Abstract: Forming dots on a photosensitive material by irradiating the photosensitive material with a laser beam having a pulse width S (sec) and energy density E (w/cm.sup.2), wherein the pulse width S and the energy density E are within the region bounded by the following formulas:log E=-0.46 log S+3.68log E=-0.46 log S+2.

Abstract: In a digital image forming apparatus, when a latent image is formed on a photoconductor by modulating optical intensity of laser beam, the laser beam is emitted in a period of a duty ratio while modulated according to image data, and the image is formed on a sheet of paper. This process is repeated for four colors for a color document. 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. For example, the light emission timing pattern is changed between odd and even lines. In another example, the light-emission timings may be changed at least for one of the reproduction colors. The light-emission timing patterns may be provided for each of reproduction colors. The light-emission timing patterns may be changed to have a constant or different screening angle between colors. Image quality of a half-tone image is improved by using such patterns.

Abstract: There is provided a control method of a microfilm image reader, in which a scanner reads an image in a frame recorded on a microfilm and supplies image data of the read image to a printer, for printing out image data of an original image faithfully in a relatively easy processing even if the original image largely contains middle tone portions, without either calculating a threshold value for binarization by a complicated method or performing a special image processing to be uniquely performed to a binary density image. The scanner reads the image in a multi-tone gradation and the printer prints out image data of at least one portion of the read image in the multi-tone gradation. When the image in a frame contains both a multi-tone gradation portion in a photograph area and a binary density portion in a document area, image data of the photograph area and image data of the document area are printed out in the multi-tone gradation and the binary density or gradation, respectively.

Abstract: The present invention is a method and apparatus for compensating for position error inherent in a raster output scanning printing system by adjusting the intensity of image exposure to effect a correction in the output image. The invention is particularly well suited to compensate for position errors arising from a plurality of sources by first summing the errors and then applying a single compensating adjustment to the intensity of individual scan rasters based upon the position error thereof.

Abstract: A laser scanning device emits a scanning laser beam which scans a predetermined surface to be scanned to form an image consisting of a plurality of pixels on the surface. The laser scanning device determines the intensity of the laser beam for each pixel of an image to be formed, and executes a feed-back control of the laser diode so that the intensity of the laser beam for each pixel accurately corresponds to the gradation level thereof.

Abstract: A laser printer provides a photoreceptor and a laser which produces an optical beam. A modulator is coupled to the laser and is responsive to binary data values to apply modulation signals to the laser to cause an image-wise modulation of the optical beam. Scan apparatus repetitively scans the optical beam across the photoreceptor to induce an image-wise charge state thereon. The scan apparatus causes, for one of the binary values, a variation in charge states corresponding to the one binary value across the photoreceptor. A function generator applies correction signals to the modulator to alter the optical beam in such a manner as to substantially prevent the variation of charge states. The function generator either causes a modulation of the voltage bias applied to the laser or modulates its pulse width output.

Abstract: An apparatus and method for printing graphic images by laser thermal transfer uses a laser source and a programmable pulse generator to transmit a pulsed infrared laser beam in accordance with a printing program of image data to print graphic images on sheet material. The pulsed laser beam is transmitted through a focusing lens, and the focused beam is in turn scanned by a scanning device through a laser window assembly into an ink web along a line of laser impingement. The ink web contains a layer of printing ink and overlies the sheet material supported on a roller platen. The laser window presses the ink web into the sheet material against the roller platen along the line of laser impingement to facilitate the transfer of ink from the web to the sheet in accordance with the printing program of image data.

Abstract: An image output apparatus such as a laser printer in which, in the case where the write density is changed, the light quantity is controlled by using a period when the rotational speed of a polygonal mirror is changed. In the apparatus, when an instruction for switching the write density is issued and the rotational speed of the polygonal mirror is set to be a changed value, a laser beam forced turn-off signal generating circuit generates a laser beam forced turn-off signal having a turn-off period which corresponds to the rotational speed of the polygonal mirror. During the period when the rotational speed of the polygonal mirror is changed, a laser beam light quantity controlling circuit controls the light quantity of the laser diode so as to have a value corresponding to the changed write density. Even during a period when the rotational speed of the polygonal mirror is changed, therefore, the light quantity can be controlled without exposing the photoreceptor to light.

