Display device and electronic apparatus using the same

• US 6,507,380 B1
• Filed: 03/25/1999
• Issued: 01/14/2003
• Est. Priority Date: 07/25/1997
• Status: Expired due to Term

• Current Assignee: BOE Technology Group Co., Ltd.
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Iijima, Chiyoaki
• Primary Examiner(s): TON, MINH TOAN T
• Application Number:
  US09/269,538
• Time in Patent Office: 1,391 Days
• Field of Search: 349/97, 349/98, 349/96, 349/115, 349/64, 349/9, 349/112
• US Class Current: 349/96
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/133545 Dielectric stack polarisers
• CPC Class Codes: G02F 1/13362 providing polarized light, e.g. by converting a polarisation component into another one
• CPC Class Codes: G02F 1/133626 providing two modes of illumination, e.g. day-night
• CPC Class Codes: G02F 1/1347 Arrangement of liquid crystal layers or cells in which the final condition of one light beam is achieved by the addition of the effects of two or more layers or cells
• CPC Class Codes: G09G 2310/06 Details of flat display driving waveforms
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence
• CPC Class Codes: G09G 3/367 with a nonlinear element in series with the liquid crystal cell, e.g. a diode, or M.I.M. element

Abstract

A polarizer 130 is provided on the upper side of a TN liquid crystal 140, and a light scattering layer 150, a polarization separator 160, a polarizer 170 and a light source 190 are provided on the lower side of the TN element 140. The polarized light separator 160 causes a linear polarized light component in the direction of a transmission axis of light incident from above to be transmitted, and reflects a linear polarized light component thereof in the direction of a reflection axis orthogonal thereto. Under external light, it becomes white in a voltage non-application portion 120, and it becomes dark in a voltage application portion 110. Under light source light, it becomes dark in the voltage non-application portion 120, and it becomes light in the voltage application portion 110. The polarized light separator 160 and the polarizer 170 are arranged such that the transmission axis of the polarized light separator 160 is deviated from the transmission axis of the polarizer 170 by a predetermined angle θ and deviated from the absorption axis of the polarizer 170 by a predetermined angle θ′.

Claims

1. A display device comprising:

variable transmission polarization axis means capable of varying a transmission polarization axis;

first polarized light separating means which is arranged on one side of the variable transmission polarization axis means and which allows light that is a linear polarized light component in a first direction to be transmitted and reflects or absorbs light that is a linear polarized light component in a predetermined direction different from the first direction;

second polarized light separating means which is arranged on another side of the variable transmission polarization axis means and which allows light that is a linear polarized light component in a second direction to be transmitted and reflects light that is a linear polarized light component in a predetermined direction different from the second direction;

a polarizer arranged on an opposite side of the variable transmission polarization axis means with respect to the second polarized light separating means; and

a light source which is arranged on an opposite side of the second polarized light separating means with respect to the polarizer and which applies light to the variable transmission polarization axis means side,

wherein a positional relationship between the second polarized light separating means and the polarizer is determined such that the second direction is deviated by a predetermined angle θ

(30°

<

θ

<

75°

) with respect to a direction of a transmission axis of the polarizer and deviated by a predetermined angle θ

′

(0°

<

θ

′

<

90°

) with respect to a direction of an absorption axis of the polarizer.

2. The display device according to claim 1,

wherein the first polarized light separating means comprises a reflective polarizer which causes light that is a linear polarized light component in the first direction to be transmitted and which reflects light that is a linear polarized light component in a direction orthogonal to the first direction.

3. The display device according to claim 2,

wherein the reflective polarizer comprises a laminate formed by alternately stacking together birefringent first layers and second layers which have a refractive index that is substantially equal to one of a plurality of refractive indexes of the first layers and which are not birefringent.

4. The display device according to claim 1,

wherein the first polarized light separating means comprises a polarizer which allows light of the linear polarized light component in the first direction to be transmitted and absorbs the light of the linear polarized light component in a direction orthogonal to the first direction.

5. The display device according to claim 1,

wherein the second polarized light separating means comprises a reflective polarizer which causes light of the linear polarized light component in the second direction to be transmitted and reflects light of the linear polarized light component in a direction orthogonal to the second direction.

6. The display device according to claim 5,

wherein the reflective polarizer comprises a laminate formed by alternately stacking together birefringent first layers and second layers which have a refractive index that is substantially equal to one of a plurality of refractive indexes of the first layers and which are not birefringent.

7. The display device according to claim 1,

wherein the second polarized light separating means causes the linear polarized light component in the second direction to be transmitted and reflects light of the linear polarized light component in a direction orthogonal to the second direction with respect to light of substantially an entire wavelength range of visible light.

