Patent ID: 7881638

Claim:
A developing apparatus comprising: a first chamber, provided with an opening, for containing a developer; a second chamber for forming a circulating path with said first chamber through the opening; a first feeding member for feeding the developer contained in said first chamber; a second feeding member for feeding the developer contained in said second chamber; and a developer carrying member, provided in said first chamber, for carrying the developer to a developing position in which said developer carrying member opposes an image bearing member, thereby to develop an electrostatic image formed on the image bearing member, wherein at least one of said first feeding member and said second feeding member has a multiple thread screw portion having a number of threads n and a thread pitch P, and wherein said opening opposes the multiple thread screw portion and extends from a most downstream end position of the multiple thread screw portion with respect to the developer feeding direction of the multiple thread screw portion toward an upstream side of the multiple thread screw portion in a length of at least nP.