Abstract: An electrophotographic imaging system produces multiple gray level images and includes a photoconductor and a charger for repetitively charging the photoconductor to a first charge potential. A laser system selectively discharges the photoconductor in accord with applied image data. A first toner is utilized and exhibits a first charge state that is attracted by a first discharge voltage of the photoconductor. A second toner is also used that exhibits a second charge state of the same sense as the first toner, but is attracted by a second discharge voltage of larger magnitude than the first discharge voltage. A processor modulates the laser system to cause the photoconductor to be discharged to the first discharge voltage when only the first toner is to be attracted to the photoconductor. The processor further modulates the laser scanner to cause the photoconductor surface to be discharged to the second discharge voltage.

Abstract: An image forming apparatus forms an image on a medium by using an output device. A pattern signal for forming a predetermined pattern image on the medium is generated, and image forming parameters for the output device are determined on the basis of the density of the pattern image formed on the medium. The determined image forming parameters are transmitted via bidirectional communication to an external computer or other image forming apparatus.

Abstract: A non-impact printer include a print head with a plurality of print elements such as light emitting diodes (LEDs). A driver drives the plurality of LEDs in accordance with logical states of corresponding bits of print data. A non-volatile memory stores energy specifying data. The energy specifying data describes an amount of drive energy that should be supplied to each of the plurality of print elements when each of the plurality of LEDs are driven during the printing. A random number generator generates random numbers. An adder adds the random numbers to the values of the energy specifying data to produce the energy specifying data that fluctuates within a predetermined range. Each of the plurality of LEDs is supplied with an amount of drive energy to in accordance with the fluctuating energy specifying data, thereby rendering the variations in print density of an entire image not detectable.

Abstract: Gray scale printing data with compensation for dispersion is stored in a first shift register, the data is sliced into respective bits and is fetched by means of a second shift register and AND-gates. Standard resistances are scanned by means of a third shift register and switches, in synchronization with the data retrieval, for changing standard current, and light emitting current to light emitting bodies is changed according to the standard current.

Abstract: A method is disclosed for calibrating a grey level recording printhead having a plurality of recording elements. The method comprises measuring a parameter of each recording element, the parameter relating to a recording characteristic of the element, in response to measuring the parameter, defining a set of cells of clock periods having time boundaries to determine a set of K quantized clock periods; defining a subset of one or plural contiguous grey values within a set of J grey values recordable by the printhead for recalculation of a subset k of quantized clock periods wherein the number k of quantized clock periods is less than the number K, and recalculating at least some time period boundaries and clock periods for the grey levels j without changing the K total number of K clock periods.

Abstract: In a method of correcting output light quantities of a plurality of optical output media aligned in one direction in an optical writing apparatus that activates and deactivates the optical output media in multi-gradation to thereby perform optical writing onto an object onto which writing is to be performed, the quantity of light outputted from each of the optical output media is measured, and a variation in the output light quantities of the optical output media is corrected based on a result of the measurement. In performing the correction, in a specific gradation range, correction is performed so that the output light quantities of the optical output media are not made uniform.

Abstract: Printer apparatus and method of forming multiple image pixel sizes on photosensitive media. The printer comprises a light source for projecting a light beam onto the photosensitive media to form the image pixel on the photosensitive media. An aperture system is interposed between the light source and the photosensitive media for adjustably sizing the light beam, the aperture system having an adjustable aperture plate for receiving the light beam therethrough. The aperture system is adjustable for variably masking a predetermined portion of the light beam, so that the image pixel obtains a predetermined size as the predetermined portion of the light beam is masked. The aperture system includes a guide member having parallel spaced-apart grooves therein. An aperture plate, which slidably engages the grooves, has a first aperture of a first size and a second aperture of a second size spaced-apart from the first aperture.

Abstract: Plural linear marks extending along a scanning direction are spaced apart from each other at constant intervals and parallel to each other at a boundary of partial exposure ranges. When the marks are repeatedly formed by two light beams while a position of the mark formed by one of the two light beams is moved in the scanning direction, a density within a predetermined region corresponding to the boundary is changed so as to become lighter as the intervals between the marks are increased. When plural linear marks, which extend along the scanning direction and are spaced apart from each other at constant intervals and parallel to each other at a boundary portion of partial exposure ranges, are formed by two light beams while a position of the mark formed by one of the light beams is moved in a direction perpendicular to the scanning direction, a density within a predetermined region is changed so as to become lighter as an amount of offset is reduced.

