Claims
- 1. A fluid level detector with associated drop counter for use with a transparent container which comprises:
- a first photoelectric transducer associated with said container having its light path aimed through said container for operating in a first state when said light path is refracted by a fluid in said container and operating in a second state when said light path is unrefracted by a fluid;
- a second photoelectric transducer associated with said container having its light path aimed through said container to generate a signal for providing a normalized input to said first photoelectric transducer corresponding to no fluid in said container;
- means connected to said second photoelectric transducer to count interruptions of the light path of said second photoelectric transducer; and
- an alarm associated with said second photoelectric transducer to indicate an empty container when said second state is equivalent to a no fluid condition as established by said normalized input.
- 2. A fluid level detector as recited in claim 1 wherein said second photoelectric transducer is positioned to establish an unrefracted light path through said container above the level of the fluid therein.
- 3. A fluid level detector as recited in claim 2 wherein said container is a drip chamber which further comprises an input orifice shaped as a drop former to create drops of the fluid entering said container.
- 4. A fluid level detector as recited in claim 3 wherein said second photoelectric transducer is positioned with its light path intersecting the path of drops falling from said drop former.
- 5. A fluid level detector as recited in claim 4 wherein said container is cylindrically shaped.
- 6. A fluid level detector as recited in claim 5 wherein the light path of said second photoelectric transducer is aimed toward and substantially perpendicular to the longitudinal axis of said container.
- 7. A fluid detector with associated drop counter which comprises:
- a first photoelectric means;
- a second photoelectric means coupled to said first photoelectric means for generating a reference signal for input to said first photoelectric means, said reference signal corresponding to the condition when a fluid does not affect the light path of said second photoelectric means;
- means associated with said first photoelectric means for generating a variable control signal, said control signal being in a first state when fluid substantially affects the light path of said first photoelectric means in a second state when fluid does not substantially affect the light path of said first photoelectric means;
- means connected to said second photoelectric transducer to count modulated interruptions of said reference signal; and
- an alarm means associated said first photoelectric means to indicate the absence of fluid when said control signal is a calibrated equivalent of said reference signal.
- 8. A fluid detector as cited in claim 7 further comprising:
- a transparent container; and
- means for holding a portion of said container in the light path of said first photoelectric means.
- 9. A fluid detector as cited in claim 8 wherein said holding means holds a portion of said container in the light path of said second photoelectric means.
- 10. A fluid detector as cited in claim 9 wherein said first and second photoelectric means are operable with invisible light.
- 11. A fluid level detector as recited in claim 10 wherein said second photoelectric means is positioned to establish an unrefracted light path through said container above the level of the fluid therein.
- 12. A fluid level detector as recited in claim 11 wherein said container is a drip chamber which further comprises an input orifice shaped as a drop former to create drops of the fluid entering said container.
- 13. A fluid level detector as recited in claim 12 wherein said second photoelectric means is positioned with its light path intersecting the path of drops falling from said drop former.
- 14. A fluid level detector as recited in claim 13 wherein said container is cylindrically shaped.
- 15. A fluid level detector as recited in claim 14 wherein the light path of said second photoelectric means is aimed toward and substantially perpendicular to the longitudinal axis of said container.
- 16. A method for counting the drops of fluid entering a transparent fluid container and detecting the emptying of the container which comprises the steps of:
- A. mounting a first photoelectric means on said container with the light path of said first photoelectric means passing through said container above the fluid level in said container in a position to be interrupted and modulated by said fluid drops for generating a reference signal having a component equivalent to a no-fluid-in-container condition;
- B. attaching means to said first photoelectric means for counting modulations of said reference signal;
- C. mounting a second photoelectric means on said container to generate a control signal, said control signal being in a first state when fluid substantially affects the light path of said second photoelectric means and in a second state when fluid does not substantially affect the light path of said second photoelectric means;
- D. comparing said control signal to said reference signal; and
- E. alarming to indicate an empty container condition when said control signal is a calibrated equivalent to a no fluid condition as established by said reference signal.
BACKGROUND OF THE INVENTION
This is a continuation-in-part of U.S. application Ser. No. 834,698 filed on Feb. 27, 1986, now U.S. Pat. No. 4,665,391.
US Referenced Citations (8)
Foreign Referenced Citations (4)
Number |
Date |
Country |
2406640 |
Aug 1975 |
DEX |
2437798 |
Feb 1976 |
DEX |
2855651 |
Jun 1980 |
DEX |
1417111 |
Dec 1975 |
GBX |
Non-Patent Literature Citations (1)
Entry |
"Circuit Optimizes Optical-Switch Biasing", by Wayne M. Spani, EDN Sep. 20, 1979. |
Continuations (1)
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Number |
Date |
Country |
Parent |
834698 |
Feb 1986 |
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