Optical path converting optical element, optical path converter, and optical projector and image display apparatus using said optical element

• US 6,276,803 B1
• Filed: 05/14/1997
• Issued: 08/21/2001
• Est. Priority Date: 05/14/1996
• Status: Expired due to Fees

• Current Assignee: Omron Corporation
• Original Assignee: Omron Corporation
• Inventors: Yamashita, Tsukasa, Kitajima, Hiroshi, Aoyama, Shigeru, Shinohara, Masayuki
• Primary Examiner(s): DOWLING, WILLIAM C
• Application Number:
  US08/856,080
• Time in Patent Office: 1,560 Days
• Field of Search: 353/38, 353/81, 349/57, 349/62, 359/625, 359/640, 359/833, 359/837, 362/339, 362/337
• US Class Current: 353/81
• CPC Class Codes: G02B 27/09 Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for adapting the beam shape of a laser diode G02B19/0052; adapting the beam shape of an LED G02B19/0061; coupling into light guides using intermediate optical elements G02B6/4204; beam shaping specially adapted for lasers H01S3/005
• CPC Class Codes: G02B 27/0927 Systems for changing the beam intensity distribution, e.g. Gaussian to top-hat
• CPC Class Codes: G02B 27/0972 Prisms prisms per se G02B5/04
• CPC Class Codes: G02B 5/045 Prism arrays
• CPC Class Codes: G03B 21/208 Homogenising, shaping of the illumination light
• CPC Class Codes: G03F 7/70058 Mask illumination systems
• CPC Class Codes: H04N 5/7416 involving the use of a spatial light modulator, e.g. a light valve, controlled by a video signal
• CPC Class Codes: H04N 5/7441 the modulator being an array of liquid crystal cells

Abstract

A first prism array (34) formed on a prism array plate (32) is arranged so as to confront a second prism array (37) formed on a prism array plate (35). When a light ray (r) that is parallel to an optical axis is transmitted through the first prism array, the light ray r enters into the second prism array (37) while refracted. The light ray that has been refracted by the second prism array (37) becomes an original light ray (r) that is parallel to the optical axis. Therefore, the light ray (r) that has passed through an optical path converting optical element (31) becomes a light ray (r) that is shifted in a direction perpendicular to the optical axis. As a result, the light is split and shuffled by the first prism array (34), so that a luminous intensity distribution thereof is uniformed.

Claims

1. An image display apparatus comprising a light source, an optical path converting optical element comprising two prism arrays, each prism array having a plurality of prisms arrayed in a prism arraying direction, both prism arrays being disposed in such a manner that the prism arraying directions of the prism arrays are substantially parallel to each other, wherein a surface of at least one prism array is flattened with a material having a refractive index different from a refractive index of a material of which the prism array is formed, and an image display panel.

2. An image display apparatus according to claim 1, further comprising a projecting optical system for forming an image on the image display penal onto a screen.

3. An optical path converting optical element comprising two prism arrays, each prism array having a plurality of prisms arrayed in a prism arraying direction, both prism arrays being disposed in such a manner that the prism arraying directions of the prism arrays are substantially parallel to each other,

wherein the two prism arrays are formed respectively on front and back surfaces of a plate, and

wherein a shape of a prism array disposed on a light entering side and a refractive index of the plate are set in such a manner that a light ray whose optical path has been converted by the prism array disposed on the light entering side is totally reflected on a side surface of the plate.

4. An optical path converting optical element comprising two prism arrays, each prism array having a plurality of prisms arrayed in a prism arraying direction, both prism arrays being disposed in such a manner that the prism arraying directions of the prism arrays are substantially parallel to each other, wherein one of the prism arrays is constructed of an interface between a first portion having a first refractive index and a second portion having a second refractive index;

and the other prism array is constructed of a surface of the second portion.

5. An optical path converting optical element according to claim 4, wherein a shape of a prism array disposed on a light entering side and a refractive index of second portion are set in such a manner that a light ray whose optical path has been converted by the prism array disposed on the light entering side is totally reflected on a side surface of the second portion.

