Abstract: An image forming apparatus includes a density detector that detects a density of a fog image formed on an image bearing member, a temporary determiner that determines a temporary fog margin which is a fog margin representing a difference between a developing bias to be applied to a toner bearing member and a charging bias to be applied to a charging device for charging the image bearing member based on a density detected by the density detector, and a corrector that corrects the temporary fog margin based on a change rate of a density detected by the density detector with respect to a change of a fog margin.

Abstract: An image forming apparatus includes a density detector that detects a density of a fog image formed on an image bearing member, a temporary determiner that determines a temporary fog margin which is a fog margin representing a difference between a developing bias to be applied to a toner bearing member and a charging bias to be applied to a charging device for charging the image bearing member based on a density detected by the density detector, and a corrector that corrects the temporary fog margin based on a change rate of a density detected by the density detector with respect to a change of a fog margin.

Abstract: An image formation apparatus includes a first electrode portion including a contact electrode and a counter electrode, a second electrode portion arranged as not being in contact with a recording medium, a first sensing unit configured to sense a first current which flows to the first electrode portion as a result of application of a voltage across the contact electrode and the counter electrode while the recording medium lies between the contact electrode and the counter electrode, a second sensing unit configured to sense a second current which flows from the charged recording medium to the second electrode portion, and a control unit. The control unit sets a transfer condition for transferring a toner image to the recording medium based on the first current sensed by the first sensing unit and the second current sensed by the second sensing unit.

Abstract: An image forming apparatus includes: a photoreceptor including a surface layer; a storage that stores a target value of a variation of a film thickness of the surface layer; and a hardware processor that acquires a variation of the film thickness in a first period within which the photoreceptor rotates a predetermined number of times, and sets a margin that is an amount of a portion for allowance with respect to a proper value of a parameter related to control of the photoreceptor, the margin being to be employed after the first period.

Abstract: An image forming apparatus includes: a photoreceptor including a surface layer; a storage that stores a target value of a variation of a film thickness of the surface layer; and a hardware processor that acquires a variation of the film thickness in a first period within which the photoreceptor rotates a predetermined number of times, and sets a margin that is an amount of a portion for allowance with respect to a proper value of a parameter related to control of the photoreceptor, the margin being to be employed after the first period.

Abstract: An image formation apparatus includes a first electrode portion including a contact electrode and a counter electrode, a second electrode portion arranged as not being in contact with a recording medium, a first sensing unit configured to sense a first current which flows to the first electrode portion as a result of application of a voltage across the contact electrode and the counter electrode while the recording medium lies between the contact electrode and the counter electrode, a second sensing unit configured to sense a second current which flows from the charged recording medium to the second electrode portion, and a control unit. The control unit sets a transfer condition for transferring a toner image to the recording medium based on the first current sensed by the first sensing unit and the second current sensed by the second sensing unit.

Abstract: An image forming apparatus includes: a photosensitive member; a power supply that applies a bias voltage to the photosensitive member to charge a surface of the photosensitive member; a developer that develops an electrostatic latent image on the photosensitive member; an exposing device that forms the electrostatic latent image on the photosensitive member; a hardware processor; and a memory, wherein the memory stores, in advance, a relationship between a suitable AC voltage at which a discharge amount of AC electric discharge is balanced between positive and negative sides and a current value of a specific AC voltage, and the hardware processor controls the bias voltage in an AC charging type, detects the current value at the specific AC voltage, and determines a setting AC voltage on the basis of the relationship.

Abstract: A developing device is equipped with a developing roller rotationally driven for developing an electrostatic latent image formed on a surface of an image supporting body with toner, a screw rotationally driven of which a ratio of number of rotations to number of rotations of the developing roller being rotationally driven is constant, and a processor. The processor is configured to detect toner density in developer by using a sensor installed facing the screw, during rotationally drive of the screw, and detect information indicating a rotational position of the developing roller, based on ripples which occur in the toner density detected.

Abstract: A developing device includes a developer carrying member and first and second conveyance members. The first conveyance member conveys a developer in a first direction through a first conveyance path to the developer carrying member. The second conveyance member conveys the developer in a second direction through a second conveyance path included in a circulation path along with the first conveyance path. The second conveyance member has a helical second screw around a second shaft. The second conveyance path includes a developer replenishing port and a developer discharge port. The second screw is approximately constant in diameter in a second section being a portion extending a predetermined distance from an end of the discharge port in the second direction when viewed in a top view. The second screw conveys the developer at a lower speed in the second section than on an upstream side with respect to the second section.

Abstract: An image forming device includes: a charging unit configured to apply charging bias voltage to a charging member and charge a surface of an image carrying body; an exposure unit configured to expose the surface of the image carrying body, and form an electrostatic latent image; a developing unit configured to apply developing bias voltage to a developer carrying body, and develop the electrostatic latent image; and a control unit configured to control timing to start applying the developing bias voltage relative to timing to start applying the charging bias voltage, wherein the control unit performs control such that the larger an absolute value of the charging bias voltage is, the shorter an interval from timing to start applying the charging bias voltage to timing to start applying the developing bias voltage becomes, and such that the smaller the absolute value is, the longer the interval becomes.

