Abstract: An image forming apparatus including an image bearer, a transfer-bias power source, an environment sensor, and a controller. The controller controls the transfer-bias power source to change the DC component and the AC component, according to the at least one of temperature and humidity detected by the environment sensor and a duty of the transfer bias. The duty is A/(A+B)×100[%] where A denotes an area on a return-directional side to move toner from the recording sheet back to the image bearer, relative to a center value (Voff) of a maximum value and a minimum value of the transfer bias in one cycle of a waveform of the transfer bias, and B denotes an area on a transfer-directional side to move the toner from the image bearer to the recording sheet, relative to the center value (Voff) in the one cycle.

Abstract: An improved image forming apparatus includes an image bearer, a nip forming member, a transfer power source, and a controller. The controller switches a transfer mode between a first mode to transfer the toner image onto a first type sheet having a surface smoothness higher than a surface smoothness of a second type sheet and a second mode to transfer the toner image onto the second type sheet. The controller controls the transfer power source to output the transfer bias having an opposite-peak duty of greater than or equal to 50% that is a duty on the side of the opposite-peak value in the first mode. The controller controls the transfer power source to output the transfer bias having an opposite-peak duty of less than 50%, which is different from the opposite-peak duty of the first mode, in the second mode.

Abstract: An image forming apparatus includes a belt-shaped image bearer, a transferer, a guide, two rotators, and a support. The image bearer has an image bearing surface to bear an image thereon. The transferer forms a transfer section between the transferer and the image bearer, to transfer the image onto a recording medium. The guide is disposed upstream from the transfer section in a delivery direction of the recording medium, to guide the recording medium toward the transfer section. The two rotators are disposed upstream from the transfer section in a moving direction of the image bearer and in contact with a non-image bearing surface of the image bearer opposite to the image bearing surface, a first rotator being closer to the transfer section than a second rotator. The support supports the first rotator and the guide and adjusts a position of the first rotator and a position of the guide.

Abstract: An image forming apparatus includes a developing device, an image bearer, a transfer rotator, a blade contacting a surface of the transfer rotator, and a controller to control the developing device, the image bearer, and the transfer rotator. A first toner pattern image is formed on the image bearer, transferred onto the transfer rotator, and passed past the blade at least twice together with rotation of the transfer rotator in at start-up of the image forming apparatus. A second toner pattern image is formed on the image bearer after the start-up and during passage of a non-image area in which toner images are not formed. A range of the first toner pattern image is wider than a range of the second toner pattern image in a width direction perpendicular to a direction of travel of the image bearer.

Abstract: A transfer device includes an image bearer, a rotatable body, a solid lubricant assembly, and a guide. An image bearer bears an image. The rotatable body forms a transfer nip with the image bearer to rotate in contact with a recording medium. An image on the image bearer is transferred onto the recording medium at the transfer nip. The solid lubricant assembly includes a solid lubricant and extends in a longitudinal direction of the rotatable body. The solid lubricant assembly applies a solid lubricant to at least one of the rotatable body and the image bearer. The guide guides the recording medium and positions the solid lubricant assembly.

Abstract: An image forming apparatus including an image bearer; a nip forming member, a nip width changing device, a power source; and a controller. The controller switches between a first mode and a second mode according to a predetermined condition. In the first mode, a duty of the transfer bias is a first duty and a width of a transfer nip is a first width. In the second mode, the duty of the transfer bias is a second duty lower than the first duty and the width of the transfer nip is a second width greater than the first width. The duty is (T?Tt)/T×100% where T denotes one cycle of the transfer bias, and Tt denotes a time period, in which the transfer bias is on a transfer-directional side relative to a time-averaged value of the transfer bias, in the one cycle.

Abstract: An image forming apparatus includes an image bearer, an image forming device to form a toner image on the image bearer with toner, a power source to output a bias to transfer the toner image onto a recording medium, and control circuitry. The circuitry controls the power source to decrease a peak-to-peak voltage of the bias in response to increase in at least one of temperature and humidity, when a time-averaged voltage of the bias is on a transfer side of transferring the toner to the recording medium, from a median value of maximum and minimum voltages of the bias. The circuitry controls the power source to increase the peak-to-peak voltage of the bias in response to increase in at least one of temperature and humidity, when the time-averaged voltage of the bias is on a return side of returning the toner to the image bearer, from the median value.

