Shuttered and cycled light emitting diode display and method of producing the same

• US 5,359,345 A
• Filed: 08/05/1992
• Issued: 10/25/1994
• Est. Priority Date: 08/05/1992
• Status: Expired due to Term

• Current Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Original Assignee: Cree Research, Inc. (Wolfspeed, Inc.)
• Inventors: Hunter, C. Eric
• Primary Examiner(s): Oberley, Alvin E.
• Assistant Examiner(s): Liang, Regina
• Application Number:
  US07/926,035
• Time in Patent Office: 811 Days
• Field of Search: 340/784 AL, 340/784 G, 340/762, 340/782, 340/701, 340/702, 340/703, 359/48, 359/39, 359/49, 345/102, 345/82, 345/46, 345/83, 357/17
• 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, 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 source adjacent the liquid crystal pixel for emitting light through the liquid crystal pixel, and means 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 sources 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 method of producing a high resolution, high intensity, full color display that is particularly useful for a flat display, comprising the steps of:

sequentially and cyclically 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, the blue LED being formed in silicon carbide and being selected from the group having a peak emission at a wavelength ranging between about 424-428 nanometers, about 455-460 nanometers, about 465-470 nanometers, and about 475-480 nanometers so that a high intensity blue light source is thereby provided; and

shuttering the set of LEDs with only a portion of a liquid crystal pixel for at least a portion of the sequential predetermined time periods to thereby emit light from the shuttered portion of the liquid crystal pixel for a selected time period from each of the red, green, and blue LEDs so that the light emitted from the portion of 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 portion of 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 rather than as a sequential appearance of those colors.

2. A method of producing a high resolution, high intensity full color display according to claim 1, further comprising the step of:

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

3. A method of producing a high resolution, high intensity, full color display according to claim 2, further comprising the step of:

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

4. A method of producing a high resolution, high intensity, full color display according to claim 1 wherein one cycle is less than the amount of time that the human eye can detect changes in colors.

5. A method of producing a high resolution, high intensity, full color display according to claim 1, wherein one cycle is generally less than 1/60th of a second.

6. A method of producing a high resolution, high intensity, full color display according to claim 1, wherein the predetermined time period is generally less than 1/180th of a second.

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

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

sequentially and cyclically lighting a 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, the blue LED being formed of silicon carbide and being selected from the group having a peak emission at a wavelength ranging between about 424-428 nanometers, about 455-460 nanometers, about 465-470 nanometers, and about 475-480 nanometers so that a high intensity blue light source is thereby provided;

addressing individually a portion of a liquid crystal pixel a plurality of times during each sequential predetermined time period in response to the received data;

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

shuttering the set of LEDs with only the individual portion of the liquid crystal pixel for at least a portion of the sequential predetermined time periods in response to the received data to thereby emit light from the shuttered portion of the pixel for a selected time period from each of the red, green, and blue LEDs so that the light emitted from the portion of 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 portion of 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 rather than as a sequential appearance of those colors.

8. A method of producing a high resolution, high intensity, full color display according to claim 7 wherein one cycle is generally less than 1/60th of a second.

9. A method of producing a high resolution, high intensity, full color display according to claim 7, wherein said predetermined time period is generally less than 1/180th of a second.