JPH0667027A - Surface illuminator - Google Patents

Abstract

PURPOSE:To reduce unevenness in luminance and to make the device thin and light weight concerning the surface illuminator carrying out uniform illumination on the surface. CONSTITUTION:Fluorescent tubes 23a and 23b are disposed in a reflective mirror 22 and a light control plate 24 and a diffusion plate 25 are provided in this opening part. A grid state transmission reflection pattern is formed by the light control plate 24 with a surface-reflective and circular-shaped cross-sectional wire rod 24a as a textile structure. In this case, the grid state pattern immediately over the fluorescent tubes 23a and 23b are formed to be dense.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface lighting device which illuminates a surface uniformly.

In recent years, for example, with the colorization of liquid crystal display devices and the downsizing of notebook type OA equipment, there has been a demand for higher brightness, thinner and lighter surface mounted illumination devices. Therefore, it is necessary to reduce the unevenness in brightness to achieve high brightness and to achieve thinning and weight reduction.

[0003]

2. Description of the Related Art FIGS. 7 and 8 are views for explaining a conventional surface lighting device.

The surface illuminator 11 _A shown in FIG. 7A is of a so-called direct type, in which, for example, two fluorescent tubes 13 a and 13 b are arranged in a box-shaped reflecting mirror 12. A lighting curtain 14 made of a resin sheet is provided on the opening of the reflecting mirror 12. Further, a diffusion plate 15 is provided on the lighting curtain 14.

The lighting curtain 14 is shown in FIG.
As shown in, PET (polyethylene terephthalate)
Aluminum reflection points 14b are formed in a dot pattern on a resin film 14a in a predetermined pattern (densely arranged immediately above the fluorescent tubes 13a and 13b).

That is, as shown in FIG. 7C, in the surface lighting device 11 _A , the highest brightness is immediately above the fluorescent tubes 13a and 13b. Therefore, the aluminum reflection points 14b are arranged at a high density in this part. Increase the amount of reflection. In addition, since the arrival point of the light becomes far in other parts and the brightness becomes low, by reducing the aluminum reflection points 14b at a low density and increasing the transmission amount, the light is made uniform on the light surface (diffusion plate 15). It is designed to have brightness.

On the other hand, the surface lighting device 11 _B shown in FIG.
Is a so-called edge light type, in which a light diffusing plate 18 is provided on one surface of the light guide plate 17 in which light sources (fluorescent tubes) 16a and 16b are arranged at both ends of a side, and a reflecting plate is provided on the other surface. 19 is provided. And the fluorescent tubes 16a, 16b
The reflectors 20a and 20b are provided on the outer periphery of the.

On the surface of the light guide plate 17 facing the reflection plate 19, as shown in FIG. 8B, a print film is formed in which print dots 19a having a diffuse reflection characteristic are formed in a dot pattern in a predetermined pattern. Has been done. The printed points 19a having a predetermined pattern have a function of emitting the light propagating inside the light guide plate 17 to the outside, and are formed such that the area of the printed points 19a in a unit area increases as the distance from the fluorescent tubes 16a and 16b increases. To be done.

The surface illuminator 11 _B of this type has the fluorescent tube 1
The lights from 6a and 16b are substantially condensed and incident on the side surface of the light guide plate 17 by the reflectors 20a and 20b, and propagate in the light guide plate 17 by total reflection. At this time, the light striking the printing point 19 a is diffused and reflected on the other surface of the light guide plate 17 and is emitted to the outside of the light guide plate 17.

That is, the area of the printing point 19a per unit area on the printing surface of the light guide plate 17 is defined by the fluorescent tubes 16a,
The brightness can be made uniform on the emission surface of the diffusion plate 18 by appropriately setting it according to the distance from 16b.

[0011]

However, in the surface lighting device 11 _A shown in FIG. 7, it is necessary to strictly determine the light amount control with respect to the position of the lighting curtain 14, and the positional deviation of the used members such as the light source. When occurs, the amount of light at a predetermined position changes, which causes a large unevenness in brightness on the light emitting surface. Further, the lighting curtain 14 is substantially adhered to the diffuser plate 15, and the diffuser plate 15 having a high diffusing property, that is, thick and having low light transmittance is used so that the reflection point 14a cannot be recognized from the light emitting surface side. Therefore, there is a problem that high brightness and thinness cannot be achieved.

On the other hand, the surface illumination device 11 _B shown in FIG. 8 condenses the light sources 16 a and 16 b in one direction and emits the light through the light guide plate 17, so that the brightness is lowered and most of the devices are guided. Since it is occupied by the optical plate 17, it is difficult to reduce the weight.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a surface illuminating device which reduces luminance unevenness and is thin and lightweight.

[0014]

SUMMARY OF THE INVENTION The above object is to provide a surface illuminating device which allows light from a light source to be incident on a diffuser plate by controlling the amount of transmitted light by a transmissive reflection pattern on a light control plate and to be emitted from the entire surface of the diffuser plate. In the above, the transmission / reflection pattern of the light control plate is formed in a grid shape with different densities, and the grid-shaped transmission / reflection pattern of the light control plate is appropriately formed into a woven structure of a wire rod having a circular cross section for surface reflection. It is solved by forming.

