Biaxial microelectromechanical mirror device with piezoelectric actuation

A device comprising a microelectromechanical mirror device, the microelectromechanical mirror device comprising:

• a fixed structure defining an external frame which internally delimits a cavity;
• an internal frame arranged in the cavity and internally defining a window;
• a tiltable structure carrying a reflective surface having a main extension in a horizontal plane, arranged inside the window and elastically coupled to the internal frame by first and second coupling elastic elements;
• and
• an actuation structure coupled to the internal frame and configured to cause rotation, in a decoupled manner, of the tiltable structure around a first rotation axis and around a second rotation axis orthogonal to each other and belonging to said horizontal plane;
• wherein said actuation structure comprises:
• at least a first pair of driving arms elastically coupled to the internal frame and carrying respective piezoelectric material regions configured to be biased to cause a rotation of the tiltable structure around said first rotation axis;
• a further pair of driving arms carrying respective piezoelectric material regions configured to be biased to cause a rotation of the tiltable structure around said second rotation axis, the driving arms of said further pair of driving arms extending between an interior perimeter surface of said fixed structure and an exterior perimeter surface of said internal frame to which they are elastically coupled by first and second suspension elastic elements yielding to torsion around the first rotation axis;
• a second pair of driving arms arranged symmetrically to the first pair of driving arms with respect to said second rotation axis;
• and
• wherein the driving arms of said second pair carry respective piezoelectric material regions and are elastically coupled to the tiltable structure on opposite sides and in proximity to the first rotation axis, by respective elastic elements, yielding to torsion around said first rotation axis.