Apparatus and method for measurement of the ratio of toner particle electrostatic charge to toner particle mass in electrostatographic devices
Apparatus for detecting a residual quantity of toner
Apparatus for sensing deposition of a thin film layer of a material
Method and apparatus for controlling the thickness of developer on an applicator, such as a magnetic brush, in electrostatic reproduction
Apparatus for developing electrostatic latent image
Image forming apparatus for forming a visual image in accordance with image signals
Developing apparatus Patent #: 4646679
ApplicationNo. 546983 filed on 07/02/1990
US Classes:399/61, Detection of toner in developing unit118/690, During application399/55Bias control
ExaminersPrimary: Grimley, A. T.
Assistant: Beatty, Robert
Attorney, Agent or Firm
International ClassG03G 021/00
AbstractIn electrostatographic apparatus, the ratio of toner particle electrostatic charge-to-toner particle mass and the development rate are determined by providing a piezo device positioned to interact with toner particles. The device is periodically electrically biased to attract toner particles, and the frequency shift of the piezo device due to the mass of attracted toner particles is detected. The electrostatic charge buildup on the electrode due to the attracted toner particles is detected to determine the mass of toner. The potential on the device may be changed periodically from a potential which attracts toner to a potential which repels toner to clean the device.