Patent ID: 7269193
Filing Date: 2007-09-11
Classification: H04N

Abstract:
1. A semiconductor laser driving circuit used in an image recording apparatus for recording an image using a light beam from a semiconductor laser as an exposure light source, said light beam from said semiconductor laser being subjected to pulse modulation in correspondence with a command signal for controlling turn-ON/turn-OFF of said semiconductor laser, or an output light amount of said light beam emitted from said semiconductor laser, comprising: an error amplifier for amplifying a difference between said command signal and a signal fed back from said semiconductor laser to output an output signal, said output signal in a turn-ON state of said semiconductor laser being opposite in voltage polarity to said output signal in a turn-OFF state of said semiconductor laser; a diode and a resistor connected in series between an input terminal and an output terminal of said error amplifier; and a driver for driving said semiconductor laser based on said output signal from said error amplifier, wherein said diode is connected to apply a forward bias across said diode in said turn-OFF state of said semiconductor laser, and wherein a resistance value of said resistor is set so that a current which is nearly equal in amount to that caused to flow through said error amplifier when said semiconductor laser is in said turn-ON state in case that said semiconductor laser is subjected to pulse width modulation or pulse number modulation as said pulse modulation, or when said semiconductor laser is in said turn-ON state and emits said light beam with an intermediate level amplitude in case that said semiconductor laser is subjected to pulse amplitude modulation as said pulse modulation, is caused to flow through said error amplifier in said turn-OFF state of said semiconductor laser via said diode and said resistor.