Sgs-thomson Microelectronics S.a.

Stmicroelectronics S.a.

Thomson Semiconducteurs

Marelli Autronica

Jean-Michel Moreau

Jean-Pierre Lusinchi

A control circuit of a power supply delivering a supply current to an inductor connected in series with the horizontal deflection yoke of a cathode ray tube display, the inductor being the primary coil of a transformer operatively connected for delivering a rectified low-pass filtered biasing voltage to the anode of the display, the low-pass filtering having a first time constant corresponding to the duration of a plurality of pictures, the control circuit having feedback circuitry for generating a monitoring voltage substantially proportional to the biasing voltage and for controlling the supply current to keep the monitoring voltage equal to a reference voltage; and feedforward circuitry for measuring the cathode current and for adding to the monitoring voltage a compensation voltage corresponding to the cathode current, low-pass filtered with a second time constant corresponding to the duration of a small number of lines and high-pass filtered with the first time constant.

Control circuit and process for a cathode ray tube display control apparatus

The invention concerns a control circuit for an electron tube display comprising a deflection coil, the deflection coil being part of a scanning circuit and being coupled to a coil of a transformer powering a high voltage generator used to accelerate an electron beam, a phase locked loop being used to keep in phase the flyback pulses produced by the scanning circuit and the video signal synchronisation pulses, and comprising an electron beam current measuring circuit, a compensation circuit for compensating the phase difference between the flyback pulses and the video signal synchronisation pulses as a function of the measured current.

Scanning circuit of electron tube displays

The invention concerns a scanning circuit, comprising a power supply providing a negative voltage on a first terminal (Tdown), an intermediate voltage on a second terminal (Gnd) and a positive voltage on a terminal of a switch (S), the other terminal of the switch being connected to a third terminal (Tup), a control circuit () supplied by connections to the second and third terminals, a differential amplifier receiving a positive and a negative input signal provided by the control circuit, a power amplifier controlled by the differential amplifier, both amplifiers being supplied by connections to the first and third terminals, a deflection coil (Ly) connected between the output of the power amplifier and the second terminal, biasing means setting, when the switch is open, the output of the differential amplifier so that the possible current paths through the power amplifier between the deflection coil and the first terminal are cut.

CRT vertical scanning circuit with a low power standby

A line scan circuit for a CRT, including, in series across a switch, two oscillating circuits having the same time constant, each including, in parallel, a capacitor, a diode connected in antiparallel, and a series association of an inductor and of a voltage source, the inductor of a first one of the oscillating circuits being a scan coil of the CRT; an amplifier receiving a set-point voltage and using, as a feedback, a voltage taken from one of the oscillating circuits, and providing an adjustable voltage source to the second oscillating circuit.

CRT scan circuit with a geometry correction independent from the scan frequency

A circuit for providing a rectified voltage to a flyback switch-mode supply circuit comprises a rectifying bridge having output terminals; a primary winding of the switch-mode supply having an intermediate tap; a switch serially connected with the primary winding; the serial connection between the output terminals, of a first diode and a capacitor, the first diode being biased so as to allow the charging of the capacitor; a second diode between a first output terminal of the winding, the second and third diodes being biased so as to let the current flow towards a second terminal of the winding.

Switch-mode supply with power factor correction

A multistandard rectified supply circuit comprises, across a full wave rectifying bridge, at least one storing element associated with a charge path comprising first unidirectional conductive elements of a first polarity and with a discharge path comprising second unidirectional conductive elements of a second polarity so that the storing means is differently charged and discharged. A switch cancels the effect of at least one of the first and second unidirectional elements so that the storing element is charged and discharged through a same path.

