US Patent 9340153 Warning alarm apparatus and method for steering wheel

A warning alarm apparatus for a steering wheel includes at least one piezoelectric transducer provided in the rim of the steering wheel; a current supplier; one or more sensors, equipped in the steering wheel or a motor vehicle, sense a dangerous factor; and a controller that determines whether a sensor value sensed by the sensor is included in a warning alarm range, and controls operation of the current supplier according to the sensor value.