| 摘要 |
PURPOSE:To maintain the gas pressure in a laser tube always at a proper value by a method wherein the fluctuation of a discharge voltage detecting signal caused by the fluctuation of an input voltage is compensated and the discharge voltage signal input of a comparator circuit is always a voltage proportional to the gas pressure. CONSTITUTION:An AC input, which is the same one as inputted to a DC source 10, is inputted to a transformer 40 and its secondary voltage is rectified by a rectifier 42 and smoothed by a capacitor 44 to obtain a DC voltage proportional to the input voltage. The DC voltage is divided by the series circuit of resistances 46 and 48 and supplied to a reverse input of a comparator circuit 30, to which the discharge voltage detecting signal Veb is inputted, as an input voltage detecting signal Va. Therefore, the input voltage detecting signal Va is added to the discharge voltage detecting signal Veb at the reverse input of the comparator circuit 30. In other words, connections at the reverse input of the comparator circuit 30 form an adder circuit. |
