Energy saving passive matrix display device and method for driving the column voltage having reduced transitions
First Claim
1. Display device comprising:
- a liquid crystal material between a first substrate provided with row electrodes and a second substrate provided with column electrodes, in which overlapping parts of the row and column electrodes define pixels;
driving means for driving the column electrodes in conformity with an image to be displayed, wherein column voltages Gj(t) are supplyable to the column electrodes, wherein the column voltages Gj(t) to be supplied are selectable from a predetermined number of column voltages levels; and
driving means for driving the row electrodes, wherein the row electrodes supply groups of p rows (p>
=1) with mutually orthogonal selection signals for driving pixels and the groups of p rows are driven for the duration of a row selection time p×
nfrc during a superframe including nfrc frames for generating grey scales,wherein the row selection time is subdivided in npwm sub selection time slots and the grey scales are coded in grey scale tables having nfrc phases with npwm sub selection time slots,wherein for the nfrc frames of the superframe the grey scales are generated by using phase mixing, defining which phase of grey scale coding is used for a certain frame,wherein a column voltage Gj(t) is calculated depending on the grey scales to be displayed by the p concurrently driven pixels in a column and depending on the used mutually orthogonal selection signals Fi for the corresponding group of rows,wherein a change in the column voltage level is defining a transition, andwherein the column voltage GM) to be supplied to a column electrode has always less transitions per row selection time than the number npwm of sub selection time slots of the row selection time.
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Abstract
Method of driving a liquid crystal display by supplying selectable column voltages Gj(t) from a predetermined number of column voltages levels, selection signals to groups of mutually orthogonal p rows (p≧1) for the duration of a row selection time p×nfrc during a supcrframe nfrc to generate grey scales. The column voltage is calculated depending on the grey scales of the p pixels in a column and on the mutually orthogonal selection signals Fi for the corresponding group of rows. The row selection time is subdivided in npwm sub selection time. The grey scales are coded in grey scale tables having nfrc phases with npwm. The superframes grey scales are generated using phase mixing. The change in the column voltage level defines a transition. The column voltage has always less transitions per row selection time than the number npwm of sub selection time of the row selection time.
9 Citations
13 Claims
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1. Display device comprising:
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a liquid crystal material between a first substrate provided with row electrodes and a second substrate provided with column electrodes, in which overlapping parts of the row and column electrodes define pixels; driving means for driving the column electrodes in conformity with an image to be displayed, wherein column voltages Gj(t) are supplyable to the column electrodes, wherein the column voltages Gj(t) to be supplied are selectable from a predetermined number of column voltages levels; and driving means for driving the row electrodes, wherein the row electrodes supply groups of p rows (p>
=1) with mutually orthogonal selection signals for driving pixels and the groups of p rows are driven for the duration of a row selection time p×
nfrc during a superframe including nfrc frames for generating grey scales,wherein the row selection time is subdivided in npwm sub selection time slots and the grey scales are coded in grey scale tables having nfrc phases with npwm sub selection time slots, wherein for the nfrc frames of the superframe the grey scales are generated by using phase mixing, defining which phase of grey scale coding is used for a certain frame, wherein a column voltage Gj(t) is calculated depending on the grey scales to be displayed by the p concurrently driven pixels in a column and depending on the used mutually orthogonal selection signals Fi for the corresponding group of rows, wherein a change in the column voltage level is defining a transition, and wherein the column voltage GM) to be supplied to a column electrode has always less transitions per row selection time than the number npwm of sub selection time slots of the row selection time. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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Specification