GB2356983A - Probe assembly for measuring surface resistance - Google Patents

Abstract

A probe assembly for measuring surface resistance comprises a central probe 4 an outer annular concentric probe 2 and an insulating sheath 1 outside the outer contact, the surface area of tip the central probe 2 being equal to that of the outer probe 4 and also equal to the area between the probes. A constant pressure is applies the probe tips to a surface whose surface resistance is to be measured.

Description

2356983 PROBE The invention to be patented is a low Ohm meter specially

designed for testing conductive coatings used in the EMC industry. The acceptable test criteria is a measure of Ohms per square measure or area This is an expanding industry world wide and whilst there are test establishments designed for full product testing and so called coating testers, there has been no universally accepted error free system designed for this purpose. Existing testers can produce a variety of different readings depending on operator pressure, and by their design there is always leakage around the test area The new Probe operates with a constant test pressure which satisfies all existing requirements. It can be operated as a hand held tool, be bench mounted or even installed to control quality and material usage on automatic robotically operated production lines.

THEINVENTION.

The new invention in the probe meter is contained in the working head which is of a circular design. The external layer or coating is of a non conductive material to prevent any current leakage (1). Tightly fitted to the inside of this cover is a band of conductive material such as brass (2) which acts as a receiver for the applied charge. Next there is an air gap (3) which surrounds a second rod of conductive material (4) through which the charge is introduced. When not in use both 2 and 4 protrude out from the non conductive material.

The main point of the invention is that contact areas of 2, 3 and 4 are equal. A calibrated load is applied to the internal ends of 2 and 4 by either mechanical or dynamically means. This load is pre-set during manufacture to generate the trial parameters for each particular product range. The outer ridged non conductive layer prevents excess pressure being applied be any external agent. This produces a standard piece of testing equipment which can be hand bench or automatically applied.

2- There already exists a large number of hand or bench test meters which can be adapted to accommodate the tool head. The most suitable of these will be chosen and the LCD unit will be modified to show simply Pass or Fail. A two single sound generator will also be added to correspond to the above signals.

It is anticipated that any meter would also be able to simultaneously test the product for continuity between any predetermined points enabling one meter perform both tests.

In a fully automated system the fail signal would be linked to any coding system being used resulting in that any component failing to comply would not be coded and could be removed from any subsequent operational line.

Each system will be sealed and re-calibrated at source as required.

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Claims (6)

1. The design and operation of the circular head is unique.

2. The tension parameters are pre-set during manufacture to conform to the product specification required test ranges.

3. The system eliminates operator error.

4. It is independent of product shape or size.

5. It can be used either hand held, bench mounted or incorporated into a fully automatic operating system used with custom designed software.

6. It is independent of the coating materials and can be set to test all current and projected future materials.