| 摘要 |
PROBLEM TO BE SOLVED: To perform correct controls of outgoing light quantities without interrupting a reproducing operation by adjusting light quantities of light beams and adjusting the total amount of light beams from plural individual laser beam sources and adjusting outgoing light quantities based on outputs of a photodetecting means while lighting induvidual lasers in a period which does not include an information reproducing time. SOLUTION: A CPU 11 inputs a digital signal D4 being the temp. detection data of a temp. sensor 14 and compares this value with the value stored in a variable Temp. at the time a light quantity control operation is executed at a previous time. When the CPU 11 detects the temp. change of not smaller than a prescribed value, it makes only a laser beam a' emit by making driving currents I2 , I3 zero and a photodiode 7 receives a detection data signal D1 corresponding to a laser beam a' to compare it with a prescribed value. The CPU 11 performs the control of a light quantity by raising a digital signal D2 when the D1 is lower than the prescribed value and reducing a driving current when it is higher than the value. |
