JP2003109416A - Surface light source - Google Patents

Abstract

PROBLEM TO BE SOLVED: To emit light having uniform brightness distribution with the small number of light-emitting devices in the surface light source having a solid light- emitting device such as an LED. SOLUTION: A solid light-emitting device 14 is arranged on one end side of a prism sheet 11 in which a plurality of flex prism parts 12 being formed in a wave shape along the width direction are arranged on a rear surface 11b, light emitted from the solid light-emitting device 14 is refracted in the width direction of the prism sheet 11 from the flex incident surface 12a which is one side surface of the reflex prism part 12, made incident in a plurality of flex prism parts 12 of the prism sheet 11, the light incident is diffused in the width direction of the prism sheet 11 by the flex refraction surface 12b which is the other side surface of the flex prism part 12, refracted toward the front surface 11a of the prism sheet 11, and goes out in a uniform intensity from the whole region of the front surface 11a of the prism sheet 11.

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 used as an illumination light source of a liquid crystal display device.

[0002]

2. Description of the Related Art Conventionally, as a surface light source used for an illumination light source of a liquid crystal display device, a light guide plate which has an incident end face at one end and guides light incident from the incident end face to emit the light from the front face is provided. A structure in which a cold cathode tube having a length extending over the entire length of the entrance end surface of the light guide plate is arranged so as to face the entrance end surface is widely used.

However, in this surface light source, the light emitted from the cold cathode fluorescent lamp can be made incident on the light guide plate from the entire area of the incident end face thereof, and the light having a uniform brightness distribution can be emitted from the front face of the light guide plate. However, on the other hand, since the cold cathode fluorescent lamp has a short life, the cold cathode fluorescent lamp has to be frequently replaced, and therefore the maintenance cost increases.

Therefore, recently, instead of the cold cathode tube, a surface light source having a solid light emitting element such as an LED (light emitting diode) has come to be used.

FIG. 13 is a perspective view of a conventional surface light source having a solid-state light emitting element, and here, one solid-state light emitting element 2 is used.
Is arranged so as to face the center portion in the length direction of the incident end face 1a of the light guide plate 1.

In this surface light source, since the solid-state light-emitting element 4 has a semi-permanent life, it is almost unnecessary to replace the light-emitting element 4, and therefore the maintenance cost can be reduced.

[0007]

However, in the conventional surface light source shown in FIG. 13, the incident light to the light guide plate 1 is made to face the central portion in the length direction of the incident end face 1a of the light guide plate 1. Since the light is emitted from the solid-state light emitting element 2 arranged, the light incident from the incident end face 1a does not spread evenly over the entire area of the light guide plate 1, and therefore, of the light emitted from the front face of the light guide plate 1, The brightness of the emitted light from the region hatched in FIG. 13 is low, and the emitted light having a uniform brightness distribution cannot be obtained.

If the number of the solid-state light emitting elements 4 is increased and the light emitting elements 4 are arranged at close intervals along the lengthwise direction of the incident end face 1a of the light guide plate 1, the incident end faces of the light guide plate 1 are arranged. Although light can be made incident from the entire area of 1a and light having a uniform luminance distribution can be emitted from the front surface of the light guide plate 1, if the number of light emitting elements is increased, the cost is increased and the power consumption is increased. Will end up.

It is an object of the present invention to provide a surface light source having a solid-state light emitting element, which can emit light having a uniform luminance distribution with a small number of light emitting elements.

[0010]

According to the surface light source of the present invention, a plurality of bending reflection surfaces or bending refraction surfaces that are bent in a wave shape along one direction are formed on one of the front and rear surfaces, and the surface light source is formed in the one direction. The light incident on the plurality of bending reflection surfaces or bending refraction surfaces from the direction intersecting with each other is refracted or reflected from the bending reflection surface or the bending refraction surface toward the other surface, and the light is emitted from the other surface. At least one that is disposed on one end side of the light diverting member that intersects the one direction of the light diverting member, and emits light toward the light diverting member.
It is characterized by comprising three solid state light emitting devices.

According to this surface light source, the light emitted from the solid-state light-emitting element is diffused by the plurality of bending reflecting surfaces or bending refracting surfaces formed on one surface of the light diverting member, and the light diverting direction is generated. Refracted or reflected towards the other side of the member,
Since the light is emitted from the other surface of the light diverting member,
Light with uniform brightness can be emitted with a small number of light emitting elements.

As described above, the surface light source of the present invention includes a light diverting member having a plurality of oblong bending reflection surfaces or bending refraction surfaces that are bent in a wave shape on one of the front and rear surfaces, and And at least one solid-state light emitting element that emits light toward the light diverting member, the light being emitted from the solid-state light emitting element. By diffusing by a plurality of bending reflection surfaces or bending refraction surfaces of the directing member to be refracted or reflected toward the other surface of the light redirecting member, and by emitting the light from the other surface of the light redirecting member. It is possible to emit light having a uniform luminance distribution with a small number of light emitting elements.

In the surface light source of the present invention, the light diverting member has, for example, a plurality of bending prism portions that are bent in a wave shape along one direction on one of the front and rear surfaces, and these bending prism portions are formed. One side surface of the both side surfaces facing the arrangement side of the solid state light emitting element is a bent incident surface on which the light emitted from the solid state light emitting element is incident, and the other side surface is the light incident from the bent incident surface. Is preferably a prism sheet having a bending refraction surface that is refracted toward the other surface, and in that case, the solid-state light-emitting element emits light in a direction along a surface on which the bending prism portion of the prism sheet is formed. It may be arranged so as to emit light.

