Abstract: A dry-shaving apparatus comprising a cutter roller provided with straight shaving cutters each having an associated hair-pulling lead cutter, and a skin guide member and a shear-cutting member between which a helical hair-entrance aperture is formed.

Abstract: A playback apparatus for a recorded frequency modulated television signal includes a filter between the record carrier pick-up heads and the limiter-demodulator. The filter characteristics increase the ratio of the carrier signal frequency to the lower side band frequencies in response to a drop in carrier amplitude.

Abstract: An optical disc player comprises a read objective on a carriage which is translated to and fro with the aid of a drive unit with an electric motor by cooperation of a drive pinion and a gear rack, so that the read objective travels between a minimum diameter and a maximum diameter of the disc to be read, between which the information is contained. A pinion and a gear wheel of the drive unit cooperate with each other without play, in that the pinion is mounted on a pivoting member which is resiliently loaded, so that the pinion and the gear wheel are in resilient engagement with each other. During work on the optical disc player the pivoting member can be pivoted away by hand, so that the teeth of the pinion and the gear wheel are disengaged from each other so that a quick, practically unhampered translational movement of the carriage is possible.

Abstract: In an apparatus for reading a record carrier on which information is stored in an optically readable structure, the radiation which is supplied by the radiation source is split into a read beam and an auxiliary beam for determining the focussing of the read beam on the record carrier. Said auxiliary beam is intercepted by two radiation-sensitive detectors. By disposing a radiation-absorbing knife between the radiation source and the Wollaston prism a part of the auxiliary beam is blocked. Thus, an accurate indication can be obtained of the magnitude and the direction of a focussing error.

Abstract: An electrically controllable carrying arm arrangement for a magnetic disc store and comprising a carrying arm which at one of its ends carries a number of magnetic heads and at its other end is provided with a drive coil with the aid of which the carrying arm is pivoted, so that the magnetic heads are moved over the surface of a storage disc. The drive coil has a flat shape and a small thickness and moves in an air gap between two flat axially magnetized permanent magnets which belong to a stator of the arrangement. Preferably, the drive coil and the carrying arm are disposed in one plane which is perpendicular to the pivoting axis of the carrying arm, so that a compact unit is obtained which demands little mounting height. When a multiple carrying arm arrangement is desired, a plurality of carrying arms of the type described hereinbefore are stacked onto each other with intermediate spacings, while the stator construction is also obtained by stacking a plurality of stators.

Abstract: In an electronic musical instrument with two tone generators of which the frequency of the tones produced by them is substantially constant for the first generator a priori and for the second generator not until after a final value is reached which corresponds to the frequency of the corresponding tone of the first generator, the frequency of the first generator is applied to a first input and that of the second generator to a second input of a frequency comparator circuit, whose output is connected to a control input of the second generator via control device. This ensures that the repeated readjustments of the control quantities necessary in known instruments are no longer necessary.

Abstract: A holder supporting a gas laser holder has two pair of leaf springs, each pair being situated in a plane at right angles to the longitudinal axis of the gas discharge laser and on either side of said laser, thereby isolating the laser device from bending moments as a result of temperature gradients in the laser or holder.

Abstract: When a color television signal is recorded on a video disc and said signal is read a complication arises owing to the asymmetry which is produced in the signal by the various process steps. This gives rise to spurious components whose influence should be minimized by a suitably selected coding system. The invention proposes a device with which the influence of this asymmetry is automatically reduced. This device comprises two separator stages for supplying two sub-signals which respectively represent the rising and falling edges of the information signal. The phase relationship between these two sub-signals is controlled with the aid of a phase shifter. The control signal required for this is produced with the aid of a detector which responds to an asymmetry component in the information signal. The two corrected sub-signals are subsequently recombined to the information signal.

Abstract: A variable resistance device utilizes a control signal variable resistor and a first fixed resistor connected in series as a voltage divider as well as a second fixed resistor and an operational amplifier having an input connected between the first fixed resistor and one side of the variable resistor and an output connected through the second fixed resistor to the other side of the variable resistor, as a substantially linear variable resistance device where the variable resistance is obtained across the voltage divider.

Abstract: The spindle motor of a video disc player is simultaneously disengaged from the motor power source and connected to an electromagnetic safety device for maintaining the cover of the player in a safety position by virtue of the induction current generated by the freely spinning motor until the motor speed is reduced to a safe angular velocity. An electromagnetically operated brake powered by the inductive current generated by the motor assists in reducing the motor velocity.

Abstract: An optical scanning device which scans a rotary video disc with the aid of a light beam comprises an objective which performs focussing movements, for focussing a light spot on a recording surface of the video disc, as well as tilting tracking movements and time-error correction movements. Near its lower end the objective is suspended in an impregnated corrugated loudspeaker diaphragm of fabric fibre which enables the various movements of the objective to be made without giving rise to annoying resonant effects. The tracking movements and the time-error correction movements are obtained with the aid of coils which are connected to the objective near the upper end and which are disposed in air gaps of associated permanent magnetic stators.

