JP3142808B2 - Surface emitting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LED which is most suitable as a light source for illuminating a liquid crystal panel of various portable devices such as a portable telephone, a PDA (Personal Digital Assistants) and a handheld GPS (Global Positioning System).
(Light Emitting Diode) The present invention relates to a surface light emitting device using a light source.

[0002]

2. Description of the Related Art For example, portable devices such as a portable telephone, a PDA, and a handheld GPS are equipped with a surface light emitting device for illuminating a liquid crystal panel surface as a display unit.

FIG. 11 shows a schematic structure of a surface light emitting device used in this kind of portable equipment. This surface light emitting device is schematically configured including a rod-shaped LED light source 51, a light guide member 52, and a reflection member 53. The LED light source 51 includes a rectangular reflecting case 54. The reflection case 54 includes a plurality of LEDs (two in the illustrated example) 55 wired and connected so as to emit a predetermined color in a concave window formed on one surface.
Are juxtaposed. The light guide member 52 is formed in a square plate shape,
It is housed in a bottomed box-shaped reflecting member 53 having an open upper surface. In the reflecting member 53, the light emitting surface faces the light guiding member 5.
The LED light source 51 is also housed together with the LED light source 51 in close contact with the right side surface.

In the surface light emitting device having the above-described structure, light emitted from the LED of the LED light source 51 is incident on the right side of the light guide member 52, and the incident light is reflected in the reflection member 53 to be reflected by the light guide member 52. Of the light guide member 52
Emits surface light in a predetermined color toward the outside.

[0005]

The light distribution characteristics (directivity) of the LED 55 used as the light source of the above-mentioned surface light emitting device vary depending on the lens shape and material. It shows a light distribution characteristic in which the luminous intensity in the direction is the highest and the luminous intensity decreases in the horizontal direction.

In the above-mentioned conventional surface light emitting device, LE
Since the D light source 51 is arranged on the side surface of the light guide member 52, light cannot be emitted within a range of 180 °. That is, although sufficient light can enter the optical axis direction of the LED 55, sufficient light cannot enter the side surface direction of the light guide member 52 orthogonal to the optical axis. For this reason, as shown by the black dots in FIG.
A dark area was formed on both sides of the LED 55 on the light emitting device 2, and the light guide member 52 could not be uniformly surface-emitted over the entire surface. As a result, when this type of conventional surface light emitting device is used as a light source for illuminating a liquid crystal panel of various portable devices, there is a problem that a part of the display of the liquid crystal panel becomes dark and lacks visibility.

In view of the above, the present invention has been made in view of the above-mentioned problems. The present invention has been made to improve the efficiency of incidence on a light-guiding member so that uniform surface light emission can be performed without the occurrence of dark places. It is an object of the present invention to obtain a surface emitting device that is optimal as a light source for illuminating a liquid crystal panel.

[0008]

Next, means for solving the above problems will be described with reference to the drawings corresponding to the embodiments. The invention according to claim 1 is a square plate in which a light introduction surface 25 cut out at a predetermined curvature is formed at least at one corner, and light introduced from the light introduction surface 25 is emitted from a front surface or a rear surface forming a light emission surface 26. The light guide member 22, the LED 2 for emitting light of a predetermined color, and the concave window 9 facing the light introduction surface 25 are formed with openings, and the concave portions 9 are formed so as to fit within the region of the light introduction surface 25. The LED 2 is accommodated in the window 9, and positioning surfaces 11 a, 11 a are formed on both sides of the concave window 9 at an angle substantially equal to the angle between the surfaces adjacent to the light introduction surface 25. The projections 12 and 13 having substantially the same curvature as the light introduction surface 25 are provided on the positioning surfaces 11a and
The LED light source 1 includes a reflective case 8 formed between upper and lower peripheral portions of the concave window portion 9 between the upper and lower outer portions of the concave window portion 11a. A light-emitting surface 14 faces the light-introducing surface 25, the protrusions 12, 13 abut on upper and lower positions of the light-introducing surface 25, and the positioning surfaces 11 a, 11 a are adjacent to the light-introducing surface 25. The light guide member 22 has a hemispherical microprojection 27 having a mirror surface or a hemispherical microprojection having a roughened surface. 27 is formed with a density inversely proportional to the distance from the LED light source 1, and includes a frame-shaped reflecting member 34 with open upper and lower surfaces for reflecting incident light in a predetermined direction,
The light guide member 22 is housed and fixed in the reflection member 34 together with the LED light source 1 with the microprojections 27 facing upward.

