GB2229264A - Lighting fixture - Google Patents

Abstract

A lighting fixture comprises a halogen lamp (6) of the single end metal type operable at a voltage of 12 V to emit rays of light, and a reflecting member (5) disposed in opposition to the halogen lamp and reflecting the rays of light emanating from the halogen lamp. The reflecting member contains a reflecting substrate, an optical multi-layer film, and a light absorbing layer formed therebetween. The optical multi-layer film reflects the visible rays of light contained in the light emanating from the halogen lamp to increase the color temperature of the light emanating from the halogen lamp up to 4000 K and reflects the light at 4000 K of color temperature. <IMAGE>

Description

"LIGHTING FIXTURE" The present invention relates to a lighting fixture, such as a spot light to emit a light of a different color from the light of a lamp, used in an illumination installation in a shop, for example.

Of the lighting fixtures of this type, some lighting fixtures have the lifetime of 100 to 500 hours and the color rendering index (Ra) of 90. In the spot light, a discharge lamp of high brightness whose color rendering index is between 60 and 84 is used for a light source.

There is known such a spot light that includes a halogen lamp or a light source operating at 100 V of a commercial power supply, and a reflecting member with an optical multi-layer formed thereover, which is disposed in opposition to the halogen lamp. The reflector member receives a color light from the light source, and reflects or projects the rays of light whose color is different from that of the incident light.

When the conventional spot light using the discharge lamp is used for the short distance illumination, many problems arise a range of illumination is broad, and the illumination is too high. It is very difficult to illuminate all the objects. Further, the illumination installation per se becomes large and expensive.

In the case of the spot light using a halogen lamp of 100 V of the commercial voltage, to render the colored light whity, the color temperature must be increased up to 4000 K. When the color temperature is increased up to this figure by forming an optical multi-layer formed on the surface of the reflecting member, the efficiency of utilization is reduced. When the color temperature of the light emitted from the halogen lamp (whose color temperature ranges from 2700 K to 2900 K) of 100 V is increased to 4000 K, the efficiency of utilization of the halogen lamp is about 50%, as shown in Figs. 1 and 2. When the colored light of the halogen lamp whose colored light is at 2700 K of color temperature, is increased in color temperature at about 60% of the efficiency of utilization, the increased colored temperature is approximately 3400 K to 3500 K at the highest.Such an increase of color temperature cannot provide a sufficient whity feeling.

As shown in Fig. 3, for a halogen lamp of 100 whose color temperature is 2800 K, and lifetime is 2000 hours, to increase the color temperature up to 3000 K, the color temperature must be increased by 107%, and the voltage must be increased by 115%, viz., up to 115 V.

In this case, the lifetime of the lamp is 20%, i.e., 400 hours.

Alternately another lighting fixture is known in which a light emitted from a halogen lamp is reflected by a reflecting member of an optical multi-layer film mounted on a transparent substrate such as a glass plate to project a color light from the device. In the device, some rays which are not reflected by the optical multi-layer film transparents the glass plate to irradiate the circumferential members such as a ceiling.

Such an illumination is not desirable to cause the circumferential atmosphere to be worse.

Accordingly, one object of the present invention is to provide a lighting fixture which can easily provide a white light of 4000 K by using a halogen lamp of low voltage, i.e., lower than 100 v, provide an illumination of excellent whity feeling without remarkable reduction of lifetime, with small size and low cost to manufacture.

The other object of the present invention is to provide a lighting fixture which may prevent undesirable rays to be leaked from the reflecting member.

In an aspect of the present invention there is provided a lighting fixture comprising: a halogen lamp of the single end metal type operable at a voltage lower than 100 V to emit rays of light; and a reflecting member disposed in opposition to the halogen lamp and reflecting the rays of light emanating from the halogen lamp, the reflecting member containing an optical multi-layer film which reflects the visible rays of light contained in the light emanating from the halogen lamp to increase the color temperature of the reflecting light to be higher than that of the light emanating from the halogen lamp.

