Mercury-free Flat Fluorescent Lamp Research Articles

The Effects of Electrode Configuration on the Luminance and Luminous Efficacy of Mercury-Free Flat Fluorescent Lamp

To obtain highly efficient and stable discharges in mercury-free flat fluorescent lamps (MFFLs), the effects of the main electrode configuration on the electro-optical characteristics such as the operating voltage margin, luminance, and luminous efficacy are investigated. The spatiotemporal characteristic of the infrared emission from discharges in different electrode configurations (conventional coplanar, counter, and combination discharges) is also studied with an intensified charge-coupled device camera to see the differences with the electrode configuration variation. The MFFL having the combination electrode configuration with Ne-30% Xe gas mixture and a total pressure of 13.3 kPa showed high luminance from 3102 to 22 067 cd/m2 and high luminous efficacy from 49 to 93.5 lm/W for the warm white daylight with a color coordinate of (0.36, 0.36).

Progressive dimming method for mercury-free flat fluorescent lamp

A progressive dimming circuit and method for 32 inch mercury-free flat fluorescent lamp (FFL) were presented based on a newly developed FFL, which showed a large operating margin, high luminance and high luminous efficacy in the case of unipolar driving. The proposed dimming circuit is simple in structure and the dimming method is easy to fulfill. The prototype of 32 inch FFL was built and verified. The results show that a progressive dimming can be implemented by pulse density modulation (PDM) method or frequency modulation method and the power consumption can be reduced since the light output of FFL can be controlled progressively. A dimming range about 100% to 6% can be achieved by using the proposed method.

High Efficiency Alternating Current Driver for Capacitive Loads Using a Current-Balance Transformer

This paper proposes a new alternating current driving method for highly capacitive loads such as plasma display panels or piezoelectric actuators, etc. In the proposed scheme, a current balance transformer, which has two windings with the same turn-ratio, provides not only a resonance inductance for energy recovery but also a current balance among all of the switching devices of the driver for current stress reduction. The smaller conduction loss than conventional circuits occurs due to the dual conduction paths which are parallel each other in the current balance transformer. Also, the leakage inductances of the transformer are utilized as resonant inductors for energy recovery by the series resonance to the capacitive load. Furthermore, the resonance contributes to the small switching losses of the switching devices by soft-switching operation. To confirm the validity of the proposed circuit, prototype hardware with a 12-inch mercury-free flat fluorescent lamp is implemented. The experimental results are compared with a conventional energy-recovery circuit from the perspective of luminance performances.

High‐luminance and luminous‐efficacy mercury‐free flat fluorescent lamp (MFFL) with local‐dimming functionality

Abstract— In order to realize high‐luminance and luminous‐efficacy mercury‐free flat fluorescent lamps (MFFLs) for LCD backlighting, the phosphor profile was optimized to enlarge the surface area. The proposed uneven profile of the rear phosphor increases the effective surface area of the phosphor, resulting in a wide luminance range from 3000 to 16,788 cd/m2 with a corresponding high luminous efficacy from 66 to 34.7 lm/W, respectively. Also, a dynamic operation method for an adaptive local‐dimming and scanning operation is proposed which can be used in a 32‐in. multi‐structured configuration having one inverter system. With the deployment of the bipolar drive scheme and dual auxiliary electrodes, a stable and selective diffuse glow discharge with high luminance is possible.

Luminescence characteristics of mercury-free flat fluorescent lamp with arc-shape anodes

The luminescence characteristics of mercury-free flat fluorescent lamp (FFL) with arc-shape anodes utilizing dielectric barrier discharge were investigated by comparing its luminance uniformity with that of the conventional FFL with beeline-shape anodes and measuring the variation of its luminance and luminous efficacy with discharge gap, dielectric thickness, xenon concentration and total gas pressure of mixture gas. The experimental results show that the steady diffusive micro-discharge can be obtained at a high gas pressure even near to 1 atmosphere pressure when the narrow pulse-width voltage waveform is applied, and the luminance and luminous efficacy can both be improved with the increase of discharge gap, whereas the luminous efficacy rises and gradually reaches to a saturation value with the increase of dielectric thickness. Under the driving pulse with frequency of 65kHz and peak voltage of 2.2kV, the novel FFLs with a diagonal size of 12 inches demonstrate the luminance of over 6400cd/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , luminous efficacy of over 22lm/w, and luminance uniformity of over 86%.

