Display backlight modulation

• US 9,538,624 B2
• Filed: 12/29/2011
• Issued: 01/03/2017
• Est. Priority Date: 12/29/2011
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Zhang, Yanli, Takagi, Akihiro, Bhowmik, Achintya K., Nanduri, Anil V.
• Primary Examiner(s): Neils, Peggy
• Assistant Examiner(s): Tumebo, Tsion
• Application Number:
  US13/997,599
• Publication Number:
  US 20140062329A1
• Time in Patent Office: 1,832 Days
• Field of Search: 315/209, 315/210
• US Class Current: 1/1
• CPC Class Codes: G09G 2310/08 Details of timing specific for flat panels, other than clock recovery
• CPC Class Codes: G09G 3/342 using several illumination sources separately controlled corresponding to different display panel areas, e.g. along one dimension such as lines
• CPC Class Codes: H05B 47/16 by timing means

Abstract

An apparatus may include a backlight for illuminating a liquid crystal display and a control module for controlling the illumination of the backlight. The control module may alternate between turning the backlight on and off at a first frequency and turning the backlight on and off at a second frequency.

Claims

1. An apparatus to degrade a portion of recorded images of copyrighted material, the apparatus comprising:

a control module to degrade only a portion of recorded images at a time by selectively controlling the illumination of a first backlight to illuminate a first portion of a liquid crystal display and a second backlight to illuminate a second portion of the liquid crystal display, wherein in an enabled state, the control module is configured to turn the first backlight on and off at a first frequency during a first period while the second backlight is not being turned on and off at a second frequency and turn the second backlight on and off at a second frequency during a second period while the first backlight is not being turned on and off at the first frequency where the first frequency is a non-harmonic frequency associated with known recording frequencies of recording devices and the second frequency is a non-harmonic frequency associated with known recording frequencies of recording devices, the second frequency being different than the first frequency, wherein the control module is in the enabled state in response to receiving an indication that recorded image degradation is desired.

2. The apparatus of claim 1, wherein the first non-harmonic frequency and second non-harmonic frequency are in a frequency ranges between 100-115 hertz, 125-139 hertz, 198-205 hertz, 221-235 hertz and 245-259 hertz.

3. The apparatus of claim 1, wherein the control module is to use a first pulse width modulated signal at the first frequency to turn the backlight on and off at the first frequency and a second pulse width modulated signal at the second frequency to turn the backlight on and off at the second frequency.

4. The apparatus of claim 3, wherein the duty cycle of the first pulse width modulated signal is equal to the duty cycle of the second pulse width modulated signal.

5. The apparatus of claim 1, wherein the control module is to turn the backlight on and off at a first frequency for intervals that are greater than one minute and turn the backlight on and off at a second frequency for intervals greater than one minute.

6. An apparatus, comprising:

a first backlight configured to illuminate a first portion of a liquid crystal display;

a second backlight configured to illuminate a second portion of the liquid crystal display; and

a control module to degrade only a portion of recorded images at a time by selectively controlling the illumination of the first and second backlights, wherein in an enabled state, the control module is configured to turn the first backlight on and off at a first frequency during a first period while the second backlight is not being turned on and off at a second frequency and turn the second backlight on and off at a second frequency during a second period while the first backlight is not being turned on and off at the first frequency, where the first frequency is a non-harmonic frequency associated with known recording frequencies of recording devices and the second frequency is a non-harmonic frequency associated with known recording frequencies of recording devices, the second frequency being different than the first frequency, wherein the control module is in the enabled state in response to receiving an indication that recorded image degradation is desired.

7. The apparatus of claim 6, wherein the control module is in the enabled state after receiving an indication that private content, copyrighted content, or any content for which recorded image degradation is to be displayed.

8. The apparatus of claim 6, wherein the control module is to produce a first pulse width modulated signal at the first frequency to turn the first backlight on and off at the first frequency and a second pulse width modulated signal at the second frequency to turn the second backlight on and off at the second frequency.

9. The apparatus of claim 8, wherein the duty cycle of the first pulse width modulated signal is equal to the duty cycle of the second pulse width modulated signal.

10. The apparatus of claim 6, wherein the control module is to change the first frequency to a third frequency.

11. The apparatus of claim 10, wherein the third frequency is to be random chosen.

12. The apparatus of claim 10, wherein the control module is to randomly change the first frequency to the third frequency.

13. The apparatus of claim 6, further comprising a third backlight configured to illuminate a third portion of the liquid crystal display.

14. The apparatus of claim 13, wherein the control module is to control the illumination of the third backlight and is further configured to turn the third backlight on and off at a third frequency.

15. An electronic device that comprises the apparatus of claim 6.

16. A method, comprising:

in response to receiving an indication that recorded image degradation is desired, turning a first backlight on and off at a first frequency associated with known recording frequencies of recording devices, the first backlight illuminating a first portion of a liquid crystal display so that only a portion of recorded images are degraded at a time; and

turning a second backlight on and off at a second frequency associated with known recording frequencies of recording devices, the second backlight illuminating a second portion of the liquid crystal display, the second frequency being different than the first frequency where the first backlight is turned on and off at the first frequency during a first period while the second backlight is not being turned on and off at the second frequency and the second backlight is turned on and off at the second frequency during the second period while the first backlight is not being turned on and off at the first frequency.

17. The method of claim 16, further comprising changing the first frequency at which the first backlight is turned on and off.

18. The method of claim 17, wherein the first frequency is changed at a random interval and to a random frequency.

19. The method of claim 17, further comprising changing the second frequency at which the second backlight is turned on and off.

20. The method of claim 19, wherein the second frequency is changed at a random interval and to a random frequency.

21. The method of claim 16, wherein the first backlight is turned on and off at the first frequency during a first period and the second backlight is not turned on and off at the second frequency during the first period and wherein the first backlight is not turned on and off at the first frequency during a second period and the second backlight is turned on and off at the second frequency during the second period.

22. An apparatus, comprising:

a battery;

a first backlight configured to use power from the battery to illuminate a first portion of the liquid crystal display;

a second backlight configured to use power from the battery to illuminate a second portion of the liquid crystal display; and

a control module to selectively control the illumination of the first and second backlights, wherein in an enabled state, the control module is configured to turn the first backlight on and off at a first frequency during a first period while the second backlight is not being turned on and off at a second frequency and turn the second backlight on and off at a second frequency during a second period while the first backlight is not being turned on and off at the first frequency, where the first frequency is a non-harmonic frequency associated with known recording frequencies of recording devices and the second frequency is a non-harmonic frequency associated with known recording frequencies of recording devices, the second frequency being different than the first frequency, wherein the control module is in the enabled state in response to receiving an indication that recorded image degradation is desired.

23. The system of claim 22, wherein the control module is in the enabled state after receiving an indication that private content or copyrighted content is to be displayed.

24. The system of claim 22, wherein the control module is to use a first pulse width modulated signal at the first frequency to turn the backlight on and off at the first frequency and a second pulse width modulated signal at the second frequency to turn the backlight on and off at the second frequency.

25. The system of claim 24, wherein the duty cycle of the first pulse width modulated signal is equal to the duty cycle of the second pulse width modulated signal.

26. The system of claim 22, wherein the control module is to turn the backlight on and off at a first frequency for intervals that are greater than one minute and turn the backlight on and off at a second frequency for intervals greater than one minute.