Ricoh Company, Ltd.

Megumi Sakakura

Hajime Oyama

Kiyonori Tsuda

Fumihiro Sasaki

Satoshi Mochizuki

Yasushi Akiba

Seiji Oka

Hidefumi Gohhara

In an image forming apparatus, a developing device has a developing sleeve accommodating a magnet roller therein, and a doctor for regulating the amount of developer to be conveyed to a developing position. When the developing sleeve is rotated, the part of the doctor shaved off by the doctor from the sleeve is moved in a developer storing section to a toner replenishing opening formed in a toner storing section. Then, this part of the developer is returned to the doctor along the surface of the sleeve via the toner replenishing opening. The developer consists of a first developer containing a first carrier and deposited in a layer on the surface of the sleeve, and a second developer containing a second carrier different from the first carrier and stored in the developer storing section in such a manner as to contact the first developer deposited on the sleeve. The first carrier has a higher charging ability than the second carrier. The device does not need a toner replenishing mechanism or a toner concentration sensor and has, therefore, a miniature and inexpensive construction. In addition, the device is applicable even to a high-speed image forming apparatus.

Developing device for an image forming apparatus and toner cartridge

Growing community of inventors

Numazu, Japan

Megumi Sakakura