High resolution, high intensity video projection cathode ray tube provided with a cooled reflective phosphor screen support

• US 5,801,792 A
• Filed: 12/13/1995
• Issued: 09/01/1998
• Est. Priority Date: 12/13/1995
• Status: Expired due to Fees

• Current Assignee: SWZ Engineering, Ltd.
• Original Assignee: SWZ Engineering, Ltd.
• Inventors: Campbell, Frank A., Writer, Philip L., Smith, Ceil E.
• Primary Examiner(s): Kostak, Victor R.
• Application Number:
  US08/572,165
• Time in Patent Office: 993 Days
• Field of Search: 348/749, 348/761, 348/748, 313/30-36
• US Class Current: 348/749
• CPC Class Codes: H01J 29/006 Arrangements for eliminating unwanted temperature effects
• CPC Class Codes: H01J 29/894 Arrangements combined with the vessel for the purpose of image projection on a screen projection arrangements for image reproduction, e.g. using eidophor H04N5/74
• CPC Class Codes: H04N 9/31 Projection devices for colour picture display , e.g. using electronic spatial light modulators [ESLM]

Abstract

A single gun projection cathode ray tube (CRT) which permits the generation of high brightness image output. The crux of the invention is the provision, in the CRT, of an optically reflecting high thermal conductivity metal plate-like member positioned in the path of the electron beam, the surface of the metal plate-like member, which is directed toward both the electron gun and the faceplate of the CRT, being coated with a monochrome phosphor and being cooled by external means. The CRT is capable of producing monochrome images which are reflected by the phosphor-bearing surface of the metal plate-like member toward the faceplate of the CRT and, upon passing through the faceplate, may be projected directly onto a display screen. Alternatively, the CRT can produce projected field sequential color images when it is used either with a synchronized color wheel or with a synchronized liquid crystal shutter color filter interposed between the metal plate-like member of the CRT and the associated display screen.

Claims

1. A single-gun projection cathode ray tube for generating a projected high resolution, high light output video image, the cathode ray tube having an axis, a glass faceplate transverse to said axis, an electron gun for generating a high intensity electron beam, a control grid positioned across the path of the electron beam out of said electron gun and connected for receiving video signals, and a phosphor screen interposed between the electron gun and the faceplate and adapted, when impinged upon by the electron beam, to generate optical images for transmission through said faceplate;

wherein the improvement comprises;

(a) said electron gun is arranged to initially direct said high intensity electron beam along a path transverse to and intersecting said axis at a location remote from said faceplate of the cathode ray tube;

(b) a thermally conductive metal plate-like member is arranged in the cathode ray tube at a location remote from said faceplate and has an optically reflective first surface directed toward both said electron gun and said faceplate;

(c) the phosphor screen is supported by said metal plate-like member on said first surface thereof in a position to be struck by said high intensity electron beam and to generate resultant corresponding optical images, and said optically reflective first surface of said metal plate-like member serves to reflect said optical images developed on said phosphor screen toward said faceplate of the cathode ray tube for passage therethrough to a display screen; and

(d) cooling means are provided in heat exchange relation with said metal plate-like member for conducting heat, generated in said phosphor screen by said high intensity electron beam, away from said phosphor screen;

whereby the arrangement allows a very high intensity electron beam to be used in the cathode ray tube without permitting the electron beam to impinge upon and heat said faceplate and without any risk of overheating or burning of said phosphor screen.

2. A projection cathode ray tube according to claim 1, wherein said cooling means is the thermal path from said phosphor screen to said metal plate-like member and thence to a heat-absorbing medium comprising free air.

3. A projection cathode ray tube according to claim 1, wherein said cooling means is the thermal path from said phosphor screen to said metal plate-like member and thence to a heat-absorbing medium comprising a moving cooling fluid.

4. A projection cathode ray tube according to claim 2 or 3, wherein said cooling means comprises at least one metal fin located exteriorly of said metal plate-like member and in heat exchange relation therewith to enhance the extraction of heat from said metal plate-like member.

5. A projection cathode ray tube according to claim 3, wherein said moving cooling fluid is air or another gaseous coolant.

6. A projection cathode ray tube according to claim 3, wherein said moving cooling fluid is water or another liquid coolant.

