Patent ID: 7501741

Claim:
A driving device for moving a movable structure, comprising: a piezoelectric element, having first and second ends, for expansion or contraction to shift in response to a drive signal; a drive shaft, engaged with an engageable portion of said movable structure by frictional coupling, having first and second axial ends, for shifting together with said piezoelectric element by contact between said first end and said first axial end, to move said movable structure axially in a drive shaft direction upon expansion and contraction of said piezoelectric element with a difference between expanding contracting speeds of said piezoelectric element; a retaining frame, including: a first support portion, provided with said second end secured thereto, for supporting said piezoelectric element in a cantilever manner; a second support portion, provided with said second axial end secured thereto, for supporting said drive shaft; and a biasing structure for biasing said drive shaft to press said first axial end on said first end of said piezoelectric element, said biasing structure being attached to said retaining frame; wherein said second support portion also constitutes said biasing structure and has lower rigidity than rigidity of said first support portion.