Optical system for illuminating a light valve

• US 5,111,315 A
• Filed: 02/14/1991
• Issued: 05/05/1992
• Est. Priority Date: 02/14/1991
• Status: Expired due to Term

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Hughes Aircraft Company (Rtx Corporation)
• Inventors: Ledebuhr, Arno G.
• Primary Examiner(s): Heyman, John S.
• Assistant Examiner(s): GROSS, ANITA P
• Application Number:
  US07/658,139
• Time in Patent Office: 446 Days
• Field of Search: 359/40, 359/64, 359/496, 359/634, 359/638, 353/20, 353/33, 353/81, 353/122
• US Class Current: 349/5
• CPC Class Codes: G02F 1/133621 providing coloured light G02F1/133617, G02F1/133533 take precedence
• CPC Class Codes: G02F 1/133622 Colour sequential illumination
• CPC Class Codes: G02F 1/13473 for wavelength filtering or for colour display without the use of colour mosaic filters
• 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 color sequential illumination system (10) for a single light valve full-color projector is disclosed herein. The inventive color sequential system (10) is operative to illuminate a light valve (28) in response to an input beam. A prepolarizer arrangement (11, 13) polarizes optical energy of a first band of wavelengths within the input beam in a first state, and polarizes optical energy of a second band of wavelengths within the input beam in a second state. The system (10) includes a first liquid crystal switch (14), in optical alignment with the prepolarizer arrangement (11, 13), for selectively rotating the polarization states of optical energy within the first and second wavelength bands. A polarizer filter (18, 20), in optical alignment with the first liquid crystal switch (14), filters optical energy within the second wavelength band polarized in the predetermined state. A second liquid crystal switch (16), in optical alignment with the polarizer filter (18 20), selectively rotates the polarization states of optical energy within the first and second wavelength bands. The inventive system (10) also includes a broadband polarizer (24), in optical alignment with the second liquid crystal switch (16), for directing optical energy polarized in a predetermined state to the light valve (28).

Claims

1. An optical system for illuminating a light valve in response to an optical input beam, comprising:

prepolarizer means for polarizing optical energy of a first band of wavelengths within said input beam in a first state and for polarizing optical energy of a second band of wavelengths within said input beam in a second state;

first liquid crystal switch means, in optical alignment with said prepolarizer means, for selectively rotating the polarization states of optical energy within said first and second wavelength bands;

polarizer filter means, in optical alignment with said first liquid crystal switch means, for filtering optical energy within said second wavelength band polarized in a predetermined state;

second liquid crystal switch means, in optical alignment with said polarizer filter means, for selectively rotating the polarization states of optical energy within said first and second wavelength bands; and

broadband polarizer means, in optical alignment with said second liquid crystal switch means, for directing optical energy polarized in a predetermined state to said light valve.

2. The system of claim 1 wherein said prepolarizer means includes a first prepolarizer for polarizing optical energy within said first wavelength band and a second prepolarizer for polarizing optical energy within said second wavelength band.

3. The system of claim 1 wherein said polarizer filter means includes a polarizer for separating from said input beam optical energy within said second wavelength band having said predetermined polarization.

4. An optical system for illuminating a light valve in response to an optical input beam, comprising:

prepolarizer means for polarizing optical energy of a first band of wavelengths within said input beam in a first state and for polarizing optical energy of a second band of wavelengths within said input beam in a second state;

first liquid crystal switch means, in optical alignment with said prepolarizer means, for selectively rotating the polarization states of optical energy within said first and second wavelength bands;

polarizer filter means, in optical alignment with said first liquid crystal switch means, for filtering optical energy within said second wavelength band polarized in said second state;

second liquid crystal switch means, in optical alignment with said polarizer filter means, for selectively rotating the polarization states of optical energy within said first and second wavelength bands; and

broadband polarizer means, in optical alignment with said second liquid crystal switch means, for directing optical energy polarized in said second state to said light valve.

