Abstract: A method and apparatus for expanding a color gamut of a direct thermal printer is described. The method includes, in a three-color direct thermal printer having at least a print head, the print head including print head elements, dynamically adjusting a duty cycle of at least one of the colors depending on the color to be printed in each pixel of an image.

Abstract: An image forming method exposes a surface of an image bearer with light according to an image pattern including an image portion to form an electrostatic latent image, and includes: setting, among pixels constituting the image portion, at least a group of pixels existing at a boundary with respect to a non-image portion as a non-exposure pixel group, and at least a group of pixels existing at a boundary with respect to the non-exposure pixel group as a high power exposure pixel group; specifying, among the pixels constituting the image portion, a predetermined pixel as a target pixel, and a group of pixels existing at a boundary with respect to the non-image portion close to the target pixel as a boundary pixel group; and specifying a light power value of the target pixel based on image identification information acquired from the pixels constituting the image portion.

Abstract: An image forming apparatus includes a drive signal generating unit that generates a drive signal for driving a light source based on a reference pulse signal serving as a reference to form a plurality of pixels arranged in the main-scanning direction of an image, and the drive signal generating unit generates the drive signal by adjusting the pulse width of the reference pulse signal so that the amplitude of portions of the reference pulse signal with the adjusted pulse width corresponding to specific pixels among the pixels is larger than the amplitude of portions corresponding to normal pixels that are pixels other than the specific pixels among the pixels, and so that the pulse width of the portions of the reference pulse signal with the adjusted pulse width corresponding to the specific pixels is smaller than the pulse width of the portions corresponding to the normal pixels.

Abstract: An image forming method forms an electrostatic latent image corresponding to an image pattern including an image portion and a non-image portion by exposing a surface of an image bearer with light according to the image pattern. The image portion includes a plurality of pixels. Among the pixels constituting the image portion, at least a group of pixels existing at a boundary with respect to the non-image portion is set as a non-exposure pixel group. Among the pixels constituting the image portion, at least a group of pixels existing at a boundary with respect to the non-exposure pixel group is set as a high power exposure pixel group where exposure is performed with light of a higher light power value than a predetermined light power value required for exposing the image portion.

Abstract: A medical device includes an array of electrodes, configured for implantation in contact with tissue in an eye of a living subject. Driver circuitry is configured to drive the electrodes in an alternating pattern, such that different groups of the electrodes are driven to stimulate the tissue during different, predetermined respective time periods. A power sensor, may be coupled to deactivate a first group of the electrodes when the available electrical power drops below a predetermined threshold, while a second group of the electrodes remains active. Other embodiments are also described.

Abstract: A pulse width modulation technique is disclosed for use in an image forming device such as a laser printer or a photocopier. The technique implements a pacer to synthesize the frequency of a serializer circuit by stretching (or shrinking) pixel pulse train data. The pacer stretches the pixel pulse train data in accord with increment data that is based upon information about the image forming device, such as the number of bits in the pixel pulse train data, the number of bits in print engine pulse train, the target print engine frequency, and the serializer frequency. The technique can be implemented with digital circuits that provide digital test data.

Abstract: An image forming apparatus comprises a light source, a photosensitive member and a control unit. The light source turns on in response to a driving current supplied based on image data. An electrostatic latent image is formed on the photosensitive member by exposing the photosensitive member to a light beam output from the light source turned on. The control unit controls the value of the driving current supplied to the light source in accordance with a driving state of the light source so that the value of the driving current supplied to the light source differs and changes with the passage of time in accordance with the driving state of the light source prior to the driving current being supplied to the light source.

Abstract: Various systems, methods, and programs embodied in computer readable media are provided for calibration of at least one half-tone density in a printer. In one approach, a method is provided comprising the steps of acquiring a plurality of half-tone density values from a respective plurality of test patches generated on a belt in the printer over a period of time, each of the test patches embodying an intended half-tone density, generating a mathematically smoothed half-tone density value from the half-tone density values, and calibrating a half-tone density in the printer based upon the mathematically smoothed half-tone density value.

Abstract: A pulsed electric operating current that rises during a pulse duration is generated for operating at least one radiation-emitting semiconductor component. For this purpose, in a method for producing a control device for operating the at least one radiation-emitting semiconductor component, a temporal profile of a thermal impedance representative of the at least one radiation-emitting semiconductor component is determined. A profile of the electric operating current that is to be set is determined depending on the determined temporal profile of the thermal impedance. The control device is furthermore designed such that the profile of the operating current that is to be set is set in each case during the pulse duration.

