Abstract: Provided is an image forming apparatus having a simple configuration capable of measuring a toner current included in a developing current and accurately calculating a toner charge amount based on the measurement result. A developing device has a developer carrier that carries a two-component developer including a magnetic carrier and toner. A developing voltage power supply applies a developing voltage obtained by superimposing an AC voltage on a DC voltage on the developer carrier. A control unit estimates a toner charge amount based on a toner current calculated by subtracting a carrier current from a developing current detected by a current detecting unit when a reference image is formed during non-image formation, and a toner developing amount calculated from the density of a reference image detected by a density detecting device.

Abstract: Provided is an image forming apparatus having a simple configuration capable of measuring a toner current included in a developing current and accurately calculating a toner charge amount based on the measurement result. The developing device has a developer carrier that carries a two-component developer including a magnetic carrier and toner. The density detecting device detects the density of the toner image. The current detecting unit detects a DC component of a developing current that flows when a developing voltage is applied to the developer carrier. The control unit, in a state in which the image carrier is rotated at two or more different linear speeds during non-image formation, forms the same reference image on the image carrier by the developing device, and estimates the toner charge amount based on the developing current when the reference image is formed and the density of the reference image.

Abstract: An image forming apparatus includes an image forming portion, a high-voltage generation circuit, a current detection portion and a control portion. The image forming portion includes an image carrying member, a charging device, an exposure device and a developing device which includes a developer carrying member for carrying a developer including a carrier and a toner. The control portion can perform a development ghost prediction mode that includes a step of measuring the amount of charge of the toner within the developing device at the time of non-image formation, a step of measuring, as a carrier current, the direct-current component of a development current when the amount of development of the toner is 0 [mg/cm2] and a step of estimating the level of occurrence of development ghost and the cause of occurrence based on the amount of charge of the toner and the carrier current which are measured.

Abstract: A mode controller outputs a characteristic value according to a DC component of a developing current measured by an ammeter at a predetermined measurement timing. The measurement timing is defined as a timing at which a non-image forming region of a surface of a photosensitive drum is located opposite to a developing roller in the entirety of an axial direction and an electric field in a direction in which a toner moves from the photosensitive drum toward the developing roller by a potential difference between a surface potential of the photosensitive drum and the DC component of a developing bias is formed in a developing nip part. A determining section determines an execution timing for a charge amount acquisition operation according to the characteristic value output by the mode controller.

Abstract: An image forming apparatus includes an image forming portion, a high-voltage generation circuit, a current detection portion and a control portion. The image forming portion includes an image carrying member, a charging device, an exposure device and a developing device which includes a developer carrying member for carrying a two-component developer. The control portion can perform a transfer memory prediction mode that includes a step of estimating, when a first reference image is formed, the level of occurrence of transfer memory based on the direct-current component of a development current flowing through the developer carrying member and a step of measuring, when the measured direct-current component of the development current is larger than a predetermined value, the amount of charge of the toner within the developing device and estimating the cause of occurrence of the transfer memory based on the measured amount of charge of the toner.

Abstract: An image forming apparatus includes an image forming portion, a high-voltage generation circuit, a current detection portion and a control portion. The image forming portion includes an image carrying member, a charging device, an exposure device and a developing device which includes a developer carrying member for carrying a developer including a carrier and a toner. The control portion can perform a development ghost prediction mode that includes a step of measuring the amount of charge of the toner within the developing device at the time of non-image formation, a step of measuring, as a carrier current, the direct-current component of a development current when the amount of development of the toner is 0 [mg/cm2] and a step of estimating the level of occurrence of development ghost and the cause of occurrence based on the amount of charge of the toner and the carrier current which are measured.

Abstract: An image forming apparatus includes a storage unit and a charging amount acquisition unit. The charging amount acquisition unit forms a measurement toner image on the image carrier while changing the frequency of the alternating current voltage of the development bias, acquires a tilt of a measurement straight line representing a relationship between the change amount of the frequency and a density change amount of the measurement toner image based on the change amount of the frequency and a result of detecting density of the measurement toner image in the density detecting unit, and acquires the charging amount of the toner based on the acquired tilt of the measurement straight line and the reference information in the storage unit.

