To provide an electret sheet having high piezoelectricity.
In an electret sheet 1 according to the present invention, two synthetic resin sheets 2, 3 with different compression elasticity moduli are integrally laminated. When a stress is applied to the electret sheet for compressing it in its thickness direction, the synthetic resin sheet with a lower compression elasticity modulus of the two synthetic resin sheets is further compressed in the thickness direction, while the synthetic resin sheet with a higher compression elasticity modulus is not compressed in the thickness direction as much as the synthetic resin sheet with the lower compression elasticity modulus. Accordingly, when a compression force is applied to the electret sheet of the present invention in the thickness direction, the synthetic resin sheet with the higher compression elasticity modulus plays a role for relatively keeping a shape of the electret sheet, and the synthetic resin sheet with the lower compression elasticity modulus is relatively significantly deformed by the compression force.
MURAOKA HITOMI
OKABAYASHI TAKAZUMI
KOBAYASHI SHUNICHI
| JP2007145960A | 2007-06-14 | |||
| JP2010089494A | 2010-04-22 |