Abstract: A disclosed control device includes a first unit configured to generate image data of multiple images to be superposed one on the other to form a single image and transmit the image data. The second control unit transmits to the first control unit a horizontal sync reference signal for achieving synchronization of the images in a horizontal direction. Based on the horizontal sync reference signal, the first control unit transmits to the second control unit a transfer clock signal that indicates transmission timing of the image data and an effective area signal that indicates an effective area of the image data. The first control unit asserts the effective area signal for an effective-area-signal assertion period that occurs between two consecutive reference-signal assertion periods during which the horizontal sync reference signal is asserted.

Abstract: It is determined whether a low density area in which pixels having density less than a predetermined density exist in succession is included in an image signal or not, and if the low density area exists, an image is formed by irradiating the laser light in a first condition for a pixel to be interested in each pixel area within the low density area and irradiating the laser light in a second condition being different from the first condition for other pixels in the pixel area. In this way, it is possible to improve reproducibility of a highlight area in a high resolution image and improve reproducibility of characters and line images or the like.

Abstract: An image data processing section subjects input image data to image processing, and outputs first to fourth image data. First to fourth pulse width modulation circuits are PWM circuits in each of which a plurality of reference positions are set in one pixel, and output pulses corresponding to the first to fourth image data. A synthesis circuit synthesizes the pulses output from the first to fourth pulse width modulation circuits, and a laser emits a light beam in accordance with the synthesized pulse.

Abstract: An image forming apparatus is provided, including an electrostatic latent image bearer; a charger charging the electrostatic latent image bearer; an irradiator irradiating the electrostatic latent image bearer with image wise light having an image resolution not less than 1,200 dpi to form an electrostatic latent image thereon; an image developer developing the electrostatic latent image with a toner to form a toner image on the electrostatic latent image bearer; a transferer transferring the toner image onto a recording medium; and a fixer fixing the toner image on the recording medium, wherein a time for a given point on the electrostatic latent image bearer to travel from a position right in front of the irradiator to a position right in front of the image developer is shorter than 50 msec and longer than a transit time of the electrostatic latent image bearer.

Abstract: A method for printing multiple binary bitmaps (10) with an original density level (12a) and a color (18), wherein the color (18) is the same for all the multiple binary bitmaps (10), by combining “n” number of binary bitmaps into “p” bits of a multibit image forming a “p” bit image (20), identifying at least one overprint (24a), predicting an overprint density (26a) for each overprint, calculating a set of exposures (28) needed to image each overprint density (24a) and original density (12a), setting a maximum exposure level (30) that is a number greater than or equal to the maximum of the set of exposures (28), calculating pulse width modulation levels (30) for the set of exposures (28) using the set maximum exposure level (30), and printing the color (28) at the set maximum exposure level (30) using the pulse width modulation levels (30) for each level of the “p” bit image (20) in a single pass.

Abstract: An 8-bit (256 gradient) image is represented using a driver IC of 6-bit (64 gradient) construction to drive a plurality of arrayed optical shutter elements. The image data are divided into 64 gradient sections, synchronized by shift clock signals, and transmitted in four cycles to the shift register. The optical shutter element is not turned OFF at the 64th pulse, but is continuously driven without transmitting to the comparator the standard clock signal of the 64th pulse, which controls the ON time of the optical shutter element. In this way, an image of a higher number of gradient levels can be represented using a driver IC of a low number of bits, thereby providing a solid state scanning type optical recording device which suppresses noise generation by reducing the load on the driver IC when driving at multi-level gradient.

Abstract: A laser imaging device is described. The laser imaging device includes a laser driver, and a pulse width modulator system. The pulse width modulator system includes a first pulse width modulator having a first operating frequency and a second pulse width modulator having a second operating frequency, which provides to the laser driver a pulse width modulated output signal having a desired modulation frequency greater than the first and second operating frequencies.

Abstract: Exposure of a medium is controlled by 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 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: The invention concerns a clock-generating circuit, which generates dot clock pulses for driving a light-emitting element employed in an optical-writing section of an image-forming apparatus and has a function of canceling f&thgr; property errors caused by a f&thgr; lens employed in the image-forming apparatus. The clock-generating circuit includes a digital-delay dot clock adjusting section to adjust timings of rising-edges or falling-edges of the dot clock pulses generated by changing a selection for a plurality of delayed-clock pulses, which are generated by delaying clock-pulses, outputted from a reference oscillator, in slightly different delay times; and a controlling section to control a selecting operation for the plurality of delayed clock pulses, performed in the digital-delay dot clock adjusting section, so as to compensate for f&thgr; property errors caused by the f&thgr; lens employed in the optical-writing section.

