Abstract: A comb-shaped piezoelectric unit, such as may be used for a mechanical signal source or in a display device for displaying raised letters for reading by blind persons. The piezoelectric unit includes a plurality of strip-shaped drive members extending from a common base part, a first metal electrode layer on each of the drive members with the first metal electrode layers among the drive members being insulated from one another, and a common metal electrode layer formed on the other side of the drive members, connected commonly to all drive members. To construct a display device for the blind, pins are attached to the free ends of each of the drive members, the pins being protrudable through respective holes in a rigid plate when the corresponding drive members are actuated by applying a voltage thereto.