Abstract: An apparatus and method for controlling the modulation of an exposing beam of a rotating polygon type image forming apparatus using control marks formed on a rotating surface portion of a polygon member or a motor polygon assembly. The control marks are read by a reader during rotation of the polygon member, and the information read from the control marks is used to control the modulation of the exposing beam of the image forming apparatus to expose evenly spaced, uniformly sized, precisely oriented, geometrically straight scan lines of pixels on a photosensitive member. The control marks can include pixel clock information, intensity correction information, error correction information about individual facets of the polygon member, and motor speed control information.

Abstract: An optical scanning apparatus includes a semiconductor laser, a polygonal mirror as a deflector for scanning a light beam from the laser, a photosensitive drum for forming an electrostatic latent image, a converging lens for converging the light beam from the laser onto the photosensitive drum, and a reflection mirror located between the deflector and the photosensitive drum. The reflection mirror is adapted to reflect the light beam so that a light beam reflected by the reflection mirror is used to read a source document placed at a position that is the conjugate of the position of the photosensitive drum surface with respect to the converging device. Inside the casing of the semiconductor laser are a beam splitter for light path separation and a photosensor. The apparatus has an image reader section and a laser printer section, which share a common optical system, thus providing a compact design and cost reduction and also equalizes the accuracy of image reading and printing.

Abstract: A synchronizing signal generating circuit for an optical scanning device. The synchronizing signal gernerating circuit including a photodiode, a high-pass filter circuit, and a signal processing circuit. The high-pass filter circuit is the load for the photodiode and is comprised of an inductance and a resistance arranged in parallel. The high-pass filter circuit is configured to have a cutoff frequency that is marginally below the frequency of a synchronizing signal. The signal processing circuit is connected to the connection point of the photodiode and the high-pass filter circuit and receives a detection signal. The signal processing circuit amplifies the detection signal, cuts the DC component, and compares the resulting signal to a reference voltage to produce the synchronizing signal.

Abstract: A scanning optical system having both a reading optical system and an image forming optical system is capable of using one or more components for both systems.

Abstract: An output writer includes an output scanner and optics that creates printed pixels along curved scan paths. Provided that a source of input image pixel value data presents data with pixels to be positioned in a rectangular coordinate system with a constant distance in an x-direction between adjacent input pixels, a position is determined along the curved scan paths of a pixel to be printed. The difference between the position of the pixel to be printed and the positions in the rectangular coordinate system of associated input pixels is determined, and then a value for the pixel to be printed is determined as a function of (1) the value data of the associated input pixels and of (2) the determined difference between the position of the pixel to be printed and the positions of the associated input pixels.

Abstract: A raster output scanner data controller reads pixels of an image from an image memory and outputs serially pixel data streams to a raster output scanner. The data controller includes an image memory storing a plurality of pixel data blocks in a scan line order, an image memory controller coupled to the image memory, a plurality of first-in, first-out memories coupled to the image memory controller for storing pixel data blocks corresponding to a plurality of beams, and an image controller coupled to the plurality of first-in, first-out memories. The pixel data blocks are transferred from the image memory to the plurality of first-in, first-out memories. The image controller reads the pixel data blocks from the plurality of first-in, first-out memories, converts the pixel data blocks read from the plurality of first-in, first-out memories into a plurality of pixel data streams and outputs the plurality of pixel data streams to the raster output scanner.

Abstract: The present invention provides a method for making a lithographic printing plate from an original containing continuous tones comprising the steps of:frequency modulation screening said original to obtain screened dataimage-wise exposing according to said screened data an imaging element comprising in the order given on a hydrophilic surface of a support (i) an image receiving layer containing physical development nuclei, (ii) a photosensitive layer containing one or more silver halide emulsions being in water permeable relationship with said image receiving layerapplying an aqueous alkaline solution to the imaging element in the presence of (a) developing agent(s) and (a) silver halide solvent(s),treating the imaging element to remove the layer(s) on top of said image receiving layer, thereby uncovering said silver image formed in said image receiving layer,characterized in that said aqueous alkaline solution is substantially free from thiosulphate ions and bromide ions and contains an aminoalcohol in an amo

Abstract: A facsimile apparatus receives image information and recording the image information by use of a laser-beam printer. In a case where the document size of the received image information is larger than the size of the recording paper, the recording resolution of the laser-beam printer in each of main-scanning and sub-canning directions is changed and set, and recording of the received image information is performed at the set resolution.

