Abstract: A reproduction and/or recording device for optical recording media which is compatible in respect of varying storage density, despite an interdependence between pit or domain size, and the light spot size. Use is made of a track guidance signal generation device which can be changed over according to the storage density type and is connected to a detector which can be used for recording media of varying storage density, i.e. in the form of the standardized CD, minidisk or MOD, and for optical recording media, which have a comparatively higher information storage density, or smaller track spacings and smaller dimensions of the pits or storage structures.

Abstract: A system for guidance of an optical scanning device is disclosed in which a gain factor (G factor) is responsive to a track error signal which is a function of the deflection of a scanning device. Deviation of the G factor setting from an optimum setting is automatically determined in conjunction with an open track control loop by driving a servo device (SV) to deflect an actuator from its neutral position and by evaluating a push-pull signal (PPTE). The G-factor is automatically set to an optimum value.

Abstract: A magneto optical disc system includes a disc having permanently recorded tracks overlain with magneto optical recording material. Data is recorded in the magneto optical material in tracks superimposed over the permanently recorded tracks, using the read-only data to define magneto optical tracks. The magneto optically recorded data is correlated with the prerecorded data for defining the location of data stored in the magneto-optic tracks.

Abstract: In an optical recording apparatus light is directed to and reflected from a recording medium to recover recorded information. The intensity of direct and reflected light is measured and the ratio of the measured values is used to control the intensity of the light source to maintain the intensity of reflected light substantially constant.

Abstract: A digital recorder which includes an A/D converter for converting analog signal to digital form for recording and a D/A converter for converting recovered recorded digital information to analog form, includes switch circuitry for interconnecting the D/A converter and the A/D converter in a manner to perform sample rate conversion of input digital signals to condition the recorder to record digital signals having different sample rates.

Abstract: The two sets of data stored in pits and a magneto-optical layer of an optical recording/reproducing device can be read separately by the use of two lasers. The laser which reads/records the data stored in the pits operates at a wavelength .lambda..sub.1 approximately four times the depth of the pits. The laser which reads/records the data stored in the magneto-optical layer operates at a wavelength .lambda..sub.2 approximately twice the depth of the pits. The wavelength of the laser which reads the magneto-optical layer is adjusted and interference between the two signals is avoided.

Abstract: The beam of light reflected from an optico-magnetic recorded medium is reflected by an optical pick-up onto one optical or another in accordance with the direction that the beam's plane of polarization is rotated in. A data signal is obtained from the difference in the photovoltages of the two photodetectors.

Abstract: A circuit arrangement for reversing a magnetic field, in which an oscillator has a coil connected in parallel with a capacitor. First and second diodes are connected oppositely-poled in a series circuit, which is connected in parallel with the coil and capacitor of said oscillator. A first electronic controlled switch is connected in parallel with the first diode for bypassing this diode, whereas a second electronic controlled switch is connected in parallel with the second diode for bypassing thereof. Energy is supplied to the oscillator whenever the capacitor discharges. The junction of the series connected diodes is connected to the junction of the series-connected switches.

Abstract: An improved cooling device for cooling the magnetic head (M) of a magneto-optical disc player includes a plurality of arcuate ribs (R) formed as portions of concentric circles and having centers coincident with the axis of rotation of the disc player. The reading/recording head (M) is arranged between the ribs. The rotation of the disc in the proximity of the cooling device creates airflow between the ribs and serves to cool the magnetic head.

Abstract: An optical scanning system for a compact disc having a sinusoidal data track radially meandering, at a selected frequency, about the axis of rotation of the disc includes a first laser beam for reading data from the data track. A +1 level laser beam and a -1 level laser beam respectively track the opposite edges of the data track and generate a tracking error signal. The +1 level laser beam and the -1 level laser beam are separated, with respect to the disc, by a distance equal to an odd integer multiple of one half the wavelength corresponding to the selected frequency. The +1 and -1 laser beams are not modulated by the sinusoidal data track and standard tracking circuitry can be used to track the data track.

