Abstract: A head-switching circuit for switching a first head operating on a first recording medium to a second head operating on a second recording medium so as to read out data written on a recording medium according to a staggered servo mechanism, includes a selector for selecting one of the recording media, a classifier 20, 30, 31, 32 and 33 for classifying the skew time of a recording medium selected by the selector and another recording medium selected by the selector, a sync signal generator 40, 41, 42, 50, 51, 60, 61, 62, 70, 71, 72 and 80 enabled by the output signal of the classifier and for generating a sync signal when the skew time is identical with a predetermined time, thereby generating a sync signal precisely during head-switching in staggered servo mechanism.

Abstract: A servo sector forming method for fast detection and corresponding track address correcting method. The track address correcting method for a disk driving/recording apparatus uses as a recording medium a disk comprised of a plurality of track groups. A plurality of tracks are incorporated in each group, each having a data sector and a servo sector with a gray code field separated into a higH.sub.-- gray code field and a low-gray code field, a gap field for supplying the synchronization point of time and a parity bit field in which a group change information is recorded. The gray code read from the higH.sub.-- gray code field and low-gray code field is decoded during a track detection to detect a read address. A correction value for correcting a track address according to the track detection direction is added to the read address to detect the track address. Therefore, track detection time can be maintained in a high-capacity hard disk drive, irrespective of extension of a gray code field.

Abstract: A servo address mark (SAM) detection compensating circuit in a disk recording apparatus includes a servo address mark (SAM) detector that receives an end of sector (ENDS) signal indicating that the end of a prescribed recording region has been reached, generates a synchronizing signal (SYNC) when the servo address mark (SAM) is detected during a window enable interval, and generates an error detection signal when the servo address mark (SAM) is not detected during the window enable interval. A first storage device generates a first count value representative of a first time interval extending from when detection of the servo address mark (SAM) is expected to when a desired recording region is to be sampled, and a second storage device generates a second count value in response to the error detection signal. The second count value represents a second time interval extending from when detection of the servo address mark (SAM) is expected to when the window enable interval ends.

Abstract: A head-switching circuit for switching from a first head operating on a first recording medium to a second head operating on a second recording medium so as to read out data written on a recording medium according to a staggered servo mechanism, includes a selector for selecting one of the recording media, a classifier (20, 30, 31, 32, 33 and 34) for classifying the skew time of a recording medium selected by the selector and another recording medium selected by the selector, a sync signal generator (40, 41, 42, 50, 51), (60, 61, 62, 70, 71, 72 and 80) enabled by the output signal of the classifier for generating a sync signal when the skew time to is identical with a predetermined time, thereby generate a sync signal precisely during head-switching in staggered servo mechanism.

Abstract: Disclosed is a circuit for detecting an unrecorded portion of a recording medium, which has a window counting portion (10) for receiving an input signal, for recognizing if the input signal comes from an unrecorded portion of the recording medium and for counting a predetermined time to generate a window signal. The circuit also has a sync signal generator (20) which is enabled by the window signal, in which, if the number of pulses of the input signal equals or exceeds a predetermined number, the generator recognizes that the current input signal comes from a data region of the recording medium and therefore generates a sync signal. If the number of pulses of the input signal is less than the predetermined number of pulses, the generator recognizes that the current input signal is due to noise from an unrecorded region of the recording medium, and therefore does not generate the sync signal.