Liquid crystal display with mirror mode having top reflective polarizer

• US 7,057,681 B2
• Filed: 06/24/2003
• Issued: 06/06/2006
• Est. Priority Date: 06/24/2002
• Status: Expired due to Term

• Current Assignee: BOE Technology Group Co., Ltd.
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Maeda, Tsuyoshi, Hinata, Shoji
• Primary Examiner(s): Schechter, Andrew
• Assistant Examiner(s): Vu, Phu
• Application Number:
  US10/603,057
• Publication Number:
  US 20040051827A1
• Time in Patent Office: 1,078 Days
• Field of Search: 349 96- 98, 349/67, 349113-114, 349/123
• US Class Current: 349/96
• CPC Class Codes: G02F 1/133528 Polarisers
• CPC Class Codes: G02F 1/133545 Dielectric stack polarisers
• CPC Class Codes: G02F 1/133562 on the viewer side
• CPC Class Codes: G02F 1/133626 providing two modes of illumination, e.g. day-night
• CPC Class Codes: G02F 2203/02 reflective
• CPC Class Codes: G09F 13/12 using a transparent mirror or other light reflecting surface transparent to transmitted light whereby a sign, symbol, picture or other is visible only when illuminated
• CPC Class Codes: H04M 1/0202 Portable telephone sets, e.g. cordless phones, mobile phones or bar type handsets constructional features of telephone transmitters or receivers, e.g. of speakers or microphones H04M1/03
• CPC Class Codes: H04M 1/0266 for a display module assembly

Abstract

In a display device 100, a reflective polarizer 110, a polarizer 120, a retarder 130, a liquid crystal panel 140, a polarizer 150, and a backlight 160 are disposed sequentially from the viewing side. When the liquid crystal panel 140 is set in a light blocking state or the backlight 160 is set in an unlit state, the reflection of an outside light “O” turns the display screen into a mirror state. When the backlight 160 is set in a lit state to drive the liquid crystal panel 140, a transmitted light “T” allows a particular display screen to be visually recognized.

Claims

1. A display device comprising:

a display unit including;

a first polarized light selecting unit on a viewing side thereof, the first polarized light selecting unit transmitting a first polarized light and reflecting a second polarized light having a polarization axis crossing a polarization axis of the first polarized light;

a transmitting polarization axis varying unit;

a second polarized light selecting unit disposed between the first polarized light selecting unit and the transmitting polarization axis varying unit, the second polarized light selecting unit transmitting the first polarized light and absorbing the second polarized light; and

a third polarized light selecting unit disposed on a backside of the transmitting polarization axis varying unit, the third polarized light selecting unit transmits a third polarized light and absorbs a fourth polarized light having a polarization axis crossing a polarization axis of the third polarized light;

wherein no other transmitting polarization axis varying unit is disposed on the viewing side of the first polarized light selecting unit.

2. The display device according to claim 1, wherein a control unit stops light emission from the display unit in a mirror mode.

21. An electronic device comprising the display device according to claim 1.

3. A display device having a transmitting polarization axis varying unit, the display device including:

a first polarized light selecting unit disposed on a viewing side of the transmitting polarization axis varying unit; and

a second polarized light selecting unit disposed on a backside of the transmitting polarization axis varying unit,

wherein the first polarized light selecting unit transmits a first polarized light and reflects a second polarized light having a polarization axis crossing a polarization axis of the first polarized light,

the second polarized light selecting unit transmits a third polarized light and one of absorbs and reflects a fourth polarized light having a polarization axis crossing a polarization axis of the third polarized light, and

the transmitting polarization axis varying unit converts at least a part of the third polarized light to the first polarized light;

wherein a third polarized light selecting unit adapted to transmit the first polarized light and to absorb the second polarized light is disposed between the first polarized light selecting unit and the transmitting polarization axis varying unit;

wherein no other transmitting polarization axis varying unit is disposed on the viewing side of the first polarized light selecting unit.

