A printing apparatus includes a voltage supply section that supplies a charging voltage for charging a transport belt, a detection section that detects whether or not charging abnormality has occurred in the transport belt, and a determination section that determines a cause of the charging abnormality. The determination section determines that the cause of the charging abnormality is abnormality of the voltage supply section, when the movement period includes the period for which the detection section detects the charging abnormality and does not include the period for which the detection section does not detect the charging abnormality.

An image forming apparatus includes an image forming portion, an image bearing member, a transfer member, a voltage applying portion, a detecting portion, and a controller capable of executing an operation in an adjustment mode in which a chart on which a plurality of test images are transferred by stepwise changing a test voltage applied to the transfer member by the applying portion is formed on a recording material and then a transfer voltage applied to the transfer member applied by the voltage applying portion during transfer of the toner image is adjusted. The controller is capable of changing a change width per level of the test voltage applied during formation of the chart, on the basis of a detection result of the detecting portion when the voltage is applied to the transfer member when the recording material on which the chart is formed is in the transfer portion.

A printing apparatus includes a printing section that performs printing on a medium containing calcium carbonate, a transport section that rotationally drives a transport belt that forms at least a portion of a transport path in which the medium is transported, a voltage supply section that supplies a charging voltage to a charging roller for charging the transport belt, a detection section that detects whether or not charging abnormality has occurred in the transport belt, and a determination section that determines whether abnormality has occurred in the voltage supply section or the transport belt, or abnormality has occurred in the voltage supply section and the transport belt, based on a rotation amount of the transport belt and the detection result of the detection section. The transport belt is coated with melamine resin.

An image forming apparatus includes a photosensitive drum, a charging roller, a development device, a transfer roller, a first electricity eliminator and a controller. The photosensitive drum is provided on a conveyance path along which a sheet is conveyed. The charging roller charges the photosensitive drum. The development device develops an electrostatic latent image formed on the photosensitive drum charged by the charging roller. The transfer roller faces the photosensitive drum across the conveyance path and generates a transfer bias. The first electricity eliminator irradiates the photosensitive drum with light on a downstream side of the development device in a rotational direction of the photosensitive drum and on an upstream side of the transfer roller in the rotational direction. The controller which controls the first electricity eliminator so as to irradiate only a non-sheet passing area of the photosensitive drum with the light.

An image forming apparatus includes an image carrier that carries a toner image; a transfer part that is disposed so as to be in contact with the image carrier and transfers the toner image carried by the image carrier to a recording medium; and a charge applying part that is disposed on an upstream side of the transfer part in a recording-medium transport direction and charges the recording medium such that an amount of charge in the recording medium varies according to the position therein in a direction intersecting a recording-medium transport direction when the recording medium has reached the transfer part.

A controller is configured to execute a larger gamut technology mode in which the controller performs image formation by controlling a ratio of a rotation speed of a development roller to a rotation speed of a photosensitive drum such that the ratio becomes a second speed ratio higher than a first speed ratio in a normal mode. The controller is configured to, when the controller executes the larger gamut technology mode, control transfer voltage based on a humidity around an image forming apparatus.

An image formation apparatus includes: a process device that forms a developer image; a transfer device that transfers the developer image formed by the process device onto a recording medium; a voltage applier that applies a voltage to the transfer device; and a voltage controller that acquires information on a width of the recording medium in a direction orthogonal to a medium conveyance direction, and controls the voltage applied by the voltage applier to the transfer device based on the width of the recording medium.

A transfer apparatus includes a transfer unit, a first detector, a supplying unit, a second detector, and a controller. The transfer unit transfers a toner image onto an object. The first detector detects humidity. The supplying unit supplies, to the transfer unit, a transfer voltage, a setting voltage in a first case, and a setting current in a second case. The second detector detects a current flowing through the transfer unit upon supply of the setting voltage and a voltage across the transfer unit upon supply of the setting current. The controller controls the supplying unit such that, when transfer is performed in the first case, a transfer voltage derived using the setting voltage and the detected current is supplied, and when transfer is performed in the second case, a transfer voltage derived using the setting current and the detected voltage is supplied to the transfer unit.

An image forming apparatus includes an image bearer including a first image portion to bear a first toner image, a second image portion to bear a second toner image, and a non-image portion to bear an adjustment pattern. A transferor forms a transfer nip with the image bearer. A controller controls the power source to output an image bias as a transfer bias to transfer the first toner image and the second toner image onto a first recording medium and a second recording medium, respectively, in the transfer nip when the first image portion and the second image portion pass through the transfer nip and output a non-image bias as the transfer bias when the non-image portion passes through the transfer nip. The controller performs a constant current control on the image bias and performs a constant voltage control when the image bias switches to the non-image bias.

A voltage maintenance element is connected to a contact member that contacts a primary transfer surface area of an intermediate transfer belt to which toner images are transferred from a plurality of image carriers between stretch members, in such a way as to prevent the electric potential of the intermediate transfer belt from varying between respective image forming stations.