Hacker News Reader

Comment by wtallis | Hacker News Reader

Can't any LCD be made into a low-persistence display just by pulsing the backlight? I don't see how OLED is necessarily any better.

View on HN

The persistence is just 1 factor... LCD response time is very slow compared to OLED (~5ms vs ~0.01ms). Every millisecond is important when it comes to VR.

So, the persistence isn't really a factor at all, just the response time.

Well persistence is a factor too. Say your display is updating at 120hz without low persistence... the image stays on screen for 8ms, so you have, say, 1ms of accurate image plus 7ms displaying an inaccurate image. For whatever reason our brains prefer to have no image rather than an inaccurate image, so it helps to turn off the display for that 7/8 of a frame.

While you can do that with LCD, you have to wait 5ms for the pixels to change before you can strobe, so your frame is an extra 5ms out of date. That's my understanding at least, I'm not an expert by any means.

I wouldn't describe that as persistence being a problem, since obviously the LCD can be illuminated for arbitrarily short periods of time. The response time penalty applies regardless of whether you're trying to run the LCD in a low-persistence mode. An OLED's response time advantage over LCDs is across-the-board and completely orthogonal to persistence (where some kinds of backlights could enable LCDs to strobe even faster than OLEDs), and the impact of 5ms extra lag for VR applications will be about the same with or without strobing.

Reply on news.ycombinator.com