With such a configuration, when the above-mentioned surface light emitting device is used as a liquid crystal panel front light, the light guide member 2 is moved with respect to the frame-shaped reflection member 34 having open upper and lower surfaces.
2 is an LED light source 1 with the micro projections 27 facing the upper side.
The liquid crystal panel 35 is disposed in close contact with the front surface of the liquid crystal panel 35. Then, when the LED 2 is driven and emits light, the light is incident from the light emitting surface 14a to the concave surface 25 serving as the light introduction surface of the light guide member 22. When light is incident on the concave surface 25, the light is reflected toward the light emitting surface 26 by the inner wall surface of the reflecting member 34 and the minute projections 27 formed on the light guide member 22. Thus, the light exit surface 26 of the light guide member 22 emits surface light uniformly over the entire surface, and irradiates the surface of the liquid crystal panel 35 with uniform light.

[0010]

1 is a perspective view of an LED light source used in a surface light source device according to the present invention, FIG. 2 is a plan view of the LED light source, and FIG. 3 is an equivalent circuit diagram of the LED light source.

As shown in FIG. 1 and FIG.
Has, as light emitting elements, two LEDs 2 composed of rectangular micro chips and having different emission colors. Specifically, L
The ED 2 is a blue light emitting diode (hereinafter, referred to as a blue LED) 2A made of, for example, an InGaN material, for example, In.
Yellow light emitting diode made of GaAlP material
(Referred to as yellow LED) 2B. L of these two colors
The EDs 2A and 2B are mounted on a frame-shaped lead frame 3 made of a thin metal plate having a thickness of, for example, about 0.2 mm.

The lead frame 3 is formed of a conductive member obtained by plating a surface of a thin metal plate made of an alloy such as phosphor bronze. As the plating process, after applying the base of Cu plating to the metal thin plate, the reflection efficiency is good and the LED
Ag plating, which is familiar with bonding of 2, is applied.

The lead frame 3 includes LEDs 2A, 2B
Element mounting pattern 4 on which each LED 2A, 2
And an external terminal 5 to which a drive signal for driving B to emit light is supplied.

The external terminal 5 has one anode terminal 5a and two cathode terminals 5b, 5b, which are led out in parallel at equal intervals.
C. In the illustrated example, the cathode terminal 5c of the LED 2B extends downward from the element mounting pattern 4 on which the LEDs 2A and 2B are mounted. On both sides of the element mounting pattern 4, connection patterns 6 (6a, 6b) are formed. From one connection pattern 6a, each L
An anode terminal 1a common to the ED light sources 2A and 2B is led out downward. Also, the other connection pattern 6b
, The cathode terminal 1b of the LED 2A is led out downward.

The LEDs 2A and 2B are mounted on a common element mounting pattern 4 and are fixed by, for example, die bonding of Ag paste, and are connected to the external terminals 5 by, for example, wire bonding of a wire 7 made of gold. ing.

In the illustrated example, the blue LED 2A has a negative electrode and a positive electrode formed on the upper surface. In addition, yellow LE
D2B has a positive electrode formed on the upper surface and a negative electrode formed on the lower surface.

In this embodiment, the lower surface of the blue LED 2A and the lower surface (-electrode) of the yellow LED 2B are fixed on the element mounting pattern 4 by die bonding. Blue LED
The + electrode of 2A and the upper surface (+ electrode) of the yellow LED 2B are
Each of them is connected to one of the connection patterns 6a by wire bonding. The negative electrode of the blue LED 2A is
The other connection pattern 6b is connected by wire bonding. Thereby, each LED 2A, 2B
In a state where the wiring with the external terminal 5 is connected, the external terminal 5
Are mounted on the element mounting pattern 4 side by side in the lead-out direction.

