JP2015035252A - Light source device, surface light source device, display device, and lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light source device that has superior uniaxial directivity.SOLUTION: A light source device 1 includes a light source part 2 which emits light having different directivity in two mutually orthogonal axial directions and an anisotropic scattering sheet 3 (anisotropic scattering part) which has different mutually different scattering properties in two mutually orthogonal axial directions, and emits light made incident from a light source part as scattered light, the axial direction in which the light emitted from the light source part 2 has low directivity being substantially aligned with the axial direction in which the anisotropic scattering sheet 3 has high scattering properties.

Description

  The present invention relates to a light source device, a surface light source device, a display device, and an illumination device.

  Conventionally, an optical element that imparts directivity to light emitted from a light source has been proposed. For example, Patent Document 1 below discloses a monolithic optical element in which a plurality of microstructures are formed on one surface of a parabolic convex lens. In this optical element, a plurality of microstructures are integrally formed on the side surface opposite to the parabolic convex lens surface. The parabolic convex lens surface provides macro optical characteristics of the lens, and the micro structure provides light diffusion characteristics so that a smoothly varying intensity distribution can be obtained.

  A surface light source device used for a backlight of a liquid crystal display has been conventionally proposed. For example, Patent Literature 2 below discloses a backlight assembly having a diffuser surface structure on the front and rear surfaces of an optical waveguide (light guide plate). According to this backlight assembly, it is possible to obtain a light output pattern diffused into an elongated elliptical shape.

JP 2009-157404 A Japanese Patent No. 4687730

  A surface light source device used for a backlight of a liquid crystal display or the like is required to have high directivity in all directions in order to improve display characteristics such as color shift and contrast ratio. In that case, a method of obtaining biaxial directivity as a whole surface light source device by combining a light source having uniaxial directivity and a light guide plate having uniaxial directivity in a direction orthogonal to the directivity of the light source Can be considered.

  However, even if the optical element of Patent Document 1 is applied to this type of surface light source device, good uniaxial directivity cannot be obtained. The reason is that this optical element uses a transmissive convex lens that transmits light, and it is difficult for a transmissive lens that utilizes a refraction phenomenon to have high directivity only in one axial direction.

  In addition, when the light guide plate of Patent Document 2 is applied to the above surface light source device, the light incident from the light source is directed to the front and rear surfaces of the light guide plate even if the light incident portion of the light guide plate has directivity. Multiple scattering of light occurs due to the action of the provided diffuser surface structure, and the directivity is disturbed.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a light source device having excellent uniaxial directivity. Moreover, it aims at providing the surface light source device excellent in biaxial directivity. It is another object of the present invention to provide a display device and an illumination device that are equipped with this type of light source device or surface light source device and have excellent characteristics.

  In order to achieve the above object, the light source device of the present invention has a light source unit that emits light having different directivities in two axial directions orthogonal to each other and a scattering property different from each other in two axial directions orthogonal to each other. And an anisotropic scattering unit that emits light incident from the light source unit as scattered light, and an axial direction in which directivity of light emitted from the light source unit is low, and scattering of the anisotropic scattering unit It is characterized in that the axial direction with high properties is generally matched.

  The light source device of the present invention is characterized in that the anisotropic scattering portion is formed of an anisotropic scattering sheet in which a plurality of irregular shapes are formed aperiodically.

  The light source device of the present invention is characterized in that the anisotropic scattering sheet is formed by extending a concavo-convex structure in a uniaxial direction.

  The light source device of the present invention is characterized in that the anisotropic scattering part is composed of a lenticular lens in which a plurality of columnar lenses are arranged.

  The light source device of the present invention is characterized in that a reflecting member that reflects light emitted from the anisotropic scattering portion is provided in an axial direction in which the anisotropic scattering portion has high scattering properties.

  In the light source device of the present invention, a regulating member that regulates the spread of light emitted from the anisotropic scattering portion in the axial direction with low scattering property is provided on the light emission side of the anisotropic scattering portion. It is characterized by.

  In the light source device of the present invention, the light source unit includes a light emitting element, a concave mirror that reflects light emitted from the light emitting element, and a convex lens that is disposed in a recess of the concave mirror, and the concave mirror is provided. The cross-sectional shape when cut along a predetermined plane has at least a part of a curved shape having a focal point, the focal point is located on the light emitting surface of the light emitting element, and the convex lens is parallel to the predetermined plane. It has a pair of parallel planes, and light from the light emitting element is reflected by the concave mirror after passing through the convex lens, and is emitted from the light exit surface of the convex lens through the convex lens.

  The light source device of the present invention is characterized in that the anisotropic scattering portion is formed of a concavo-convex structure formed on the light exit surface of the convex lens.

  In the light source device of the present invention, the light emitting element is a light emitting diode.

  The light source device of the present invention is characterized in that the curved shape is substantially a parabola.

  In the light source device of the present invention, the concave mirror is made of a metal film or a dielectric multilayer film.

  The surface light source device of the present invention includes the above-described light source device of the present invention and a light guide that allows light emitted from the light source device to be incident from an end surface and to be emitted from the main surface while propagating inside. It is characterized by.

  The surface light source device of the present invention is characterized in that the anisotropic scattering part is composed of a concavo-convex structure formed on the end face of the light guide.

  The surface light source device of the present invention is characterized in that the light guide has a reflection surface that forms a predetermined inclination angle with respect to the main surface in the light propagation direction.

  In the surface light source device of the present invention, the light guide has a wedge shape in which the thickness decreases toward the side farther from the side closer to the end surface, and the entire surface facing the main surface is the reflective surface. Features.

  In the surface light source device of the present invention, the light guide has a plurality of prism structures on a surface facing the main surface, and one inclined surface of the prism structure is the reflection surface. To do.

  The surface light source device of the present invention is provided with a direction changing member that changes the traveling direction of light emitted from the main surface of the light guide to a direction closer to the normal line of the main surface. .

  A display device according to the present invention includes the above surface light source device according to the present invention and a display element that performs display using light emitted from the surface light source device.

  The illumination device of the present invention includes the light source device of the present invention.

  The illumination device of the present invention includes the surface light source device of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, the light source device excellent in uniaxial directivity can be provided. Moreover, the surface light source device excellent in biaxial directivity can be provided. In addition, it is possible to provide a display device and an illumination device that are provided with this type of light source device or surface light source device and have excellent characteristics.

It is a perspective view which shows the light source device of 1st Embodiment of this invention. It is a top view of the light source device of this embodiment. It is sectional drawing of the light source device of this embodiment, and is sectional drawing which follows the A-A 'line of FIG. It is a figure which shows the surface structure of the anisotropic scattering sheet used for the light source device of this embodiment. (A), (B) is a figure which shows the path | route of the light in the light source device of this embodiment. (A), (B) is a figure which shows the path | route of the light in the light source device of a comparative example. (A) The figure which shows the luminance distribution in the light source device of this embodiment, (B) The figure which shows the luminance distribution in the light source device of a comparative example. (A) Sectional drawing which shows the 1st modification of the light source device of this embodiment, (B) Sectional drawing which shows the 2nd modification of the light source device of this embodiment. It is a disassembled perspective view which shows the surface light source device of 2nd Embodiment of this invention. It is sectional drawing of the surface light source device of this embodiment, and is sectional drawing which follows the A-A 'line of FIG. It is a figure which shows the path | route of the light inside the light guide in the surface light source device of this embodiment. (A) The figure which shows the illuminance distribution in the surface light source device of a comparative example, (B) The figure which shows the illuminance distribution in the surface light source device of this embodiment. It is sectional drawing which shows the modification of the surface light source device of this embodiment. It is a disassembled perspective view which shows the surface light source device of 3rd Embodiment of this invention. It is sectional drawing of the surface light source device of this embodiment, and is sectional drawing which follows the A-A 'line of FIG. It is sectional drawing which shows the 1st modification of the surface light source device of this embodiment. It is sectional drawing which shows the 2nd modification of the surface light source device of this embodiment. It is sectional drawing which shows the display apparatus of 4th Embodiment of this invention. It is sectional drawing which shows the display apparatus of 5th Embodiment of this invention. It is a front view which shows the display apparatus of the said embodiment. It is sectional drawing which shows the illuminating device of 6th Embodiment of this invention. It is sectional drawing which shows the illuminating device of 7th Embodiment of this invention.

