Abstract: An image forming apparatus includes a first image forming station for forming, on the basis of an input signal indicative of an image, a toner image on a recording material with such a toner of toners having the same hue and different lightness as has a predetermined color and a low lightness; a second image forming station for forming, on the basis of an input signal indicative of an image, a toner image on the recording material with such a toner of the toners having the same hue and different lightness as has the predetermined color and a high lightness; changing means for changing a toner amount per unit area in each of the first image forming station and the second image forming station in accordance with a density level indicated by the image input signal for the predetermined color so that in a low density range, the toner amount per unit area is larger in the second image forming station than in the first image forming station; a first residual toner container for accommodating toner removed by first

Abstract: A toner patch sensor for use in an image forming device may be operated in different modes according to the color of the patch being sensed. The toner patch sensor may include a detector and a source adapted to transmit light that is reflected off a toner patch and towards the detector. The detected light may be specular and/or diffuse. A controller may selectively change the amount of one or both of the specular and diffuse light received by the detector. The source may include separate emitters for the specular and diffuse light, with the controller selectably turning off one of the emitters or selectably adjusting a ratio of illumination power between the emitters. Alternatively, the source may include a single emitter and an optical element to split light between specular light and diffuse light. Diffuse light may be blocked when sensing black toner patches.

Abstract: In an image forming apparatus provided with an image forming portion for forming a toner image on a rotatable image bearing member, and a detecting portion for detecting a toner image for detection formed on the image bearing member, wherein the state of the image forming portion is controlled on the basis of the result of detection of the toner image by the detecting portion, and the result of detection of the surface of the image bearing member on which the toner image is not formed by the detecting portion, the detection of the surface of the image bearing member on which the toner image is not formed by the detecting portion is effected at each substantially 1/n cycle (n being 2 or greater integer) in one revolution of the image bearing member.

Abstract: A toner density detection apparatus has a sensor unit and a controller. The sensor unit irradiates a toner patch formed on an image carrier with light, splits the light reflected by the toner patch into first and second light components, receives the first and second light components, and outputs first and second light reception signals. The controller causes an analog/digital converter to convert, based on a reference voltage, the output first and second light reception signals into first and second digital data, and detects the density of the toner patch based on the first and second digital data. The toner density detection apparatus adjusts the toner density detection value based on a comparison between a first reference value stored in advance and the first digital data, and a comparison between a second reference value stored in advance and the second digital data.

Abstract: An image detector has an I/V converter for converting, into a voltage output., a current output as a result of a photoelectric element arranged in a traveling direction of an intermediate transfer belt having received light reflected from the intermediate transfer belt and light reflected from toner images formed on the intermediate transfer belt; a peak-hold unit for holding an output voltage into which the light reflected from the intermediate transfer belt has been converted by the I/V converter; and a computation unit for detecting a difference between the output voltage of the peak-hold unit and an output voltage into which the light reflected from the toner images of respective colors has been converted by the I/V converter.

Abstract: When a regular reflection light receiving unit is receiving a reflected light in a non-image area where the test patches are not formed, a clamp switch is closed. Then, a first reference voltage generated by a pull-up resistor and a zener diode is corresponded to an electric potential of a terminal of a capacitor on the side of an A/D converter. The capacitor is charged by the difference in electric potential between the first reference voltage and an output voltage from the regular reflection light receiving unit. Next, the clamp switch is opened. After the regular reflection light receiving unit receives the reflected light from an image area where the test patches are formed with this state of things, the output voltage from the regular reflection light receiving unit is changed. The difference in density between the image area and the non-image area can be quantified by the A/D converter.

Abstract: A device to measure toner concentration can include a selector that selects a type of developer material to be measured and a sensor that detects an amount of light reflected off a developer material. A controller within the device can determine a value corresponding to a toner concentration of the developer material based on the amount of light detected by the sensor.