4. The display device according to claim 3 comprising:

a lighting device on the backside of the second polarized light selecting unit,

wherein the second polarized light selecting unit transmits the third polarized light and absorbs the fourth polarized light,

a fourth polarized light selecting unit disposed between the second polarized light selecting unit and the lighting device, and

the fourth polarized light selecting unit transmits the third polarized light and reflects the fourth polarized light.

5. The display device according to claim 3, wherein the second polarized light selecting unit transmits the third polarized light and reflects the fourth polarized light.

6. The display device according to claim 3, wherein a surface on the viewing side of the polarized light selecting unit is flat.

7. The display device according to claim 3, wherein a transparent protective film is formed on a surface on the viewing side of the first polarized light selecting unit.

8. The display device according to claim 3, wherein a lighting unit adapted to emit light to the viewing side is disposed on the backside of the second polarized light selecting unit.

9. The display device according to claim 8, wherein no light reflection component for reflecting outside light to the viewing side in a form supporting display is disposed between the first polarized light selecting unit and the lighting unit.

10. The display device according to claim 8, wherein the transmitting polarization axis varying unit does not emit the first polarized light when the lighting unit is off.

11. The display device according to claim 3, wherein a polarized light selecting area of the first polarized light selecting unit extends beyond an area overlapping a transmitting polarization axis varying area of the transmitting polarization axis varying unit.

12. The display device according to claim 8, wherein a light amount emitted in a normal direction is greatest in an emission angle distribution of luminous light of the lighting unit.

13. The display device according to claim 12, wherein the luminous light of the lighting unit is mainly distributed at an emission angle ranging from zero (0) to forty (40) degrees.

14. The display device according to claim 12, wherein the luminous light of the lighting unit is one fiftieth ( 1/50) or below of a light amount in the normal direction for a range exceeding an emission angle of forty five (45) degrees.

15. The display device according to claim 3, wherein a color filter is disposed on the backside of the first polarized light selecting unit.

16. The display device according to claim 3, wherein a retarder is disposed between the first polarized light selecting unit and the transmitting polarization axis varying unit.

17. The display device according to claim 3, wherein a transparent member is disposed on the viewing side of the first polarized light selecting unit, and the first polarized light selecting unit is directly or indirectly disposed adjacent the transparent member.

18. The display device according to claim 17, wherein the first polarized light selecting unit is bonded to the transparent member by a transparent substance.

19. The display device according to claim 17, wherein a surface of the transparent member on the first polarized light selecting unit is flat.

20. The display device according to claim 17, wherein a surface on the viewing side of the transparent member is curved.

22. An electronic device comprising:

the display device according to claim 3; and

a display drive unit adapted to drive the transmitting polarization axis varying unit.

23. An electronic device comprising:

the display device according to claim 8;

display drive unit adapted to drive the transmitting polarization axis varying unit; and

a lighting control unit adapted to control the lighting unit.

24. An electronic device comprising:

a display unit that includes;

a first polarized light selecting unit adapted to transmit a first polarized light and to reflect a second polarized light having a polarization axis crossing a polarization axis of the first polarized light on a viewing side thereof;

a transmitting polarization axis varying unit; and

a second polarized light selecting unit disposed between the first polarized light selecting unit and the transmitting polarization axis varying unit, the second polarized light selecting unit transmitting the first polarized light and absorbing the second polarized light; and

a third polarized light selecting unit disposed on a backside of the transmitting polarization axis varying unit, the third polarized light selecting unit transmits a third polarized light and one of absorbs and reflects a fourth polarized light having a polarization axis crossing a polarization axis of the third polarized light;

wherein the transmitting polarization axis varying unit converts at least a part of the third polarized light to the first polarized light; and

wherein no other transmitting polarization axis varying unit is disposed on the viewing side of the first polarized light selecting unit.

25. The electronic device according to claim 24 further comprising an input part for allowing an operation of the display device or for allowing data input to display in the display device,

wherein the input part is operated to allow switching between a transmissive display mode and a mirror mode.

