Liquid crystal display and driver
AssigneeKoninklijke Philips Electronics N.V.
InventorsJason R. Hector, Alan G. Knapp
Life of this patent
Estimating the term…
Abstract
A liquid crystal display has a plurality of buffers 46 controlling a plurality of column lines. The buffers have a bias current control input 47 which is controlled, in the example by timing circuitry 50, to current during the row period for writing to each row of pixels. In particular, the row period may be divided between a drive period with a high buffer bias current and a voltage maintenance period with a lower buffer bias current.
Claims12
A liquid crystal display comprising:
- a plurality of liquid crystal pixel electrodes arranged as an array of rows and columns;
- a plurality of row and column lines for driving the liquid crystal pixel electrodes;
- a plurality of buffers for driving the plurality of column lines, the buffers being operable at a variety of bias currents;
- and
- means for varying the buffer bias currents during a plurality of row periods, the row periods being periods for writing to a row of pixel electrodes, whilst maintaining the voltage output to provide different bias currents at different times within individual row periods.
A liquid crystal display according to any preceding claim wherein the buffers each have a bias current control input for controlling the bias current.
A liquid crystal display according to any preceding claim wherein each buffer has a signal input and output, the output being connected to drive a respective column line and the signal input being connected to a digital to analogue conversion means.
A method of operating a liquid crystal display having a plurality of rows and columns of pixel electrodes driven by row and column lines, the method comprising:
- converting a sequence of digital signals representing a series of image frames into a sequence of voltage levels for driving the column lines;
- driving the plurality of column lines from a plurality of buffers operable at a variety of bias currents during a plurality of row periods, the row periods being periods for charging each successive row of pixel electrodes;
- and
- varying the buffer bias currents during each row period to provide different bias currents at different times within individual row periods.
A liquid crystal display driver comprising:
- a digital input for accepting a sequence of digital signals representing a series of image frames;
- digital to analogue conversion means for converting the sequence of digital signals on the digital input and outputting corresponding voltage levels;
- a plurality of buffers for driving a plurality of column lines of the liquid crystal display during a plurality of row periods for writing to each row of pixel electrodes, the buffers being operable at a variety of bias currents;
- and
- means for varying the buffer bias currents whilst maintaining the voltage output to provide different bias currents at different times within individual row periods.
Dependencies are inferred from the claim text.