Backlighting arrangement for LCD display panel

• US 5,592,193 A
• Filed: 09/18/1995
• Issued: 01/07/1997
• Est. Priority Date: 03/10/1994
• Status: Expired due to Term

• Current Assignee: Chunghwa Picture Tubes Limited
• Original Assignee: Chunghwa Picture Tubes Limited
• Inventors: Chen, Hsing-Yao
• Primary Examiner(s): Hjerpe, Richard
• Assistant Examiner(s): CHANG, KENT WU
• Application Number:
  US08/529,345
• Time in Patent Office: 477 Days
• Field of Search: 345/102, 345/87, 345/88, 348/750, 348/751, 348/758, 359/48-50
• US Class Current: 345/102
• CPC Class Codes: A61B 90/11 with guides for needles or instruments, e.g. arcuate slides or ball joints
• CPC Class Codes: G09G 2310/024 Scrolling of light from the illumination source over the display in combination with the scanning of the display screen
• CPC Class Codes: G09G 3/342 using several illumination sources separately controlled corresponding to different display panel areas, e.g. along one dimension such as lines

Abstract

A video display system includes a passive display panel such as a liquid crystal display (LCD) panel including a first plurality of horizontally aligned transparent conductive scanning electrodes and a second plurality of vertically aligned transparent conductive signal electrodes disposed on opposed surfaces of the panel. Light directed onto the aft surface of the display panel is transmitted through the panel as each horizontal linear array of first scanning electrodes is turned "ON" with the horizontal linear arrays sequentially turned on for vertically scanning the display panel in a step wise manner. Time varying video image information is provided to the vertically aligned electrodes. Liquid crystal display backlighting is provided in the form of a thin, elongated light beam of uniform intensity directed onto the display panel'"'"'s aft surface. The backlighting beam is vertically displaced, such as from top to bottom, in a stepwise manner over the display panel synchronously with the turning "ON" of the horizontal scanning electrodes such that the beam illuminates only the horizontal linear array of the scanning electrodes which is turned "ON" i.e., only that portion of the display panel containing visible video information, for improved video image contrast and more efficient backlighting of the display panel. The scanning back light beam is provided by a partitioned or sectioned light panel, such as a plasma discharge panel (PDP), where the partitions are each aligned with a respective horizontal array of scanning electrodes and sequentially turned "ON" synchronously with actuation of the scanning electrode arrays.

Claims

1. A video display apparatus comprising:

a passive, generally planar color liquid crystal display panel having a plurality of linear, spaced, parallel arrays of video image elements, wherein said arrays of video image elements are vertically scanned in a sequential manner from a first edge of said display panel to a second, opposed edge of said display panel in providing a plurality of spaced, parallel portions of a video image in a sequential manner on said display panel, and wherein a complete scan of said video image elements defines a picture field;

a partitioned planar light panel disposed generally parallel to and spaced from an aft surface of said display panel and including a plurality of linear, elongated arrays of light sources aligned generally parallel to said arrays of video image elements for directing a white light beam on one or more adjacent arrays of video image elements at a given time; and

synchronizing drive means coupled to said display panel and to said light panel for actuating each of said light sources in a sequential manner synchronously with the vertical scanning of said arrays of video image elements for displacing said white light beam over said display panel in a scanning manner for illuminating only that portion of said display panel providing a portion of a video image at a given time, wherein all of said light sources are sequentially scanned within a picture field;

wherein said arrays of video image elements are greater in number than said arrays of light sources, and wherein each array of light sources directs a white light beam onto a plurality of adjacent, spaced arrays of video image elements, and wherein said arrays of video image elements are scanned in a continuous manner at a first constant scan rate and said arrays of light sources are scanned in a continuous manner at a second constant scan rate, and wherein said first scan rate is greater than said second scan rate, and wherein reduced light energy is used by directing a white light beam from a single array of light sources at a given time onto a plurality of video image elements in said display panel.

2. The video display apparatus of claim 1 wherein said light panel is a plasma discharge panel.

3. The video display apparatus of claim 1 wherein said light panel is a vaccuum flourescent panel.

4. The video display apparatus of claim 1 wherein said display panel is a gas discharge panel.

5. The video display apparatus of claim 1 wherein the first edge of said display panel is at an upper portion thereof and the second edge of said display panel is at a lower portion thereof, and wherein said light beam scans said display panel from top to bottom.

6. The video display apparatus of claim 1 further comprising a projection screen disposed adjacent to and aligned with said display panel for displaying a video image on said projection screen.

7. The video display apparatus of claim 1 wherein said light panel is an electroluminescent panel.

8. A display apparatus for providing a video image comprising:

a passive, generally planar color liquid crystal display panel having a plurality of horizontally aligned, vertically spaced, elongated, generally linear arrays of video image elements, wherein said arrays of video image elements are sequentially scanned in a vertical direction from a first edge of said panel to a second, opposed edge of said panel to provide in a timed manner a plurality of vertically spaced, horizontally aligned portions of a video image, and wherein a full image is formed during a complete scan of said video image elements from said first edge to said second edge of said panel, and wherein a complete scan of said video image elements defines a picture field;

a partitioned planar light panel disposed in a parallel, spaced manner from an aft surface of said display panel, wherein said light panel includes a plurality of horizontally aligned, vertically spaced, elongated, generally linear arrays of white light emitting zones, and wherein each of said white light emitting zones directs an elongated, narrow white light beam on an adjacent array of video image elements in said display panel; and

drive means coupled to each of said arrays of video image elements and each of said arrays of white light emitting zones for actuating said arrays of video image elements and said arrays of white light emitting zones in a sequential, timed manner, wherein all of said white light emitting zones are sequentially scanned within a picture field and wherein a plurality of adjacent arrays of video image elements and a single array of white light emitting zones are actuated at a given time, and wherein said adjacent arrays of video image elements and said single array of white light emitting zones actuated at a given time are disposed adjacent one another and are in mutual horizontal alignment such that only that portion of said display panel defined by adjacent linear arrays of video image elements providing a portion of a video image is illuminated by a white light beam at a given time;

wherein said arrays of video image elements are greater in number than said arrays of white light emitting zones, and wherein each array of white light emitting zones directs a white light beam onto a plurality of adjacent, spaced arrays of video image elements, and wherein said arrays of video image elements are scanned in a continuous manner at a first constant scan rate and said arrays of light emitting zones are scanned in a continuous manner at a second constant scan rate with said first scan rate greater than said second scan rate, and wherein reduced light energy is used by directing a white light beam from a single array of light sources at a given time onto a plurality of adjacent, spaced arrays of video image elements in said display panel.

9. The apparatus of claim 8 wherein said display panel is a liquid crystal display panel.

10. The apparatus of claim 8 further comprising projection means disposed adjacent a forward surface of said liquid crystal display panel for providing a projection video display.

11. The apparatus of claim 8 wherein said arrays of video image elements are scanned downwardly from a first upper edge to a second lower edge of said display panel.

12. The apparatus of claim 8 wherein said light panel is a plasma discharge panel, a vacuum fluorescent panel, a gas discharge panel, or an electroluminescent panel.