Head switching operation utilizing an automatic dummy load
AssigneeSeagate Technology LLC
InventorsRobert Matousek, Timothy T. Walker
Life of this patent
Estimating the term…
Abstract
Apparatus and method for a head switching operation utilizing an automatic dummy load in a disc drive. A preamplifier circuit sequentially selects head positions and applies corresponding bias currents. A sequence control circuit automatically diverts the path of a first bias current from a head selection circuit to a dummy load after detecting an input of a second head location value into a buffer, and before the input is complete. After a bias current value for the second head is written into the buffer, the sequence control automatically deasserts the path to the dummy load after a predetermined time interval. The second bias current is then applied to the second head.
Claims7
A method for switching from a first head to a second head in a disc drive, comprising steps of:
- (a) applying a first bias current of first magnitude to the first head;
- (b) detecting input of a multi-bit head selection value indicative of the second head to a buffer of a preamp of the disc drive and simultaneously switching the first bias current from the first head to a dummy load before completion of the input of the head selection value in the buffer;
- (c) switching from the first bias current of first magnitude to a second bias current of a second magnitude so that the second bias current is applied to the dummy load;
- and
- (d) switching from the dummy load to the second head so that the second bias current of the second magnitude is applied to the second head.
A preamplifier circuit for applying a bias current to a plurality of heads of a head/disc assembly of a disc drive, comprising:
- a head selection circuit;
- a bias current source which generates the bias current;
- an array of programmable registers, operably coupled to the head selection circuit and the bias current source, wherein a digital value stored in one of the registers causes the head selection circuit to select one of the plurality of heads and causes the bias current source to generate a bias current of selected magnitude in relation to the digital value;
- and
- a sequence control circuit which detects inputting of a particular digital value to switch from a first head to a second head and which diverts the bias current generated by the bias current source from the first head to a dummy load before completion of the inputting of the particular digital value to the respective register, the sequence control circuit subsequently connecting the bias current source to a second head upon completion of inputting another particular digital value indicative of desired magnitude of bias current to be applied to the second head.
A head/disc assembly of a disc drive, comprising:
- first and second heads supported adjacent corresponding first and second
- disc recording surfaces;
- and means for switching between the first and second heads.
Dependencies are inferred from the claim text.