Patent ID: 7414928

Claim:
A method for determining a sub-beam add signal (SBAD) value applied in an optical disc drive when N data packets are written onto a disc during N read status and N write status, wherein the N read status include a first to an N th read status, the N write status include a first to an N th write status, the N data packets include a first to an N th data packet, the optical disc drive reads the optical disc at the i th read status and writes the i th data packet onto the optical disc at the i th write status where i ranges from 1 to N, the optical disc drive has a predetermined write SBAD gain, and the method comprises: reading the optical disc and obtaining a first read SBAD value at the first read status; writing the first data packet onto the optical disc at the first write status and obtaining a first write SBAD value according to the predetermined write SBAD gain; obtaining a first SBAD multiple according to the first write SBAD value and the first read SBAD value; changing the predetermined write SBAD gain into a first write SBAD gain according to the first SBAD multiple; reading the optical disc and obtaining a j th read SBAD value at the j th read status, wherein j ranges from 2 to N-1; writing the j th data packet onto the optical disc at the j th write status and adjusting the level of a j th write SBAD value according to the (j−1) th write SBAD gain; obtaining a j th SBAD multiple according to the j th write SBAD value and the j th read SBAD value; changing the (j−1) th write SBAD gain into a j th write SBAD gain according to the j th SBAD multiple; reading the optical disc and obtaining a (j+1) th read SBAD value at the (j+1) th status;and writing the (j+1) th data packet onto the optical disc at the (j+1) th write status and adjusting the level of a (j+1) th write SBAD value according to the j th write SBAD gain.