| 摘要 |
PURPOSE:To obtain a highly reliable optical disk device which is capable of performing a stable recording and erasing jobs in a simple constitution, by increasing or decreasing the output power of an erasion beam gradually before and after an erased area. CONSTITUTION:A reproduction signal 31 is inputted to an address detecting circuit 32 to detect an address and outputs the detection signal 33 of fixed width. An erasing gate circuit 34 receives the input of the signal 33 and the clock from a clock generating circuit 35 for the output of an erasing gate signal 24. The clock is also inputted to a frequency dividing circuit 36 as well and divided to be supplied to a counter 37. These counted data are inputted to switch circuits 39 and 40 via a D/A converter 38. While the signals 24 and 33 are also inputted to the counter 37. Then the circuit 37 counts up the value with H of the signal 33, stops at the leading the signal 24 and counts down the value at the trailing respectively. The output of the converter 38 is supplied to both circuits 39 and 40 together with the output power setting signals 45 and 46 of light sources 1 and 2. Then either one of both outputs of circuits 39 and 40 is selected by the signal 24 and the sources 1 and 2 are turned on by driving circuits 41 and 42. Thus the erasion power is gradually increased and decreased before and after erasion. |
