Discussion in 'Article Discussion' started by bit-tech, 27 May 2019.
The hard part is not syncing the backlight with varying update intervals (that's as trivial as syncing it with consistent update intervals) or even dealing with low frame-rate situations: panel update hits a refresh floor at which point either the card (DP Adaptive Sync) or the panel controller (G-Sync) generate duplicate frames. Set the floor to 60Hz (if you never want to pulse less frequently than that) and framedouble below that, and pulse the backlight at that frequency. As long as you have a panel capable of at least x-2x refresh rates (where x is your chosen baseline, so e.g. 60Hz would need 60-120Hz).
No, the hard part is that if you vary the interval between backlight pulses, you vary the perceptual brightness of the panel. That means that individual backlight pulses need to be different intensities, and they need to change intensity within the interframe interval. AND because you do not know when the next frame will arrive you have to integrate up until the next frame arrives, then determine the backlight brightness and charge the backlight driver in the time interval between the frame starting to arrive from the input, and the frame completing readout from the driver (single-digit milliseconds to microseconds).
A good chunk of the cost of G-Sync HDR monitors is in the FALD backlight driver boards, to allow each of the backlight zones to be driven at a different level each frame. Asus may be repurposing one of the driver modules to drive a single edge-lit backight, at less of a cost increase than using the multiple modules needed for FALD.
One of the best things monitor manufacturers have done in recent years, is move away from PWM backlight control, thus making LCD monitors flicker free. My current monitor is flicker free and is the first LCD monitor I have had that doesn't cause me to get a headache.
Backlight strobing seems such a massive step backwards...
Not necessarily. Moving from PWM backlighting to constant-intensity backlighting turns quantised motion blur into smooth motion blur, but it doesn't do anything to reduce the motion blur of a sample-and-hold display. Pulsed backlighting elimiantes motion blur at the expense of peak brightness.
No more so than with CRTs (which have a monumentally shorter persistence time).
Separate names with a comma.