Method for Measuring the Resistance of Electrically Conductive Materials

1,186,513. Electro-physical measurement - thickness. GEVAERT-AGFA N.V. May 8, 1967 [May 13, 1966], No.21433/66. Heading G1N. Transverse thickness variations in a moving conductive web or coating e.g. light-sensitive layers on a triacetate base, are determined by measuring the resitance of parallel longitudinal strips. The method of measuring the resistance is by passing the web over A. C energized rollers providing a capacitative coupling to the conductive layer, and measuring the voltage drop across a resistor in series with one of the rollers. As shown one of the rollers 21 is formed with a series of conductive sections 23 each connected to earth through equal resistors, mounted inside the roller together with a stepping switch to connect each section sequentially to a recorder 30, (as illustrated in Fig. 2b not shown). The absolute thickness, instead of relative thickness, may be determined by making the supply voltage dependent on the specific resistance of the coating material Fig.3 (not shown).