Abstract: In an electrophotographic (EP) device, methods and apparatus include determining a delay of one or more sensors (hsync) to accurately know when to start the process of scanning latent images. In one aspect, the sensor includes a leading and trailing edge defined along a direction of laser beam scan travel. Determining the delay includes learning a position of a laser beam on the sensor at a time when a controller connected to the sensor receives a signal from the sensor indicating the sensor is being sufficiently impinged upon by the laser beam. It also includes learning a latest possible position of the laser beam along the direction of laser scan travel where the laser beam can be turned on and still have the sensor assert a signal indicating it has been sufficiently impinged upon by the laser beam. Bi-directionally scanning EP devices are also disclosed, including controllers, photoconductors, sensors, etc.

Abstract: An image forming apparatus including: optical sensor to receive a bias current and to divide the bias current into two output currents, according to positions of a light beam on the optical sensor; and a signal processor to detect horizontal synchronization signals using the output currents, to calculate a positional deviation of the horizontal synchronization signals, and to control a recording time of video data according to the positional deviation.

Abstract: An apparatus for providing delay signals to perform print scan line synchronizations within a laser printer is disclosed. The apparatus includes a voltage-control oscillator, a frequency divider and multiple output control modules. The voltage-control oscillator converts a clock signal to a higher frequency signal. The frequency divider then reduces the frequency of the higher frequency signal. Then, each of the output control modules generates a delay signal, and each of the delay signals is delayed by no more than one tenth of a clock cycle from an adjacent one of the delay signals.

Abstract: Systems and methods are disclosed for determining and generating horizontal synchronization signals for a laser printer having a multi-facet rotating mirror. Each horizontal synchronization signal is determined based on measurements of the facets. The measurements are reflective of the configuration of the mirror and may be acquired using one horizontal synchronization sensor. Respective pseudo horizontal synchronization signals may be generated for multiple emitters based on the measurements obtained with the single horizontal synchronization sensor.

Abstract: An image forming apparatus irradiates a polygon mirror with laser beams from different directions. The polygon mirror reflects the laser beams toward different optical axis directions to scan the laser beams at a predetermined deflection angle. First and second beam detectors are disposed at the beam incident ends in the scanning direction of first and second light scanning sections such that the second beam detector detects the start of the light beam scanning operation at an earlier timing than the first beam detector does. The detection result of the first beam detector is used to set sampling start timing in common between first and second image data. Based on the detection results of the first and second beam detectors, first and second image data are written into a memory, and the first and second laser source sections are controlled based on the image data read out from the memory.

Abstract: A laser light control device for an image forming apparatus designed to improve the auto power control (APC) accuracy and to reduce the control time. A multifunctional optical element has a plurality of different optical characteristics. A detecting unit is adapted to detect laser light from the semiconductor laser. A control unit is adapted to perform control of the write start position of the laser light in the main scanning direction and control of the quantity of the laser light by detecting the laser light by means of the detecting unit after passage of the laser light through the multifunctional optical element.

Abstract: An image forming apparatus includes a light emission source, a polygon mirror, a plurality of image carrying members, an optical detection mechanism, and an instruction mechanism. The light emission source outputs a plurality of optical beams in accordance with image data. The polygon mirror receives the optical beams at different mirror points, and deflects the beams into a first plurality of scanning optical beams in given directions to scan on predetermined scanning lines in a main scanning direction. The plurality of image carrying members rotating in a sub-scanning direction receive the first plurality of scanning optical beams to form primary separate color images. The optical detection mechanism detects a second plurality of scanning optical beams included in the first plurality of scanning optical beams. The instruction mechanism instructs the light emission source to light on and off at timings based on a plurality of detection signals from the optical detection mechanism.

Abstract: A lateral position of a photoreceptor belt is detected by at least a first sensor and a second sensor, respectively located near a first imager and a second imager. The detected lateral positions of the photoreceptor belt by the first sensor is compared to the detected lateral position of the photoreceptor belt by the second sensor. Based on this compared difference, a correction is applied to the position of the second imager relative to the photoreceptor belt. To apply the correction, the location of the start of scan (SOS) of the respective imagers is moved.

