Abstract Apparatus for providing, at a remote location, an indication of the temperature of a rotating body, such as the rotor of a centrifuge, comprising a closed loop feed-back circuit including a voltage controlled oscillator positioned remote from the rotor and a frequency sensitive bridge circuit mounted on the rotor. The bridge circuit includes a thermistor such that the balance frequency thereof is a function of the temperature of the rotor. The output of the voltage controlled oscillator is transmitted to the rotor where it excites the bridge circuit which generates an output signal whose amplitude is a function of the difference between the frequency of the oscillator and the balance frequency of the bridge circuit. The output signal from the bridge circuit is transmitted back to the remote location where it is applied, together with the output of the oscillator, to a phase sensitive detector which serves as an error detector to adjust the frequency of the voltage controlled oscillator to null the output of the bridge circuit. The output of the voltage controlled oscillator which is transmitted to the rotor is also used to energize a self-contained power supply thereby providing power for the rotor-mounted components. In addition, the output of the voltage controlled oscillator is modulated between two amplitude levels before transmission to the rotor-mounted components. When the oscillator output is high and the power supply on the rotor is drawing current, the detector is short-circuited. When the oscillator output is low and the power supply is discharging and not drawing current, the phase sensitive detector is operative.
Apparatus for providing at a remote location an indication of the temperature of a body comprising: generating means at said remote location for generating a first signal of selectively variable frequency having at least first and second amplitude components; means electrically connected to said generating means for transmitting said first signal to said body; receiving means on said body for receiving said first signal; temperature responsive bridge circuit means on said body, having a null balance output frequency which varies as a function of the temperature of said body, electrically connected with said receiving means for producing in response to the first amplitude components of said first signal a second signal which is a function of the frequency difference between said first signal and the null balance output frequency; power supply means on said body electrically connected with said receiving means for producing only in response to the second amplitude components of said first signal energizing signals for electrical circuits on said body; and detecting means associated with said bridge circuit means for detecting in response to said second signal the temperature of said body.
Claim 2
Dependent Claim
185 words
Apparatus for providing at a remote location an indication of the temperature of a body comprising: generating means at said remote location for generating a first signal of selectively variable frequency having at least first and second amplitude components; means electrically connected to said generating means for transmitting said first signal to said body; receiving means on said body for receiving said first signal; temperature responsive bridge circuit means on said body, having a null balance output frequency which varies as a function of the temperature of said body, electrically connected with said receiving means for producing in response to the first amplitude components of said first signal a second signal which is a function of the frequency difference between said first signal and the null balance output frequency; power supply means on said body electrically connected with said receiving means for producing only in response to the second amplitude components of said first signal energizing signals for electrical circuits on said body; and detecting means associated with said bridge circuit means for detecting in response to said second signal the temperature of said body.
Claim 3
Dependent Claim
78 words
Apparatus according to claim 1 wherein said detecting means includes first antenna means on said body for transmitting said second signal; second antenna means at said remote station for receiving said second signal; and frequency adjusting means connected between said receiving antenna means and said generating means for varying the frequency of said generating means to null said second signals so that the frequency of said first signal at said null condition represents the temperature of said body.
Claim 4
Dependent Claim
38 words
Apparatus according to claim 2 wherein said bridge circuit means comprises an impedance bridge having a thermistor connected in circuit therewith, with said thermistor being positioned in heat receiving relationship with said body to sense the temperature thereof.
Claim 5
Dependent Claim
42 words
Apparatus according to claim 3 wherein said first signal has at least high and low amplitude components, with said bridge circuit means being responsive to said low amplitude components and said power supply means being responsive only to said high amplitude components.
Claim 6
Dependent Claim
53 words
Apparatus according to claim 4 wherein said power supply means includes at least one capacitor adapted to be charged only by high amplitude components of said first signal so that the bridge circuit means receives an undistorted waveform of said first signal during intervals when only said low amplitude components are present therein.