Display device and luminance control method therefore

• US 9,607,552 B2
• Filed: 08/11/2014
• Issued: 03/28/2017
• Est. Priority Date: 12/17/2013
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: Lim, Kyongho
• Primary Examiner(s): McLoone, Peter D
• Application Number:
  US14/456,526
• Publication Number:
  US 20150170560A1
• Time in Patent Office: 960 Days
• US Class Current: 1/1
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2330/025 Reduction of instantaneous peaks of current
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/3291 in which the data driver supplies a variable data voltage for setting the current through, or the voltage across, the light-emitting elements

Abstract

A display device and a luminance control method therefore are provided. The display device comprises a luminance controller that establishes multiple peak luminance control (PLC) points by equally dividing a PLC curve and limits the luminance at the PLC point corresponding to the highest average pixel level (APL) at the initial luminance as the PLC curve slopes downward.

Claims

1. A display device in which a peak luminance control (PLC) curve defines a maximum luminance of pixels according to an average pixel level (APL) of an input image the display device comprising:

a luminance controller that establishes multiple PLC points by equally dividing a PLC curve and, when the PLC curve is adjusted by a luminance adjustment variable, limits the luminance of the pixels in a first APL section extending from a lowest PLC point to a predetermined PLC point at an adjusted peak luminance for the lowest PLC point of the PLC curve adjusted by the luminance adjustment variable, and limits the luminance of the pixels in a second APL section after the predetermined PLC point at an initial luminance of the PLC curve which is not adjusted by the luminance adjustment variable,

wherein, when a luminance of the display device decreases, the luminance controller adjusts the PLC curve such that the first APL section increases and the second APL section decreases.

2. The display device of claim 1, wherein the luminance controller controls the luminance at the PLC points according to the following Equation:

P′

O=PO×

k

If Pi>

P′

O then P′

i=P′

O

others P′

i=Pi

where P0 is an initial peak luminance, P′

0 is an adjusted peak luminance, i=0, 1, 2, 3, 4, 5, 6, and 7, and k is the luminance adjustment variable which is ranged within 0 to 1.00,

wherein Pi is the initial luminance at the i-th PLC point in the PLC curve, and P′

i is an adjusted luminance at the i-th PLC point in the adjusted PLC curve.

3. The display device of claim 2, wherein the predetermined PLC point is a PLC point with the a lowest APL in an APL section where Pi <

P′

0 is satisfied.

4. The display device of claim 3, wherein two or more PLC points exist in the first APL section.

5. The display device of claim 4, comprising:

a data driver that converts pixel data into a gamma compensation voltage to generate a data voltage, and outputs the data voltage to data lines;

a scan driver that supplies scan pulses synchronized with the data voltage to scan lines; and

a timing controller that transmits the pixel data to the data driver and controls the operation timings of the data driver and scan driver,

wherein the timing controller modulates the gray level of the pixel data based on the PLC curve or adjusts an high-potential pixel power voltage of the pixels or the gamma compensation voltage based on the PLC curve.

6. The display device of claim 5, wherein the display device is an OLED display or a plasma display panel.

7. A luminance control method for a display device, the method comprising:

forming a peak luminance control (PLC) curve that defines a maximum luminance of pixels according to an average pixel level (APL) of an input image;

establishing multiple PLC points by equally dividing the PLC curve; and

when the PLC curve is adjusted by a luminance adjustment variable, limiting the luminance of the pixels in a first APL section extending from a lowest PLC point to a predetermined PLC point at an adjusted peak luminance for the lowest PLC point of the PLC curve adjusted by the luminance adjustment variable, and limiting the luminance of the pixels in a second APL section after the predetermined PLC point at an initial luminance of the PLC curve which is not adjusted by the luminance adjustment variable,

wherein, when a luminance of the display device decreases, the luminance controller adjusts the PLC curve such that the first APL section increases and the second APL section decreases.

8. The method of claim 7, wherein the luminance at the PLC points is controlled according to the following Equation:

P′

O=PO×

k

If Pi>

P′

O then P′

i=P′

O

others P′

i =Pi

where P0 is an initial peak luminance, P′

0 is an adjusted peak luminance, i =0, 1, 2, 3, 4, 5, 6, and 7, and k is the luminance adjustment variable which is ranged within 0 to 1.00,

wherein Pi is the initial luminance at the i-th PLC point in the PLC curve, and P′

i is an adjusted luminance at the i-th PLC point in the adjusted PLC curve.

9. The method of claim 8, comprising:

supplying a high-potential pixel power voltage to the pixels;

converting pixel data into a gamma compensation voltage to generate a data voltage, and outputting the data voltage to data lines;

modulating the gray level of the pixel data based on the PLC curve or adjusting the high-potential pixel power voltage or the gamma compensation voltage based on the PLC curve.