Abstract: A timing detection circuit including a first timing detection circuit, a second detection circuit, and an output circuit is disclosed. The first detection circuit detects, among multiphase clocks having n mutually different phases and a frequency of k times the frequency of a reference clock, a closest clock having a clock edge closest to a valid edge of the synchronizing signal and generates first detect signal DET_A indicating the detected clock. The second timing detection circuit detects within which of k successive cycles of the representative clock selected from the multiphase clocks the valid edge of the synchronizing signal is positioned and generates second detect signal DET_B indicating the detected cycle. The output circuit receives the first detect signal and the second detect signal and outputs first output signal OUT_A and second output signal OUT_B.

Abstract: A light-source driving device includes a high-frequency clock generating circuit that generates high-frequency clock signals of which phases are different from each other; an image-data generating circuit that generates a plurality of pieces of image data corresponding to light emitting units in accordance with image information; a write control circuit that generates a plurality of pieces of modulation data corresponding to the light emitting units based on the image data and adjusts output timing of the modulation data individually in units of time corresponding to a phase difference of the high-frequency clock signals; and a light-source driving circuit that drives the light emitting units based on a plurality of pieces of PWM data output from the write control circuit.

Abstract: A disclosed device for generating a pulse-width modulated signal according to image data and based on a pixel clock signal includes a pixel clock generating unit configured to generate the pixel clock signal and a modulated data generating unit configured to generate the pulse-width modulated signal. The pixel clock generating unit includes a multi-phase clock signal generating unit, a comparing unit, a frequency calculation unit, a counting unit, and a pixel clock signal output unit. The modulated data generating unit includes a data converting unit, an edge time calculation unit, and a pulse-width modulated signal output unit.

Abstract: In an image forming apparatus that outputs a reference clock, divides the outputted reference clock based on a set multiple, and generates an image clock based on the division, a width of a synchronization signal that indicates dynamic deviation characteristics is detected, and the multiple is set in accordance with the detected width of the synchronization signal.

Abstract: An image forming apparatus which has a plurality of image forming stations arranged in parallel, each of the image forming stations having a photosensitive drum, and which forms a desired image by combining toner images formed on the photosensitive drums. A laser scanning optical system deflects and scans a plurality of laser beams concurrently with a single polygon mirror to irradiate the photosensitive drums. In a monochromatic mode, the rotation speed of the photosensitive drum for forming a black image is changed higher, and synchronization of writing in a main scanning direction is performed by using one of the laser beams irradiating the other photosensitive drums of which rotation speeds are not changed.

Abstract: A color image forming apparatus of a so-called tandem type which has image forming units in correspondence with colors is provided. In the color image forming apparatus, a color discrepancy amount storage unit stores information of a color discrepancy amount of each of the image forming units, which is measured in advance. A first color discrepancy correcting unit performs color discrepancy correction in a pixel unit by performing coordinate conversion of bitmap data to be printed based on the information of the color discrepancy amount stored in the color discrepancy amount storage unit. A second color discrepancy correcting unit performs color discrepancy correction in less than a pixel unit by performing tone correction of the bitmap data corrected by the first color discrepancy correcting unit based on the information of the color discrepancy amount stored in the color discrepancy amount storage unit.

Abstract: An optical scanning device includes a synchronism detecting element for detecting a light beam scanningly deflected by a deflecting surface of an optical deflector, to determine an image-writing start position of the light beam on a scan surface in a main-scan direction, and a synchronism detecting optical element for directing the light beam scanningly deflected by the optical deflector to the synchronism detecting element, wherein the synchronism detecting optical element is comprised of a prism having a plurality of reflecting surfaces being unified and having a power in a sub-scan direction, and wherein, in a sub-scan section, the prism is configured to place the deflecting surface of the optical deflector and a light-receiving surface of the synchronism detecting element in an optically conjugate relationship with each other.