Luminance and Luminous Efficacy Improvement of Mercury-Free Flat Fluorescent Lamp With Arclike Electrode

A mercury-free flat fluorescent lamp with an arclike electrode is developed to improve luminance and luminous efficacy and to prevent discharge contraction. The influences of the rising time of a driving waveform and the gas mixture under different gas pressures on luminance and luminous efficacy are studied. The experimental results show that the luminance and luminous efficacy increase as the gas pressure and Xe content increase. The luminance of about 7500 cd/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> can be achieved at a pressure of 60 kPa with Ne-Xe (30%). The maximum luminous efficacy of the system, including the inverter, is about 23.7 lm/W at a pressure of 50 kPa with Ne-Xe (30%). Compared with the gas mixture of Ne-Xe (30%), when the gas mixture of Ne-Xe (32%)-He (8%) is used, the luminance and ignition voltage increase. In addition, the luminous efficacy for a steep rising edge of a waveform within 400 ns can be increased about 10% higher than that for a gradual rising edge above 800 ns.

Adaptive Local Dimming Lighting of Mercury-Free Flat Fluorescent Lamp Using Dual Auxiliary Electrode

A new drive method designed for the adaptive local dimming lighting of a multistructured 32-in diagonal-sized mercury-free flat fluorescent lamp (MFFL) which consists of a matrix array of 10 × 16 60-mm diagonal-sized unit cells is proposed. The adoption of the dual auxiliary electrode and the bipolar-pulse drive scheme resulted in a wide stable operating voltage margin at low driving voltages. The cell turn-on or turn-off selectivity can be obtained through the change of the connection state of the dual electrode. Using the proposed MFFL with the dual auxiliary electrode as a data electrode and the subfield method, a new drive scheme for a 2-b adaptive local dimming control of 10 × 16 lamp array with one inverter system is proposed and demonstrated.

Electro-optic characteristics and areal selective dimming method for a new highly efficient mercury-free flat fluorescent lamp (MFFL)

A highly efficient mercury-free flat fluorescent lamp (MFFL) with dielectric barrier Xe gas discharge was developed for a LCD-TV backlight source. The unit cell of the lamp has a simple structure with two main electrodes running parallel to each other and an auxiliary electrode. The adoption of the auxiliary electrode resulted in a wide, stable operating voltage margin, high luminance and efficiency. The 4 inch diagonal size lamp showed a luminous efficacy of 44 lm W−1 at a luminance of 3400 cd m−2 with Ne–Xe(18%) gas mixture. We demonstrated that the 4 inch unit cell can be used to construct a 5 × 8 multi-structured lamp of 32 inch diagonal size for application in a large-sized LCD backlight source by a simple repeat of the unit cell. Despite the increase in size, the 32 inch lamp showed the same discharge voltage and margin of the 4 inch unit cell. Using the proposed MFFL with the auxiliary electrode as the data electrode and the subfield method, we developed a driving scheme for 2-bit areal selective dimming control of an M × N multi-cell lamp which can be operated using only one inverter.

P‐98: Current‐Sourced Push‐Pull Inverter for Mercury‐Free Flat Fluorescent Lamp Driving

AbstractThis paper proposes a current‐fed push‐pull inverter for Mercury‐free Flat Fluorescent Lamp (MFFL) Driving. The current‐driving scheme has advantages such as simple circuit, small part count and stable driving operation. The proposed approach is verified by hardware experiments, and compared with a conventional voltage‐sourced driver in perspective of circuit configuration and luminous performances.

Discharge Characteristics of a Mercury Free Flat Fluorescent Lamp Without the Dielectric Layers

We developed a mercury free Flat Fluorescent Lamp (FFL) with a high luminance by using the same discharge mode as PDP. Our FFL has the simple structure where the glass substrates are used as the dielectric layer. The panel has a striped line shape of 7-inch diagonal size. The Xe-Ne-He mixture gas was used to generate the plasma, and the gas discharge characteristics under both total gas pressure and partial gas pressure were investigated. The panel showed a maximum high luminance 7,270 cd/m2 under biasing 20 kHz pulse of 3 kV.

