Flat Lamp Research Articles

13.1: A High Resolution 5 Megapixel LCD Monitor for Medical Applications with Mercury‐Free Flat Panel Lamp Backlighting PLANON®

AbstractThe successful design of the first high resolution 5 megapixel monitor for medical application utilizing the mercury‐free PLANON® Lamp as a Backlight will be described. The key advantages of the presented system arise from the fact that the flat panel lamp is mercury‐free and the approach for the implementation. This first flat‐panel lamp based series product ever comes with a unique combination of features like the extraordinary long lifetime, instant start capability and customized color coordinates. A brief description of the design‐in process of the new B/L‐unit into the LCD display is presented. The combination of the high resolution panel with the customized, high performance backlight unit and the intelligent driver electronics yields advantages in the areas of lifetime, power savings, stability and calibration.

Discharge Characteristics of Xe Plasma Falt Lamp for LCD Backlight According to Operating Voltage Pulse

Conventional backlight for liquid crystal display (LCD) uses mercury which leads to environmental pollution. In this study, characteristics of AC coplanar type mercury-free plasma flat lamp have been studied. Pollution-free Xe-He is adopted as a discharge gas system. Since the Xe gas has a lower efficiency in generating vacuum ultraviolet (VUV) than mercury, the improvement of luminance and luminous efficiency in the Xe gas system is very important. The electrode, dielectric, and phosphor layers constituting lamp are formed on the bottom glass by the screen printing method. The effects of pulse shape, on-time, and pulse frequency on the luminance and luminous efficiency have been examined. For Xe(5%)-He gas, the lamp exhibits higher efficiency with sharper pulse shape, higher peak voltage, and shorter pulse on-time (up to 2 ). Higher efficiency and lower consumption of power were obtained at 30 kHz than at 60 kHz. The collision of ion to bottom electrodes is a dominant factor to raise the lamp temperature. Therefore the high voltage and low current discharge system is necessary for reduction of the lamp temperature as well as for enhancement of the luminous efficiency.

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.

Improvement of luminance efficiency in xenon dielectric barrier discharge flat lamp

In this work, to improve the luminance efficiency of the lamp, xenon dielectric barrier discharge flat lamps (DFLs) with new electrode structures were fabricated and electric-optical characteristics were analyzed in respect with various discharge conditions. The luminance efficiency increased as the increasing of the capacitance and the reducing of the dielectric loss, and as the improvement in the transmittance of the generated visible light at the discharge space. The luminance efficiency of the DFL with Al/sub 2/O/sub 3/ dielectric layer of 60-/spl mu/m thickness, matrix shape electrodes and discharge space of 1-mm gap-width was obtained as 26.3 lm/W and the luminance was 4 873 cd/m/sup 2/.

Mercury‐free, high‐luminance and high‐efficacy flat discharge lamp for LCD backlighting

AbstractThe liquid‐crystal displays having a 4‐ to 7‐inch diagonal used in car navigation systems demand strict conditions of at least 10,000 cd/m2 luminance and a –30 to 80 °C operating temperature range for backlights for use in a variety of environments. To satisfy these conditions, a flat discharge lamp that offered high luminance, high efficiency, and a high degree of balance was developed by employing a simple structure that used a rare gas instead of mercury, which has a strong temperature dependence. Narrowing the pulse width of the drive voltage pulse and limiting the amount of current made it possible to obtain uniform emitted light that spreads throughout the entire discharge space. When the maximum luminance of 9200 cd/m2 was obtained, the emission efficiency was 20.4 lm/W. When the luminance was 1080 cd/m2, the maximum emission efficiency of 34.1 lm/W was achieved. © 2001 Scripta Technica, Electron Comm Jpn Pt 2, 84(8): 55–63, 2001

19.1: Invited Paper: Xe Discharge Backlights for LCDs

AbstractMercury‐free, Xe fluorescent lamps are becoming more and more important for LCD backlights, not only from the environmental point of view but for attaining high picture quality. The paper explains underlying limitations assessed to the Xe glow discharges and introduces various Xe backlights with a stress on a flat discharge lamp.

37.3: Mercury‐Free, Simple‐Stuctured Flat Discharge LCD Backlights Ranging from 0.5 to 5.2‐in. Diagonals

AbstractMercury‐free flat discharge lamps with diagonal sizes ranging from 5.0 to 5.2 inches have been developed for LCD backlights. The lamps have simple structures with insulated electrodes. Uniform discharges are obtained by adjusting drive pulse voltage and waveforms. As lamp diagonal becomes larger, luminance and efficacy increa‐se, and the dimming can be varied in wider range.

