Abstract: A laser beam printer is provided with a sensor for controlling the timing of inscribing image data on a photosensitive member by means of a laser beam scanning the surface of the photosensitive member. The output signal of this sensor rises when the laser beam reaches a prescribed position and falls when the laser beam passes the prescribed position. The time between the rising time and the falling time is used as the standard. Inscription of image data in each scanning line is started after elapse of a prescribed time following the standard time. The standard time remains unchanged in spite of a possible change in the sensor output. On the photosensitive member, the position for starting inscription of each scanning line can be set at the fixed position with high accuracy.

Abstract: An information record/pickup head assembly for an optical information recording and/or reproducing apparatus using an optical information storage disk, comprising a stationary optical unit and a movable optical unit movable with respect to the information storage disk loaded, wherein the stationary optical unit emits a beam of light toward the movable optical unit which then re-directs the incident beam toward the information storage disk while returning to the stationary optical unit the beam of light reflected from the information storage disk. A focusing operation is carried out in the stationary optical unit.