Minolta Camera Kabushiki Kaisha

Susumu Sakakibara

Shizuo Yuge

Toshio Yamamoto

Hideya Nishise

Tateki Oka

Takuma Ishikawa

Naoki Toyoshi

Kouji Ito

Masaru Imaizumi

Yuji Hayashi

Katsumi Maeda

Nobuo Kito

A developing device including a rotatable developing sleeve confronting an electrostatic latent image support member, a supply device for supplying developer to a peripheral surface of the developing sleeve, a bristle height regulating member, a device for removing from the peripheral surface of the developing sleeve, the developer having passed through a developing region, a cutoff device for cutting off supply of the developer from the supply device to the developing sleeve, which is retractably projected into a developer supply region defined between the developing sleeve and the supply device and a magnet member provided fixedly in the developing sleeve and having a developing magnetic pole confronting the support member, a first magnetic pole confronting the bristle height regulating member and a second magnetic pole of a polarity identical with that of the first magnetic pole such that the developer is continuously held in an erect state on the developing sleeve by the first and second magnetic poles.

Developing device with retractable cutoff member

A toner supplying device of the present invention has a toner storage tank having a toner supply opening in its bottom for accommodating a toner therein; a first toner transport member disposed within the storage tank and drivingly rotatable for transporting the toner; a second toner transport member disposed within the storage tank in parallel with the first toner transport member and drivingly rotatable for transporting the toner in a direction opposite to the direction of transport by the first toner transport member; and a cover covering the first toner transport member and the toner supply opening, yet only partially covering the first toner transport member. With this device, an excess of toner is prevented from flowing out from the storage tank through the opening since the cover is provided at an intermediate portion of the path of transport of the toner for covering the first toner transport member and the toner supply opening.

Toner supplying device

At least one developing unit of the magnetic brush type is disclosed opposite to an electrostatic latent image carrier, said developing unit having a developing sleeve in which is housed a magnetic roller having a weak-magnetic or non-magnetic portion. The developing unit also has drive means for rotating the magnetic roller and the developing sleeve a specified degree, whereby the magnetic roller is so rotated that its weak-magnetic or non-magnetic portion is allowed to pass a position opposite to a level regulating member, and whereby the developing sleeve is subsequently so rotated until its outer peripheral portion opposite to the weak-magnetic or non-magnetic portion reaches a position opposite to the electrostatic latent image carrier. Thus, a developing powder present on the outer periphery of the developing sleeve is shunted away from a developing zone on the outer periphery. Such shunting of the developing powder is carried out with any of the developing unit other than one selected for developing operation.

Magnetic brush type developing apparatus for development of

A dry process developing apparatus of a type in which, by supplying toner contained in a toner replenishing tank with respect to magnetic carrier magnetically attracted onto an outer peripheral surface of a developing sleeve, a magnetic developing material composed of the magnetic carrier and toner is prepared on the outer peripheral surface of the developing sleeve for developing an electrostatic latent image supported on the surface of an electrostatic latent image support member by the use of this developing material. The developing apparatus includes a space chamber defined between a bristle height restricting member and a front restricting member so as to open towards the outer peripheral surface of the developing sleeve, and preliminarily loaded with the magnetic carrier, and a toner supplying section for supplying the toner with respect to the outer peripheral surface of the developing sleeve at the upstream side of the front restricting member.

Dry process developing apparatus

A toner replenishment control method for a developing material including two kinds of toners triboelectrically chargeable to polarities opposite to each other, which includes the steps of causing the respective toners contained in the developing material to separately adhere to each of first and second surface areas of a detecting member having predetermined potentials, obtaining first and second detecting signals substantially proportional to amounts of the respective toners which have adhered to the first and second surface areas, the first and second detected signals being set to become equal to each other when a mixing ratio of the respective toners in the developing material is set at a standard mixing ratio, relatively comparing the first and second detected signals, and in the presence of a difference therebetween, replenishing either one of the respective toners to the developing material for eliminating the difference.

Method of controlling replenishment of toners

The disclosure is directed to an improved electrostatic latent image developing method in which uneven development arising from simultaneous employment of a magnetic roller rotational driving system and an AC developing bias impressing system is eliminated, without impairing the advantages available from such systems, so as to make it possible to provide developed images of good quality at high density in the application, for example, to an electrophotographic copying apparatus and the like.

Method of developing electrostatic latent images

An improved reversal development method of visualizing an electrostatic latent image through reversal development, including the steps of: forming a magnetic brush around an outer circumferential surface of a developing sleeve by the use of a developer composed of high-resistivity toner having a resistance value of 10.sup.13 .OMEGA.cm or more under an electric field of 10.sup.4 V/cm and a charge amount of 5 to 15 .mu.Q/g per unit mass generated by gaseous discharge; and applying simultaneously an a.c. bias, and a d.c. bias approximately equal to a sum of a potential of an image portion of the electrostatic latent image and a potential of its non-image portion to the magnetic brush.

Growing community of inventors

Toyohashi, Japan

Susumu Sakakibara