JPH06242321A - Surface emitting body for backlight - Google Patents

Abstract

PURPOSE:To provide a display face backlight device capable of uniformly holding the luminance of a display face independently of the nearby distance of a display plate such as a liquid crystal panel. CONSTITUTION:In a device fixing a light source 3 to a light source holder 1 and fixing the end part of a plate-like light guiding plate 6 having transmissivity along the holder 1, ruggedness 9 for uniformly and dispersion- transmitting light from the inside of the plate 6 to the front side, or a light aligning plate 16 is formed along the surface side of the plate 6 and ruggedness 9 for uniformly and dispersion-transmitting light from the inside of the plate 6 to the surface side of the plate 16, and a tunnel part 8 covered with a reflecting face 7 for reflecting light applied from the light source 3 in the top direction of the plate 6 is formed on the base end part side of the plate 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface light emitter for a backlight for irradiating light on a liquid crystal display surface or a back surface of a photographic film or a see-through plate in the drawings.

[0002]

2. Description of the Related Art Conventionally, as a backlight device for a liquid crystal display surface or a display surface such as a see-through plate, a light guide plate made of an acrylic plate having a straight cross section is attached to a light source holder equipped with a light source such as a fluorescent tube. It was known that a diffusing plate was combined on the surface side of the with a certain interval.

[0003]

However, in the above-described conventional example, the light guide plate gradually decreases in brightness from the base end side closer to the light source toward the tip end side and uneven brightness occurs. Did not reach the tip side. Therefore, in order to keep the brightness of the display surface uniform, the liquid crystal plate must be separated from the light guide plate of the backlight device, and when the irradiation area is large, light sources must be mounted on both ends of the light guide plate. Without increasing the thickness of the backlight device,
There is a drawback in that the cost of the light source is unnecessarily increased to maintain the brightness of the light source.

[0004]

In order to solve the above-mentioned problems, the present invention has a light source 3 attached to a light source holder 1, and a plate-like light guide plate 6 having translucency along the light source holder 1. In the device having the fixed end portion, the first feature is that the reflecting surface 10 is formed on the back side of the light guide plate 6 and the tip side of the back side is a curved surface that converges toward the tip. The second feature is that the surface of the light guide plate 6 is provided with the unevenness 9 for uniformly dispersing and transmitting the light inside the light guide plate 6 to the front side. A light-regulating plate 16 is provided along the front surface side of the light guide plate 6, and a concavo-convex portion 9 is formed on the rear surface side of the light guide plate 16 to uniformly disperse and transmit the light in the light guide plate 6 to the front surface side of the light control plate 16. Is the third feature. A fourth characteristic is that the base end side of the light guide plate 6 is formed as a tunnel portion 8 covered with a reflection surface 7 that reflects the light from the light source 3 toward the tip end of the light guide plate 6.

[0005]

When the light emitted from the light source 3 passes through the inside of the tunnel portion 8 covered with the reflection surface 7, the light is reflected far toward the tip side of the light guide plate 6. The light that has passed through the tunnel portion 8 and irradiated into the light guide plate 6 is repeatedly refracted and reflected by the unevenness 9 on the surface side of the light guide plate 6 and the reflection surface 10 on the back surface of the light guide plate 6, and at the same time, on the back surface of the light guide plate 6. Due to the curved surface on the tip side, the weak light reaching the tip side of the light guide plate 6 is concentrated and converged on the surface side, and finally the uneven lines 9 make uniform brightness on the front side in a direction perpendicular to the surface of the light guide plate 6. To penetrate. As a result, even when the display plate 12 such as a liquid crystal panel is installed on the front surface side of the light guide plate 6, the brightness of the display surface is kept uniform regardless of the proximity distance of the display plate 12.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Explaining in detail the embodiments shown below, a light source holder 1 (having a total length of 150 mm) having a U-shaped cross section formed of white polycarbonate or the like has a longitudinal direction extending from one end to the other end of its inner side surface. A groove 2 is provided in the groove 2, and a rod-shaped light source 3 made of a cold cathode fluorescent tube or the like is provided in the groove 2.
Is accommodated, and a reflective surface 4 is formed on the inner surface of the groove 2 around the light source 3 by applying a reflective paint or the like so that all the light is irradiated to the open surface side of the groove 2.

The light source holder 1 has a rectangular shape (150
(mm x 100 mm) light guide plate 6 made of a transparent acrylic plate
(Thickness 3 mm) is fitted and fixed in the groove portion 2, and the light guide plate 6 has a constant projection surface on the base end side (the side where the light source holder 1 is attached), a back surface and both side surfaces. A tunnel portion 8 is formed which is covered with a reflective surface 7 having a width (15 mm) and which does not leak light to the outside.

On the surface side of the light guide plate 6, from the edge portion of the light projecting / reflecting surface 7 to the tip end of the light guide plate 6, the depth of 0.
An uneven strip 9 having a sawtooth cross section is formed in parallel with the longitudinal direction so as to form an isosceles triangle having a pitch of 1 mm, a pitch of 0.4 mm, and peaks and valleys of 90 °. Further, the light guide plate 6 has a curved surface R formed on the front end side of the rear surface thereof, and a reflective surface 10 is formed on the rear surface of the rear surface by means such as application of a reflective paint or application of a reflective sheet. A diffuser plate 12 made of a liquid crystal plate or the like is attached in parallel with the light guide plate 6 above the light guide plate 6 of the backlight device body 11.