It is also possible to solve the problems by providing the above-mentioned light control plate in a plurality of stages at a predetermined angle with respect to the optical path from the light source and letting the reflected light of each stage enter the diffusion plate.

[0016]

As described above, the transmission / reflection pattern of the light control plate is changed to
It is formed in a lattice shape with different densities. In this case, the grid-like transmission / reflection pattern is formed by using a wire material having a surface-reflection circular cross section as a woven structure.

Thus, the amount of transmitted light of the light from the light source is controlled by the transmissive / reflecting pattern having different grating densities of the light control plate. In this case, when the pattern is formed by forming a wire material having a surface-reflective circular cross section into a woven structure, the light impinging on the pattern is not totally reflected but only a part is reflected and the other is diffused due to the shape. It will be incident on the diffusion plate.

Therefore, it is possible to eliminate uneven brightness while maintaining high brightness without requiring accuracy in mounting a light source or the like.

Further, a plurality of light control plates are provided at a predetermined angle in the optical path from the light source, and the reflected light of each stage is made incident on the diffusion plate. That is, the light control plate also plays the role of a light guide plate, and it is possible to achieve thinning and weight reduction.

[0020]

FIG. 1 is a block diagram of the first embodiment of the present invention. In FIG. 1, the surface lighting device 21 includes a box-shaped reflecting mirror 2
Two fluorescent tubes 23 a and 23 b are arranged as light sources in the light source 2, and a light control plate 24 is provided at the opening of the reflecting mirror 22. Then, the diffusion plate 25 is positioned on the light control plate 24.

For example, the reflecting mirror 22 is a box-shaped one made of an aluminum material (thickness: 0.5 mm) with white coating on the inner wall, and the fluorescent tubes 23a and 23b are cold cathode fluorescent tubes having a diameter of 8 mm. Is used.

Here, FIG. 2 shows a diagram for explaining the light control plate of FIG. 2 (A) and 2 (B), the light control plate 24 is formed by forming a wire material 24a, which has a diameter of 0.5 mm and is plated with aluminium, on the surface of the metal fiber into a woven structure in a lattice shape. Then, for example, it is coated with acrylic resin or the like to prevent deformation such as bending. This grid-shaped wire 24 a becomes a transmission / reflection pattern of the light control plate 24.

Further, as a transmission / reflection pattern of the light control plate 24, a density for reducing the amount of transmitted light, that is, a dense portion 26a is formed at a portion immediately above the fluorescent tubes 23a and 23b, and
Density at which the amount of transmitted light is large at a distant portion, that is, a sparse portion 26b
Is formed. That is, the sparse / dense state of the transmission / reflection pattern is appropriately set according to the distance relationship with the fluorescent tubes 23a and 23b.

Therefore, FIG. 3 shows a diagram for explaining the dimming principle of FIG. 2, which will be described together with FIG.

The above-mentioned surface lighting device 21 is, for example, the fluorescent tube 2
A part of the light from 3b directly reaches the light control plate 24, and the other light reaches the reflecting mirror 22 and the other fluorescent tube 23a. The light that directly reaches the light control plate 24 changes in brightness according to the distance, and becomes brighter as it gets closer to the fluorescent tube 23b,
The light reaching the reflecting mirror 22 and the other fluorescent tube 23b is reflected and diffused, and the reaching distance to the light control plate 24 becomes large and the brightness becomes low as the distance from the fluorescent tube 23b increases.

At this time, as shown in FIG.
Part of the light striking the wire 24a forming the transmissive reflection pattern is reflected inside the reflecting mirror 22, and part of the light is diffused by changing the optical path and is incident on the diffusion plate 25.

As described above, the light reaching the light control plate 24 has higher brightness as it is closer to the fluorescent tube 23b and lower brightness as it is farther away. That is, the closer it is to the fluorescent tube 23b of the light control plate 24, the denser it is, that is, the transmitted light amount is small and the reflected light amount is large.
Since the amount of transmitted light is large and the amount of reflected light is small as the distance from 3b increases, the light passing through the light control plate 24 and emitted from the diffusion plate 25 is uniform on the light emitting surface.

As a result, the diffusion plate 25 can be made thinner, and accordingly, the surface lighting device 21 can be made thinner, and the transmittance of the diffusion plate is improved, so that higher brightness can be realized.

Here, FIG. 4 shows a diagram for explaining another structure of FIG. In FIG. 4, the wire 24b forming the transmission / reflection pattern of the light control plate 24 is obtained by coating the surface of the PET resin fiber 33 with the aluminum thin film 32 and then recoating it with the PET resin coating 31.

Next, FIG. 5 shows a block diagram of an application example of the first embodiment. FIG. 5 shows a liquid crystal display device 41 in which the above-mentioned surface lighting device 21 is mounted. A liquid crystal panel 42 is provided on the diffusion plate 25 of the surface lighting device 21, and these are supported by the support frame 4.
It was fixed at 3.

The liquid crystal panel 42 is driven by the control unit 45 such as a computer and the surface lighting device 2
The wire rod 24 a of the first light control plate 24 is connected to the zero reference potential portion of the control unit 45. By setting the wire 24a to the zero reference potential, electromagnetic waves and high frequency currents generated from the surface lighting device 21 and the liquid crystal display device 41 are shielded.

Next, FIG. 6 shows a block diagram of a second embodiment of the present invention. The surface lighting device 51 in FIG. 6A is of an edge light type, and fluorescent tubes 23a and 23b as light sources are provided on opposite sides of a rectangular space formed by the reflection plate 52 and the diffusion plate 53. The reflectors 54a and 54b are provided on the outer circumferences of the fluorescent tubes 23a and 23b.

In the space between the reflecting plate 52 and the diffusing plate 53, a plurality of dimming plates 55 are provided at an angle of about 45 ° in the direction of the reflected light toward the diffusing plate 53.

As shown in FIG. 2, the light control plate 55 may have a transmission / reflection pattern formed of a wire material in a woven structure in a lattice pattern, and as shown in FIG. 6 (B), for example, has a thickness of 1 mm.
Aluminum is vapor-deposited in a grid pattern on the surface of the transparent acrylic plate 55a as a reflective film 55b.
It may be coated with c to form a multilayer structure.

Further, the light control plate 55 at each stage is used for the fluorescent tube 23.
As the distance from a and 23b increases, the distance between the lattice patterns becomes smaller and the lattice patterns are densely formed. Thereby, the amount of reflected light is increased.

In this embodiment, one light control plate 5 is used.
Although it is not essential to adjust the amount of reflected light depending on the position within 5, it may be appropriately adjusted depending on the state of the light emitted from the light source unit by the configuration of the reflectors 54a and 54b.

The surface lighting device 51 as described above is provided with the respective light control plates 5.
Although the light reaching 5 is reflected toward the light emitting surface of the light control plate 55, a part of the light is transmitted and reaches the light control plate 55 at the next stage, and is repeatedly reflected and transmitted.

As a result, the light control plate 55 causes the fluorescent tubes 23a,
Since the amount of reflected light is adjusted according to the distance from 23b, the light emitted to the light emitting surface is uniform over the entire light emitting surface.

Furthermore, the diffusion plate 5 is provided on the light emitting surface of the light control plate 55.
Since 3 is arranged, the uniformity of luminance is further improved and the light control plate 55 is hidden.

As a result, the space occupied by the conventional resin plate can be replaced with a few light control plates 55, so that the weight can be greatly reduced.

[0041]

As described above, according to the present invention, the transmission / reflection patterns of the light control plate are formed in a grid shape having different densities, or the light control plates are provided in a plurality of stages at a predetermined angle with respect to the optical path from the light source. As a result, it is possible to reduce luminance unevenness and to reduce the thickness and weight.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first embodiment of the present invention.

FIG. 2 is a diagram for explaining the light control plate of FIG.

FIG. 3 is a diagram for explaining the light control principle of FIG.

FIG. 4 is a diagram for explaining another structure of FIG.

FIG. 5 is a configuration diagram of an application example of the first embodiment.

FIG. 6 is a configuration diagram of a second embodiment of the present invention.

FIG. 7 is a diagram for explaining a conventional surface lighting device.

FIG. 8 is a diagram for explaining a conventional surface lighting device.

[Explanation of symbols]

 21, 51 Surface lighting device 22 Reflector 23a, 23b Fluorescent tube 24, 55 Light control plate 25, 53 Diffuser plate 26a Dense part 26b Sparse part 41 Liquid crystal display device 42 Liquid crystal panel 43 Support frame 45 Control part 52 Reflector plate

Claims (6)

[Claims] 1. The light from a light source (23a, 23b) is made incident on a diffuser plate (25) by controlling the amount of transmitted light by a transmissive reflection pattern on a light control plate (24), and emitted from the entire surface of the diffuser plate. A surface lighting device, characterized in that the transmission / reflection pattern of the light control plate (24) is formed in a lattice shape with different densities. 2. The grid-shaped transmission / reflection pattern of the light control plate (24) has a surface-reflecting wire rod (24) having a circular cross section.
2. The surface lighting device according to claim 1, wherein a) is formed to have a woven structure. 3. The transmission / reflection pattern of the light control plate (24) is formed at a density that reduces the amount of transmitted light in a portion near the light sources (23a, 23b), and the light source (23).
3. The surface lighting device according to claim 1, wherein the surface lighting device is formed with a density that increases the light amount in a portion far from a and 23b). 4. The light control plate (55) is connected to the light source (23).
The surface lighting device according to claim 1 or 2, wherein a plurality of stages are provided at a predetermined angle with respect to the optical path from (a, 23b), and the reflected light of each stage is incident on the diffuser plate (53). 5. The light control plate (55) is a transparent plate (55).
5. The surface lighting device according to claim 4, wherein a grid-like film (55b) of the transmissive reflection pattern is formed on a). 6. The surface lighting device according to claim 4, wherein the density of the transmission / reflection pattern of the light control plate (55) is different in each of the stages.