Abstract: A raster scanner characterized in that at least one reflecting mirror is supported by a movable supporting mechanism in a manner capable of moving along an incident optical axis while being kept in a certain angle attitude or that an optical sub-frame provided with a beam generating means, a beam deflecting means and an imaging lens is supported by a movable supporting mechanism in a manner capable of moving along an output optical axis while being kept in a certain angle attitude to be able to avoid assuredly an occurrence of unbalance in image widths in the main scan direction at both ends of the image when length of optical path is adjusted. This invention also presupposes that the reflecting mirror is a cylindrical mirror. Angle adjusting performance of the cylindrical mirror is kept in good condition by rotating one end portion of the cylindrical mirror following to a rotation of the other end portion of the same centering on an axis parallel to a generating line of the cylindrical mirror.

Abstract: An image forming apparatus includes a scan unit for scanning a light beam modulated based on an image signal in the main scan direction, and a drive unit for rotating an image carrier in the subscan direction of an image. The rotation period of the image carrier is set to be an integer multiple of the scan period in the main scan direction of the light beam by the scan unit.

Abstract: There is provided a method for making a lithographic printing plate according to the DTR-process from a printing plate precursor comprising on a hydrophilic surface of a support in the order given a layer of physical development nuclei and a silver halide emulsion layer from an original containing continuous tones comprising the steps of:frequency modulation screening said original to obtain screened data,image-wise exposing said printing plate precursor according to said screened data,developing a thus obtained image-wise exposed lithographic printing plate precursor by means of an alkaline processing solution in the presence of a developing agent and a silver halide solvent yielding a lithographic printing plate, characterized in that the frequency modulated halftone dot with the greatest main dimension on said lithographic printing plate has a main dimension of more than 21 .mu.m.

Abstract: A modulated writing light beam (18) having a wavelength to which an imaging element (33) is sensitive and a reference light beam (46) having a wavelength to which the imaging element (33) is insensitive are generated and simultaneously directed to a moving optical device (22) to cause the writing light beam (18) to scan across the surface of the imaging element (33) in a first scanning direction (C) and the reference light beam (46) to scan across the surface of a light detecting element (50) in the first scanning direction (C) to generate signals indicative of the position of the writing light beam (18) on the surface of the imaging element (33). The writing light beam (18) is modulated and the imaging element (33) is moved in a second scanning direction (B) in response to the signals generated by the light detecting element (50). Thereafter the exposed imaging element (33) is processed to prepare a lithographic printing plate.

Abstract: A scanning optical system having an image forming optical system for emitting a scanning beam modulated in accordance with image information onto a destination surface. The scanning optical system further includes a reading optical system for receiving light reflected from an object surface to obtain image information from the object surface. Both systems make use of at least one common optical component, for example, a polygonal mirror, a cylindrical mirror, a common optical path or a toric lens.

Abstract: In an image forming apparatus for simultaneously recording plural image lines on a recording medium by scannintg simultaneously with plural light beams along parallel scanning lines in a primary scanning direction, before a deviation detector detects a deviation among the plural light beams in the primary scanning direction, a beam power controller adjusts the electric power for each light beam generator so that the beam diameter of each light beam is made equal to each other.

Abstract: A raster scanning system is disclosed which utilizes a post polygon optics which generates a field curvature to substantially reduce a differential bow. The post polygon optics of this invention comprises a first lens, a second lens and a wobble correction mirror. The second lens and the wobble correction mirror generate a field curvature to reduce the differential bow and the combination of the first lens, second lens and the wobble mirror correction minimizes the generated field curvature.