When the prism sheet is used as the light diverting member as described above, the prism sheet has a surface on which the bent prism portion is formed and has an incident end face at one end, and guides light incident from the incident end face. It is more preferable to dispose a light guide plate that emits from a surface facing the prism sheet and to dispose the solid state light emitting element so as to face an incident end surface of the light guide plate.

Further, the light diverting member has an incident end face at one end, and a plurality of bending grooves bent in a wave shape along one direction are formed on one of the front and rear faces, and these bending grooves are formed. Of both side surfaces, one side surface facing the incident end surface side may be a deflecting light guide plate that is a bending reflection surface that reflects light incident from the incident end surface toward the other surface, and in that case,
The solid state light emitting device may be arranged so as to face the incident end face of the deflection light guide plate.

[0016]

1 to 4 show a first embodiment of the present invention. FIG. 1 is a perspective view of a surface light source, FIG. 2 is a side view of the surface light source, and FIG. FIG. 4 is a bottom view of a prism sheet provided as a light diverting member of a light source, and FIG. 4 is a schematic view showing diffusion of light by the prism sheet.

As shown in FIGS. 1 and 2, the surface light source 10 of this embodiment includes a prism sheet 11 having a plurality of bent prism portions 12 formed on one surface thereof and bent in a wave shape along one direction. A reflection plate 13 disposed so as to face the surface of the prism sheet 11 on which the bent prism portion 12 is formed.
And one solid-state light-emitting device 14 that is disposed on one end side of the prism sheet 11 in a direction intersecting the one direction (the length direction of the bending prism portion 12) and emits light toward the prism sheet 11. It consists of

The prism sheet 11 is made of a transparent resin such as acrylic resin, and its front and rear surfaces 11a, 1
The plurality of bent prism portions 12 are formed on one surface of 1b, for example, the rear surface 11b, and the other surface, the front surface 11a, is a flat surface.

As shown in FIGS. 1 and 3, the plurality of bent prism portions 12 are formed to have a length that extends over the entire width of the prism sheet 11.
Has a triangular cross-sectional shape bent in a sinusoidal (sin curve) shape along the width direction of, and one side surface of the both side surfaces facing the arrangement side of the solid-state light-emitting element 14 is , The bending incident surface 12a on which the light emitted from the solid-state light-emitting element 14 is made incident, and the other side surface makes the prism sheet 11 receive the light incident from the bending incident surface 12a.
It is a bending and refracting surface 12b that is refracted toward the front surface 11a.

The bent incident surface 12a is a steeply inclined surface which is nearly vertical to the front surface 11a of the prism sheet 11, and the bent refracting surface 12b is relative to a normal line (not shown) of the front surface 11a of the prism sheet 11. The angle of inclination is larger than that of the curved incident surface 12a, and the curved incident surface 1 is
The angle of 2a with respect to the normal is set in the range of 5 to 15 degrees, and the angle of the bending and refracting surface 12b with respect to the normal is set in the range of 15 to 60 degrees.

The plurality of bending prism portions 12 are
The prism sheet 11 is formed with a certain pitch in the length direction of the prism sheet 11 with a space between each, and the portion between the bent prism portions 12 on the rear surface 11b of the prism sheet 11 is formed on the prism sheet 11. It is a surface parallel to the front surface 11a or having an inclination close to it.

The surface light source 10 of this embodiment is behind a transmissive liquid crystal display element (active matrix type or simple matrix type liquid crystal display element) 30 shown by phantom lines (two-dot chain line) in FIGS. In the figure, for the sake of convenience, the pitch of the plurality of bending prism portions 12 of the prism sheet 11 and the bending prism portion 1 are illustrated.
Although the shape of No. 2 is greatly exaggerated and shown, the pitch of the plurality of bending prism portions 12 is set to be equal to or smaller than the pixel pitch of the liquid crystal display element 30,
Further, the bending prism portion 12 is formed in a shape in which waves having a width equal to or smaller than the pitch of the plurality of bending prism portions 12 are repeated continuously.

The reflecting plate 13 is provided on the rear side of the prism sheet 11 with one end side of the prism sheet 11 (solid-state light emitting element 14) at a distance from the tops of the plurality of bending prism portions 12 of the prism sheet 11. (The arrangement side of the prism sheet) is gradually inclined toward the other end side, and the end portion facing the other end side of the prism sheet 11 is provided with the bent prism portion 12 of the most other end side of the prism sheet 11. It is placed in contact with the top.

Although the structure of the solid-state light-emitting element 14 is not shown, for example, a red LED that emits red light is used.
(Light emitting diode) and a green LED emitting green light,
Blue LEDs that emit blue light are arranged side by side,
These LEDs are molded by the transparent resin and emit white light obtained by mixing the lights of the three colors of red, green and blue emitted by the LEDs.

The solid-state light-emitting element 14 is located at one end of the prism sheet 11 at the center of the prism sheet 11 in the width direction, and the prism sheet 1 is provided.
1 is arranged so as to face the space between the reflection plate 13 and the reflection plate 13, and emits light in a direction along the rear surface 11b of the prism sheet 10 on which the bent prism portion 12 is formed.

