Abstract: An image forming apparatus forms an image by laser beams from a plurality of lasers. The image forming apparatus includes a light amount control circuit that detects displacement in a sub-scanning direction of the main scanning line of a laser beam from the predetermined laser, from a reference position. The apparatus decides an allotted amount of light for each of the plurality of lasers in accordance with the detected displacement and controls to drive each of the plurality of lasers in accordance with the decided allotted amount of light for each laser.

Abstract: A photo-printing system includes a laser exposure unit, a reference clock generation unit, an image input unit, and a controller. The image input unit receives first pixel data and second pixel data to be expressed after the first pixel in accordance with image data. In a first control, the first and second pixels are scanned for exposure in a laser emission region state wherein each of the scan-start timings of the first and second pixels are controlled in accordance with a reference clock. In a second control, the first pixel is scanned for exposure in a nonlinear light emission region state, and the second pixel having a density equal to or lower than a predetermined density is scanned for exposure in the laser emission region state, the scan-start timing of the second pixel is advanced with respect to the first control.

Abstract: The present disclosure includes systems and techniques relating to pulse laser printing. In general, in one implementation, an apparatus includes: a laser operable to produce a pulsed printing beam; an optics assembly operable to focus and direct the pulsed printing beam; and electronics communicatively coupled with the laser and the optics assembly, the electronics being operable to control the laser and the optics assembly to generate power pulses of the pulsed printing beam in synchronization with a series of moves that steer the pulsed printing beam in a non-raster scanning pattern to predefined locations on a material to alter an optical characteristic of the material at the predefined locations, which are arranged to form at least a portion of a symbol. The electronics may deliver the power pulses in synchronization with arrival at the predefined locations, and the electronics may be configured to receive sensed feedback in a closed loop.

Abstract: An image forming apparatus, having a submodule that causes non-uniformity in density in a slow-scanning direction in accordance with rotation, includes a correction image forming unit that forms an image for density correction, in cooperation with the submodule, a density detector that detects a density of the image for density correction, a correction data generation unit that generates correction data to correct a density distribution based on a density distribution of the image for density correction in a slow-scanning direction detected by the density detector, a phase detector that detects a phase of the submodule, and a mark image forming unit that forms a mark image in synchronization with the phase of the submodule detected by the phase detector, in the image for density correction formed by the correction image forming unit.

Abstract: Differing ratios of the amount of light from light source LD2 to the amount of light from light source LD1 are provided. An image pattern for adjustment that includes, for each color, an area made up of isolated dots by light source LD1 and an area made up of isolated dots by light source LD2, is printed for each ratio. In a copier, a density of each area is detected, a ratio at which a difference between the density of an area of isolated dots by light source LD1 and the density of an area of isolated dots by light source LD2 is smallest is decided as an adjustment ratio, and control is performed such that light sources LD1 and LD2 emit light at the adjusted ratio.

Abstract: An image forming apparatus includes: a spindle motor (130) for rotating an optical disk (200); an optical pick-up (100) for applying laser light to the optical disk which moves in a radial direction of the optical disk; a stepping motor (140) for transporting the optical pick-up in the radial direction by a predetermined distance every time the optical disk is rotated plural times; a tracking actuator for actuating a position of laser light irradiated from the optical pick-up; a servo circuit (138) for controlling the tracking actuator in such a manner that irradiation loci of the laser light is made different from each other every time the optical disk is rotated plural times; and a data converter (160) for defining intensity of the laser light in accordance with gradation of dots to be arrayed and a total rotation time of the optical disk.

Abstract: A method and a test form for equalizing exposure heads of an exposer recording printing originals onto a recording material with exposure heads, with regard to the area coverage recorded. Each head contains a laser module generating a laser beam and focusing it onto the material. Each head records a recording band, the laser beams sweeping over the recording material in a main scanning direction while the heads are moved along the material in a secondary scanning direction. A test exposure is carried out, in which each head records a test form having test areas and a background area in its recording band. The area coverage recorded of the background area is compared visually with area coverages recorded of test areas of an adjacent test form and, from differences thereof in adjacent test forms, corrective values for the laser power of the laser modules in the exposure heads are calculated.

