US4392718A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Resistive electrode LCD and voltage supply means
Assignee: Ferranti International PLC
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Filing: 1980-12-30
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Granted: 1983-07-12
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Expires: 2000-12-30
Abstract
Abstract A liquid display device comprises two spaced electrodes each having a resistance characteristic such that a potential gradient may be developed across the electrode. A liquid crystal material is located between the two electrodes. Voltage supply means are provided which apply an alternating potential across each electrode, such that the two potentials are of the same frequency, and, preferably, in quadrature with one another.
Inventors
- 👤 John M. Morrison
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 18:25
CPC Classifications
G; G01; G01R; G01R13/00; G01R13/40; G01R13/404; G01R13/407
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
151 words
A display device which includes a pair of spaced electrodes each having a resistance characteristic such that a potential gradient may be developed across the electrode, a pair of terminals on each electrode located such that the potential gradients developed across the two electrodes extend at an angle to one another, a liquid crystal material located between the two electrodes and being of a type which becomes opaque when an electric field is applied across it, voltage supply means operable to apply an alternating potential across each pair of terminals, such that the two potentials are of the same frequency and are out of phase with one another by an angle which determines the form of the display and in which the voltage supply means are arranged to provide, across each electrode, a constant voltage and include means for varying the potential of each terminal with respect to a reference potential.
Claim 2
Dependent Claim
151 words
A display device which includes a pair of spaced electrodes each having a resistance characteristic such that a potential gradient may be developed across the electrode, a pair of terminals on each electrode located such that the potential gradients developed across the two electrodes extend at an angle to one another, a liquid crystal material located between the two electrodes and being of a type which becomes opaque when an electric field is applied across it, voltage supply means operable to apply an alternating potential across each pair of terminals, such that the two potentials are of the same frequency and are out of phase with one another by an angle which determines the form of the display and in which the voltage supply means are arranged to provide, across each electrode, a constant voltage and include means for varying the potential of each terminal with respect to a reference potential.
Claim 3
Dependent Claim
43 words
A display device as claimed in claim 1 in which the electrodes are arranged such that their potential gradients are perpendicular to one another, and in which the alternating potentials applied across the two pairs of terminals are in quadrature with one another.
Claim 4
Dependent Claim
25 words
A display device as claimed in claim 2 in which at least one of the electrodes is transparent and is mounted on a transparent substrate.
Claim 5
Dependent Claim
87 words
A display device as claimed in claim 1 in which the voltage supply includes, for each electrode, multiplying means to which are applied a constant alternating input voltage and a variable control voltage and having its output connected to one terminal of the electrode, a constant gain amplifier to which is applied the said input voltage, and a summing amplifier having as its inputs the outputs of the multiplier and of the constant gain amplifier and having its output connected to the other terminal of the electrode.
Claim 6
Dependent Claim
33 words
A display device as claimed in claim 4 in which the control voltage is variable over the range from zero to a value numerically equal to the gain of the constant gain amplifier.
Claim 7
Dependent Claim
17 words
A display device as claimed in claim 1 in which the alternating potentials are of sinusoidal waveform.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-07-11 | 1987-01-10 | 1987-07-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-07-11 | 1991-01-10 | 1991-07-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-07-11 | 1995-01-10 | 1995-07-12 | $7700.00 | Window Closed / Lapsed |