KR101509372B1 - Surface light source device and liquid crystal display device - Google Patents

Abstract

The planar light source device 100 includes a planar light-emitting planar light-guide plate 15 having a front surface 15a, a rear surface 15b and a light incidence surface 15c, and a first light source 101 for emitting a first light L12 Emitting light guiding plate 15 has an angular intensity distribution regulating region 15e as a first region that widens the angular intensity distribution of the first light beam while propagating the first light ray incident from the light incident surface 15c, And a second region 15f for emitting a first light beam L12 having an expanded angular intensity distribution from the surface 15a as light having a planar shape.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a surface light source device and a liquid crystal display device,

The present invention relates to a planar light source device having a planar light emitting surface, and a liquid crystal display device having the planar light source device and the liquid crystal panel.

BACKGROUND ART [0002] Recently, as a backlight unit of a liquid crystal display device, light from a light source is incident on a side (light incident surface) of a thin plate-like surface light-emitting light guide plate and diffused light is emitted from a front surface A side light type surface light source device that emits toward the entire back surface of a liquid crystal display element (liquid crystal panel) is widely used. However, since it is difficult to provide a large number of light sources (for example, LEDs) of a large light amount in opposition to a narrow surface called a side surface of a thin plate-like surface light-emitting light guide plate, in the side light type surface light source device, There is a problem that it is difficult to improve the performance.

As a countermeasure to this problem, a plurality of light sources (a plurality of light emitting element rows) arranged in the thickness direction of the surface light source device, a surface light emitting light guide plate, and light from a plurality of light sources, There is a proposal of a surface light source device having an optical path changing member (for example, a light reflecting mirror or the like) for guiding light from the light source (for example, see Patent Document 1).

Patent Document 1: Japanese Patent Application Laid-Open No. 2005-250020 (paragraphs 0010 to 0023, Figs. 1 to 8) However, in the liquid crystal display device, it is preferable to employ a laser light emitting element as the light source for the purpose of improving the image quality by broadening the color reproduction range. Since a laser light emitting element emits highly pure light, it is possible to provide a clear image having a wide color reproduction range in a liquid crystal display device using a laser light emitting element as a light source.

On the other hand, the light emitted from the laser emitting element has a high directivity. Therefore, when the side light type surface light source device employs the laser light emitting element, the ratio of the amount of light emitted from the surface light-emitting light guide plate toward the liquid crystal panel to the amount of light incident to the surface light- Is lowered.

Further, in the case of generating surface light using a common surface emitting light guide plate using both a light source made of a laser emitting element and a light source having an angular intensity distribution different from the angular intensity distribution of the light emitted from the laser emitting element There is a problem that the difference in the angular intensity distribution causes color unevenness in the surface. In general, a light source employed as a light source of a liquid crystal display device has many angular intensity distributions. For example, the angular intensity distribution of the light emitted from the LED is approximately a Lambertian distribution and is very broad compared to the angular intensity distribution of the light emitted from the laser emitting element.

It is therefore an object of the present invention to provide a surface light source device and a liquid crystal display device capable of suppressing the use efficiency of light and color unevenness even when a light source having high directivity is employed as the light source, And to provide a device.

A surface light source device according to the present invention is a surface light source device having a first surface, a second surface opposite to the first surface, and a third surface connecting a side of the first surface and a side of the second surface And a second light source for emitting a second light ray incident on the third surface of the surface light-emitting light guide plate, wherein the second light source emits the second light ray from the second light source, The angular intensity distribution of the second light beam immediately after the first light source is larger than the angular intensity distribution of the first light ray immediately after the first light source is emitted from the first light source, A first region for propagating the incident first and second light beams and widening an angular intensity distribution of the first light beam while propagating the first and second light beams, Face And it is characterized in that it has a second region for emitting a light on.

A liquid crystal display device according to the present invention is characterized by including a liquid crystal panel and the above-mentioned surface light source device for irradiating the back surface of the liquid crystal panel with surface light.

The surface light source device and the liquid crystal display device according to the present invention can provide a surface light source device and a liquid crystal display device capable of suppressing the use efficiency of light and color unevenness even when a light source having high directivity is employed as the light source.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a cross-sectional view schematically showing an exemplary configuration of a liquid crystal display device (including a surface light source device) according to Embodiment 1;
2 is a perspective view schematically showing a configuration of an optical path changing member of the surface light source device according to the first embodiment.
3 is a schematic plan view of the surface light source device according to the first embodiment as viewed from the liquid crystal panel side.
4 is a schematic rear view of the surface light source device according to the first embodiment as viewed from the rear side of the liquid crystal display device.
5 is a schematic rear view showing another example of the surface emitting light guide plate of the surface light source device according to the first embodiment.
6 is a schematic explanatory diagram showing the behavior of the first light ray in the surface light-emitting light guide plate according to the first embodiment.
7 is a characteristic diagram showing the angular intensity distribution in the surface light-emitting light guide plate of the first light ray according to the first embodiment.
8 is a characteristic diagram showing the angular intensity distribution in the surface-emitting light guide plate of the first light beam and the second light ray according to Embodiment 1. Fig.
Fig. 9 is a block diagram schematically showing a configuration of a control system of a liquid crystal display device according to Embodiment 1. Fig.
10 is a cross-sectional view schematically showing an exemplary configuration of a liquid crystal display device (including a surface light source device) according to the second embodiment.
11 is a cross-sectional view schematically showing the configuration of another example of a liquid crystal display device (including a surface light source device) according to the second embodiment.
12 is a cross-sectional view schematically showing an exemplary configuration of a liquid crystal display device (including a surface light source device) according to the third embodiment.
13 is a cross-sectional view schematically showing the configuration of another example of a liquid crystal display device (including a surface light source device) according to the third embodiment.
14 is a cross-sectional view schematically showing another example of the configuration of a liquid crystal display device (including a surface light source device) according to the third embodiment.

(Embodiment 1)

1 is a cross-sectional view schematically showing an example of the configuration of a liquid crystal display 1 (including a surface light source device 100) according to the first embodiment. 2 is a perspective view schematically showing a configuration of a cylindrical mirror 102 as a light reflecting member of the surface light source device 100 shown in Fig. Fig. 3 is a schematic plan view of the surface light source device 100 shown in Fig. 1 viewed from the liquid crystal panel 11 side, Fig. 4 is a plan view showing the surface light source device 100 shown in Fig. 1 on the back surface side of the liquid crystal display device 1 As shown in Fig.

The liquid crystal display device 1 is a transmissive liquid crystal display device 1 having a liquid crystal display element (hereinafter also referred to as a " liquid crystal panel ") 11 having a rectangular display surface 11a and a reverse surface 11b on the opposite side thereof, to be. For ease of explanation, the coordinate axes of the xyz orthogonal coordinate system are shown in the respective figures. In the following description, the short side direction of the display surface 11a of the liquid crystal panel 11 is set to the y axis direction (the direction perpendicular to the paper plane shown in Fig. 1) (The left-right direction in FIG. 1), and the direction perpendicular to the xy plane is the z-axis direction (the up-down direction in FIG. 1). 1, the direction from the left to the right is defined as the normal direction of the x-axis (+ x-axis direction), and the opposite direction is defined as the x-axis negative direction (-x-axis direction). In addition, the direction from the front of the sheet of Fig. 1 to the sheet is the forward direction of the y-axis (+ y-axis direction) and the reverse direction is the y-axis negative direction (-y-axis direction). 1, the direction from the bottom to the top is the positive direction of the z axis (+ z axis direction), and the opposite direction is the negative direction of the z axis (-z axis direction).

1, the liquid crystal display device 1 according to the first embodiment has a transmissive liquid crystal panel 11, a first optical sheet 12, a second optical sheet 13, and a backlight unit 100 have. The backlight unit 100 is a surface light source device that emits light to the back surface 11b of the liquid crystal panel 11 through the second optical sheet 13 and the first optical sheet 12. [ These components 11, 12, 13, and 100 are arranged in order along the -z axis.

The display surface 11a of the liquid crystal panel 11 is a surface parallel to the xy plane. The liquid crystal layer of the liquid crystal panel 11 has a planar structure spreading in a direction parallel to the xy plane. The display surface 11a of the liquid crystal panel 11 is generally rectangular and two adjacent sides of the display surface 11a are perpendicular to each other in the y-axis direction and the x-axis direction in Embodiment 1 . However, the shape of the display surface 11a may be different.

1, the planar light source device 100 includes a planar light-emitting planar light-guide plate 15, a light-reflecting sheet 17, a second light source 18, a first light source 101, and a cylindrical mirror 102 ). The cylindrical mirror 102 has a function as an optical path changing member. Here, the second light source 18 and the first light source 101 are arranged such that the angular intensity distribution of the second light ray immediately after the second light ray is emitted from the second light source 18 is changed from the first light source 101 to the first Is selected to be wider than the angular intensity distribution of the first ray immediately after the ray is emitted.

The light emitting portion for emitting the second light ray L11 of the second light source 18 is disposed opposite to the light incident surface (side surface) 15c of the surface light-emitting light guide plate 15. [ The second light source 18 is a light source device in which one or more, preferably, a plurality of light emitting diode (LED) elements are arranged at regular intervals in the y-axis direction. The second light source 18 is disposed within the range of the length of the light incident surface 15c (third surface) in the z-axis direction. That is, it is preferable that the second light source 18 is disposed within the thickness range of the surface light-emitting light guide plate 15. 1 shows a case in which the second light beam L11 emitted from the second light source 18 is incident on the light incident surface 15c of the direct surface light-emission light guide plate 15. [ However, the second light beam L11 may be incident on the light incident surface 15c through another optical element such as a lens. In addition, the outgoing light means emitting light in an arbitrary direction.

The first light source 101 is disposed on the back surface 15b side (-z axis direction) opposite to the surface 15a of the surface light-emitting light guide plate 15. The first light source 101 is a light source device in which one or more, preferably, a plurality of laser light emitting elements are arranged at regular intervals in the y-axis direction. The light emitting portion for emitting the first light beam L12 of the first light source 101 is arranged to face the light reflecting surface 102a of the cylindrical mirror 102. [

The light reflecting surface 102a of the cylindrical mirror 102 is arranged so as to face the light incident surface 15c of the surface light- As shown in Figs. 1 and 2, the sectional shape when the light reflecting surface 102a is cut in the xz plane is a concave circular arc shape toward the light incident surface 15c side. In addition, the sectional shape when the light reflecting surface 102a is cut in the xy plane is a linear shape extending in the y-axis direction. The light reflecting surface 102a is a light reflecting surface of the cylindrical mirror 102. [ The light incident surface 15c is an end surface of the surface light-emitting light guide plate 15. Further, the cylindrical mirror 102 is the first light reflection member.

In the example shown in Figs. 1 and 2, the cylindrical mirror 102 in the first embodiment is in the shape of a quarter cylinder of an ellipse having an eccentricity of 0.47. The major axis of the ellipse is parallel to the x-axis. In addition, the cylindrical mirror 102 has its concave surface side as the light reflecting surface 102a. The light reflecting surface 102a may have a cylindrical or nylon cylindrical shape (n is a number greater than 1) obtained by dividing the cylindrical or the cylindrical shape into n pieces in a plane passing through the axis (axis parallel to the y-axis) .

