Head evaluating method and device, and information storage apparatus

A head evaluating device for a head comprising a read element, a recording element, a recording coil through which a recording electric current is supplied upon recording by the read element, and a heater configured to change a projection amount of the read element and recording element with respect to a medium by thermal expansion caused by electric heating, the head evaluating device comprising:

• a heater power controller configured to conduct electricity thorough the heater;
• a reproducing and recording controller configured to reproduce data from the medium or to record data on the medium, using the head;
• and
• a projection-amount-upon-recording computing module configured to compute a projection amount of the read element and recording element with respect to the medium due to the recording electric current supplied through the recording coil upon recording;
• wherein the projection-amount-upon-recording computing module is configured to:
• stop the conduction of electricity through the heater after causing the heater power controller to conduct electricity through the heater with a predetermined electric power in order to project the read element and recording element toward the medium,
• cause the reproducing and recording controller to record data in a first sector on the medium after stopping the conduction of electricity and to record data in a second sector away from the first sector by a predetermined number of at least one sector, and reproduce the data recorded in the first sector and second sector in order to compute a reproducing characteristic of the first sector and a reproducing characteristic of the second sector, and
• compute the predetermined electric power for the heater at which the reproducing characteristic of the first sector becomes substantially equal to the reproducing characteristic of the second sector, and compute the projection amount of the read element and recording element with respect to the medium due to the recording electric current supplied through the recording coil upon recording, based on the computed electric power.

An information storage apparatus comprising a head comprising a read element, a recording element, a recording coil through which a recording electric current is supplied upon recording by the read element, and a heater configured to change a projection amount of the read element and recording element by thermal expansion caused by electric heating, the head evaluating device comprising:

• a heater power controller configured to conduct electricity thorough the heater;
• a reproducing and recording controller configured to reproduce data from a medium or to record data on the medium, using the head;
• and
• a projection-amount-upon-recording computing module configured to compute a projection amount of the read element and recording element with respect to the medium due to the recording electric current supplied through the recording coil upon recording;
• wherein the projection-amount-upon-recording computing module is configured to:
• stop the conduction of electricity through the heater after causing the heater power controller to conduct electricity through the heater with a predetermined electric power in order to project the read element and recording element toward the medium,
• cause the reproducing and recording controller to record data in a first sector on the medium after stopping the conduction of electricity and to record data in a second sector away from the first sector by a predetermined number of at least one sector, and reproduce the data recorded in the first sector and second sector in order to compute a reproducing characteristic of the first sector and a reproducing characteristic of the second sector, and
• compute the predetermined electric power for the heater at which the reproducing characteristic of the first sector becomes substantially equal to the reproducing characteristic of the second sector, and compute the projection amount of the read element and recording element with respect to the medium due to the recording electric current supplied through the recording coil upon recording, based on the obtained electric power.