The surface light source 10 includes the solid-state light emitting element 14 described above.
Is emitted from the front surface 10a of the prism sheet 11 through the prism sheet 11, and the light emitted from the solid-state light emitting element 14 in the direction along the rear surface 11b of the prism sheet 10 is indicated by an arrow in FIG. As indicated by the lines, the bending surface 12a of each of the plurality of bending prisms 12 on the rear surface 11b of the prism sheet 11 is directly or directly connected to the reflecting plate 1.
It is reflected by 3 and enters.

The light incident on the bent incident surface 12a of the plurality of bent prism portions 12 passes through the interface between the bent incident surface 12a and the outside air (air between the prism sheet 11 and the reflection plate 13), and As shown in FIG. 4, the bent incident surface 1 is bent in accordance with the incident angle to each part of the interface bent in a wave shape.
The light is refracted at various refraction angles in the length direction of 2a, that is, in the width direction of the prism sheet 11, diffuses in the width direction of the prism sheet 11, and enters the bending prism portion 12.

Then, as shown in FIG. 4, the light incident on the plurality of bending prism portions 12 is totally reflected by the interface between the bending and refracting surface 12b of the bending prism portion 12 and the outside air, and the prism sheet. 11 is refracted toward the front surface 11a of the prism sheet 11, and is further diffused in the width direction of the prism sheet 11 by refraction at the interface that is bent in a wave shape,
The light spreads over the entire width of the prism sheet 11 and is emitted from the entire area of the front surface 11a of the prism sheet 11 with uniform intensity.

That is, the surface light source 10 diffuses the light emitted from the solid-state light-emitting element 14 in the width direction of the prism sheet 11 by the plurality of bent prism portions 12 formed on the rear surface 11b of the prism sheet 11. Then, the light is refracted toward the front surface 11a of the prism sheet 11, and the light is emitted from the entire area of the front surface 11a of the prism sheet 11 with a uniform intensity. Therefore, with a small number of light emitting elements, a uniform luminance distribution is obtained. Light can be emitted.

Moreover, in this embodiment, the bending and refracting surfaces 12 of the plurality of bending prism portions 12 of the prism sheet 11 are used.
Since the inclination angle of b (the angle with respect to the normal to the front surface 11a of the prism sheet 11) is in the range of 15 to 60 degrees, the light is emitted from the solid-state light-emitting element 14 and the prism sheet 1
A plurality of bending prism portions 12 of one bending incident surface 12a
The light incident from FIG.
As shown in FIG. 1, the prism sheet 1 is refracted toward a direction near the normal to the front surface 11a of the prism sheet 11 when viewed from the side surface direction of the prism sheet 11,
The front brightness of the light emitted from the front surface 11a of No. 1 can be increased.

The front surface 11 of the prism sheet 11
The light emitted to a enters the transmissive liquid crystal display element 30 from its rear surface, passes through the liquid crystal display element 30, and is emitted to the front side.

Therefore, by disposing the surface light source 10 behind the transmissive liquid crystal display element 30 as shown in FIG. 1, the brightness of the screen is uniform and there is no unevenness in brightness, and the front brightness is high. A liquid crystal display device of display quality can be obtained.

Further, since the surface light source 10 has the reflection plate 13 arranged on the rear side of the prism sheet 11, the external light incident from the front side of the prism sheet 11 is made to have a thickness of the prism sheet 11. And is reflected by the reflection plate 13, and the reflected light is transmitted again in the thickness direction of the prism sheet 11 and its front surface 11a.
Therefore, the liquid crystal display device is provided with both a reflective display utilizing external light which is the light of the environment of use and a transmissive display utilizing the illumination light from the surface light source 10. Can be done.

In the surface light source 10 of the above embodiment, one solid-state light emitting element 14 is arranged on one end side of the prism sheet 11, but the number of the solid-state light emitting element 14 is not limited to one. The solid state light emitting elements may be arranged side by side at an appropriate interval in the width direction of the prism sheet 11, and in that case, similarly to the second embodiment described above, a solid state light emitting element that emits red light, You may arrange | position the solid-state light emitting element which emits green light, and the solid-state light emitting element which emits blue light side by side.

FIGS. 5 and 6 show a second embodiment of the present invention. FIG. 5 is a perspective view of a surface light source, and FIG. 6 is a schematic view showing light diffusion by a prism sheet of the surface light source. .

The surface light source 10a of this embodiment has a solid-state light emitting element 14R composed of a red LED and a solid-state light emitting element 14B composed of a green LED on one end of the prism sheet 11.
One solid light emitting element 14B composed of a blue LED,
The prism sheets 11 are arranged side by side at appropriate intervals in the width direction of the prism sheet 11, and the other configurations are the same as those of the surface light source 10 of the first embodiment.

The surface light source 10a is the solid-state light emitting device 1 described above.
Similarly to the surface light source 10 of the first embodiment, a plurality of bent prism portions 1 formed on the rear surface 11b of the prism sheet 11 emit light emitted from 4R, 14G, and 14B, respectively.
2, the prism sheet 11 is diffused in the width direction and refracted toward the front surface 11a of the prism sheet 11,
Light is emitted from the entire front surface 11a of the prism sheet 11 with uniform intensity.

