Abstract @ A disk unit includes a control unit (17,18,) for controlling the stop position of a positioning electric motor (11) and positioning a magnetic head (9) on a predetermined data track on a magnetic disk, and positioning error adjustment unit (19) for supplying analog signals to the control unit, wherein the analog signals are related to the positioning error detected by the magnetic head. An exciting current which goes high during a time interval T1 and goes low during a time interval T2 during a period T is caused to flow in a first exciting coil of the motor while an exciting current which goes low during the same time interval T1 and goes high during the same time interval T2 is caused to flow in another exciting coil adjacent to the first coil and the duration of the time intervals T1 and T2 with respect to the period T is adjusted by the control unit, as a function of the magnitude of the aforementioned analog signal. Thus, the two currents have adjustable duty cycles which are the inverse of one another. This permits fine adjustment of the stopping position of the motor.
A disk unit comprising an electric motor (11) for positioning a head (9) in alignment with a data track (7), and motor control means including means (17,19) for correcting head position errors, characterised in that for adjustment of the head position, the motor control means provides motor excitation currents pulsed with a duty cycle dependent on a detected head position error.
Claim 2
Dependent Claim
61 words
A disk unit comprising an electric motor (11) for positioning a head (9) in alignment with a data track (7), and motor control means including means (17,19) for correcting head position errors, characterised in that for adjustment of the head position, the motor control means provides motor excitation currents pulsed with a duty cycle dependent on a detected head position error.
Claim 3
Dependent Claim
81 words
A disk unit as claimed in claim 1 in which the motor has a plurality of exciting coils (A-D) characterised in that the control means applies a first pulsed excitation current to a first coil and a second pulsed excitation current to a second coil whereby the excited coils together define the position of the motor and therefore of the head, and the second excitation current has a pulse waveform which is the inverse of that of the first excitation current.
Claim 4
Dependent Claim
166 words
A disk unit according to claim 1 comprising control means (17) for controlling the stop position of the positioning electric motor (11) and positioning error adjustment means (19) for supplying signals to stop position adjustment means (17A), said signals being related to the positioning error detected by the head, characterised in that as a function of the magnitude of said signals from said positioning adjustment means, an exciting current which goes high for a time interval Tl and goes low for a time interval T2 during a period T is caused to flow in one of the exciting coils (A-D) of said positioning electric motor, while an exciting current which goes low during the same time interval T) and goes high during the same time interval T2 is caused to flow in another exciting coil adjacent to said one of the exciting coils, said stop position adjustment means being operative for adjusting the duration of said time intervals Tl, T2 with respect to said period T.
Claim 5
Dependent Claim
70 words
The disk unit according to claim 3 characterised in that said stop position adjustment means comprises means (30) for calculating the sense and the magnitude of the positioning error as a function of said signals and outputting a corresponding signal S2 and means (31) for determining the duty ratio of the stepping motor driving input pulse on the basis of said output signal S2 and outputting a corresponding signal S3.
Claim 6
Dependent Claim
19 words
The disk unit according to any preceding claim characterised in that the positioning electric motor is a stepping motor.
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