| 摘要 |
Apparatus for making a selection from between a plurality of different options such as different products vended from a vending machine including a housing structure having an elongated passageway therein, a wall at one end of the passageway, a device for introducing an acoustic pulse in the passageway at the one end and senors means at the one end for responding to pulses introduced into the passageway and reflected back along the passageway, and a plurality of spaced selection members mounted on the housing each having a wall portion movable between positions extending into the passageway thereat and position not extending into the passageway. The invention may also be used in association with a microprocessor capable of determining the round trip travel time of a pulse introduced into the passageway including the round trip travel time when the pulse is reflected by a fixed opposite end of the passageway for calibration purposes. |
