In a scanning optical system including a polygon mirror for dynamically deflecting N laser beams corresponding to N color components and an imaging optical system for converging the laser beams into spot beams on N photosensitive drums respectively, the imaging optical system includes: a front lens group for converging the laser beams principally in a main scanning direction while deflecting the beams to deviate from its optical surface reference axis; and N rear lens groups for converging the laser beams principally in an auxiliary scanning direction respectively. The rear surface of the front lens group and front surfaces of the rear lens groups are formed as two-dimensional polynomial aspherical surfaces. Concretely, the rear surface is formed as a step-like optical surface having N discrete areas of different heights. By the system, the laser beams are separated sufficiently to match the intervals between the photosensitive drums without the need of long optical paths, without deteriorating the scanning performance, and without the need of using mirrors which cause color misregistration and increase costs.

Scanning optical system

Disclosed in an optical scanning apparatus which includes a deflecting unit comprised of a rotary polygon mirror for deflecting a light beam radiated from a light source unit, and a scanning optical system for guiding the light beam deflected by the deflecting unit to a surface to be scanned. In the optical scanning apparatus, individual elements are set such that a diameter of a circumscribed circle of the rotary polygon mirror, the number of deflecting facets of the rotary polygon mirror, an incident angle of the light beam on the deflecting facet at the time when the light beam scans a scanning center, a maximum swing angle of the deflecting facet at the time when an effective scanning range is scanned, and a magnification of the scanning optical system in a sub scanning section can satisfy a predetermined condition, thereby reducing an unevenness of pitches due to a deflecting-facet fall of the rotary polygon mirror, and readily achieving a highly precise and fine image.

Optical scanning apparatus and image forming apparatus using the same

An image forming apparatus having an image transfer belt for transferring a plurality of images, a first image forming station for forming a first registration indicia on the image transfer belt, and a second image forming station for forming a second registration indicia on the image transfer means. The image forming apparatus further includes a registration indicia sensor belt for sensing positioning of the first and second registration indicia, a misregistration determining portion for determining misregistration of the second image forming station based upon the positioning of the second registration indicia relative to the first registration indicia, and a correcting portion for correcting the misregistration of the second image forming station as determined by the misregistration determining portion.

Method and apparatus for tandem color registration control

A first beam separation device is arranged either to allow the light beams to enter and pass or to reflect the light beams in accordance with a direction of entrance of the light beams A second beam separation device is provided either to allow or to reflect the light beams having passed through the first beam separation device in accordance a wavelength thereof The light beam passing through the second beam separation device scans one of plural scan objectives and the light beam reflected by the second beam separation device is further reflected by the first beam separation device and then scans the other one of the plural scan objectives A first imaging device is provided to correct a f-theta (fθ) performance and a curvature of an imaging plane to enable the light beams to scan the plural scan objectives at a constant speed The first imaging device is integral with the first beam separation device

Optical writing device and image forming apparatus

An image forming apparatus includes a plurality of image carriers arranged side by side along the outer surface of a conveying portion of a transfer belt. The transfer belt is stretched between a first upstream roller and a second downstream roller. An image forming medium is conveyed on the belt so as to have multiple color images transferred thereto. The transfer belt has a swing lever so as to move the belt between a horizontal full color position and an inclined monochrome position. A stationary support roller which is arranged within the transfer belt and at a position nearer to the second downstream roller maintains a position of the image forming medium constant even when a monochrome image is being transferred. In addition, an electrostatic attraction roller located outside the transfer belt is arranged at a specific angle relative to the first roller to assist in the attraction of the image forming medium to the transfer belt.

Color image forming apparatus having shiftable transfer conveyor belt and attraction assisting roller

A laser beam scanning device including a plurality of laser beam sources for emitting laser beams having properties different from each other, respectively such that each of the laser beams is modulated by an image signal, a deflection member for simultaneously deflecting the laser beams emitted by the laser beam sources, a light detecting member for detecting one of the laser beams such that modulation of the laser beams emitted by the laser beam sources is started in response to a signal outputted from the light detecting member and an optical member which is disposed on an optical path from the deflection member to the light detecting member and optically selects only the one of the laser beams so as to irradiate the one of the laser beams onto the light detecting member.

Laser beam scanning device with plural sources and source-sensitive synchronization

A laser beam scanning apparatus includes plural laser beam sources for emitting laser beams modulated by a picture signal and having different characteristics from each other, a beam composition device for composing the beams emitted from the sources to form one laser beam, a deflecting device for deflecting the composite beam in a main scanning direction, and a beam splitter for splitting the deflected beam on the basis of the characteristic thereof. The apparatus further includes a beam-selecting device for selecting the beam in correspondence with the characteristic of the beam split by the splitter so as to transmit the beam with a specified characteristic and reflect the beam with a characteristic different from that of the transmitted beam.

Laser scanner with selected plural beam sources

An image forming device has a rotating image carrier for carrying an image and a transfer unit including a plurality of rotating rollers, an endless belt travelling around the rollers, and a supporting member for supporting the rollers in such a manner that distances between the rollers be kept constant. At least one of the rollers is a pressure-contacting roller opposed to the image carrier with the endless belt therebetween. The device further has a pressure-contacting unit for energizing the transfer unit in a direction that the pressure-contacting roller be pressure-contacted on the image carrier with the endless belt therebetween.

Image forming device for pressure-contacting an endless belt on an image carrier for image transferring

PURPOSE:To provide the laser beam scanner which eliminates ghosts and can form high-grade images by depositing multilayered dielectric films which selectively allow the transmission of the laser beams separated by a beam splitter and made incident to a light transparent member on the surface of the light transparent member. CONSTITUTION:The laser beams emitted from semiconductor lasers 2, 3 are nearly aligned in the optical axes and are synthesized to one laser beam by a dichroic prism 7. The synthesized laser beam is made incident through a cylindrical lens 8 to a polygonal mirror 9. The laser beam past an ftheta lens 10 is separated to the two laser beams by the beam splitter 11. The multilayered dielectric films 13 and 14 as the optical selecting means of prohibiting the arrival of the beam failed in sepn. by the beam splitter 11 which is the cause for the generation of the ghosts are respectively deposited by evaporation on the inner surface of window glasses 45, 46 to which toners, etc., do not stick.

Laser beam scanner

PURPOSE:To form an image at high speed by providing an energizing means for energizing an endless transfer belt so that it may abut on respective photosensitive bodies, a means for releasing the abutting thereof and a means for stopping the actuation of the photosensitive body. CONSTITUTION:A transfer device 3 is provided with the energizing means 37 for energizing the endless transfer belt 30 so that it may abut on the respective photosensitive bodies 11 and 21 and the releasing means 19 for selectively releasing the abutting thereof. Respective image producing units 1 and 2 are provided with a means 50 for stopping the actuation of the photosensitive bodies 11 and 12 which are released from the abutting. A multicolor image is formed ordinarily by using all the image producing units 1 and 2. When a color mode in which all the image producing units are not used is selected, the abutting of the endless transfer belt 30 on the photosensitive body which is not used is released by the releasing means 50 and the actuation of the photosensitive body is stopped by the actuation stopping means 50. Thus, the image is formed at high speed because only the photosensitive body necessary for forming the image is actuated.

Keizo Nishiguchi

Papers

Laser beam scanning device with plural sources and source-sensitive synchronization

Laser scanner with selected plural beam sources

Image forming device for pressure-contacting an endless belt on an image carrier for image transferring

Laser beam scanner

Multicolor image forming device