Driving method for optical modulation device using ferroelectric liquid crystal
First Claim
1. A driving method for an optical modulation device comprising scanning electrodes, signal electrodes disposed intersecting the scanning electrodes so as to form a pixel at each intersection of the scanning electrodes and signal electrodes, and an optical modulation material disposed between the scanning electrodes and the signal electrodes and assuming different orientation states when supplied with voltages of different polarities exceeding threshold voltages;
- said driving method comprising the steps of;
writing in all or prescribed pixels on a selected scanning electrode of the scanning electrodes in a writing period including at least four phases;
applying voltages of mutually opposite polarities in the first phase and the last phase, having an amplitude not exceeding the threshold voltages of said optical modulation material, to all of the pixels on a nonselected scanning electrode; and
applying to said selected scanning electrode two voltage signals having the same amplitude and mutually opposite polarities, a voltage signal having a smaller amplitude than said same amplitude, and a voltage signal 0 voltage, respectively, with respect to the potential of a nonselected scanning electrode in the writing period including said at least four phases, wherein said voltage signal of 0 voltage is applied in the last phase of said at least four phases.
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Abstract
An optical modulation device includes scanning electrodes and signal electrodes disposed opposite to and intersecting with the signal electrodes, and an optical modulation material disposed between the electrodes, a pixel being formed at each intersection of the electrodes and showing a contrast depending on the polarity of a voltage applied thereto. The device is driven by a method including, in a writing period for writing in all or prescribed pixels among the pixels on a selected scanning electrode, a first phase for applying a voltage of one polarity having an amplitude exceeding a first threshold voltage of the optical modulation material to the all or prescribed pixels, and a second phase for applying a voltage of the other polarity having an amplitude exceeding a second threshold voltage of the optical modulation material to a selected pixel and applying a voltage not exceeding the threshold voltages of the optical modulation material to the other pixels, respectively among the all or prescribed pixels. The maximum duration of a continually applied voltage of the same polarity applied to a pixel on a scanning electrode is 2.5 times the duration of the first phase in the writing period.
14 Citations
11 Claims
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1. A driving method for an optical modulation device comprising scanning electrodes, signal electrodes disposed intersecting the scanning electrodes so as to form a pixel at each intersection of the scanning electrodes and signal electrodes, and an optical modulation material disposed between the scanning electrodes and the signal electrodes and assuming different orientation states when supplied with voltages of different polarities exceeding threshold voltages;
- said driving method comprising the steps of;
writing in all or prescribed pixels on a selected scanning electrode of the scanning electrodes in a writing period including at least four phases; applying voltages of mutually opposite polarities in the first phase and the last phase, having an amplitude not exceeding the threshold voltages of said optical modulation material, to all of the pixels on a nonselected scanning electrode; and applying to said selected scanning electrode two voltage signals having the same amplitude and mutually opposite polarities, a voltage signal having a smaller amplitude than said same amplitude, and a voltage signal 0 voltage, respectively, with respect to the potential of a nonselected scanning electrode in the writing period including said at least four phases, wherein said voltage signal of 0 voltage is applied in the last phase of said at least four phases. - View Dependent Claims (2, 3, 4, 5, 6, 7)
- said driving method comprising the steps of;
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8. An optical modulation apparatus comprising:
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an optical modulation device comprising scanning electrodes, signal electrodes disposed intersecting the scanning electrodes so as to form a pixel at each intersection of the scanning electrodes and signal electrodes, and an optical modulation material disposed between the scanning electrodes and the signal electrodes and assuming a first stable optical state in response to a voltage of one polarity and a second stable optical state in response to a voltage of another polarity exceeding respective threshold voltages, and (b) drive means for; (b1) sequentially applying to the scanning electrodes a scanning selection signal comprising a pulse of one polarity in a first phase, a pulse of another polarity in a second phase and a pulse of said one polarity in a third phase, and (b2) writing in pixels on a selected scanning electrode by, in the first phase, applying to the signal electrodes a voltage signal which provides a voltage of one polarity simultaneously causing the first optical state at the pixels on the selected scanning electrode in combination with the scanning selection signal to erase the pixels on the selected scanning electrode, in the second phase, selectively applying to the signal electrodes a pulse of one polarity or a pulse of another polarity which provides a voltage of another polarity causing the second optical state or a voltage maintaining the erased state respectively in combination with the scanning selection signal at associated pixels on the selected scanning electrode to write in the associated pixels, and in the third phase, applying to the signal electrodes voltage signals which provide voltages respectively opposite to the voltages applied to the associated pixels on the selected scanning line in the second phase so as to retain the written states at the associated pixels, the polarities of the pulses being defined with respect to a voltage applied to a non-selected scanning electrode, and (b3) applying an alternating voltage to pixels on a non-selected scanning electrode so as to retain the written states of the pixels formed when they have been placed on a selected scanning electrode. - View Dependent Claims (9, 10, 11)
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Specification