Abstract: An image forming apparatus includes light source having multiple light-emitting portions, rotating polygonal mirror which deflects a beam that is emitted from light source, and photosensitive member which is exposed by beams in an image period that is included in one scanning cycle of the beam. One scanning cycle of the beam includes an image period and a non-image period. This apparatus includes selection unit which selects one or more light-emitting portions to be used in image period from among multiple light-emitting portions, and driving unit which drives selected light-emitting portions to emit a beam in a non-image period that is immediately before image period. This apparatus further includes control unit which executes auto light power control for one or more light-emitting portions to be used in image period according to light power of beams detected by beam detection unit.

Abstract: A method for imaging a printing form (10) using at least one controllable light source (42) is described, a number of image spots (20) being generated at a number of positions on the printing form (10) in accordance with image data in a bit field, by the controlled action of light on the printing form (10), the intensity of the light acting at at least one of the positions of the image spots (18) being controlled as a function of the value of a measure for the number of the image spots (24) to be generated in one surrounding area (22) of the position. The method may be implemented in a device for imaging a printing form (10), having at least one controllable light source (42) and a control unit (50) including a processor (52) and a memory unit (54) in such a way that a program for executing the method is stored in the memory unit (54) and may be executed in the processor (54). The device may be used in a print unit (58) of a printing press (60).

Abstract: A photoreceptor cleanerless image forming apparatus and method for overlappingly forming yellow, cyan, magenta, and black toner images and decreasing color mixture or an exposure error due to reverse transfer toner or untransferred toner are provided. The image forming apparatus 100 comprises four image forming units 100a, 100b, 100c, and 100d configured to be photoreceptor cleanerless in a 4-drum tandem manner. Each image forming unit includes a photoreceptor 103a, 103b, 103c, or 103d, a charger 105a, 105b, 105c, or 105d, an exposure apparatus 106a, 106b, 106c, or 106d, and a developing apparatus 109a, 109b, 109c, or 109d. When exposure resolutions Ry, Rc, Rm, and Rk are assumed for exposure sources of the exposure apparatuses in the image forming units which form yellow, cyan, magenta, and black images, respectively, the exposure resolutions are configured to satisfy the conditions of Rk?Rc?Rm and Rm>Rk. This decreases an exposure error (image hysteresis) in an image formed on paper.

Abstract: An electro-optical device includes a controller, a reference current source, a correction current source, a combining unit, and an electro-optical element. The controller generates a reference current control signal defining a first period during which a reference current is output, and a correction current control signal defining a second period during which a correction current is output, the second period being shorter than the first period. The reference current source generates the reference current based on the reference current control signal. The correction current source generates the correction current based on the correction current control signal. The combining unit combines the reference current and the correction current to generate a driving current. The electro-optical element emits an amount of light corresponding to the driving current.

Abstract: A method is disclosed for positioning an optical labeling mechanism substantially close to a particular track of a labeling surface on an optical disk. The method can include the operation of positioning the optical labeling mechanism adjacent to the particular track. A further operation can be measuring a first surface texture of the labeling surface using the optical labeling mechanism. Another operation can involve positioning the optical labeling mechanism adjacent to a different track. A further operation can be moving the optical labeling mechanism from the different track toward the particular track location. Another operation can involve measuring a second surface texture of the labeling surface using the optical labeling mechanism. A further operation can be comparing the first and second surface textures to determine if the optical labeling mechanism is positioned substantially near the particular track.

Abstract: An optical disc recording apparatus can draw an image by radially vibrating a laser beam under stable focus control. A pickup radiates the laser beam onto the optical disc rotated by a spindle motor. A focus servo controller maintains a constant spot diameter of the laser beam on the optical disc by detecting a return light of the laser beam reflected back from the optical disc. An irradiation position controller operates when the pickup opposes a label face of the optical disc for controlling an irradiation trajectory of the laser beam to vibrate in a radial direction of the optical disc while the laser beam runs along circumferential zones defined on a coloring layer of the label face. A modulating section modulates an intensity of the laser beam for forming dots along the circumferential zones so as to draw the image.

Abstract: A method for forming a pixel (20) having a predetermined density onto a sensitized recording medium moving in a length direction energizes a pixel exposure source (14) to begin exposure at the leading edge (34) of a pixel (20) and for a first predetermined time interval. The pixel exposure source (14) is de-energized for a period depending on the predetermined density and on media transport speed, then re-energized at the termination of the period. The pixel exposure source (14) is then de-energized at the end of a second predetermined time interval to terminate exposure at the trailing edge (36) of the pixel (20), whereby spatial dimensions of each pixel (20) are maintained at variable transport speed or density of pixel (20).

Abstract: An image forming apparatus includes a memory which stores test pattern data. The test pattern data are configured for detecting a density of image data formed on a photo conductor. The image forming apparatus includes a laser unit which forms a plurality of test patterns on the photo conductor by utilizing A plurality of first laser powers based on test pattern data stored in the memory. The image forming apparatus includes a detector which illuminates each test pattern formed on the photo conductor by the plurality of the first laser powers, receives each light intensity reflected by the test patterns and provides output values corresponding to each received light intensity. The output values define a range of output values. The image forming apparatus includes a controller which compares each output value with a first predetermined value. The controller determines a laser power to be used based on the first value, when the first predetermined value falls within the range of the output values.

Abstract: An image signal with an overshoot is generated on a positive-going edge of an input image signal with an overshoot producing unit. Then, a light signal with an overshoot is outputted from a recording light source in response to the image signal with the overshoot supplied from the overshoot producing unit. The light signal outputted from the recording light source is applied to scan a photosensitive medium to record an area gradation image on the photosensitive medium.

Abstract: An image forming apparatus which is capable of eliminating density irregularities of an image formed caused by potential irregularities of the photosensitive member when the drum is irradiated by a beam of constant luminous intensity. A laser driver irradiates a beam modulated based on an image signal onto a photosensitive member. A current controller variably controls a driving current for driving the laser driver. A PWM pulse width converter modulates a pulse width of the beam based on the image signal. A potential sensor measures the potential of the photosensitive member after the photosensitive member is irradiated by a beam having a predetermined luminous intensity. A selector causes the current controller to correct the driving current based on low frequency components of irregularities of the potential and changes a modulation coefficient used for modulating the pulse width based on high frequency components of the irregularities of the potential.

Abstract: An image forming apparatus includes: a spindle motor (130) for rotating an optical disk (200); an optical pick-up (100) for applying laser light to the optical disk which moves in a radial direction of the optical disk; a stepping motor (140) for transporting the optical pick-up in the radial direction by a predetermined distance every time the optical disk is rotated plural times; a tracking actuator for actuating a position of laser light irradiated from the optical pick-up; a servo circuit (138) for controlling the tracking actuator in such a manner that irradiation loci of the laser light is made different from each other every time the optical disk is rotated plural times; and a data converter (160) for defining intensity of the laser light in accordance with gradation of dots to be arrayed and a total rotation time of the optical disk.

Abstract: A light amount adjustment method for use in an image exposure apparatus records an image by scanning a photosensitive material with a light beam modulated in accordance with image signal. The light beam has a first light amount level and a second light amount level that is higher than the first light amount level to perform exposure of one dot. The method sets the first light amount level based on the image signal, exposes test patches by displacing a focus position of the light beam on the photosensitive material and changing the second light amount level that is outputted in accordance with changing of the image signal and adjusts the second light amount level such that halftone dot percent fluctuations of the exposed test patches are minimized to set the adjusted second light amount level.

