ELECTRONIC BALLAST FOR FLUORESCENT LAMP

申请公布号：

JP2007258134(A)

申请号：

JP20060084611

申请日期：

2006.03.27

申请公布日期：

2007.10.04

申请人：

OSRAM-MELCO LTD

发明人：

KONDO KAZUYOSHI

分类号：

H05B41/24

主分类号：

H05B41/24

摘要：

PROBLEM TO BE SOLVED: To provide an electronic ballast for fluorescent lamps for improved life of a fluorescent lamp by shifting from a preheating state to a lighting state when "Rh/Rc=4.0" is detected after resistance ratio Rh/Rc for each filament is detected. SOLUTION: The electronic ballast comprises an output circuit 5 capable of changing between a preheating state for outputting a preheating voltage of filaments 6a and 6b and a lighting state for outputting a voltage for lighting which is higher than for preheating, and an electrode characteristics detecting circuit 7 for calculating a resistance value of the filaments 6a and 6b. It also comprises a preheating current control part 4a which controls a timing for shifting the output circuit 5 from the preheating state to the lighting state, based on the negative electrode resistance ratio Rh/Rc calculated from both a resistance value Rc of the filament 6a before preheating which is calculated by allowing such micro current as the resistance value of the filaments 6a and 6b do not change to flow just before starting of a fluorescent lamp, and a resistance value Rh of the filament 6a after preheating which is calculated by the electrode characteristics detecting circuit 7 when starting the fluorescent lamp 6. COPYRIGHT: (C)2008,JPO&INPIT