Patent ID: 7406012

Claim:
A semiconductor laser driving device comprising: a semiconductor laser for emitting light irradiated on an optical recording medium; a photodetecting element for receiving a part of the light emitted from the semiconductor laser and converting the part of light into an electric signal corresponding to a light amount; a laser driving circuit for inputting a driving signal into the semiconductor laser such that an average value of the electric signal coincides with a target value; a high-frequency superimposing circuit for superimposing a high-frequency signal over the driving signal; and a high-frequency superimposing control section for controlling an amplitude of the high-frequency signal, wherein the high-frequency superimposing control section is operable to control the amplitude of the high-frequency signal such that a peak-to-average ratio that is a ratio of a peak value of the electric signal with respect to the average value of the electric signal does not increase above a first reference value, and wherein the high-frequency superimposing control section is operable to control the amplitude of the high-frequency signal such that the amplitude decreases to lower the peak-to-average ratio as the average value increases, if the average value is less than a threshold value, and the amplitude increases to raise the peak-to-average ratio as the average value increases, if the average value is larger than the threshold value.