As shown in FIG. 3, each LED 2A, 2B
The anode terminal 5a is connected as a common terminal to the + side of the power supply circuit 15, and the cathode terminals 5b and 5c are connected to the − side of the power supply circuit 15 via current limiting resistors R1 and R2, respectively. The resistance values of the current limiting resistors R1 and R2 are set to optimal values in advance so that white light is emitted from the LED light source 1.

Specifically, as shown in the chromaticity diagram of FIG.
Dominant wavelength λdA = 470n as blue LED 2A
m and dominant wavelength λd as yellow LED 2B
Use B = 576 nm. And each current limiting resistor R
When the LEDs 2A and 2B are driven to emit light simultaneously while changing the values of R1 and R2, the wavelength of the emitted color moves on a straight line connecting the wavelengths λdA and λdB on the chromaticity diagram of FIG. Therefore, the current limiting resistors R1 and R2 are variably adjusted to set respective resistance values so that desired white light is obtained.

As described above, white light can be obtained by simultaneously driving the LEDs 2A and 2B to emit light at a constant current ratio via the current limiting resistors R1 and R2.

A thin reflective case 8 formed by insert molding is formed on the lead frame 3 to which the LEDs 2A and 2B are connected by wiring so as to cover the element mounting pattern 4 except for the mounting portions of the LEDs 2A and 2B from above and below. I have. The reflection case 8 is formed of a resin having excellent heat resistance and high reflection efficiency. As a specific material, for example, a PBT resin containing a reflective material containing 15% glass is used.
Further, the height T of the reflection case 8 is determined by the light guide member 22 described later.
The dimensions are set to be approximately the same as the thickness of

As shown in FIG. 1 and FIG.
In the center of the surface, a rectangular concave window 9 opening toward the element mounting pattern 4 is formed so that the LEDs 2A and 2B are exposed. The concave window 9 is formed so as to fit within a region of a concave surface (light introduction surface) 25 of the light guide plate 23 described later.

The left and right inner peripheral wall surfaces of the concave window portion 9 form a tapered surface 10 inclined at a predetermined angle so as to spread from the element mounting pattern 4 side toward the surface of the reflection case 8. The tapered surface 10 guides the light emitted from each of the LEDs 2A and 2B and spreads to the front side of the concave window portion 9.

In FIG. 2, positioning projections 11, 1 having positioning surfaces 11a, 11a forming a predetermined angle are provided on both left and right sides of the outer peripheral portion of the concave window portion 9 in the reflection case 8 main body.
1 is integrally formed. This positioning surface 11
The angle between a and 11a is set substantially equal to the angle between the side surfaces adjacent to the concave surface 25 of the light guide plate 23 described later. The illustrated example is an example in which a light guide plate made of a rectangular plate material is used, and is set to 90 °.

In FIG. 2, an arc-shaped upper protruding portion 12 and a lower protruding portion 13 are provided between the left and right positioning protrusions 11 above and below the outer peripheral edge portion of the concave window portion 9 on the reflection case 8 main body. It is formed integrally. The upper protruding portions 12 and the lower protruding portions 13 are formed in circular arc shapes with the tip edges 12a and 13a having substantially the same curvature as the concave surface 25 of the light guide plate 23 so as to be in close contact with a concave surface 25 of the light guide plate 23 described later. Have been.

As shown in FIG. 1, a sealing member 14 made of a transparent resin such as epoxy resin or silicon having a light transmitting property is filled in the concave window portion 9. This sealing member 14
Protects each LED 2A, 2B, and
From the front side of the concave window portion 9. In addition, the surface of the sealing member 14 has the LEDs 2A, 2B
A light emitting surface 14a for emitting light from the outside toward the outside is formed.

Next, FIG. 5A is a diagram showing an example of a surface light emitting device on which the LED light source 1 is mounted, FIG. 5B is a side view thereof, and FIG. 6 is a line II in FIG. FIG. 7 is a partially enlarged plan sectional view of the same surface light emitting device.

The surface light emitting device 21 is employed as a backlight of a liquid crystal panel, and is generally constituted by including the LED light source 1, a light guiding member 22, and a reflecting member 24.

As shown in FIG. 5A, the light guide member 22
Is formed in a rectangular square plate shape by a transparent member such as methacrylic resin. At the corner of the light guide member 22 where the LED light source 1 is arranged, a concave surface 25 that is a notch with a predetermined curvature and forms a light introduction surface is formed.

