Patent ID: 6804138
Filing Date: 2004-10-12
Classification: G09G,G11C

Abstract:
A method of driving a passive matrix addressed display or memory array of cells comprising an electrically polarizable ferroelectric material exhibiting hysteresis, wherein the polarization state of individual, separately addressable cells can be switched to a desired condition by application of electric potentials or voltages to corresponding word and bit lines in said passive matrix, the method comprising the steps of:controlling individually a potential on selected word and bit lines to approach or coincide with one of n predefined potential levels, the potentials on said selected word and bit lines forming subsets of said n predefined potentials involving nWORD and nBIT potentials, respectively; controlling the potentials on all word- and bit lines in a time-coordinated fashion according to a protocol or timing sequence, whereby word lines are latched in a predetermined sequence to potentials selected among the nWORD potentials, while bit lines are either latched in a predetermined sequence to potentials selected among the nBIT potentials or are connected during a certain period of the timing sequence to sensing circuitry that senses charges flowing between at least one cell and its associated the bit line, to form a crossline voltage potential between bit lines and word lines; and arranging said timing sequence to encompass at least two distinct parts, including a read cycle during which charges flowing between a said selected bit line and the cells connecting to said bit line as sensed by the sensing circuitry, and a refresh/write cycle during which polarization state(s) in cells connecting with selected word- and bit lines are controlled to correspond with a set of predetermined values, where during read/write cycles each unselected cell is &frac13; Vs or greater, where Vs is the voltage across an addressed cell during read, refresh, and write cycles, wherein all memory locations are accessed solely by its corresponding bit and word line on a single array layer.