Abstract: In order to reproduce signals from a double-layer optical disc having two signal recording surfaces, a focus jump that the focusing of an objective lens from the one signal recording surface to the other signal recording surface is quickly achieved, is necessary. When a focus error signal (FE) from a pickup (60, 70) reaches a predetermined threshold value (Vcomp), a deceleration signal for decelerating the objective lens (42) is supplied to an actuator (47). Preferably, a deceleration pulse voltage is lowered step by step. The deceleration pulse voltage is determined in accordance with the maximum value (DFEmax) of a differential focus error signal (DFE) generated by differentiating the focus error signal (FE). Preferably, the address seeking is done simultaneously with the focus jump. The focus jump is performed in accordance with the layertolayer distance which is measured beforehand. The focus jump is performed by using a lens (143) having a controllable focal distance.

Abstract: In order to reproduce signals from a double-layer optical disc having two signal recording surfaces, a focus jump that the focusing of an objective lens from the one signal recording surface to the other signal recording surface is quickly achieved, is necessary. When a focus error signal (FE) from a pickup (60, 70) reaches a predetermined threshold value (Vcomp), a deceleration signal for decelerating the objective lens (42) is supplied to an actuator (47). Preferably, a deceleration pulse voltage is lowered step by step. The deceleration pulse voltage is determined in accordance with the maximum value (DFEmax) of a differential focus error signal (DFE) generated by differentiating the focus error signal (FE). Preferably, the address seeking is done simultaneously with the focus jump. The focus jump is performed in accordance with the layer-to-layer distance which is measured beforehand. The focus jump is performed by using a lens (143) having a controllable focal distance.

Abstract: In order to reproduce signals from a double-layer optical disc having two signal recording surfaces, a focus jump that the focusing of an objective lens from the one signal recording surface to the other signal recording surface is quickly achieved, is necessary. When a focus error signal (FE) from a pickup (60, 70) reaches a predetermined threshold value (Vcomp), a deceleration signal for decelerating the objective lens (42) is supplied to an actuator (47). Preferably, a deceleration pulse voltage is lowered step by step. The deceleration pulse voltage is determined in accordance with the maximum value (DFEmax) of a differential focus error signal (DFE) generated by differentiating the focus error signal (FE). Preferably, the address seeking is done simultaneously with the focus jump. The focus jump is performed in accordance with the layertolayer distance which is measured beforehand. The focus jump is performed by using a lens (143) having a controllable focal distance.

Abstract: A laser beam is directed from an optical head (40) while an alternating magnetic field is applied from a magnetic head (52). A reproduced signal from the optical head (40) is input to a reproduced signal detecting circuit (45) through a reproduced signal amplifying circuit (41). The detected signal (CK) of discontinuous regions provided at prescribed intervals in the groove of a magneto-optical recording medium (1) is input to an external synchronous signal generating circuit (46) and, in response, an external synchronous signal (SYN) is generated. In synchronization with the external synchronous signal (SYN), the reproduced signal detecting circuit (45) calculates a difference between the reproduced signal generated when a magnetic field for magnetic domain magnification is applied and the reproduced signal generated when a magnetic field for magnetic domain erasure is applied. The difference is detected as a reproduced signal (RF).

Abstract: A reproducing apparatus reproduces a signal recorded in a magneto-optical disk. The magneto-optical disk includes a layered structure having a recording layer, an intermediate layer and a reproducing layer. Laser light is illuminated from an optical head to the magneto-optical disk in such an intensity that no magnetic domain is transferred from the recording layer to the reproducing layer only by the laser light. In this state, alternating magnetic field is applied through a magnetic head to the magneto-optical disk, thereby concurrently causing transfer and expansion of a magnetic domain to the reproducing layer. As a result, transfer of the magnetic domain is effected with expansion.

Abstract: An optical pickup device for an AS-MO disk, a DVD and a CD includes a dual wavelength semiconductor laser with first and second oscillation devices, a polarization plane rotary unit selectively rotating a plane of polarization of a laser beam 90°, and a polarization selective diffraction grating passing a laser beam straight forward or dividing a laser beam into three beams depending upon the direction of polarization. The optical pickup device operates by the DPP tracking system where three laser beams are directed for an AS-MO disk, and by the DPD tracking system where a single laser beam is directed for a DVD or a CD. As a result, a signal can be reproduced from an AS-MO disk, a DVD, or a CD having different tracking systems.

