Abstract: A printer prints a black mark BM having a left mark edge BMa and a right mark edge BMb on a paper P. An encoder offset SH_L_EDG for the left mark edge BMa is set based on the difference between the carriage position (encoder value PR_ENC_L) that is detected when the print head 10 prints the left mark edge BMa and the carriage position (encoder value SEN_ENC_L) that is detected when the media sensor 68 detects the left mark edge BMa. Similarly, an encoder offset SH_R_EDG for the right mark edge BMb is set based on the difference between the carriage position (encoder value PR_ENC_R) that is detected when the print head 10 prints the right mark edge BMb and the carriage position (encoder value SEN_ENC_R) that is detected when the media sensor 68 detects the right mark edge BMb. In this way, the printer can suppress the effects of mounting error and can prevent a decline in accuracy when detecting edges of the paper P.

Abstract: There is provided an image forming apparatus able to form color images of higher quality without color deviation in an inexpensive way. A displacement driving unit is provided to move an optical element unit to displace a beam spot on a photoconductor in the sub scanning direction. A first detection unit is provided to detect the turning cycle of a transfer member, and a second detection unit is provided to detect writing timing of a laser beam from the optical element unit on the photoconductor. When writing a number of toner images on the photoconductor in sequence, the optical element unit is moved and the beam spot is displaced on the photoconductor in the sub scanning direction to correct the writing position on the photoconductor and eliminate deviation of image transfer positions on the transfer member.

Abstract: A method and apparatus for aligning in five degrees of freedom a multichannel laser printhead to be used in thermal transfer of material from a donor to a substrate is disclosed.

Abstract: The present invention relates to a method for controlling exposure and a scan-exposure apparatus, which are used when a photosensitive material is scan-exposed. In the present invention, distance between a light source and a recording medium can be controlled on the basis of pre-measured distance correction data and timing at which light is emitted from the light source can be controlled on the basis of pre-measured light-emission correction data. Accordingly, it becomes possible to prevent the light beam irradiates the recording medium from going out of focus and to reduce the amount by which the position irradiated with the light beam deviates from a preset standard position.

Abstract: An image forming apparatus forms on a photoconductive body an evaluation chart including first patterns and second patterns. In the first pattern, with respect to a row of dots formed in a main scan direction by a predetermined light beam, a row of dots formed by a next light beam is shifted in the main scan direction, and in the second pattern, with respect to the row of dots formed in the main scan direction by the predetermined light beam, the row of dots formed by the next light beam is shifted in the main scan direction but in a direction opposite to a shift direction of the first pattern. The evaluation chart includes a first pattern group which is formed by the first patterns which are repeated, and a second pattern group which is formed by the second patterns which are repeated.

Abstract: An input value Y of digital data with respect to a D/A conversion unit for coarse adjustment and an input value X of digital data with respect to a D/A conversion unit for fine adjustment are controlled so as to allow a galvano-mirror to rotate in a direction in which a setting position of a laser beam B is within a predetermined position.

Abstract: An image forming apparatus including a light beam generating and modulating device that generates and modulates a light beam based on an image signal, and a light beam deflecting device that deflects the modulated light beam and scans an image carrier to form an image. A pair of light beam detecting devices detects the deflected light beam at two separate positions on a main scanning line. A time difference measuring device measures a time difference between time periods when the light beam is detected by one of the light beam detecting devices and by the other of the light beam detecting devices. An image magnification correcting device changes write clock frequency of the light beam and rotation number of the light deflecting device based on the time difference to correct magnification error in the main scanning direction of the image on the image carrier.

Abstract: A light beam position detecting device detects the passage positions of a plurality of light beams for scanning the surface of a photosensitive drum. The light beam position detecting device has a sensor pattern for generating an output which is continuously changed in a wide range with a variation in the passage position of the light beam in a sub-scanning direction perpendicular to a main scanning direction of the light beam. The sensor pattern precisely detects the relative scanning position of the light beam in a wide range. The passage positions of the plurality of light beams for scanning the surface of the photosensitive drum are controlled to a preset position based on the output of the sensor pattern.

