Abstract: A system for laser printing indicia on a moving web has been disclosed, wherein said system comprises an apparatus having one or more laser beam(s) as source(s) of laser energy, a jet of air, an extraction unit and a tunnel with an open entry side and an exit side, and wherein, in the laser marking method, the product flow in the said tunnel is directed from the open entry side to the exit side of the said tunnel; the jet of air, skimming on the laser-impinging surface, from the entrance of the tunnel in the moving direction of the web; and wherein extraction of the product flow is performed at the exit side of the tunnel.

Abstract: A multi-beam scanning optical system includes a plurality of light sources, a deflecting unit which deflects a plurality of laser beams emitted from the light sources, and a scanning optical unit which focuses the laser beams deflected by the deflecting unit onto the surface of a photosensitive member. The scanning optical unit is set such that lateral chromatic aberration is overcorrected. In addition, among angles formed between each laser beam incident on the surface of the photosensitive member and the normal at the surface of the photosensitive member in a sub-scanning direction, the oscillation wavelength of the light source that emits a laser beam forming the minimum angle is set to a value smaller than the oscillation wavelength of the light source that emits a laser beam forming the maximum angle.

Abstract: In an OFS scanning optical system in which a light beam incident to a deflection surface is set to a light beam wider than the deflection surface, angles formed between the center axes of emitted distributions of light beams from light emitting points of respective lasers as light sources and the optical axis of the corresponding optical system within a main scanning section and total angular widths of laser beam radiation angles within the main scanning section are regulated. Thus, symmetry and uniformity of an illumination distribution of an imaging spot on a surface to be scanned are improved.

Abstract: A scanning imaging optical component is used in an optical scanning device which deflects a beam from a light source by a light deflector, condenses the deflected beam toward a surface to be scanned by a scanning imaging optical system, forms a beam spot on the surface to be scanned, and performs optical scanning of the surface to be scanned. The optical component forms at least a part of the scanning imaging optical system, and at least a part of a surface of the optical component other than an effective optical surface is made to be a roughened surface, and roughness thereof is such that: Rmax>0.5 (&mgr;m).

Abstract: An image forming apparatus is provided with photosensitive drums for forming latent images by irradiation of light reflected by a polygon mirror and a fixing device for fixing toner images corresponding to the latent images on a sheet material. Deterioration of an image to be formed is prevented if reflective surfaces of a reflective polyhedron are thinned out in reducing a process speed of image formation. This apparatus is further provided with a control unit for, if the number of surfaces of the polygon mirror is m (where m is an integer of three or more), performing a control for selecting n such that m/(n+1) is not an integer as a relation between m and n and performing a control for making n surfaces unused as a reflective surface of light among continuous n+1 surfaces of the reflective polyhedron in decelerating the image forming process.

Abstract: A printing system has a laser scanner and a print bar such as a page-width-array printhead associated with an array of photodetectors. The scanner scans the array of photodetectors, to selectively light activate photodetectors in the array. Each photodetector, when activated by the scanner triggers its associated inkjet nozzle(s) in the printhead to deposit ink on a media surface. In one embodiment the page-width-array is stationary and the media is periodically advanced as ink drops are deposited.

Abstract: A scanning optical device has a first light source unit for generating a plurality of light beams, a second light source unit for generating at least one light beam, and a deflecting scanner for deflecting by a reflecting surface the light beams generated by the first and second light source units to scan a member to be scanned. The positions of the plurality of laser beams generated by the first light source unit are different from each other in a scanning direction in which the deflecting scanner scans, and the at least one light beam generated by the second light source unit is positioned between the plurality of light beams generated by the first light source unit in the scanning direction.

Abstract: There is provided a scanning optical system, which is provided with a deflector that deflects the plurality of beams, and an imaging optical system that converges the plurality of beams deflected by the deflector to form a plurality of beam spots on surfaces to be scanned, respectively. The imaging optical system has at least one lens whose position is changeable in a plane including an optical reference axis thereof and parallel with the main scanning direction. In this configuration, the imaging optical system satisfies a condition: 0.05<|f/fL|<0.5, where, f represents a focal length of the imaging optical system in the main scanning direction, and fL represents a focal length of the at least one lens in the main scanning direction.