Abstract: The raster scanning system of the present invention includes a beam generator which generates a beam of radiant energy in response to a drive signal. The drive signal comprising a series of pulses. The raster scanning system further includes a polygon having an overfilled facet design in which a plurality of facets are at least partially positioned in the optical path of the beam of radiant energy regardless of the rotational position of the polygon. The polygon being adapted to scan a spot across a beam receiving surface. Additionally the raster scanning system includes spot size correcting means for maintaining a constant spot size of the scanned spot by modulating the pulse width of the drive signal provided to the beam generator.

Abstract: An image read-out and reproducing apparatus comprises a sub-scanning device for supporting an image storage sheet, on which image information has been recorded, and a recording material, on which an image is to be reproduced during its exposure to a light beam, such that the image storage sheet and the recording material may stand side by side with each other. The sub-scanning device conveys the image storage sheet and the recording material in the same direction or in directions opposite to each other. A single main scanning device causes a light beam to scan the image storage sheet and the recording material in a direction, which is approximately normal to the direction or directions along which the image storage sheet and the recording material are conveyed, and with a scanning width that covers both the image storage sheet and the recording material.

Abstract: A single photodetecting element, in front of which a knife edge is placed, is disposed in front of a scanning surface and outside a laser beam scanning region for the scanning surface. Two mirrors or a single half mirror is disposed outside the scanning region on the side opposite to the side where the photodetecting means is disposed, and directs the light beam to the photodetecting element along two optical paths. The photodetecting element and the two mirrors or single half mirror is so disposed that lengths of the two optical paths are equal to respective lengths of two imaginary optical paths to predetermined positions spaced from the scanning surface perpendicularly in opposite directions.

Abstract: A facsimile machine includes a first part for emitting a scanning light beam which is used to record information, a second part for rotating a polygon mirror which reflects the scanning light beam, a third part for receiving information from a source and for detecting a communication system Group III (G3) or Group IV (G4) employed to transmit the information from the source, and a fourth part for controlling a rotational speed of the polygon mirror via the second part depending on the communication system detected by the third part.

Abstract: A method for correcting image exposure and positional errors, arising from the components and geometry of a scanning system, wherein compensating electronic signals are generated to modulate the image data in order to correct said errors.

Abstract: An optical scanning system uses a multiple synchronizing sensing device to device a row of modulated signals into multiple blocks so that the effect of velocity jitter of a polygon scanning mirror is evenly distributed on each zone. In this manner, the influence of printing quality by the velocity jitter is reduced. For instance, the multiple synchronizing sensing device is provided with twenty sensing elements, the influence of the velocity jitter is lessened to be one twenth time as much as its original value. Therefore, the cost is greatly lowered by applying the system of the present invention to a high resolution optical scanning device which utilizes a polygon scanning mirror of less precision.

Abstract: A scan optical apparatus is provided with a first light source for generating a beam for scan optically modulated based on an image signal, a second light source for generating a beam for jitter amount detection, a scanning device for deflecting the beams from the first light source and from the second light source to scan a surface to be scanned, an optical member disposed in the vicinity of the surface to be scanned or at a position substantially optically equivalent to the surface to be scanned, and a detecting device for detecting a beam reflected by the optical member and deflected by the scanning device. The optical member may have reflective portions and nonreflective portions which are repeatedly arranged in a main scan direction, or may be a corner cube array in which a plurality of corner cubes are arranged in the main scan direction. Further, the surface to be scanned may be a recording medium in a recording apparatus.

Abstract: A scanning optical apparatus is used as a recording apparatus having an optical system and a mechanical system and effecting desired recording on a photoconductor by irradiation of a beam. The apparatus comprises marks confirming the beam scanning position on the photoconductor, an error detecting unit for detecting the error of the scanning position from the optimal scanning position, which error is due to an optical factor or a mechanical factor, and a control unit for suitably correcting the scanning position of the beam in real time on the basis of a signal representing the detected error.