Abstract: A developing device is equipped with a developing roller rotationally driven for developing an electrostatic latent image formed on a surface of an image supporting body with toner, a screw rotationally driven of which a ratio of number of rotations to number of rotations of the developing roller being rotationally driven is constant, and a processor. The processor is configured to detect toner density in developer by using a sensor installed facing the screw, during rotationally drive of the screw, and detect information indicating a rotational position of the developing roller, based on ripples which occur in the toner density detected.

Abstract: There are provided a developing device including a developing roller to develop an image carrier by use of a two-component developer and a developing bias power source, and an image forming apparatus using the developing device. The developing device further includes a variable resistance unit provided on a bias apply path to apply a bias from the developing power source to the developing roller, and a resistance controller to control a resistance value of the variable resistance unit based on a charge amount signal indicating a toner's charge amount in a developer layer on the developing roller. The resistance controller provides a low mode to lower the resistance of the variable resistance unit and a high mode to enhance the resistance. The low mode is set if the toner charge amount is low, and the high mode is set if the toner charge amount is high.

Abstract: A damage amount determination device, which is used for an image forming device that forms an image on paper, includes an information acquisition unit that acquires information related to whiteness of the paper used for printing and a damage amount determination unit that determines an amount of damage, which is caused by the paper to a predetermined component of the image forming device when the paper passes through the predetermined component, based on the information related to the whiteness.

Abstract: A developing apparatus that develops an electrostatic latent image on an image supporting body using developer including toner and carrier includes a circulation path where the developer circulates, a discharge path connected to the circulation path through which some of the developer passes, and a first recycle path connected to the discharge path and allowing some of the developer flowing into the discharge path to return to the circulation path. The discharge path includes a discharge opening for discharging the developer flowing into the discharge path, and a first return opening for connecting to the first recycle path. The first return opening is located on an upper side in a vertical direction with respect to the discharge opening and located on an upstream side in a pass-through direction of the developer flowing into the discharge path.

Abstract: An image forming device includes: a charging unit configured to apply charging bias voltage to a charging member and charge a surface of an image carrying body; an exposure unit configured to expose the surface of the image carrying body, and form an electrostatic latent image; a developing unit configured to apply developing bias voltage to a developer carrying body, and develop the electrostatic latent image; and a control unit configured to control timing to start applying the developing bias voltage relative to timing to start applying the charging bias voltage, wherein the control unit performs control such that the larger an absolute value of the charging bias voltage is, the shorter an interval from timing to start applying the charging bias voltage to timing to start applying the developing bias voltage becomes, and such that the smaller the absolute value is, the longer the interval becomes.

Abstract: There are provided a developing device comprising a developing roller to develop an image carrier by use of a two-component developer and a developing bias power source, and an image forming apparatus using the developing device. The developing device further includes a variable resistance unit provided on a bias apply path to apply a bias from the developing power source to the developing roller, and a resistance controller to control a resistance value of the variable resistance unit based on a charge amount signal indicating a toner's charge amount in a developer layer on the developing roller. The resistance controller provides a low mode to lower the resistance of the variable resistance unit and a high mode to enhance the resistance. The low mode is set if the toner charge amount is low, and the high mode is set if the toner charge amount is high.

Abstract: A developing device includes a developer carrying member and first and second conveyance members. The first conveyance member conveys a developer in a first direction through a first conveyance path to the developer carrying member. The second conveyance member conveys the developer in a second direction through a second conveyance path included in a circulation path along with the first conveyance path. The second conveyance member has a helical second screw around a second shaft. The second conveyance path includes a developer replenishing port and a developer discharge port. The second screw is approximately constant in diameter in a second section being a portion extending a predetermined distance from an end of the discharge port in the second direction when viewed in a top view. The second screw conveys the developer at a lower speed in the second section than on an upstream side with respect to the second section.

Abstract: A developing apparatus that develops an electrostatic latent image on an image supporting body, using developer including toner and carrier, includes: a circulation path where the developer circulates; a discharge path which is connected to the circulation path and through which some of the developer passes; and a first recycle path connected to the discharge path and allowing some of the developer flowing into the discharge path to return to the circulation path, wherein the discharge path is provided with: a discharge opening for discharging the developer flowing into the discharge path; and a first return opening for connecting to the first recycle path, and the first return opening is located on an upper side in a vertical direction with respect to the discharge opening and located on an upstream side in a pass-through direction of the developer flowing into the discharge path.

Abstract: A damage amount determination device, which is used for an image forming device that forms an image on paper, includes an information acquisition unit that acquires information related to whiteness of the paper used for printing and a damage amount determination unit that determines an amount of damage, which is caused by the paper to a predetermined component of the image forming device when the paper passes through the predetermined component, based on the information related to the whiteness.