Abstract: An apparatus and method for correcting printing characteristics of a full-line printhead, and producing a high-printing quality printhead at high manufacturing yield, a corrected printhead by this apparatus, and a printer employing this printhead are disclosed. According to this method, an image is printed on a printing medium by using double pulses obtained based on fluctuation of resistance of each printing unit of a printhead, and a reference OD value is determined from an OD value histogram of the printed image. A preheating pulse width is selected, based on OD values of n printed images obtained by changing the preheating pulse width n times and the reference OD value, such that an OD value on each printing element is equal or close to the reference OD value. For example, assuming that the reference value is 0.43, a preheating pulse width on printing element No. 3 is 0.875.mu. sec.
Abstract: Disclosed is an optical writing device having an array of a plurality of writing light shutter elements for an image forming purpose. The optical writing device also has at least one first monitoring light shutter element and at least one second monitoring light shutter element. During recording period, the first second monitoring light shutter element is frequently driven, and the second monitoring light shutter element is infrequently driven. After the recording period, the first and second monitoring light shutter elements are driven with varying voltage, and light amounts from the first and second monitoring light shutter elements are sensed by a sensor. Based on the output from the sensor, optimal drive voltage for the next recording period is set.
July 22, 1999
Date of Patent:
September 26, 2000
Minolta Co., Ltd.
Ken Matsubara, Tomohiko Masuda, Yuji Kamoda
Abstract: A latent image of a medical image is recorded on a heat development photosensitive material. Development is carried out on the photosensitive material, on which the latent image has been recorded, and the medical image having multiple gradation levels is thereby obtained. The development is carried out at a heating temperature falling within the range of 120.+-.10.degree. C., at a width-direction temperature accuracy falling within the range of .+-.3.degree. C., and for a development time falling within the range of 5 seconds to 30 seconds. In the heat development technique, the processing time is thus set to be a practically acceptable short time, noise is reduced, and a medical image having good image quality is obtained.
Abstract: A light intensity control apparatus includes an optical beam splitter which splits light into monitor light and principal light; a polarization beam splitter which splits the monitor light into two polarized light components; a monitor light detector which detects the polarized light components; a polarization correction device which corrects the output of the monitor light detector so that the intensity of the output signal of the monitor light detector and the light intensity of the principal light on an object surface have a predetermined correlation, regardless of the polarization state of the light incident upon the optical beam splitter; and a humidity dependency correction device which corrects the output of the monitor light detector via the polarization correction device by detecting a variation in polarization dependency characteristics of the optical beam splitter, caused by a change in humidity, and feeding the variation back to the polarization correction device, so that the output signal intensi
Abstract: An image forming apparatus which writes an electrostatic image onto a photoconductor by laser light. An image writing resolution is set and a controller controls writing laser power according to the set image writing resolution. The controller also controls the writing laser power for a high resolution mode to be greater than the writing laser power for a low resolution mode.
Abstract: After the digital copier has been assembled, a magnification error is calculated. The magnification error is a size ratio of a 100% copied image to an original image. The main CPU of the copier changes the rotational speed of the polygon-mirror driving motor to a new speed, in accordance with the magnification error. Further, the main CPU changes the speed of the main motor for the photosensitive drum in accordance with the new speed of the polygon-mirror driving motor. Therefore, the magnification of any copied image can be minutely adjusted by changing the rotational speed of the polygon-mirror and photosensitive dram.
Abstract: Driving electric current values of a semiconductor laser when detected light amount values are equal to each of five light amount values having respectively different magnitudes are detected. Thus, five detecting points relating to a light amount value-driving electric current value characteristic are obtained. A differential efficiency .eta. at an interval between two adjacent detecting points is calculated. For example, a differential efficiency .eta.1 is calculated from an adjacent detecting point and a differential efficiency .eta.2 is calculated from another adjacent detecting point. Further, values of the differential efficiencies are displayed on a display so that an operator can recognize an exact deteriorated state of an LD from the values of the differential efficiencies.
Abstract: A multi-beam scanning system has a beam control using an Electrostatic Voltage Sensor or an Image Density Sensor on the Organic Photoconductor. The laser beams can be attuned according to the voltage or density results. This results in a more reliable system as compared to the use of one or more photodetectors.