The light guide member 22 has one surface (the front surface or the back surface) forming a light emission surface 26 for emitting light introduced from the LED light source 1 via the concave surface 25 to the outside. On the other surface of the light guide member 22 facing the light emission surface 26, that is, on the opposite surface of the light emission surface 26, a hemispherical microprojection 27 whose surface is a mirror surface is integrally formed in a predetermined pattern shape. I have. The fine projections 27 are set to an optimum density depending on the position from the LED light source 1. In other words,
According to the light distribution characteristics (directivity) of the LED light source 1, the light emitted from the light exit surface 26 of the light guide member 22 is set to be uniform over the entire surface.

More specifically, the density of the minute projections 27 near the LED light source 1 is reduced, and the density of the minute projections 27 is increased as the distance from the LED light source 1 increases. Also, LE
The density of the fine protrusions 27 in the portion where the luminous intensity of the D light source 1 is high is reduced, and the density of the fine protrusions 27 in the portion where the luminous intensity is low is increased.
That is, the minute projections 27 are formed at a density inversely proportional to the distance from the LED light source 1. The formation pattern of the minute projections 27 may be a random pattern instead of a regular pattern. Further, the outer diameter of the minute projection 27 may be changed.

Here, the light guide member 22 having the fine projections 27 is manufactured according to the following procedure. (1) A photoresist is uniformly applied on the surface of a glass substrate, and a laser beam is applied to a predetermined gradation pattern, that is, a position on the photoresist corresponding to a desired distribution of the minute projections 27. (2) When the photoresist surface is developed after the irradiation of the laser beam, the portion hit by the laser beam disappears, and a hemispherical recess having a diameter of 50 to 100 and a height of 10 to 15 μm is formed on the surface of the glass substrate. Is done. (3) Silver plating is applied to the entire surface of the glass substrate having the hemispherical depressions formed thereon, and nickel is electroformed thereon to obtain a thickness of 2
Make a 50-300 μm metal master. (4) A metal master is attached to an injection mold by a vacuuming method, and the light guide member 22 is manufactured by an injection molding method using a material such as methacrylic resin. As a result, the light guide member 22 on which the fine protrusions 27 are formed in a desired distribution is completed.

In the above description, the minute projections 27 have been described as being integrally formed with the light guide member 22.
When the configuration of the surface light emitting device 21 shown in FIG. 5 is adopted, the surface of the fine projection 27 may be roughened to roughen the surface to scatter the incident light. May be formed.

The reflection member 24 is formed in a box shape with a bottom and only the upper surface is open. At the corner where the concave surface 25 of the light guide member 22 is located, and at the lower right corner in FIG. 2, there is formed a mounting recess 28 that matches the outer shape of the reflection case 8 of the LED light source 1. In addition, a terminal insertion hole 28a through which the external terminal 5 of the LED light source 1 is inserted is formed in the mounting recess 28 so as to communicate therewith.

The light guide member 22 is accommodated in the reflection member 24 with the minute projections 27 facing the bottom side. The LED light source 1 causes the upper protruding portion 12 and the lower protruding portion 13 to be in contact with the upper and lower portions of the concave surface 25 so that the light emitting surface 14a falls within the region of the concave surface 25 of the light guide member 22, and the positioning protrusions 11, 11
The positioning surfaces 11a, 11a are brought into contact with the side surfaces adjacent to the concave surface 25, and are housed in the mounting concave portion 28 in a state of being in close contact therewith. At this time, the fixing of the LED light source 1 to the reflecting member 24 was performed by forming a convex ridge engaging projection 29 provided on the back surface of the reflecting case 8 of the LED light source 1 in the mounting concave portion 28 as shown in FIG. This is performed by engaging with the engagement hole 30.

Thus, as shown in FIG. 6, the LED light source 1 has the upper surface of the reflection case 8 flush with the surfaces of the light guide member 22 and the reflection member 24, and the lower surface of the reflection case 8 has the reflection member 24. Is positioned and fixed to the reflecting member 24 so as to be flush with the bottom surface of the light emitting element.