In the other aspect of the present invention there is provided a lighting fixture comprising: a light source for emitting a light including a component of a predetermined color; a reflecting member disposed in opposition to the light source, including a reflector having a relatively high reflection factor, an optical multi-layer film for reflecting the light component of a predetermined color in the light emitted from the light source, and light absorbing film provided between the reflector and the optical multi-layer film.

This invention can be more fully understood from the following detailed description when taken in conjunction with the accompanying drawings, in which: Fig. 1 is a graph showing an efficiency of utilization vs. change of each color temperature of an ordinary halogen lamp; Fig. 2 is a graph of a color temperature vs.

efficiency of utilization in which the color temperature of 2700 K is increased up to 3600 K; Fig. 3 is graph of a relationship between a lifetime vs. voltage; Fig. 4 is a partially broken side view of a lighting fixture according to an embodiment of the present invention; Fig. 5 is a cross sectional view of a part of a reflecting member used in the lighting fixture of Fig. 4; Fig. 6 is a cross sectional view of a part of a modified reflecting member; Fig. 7 is a graph of a relationship of reflectivity vs. wave length of the reflecting member shown in Fig. 5; Fig. 8 is a graph of a relationship of reflectivity vs. wave length of another reflecting member; Fig. 9 is a graph of a relationship of average color rendering index vs. wave length of another reflecting member;; Fig. 10 is a graph of a relationship of spectroscopic reflectivity vs. wave length of a reflecting member with a multi-layer shown in Table 2; Fig. 11 is a graph showing a relationship of spectroscopic reflectivity vs. wave length of a reflecting member with a multi-layer shown in Table 3; and Figs. 12A through 12E show the illustration of a modification of a halogen lamp as a light source, in which Figs. 12A and 12B are a front view and a side view of the halogen lamp, Fig. 12C shows the angle at which a luminous flux is supplied from a filament to the reflecting member, Fig. 12D shows an illumination pattern of reflecting rays of light, and Fig. 12E shows a composite illumination pattern of reflecting rays of light.

A lighting fixture according to an embodiment of the present invention will be described with reference to the accompanying drawings.

In Fig. 4, a tubular main frame 1 of a lighting fixture is supported by a support pole 2 whose base end is fixed to a structure, e.g., ceiling. More specifically, the main frame 1, supported by the support pole 2, is movable vertically and horizontally at the top end of the support pole 2. A lamp socket 3 is located at the central portion of the main frame 1 as viewed from the front side of the main frame. A tubular shade 4 defines the front part of the main frame 1. A reflecting member 5 is located inside and supported by the shade 4. The reflecting member 5 receives at the central hole a halogen lamp 6 whose metal end is inserted into the lamp socket 3. The reflecting member 5 with a front opening 7 is shaped like a fan receives rays of light from the halogen lamp 6 located at the central portion and reflects and projects them through the front opening 7 to exterior. In this instance, the halogen lamp 6 may be any of halogen lamps of low voltage, i.e., lower than 100 V, preferably 28 V or less, for example, 6 V, 12 V, 24 V, and 28 V. A rim-like holder 8, which is mounted to the inner wall of the front part of the shade 4 or a part of the shade 4 closer to its front opening, holds the reflecting member 5.

The reflecting member 5 includes a substrate 10, a light absorbing layer 11 and a multiple layer 12. The substrate 10 is made of opaque material, such as a metal plate (e.g., an aluminum plate), a synthetic resin plate, and a ceramic plate as that it constitutes a reflector having a relatively high reflection factor.