Abstract: In an image forming apparatus provided with an image forming portion for forming a toner image on a rotatable image bearing member, and a detecting portion for detecting a toner image for detection formed on the image bearing member, wherein the state of the image forming portion is controlled on the basis of the result of detection of the toner image by the detecting portion, and the result of detection of the surface of the image bearing member on which the toner image is not formed by the detecting portion, the detection of the surface of the image bearing member on which the toner image is not formed by the detecting portion is effected at each substantially 1/n cycle (n being 2 or greater integer) in one revolution of the image bearing member.

Abstract: An image forming apparatus, comprising: an image forming section for forming and outputting a predetermined gradation patch pattern image on transfer paper; a sensor for reading and outputting the gradation patch pattern image; and a control section for correcting reading characteristics of the sensor on the basis of an output value of the sensor obtained by reading the gradation patch pattern image and a color value of the gradation patch pattern image formed on the transfer paper.

Abstract: A polarographic densitometer has a voltage applying circuit, a sensor unit, an impedance reduction circuit, and a current/density conversion unit. The voltage applying circuit applies specified voltage, and the sensor unit includes a group of electrodes to produce a current output in response to any reaction caused in a specimen when the specified voltage is applied by the voltage applying circuit. Furthermore, the impedance reduction circuit reduces impedance of the specimen between the electrodes of the group, and the current/density conversion unit converts the current output of the sensor unit when the impedance is reduced by the impedance reduction circuit into the density of specific material in the specimen.

Abstract: An image forming apparatus forms a toner image on a toner image bearing body and the toner image is transferred onto a recording medium. An image forming section forms the toner image on the toner image bearing body, which may be a transfer belt. A reading section optically reads the toner image formed on the image bearing body. A covering section is provided between the reading section and the toner image bearing body. The covering section can move between an opening position, where the covering section covers the reading section, and a closing position, where the covering section does not cover the reading section. A drive mechanism drives the covering section to move between the opening position and the closing position. An adjustment section adjusts the reading section when the covering section is at the closing position. The covering section includes a reflection member attached thereto.

Abstract: An image sensing device includes: a light source, a recording member on which an image is formed and conveyed in one direction, illumination system for causing a light beam emitted from the light source to obliquely illuminate the recording member and, imaging system for condensing specularly reflected light from the image on the recording member and causing the reflected light to travel to a surface of a photodetector, so that the image sensing device obtains positional information of the image on the recording member on the basis of a signal obtained by the photodetector. When the amount of displacement of the recording member in a vertical direction during conveyance of the recording member is d, an angle between the optical axis of the imaging system and a normal to the recording member is ? (degrees), and resolution of the image formed on the recording member is R (dpi), the components are set so that d·tan ?<(25.4/R)×1000 is satisfied.

Abstract: An image forming apparatus of the present invention includes an image carrier on which a developer is to be deposited by an electrophotographic system. A controller controls the amount of the developer to deposit on the image carrier by varying a potential for development. A reflection type sensor for sensing the amount of the developer deposited on the image carrier is made up of a light source and a light-sensitive device for. An adjusting device adjusts a set value set in the controller for controlling the amount of the developer to a target value. The sensor is of a diffuse reflection system and has a correcting function. The adjusting device causes the sensor to sense the amount of the developer deposited on a test patch, which is formed on the basis of a preselected set value, and then calculates an adjustment value of the set value on the basis of the amount sensed by the sensor and the target value.

Abstract: An image forming apparatus has an image bearing member, and a density detecting device for detecting the density of an image for density detection formed on the image bearing member. Image forming conditions are controlled on the basis of an output from the density detecting device. The density detecting device has a regular reflection type density detecting device for detecting the density by regular reflection light from a portion to be detected, and a diffuse reflection type density detecting device for detecting the density by diffuse reflection light from the portion to be detected. The output value from the diffuse reflection type density detecting device is corrected on the basis of the output value from the regular reflection type density detecting device which has detected a reference image, and the output value from the diffuse reflection type density detecting device which has detected the reference image.

