Coin locking system for baths - has special coin with characteristic marks on both sides read by lock which compares insertion time with return time

摘要

The lock is for baths, reading rooms etc., and it reads codes on both sides of the coin in the form of concentric grooves. The number of grooves (20) and/or their distance from the centre of the coin is on the one side (7') different from those on its other side (7"). One coin side (7') has an additional recess (20') tested in the lock for determination of the coin side. The lock stores the time of the coin insertion, together with its coding, and when it returns the coin, it compares the stored insertion time with the return time.