Rader, Fishman & Grauer PLLC
Light emitting device drive and image forming apparatus
If an abnormal current is applied to a laser diode at the rise time and fall time of a power voltage, a laser diode's life may be shortened. In a laser diode drive, circuits monitoring a current voltage are set up in two systems. At the same time, the monitor voltage of one system that controls the on/off operation of the internal bias voltage is set high relative to a monitor voltage of the other system controlling an output current; until the internal bias voltage becomes stable when power is on and before the internal bias voltage cuts off and makes the circuit operation unstable when power is off, by giving another reference voltage in lieu of a reference voltage as the reference voltage of the voltage-current conversion circuit, the output status of the voltage-current conversion circuit is controlled in the direction of decreasing a current that is applied to the laser diode, so that the laser diode is prevented from receiving an abnormal current at the rise time of the power voltage.
Sony Corporation
G
G06K
inventional
Shinichi
Watanabe