In the LED light source 1, the engaging protrusion 29 is engaged with the engaging hole 30 of the reflecting member 24 so that the reflecting member 24
However, the present invention is not limited to the above configuration, and any configuration may be used as long as the LED light source 1 can be positioned and fixed with respect to the reflecting member 24.

As shown in FIG. 6, the surface light-emitting device 21 having the above-described structure is a liquid crystal panel (display panel) indicated by a dashed line.
35 is disposed in close contact with the rear surface side. And each LED
When 2A and 2B are driven simultaneously and emit light, the light emitting surface 14
From a, white light is incident on the concave surface 25 forming the light introduction surface of the light guide member 22. When the light is incident on the concave surface 25 forming the light introducing surface, the light is reflected toward the light emitting surface 26 by the minute projections 27 formed on the inner wall surface of the reflecting member 24 and the light guiding member 22. As a result, the light exit surface 26 of the light guide member 22 emits surface light uniformly over the entire surface, and the liquid crystal panel 35 is irradiated with uniform light from the back surface side.

Next, FIG. 8 is a view showing an embodiment of the surface light emitting device on which the LED light source 1 is mounted. In the drawing, the same components as those of the surface light emitting device of FIG. 6 are denoted by the same reference numerals, and description thereof will be omitted.

The surface emitting device 31 according to the present embodiment includes the reflecting member 3
4 is the same as the surface light emitting device of FIG.
The reflecting member 34 is formed in a frame shape with open upper and lower surfaces. The light guide member 22 is accommodated in the frame of the reflection member 34 with the front and back surfaces reversed from the surface light emitting device 21 shown in FIG. 6, that is, with the surface on which the minute projections 27 are formed facing upward. Accordingly, the mounting recess 28 in which the LED light source 1 is mounted is formed at a position symmetrical to the surface light emitting device 21 shown in FIG. 6, and at a position corresponding to the upper right corner of the reflecting member 24 in FIG.

In the LED light source 1, the upper protruding portion 12 and the lower protruding portion 13 are brought into contact with the upper and lower portions of the concave surface 25 so that the light emitting surface 14a is within the area of the concave surface 25 of the light guide member 22, and the LED light source 1 is positioned. Positioning surfaces 11a of the projections 11, 11
11a is accommodated in the mounting concave portion 28 in a state of being brought into close contact with the side surface adjacent to the concave surface 25. At that time, the positioning and fixing of the LED light source 1 with respect to the reflecting member 34 is performed by engaging the engaging projection 29 of the reflecting case 8 with the engaging hole 30.

As shown in FIG. 8, the surface light emitting device 31 having the above configuration is disposed in close contact with the front surface of the liquid crystal panel 35 indicated by a dashed line. Then, when the LEDs 2A and 2B are simultaneously driven and emit light, white light is incident from the light emitting surface 14a to the concave surface 25 forming the light introduction surface of the light guide member 22.
When light is incident on the concave surface 25 forming the light introducing surface, the light is reflected toward the light emitting surface 26 by the inner wall surface of the reflecting member 34 and the minute projections 27 formed on the light guiding member 22. Thus, the light exit surface 26 of the light guide member 22 emits surface light uniformly over the entire surface, and irradiates the surface of the liquid crystal panel 35 with uniform light.

According to the above configuration, other components except the reflection member 34, that is, the LED light source 1 and the light guide member 22 can be used also as those shown in FIG.

In the above configuration, when the surroundings are bright and sufficient external light can be obtained, the external light can be used without driving the LEDs 2A and 2B to emit light. In that case, the external light irradiates the surface of the liquid crystal panel from the upper surface of the light guide member 22 to the space between the minute protrusions 27 in FIG.

As described above, in the LED light source of the above embodiment, the light emitting surface 14 a faces the concave surface 25 of the light guide member 22,
The upper protruding portion 12 and the lower protruding portion 13 of the reflection case 8 are concave
5 and the positioning surface 11a of the positioning protrusion 11
Are housed in the reflection member 24 in a state of contacting the side surfaces adjacent to the concave surface 25 of the light guide member 22, respectively.
The light emitted from the EDs 2A and 2B can be closely attached to the concave surface 25 without leaking light to the outside, so that an optimal light source can be obtained, for example, as a surface emitting device used as a light source for illumination of a liquid crystal panel. At this time, the reflection case 8
Since the dimensions of the EDs 2A and 2B in the optical axis direction are small and thin, the projections of the corners when the EDs 2A and 2B are accommodated in the reflection member 24 are small, and compact mounting can be performed.

