| 摘要 |
<p>An enablement system for vending machines and the like generates an enablement signal, which can be applied to such vending machine, upon reading of a credit card provided with only a single magnetic data track, and the enablement system has merely a one-track capability. The card's track contains, in sequence, a series of warm-up "1" bits, followed by a series of "0" and "1" bits together identifying the card as a valid card, followed by a series of "1" bits each of which signifies one permitted use of the card, followed by a final "0" bit. Each time the card is used, when the final "0" bit reaches the system's reading head, the immediately preceding "1" bit is converted to a "0" bit, this causing the number of such "1" bits to progressively decrease. This permits an inexpensive one-track capability, while yet affording both validity-identification and also number-of-uses updating capability; and furthermore permits both read and write operations during a single unidirectional pass of the card past the system's read-write head. The system lacks expensive card-transport motor systems, and the card is moved manually. The system's read winding applies its card-responsive pulses to an amplifier having automatic gain control, whereby the aforementioned series of warm-up "1" bits on the card, having no data significance, serve to set the amplifier to a gain value compensating for the slower than normal or faster than normal speed of manual insertion or removal of the card, so that the read and write operations can be properly performed despite the absence of a motor-referenced time base and despite the absence of a synthetic time base of the type which conventionally requires the use of synchronizing bits on a separate second track, which the present system successfully avoids.</p> |
