Abstract: An image forming apparatus includes an image bearing member unit including a toner image carrying member, a transfer unit including a movable endless belt for transferring the toner image from the carrying member onto a transfer material, a plurality of stretching members for stretching the endless belt, and a supporting portion, provided at an end portion with respect to a widthwise direction, for supporting the stretching members. In addition, a main assembly frame is provided at a position opposing the supporting portion and includes a positioning portion for determining positions of the plurality of stretching members, wherein the supporting portion is movable relative to the main assembly frame.

Abstract: In an image forming apparatus, one of a plurality of support members supporting an intermediate transfer belt is a guide member configured to regulate the rotational direction of the intermediate transfer belt while being held in sliding contact with the intermediate transfer belt at a position opposite the secondary transfer member across the intermediate transfer belt. This guide member is equipped with a first resistor portion in sliding contact with the intermediate transfer belt and a second resistor portion of a higher electrical resistance than the first resistor portion, with the second resistor portion provided upstream of the first resistor portion in the rotational direction of the intermediate transfer belt.

Abstract: There is provided an image forming apparatus which shortens the time taken for circumference detection and measures the circumference at high precision without obstructing downsizing of the apparatus. To accomplish this, the image forming apparatus detects, at an arbitrary timing, the physical pattern of the image-formed surface of a rotation member that changes over time. In the second round, the image forming apparatus detects the second pattern at a timing a predetermined time after the arbitrary timing. By using the detected patterns, the image forming apparatus obtains information associated with the circumference of the rotation member.

Abstract: The image forming apparatus, while an image forming mode is executed, during a period from start of the image forming mode until a toner image to be transferred onto a recording material is primarily transferred onto an intermediate transfer member from one of the plurality of image bearing members, which is positioned on the uppermost stream in a rotation direction of the intermediate transfer member, a toner patch (T) is formed on at least one image bearing member and the toner patch (T) is provided to a primary transfer portion. Thus, without using waste toner as a lubricant, fluctuations in circumferential surface speed, which are generated in the intermediate transfer member during the image forming operation, may be reduced.

Abstract: There is provided an image forming apparatus including a rotation member used for image forming and a detector for detecting light from the rotation member. First waveform data of an image-formed surface used to form an image on the rotation member is acquired by the detector. Second waveform data of the image-formed surface used to form an image on the rotation member is acquired. The second waveform data includes at least part of a detected section of the first waveform data. Information on the actual circumference of the rotation member is calculated based on matching between the acquired first and second waveform data. The acquired first waveform data and second waveform data are compared to determine whether or not to use the calculated information on the circumference. When it is determined not to use the calculated information on the circumference, information on the circumference of the rotation member is recalculated.

Abstract: There is provided an image forming apparatus that accurately obtains the dynamic characteristic of the apparatus when a foreign substance is adhered to a driving roller for driving an endless belt, such as a facing roller. To accomplish this, the image forming apparatus uses an optical sensor to detect information of a foreign substance on the facing roller. When it is determined that there is no foreign substance information, the image forming apparatus executes profile detection of an intermediate transfer belt using the nominal circumference of the facing roller. When the optical sensor detects foreign substance information, the image forming apparatus measures the circumference of the facing roller, and performs profile detection of the intermediate transfer belt using the measured circumference of the facing roller.

Abstract: There is provided an image forming apparatus including a rotation member used for image forming and a detector for detecting light from the rotation member. First waveform data of an image-formed surface used to form an image on the rotation member is acquired by the detector. Second waveform data of the image-formed surface used to form an image on the rotation member is acquired. The second waveform data includes at least part of a detected section of the first waveform data. Information on the actual circumference of the rotation member is calculated based on matching between the acquired first and second waveform data. The acquired first waveform data and second waveform data are compared to determine whether or not to use the calculated information on the circumference. When it is determined not to use the calculated information on the circumference, information on the circumference of the rotation member is recalculated.

Abstract: There is provided an image forming apparatus that accurately obtains the dynamic characteristic of the apparatus when a foreign substance is adhered to a driving roller for driving an endless belt, such as a facing roller. To accomplish this, the image forming apparatus uses an optical sensor to detect information of a foreign substance on the facing roller. When it is determined that there is no foreign substance information, the image forming apparatus executes profile detection of an intermediate transfer belt using the nominal circumference of the facing roller. When the optical sensor detects foreign substance information, the image forming apparatus measures the circumference of the facing roller, and performs profile detection of the intermediate transfer belt using the measured circumference of the facing roller.

Abstract: An image forming apparatus which predicts VL fluctuates of a photosensitive drum, taking a rotation speed of the photosensitive drum during image formation into consideration, and controls the image formation based on the prediction, for always obtaining an image of a stable density. The image forming apparatus performs appropriate image formation control by controlling image forming conditions based on a photosensitive member rotation time, a photosensitive member stop time, a temperature of the environment, an absolute humidity of the environment, and the rotation speed of the photosensitive member.

