Method of driving a ferroelectric to display device to achieve gray scales

Claim 3

A method as claimed in claim 1, characterized in that the period during which the data signals are presented to the column electrodes covers at most half the switching period of the ferro-electric liquid crystal.

Claim 4

A method as claimed in claim 1 for displaying a grey scale, characterized in that the grey scale is determined by the duration and amplitude of a data signal presented.

Claim 5

A method as claimed in claim 1, characterized in that the row of picture elements is selected for data display during at most half a line selection period and in that the voltage of the data signal determines the grey scale.

Claim 6

A method as claimed in claim 1, characterized in that picture elements in the extreme transmission state are substantially non-transmissive.

Claim 7

A method as claimed in claim 1, characterized in that the line selection period is at most 64 μsec.

Claim 8

A method as claimed in claim 2, characterized in that picture elements in the extreme transmission state are substantially non-transmissive.

Claim 9

A method as claimed in claim 3, characterized in that picture elements in the extreme transmission state are substantially non-transmissive.

Claim 10

A method as claimed in claim 4, characterized in that picture elements in the extreme transmission state are substantially non-transmissive.

Claim 11

A method as claimed in claim 2, characterized in that the line selection period is at most 64 μsec.

Claim 12

A method as claimed in claim 3, characterized in that the line selection period is at most 64 μsec.

Claim 13

A method as claimed in claim 4, characterized in that the line selection period is at most 64 μsec.

Claim 14

A method as claimed in claim 5, characterized in that the line selection period is at most 64 μsec.

Claim 15

A display device comprising: a ferro-electro-optical display medium between two supporting plates; a system of picture elements arranged in rows and columns, each picture element being constituted by picture electrodes arranged on the facing surfaces of the supporting plates, and a system of row electrodes and column electrodes for driving the picture elements, the column electrodes connected to outputs of multiplex circuits which switch the column electrodes between the data signals to be displayed and an auxiliary signal so as to bring the liquid crystal element to an extreme state prior to application of the data signal; a control and synchronization circuit, which circuit, simultaneously with a selection voltage on a row of picture elements to be displayed, first causes an auxiliary signal to appear on the column electrodes via the multiplex circuits, which signal has a sufficient duration and amplitude to bring a picture element to an extreme state, and which circuit subsequently causes data signals to appear on the column electrodes, characterized in that the auxiliary signal is presented to the picture elements via active switching elements during at least a first part of a line selection period and in that the picture elements are connected to the column electrodes via the same switching elements during a second part of the line selection period in order to present data signals to the picture elements, and further characterized in that the period during which the data signals are presented to the column electrodes is short with represent to the switching period of the ferro-electric liquid crystal.

Claim 16

A display device comprising: a ferro-electro-optical display medium between two supporting plates; a system of picture elements arranged in rows and columns, each picture element being constituted by picture electrodes arranged on the facing surfaces of the supporting plates, and a system of row electrodes and column electrodes for driving the picture elements, the column electrodes connected to outputs of multiplex circuits which switch the column electrodes between the data signals to be displayed and an auxiliary signal so as to bring the liquid crystal element to an extreme state prior to application of the data signal; a control and synchronization circuit, which circuit, simultaneously with a selection voltage on a row of picture elements to be displayed, first causes an auxiliary signal to appear on the column electrodes via the multiplex circuits, which signal has a sufficient duration and amplitude to bring a picture element to an extreme state, and which circuit subsequently causes data signals to appear on the column electrodes, characterized in that the auxiliary signal is presented to the picture elements via active switching elements during at least a first part of a line selection period and in that the picture elements are connected to the column electrodes via the same switching elements during a second part of the line selection period in order to present data signals to the picture elements, and further characterized in that the period during which the data signals are presented to the column electrodes is short with represent to the switching period of the ferro-electric liquid crystal.

Claim 17

A display device as claimed in claim 14, characterized in that the data signals are presented during at most half the switching period of the ferro-electro-optical display medium.

Claim 18

A display device as claimed in claim 14, characterized in that the multiplex circuits provide the column electrodes with data voltages during at most half a line section period.