Abstract: An apparatus is described for reading an optically encoded radiation-reflecting information carrier, using an opto-electronic focussing error detection system. The path of the read beam which is directed towards the information carrier includes a radiation-deflecting element producing a narrow focussing beam that co-operates with two focussing detectors to produce an error signal.

Abstract: An optical scanning device scans recording tracks on a record carrier with the aid of a beam of radiation, while an objective, which concentrates the beam of radiation to a scanning spot, performs automatic electrically controlled movements in a direction perpendicular to the plane of the record carrier with the aid of a focussing bearing arrangement, so as to ensure a continuous focussing of the scanning spot on the recording tracks. Moreover, in order to follow the oscillations of the recording track, the objective also performs electrically controlled movements which are such that the scanning spot moves at least substantially parallel to the plane of the record carrier.

Abstract: A method of manufacturing an electrically controllable pivoting mirror device for an optical video-disc player, which pivoting mirror device comprises a frame as well as a mirror which with the aid of a plastics bearing with a height of less than 3 mm is fixed to a bearing support. The elastic bearing is first manufactued as a finished part and it is not until after this that it is connected to the pivoting mirror and, as the case may be, to the bearing support. In accordance with a suitable embodiment of the method the bearing is manufactured from chloroprene rubber with the aid of a molding process and is connected to the bearing support during the molding process.

Abstract: A non-recursive discrete filter for simultaneously realizing for example two band-pass filter characteristics starting from a given lowpass transfer characteristic, wherein one bandpass filter has an in-phase transfer characteristic and the other filter the quadrature transfer characteristic of this in-phase filter. The central frequency of these filters is f.sub.o and the output sampling frequency is f.sub.s = 8f.sub.o. This discrete filter comprises multiplying means in which input signal samples x(n) are modified by an associated filter coefficient a(i) for generating modified input signal samples z(n,i) = a(i)x(n-i). The coefficients a(i) are the same for both transfer characteristics and are given by: ##EQU1## WHEREIN H.sub.1 (I) REPRESENTS THE DISCRETE IMPULSE RESPONSE OF THE LOWPASS FILTER.To realize the in-phase transfer characteristic the samples z(n,i) are thereafter multiplied by a factor sgn[cos (.pi.i/4)] and the products thus obtained are accumulated.

Abstract: A light deflector used for tracking a spiral information track alternately and periodically interrupted by data blocks and guide segments arranged within sectors of a rotating record carrier. The light deflector is controlled during the first turn of the information track by a slow analog light deflector having a small stroke and is controlled during the remainder of the recording by a digital light deflector control device having a relatively large stroke.

Abstract: A system for the position control of a write-read head for information carriers with a magnetic storage layer, having optical servo tracks. The servo tracks consist of periodically interrupted lines, whose period length is constant and whose phase relationship differs for adjacent servo tracks. An optical scanner is connected to the magnetic write-read head and is provided with a diaphragm which transmits at the most one line section and at least one overlap between two adjacent line sections to the scanner.

Abstract: An electrically controllable pivoting mirror arrangement comprises a pivoting mirror which is mounted on a frame with the aid of a mirror support and which carries permanent magnetic means at its back for producing a permanent magnetic field for electrical control purposes. Between the pivoting mirror and the permanent magnetic means a mounting plate is located which comprises means for positioning the pivoting mirror and the permanent magnetic means. The mounting plate may also serve for clamping a mirror bearing which is made of rubber-like material or for positioning the mirror bearing when this is glued onto the back of the pivoting mirror.

Abstract: An apparatus is described for reading a record carrier with an optical information structure, in which apparatus errors in the focussing of a read beam on the information plane are detected with an astigmatic focussing-error detection system.By including a beam splitter in the path of a beam which has been reflected by the record carrier and by including an astigmatic focussing-error detection system in each of the paths of the two sub-beams thus obtained, the astigmatism of the one detection system being opposed to that of the other detection system, a focussing-error signal can be derived which is independent of optical faults in the read apparatus.

Abstract: Apparatus for reading a disc-shaped record carrier in which video and/or audio information is recorded in a preferably spiral track. This information is optically read by means of a beam of radiation which via a reflecting element transmits the information present in the scanned point of the record carrier to a read detector. The radial position of the scanning point is controlled by controlling the angular position of the reflecting element which for this purpose is included in a control loop. In order to reproduce the information at a speed different from the recording speed, for example to display slow-motion pictures or still pictures, the reflecting element may be subjected by means of a control signal to an abrupt change in angular position so that the scanning point undergoes an abrupt radial displacement. This displacement preferably takes place during the frame flyback periods of the video information.