Abstract: When one or more reused sheets each having a printed side and an unprinted side on which duplex printing has been performed are ejected onto an exit tray and then loaded onto a manual feed tray, an operation control section controls a sheet feed section to feed sheets alternately from a sheet feed cassette and the manual feed tray. At times at which the sheets in the sheet feed cassette are fed, the operation control section controls an image forming section to form, on the sheets fed from the sheet feed cassette, images that have been formed over the printed sides of the reused sheets in the duplex printing. At times at which the sheets loaded onto the manual feed tray are fed, the operation control section controls the image forming section to not form an image and causes the sheets to be ejected onto the exit tray.

Abstract: In an image forming apparatus, an operation control section controls a sheet conveyance section to eject, onto an exit tray, sheets on which images of an even number page group have been formed on respective first sides thereof. A reception section receives input from a user indicating whether the sheets ejected onto the exit tray after the images have been formed on the first sides thereof are new sheets having unused second sides or reused sheets having used second sides. When the ejected sheets are the new sheets, the operation control section controls an image forming section to form images of an odd number page group on the second sides of the new sheets after the new sheets have been loaded onto a manual feed tray.

Abstract: When one or more reused sheets each having a printed side and an unprinted side on which duplex printing has been performed are ejected onto an exit tray and then loaded onto a manual feed tray, an operation control section controls a sheet feed section to feed sheets alternately from a sheet feed cassette and the manual feed tray. At times at which the sheets in the sheet feed cassette are fed, the operation control section controls an image forming section to form, on the sheets fed from the sheet feed cassette, images that have been formed over the printed sides of the reused sheets in the duplex printing. At times at which the sheets loaded onto the manual feed tray are fed, the operation control section controls the image forming section to not form an image and causes the sheets to be ejected onto the exit tray.

Abstract: In an image forming apparatus, an operation control section controls a sheet conveyance section to eject, onto an exit tray, sheets on which images of an even number page group have been formed on respective first sides thereof. A reception section receives input from a user indicating whether the sheets ejected onto the exit tray after the images have been formed on the first sides thereof are new sheets having unused second sides or reused sheets having used second sides. When the ejected sheets are the new sheets, the operation control section controls an image forming section to form images of an odd number page group on the second sides of the new sheets after the new sheets have been loaded onto a manual feed tray.

Abstract: Upon restart of a job after the image forming apparatus is restored from document jam, a message that “If it is possible that the document might be damaged if fed by the document feeder, please press an escape key. If it is not possible that the document might be damaged even fed by the document feeder, please return a pack of documents to the original position” is displayed on a liquid display unit. A user checks the documents discharged and judges whether or not there is a possibility that the document might be damaged. When the user determines that there is a possibility that the document might be damaged, the user presses the “escape key”, and when the user determines that there is no possibility that the document might be damaged, the user presses a restart key.

Abstract: A checking method for checking a reloadable memory includes writing operative data in connection with a specified operation on a first portion of the reloadable memory and check data on a second portion of the reloadable memory; reading data from the second portion after writing the operative data and the check data on the reloadable memory; and judging whether the read data agrees with the written check data. A checking device for checking a reloadable memory includes a reader for reading data from a specified portion of the memory after reloading operative data and writing a check data; and a judger for judging whether the read data agrees with the check data.

Abstract: A system for communicating data between two control units each capable of executing independent operations and having a memory for operations, the system is provided with a new data generator on one control unit. The new data generator generates new data for a selected item of the other control unit. The new data is combined with address data corresponding to the selected item of the memory of the other control unit to generate transmission data. The transmission data is sent to the other control unit and the new item data is written on the memory at the address specified by the transmission data. The data communication system communicates between the two control units data for a first kind of operations and data for a second kind of operations selectively. The first kind data is communicated repeatedly while the second kind data is communicated a single time.