A 30,000‐cd/m2, 50‐lm/W, and 92%‐luminance‐uniformity flat discharge fluorescent lamp for LCD backlights

Abstract— A 5.2‐in.‐diagonal simple‐structured argon‐mercury cold‐cathode flat discharge fluorescent lamp has been developed for LCD backlighting. A pair of insulated electrodes is provided at the top and bottom ends of the inner surface of the front glass plate. Phosphor is deposited on both the front and rear glass plates. A luminance of 30,000 cd/m2 and a luminous efficacy of 50 lm/W were obtained with a luminance uniformity of 92% without the use of a diffuser sheet. A mechanism for obtaining the high luminous efficacy is described. Luminance can be dimmed down to 4% of the peak value by extending the pulse interval and/or by reducing the pulse amplitude.

34.1: High‐Luminance and High‐Efficacy Electric‐Field‐Coupled Discharge Lamp for 18‐in. Diagonal LCD Backlighting

AbstractA flat lamp is developed for an 18‐in.‐diagonal LCD backlighting, using 8 electric‐field‐coupled discharge tubes. All the tubes can be driven with a single inverter circuit. Luminance, efficacy, and input power are 3500cd/m2, 34 lm/W, and 35W when the lamp is driven at 5.24MHz and 790V.

Parallel operation of microhollow cathode discharges

Parallel operation of DC microhollow cathode discharges in argon at pressures up to several hundred torr was obtained without individual ballast at low currents, where the slope of the current-voltage characteristic is positive. By using semi-insulating silicon as anode material, we were able to extend the range of stable operation over the entire current range, including that with negative differential resistance. This opens the possibility to utilize microhollow cathode discharge arrays in flat panel lamps.

Generation of intense excimer radiation from high-pressure hollow cathode discharges

By reducing the diameter of the cathode opening in a hollow cathode discharge geometry to values on the order of 100 μm, we were able to operate these discharges in noble gases in a direct current mode up to atmospheric pressure. High-pressure discharges in xenon were found to be strong sources of excimer radiation. Highest intensities at a wavelength of 172 nm were obtained at a pressure of 400 Torr. At this pressure, the vacuum ultraviolet (VUV) radiant power of a single discharge operating at a forward voltage of 220 V and currents exceeding 2 mA reaches values between 6% and 9% of the input electrical power. The possibility to form arrays of these discharges allows the generation of flat panel VUV lamps with radiant emittances exceeding 50 W/cm2.

Emission of excimer radiation from direct current, high-pressure hollow cathode discharges

A novel, nonequilibrium, high-pressure, direct current discharge, the microhollow cathode discharge, has been found to be an intense source of xenon and argon excimer radiation peaking at wavelengths of 170 and 130 nm, respectively. In argon discharges with a 100 μm diam hollow cathode, the intensity of the excimer radiation increased by a factor of 5 over the pressure range from 100 to 800 mbar. In xenon discharges, the intensity at 170 nm increased by two orders of magnitude when the pressure was raised from 250 mbar to 1 bar. Sustaining voltages were 200 V for argon and 400 V for xenon discharges, at current levels on the order of mA. The resistive current–voltage characteristics of the microdischarges indicate the possibility to form arrays for direct current, flat panel excimer lamps.

High-pressure hollow cathode discharges

Reducing the diameter of the cathode hole in a plane anode - hollow cathode geometry to m has allowed us to generate direct current discharges in argon at atmospheric pressure. Up to pressure times cathode hole diameter (pD) values of approximately 5 Torr cm, and at sub-mA currents, glow discharges (predischarges) are observed with a shape which is determined by the vacuum electric field. In the same pD range, but at higher currents of up to approximately 4 mA, the discharges are of the hollow cathode discharge type. At pD values exceeding 5 Torr cm the predischarges turn into surface discharges along the mica spacer between the electrodes. At currents > 4 mA filamentary, pulsed discharges are observed. Qualitative information on the electron energy distribution in the microdischarges has been obtained by studying the VUV emission from ionized argon atoms and the argon excimer radiation at 130 nm. The results of the spectral measurements indicate the presence of a relatively large concentration of electrons with energies > 15 eV over the entire pressure range. The fact that the current - voltage characteristic of the microdischarges has a positive slope over much of the current range where excimer radiation is emitted indicates the possibility of forming arrays of these discharges and using them in flat panel excimer lamps.