On the light reflecting surface 102a of the cylindrical mirror 102, for example, a layer of a metal film for reflecting light is provided. The direction of the tangent of the light reflecting surface 102a differs depending on each position. Therefore, when the light flux (light flux having a bundle of light rays and having a size) is incident on the light reflection surface 102a, each light ray is reflected at a different exit angle depending on the incident position.

The base of the cylindrical mirror 102 is an acrylic resin (for example, PMMA). The light reflecting surface 102a is, for example, a surface on which aluminum is vapor-deposited. However, the material and shape of the cylindrical mirror 102 are not limited to this example. For example, other resins or metals having excellent processability may be employed for the substrate. In addition, another metal having a high reflectance such as silver or gold may be used for the metal film deposited on the light reflecting surface 102a.

The surface light-emitting light guide plate 15 is a plate-like optical member having a surface (first surface) 15a, a back surface 15b (second surface), and a plurality of side surfaces (third surface). The back surface 15b is a surface facing the surface 15a. The plurality of side surfaces are elongated surfaces connecting the sides (end portions) of the surface 15a and the sides (end portions) of the back surface 15b. The planar light-emitting light guide plate 15 is a light-transmitting optical member. Further, the surface light-emitting light guide plate 15 has a plurality of micro-optical elements 16 on the back surface 15b. As shown in Fig. 1, in Embodiment 1, the surface 15a and the back surface 15b are substantially parallel. Further, the surfaces of the surface 15a and the back surface 15b are parallel to the xy plane. Hereinafter, a plane parallel to the surface 15a and the back face 15b is referred to as a reference plane of the planar light-guide light guide plate 15. [

The planar light-emitting light guide plate 15 and the micro-optical element 16 constitute the optical member 14. The micro-optical element 16 has a function of directing the light ray incident from the light incident surface 15c of the surface light-emitting light guide plate 15 toward the surface 15a side. The amount of the illumination light L14 directed to the surface 15a increases in a region occupied by the micro optical element 16. The area occupied by the micro-optical element 16 is a region having a large area (in the case of FIG. 4 described later) and an arrangement density of the micro-optical elements 16 (In the case of FIG. 5 to be described later). Therefore, the number of the micro-optical elements 16 per unit area (the number of micro-optical elements 16) is increased so that the area occupied by the micro-optical elements 16 increases as the distance from the light incident surface 15c of the surface- And the shape of the substrate.

The number of micro-optical elements 16 shown in Figs. 1 and 4 in the shape and arrangement positions is an example. The micro-optical element 16 shown in Figs. 1 and 4 has a configuration in which the shape of the micro-optical element 16 is increased as it is further away from the light incident surface 15c in the + x direction so that the area occupied by the micro- . The micro-optical element 16 shown in Fig. 5 has the same size as the micro-optical element 16 and has an arrangement density of the micro-optical elements 16 (unit area per side) as the distance from the light incident surface 15c in the + The number of users is increased. As described above, the area occupied by the micro-optical element 16 can be changed depending on the number and shape per unit area of the micro-optical element 16. [

The surface 15a of the planar light-emitting light guide plate 15 is arranged parallel to the display surface 11a of the liquid crystal panel 11. [ The surface light-emitting guiding plate 15 has an angular intensity distribution shaping area 15e (first area) having a predetermined length from the light incidence surface 15c to the center of the surface light-emitting shading plate 15. For example, the angular intensity distribution shaping area 15e is an area of 20 mm from the light incident surface 15c in the + x axis direction. In the angular intensity distribution shaping area 15e, the surface-emitting light guide plate 15 does not have the same optical structure as the micro-optical elements 16 on both the surface 15a and the back surface 15b, but is in contact with the air layer. Light incident from the light incident surface 15c into the angular intensity distribution shaping region 15e propagates (propagates) in the + x axis direction while being totally reflected at the interface with the air layer. The air layer is air surrounding the optical member. The interface with the air layer is a surface 15a and a back surface 15b which are in contact with the air layer. The angular intensity distribution shaping area 15e of the planar light-guiding light guide plate 15 is an area that widens the angular intensity distribution of the first light beam while propagating the first light beam incident from the light incident surface 15c. The planar light-emitting light guide plate 15 is configured to have an angular intensity distribution of the first light ray immediately after passing through the angular intensity distribution shaping area 15e of the planar light-incidence light guide plate 15 and an angular intensity distribution of the first light ray immediately after passing through the angular intensity distribution shaping area 15e It is preferable that the angular intensity distribution of the second light ray in the second lens group is substantially equal.

The surface emitting light guide plate 15 has a micro optical element 16 on the back surface 15b of the area 15f (second area). The region 15f is a region adjacent to the + x-axis direction of the angular intensity distribution shaping region 15e. Therefore, the angular intensity distribution shaping area 15e is disposed between the light incident surface 15c and the area 15f. The back surface 15b is a surface on the opposite side to the liquid crystal panel 11. The micro-optical element 16 has a function of converting the mixed light beam L13 into the illumination light L14. The mixed light ray L13 is a light ray mixed with the second light ray L11 and the first light ray L12 propagating inside the surface light-emitting light guide plate 15. [ The illumination light L14 is light that is emitted toward the + z-axis direction. The illumination light L14 is emitted from the surface-emitting light guide plate 15 toward the back surface 11b of the liquid crystal panel 11. [

The surface light-emitting light guide plate 15 is a part made of a transparent material. For example, it is a thin plate-shaped member having a thickness of 4 mm in the z-axis direction. As shown in Fig. 4, a plurality of micro-optical elements 16 are provided on the back surface 15b of the surface light- The micro optical element 16 is a semi-spherical convex lens-shaped element protruding in the -z axis direction.

The material of the surface light-emitting light guide plate 15 and the micro-optical element 16 may be acrylic resin such as PMMA, for example. However, the material of the surface light-emitting light guide plate 15 and the micro-optical element 16 is not limited to acrylic resin. As the material of the planar light-emitting light guide plate 15 and the micro-optical element 16, a material having good light transmittance and excellent moldability can be employed. For example, other resin materials such as a polycarbonate resin can be employed in place of the acrylic resin. Alternatively, a glass material can be used for the material of the surface light-emitting light guide plate 15 and the micro-optical element 16. [ In addition, the thickness of the surface light-emitting light guide plate 15 is not limited to 4 mm, and it is preferable to employ a planar light-emitting light guide plate 15 having a small thickness in consideration of the thickness and weight reduction of the liquid crystal display device 1.

The shape of the micro-optical element 16 is not limited to the convex lens shape. The micro-optical element 16 reflects the mixed light beam L13 in the + z-axis direction and the mixed light beam L13 passes through the back surface of the liquid crystal panel 11 And the light is emitted toward the light emitting element 11b. The mixed light ray L13 is light propagating in the + x-axis direction inside the surface light-emitting light guide plate 15. If this function is provided, the micro-optical element 16 may have a different shape. For example, the micro optical element 16 may be a prism shape or a random irregular pattern.

The mixed light ray L13 is totally reflected at the interface between the surface light-emitting light guide plate 15 and the air layer. Then, the mixed light L13 propagates inside the surface light-emitting light guide plate 15. The mixed ray L13 proceeds in the + x axis direction while reflecting. However, when the mixed light beam L13 is incident on the micro-optical element 16, it is reflected by the curved surface of the micro-optical element 16 to change its traveling direction. When the traveling direction of the mixed light beam L13 changes, a ray of light that does not satisfy the total reflection condition at the interface between the surface of the surface light-emitting light guide plate 15 and the air layer occurs in the mixed light ray L13. When the light ray does not satisfy the total reflection condition, the light ray is emitted from the light emitting surface 15a of the planar light-guide light guide plate 15 toward the back surface 11b of the liquid crystal panel 11.

The arrangement density of the minute optical elements 16 changes at a position in the xy plane on the planar light-guide light guide plate 15. The batch density is the number of micro-optical elements 16 per unit area or the area (size) occupied by the micro-optical elements 16 per unit area. The in-plane luminance distribution of the illumination light L14 can be controlled by the change in the arrangement density of the minute optical elements 16. [ The illumination light L14 is light emitted from the planar light-guide light-guide plate 15. In addition, the in-plane luminance distribution is a distribution showing the brightness of the luminance with respect to the position expressed in two dimensions in an arbitrary plane. Here, the surface interference is the surface 15a or the display surface 11a.

The second light beam L11 is incident on the light incident surface 15c of the planar light-emitting light guide plate 15 from the second light source 18 and the first light beam L12 is incident on the first light source 101. [ The axis of the second light beam L11 (that is, the central axis of the second light beam L11) is directed from the second light source 18 toward the light incident surface 15c in the + x axis direction (the right direction in Fig. 1). At this time, the axis of the light ray (for example, the "axis of the second light ray L11") is parallel to the reference plane (the xy plane in FIG. 1) of the surface light- Here, the axis of the second light ray L11 refers to an axis in the angular direction which becomes a weighted average of the angular intensity distribution in an arbitrary plane of the light ray. The weighted average angle is obtained by weighting the light intensity at each angle and averaging. When the peak position of the light intensity deviates from the center of the angular intensity distribution, the axis of the light ray does not become the angle of the peak position of the light intensity. The axis of the ray is the angle of the center position of the area of the angular intensity distribution.

The axis of the first light beam L12 is directed from the first light source 101 in the + z-axis direction (upward in Fig. 1). The first ray L12 has an angular intensity distribution narrower than the second ray L11. The axis of the first ray L12 is transformed by the cylindrical mirror 102 approximately in the + x axis direction, and is directed to the light incident surface 15c. The cylindrical mirror 102 has a function as an optical path changing member.

The cylindrical mirror 102 has the following two functions. The first function is a function of tilting the axis of the first light ray L12 at an arbitrary angle with respect to the reference plane of the surface light-emission light guide plate 15. [ The reference plane is the xy plane of Fig. The second function is to change the progressive direction and the angular intensity distribution of the first ray L12 such that the angular intensity distribution of the first ray L12 is arbitrary in the plane parallel to the zx plane. The zx plane is a plane orthogonal to the reference plane of the planar light-emitting light guide plate 15. Hereinafter, a plane parallel to the zx plane is referred to as a plane in the thickness direction of the planar light-emitting light guide plate 15. [

The surface light source device 100 according to the first embodiment uses an LED element as the second light source 18. LED devices generally have a wide angle intensity distribution. The second light beam L11 emitted from the second light source 18 is incident on the surface light emission surface of the planar light guide plate 15 in the thickness direction (zx plane in Fig. 1) with an angular intensity distribution of a substantially Lambertian distribution having an overall angle I have. The second light beam L11 is incident on the surface-emitting light guide plate 15 from the incident surface 15c without changing the angular intensity distribution.