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 electrophotographic printer includes a photosensitive drum, charging roller, image writing device, developing roller, and controller. The controller controls the operations of the image writing device and the developing roller so that a difference in potential between the surface of the photosensitive drum and the developing roller is below a firing potential. The controller causes the image writing device to fully emit light for a first predetermined time period immediately before completion of a printing operation, and for a second predetermined time period immediately after the printing operation starts, thereby bringing the surface of the drum to a potential nearly zero volts. The photosensitive drum stops rotating after the first predetermined time period and the photosensitive drum starts rotating immediately before the first predetermined time period. The photosensitive drum does not necessarily stop at exactly the same angular position after each printing operation.
Abstract: An adjusting apparatus and method for adjusting a recording device such as a color laser printer or copier. The recording device has a light emitting device, an electrical resistance device, and a controlling device. The controlling device controls the emission period of the light emitting device according to the resistance of the electrical resistance device. The adjusting apparatus has a controller that controls the light emitting device of the recording device to be in a predetermined active state. The adjusting apparatus also has an adjusting device that adjusts the resistance of the electrical resistance device in accordance with the light emission intensity of the light emitting device. A recording device that is readily adjusted by such an adjusting apparatus is also disclosed.
Abstract: The present invention relates to a laser diode driving circuit for supplying a drive current to a laser diode, a semiconductor integrated circuit for driving the laser diode, and an image recording apparatus in which a step of executing a scanning on a predetermined member to be scanned with a laser beam holding image information is included in an image recording step. The laser diode is certainly kept in a no light emitting state at a timing when the laser diode should be kept in the no light emitting state and is allowed to emit a laser beam of the light quantity faithfully corresponding to the drive current at a timing when the drive current is supplied to the laser diode. A bias current out of the bias current and a drive current which are supplied to a laser diode 1 is further divided into a first bias current and a second bias current. Normally, only the first bias current is supplied to the laser diode. The second bias current is supplied and stopped in a manner similar to the drive current.
Abstract: A light intensity controlling device has a beam splitter which splits light fluxes emitted from a plurality of independently controlled semiconductor lasers, guided by optical fibers, into monitor light fluxes and main light fluxes. A gain adjusting circuit corrects the changes of output of light receiving elements depending on the polarization states of the light fluxes incident into the beam splitter. The changes result from the polarization characteristics of the optical fibers and/or the beam splitter. Alternatively, a filter is provided at one of the light receiving elements to compensate for the changes, thus providing a corrected output signal. Laser control circuits control the light emitting intensity of each semiconductor laser based on corrected output signals. The light receiving elements are set at an angle to the incoming light as so to avoid directing reflected light back toward an imaging system or the lasers.
Abstract: The invention is directed to a method of calibrating a laser in an electrophotographic image forming apparatus used for producing a print image on a print medium. A laser having a selectively energizable laser beam output is provided. A rotatable optical device and the laser combine to define a movable projection path of the laser beam output. Rotation of the optical device results in movement of the projection path across a scan line overlaying a photoconductive drum. The optical device has a rotational acceleration upon initial rotation thereof with a ramp-up period during which the rotational velocity increases. A safe area is established in a portion of the scan line which does not overlay an image area on the photoconductive drum. The laser is energized and calibrated when the projection path is positioned in the safe area. The calibration is carried out during the ramp-up period of the rotating optical device.
March 20, 1997
Date of Patent:
January 26, 1999
Lexmark International, Inc.
Craig Palmer Bush, Cyrus Bradford Clarke, David Brian Langer, Phillip Byron Wright
Abstract: An image forming apparatus which automatically adjusts an image density when at least one of conditions of an optical writing operation, including a size of a dot image, a light strength of a laser beam, a mode of image resolution, and a scanning speed of the laser beam, is changed. When an instruction by an operator for changing the conditions of the optical writing operation is input, an optical writing controller executes a change of the conditions and a process controller then executes an operation of determining a development potential and associated bias potentials on the basis of the changed conditions of the optical writing operation. In the operation of determining a development potential and associated bias potentials, a predetermined reference dot image is written on a photoconductor by a laser beam under the changed condition of the optical writing operation and is developed with color toner under the determined development potential and associated bias potentials.
