Abstract: An image forming apparatus includes a movable endless belt, a toner image forming unit, a movable transfer member, a voltage source, a setting portion. When a maximum cumulative value in a case where a length in which an adjusting toner image is formed with respect to a movement direction of the belt at a plurality position with respect to a widthwise direction of the belt perpendicular to the movement direction is accumulated is defined as a representative cumulative value, the setting portion sets the second voltage when the adjusting toner image passing through the transfer portion is a first adjusting toner image so as to be lower than the second voltage when the adjusting toner image passing through the transfer portion is a second adjusting toner image smaller in representative cumulative value than the first adjusting toner image.

Abstract: An image forming apparatus includes an image bearing member, a voltage source, a fixing device including a rotatable member, an executing portion for executing an operation in a both side mode, and a setting portion. The setting portion sets a transfer voltage in the operation for a second surface so that an absolute value of the transfer voltage when a recording material region, which starts from a most downstream end position and which passed through a fixing portion through a first one full circumference of the rotatable member when the toner image is fixed on a first surface passes through the transfer portion, is greater than an absolute value of the transfer voltage when a recording material region passed through the fixing portion through a second one full circumference of the rotatable member when the toner image is fixed on the first surface passes through the transfer portion.

Abstract: An image forming apparatus includes: an image bearing member; a toner image forming unit; a belt member; a transfer member; a transfer voltage source for generating a voltage applied to the transfer member; an obtaining portion for obtaining information on an electric resistance of the belt member; a detecting member for optically detecting a test toner image formed on the image bearing member and transferred on the belt member; and an executing portion for executing, on the basis of a detection result of the test toner image by the detecting member, an adjusting operation for adjusting an image forming condition of the toner image forming unit. The executing portion sets, on the basis of the information, a voltage applied to the transfer member when the test toner image is transferred onto the belt member in the adjusting operation.

Abstract: An image forming apparatus includes a photosensitive member, a charging member, a charging voltage source, an exposure device, a developing device, a transfer member, a transfer voltage source, a voltage detecting portion, a current detecting portion, and an executing portion. In a test mode, the executing portion gradually changes a value of a current caused to flow through the transfer member from zero to a predetermined target transfer current and sets the current caused to flow through the transfer member as the predetermined target transfer current, and then gradually changes a current caused to flow through the charging member from zero to an obtained charging current when a region of the photosensitive member subsequently passes through the charging portion and sets the current caused to flow through the charging member when a region of the photosensitive member subsequently passes through the charging portion as the obtained charging current.

Abstract: An image forming apparatus includes a movable endless belt, a toner image forming unit, a movable transfer member, a voltage source, a setting portion. When a maximum cumulative value in a case where a length in which an adjusting toner image is formed with respect to a movement direction of the belt at a plurality position with respect to a widthwise direction of the belt perpendicular to the movement direction is accumulated is defined as a representative cumulative value, the setting portion sets the second voltage when the adjusting toner image passing through the transfer portion is a first adjusting toner image so as to be lower than the second voltage when the adjusting toner image passing through the transfer portion is a second adjusting toner image smaller in representative cumulative value than the first adjusting toner image.

Abstract: An image forming apparatus includes an image bearing member, a transfer member, a constant voltage source for applying a transfer voltage and a returning voltage, a detecting member for detecting a current flowing through the constant voltage source, and a setting portion for setting a falling time. When falling of the transfer voltage is started, after switching from the returning voltage to the transfer voltage is started at first switching timing before the recording material enters the transfer portion, at second switching timing after the recording material passes through the transfer portion, the setting portion sets the falling time which is a time from the second switching timing until a current flowing through the transfer member is zero on the basis of a detection result of the detecting member in a period after the first switching timing and before entering of the recording material into the transfer portion.

Abstract: An image forming apparatus includes: an image bearing member; a toner image forming unit; a belt member; a transfer member; a transfer voltage source for generating a voltage applied to the transfer member; an obtaining portion for obtaining information on an electric resistance of the belt member; a detecting member for optically detecting a test toner image formed on the image bearing member and transferred on the belt member; and an executing portion for executing, on the basis of a detection result of the test toner image by the detecting member, an adjusting operation for adjusting an image forming condition of the toner image forming unit. The executing portion sets, on the basis of the information, a voltage applied to the transfer member when the test toner image is transferred onto the belt member in the adjusting operation.

Abstract: An image forming apparatus includes a photosensitive member, a charging member, a charging voltage source, an exposure device, a developing device, a transfer member, a transfer voltage source, a voltage detecting portion, a current detecting portion, and an executing portion. In a test mode, the executing portion gradually changes a value of a current caused to flow through the transfer member from zero to a predetermined target transfer current and sets the current caused to flow through the transfer member as the predetermined target transfer current, and then gradually changes a current caused to flow through the charging member from zero to an obtained charging current when a region of the photosensitive member subsequently passes through the charging portion and sets the current caused to flow through the charging member when a region of the photosensitive member subsequently passes through the charging portion as the obtained charging current.

Abstract: An image forming apparatus includes: an image bearing member; a voltage source; a fixing device including a rotatable member; an executing portion for executing an operation in a both-side mode; and a setting portion. The setting portion sets a transfer voltage in the operation for a second surface so that an absolute value of the transfer voltage when a recording material region which starts from a downstreammost end position and which passed through a fixing portion through first one full circumference of the rotatable member when the toner image is fixed on a first surface passes through the transfer portion is larger than an absolute value of the transfer voltage when a recording material region passed through the fixing portion through second one full circumference of the rotatable member when the toner image is fixed on the first surface passes through the transfer portion.