Abstract: As a scanning light beam which is scanning and traveling away from an effective image region moves passed the location of a sensor, a horizontal synchronizing signal Hsync is obtained as a first detection signal. A deflection mirror surface turns around, thereby reversing the direction in which the scanning light beam scans. This scanning light beam therefore scans an effective image region IR, and a latent image forming operation using this scanning light beam is controlled based on the horizontal synchronizing signal Hsync. Hence, there is a relatively long period of time (T4+T5) since the horizontal synchronizing signal Hsync is obtained until formation of a latent image starts in accordance with the signal Hsync. This secures sufficient time for control of the latent image forming operation based on the horizontal synchronizing signal Hsync, and hence, realizes the latent image forming operation as desired during the time T6.

Abstract: A deflecting unit deflects a light beam emitted by each of a plurality of light-beam emitting units independently to scan surfaces of different bodies to be scanned. Each of a plurality of light-receiving units receives the deflected light beam at a predetermined position in a direction of the deflection. An incident angle of the deflected light beam with respect to a scanning line extending in a direction of scanning on a light-receiving surface of the light-receiving unit is set to be identical for all of the light-receiving units.

Abstract: An image forming apparatus includes a light source that emits a light beam in a main scanning direction according to image data to be used for image formation, a control unit that controls the light source, and detectors that detect the light beam. The main scanning direction is divided into areas and a cycle of a pixel clock is corrected in each area independently based on detection results of the detectors so as to correct an image position and image magnification.

Abstract: Image forming units each form an image of one color, which are superimposed to form a color image, and a pattern used for correcting deviation of the image. A first detector positioned at an image writing starting side, and a second and a third detector each detects the pattern. A first and a second correcting unit having different precisions correct a deviation of an image writing position based on detection by the first, second, and third detectors. A third and a fourth correcting unit having different precisions correct a total-width magnification error based on detections by the first and the third detectors. The fourth correcting unit further corrects a partial magnification error.

Abstract: An image forming apparatus which concurrently exposes by multiple laser beams corresponding to M lines on the photoreceptor, comprising: multiple light sources for emitting laser beams; a memory section for storing the image data; a control section to control the plurality of light sources, wherein the control section is capable of controlling image formation by: a first mode for reading-out of image data for M lines, exposing by multiple light sources of M lines according to the image data for M lines, and forming an image at a predetermined sub-scanning direction image formation speed of VM; and a second mode for reading-out of image data for N lines (where N<M), exposing by multiple light sources of M lines according to read-out image data for N lines and blank data for M?N lines, and forming an image at a sub-scanning direction image formation speed VN, where VN=VM?(N/M).

Abstract: A device and method for controlling timing for starting image formation, and image forming apparatus using such device and method are described. A detector outputs a synchronization detection signal when a light beam enters the detector. The timing for starting image formation is determined based on timing when a counter value, which is counted from timing when the synchronization detection signal is detected, reaches a reference counter value. The reference counter value may be determined according to an operation mode.

Abstract: An image forming apparatus is capable of forming a clear image by using laser beams projected from a plurality of laser light sources. The image forming apparatus forms an electrostatic latent image on a medium to be scanned by laser beams, which are projected from a plurality of laser light sources and periodically deflected by a rotational deflecting unit, so that the laser beams scan the medium, which is uniformly charged and moving in a sub-scanning direction, in a main-scanning direction perpendicular to the sub-scanning direction. A pixel clock generating unit generates pixel clocks, which are used for controlling timings of projection of the laser beams, separately for each of the laser light sources, and for performing a phase change of each of the pixel clocks; and a phase control unit that controls independently each of the pixel clocks.

Abstract: The positioning of image data written along a laser beam scan path in the scan direction, e.g., the margin and/or line length is adjusted in a manner that compensates for changes in the laser beam scan path as a result of one or more operating conditions, such as changes in temperature. Further, the positioning of image data in the process direction may be adjusted in a manner that compensates for changes in the laser beam scan path as a result of the one or more operating conditions.