Abstract: Deflection of multiple laser beams, scanning of the photoreceptors by such beams in the main scanning direction and light path separation in the sub scanning direction are carried out by having multiple laser beams strike the same deflecting reflective surface of the deflector at different angles in the sub scanning direction. In order to adjust the incident angles in the sub scanning direction, the angles of the laser beams are simultaneously changed. In order to adjust the incident positions in the sub scanning direction, the laser beams are simultaneously moved in a parallel fashion by a light source adjustment unit.

Abstract: The light beam scanning method and apparatus perform light beam scanning of a cylindrical internal surface scanning type, a cylindrical external surface scanning type, and a plane scanning type, where when a sheet-like object to be scanned is scanned by a light beam emitted from a light source, at least one of lateral displacement and longitudinal displacement of a light beam and aberration in an optical system is compensated by controlling a wave front of the light beam with a wavefront control device. Also, when the lateral displacement, longitudinal displacement, and the aberration are caused by change of an environmental temperature, it is possible to measure the environmental temperature and to perform compensation through the control of the wave front by the wavefront control device based on the measured environmental temperature.

Abstract: A multibeam scanner for scanning an image area with a plurality of laser beams, comprising a plurality of beam emitting points that emit a plurality of laser beams reaching the image area with respective time lags therebetween, a time lag determination unit that determines at least one of the time lags during a predetermined calculation time, a scan controller that controls the plurality of beam emitting points to emit the plurality of laser beams successively in the image area with the at least one of the time lags determined by the time lag determination unit. The multibeam scanner of the invention, comprises a photodetector that detects any one of the laser beams at a predetermined beam detection position. The time lag determination unit determines the time lag between the nth laser beam and the n+1th laser beam.

Abstract: The present invention has an object to provide a highly accurate optical scanner of a simple construction which permits reduction of jitter caused by a division error of the deflection surface of a polygonal deflector, and to provide a color image forming apparatus using the same. The optical scanner of the invention comprises a plurality of scanning units each having a polygonal deflector onto which a flux emitted from a light source is directed, and a scanning optical system which forms the flux reflection-deflected by the polygonal deflector into spots on a surface to be scanned. In the optical scanner of the invention, two or more scanning units commonly use a single polygonal deflector.

Abstract: An image forming apparatus comprises: a plurality of image forming means 7 arranged along a line, which include image carriers and developing means for developing latent images formed on the image carriers, respectively; and an exposure means 6 which emits laser beams for exposure to form latent images on the respective image carriers, wherein the exposure means 6 comprises a plurality of laser beam sources to be modulated according to image data corresponding to the image carriers 17, a common polygon mirror 21 which is arranged horizontally or vertically and in which laser beams from the laser beam sources are reflected at a common reflection facet of the polygon mirror 21 and are thus deflected, and optical paths for deflecting the laser beams in non-parallel with each other toward the respective image carriers 17.

Abstract: A light scanner has a light source 1 of a two-dimensional array consisting of a plurality of light source elements, a coupling lens system 2 for collimating a light flux from the light source 1, a shaping lens system (cylindrical lens 4 and lens 5) for shaping the light flux, light beam deflection means 6 for deflecting and scanning the post-shaped light flux, and a scanning lens system 7 for forming an image of the deflected and scanned light flux on a scanned medium 8. Assuming that the focal length of the coupling lens system 2 is f, a slit 3 for limiting the subscanning direction width as a member for shielding a part of the light flux is placed at a location at a distance of about f from the coupling lens system 2 in an opposite direction to the light source 1.