[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
In the present embodiment, an example of a light source device suitable for use as, for example, a backlight of a liquid crystal display device is shown.
FIG. 1 is a perspective view showing the light source device of the present embodiment. FIG. 2 is a plan view of the light source device of the present embodiment. FIG. 3 is a cross-sectional view of the light source device of the present embodiment, and is a cross-sectional view taken along the line AA ′ of FIG. FIG. 4 is a view showing the surface structure of the anisotropic scattering sheet used in the light source device of the present embodiment.
In the following drawings, in order to make each component easy to see, the scale of the size may be varied depending on the component.

  The light source device 1 of this embodiment is provided with the light source part 2 and the anisotropic scattering sheet 3 (anisotropic scattering part), as shown in FIGS. The light source unit 2 includes an LED 4 (light emitting element), a cylindrical lens 5 (convex lens), and a concave mirror 6. The cylindrical lens 5 is made of a resin such as an acrylic resin. The cylindrical lens 5 is a so-called plano-convex lens in which one is a convex surface and the other is a flat surface. Since the light L is emitted from the flat surface 5a, the flat surface 5a is hereinafter referred to as a light emission surface. On the other hand, the convex surface has a curved surface 5b that is gently curved and two flat side surfaces 5c that are continuous to both ends of the curved surface 5b.

  Looking at the cross-sectional shape of the cylindrical lens 5 cut along the xz plane, the curved surface 5b of the convex surface has a curved shape having a focal point P as shown in FIG. In the case of this embodiment, specifically, the cross-sectional shape of the curved surface 5b is parabolic. On the other hand, when the cross-sectional shape obtained by cutting the cylindrical lens 5 along the yz plane is viewed, the curved surface 5b has a linear shape as shown in FIG. That is, the curved surface 5b of the cylindrical lens 5 is a paraboloid that is curved in the xz plane and not curved in the yz plane. As shown in FIG. 3, the upper surface 5d and the lower surface 5e of the cylindrical lens 5 are a pair of parallel planes parallel to the xz plane.

  A concave mirror 6 is provided along the curved surface 5 b of the cylindrical lens 5. The concave mirror 6 is made of a metal film having a high light reflectivity such as aluminum or a dielectric multilayer film directly formed on the curved surface 5b of the cylindrical lens 5. In other words, the cylindrical lens 5 is disposed in a recess inside the concave mirror 6. Thus, since the curved surface 5b of the cylindrical lens 5 and the concave mirror 6 are in close contact, the shape of the concave mirror 6 is a paraboloid reflecting the shape of the curved surface 5b. Therefore, the focal position of the concave mirror 6 coincides with the focal position of the cylindrical lens 5. The position of the focal point is indicated by a point P in FIG. Instead of directly forming the concave mirror 6 on the curved surface 5b of the cylindrical lens 5, a configuration may be adopted in which a concave mirror manufactured separately from the cylindrical lens is bonded.

  As shown in FIG. 3, the light exit surface 5 a of the cylindrical lens 5 is provided with a through hole 7 having a depth that allows the LED 4 to be inserted therein. The cross-sectional shape of the through-hole 7 on the concave mirror 6 side when the cylindrical lens 5 is cut along the xz plane is rounded into an arc shape. An LED 4 is disposed inside the through hole 7. The LED 4 is arranged with the light emitting surface 4a facing the concave mirror 6, and the back surface opposite to the light emitting surface 4a is fixed with an adhesive or the like.

  The height Y1 (dimension in the y-axis direction) of the LED 4 is smaller than the thickness Y2 (dimension in the y-axis direction) of the cylindrical lens 5, and is about 1/3 of the thickness of the cylindrical lens 5, for example. The LED 4 and the concave mirror 6 and the cylindrical lens 5 are set to have a positional relationship, dimensions, shape, and the like so that the focal point P of the concave mirror 6 and the cylindrical lens 5 is positioned on the light emitting surface 4a of the LED 4.

  Since the light emitting surface 4 a of the LED 4 faces the concave mirror 6, almost all of the light emitted from the light emitting surface 4 a of the LED 4 passes through the cylindrical lens 5 toward the concave mirror 6 and is reflected by the concave mirror 6. The light reflected by the concave mirror 6 passes through the cylindrical lens 5 again and is emitted from the light exit surface 5 a of the cylindrical lens 5. Therefore, among the light emitted from the light emitting surface 4 a of the LED 4, there is almost no light emitted directly without being reflected by the concave mirror 6. The LED 4 is not particularly directional, and a general LED that emits light at a predetermined diffusion angle can be used. Of the convex surface of the cylindrical lens 5, at least a paraboloid is provided up to the position where the light emitted from the LED 4 reaches at the maximum diffusion angle, and the concave mirror 6 exists. Therefore, the portion where the light from the LED 4 does not reach is a flat side surface 5c, and the concave mirror 6 does not exist.

Here, the directivity of light emitted from the light source unit 2 having the above configuration will be described.
Since the light emitting surface 4a of the LED 4 has a finite size, not all points on the light emitting surface 4a necessarily coincide with the positions of the focal point P of the concave mirror 6 and the cylindrical lens 5. However, for the sake of simplicity, the following description will be made assuming that the area of the light emitting surface 4a is sufficiently small and the light emitting surface 4a coincides with the focal point P.

The light L emitted from the light emitting surface 4 a of the LED 4 is directed to the concave mirror 6 with a predetermined diffusion angle and reflected by the concave mirror 6. Here, the behavior of light in a plane (xz plane) parallel to the upper surface 5d and the lower surface 5e of the cylindrical lens 5 will be considered.
As shown in FIG. 2, since the position of the light emitting surface 4 a coincides with the focal point P, the light L emitted from the LED 4 is incident on the concave mirror 6 at any angle. Then, the light travels in a direction parallel to the optical axis of the concave mirror 6. Therefore, the diffused light emitted from the light emitting surface 4a of the LED 4 is converted to parallel light reflected by the concave mirror 6, that is, light having high directivity, and emitted from the light emitting surface 5a of the cylindrical lens 5. Is done.

Next, the behavior of light in a plane (yz plane) perpendicular to the upper surface 5d and the lower surface 5e of the cylindrical lens 5 will be considered.
As shown in FIG. 3, as far as viewing in the yz plane, since the concave mirror 6 has no curvature, the concave mirror 6 functions like a plane mirror. That is, the light L is reflected by the concave mirror 6 at a reflection angle equal to the incident angle. Therefore, the light L is emitted from the light emitting surface 5a of the cylindrical lens 5 while maintaining the diffusion angle immediately after being emitted from the light emitting surface 4a of the LED 4.

