Electronic apparatus for testing moving coins employing successive time

Abstract

An improved method and apparatus for testing coins, metallic credit tokens and similar objects, capable of determining both type or denomination and genuineness thereof, utilize the effect upon the electrical impedance of a sensing component from the presence of an object under test in physical proximity to such component and the effect upon the direct current time constant of an electrical circuit containing such component from the influence of presence of such object upon the effective electrical impedance of such component, and employ a novel testing technique primarily involving determining whether or not a direct current voltage output from such circuit has risen to within a predetermined range of voltage level thereof in time coincidence with an interval of test enablement occurring a predetermined period of time, characteristic of acceptable objects of the particular kind being tested for, after an initial direct current energization of such circuit. Thus, dependence upon direct object-to-object comparisons, sensing of frequencies or other alternating current parameters, and even direct quantitative measurement of impedance values, all of which are difficult or expensive to carry out reliably, are avoided; and, since the influence of the object under test need be detected only in terms of comparative sensing of a time dependent direct current voltage level for conformity with a predetermined level range, the only really critical quantitative measurement or sensing required by the improved testing technique relates merely to time parameters, which can conveniently be accomplished with high precision and reliability through the use of relatively simple and economical apparatus. The essentially time oriented nature of the method advantageously permits its preferred implementation predominantly with digital time reference base generating and coincidence logic type apparatus to provide the mentioned precision and reliability in small space and with modest power requirements. The preferred form of sensing component is simply an inductance coil. The method and apparatus desirably permit the testing to be accomplished while the coin or other object is continuously moving along a test path, such as while rolling down a ramp under the influence of gravity. The preferred form of apparatus also includes features providing great convenience and versatility in readily adapting or adjusting the same for the testing of different types and denominations of domestic and foreign coins or the like.