Two channel field sequential color display system

• US 5,534,949 A
• Filed: 04/08/1994
• Issued: 07/09/1996
• Est. Priority Date: 04/08/1994
• Status: Expired due to Fees

• Current Assignee: Hughes Aircraft Company (Rtx Corporation)
• Original Assignee: Hughes Aircraft Company (Rtx Corporation)
• Inventors: Baron, Peter C.
• Primary Examiner(s): Kostak, Victor R.
• Assistant Examiner(s): Acosta, Juan G.
• Application Number:
  US08/224,912
• Time in Patent Office: 823 Days
• Field of Search: 348/742, 348/776, 348/778, 348/750, 348/758
• US Class Current: 348/742
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• CPC Class Codes: G09G 3/002 to project the image of a two-dimensional display, such as an array of light emitting or modulating elements or a CRT
• CPC Class Codes: H04N 9/3105 for displaying all colours simultaneously, e.g. by using two or more electronic spatial light modulators simultaneous projection in colour photography G03B33/10; beam splitting or combining systems per se G02B27/10
• CPC Class Codes: H04N 9/3167 for polarizing the light beam polarizing optical systems per se G02B27/28

Abstract

A two-channel field sequential display system utilizes both simultaneous and sequential color display methods to display full color images in a way that is less complex, smaller in size and less costly than prior art additive color systems, while exhibiting higher light output and fewer temporal visual effects than prior art single-channel field sequential color display systems. The two-channel field sequential display system displays two of three primary colors that make up the image simultaneously during a portion of a display frame and displays the third primary color sequentially during a subsequent part of the display frame. The two-channel field sequential color display concept may be applied to any projection system which combines individual monochrome projector outputs to form an image on a screen or to any display technique that is capable of superimposing two images. The projectors can be implemented with any reflective or transmissive light valve based projection system, or any appropriately color modulated emissive source.

Claims

1. A two-channel field sequential color display system for generating a color image in response to electronic image signals, said two-channel field sequential color display system comprising:

a first active matrix liquid crystal light valve,

a second active matrix liquid crystal light valve, and

a controller for controlling said first and second active matrix liquid crystal light valves, to simultaneously display an image in a first and second color, respectively, during one part of a display frame, said images from said first and second image generators being superimposed on an image plane, and to display said image in a third color during a different part of said display frame, said image from said first and/or second image generators being displayed on said image plane during said different part of said display frame at the same location on said image plane as said images displayed during said one part of said display frame.

2. The system of claim 1, wherein said active matrix liquid crystal light valves are line sequentially addressed.

3. A two-channel field sequential color display system for generating a color image in response to electronic image signals, said color of said image having three color components, said two-channel field sequential color display system comprising:

an unpolarized white light source for generating randomly polarized white light,

a collimator for collimating said white light,

a color polarization switch for receiving and splitting said white light into three color components and for polarizing a first of said color components into S or P polarization, for polarizing a second of aid color components into a polarization orthogonal to said polarization of said first color component, and for polarizing a third color component into an S or P polarization,

a display controller for storing said image signals and for controlling and timing the output of said color components,

a polarizing light divider for receiving and splitting said polarized color components from said color polarization switch, said polarizing light divider transmitting either an S or a P polarization component and reflecting a polarization component that is orthogonal to the polarization component transmitted,

a first reflective active matrix liquid crystal light valve for receiving said image signals from said display controller and for imparting said image signals from said image onto a first of said color components transmitted by said polarizing light divider during one part of a display frame, said light valve imparting an intensity distribution onto said color component that corresponds to the distribution of said first color component in said color image, said light valve retro-reflecting said image-bearing first color component back toward said polarizing light divider and rotating the polarization of said reflected first color component by 90 degrees such that said reflected first color component undergoes reflection at said polarizing light divider,

a second reflective active matrix liquid crystal light valve for receiving said image signals from said display controller and for imparting said image onto a second of said color components reflected by said polarizing light divider during said one part of said display frame, said light valve imparting an intensity distribution onto said second color component that corresponds to the distribution of said second color component in said color image, said light valve retro-reflecting said image-bearing second color component back toward said polarizing light divider and rotating the polarization of said reflected second color component by 90 degrees, such that said reflected color component undergoes transmission at said polarizing light divider, said image-bearing reflected first and second color components from said first light valve and said second light valve recombining at said polarizing light divider, and

an imager for simultaneously re-imaging said image imparted onto said recombined first and second color components onto an image plane during said one part of said display frame,

said polarizing light divider reflecting and/or transmitting the third of said three color components during a different part of said display frame,

said first and/or second active, matrix light valves receiving said image signals from said display controller and imparting said image onto said third color component reflecting and/or transmitted by said polarizing light divider during said different part of said display from, said first and or second light valves imparting an intensity distribution onto aid third color component that corresponds to the distribution of said color component in said color image, said first and/or second active matrix light valves retro-reflecting said image-bearing third color component back toward said polarizing light divider and rotating the polarization of said reflected third color component by 90 degrees, such that said reflected third color component undergoes transmission and/or reflection at said polarizing light divider,

said imager re-imaging said image imparted onto said third color component onto said image plane during said different part of said display frame at the same location on said image plane as said image displayed during said one part of said display frame.

