Sharp Kabushiki Kaisha Corporation

Shinji Imagawa

Syoichiro Yoshiura

Hiroshi Kawano

Masaru Tsuji

Eiichi Kido

Yuhi Yui

Itaru Kawabata

Hiroaki Yoshida

Keizo Fukunaga

Toyokazu Mori

Yoshikazu Kawasaki

Hiroshi Ishii

Masatsugu Nakamura

Takashi Kitagawa

Shunju Anzai

Hideaki Kurimoto

Masaaki Ohtsuki

Koichi Inui

Syunju Anzai

Masahiro Okuyama

A developing device includes a developer tank holding a developer, and a transporting member stirring and transporting the developer. The transporting member includes first and second screws each provided with a rotary shaft having a spiral blade disposed on an outer circumferential face of the rotary shaft. The first and second screws are disposed such that the rotary shafts are parallel to each other. The developer tank includes a first compartment accommodating the first screw, a second compartment accommodating the second screw, a partition separating the first compartment and the second compartment, and a circulation zone. The circulation zone includes an opening in the partition that allows the developer to flow through. The first and second compartments have bottom faces at different heights. A protrusion is formed on a bottom face in the circulation zone.

Developing device and image forming apparatus

A small domain generation section generates a plurality of small domains in a multi-valued image transmitted from an intermediate tone correction section. Each domain is constituted of a plurality of pixels. Counting means counts a signal input value of each pixel. Weighting calculation means corrects each signal input value of the 'pixels subjection to toner quantity equivalent value calculation' with reference to the signal input value of the small domain, and reads out a weighting coefficient from the weighting coefficient table based on the modified signal input value. The weighting calculation means multiplies the signal input value by the coefficient so as to convert the signal input value into a toner quantity equivalent value. Accumulating means calculates toner quantity equivalent values for all of the pixels of the multi-valued image. A total toner quantity equivalent value calculation section determines a total toner quantity equivalent value by accumulating all of the toner quantity equivalent values which are individually calculated each time an image is processed. When the total toner quantity equivalent value reaches a predetermined value, conditions for process control is set. On this account, the present invention achieves an image forming apparatus capable of accurate estimation of toner consumption quantity.

Image forming electrophotography apparatus setting conditions for process control based on a total toner quantity equivalent value

A method for transfer voltage adjustment for use in an image forming apparatus includes forming first and second halftone reference patterns, transferring the halftone reference patterns to a transfer element at respective first and second saturated transfer voltages, calculating first and second amounts of adhering toner on the transfer element, and setting up a saturated transfer voltage based on the first and second transfer voltages, the amounts of adhering toner, and a saturated amount of adhering toner obtained from stored data.

Method for transfer voltage adjustment and image forming apparatus using the same

An image forming apparatus includes: toner supply amount detecting means for detecting a toner supply amount to a developer tank; detecting means for detecting a signal value of each pixel of an image; and toner consumption amount estimating means for estimating a toner consumption amount, based on the signal value. The signal value detected by the detecting means is corrected in accordance with the toner supply amount detected by the toner supply amount detecting means. The toner consumption amount is estimated based on the signal value corrected. This allows the toner consumption amount to be always calculated accurately, regardless of a variation amongst various models, or a variation in a toner consumption characteristic due to aging, using environment, or the like.

Image forming device and toner consumption amount estimating method

A charger performs corona discharge by applying a voltage to a discharging electrode. The charger includes an electrode plate formed in the shape of a panel on the discharging electrode, a plurality of projecting portions disposed in an end portion of the electrode plate, and a plurality of projection groups formed in each of the projecting portions such that the projection groups are adjacent to each other in a thickness direction of the electrode plate.

Charger for performing a corona discharge

A charger charges a recording medium before irradiation of light to form an electrostatic latent image by irradiating light as an optical image onto a surface of the recording medium. The charger includes a discharging electrode having a plurality of projections for generating corona discharge to charge the recording medium surface, a conductive shield case having an opening face opposite to the recording medium and opposed to the discharging electrode, a holding member for holding the discharging electrode in the shield case in a state in which the discharging electrode is electrically insulated from the shield case, a conductive grid electrode electrically insulated and held between the discharging electrode and the recording medium, and a power supplying device for supplying a high voltage for discharge to the discharging electrode and setting a ratio of electric currents flowing through the grid electrode and the shield case such that these electric currents are approximately equal to each other. One form of the charger controllably moves the discharger electrode toward the recording medium for setting the value of the electric currents flowing through the grid electrode and the shield case until they are both equal to a predetermined reference value.

Corona charger for image forming apparatus providing uniform surface

A contact charger includes a photoreceptor having a photosensitive layer formed on a surface of an electrically conductive drum base and a fixed coil connected to the drum base and ground. The contact charger charges the photosensitive layer by making a charge roller in contact with the photosensitive layer while being applied thereto DC voltage from a power supply. With this arrangement, in the case where a pin hole exists on the photosensitive layer, there may have a continuity between the charge roller and the drum base which may results in a sudden increase in current flowing between the drum base and ground. When this happens, however, since self-induced electromotive force, having a direction opposite to the electromotive force of the power supply, is generated by the fixed coil in response to a sudden increase in current, excessive current will not flow between the drum base and ground, thereby eliminating the possibility of a large drop in voltage of the power supply. As a result, the contact charger is always capable of appropriately charging the surface of the photosensitive layer even in the case where a defect such as a pin hole exists on the photosensitive layer.

Excessive current preventing device for the contact charging of a

A page printer for printing a document by a page on receiving printing data sent from an external device. The printer comprises printing engine for performing a printing process based on page data and a page data preparing section for preparing page data on printing data input from the external device. The printer is provided with an external memory for storing prepared page data and control section for alternatively selecting either the external memory or the page data preparing section. The control section supplies the printing engine with page data from selected one of the page data preparing section and the external memory based on the selection.

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Nara, Japan

Shinji Imagawa