Abstract: A method and apparatus for a single densitometer design that is used for all colors within multiple color image processing system. The preferred embodiment employs an LED having a light adjustment mechanism for controlling the amount of light received by a light detector in the densitometer. The coarse light adjustment is provided through a variable aperture. Fine light adjustment is accomplished through controlling the current through the LED, either by a potentiometer or through an automated process. Preferably, each of the LEDs is selected by wavelength to maximize the absorption by the colorant yielding light roughly complimentary to the colorant. The adjustment circuit provides advantage in color printing systems by allowing duplicate versions of the same densitometer circuit to yield similar voltage outputs for different colorants, thereby compensating for different absorption characteristics and light output of different colored LEDs.

Abstract: An object of the invention is to provide a toner density sensor capable of detecting toner density with high accuracy without being affected by the temperature change. A light-emitting diode emits infrared light toward the toner attached to the surface of a photosensitive drum, and the infrared light reflected from the toner is received by a photodiode. An amplifier circuit for detecting color toner density and an amplifier circuit for detecting black toner density, of which both amplify outputs from the photodiode, each employ a thermister for the feedback resistance of the amplifier. An input resistance in the amplifier circuit and the thermister adjust the gain of the amplifier circuit so as to obtain optimal outputs.

Abstract: A method and apparatus for a single densitometer design that is used for all colors within multiple color image processing system. The preferred embodiment employs an LED having a light adjustment mechanism for controlling the amount of light received by a light detector in the densitometer. The coarse light adjustment is provided through a variable aperture. Fine light adjustment is accomplished through controlling the current through the LED, either by a potentiometer or through an automated process. Preferably, each of the LEDs is selected by wavelength to maximize the absorption by the colorant yielding light roughly complimentary to the colorant. The adjustment circuit provides advantage in color printing systems by allowing duplicate versions of the same densitometer circuit to yield similar voltage outputs for different colorants, thereby compensating for different absorption characteristics and light output of different colored LEDs.

Abstract: A method, apparatus and article of manufacture for modifying printing based upon direct on-the-fly media characteristic parameters is disclosed. The present invention on-the-fly directly measures a media characteristic parameter and performs real-time print modification in response thereto. The measured characteristic parameters include paper texture and composition, as well as adhesion and penetration of print. The modification of print in response to these measured parameters may allow a customer to maintain observed print quality with lower-cost materials. Adjustments may include the addition of coating, hot rolling, or adjustment of toner concentration. Measured parameters may include mottle, paper texture, and bleed through.

Abstract: This invention provides an image-forming machine with a pulse densitometer that avoids the formation of artifacts on electrophotographic films. The image-forming machine may have a charger, an exposure machine, a toning station, a transfer charger, a fusing station, and a densitometer positioned next to a photoconductor. The densitometer may have an emitter, a collector, and a pulse apparatus. The densitometer provides one or more pulses to measure the toner and photoconductor densities. The pulsed emissions are essentially below the exposure threshold of electrophotographic films, especially those sensitive to the infrared spectral region.

Abstract: This invention provides an image-forming machine with a pulse densitometer that avoids the formation of artifacts on electrophotographic films. The image-forming machine may have a charger, an exposure machine, a toning station, a transfer charger, a fusing station, and a densitometer positioned next to a photoconductor. The densitometer may have an emitter, a collector, and a pulse apparatus. The densitometer provides one or more pulses to measure the toner and photoconductor densities. The pulsed emissions are essentially below the exposure threshold of electrophotographic films, especially those sensitive to the infrared spectral region.

Abstract: A toner amount measuring apparatus includes an irradiating unit which divides a flux of laser beams emitted from a laser diode into two fluxes of laser beams by an obtuse-angled prism and makes the two light fluxes interfere with each other to form interference fringes on a photosensitive roll, and a photodetecting unit including an optical sensor for detecting reflection light obtained by reflecting the light constituting the interference fringes from the photosensitive roll.

Abstract: The invention provides a diagnostic system for a densitometer in an image-forming machine. An image-forming machine with a densitometer diagnostic system may have a photoconductor, one or more chargers, an exposure machine, a toning station, and a densitometer. A densitometer diagnostic system for an image-forming machine may have an emitter, a collector, amplifier circuitry, and diagnostic circuitry. The diagnostic circuitry reduces the drive current to the emitter in the densitometer by a known or calculable value. The output voltage from the amplifier circuitry in the densitometer is reduced in proportion to the reduction in the drive current. To perform diagnostic testing of the densitometer, a first output voltage is obtained from the densitometer without the diagnostic circuitry connected. A second output voltage is obtained from the densitometer with the diagnostic circuitry connected.

