| 摘要 |
PURPOSE:To enable the detection of the reflectivity of a developer at a high level by disposing a detecting window oppositely to a developing roll, cleaning said window by the earing part when the magnetic pole part of a magnet roll passes said window, and spacing the developer layer from the detecting window in the intermediate part. CONSTITUTION:The light emitted from a light source 13 passes an aperture 15a, transmits a transparent plate 16, and is irradiated to a developer 20, by which said light is absorbed or reflected. Part of said light arrives at a photodetector 14 to detect the reflectivity of the developer. The distance between the plate 16 and the developer 20 is so set that the ear of the developer contacts with the plate 16 when the earing part of the developer layer passes said plate and that the ear does not contact with the plate when the non-earing intermediate part passes said plate. A high level signal is the detection output at the time when the layer part where the developer in the intermediate part is made uniform densely passes. Said signal has a high level and contains a less noise component. The detection output generated when the intermediate part passes shows the larger difference in the detection output for the difference in the density of the toner. The detection with higher accuracy is thus accomplished. |