26. A display device comprising:

an electro-optical panel;

a first polarizer on one side of the electro-optical panel that one of reflects and absorbs light;

a reflective polarizer on the other side of the electro-optical panel; and

a second polarizer disposed between the reflective polarizer and the electro-optical panel that absorbs light;

wherein the reflective polarizer transmits a first polarized light and reflects a second polarized light that has a polarization axis that crosses a polarization axis of the first polarized light;

the second polarizer transmits the first polarized light and absorbs the second polarized light;

the first polarizer transmits a third polarized light and one of absorbs and reflects a fourth polarized light having a polarization axis crossing a polarization axis of the third polarized light; and

the electro-optic panel converts at least a part of the third polarized light to the first polarized light;

wherein no other electro-optical panel is disposed on the viewing side of the reflective polarizer.

27. The display device according to claim 26, further comprising a retarder disposed between the second polarizer and the electro-optical panel.

28. The display device according to claim 26, further comprising a retarder disposed between the reflective polarizer and the electro-optical panel.

29. The display device according to claim 26, further comprising a reflective polarizer disposed farther from the electro-optical panel than the first absorptive polarizer.

30. The display device according to claim 26, further comprising a light source disposed farther from the electro-optical panel than the first polarizer.

31. The display device according to claim 26, wherein the reflective polarizer is the outermost polarizer at the side of the electro-optical panel to which the second polarizer and the reflective polarizer are disposed.

32. A display device comprising:

a transmitting polarization axis varying unit;

a first polarized light selecting unit on a viewing side of the transmitting polarization axis varying unit, the first polarized light selecting unit transmitting a first polarized light and reflecting a second polarized light having a polarization axis crossing a polarization axis of the first polarized light;

a second polarized light selecting unit disposed on a backside of the transmitting polarization axis varying unit, the second polarized light selecting unit transmits a third polarized light and absorbs a fourth polarized light having a polarization axis crossing a polarization axis of the third polarized light; and

a lighting unit disposed on a backside of the second polarized light selecting unit, the lighting unit emitting light to the viewing side;

wherein the transmitting polarization axis varying unit converts at least a part of the third polarized light to the first polarized light;

the display device switches between a display mode, in which a display light is emitted from the transmitting polarization axis varying unit, and a mirror mode, in which the lighting unit is set in an off state or/and the transmitting polarization axis varying unit is set in a light blocking state; and

no other transmitting polarization axis varying unit is disposed on the viewing side of the first polarized light selecting unit.

33. The display device according to claim 32, wherein the transmitting polarization axis varying unit is a liquid crystal display.

34. A display device comprising:

a transmitting polarization axis varying unit;

a first polarized light selecting unit on a viewing side of a transmitting polarization axis varying unit, the first polarized light selecting unit transmitting a first polarized light and reflecting a second polarized light having a polarization axis crossing a polarization axis of the first polarized light;

a second polarized light selecting unit disposed on a backside of the transmitting polarization axis varying unit, the second polarized light selecting unit transmits a third polarized light and one of absorbs and or reflects a fourth polarized light having a polarization axis crossing a polarization axis of the third polarized light;

a third polarized light selecting unit disposed between the first polarized light selecting unit and the transmitting polarization axis varying unit, the third polarized light selecting unit transmits the first polarized light and absorbs the second polarized light; and

a lighting unit disposed on a backside of the second polarized light selecting unit, the lighting unit emitting light to the viewing side;

wherein the transmitting polarization axis varying unit converts at least a part of the third polarized light to the first polarized light;

the display device switches between a display mode, in which a display light is emitted from the transmitting polarization axis varying unit, and a mirror mode, in which the lighting unit is set in an off state;

wherein an emission angle distribution of luminous light of the lighting unit in the display mode includes a greatest light amount emitting in a direction orthogonal to the display screen; and

wherein no other transmitting polarization axis varying unit is disposed on the viewing side of the first polarized light selecting unit.