Abstract: An object of the invention is to provide a toner density sensor capable of detecting toner density with high accuracy without being affected by the temperature change. A light-emitting diode emits infrared light toward the toner attached to the surface of a photosensitive drum, and the infrared light reflected from the toner is received by a photodiode. An amplifier circuit for detecting color toner density and an amplifier circuit for detecting black toner density, of which both amplify outputs from the photodiode, each employ a thermister for the feedback resistance of the amplifier. An input resistance in the amplifier circuit and the thermister adjust the gain of the amplifier circuit so as to obtain optimal outputs.

Abstract: A toner mark transfer unit transfers a halftone pattern such as a transverse line pattern or a slanted line pattern on a belt by using a plurality of electrostatic recording units. A toner density measurement unit figures out density control parameters such as emission time and emission current on the basis of the ratio of a reflected light (inter-line space width) from the toner free portion to a light (line width) attenuated due to a diffuse light from the toner bearing portion in a read signal of a halftone pattern from a sensor unit.

Abstract: An image forming apparatus of the present invention includes an image formation unit for forming a developer image on a photosensitive drum, a transfer belt for conveying a sheet while placing it on a transfer surface and for allowing the developer image formed on the photosensitive drum to be transferred on the sheet or allowing the developer image to be directly transferred on the transfer surface as a mark for control of the image formation, a density sensor provided such that a detecting surface faces the transfer surface of the transfer belt to optically detect the control mark formed on the transfer belt, a control section for controlling the formation of the developer image on the photosensitive drum executed by the image formation unit in accordance with detection information of the density sensor, a shutter plate movably provided between the detecting surface of the density sensor and the transfer surface of the transfer belt to move in a first direction and open the detecting surface of the density

Abstract: The present invention provides an image forming apparatus that has image forming device for forming a toner image, first detecting device for detecting the quantity of regularly reflected light from the toner image, and second detecting device for detecting the quantity of irregularly reflected light from the toner image.

Abstract: A densitometer with built-in data processing capability uses synchronizing signals to collect data at defined spots on a moving endless belt or drum test sample. A calibration cycle accumulates data for later use in measurement correction. After correction, measurement data are output or stored for later output to a host processor or display device. Data averaging, filtering, smoothing, statistical functions, and pattern recognition are also provided by the densitometer circuitry.

Abstract: A method of accurately measuring control film density regions comprising: exposing a photosensitive film to a modulated laser beam at three known laser beam intensities representing maximum, midrange and minimum intensities to form corresponding separate sequential density regions in said film having maximum density Dmax, midrange Dmin and minimum density Dmin, using a densitometer, taking a first set of density readings of said maximum density region of said film, taking a second set of density readings of said midrange density region of said film, and taking a third set of readings of said minimum density region of said film; wherein said density readings are sequentially taken as said film is moved past said densitometer; and as a first try, determining Dmax as the average of a subset of said first set of density readings which are taken in the control portion of said maximum density region; determining Dmin as a preselected value; and determining Dmid=Dmin+a(Dmax−Dmin) where a is a fract

Abstract: An image forming apparatus performs the gamma correction based on an image density on a photosensitive body or an intermediate transfer body. In the image forming apparatus, a test pattern generator unit generates a test image on the photosensitive body or the intermediate transfer body. A first density detector unit is provided in an upstream of a toner transfer section with respect to a rotation direction of the photosensitive body or the intermediate transfer body, and detects an image density on the photosensitive body or the intermediate transfer body. A second density detector unit is provided in a downstream of the toner transfer section with respect to the rotation direction of the photosensitive body or the intermediate transfer body, and detects the image density on the photosensitive body or the intermediate transfer body. A corrector unit corrects image data.

