| 摘要 |
PURPOSE:To determine life corresponding to a laser used precisely by giving a control section an alarm on the life of the laser when the supply voltage of an amplifier in an AOM driver is lowered to voltage lower than a controllable limit value by a predetermined voltage section. CONSTITUTION:When the driving time of a laser-beam generating section 1 is increased and an output P from laser power gradually lowers, modulation efficiency eta augments by the operation of a level control circuit in order to keep the output level Pd of laser beams on the surface D of a photosensitive body constant. That is, the supply voltage Vrf of an optical modulation element (AMO)2 and an amplifier (AMP)22 in a driver 21 also increases simultaneously, and the voltage Vrf is applied to one terminal for a comparator 26, and compared with voltage E1. The reference voltage (E1+E2) of a comparator 20 is set at a value equal to limit voltage Vrf' where modulation efficiency etacan be controlled, but the reference voltage E1 of the comparator 26 is set at a value lower than that by voltage E2. When the output P from laser power lowers and voltage Vrf reaches Vrf>E1, the comparator 26 transmits a laser-life signal through which the expiration of the life of a laser in a short time is messaged. |
