Illuminator using a combination of pseudo-white LED and lens sheet

1. An illuminator comprising:

a light source that radially emits white lights in a forward direction; and

a lens sheet that is arranged facing the light source and that has a plurality of prisms on one side thereof concentrically at an optical axis so as to control orientation of the white lights that are emitted from the light source,

wherein the light source is composed of: a luminous element that emits lights with a predetermined wavelength; and a sealing body that covers the luminous element and that includes phosphors therewith, the phosphors being adapted to receive the lights with the predetermined wavelength which are emitted from the luminous element so as to emit fluorescence, and

the lens sheet includes prisms that have focal distances each different from the prisms adjacent thereto.

2. The illuminator according to claim 1 , wherein the lens sheet includes an area in which a focal distance of the plurality of prisms is changed according to a distance from the optical axis.

3. The illuminator according to claim 2 , wherein the plurality of prisms include:

a plurality of refraction prisms that are formed at an area placed on a side of the optical axis, the refraction prisms having a refractive function; and

a plurality of reflection prisms that are formed outside the area in which the refraction prisms are formed, the reflection prisms having a reflective function, wherein

the plurality of refraction prisms are formed as that the more apart the refraction prisms become from the optical axis, the longer the focal distance thereof becomes relative to a distance between the light source and the lens sheet, and

the plurality of the reflection prisms are formed as that the closer the reflection prisms become to the optical axis, the longer the focal distance thereof becomes relative to the distance between the light source and the lens sheet.

4. The illuminator according to claim 3 , wherein the lens sheet has a flat surface thereon, the flat surface being placed between each of the plurality of prisms that is adjacent to each other.

5. The illuminator according to claim 4 , wherein the lens sheet has a flat surface thereon, the flat surface being placed between each of the plurality of prisms that is adjacent to each other.

6. The illuminator according to claim 2 , wherein the lens sheet has a flat surface thereon, the flat surface being placed between each of the plurality of prisms that is adjacent to each other.

7. The illuminator according to claim 6 , wherein the lens sheet has a flat surface thereon, the flat surface being placed between each of the plurality of prisms that is adjacent to each other.

8. The illuminator according to claim 2 , wherein the light source is composed of: a blue light-emitting diode that emits a blue-series light; and a phosphor that receives the blue-series light and converts the blue-series light into a yellow-series light.

9. The illuminator according to claim 3 , wherein the light source is composed of: a blue light-emitting diode that emits a blue-series light; and a phosphor that receives the blue-series light and converts the blue-series light into a yellow-series light.

10. The illuminator according to claim 1 , wherein the lens sheet has a flat surface thereon, the flat surface being placed between each of the plurality of prisms that is adjacent to each other.

11. The illuminator according to claim 10 , wherein the light source is composed of: a blue light-emitting diode that emits a blue-series light; and a phosphor that receives the blue-series light and converts the blue-series light into a yellow-series light.

12. The illuminator according to claim 1 , wherein the light source is composed of: a blue light-emitting diode that emits a blue-series light; and a phosphor that receives the blue-series light and converts the blue-series light into a yellow-series light.