| 摘要 |
PURPOSE:To detect a concn. of a toner by placing a strain gauge on a trimmer member in a developing device, and detecting electrically a deformation quantity formed vertically, when the trimmer member scrapes a developer adhering to the surface of a developing roll in order to keep it constant. CONSTITUTION:When a developer adhering to the surface of a developing roll is made constant, a trimmer member 5 is subjected to a vertical deformation by the developer. Its deformation quantity is determined by a quantity of the developer and the quantity of the developer is determined by a toner concn. Accordingly, a strain gauge 7 is placed in a suitable place of the trimmer member 5, the deformation quantity of the trimmer member 5 is detected by the strain gauge 7, and when its output is compared with a reference voltage corresponding to a toner concn. set in advance, the toner concn. in the developer can be detected immediately before developing an electrostatic latent image formed on the surface of a photosensitive body 6. In this way, a toner can be replenished exactly to a toner box, and a copy image quality can be stabilized. |
