Savin Business Machines Corporation

E.i. Dupont De Nemours and Company

Mitutoyo Manufacturing Co., Ltd.

James A Baer

Charles B Clark

Louis F Schaefer

Joseph S Eckerle

James R Young

Hugh F Frohbach

Allan F Falcoff

Jan H Kremers

Russell T Wolfram

An electrical device for measuring the dry film thickness of a paint film applied to a conductive coating adhered to a plastic substrate without destroying the film; the device contains the followintg components: a. an electric sensing device of two separate electrodes isolated from each other and positioned in a material capable of conforming to the surface of the film being measured where the sensing device is placed in contact with the surface of the film and measured under a uniform and reproducible pressure; b. a gain and phase measuring device electrically connected to the sensing device for measuring the gain and phase of an alternating current electrical signal passed from one electrode through the film and conductive coating to the second electrode; c. a device electrically associated with the gain and phase measuring device which measures the gain and phase signals of the overall circuit of the two electrodes, the paint film and conductive coating and from the gain and phase signals calculates the thickness of the paint film and the resistance of the conductive coating.

Contact measuring device for determining the dry film thickness of a

A capacitance type displacement measuring instrument is disclosed in which a change in electric capacity between electrodes due to a change in displacement between two members movable relative to each other is detected on the basis of a change in phase of a detection signal and a displacement value between the two members is measured from the change in the capacity. AC signals are successively applied to transmitting electrodes provided on one of the members at a predetermined pitch by a multiplexer and signals induced in transfer electrodes at a predetermined pitch differing from the aforesaid pitch of the transmitting electrodes are received by pickup electrodes provided on the aforesaid one of the members. The relative displacement is detected from a change in phase of a received signal of substantially triangular waveform, which are obtained by the pickup electrode.

Capacitance type displacement measuring instrument

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.

Toner concentration detector

Toner concentration detector for dry powder magnetic brush toning system

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Menlo Park, CA, United States of America

James A Baer