Patent ID: 7567773

Claim:
A developer vessel comprising: a developing agent supporter that supports a developing agent containing a toner and a carrier; a second developing agent holding chamber that holds the developing agent supplied to the developing agent supporter; a first developing agent holding chamber that holds the developing agent, the first developing agent holding chamber being housed adjacent to the second developing agent holding chamber; a first partition that divides the first and the second developing agent holding chambers, the first partition having a second opening portion and a third opening portion; a first carrying member and a second carrying member, both of which cause the developing agent held in the first developing agent holding chamber and the second developing agent holding chamber to circulate between the first developing agent holding chamber and the second developing agent holding chamber by allowing the developing agent to pass through the second and the third opening portions; a toner holding chamber that holds the toner supplied to the first developing agent holding chamber, the toner holding chamber being housed adjacent to the first developing agent holding chamber, and arranged in a position facing the second developing agent holding chamber through the first developing agent holding chamber, and; a second partition that divides the first developing agent holding chamber and the toner holding chamber, the second partition having a first opening portion through which the toner supplied from the toner holding chamber to the first developing agent holding chamber passes, the second opening portion arranged towards an upstream end portion of the first developing agent holding chamber in a direction in which the developing agent is carried by the first carrying member and the third opening portion arranged towards a downstream end portion of the first developing agent holding chamber in a direction in which the developing agent is carried by the first carrying member, the first opening portion arranged between the second opening portion and the upstream end of the first developing agent holding chamber in a direction in which the developing agent is carried by the first carrying member; the developer vessel being used in a rotation type development apparatus in which a plurality of developing agent supporters are arranged along a circumference of a rotatable body, and development is carried out by causing the rotatable body to rotate such that one of the plurality of developing agent supporters is moved to a position facing an image carrier.