Abstract: The general field of the invention is that of the display devices that comprise an active liquid crystal matrix of twisted nematic type. The matrix comprises a set of pixels, a set of rows and of columns and an electronic control device. Each pixel is controlled by a transistor. The voltage applied to each control row is either a switch-on voltage VG_on sufficient to switch on the transistors, or a switch-off voltage VG_off sufficient to switch off the transistors. The voltage applied GMA to each column is dependent on the predetermined optical transmission of the pixel. The display device comprises means for detecting the correct operation of the electronic control device. In case of detection of incorrect operation, the display device comprises cut-off means arranged to force to zero the switch-off voltages VG_off of the rows and the GMA voltages of the columns, so that the transmission of all the pixels of the first set is minimum.

Abstract: The general field of the invention is that of display devices including a liquid-crystal matrix screen composed of elementary pixels, said screen including at least a first electrode used as voltage reference and called the “backplane,” a second electrode in the form of a matrix electronic network delivering the drive voltages for controlling the pixels and control electronics for said electrodes, said screen being used in the so-called “normally black” mode, that is to say that in the absence of applied voltages, the optical transmission of the pixels is substantially zero. In the device according to the invention, the “backplane” drive voltage is a variable periodic voltage, the amplitude of variation of this voltage being sufficient so that in the absence of voltage on the second electrode, the optical transmission of the pixels is sufficient to be detected by an observer.

Abstract: The general field of the invention is that of the display devices that comprise an active liquid crystal matrix of twisted nematic type. The matrix comprises a set of pixels, a set of rows and of columns and an electronic control device. Each pixel is controlled by a transistor. The voltage applied to each control row is either a switch-on voltage VG_on sufficient to switch on the transistors, or a switch-off voltage VG_off sufficient to switch off the transistors. The voltage applied GMA to each column is dependent on the predetermined optical transmission of the pixel. The display device comprises means for detecting the correct operation of the electronic control device. In case of detection of incorrect operation, the display device comprises cut-off means arranged to force to zero the switch-off voltages VG_off of the rows and the GMA voltages of the columns, so that the transmission of all the pixels of the first set is minimum.

Abstract: The invention relates to lighting devices with light-emitting diodes organized in ramps arranged in parallel, each ramp including a certain quantity of light-emitting diodes arranged in series, the ramps being powered by a DC voltage of several tens of volts, called high voltage, the high voltage being generated by a step-up converter circuit from a low DC voltage of a few volts. The value of the voltage is controlled by the duty cycle of the step-up converter circuit, and the voltage is servocontrolled to a constant average value by a servocontrol device controlling the duty cycle. Each servocontrol device has several operating modes defined by a particular electronic addressing of the high voltage or by a defined number of ramps of lit diodes.

Abstract: The general field of the invention is that of display devices comprising a liquid-crystal matrix screen composed of elementary pixels, said screen comprising at least a first electrode used as voltage reference and called the “backplane”, a second electrode in the form of a matrix electronic network delivering the drive voltages for controlling the pixels and control electronics for said electrodes, said screen being used in the so-called “normally black” mode, that is to say that in the absence of applied voltages, the optical transmission of the pixels is substantially zero. In the device according to the invention, the “backplane” drive voltage is a variable periodic voltage, the amplitude of variation of this voltage being sufficient so that in the absence of voltage on the second electrode, the optical transmission of the pixels is sufficient to be detected by an observer.

Abstract: The technical field of the invention is that of secure display devices. The latter comprise at least one matrix screen, electronics for controlling the screen, a fault-detection circuit and electronic means for managing the display device, the screen consisting of pixels placed in lines and in columns, the lines of pixels being controlled by an electronic “drivers” card comprising electronic means arranged so as to generate a first electronic signal representative of the correct or incorrect operation of the said electronic “drivers” card, the fault-detection circuit arranged so as to generate, from the first signal, a second signal processed by the electronic means for managing the display device.