The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 20, 1976
Filed:
Jul. 17, 1974
James A Baer, Menlo Park, CA (US);
Charles B Clark, Los Altos, CA (US);
Louis F Schaefer, Palo Alto, CA (US);
Savin Business Machines Corporation, Valhalla, NY (US);
Abstract
A toner concentration detecting and toner replenishing system for use in an electrostatic copier having a magnetic brush which carries dry developer comprising a mixture of ferromagnetic carrier particles and toner particles into contact with the surface of a photoconductor upon which a latent electrostatic image has been formed, in which system a quantity of developer is removed from the magnetic brush after development of the image and the brush leaves the surface. The removed developer is directed into a dielectric tube having a restricted outlet which inhibits unstable flow through the tube so that developer in the tube determines the inductance of a coil surrounding the tube. The coil is one element of the tuned circuit of a sensing oscillator, the output frequency of which is compared with that of a tunable reference oscillator to provide a frequency difference signal which is a measure of the relative proportion of toner to carrier in the developer. This frequency difference signal is employed to actuate a toner replenishing system to feed toner from the supply to the developer supply as required to maintain the toner concentration substantially constant.