  In summary, when the light is emitted from the light exit surface 5a of the cylindrical lens 5 (light source unit 2), the light L is in the x-axis in a plane (xz plane) parallel to the upper surface 5d and the lower surface 5e of the cylindrical lens 5. High directivity in the direction, and low directivity in the y-axis direction in a plane (yz plane) perpendicular to the upper surface 5d and the lower surface 5e of the cylindrical lens 5. In this way, light L having different directivities in two axial directions orthogonal to each other is incident on the anisotropic diffusion sheet 3 from the light source unit 2.

  An anisotropic scattering sheet 3 is installed on the light exit surface of the light source unit 2, that is, the light exit surface 5 a of the cylindrical lens 5. As shown in FIG. 4, the anisotropic scattering sheet 3 has a plurality of uneven structures formed on the surface thereof aperiodically. Each unevenness extends in one axial direction, and is formed such that the average pitch of the unevenness in two axial directions orthogonal to each other in the plane is different. With such a configuration, the anisotropic scattering sheet 3 has different scattering properties in the two orthogonal directions such that the full width at half maximum of the scattered light in the two orthogonal directions is 30 ° and 1 °, for example. It will have. As an example of the anisotropic scattering sheet 3, as shown in FIG. 4, there is a sheet made of a resin sheet such as polycarbonate or acrylic, and the sheet surface unevenness is elongated in one direction, and is orthogonal to the unevenness extending direction. The direction is a highly scattering direction.

  As the anisotropic scattering sheet 3, for example, a light diffusion control film (trade name: LSD) manufactured by Luminit Co., etc. can be used. Light diffusion control film in which the full width at half maximum of scattered light in two axial directions orthogonal to each other is 40 ° on the high scattering side and 0.2 ° on the low scattering side, or 60 ° on the high scattering side and 1 ° on the low scattering side Is commercially available. Or it can replace with what has an uneven | corrugated shape on the surface, and can use the light-scattering film which disperse | distributed the particle | grains whose aspect-ratio is about 5-500 in a continuous layer.

In the present embodiment, the anisotropic scattering sheet 3 is arranged so that the axial direction with high scattering properties substantially coincides with the thickness direction (y-axis direction) of the cylindrical lens 5. That is, the axial direction in which the directivity of light emitted from the light source unit 2 is low and the axial direction in which the anisotropic scattering sheet 3 has high scattering properties substantially coincide with each other.
The anisotropic scattering sheet 3 may be disposed between the cylindrical lens 5 and an air layer. That is, the anisotropic scattering sheet 3 may be arranged away from the cylindrical lens 5. Alternatively, the anisotropic scattering sheet 3 may be disposed in close contact with the cylindrical lens 5. Further, when the anisotropic scattering sheet 3 is in close contact with the cylindrical lens 5, the anisotropic scattering sheet 3 may be optically bonded to the cylindrical lens 5 with an optical adhesive. Further, when used in a surface light source device to be described later, the anisotropic scattering sheet 3 may be optically bonded to the light guide with an optical adhesive, or may be sandwiched between the cylindrical lens 5 and the light guide. It may be fixed.

Hereinafter, the operation of the light source device 1 of the present embodiment will be described.
First, as shown in FIGS. 6A and 6B, consider a comparative light source device having no anisotropic scattering sheet.
When the height of the LED (dimension in the y-axis direction) is smaller than the thickness of the cylindrical lens 8 (dimension in the y-axis direction), focusing on the light incident on one point on the light exit surface of the cylindrical lens, the xz plane The light emission angle is uniquely determined by the number of reflections on the parallel reflecting surfaces (the upper surface and the lower surface of the cylindrical lens).

  For example, in FIG. 6A, focusing on the point Q1 on the light exit surface 101a of the cylindrical lens 101, the broken line arrow L0 among the light emitted from the LED 102 indicates the locus of light with zero reflections. . A two-dot chain line arrow L1 indicates the trajectory of light whose number of reflections is once on the upper surface 101d and the lower surface 101e of the cylindrical lens 101. A one-dot chain line arrow L2 indicates the locus of light whose number of reflections is twice on the upper surface 101d and the lower surface 101e. Thus, the emission angle of light emitted from the point Q1 on the light emission surface takes a discrete value in the y-axis direction according to the number of reflections.

  Next, as shown in FIG. 6B, when the light emission position is moved from the point Q1 to the point Q2, the locus of the light L1 with zero reflections is changed, and the number of reflections is the same. The emission angle of light emitted from the point Q2 on the light emission surface 101a is different from the emission angle of light emitted from the point Q1.

  That is, the light emission angle shows a discrete distribution in the y-axis direction, and spatial variation occurs for each light emission position. When the emitted light from such a light source unit is viewed from a position that is a predetermined distance away from the light exit surface in the z-axis direction, for example, the illuminance distribution of the emitted light becomes discrete. As a result, points with high illuminance and points with low illuminance appear alternately along the y-axis direction, and illuminance non-uniformity becomes more prominent.

  On the other hand, since the light source device 1 of the present embodiment includes the anisotropic scattering sheet 3 having high scattering properties in the y-axis direction, as shown in FIGS. As a result of interpolating the low illuminance portion of the intended illuminance distribution by light scattering, the illuminance distribution in the y-axis direction is made uniform. On the other hand, since the scattering property in the x-axis direction of the anisotropic scattering sheet 3 is low, the high directivity in the x-axis direction of the light emitted from the light source unit 2 is maintained.

In order to demonstrate the effect of the light source device of the present embodiment, the present inventors do not include the light source device of the present embodiment including the anisotropic scattering sheet and the anisotropic scattering sheet using optical simulation. The light intensity distribution of the emitted light was compared with the light source device of the comparative example. The results are shown in FIGS. 7 (A) and 7 (B).
The curves shown in FIGS. 7A and 7B are isoluminous curves. The horizontal axes of FIGS. 7A and 7B indicate polar angles (°) in the x-axis direction when the normal direction of the light exit surface is 0 °. 7A and 7B, the vertical axis indicates the polar angle (°) in the y-axis direction when the normal direction of the light exit surface is 0 °.

  As simulation conditions, LED width X1 (dimension in the x-axis direction, see FIG. 2) is 1.4 mm, LED height Y1 (dimension in the y-axis direction, see FIG. 3) is 1 mm, and LED depth Z1 (z-axis). 3 mm), the cylindrical lens width X2 (x-axis dimension, see FIG. 2) is 40 mm, and the cylindrical lens height Y2 (y-axis dimension, see FIG. 3). 3 mm, the distance Z2 from the light emitting surface of the LED to the light exit surface of the cylindrical lens (dimension in the z-axis direction, see FIG. 2) is 3 mm, and the focal length Z3 of the cylindrical lens (dimension in the z-axis direction, see FIG. 2) is 10 mm. , And. As for the scattering property of the anisotropic scattering sheet, the full width at half maximum of scattered light in the y-axis direction was 30 °, and the full width at half maximum of scattered light in the x-axis direction was 1 °.

  As a result of optical simulation, it was found that in the light source device of the comparative example, the luminous intensity distribution of the emitted light in the y-axis direction was discrete as shown in FIG. 7B. On the other hand, in the light source device of the present embodiment, as shown in FIG. 7A, it has been found that the luminous intensity distribution of the emitted light in the y-axis direction becomes continuous and the luminous intensity distribution becomes more uniform. Further, since the luminous intensity distribution of the emitted light in the x-axis direction is not substantially changed, it has been found that high directivity in the x-axis direction is maintained.

