JPS61179005A - Surface 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] [Field of Industrial Application] The present invention relates to a surface illumination device for illuminating household electrical appliances, display devices of various industrial equipment, instrument panels of automobiles, etc. from the back side. In particular, it is possible to efficiently display images using a large-sized liquid crystal display element and to obtain uniform and arbitrary brightness for each arbitrary display area.

[・Conventional technology]

Fig. 4 (a), Fig. 4 (b) t'i, for example, Utsuka Sho 5
2-116183, FIG. 4(a) is a plan view showing the display state, and FIG. 4(b) is a sectional view. In both figures (a) and 4), reference numeral 1 indicates a transparent substrate, and reference numeral 2 indicates a light source disposed on the end face of the central portion of the transparent substrate.

A display board 3 is arranged on the front side of the transparent substrate l.

Transparent display portions 3a to 3d are formed on the display panel 3, and has a pattern layer 3x forming the display portions 3a to 3d.

Further, reference numeral 4 denotes a reflecting plate for reducing light leakage loss from the back and side surfaces, or for holding each of the above-mentioned elements in a predetermined position.

The transparent substrate 1 has light diffusive treatments 1a to 1d on the back surface,
In the display portion far from the light source 2, light-diffusing dust is enlarged.

Next, the operation will be explained. Light emitted from the light source 2 enters the transparent substrate 1 and propagates inside. On the way, when the light reaches the light diffusive treatments 1a to 1d, a portion of the light is diffused and emitted forward.

Part of the light is reflected by the display panel 3, and the light emitted backward is reflected by the reflector 4, so that the light intensity within the transparent substrate 1 eventually becomes K as shown in FIG. 5(d).

The distribution of this light intensity can be measured by temporarily applying light diffusive treatment to a small area that does not disturb the distribution and measuring the brightness of that area one after another.

The temporary light-diffusing treatment is realized, for example, by attaching small pieces of light-transmitting adhesive tape 9 . Fifth
The degree of light expansion of the light diffusive treatments 1a to 1d of the transparent substrate 1 as shown in the K cross section in Figure (a) and the plan view in Figure 5 (b) means that light proportional to the size of the transparent substrate 1 is diffused and emitted. The intensity of the light emitted from the transparent substrate 1 through the display panel 3 to the front (front), that is, the brightness, is proportional to the degree of light expansion and is also proportional to the light intensity within the transparent substrate 1, so the distribution is proportional to the product of the degree of light expansion and the light intensity within the transparent substrate.

The brightness of the display portion of the display board 3 becomes blurred at the pattern portion forming the display portion of the display board 3, as shown in FIG. 5(e).

[Problem that the invention seeks to solve]

Since the conventional surface illumination device is configured as described above, the brightness of the display parts 3a to 3d when viewed from the front can be made equal to each other as an average value. As shown in FIG. 5(e), there was a large difference between bright and dark areas.

When displaying a display pattern consisting mainly of lines such as characters as shown in Figure 4(a), this difference did not become a problem, but when using a light shutter function element such as a liquid crystal display element, a planar When using something that opens and closes a shutter, the brightness difference and brightness unevenness are fatal.

The present invention was made in order to solve such problems, and an object of the present invention is to obtain a surface illumination device that can obtain relatively arbitrary uniform brightness for each display portion.

[Means for solving problems]

In the area illumination device according to the present invention, the light diffusive treatment applied to the rear (back) surface of the transparent substrate is composed of a plurality of regions, and in each region, the lower the light intensity within the transparent substrate, the higher the light intensity. It is designed to have a degree of optical expansion.

[Effect]

In this invention, in the light diffusivity treatment, the lower the light intensity within the transparent substrate, the higher the light diffusion is, and conversely, the higher the light intensity within the transparent substrate, the lower the light diffusion is. Light with relatively uniform intensity is emitted forward in each area.

〔Example〕

Embodiments of the surface illumination device of the present invention will be described below with reference to the drawings. FIG. 1(a) is a plan view of one embodiment, FIG.
b) is a sectional view thereof. This figure 1 (a), figure 1 (
In both figures (b), the same parts as in FIGS. 4(a) and 4(b) are given the same reference numerals and explained.

In both FIGS. 1(a) and 1(b), reference numeral 1 denotes a transparent substrate made of K such as an acrylic plate. This transparent substrate 1
A light source 2 is disposed near the end face of a hole formed in the center of the hole.

A display board 3 is disposed on the front surface of the transparent substrate 1. The display board 3 includes translucent display parts 3a to 3d such as liquid crystal display elements.
have.

