Abstract: An image forming apparatus includes an adjustment unit that adjusts an image transfer position of the sheet of paper along a main scanning direction that is orthogonal to a transporting direction of the sheet of paper, a fixing unit that fixes on the sheet of paper an toner image using fixing rollers and performs a fluctuation of the fixing roller to the main scanning direction, a detection unit that detects whether or not the fixing rollers of the fixing unit nip the sheet of paper, and a controller. The controller controls the fixing unit to perform the fluctuation of the fixing rollers when determining that the fixing rollers of the fixing unit do not nip the sheet of paper based on a detection result of the detection unit.

Abstract: An image forming apparatus includes a plurality of heaters 56 for heating the fixing roller 52, a plurality of temperature sensors 57 for detecting the temperatures of the areas to be heated by the plurality of heaters 56 respectively, and a control unit 11 for turning on and off the plurality of heaters 56 on the basis of the temperatures detected by the plurality of temperature sensors 57. If one of the heaters 56 is on when the area to be heated by the other heater cools down to the ON temperature, the control unit 11 turns on the other heater with the same timing as the one heater is turned off.

Abstract: An image forming apparatus which allows a user to freely select a desired image quality is provided. The control unit 60 sets a of registration set value A1 for determining a color registration error suppression level and a dropout set value. A2 for determining a dropout occurrence suppression level. Also, the control unit 60 sets a differential circumferential speed which is the difference between the circumferential speed of photoreceptor drums 1Y to 1K and the circumferential speed of an intermediate transfer belt 6 on the basis of the color registration set value A1 and the dropout set value A1. Then, the control unit 60 controls the belt drive motor 1 and the drum drive motor 62 on the basis of the differential circumferential speed which is set.

Abstract: Provided are an image forming apparatus, a fixing device, and an image forming system using the same, including: an image forming section for transferring a toner image onto a recording sheet; a first and second fixing rollers for thermally fixing the toner image on the recording sheet; a first and second temperature sensors each provided at a plurality of positions in a longitudinal direction of the fixing roller; and a rocking section for reciprocally shifting at least one of the fixing rollers in the longitudinal direction of the fixing roller, wherein the temperature gradient of each of the fixing rollers is detected, a central position of reciprocal shift of one fixing roller which can be shifted is set such that the temperature gradient of the other fixing roller is cancelled, and then the one fixing roller is reciprocally shifted by the rocking section.

Abstract: An image forming apparatus includes an adjustment unit that adjusts an image transfer position of the sheet of paper along a main scanning direction that is orthogonal to a transporting direction of the sheet of paper, a fixing unit that fixes on the sheet of paper an toner image using fixing rollers and performs a fluctuation of the fixing roller to the main scanning direction, a detection unit that detects whether or not the fixing rollers of the fixing unit nip the sheet of paper, and a controller. The controller controls the fixing unit to perform the fluctuation of the fixing rollers when determining that the fixing rollers of the fixing unit do not nip the sheet of paper based on a detection result of the detection unit.

Abstract: To enhance the fixing quality of a fixing device to continuously fix sheets of a plurality of sizes, a carbon nanotube sheet 75, in which a plurality of carbon nanotubes are arranged such that the longitudinal directions thereof are oriented in the same direction, is provided on the surface of a heating roller 70 so that the carbon nanotube sheet ranges from the position a predetermined distance inside and the position a predetermined distance outside of the position through which each of the both edges of a sheet P2 with smaller width dimension than a sheet P1 of the largest width dimension to be fixed passes.

Abstract: Damages on fixing members caused by paper passing through can be reduced. The registration rollers 53 and the registration oscillation roller 54 are provided on an upstream side of a fixing nip portion in a conveyance path for paper P and have a function of moving the paper P being conveyed toward the fixing nip portion, in a paper width direction, and the control section 10 performs paper oscillation control and fixing unit oscillation control in correlation with each other, the paper oscillation control in which the registration rollers 53 and the registration oscillation roller 54 are controlled to oscillate a position on which the paper P passes through, and the fixing unit oscillation control in which the fixing unit oscillation motor 36 is controlled to oscillate the fixing unit.