Abstract: An image forming apparatus includes a storage unit and a charging amount acquisition unit. The charging amount acquisition unit performs a charging amount acquisition operation for forming a measurement toner image on the image carrier while changing the frequency of the alternating current voltage of the development bias with a potential difference in a direct current voltage between the developing roller and the image carrier being kept constant, acquiring a tilt of a measurement straight line representing a relationship between the change amount of the frequency and a density change amount of the measurement toner image, and acquiring the charging amount of the toner based on the acquired tilt of the measurement straight line and the reference information in the storage unit.

Abstract: An image forming apparatus includes a storage unit and a charging amount acquisition unit. The charging amount acquisition unit forms a measurement toner image on the image carrier while changing the frequency of the alternating current voltage of the development bias with the potential difference in the direct current voltage between the developing roller and the image carrier being kept constant, acquires a tilt of a measurement straight line representing a relationship between the change amount of the frequency and the density change amount of the measurement toner image, based on the change amount of the frequency and a result of detecting density of the measurement toner image in the density detecting unit, and acquires a charging amount of the toner included in the measurement toner image formed on the image carrier based on the acquired tilt of the measurement straight line and the reference information in the storage unit according to the toner density detected by the toner density detecting unit.

Abstract: An image forming apparatus includes a developer information acquisition unit. The developer information acquisition unit performs a developer deterioration information acquisition operation. In the developer deterioration information acquisition operation, the developer information acquisition unit acquires a tilt of a measurement straight line representing the relationship between the change amount of the frequency in a first measurement toner image forming operation and the density change amount of the measurement toner image based on the change amount of the frequency in the first measurement toner image forming operation and a result of detecting density of the measurement toner image in a density detecting unit, and acquires a toner charging amount based on the acquired tilt of the measurement straight line and the reference information in the storage unit so as to acquire information relating to deterioration of developer based on the acquired toner charging amount.

Abstract: In the first charge amount acquisition operation, based on density of a plurality of toner images for measurement or based on a direct component of a developing current at the time of forming the plurality of toner images in addition to the density of the plurality of toner images for measurement, the charge amount acquisition section acquires a first toner charge amount that is a charge amount of toner included in the toner image for measurement. In the second charge amount acquisition operation, based on the toner density detected at the time of image formation and a relationship between the first toner charge amount and the toner density detected in the first charge amount acquisition operation, the charge amount acquisition section acquires a second toner charge amount that is a charge amount of the toner in the development device.

Abstract: A mode controller outputs a characteristic value according to a DC component of a developing current measured by an ammeter at a predetermined measurement timing. The measurement timing is defined as a timing at which a non-image forming region of a surface of a photosensitive drum is located opposite to a developing roller in the entirety of an axial direction and an electric field in a direction in which a toner moves from the photosensitive drum toward the developing roller by a potential difference between a surface potential of the photosensitive drum and the DC component of a developing bias is formed in a developing nip part. A determining section determines an execution timing for a charge amount acquisition operation according to the characteristic value output by the mode controller.

Abstract: In the first charge amount acquisition operation, based on density of a plurality of toner images for measurement or based on a direct component of a developing current at the time of forming the plurality of toner images in addition to the density of the plurality of toner images for measurement, the charge amount acquisition section acquires a first toner charge amount that is a charge amount of toner included in the toner image for measurement. In the second charge amount acquisition operation, based on the toner density detected at the time of image formation and a relationship between the first toner charge amount and the toner density detected in the first charge amount acquisition operation, the charge amount acquisition section acquires a second toner charge amount that is a charge amount of the toner in the development device.

