Optical measurements of toner motion in a development nip

In single component development, a monolayer of charged toner is put on a d onor roll and presented to a charged image on a photoreceptor. The donor an d photoreceptor can either be put in contact or development can occur acros s a small gap between the photoreceptor and the donor roll. When there is a gap, one can directly observe the toners traversing the gap optically. We have designed a system where we capture the image of the transmitted light through the development gap with a high resolution CCD camera. From these d igital images, we can quantitatively extract the toner density toner size a nd toner velocity as the particles traverse the nip. Using time delay photo graphy with microsecond resolution we measure the response of the cloud to incoming images. Using an organic film, which can form a permanent latent i mage, we are able to capture images of fine line development. Quantifying t he density and motion of toners in single component development across a ga p has allowed us to generate accurate physical models of the development pr ocess.