Abstract: A method and apparatus for controlling the density of the printed medium of a printer is provided and comprises the following steps. First a control strip is printed on the print medium having at least two coverage patches having a first and second different standard density. Next, the optical density of each of the patches are measured. Next a first and second tolerance limit is determined for the first and second patch, respectively. The next step is to determine whether the measured optical density of the first patch is within a first tolerance of the first standard density. If the first measured optical density is not within tolerance of the first standard density, then a change of at least one printer parameter is calculated such that the first density is corrected within the first tolerance. Then the effect of the change of the printer parameters on the second optical density is determined.

Abstract: In an exposure apparatus for exposing a photosensitive medium using light-emitting elements, correction to account for environmental conditions at the time of exposure that change is performed by dynamically changing the value of current or voltage to be supplied to the LEDs. Thereby, control of exposure duration can be performed solely for expression of multi-gradation levels, so that a very high resolution is not required for the control of exposure duration. Therefore, it is possible to realize a low-price exposure apparatus capable of printing multi-gradation images. For exposure to a single color using a plurality of LEDs, the gradation level to be expressed by the individual LEDs is cyclically changed, so that the construction of gradation level control for each LED can be simplified. Further, since the LEDs can be used at substantially equal duties, the individual variation of LEDs does not evidently show. It is also possible to prevent an inconvenient incident where a particular LED deteriorates.

Abstract: An optical scanning system includes a light source for emitting light beams, a beam deflection unit for deflecting the light beams to sequentially land the light beams along a predetermined scan line, and a light source driving unit. The light source driving unit drives the light source so as to land the light beams on pixel points set at equal intervals along the scan line according to image information by controlling the emission intervals between the light beams and the exposure periods of the respective light beams. The light source driving unit also adjusts the size of spots formed on the pixel points by the light beams according to gray scale values included in the image information. Therefore, in the optical scanning system, gray scale information is expressed by forming the light beam spots of an adjusted size on the pixel points set at equal intervals along the scan line.

Abstract: An image forming apparatus includes a photosensitive drum which is exposed by a line head. The line head includes a fluorescent head having a plurality of individually driveable light points which are aligned in a plurality of sublines in the direction of the width of the photosensitive drum. Respective light points of the fluorescent head are driven by a line driver in accordance with drive data from a shift register which holds the drive data for all the light points. One print line is formed by a set of four sublines. In the case where the thinning of a line width is to be corrected, the print line is formed by sublines generated according to a fattening amount, whereby the line width is fattened. When the apparatus is used as a facsimile or a printer, a fattening amount for a facsimile or a fattening amount for printer is set.

Abstract: A method for defect-correction printing. A spatial light modulator that is used to generate the image is mapped for defects. The ON defects are compensated by setting a background level that is equal to the cumulative exposure of the ON defects, and then this background level becomes the threshold for development by the electrophotographic process. The system compensates for OFF defects by allocating the bits and exposures necessary to approximate the OFF defects to operative elements, thereby keeping the cumulative exposure for that pixel in the final printed image exactly, or as closely as possible, equal to the desired exposure. The corrections are contained in a defect correction module (10) that generates the appropriate patterns with the correct allocations to minimize error.

Abstract: A light source is used in which at least one row of light emitting elements, formed from a plurality of light emitting elements arranged along a predetermined direction, is provided. A plurality of scanning lines is recorded synchronously at one main scan operation and at least one scanning line is formed overlapping with each other in each main scan operation. In order that at least one scanning line is recorded in an overlapping region with the scanning lines overlapping each other by a combination of dots recorded by a preceding main scan operation and dots recorded by a succeeding main scan operation, emission of light from the light emitting elements is controlled based on image data. As a result, even if an error in an amount of movement in a sub-scan direction occurs, linear uneven density does not occur, and therefore, an image of high quality can be obtained.

Abstract: A non-impact printer has a print data correction circuit for providing a print data correction processing for video signals transmitted from a printing control unit to produce correction output data or pattern for printing on the basic raster line and other correction output data or patterns for printing on the sub-raster lines. Those correction output data or patterns are supplied to the print head in the form of a real printing data signal.

Abstract: An image processor includes an input device for inputting image signals, and a correcting device for correcting the image signals. A generating device generates a pulse-width modulation signal responsive to an image signal corrected by the correcting device, and a light emitting device emits light on the basis of the pulse-width modulation signal. A detecting device detects the pulse width of light emitted from the light emitting device, and a setting device sets correction conditions of the correcting device on the basis of the pulse width detected by the detecting device when a predetermined signal is supplied to the generating device.

