Exit Pupil Modulation allows an LCD-based VR headset using a pancake lens to achieve the visual performance of an OLED display with up to a 90% power reduction. The demo at DisplayWeek 2024 showed this result in a modified MetaQuest 3 pancake optic.
Exit Pupil Modulation creates two imaging systems. The first is a modified LED array that is imaged in the exit pupil of the pancake lens. The second creates a virtual image of the LCD panel, just as in the unmodified MetaQuest3. The modified backlight unit has a microlens array designed so that each LED in the array fills the entire LCD panel. While this may look like local dimming, it is not. In an LCD display with local dimming, each LED modifies the luminance in a small part of the LCD panel - a zone. With Exit Pupil Modulation, each LED floods the LCD panel so modifications to the LEDs in the backlight alter the size of the eyebox or exit pupil. This allows the designer to trade off power & contrast vs. eyebox size. This can be a very useful tradeoff, especially if eye tracking is employed to mitigate the smaller eyebox concern.
1 окт 2024
