Projection display system for reflective light valves

• US 6,113,239 A
• Filed: 09/04/1998
• Issued: 09/05/2000
• Est. Priority Date: 09/04/1998
• Status: Expired due to Term

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Laboratories of America Incorporated (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Sampsell, Jeffrey B., Florence, James M.
• Primary Examiner(s): DOWLING, WILLIAM C
• Application Number:
  US09/148,727
• Time in Patent Office: 732 Days
• Field of Search: 353/20, 353/33, 353/31, 353/34, 353/38, 353/37, 353/30, 353/84, 353/81, 353/94, 349/9, 349/8, 349/5, 359/890, 359/492, 359/502, 359/501, 359/498
• US Class Current: 353/31
• 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 projection display system for reflective light valves includes a light source for generating a light beam having RGB light components, wherein the red light component is p-polarized and the green and blue light components are s-polarized; a reflector structure having plural polarizing beam splitter and dichroic filters therein, wherein each PBS and DF reflects a preselected light component and transmits a different preselected light component, and a LCD panel for generating a light-component-specific image associated with each light component; and a projection lens for projecting an image combined from the light-component-specific images from the LCDs; wherein a light-component-specific image passes through one and only one PBS and through one and only one DF between the LCD and the projection lens.

Claims

1. A projection display system for reflective light valves comprising:

a light source for generating a light beam having red-green-blue (RGB) light components;

a projection system having two polarizing beam splitters and two dichroic filters therein, wherein each polarizing beam splitter and dichroic filter reflects a preselected light component and transmits a different preselected light component, and a LCD panel for generating a light-component-specific image associated with each light component; and

a projection lens for projecting an image combined from the light-component-specific images from the LCDs;

wherein each light-component-specific image interacts with one and only one polarizing beam splitter and interacts with one and only one dichroic filter between the LCD and the projection lens.

2. The system of claim 1 wherein said light source includes a lamp and a filter stack having a cholesteric color filter mechanism located between said lamp and said projection system for pre-filtering said light beam to transmit red p-polarized light, green s-polarized light and blue s-polarized light.

3. The system of claim 2 wherein said filter stack includes, seriatim, a first filter constructed and arranged to reflect a right-handed circularly polarized portion of said red light component, to transmit a left-handed circularly polarized portion of said red light component and to transmit all of said green and blue light components;

a second filter constructed and arranged to reflect a left-handed circularly polarized portion of said green light component, to transmit a right-handed circularly polarized portion of said green light component and to transmit a left-handed circularly polarized portion of said red light and said blue light components; and

a third filter constructed and arranged to reflect a left-handed circularly polarized portion of said blue light component, to transmit a right-handed circularly polarized portion of said blue light component, to transmit a right-handed circularly polarized portion of said green light component, and to transmit a left-handed circularly polarized portion of said red light component.

4. The system of claim 3 which further includes a quarter-wave plate to convert the circularly polarized light components into linearly polarized light components.

5. The system of claim 1 wherein said polarizing beam splitters are arranged in a substantially straight line in said projection system, and wherein said dichroic filters are arranged in a substantially straight line in said projection system, and wherein said dichroic filters are normal to said polarizing beam splitters and arranged to intersect adjacent a mid-point of said substantially straight lines.

6. The system of claim 5 wherein said light beam from said light source impinges on a blue-transmitting dichroic filter at substantially 45 degrees, then impinges on a polarizing beam splitter at substantially 45 degrees, then impinges on an LCD panel along a direction normal to the plane of said LCD panel, having said light-component-specific image displayed thereon, and is reflected therefrom carrying a color image component, then impinges a polarizing beam splitter at substantially 45 degrees, then impinges a blue-reflecting dichroic filter at substantially 45 degrees prior to transitting said projection lens.

7. The system of claim 5 wherein said light beam from said light source impinges on a blue-transmitting dichroic filter at substantially 45 degrees, then impinges on a polarizing beam splitter at substantially 45 degrees, then impinges on an LCD panel along a direction normal to the plane of said LCD panel, having said light-component-specific image displayed thereon, and is reflected therefrom carrying a color image component, then impinges a polarizing beam splitter at substantially 45 degrees, then impinges a blue-transmitting dichroic filter at substantially 45 degrees prior to transitting said projection lens.

