Ricoh Company, Ltd.

Toshitaka Senma

Tomoatsu Imamura

Kazuyuki Shimada

Takamasa Hayashi

Masumi Sato

Tomonori Tanaka

Mitsuo Tanaka

Shigeyuki Araki

Goro Mori

Masami Miyajima

Takundo Isobe

Masaru Takahashi

Masahiro Yamamoto

An image forming apparatus which forms an image on a recording medium at a number of different dot densities. The image forming apparatus includes a light source part for emitting a light beam, a light detection part for detecting a light beam from the light detection part detecting a light beam from the light source part and for supplying a signal indicative of a power of the detected light beam when a monitored voltage obtained by the light beam is approximately equal to a reference voltage, a memory part for storing a number of power data corresponding to the number of different dot densities, an input part for inputting a first dot density selected, a power data control part for supplying a signal indicative of a changed power data which is changed from a value of said power of the detected light beam with a power data stored in the memory means which is located by the selected first dot density, and a driving part for operating the light source with the signal from the power data control part allowing the light source to emit a light beam with the changed power, the changed power being appropriate for forming an image on the recording medium at the selected first dot density.

Image forming apparatus with plural dot densities

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.

Image forming apparatus capable of forming an image by dots having

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 side but before the last sheet is discharged.

Method of forming an image on both sides of a sheet

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.

Semiconductor laser unit

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.

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Yokohama, Japan

Toshitaka Senma