US4670654A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Thermal image sensor with means for converting a phase image into an insity modulated image
Assignee: STC PLC
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Filing: 1985-08-07
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Granted: 1987-06-02
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Expires: 2005-08-07
Abstract
Abstract A thermal image is created in a thermostatically controlled liquid crystal cell (4) containing a two-frequency nematic or cholesteric (3). This is addressed with an alternating potential whose frequency can be swept through the cross-over frequency. By appropriate choice of frequency within this range the thermal image is converted to a phase image which in its turn is converted to a contrast image in conventional manner.
Inventors
- 👤 Peter W. Ross
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 23:24
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/132; G01; G01J; G01J5/00; G01J5/48
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
99 words
A thermal image sensor, which sensor includes a thermostatically controlled liquid crystal cell containing a two-frequency liquid crystal layer sandwiched between a pair of internal transparent sheet electrodes; a power supply connected across the electrodes, the output frequency of which power supply is controllable through the cross-over frequency of the liquid crystal layer; means for creating a thermal image in said layer, which image, in the presence of the power supplied by the power supply, is such as to produce a phase image in said layer; and optical means for converting said phase image into an intensity modulated image.
Claim 2
Dependent Claim
99 words
A thermal image sensor, which sensor includes a thermostatically controlled liquid crystal cell containing a two-frequency liquid crystal layer sandwiched between a pair of internal transparent sheet electrodes; a power supply connected across the electrodes, the output frequency of which power supply is controllable through the cross-over frequency of the liquid crystal layer; means for creating a thermal image in said layer, which image, in the presence of the power supplied by the power supply, is such as to produce a phase image in said layer; and optical means for converting said phase image into an intensity modulated image.
Claim 3
Dependent Claim
29 words
A sensor as claimed in claim 1, wherein both major surfaces of the liquid crystal layer are bounded by surfaces promoting parallel homogeneous alignment of the liquid crystal molecules.
Claim 4
Dependent Claim
37 words
A sensor as claimed in claim 2, wherein in the absence of any applied field the twist in the liquid crystal layer is substantially an angle selected from the group comprising 0°, 90°, 180°, 225°, and 270°.
Claim 5
Dependent Claim
57 words
A sensor as claimed in claim 1, wherein one major surface of the liquid crystal is bounded by a surface promoting parallel homeogeneous alignment of liquid crystal molecules in contact therewith while the other major surfaces of the liquid crystal layer is bounded by a surface promoting homeotropic alignment of the liquid crystal molecules in contact therewith.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-06-01 | 1990-12-01 | 1991-06-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-06-01 | 1994-12-01 | 1995-06-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-06-01 | 1998-12-01 | 1999-06-02 | $7700.00 | Window Closed / Lapsed |