| 摘要 |
PROBLEM TO BE SOLVED: To provide a development apparatus with high development efficiency in a long-term service under high temperature high humidity environment to low temperature low humidity environment, allowing a high quality image free from density unevenness.SOLUTION: A development apparatus includes: an electrostatic latent image carrier at which an electrostatic latent image is formed, a magnetic toner that develops the electrostatic latent image, a magnetic toner carrier that carries and conveys the magnetic toner, and a regulation member that makes contact with the magnetic toner carrier to regulate the magnetic toner. In the development apparatus, a work function value on a surface of the magnetic toner carrier is a specific value. In the regulation member, a portion making contact with the magnetic toner is made of a specific material. The magnetic toner has negative chargeability, and includes magnetic toner particles including a binder resin and magnetic powder, and inorganic fine powder. Average circularity of the magnetic toner is 0.950 or larger, and a surface tension index of the magnetic toner is a specific value. |
