Ricoh Company, Ltd.

Fujitsu Corporation

Other

Hachiro Tosaka

Hiroshi Yamashita

Takashi Yamamoto

Osamu Uchinokura

Yoshimichi Katagiri

Motoi Orihara

Masakazu Kinoshita

Masae Nakamura

Tomiaki Ito

Masami Tomita

Toshiki Nanya

Hiroyuki Fushimi

Yuji Natori

Shin-ichi Kuramoto

Satoru Inoue

Masanori Suzuki

Mitsuo Aoki

Akihiro Kotsugai

Yasuo Asahina

Shinichi Kuramoto

Kimitoshi Yamaguchi

Kunihiko Tomita

Tomio Kondou

Kazumi Ohtaki

Fuchio Takeda

Shunichi Chiba

Tomoe Hagiwara

Hitoshi Ueda

Kazuhiko Hamazoe

Yoshihiro Nomura

Toshiyasu Kawabata

Noriaki Ide

Hiroshi Tanaka

A toner for developing an electrostatic latent image, including toner particles each containing a black colorant and a binder resin, wherein the black colorant comprises a metal oxide having a number average particle diameter in the range of 20 to 100 nm in an amount of 10 to 40% by weight based on a total weight of the toner particles.

Black toner, image forming method and image forming apparatus using the toner

In a method for forming a multicolored toner image in accordance with an electrophotographic process, the addition amount of external additives to a non-added toner is 1.5 to 10.0 parts by weight per 100 parts by weight of the non-added toner in each developing step, the aggregation degree of the toner is within the range of 30 to 80%, and the change ratio of the aggregation degree satisfies the relation:0.8&#x2266;(initial aggregation degree/aggregation degree after no-load revolution of developing portion for 20 hours)&#x2266;1.2. According to this method, it becomes possible to form a high-quality color image while a toner always keeps a stable degree of aggregation and a charge amount.

Color image formation method

A toner having a half melting temperature not greater than 115&deg; C. has good fixability without filming, even in an image forming method using a non-contact fixing method; has good fixability and color reproducibility, even in an image forming method reproducing multi-colored images by combining two or more toner layers of different color; has good heat resistance without impairing fixability and color reproducibility; and produces high quality images without impairing fixability and color reproducibility.

Toner, image forming method and apparatus using the toner, and container containing the toner

An image formation process which forms a toner image by the nonmagnetic one-component developing system by bringing an electrically conducting brush impressed with a voltage into contact with a photosensitive material to effect the uniform charging, and forming an electrostatic latent image on the photosensitive material by the exposure to the image-bearing light, wherein the toner that is used as a circularity of from 0.92 to 0.98. The nonmagnetic one-component developing system minimizes irregular electric charging that stems from the use of the electrically conducting brush. This action is obtained even in full-color developing system which effects development many times.

Image formation process and developer used therein

In a method for forming a color image by using a contact type nonmagnetic one-component developing device, a flat sheet-like blade made of a metal flexible member and having a distal end thereof chamfered is used inside the developing device in combination with a toner having a glass transition point of 55 to 70&deg; C. and a weight average particle diameter of 6.0 to 10.0 &mgr;m, and containing up to 20 number % of particles having particle diameters of 5 &mgr;m or below, as a developer. The developing device is simple in construction, can provide high image quality and can, moreover, provide a highly reliable image formation method.

Electrophotographic image formation process and apparatus

An image forming method including a new toner fixing method and toner therefor, wherein the method includes two rollers in which a toner image on an image supporting material is fixed by heating at a nipped section of the rollers, wherein one of the rollers which is a fixing roller contacting the toner image includes a metal cylinder having a thickness of not more than 1.0 mm, and the fixing pressure of the two rollers is not more than 1.4&times;10,Pa, and wherein the toner contains resins including two polyester resins, (A) and (B), and the polyester resin (B) includes discrete domains of the polyester resin (A) which has higher glass transition Tg and higher molecular weight than those of the polyester resin (B) and includes a component insoluble in tetrahydrofuran, and wherein the developed image can be fixed at relative low temperature and in wide temperature range, and the fixed image has excellent image quality and preserving property.

Image forming method and dry toner therefor

A one-component magnetic toner with high resistivity for use in electrophotography for developing latent electrostatic images to visible toner images by contact development, includes a coloring agent, a binder resin, and a magnetic material which contains a bivalent metal and a trivalent iron with the molar ratio of the bivalent metal to the trivalent iron being 1/3 or less.

One-component magnetic toner for use in electrophotography

In a developing device and a dry color toner for color electrophotography. The developing device is provided with a toner conveying member and a toner layer thickness controlling member which is in contact with the toner conveying member. The color toner for developing electrostatic images used in this developing device has the following relation between the number average particle diameter and the volume average particle diameter: ##EQU1## Even after a continuous copying, the developing device and the color toner provide substantially the same image quality as that in the earlier stages of the continuous copying.

Developing device of the type forming thin layer of toner on toner

This invention relates to a toner for developing an electrostatic latent image, which contains a coloring agent, a binder resin and a charge controlling agent as the main components, said charge controlling agent being a metal salt of salicylic acid or derivatives.

Toner for developing electrostatic latent image

A developer comprises a mixture of (a) magnetic toner particles comprising a polymeric material and finely-divided magnetic particles, having an electric resistivity of 10.sup.12 .OMEGA.cm or more, and (b) electroconductive magnetic particles having an electric resistivity of 10.sup.9 .OMEGA.cm or less, a smaller volume mean diameter than that of the magnetic toner particles, with the saturation magnetic moment of the electroconductive magnetic particles being in the range of from 25 emu/g to 75 emu/g, which is larger than the saturation magnetic moment of the magnetic toner particles.

Magnetic developer for developing latent electrostatic images

An electrographic development process wherein an electrically charged developer comprising electrically conductive particles with a volume resistivity of 10.sup.9 .OMEGA.cm or less and toner particles with a volume resistivity of 10.sup.12 .OMEGA.cm or more, with the mixing ratio of the respective particles being from 1:99 to 40:60, is brought into contact, or proximity, with a latent electrostatic image with a polarity opposite to that of the electrically charged developer, and the latent electrostatic image is developed to a visible image by the developer, through the steps of supplying the developer to a developer doner member; forming a developer layer thereon with a thickness ranging from 150 .mu.m to 300 .mu.m; subjecting the developer to charge injection to a potential ranging from -150 V to -500 V; and supplying the developer to a latent electrostatic image bearing member for development of the latent electrostatic image thereon.

Electrographic development process

Growing community of inventors

Shizuoka, Japan

Hachiro Tosaka