| 摘要 |
<p>A pressure sensor 10 has a sensor chip 14 attached in a package 13 formed with a stem 11 and a cap 12 bonded at open surface sides thereof. On both sides of a diaphragm 14a of the sensor chip, pressures are applied via a measurement pressure introducing tube 11a formed in the stem and a reference pressure introducing tube 12a formed in the cap. Here, a filter 15 is arranged in the reference pressure introducing tube and response to pressure at the reference pressure side is made slow. When the sensor is arranged in a room with a door and a pressure in the room is applied via two introducing tubes, if there is an abrupt change caused by the opening/closing of the door, the pressure change is immediately introduced only at the side of measurement pressure introducing tube with fast response and the differential pressure corresponding to the pressure change is applied on the diaphragm. As the differential pressure is employed, it can be determined whether the door is opened or closed. <IMAGE></p> |
