Abstract: An image forming apparatus includes an image bearing member; a charging member for contacting a peripheral surface of the image bearing member to electrically charge the peripheral surface; a first developing device for forming a first developed image on the peripheral surface of the image bearing member charged by the charging member; a second developing device for forming a second developed image on the peripheral surface, wherein a combined developed image is formed by superimposing the first developed image and the second developed image on a common transfer material, wherein when the combined image is being formed, the charging member is cleaned by transferring, by an electric field, material deposited on the charging member to a region between the first developed image and the second developed image on the peripheral surface of the image bearing member, and wherein the first developed image and the second developed image are not formed in the region.

Abstract: A developing apparatus, a process cartridge and an image forming apparatus which form an image whose image density can be maintained, which form a fogged image and which form an image of uneven density within an acceptable range, even when the diameter of a developer carrying member is not more than 12 mm. The apparatus includes a developer carrying member whose outer diameter is in the range of 8 mm to 12 mm, and a magnetic mono-component developer 43 having a saturation magnetization of in a range of 20 Am2/kg to 37 Am2/kg when the magnetic field of 79.6 kA/m (1000 oersteds) is applied, the magnetization of not less than 70% and not more than 80% of the saturation magnetization when the magnetic field is lowered to 55.7 kA/m (700 oersteds), and the magnetization of not less than 50% and not more than 62% of the saturation magnetization when the magnetic field is lowered to 39.8 kA/m (500 oersteds).

Abstract: A developing apparatus, a process cartridge and an image forming apparatus of which the image density can be maintained and the fogged image and the uneven density can be within an acceptable level even when the diameter of a developer carrying member is not more than 12 mm. The outer diameter of the developer carrying member 41 is not less than 8 mm and not more than 12 mm, and a magnetic mono-component developer 43 has a saturation magnetization of not less than 20 Am2/kg and not more than 37 Am2/kg when the magnetic field of 79.6 kA/m (1000 oersteds) is applied, the magnetization of not less than 70% and not more than 80% of the saturation magnetization when the magnetic field is lowered to 55.7 kA/m (700 oersteds), and the magnetization of not less than 50% and not more than 62% of the saturation magnetization when the magnetic field is lowered to 39.8 kA/m (500 oersteds).

Abstract: An image forming apparatus includes a photosensitive drum, a charge roller for charging the photosensitive drum, a developing device for developing an electrostatic latent image formed on the charged photosensitive drum with a developer, a first auxiliary charging brush which is located upstream from the charge roller in a movement direction of a surface of the photosensitive drum and applies a voltage of a polarity opposite to a normal polarity of a polarity opposite to a normal polarity of the developer, and a second auxiliary charging brush which is located downstream from the first auxiliary charging brush and upstream from the charge roller and applies a voltage of a polarity identical to the normal polarity of the developer. In the image forming apparatus, the first auxiliary charging brush is supplied with an AC voltage to be improved in recovery performance of a transfer residual developer, and contamination of charging means can be prevented.

Abstract: An image forming apparatus has: a photosensitive drum onto which images are formed; and a primary transfer roller which sequentially forms the color images onto the photosensitive drum by using a plurality of developing devices having different color developers and transfers the color images formed on the drum onto a transfer member or a recording medium. Order of forming the images onto an image bearing member on a photosensitive member is switched based on a use amount of each of the plurality of developing devices.

Abstract: A unit includes cartridge electrical contacts provided at respective ends of the cartridge in a longitudinal direction and electrically connecting with body electrical contacts when the cartridge is properly mounted to the image forming apparatus. The cartridge electrical contacts are electrically connected to each other. Mounting the cartridge to the image forming apparatus forms a detection circuit via the cartridge.