Abstract: The sensors SP and SO detect a position in the sub-scanning direction through which a light beam scanned by the scanning unit passes. The correction pulse generator corrects the amplitude of the position signal obtained by the sensors SP and SO. The integrator integrates the position signal corrected by the correction pulse generator, and outputs the integration value corresponding to the sub-scanning direction position. The CPU 51 adjusts the correction amount of the correcting unit (the amplitude of the pulse) such that the integration value output from the integrator falls within a target range. The target range is varied in accordance with the light beam position that changes due to an influence caused by a change in the surrounding temperature or the like.

Abstract: In a pattern writing apparatus for writing a plurality of pattern blocks of LSI chips which are arrayed on a substrate, provided are a rasterization part (312) for rasterizing LSI data 931, an expansion/contraction rate calculation part 313 for obtaining the expansion/contraction rate of a substrate (9) on the basis of an image from a camera (15a), a data correction part (314) for correcting raster data (932) in accordance with the expansion/contraction rate and a data generation part (315) for generating writing data on the basis of the corrected data. From the writing data generated by the data generation part (315), an array of pattern blocks in which the width of a non-pattern region between adjacent ones of the pattern blocks is changed while the width of each pattern block is maintained is written on the substrate.

Abstract: The relationship between first and second side images is evaluated to determine how the position of the paper and/or the size and arrangement of an image can be manipulated to compensate for paper shrinkage caused by fusing. Show through is reduced by performing setup to adjust a pixel clock frequency and/or a photoreceptor speed, determining a residual magnification error, determining margin shifts to compensate for the residual magnification error, and applying the margin shifts. Paper shrink effects on registration can be compensated for using determinations made during a typical printer setup. Show through errors can be reduced without using a paper conditioner to pre-shrink or re-wet the paper. In simplex and duplex printing, the show through errors worsen as the image moves away from the registration edge. Using information obtained during setup, a margin shift is determined that results in a significant reduction in the maximum show through for each image.

Abstract: A printing apparatus with a plate-making mechanism comprises a data modification part for modifying width of an original image in a subscan direction by computation to obtain a modified image and a controller for recording an image with its length in a main scan direction modified by shifting a writing clock in image recording. This allows reduction in the amounts of computation as compared with a case where modification against extension of a paper in the main scan direction and subscan direction is performed only by computation and makes it easy to control modification as compared with a case where the modification in the main scan direction and subscan direction is performed only by shifting the writing clock and a moving clock for a writing head. Thus, it becomes possible to easily correct the influence of extension of paper in printing.

Abstract: Described is a method for imaging a printing form (10) using one or more laser diode bars having a number n of individually controllable laser diodes (16) whose imaging spots (20) lie essentially in a row on the printing form (10), for the case that at least one laser diode (16) on the laser diode bar (14) cannot be activated, but a maximum number m of laser diodes (16) whose neighboring imaging spots (20) have a distance a on the printing form (10) are able to be activated. The relative speed between the imaging device (12) and the printing form (10) is increased by the factor (n/m). The exposure time per printing dot (69) is shortened by the factor (m/n). In order to input in each case an amount of energy per printing dot (69) on the printing form (10), imaging is carried out using the m activatable laser diodes (16) with an imaging intensity which is a function of the exposure time and of the specific amount of energy per printing dot (69).

Abstract: An image forming apparatus has a CIS disposed in an area where a sheet passes in such a fashion that read pixels of the CIS are arranged in a direction perpendicular to the feeding direction of the sheet. A part of the read pixels (e.g., 1000 pixels) that corresponds to {fraction (1/7)} of all the read pixels are repeatedly read with a short period (TS) to detect the position of the leading edge of the sheet being fed. After waiting a predetermined period of time after the timing of detection of the leading edge position of the sheet, a laser beam is irradiated onto a photosensitive drum to start writing an image in the subscanning direction. Further, read pixels (e.g., 6000 pixels) that corresponds to {fraction (6/7)} of all the read pixels are repeatedly read with a long period (TL) to detect the position of the side edge of the fed sheet.

