# US 4,397,183 A · Apparatus for detecting level changes in distance

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- Number: US 4,397,183 A
- Document ID: US4397183A
- Status: Granted
- Kind: A
- Application number: 06/251,613
- Filed: 1981-04-06
- Granted: 1983-08-09
- Earliest claimed: 1981-04-06
- Assignees: Atlantic Richfield Company
- Inventors: Edmund W. Ballou; Frederick L. Voelz; Thomas A. Collins
- Web page: https://patentgrep.com/patent/US4397183A

## CPC

- G01F 23/64: of the free float type {without mechanical transmission elements}
- G01F 23/686: {using opto-electrically actuated indicating means}
- G01M 3/3245: {using a level monitoring device (G01M3/3272 takes precedence)}
- Y10S 250/90: Optical liquid level sensors
- G01F: MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01M: TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

An apparatus useful in detecting changes in distance comprises: a signal emitter capable of emitting a substantially constant signal; a signal reflector capable of reflecting at least a portion of the substantially constant signal and being moveable in a substantially straight line direction toward or away from the emitter; and a signal receiver capable of receiving the reflected signal, whereby a change in the received signal is indicative of a change in the distance between the emitter and reflector. This apparatus is particularly useful in detecting changes in the amount of liquid in a liquid storage tank.

## Claims

### Claim 1

An apparatus useful in detecting changes in the amount of liquid in a liquid storage tank comprising:
a. signal emitting means capable of emitting a substantially constant signal;
b. support means associated with said signal emitting means and acting to hold said signal emitting means substantially stationary;
c. signal reflecting means associated with support means, said signal reflecting means being located at least partially within a float means which is connected to said support means, said float means being located at least partially in said liquid, said signal reflecting means reflecting at least a portion of said substantially constant signal from said signal emitting means to produce a reflected signal, said signal reflecting means being movably secured to said support means and being moveable in a substantially straight line direction toward or away from said signal emitting means in response to changes in the amount of liquid in said storage tank; and
d. signal receiving means capable of receiving a portion of said reflected signal from said signal reflecting means, said signal receiving means being substantially stationary with respect to said signal emitting means, whereby a change in said signal received by said signal receiving means is indicative of a change in the amount of liquid in said storage tank.

### Claim 2 (depends on 1)

The apparatus of claim 1 wherein said substantially constant signal comprises light.

### Claim 3 (depends on 2)

The apparatus of claim 2 wherein said substantially constant signal comprises infra red light.

### Claim 4 (depends on 1)

The apparatus of claim 1 wherein said signal emitting means and said signal receiving means both include fiber optic transmission means.

### Claim 5 (depends on 1)

The apparatus of claim 1 which further comprises monitoring means associated with said signal receiving means and being capable of acting to monitor changes in said reflected signal received by said signal receiving means.