US3683196A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Differential fluid level detector
Assignee: Texas Instruments Inc
•
Filing: 1970-11-27
•
Granted: 1972-08-08
•
Expires: 1990-11-27
Abstract
Abstract A differential fluid level detector is disclosed for sensing the presence of a fluid medium at first and second preselected levels. The detector includes a light emitter, a longitudinally extending light transmitting body of a predetermined length in excess of the difference between the first and second preselected levels in optical communication with the light emitter for transmitting emitted light along a longitudinal light emission path, a light refracting means in communication with the light emitting means through the light transmitting body and at least one light sensor. The light refracting means includes first and second light refracting body portions which are respectively disposed at longitudinally spaced positions along the light transmitting body corresponding to the first and second preselected levels and each including a light refracting body portion bounded at least in part by a surface portion at an oblique angle with respect to the longitudinal light emission path. The respective surface portions define first and second external reflective interfaces adapted to communicate with the fluid to effect transmission of the emitted light into the fluid when each respective interface is in communication with the fluid and to effect internal reflection of the light when each respective interface is not in communication with the fluid along a predetermined light reflection path through the light transmitting body. The light sensor is disposed in optical communication with the predetermined light reflection path.
Inventors
- 👤 Robert E Obenhaus
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 16:29
CPC Classifications
G; G01; G01F; G01F23/00; G01F23/22; G01F23/28; G01F23/284; G01F23/292; G01F23/2921; G01F23/2922; G01F23/2925; G01F23/2927
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
319 words
A differential fluid level detector for sensing the presence of a fluid at first and second preselected levels comprising a light emitter, a single longitudinally extending light transmitting body of a predetermined length in excess of the difference between said first and second preselected levels in optical communication with said light emitter and adapted to transmit the emitted light along a longitudinal light emission path therethrough, light refracting means in communication with said light emitting means through said light transmitting body, said light refracting means including a first and a second light refracting body each bounded at least in part by a surface portion at an oblique angle with respect to the longitudinal light emission path, said first light refracting body defining one end of said light transmitting body and being adapted to sense fluid at said first preselected level, said second light refracting body being longitudinally spaced from said first light refracting body and being defined by an inwardly extending circumferential groove which substantially completely circumscribes a portion of said light transmitting body and being adapted to sense fluid at said second preselected level, said respective surface portions defining first and second external reflective interfaces positioned at locations along said light transmitting body corresponding to said first and second preselected levels and adapted to communicate with the fluid to effect transmission of the emitted light into the fluid when each respective interface is in communication with the fluid and to effect internal reflection of the light when each respective interface is not in communication with the fluid along a predetermined light reflection path through the light transmitting body, and light sensing means having an electrical property which varies in response to the incidence of light thereon disposed in optical communication with said predetermined light reflection path for sensing the presence of reflected light as an indication of the absence of fluid at the first and second preselected levels.
Claim 2
Dependent Claim
319 words
A differential fluid level detector for sensing the presence of a fluid at first and second preselected levels comprising a light emitter, a single longitudinally extending light transmitting body of a predetermined length in excess of the difference between said first and second preselected levels in optical communication with said light emitter and adapted to transmit the emitted light along a longitudinal light emission path therethrough, light refracting means in communication with said light emitting means through said light transmitting body, said light refracting means including a first and a second light refracting body each bounded at least in part by a surface portion at an oblique angle with respect to the longitudinal light emission path, said first light refracting body defining one end of said light transmitting body and being adapted to sense fluid at said first preselected level, said second light refracting body being longitudinally spaced from said first light refracting body and being defined by an inwardly extending circumferential groove which substantially completely circumscribes a portion of said light transmitting body and being adapted to sense fluid at said second preselected level, said respective surface portions defining first and second external reflective interfaces positioned at locations along said light transmitting body corresponding to said first and second preselected levels and adapted to communicate with the fluid to effect transmission of the emitted light into the fluid when each respective interface is in communication with the fluid and to effect internal reflection of the light when each respective interface is not in communication with the fluid along a predetermined light reflection path through the light transmitting body, and light sensing means having an electrical property which varies in response to the incidence of light thereon disposed in optical communication with said predetermined light reflection path for sensing the presence of reflected light as an indication of the absence of fluid at the first and second preselected levels.
Claim 3
Dependent Claim
110 words
A detector in accordance with claim 1 wherein said second light refracting body is in optical communication with a portion of the longitudinal light emission path and said first light refracting body is in optical communication with the remainder of the longitudinal light emission path to permit a portion of the emitted light to be internally reflected along a first portion of said predetermined light reflection path by said second body and the remainder of the emitted light to be internally reflected along a second portion of said predetermined light reflection path by said first body in the absence of fluid in communication with said first and second body portions.
Claim 4
Dependent Claim
69 words
A detector in accordance with claim 2 wherein said light emitter and said light sensor are disposed in mutually spaced relationship at a common end of said light transmitting body, said first light refracting body is at an opposite end of said light transmitting bodY, and said second light refracting body is longitudinally positioned intermediate said common end of said light transmitting body and said first light refracting body.