Abstract: An ink amount correction system is provided in a color image printer system for printing a full color image by mixing yellow, magenta, cyanogen and India ink amount signals. The ink amount correction system includes: a plurality of color ink amount correction circuits which include a quantization section for quantizing a color ink amount indicative signal representative of the amount of an ink of a predetermined color corresponding to each of picture elements of a primary color image; an error calculating section for calculating a quantization error between the input and output of the quantization section, to output as a quantization error signal; and a feedback correction section for adding the quantization error signal derived by the error calculating section, to the corresponding color ink amount indicative signal of the surrounding picture element, for correcting the ink amount indicative signal.

Abstract: The present invention discloses a dynamic control of a drive circuit to a diode laser used in a raster output scanning system. In the prior art, the binary serial stream input to a diode laser operates on the laser to pulse the laser on when a "one" input is applied, the laser staying on when the first one input is immediately followed by successive one inputs. The first on pixel creates an exposure at an image plane which is less than uniform due to the characteristics of the drive circuit due to the overshoot or undershoot characteristics of the drive circuit. The second and succeeding pixels following the first pixel turned on will be at a maximum exposure value and hence will have an undesirable exposure contrast with the first pixel.

Abstract: An electrophotographic image recording apparatus that forms an electrostatic latent image so that the uniformly charged surface of a photoreceptor is scanned for its exposure with a beam spot of a light beam generated according to image information, to discharge the surface of the photoreceptor up to a medium potential. The electrophotographic image recording apparatus includes a light beam generator capable of varying an amount of light beam and a light intensity distribution pattern of a beam spot on the surface of the photoreceptor, an intensity distribution pattern controller for controlling the light beam generator according to the image information of peripheral pixels, to vary the intensity distribution pattern of the beam spot on the surface of the photoreceptor, and a light beam output controller for controlling the light beam generator to put the exposure energy on pixels, exposed to the beam spots of intensity distribution patterns, at a predetermined value.

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: A technique for screening an image for half-tone reproduction by image reproduction apparatus including a marking device which is operative to mark a medium along a multiplicity of parallel marking lines including the steps of providing a digital representation of density values of an original image, storing dot shape information representative of a screen function in a line-by-line, input density-by-input density arrangement and extracting the dot shape information from storage for the density values in the form of information that designates on and off points for each marking line. Apparatus for carrying out the technique is also disclosed.

Abstract: An imaging system and method employ a linear perceived optical density interface that produces a substantially linear relationship between digital image values generated by an input imaging device and perceived optical densities of corresponding pixels within a visible representation of the image on film. The interface produces a linear change in perceived optical density in response to a linear change in the digital image values, enabling a system user to achieve predictable changes in appearance characteristics by simply adjusting the digital image values. The user can adjust the appearance characteristics in a flexible manner, without being constrained to a set of fixed transfer functions. The user can also perform desired formatting of the image at the input imaging device. The interface provides a single transfer function that is commonly applicable different input imaging devices, such that development of modality-specific transfer functions is unnecessary.

Abstract: An image forming apparatus with a solid-state scanning optical print head reproduces tones by an intensity modulation method, corrects light dispersion of each element by a pulse modulation method, and corrects fluctuations in sensitivity characteristics of a photosensitive member by switching the drive current value of maximum light exposure.

Abstract: A thermal recording device scans a laser beam over a thermosensitive recording medium which comprises a support coated with a coloring agent, a color developer, and a light absorbing dye and produces a color having a density commensurate with the lever of a thermal energy applied thereto, thereby to record an image thereon. The thermal recording device has a laser beam applying mechanism for emitting and applying a laser beam modulated by an image to be recorded to the thermosensitive recording medium, a temperature or humidity detecting mechanism for detecting a temperature or humidity with respect to the thermosensitive recording medium, and a controller for correcting the intensity of the laser beam emitted by the laser beam applying mechanism based on the humidity detected by the humidity detecting mechanism.