On the other hand, the surface light source device 100 according to the first embodiment uses a laser light emitting element as the first light source 101. Laser light emitting devices generally have a narrow angular intensity distribution. The first light ray L12 emitted from the first light source 101 has an angular intensity distribution of an approximately Gaussian distribution in which the full angle is 7 degrees in the plane in the thickness direction of the planar light-emitting light guide plate 15 (zx plane in Fig. The first light ray L12 passes through the cylindrical mirror 102 to expand the full angle in the plane in the thickness direction (zx plane in Fig. 1) of the surface light-emitting light guide plate 15. [ Therefore, the cylindrical mirror 102 also has the function of the angular intensity distribution as a shaping member. Here, the full angle of the angular intensity distribution refers to an angle (full angle) in a direction in which the light intensity becomes 50% of the maximum intensity.

As shown in Fig. 1, in the surface light source device 100 of the first embodiment, the first light source 101 is arranged so that the first light ray L12 is inclined with respect to the z-axis. The light reflecting surface 102a of the cylindrical mirror 102 is arranged inclined with respect to the light incident surface 15c of the surface emitting light guide plate 15 in the y-axis direction. The reason why the first light source 101 and the light reflecting surface 102a are arranged in this manner is as follows. The first reason is that the light beam L12 is incident on the cylindrical mirror 102 efficiently. The second reason is that the first light ray L12 enters the light-emitting light guide plate 15 efficiently. The third reason is that the axis of the first ray L12 has an arbitrary angle with respect to the reference plane of the surface-emitting light guide plate 15, and the first ray L12 has an arbitrary angular intensity distribution.

The positional relationship and arrangement angle between the first light source 101 and the light reflecting surface 102a are determined by the angular intensity distribution of the first light ray L12, the size (diameter) of the first light ray L12, the curvature of the cylindrical mirror 102, The thickness of the substrate 15, and the like. The positional relationship and arrangement angle between the cylindrical mirror 102 and the surface emitting light guide plate 15 are determined by the angular intensity distribution of the first ray L12, the size (diameter) of the first ray L12, the curvature of the cylindrical mirror 102, The thickness of the light guide plate 15, and the like. Therefore, when the respective conditions are different, it is necessary to optimize the positional relationship and arrangement angle of each member.

6 is a schematic diagram for explaining the behavior of the first light beam L12 in the angular intensity distribution shaping region 15e. In order to clarify the behavior of the first light beam L12, the second light beam L11 emitted from the second light source 18 is omitted in Fig.

The axis of the first light ray L12 has an inclination at an arbitrary angle with respect to the reference plane of the surface light-emitting light guide plate 15. [ Therefore, the first light beam L12 has a slope and is incident on the angular intensity distribution shaping region 15e. Thus, the first light beam L12 incident on the planar light-guide light guide plate 15 propagates in the + x-axis direction while repeating reflection on the surface 15a and the back face 15b of the angular intensity distribution shaping area 15e. At this time, the first ray L12 propagates while diverging due to its divergence angle. Therefore, the first light ray L12 is bent at the surface 15a and the back face 15b of the surface light-emitting light guide plate 15 at the plane in the thickness direction (zx plane in Fig. 6) Is superimposed on the light diameter equal in size to the thickness of the light guide plate (15). Thus, the angular intensity distribution of the first ray L12 emitted from the angular intensity distribution shaping region 15e to the region 15f is the angular intensity distribution of the first ray L12 when it is incident on the angular intensity distribution shaping region 15e And the angular intensity distribution bent symmetrically with respect to the reference plane of the planar light-emitting light guide plate 15 are added to each other.

Figs. 7 and 8 are diagrams showing changes in the angular intensity distribution of the first ray L12 in the first embodiment. Fig. 7 and 8, the ordinate axis represents the light intensity (arbitrary unit (au)) and the abscissa axis represents the angle (degree). Incidentally, 0 degree in the horizontal axis direction indicating the angle is set in a direction parallel to the reference plane of the surface light-emission light guide plate 15.

When emitted from the first light source 101, the full angle of the angular intensity distribution of the first light ray L12 is 7 degrees. The first ray L12 is reflected by the cylindrical mirror 102. [ Thus, the axis of the first light ray L12 has a slope with respect to the reference plane of the surface light-emitting light guide plate 15. [ Further, the first light beam L12 is incident on the planar light-guide light-guide plate 15 after widening the angular intensity distribution by the cylindrical mirror 102. [

The angular intensity distribution 500a (thin line) in Fig. 7 represents the angular intensity distribution of the first ray L12 immediately after entering the angular intensity distribution shaping region 15e. 7, the first light ray L12 incident on the angular intensity distribution shaping region 15e is incident on the surface of the surface light-emission light guide plate 15 at an angle of 11 degrees from the reference plane of the surface- And has an angular intensity distribution with an overall angle of about 45 degrees. Here, the axis of the ray indicates an axis in the angular direction which is a weighted average of the angular intensity distribution in an arbitrary plane. The full angle refers to an angle (full angle) at an intensity of 50% of the highest intensity.

The first light ray L12 is refracted by the reflection and propagates through the angular intensity distribution shaping region 15e to be bent at the front face 15a and the rear face 15b of the plane light emission light guide plate 15, And is superimposed on an optical diameter of an equivalent size. Thereby, the angular intensity distribution of the first ray L12 emerging from the angular intensity distribution distribution shaping region 15e is obtained by adding the angular intensity distribution 500a (thin line) and the angular intensity distribution 500b (broken line) (510) < / RTI > Here, the angular intensity distribution 500b (broken line) is a distribution in which (500a) (thin line) is folded symmetrically with respect to the reference plane of the planar light-

8 is a diagram comparing the angular intensity distribution of the light of the LED element incident on the region 15f of the surface light-emitting light guide plate 15 with the laser light emitting element light. The second light beam L11 having an angular intensity distribution of a Lambert distribution of about 120 degrees from the second light source 18 is incident on the surface light-emission light guide plate 15 without changing the angular intensity distribution. Since the second light beam L11 is refracted at the light incidence plane 15c of the planar light guide plate 15, the angular intensity distribution of the second light beam L11 incident on the planar light- ) (White circle mark " OMARK "), the full angle is about 80 degrees.

On the other hand, the first light ray L12 emitted from the first light source 101 has a narrow angle intensity distribution as compared with the second light ray L11. The full angle of the angular intensity distribution of the first light beam L12 emitted from the first light source 101 is approximately 7 degrees. When the first light beam L12 is incident on the surface light-emitting light guide plate 15 like the second light beam L11, the angular intensity distribution of the first light beam L12 incident on the surface light- 50) (black square mark " ■ mark ").

Thus, the difference in angular intensity distribution between the second light ray L11 and the first light ray L12 is large. However, in the surface light source device 100 according to the first embodiment, the first light beam L12 passes through the cylindrical mirror 102 and the angular intensity distribution shaping area 15e, And is shaped into a shape represented by the distribution 510 (black triangle mark). Thereby, the angular intensity distribution 510 of the first ray L12 becomes substantially equal to the angular intensity distribution 520 of the second ray L11.

The second light ray L11 is, for example, a cyan light ray. The first light beam L12 is, for example, a red light beam. Both the second light ray L11 and the first light ray L12 are incident on the surface-emitting light guide plate 15 from the light incident surface 15c of the surface-emitting light guide plate 15. The angular intensity distribution shaping area 15e is disposed in the vicinity of the light incident surface 15c of the planar light-guiding light guide plate 15. The angular intensity distribution shaping area 15e also has a function of mixing the second light beam L11 and the first light beam L12. The second light beam L11 and the first light beam L12 are mixed by propagating through the angular intensity distribution shaping region 15e to become a mixed light beam (for example, a white light beam) L13.

The mixed light L13 is converted into the illumination light L14 by the micro-optical element 16 provided on the back surface 15b of the surface light- The illumination light L14 travels in the + z-axis direction and advances toward the back surface 11b of the liquid crystal panel 11. [ The illumination light L14 transmits the second optical sheet 13 and the first optical sheet 12 to irradiate the back surface 11b of the liquid crystal panel 11. The first optical sheet 12 has a function of directing the illumination light L14 emitted from the surface 15a of the surface light-emitting light guide plate 15 toward the back surface 11b of the liquid crystal panel 11. [ The second optical sheet 13 has a function of suppressing optical influence such as minute illumination unevenness by the illumination light L14.

The micro optical element 16 is arranged in the area 15f of the back surface 15b of the surface light-emitting light guide plate 15. [ The region 15f is a region extending from the light incident surface 15c by a certain length to the side surface 15d. The arbitrary length is the length of the angular intensity distribution shaping area 15e. The area of the area 15f in which the micro-optical elements 16 are arranged is substantially equal to the area of the effective image display area of the liquid crystal panel 11. [ However, it is preferable that it is slightly larger than the area of the effective image display area of the liquid crystal panel 11. [ It is preferable that the center position of the region 15f is the same as the center position of the effective image display region (region parallel to the xy plane) of the liquid crystal panel 11. [ The center position of the region 15f may be located in the vicinity of the center position of the effective image display region of the liquid crystal panel 11. [

With this configuration, the illumination light L14 emitted from the surface 15a of the planar light-guide light guide plate 15 illuminates the entire effective image display area of the liquid crystal panel 11. [ Therefore, the peripheral portion of the display surface 11a of the liquid crystal panel 11 can be prevented from becoming dark.

The surface light source device 100 has a light reflecting sheet 17. The light reflection sheet 17 is opposed to the back surface 15b of the surface light-emission light guide plate 15. [ The light emitted from the back face 15b of the planar light-emitting light guide plate 15 is reflected by the light reflection sheet 17 and is incident on the planar light-guide plate 15 from the back face 15b, (15a), and illuminates the back surface (11b) of the liquid crystal panel (11) as the illumination light (L14). As the light reflecting sheet 17, for example, a light reflecting sheet made of a resin such as polyethylene terephthalate can be used. As the light reflecting sheet 17, a light reflecting sheet obtained by depositing a metal on the surface of the substrate may be used.

Fig. 9 is a block diagram schematically showing the configuration of the control system of the liquid crystal display device 1 according to the first embodiment. 9, the liquid crystal display device 1 includes a liquid crystal panel 11, a liquid crystal panel driving section 22, a second light source 18, a first light source 101, a light source driving section 23, ). The liquid crystal panel driver 22 drives the liquid crystal panel 11. The liquid crystal panel driving unit 22 drives the liquid crystal panel 11 based on the liquid crystal panel control signal and displays the image on the liquid crystal panel 11. [ The light source driving unit 23 drives the second light source 18 and the first light source 101. The light source driving unit 23 drives the second light source 18 and the first light source 101 based on the light source control signal and adjusts the brightness of the image displayed on the liquid crystal panel 11. [ The control unit 21 controls the operation of the liquid crystal panel driver 22 and the operation of the light source driver 23. The control unit 21 performs image processing on the input video signal, and generates a liquid crystal panel control signal and a light source control signal based on the input video signal. The control unit 21 supplies the liquid crystal panel control signal to the liquid crystal panel driving unit 22 and supplies the light source control signal to the light source driving unit 23. [

The liquid crystal panel driving unit 22 changes the light transmittance of the liquid crystal layer of the liquid crystal panel 11 in units of pixels based on the liquid crystal panel control signal received from the control unit 21. [ Each pixel of the liquid crystal panel 11 is composed of three sub-pixels (first to third sub-pixels) of red (R), green (G) and blue (B), for example. The first sub-pixel has a color filter transmitting only red light, the second sub-pixel has a color filter transmitting only green light, and the third sub-pixel has a color filter transmitting only blue light.

