Abstract: A laser power control circuit utilized in a laser scanner that comprises lasers for forming latent images on a photosensitive drum is provided. The laser power control circuit controls the laser emitting power of a multi-laser diode which has two laser diodes and one photo diode for monitoring the laser power. The photo diode simultaneously receives laser beams emitted from each of the laser diodes and outputs an output signal in response to the received laser power. The laser power control processor alternately controls the laser emitting power of each of the laser diodes for each time period which is assigned to each of the lasers. The laser emitting power of the laser diodes is controlled in accordance with the output signal from the photo diode.

Abstract: A laser scanning apparatus is provided with a laser diode that is driven to emit a laser beam, a scanning optical system that scans the laser beam emitted by the laser diode on a surface to be scanned, and a controller that drives the laser diode by supplying electrical current to the laser diode. The controller supplies an extra electrical current to the laser diode only at an initial stage of driving of the laser diode so as to cancel an effect of a rising delay of its output intensity.

Abstract: A multi-beam scanning apparatus has a scanning unit that has a plurality of semiconductor lasers and scans laser beams emitted from the plurality of semiconductor lasers; and a controller that transmits a standard signal associated with a control of the plurality of semiconductor lasers to the scanning unit. The controller has a standard signal generator that generates and outputs a sequence of pulse signals as the standard signal. The scanning unit has a plurality of laser drivers, a standard voltage generator, and a standard voltage setter. The standard voltage setter detects each of a plurality of common pulse signal sections of the standard signal in accordance with its signal-wave characteristic, and transmits each value of the plurality of standard voltage sections to a corresponding laser driver in accordance with a detected common pulse signal section.

Abstract: In a scanning optical device having an APC (automatic power control) circuit for controlling an output power of a laser diode, a reference value is determined by sampling saw-tooth wave which varies time elapses. A triggering system is provided to output a trigger signal, and the saw-tooth wave is sampled and held in response to the trigger signal. Based on the sampled and held value, i.e., the reference value and a value corresponding to the output power of the laser diode, an APC operation is performed.

Abstract: A semiconductor laser driving apparatus has a laser diode that emits a laser beam, a laser driving circuit that drives the laser diode by feeding a driving current in pulses to the laser diode, a conductor that conducts the driving current from the laser driving circuit to the laser diode, and an inductance adjuster that has a conductor-pattern for conducting the driving current and adjusting the magnitude of inductance in the conductor. A part of the conductor-pattern that makes the magnitude of the inductance a proper magnitude for emitting the laser beam in generally rectangular pulses, is selectively defined and conducts the driving current as a part of the conductor.

Abstract: To make compatible low consumption power formation of a control circuit of a light emitting element and high frequency formation of operational frequency band constituting a variety of usable combination elements of light emitting elements and light receiving elements, bias current is provided to a current mirror for dividing monitor current of a photodiode PD1 by a current source to thereby compensate drive function of a post stage in driving thereof by low current. Reference voltage of a current-voltage conversion portion is set in accordance with an input range of an operational amplifier of a gain adjusting portion at a post stage and input to the operational amplifier is fitted to an input range optimizing amplifying function. There are provided switching circuits SW1 and SW2 for selectively supplying monitor current from two photodiodes to respective APC loops of laser diodes LD1 and LD2 to thereby deal with a 2LD-1PD element and two of 1LD-1PD elements.

Abstract: A laser power control circuit utilized in a laser scanner that comprises lasers for forming latent images on a photosensitive drum is provided. The laser power control circuit controls the laser emitting power of a multi-laser diode which has two laser diodes and one photo diode for monitoring the laser power. The photo diode simultaneously receives laser beams emitted from each of the laser diodes and outputs an output signal in response to the received laser power. The laser power control processor alternately controls the laser emitting power of each of the laser diodes for each time period which is assigned to each of the lasers. The laser emitting power of the laser diodes is controlled in accordance with the output signal from the photo diode.

Abstract: To make compatible low consumption power formation of a control circuit of a light emitting element and high frequency formation of operational frequency band and constituting a variety of usable combination elements of light emitting elements and light receiving elements, bias current is provided to a current mirror for dividing monitor current of a photodiode PD1 by a current source to thereby compensate drive function of a post stage in driving thereof by low current. Reference voltage of a current-voltage conversion portion 4 is set in accordance with an input range of an operational amplifier 51 of a gain adjusting portion 5 at a post stage and input to the operational amplifier 51 is fitted to an input range optimizing amplifying function. A variation of frequency band or phase is restrained by adjusting gain by using a differential amplifier 53 of the gain adjusting portion 5.

Abstract: A power controller controls a power of a laser emitted from a semiconductor laser device which includes a laser diode and an internal photodiode integrally assembled in a small substrate. The laser diode is electrically energized by an electric current power source, and the laser power is detected as a first electric current signal by the internal photodiode. An external photodiode detects the laser power as a second electric current signal. A feedback controller controls the power source on the basis of one of the first and second electric current signals. The controlling of the power source by the feedback controller is based on the second electric current signal when the operation of the external photodiode is proper and normal. The controlling of the power source by the feedback controller is based on the first electric current signal when the operation of the external photodiode is improper and abnormal.

Abstract: A scanning apparatus. The scanning apparatus has a cascade scanning optical system in which a scanning line, made by a scanning laser beam emitted by a first laser scanning optical system of a plurality of laser scanning optical systems, and a second scanning line emitted by a second laser scanning optical system of the plurality of laser scanning optical systems, are prevented from deviating from each other in either a main scanning direction or a sub-scanning direction.