Temperature compensated hall sensor for testing magnetic recording heads
AssigneeSeagate Technology LLC
InventorDavid M. Gray
Life of this patent
Estimating the term…
Abstract
A head testing apparatus is provided for testing a magnetic data recording head. The apparatus includes a test volume adapted to receive the magnetic data recording head and a magnetic field source positioned to generate a magnetic field within the test volume. A Hall sensor is positioned relative to the test volume and has bias current input terminals, voltage output terminals, an operating temperature and an impedance between the bias current input terminals, which varies with the operating temperature. A bias current source is electrically coupled to the bias current input terminals and is adapted to provide a bias current, which is modulated based on the impedance of the Hall sensor.
Claims11
A head testing apparatus for testing a magnetic data recording head, the apparatus comprising:
- a test volume adapted to receive the magnetic data storage head under test;
- a magnetic field source positioned to generate a magnetic field within the test volume;
- a Hall sensor positioned relative to the test volume and having bias current input terminals, voltage output terminals, an operating temperature and an impedance between the bias current input terminals, which varies with the operating temperature;
- a first bias current source electrically coupled to the bias current input terminals and adapted to provide a first bias current to the bias current input terminals, which is modulated based on the impedance of the Hall sensor
- a source of a reference voltage that is representative of the impedance of the Hall sensor at a nominal temperature;
- a voltage comparator circuit having a first comparison input coupled to receive a voltage developed across the bias current input terminals of the Hall sensor, a second comparison input coupled to receive the reference voltage, and a comparison output;
- and
- a current modulator having an input coupled to the comparison output and a control output coupled to a current control input of the first bias current source.
A method of compensating a voltage output of a Hall sensor for changes in the temperature of the Hall sensor, the method comprising:
- (a) applying a first bias current to bias current inputs of the Hall sensor;
- (b) measuring a representation of an impedance of the Hall sensor, wherein the impedance of the Hall sensor varies with the temperature of the Hall sensor;
- (c) modulating the first bias current as a function of the representation of the impedance of the Hall sensor measured in step (b);
- (d) positioning the Hall sensor relative to a test volume of a magnetic head testing apparatus;
- (e) positioning a magnetic data storage head within the test volume;
- (f) generating a magnetic field within the test volume with a magnetic field source;
- and
- (g) measuring the magnetic field based on the voltage output of the Hall sensor while modulating the first bias current in step (c) to compensate the voltage output for changes in the temperature of the Hall sensor.
A temperature compensated Hall sensor circuit comprising:
- a Hall sensor comprising bias current input terminals, voltage output terminals, an operating temperature and an impedance between the bias current input terminals, which varies with the operating temperature;
- and
- means for applying a bias current to the bias current inputs of the Hall sensor and modulating the bias current as a function of a comparison of a representation of the impedance of the Hall sensor and a representation of a reference impedance to reduce effects of the operating temperature of the Hall sensor at the voltage output terminals of the Hall sensor.
A head testing apparatus for testing a magnetic data recording head, the apparatus comprising:
- a test volume adapted to receive the magnetic data storage head under test;
- a magnetic field source positioned to generate a magnetic field within the test volume;
- a Hall sensor positioned relative to the test volume and having bias current input terminals, voltage output terminals, an operating temperature and an impedance between the bias current input terminals, which varies with the operating temperature;
- a first bias current source electrically coupled to the bias current input terminals and adapted to provide a first bias current to the bias current input terminals, which is modulated based on the impedance of the Hall sensor;
- and
- a programmed computer which is coupled to the first bias current source and the Hall sensor and is programmed to:
- (a) apply a control signal to the first bias current source such that the first bias current has a first current level;
- (b) measure the impedance of the Hall sensor;
- (c) compare the impedance of the Hall sensor with a reference impedance to produce a comparison output;
- and
- (d) adjust the control signal applied to the first bias current source as a function of the comparison output such that the first bias current has a second current level, which is different than the first current level.
Dependencies are inferred from the claim text.