LCD ADDRESSING SYSTEM

• Main Authors: CLIFTON, BENJAMIN ROBERT, SCHEFFER, TERRY JAMES
• Format: Patent
• Language: English; French
• Published: 13.04.1999
• Edition: 6
• Subjects: ADVERTISING; ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICESUSING STATIC MEANS TO PRESENT VARIABLE INFORMATION; CRYPTOGRAPHY; DEVICES OR ARRANGEMENTS, THE OPTICAL OPERATION OF WHICH ISMODIFIED BY CHANGING THE OPTICAL PROPERTIES OF THE MEDIUM OF THEDEVICES OR ARRANGEMENTS FOR THE CONTROL OF THE INTENSITY,COLOUR, PHASE, POLARISATION OR DIRECTION OF LIGHT, e.g.SWITCHING, GATING, MODULATING OR DEMODULATING; DISPLAY; EDUCATION; FREQUENCY-CHANGING; NON-LINEAR OPTICS; OPTICAL ANALOGUE/DIGITAL CONVERTERS; OPTICAL LOGIC ELEMENTS; OPTICS; PHYSICS; SEALS; TECHNIQUES OR PROCEDURES FOR THE OPERATION THEREOF

A method and apparatus for addressing faster responding liquid crystal panels (LCDs) so that video rate, high information content LCDs having time constants on the order of 50ms or less, are perceived as having brighter bright states and darker dark states by limiting peak voltage levels across the pixels. A first set of LCD electrodes are continuously driven with signals each comprising a train of pulses that: are periodic in time; have a common period T; are independent of the information to be displayed; and are preferably orthonormal. A plurality of column signals are generated from the collective information state of the pixels defined by the overlap with a second electrode pattern. Each column signal is proportional to the sum obtained by considering each pixel in the column and adding the voltage of that pixel's row at time t to the sum if the pixel is to be "off" and subtracting the voltage of that pixel's row at time t from the sum if the pixel is to be "on". If the row signals only switch between two voltage levels, the sum may be represented as the sum of the exclusive or (XOR) products of the logic level of the amplitude of each row signal times the logic level of the information state of the pixel corresponding to that row. Hardware implementation comprises an external video source, a controller that receives and formats video data and timing information, a storage means for storing display data, a row signal generator, a column signal generator, and at least one LCD panel. Alternative embodiments provide gray scale shading and circuits to reduce the magnitude of the column signals, as well as the number of column voltage levels required to generate a displayed image.