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1/5 Second Mechanical Stopwatch

An innovative mechanical stopwatch developed for the 1964 Olympic Games in Tokyo. A heart-shaped cam of the type is usually used for the zero reset of a chronograph. But a heart-shaped cam for this stopwatch was used at the shaft of the balance wheel instead. This unique modification eliminated measurement error by means of preventing from hitting the balance at starting point in order to stop and start at a fixed zero position. The split-time function also enabled simultaneous measurement of two elapsed times.

Name 1/5 Second Mechanical Stopwatch
Time/Period 1964
Additional information This stopwatch brought the hand to a stop just above a scale by automatically rounding off the value when the hand likely came between the gap of the scales. In this way, this eliminated not only individual differences between operators, but also individual differences between units.