Abstract: A method of and a device for high-precision moulding of transparent objects is described. Before the object assumes its final shape, a radiation beam is passed through the moulds of a moulding device and the material contained therein, and the intensity distribution of the radiation spot formed by the beam is compared with a reference, thereby enabling the moulds to be aligned very accurately, so that high-quality products can be manufactured.

Abstract: A television camera comprising a control circuit for controlling the electron beam current intensity in a pick-up tube which has a current-controlled electron gun, for example a diode gun. The control circuit comprises a controllable current source an output of which is connected to the anode of the diode gun, which anode acts as a control electrode, and a control input of which is coupled to a pick-up tube output for producing a picture signal. In order to obtain a dynamic additional focussing of the electron beam when an electrostatic focussing means is employed the cathode of the electron gun is connected to a voltage source via a, for example, variable resistor.

Abstract: A device for and methods of measuring and adjusting the convergence of the electron beams in a color display tube of the shadow mask type.The device includes a detector in the form of a divided photosensitive cell comprising at least two separate photosensitive surface parts which are situated symmetrically relative to the center of the cell. The photosensitivity of the surface parts increases substantially from the center of the cell.In use the device is mounted so that the detector is on the central area of the display screen. Three lines are produced in one deflection direction of the tube by means of the three electron beams with one video signal. The central line and detector are moved relative to each other until the longitudinal axis of the line coincides with the center of the cell.

Abstract: An omnidirectional multiple-band antenna for use with a plurality of simultaneously operating transceivers wherein a common conductor mast is excited by a plurality of stub-elements arranged therearound and each sized and spaced to excite a half-wave portion of the mast.

Abstract: A hearing aid includes a duct (10) for transmitting the sound from the receiver (2) to the exterior of the housing (1) of the hearing aid. The duct is formed in a component (9) which is constituted by a body of an elastic damping material and which also serves as the sole suspension means for the receiver (2). The suspension means supports the receiver mainly on that side of the receiver where the sound outlet (12) of the receiver is located. This minimizes the mechanical-acoustic coupling between the receiver and the microphone (3) of the hearing aid.

Abstract: A detachable paper transport device for a printer having a printing roller, using two transport chains. The device has two side walls on each of which a control lever is pivoted for selecting the spacing between the transport chain and the roller, to compensate for differences in the thickness or number of layers of the paper. The device side walls each have a slotted hole for engaging one member on the printer, and each control lever has a bearing lug for engaging another member on the printer to slide the device along the slotted holes.

Abstract: The invention relates to a method of reproducing plastics record carriers, in particular duplicating video records. According to the invention, a metal die is used which is provided with a thin-liquid molding resin of a particular composition which can be polymerized by radiation. A radiation-pervious substrate which is manufactured from synthetic material, for example polymethylmethacrylate, is provided on the molding resin. The molding resin is exposed to light via the substrate after which the cured molding resin together with the substrate connected thereto is removed from the die. The molding resin used in the process comprises low-molecular monomers or oligomers which contain on an average 25-70% by weight of hydrocarbon groups and/or phenyl groups. The molding resin is aprotic and has a functionality as regards unsaturatedness which is between the values 2 and 6. A suitable molding resin contains mono-, tri- or tetra esters of acrylic acid.

Abstract: Optical transmission system comprising a laser diode which is coupled to a transmission fiber via a coupling path. The coupling path includes a monomode fiber or the series arrangement of a monomode fiber and a pluraity of multimode fiber lengths, the cross-section of which, see from the laser, increase in size. As a result thereof the modal noise and the reflection noise in the optical system in drastically reduced.

Abstract: Low-pressure sodium vapor discharge lamp. The lamp comprises a cylindrical discharge tube and an outer bulb enveloping this tube. The outer bulb has a transparent layer which reflects infrared radiation.According to the invention the resistance per square of the infrared reflecting layer is approximately 5 ohm. A luminous efficacy of 100 lumen per watt can be obtained at a lamp power of 8 watts. The lamp is particularly suitable for security lighting.

Abstract: Glasses consisting of 45-55 mol. % P.sub.2 O.sub.5, 15-40 mol. % BaO, 5-15 mol. % Li.sub.2 O, 5-35 mol. % PbO, 0-2 mol. % Al.sub.2 O.sub.3 and 0-6 mol. % F are suitable for the precision pressing of lenses.

