Abstract: In an image forming apparatus mountable a detachable unit mounting a memory in a main body of the apparatus, a memory-access-reservation control unit for accepting a request of an access with respect to a nonvolatile memory provided in a process cartridge in which a photosensitive drum, a toner and the like are integrated is provided in an engine control unit. When there is a request of an access with respect to the nonvolatile memory from a printer controller, the memory-access-reservation control unit accesses the nonvolatile memory in accordance with the request of the access. Upon completion of the access, the fact is notified to the printer controller. In response to the notification, the printer controller requests transmission of read information or confirms that a writing operation has been normally ended, by communicating with the engine control unit.

Abstract: An engine control unit of a printer engine checks the status of each part of the printer, and if there is any change in the status, generates a predetermined representative status of changes and outputs a status change signal to a controller (RIP). The controller is informed of a change in the status by the status change signal, and reads the predetermined representative status to discriminate the changed status from unchanged statuses. In accordance with the discriminated status, the current status can be read. Accordingly, it is not necessary to periodically read the statuses, improving the efficiency of an image forming process. A status change informing control unit in the engine control unit sets a changing status bit of a basic status or status change signal and sends it to the controller, when there occurs a change in any data of a presence/absence and paper size of a paper sheet at a paper feeding port and a loading state of an optional paper feeder.

Abstract: An engine control unit of a printer engine checks the status of each part of the printer, and if there is any change in the status, generates a predetermined representative status of changes and outputs a status change signal to a controller (RIP). The controller is informed of a change in the status by the status change signal, and reads the predetermined representative status to discriminate the changed status from unchanged statuses. In accordance with the discriminated status, the current status can be read. Accordingly, it is not necessary to periodically read the statuses, improving the efficiency of an image forming process. A status change informing control unit in the engine control unit sets a changing status bit of a basic status or status change signal and sends it to the controller, when there occurs a change in any data of a presence/absence and paper size of a paper sheet at a paper feeding port and a loading state of an optional paper feeder.

Abstract: An image forming apparatus includes a light beam generator for generating a light beam, a rotational polygon mirror for scanning the light beam generated by the light beam generator across a member to be illuminated, a rotation detector for detecting whether or not the rotational polygon mirror rotates at a predetermined rotation number for an image formation, and a determining device for determining whether or not the rotational polygon mirror rotates at the predetermined rotation number stably in accordance with an output from the rotation detector.

Abstract: An image output control apparatus is constructed by a converter for converting first information to second information, a controller for starting an output preparing operation before the conversion of the first information of one page to the second information, a memory for holding a control value determined during the output preparing operation, a unit for temporarily stopping the output preparing operation, and a unit for restarting the output preparing operation, wherein the output preparing operation to be restarted is executed on the basis of the control value held in the memory.

Abstract: An image forming apparatus which converts character or pattern information into bit map information (pixel information) and forms an image based thereon. The image forming apparatus includes a light-beam generator for generating a modulated light beam, a light-beam deflector for scanning an image carrier, a device for feeding a sheet to registration rollers and a driver for driving the image carrier. A time period is provided to operate the light-beam deflector and the feeding device before the driver starts to drive the image carrier to form an image.

Abstract: An image forming apparatus includes image forming device for forming an image on a recording material, the image forming device including an image bearing member, a charging member for charging the image bearing member and a voltage source for supplying a voltage to the charging member; and determining device for determining a substantial intersection between an actual voltage-current characteristic curve between the charging member and the image bearing member and a predetermined voltage-current curve predetermined for the charging member, and for determining a bias to be applied to the charging member during image forming operation of the basis of the intersection.

Abstract: An image forming apparatus comprises image information which outputs a sync signal and means generated image information synchronously with the sync signal; image forming means form an image on the basis of the image information at either one of a plurality of resolutions and which generates a sync request signal to request a transmission of the sync signal; and a resolution changeover means. When the image forming unit received the resolution change over request signal before the sync request signal is generated, the image forming unit executes the switching operation of the resolution, and if the image forming unit received the resolution changeover request signal after the sync request signal had been generated, the image forming unit does not execute the switching operation of the resolution.

Abstract: An image forming apparatus for scanning a light beam modulated in accordance with image information using a rotational polygon mirror comprises a light beam generator for generating the light beam, an adjuster for adjusting the light quantity of the light beam generated by the light beam generator, a driver for driving the rotational polygon mirror in rotation, and a detector for detecting whether the rotational number of the rotational polygon mirror reaches a predetermined rotation number within a predetermined time. The light quantity adjuster starts the light quantity adjustment after the start of driving of the rotational polygon mirror with the driver, and before the rotation number of the rotational polygon mirror reaches the predetermined rotation number.

Abstract: A fixing device is provided with a heating member heated by a heater, a temperature detecting member for detecting a temperature of the heating member, a controller for controlling energization of the heater so that the temperature detected by the temperature detection member becomes equal to a predetermined fixing temperature in a fixing mode, and becomes equal to a predetermined stand-by temperature lower than the fixing temperature in a stand-by mode, and a measurement unit for measuring a temperature rise rate of the heater, wherein the controller controls determination of the stand-by temperature and a switching timing from the stand-by temperature to the fixing temperature on the basis of a measurement result from the measurement unit.