Abstract: A sensor for a raster scanner is disclosed which utilizes two elements to detect the position of a scanning light beam relative to a reference level and also detect the start of the scan position. The two elements are placed adjacent to each other in such a manner that on a reference axis, the width of both elements are equal. Each element will have a varying distance between its edges scanned by a spot and such distance on one element will be different than the corresponding distance in the direction of scan on the other element except at the reference axis. Depending on the distances traveled by the light beam on each of the elements, the position of the light beam relative to the reference axis will be detected. The two edges of each element that are adjacent to each other, separating the two elements, must be parallel to each other and orthogonal to the scan direction to also use the crossing of the edges by a light beam as a start of scan detector.

Abstract: An optical system in which arrays of pseudo-corner cube retro reflectors are used to provide optical feedback of the horizontal and vertical positions of a scanning beam. The arrays of reflectors are located above and below the path of the scanning beam near the photoreceptor. The horizontal and vertical position information is then used to correct the alignment of the scanning beam.

Abstract: A laser beam controller comprises a basic pulse signal generating circuit, a delay circuit, a delay control circuit, a pulse generating circuit and a laser beam generator. The basic pulse signal generating circuit generates periodically occurring basic pulse signal. The delay circuit delays the basic pulse signal. The delay control circuit controls the delay time of the basic pulse in the delay circuit according to image data. The pulse generating circuit generates an output pulse having a width corresponding to the delay time of the basic pulse signal. The laser beam generator generates a laser beam for a duration corresponding to the width of the output pulse by said pulse generating circuit. According to the controller, any desired gradation of a pixel of the image is desirably produced.

Abstract: An image scanning and recording method for compensating for a pyramidal error of a mirror surface of a rotating body having at least two reflective mirror surfaces by fine-adjusting an angle of a light beam incident on the rotating body. A scanning lens is put in such a manner that an optical axis of the scanning lens is orthogonal to a rotating axis of the rotating body. An angle made of the incident light beam and a main scanning plate is controlled so that equations (I) and (II) are selectively fulfilled, the main scanning plane being orthogonal to the rotating axis and including the optical axis:tan .alpha.=tan2.delta..multidot.cos(a-b) (I).alpha.=2.delta..multidot.cos(a-b) (II)where a: a rotating angle of a normal line standing on each mirror surface with respect to the optical axis of the scanning lens, b: an angle made of the incident beam and the optical axis of the scanning lens on the main scanning plane, and .delta.: the pyramidal error of each mirror surface with respect to the rotating axis.

Abstract: A novel laser beam scanning system which stores fundamental components in an optical unit by way of including a laser light source, a photosensor for detecting image-writing starting point per scanning, a lens for focusing a laser beam from the laser light source, and a lens for condensing a laser beam reflected by a polygon mirror on the photosensor. The laser beam reflected by the polygon mirror sequentially scans the photosensor, the laser light source, and a recording medium. When the laser beam reflected by the polygon mirror scans the laser light source, the laser light source ceases light-emitting operation. Furthermore, the laser beam reflected by the polygon mirror is condensed on an edge of a photoreceptive surface of the photosensor.

Abstract: A method and apparatus for scanning and exposing in which m laser beams which are arranged in an array so that part of a adjacent laser beams overlap on the photosensitive surface, are main-scanned in a direction intersecting the line along which the laser beams are arranged, while being sub-scanned in the direction in which they are arrayed, to carry out a two-dimensional exposure. The power of at least one of the mth laser beam for the Nth main scanning and the first laser beam for the (N+1)th main scanning is changed, or the distance between the mth laser beam for the Nth main scanning and the first laser beam for the (N+1)th main scanning is changed, to correct density unevenness at the overlapping portion of the mth and the first laser beams.

Abstract: An optical scanning device which can prevent increase of the weight or capacity involved with distortion correction to sufficiently correct the distortion at low cost. A correction arrangement is provided to control the rotating angular velocity of a scanning rotary mirror in accordance with the scanning position of a scanning face. By controlling the rotating angular velocity of the scanning rotary mirror, the distortion aberration on the scanning face is corrected so that sufficiently accurate optical scanning can be performed without optically correcting the distortion aberration.

