Sony Precision Technology Inc.

Other

Yasuo Nekado

Masaaki Kusumi

Shigeru Ishimoto

Mitsuru Ohno

Ken Onoe

Michio Okano

Akihiro Iwazaki

Tatsuhiro Tomari

Shinichi Inagawa

Shinji Ohkuma

Koji Matsubara

A sensor coil is provided on a core which forms a magnetic circuit for driving a linear motor, and the core is excited by electrifying the sensor coil at a high frequency. The high-frequency excitation is carried out in such a manner that the sensor coil is not magnetically saturated, and an eddy current is generated in the core. The impedance of the sensor coil is detected in this state and the quantity of a magnetic flux generated in the core constituting the magnetic circuit is detected on the basis of the impedance. Thus, the influence on the magnetic circuit itself is reduced and higher accuracy, miniaturization and lower power consumption are realized.

Magnetic flux measuring device

A position transducer capable of accurately detecting an n-bit code by a small number of ABS detectors when there is provided one ABS track. In an ABS head, the ABS detectors to are disposed for a distance &lgr; between the first ABS detector and (n&plus;m)th ABS detector to satisfy a requirement (n&minus;1)&lgr;&plus;2&dgr;<&lgr; and a distance &lgr; between two successive ones of the ABS detectors to satisfy a requirement 2&dgr;<&lgr; <&lgr;&minus;2&dgr;, so that at least one ABS detector is opposite to a stable area T in each of micro-areas at successive bits.

Position transducer

Position detection apparatus

There is provided a position transducer ( ) capable of accurately detecting an n-bit code by n ABS detectors from one ABS track. When an INC value is under j or over k, signal output from each of the ABS detectors is binarized based on a threshold h and also based on a threshold l. First, an ABS value decider ( ) decides that a bit is &ldquo;H&rdquo; when it has been judged as being &ldquo;H&rdquo; on the basis of both the thresholds and a bit is &ldquo;L&rdquo; when it is has been judged as being &ldquo;L&rdquo; on the basis of both the thresholds. When the INC value is under j, a lower bit has the same code as that of the deiced bit. So, the ABS value decider ( ) decides that the lower bit is &ldquo;H&rdquo; or &ldquo;L&rdquo;. On the other hand, when the INC value is over k, an upper bit has the same code as the decided code. Thus, the ABS value decider ( ) decides that the upper bit is &ldquo;H&rdquo; or &ldquo;L&rdquo;. The ABS value decider ( ) decides a yet-to-decide bit to be &ldquo;L&rdquo; when a bit adjacent to the bit is &ldquo;H&rdquo;, and &ldquo;H&rdquo; when the adjacent bit is &ldquo;L&rdquo;.

Two sensors are provided on a clutch core. Sensor coils are driven at a high frequency by a high-frequency driving circuit. As the sensors sense a magnetic flux of a magnetic circuit including the clutch core and an armature, the impedance of the sensor coils changes. In accordance with the outputs from the sensor coils at this point, an impedance detecting circuit detects the impedance of the sensor coils. Then, an impedance combining circuit combines the impedance of the sensor coils. On the basis of the combined impedance, a current control circuit controls a current supplied to an exciting coil. Thus, the attracting force of the armature to the core excited by the exciting coil is controlled.

Electromagnetic clutch

In a position transducer having detection coils and auxiliary coils and are driven in phase with the detection coils and and are lap-wound on the ends of the detection coils to substantially increase the winding density at the ends of the detection coils and thereby reducing the magnetic field non-linearity at the coil ends.

Position detector with magnetic core and detection and auxiliary coils

A position transducer including a scale and magnetic sensor system consisting of a first sensor unit and second sensor unit disposed in different positions in a direction (Z-direction) perpendicular to a moving direction (X-direction) of the magnetic sensor relative to the scale. The first and second sensor units are driven in phase with each other with a high frequency signal, and a difference between outputs of these two sensor units is determined in order to detect a relative position of the magnetic sensor to the scale.

Position detector utilizing two magnetic field sensors and a scale

A position transducer includes a bias circuit that drives and controls first and second bias coils. The bias circuit monitors the value of a voltage produced in a second sensor coil and drives and controls the first and second bias coils such that the value of the voltage produced in the second sensor coil is always equal to a desired voltage value.

Position detector utilizing magnetic sensors and a bias magnetic field generator

A position detecting apparatus including a magnetic scale and a magnetic sensor for detecting a magnetic field generated by the magnetic sensor. The magnetic field extending in a magnetism-sensing direction perpendicular to a first direction in which the magnetic sensor moves relative to the magnetic scale and a second direction in which the magnetic sensor is spaced from the magnetic scale. The positional relationship between the magnetic scale and the magnetic sensor is detected from the magnetic field detected by the magnetic sensor in the magnetism-sensing direction.

Position detecting apparatus utilizing a magnetic scale and sensor

A magnetic metal sensor having a high response speed and which can detect small-sized metal pieces and can elongate the separation from the metal pieces. A magnetic metal sensor,has a core,defining a substantially U-shaped open magnetic path and coils,of the same polarity mounted on the core,A uniform magnetic field along the direction of magnetic sensitivity is applied by a magnet,across the coils,If magnetic metal approaches to a open magnetic path portion of the core,of the magnetic metal sensor,the magnetic reluctance of the magnetic circuit formed by the core and air is changed, as a result of which the impedance of the cores,is changed. The magnetic metal sensor,detects the possible presence of magnetic metal or its displacement based on impedance changes of the paired coils

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Kanagawa, Japan

Yasuo Nekado