JPH0476503A - Lighting apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] This invention relates to improving the efficiency of a lighting device equipped with a light guide.

[Prior Art] FIG. 4 is a sectional view showing a conventional illumination device of this type disclosed in, for example, Japanese Unexamined Patent Publication No. 1-154086.

In the figure, (1) is a light source, (2) is a transparent plate made of acrylic resin or the like, (3) is a light incident surface of this transparent plate (2), and (4) is the transparent plate ( 2) is the light exit surface.

(5) is a light guide constructed by laminating a plurality of transparent plate-like bodies (2), and (6a) is a light reflector disposed facing the light exit surface of the light guide (5). , (6b) is a light reflector placed around the light source (1).

The light reflectors (6a) and (6b) are integrated.

It is provided so as to cover the light exit surface of the light guide (5) and the light source (1).

In the illumination device having such a configuration, among the light emitted from the light source (1), the light incident on the light entrance surface (3) is
The incident light travels through the transparent plate-like body (2) while repeating total reflection, exits from each light exit surface (4), is reflected by the light reflector (6a), and passes through the light guide (5). Go across and exit the lighting device.

On the other hand, among the light emitted from the light source (1), the light reflector (6
Part of the light incident on b) is reflected by the light reflector (6b) and then enters the light incident surface (3) of the transparent plate (2), and some of the light is reflected by the light reflector (6b) and then enters the light incidence surface (3) of the transparent plate (2). While repeating reflection with the reflector (6b), the light travels in the direction of the light entrance surface (3) of the transparent plate-like member (2) and enters the light entrance surface (3). enters the light source (1) again.

Some of the light that re-enters this light source (1)
) enters the light incident surface (3), travels through the transparent plate (2), and is reflected by the light reflector (6a).

Although the light is emitted to the outside of the light guide (5), most of the light is lost.

[Problems to be Solved by the Invention] As described above, in the conventional lighting device, since the light reflector (6a) is arranged in contact with the light emitting surface, part of the light emitted from the light source (1) Only the light incident on the light incidence surface (3) will be emitted outside from the light guide (5) through the above-mentioned path, but the light guide (5) is made of a refracting material such as acrylic resin. Since it is composed of materials with a ratio of 1 or more,
Not all the light that reaches the light incidence surface (3) enters the light guide (5), but depending on the angle of incidence or the light incidence surface (3).
Due to the surface condition of the light incident surface (3), there is a lot of light that does not enter the light guide (5), so the light that does not enter becomes heat and is lost, and is also returned to the light source (1). The proportion of the incident light that goes out of the light source (1) again is very small, and most of it becomes a loss, and a considerable proportion of the light emitted from the light source is guided from the light incidence surface. Since the light cannot enter the light body, resulting in loss, there is a problem in that the proportion (efficiency) of light emitted outside the lighting device is low.

This invention was made in order to solve the above-mentioned problems, and an object thereof is to obtain a highly efficient lighting device.

[Means for Solving the Problems] A lighting device according to the present invention is one in which a gap is provided between a light reflector, a light output surface portion of a light guide, and a light source.

[Function] In the present invention, a gap is provided between the light reflector, the light exit surface of the light guide, and the light source.

Light that cannot enter the light guide plate passes through the light guide plate, and this light goes directly to the light reflection plate without passing through the light guide plate, is reflected by the second reflection plate, and is emitted to the outside of the lighting device.

U example An embodiment of the present invention will be described below.

In FIG. 1, (1) to (5) are the same as the conventional lighting device described above.

(6a) is a light reflector placed opposite the output surface of the light guide (5), (6b) is a light reflector placed around the light source (1), and (7) is a transparent plate-like body. (2) Light exit surface (4
) is the envelope surface of the exit surface of the light guide (5) obtained by sequentially connecting the top sides of the light guide (5).
6a).

The light reflectors (6a) and (6b) are constructed as an integral and continuous body as in the case of the conventional lighting device described above.

The air gap (8a) extends in the direction of the light source (1) and is not only between the envelope surface (7) and the light reflector (6a) but also between the light source (1)
A gap (8b) is also provided between the light reflector (6b) and the light reflector (6b).

