SU871106A1 - Method of galvanomagnetic transducer thermal stabilization - Google Patents

Description

I

The invention relates to instrumentation and can be used to create accurate magnetometers with galvano-magnetic sensors.

A known method of thermally stabilizing a Hall sensor is based on measuring its temperature by changing the voltage between the current terminals of the sensor and using the measurement result to maintain the temperature of the sensor constant 111.

The disadvantages of the method:

- selection of the power of the measuring circuit into the temperature measurement circuit

- influence on the accuracy of the temperature measurement circuit of the temperature variation of the resistance of the connecting wires, comparable to the resistance of the Hall sensor.

Closest to the proposed method of thermal stabilization of galvanomagnetic sensors J.

In this method of thermal stabilization of the sensor, the sensor parameter (control current) is affected by a magnetic field of a given magnitude, as a result of which the voltage is applied to the combination frequency of the control current and the applied magnetic field (modulation voltage), according to the value of which keep the temperature of the sensor at 10 sto

Claims (2)

To create the Hall voltage, it is necessary to have an additional magnetic field created by a special coil, the presence of which negates one of the main advantages of Hall sensors being the ability to measure in small volumes and narrow gaps. In addition, the coil created by the additional magnetic field is exposed to the surrounding ferromagnetic media, as a result of which the value of the additional magnetic FIELD changes, and consequently, the accuracy of the thermal stabilization scheme is reduced. In order to increase the accuracy, in order to thermally stabilize galvanomagnetic sensors in a way in which a voltage is passed from the output voltage to the combinative frequency of a rim control current and a modulation voltage, an additional current is passed through the sensor, the resistance value of the sensor with the modulation frequency is changed, and the amplitude of the voltage with the combination frequency is judged on the magnitude of the subsequent change in the value of the additional current. The drawing shows a diagram of a device that implements the proposed method. As a galvanomagnetic sensor, a magnetoresistor 1 with pins 2, 3 and a controlled attenuator 4 connected to a generator 5 connected to one of the arms of a bridge circuit formed by resistors 6–8 were used. To one diagonal connected current generator 9 | The phase-sensitive selective tra 10 and the recording device 11 of the main measuring circuit are connected to another. Selective amplifier 12 is connected to one of the inputs of the comparison device 13 via a linear detector 14, and a resistor 15 is connected to another input of the comparison device 13. A DC amplifier 16 connected through the resistor 17 is connected to the output of the comparison device The method is carried out as follows. The bridge circuit, in one of the arms of which the magnetoresistor 1 is turned on, is alternately unbalanced by changing the resistance of the controlled attenuator 4, the value of which is changed by OTR echo ro + LekvDO-eqro-D e where Oj is the initial resistance of the magnetic resistor 1J D is the increment of equivalent resistance as a result. modulations with a frequency of 52 ... As a result of this process, the zero signal of the magnetoresistor 1, determined by the initial resistance Pp, is modulated with a frequency SJ. therefore, the frequency of the zero signal of the magnetoresistor is different from the frequency (S) of the voltage of the magnetoresistor effect arising under the influence of the measured magnetic field. Due to the fact that the main measuring circuit, consisting of a phase-sensitive selective path 10 tuned to the frequency W, and the recording device 11, is connected to another bridge diagonal, the output voltage of the bridge carrying information about the measured magnetic field is filtered out, and Output voltage with frequency yzJ +, carrying information about the temperature of the magnetoresistor 1. is filtered out, amplified by a selective amplifier 12 tuned to one of the frequencies (L) + yi-, An on-line detector 14, the output of which is connected to one of the inputs of the comparison device 13, on the other input of which the setpoint voltage from the resistor 15 arrives, which determines the set temperature of the resistor I. In the case of a deviation of the temperature from its set value, the output of the comparison device 13 appears output voltage, which determines the magnitude of the output current of the dc amplifier 16, which maintains a given sensor temperature. The resistor 17 is designed to isolate the circuits of the generators 5 and 9 from the output circuit of the DC amplifier 16. The resistance of the galvanomagnetic sensor can also be modulated by applying a light flux or electric field to it. As a result of the implementation of the proposed method, the measurement accuracy is improved due to an increase in the thermal stabilization accuracy. In addition, it is possible to make measurements near ferromagnetic bodies and in narrow gaps without reducing the accuracy of thermal stabilization. Claims The method of thermal stabilization of galvanomagnetic sensors, in which from an output voltage a voltage is applied with a combination frequency of the control current and a modulation voltage, characterized in that, in order to increase the accuracy. 5, an additional current is passed through the sensor, the value of the resistance of the sensor with the modulation frequency is varied, and the magnitude of the voltage with the combination Frequency determines the value of the subsequent change of the additional current value. Sources of information taken into account in the examination 1. Avtorskoe svdedelstvo USSR 469106, cl. G 01 K 33/06, 1974. 2. USSR author's certificate for application No. 2565722 / 18-21, cl. G 01 -R 33/06, 1978 (prototype).