The surface light source 10a includes a solid light emitting element 14R for emitting red light R, a solid light emitting element 14G for emitting green light G, and a solid light emitting element 14B for emitting blue light B. , These solid state light emitting devices 14R,
The light emitted from 14G and 14B is emitted from the entire front surface 11a of the prism sheet 11 with uniform intensity. Therefore, the solid-state light-emitting devices 14R, 14G, and 14B are turned on at the same time, so that the front surface of the prism sheet 11 is illuminated. It is possible to emit white light of uniform brightness in which three colors of red, green, and blue are uniformly mixed, from the entire area of 11a.

Further, the surface light source 10a is arranged such that the solid-state light emitting elements 14R, 14G and 14B are sequentially turned on so that red light is emitted from the front surface 11a of the prism sheet 11.
It is possible to sequentially emit light of three colors of green and blue, and thus it can be used as a surface light source of a field sequential liquid crystal display device.

7 and 8 show a third embodiment of the present invention, FIG. 7 is a perspective view of a surface light source, and FIG. 8 is a side view of the surface light source.

The surface light source 10b of this embodiment includes a prism sheet 11 and a reflecting plate 13 of the surface light source 10 of the first embodiment.
Has an incident end face 15a at one end thereof, and guides the light incident from the incident end face 15a to guide the prism sheet 11
The light guide plate 15 which is emitted from the front surface 15b facing the light guide plate 15 is arranged, and the solid state light emitting element 14 is arranged so as to face the center portion of the incident end surface 15a of the light guide plate 15 in the length direction. This is the same as the surface light source 10 of the first embodiment.

The light guide plate 15 is the prism sheet 1.
The front surface 15b facing 1 is formed into a flat surface, and the rear surface 15
c is a wedge-plate-shaped transparent plate made of acrylic resin or the like formed on an inclined surface that is inclined so as to approach the front surface 15b from one end to the other end. The end face with the larger width is the entrance end face 15a, and the front face 15b is the exit face of the light incident from the entrance end face 15a.

The light guide plate 15 has a front surface 15
b is disposed on the rear side of the prism sheet 11 so as to be in contact with or close to the tops of the plurality of bent prism portions 12 on the rear surface 10b of the prism sheet 11, and the reflection plate 13
Is disposed on the rear side of the light guide plate 15 so as to come into contact with the rear surface 15c of the light guide plate 15.

The surface light source 10b is configured such that the light emitted from the solid-state light emitting element 14 is guided by the light guide plate 15 and is incident on the plurality of bent prism portions 12 formed on the rear surface 11b of the prism sheet 11. Light emitted from the solid-state light-emitting element 14 enters the light guide plate 15 from its incident end face 15a, and as shown by the arrow in FIG.
Total reflection at the interface between the front surface 15b of the light guide plate 15 and the outside air (air between the prism sheet 11 and the reflection plate 13) and the reflection plate 13 arranged in contact with the rear surface 15c of the light guide plate 15.
The light guide plate 15 is guided through the light guide plate 15 by the reflection of light at an angle of incidence smaller than the critical angle of total reflection and enters the interface between the front surface 15b of the light guide plate 15 and the outside air, and the light is transmitted through the interface. Is emitted to the front surface 15b.

The light emitted to the front surface 15b of the light guide plate 15 is applied to the plurality of bent prism portions 12 formed on the rear surface 11b of the prism sheet 11 from the bent incident surface 12a in the length direction, that is, Prism sheet 11
And is incident in the bending prism portion 12 in the width direction of
The bending and refracting surface 12b of the prism sheet 11 further diffuses in the width direction of the prism sheet 11, and the front surface 1 of the prism sheet 11
The light is refracted toward 1a and is emitted from the entire front surface 11a of the prism sheet 11 with uniform intensity.

Therefore, according to this surface light source 10b,
Light with a uniform luminance distribution can be emitted with a small number of light emitting elements.

Moreover, in the surface light source 10b of this embodiment, the light emitted from the solid state light emitting element 14 is guided by the light guide plate 15 and emitted to the front surface 15b of the light guide plate 15, and the light is emitted from the prism sheet 11. Since the light is emitted to the plurality of bent prism portions 12, the light emitted from the solid state light emitting device 14 can be efficiently made to enter the plurality of bent prism portions 12 of the prism sheet 11.

That is, the light emitted from the solid-state light emitting element 14 has a certain divergence angle in the width direction and the thickness direction of the prism sheet 11, but the first light shown in FIGS. In the surface light source 10 according to the embodiment, the light emitted from the solid-state light emitting element 14 is the prism sheet 1
Since the light travels in the space between the reflection plate 13 and the reflection plate 13 that is inclined to the rear side, a part of the light leaks to both sides of the space and is wasted.

On the other hand, in the surface light source 10b of this embodiment, the light emitted from the solid-state light-emitting element 14 is guided by the light guide plate 15 and is emitted to the front surface 15b of the light guide plate 15, so that the light guide plate 15 is provided. Of the light incident from the incident end surface 15a, the light traveling toward the side surface of the light guide plate 15 is also
At the interface between the side surface of the light guide plate 15 and the outside air, the light is totally reflected and guided inside the light guide plate 15, and finally emitted from the front surface 15b of the light guide plate 15 and the plurality of bent prism portions 12 of the prism sheet 11. Incident on.

