JPH06265731A - Plate body for surface emission - Google Patents

Abstract

PURPOSE:To obtain a plate body for surface emission with structure to uniformly and efficiently emit light from a light source extending over the whole surface by molding a large number of shallow holes whose capacity is increased gradually in proportion to separate distance from the light source according to a prescribed pattern. CONSTITUTION:Such constitution that a large number of shallow holes 2 whose capacity can be increased gradually in proportion to the separate distance from the light source are formed on the whole plane of one plane of a transference substrate 1 according to the prescribed pattern is employed. The plate body for surface emission is formed in such a way that a part to expedite light that is the shallow holes 2 is formed by an extremely elaborate processing means as designed more than anything else. As a result, when the shallow holes 2 are molded integrally with the injection molding stage of the transference substrate 1, the change of the capacity of the shallow hole 2can be applied by elaborate processing almost near to stepless adjustment, and an extremely stable emitting state can be provided, which increases an effect more than ever.

Description

Detailed Description of the Invention

[0001]

It is an object of the present invention to provide a surface emitting plate for use in a display device such as a liquid crystal backlight, a display stand, or a display panel of a certain type, which requires illumination from the entire back surface of the display section. Yes, in particular, light sources such as fluorescent lamps and cold cathode discharge tubes are arranged on the side surface of the transparent substrate,
It is an object of the present invention to provide a surface emitting plate having a novel structure capable of uniformly and efficiently emitting light from the same light source over the entire surface.

[0002]

2. Description of the Related Art A liquid crystal display device is indispensable as a display unit for various consumer equipment such as portable and vehicle-mounted televisions, notebook type personal computers, laptop type engineering workstations and monitor televisions, office automation equipment and industrial equipment. It is an important device part that cannot be done. In response to today's social demands such as visualization of the home due to changes in lifestyle, individual access to various information media, social demand for large-screen display for high-definition TV, social energy saving, etc. There is a great interest in this liquid crystal display device, that is, a liquid crystal display element (LCD).

This is because a new display mechanism such as a PDP (plasma display) or an EL (electroluminescence), which is currently under development and research, requires a considerable amount of time to obtain a high brightness and a full color. Prediction that the drawbacks such as being quite expensive will not be resolved for a while, etc. are also taken into consideration, and it is possible to drive LSI with low voltage and low display power operation of LCD, and it is possible to realize lightweight and flat panel. Is capable of high-capacity, high-definition display, full-color display,
As a result of the high qualities such as high brightness and the ability to display on a large screen, the structure is extremely advantageous in realizing various consumer and industrial equipment that will be needed in the future. Since the functions are included, various researches and developments for further strengthening their structures and functions have been advanced, and many have already been put into practical use.
Each of them has fulfilled its intended purpose.

This liquid crystal display device is also a CRT (Cathode Ray Tube) in view of its image quality due to the limitations of the liquid crystal itself.
Since it lags behind that of other display devices, an effective solution for that part is needed, and one solution has been a liquid crystal display device with a backlight mechanism. That is, the backlight mechanism functions to uniformly increase the illuminance from the back surface of the display unit of the liquid crystal display device to the entire screen, and how to realize a bright screen without unevenness It is the most important key to the backlight mechanism, and various mechanisms have been proposed or actually adopted to achieve the purpose.

The method is roughly classified into a method in which light from a light source is received by a reflecting plate having a devised shape and is uniformly reflected in a predetermined direction, that is, the entire back surface of a display screen (for example, Japanese Patent Laid-Open No. 62-284307). Or the like in which a U-shaped or other bent light source is arranged on the back surface of the screen (for example, JP-A-63-1).
A method in which light from a light source almost directly reaches the back surface of a display screen by using a space as a medium, as represented by the inventions disclosed in Japanese Patent No. 25975). The light from the light source placed next to the transparent substrate is used by utilizing the property that the light from the transparent substrate is guided into the transparent substrate and the light transmission or non-transmission is determined by the critical angle at the interface between the material and air. Can be divided into a method of irradiating one side of the transparent substrate, that is, the back side of the display screen of the display device, that is, a method of leaving the transparent substrate itself in a situation where it emits light.