[First Modification]
In the present embodiment, an anisotropic scattering sheet is used as a means for imparting an anisotropic scattering function, but instead of this configuration, a light source device shown in FIG. 8A may be used.
As shown in FIG. 8A, the light source device 10 of the present modification is provided with a concavo-convex structure 12 for causing anisotropic scattering on the light exit surface 11a of the cylindrical lens 11. That is, the concavo-convex structure as shown in FIG. 4 is formed on the light exit surface 11a of the cylindrical lens 11 itself. Such a configuration can be realized, for example, by giving a shape obtained by inverting the concavo-convex structure 12 to a mold used when manufacturing the cylindrical lens 11 in advance and performing injection molding using the mold. It is. According to this structure, an anisotropic scattering sheet becomes unnecessary.

[Second Modification]
Instead of the light source device of this embodiment, the light source device shown in FIG. 8B may be used.
As shown in FIG. 8B, the light source device 15 of the present modification is provided with a louver 16 (regulating member) on the light exit side of the anisotropic scattering sheet 3. The louver 16 has a slit (opening, not shown) extending in the y-axis direction. The louver 16 functions as a regulating member that regulates the spread in the axial direction (x-axis direction) where the scattering property of light emitted from the anisotropic scattering sheet 3 is low. Note that the member that restricts the spread of light in the axial direction (x-axis direction) with low scattering is not limited to the louver 16, and other optical members having a function of focusing light in one direction may be used.

  The light emitted from the anisotropic scattering sheet 3 is slightly scattered not only in the axial direction (y-axis direction) with high scattering properties but also in the axial direction (x-axis direction) with low scattering properties. As a result, the scattered light component in the x-axis direction slightly reduces the directivity in the x-axis direction. However, in the light source device 15 of the present modification, since the louver 16 is provided on the light emitting side of the anisotropic scattering sheet 3, high directivity in the x-axis direction is reliably maintained.

[Second Embodiment]
Hereinafter, a second embodiment of the present invention will be described with reference to FIGS.
The present embodiment is an embodiment of a surface light source device that combines the light source device of the first embodiment and a light guide.
FIG. 9 is an exploded perspective view showing the surface light source device of this embodiment. FIG. 10 is a cross-sectional view of the surface light source device of the present embodiment, and is a cross-sectional view taken along the line AA ′ of FIG.
In FIG. 9 and FIG. 10, the same code | symbol is attached | subjected to the same component as drawing used in 1st Embodiment, and description is abbreviate | omitted.

  The surface light source device 19 of this embodiment is provided with the light source device 1, the light guide 20, the reflective mirror 21, and the prism sheet 22 (direction changing member) as shown in FIG. 9, FIG. Yes. The light guide 20 has a function of causing light emitted from the light source device 1 to enter from the end face and to be emitted from the main surface while propagating inside. The reflection mirror 21 has a function of reflecting light propagating inside the light guide 20. The prism sheet 22 has a function of changing the traveling direction of the light emitted from the main surface of the light guide 20 to a direction closer to the normal line of the main surface. Since the light source device 1 is the light source device of the first embodiment, the description thereof is omitted.

  The light guide 20 is a plate made of a resin having optical transparency such as acrylic resin. The light guide 20 has a wedge shape in which the thickness gradually decreases from the side closer to the end surface 3 a where the light source device 1 is provided to the side farther from the side. That is, as shown in FIG. 10, the cross-sectional shape of the light guide 20 when cut along a plane (yz plane) perpendicular to the first main surface 20b described later is a right triangle. The end surface 20 a of the light guide 20 is a light incident surface on which light emitted from the light source device 1 is incident. Therefore, the light emission surface 5 a of the cylindrical lens 5 of the light source device 1 faces the end surface 20 a of the light guide 20. The first main surface 20b (upper surface in FIG. 10) of the light guide 20 is a light emission surface that emits light incident on the inside.

  In the present embodiment, the light propagation direction within the first main surface 20b of the light guide 20 is the z-axis direction, the direction orthogonal to the light propagation direction is the x-axis direction, and the first main surface 20b. An orthogonal direction (thickness direction of the light guide 20) is defined as a y-axis direction. Therefore, the “light propagation direction” in the present embodiment means a direction in which light (indicated by an arrow L) propagates while reflecting in the yz section of the light guide 20 as shown in FIG. Rather, it means the direction in which light propagates when viewed from the normal direction of the first main surface 20b of the light guide 20 (shown by the solid arrow Z in FIGS. 10 and 11).

  The second main surface 20c (the lower surface in FIG. 10) facing the first main surface 20b of the light guide 20 is a surface inclined at a constant inclination angle with respect to the first main surface 20b in the light propagation direction. It is. The inclination angle α of the second main surface 20c with respect to the first main surface 20b (the angle between the first main surface 20b and the second main surface 20c, sometimes called the apex angle of the light guide 20) is, for example, 1 °. It is set to about ~ 2 °. The second main surface 20c is provided with a reflecting mirror 21 made of a metal film having a high light reflectance such as aluminum. By providing the reflection mirror 21, the entire second main surface 20 c functions as a reflection surface that reflects light propagating through the light guide 20. The reflection mirror 21 may be formed of a metal film directly formed on the second main surface 20c of the light guide 20, or a structure in which a reflection plate manufactured separately from the light guide 20 is bonded. It is also good.

  The prism sheet 22 is provided at a position facing the light exit surface 20b of the light guide 20 (above the light guide 20 in FIG. 10). In the prism sheet 22, a plurality of prism structures 23 are provided on a surface facing the light exit surface 20 b of the light guide 20. Each prism structure 23 extends in a direction orthogonal to the light propagation direction Z. The prism sheet 22 is disposed so that the surface on which the prism structure 23 is provided faces the light exit surface 20 b of the light guide 20. As shown in FIG. 10, the cross-sectional shape of the prism structure 23 in the cross section cut along the yz plane is a right triangle. The prism structure 23 includes a first surface 23a that is orthogonal to the light exit surface 20b of the light guide 20, and a second surface 23b that forms a predetermined tip angle with respect to the first surface 23a. .

Hereinafter, the operation of the surface light source device 19 configured as described above will be described.
As shown in FIG. 11, when attention is paid to light I0 (y0, θ0) incident at an incident angle θ0 from an arbitrary incident position y0 on the end face 20a of the light guide 20, the incident light I0 (y0, θ0) is By repeating reflection inside the light guide 20, the critical angle condition is broken, and the light is emitted from the interface between the first main surface 20 b of the light guide 20 and air to the outside.

  That is, the light L incident on the light guide 20 is guided while being repeatedly reflected between the first main surface 20b (light emission surface) and the second main surface 20c (reflection surface), as shown in FIG. The light 20 travels in the light propagation direction Z (right side in FIG. 11). Assuming that the first main surface and the second main surface are parallel, the incident angle of the light to the first main surface and the second main surface does not change even if light is repeatedly reflected. However, in the case of the present embodiment, the light guide 20 has a wedge shape in which the thickness gradually decreases with increasing distance from the light incident surface 20a side, and the second main surface 20c has a predetermined inclination angle with respect to the first main surface 20b. Have. Therefore, each time the light L is reflected once by the first main surface 20b and the second main surface 20c, the incident angle on the first main surface 20b and the second main surface 20c becomes small.

