Light emitting element and image display apparatus using the light emitting element

• US 8,643,050 B2
• Filed: 10/06/2010
• Issued: 02/04/2014
• Est. Priority Date: 10/22/2009
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Katayama, Ryuichi
• Primary Examiner(s): Tran, Long K
• Assistant Examiner(s): Tran, Dzung
• Application Number:
  US13/503,284
• Publication Number:
  US 20120217529A1
• Time in Patent Office: 1,217 Days
• Field of Search: 257/778, 257/98, 349/96, 349/114
• US Class Current: 257/98
• CPC Class Codes: G02B 27/102 for generating a colour image from monochromatic image signal sources
• CPC Class Codes: G02B 27/283 used for beam splitting or combining
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 33/44 characterised by the coatings, e.g. passivation layer or anti-reflective coating
• CPC Class Codes: H01L 33/46 Reflective coating, e.g. dielectric Bragg reflector

Abstract

A light emitting element which can emit light in a uniform polarization state at a high efficiency and a higher luminance level is realized. The light emitting element of the present invention is a light emitting element including an active layer for generating light, the light emitting element including: a polarizer layer including a first region that transmits polarized light in a first direction and reflects other light from among the light generated at the active layer, and a second region that transmits polarized light in a second direction orthogonal to the first direction and reflects other light; a wave plate layer including a third region and a fourth region that allow the lights exited from the first region and the second region to enter, and to exit as light in the same polarization state; and a reflection layer that reflects the lights reflected at the first region and the second region.

Claims

1. A light emitting element including an active layer for generating light, the light emitting element comprising:

a polarizer layer including a first region that transmits polarized light in a first direction and reflects other light from among the light generated at the active layer, and a second region that transmits polarized light in a second direction orthogonal to the first direction and reflects other light from among light generated at the active layer;

a wave plate layer including a third region and a fourth region that allows the lights exited from the first region and the second region to enter, and to exit as light in a same polarization state; and

a reflection layer that reflects the lights reflected at the first region and the second region.

2. The light emitting element according to claim 1, wherein

the first region and the second region, and the third region and the fourth region are adjacently arranged in a striped pattern.

3. The light emitting element according to claim 1, wherein

the first region and the second region, and the third region and the fourth region are adjacently arranged in a staggered pattern.

4. The light emitting element according to claim 1, wherein

the third region and the fourth region allow an incident light to exit after respectively giving a different polarization rotation angle thereto.

5. The light emitting element according to claim 4, wherein

the fourth region allows incident light to exit after adding a polarization rotation angle of 90 degrees to the polarization rotation angle of the incident light which is given thereto at the third region.

6. The light emitting element according to claim 1, wherein

the third region and the fourth region respectively give a different phase difference to two orthogonal polarization components of the incident light and allow the same to exit as circularly polarized light.

7. The light emitting element according to claim 1, wherein

when letting P be a sum of widths of the first region and the second region, L1 be the distance between a center in thickness direction of the polarizer layer and a center in thickness direction of the reflection layer, and L2 be the distance from a center in thickness direction of the active layer to the center of the polarizer layer,

P/(2L1+L2) is within the range 0.9 to 6.5.

8. The light emitting element according to claim 7, wherein

P/(2L1+L2) is within the range 1.2 to 4.5.

9. The light emitting element according to claim 7, wherein

P/(2L1+L2) is 2.3.

10. A image display apparatus is provided that uses the light emitting element according to claim 1.