Ricoh Company, Ltd.

Sharp Kabushiki Kaisha Corporation

Yoshio Sakagawa

Yuji Nagatomo

Tetsumaru Fujita

Shin Murayama

Jun Yamaguchi

Yasuyuki Ishiguro

Hiroshi Kubota

Shin Yamamoto

Yoshiko Ogawa

Yasuhide Matsuno

Takeshi Takayama

A developing device includes a developer bearer and a regulation member. The developer bearer bears developer on a surface thereof. The developer bearer is rotatable forward and in reverse. The regulation member is disposed in contact or non-contact with the surface of the developer bearer to regulate amount of the developer on the developer bearer. In a non-development period, when the developer bearer rotates in a direction of reverse rotation opposite to a direction of forward rotation in which the developer bearer rotates in a development period, the developer bearer stops a series of rotating operations after the developer bearer rotates in the direction of forward rotation as a last rotating operation. A total rotation amount of forward rotation is set to be greater than a total rotation amount of reverse rotation in the series of rotating operations.

Developing device and image forming apparatus including same

An image forming apparatus includes a rotatable photoconductor, a charging unit, an exposure unit to expose the photoconductor to reduce an electrical potential at the photoconductor, a developing unit to charge the toner held on a toner bearing member with friction and attract the toner to the exposed portion on the photoconductor by supplying a development voltage from a first power source and using an electrical potential difference between the toner bearing member and the photoconductor in the development area, a reverse development voltage controller to supply a reverse development voltage while a non-charged portion on the photoconductor passes the development area, and a developer reducing potential applier to supply a development restraining potential and an absolute value smaller than a target charging potential to the photoconductor while the reverse development voltage is supplied.

Image forming apparatus including a controller configured to regulate a potential difference between a photoconductor and a developing member

An image forming apparatus that is more capable of preventing the occurrence of image quality deterioration caused by defective charging of a photoreceptor than the conventional one. As a charging device, there is used a member which has: a conductive sheet that causes the surface thereof applied with a predetermined bias to abut against the surface of the photoreceptor after passing through a primary transfer nip obtained by abutment between the photoreceptor and an intermediate transfer belt and before entering a development step performed by a developing device; a conductive brush member that applies a predetermined bias to the surface of the photoreceptor obtained after passing through the position of abutment with the sheet and before entering the development step; and a charging roller that uniformly charges the surface of the photoreceptor after passing through the position of abutment with the brush and before entering the development step. Furthermore, at least during a predetermined first period, a bias having a polarity same as the uniformly charging polarity of the photoreceptor is applied to the conductive sheet and brush member.

Image forming apparatus

An image forming apparatus capable of maintaining cleaning performance of a cleaning brush and downsizing the apparatus main body. Transfer residual toner accumulated on the cleaning brush is transferred onto a photoreceptor by an electrostatic force, hence the cleaning brush becomes clean and the cleaning performance thereof improves. Therefore, the photoreceptor and a charging roller can be cleaned well by the cleaning brush over a long period of time, and the photoreceptor can be charged well by the charging roller over a long period of time. Moreover, because the transfer residual toner that is transferred from the cleaning brush onto the photoreceptor is recovered by a developing device, it is not necessary to provide the apparatus main body with a toner recovery portion that is specially designed for recovering the transfer residual toner, hence the apparatus main body can be downsized.

The present invention provides an image forming apparatus in which the cleaning performance of a cleaning brush is preserved over time while affording a smaller apparatus main body. During a print job, toner recovered from a charging roller to a cleaning brush is transferred from the cleaning brush to a cleaning auxiliary roller, thereby preventing excessive accumulation of toner in the cleaning brush. During non print job times, toner accumulated in the cleaning brush is transferred to the charging roller directly and via the cleaning auxiliary roller, whereby the cleaning brush becomes clean while preserving its cleaning performance. Also, toner transferred to the charging roller is transferred to a photosensitive unit is recovered into a developing device, which does away with the need for a dedicated recovery toner holding portion for recovering residual toner, thereby reducing the size of the apparatus main body.

An image forming apparatus includes: an image carrying member having a movable surface; a charging device including a rotatable charging member which is supplied with a voltage including a direct voltage superimposed with an alternating voltage, and which contacts and charges the image carrying member; an electrostatic latent image forming device for forming an electrostatic latent image on the image carrying member; and a development device for developing the electrostatic latent image. The frequency of the alternating voltage is lower in a non-image forming area than in an image forming area. In the non-image forming area, the image carrying member is charged to a surface potential having a waveform shape in accordance with the alternating voltage, and the potential difference between the surface potential and the voltage applied to the charging member generates an electric field which moves toner adhering to the charging member to the image carrying member.

Image forming method and apparatus which uses alternating voltage to form an electric field for moving toner

A brush member includes plural raisings and contacts a surface of an image bearer downstream of a transfer station and temporary captures toner remaining on the surface of the image bearer into the brush member in a toner capturing process. The brush member returns the toner to the surface of the image bearer at a prescribed time in a toner returning process. A bending direction of the plural raisings is opposite in the returning process to that in the toner capturing process.

