DISPLAY DEVICE, PICTURE SIGNAL PROCESSING METHOD, AND PROGRAM

• US 20100127957A1
• Filed: 05/23/2008
• Published: 05/27/2010
• Est. Priority Date: 05/25/2007
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Inoue, Yasuo, Osumi, Toyo, Meguro, Takeya, Kikuchi, Ken
• Granted Patent: US 8,294,642 B2
• Time in Patent Office: Days
• US Class Current: 345/77
• CPC Class Codes: G09G 2300/0819 used for counteracting undesired variations, e.g. feedback or autozeroing
• CPC Class Codes: G09G 2300/0861 with additional control of the display period without amending the charge stored in a pixel memory, e.g. by means of additional select electrodes
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/2011 by amplitude modulation
• CPC Class Codes: G09G 3/2014 by modulation of the duration of a single pulse during which the logic level remains constant
• CPC Class Codes: G09G 3/2081 with combination of amplitude modulation and time modulation space and time error diffusion G09G3/2066
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: H10K 59/12 Active-matrix OLED [AMOLED] displays

Abstract

There is provided a display device including a display unit having pixels, each of which includes a luminescence element that individually becomes luminous depending on a current amount and a pixel circuit for controlling a current applied to the luminescence element according to a voltage signal, where the pixels are arranged in a matrix pattern. The display device includes a luminescence amount regulator for setting a reference duty for regulating a luminescence amount for each one frame, according to the input picture signal, and an adjuster for adjusting an effective duty that regulates, for each one frame, a luminous time for which the luminescence element is luminous, and a gain of the picture signal, based on the reference duty and the input picture signal, so that the luminescence amount is constant before and after adjustment.

Claims

1. A display device including a display unit having pixels, each of which includes a luminescence element that individually becomes luminous depending on a current amount and a pixel circuit for controlling a current applied to the luminescence element according to a voltage signal, scan lines which supply a selection signal for selecting pixels to be luminous to the pixels in a predetermined scanning cycle, and data lines which supply to the pixels the voltage signal according to an input picture signal, the pixels, the scan lines, and the data lines arranged in a matrix pattern, the display device comprising:

a luminescence amount regulator for setting a reference duty for regulating a luminescence amount for each one frame, according to the input picture signal; and

an adjuster for adjusting an effective duty that regulates, for each one frame, a luminous time for which the luminescence element is luminous, and a gain of the picture signal, based on the reference duty and the input picture signal,

wherein the adjuster adjusts the effective duty and the gain of the picture signal so that the luminescence amount for each one frame regulated by the reference duty and the picture signal equals to a luminescence amount for each one frame regulated with the adjusted effective duty and the adjusted gain of the picture signal.

2. The display device according to claim 1, wherein the adjuster adjusts the effective duty to be smaller, as a signal level of the input picture signal is smaller, so that the gain of the picture signal is amplified.

3. The display device according to claim 1, wherein the adjuster includes

a luminous time adjuster for adjusting the effective duty, based on a maximum value of luminance of the picture signal for a predetermined period and the reference duty and

a gain adjuster for adjusting the gain of the picture signal, based on the reference duty set by the luminescence amount regulator and the effective duty adjusted by the luminous time adjuster.

4. The display device according to claim 3,

wherein the luminous time adjuster sets the effective duty to a value equal to or smaller than the reference duty, and

wherein the gain adjuster amplifies the gain of the picture signal, according to a reduction ratio of the effective duty to the reference duty.

5. The display device according to claim 3,

wherein the luminous time adjuster includes

a peak detector for detecting the maximum value of the luminance of the input picture signal for the predetermined period and

a luminous time adjuster for outputting the effective duty obtained by multiplying the reference duty by the maximum value of the luminance detected by the peak detector, and

wherein the gain adjuster includes

a first gain adjuster for multiplying the input picture signal by the reference duty and

a second gain adjuster for dividing the adjusted picture signal output from the first gain adjuster by the effective duty output from the luminous time adjuster.

6. The display device according to claim 1, further comprising:

an average luminance calculator for calculating average luminance for a predetermined period of the input picture signal,

wherein the luminescence amount regulator sets the reference duty depending on the average luminance calculated by the average luminance calculator.

7. The display device according to claim 6, wherein the average luminance calculator includes

a current ratio adjuster for multiplying primary colour signals of the picture signal respectively by adjustment values for the respective primary colour signals based on a voltage-current characteristic and

an average value calculator for calculating average luminance for the predetermined period of the picture signals output from the current ratio adjuster.

