Liquid crystal display unit which is back-lit with colored lights

• US 5,128,782 A
• Filed: 05/10/1990
• Issued: 07/07/1992
• Est. Priority Date: 08/22/1989
• Status: Expired due to Term

• Current Assignee: Acacia Patent Acquisition Corporation (Acacia Research Corporation)
• Original Assignee: Lawson A. Wood
• Inventors: Wood, Lawson A.
• Primary Examiner(s): Hille, Rolf
• Assistant Examiner(s): TRAN, MINH LOAN
• Application Number:
  US07/521,399
• Time in Patent Office: 789 Days
• Field of Search: 350/345, 350/333, 350/339 F, 350/339 D, 350/331 R, 350/332 R, 350/339 R, 358/236, 358/237, 358/241, 340/784 G, 340/784 E, 340/784 A
• US Class Current: 349/61
• CPC Class Codes: G02F 1/133621 providing coloured light G02F1/133617, G02F1/133533 take precedence
• CPC Class Codes: G02F 1/133622 Colour sequential illumination
• CPC Class Codes: G09G 2300/0426 Layout of electrodes and connections
• CPC Class Codes: G09G 2300/0439 Pixel structures
• CPC Class Codes: G09G 2310/0205 Simultaneous scanning of several lines in flat panels
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• 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 2310/0281 Arrangement of scan or data electrode driver circuits at the periphery of a panel not inherent to a split matrix structure
• CPC Class Codes: G09G 2310/08 Details of timing specific for flat panels, other than clock recovery
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0261 in the context of movement of objects on the screen or movement of the observer relative to the screen
• CPC Class Codes: G09G 2320/0285 using tables for spatial correction of display data
• CPC Class Codes: G09G 2360/145 the light originating from the display screen
• CPC Class Codes: G09G 3/2022 using sub-frames
• CPC Class Codes: G09G 3/2081 with combination of amplitude modulation and time modulation space and time error diffusion G09G3/2066
• 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
• CPC Class Codes: G09G 3/3622 using a passive matrix G09G3/3674 - G09G3/3696 take precedence
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence

Abstract

A liquid crystal display unit includes a liquid crystal display panel having a matrix or pixels which act as light valves. The red component of an image is displayed on the panel, and a red light is flashed on the back of the panel. Then the green component of the image is displayed and a green light is flashed, and the blue component is displayed and a blue light is flashed. A plurality of light sources, each having a red light emitter, a green light emitter, and a blue light emitter, may be employed at a close distance to an active-matrix LCD panel if compensation is provided for the differences in light intensity at different positions on the back of the panel. A passive-matrix LCD panel may be used if a flash of light is emitted each time a row electrode of the panel is strobed. Preferably a plurality of light sources is used, and after one row electrode is strobed and its associated light source is fired, the next row electrode to be strobed is located adjacent a different light source. As a result, a row of pixels is exposed to an intense burst of light at the optimum moment and a relatively mild burst of light as the row of pixels is turning OFF.

Claims

1. A display unit, comprising:

a panel having a matrix of light valves which provide pixels for displaying an image, the panel additionally having a back side; and

means for exposing the back side of the panel to light having a first color, to light having a second color, and to light having a third color,

wherein the means for exposing includes a first flash tube with a trigger terminal, a second flash tube with a trigger terminal, and a third flash tube with a trigger terminal, the means for exposing additionally including means for establishing a potential difference across the flash tubes, and means connected to the trigger terminals for triggering one of the first, second, and third flash tubes at a time, and

wherein each burst of light has a duration of less than about 0.0001 second.

2. The display unit of claim 1, wherein each burst of light has a duration of less than about 0.00001 second.

3. The display unit of claim 1, wherein the means for exposing further comprises first filter means for filtering light generated by the first flash tube, second filter means for filtering light generated by the second flash tube, and third filter means for filtering light generated by the third flash tube, the first, second, and third filter means having different colors.

4. The display unit of claim 3, further comprising means disposed between the back side of the panel and the first, second, and third filter means for diffusing light.