Abstract: A light-emission control unit controls an emission of a light beam from a light-beam generating unit based on an input image signal. A light-beam scanning unit deflects the light beam in a main scanning direction and irradiates the deflected light beam on an image carrier. An anomalous-light emission detecting unit detects an anomalous light emission of the light-beam generating unit when there is no image signal input to the light-emission control unit. A control unit performs an error processing based on the detected anomalous light emission.

Abstract: An electronic device includes a motor, a detector, and a controller. The detector detects a rotational speed of the motor. The controller selects a gain from a plurality of gains based on the rotational speed and controls rotation of the motor through feedback control. The controller uses a first gain from startup of the motor until the motor initially reaches a predetermined rotational speed after the startup. The controller switches to a second gain smaller than the first gain when the motor initially reaches the predetermined rotational speed after the startup, and uses the second gain in a predetermined range with respect to the rotational speed. The predetermined range is defined between a lower limit smaller than the predetermined rotational speed and a higher limit larger than the predetermined rotational speed.

Abstract: A disclosed optical scanning apparatus for scanning a scanning surface using a light beam, the optical scanning apparatus comprises: a light source having a plurality of luminous sources; a deflection unit collectively deflecting a plurality of light beams emitted from the plural luminous sources; a light guiding unit guiding at least a portion of each of the plural light beams to a predetermined direction without using the deflection unit; and a photo-detection system receiving the plural guided light beams and the plural deflected light beams and outputting a signal based on the received light beams.

Abstract: A scanning time is divided by the number of sides of a polygon mirror to obtain a value N. Then, it is determined whether an error has occurred. When no error has occurred, the value N is stored in an NVRAM, and a magnification correction value is calculated. Values M and N of a PLL are set based on the correction value. A difference between a clock set by the PLL and an ideal pixel clock frequency is corrected to an optimal magnification by changing a phase. The ideal pixel clock frequency after magnification correction is calculated from V=N0/N×F. The values M and N of the PLL that provide a frequency closest to the ideal frequency V are acquired. A difference between a frequency V? acquired from the values M and N and the ideal pixel clock frequency V is corrected by the clock phase.

Abstract: A color image forming apparatus in which an engine controller outputs an operation start signal to write controllers at a timing at which a registration sensor detects a position of a sheet of transfer paper. Synchronization detection signals for colors are used to set reference positions for front edges of the colors in a main scanning direction. A write controller for a reference color outputs a write-operation start signal so as not to cut the synchronization detection signals each indicating one line for one color in the main scanning direction and line synchronization signals, into two parts in their longitudinal direction. The write-operation start signal is used to set a reference time point when the write controllers make transfer requests for image signals for the colors to an image processor.

Abstract: The image forming apparatus comprises: a first photosensitive drum; a second photosensitive drum; deflective scanning means for deflecting a laser beam and scanning by rotation; first laser irradiation means including a plurality of light emitting sources of laser beam for irradiating the first photosensitive drum, to irradiate the deflective scanning means with the laser; second laser irradiation means including a plurality of light emitting sources of laser for irradiating the second photosensitive drum, to irradiate the deflective scanning means with the laser beams; supporting means for supporting the first laser irradiation means and the second laser irradiation means; and a rotation supporting member for rotationally moving the first laser irradiation means, the second laser irradiation means and the supporting means integrally with respect to an axis generally parallel to the emanating axis of the laser beam to be emitted from the first laser irradiation means.

Abstract: An image forming apparatus capable of properly performing an initialization of a control circuit including a laser diode driver circuit, includes a light source, a photoreceptor, a deflector, and a controller. The photoreceptor is built in the light source to detect incident light. The deflector deflects the laser light into a scanning laser beam. The controller controls the light source to light on and off, and obtains a laser light emission amount of the light source relative to a current flowing through the light source based on a detection of incident light by the photoreceptor. The controller determines the laser light emission amount of the light source during a time period when a path of the laser light from the light source is headed to a reflection surface of the deflector at an incident angle of approximately ninety degrees.

