Abstract: An image forming apparatus forming a preferable image without white dots caused by excessive charging when a halftone image is formed by providing a potential difference between a surface potential of a photosensitive drum immediately before charging by a charging device, and that of the drum after the charging in an image forming area of the drum. At least one of a charging bias and a transfer bias is changed between a first area and a second area. The first area is an area on the drum that passes a transfer portion when a recording medium is not present between the roller and the drum, and on that a latent image is to be formed. The second area is an area on the drum that passes the transfer portion when the medium is present between the roller and the drum, and on that a latent image is to be formed.

Abstract: An image forming apparatus forming a preferable image without white dots caused by excessive charging when a halftone image is formed by providing a potential difference between a surface potential of a photosensitive drum immediately before charging by a charging device, and that of the drum after the charging in an image forming area of the drum. At least one of a charging bias and a transfer bias is changed between a first area and a second area. The first area is an area on the drum that passes a transfer portion when a recording medium is not present between the roller and the drum, and on that a latent image is to be formed. The second area is an area on the drum that passes the transfer portion when the medium is present between the roller and the drum, and on that a latent image is to be formed.

Abstract: An image forming apparatus has a first image formation mode for forming an image on an image bearing member by using developer under a first predetermined image forming condition and a second image formation mode for forming an image on an image bearing member by using developer under a second image forming condition which is different from the first predetermined image forming condition and is set so that an amount of consumption of developer with respect to an identical image in the second image formation mode is smaller than that in the first image formation mode, the apparatus includes storing means for storing information for setting the second image forming condition corresponding to a plurality of levels of an amount of usage of the image bearing member, and control means for changing the second image forming condition in the second image formation mode depending on an amount of usage of the image bearing member and information stored in the storing means.

Abstract: An image forming apparatus has a first image formation mode for forming an image on an image bearing member by using developer under a first predetermined image forming condition and a second image formation mode for forming an image on an image bearing member by using developer under a second image forming condition which is different from the first predetermined image forming condition and is set so that an amount of consumption of developer with respect to an identical image in the second image formation mode is smaller than that in the first image formation mode, the apparatus includes storing means for storing information on an amount of usage of the image bearing member, and control means for changing the second image forming condition in the second image formation mode depending on the information stored in the storing means.

Abstract: A developing apparatus includes a rotatable, developer carrying body for carrying a one-component developer and a rotatable, agitating member for agitating the one-component developer. The one-component developer is magnetic toner at least containing a bonding resin and magnetic iron oxide. When wettability of the magnetic toner relative to a mixture solution of methanol and water is measured at the transmittance of light having a wavelength of 780 nm, a methanol concentration at the transmittance of 80% is within the range of 45 to 65 volume %, and wherein 0.1?b/a?0.2 is established where a (rps) denotes the rotation speed of the developer carrying body, and b (rps) denotes the rotation speed of the agitating member.

Abstract: A developing blade member for regulating a thickness of a layer of a developer on a peripheral surface of a rotatable developing roller enclosing a magnet roller, wherein a scraper for scraping the developer toward longitudinally inside of the developing roller is provided at a longitudinal end of the developing roller, the developing blade member including an elastic member for regulating the thickness of the layer of the developer on the peripheral surface of the developing roller; a metal plate for supporting the elastic member; a projection projecting toward the developing roller, the projection being provided at each of longitudinal ends of the metal plate, wherein an inside end of the projection, with respect to the longitudinal direction of the developing roller, is disposed inside of an inside end of the scraper and in a non-image-formation region.

Abstract: An image forming apparatus has full- and half-speeds as image forming speeds. In the full-speed mode, a detected voltage value conforming to the electrostatic capacity between a developing roller and plate antenna of a process cartridge is converted to the amount of toner remaining in the apparatus. In the half-speed mode, on the other hand, the amount of remaining toner is found using a value obtained by adding a correction value ? to the detected voltage value conforming to the electrostatic capacity between the developing roller and the plate antenna. As a result, the amount of toner can be sensed accurately even if the electrification conditions of an image carrier change.

Abstract: In an image forming apparatus that is capable of forming an image in a plurality of image forming modes that correspond to frequencies of developing bias, a voltage value that reflects the image forming mode and amount of remaining toner is corrected using a correction quantity that conforms to the image forming mode.

Abstract: An image forming apparatus of an electrophotography system, in which 10<PS/|Hz1−Hz2| is satisfied where Hz1 indicates a frequency of charging bias, Hz2 indicates a frequency of developing bias, and PS indicates a peripheral speed of a photosensitive member, whereby preventing density unevenness in an image.

Abstract: The image forming apparatus of the present invention having a developer containing section and a developer remaining amount detecting member, and capable of forming an image at any of a plurality of printing speeds, has a configuration in which the averaging method of the developer remaining amount by the developer remaining amount detecting member is changed in response to the printing speed. The invention thus provides an image forming apparatus having a plurality of printing speeds, which permits successive detection of the remaining amount of developer at a high accuracy in response to the printing speed.