In the former method, the backlight mechanism itself becomes a large scale, which is not suitable for miniaturization, but it has a fatal weak point, and it is not suitable for mass production. However, the latter method is the one that is most frequently used and has been proposed a lot, except for such devices. In this latter mechanism, the thickness of the transparent substrate is changed in consideration of the distance from the light source,
A method to evenly disperse and emit light on a predetermined surface side (for example,
The invention disclosed in Japanese Patent Application Laid-Open No. 2-272487 is also included, but since the thickness is changed, the process of manufacturing and processing the one according to the display screen size is complicated, and the maximum thickness is also included. Since the thickness of the part becomes thicker and it is also disadvantageous for downsizing, we are trying to realize the surface emitting plate body by exclusively using the transparent substrate of the same thickness. That is the current situation.

The method that is currently in the mainstream as a means for emitting light from a transparent substrate of the same thickness is to use a volatile or ultraviolet curable white ink containing reflective particles on the surface of the transparent substrate from a light source. It is printed in a special pattern that increases its density in proportion to the separation distance of
The diffuse reflection of light by the white ink causes the light from the light source to be emitted to the back side of the display screen.
Proposals that have been variously improved and devised with the intention of making the light emission phenomena uniform and uniform, for example, JP-A-3-5725.
As in the inventions disclosed in Japanese Laid-Open Patent Publication No. 3-6525 and Japanese Patent Laid-Open No. 3-6525, an ink print layer is formed on the back side of the transparent substrate, not on the front side, and a finely textured surface is formed on the front side. The light from the light source is reflected on the ink print layer for the time being, and unevenness generated in the ink print layer is corrected by the uneven processed surface on the transparent substrate surface side, as seen in the one that is corrected. It is possible to extract those having various configurations.

However, as is strangely shown in the above-illustrated invention, the method itself in which the light from the light source is guided into the transparent substrate and reflected and emitted by the speckled ink printed with the special pattern is provided. Due to the limitations of ink printing technology and problems with the properties of the ink itself, it is almost technically impossible to make the spotted ink shape extremely accurate (preventing bleeding and preventing print leakage). Due to the fact that it is nearly impossible, and as a result, it is not possible to make fine print adjustments that change the size of the spots that change according to the separation distance from the light source to a nearly stepless state, etc. At the site where the method using this ink printing layer is currently used, how to improve the printing accuracy, or how to optimize the ink material, etc. Said efforts are not continued to be made, it completed the technical means for them is a fact is that it is not yet be reached anywhere.

In order to cope with the above situation, the present invention has been developed and studied for many years as a person involved in the manufacture of a surface emitting plate for a backlight mechanism similarly used in a liquid crystal display device. As a result of continuing the above, finally, the present invention succeeded in realizing an extremely effective, practical and novel surface emitting plate body having a configuration as described in detail below. That is, the surface emitting plate of the present invention is basically proportional to the separation distance from the light source on the entire surface of one side of the transparent substrate from the side edge which is the incident side from the light source to the other side edge. The gist of the present invention is to form a large number of shallow holes, which are not necessarily directly proportional to each other) and gradually increase in volume according to a predetermined pattern.

As the transparent substrate, a conventionally known acrylic transparent plate or other appropriate material can be adopted. It is developed by printing a predetermined pattern, that is, ink spots on the entire surface of one side of the transparent substrate. The pattern that is the same as or different from the pattern that is present, or a pattern that has been specially developed for this invention. Basically, the pattern gradually increases in proportion to the distance from the light source. A large number of shallow holes are formed in a pattern regulated so as to increase the volume.

As a means for forming the shallow holes, it is possible to adopt a sandblast method or the like, but this requires a masking step on the surface of the transparent substrate, and therefore, the same drawbacks as those of the conventional ink print layer forming means occur. In addition, the masking printing process itself has more steps than the conventional method of forming an ink printing layer, which is disadvantageous in the manufacturing process and cannot be a desirable molding means. Moreover, although cutting by a drill can be performed, problems such as cutting accuracy need to be solved. A preferred method for forming shallow holes in the present invention is in the process of manufacturing a transparent substrate, that is, when the transparent substrate is formed by injection molding, at the time of injection molding, or when the transparent substrate is formed by hot rolling. If so, during hot-roll forming, shallow holes with a predetermined pattern will be integrally formed on the transparent substrate to be formed. Is formed in advance, and when a transparent substrate is formed, a forming means is adopted which becomes a transparent substrate to which a predetermined pattern is already applied.

