Timepieces, usually worn on the wrist, that are powered with a "resonance drive," in which a tiny tuning fork driven electrically provides the motive power. First produced in 1953, the resonance drive type, properly called an electronic watch maintains accuracy since it operates at a frequency higher than that customarily used with balance-type watches. When the battery is too weak to operate the tuning fork, the watch simply stops, without deterioration. Power is provided by miniature high-energy-density batteries.
