Two lamp, single light valve projection system

• US 6,147,720 A
• Filed: 12/27/1995
• Issued: 11/14/2000
• Est. Priority Date: 12/27/1995
• Status: Expired due to Fees

• Current Assignee: Philips Electronics North America Corporation (Koninklijke Philips N.V.)
• Original Assignee: Philips Electronics North America Corporation (Koninklijke Philips N.V.)
• Inventors: Guerinot, deceased, William F., Guerinot, legal representative, by Marlene, Stanton, Douglas A., Brennesholtz, Matthew Scott
• Primary Examiner(s): Peng, John K.
• Assistant Examiner(s): LO, LINUS H
• Application Number:
  US08/579,655
• Time in Patent Office: 1,784 Days
• Field of Search: 348/742, 348/743, 348/744, 348/750, 348/751, 348/752, 348/754-756, 348/68, 348/69, 348/70
• US Class Current: 348/744
• CPC Class Codes: H04N 9/3114 by using a sequential colour filter producing one colour at a time
• CPC Class Codes: H04N 9/3164 using multiple light sources

Abstract

A projection system includes first and second light sources which are disposed at an angle with respect to each other and are activated during respective different phases of an illumination cycle to illuminate a spot on different sides of a segmented rotary filter wheel. The filter wheel is alternately used to transmit light from one of the light sources, and to reflect light from the other light source, to a light valve, the output of which is projected onto a screen. The wheel segments may be alternately clear and mirrored or may alternately transmit and reflect colors to produce color sequential illumination of the light valve. In addition to filter wheels producing sequences of red, blue, green illumination, including the possibility of splitting a color phase into non-adjacent smaller phases to reduce color artifacts, a simple filter wheel which in two rotations produces a sequence of red, blue, green, cyan, magenta, yellow color illumination, resulting in an expanded color gamut, is also disclosed. Blanking intervals during which both lamps are turned off span each passage of a segment boundary through the spot.

Claims

1. A projection system comprising:

a segmented rotatable wheel having at least a first light transmissive segment and a second light reflective segment;

first and second light sources disposed at an angle with respect to each other and with respect to said wheel such that each light source illuminates a focused spot on a different side of the wheel at the same location;

power supply means for alternately energizing said first and second light sources during respective different phases of a light source illumination cycle; and

a light valve positioned to receive light from the spot illuminated by the first light source after transmission through the first segment of the wheel and from the spot illuminated by the second light source after reflection from the second segment of the wheel, for modulating the received light in response to a signal representing an image to form an image carrying output light beam.

2. The system as claimed in claim 1, wherein said wheel has an even number of segments, one half the number of segments being used in transmission alternating with the other half of the segments being used in reflection.

10. The system as claimed in claim 1, wherein said first and second light sources are energized during alternate revolutions of said wheel such that said illumination cycle comprises two revolutions of said wheel and said wheel has at least three light filtering segments for producing a set of six colors, each segment being used in reflection and in transmission in alternate revolutions of said wheel.

11. The system as claimed in claim 1, wherein neither of the first or second light sources is energized during intervals during which boundaries between segments of the wheel pass through the area that would be illuminated by said light sources, if energized.

12. The system as claimed in claim 2, wherein neither of the first or second light sources is energized during intervals during which boundaries between segments of the wheel pass through the area that would be illuminated by said light sources, if energized.

20. The system as claimed in claim 10, wherein neither of the first or second light sources is energized during intervals during which boundaries between segments of the wheel pass through the area that would be illuminated by said light sources, if energized.

