Patent ID: 8786653

Claim:
A light quantity control device comprising: a light quantity detecting unit that detects a quantity of laser light emitted from semiconductor laser elements which are mounted on a plurality of circuit devices; and an output unit that is provided on at least a reference circuit device among the plurality of circuit devices and that outputs, to another circuit device other than the reference circuit device among the plurality of circuit devices, an output result which is obtained through comparison and correction of a value detected by the light quantity detecting unit and a reference value, wherein each of the plurality of circuit devices includes: a reference current generating unit that generates a reference current, a comparison and correction unit that compares the reference current with a photocurrent which is output from the light quantity detecting unit, after converting the reference current and the photocurrent to voltages, and that performs correction so that the voltages are made equal to each other, a current controller that controls, in accordance with an output result obtained from the comparison and correction unit, a driving current for driving the semiconductor laser elements; and an operation stopping unit that is electrically coupled to the reference current generating unit and the comparison and correction unit, wherein the operation stopping units are configured to stop the operation of the reference current generating unit and the comparison and correction unit of the another circuit device other than the reference circuit device among the plurality of circuit devices.