JP3081216B2 - Planar luminous body - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a light scatterer for forming a surface light emitting band or a surface light source in a planar lighting device, a planar backlight, or the like.

(Prior Art) The main ones of the prior art are as follows.

1) Quartz or a multi-component optical fiber in which a part of a polymer clad is finely removed to arrange a large number of fibers to be exposed to light, where the light is emitted from a flat plate surface using a reflector and a light scattering plate.

2) By forming triangular grooves or linear irregularities on the plate or film and irradiating not only the end surface but also the uneven surface of the light transmitting body or the opposite surface with light at an appropriate angle from the outside, a wide area is obtained. Light is scattered over the area and emitted from the surface of this passing object.

3) A device in which a surface is formed by arranging a large number of optical fibers in parallel, and the surface is made uneven, scratched, and actively exposed to light to emit light.

(Problem to be Solved by the Invention) In the above example 1), even if a part of the clad is removed, a new clad layer is formed by air in that part, so that practical exposure (moderate brightness) It is extremely difficult to get Applying such processing to an optical fiber requires high technology and high cost, and thus has a manufacturing difficulty.

In the case of the above 2), the amount of reflected light increases depending on the incident angle of the irradiation light, and it is difficult to obtain a high-luminance planar light-emitting body. In order to maintain a constant angle of incidence, a constant gap is required between the surface and the light source, so that it is difficult to obtain a thin planar light-emitting body.

In the example of the above 3), when continuous irregularities or scratches are made, the attenuation of the entering light is severe, so that the attenuation of the surface light in the traveling direction is large, and it is difficult to obtain a wide surface light-emitting body with uniform luminance. .

The present invention has been made in view of the above problems, and its purpose is to reduce light attenuation due to the traveling direction of light,
An object of the present invention is to provide a high-brightness planar light-emitting body having no variation in illuminance on a surface, and which is easy to manufacture and low in cost.

(Means and Actions for Solving the Problems) The inventor made various studies to achieve the above object, and found that a fine groove was formed on at least one surface of a plate-shaped light guide, and the end face of the light guide was formed. By injecting light substantially along these grooves, it is found that light is uniformly emitted from the entire surface or the back surface of these grooves,
The present invention could be conceived.

That is, the gist of the present invention is that "a large number of linear irregularities are formed on at least one surface of a plate-shaped light guide, and light is incident from at least one end surface which is substantially orthogonal to a flow direction of most of these irregularities. A planar light-emitting body characterized by the following.

In the present invention, as light incident from the end face travels through the light guide while repeating reflection on a number of grooves, ridges, wrinkles, or other linear irregularities, these irregularities and other irregularities The angle of incidence on the surface increases, and light is emitted from the surface having irregularities or the rear surface thereof beyond the limit of total reflection. This means that as the light travels through the light guide, the ratio of the amount of emitted light to the traveling light increases, and substantially uniform light emission can be obtained over the entire surface.

In this case, by applying a reflection function to the end face facing the light receiving end, the light reaching the end face travels in the opposite direction and emits the same motion repeatedly, thereby further improving the overall uniformity of the emitted light. Can be. Also, by applying a reflection function to a portion of the light receiving end face that is not occupied by light reception, light emission efficiency can be increased from the surface.

In addition, by applying a reflection function to either the surface having the irregularities or the back surface, light can be emitted from only one of the two surfaces. Then, by gradually reducing the thickness of the plate-shaped light guide from the light receiving end toward the other end face facing the light receiving side, the attenuation of the luminance on the surface along with the progress of light can be further reduced.

 Hereinafter, embodiments will be described.

(Example) (1) On a transparent acrylic plate of 900 x 460 x 5 mm (thickness),
Approximately 900 grooves each having a width of 0.5 mm are formed on one side, and a rear plate and an end surface other than the light receiving end are subjected to aluminum vapor deposition to form a mirror plate. At the light-receiving end of the plate, 451 1-mm polymer optical fibers were used.
Light is incident by a light guide that is arranged in a row and the other end is tightly bound. In this case, the side where the optical fibers are arranged in a line is used as the light emitting end of the light guide, and is brought into close contact with the light receiving end of the plate.