Abstract: Provided is an optical scanning apparatus in which images are formed precisely on the target surface to be scanned with a plurality of beams and low manufacturing cost is realizes. The optical scanning apparatus comprises four light sources, each of which emits a beam, a collimator lens and a polygon mirror. Provided between the polygon mirror and the target surface, cylindrical mirrors to form images with beams on the respective target surfaces. The optical path, from the polygon mirror to the target surface, of the beams emitted from the light sources away from the optical axis of the collimator lens is shorter than the corresponding optical path of the beams emitted from the light sources close to the optical axis. Thus, even though the collimator lens has the curvature of field, all of the image spots formed with the beams are located just on the target surface.

Abstract: A multibeam scanner including a light source for emitting a plurality of light beams, a deflector for deflecting the plurality of light beams emitted from the light source, and a scanning optical system for guiding the plurality of light beams deflected by the deflector to a scan surface. A first light shielding member for determining one end of the diameter of at least one of the plurality of light beams and a second light-shielding member for determining the other end of the diameter of the at least one of the plurality of light beams are disposed apart from each other in a direction in which the light beams propagate and between the light source and the deflector. The first light-shielding member and the second light-shielding member are used to limit the diameter of the at least one of the plurality of light beams.

Abstract: There are provided a compact scanning optical apparatus optimal for high-definition image recording, which is able to uniformize the spot size in the sub-scanning direction in an effective scanning area, and an image-forming apparatus using it.

Abstract: An object of the present invention is to provide a scanning optical apparatus that is capable of suppressing, to a minute amount, scanning line bending caused by rotational decentration of a single lens that is a scanning optical system, and to provide an image forming apparatus using the optical scanning apparatus. To achieve the stated object, with the technique of the present invention, a single lens is used as a scanning optical system and the surface shape of the single lens is set so that a direction of scanning line bending in the sub scanning direction occurring when an incident surface of the single lens is rotationally decenter about an axis parallel to the main scanning direction is opposite to a direction of scanning line bending in the sub scanning direction occurring when an exit surface is rotationally decenter about the axis parallel to the main scanning direction.

Abstract: A multi-beam scanning optical system includes a plurality of light sources, a deflecting unit which deflects a plurality of laser beams emitted from the light sources, and a scanning optical unit which focuses the laser beams deflected by the deflecting unit onto the surface of a photosensitive member. The scanning optical unit is set such that lateral chromatic aberration is overcorrected. In addition, among angles formed between each laser beam incident on the surface of the photosensitive member and the normal at the surface of the photosensitive member in a sub-scanning direction, the oscillation wavelength of the light source that emits a laser beam forming the minimum angle is set to a value smaller than the oscillation wavelength of the light source that emits a laser beam forming the maximum angle.

Abstract: An optical scanning apparatus has an incident optical system for causing a light beam from a light source to be obliquely incident in a sub-scanning cross-section on a deflecting surface of an optical deflector, and an imaging optical system for forming, on a scanned surface, an image of the light beam deflected by the deflecting surface.

Abstract: Provided are a multi-beam scanning optical system capable of implementing high-quality printing in relatively simple structure and at high speed, and an image forming apparatus using it. The multi-beam scanning optical system has an incidence optical unit for guiding a plurality of beams emitted from a light source unit having a plurality of light-emitting regions spaced apart from each other in a main scanning direction, to a deflector; a scanning optical unit for focusing the plurality of beams deflected by the deflector, on a surface to be scanned; and a synchronism-detecting optical unit for converging part of the plurality of beams deflected by the deflector, via a return mirror on a slit surface by a lens section, thereafter guiding the beams to a synchronism detector, and controlling timing of a scan start position on the surface to be scanned, by use of a signal from the synchronism detector.

