Abstract: An image forming apparatus forms a plurality of tone patterns of different colors, each of which containing a plurality of toner patches having different toner densities. Some of the toner patches in each of the tone patterns are formed with a predetermined fixed developing bias and the rest of the toner patches in each of the tone patterns are formed with developing biases set based on previous developing biases that have been obtained through a previous control process. The largest toner density of the toner patches in each of the tone patterns is determined based on a magnitude relation of previous index values obtained through the previous control process.

Abstract: In a reuse method for reusing a reusable device and a sensor of a first image forming apparatus having a first process linear velocity in a second image forming apparatus having at least one second process linear velocity different from the first process linear velocity, the reusable device and the sensor are installed in the first image forming apparatus, and when the first image forming apparatus switches from the first process linear velocity to the second process linear velocity at an initial state before the reusable device is used, output of the sensor at the second process linear velocity is measured. When information on the output of the sensor at the second process linear velocity is stored, the reusable device and the sensor are removed from the first image forming apparatus and installed in the second image forming apparatus.

Abstract: In an image forming apparatus, a toner image formed on a photosensitive drum is primarily transferred onto an intermediate transfer belt. The toner image on the intermediate transfer belt is secondarily transferred onto a transfer material by a secondary transfer roller in contact with the intermediate transfer belt. A relation A>B>C is satisfied, where A is a width of the intermediate transfer member, B is a width of the secondary transfer member, and C is a width of the transfer material. The intermediate transfer member includes a patch-pattern forming area that is not contacted by the secondary transfer member. The image forming apparatus includes a reflection-type photosensor that detects a patch pattern formed in the patch-pattern forming area.

Abstract: An image forming apparatus includes multiple image forming units to form different single-color images with respective different color developers and a control system to selectively perform a multicolor image forming operation, a specific-color image forming operation, a multicolor image quality correction operation, and a specific-color image quality correction operation.

Abstract: An image forming apparatus includes a charge unit, an exposure unit, an exposure voltage detector, a development unit, and a concentration detector. The exposure voltage detector detects a potential of latent image formed as a test pattern on an image carrier. The concentration detector detects concentration of developed test pattern. The image forming apparatus further includes an exposure power controller, an exposure ratio controller, a charging voltage controller, a development bias voltage controller, and an image forming condition adjustment controller. A suitable image forming condition is computed using test patterns formed by changing combinations of charging voltage, exposure power, and exposure duty. The charging voltage is changed in two levels or more. The exposure power is changed in three levels or more. The exposure duty per unit area is changed in two levels or more.

Abstract: An image forming apparatus includes a control device that calculates a developing ability of the developing device based on a detection value detected by an optical detection device from the plural toner patches. The control device adjusts an image formation condition based on the calculated developing ability. A factor detection device is provided to detect a contributing factor that causes the developing ability to largely change after the last adjustment of the image formation condition. The control device controls image formation such that when the factor detection device does not detect the contribution factor and a developing ability calculated this time is different from that calculated last time (as to a part of the plural toner patches), the plural toner patches are formed based on a prescribed fixed image formation condition so that an attraction amount of toner attracting to the plural toner patches enter a prescribed range detectable for the optical detection device.

Abstract: A process cartridge for use in an image forming apparatus includes an image bearing member and a developing unit. The developing unit includes a developer bearing member to bear developer including toner and carrier, a casing forming a developer container containing the developer, a screw having a shaft with a spiral screw blade, a toner density sensor to detect a density of the toner on a detection surface, and a detection surface agitating member fixedly mounted on the shaft of the screw at a position facing a detection surface to scrape away the developer accumulated on the detection surface as the screw rotates. The detection surface agitating member includes an elastic sheet elastically deformable to scrape away the developer accumulated on the detection surface and disposed at a substantially same angle to an axial direction of the shaft of the screw as the spiral screw blade.

Abstract: An amount of toner transfer on a reference pattern is calculated by using an optical detecting unit that detects both regular reflection light and diffuse reflection light from a detection target simultaneously, based on a relative ratio between a value obtained by subtracting a result of multiplying a “diffuse reflection output” by a “minimum value of a ratio between a regular reflection output and the diffuse reflection output” from the “regular reflection output” of the density detection reference pattern, and a value obtained by subtracting a result of multiplying the “diffuse reflection output” by a “minimum value of a ratio between the regular reflection output and the diffuse reflection output” from the “regular reflection output” in the background of a transfer belt or an intermediate transfer body.

Abstract: An image forming method and apparatus capable of implementing accurately and constantly an improved conversion of the amount of toner adhesion over the entire range of the amount of adhesion.

Abstract: An image forming apparatus includes at least one image bearing member, an intermediate transfer member, a secondary transfer member, and at least one optical sensor. In the image forming apparatus, it is determined that output values of the respective amounts of toner detected by the at least one optical sensor are affected by an impact caused due to a separation of the secondary transfer member from the intermediate transfer member and the output values are ignored as image adjustment input information, when the secondary transfer member separates from the intermediate transfer member during any of writing, developing, and transferring the plurality of image adjustment patterns, if the output values fall outside a given range and an interval between the output values of adjacent image bearing members is substantially equal to a distance between the two adjacent image bearing members for the primary transfer.