Abstract: A scanning optical system has a drawing light source, a rotary scanning deflector, a scanning lens and a detection device for detecting a rotational position of the scanning deflector. The drawing light source is controlled by a timing control signal generated by a timing control device as a function of drawing data. The scanning optical system may have a transmission scale, a scanning light receiving portion and a diffusion plate disposed between transmission scale and scanning light receiving portion and adapted to diffuse the monitor beam made incident to the scanning light receiving portion.

Abstract: Beam position sensors detect deviations of a light beam from target positions defined at both sides of a recording drum. Predicted total deviations of light beam from the target positions are calculated as a function of beam position signals detected by the beam position sensors. A piezoelectric element of a sub-deflector is actuated in response to the predicted total deviations. The light beam deflected by a main deflector scans the target positions on a recording medium.

Abstract: An image scanning and recording method and apparatus for compensating for a pyramidal error of a rotating body having at least two reflective mirror surfaces by fine-adjusting an angle of a light beam incident on the rotating body. A scanning lens having a scanning characteristic of f.multidot.sin.theta. is provided on an optical path of the light beam reflected on the rotating body in such a manner that an optical axis of the scanning lens is substantially orthogonal to a rotating axis of the rotating body. The angle of the light beam incident on the rotating body is deflected by a deflecting device within a plane including the rotating axis and the optical axis for each reflective mirror surface based on an equation:sin.alpha.=cos a.multidot.sin 2.delta..multidot.cos(i+.DELTA.)-cos 2.delta..multidot.sin(i+.DELTA.)wherein.alpha.: an angle made of the light beam reflected on the rotating body and a plane including the optical axis and being orthogonal to the rotating axis,.delta.

Abstract: A scanning optical apparatus has a laser beam source for emitting a laser beam, a scanning deflector for deflecting and scanning the laser beam in a principal scanning plane, a scanning lens for imaging the deflected laser beam on a scanning surface to form a spot thereon, an imaging lens for forming the laser beam from the laser beam source into a line spread function image in an auxiliary scanning plane that is perpendicular to the principal scanning plane before the laser beam is made incident to the scanning deflector, a static deflector which is located on the line spread function image and which is adapted to guide the beam from the light source to the scanning deflector and guide the reflected beam from the scanning deflector to the scanning lens, and a holding member for holding at least the laser beam source, the imaging lens and the static deflector separately from other optical elements.

Abstract: A pixel clock phase locked loop for a laser scanner having a rotating multi-faceted polygon receives start-of scan and end-of-scan pulses for each of a plurality of scan lines. A voltage-controlled oscillator outputs a desired frequency of the pixel clock. A desired number of pixels in each scan line is counted, and a pulse is output at the last pixel in the scan line. The end-of-scan pulse and the last pixel pulse are compared, and an output is provided of phase error, the phase error being equal to the difference between the end-of-scan pulse and the last pixel pulse. The phase error for a facet of the polygon is utilized when the facet scans an imaging beam on a next subsequent polygon revolution. The phase error is converted to a voltage, and the phase error voltage is added to a center frequency voltage to generate a composite voltage for controlling the voltage-controlled oscillator.

Abstract: A method of slow, or process, scan direction spot registration or position control in an optical output device, such as a raster output scanner (ROS), may be facilitated by interposing in the image path an electro-optic element whose angular dispersion varies for a given wavelength as a function of the electrical bias applied to it. By orienting the electro-optic element such that dispersion control is perpendicular to the fast or line scan direction of the ROS, varying the electrical bias applied to it varies the dispersion in the slow scan direction. The electro-optic element may be, for example, a prism of AlGaAs. Bias applied to the electro-optic element may be in response to the output of a means for detecting and quantifying such positional errors and/or in response to predetermined correction information output from a processor controlled memory unit or the like. Spot position for single or multiple beam optical output device may be achieved.

