Patent ID: 7239336

Claim:
An image exposing apparatus comprising: beam scanning means for scanning a beam emitted from a semiconductor laser device to photosensitive material; laser driving means for driving the semiconductor laser device, the laser driving means being operable to vary its driving current to the semiconductor laser device in accordance with a received image signal; and laser output controlling means operable to measure current-beam output characteristics of the semiconductor laser device over a predetermined current range and then set a correlation between said image signal for the laser driving means and the driving current for the semiconductor laser device, based on the measurement information; wherein said laser driving means includes a multiplier circuit for multiplying an input value of the inputted image signal by a primary coefficient and an adder circuit for adding a constant to its product; said laser output controlling means includes a constant feedback controlling circuit for varying said constant in such a manner as to cause the beam output from the semiconductor laser device to correspond to a zero level signal input to said adder circuit and a primary coefficient feedback controlling circuit for varying said primary coefficient in such a manner as to cause the beam output from the semiconductor laser device to become a beam output that corresponds to a beam output adjusting signal level input to said multiplier circuit; and wherein said laser output controlling means determines said constant by energizing said constant feedback controlling circuit when the input to said adder circuit is set to said zero level signal input and then determines said primary coefficient by energizing said primary coefficient feedback controlling circuit when the input to the multiplier circuit is set to the beam output adjusting signal level signal input, thereby to effect said measurement of the current-beam output characteristics of the semiconductor laser device in parallel with said setting operation of the correlation between the received image signal of the laser driving means and the driving current for the semiconductor laser device.