Abstract: An amount of toner transfer on a reference pattern is calculated by using an optical detecting unit that detects both regular reflection light and diffuse reflection light from a detection target simultaneously, based on a relative ratio between a value obtained by subtracting a result of multiplying a “diffuse reflection output” by a “minimum value of a ratio between a regular reflection output and the diffuse reflection output” from the “regular reflection output” of the density detection reference pattern, and a value obtained by subtracting a result of multiplying the “diffuse reflection output” by a “minimum value of a ratio between the regular reflection output and the diffuse reflection output” from the “regular reflection output” in the background of a transfer belt or an intermediate transfer body.

Abstract: An image forming apparatus and an image density control method for controlling image density in the image forming apparatus, involving adjusting a toner concentration control reference value in accordance with an amount of the toner replaced in a developing device so as to adjust the image density to maintain a consistent developability and changing image forming intervals in accordance with an amount of the toner replaced in the developing device during continuous printing operation.

Abstract: An amount of toner transfer on a reference pattern is calculated by using an optical detecting unit that detects both regular reflection light and diffuse reflection light from a detection target simultaneously, based on a relative ratio between a value obtained by subtracting a result of multiplying a “diffuse reflection output” by a “minimum value of a ratio between a regular reflection output and the diffuse reflection output” from the “regular reflection output” of the density detection reference pattern, and a value obtained by subtracting a result of multiplying the “diffuse reflection output” by a “minimum value of a ratio between the regular reflection output and the diffuse reflection output” from the “regular reflection output” in the background of a transfer belt or an intermediate transfer body.

Abstract: In a color misalignment detection method, an alignment pattern is obtained by designating a plurality of lines having line width and line intervals formed by superposing a line image of a black color as a reference color and a line image of a color other than the reference color, for example, a cyan line image, as one patch, and continuously forming these patches by shifting the relative position between the line images of the two colors by an optional quantity. An alignment pattern detection sensor has a light emitting diode and a photodiode. These elements are arranged along the scanning direction of the alignment pattern such that the photodiode can only receive diffused reflected light of reflected light from the alignment pattern. A spot shape of the light emitting diode and a spot shape of the photodiode are both formed in a square shape.

Abstract: The image forming apparatus includes a developing device that holds a two-component developer to develop an image, a detecting unit that outputs a reference output value and a second output value when the two-component developer is stirred and carried at a stirring/carrying speed corresponding to a second image forming mode, a stirring/carrying member that stirs and carries the two-component developer, and a controlling unit that controls the toner concentration based on the reference output value when forming an image in a first image forming mode, and controls the toner concentration, when forming an image in the second image forming mode, a corrected output value obtained by correcting an output value in the second image forming mode with a difference value between the reference output value and the second output value.

Abstract: An image forming apparatus including an image bearing member, a charging member, and a measuring member. The image forming member is configured to bear an image. The charging member is configured to charge a surface of the image bearing member when a direct current bias voltage is added to at least an alternating bias voltage which is applied to the charging member, and has a frequency fc of the alternating bias voltage. The measuring member is configured to measure a potential of the surface of the image bearing member, and has a drive frequency fvsen. The relationship of the frequency fc and the drive frequency fvsen is expressed as fc?fvsen×n and fc×n?fvsen.

Abstract: A misalignment correction method for forming a plurality of color images on a transfer belt to form a multi-color image and correcting a misalignment of each color using a detection sensor, including forming a patch by superposing a reference pattern as a last color to be superposed on a color pattern to be corrected, preparing a plurality of patches, arranging the plurality of patches on the transfer belt, optically detecting a value of each of the patches with respect to the shift quantity of the respective patches of the continuously formed patch group in the correction pattern, calculating an intersection point of two approximate lines as output obtained on opposite sides of an inflection point of the two lines, and performing misalignment correction based on the intersection point.

Abstract: An image forming apparatus includes an alignment pattern and an alignment pattern detector that detects the alignment pattern. The alignment pattern is formed in such a manner that a line image of a reference color and a line image of a color other than the reference color are superposed on each other with a predetermined shift amount. An acceptance width of the alignment pattern detector is determined so that the acceptance width satisfies a relation with a writing density of the image forming apparatus and a line width of the alignment pattern, as follows: [acceptance width]>[line width]/(5.0627×[writing density(dpi)]?0.5331).

Abstract: An image forming apparatus includes an image forming unit configured to form a plurality of toner images on an image carrier, an optical detector configured to detect reflection light from the toner image, and dedicated to detect infrared rays and near-infrared rays, and a controller configured to perform a predetermined control using a detection results of the optical detector. Gradation pattern that is comprised of a plurality of toner patches formed in the image forming unit with an image forming condition to have different adhesive amounts, and is formed of at least two colors, and detection values detected by the optical detector are used for the predetermined control.

Abstract: An image forming apparatus includes an image carrier configured to carry an electrostatic latent image, a developing device configured to develop the electrostatic latent image with a two-component developer including toner and magnetic carrier, a toner supplier configured to supply the toner to the developing device, a toner concentration detector configured to detect toner concentration in the two-component developer inside the developing device, and a controller. The controller is configured to detect first information to determine toner replacement amount in the developing device during a predetermined time period and second information to determine a charge characteristic of the toner in the developing device, change a toner concentration control reference value based on the first information and the second information, and control the toner concentration based on an output from the toner concentration detector and the toner concentration control reference value.