The control unit 21 causes the liquid crystal panel 11 to display a color image by controlling the light transmittance of each sub-pixel of the liquid crystal panel 11 to the liquid crystal panel driving unit 22. [ In other words, the liquid crystal panel 11 generates image light by spatially modulating the illumination light L14 incident from the surface light-emission light guide plate 15, and emits the image light from the display surface 11a. Here, image light is light having image information.

The light-emitting planar light-guide plate 15 receives light beams L11 and L12 having different angular intensity distributions and emits from the surface 15a. In this case, the difference in the angular intensity distribution of the second light ray L11 and the first light ray L12 causes the luminance unevenness of the in-plane luminance distribution. In addition, since the second light source 18 and the first light source 101 emit different color light, in this case, the luminance unevenness of the in-plane luminance distribution appears as color unevenness on the display surface 11a.

However, the surface light-incidence side light guide plate 15 according to the first embodiment has a very narrow angular intensity distribution of the first light ray L12 emitted from the laser light emitting element by using the cylindrical mirror 102 and the angular intensity distribution regulating region 15e , And is shaped to be approximately equal to the angular intensity distribution of the second light ray L11 emitted from the LED element. Thus, the surface-emission light guide plate 15 suppresses the occurrence of color unevenness on the display surface 11a.

The second light ray L11 of cyan green and the first light ray L12 of red are incident on the light incident surface 15c of the surface light- The light rays L11 and L12 are mixed by propagating the angular intensity distribution shaping region 15e provided in the vicinity of the light incident surface 15c of the surface emitting light guide plate 15 to form a white mixed light ray L13. Thereafter, the mixed light beam L13 is emitted from the surface-emitting light guide plate 15 toward the liquid crystal panel 11 by the micro-optical element 16.

In the planar light guide plate 15 according to the first embodiment, the respective color light beams L11 and L12 are incident on the region 15f provided with the micro-optical element 16 in the same angular intensity distribution. Thus, the illumination light L14 emitted from the planar light-guiding light guide plate 15 emits a white surface-like light without color unevenness in the xy plane. Also, the control unit 21 can control the light source driver 23 to adjust the ratio of the brightness of the second light beam L11 to the brightness of the first light beam L12.

The liquid crystal display device 1 can broaden the color reproduction range by increasing the color purity of the display color. In this case, the width of the transmission wavelength band of the color filter of the liquid crystal panel 11 should be set narrow. However, if the width of the transmission wavelength band is set narrow, the amount of light transmitted through the color filter decreases. Therefore, when increasing the color purity of the display color, there arises a problem that the luminance is lowered due to the reduction of the amount of light transmitted through the color filter. In addition, a conventionally used fluorescent lamp has a peak of the emission spectrum of the red region in the wavelength region of orange. Likewise, a white LED using a yellow phosphor has a peak of the emission spectrum of the red region in a wavelength region of orange. That is, the peak of the wavelength of the red region is in the orange region deviated from the red region. Particularly, if the color purity is to be increased in red, the amount of transmitted light is very low, and the luminance is remarkably lowered.

In the liquid crystal display device 1 according to the first embodiment, the second light source 18 has an LED element for emitting a second light ray L11 of cyan color. And the second light ray L11 of the cyan color mixes the light of blue and green. Further, the first light source 101 has a monochromatic laser light emitting element for emitting a red first light ray L12. The spectrum of the first light ray L12 has, for example, a peak near 640 nm. In addition, the wavelength width of the first light beam L12 is very narrow at 1 nm in full width at half maximum, and the color purity is high. As described above, by using the red light emitting element of the first light source 101, the color purity of red can be improved. That is, the liquid crystal display device 1 can broaden the display color reproduction range.

In Embodiment 1, the case where the first light source 101 has the laser light emitting element having the peak in the vicinity of 640 nm has been described, but the present invention is not limited to this. Since the first light source 101 uses the red laser light emitting element on the shorter wavelength side, the luminosity of the wavelength rises so that the ratio of the luminance / input power can be improved, A reduction effect is obtained. Further, by using a red laser emitting element with a longer wavelength side, a color reproduction range can be widened and a clear image can be provided.

A laser light emitting device having a very narrow spectral width and capable of improving color purity has a very narrow angular intensity distribution. In a surface light source device that generates a white surface light source from this laser light emitting element and an LED element having a wide angle intensity distribution, color unevenness becomes a problem due to a narrow angle intensity distribution of the laser light.

However, in the surface light source device 100 of the liquid crystal display device 1 according to the first embodiment, the first light beam L12 emitted from the laser first light source 101 is incident on the cylindrical mirror 102 and the angular intensity distribution shaping area 15e , The angular intensity distribution of the first light ray L12 is shaped into a shape equivalent to the angular intensity distribution of the second light ray L11 emitted from the LED element. Therefore, the surface light source device 100 can obtain a white surface light with no color unevenness.

In addition, the illumination light L14 may be reflected by the first optical sheet 12, the second optical sheet 13, or the like, and may travel in the -z axis direction. The illumination light L14 is light emitted from the surface light-emitting light guide plate 15 toward the liquid crystal panel 11. [ It is necessary to use such reflected light again as the illumination light of the liquid crystal panel 11 in order to realize high luminance and low power consumption. The liquid crystal display device 1 according to the first embodiment is provided with the light reflecting sheet 17 on the -z-axis direction side of the surface light-emitting light guide plate 15. The light reflecting sheet 17 directs light traveling in the -z axis direction toward the + z axis direction. Thereby, the liquid crystal display device 1 can utilize light efficiently.

As described above, the surface light source device 100 according to the first embodiment includes the surface light-emitting light guide plate 15, the second light source 18, the first light source 101, and the cylindrical mirror 102. The second light source 18 is disposed at a position opposed to the light incidence surface (side surface) 15c of the surface light-incidence side light guide plate 15. The first light source 101 is disposed at a position closer to the rear surface 15b than the light incident surface 15c of the surface light-emitting light guide plate 15. [ The cylindrical mirror 102 has a function as an optical path changing member for guiding the first light beam L12 to the light incident surface 15c. As described above, the surface light source device 100 according to the first embodiment uses the cylindrical mirror 102 to change the traveling direction of the first light beam L12 to the direction of the light incident surface 15c of the surface-emitting light guide plate 15. Therefore, compared with the conventional configuration in which two kinds of light sources arranged in the thickness direction of the planar light-incidence side light guide plate 15 are arranged to face the light incident face 15c of the planar light-incidence side light guide plate 15, Can be made thinner.

In addition, the surface light source device 100 according to the first embodiment includes the cylindrical mirror 102 and the angular intensity distribution shaping area 15e. The cylindrical mirror 102 has a function as an optical path changing member for changing the traveling direction and angular intensity distribution of the first light beam L12. Therefore, the surface light source apparatus 100 can approximate the angular intensity distribution of the first ray L12 immediately before entering the region 15f to the angular intensity distribution of the second ray L11 immediately before entering the region 15f have. The area 15f is provided with a micro-optical element 16 on the back surface 15b side of the surface light-

As described above, the surface light source device 100 uses the cylindrical mirror 102 and the angular intensity distribution shaping area 15e to approximate the angular intensity distribution of the first ray L12 to the angular intensity distribution of the second ray L11. This suppresses the difference between the in-plane luminance distribution of the illumination light L14 produced by the second light ray L11 and the in-plane luminance distribution of the illumination light L14 produced by the first light ray L12. Then, the surface light source device 100 can reduce color unevenness of the illumination light L14. The illumination light L14 is plane light emitted from the surface 15a of the surface light- The illumination light L14 is white light added to the second light ray L11 and the first light ray L12.

Further, since the thickness of the surface emitting light guide plate 15 is reduced in the liquid crystal display device 1 having the surface light source device 100 according to the first embodiment, thinning can be realized. In addition, since the liquid crystal display device 1 can reduce the color unevenness of the surface light source device 100, the color unevenness on the display surface 11a of the liquid crystal panel 11 can be reduced and the image quality can be improved.

According to the surface light source device 100 according to the first embodiment, the controller 21 controls the light source driver 23 to adjust the brightness of the first light beam L12 and the brightness of the second light beam L11. The control unit 21 adjusts the light emission amounts of the light sources L11 and L12 based on the video signal. As a result, the power consumption of the liquid crystal display device 1 can be reduced.

In the liquid crystal display device 1, at least one kind of laser light emitting element is employed as a light source. Thereby, the liquid crystal display device 1 can provide a clear and color-free image by widening the color reproduction area.

The planar light source device 100 may be configured such that the second light source 18 is disposed on the side surface (light incident surface 15c) of the planar light guide plate 15 and the first light source 101 is disposed on the side of the planar light- And is disposed on the back surface 15b side. By separating and arranging the light sources 18 and 101 as described above, the surface light source device 100 can relieve the local temperature rise due to the heat emitted from each of the light sources 18 and 101. As a result, the surface light source device 100 can suppress a decrease in the light emission efficiency of the light sources 18 and 101 due to an increase in ambient temperature.

In the above description, the surface light source device 100 according to the first embodiment employs a configuration in which the light rays L11 and L12 are incident from the side of the short side of the surface light-emitting light guide plate 15 (light incident surface 15c). However, the planar light source device 100 may have the side surface of the long side of the planar light-incidence side light guide plate 15 as the light incidence surface. This can be achieved by appropriately changing the arrangement of the light sources 18 and 101, the position of the cylindrical mirror 102, the arrangement of the micro-optical elements 16, and the shape of the micro-optical elements 16. [

In the above description, the surface light source device 100 according to the first embodiment employs a configuration in which the light rays L11 and L12 are incident from one side (light incident surface 15c) of the surface light-emitting light guide plate 15 . However, the planar light source device 100 can also have two opposing side surfaces (for example, the light incident surface 15c and the surface 15d facing it) of the surface light-emitting light guide plate 15 as the light incident surface . This can be achieved by appropriately changing the arrangement of the light sources 18 and 101, the position of the cylindrical mirror 102, the arrangement of the micro-optical elements 16, and the shape of the micro-optical elements 16. [

The light source driver 23 of the surface light source device 100 according to the first embodiment individually controls the output of the second light source 18 and the output of the first light source 101 based on the image signal. Therefore, the surface light source device 100 can reduce power consumption. Further, the surface light source device 100 can reduce the stray light and improve the contrast. This is because stray light can be reduced by reducing extra light. Incidentally, stray light is light that passes through a path other than a regular optical path in an optical device, and therefore is harmful to a desired use.

The liquid crystal display device 1 according to the first embodiment adopts the structure in which the cyan LED element is used for the second light source 18 and the red light emitting element for the first light source 101 is adopted. However, the present invention is not limited to this. For example, the present invention can be applied to a liquid crystal display device having a plurality of different light sources, in which a light source having a wide angle intensity distribution and a light source having a narrow angle intensity distribution are provided.