The light absorbing layer 11 is formed over the substrate 10 and made of titanium carbide, silicon carbide, or chromium compound. The multiple layer 12 is layered over the light absorbing layer 11 and is an optical multi-layer film to cut off the heat wave contained in the radiation from the halogen lamp, and to reflect the rays of visible rays of light. Further, the multi-layer film 12 receives the rays of light emitted from the halogen lamp, increases its color temperature, and reflects the light of color which is different from that of the incident light. In the optical multi-layer film 12, titanium oxide (TiO2) layers 13 of high refractivity and silicon oxide (SiO2) layers 14 of low refractivity are alternately layered in successive order.When the thickness and the number of the layers 13 and 14 are appropriately selected, the multi-layer film 12 cuts off the infrared rays contained in the rays of light emitted from the lamp 6, reflects the visible rays of light, and increases a color temperature of the incident light to change the incident light into a white light, which is in turn reflected or projected.

As mentioned above, the substrate 10 of the reflecting member 5 is made of opaque material. If required, transparent material may be used for the substrate 10. An example to realize this is shown in Fig. 6. As shown, the reflecting member 5 contains a substrate 10 made of transparent material, such as glass and synthetic resin, and an optical multi-layer film 12, which consists of a multiple of paired layers, a titanium oxide (TiO2) layer 13 of high refractivity and a silicon oxide (SiO2) layer 14 of low refractivity.

With such a structure of the reflecting member 5, after passing the multi-layer film 12, the infrared rays transmit through the substrate 10.

The operation of the lighting fixture thus arranged will be described.

The halogen lamp 6, which is a light source of a lighting fixture, e.g., a spot light, and is fixed to a structure, e.g., ceiling, is lit on. The rays of light emitted from the halogen lamp 6 are incident on the reflecting member 5. In the reflecting member, the heat waves or infrared rays contained in the incident rays of light are cut off. A color temperature of the visible rays of light is increased to be higher than that of the light of the halogen lamp. Accordingly, the reflected light has such a high color temperature, that is, it is a white light. Thus, the white light is projected through the front opening 7 of the reflecting member 5 of the lighting fixture. The light reflected by the multi-layer film 12, even if its color temperature is increased up to 4000 K, suffers from little degradation of its illumination and has a high average color rendering index.

The optical multi-layer film 12 is formed as shown in Table 1.

Table 1

Film Material Film Thickness (nd/A 1st layer Titanium oxide (TiO2) 0.33 2nd layer i Silicon oxide (SiO2) 0.33 3rd layer Titanium oxide (TiO2) 0.25 4th layer Silicon oxide (SiO2) 0.25 5th layer Titanium oxide (TiO2) 0.25 6th layer Silicon oxide (SiO2) 0.25 7th layer Titanium oxide (TiO2) 0.25 8th layer Silicon oxide (SiO2) 0.25 9th layer Titanium oxide (TiO2) 0.125 In the above table, "n" indicates refractivity, "d" actual thickness, and the controlled wave length "A" is 430 nm. A relationship of reflectivity vs. wave length of the multi-layer film 12 (vertical incident rays) thus formed is as shown in Fig. 7.

In the lighting fixture constructed by using a halogen lamp of the single end metal type operating at 12 V and 100 W, and the reflecting member 5 consisting of the optical multi-layer 12, the light absorbing layer 11, and the aluminum substrate 10 which are layered in this order from top to bottom, at 4000 K of color temperature of the projected light, its illumination degradation is 34% of that of an aluminum reflecting plate whose reflectivity is 85%, and is 36% of that of a conventional dichroic film (which reflects the visible rays of light but transmits infrared rays). Further, an average color rendering index (Ra) of the light projected from the lighting fixture is high, 90. In the color rendering properties, the present lighting fixture is superior to a discharge lamp of high brightness.

A reflecting member whose reflectivity varies against a wave length as shown in Fig. 8 may be used for the lighting fixture.

As described above, the lighting fixture as mentioned above comprises a halogen lamp of the one-end metal type operating at voltage lower than 100 V, and a reflecting member disposed in opposition to said halogen lamp to reflect and project the rays of light emitted from said halogen lamp, wherein an optical multi-layer film is formed over the surface of said reflecting member, said optical multi-layer film functioning to cut off heat waves coming from said halogen lamp, to reflect the visible rays of light, and reflects the rays of light whose color temperature is higher than that of the incident light from said halogen lamp. With such an arrangement, it is easy to form a white light whose color temperature is at least 4000 K.Since the halogen lamp is of the low voltage type, viz., operable at a voltage lower than 100 V, an object can vividly be illuminated with the combination of the sharp beams of light and the beams of white light. Further, since a filter is not used, the color of the light emitted from the light source will never be changed, providing a natural feeling of color. The average color rendering index of the projected light of the lighting fixture is at least 85. In this respect, the lighting fixture is more excellent in the color rendering properties than the discharge lamp of high brightness. Accordingly, the light fixture according to the present invention is small in size and low in cost.

A peak reflectivity of the reflecting member 5 is preferably in the range from 430 nm to 500 nm. Use of such a reflecting member provides less illumination degradation and little damages the color rendering properties.

A graph of Fig. 9 showing relationships of efficiency of utilization/average color rendering index vs. wave length, describes the preferable range of the peak reflectivity. Where a halogen lamp whose color temperature is 2850 K is used as a light source 6, if the components of short wave lengths are first removed from a light, its illumination starts to fall off at 500 nm, as indicated by a curve A in Fig. 9. And its average color rendering index starts to drop at 430 nm or so, as indicated by a curve B.

The optical multi-layer film 12 to realize the reflecting member 5 having such a reflectivity may be formed as shown in Table 2.

Table 2

Film Material Film Thickness (nd/A) 1st layer Titanium oxide (TiO2) 0.34 2nd layer Silicon oxide (SiO2) 0.34 3rd layer Titanium oxide (TiO2) 0.34 4th layer Silicon oxide (SiO2) 0.25 5th layer Titanium oxide (TiO2) 0.25 6th layer Silicon oxide (SiO2) 0.25 7th layer Titanium oxide (TiO2) 0.25 8th layer Silicon oxide (SiO2) 0.25 9th layer Titanium oxide (TiO2) 0.13 In Table 2, the respective factors are equal to those in Table 1.A spectroscopic reflectivity of the multi-layer film shown in Table 2 varies as shown in Fig. 10. As shown, its peak is at 470 nm. In this case, the light is incident at an angle of 90".

It is preferable to set the peak reflectivity of the reflecting member 5 within the range of 530 nm to 550 nm at room temperature. When the halogen lamp is lit on and the reflecting member is heated to a high temperature, the light reflected by the optical multilayer film 12 of the reflecting member shifts to the short wave length side. If the reflecting member whose peak reflectivity is selected within the above range is used, the light projected from the lighting fixture is confined within a wavelength region of green. Accordingly, the lighting fixture projects a green light without any color displacement. Such a colored light is suitable for the illumination of a garden plant, for example.

The optical multi-layer film 12 to realize the reflecting member whose peak reflectivity is selected within the above range may be formed as shown in Table 3.

Table 3

Film Material Film Thickness (nd/A) 1st layer Titanium oxide (TiO2) 0.75 2nd layer Silicon oxide (SiO2) 0.25 3rd layer Titanium oxide (TiO2) 0.75 4th layer Silicon oxide (SiO2) 0.25 5th layer Titanium oxide (TiO2) 0.75 6th layer Silicon oxide (SiO2) 0.25 7th layer Titanium oxide (TiO2) 0.75 8th layer Silicon oxide (SiO2) 0.25 9th layer Titanium oxide (TiO2) 0.75 In Table 3, the respective factors are equal to those in Table 2.A spectroscopic reflectivity of the multi-layer film shown in Table 3 varies as shown in Fig. 11.

