Discharge efficiency in plasma displays

Ferroelectrets (i.e., charged cellular polymers) are rendered piezoelectric by means of barrier discharges inside the air-filled voids. The light emission from barrier discharges in cellular polypropylene ferroelectrets was quantitatively studied. Light emission typically occurs above a threshold voltage of 3 kV and then significantly increases with the applied voltage. Time-resolved images reveal discharge processes in individual voids. In addition, a second "back discharge" emission is observed when the voltage is reduced to zero. The buildup of the "effective polarization" in cellular PP ferroelectrets was studied by an acoustic method and dielectric resonance spectroscopy. A polarization-voltage (P-V) hysteresis loop was obtained by analyzing the data with an existing model for the piezoelectric d33 coefficient of ferroelectrets, from which a threshold charging voltage of 3 kV and the back barrier discharges were confirmed and a zero-field "effective polarization" o f 0.5 mC/ m2 was determined. However, charge densities of up to 2 mC/ m2 were measured under an applied bias voltage, leading to the conclusion that the observed back discharges destroy a significant fraction of the effective charge density

Section: Introductionmentioning

confidence: 99%

Barrier discharges in cellular polypropylene ferroelectrets: How do they influence the electromechanical properties?

Qiu¹,

Mellinger²,

Wegener³

et al. 2007

“…Recently, it was reported that PDPs with high-Xe-content gas mixtures have the potential for improving luminous efficiency under a conventionally used driving scheme. 11,12 The luminous efficiency exhibits a step-wise increase by increasing the sustain voltages especially for higher-Xe contents. The luminous efficiency increases linearly to total pressure.…”

Section: Introductionmentioning

confidence: 99%

Discharge efficiency in high-Xe-content plasma display panels

Hayashi

Heusler

Hagelaar

et al. 2004

We study theoretically the overall output performance and the dominating reaction processes of the vacuum ultraviolet ͑UV͒ radiation production in high-Xe partial pressures in plasma display panels ͑PDPs͒ with Ne-Xe gas mixtures. A two-dimensional self-consistent fluid model is applied for the simulations of discharges and UV radiation in sustaining phases of PDPs. The UV intensity increases with the Xe partial pressure ( P Xe ). The discharge efficiency also increases with P Xe . The resonant radiation from Xe( 3 P 1 ) dominates for 3.5%, while that from Xe 2 ( 3 ⌺ u ϩ ) becomes dominant over Xe( 3 P 1 ) for 10%-30%. Remarkably for 30%, the intensity from Xe 2 ( 1 ⌺ u ϩ ) is even larger than that from Xe( 3 P 1 ). It is found that for higher P Xe , the UV radiation mainly consists of the excimer radiation from Xe 2 ( 1 ⌺ u ϩ ) and Xe 2 ( 3 ⌺ u ϩ ). Here, Xe( 3 P 1 ) does not play a role itself as the UV radiator of the resonant radiation ͑147 nm͒, but as the precursor to Xe 2 ( 1 ⌺ u ϩ ), which results in the excimer radiation ͑173 nm͒.

“…10 shows the most important energy levels and transitions for Xe. The generation of the Xe excitation states Xe*(1s 4 ) and Xe*(1s 5 ) include three kinds of processes: 21,25 (1) electron impact excitation directly from the ground state (shown by the gray arrows); (2) heavy body collisions with Xe**(2p 5-10 ), Xe*(1s 2 ), or Xe*(1s 3 ) by the Ne or Xe atoms (shown by the magenta arrows); (3) radiative processes by Xe**(2p [1][2][3][4] or Xe**(2p 5-10 ) (shown by the green arrows). The processes related to NIR and VUV radiation, which are concerned with in this section, are marked in the diagram.…”

Section: B 2d Simulationsmentioning

confidence: 99%

“…INTRODUCTION Recently, the improvement of luminous efficacy in the PDPs towards the goal of "5 lm/W" is achieved by using various advanced technologies. [1][2][3][4][5][6][7][8] However, comparing with the fluorescent lamp that is able to reach the luminous efficacy of 60 lm/W, the gap in plasma display panel (PDP) is still huge. This becomes especially clear when observing the difference in the VUV production efficiency: compared with the other VUV emitting plasma devices, like the fluorescent lamps, the small discharge space of PDP limits the VUV production efficiency of PDP to a level of only 0.1, compared with about 0.6 for a fluorescent lamp.…”

mentioning

confidence: 99%

Impact of Xe partial pressure on the production of excimer vacuum ultraviolet emission for plasma display panels

Zhu

Zhang

Kajiyama

2012

In this work, the effect of the Xe partial pressure on the excimer vacuum ultraviolet (VUV) emission intensity of the plasma display panels is investigated, both by measuring the spectral emission directly and by two-dimensional simulations. Experimentally, we find that at the high Xe partial pressure levels, there is an supra-linear increase of excimer VUV radiation and that determines the strong increase of luminance at the high pressures and high voltage. Due to the increase of the luminance and the almost unchanged discharge current, the luminous efficacy strongly increases with the Xe partial pressure. In addition, we also investigated the dynamics of the VUV generation, by measuring the decay time of the excimer VUV light as a function of the gas pressure. It is found that the decay time decreases with the increase of gas pressure. The spatial characteristics of the excimer VUV emission are also discussed. Different from the Ne and near-infrared emission, the excimer VUV emission is generated near the surface of the electrodes and increases uniformly on both sides of the anode and cathode (i.e., the bulk plasma region). Most importantly, it is found that the VUV production occurs during the afterglow period, while it is almost zero at the moment of the discharge itself. From the simulations, it can be seen that the Xe2*(3Σu+) excimer species, which are generated from Xe*(1s5), play a dominant role in the excimer VUV emission output at the high Xe partial pressure. The two-dimensional simulations also show that the strong increase of Xe excimer excitation states in the case of high pressure is mainly the result of the high conversion efficiency of the Xe excimer states, especially in the afterglow period. Due to the high conversion efficiency of Xe excitation species to Xe excimer species by the high collision rate in the case of high pressure, there is a strong increase of excimer VUV production, especially from the cathode.