Method of driving surface-stabilized ferroelectric liquid crystal display element for increasing the number of gray scales
AssigneeFujitsu Limited
InventorsAkihiro Mochizuki, Shigeo Kasahara, Katsusada Motoyoshi
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Abstract
A method for driving a surface-stabilized ferroelectric liquid crystal display element uses a selection voltage, a half-selection voltage, and a non-selection voltage. A relative ratio between the selection voltage, half-selection voltage, and non-selection voltage of a drive signal is changed, or absolute levels of the selection voltage, half-selection voltage, and non-selection voltage are changed. Consequently, a plurality of gradations of the surface-stabilized ferroelectric liquid crystal display element can be obtained.
Claims22
A method of directly driving a surface-stabilized ferroelectric liquid crystal in a simple matrix liquid crystal display which comprises a first substrate including a plurality of first electrodes, a second substrate including a plurality of second electrodes disposed orthogonally to said first electrodes and defining cross portions therebetween, and a plurality of surface-stabilized ferroelectric liquid crystal display elements, a respective surface-stabilized ferroelectric liquid crystal element being provided at each cross portion between said first electrodes and said second electrodes, each surface-stabilized ferroelectric liquid crystal display element being driven by a drive signal, the method comprising:
- a) defining plural drive signal levels of the drive signal in accordance with selectable, plural, different combinations of respective levels of a selection voltage, a half-selection voltage, and a non-selection voltage, the plural different combinations comprising plural, different relative ratios of the respective levels of the selection, half-selection and non-selection voltages and respectively displaying plural different gradations of a surface-stabilized ferroelectric liquid crystal display element to which the drive signal is applied;
- b) setting a relative ratio of the respective levels of the selection voltage, the half-selection voltage, and the non-selection voltage of the drive signal for a corresponding frame interval, selected as one of every individual frame and every several frames, to display the respective gradation of the surface-stabilized ferroelectric liquid crystal display element, the relative ratio of the respective levels of the selection voltage, the half-selection voltage, and the non-selection voltage of the drive signal, as set, being maintained during the corresponding frame interval and being selectively changeable for successive corresponding frame intervals;
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- b) applying the drive signal having the set relative ratio to the corresponding surface-stabilized ferroelectric liquid crystal display element to display the respective gradation during the corresponding frame interval.
A method of directly driving a surface-stabilized ferroelectric liquid crystal display element in a simple matrix liquid crystal display which comprises a first substrate including a plurality of first electrodes, a second substrate including a plurality of second electrodes disposed orthogonally to and displaced from said first electrodes, and a plurality of surface-stabilized ferroelectric liquid crystal display elements, a respective surface-stabilized ferroelectric liquid crystal element being provided at each cross portion between said first electrodes and said second electrodes, the method comprising the steps of:
- a) defining, in common and for each of the surface-stabilized ferroelectric liquid display crystal elements of the simple matrix liquid crystal display, an operative range of variable light transmittance from a minimum level of light transmittance to a maximum level of light transmittance;
- b) defining a drive signal having plural different values determined by selectable different combinations, and corresponding different ratios, of respective, different voltage levels of a selection voltage, a half-selection voltage and a non-selection voltage;
- c) correlating the plural different drive signal values to corresponding different gradations of the operative range of variable light transmittance, in common for the surface-stabilized ferroelectric liquid crystal display elements of the display;
- d) defining a frame interval as a selected one of an individual frame and a group of several frames;
- e) for each of successive frame intervals and for each display element of the display, defining the drive signal value for a respective display element in accordance with selecting the combination of respective, different voltage levels having the corresponding ratio correlated to the light transmittance gradation to be displayed in the respective frame interval;
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- f) applying a drive signal having the defined drive signal value to the respective display element during the corresponding frame interval and while maintaining the selected combination, and ratio, of the respective voltage levels of the selection, half-selection and non-selection voltages, and producing the correlated light transmission gradation in the respective display element and for the respective frame interval.
Dependencies are inferred from the claim text.