Abstract: A first current generator circuit generates a first current having a current value variable in accordance with a first control signal. A second current generator circuit generates a second current by limiting the first current so as to have a current value variable in accordance with a second control signal. A third current generator circuit generates a third current by limiting the second current so as to have a current value variable in accordance with a third control signal, and supplies the third current to the semiconductor laser element. Rates at which the first and second control signals change are set to be lower than a rate at which the third control signal changes.

Abstract: A first current generator circuit generates a first current having a current value variable in accordance with a first control signal. A second current generator circuit generates a second current by limiting the first current so as to have a current value variable in accordance with a second control signal. A third current generator circuit generates a third current by limiting the second current so as to have a current value variable in accordance with a third control signal, and supplies the third current to the semiconductor laser element. Rates at which the first and second control signals change are set to be lower than a rate at which the third control signal changes.

Abstract: A semiconductor laser drive apparatus includes: a current setting circuit that stores a first set value for a light-emission current obtained by subtracting a first bias current used when the semiconductor laser element emits light, from a drive current used when the semiconductor laser element emits light, a second set value for the first bias current, and a third set value for a second bias current used when the semiconductor laser element does not emit light; a first current generator circuit that generates a first input current from the first set value; a second current generator circuit that generates a second input current from the second set value and a third input current from the third set value; and a switching circuit that supplies a sum of the first and second input currents to a drive circuit when a light-emission control signal is on, and the third input current to the drive circuit when the light-emission control signal is off.

Abstract: A semiconductor laser drive apparatus includes: a current setting circuit that stores a first set value for a light-emission current obtained by subtracting a first bias current used when the semiconductor laser element emits light, from a drive current used when the semiconductor laser element emits light, a second set value for the first bias current, and a third set value for a second bias current used when the semiconductor laser element does not emit light; a first current generator circuit that generates a first input current from the first set value; a second current generator circuit that generates a second input current from the second set value and a third input current from the third set value; and a switching circuit that supplies a sum of the first and second input currents to a drive circuit when a light-emission control signal is on, and the third input current to the drive circuit when the light-emission control signal is off.