JPS62273594A - Illuminator for transmitting image display unit - 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 3. Detailed Description of the Invention Field of Industrial Application The present invention relates to an illumination device that is disposed on the back side of a transmissive image display device and illuminates the image display element uniformly from the back side.

Conventional Technology Transmissive image display devices using image display elements such as liquid crystals use an illumination device as shown in FIG. 7, for example, in order to brightly and uniformly illuminate the image display elements from the back side. .

That is, a reflecting plate 2 with a parabolic cross section is provided below the linear light '#, 1 in order to efficiently condense the light irradiated from the light 'a1', and the reflecting plate 2 is provided with a parabolic cross-sectional shape to efficiently collect the light emitted from the light source 1 and the reflected light. By irradiating the diffuser plate 3 provided above the light source 1 with the reflected light from the plate 2, the back surface of the image display element 4 placed parallel to the diffuser plate 3 is illuminated.

Problems to be Solved by the Invention In such a conventional lighting device, since the cross-sectional shape of the reflection plate 2 is a parabola, a part of the light from the light source 1 reflected by the reflection plate 2 is reflected by the diffusion plate 3. It is irradiated almost perpendicularly to the object. Only the reflected light from this reflector 2 is transmitted to the diffuser plate 3.
If the light is irradiated on the diffuser plate 3, the 1 degree distribution of the diffuser plate 3 will be nearly uniform. However, since the diffuser plate 3 is irradiated with direct light from the light source 1 in addition to the reflected light, the 91 degree distribution is a combination of the direct light and the reflected light, as shown in FIG. Since the brightness in the vicinity is high and the brightness decreases toward the end of the diffuser plate 3, the brightness of the image display element 4 becomes non-uniform.

As a method of making the i1 degree distribution of the diffuser plate 3 uniform, it is possible to block direct light from the light source 1, or to make the i1 degree distribution of the diffuser plate 3 uniform. : It is possible to change the material to a material with high diffusion characteristics (one that approximates a perfect diffusion surface as much as possible, such as opal glass), but either method is undesirable because it reduces the light utilization efficiency of the light source 1.

Therefore, the present invention makes the luminance distribution of the diffuser plate uniform without reducing the efficiency of using light from the light source.

Means for solving the problems and technical means of the present invention for solving the above problems are as follows:
In addition to the direct light from the light source and the reflected light from the reflective member, it is attempted to make the brightness distribution of the diffuser plate uniform by combining the transmitted light that passes through the interior of the reflective member.

action The effect of this technical means is as follows.

That is, a reflective member having the functions of both a reflective mirror and a light guide is provided below the light source, direct light from the light source is irradiated near the center of the diffuser plate, and the reflected light from the surface of the reflective member is directed to the diffuser plate. Irradiates the entire area. The process up to this point is the same as the conventional technology. Furthermore, by irradiating the transmitted light from the inside of the reflective member (light guide) to the parts where the brightness of the diffuser plate normally decreases, that is, to both ends of the diffuser plate, the direct light from the light source and the reflection from the reflective member can be irradiated. Since light and transmitted light can be irradiated onto the diffuser plate in a well-balanced manner, a uniform brightness distribution can be achieved.

EXAMPLE Hereinafter, a first example of the present invention will be described based on the accompanying drawings.

In FIG. 1, reference numeral 5 denotes a linear light source (for example, a fluorescent lamp), and a diffusion plate 6 is provided above the light source 5 in parallel with the tube axis direction of the light source 5.

Furthermore, there is an image display element 7 placed above the diffuser plate 6 in parallel with the diffuser plate 6, and the diffuser plate 6 and the image display element 7 are arranged as follows.
They are arranged close to each other with an interval of several mm. On the other hand, a reflecting member 8 whose cross-sectional shape is partially a parabola is provided below the light source 5, and the light source 5 is placed at the focal point of this parabola.

The material of the reflective member is transparent acrylic resin, and its structure is as shown in FIG. A metal vapor-deposited film of aluminum is applied to the part other than the part (which is transparent with a width of A along the tube axis direction of the light source 5), that is, the part whose cross-sectional shape is a parabola. It serves as a reflecting mirror for totally reflecting a part of the light from the diffuser plate 5 in the direction of the diffuser plate 6. The inside of the reflection member 8 is a light guide in which the light incident thereon is repeatedly reflected by the wall surface and transmitted through the reflection member 8, and a part of the light from the light source 5 is made to enter from A to both ends of the diffusion plate 6. It has a structure that allows it to be irradiated.

By configuring the lighting device as described above, the diffusion plate 6
Among the light irradiated from the light [5], the light irradiated directly (direct light), the light reflected by the reflective mirror of the aluminum metal vapor deposited film on the surface of the reflective member 8 (reflected light), and the reflective member The light that is synthesized with the light that is repeatedly reflected and transmitted inside 8 (transmitted light) will be irradiated.
The luminance distribution on the diffuser plate 6 is as shown in FIG.

In FIG. 3, (a) is 1 due to direct light from the light source 5.
(b) is the brightness distribution due to the reflected light from the reflective member 8, (c) is the brightness distribution due to the transmitted light from the reflective member 8, and when (a), (b), and (c) are combined, the target is achieved. A brightness distribution (d) is obtained.

