Canon Kabushiki Kaisha

Syuzo Kaneko

Junichiro Kanbe

Kazuharu Katagiri

A driving method for an optical modulation device is applicable to driving of an optical modulation device, e.g. a liquid crystal device having a matrix electrode arrangement comprising a group of scanning electrodes, a group of signal electrodes oppositely spaced from the group of scanning electrodes, and an optical modulation material (e.g. a liquid crystal) showing bistability with respect to an electric filed applied thereto disposed between the groups of scanning electrodes and signal electrodes. The driving method is featured by applying a voltage allowing the liquid crystal having bistability to be oriented to a first stable state (one optically stable state) between a selected scanning electrode of the group of scanning electrodes and a selected signal electrode of the group of signal electrodes, and by applying a voltage allowing the liquid crystal having bistability to be oriented to a second stable state (the other optically stable state) between the selected scanning electrodes and non-selected signal electrodes; or by applying a voltage allowing the optical modulation material having bistabity to be oriented to a first stable state between a selected scanning electrode and the group of signal electrodes, applying a voltage allowing the liquid crystal oriented to the first stable state to be oriented to a second stable state between the selected scanning electrode and a selected signal electrode, and applying a voltage set to a value between a threshold voltage -V.sub.th2 (for the second stable state) and a threshold voltage V.sub.th1 (for the first stable state) between non-selected scanning electrodes and the group of signal electrodes.

Method of driving optical modulation device

A liquid crystal apparatus comprises a liquid crystal device comprising a group of scanning electrodes and a group of signal electrodes intersecting each other to form an electrode matrix, and a chiral smectic liquid crystal disposed in a non-helical alignment state so as to form a picture element at each intersection of the scanning electrodes and the signal electrodes. Drive means are provided for: (a) applying a scanning selection signal and a scanning non-selection signal to the scanning electrodes, the scanning selection signal comprising a voltage of one polarity and a voltage of the other polarity, respectively with reference to a voltage level of the scanning nonselection signal, and being applied in a period for selecting one scanning electrode, (b) in a period of applying the voltage of one polarity, applying signals to the signal electrodes for causing one orientation state of the chiral smectic liquid crystal, so as to non-selectively erase the picture elements on a scanning electrode to which the scanning selection signal is applied, and (c) periodically applying the scanning selection signal to the scanning electrodes.

A liquid crystal apparatus includes a liquid crystal device having a group of scanning lines and a group of signal lines intersecting each other to form a matrix of picture elements, and a chiral smectic liquid crystal disposed so as to form the picture elements. The device is driven by: (a) applying a scanning selection signal and a scanning non-selection signal to the scanning lines, the scanning selection signal comprising a voltage of one polarity and a voltage of the other polarity, respectively with reference to a voltage level of the scanning non-selection signal, (b) applying a data signal having a voltage determined according to an environmental temperature for causing one orientation state of the chiral smectic liquid crystal selectively to the signal lines in a period of applying the voltage of one polarity to a scanning line and applying a data signal having a voltage determined according to an environmental temperature for causing another orientation state of the chiral smectic liquid crystal selectively to the signal lines in a period of applying the voltage of the other polarity to the scanning line, and (c) periodically applying the scanning selection signal to the scanning lines.

A liquid crystal apparatus includes a liquid crystal device having a group of scanning lines and a group of signal lines intersecting each other to form a matrix of picture elements, and a chiral smectic liquid crystal disposed so as to form the picture elements. The device is driven by: (a) applying a scanning selection signal and a scanning non-selection signal to the scanning lines, (b) applying data signals having a predetermined voltage determined according to an environmental temperature and including a gradation data signal to the signal lines so as to provide a selected picture element at an intersection of a selected scanning line receiving the scanning selection signal and a selected signal electrode with a ratio between an area occupied with one orientation state and an area occupied by another orientation state, respectively of the chiral smectic liquid crystal, depending on given gradation data, and (c) periodically applying the scanning selection signal to the scanning lines.