According to the surface light emitting device using the LED light source, since the LED light source 1 is provided with the light emitting surface 14a facing the corner of the light guide member 22, the light guide member is provided within a range of 90 °. The light may be incident on the light guide member 22, and it is only necessary to provide the light at least at one of the corner portions of the light guide member 22. Surface light emission can be performed. At that time, as described above, the LED light source 1 can be attached in a state in which the LED light source 1 is in close contact with the corner portion of the light guide member 22.
A compact surface emitting device can be obtained.

The corner portion of the light guide member 22 on which the LED light source 1 is disposed is a light introduction surface forming a concave surface 25 cut out at a predetermined curvature, so that even when an LED having a narrow directivity is used. The light from the LED light source 1 can efficiently enter the light guide member 22 through the concave surface 25 over a wide range, and the incidence efficiency on the light guide member 22 can be increased as compared with the related art.

The fine projections 27 formed on one surface of the light guide member 22 are formed in large numbers to make the incident light bright and uniform, and the surface is mirror-finished.
The light guide member 22 having no reflection of light and high reflection efficiency can be configured.

Microprojections 27 formed on light guide member 22
Is as small as 50 to 100 μm in diameter, so small that it cannot be discerned even with the naked eye. In addition, since the surface of each minute projection 27 is a mirror surface, it is transparent without scattering. Thus, even when used as a front light of the liquid crystal panel 35 with the configuration shown in FIG. 8, light is emitted to the liquid crystal panel 35 side, and the liquid crystal display looks clear, bright and uniform, and sufficient visibility is obtained. Can be.

By the way, the LED in the above embodiment
Light source 1 has two colors L of blue LED 2A and yellow LED 2B.
ED2 is provided to emit white light.
As shown in FIG. 9, a configuration may be employed in which one LED is provided on the element mounting pattern 4 in the concave window portion 9 so as to emit monochromatic light using the common conductive pattern of FIG. 1. Specifically, for example, a green LED 2D made of a material such as InGaAlP is die-bonded onto the element mounting pattern 4 in the concave window portion 9, and the + electrode on the upper surface and the connection pattern 6 are connected.
If wire connection is made by wire bonding between a and
Green light is emitted from the light emitting surface 14a of the LED light source 1.

As described above, in the pattern configuration shown in FIG. 1, the LEDs 2 can be mounted at two places.
If the LED 2 is mounted at the location, the LED light source 1 of monochromatic light is obtained, and the LED (the blue LED 2A, the yellow LED 2) is provided at two locations.
B) By mounting 2, a white light LED light source 1 can be obtained.

As a configuration for emitting white light, as shown in FIG. 10, a configuration in which three color LEDs of blue LED 2A, red LED 2C and green LED 2D are provided on the element mounting pattern 4 in the concave window portion 9 is also possible. Good. At this time, the external terminal 5 includes one anode terminal 5a to which the LEDs 2A, 2C, and 2D are commonly connected, and one LED 2A, 2C, and 2D.
It is composed of three cathode terminals 5b, 5c, and 5d that are connected to each other, and is wired and connected so that the LEDs 2A, 2C, and 2D emit light simultaneously.

In the above embodiment, the LED light source 1 is provided at one corner of the light guide member 22. However, the LED light source 1 is provided at a plurality of corners of the light guide member 22. You may. At this time, it is most preferable that a corner portion of the light guide member 22 on which the LED light source 1 is disposed has a concave surface 25 cut out at a predetermined curvature. Thereby, the luminance can be further improved as compared with the case where the LED light source 1 is provided at one position of the light guide member 22. In the illustrated example, the light guide member 2
Although 2 has been described as being formed in a rectangular plate shape, for example, any one formed in a square shape such as a square or a polygon can be used.