  Specifically, for example, when the refractive index of the acrylic resin constituting the light guide 20 is 1.5 and the refractive index of air is 1.0, the first main surface 20b (light emission surface) of the light guide 20 The critical angle, that is, the critical angle at the interface between the acrylic resin constituting the light guide 20 and the air is about 42 ° from Snell's law. When the light immediately after entering the light guide 20 is incident on the first main surface 20b, the critical angle condition is satisfied as long as the incident angle of the light L on the first main surface 20b is larger than the critical angle of 42 °. Therefore, the light L is totally reflected by the first main surface 20b. Thereafter, when the light L is repeatedly reflected between the first main surface 20b and the second main surface 20c, the incident angle of the light L on the first main surface 20b becomes smaller than 42 ° which is a critical angle. The critical angle condition is broken and the light L is emitted to the external space. The light that has reached the second major surface 20c is reflected by the reflecting mirror 21 even if the incident angle becomes smaller than the critical angle.

  That is, the light L is confined inside the light guide 20 while the incident angle on the first main surface 20b is larger than the critical angle, and the incident angle on the first main surface 20b becomes smaller than the critical angle. It is sequentially injected immediately after. Therefore, the emission angles of light emitted from the first main surface 20b are substantially constant. Since the light L is refracted when exiting from the first main surface 20b, the light having an incident angle of about 42 ° to the first main surface 20b is emitted as light having an exit angle that is substantially horizontal. Thus, when viewed in a plane (yz plane) parallel to the light propagation direction Z and perpendicular to the light exit surface 20 b of the light guide 20, the light L becomes x when it enters the light guide 20. Although it has high directivity in the axial direction, it has no directivity in the y-axis direction. However, the light L has a high directivity in the z-axis direction when the light path (traveling direction) is bent and emitted from the first main surface 20b of the light guide 20.

  In the above example, the light L is emitted in a direction that is substantially horizontal. Therefore, using the prism sheet 22, the light L emitted from the light guide 20 is raised in a direction close to the normal direction of the first main surface 20 b of the light guide 20. Specifically, by using the prism sheet 22 having the prism structure 23 with a tip angle of about 40 °, the light L is incident from the first surface 23a of the prism structure 23 and reflected by the second surface 23b. The light guide 20 can be raised in a direction substantially perpendicular to the first main surface 20b.

  In FIG. 11, the emission position z1 of the light L in the z-axis direction on the first main surface 20b of the light guide 20 is determined by the incident position y0, the incident angle θ0, and the apex angle α of the light guide 20. . Therefore, if the vertex angle α of the light guide 20 is determined, the light emission position z1 can be expressed as z1 = g (y0, θ0). At this time, the light I1 (z1, θ1) is emitted from the emission position z1. Note that θ1 is an emission angle. Therefore, if the luminance is to be made uniform on the first main surface 20b (light exit surface) of the light guide 20, the incident angle characteristic needs to be uniform regardless of the incident position y0. In other words, it is necessary that there is no correlation between the incident position y0 and the incident angle θ0.

  However, as described in the first embodiment, there is generally a correlation between an emission position and an emission angle of light emitted from a uniaxial directional light source device having a parallel plate such as a cylindrical lens. As a result, when the illuminance distribution of light emitted from the light guide is viewed along the z-axis direction, the illuminance distribution of the light source device is reflected, and regions with high illuminance and regions with low illuminance appear alternately.

  On the other hand, the surface light source device 19 of the present embodiment includes the light source device 1 of the first embodiment, that is, the light source device 1 including the anisotropic scattering sheet 3 having a strong scattering property in the y-axis direction. Therefore, the illuminance distribution in the y-axis direction of the light emitted from the light source device 1 is made uniform, and the illuminance distribution in the z-axis direction of the light emitted from the light guide 20 is anisotropically scattered, reflecting the illuminance distribution. It is made uniform compared to the case where there is no sheet. On the other hand, since there is no element that disturbs the directivity in the x-axis direction in the light guide 20, the high directivity in the x-axis direction of the light emitted from the light source device 1 is maintained. Thus, according to this embodiment, a surface light source device having excellent biaxial directivity can be realized.

In order to demonstrate the effect of the surface light source device of this embodiment, the inventors compared the illuminance distribution of the emitted light between the surface light source device of this embodiment and the surface light source device of the comparative example using optical simulation. . The results are shown in FIGS. 12 (A) and 12 (B).
In FIGS. 12A and 12B, it is shown that the illuminance is higher as the color of the light exit surface of the light guide is closer to white, and the illuminance is lower as the color is closer to black.

As the simulation conditions, the same simulation conditions as in the first embodiment were used for the light source device. In addition, for the light guide, the apex angle α of the light guide is 1.4 °, the length of the light guide (dimension in the z-axis direction) is 120 mm, and the thickness of the end face side of the light guide is the thickness of the cylindrical lens. 3mm to match

  As a result of the optical simulation, in the light source device of the comparative example, as shown in FIG. 12A, the light emitting surface 104b of the light guide 104 alternately has a high illuminance region and a low illuminance region. I found out. On the other hand, in the light source device of the present embodiment, as shown in FIG. 12B, it is found that the illuminance of the emitted light in the z-axis direction is made more uniform on the light emitting surface 20b of the light guide 20. It was. Further, since the illuminance distribution of the emitted light in the x-axis direction is not substantially changed, it has been found that high directivity in the x-axis direction is maintained.

[First Modification]
Although the example using the light source device of the first embodiment provided with the anisotropic scattering sheet has been described in the above embodiment, the light source device shown in FIG. 13 may be used instead of this configuration.
As shown in FIG. 13, the light source device 26 of the present modification is provided with an uneven structure for generating anisotropic scattering exhibiting strong scattering in the y-axis direction on the end surface 27 a of the light guide 27. . That is, the concavo-convex structure as shown in FIG. 4 is formed in the end surface 27 a itself of the light guide 27. Such a configuration can be realized, for example, by previously imparting a shape in which the concavo-convex structure is inverted to a mold used when producing the light guide 27 and performing injection molding using this mold. It is. According to this configuration, there is no need to use a light source device provided with an anisotropic scattering sheet.

[Third Embodiment]
Hereinafter, a third embodiment of the present invention will be described with reference to FIGS. 14 and 15.
The basic configuration of the surface light source device of this embodiment is the same as that of the second embodiment, and only the configuration of the anisotropic scattering portion is different from that of the second embodiment.
FIG. 14 is an exploded perspective view showing the surface light source device of the present embodiment. FIG. 15 is a cross-sectional view of the surface light source device of this embodiment, and is a cross-sectional view taken along the line AA ′ of FIG.
In FIG. 14 and FIG. 15, the same reference numerals are given to the same components as those used in the second embodiment, and the description will be omitted.

  In the surface light source device 30 of the present embodiment, a lenticular lens 31 as an anisotropic scattering part is provided between the light source part 2 and the light guide 20 as shown in FIGS. The lenticular lens 31 is formed by arranging a plurality of columnar lenses 32 having a curvature in the short direction and not having a curvature in the longitudinal direction perpendicular thereto. The lenticular lens 31 is arranged such that the direction in which the plurality of columnar lenses 32 are arranged is the thickness direction (y-axis direction) of the cylindrical lens 5. That is, the direction in which the columnar lens 32 has a curvature coincides with the thickness direction (y-axis direction) of the cylindrical lens 5. Here, gaps are provided between the cylindrical lens 5 and the lenticular lens 31 and between the lenticular lens 31 and the light guide 20, but all of the cylindrical lens 5, the lenticular lens 31, and the light guide 20 are in contact with each other. You may do it.

