Optically coupled calibrator for transmitters
First Claim
1. Apparatus for calibrating a two wire DC transmitter of the type having a sensor which provides a time varying sensor signal representative of a parameter to be sensed, current control means for controlling, as a function of time varying signals received, total DC current in two wires which couple the transmitter to an external DC power supply and an external series connected load, the apparatus comprising:
- a calibrator having;
an oscillator means for generating a known time varying oscillator signal;
light emitting means coupled to the oscillator means for providing a time varying light signal in response to the time varying oscillator signal; and
opening means providing for passage of light from the calibrator; and
the two wire transmitter having;
light sensor means for receiving the time varying light signal from the calibrator and for providing a time varying calibration signal as a function of the time varying light signal;
selection means for selectively providing the time varying calibration signal or the time varying sensor signal to the current control means; and
adjustment means for adjusting the total DC current from the transmitter when the time varying calibration signal is selected to provide a known relationship to the known time varying oscillator signal, thereby calibrating the transmitter.
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Accused Products
Abstract
A calibrator for use in calibrating a two wire DC transmitter includes an oscillator and a light emitter which produce a time varying light signal of known frequency. No physical connection is required between the calibrator and the transmitter, other than a path for the light signal. The transmitter includes a light sensor which is responsive to the presence of the light signal and which produces a time varying calibration signal in response to the light signal. Calibration adjustment circuitry in the transmitter is used to adjust the output of the transmitter when the calibration signal is provided, thereby calibrating the transmitter.
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Citations
22 Claims
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1. Apparatus for calibrating a two wire DC transmitter of the type having a sensor which provides a time varying sensor signal representative of a parameter to be sensed, current control means for controlling, as a function of time varying signals received, total DC current in two wires which couple the transmitter to an external DC power supply and an external series connected load, the apparatus comprising:
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a calibrator having; an oscillator means for generating a known time varying oscillator signal; light emitting means coupled to the oscillator means for providing a time varying light signal in response to the time varying oscillator signal; and opening means providing for passage of light from the calibrator; and the two wire transmitter having; light sensor means for receiving the time varying light signal from the calibrator and for providing a time varying calibration signal as a function of the time varying light signal; selection means for selectively providing the time varying calibration signal or the time varying sensor signal to the current control means; and adjustment means for adjusting the total DC current from the transmitter when the time varying calibration signal is selected to provide a known relationship to the known time varying oscillator signal, thereby calibrating the transmitter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. In combination:
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a portable calibrator for use in conjunction with calibration of two wire DC transmitters comprising; a calibrator housing; oscillator means within the calibrator housing for generating a known time varying oscillator signal; light emitting means coupled to the oscillator means for providing a time varying light signal in response to the time varying oscillator signal; and opening means in the calibrator housing for permitting passage of the time varying light signal from the calibrator; a two wire transmitter having two output terminals for connection to two wires which couple the transmitter to an external DC power supply and external series connected load, the transmitter comprising; a transmitter housing; parameter sensing means for providing a time varying sensor signal representative of a parameter to be sensed; light sensor means for receiving the time varying light signal from the calibrator and for providing a time varying calibration signal as a function of the time varying light signal; selection means within the transmitter housing for selectively providing the time varying calibration signal or the time varying sensor signal; current control means connected to the output terminals of the transmitter for controlling, as a function of the time varying signal provided by the selection means, total DC current in the two wires which couple the transmitter to an external DC power supply and an external series connected load; and adjustment means for adjusting the total DC current when the time varying calibration signal is selected to provide calibration of the transmitter. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. Apparatus for calibrating a two wire transmitter of the type having a sensor which provides a time varying sensor signal representative of a parameter to be sensed, convertor means for converting time varying signals to DC signals, and current control means coupled to the convertor for controlling, as a function of the DC signals from the convertor means, the total DC current in two wires which couple the transmitter to an external DC power supply and an external series connected load, the apparatus comprising:
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a calibrator having an oscillator for generating a known time varying oscillator signal, light emitting means coupled to the oscillator for providing a time varying light signal in response to the time varying oscillator signal, and opening means for permitting passage of the light signal from the calibrator; light sensor means associated with the two wire transmitter for receiving a light signal from the calibrator and providing a time varying calibration signal as a function of the light signal; switch means associated with the transmitter for selectively coupling the time varying calibration signal to the convertor means; and adjustment means associated with the transmitter for adjusting the total DC current from the transmitter when the time varying calibration signal is coupled to the convertor means, to calibrate thereby the transmitter.
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20. A calibrator for calibrating a device of the type having a sensor which provides a time varying sensor signal representative of a parameter to be sensed, means for controlling, as a function of time varying signals received, an output signal of the device, the calibrator comprising:
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means for generating a known time varying signal; light emitting means for providing a time varying light signal in response to the known time varying signal; opening means providing for passage of light from the calibrator; and wherein the device further includes; means for receiving the time varying light signal from the calibrator and for providing a time varying calibration signal as a function of the time varying light signal; selection means for selectively providing the time varying calibration signal or a signal which is a function of the time varying sensor signal to the means for controlling an output signal; and adjustment means for adjusting the output signal of the device when the time varying calibration signal is selected to provide a known relationship to the known time varying signal, thereby calibrating the device.
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21. In combination:
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a portable calibrator for use in conjunction with calibration of transmitters comprising; a calibrator housing; means within the calibrator housing for generating a known time varying signal; light emitting means for providing a time varying light signal in response to the time varying oscillator signal; and opening means in the calibrator housing for permitting passage of the time varying light signal from the calibrator; a transmitter having output terminals for providing an output signal to a circuit including an external load, the transmitter comprising; a transmitter housing; parameter sensing means for providing a time varying sensor signal representative of a parameter to be sensed; means for receiving the time varying light signal from the calibrator and for providing a time varying calibration signal as a function of the time varying light signal; selection means for selectively providing the time varying calibration signal or the time varying sensor signal; means connected to the output terminals of the transmitter for controlling the output signal as a function of the time varying signal provided by the selection means; and adjustment means for adjusting the output signal when the time varying calibration signal is selected to provide calibration of the transmitter.
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22. Apparatus for calibrating a transmitter of the type having a sensor which provides a time varying sensor signal representative of a parameter to be sensed, converter means for converting time varying signals to DC signals, and control means coupled to the converter for controlling, as a function of the DC signals from the converter means, an output signal of the transmitter, the apparatus comprising:
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a calibrator having means for generating a known time varying signal, light emitting means coupled to the oscillator for providing a time varying light signal in response to the known time varying signal, and opening means for permitting passage of the light signal from the calibrator; means associated with the transmitter for receiving a light signal from the calibrator and providing a time varying calibration signal as a function of the light signal; switch means associated with the transmitter for selectively coupling the time varying calibration signal to the converter means; and adjustment means associated with the transmitter for adjusting the output signal of the transmitter when the time varying calibration signal is coupled to the converter means, to calibrate thereby the transmitter.
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Specification