Abstract: An image forming apparatus includes a transfer power supply and a controller. The controller is configured to execute control for an end-portion voltage that is a DC voltage of a transfer bias at a time of transferring a toner image to an end portion of a recording sheet and a body-portion voltage that is a DC voltage of a transfer bias at a time of transferring a toner image to a body portion on a rear side of an end portion of a recording sheet, such that the end-portion voltage is set to be higher than the body-portion voltage in the DC transfer bias and a value obtained by dividing the end-portion voltage by the body-portion voltage in the superimposed transfer bias is set to be smaller than a value obtained by dividing the end-portion voltage by the body-portion voltage in the DC transfer bias.

Abstract: A transfer device includes an image bearer, a rotatable body, a solid lubricant assembly, and a guide. An image bearer bears an image. The rotatable body forms a transfer nip with the image bearer to rotate in contact with a recording medium. An image on the image bearer is transferred onto the recording medium at the transfer nip. The solid lubricant assembly includes a solid lubricant and extends in a longitudinal direction of the rotatable body. The solid lubricant assembly applies a solid lubricant to at least one of the rotatable body and the image bearer. The guide guides the recording medium and positions the solid lubricant assembly.

Abstract: An image forming apparatus includes a developing device, an image bearer, a transfer rotator, a blade contacting a surface of the transfer rotator, and a controller to control the developing device, the image bearer, and the transfer rotator. A first toner pattern image is formed on the image bearer, transferred onto the transfer rotator, and passed past the blade at least twice together with rotation of the transfer rotator in at start-up of the image forming apparatus. A second toner pattern image is formed on the image bearer after the start-up and during passage of a non-image area in which toner images are not formed. A range of the first toner pattern image is wider than a range of the second toner pattern image in a width direction perpendicular to a direction of travel of the image bearer.

Abstract: An image forming apparatus includes an image bearer; a toner image forming device; an intermediate transferor; a primary transfer power source; a secondary transfer nip forming device; and a secondary transfer power source to output a secondary transfer bias. One of two peak values of the secondary transfer bias is a transfer peak value to provide a greater transfer-directional force to move toner from the intermediate transferor toward the recording medium in the secondary transfer nip. An absolute value of the transfer peak value is greater than an absolute value of the primary transfer bias.

Abstract: An image forming apparatus includes a plurality of image bearers, a transfer bias member, and a power source. When the transfer bias member transfers a color toner image onto a recording sheet, a second peak value of a peak-to-peak of a transfer bias, which is smaller than a first peak value of the peak-to-peak in an electrostatic force to move toner from the image bearers or an intermediate transfer body to the recording sheet, is zero or has a first polarity to generate the electrostatic force in a transfer direction to move toner from the image bearers or the intermediate transfer body to the recording sheet. When the transfer bias member transfers a monochromatic toner image including only black toner onto the recording sheet, the second peak value is zero or has a second polarity to generate an electrostatic force in an opposite direction to the transfer direction.

Abstract: An image forming apparatus includes a rotatable image bearer, a toner image forming device, a transfer device, a transfer bias power source, and a cleaner. The toner image forming device is to form a toner image on the image bearer. The transfer device contacts a surface of the image bearer to form a transfer nip between the transfer device and the image bearer. The transfer bias power source is to output a transfer bias to transfer the toner image from the image bearer onto a recording medium in the transfer nip. The cleaner is disposed downstream from the transfer nip in a direction of rotation of the image bearer, to electrostatically attract and remove toner from the surface of the image bearer to a surface of the cleaner. The transfer bias includes an alternating current component.

Abstract: An image forming apparatus including an image bearer, a transfer-bias power source, an environment sensor, and a controller. The controller controls the transfer-bias power source to change the DC component and the AC component, according to the at least one of temperature and humidity detected by the environment sensor and a duty of the transfer bias. The duty is A/(A+B)×100[%] where A denotes an area on a return-directional side to move toner from the recording sheet back to the image bearer, relative to a center value (Voff) of a maximum value and a minimum value of the transfer bias in one cycle of a waveform of the transfer bias, and B denotes an area on a transfer-directional side to move the toner from the image bearer to the recording sheet, relative to the center value (Voff) in the one cycle.

