Abstract: An image forming apparatus which forms an image on a recording medium at a number of different dot densities.

Abstract: An image forming apparatus capable of changing the diameter of a dot in the main and subscanning directions to form various kinds of dots and thereby high resolution images with tones. A data converting circuit separates input image data into pulse width modulation data and power modulation data and distributes them to a pulse width modulating circuit and a power modulating circuit. The pulse width modulating circuit changes the duration of a laser beam issuing from a laser diode to change the diameter of a dot in the main scanning direction. The power modulating circuit changes the exposing energy of the laser beam per unit area and unit time in order to change the dot diameter in the subscanning direction. The modulating circuits control an image writing device in cooperation so as to produce a high resolution image with tones.

Abstract: A method of forming images on both sides of a plurality of sheets by an image forming apparatus having an image forming unit and a sheet path selection unit comprises a repetition of a group of substeps as a job unit, the group of substeps including substeps of feeding a predetermined number of new sheets to the image forming unit, forming the images on a first side of the sheets, turning over the side of the sheets by the sheet path selection unit, refeeding the predetermined number of sheets to the image forming unit responsive to the turning-over of each sheet, forming the images on a second side of the sheets by the image forming unit, and discharging the predetermined number of sheets by the sheet path selection unit each time the sheet is formed with the image on the second side thereof, wherein said substep of feeding the new sheets is commenced for a new job unit when the last sheet of the currently performed job unit is fed to the sheet path selection unit after formed with the image on its second si

Abstract: A semiconductor laser unit includes a casing, a printed circuit board fastened to the casing, and a laser diode unit which includes a laser diode and a photodiode for monitoring a laser beam emitted from the laser diode. The laser diode unit is accommodated in the casing. The semiconductor laser unit also includes a monitor output amplifier for amplifying an output signal of the photodiode, and a reference voltage generator for generating a reference voltage signal which is to be compared with an output voltage signal of the monitor output amplifying means in order to set a light intensity of the laser beam to a predetermined value.

Abstract: A semiconductor laser control apparatus for controlling an intensity of light emitted from a semiconductor laser by controlling a drive current to by supplied to the semiconductor laser, includes a first circuit which roughly determines a first value of the drive current so as to obtain a intensity of light near a desired intensity of light emitted from the laser diode, a second circuit which precisely determines a second value of the drive current so as to obtain the desired intensity of light, after determining the first value of the drive current by the first circuit, and an adder which adds the first value of the drive current determined by the first circuit and the second value of the drive current determined by the second circuit. The drive current having an added value is supplied to the semiconductor laser.