A vibration damping device is described that dampens vibration produced during the conversion of rotational motion into reciprocal motion. The weighing mechanism applies a load heavier than a working load to a leaf spring, thereby bending the leaf spring in its thickness direction, and maintains the resulting state for a predetermined hold time. The intensity of backlighting may be varied in accordance with the amount of ambient light illuminating the keypad and above a certain intensity of ambient light the light emitting diode is de-energized to conserve battery power.