Abstract: A laser beam position sensing arrangement using two similar sensors where, instead of the first sensor being aligned normal to the beam scan path, the angle which bisects the two sensors is aligned normal to the beam scan path. The average of times T1 and T2 at which the laser beam is incident the respective sensors is used for the horizontal or start of scan value, and the difference (T2−T1) is proportional to the vertical or process direction value. From the difference between the two determined times, the longitudinal beam position may be determined.

Abstract: In an implementation of disc media marking, a laser renders an image on a disc media as laser marks written in concentric circular tracks. A print control application determines a radius of a first circular track such that a circumferential length of the first circular track corresponds to an integral number of laser mark spaces. The print control application further determines a radial increment from the first circular track to a second circular track such that a circumferential length of the second circular track corresponds to a second integral number of the laser mark spaces.

Abstract: An image recording device equipped with a focal point adjusting mechanism is provided. Displacement of the focal point of a light beam emitted from a recording head in correspondence with the traveling amount of the recording head in the axial direction of a drum is measured in advance after the image recording device has been assembled. Correction data for compensation of the displacement is prepared from the measured amount of displacement and stored in a correction table. At the time of image recording, the focal length is corrected by reading out the correction data from the correction table in response to the traveling amount of the recording head and moving a moving stage in the direction of the optical axis. Therefore, slight displacement of the focal point, which may compromise image quality, can be compensated with a simple device.

Abstract: An edge detection apparatus for detecting an edge on a surface. The apparatus comprises a source of coherent radiation for generating a radiation beam and directing the beam onto the surface. A radiation detector is located so as to detect radiation diffusely reflected, but not specularly reflected, from the surface. A system is provided for causing relative scanning movement between the radiation beam and the surface. A monitor is coupled to the detector for monitoring the intensity of the detected radiation.

Abstract: A method and a device for imaging a printing form (48) via at least two imaging modules (40,418) which each have at least one light source are disclosed for avoiding the banding effect that an imaging in a transition region (416). The two imaging modules (40,418) are provided in such a manner that a number of at least partially not-simply connected printing dots are produced in the transition region (416) by the first imaging module (40) and the complementary, not-simply connected printing dots are produced in the transition region (416) by the second imaging module (418).

Abstract: Correction of a positional deviation of split scanning lines in a sub scanning direction and modification of an image information split position are performed with a simple circuit configuration. When addresses of storage units in which split image information pieces A and B are stored are determined by address specification units, a overlap area is allocated in advance so that a split position is set based on image information split position information. As a result, dummy signals corresponding to off signals for a light source are stored in a storage unit other than storage units in which image information is stored. The dummy signals exert no influence on counterparts in the overlap area, and it is unnecessary to change a write address each time a split position is modified.

Abstract: An apparatus for forming an image by use of a plurality of light beams, which are simultaneously modulated according to image signals and joined together on a photoconductive surface to form the image. The apparatus includes a photoconductive drum having the photoconductive surface and a reference mark, a pattern supplying unit which supplies image data in synchronization with detection of the reference mark associated with rotation of the photoconductive drum, and drawing systems which create moir{acute over (e )} stripes on the photoconductive surface by simultaneously drawing overlapping sets of slanted lines with the respective light beams according to the image data, and draw a reference position mark on the photoconductive surface according to the image data.

Abstract: A pixel clock generation apparatus includes a detector detecting a time interval between two horizontal synchronization signals. A comparing part compares the time interval detected by the detector and a target value, and outputs the difference. A phase shift data generation part stores one or more lookup tables each storing a pattern of phase shift data for controlling a phase shift amount of a pixel clock, and reads and outputs the phase shift data from the lookup table based on the difference that is output from the comparing part. A high frequency clock generation part generates a high frequency clock. A pixel clock generation part generates the pixel clock whose phase is controlled in accordance with the phase shift data based on the high frequency clock.