Abstract: In a case of recording (printing) an image including texts and thin lines, the image is printed with an intended thickness without causing a crack in the thin lines. When the CAD mode is OFF in the apparatus proposed by this invention, assuming a pixel value indicative of a printing color component is 8 bits and the maximum value is 255, the value is reduced to, e.g., 90%, before halftoning is performed, and image forming is performed in accordance with the characteristic curve 751 which specifies the relation between the halftoning-processed data and the amount of exposure light. On the contrary, when the CAD mode is ON, halftoning is performed without reducing the pixel value indicative of a printing color components, and image forming is performed in accordance with the characteristic curve 753 which specifies the relation between the halftoning-processed data and the amount of exposure light.

Abstract: There is provided a photoreceptor cleanerless image forming apparatus capable of decreasing color mixture or an exposure error due to reverse transfer toner or untransferred toner. An image forming apparatus 100 according to the present invention comprises four image forming units 100a, 100b, 100c, and 100d configured to be photoreceptor cleanerless in a 4-drum tandem manner. Each image forming unit includes a photoreceptor 103a, 103b, 103c, or 103d, a charger 105a, 105b, 105c, or 105d, an exposure apparatus 106a, 106b, 106c, or 106d, and a developing apparatus 109a, 109b, 109c, or 109d. When exposure intensities Iy, Ic, Im, and Ik are assumed for exposure sources of the exposure apparatuses in the image forming units which form yellow, magenta, cyan, and black images, respectively, the exposure intensities are configured to satisfy conditions of Ik?Ic?Im?Iy and Ik>Iy. This decreases an exposure error (image hysteresis) in an image formed on paper.

Abstract: A visible light characteristic changing layer is formed in a location which can be viewed from a part of a label surface of an optical medium. The optical medium is set on a turntable of an optical disk unit, which may be rotated at a constant angular velocity, while the power of a laser beam is modulated in accordance with image data. The optical pickup operates at a first power level when changing a visible light characteristic of the optical medium to form the visible information and the optical pickup operates at a lower power level when not changing a visible light characteristic of the optical medium. As a result, a visible-light reflectivity of the visible light characteristic layer is changed, thereby forming an image corresponding to the image data on the label surface, A tracking servo operation is turned off while the optical pickup forms the visible information.

Abstract: An imaging apparatus includes an input that receives a stream of image pixels such as high addressable bits, multiple bits per pixel or binary image bits representing an input image and a processor that processes and directs signals to an LED bar that selectively exposes areas of a photoreceptor. The exposed areas of the photoreceptor form a latent image, controlled by the processor, of areas of varied exposure based on surrounding pixels. The processor examines the pixels to determine an image structure beneficially adaptable to varied exposure and selects a pixel for varied exposure, such as increased or decreased exposure or altered timing to apply the pixel.

Abstract: To provide a recording apparatus capable of executing the stable recording not to waste the light energy even when the power/wavelength of the light beam in the recording apparatus, that records the image/characters onto the recording medium like the data by employing the light beam, are changed, the circumstances such as the temperature, the humidity, etc. are changed, and the recording velocity is changed. A recording apparatus comprises a recording medium fixing member for fixing a recording medium that consists of a superposition of a transfer film and a receiver film, a main scanning direction moving device for moving the recording medium fixing member, a laser recording head for emitting a light beam, and a vertical scanning direction moving device for moving the light beam emitted from the laser recording head in a vertical scanning direction that is perpendicular to the main scanning direction, wherein a light intensity distribution of the light beam is almost a rectangular parallelepiped.

Abstract: The method is for setting the line width of recorded image lines of a focused image beam in an exposer. The exposure point has a diameter and an area with a non-uniformly distributed power density. The recording material has a first exposure threshold and is exposed with an energy density near a second exposure threshold that is substantially higher than the first exposure threshold. The recording material can be a photopolymer printing plate. The line width of the recorded image lines is determined from the distribution of the power density over the area of the exposure point by integrating the time variation of the power density resulting from the exposure speed of the laser beam. The line width is set, by changing the diameter of the exposure point and/or by the laser power, such that the line width is substantially equal to the line spacing.

