| 摘要 |
PURPOSE:To permit formation of a developer concn. detector to a smaller size without impairing exact developer concn. detection and the goodness of light quantity efficiency by setting the plane of an optical axis inclusive of the optical axis of projected light and the optical axis of reflected light in such a manner that said plane has an inclination with the plane perpendicular to a transparent window member. CONSTITUTION:The developer concn. detector 25 is provided with the inclination to the plane O of the optical axis inclusive of the optical axis of the projected light projected from a light emitting element means 31 toward a developing sleeve 13 and the optical axis of the reflected light from the developer sticking to the outside peripheral face of the sleeve 13 as received by a light emitting element sensor means 32 in such a manner that said plane does not coincide with the perpendicular plane Y with respect to the plane X inclusive of the tangent in the outside circumferential part of the sleeve 13 at the intersected point of the plane O and the outside peripheral face of the sleeve 13. The transparent window member 34 is mounted to a control blade 15 so as to be approximately paralleled with the plane X inclusive of the tangent. The impairment of the exact developer concn. detection by the specular reflected light generated in the transparent window member and the impairment of the goodness of the light quantity efficiency are thereby obviated and the formation of the developer concn. detecting means to the smaller size is permitted. |
