JP4483020B2 - Surface emitting device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a surface light emitting device used as a light source for a backlight of a liquid crystal display unit such as a mobile phone.
[0002]
[Prior art]
Conventionally, a liquid crystal display unit of a mobile phone is a combination of a liquid crystal display panel constituting a liquid crystal display screen and a backlight structure for allowing a display image to be seen even in the dark. A typical backlight structure includes, for example, a green or red light emitting diode (LED) as a light source, and light from the light emitting diode is provided on the entire back surface of the liquid crystal display panel. The light guide plate is made of a transparent resin such as acrylic, and is positioned so as to receive light from the light emitting diode from the introduction portion bent downward according to the arrangement position of the light emitting diode and cover the back surface of the liquid crystal display panel. Light is emitted from the surface emitting part. In such a light guide plate, in order to promote the emission of light to the liquid crystal display panel, a scattering reflection layer having a minute uneven pattern is generally formed on the back surface side.
[0003]
[Problems to be solved by the invention]
Traditionally, red and green single-color light emitting diodes were incorporated as light sources for backlights, but with the diversification of image display, red, green, and blue light emitting diodes have been provided. Mixed color emission that emits orange light has become the mainstream in recent years.
[0004]
However, when two light emitting diodes of red and green are provided, light of different emission colors is introduced into the light guide plate from each position. For this reason, the respective colors of red and green are not sufficiently mixed, resulting in a light emission color in which the red or green color is emphasized depending on the location of the light guide plate, and uniform orange light emission cannot be obtained. In other words, although light from the scattering reflection layer on the lower surface of the light guide plate can be diffused, red and green are taken in from different positions in the light introduction part from the light emitting diode, so the color mixing degree of both colors is low. The display screen cannot emit orange light uniformly.
[0005]
As described above, in the surface light emitting device using the conventional light guide plate that introduces light from the light emitting diode and emits light toward the back surface of the liquid crystal display panel, when a plurality of light emitting diodes of different colors are used as a light source, color mixing is not possible. There is a problem that it is not enough.
[0006]
SUMMARY OF THE INVENTION An object of the present invention is to provide a surface light emitting device that can emit light from a light guide plate that is uniform and has no color unevenness by uniformly diffusing light from a plurality of light emitting diodes of different colors from an introduction portion. .
[0007]
[Means for Solving the Problems]
The present invention provides a surface light-emitting device including a plurality of light-emitting elements having different emission colors and a light-guiding plate that introduces light from the light-emitting elements and emits the light from a planar light-emitting portion. A light guide part formed outward from an edge of the light emitting part, and an introduction part that is included as a part of the light guide part and faces a light emission observation surface side of the plurality of light emitting elements. Is characterized in that a diffusion part for diffusing light from the plurality of light emitting elements to the entire light guide part is formed.
[0008]
According to the present invention, it is possible to obtain a surface light emitting device that can emit light from a light guide plate that is uniform and has no color unevenness.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
A first invention of the present application is a surface light emitting device comprising a plurality of light emitting elements having different emission colors and a light guide plate that introduces light from the light emitting elements and emits the light from a planar light emitting portion. Is included as a part of the light guide part, a light emitting part having a square planar shape, a light guide part formed in a substantially triangular shape from one edge to the outside along one side of the light output part, and And an introduction part facing the light emission observation surface side of the plurality of light emitting elements at a position corresponding to a corner part of the light emitting part, and the light guide part receives light from the plurality of light emitting elements in the introduction part The light emitting device is characterized in that a diffusing portion comprising a wave-shaped surface to be diffused is formed, and light from the light emitting element introduced from the introducing portion is spread to the entire light guiding portion by the diffusing portion. Because it is diffused, the emission color from multiple light-emitting elements with different emission colors is uniform. An effect that can be emitted from the light emitting unit by mixing of.
[0010]
According to a second aspect of the present invention, in the surface light-emitting device according to claim 1, the diffusing portion is a minute unevenness on an inclined surface inclined approximately 30 ° to 60 ° with respect to the optical axis of the light emitting element. It is an apparatus and has the effect | action that the light from a light emitting element can be diffused to a light guide part by the diffusion part of the minute unevenness | corrugation on an inclined surface.
[0011]
A third invention of the present application includes a case that surrounds the outer periphery of the light guide plate and covers the diffusion portion, and an inner surface of the case facing the light diffusion portion is a light reflection surface to the light guide portion. The surface light-emitting device according to claim 2, wherein the light-emitting portion can be increased by using the reflection surface of the case to improve the light emission luminance.
[0012]
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0013]
1 is a longitudinal cross-sectional view of the main part of the surface light emitting device according to the present embodiment, FIG. 2 is a cross-sectional view of the main part showing the arrangement of the light guide plate in the case, and FIG. FIG. 4 is a schematic perspective view of the light guide plate. FIG.
[0014]
