DENSITOMETER MEASURING MARKING PARTICLE CONCENTRATION ON PHOTOSENSITIVE BODY HAVING CORRECTION FACTOR ADAPTED TO CHANGING ENVIRONMENTAL CONDITION AND FLUCTUATION BETWEEN DEVICE

摘要

PURPOSE: To accurately measure and display the density or marking particles of toner or the like stuck to surfaces of a photosensitive body and others by a photodetector having a special shape and a microcomputer. CONSTITUTION: A luminous flux emitted from a LED 116 is reflected by both marking particles on a foundation 10 like a photosensitive body and the foundation surface and is made incident on a detector 104. Light reflected by marking particles is isotropically scattered and is made incident on a central detector 106 and a peripheral detector 108 with a uniform surface density. Meanwhile, specularly reflected light from the foundation is made incident on the central detector 106 as a narrow luminous flux as it is in accordance with Snell's law. Areas of the central detector 106 and the peripheral detector 108 are equalized and the difference in output current is taken to obtain the intensity of specularly reflected light from the foundation. The output current proportional to the density of marking particles of the peripheral detector 108 is multiplied by a correction coefficient determined by the classification of marking particles. These data are processed by the microcomputer in accordance with a model of the reflection process to obtain an accurate density of marking particles.