This optical scanning method yields a high quality image regardless of the size of the scanning area. An emission end of an optical fiber is displaced two-dimensionally to scan light emitted from the optical fiber, the emission end being displaced by an optical scanning actuator that includes a first driver and a second driver for driving the emission end in different directions. A non-circular scanning area is scanned by controlling, with a driver controller, a first drive signal supplied to the first driver and a second drive signal supplied to the second driver so as to rotate a scanning pattern of the light, while causing the scanning pattern to reciprocate repeatedly in a nearly parallel manner, and to change a length of the scanning pattern in accordance with a rotation angle of the scanning pattern.

For measuring the oscillation amplitude of a scanner mirror in a projection system of a motor vehicle headlight, a laser beam generated by a laser source is directed onto the scanner mirror and reflected by the latter so that the laser beam thus reflected is incident on a detector device (20) that has a plurality of photodetector elements (Q1, Q2, Q3, Q4) and there describes a curve (P) based on the oscillation movement of the scanner mirror. The center point of the curve (P) is offset by an offset value (x.sub.offset, y.sub.offset) from the center of the detector device (20). The time period (t.sub.ON,X, t.sub.ON,Y) in which the curve passes through the specific detector region (R.sub.X, R.sub.Y) that corresponds to a coordinate to be measured is determined; and the oscillation amplitude (x.sub.pp, y.sub.pp) in the direction of the specific coordinate is determined using the ratio of the time period (t.sub.ON,X, t.sub.ON,Y) determined in this manner to the total duration (T) of an oscillation period and the offsets (x.sub.offset, y.sub.offset).

An optical scanning apparatus includes a deflector for deflecting a beam emitted from a light source, the deflector including a rotatable polygonal mirror for reflecting the beam, a motor for rotating the rotatable polygonal mirror, a substrate carrying the motor and provided with a circuit for driving the motor, and a magnetometric sensor carried on the substrate; an optical box accommodating the deflector. The substrate is provided with two holes for fastening the substrate to the optical box. The optical box is provided with two contact portion contacting the substrate in a state that the substrate is fastened to the optical box through the two holes. The magnetometric sensor is disposed at a position closer to a line m connecting the two holes than to a line n connecting two positions on the substrate where the two contact portions contact.

An optical writing device, and a method of controlling the optical writing device. The optical writing device and the method includes controlling speed of operation of a light deflector based on image magnifying-power information in a sub-scanning direction parallel to a direction in which a surface of a photoconductor moves, and controlling a prescribed write clock frequency such that a number of clock pulses of write light will become a target number of pulses over a period where the write light scans an area within a prescribed distance in a main scanning direction, the target number of pulses being maintained even when the speed of operation of the light deflector is changed in the controlling the speed of operation of the light deflector. The write clock frequency controller maintains the target number of pulses even when the speed of operation of the light deflector is changed by the light-deflector controller.

A first receiving recess (44d) and a second receiving recess (44e) are formed on a surface of the housing, on which a pair of image forming lenses (47) are placed, to receive a first temperature sensor (101a) and a second temperature sensor (101b), and are formed in positions, in which thermal deformation characteristics of the housing are approximately identical at one side and the other side of a first straight line K1, while interposing the first straight line K1 therebetween.

According to aspects of the embodiments, there is provided process and architecture for enabling multiple digital micromirror devices (DMDs) that include optical modulation elements configured to modulate light outputting from a light source, and a projection unit configured to project light modulated by the optical modulation elements on a printing plate. Image defects due to misalignment in the cross-process direction of the output from the DMDs are discovered by using a single test pattern image and combined with knowledge of how individual pixels are rendered to register printing elements which can render a variable number of pixels. Misalignment errors can be corrected by selecting a different set of mirrors for a given DMD.

An optical scanning apparatus includes a deflector for deflecting a beam emitted from a light source, the deflector including a rotatable polygonal mirror for reflecting the beam, a motor for rotating the rotatable polygonal mirror, a substrate carrying the motor and provided with a circuit for driving the motor, and a magnetometric sensor carried on the substrate; an optical box accommodating the deflector. The substrate is provided with two holes for fastening the substrate to the optical box. The optical box is provided with two contact portion contacting the substrate in a state that the substrate is fastened to the optical box through the two holes. The magnetometric sensor is disposed at a position closer to a line m connecting the two holes than to a line n connecting two positions on the substrate where the two contact portions contact.

An optical scanning device includes a deflector configured to deflect first and second beams to scan an effective area of a first scanned surface in a main scanning direction, and first and second imaging optical systems configured to guide the first and second beams deflected by the deflector to first and second areas, respectively, which are included in the effective area and different from each other in the main scanning direction. In the main scanning direction, the first area and the second area are asymmetric in width with respect to an optical axis.

An optical writing device, and a method of controlling the optical writing device. The optical writing device and the method includes controlling speed of operation of a light deflector based on image magnifying-power information in a sub-scanning direction parallel to a direction in which a surface of a photoconductor moves, and controlling a prescribed write clock frequency such that a number of clock pulses of write light will become a target number of pulses over a period where the write light scans an area within a prescribed distance in a main scanning direction, the target number of pulses being maintained even when the speed of operation of the light deflector is changed in the controlling the speed of operation of the light deflector. The write clock frequency controller maintains the target number of pulses even when the speed of operation of the light deflector is changed by the light-deflector controller.

A light source control device, includes circuitry to: apply a threshold current, a first emission current, and a first correction current to a light source to drive the light source to emit light to form a first pixel, and apply the threshold current, a second emission current, and a second correction current to the light source to drive the light source to emit light to form a second pixel, wherein the circuitry calculates a value of the second correction current by multiplying a value of the first correction current by a ratio of a value of the second emission current to a value of the first emission current, the value of the second emission current being greater than the value of the first emission current.