For example, the present invention can be applied to a configuration in which a fluorescent lamp that emits cyan light is used for the second light source 18, and a red laser light emitting element is employed for the first light source 101. In this case, white light can be generated by the fluorescent lamp and the laser light emitting element. The present invention can also be applied to a configuration in which a blue LED element and a red LED element are used for the second light source 18 and a green laser emitting element is used for the first light source 101. [ In this case, white light can be generated by the LED element and the laser light emitting element. It is also possible to adopt a green LED element for the second light source 18 and employ a blue laser emitting element and a red laser emitting element for the first light source 101. [

Further, the surface light source device 100 according to the first embodiment employs the cylindrical mirror 102 as an optical path changing member. However, the present invention is not limited to this. Other elements may be employed if the optical path changing member has the following two functions. The first function is a function of tilting the axis of the first light ray L12 at an arbitrary angle with respect to the reference plane of the surface light-emission light guide plate 15. [ The second function is a function of widening the angular intensity distribution of the first ray L12 at an arbitrary angle.

For example, the optical path changing member can employ a convex cylindrical mirror. Further, the optical path changing member may employ a light reflecting mirror whose cross section is a polygonal shape. Further, the optical path changing member may employ a member having a reflecting film having a random concavo-convex shape on the surface.

In addition, the first function and the second function may be such that, after the first light beam L12 propagates through the angular intensity distribution shaping region 15e, the angular intensity distribution of the first light beam L12 approximates the angular intensity distribution of the second light beam L11 This is a required function. That is, the arbitrary angle intensity distribution shape means a shape after the first light ray L12 has passed through the angular intensity distribution shaping region 15e and after the light ray varying member has emerged, which is necessary for approximating the angular intensity distribution of the second light ray L11. Is an angular intensity distribution shape of the first ray L12. The arbitrary tilt angle means a tilt angle of the first light ray L12 after the first light ray L12 passes through the angular intensity distribution shaping region 15e and is required to approximate the angular intensity distribution of the second light ray L11, Lt; / RTI >

In the above description, the case in which the surface light source device 100 is used as the backlight unit of the liquid crystal display device 1 has been described. However, the surface light source device may be used for other purposes such as illumination.

(Embodiment 2)

10 is a cross-sectional view schematically showing an exemplary configuration of a liquid crystal display device 2 (including a surface light source device 200) according to the second embodiment. 11 is a cross-sectional view schematically showing the configuration of another example of the liquid crystal display device 3 (including the surface light source device 300) according to the second embodiment. In Figs. 10 and 11, the same reference numerals are assigned to the same or corresponding components as those shown in Fig. 1 (Embodiment 1). The surface light source devices 200 and 300 according to the second embodiment are different from the surface light source device 100 according to the first embodiment in that they include the light guiding member 210 for the light source.

10, the liquid crystal display devices 2 and 3 according to the second embodiment include a liquid crystal panel 11, a first optical sheet 12, a second optical sheet 13, a surface light-emitting light guide plate 15, A second light source 18, a first light source 201, a light guiding member 210 for a light source, and a cylindrical mirror 202. The light reflecting sheet 17, the second light source 18, The planar light-emitting light guide plate 15 has a micro-optical element 16 on the rear face 15b, as in the first embodiment. These components 11, 12, 13, 15, 17 and 210 are arranged in order in the thickness direction (z-axis direction) of the liquid crystal display devices 2 and 3.

The second light source 18 has a length in the z-axis direction of the light incidence surface (side surface) 15c of the surface light-incidence side light guide plate 15 (that is, (The thickness of the base 15). The second light beam L21 emitted from the second light source 18 has a wide angular intensity distribution. The angular intensity distribution of the second light ray L21 emitted from the second light source 18 of the second embodiment is a roughly Lambertian distribution having an overall angle of 120 degrees. The second light beam L21 emitted from the second light source 18 travels toward the light incident surface 15c of the surface light-emitting light guide plate 15 (approximately in the + x axis direction) (15). The second light source 18 is, for example, a light source device in which a plurality of LED elements are arranged on a straight line at regular intervals. However, the configuration of the second light source 18 is not limited to a configuration such as a straight line, an equal interval, or the like, but may have a different configuration.

The first light beam L22 emerging from the first light source 201 has a narrow angular intensity distribution with respect to the second light ray L21. The angular intensity distribution of the first light ray L22 emitted from the first light source 201 of the second embodiment is an approximately Gaussian distribution with an angular angle of about 6 degrees. The first light source 201, like the first light source 101 in the first embodiment, is a light source device in which a plurality of laser light emitting elements are arranged on a straight line at regular intervals. However, the configuration of the first light source 201 is not limited to a configuration such as a straight line, an equal interval, or the like, but may take other configurations. The first light source 201 is disposed on the back surface 15b side (-z axis direction) of the light reflection sheet 17. [ The first light source 201 is disposed so as to face the light incident surface 210a of the light guide member 210 for a light source.

The light guiding member 210 for a light source is composed of a rectangular parallelepiped 211 arranged parallel to the xy plane and a light tilting portion 212 having an inclined surface 210b inclined at about 45 degrees with respect to the xy plane have. The slope 210b is parallel to a plane having an inclination of about 45 degrees with respect to the x-y plane through the y-axis. The light guiding member 210 for a light source is, for example, a plate-shaped member having a thickness of 1 mm. The light guiding member 210 for a light source is made of a transparent material made of, for example, acrylic resin such as PMMA.

The first light beam L22 emitted from the first light source has an angular intensity distribution with an overall angle of about 6 degrees. The first light beam L22 is incident on the light-guiding member 210 for a light source, and thus becomes light having an angular intensity distribution whose full angle is about 5 degrees. The incident angle of the first light beam L22 to the inclined surface 210b is adjusted such that all of the first light ray L22 is totally reflected on the inclined surface 210b of the light guide member 210 for the light source. Thus, light loss in the light-guiding member 210 for a light source is suppressed.

For example, when a ray of light enters an air layer having a refractive index of 1.00 from an acrylic resin member having a refractive index of 1.49, the critical angle &thetas; t satisfying the total reflection condition is expressed by the following equation (1) from Snell's law.

When the full angle of the angular intensity distribution of the first ray L22 is 5 degrees (half angle is 2.5 degrees), the angle of incidence of the first ray L22 with respect to the inclined plane 210b is preferably equal to or larger than (? T + 2.5) degrees. The angle of incidence of the first ray L22 with respect to the inclined plane 210b is preferably 44.7 degrees or more so that the critical angle &thetas; t is about 42.16 degrees.

As shown in Fig. 10, the light-guiding member 210 for a light source has a light incident surface 210a, a slope surface 210b, and a light exit surface 210c. The light exit surface 210c is opposed to the light reflecting surface 202a of the cylindrical mirror 202. [ The inclined surface 210b is inclined at an angle of about 45 degrees with respect to the xy plane. The inclined plane 210b changes the traveling direction of the first light beam L22 from the -x axis direction to the + z axis direction. That is, the first ray L22 is reflected by the inclined surface 210b, and changes the traveling direction to the + z-axis direction. The refraction of the first light ray L22 is caused by the refractive index difference at the interface between the light-guiding member 210 for the light source and the air layer.

The first light beam L22 is emitted from the first light source 201. [ The first light beam L22 is incident on the light guide member 210 for a light source from the light incident surface 210a of the light guide member 210 for a light source. The first light beam L22 is totally reflected at the interface between the light guide member 210 and the air layer, and travels in the light guide member 210 for the light source in the -x axis direction. The first ray L22 reaches the inclined surface 210b, is reflected by the inclined surface 210b, and changes its traveling direction in the + z-axis direction. The first light beam L22 whose direction of advance has been changed is emitted from the light exit surface 210c and then is reflected by the cylindrical mirror 202 and is incident on the surface light emission light guide plate 15 from the light incident surface 15c. The cylindrical mirror 202 has a function as an optical path changing member.

The light reflecting surface 202a of the cylindrical mirror 202 has the same shape and function as the light reflecting surface 102a of the cylindrical mirror 102 shown in Fig. The first light beam L22 emitted from the light exit surface 210c advances toward the light reflection surface 202a of the cylindrical mirror 202. [ The angular intensity distribution of the first light ray L22 propagating while totally reflecting the light guiding member 210 for the light source is preserved. Therefore, the angular intensity distribution of the first light beam L22 emitted from the light exit surface 210c is approximately 6 degrees. That is, it is the same as the angular intensity distribution of the first light ray L22 immediately after exiting from the first light source 201. The first light beam L22 incident on the cylindrical mirror 202 is reflected by the light reflecting surface 202a and is directed to the light incident surface 15c of the surface emitting light guide plate 15 ).

The second light beam L21 emitted from the second light source 18 is incident on the surface-emission light guide plate 15 from the light incident surface 15c. Likewise, the first light ray L22 emitted from the first light source 201 is incident on the surface-emitting light guide plate 15 from the light incident surface 15c. The second light beam L21 is emitted from the second light source 18 toward the light incident surface 15c in the + x-axis direction (the right direction in Fig. 10). At this time, the axis of the second light ray L21 is substantially parallel to the reference plane (xy plane in Fig. 10) of the surface light-emitting light guide plate 15. [

The first light beam L22 propagates in the light guide member 210 for the light source and is reflected by the light reflecting surface 202a of the cylindrical mirror 202 and emitted toward the light incident surface 15c of the surface light- At this time, the cylindrical mirror 202 has the following two functions. The first function is a function of tilting the axis of the first light beam L22 at an arbitrary angle with respect to the reference plane of the planar light-guide light-guide plate 15. [ The reference plane is the xy plane of Fig. The second function is to change the progressive direction and the angular intensity distribution of the first ray L22 such that the angular intensity distribution of the first ray L22 is arbitrary in the plane parallel to the zx plane. The zx plane is a plane orthogonal to the reference plane of the planar light-emitting light guide plate 15. Hereinafter, a plane parallel to the zx plane is referred to as a plane in the thickness direction of the planar light-emitting light guide plate 15. [ Here, the axis of the ray indicates an axis in the angular direction, which is a weighted average of the angular intensity distribution in an arbitrary plane of the ray. The weighted average angle can be obtained by weighting the light intensity at each angle. When the peak position of the light intensity deviates from the center of the angular intensity distribution, the axis of the light ray does not become the angle of the peak position of the light intensity. The axis of the ray is the angle of the center position of the area of the angular intensity distribution.

The first ray L22 acts in the angular intensity distribution shaping area 15e in the same manner as the first ray L12 in the first embodiment. After the first light beam L22 is reflected by the cylindrical mirror 202, it is incident on the surface light-emission light guide plate 15. [ The axis of the first light beam L22 is inclined at an arbitrary angle with respect to the reference plane of the surface-emitting light guide plate 15. [ The first ray L22 propagates in the + x-axis direction within the angular intensity distribution shaping area 15e with this angle.