Abstract: A test page, system, and method are used to set a color density level of a laser printer, by producing a dot gain test pattern. The laser printer has at least one primary color. The dot gain test pattern is self-indicating and thus requires no external reference in order to determine a correct color density level. A preferred embodiment of the dot gain test pattern includes (a) a stable pattern having a color density which is stable with respect to changes in the laser printer operating conditions, and (b) a sensitive pattern having a color density which is sensitive to changes in the operating conditions, wherein the sensitive pattern in reference to the stable pattern indicates the density level of the laser printer for the at least one primary color.

Abstract: A non-impact recording method and apparatus comprises recording grey level pixels using a recording element in accordance with a selectable combination of recording element on-time and intensity wherein at least some pixels are recorded using the recording element so that a pixel of one density is recorded using a different recording element on-time and a different intensity than used for recording a pixel recorded at a second density, the selectable combination being predetermined in accordance with a multi-bit signal representing a grey level of the pixel to be recorded. The recording element also records certain other pixels represented by multi-bit signals that define the same grey level using different combinations of on-time and duration to form pixels of different densities over an image area which pixels tend to average out to the density defined by the multi-bit signal for the certain other pixels.

Abstract: A system controls the laser-induced discharging of pixel-sized image areas on a photoreceptor in a multi-color xerographic printer where multiple layers of toner are placed on the photoreceptor surface. A light collector, disposed to collect light either reflected from or passing through the photoreceptor, detects conditions in which the laser must pass through one or more layers of previously-placed toner to discharge the photoreceptor. When such a condition is detected, the system increases either the intensity or exposure duration of the laser.

Abstract: A method of decreasing toner in solid area development to improve the latitude of a xerographic process in a machine having a projecting system for modulating a beam and projecting an image onto an imaging surface by specifying pixels defining solid image areas and selectively modulating the beam with regard to the specified pixels to change the state of the pixels from black to gray or partial white.

Abstract: A laser beam scanning apparatus and method for providing controllable print density. The laser beam scanning apparatus includes a modulator for modulating a light beam, a rotating polygon mirror for deflectively scanning a light beam which is passed through the modulator, at least one lens unit having at least one lens which is movable to a position on the optical axis and a position completely off the optical axis, and a controller for switching the modulating clock frequency of the modulator and the rotating speed of the polygon mirror together with selective shifting of the at least one lens unit or lens thereof to a position on the optical axis or completely off the optical axis whereby the method effects control of the apparatus for controlling print density.

Abstract: For input image data (`A`) before conversion, each pixel is converted into N (=3) parts. In this case, the three sub-pixels of data corresponding to a recording pixel (black pixel) are converted into recording sub-pixels on both sides of the three (`B`). This eliminates the density variation within a single pixel. Therefore, it is possible to reduce the dot spacing at slanted area, for example, and hence eliminate jaggies, providing a reproduced image easily recognized.

Abstract: An image signal processor of a printer is provided.

Abstract: A method and apparatus for high resolution multibeam scanning at constant line intervals is disclosed, wherein simultaneous transfer of image data is achieved via multibeam scanning. According to the present invention, exposure scanning is accomplished a plurality of times relative to a single image surface of n scan lines. Each exposure scan is accomplished simultaneously relative to the total M lines using M individual light beams. Each of M individual beams are positioned such that there is a distance of M lines between adjacent beams. Each individual laser beam is used for exposure scanning of mutually different lines. Therefore, the scan lines of the various beams in a next scan cycle are apart (M-1) lines from the scan lines in the previous scanning cycle. In one embodiment of the invention, an image memory controller reads out image data from an image memory in the scan sequence rather than in the line array sequence.

Abstract: The method of the invention provides an improved method for converting primary printer color values to combinations of the primary printer color values and black to achieve improved printer output color representations. The method includes the following steps. A first balanced set of primary printer color combinations (e.g., CMY) is initially derived which provides a balanced gray representation at various levels of primary color concentration. A second balanced set of primary printer color combinations (e.g., CMYK) is derived which provides a balanced gray representation at various levels of color concentration. Next, a set of primary printer colors (CMY) with K is derived, using the first balanced set, which best represents shadow colors, and a maximum color value is chosen therefrom. Then, a similar set of primary printer colors is calculated which best represents highlight values, by interpolating from the chosen maximum color value to a white value.