In the illumination device configured in this way, among the light emitted from the light source (1), the light incident on the light incidence surface (3) is transmitted to the incident transparent plate-like Proceeds through the body (2) while repeating total reflection, exits from the light output surface (4), is reflected by the light reflector (6a),
Exit the lighting device by crossing the light guide (5).

On the other hand, among the light emitted from the light source (1), the light reflector (6b
) passes through two different paths.

The first case is when the light emitted from the light source (1) is incident on the R1 portion of the light reflector (6b) shown in FIG.

As in the case of conventional lighting devices, a portion of the light reflected by the light reflector (6b) is reflected repeatedly between the light source (1) and the light reflector (6b) and reaches the light incidence surface (3). The light travels in the direction and enters the light entrance surface (3), and most of the light enters the light source (1) again.

Of the light re-entering this light source (1), a part
) enters the light incident surface (3), travels through the incident transparent plate-like body (2) while repeating total reflection, exits from the light exit surface (4), and is reflected by the light reflector (6a). It is reflected and emitted to the outside of the light guide (5) and exits the lighting device.

The second case is when the light reflected by the light reflector (6b) enters the R2 portion of the light reflector (6b) shown in FIG. 8b) in the direction of the air gap (8a).

Also, a part of the light is reflected between the light source (1) and the light reflector (6b).
It repeats the irradiation, re-enters the light source (1), or enters the air gap (8a).
).

The light that has advanced into the gap (8a) is reflected by the light reflector (6a), crosses the light guide (5), and exits the lighting device.

Furthermore, some of the light emitted from the light source (1) directly enters the light reflector (6a), and in this case, it is also reflected by the light reflector (6a) and passes through the light guide (5). Get out of the lighting equipment.

As is clear from the above, in this invention, in addition to the light that enters each incident surface of the light guide (5), undergoes repeated total reflection, and then enters the light reflector (6a), Light body (5
), more light enters the light reflector (6a) without passing through the light reflector (6a), and more light is emitted outside the lighting device, dramatically increasing efficiency.

Figure 2 (b) compares the illuminance on the illuminated surface 30 cm away from the illumination device with and without gaps (8a) and (8b) as shown in Figure 2 (a). 3 is an illuminance distribution diagram shown in which the point at distance=0 is the point directly below the light source.

As can be seen from this figure, the voids (8a) and (8)
It can be seen that when installing b), the illuminance increases significantly.

Moreover, as shown in FIG. 3, by making the shape of the light reflector (6a) concave with respect to the envelope surface (7).

In the case of a path that is reflected by this light reflector, crosses the light guide (5), and exits the lighting device, the incident angle to the light guide (5) becomes small, so the loss at the time of incidence is reduced. Further increases in efficiency can be expected.

Further, in the above embodiment, the light reflector is integrated from the exit surface of the light guide (5) to the periphery of the light source (1), but it may be configured as a separate type.

[Effects of the Invention] As described above, a gap is provided between the light reflector and the light output surface of the light guide and the light source, so that light that cannot enter the light guide plate passes through the gap. The light passes directly to the light reflection plate, is reflected by the light reflection plate 9, and is emitted to the outside of the lighting device, which has the effect of increasing efficiency.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a lighting device showing an embodiment of the present invention;
FIG. 2 is an explanatory diagram when measuring the effect of voids and an illuminance distribution diagram showing the measurement results, and FIG. 3 is a sectional view of a lighting device showing another embodiment of the present invention. FIG. 4 is a sectional view showing a conventional lighting device. In the figure, (1) is a light source, and (2) is a transparent plate. (3) is a light entrance surface, (4) is a light exit surface, (5) is a light guide (6a), (6b) is a light reflector, (7) is an envelope surface,
(8a) and (8b) are voids. Note that the same reference numerals in each figure indicate the same or corresponding parts. No. iml Fig. 3

Claims (1)

[Claims] A light guide consisting of a plurality of laminated transparent plate-like bodies and having a light incident surface and a light exit surface formed by one end surface and the other end surface of the plurality of transparent plate-like bodies, respectively; and this light guide. a light source placed opposite the light incidence surface of the light body;
a light reflector disposed opposite to the light output surface of the light guide, and a gap is provided between the light reflector and the envelope surface of the light output surface of the light guide and the light source. A lighting device characterized by: