Stmicroelectronics S.a.

Sgs-thomson Microelectronics S.a.

Danika Chaussy

Céline Mas

Michel Barou

Eric Benoit

Philippe Maige

Olivier Le Briz

Marius Reffay

Olivier Scouarnec

Eric Cirot

A circuit for controlling a matrix display formed of light-emitting diodes, capable of successively selecting lines of the screen and, for each line from a set of selected lines, of selecting columns, the voltage of each selected column settling at an operating voltage. The circuit is capable, before selection of each line from said set of lines, of precharging at least the columns to be selected to a precharge voltage. The circuit includes a device for adjusting the precharge voltage including a measurement circuit capable, on each selection of a line from said set of lines, of measuring the maximum operating voltage from among the operating voltages of the selected columns; a circuit capable of storing the maximum measured operating voltage; and a circuit capable of adjusting the precharge voltage based on the maximum stored operating voltage.

Automatic adaptation of the precharge voltage of an electroluminescent display

Circuitry for controlling a display matrix formed of light-emitting diodes arranged in rows and columns, diodes in each row being connected to common row lines, and diodes in each column being connected to common column lines, each of the column lines being selectively connected to a current source for providing a current to each of the column lines when the column line is selected, a column voltage being present at a column node of each column line while the column line is selected, each of the row lines being selectively connected to a rowoff voltage for turning off the diodes in that row, the circuitry including circuitry for generating the rowoff voltage including: capture circuitry arranged to capture a maximum value of the column voltages present at the column nodes of a plurality of selected column lines; storage circuitry arranged to store the maximum column voltage; and output circuitry arranged to provide the rowoff voltage based on the maximum column voltage.

Optimized rowoff voltage

A device for regulating the bias voltage of circuits for controlling columns of a matrix display capable of selecting columns to turn on the light-emitting diodes of the selected columns and of a selected line, the device including a first measurement circuit providing a first measurement signal representative of the highest voltage among the voltages of the selected columns; a second measurement circuit providing a second measurement signal representative of the lowest voltage among the voltages of the selected columns; and an adjustment circuit receiving the first and second measurement signals and capable of decreasing the bias voltage if the first measurement signal is smaller than a first comparison signal and of increasing the bias voltage if the second measurement signal is greater than a second comparison signal.

Automatic adaptation of the supply voltage of an electroluminescent display according to the desired luminance

A method for regulating the biasing voltage of column control circuits of an array screen formed of LEDs distributed in lines and columns, the column control circuits being adapted to turning on at least one LED of a line. The method includes increasing the biasing voltage when the current flowing through at least one activated LED is smaller than a determined luminance current and of decreasing the biasing voltage when the current flowing through each activated LED is equal to the determined luminance current.

Automated adaptation of the supply voltage of a light-emitting display according to the desired luminance

A device for producing a video image sharpness improvement signal (DOC-DOC), with black level clipping of an associated video signal, comprises a differential transconductance stage processing the video signal and whose bias currents (Imax) are directly proportional to the active component (&#x394;V) of the video signal so as to bring about a black level sharpness improvement signal clipping.

Device for generating a video image sharpness improvement signal

A preamplifier includes an output stage having a bandwidth which is adjustable by a control signal. The output stage includes an amplifier with an adjustable bandwidth. The amplifier includes a main input for receiving an input current, a main output for providing an output voltage, a resistor connected between the main input and output. A current amplifier with an adjustable gain is connected for receiving the input current. A capacitor is connected between an output of the current amplifier and the main output. An inverting transconductance circuit is connected between the output of the current amplifier and the main output.

Preamplifier with an adjustable bandwidth

The present invention relates to a method for correction of the horizontal scanning current of a cathode-ray tube based on a modulation of this scanning current by a substantially parabolic signal at the image frame frequency, obtained by a squaring of a current ramp, including inflecting the ends of this current ramp before its squaring.

Horizontal deviation correction circuit and method for a television set

The present invention relates to a power amplifier having an output stage in MOS technology, including an upper half-output stage comprised of two P-channel MOS power transistors mounted as a current mirror, a lower half-output stage comprised of two N-channel MOS power transistors mounted as a current mirror, an output terminal of the amplifier corresponding to the common drains of a first MOS transistor of the upper stage and of a first MOS transistor of the lower stage, and a control stage in bipolar technology for setting, according to a control voltage, two control currents of the half-output stages.

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Brie et Angonnes, France

Danika Chaussy