Abstract: Disclosed is a laser scanning unit for emitting a laser beam which scans on a surface to be scanned within a predetermined scanning range. The laser scanning unit has a laser diode, and a laser diode controller for controlling the laser diode to emit the laser beam. The laser beam has an intensity corresponding to one of a predetermined graduation steps within a intensity range defined by a first intensity and a second intensity greater than the first intensity in accordance with an image data. The laser scanning unit is further provided with a controller which is capable of shifting the intensity range by changing the first and second intensities.

Abstract: An LED printer includes a printing control unit and an LED head. When a video signal received at the control unit has a higher resolution than the LED head, the control unit carries out the logical AND between successive bit data of the video signal to convert the video signal to a first signal. Corresponding to a line timing signal, this first signal is transferred as a head data signal to the LED head and is then printed on a basic raster scanning line. Further, the control unit also carries out the exclusive-OR between the successive bit data of the video signal so that the video signal is converted to a second signal and outputted to a line buffer. Corresponding to an additional line timing signal, the second signal is transferred as another head data signal to the LED head and is printed on an additional raster scanning line. The LED head drive energy for performing printing along the basic raster scanning line is set independently.

Abstract: A pixel array driver for applying gray level voltages to a group of pixels without the use of a ramp voltage generator employs an integrated circuit arrangement which multiplexes a plurality of discrete gray level voltages in staircase fashion onto a high-voltage bus, identifies each of the discrete voltages appearing on the high-voltage bus with a code word applied to a code word bus, and matches for each pixel the word on the code word bus to a previously stored data word that designates the gray level intensity voltage desired at the pixel. When the code word and the data word match, the pixel is disconnected from the high-voltage bus. Each pixel is provided with a sample and hold circuit to maintain the value of voltage reached after being disconnected from the high-voltage bus.

Abstract: In a image processing system for an electrophotographic printer, a density selective circuit selects density data of a pixel to be corrected in response to the black-and-white patterns of surrounding pixels in a line matrix, and a density correction operation circuit outputs a picture signal with corrected density data corrected by the selected density and other density correction coefficients, thereby the toner adhesion amount, i.e., the printing density is made uniform and a clear printed picture without density unevenness can be obtained irrespective of the content of the picture signal.

Abstract: An optical writing device by which an image with desired tone can be obtained. The optical writing device includes a write head and a modulation unit. A time for scanning of one picture element is divided into some periods by the modulation unit. The modulation unit judges whether the picture element will be in an imaged region or in a blank region and whether the picture element must be provided with a supplementary exposure value. The picture element will be provided with an accumulated exposure value corresponding to a desired level of tone by being provided with the supplementary exposure value by order of the modulation unit.

Abstract: A digital LED printer having a printbar control architecture that enables multi-exposure levels and multiple gray levels for a LED printbar. Alight emitting diode printbar is aligned in an image exposure relationship with a photoreceptor. Video data signal comprised of multiple bits for each pixel are applied to a register/latch. The individual bits of the latched multiple bits for a pixel are applied to AND gates. Those signals are ANDed with multiple strobe line signals that are related to the status of the printer. The outputs of the AND operation are applied to an OR gate. The output of the OR gate is used to control the illumination from a light emitting diode. Beneficially, the characteristics of the light emitting diode are measured and stored such that the current applied to the light emitting diode can be adjusted such that the illumination from the light emitting diode is at a predetermined value.

Abstract: A non-impact printer apparatus and method employs a printhead including a plurality of recording elements and drivers for driving respective recording elements in response to data relative to respective corrected exposure times for recording respective pixels. A first data storage device stores data relative to associating sets of respective recording elements with respective bins. The first data storage device is responsive to first input signals identifying respective recording elements and outputs second signals relative to respective bin assignment numbers for the respective recording elements. A second data storage device is responsive to the second signals for outputting data relative to corrected exposure times for recording respective pixels by respective recording elements. The bin assignment determination for recording elements are established by propagating exposure error calculated from an adjacent respective recording element.

Abstract: Disclosed is a color printer including an image bearing member having an imageable surface for movement along a preselected path, at least a first imaging assembly for forming sets of multiple black toner registration marks on different areas of the imageable surface, and for forming second sets of multiple non-black toner registration marks corresponding respectively to black marks in each set of the first sets of black marks so as to create a series of sets of multicolor registration marks. Each of the second sets is formed thus in accordance with a predetermined different condition of image misregistration relative to the corresponding first set of black toner marks.

