Hee Eun Lee is from LG and she spoke about power reduction in mobile display devices by reducing refresh rates
For smartphones, hardware is improving, but the power consumption remains an issue. Refreshing the panel takes 40% of the power used by the display system. Simply reducing refresh rates means a potential problem with flicker. Lee has done some research to try to find where the optimum trade-off is.Power in smartphones but note that the data is from 2002
ISO13406-2 has two ways to calculate flicker – predicted flicker energy and observed. When observed is greater than predicted, the user may see flicker.
The flicker became visible according to ISO at between 35 to 45 Hz, but the ISO test only uses patterns, not real content and doesn’t take account of brightness, so Lee looked at “Just noticeable differences” and “just acceptable differences”.
By dropping to 43.5Hz, 11.2% power reduction was possible, although in a full test, there would also be power saving in the frame buffer (which could not be changed in the experiment). At this frequency, flicker was not a problem.
