LIQUID CRYSTAL DISPLAY SYSTEM AND METHOD

• US 20100060672A1
• Filed: 11/02/2007
• Published: 03/11/2010
• Est. Priority Date: 11/09/2006
• Status: Active Grant

• Current Assignee: Koninklijke Philips N.V.
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Van Beek, Wilhelmus Henricus Maria, Hoppenbrouwers, Jurgen Jean Louis, Jak, Martin Jacobus Johan
• Granted Patent: US 9,805,666 B2
• Time in Patent Office: Days
• US Class Current: 345/690
• CPC Class Codes: G09G 2320/0646 Modulation of illumination source brightness and image signal correlated to each other
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• 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 display system (1) for generating a picture in accordance with image information (10) derived from a video signal has a light modulation device (20), an illumination device (30) and a control circuit (40) for driving both devices. The algorithm implemented in the control circuit (40) distributes the image information (10) over the light modulation device (20) and the illumination device (30) in order to minimize the power consumption of the display system.

Claims

1. A display system (1) for generating a picture in accordance with image information (10) derived from a video signal, comprising:

A light modulation device (20) having a multitude of pixels (21) with variable transmission,

An illumination device (30) for illuminating the light modulation device,

A control circuit (40), for driving both the light modulation device and the illumination device,

The light modulation device, when in operation, having at least one region in which a pixel P_{Lregionmax, i} exhibits the largest luminance in accordance with the image information (10) for said region,

characterized in that

The control circuit is arranged to distribute the image information over the light modulation device and the illumination device by

Setting the transmission of pixel P_{Lregionmax, i} to its maximum,

Setting the luminance L_BL,i of the illumination device (30) behind said region in accordance with the luminance of pixel P_{Lregionmax, i},

Adjusting the transmission of the other pixels (21) in said region in accordance with the image information (10) and L_BL,i.

2. A display system (1) for generating a picture in accordance with image information (10) derived from a video signal, comprising:

A light modulation device (20) having a multitude of pixels (21) with variable transmission,

An illumination device (30) for illuminating the light modulation device,

A control circuit (40), for driving both the light modulation device and the illumination device,

The light modulation device, when in operation, having at least one region in which a pixel P_{Lregionmax, i} exhibits a luminance L_{pic, regionmax, i} and having a pixel P_Lmax exhibiting the largest luminance L_{pic, max} of the display system (1) in accordance with the image information (10),

characterized in that

The control circuit is arranged to distribute the image information over the light modulation device and the illumination device by

Selecting a parameter a from the range ½

<

a≦

1 dependent on the luminance level(s) L_{pic, regionmax, i}

Setting the luminance L_BL,i of the illumination device (30) behind said at least one region according to the formula

$L_{\mathrm{BL},i}=L_{\mathrm{pic},\max }\times <br><br>{\left[\frac{L_{\mathrm{pic},\mathrm{region}<br><br><br><br>\max ,i}}{L_{\mathrm{pic},\max }}\right]}^a,$

Adjusting the transmission of the other pixels (21) in said region in accordance with the image information (10) and L_BL,i.

3. A display system according to claim 2, wherein the control circuit (40) is arranged to selecting the parameter a=1 for luminance levels L_{pic, regionmax, i} above a predetermined threshold.

4. A display system according to claim 3, wherein the predetermined threshold level is chosen to lie in the range 2%-10% of the maximum L_{pic, max} achievable on said display system.

5. A method to minimize a power consumption of a display system (1) for generating a picture in accordance with image information (10) derived from a video signal, the display system comprising:

A light modulation device (20) having a multitude of pixels (21) with variable transmission,

An illumination device (30) for illuminating the light modulation device,

A control circuit (40), for driving both the light modulation device and the illumination device,

The method comprising the step of distributing the image information (10) over the light modulation device (20) and the illumination device (30) by;

Dividing the light modulation device (20) in at least one region,

Determining for each of the at least one regions a pixel P_{Lregionmax, i} exhibiting the largest luminance L_{pic,regionmax, i},

Setting the transmission of each pixel P_{Lregionmax, i} to its maximum,

Setting the luminance L_BL,i of the illumination device (30) behind each of said regions in accordance with L_{pic,regionmax, i},

Adjusting the transmission of the other pixels (21) in each of said regions in accordance with the image information (10) and L_BL,i.

6. A method to minimize a power consumption of a display system (1) for generating a picture in accordance with image information (10) derived from a video signal, the display system comprising:

A light modulation device (20) having a multitude of pixels (21) with variable transmission,

An illumination device (30) for illuminating the light modulation device,

A control circuit (40), for driving both the light modulation device and the illumination device,

The method comprising the step of distributing the image information (10) over the light modulation device (20) and the illumination device (30) by;

Dividing the light modulation device (20) in at least one region,

Determining for each of the at least one regions a pixel P_{Lregionmax, i} exhibiting the largest luminance L_{pic,regionmax, i},

Determining a pixel P_Lmax exhibiting the largest luminance L_{pic, max} of the

display system (1) in accordance with the image information (10),

Selecting a parameter a from the range ½

a≦

1 dependent on the luminance level(s) L_{pic, regionmax, i}

Setting the luminance L_BL,i of the illumination device (30) behind said at least one region according to the formula

$L_{\mathrm{BL},i}=L_{\mathrm{pic},\max }\times <br><br>{\left[\frac{L_{\mathrm{pic},\mathrm{region}<br><br><br><br>\max ,i}}{L_{\mathrm{pic},\max }}\right]}^a,$

Adjusting the transmission of the other pixels (21) in said region in accordance with the image information (10) and L_BL,i.

7. A method according to claim 6, further comprising the steps of

Setting the parameter a=1 for luminance levels L_{pic, regionmax, i} above a predetermined threshold.