| 摘要 |
<p>PROBLEM TO BE SOLVED: To make it possible to properly control the pulse width of a pulse width modulation signal by a method wherein a detecting means for detecting the amount of light emitted from a light emitting element is provided in a device, in which an image is drawn by the light emitted from the light emitting element, so as to control a pulse width setting means on the basis of the amount of light to be detected. SOLUTION: At the controlling of a pulse width, an image data generating part 201 generates controlling image data on the basis of a direction sent from a controlling part 205. A pulse width modulation part 202 pulse width-modulates that image data, resulting in producing a pluse width modulation signal. A laser driver 206 drives the laser diode 207a of a light emitting part 207 on the basis of the above-mentioned width modulation signal. At this time, a photo diode 207b for detecting the amount of light emitted from the laser diode 207a is equipped so as to amplify that output with an OP amplifier 209 and then supply it to the controlling part 205, in which an A/D converter 205c controls the set values of a minimum pulse width setting part 203 and of a maximum pulse width setting part 204 on the basis of the detecting signal of the amount of light.</p> |