Abstract: A semiconductor fabrication gray level photolithography strategy, in which the energy beam intensities corresponding to each gray level are selected from a set of non-linear, non-monotonic intensities. Rasterized geometric shape edges are defined by associating one or more intermediate gray levels with pixels in at least one row of pixels. The geometric shape is printed or imaged on an energy sensitive layer by modulating an energy beam to the intensity corresponding to the associated gray level, and directing the modulated beam to the pixel location on the layer. The intensities corresponding to the gray levels are selected so as to optimize critical dimension (CD) characteristics and other printing features.

Abstract: An image processing apparatus, comprising: an exposing device for exposing an image forming material so as to form a latent image on the image forming material based on image data; a developing device for developing and visualizing the latent image on the exposed image forming material so as to form an image; a measuring device for measuring the image density of the image on the developed image forming material; a calibrating device for forming a table to define a relation between an image signal and image density on the basis of plural different test image data and measured-image densities thereof; a storing device for storing a characteristic change model indicating a characteristic change of at least one of the exposing device and the developing device with time; a difference calculating device to calculate a density difference on the basis of the characteristic change model between the time of forming the table and the time of forming an image based on image signal of diagnostic image data; and a correcti

Abstract: A method for banding suppression due to vibration in an imager utilizing a light emitting diode (LED) array is disclosed. By characterizing the LED array and knowing the amplitude and frequency of the signal due to vibration which causes the banding, the LEDs' driving currents are modulated in reverse direction corresponding to the banding signal to suppress the banding.

Abstract: A method is provided of modifying pulsed image data signals for controlling an acousto-optic modulator in an image setter system. The method comprises modifying the pulse widths of the image data signals in accordance with predetermined parameters so as to improve the correspondence between the data representing the image and the data recorded on the record medium. Following modification the data signals are supplied to the acousto-optic modulator.

Abstract: A recording method and a recorder for making it possible to eliminate a slight gap occurring every revolution of a drum (rotation gap) and a slight gap occurring for each column of a two-dimensional spot arrangement (column-to-column gap), enabling high-quality image recording with no defects. In the recording method, wherein a plurality of recording elements are arranged in two dimensions consisting of rows in a main scanning direction and columns in a subscanning direction orthogonal to the main scanning direction and are used to record image information or text information on a record medium, the setup value of output energy of either of the recording elements at the ends of the recording elements in the subscanning direction, the length of the spot recorded by the recording element in the subscanning direction or the main scanning direction, or the area is made larger than that of any other recording element and recording is executed.

Abstract: In a scanning optical device having an APC (automatic power control) circuit for controlling an output power of a laser diode, a reference value is determined by sampling saw-tooth wave which varies time elapses. A triggering system is provided to output a trigger signal, and the saw-tooth wave is sampled and held in response to the trigger signal. Based on the sampled and held value, i.e., the reference value and a value corresponding to the output power of the laser diode, an APC operation is performed.

Abstract: A method of adjusting the maximum intensity of a laser exposure mechanism for irradiating laser light to the surface of a photoreceptor to which a uniform potential is being given by a corona discharger. Photoreceptor surface portions are exposed to laser lights of a plurality of laser intensities obtained by coarsely dividing an optional laser intensity, and the potentials of the photoreceptor surface portions are detected (coarse-division potential detecting step). In the vicinity of the laser intensity corresponding to the potential closest to the desired preset potential, the predetermined laser intensity is further finely divided to set a plurality of laser intensities, photoreceptor surface portions are exposed to laser lights of the plurality of laser intensities thus set, and the potentials of the photoreceptor surface portions are detected (fine-division potential detecting step).

Abstract: A hyperacuity printing system for rendering bitmapped image data on a photosensitive recording medium, the bitmapped image data being rendered as an array of pixels across the photosensitive recording medium in a fastscan direction, and an orthogonal slowscan direction. This system includes a data source for supplying grayscale input image data and a scanning device for rendering grayscale output image data onto the recording medium. The scanning device has a device for writing scan spots on the recording medium. Further included in this system is transformation circuitry for transforming the grayscale input image data into grayscale output image data. The transformation circuitry includes a halftoner, a thresholder, and a selection device, where the selection device selects either the thresholder or the halftoner to provide the grayscale output image data.