Abstract: A developing blade member for regulating a thickness of a layer of a developer on a peripheral surface of a rotatable developing roller enclosing a magnet roller, wherein a scraper for scraping the developer toward longitudinally inside of the developing roller is provided at a longitudinal end of the developing roller. the developing blade member including an elastic member for regulating the thickness of the layer of the developer on the peripheral surface of the developing roller; a metal plate for supporting the elastic member; a projection projecting toward the developing roller, the projection being provided at each of longitudinal ends of the metal plate. wherein an inside end of the projection. with respect to the longitudinal direction of the developing roller, is disposed inside of an inside end of the scraper and in a non-image-formation region.

Abstract: In an image forming apparatus that is capable of forming an image in a plurality of image forming modes that correspond to frequencies of developing bias, a voltage value that reflects the image forming mode and amount of remaining toner is corrected using a correction quantity that conforms to the image forming mode.

Abstract: According to the present invention, a developing apparatus includes:

Abstract: A cartridge includes a developing apparatus equipped with a developer containing portion containing a developer, a residual developer amount detecting device for detecting a residual developer amount in the developer containing portion, and a storage device capable of storing the latest residual developer amount information. An image forming apparatus includes a continuous rest time counter configured to count a continuous rest time of the image forming apparatus, and a controller which is configured to prohibit updating of the residual developer amount information to the storage device for a predetermined period after the end of the continuous rest time of the image forming apparatus when the continuous rest time counter indicates a time not shorter than a predetermined time. This structure provides an image forming apparatus and an image forming system in which no deterioration in detection accuracy occurs even if an unstable toner state occurs due to a long printing rest time.

Abstract: An image forming apparatus of an electrophotography system, in which 10<PS/|Hz1-Hz2| is satisfied where Hz1 indicates a frequency of charging bias, Hz2 indicates a frequency of developing bias, and PS indicates a peripheral speed of a photosensitive member, whereby preventing density unevenness in an image.

Abstract: An image forming apparatus has full- and half-speeds as image forming speeds. In the full-speed mode, a detected voltage value conforming to the electrostatic capacity between a developing roller and plate antenna of a process cartridge is converted to the amount of toner remaining in the apparatus. In the half-speed mode, on the other hand, the amount of remaining toner is found using a value obtained by adding a correction value &dgr; to the detected voltage value conforming to the electrostatic capacity between the developing roller and plate antenna. As a result, the amount of toner can be sensed accurately even if the electrification conditions of an image carrier change.

Abstract: The image forming apparatus of the present invention having a developer containing section and a developer remaining amount detecting member, and capable of forming an image at any of a plurality of printing speeds has a configuration in which the averaging method of the developer remaining amount by the developer remaining amount detecting member is changed in response to the printing speed. The invention thus provides an image forming apparatus having a plurality of printing speeds, which permits successive detection of the remaining amount of developer at a high accuracy in response to the printing speed.

Abstract: In the conventional types of Active Transfer Voltage Control (ATVC) system, it is assumed that transferring material has definite impedance. When a toner image is transferred to the transferring material which is in a condition where only the top of the transferring material has high impedance, the conventional ATVC system maintains a transferring current higher than the critical transferring current value with the top of the transferring material and applies a bias voltage at a corrected level, whereby the ATVC system may supply an excessive current to a portion of the photosensitive drum corresponding to a location which is other than the top having the high impedance and at which a toner image is not formed. Therefore, it is provided, an image forming apparatus which is capable of favorably transferring a toner image regardless of impedance of a transferring material.

Abstract: A cartridge includes a developing apparatus equipped with a developer containing portion containing a developer, a residual developer amount detecting device for detecting a residual developer amount in the developer containing portion, and a storage device capable of storing latest residual developer amount information. An image forming apparatus includes a continuous rest time counter for counting a continuous rest time of a driving system of the image forming apparatus, and a control device which prohibits updating of the residual developer amount information to the storage device for a predetermined interval when the continuous rest time counter indicates a time not shorter than a predetermined time. Provided are an image forming apparatus and an image forming system in which no deterioration in detection accuracy is involved even if an unstable toner state occurs due to a long printing rest time.

Abstract: The present invention provides an image forming apparatus which has an image bearing body for bearing a toner image, a transferring member for forming a nip with the image bearing body to pinch a transferring material and for transferring the toner image on the image bearing body to the transferring material, voltage applying device for applying a transfer voltage to the transferring member, voltage detecting device for detecting an applied voltage at which a predetermined current flows through the transferring member before a transferring operation, current detecting device for detecting a current flowing when a voltage based on a detected voltage of the voltage detecting device is applied to the transferring member in a condition where a tip end of the transferring material is present at the nip, and voltage determining device for determining the transfer voltage after the tip end of the transferring material, based on a detected current by the current detecting device.