Optical member, light source apparatus, display apparatus, and terminal apparatus
An optical member including: a Fresnel lens sheet for deflecting and emitting deflected light, A louver for restricting a direction of light rays, where the louver restricts the traveling direction of incident light from the deflecting element to a direction that is parallel to the optical path of the incident light, and emits the restricted light. The Fresnel lens sheet is disposed so that a machined surface thereof faces the louver.
1. A light source apparatus comprising:
a planar light source that emits light in a planar state;
a deflecting element that deflects and emits incident light such that a direction in which the incident light is deflected varies depending on an incident position of the incident light; and
a light-ray direction restricting element that comprises a transmissive area and an absorptive area and is disposed in an optical path of the incident light to restrict a traveling direction of the incident light to a direction that is parallel to the optical path so that the incident light has a high-directivity,
the light source apparatus being configured to focus the light from the planar light source toward a single externally-positioned imaginary point or a single straight line orthogonal to a light-ray restricting direction of the light-ray direction restricting element, wherein
the light-ray direction restricting element has a configuration that a refractive index of the transmissive area is greater than a refractive index of air, whereby an angle between a principal axis direction of the light restricted and emitted by the light-ray direction restricting element and a surface normal line direction of the planar light surface is greater than an angle between a principal axis direction of the incident light into the light-ray direction restricting element and the surface normal line direction.
2. The light source apparatus according to claim 1 , wherein
the light source apparatus is configured to focus light toward the single straight line orthogonal to the light-ray restricting direction of the light-ray direction restricting element,
the deflecting element comprises a Fresnel lens sheet that one-dimensionally focuses the incident light, and
a direction of a transmission/absorption boundary surface between the transmissive area and the absorptive area in the light-ray-direction restricting element is parallel to an optical path of the light focused by the Fresnel lens sheet.
3. The light source apparatus according to claim 1 , wherein
the light source apparatus is configured to focus light toward the single straight line orthogonal to the light-ray restricting direction of the light-ray direction restricting element,
the planar light source is a diffusive planar light source that diffuses light in a plane direction,
the deflecting element comprises a prism sheet that has a plurality of triangular prisms arranged in a direction orthogonal to the straight line and having a ridgeline that extends in a direction parallel to the straight line, and
an angle between a side surface on a far side from the straight line in each of the plurality of prisms and a plane surface orthogonal to the optical path increases with an increase in a distance from the straight line.
4. The light source apparatus according to claim 1 , wherein
the light source apparatus is configured to focus light toward the single externally-positioned imaginary point,
the planar light source is a diffusive planar light source that diffuses light in a plane direction,
the deflecting element comprises a prism sheet that has a plurality of prisms having a trigonal-pyramid shape or a conical shape, the plurality of prisms being two-dimensionally arranged in two directions that intersect said optical path, and
an angle between a side surface on a far side from a point in each of the plurality of prisms and a plane orthogonal to the optical path increases with an increase in a distance from the point.
5. The light source apparatus according to claim 1 , wherein
the light source apparatus is configured to focus light toward the single externally-positioned imaginary point,
the deflecting element comprises a Fresnel lens sheet that has a concentric lens shape and focuses light two-dimensionally toward a focus point in a planar direction of the planar light source, and
a direction of a transmission/absorption boundary surface of the transmissive area and the absorptive area in the light-ray direction restricting element is configured to concentrically match an optical path of the light focused by the Fresnel lens sheet.
6. The light source apparatus according to claim 1 , wherein
the light source apparatus is configured to focus light toward the single externally-positioned imaginary point,
the light-ray direction restricting element is configured by a stack of two louvers, the louvers each comprising transmissive areas and absorptive areas alternately arranged in a one-dimensional direction, and
the transmissive areas and the absorptive areas of the louvers are arranged orthogonal to each other.
7. The light source apparatus according to claim 1 , wherein
the light source apparatus is configured to focus light toward the single externally-positioned imaginary point, and
the light-ray direction restricting element comprises a louver in which transmissive areas and absorptive areas are concentrically and alternately arranged.
8. The light source apparatus according to claim 1 ,
wherein the light-ray direction restricting element further comprises a transparent/scattering switching element capable of switching between a transparent state for transmitting light emitted from the light-ray direction restricting element and a scattering state for scattering the light emitted from the light-ray direction restricting element.
9. A display apparatus comprising:
a planar light source that emits light in a planar state;
a deflecting element that deflects and emits incident light such that a direction in which the incident light is deflected varies depending on an incident position of the incident light;
a light-ray direction restricting element that comprises a transmissive area and an absorptive area and is disposed in an optical path of the incident light to restrict a traveling direction of the incident light to a direction that is parallel to the optical path so that the incident light has a high-directivity;
a light source apparatus configured to focus the light from the planar light source toward a single externally-positioned imaginary point or a single straight line orthogonal to a light-ray restricting direction of the light-ray direction restricting element;
a display panel that transmits light emitted from the light source apparatus to thereby add an image to the light;
the light-ray direction restricting element has a configuration that a refractive index of the transmission area is greater than a refractive index of air, whereby an angle between a principal direction of light restricted and emitted by the light-ray direction restricting element and a surface normal line direction of the planar light surface is greater than an angle between a principal axis direction of the incident light into the light-ray direction restriction element and the surface normal line direction.
10. A terminal apparatus comprising the display apparatus according to claim 9 .
11. The terminal apparatus according to claim 10 , wherein
the terminal apparatus is a television receiver, desktop personal computer, notebook computer, ATM, automatic vending machine, onboard television receiver, PDA, game machine, digital video camera, digital camera, video player, or mobile phone.