Stmicroelectronics S.a.

Stmicroelectronics International N.v.

Jean-Marie Permezel

Gilles Troussel

Jerome Nebon

Jean-Raphaël Bezal

Eric Benoit

A device includes a matrix of active pixels, with each active pixel having an OLED diode having a cathode to receive a cathode voltage, and a control circuit coupled to an anode of the OLED diode. The device also includes at least one dummy pixel having a dummy OLED diode having a cathode to receive the cathode voltage, and an anode, and a dummy control circuit coupled to the anode of the OLED diode and having a power supply terminal. The dummy OLED diode and the dummy control circuit are substantially similar to the OLED diode and the control circuit. First regulation circuitry is configured to deliver a reference current to the power supply terminal to thereby generate a voltage, and second regulation circuitry is configured to regulate the cathode voltage so as to maintain the voltage at the power supply terminal at a given level.

Device with OLED matrix of active pixels with cathode voltage regulation, and corresponding method

A device includes an OLED pixel and a control circuit controlled at a refresh rate thereof. The device includes first and second dummy control circuits having similar operating characteristics to the control circuit. A controller and logic circuit switch on the first and second dummy control circuits and apply an input voltage so the first and second dummy control circuits output first and second output voltages. At a first time, the controller and logic circuit switch off the second dummy control circuit so a leakage current flows through the second dummy control circuit to ground, causing the second output voltage to reduce. Comparison circuitry determines a second time at which, due to the reduction of the second output voltage, a difference between the first and second output voltages is greater than a threshold. Determination circuitry determines the refresh frequency based upon elapsed time between the first and second times.

Method for determining a refresh frequency for a matrix of OLED active pixels and corresponding device

A control device for a matrix plasma display screen has a row driver circuit capable of sequentially selecting the rows of the matrix and a column driver circuit, for each column of the matrix, with an individual column driver unit that has at least a first transistor of the MOS type capable of emitting, towards each column of a desired set of columns, a state change signal in order to allow the transition of the set from a first state towards a second state, and a controller. The first transistor is capable of emitting state change signals that have a state that is transitional from a low state towards a high state; the controller has a control transistor with one electrode directly connected to the power supply terminal and another electrode capable of delivering a control voltage to the control electrode of the first transistor, so as to limit the value of the current flowing through the first transistor in the course of the transitional state, in such a manner as to regulate the rise time of the state change signal.

Method and device for controlling a matrix plasma display screen

A method and circuit to control of a circuit for addressing at least one line electrode of a plasma display panel having, for each line, a line selection stage formed of two switches in series between two input terminals of the selection stage, the method including use of a first one of the two switches of the selection stage of each line to flow a current from or to an inductive element of the addressing circuit.

Plasma display panel control circuit

A high-potential output stage includes an output circuit to power a load with a variable high potential when it receives a low-level active input logic signal. It also includes a driving circuit which produces a high-level control logic signal as a function of the input logic signal to drive the output circuit which is powered by a DC high potential. The output stage also synchronizes the input logic signal with variations of the variable high potential.

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Grenoble, France

Jean-Marie Permezel