Discharge waveform for a narrow-tube lamp and its improvement using a switching circuit

摘要

References(3) The discharge voltage waveform deteriorates as the discharge tube diameter is reduced. The relationship between discharge voltage waveform and discharge characteristics are calculated using Fourier series expansion, and examined by experiment. The deterioration causes a high sustaining line voltage and a low lamp power factor. High sustaining line voltage in a narrow-tube lamp requires a lower discharge voltage than that for a conventional fluorescent lamp. This produces one of the limitations for reducing discharge tube diameter. The circuit methods that alleviate the above limitation are investigated. In the result, superimposition of pulsed voltage on the discharge voltage during the relight phase proves to be a very efficient way of reducing wareform deterioration. A small capacitance of 0.068 μF connected across the lamp improves the lamp power factor by 1.2%. The other method, the ballast-plus-switching-circuit, can increase lampefficacy by 5.2%.