Patent ID: 7547833

Claim:
A key driving apparatus for driving a key, the apparatus comprising: a first elastically deformable unit configured to receive a first control voltage, the first elastically deformable unit being configured to show elastic deformations of stretch and shrinkage based on a level of the first control voltage, and the first elastically deformable unit being configured to allow the key to be driven by the elastic deformations of stretch and shrinkage of the first elastically deformable unit, the first elastically deformable unit comprising: electrodes configured to receive the first voltage; and an elastically deformable polymer film having a dielectric property, the elastically deformable polymer film being interposed between the electrodes, the elastically deformable polymer film being configured to show elastic deformations of stretch and shrinkage based on the level of the first control voltage, the elastic deformations being such that the elastically deformable polymer is stretched in an in-plane direction and shrunken in a thickness direction at a first level of a control voltage, and that the elastically deformable polymer is shrunken in the in-plane direction and stretched in the thickness direction at a second level of the control voltage.