Developing device and image forming apparatus

An image forming apparatus configured to form an image on a recording medium, the image forming apparatus comprising:

• an image carrier on which a latent image is formed;
• a developing device configured to develop the latent image formed on the image carrier with toner;
• and
• a transfer device configured to transfer the image developed by the developing device to a recording medium, wherein
• the developing device comprises:
• a developing case containing the toner and including a circulation path through which air containing the toner flows;
• a mixer accommodated in the developing case and configured to stir the toner to diffuse the toner in the developing case;
• a developing roller partially exposed from the developing case, accommodated in the developing case, including a sleeve rotating along with the movement of the image carrier and a plurality of magnetic pole portions disposed inside the sleeve, and configured to
• hold the toner on the sleeve,
• supply the toner to the image carrier, and
• develop the latent image;
• and
• a magnet disposed apart from the developing roller and facing one of the magnetic pole portions across the sleeve.

A method of processing toner, comprising:

• stirring the toner to diffuse the toner in a circulation path in a developing case of a developing device, the developing device comprising a developing roller partially exposed from the developing case;
• rotating a sleeve along with movement of an image carrier, the sleeve comprising a plurality of magnetic pole portions inside;
• holding the toner on the sleeve;
• supplying the toner to the image carrier;
• developing the latent image formed on the image carrier with toner;
• and
• disposing a magnet in the circulation path apart from the developing roller and facing one of the magnetic pole portions across the sleeve.