Abstract: A visible light characteristic changing layer formed from photosensitive or heat-sensitive material is formed in a location which can be viewed from a part of a label surface of an optical disk. The optical disk is set on a turntable of an optical disk unit while the label surface of the optical disk is directed downward. The optical disk and an optical pickup are moved mutually along the plane of the optical disk. In synchronism with the relative movement, the power of a laser beam output from the optical pickup is modulated in accordance with image data, such as characters or graphic images to be printed, and the laser beam is emitted onto the visible light characteristic changing layer. As a result of the visible light characteristic changing layer being exposed to the laser beam, a visible-light reflectivity of the visible light characteristic changing layer is changed, thereby forming a image corresponding to the image data on the label surface.

Abstract: A method of controlling exposure of a medium comprises the step of changing an emission level of a radiation source from a first power to a second power. The second power emits for less time than required by an irradiance profile to traverse a full-width at half maximum of the irradiance profile projected onto the medium along a direction of relative motion between the irradiance profile and the medium. The emission level changes to the first power and emits for less time than required by the irradiance profile to traverse the full-width at half maximum of the irradiance profile projected onto the medium along the direction of relative motion between the irradiance profile and the medium, then the emission level changes to the second power. Brief pulsing of a single binary source can transfer intermediate amounts of thermally transferable colorant from a donor exhibiting a continuous-tone transfer response.

Abstract: A number of new laser patterns are defined by laser scribing the material. This produces new laser patterns which have not previously been known.

Abstract: To provide a recording apparatus capable of executing the stable recording not to waste the light energy even when the power/wavelength of the light beam in the recording apparatus, that records the image/characters onto the recording medium like the data by employing the light beam, are changed, the circumstances such as the temperature, the humidity, etc. are changed, and the recording velocity is changed.

Abstract: Methods of providing lower resolution format data into higher resolution format are described. In one embodiment a first predetermined amount of image data is provided which is to be rendered onto a print medium. The first predetermined amount of image data is provided in a first resolution format. Using the first predetermined amount of image data, the first predetermined amount of image data is replicated into multiple predetermined amounts of data sufficient to provide said first predetermined amount of image data into a second resolution format which is greater than the first resolution format. At least one laser beam in a laser printer system is modulated using the multiple predetermined amounts of data.

Abstract: Methods of providing lower resolution format data into higher resolution format are described. In one embodiment a first predetermined amount of image data is provided which is to be rendered onto a print medium. The first predetermined amount of image data is provided in a first resolution format. Using the first predetermined amount of image data, the first predetermined amount of image data is replicated into multiple predetermined amounts of data sufficient to provide said first predetermined amount of image data into a second resolution format which is greater than the first resolution format. At least one laser beam in a laser printer system is modulated using the multiple predetermined amounts of data.

Abstract: When a multiple-color image is printed by electrophotography unwanted spaces are produces between different colors. These spaces are attributed to non-development of toner caused by the influence of an electric field at the boundary of an electrostatic latent image formed on a photosensitive drum. Accordingly, when data conversion is converted from two-bit data of a bitmap to eight-bit data that are used for modulating a light signal, a pixel of interest and the neighboring 9×9 pixels are stored and the state thereof is determined. If the pixel of interest is a white pixel and the neighboring pixels are all non-white pixels, then the pixel of interest is not left at a value corresponding to white, but is converted to a value corresponding to a potential that will not develop toner. The photosensitive drum is irradiated with a laser based upon the data resulting from the conversion.

Abstract: A method and apparatus for altering a drive signal provided to an image forming element of a printer based on the type of object being printed, e.g., text and/or lineart, halftone, etc., to provide an optimal exposure level for producing the particular object. The apparatus provides an increased drive signal which, for example, provides an increased laser power during text and/or lineart production using a high setpoint and re-normalizes laser power by providing a decreased drive signal which, for example, provides a decreased laser power during halftone production using a low setpoint. This increased power offers improved appearance of text and/or lineart and the re-normalization offers more quantization levels for tone adjustment, better highlight production, and better overall control of tone during halftone production in a write black printer.

