LIQUID CRYSTAL DISPLAY APPARATUS

• US 20110012937A1
• Filed: 07/15/2010
• Published: 01/20/2011
• Est. Priority Date: 07/17/2009
• Status: Abandoned Application

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: KOBAYASHI, Takahiro, ONISHI, Toshiki
• Application Number:
  US12/837,289
• Publication Number:
  US 20110012937A1
• Time in Patent Office: Days
• US Class Current: 345/690
• CPC Class Codes: G09G 2320/0242 Compensation of deficiencies in the appearance of colours
• CPC Class Codes: G09G 2320/0633 by amplitude modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix

Abstract

A liquid crystal display apparatus that can alter the chromaticity of a display image in a white backlight by performing a drive control of light sources. The liquid crystal display apparatus (100) has: a liquid crystal panel (101) that displays images; a backlight (102) that has semiconductor light sources (106) and that illuminates the liquid crystal panel (101); a driving section (103) that drives the semiconductor light sources (106); a controlling section (104) that controls the driving section (103) so as to realize a desired, temporally-averaged chromaticity by switching between a plurality of chromaticities per switching time; and a signal brightness level detecting section (105) that detects the feature amount of an image. The controlling section (104) controls at least one of the chromaticity and brightness according the feature amount detected in signal brightness level detecting section (105).

Claims

1. A liquid crystal display apparatus comprising:

a liquid crystal panel that displays an image;

a backlight that comprises a semiconductor light source and that illuminates the liquid crystal panel;

a driving section that drives the semiconductor light source;

a controlling section that controls the driving section so as to realize a desired, temporally-averaged chromaticity by switching between a plurality of chromaticities per switching time; and

a detecting section that detects a feature amount of at least one of the image, the semiconductor light source and ambient light,

wherein the controlling section controls at least one of chromaticity and brightness according to the feature amount detected by the detecting section.

2. The liquid crystal display apparatus according to claim 1, wherein the semiconductor light source is a light emitting diode.

3. The liquid crystal display apparatus according to claim 1, wherein the semiconductor light source is a semiconductor laser.

4. The liquid crystal display apparatus according to claim 2, wherein the light emitting diode is a white light emitting diode.

5. The liquid crystal display apparatus according to claim 1, wherein the plurality of chromaticities are realized by driving the semiconductor light source by a drive pulse formed by combining a plurality of pulses of different current values.

6. The liquid crystal display apparatus according to claim 5, wherein switching times are identical for all of the plurality of pulses.

7. The liquid crystal display apparatus according to claim 6, wherein duty cycles are identical for all of the plurality of pulses except for a pulse having a current value of zero.

8. The liquid crystal display apparatus according to claim 1, wherein a sum of switching times for the plurality of chromaticities is twenty milliseconds or less.

9. The liquid crystal display apparatus according to claim 5, wherein, to change the desired chromaticity, the controlling section performs a brightness maintaining control for maintaining a constant average brightness of the backlight.

10. The liquid crystal display apparatus according to claim 9, wherein the brightness maintaining control changes only each current value of the plurality of pulses.

11. The liquid crystal display apparatus according to claim 5, wherein, to change brightness, the controlling section performs a chromaticity maintaining control for maintaining a constant chromaticity.

12. The liquid crystal display apparatus according to claim 11, wherein the chromaticity maintaining control changes duty cycles of the plurality of pulses at a uniform rate, according to a pulse width modulation scheme.

13. The liquid crystal display apparatus according to claim 1, wherein the controlling section controls a color temperature of the backlight lower when an average brightness level of the image is lower, and controls the color temperature of the backlight higher when the average brightness level of the image is higher.

14. The liquid crystal display apparatus according to claim 1, wherein the controlling section controls brightness of the backlight lower when an average brightness level of the image is lower, and controls the brightness of the backlight higher when the average brightness level of the image is higher.

15. The liquid crystal display apparatus according to claim 1, wherein the controlling section controls a color temperature of the backlight lower when a brightness level of the ambient light is lower, and controls the color temperature of the backlight higher when the brightness level of the ambient light is higher.