5618100 Solar powered flat lamp night light : Glynn Kenneth P Raritan Township, Hunterdon County, NJ, United States assigned to Ideal Ideas Inc

5618100 Solar powered flat lamp night light : Glynn Kenneth P Raritan Township, Hunterdon County, NJ, United States assigned to Ideal Ideas Inc

Some Properties of a Novel Far UV Xenon Excimer Barrier Discharge Light Source

AbstractElectrical and optical properties of dielectric barrier Xenon discharge lamps, selectively emitting Xe/172 nm vuv radiation from a multitude of transient discharge filaments have been investigated. The lamps used were uncooled and of the flat panel type with two dielectric quartz barriers and external metal electrodes. Such lamps can be considered as small scale models of much larger flat panel uv lamps. UV emission scales almost linearly with operating frequency below 10 kHz. Both uv emission and uv efficiency rise with increasing gap spacing. The specific 172 nm emission is in the range of 100 mW/cm2 for frequencies close to 100 kHz (no lamp cooling). External efficiency at high specific uv emission is close to 10%. Higher external efficiencies up to 20% are possible at lower frequencies of a few kHz, but at reduced specific uv flux.

カソードルミネセンス高輝度平面光源

A high-intensity flat vacuum fluorescent lamp utilizing cathode-luminescence has been developed for LCD backlighting. The apparatus used was a glass vessel consisting of two concave-shaped pieces of glass with two mesh-shaped grid electrodes and the line cathodes fixed at the solder glass fritting seal section between the front and rear pieces of glass. The lamp consists of tetrode. The glass vessel is made of Barium-Strontium glass, so that a high voltage can be applied to the anode and so that a high luminous efficiency can be obtained. As we adopt an interference filter and a liquid-cooling system to add high power to the phosphor layer, this lamp can produce an intensity of 70, 000 cd/m2 (Green). Moreover, excellent results concerning brightness uniformity, brightness control and temrperature stability are also obtained.This lamp is expected to be used for LCD backlighting of LC projectors and for head-up displays of cars and planes.

高輝度LED面発光光源

高輝度LED面発光光源

Hollow Cathode Spectral Lamps for Atomic Absorption Analysis

Abstract An estimate of the qualities of flat and cone bottom hollow cathode lamps for atomic absorption analysis was made comparing their calibration curves. The obtained results indicate that replacing the flat bottom cathode with a conical one, for the investigated (Fe, Ni, Al, Mo, Mg, Cu, Zn) elements, leads to a decrease of the optimum current strength while preserving even enhancing the concentration sensitivity at the same time.

Plant growth with new fluorescent lamps

Tomato seedlings were grown under seven kinds of fluorescent lamps, including two that are commercially available, and five experimental lamps. Detailed descriptions and spectral emission curves for these lamps are presented.The 78/22 lamp, which emitted most of its energy above 500 mμ, more than ten percent above 700 mμ, and had a sharp peak output at 660 mμ, generally produced superior fresh and dry weight yields. This effect may be due primarily to the high peak of energy emitted at approximately 660 mμ, combined with a considerable emission in the far-red, which in turn may be related to the red ↔ far-red reversibility phenomeon.The Com I lamp, which lacked the sharp peak output at 660 mμ and emitted more energy in the blue than the 78/22 lamp, was generally second only to the latter in promoting plant growth. A high moisture content was found in plants under this lamp in some experiments.The IRIII lamp had the sharp peak output at 660 mμ but greater output in the blue than the 78/22 lamp. The 282 lamp output was similar to the 78/22 but lacked the high peak. Both of these lamps generally gave improved results over those produced by commercial Gro-Lux, Warm-white, and FLAT lamps. This was attributed to the greater percentage of red and far-red energy emission by the former two lamps. The yields with the FLAT lamp were consistently lowest of all. This has been attributed to the high percentage of emitted energy in the blue and green portions of the spectrum.Both length of the test period (13 days versus 26 days) and light intensity (550 μw/cm(2) versus 1100 μw/cm(2)) may be important factors in determining which composition of spectral energy emission produces the greatest yields. Under low intensity and short test period the Com I light produced highest fresh- and dry-weight yields, but under high intensity and longer growth period the 78/22 lamp gave greatest yields. This effect may be due to inhibition of leaf expansion by red light in the early stages of growth.The experiments demonstrate that it is possible to develop a fluorescent lamp for plant growth that combines the desirable characteristics of both incandescent and fluorescent light. This work also shows that the tomato plant in the seedling stage grows best under an artificial light source with a high percentage of energy emission in the red, a considerable amount in the far-red, and a very small amount in the blue part of the spectrum.