High resolution, high brightness light emitting diode display and method and producing the same

• US 5,724,062 A
• Filed: 09/21/1994
• Issued: 03/03/1998
• Est. Priority Date: 08/05/1992
• Status: Expired due to Term

• Current Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Original Assignee: Cree Research, Inc.
• Inventors: Hunter, C. Eric
• Primary Examiner(s): LIANG, REGINA
• Application Number:
  US08/310,260
• Time in Patent Office: 1,259 Days
• Field of Search: 345/102, 345/46, 345/82, 345/83, 345/207, 359/48, 359/39, 359/49
• US Class Current: 345/102
• CPC Class Codes: G02F 1/133622 Colour sequential illumination
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336

Abstract

A high resolution, high brightness, full color display is provided having a liquid crystal pixel selectably addressable during a predetermined time period, a set of at least one red, one green, and one blue color light emitting diodes positioned adjacent the liquid crystal pixel for emitting light through the liquid crystal pixel, and means connected to the liquid crystal pixel for addressing the liquid crystal pixel a plurality of times during the predetermined time period for each color so as to provide persistence when changes in color are perceived by the human eye. A method of producing a high resolution, full color display is also provided by lighting a set of one red, one green, and one blue light emitting diodes by lighting the respective colored light sources for a predetermined time period for each color and shuttering the set of light sources with a liquid crystal pixel for at least a portion of the predetermined time period to thereby emit light from the shuttered pixel for a selected time period so as to provide persistence when changes in color are perceived by the human eye.

Claims

1. A high resolution, full color display, comprising:

a liquid crystal pixel selectably addressable during a predetermined time period wherein said liquid crystal pixel comprises an array of individual portions of a liquid crystal pixel and wherein each individual portion of said pixel is individually addressable over the predetermined time period;

an interspersed set of at least one red, one green, and one blue color light emitting diodes positioned adjacent said liquid crystal pixel and adapted for emitting light through said liquid crystal pixel; and

means connected to said liquid crystal pixel for selectably addressing the liquid crystal pixel a plurality of times during the predetermined time period so as to provide persistence when changes in color occur.

2. A high resolution, high brightness, full color display as defined by claim 1, wherein said liquid crystal pixel is selectably addressable for an amount of time generally less than the amount of time that the human eye can detect changes in colors.

3. A high resolution, high brightness, full color display as defined by claim 1 further comprising:

means connected to safe interspersed set of LEDs for lighting said interspersed set of LEDs by respective red, green, and blue colors for a predetermined time period for each color.

4. A high resolution, high brightness, full color display according to claim 1, further comprising:

means connected to said set of LEDs and said liquid crystal pixel for synchronizing the lighting of said interspersed set of LEDs with the means for addressing said individual liquid crystal pixel a plurality of times during the predetermined time period.

5. A high resolution, high brightness, full color display according to claim 1, further comprising means positioned between said LEDs and said LCD for measuring the intensity of said LEDs during a time interval.

6. A high resolution, high brightness, full color display according to claim 1, further comprising means positioned between said set of LEDs and said liquid crystal pixel for diffusing the light emitted from said set of LEDs to said liquid crystal pixel.

7. A high resolution, high brightness, full color display as defined by claim 1, wherein said blue LED is formed of gallium nitride.

8. A high resolution, high brightness, full color display as defined by claim 1, wherein said array of LEDs are formed in a single semiconductor substrate.

9. A method of producing a high resolution, high brightness, full color display that is particularly useful for a flat display, comprising the steps of:

lighting a set of one red, one green, and one blue LEDs by lighting the respective LEDs in the set for a predetermined time period for each LED in which one cycle is defined by the sum of the predetermined time periods, and in which one cycle is a time period less than that for which the sequential lighting of the LEDs can be detected by the human eye; and

shuttering the set of LEDs with a liquid crystal pixel which comprises an array of individual portions of a liquid crystal pixel for at least a portion of the predetermined time periods to thereby emit light from the shuttered pixel for a selected time period from each of the red, green, and blue LEDs so that the light emitted from the pixel is an emission of red, green, and blue light, each for a time period less than or up to the predetermined time period so that the emission from the pixel during each cycle is defined by the amount of time a light pulse from each LED is shuttered and will normally be perceived by a human eye as a blend of the colors emitted by the respective LEDs.

10. A method as defined by claim 9, further comprising the step of:

selectably addressing the liquid crystal pixel a plurality of address times during each predetermined time period.

11. A method as defined by claim 10, further comprising the step of:

synchronizing the addressing of the liquid crystal pixel with the lighting of the set of red, green, and blue LEDs.

12. A method as defined by claim 9, wherein one cycle is less than the amount of time that the human eye can detect changes in colors.

13. A method as defined by claim 9, wherein one cycle is generally less than 1/60th of a second.

14. A method as defined by claim 9, wherein the predetermined time period is generally less than 1/180th of a second.

15. A method of producing a high resolution, high brightness, full color display that is particularly useful for a flat display, comprising the steps of:

transmitting data to the display to be represented during a predetermined time period;

receiving the data to be represented for display during the predetermined time period;

sequentially and cyclically lighting an interspersed set of red, green, and blue LEDs in response to the received data by lighting the respective LEDs in the set for a predetermined time period for each color, in which one cycle is defined by the sum of the predetermined time periods, and in which one cycle is a time period less than that for which the sequential lighting of the LEDs can be detected by the human eye;

addressing individually the liquid crystal pixels in a set of liquid crystal pixels wherein at least one of said liquid crystal pixels comprises an array of individual portions of a liquid crystal pixel and wherein a liquid crystal pixels in the set of liquid crystal pixels is addressed individually a plurality of address times during each sequential predetermined time period in response to said received data;

synchronizing the addressing of the individual liquid crystal pixels with the sequentially and cyclically lighting of the set of red, green, and blue LEDs; and

shuttering the set of LEDs with individual pixels in the set of liquid crystal pixels for at least a portion of the sequential predetermined time periods in response to said received data to thereby emit light from the shuttered pixels for a selected time period from each of the red, green, and blue LEDs so that the light emitted from the pixel is a sequential emission of red, green, and blue light, each for a time period less than or up to the predetermined time period so that the emission from the pixels during each cycle is defined by the amount of time a light pulse from each LED is shuttered and will normally be perceived by a human eye as a blend of the colors emitted by the respective LEDs rather than as a sequential appearance of those colors.

16. A method as defined by claim 15, wherein one cycle is generally less than 1/60th of a second.

17. A method as defined by claim 15, wherein said predetermined time period is generally less than 1/180th of a second.