Abstract: An image forming apparatus includes an exposure unit forming a latent image using a light from a light source, a developing unit forming a toner image by visualizing the latent image using a toner, a detector outputting a detection signal by optically detecting an amount of toner of the toner image, a memory storing an optimum value of the detection signal output from the detector with respect to a light emission time of the light source, with respect to a plurality of light emission times of the light source to thereby store a plurality optimum values, and a control unit controlling the light emission time of the light source by calculating a light emission time corresponding to a value of the detection signal output from the detector based on the plurality of light emission times stored in the memory.

Abstract: A print head for non-impact printer is, for example, an LED head which comprises a plurality of light-emitting elements, LED drivers for selectively causing a drive current to flow into the light-emitting elements on the basis of the print data, a non-volatile memory for storing the modification data related to the value of the drive current. The modification data are determined in advance at the manufacturing process on the basis of the measured result when the light-emitting elements were driven by the LED driver so that all the light-emitting elements emit substantially same amount of light at the printing operation.

Abstract: A method of reducing EMI when printing an image with a printer having a laser includes determining edge pels located near an edge of the image, determining interior pels located within the image and not edge pels, forming edge pels by operating the laser at a first duty cycle and forming at least a portion of a plurality of interior pels by operating the laser at a second duty cycle longer than the first duty cycle. Another aspect is a method of reducing EMI in a printer when forming a latent image on a photoconductive member by gating a light source ON and OFF, including the steps of identifying a first region near an edge of an image to be formed, the first region being formed by gating the light source at a first frequency; and identifying an interior region of the image to be formed, the interior region being formed by gating the light source at a second frequency lower than the first frequency.

Abstract: A non-impact printhead having a plurality of driver IC chips and and a plurality of recording elements such as LEDs. Each driver IC chip includes a plurality of current-carrying channels that are operative for carrying current to respective recording elements on the printhead and a control for controlling operation of the driver.

Abstract: A halftoning method characterized by two nonaligned halftone screens, one for black and the other for the subtractive primary colors cyan, magenta, and yellow, produces multi-color images on a color laser printer. The black screen is the inverse of, i.e., in reverse fill order to, the subtractive primary colors screen. The halftone pattern is a vertical line screen. In a preferred embodiment, the cells are grouped on hexagonal centers and aligned along X and Y coordinate axes. The dots are grouped in the linear direction of print medium motion. The grouping of dots reduces the effect of halftone screen misregistration, and the cell alignment in X and Y results in fewer high frequency artifacts. Inverting the black screen increases the number of possible chromatic mixed colors that include black, increases color uniformity and reduces the frequency of white "holes" in the printed images.

Abstract: A method of reducing the effects of aliasing. Pixels are divided into phases, such that a phase or combination of phases may be printed to provide one of a number of dot shapes for each pixel. When a pixel is partly overlapped by an object to be printed, that pixel's dot shape is determined by determining which dot shape is the best geometrical match with the overlap. (FIGS. 3 and 7). Then, a greyscale value is determined for the selected dot shape by determining what greyscale will provide an effective greyscale that substantially corresponds to the percent of overlap by the object with the pixel. An alternative method selects a greyscale value for each phase rather than for the entire dot shape.

Abstract: Apparatus for estimating LED printhead junction temperature as a function of an input data stream, and for automatically compensating the printhead drive signal to maintain proper printer calibration to provide junction-level compensation for efficiency loss of an LED as the LED warms due to thermal energy generation from an electrical drive current is effected by a plurality of selectable LED temperature-specific look up tables constructed for a plurality of different LED temperatures. The selected look up table produces an output for driving the LED when the selected look up table is accessed by the input data. A model of the thermal characteristics of the LED, its heat sink, and the structure attaching the LED to the heat sink is adapted to produce an estimate of the temperature of the LED as a function of the image data. An address decoder selects one of the plurality of look up tables to process the input data stream in accordance with the estimate produced by the model.

Abstract: Bit data of a received video signal is partially converted into a first signal representing a data sequence corresponding to the resolution of an LED head. The remaining bit data of the received video signal, which are not converted into the first signal are converted into a second signal representing another data sequence corresponding to the resolution of an LED head. The LED head includes a resolution conversion circuit which converts the video data into the first signal and the second signal. The signals are stored in a shift register having a plurality of line buffers. The first signal is printed on a basic raster line and the second signal is printed on an additional raster line. An LED head drive energy with which basic raster lines are printed and another LED head drive energy with which additional raster lines are printed are set independently of each other.