Abstract: An image forming apparatus includes an image bearer, an image forming device to form a toner image on the image bearer with toner, a power source to output a bias to transfer the toner image onto a recording medium, and control circuitry. The circuitry controls the power source to decrease a peak-to-peak voltage of the bias in response to increase in at least one of temperature and humidity, when a time-averaged voltage of the bias is on a transfer side of transferring the toner to the recording medium, from a median value of maximum and minimum voltages of the bias. The circuitry controls the power source to increase the peak-to-peak voltage of the bias in response to increase in at least one of temperature and humidity, when the time-averaged voltage of the bias is on a return side of returning the toner to the image bearer, from the median value.

Abstract: An image forming apparatus including an image bearer; a nip forming member, a nip width changing device, a power source; and a controller. The controller switches between a first mode and a second mode according to a predetermined condition. In the first mode, a duty of the transfer bias is a first duty and a width of a transfer nip is a first width. In the second mode, the duty of the transfer bias is a second duty lower than the first duty and the width of the transfer nip is a second width greater than the first width. The duty is (T?Tt)/T×100% where T denotes one cycle of the transfer bias, and Tt denotes a time period, in which the transfer bias is on a transfer-directional side relative to a time-averaged value of the transfer bias, in the one cycle.

Abstract: An image forming apparatus, including an image bearer configured to bear a toner image; a transfer device disposed opposing to the image bearer; and a transfer bias power source. The transfer bias power source is configured to output a transfer bias to transfer the toner image onto a recording medium. The transfer bias is a superimposed bias that cyclically alternates between a transfer-directional bias to transfer the toner image from the image bearer onto the recording medium and an opposite-directional bias in an opposite direction of the transfer direction. A ratio of a time period of application of the opposite-directional bias to a total time period of one cycle of the output transfer bias is greater than 50%. The transfer bias power source changes a value of a direct current voltage in the superimposed bias according to a linear velocity of the image bearer.

Abstract: An image forming apparatus includes a belt-shaped image bearer, a transferer, a guide, two rotators, and a support. The image bearer has an image bearing surface to bear an image thereon. The transferer forms a transfer section between the transferer and the image hearer, to transfer the image onto a recording medium. The guide is disposed upstream from the transfer section in a delivery direction of the recording medium, to guide the recording medium toward the transfer section. The two rotators are disposed upstream from the transfer section in a moving direction of the image bearer and in contact with a non-image bearing surface of the image bearer opposite to the image bearing surface, a first rotator being closer to the transfer section than a second rotator. The support supports the first rotator and the guide and adjusts a position of the first rotator and a position of the guide.

Abstract: An image forming apparatus includes a toner image forming unit, a nip formation member, a transfer power source, an information acquisition device, and a controller. The information acquisition device acquires specific information that specifies whether a recording sheet as a transfer target of a toner image is an uneven surface sheet having an uneven surface. The controller outputs a bias including a superimposed voltage, in which an alternating current (AC) voltage is superimposed on a direct current (DC) voltage, as a transfer bias from the transfer power source when the specific information acquired by the information acquisition device is not information corresponding to the uneven surface sheet and to output a bias including only the DC voltage as the transfer bias from the transfer power source when the specific information is the information corresponding to the uneven surface sheet.

Abstract: An improved image forming apparatus includes an image bearer, a nip forming member, a transfer power source, and a controller. The controller switches a transfer mode between a first mode to transfer the toner image onto a first type sheet having a surface smoothness higher than a surface smoothness of a second type sheet and a second mode to transfer the toner image onto the second type sheet. The controller controls the transfer power source to output the transfer bias having an opposite-peak duty of greater than or equal to 50% that is a duty on the side of the opposite-peak value in the first mode. The controller controls the transfer power source to output the transfer bias having an opposite-peak duty of less than 50%, which is different from the opposite-peak duty of the first mode, in the second mode.