Piezoelectric pump and blood-pressure information measurement device provided therewith

A piezoelectric pump for suctioning a fluid from a suction port of the pump and discharging the suctioned fluid through a discharge port, the piezoelectric pump comprising:

• an actuator including a piezoelectric element and a vibrating sheet to which the piezoelectric element is attached, wherein the actuator is vibrated by the piezoelectric element being resonantly driven;
• a discharge chamber formed on one side of the vibrating sheet, said discharge chamber formed with the discharge port;
• a first diaphragm having therein a first connecting hole through which the fluid flows, wherein the first diaphragm is vibrated with the vibration of the actuator by being positioned on the opposite side of the vibrating sheet;
• a second diaphragm that is vibrated with the vibration of the first diaphragm by being on the opposite side of the first diaphragm from the actuator and positioned opposite the first diaphragm, the second diaphragm having a second connecting hole through which the fluid flows;
• a pump chamber facing the discharge chamber and formed within a space between the actuator and the first diaphragm on said opposite side of the vibrating sheet, wherein
• the pump chamber introduces the fluid thereinto from the suction port positioned on said opposite side of the vibrating sheet via the first connecting hole by the actuator being displaced toward a side opposite to where the first diaphragm is located, and
• the pump chamber delivers the fluid to the discharge chamber by the actuator being displaced toward the side where the first diaphragm is located;
• and
• a backflow preventing portion that prevents the fluid introduced into the pump chamber via the first connecting hole from flowing back toward the suction port via the first connecting hole, wherein the backflow preventing portion is composed of an opposing wall portion provided in a portion of the second diaphragm that opposes the first connecting hole.