  Reflecting plates 33 are provided above and below the lenticular lens 31. The reflection plate 33 may be made of a metal having high light reflectivity, or may be made of a dielectric multilayer film. That is, the light source device 34 of the present embodiment includes the light source unit 2, the lenticular lens 31, and the reflection plate 33.

  In the surface light source device 30 of the present embodiment, the direction in which the columnar lens 32 has a curvature coincides with the thickness direction (y-axis direction) of the cylindrical lens 5. Therefore, the light scattering property of the lenticular lens 31 is high in the thickness direction (y-axis direction) of the cylindrical lens 5 and low in the width direction (x-axis direction) of the cylindrical lens 5. Therefore, the lenticular lens 31 has the same action as the anisotropic scattering sheet 3 of the first and second embodiments. That is, the discrete illuminance distribution of the light emitted from the light source unit 2 by the lenticular lens 31 is improved, and the illuminance can be made uniform. Thereby, the effect similar to 1st Embodiment that the surface light source device excellent in biaxial directivity is realizable is acquired.

  In the case of the present embodiment, since the lenticular lens 31 and the light guide 20 are separated from each other, the light is scattered from the lenticular lens 31 in a highly scattering direction (y-axis direction), particularly toward the outside of the light guide 20. Some of the light may not enter the light guide 20. On the other hand, since the reflecting plate 33 is provided above and below the lenticular lens 31, the light scattered by the lenticular lens 31 can be reflected by the reflecting plate 33 and incident on the light guide 20. As a result, the utilization efficiency of the light emitted from the light source device 34 can be increased. This type of reflector 33 is effective not only in the present embodiment including the lenticular lens 31 but also in the second embodiment including the anisotropic scattering sheet 3.

[First Modification]
In the first and second embodiments, the example of the light source device provided with the wedge-shaped light guide has been described, but the light source device shown in FIG. 16 may be used instead of this configuration.
As shown in FIG. 16, the light guide 38 of the surface light source device 37 of the present modification has a plurality of prism structures 39 formed on the second main surface 38 c facing the first main surface 38 b (light emission surface). ing. Each prism structure 39 extends in a direction (x-axis direction) orthogonal to the light propagation direction Z. The cross-sectional shape of the prism structure 39 in the cross section cut along the yz plane is a right triangle. The prism structure 39 includes a first surface 39a that is orthogonal to the first main surface 38b of the light guide 38, and a second surface 39b that forms a predetermined tip angle with respect to the first surface 39a. Yes. The second surface 39b functions as a reflecting surface that reflects light propagating through the light guide 18.

  That is, the wedge-shaped light guide 20 of the above embodiment has one continuous reflection surface, whereas the light guide 38 of the present modification has a plurality of divided reflection surfaces. Therefore, the light guide 38 of the present modification can also obtain the same operation as the wedge-shaped light guide. Thereby, the light guide 38 can give high directivity in the z-axis direction to the emitted light.

[Second Modification]
In the first and second embodiments, an example of a light source device including a wedge-shaped light guide has been described. However, instead of this configuration, a light source device shown in FIG. 17 may be used.
As shown in FIG. 17, the surface light source device 41 of the present modification includes the light source device 1, a light guide 42, and a reflection mirror 21. The light guide 42 has a configuration in which three layers of a light guide layer 43, a low refractive index layer 44, and a prism layer 45 are laminated. A plurality of prism structures 46 are formed on the upper surface of the light guide layer 43. The prism structure 46 includes a first surface 46a that is orthogonal to the lower surface of the light guide layer 43, and a second surface 46b that forms a predetermined tip angle with respect to the first surface 46a. Similar to the inclined surface of the wedge-shaped light guide, the second surface 46b functions as a reflective surface that reflects light propagating through the light guide layer 43 and changes the incident angle.

  The low refractive index layer 44 is a layer made of a material having a refractive index lower than that of the light guide layer 43. A plurality of prism structures 47 are formed on the lower surface of the prism layer 45. The prism structure 47 includes a first surface 47a that is orthogonal to the upper surface of the prism layer 45, and a second surface 47b that forms a predetermined tip angle with respect to the first surface 47a. In the surface light source device 41 of the present modification, the light emitted from the low refractive index layer 44 and the prism layer 45 rises in a direction perpendicular to the light exit surface of the light guide 42 without using a prism sheet. be able to.

[Fourth Embodiment]
Hereinafter, a fourth embodiment of the present invention will be described with reference to FIG.
In 4th, 5th embodiment, an example of the display apparatus provided with the surface light source device of the said embodiment is shown. The present embodiment is an example of a liquid crystal display device that includes the surface light source device of the second embodiment as a backlight.
FIG. 18 is a cross-sectional view showing the liquid crystal display device of the present embodiment.
18, the same code | symbol is attached | subjected to the same component as drawing used in 2nd Embodiment, and description is abbreviate | omitted.

  As shown in FIG. 18, the liquid crystal display device 68 of the present embodiment includes a backlight 69 (surface light source device) including the surface light source device 19 of the second embodiment, a first polarizing plate 70, a liquid crystal panel 71, A second polarizing plate 72 and a viewing angle widening film 73 are provided. In FIG. 18, the liquid crystal panel 71 is schematically illustrated as a single plate. The observer views the display from the upper side of the liquid crystal display device 68 in FIG. 18 in which the viewing angle widening film 73 is arranged. Therefore, in the following description, the side on which the viewing angle widening film 73 is disposed is referred to as a viewing side, and the side on which the backlight 69 is disposed is referred to as a back side.

  In the liquid crystal display device 68 of the present embodiment, the light emitted from the backlight 69 is modulated by the liquid crystal panel 71, and a predetermined image, character, or the like is displayed by the modulated light. Further, when the light emitted from the liquid crystal panel 71 passes through the viewing angle widening film 73, the angle distribution of the emitted light becomes wider than before entering the viewing angle widening film 73 and the light is widened. Is injected from. Thereby, the observer can visually recognize the display with a wide viewing angle.

  As the liquid crystal panel 71, for example, an active matrix transmissive liquid crystal panel can be used. However, the liquid crystal panel is not limited to the active matrix transmissive liquid crystal panel. For example, a transflective (transmissive / reflective) liquid crystal panel does not include a switching thin film transistor (hereinafter abbreviated as TFT). A simple matrix type liquid crystal panel may be used. Since a well-known general liquid crystal panel can be used as the liquid crystal panel 71, a detailed description of the configuration is omitted.

  A viewing angle widening film 73 is disposed on the viewing side of the liquid crystal display device 68. The viewing angle widening film 73 includes a base material 74, a plurality of light diffusion portions 75 formed on one surface of the base material 74 (a surface opposite to the viewing side), and a black layer 76 formed on one surface of the base material 74. (Light absorption layer). The viewing angle widening film 73 is disposed on the second polarizing plate 72 in such a posture that the side where the light diffusing portion 75 is provided faces the second polarizing plate 72 and the base 74 side faces the viewing side.

  For the base material 74, for example, a base material made of a transparent resin such as a triacetyl cellulose (TAC) film is preferably used. The light diffusing portion 75 is made of an organic material having optical transparency and photosensitivity such as acrylic resin and epoxy resin. The light diffusing unit 75 has a horizontal cross section (xz cross section) having a circular shape, and has a small surface area on the base material 74 side serving as a light emission end face, and an area of a face opposite to the base material 74 serving as a light incident end face. The area of the horizontal cross section gradually increases from the base material 74 side to the side opposite to the base material 74. That is, the light diffusing unit 75 has a so-called reverse tapered frustoconical shape when viewed from the base material 74 side. The light diffusion part 75 is a part that contributes to the transmission of light in the viewing angle widening film 73. That is, the light incident on the light diffusing portion 75 is totally reflected by the tapered side surface of the light diffusing portion 75, guided in a state of being substantially confined inside the light diffusing portion 75, and diffused in all directions. It is injected at.