3. A projection system comprising:

a segmented rotatable wheel;

first and second light sources disposed at an angle with respect to each other and with respect to said wheel such that each light source illuminates a focused spot on a different side of the wheel at the same location;

power supply means for alternately energizing said first and second light sources during respective different phases of a light source illumination cycle; and

a light valve positioned to receive light from the spot illuminated by the first light source after transmission through the wheel and from the spot illuminated by the second light source after reflection from the wheel, for modulating the received light in response to a signal representing an image to form an image carrying output light beam,

wherein said wheel has six color filtering segments, three segments which are used in transmission for transmitting different ones of a set of three colors from said first light source toward said light valve and three segments which are used in reflection for reflecting different ones of said three colors from said second light source toward said light valve, said segments being arranged and said wheel being synchronized in rotation with the activation of the first and second light sources such that the path portion from the first light source to said one side of the wheel and the path portion from said other side of the wheel to the light value are coupled by a segment used in transmission when the first light source is energized and said path portion from the second light source to said other side of the wheel and said path portion from said other side of the wheel to the light valve are coupled by a segment used in reflection when the second light source is energized.

13. The system as claimed in claim 3, wherein neither of the first or second light sources is energized during intervals during which boundaries between segments of the wheel pass through the area that would be illuminated by said light sources, if energized.

4. a projection system comprising:

a segmented rotatable wheel;

first and second light sources disposed at an angle with respect to each other and with respect to said wheel such that each light source illuminates a focused spot on a different side of the wheel at the same location;

power supply means for alternately energizing said first and second light sources during respective different phases of a light source illumination cycle; and

a light valve positioned to receive light from the spot illuminated by the first light source after transmission through the wheel and from the spot illuminated by the second light source after reflection from the wheel, for modulating the received light in response to a signal representing an image to form an image carrying output light beam,

wherein said wheel has at least three light filtering segments for producing a set of first, second and third colors, including a first segment for transmitting the first color of said set from said first light source toward said light valve, a second segment for transmitting a second color of said set from said first light source toward said light valve and a third segment for reflecting the third color of said set from said second light source to said light valve.

5. The system of claim 4, wherein said wheel has fourth segment, which is not angularly adjacent to said second segment, for transmitting said second color from said first light source toward said light valve.

6. The system of claim 4, wherein the first light source is relatively richer in the first and second colors and the second light source is relatively richer in said third color.

8. The system of claim 6, wherein said wheel has a fourth segment, which is not angularly adjacent to said second segment, for reflecting said second color from said first light source toward said light valve.

9. The system of claim 6, wherein the first light source is relatively richer in the first color and the second light source is relatively richer in said second and third colors.

14. The system as claimed in claim 4, wherein neither of the first or second light sources is energized during intervals during which boundaries between segments of the wheel pass through the area that would be illuminated by said light sources, if energized.

15. The system as claimed in claim 5, wherein neither of the first or second light sources is energized during intervals during which boundaries between segments of the wheel pass through the area that would be illuminated by said light sources, if energized.

16. The system as claimed in claim 6, wherein neither of the first or second light sources is energized during intervals during which boundaries between segments of the wheel pass through the area that would be illuminated by said light sources, if energized.

18. The system as claimed in claim 8, wherein neither of the first or second light sources is energized during intervals during which boundaries between segments of the wheel pass through the area that would be illuminated by said light sources, if energized.

19. The system as claimed in claim 9, wherein neither of the first or second light sources is energized during intervals during which boundaries between segments of the wheel pass through the area that would be illuminated by said light sources, if energized.

7. A projection system comprising:

a segmented rotatable wheel;

first and second light sources disposed at an angle with respect to each other and with respect to said wheel such that each light source illuminates a focused spot on a different side of the wheel at the same location;

power supply means for alternately energizing said first and second light sources during respective different phases of a light source illumination cycle; and

a light valve positioned to receive light from the spot illuminated by the first light source after transmission through the wheel and from the spot illuminated by the second light source after reflection from the wheel, for modulating the received light in response to a signal representing an image to form an image carrying output light beam,

wherein said wheel has at least three light filtering segments for producing a set of first, second and third colors, including a first segment for transmitting the first color of said set from said first light source toward said light valve, a second segment for reflecting a second color of said set from said second light source toward said light valve and a third segment for reflecting the third color of said set from said second light source to said light valve.

17. The system as claimed in claim 7, wherein neither of the first or second light sources is energized during intervals during which boundaries between segments of the wheel pass through the area that would be illuminated by said light sources, if energized.