Multistandard rectified power supply circuit

A method and apparatus for providing a rectified voltage to a flyback switch-mode supply circuit with power factor correction is disclosed and claimed. The invention comprises a rectifying bridge and a charge path for charging a capacitor from the rectified voltage obtained from the output of the bridge. The degree of power factor correction is achieved by selecting a time at which either the rectifying bridge output or the capacitor provides a voltage to the supply circuit. The input to the supply circuit is a primary winding having n1 turns between an upper and intermediate tap, and n2 turns between an intermediate and lower tap. The capacitor is connected to the upper tap via a diode, a first rectifying bridge output is connected to the intermediate tap via a diode, and a second rectifying bridge output is connected to the lower tap via a controllable switch. When the rectified voltage is greater than a threshold voltage related to the peak rectified voltage by the ratio n2/(n1+n2), the rectifying bridge outputs provide the voltage to the supply circuit. When the rectified voltage is lower than this threshold voltage, the capacitor provides the voltage to the supply circuit. In this manner, the timing of sources providing voltage to the supply circuit and hence the degree of power factor correction is determined by the ratio of the primary winding turns n1 and n2.

Power supply circuit with a storage capacitor

A signal transmission circuit for transmitting signals having a wide frequency spectrum over a cable. The circuit includes an isolating transformer having a high pass filtering function; a low-pass filter, the input of the low pass filter being common with the input of the high pass filter; and means for summing the output voltages of the low-pass filter and the high-pass filter.

Signal transmission circuit

Multistandard rectified power supply circuit with power factor

A bipolar integrated circuit with N-type wells (2) formed in a P-type substrate (1) includes in first wells, first transistors (EBC), the well of which constitutes the collector. P-type base region (7a) is formed in the first well with an N+ emitter region (8) formed in the base region. In at least a second well forming a collector, a composite second transistor (E'B'C') is constituted by an elemental third transistor (E.sub.1 B.sub.1 C') comprising regions of the same doping level as the first transistor and an elemental fourth transistor (E.sub.2 B.sub.2 C') having a base region (11) with a high doping level with respect to that of the bases of the first transistor. Emitter regions (8b, 12) of the elemental transistors are of the same doping level as that of the first transistors. The emitters and bases of the third and fourth elementary transistors are interconnected and constitute the emitter and the base of the composite second transistor.

Transistor with a predetermined current gain in a bipolar integrated

An avalanche diode is formed in an N layer (20) of a bipolar integrated circuit. The diode comprises a first (P) region (22) and N region (21) disposed inside the first region. The portion of the first region which resides under the N region and close to the interface with the latter has a first doping level. A second (P) region (23) extends under the N region with a second doping level higher than the first close to the junction. A third P region (30) is disposed under the N region and overlaps the second P region. The third region has, at its interface with the N region, a doping level intermediate the first and second doping levels.

Avalanche diode in a bipolar integrated circuit

A compensated temperature distance detector wherein the detecting coil is realized in the form of wires, divided and isolated the one from the others. A first set of wires (L) constitutes the oscillating coil parallel connected to a capacitor and fed between two distinct voltages (VCC and M) through a current source (IB) and a second set of wires (L'), connected at a first extremity to a first set of wires and to a generator, is connected at its other extremity to a third voltage (V1), whereby a d.c. current flows through the series connection of the first and second sets of wires.

Temperature compensated method and apparatus for detecting the

A bipolar power switch (4) in series with the primary of an ignition coil (2) and a detection resistor (R1) associated with a voltage divider (R2, R3) supplying a voltage V.sub.D ; a controlled amplifier-comparator (9), the first input of which receives the measured voltage and the second input receives a reference voltage (8), and the output of which is connected with the base of the switch (4), this amplifier-comparator acting for limiting the base current when the measured voltage is approaching the reference voltage; a series resistor (R10) between the output of the amplifier-comparator (9) and the base of the switch (4); and a differential amplifier (11), the inputs of which are connected with the terminals of the series resistor and the output of which is connected with the first input of the amplifier-comparator.

Ignition control circuit

The invention relates to an angular measurement device comprising a variable reluctance magnetic circuit comprising a fixed portion (3) associated with a coil (2) and at least a moving element (4) attached to a part (5) rotating in front of the fixed portion, the angular position of which is to be detected, comprising: means (I) for integrating the voltage across the coil, means for measuring the instantaneous value of the integrated voltage (15), means for comparing this measure to a calibrating curve of the integrated voltage versus the angle.

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Grenoble, France

Jean-Michel Moreau