5. The display unit of claim 3, wherein the first, second, and third filter means comprise first, second, and third filter tubes which are disposed around the first, second, and third flash tubes, respectively.

6. The display unit of claim 1, wherein the panel is an active-matrix LCD panel.

7. The display unit of claim 1, wherein the panel is a passive-matrix LCD panel.

8. A liquid crystal display unit, comprising:

a passive-matrix liquid crystal display panel having a matrix of light valves which provides pixels for displaying an image, the panel additionally having a back side and a plurality of row electrodes;

means for strobing the row electrodes of the display panel in a predetermined sequence; and

means for exposing the back side of the panel to a short duration burst of light each time a row electrode of the display panel is strobed.

9. The liquid crystal display unit of claim 8, wherein the means for exposing comprises at least one first flash tube, first filter means for transmitting only light of a first primary color from the at least one first flash tube, at least one second flash tube, second filter means for transmitting only light of a second primary color from the at least one second flash tube, at least third flash tube, and third filter means for transmitting only light of a third primary color from the at least one third flash tube, and further comprising means for diffusing the light of the three primary colors before the light of the three primary colors reaches the back side of the panel.

10. The liquid crystal display unit of claim 8, wherein the means for exposing comprises a plurality of illuminating means disposed at different positions behind the display panel, and means for actuating the illuminating means in a predetermined sequence, and wherein the predetermined sequence in which the row electrodes are strobed by the means for strobing in such that each row electrode that is strobed is spaced apart by a plurality of intervening row electrodes from the last row electrode that was strobed.

11. A display unit, comprising:

a panel having a matrix of light valves which provide pixels for displaying an image, the panel having a back side;

means for exposing the back side of the panel to short duration bursts of light, the light of each burst varying in intensity in a plane parallel to the back side of the panel; and

means for electronically compensating for the varying light intensity in the plane.

12. The display unit of claim 11, wherein the means for exposing comprises a light source having first illuminating means for generating short duration bursts of light having a first color, second illuminating means for generating short duration bursts of light having a second color, and third illuminating means for generating short duration bursts of light having a third color, the back side of the panel being exposed to light of only one color at a time.

13. The display unit of claim 12, wherein the first illuminating means comprises a flash tube having a trigger terminal, wherein the second illuminating means comprises another flash tube having a trigger terminal, and wherein the third illuminating means comprises an additional flash tube having a trigger terminal.

14. The display unit of claim 12, wherein the means for exposing further comprises at least one additional light source having first, second, and third additional illuminating means for respectively generating short duration bursts of light having the first color, the second color, and the third color.

15. The display unit of claim 14, wherein the means for electronically compensating comprises means for controlling the density of the pixels depending at least in part on whether a burst of light has the first color, the second color, or the third color.

16. The display unit of claim 11, wherein the means for electronically compensating comprises means for controlling the density of the pixels.

17. The display unit of claim 11, wherein the light valves are liquid crystal light valves, and the panel is an active-matrix LCD panel.

18. A display unit, comprising:

a panel having a plurality of row electrodes and having a matrix of light valves which provide pixels for displaying an image, the light valves being normally closed and being disposed in rows cooperating with the row electrodes so as to permit display of corresponding lines of the image when respective row electrodes are strobed, at least one row of light valves being aligned with each row electrode, the panel additionally having a back side;

means for conveying video information to the panel, the means for conveying including means for strobing the row electrodes in a predetermined sequence; and

means for exposing the back side of the panel to a short duration burst of light each time a row electrode is strobed.

19. The display unit of claim 18, wherein the means for exposing comprises a light source having first illuminating means for generating short duration bursts of light having a first color, second illuminating means for generating short duration bursts of light having a second color, and third illuminating means for generating short duration bursts of light having a third color, the back side of the panel being exposed to light of only one color at a time.

