JP2001319514A - Planar light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a planar light source device adaptable to be small size, improving the precision of a light illuminated as a mixed-color light. SOLUTION: An angle portion of a photoconductive plate 21 rectangularly formed of a light transmissive material is cut into a planar shape to form a light receiving plane 23. An LED emitter 22 having LED elements 22G, 22R, 22B different in luminescent color is put in face contact with the light receiving plane 23 so that a light emitted by the LED emitter 22 is received through the light receiving plane 23 by the photoconductive plate 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface light source device for inputting a plurality of color lights to a light guide plate and irradiating mixed light of the color lights from the light guide plate surface.

[0002]

2. Description of the Related Art A surface light source device provided with a light guide plate for receiving light emitted from a plurality of LED light-emitting elements (light-emitting diodes) having different emission colors and irradiating the light with a surface is, for example, an LCD (liquid crystal display). Widely known as lights and the like.

FIG. 7 is a sectional view showing an example of a display device of an LCD, in which 11 is an LCD, 12 is a light guide plate as a backlight, 13 is an LED light emitter, 14 is a wiring board, and 15 is a frame. Show.

In this display device, the light emitted from the LED light emitter 13 enters the light guide plate 12, and the light guide plate 12 emits light from the surface, so that the LCD 11 is irradiated. In other words, LCD
The characters and figures displayed on the display 11 are illuminated by the light guide plate 12 and are optically projected.

FIG. 8 is a schematic front view showing a surface light source device comprising the above-described light guide plate 12 and LED luminous body 13, and FIG. 9 is a schematic side view of the same surface light source device.

As shown in the figure, the light guide plate 12 is a rectangular plate made of a translucent material (for example, a transparent synthetic resin material), and a light guide plate 12 is provided at a position opposed to the center of one short side.
An ED luminous body 13 is arranged, and the LE of the ED luminous body 13 is arranged from the center of the short side on one side.
It is an edge light type in which the light emitted from the D light emitter 13 enters.

[0007] The LED luminous body 13 includes a substrate 13a in which three LED luminous elements 13G, 13R and 13B having different luminous colors are arranged in a line, and LED luminous elements 13G, 13R and 1B.
A lens material 13b attached to the substrate 13a so as to bury the 3B is formed as an LED chip. 13G is green light (G light) and 13R is red light (R light).
) And 13B are LED light emitting elements that respectively emit blue light (B light).

When the light emitted from the LED light emitter 13 enters the light guide plate 12, each of the G light, the R light, and the B light is mixed, and the white light (W light) is triangulated in the light guide plate 12. Spread in shape.

The W light is applied to the effective illumination area 12 of the light guide plate 12.
It becomes illumination light irradiated from a. The projection angle α at which the G light, the R light, and the B light are mixed is the LED light emitting elements 13G, 13R, and 13B.
Depends on the light distribution characteristics of the light source, but in this conventional example, α = 90
°.

The upper region of the W light becomes R + G light and G light, and the lower region becomes the R + B light and B light.

[0011]

In the case of the above-mentioned light guide plate 12, the upper and lower portions of the W light are likely to be uneven in color due to the R + G light and the R + B light. Therefore, W of the effective illumination range 12a
In order to improve the accuracy of light, LED from effective illumination range 12a
It is necessary to increase the distance L0 to the light emitter 13 to set an optical path length for color mixing.

That is, the size of the light guide plate 12 is increased.
Although the distance L0 is lengthened by means such as separating the LED light emitter 13 from the light guide plate 12, there is a problem that as a result, the light guide plate 12 becomes large and the surface light source device becomes large.

Further, as shown in FIG. 10, by providing another LED illuminant 16 in addition to the LED illuminant 13, the light projection angle α at which G light, R light and B light are mixed increases. . As a result, the distance (optical path length) L0 from the effective illumination range 12a to the LED light emitters 13 and 16 becomes shorter, and the light guide plate 12 can be made smaller.

However, as described above, the LED illuminant 1
If the LED light emitters 16 are simply arranged side by side with the LED light emitting device 3, the effect cannot be expected sufficiently compared with the ratio of the production cost to be increased for the LED light emitters 16 and the circuit configuration equipment.

An object of the present invention is to provide a surface light source device suitable for miniaturization and capable of improving the accuracy of mixed color light as much as possible in view of the above-mentioned circumstances.

[0016]

Means for Solving the Problems In order to achieve the above object, according to the present invention, as a first invention, a plurality of colors of light are made to enter a quadrangular light guide plate formed of a translucent material. In a surface light source device configured to irradiate mixed light of each color light from a light guide plate surface, a light incident surface is formed at a corner of a quadrilateral light guide plate, and a plurality of color light beams are incident from the light incident surface. A surface light source device characterized by comprising a light source unit arranged is proposed.