Abstract: Provided are an image forming apparatus, a fixing device, and an image forming system using the same, including: an image forming section for transferring a toner image onto a recording sheet; a first and second fixing rollers for thermally fixing the toner image on the recording sheet; a first and second temperature sensors each provided at a plurality of positions in a longitudinal direction of the fixing roller; and a rocking section for reciprocally shifting at least one of the fixing rollers in the longitudinal direction of the fixing roller, wherein the temperature gradient of each of the fixing rollers is detected, a central position of reciprocal shift of one fixing roller which can be shifted is set such that the temperature gradient of the other fixing roller is cancelled, and then the one fixing roller is reciprocally shifted by the rocking section.

Abstract: A variable frequency clock output circuit, comprising: a target value register which stores a target value corresponding to an arbitrarily set target frequency; an increase/decrease value register which stores an arbitrarily set increase/decrease value; an adder-subtractor which has an input portion into which a current output value is inputted and outputs a calculation result obtained by adding/subtracting the increase/decrease value stored in the increase/decrease value register to/from the current output value inputted into the input portion based on an addition/subtraction instruction signal; a comparator which compares an output value of the adder-subtractor to the target value stored in the target value register, and outputs an addition/subtraction instruction signal to the adder-subtractor until the output value of the adder-subtractor and the target value coincide; and a clock generator which outputs a clock signal having a frequency proportional to the output value of the adder-subtractor.

Abstract: To enhance the fixing quality of a fixing device to continuously fix sheets of a plurality of sizes, a carbon nanotube sheet 75, in which a plurality of carbon nanotubes are arranged such that the longitudinal directions thereof are oriented in the same direction, is provided on the surface of a heating roller 70 so that the carbon nanotube sheet ranges from the position a predetermined distance inside and the position a predetermined distance outside of the position through which each of the both edges of a sheet P2 with smaller width dimension than a sheet P1 of the largest width dimension to be fixed passes.

Abstract: An image forming apparatus that warns that a JOB fails to be pulled out is provided. Warning processes executed by a CPU of a printer that is one example of the image forming apparatus includes the steps of determining whether a JOB list is updated, setting a job counter JB_S_CTA for checking JOB at an initial value “1” and setting an upper limit counter JB_S_CTB at an upper limit value when the JOB list is updated, executing a failure-to-pull-out warning process if JOBs counted by JB_S_CTA belong to the same client, and incrementing the JB_S_CTA by “1”.

Abstract: A variable frequency clock output circuit, comprising: a target value register which stores a target value corresponding to an arbitrarily set target frequency; an increase/decrease value register which stores an arbitrarily set increase/decrease value; an adder-subtractor which has an input portion into which a current output value is inputted and outputs a calculation result obtained by adding/subtracting the increase/decrease value stored in the increase/decrease value register to/from the current output value inputted into the input portion based on an addition/subtraction instruction signal; a comparator which compares an output value of the adder-subtractor to the target value stored in the target value register, and outputs an addition/subtraction instruction signal to the adder-subtractor until the output value of the adder-subtractor and the target value coincide; and a clock generator which outputs a clock signal having a frequency proportional to the output value of the adder-subtractor.

Abstract: An image forming apparatus that warns that a JOB fails to be pulled out is provided. Warning processes executed by a CPU of a printer that is one example of the image forming apparatus includes the steps of determining whether a JOB list is updated, setting a job counter JB_S_CTA for checking JOB at an initial value “1” and setting an upper limit counter JB_S_CTB at an upper limit value when the JOB list is updated, executing a failure-to-pull-out warning process if JOBs counted by JB_S_CTA belong to the same client, and incrementing the JB_S_CTA by “1”.