Abstract: In an optical output device wherein a beam of light is generated and focused to a spot upon an image plane, such as a photoreceptor in a xerographic printing apparatus, an method for controlling the position of the spot in the slow scan direction of the image plane including the steps of generating a beam of light, deflecting the beam of light by way of an optical beam deflecting elements such that the optical beam deflecting element deflects the path of the beam of light by an amount that is determined by the wavelength of the light beam, and varying the wavelength of the beam of light such that the amount that the beam of light is deflected by the optical beam deflecting element is varied to achieve control of the position of the spot at which the beam of light is incident on the image plane in the slow scan direction.

Abstract: An optical scanning apparatus includes a light-shielding member, disposed between an optical deflection unit and a converging lens, for shielding a scanning beam incident on an edge portion of the converging lens on the scanning starting position side, and the apparatus converts a laser beam into a scanning beam by the optical deflection unit and raster-scans a photosensitve material with the scanning beam through the converging lens to form an image on the photosensitive material. The apparatus may further include a deflection mirror with another light-shielding member, disposed between the converging lens and the photosensitive material, for guiding the scanning beam which does not contribute to image formation immediately after starting of the scanning to a scanning beam detection unit. In the optical scanning apparatus, occurrence of a stray light can be prevented owing to the light-shielding member, whereby an image of high quality free from uneveness of an image or blurring of an image can be formed.

Abstract: A beam deflecting device for scanningly deflecting a beam, comprising a rotational mirror for reflecting the light beam, the rotational mirror having two opposite side surfaces effective to reflect the beam, wherein only the two surfaces are used for scanningly deflecting the beam, and a driver for rotating the rotational mirror in one direction to scanningly deflect the beam. The rotational mirror may have one side surface effective to reflect the beam, wherein only the one surface is used for scanningly deflecting the beam. The rotational mirror has a non-use portion not used for scanningly deflecting the beam, the non-use portion being provided with at least one groove.

Abstract: A scanner system includes a light source for producing a light beam and a scanner for directing the light beam to a spot on a surface to a be scanned and for moving the spot across the surface along a scan line of predetermined length in a series of scan cycles. A reference clock produces a train of M reference pulses during each of the scan cycles such that each of the reference pulses represents the occurrence of a respective one of M segments of the scan cycle. An oscillator produces a train of clock pulses for use in controlling the light beam at a predetermined number of desired pixel positions along the scan line while a frequency control circuit responsive to the reference pulses varies the frequency of the oscillator during the occurrence of each of the M segments of the scan cycle in order to approximate an ideal frequency variation curve the entire scan cycle.

Abstract: A scanning system, having a fixed platen and optical imaging system and a translated reference scale, is provided for scanning of a modulated light beam (or a set of parallel, independently modulated light beams) onto an object surface. The optical system provides a combined light beam including the modulated light beam and a reference light beam. An optical imaging device moves the combined light beam along a scan line, and a translatably mounted beam splitter splits the combined light beam to direct at least some of the reference light beam onto a reference scale and a sensor. The reference scale sensor, which is rigidly attached to the beam splitter, and is responsive to reference beam position in two directions, provides a clocking signal indicative of beam position along the scan line and a vernier position signal indicative of beam position in a direction transverse to the scan line.

Abstract: A scanner system includes a light source for producing a light beam and a director that directs the light beam to a spot on a surface to be scanned moving the spot across the surface along a scan line of predetermined length in a series of scan cycles. The scanner system has a pixel clock for producing a train of clock pulses during each of the scan cycles configured so that some of the clock pulses are spaced apart by a first time interval and others are spaced apart by a longer second time interval in order to maintain timing of the clock pulses according to spot position along the scan line in a manner that compensates for scanner non-linearity in order to reduce pixel position distortion.

