Canon Kabushiki Kaisha

Takehiro Kojima

Teppei Nagata

Ryota Fujioka

Shota Takami

Takahito Fuse

Yoshiro Tsukada

In an image forming apparatus, in a case where a power of the apparatus is turned from OFF to ON, a rotation drive unit rotationally drives each of a developing roller, a first conductive roller, and a second conductive roller in a state where a liquid developer supplied to a developer container by a supply device has reached a supply position, and a bias application unit applies a bias to each of the developing roller, the first conductive roller, and the second conductive roller after the developing roller rotates at least once, in the state where the liquid developer supplied to the developer container by the supply device has reached the supply position.

Image forming apparatus including a developing device that develops an electrostatic latent image

A developing device includes a rotatable developer carrying member carrying a liquid developer on a carrying surface for developing an electrostatic latent image borne on an image bearing member, and an end portion restricting member, provided in contact with the developer carrying member at an end portion of the developer carrying member with respect its rotational axis direction, for restricting movement of the liquid developer in the rotational axis direction of the developer carrying member. A contact angle of the liquid developer to a side surface of the end portion restricting member on a side where the developer carrying member carries the liquid developer is larger than a contact angle of the liquid developer to the carrying surface of the developer carrying member, and the contact angle of the liquid developer to the side surface of the end portion restricting member is 45&#xb0; or more.

Developing device having liquid developer movement restriction

An image forming apparatus includes a controller for performing a mode, in which an image portion potential is controlled during image formation so that an absolute value of the image portion potential is a first value when a resistance value of a developing roller based on a value of a current flowing between the developing roller and an electroconductive member is smaller than a predetermined value when a predetermined potential difference between the developing roller and the electroconductive member is formed during non-image formation and so that an absolute value of the image portion potential is a second value smaller than the first value when a resistance value of the developing roller based on a value of current flowing between the developing roller and the electroconductive member is not smaller than the predetermined value when the predetermined potential difference between the developing roller and the electroconductive member is formed during non-image formation.

Image forming apparatus

An image forming apparatus includes a control unit configured to execute a stop mode in which, after image forming operation is stopped, a developer bearing member is rotated for a predetermined time with a potential difference between a film forming electrode and a developer bearing member set to zero or smaller than that during image formation, and thereafter, the rotation of the developer bearing member is stopped.

A developing apparatus includes a developer bearing member, a developer container, and a storage tank arranged within the developer container to store liquid developer to be supplied to the developer bearing member. The storage tank includes a first bottom surface including an inclined portion that is inclined downward with respect to a horizontal direction in a rotational axis direction of the developer bearing member, and a discharge port arranged on a lower end of the inclined portion of the first bottom surface. The developer container includes a second bottom surface including an inclined portion that is inclined downward with respect to the horizontal direction toward an opposite direction as the inclined portion of the first bottom surface in the rotational axis direction of the developer bearing member, and a discharge port arranged on a lower end of the inclined portion of the second bottom surface.

Developing apparatus

A developer container is capable of supplying a liquid developer to a portion, of a surface of a cleaning roller, between a cleaning position X and a contact position Y with respect to a rotational direction of the cleaning roller. A free end of a cleaning blade is positioned in a range of 65&#xb0; or more and less than 95&#xb0; as a positive angle of the rotational direction of the cleaning roller when a line passing through a center of the cleaning roller and an upper end portion of the cleaning roller with respect to a direction of gravitation is at 0&#xb0; (reference line G). In this case, the cleaning blade is disposed so that an angle &#x3b1; between a line F perpendicular to a line E connecting the center of the cleaning roller and the free end of the cleaning blade, and the cleaning blade is in a range of 35&#xb0; or more and less than 60&#xb0; .

Developing device with cleaning roller and cleaning blade

An image forming apparatus executes a first obtain mode to obtain a resistance value of a developing roller when a potential difference between the developing roller and an electroconductive roller is generated by a second voltage generator when the developing roller carries a reference liquid developer having a known toner concentration. A second obtain mode is executed to obtain a toner concentration of the liquid developer on a surface of the developing roller based on the obtained resistance value and a detection result when a potential difference between the developing roller and the electroconductive roller is generated by the second voltage generator when the liquid developer is applied to the developing roller. During image formation, the controller controls a first voltage generator based on the obtained toner concentration so the toner concentration of the liquid developer on the surface of the developing roller is a target value.

A developing roller is rotatable while carrying a liquid developer containing toner and a carrier liquid and contains an electroconductive agent, and includes a squeeze roller provided in contact with the developing roller through at least the carrier liquid, a voltage source capable of generating a potential difference between the developing roller and a squeeze roller, and a current detecting sensor for detecting a current passed between the developing roller and the squeeze roller. In addition, a controller controls the voltage source, and a display device outputs information on a lifetime of the developing roller. The controller outputs the information on the lifetime from the display device on the basis of a detection result by the current detecting sensor when a predetermined potential difference is generated between the developing roller and the squeeze roller by the voltage source.

Image forming apparatus having toner concentration detection

A high-density area of a low-reflectance patch image is accurately detected. There is an image forming apparatus that detects the density of a patch image by radiating light from a laser oscillatorand receiving reflected light reflected off the patch image using a line sensor. The density of a black patch imagehaving a low reflectance is detected from the difference between the position at which reflected light from a yellow patch imageis received and the position at which reflected light from a superimposed toner image that is transferred in such a manner that the yellow patch imageis superimposed on the top of the black patch imageis received.

A toner image height measurement apparatus capable of accurately measuring heights of toner images of respective colors with a relatively simple construction and without being affected by toner colors. With motion of an image carrier, there occurs a change in reflection light amount detected by a photodiode of the height measurement apparatus in timing when laser light having been irradiated onto the image carrier starts to be irradiated onto or intercepted by a toner image and in timing when the laser light having been irradiated onto the toner image starts to be irradiated onto the image carrier. Based on a principle that these timings vary according to a toner image height, the height measurement apparatus detects the timing when the reflection light amount changes by a predetermined amount, thereby detecting the toner image height.

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Tokyo, Japan

Takehiro Kojima