Image projection system employing a cold cathode field-emission image source

• US 5,194,884 A
• Filed: 01/13/1992
• Issued: 03/16/1993
• Est. Priority Date: 04/08/1991
• Status: Expired due to Term

• Current Assignee: Motorola Solutions, Inc.
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Parker, Norman W., Kane, Robert C.
• Primary Examiner(s): Cuchlinski, Jr, William A.
• Assistant Examiner(s): Dowling, William C.
• Application Number:
  US07/819,752
• Time in Patent Office: 428 Days
• Field of Search: 353/77, 353/98, 353/99, 353/122, 358/231, 358/230, 358/60, 313/309, 313/336
• US Class Current: 353/122
• CPC Class Codes: G03B 21/00 Projectors or projection-type viewers; Accessories therefor devices for changing pictures G03B23/00
• CPC Class Codes: H01J 31/127 using large area or array sources, i.e. essentially a source for each pixel group
• CPC Class Codes: H04N 5/7408 Direct viewing projectors, e.g. an image displayed on a video CRT or LCD display being projected on a screen

Abstract

An image projection system utilizing a cold cathode field emission device to provide the image source is provided. By using a cold cathode field emission device as an image source, an improved image may be achieved as compared to that of a conventional electron-gun CRT image source. First, the resulting image provides improved resolution, due to the fact that smaller pixel cells may be achieved with the cold cathode device. Second, the resulting image is considerably brighter, due to the fact that much higher current densities are achievable with a cold cathode image unit, as compared to the older electron-gun CRT unit.

Claims

1. An image projection system comprising:

source means for providing an image, said source means including a cold cathode field emission device that sources a non-scanning stream of electrons,

a plurality of electron emitters for emitting electrons,

a faceplate on which is disposed a layer of cathodoluminescent material distally disposed with respect to the electron emitters by an interelectrode spacing of at least 2 millimeters,

a voltage source operable coupled to the faceplate and providing a voltage of at least 10,000 volts,

projection means for projecting said image on a display device.

2. The image projection system of claim 1 wherein said projection means includes a mirror.

3. The image projection system of claim 2 wherein said display device includes a viewing screen.

4. The image projection system of claim 3, said viewing screen including a front side, the front side facing said mirror, said image projection system arranged for viewing from said front side.

5. The image projection system of claim 3, said viewing screen including a rear side, the rear side facing away from said mirror, said image projection system arranged for viewing from said rear side.

6. The image projection system of claim 1 wherein said projection means includes a lense.

7. The image projection system of claim 6 wherein said display device includes a viewing screen.

8. The image projection system of claim 7, said viewing screen including a front side, the front side facing said mirror, said image projection system arranged for viewing from said front side.

9. The image projection system of claim 7, said viewing screen including a rear side, the rear side facing away from said mirror, said image projection system arranged for viewing from said rear side.

10. The image projection system of claim 1 wherein each of the plurality of electron emitters may be selectively energized so as to provide emitted electrons to impinge on a selected part of the faceplate.