A display apparatus includes a display panel displaying an image and a vibration generating device disposed on a rear surface of the display panel to vibrate the display panel. The vibration generating device includes a piezoelectric structure including a first region and a second region, the first region has a vibration characteristic of a first frequency, and the second region has a vibration characteristic of a second frequency which differs from the first frequency.

A display apparatus includes a display panel displaying an image and a vibration generating device disposed on a rear surface of the display panel to vibrate the display panel. The vibration generating device includes a piezoelectric structure including a first region and a second region, the first region has a vibration characteristic of a first frequency, and the second region has a vibration characteristic of a second frequency which differs from the first frequency.

A diaphragm for a piezoelectric micromachined ultrasonic transducer (PMUT) is presented having resonance frequency and bandwidth characteristics which are decoupled from one another into independent variables. Portions of at least the piezoelectric material layer and backside electrode layer are removed in a selected pattern to form structures, such as ribs, in the diaphragm which retains stiffness while reducing overall mass. The patterned structure can be formed by additive, or subtractive, fabrication processes.

A diaphragm for a piezoelectric micromachined ultrasonic transducer (PMUT) is presented having resonance frequency and bandwidth characteristics which are decoupled from one another into independent variables. Portions of at least the piezoelectric material layer and backside electrode layer are removed in a selected pattern to form structures, such as ribs, in the diaphragm which retains stiffness while reducing overall mass. The patterned structure can be formed by additive, or subtractive, fabrication processes.

A piezoelectric element comprising a compound represented by Formula 1, a piezoelectric device including the piezoelectric element, a vibration module including the piezoelectric device, and a display apparatus including the piezoelectric device are provided, where

(1−x)(Li.sub.zNa.sub.0.5-zK.sub.0.5)(Nb.sub.1-ySb.sub.y)O.sub.3.Math.xCaZrO.sub.3  [Formula 1]

where x, y, and z have a range of 0.001≤x≤0.2, a range of 0≤y≤0.5, and a range of 0≤z≤0.2, respectively.

A piezoelectric element comprising a compound represented by Formula 1, a piezoelectric device including the piezoelectric element, a vibration module including the piezoelectric device, and a display apparatus including the piezoelectric device are provided, where

(1−x)(Li.sub.zNa.sub.0.5-zK.sub.0.5)(Nb.sub.1-ySb.sub.y)O.sub.3.Math.xCaZrO.sub.3  [Formula 1]

where x, y, and z have a range of 0.001≤x≤0.2, a range of 0≤y≤0.5, and a range of 0≤z≤0.2, respectively.

A display apparatus includes a display module including a display panel configured to display an image, a supporting member on a rear surface of the display module, and a first vibration generating module including two or more vibration generating devices on the rear surface of the display module to output sounds of different sound bands.

A display apparatus includes a display module including a display panel configured to display an image, a supporting member on a rear surface of the display module, and a first vibration generating module including two or more vibration generating devices on the rear surface of the display module to output sounds of different sound bands.

A piezoelectric element comprising a compound represented by Formula 1, a piezoelectric device including the piezoelectric element, a vibration module including the piezoelectric device, and a display apparatus including the piezoelectric device are provided, where
(1−x)(Li.sub.zNa.sub.0.5-zK.sub.0.5)(Nb.sub.1-ySb.sub.y)O.sub.3.Math.xCaZrO.sub.3  [Formula 1] where x, y, and z have a range of 0.001≤x≤0.2, a range of 0≤y≤0.5, and a range of 0≤z≤0.2, respectively.

A piezoelectric element comprising a compound represented by Formula 1, a piezoelectric device including the piezoelectric element, a vibration module including the piezoelectric device, and a display apparatus including the piezoelectric device are provided, where
(1−x)(Li.sub.zNa.sub.0.5-zK.sub.0.5)(Nb.sub.1-ySb.sub.y)O.sub.3.Math.xCaZrO.sub.3  [Formula 1] where x, y, and z have a range of 0.001≤x≤0.2, a range of 0≤y≤0.5, and a range of 0≤z≤0.2, respectively.