Abstract: A diagnostic test process is provided for a visual verification of the spatial illumination characteristics of an illumination system used in a raster input scanner (RIS) system. A calibration reference strip is illuminated by the RIS scanning lamp and the reflected image is detected by a photosensor array. The output data from the photosensor is sampled at predetermined time intervals with each sampling being displayed as a video illumination profile at a display screen. The profile is superimposed on a calibration grid with indicia which allow verification that the lamp calibration is still valid. An out of spec calibration display prompts an operator or tech rep to initiate a recalibration routine or to replace the lamps or possibly clean the optical system components.

Abstract: A scanner system includes a light source for producing a light beam and scanning components for directing the light beam to a spot on a surface to be scanned that is located at a predetermined location relative to the scanning means, moving the spot across the surface along a scan line of predetermined length in a series of scan cycles. The system includes a pixel clock that produces a train of clock pulses during each of the scan cycles using a VCO circuit for producing the train of clock pulses and a control circuit for varying the timing of the clock pulses. The control circuit includes an waveshaping circuit for causing the control signal to have a waveform such that the timing of the clock pulses varies according to the position of the spot along the scan line in order to compensate for scanner non-linearity in a manner reducing pixel position distortion.

Abstract: Output copy quality in a ROS electrophotographic printer is maintained by a method and apparatus designed to selectively vary the beam intensity level of a laser beam scan in response to changed conditions within the scanning or xerographic output subsystems. A test pattern video data input is periodically applied to a laser creating an exposure of the test pattern at the photoreceptor. The resulting print has a plurality of horizontal bands with each band associated with a specific beam intensity correction signal. The test pattern band which appears to provide optimum density is identified. The corresponding digital beam intensity correction signal in the ESS memory is enabled and replaces the previous beam intensity signal controlling the laseer output level.

Abstract: A scanning exposure device comprises a laser light source which emits a laser beam and a polygonal rotating mirror which reflects a laser beam emitted by the laser light source. The scanning exposure device scans the laser beam reflected by the polygonal rotating mirror on a surface of a photoconductive drum for exposure. The scanning exposure device is provided with an intensity correcting unit for correcting the intensity of the laser beam so that the intensity of the laser beam on the surface of the photoconductive drum does not vary regardless of variation of the incident angle of the laser beam falling on the polygonal rotating mirror as the polygonal rotating mirror rotates.

Abstract: A scanning optical device having a light source for illuminating an examination object such as eyground of a humaneye, a scanning illumination system for scanning and illuminating the examination object with the light, and a light receiving system for guiding the light reflected from the examination object to a light-receiving section. The scanning optical device also has a synchronous signal generating optical system capable of directly guiding the light from the scanning illumination system to the light-receiving section without the intermediary of the examination object, and a synchronizing signal extraction device for separating a synchronizing signal exactly synchronous with the image signal from the signal derived from the light-receiving section.

Abstract: A horizontal sync signal generating device for use with an optical printer to determine the starting positions of horizontal scannings on a photoconductive member for forming images thereon. The generation of horizontal sync timing signals is kept constant regardless of any difference in the characteristics of a light beam transmitted via each scanning face of a polygonal rotary member.

Abstract: An apparatus for correcting a scranning beam produced by a polygonal mirror tilting in small surface segments in each mirror surface segment caused by uneven mirror surfaces of the polygonal mirror. Data indicative of the amount of tilting in each of the surface segments is stored in a memory, which is addressed by a data signal indicative of the present scanning position of the polygonal mirror. Output data from the memory is applied to an acousto-optical modulator disposed in the beam path between the light source and the polygonal mirror.

Abstract: A beam position sensor for a beam scanner is disclosed for use in a laser printer. The printer comprises three diode lasers each of which emits at a different wavelength. The beams from the three lasers are combined by the use of dichroic plates to form one combined beam. The combined beam is scanned onto a receiving medium by a polygon. The beam position sensor of the present invention is adapted to sense the position of the polygon in order to provide a synchronizing signal which will insure that each raster line in the printer is started at the proper position. The beam position sensor includes a diode laser and optics for projecting a beam from the laser onto the polygon. The beam is reflected back from the polygon into a photodetector which effects the start of a new raster line at the appropriate time.