Claim 5
Dependent Claim
56 words
A detector in accordance with claim 3 wherein another light sensor is disposed in aligned spaced facing relationship with respect to said second external reflective interface and in optical communication with said first portion of said predetermined light reflection path for sensing the absence of fluid at the level associated with said second external reflective interface.
Claim 6
Dependent Claim
62 words
A detector in accordance with claim 3 wherein said first light refracting body portion comprises a prismatic body having a predetermined geometric configuration adapted to effect internal reflection of light transmitted onto said first external reflective interface from said light emission path along said second portion of said predetermined light reflection path at an angle generally normal to said light emission path.
Claim 7
Dependent Claim
62 words
A detector in accordance with claim 5 wherein said light sensor has an electrical resistance which varies in response to light incident thereon and has a relatively high resistance value in the absence of incident light and a relatively lower resistance value in response to incident light thereon, said lower resistance value decreasing in response to the intensity of the incident light.
Claim 8
Dependent Claim
65 words
A detector in accordance with claim 6 wherein said light sensor comprises a photoelectric cell and a selectively energizable voltage responsive means is coupled to said photoelectric cell for sensing the variations in resistance thereof and providing an output signal in response to a sensed decrease in the resistance of said photoelectric cell as an indication of a fluctuation in the fluid level being detected.
Claim 9
Dependent Claim
86 words
A detector in accordance with claim 7 wherein a voltage divider is provided including a resistor having a preselected resistance value which is less than the high resistance value of said photoelectric cell in the absence of incident light and having a junction defined intermediate said photoelectric cell and said resistor, said voltage responsive means being coupled to said junction for providing the output signal in response to variations in the voltage level at said junction due to variations in the resistance of said photoelectric cell.
Claim 10
Dependent Claim
153 words
A detector in accordance with claim 5 wherein said light transmitting body comprises a generally cylindrical body of a predetermined light transparent medium, and said first light refracting body portion comprises a generally conically shaped prismatic body having its base arranged in mating light transmitting contact with said opposite end of said light transmitting body and having its vertex oriented in a direction facing the fluid to be detected, one portion of the surface of revolution of said conically shaped prismatic body defining said first external reflective interface and another portion of the surface of revolution being in aligned, spaced, facing relationship with said first external reflective interface and defining a third external reflective interface adapted to internally reflect light from said second portion of said predetermined light reflection path at an angle generally normal to said second predetermined light reflection path along a third predetermined light reflection path toward said light sensor.
Claim 11
Dependent Claim
148 words
A detector in accordance with claim 9 wherein said first portion of said predetermined light reflection path is generally normal to the path of the emitted light and a fourth external reflective interface is disposed in transversely aligned relationship with said second external reflective interface and in optical communication therewith along said first portion of said predetermined light reflection path and spaced from said second external reflective interface by a portion of said light transmitting body, said fourth external reflective interface being adapted to internally reflect incident reflected light from said first portion of said predeTermined light reflection path along a fourth portion of said predetermined light reflection path in a direction generally normal to said first portion of said predetermined light reflection path and parallel to said light emission path toward said light sensor when said fourth external reflective interface is not in communication with the fluid.
Claim 12
Dependent Claim
131 words
A detector in accordance with claim 10 wherein said second and fourth external light reflective interfaces are respectively defined by a generally bevel-shaped circumferential notch generally circumscribing and extending inwardly from the outer wall of said cylindrical light transmitting body for a predetermined distance, the inward extend of said notch terminating within the light emission path and being adapted to internally reflect a portion of the emitted light toward an opposed portion of said notch while permitting unimpeded passage of the remainder of the emitted light, said opposed notch portion terminating at a point spaced from said third portion of said predetermined light reflection path so as to avoid interference therewith and being adapted to reflect light along said fourth portion of said predetermined light reflection path toward said light sensor.
Claim 13
Dependent Claim
141 words
A detector in accordance with claim 11 wherein said light sensor comprises a photoelectric cell having a resistance which varies in response to the incidence of light thereon, the resistance of said photoelectric cell being relatively low in the absence of incident light and decreasing in a manner systematically related to the intensity of incident light thereon, wherein a voltage divider is provided including a resistor having a preselected resistance value which is less than the high resistance mode resistance level of said photo-electric cell and having a junction defined intermediate said photoelectric cell and said resistor, and a selectively energizable voltage responsive means coupled to said junction for sensing variations in the voltage level established at said junction as a result of variations in the resistance level of said photoelectric cell due to fluctuations in the fluid level being detected.
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) | 1975-08-08 | 1976-02-07 | 1976-08-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-08-08 | 1980-02-07 | 1980-08-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-08-08 | 1984-02-07 | 1984-08-08 | $7700.00 | Window Closed / Lapsed |