DEVICE FOR MEASURING PERMITTIVITY OF MATERIALS

• US 3,694,742 A
• Filed: 07/15/1970
• Issued: 09/26/1972
• Est. Priority Date: 07/15/1970
• Status: Expired due to Term

• Current Assignee: Erik Ernestovich Klotinish, Imant Gustovich Matis, Karlis Alfredovich Bergmanis
• Original Assignee: Erik Ernestovich Klotinish, Imant Gustovich Matis, Karlis Alfredovich Bergmanis
• Inventors: Bergmanis, Karlis Alfredovich, Klotinish, Erik Ernestovich, Matis, Imant Gustovich
• Primary Examiner(s): Smith, Alfred E.
• Application Number:
  US05/055,025
• Time in Patent Office: 804 Days
• Field of Search: 324/61,61TI
• US Class Current: 324/663
• CPC Class Codes: G01N 27/228 Circuits therefor measuring capacitance per se G01R27/26

Abstract

A device for measuring permittivity of materials on the basis of at least two different measured capacitance values of a capacitor connected to the material being tested and to a measuring oscillator the output of which is coupled to the input of a frequency meter in the form of a series combination of a switch and a pulse counter with a resetting unit, said capacitor being formed by at least two main electrodes permanently connected to the input of said measuring oscillator, and one additional electrode which is alternately connected by a changeover switch to one of said main electrodes in the course of measurement, while said resetting unit is connected to said pulse counter in the form of a reversible counter by an on-off switch actuated synchronously with said switch of the measured capacitor electrodes, the direction of counting of said reversible counter being determined by the position of said changeover switch of the measured capacitor electrodes.

Claims

1. A device for measuring permittivity of a material, comprising first and second electrodes to be applied to said material to measure a capacitance formed thereby;

a measuring oscillator coupled to said first and second electrodes to measure the capacitance formed thereby;

a third electrode to be applied to said materials, said third electrode being identical with and additional to said first and second electrodes;

a changeover switch means operable between first and second positions to respectively connect said additional electrode electrically in parallel with said first and second electrodes during measurement; and

means connected to the oscillator output to measure the difference between a first value of capacitance measured in said first position of said changeover switch means, said first value of capacitance being that existing between the electrically paralleled first and third electrodes, and said second electrode, and a second value of capacitance measured in said second position of said changeover switch means between the first electrode and electrically paralleled second and third electrodes, whereby the permittivity of the material to be measured is computed from the difference between the first and second measured values of capacitance to eliminate any errors due to improper contact of the electrodes with the material.

2. The device as claimed in claim 1, wherein said means connected to the oscillator output comprises in series connection with said measuring oscillator a switch, a reversible pulse counter and a re-setting unit connected through a second change-over switch, the device including means to display the measured difference between the first and second values of capacitance to indicate permittivity of the material in a digital form.