Method and apparatus for identifying defective areas on a disk surface of a disk drive based on defect density

A method for locating defective areas of a disk included as part of a hard disk drive, comprising:

• determining a number of detected defects per unit area of said disk;
• comparing said number of detected defects per unit area of said disk to a threshold amount;
• generating a flag if said number of defects per unit area of said disk is greater than said threshold amount;
• and
• receiving a first indication that a portion of said disk contains a defect, wherein said step of determining a number of defects per unit area of said disk comprises:
• in response to receiving said first indication, incrementing a value i held by a counter by a value n;
• and
• decrementing said value i held by said counter by a value s1, wherein said value i represents said number of detected defects per unit area of said disk, and wherein s1 is a rate of decay of said value i when said value i is greater than a first amount.

A method for identifying defective areas of a disk in a computer hard disk drive, comprising:

• selecting a defect density error threshold;
• assigning a value n to a defect;
• in response to receiving a signal indicating that a defect has been detected, adding said value n to a counter value i, wherein n is the amount by which i is incremented after a defect is detected, and wherein i represents a density of detected defects;
• decrementing said counter value i by an amount s for each selected portion of said disk in which a defect is not encountered, wherein s is a rate of decay of said value i;
• and
• generating a defect density error flag if said counter value i is greater than said defect density error threshold.

An apparatus for detecting defective areas of a disk included as part of a hard disk drive, comprising:

• a summing block;
• an input for receiving an indication of a defect, wherein a first value is provided to said summing block upon receipt of said indication of said defect;
• a down counter, wherein said down counter decrements a first sum received from said summing block;
• and
• a comparator, wherein a decremented sum received from said down counter is compared to a threshold value, and wherein a flag is generated if said value received from said down counter is not an acceptable value.

A method for locating defective areas of a disk included as part of a hard disk drive, comprising:

• determining a number of detected defects per unit area of said disk;
• comparing said number of detected defects per unit area of said disk to a threshold amount;
• and
• generating a flag if said number of defects per unit area of said disk is greater than said threshold amount,
• wherein said number of detected defects per unit area of said disk is determined with respect to a length of a selected track located within a selected one or more writable sectors on said disk.

A method comprising:

• providing a disk drive having a disk;
• generating a flag if a defect density in an area of said disk is greater than a selected amount, wherein said defect density is determined by:
• incrementing a counter value if a defect is detected in a selected portion of said area of said disk, and
• decrementing the counter value if a defect is not detected in a selected portion of said area of said disk.

A hard disk comprising:

• a disk;
• and
• circuitry for generating a flag if a defect density in an area of said disk is greater than a selected amount, wherein said defect density is determined by:
• incrementing a counter value if a defect is detected in a selected portion of said area of said disk, and
• decrementing the counter value if a defect is not detected in a selected portion of said area of said disk.