TRANSDUCER POSITION CONTROL SYSTEM FOR DATA TRANSFER APPARATUS EMPLOYING DISKLIKE RECORD MEDIA

In a data storage and retrieval system employing a magnetic disk as the storage medium, a monophase encoder is coupled, typically, to an electric seek motor for optoelectronically producing an output representative of the position of a data transducer with respect to a multiplicity of concentric data tracks on the disk. Electrically connected to the monophase encoder is a triple detector circuit for deriving from the encoder output a transducer position signal representative of the transducer position on the disk, an actual transducer speed signal representative of the transducer speed relative to the disk, and a track boundary signal representative of boundaries between the data tracks on the disk. The transducer position signal and actual transducer speed signal are both fed to a seek motor control circuit, whereas the track boundary signal is fed to a controller microprocessor, which then delivers to the seek motor control circuit a requested transducer speed signal at which the transducer is to be moved across the data tracks during operation in a seek mode. In response to the incoming signals the control circuit controls the seek motor for transporting the transducer to a desired track at a desired speed and for positioning the transducer in centerline alignment with the track.