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Lherm, France

Buso D.,CNRS LAPLACE Lab | Bhosle S.,OLISCIE | Liu Y.,Fudan University | Ternisien M.,CNRS LAPLACE Lab | And 2 more authors.
IEEE Transactions on Industry Applications

In this paper, a hardware equivalent of an organic light-emitting diode (OLED) was designed and investigated. This substitution OLED device is based on a circuit-equivalent OLED model and can be used to design and test OLED dedicated drivers. Indeed, OLEDs are available on the market, but they are still very expensive and hard to obtain. Compared to a real OLED, the substitution device is cheap and robust and can be easily duplicated. Moreover, a photodetector is not required to measure the light output waveform. This can be simply done by measuring a voltage across a resistance. This model can be used, for instance, to simulate a large OLED panel made of several associated single OLEDs for various series/parallel connection strategies. It can also be used to simulate aging phenomena by changing the values of some of its components. This might be useful for the definition of strategies to compensate aging effects like luminous flux depreciation. Another advantage of such a device is its use for power supply tests as it could serve as a substitution load, at maximum deviation from standard OLED electrical characteristics. We discuss the theoretical model that was used as a basis for developing the device. The accuracy of the model was then evaluated, particularly in pulsewidth-modulation dimming conditions. Then, the hardware equivalent device was compared to a real OLED. Finally, an example of the potential use of this substitution device is given: It was successfully used to investigate the "overdrive" technique in order to increase OLED light output rise time. This technique improves the light output rise time by a factor of over 4. © 1972-2012 IEEE. Source

Piquet H.,National Polytechnic Institute of Toulouse | Bhosle S.,OLISCIE | Diez R.,Pontifical Xavierian University | Cousineau M.,National Polytechnic Institute of Toulouse | And 4 more authors.
Quantum Electronics

The efficiency of the electrical power transfer to the gas mixture of a XeCl dielectric barrier discharge (DBD) exciplex lamp is analysed. An equivalent circuit model of the DBD is considered. It is shown that the excilamp power can be controlled by applying current to the lamp. This highly desired property is ensured by means of a specific power supply topology, whose concepts and design are discussed. The experimental prototype of a current-mode converter operating in the pulsed regime at pulse repetition rate of 50 kHz is presented and its capability to control the amount of energy transferred during each current pulse is demonstrated. The capability of this power supply to maintain specific operating conditions for the DBD lamp, with a very stable behaviour (even at a very low current, in the regime of a single discharge channel), is illustrated. The experimental results of a combined use of this converter and a XeCl excilamp are presented. The influence of the supply parameters on the 308-nm XeCl excilamp is analysed. The shape of the UV pulse of the lamp is experimentally shown to be similar to that of the current, which actually flows into the gas mixture. The UV radiation power is demonstrated to be tightly correlated to the current injected into the gas and controlled by the available degrees of freedom offered by the power supply. The measured UV output characteristics and performance of the system are discussed. Time resolved UV imaging of a XeCl DBD excilamp is used to analyse the mechanisms involved in the production of exciplexes at various power supply regimes. It is shown that a pulsed voltage source leads to formation of short high intensity UV peaks, while current pulses lead to formation of sustained discharge filaments. Based on the results of modelling of the above-mentioned operation conditions, the two power supply regimes are compared and analysed from the point of view of the UV power and radiative control. © 2012 Kvantovaya Elektronika and Turpion Ltd. Source

Le T.D.,University Paul Sabatier | Bhosle S.,OLISCIE | Zissis G.,University Paul Sabatier | Piquet H.,University Paul Sabatier
Conference Record - IAS Annual Meeting (IEEE Industry Applications Society)

A XeCl dielectric barrier discharge under applied pulsed and sinusoidal voltage waveforms is simulated using a one dimensional drift diffusion model. In both waveforms, the light output depends not only on the gas mixture composition but also on the electrical parameters of the voltage waveform such as the frequency, the duty ratio...ctc. At the same amplitude of the voltage and the frequency, the UV output efficiency of the pulsed voltage is higher than the one of sine voltage. These results obtained in this paper allow to find out an appropriate power supply mode for a DBD excilamp. © 2011 IEEE. Source

Blanco Viejo C.,University of Oviedo | Anton J.C.A.,University of Oviedo | Robles A.,University of Oviedo | Ferrero Martin F.,University of Oviedo | And 3 more authors.
IEEE Transactions on Industry Applications

Discharge lamp models based on dynamic lamp conductance are derived from physical equations that describe lamp behavior. Lamp constructive data are not necessary to build the models, just the lamp current and voltage data are necessary. In addition, these models have a relatively low complexity, and not much calculation time is necessary to obtain them. They can be used to simulate low- and high-pressure lamps at low and high (20kHz < f < 1MHz) frequencies. Two of these models, derived from different physical equations, are tested and compared using fluorescent and high-pressure sodium lamps. © 2011 IEEE. Source

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