Control and drive circuit arrangement for illumination performance enhancement with LED light sources

• US 20020070914A1
• Filed: 12/12/2000
• Published: 06/13/2002
• Est. Priority Date: 12/12/2000
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Philips Electronics North America Corporation (Koninklijke Philips N.V.)
• Inventors: Chang, Chin, Bruning, Gert W.
• Granted Patent: US 6,888,529 B2
• Time in Patent Office: Days
• US Class Current: 345/102
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• 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 2320/041 Temperature compensation
• CPC Class Codes: G09G 2320/062 Adjustment of illumination source parameters
• CPC Class Codes: G09G 2320/064 by time modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2320/0666 for control of colour parameters, e.g. colour temperature
• CPC Class Codes: G09G 3/3413 Details of control of colour illumination sources
• CPC Class Codes: H05B 45/22 using optical feedback
• CPC Class Codes: H05B 45/28 using temperature feedback
• CPC Class Codes: H05B 45/385 using flyback topology
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

A backlight for an LCD display comprised of an array of LEDs. The backlight may be driven and controlled by a fast pulse power converter, thus providing a response time for the backlight on the order of microseconds. The backlight may thus be used for image display, for example, in the depiction of images in a video input to the LCD and removal of image artifacts.

Claims

1. A LED backlight for an LCD display, the backlight comprised of an array of LEDs and LED drive and control circuitry.

2. The backlight as in claim 1, wherein the array of LEDs provide the color output for the pixels for the displayed image of the LCD.

3. The backlight as in claim 2, wherein the pixels of the LCD are not color filtered.

4. The backlight as in claim 3, wherein the LED backlight provides red, green and blue light to the LCD display in a repeating cycle, LCD pixels of the display being addressed to transmit the amount of red, green and blue light in the portion of the image corresponding to the pixels.

5. The backlight as in claim 1, wherein the drive and control circuitry regulates at least one of the color point and color content of the light output of the LED backlight.

6. The backlight as in claim 1, wherein the drive and control circuitry comprises a power regulated converter with control electronics.

7. The backlight as in claim 6, wherein the power regulated converter is a fast pulse converter.

8. The backlight as in claim 7, wherein the fast pulse converter has a response time on the order of microseconds.

9. The backlight as in claim 1, wherein the array of LEDs is comprised of sub-arrays of red, green and blue LEDs, the drive circuitry regulating the light output of each sub-array independently of the others.

10. The backlight as in claim 9, wherein the pixels of the sub-arrays are interspersed in a two-dimensional plane.

11. The backlight as in claim 9, wherein the sub-arrays are comprised of one or more regions of contiguous pixels of the same color.

12. The backlight as in claim 9, wherein the drive circuitry receives as input reference signals corresponding to the red, green and blue light output of the backlight, the reference signals being used by the drive circuitry to drive the respective red, green and blue sub-arrays to output red, green and blue light corresponding to the respective input reference signals.

13. The backlight as in claim 12, wherein the reference signals received reflect at least part of an image to be displayed.

14. The backlight as in claim 13 wherein the reference signals received are frames of a video signal and its color and intensity content.

15. The backlight as in claim 9, wherein the drive circuitry independently regulates the light output of each sub-array to create a backlight having at least one of a color point and color temperature that is a function of an image displayed by the LCD display.

16. The backlight as in claim 15, wherein the image is at least one frame of a video displayed on the LCD display.

17. The backlight as in claim 9, wherein the drive circuitry is comprised of a separate controller for the LEDs of each sub-array.

18. The backlight as in claim 17, wherein each controller for the LEDs of each sub-array controls at least one switch that regulates the current to one or more LEDs of the sub-array.

19. The backlight as in claim 9, wherein the drive circuitry is comprised of at least one controller that provides independent control signals for the LEDs of each sub-array.

20. The backlight as in claim 19, wherein the at least one controller provides control signals that control at least one switch that regulates the current to one or more LEDs of the sub-array.

21. The backlight as in claim 9, wherein the drive circuitry creates at least one of a pulse amplitude modulation of the current input to the LEDs in the sub-arrays, a pulse width modulation of the current input to the LEDs in the sub-arrays and a pulse frequency modulation of the current input to the LEDs in the sub-arrays.

22. The backlight as in claim 21, wherein the at least one of a pulse amplitude modulation of the current input to the LEDs in the sub-arrays, a pulse width modulation of the current input to the LEDs in the sub-arrays and a pulse frequency modulation of the current input to the LEDs in the sub-arrays includes a dc current bias.

23. The backlight as in claim 1, wherein the LED backlight is comprised of at least one LED module comprised of LEDs of one color.