Abstract: In order to reproduce signals from a double-layer optical disc having two signal recording surfaces, a focus jump that the focusing of an objective lens from the one signal recording surface to the other signal recording surface is quickly achieved, is necessary. When a focus error signal (FE) from a pickup (60, 70) reaches a predetermined threshold value (Vcomp), a deceleration signal for decelerating the objective lens (42) is supplied to an actuator (47). Preferably, a deceleration pulse voltage is lowered step by step. The deceleration pulse voltage is determined in accordance with the maximum value (DFEmax) of a differential focus error signal (DFE) generated by differentiating the focus error signal (FE). Preferably, the address seeking is done simultaneously with the focus jump. The focus jump is performed in accordance with the layer-to-layer distance which is measured beforehand. The focus jump is performed by using a lens (143) having a controllable focal distance.

Abstract: A reproducing apparatus reproduces a signal recorded in a magneto-optical disk. The magneto-optical disk includes a layered structure having a recording layer, an intermediate layer and a reproducing layer. Laser light is illuminated from an optical head to the magneto-optical disk in such an intensity that no magnetic domain is transferred from the recording layer to the reproducing layer only by the laser light. In this state, alternating magnetic field is applied through a magnetic head to the magneto-optical disk, thereby concurrently causing transfer and expansion of a magnetic domain to the reproducing layer. As a result, transfer of the magnetic domain is effected with expansion.

Abstract: Insulating-resin-made attachment part 13A is equipped with connection terminal 10 electrically connected to antenna element 3, and connection terminal 10 is directly connected to a prescribed circuit of a radio machine. As a mounting means to the radio machine, snap part 9 having a metal part projecting out of the sidewall of attachment part 13A is disposed.

Abstract: A magneto-optical recording medium includes a reproducing layer. When a laser beam is irradiated to the magneto-optical recording medium, a magnetic domain in a recording layer is transferred, through enlargement, to a reproducing layer increased in temperature. The magneto-optical recording medium further includes a calibration area that has a calibration magnetic domain recorded in a predetermined pattern in the recording layer. In a reproducing apparatus, a laser beam of an optical head is adjusted in output depending upon a reproduced signal obtained by reproducing the calibration magnetic domain.

Abstract: A magneto-optical recording medium which includes a reproducing layer. When a laser beam is irradiated to the magneto-optical recording medium, a magnetic domain in a recording layer is transferred, through enlargement, to a reproducing layer increased in temperature. The magneto-optical recording medium further includes a calibration area that has a calibration magnetic domain recorded in a predetermined pattern in the recording layer. In a reproducing apparatus, a laser beam of an optical head is adjusted in output depending upon a reproduced signal obtained by reproducing the calibration magnetic domain.

Abstract: A magnetic head comprises a core having a first leg, a second leg and a third leg and a coil wound on the second leg of the core. An end of the second leg is formed by a first portion formed by two inclined surfaces and a second portion formed by a flat surface. When a current is fed to the coil, a magnetic field oblique to a magnetooptical recording medium is generated from the first portion of the second leg, and a magnetic field perpendicular to the magnetooptical recording medium is generated from the second portion. Consequently, a magnetic field perpendicular to the magnetooptical recording medium can be applied to the magnetooptical recording medium for recording a signal, while a magnetooptical field having a prescribed angle with respect to the in-plane direction of the magnetooptical recording medium can be applied to the magnetooptical recording medium for reproducing a signal.

Abstract: When recording a recorded signal consisting of “01011001110” in a magnetooptical recording medium, (1,1) corresponding to a domain of 2T is converted to (1,0,1), and (0,0) is converted to (0,1,0) in the recorded signal. In other words, the first “1” of (1,1) is converted to unit bits “1,0” and the first “0” of (0,0) is converted to unit bits “0,1”. Similarly, the first “1” of (1,1,1) corresponding to a domain of 3T is converted to unit bits “1,0”, and the second “1” is converted to unit bits “1,0”. “1” or “0” of the final unit bit is not converted but recorded as such. Consequently, a signal can be correctly reproduced by extension ally transferring domains having different domain lengths from a recording layer to a reproducing layer under the same reproducing conditions.

Abstract: Insulating-resin-made attachment part 13A is equipped with connection terminal 10 electrically connected to antenna element 3, and connection terminal 10 is directly connected to a prescribed circuit of a radio machine. As a mounting means to the radio machine, snap part 9 having a metal part projecting out of the sidewall of attachment part 13A is disposed.

Abstract: The present track counter circuit is employed for a disk player of three-beam type. The track counter circuit includes a pickup having three sensors, two differential amplifiers, two zero cross detectors, an OR circuit and a counter. The first sensor is divided into two, and receives light reflected from a beam spot formed by a main beam. The outputs of the two sensor portions are applied to a first differential amplifier, the output of which is applied to a first zero cross detector. A second sensor receives light reflected from a beam spot formed by a sub beam, and a third sensor receives light reflected from a beam spot formed by another sub beam. The outputs of the second and third sensors are applied to a second differential amplifier, the output of which is applied to a second zero cross detector. The outputs of first and second zero cross detectors are applied to the OR circuit, and the counter counts crossing pulses therein in response to the OR output.