JPS6248324B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to lighting equipment such as road lights and floodlights, in which a lamp 2 is disposed within a box-shaped reflector 1 with an opening at the front, and a transparent plate 3 is attached to the front opening of the reflector 1. The present invention also relates to a lighting device characterized in that an antireflection film 4 is provided on a light-transmitting plate 3.

When lighting expressways, elevated roads, bridges, etc., it is necessary to regulate the lighting angle in order to increase the illumination rate of the road surface and to prevent light from shining onto surfaces other than the road surface from becoming glare and causing light pollution. Therefore, when the road surface 5 is illuminated at an angle of θ by the lighting fixture A as shown in FIG. 1a, the lamp 2 as shown in FIG. 1b
The angle θ' at which the opening of the reflector plate 1 is viewed is the angle θ' of the lighting fixture A.
is set to be approximately equal to the angle θ when looking into the road, and the inner surface shape of the reflector plate 1 is designed so that the reflected light falls within the range of θ' and the brightness distribution is improved. The cross-sectional light distribution of lighting fixture A at this time is as shown by the solid line in the graph of FIG.

However, when a transparent plate 3 such as a glass plate is attached to the front opening of the reflective plate 1, a part of the direct light from the lamp 2 that enters the transparent plate 3, and some of the light that is reflected off the reflective plate 1 is absorbed by the transparent plate 3. A part of the reflected light incident on the transparent plate 3
The reflected light hits another part of the reflecting plate 1, and this reflected light enters the transparent plate 3 again, where part of the light is reflected and the rest is transmitted and comes out. Since the traveling direction of the light emitted here is no longer controlled, it deviates from the angle θ' as shown in Figure 3, resulting in a light distribution as shown by the dotted line in the graph of Figure 2. The intended purpose of regulating the illumination angle cannot be achieved. Therefore, the fourth
It is conceivable to incline the light-transmitting plate 3 as shown in Figure a so that the light reflected by the light-transmitting plate 3 does not adversely affect the regulation of the illumination angle. Since it is difficult to adjust the angle, it is difficult to expect an effect, and since the reflection of light on the transparent plate 3 cannot be prevented, the light transmittance cannot be improved and the illumination efficiency decreases. It is also possible to attach a louver 5 to the inner surface of the transparent plate 3 to prevent the light reflected by the transparent plate 3 from re-entering the reflecting plate 1, but in this case, the louver 5 is considered an obstacle. As a result, the lighting efficiency was significantly reduced.

The present invention has been made in view of the above points, and has an object to prevent the regulation of the illumination angle from being disturbed by the light-transmitting plate, prevent the occurrence of glare due to light leakage, and increase illumination efficiency. The purpose of the present invention is to provide a lighting device that can perform the following functions.

The present invention will be explained in detail below with reference to Examples. Reflector 1
A similar design can be used as shown in FIG. It is installed. An anti-reflection film 4 made of a thin film of magnesium fluoride or the like is formed on the inner and outer surfaces of the reflector 1.
is formed by coating as a single layer or multiple layers as shown in FIG. As this thin film, a metal thin film can also be used as long as it has an antireflection effect.

When illumination is performed using the light-transmitting plate 3 coated with this anti-reflection film 4, the reflectance in the visible light region of the light-transmitting plate 3 is higher than that of a general glass plate, as shown in the graph of FIG. Since it is about 10 to 30% of that, the reflection by the transparent plate 3 is suppressed as shown in Figure 6, and the generation of light rays that travel beyond the angle θ' due to the influence of the reflected light by the transparent plate 3 is prevented. This can be prevented, and the light distribution becomes close to that of the solid line without using the transparent plate 3, as shown by the dashed line in FIG. Furthermore, the fact that there are fewer reflected components means that the light transmittance increases, as shown in the graph of FIG. 7, and as a result, the illumination efficiency also improves. In particular, glass coated with a thin film of magnesium fluoride has good light transmittance and is therefore suitable for use as the antireflection film 4, and the principles of the present invention can be applied to other general lighting equipment.

As described above, in the present invention, a light transmission plate is attached to the front opening of the reflection plate, and an anti-reflection film is provided on the light transmission plate, so that direct light from the lamp that enters the light transmission plate or light reflected from the reflection plate can be reflected. It can prevent light from being reflected by a light-transmitting plate, and it can also prevent light from leaking outside the required range of illumination angles and causing glare due to the influence of light reflected from the light-transmitting plate. Since reflection can be prevented, the transmittance of light to the light-transmitting plate can be improved and illumination efficiency can be improved.

[Brief explanation of the drawing]

Figures 1a and b are an overall front view and cross-sectional view showing the angle of irradiation, Figure 2 is a graph showing the light distribution of the lighting equipment, Figure 3 is a cross-sectional view of the conventional example, and Figures 4a and b are A cross-sectional view of another conventional example, FIG. 5 is a cross-sectional view of a transparent plate used in the present invention, and FIG. 6 is a cross-sectional view of the same lighting equipment as above.
FIG. 7 is a graph showing a comparison of light reflection. 1 is a reflective plate, 2 is a wrap, 3 is a transparent plate, and 4 is an antireflection film.

Claims (1)

[Claims] 1. A lighting device comprising: a lamp disposed within a box-shaped reflector with a front opening; a light-transmitting plate is attached to the front opening of the reflector; and an anti-reflection film is provided on the light-transmitting plate.