Abstract: A low-noise bass-control device, which is digitally controllable in a simple manner, comprises an amplifier having an output connected to the series arrangement of a capacitor and a tapped resistor chain. The taps on said resistor chain are connected to an inverting input of the amplifier via a first switch and to the output of the control device via a second switch.

Abstract: For transferring a logic signal between a first stage and a second stage at higher level in an integrated current injection logic circuit formed by superimposed layers which are biassed with different voltages (for example an I.sup.2 L logic circuit), the collector of a first transistor at the output of the first stage controls the base of a first auxiliary transistor, whose collector is connected to the base of a second transistor, which provides the connection to the input of the second stage. In order to rapidly drain the charge stored in the base of the second transistor, said base is connected to the base of a third transistor, whose collector is connected to its base so as to form a current mirror. The switching time of the device in accordance with the invention is thus substantially reduced.

Abstract: A reproducing apparatus for information signals recorded in inclined tracks together with tracking signals whose frequency changes from track to track in a cyclic sequence, comprises a variable-frequency signal generator for the generation of track selection signals, from which together with the crosstalk tracking signals reproduced during a playback mode by at least one rotatable playback head arranged on an electromechanical transducer a transducer actuating signal is derived for tracking purposes, by means of which actuating signal the transducer with the playback head is adjustable between two extreme positions transversely of the tracks.

Abstract: A control device for a stepping motor provided with a coil and a rotor performing a rotary movement when a current passes through the coil, comprising means for producing a plurality of time base signals, means for producing pulses for controlling the motor in response to said time base signals, means responsive to the control pulses for supplying the motor while maintaining the current in the coil at a substantially constant and given value. The device also comprises means for analyzing the voltage signal present on the coil or a signal which is representative thereof, and for supplying data concerning the voltage induced in the coil by the rotor movement.

Abstract: A method of providing grooves in a body of a soft-magnetic, iron-containing material. The method includes reactive ion etching the body in a chlorine-containing or bromine-containing plasma after providing the body areas not to be etched with a mask of an inorganic material such as Al.sub.2 O.sub.3.

Abstract: An optical fiber of the graded index type consisting of a glass having predominantly the composition 60-70 mole % SiO.sub.2, 15-30 mole % alkali metal oxides, and 10 to 15 mole % MgO in combination with at least one oxide selected from the group formed by CaO, SrO, BaO and ZnO. The impurity content of the fiber is less than 0.01 ppm. In the fiber the MgO content increases from the axis of the fiber to the circumference of the fiber. The oxide or the other oxides, having cations which can be exchanged for the magnesium cation, decrease to a corresponding extent in this direction.

Abstract: A swing arm arrangement includes at least one magnetic head provided on at least one swing arm of a magnetic disc store. The swing arm has a recess formed by walls whose facing portions cooperate with opposite portions of a single stop cam to limit the pivotal movements of the arm.

Abstract: In X-ray tubes comprising a metal grid, it may occur that the necessary emission current cannot be reached in unfavorable circumstances. This situation is improved by the invention in that the high voltage for the X-ray tube is derived from at least three series connected high voltage generators, the first and the second generator being connected to the anode and the cathode, respectively, of the X-ray tube while the third generator can be connected either to the anode side (in the case of high tube voltages) or to the cathode side (in the case of low tube voltage) by means of a switching device.

Abstract: A magneto-optical memory element consisting of a substrate, provided with an amorphous layer of an alloy of a rare-earth metal and a transition metal. The layer has a uniaxial magnetic anisotropy. Such memory elements are suitable for storing digital information in the form of magnetized areas, the magnetization direction of which can be read by means of the Kerr effect or Faraday effect. By adding bismuth and/or tin to the alloy the Kerr rotation and Faraday rotation can each be increased considerably, so that simpler reading of the stored information is possible.

Abstract: For the reliable guiding of a record carrier and the printing thereon as far as in the vicinity of the upper and lower edge, a pivotable device is arranged over the printing drum, said device comprising two or more flat hold-down devices which are arranged on a rotatable shaft. The hold-down devices can be slid into a first position in which they engage the printing drum and a second position in which they are lifted off the printing drum. In the first position, the record carrier is deflected to the printing drum during transport, and in the second position it is transported by additional pressure rollers. The device is pivotable about the printing drum into three positions and is constructed as a modular unit. This enables the simultaneous or alternating transport about the printing drum of different record carriers in a different manner.