Terminal Protective Case and Audio Playback System

An audio playback system, comprising:

• a terminal, comprising:
• a drive circuit;
• and
• a second conductive contact electrically connected to the drive circuit;
• and
• a terminal protective case, the terminal protective case comprising:
• a housing, comprising a main body part and a fastening frame part;
• a diaphragm;
• a piezoelectric sheet;
• and
• a first conductive contact;
• wherein a side of the fastening frame part is fastened to a periphery of the main body part, and wherein the fastening frame part and the main body part jointly enclose an accommodating groove;
• wherein the diaphragm is located within the main body part, wherein the piezoelectric sheet is fastened to the diaphragm, wherein a front cavity is on a side of the diaphragm, wherein a sound outlet hole is disposed on the main body part, and wherein the sound outlet hole connects the front cavity to the outside of the main body part;
• and
• wherein the first conductive contact is fastened to at least one of the fastening frame part the main body part and projects from the accommodating groove, and wherein the first conductive contact is electrically connected to the piezoelectric sheet;
• and
• wherein the terminal is disposed in the accommodating groove, wherein the second conductive contact abuts the first conductive contact, wherein the drive circuit is configured to convert an audio signal into a drive signal and to transmit the drive signal to the piezoelectric sheet through the second conductive contact and the first conductive contact, wherein transmitting the drive signal to the piezoelectric sheet drive the piezoelectric sheet to cause the diaphragm to vibrate.