An electrostatic printer comprises a charging unit, a photoconductor member, an imaging unit, a developer unit and a controller. The charging unit is to charge the photoconductor member to a charged voltage. The imaging unit is to generate a latent electrostatic image on the photoconductor member by discharging areas of the charged photoconductor member. The developer unit is to develop a toner image on the photoconductor member using a developer voltage. The controller is to change the developer voltage, and to change the charged voltage dependent on the change of the developer voltage.

An image forming apparatus includes a tray which is movable between a housed position at which the tray is housed in a housing portion of a body and a drawn-out position, a first cartridge detachably attached to the tray and including a first developing roller, and a second cartridge detachably attached to the tray and including a second developing roller. In a contacting state where (i) the first cartridge and the second cartridge are attached to the tray, (ii) the tray is in the housed position, (iii) the first developing roller contacts a first photosensitive drum, and (iv) the second developing roller contacts a second photosensitive drum, a position of a first projection of the first cartridge and a position of a first holder to which a first memory is fixed at least partially overlap each other with respect to the vertical direction.

An image forming apparatus includes an image bearing drum; a drum charging member at a charging position opposed to the drum, with a charging bias; a developing member for developing an electrostatic image formed on the drum with toner, with a developing bias; a transfer member for transferring a toner image from the drum onto a sheet, with a transfer bias; a transfer bias source for outputting transfer bias; and a controller for effecting control to start raising of the transfer bias so as to correspond to timing at which an area of the drum passing at a timing of starting of raising of the charging bias passes the transfer position and to complete the raising of the transfer bias so as to correspond to timing at which an area of the drum passing at a timing of completion of raising of the charging bias passes the transfer position.

A light scanning apparatus, including: a light source configured to emit a light beam; a light intensity detection portion configured to detect a light intensity of the light beam; and a light intensity control portion configured to control the light intensity of the light beam based on a detection result of the light intensity detection portion, wherein the light intensity control portion supplies, in advance, to the light source, a bias current equal to or less than a threshold current at which the light source starts emitting the light beam, and supplies, to the light source, a switching current superposed on the bias current, the switching current being modulated in order to control light emission of the light source in accordance with an image signal, and wherein the light intensity control portion includes a bias current changing unit configured to change the bias current.

An image forming apparatus that includes an image bearing member which can bear a toner image, a transfer member used to transfer a toner image onto a recording material from the image bearing member, and a reading device which reads density information of images on recording material disposed on a platen. The image forming apparatus forms a first chart on a first recording material and a second chart on a second recording material by sequentially transferring a plurality of test images while applying a plurality of test voltages to the transfer member. The two charts are read by the reading device and the transfer voltage is adjusted based on the reading result.

At least one partial measurement region is set in the longitudinal direction in a printable region of a photosensitive drum 3. After the photosensitive drum 3 has been charged to a constant potential with a charging roller 6, different potentials are set in the partial measurement region and a region excluding partial measurement region with a laser scanner 4, partial discharge information of the partial measurement region is detected by discharge information detection unit, and a bias voltage in image formation that is applied to the charging roller 6 is corrected on the basis of the value of the partial discharge information.

An image forming apparatus includes a photoconductor, a charger, a detection unit, and a determination unit. The charger charges the photoconductor. The detection unit detects an actual charging potential of the photoconductor after the photoconductor is charged by the charger. The determination unit determines one of a plurality of causes related to a charging abnormality of the photoconductor based on a relationship between a standard charging potential of the photoconductor to be obtained by charging by the charger and a charging potential detected by the detection unit.

In a configuration in which a voltage of polarity opposite to charging polarity of toner is applied to a conveyance guide, controlling deposition of toner on the conveyance guide has been difficult. When performing duplex image formation, a potential difference between a surface potential of a photoconductive drum charged by a charging roller and a potential of the conveyance guide is smaller during printing on the second surface than during printing on the first surface.

An exposing unit forms a latent-image electric potential on each photosensitive drum. A detecting toner image of each color is transferred to an intermediate transfer belt using a first potential difference between a latent-image electric potential and the potential of an intermediate transfer belt at each primary transfer portion. When the polarity of voltage to be applied from a transfer power source to a secondary transfer roller is to be switched to an opposite polarity while the detecting toner image of each color is passing through each primary transfer portion, the absolute value of a second potential difference between the potential of the intermediate transfer belt and the background electrical potential of each photosensitive drum is made equal to or greater than the absolute value of the first potential difference by a control unit.

An image forming apparatus includes a first image bearing member, a second image bearing member, an intermediate transfer belt, a first primary transfer member, a second primary transfer member, a secondary transfer outer member, a pre-secondary transfer stretch roller, a driving roller, and an execution portion. The execution portion is configured to execute a first monochromatic mode in which a bias smaller than the primary transfer bias applied to the first primary transfer member in a case where a toner image is formed on the first image bearing member is applied to the first primary transfer member, and the primary transfer bias applied to the second primary transfer member in a case where a toner image is formed on the second image bearing member is applied to the second primary transfer member.