Abstract: A laser beam optical scanning device which focuses and scans a laser beam emitted from laser diode 1 in the arrow b direction on a photosensitive drum 40 via focusing lens 3, polygonal mirror 6, and f.theta. lens 7. The scanning laser beam enters a convergence state detector 10, which detects the amount of dislocation of the convergence position. The amount of positional change is calculated to correct the convergence position based on the detected amount of dislocation, and the focusing lens 3 is moved on the optical axis of the lens via motor 21 to correct the beam convergence position. When processing is executed to correct the convergence position in the intermediate zone of the image formign range and the calculated amount of positional change exceeds a limit value, a detection error is assumed, and the focusing lens 3 is moved an amount less than the limit value.

Abstract: A laser beam scanning optical apparatus which images and scans a laser beam emitted from a laser diode on a photo-sensitive drum through a focusing lens, a polygon mirror and an f.theta. lens. An SOS photosensor detects the scanned laser beam and generates a detection signal. The laser diode is controlled to perform pulse emission a specified time after the generation of the detection signal. The pulse beam is incident to a beam detector which adopts a knife edge method, and the amount of a focal shift is detected. The focusing lens is moved along the optical axis in accordance with the detected amount of a focal shift to correct the position of the image point.

Abstract: A laser beam scanning optical apparatus which has Moire fringes generating elements which is located near a position optically equivalent to a scanning surface and modulates a laser beam emitted from a laser source to generate Moire fringes. The Moire fringes generating elements comprises, for example, a first filter which has spatial grating and a second filter which has spatial grating which slants slightly with respect to the spatial grating of the first filter, the first filter and the second filter being arranged upstream and downstream respectively in an optical path. The laser beam scanning optical apparatus further has a light receiving element for receiving the Moire fringes generated by the Moire fringes generating elements. Focusing means for correcting a position of an image point of the laser beam is driven in accordance with an output of the light receiving element.

Abstract: A laser beam scanning optical apparatus which has a laser source unit, a collimator lens, a cylindrical lens, a polygon mirror and a scanning lens with an f.theta. function. The collimator lens is a bifocal lens, and because of the bifocal collimator lens, a part of the laser beam is focused on a point before the surface of a photosensitive member, and another part of the laser beam is focused on a point after the surface of the photosensitive member. Also, the cylindrical lens can be a bifocal lens. In this case, even when the magnification ratio in the sub scanning direction is designed small, the focal length of the cylindrical lens does not have to be lengthened.

Abstract: A copying machine for forming an image by scanning a laser beam which is emitted from an optical system on a photosensitive member. Photosensors are provided at optically equivalent positions to a beginning portion and an end portion of a scanning line on a photosensitive member. A scanning time of a laser beam in the main scanning direction is measured by these photosensors. The measured time and a standard time for a copy magnification set by an operator are compared, and a correction value is calculated, and at the same time, magnification in the main scanning direction is corrected using the correcting value. Also, focusing (adjusting of the beam diameter) is carried out using the photosensors. Each of the photosensors contains a photoelectric transfer element, and a beam which comes through a slit is incident to the element. Each photosensor is provided with two slits. One is perpendicular to the main scanning direction, and the other is inclined to the main scanning direction.

Abstract: A plurality of holding members individually hold some of a plurality of lenses in a scanning optical system. A base member holds and connects a plurality of the holding members at predetermined positional relations with rigidity higher than that of the holding member, and is attached to a structural member of an image forming apparatus.

Abstract: A copying machine for forming an image by scanning a laser beam which is emitted from an optical system on a photosensitive member. Photosensors are provided at optically equivalent positions to a beginning portion and an end portion of a scanning line on a photosensitive member. A scanning time of a laser beam in the main scanning direction is measured by these photosensors. The measured time and a standard time for a copy magnification set by an operator are compared, and a correction value is calculated, and at the same time, magnification in the main scanning direction is corrected using the correcting value. Also, focusing (adjusting of the beam diameter) is carried out using the photosensors. Each of the photosensors contains a photoelectric transfer element, and a beam which comes through a slit is incident to the element. Each photosensor is provided with two slits. One is perpendicular to the main scanning direction, and the other is inclined to the main scanning direction.

Abstract: An illuminating optical system for use in a microfilm reader/printer or the like for illuminating a film comprises an axially symmetric lens system and an anamorphic lens system. The anamorphic lens system includes a condenser lens opposed to a light source. A microfilm reader/printer having such an illuminating optical system causes the axially symmetric lens system to illuminate the microfilm during a reading operation, and the anamorphic lens system to illuminate the film during a printing operation.