By appropriately selecting the thickness and the number of the layers 13 and 14, the multi-layer film can reflect the light emitted from the halogen lamp in the form of light beams of a desired color, for example, red and blue. The light components, e.g., visible rays and infrared rays, that passed through the optical multilayer film, not reflected by it, are absorbed by the absorbing layer 11. In this case, the substrate 10 is preferably made of opaque material. If so, the light components passed through the reflecting member 5 can be cut off more reliably. The resultant reflecting member is light in weight, and large in size, and is reliable and easy to handle.

The halogen lamp is preferably the lamp denoted as C6 or CC6 described in JIS (Japanese Industrial Standard) as shown in Figs. 12A and 12B. As shown, the lamp is a halogen lamp of the one end metal type in which, as shown, a filament 16 shaped like a bar as viewed from the front side is disposed at the central portion within a transparent enclosure 15.

In the lighting fixture using such a halogen lamp, as shown in Fig. 12A, the light beams that are emitted from both ends of the filament 16 of the halogen lamp 6 and are incident on reflecting points al, a2, bl, b2, cl and c2 on the reflecting member 5, contain a less amount of component of light whose incident angle is smaller than that of the light beam emanating from the center of the filament 16. When viewed in cross section, as shown in Fig. 12B, the light beams that emanate from the center of the filament 16 of the lamp 6 and enter the respective reflecting points al, a2, bl, b2, cl and c2 on the reflecting member 5, resemble points, and no problem arises. An apparent angle e of the light beams emanating from both ends of the filament 16 is smaller than that of the case shown in Fig. 12c. Accordingly, the difference of the spectroscopic reflectivity between them is small. An illumination pattern of the reflecting light at point "a" contains a white W at the mid point, and bluish color B at both ends, as shown in Fig. 12D. An illumination composite pattern of the reflecting lights at the points al, a2, bl, b2, cl and c2, as shown in Fig. 12E, contains less color irregularity. Accordingly, the white light as projected is bluish, providing fresh feeling, and contains little yellow which would give rise to uncomfortable feeling.

Claims (10)

Claims:

1. A lighting fixture comprising: a halogen lamp of the single end metal type operable at a voltage lower than 100 v to emit rays of light; and a reflecting member disposed in opposition to the halogen lamp and reflecting the rays of light emanating from the halogen lamp, said reflecting member containing an optical multi-layer film which reflects the visible rays of light contained in the light emanating from said halogen lamp to increase the color temperature of the reflecting light to be higher than that of the light emanating from said halogen lamp.

2. A lighting fixture comprising: a light source for emitting a light including a component of a predetermined color; and a reflecting member disposed in opposition to the light source, including a reflector having a relatively high reflection factor, an optical multi-layer film for reflecting the light component of a predetermined color in the light emitted from the light source, and light absorbing film provided between the reflector and the optical multi-layer film.

3. The lighting fixture according to claim 1, in which said optical multi-layer film contains a multilayer film to increase the color temperature of the light emanating from said halogen lamp up to 4000 K and reflects the light at 4000 K of color temperature.

4. The lighting fixture according to claim 1, in which said reflecting member contains a light absorbing layer interposed between said optical multi-layer film and said substrate.

5. The lighting fixture according to claim 4, in which said light absorbing layer absorbs the lights and the infrared rays of light that pass through said optical multi-layer film.

6. The lighting fixture according to claim 1, in which said reflecting member has a spectroscopic reflectivity characteristic in which a peak reflectivity is within the wavelength range of 530 nm to 550 nm at room temperature.

7. The lighting fixture according to claim 1, in which said reflecting member has a spectroscopic reflectivity characteristic in which a peak reflectivity is within the wavelength range of 430 nm to 500 nm at room temperature.

8. The lighting fixture according to claim 1, in which said reflecting member includes a fan-like reflecting member with a front opening and a halogen lamp disposed therein, said halogen lamp containing a linear filament extending toward said front opening.

9. The lighting fixture according to claim 1, in which said halogen lamp is of the low voltage type operable at a voltage of 12 V.

10. A lighting fixture, substantially as hereinbefore described with reference to Figs. 4 to 12E of the accompanying drawings.