A Low-Power Time-Synchronization Processor With Symmetric Even/Odd Timer for Charge-Shared LCD Driving of 3DTV Active Shutter Glasses

Abstract

The proposed sync-processor enables a fractional-order time-synchronization to generate an efficient lens shutter-control timing for the charge-shared LCD lens driving in the 3DTV active shutter glasses. This design implements a universal sync-edge tracer as a pre-processor to form the unit event of the wireless sync-packet, a fractional-order timer to measure the timing period for accurate synchronization of the stereo-vision, and charge-shared driver controlled by the proposed symmetric even/odd timer to provide an efficient charge equalization method. The proposed symmetric even/odd timer block sequentially generates the driver switching events by distributing the driver activation into four pins of the LCD active shutter lenses to reuse the pre-pumped charge of the charge-shared LCD driver, which is sequentially shared between four pins for LCD lens. The proposed sequential lens control by distributing the charge-sharing events also enables the reduction of the hardware size required for the counters and overflow comparators in the switching timer to generate the pulse width modulation (PWM) pulse waveform of the LCD lens control for time-sequential 3D stereo-vision. The implemented one-chip solution, which is applied with all of the proposed techniques to improve the previous work, reduces about 140 mu A of LCD lens driving current, which results in about 30% current reduction in total. This paper describes the system's architecture and the details of the proposed techniques, while also identifying the key concepts and functions.