Control of light-emitting-diode backlight illumination through frame insertion
View Patent ↗System(s) and method(s) are provided to regulate backlighting in a light emitting diode (LED)-based display through a sequence of alternate pulse-width-modulation (PWM) frame or sub-frame insertions. Alternate PWM frames or sub-frames can be black or non-black. A plurality of pixels in the display is partitioned into at least one zone including one or more rows of pixels; the at least one zone determines sub-frame period based on refresh frequency of the display. A sequence of alternate PWM sub-frames includes at least one alternate sub-frame and at least one normal sub-frame. Alternate PWM frames or alternate PWM sub-frames include a phase delay during which a backlight unit is turned off, and a PWM sequence in which the backlight unit is turned on with a finite duty cycle for the remainder of the PWM frame or sub-frame. A sequence of alternate PWM sub-frames can be configured internally or externally. Internal configuration can be synchronous with a reference signal whereas external configuration relies on external reference signal.
1. A display, comprising:
a plurality of pixels partitioned in a set of groups of one or more pixel rows;
backlight circuitry comprising a backlight unit that includes a set of light emitting diode (LEDs) strings; and
a display controller that configures a sequence of one or more sub-frames or a sequence of one or more frames to update the plurality of pixels, wherein for the sequence of one or more sub-frames, at least one sub-frame in the sequence includes a first phase delay in which the backlight unit is turned off and a first pulse-width modulation (PWM) sequence that regulates operation of the backlight unit; and the phase delay is longer than respective phase delays of the one or more sub-frames in the sequence excluding the at least one sub-frame.
2. The display of claim 1 , wherein, for the sequence of one or more frames, at least one frame in the sequence includes a second phase delay in which the backlight unit is turned off and a second pulse-width modulation (PWM) sequence that regulates operation of the backlight unit; and the phase delay is longer than respective phase delays of the one or more frames in the sequence excluding the at least one frame.
3. The display of claim 2 , wherein the display controller includes a timing signal generator that produces a timing signal that defines a first period of one or more sub-frames in the sequence of one or more sub-frames or a second period of one or more frames in the sequence of one or more frames, wherein the first period or the second period is a fraction of a disparate period of a reference timing signal.
4. The display of claim 3 , wherein the reference timing signal is a vertical synchronization (VSYNC) clock signal of the display.
5. The display of claim 2 , wherein the display controller includes a phase signal generator that configures at least one of the phase delay and a duty cycle for at least one of the first PWM sequence and the second PWM sequence.
6. The display of claim 5 , wherein, the display controller includes an alternate signal selector that conveys an indication to the timing signal generator to insert the at least one sub-frame in the sequence of one or more sub-frames with the disparate period, wherein the indication supplies a selection of an internal control signal that defines the sequence of one or more sub-frames.
7. The display of claim 5 , wherein, the alternate signal selector receives an external timing signal that defines at least in part at least one of the sequence of one or more sub-frames or the sequence of one or more frames.
8. The display of claim 7 , wherein the display controller includes a phase signal generator that configures the respective phase delays of the one or more sub-frames in the sequence excluding the at least one sub-frame.
9. The display of claim 8 , wherein the phase signal generator configures the respective phase delays of the one or more frames in the sequence excluding the at least one frame.
10. The display of claim 8 , wherein the phase signal generator configures a duty cycle value for a third PWM sequence for the one or more sub-frames in the sequence excluding the at least one sub-frame.
11. The display of claim 10 , wherein the phase signal generator configures a duty cycle value for a fourth PWM sequence for the one or more frames in the sequence excluding the at least one frame.
12. The display of claim 1 , wherein the display controller includes a memory that retains a set of registers comprising at least one of a set of phase delay values and a set of duty cycle values.
13. A method, comprising:
configuring a control timing signal by multiplying a clock signal with a multiplier component;
selecting one of an alternate pulse-width modulation (PWM) frame control signal or an alternate PWM sub-frame control signal based on the control timing signal;
based on the selection, configuring a sequence of alternate PWM sub-frame insertions based on the phase signal;
based on the configuration, determining one of a first set of phase delay values and a first set of duty cycle values that regulate backlighting in a display for an alternate PWM sub-frame insertion in the sequence, or a second set of phase delay values and a second set of duty cycle values that regulate backlighting in a display for an alternate PWM frame insertion in the sequence; and
regulating backlighting in the display based at least in part on at least one of (i) the sequence of alternate PWM sub-frame insertions and the first set of phase delay values and the first set of duty cycle values, or (ii) the sequence of alternate PWM frame insertions and the set of phase delay values and the set of duty cycle values.
14. The method of claim 13 , wherein selecting the alternate PWM frame control signal includes selecting a first internal control signal or a first external control signal.
15. The method of claim 14 , wherein selecting the first internal signal includes configuring the control timing signal as the alternate PWM frame control signal.
16. The method of claim 14 , wherein selecting the first external signal includes:
receiving an external signal; and
configuring the external signal as the alternate PWM frame signal.
17. The method of claim 14 , wherein selecting the second external signal includes:
receiving an external signal; and
configuring the external signal as the alternate PWM sub-frame signal.
18. The method of claim 13 , wherein selecting the alternate PWM sub-frame control signal includes selecting a second internal control signal or a second external control signal.
19. The method of claim 18 , wherein selecting the second internal signal includes configuring the control timing signal as the alternate PWM sub-frame control signal.
20. The method of claim 13 , wherein the configuring includes effecting an alternate PWM sub-frame insertion with a period of the clock signal.
21. The method of claim 13 , wherein the determining includes extracting at least one phase delay value and at least one of duty cycle value.
22. A liquid crystal display, comprising:
means for configuring a control timing signal by multiplying a clock signal with a multiplier component;
means for establishing a phase signal;
means for configuring one of a sequence of alternate pulse-width modulation (PWM) sub-frame insertions or a sequence of alternate PWM frame insertions based on the phase signal;
means for determining a first set of phase delays and a first set of duty cycles that regulate backlighting in the liquid crystal display for one of an alternate PWM sub-frame insertion in the sequence or an alternate PWM frame insertion in the sequence; and
means for regulating backlighting in the liquid crystal display based at least in part on (i) one of the sequence of alternate PWM sub-frame insertions or the sequence of alternate PWM frame insertions and (ii) the first set of phase delays and the first set of duty cycles.
23. The liquid crystal display of claim 22 , wherein the mans for establishing the phase signal includes one of (a) means for receiving an external signal and means for configuring the external signal as the phase signal; or (b) means for configuring the control timing signal as the phase signal.