Abstract: An optical scanning device is described which comprises a radiation source (6), an objective system (8) and a diffraction grating (9) which is arranged between the objective system and the radiation source to separate the radiation beam (b') reflected by the information surface (2) to be scanned from the beam (b) emitted by the radiation source and for introducing astigmatism in the reflected beam (b') for the purpose of focus-error detection. In principle, the grating (9) has a constant grating period and is arranged at a small angle (.alpha.) in the beam (b').

Abstract: The invention relates to an apparatus for playing back and/or recording information on rotary optical discs comprising a device for clamping the optical disc in position on a disc aligner mounted on a rotating spindle. The clamping device comprises a disc loader which moves with clearance in a support which is movable between a rest position and an operating position. The disc loader exerts a clamping force on the disc during operation due to a magnetic force between magnets secured to the disc loader and the support. Rattling and an oblique position of the disc loader are precluded in that the magnets are arranged to exert a magnetic force which acts between the support and the disc loader so as to clamp the disc loader against the support when the latter is not in its operating position.

Abstract: A zero-IF receiver for an FM signal comprises quadrature-mixers (2,3) to which the input signal is applied and which mix the received carrier down to zero frequency. The signals appearing at the mixer outputs (11,12) are fed to a differentiate, multiply and subtract demodulator (22,23,25,27,31) via capacitors (17,19) which block the d.c. components of the signals, thereby preventing amplifier saturation effects, etc. This d.c.-blocking would, unless steps were taken to prevent it, result in distortion of the output signal appearing at an output terminal (32). This distortion is prevented by providing an amplitude divider (33) in the output signal path.

Abstract: The invention relates to a method and system for determining an image of a nuclear magnetization distribution in a body. In known methods, particularly in nuclear spin echo techniques, a resonance signal is generated which has high dynamics. In the method according to the invention dephasing is effected which is non-linear place-dependent or which is frequency-dependent within a spectroscopy distribution, as a result of which the generated resonance signal will have a much smaller amplitude. Since the non-linear dephasing applied within the distribution is known, a correction can be made for this after the determination of the measuring signals.

Abstract: The invention relates to a high-pressure discharge lamp comprising a discharge vessel (3) enclosing a discharge space (3b) and provided with two main electrodes (4,5). Each of the main electrodes is connected to a lead-through member (40,50), which is enclosed with a clearance space (10) by a closing part (30) and is connected thereto by means of a melting glass connection (9) in a gas-tight manner. According to the invention, the lead-through member is provided with a proturberance (51) reaching as far as the closing part in such a manner that the lead-through member (50) is passed with a clamping fit through the ceramic closure member. Thus, the lead-through member is fixed, as a result of which the manufacture of the lamp is considerably simplified.

Abstract: Base radio stations are spatially arranged in a radio transmission system in accordance with a cellular system, separating the message transmission channels from adjacent base stations being effected either by using the frequency-division multiplex method or by using the code-division multiplex method or by using a combination of these multiplex methods. In appropriately large spatial distances the same set of channels can be repeated in a further radio cell. If a mobile radio station moves during the conversation from one radio cell into another, then it is necessary to hand-over the then existing radio connection. To avoid the necessity of using additional receivers in each base station and to prevent a repeated hand-over in the event of high co-channel interferences, the measurements used for hand-over decision are effected in the mobile radio station.

Abstract: The invention relates to an optical demultiplexer whose "color band" is adjustable, so that the demultiplexer can always be adapted to future standards. The adjustment is performed either by tilting the optical grating with respect to the light beam incident thereon or by deflecting the light by means of a liquid crystal arranged in the light path.

Abstract: The vertical viewing angle of a rear projection screen having a large horizontal viewing angle and good color correction due to the special shape of the light dispersing elements provided on the front side of the plate is increased by elements provided on the rear side and extending in a direction perpendicular to the front side elements. The latter are preferably total internal reflection elements, while the former are not. A bulk diffusor may be largely or completely dispensed with.

Abstract: A device is described for determining a centring error of a track-shaped information structure in an optical record carrier relative to an axis of rotation of a turntable. The device comprises at least one radiation source and at least one radiation-sensitive detection system with at least two detectors. The output signals of the detectors provide an indication of the direction in which the radiation from the radiation source which is diffracted in a first radial order b(-1) by the information structure. This in turn gives an indication of the position of the center of the track structure. This device enables optical record carriers without center hole to be used.