Abstract: A circuit for reversing a magnetic field in which a bifilar coil is provided with a series of two oppositely-wound windings that are connected together at one end to form a junction. A source of current is connected in series with an inductive resistor, and this series circuit is connected at one end to the junction. At the other end of this series circuit, there is a voltage supply source. Each of the two oppositely-wound windings has its other end connected to a variable switch. The two variable switches have control inputs that are connected to two outputs from a control unit which applies a reference potential to each winding through the variable switch, so that all current from the source of current flows through each winding upon closure of the respective variable switch.

Abstract: At magneto-optical recording- and reproducing equipment is provided an electromagnet, in order to be able to remagnetize the magneto-optical layer of a magneto-optical record in dependence of Bits to be stored.In order to achieve a fast and safe reversal of the magnetic field, two series circuits consisting of a first and a second diode (D1, D2), a series circuit consisting of a third and a fourth diode (D3, D4) and a DC-voltage source (U) are connected in parallel to each other. The common terminal (A) of the first and second diode (D1, D2) are connected via a coil (L) with the common terminal (B) of the third and fourth diode (D3, D4). The second diode (D2) is bypassed by a first variable switch (S1) and the fourth diode (D4) is bypassed by a second variable switch (S2).

Abstract: A circuit arrangement for detecting and recognizing the type of optical recording medium being scanned, in which a high pass filter is connected in series with a rectifier. The high pass filter receives a data signal containing information stored in the recording medium. A low pass filter has an input which receives also the data signal. The first input of a comparator is connected to the output of the rectifier, whereas the rectifier has an input connected to the output of the high pass filter. A second input of the comparator is connected to an output of the low pass filter, and a controls processor is connected to an output of the comparator. A second comparator may be provided with a first input connected to the output of the rectifier, whereas the second input of the second comparator is connected to a reference voltage. The output of this second comparator is also connected to the controls processor which recognizes the type of recording medium being scanned from the outputs of the comparators.

Abstract: An optically-recorded medium in which a reflecting optomagnetic layer is applied to a transparent substrate layer. The recorded medium stores data magnetically and by pits. The magnetically stored data and the pit stored data are superimposed on each other, so that every spot and region on the recorded medium stores both magnetically stored data and pit stored data. The recorded medium is not divided into separate regions for magnetically stored data and pit stored data, and the magnetically stored data and pit stored data may be read out simultaneously by a single light beam.

Abstract: An optical scanning arrangement in which a laser beam is generated by a source with a monitor diode. The laser beam is focused on an optical recording medium. A summing amplifier has a first input connected to a source of a periodic signal. This source of periodic signal is also connected to a first input of a multiplier. The multiplier has an output connected to a second input of the summing amplifier. This summing amplifier has an output connected to a positioning device in the focusing circuit for the laser beam. This focusing circuit has an actual value which is supplied to a third input of the summing amplifier. The multiplier receives a laser controlling signal on a second input for the purpose of maintaining the light output of the laser beam at a constant level.

Abstract: An optical pick-up for scanning a magneto-optically recorded disk in which the disk reflects a first principal beam onto a first photodetector. This first principal beam has a plane of polarization which is rotated in one direction. The recorded disk reflects a second principal beam onto a second photodetector. This second principal beam has a plane of polarization that is rotated in another direction. A data signal is generated from the difference between output photovoltages of the first and second photodetectors. A diffraction grating splits the main beam from a light emitting source, into the principal beams and into subsidiary beams. The main beam from the light emitting source is focused on the recorded disk through the diffraction grating. Auxiliary photovoltages are generated from the auxiliary beams, and these are subtracted for generating the data signal. The output voltage of the second photodetector has noise components that are in phase and which are generated by the main beam.

Abstract: An arrangement for adjusting a radiation detector in a scanning system that scans a surface, in which the surface reflects rays emitted by a radiation source. The reflected rays are focused onto a radiation detector by at least one focusing element. The radiation detector has at least two individual detectors. A summation signal and at least one difference signal is constructed from output signals of the detectors. The radiation detector is adjusted perpendicular to the optical axis of the system by oscillating selectively one of the source of radiation, the focusing element, or the surface so that a focal point arrives in front of the radiation detector when the oscillating focusing element, oscillating source of radiation, or oscillating surface is displaced by a maximum in one direction. The focal point, on the other hand, arrives behind the radiation detector when the focusing element, source of radiation, or surface is displaced by a maximum in another direction.