7. A projection cathode ray tube according to claim 3, wherein said cooling means comprises at least one duct traversing at least a portion of the expanse of said metal plate-like member in heat exchange relation therewith for guiding said moving cooling fluid past said metal plate-like member for extracting heat therefrom.

8. A projection cathode ray tube according to claim 7, wherein said at least one duct has at least a portion thereof located interiorly of said metal plate-like member.

9. A projection cathode ray tube according to claim 7, wherein said metal plate-like member has a second surface, and said at least one duct has at least a portion thereof located exteriorly of said metal plate-like member and in thermal transfer contact with said second surface of the metal plate-like member.

10. A system for generating a projected high resolution, high light output field sequential video monochrome image, comprising:

a single-gun projection cathode ray tube as claimed in claim 1, wherein said phosphor screen is composed of a monochrome phosphor and develops a monochrome optical image;

a display screen located exteriorly of said cathode ray tube transverse to the path of projection of said optical image through said faceplate of said cathode ray tube; and

a lens system interposed between said faceplate of said cathode ray tube and said display screen for focusing the projected optical image onto said display screen.

11. A system for generating a projected high resolution, high light output field sequential video color image, comprising:

a single-gun projection cathode ray tube as claimed in claim 1, wherein said phosphor screen is composed of a monochrome phosphor and develops a monochrome optical image;

a display screen located exteriorly of said cathode ray tube transverse to the path of projection of said optical image through said faceplate of said cathode ray tube;

a lens system interposed between said faceplate of said cathode ray tube and said display screen for focusing the projected optical image onto said display screen; and

means associated with said cathode ray tube for converting said monochrome optical image to a field sequential color image.

12. A system according to claim 11, wherein said converting means comprises:

(a) a motor-driven rotating color wheel positioned exteriorly of said cathode ray tube between said faceplate of the latter and said display screen;

(b) multiplexer means for selectively applying red, blue and green video chroma signals to said control grid; and

(c) means for sensing the instantaneous rotational position of said color wheel and applying a resultant output signal to said multiplexer means for correspondingly and in synchronism with said rotating color wheel controlling the video signals applied by said multiplexer means to said control grid.

13. A system according to claim 11, wherein said converting means comprises:

(a) a liquid crystal shutter constituting a red, blue and green color filter, said liquid crystal shutter being positioned in the path of projection of said monochrome optical image from said first surface of said metal plate-like member to said display screen;

(b) multiplexer means for selectively applying red, blue and green video chroma signals to said control grid; and

(c) means for sensing the instantaneous red, blue or green color filter state of said liquid crystal shutter and applying a resultant output signal to said multiplexer means for correspondingly and in synchronism with said liquid crystal shutter controlling the video signals applied by said multiplexer means to said control grid.

14. A system according to claim 11, 12 or 13, wherein said cooling means in said cathode ray tube is the thermal path from said phosphor screen to said metal plate-like member and thence to a heat-absorbing medium comprising free air.

15. A system according to claim 14, wherein said cooling means in said cathode ray tube comprises at least one metal fin located exteriorly of said metal plate-like member and in heat exchange relation therewith to enhance the flow of heat from said metal plate-like member to said heat-absorbing medium.

16. A system according to claim 11, 12 or 13, wherein said cooling means in said cathode ray tube is the thermal path from said phosphor screen to said metal plate-like member and thence to a heat-absorbing medium comprising a moving cooling fluid.

17. A system according to claim 16, wherein said cooling means in said cathode ray tube comprises at least one metal fin located exteriorly of said metal plate-like member and in heat exchange relation therewith to enhance the flow of heat from said metal plate-like member to said heat-absorbing medium.

18. A system according to claim 17, wherein said moving cooling fluid is air or another gaseous coolant.

19. A system according to claim 17, wherein said moving cooling fluid is water or another liquid coolant.

20. A system according to claim 17, wherein said cooling means comprises at least one duct traversing at least a portion of the expanse of said metal plate-like member in heat exchange relation therewith for guiding said moving cooling fluid past said metal plate-like member for extracting heat therefrom.

21. A system according to claim 20, wherein said at least one duct has at least a portion thereof located interiorly of said metal plate-like member.

22. A system according to claim 20, wherein said metal plate-like member has a second surface, and said at least one duct has at least a portion thereof located exteriorly of said metal plate-like member and in thermal transfer contact with said second surface of the latter.