Abstract: An image forming apparatus has an image carrier, an electrifying member, and a charge eliminating device, and eliminates remaining charge on the surface of the image carrier by the charge eliminating device. The charge eliminating device includes a discharge member. The discharge member includes an electro conductive knit fabric knitted in a cylindrical shape using twisted yarn made of twisted metal fibers and a support member having a cylindrical shape and inserted in the electro conductive knit fabric, and is disposed to face the image carrier in a noncontact manner. A magnet member is disposed inside the image carrier within a charge elimination nip width between two tangential lines of an outer circumference surface of the discharge member, the two tangential lines being parallel to a straight line passing through a rotation center of the image carrier and a center axis of the discharge member.

Abstract: An image forming apparatus includes a storage unit and a charging amount acquisition unit. The charging amount acquisition unit forms a measurement toner image on the image carrier while changing the frequency of the alternating current voltage of the development bias with the potential difference in the direct current voltage between the developing roller and the image carrier being kept constant, acquires a tilt of a measurement straight line representing a relationship between the change amount of the frequency and the density change amount of the measurement toner image, based on the change amount of the frequency and a result of detecting density of the measurement toner image in the density detecting unit, and acquires a charging amount of the toner included in the measurement toner image formed on the image carrier based on the acquired tilt of the measurement straight line and the reference information in the storage unit according to the toner density detected by the toner density detecting unit.

Abstract: An image forming apparatus includes a developer information acquisition unit. The developer information acquisition unit performs a developer deterioration information acquisition operation. In the developer deterioration information acquisition operation, the developer information acquisition unit acquires a tilt of a measurement straight line representing the relationship between the change amount of the frequency in a first measurement toner image forming operation and the density change amount of the measurement toner image based on the change amount of the frequency in the first measurement toner image forming operation and a result of detecting density of the measurement toner image in a density detecting unit, and acquires a toner charging amount based on the acquired tilt of the measurement straight line and the reference information in the storage unit so as to acquire information relating to deterioration of developer based on the acquired toner charging amount.

Abstract: An image forming apparatus includes a storage unit and a charging amount acquisition unit. The charging amount acquisition unit performs a charging amount acquisition operation for forming a measurement toner image on the image carrier while changing the frequency of the alternating current voltage of the development bias with a potential difference in a direct current voltage between the developing roller and the image carrier being kept constant, acquiring a tilt of a measurement straight line representing a relationship between the change amount of the frequency and a density change amount of the measurement toner image, and acquiring the charging amount of the toner based on the acquired tilt of the measurement straight line and the reference information in the storage unit.

Abstract: An image forming apparatus includes a storage unit and a charging amount acquisition unit. The charging amount acquisition unit forms a measurement toner image on the image carrier while changing the frequency of the alternating current voltage of the development bias, acquires a tilt of a measurement straight line representing a relationship between the change amount of the frequency and a density change amount of the measurement toner image based on the change amount of the frequency and a result of detecting density of the measurement toner image in the density detecting unit, and acquires the charging amount of the toner based on the acquired tilt of the measurement straight line and the reference information in the storage unit.

Abstract: A developing device includes a developing roller and a layer thickness regulating member. The developing roller includes a fixed magnet and a sleeve. The layer thickness regulating member includes a regulating body portion and an upstream regulating portion, and the upstream regulating portion includes an upstream magnetic member and a nonmagnetic member. Developer is hardly strongly jammed in an area between a first magnetic field concentration point of the regulating body portion and a second magnetic field concentration point of the upstream regulating portion. Thus, even if the sleeve of the developing roller is rotated at a higher speed than before, the developer is stably regulated by the layer thickness regulating member.

Abstract: A developing device includes a developing roller and a layer thickness regulating member. The developing roller includes a fixed magnet and a sleeve. The layer thickness regulating member includes a regulating body portion and an upstream regulating portion, and the upstream regulating portion includes an upstream magnetic member and a nonmagnetic member. Developer is hardly strongly jammed in an area between a first magnetic field concentration point of the regulating body portion and a second magnetic field concentration point of the upstream regulating portion. Thus, even if the sleeve of the developing roller is rotated at a higher speed than before, the developer is stably regulated by the layer thickness regulating member.