After a predetermined period elapses since the start of use of a photosensitive member, if a calculated value calculated from a detection current between a charging unit and a photosensitive member is out of a predetermined range, a determining unit does not perform determination using a currently calculated value and, if the calculated value is within the predetermined range, the determining unit performs determination using the currently calculated value.

An image forming apparatus includes a plurality of image bearers, an intermediate transferor, a plurality of primary transferors, a primary transfer power source, a primary transfer current detector, and processing circuitry. The primary transferors primarily transfer toner images of colors from the image bearers onto the intermediate transferor. The intermediate transferor secondarily transfers the toner images onto a transfer medium. The primary transfer power source applies voltage to the primary transferors. The primary transfer current detector detects a current flowing through the primary transferors when a specified voltage is applied to the primary transferors and is connected to only one primary transferor of one color among all the colors. The processing circuitry determines a primary transfer voltage based on a current value detected by the primary transfer current detector and determines a primary transfer voltage value of the primary transferors of all the colors based on the detected current value.

An image forming apparatus comprises a transferer transferring a toner image on an image carrier onto a sheet, and facing the image carrier; a fixer fixing the toner image on the sheet; and a controller applying transfer voltage for transferring the toner image onto the sheet, wherein the transferer defines a transfer nip for passing the sheet between the image carrier and the transferer, the fixer includes a heating portion and a pressing portion, and passes the sheet after passing through the transfer nip through a fixing nip between the heating portion and the pressing portion, and the controller controls the transfer voltage in such a way that transfer current flowing through the transfer nip is made constant at a setting value, and increases the setting value of transfer current after a leading end of the sheet passes through the transfer nip and before it passes through the fixing nip.

An imaging device has a developer roll to provide toner to a photoconductive drum to develop a latent image on the drum for direct transfer to media or an intermediate transfer member. A power supply in communication with a controller sets relative voltages on the developer roll and drum. During transfer of the toner, the imaging device determines a current between the developer roll and drum. In turn, the controller determines a charge and mass of the toner for setting with the power supply an operating voltage on the drum or developer roll. Preventing and reporting toners with insufficient charge are other embodiments.

A charge-eliminating apparatus includes a charge-eliminating member for eliminating charge of a sheet while nipping and conveying the sheet, a voltage applying unit for applying a voltage to the charge-eliminating member, and a detecting unit for detecting a voltage applied to the charge-eliminating member or a current flowing through the charge-eliminating member. A controller measures an electrification charge amount of the sheet based on a detecting result of the detecting unit while the sheet passes through the charge-eliminating member.

A charge-eliminating apparatus configured to perform charge elimination on a sheet includes a charge-eliminating member configured to perform charge elimination on the sheet, a power source configured to apply a voltage to the charge-eliminating member, a contacting member configured to be brought into contact with the sheet, a detection circuit configured to detect a voltage applied to the contacting member or a current flowing in the contacting member, and a controlling unit configured to control the power source, wherein the controlling unit determines a value of the voltage applied from the power source to the charge-eliminating member during charge elimination by the charge-eliminating member based on a detection result from the detection circuit during passage of the sheet along the contacting member, and wherein the voltage applied to the contacting member undergoes constant current control, and the voltage applied to the charge-eliminating member undergoes constant voltage control.

An imaging device has a developer roll to provide toner to a photoconductive drum to develop a latent image on the drum for direct transfer to media or an intermediate transfer member. A power supply in communication with a controller sets relative voltages on the developer roll and drum. During transfer of the toner, the imaging device determines a current between the developer roll and drum. In turn, the controller determines a charge and mass of the toner for setting with the power supply an operating voltage on the drum or developer roll. Preventing and reporting toners with insufficient charge are other embodiments.

A method of controlling a printing system including a printing apparatus that prints an image on a sheet and a charge eliminating apparatus that performs a charge eliminating process on the sheet on which the image is printed includes measuring an amount of charge on the sheet that has undergone the charge eliminating process performed by the charge eliminating apparatus, and displaying a message prompting a user to change a setting for charge elimination to be performed by the charge eliminating apparatus in a case where the amount of charge on the sheet measured in the measuring does not fall within a predetermined range.

A method of controlling a printing system including a printing apparatus that prints an image on a sheet and a charge eliminating apparatus that performs a charge eliminating process on the sheet on which the image is printed includes measuring an amount of charge on the sheet that has undergone the charge eliminating process performed by the charge eliminating apparatus, and displaying a message prompting a user to change a setting for charge elimination to be performed by the charge eliminating apparatus in a case where the amount of charge on the sheet measured in the measuring does not fall within a predetermined range.

In post-rotation control of removing an electric charge from a surface of an image bearing member in a state that the image bearing member and a developing member rotate while in contact with each other, in a case that the post-rotation control is started in a state that a recording medium is being conveyed by the image bearing member and a transfer member, i) a control portion controls a transfer voltage applying portion so as to apply a first transfer voltage in a case that the recording medium is being sandwiched between the image bearing member and the transfer member, and ii) the control portion controls the transfer voltage applying portion so as to apply a second transfer voltage that is lower than the first transfer voltage after the recording medium passes through a sandwiching portion.