A control portion can perform an image formation mode to perform image formation while controlling, based on the relationship between a charging current and the surface potential on an image carrying member, a charging voltage and thereby adjusting the surface potential and a correction mode to correct the relationship between the charging current and the surface potential. In the correction mode, the control portion calculates the surface potential on the image carrying member based on the developing voltage applied and the developing current sensed by a developing current sensing portion and corrects the relationship between the charging current and the surface potential based on the calculated surface potential.

An image forming apparatus includes a bearer, a charger charging the bearer at a charging position, a developing device forming an image at a developing position, a transferor transferring the image onto a transfer medium in a transfer period, a power source to flow a first current during the transfer period and a second current during a non-transfer period, and circuitry. The circuitry controls the power source to set a value of the second current to at least one of zero or a value having the same polarity as the first current and an absolute value different from that of the first current and set a charge amount of toner on the bearer between the charging position and the developing position to be from 30 C/g to 25 C/g.

A driving control apparatus includes a movable member that can be displaced between first and second positions, a solenoid that displaces the movable member at the first position to the second position, a control unit that controls supply of current to the solenoid, and a transmission mechanism that transitions between first and second states according to a position of the movable member. The transmission mechanism transmits a driving force to a driven member in one of the first and second states. When the solenoid displaces the movable member from the first position to the second position, the current is supplied to the solenoid at a first duty cycle in a first period and is supplied to the solenoid at a second duty cycle lower than the first duty cycle in a subsequent second period.

An image forming apparatus includes four photosensitive members, a first optical scanning unit, a second optical scanning unit, a first detection unit, a second detection unit and a control unit. The first optical scanning unit draws a first reference image and a first opposite image. The second optical scanning unit draws a second reference image and draws a second opposite image. The first detection unit detects the internal temperature of at least one of the first optical scanning unit and the second optical scanning unit. The second detection unit detects an apparatus internal temperature within an apparatus main body. The control unit corrects positions of the drawing of the first opposite image, the drawing of the second reference image and the drawing of the second opposite image based on the amount of change in the internal temperature and the amount of change in the apparatus internal temperature.

An image formation system includes an image carrier that rotates; an opposed member that is opposed to the image carrier and is connected to the image carrier by an adjuster that adjusts a distance to the image carrier; and a temperature detector that is provided on any two or more components among the opposed member, the adjuster, and components other than the adjustor that are interposed between the opposed member and the image carrier.

An image forming apparatus includes an image forming portion, an exposure device, an image density sensor, and a control portion. The control portion can, by adjusting the development voltage based on the image density of a reference image and the amount of exposure from the exposure device, perform image density correction to adjust the image density. The control portion predicts the toner charge amount based on a formation condition of the reference image and the image density of the reference image and determines the timing of performing the image density correction next time based on the rate of change of the toner charge amount calculated using a first toner charge amount predicted when the image density correction was performed last time, a second toner charge amount predicted when the image density correction is performed this time, and the interval between the image density correction performed last time and this time.

PROBLEM TO BE SOLVED: To provide an image forming apparatus that can effectively reduce the occurrence of image failure and generation of a discharge product by correcting a charge voltage according to a change in electrical characteristic of a photosensitive layer on a surface of an image carrier.

SOLUTION: An image forming apparatus comprises: an image carrier on a surface of which a photosensitive layer is formed; a charging device that charges the surface of the image carrier; a voltage application device; a temperature and humidity detection device; a time measuring unit; and a control unit. The voltage application device applies a charge voltage to the charging device. The temperature and humidity detection device detects the temperature and humidity around the image carrier. The time measuring unit measures a low-humidity environment standing time during which the image carrier is continuously in a non-driving state while the humidity detected by the temperature and humidity detection device is equal to or less than a predetermined value, and when the humidity detected by the temperature and humidity detection device exceeds the predetermined value, resets the low temperature environment standing time. The control unit sets the amount of correction of the charge voltage on the basis of the temperature and humidity detected by the temperature and humidity detection device, and changes the amount of correction of the charging voltage on the basis of the low-humidity environment standing time.

An image forming apparatus according to the present disclosure includes: an image forming portion configured to apply a bias voltage between a first carrier with a surface to be charged and a second carrier configured to hold toner to be adhered to the first carrier to move the toner from the second carrier to a developing area of the first carrier to develop the developing area of the first carrier; a current detection portion configured to detect a target current that flows between the first carrier and the second carrier during development; a temperature detection portion configured to detect a temperature inside the apparatus; and a cooling control portion configured to execute a predetermined cooling operation based on a detected current that is detected by the current detection portion and a detected temperature that is detected by the temperature detection portion.

An image forming apparatus includes an image bearing member, a transfer member, an acquiring portion, an applying portion, and a controller. When a transfer voltage is subjected to constant-voltage control so that the transfer voltage applied to the transfer member by the applying portion is substantially constant, in a case that the transfer voltage, when a toner amount used for a toner image is a first toner amount, is a first voltage, the controller controls the applying portion so that the transfer voltage is a second voltage lower in absolute value than the first voltage in a case that the toner amount is a second toner amount greater than the first toner amount. The acquiring portion acquires toner amount information on the toner amount for each toner image transferred onto a single recording material.

An image forming apparatus includes an image bearing member, a transfer member, an acquiring portion, an applying portion, and a controller. When a transfer voltage is subjected to constant-voltage control so that the transfer voltage applied to the transfer member by the applying portion is substantially constant, in a case that the transfer voltage, when a toner amount used for a toner image is a first toner amount, is a first voltage, the controller controls the applying portion so that the transfer voltage is a second voltage lower in absolute value than the first voltage in a case that the toner amount is a second toner amount greater than the first toner amount. The acquiring portion acquires toner amount information on the toner amount for each toner image transferred onto a single recording material.