Image forming apparatus including a brush member to temporarily capture toner

A cleanerless image forming apparatus configured to reduce the density unevenness of halftone images. The apparatus includes a photosensitive member, a charging roller device for uniformly charging the surface of the photosensitive member, an optical writing unit for forming latent images on the surface of the photosensitive member after uniform charging, a developing device for developing the latent toner image on the photosensitive member, a transfer unit for transferring the toner image to an intermediate transfer belt, and a brush member for trapping post-transfer residual toner adhering to the surface of the photosensitive member after passing through the transfer process by the transfer unit and before entering the developing process by the developing device, wherein the post-transfer residual toner is recovered within the developing device after re-transfer of the post-transfer residual toner within the brush member to the surface of the photosensitive member.

Cleanerless image forming apparatus

An image forming apparatus, performing a corresponding method of image forming, includes an image carrier, a writing unit, a developing unit, a charging member configured to rotate continuously with the image carrier at a portion contacting the image carrier and uniformly charge a surface of the image carrier while contacting a surface thereof with the surface of the image carrier, a charge bias applying unit configured to apply a charge bias to the charging member, and a controller configured to control of driving of the image carrier and the charging member and reduce at a charge nip at a given timing a linear velocity ratio of a travel speed of the surface of the charging member to a travel speed of the surface of the image carrier.

Image forming method and apparatus for effectively charging an image carrier

An electrifying apparatus, a processing unit including the electrifying apparatus, and an image formation apparatus including the electrifying apparatus. The electrifying apparatus includes a conductive sheet for electrifying at least one of a surface of a photoconductor and toner adhered to the surface. The conductive sheet is specified to have a pure-water contact angle equal to or greater than 108 degrees, and to have a shore D hardness equal to or less than 65.

Electrifying apparatus, a processing unit, and an image formation apparatus

An image forming apparatus includes either one of a process cartridge and a development device. The process cartridge is attachable to and detachable from the image forming apparatus, and integrally includes the development device. The development device includes a developer supplying member and a developer carrying member, at least one of which is formed of an elastic material, and which rotate in contact with each other. The developer supplying member is provided to be displacable in directions of contacting with and separating from the developer carrying member, and is biased toward the developer carrying member by predetermined biasing force.

Development device for developing an electrostatic latent image formed on an image carrying member into a visible image

A charging device and an image forming apparatus using the charging device. The charging device includes a charging member to uniformly charge a surface of a latent image bearing member in contact therewith, a charge bias application unit to apply a charge bias to the charging member, a conductive member to contact a surface of the charging member, and a different-valued bias application unit to apply a different-valued bias different from the charge bias to the conductive member. The image forming apparatus includes a latent image bearing member to bear a latent image, a latent image forming unit to form the latent image on the latent image bearing member, a development unit to develop the latent image with toner, and the charging device.

Charging device for charging a surface of a latent image bearing member and an image forming apparatus including the charging device

An image forming apparatus includes at least a latent image carrier, a latent image forming mechanism, a developing mechanism and a charger. The latent image carrier bears a latent image. The latent image forming mechanism forms the latent image on the latent image carrier. The developing mechanism develops the latent image on the latent image carrier with toner. The charger includes a conductive member supplied with a bias voltage while contacting a surface of the latent image carrier, and charges at least one of the surface of the latent image carrier and a toner adhering to the surface thereof through the conductive member. A tensile strength of the conductive member at break is no less than 10 MPa and no more than 40 MPa, and a contact pressure between the conductive member and the latent image carrier is no less than 4 kN/mand no more than 15 kN/m.

Process unit and image forming apparatus including the same

An image forming apparatus includes a charging device for charging a photosensitive element having a moving surface, by bringing a charging roller, to which voltage is applied, into pressure-contact with the photosensitive element, wherein to the charging member there is applied voltage for forming an electric field such that toner adhered to the charging roller surface at a non-image forming area is oriented towards the photosensitive element. The image forming apparatus is provided with pressure contact force modifying means for making the pressure contact force of the charging roller against the photosensitive element at the non-image forming area greater than that at an image forming area.

Cleaning of a charging member in an image forming apparatus

A particle discharge apparatus includes cylindrical particle discharge unit(s) having toner dispensing outlet(s) provided at upper portion(s) on one side of particle discharge unit(s), and particle discharge outlet(s) provided at lower portion(s) on the other side of particle discharge unit(s); and conveyor screw(s), provided at the interior of particle discharge unit(s), having rotatable shaft(s) and helical conveyor vane(s) secured to rotatable shaft(s). The conveyor vane(s) is/are divided into first vane segment(s) and second vane segment(s); and wherein there is/are vaneless region(s), where no portion of conveyor vane(s) is present, between first vane segment(s) and second vane segment(s).

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Hyogo, Japan

Yoshio Sakagawa