US3846775A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electro-optical display apparatus for signalling warning of predetermined condition ambient compensated
Assignee: Texas Instruments Inc
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Filing: 1972-10-06
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Granted: 1974-11-05
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Expires: 1992-10-06
Abstract
Abstract A display device signals a warning for the existence of a condition, such as low fuel in a motor vehicle and employs an element in which certain optical properties of a liquid crystal composition change when a threshold voltage is applied across it in response to a controlling sensor. The sensor is located in a fluid reservoir and exhibits a first resistance level while being cooled by the fluid and a second resistance level when out of contact with the fluid. The sensor is electrically coupled with the composition so that the voltage gradient impressed across the composition is dependent upon the resistance level of the sensor. Improved contrast and ambient temperature compensation is achieved in certain of the embodiments by mounting the liquid crystal composition in heat transfer relation with an electrical resistance filament.
Inventors
- 👤 H Epstein
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 08:01
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/13; G02F1/133; G02F1/1333; G02F1/133382; G01; G01F; G01F23/00; G01F23/22; G01F23/28; G01F23/284; G01F23/292; G01F23/2921; G02F1/1313
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
224 words
Automotive warning display apparatus comprising: a sensor having a steeply sloped positive temperature coefficient of electrical resistance; a housing having an open end; an electrical resistance lamp element mounted within the housing having a portion adjacent the open end thereof; a display element received in and closing the open end of the housing and in heat transfer relation with the electrical resistance lamp element including: a first optically transmissive substrate having an optically transmissive and electrically conductive coating on a face thereof, a second substrate having an electrically conductive coating on a face thereof, the substrates being positioned such that the coatings are adjacent and substantially parallely spaced, a liquid crystal composition occupying the space between the coatings on the substrates, the composition having a threshold voltage level at which an optical characteristic of the composition is changed; and voltage impressing means for impressing a voltage gradient between the coatings, the sensor being electrically coupled to the means for impressing a voltage gradient so that current is conducted through the sensor, the sensor normally operating in one of two temperature ranges, the resistance level of the sensor controlling the magnitude of the voltage gradient, the voltage impressing means including means to electrically energize the electrical resistance lamp element, heat from the lamp element being transferred to the display element to provide ambient temperature compensation.
Claim 2
Dependent Claim
224 words
Automotive warning display apparatus comprising: a sensor having a steeply sloped positive temperature coefficient of electrical resistance; a housing having an open end; an electrical resistance lamp element mounted within the housing having a portion adjacent the open end thereof; a display element received in and closing the open end of the housing and in heat transfer relation with the electrical resistance lamp element including: a first optically transmissive substrate having an optically transmissive and electrically conductive coating on a face thereof, a second substrate having an electrically conductive coating on a face thereof, the substrates being positioned such that the coatings are adjacent and substantially parallely spaced, a liquid crystal composition occupying the space between the coatings on the substrates, the composition having a threshold voltage level at which an optical characteristic of the composition is changed; and voltage impressing means for impressing a voltage gradient between the coatings, the sensor being electrically coupled to the means for impressing a voltage gradient so that current is conducted through the sensor, the sensor normally operating in one of two temperature ranges, the resistance level of the sensor controlling the magnitude of the voltage gradient, the voltage impressing means including means to electrically energize the electrical resistance lamp element, heat from the lamp element being transferred to the display element to provide ambient temperature compensation.
Claim 3
Dependent Claim
61 words
Apparatus according to claim 1 in which the liquid crystal is nematic and the optical characteristic which changes upon application of threshold voltage level is a light transmitting characteristic whereby light passing therethrough is relatively unimpeded when the voltage level is below the threshold and is dynamically scattered when the voltage level is at least as high as the threshold level.
Claim 4
Dependent Claim
46 words
Apparatus according to claim 2 in which the sensor comprises a thermistor formed of material having a positive temperature coefficient of resistivity, the sensor having a first low resistance state at temperatures below an anomaly and a second high resistance state at temperatures above the anomaly.
Claim 5
Dependent Claim
17 words
Apparatus according to claim 2 in which one of the substrates is etched with a desired symbol.
Claim 6
Dependent Claim
40 words
Apparatus according to claim 3 in which the sensor is electrically coupled in series with the display element, and a resistor is coupled across the display element to permit current to flow to the sensor from the voltage impressing means.
Claim 7
Dependent Claim
16 words
Apparatus according to claim 3 in which the sensor is electrically coupled across the display element.
Claim 8
Dependent Claim
42 words
Apparatus according to claim 3 further including a fluid reservoir, the sensor mounted in the reservoir such that it is completely immersed in the fluid when the reservoir is filled but is exposed when the fluid level falls beyond a predetermined limit.
Claim 9
Dependent Claim
25 words
Apparatus according to claim 2 in which one of the conductive layers of the display element is formed in the shape of a desired symbol.
Claim 10
Dependent Claim
157 words
A display unit comprising: a housing having an open end; an electrical resistance lamp element mounted within the housing having a portion adjacent the open end thereof; an optically transmissive lens received in and closing the open end of the housing and in heat transfer relation with the electrical resistance lamp element, the lens formed of a first and second parallely spaced optically transmissive substrates, the substrates each having an optically transmissive and electrically conductive coating on a face thereof, a liquid crystal composition occupying the space between the substrates, the composition having a threshold voltage level at which an optical characteristic of the composition is changed; and voltage impressing means connectable to the coatings and to the electrical resistance lamp element for impressing a voltage gradient between the coatings and for permitting current to flow through the electrical resistance lamp element, heat from the lamp element being transferred to the lens to provide ambient temperature compensation.
Claim 11
Dependent Claim
157 words
A display unit comprising: a housing having an open end; an electrical resistance lamp element mounted within the housing having a portion adjacent the open end thereof; an optically transmissive lens received in and closing the open end of the housing and in heat transfer relation with the electrical resistance lamp element, the lens formed of a first and second parallely spaced optically transmissive substrates, the substrates each having an optically transmissive and electrically conductive coating on a face thereof, a liquid crystal composition occupying the space between the substrates, the composition having a threshold voltage level at which an optical characteristic of the composition is changed; and voltage impressing means connectable to the coatings and to the electrical resistance lamp element for impressing a voltage gradient between the coatings and for permitting current to flow through the electrical resistance lamp element, heat from the lamp element being transferred to the lens to provide ambient temperature compensation.
Claim 12
Dependent Claim
19 words
A display unit according to claim 9 in which the liquid crystal composition is a temperature sensitive nematic composition.
Claim 13
Dependent Claim
25 words
Apparatus according to claim 9 further including a sensor electrically coupled to the lens coatings, the sensor comprising a thermistor whose resistance varies with temperature.
Claim 14
Dependent Claim
44 words
Apparatus according to claim 11 in which the thermistor is formed of material having a positive temperature coefficient of resistivity, the thermistor having a first low resistance state at temperatures below an anomaly and a second high resistance state at temperatures above the anomaly.
Claim 15
Dependent Claim
20 words
Apparatus according to claim 11 in which the thermistor is formed of material having a negative temperature coefficient of resistivity.
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) | 1977-11-04 | 1978-05-06 | 1978-11-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-11-04 | 1982-05-06 | 1982-11-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-11-04 | 1986-05-06 | 1986-11-05 | $7700.00 | Window Closed / Lapsed |