Therefore, the surface light source 10b of this embodiment is
Light emitted from the solid state light emitting element 14 can be efficiently incident on the plurality of bent prism portions 12 of the prism sheet 11, and high-intensity light can be emitted from the front surface 11a of the prism sheet 11, and therefore, the liquid crystal display element. The display of 30 can be brightened.

Further, in the surface light source 10b of this embodiment, since the reflecting plate 13 is arranged on the rear side of the light guide plate 15, the liquid crystal display in which the surface light source 10b is arranged behind the transmissive liquid crystal display element 30. It is possible to cause the device to perform both a reflective display using external light and a transmissive display using illumination light from the surface light source 10b.

In this embodiment, the reflection plate 13 is arranged in contact with the rear surface 15c of the light guide plate 15, but the reflection plate 13 is arranged close to the rear side of the light guide plate 15. It may be arranged, and even in that case, of the light guided in the light guide plate 15, the light directed to the rear surface 15c of the light guide plate 15 is transferred to the rear surface 15c of the light guide plate 15 (the light guide plate 15).
The light can be guided through the light guide plate 15 by being totally reflected at the interface between the air) and the air between the reflection plate 13.

The light guide plate 15 has a rear surface 15c.
In addition, a plurality of grooves having a triangular cross-sectional shape along the width direction of the light guide plate 15 may be formed in parallel with each other. With the light guide plate 15 having such a configuration, the light guide plate 15 can be formed.
Of the light guided inside, the light traveling toward the rear surface 15c of the light guide plate 15 is totally reflected at the interface between the side surface of the groove and the outside air (air in the groove), and effectively from the front surface 15b of the light guide plate 15. It can be emitted.

Also in the surface light source 10b of this embodiment, the number of solid-state light emitting elements 14 is not limited to one, and a plurality of solid-state light emitting elements may be arranged side by side at appropriate intervals in the width direction of the prism sheet 11. Good.

In the first to third embodiments described above, the plurality of bending prism portions 12 of the prism sheet 11 are formed into a sinusoidal shape, but the plurality of bending prism portions 12 are formed as follows. The shape is not limited to a sine wave, and may be formed into a shape that bends into a circle, an elliptic wave, a triangular wave, or the like.

9 to 11 show a fourth embodiment of the present invention. FIG. 9 is a perspective view of a surface light source, FIG. 10 is a side view of the surface light source, and FIG. 11 is a light transformation of the surface light source. It is a bottom view of the turning light guide plate provided as a facing member.

As shown in FIGS. 9 and 10, the surface light source 20 of this embodiment has an incident end face 21a at one end and is bent in a wave shape along one direction on one of the front and rear faces 21b and 21c. Deflection light guide plate 21 in which a plurality of bent grooves 22 are formed.
A reflection plate 23 arranged to face the surface of the deflection light guide plate 21 on which the bending groove 22 is formed; and the deflection light guide plate 2
One solid-state light emitting element 24, which is arranged at one end side in a direction intersecting the one direction (the lengthwise direction of the bent groove 22) and emits light toward the turning light guide plate 21. .

The deflecting light guide plate 21 has a wedge plate shape in which a front surface 21b is formed as a flat surface and a rear surface 21c is formed as an inclined surface which is inclined so as to approach the front surface 21b from one end to the other end. It is a transparent plate made of acrylic resin or the like, and one of the two end faces having the larger width between the front and back faces is the incident end face 21a, and the front face 21b is the exit face of the light incident from the incident end face 21a. The plurality of bent grooves 22 are formed on the rear surface 21c of the deflection light guide plate 21.

The plurality of bent grooves 22 are shown in FIG. 9 and FIG.
As shown in FIG. 1, a cross-sectional shape bent in a sinusoidal shape along the width direction of the deflection light guide plate 21 and having a triangular shape is formed over the entire width of the deflection light guide plate 21. Of the both side surfaces of these bent grooves 22, one side surface facing the incident end surface 21a side is the incident end surface 2
It is a bent reflection surface 22a that reflects the light incident from 1a toward the front surface 21b of the turning light guide plate.

The bent reflection surface 22a is formed by the bent groove 22.
Is an inclined surface that is inclined toward the incident end surface 21a side from the bottom of the curved light guide plate 21 toward the front surface 21b of the turning light guide plate 21, and the angle of the curved reflection surface 22a with respect to the normal line (not shown) of the front surface 21b of the curved reflection surface 22a. Is set in the range of 15 to 60 degrees. In addition, the bent reflection surface 2 of the bent groove 22.
The side surface on the side opposite to 2a is a steeply inclined surface that is inclined at an angle of 5 to 15 degrees on the side opposite to the curved reflection surface 22a with respect to the normal line.

The plurality of bent grooves 22 are formed at regular intervals in the lengthwise direction of the deflection light guide plate 211 with an interval between each of the bent grooves 22.

The surface light source 10 of this embodiment is behind the transmissive liquid crystal display element (active matrix type or simple matrix type liquid crystal display element) 30 shown by the phantom line (two-dot chain line) in FIGS. The pitch of the plurality of bending grooves 22 and the shape of the bending grooves 22 of the deflection light guide plate 21 are greatly exaggerated in the drawing for convenience sake, but the pitch of the plurality of bending grooves 22 is illustrated. Is
The pixel pitch of the liquid crystal display element 30 is set to be equal to or smaller than the pixel pitch, and the bending groove 22 has a shape in which waves having a width equal to or less than the pitch of the plurality of bending grooves 22 are continuously repeated. Has been formed.