Abstract: An image forming apparatus includes an image bearing member; a charging member for contacting a peripheral surface of the image bearing member to electrically charge the peripheral surface; a first developing device for forming a first developed image on the peripheral surface of the image bearing member charged by the charging member; a second developing device for forming a second developed image on the peripheral surface, wherein a combined developed image is formed by superimposing the first developed image and the second developed image on a common transfer material, wherein when the combined image is formed, the charging member is cleaned by transferring material deposited on the charging member to a region between the first developed image and the second developed image on the peripheral surface of the image bearing member, and wherein the first developed image or the second developed image is not formed in the region.

Abstract: An image forming apparatus includes a photosensitive drum, a charging roller, a transfer roller, and a toner charging brush, wherein the toner charging brush reciprocates in a longitudinal direction of the photosensitive drum. In the image forming apparatus, when a number of rotations per a unit time of the image bearing member is assumed to be “a” and a number of times of reciprocation per unit time of the toner charging brush is assumed to be “b” assuming that R=b/a, R is set to be in a range of 1/25?R?3. However, R=m/n (m and n are integers of 5 or less) is excluded. Consequently, generation of a periodic attachment pattern appearing on the photosensitive drum is eliminated.

Abstract: A unit includes cartridge electrical contacts provided at respective ends of the cartridge in a longitudinal direction and electrically connecting with body electrical contacts when the cartridge is properly mounted to the image forming apparatus. The cartridge electrical contacts are electrically connected to each other. Mounting the cartridge to the image forming apparatus forms a detection circuit via the cartridge.

Abstract: An image forming apparatus includes a photosensitive drum, a charge roller for charging the photosensitive drum, a developing device for developing an electrostatic latent image formed on the charged photosensitive drum with a developer, a first auxiliary charging brush which is located upstream from the charge roller in a movement direction of a surface of the photosensitive drum and applies a voltage of a polarity opposite to a normal polarity of a polarity opposite to a normal polarity of the developer, and a second auxiliary charging brush which is located downstream from the first auxiliary charging brush and upstream from the charge roller and applies a voltage of a polarity identical to the normal polarity of the developer. In the image forming apparatus, the first auxiliary charging brush is supplied with an AC voltage to be improved in recovery performance of a transfer residual developer, and contamination of charging means can be prevented.

Abstract: An image forming apparatus includes a photosensitive drum, a charging roller, a transfer roller, and a toner charging brush, wherein the toner charging brush reciprocates in a longitudinal direction of the photosensitive drum. In the image forming apparatus, when a number of rotations per a unit time of the image bearing member is assumed to be “a” and a number of times of reciprocation per unit time of the toner charging brush is assumed to be “b” assuming that R=b/a, R is set to be in a range of ½?R?3. However, R=m/n (m and n are integers of 5 or less) is excluded. Consequently, generation of a periodic attachment pattern appearing on the photosensitive drum is eliminated.

Abstract: An image forming apparatus includes a photosensitive drum, a charge roller for charging the photosensitive drum, a developing device for developing an electrostatic latent image formed on the charged photosensitive drum with a developer, a first auxiliary charging brush which is located upstream from the charge roller in a movement direction of a surface of the photosensitive drum and applies a voltage of a polarity opposite to a normal polarity of a polarity opposite to a normal polarity of the developer, and a second auxiliary charging brush which is located downstream from the first auxiliary charging brush and upstream from the charge roller and applies a voltage of a polarity identical to the normal polarity of the developer. In the image forming apparatus, the first auxiliary charging brush is supplied with an AC voltage to be improved in recovery performance of a transfer residual developer, and contamination of charging means can be prevented.

Abstract: An image forming apparatus includes a photosensitive drum, a charging roller, a transfer roller, and a toner charging brush, wherein the toner charging brush reciprocates in a longitudinal direction of the photosensitive drum. In the image forming apparatus, when a number of rotations per a unit time of the image bearing member is assumed to be “a” and a number of times of reciprocation per unit time of the toner charging brush is assumed to be “b”, assuming that R=b/a, R is set to be in a range of 1/25?R?3. However, R=m/n (m and n are integers of 5 or less) is excluded. Consequently, generation of a periodic attachment pattern appearing on the photosensitive drum is eliminated.