The structure in which a large number of shallow holes to be formed gradually increase in volume in proportion to the separation distance from the light source according to a predetermined pattern is such that the light from the light source guided in the transparent substrate is It is necessary to correct the property that the illuminance is gradually attenuated as it moves away from the light source as a result of repeated reflection, bending, and transmission in the transparent substrate, and to make the illuminance as uniform as possible over the entire transparent substrate. However, the conventional ink print layer forming means is comparable to the configuration in which the diameter of the ink spots is gradually increased and corrected. In the following, some typical examples thereof will be described. Is to explain

[0013]

Example 1 First, the first case is shown in a vertical cross-sectional view in which a part of FIG. 1 is omitted. The shallow holes 2, 2, ...
The change in the volume of is realized only by the change in the aperture R. Therefore, the depth D of the hole is, for example,
Limit to an appropriate value within the range of 0.1 to 0.5 mm (optimally around 0.3 mm). The ratio of the change in the aperture R (change within the range of 0.01 to 2 mm in the normal practical range), that is, R
The value of r of n-R (n-1) = r is such that the forming accuracy of the diameter of the shallow hole 2, 2, ... forming the die plate (not shown) is extremely high. Considering that it can be carried out in a precise manner, it is practically possible to make the difference value as close to 0 as possible, which changes almost steplessly. The hole shape of shallow holes 2, 2, ...
Compared with the method of arranging the spot-shaped shapes (contour shape) by the ink print layer, the accuracy is remarkably accurate.

[0014]

[Embodiment 2] In the example shown in FIG. 2, the change in the volume of the shallow holes 2, 2, ... Is realized not by the change in the diameter R of the hole but by the change in the depth D of the hole. As in the case described above, the change in the depth D of the hole is almost stepless, that is, the depth d of adjacent Dn-D (N-1) = d is as close to 0 as possible. Is feasible as The diameter R of the shallow holes 2, 2, ... In this embodiment is shown as being restricted to a value of about 1 mm, but of course it is not limited to this value, and the depth of the hole to be changed. In relation to D,
Care must be taken to adopt the optimal one that provides a certain amount of brightness evenly.

[0015]

[Third Embodiment] The final example is a combination of the first and second embodiments, as can be understood from the overall perspective view of FIG. 3 and the enlarged vertical sectional view in which a part of FIG. 4 is omitted. Shallow hole 2,
The change in the volume of 2, ... Is realized by changing both the diameter R and the depth D of the hole in accordance with a fixed relationship, and the degree of change is almost the same as in the above-mentioned embodiments. It goes without saying that it is also possible to make it close to a step change.

It should be noted that the sizes of the shallow holes 2, 2, ...
This is exaggeratedly expressed in relation to the thickness of the transparent substrate 1, and the shallow holes 2, 2, ... Based on the technical idea of the present invention.
Has no effect on the size of. In addition, the shape of the inner peripheral surface of the shallow holes 2, 2, ... Is displayed as being smooth, but it may be a matte surface that has been appropriately "textured", or a fine streak surface or the like. Of course, the planar shape and sectional shape of the hole are not limited to those shown in these embodiments, and can be appropriately selected.

[0017]

[Operation] The surface emitting plate body of the present invention obtained as described above is disposed in the vicinity of the rear surface of the display portion of the liquid crystal display device, and is a cross-sectional perspective view with a part of FIG. 4 cut away. As shown in, the smaller volume of the shallow holes 2, 2, ... (It is not clear because there is little change on the display,
A fluorescent lamp or other light source L is arranged on the side surface (on the left side in the drawing), while it is also used in the case of the surface emitting plate body on which the ink print layer is formed on the back surface of the surface emitting plate body. The reflecting plate 3 is arranged so as to cover each surface other than the light emitting surface and the side surface on the light source side, and a light diffusing thin plate 4 made of polycarbonate or the like is additionally provided on the light emitting surface side. Depending on the case, it is possible to form the entire surface of the light emitting surface in advance as a satin finished surface.

When the light source L is turned on and light is made incident on the surface emitting plate body of the present invention thus arranged, the light from the light source L is guided into the transparent substrate 1. At the same time, at the interface with the air of the transparent substrate 1, the light traveling at an angle smaller than the critical angle is repeatedly reflected and refracted on the surface, and the light exceeding the critical angle is emitted to the outside of the transparent substrate 1. , The transparent substrate 1 is emitting light, but the shallow holes 2, 2, ... Arranged in a predetermined pattern that gradually increases the volume of the function of promoting and promoting this light emitting state. Will be shared.

