Abstract: A conference system comprises speaker units (12) coupled to a central unit (14). The speaker unit (12) comprises an echo canceller (20) with an adaptive filter (38) having an impulse response of comparatively short duration. In a speech pause of the user of the speaker unit (12) the common listening signal (LS) of the conference system is applied to the loudspeaker (18). Of the sounds then picked up by the microphone (16) only those sounds are compensated which are produced by the loudspeaker (18) and which reach the microphone (16) directly and which reach the microphone (16) indirectly via reflections from nearby objects. These sounds have a comparatively short impulse response time and enable a comparatively simple adaptive filter (38) to be used. The other sounds picked up by the microphone (16) reach the microphone (16) via reflections from the walls of the conference space (10) in which the conference system is situated. The other sounds have a comparatively long impulse response time.

Abstract: An echo canceller for use in send/receive apparatus includes a frequency-domain adaptive filter which provides filter parameters to a time-domain programmable filter. The programmable filter produces a signal y(k) which is an estimate of the echo signal produced by acoustic coupling between a loudspeaker in the received path and a microphone in the send path. By subtracting this estimate from the signal produced in the send path, an output signal r(k) is obtained from the send path which is essentially free of echoes. An accurate estimate of the echo signal cannot be obtained if a send signal is present at the input of the send path. Therefore, detecting means in the adaptive filter detects whether such a send signal is present and in that case blocks the transfer of filter parameters from the adaptive filter to the programmable filter. Erroneous modification of the estimated echo signal is thereby avoided.

Abstract: An appliance for infusing a substance, for example coffee, comprises means (23, 16) for dividing an initial quantity of water into a pre-wetting quantity and at least one additional quantity, which quantities are poured on in at least two steps which are spaced in time. Means (20a, 20b, 22) for continuously measuring the level of the water to be poured on enable several dividing programs to be selected.

Abstract: Method of recording information, recording element manufactured according to the method and method of producing a metal matrix.Recording in which a recording double layer which has an absorbing dye is exposed to laser light of a higher and a lower energy level, in which by exposure to laser light of the lower energy level, a bump is formed in the recording layer and in which by exposure to laser light of the higher energy level a bulge is formed which at the surface comprises a groove, as well as a recording element obtained by using the method and a method of manufacturing a metal copy from the recording element.

Abstract: An a.c. to low voltage d.c. converter includes a pair of input voltage supply lines (Vin,OV) and a semiconductor switch element (T1) and a capacitor (C1) connected in series between the supply lines. An output (Vo) for d.c. voltage is provided across the capacitor (C1). A sensing circuit (10) is responsive to the input voltage and is arranged to trigger the switching element (T1) to conduct only during a portion of the a.c. voltage below a predetermined voltage.

Abstract: The high-pressure discharge lamp has an ionizable filling containing mercury, rare gas, dysprosium halide and a second halide chosen from the halides of Tl, Ce, Pr, Nd, Sm and Gd. The lamp has a comparatively low color temperature and a good color rendition, especially also of the color of the skin. The lamp may be used, for example, as a studio lamp for the illumination of indoor scenes.

Abstract: The invention relates to a method of generating a layer image from a plurality of single images, the image processing errors which locally occur in the single images being substantially eliminated in the layer image. To this end, the image values for the individual layer image points are formed by that image value of the image points geometrically situated with the layer image point which corresponds to the next to the lowest absorption value.

Abstract: The assembly has a low-pressure sodium discharge lamp (1), of which the outer envelope (4) has an electrically conducting coating (5), which is connected through a capacitor (29) to one of the current supply conductors (13) to the light source (3) of the lamp (1) and to the neutral conductor (18) of the power supply (2), which supplies an alternating voltage having a frequency of at least 80 kHz. The lamp holder (23) has an eccentrically arranged projection at its inner surface while the lamp cap (6) has an eccentrically arranged recess at its outer surface, which, when the lamp cap (6) is arranged in the lamp holder (23), engage with each other and guarantee a connection of the capacitor (29) to the neutral conductor (18). The lamp (1) is suitable for operation at mains voltage frequency and is still fitting into the lamp holder of mains voltage frequency equipment.

Abstract: A color display tube in which the bridges between the apertures of the color selection electrode are situated substantially on substantially straight lines in the plane of the color selection electrode, which lines enclose an angle between 3.degree. and 8.degree. with the horizontal direction of deflection, effectively suppressing the occurrence of moire-patterns.

