Abstract: An optical drive includes a comparator for comparing a first input signal with a second input signal to generate a first output signal at a first node; a signal source coupled to a second node, the signal source outputting a second output signal; and a switch for outputting a third output signal at a third node, the third output signal controlling a laser power of the optical drive, wherein when the switch is switched to the first node, the first output signal is transmitted to the third node and serves as the third output signal, and when the switch is switched to the second node, the second output signal is transmitted to the third node and serves as the third output signal.

Abstract: A method for automatically controlling output power of a pick-up head. When output power of a pick-up head is to be changed, a first switch is utilized to connect a first input port of a comparator circuit to a supply source, and a second switch is utilized to connect a first signal source to a driver circuit such that the driver circuit will control the output power according to a first signal. When voltage drop between the first input port and a output port of the comparator circuit stabilizes, the first switch is utilized to connect the first input port to a sensor, and the second switch is utilized to connect the output port and the driver circuit such that the driver circuit will control the output power according to a comparative signal.

Abstract: A method for automatically controlling output power of a pick-up head. When output power of a pick-up head is to be changed, a first switch is utilized to connect a first input port of a comparator circuit to a supply source, and a second switch is utilized to connect a first signal source to a driver circuit such that the driver circuit will control the output power according to a first signal. When voltage drop between the first input port and a output port of the comparator circuit stabilizes, the first switch is utilized to connect the first input port to a sensor, and the second switch is utilized to connect the output port and the driver circuit such that the driver circuit will control the output power according to a comparative signal.