Abstract: A method for adjusting convergence in a projection television receiver, in which a marker contained in a projected image is adjusted by a manipulated variable to illuminate a photosensor arranged adjacent to the projection screen. The method employs two markers which are moved towards the sensor from opposite directions with a varying step size. The sensor supplies an output voltage indicating lighting by the two markers in conjunction with two mutually spaced manipulated variables. A mean value of the two manipulated variables is used as the manipulated variable for the marker.

Abstract: A method for convergence correction in a projection television display having a monochromatic tube for each of the three primary colors red, green and blue, whose images can be projected on a screen. Each tube has an associated deflection correction device which comprises a convergence circuit. Convergence correction values are determined by measurement using sensors with screen edge locations which cannot be seen. Convergence correction values are calculated for the entire screen by interpolation between these values.

Abstract: A method for adjusting convergence in a projection television receiver, in which a marker contained in a projected image is adjusted by a manipulated variable to illuminate a photosensor arranged adjacent to the projection screen. The method employs two markers which are moved towards the sensor from opposite directions with a varying step size. The sensor supplies an output voltage indicating lighting by the two markers in conjunction with two mutually spaced manipulated variables. A mean value of the two manipulated variables is used as the manipulated variable for the marker.

Abstract: A Circuit for convergence setting in a projection television display, having a display screen with a photosensor for detecting impingement of a marker contained in a projected picture. The photosensor generates an output signal having a specific time characteristic. The circuit comprises an integrating element coupled to receive the output signal from the sensor when impinged by a blue marker. The integrating element is dimensioned in such a way that the time characteristic of the output signal of the sensor when impinged by the blue marker is approximately equal to the time characteristic of output signals from the sensor when impinged by a red or green marker.

Abstract: A set of coarse or initial convergence correction values for a model line of projection television receivers is defined in digital form prior to production using a fine grid or grating pattern. The set of coarse convergence correction values is digitally stored in all the receivers of the model line. A receiver-specific set of fine or final convergence correction values is defined in digital form for each receiver in the model line using a coarse grid or grating pattern. In each receiver, the receiver-specific set of fine or final convergence correction values is combined with the stored set of coarse convergence correction values. Convergence correction during subsequent operation of each receiver is based on the combined convergence correction values. Some of the coarse and fine convergence correction values can be located horizontally outside of the visible picture area of the receivers.

Abstract: An apparatus for electron beam deflection in a cathode ray tube, in particular in a picture tube of a television set, comprises a deflection coil arrangement for horizontal and vertical deflection of the electron beam, an auxiliary deflection coil arrangement, by means of which the electron beam can be influenced for the purpose of convergence correction, and a compensation coil arrangement for producing a magnetic compensation field. The compensation coil arrangement is arranged and designed such that the compensation field essentially compensates for the stray magnetic field of the deflection coil arrangement in the physical region of the auxiliary deflection coil arrangement.

Abstract: When a power supply unit supplies power to a plurality of power amplifiers, an appreciable power loss is produced in the power supply unit and in the amplifiers. According to the present invention, the output voltage of the power supply unit is regulated so that it is high enough at any instant for the amplifier which at that instant has an output signal having the largest amplitude.

Abstract: A projection television apparatus has three monochromatic picture tubes disposed in a planar orientation defining a central picture tube and two outer picture tubes. Each of the picture tubes includes a deflection unit responsive to deflection currents and raster correction signals for vertical and horizontal deflection. A control circuit, including a signal generator, supplies vertical and horizontal raster correction signals formulated for the central picture tube to all three of the picture tubes and supplies additional vertical and horizontal raster correction signals formulated for the two outer picture tubes respectively to the two outer picture tubes, respectively. Conductive paths for the formulated for the central picture tube correction signals can include variable resistors for effecting small changes in signal amplitude.

Abstract: A method of collecting the spactial positions of crossing points of the lines in the grid on the visible portion of the screen of a television receiver used in different modes of operation includes the steps of storing a first set of correction values for each of the crossing points. The first correction values define the spactial positions of the correction points for all modes of operation of the television receiver. Additional correction values are stored for each mode of operation. The additional correction values are generated during an overscan period and during the scanning of an initialization line which is positioned outside the visible portion of the screen and compensate for displacement of the crossing points induced by tolerances in the tube. The first correction values and the additional correction values are simultaneously applied to the deflection current of the television tube while the visible portion of the screen is scanned.

Abstract: A cursor for correcting the locations of points formed by the crossing horizontal and vertical lines of a grid arranged on the screen of a television receiver. The screen has a portion illuminated by a picture and a dark portion unilluminated by the picture. The grid also has at least one line of dark-points parallel to each edge of the picture and lying outside of the picture. The cursor is configured and dimensioned to extend into the picture when the cursor covers one of the dark-points.

