Patent ID: 6295079
Filing Date: 2001-09-25
Classification: B41J,G02B,H04N

Abstract:
A scanning optical unit comprising:an acousto-optic modulating element including an acousto-optic modulating medium and a transducer which generates ultrasonic waves, and when a laser beam emitted from a laser light source passes through the acousto-optic modulating medium, the acousto-optic modulating element diffracts the laser beam by ultrasonic waves inputted by the transducer;main scanning/deflecting means for deflecting, in a main scanning direction of a recording medium, the laser beam which was diffracted by the acousto-optic modulating element;a reflecting mirror which is provided outside of an exposure region of the recording medium, and reflects the laser beam from the main scanning/deflecting means; anda sensor for determining a main scanning start position by receiving the laser beam reflected by the reflecting mirror,wherein a predetermined region of the recording medium is exposed by the laser beam deflected in a main scanning direction, and a distance, to the transducer from an illuminated position of the laser beam which is a diffracted position of the laser beam within the acousto-optic modulating medium, is set on the basis of a reflected position on the reflecting mirror of the laser beam received by the sensor with respect to a recording medium side end portion of the reflecting mirror, a main scanning speed of the laser beam, and a propagation speed of ultrasonic waves within the acousto-optic modulating medium.