The first light ray L22 is propagated while repeating reflections on the surface 15a and the back surface 15b of the angular intensity distribution shaping region 15e. At this time, the first light ray L22 diverges due to its divergent angle, and propagates. Therefore, the first light ray L22 is folded in multiple in the plane in the thickness direction (the zx plane in Fig. 10) of the surface light-emission light guide plate 15. [ That is, it is folded at the surface 15a and the back surface 15b of the angular intensity distribution shaping area 15e and superimposed on the light diameter equal in size to the thickness of the surface light- Thus, the angular intensity distribution of the first ray L22 emitted from the angular intensity distribution shaping region 15e to the region 15f is the angular intensity distribution of the first ray L22 when it is incident on the angular intensity distribution shaping region 15e Distribution and the angular intensity distribution in which they are symmetrically bent with respect to the reference plane of the surface light-emitting light guide plate 15 are added to each other.

The second light beam L21 emitted from the second light source 18 is incident on the surface light-emission light guide plate 15 without changing the angular intensity distribution. Therefore, the second light beam L21 immediately after entering the planar light-guiding light guide plate 15 has a wide angular intensity distribution. On the other hand, the first ray L22 emitted from the first light source 201 has a narrow angular intensity distribution with respect to the second ray L21. When the first light ray L22 of the narrow angle intensity distribution is incident on the surface light-emission light guide plate 15, the difference in angular intensity distribution of the two kinds of light rays L21 and L22 in the surface light- However, the surface light source device 200 of the second embodiment uses the cylindrical mirror 202 and the angular intensity distribution shaping area 15e so that the angular intensity distribution of the first ray L22 is approximately equal to the angular intensity distribution of the second ray L21 It can be formed in an equivalent shape.

The second light ray L21 emitted from the second light source 18 is, for example, a cyan light ray. The first light beam L22 emitted from the first light source 201 is, for example, a red light beam. The second light beam L21 is incident on the surface-emitting light guide plate 15 from the light incident surface 15c. Further, the first light beam L22 is incident on the surface-emission light guide plate 15 from the light incident surface 15c. The angular intensity distribution shaping area 15e also has a function of mixing the second light beam L21 and the first light beam L22. The two types of light beams L21 and L22 are mixed by propagating through the angular intensity distribution shaping area 15e to form a mixed light beam L23. The mixed light beam L23 is, for example, a white light beam. The angular intensity distribution shaping area 15e is disposed in the vicinity of the light incident surface 15c.

The mixed light beam L23 is converted into the illumination light L24 by the micro-optical element 16 provided on the back surface 15b of the surface light- The illumination light L24 travels in the + z-axis direction and advances toward the back surface 11b of the liquid crystal panel 11. [ The illumination light L24 is transmitted through the second optical sheet 13 and the first optical sheet 12 to irradiate the back surface 11b of the liquid crystal panel 11. The first optical sheet 12 has a function of directing the illumination light L24 emitted from the light emitting surface 15a of the planar light guide plate 15 to the back surface 11b of the liquid crystal panel 11. [ The second optical sheet 13 has a function of suppressing optical effects such as minute illumination unevenness due to the illumination light L24.

The light reflecting sheet 17 is arranged to face the back surface 15b of the surface light-emitting light guide plate 15. [ Light emitted from the back surface 15b of the mixed light ray L23 middle-surface light-emitting shading plate 15 is reflected by the light reflection sheet 17 and is folded and advanced toward the back surface 15b of the surface light- Thereafter, the light passes through the surface light-emitting light guide plate 15 and is emitted as illumination light L24 from the light-emitting surface 15a toward the back surface 11b of the liquid crystal panel 11. [ Among the mixed light L23, the light ray incident on the micro optical element 16 is also emitted as the illumination light L24.

In the above description, the inclined surface 210b of the light-guiding member 210 for light source is inclined at an angle of about 45 degrees with respect to the xy plane, but the present invention is not limited thereto. The incident angle of the first ray L22 to the slope 210b can be set from the above-described critical angle? T and the total reflection condition obtained from the angle angle distribution of the angular intensity distribution of the first ray L22. In order to make the optimum light path of the first light ray L22, the inclined surfaces 210b (210b) are formed by the positional relationship between the light emitting surface 210c, the cylindrical mirror 202, May be changed. In addition, the arrangement position and shape of the cylindrical mirror 202 may be changed in place of the inclination angle of the inclined surface 210b, in order to make the optimum optical path of the first light ray L22.

Adjustment of the inclination angle of the inclined surface 210b and the arrangement position of the cylindrical mirror 202 is performed for the following three purposes. The first purpose is to allow the first light beam L22 to enter the cylindrical mirror 202 and the surface-emitting light guide plate 15 efficiently. The second object is that the axis of the first light ray L22 immediately after entering the surface light-incidence light guide plate 15 is inclined at an arbitrary angle with respect to the reference plane of the surface light-emitting light guide plate 15. [ The third object is that the first light ray L22 immediately after entering the surface light-incidence side light guide plate 15 has an arbitrary angular intensity distribution.

The positional relationship between the first light source 201 and the cylindrical mirror 202 is determined by the angular intensity distribution of the first light beam L22, the size (diameter) of the light beam of the first light beam L22, the curvature of the cylindrical mirror 202, 15 and the like. The positional relationship between the cylindrical mirror 202 and the surface light-emitting light guide plate 15 is determined by the angular intensity distribution of the first light beam L22, the size (diameter) of the light beam of the first light beam L22, the curvature of the cylindrical mirror 202, The thickness of the light guide plate 15, and the like. Therefore, when the conditions are different, it is necessary to optimize the positional relationship of each member. The positional relationship and the like are the relationships among the respective components that determine the optical path of the light beam in the arrangement position of each component and the inclination of the light reflecting surface.

10, the light-guiding member 210 for a light source is disposed in parallel with the surface-emitting light-guiding plate 15. In addition, the first light beam L22 is emitted from the first light source 201 in a direction parallel to the surface-emission light guide plate 15. [ However, the present invention is not limited to this.

For example, in the surface light source device 300 shown in Fig. 11, the light incident surface 210a of the light guide member 210 for light source is disposed so as to be farther from the light reflecting sheet 17. [ That is, the light guide member 210 for the light source is inclined with respect to the xy plane. This makes it possible to arrange the position of the light emitting end 210c of the light-guiding member 210 for the light source close to the cylindrical mirror 202 even when the first light source 201 and the members around the first light source 201 are large. Therefore, it is possible to suppress light loss that occurs until the first light beam L22 emitted from the light output end 210c enters the cylindrical mirror 202. [ The peripheral member of the first light source 201 is, for example, a holding member of the first light source 201 or the like.

In the case where the light guide member 210 for light source is inclined with respect to the surface light-emitting guide plate 15, the first light source 201 is disposed such that the axis of the first light beam L22 is parallel to the light guide member 210 for the light source . This makes it easy to control the angle of reflection of light in the optical waveguide 212. The first light source 201 is disposed so as to face the light incident surface 210a of the light guide member 210 for a light source.

The inclination angle of the inclined surface 210b is determined in consideration of the following three requirements. The first requirement is the direction of the axis of the first light beam L22 emerging from the optical breakthrough 212 with respect to the direction of the axis of the first light beam L22 incident on the optical breakthrough 212. The second requirement is the direction of the axis of the first ray L22 emerging from the cylindrical mirror 202 with respect to the direction of the axis of the first ray L22 incident on the cylindrical mirror 202. [ The third requirement is that the first ray L22 incident on the inclined plane 210b satisfies the total reflection condition on the inclined plane 210b. By satisfying these three requirements and setting the angle of the axis of the first light beam L22 and the inclined plane 210b, it is possible to suppress the light loss in the inclined plane 210b.

Further, the thinning of the light guide member 210 for the light source in the second embodiment leads to the miniaturization of the cylindrical mirror 202. [ This is because the thickness of the linear light emitted from the inclined surface 210b is reduced. That is, the diameter of the light ray in the x-axis direction becomes small. Further, the thinning of the light guide member 210 for a light source also leads to the thinning of the surface light-emitting light guide plate 15. [ This is because the dimension in the z-axis direction of the cylindrical mirror 202 becomes small. Therefore, it is preferable to use the light guiding member 210 for a light source which is thin. However, if the thickness is reduced, the rigidity of the light-guiding member 210 for the light source is lowered. Therefore, it is preferable to make the thickness of the light-guiding member 210 thinner within a range where the rigidity of the light-

The first light ray L22 emitted from the light source light guide member 210 toward the cylindrical mirror 202 travels through the light guide member 210 for the light source so that the thickness of the light guide member 210 in the zx plane is equal to the thickness of the light guide member 210 for the light source And becomes linear light of a thickness. The first light beam L22 travels in the -x axis direction while being reflected by the light exit surface 210c and the surface 210f facing the light exit surface 210c when the light guide member 210 for a light source advances. Therefore, the first light ray L22 emitted from the light output end 210c becomes a light ray having an angular intensity distribution almost equal to the angular intensity distribution immediately after the first light ray 201 is emitted. That is, the first light beam L22 emitted from the light emitting end 210c can be regarded as a secondary light source emitting from the light guiding member 210 for the light source.

On the other hand, the cross section of the light reflecting surface 202a of the cylindrical mirror 202 due to the zx plane has a concave arc shape. In this case, the angle formed by the arc-shaped tangent line of the light reflection surface 202a and each light ray constituting the light flux of the first light ray L22 has a constant width. That is, the light reflecting surface 202a has an effect of widening the parallel light. Therefore, in the surface light source devices 200 and 300 of the second embodiment, the angular intensity distribution of the first light beam L22 can be widened by the cylindrical mirror 202. [

Further, the light-guiding member 210 for a light source is not limited to a transparent member. The function of the light guide member 210 for the light source is to guide the first light beam L22 to the cylindrical mirror 202. [ If the light guiding member 210 has this function, the light guiding member 210 for the light source may have a different structure. For example, aluminum may be deposited on the inclined surface 210b, and the inclined surface 210b may be a light reflecting mirror. The light guiding member 210 for the light source may be constituted by the light guiding portion 211 and the plane mirror by using a flat mirror instead of the optical prying portion 212. The first light beam L22 emitted from the light guiding portion 211 may be directly incident on the cylindrical mirror 202 while the light guiding member 210 for the light source is configured only for the light guiding portion 211. [ The light guiding member 210 for the light source may be a flat mirror instead of the light guiding portion 211 and the optical prying portion 212.

In the second embodiment, the cylindrical mirror 202 as the optical path changing member is provided immediately after the light-guiding member 210 for the light source, but the present invention is not limited to this. Other elements may be employed if the optical path changing member has the following two functions. The first function is a function of tilting the axis of the first light beam L22 at an arbitrary angle with respect to the reference plane of the planar light-guide light-guide plate 15. [ The second function is a function of widening the angular intensity distribution of the first ray L22 at an arbitrary angle.

For example, the optical path changing member can employ a convex cylindrical mirror. Further, the optical path changing member may employ a light reflecting mirror having a polygonal cross section. Further, the optical path changing member may employ a member having a reflecting film having a random concavo-convex shape on the surface.