Approximately 12,000 lumens of visible light is incident on the light-receiving end of the light guide using a 400-watt metal halide lamp. The average illuminance of the surface obtained at this time was about 20,000 lux.

FIG. 1 shows measurement points (intersections of lines, represented by numbers 1 to 32) on the plate. Tables 1 and 2 show the measurement results of Example (1) and the conventional example. FIGS. 2 and 3 show the attenuation of the illuminance from the light receiving end to the other end in the embodiment (1) and the conventional example.
Shown in the figure.

(2) In the embodiment (1), the light incident end 1a of the acrylic plate 1
Glue an acrylic prism 2 on the other side of the
As shown in the figure, 451 optical fibers are adhered to this prism. As a result, the light emitted from the 400 W lamp enters the two ends of the plate by the two light guides 3 and 3 ′. The average illuminance of the resulting light reached about 23,000 lux. Table 3 shows the measured values, and FIG. 6 shows the change in illuminance between both ends.

(3) In the embodiment (1), the thickness of the plate is gradually reduced so that the plate thickness at the light incident end is 10 mm and the plate thickness at the opposite end is 5 mm. The illuminance was measured. The results are shown in Table 4 and FIG.

(Effect of the Invention) The difference in illuminance in the present invention is 30% or less in Example (1) and 24% or less in Example (2). That is, variation in illuminance is small, and light attenuation due to the traveling direction of light is small. In addition, a high-luminance planar light-emitting body can be provided as a whole.

As an advantage in manufacturing, basically, a thin acrylic groove is formed in one acrylic plate, and the manufacturing process is performed in which aluminum is deposited. Therefore, manufacturing at low cost is possible.

 Therefore, the practical value of the present invention is great.

[Brief description of the drawings]

FIG. 1 is a diagram showing measurement points on a plate, and FIGS. 2 and 3 show changes in illuminance from the light receiving end to the other end. FIGS. 4 and 5 are side views showing a structure in which an acrylic prism is adhered to the edge of the plate and light is incident from both ends of the plate. FIGS. 6 and 7 are diagrams of the plates of Examples (2) and (3). It is a figure showing change of illuminance between both ends. 1 ... Acrylic plate, 2 ... Prism 3,3 '... Light guide

Continuation of front page (56) References JP-A-64-905 (JP, A) JP-A-63-318003 (JP, A) JP-A-63-293586 (JP, A) JP-A-63-181201 (JP, A) JP-A-62-165603 (JP, A) JP-A-57-54980 (JP, A) JP-A-61-32318 (JP, A) JP-A-3-54982 (JP, U) JP-A 61-182584 (JP, U) Fully open Showa 61-85801 (JP, U) Fully open Showa 61-54620 (JP, U) Fully open Showa 61-42586 (JP, U) Fully open Showa 54-25845 (JP, U) U) JP-B-58-17957 (JP, B2) JP-B-56-33681 (JP, B2) JP-B 63-18039 (JP, Y2) JP-B-58-25405 (JP, Y2) JP-B Showa 56 -47657 (JP, Y2) U.S. Pat. No. 4,277,817 (US, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02B 6/00 331 F21V 8/00 601 G02F 1/13357 G09F 9/00 332 G09F 13/18 JICST file (JOIS)

Claims (3)

(57) [Claims] 1. A plate-shaped light guide having a plurality of linear irregularities formed on at least one of a pair of main surfaces opposed to each other in parallel with each other. Light enters the light guide from at least one side end surface substantially orthogonal to the length direction of the irregularities, and the incident light is irradiated with the linear irregularities formed on the at least one principal surface and the other principal surface. Traveling in the plate-shaped light guide toward the other side end surface facing while repeating reflection at the surface, to the surface of the linear irregularities formed on the at least one main surface and the other main surface. A planar luminous body, which emits light from both or one of a main surface on which irregularities are formed and the other main surface when an incident angle exceeds a limit of total reflection due to an increase in an incident angle. 2. The planar light emitting device according to claim 1, wherein said linear unevenness is formed of a groove, a ridge or a wrinkle. 3. The surface according to claim 1, wherein a reflection function is provided on one of a pair of main surfaces of the plate-shaped light guide and on a side end surface other than the one end surface on which light is incident. Light emitter.