Abstract: An image forming apparatus includes an photoconductive drum, a charger, an exposing device, a developing device and a transferring device. A photo-sensor is disposed around the photoconductive drum. The photo-sensor senses the intensity of the reflected light from the surface of the photoconductive drum and the reflected light from the reference toner image formed on the photoconductive drum. The intensity of the emitted light from photo-sensor is changed corresponding to a continuous lighting time of the photo-sensor. Therefore, the intensity is compensated in response to the continuous lighting time of the photo-sensor. As a result, accurate toner density is detected.

Abstract: A document original simulator including first tone simulation portion having substantially the same reflectance as a white original sheet and a second tone simulation portion having a lower reflectance than the first tone simulation portion. When an image fogging detecting operation is to be performed with the use of the document original simulator, it is checked whether or not the amount of light reflected from the first tone simulation portion when the first tone simulation portion is illuminated with light is smaller than the amount of light reflected from the white original sheet placed on a document original presenting section when the white original sheet is illuminated with light.

Abstract: An image forming apparatus of the present invention includes an exposure portion to form an electrostatic latent image by exposing the surface of an image carrier, a developing device to form a developer image by developing the electrostatic latent image formed on the image carrier with a developer and a detecting device that has a specified detecting area on the image carrier and detects the quality change of an image formed on the detecting area. The image forming apparatus of the present invention further includes a means to decide a minimum examination image forming area that is nearly in accord with the detecting area of the detecting device by forming an examination image for the image change detection on the image carrier by the exposure portion and the developing device, detecting the formed examination image by the detecting means and changing the examination image forming area according to the detection result of the detecting device.

Abstract: The static latent image formed on the photoreceptor which has been charged, by exposing it to light, is developed through four colors of developing units, i.e., yellow, magenta, cyan and black, forming toner images on the photoreceptor. These toner images are transferred to the transfer drum. Before forming the toner images, a device is provided to correct the measurement value of toner density obtained using the light emitter and photosensor into an exact value. Based on the reflected light from a white-coated area formed on the transfer drum, two levels of the intensities of emitted light are determined. The intensity of received light is compared to the standard value so that the output value from the photosensor corresponding to the toner density is made to approximate the standard value.

Abstract: An electrostatographic recording apparatus includes an endless recording member upon which toner images are recorded. A densitometer is provided for measuring density of a toned area on the recording member. The densitometer includes a light emitting and/or light sensitive component that is located in an internal space confined by the endless recording member. The densitometer further includes a slidable support upon which the component is mounted in facing relationship with and proximate to an internal facing portion of the recording member. A stationary mounting structure is attached to a film core upon which the film-like recording member is supported. The slidable support is received within the stationary mounting structure. An electrical circuit is electrically connected to the component and is mounted on a side of the slidable support that is opposite in facing direction to that of the component.

Abstract: An image forming apparatus includes an photoconductive drum, a charger, an exposing device, a developing device and a transferring device. A photo-sensor is disposed around the photoconductive drum. The photo-sensor senses the intensity of the reflected light from the surface of the photoconductive drum and the reflected light from the reference toner image formed on the photoconductive drum. The intensity of the emitted light from photo-sensor is changed corresponding to a continuous lighting time of the photo-sensor. Therefore, the intensity is compensated in response to the continuous lighting time of the photo-sensor. As a result, accurate toner density is detected.

Abstract: An image forming apparatus is provided which is immune to characteristic variations of a photoconductor and a developer material, which can detect the amount of toner adhering to a test toner image accurately, and which can always form a favorable image using an optimal image forming parameter. A predetermined test toner image is formed on the photoconductor using developing devices. The amount of toner adhering to the formed test toner image is detected by an AIDC sensor. A printer control unit determines grid potential Vg of a corona charger and development bias potential Vb of each developing device based on the detected amount of adhering toner. A predetermined image is formed using the determined grid potential and development bias potential.

Abstract: An infrared reflectance densitometer (IRD) sensor which utilizes four blocks each of which generates an element of a given equation and a fifth block which generates an output voltage based on the given equation. The IRD sensor eliminates a problem known as hunting.

