| 摘要 |
A mechanical ultrasonic scanner includes a transducer element which is swingably supported in a housing, and a sensor for detecting a swinging angle of the transducer element. The sensor includes a permanent magnet swung together with the transducer element, and a magnetoresistive element fixed to the housing to be opposite to a swinging locus of the permanent magnet. The permanent magnet generates a magnetic field between the permanent magnet and the magnetoresistive element. The magnetoresistive element detects a strength of the magnetic field which changes in correspondence with a swinging angle of the magnet, so that the swinging angle of the transducer element is detected on the basis of the change in the strength of the magnetic field. Even if the housing contains a sound transmitting medium, the magnetic field generated by the sensor is not adversely affected by the sound transmitting medium. Therefore, the swinging angle of the transducer element can be accurately detected to accurately obtain a radiating/returning direction of an ultrasonic beam, thus accurately reconstructing an image. In addition, the position of the transducer element can be controlled with high precision.
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