6. An optical path converting optical element comprising two prism arrays, each prism array having a plurality of prisms arrayed in a prism arraying direction, both prism arrays being disposed in such a manner that the prism arraying directions of the prism arrays are substantially parallel to each other, and two plates, each plate having one surface thereof being flat and the other surface being formed into the prism array, a flat surface side of one of the plates being arranged so as to confront a prism array side of the other plate, a prism angle of a prism array disposed on a light entering side ranging from 35 to 45°

, a prism angle of a prism array disposed on a light emerging side ranging from 60 to 70°

.

7. An optical projector comprising a light source and an optical path converting optical element comprising two prism arrays, each prism array having a plurality of prisms arrayed in a prism arraying direction, both prism arrays being disposed in such a manner that the prism arraying directions of the prism arrays are substantially parallel to each other, wherein a surface of at least one prism array is flattened with a material having a refractive index different from a refractive index of a material of which the prism array is formed.

8. An optical path converting optical element comprising two prism arrays, each prism array having a plurality of prisms arrayed in a prism arraying direction, both prism arrays being disposed in such a manner that the prism arraying directions of the prism arrays are substantially parallel to each other, wherein a surface of at least one prism array is flattened with a material having a refractive index different from a refractive index of a material of which the prism array is formed.

9. An optical path converting optical element comprising two prism arrays, each prism array having a plurality of prisms arrayed in a prism arraying direction, both prism arrays being disposed in such a manner that the prism arraying directions of the prism arrays are substantially parallel to each other, wherein a light reflecting surface is formed between a first prism array and a second prism array in such a manner that an outer circumference of both prism arrays is enclosed.

10. An optical path converting optical element comprising two prism arrays, each prism array having a plurality of prisms arrayed in a prism arraying direction, both prism arrays being disposed in such a manner that the prism arraying directions of the prism arrays are substantially parallel to each other, wherein a light shifting amount is equal to about ¼

an effective area of an incident light flux.

11. An optical path converting optical element comprising two prism arrays, each prism array having a plurality of prisms arrayed in a prism arraying direction, both prism arrays being disposed in such a manner that the prism arraying directions of the prism arrays are substantially parallel to each other, wherein a light shifting amount is equal to about ⅛

an effective area of an incident luminous flux.

12. An optical projector comprising a light source and an optical path converting optical element comprising two prism arrays, each prism array having a plurality of prisms arrayed in a prism arraying direction, both prism arrays being disposed in such a manner that the prism arraying directions of the prism arrays are substantially parallel to each other, wherein the two prism arrays are formed respectively on front and back surfaces of a plate, and wherein a shape of a prism array disposed on a light entering side and a refractive index of the plate are set in such a manner that a light ray whose optical path has been converted by the prism array disposed on the light entering side is totally reflected on a side surface of the plate.

13. An optical path converter, comprising:

a first optical path converting optical element comprising two prism arrays, each prism array having a plurality of prisms arrayed in a prism arraying direction, both prism arrays being disposed in such a manner that the prism arraying directions of the prism arrays are substantially parallel to each other, wherein a surface of at least one prism array is flattened with a material having a refractive index different from a refractive index of a material of which the prism array is formed, said first optical path converting optical element arranged on a light entering side; and

a second optical path converting optical element comprising two prism arrays, each prism array having a plurality of prisms arrayed in a prism arraying direction, both prism arrays being disposed in such a manner that the prism arraying directions of the prism arrays are substantially parallel to each other, wherein a light reflecting surface is formed between a first prism array and a second prism array in such a manner that an outer circumference of both prism arrays is enclosed, said second optical path converting optical element arranged on a light emerging side.

14. An image display apparatus comprising a light source, an optical path converting optical element comprising two prism arrays, each prism array having a plurality of prisms arrayed in a prism arraying direction, both prism arrays being disposed in such a manner that the prism arraying directions of the prism arrays are substantially parallel to each other, wherein the two prism arrays are formed respectively on front and back surfaces of a plate, and wherein a shape of a prism array disposed on a light entering side and a refractive index of the plate are set in such a manner that a light ray whose optical path has been converted by the prism array disposed on the light entering side is totally reflected on a side surface of the plate, and an image display panel.

15. An image display apparatus according to claim 14, further comprising a projecting optical system for image on the image display panel a screen.