Abstract: This optical read/write apparatus has first and second optical heads 2a, 2b and includes location control sections 4a, 4b which make the relative arrangement of the first and second optical heads 2a, 2b variable according to either the environmental temperature or from one medium to another. The first optical head 2a performs a write operation to record a mark on an optical storage medium 1, and the second optical head 2b reads the information that has been written by scanning the recorded mark. The apparatus further includes a nonvolatile memory which saves the relative arrangement of the first and second optical heads 2a and 2b either on an environmental temperature basis or on a medium by medium basis.

Abstract: This optical read/write apparatus has first and second optical heads 2a, 2b and includes location control sections 4a, 4b which make the relative arrangement of the first and second optical heads 2a, 2b variable according to either the environmental temperature or from one medium to another. The first optical head 2a performs a write operation to record a mark on an optical storage medium 1, and the second optical head 2b reads the information that has been written by scanning the recorded mark. The apparatus further includes a nonvolatile memory which saves the relative arrangement of the first and second optical heads 2a and 2b either on an environmental temperature basis or on a medium by medium basis.

Abstract: In an optical information reproduction apparatus having optical beam sources having at least two types of wavelengths, an object lens may be damaged by colliding with an information recording medium while driving a focus servo, which is caused by a fake signal generated due to an incompatibility of the wavelength in use with the information recording medium. To solve such a problem, in case the type of the information recording medium is unrecognizable and a focus servo is led in by using the optical beam source having the first wavelength, the focus servo is led in by using the second focus servo lead-in unit which is driven by an output of a near focus point detection unit during an operation of a second focus search unit which renders the object lens move away from the information recording medium.

Abstract: A clock extracting device of a disc reproducing apparatus includes an information read-out member for reading information signals from a disklike information recording medium; a voltage control oscillator; a phase comparator; a frequency comparator; a speed sensor for detecting the frequency of the output of the voltage control oscillator at a reference clock so as to output a speed signal; a gain command unit for designating a loop gain of a clock extracting circuit in accordance with the speed signal outputted from the speed sensor; a charge pump which discharges or draws electric current in accordance with outputs of the phase comparator and the frequency comparator and changes over an output current value in accordance with a gain command of the gain command unit; and a series circuit of a resistor and a capacitor, wherein the gain command unit issues the gain command such that the loop gain of the clock extracting circuit secures a desired operating point in accordance with a read rate of the information

Abstract: In an optical information reproduction apparatus having optical beam sources having at least two types of wavelengths, an object lens may be damaged by colliding with an information recording medium while driving a focus servo, which is caused by a fake signal generated due to an incompatibility of the wavelength in use with the information recording medium. To solve such a problem, in case the type of the information recording medium is unrecognizable and a focus servo is led in by using the optical beam source having the first wavelength, the focus servo is led in by using the second focus servo lead-in unit which is driven by an output of a near focus point detection unit during an operation of a second focus search unit which renders the object lens move away from the information recording medium.

Abstract: A clock extracting device of a disc reproducing apparatus, comprising: an information read-out member for reading information signals from a disklike information recording medium; a voltage control oscillator; a phase comparator for comparing a phase of the information signals read by the information read-out member and a phase of an output of the voltage control oscillator; a frequency comparator for comparing a frequency of the information signals read by the information read-out member and a frequency of the output of the voltage control oscillator; a speed sensor for detecting the frequency of the output of the voltage control oscillator at a reference clock so as to output a speed signal; a gain command unit for designating a loop gain of a clock extracting circuit in accordance with the speed signal outputted from the speed sensor; a charge pump which discharges or draws electric current in accordance with outputs of the phase comparator and the frequency comparator and changes over an output current va