Next, a second embodiment of the present invention will be described.

FIG. 4 shows a second embodiment, in which the reflecting member 9 is composed of a reflecting plate 10 and a reflecting plate 11.

In this embodiment, reflective plates 10 and 11 are made of aluminum plates with high specularity, and their cross-sectional shapes are parabolic. A linear light source 5 (for example, a fluorescent lamp) is arranged at a pointless position of this parabola, as in the first embodiment. A diffuser plate 6 is provided above the light source 5 in parallel to the tube axis direction of the light J5, and a diffuser plate 6 is provided above the diffuser plate 6.
There is an image display element 7 placed parallel to. The diffusion plate 6 and the image display element 7 are arranged close to each other with an interval of several mm, and the specifications and positional relationships of the components of the light source 5, the diffusion plate 6, and the image display element 7 are based on the first one. It is the same as the example.

On the other hand, the reflection member 9 is provided below the light source 5, and the reflection plate 10 and the reflection plate 11 are arranged at an appropriate interval so that the space between the reflection plate 10 and the reflection plate 11 is hollow.
This gives it the effect of a light guide. Also, light source 5. As shown in FIG. 5, a rectangular opening is provided directly below the light source 5 (portion B in FIG. 4) in the reflecting plate 10 facing the light source 5 along the tube axis direction of the light source 5. Light source 5
A part of the light enters through this opening and is reflected between the reflector plate 10 and the reflector plate 11, and is irradiated onto both ends of the diffuser plate 6.

By configuring the lighting device as described above, the diffusion plate 6
Of the light emitted from the light source 5, the light emitted directly (direct light), the light reflected by the reflecting plate 10 of the reflecting member 9 (reflected light), and the light emitted from the reflecting plate 10 and the reflecting plate 11. The light that is synthesized with the light that is repeatedly reflected between the two (transmitted light) will be irradiated, and the luminance distribution on the diffuser plate 6 will be as shown in FIG. In FIG. 6, (e) shows the brightness distribution due to direct light from the light source 5, and (f) shows the reflective member 9.
Of these, (g) is the luminance distribution due to the light transmitted between the reflecting plate 10 and the reflecting plate 11 of the reflecting member 9, and (e) is the luminance distribution due to the light reflected from the reflecting plate 10. By combining (g), the target luminance distribution (h) is obtained.

Note that although highly specular aluminum plates were used for the reflective plate 1o and the reflective plate 11 constituting the reflective member 9t, it is also possible to use a reflective plate made of acrylic resin or the like with aluminum vapor-deposited instead of the aluminum plate. It has a similar effect.

In addition, in the first and second embodiments, a straight tube fluorescent lamp was used as the light source 5, but linear light sources such as a cold cathode discharge lamp, a segmented halogen bulb, and even a tungsten lamp may also be used. A plurality of LHDs connected in a linear manner may also be used.

Effects of the Invention The present invention has a configuration in which a reflective member whose surface facing the light source is a reflective mirror and whose interior is a light guide is provided below the light source. By irradiating both ends of the diffuser plate with the transmitted light, it is possible to prevent a decrease in brightness at both ends of the diffuser plate, which has been a problem with conventional lighting devices, and achieve a uniform brightness distribution.

In addition, among the light emitted from the light source, the direct light, the reflected light from the reflective mirror on the surface of the reflective member, and the transmitted light from inside the reflective member can all be irradiated onto the diffuser plate.
The light source's light usage efficiency is excellent.

[Brief explanation of the drawing]

The first country is a sectional view showing the configuration of the lighting device in the first embodiment of the present invention, FIG. 2 is a perspective view of the reflective member in the lighting device of the first embodiment, and FIG. 3 is the first embodiment. FIG. 4 is a sectional view showing the configuration of the lighting device in the second embodiment of the present invention; FIG.
The figure is a perspective view of the reflecting member in the lighting device of the second embodiment, FIG. 6 is a brightness distribution characteristic diagram of the diffuser plate in the lighting device of the second embodiment, and FIG. 7 is the configuration of a conventional lighting device. The cross-sectional view, FIG. 8, is an 11 degree distribution characteristic diagram of a diffuser plate in a conventional lighting device. 5...Light source, 6...Diffusion plate, 7...Image display element, 8 and 9...Reflective member, 10 and 11...Reflector Name of agent Patent attorney Toshio Nakao Haka 1 1st Image in Figure 7 Display nest L Aluminum spotting surface Figure 3 Disapproval version (fJ Immunity 4 Figure 7 Image projection Ho Kiko Figure 5 Revisited parts Figure 6 S

Claims (1)

[Claims] A linear light source, a reflecting member provided below the light source to reflect and transmit a part of the light from the light source, and a reflecting member provided above the light source to reflect direct light from the light source and reflection from the reflecting member. Equipped with a diffuser plate that is irradiated with light and transmitted light,
An illumination device for a transmissive image display device, wherein the surface of the reflective member is a reflective mirror, and the interior of the reflective member is a light guide.