Abstract: An image forming apparatus includes an intermediate transfer member, a sensor, and two image forming units. Each of the image forming units includes an image carrier, an image writer, two development rollers, and a switcher. The image writer writes an electrostatic latent image on the image carrier. Each of the development rollers selectively driven by the switcher visualizes the electrostatic latent image to form toner images in four colors. The toner images are transferred and superimposed onto the intermediate transfer member to form a color toner image. The color toner image is transferred onto a transfer sheet. One or more marks are formed on the intermediate transfer member. The sensor detects one of the marks. The image writer starts writing in synchronism with a sync clock signal of the image writer output immediately after the sensor detects the mark or output after a predetermined time period elapses after the sensor detects the mark.

Abstract: A method of diagnosing a state of a horizontal synchronizing signal is provided for an optical scanner, which includes a rotary polygon mirror having a rotation sensor, a control clock competing with a signal of the rotation sensor to control the rotary polygon mirror to a constant speed, a laser beam illuminating the rotary polygon mirror to be used in a scanning operation, and a scanning beam detector detecting the laser scanning beam at a prescribed position and outputting a horizontal synchronizing signal to trigger a control of the scanner. The method includes using the optical scanner, and presetting an effective period of outputting the horizontal synchronizing signal by counting the control clock for the rotary polygon mirror, the counting being triggered by a previous horizontal synchronizing signal.

Abstract: There is described an apparatus, which includes an image-forming section to form a multicolor image on a recording medium by recording the unicolor images in such a manner that the unicolor images overlap each other, based on printing image data sets of them, and a controlling section that determines at least a sub-scanning velocity in a sub-scanning direction relative to the recording medium, corresponding to a printing magnification factor, so as to adjust an output-start timing in the sub-scanning direction for every printing image data set, in response to the sub-scanning velocity determined in advance. Further, the controlling section also determines a main-scanning velocity in a main-scanning direction, corresponding to the printing magnification factor, so as to adjust output-start timings in both the main-scanning direction and the sub-scanning direction for every printing image data set, in response to the main-scanning velocity and the sub-scanning velocity, both determined in advance.

Abstract: A magnification correction controller corrects magnification in a main scanning direction by changing a timing of an image signal based on a time difference between a first detection time in a predetermined position along a main scanning line of the image carrier to which the laser beam is irradiated and a second detection time in a position different from the predetermined position along the main scanning line. The magnification correction controller corrects the magnification in the main scanning direction by changing a timing of the image signal corresponding to a color different from a predetermined color, based on the time difference measured for the predetermined color.

Abstract: A frequency modulation apparatus capable of reducing a peak level of a radiation noise of a characteristic frequency band due to an image clock. This frequency modulation apparatus is used in an image formation apparatus having an image bearing body to be scanned by a laser beam. An auxiliary clock calculating portion calculates an auxiliary clock period based on a reference clock period and a modulation coefficient, and an image clock generating portion generates the image clock in which a frequency is different at least in one portion and other portions of an image area on a main scan line to be scanned by the laser beam on the image bearing body based on the initial period value set in advance and the auxiliary clock period, and the image clock generating portion performs a frequency modulation so that the frequency of the image clock changes within a predetermined fluctuation.

Abstract: An optical scanning device that includes: a light-emitting unit that emits laser light to a polygon mirror on the basis of a turning-on signal; a sensor unit that detects laser light reflected by the polygon mirror and outputs a sensor signal; and a noise removing unit that outputs a laser light detection signal when the sensor signal is output during an output period of the turning-on signal.

Abstract: The present invention discloses a clock signal generation circuit for generating one or more clock signals for performing a scanning operation by scanning a light beam from a light source to a scan target. The clock signal generation circuit includes a determination circuit for determining authenticity of start information in accordance with at least one of the length of the start information and the timing at which the start information is input, and a generation circuit for generating the clock signals in synchronization with the start information when the determination circuit determines that the start information is authentic.