A liquid crystal apparatus includes a liquid crystal device having a group of scanning electrodes and a group of signal electrodes intersecting each other to form an electrode matrix, and a chiral smectic liquid crystal having a threshold voltage varying depending on a voltage pulse width disposed so as to form a picture element at each intersection of the scanning electrodes and the signal electrodes. The electrodes are driven by (a) applying a scanning selection signal and a scanning non-selection signal to the scanning electrodes, (b) applying data signals to the signal electrodes so as to apply a voltage to a selected picture element at an intersection of a selected scanning electrode receiving the scanning selection signal and a selected signal electrode, the voltage applied to the selected picture element being at least two times a voltage applied to a non-selected picture element at an intersection of a non-selected scanning electrode receiving the scanning non-selection signal and a selected or non-selected signal electrode, (c) periodically applying the scanning selection signal to the scanning electrodes, and (d) setting a voltage level of the voltage according to a local environmental temperature.

A driving method for an optical modulation device is applicable to driving of an optical modulation device, e.g. a liquid crystal device having a matrix electrode arrangement comprising a group of scanning electrodes, a group of signal electrodes oppositely spaced from the group of scanning electrodes, and an optical modulation material (e.g. a liquid crystal) showing bistability with respect to an electric filed applied thereto disposed between the groups of scanning electrodes and signal electrodes. The driving method is featured by applying a voltage allowing the liquid crystal having bistability to be oriented to a first stable state (one optically stable state) between a selected scanning electrode of the group of scanning electrodes and a selected signal electrode of the group of signal electrodes, and by applying a voltage allowing the liquid crystal having bistability to be oriented to a second stable state (the other optically stable state) between the selected scanning electrodes and non-selected signal electrodes.

A liquid crystal apparatus comprises a liquid crystal device comprising a group of scanning electrodes and a group of signal electrodes intersecting each other to form an electrode matrix, and a chiral smectic liquid crystal disposed so as to form a picture element at each intersection of the scanning electrodes and the signal electrodes. Drive means is also provided for: (a) applying a scanning selection signal and a scanning non-selection signal to the scanning electrodes, the scanning selection signed comprising a voltage of one polarity and and a voltage of the other polarity, respectively with reference to a voltage level of the scanning non-selection signal, and being sequentially applied to the respective scanning electrodes; (b) in a period of applying the one or the other polarity, applying signals including a first signal and a second signal to the signal electrodes for causing the one or another orientation state of the chiral smectic liquid crystal; (c) applying to picture elements a DC bias voltage equal to a voltage difference between the voltage level of the scanning non-selection signal and a voltage applied to a signal electrode not receiving the data signal; and (d) periodically applying the scanning selection signal to the scanning electrodes.

A liquid crystal apparatus comprises a liquid crystal device including scanning electrodes and signal electrodes intersecting each other, and a chiral smectic liquid crystal disposed therebetween. The chiral smectic liquid crystal assumes a first orientation state when supplied with a pulse voltage of one polarity exceeding a first threshold voltage, a second orientation state when supplied with a pulse voltage of the other polarity exceeding a second threshold voltage, and a third orientation state when released from application of the pulse voltage of one or the other polarity. Drive means periodically applies the scanning selection signal to the scanning electrodes, and controls the application of the scanning selection signal, the scanning non-selection signal and the data signals so as to apply the data signals in synchronism with the scanning selection signal, thereby applying the pulse voltage of one or the other polarity as a combination of the information signal and the one or the other voltage signal of the scanning selection signal to the chiral smectic liquid crystal. Drive means also applies an auxiliary signal in combination with the scanning non-selection signal to suppress a change into the third orientation state of the chiral smectic liquid crystal.

A driving method for an optical modulation device is applicable to driving of an optical modulation device, e.g. a liquid crystal device having a matrix electrode arrangement comprising a group of scanning electrodes, a group of signal electrodes oppositely spaced from the group of scanning electrodes, and an optical modulation material (e.g. a liquid crystal) showing histability with respect to an electric field applied thereto disposed between the groups of scanning electrodes and signal electrodes. The driving method is featured by applying a voltage allowing the liquid crystal having histability to be oriented to a first stable state (one optically stable state) between a selected scanning electrode of the group of scanning electrodes and a selected signal electrode of the group of signal electrodes, and by applying a voltage allowing the liquid crystal having histability to be oriented to a second stable state (the other optically stable state) between the selected scanning electrodes and non-selected signal electrodes.

