Vibrational energy harvester device

A vibrational energy harvester device capable of vibrating in a vibration direction by an externally supplied vibrational energy, comprising:

• a movable part having a first surface along the vibration direction;
• and
• a fixed part which has a second surface opposed through a gap to the first surface and is positionally fixed to allow the movable part to vibrate in the vibration direction, wherein
• the first surface of the movable part and the second surface of the fixed part are provided with a plurality of recessed portions and salients which are disposed alternately in the vibration direction,
• an electret film is formed on at least one of the fixed part and the movable part,
• a force factor as an electromechanical conversion factor having a value corresponding to the gap between the first surface of the movable part and the second surface of the fixed part increases when a vibration amplitude of the movable part increases,
• the recessed portions and the salients formed on the first surface of the movable part and the second surface of the fixed part are grouped into a first group and a second group which have array pitch phases different to each other in the vibration direction, and
• the second group comprises the salients which are not overlapped in a direction orthogonal to the vibration direction between the movable part and the fixed part, when the first group comprises the salients which are overlapped in a direction orthogonal to the vibration direction and are opposed to each other between the movable part and the fixed part.