Abstract: Multiple light beams are reflected by a resonant oscillator through an optical system onto light sensitive drums of a printing system. Information is encoded onto the beams, and an image is printed based on the encoded information. Preferably four beams and four drums are used to print four colors. The oscillator includes an oscillating plate mounted on the torsion springs for resonant oscillation. A magnet is mounted on the oscillating plate and an oscillating magnetic field oscillates the magnet and the plate. Sensors detect the position of at least one of light beam to synchronize the operation and speed of the encoder, drums and oscillator. The oscillator may include multiple reflective surfaces on one or more sides of an oscillating plate, and one or more beams may be reflected from each surface.

Abstract: The transfer apparatus transfers an image displayed in an image display area of an image display unit of transmission type to an image forming area of a light-sensitive recording medium by means of light passing through the image display unit. The apparatus has an image processing section by means of which either a size or a display position of the image to be displayed in the image display area or both are adjusted prior to image display in accordance with either a size of the image forming area or a relative position of the image forming area with respect to the image display area or both.

Abstract: A method for repositioning a mark on a belt after an image on paper registration process, which includes printing a test pattern, measuring at least one test pattern parameter, detecting a mark on a belt and detecting at least one imaging error associated therewith, using the at least one test pattern parameter and the at least one imaging error to determine the lateral distance required to shift a particular image to a desired location on the belt and shifting the image to the desired location.

Abstract: The timing sensors provided in the light-receiving part of a beam-detecting unit have different lengths in the sub-scanning direction. The beam-passing position sensors provided in the light-receiving part of the beam-detecting unit are longer than the timing sensors, in the sub-scanning direction. The intensity of a light beam is controlled in a reference-pitch measuring routine.

Abstract: A system architecture for scanned non-linearity correction in a printer uses any raster output scanner having scanned non-linearity profile previously stored in memory from a test station installed with any pixel board. The pixel board includes a correction table register wherein the pixel board utilizes the scanned non-linearity profile of the raster output scanner to calculate the correction table register to correct for pixel misregistration.

Abstract: A method of sensing the pitch or relative location of a lenticular lens on a sheet of transparent lenticular material of the type having a repeating pattern of cylindrical lenses on one side and a flat opposite side, comprising the steps of: forming a beam of light; focusing the beam of light into a spot smaller than the pitch of the cylindrical lenses onto the lenticular material; moving the lenticular material relative to the beam in a direction perpendicular to the axes of the cylindrical lenses to modulate the angle of reflection or refraction of the beam of light; and sensing the position of the modulated beam of light to determine the pitch or relative location of lenticular material to the focused spot.

Abstract: A method of sensing the pitch or relative location of a lenticular lens on a sheet of transparent lenticular material of the type having a repeating pattern of cylindrical lenses on one side and a flat opposite side, comprising the steps of: forming a beam of light; focusing the beam of light into a spot smaller than the pitch of the cylindrical lenses onto the lenticular material; moving the lenticular material relative to the beam in a direction perpendicular to the axes of the cylindrical lenses to modulate the angle of reflection or refraction of the beam of light; and sensing the position of the modulated beam of light to determine the pitch or relative location of lenticular material to the focused spot.

Abstract: An image forming apparatus for forming an image by modulating laser light in correspondence with an image signal. A pulsewidth modulation signal is generated in correspondence with input image data. A laser drive control circuit has a photosensor PD which detects laser light emitted from a laser diode LD and generates a detection current, a resistor which generates a detection voltage corresponding to the detection current outputted from the photosensor PD, a buffer in which the generated detection voltage is inputted, an amplifier which amplifies an output from the buffer, and a constant current source and a switch to add a predetermined current to the detection current for compensation for reduction of output voltage due to offset voltages of the buffer and the amplifier. Control data for controlling maximum and minimum pulsewidths in the pulsewidth modulation signal are obtained based on the detection voltage, and generation of the pulsewidth modulation signal is controlled.