Abstract: There is provided an image forming apparatus including a rotation member used for image forming and a detector for detecting light from the rotation member. First waveform data of an image-formed surface used to form an image on the rotation member is acquired by the detector. Second waveform data of the image-formed surface used to form an image on the rotation member is acquired. The second waveform data includes at least part of a detected section of the first waveform data. Information on the actual circumference of the rotation member is calculated based on matching between the acquired first and second waveform data. The acquired first waveform data and second waveform data are compared to determine whether or not to use the calculated information on the circumference. When it is determined not to use the calculated information on the circumference, information on the circumference of the rotation member is recalculated.

Abstract: There is provided an image forming apparatus that accurately obtains the dynamic characteristic of the apparatus when a foreign substance is adhered to a driving roller for driving an endless belt, such as a facing roller. To accomplish this, the image forming apparatus uses an optical sensor to detect information of a foreign substance on the facing roller. When it is determined that there is no foreign substance information, the image forming apparatus executes profile detection of an intermediate transfer belt using the nominal circumference of the facing roller. When the optical sensor detects foreign substance information, the image forming apparatus measures the circumference of the facing roller, and performs profile detection of the intermediate transfer belt using the measured circumference of the facing roller.

Abstract: An image forming apparatus which predicts VL fluctuations of a photosensitive drum in consideration of a double-sided print mode, and performs an image formation control based on the prediction, and thus always obtains a stable density image. The image forming apparatus performs an appropriate image formation control by controlling an image forming condition based on a photosensitive member rotation time, a photosensitive member stop time, a temperature of an atmospheric environment, an absolute humidity of the atmospheric environment, and whether an image formation that precedes a subsequent image formation is performed in single-sided printing or double-sided printing.

Abstract: A color image forming apparatus in which a positional displacement detection image and a light quantity adjustment image are formed within a one-rotation length of an image bearing member (intermediate transfer belt). A light-emission quantity when detecting density is determined on the basis of a detection result of a light quantity adjustment image formed within the one-rotation length using light-emission quantity that is provided when light is emitted to the positional displacement detection image. This allows, for example, image density control to be performed quickly while precision of the image density control is maintained.

Abstract: There is provided an image forming apparatus that accurately obtains the dynamic characteristic of the apparatus when a foreign substance is adhered to a driving roller for driving an endless belt, such as a facing roller. To accomplish this, the image forming apparatus uses an optical sensor to detect information of a foreign substance on the facing roller. When it is determined that there is no foreign substance information, the image forming apparatus executes profile detection of an intermediate transfer belt using the nominal circumference of the facing roller. When the optical sensor detects foreign substance information, the image forming apparatus measures the circumference of the facing roller, and performs profile detection of the intermediate transfer belt using the measured circumference of the facing roller.

Abstract: There is provided an image forming apparatus including a rotation member used for image forming and a detector for detecting light from the rotation member. First waveform data of an image-formed surface used to form an image on the rotation member is acquired by the detector. Second waveform data of the image-formed surface used to form an image on the rotation member is acquired. The second waveform data includes at least part of a detected section of the first waveform data. Information on the actual circumference of the rotation member is calculated based on matching between the acquired first and second waveform data. The acquired first waveform data and second waveform data are compared to determine whether or not to use the calculated information on the circumference. When it is determined not to use the calculated information on the circumference, information on the circumference of the rotation member is recalculated.

Abstract: An image forming apparatus which predicts VL fluctuations of a photosensitive drum in consideration of a double-sided print mode, and performs an image formation control based on the prediction, and thus always obtains a stable density image. The image forming apparatus performs an appropriate image formation control by controlling an image forming condition based on a photosensitive member rotation time, a photosensitive member stop time, a temperature of an atmospheric environment, an absolute humidity of the atmospheric environment, and whether an image formation that precedes a subsequent image formation is performed in single-sided printing or double-sided printing.

Abstract: An image forming apparatus which predicts VL fluctuates of a photosensitive drum, taking a rotation speed of the photosensitive drum during image formation into consideration, and controls the image formation based on the prediction, for always obtaining an image of a stable density. The image forming apparatus performs appropriate image formation control by controlling image forming conditions based on a photosensitive member rotation time, a photosensitive member stop time, a temperature of the environment, an absolute humidity of the environment, and the rotation speed of the photosensitive member.

Abstract: There is provided an image forming apparatus which shortens the time taken for circumference detection and measures the circumference at high precision without obstructing downsizing of the apparatus. To accomplish this, the image forming apparatus detects, at an arbitrary timing, the physical pattern of the image-formed surface of a rotation member that changes over time. In the second round, the image forming apparatus detects the second pattern at a timing a predetermined time after the arbitrary timing. By using the detected patterns, the image forming apparatus obtains information associated with the circumference of the rotation member.

Abstract: A color image forming apparatus in which a positional displacement detection image and a light quantity adjustment image are formed within a one-rotation length of an image bearing member (intermediate transfer belt). A light-emission quantity when detecting density is determined on the basis of a detection result of a light quantity adjustment image formed within the one-rotation length using light-emission quantity that is provided when light is emitted to the positional displacement detection image. This allows, for example, image density control to be performed quickly while precision of the image density control is maintained.