5. An optical system for illuminating a light valve in response to an optical input beam, comprising:

prepolarizer means for polarizing first, second and third bands of wavelengths within said input beam in predetermined states;

first liquid crystal switch means, in optical alignment with said prepolarizer means, for selectively rotating the polarization of optical energy within said first, second and third bands passing therethrough;

polarizer filter means, in optical alignment with said first liquid crystal switch means, for filtering optical energy within said second and third wavelength bands polarized in predetermined states;

second liquid crystal switch means, in optical alignment with said polarizer filter means, for selectively rotating the polarization states of optical energy within said first, second and third wavelength bands passing therethrough; and

broadband polarizer means, in optical alignment with said second liquid crystal switch means, for directing optical energy polarized in a predetermined state to said light valve.

6. An optical system for illuminating a light valve in response to an optical input beam, comprising:

prepolarizer means for polarizing a first band of wavelengths within said input beam in a first state, and for polarizing second and third bands of wavelengths within said input beam in a second state orthogonal to said first state;

first liquid crystal switch means, in optical alignment with said prepolarizer means, for selectively rotating the polarization of optical energy within said first wavelength band to said second state, and for selectively rotating the polarization of optical energy within said second and third bands to said first state;

polarizer filter means, in optical alignment with said first liquid crystal switch means, for filtering optical energy within said second and third wavelength bands polarized in predetermined states;

second liquid crystal switch means, in optical alignment with said polarizer filter means, for selectively rotating the polarization states of optical energy within said first, second and third wavelength bands passing therethrough; and

broadband polarizer means, in optical alignment with said second liquid crystal switch means, for directing to said light valve optical energy polarized in a predetermined state.

7. An optical system for illuminating a light valve in response to an optical input beam, comprising:

prepolarizer means for polarizing a green band of wavelengths within said input beam in a first state, and for polarizing red and blue bands of wavelengths within said input beam in a second state orthogonal to said first state;

first liquid crystal switch means, in optical alignment with said prepolarizer means, for selectively rotating the polarization of optical energy within said green wavelength band to said second state, and for selectively rotating the polarization of optical energy within said red and blue bands to said first state;

a red polarizer filter, in optical alignment with said first liquid crystal switch means, for filtering optical energy within said red wavelength band polarized in said second state;

a blue polarizer filter, in optical alignment with said first liquid crystal switch means, for filtering optical energy within said blue wavelength band polarized in said first state;

second liquid crystal switch means, in optical alignment with said polarizer filter means, for selectively rotating the polarization states of optical energy within said red, green and blue first, second and third wavelength bands; and

broadband polarizer means, in optical alignment with said second liquid crystal switch means, for directing to said light valve optical energy polarized in a predetermined state.

8. An optical system for illuminating a liquid crystal light valve in response to an optical input beam, comprising:

prepolarizer means for polarizing a green band of wavelengths within said input beam in a first state, and for polarizing red and blue bands of wavelengths within said input beam in a second state orthogonal to said first state;

first liquid crystal switch means, in optical alignment with said prepolarizer means, for selectively rotating the polarization of optical energy within said green wavelength band to said second state, and for selectively rotating the polarization of optical energy within said red and blue bands to said first state;

a red polarizer filter, in optical alignment with said first liquid crystal switch means, for filtering optical energy within said red wavelength band polarized in said second state;

a blue polarizer filter, in optical alignment with said first liquid crystal switch means, for filtering optical energy within said blue wavelength band polarized in said first state;

second liquid crystal switch means, in optical alignment with said polarizer filter means, for selectively rotating the polarization states of optical energy within said red, green and blue first, second and third wavelength bands;

broadband polarizer means, in optical alignment with said second liquid crystal switch means, for directing to said light valve optical energy polarized in a predetermined state; and

controller means for sequentially actuating said first and second liquid crystal switch means.

9. A method for illuminating a light valve by utilizing an optical input beam, comprising the steps of:

a) polarizing optical energy of a first band of wavelengths within said input beam in a first state, and polarizing optical energy of a second band of wavelengths within said input beam in a second state;

b) selectively rotating the polarization states of optical energy within said beam having said first and second wavelength bands;

c) filtering from said beam optical energy within said second wavelength band polarized in a predetermined state;

d) selectively rotating the polarization states of optical energy within said filtered beam included within said first and second wavelength bands; and

e) directing optical energy from said filtered beam polarized in a predetermined state to said light valve.