Organic light emitting diode display for suppressing reflection of external light

• US 8,198,802 B2
• Filed: 07/23/2009
• Issued: 06/12/2012
• Est. Priority Date: 07/25/2008
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Mobile Display Company Limited (Samsung Electronics Co. Ltd.)
• Inventors: Park, Soon-Ryong, Jeong, Hee-Seong, Jung, Woo-Suk, Kwak, Noh-Min, Jeong, Chul-Woo, Kim, Eun-Ah, Jeon, Hee-Chul, Lee, Joo-Hwa
• Primary Examiner(s): Green, Tracie Y
• Application Number:
  US12/508,409
• Publication Number:
  US 20100019666A1
• Time in Patent Office: 1,055 Days
• Field of Search: 313498-512, 428690-691, 428/917, 438 26- 29, 438/34, 438/82, 257/40, 257/72, 257 98-100, 257642-643, 257/759, 427/66, 427532-535, 427/539
• US Class Current: 313/504
• CPC Class Codes: G02B 5/3025 Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state G02B5/3008, G02B5/3016 take precedence
• CPC Class Codes: G02B 5/3083 Birefringent or phase retarding elements G02B5/3008, G02B5/3016 take precedence; systems for polarisation control G02B27/286; manufacturing phase modulating patterns by lithographic processes G03F7/001
• CPC Class Codes: H10K 50/86 Arrangements for improving contrast, e.g. preventing reflection of ambient light
• CPC Class Codes: H10K 50/868 Arrangements for polarized light emission H10K50/86 takes precedence
• CPC Class Codes: H10K 59/12 Active-matrix OLED [AMOLED] displays
• CPC Class Codes: H10K 59/8791 Arrangements for improving contrast, e.g. preventing reflection of ambient light
• CPC Class Codes: H10K 59/8793 Arrangements for polarized light emission H10K59/8791 takes precedence

Abstract

An organic light emitting diode (OLED) display is disclosed. In one embodiment, the OLED display includes i) an OLED comprising i) a first electrode, ii) an organic emission layer formed on the first electrode, and iii) a second electrode formed on the organic emission layer, ii) a dual brightness enhancement film (DBEF) formed over the second electrode of the OLED, iii) a first polarizing plate formed on the DBEF, iv) a cholesteric liquid crystal (CLC) layer formed on the first polarizing plate, v) a phase delay plate that is a ¼ wavelength plate formed on the CLC layer and vi) a second polarizing plate formed on the phase delay plate.

Claims

1. An organic light emitting diode (OLED) display comprising:

an OLED comprising i) a first electrode, ii) an organic emission layer formed on the first electrode, and iii) a second electrode formed on the organic emission layer;

a dual brightness enhancement film (DBEF) formed over the second electrode of the OLED;

a first polarizing plate directly contacting the DBEF;

a cholesteric liquid crystal (CLC) layer directly contacting the first polarizing plate, wherein the first polarizing plate is interposed between and contacts the CLC layer and the DBEF;

a phase delay plate formed on the CLC layer, wherein the phase delay plate is a ¼

wavelength plate; and

a second polarizing plate formed on the phase delay plate.

2. The OLED display of claim 1, wherein a polarizing axis of the first polarizing plate and a polarizing axis of the second polarizing plate cross each other.

3. The OLED display of claim 2, wherein the polarizing axis of the first polarizing plate and a polarizing axis of the DBEF are the same.

4. The OLED display of claim 1, wherein the CLC layer is configured to transmit one of right-circularly polarized light and left-circularly polarized light and reflect the other light.

5. The OLED display of claim 1, wherein the phase delay plate is configured to receive first linearly polarized light from the second polarizing plate and output first circularly polarized light toward the CLC layer.

6. The OLED display of claim 5, wherein the CLC layer is configured to transmit the first circularly polarized light toward the first polarizing plate.

7. The OLED display of claim 6, wherein the first polarizing plate is configured to i) transmit a portion of the first circularly polarized light which matches a polarizing axis of the first polarizing plate and ii) absorb a portion of the first circularly polarized light which does not match the polarizing axis of the first polarizing plate.

8. The OLED display of claim 7, wherein the DBEF is configured to receive and transmit, the portion of the first circularly polarized light which matches a polarizing axis of the first polarizing plate, toward the OLED.

9. The OLED display of claim 1, wherein the CLC layer is configured to receive second linearly polarized light from the first polarizing plate and output second circularly polarized light toward the phase delay plate.

10. The OLED display of claim 1, wherein a polarizing axis of the first polarizing plate and a light axis of the CLC layer are the same.

11. The OLED display of claim 1, further comprising an additional phase delay plate disposed between the OLED and the DBEF.

12. The OLED display of claim 11, wherein the additional phase delay plate is a ¼

wavelength plate, and wherein the additional phase plate is configured to change linearly polarizing light received from the DBEF to circularly polarized light.

13. The OLED display of claim 12, further comprising an adhesive layer between the OLED and the additional phase delay plate.

14. An organic light emitting diode display, comprising:

an organic light emitting diode configured to emit at least first circularly polarized light;

a dual brightness enhancement film (DBEF) formed over the OLED and configured to input the first circularly polarized light and output first linearly polarized light;

a first polarizing plate directly contacting the DBEF and configured to transmit the first linearly polarized light;

a cholesteric liquid crystal (CLC) layer directly contacting the first polarizing plate and configured to input the first linearly polarized light and output second circularly polarized light wherein the first polarizing plate is interposed between and contacts the CLC layer and the DBEF;

a first phase delay plate formed on the CLC layer and configured to input the second circularly polarized light and output second linearly polarized light; and

a second polarizing plate formed on the first phase delay plate and configured to transmit the second linearly polarized light.

15. The OLED display of claim 14, wherein the first phase delay plate is a ¼

wavelength plate.

16. The OLED display of claim 14, further comprising a second phase delay plate disposed between the OLED and the DBEF.

17. The OLED display of claim 16, further comprising an adhesive layer between the OLED and the second phase delay plate.

18. The organic light emitting diode display of claim 14, further comprising:

a first substrate;

a driving circuit formed between the first substrate and the organic light emitting diode, wherein the driving circuit is configured to drive the organic light emitting diode; and

a second substrate formed on the second polarizing plate and configured to display images based on the second linearly polarized light received from the second polarizing plate.

19. An organic light emitting diode display, comprising:

a first polarizing plate configured to input external light and output first linearly polarized light;

a first phase delay plate formed below the first polarizing plate and configured to input the first linearly polarized light and output first circularly polarized light;

a cholesteric liquid crystal (CLC) layer formed below the first phase delay plate and configured to transmit the first circularly polarized light;

a second polarizing plate formed below and directly contacting the CLC layer and configured to input the first circularly polarized light and output second linearly polarized light;

a dual brightness enhancement film (DBEF) formed below and directly contacting the second polarizing plate and configured to transmit the second linearly polarized light;

a second phase delay plate formed below the DBEF and configured to input the second linearly polarized light and output second circularly polarized light; and

an organic light emitting diode configured to reflect at least part of the second circularly polarized light toward the second phase delay plate.

20. The OLED display of claim 19, wherein both the first and second phase delay plates are a ¼

wavelength plate.