Abstract: An image forming apparatus which has a plurality of image forming stations arranged in parallel, each of the image forming stations having a photosensitive drum, and which forms a desired image by combining toner images formed on the photosensitive drums. A laser scanning optical system deflects and scans a plurality of laser beams concurrently with a single polygon mirror to irradiate the photosensitive drums. In a monochromatic mode, the rotation speed of the photosensitive drum for forming a black image is changed higher, and synchronization of writing in a main scanning direction is performed by using one of the laser beams irradiating the other photosensitive drums of which rotation speeds are not changed.

Abstract: An optical scanning device includes a light source device having light emitting members of a number N (N is an integer not less than 2) disposed with a tilt with respect to a sub-scan direction and a main-scan direction, a deflecting device for scanningly deflecting light beams of the number N from the light emitting members, an input optical system for directing the light beams from the light source means to the deflecting device, an imaging optical system for directing the deflected light beams to a surface to be scanned, a synchronism signal detecting device for detecting a portion of a light beam scanningly deflected by the deflecting surface and producing writing start timing signals for the light beams upon the surface to be scanned, and a synchronism detecting optical system for directing the deflected light beams to the synchronism signal detecting device, wherein the synchronism signal detecting device detects a light beam emitted from a light emitting member among the light emitting members of the n

Abstract: A multi-beam image forming apparatus includes: first and second semiconductor laser arrays each having n laser elements; a multi-beam generation unit that generates 2n laser beams by synthesizing laser beams generated by the first and second semiconductor laser arrays; a beam detection unit that generates synchronous detection signals to obtain synchronous scanning of the respective laser beams; and a control unit. The beam detection unit includes first and second beam detection units disposed substantially at a same position in a main scanning direction and adjacently disposed in a sub-scanning direction. The n laser beams of the first and second semiconductor laser arrays are detected by the first and second beam detection unit, respectively. The control unit controls image formation start positions of the 2n laser beams on the basis of the synchronous detection signals output from the first and the second beam detection units.

Abstract: A scanning system is adapted to scan an image beam across a photoconductive surface. The scanning system includes an oscillating mirror and is operable to generate an image beam and to reflect the image beam off the oscillating mirror to bidirectionally scan the image beam across the photoconductive surface and thereby discharge regions on the surface. The system is further operable to dynamically scale an intensity of the image beam as a function of a position of the image beam on the photoconductive surface.

Abstract: An image formation apparatus comprises an optical flat including: a cabinet; and a scanning optical system containing a light deflection section, the scanning optical system being housed inside the cabinet, so as to emit light scanned by the light deflection section and form an image by the scanned light, wherein the image formation apparatus further comprises a heating section being placed on an outer side of the cabinet to heat the optical flat.

Abstract: A measuring unit measures a time difference between detections of the optical beams by an optical beam detector arranged on either side of an image carrier with respect to a horizontal scanning direction. A magnification correcting unit determines whether a beam spot position adjustment amount corresponding to each of a plurality of developing colors preset by the sub position correcting unit exceeds a threshold preset for each of the plurality of developing colors, and depending on the result of the determination, performs magnification correction of the image by changing a beam spot position interval on a scanning line in units of a line or lines, or by changing a beam spot position interval on a scanning line in units of pixel.

Abstract: A beam light scanning device includes an image data processing unit operable to output image-processed data of neighboring pixels in such a way that the data is divided for distribution into first pixel data and second pixel data. The scanner also includes a synchronizer circuit that receives the first and second pixel data as output from the image data processor and outputs these pixel data while letting them be synchronized with clocks as synchronized based on a horizontal synchronous signal. The scanner further includes a couple of pulse width modulators or “PWMs”, a synthetic circuit, and a laser diode module. The PWMs are for adjustment of the pulse widths of the first and second pixel data as output from the synchronizer circuit respectively. The synthetic circuit combines together the pulse width-adjusted first and second pixel data. The LD emits a light beam indicative of the resultant combined pixel data.

