Claims
- 1. A method of driving a ferroelectric liquid crystal device matrix in a time-division multiplex mode, comprising the steps of: applying strobing signals cyclically to strobe lines coupled to two-state liquid crystal elements of the display; and applying data signals selectively to data lines coupled to the elements; wherein each strobing signal comprises, during each frame period, only two strobe pulse periods, during which there are a first pule of one polarity followed by a second pulse of the opposite polarity and of different amplitude and/or duration from the first pule, each strobing signal including, between successive frame periods, a dc voltage which is effective during a period between the end of the second strobe pulse of a said strobing signal and the beginning of the first strobe pulse of the next strobing signal applied to the same strobe line to substantially cancel a dc voltage level resulting from the difference between the amplitudes and/or durations of the first and second strobe pulses, and which dc voltage will not switch the liquid crystal elements during said period; wherein the data signals comprise selectively a first data signal or a second data signal, said first data signal being operative in combination with the strobing signal to set a selected liquid crystal element in a first one of its states, and said second data signal being operative in combination with the strobing signal to set the selected liquid crystal element in the other of its states; and wherein one or each of the first and second data signals comprises two consecutive pulses of opposite polarities, there being only two data pulse periods in a frame period, said data pulse periods being substantially coincident with the strobe pulse periods.
- 2. A method as claimed in claim 1, wherein said first data signal comprises two consecutive pulses of mutually opposite polarities and of substantially equal amplitudes, and said second data signal comprises two consecutive pulses of opposite polarities to the pulses of said first data signal and of substantially equal amplitudes.
- 3. A method as claimed in claim 1, wherein said first data signal comprises a constant dc level, and said second data signal comprises two consecutive pulses of polarities opposite to those of the pulses of the strobing signal.
- 4. A method as claimed in claim 1, wherein said first data signal comprises two consecutive pulses of the same polarities as the pulses of the strobing signal, and said second data signal comprises a constant dc level.
- 5. A method as claimed in claim 1, wherein said first and second pulses of the strobing signal are of mutually different time durations.
- 6. A method as claimed in claim 1, wherein each first and second data signal comprises two pulses of mutually opposite polarities and of mutually different time durations.
- 7. A method as claimed in claim 1, wherein the strobing signal and/or each first and second data signal comprises two pulses of mutually opposite polarities separated by a period of zero voltage.
- 8. A method as claimed in claim 1, wherein a relatively high-frequency ac voltage is superimposed on the strobing signal and/or the data signal.
- 9. Apparatus for driving a ferroelectric liquid crystal device matrix in a time-division multiplex mode, comprising the steps of: applying strobing signals cyclically to strobe lines coupled to two-state liquid crystal elements of the display; and applying data signals selectively to data lines coupled to the elements; wherein each strobing signal comprises, during each frame period, only two strobe pulse periods, during which there are a first pulse of one polarity followed by a second pulse of the opposite polarity and of different amplitude and/or duration from the first pulse, each strobing signal including, between successive frame periods, a dc voltage which is effective during a period between the end of the second strobe pulse of a said strobing signal and the beginning of the first strobe pulse of the next strobing signal applied to the same strobe line to substantially cancel a dc voltage level resulting from the difference between the amplitudes and/or durations of the first and second strobe pulses, and which dc voltage will not switch the liquid crystal elements during said period; wherein the data signals comprise selectively a first data signal or a second data signal, said first data signal being operative in combination with the strobing signal to set a selected liquid crystal element in a first one of its states, and said second data signal being operative in combination with the strobing signal to set the selected liquid crystal element in the other of its states; and wherein one of each of the first and second data signals comprises two consecutive pulses of opposite polarities, there being only two data pulse periods in a frame period, said data pulse periods being substantially coincident with the strobe pulse periods.
Priority Claims (1)
Number |
Date |
Country |
Kind |
8719078 |
Aug 1987 |
GBX |
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Parent Case Info
This is a continuation of application Ser. No. 07/340,296, filed on Apr. 5, 1989, now abandoned.
US Referenced Citations (6)
Foreign Referenced Citations (4)
Number |
Date |
Country |
0229647 |
Jul 1987 |
EPX |
0257131 |
Sep 1987 |
JPX |
0249130 |
Oct 1988 |
JPX |
0172819 |
Jul 1989 |
JPX |
Continuations (1)
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Number |
Date |
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Parent |
340296 |
Apr 1989 |
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