Abstract: An image forming apparatus includes an image bearer, a transfer member, and a power source. The image bearer includes a plurality of layers. The transfer member forms a transfer nip between the image bearer and the transfer member. The power source outputs a transfer bias to transfer a toner image from the image bearer onto a recording sheet in the transfer nip. The transfer bias alternates between a transfer-side bias that causes the toner image to move from the image bearer to the recording sheet, and an opposite-side bias different from the transfer-side bias. A duty ratio of a time period, during which the opposite-side bias is output, relative to one cycle of a waveform, is greater than 50%.

Abstract: An image forming apparatus includes an image bearer, a toner image forming device, a nip forming device, a power source, a controller, and a temperature-and-humidity detector. The toner image forming device forms a toner image on the image bearer. The nip forming device contacts the image bearer to form a transfer nip. The power source outputs a transfer bias, in which an alternating current component is superimposed on a direct current component, to transfer the toner image onto a recording medium interposed in the transfer nip. The temperature-and-humidity detector detects a temperature and humidity. The controller controls the power source to output the transfer bias including the direct current component with a smaller absolute value as at least one of the detected temperature and humidity increases.

Abstract: An image forming apparatus includes an image bearer, a transfer member, and a power source. The image bearer includes a plurality of layers. The transfer member forms a transfer nip between the image bearer and the transfer member. The power source outputs a transfer bias to transfer a toner image from the image bearer onto a recording sheet in the transfer nip. The transfer bias alternates between a transfer-side bias that causes the toner image to move from the image bearer to the recording sheet, and an opposite-side bias different from the transfer-side bias. A duty ratio of a time period, during which the opposite-side bias is output, relative to one cycle of a waveform, is greater than 50%.

Abstract: An image forming apparatus includes an image bearer, a transfer member, and a power source. The image bearer includes a plurality of layers. The transfer member forms a transfer nip between the image bearer and the transfer member. The power source outputs a transfer bias to transfer a toner image from the image bearer onto a recording sheet in the transfer nip. The transfer bias alternates between a transfer-side bias that causes the toner image to move from the image bearer to the recording sheet, and an opposite-side bias different from the transfer-side bias. A duty ratio of a time period, during which the opposite-side bias is output, relative to one cycle of a waveform, is greater than 50%.

Abstract: An image forming apparatus includes an image bearer, a toner image forming device, a nip forming device, a power source, a controller, and a temperature-and-humidity detector. The toner image forming device forms a toner image on the image bearer. The nip forming device contacts the image bearer to form a transfer nip. The power source outputs a transfer bias, in which an alternating current component is superimposed on a direct current component, to transfer the toner image onto a recording medium interposed in the transfer nip. The temperature-and-humidity detector detects a temperature and humidity. The controller controls the power source to output the transfer bias including the direct current component with a smaller absolute value as at least one of the detected temperature and humidity increases.

Abstract: An image forming apparatus includes an image bearer, a transfer member, and a power source. The image bearer includes a plurality of layers. The transfer member forms a transfer nip between the image bearer and the transfer member. The power source outputs a transfer bias to transfer a toner image from the image bearer onto a recording sheet in the transfer nip. The transfer bias alternates between a transfer-side bias that causes the toner image to move from the image bearer to the recording sheet, and an opposite-side bias different from the transfer-side bias. A duty ratio of a time period, during which the opposite-side bias is output, relative to one cycle of a waveform, is greater than 50%.

Abstract: An image forming apparatus includes a toner image carrying member, an image transfer device, a fixing device, a registration unit, a guide member, an upstream-side transportation unit, and a downstream-side transportation unit. The image transfer device transfers a toner image from the toner image carrying member to a recording medium. The fixing device fixes the toner image. The registration unit transports the recording medium. The guide member guides the recording medium. The upstream-side transportation unit includes an upstream-side transportation member, disposed at an upstream side in the transport direction of the recording medium. The downstream-side transportation unit includes the downstream-side transportation member, disposed at a downstream side in the transport direction of the recording medium. The upstream-side transportation unit includes an upstream-side positioning member to position the guide member to the upstream-side transportation member.

Abstract: An image forming apparatus includes an intermediate transfer belt, a photosensitive belt, a primary transfer roller, a secondary-transfer opposing roller, and a secondary transfer roller. The photosensitive belt comes into contact with a surface of the intermediate transfer belt to form a primary transfer nip. The secondary-transfer opposing roller comes into contact with the surface of the intermediate transfer belt to form a secondary transfer nip. The closest distance between a surface of the photosensitive belt and that of the primary transfer roller is greater than the thickness of the intermediate transfer belt. A toner image on the intermediate transfer belt is transferred onto a recording sheet at the secondary transfer nip while a transfer bias is applied to the secondary transfer roller.

Abstract: A transfer device, which transfers an image onto a recording medium directly or indirectly and is included in an image forming apparatus, includes an endless belt member extended between a drive roller rotated and a driven roller and configured to receive the image from the image carrier part onto either a surface thereof or the recording medium carried on the surface thereof while moving according to rotations of the drive roller, and a rotation speed detector configured to detect a rotation speed of the driven roller. An image detector is provided either to the transfer device or to the image forming apparatus to detect the image formed on the endless belt member directly or the recording medium carried on the endless belt member, and disposed facing the driven roller in a circumferential direction of the endless belt member.

Abstract: An image forming apparatus includes an intermediate transfer belt, a photosensitive belt, a primary transfer roller, a secondary-transfer opposing roller, and a secondary transfer roller. The photosensitive belt comes into contact with a surface of the intermediate transfer belt to form a primary transfer nip. The secondary-transfer opposing roller comes into contact with the surface of the intermediate transfer roller to form a secondary transfer nip. The closest distance between a surface of the photosensitive belt and that of the primary transfer roller is greater than the thickness of the intermediate transfer belt. A toner image on the intermediate transfer belt is transferred onto a recording sheet at the secondary transfer nip while a transfer bias is applied to the secondary transfer roller.

