Stmicroelectronics International N.v.

Jerome Nebon

Jean-Marie Permezel

Christophe Forel

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 device includes a matrix of active pixels. Each active pixel includes an OLED and a control circuit configured to refresh the active pixel and including at least one transistor having a first conduction terminal coupled to a supply line and a second conduction terminal coupled to the OLED. Supply circuitry is configured to apply a supply voltage to the supply line of each active pixel during the refreshing of the active pixel and for a time period less than a duration of the refreshing of the active pixel.

Device comprising a matrix of active OLED pixels with brightness adjustment, and corresponding method

An integrated device includes a semiconducting substrate having a matrix of active pixels formed therein. Each active pixel includes an OLED diode, a first nMOS transistor having its source coupled to an anode of the OLED diode, and a refresh circuit coupled to a gate of the first nMOS transistor. The first nMOS transistor has its source and its substrate coupled together. The first nMOS transistor is situated in and on a first part of the semiconductor substrate, and the refresh circuit is situated in and on a second part of the semiconductor substrate, with the first part and the second part being electrically insulated from one another.

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Seyssins, France

Jerome Nebon