Abstract: An electronic still camera with a printer includes a vibration detector and a system controller. The vibration detector detects vibration relative to a moving direction of an exposure head of the printer. When the vibration detector detects the vibration exceeding a prescribed level, the system controller interrupts a printing operation of the printer. After that, when the vibration detector detects the vibration falling below the prescribed level, the system controller resumes the printing operation. The exposure head is adapted to be moved, performing the printing operation one line by one line. Until the printing operation for one line is completed, the system controller suspends to interrupt the printing operation.

Abstract: In this invention, the relationship between the attachment position of a sensor and the formation positional shift of a color image is checked by moving a color misregistration detection sensor along an attachment position candidate line that is defined in advance in a direction perpendicular to the rotational direction of an endless-belt-shaped transfer body. A specific attachment position on the sensor attachment position candidate line, at which color misregistration of the color image at a side edge portion of the transfer body becomes equal to the maximum value of color misregistration at a portion except the side edge portion, is found. The sensor is fixed at a position that satisfies the specific attachment position and opposes the color image formation surface of the transfer body. Accordingly, the image forming apparatus is controlled to correct color overlay on the basis of the detection signal of the color image by the sensor.

Abstract: The image recording method and apparatus deflect light from a group of two-dimensionally disposed light source elements to move an image formed on a recording medium in accordance with a movement of the recording medium, or shift modulation data of the group of two-dimensionally disposed light source elements in a first moving direction of the recording medium on the group of two-dimensionally disposed light source elements in synchronism with the movement of the recording medium, and thereby have the image remain stationary relatively to the recording medium in the main scanning direction, as well as shift sequentially modulation data of the group of two-dimensionally disposed light source elements in a direction opposite to a second moving direction of the optical system in synchronism with a movement of the optical system in the auxiliary scanning direction, and thereby having the image also remain stationary relatively to the recording medium in the auxiliary scanning direction.

Abstract: A laser beam sensor assembly in an electrophotographic machine includes a sensor device detecting a position of a laser beam in a process direction. The sensor device has a detection range in the process direction. The sensor device has at least one slot or at least one projection. A fixed structure has an other of the at least one slot and the at least one projection. The at least one slot and the at least one projection coact to allow the sensor device to slide in the process direction to a location such that the laser beam is at a desired position within the detection range of the sensor device.

Abstract: An apparatus for lettering or marking articles by means of a laser beam, comprising a laser to produce a laser beam and a focussing optical system to produce a larger radiation density on the surface of the article wherein a lens system is provided the focussing plane of which constitutes an area which is curved away from the lens system.

Abstract: Two-dimensional image data is divided into two-dimensional image data of numbers of main scanning lines depending on intervals between laser beams. While effective signals are high in level, the divided two-dimensional image data simultaneously start being outputted as effective image data. While effective signals are low in level, the two-dimensional image data are made ineffective. In this manner, recording ranges covered by the laser beams are adjusted to record a two-dimensional image. A high-quality two-dimensional image can thus be recorded at a high speed in a desired recording position on a photosensitive medium by exposure to light beams with an inexpensive arrangement without the need for a highly accurate adjusting process and a highly accurate adjusting mechanism.

Abstract: The relationship between first and second side images is evaluated to determine how the position of the paper and/or the size and arrangement of an image can be manipulated to compensate for paper shrinkage caused by fusing. Show through is reduced by performing setup to adjust a pixel clock frequency and/or a photoreceptor speed, determining a residual magnification error, determining margin shifts to compensate for the residual magnification error, and applying the margin shifts. Paper shrink effects on registration can be compensated for using determinations made during a typical printer setup. Show through errors can be reduced without using a paper conditioner to pre-shrink or re-wet the paper. In simplex and duplex printing, the show through errors worsen as the image moves away from the registration edge. Using information obtained during setup, a margin shift is determined that results in a significant reduction in the maximum show through for each image.

