Projection display

• US 20050063184A1
• Filed: 04/07/2004
• Published: 03/24/2005
• Est. Priority Date: 09/17/2003
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Lee, Young-chol, Moon, Il-kweon, Kuratomi, Yasunori, Kim, Dong-ha
• Granted Patent: US 7,543,945 B2
• Time in Patent Office: Days
• US Class Current: 362/257
• CPC Class Codes: H04N 9/3111 for displaying the colours sequentially, e.g. by using sequentially activated light sources sequential projection in colour photography G03B33/08
• CPC Class Codes: H04N 9/315 Modulator illumination systems general applications of lighting devices F21V; general optical systems G02B; lamp houses for projectors not peculiar to the presence of an electronic spatial light modulator G03B21/20

Abstract

A projection display includes three illumination units to emit red, green, and blue beams, at least one optical modulator to modulate the red, green, and blue beams to be suitable for image data, and projection optics to magnify and project the light beams emitted from the at least one optical modulator. Each of the illumination units includes: a collimator including a parabolic first reflective surface; a compact light source located at a focal point of the first reflective surface; a polarizer that transforms a light beam emitted from the collimator into a P- or S-polarized beam; and an integrator that transforms the light beam emitted from the polarizer to be emitted at a uniform intensity of light.

Claims

1. A projection display comprising three illumination units to emit red, green, and blue beams, at least one optical modulator to modulate the red, green, and blue beams to be suitable for image data, and projection optics to magnify and project the light beams emitted from the at least one optical modulator, each of the illumination units comprising:

a collimator comprising a parabolic first reflective surface;

a compact light source located at a focal point of the first reflective surface;

a polarizer that transforms a light beam emitted from the collimator into a P- or S-polarized beam; and

an integrator that transforms the light beam emitted from the polarizer to be emitted at a uniform intensity of light.

2. The projection display of claim 1, wherein the compact light source is arrayed so that its optical axis is perpendicular to a principal axis of the first reflective surface.

3. The projection display of claim 2, wherein the collimator further comprises a second reflective surface which faces the first reflective surface and which comprises an optical window through which a light beam radiates from the compact light source.

4. The projection display of claim 3, wherein the collimator further comprises a third reflective surface which is slantingly formed at the edge of the optical window and reflects a light beam radiating at a smaller angle than an aperture angle toward the first reflective surface.

5. The projection display of claim 1, wherein the collimator further comprises a second reflective surface which faces the first reflective surface and which comprises an optical window through which a light beam radiates from the compact light source, the second reflective surface inclining with respect to the principal axis of the first reflective surface at a predetermined incidence angle and the compact light source being arrayed so that its optical axis inclines with respect to the principal axis at the same incidence angle as the predetermined incidence angle of second reflective surface.

6. The projection display of claim 5, wherein the collimator further comprises a third reflective surface which is slantingly formed at the edge of the optical window and reflects a light beam radiating at a smaller angle than an aperture angle toward the first reflective surface.

7. The projection display of claim 1, wherein the integrator comprises a rectangular parallelepiped glass rod.

8. The projection display of claim 1, wherein the integrator comprises a rectangular parallelepiped light tunnel with an inner reflective surface.

9. The projection display of claim 1, wherein the polarizer comprises:

a polarizing beam splitter that transmits one of P and S waves and reflects the other one; and

a λ

/2 plate that transforms one of the transmitted and reflected wave beams so as to have a different polarization orientation.

10. The projection display of claim 1, wherein the optical modulator is a reflective optical modulator which sequentially modulates the red, green, and blue beams emitted from the three illumination units.

11. The projection display of claim 10, wherein a λ

/4 plate and a polarizing beam splitter are sequentially installed in front of the reflective optical modulator, the polarizing beam splitter and the λ

/4 plate transmitting the red, green, and blue beams radiating from the illumination units, the reflective optical modulator modulating the red, green, and blue beams, the λ

/4 plate re-transmitting the red, green, and blue beams, and the polarizing beam splitter reflecting the red, green, and blue beams toward the projection optics.

12. The projection display of claim 1, wherein the at least one optical modulator comprises three transmittable optical modulators that modulate the red, green, and blue beams radiating from the illumination units, respectively, and the projection display further comprises a synthesizing prism that combines the red, green, and blue beams emitted from the transmittable optical modulators and irradiates the combined beam on the projection optics.