As described above, by inputting a plurality of colors of light from the corners of the quadrilateral light guide plate, the mixed color light is spread toward the entire area of the light guide plate, and the effective illumination for the plate area of the light guide plate is achieved. The proportion of the range can be increased.
As a result, it is possible to reduce the size of the surface light source device by reducing the size of the light guide plate.

According to a second aspect of the present invention, in the surface light source device of the first aspect, light-entering surfaces are formed at a plurality of corners of the quadrilateral light guide plate, and a plurality of color lights enter from the light-entering surface. A surface light source device is proposed in which a light source unit is disposed on each of the light incident surfaces.

As described above, by allowing a plurality of colors of light to enter from a plurality of corners of the quadrilateral light guide plate, the light guide plate can be reduced in size in the same manner as in the first invention, and the precision of mixed color light can be reduced. Can be improved.

According to a third aspect of the present invention, in the surface light source device according to the first or second aspect, the light source section is configured as an LED illuminator integrally including a plurality of light emitting elements having different emission colors. A surface light source device is proposed.

According to a fourth aspect of the present invention, there is provided the surface light source device according to the second or third aspect of the present invention, wherein the LED light-emitting elements are arranged to face each other.
A surface light source device is proposed in which two adjacently arranged LED light-emitting elements are configured as an array in which light-emitting elements of different emission colors are mutually inverted.

The surface light source device configured as described above can further improve the accuracy of mixed color light in addition to the reduction in the size of the light guide plate.

[0023]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing a surface light source device according to a first embodiment, which is configured to receive light emitted from one LED light emitter 22 from an upper right corner of a rectangular light guide plate 21. FIG. 2 is a top view of the same surface light source device.

As shown in the figure, the light guide plate 21 is formed in a rectangular plate with a light-transmitting material (for example, a transparent synthetic resin material), and the light incident surface 2 is formed by cutting a right upper corner into a planar shape.
3 are provided.

The LED luminous body 22 has the same structure as the conventional LED luminous body 13, and is provided on the substrate with the LED of each emission color.
The light emitting elements 22G, 22R, and 22B are covered with a lens material. 22G is an LED light emitting element that emits green light, 22R is red light, and 22B is an LED that emits blue light.
The LED luminous body 22 is disposed so as to be in contact with the light incident surface 23 of the light guide plate 21 and each LED light emitting element is opposed to the light incident surface 23.

In the surface light source device configured as described above, the projection angle of the mixed color light is as shown by α in the figure, the light range of the R + G light and the G light is near the upper side of the light guide plate 21, and the R + B light and the B light Are generated near the right side of the light guide plate 21, respectively.

Therefore, the effective illumination range 21a becomes a rectangle similar to the light guide plate 21, and the effective illumination range 21a
Emits white light W. As a result, the size of the light guide plate 21 can be reduced.

The light ranges of the R + G light and the G light, and the light ranges of the R + B light and the B light are drawn wide in the drawings for the sake of convenience of explanation. The ratio of the effective illumination range 21a to the plate area of the light plate 21 is large.

FIG. 3 is a schematic diagram showing a surface light source device according to a second embodiment in which light is incident from two corners of a rectangular light guide plate 24 by two LED light emitters 22 and 25.

In the light guide plate 24 of the present embodiment, light-entering surfaces 23 and 26 are formed at diagonal portions of a rectangular plate formed of a translucent material.
As described above, the LED light emitter 22 is disposed on the light incident surface 23, and another LED light emitter 25 is disposed on the light incident surface 26 so as to be in contact with each other.

The LED luminous body 25 is the LED luminous body 2
2, but these LED light emitters 22 and 25 invert the color light of the LED light emitting elements arranged on the left and right sides of the LED light emitting elements 22R and 25R and enter the light guide plate 24. It is configured to emit light so as to improve the accuracy of mixed color light emitted from the effective illumination range 24a.

FIG. 4 is a schematic view of a surface light source device showing a third embodiment. In the present embodiment, the light emitted from the LED light emitters 22 and 25 enters from the upper right corner and the upper left corner of the rectangular light guide plate 27.

In this embodiment, a light incident surface 23 is formed at the upper right corner of the rectangular light guide plate 27 made of a light transmitting material, and a light incident surface 28 is formed at the upper left corner. LED light emitters 22 and 25 are provided so as to be in contact with each other.

The LED luminous bodies 22 and 25 are LED
By changing the emission colors of the LED light emitting elements located on the left and right of each of the light emitting elements 22R and 25R, the effective illumination range 27
This is a configuration for improving the accuracy of mixed light (white light W) emitted from a.