Abstract: Information is recorded on a heat-sensitive recording material including a photo-thermo conversion agent which converts supplied light energy into heat energy, a developing agent and a color forming agent which is encapsuled in micro-capsules whose permeability to materials increases with increase in said heat energy and forms a color by reaction with the developing agent. The photo-thermo conversion agent is localized in and/or on the micro-capsules. The heat-sensitive recording material is heated by supplying the heat-sensitive recording material with heat energy less than energy necessary to cause the heat-sensitive recording material to form a color. A light beam modulated according to the information to be recorded is caused to scan the recording material.
Abstract: When a control part is restarted, an average of a stored standard operation quantity and a stored operation quantity immediately before a stop of the control part is calculated. The average operation quantity (for instance, laser power) is applied to an image output part, and a resulting control quantity (for instance, a development density) is measured. A control rule retrieval unit calculates adaptabilities of respective control rules with respect to the measured control quantity, thereby synthesizing an application control rule. A new operation quantity is determined based on the application control rule and an error of the measured control quantity from a target value.
Abstract: A thermal recording device records information on a heat-sensitive recording material which develops color in a density according to heat energy supplied thereto. The thermal recording device pre-heats the heat-sensitive recording material with heat energy less than energy necessary to develop color in the heat-sensitive recording material and scans the recording material with a laser beam modulated according to the information to be recorded. A region from the upper surface of the heat-sensitive recording material to a space above the upper surface of the heat-sensitive recording material through which the laser beam impinges upon the heat-sensitive recording material is isolated from the surrounding space at least at its sides and top by side isolating members and a top isolating member, and at least the top isolating member is transparent so that the laser beam impinges upon the heat-sensitive recording material through the top isolating member.
Abstract: A potential estimation apparatus estimates a potential of a photosensitive body of an image forming apparatus that carries out an electro-photography process using the photosensitive body. The potential estimation apparatus includes a sensor group for sensing and outputting data related to information which affects the electro-photography process, a storage unit for at least storing the data output from the sensor group and information related to charge of the photosensitive body, and an estimation circuit including a neural network for estimating a charged portion potential of the photosensitive body based on a charge retentivity of the photosensitive body learned by the neural network.
Abstract: Binary data (VDO) developed to a dot pattern are sequentially stored in line memories (1-9). A processing circuit (43) is constituted by a logic calculation circuit, and determines an edge portion of an image or a halftone image on the basis of 11.times.9 pixel data in shift registers (34-43). When the edge portion of an image is determined, data of a pixel of interest is converted to data that can print a smooth edge portion. Changed data (VDOM) is converted again according to the type of toner. The converted signal is supplied to a laser driver of a printer, and a printing operation is performed by scanning a laser. A resolution setting unit (1700) receives a resolution setting command from an external apparatus (1300), and sets a designated resolution in a printer (1200) according to the resolution setting command.
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: A method of achieving optimum optical contrast for detecting registration marks in a multicolor electrophotographic printing machine. The reflectivity of the image carrying member which is usually an intermediate transfer belt is determined. The reflectivity of each of the toners is then determined. If one of the toners has a contrasting reflectivity, while the remaining toners do not contrast then a uniform field of the contrasting toner is imaged and developed and the registration marks for the other toner colors are then developed on top of the uniform field. A void in the field in the shape of the other toner marks is used as the registration mark for the contrasting toner. If all of the toners have a contrasting reflectivity with the belt, the registration marks are imaged and developed directly on the belt.
Abstract: An image processing apparatus for processing gradation images which includes a pattern forming circuit for forming a predetermined pattern on a medium. A detecting device detects the predetermined pattern on the medium and generates a detection signal. A processing circuit processes the input image signal in accordance with the detection signal and outputs a reproduction signal. A setting device manually sets an image signal processing condition of the processing circuit, thereby accomplishing optimization of the image processing.
Abstract: An image forming device suitable for use in a laser beam printer includes an image forming unit for forming an image on a photoconductor, and a reproduction unit for reproducing a high density image and a halftone image on the photoconductor. A detector then detects the density of the high density image and the halftone image formed on the photoconductor. A controller controls an image forming condition of the image forming unit based on a detection result by the detector.