That is, when light which is repeatedly reflected and refracted in the transparent substrate 1 hits the shallow holes 2, 2, ... Peripheral surface from various angles, it is substantially in the peripheral surface, particularly the light emitting surface of the transparent substrate 1. On the planes that are orthogonal to each other, most of the light far exceeds the critical angle of the interface, so that the light is emitted from the transparent substrate 1 and emitted from the same place, that is, a so-called light emitting state. The amount of light emitted from the shallow holes 2, 2, ... Is determined by the area of the peripheral surface of the shallow holes 2, 2 ,. It is possible to correct a phenomenon in which the light emitting state of the light emitting surface of the substrate 1 becomes gradually darker due to the distance from the light source L arranged on the side edge of the transparent substrate 1, and the entire light emitting surface is made substantially uniform. be able to.

The change in the area of the peripheral surface of the shallow holes 2, 2, ... Particularly, the portion intersecting the light emitting surface is the change of the shallow holes 2, 2 ,. , Shallow hole 2,2
By the means shown in the first embodiment for temporarily increasing the area of the plane shape while keeping the depth constant, the shallow holes 2, 2 ,.
By the means shown in Example 2 in which the diameter of the planar shape of the planar shape is kept constant and only the depth of the shallow holes 2, 2, ... Is temporarily increased, the area and the depth of the planar shape are combined. Both of them are temporarily increased by the means shown in the third embodiment, and the rate of these changes is such that the transparent substrate 1 and the transparent substrate 1 are integrally molded in a mold at the same time. , It is also possible to make it almost stepless.

[0021]

[Effects] Compared with the conventional ink-printing layer-forming device, the surface-emitting plate of the present invention realized as described above, first of all, is a portion that promotes light emission, that is, a shallow hole 2. 2, ... (the portion corresponding to the spots formed by the conventional ink print layer) is formed as calculated by extremely sophisticated processing means, and as a result, they are slightly uneven and the light emission state is uneven. It has a great feature that it can be superior to the conventional ones that tend to become something like this. In particular, as described above, when the shallow holes 2, 2, ... Are integrally molded at the injection molding stage of the transparent substrate 1, the change in the volume of the shallow holes 2, 2 ,. Fine processing is also possible, and the inconvenience that the conventional one had to make the change technically large and expressed a stripe pattern in the light emission phenomenon was wiped out completely and it is very stable and clean. Since a different light emission state can be realized, it can be made even more effective.

Further, in the present invention, the portion for promoting the light emission is the shallow holes 2, 2, ... And the structural portion for attenuating the light from the light source L like the ink print layer of the conventional one. Since it does not have the light, the light from the light source L can be efficiently emitted in the transparent substrate 1, a brighter and more uniform light emitting state can be realized, and in addition, unevenness in printing causes the finished product to be Yields deteriorate (usually about 10% become defective products), which definitely eliminates the disadvantages of the previous products that had to be uneconomical, enabling extremely efficient manufacturing and processing. Besides having the advantage of
Since the printing process itself is not required and the number of manufacturing processes can be reduced, the remarkable effect of being extremely economical as a whole can be exhibited.

As described above, the surface emitting plate body of the present invention is
It is excellent in terms of light emission efficiency and homogenization of light emission state over the entire surface of light from a light source, and it has the operational effects that were difficult to achieve by the previous ones such as improving manufacturing efficiency and eliminating quality unevenness. Therefore, it is expected to be highly evaluated as an important display part component of a liquid crystal display device, which is expected to be further popularized.

BRIEF DESCRIPTION OF THE DRAWINGS The drawings show some of the representative embodiments of the invention.

FIG. 1 is a vertical sectional view showing a typical embodiment of a shallow hole whose volume is gradually increased.

FIG. 2 is a longitudinal sectional view showing another typical embodiment of the shallow hole whose volume is gradually increased.

FIG. 3 is a vertical cross-sectional view showing still another representative embodiment of the shallow hole whose volume is gradually increased.

FIG. 4 is a partially exploded perspective view of a main part of a backlight device using the present invention.

[Explanation of symbols]

 1 Transparent substrate 2 Shallow hole 3 Reflector 4 Light diffusion thin plate D Shallow hole depth L Light source R Shallow hole diameter

Claims (4)

[Claims] 1. A shallow hole is formed on the entire surface of one side of a transparent substrate, the volume gradually increasing in proportion to the separation distance from the light source from the side edge which is the incident side from the light source to the other side edge. A surface emitting plate body formed by molding a large number according to a predetermined pattern. 2. The surface emitting plate according to claim 1, wherein the change in the volume of the shallow hole is realized by a change in the aperture. 3. The surface emitting plate according to claim 1, wherein the change of the volume of the shallow hole is realized by the change of the depth of the hole. 4. The surface emitting plate according to claim 1, wherein the change in the volume of the shallow hole is realized by changing both the diameter and the depth of the hole according to a fixed relationship.