Abstract: A color image forming method, including the steps of: charging a front surface of a photoreceptor; conducting image wise exposure onto the charged front surface from a rear surface of the photoreceptor so that a latent image is formed on the front surface; developing the latent image with a color toner so that a color toner image is formed on the front surface; and repeating the steps of charging, conducting image wise exposure and developing so that a multicolor toner image is formed on the front surface; in which a secondary color of the multicolor toner image, which consists of two color toner images, is formed in a manner that the two color toner images are formed by conducting the image wise exposure at a same exposure amount; and the first one of the two color toner images is formed by conducting the image wise exposure at an exposure amount which creates a potential smaller than that of already formed primary color of the multicolor toner image, which consists of single color toner image.

Abstract: A printer employing a scanning electrostatic print head includes a sensor to determine dimensional variations in a printable dielectric material, such as paper, on which a latent electrostatic image is disposed. A charge deposition delay circuit is in electrical communication with the scanning print head which allows properly positioning the electrostatic image on the dielectric material to compensate for the dimensional variations.

Abstract: An image forming apparatus and an image forming method in which a latent image is formed by scanning the surface of an image bearing body with a laser light blinking in accordance with pulse-width modulation based on an image signal. Output-control-wave generating device generates an output control wave having a peak for a write time of each picture element. The output control wave is turned on and off by a gate circuit with timing determined by an exposure control signal generated by exposure control device. A signal output by the gate circuit is converted by a V/I converter into a driving current wave for controlling radiation of a laser light by an exposure unit. In this way, exposure energy produced by the exposure unit can be concentrated on an exposure time duration of each picture element, allowing the amount of mutual interference among picture elements to be reduced.

Abstract: An image forming apparatus includes a photosensitive member; an exposing device for emitting a beam of light in accordance with image data for forming an electric image on the photosensitive member; a plurality of developing devices for developing the electric image formed on the photosensitive member; a controller for controlling, for each picture element, duration of the beam of light emitted from the exposing device in response to an image signal; wherein the controller varies, for each picture element, a maximum value of the duration of the beam of light emitted from the exposing device, depending on which developing device is used.

Abstract: A hyperacuity printing system for rendering image data on a recording medium, the image data being rendered as an array of pixels across the recording medium in a fastscan direction, and an orthogonal slowscan direction. The system includes a data source for supplying grayscale input image data and a scanning device for rendering grayscale output image data, the scanning device having a writing device for writing scan spots on the recording medium at a writing pitch in the slowscan direction and a writing pitch in the fastscan direction. The system also includes transformation circuitry for transforming the grayscale input image data into grayscale output image data, the transformation circuitry including 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: An image forming apparatus which can form gray-scale images comprises a pulse width modulation device for outputting a pulse width modulation signal according to image data, a light emitting device for emitting modulated light in response to the pulse width modulation signal outputted from the pulse width modulation device, a detecting device for detecting quantity of the modulated light, a current control device for controlling, at a time when the light emitting device emits modulated light continuously, current to be supplied to the light emitting device in accordance with the quantity of light detected by the detecting device, and a condition control device for controlling a condition of the pulse width modulation device according to the quantity of light detected by the detecting device at a time when the light emitting device emits the modulated light according to the pulse width modulation signal.

Abstract: In a digital image forming apparatus, when a latent image is formed on a photoconductor, a light from a light source is emitted in a period of a duty ratio while modulated according to image data, and the latent image is developed and transferred onto a sheet of paper. The duty ratio, defined as a ratio of a light-emitting time of a light exposing the photoconductor to a period for exposing a dot, is changed in the same document according to dot information on the document such as an edge signal. In the modulation of the optical intensity, the light emission onto the photoconductor is performed with a duty ratio which may be set for each dot. Image portions formed with different duty ratios may exist at the same time in a reproduced image. For example, an edge portion in a document is reproduced at the duty ratio of 100% while a non-edge portion is reproduced at the duty ratio less than 100%.

Abstract: An image forming apparatus in which two delay time generators input data for two delay times, and a reference signal, and outputs two pulse signals having predetermined pulse-widths. A pulse generator generates a pulse signal based on the phase difference between the two output pulse signals. The pulse-width and pulse position of the generated pulse signal is arbitrarily controlled by the two output pulse signals.

Abstract: A raster output scanning system is disclosed which modifies a train of pixel information used for modulating a light beam to improve the image contrast. In this invention, all the On pixels which have at least one transitional edge will be modified in such a manner that the pulse width of the modified pixels will be shorter than the allocated pulse width for each pixel and the pulse amplitude of the modified pixels will be higher than the amplitude of the unmodified pixels. However, the product of the pulse width and the pulse amplitude of the modified pixels are equal to the product of the pulse width and the pulse amplitude of the unmodified pixels. The modified train of pixel information of this invention creates an exposure profile on the photoreceptor plane with less smearing effect and less variation of the pixel width in accordance with the variation of the xerographic threshold.