Pressure sensor having a piezoelectric vibrator with concencentric circular electrodes

摘要

A pressure sensor includes a vibrator having a diaphragm valve for detecting pressure. First and second circular piezoelectric bodies are located on a respective one of the two principal planes of the diaphragm valve. On one principal plane of the first piezoelectric body, a first circular electrode is located and a second hollow circular electrode is located so as to surround the first electrode. On one principal plane of the second piezoelectric body, a third circular electrode is located so as to oppose the first electrode and a fourth hollow circular electrode is located so as to surround the third electrode and to oppose to the second electrode. In the diaphragm valve, an inside circular portion of the vibrator interposed between the first electrode and the third electrode and an outside circular portion of the vibrator interposed between the second electrode and the fourth electrode vibrate radially so as to expand and contract in opposite directions.