Abstract: This device comprises a high-frequency signal generator (5) fitted with a modulation control input (10) to supply said pulses at its output in relation to a modulation signal applied to its modulation input and a modulation generator (15) to provide the modulation input with the modulation signal. This device also includes a replica circuit (18) to supply a replica of the pulse transmitted, a management circuit (25) to compare this replica wtih said pattern and to alter the modulation signal from the modulation generator so that the pattern complies with the replica.

Abstract: The invention relates to a circuit arrangement for controlling an oscillator. In a first phase-comparator circuit a burst signal whose phase alternates in a predetermined sequence is compared with a first oscillator signal. The output signal generated by the first phase comparator circuit is superimposed on a correction signal generated in a correction circuit, so as to eliminate fluctuations as a result of the phase alternation of the burst signal. The correction circuit is disabled when the magnitude of the phase difference exceeds a specific limit value.

Abstract: The edges of an incoming video signal are sharpened by switching the output furnishing the sharpened signal in sequence first to receive a signal delayed by a greater amount, i.e. a signal which has not as yet undergone transition, and, secondly, to receive a signal delayed by a lesser amount, i.e. one that has already completed the transition. The rise time of the affected edge thus depends only on the time required to switch from one terminal to the next. The same switching sequence is carried out regardless of whether the transition is a negative going or positive going transition.

Abstract: A fully integratable bridge amplifier comprises two identical amplifiers (1; 5) each being provided with a first input stage (20; 40) whose inputs constitute the first non-inverting inputs (2; 6) and the first inverting inputs (3; 7) of the amplifier, a second input stage (29; 50) whose inputs constitute the second non-inverting inputs (28; 49) and the second inverting inputs (27; 48) of the amplifier, and an output stage (25; 45). The first inverting input (3; 7) of each amplifier (1; 5) is connected to the output (12) of a buffer amplifier (9) via a first resistor (R.sub.6 ; R.sub.9) which together with a second resistor (R.sub.5 ; R.sub.8) constitutes a negative feedback network between the output (4; 8) of the amplifier (1; 5) and the first inverting input (3; 7). The first non-inverting input (2; 6) is also connected to the output (12) of the buffer amplifier (9). This output (12) and consequently the first inputs (2, 3; 6, 7) of the amplifiers (1; 5) are at half the supply voltage with respect to the d.

Abstract: The electric lamp has a lamp vessel of which a wall portion is mirror-coated at its inner surface with an aluminum layer. This wall portion has a boundary near the largest diameter of the lamp vessel. This boundary is adjoined by a thermally connected zone having a transparent aluminum oxide layer. In the lamp, a dark zone caused by a very thin aluminum layer adjoining the boundary is avoided.

Abstract: The irradiation device comprises a short arc discharge lamp, in which a pair of electrodes are arranged, between which a discharge path extends. An optical conductor is sealed with its first end into the wall of the lamp vessel in such a manner that its light entrance window is arranged laterally of the discharge path and is directed to the discharge path.

Abstract: The invention relates to a high-pressure sodium discharge lamp intended to be operated in conjunction with an external starter or with an internal starter without a glow discharge. The lamp has an outer bulb which is provided with a lamp cap and encloses an evacuated space in which a discharge vessel is arranged. According to the invention, the space enclosed by the outer bulb further accommodates a closed holder, whose wall mainly comprises glass-forming constituents and which contains at least helium. Thus, it is achieved that the lamp has a strongly reduced increase in lamp voltage during the life.

Abstract: During known MRI measurements, for example spin echo and inversion recovery measurements, phase errors occur in pixels, inter alia due to eddy currents caused by the application or interruption of magnetic field gradients during a measurement. There is proposed an inversion recovery method combined with a method where the magnetization is not inverted in advance in order to determine for each pixel the phase error in an image obtained by means of an inversion recovery method, so that inversion recovery images can be obtained which do not contain phase errors.

Abstract: Method of digital radio transmission between a base station and a plurality of mobile stations. A time division multiplexed signal frame is generated, including a plurality of time slots which repeat each frame interval. A beginning number of the time slots form a signalling channel with the remaining following time slots forming a plurality of channels which receive data to be sent. The signalling channels include a common organizational connection for each channel of the frame. Additionally, one of the remaining plurality of channels includes an organizational channel for identifying a larger number of channels than those included in the individual frame. The technique permits a combination of time division multiplexing, spectral multiplexing and carrier frequency multiplexing.