  The black layer 76 is formed in a region other than the formation region of the plurality of light diffusion portions 75 on the surface of the base material 74 on the side where the light diffusion portions 75 are formed. For example, the black layer 76 is made of an organic material having light absorption and photosensitivity such as a black resist.

  For example, when the image quality of a liquid crystal display device is adjusted with reference to the front direction of the screen, that is, the light transmitted vertically through the liquid crystal panel, the screen is not displayed in a liquid crystal display device using a conventional backlight having no directivity. Color misregistration occurs when viewed from the front direction and when viewed from the oblique direction. On the other hand, in the liquid crystal display device 68 of the present embodiment, the backlight 69 composed of the surface light source device 19 of the second embodiment having high directivity in both the biaxial directions, that is, the x-axis direction and the z-axis direction. Is used. As a result, light is transmitted through only the angle range where the color change is small in the liquid crystal panel 71. Thereafter, since the light is diffused in all directions by the viewing angle widening film 73, the observer can see a high-quality image with little color shift when viewed from any direction.

[Fifth Embodiment]
Hereinafter, a fifth embodiment of the present invention will be described with reference to FIG.
The present embodiment is an example of a fluorescence excitation type liquid crystal display device including the surface light source device of the second embodiment as a backlight.

  As shown in FIG. 19, the liquid crystal display device 78 of the present embodiment includes a backlight 69 (surface light source device) including the surface light source device 19 of the second embodiment, a liquid crystal element 79, and a light emitting element 80. Yes. In the liquid crystal display device 78 of the present embodiment, a red subpixel 81R for displaying with red light, a green subpixel 81G for displaying with green light, and a blue subpixel 81B for displaying with blue light are arranged adjacent to each other. These three sub-pixels 81R, 81G, and 81B constitute one pixel that is a minimum unit that constitutes a display.

  The backlight 69 emits excitation light L1 that excites the phosphor layers 82R, 82G, and 82B of the light emitting element 80. The backlight 69 of the present embodiment emits ultraviolet light or blue light as the excitation light L1. The liquid crystal element 79 modulates the transmittance of the excitation light L1 emitted from the backlight 69 for each of the subpixels 81R, 81G, and 81B. Excitation light L1 modulated by the liquid crystal element 79 is incident on the light emitting element 80, and the phosphor layers 82R, 82G, and 82B are excited and emitted light is emitted to the outside. Accordingly, in the present embodiment, the upper side of the liquid crystal display device 78 shown in FIG. 19 is the viewing side on which the observer views the display.

  The liquid crystal element 79 has a configuration in which a liquid crystal layer 85 is sandwiched between a first transparent substrate 83 and a second transparent substrate 84. In the case of the present embodiment, the second transparent substrate 84 positioned on the front side as viewed from the observer also serves as the substrate of the light emitting element 80. A first transparent electrode 86 is formed for each subpixel on the inner surface (the surface on the liquid crystal layer 85 side) of the first transparent substrate 83, and an alignment film (not shown) is formed so as to cover the first transparent electrode 86. Yes. A first polarizing plate 87 is provided on the outer surface of the first transparent substrate 83 (the surface opposite to the liquid crystal layer 85 side). As the first transparent substrate 83, for example, a substrate that can transmit excitation light made of glass, quartz, plastic, or the like can be used. For the first transparent electrode 86, for example, a transparent conductive material such as indium tin oxide (hereinafter abbreviated as ITO) is used. As the first polarizing plate 87, a conventional general external polarizing plate can be used.

  On the other hand, the phosphor layer 82 and the first light absorption layer 88 are laminated in this order from the substrate side on the inner surface (surface on the liquid crystal layer 85 side) of the second transparent substrate 84. The phosphor material constituting the phosphor layer 82 has a different emission wavelength band for each subpixel. When the excitation light from the backlight 69 is ultraviolet light, the red subpixel 81R is provided with a phosphor layer 82R made of a phosphor material that absorbs ultraviolet light and emits red light. Similarly, the green subpixel 81G is provided with a phosphor layer 82G made of a phosphor material that absorbs ultraviolet light and emits green light. The blue subpixel 81B is provided with a phosphor layer 82B made of a phosphor material that absorbs ultraviolet light and emits blue light.

  Alternatively, when the excitation light from the backlight 69 is blue light, the red subpixel 81R and the green subpixel 81G are made of phosphor materials that absorb blue light and emit red light and green light, respectively. The phosphor layers 82R and 82G are provided. Instead of the phosphor layer, the blue subpixel 81B is provided with a light diffusion layer that diffuses the blue light that is the excitation light without converting the wavelength and emits the light to the outside. Further, a second polarizing plate 89 is formed on the inner surface of the second transparent substrate 84 so as to cover the first light absorption layer 88, and the second transparent electrode 90 and an alignment film (not shown) are formed on the surface of the second polarizing plate 89. ) Are stacked. The second polarizing plate 89 is a polarizing plate made by using a coating technique or the like in the manufacturing process of the liquid crystal element 79, and is a so-called in-cell polarizing plate. As with the first transparent electrode 86, a transparent conductive material such as ITO is used for the second transparent electrode 90.

  A second light absorption layer 91 is formed on the outer surface side of the second transparent substrate 84. The first light absorption layer 88 provided on the inner surface of the second transparent substrate 84 is for suppressing a decrease in contrast due to leakage of the excitation light L <b> 1 from the backlight 69. The 2nd light absorption layer 91 provided in the outer surface of the 2nd transparent substrate 84 is for suppressing the contrast fall by external light.

  As described in the fourth embodiment, an ordinary liquid crystal display device has a color shift when viewed from an oblique direction. On the other hand, the fluorescence excitation type liquid crystal display device 78 of the present embodiment uses a surface light source device that emits ultraviolet light or blue light having high directivity in two axial directions as the backlight 69, and the ultraviolet light or Blue light is color-converted by the phosphor layer 82. At this time, since the light of each color is emitted isotropically from the phosphor layer 82, the observer can see a high-quality image with little color shift when viewed from any direction.

[Configuration example of display device]
Hereinafter, one configuration example of the display device will be described with reference to FIG.
FIG. 20 is a front view illustrating a schematic configuration of a liquid crystal display device which is a configuration example of the display device.

As shown in FIG. 20, the liquid crystal television 93 of this configuration example includes the liquid crystal display device 68 of the fourth embodiment or the liquid crystal display device 78 of the fifth embodiment as a display screen. A liquid crystal panel is disposed on the viewer side (front side in FIG. 20), and a backlight (surface light source device) is disposed on the side opposite to the viewer (back side in FIG. 20).
Since the liquid crystal television 93 of this configuration example includes the liquid crystal display devices 68 and 78 of the above embodiment, the liquid crystal television 93 is capable of high-quality display.

