| 摘要 |
<p>When a header on an optical disk (1) is detected by a header detector (30), a switch (51) is turned on by an output from the header detector (30), and an output from a laser beam detector (8b) is held in an integrator (54). The output level of the integrator (54) is compared with a reference value defined by a resistor (58) by a comparator (55). A transistor (57) is driven by an error output obtained by the comparison, thus driving a semiconductor laser unit (9).</p> |
