US 12,437,727 B2
Variable refresh rate control using PWM-aligned frame periods
Sang Young Youn, Cupertino, CA (US); Sun-il Chang, San Jose, CA (US); Wonjae Choi, San Jose, CA (US); and Sangmoo Choi, Palo Alto, CA (US)
Assigned to GOOGLE LLC, Mountain View, CA (US)
Filed by GOOGLE LLC, Mountain View, CA (US)
Filed on Mar. 29, 2024, as Appl. No. 18/621,591.
Application 18/621,591 is a continuation of application No. 17/786,961, granted, now 11,948,520, previously published as PCT/US2020/025980, filed on Mar. 31, 2020.
Prior Publication US 2024/0265884 A1, Aug. 8, 2024
Int. Cl. G09G 3/34 (2006.01)
CPC G09G 3/3406 (2013.01) [G09G 2320/0252 (2013.01); G09G 2320/064 (2013.01); G09G 2340/0435 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A system comprising:
a display control subsystem coupleable to a display panel, the display control subsystem configured to:
receive a sequence of frames having a variable rate;
control a brightness of frames displayed at a display panel via pulse width modulation (PWM) of a brightness control signal provided to the display panel;
provide frames for display at the display panel with a variable refresh rate such that a start of each frame period is aligned with a corresponding PWM cycle of the brightness control signal and such that each frame period spans an integer multiple of PWM cycles of the brightness control signal; and
in response to a delay in rendering of a frame based on a target frame rate, implement a compensatory variable refresh rate (VRR) scheme that maintains an effective PWM duty cycle of the brightness control signal for each display frame period of one or more display frame periods.