Fluorescent Lamp Stand With Built-in Single-transistor Separately-excited Inverter

Appearance of fluorescent lamp stands with built-in single-transistor separately-excited inverter

Fig.1 Appearance of fluorescent lamp stands with built-in single-transistor separately-excited inverter

Appearance of single-transistor separately-excited inverter

Fig.2 Appearance of single-transistor separately-excited inverter

One negative characteristic of a fluorescent lamp and other types of discharge lamps is that voltage drops as current rises. This means that a ballast device is essential for achieving stable light emission in lamps of this type. A fluorescent lamp also requires a starter circuit such as a “glow starter” to quickly initiate emission. As a result, the fluorescent lamp came to be integrated with the ballast and starter circuit in one unit.

However, the traditional copper-iron ballast, which consists of copper wire wrapped around an iron core, is bulky and heavy, and this made fluorescent lamps unsuitable for desktop stands for some time. But in October 1984, a fluorescent lamp appeared with a sleek stand containing no ballast or glow starter. This is an “inverter” or “”high-frequency-starter” type of fluorescent lamp.

This new type of fluorescent lamp incorporates an inverter circuit instead of a ballast. The main component of this circuit is the single-transistor separately-excited inverter. The use of only one transistor here enables a smaller fluorescent lamp to be achieved.

This inverter device converts commercial AC power (50/60 Hz) to high-frequency AC power (20-50 kHz) resulting in little flicker, and because startup is instantaneous, there is little noise emitted from the fixture. The device also saves on energy since loss generated by eddy currents in an iron core (core loss) and loss associated with the resistance of copper wire (copper loss) as in copper-iron ballasts are nearly zero.

In 1985, the Illuminating Engineering Institute of Japan presented Atsuo Koyama, Mitsuo Akatsuka, Naoto Nakagawa, Takehiko Koshimitsu (Hitachi Lighting Company,Ltd), Takahiro Nakamura (Hitachi Sales Corporation), and Toshiyuki Moriya (Hitachi, Ltd.) with the Japan Lighting Award for their groundbreaking work in devising a single-transistor separately-excited inverter and adopting a high-frequency-starter system in fluorescent lamp stands. The appearance of a fluorescent lamp stand with such a novel design that could not be considered for a ballast-equipped stand has had a significant impact on the lighting industry.

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