A high-efficiency low-power chip-based CMOS liquid crystal driver for tunable electro-optic eyewear

Abstract

A high-efficiency low-power chip-based liquid crystal (LC) driver has been successfully designed and implemented for adaptive electro-optic eyewear including tunable vision correction devices (eyeglass, contact lens, intraocular lens, occluder, and prism), phoropter, iris, head-mounted display, and 3D imaging. The driver can generate a 1 kHz bipolar square wave with magnitude tunable from 0 V to 15 V to change the lens focus adaptively. The LC driver output magnitude is controlled by a reference DC voltage that is manually tunable between 0 and 3 V. A multi-mode 1×/2×/3×/4×/5× charge pump is developed for DC-DC conversion to expand the output range with a fast-sink function implemented to regulate the charge pump output. In addition, a new four-phase H-bridge driving scheme is employed to improve the DC/AC inverter efficiency. The LC driver has been successfully implemented and tested as an IC chip (8.6 mm × 8.6 mm) using AMS 0.18 µm High-Voltage CMOS technology.