Abstract: A method of and an apparatus for thermally recording an image on a thermo-sensitive recording medium. The apparatus comprises a heating mechanism for applying the thermo-sensitive recording medium with a coloring thermal energy to record the image, a conveying mechanism for moving the recording medium in a sub-scanning direction, a moisture content adjusting mechanism for adjusting the moisture content of the recording medium unexposed to the thermal energy, a humidity detecting mechanism for detecting the humidity in the vicinity of the position where the recording medium is exposed to the thermal energy, and a controller for controlling the moisture content adjusting mechanism based on the detected humidity.
Abstract: A thermal recording apparatus includes a laser beam generator for emitting a laser beam to record an image or the like on a thermosensitive recording medium, a preheating device for preheating the thermosensitive recording medium to a temperature lower than a coloring temperature thereof, an auxiliary scanning feeder for feeding the thermosensitive recording medium in an auxiliary scanning direction, and a controller for establishing a scanning interval employed when the image is to be recorded on the thermosensitive recording medium, depending on an amount of thermal deformation by which the thermosensitive recording medium is deformed when heated to the temperature lower than the coloring temperature. The thermal recording apparatus can record an image of desired dimensions on the thermosensitive recording medium without being adversely affected by shrinkage or expansion caused when the thermosensitive recording medium is heated before or after the image is recorded thereon.
Abstract: The optical energy per pulse emitted by a laser source is accurately controlled from pulse to pulse by controlling the duration of the pulse according to the integrated value of its amplitude over time. A control signal is formed by converting a portion of the optical output of the laser to an electrical signal with a photodetecting element whose electrical output signal is integrated over time. The laser excitation is terminated when the integrated photocurrent reaches a set threshold level representing the optical energy desired for the pulse. Accurate control of the optical energy in each pulse is maintained in spite of error producing conditions such as unpredictable fluctuations in the laser drive signal, ambient temperature fluctuations, transient heating, and cumulative effects due to sequences of pulses.
Abstract: An image forming apparatus including an electrophotographic photosensitive member; a latent image forming device for forming an electrostatic latent image by charging the photosensitive member and exposing it to light information; a controller for controlling the latent image forming means to control tone reproducibility of the electrostatic latent image; an image forming device for forming an image having light, halftone and dark portions, for tone controls, a detector for detecting a state of the tone control image, and wherein the controller controls the electrostatic latent image forming device on the basis of a datum from the detector and predetermined tone correcting information.
Abstract: A controls system architecture for an image output terminal (IOT) has a hierarchical structure which isolates subsystem controls for purposes of efficient algorithm design, analysis and implementation. The architecture is preferably divided into three levels and has a controls supervisor which provides subsystem isolation functions and reliability assurance functions. The architecture improves image quality of IOT outputs by controlling the operation of the IOT to ensure that a toner reproduction curve of an output image matches a tone reproduction curve of an input image, despite several uncontrollable variables which change the tone reproduction curve of the output image.
February 24, 1993
Date of Patent:
November 28, 1995
Tracy E. Thieret, Thomas A. Henderson, Michael A. Butler
Abstract: In a laser beam printer, automatic optical quantity (APC) control is performed based on an optical quantity detection output to generate a laser beam having a predetermined quantity of light. In each scanning cycle, APC is effected by utilizing a period (unblanking period) in which the laser device is forcibly actuated to generate a horizontal synchronization signal. The unblanking period may be changed according to the print paper size or image formation/non-image-formation periods. Also, light quantity control may be effected through a plurality of scanning cycles before image formation and may be effected by utilizing the unblanking period during the period corresponding to the intervals of print sheets. Techniques also provided to prevent a transfer unit from being contaminated by toner images formed as a byproduct of APC.
Abstract: An optical recording apparatus comprises a laser diode array including a plurality of laser diodes for producing a plurality of laser beams in response to a drive signal indicative of an image, an optical system for scanning the laser beams on a surface of a photosensitive body, a beam splitting unit for splitting the laser beams produced by the laser diodes to form control laser beams; a driver for driving each of the laser diodes in the laser diode array, an optical detection unit provided for detecting the control laser beams, the optical detection unit including a plurality of photodetectors in correspondence to the laser diodes in the laser diode array in a one-to-one relationship, each of the photodetectors producing an output signal indicative of an optical power of the control laser beam incident thereto, and a control unit supplied with the output signals from the photodetectors in the optical detection unit for controlling the driver such that each of the laser diodes in the laser diode array produc