Multiplex addressing using auxiliary pulses
AssigneeCentral Research Laboratories Limited
InventorPaul William Herbert Surguy
Life of this patent
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Abstract
In a three-slot addressing scheme for a liquid crystal optical modulator, where the data waveforms comprise a data section, a charge-balancing section and a further section, the form of the further section depends upon the sequence of data waveforms. The further section or pair of adjacent further sections comprises a pair of pulses of opposite polarities which charge-balance each other. The order in which these pulses occur in the pair enhances the effect of the adjacent data section to aid or inhibit switching as appropriate. This facilitates a shorter line address time.
Claims7
A method of addressing a matrix of bistable pixels defined by areas of overlap between members of a first set of electrodes on one side of a layer of ferroelectric material, and members of a second set of electrodes, which cross the members of the first set, on the other side of the layer, in which method blanking signals are applied to the members of the first set of electrodes to effect blanking before unipolar select signals are applied thereto one by one to effect selective switching by simultaneously applying a chosen data waveform to each member of the second set of electrodes, the data waveforms each including a data section coinciding with a select signal, a charge-balancing section, which charge-balances the data section, and one or more further sections, wherein each single further section or pair of further sections, occurring between successive data sections applied to any electrode of the second set, is itself charge-balanced, and comprises at least two non-zero portions, the further section or sections each taking a first form if the data pulses occurring immediately before and after the said further section or sections are different, such that the data pulses switch the pixel into a different state, and a second form if the data pulses occurring immediately before and after the said further section or sections are the same, such that the data pulses cause no switching of the pixel, the further section or sections of the first form having a duration and polarity such as to aid switching, the further section or sections of the second form having a duration and polarity such as to inhibit switching.
An optical modulator apparatus comprising an optical modulator having a matrix of bistable pixels defined by areas of overlap between members of a first set of electrodes on one side of a layer of ferroelectric material, and members of a second set of electrodes, which cross the members of the first set, on the other side of the layer, and an addressing waveform generator having a first set of outputs connected to respective members of the first set of electrodes, and a second set of outputs connected to respective members of the second set of electrodes, the generator being arranged to generate blanking signals followed by select signals at each output of the first set and, simultaneously with each select signal, a chosen data waveform at each output of the second set, the data waveforms each including a data section coinciding with a select signal, a charge-balancing section, which charge-balances the data section, and a further section, wherein the generator is arranged to generate the data waveforms in such manner that each single further section, or pair of further sections occurring between successive data sections at each output of the second set is itself charge-balanced and comprises at least two non-zero portions, and the generator includes means to configure the further section or sections disposed between said successively generated data sections into a first form if successive data portions are different such that the pixel is switched by said data portions, and into a second form if successive data portions are the same such that the pixel is not switched by said data portions, the first form having a duration and polarity such as to aid said switching, and the second form having a duration and polarity such as to inhibit switching.
Dependencies are inferred from the claim text.