Abstract: An image forming apparatus with which the surface potential of the photoreceptor drum is made appropriate reliably in a relatively short time is provided with the following: a charger unit for charging the surface of the photoreceptor drum; an exposing unit for forming a latent image; a potential sensor for detecting a charge potential; and a controller for controlling outputs of the charger unit and the exposing unit. The surface potential of the photoreceptor drum is made appropriate by detecting and correcting the potential after the photoreceptor drum surface is charged at a potential close to a desired potential. After both the dark and bright portions are charged at appropriate potentials, image formation is performed.

Abstract: For an image forming apparatus having a photoreceptor whose surface is charged by a main charger unit, a function is provided that a desired electric potential is attained on the photoreceptor surface by applying a lowest main charging voltage to the charger unit. By providing a plurality of grid voltages, it is possible that there are a plurality of main charging voltages suitable for the desired surface potential, and the lowest main charging voltage and the corresponding grid voltage can be selected thereamong.

Abstract: An image forming apparatus so composed that it can be furnished with a plurality of developers, can change the developer opposed to the photosensitive body by integrally moving the corresponding developers and can compensate for the position of the corresponding developer at the compensating position thereof while changing developers. Furthermore, in the image forming apparatus, the developers are moved by a motor, the position of the developers is only compensated for when the predetermined compensating position is on a shortest moving path when changing one of the developers to another developer and the developers are always changed through the shortest moving path.

Abstract: An arrangement for communication between two CPUs which allows diagnosis of whether the cause of an interrupt in communication between the CPUs is due to a routine interrupt or a failure in the communication line. Timers generate overflow signals in the event that data from one or the other CPU is late in arriving. Lateness is determined by comparing the timer values to stored values in memory. Control units respond to the timers and switch the transmission level of the CPUs so that they pass a predetermined signal pattern between themselves, indicating that the interrupt is in effect but that communication lines are still open. When one of the CPUs fails to detect the confirmation signal, the CPU causes a communication failure to be indicated.

Abstract: A color image forming apparatus provided with an image sensor making outputs for every primary color of light through reading and resolving color images to the three primary colors thereof, can exclude unnecessary developing operation pertaining to other developing agents than one or two kinds of developing agent, by distinguishing the colors based on the output per primary color from the image sensor when the color image is read, executing the developing operation through operating only the developers to accommodate one or two kinds of developing agent in the case the color distinguished at that time is the color possible to be expressed only with one or two kinds of developing agent, on the time of reproducing the color image through repeating the developing operations by a plurality of kinds of developing agent acording to the output per primary color from the image sensor.

Abstract: In an image forming apparatus in which toner is fed to a developer unit from a toner storage container through toner conveying means provided between the toner storage container and the developer unit, the image forming apparatus comprises a toner remaining amount detector for detecting not more than a predetermined amount of toner in the toner storage container, a toner density detector for detecting the density of toner in the developer unit, and means for interrupting the image forming operation to feed the toner to the developer unit from the toner storage container through the toner conveying means when the amount of the toner in the toner storage container is larger than the predetermined amount and the density detected by the toner density detector is lower than a predetermined density.

Abstract: A multicolor image forming apparatus having a plurality of developing units respectively containing different color developers; comprising a newly selected developing unit switching timing controller for controlling the rotation of the photoreceptor and the timing for switching of the newly selected developing unit, or a previously selected developing unit switching timing controller for controlling the rotation of the photoreceptor and the switching timing of the previously selected developing unit.

Abstract: A lighting control method and an apparatus thereof which determine during the returning motion of the light source, whether the next paper is fed to the registration roller, and if it is determined that the paper is fed, the light source is caused to turn on from the point of the determination, thereby causing the going motion for the next image forming operation without causing to stay the light source at the home position.

Abstract: A magnification selecting device which is capable of continuously varying magnifications by operating either UP or DOWN key and also slowing down the speed of varying mangifications only when these magnifications are in a position close to the predetermined magnification.