Abstract: An image processing system for performing thresholding. The system includes a source of image data, where the source of image data provides an image value and associated two dimensional slope information for that image value. And, the system includes thresholding circuitry utilizing the image value and the two dimensional slope information for determining a thresholded value from the thresholding circuitry.

Abstract: A system for writing geometric structures on a photosensitive substrate including a modulated laser beam source, a focusing lens, a deflector for producing a scanning action between the light source and the lens, and a device for mechanically moving the surface relative to the laser beam. Compressed data for use in writing the geometric structures is read out of a memory into a data delivery circuit such that the data is formatted to have both beam power and position information. A modulator logic circuit operates to call up the data from the data delivery circuit, form a modulation drive signal based on the power information, and delay the modulation drive signal based the position data. The modulator logic circuit thus operates to vary the modulation drive signal to begin or end exposure along the scan lines with greater resolution or pixel density by at least a factor of four more than the resolution or spacing density between adjacent scan lines.

Abstract: In a digital image forming apparatus, the intensity or the pulse width of laser beam exposure is modulated according to image signals of a document detected by a sensor. A peak waveform having a peak is generated in each light-emitting period of laser beam. For example, and a signal having a peak is synthesized with the image signals to generate the peak waveform. Thus, the laser is driven according to the peak waveforms so that the exposed portions on a photoconductor in correspondence to the peaks are exposed with a larger quantity of light at low densities. Then, the amount of the gamma correction can be decreased and the gradation characteristic can be stabilized.

Abstract: Image data input from a host computer is converted into data BDATA corresponding to a beam diameter at an image control circuit. BDATA is input into a voice coil 21 driving a collimator lens through a collimator lens driving circuit 3, and the diameter of a laser beam is thus determined. Meanwhile, BDATA is input to a laser beam driving circuit 2 together with a signal LDATA controlling light emission from a laser diode. The laser diode is driven at an intensity corresponding to the beam diameter based on BDATA and LDATA at laser driving circuit 2. An optical apparatus capable of reproducing an accurate dot diameter according to a beam diameter is provided as a result.

Abstract: The improved color image forming apparatus is adapted for image formation from either a reflection-type original or a transmission-type original by the user who selects the proper exposure optics (or unit) in accordance with the kind and size of the original to be duplicated. The apparatus is capable of image formation with the necessary color and/or density related adjustments being performed by basically the same operating device through basically the same operation without any regard to the kind and size of the original and the desired image of high quality can be formed by a simple method. The color and/or density related adjustment necessary for image formation with the selected exposure optics (or unit) is performed by the same input device without regard to the kind of document to be duplicated.

Abstract: A laser beam of a constant intensity is generated by a semiconductor laser and applied to a thermosensitive recording medium. The density of a colored recorded area of the thermosensitive recording medium is detected by a densitometer, and shading correcting data for making the density of the colored recorded area constant based on the detected density are stored in a shading data memory. A controller reads the stored shading correcting data and controls the intensity of the laser beam generated by the semiconductor laser based on the shading correcting data for thereby compensating for variations in the level of an image signal due, for example, to intensity irregularities of the laser beam applied to the thermosensitive recording medium and irregularities of the speed at which the thermosensitive recording medium is scanned with the laser beam.

Abstract: An intensity controlling circuit device can correct variation in intensity of light beams, due to tolerance occurred in each of a plurality of LED-array chips, emitted by LEDs provided in each of the LED-array chips. The intensity controlling circuit device is connected to at least one LED-array chip comprising a plurality of LEDs and slave transistors corresponding to each of the LEDs. The intensity controlling circuit device comprises an intensity controlling circuit connected to the respective LED-array chip. The intensity controlling circuit comprises a first transistor provided between a power source and a constant current generating unit so as to supply a current to the LED-array chip, and an intensity adjusting unit having a second transistor connected to the first transistor in parallel and a controlling unit for controlling the on/off state of the second transistor.