13. The projection display of claim 4, wherein:

the collimator is formed of a transparent body,

the first reflective surface of the collimator is coated with a reflective material so as to reflect the light beam radiating from the at least one optical modulator,

the second reflective surface of the collimator is coated with a reflective material except at the optical window, and

the third reflective surface of the collimator is coated with a reflective material.

14. The projection display of claim 6, wherein:

the collimator is formed of a transparent body,

the first reflective surface of the collimator is coated with a reflective material so as to reflect the light beam radiating from the at least one optical modulator,

the second reflective surface of the collimator is coated with a reflective material except at the optical window, and

the third reflective surface of the collimator is coated with a reflective material.

15. A projection display comprising three illumination units to emit red, green, and blue beams, an optical modulator to modulate the red, green, and blue beams accordingly to image data, and projection optics to magnify and project the light beams emitted from the optical modulator, each of the illumination units comprising:

a collimator that comprises a parabolic first reflective surface and a second reflective surface which faces the first reflective surface and which comprises an optical window through which light beams radiate in the vicinity of a focal point of the first reflective surface;

a compact light source located at the focal point of the first reflective surface;

a polarizer that transforms a light beam emitted from the collimator into a P- or S-polarized beam; and

a rectangular parallelepiped glass rod that transforms the polarized beam emitted from the polarizer to be emitted at a uniform intensity of light.

16. The projection display of claim 15, wherein the compact light source is arrayed so that its optical axis is perpendicular to a principal axis of the first reflective surface.

17. The projection display of claim 15, wherein the second reflective surface inclines with respect to the principal axis of the first reflective surface at a predetermined incidence angle and the compact light source is arrayed so that its optical axis inclines with respect to the principal axis at the same incidence angle as the predetermined incidence angle of second reflective surface.

18. The projection display of claim 15, wherein the collimator further comprises a third reflective surface which is slantingly formed at the edge of the optical window and reflects a light beam radiating at a smaller angle than an aperture angle toward the first reflective surface.

19. The projection display of claim 15, wherein the optical modulator is a reflective optical modulator which sequentially modulates the red, green, and blue beams emitted from the three illumination units.

20. The projection display of claim 19, wherein:

a λ

/4 plate and a polarizing beam splitter are sequentially installed in front of the reflective optical modulator,

the polarizing beam splitter and the λ

/4 plate transmit the red, green, and blue beams radiating from the illumination units,

the reflective optical modulator modulates the red, green, and blue beams,

the λ

/4 plate re-transmits the red, green, and blue beams, and

the polarizing beam splitter reflects the red, green, and blue beams toward the projection optics.

21. The projection display of claim 15, wherein the optical modulator comprises three transmittable optical modulators that modulate the red, green, and blue beams radiating from the illumination units, respectively, and the projection display further comprises a synthesizing prism that combines the red, green, and blue beams emitted from the transmittable optical modulators and irradiates the combined beam on the projection optics.

22. An illumination unit having a light source and to be used with a projection display, comprising:

a collimator comprising a parabolic first reflective surface;

a compact light source located at a focal point of the first reflective surface;

a polarizer that transforms a light beam emitted from the collimator into a P and S polarized beam; and

an integrator that transforms a light beam emitted from the polarizer to be emitted at a uniform intensity of light.

23. The illumination unit of claim 22, wherein the compact light source is arrayed so that its optical axis is perpendicular to a principal axis of the first reflective surface.

24. The illumination unit of claim 22, wherein the collimator further comprises a second reflective surface which faces the first reflective surface and which includes an optical window through which a light beam radiates from the compact light source.

25. The illumination unit of claim 24, wherein the second reflective surface inclines with respect to the principal axis of the first reflective surface at a predetermined incidence angle the compact light source is arrayed so that its optical axis inclines with respect to the principle axis at the same incidence angle as the predetermined incidence angle of the second reflective surface.

26. The illumination unit of claim 24, wherein the collimator further comprises a third reflective surface which is slantingly formed at the edge of the optical window and reflects a light beam radiating at a smaller angle than an aperture angle toward the first reflective surface.