Abstract: A method of positioning a light beam on a picture surface relative to a light sensor located on the picture surface includes the step of completely illuminating the sensor with the light beam while the sensor is exposed to ambient light and recording a first output signal. A second output signal is recorded when the sensor is exposed to only ambient light. The first and second output signals are provided to an evaluation circuit to calculate a positioning signal having a value equal to a selected percentage of the difference between the first and second output signals.

Abstract: A system for making location adjustments on a display screen raster having horizontal and vertical lines crossing at crossing points includes a cursor which is moveable to the crossing points. The visibility of the cursor is enhanced because the horizontal and vertical lines are brighter than the cursor. The visibility of the cursor can be further enhanced by making the brightness of the cursor adjustable.

Abstract: Convergence correction waveforms are generated for multiple vertical formats. One of a number of vertical formats is selected for displaying a video signal. The vertical formats differ by respective vertical scanning rates, respective vertical scanning heights, or both. A set of convergence correction values corresponding to a plurality of raster locations is stored for each of the different vertical scanning heights. An interpolation control value is stored for each of the vertical scanning frequencies. An interpolator is responsive to different ones of the control values for generating a different set of intermediate convergence correction values for each of the vertical scanning frequencies, from each of the sets of stored convergence correction values. The interpolator generates the intermediate convergence correction values between horizontally and vertically spaced ones of the raster locations.

Abstract: A television apparatus comprises a video display having a wide format display ratio, for example approximately 16:9. A deflection circuit generates first and second selectable rasters having a common horizontal scan width corresponding to the display but having first and second vertical heights respectively, for example nominal and overscanned vertical heights. A control circuit selects one of the first and second rasters for displaying pictures from wide format display ratio video sources and conventional format display ratio video sources respectively, for example 16:9 and 4:3. A picture from the wide format display ratio video source is substantially uncropped and a picture from the conventional format display ratio video source is expanded and cropped. One of the vertical formats provides substantially no image aspect ratio distortion of the pictures as displayed. The other one of the vertical formats provides substantially no cropping of the pictures as displayed.

Abstract: The resonant frequency of a quartz-crystal microwave oscillator is the fundamental frequency in the partial mode of the crystal and makes it possible to maintain the loaded Q of the resonator at a high value. This microwave oscillator is provided with two amplifying stages and has a signal-to-noise ratio of the order of 160 dB.

Abstract: The invention concerns a very high frequency quartz oscillator. The feedback loop of the oscillator comprises a compensation network of a quartz at the frequency of the oscillator, and a low-pass filter eliminating the frequencies lower than that of the oscillator. A power divider having two branches allows to send the signal issuing from the feedback loop, on the one hand, to the amplifier input of the oscillator and, on the other hand, to the output amplifier. Two-port networks Q.sub.1 to Q.sub.6 match the impedances at the input and at the output of the amplifier of the oscillator, of the feedback loop and of the output amplifier.

Abstract: A method and a device for regulating the heating of a thermostatically controlled enclosure of a quartz oscillator. During a first stage, the thermostatically controlled enclosure is exposed to an external temperature close to the maximum operating temperature and the frequency of the oscillator is measured. During a second stage, the thermostatically controlled enclosure is exposed to an external temperature close to the minimum temperature of the range and the difference between the frequency of the oscillator and the frequency previously measured is cancelled out by modifying the distribution of the powers dissipated by the heating elements of the thermostatically controlled enclosure. The heating of the enclosure is performed by a chain of voltage stabilizer semiconductor circuits connected in series, each of the circuits being traversed by a regulated heating current. The regulating of the heating action is performed by modifying the stabilized voltages of the circuits.

Abstract: The subject of the invention is a high frequency bandpass amplifier with adjustable impedance, in particular for a high frequency quartz resonator. It includes a transistor T connected in common base the emitter of which is connected to ground by a resistive divider bridge (R.sub.2, R.sub.1) the mid-point of which forms the input of the amplifier. The collector of the transistor (T) is connected to ground by a parallel circuit (LC) having one inductive side (L) and one capacitive side (C), a mid-point of the inductive side (L) or of the capacitive side (C) forming an output (s.sub.1 or s.sub.2) of the amplifier (A). The base of the transistor is biased and connected to ground via a capacitor (C.sub.3) ensuring common base operation in the pass-band of the amplifier. The invention also relates to an oscillator of transmission type including such an amplifier and a resonator (1) connected between the input (e) and one output (s.sub.1 or s.sub.2) of the amplifier (A).