8. The display device according to claim 1,

wherein the transmission axis and the absorption axis of the polarizer are at right angles.

9. The display device according to claim 1,

wherein the predetermined angle θ

is 45 to 60 degrees.

10. The display device according to claim 1,

wherein the variable transmission polarization axis means comprise a liquid crystal element.

11. The display device according to claim 10,

wherein the variable transmission polarization axis means consists of a TN liquid crystal element, an STN liquid crystal element or an ECB liquid crystal element.

12. The display device according to claim 1,

wherein a second variable transmission polarization axis means is further provided on the opposite side of the variable transmission polarization axis means with respect to the second polarized light separating means.

13. The display device according to claim 12,

wherein the second variable transmission polarization axis means comprises a liquid crystal element.

14. The display device according to claim 13,

wherein the second variable transmission polarization axis means comprises a TN liquid crystal element, an STN liquid crystal element or an ECB liquid crystal element.

15. The display device according to claim 12,

wherein the second variable transmission polarization axis means is arranged between the second polarized light separating means and the polarizer.

16. The display device according to claim 1,

wherein light- transmissive light diffusion means is further provided between the light source and the first polarized light separating means.

17. An electronic apparatus equipped with a display device as claimed in claim 1.

18. A display device comprising:

a variable transmission polarization axis optical element;

a first polarized light separator which is arranged on one side of the variable transmission polarization axis optical element and which effects polarization separation by reflection or absorption;

a second polarized light separator which is arranged on another side of the variable transmission polarization axis optical element and which effects polarization separation by reflection;

a polarizer arranged on an opposite side of the variable transmission polarization axis optical element with respect to the second polarized light separator; and

a light source which is arranged on an opposite side of the second polarized light separator with respect to the polarizer and which applies light to the variable transmission polarization axis optical element side,

wherein a positional relationship between the second polarized light separator and the polarizer is determined such that the second direction is deviated by a predetermined angle θ

(30°

<

θ

<

75°

) with respect to a direction of a transmission axis of the polarizer and deviated by a predetermined angle θ

′

(0°

<

θ

′

<

90°

) with respect to a direction of an absorption axis of the polarizer.

19. A liquid crystal display device comprising:

a liquid crystal layer having a variable transmission polarization axis;

a first polarizer disposed on a first side of said liquid crystal layer;

a light scattering layer disposed on a second side of said liquid crystal layer;

a polarized light separator disposed on a side of said light scattering layer opposite said liquid crystal layer;

a second polarizer disposed on a side of said polarized light separator opposite said light scattering layer; and

a light source disposed on a side of said second polarizer opposite said polarized light separator;

wherein a transmission axis of said polarized light separator forms a predetermined angle θ

between 30 and 75 degrees relative to a transmission axis of said second polarizer and a predetermined angle θ

′

relative to an absorption axis of said second polarizer.

20. The device of claim 19 further comprising a phase difference film disposed between said liquid crystal layer and said first polarizer.

21. The device of claim 19 wherein said predetermined angle θ

is between 0° and

90°

, and said predetermined angle θ

′

is between 0° and

90°

.

22. The device of claim 21 wherein said predetermined angle θ

is between 45° and

60°

.

23. A display device comprising:

variable transmission polarization axis means capable of varying a transmission polarization axis;

first polarized light separating means which is arranged on one side of the variable transmission polarization axis means and which allows light that is a linear polarized light component in a first direction to be transmitted and reflects or absorbs light that is a linear polarized light component in a predetermined direction different from the first direction;

second polarized light separating means which is arranged on another side of the variable transmission polarization axis means and which allows light that is a linear polarized light component in a second direction to be transmitted and reflects light that is a linear polarized light component in a predetermined direction different from the second direction;

a polarizer arranged on an opposite side of the variable transmission polarization axis means with respect to the second polarized light separating means; and

a light source which is arranged on an opposite side of the second polarized light separating means with respect to the polarizer and which applies light to the variable transmission polarization axis means side,

wherein a positional relationship between the second polarized light separating means and the polarizer is determined such that the second direction is deviated by a predetermined angle θ

(0°

<

θ

<

90°

) with respect to a direction of a transmission axis of the polarizer and deviated by a predetermined angle θ

′

(0°

<

θ

′

<

90°

) with respect to a direction of an absorption axis of tie polarizer;

wherein the first polarized light separating means comprises a reflective polarizer which causes light that is a linear polarized light component in the first direction to be transmitted and which reflects light that is a linear polarized light component in a direction orthogonal to the first direction.