| 摘要 |
PURPOSE:To eliminate an afterglow due to a glow discharge and to execute the reading precisely by interrupting the preheating current of a fluorescent lamp at the moment that a high voltage for blinking said lamp is turned off and keeping an interrupting state for a specified period. CONSTITUTION:When a signal FLON inputted from a controller through a resistance 6 comes to zero, a transistor TR4 is turned on to supply an electric power source to a blocking oscillator OS2. For this period, a voltage V0 is outputted between filaments FL1 and FL2 of a fluorescent lamp F. When the lighting up time is terminated, the signal rises to ''1'', and at the moment a preheating circuit 1 sets a signal PREHT outputted to a switching circuit S1 to ''1'' for a specified period. Thus preheating voltages V1 and V2 are turned off for the specified period. |
