JPS6362922U - - Google Patents

Description

[Brief explanation of the drawing]

As an example of this invention, FIGS. 1A and B
are the block diagram and waveform diagram of the focus search circuit, Figure 2 is the waveform diagram of the sliding operation, Figure 3 is the focus search waveform generation circuit diagram, and Figure 4 is the waveform diagram of each part of the focus search waveform generation circuit. 5 is a block diagram of a conventional focus search circuit, and FIGS. 6A and 6B are block diagrams and waveform diagrams of another embodiment of the focus search circuit according to this invention. 1: Optical recording medium, 2: Sliding shaft, 3: Objective lens, 4: Magnet, 5: Objective lens mounting part, 6
: Half mirror, 7: Collimator lens, 8: Laser diode, 9: Cylindrical lens, 1
0: Photo detector, 11: Laser oscillation control circuit, 12: Focus error generation circuit, 13: Focus servo circuit, 14: Focus search waveform generation circuit, 15: Focus actuator driver circuit, 16: Changeover switch, 17: Microcomputer, 18: Focus actuator coil, 19: Optical pickup actuator section, 20
: Optical system unit, 21...Comparator, 22...D flip-flop, 23: Logic circuit (AND), 24
...Offset voltage.

Claims (1)

[Claims for Utility Model Registration] When writing information on an optical recording medium or optically reading information recorded on an optical recording medium, the light collected through the objective lens of the optical pickup actuator section is A photodetector that detects an optical pattern, a focus error generation circuit that converts the optical pattern obtained by this photodetector into a focus error signal, a compensation circuit that uses this output to configure a servo loop, and a focus error generation circuit that converts the optical pattern obtained by the photodetector into a focus error signal. A focus actuator driver circuit that drives the focus actuator, a focus search waveform generation circuit that generates a signal to move the focus actuator back and forth to find a position where a servo loop can be formed, and a focus error signal. In an optical disk player comprising a switch that switches from the focus search waveform generation circuit side to the focus error generation circuit side for forming a focus servo loop based on the output of the focus search waveform generation circuit, A signal is supplied to the focus actuator drive circuit via the switch to drive the focus actuator for a predetermined period of time to cause it to reciprocate and perform a pull-in operation to the focus servo loop. and means for prohibiting switching of the switch to the focus error generation circuit side even if a focus error signal is input to the focus error generation circuit during the predetermined time. A focus search circuit characterized by: