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US 5,207,101 AGranted
Two-wire ultrasonic transmitter
AssigneeMagnetrol International, Incorporated
InventorKevin M. Haynes
Life of this patent
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AssigneeMagnetrol International, Incorporated
InventorKevin M. Haynes
Estimating the term…
A two-wire ultrasonic transmitter senses level of a material and controls current of power supplied thereto to a magnitude representing sensed level The transmitter comprises a transducer mounted in proximity to a material, the level of which is being sensed. A power supply circuit receives power for operating the instrument. A drive circuit is connected to the transducer and the power supply circuit and periodically energizes the transducer to transmit an energy pulse to be reflected off of a surface of the sensed material. An amplifier circuit is connected to the transducer and develops an analog signal having a magnitude corresponding to reflected energy received by the transducer. A control circuit is operatively coupled to the drive circuit and the amplifier circuit and determines time difference between a first time when the drive circuit energizes the transducer and a second time when the analog signal is above the threshold, the time difference representing level, and energizes the amplifier circuit for a select minimum time duration commencing subsequent to energization of the transducer and terminating after receipt of a return echo pulse A current control circuit is coupled to the control circuit for controlling current received by the power supply circuit to a magnitude representing sensed level.
An instrument for sensing level of a material comprising:
A two wire ultrasonic transmitter for sensing level of a material and controlling current of power supplied thereto to a magnitude representing sensed level, comprising:
An ultrasonic transmitter for sensing level of a material and including a transducer self-test mode of operation, comprising:
Dependencies are inferred from the claim text.
No related US applications are recorded in the indexed filing history.
Drawings are temporarily unavailable. Open the PDF at USPTO
Of systems according to group G01S15/00: constructional features
Acoustic waves: measuring transit time of reflected waves
Of systems according to group G01S15/00: means for monitoring or calibrating
Receivers: extracting wanted echo signals
Term ended 6 Sep 2011 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
This invention relates to process control instruments, and more particularly, to a two-wire ultrasonic transmitter.
Process control systems require the accurate measurement of process variables. Typically, a primary element senses the value of a process variable and a transmitter develops an output having a value that varies as a function of the process variable. For example, a level transmitter includes a primary element for sensing level and a circuit for developing an electrical signal proportional to sensed level.
An electrical transmitter must be connected to an electrical power source to operate. One form of such a transmitter, known as a four-wire transmitter, includes two terminals for connection to a power source and two terminals for carrying a loop signal proportional to the process variable. This signal can be used as an input to a controller or for purposes of indication. Because the instrument is connected directly to a power source, power consumption is a less critical factor in design and use of the same.
FIG. 1 is an elevational, partial sectional view of the ultrasonic transmitter according to the invention;
FIG. 2 is an electrical schematic diagram illustrating a circuit on a power supply printed circuit board of the transmitter of FIG. 1;
FIG. 3a+b is a schematic diagram illustrating a circuit on a logic printed circuit board of the transmitter of FIG. 1;
With reference to FIG. 1, an ultrasonic through air transmitter 10 according to the invention is illustrated. The transmitter 10, as discussed more specifically below, can be operated in hazardous locations and is of the two-wire type. The transmitter 10 is operable to transmit a sound pulse directed at a surface of a material, the level of which is being sensed, and to receive a reflective sound signal. The time of flight is monitored to determine distance from the transmitter 10 to the surface. Being of the two-wire type, the transmitter 10 receives a user supplied voltage and draws a controlled amount of current based on user set control switches and the distance measured to the surface.
The transmitter 10 comprises a housing 12 including a base 14 threadably receiving a cover 16 to define an interior space 18. An O-ring 20 seals the interior space 18 from the space outside of the enclosure 12. A conduit port 22 is provided for connection to a conduit to connect the transmitter 10 to remote control or indicating equipment. A hollow pipe 24 extends downwardly from the base 14 and is closed at a distal end 26. An NPT-type connector 28 is provided for threadably connecting the pipe 24 to a vessel or tank, having a material the level of which is to be sensed.
A bracket 30 is mounted to the base 14 using two screws 32 within the space 18. Mounted to the bracket 30 are a power supply printed circuit board 34 and a logic printed circuit board 36. A multiconductor cable 38 extends from the logic printed circuit board and down through the pipe 24 to an amplifier printed circuit board (not shown) including a transducer, discussed relative to the schematic of FIG. 4.