JPH079515B2 - Backlight device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight device capable of obtaining illumination light (reflected light) with an evenly distributed illuminance from the entire area of a thin plate.

[0002]

2. Description of the Related Art In recent years, liquid crystal display boards which are being put to practical use are
It adopts a special method that can obtain high resolution, and configures circuits and parts into LSI (Large Scale Integrated Circuit) to make it compact.

[0003]

The liquid crystal having the above structure has the following problems. (1) Although the above liquid crystal has high resolution, it is not easy to obtain uniform illuminance over the entire display surface, and there is a problem that illuminance decreases as the position is farther from the light source of the backlight device.

(2) As a means for enhancing the above-mentioned display function, for example, there is one in which the light of a light source as a backlight is reflected on the back side of a liquid crystal image by a surface-finished matte reflector. Similar to the above, there was unevenness in the illuminance on the display surface, and it was not easy to obtain a sufficiently high illuminance, and an optimal backlight device at low cost could not be obtained. (3) When a fluorescent lamp is used as a light source, the illuminance of the fluorescent lamp is generally high in the central part and low at both ends, so that the light source itself has uneven illuminance and is irradiated onto the front surface of the backlight plate. It was difficult to make the illuminance uniform.

[0005]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention is provided on the back side of a display plate and enables irradiation of illumination light from at least one peripheral side of at least four rounds constituting a backlight plate. A transparent substrate, a light diffusing unit formed on the rear surface of the transparent substrate, and a light source arranged on the peripheral side of the transparent substrate, and the display plate is illuminated by the light emitted from the light source. In the backlight device for illuminating, the light diffusing unit is inversely proportional to the illuminance distribution of the backlight plate by the irradiation light of the light source on the uneven surface formed on the rear surface of the transparent substrate with a size of 2 μ to 3 μ or less. It is characterized in that a dot-like reflection pattern is depicted with a density.

[0006]

When illuminating light is obtained from the backlight plate, when a light source fixed at least on one peripheral edge of the four circumferences is turned on, the illuminating light from this light source is emitted into the backlight plate. According to this aspect, the illumination light traveling in the substrate is diffusely reflected by the light diffusing means by the reflection pattern drawn with the density inversely proportional to the illuminance distribution of the backlight plate by the illumination light of the light source, and is directed to the front face of the backlight plate. Illumination light having an evenly distributed illuminance can be easily and reliably emitted from the entire area of the plate. If the light diffusing means is formed with an uneven surface having a size of 2 to 3 μ or less and the reflection pattern is drawn on the uneven surface, the uneven surface allows the transparent substrate to be seen through from the thickness direction. However, since it is so small that it cannot be visually confirmed, it has no influence on the background.

[0007]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 and 2 show a backlight device according to the first embodiment of the present invention. This backlight device includes a single backlight plate A and the backlight plate A.
Each of the light sources 6 is placed on the four circumferences. First, the backlight plate A, which is the main body of the backlight unit, is constructed as follows. That is, the backlight plate A uses a thin transparent resin substrate 1 such as an acrylic resin plate having a good transmittance as its base material. The front and rear surfaces of the transparent resin substrate 1 are provided with light-transmitting resin coatings 2 and 3 of, for example, a fluorine-based resin having a light refractive index different from that of the substrate 1 as a light reflecting means.

An uneven surface 4 is formed on the rear surface of the transparent resin substrate 1 as described above by applying a pretreatment agent. The uneven surface 4 has a size of 2 μm to 3 μm, which is so small that it cannot be recognized by human eyes, and does not affect the background seen through the transparent resin substrate 1 from the thickness direction.
The uneven surface 4 is provided with the following light diffusing means 5 using a special ink having a good light reflectance. This light diffusing means 5 is a light source 6 which is fixed on the four sides of the transparent resin substrate 1.
From the distribution of the density that is inversely proportional to the distance from
The dot form is provided by known screen printing or the like. Then, the transparent resin substrate 1 provided with the light diffusing means 5 by the above printing is put in a firing furnace (not shown) and subjected to low temperature baking, whereby a single backlight plate A is formed.

In a commonly used fluorescent lamp or the like, the illuminance at the central portion is higher than at both ends thereof. That is, the first
As shown in the figure, the illuminance distribution from each light source 6 on the backlight plate A has a mountain shape B whose base is the light source 6 at each position, and the central zone distant from the light source 6 has the highest illuminance. It becomes a low region C. However, when the light diffusing means 5 is provided on the rear surface of the transparent resin substrate 1, the above-mentioned backlight plate A has dots formed by a distribution of density that is inversely proportional to the distance from the light source 6 fixed on the four circumferences of the substrate 1 and its illuminance. It is provided with a form. Therefore, when the substrate 1 is irradiated with illuminance light from the light sources 6 arranged on the four circumferences during use, the light diffusion means 5 having the highest density distribution is located in the central zone of the low illuminance area C, and this central zone is located. Since the distribution density of the light diffusing means 5 becomes sparse in proportion to the shift from 4 to 4 turns, the light diffusing means 5 at each position has a light reflection phenomenon due to illuminance proportional to the distribution density. The above-mentioned backlight plate A
The reflected light D with an evenly distributed illuminance is obtained from the entire area of the plate A to the front surface of the plate.

