Patent ID: 7522494
Filing Date: 2009-04-21
Classification: G11B

Abstract:
1. An apparatus for driving a light source that emits a laser beam shone on an optical disc, comprising: an electric-current-signal source unit configured to output at least three electric current signals; a drive-signal generating unit configured to combine said at least three electric current signals into a single drive signal that causes the light source to emit the laser beam having highest power among all pulses of the laser beam used for recording information on the optical disc; and an electric-current-signal adjusting unit, the apparatus being configured to drive the light source for recording and reproducing information on and from the optical disc that is a rewritable optical disc, wherein said at least three electric current signals include a first electric current signal, a second electric current signal, and a third electric current signal, the first electric current signal having a signal level smaller than a threshold current level at which the power of the laser beam as a function of an electric current supplied to the light source exhibits a steep rise from a proximity of zero power, the second electric current signal having a signal level substantially equal to a difference between a signal level corresponding to write power and a signal level corresponding to erase power, and the third electric current signal having a signal level substantially equal to a difference between a signal level corresponding to erase power and the signal level of the first electric current signal, and wherein the electric-current-signal adjusting unit is configured to adjust the first electric current signal and the second electric current signal in response to a monitor signal indicative of the power of the laser beam.