Method and apparatus for driving capacitive display device

A method for driving a capacitive display device, which includes a capacitive display layer intervening between a plurality of scanning electrodes and a plurality of data electrodes arranged in mutually intersecting perpendicular directions, the method comprising the steps of:

• applying data pulses to the data electrodes;
• and
• applying writing pulses to the scanning electrodes in sequence of the scanning electrodes, wherein
• the data pulses applied to the data electrodes having ramp waveforms gradually increasing in voltage level during a rising period of the data pulse, and a pulse width of the data pulses is generally varied dependent upon sequential activation of each corresponding scanning electrode in the sequence of the scanning electrode.

An apparatus for driving a capacitive display device comprising:

• a capacitive display layer disposed between a layer containing a plurality of data electrodes and a layer containing a plurality of scanning electrodes;
• a DC power supply;
• impedance converting means possessing an impedance corresponding to a control signal voltage level, connected in series between the DC power supply and the plurality of data electrodes, for varying the impedance between the DC power supply and the plurality of data electrodes;
• control signal generating means for generating control signals including a modulation voltage and corresponding current, the modulation voltage and corresponding current both sequentially varying in magnitude along a time duration within a predetermined period, dependent upon a desired gradation, and for applying the control signals to the impedance converting means to vary the impedance in accordance with the control signals;
• and
• switching means for passing the current from the impedance converting means to the capacitive display layer through the plurality of data electrodes, only for a time corresponding to the desired gradation in each predetermined period, and for switching off the current for the remaining time in each predetermined period.

A method for driving a capacitive display device, which includes a capacitive display layer intervening between a plurality of scanning side electrodes and a plurality of data side electrodes arranged in mutually intersecting perpendicular directions, said method comprising the steps of:

• applying ramp data pulses, varied in pulse width corresponding to gradation of display data, to the plurality of data side electrodes;
• and
• applying writing pulses, sequentially, to each of the plurality of scanning side electrodes, wherein
• the pulse width of each of the ramp data pulses applied to the data electrodes are sequentially further varied in pulse width, beyond that corresponding to gradation display data, according to sequential location of a corresponding scanning electrode in the scanning sequence of the scanning electrodes, and wherein a degree of pulse width variation is selected so that picture elements corresponding to the same gradation of display data are identical in brightness.

An apparatus for driving capacitive display device comprising:

• a first capacitive display layer intervening between a plurality of first electrodes and a plurality of second electrodes opposing said plurality of first electrodes;
• first electrode driving means for periodically applying a predetermined first potential remaining at a substantially constant voltage level for a predetermined time duration, sequentially, to the plurality of first electrodes;
• second electrode driving means for applying ramp pulses, rising in voltage level over a predetermined time duration, each of a varied pulse width persisting for a driving period, correlated to a predetermined gradation, to each of the plurality of second electrodes;
• detecting means for detecting positional location of each of the plurality of first electrodes, sequentially, relative to the second electrode driving means;
• and
• delay means for delaying each pulse width varied ramp pulse by an amount based upon the detected positional location of each corresponding first electrode, sequentially, so that the persisting driving period for each of the plurality of second electrodes, at a position remote from the second electrode driving means, is longer in time than the persisting driving period of the second electrodes at a position closer to the second driving means, for each gradation based upon each detected positional location, to alleviate line resistence effects and create uniform display for each gradation level.

A method for driving a capacitive display device, which includes a capacitive display layer intervening between a plurality of scanning side electrodes and a plurality of data side electrodes arranged in mutually intersecting perpendicular directions, said method comprising the steps of:

• providing each of the plurality of data side electrodes with a ramp modulation voltage, via one of a plurality of data side electrode drivers, varied in pulse width depending on gradation display data from one side of the plurality of electrodes with respect to another side of the plurality of electrodes, being mutually opposite with respect an extending direction of the plurality of data side electrodes;
• providing the plurality of scanning side electrodes, sequentially, with a substantially rectangular pulse writing voltage;
• detecting positional location of each of the plurality of first electrodes, sequentially, relative to each of the plurality of data side electrode drivers;
• and
• delaying each pulse width varied ramp modulation voltage by an amount based upon the detected positional location of each corresponding first electrode, sequentially, so that the pulse width is gradually decreased or increased with respect to the ramp modulation voltage data pulse, which sequentially increases in voltage level over time, applied from each one of the plurality of data side electrodes based upon the detected positional location, the pulse width being gradually increased or decreased based upon the detected positional location so as to maintain a complementary relationship between the pulse width variations with respect to the ramp modulation voltage applied to the one side and the ramp modulation voltage applied to the other side of the plurality of data side electrodes, a degree of such change being selected so that picture elements corresponding to the same display data may be identical in brightness.

An apparatus for driving a capacitive display device comprising:

• a capacitive display layer intervening between a plurality of first electrodes to be scanned and a plurality of second electrodes, extending in a perpendicular direction with respect to the plurality of first electrodes and divided into a plurality of individual groups;
• first electrode driving means for driving the plurality of first electrodes by periodically applying predetermined potentials, sequentially, to the plurality of first electrodes;
• a plurality of second electrode driving means, one corresponding to each of the individual groups of the plurality of second electrodes, each for applying a ramp pulse with a pulse width persisting for the driving period corresponding to a predetermined gradation and a voltage level gradually increasing for the driving period, to the plurality of second electrodes, and wherein predetermined second potentials, of which a potential difference from the predetermined first potential activates the capacitive display layer, is applied;
• detecting means for detecting positional location of each of the plurality of first electrodes, sequentially, relative to each of the plurality of second electrode driving means;
• and
• a plurality of delay means, one corresponding to each of the plurality of second electrode driving means, each for delaying a corresponding one of the pulse width modulated varied ramp voltage by an amount based upon the detected positional location of each corresponding first electrode, sequentially the second electrode driving means corresponding to a first group of the plurality of individual groups and the second electrode driving means corresponding to another of the plurality of individual groups contain the second electrode driving means individually arranged at opposite ends of the second electrodes.

An apparatus for driving a capacitive display device comprising:

• a capacitive display layer disposed between a layer containing a plurality of data electrodes and a layer containing a plurality of scanning electrodes;
• scanning electrode driving means for periodically applying a predetermined first potential remaining at substantially constant voltage level for a predetermined time duration, sequentially, to the plurality of scanning electrodes;
• data electrode driving means including,
• a DC power supply,
• impedance converting means possessing an impedance corresponding to a control signal voltage level, connected in series between the DC power supply and the plurality of data electrodes, for varying the impedance between the DC power supply and the plurality of data electrodes,
• control signal generating means for generating control signals including a modulation voltage and corresponding current, the modulation voltage and corresponding current both sequentially varying in magnitude along a time duration within a predetermined period, dependent upon a desired gradation, and for applying the control signals to the impedance converting means to vary the impedance in accordance with the control signals, and switching means for passing the current from the impedance converting means to the capacitive display layer through the plurality of data electrodes, only for a time corresponding to the desired gradation in each predetermined period, and for
• switching off the current for the remaining time in each predetermined period;
• the data electrode driving means further including,
• detecting means for detecting positional location of each of the plurality of scanning electrodes, sequentially, relative to the data electrode driving means, and
• delay means for delaying each control signal by an amount based upon the detected positional location of each corresponding scanning electrode, sequentially, so that the persisting driving period for each of the plurality of second electrodes, at a position remote from the second electrode driving means, is longer in time than the persisting driving period of the second electrodes at a position closer to the second driving means, for each gradation based upon each detected positional location, to alleviate line resistance effects and create uniform display for each gradation level.