PROJECTION SYSTEM

• US 20090268166A1
• Filed: 02/16/2009
• Published: 10/29/2009
• Est. Priority Date: 04/29/2008
• Status: Active Grant

• Current Assignee: Himax Display Incorporated (Himax Technologies Incorporated), Himax Technologies Ltd. (Himax Technologies Incorporated)
• Original Assignee: Himax Display Incorporated (Himax Technologies Incorporated), Himax Technologies Ltd. (Himax Technologies Incorporated)
• Inventors: Wu, Teng-Kuei, Huang, Ho-Chi, Chen, Chun-Min
• Granted Patent: US 8,764,198 B2
• Time in Patent Office: Days
• US Class Current: 353/20
• CPC Class Codes: G02B 17/0856 comprising a refractive element with a reflective surface, the reflection taking place inside the element, e.g. Mangin mirrors
• CPC Class Codes: G02B 19/0028 refractive and reflective surfaces, e.g. non-imaging catadioptric systems
• CPC Class Codes: G02B 19/0061 the light source comprising a LED semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission H01L33/00
• CPC Class Codes: G02B 27/283 used for beam splitting or combining
• CPC Class Codes: G03B 21/2033 LED or laser light sources
• CPC Class Codes: G03B 21/2073 Polarisers in the lamp house peculiar to electronic spatial light modulators H04N9/3197
• CPC Class Codes: H04N 9/3152 for shaping the light beam beam shaping per se G02B27/09
• CPC Class Codes: H04N 9/3167 for polarizing the light beam polarizing optical systems per se G02B27/28

Abstract

A projection system including an illumination unit, a polarization conversion unit, a light valve, a projection lens, and a polarizing beam split (PBS) element is provided. The polarization conversion unit includes a V-shaped PBS element, a wave plate, and two reflective surfaces. The V-shaped PBS element includes a first PBS portion and a second PBS portion. The first PBS portion is adapted to be passed through by a first partial beam with a first polarization direction and reflect a second partial beam with a second polarization direction. The second PBS portion is adapted to be passed through by a third partial beam with the first polarization direction and reflect a fourth partial beam with the second polarization direction. The wave plate is disposed in the transmission paths of the first partial beam and the third partial beam. The reflective surfaces are located at opposite sides of the V-shaped PBS element.

Claims

1. A projection system comprising:

an illumination unit for emitting a light beam;

a polarization conversion unit disposed in the transmission path of the light beam and comprising;

a V-shaped polarizing beam split (PBS) element comprising;

a first PBS portion adapted to be passed through by a first partial beam of the light beam with a first polarization direction and reflect a second partial beam of the light beam with a second polarization direction; and

a second PBS portion connected to the first PBS portion, wherein an angle greater than 0 degree and less than 180 degrees is included between the first PBS portion and the second PBS portion, the second PBS portion is adapted to be passed through by a third partial beam of the light beam with the first polarization direction and reflect a fourth partial beam of the light beam with the second polarization direction;

a wave plate disposed in the transmission paths of the first partial beam from the first PBS portion and the third partial beam from the second PBS portion, wherein the wave plate is adapted to convert the first partial beam and the third partial beam with the first polarization direction into a fifth partial beam with the second polarization direction; and

two reflective surfaces located at two opposite sides of the V-shaped PBS element and adapted to respectively reflect the second partial beam and the fourth partial beam from the V-shaped PBS element, wherein the second partial beam and the fourth partial beam from the reflective surfaces and the fifth partial beam from the wave plate are combined into an illumination beam with the second polarization direction;

a light valve disposed in the transmission path of the illumination beam and adapted to convert the illumination beam into an image beam;

a projection lens disposed in the transmission path of the image beam; and

a PBS element disposed in the transmission paths of the illumination beam and the image beam and adapted to allow the illumination beam to be transmitted to the light valve and to allow the image beam to be transmitted to the projection lens.

2. The projection system according to claim 1, wherein the wave plate is a half wave plate.

3. The projection system according to claim 1, wherein the polarization conversion unit further comprises:

a first prism;

a second prism leaning against the first prism, wherein the first PBS portion is a PBS film located at a junction surface of the first prism and the second prism, and one of the reflective surfaces is located on the second prism; and

a third prism leaning against the first prism, wherein the second PBS portion is a PBS film located at a junction surface of the first prism and the third prism, and the other one of the reflective surfaces is located on the third prism.

4. The projection system according to claim 1, wherein the reflective surfaces are total internal reflection surfaces to totally internally reflect the second partial beam and the fourth partial beam respectively.

5. The projection system according to claim 1, wherein the polarization conversion unit further comprises two reflective films respectively disposed on the two reflective surfaces to reflect the second partial beam and the fourth partial beam respectively.

6. The projection system according to claim 1, wherein the two reflective surfaces are curved surfaces.

7. The projection system according to claim 1, wherein the light beam emitted from the illumination unit is along an optic axis for a projection system, and the illumination unit comprises:

an LED die; and

a collimator lens comprising;

a central part having a first light transmission surface and a second light transmission surface opposite to the first light transmission surface; and

a peripheral part around the central part having an inner refraction wall coupled to the first light transmission surface to form a hollow for situating the LED die, an outer reflection wall opposite to the inner refraction wall, and a refraction surface connecting to the second light transmission surface and the outer reflection wall,

wherein both the central part and the peripheral part of the collimator lens are rotationally asymmetrical corresponding to the optic axis.

8. The projection system as claimed in claim 7, wherein a front view of the central part is a first oval shape and a front view of the peripheral part is a second oval shape.

9. The projection system as claimed in claim 8, wherein the aspect ratio of the first oval shape is between 91% and 99% and the aspect ratio of the second oval shape is between 91% and 99%.

10. The projection system as claimed in claim 7, wherein the collimator lens is one piece of plastic element.

11. The projection system as claimed in claim 7, wherein the illumination unit further comprises an optically transmissive encapsulant covering the LED die.

12. The projection system as claimed in claim 7, wherein the refraction surface of the peripheral part further comprising a first curved surface connecting to the second light transmission surface and a flat surface connecting to the outer reflection wall.

13. The projection system as claimed in claim 7, wherein the first light transmission surface and the second light transmission surface of the central part of the collimator lens are spherical or aspherical.

14. The projection system as claimed in claim 7, wherein the outer reflection wall of the peripheral part of the collimator lens is formed with a reflected mirror, a total internal reflection, or a dielectric coating.

15. The projection system as claimed in claim 7, wherein the central part of the collimator lens is a condenser lens.

16. The projection system as claimed in claim 7, wherein the central part of the collimator lens passes light into a small cone between 10 and 20 degrees.

17. The projection system as claimed in claim 7, wherein the peripheral part of the collimator lens passes light into a small cone between 10 and 20 degrees.

18. The projection system as claimed in claim 7, wherein the height of the collimator lens is between 5 to 15 mm.

19. The projection system as claimed in claim 7, wherein the width of the collimator lens is between 10 to 25 mm.