Method of driving optical modulation device using ferroelectric liquid crystal

A driving method for an optical modulation device according to claim 6, wherein said liquid crystal having a chiral-smectic phase has a C-phase or H-phase.

In a driving method for an optical modulation 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 a ferroelectric liquid crystal disposed between said group of scanning electrodes and said group fo signal electrodes, the improvement comprising:

• (a) in a first phase, applying a voltage of one polarity, allowing said ferroelectric liquid crystal to be oriented to a first stable state, between a scanning electrode selected from said group of scanning electrodes and said group of signal electrodes, and
• (b) in a second phase, applying a voltage of the other polarity, allowing said ferroelectric liquid crystal oriented to said first stable state to be oriented to a second stable state, between said selected scanning electrode and a signal electrode selected from said group of signal electrodes.

In a driving method for an optical modulation device having a matrix electrode arrangement comprising a group of scanning electrodes, and a group of signal electrodes oppositely spaced from the group of scanning electrodes, wherein scanning signals are selectively applied sequentially and periodically to said group of scanning electrodes and information signals are selectively applied to said group of signal electrodes in synchronism with said scanning signals, thereby 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 said groups of scanning electrodes and signal electrodes;

• the improvement wherein
• before or after an information signal is applied to a selected signal electrode among the group of signal electrodes in synchronism with a scanning signal applied to a selected scanning electrode among the group of scanning electrodes an auxiliary signal different from the information signal is applied to the selected signal electrode in synchronism with the scanning signal.

A driving method for an optical modulation device comprising picture elements arranged in a plurality of rows, each picture element comprising a pair of oppositely spaced electrodes and an optical modulation material interposed therebetween having a first and a second stable state depending on an electric field applied thereto, said driving method comprising addressing said plurality of picture elements by applying a scanning signal row by row, wherein

• a first voltage signal of one polarity orienting the optical modulation material to the first stable state is applied to a picture element in an addressed row of picture elements,
• a second voltage signal of the other polarity orienting the optical modulation material to the second stable state is applied to another picture element in the addressed row of picture elements, and
• a third voltage signal allowing the optial modulation material to maintain its first or second stable state is applied to non-addressed rows of picture elements.

A driving method for a liquid crystal device comprising picture elements arrange in a plurality of rows, each picuture element comprising a pair of oppositely spaced electrodes and a ferroelectric liquid crystal interposed therebetween, said driving method comprising sujecting said plurality of rows of picture elements to application of voltage, wherein

• a first voltage signal orienting the ferroelectric liquid crystal to the first stable state is applied to at least a part of the picture elements in phase t.sub.1 and
• a second voltage signal orienting the ferroelectric liquid crystal to the second stable state is applied to selected picture elements among said at least a part of the picture elements in phase t.sub.2.

A driving method for a liquid crystal device comprising a plurality of picture elements arranged in a plurality of rows, each picture element comprising a pair of oppositely spaced electrodes and a ferroelectric liquid crystal disposed between the electrodes assuming a first and a second stable state and having threshold voltages V.sub.th1 and -V.sub.th2 for the first and second stable states, respectively, said driving method comprising:

• (a) in a first phase, applying row by row a first voltage signal for orienting the ferroelectric liquid crystal to the first stable state and a second voltage signal not exceeding the threshold voltages V.sub.th1 and -V.sub.th2 selectively between the oppositely spaced electrodes of the picture elements, and
• (b) in a second phase, applying row by row a third voltage signal for orienting the ferroelectric liquid crystal to the second stable state and a fourth voltage signal not exceeding the threshold voltages V.sub.th1 and -V.sub.th2 selectively between the oppositely spaced electrodes of the picture elements.

A driving method for a liquid crystal device comprising a plurality of picture elements arranged in a plurality of rows, each picture element comprising a pair of oppositely spaced electrodes and a ferroelectric liquid crystal disposed between the electrodes adsuming a first or a second stable state and having threshold voltages V.sub.th1 and -V.sub.th2 for the first and second stable states, respectively, said driving method comprising:

• (a) in a first phase, applying row by row a first voltage signal for orienting the ferroelectric liquid crystal to the first stable state to at least a part of the picture elements, and
• (b) in a second phase, applying row by row a second voltage signal for orienting the ferroelectric liquid crystal to the second stable state to a selected picture element among said at least a part of the picture elements wherein the ferroelectric liquid crystal has been oriented to the first stable state, and applying a third voltage signal not exceeding the threshold voltages V.sub.th1 and -V.sub.th2 to a non-selected picture element among said at least a part of the picture elements in the addressed row.

In a driving method for an optical modulation device comprising a plurality of picture elements, each picture element comprising a pair of oppositely spaced electrodes and an optical modulation material showing a first stable state and a second stable state depending on an electric field applied thereto and having a first threshold voltage and a second threshold voltage for the first and second stable state, respectively;

• said driving method comprising:
• (a) in a first phase, applying a first voltage signal of one polarity exceeding the first threshold voltage to the plurality of picture elements, thereby to orient bring the picture elements to a state based on the first stable state of the optical modulation material, and
• (b) in a second phase, applying a second voltage signal of the other polarity exceeding the second threshold voltage to a selected picture element among the plurality of picture elements thereby to orient bring the selected picture element to a state based on the second stable state of the optical modulation material, and applying a third voltage signal to non-selected picture elements for allowing the non-selected picture elements to retain the state based on the first stable state of the optical modulation material.