Abstract: A multibeam scanning optical system includes a light source unit having a light source and a plurality of beam converting elements having a first optical system for converting a beam emitted from the light source into a divergent beam or a convergent beam, beam combining element for combining a plurality of divergent beams or convergent beams emerging from the light source unit, and causing them to emerge substantially in the same direction, a second optical system for causing the plurality of divergent beams or convergent beams combined by the beam combining element to be imaged as a linear image long in the main scanning direction, deflector having a deflecting surface at or near the imaging position of the second optical system, and for reflecting and deflecting the plurality of incident divergent beams or convergent beams in the main scanning direction, and a third optical system for causing the plurality of divergent beams or convergent beams reflected and deflected by the deflector to be imaged on a sur

Abstract: Provided are a multi-beam scanning optical system capable of implementing high-quality printing in relatively simple structure and at high speed, and an image forming apparatus using it. The multi-beam scanning optical system has an incidence optical unit for guiding a plurality of beams emitted from a light source unit having a plurality of light-emitting regions spaced apart from each other in a main scanning direction, to a deflector; a scanning optical unit for focusing the plurality of beams deflected by the deflector, on a surface to be scanned; and a synchronism-detecting optical unit for converging part of the plurality of beams deflected by the deflector, via a return mirror on a slit surface by a lens section, thereafter guiding the beams to a synchronism detector, and controlling timing of a scan start position on the surface to be scanned, by use of a signal from the synchronism detector.

Abstract: An optical scanning apparatus is configured to comprise (a) a deflector for deflecting and scanning a plurality of bundled incident laser beams, (b) a conversion optical system for converting the bundle of laser beams moving at a constant angular velocity into a bundle of laser beams moving at a constant linear velocity, (c) reflection mirrors for separating the bundled laser beams into four corresponding to respective colors, (d) photosensitive members for forming respective electrostatic latent images by means of the laser beams corresponding to the respective colors, wherein one of the photosensitive members is disposed on a plane parallel to an area defined by the laser beams traveling between the deflector and the conversion optical system and (e) a correction optical system for correcting curvatures of field with respect to the respective laser beams and leading the laser beams to the photosensitive members.

Abstract: Provided are a multi-beam scanning optical apparatus capable of realizing compactification of a synchronism-detecting optical system and high-accuracy synchronism detection based on prevention of spatial overlap between spots, and an image forming apparatus using it.

Abstract: Scan systems include at least one radiation source for directing at least one beam toward a scan-device system. The scan device system includes at least one scan device that reflects these beams as rotating scan beams which point to the optical aperture of a rotating optical system. The rotating optical system has at least one optical component selected from a group of reflectors and lenses, focuses the scan beams into radiation spots, and projects them onto a scanned surface as moving scan spots. Linear relative movement between the scanned surface and the rotating optical system produces an area scan of inner drum or planar surface.

Abstract: Disclosed is a color image forming apparatus in which it is possible to prevent positional deviation in scanning of each optical scanning device without having to improve the lens accuracy to an extreme degree.

Abstract: An optical scanner assembly in which a pair of F&thgr; lenses are arranged symmetrically across a single deflector means and a reflector for introducing a light beam from at least one of a plurality of light sources to the deflector means is arranged on the side opposite to that light source with respect to an axis of symmetry of the F&thgr; lenses so that the optical path up to the reflector crosses the axis of symmetry, thereby securing the optical path length from the light source to the deflector for the miniaturization of the optical scanner assembly and allowing easy adjustment for equalizing the optical path lengths of all the light sources.

Abstract: An optical scanning apparatus includes a light source having a plurality of light-emitting portions arranged as inclined with respect to a main scanning direction, a deflector for deflecting a plurality of light beams emitted from the light source, an imaging system for guiding the plurality of light beams deflected and reflected by the deflector, onto a scanned surface, a detector arranged substantially at the same position as the scanned surface and in a normal direction to the main scanning direction. The detector detects scanning positions of the plurality of light beams and a difference between pass times of the plurality of light beams to thereby detect deviation of the scanning positions and variation of magnification of the optical scanning apparatus. A correcting device is provided for correcting drawing positions of the plurality of light beams on the scanned surface, based on the result of detection by the detector.