The reflection plate 23 is arranged on the rear side of the deflection light guide plate 21 so as to be in contact with the rear surface 21c.

Further, the solid-state light emitting device 24 is, for example,
The solid-state light-emitting device 24 is a light-emitting device that emits the same white light as the solid-state light-emitting device 14 of the first embodiment described above.
It is arranged laterally of the incident end face 21a of the deflection light guide plate 21 so as to face the center portion in the length direction of the incident end face 21a.

The surface light source 10 includes the solid-state light emitting device 24.
Is emitted from the front surface 21b of the light guide plate 21 through the deflection light guide plate 21.
The emitted light from the incident light is incident on the deflecting light guide plate 21 at the incident end face 2 thereof.
It is incident from 1a.

The light incident on the deflection light guide plate 21 from the incident end face 21a is totally reflected at the interface between the front surface 21b of the deflection light guide plate 21 and the outside air (air) as shown by the arrow in FIG. By the reflection and the reflection at the reflection plate 23 arranged in contact with the rear surface 21c of the deflection light guide plate 21, the light is guided through the deflection light guide plate 21 and is incident on the curved reflection surfaces 22a of the plurality of bending grooves 22. The curved reflecting surface is reflected by the interface between the curved reflecting surface 22b and the outside air (air in the bending groove 22) toward the front surface 21b of the deflection light guide plate 21, and is reflected by the interface that bends in a wave shape. 22a, that is, in the width direction of the deflecting light guide plate 21, and spreads over the entire width of the deflecting light guide plate 21.
Emitted with uniform intensity from the entire area of b.

That is, in the surface light source 20, the light emitted from the solid-state light emitting element 24 and incident on the deflection light guide plate 21 from the incident end face 21a thereof is formed on the rear surface 21c of the deflection light guide plate 21. Bending reflection surface 2 of the bending groove 22
By 2a, the light is diffused in the width direction of the deflection light guide plate 21, reflected toward the front surface 21b of the deflection light guide plate 21, and the light is emitted from the entire area of the front surface 21b of the deflection light guide plate 21 with uniform intensity. Therefore, it is possible to emit light having a uniform luminance distribution with a small number of light emitting elements.

Moreover, in this embodiment, the inclination angle (angle with respect to the normal line of the front surface 21b of the turning light guide plate 21) of the bending reflection surface 22a of the plurality of bending grooves 22 of the turning light guide plate 21 is in the range of 15 to 60 degrees. Therefore, the deflection light guide plate 2
As shown in FIG. 10, the light incident on the first light-incident end face 21a and incident on the bending reflection surface 22a of the plurality of bending grooves 22 by the bending reflection surface 22a is directed to the side surface of the deflecting light guide plate 21 as shown in FIG. The front surface 2 of the turning light guide plate 21 when viewed from above
It is possible to increase the front brightness of the light emitted from the front surface 21b of the turning light guide plate 21 by refracting it toward the vicinity of the direction near the normal line of 1b.

Therefore, by disposing the surface light source 20 behind the transmissive liquid crystal display element 30 as shown in FIG. 9, the brightness of the screen is uniform and there is no brightness unevenness, and the front brightness is high. A liquid crystal display device of display quality can be obtained.

Further, since the surface light source 20 has the reflection plate 23 arranged on the rear side of the deflection light guide plate 21,
External light incident from the front side of the deflection light guide plate 21 is transmitted through the deflection light guide plate 21 in the thickness direction and is reflected by the reflection plate 23, and the reflected light is passed through the deflection light guide plate 21 again in the thickness direction. The liquid crystal display device can be transmitted and emitted to the front surface 21b thereof. Therefore, the liquid crystal display device uses reflective light that uses external light that is the light of its environment of use, and transmissive display that uses illumination light from the surface light source 20. Both the display and can be performed.

FIG. 12 is a side view of a surface light source showing a fifth embodiment of the present invention. A surface light source 20a of this embodiment has an incident end face 21a at one end and a plurality of front face 21b bent in a wave shape. Of the deflection light guide plate 21 in which the curved groove 22 is formed and the rear surface 21c is an emission surface made of a flat surface, and one solid state light emitting element 24 arranged to face the incident end surface 21a of the deflection light guide plate 21. Has become.

The deflecting light guide plate 21 has a front surface 2
Although a plurality of bending grooves 22 are formed in 1b and the rear surface 21c is used as an emission surface, the configuration is the same as that of the turning light guide plate 21 of the fourth embodiment which is turned upside down. The angle of inclination of the bent reflection surface 22a of the groove 22 (angle with respect to the normal line of the rear surface 21c of the turning light guide plate 21) is set to 15 to 6.
It is set in the range of 0 degrees.

The surface light source 20a of this embodiment is arranged in front of the reflection type liquid crystal display element (active matrix type or simple matrix type liquid crystal display element) 31 shown by a virtual line (two-dot chain line) in the figure. Light emitted from the solid-state light emitting element 24 is emitted from the rear surface 21 via the deflection light guide plate 21.