Abstract: A color synchronization method and a color laser printer form a color image by forming an electrostatic latent image on a photosensitive body using a laser scanning unit, developing the electrostatic latent image, and transferring the developed image onto a transfer belt. The printer includes a light source which radiates light, a timing belt which rotates the photosensitive body, a plurality of timing displays, which are provided on the timing belt at a constant interval, and on which the light radiated from the light source is incident, and a light receiving portion which detects the light reflected or transmitted by the timing displays. Synchronization for each color is controlled in response to a signal received by the light receiving portion.

Abstract: An image forming apparatus forms on a photoconductive body an evaluation chart including first patterns and second patterns. In the first pattern, with respect to a row of dots formed in a main scan direction by a predetermined light beam, a row of dots formed by a next light beam is shifted in the main scan direction, and in the second pattern, with respect to the row of dots formed in the main scan direction by the predetermined light beam, the row of dots formed by the next light beam is shifted in the main scan direction but in a direction opposite to a shift direction of the first pattern. The evaluation chart includes a first pattern group which is formed by the first patterns which are repeated, and a second pattern group which is formed by the second patterns which are repeated.

Abstract: A printer for executing recording onto media, including a head and a rotary encoder, wherein the head and the media are moved relatively. In the relative movement between the head and the media, the media may be moved relative to the immobile head, or the head may be moved relative to the immobile media. The rotary encoder outputs pulses corresponding to relative positions between the head and the media. The head starts recording onto the media based on the pulses output by the rotary encoder. When the pulses from the rotary encoder have not been output within a predetermined period of time, the printer starts recording onto the media based on a lapse of the predetermined period of time.

Abstract: The write lines of a color laser printer are maintained substantially equal throughout the printer's operation by an electronic control arrangement. At the factory, the write lines on all photoconductors of the color laser printer are calibrated to be substantially equal, and the ratio of each write line to a measuring line for each photoconductor is ascertained. During operation of the printer, the length of each of the measuring lines is periodically determined through counting the number of PELslice clock timing pulses produced from a PELslice clock operating at a fixed frequency determined during factory calibration. The length of the write line is determined by the product of the length of the measuring line and the factory calibrated ratio of the length of the write line to the length of the measuring line.

Abstract: Forming an image by utilizing a scanning device for scanning a color image for each color element, a reading device for reading image data for each scanned line, a rotary polygon mirror for deflecting, in a main scan direction, a modulated light beam that is based on the image data for each read line, so that an image holding member that is rotated in a sub-scan direction is scanned by the deflected light beam and a latent image is formed thereon, a first generation device for determining whether the light beam deflected by the rotary polygon mirror has scanned a predetermined location, and for generating a main scan start reference signal, and a second generation device for generating a sub-scan start reference signal in synchronization with the rotation of the image holding member, a first control device that controls the rotary polygon mirror and the rotary image holding member, so as to maintain a phase difference between the sub-scan start reference signal and the main scan start reference signal, no mat

Abstract: According to a beam control device of the present invention, if an exposure device including a light emitting section is instructed to form an image and a predetermined current is then supplied to an application specific integrated circuit and a main control section, then the main control section outputs an light emitting section on signal. Then, the light emitting section outputs light having its intensity changed according to image information.

Abstract: Described is a method for imaging a printing form (10) using one or more laser diode bars having a number n of individually controllable laser diodes (16) whose imaging spots (20) lie essentially in a row on the printing form (10), for the case that at least one laser diode (16) on the laser diode bar (14) cannot be activated, but a maximum number m of laser diodes (16) whose neighboring imaging spots (20) have a distance a on the printing form (10) are able to be activated. The relative speed between the imaging device (12) and the printing form (10) is increased by the factor (n/m). The exposure time per printing dot (69) is shortened by the factor (m/n). In order to input in each case an amount of energy per printing dot (69) on the printing form (10), imaging is carried out using the m activatable laser diodes (16) with an imaging intensity which is a function of the exposure time and of the specific amount of energy per printing dot (69).