Abstract: An image forming apparatus includes an intermediate transfer belt, a photosensitive belt, a primary transfer roller, a secondary-transfer opposing roller, and a secondary transfer roller. The photosensitive belt comes into contact with a surface of the intermediate transfer belt to form a primary transfer nip. The secondary-transfer opposing roller comes into contact with the surface of the intermediate transfer belt to form a secondary transfer nip. The closest distance between a surface of the photosensitive belt and that of the primary transfer roller is greater than the thickness of the intermediate transfer belt. A toner image on the intermediate transfer belt is transferred onto a recording sheet at the secondary transfer nip while a transfer bias is applied to the secondary transfer roller.

Abstract: A belt member faces a plurality of carrying bodies that respectively carry toner images or developers. A plurality of facing members respectively faces the carrying bodies via the belt member. A detaching unit brings at least one of the facing members to face a corresponding carrying body and detaches other facing members from other carrying bodies. A contacting member contacts the belt member to detach the belt member from the other carrying bodies when the detaching unit detaches the other facing members from the other carrying bodies.

Abstract: An image forming apparatus includes a toner image carrying member, an image transfer device, a fixing device, a registration unit, a guide member, an upstream-side transportation unit, and a downstream-side transportation unit. The image transfer device transfers a toner image from the toner image carrying member to a recording medium. The fixing device fixes the toner image. The registration unit transports the recording medium. The guide member guides the recording medium. The upstream-side transportation unit includes an upstream-side transportation member, disposed at an upstream side in the transport direction of the recording medium. The downstream-side transportation unit includes the downstream-side transportation member, disposed at a downstream side in the transport direction of the recording medium. The upstream-side transportation unit includes an upstream-side positioning member to position the guide member to the upstream-side transportation member.

Abstract: An optical sensor detects at least one of a toner image and a toner adhesion amount per unit area based on a change of an optical characteristic on a surface of an endless belt member. A control unit performs a predetermined process based on a detection result obtained by the optical sensor. A sensor moving unit moves the optical sensor between a first position in opposite to a belt supporting area in which the endless belt member is supported by a supporting roller and a second position that is different from the first position. The detection result is obtained by the optical sensor when the optical sensor is placed at the first position by the sensor moving unit.

Abstract: A transfer device, which transfers an image onto a recording medium directly or indirectly and is included in an image forming apparatus, includes an endless belt member extended between a drive roller rotated and a driven roller and configured to receive the image from the image carrier part onto either a surface thereof or the recording medium carried on the surface thereof while moving according to rotations of the drive roller, and a rotation speed detector configured to detect a rotation speed of the driven roller. An image detector is provided either to the transfer device or to the image forming apparatus to detect the image formed on the endless belt member directly or the recording medium carried on the endless belt member, and disposed facing the driven roller in a circumferential direction of the endless belt member.

Abstract: An optical sensor detects at least one of a toner image and a toner adhesion amount per unit area based on a change of an optical characteristic on a surface of an endless belt member. A control unit performs a predetermined process based on a detection result obtained by the optical sensor. A sensor moving unit moves the optical sensor between a first position in opposite to a belt supporting area in which the endless belt member is supported by a supporting roller and a second position that is different from the first position. The detection result is obtained by the optical sensor when the optical sensor is placed at the first position by the sensor moving unit.

Abstract: An image forming apparatus includes an intermediate transfer belt, a photosensitive belt, a primary transfer roller, a secondary-transfer opposing roller, and a secondary transfer roller, The photosensitive belt comes into contact with a surface of the intermediate transfer belt to form a primary transfer nip. The secondary-transfer opposing roller comes into contact with the surface of the intermediate transfer roller to form a secondary transfer nip. The closest distance between a surface of the photosensitive belt and that of the primary transfer roller is greater than the thickness of the intermediate transfer belt. A toner image on the intermediate transfer belt is transferred onto a recording sheet at the secondary transfer nip while a transfer bias is applied to the secondary transfer roller.

Abstract: A belt member faces a plurality of carrying bodies that respectively carry toner images or developers. A plurality of facing members respectively faces the carrying bodies via the belt member. A detaching unit brings at least one of the facing members to face a corresponding carrying body and detaches other facing members from other carrying bodies. A contacting member contacts the belt member to detach the belt member from the other carrying bodies when the detaching unit detaches the other facing members from the other carrying bodies.

Abstract: An image-forming apparatus includes an image-bearing device that holds an electrostatic latent image and a toner image thereon, and a developer container that contains and agitates a developer having at least a toner. The image-forming apparatus also includes a developer-bearing device that carries the developer to develop the electrostatic latent image on the image-bearing device, and a density sensor that detects an optical density of a surface of the image-bearing device and a toner image on the image-bearing device. Further, the image-forming apparatus includes a developer seal that seals the developer in the developer container, wherein the seal is disposed between the developer container and the developer-bearing device, and an actuator configured to actuate the developer container and the developer-bearing device.

Abstract: An image forming apparatus includes an image carrier and a developing device to develop a latent image formed on the image carrier by applying two-component developer, including toner, onto the latent image. The developing device includes a developing part containing the two-component developer and a developer stirring device to stir the two-component developer. A toner supplying device supplies toner to the developing part of the developing device, and a toner density detection device detects a toner density of the two-component developer in the developing device. A toner control device calculates a difference between an output value VT of the toner density detection device and a criterion value VTref for controlling the toner density of the two-component developer and controls the toner supplying device based upon the difference.