8. The system of claim 1 wherein said light source includes a lamp for generating said light beam and a pre-filtering illumination mechanism located between said lamp and said projection system for pre-filtering said light beam to provide a red p-polarized light component, a green s-polarized light component and a blue s-polarized light component to said projection system, wherein said pre-filtering illumination mechanism includes:

a red-transmitting dichroic filter, a pair of polarizing beam splitters, a pair of light absorbing stops, a half-wave plate, and a red-reflecting dichroic filter;

wherein said light beam impinges said red-transmitting dichroic filter, wherein said light beam is split into a transmitted red light component and reflected green light and blue light components;

said reflected green and blue light components impinge on a polarizing beam splitter, which reflects a green s-polarized light component and said blue light s-polarized component, wherein said green s-polarized light component and said blue light s-polarized component impinge said red-reflecting dichroic filter, which transmits said green s-polarized light component and said blue s-polarized light component to said projection system; and

wherein said transmitted red light component impinges another polarizing beam splitter, which reflects a red s-polarized light component through said half-wave plate, which changes said red s-polarized light component to a red p-polarized light component, which red p-polarized light component impinges said red-reflecting dichroic filter and is reflected to said projection system.

9. A projection display system for reflective light valves comprising:

a light source for generating a light beam having red-green-blue (RGB) light components, wherein the red light component is p-polarized and the green and blue light components are s-polarized;

a projection system having plural polarizing beam splitter and dichroic filters therein, wherein each polarizing beam splitter and dichroic filter reflects a preselected light component and transmits a different preselected light component, and a LCD panel for generating a light-component-specific image associated with each light component, wherein said polarizing beam splitters and said dichroic filters are arranged in a substantially "X" shaped configuration, wherein said dichroic filters are normal to said polarizing beam splitters and arranged to intersect adjacent an edge thereof; and

a projection lens for projecting an image combined from the light-component-specific images from the LCDs;

wherein each light-component-specific image interacts with one and only one polarizing beam splitter and interacts with one and only one dichroic filter between the LCD and the projection lens.

10. The system of claim 9 wherein said light source includes a lamp and a filter stack having a cholesteric color filter mechanism located between said lamp and said projection system for pre-filtering said light beam.

11. The system of claim 10 wherein said filter stack includes, seriatim, a first filter constructed and arranged to reflect a right-handed circularly polarized portion of said red light component, to transmit a left-handed circularly polarized portion of said red light component and to transmit all of said green and blue light components;

a second filter constructed and arranged to reflect a left-handed circularly polarized portion of said green light component, to transmit a right-handed circularly polarized portion of said green light component and to transmit a left-handed circularly polarized portion of said red light and said blue light components; and

a third filter constructed and arranged to reflect a left-handed circularly polarized portion of said blue light component, to transmit a right-handed circularly polarized portion of said blue light component, to transmit a right-handed circularly polarized portion of said green light component, and to transmit a left-handed circularly polarized portion of said red light component.

12. The system of claim 11 which further includes a quarter-wave plate to convert the circularly polarized light components into linearly polarized light components.

13. The system of claim 12 wherein said light beam from said light source impinges on a blue-transmitting dichroic filter at substantially 45 degrees, then impinges on a polarizing beam splitter at substantially 45 degrees, then impinges on an LCD panel along a direction normal to the plane of said LCD panel, having said light-component-specific image displayed thereon, and is reflected therefrom carrying a color image component, then impinges a polarizing beam splitter at substantially 45 degrees, then impinges a blue-reflecting dichroic filter at substantially 45 degrees prior to transitting said projection lens.

14. The system of claim 12 wherein said light beam from said light source impinges on a blue-transmitting dichroic filter at substantially 45 degrees, then impinges on a polarizing beam splitter at substantially 45 degrees, then impinges on an LCD panel along a direction normal to the plane of said LCD panel, having said light-component-specific image displayed thereon, and is reflected therefrom carrying a color image component, then impinges a polarizing beam splitter at substantially 45 degrees, then impinges a blue-transmitting dichroic filter at substantially 45 degrees prior to transitting said projection lens.

15. The system of claim 9 wherein said light source includes a lamp for generating said light beam and a pre-filtering illumination mechanism located between said lamp and said projection system for pre-filtering said light beam to provide a red p-polarized light component, a green s-polarized light component and a blue s-polarized light component to said projection system, wherein said pre-filtering illumination mechanism includes:

a red-transmitting dichroic filter, a pair of polarizing beam splitters, a pair of light absorbing stops, a half-wave plate, and a red-reflecting dichroic fitter;

wherein said light beam impinges said red-transmitting dichroic filter, wherein said light beam is split into a transmitted red light component and reflected green light and blue light components;

said reflected green and blue light components impinge on a polarizing beam splitter, which reflects a green s-polarized light component and said blue light s-polarized component, wherein said green s-polarized light component and said blue light s-polarized component impinge said red-reflecting dichroic filter, which transmits said green s-polarized light component and said blue s-polarized light component to said projection system; and

wherein said transmitted red light component impinges another polarizing beam splitter, which reflects a red s-polarized light component through said half-wave plate, which changes said red s-polarized light component to a red p-polarized light component, which red p-polarized light component impinges said red-reflecting dichroic filter and is reflected to said projection system.