Abstract: Skew compensation apparatus for compensating for skew of a multi-beam scanning source, comprises: delay commencement detector(s) for detecting the start of a beam scanner position, position detectors for detecting the position of the multiple beams at a predefined interval following the commencement, so that the position indicates skew of the respective beam, and compensating electronics for automatically inserting a compensation for the skew by altering a delay into a timing signal for switching the respective beam. The commencement detector can be an existing start of scan detector and the apparatus can be built into the writing head, particularly at the conjugate location to the focal plane or at the focal plane of a laser printer or the like to provide a self-calibrating printer.

Abstract: An image forming apparatus according to the present invention irradiates a polygon mirror with laser beams from different directions, allows the polygon mirror to reflect the laser beams toward different optical axis directions to perform main scanning operation for the laser beams at a predetermined deflection angle. First and second beam detectors are disposed at the beam incident ends in the scanning direction of first and second light scanning sections to detect the start of light beam scanning operation such that the second beam detector detects it at an earlier timing than the first beam detector does. The detection result of the first beam detector is used to set sampling start timing in common between first and second image data. Based on the detection results of the first and second beam detectors, first and second image data are written into a memory, and the first and second laser source sections are controlled based on the image data read out from the memory.

Abstract: A multi-beam scanner includes light sources, a deflector deflecting the beams emitted from the light sources at an equiangular velocity, a scanning image-forming optical system guiding the deflected beams to a surface so as to be formed into light spots on the scanned surface, a light receiving device receiving the beams deflected toward optical write-in starting portions on the scanned surface as synchronizing beams, and a synchronizing beam optical system guiding the beams deflected toward the optical write-in starting portions on the scanned surface to the light receiving device. The scanning image-forming optical system includes two or more scanning positive lenses, with a region having a positive power in a main scanning direction on an optical write-in starting side, and each deflected beam received by the light receiving device passes through one or more but not all of the scanning positive lenses to be guided to the light receiving device.

Abstract: An image recording method of recording an image onto an image recording surface by dot patterns by scanning a recording head having recording element units arranged in a direction intersecting a scanning direction, the recording element units having a light source and an optical system which receives light from the light source, forms light beams which are arranged two-dimensionally, and focuses the light beams on the image recording surface. The method includes: measuring displacement amounts of positions of light beam spots on the image recording surface generated due to a change in optical magnification of the optical system; changing a light-emitting timing at a time of start of scanning in the scanning direction, on the basis of a displacement amount in the scanning direction; and changing a resolution in the direction intersecting the scanning direction, on the basis of a displacement amount in the direction intersecting the scanning direction.

Abstract: A frequency modulation apparatus capable of reducing a peak level of a radiation noise of a characteristic frequency band due to an image clock. This frequency modulation apparatus is used in an image formation apparatus having an image bearing body to be scanned by a laser beam. An auxiliary clock calculating portion calculates an auxiliary clock period based on a reference clock period and a modulation coefficient, and an image clock generating portion generates the image clock in which a frequency is different at least in one portion and other portions of an image area on a main scan line to be scanned by the laser beam on the image bearing body based on the initial period value set in advance and the auxiliary clock period, and the image clock generating portion performs a frequency modulation so that the frequency of the image clock changes within a predetermined fluctuation.

Abstract: A scanning optical apparatus includes a light source capable of being modulated, a deflecting element for deflecting and scanning a beam emitted from the light source, a scanning optical element for imaging the deflected beam into a spot shape on a scanned surface, and an optical element for synchronous detection for directing the deflected beam from the deflecting element to a sensor to take the timing of image writing beginning. The scanning optical apparatus further inclueds a scanning position detecting device for making the optical axis of the optical element for synchronous detection and the principal ray of the beam from the deflecting element for taking the timing of image writing beginning coincident with each other, and detecting the position of the beam at a point having at least one image height separate from the optical axis of the scanning optical element.