20. The display unit of claim 19, wherein the first illuminating means comprises a flash tube having a trigger terminal, wherein the second illuminating means comprise another flash tube having a trigger terminal, and wherein the third illuminating means comprises an additional flash tube having a trigger terminal.

21. The display unit of claim 19, wherein the predetermined sequence of strobing the row electrodes is such that each row electrode that is strobed is spaced apart by a plurality of intervening row electrodes from the immediately preceding row electrode that was strobed.

22. The display unit of claim 19, wherein the means for exposing further comprises at least one additional light source having first, second, and third additional illuminating means for respectively generating short duration bursts of light having the first color, the second color, and the third color, and wherein the predetermined sequence of strobing the row electrodes is such that each row electrode that is strobed is spaced apart by a plurality of intervening row electrodes from the immediately preceding row electrode that was strobed, each at least one row of light valves that is aligned with a row electrode that is strobed receiving a burst of light from a different light source than the light source that emitted the immediately preceding burst of light.

23. The display unit of claim 22, wherein the means for exposing further comprises means for controlling the total amount of light emitted during a burst as a function of a distance between a row electrode that is strobed and the illuminating means that emits a burst of light to expose the at least one row of light valves aligned with that row electrode.

24. The display unit of claim 23, wherein the means for controlling comprises a memory which stores valves which determine the total amount of light to be emitted during a burst.

25. The display unit of claim 23, wherein the means for controlling comprises a memory which stores valves determining the total amount of light to be emitted during a burst and determining which illuminating means is to emit the burst.

26. The display unit of claim 18, wherein the predetermined sequence of strobing the row electrodes is such that each row electrode that is strobed is spaced apart by a plurality of intervening row electrodes from the immediately preceding row electrode that was strobed, and wherein the means for exposing comprises a light source having illuminating means for generating short duration bursts of light and means for controlling the total amount of light emitted during a burst as a function of a distance between a row electrode that is strobed and the illuminating means.

27. The display unit of claim 26, wherein the light valves are liquid crystal light valves, wherein the panel is a passive-matrix LCD panel which includes a plurality of first column electrodes that traverse the row electrodes, and a plurality of second column electrodes that traverse the row electrodes, each first column electrode having lobes positioned at each row electrode and each second column electrode having lobes positioned at each row electrode, and wherein the means for conveying video information comprises LCD driver unit means for strobing the row electrodes and for displaying a plurality of image lines each time a row electrode is strobed, the LCD driver unit means including a first line storage unit which holds a first line of video information and which is connected to the first column electrodes and a second line storage unit which holds an adjacent second line of video information and which is connected to the second column electrodes.

28. The display unit of claim 18, wherein the light valves are liquid crystal light valves, and the panel is a passive-matrix LCD panel.

29. The display unit of claim 28, wherein the passive-matrix LCD column includes column electrodes, the column electrodes having interleaved lobes, the lobes being disposed with respect to the row electrodes in such a manner that more than one row of pixels is actuated each time a row electrode is strobed.

30. A liquid crystal display unit, comprising:

a liquid crystal display panel having a plurality of row electrodes, a plurality of first column electrodes which traverse the row electrodes, and a plurality of second column electrodes which traverse the row electrodes, each first column electrode having lobes positioned at each row electrode and each second column electrode having lobes positioned at each row electrode; and

LCD driver unit means for strobing the row electrodes in a predetermined sequence and for displaying a plurality of image lines each time a row electrode is strobed, the LCD driver unit means including a first line storage unit which holds a first line of video information and which is connected to the first column electrodes and a second line storage unit which holds an adjacent second line of video information and which is connected to the second column electrodes.

31. The liquid crystal display unit of claim 30, wherein the liquid crystal display panel is a passive-matrix panel having a back side, wherein the predetermined sequence in which the row electrodes are strobed is such that each row electrode that is strobed is spaced apart by a plurality of intervening row electrodes from the last row electrode that was strobed, and further comprising means for exposing the back side of the panel to a short duration burst of light each time a row electrode is strobed, the means for exposing including a plurality of illuminating means that are not all activated at once.