Push-Pull Liquid Crystal Modulator For Electronic Stereoscopic Display

Abstract

A new type of large liquid crystal modulator, the ZScreen(R), has been developed for use in a stereoscopic display system and has been put into production by StereoGraphics Corporation.The fabrication of large area surface mode liquid crystal cells requiring extreme uniformity of thickness has been achieved in a two year development program.Two of these cells are placed in optical series, with their alignment axes orthogonal. Laminated to the liquid crystal cells is a linear polarizer whose absorption axis besects the alignment axes of the liquid crystal cells. When placed in intimate juxtaposition with a CRT display with the linear polarizer facing the CRT screen, and when the cells are driven electrically out of phase, the light output of the CRT is alternately left and right handed circularly polarized.When this so-called push -pull modulator is viewed through passive circularly pollarized spectacles worn by an observer, a shutter is formed having a high dynamic range. Each eye of the observer is sequentially occluded.By properly choosing the parameters of construction, such a liquid crystal modulator can have a broad cone of view, high dynamic range, and good transmission. This type of modulator is superior to a single liquid crystal cell modulator since it has fast and symmetrical rise and decay times and identical dynamic range for both eyes.These features are of particular importance in a field -sequential stereoscopic system, because the rise and decay time of such a shutter should take place substantially within the vertical blanking interval, which is generally on the order of a millisecond.The 9 -inch diagonal versions of the modulator have been in production since the last quarter of 1986 and now are being supplied in up to 19 -inch diagonal sizes for computer graphics and video displays.

<title>High-contrast and fast nematic liquid crystal shutter for projection displays</title>

“…Some examples of these devices are 3-D displays with switchable glasses [1] for multimedia systems and color field-sequential devices [2]. Liquid crystal (LC) layers are very convenient for these purposes.…”

“…The authors believe the investigated shutter version meets the requirements to projection 3-D displays with switchable glasses [1] for multimedia systems and color field-sequential devices [2].…”