Abstract: An image forming apparatus includes a first image forming portion including a first photosensitive member, a first charging member to electrically charge the first photosensitive member, and a first exposure member to expose to light the charged first photosensitive member to form an electrostatic latent image, and a second image forming portion including a second photosensitive member, a second charging member to electrically charge the second photosensitive member, and a second exposure member to expose to light the charged second photosensitive member to form an electrostatic latent image.

Abstract: An image forming apparatus includes a plurality of image bearing members; a rotatable intermediary transfer member for carrying toner images transferred from the plurality of image bearing members in contact with the plurality of image bearing members; a transfer member for press-contacting to the intermediary transfer member to form a transfer portion, at which the toner images on the intermediary transfer member are to be transferred onto a recording material; and a control portion for controlling an image forming operation so that, during execution of a continuous image forming mode in which images are formed on a plurality of recording materials conveyed with a preset minimum interval, a recording material passes through the transfer portion and thereafter transfer of a toner image to be formed on a subsequent recording material from an image bearing member, located upstream of the transfer portion and most downstream of the plurality of image bearing members with respect to a rotational direction of the

Abstract: An image forming apparatus includes a first image forming portion including a first photosensitive member (drum), a first charging device, a first exposure device, a first developing device, and a first transfer device; a second image forming portion including a second drum, and a second charging device, a second exposure device, a second developing device, and a second transfer device; a power source for applying a common voltage to the first transfer device and the second transfer device; and a setting device for variably setting, for a period in which the transfer operation is performed, potentials of the exposed portions of the first and second drums on the basis of currents passing through the first and second transfer devices, respectively, when the common voltage is applied to the first and second transfer devices in a period other than the period in which the transfer operation is performed.

Abstract: An image forming apparatus is provided in which image forming sections are provided along an intermediate transfer member and in which a test voltage is applied to a transfer member to control a transfer voltage. In the image forming apparatus, the test voltage is applied to a region of the intermediate transfer member in an upstream image forming section. The test voltage is controlled so as to be applied at a time except when that region of the intermediate transfer member passes through a downstream image forming section. Accordingly, when the intermediate transfer member is charged by applying the test voltage to the transfer member in the upstream image forming section, the transfer voltage can be appropriately controlled in the downstream image forming section.

Abstract: An image forming apparatus includes first and second image forming units respectively including first and second photosensitive members and first and second toner image forming devices for forming a toner image on the first and second photosensitive members respectively, and first and second transfer members configured to transfer the toner image formed on the first and second photosensitive members onto the belt member. The second image forming unit is arranged on a downstream side of the first image forming unit and is adjacent to the first image forming unit. An image forming apparatus further includes first and second photodischarging devices for discharging potential of the first and second photosensitive members respectively by irradiating thereon with light, wherein the first photodischarging device is turned off when the current is detected by applying the voltage to the second transfer member.

Abstract: An image forming apparatus includes first and second image forming units respectively including first and second photosensitive members and first and second toner image forming devices for forming a toner image on the first and second photosensitive members respectively, and first and second transfer members configured to transfer the toner image formed on the first and second photosensitive members onto the belt member. The second image forming unit is arranged on a downstream side of the first image forming unit and is adjacent to the first image forming unit. An image forming apparatus further includes first and second photodischarging devices for discharging potential of the first and second photosensitive members respectively by irradiating thereon with light, wherein the first photodischarging device is turned off when the current is detected by applying the voltage to the second transfer member.

Abstract: An image forming apparatus is provided in which image forming sections are provided along an intermediate transfer member and in which a test voltage is applied to a transfer member to control a transfer voltage. In the image forming apparatus, the test voltage is applied to a region of the intermediate transfer member in an upstream image forming section. The test voltage is controlled so as to be applied at a time except when that region of the intermediate transfer member passes through a downstream image forming section. Accordingly, when the intermediate transfer member is charged by applying the test voltage to the transfer member in the upstream image forming section, the transfer voltage can be appropriately controlled in the downstream image forming section.

Abstract: There is provided an image forming apparatus including a belt which conveys images, first rollers which support the belt and a second roller which supports the aforementioned belt at its surface opposite from the surface supported by the aforementioned first rollers, wherein the image forming apparatus rotates the aforementioned belt at a first speed and rotates the aforementioned belt at a second speed smaller than the aforementioned first speed or stops the aforementioned belt when the portions of the aforementioned belt which have been supported by the aforementioned first rollers at the time of stoppage of the aforementioned belt are supported by the aforementioned second roller, prior to image formation after the stoppage of the aforementioned belt.

Abstract: An image forming apparatus includes a plurality of image bearing members; a rotatable intermediary transfer member for carrying toner images transferred from the plurality of image bearing members in contact with the plurality of image bearing members; a transfer member for press-contacting to the intermediary transfer member to form a transfer portion, at which the toner images on the intermediary transfer member are to be transferred onto a recording material; and a control portion for controlling an image forming operation so that, during execution of a continuous image forming mode in which images are formed on a plurality of recording materials conveyed with a preset minimum interval, a recording material passes through the transfer portion and thereafter transfer of a toner image to be formed on a subsequent recording material from an image bearing member, located upstream of the transfer portion and most downstream of the plurality of image bearing members with respect to a rotational direction of the

Abstract: There is provided an image forming apparatus including a belt which conveys images, first rollers which support the belt and a second roller which supports the aforementioned belt at its surface opposite from the surface supported by the aforementioned first rollers, wherein the image forming apparatus rotates the aforementioned belt at a first speed and rotates the aforementioned belt at a second speed smaller than the aforementioned first speed or stops the aforementioned belt when the portions of the aforementioned belt which have been supported by the aforementioned first rollers at the time of stoppage of the aforementioned belt are supported by the aforementioned second roller, prior to image formation after the stoppage of the aforementioned belt.