JPH03214503A - White illumination device - Google Patents

Abstract

PURPOSE:To accomplish a white illuminating device small in the overall structure and prevent noise inclusion into peripheral electric equipment by furnishing a specific reflex film on the surface of a reflex board which reflects the light from an incandescent electric bulb into the specified direction. CONSTITUTION:A white illuminating device is composed of a reflex board 4 for reflecting the light from an incandescent lamp 3 into a specified direction and a reflex film 5 formed over the surface of this reflex board 4. The reflex board 4 uses a sheet material excellent in reflex characteristic such as Al and Ag and assumes a hemispherical form in order to cast the light of incandescent lamp 3 reflected by the reflex film 5 into the specified direction. The reflex film 5 is made of for ex. film form dielectric substance (MgF2, SiO2, CeF3, etc.), in which the energy reflection ratio maximizes in three wavelength ranges, i.e. blue, green, and red, so that a high efficiency white light with minor energy loss is obtained through reflecting of the light of incandescent lamp 3 at the reflex film 5. This enables embodying in small construction, lowering of the drive voltage, and prevention of noise inclusion into peripheral electric equipment.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a white lighting device used, for example, as lighting for a liquid crystal color graphic display.

[Conventional technology and its issues] Traditionally, lighting devices for liquid crystal graphic displays have generally used a three-wavelength light source as a light source in view of color rendering properties and color reproducibility associated with the colorization of liquid crystal display panels. Fluorescent lamps are used.

However, the three-wavelength fluorescent lamp itself is expensive and requires peripheral circuits such as a power supply and heater, which increases costs and increases the size of the entire device. Ta.

In addition, there is also the problem that the driving voltage is high, which causes adverse effects such as noise on peripheral electrical equipment.

The present invention has been made based on the above-mentioned circumstances, and its purpose is to provide a white lighting device that reduces cost and size, and prevents noise from being caused to peripheral electrical equipment. [Means for Solving the Problems] In order to achieve the above object, the present invention includes an incandescent light bulb, a reflector for reflecting the light of the incandescent light bulb in a predetermined direction,
is formed on the surface of the reflector and has high reflectance in the blue wavelength range, green wavelength range, and red wavelength range,
The technical means includes a reflective film that reflects the light from the incandescent bulb as white light having a high color temperature and excellent color rendering properties. [Function] The present invention having the above configuration has a reflective film having high reflectance in the three wavelength ranges of blue, green, and red formed on the surface of the reflector plate, so that the light from the incandescent bulb is reflected by the reflective film. When doing so, it is possible to obtain reflected light having high spectral energy only in the above three wavelength bands in the wavelength band of an incandescent light bulb.

In other words, by using a reflective film that has high reflectance in the three wavelength regions of blue, green, and red, which enables white lighting with high color temperature and excellent color rendering, energy loss from incandescent light bulbs can be reduced. Obtains low white light. [Effects of the Invention] The present invention, which has the above-mentioned effects, can provide white illumination similar to that of a three-wavelength fluorescent lamp by reflecting the light from an incandescent bulb on a reflective film. Therefore, the driving voltage is low,
Also, power supply equipment, heaters, etc. By using incandescent light bulbs, which do not require peripheral circuits, it is possible to reduce costs, downsize the entire device, and prevent noise from surrounding electrical equipment. [Example] Next, a white lighting device of the present invention will be explained based on an example shown in the drawings. Figure 1 is an overall schematic diagram of the white lighting device. The white lighting device 1 of this embodiment is applied as a light source for illuminating a liquid crystal display panel (not shown) used in a vehicle instrument panel, etc.
It consists of an incandescent light bulb 3 powered by an onboard battery 2, a reflector 4 for reflecting the light from the incandescent bulb 3 in a predetermined direction, and a reflective film 5 formed on the surface of the reflector 4. .

As the incandescent light bulb 3, it is possible to use a light bulb that uses a filament such as a tungsten wire as a light emitter, or a halogen light bulb that has a small heat-resistant bulb filled with an inert gas and a small amount of halogen material. The reflective plate 4 is made of a thin plate material with excellent reflective properties, such as aluminum or silver with a thickness of IGOOA, for example, and in order to irradiate the light from the incandescent bulb 3 reflected by the reflective film 5 in a predetermined direction,
As shown in Figure 1, it has a hemispherical shape. The reflective film 5 is made of a thin film dielectric (MgF2, Sift, CeFi, etc.) with a thickness of iooo to 3000 Å, for example, and is formed on the surface (concave curved surface side) of the reflective plate 4 by vapor deposition, sputtering, etc. (Figure 1 shows a two-layer state).Here, the reflective film 5 will be described in detail.Assuming that the thickness of the reflective film 5 is d, the refractive index is n, and the wavelength of the color of light constituting white is λ, The energy reflectance of the reflective film 5 is
It is maximum when expressed by the following formula. nXd=2mXλ/4
(m: integer) The wavelengths λ of the colors of light that make up white are: Blue: 400ns, Green = 500nl, Red: 600nl
m, so if a thin film dielectric with nXd = 175 x 10-' is selected, the energy reflectance can be maximized in the three wavelength regions of blue, green, and red mentioned above, as shown in Figure 2. ．． Therefore, for example, by reflecting the light from the incandescent bulb 3 having the spectral energy distribution shown in FIG. 3 on the above-mentioned reflective film 5, highly efficient white light with small energy loss can be produced as shown in FIG. Obtainable. In this way, the incandescent bulb 3 can be used to provide white illumination with a spectral energy distribution similar to that of a three-wavelength fluorescent lamp, so compared to the conventional case using a fluorescent lamp, In addition to being able to reduce costs, it is also possible to downsize the entire device.Furthermore, since the drive voltage can be lowered, noise to peripheral electrical equipment can be prevented.In addition, in this example As shown in the above, by making the reflective film 5 multi-layered, the reflectance can be further improved and the efficiency can be made higher.However, it is not always necessary to make the reflective film 5 multi-layered; It may be.

[Brief explanation of drawings]

1 to 4 show an embodiment of the present invention,
Figure 1 is a white lighting system! Figure 2 is a graph showing the reflectance characteristics of the reflective film, Figure 3 is a graph showing the spectral energy distribution of an incandescent light bulb, and Figure 4 is a graph showing the spectral energy distribution of an incandescent light bulb. This is a graph showing the spectral energy distribution of reflected light. In the diagram

Claims (1)

[Scope of Claims] 1) (a) an incandescent light bulb; (b) a reflector for reflecting the light of the incandescent bulb in a predetermined direction; and (c) a blue color formed on the surface of the reflector. a reflective film that has high reflectance in the wavelength range of , the green wavelength range, and the red wavelength range, and reflects the light from the incandescent bulb as white light with high color temperature and excellent color rendering properties. A white lighting device.