Between this display panel 3 and the transparent substrate 1, a light diffusing and transmitting plate 3x is provided.
The light diffusing and transmitting plate 3x1 is made of a milky white acrylic plate or the like.

Further, the light emitted from the rear surface or side surface of the transparent substrate 1 is reflected by a reflecting plate 4, and this reflecting plate 4 is made of white resin or the like.

Reference numeral 5 denotes a holding plate that holds the transparent substrate 1, the light source 2, etc., and is made of a printed circuit board that incorporates a drive circuit for controlling the liquid crystal display element as the display plate 3.

The transparent substrate 1 has a plurality of regions facing the display portions 3a to 3d of the display panel 3, each of which is provided with light diffusive treatments 1a to ld, in which the degree of light expansion increases as the internal light intensity decreases. It is strained. In particular, the brightness of the display area 3C of the display pattern of the display board 3 shown in FIG.

In order to make the display more conspicuous by increasing the brightness of 3b and 3d, for example, white paint is printed with gradually changing area density as shown in Fig. 2(b). The light diffusivity shown in Figure (e) is obtained in each part.

Next, the operation of one embodiment of the present invention configured as described above will be described. A part of the light emitted from the light source 2 enters the transparent substrate 1 from the end face of the hole in the center and propagates inside. On the way, when the light reaches the light diffusive treatments 1a to 1d, a portion of the light is diffused and emitted forward.

A part of the light emitted to the front is reflected by the light diffusing and transmitting plate 3x, and a part of the light emitted to the rear is reflected by the reflection plate 4. As a result, the light intensity inside the transparent substrate 1 becomes 2- K as shown in figure (d).

Therefore, in the same way as the operation explanation of the conventional example, as shown in FIG. 1(b),
The light intensity, that is, the brightness, which passes through the display panel 3 shown in FIG. When viewed from the front of the display portions 3a to 3d of the display panel 3, the brightness becomes blurred due to the light diffusing and transmitting plate 3x, as shown in FIG. 2(e).

This brightness distribution is the display area 3c of the display board 3 that you want to stand out.
However, the area is significantly larger than other areas, and there is no large difference within each display area as in the conventional case.

In the above embodiment, the light diffusing and transmitting plate 3 The back surface or the surface of the transparent substrate 10 may be directly printed, or the surface may be textured.

Naturally, the areas other than the display area K may be selectively subjected to light reflective treatment in order to effectively reflect light toward the transparent substrate 1 side.

In addition, in the above embodiment, in order to make the display pattern of a specific display part stand out, the luminance distribution was shown as an example in which the light diffusivity was relatively increased in a part corresponding to that display part. It goes without saying that it is also possible to make each part have the same brightness. Examples thereof are only shown in FIGS. 3(a) to 3(e).

The light diffusivity treatment was performed by applying white paint printing with varying areal density (with a distribution), and a method of varying the degree was shown, but when the density was changed, El!
Of course, it is also possible to provide fl.

〔Effect of the invention〕

As described above, the present invention is characterized in that a light diffusive treatment is applied to the back surface of a transparent substrate corresponding to a plurality of display areas in such a way that the degree of light diffusion increases as the internal light intensity decreases. As a result, the brightness of the display pattern of each display part of a display/board having a plurality of display parts can be uniform within each display part, and can have an arbitrary relative brightness level. Along with this, there is an effect that a high degree of planar display can be achieved using a liquid crystal display element or the like.

[Brief explanation of drawings]

FIG. 1(a) is a plan view of an embodiment of the surface illumination device of the present invention, FIG. 1(b) is a sectional view of the same top surface illumination device, and FIG. 2 is for explaining the operation of the same top surface illumination device. Figure 3 is a diagram showing light diffusion, brightness, etc., for explaining the operation of another embodiment of the surface illumination device of the present invention. Figure 4 (JL) is a diagram showing light diffusion, brightness, etc. is a plan view of a conventional surface illumination device, and FIG. 4(b) is a sectional view of the surface illumination device of FIG. 4(a).
FIG. 5 is a diagram showing light diffusion, brightness, etc. for explaining the operation of a conventional surface illumination device. 1... Transparent substrate, 1a to 1d... Light diffusive treatment, 2
...Light source, 3. Display board, 3a to 3d. Display portion, 4. Reflection plate, 5. Holding plate. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] A display board having a translucent display part, which is arranged on the back side of the display board and consists of a plurality of regions facing the display part, and each region has a light diffusivity that increases as the light intensity decreases. A surface illumination device comprising a transparent substrate subjected to a diffusion treatment, a light source disposed in the center of the transparent substrate, and a light diffusing and transmitting plate disposed between the transparent substrate and a display plate.