Konica Minolta Business Technologies, Inc.

Yuusuke Okuno

Toru Hayase

Tomo Kitada

Ichiro Demizu

Kentaro Katori

Kuniya Matsuura

Kanji Nakayama

Tomohiro Kato

Yohei Nakade

Tetsuo Sano

Yoshikazu Aoki

Wataru Watanabe

Takuya Okada

Narutaka Yoshida

Noritoshi Hagimoto

Toshiya Aoki

Hiroshi Murasaki

Hiromasa Ueno

Shigeki Yamamoto

Developing device supplying developer to developing roller, while causing developer to circulate in passage including first and second conveying passages in parallel, and while ejecting part of developer to outside via ejection passage formed as extension of first conveying passage on downstream side in developer conveying direction, developing roller being provided along first conveying passage. Developing device includes: first communication path provided as branch of first conveying passage on downstream side, allowing first passage to communicate with second passage; first conveying part conveying developer in first passage toward first communication path; and entrance allowance unit allowing developer to enter ejection passage from first passage depending on pressure of developer in first passage, first conveying part including main and sub-conveying parts, main conveying part being provided in region corresponding to roller, sub-conveying part, provided downstream of main conveying part, conveying smaller amount of developer per unit time than main conveying part.

Developing device and image forming apparatus

A trickle-type developing device comprising: a stirring and conveying tank provided with stirring and conveying screws that circulate the developer; a discharge member via which a part of the developer is conveyed from the tank to a discharge opening through which the developer is discharged, the discharge opening being provided in the discharge member; and a reverse flow generating screw provided inside a portion of the discharge member, sharing one of rotation shafts of the stirring and conveying screws, and pushing back a part of the developer, wherein the portion has a reduced-radius part and in a cross section thereof perpendicular to an axial direction of the one of rotation shafts, an inner radius of the portion is smaller in the reduced-radius part than in the remaining part, the reduced-radius part being located in a lower part of the portion with respect to a vertical direction of the portion.

A developing device develops a latent image on an image carrier by using a developer. The device includes a developer carrier that faces the image carrier and is configured to rotate while magnetically holding developer on its outer circumferential surface. The device also includes a magnetic member elongated along a rotational direction of the developer carrier to form a gap that surrounds the outer circumferential surface. The magnetic member overlaps an end of a developing region in a direction of a rotational axis of the developer carrier, when viewed from a direction perpendicular to the rotational axis. When a side of the magnetic member close to a center of the developer carrier is divided into first and second sides and located downstream and upstream in the rotational direction, respectively, the first side is set back further from the center than a position where the first and second sides meet.

Developing device, imaging unit and image forming apparatus

Developing bias is set as follows. An electric field intensity between a developing roller and a photoconductor is set to cause normally-charged toner to fly in an image area and not to cause the toner to fly in a background area. Thus, the normally-charged toner does not fly in the background area. The normally-charged toner caused to fly is therefore unlikely to flick low-charged toner and oppositely-charged toner. The low-charged toner and the oppositely-charged toner will not adhere to the background area and cause image fogging. Accordingly, an image forming apparatus can be provided to prevent the low-charged toner and the oppositely-charged toner from adhering to the background area of an electrostatic latent image on the photoconductor and to avoid the occurrence of image fogging in the background area on a printed material.

Image forming apparatus and image forming method for adjusting developing bias

The present invention provides a developing device which is capable of suppressing the generation of a fogging phenomenon and deposition of carrier particles to an electrostatic latent image carrier and developing the electrostatic latent image efficiently, the device includes a development sleeve and a magnet body onto which the sleeve is fitted, and using a two-component developer. An angular position which indicates the peak value of the magnetic flux density in the normal direction produced by a development pole of the magnet body is shifted downstream from the center position of the development pole in the direction of movement of the surface of a photosensitive member in a development region. The present invention also provides an image forming apparatus which can form high-quality images with reduced noise such as fogging by mounting the developing device.

In case new and old toners may be mixed, a developing bias is set as follows. The time is first clocked. The number of times toner is replenished from a hopper into a buffer for a clocked period is counted. If a replenishment amount per clock time is a threshold value or higher, considering that new and old toners are mixed, the setting of the developing bias is changed. An electric field intensity between a developing roller and a photoconductor is set to cause normally-charged toner to fly in an image area but not to fly in a background area. No image fogging is therefore generated in the background area. Thus, an image forming apparatus and method capable of preventing low-charged toner and oppositely-charged toner generated by mixing of new and old toners from adhering to the background area of an electrostatic latent image on the photoconductor, thereby avoiding generation of image fogging.

Image forming apparatus and image forming method

The development apparatus that develops an electrostatic latent image formed on an image carrier comprises: a developer roller operable to carry toner on a circumferential surface thereof and develop the electrostatic latent image using the toner; a supply roller operable to perform toner supply to the developer roller; a voltage applier operable to apply a bias voltage Vto the developer roller and apply a bias voltage Vto the supply roller; and a controller operable to control the voltage applier in a toner compulsive consumption mode so that a value obtained by subtracting an average Sof the bias voltage Vper unit time from an average Sof the bias voltage Vper unit time indicates the same polarity as a normal charging polarity of the toner. Here, the toner compulsive consumption mode performs development to compulsively consume the toner carried on the circumferential surface of the developer roller.

Development apparatus, image forming apparatus and image forming method for consuming degraded toner

A developing device has a developer bearing member, a housing adapted to accommodate a developer, and a supply roller adapted to supply the developer within the housing for the developer bearing member. The supply roller has an outer circumferencial foam layer made of resin or rubber. The foam layer has an air permeability of 150-200 ml/cm/s, a hardness of 50-200 N, and an average cell density of 20-40 per 25 mm width.

Image forming apparatus with toner supplying roller

A potential difference between the photoreceptor and the development roller is set at a value at which the normally charged toner on the development roller can be flown toward the photoreceptor in the development phase at the time of compulsorily consuming the toner, and this potential difference is set at a value at which the flown normally charged toner can be returned to the development roller in the recovery phase.

Image forming apparatus with toner discharge method

A developing device has a bearing member that can bear a toner, a storing chamber for storing the toner, a waiting chamber disposed below the storing chamber for receiving the bearing member that can be filled with the toner and a buffer chamber positioned between the storing chamber and the waiting chamber for storing the developer material. A first horizontal connecting path connects upper portions of the storing and buffer chambers, and two second connecting paths connect lower portions of the buffer chamber and the waiting chamber. A feed member feeds toner from the storing chamber through the first connecting path into the buffer chamber. A first conveying member in the buffer chamber conveys the toner from one of the connecting paths to the other of the connecting paths, and a second conveying member in the waiting chamber conveys the toner within the waiting chamber in the opposite direction.

An image forming apparatus has an electrostatic latent image bearing member capable of bearing an electrostatic latent image thereon, and a developer apparatus having a developer material for visualizing the electrostatic latent image into a visualized image. The developer apparatus includes a developer material bearing member, a housing adapted to accommodate a developer material, and a supply roller adapted to supply the developer material within the housing for the developer material bearing member. The supply roller has an outer circumferential foam layer. The foam layer is made of resin foam or rubber foam and has an air permeability of 5 ml/cm/s or less, a density of 50-200 kg/m, and a hysteresis loss ratio of 35-45%.

Growing community of inventors

Toyokawa, Japan

Yuusuke Okuno