Abstract: A polygonal scanner of the present invention includes a rotary body including a ceramic rotary sleeve and a metallic cylindrical member shrinkage-fitted on the rotary sleeve. The cylindrical member is formed with mirror surfaces constituting a polygonal mirror. A dynamic pressure, air bearing supports the rotary body. The mirror surfaces overlap the rotary sleeve in the axial direction of the rotary sleeve. A hole greater in diameter than the dynamic pressure, air bearing is formed in the top wall of the cylindrical member. The cylindrical member includes a stress removing portion positioned between the mirror surfaces and the rotary sleeve for removing a stress ascribable to shrinkage-fitting.

Abstract: An optical scanning apparatus includes two light sources, two beam shaping mechanisms, a light deflector, and two scanning beam focusing mechanisms. The light source emits a light beam. The beam shaping mechanism shapes the light beam. The light deflector deflects each light beam in a continuously changing direction thereby converting each light beam into a scanning light beam. The scanning beam focusing mechanism brings the scanning light beam to a focus on a photoconductive surface, and satisfies an equation of &Dgr;L cos &agr;>R/2 at a junction of the scanning light beam with the other scanning light beam on the photoconductive surface, wherein &Dgr;L represents an inherent light pass length variation, &agr; represents an incident angle, and R represents an inherent marginal distance.

Abstract: In a deflection scanning apparatus used for a laser beam printer or the like, a rotating body is provided with a deflector which has a plurality of recesses arranged in a concentric manner with the center at the rotation axis of the rotating body. Balance weights are set in the recesses so as to remove rotation unbalance in rotation of the rotating body.

Abstract: A multi-beam scanning optical system is provided with a plurality of light sources that emit a plurality of laser beams having different wavelengths, respectively, a single deflector which deflects the plurality of laser beams simultaneously, an imaging optical system that converges the plurality of laser beams deflected by the single deflector on the surface to be scanned, lateral chromatic aberration of the imaging optical system being compensated, and a beam detector that receives the plurality of laser beams directed to outside the predetermined imaging area, a synchronizing signal being generated upon detection of each of the plurality of light beams by the beam detector. Further, the scanning optical system includes a dispersion element inserted in optical paths of the laser beams directed to the beam detector, the dispersion element being configured such that the laser beams directed to the beam detector are shifted in the scanning direction.

Abstract: A multi-beam scanning optical system is provided with light sources that emit a plurality of laser beams having different wavelengths, respectively, a single deflector which deflects the plurality of laser beams simultaneously, an Imaging optical system that converges the plurality of laser beams deflected by the single deflector on the surface to be scanned, and a beam detector that receives the plurality of laser beams directed to outside of the predetermined imaging area via at least one of lens elements included in the imaging optical system, a synchronizing signal being generated upon detection of each of the plurality of light beams by the beam detector. It should be noted that an optical characteristic of the imaging optical system is configured such that the laser beams directed to the predetermined imaging area are aligned in a scanning direction, while the beams directed to the beam detector are shifted in the scanning direction.

Abstract: When a printer receives print data in the form of PDL, commands are analyzed and intermediate data is stored in a page buffer (102). Rotation of a polygon mirror is started at this time by a scanner pre-rotation command unit (107), after which bitmap data is expanded by a bitmap expanding processing unit (103) and printed. When printing starts, the polygon mirror is already rotating. This makes it possible to shorten first-page discharge time.

Abstract: In an optical scanning device of the present invention, a plurality of light sources emit a plurality of light beams. An optical system has a rotary polygonal mirror deflecting the light beams from the light sources, the optical system focusing the deflected light beams onto a scanned surface to form light spots thereon, the scanned surface being optically scanned with the light spots by a rotation of the rotary polygonal mirror. A light-amount monitoring unit monitors respective amounts of the light beams emitted by the light sources. A control unit controls the respective amounts of the light beams emitted by the light sources, based on detection signals output from the light-amount monitoring unit.