That is, the surface light source 20a emits light emitted from the solid-state light-emitting element 24 and incident on the deflection light guide plate 21 from the incident end face 21a thereof into a plurality of lights formed on the front surface 21b of the deflection light guide plate 21. The bending reflection surface 22a of the bending groove 22 diffuses in the width direction of the deflection light guide plate 21 and reflects it toward the rear surface 21c of the deflection light guide plate 21, and reflects the light from the entire rear surface 21c of the deflection light guide plate 21. Since the light is emitted with a uniform intensity, it is possible to emit light with a uniform luminance distribution with a small number of light emitting elements.

Moreover, in this embodiment, the inclination angle of the bending reflection surface 22a of the plurality of bending grooves 22 of the deflection light guide plate 21 is in the range of 15 to 6 degrees, so that the deflection light guide plate 21 is formed.
To the plurality of bent grooves 2 by being incident on the entrance end face 21a thereof.
The light incident on the second curved reflection surface 22a is reflected by the curved reflection surface 22a as shown in the figure.
When viewed from the side surface direction of the deflecting light guide plate 21, the light can be reflected toward the vicinity of the normal line of the rear surface 21c of the deflection light guide plate 21.

The light emitted to the rear surface 21c of the deflection light guide plate 21 is incident on the reflection type liquid crystal display element 31 from the front surface thereof, and the reflection film 32 on the rear side of the liquid crystal display element 31.
The light reflected by and emitted to the front surface of the liquid crystal display element 31 passes through the deflection light guide plate 21 in the thickness direction and is emitted to the front side.

By arranging the surface light source 20a on the front side of the reflective liquid crystal display element 31, a liquid crystal display device of good display quality with uniform brightness of the screen and no uneven brightness, and high front brightness can be obtained. be able to.

Further, the deflecting light guide plate 2 of the surface light source 20a.
No. 1 transmits the light incident from the front side in the thickness direction and emits it to the rear surface 21c, and transmits the light incident from the rear side in the thickness direction and emits it to the front surface 21b. In addition, it is possible to display both a reflective display using external light which is the light of the environment of use and a reflective display using the illumination light from the surface light source 20a.

In the fourth and fifth embodiments described above,
Although the plurality of bending grooves 22 of the turning light guide plate 21 are formed in a shape of bending in a sinusoidal shape, the plurality of bending grooves 22 are formed.
Is not limited to a sine wave, but may be formed into a shape that is bent into a circle, an elliptic wave, a triangular wave, or the like.

The surface light sources 20 and 20a of the fourth and fifth embodiments are provided with the incident end surface 21 of the deflecting light guide plate 21.
Although one solid-state light-emitting element 24 is arranged so as to face a, the number of the solid-state light-emitting element 24 is not limited to one, and a plurality of solid-state light-emitting elements may be used as the incident end surface 2 of the deflection light guide plate 21.
1a may be arranged side by side at an appropriate interval in the length direction of 1a, and in that case, as in the second embodiment described above, a solid-state light-emitting element that emits red light and a solid-state light-emitting element that emits green light. And a solid-state light emitting element that emits blue light may be arranged side by side.

Further, the surface light sources 10, 10a and 10b of the first to third embodiments are provided with the prism sheet 11 having a plurality of bent prism portions 12 formed on one surface as a light redirecting member. The surface light sources 20 and 20a of the fourth and fifth embodiments are provided with the deflection light guide plate 21 having a plurality of bent grooves 22 formed on one surface as a light deflection member. The light diverting member is not limited to the prism sheet 11 or the diverting light guide plate 21, and a plurality of bending reflecting surfaces or bending bending surfaces that are bent in a wave shape along one direction are formed on one of the front and rear surfaces. , Refracting or reflecting light incident on the plurality of bending reflection surfaces or bending refraction surfaces from a direction intersecting the one direction toward the other surface from these bending reflection surfaces or bending refraction surfaces, and Because it goes out from the other side, It may be Re, also solid state light emitters also
The LED is not limited to the LED, and may be an EL (electroluminescence) or the like.

Further, the surface light source of the present invention is not limited to the illumination light source of the liquid crystal display device and can be widely used for other purposes.

[0083]

According to the surface light source of the present invention, a plurality of bending reflection surfaces or bending refraction surfaces that are bent in a wave shape along one direction are formed on one of the front and back surfaces and intersect the one direction. Light that is incident on one of the plurality of bending reflection surfaces or bending refraction surfaces from one direction is refracted or reflected from the bending reflection surface or bending refraction surface toward the other surface, and the light is redirected from the other surface. A light emitting member, and at least one solid-state light emitting element that is disposed on one end side of the light diverting member in a direction intersecting the one direction and emits light toward the light diverting member. Light with uniform brightness can be emitted with a small number of light emitting elements.

In the surface light source of the present invention, the light diverting member has, for example, a plurality of bending prism portions that are bent in a wave shape along one direction on one of the front and rear surfaces. One side surface of the both side surfaces facing the arrangement side of the solid state light emitting element is a bent incident surface on which the light emitted from the solid state light emitting element is incident, and the other side surface is the light incident from the bent incident surface. Is preferably a prism sheet having a bending refraction surface that is refracted toward the other surface, and in that case, the solid-state light-emitting element emits light in a direction along a surface on which the bending prism portion of the prism sheet is formed. By arranging so as to emit light, it is possible to emit light of uniform brightness with a small number of light emitting elements.

