JVC NZ7 Left vs. JVC NX5 Right - PWM comparison.

It seems both JVC NZ7 (laser) and JVC NX5 (bulb) use PWM for brightness control as detected in this iPhone 11 video of the two projectors compared side by side - video taken with 240FPS slow motion on original source.

[@UnLogitech85]

what is PWM?

[@jvonengeln]

Pulse Width Modulation. It’s a way of controlling brightness with on/off duty cycles instead of a more analogue way of applying a percentage of voltage. The flashing is faster than our brain can comprehend, hence why you don’t see it in person but you do see it on slow motion video. The problem is that some peoples eyes can see it. Basically some peoples eyes are constantly adjusting for the varying brightness via muscle dilation. My eyes encounter this issue. So the JVC projectors give me eye fatigue, and a slight feeling of dizziness, even though I can’t SEE the flashing with my brain, my eyes are reacting to the flashing. Brains can only comprehend less than a couple hundred frames per second at top range, but eye dilation can react to thousands of frames per second at top range. It causes discomfort that builds with use. If you websearch PWM + eye strain you’ll find a lot of information on this. It only affects a small minority of people. Less than 1%, but it’s uncomfortable for people who’s eyes are affected. I’ve found I cannot use a JVC projector comfortably because if the PWM. Not all projectors use PWM. Epson LS12000 doesn’t for comparison.

[@jvonengeln]

More discussion and investigation here: www.avsforum.com/threads/laser-based-projectors-and-eye-fatigue-questions-and-discussion.3237865/