At the four peripheral positions of the backlight plate A according to the above embodiment, for example, a dedicated light source 6 such as a fluorescent lamp formed so as to be able to irradiate the irradiation light limited to the peripheral edge of the transparent resin substrate 1 on each side thereof. Are fixed, and the respective light sources 6 and the peripheral edge portions of each side of the transparent resin substrate 1 described above are fixed by encapsulation such as a light source cover (not shown) to form a collective backlight device. It is configured.
A display object such as a liquid crystal plate 7 capable of displaying characters or figures is arranged in parallel at the front position of the backlight device having the above configuration.

The operation of the backlight device in the first embodiment will be described. When each light source 6 fixed on the four sides of the backlight plate A is turned on, the illumination light from each light source 6 is irradiated into the transparent resin substrate 1 from the peripheral edge of each side. In this case, the front and rear surfaces of the transparent resin substrate 1 are provided with translucent resin coatings 2 and 3 having a light refractive index different from that of the substrate 1, respectively, due to the difference in the light refractive index between the two.
The transparent resin coatings 2 and 3 provided on both sides of the transparent resin substrate 1 are totally reflected at the boundary between the transparent resin substrate 1 and the illumination light is not leaked to the outside, and the transparent resin has the same principle as an optical fiber. It is capable of proceeding in parallel with the longitudinal direction of the substrate 1.

The illuminating light emitted from each light source 6 into the transparent resin substrate 1 for each side thereof as described above is transmitted to the transparent resin substrate 1.
It comes into contact with the light diffusing means 5 provided on the concave-convex surface 4 on the rear surface by the distribution of the density inversely proportional to the distance from each light source 6 and the illuminance. At that time, since the surface side of this means 5 is uneven and the material is a special ink having a good light reflectance, the illumination light that abuts on the surface of this means 5 is different at each abutting position. Diffuse reflection occurs along the normal line (not shown) on the uneven surface. Therefore, the irregular reflection causes the means 5 to exhibit a light emission phenomenon.
Moreover, since the irregular reflection is performed by the distribution of the density which is inversely proportional to the illuminance distribution of the backlight plate by the illumination light of each light source 6, the reflection of the uniform distribution of illuminance from the entire area of the plate A to the front surface of the backlight plate A is performed. The light D is easily and surely emitted, and as a result, the backlight plate A is
The liquid crystal plate 7 arranged on the front surface of the above can receive the above-mentioned reflected light D from the entire area behind and can clearly show the liquid crystal display.

[0013]

[0014]

FIG. 3 shows a backlight device according to the second embodiment of the present invention. This backlight device is configured such that the light sources 6 are fixed on the upper and lower peripheral edges of the transparent resin substrate 1, respectively. Therefore, the light diffusion means (not shown) in this embodiment is the same as the one shown in the above-mentioned embodiment.
By providing a dot-shaped reflection pattern with a distribution of density that is inversely proportional to the distance from each light source 6 and the illuminance, reflected light (not shown) due to the even distribution of illuminance is distributed from the entire area of the backlight plate A to the front surface of the backlight plate A. Radiation is emitted easily and reliably, and when a liquid crystal plate (not shown) is arranged on the front side of the backlight plate A, the liquid crystal plate can receive the reflected light from the entire area behind and clearly show the liquid crystal display. It is a thing.

[0016]

EFFECTS OF THE INVENTION Since the present invention is configured as described above, the backlight plate can be changed even if the type, the mounting position, the number of light sources mounted on the backlight plate, or the shape of the backlight plate changes variously. By appropriately designing the reflection pattern according to the illuminance distribution, it is possible to quickly and easily obtain a backlight device having a uniform illuminance distribution. Also, 2
Providing a reflection pattern on micro unevenness of μ to 3μ or less
Therefore, there is no unevenness in illuminance and the entire surface of the transparent substrate.
Backlight device with uniform and sufficiently high illuminance
Obtainable. Therefore, according to the backlight device of the present invention, it is possible to contribute to the improvement of the function of the liquid crystal display at a low cost and to use it as various kinds of backlights.

[Brief description of drawings]

FIG. 1 is a front view showing a backlight device according to a first embodiment of the present invention.

FIG. 2 is a vertical cross-sectional side view of the backlight device according to the first embodiment.

[Figure 3] Front view of the backlight device in the second embodiment
Is.

[Explanation of symbols]

 1 transparent resin substrate 2, 3 translucent resin coating 4 uneven surface 5 light diffusing means 6 light source A backlight plate

Claims (1)

[Claims] 1. A translucent substrate provided on the back side of a display plate and capable of irradiating illumination light from at least one peripheral side of at least four circumferences constituting the backlight plate, and a translucent substrate formed on the rear surface of the translucent substrate. In a backlight device including a light diffusing unit and a light source arranged on the peripheral side of the light transmitting substrate, the backlight unit illuminating the display plate with light emitted from the light source, wherein the light diffusing unit is the light transmitting unit. It is characterized in that a dot-shaped reflection pattern is drawn on a concavo-convex surface formed on the rear surface of the substrate in a size of 2 μ to 3 μ or less at a density inversely proportional to the illuminance distribution of the backlight plate by the irradiation light of the light source. Back light device.