When the prism sheet is used as the light diverting member in this manner, the surface of the prism sheet on which the bent prism portion is formed has an incident end face at one end and guides the light incident from the incident end face. It is more preferable to dispose a light guide plate that emits light from a surface facing the prism sheet, and to dispose the solid-state light-emitting element so as to face an incident end surface of the light guide plate. Light emitted from the element can be efficiently incident on the plurality of bent prism portions of the prism sheet, and high-luminance light can be emitted from the front surface of the prism sheet.

Further, the light diverting member has an incident end face at one end, and a plurality of bending grooves bent in a wave shape along one direction are formed on one of the front and rear surfaces. Of both side surfaces, one side surface facing the incident end surface side may be a deflecting light guide plate that is a bending reflection surface that reflects light incident from the incident end surface toward the other surface, and in that case,
By disposing the solid-state light emitting element so as to face the incident end surface of the deflection light guide plate, it is possible to emit light with uniform brightness with a small number of light emitting elements.

[Brief description of drawings]

FIG. 1 is a perspective view of a surface light source showing a first embodiment of the present invention.

FIG. 2 is a side view of the surface light source.

FIG. 3 is a bottom view of a prism sheet provided as a light diverting member of the surface light source.

FIG. 4 is a schematic diagram showing diffusion of light by the prism sheet.

FIG. 5 is a perspective view of a surface light source showing a second embodiment of the present invention.

FIG. 6 is a schematic diagram showing light diffusion by a prism sheet of the surface light source of the second embodiment.

FIG. 7 is a perspective view of a surface light source showing a third embodiment of the present invention.

FIG. 8 is a side view of a surface light source according to a third embodiment.

FIG. 9 is a perspective view of a surface light source showing a fourth embodiment of the present invention.

FIG. 10 is a side view of a surface light source according to a fourth embodiment.

FIG. 11 is a bottom view of a turning light guide plate provided as a light turning member of the surface light source of the fourth embodiment.

FIG. 12 is a side view of a surface light source showing a fifth embodiment of the present invention.

FIG. 13 is a perspective view of a conventional surface light source including a solid-state light emitting element.

[Explanation of symbols]

10, 10a, 10b, 20, 20a ... Surface light source 11 ... Prism sheet 12 ... Bending prism part 12a ... Bent incident surface, 12b ... Bending and refracting surface 13 ... Reflector 14, 14R, 14G, 14B ... Solid state light emitting device 15 ... Light guide plate 15a ... Incident end face 21 ... Diversion light guide plate 22 ... Bending groove 22a ... Bending reflection surface 23 ... Reflector 24 ... Solid-state light-emitting element 30 ... Transmissive liquid crystal display element 31 ... Reflective liquid crystal display element

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) G09F 9/00 324 G09F 9/00 324 336 336C 336J 9/35 9/35 // F21Y 101: 02 F21Y 101: 02 F Terms (reference) 2H042 BA04 BA14 BA20 2H091 FA21Z FA23Z FA45Z FD06 FD07 LA18 5C094 AA03 AA55 BA43 ED01 FA04 5G435 AA01 BB12 BB15 EE23 EE27 FF02 FF08 FF12 GG03 GG23

Claims (4)

[Claims] 1. A plurality of bending reflection surfaces or bending refraction surfaces that are bent in a wave shape along one direction are formed on one of the front and rear surfaces, and the plurality of bending reflection surfaces are formed in a direction intersecting the one direction. A light diverting member that refracts or reflects light incident on a surface or a bending and refracting surface toward the other surface from the bending reflecting surface or the bending and refracting surface, and emits the light from the other surface, and the light diverting member. A surface light source, comprising: at least one solid-state light-emitting element, which is disposed on one end side of the member in a direction intersecting the one direction and emits light toward the light diverting member. 2. The light diverting member has a plurality of bent prism portions that are bent in a wave shape along one direction on one of the front and rear surfaces, and solid-state light emission is performed on both side surfaces of these bent prism portions. One side surface facing the arrangement side of the element is a bent incident surface on which the light emitted from the solid-state light emitting element is made incident, and the other side surface refracts the light incident from the bent incident surface toward the other surface. And a solid-state light emitting element, wherein the solid-state light-emitting element is arranged so as to emit light in a direction along a surface of the prism sheet on which the bent prism portion is formed. The surface light source according to claim 1. 3. A light guide plate having an incident end face at one end on a surface of the prism sheet on which the bent prism portion is formed, and a light guide plate which guides light incident from the incident end face and emits the light from a surface facing the prism sheet. The surface light source according to claim 2, wherein the solid-state light emitting element is arranged so as to face the incident end surface of the light guide plate. 4. The light diverting member has an incident end face at one end, and a plurality of bending grooves bent in a wave shape along one direction are formed on one of the front and rear surfaces, and both sides of these bending grooves are formed. Out of the plane
One side surface facing the incident end face side is a deflecting light guide plate that is a bent reflecting surface that reflects light incident from the incident end face toward the other surface, and the solid state light emitting element is a deflecting light guide plate of the deflecting light guide plate. The surface light source according to claim 1, wherein the surface light source is arranged so as to face the incident end surface.