Abstract: An exposure energy control unit of an image forming apparatus controls exposure energy density Edot (&mgr;J/cm2) to be applied to an isolated one-dot pattern of image information to satisfy a relation −0.11P+6.4≦Edot/Eline≦−0.2P+10.7 where Eline (&mgr;J/cm2) represents exposure energy density applied to a line pattern of the image information having lines on every second lines and P (&mgr;m) represents dot pitch. Accordingly, image reproducibility of both of a periodic line pattern and an isolated dot pattern can be enhanced without decreasing the film thickness of a photoreceptor even if the resolution is high.

Abstract: An apparatus for scanning with multiple beams emitted from a semiconductor laser by a polygonal mirror, wherein an image is written for each scanning line by each beam of the multiple beams. The apparatus includes an automatic light amount control circuit having: (i) a light amount detecting circuit to detect a light amount of each beam for each scanning line, and (ii) a sampling/holding circuit to sample and hold a control voltage corresponding to the detected light amount of each beam for each scanning line. The automatic light amount control circuit controls the semiconductor laser based on the control voltage held by the sampling/holding circuit so as to control the light amount of each beam to be a predetermined light amount for each scanning line. The apparatus also includes a synchronization control circuit having an index sensor and a light receiving section on which each beam passes.

Abstract: An image forming apparatus includes reading means for converting image light obtained by optically scanning an original into an electric signal. An image signal conversion table converts the image signal from the reading means in response to a property of the image forming system. An image signal generating device generates a reference image signal, and an image forming device forms an image on a recording sheet in response to the image signal. The image is formed on the recording sheet by the image forming device in response to the image signal generated by the image signal generating device, and image light obtained by optically scanning the recording sheet is converted into an image signal by the reading device, and the image signal conversion table is corrected on the basis of the image signal converted by the reading device.

Abstract: There is provided beam diameter control method and device for changing a focused beam diameter of a laser beam, which can increase light utilization without incorporating a complicated and expensive optical or zoom system. In the beam diameter control method and device, an optical path difference equal to or more than a coherence length of the laser beam is applied to a portion of light flux of the laser beam before the laser beam is focused. A transparent plate is provided to apply such an optical path difference. The laser beam is preferably emitted from a longitudinal multimode semiconductor laser the coherence length of which is short. The transparent plate may be a parallel flat plate or ring-like plate placed near the center of the light flux. The transparent plate is preferably placed within the parallel beam portion of the laser beam. The transparent plate may be placed in a divergent beam portion or a convergent beam portion instead.

Abstract: In a laser scan based recording apparatus, laser light from a measuring laser diode is directed to one reflecting surface of a polygonal mirror. The reflected light is detected with a measuring photodiode. The reflectance of laser light is calculated from the detection output of the measuring photodiode and a reference voltage is generated. When the reflecting surface has rotated to the position where the laser light from laser light source scans a photoreceptor drum, the emission output of the laser light source is controlled by a laser output control circuit on the basis of the generated reference voltage. Despite variation in reflectance among the multiple reflecting surfaces of the polygonal mirror, the photoreceptor is scanned with a constant optical intensity of laser light. Since automatic power control is performed at all times, overdriving of the laser diode is effectively prevented to protect it against breakdown, producing consistent and highly reliable laser power control.

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: An image forming device wherein a Gaussian laser beam is scanned imagewise on a photosensitive recording medium by an image forming optical system including an optical filter having such a laser beam filtering pattern that the optical transmittance is a minimum value M of 40-60% at the center thereof and gradually increases from the center in the radially outward direction in a Gaussian distribution mode. The filter has a filtering radius R.sub.f which is a distance between the center and a point on the filter providing a transmittance equal to 100-(100-M)/e.sup.2 % and which is not smaller than 0.9 R.sub.b but not greater than 1.1 R.sub.b where R.sub.b is a beam radius of the Gaussian laser beam.

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.