Study of efficacy in a mercury-free flat discharge fluorescent lamp using a zero-dimensional positive column model

Mercury discharge lamps are often used because of their high efficiency; however, the usage of mercury lamps will be restricted or forbidden for safety and environmental purposes. Finding alternative solutions to suppress mercury is of major interest. The aim of this work is to increase the luminous efficacy of a commercial-free mercury flat dielectric barrier discharge lamp (Planilum, St Gobain) in order to reach the necessary conditions for the lamp to be used as a daily lighting source. The lamp is made of two glass plates separated by a gap of 2 mm. The gap is filled by a neon xenon mixture. The external electrodes made of transparent ITO (indium tin oxide) are deposited on the lamp glass plates. The electrical signal applied to the electrodes generates a UV-emitting plasma inside the gap. Phosphors deposited on the glass allow the production of visible light. The original electrode geometry is plane-to-plane; this induces filamentary discharges. We show that changing the plane-to-plane geometry to a coplanar geometry allows the plasma to spread all over the electrode surface, and we can reach twice the efficacy of the lamp (32 lm/W) as compared to the original value. Using this new electrode geometrical configuration and changing the electrical signal from sinusoidal to a pulsed signal greatly improves the visual uniformity of the emitted light all over the lamp. Electrical and optical parametric measurements were performed to study the lamp characteristics. We show that it is possible to develop a free mercury lamp with an efficacy compatible with lighting purposes.

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“…From Shiga and al. [17][18][19], the duty cycle is an important parameter on the efficacy and the consumed power. For a fixed pressure:…”

Section: Optimizations Studies: Efficacy Vs (Pressure Frequency Andmentioning

confidence: 99%

Parametric Studies of a Mercury-Free DBD Lamp

Caillier

Therese

Belenguer

et al. 2021

Plasma

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“…12(b) gives the total density of Xe 2 *( 1 R u þ ) and Xe 2 *( 3 R u þ ) during one full sustain pulse. Because Xe 2 *( 1 R u þ ) and Xe 2 *( 3 R u þ ) cannot be stepwise-excited or stepwise-ionized, 18,25,27 these Xe excimer excitation states are proportional to the excimer VUV emission. Therefore, we conclude that with the increase of Xe partial pressure, not only the time averaged excimer VUV intensity is increased but also the peak intensity.…”

Section: B 2d Simulationsmentioning

confidence: 99%

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

Zhu

Zhang

Kajiyama

2012

Journal of Applied Physics

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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.

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“…5 To explain those high values, two main reasons can be given. Moreover, this consumption could be soon doubled as mercury will be banned from CCFL.…”

Section: Interest Of Cnt Based Lcd Backlight Unitmentioning

confidence: 99%

Green backlighting for TV liquid crystal display using carbon nanotubes

Delepierre

Mahfouz

Aires

et al. 2010

Journal of Applied Physics

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Articles you may be interested inHorizontally-aligned carbon nanotubes arrays and their interactions with liquid crystal molecules: Physical characteristics and display applications AIP Advances 2, 012110 (2012); 10.1063/1.3679155Fully sealed carbon nanotube flat-panel light source and its application as thin film transistor-liquid-crystal display backlight A methodology to evaluate the emission characteristics of carbon nanotube layers in the context of liquid crystal display backlighting has been elaborated. Carbon nanotube layers with emission characteristics compatible with backlighting have been demonstrated for growth temperature as low as 400°C, thanks to the use of plasma pretreatment before growth. This very low growth temperature allows to use soda lime glass for the backlight unit and thus to expect very low cost and very low power consumption devices with this technology.

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Study of efficacy in a mercury-free flat discharge fluorescent lamp using a zero-dimensional positive column model

Cited by 31 publications

References 27 publications

Parametric Studies of a Mercury-Free DBD Lamp

Parametric Studies of a Mercury-Free DBD Lamp

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

Green backlighting for TV liquid crystal display using carbon nanotubes

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