8. The display device according to claim 6, wherein the luminescence amount regulator holds a look-up table in which luminance of a picture signal is correlated to the reference duty, and sets the reference duty unique to the average luminance calculated by the average luminance calculator.

9. The display device according to claim 1, further comprising:

a linear converter for adjusting the input picture signal to a linear picture signal by gamma adjustment,

wherein the picture signal input into the adjuster is the picture signal output from the linear converter.

10. The display device according to claim 1, further comprising:

a gamma converter for performing gamma adjustment according to a gamma characteristic of the display unit on the picture signal adjusted by the adjuster.

11. A picture signal processing method for a display device including a display unit having pixels, each of which includes a luminescence element that individually becomes luminous depending on a current amount and a pixel circuit for controlling a current applied to the luminescence element according to a voltage signal, scan lines which supply a selection signal for selecting pixels to be luminous to the pixels in a predetermined scanning cycle, and data lines which supply to the pixels the voltage signal according to an input picture signal, the pixels, the scan lines, and the data lines arranged in a matrix pattern, the picture signal processing method comprising the steps of:

setting a reference duty for regulating a luminescence amount for each one frame, according to the input picture signal; and

adjusting an effective duty that regulates, for each one frame, a luminous time for which the luminescence element is luminous, and a gain of the picture signal, based on the reference duty and the input picture signal,

wherein the step of adjusting adjusts the effective duty and the gain of the picture signal so that the luminescence amount for each one frame regulated with the reference duty and the picture signal equals to a luminescence amount for each one frame regulated with the adjusted effective duty and the adjusted gain of the picture signal.

12. The picture signal processing method according to claim 11, wherein the step of adjusting adjusts the effective duty to be smaller, as a signal level of the input picture signal is smaller, so that the gain of the picture signal is amplified.

13. The picture signal processing method according to claim 11, wherein the step of adjusting includes

a first step of adjusting the effective duty, based on a maximum value of luminance of the picture signal for a predetermined period and the reference duty and

a second step of adjusting the gain of the picture signal, based on the reference duty set in the step of adjusting and the effective duty adjusted in the first step.

14. The picture signal processing method according to claim 13,

wherein the first step sets the effective duty to a value equal to or smaller than the reference duty, and

wherein the second step amplifies the gain of the picture signal, according to a reduction ratio of the effective duty to the reference duty.

15. The picture signal processing method according to claim 13,

wherein the first step includes

a third step of detecting the maximum value of the luminance of the input picture signal for the predetermined period and

a forth step of outputting the effective duty obtained by multiplying the reference duty by the maximum value of the luminance detected in the third step, and

wherein the second step includes

a fifth step of multiplying the input picture signal by the reference duty and

a sixth step of dividing the adjusted picture signal output by the fifth step by the effective duty output by the forth step.

16. The picture signal processing method according to claim 11, further comprising the step of:

calculating average luminance for a predetermined period of the input picture signal,

wherein the step of setting sets the reference duty depending on the average luminance calculated in the step of calculating average luminance.

17. The picture signal processing method according to claim 16, wherein the step of calculating average luminance includes

a seventh step of multiplying primary colour signals of the picture signal respectively by adjustment values for respective primary colour signals based on a voltage-current characteristic and

an eighth step of calculating average luminance for the predetermined period of the picture signals output by the seventh step.

18. The picture signal processing method according to claim 16, wherein a look-up table in which luminance of a picture signal is correlated to the reference duty is held in the step of adjusting, and wherein the step of adjusting sets the reference duty unique to the average luminance calculated in the step of calculating average luminance.

19. The picture signal processing method according to claim 11, further comprising the step of:

adjusting the input picture signal to a linear picture signal by gamma adjustment,

wherein, the picture signal input in the step of adjusting is the picture signal output by the step of adjusting to a linear picture signal.

20. The display device according to claim 11, further comprising the step of:

performing gamma adjustment according to a gamma characteristic of the display unit on the picture signal adjusted in the step of adjusting.

21. A program related to a display device including a display unit having pixels, each of which includes a luminescence element that individually becomes luminous depending on a current amount and a pixel circuit for controlling a current applied to the luminescence element according to a voltage signal, scan lines which supply a selection signal for selecting pixels to be luminous to the pixels in a predetermined scanning cycle, and data lines which supply to the pixels the voltage signal according to an input picture signal, the pixels, the scan lines, and the data lines arranged in a matrix pattern, the program configured to cause a computer to function as:

means for setting a reference duty for regulating a luminescence amount for each one frame, according to the input picture signal; and

means for adjusting an effective duty that regulates, for each one frame, a luminous time for which the luminescence element is luminous, and a gain of the picture signal, based on the reference duty and the input picture signal.