A liquid crystal apparatus comprises a liquid crystal device having scanning electrodes arranged in a matrix with and spaced apart from signal electrodes with a liquid crystal showing different stable states in accordance with different applied voltages and having a memory function disposed therebetween. First drive circuitry selects and sequentially drives the scanning electrodes by application of a scanning selection signal, and second drive circuitry drives the signal electrodes by application of a writing voltage and a first non-writing voltage corresponding to display contents in synchronism with the application of the scanning selection signal. The first drive circuitry applies reset voltages to the pixels of the liquid crystal to make orientation of the liquid crystal's molecules uniform before the selection of the scanning electrode. The amplitude of a writing voltage applied to an intersection of the selected scanning electrode and a selected signal electrode is two or more times that of a first non-writing voltage applied to an intersection of a nonselected scanning electrode and the selected signal electrode.

A driving method is provided for driving an optical modulation device. The device has picture elements arranged in the form of a matrix consisting of a plurality of rows and a plurality of columns defined by the intersections of scanning electrodes and signal electrodes, and a liquid crystal having a memory function. The picture elements in each row are selectively supplied with either a voltage for orienting the liquid crystal to one display state, or another voltage for orienting the liquid crystal to another display state. The method comprises the steps of sequentially and repetitively applying a scanning selection signal to the scanning electrodes, the scanning selection signal comprising a former signal of a first voltage and a latter voltage signal of a second voltage different from the first voltage to one of the scanning electrodes to select a particular scanning electrode, and applying data signals to the signal electrodes, each data signal comprising an information signal for selecting a display state of a picture element on the particular scanning electrode. The picture elements on the particular scanning electrode supplied with the former voltage signal are non-selectively erased into an erased state and a picture element on the particular scanning electrode supplied with the latter voltage signal is placed in either the one display state or another display state depending on the information signal.

An optical modulation apparatus has a matrix electrode arrangement comprising scanning electrodes and signal electrodes oppositely spaced from the scanning electrodes. Scanning signals are selectively applied sequentially and periodically to the scanning electrodes and information signals are selectively applied to the signal electrodes in synchronism with the scanning signals to effect optical modulation of an optical modulation material showing a first stable state and a second stable state with respect to an electric field applied thereto interposed between the scanning and signal electrodes. Before or after an information signal is applied to a selected signal electrode in synchronism with a scanning signal applied to a selected scanning electrode, an auxiliary signal different from the information signal is applied to the selected signal electrode in synchronism with the scanning signal, and an amplitude of a writing voltage applied to an intersection of the selected scanning electrode and the selected signal electrode is two or more times that of a first non-writing voltage applied to an intersection of a non-selected scanning electrode and the selected signal electrode. The amplitudes of the writing voltage and the first non-writing voltage are respectively determined with respect to a reference voltage determined as a difference between a voltage applied to a signal electrode receiving no data signal, and a voltage applied to the non-selected scanning electrode.

Method of driving ferroelectric liquid crystal optical modulation device

A driving method for an optical modulation device is applicable to driving of an optical modulation device, e.g., a liquid crystal device having a matrix electrode arrangement comprising a group of scanning electrodes, a group of signal electrodes oppositely paced from the group of scanning electrodes, and an optical modulation materials showing bistability with respect to an electric field applied thereto disposed between the groups of scanning electrodes and signal electrodes. The driving method is featured by applying a voltage allowing the liquid crystal having bistability to be oriented to a first stable state between a selected scanning electrode of the group of scanning electrodes and a selected signal electrode of the group of signal electrodes, and by applying a voltage allowing the liquid crystal having bistability to be oriented to a second stable state between the selected scanning electrodes and non-selected signal electrodes; or by applying a voltage allowing the optical modulation material having bistability to be oriented to a first stable state between a selected scanning electrode and the group of signal electrodes, applying a voltage allowing the liquid crystal oriented to the first stable state to be oriented to a second stable state between the selected scanning electrode and a selected signal electrode, and applying a voltage set to a value between a threshold voltage -V.sub.th2 (for the second stable state) and a threshold voltage V.sub.th1 (for the first stable state) between non-selected scanning electrodes and the group of signal electrodes.

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Tokyo, Japan

Syuzo Kaneko