Liquid crystal display polarizing beam splitter with specific incidence angle

• US 6,094,240 A
• Filed: 09/03/1997
• Issued: 07/25/2000
• Est. Priority Date: 09/04/1996
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Kondo, Katsumi, Adachi, Masaya, Hiyama, Ikuo, Itoh, Osamu
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): Horney, Kari M.
• Application Number:
  US08/922,754
• Time in Patent Office: 1,056 Days
• Field of Search: 349/9, 349/8, 349/5, 349/197, 359/488, 359/492, 359/491, 359/490, 359/495, 359/253, 359/500, 359/494
• US Class Current: 349/9
• CPC Class Codes: G02B 5/3016 involving passive liquid crystal elements optical properties of liquid crystals G02F1/0063; polarising elements associated with active liquid crystal devices G02F1/133528
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side
• CPC Class Codes: G02F 1/13362 providing polarized light, e.g. by converting a polarisation component into another one

Abstract

In a polarizing beam converter, a uniaxial anisotropic transparent medium is inserted and supported between isotropic transparent media; and an optical axis of said uniaxial anisotropic transparent medium is arranged almost perpendicular to an incident light beam or an incident face of the incident light beam at an interface between the isotropic transparent medium and the uniaxial anisotropic transparent medium. A half wavelength plate is placed with an inclined angle of 45° relative to a polarization axis for either of a reflected light component or a transmitted light component at the interface. The retractive index of the isotropic medium, n_p, and a refraction index n_e greater than n₀, of the uniaxial anisotropic transparent medium are substantially equal to one another. Further, at the interface of the isotropic medium and the uniaxial anisotropic transparent medium, an incident angle satisfying sin(θ)≧n₀ /n_p for satisfying a total reflection angle.

Claims

1. A polarizing beam splitter, wherein

a uniaxial anisotropic transparent medium is inserted and supported between isotropic transparent media;

an optical axis of said uniaxial anisotropic transparent medium is arranged almost perpendicular to incident light or an incident face of said incident light at an interface between said isotropic transparent medium and said uniaxial anisotropic transparent medium; and

a refraction index n_p of said isotropic medium and a refraction index n_e greater than n₀ of said uniaxial anisotropic transparent medium are substantially equal to each other, and at an interface of said isotropic medium and said uniaxial anisotropic transparent medium, an incident angle θ

is an angle satisfying sin(θ

)≧

n₀ /n_p for satisfying a total reflection angle.

5. The polarizing beam splitter of claim 1, 2, 3 or 4, wherein said isotropic transparent media is composed of an organic polymer material;

and

an incident angle of said incident light relative to said interface of said isotropic transparent media is 55°

or more.

2. A polarizing beam splitter, wherein

a uniaxial anisotropic transparent medium having birefringence Δ

n being 0.1 or more is inserted and supported between isotropic transparent media;

an optical axis of said uniaxial anisotropic transparent medium is arranged almost perpendicular to incident light or an incident face of said incident light at an interface between said isotropic transparent medium and said uniaxial anisotropic transparent medium; and

a refraction index n_p of said isotropic medium and a refraction index n_e greater than n₀ of said uniaxial anisotropic transparent medium are substantially equal to each other, and at an interface of said isotropic medium and said uniaxial anisotropic transparent medium, an incident angle θ

is an angle satisfying sin(θ

)≧

n₀ /n_p for satisfying a total reflection angle.

3. A polarizing beam splitter, wherein

a uniaxial anisotropic transparent medium having a refractive index n_e in an optical axis almost identical to a refractive index of an isotropic transparent medium is inserted and said supported between isotropic transparent media;

an optical axis of said uniaxial anisotropic transparent medium is arranged almost perpendicular to incident light or an incident face of said incident light at an interface between said isotropic transparent medium and said uniaxial anisotropic transparent medium; and

a refraction index n_p of said isotropic medium and said refraction index n_e greater than n₀ of said uniaxial anisotropic transparent medium are substantially equal to each other, and at an interface of said isotropic medium and said uniaxial anisotropic transparent medium, an incident angle θ

is an angle satisfying sin(θ

)≧

n₀ /n_p for satisfying a total reflection angle.

4. A polarizing beam splitter, wherein a uniaxial anisotropic transparent medium having a refractive index n_e in an optical axis almost identical to a refractive index of an isotropic transparent medium and having a birefringence Δ

n being 0.1 or more is inserted and said supported between isotropic transparent media;

an optical axis of said uniaxial anisotropic transparent medium is arranged almost perpendicular to incident light or an incident face of said incident light at an interface between said isotropic transparent medium and said uniaxial anisotropic transparent medium; and

a refraction index n_p of said isotropic medium and said refraction index n_e greater than n₀ of said uniaxial anisotropic transparent medium are substantially equal to each other, and at an interface of said isotropic medium and said uniaxial anisotropic transparent medium, an incident angle θ

is an angle satisfying sin(θ

)≧

n₀ /n_p for satisfying a total reflection angle.

6. A polarizing beam converter, comprising a polarizing beam splitter, wherein

a uniaxial anisotropic transparent medium is inserted and supported between isotropic transparent media;

an optical axis of said uniaxial anisotropic transparent medium is arranged almost perpendicular to incident light, or an incident face of said incident light, at an interface between said isotropic transparent medium and said uniaxial anisotropic transparent medium; and

a refraction index n_p of said isotropic medium and a refraction index n_e greater than n₀ of said uniaxial anisotropic transparent medium are substantially equal to each other, and at an interface of said isotropic medium and said uniaxial anisotropic transparent medium, an incident angle θ

is an angle satisfying sin(θ

)≧

n₀ /n_p for satisfying a total reflection angle;

wherein a half wavelength plate is placed with a inclined angle of 45°

relative to a polarization axis to intercept either of a light reflected at or light transmitted through said interface.

