| 摘要 |
PROBLEM TO BE SOLVED: To provide a gas sensor for accurately detecting gas concentration even under a high temperature. SOLUTION: The gas sensor 10 comprises a measuring chamber 28, where gas GS flows in; and an element body 40 for detection facing the measuring chamber 28. The element body 40 for detection has an element case 42, where a protective film 48 is adhered to the bottom surface. In the element case 42, an acoustic matching board 50 nearly in a cylindrical shape and an ultrasonic element 51 are accommodated in a state being buried in a packed bed 99. Two recesses 94, 95 are formed at the packed bed 99 located at the upper position (in a direction opposite to the acoustic matching board 50 or the protective film 48) in a piezoelectric element 51. COPYRIGHT: (C)2004,JPO&NCIPI
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