Abstract: An imaging method for a printing form (32) is described, with one or more laser diode bars (10) with n individually controllable laser diodes (12) each of which are assigned to one imaging channel, in which the laser diodes (12) of a laser diode bar (10) are divided into a main field (14) of m and into an auxiliary field (16) of (n-m) laser diodes (12) in such a way that an imaging channel (44) in the auxiliary field (16) with a matching feed that can be activated is assigned to each imaging channel (44) in the main field (14) that cannot be activated. In order to create a row (40) of m printing dots (38) on a setting line (36) at even distances a by means of the imaging channels (44), printing dots (38) are set by the main field (14) at a first time, and by the auxiliary field (16) at least at a second time. The imaging channels (44) are shifted relative to the printing form (32) parallel to the setting line (36) between the imaging times.

Abstract: A photosensitive material in which a fog unnecessary for a photosensitive material is not generated when irradiation of a laser beam and a character or a mark is printed by an array of optically distinguishable dot patterns is provided. When the dot patterns are arrayed by M number in column and N number in row and the character or the mark having a size of A×B is printed, the dot pattern has irregularity of no more than S+10 &mgr;m, and an almost circular shape of no lower than 100 &mgr;m and not more than the smaller diameter either A/M or B/N, when viewed from the emulsion layer side. A surface roughness is set in the range of 0.2 &mgr;m to 1.0 &mgr;m.

Abstract: A method is provided for recording medium having a substrate on which first data and second data are recorded as a protrusion/depression pattern and a reflective layer that is provided on a surface having the protrusion/depression pattern. Laser light is radiated to the reflective layer to change the protrusion/depression pattern of the second data, and third data used for identifying the recording medium is additionally recorded at a predetermined position on the recording medium.

Abstract: On a basis of a frequency analysis of the irregularities in density caused by a subscanning direction feed amount error of an exposure head, subscanning direction intervals between LEDs of the exposure head within the image forming apparatus are unequal such that the irregularities in density generated in an image is generated in high frequency area with a spatial frequency of at least 1 lp/mm. By using such image forming apparatus, an image is formed in which the irregularities in density is sufficiently suppressed in low frequency area with the spatial frequency of less than 1 lp/mm. Even if the irregularities in density is relatively large in high spatial frequency area, human eyes are difficult to view the irregularities in density thus the image quality can be improved.

Abstract: A method of setting a plurality of margins in an electrophotographic machine includes setting a top margin for a reference color black by establishing a first time delay between a vertical synchronization signal and a first line. A right margin or a left margin for the reference color black is set by establishing a second time delay between a horizontal synchronization signal and a start of printing. The other of the right margin and the left margin is set by adjusting a scan speed of a laser beam across a photoconductive element and adjusting a process speed in the cross-scan direction including the speed of the photoconductive element, image accumulation member, and print medium. A bottom margin is set by adjusting the process speed. The other three color planes, cyan, magenta and yellow are then registered or aligned to the reference color plane, black.

Abstract: A method of setting a plurality of margins in an electrophotographic machine includes setting a top margin for a reference color black by establishing a first time delay between a vertical synchronization signal and a first line. A right margin or a left margin for the reference color black is set by establishing a second time delay between a horizontal synchronization signal and a start of printing. The other of the right margin and the left margin is set by adjusting a scan speed of a laser beam across a photoconductive element and adjusting a process speed in the cross-scan direction including the speed of the photoconductive element, image accumulation member, and print medium. A bottom margin is set by adjusting the process speed. The other three color planes, cyan, magenta and yellow are then registered or aligned to the reference color plane, black.