Measurement apparatus having non-contact electrical coupling to components on a moving surface

Claim 2

A meaSurement system comprising an impedance comparison network mounted on a first member, a first resistor which varies as a function of a condition to be measured mounted on a second member, said members being mounted for relative motion therebetween, first AC coupling means providing non-contacting electrical coupling of the first resistor into the comparison network, a second adjustable resistor, second AC coupling means connected to the second resistor and providing electrical coupling into the comparison network, first signal means connected to the comparison network to provide a control signal responsive to relative magnitudes of the first and second resistors, control means responsive to the control signal to adjust the magnitude of said second resistor to maintain a predetermined ratio magnitudes between the first and second resistors, and separate circuit means connected to the second resistor to provide an output signal which is a function of the magnitude of the second resistor whereby the output signal varies as a function of the condition to be measured.

Claim 3

The system of claim 1 wherein the first AC coupling means comprises a rotary transformer having a first winding connected to the first resistor and a second winding connected to the comparison network and wherein the first winding and first resistor are mounted for movement relative to the comparison network.

Claim 4

The system of claim 2 in combination with a rotatably mounted roll, means mounting said first resistor and first winding to rotate with the roll, and wherein the first resistor varies as a function of the roll temperature.

Claim 5

The system of claim 3 including heater means for the roll, a heater controller, and means coupling the output signal to the controller, said controller regulating said heater as a function of the output signal.

Claim 6

The system of claim 1 wherein the separate circuit means providing an output signal includes a DC source connected to the second resistor, and DC amplifier means responsive to the magnitude of the second resistor.

Claim 7

The system of claim 5 and an AC shunt path including a DC blocking capacitor connected across said second resistor.

Claim 8

The system of claim 6 wherein the first resistor is a platinum thermometer and the AC shunt path is of such magnitude to cause a slightly greater relative magnitude adjustment in the second resistor relative to a magnitude change in the first resistor due to a temperature change, so that the magnitude of the second resistor is substantially proportional to temperature.

Claim 9

The system of claim 1 wherein the control means includes a light source connected to the output of said first signal means and the second resistor is a photosensitive resistor responsive to said light source.

Claim 10

The system of claim 8 wherein the first signal means includes an AC peak detector connected to the comparison network and a DC amplifier responsive to the peak detector and connected to the light source to adjust the magnitude of the second resistor in response to signals from the comparison network.

Claim 11

A circuit for delivering an output to indicate the magnitude of a variable condition from a transducer mounted on an object moving relative to means mounting a major portion of the circuit, said transducer comprising a first condition responsive resistor, a first transformer winding, said first resistor being connected in series with the first transformer winding, said first resistor and first transformer winding being mounted on said object that has relative motion to said circuit mounting means, said major portion of said circuit mounted on said mounting means including an impedance comparison network having input excitation terminals and output signal terminals, said network including a second transformer winding inductively coupled to said first transformer winding, and a third transformer winding connected in said impedance comparison network for impedance comparison with said second transformer winding, a fourth tranSformer winding inductively coupled to said third transformer winding, a second adjustable resistor in series circuit with said second transformer winding, control means to provide adjustment of the resistance of said second resistor, signal conditioning means connected to said output terminals responsive to changes in the ratio of impedance between said second transformer winding and said third transformer winding, and coupled to said control means to change the resistance of said second resistor to maintain a predetermined relationship of impedance between the second and third transformer windings, and separate second circuit means connected to said second resistor including sensing means to sense changes in said second resistor.

Claim 12

A circuit for delivering an output to indicate the magnitude of a variable condition from a transducer mounted on an object moving relative to means mounting a major portion of the circuit, said transducer comprising a first condition responsive resistor, a first transformer winding, said first resistor being connected in series with the first transformer winding, said first resistor and first transformer winding being mounted on said object that has relative motion to said circuit mounting means, said major portion of said circuit mounted on said mounting means including an impedance comparison network having input excitation terminals and output signal terminals, said network including a second transformer winding inductively coupled to said first transformer winding, and a third transformer winding connected in said impedance comparison network for impedance comparison with said second transformer winding, a fourth tranSformer winding inductively coupled to said third transformer winding, a second adjustable resistor in series circuit with said second transformer winding, control means to provide adjustment of the resistance of said second resistor, signal conditioning means connected to said output terminals responsive to changes in the ratio of impedance between said second transformer winding and said third transformer winding, and coupled to said control means to change the resistance of said second resistor to maintain a predetermined relationship of impedance between the second and third transformer windings, and separate second circuit means connected to said second resistor including sensing means to sense changes in said second resistor.

Claim 13

The combination as specified in claim 10 wherein said signal conditioning means comprises an amplifier having input terminals sensitive to changes in signal at said output terminals of said impedance comparison network, said amplifier having an output to change the value of said second resistance means.

Claim 14

The combination as specified in claim 10 wherein said sensing means includes a second amplifier, said second amplifier delivering an output proportional to the change in resistance of said second resistor.