Abstract: An image forming apparatus includes a generating section for generating an image signal representing an image of a predetermined density, an image forming section for forming an image on a recording medium on the basis of the image signal generated by the generating section, a measurement section for measuring the density of the image formed on the recording medium, and a control section for determining a condition for image formation on the basis of a measurement result from the measurement section. The control section selects a density of the image signal to be generated from the generating section according to the environment of the image forming section, or to an operation time of the image forming section.

Abstract: An image forming apparatus includes an image bearing member for bearing an electrostatic image, a plurality of developing units for accommodating developers having different colors, a light source for projecting light onto a developed image, and a photosensor for sensing reflected light from the developed image. The apparatus operates in either a first mode for determining the density of the developed image based on the output of the photosensor when light having a predetermined amount is projected from the light source, or in a second mode for determining the density of the developed image based on the amount of light projected from the light source when the output of the photosensor has a predetermined value. Either the first mode or the second mode is selected in accordance with the color of a developer being utilized during the image formation operation.

Abstract: A printer control unit carries out a predetermined calculation based on the amount of adhering toner detected by an AIDC sensor and the surface potential of a photoconductor detected by a V sensor to correct the light emission intensity of a light source to prepare light emission characteristic data for .gamma. correction to obtain an optimal image. A .gamma. correcting unit corrects an image signal output from an image signal processing unit using the calculated light emission characteristic data for .gamma. correction to control the light source to emit light based on the corrected data. More specifically, since the .gamma. correction data is obtained by calculation, optimal .gamma. correction can always be carried out without a memory of a large capacity.

Abstract: An image forming apparatus forms a patch image on a recording medium, irradiates the patch image formed on the recording medium with light, and detects a quantity of light reflected by the patch image and outputs a first detection signal. The apparatus detects a quantity of light emitted by a light emission source and outputs a second detection signal, and amplifies the first detection signal in accordance with a first amplification gain and outputs a first amplified signal. The apparatus amplifies the second detection signal in accordance with a second amplification gain and outputs a second amplified signal, and controls image forming conditions based on the first amplified signal or the second amplified signal. An adjustment mode is executed prior to controlling the image forming conditions, and the first amplification gain is controlled when the patch image is formed with black toner, and the second amplification gain is controlled when the patch image is formed with color toner.

Abstract: An apparatus which detects a mass of marking material developed on a test patch recorded on a photoconductive surface. The apparatus includes a densitometer, a capacitor sensor and a controller. The densitometer is spaced from and adjacent to the photoconductive surface. The capacitor sensor is also positioned adjacent to the photoconductive surface and spaced therefrom. In operation, the densitometer generates a first signal proportional to the specular component of the total reflectivity of the material deposited on the test patch developed on the photoconductive surface. The capacitor sensor generates a second signal proportional to the mass of material developed on the test patch recorded on the surface. In response to these signals, the controller generates a first control signal as a function of the first signal received from the densitometer in response to the mass of material deposited on the test patch being less than a preselected mass.

Abstract: A method and an apparatus for selecting an amount of light to be irradiated for fog detection onto a photoreceptor from a density detecting device out of amounts of light for low density or for high density. A real original is illuminated by a predetermined amount of illuminating light, whereby a toner image corresponding to the real original is formed on the photoreceptor. Light of an amount for low density from the density detecting device is irradiated onto the toner image to acquire a first density data. Thereafter, a pseudo original is illuminated by the predetermined amount of illuminating light, whereby a toner image corresponding to the pseudo original is formed. Light of the amount for low density from the density detecting device is irradiated onto the toner image to acquire a second density data. The difference between the first and the second density data is compared with a predetermined threshold value.

Abstract: A method of automatically positioning a test pattern in the interdocument zone of an imaging surface of a printing machine using a sensor with a given field of view. Once the test pattern has been provided in the interdocument zone of the imaging surface, the timing relationship of the test pattern to a plurality of edges of the sensor field of view is determined. The control then responds to the timing relationships to locate the sensor field of view with respect to the test pattern and determine the time period between creating a test pattern and sensing the test pattern.