Electro-mechanical transducer, an electro-mechanical converter, and manufacturing methods of the same

An electro-mechanical transducer comprising:

• a vibrating electrode having a flat vibration surface under no load condition;
• an electret layer facing to the vibrating electrode;
• an electret-insulating layer joined to a top surface of the electret layer;
• and
• a back electrode in contact with a bottom surface of the electret layer,
• wherein a microgap between ten nanometers and 100 micrometers is established between the vibrating electrode and the electret-insulating layer, and a central line average roughness Ra of the vibrating electrode, including a bending under a loaded condition, is 1/10 or less of a gap width measured between a bottom surface of the vibrating electrode and the top surface of the electret layer.

An electro-mechanical transducer comprising:

• a vibrating electrode having a flat vibration surface under no load condition;
• a vibrating-plate-insulating layer disposed at a bottom surface of the vibrating electrode;
• an electret layer facing to the vibrating electrode;
• an electret-insulating layer joined to a top surface of the electret layer;
• and
• a back electrode in contact with a bottom surface of the electret layer,
• wherein a microgap between ten nanometers and 100 micrometers is established between the vibrating-plate-insulating layer and the electret-insulating layer, and a central line average roughness Ra of the vibrating electrode, including a bending under a loaded condition, is 1/10 or less of a gap width measured between the bottom surface of the vibrating electrode and the top surface of the electret layer.