Abstract: A laser beam scanning apparatus having a laser beam generating section generating first and second laser beams, a rotatable polygonal mirror for deflecting the first and second laser beams to form scanning lines each extending in a main scanning direction on a beam receiving surface and an optical system for imaging the first and second laser beams deflected by the polygonal mirror on the beam receiving surface. Each of the first and second laser beams impinges on the reflective face of the polygonal mirror at an angle with respect to an optical axis in a sub-scanning direction perpendicular to the main scanning direction. The following condition is satisfied:.vertline..beta..times.tan.theta.a.vertline..ltoreq.(5/3).times.Pi.vertline..beta..times.tan.theta.b.vertline..ltoreq.(5/3).times.Pi.vertline..theta.a.vertline.+.vertline..theta.b.vertline..gtoreq..vertline. .psi.a.vertline.+.vertline..psi.b.vertline.where .beta. is a magnification of the optical system in the sub-scanning direction, .theta.a and .theta.

Abstract: A reading apparatus of the invention has a high resolution reading part, a low resolution reading part, holding means for holding both the reading parts so as to be movable along a document, and means for selecting both the reading parts. The reading apparatus performs by one set of the apparatus total four modes of low resolution reading with respect to a light-impermeable document, high resolution reading with respect to the light-impermeable document, low resolution reading with respect to a large-sized light-permeable document, and high resolution reading with respect to a small-sized light-permeable document, such as a photographic film.

Abstract: An optical device provided in an image forming apparatus and having a laser for emitting a beam, a polygonal mirror for deflecting the beam in a scanning direction, and optical members including an elongated cylindrical lens for directing the deflected beam onto a surface of a photosensitive member. In the optical device, distortion of a scan line of the beam scanned on the surface of the photosensitive member is amended by adjusting the degree of curvature of the cylindrical lens in a plane perpendicular to an optical path.

Abstract: An illuminating optical system for use in a microfilm reader/printer or the like for illuminating a film comprises an axially symmetric lens system and an anamorphic lens system. The anamorphic lens system includes a condenser lens opposed to a light source. The microfilm reader/printer having such an illuminating optical system causes the axially symmetric lens system to illuminate the microfilm during a reading operation, and the anamorphic lens system to illuminate the film during a printing operation.

Abstract: A laser beam composite apparatus which combines more than three beams including a first beam having a first wavelength, a second beam having a second wavelength and polarized in a predetermined direction and a third beam having a second wavelength and polarized in a direction perpendicular to said polarized direction of said second beam. The laser beam composite apparatus combines the first beam and the second beam based on difference of wavelengths thereof and further combines the third beam based on difference of polarized directions thereof.

Abstract: An image reading apparatus of the present invention enlarges and reads a small light-permeable document such as a photographic film. In the apparatus of the present invention, an image of a film is divided into strips and is projected on a part of a main-scanning direction of a line image sensor. The film is then moved in a direction corresponding to the main-scanning direction of the line image sensor, thereby reading the image of the whole area of the film.

Abstract: An illumination device for use in copying apparatus and the like for illuminating an original, the device having an elongated light source and reflecting members each of which is disposed at each side of the optical path from the original to a transmission system for transmitting the image light. The reflecting members reflect the light from the elongated light source toward the vicinity of opposite end portions of the illumination area in the longitudinal direction of the source. The device gives a uniform illumination intensity distribution and achieves a high illumination efficiency with a simple construction.

Abstract: A overhead projector including a projection lens and a deflection mirror for directing the light projected from the lens toward a screen, both the lens and the mirror being individually pivotally movable about horizontal axes parallel to each other and to the original support surface of a stage. The lens is pivotally movable in accordance with variations in the angle of inclination of the mirror and is also pivotally movable with the focusing operation of the lens by an interlocking mechanism. The lens is brought to a proper pivotally moved position by the mechanism according to the angle of elevation and to the focusing operation to project images free of trapezoidal distortion and less of focus.

Abstract: An illumination device for use in a slit exposure system for illuminating a document located on a document table. The illumination device has a light source with an elongated shape and a reflector surrounding a portion of the periphery of the light source and designed to reflect a light emitted from the light source toward the document. The reflector has a plurality of cylindrical reflecting surfaces. Each of the surfaces is designed to reflect while collimating a light virtually emitted from a linear area to be illuminated on the document table toward the light source, assuming that a line from which the light is emitted is located on the linear area.

Abstract: An overhead projector which has a stage for supporting an original thereon comprises an optical system for collecting light to the entrance pupil of a projection lens and a movable mirror for directing light from an illumination light source to an optical system.The movable mirror is movable with the movement of the projection lens parallel to the plane of the stage for placing an original thereon so that trapezoidal distortion and loss of focus which occur when the projection lens projects an image at an oblique angle are avoided. The position for the collection of the illumination light by the optical system is changed according to the movement of the projection lens, and illumination light is always collected at the position of the entrance pupil of the projection lens.

Abstract: A slit exposure type copying machine capable of copying with anamorphic magnification. The degree of the refractive action of at least one triangular prism is so set as to compensate for the difference between the magnification of projection means and the magnification corresponding to the speed of scanning means.