4. The system of claim 3, wherein said reflective active matrix liquid crystal light valves are line sequentially addressed.

5. The system of claim 3, wherein said color polarization switch comprises:

a polarizing light divider for receiving and dividing said randomly polarized white light into S and P polarization components, said polarizing light divider transmitting either said S or P polarization component and reflecting the other polarization component,

a wavelength separator for separating said white light into red, green and blue color components,

a shutter for selectively blocking said red color component, and

a blue/green switch for blocking a selectable one of said green and blue color components.

6. The system of claim 5, wherein said polarizing light divider comprises a polarizing beamsplitter.

7. The system of claim 5, wherein said wavelength separator comprises:

a first dichroic mirror for extracting said red color component from said white light, and

a second dichroic mirror for extracting said green and blue color components from said white light.

8. The system of claim 3, wherein said imager comprises a lens.

9. The system of claim 3, wherein said polarizing light divider comprises a polarizing beamsplitter.

10. A two-channel field sequential color display system for generating a color image in response to electronic image signals, said color on said image having three color components, said two-channel field sequential color display system comprising:

an unpolarized white light source for generating randomly polarized white light,

a collimator for collimating said white light,

a color polarization switch for receiving and splitting said white light into three color components and for polarizing a first of said color components into S or P polarization, for polarizing a second of said color components into a polarization orthogonal to said polarization of said first color component, and for polarizing a third color component into an S or P polarization,

a display controller for storing said image signals and for controlling and timing the output of said color components,

a first polarizing light divider for receiving and splitting said polarized color components from said color polarization switch, said polarizing light divider transmitting either an S or a P polarization component and reflecting a polarization component that is orthogonal to the polarization component transmitted,

a first transmissive line sequentially addressed active matrix liquid crystal light valve for receiving said image signals form said display controller and for imparting said image onto a first of said color components transmitted by said polarizing light divider during one part of display frame, said light valve imparting an intensity distribution only said color component that corresponds [to the distribution of said first color component in said color image, said light valve rotating the polarization of said reflected first color component by 90 degrees,

a second transmissive line sequentially addressed active matrix liquid crystal light valve for receiving said image signals from said display controller and for imparting said image onto a second of said color components transmitted by said polarizing light divider during one part of a display frame, said light valve imparting an intensity distribution on said second color component that corresponds to the distribution of said second color component in said color image, said light valve rotating the polarization of said reflected second color component by 90 degrees,

a second polarizing light divider for receiving said first and second color components from said first and second light valves, said light divider recombining said first and second color components, and

an imager for simultaneously re-imagining said image imparted onto said recombined first and second color components onto an image plane during said one part of said display fame,

said first polarizing light divider reflecting and/or transmitting the third of said three color components during a different part of said display frame,

said first and/or second line sequentially addressed active matrix light valves receiving said image signals from said display controller and imparting said image on said third color component reflected and/or transmitted by said first polarizing light divide during said different part of said display frame, said first and/or second line sequentially addressed active matrix light valves imparting an intensity distribution on said third color component in said color image, said first and/or second line sequentially addressed active matrix light valves rotating the polarization of said third color component by 90 degrees,

said second polarizing light divider receiving said third color component from said first and/or second light valves and transmitting and/or reflecting said third color component from said first and/or second light valves,

said imager re-imaging said image imparted onto said third color component onto said image plane during said different part of said display frame at the same location on said image plane as said image displayed during said one part of said display frame.

11. The system of claim 10, wherein said color polarization switch comprises:

a polarizing light divider for receiving and dividing said randomly polarized white light into S and P polarization components, said polarizing light divider transmitting either said S or P polarization component and reflecting the other polarization component,

a wavelength separator for separating said white light into red, green and blue color components,

a shutter for selectively blocking said red color component, and

a blue/green switch for blocking a selectable one of said green and blue color components.

12. The system of claim 11, wherein said polarizing light divider comprises a polarizing beamsplitter.

13. The system of claim 11, wherein said wavelength separator comprises:

a first dichroic mirror for extracting said red color component from said white light, and

a second dichroic mirror for extracting said green and blue color components from said white light.

14. The system of claim 10, wherein said imager comprises a lens.

15. The system of claim 10, wherein said first and second polarizing light dividers comprise first and second polarizing beamsplitters.

16. A method of generating color images in response to an electronic signal, said color on said image having three color components, said method comprising the steps of:

generating two images in a selectable two of said three color components during one part of a display frame using line sequentially addressed active matrix liquid crystal light valves, said two images generated in said two color components having an intensity distribution that corresponds to the distribution of said color components in said color image,

displaying said two images simultaneously on a screen during said one part of said display frame such that said two images overlap on said screen,

during a different part of said display frame, generating a third image in the one of said three color components not displayed during said one part of said display frame, said third image generated in said color component having an intensity distribution that corresponds to the distribution of said color component in said color images, and

displaying said third image on said screen during said different part of said display frame at the same location on said screen as said two images displayed during said part of said display frame.