According to the above structure, the light emitted from the light source 3 of the fluorescent tube party passes through the inside of the tunnel portion 8 covered with the light projecting / reflecting surface 7 and is directed toward the front end of the light guide plate 6. The light is reflected and projected, and is sent farther as compared with the case where the light is directly guided into the light guide plate 6. The light that has passed through the tunnel portion 8 and irradiated into the light guide plate 6 is repeatedly refracted and reflected by the uneven strips 9 on the surface of the light guide plate 6 and the reflection on the reflecting surface 10 on the back surface of the light guide plate 6, and at the front end of the back surface of the light guide plate 6. The curved surface on the side concentrates on the tip side of the light guide plate 6. Therefore, even if the inside of the light guide plate 6 is far away from the light source 3, uniform brightness is maintained from the base end side to the tip end side, and the uneven strips 9 on the surface of the light guide plate 6 are separated from the reflection surface 10. It has the property of transmitting reflected light at a right angle to the diffuser plate 12 side and uniformly over the entire surface. As a result, the display surface of the diffusion plate 12 is uniformly illuminated from the back side, and a uniform light emitting display surface with no brightness unevenness is obtained.

In this case, instead of forming the uneven line 9 on the surface of the light guide plate 6, a rectangle (150 m) having the same shape as the light guide plate 6 in plan view is used.
(m × 100 mm), a light control plate 16 made of a transparent resin plate or a lens film is superposed on the surface of the light guide plate 6, and a concave-convex strip 9a having a sawtooth cross-section similar to the above is formed on the back surface of the light control plate 16. May be.

Further, instead of making the front surface and the back surface of the light projecting / reflecting surface 7 to be smooth surfaces, as shown in FIGS. It is also possible to project the light to a farther distance by adjusting. In this case, the dimensions of the uneven slopes employed in this embodiment will be described. As shown in FIG. 3, depth a; 0.5 mm, first slope b; 2 mm, second slope c;
2 mm, third slope d; 1 mm, fourth slope e; 2 mm, fifth slope f; 1 mm, sixth slope g; 4 mm.

Further, the entire back surface of the back surface of the light guide plate 6 is covered by the reflecting surface 1.
Instead of setting it to 0, the reflection points 18 arrayed in the front, rear, left, and right as shown in FIGS. 5 and 6 may be applied to the entire back side by means such as printing or coating. In this case, the size of the reflection point 18 is proportional to the distance from the light source 3, the reflection point 18 closest to the light source 3 is minimized, and the reflection point 18 is gradually increased as the distance from the light source 3 increases. The sex can be further maintained. In this case, since the front end side of the back surface of the light guide plate 6 is formed into a curved surface, it is possible to reduce the change in the diameter or the density of the reflection points at the perspective position, thereby facilitating the working process.

[0013]

According to the device of the present invention configured as described above, the light reaches the light guide plate even at a position distant from the light source as compared with the conventional device, so that a wide light emitting surface can be obtained. It is possible to prevent uneven brightness on the light emitting surface and obtain uniform brightness. Therefore, when applied to a liquid crystal display surface, the liquid crystal plate can be attached in close contact with the light control plate, and the backlight portion or the entire device using the backlight can be thinned.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an embodiment of the present invention.

FIG. 2 is a side sectional view showing another embodiment of the present invention.

FIG. 3 is a partially enlarged view showing an uneven strip tunnel portion.

FIG. 4 is a partially enlarged view showing a saw-toothed concavo-convex surface on the back side of the light control plate.

FIG. 5 is a plan view showing an embodiment of the present invention.

[Explanation of symbols]

 1 Light source holder 2 Groove part 3 Light source 6 Light guide plate 7 Reflective surface 8 Reflective surface 9 Uneven line

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Makoto Gonda 5-17-9 Minamioi, Shinagawa-ku, Tokyo Kuroda Electric Co., Ltd. Tokyo branch office (72) Inventor Shigetoshi Sekiyama 2-32-27 Okubo, Konan-ku, Yokohama

Claims (4)

[Claims] 1. A device in which a light source (3) is attached to a light source holder (1), and an end of a light-transmitting plate-like light guide plate (6) is fixed along the light source holder (1). A surface light emitter for a backlight, wherein a reflecting surface (10) is formed on the back side of a light plate (6) and the front side of the back side is a curved surface that converges toward the tip. 2. The surface light emitter for a backlight according to claim 1, wherein the surface of the light guide plate (6) is provided with irregularities (9) that allow the light in the light guide plate (6) to be uniformly dispersed and transmitted to the front side. . 3. A light-regulating plate (16) is provided along the front surface side of the light guide plate (6), and the light inside the light guide plate (6) is provided on the rear surface side of the light control plate (16) on the surface of the light control plate (16). The surface light-emitting body for a backlight according to claim 1, wherein irregularities (9) for uniformly dispersing and transmitting the light are formed on the side. 4. A light source (3) is provided on the base end side of the light guide plate (6).
The surface light emitter for a backlight according to claim 1, wherein the surface light emitter for a backlight is formed as a tunnel portion (8) covered with a reflection surface (7) for reflecting light from the light guide plate (6) toward a tip direction.