[Sixth Embodiment]
Hereinafter, a sixth embodiment of the present invention will be described with reference to FIG.
In 6th Embodiment, an example of the illuminating device provided with the light source device of 1st Embodiment is shown.
FIG. 21 is a perspective view showing the lighting device of the present embodiment.
In FIG. 21, the same components as those used in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  As shown in FIG. 21, the illuminating device 51 of the present embodiment has a configuration in which three rows of light source units 52 each including the light source device 1 of the first embodiment are arranged. Note that the number of columns of the light source units 52 is not limited to three, and may be one.

  Since the illuminating device 51 of this embodiment is provided with the light source part 52 which consists of the light source device 1 of 1st Embodiment which has the anisotropic scattering sheet 3, it has high directivity in the direction (x-axis direction) where the light source device was located in a line. On the other hand, it has no directivity in the direction orthogonal to it (y-axis direction), and the illuminance is made uniform. As a result, according to the illumination device of the present embodiment, it is possible to uniformly illuminate a wide area in the direction (x-axis direction) that is narrow in the direction in which the light source devices are arranged (x-axis direction).

[Seventh Embodiment]
The seventh embodiment of the present invention will be described below with reference to FIG.
In 7th Embodiment, an example of the illuminating device provided with the surface light source device of 2nd Embodiment is shown.
FIG. 22 is a cross-sectional view showing the lighting device of the present embodiment.
22, the same code | symbol is attached | subjected to the same component as drawing used in 2nd Embodiment, and description is abbreviate | omitted.

  As shown in FIG. 22, the illumination device 55 of the present embodiment includes the surface light source device 19 of the second embodiment. Therefore, the illuminating device 55 of this embodiment has biaxial directivity, and illuminance is made uniform. As a result, according to the illuminating device 55 of the present embodiment, the illumination light can be condensed in a narrow area, and the area can be illuminated uniformly. If the lighting device 55 of the present embodiment is installed near the ceiling of the hall, for example, light with high directivity is emitted downward from the lighting device 55 due to the use of the prism sheet 22. Can be suitably used.

The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in the above embodiment, it has been described that the shape of the concave mirror is a paraboloid. On the other hand, the shape of the concave mirror that can be used in the above embodiment is not necessarily limited to a paraboloid, and may be a conical curved surface as a concept including a paraboloid. A curve indicating the shape of a cross section passing through the apex of the conical curved surface is called a quadratic curve. A quadratic curve is a curve obtained from a cross section obtained by cutting a cone at an arbitrary plane. When the coordinate in the radial direction of the concave mirror is ρ, the coordinate in the central axis direction of the concave mirror is z, and the conic coefficient is k, the quadratic curve can be expressed by the following equations (1) and (2).

  The shape of the quadratic curve changes depending on the value of the conic coefficient k in the equations (1) and (2). The quadratic curve is, for example, a circle when k = 0, an elliptic curve when k = −0.25, a parabola when k = −1, and a hyperbola when k = −2. In the above embodiment, it is possible to use a concave mirror having these quadratic curves as cross-sectional shapes in the xy plane. As described in the first embodiment, the region where the light from the LED reaches may be at least a conical curved surface, and the region where the light from the LED does not reach may be, for example, a flat surface.

  In addition, the shape, number, arrangement, material, and the like of each member constituting the light source device and the surface light source device exemplified in the above embodiment are not limited to the above embodiment, and can be appropriately changed.

  The present invention can be used for various display devices such as a liquid crystal display device, an organic electroluminescence display device, and a plasma display, or a light source device and a surface light source device used in these display devices, or various illumination devices.

  DESCRIPTION OF SYMBOLS 1,10,15,34 ... Light source device, 2 ... Light source part, 3 ... Anisotropic scattering sheet (anisotropic scattering part), 4 ... LED (light emitting element), 5,11 ... Cylindrical lens (convex lens), 6 DESCRIPTION OF SYMBOLS ... Concave mirror, 12 ... Uneven structure, 16 ... Louver (regulation member), 19, 26, 30, 37, 41 ... Surface light source device, 20, 27, 38, 42 ... Light guide, 22 ... Prism sheet (direction change) Member), 31 ... lenticular lens (anisotropic scattering part), 39 ... prism structure, 51, 55 ... illumination device, 68, 78 ... liquid crystal display device (display device), 69 ... backlight (surface light source device) .

Claims (20)

A light source unit that emits light having different directivities in two axial directions orthogonal to each other;
An anisotropic scattering part having different scattering properties in two axial directions perpendicular to each other, and emitting light incident from the light source part as scattered light,
A light source device characterized in that an axial direction in which directivity of light emitted from the light source unit is low and an axial direction in which the anisotropic scattering unit has high scattering property are substantially matched.   2. The light source device according to claim 1, wherein the anisotropic scattering portion includes an anisotropic scattering sheet in which a plurality of uneven shapes are formed aperiodically.   The light source device according to claim 2, wherein the anisotropic scattering sheet is formed by extending a concavo-convex structure in a uniaxial direction.   The light source device according to claim 1, wherein the anisotropic scattering unit includes a lenticular lens in which a plurality of columnar lenses are arranged.   The reflective member which reflects the light inject | emitted from the said anisotropic scattering part was provided in the axial direction with the high scattering property of the said anisotropic scattering part, The any one of Claim 1 thru | or 4 characterized by the above-mentioned. The light source device according to 1.   2. A restricting member for restricting the spread of light emitted from the anisotropic scattering portion in the axial direction having a low scattering property is provided on the light emission side of the anisotropic scattering portion. The light source device according to any one of Items 5 to 5. The light source unit includes a light emitting element, a concave mirror that reflects light emitted from the light emitting element, and a convex lens disposed in a recess of the concave mirror,
The cross-sectional shape when the concave mirror is cut along a predetermined plane has a curved shape having a focal point at least in part, and the focal point is located on the light emitting surface of the light emitting element,
The convex lens has a pair of parallel planes parallel to the predetermined plane;
7. The light from the light emitting element is reflected by the concave mirror after passing through the convex lens, and is emitted from the light exit surface of the convex lens through the convex lens. The light source device according to item.   The light source device according to claim 7, wherein the anisotropic scattering unit is formed of a concavo-convex structure formed on the light exit surface of the convex lens.   The light source device according to claim 7, wherein the light emitting element is a light emitting diode.   The light source device according to claim 7, wherein the curved shape is substantially a parabola.   11. The light source device according to claim 7, wherein the concave mirror is made of a metal film or a dielectric multilayer film. The light source device according to any one of claims 1 to 11,
A surface light source device, comprising: a light guide that makes light emitted from the light source device enter from an end surface and emit light from a main surface while propagating the light inside.   The surface light source device according to claim 12, wherein the anisotropic scattering part is composed of a concavo-convex structure formed on the end face of the light guide.   The surface light source device according to claim 12, wherein the light guide has a reflecting surface that forms a predetermined inclination angle with respect to the main surface in a light propagation direction.   The said light guide is a wedge shape from which the thickness becomes thin toward the side far from the side close | similar to the said end surface, The whole surface facing the said main surface is the said reflective surface, It is characterized by the above-mentioned. Surface light source device.   15. The surface according to claim 14, wherein the light guide has a plurality of prism structures on a surface facing the main surface, and one inclined surface of the prism structure is the reflection surface. Light source device.   The direction change member which changes the advancing direction of the light inject | emitted from the main surface of the said light guide to the direction close | similar to the normal line of the said main surface was provided. The surface light source device according to one item.   18. A display device comprising: the surface light source device according to claim 12; and a display element that performs display using light emitted from the surface light source device.   An illumination device comprising the light source device according to any one of claims 1 to 11.   An illumination device comprising the surface light source device according to any one of claims 12 to 17.