In addition, the first function and the second function may be set so that the angular intensity distribution of the first ray L22 approximates the angular intensity distribution of the second ray L21 after the first ray L22 has propagated through the angular intensity distribution shaping region 15e This is a required function. That is, the arbitrary angular intensity distribution shape means a shape of the first light beam L22 after passing through the angular intensity distribution shaping region 15e, which is necessary for approximating the angular intensity distribution of the second light beam L21, And the angular intensity distribution shape of the ray L22. The arbitrary tilt angle is a value obtained by dividing the first light beam L22 after emitting the light path changing member necessary for approximating the angular intensity distribution of the second light ray L21 after the first light ray L22 passes through the angular intensity distribution shaping region 15e .

In the above description, the surface light source devices 200 and 300 according to the second embodiment employ a configuration in which the light rays L21 and L22 are incident from the side (light incident surface 15c) on the short side of the surface light-emitting light guide plate 15 . However, the planar light source device 200 may be configured such that the long side of the planar light-guide light guide plate 15 is a light incidence plane. This can be achieved by suitably changing the arrangement of the light sources 18 and 201, the position of the cylindrical mirror 202, the arrangement of the micro-optical elements 16, and the shape of the micro-optical elements 16. [

In the above description, the surface light source devices 200 and 300 according to the second embodiment employ a configuration in which the light rays L21 and L22 are incident from one side (light incident surface 15c) of the surface light- . However, the planar light source device 200 may have two opposing side surfaces (for example, the light incidence surface 15c and the surface 15d facing it) of the surface light-incidence side light guide plate 15 as the light incidence surface . This is achieved by suitably changing the arrangement of the light sources 18 and 201, the position of the cylindrical mirror 202, the light-guiding member 210 for the light source, the arrangement of the micro-optical elements 16 and the shape of the micro- .

As described above, the surface light source devices 200 and 300 according to the second embodiment include the light guide member 210 for a light source, the second light source 18, the first light source 201, the light guide member 210 for a light source, And a cylindrical mirror 202. The second light source 18 is disposed at a position opposite to the light incidence surface (side surface) 15c of the planar light-incidence light guide plate 15. The first light source 201 is disposed at a position on the back surface 15b side of the surface light-emitting light guide plate 15. The light guiding member 210 for a light source has a function as an optical path changing member for guiding the first light beam L22 to the light incident surface 15c.

As described above, the surface light source devices 200 and 300 according to the second embodiment change the traveling direction of the first light beam L22 toward the light incident surface 15c of the surface-emitting light guide plate 15 by the optical path changing member. Therefore, the thickness of the planar light-emitting light guide plate 15 can be reduced compared to a conventional structure in which two kinds of light sources arranged in the thickness direction of the planar light-guide light guide plate are disposed to face the light incident face of the planar light-

The surface light source devices 200 and 300 according to the second embodiment are provided with the cylindrical mirror 202 and the angular intensity distribution shaping area 15e. The surface light source devices 200 and 300 according to the second embodiment can reduce the angular intensity distribution of the first light ray L22 immediately before entering the region 15f to the second light ray L21 immediately before entering the region 15f Of the angular intensity distribution. The cylindrical mirror 202 has a function of changing the traveling direction of the first light beam L22 and the angular intensity distribution. The region 15f is an area having the micro-optical element 16 on the back surface 15b of the surface light-emitting light guide plate 15. [

As described above, the surface light source devices 200 and 300 use the cylindrical mirror 202 and the angular intensity distribution shaping area 15e to approximate the angular intensity distribution of the first ray L22 to the angular intensity distribution of the second ray L21 have. This suppresses the difference between the in-plane luminance distribution of the illumination light L24 produced by the second light ray L21 and the in-plane luminance distribution of the illumination light L24 produced by the first light ray L22. Then, the surface light source devices 200 and 300 can reduce color unevenness of the illumination light L24. The illumination light L24 is a plane light emitted from the surface 15a of the planar light-guide light-guide plate 15. [ The illumination light L24 is white light added with the second light ray L21 and the first light ray L22.

Particularly, when an LED light source and a laser light source are employed as light sources of different types, as in Embodiment 2, in an element such as a lens element or a diffusion plate which is generally used for controlling the magnification of light, It is difficult. There are two reasons for this difficulty as follows. The first reason is that the difference in angular intensity distribution of the LED light source and the laser light source is large. The second reason is that the angular intensity distribution of the LED light source and the angular intensity distribution of the laser light source have different shapes. The angular intensity distribution of LEDs is a roughly Lambertian distribution with gentle intensity reduction as the angle around the highest intensity angle is centered. On the other hand, the angular intensity distribution of the laser light source is an approximately Gaussian distribution in which the intensity decreases sharply as the angle becomes the center around the highest intensity angle.

However, the surface light source devices 200 and 300 according to the second embodiment have the following three functions. The first function is a function that the cylindrical mirror 202 tilts the axis of the light beam from the laser light source at an arbitrary angle with respect to the reference plane of the surface light-emitting light guide plate 15. [ Here, the axis of the light beam from the LED light source is parallel to the reference plane of the planar light-guide light guide plate 15. The second function is a function that the cylindrical mirror 202 converts the light of the laser light source into light having a wide angular intensity distribution at an entire angle. The third function is a function for converting the angular intensity distribution of the light from the laser light source into the angular intensity distribution approximately equivalent to the angular intensity distribution of the light of the LED light source.

The third function is realized as follows. With the first function, the axis of the light beam from the laser light source is incident on the surface light-emission light guide plate 15 while being inclined with respect to the reference plane of the surface light-emission light guide plate 15. The light of the laser light source incident on the planar light-guiding light guide plate 15 generates light having an angular intensity distribution symmetrical with respect to the reference plane by repeating reflection in the angular intensity distribution shaping area 15e. By adding light having an angular intensity distribution symmetrical to this reference plane to each other, light of an angular intensity distribution shape equal to that of the LED light source is generated.

According to the second embodiment, mainly, after the first light ray L22 is incident on the surface light-emission light guide plate 15, it is converted into a wide angle intensity distribution equivalent to the second light ray. That is, the angular intensity distribution of the first ray L22 immediately before entering the surface-emitting light guide plate 15 has an angular intensity distribution narrower than that of the second ray. Therefore, of the first light rays L22 emitted from the cylindrical mirror 202 toward the light incident surface 15c of the surface-emitting light guide plate 15, the amount of light that does not reach the light incident surface 15c can be suppressed, It is possible to provide a configuration with a small loss.

Further, since the thickness of the surface light-emitting light guide plate 15 is reduced, the surface light source devices 200 and 300 can be thinned. Therefore, the liquid crystal display devices 2 and 3 according to the second embodiment having the surface light source devices 200 and 300 can realize thinning. Further, the surface light source devices 200 and 300 can reduce color unevenness. Therefore, in the liquid crystal display devices 2 and 3 according to the second embodiment having the surface light source devices 200 and 300, the color unevenness on the display surface 11a of the liquid crystal panel 11 can be reduced and the image quality can be improved have.

The surface light source devices 200 and 300 according to the second embodiment are provided with a light guide member 210 for a light source. Therefore, it becomes possible to dispose the two kinds of light sources 18 and 201 at a remote position. Generally, the light-emitting element employed as a light source has an electro-optical conversion efficiency of 10% to 50%. Energy that is not converted to light is heat. Here, the light emitting element is an LED element and a laser emitting element.

When the two kinds of light sources 18 and 201 are disposed in the vicinity, the heat source is concentrated in a narrow region, and heat dissipation becomes difficult. The ambient temperature of the two kinds of light sources 18 and 201 rises due to the insufficient heat radiation ability. Generally, the luminous efficiency of these light sources 18 and 201 decreases as the ambient temperature rises. Therefore, it is necessary to improve the heat radiation ability. In the liquid crystal display devices 2 and 3 according to the second embodiment, since the two kinds of light sources 18 and 201 are disposed apart from each other, the heat sources are dispersed, and the temperature control of the light sources 18 and 201 is facilitated.

Particularly, the luminescence efficiency of the laser light emitting device deteriorates with temperature change. Further, the amount of shift of the spectra with respect to the temperature change is large in the laser light emitting element. Therefore, by separating the laser light emitting element from other heat sources and arranging the laser light emitting element at one place, it becomes possible to efficiently provide the cooling mechanism and the like.

As described above, when the two types of light sources 18 and 201 are disposed at a remote position, it is effective to employ the light-guiding member 210 for the light source according to the second embodiment. At this time, it is possible to suppress the thickness increase of the surface light-emitting light guide plate 15 by providing the light guide member 210 for light source on the back surface side of the surface light-emitting light guide plate 15 as in the second embodiment.

In the surface light source devices 200 and 300, the light guiding member 210 for the light source is provided with the optical deflection portion 212 in order to guide the first light beam L22 to the cylindrical mirror 202. [ Here, the first light source 201 is arranged on the back side of the surface light-emitting light guide plate 15 together with the light guide member 210 for a light source. Further, the cylindrical mirror 202 has a function as an optical path changing member. The simplest configuration of the optical waveguide part 212 is to provide the inclined surface 210b on the light guiding member 210 for the light source. The light is totally reflected at the interface with the air layer on the inclined surface 210b to change the traveling direction of the first light beam L22.

In the planar light source devices 200 and 300, light incident on the inclined plane 210b sometimes passes through the inclined plane 210b without satisfying the total reflection condition. That is, it is necessary to suppress the optical loss due to the fact that the total reflection condition is not satisfied. In the surface light source apparatuses 200 and 300 according to the second embodiment, the first light source 201 employs a laser light emitting element having a narrow angular intensity distribution. The incidence angle intensity distribution of the first light beam L22 is preserved until the light guide member 210 advances and enters the slope surface 210b. This is because the first light ray L22 propagating in the light guide member 210 for the light source is reflected on the surface 210f which faces and is parallel to the light exit surface 210c and the light exit surface 210c, axis direction, and the axes of the first rays L22 are parallel to these surfaces. Therefore, it is easy to control the angle at which the first light beam L22 enters the inclined surface 210b. Therefore, it is possible to suppress the light loss at the inclined plane 210b of the first light beam L22, so that even when two kinds of light sources are separately arranged, it becomes possible to make a configuration with less optical loss.

Further, in the surface light source devices 200 and 300 according to the second embodiment, the light source driver 23 controls the two kinds of light sources 18 and 201 separately. This enables the light source driving section 23 to individually control the outputs of the two kinds of light sources 18 and 201 based on the image signal, thereby reducing power consumption. Further, since the amount of extra light that may be stray light is suppressed, the stray light can be reduced and the contrast can be improved.

As described above, the liquid crystal display devices 2 and 3 according to the second embodiment can suppress the increase in the thickness of the liquid crystal display devices 2 and 3 and reduce the number of light sources, . For this reason, the liquid crystal display devices 2 and 3 facilitate both high luminance and thinning. Further, since the surface-emission light guide plate 15 that uses light of different kinds of light sources as plane light is used in common, it is possible to increase the weight of the apparatus by enlarging the size of the apparatus by arranging a plurality of surface- Can be suppressed. Further, the structure in which the plurality of surface light-emitting light guide plates are arranged in a superimposed manner can suppress an increase in the number of components, reduce the number of assembling steps and reduce costs.

