US3569716A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Opto-electronic liquid level sensor for maintaining a stable reference
Assignee: United States Department of the Army
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Filing: 1968-06-03
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Granted: 1971-03-09
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Expires: 1988-06-03
Abstract
Abstract An opto-electronic sensor which maintains a stable condition relative to a reference. The sensor utilizes a mercury pool contained in a steel box having relatively small dimensions. Holes in each of the four sides of the box each contain an optical glass window. Photosensitive diodes are mounted outside the windows on two adjacent sides of the box and light sources are similarly mounted on the remaining two sides so that a light source is opposite each diode. The mercury pool is adjusted to a height so as to partially block the light going from each light source to its respective diode Tilting the box along one axis or the other will increase or decrease the light reaching one or the other of the photosensitive diodes and vary the diode electrical output which can be used to control a self-leveling servo control system.
Inventors
- 👤 Virgil Dennis Lewis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 14:59
CPC Classifications
G; G01; G01F; G01F23/00; G01F23/22; G01F23/28; G01F23/284; G01F23/292; G01F23/2921; G05; G05D; G05D9/00; G05D9/12
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
319 words
An opto-electronic liquid level sensor for maintaining a stable surface with respect to a reference plane, comprising: a. liquid containing means mounted upon said surface and comprising four walls each having a transparent portion therein; b. first illuminating means mounted on the outside of the transparent portion of the first wall of said liquid containing means; c. a first photosensitive semiconductor diode mounted on the outside of the transparent portion of the second wall of said liquid containing means for producing an electrical current proportional to the light falling thereon from said first illuminating means; d. second illuminating means mounted on the outside of the transparent portion of the third wall of said liquid containing means; e. a second photosensitive semiconductor diode mounted on the outside of the transparent portion of the fourth wall of said liquid containing means for producing an electrical current proportional to the light falling thereon from said second illuminating means; f. an opaque liquid contained within said liquid containing means to block a portion of the light from said first and second illuminating means which passes through said liquid containing means so that the portion of light being blocked from said first illuminating means is proportional to the deviation of said surface from a stable condition in the level direction and the portion of light being blocked from said second illuminating means is proportional to the deviation of said surface from a stable condition in the cross-level direction; g. first and second negative bias circuits for nulling out said electrical currents from said first and second diodes, respectively when said surface is in a stable condition with respect to said reference plane whereby a bidirectional null condition is established for said level and cross-level directions; and h. control means to utilize the output signals of said first and second diodes for maintaining said surface in a stable condition with respect to said reference plane.
Claim 2
Dependent Claim
319 words
An opto-electronic liquid level sensor for maintaining a stable surface with respect to a reference plane, comprising: a. liquid containing means mounted upon said surface and comprising four walls each having a transparent portion therein; b. first illuminating means mounted on the outside of the transparent portion of the first wall of said liquid containing means; c. a first photosensitive semiconductor diode mounted on the outside of the transparent portion of the second wall of said liquid containing means for producing an electrical current proportional to the light falling thereon from said first illuminating means; d. second illuminating means mounted on the outside of the transparent portion of the third wall of said liquid containing means; e. a second photosensitive semiconductor diode mounted on the outside of the transparent portion of the fourth wall of said liquid containing means for producing an electrical current proportional to the light falling thereon from said second illuminating means; f. an opaque liquid contained within said liquid containing means to block a portion of the light from said first and second illuminating means which passes through said liquid containing means so that the portion of light being blocked from said first illuminating means is proportional to the deviation of said surface from a stable condition in the level direction and the portion of light being blocked from said second illuminating means is proportional to the deviation of said surface from a stable condition in the cross-level direction; g. first and second negative bias circuits for nulling out said electrical currents from said first and second diodes, respectively when said surface is in a stable condition with respect to said reference plane whereby a bidirectional null condition is established for said level and cross-level directions; and h. control means to utilize the output signals of said first and second diodes for maintaining said surface in a stable condition with respect to said reference plane.
Claim 3
Dependent Claim
143 words
The invention according to claim 1 wherein said control means comprises: a. first and second drive motors connected to said surface; b. a first servo control circuit to receive the output signal of said first diode for producing a control signal for said first drive motor that is proportional to the deviation of said first diode output signal from said null condition so that first drive motor will align said surface in a stable condition with respect to the level direction; and c. a second servo control circuit to receive the output signal of said second diode for producing a control signal for said second drive motor that is proportional to the deviation of said second diode output signal from said null condition so that said first drive motor will align said surface in a stable condition with respect to the cross-level direction.
Claim 4
Dependent Claim
21 words
The invention according to claim 2 wherein said first and second illuminating means are adjustable to provide varying intensities of light.
Claim 5
Dependent Claim
26 words
The invention according to claim 3 wherein the surface area of said first and second photosensitive diodes is proportional to the operating range of said sensor.
Claim 6
Dependent Claim
12 words
The invention according to claim 4 wherein said opaque liquid is mercury.
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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) | 1974-03-08 | 1974-09-07 | 1975-03-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-03-08 | 1978-09-07 | 1979-03-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-03-08 | 1982-09-07 | 1983-03-09 | $7700.00 | Window Closed / Lapsed |