Abstract: A multi-beam scanning device is provided with a plurality of light sources that emit a plurality of light beams, respectively, a scanning system that deflects each of the plurality of light beams to scan within a predetermined scanning range, a modulating system that modulates the plurality of light beams at a plurality of frequencies, respectively, and a beam detector positioned with in the scanning range to receive the plurality of light beams respectively modulated at different frequencies. The beam detector outputs a signal representing intensity of received light beams. A separating system is provided to separate the output signal of the beam detector, on a basis of the plurality of frequencies, into a plurality of component signals, and a synchronizing signal generating circuit that generates a plurality of synchronizing signals respectively corresponding to the plurality of light beams based on the plurality of component signals.

Abstract: A multi-beam scanning optical system is provided with a plurality of laser diodes respectively emitting a plurality of laser beams, each of said plurality of laser diodes being accommodated in a casing, and a laser diode holding unit that holds the casings of the plurality of laser diodes. Heat generated by each of the plurality of laser diodes is conducted to each other through the casings of the plurality of laser diodes and the laser diode holding unit.

Abstract: An optical scanning device according to the present invention includes a lens to convert divergent rays from a laser diode to parallel or convergent rays, a slit to regulate luminous energy of the parallel or convergent rays, a before deflection optical system having lenses with different power for main-scanning and sub-scanning, optical scanning means to scan objects to be scanned with the parallel or convergent rays, and an imaging optical system for imaging on the objects to be scanned by passing the scanned rays with the optical scanning means, the slit of the before deflection optical system has an opening with a larger diameter than a 13.5% diameter of the optical intensity of the rays in at least one direction of the main-scanning and the sub-scanning directions. Thereby, it may be possible to reduce the sidelobe, and to control density irregularities of exposed images.

Abstract: A multi-beam scanning apparatus includes a light source having a semiconductor laser chip in which a plurality of light emitting points are arranged such that optical beam spots are impinged at predetermined intervals in a sub-scanning direction on a surface to be scanned. A light receiving element receives a light flux from the semiconductor laser chip for monitoring the light. A case houses therein the semiconductor laser chip and the light receiving element, and has an opening for transmitting the light emitted from a surface of the semiconductor laser chip. A coupling lens couples a divergent light flux from the light source with a subsequent system. A deflector deflects the light flux. A first imaging system arranged between the coupling lens and the deflector has a power in the sub-scanning direction so as to transform the light flux from the coupling lens into a substantially linear image in a vicinity of a deflecting surface of the deflector.

Abstract: A scanning unit of a laser printer in which a cover is provided on a scanning motor so that the scanning motor is isolated from an outside and an inner portion of the cover is maintained in a vacuum state, and in which the scanning motor is provided with a magnetic bearing having a repulsive force in thrust and radial directions, and a magnetic bearing apparatus used in the scanning unit, whereby the noise is lowered and the structure of the scanning unit can be simplified.

Abstract: There is proposed a method and apparatus for multibeam scanning an inner face of a cylindrical drum, in which scanning lines are straightened under a simple control, and an interval between the scanning lines can be easily changed, thereby simplifying a constitution. In an embodiment, while keeping an interval between two light beams projected to an optical scanning system, the light beams are one-dimensionally deflected in mutually orthogonal directions in synchronism with a rotation of the spinner, respectively. In a second embodiment, one light beam is projected along a central axis common with the spinner and the cylindrical drum to the spinner. The other light beams are inclined in a plane including the central axis by a constant angle &phgr;y separately predetermined for each of the other light beams, and further inclined in a direction orthogonal to the plane including a rotation axis by an angle &phgr;x which is determined in synchronism with a rotation angle &thgr; of the spinner.