7. The polarizing beam converter of claim 6, wherein said uniaxial anisotropic transparent medium has a birefringence Δ

n of 0.1 or more.

8. The polarizing beam converter of claim 6, wherein said isotropic transparent media is composed of an organic polymer materia;

and

an incident angle of incident light relative to said interface of said isotropic transparent media is 55°

or more.

9. The polarizing beam converter of claim 6, wherein said half wavelength plate is formed as a twisted nematic liquid crystal cell without transparent electrodes and polarizing plates, said twisted nematic liquid crystal cell being twisted by 90°

.

10. The polarizing beam converter of claim 6, wherein said uniaxial anisotropic transparent medium is composed of a polymer-based liquid crystal.

11. A polarizing beam converter, comprising a polarizing beam splitter, wherein

a uniaxial anisotropic transparent medium is inserted and supported between isotropic transparent media;

an optical axis of said uniaxial anisotropic transparent medium is arranged almost perpendicular to incident light, or an incident face of said incident light, at an interface between said isotropic transparent medium and said uniaxial anisotropic transparent medium; and

a refraction index n_p of said isotropic medium and a refraction index n_e greater than n₀ of said uniaxial anisotropic transparent medium are substantially equal to each other, and at an interface of said isotropic medium and said uniaxial anisotropic transparent medium, an incident angle θ

is an angle satisfying sin (θ

)≧

n₀ /n_p for satisfying a total reflection angle;

wherein at least two half wavelength plates operating as polarizing beam converters are placed with a inclined angle of 45°

relative to a polarization axis for either of light reflected at or light transmitted through said interface; and

said polarizing beam converter further comprises a polarizing beam splitting surface for splitting a non-polarized light into a P-polarized light component and a S-polarized light component, with the mutual polarizing directions thereof intersecting in orthogonal axes.

12. A polarizing beam converter of claim 11, wherein an inclined angle to said incident light of said polarizing beam splitting surface for splitting non-polarized light into a P-polarized light component and a S-polarized light component is 70°

or less.

13. A liquid crystal display apparatus wherein plural polarizing beam converters are placed on a luminance apparatus of a direct-viewing-type liquid display apparatus;

said polarizing beam converters, formed as a half wavelength plates, have an inclined angle of 45°

relative to a polarization axis for either of light reflected at or light transmitted through an interface of a polarizing beam splitter;

said polarizing beam splitter is so configured that a uniaxial anisotropic transparent medium is inserted and supported between isotropic transparent media;

an optical axis of said uniaxial anisotropic transparent medium is arranged almost perpendicular to incident light, or an incident face of said incident light, at an interface between said isotropic transparent medium and said uniaxial anisotropic transparent medium; and

a refraction index n_p of said isotropic medium and a refraction index n_e greater than n₀ of said uniaxial anisotropic transparent medium are substantially equal to each other, and at an interface of said isotropic medium and said uniaxial anisotropic transparent medium, an incident angle θ

is an angle satisfying sin(θ

)≧

n₀ /n_p for satisfying a total reflection angle.

14. A projection-type liquid crystal display apparatus having a liquid crystal display device;

and

a light source and a projection lens for projecting a display image developed by a liquid crystal display device onto a screen surface, comprising;

a polarizing beam converter, having a polarizing beam splitting surface for splitting a non-polarized light into a P-polarized light component and a S-polarized light component, the mutual polarizing directions thereof intersecting in orthogonal;

wherein a uniaxial anisotropic transparent medium is inserted and supported between isotropic transparent media;

an optical axis of said uniaxial anisotropic transparent medium is arranged almost perpendicular to incident light, or an incident face of said incident light, at an interface between said isotropic transparent medium and said uniaxial anisotropic transparent medium; and

a refraction index n_p of said isotropic medium and a refraction index n_e greater than n₀ of said uniaxial anisotropic transparent medium are substantially equal to each other, and at an interface of said isotropic medium and said uniaxial anisotropic transparent medium, an incident angle θ

is an angle satisfying sin(θ

)≧

n₀ /n_p for satisfying a total reflection angle;

wherein a half wavelength plate is placed with an inclined angle of 45°

relative to a polarization axis for either of light reflected at or light transmitted through said interface.

15. A projection-type liquid crystal display apparatus of claim 14, wherein at least two polarizing beam converters are provided.

16. A polarizing beam splitter, wherein

a uniaxial anisotropic transparent medium having a thickness thicker than a wavelength of a visual light is inserted and supported between isotropic transparent media;

an optical axis of said uniaxial anisotropic transparent medium is arranged almost perpendicular to incident light or an incident face of said incident light at an interface between said isotropic transparent medium and said uniaxial anisotropic transparent medium; and

a refraction index n_p of said isotropic medium and a refraction index n_e greater than n₀ of said uniaxial anisotropic transparent medium are substantially equal to each other, and at an interface of said isotropic medium and said uniaxial anisotropic transparent medium, an incident angle θ

is an angle satisfying sin(θ

)≧

n₀ /n_p for satisfying a total reflection angle.