Tadao Uetsuki

A study on the ignition characteristics of magnetic coupled electrodeless lamp

Summary form only given: Almost twenty years have passed since the first electrode-less lamp operated at 13.56 MHz was put on the market. Since then, it has come to be expected that the lumen output and the efficiency of these lamp systems would be improved, and as a result research to reduce the operating frequency has been done. This is because if the operating frequency were decreased, many semiconductor devices for higher lumen output could be used and the switching loss could be reduced for higher efficiency. The present electrode-less lamp system operated at 135 kHz has higher efficiency and output than the high pressure mercury lamp system which is very popular in the market. Thus the characteristics of this lamp when it is turned on have been researched and developed. However, the ignition mechanism of the electrode-less lamp has not yet been completely worked out. To grasp the ignition voltage and time is very important for designing this lamp system, because these influence the cost of the system. The authors investigated how to reduce the ignition time. Generally it is explained that the discharge ignites when equation (1) is fulfilled. gamma(exp(alphad)-1) = 1 (1) Where a is the coefficient of ionization by collision, gamma is the number of the second electrons emitted from the cathode which one ion collides with, and d is the distance between electrodes. As the electrode-less lamp has no electrode, this definition is not applicable. With regard to the ignition for magnetic coupled electrode-less lamp, it was reported that there are theoretically two types of ignition, which are E-discharge mode and H- discharge mode. However, the definition of the ignition actually is regarded as the time when the H discharge occurs. Thus in order to reduce the ignition time it is very useful to understand the mechanism about how E-discharge changes to H-mode. The authors observed the starting state of the electrode-less lamp and found out that something to produce the initial electron inside the lamp bulb before starting should be set in.

A study on the relationship between electrode materials and characteristic S of CCFL's negative glow plasma

Summary form only given. CCFLs (cold cathode fluorescent lamps) generally used for the backlight of the LC-TV and the note-PC are always expected to the improvement of the electrode to make more lamp current flow for getting higher luminance. To improve the electrode to get the higher luminance, it is very important to grasp the electron emission ability of the cathode. Authors have considered that the electron emission ability determined by the nature of the material could be evaluated by the cathode fall voltage (CFV), and that CFV has the intimate relationship to the performance of negative glows (NGs) plasma. 2 kinds of electrode materials, namely Ni and Mo, were used for this research. Though the common electrode of CCFL is hollow cathode, the electrode used here were in the shape of the plate, which had a length of 5.2 mm, a width of 1.7 mm and a thickness of 0.1 mm. This is because it is necessary to observe the NGs plasma for grasping the basic relationship between CFV and the performance of NGs plasma. The lamp diameter was 4 mm and had Ne (8 kPa) and Hg vapor. First, the relationship between a state of NGs plasma and discharge current was observed for each kind of electrode materials. The area of NGs plasma increased to whole area of the electrode as the discharge current increased. However the way to increase depended on the electrode materials. Secondly, the relationship of the CFV to the discharge current was measured. The method to measure the CFV was developed by improving the method for measuring the CFV of the fluorescent lamp. The CFV of Ni was higher than that of Mo. The ways of the change of the CFVs were similar in the following respect. That is to say, CFVs were constant until some discharge current, then increased as the discharge current increased. While, the increasing rates of CFVs were different from each other. Authors consider that the difference of gamma-coefficient causes the difference of CFVs increasing rate

Influence of Metal Plate on Starting Voltage of Fluorescent Lamps

ランプ両端の印加電圧 を変化 させ、1秒 以内に始動 しない印加電 圧の上限値 を測定 した。パラメータをラ ンプと近接 導体間の距離 と し、近接導体 を接地 した場合 と接地 しない場合につ いて行 った。 実験 に用いたランプは、40Wの 丸管蛍光 ランプと100Wの 二 重環状 蛍光ランプであ る。近接導体材料 には鉄 を用 いた。 3.実 験結果 図2に 丸管蛍光 ラ ンプの実験 結果 を示 す。 近接導 体 を接 地 し た場合 、つ ま りラ ンプの一端 と近接 導体 が同電位 の場合 は放電 開始電圧が低 くなる ことを示 している。 図3に 二重環状 蛍光 ランプの実験結 果 を示す。放 電開始電圧 が近接 導体 の接地及 び距離に影響 され ないこ とを示 している。 この こ とよ り、丸管蛍 光ラ ンプは近接 導体の影響 を受 けるが、 二重環状蛍光 ランプは影響 を受 けない ことが明 らかになった。 4.考 察 各蛍光 ランプにおいて、始動直前の電圧 をランプ両端に印加 した ときの微放電状態 を図4と 図5に 示す。丸管蛍光 ランプは ランプの一端(高 圧側)に 微放電が形成 されるの に対 し、二重 環状蛍光 ランプは ランプ両端 に微放電 が形成 されてい る。 この観察結果か ら、丸管蛍光 ランプは近接導体 とラ ンプー端 とに電流が流 れ、二重環状蛍光 ランプは放電 路 間を電流が流れた と考 えられる。 この違いは、二重 環状蛍光 ランプの放電路間の距離が短い ことか ら生 じ た と考 えている。 この近接導体 に電流が流 れない こと が近接 導体 の影響 を受 けなか った原因 と推測 している。 図1実 験回路