Self-lighting display device and method of driving the same

Patent metadata

Field	Value
Publication number	US-9269301-B2
Application number	US-201314013985-A
Country	US
Kind code	B2
Filing date	Aug 29, 2013
Priority date	May 28, 2013
Publication date	Feb 23, 2016
Grant date	Feb 23, 2016

Abstract

The self-lighting subpixels of a display device are ones whose output luminances are functions of analog drive voltages applied to the subpixels and corresponding digital grayscale command signals used for controlling the subpixels. The display device generates corresponding analog dimming values and digital dimming values in accordance with supplied current limiting parameters and generates control value signals using the analog dimming values and the digital dimming values. It also changes the original grayscale digital data values of input video signals of one frame in accordance with the digital dimming values.

First claim

What is claimed is:

1. A self-lighting type of display device in which output luminance is a function of analog drive voltages and corresponding digital grayscale command signals, the display device comprising:
a frame operation processor configured for generating analog dimming value signals corresponding to to-be-output ones of the analog drive voltages and configured for generating corresponding digital dimming value signals corresponding to to-be-output ones of the digital grayscale command signals, the frame operation processor being responsive to supplied current limiting parameters, the frame operation processor configured for generating control value signals using the generated analog dimming value signals, the digital dimming value signals, and measured values of a current supplied to a plurality of self-lighting sub-pixels;
an image data processor configured for changing initial grayscale digital data values of input video signals of one frame by using the digital dimming values generated by the frame operation processor;
a self-lighting type of display panel including the sub-pixels configured to display an image corresponding to the input video signals of a respective image frame; and
a variable power supply configured for controlling power source voltages used to drive the sub-pixels of the display panel, the power source voltages being controlled in accordance with the control value signals generated by the frame operation processor,
wherein the variable power supply is further configured to measure the values of the current supplied to the sub-pixels and output the measured values of the current to the frame operation processor.

2. The display device of claim 1 , wherein the self-lighting sub-pixels include organic light emitting diodes (OLED's) and the power source voltages comprise first power source voltages supplied to anodes of the organic light emitting diodes of the plurality of sub-pixels and second power source voltages supplied to cathodes of the organic light emitting diodes, and wherein the power supply controls the first power source voltages in accordance with the control value signals generated by the frame operation processor.

3. The display device of claim 1 , wherein the image data processor comprises a digital dimming operator for multiplying the grayscale data of the video signals of the frame by the digital dimming values to change the grayscale data of the video signals.

4. The display device of claim 1 , wherein the control value signals are pulse width modulated (PWM) signals.

5. The display device of claim 1 , wherein the control value signals are digital values for designating corresponding voltage levels.

6. The display device of claim 1 , wherein a plurality of sub-pixels are divided into first sub-pixels of a first color and second sub-pixels of a different second color,
wherein the power source voltages comprise a first power source voltage supplied to anodes of organic light emitting diodes of the first sub-pixels and a second power source voltage supplied to anodes of organic light emitting diodes of the second sub-pixels, and
wherein the power supply controls the first power source voltage and the second power source voltage in accordance with the control value signals.

7. The display device of claim 6 , wherein the control value signals comprise a first feedback control value signal corresponding to the first color and a second feedback control value signal corresponding to the second color,
wherein the analog dimming values comprise a first analog dimming value corresponding to the first color and a second analog dimming value corresponding to the second color, and
wherein the digital dimming values comprise a first digital dimming value corresponding to the first color and a second digital dimming value corresponding to the second color.

8. A self-lighting type of display device in which output luminance is a function of analog drive voltages and corresponding digital grayscale command signals, the display device comprising:
a frame operation processor configured for generating analog dimming value signals corresponding to to-be-output ones of the analog drive voltages and configured for generating corresponding digital dimming value signals corresponding to to-be-output ones of the digital grayscale command signals, the frame operation processor being responsive to supplied current limiting parameters, the frame operation processor configured for generating control value signals using the generated analog dimming value signals and the digital dimming value signals;
an image data processor configured for changing initial grayscale digital data values of input video signals of one frame by using digital dimming values generated by the frame operation processor;
a self-lighting type of display panel including a plurality of self-lighting sub-pixels configured to display an image corresponding to the input video signals of a respective image frame; and
a variable power supply configured for controlling power source voltages used to drive the sub-pixels of the display panel, the power source voltages being controlled in accordance with the control value signals generated by the frame operation processor, wherein the supplied current limiting parameters comprise a screen color temperature, a power consumption limiting value, and a user selected dimming value, and wherein the frame operation processor comprises:
a current value operator for calculating actual current values in the frame using the screen color temperature;
a dimming value operator for generating the analog dimming values and the digital dimming values using the actual current values, the power consumption limiting value, and the user dimming value and calculating target current values in the frame using the analog dimming values and the digital dimming values; and
a voltage controller for comparing measured current values of the sub-pixels with the target current values to thereby generate the control value signals.

9. The display device of claim 8 , wherein the power supply includes measurement circuitry configured to measure current values drawn by the sub-pixels in response to the power source voltages supplied to the sub-pixels.

10. The display device of claim 8 , wherein the voltage controller generates its control value signals such that they increase the power source voltages when the measured current values are less than the target current values.

11. The display device of claim 8 , wherein the dimming value operator comprises:
a net power control (NPC) logic processor for determining a scale variable of a corresponding frame by a load factor calculated by the actual current values drawn in the frame;
a divider for dividing the scale variable into analog scale variables and digital scale variables; and
a dimming value determiner for generating the analog dimming values using the analog scale variables and using the user selected dimming value and generating the digital dimming values using the digital scale values and the user dimming value.

12. The display device of claim 8 , wherein the dimming value operator comprises a target current value operator for calculating the target current values by multiplications of the analog dimming values, the digital dimming values, and the actual current values.

13. A method of driving a display device including a plurality of self-lighting sub-pixels, where output luminances of the sub-pixels are functions of analog drive voltages supplied to the sub-pixels and also of corresponding digital grayscale command signals used to control the sub-pixels, the method comprising:
generating analog di

Assignees

• Samsung Display Co Ltd

Inventors

• Lee Baek-Woon
• Kim Do-Ik

Classifications

• G09G5/10

  Intensity circuits · CPC title

• G09G2320/0271

  Adjustment of the gradation levels within the range of the gradation scale, e.g. by redistribution or clipping · CPC title

• G09G2320/0666

  for control of colour parameters, e.g. colour temperature · CPC title

• G09G2330/028

  Generation of voltages supplied to electrode drivers in a matrix display other than LCD · CPC title

• G09G3/3258 Primary

  with pixel circuitry controlling the voltage across the light-emitting element · CPC title