Abstract: A process cartridge includes an image bearing member, a developing device developing an electrostatic image on the member using developer to form a developer image on the member and a developer charger charging residual developer on the member disposed downstream of a transferring position at which the developer image is transferred onto a transfer destination member and upstream of a position at which the electrostatic image is formed on the member with respect to the moving direction of the member. The developer charger is in contact with the member and is movable in the longitudinal direction of the member upon charging the residual developer. L1+d?L2 when L1 is the developing width of the developing device, L2 is the contact width of the developer charger with the member, and d is the width of movement of the developer charger in the longitudinal direction of the member.

Abstract: To provide an image forming apparatus improving discharging of a developer from charge providing member for providing charge to the developer remaining on an image bearing member to the image bearing member, the developer is charged from the charge providing member to the image bearing member. When a developer discharging region of the image bearing member is disposed at a charging position, charging member is applied with a voltage having a direct current component of an absolute value equal to or smaller than an absolute value of voltage applied to the charge providing member without an alternating current component.

Abstract: An image forming apparatus includes a photosensitive drum, a charge roller for charging the photosensitive drum, a developing device for developing an electrostatic latent image formed on the charged photosensitive drum with a developer, a first auxiliary charging brush which is located upstream from the charge roller in a movement direction of a surface of the photosensitive drum and applies a voltage of a polarity opposite to a normal polarity of a polarity opposite to a normal polarity of the developer, and a second auxiliary charging brush which is located downstream from the first auxiliary charging brush and upstream from the charge roller and applies a voltage of a polarity identical to the normal polarity of the developer. In the image forming apparatus, the first auxiliary charging brush is supplied with an AC voltage to be improved in recovery performance of a transfer residual developer, and contamination of charging means can be prevented.

Abstract: A process cartridge adapted to be detachably attached to a body of an image forming apparatus comprises an image bearing member, developing means for developing an electrostatic image formed on the image bearing member by using developer to form a developer image on the image bearing member and developer charging means for charging residual developer on the image bearing member disposed downstream of a transferring position at which said developer image is transferred onto a transfer destination member and upstream of a position at which the electrostatic image is formed on said image bearing member with respect to the moving direction of said image bearing member. The developer charging means can be in contact with the image bearing member and is movable in a direction substantially the same as a longitudinal direction of the image bearing member upon charging the residual developer.

Abstract: An image forming apparatus has an image bearing member; and a charging member forming a nip with the image bearing member to charge the image bearing member. Conductive particles are provided in the nip and a time factor &agr; represented by a following equation satisfies a condition &agr;>15: &agr;=2&pgr;·k·Nc·(W/Vc)/(&rgr;·Cd·Z) Z=−0.5·1n(&pgr;·k·Nc)−1n({square root over (&bgr;)}·D/2) (&bgr;=1.

Abstract: Provided is an image forming apparatus, which includes a photosensitive drum, a charging roller, a transfer roller, and a toner charging brush, reciprocates the toner charging brush in a longitudinal direction of the photosensitive drum. In the image forming apparatus, when a number of rotations per a unit time of the image bearing member is assumed to be “a” and a number of times of reciprocation per unit time of the toner charging brush is assumed to be “b”, assuming that R=b/a, R is set to be in a range of {fraction (1/25)}≦R≦3. However, R=m/n (m and n are integers of 5 or less) is excluded. Consequently, generation of a periodic attachment pattern appearing on the photosensitive drum is eliminated.

Abstract: To provide an image forming apparatus improving discharging of a developer from charge providing means for providing charge to the developer remaining on an image bearing member to the image bearing member, the developer is charged from the charge providing means to the image bearing member. When a developer discharging region of the image bearing member is disposed at a charging position, charging means is applied with a voltage having a direct current component of an absolute value equal to or smaller than an absolute value of voltage applied to the charge providing means without an alternating current component.