As shown in FIG. 1, the surface light emitting device according to the embodiment of the present invention includes a case 1, two light emitting diodes 2a and 2b incorporated in the case 1, and these light emitting diodes 2a and 2b. And a light guide plate 3 that emits light upward in the figure. A liquid crystal display panel 11 filled with liquid crystal is disposed above the light guide plate 3, and light emitted from the light guide plate 3 serves as a backlight of the liquid crystal display panel 11.
[0015]
The case 1 is formed of white synthetic resin, and as shown in FIG. 3, a reflective surface 1a having an angle of about 45 ° is provided at a position corresponding to the position immediately above the position where the light emitting diodes 2a and 2b are arranged. Yes. The light emitting diode 2a emits green light and the light emitting diode 2b emits red light.
[0016]
The light guide plate 3 is formed of a transparent acrylic resin, and as shown in FIG. 2, a light emitting portion 3a having a substantially square planar shape and a light guide portion 3b formed in a substantially triangular shape along one side thereof. It is provided. On the bottom surface side of the light emitting portion 3a, a scattering reflection layer 3a-1 is formed as an uneven surface having a satin-like or minute cylindrical protrusion. The light guide portion 3b is formed by forming an introduction portion 3c having a shape bent downward as shown in FIG. 3 at a position corresponding to the corner portion of the light emitting portion 3a. The introduction portion 3c has a shape covering the light emitting diodes 2a and 2b, and a surface corresponding to the reflection surface 1a of the case 1 is an inclined surface 3d. A diffusion portion 3e is formed on the surface of the inclined surface 3d. Yes. The diffusion unit 3e is a minute wave-shaped surface having a pitch of about 60 μm and a peak height of about 25 μm, and diffuses light from the light-emitting diodes 2a and 2b into the entire light guide unit 3b.
[0017]
In the above configuration, the light from the light emitting diodes 2a and 2b is incident from the lower surface of the introduction portion 3c, and the light is diffusely reflected by the minute wave-like uneven diffusion portion 3e so as to spread over the entire light guide portion 3b. Further, the light that has passed through the diffusing unit 3e travels toward the reflecting surface 1a of the white case 1, and is collected from the reflecting surface 1a through the diffusing unit 3e to the light guide unit 3b. Thus, the light from the introduction part 3c is diffused by the diffusion part 3e including the reflected light from the reflection surface 1a, and spreads over the entire light guide part 3b. Therefore, the green light emission from the light emitting diode 2a and the red light emission from the light emitting diode 2b are mixed in the light guide part 3b before reaching the light emitting part 3a.
[0018]
That is, for example, in the case where the light emitting diodes 2a and 2b are arranged at the edge of the light emitting portion 3a and are directly incident, only the regions close to the light emitting diodes 2a and 2b emit light with high brightness, and green and red are The light emission color is uneven and uneven. On the other hand, green and red light emission colors are sufficiently mixed in the light guide portion 3b by the diffusion portion 3e, and the mixed color is introduced into the light emitting portion 3a. Therefore, since the light that has been mixed with green and red in the light guide portion 3b and becomes orange enters the light emitting portion 3a and emits light, the green and red are not unevenly distributed with respect to the liquid crystal display panel 11. Light can be irradiated.
[0019]
Since the lower surface of the light emitting portion 3a is the scattering reflection layer 3a-1, the light emission mixed in orange from the light guide portion 3b is efficiently reflected to the liquid crystal display panel 11 side. Therefore, the orange light can be reliably applied to the liquid crystal display panel 11, and an orange light-emitting liquid crystal display screen with no color unevenness can be obtained.
[0020]
【The invention's effect】
In the present invention, light from a plurality of light emitting elements having different emission colors is introduced from the introduction part to the entire light guide part through the diffusion part and then introduced into the light emitting part. This can be eliminated when the light is guided to the light guide part, and uniform light emission of mixed colors can be obtained from the light emitting part.
[Brief description of the drawings]
FIG. 1 is a schematic longitudinal sectional view showing a main part of a surface light emitting device according to the present invention. FIG. 2 is a cross-sectional view of the main part showing an arrangement of a light guide plate in a case. Longitudinal sectional view of the main part for showing the positional relationship of the diode [FIG. 4] Schematic perspective view of the light guide plate [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Case 1a Reflection surface 2a, 2b Light emitting diode 3 Light guide plate 3a Light-emitting part 3a-1 Scattering reflection layer 3b Light guide part 3c Introduction part 3d Inclined surface 3e Diffusion part 11 Liquid crystal display panel

Claims (3)

In a surface light emitting device including a plurality of light emitting elements having different emission colors and a light guide plate that introduces light from the light emitting elements and emits the light from a planar light emitting portion, the light guide plate has a square planar shape. The light emitting part, a light guide part formed in a substantially triangular shape from one edge to the outside along one side of the light emitting part, and a corner of the light emitting part included as a part of the light guiding part and a introduction portion facing the light emission observing surface side of the plurality of light emitting elements at a position corresponding to the part, the said inlet portion shaped waveform for diffusing light from the plurality of light emitting elements throughout the light guide portion A surface light-emitting device, characterized in that a diffusion portion comprising the surface of the surface is formed.   The surface light-emitting device according to claim 1, wherein the diffusing portion is a minute unevenness on an inclined surface inclined approximately 30 ° to 60 ° with respect to the optical axis of the light-emitting element.   The light guide plate includes a case that surrounds an outer periphery of the light guide plate and covers the diffusion portion, and an inner surface of the case facing the light diffusion portion is a light reflection surface for the light guide portion. 2. The surface light-emitting device according to 2.

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