| 摘要 |
PROBLEM TO BE SOLVED: To provide a small and highly efficient lighting device where heat loss due to on-resistance of a full bridge inverter is greatly reduced, by setting first and second switch means in a cut-off state during a starting period, and releasing first and fourth switching elements from a lamp starting circuit system. SOLUTION: Heat loss of a full bridge inverter 3 is provided using a timer means 20 effectively. Output of the timer means 20 is first supplied to switch means 16, 17, and SW1 and SW2 are cut off during a starting period. Second, during the starting period added with a delay time, generation from a pulse generating circuit is stopped to hold a Low level, switching elements Q2, Q3 are in a conductive state, and switching elements Q1, Q4 are in a cut-off state. Thus, high voltage is not impressed onto all power MOSFETs of switching elements Q1-Q4 even during starting of the lamp. After a prescribed time, rectangular wave lighting is provided. Therefore, elements that have low pressure resistance and low heat loss can be used. |