Abstract: A multi-beam scanning optical system includes a light source having a plurality of light-emission points, an incident optical system for guiding a plurality of light beams emitted from the light source to a deflector, a scanning optical system for forming the plurality of light beams reflected/deflected by the deflector into images on a scanned surface, and a synchronization detection device in which a part of the plurality of light beams from the deflector are reflected at a predetermined angle in a sub-scanning cross-section by using a mirror to be scanned on a surface of a slit member and to be guided to a surface of a synchronization detection element via the slit member, and a timing at a scanning start position on the scanned surface is controlled by using a signal from the synchronization detection element. The slit member is positioned such that a plurality of light beams scanned on a surface of a slit opening are substantially vertically scanned on the slit opening.

Abstract: A multi-beam laser exposure unit of the present invention includes a light beam deflector for deflecting a light beam in a predetermined direction, a plurality of laser devices, a pre-optical system, including a glass lens and a plastic lens, for converting a cross sectional shape a of light beam emitted from the respective laser devices to a predetermined shape, and a post-deflection optical system, including two lenses for image-forming each light beam deflected by the deflector to be scanned on a predetermined image surface at a uniform speed. The power of the two lenses of the post-deflection optical system is defined to be positive in a direction parallel to a rotational axis of reflective surfaces of the deflector. Also, at least one lens surface of these lenses is formed not to include a rotational symmetrical surface.

Abstract: An object of the present invention is to provide an image forming apparatus that has a light source, deflecting device for deflecting light emitted from the light source by a rotation, a mirror for deflecting the light deflected by the deflecting device, an image bearing body to which the light deflected by the mirror is irradiated, and a lens for image-forming the light deflected by the deflecting device onto the image bearing body, wherein a plurality of lights are deflected by the one deflecting device and only the one mirror exists in an optical path along which the one light deflected by the deflecting device reaches the image bearing body.

Abstract: Disclosed is a color image forming apparatus in which it is possible to prevent positional deviation in scanning of each optical scanning device without having to improve the lens accuracy to an extreme degree.

Abstract: An image forming apparatus includes a laser beam scanning unit adapted for scanning laser beams on a surface of a charged image bearing member (5). The laser beam scanning unit (53) comprises a semiconductor laser array (21) having a plurality of light emitting portions (21a) and a rotating polygon mirror adapted for deflecting laser beams emitted from the light emitting portions to the image bearing member (5). The light emitting portions (21a) are disposed two-dimensionally on a surface of the semiconductor laser array. The lighting and the amount of light of the light emitting portions (21a) are discretely controlled by a control unit. The scanning unit further includes a collimator lens having a focal length fc, where a distance between a most spaced two of the plurality of light emitting portions is .delta. max, and fc/.delta. max is 25 or more.

Abstract: A multi-beam scanning optical system is provided with a light source unit emitting a plurality of beams. The beams are incident on a polygonal mirror, and deflected thereby to scan in a predetermined scanning range. The scanning beam is incident an f&thgr; lens system. The f&thgr; lens system includes a plurality of lenses, and all the beams pass at least one of the plurality of lenses included in the f&thgr; lens system. The lens, which all the beams pass through, is formed as a single lens element made of single material. Further, the lens contributes to convergence of the beams in the main scanning direction.

Abstract: A multi-beam scanning apparatus performs image scanning by emitting multiple beams from a plurality of light sources, which beams are deflected by a common deflector at equiangular velocity. The beams are then condensed by a common scanning image forming lens so as to form optical spots on a scanning surface. As a result, the plurality of lines are simultaneously scanned by the beams on the scanning surface at a substantially constant velocity. Characteristics of the light sources, such as the wavelength thereof, and other factors such as writing density and desired writing width of a writing line, are arranged to eliminate differences in a written vertical line in a sub scanning direction caused by a magnification difference, regardless of the cause of such differences. In addition, the modulation frequency of the plurality of light sources is made different from each other so that writing widths of the dots written by the plurality of light sources become the same.

Abstract: A multi-beam optical scanner, in which a lateral magnification &bgr; in a composite system of an optical system between the light source for a multi-beam and the scanned surface satisfies the condition: 2<&bgr;≦8.5, and a plurality of light spots on the scanned surface execute optical scanning of the scanning lines adjacent to each other.