Deutsche Thomson-brandt Gmbh

Fritz Ohnemus

Uwe Hartmann

Udo Mai

Gunter Gleim

Franz Dieterle

Gangolf Hirtz

Bernd Bader

Yves Francois

Bernd Tenconi

Eduard Lohmuller

Martin Laufe

A television receiver providing a stable image whether or not a composite color signal is present, in which a transmitter-recognition processes the television synchronization signals of the composite color signal. A character generator displays alphanumeric as well as graphic characters. The deflection generators and the character generator are operative with TV signals as well as characters that are alphanumeric as well as graphic. The deflection generators and the character generator are driven by control signals. An oscillator controls the deflection generators, and a phase comparator operates in the presence of synchronization signals to synchronize the oscillator. The phase comparator receives no signals from the input terminal when no synchronization signals are present, so that the oscillator oscillates at a fixed preadjustable frequency to provide a stable image.

Television receiver with a deflecting oscillator that has the additional

A deflection method and circuit for symmetrical horizontal scanning in a television tube utilizes a vertical deflection coil and an auxiliary vertical deflection coil. The vertical deflection coil is energized with a sawtooth vertical scanning current having a first slope during vertical trace to generate a first vertical deflection field. The auxiliary vertical deflection coil is energized with a sawtooth vertical auxiliary current having a line frequency and a second slope during horizontal trace equal but opposite to the first slope of the vertical scanning current to generate a second vertical deflection field. The first and second vertical deflection fields are superimposed in the tube to produce a stepped vertical deflection field.

Deflection circuit for a television receiver using symmetrical deflection

A reverse feedback amplifier which generates a correction current having two oscillations per line period is used to eliminate geometric distortions on the screen on a television kinescope. The reverse feedback amplifier includes an output transistor, a resonance transformer and a feedback network. An improvement of the amplifier includes a switch and a resistor for decreasing the output voltage of the reverse feedback amplifier during the scanning of the center portion of the screen.

Amplifier with a tuned output transformer

A circuit for demagnetizing a mask in a color picture tube of a television receiver, in which a resistor with positive temperature coefficient is applied to the input alternating current when the receiver is turned on. A bridge rectifier is connected with one terminal, to a first pole of the alternating current source, via the demagnetizing coil that is mounted on the picture tube, and the resistor. The bridge rectifier has another terminal connected to a second pole of the alternating current source. A variable electronic switch interconnects the direct-current output terminals of the bridge rectifier. The variable electronic switch is controlled to continuously decrease current flowing through the demagnetizing coil to zero. For this purpose, a controlling voltage is obtained from a winding in a horizontal-frequency synchronized power-intake stage by flyback rectification. A feedback circuit is connected to a delay network and to the variable electronic switch for opening the latter completely after a time interval determined by the delay network.

Circuitry for demagnetizing the mask in a color picture tube

A circuit for correcting geometrical distortions in reproducing signals on a screen of a cathode-ray tube in a display monitor. A line-frequency correction current having line deflection frequency is coupled into the vertical deflection unit which serves for deflecting vertically electron beams in the cathode-ray tube. A circuit which provides horizontal deflection current is connected to the primary winding of a differential transformer. The differential transformer has a secondary winding connected to the circuit which supplies vertical deflection current. The distortion is reflected by a cathode-ray tube which has a substantially flat picture screen, in which horizontal lines to be displayed form in angle with a horizontal reference grid.

Circuitry for correcting geometrical distortions

A method for generating a voltage with a triangular waveform which is independent of frequency. Two oppositely-phased voltages with sawtooth waveforms are added together in an adding circuit. These two waveforms have different amplitudes, and one of the waveforms has a horizontal section during predetermined intervals of a period. The resulting triangular waveform has points at which the waveform passes through zero, and these points coincide with the points at which the sawtooth waveforms pass through zero also. These points at which the waveforms pass through zero corresponds to 0.degree., 180.degree., and 360.degree. of a waveform cycle for eliminating substantially gullwing errors in television sets. These points correspond to the beginning, center and end of lines in the television sets.

Method of generating a voltage with a triangular wave form

A process for synchronizing horizontal deflection of electron beams in television recievers having a reproduced picture with a visible component, when no transmission signals from a television transmitter are present. If an emitted signal is not available, the synchronization is suspended during the time of the visible picture trace, and is activated only during the picture blanking time. For this purpose, the procedure is to switch off a circuit that synchronizes horizontal deflection during the visible component of the reproduced picture. A synchronization circuit is activated only while the picture is being blanked.

Method of synchronizing the horizontal deflection of electron beams in

A video-display unit in which the beam current of a cathode-ray tube is measured for a predetermined time interval during display of some lines exterior to an image, for establishing automatic cutoff for the electronic beam. This electron beam is defocused during that predetermined time interval, and the defocusing is independent of the contents of the image, so that initial lines are substantially invisible. An electronic switch may be provided for decreasing the focusing voltage of the cathode ray tube. The electronic switch may be a high-vacuum tube connected to the focusing electrode of the cathode-ray tube, or this switch may be a transistor connected through a transformer to the focusing electrode. The transformer may be attenuated.

Picture reproduction apparatus with a cathode ray tube and an

Picture tubes with an extremely flat screen exhibit peculiar geometrical distortions in that the beginning and end of the lines in the picture bend symmetrical to the midline as the result of the magnetic deflection field typical of that type of tube. These distortions, called 'bending errors,' are eliminated in accordance with the invention by coupling another current into the vertical-deflection winding. A current that increases until the horizontal flyback begins is generated 5 to 10 microseconds before the electron beam ends its horizontal forward sweep and an additional current that decreases for 5 to 10 microseconds during the horizontal forward sweep is generated at the end of the horizontal flyback. Eliminating geometrical distortions on the screen of a picture tube.

Method of correcting geometrical distortions on the screen of a

A television set with videotext and/or teletext decoders having character generators which are synchronized by the deflection generators of the television set and in which audio will be forwarded only when an authorized television signal is being received and in that a memory in the decoder will be accessible to display a recognizable image even when the television transmitter is turned off.

Television receiver with receiving devices for processing videotext and

An arrangement for generating a voltage waveform having a triangular shape, in which a first voltage waveform having a sawtooth shape is added to a second voltage that has a sawtooth shape with horizontal components during predetermined intervals of the second voltage waveform. A biased diode bridge applies the horizontal components to the second voltage waveform, which has peaks equal to the peaks of the first voltage waveform. Upon adding the first and second voltage waveforms, a voltage waveform with triangular shape is generated.

Method of generating a voltage with a triangular shape from a sawtooth

A device enables to reproduce without flicker mixed signals from VT and/or BTX decoders during the reproduction of television signals (mixed operation). This is obtained by a video frequency scanning field compensation in the vertical direction effected by a video frequency additional connectable scanning amplifier which supplies a reduced inductivity additional scanning winding.

Growing community of inventors

Villingen-Schwenningen, Germany

Fritz Ohnemus