Abstract: A non-impact printer apparatus includes a printhead having a plurality of recording elements. The printhead further includes a non-volatile memory that stores prebinned data representing recording characteristics relative to the recording elements. The prebinned data includes (a) data associating respective recording elements with respective bins; and (b) data relative to a characteristic of each bin. A controller means is located off of the printhead for generating tables for correcting for non-uniformity of the recording elements. The controller uses the prebinned data for generating the tables.

Abstract: In an apparatus for forming an image on a recording medium by using a group of recording elements including a plurality of recording elements aligned in an array form of at least a single line, a controller controls each recording element so as to be driven plural times for each pixel in accordance with image data and controls the plurality of recording elements in such a way that while one group of the plurality of recording elements is in an operable condition as working elements, neighboring recording elements located next to the working elements are controlled to be in an inoperable condition as non working elements.

Abstract: A line width controlling method for controlling a line width of a toner image includes adjusting pulse width signals for controlling light beam emission of a laser beam generator; forming a latent patch image, comprised of plural latent line images, on a photoreceptor by irradiating a light beam from the laser beam generator; and developing the latent patch image with toner so as to form a toner patch image comprised of toner line images. The steps of forming the latent patch image and of developing the latent patch image to form the toner patch image are both repeated for a plurality of times. The toner patch image at each time of forming has a different gradation from that at other times of forming, so that a series of toner patch images is formed on the photoreceptor.

Abstract: Apparatus and method for performing a photographic printing in which photographic signals are separated into a black signal and a chrominance signal and gradating is performed on each one of the black signal and the chrominance signal.

Abstract: Higher quality printing is difficult in implementation in spatial light modulator printers. The two major problems are accomplishing gray scale within the line time constraints, and eliminating staircasing artifacts within the images printed (81). It can be improved by using an alternate way of resetting cells on the spatial light modulator when data is being loaded onto the cells, timing delay (86), horizontal offset (84), and differently sized pixels (80, 82).

Abstract: A printing system for printing several types of data on the same page, regardless of any differences in spot density between data types. This circuit provides a separate channel for each data type and processes each data type according to its own instructions and parameters (halftones, compressed images, font generation, etc) and according to its own spot density, without there being a necessity for there to be any synchronous relationship between x and y spot densities of the plurality of data types. Each channel has a boundary checker to determine whether the data is within the image boundary by comparing the x/y coordinates of the scanning beam to the input boundary data, and a data converter to convert the data according to its own instructions. Finally, the output of the channels is combined to form the data stream that is sent to the printer.

Abstract: The present invention is directed to a laser printer including a printer controller, a printhead including a plurality of lasers formed in an array for receiving modulating image data from the printer controller, a variable magnifying means such as a zoom lens, and a drum on which a receiver member is mounted on which an image is to be printed. The printer controller is arranged to selectively use any one of a set of predetermined microdot matrixing values and a separate sub-microdot matrix associated therewith, and distribute image data to the plurality of lasers based on such microdot and sub-microdot matrixing values. The variable magnification means (e.g., a zoom lens) applies optical magnification or demagnification to light beams from the array of lasers to provide selective variable microdot matrixing values between the predetermined microdot matrixing values of the set.

Abstract: Bit data of a received video signal is partially converted into a first signal representing a data sequence corresponding to the resolution of an LED head. The first signal is transmitted to the LED head in the form of a real printing data signal that is to be printed on a basic raster line in synchronism with a line timing signal. The remaining bit data of the received video signal, which are not converted into the first signal, are converted into a second signal representing another data sequence, and then stored in a line buffer. The second signal stored in the line buffer is transmitted to the LED head in the form of a real printing data signal that is to be printed on an additional raster line in synchronism with an additional line timing signal. The LED head drive energy with which the basic raster lines are printed and another LED head drive energy with which the additional raster lines are printed are set independently of each other. The LED head may be provided with such a resolution function.

Abstract: A circuit for generating strobe signals to one line light emitting diode arrays of an light emitting diode print head, comprises: a portion for generating a start signal in response to a clock signal, a start pulse, and a synchronization pulse of a central processing unit; a counter for generating a counter signal indicative of counts of the clock signals initiated in response to the start signal; a comparator for comparing the counter signal and strobe period selection signals indicative of a selected period of the strobe signals, and for generating a comparator signal indicative of the comparison; a clock controller for generating a gating clock controlling length of the strobe signals by latching the comparator signal; a signal output portion for generating individual ones of the strobe signals in response to strobe control signals, the strobe signals having lengths determined by the gating clock; and a strobe controller for generating the strobe control signals by latching the gating clock received from t