[0054]

As is apparent from the above description, according to the surface-emitting lighting device of the present invention, the LED light source is provided at at least one of the corners of the light guide member, so that the LED light source can be mounted on the light guide member more than before. And uniform surface light emission can be performed without the occurrence of dark places. At this time, the LED light source can be attached in a state in which the LED light source is in close contact with the corner portion of the light guide member, so that the surface light emitting device of the front light of the liquid crystal panel of various portable devices can be configured compactly.

The corners of the light guide member on which the LED light source is disposed are formed as light introduction surfaces cut out at a predetermined curvature. Can be efficiently incident over a wide range of the light guide member, and the incidence efficiency on the light guide member can be increased as compared with the related art.

The fine projections formed on one surface of the light guide member are formed in large numbers to make the incident light bright and uniform, and the surface is mirror-finished, so that there is no scattering of light. Thus, a light guide member having good reflection efficiency can be formed.

The microprojections formed on the light guide member are so small that they cannot be discerned by the naked eye, and the surfaces of the microprojections are mirror-finished and transparent without scattering, so that they can be used as front lights for liquid crystal panels. Even so, light is emitted to the liquid crystal panel side, and the liquid crystal display looks clear, bright and uniform, and sufficient visibility can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing an L used in a surface light source device according to the present invention;
Perspective view of implementation of ED light source

FIG. 2 is a plan view of the LED light source.

FIG. 3 is an equivalent circuit diagram of the LED light source.

FIG. 4 is a chromaticity diagram showing the emission color of each LED of the LED light source used in the surface light source device of the present invention and white light obtained by simultaneous emission of each LED.

5A is a diagram showing an example of a surface light emitting device equipped with an LED light source. FIG.

FIG. 6 is a sectional view taken along line II of FIG.

FIG. 7 is a partially enlarged plan sectional view of the same surface light emitting device.

FIG. 8 is a diagram showing an embodiment of a surface emitting device according to the present invention.

FIG. 9 is a plan view showing another example of the LED light source used in the surface light source device of the present invention.

FIG. 10 is a plan view showing another example of the LED light source used in the surface light source device of the present invention.

FIG. 11 is a diagram showing a configuration example of a conventional surface light emitting device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... LED light source, 2 ... LED, 8 ... Reflection case, 9 ... Concave window part, 11 ... Positioning protrusion, 11a ... Positioning surface, 12
... Upper projecting portion, 13 ... Lower projecting portion, 21, 31 ... Surface emitting device, 22 ... Light guide member, 24, 34 ... Reflecting member, 25 ... Concave surface (light introducing surface), 26 ... Light emitting surface, 27 ... Microscopic Protrusions.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-9-298008 (JP, A) JP-A-7-320514 (JP, A) JP-A-9-265823 (JP, A) JP-A-10-1998 247412 (JP, A) JP-A-10-255530 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G09F 13/18 F21V 8/00 G09F 9/00

Claims (1)

(57) [Claims] 1. A light introducing surface cut at a predetermined curvature is reduced.
Are formed at one corner and introduced from the light introduction surface.
A square plate-like shape that emits light from the front surface or the back surface that forms the light exit surface
A light guide member, an LED that emits light of a predetermined color, and a light guide surface.
A recessed window is formed through the opening, and is accommodated in the area of the light introducing surface.
The LED is housed in the concave window portion so that
At an angle approximately equal to the angle between the surfaces adjacent to the introduction surface
Positioning surfaces are formed on both sides of the concave window portion,
A protrusion having substantially the same curvature as the light introduction surface is located between the positioning surfaces.
The vertical position of the light introducing surface at the upper and lower outer peripheral portions of the concave window portion
LED light source provided with a reflection case formed opposite to the light source
And comprising bets, the LED light source, the light emitting surface facing to the light inlet surface, before
The protrusion is in contact with a vertical position of the light introduction surface, and
The positioning surfaces are in contact with the surfaces adjacent to the light
The light guide member has a mirror surface on a surface opposite to the light exit surface.
Hemispherical micro-projections or hemispheres with roughened surface
Small protrusions are in inverse proportion to the distance from the LED light source.
The upper and lower surfaces that reflect incident light in a predetermined direction are open
A reflecting member, wherein the light guiding member is located in the reflecting member.
With the LED light source with the micro projections facing the upper surface side
A surface light-emitting device, which is housed and fixed to a device.