Sharp Kabushiki Kaisha Corporation

Kazuma Hinoue

Kiyofumi Morimoto

Mitsuru Tokuyama

Hiroo Naoi

Kohichi Takenouchi

Hideji Saikoh

Motoyuki Itoyama

Masayasu Narimatsu

Kouichi Takenouchi

Takeshi Ohkawa

Tomoki Minamikawa

The image forming apparatus carries out a monitoring operation in which (i) sensor outputs of the magnetic permeability sensor are periodically sampled, (ii) a time period, corresponding to one (1) circulation period which is required for the developer to be circulated once in the circulation carrying path, is evenly divided into a plurality of blocks, and (iii) an average of the sensor outputs in one (1) block time period corresponding to one (1) block is calculated for each of the plurality of blocks; and determines that toner has run short, in a case where the number of times that the averages of the sensor outputs consecutively exceed a threshold, set to be higher than a reference value of the sensor outputs, becomes not less than the number of the plurality of blocks which correspond to the time period corresponding to one (1) circulation period.

Method for judging toner shortage and image forming apparatus

Provided are an image forming apparatus that, when a difference between a developing bias in correcting an image density and a reference developing bias has a value not less than a prescribed value that is set preliminarily, replenishes or consumes a toner forcibly, executes correction of the image density again, and controls the developing bias in such a manner that a toner density is controlled to fall within an appropriate range, and an image forming method using the same. When a difference between a developing bias value after correction of the image density and the reference developing bias becomes larger than the prescribed value to the plus side or the minus side, a toner density control portion performs control to consume or replenish a toner forcibly.

Image forming apparatus, and image forming method

An image forming apparatus prevents printed images from being degraded in image quality due to failure of the toner concentration to fall within a proper range, by correcting the deviations of the amount of toner consumption and the amount of toner supply depending on the individuality of each image forming apparatus and that enables exact identification of the cause of a fault associated with toner concentration, and providing an image forming method using the apparatus. A toner supply device supplies toner to a developing vessel through an opening in accordance with an instruction from a controller. The presence or absence of toner falling is detected based on the variation of the output from a magnetic permeability sensor when toner is supplied. The controller monitors the output voltage level of the magnetic permeability sensor and adjusts the input gain in accordance with the output voltage level to thereby control toner concentration.

Image forming apparatus and image forming method using the same

An image forming apparatus includes a developing device having a toner supply sensor, a toner supply device supplying toner to the developing device, a toner supply controller controlling toner supply from the toner supply device to the developing device based on predetermined conditions, a toner empty determiner determining whether toner is present inside the toner supply device. In the image forming apparatus, the toner supply device includes a storage for recording multiple measured values of toner supply detected by the toner supply sensor, and the toner supply controller corrects the amount of toner supply, based on the moving average of multiple measured values of the amount of toner supply.

Image forming apparatus and toner supply method

The change in an output voltage when a control voltage is changed is calculated, and the change in the control voltage divided by the calculated change in the output voltage is defined as a sensitivity coefficient. The sensitivity coefficient is recalculated for each predetermined time interval or whenever a predetermined condition is satisfied, and the control voltage is corrected based on the recalculated sensitivity coefficient. Example of the predetermined condition include the time of start-up of the apparatus, the time at which the accumulated number of printed sheets reaches a predetermined number, and the time of carrying out process control.

Developing device, image forming apparatus including the same and developing method

In an image forming apparatus comprising a charging section, an exposure section, a developing section, a transfer section, a peeling section, a cleaning section including a cleaning blade, and a fixing section, the cleaning blade is composed by dispersing 15 parts by weight through 33 parts by weight of fluorine resin particulate and secondary particles thereof into 100 parts by weight of a synthetic resin of a base material and, on a surface of the cleaning blade, and a number of the secondary particles of the fluorine resin particulate having a particle diameter of 0.5 &#x3bc;m or more existing in unit area of 100 &#x3bc;mis made to be 50 or less.

Cleaning blade

An image forming apparatus includes a toner image forming section including a developing device having a developer tank for storing a two-component developer, a transfer section, a fixing section, a recording medium feeding section, and a discharging section. The image forming apparatus further includes a toner concentration detecting section for detecting the toner concentration in the developer tank, a printing speed switching section, a toner concentration calculating section for correcting a detection result obtained by the toner concentration detecting section according to a speed of printing to calculate the toner concentration, and a toner replenishment control section for replenishing the toner into the developer tank according to a calculation result by the toner concentration calculating section.

Image forming apparatus with toner concentration sensor

An image forming apparatus capable of performing monochrome printing and color printing in which all the developing units share a single development transformer is constructed such that at the time of monochrome printing the photoreceptor drums for colors are stopped rotating while all the developing units are constantly applied with a high voltage. Further, the cumulative operation time in which the black photoreceptor drum has been operated for monochrome printing is calculated so that the color-printing photoreceptor drums which are stopped during monochrome printing are rotationally driven by a predetermined angle when the cumulative operation time exceeds predetermined fixed time. Thus, the surface of each color-printing photoreceptor drum that is being worn is restored by making the fresh surface of the drum oppose the associated color developing unit, whereby it is possible to prevent occurrence of defects on the surface of each photoreceptor drum.

Image forming apparatus and drive control method of the same

An image forming apparatus that includes: an image forming portion for forming an image in accordance with image data contained in an input command; and a controller for controlling the image forming portion, and is constructed such that the controller includes: a mode switch for switching the image forming portion from a standby mode in which image forming is instantly enabled into a power-saving mode in which power supply to the image forming portion is partially stopped when no subsequent command has been received after a predetermined period elapsed from when image forming portion was operated last; a mode restoring portion for restoring the image forming portion from power-saving mode to standby mode when a subsequent command is received; and an image quality controller for performing image quality control of the image every time a predetermined time elapsed from when the image forming portion was last operated, and the image quality controller starts execution of the image quality control before the mode restoring portion restores the image forming portion from the power-saving mode to the standby mode.

Image forming apparatus with power saving sleep mode

A developing device includes a developing roller and a blade. The developing roller includes: a developing sleeve which rotates while holding two-component developer composed of toner and magnetic carrier on the outer surface having a plurality of grooves extending in parallel to an axis of the rotation; and a magnetic member, provided inside the developing sleeve in such a manner as to be unrotatable, for attracting the two-component developer onto the outer surface of the developing sleeve. The blade is provided outside the rotating sleeve with a gap from the outer surface of the developing sleeve for scraping off a part of the two-component developer on the outer surface of the developing sleeve. Also, the magnetic member includes a magnet for controlling magnetic flux density in the gap to range from 70 mT to 150 mT. This allows preventing image degradation caused by generation of development memory.

Growing community of inventors

Yamatokoriyama, Japan

Kazuma Hinoue