Seiko Epson Corporation

Seigo Epson Corporation

Kyu Takada

Nozomu Inoue

Yujiro Nomura

Takashi Hama

Yoshiro Koga

Takashi Suzuki

Hajime Kurihara

Takeshi Sowa

Yujirou Nomura

A multi-beam optical scanner includes shaping optics ( ) by which a plurality of light beams issued from light emitting portions ( ) are shaped to be substantially parallel in a primary scanning direction, a deflector having reflecting faces ( ) that reflect and deflect the plurality of light beams and scanning optics ( ) by which the plurality of light beams reflected and deflected by the reflecting faces ( ) are scanned across a plane ( ) to be scanned as a plurality of adjacent beam spots, wherein the distance from the rear principal plane of the shaping optics ( ) to the front principal plane of the scanning optics is expressed by f &plus;f , where f and f are the focal lengths of the shaping optics ( ) and the scanning optics ( ), respectively, in the primary scanning direction.

Optical scanner

An improved optical scanning apparatus is adapted to be such that at either end of the scan range, an optical beam deflected by a reflecting surface of a scanner will pass through an anamorphic lens in scanning optics at a position spaced from its optical axis in the sub-scanning direction. The anamorphic lens has such a sectional profile in the sub-scanning direction that the lens thickness at one end of the sub-scanning direction differs from the thickness at the other end. Also, a high speed optical scanning apparatus based on the dual incidence and the oblique incidence, can prevent a positional variation of a scanning line that is due to a shift of each facet of the rotating polygonal mirror, which is caused by an offset of the rotating axis of the rotating polygonal mirror. The scanning apparatus includes a light source, a rotating polygonal mirror with a plural number of reflecting surfaces for reflecting and deflecting an optical beam emitted from the light source, transfer optics for receiving the optical beam that is reflected and deflected by a first reflecting surface of the rotating polygonal mirror and transferring the optical beam to a second reflecting surface of the mirror, and scanning optics for scanning a scanned surface with the optical beam that is reflected and deflected by the second reflecting surface.

Optical scanning apparatus

An image forming apparatus includes a laser beam scanning unit adapted for scanning laser beams on a surface of a charged image bearing member (,). The laser beam scanning unit (,) comprises a semiconductor laser array (,) having a plurality of light emitting portions (,) and a rotating polygon mirror adapted for deflecting laser beams emitted from the light emitting portions to the image bearing member (,). The light emitting portions (,) are disposed two-dimensionally on a surface of the semiconductor laser array. The lighting and the amount of light of the light emitting portions (,) 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.

Image forming apparatus

To provide an optical scanner for typical use with laser beam printers that is capable of effective correction of aberrational characteristics and which also produces a constant beam spot size, a semiconductor laser array 1 having a plurality of light-emitting portions issues a plurality of beams, which are reflected and deflected by reflecting surfaces of rotating polygonal mirror 5 and pass through imaging lens 6 to form a plurality of beam spots on the surface to be scanned 7. Both the entrance and exit surfaces of imaging lens 6 are such that the curvatures in the sub- and main scanning directions are independent of each other, with the curvature in the sub-scanning direction varying continuously in the main scanning direction over the effective area of imaging lens 6.

An optical scanner that has a simple construction and which yet exhibits satisfactory imaging performance under varying temperature conditions. Of the two orthogonal scanning cross sections of scanning optics (i.e., the main and sub-scanning cross sections), the one that involves the greater movement of the image plane due to the temperature-dependent changes in optical characteristics (e.g. the variation in the operating wavelength of a light source, the index variation of a lens material and the thermal expansion of a lens itself) is adapted to be the same as the other cross section that involves the greater movement of the image plane due to the change in the distance from the light source to a collimator lens. If necessary, additional correction is effected in such a way that the scanning cross section that involves the greater overall movement of the image plane after correction for temperature changes is adapted to be different from the cross section that involves the greater amount of optical field curvature.

A laser beam scanning unit (53) adapted for scanning laser beams on a surface of a charged image bearing member (5) is provided. The laser beam scanning apparatus (53) comprises a semiconductor laser array (21) having a plurality of light emitting portions (21a) and a rotating polygon mirror (3) 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 (60).

Laser beam scanning image forming apparatus having two-dimensionally

An optical scanner for use in laser beam printers and the like which is particularly satisfactory in imaging characteristics. A light beam from a semiconductor laser passes through a collimator lens, an aperture diaphragm and a cylindrical lens. The beam is then deflected by a rotating lens mirror and subjected to the focusing action of an imaging lens so that it is focused to form a beam spot, which scans over a scan surface as the beam is deflected. The imaging lens has aspheric surfaces in the main-scanning cross section and is designed so that the rate of change in its curvature and other relevant parameters satisfy a predetermined equation so as to lie within a predetermined range.

The improved beam scanning apparatus has an optical element that is driven to rotate by means of a drive means so as to be capable of continuous angular displacement with respect to the beam from a light source. The optical element deflects the incident beam so that it is focused to form image on the image plane. It is provided with an entrance face, a reflecting face and an exit face which have their shape specified in such a way as to achieve effective correction of aberration, provide higher resolution, and reduce the size and cost of the apparatus.

Beam scanning apparatus, for providing tilt correction to a rotary

An optical scanner comprises: a light source; beam shaping optics for transforming an optical beam from the light source into a convergent beam; a rotating polygonal mirror having at least a first reflecting face for deflecting the convergent beam and a second reflecting face; and transmission optics having a lens, with which the optical beam deflected by the first reflecting face of the rotating polygonal mirror is allowed to be incident on the second reflecting face of the rotating polygonal mirror, with the optical beam incident on the second reflecting face of the rotating polygonal mirror being deflected therefrom to produce a scanning optical beam which scans a predetermined surface to be scanned, wherein the convergent optical beam forms a focused image at a point located between the first reflecting face of the rotating polygonal mirror and the lens in the transmission optics.

An image forming apparatus including an image bearing member, a charging unit, a laser beam scanning apparatus and a developing unit. The laser beam scanning apparatus includes a semiconductor laser array for emitting laser beams, a collimator lens for collimating the beams, a rotating polygon mirror for deflecting the beams collimated by the lens, and an aperture stop between the laser array and the mirror. The following relations between the aforementioned elements of the apparatus are satisfied: ##EQU1## where f is a focal length of the collimator lens; s is a distance between a focal point on a mirror side of the collimator lens and the aperture stop; t is a distance between one of the light emitting portions that is spaced farthest, relative to others of the light emitting portions, from the optical axis; D is a diameter of the aperture stop, and d is a diameter of each of the laser beams collimated by the collimator lens.

Image forming apparatus including a plural laser beam scanning apparatus

To enable scanning by a light beam with a single unit of rotating optics, a light beam issuing from semiconductor laser 1 is launched into rotating lens mirror 3 through entrance face S.sub.1, thence directed to reflecting face S.sub.2, whereby it is deflected to leave the lens mirror 3 through exit face S.sub.3 and form a spot that scans over the imaging plane.

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Nagano, Japan

Kyu Takada