Abstract: In a digital demodulation circuit for a chrominance signal of a color television signal having a first digital oscillator (35) for producing reference signals and a phase control loop (29, 17, 19, 49, 43) therefor, there is added in the phase control loop a signal combination (at 56) which is obtained from a phase control loop (67, 63, 59) of a second digital oscillator (77). This second digital oscillator derives the sampling frequency for sampling the chrominance signal from a signal source (83) of a constant frequency and couples this sampling frequency to the horizontal deflection frequency. By the addition in the phase control loop of the first oscillator, variations in the horizontal deflection frequency cannot lead to the undesired phenomenon of the first digital oscillator being pulled to a side-band frequency of the color subcarrier wave.

Abstract: An analog current switch in bipolar technology in which an intermediate transistor (T.sub.i), which isolates the current injector (S) from the switching diode (D.sub.c), is biassed by means of a transistor (T) whose collector, which is coupled to its base, is connected to the base of the intermediate transistor (T.sub.i) and to the anode of a diode (D), the emitters of (T) and (T.sub.i) as well as the cathodes of (D) and (D.sub.c) being interconnected.

Abstract: In a logic circuit arrangement comprising a plurality of sticks formed by series arrangements of transistors which receive the signals to be processed a conductive stick not only has to discharge the output capacitance of the logic output but also other sticks which are not completely conductive, namely up to the first cut-off transistor. This may result in a very high capacitive load, which substantially reduces the maximum attainable switching speed. In accordance with the invention an additional transistor is arranged between each stick and the output of the entire logic circuit, which transistor receives a gate voltage such that current flow from the cut-off charged sticks via a conductive stick is prevented or delayed until the output signal of the logic circuit has assumed a value which unambiguously switches over the next output transistor.

Abstract: The position of an optical or opto-electronic component, such as a lens or a plate provided with a number of light-sensitive semiconductor diodes, can be adjusted in two directions of adjustment which are perpendicular to each other with the aid of an appropriate adjusting device. The adjusting device comprises two bending hinges consisting of portions of a leaf spring, which bending hinges are perpendicular to each other, the one hinge being bent relative to a stationary frame to which the adjusting device is secured and the other bending spring being bent relative to the first bending spring. The two bending springs may consist of portions of a single unit manufactured from a suitable spring material.

Abstract: A receiver in which the detection sensitivity of a detection diode is adjustable as a function of the polarization current, and is controlled by means of a feedback circuit provided with a delay element so that changes in the received signals having a frequency below a value determined by the delay element are eliminated.

Abstract: A device in which focussed ultrasonic beams are used by way of binary distribution of the phase of the signals occurring in a mosaic of transducers. The material of which the transducers are made can be polarized, which enables the prefocussing of the ultrasonic beam to be transmitted or received, and also enables point-wise scanning and scanning by double focussing according to the X-direction and the Y-direction.

Abstract: A device for analysing a surface layer by means of ion scattering. The device comprises an energy selector having two coaxial cylindrical electrodes. A primary mono-energetic ion beam impinges upon the surface layer and its axis coincides with the axis of the cylindrical electrodes. Back-scattered ions, the paths of which lie on a conical surface having an apical angle of 180.degree. reduced with the scattering angle, are selected for energy and detected.

Abstract: A new integrated circuit in which bias currents are supplied by means of a current injector, a multi-layer structure in which current is supplied, by means of injection and collection of charge carriers via rectifying junctions, to zones to be biased of circuit elements of the circuit, preferably in the form of charge carriers which are collected by the zones to be biased themselves from one of the layers of the current injector. By means of said current injector circuit arrangements can be realized without load resistors being necessary, while the wiring pattern may be very simple and the packing density of the circuit elements may be very high. In addition a simple method of manufacturing with comparatively few operations can in many cases be used in particular upon application of transistors having a structure which is inverted relative to the conventional structure.

Abstract: A single entrance prism and two symmetrical second prisms divide the radiation from an object into two light paths and angularly correct the rotation of the image planes for a binocular viewing system.

Abstract: In a color television camera system of the type having camera tubes for the production of red, green and blue color signals, contour signals derived from only one of the color signals are added to all of the color signals.