Abstract: There is disclosed an optical pickup device including: a blue semiconductor laser which emits a first laser light having a wavelength of 450 nm or less to record on or reproduce from an extra-high density optical disc; a red semiconductor laser which emits a second laser light having a wavelength longer than that of the first laser light to record on or reproduce from a DVD having a low recording density; an objective lens; and an aberration correction element. The objective lens is designed for the extra-high density optical disc, and has a numerical aperture (NA) of 0.75 or more. The aberration correction element passes the first laser light as such and thereafter allows the light to be incident upon the objective lens, whereas the element limits an aperture with respect to the second laser light and diffracts the second laser light so as to correct an aberration with respect to the DVD and thereafter allows the light to be incident upon the objective lens.

Abstract: The optical sampling system realizes the optical sampling by detecting the interference effect which is a linear correlation between the signal lights and the optical pulses, so that it suffices for both the signal lights and the optical pulses to have relatively low intensities, and the reception sensitivity is high. Also, the pulse width of the optical pulses and the amount of delay given to the optical pulses are the only factors that limit the time resolution, so that it is possible to provide the optical sampling system with excellent time resolution and power consumption properties, and it is possible for the optical sampling system to monitor not only the intensity of the signal lights but also the frequency modulation component as well.

Abstract: There is disclosed an objective lens for an optical disk, comprising a bi-aspherical single lens having a numerical aperture of 0.7 or more, wherein a center thickness of the lens is larger than a focal distance.

Abstract: An telephone answering apparatus connected to a facsimile apparatus. A controller transmits a response message stored in a memory to the line, and starts recording an incoming message inputted from the line into the memory. In a case where a tone detector detects a tone signal, the controller releases the line and records a switching message stored in the memory instead of the incoming message. This prevents wasting incoming message storing capacity due to recording a tone signal and erroneous operation of the facsimile apparatus caused by reproducing a recorded tone signal.

Abstract: An optical receiver for receiving tile optical signals with high speed modulation at a high sensitivity. In this optical receiver, a local beam synchronized with a carrier of the optical signal is generated, and multi-frequency local beam components obtained from the local beam are spatially resolved to obtain spatially resolved beams with mutually different frequencies. Then, the optical signal and the obtained spatially resolved beams are entered into the photo-detector element array simultaneously to obtain an interference fringe pattern. The received optical signal is then reconstructed by Fourier analyzing the interference fringe pattern obtained by the photo-detector element array.

Abstract: A motor control circuit includes a driver which amplifies a drive signal and outputs a drive current to a coil of a motor ; a detection circuit which detects a drive waveform of the drive current and outputs a detection pulse representing a rotating condition of the motor as a detection signal ; and a drive signal generating circuit which generates in response to the detection pulse a trapezoidal wave having a linear inclination at front and rear parts thereof as the drive signal.

Abstract: A motor control apparatus for rotating a motor smoothly. A sine wave form which is an ideal wave form of a signal is stored, and the motor is driven by a signal having the ideal wave form obtained by correcting the period and the phase of the stored sine wave form. A comparator receives a detection signal which indicates the rotating state of the motor through an A/D converter, and obtains the correction values of the current period and phase. A wave form setting means corrects the set period and phase, generates a sine wave having the corrected period and phase on the basis of the sine wave data stored in a sine wave data region, and outputs a driving signal having the sine wave form through a D/A converter.

Abstract: A motor control circuit and a motor drive system using the same, in which a first transistor between the collector-emitter of which a first current in response to a drive signal for driving a motor is flown and a second transistor the base of which is connected to the base of the first transistor and between the collector-emitter of which a second current in response to the first current is flown are included, and the second current or a current dependent upon the second current is outputted to the coil of the motor as a motor drive current and the second transistor is turned to the saturation condition when the voltage at the coil rises more than a predetermined value, comprising a detection circuit of the saturation condition which is connected to the base of the second transistor and generates a detection signal in response to a voltage variation of the base of the second transistor when the second transistor operates under the saturation condition; and a feed-back circuit which decreases the second curren

Abstract: A magnetron constructed by locating a pair of permanent magnets in a vacuum container which is an anode cylinder (i.e. shell) of magnetic material and has upper and lower covers of magnetic material to form a magnetic circuit. A high frequency resonator is formed by attaching anode vanes directly to the internal wall of the anode cylinder and providing a film of highly conductive material on the internal wall of the anode cylinder between the anode vanes. Terminals for the supply of power to a cathode disposed between the permanent magnets pass through a hole in at least one of the permanent magnets and one of the covers of the magnetic material. An antenna, or probe, extends out of a hole in the side wall of the anode cylinder, and heat radiative fins are attached directly to the external wall of the anode cylinder.