| 摘要 |
PURPOSE:To prevent the state where detection is impossible to detect stably reduction of a developer in a developer pool by providing a detecting means, which consists of the combination of a light emitting element and a photodetector, in the position where the light emitting face of the light emitting element and the light receiving face of the photodetector are washed with the flowed-back developer. CONSTITUTION:A one-component developer consisting of magnetic toner particles is attracted to the surface of a magnetic cylinder 2 and is moved in the direction of an arrow opposite to the rotation direction of a magnet roll 3 and is flowed back in a developer pool 1 as shown in the figure by arrows. The developer layer which passes the position of a layer thickness control member 4 develops a latent image of the surface of an image forming body 5, which is rotated in the direction of an arrow, in a development region A. In the region where the developer is flowed back as shown by arrws in the developer pool 1, a detecting means 8 consisting of a light emitting element 6 and a photodetector 7 is so provided that a light emitting face 6a of the light emitting element 6 and a light receiving face 7a of the photodetector 7 face each other in the direction parallel with the axis of the magnetic cylinder 2. Thus, said light emitting face 6a and light receiving face 7a are always washed with the flowed-back developer during development by rotation of the magnetic cylinder 2 and the magnet roll 3. |