Abstract: In an image forming apparatus, a black edge of a document image is emphasized, and the black edge is detected by deciding an edge from the lightness data and by deciding a black color from the chroma data. The data of cyan, magenta and yellow of a pixel at a black edge are replaced with minima of data of cyan, magenta and yellow of pixels in a prescribed region around the pixel. In order to prevent erroneous decision of a black edge, if a number of isolated pixels is larger than a threshold level, a decision as a pixel at a black edge is invalidated. Automatic exposure can be performed on a color document for correcting a background of the document obtained in a prescan. The background level of the document is determined only on pixels decided to be black. When color balance is adjusted on one of the data of cyan, magenta, yellow and black, the density is kept constant.

Abstract: In an image forming apparatus, a black edge of a document image is emphasized, and the black edge is detected by deciding an edge from the lightness data and by deciding a black color from the chroma data. The data of cyan, magenta and yellow of a pixel at a black edge are replaced with minima of data of cyan, magenta and yellow of pixels in a prescribed region around the pixel. In order to prevent erroneous decision of a black edge, if a number of isolated pixels is larger than a threshold level, a decision as a pixel at a black edge is invalidated. Automatic exposure can be performed on a color document for correcting a background of the document obtained in a prescan. The background level of the document is determined only on pixels decided to be black. When color balance is adjusted on one of the data of cyan, magenta, yellow and black, the density is kept constant.

Abstract: In an image forming apparatus, a black edge of a document image is emphasized, and the black edge is detected by deciding an edge from the lightness data and by deciding a black color from the chroma data. The data of cyan, magenta and yellow of a pixel at a black edge are replaced with minima of data of cyan, magenta and yellow of pixels in a prescribed region around the pixel. In order to prevent erroneous decision of a black edge, if a number of isolated pixels is larger than a threshold level, a decision as a pixel at a black edge is invalidated. Automatic exposure can be performed on a color document for correcting a background of the document obtained in a prescan. The background level of the document is determined only on pixels decided to be black.

Abstract: In an image forming apparatus, a black edge of a document image is emphasized, and the black edge is detected by deciding an edge from the lightness data and by deciding a black color from the chroma data. The data of cyan, magenta and yellow of a pixel at a black edge are replaced with minima of data of cyan, magenta and yellow of pixels in a prescribed region around the pixel. In order to prevent erroneous decision of a black edge, if a number of isolated pixels is larger than a threshold level, a decision as a pixel at a black edge is invalidated. Automatic exposure can be performed on a color document for correcting a background of the document obtained in a prescan. The background level of the document is determined only on pixels decided to be black. When color balance is adjusted on one of the data of cyan, magenta, yellow and black, the density is kept constant.

Abstract: An image forming apparatus is composed of an image holding component for holding an image, a first image forming device and a second image forming device for respectively forming a first image and a second image on a surface of the image holding component, a switching unit for switching a mode between a first mode and a second mode, the first mode being where the first image forming device and the second image forming device come into contact with the image holding component and the second mode being where the second image forming device and the image holding component do not come into contact and the first image forming device comes into contact with the image holding component, a detecting unit for detecting information concerning an image formed on the image holding component, and a modifying unit for modifying at least one of an image forming condition for the first image and an image forming condition for the second image in accordance with the information detected by the detecting unit.

Abstract: An image forming apparatus operates in a color mode using a plurality of image holding components and in a monochrome mode using one of the plurality of image holding components to perform the image formation. The mode is switched between the color mode and the monochrome mode in accordance with information, such as the number of monochrome images having been successively formed, the number of monochrome images to be successively formed, a time period having been taken for the monochrome image formation, productivity or life priority specified the user, and a standby state of the image forming apparatus in the color mode or the monochrome mode, with a distance between the recording sheets to be transported being controlled according to predetermined conditions.

Abstract: In an image processor, an image of document is read by an image sensor. A reduction ratio of the image is set. Then, interpolation is performed on the image data between a pixel under interest and a pixel adjacent to the pixel under interest according to the reduction ratio. After the interpolation, pixel data in the image data are thinned out to an image data having a size determined by the reduction ratio, and an image is formed on a sheet of paper based on the thined-out data. Because the interpolation is performed before the thinning-out of the image data, defects in a reduced image such as vanishment of a narrow line are reduced, and image quality is improved.