Abstract: An image forming apparatus includes a feeder means and a recorder. The feeder feeds a sheet of recording paper to a predetermined position in response to a spare paper feed signal instructing the feeding of the sheet of recording paper to the predetermined position preliminarily, and then feeds the sheet of recording paper being stopped at the predetermined position again in response to a record request signal. The recorder records an image on the sheet of recording paper fed by the feeder means through an electrophotographic process. The recorder means starts preparation to execute the electrophotographic process upon receiving the spare paper feed signal. As a result throughput is increased without causing other problems.

Abstract: An image forming apparatus for adjusting image density includes an input device for inputting a plurality of image type information and a discriminating device for discriminating the image type information in accordance with a signal other than a signal to be recorded. An image forming circuit, such as a printer, forms an image on the basis of image type information. A density adjusting circuit adjusts the image forming density of the image forming circuit in accordance with the input image type information. The discriminating device inputs a signal indicative of whether the input image type information indicates a text image or a graphics image, or whether it denotes Japanese or a European language (e.g., English). The discriminating device also inputs a signal indicative of the kind of font included in the input image type information or a signal indicative of a resolution for an output image to be formed by the printer.

Abstract: An image forming apparatus which can adjust a density comprises: a first input device to input image information; a second input device to input the kind of image information; an image forming circuit such as a printer form an image on the basis of image information which can vary an image forming density; and a density adjusting circuit to adjust the image forming density of the image forming circuit in accordance with the kind of input image information. The second input device inputs a signal indicative of whether the input image information indicates a text image or a graphics image or whether it denotes Japanese or European/English language. The second input device inputs a signal indicative of the kind of font included in the input image information or a signal indicative of a resolution of an output image which is formed by the printer.

Abstract: An image forming apparatus comprises image information which outputs a sync signal and generated image information synchronously with the sync signal; an image forming apparatus forms an image on the basis of the image information at either one of a plurality of resolutions and which generates a sync request signal to request a transmission of the sync signal; and a resolution changeover means.When the image forming unit received the resolution change over request signal before the sync request signal is generated, the image forming unit executes the switching operation of the resolution, and if the image forming unit received the resolution changeover request signal after the sync request signal had been generated, the image forming unit does not execute the switching operation of the resolution.

Abstract: An image forming apparatus comprises includes a feeder means and recorder. The feeder feeds a sheet of recording paper to a predetermined position in response to a spare paper feed signal instructing the feeding of the sheet of recording paper to the predetermined position preliminarily, and then feeds the sheet of recording paper being stopped at the predetermined position again in response to a record request signal. The recorder records an image on the sheet of recording paper fed by the feeder means through an electrophotographic process. The recorder means starts preparation to execute the electrophotographic process upon receiving the spare paper feed signal. As a result, throughput is increased without causing other problems.

Abstract: In an image forming apparatus having a pre-paper-feed function to previously convey a paper to a predetermined position before a print request, after a device for generating a pre-paper-feed requests has generated the pre-paper-feed request, the pre-paper-feed request can be made invalid.

Abstract: A driver IC for driving a light source comprises means for generating a constant current, switching means for switching the constant current supplied to the light source, first input terminal for inputting a first signal to modulate a light emitted by the light source, said switching means performing a switching operation in accordance with the first signal, and second input terminal for inputting a second signal so as to supply the constant current to the light source, irrespective of the first signal.

Abstract: A communication system includes a main control unit controlling a plurality of units, a transmitter for transmitting information between the main control unit and the plurality of units, and an error detector. The error detector can include a modulator and demodulator for modulating or demodulating the transmitted information on the basis of a predetermined rule. The error detector detects a communication error in the transmitted information in accordance with the predetermined rule. Alternatively, the error detector can include a transmitted data creator/analyzer for creating data based on the transmitted information in a state in which the information contains positive data and negative data of the same bit in one frame and analyzes data when the data is received. This error detector detects a communication error in the transmitted information on the basis of the comparison between the positive and negative data.

Abstract: An image forming apparatus includes a detecting unit that detects the size of a recording medium and a designating unit that designates the size of a recording medium onto which an image is to be recorded. The comparing unit compares the detected size with the designated size to determine which size is larger and a control unit controls the apparatus to perform operations such that an operation when the detected size is larger than the designated size is different from that when the detected size is smaller than the designated size.

Abstract: An image forming apparatus includes a feeder means and a recorder. The feeder feeds a sheet of recording paper to a predetermined position in response to a spare paper feed signal instructing the feeding as the sheet of recording paper to the predetermined position preliminarily, and then feeds the sheet of recording paper being stopped at the predetermined position again in response to a record request signal. The recorder records an image on the sheet of recording paper fed by the feeder means through an electrophotographic process. The recorder means starts preparation to execute the electrophotographic process upon receiving the spare paper feed signal. As a results, throughput is increased without causing other problems.