, the optical interference film 4 of the present embodiment is very similar even in a region where the visible light transmission wavelength range and the infrared transmission wavelength range differ in incident angle.

Next, the characteristics of the light source with a reflecting mirror of this embodiment and the lamp characteristics of the conventional example were compared. The results are shown below. In the present embodiment, the luminous flux ratio, the central luminous intensity ratio, and the heat ray cut rate are 135%, 138%, and 79%, respectively, whereas in the conventional example, 100%, 100%, and 8%.
It became 2%.

As is apparent from the above, the light source with a reflecting mirror according to the present embodiment is significantly brighter than the conventional example, and the heat ray cut rate is not substantially reduced.

In the present invention, the shape of the reflecting base may be a curved surface such as a spheroid or a hyperboloid, and the reflecting base may be a diffuse translucent one.

Further, the light interference film may be a visible light transmitting infrared reflecting film, an interference color filter film or the like as long as it selectively transmits or reflects light in a specific wavelength range by utilizing the interference of light. It may be formed on at least one of the front and back surfaces. Further, the high refractive index layer may be any known one such as zircon oxide (ZnO2), tin oxide (SnO2), antimony oxide (SbO2) in addition to titanium oxide, and the low refractive index layer may be oxidized in addition to silica in addition to silica. Any known material such as magnesium (MgO) or calcium fluoride (CaF2) may be used. Further, the light source may be an ordinary light bulb, a metal halide lamp, a discharge lamp such as a fluorescent lamp, or the like.

[0030]

According to the present invention, the light source optically opposes the curved substrate and is disposed substantially on the axis of the substrate.
Since the optical interference film is configured such that high refractive index layers and low refractive index layers are alternately formed on the surface of the curved substrate and the film thickness increases as the incident angle of light from the light source increases.
The wavelength range that is transmitted or reflected is uniform over the entire surface of the optical interference film, and its reflectance or transmittance is also uniform,
Generation of color streaks, color stripes, bright and dark stripes, etc. can be suppressed.

[Brief description of drawings]

FIG. 1 is a partially cutaway cross-sectional view of a light source with a reflecting mirror showing an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of a main part of the same.

FIG. 3 is a graph similarly showing optical characteristics.

FIG. 4 is a schematic diagram for theoretical explanation of the present invention.

FIG. 5 is an explanatory view similarly showing a change in incident angle.

FIG. 6 is an explanatory view showing a method for forming an optical interference film.

FIG. 7 is an explanatory view showing another forming method similarly.

FIG. 8 is a graph showing optical characteristics of a conventional example.

[Explanation of symbols]

 1 ... Light source 2 ... Base 3 ... Curved substrate 4 ... Optical interference film

Claims (1)

[Claims] 1. A curved base having a lamp mounting hole formed in the back thereof; and being optically opposed to the curved base,
A light source disposed substantially on the axis of this substrate; high refractive index layers and low refractive index layers are alternately formed on the surface of the curved substrate, and the film thickness increases as the incident angle of light from the light source increases. A light source with a reflecting mirror, comprising: a light interference film configured as described above; and a base provided directly or indirectly on the light source.