An image forming apparatus includes an image bearing member, an intermediary transfer belt, a transfer member, a voltage source for applying a voltage to the transfer member, a detecting portion for detecting a current flowing through the transfer member, and a controller for carrying out constant-voltage control so that the voltage applied to the transfer member becomes a target voltage when a recording material P passes through a transfer portion. The controller is capable of changing the voltage applied to the transfer member so that a detection result detected by the detecting portion during transfer falls within a predetermined range. The controller changes the predetermined range on the basis of the detection result detected by the detecting portion when the voltage is applied to the transfer member in a state in which the recording material P is absent in the transfer portion.

A static elimination device includes: a first static elimination member that makes contact with a medium that is transported; a second static elimination member arranged such that the medium is inserted between the first static elimination member and the second static elimination member; and a power source that applies a voltage to at least one of the first static elimination member or the second static elimination member, in which at least one of the first static elimination member and the second static elimination member has an elastic body.

Paper physical property detecting device includes a first detector that measures a sheet of paper (hereinafter, merely referred to as a paper) made to stop temporarily on a conveyance path and acquires a first value corresponding to a first physical property, a second detector that measures a paper while conveying the paper on the conveyance path and acquires a second value corresponding to a second physical property with regard to a physical property different from the first physical property; and a corrector that corrects the first value on a basis of the second value and creates post correction data.

An image forming apparatus includes an image bearing member, an intermediary transfer belt, a transfer member, a voltage source for applying a voltage to the transfer member, a detecting portion for detecting a current flowing through the transfer member, and a controller for carrying out constant-voltage control so that the voltage applied to the transfer member becomes a target voltage when a recording material P passes through a transfer portion. The controller is capable of changing the voltage applied to the transfer member so that a detection result detected by the detecting portion during transfer falls within a predetermined range. The controller changes the predetermined range on the basis of the detection result detected by the detecting portion when the voltage is applied to the transfer member in a state in which the recording material P is absent in the transfer portion.

An image forming apparatus includes an image bearing member, an intermediary transfer belt, a transfer member, a voltage source for applying a voltage to the transfer member, a detecting portion for detecting a current flowing through the transfer member, and a controller for carrying out constant-voltage control so that the voltage applied to the transfer member becomes a target voltage when a recording material P passes through a transfer portion. The controller is capable of changing the voltage applied to the transfer member so that a detection result detected by the detecting portion during transfer falls within a predetermined range. The controller changes the predetermined range on the basis of the detection result detected by the detecting portion when the voltage is applied to the transfer member in a state in which the recording material P is absent in the transfer portion.

An information which includes an image bearing member 1, an intermediary transfer belt 7, a transfer member 8, a voltage source 20 for applying a voltage to the transfer member 8, a detecting portion 21 for detecting a current flowing through the transfer member 8, and a controller 50 for carrying out constant-voltage control so that the voltage applied to the transfer member when a recording material P passes through a transfer portion N2 and in which the controller 50 is capable of changing the voltage applied to the transfer member 8 so that a detection result detected by the detecting portion 21 during transfer falls within a predetermined pass has a constitution in which said controller 50 changes the predetermined range on the basis of the detection result detected by the detecting portion 21 when the voltage is applied to the transfer member 8 in a state in which the recording material P is absent in the transfer portion N2.

A static elimination device includes: a first static elimination member that makes contact with a medium that is transported; a second static elimination member arranged such that the medium is inserted between the first static elimination member and the second static elimination member; and a power source that applies a voltage to at least one of the first static elimination member or the second static elimination member, in which at least one of the first static elimination member and the second static elimination member has an elastic body.

Paper physical property detecting device includes a first detector that measures a sheet of paper (hereinafter, merely referred to as a paper) made to stop temporarily on a conveyance path and acquires a first value corresponding to a first physical property, a second detector that measures a paper while conveying the paper on the conveyance path and acquires a second value corresponding to a second physical property with regard to a physical property different from the first physical property; and a corrector that corrects the first value on a basis of the second value and creates post correction data.

An image forming apparatus includes a plurality of image carriers, an intermediate transfer body, a plurality of primary transfer members, a secondary transfer member, a first guide member, and a controller. The first guide member guides a recording medium along a conveying direction. The controller controls a primary transfer bias and a secondary transfer bias. A plurality of the primary transfer members include an upstream side primary transfer member and a downstream side primary transfer member. The controller makes an absolute value of the primary transfer bias applied to the downstream side primary transfer member larger than an absolute value of the primary transfer bias applied to the upstream side primary transfer member. The controller lowers an absolute value of the secondary transfer bias when the recording medium separates from the first guide member.

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.