Further, even when the different types of light sources have different angular intensity distributions, the surface light source devices 200 and 300 can substantially coincide different angular intensity distributions. The surface light source devices 200 and 300 substantially match the angular intensity distribution of the light source having the narrow angular intensity distribution with the angular intensity distribution of the light source having the wide angular intensity distribution. Therefore, it is possible to suppress the difference in the in-plane luminance distribution of the plane-shaped light generated from the different kinds of light sources. When different kinds of light sources have different spectra, color unevenness occurs if the angular intensity distribution is not made to coincide with each other. The surface light source devices 200 and 300 can suppress color unevenness.

In order to enlarge the color reproduction range, the surface light source device may generate white light by using at least one light source having a high single color. In this case, the surface light source device employs a plurality of light sources having different angular intensity distributions. The laser light emitting device is excellent as a light source having a high single color. However, the laser light emitting element has high directivity. The surface light source devices 200 and 300 according to the present embodiment are also effective in a configuration in which the color reproduction range is widened.

(Embodiment 3)

12 is a cross-sectional view schematically showing an exemplary configuration of the liquid crystal display device 4 (including the surface light source device 400) according to the third embodiment. In Fig. 12, the same reference numerals are assigned to the same or corresponding constituent elements as those shown in Fig. 1 (embodiment 1). The surface light source device 400 according to the third embodiment is different from the surface light source device 400 according to the first embodiment having the second light source 8 and the first light source 101 as the light source in that only the first light source 301 is provided as the light source. And is different from the light source apparatus 100. [

12, the liquid crystal display device 4 according to the third embodiment has a liquid crystal panel 11, a first optical sheet 12, a second optical sheet 13, and a surface light source device 400 have. These components 11, 12, 13, and 400 are arranged in order in the thickness direction (-z axis direction) of the liquid crystal display device 4. [

The planar light source device 400 has a planar light-emitting planar light-guide plate 15, a light reflective sheet 17, a first light source 301, and a cylindrical mirror 102 in the form of a thin plate. The cylindrical mirror 102 has a function as an optical path changing member. The planar light-emitting light guide plate 15 has a micro-optical element 16 on its rear face 15b as in the first embodiment.

The first light source 301 is disposed on the back surface 15b side (-z axis direction) of the surface light-emitting light guide plate 15. The first light source 301 is a light source device in which a plurality of laser light emitting elements are arranged at regular intervals in the y axis direction. The light emitting portion for emitting the first light ray L32 of the first light source 301 is arranged to face the light reflecting surface 102a of the cylindrical mirror 102. [

The laser light emitted from the laser light emitting element is excellent in monochromaticity. Therefore, by adopting the laser light emitting element as the light source of the liquid crystal display device 4, it becomes possible to provide the liquid crystal display device 4 which illuminates a clear image having a wide color reproduction range.

The laser emitting element has high directivity. For example, the first light ray L32 emitted from the first light source 301 in the third embodiment is incident on a plane (zx plane in Fig. 12) that widens in the thickness direction of the surface light-emitting light guide plate 15, And has an angular intensity distribution of approximately Gaussian distribution. In general, the high directivity of the laser light is obtained by the use efficiency of the light (that is, the light utilization efficiency of the surface light source device) in the surface light source device (that is, the side light type surface light source device) that generates surface light by using multiple reflections in the surface light- , The ratio of the amount of light emitted from the light exit surface (first surface) toward the liquid crystal panel to the light amount of the light incident on the light incident surface (third surface) of the surface light-emitting light guide plate) . Therefore, when employing a laser light emitting element as a light source of the side light type surface light source device, it is preferable to lower the directivity of the laser light, that is, broaden the light distribution.

The cylindrical mirror 102 included in the surface light source device 400 according to the third embodiment has the following two functions. The first function is a function of tilting the light beam axis of the first light ray L32 at a desired angle with respect to a reference plane parallel to the first surface 15a of the surface-emitting light guide plate 15. [ This desired angle can be set at an arbitrary angle by appropriately selecting the shape and arrangement of the light reflection surface 102a of the cylindrical mirror 102. [ The reference plane is the xy plane in Fig. The second function is to change the progressive direction and the angular intensity distribution of the first ray L32 such that the angular intensity distribution of the first ray L32 becomes a desired shape on a plane parallel to the zx plane. In order to make the angular intensity distribution into a desired shape, the shape and arrangement of the light reflecting surface 102a of the cylindrical mirror 102 can be appropriately selected and set to an arbitrary shape. The zx plane is a plane orthogonal to the reference plane of the planar light-emitting light guide plate 15.

The surface emitting light guide plate 15 provided in the third embodiment has an angular intensity distribution shaping area 15e (first area) having a predetermined length from the light incident surface 15c toward the center of the surface light emitting light guide plate 15 Respectively.

In the surface light source device 400 according to the third embodiment, the light beam L32 having high directivity emitted from the light source 301 is passed through the cylindrical mirror 102 as the optical path changing member and the angular intensity distribution shaping area 15e , It is possible to convert it into light having a wide angle intensity distribution. The detailed behavior of the first light beam L32 transmitted through the cylindrical mirror 102 and the angular intensity distribution shaping area 15e is the same as described in the first embodiment.

As described above, the first light beam L32 emitted from the first light source 301 can broaden the angular intensity distribution by transmitting the cylindrical mirror 102, which is an optical path changing member, and the angular intensity distribution regulating region 15e. Therefore, the light ray L33 emitted from the angular intensity distribution shaping region 15e has a wide angular intensity distribution and is incident on a region (second region) that generates light in a planar shape of the surface light-emission light guide plate 15. [

Therefore, even when a laser light emitting element is employed as the light source in the surface light source device that generates planar light by using multiple reflection in the planar light emitting light guide plate, it is possible to suppress the lowering of the light utilization efficiency. Therefore, the liquid crystal display device 4 including the surface light source device 400 can realize a liquid crystal display device which can provide a clear image by employing a laser light emitting element as a light source, and realize a low power consumption liquid crystal display device.

For example, as the first light source 301 in the third embodiment, by providing the laser light emitting element that emits red, green, and blue light, it is possible to generate white light with a very wide color reproduction range It becomes possible to provide a surface light source device.

Further, as the first light source 301, a configuration in which a light source having a high directivity including a lens in the LED element may be provided. For example, by providing a monochromatic LED element that emits red, green, and blue light, it is possible to provide a surface light source device that can generate white surface light with a wide color reproduction range. However, in order to obtain a wider color reproduction range, it is preferable to employ a laser light emitting element having superior monochromaticity.

The surface light source device 400 according to the third embodiment employs the cylindrical mirror 102 as an optical path changing member. However, the present invention is not limited to this. If the optical path changing member has the following two functions, another element may be employed. The first function is a function of tilting the light axis of the first light ray L32 at an arbitrary angle with respect to the reference plane of the surface light-emission light guide plate 15. [ The second function is a function of widening the angular intensity distribution of the first ray L32 at an arbitrary angle.

The surface light source device 400 according to the third embodiment has a structure in which a light guide member for a light source is provided between the first light source and the optical path changing member like the surface light source device 200 or 300 according to the second embodiment It is also good. More specifically, in place of the surface light source device 400 shown in Fig. 12, the surface light source device 410 having the light guiding member 210 for a light source shown in Fig. 13, or the surface light source device 410 shown in Fig. A surface light source device 420 having a light source 210 may be employed.

In the above-described embodiments, terms indicating the positional relationship between components such as " parallel " and " vertical " or the shape of the component may be used. In addition, there is a case where the term "roughly (approximately)" or "almost", which is approximately square, approximately 90 degrees and approximately parallel, is used. These values include ranges in consideration of manufacturing tolerances and variations in assemblies. For example, " approximately -z-axis direction " is a term including manufacturing tolerances and variations in assemblies. For this reason, even if the appended claims do not describe " about (approximate) ", for example, they include a range in consideration of manufacturing tolerances and variations in assemblies. In addition, when "approximately (approx.)" Is described in the claims, it includes a range in consideration of manufacturing tolerances and variations in assemblies.

1, 2, 3, 4, 5, 6: liquid crystal display
11: liquid crystal panel
11a:
11b: rear surface
12: first optical sheet
13: second optical sheet
14: optical member
15: plane light-
15a: surface (first surface)
15b: rear surface (second surface)
15c: light incidence plane (third plane)
15e: angular intensity distribution shaping area (first area)
15f: area (second area)
16: Micro optical element
17: Light reflecting sheet
18: second light source
102, 202: cylindrical mirror
102a and 202a:
100, 200, 300, 400, 410, 420: plane light source device
101, 201, 301: a first light source
210: light guiding member for light source
210a: light incidence plane
210b:
210c: light emitting surface
210f: cotton
211:
212: optical break
L11, L21: the second ray
L12, L22, L32, L33:
L13, L23: Mixed ray
L14: Lighting
500a, 500b, 510: Angular intensity distribution

Claims (11)

A planar light-emitting light guide plate having a first surface, a second surface opposite to the first surface, and a third surface connecting sides of the first surface and sides of the second surface,
A first light source for emitting a first light beam,
And a second light source for emitting a second light ray incident on the third surface of the surface light-
Lt; / RTI >
The angular intensity distribution of the second light ray immediately after the second light ray is emitted from the second light source is larger than the angular intensity distribution of the first light ray immediately after the first light ray is emitted from the first light source,
The surface light-
A first region for propagating the first light ray and the second light ray incident from the third surface and widening the angular intensity distribution of the first light ray,
And a second region for emitting the first light beam and the second light beam with the angular intensity distribution widened from the first surface as plane light
And the surface light source device.
The method according to claim 1,
Wherein the first region is an angular intensity distribution shaping region disposed between the third surface and the second region
And the surface light source device.
3. The method according to claim 1 or 2,
The first region is a region that reflects the first light ray and the second light ray incident from the third surface on the first surface and the second surface
And the surface light source device.
3. The method according to claim 1 or 2,
And the traveling direction of the first light beam immediately before entering the third surface is a direction inclined with respect to a reference plane parallel to the first surface
And the surface light source device.
3. The method according to claim 1 or 2,
Further comprising an optical path changing member disposed opposite to the third surface,
Wherein the optical path changing member has a light reflecting surface for directing the traveling direction of the first light ray to the third surface and widening the angular intensity distribution of the first light ray
And the surface light source device.
6. The method of claim 5,
Further comprising a light guide member for a light source for directing the traveling direction of the central ray of the first light beam to the light reflection surface of the light path changing member
And the surface light source device.
3. The method according to claim 1 or 2,
Wherein the first light source has one or more laser light emitting elements
And the surface light source device.
3. The method according to claim 1 or 2,
Further comprising an optical path changing member disposed opposite to the third surface,
The light intensity distribution of the first light beam immediately after passing through the first region of the surface light-guiding light guide plate is equal to the angular intensity distribution of the second light ray immediately after passing through the first region, Changing the angular intensity distribution of the first light beam by the changing member and the first region
And the surface light source device.
3. The method according to claim 1 or 2,
Wherein the second light source has one or more LED elements
And the surface light source device.
A liquid crystal panel,
The surface light source device according to claim 1 or 2, wherein the surface light source device
And the liquid crystal display device. delete

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