Improvement of luminous efficiency in a mercury-free flat fluorescent lamp (FFL) by using fluid simulation

Improvement of luminous efficiency in a mercury-free flat fluorescent lamp (FFL) by using fluid simulation

38.2: The Electro-Optic Characteristics of MFFL (Mercury-Free Flat Fluorescent Lamp) for LCD Backlighting

In this work, we have studied the electro-optic characteristics of multi-cell structured, highly efficient Mercury-free Flat Fluorescent Lamp (MFFL). It was found that each cell of the newly suggested multi-cell structured MFFL could be operated independently by the pulse amplitude modulation, and/or pulse width and/or frequency modulation method which can be utilized to make a back light source for LCD with an areal dimming capability. A wide driving voltage margin of stable glow enabled to have a large luminance variation which resulted in the dimming ratio of 14%, while the frequency and the pulse width modulation resulted in the dimming ratio of 25 and 31% respectively. The interconnection of multi-cell structured MFFL for the full size LCD together with its driving wave form for the independent operation of each cell with a 4 bit sub-field method and its consequent 16 level lighting for each TV field are suggested.

Effect of helium addition on discharge characteristics in a flat fluorescent lamp

The discharge characteristics of a multielectrode dual coplanar in a mercury-free flat fluorescent lamp were investigated using brightness-efficiency measurement and the infrared (IR) spectrum and intensified charge coupled device (ICCD) characteristics. The level of brightness was above 14900cd∕m2 under the conditions of neon-–50% xenon–8% He gas composition, 150Torr pressure, and 20kHz alternating current pulse. The ICCD results revealed a faster and wider discharge with a Ne–50% Xe–8% He gas composition. The effect of adding helium (He) to Ne–50% Xe revealed a faster peak emission, as confirmed by ICCD images. From the gated IR emission spectrum, the intensity ratio of I823nm∕I828nm was ∼8% higher with Ne–50% Xe–8% He than with Ne–50% Xe under the same pressure and applied voltage conditions.

Characteristics of Mercury-Free Flat Fluorescent Lamp

Characteristics of Mercury-Free Flat Fluorescent Lamp

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

A zero-dimensional model of the positive column in Ar/Ne/Xe gas mixtures has been developed to help understand the measured dependence of the efficacy on operating conditions in a mercury-free flat fluorescent lamp in a dielectric barrier geometry. The experimental conditions are such that the radiation from the discharge is homogeneous over most of the discharge voltage. The model uses as input the discharge current waveform from the experiments, and it yields the time variations of the mean electron energy and the species densities. From these quantities we calculate the number of vacuum ultraviolet (VUV) photons emitted by the xenon resonance atoms and excimers during one current pulse and the efficiency for generation of VUV radiation in the positive column, which are compared with the measured luminance and efficacy for various voltages, pulse intervals, and lamp sizes. Over the range of conditions studied, we find that most electrical energy dissipated in xenon excitation is converted to VUV radiation; i.e. the losses of xenon excitation in stepwise and associative ionization processes are small. When the mean electron energy is low, energy dissipation in elastic momentum transfer collisions leads to a decrease in the efficiency. On the other hand, ionization and excitation of argon degrade the efficiency when the mean electron energy is high. To a lesser extent, stepwise excitation of the xenon metastables also decreases the efficiency for high current densities.

水銀レス平面蛍光ランプの特性検討

水銀レス平面蛍光ランプの特性検討

Mercury‐free 18‐in. flat fluorescent lamp with good uniformity

Abstract— We have developed an 18‐in. 287 × 359‐mm mercury‐free flat fluorescent lamp (FFL) having a new structure that utilizes dielectric barrier discharge and contains pure xenon gas. The electro‐optical characteristics have been analyzed. The surface luminance of the lamp having a diffuser sheet is 5600 cd/m2 and the luminance uniformity is 92% at an applied voltage of 1050 Vrms and an applied frequency of 20 kHz in the form of a sine wave.

Design of Electrode for Mercury-Free Flat Fluorescent Lamp

Design of Electrode for Mercury-Free Flat Fluorescent Lamp