Abstract: A laser scanner control circuit which is used for an apparatus for scanning onto a photo sensitive material by a laser beam and forming an image thereon is constructed as a monolithic driver IC onto a single chip. A reset circuit is provided for a sample-hold circuit so as to minimize the laser power when the image forming apparatus is in a standby mode. A circuit to detect an abnormality of the laser power is further provided. Due to this, the safety of the laser power control of the sample-hold circuit is improved. The operation of the sample-hold circuit can be started at a time point when the laser emitting operation is stable.

Abstract: A pulsed imaging Raster Output Scanner utilizes pulse width modulation in conjunction with asymmetric spatial filtering to prevent overshoot of the intensity and maintain precise intensity levels into the other exposure levels.

Abstract: An image recording apparatus comprises an unequal interval quatization circuit for quantizing at an unequal interval an input multilevel image signal to prevent at least one signal having a tone level at which a recording density is unstable from being outputted, a circuit for calculating a difference between an unequal-interval-quantized signal and the input image signal, a buffer memory for temporarily storing the difference, a multiplexer for multiplying a recorded signal with a weight coefficient, an adder for adding a resultant signal from the multiplier to the input image signal, and a printer for recording an image, using the quantized signal as a record signal.

Abstract: A graduation reproduction method in performing the halftone recording due to screen percentage by a light spot of a light beam with the light beam being intensity-modulated on the basis of digital image data in accordance with a binary recording technique. An illumination time value is reduced with respect to the normal illumination time value determined under a recording condition set to record a minimum recording dot on the recording medium. The reduced illumination time is set as a unit illumination time at the time of the recording of the halftone and the secondary scanning speed is reduced in correspondence with the rate of reduction of the unit illumination time relative to the normal illumination time value. Further, in the case that the recording operation is the screen percentage to be effected by the light spot only for the unit illumination time, the exposure is arranged so as not to be effected by the light spot, or arranged to be effected for the normal illumination time value.

Abstract: A dry-type toner is temporarily put on a printing paper with electrification by an electrifying unit and a toner supplying unit. A laser diode is driven on the basis of a video signal to emit a laser beam by which the dry-type toner put on the printing paper is melted and fixed thereon. A remaining toner that was not melted on the printing paper is eliminated by a cleaning unit. A printing by the laser beam can be realized most easily without using expensive parts such as a photosensitive material or the like and without increasing its mechanism and circuit scale.

Abstract: A raster output scanning system is disclosed which utilizes two light beams to double scan two scan lines on a photoreceptor in order to generate three exposure levels required for a tri-level printing system. In the raster output scanner of this invention, the two light beams scan two separate scan lines. At the completion of the simultaneous scanning of two light beams when the first light beam starts to scan a new scan line, the second light beam start to scan the scan line that the first light beam just completed scanning. In this invention the first light beam generates two exposure levels and the second light beam adds additional exposure to the second exposure level in order to generate a third exposure level. The same method can be utilized to generate additional levels for printing systems with more xerographic levels than three.

Abstract: A method and apparatus for printing stroke and contone data together are provided in which data to be printed (102) is identified by a processor (100) as being either stroke or contone data. For contone data, processor (100) controls a light source (14), a spatial light modulator (12), and an optical photoconductive drum (16) to generate image quality graphics by using spatial light modulation in the process and cross-process directions. For stroke data, processor (100) controls light source (14), spatial light modulator (12), and optical photoconductive drum (16) for high resolution printing by using intensity modulation. Processor (100) is operable to control light intensities through the use of lookup tables stored in a memory (104).

Abstract: In an electrophotographic image forming apparatus including a charger for electrically charging the photoconductor to a predetermined initial electric potential, a laser projects a light onto the photoconductor so as to form an electrostatic latent image thereon, and a developing device develops the latent image with toner so as to form a toner image thereon. Further, a charger controller controls the charger based on a detection result of a detector for detecting a state of the photoconductor so that the initial electric potential of the photoconductor changes in a predetermined range, and a selection controller selects one of the plurality of gradation correction data stored in a storage unit based on the detection result of the detector when the initial electric potential of the photoconductor is an upper or lower limit value of the predetermined range.