A driving method for an optical modulation device comprising a plurality of picture elements arranged in a plurality of rows, each picture element comprising a pair of oppositely spaced electrodes and a ferroelectric liquid crystal disposed between the electrodes showing a first stable state and a second stable state depending on an electric field applied, said driving method comprising the steps of:

• (a) orienting the ferroelectric liquid crystal at the picture elements on a selected row selectively to either the first or second stable state by applying a voltage of one polarity or the other polarity, respectively, to write in the picture elements, the selection of rows being conducted row by row, and
• (b) applying an alternating voltage signal lower than a threshold voltage of the ferroelectric liquid crystal at the picture elements on non-selected rows, in parallel with the step (a).

In a driving method for an optical modulation device comprising a plurality of picture elements arranged in a plurality or rows, each picture element comprising a pair of oppositely spaced electrodes and a ferroelectric liquid crystal interposed between the electrodes showing a first stable state and a second state depending on an electric field applied thereto,

• the improvement comprising the steps of:
• (a) orienting the ferroelectric liquid crystal at a selected picture element in a selected row to its first stable state by applying a voltage of one polarity or second stable state by applying a voltage of the other polarity to write in the picture element, and
• (b) applying to the written picture element a voltage signal for preventing the inversion of the orientd state of the ferroelectric liquid crystal to another state when the written picture element is placed in a non-selected row, said voltage signal being set to a value between a threshold voltage -V.sub.th2 (for said second stable state) and a threshold voltage V.sub.th1 (for said first stagle state) of said ferroelectric liquid crystal.

In a driving method for an optical modulation device comprising a plurality of picture elements each comprising an optical modulation material showing a first stable state and a second stable state depending on an electric field applied;

• said driving method comprising:
• (a) in a first phase, applying to a picture element a first signal for orienting the optical modulation material at the picture element to the first stable state, and
• (b) in a second phase, applying to the picture element a second signal for providing a mixed state of the optical modulation material oriented to the first stable state and the optical modulation material oriented to the second stable state corresponding to a prescribed gradation.

In a driving method for an optical modulation 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 assuming a first stable state and a second stable state depending on an electric field applied thereto disposed between said group of scanning electrodes and said group of signal electrodes, the improvement comprising:

• (a) in a first phase, applying a first voltage signal allowing said optical modulation material to be oriented to a first stable state between a scanning electrode selected from said group of scanning electrodes and said group of signal electrodes, and
• (b) in a second phase, applying a second voltage signal allowing the optical modulation material oriented to the first stable state to be partially re-oriented to the second stable state to result in the first and second stable states in accordance with a prescribed gradation between said selected scanning electrode and a signal electrode selected from said group of signal electrodes.

A driving method for an optical modulation device comprising a plurality of picture elements arranged in a plurality of rows, each picture element comprising a pair of oppositely spaced electrodes and an optical modulation material disposed between the electrode assuming a first or a second stable state depending on an electric field applied, said driving method comprising:

• (a) in a first phase, applying a first voltage signal for orienting the optical modulation material to the first stable state between the oppositely spaced electrodes of selected picture elements in a plurality of rows, and
• (b) in a second phase, applying row by row a second voltage signal for orienting the optical modulation material to the second stable state and a third voltage signal not exceeding the threshold voltages selectively between the oppositely spaced electrodes of the selected picture elements, thereby to rewrite the selected picture elements among said plurality of picture elements.

A driving method for a liquid crystal device comprising a plurality of picture elements arranged in a plurality of rows and columns and capable of defining therein a rewriting region and a non-rewriting region, each picture element comprising a pair of oppositely spaced electrodes and a ferroelectric liquid crystal disposed between the electrodes assuming a first or a second stable state and having threshold voltages V.sub.th1 and -V.sub.th2 for the first and second stable states, respectively, said driving method comprising:

• (a) in a first phase, applying row by row a first voltage signal for orienting the ferroelectric liquid crystal to the first stable state and a second voltage signal not exceeding the threshold voltages V.sub.th1 and -V.sub.th2 between the oppositely spaced electrodes of the picture elements in the rewriting region, and
• (b) in a second phase, applying row by row a third voltage signal for orienting the ferroelectric liquid crystal to the second stable state and a fourth voltage signal not exceeding the threshold voltages V.sub.th1 and -V.sub.th2 selectively between the oppositely spaced electrodes of the picture elements in the rewriting region, thereby to rewrite the picture elements in the rewriting region.

In a driving method for an optical modulation device comprising a plurality of picture elements arranged along a plurality of scanning lines and a plurality of signal lines, each picture element comprising an optical modulation material showing a first stable state and a second stable state depending on an electric field applied, the improvement comprising:

• (a) defining a rewriting region and a non-rewriting region in a picture ara constituted by the plurality of picture elements,
• (b) sequentially applying a scanning signal to scanning lines connected to the picture elements in the rewriting region, and selectively applying signals based on rewriting information to the signal lines connected to the picture elements in the rewriting region, and
• (c) applying to the picture elements in the non-rewriting region a signal for not changing the display states of the picture elements.