A method for EMI evaluation of notebook computer liquid crystal display panels while eliminating the contribution of computer generated EMI

Abstract

The radiated emissions from a liquid crystal display (LCD) panel can be the most difficult signals to attenuate in a notebook computer system. This paper describes a method for evaluating notebook computer LCD panels using a reference test setup. The center of this test setup is a circuit that produces the data, clock, and sync signals required to operate the panel in an EMI producing mode. This circuit (comprising of an oscillator, a programmable array logic part, and a line driver) eliminates the need for a notebook computer during testing, allowing for evaluation of only the LCD panel. By evaluating the panel as an individual component, early problem identification can be realized. From this realization, resolution of the EMI problem can be obtained independent of the system in which the LCD panel is installed.