FIG. 5 is a schematic view of a surface light source device shown as a fourth embodiment, and FIG. 6 is a sectional view taken along line AA in FIG. In this embodiment, an upper right corner of a rectangular light guide plate 29 made of a translucent material is tapered, and a light incident surface 30 formed by mirror-finishing this taper is provided.

The LED light emitter 22 is arranged near the back surface of the light guide plate 29 and emits light toward the light incident surface 30. The surface light source device thus configured is
Each color light projected from the LED light emitter 22 is reflected by the light incident surface 30 and guided to the light guide plate 29.

As a result, the effective illumination range 29a is similar to the light guide plate 29 as in the above embodiments, and the effective illumination range 29a can be further increased because the optical path length in the light guide plate becomes longer. .

While the preferred embodiment of the present invention has been described above, in practicing the present invention, a square light guide plate may be used instead of a rectangular light guide plate.

Further, the light incident surface is formed not only at one corner or two corners but also at a plurality of arbitrarily determined corners.
It is possible to adopt a configuration in which light of a plurality of colors enters from these light entrance surfaces.

Further, similarly, in the reflection type surface light source device shown in FIG. 5, a plurality of corners of the quadrangular light guide plate are formed with mirror-finished light-entering surfaces, so that a plurality of colors from the plurality of corners are formed. The present invention can be implemented as a surface light source device that receives light.

[0041]

As described above, in the present invention, since a plurality of color lights enter from the corners of the quadrilateral light guide plate, the ratio of the illuminated illumination range to the plate area of the light guide plate is set to be large. Can be.

As a result, the size of the light guide plate can be made smaller than that of the conventional one, so that it is possible to provide a small-sized surface light source device suitable for low cost.

Further, if a configuration is adopted in which a plurality of color lights are made to enter from a plurality of corners of the quadrangular light guide plate, a surface light source device capable of improving the color mixing accuracy of light emitted from the effective illumination range can be obtained.

Further, when light is incident from a plurality of corners of the quadrangular light guide plate, the two LED light emitters are arranged by inverting light emitting elements of different light emission colors from each other.
The color mixing accuracy can be further improved.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a surface light sourceless device of a first embodiment configured to receive light from one corner of a light guide plate.

FIG. 2 is a top view of the surface light source device.

FIG. 3 is a schematic view illustrating a surface light source device according to a second embodiment, which is configured to receive light from a diagonal portion of a light guide plate.

FIG. 4 is a schematic diagram illustrating a surface light source device according to a third embodiment having a configuration in which light enters from upper left and right corners of a light guide plate.

FIG. 5 is a schematic diagram of a fourth embodiment in which light enters from a light entrance surface formed of a reflection surface formed at one corner of a light guide plate.

FIG. 6 is a sectional view taken along line AA in FIG.

FIG. 7 is a cross-sectional view of a conventional LCD display device including a surface light source device as a backlight.

FIG. 8 is a schematic view of a surface light source device provided in the above-mentioned conventional LCD display device.

FIG. 9 is a schematic side view of the above-described conventional surface light source device.

FIG. 10 is a schematic view showing a conventional surface light source device provided with two LED light emitters.

[Explanation of symbols]

 21, 24, 27, 29 Light guide plate 21a, 24a, 27a, 29a Effective illumination range 22, 25, LED light emitter 23, 26, 28, 30 Light incident surface

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) // F21Y 101: 02 G02F 1/1335 530 F term (reference) 2H038 AA55 BA06 2H091 FA23Z FA45Z LA11 LA15 5F041 AA11 AA14 AA47 DC81 EE25 FF11

Claims (4)

[Claims] 1. A quadrilateral light guide plate formed of a translucent material,
In the surface light source device having a configuration in which a plurality of color lights are incident and mixed light of each color light is emitted from a light guide plate surface, a light incident surface is formed at a corner of a quadrilateral light guide plate, and a plurality of colors are formed from the light incident surface. A surface light source device comprising a light source unit configured to receive the color light. 2. The surface light source device according to claim 1, further comprising: a light source unit having a light incident surface formed at a plurality of corners of the quadrangular light guide plate, and receiving a plurality of color lights from the light incident surface. A surface light source device which is arranged on each of the light incident surfaces. 3. The surface light source device according to claim 1, wherein the light source unit is configured as an LED illuminant in which a plurality of light emitting elements having different emission colors are integrally formed. 4. The surface light source device according to claim 2, wherein the LED light-emitting elements disposed in opposition or two LED light-emitting elements disposed adjacent to each other invert light-emitting elements of different emission colors from each other. A surface light source device comprising an array.