Hitachi Koki Co., Ltd.

Hitachi, Ltd.

Minoru Ohshima

Akira Arimoto

Takeshi Mochizuki

Minoru Seino

Susumu Saito

Kazutoshi Obara

Masami Ishikawa

Tsukasa Ogawa

Susumu Saitoh

Takao Umeda

Makoto Nakura

Yasuyuki Tsuji

Shigenobu Katagiri

Masuo Kasai

Osamu Namikawa

Shuichi Morio

Takashi Nakazawa

Tohru Miyasaka

A device for measuring a surface potential at a photosensitive body including: a potential sensor for measuring surface potentials at a plurality of positions on the photosensitive body; a plurality of sample hold circuits; and an adder for adding each measured surface potential held in each sample hold circuit, or an adder which adds up each measured surface potential and average the sum. The addition or averaging of the measured values serves to eliminate eccentricity-induced errors and noise in the surface potential measurements, thereby allowing a correct surface potential to be obtained.

Device for measuring surface potentials at photosensitive body and

A beam position control apparatus in which a light beam is led into a light detector from a light generating source through a movable reflector and positioning of the light beam is performed by a servo control circuit for feeding a signal from the light detector back to the movable reflector, comprises: an oscillator for oscillating in response to an initializing signal and moving the movable reflector to move the beam onto the light detector; and a control switch for separating the oscillator and the movable reflector from each other in response to the signal from the light detector, the oscillator and the control switch being arranged in the servo control circuit.

Beam position control apparatus

A double beam scan type optical apparatus for use in a laser printer or the like. Such apparatus comprises two light sources and a lens system which provide scanning means for scanning a surface with parallel output light beams of the two light sources and beam distance controlling means for controlling the distance between the light beams. The reliability of the invention is improved by monitoring the intensity of the beams. Beam intensity checking means provide signals to verify that the intensity of each beam is maintained equal thus assuring that no abnormal conditions exist with the light sources or the lens system of the apparatus.

Double beam scan type optical apparatus

A scanning apparatus for use in a laser beam printer or the like comprising a control means for varying the spacing between adjoining scanning beams of a plurality of laser beams, which further comprises a plurality of light sources, a means for changing intensity, including on/off states, of the beam from the light sources, and a rotating polygonal mirror for allowing the beams to scan the scanned plane in parallel, and is adapted, in accordance with the value of the pixel density of information to be recorded, such that, in the beam scanning direction, the area exposed to the beam is changed by changing the width of a beam intensity modulating pulse, and in the direction perpendicular to the beam scanning, the number of revolutions of the rotating polygonal mirror is changed.

Light beam scanning apparatus with controller for varying spacing

An optical scanner and method in which light beams from a plurality of sources are directed onto a medium to form a composite spot. The relative positions of the beams are detected and changed to change the diameter of the composite spot so that lines formed by such spots appear unbroken. The modulating times, intensities and number of sources of the beams can also be varied to provide a linear relation between the dither matrix and the picture element density.

Optical scanner and method for generating and detecting a composite dot

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Ibaraki, Japan

Minoru Ohshima