초록 ▼

A sensor is described, which basically consists of a leadless high sensitivity differential transducer chip which responds to both static and dynamic pressure. Located on the transducer are two sensors. One sensor has a thicker diaphragm and responds to both static and dynamic pressure to produce an

A sensor is described, which basically consists of a leadless high sensitivity differential transducer chip which responds to both static and dynamic pressure. Located on the transducer are two sensors. One sensor has a thicker diaphragm and responds to both static and dynamic pressure to produce an output indicative of essentially static pressure, the static pressure being of a much higher magnitude than dynamic pressure. The other sensor has a thinner diaphragm and has one side or surface responsive to both static and dynamic pressure. The other side of the differential sensor or transducer structure has a long serpentine reference tube coupled to the underneath of the diaphragm. The tube only allows static pressure to be applied on the underside of the diaphragm and because of the natural resonance frequency of the tube, the dynamic pressure is suppressed and does not, in any manner, interface with the sensor or transducer having a thinned diaphragm. Thus, the thinned diaphragm differential unit provides an output which is indicative of the dynamic pressure, as the static pressure applied to both the top and bottom surfaces of the transducer sensor is cancelled.

대표청구항 ▼

What is claimed is: 1. A sensor for measuring low dynamic pressure in the presence of high static pressure comprising: a diaphragm having first and second oppositely disposed surfaces, said diaphragm deflecting according to the magnitude of an applied pressure comprising a low dynamic pressure in t

What is claimed is: 1. A sensor for measuring low dynamic pressure in the presence of high static pressure comprising: a diaphragm having first and second oppositely disposed surfaces, said diaphragm deflecting according to the magnitude of an applied pressure comprising a low dynamic pressure in the presence of a high static pressure, wherein said first surface receives said applied pressure; at least one pressure sensing element located on said diaphragm and operative to provide an output signal substantially proportional to said applied pressure; and a tube member having length L and an inlet and an outlet, said outlet of said tube member opening to said second surface of said diaphragm, and said inlet of said tube member receiving said low dynamic pressure as well as said high static pressure, wherein said tube member filters out said low dynamic pressure with frequencies above the resonant frequency of said tube, while allowing said high static pressure to pass through to said second surface, wherein said sensor provides an output substantially proportional to said low dynamic pressure. 2. The sensor according to claim 1, wherein the resonant frequency of said tube is given by f=c/(4L), where c is speed of sound and L is length of said tube. 3. The sensor according to claim 1, wherein said tube has a resonant frequency less than a frequency associated with said low dynamic pressure. 4. The sensor according to claim 1, wherein said tube comprises a coiled tube. 5. The sensor according to claim 3, wherein said resonant frequency is about 120 Hz. 6. The sensor according to claim 3, wherein said frequency of said low dynamic pressure is about 5000 Hz or greater. 7. The sensor according to claim 1, wherein said sensor is a semiconductor sensor and said pressure sensing element is a piezoresistive element. 8. The sensor according to claim 1, further comprising a stop member operative to stop deflection of said diaphragm for a predetermined force applied to said first surface. 9. The sensor according to claim 7, wherein said semiconductor is silicon. 10. A pressure transducer for measuring an applied pressure having a low dynamic pressure in the presence of a high static pressure, comprising: a housing; first and second sensors in said housing; wherein said first sensor comprises: a first diaphragm receiving said applied pressure, said first diaphragm deflecting substantially proportional to said high static pressure of said applied pressure; and a first pressure sensing element located on said first diaphragm and operative to provide a first output signal substantially proportional to said first diaphragm deflection; wherein said second sensor comprises: a second diaphragm having first and second oppositely disposed surfaces; and a second pressure sensing element located on said second diaphragm; wherein said second diaphragm of said second sensor is thinner than said first diaphragm of said first sensor; and a tube having a length L and extending from said housing, said tube having an outlet end opening to said second surface of the second sensor and having an inlet end receiving said applied pressure; wherein said tube attenuates the low dynamic pressure as a function of its length L, and passes only said high static pressure of said applied pressure to said outlet end of said tube; wherein said second diaphragm of said second sensor receives on said first surface said applied pressure and receives on said second surface only said high static pressure of said applied pressure from said outlet of said tube member; wherein said second diaphragm of said second sensor deflects substantially proportional to said low dynamic pressure of said applied pressure; wherein said second pressure sensing element on said second diaphragm of said second sensor is operative to provide a second output signal substantially proportional to said second diaphragm deflection. 11. The pressure transducer according to claim 10, wherein the resonant frequency of said tube is function of said length L and is given by f=c/(4L), where c is the speed of sound. 12. The pressure transducer according to claim 11, wherein said resonant frequency of said tube is less than a frequency associated with said low dynamic pressure. 13. The pressure transducer according to claim 10, wherein said tube comprises a coiled tube. 14. The pressure transducer according to claim 12, wherein said resonant frequency is about 120 Hz. 15. The pressure transducer according to claim 12, wherein the frequency of said dynamic pressure is about 5000 Hz or greater. 16. The pressure transducer according to claim 11, wherein said first and second sensors are semiconductor sensors and said pressure sensing element is a piezoresistive element. 17. The pressure transducer according to claim 11, wherein said first and second sensors are formed on a common semiconductor wafer. 18. The pressure transducer according to claim 11 further comprising: a stop member associated with said second sensor and operative to stop deflection of said thin diaphragm for a predetermined force applied to said first surface. 19. Apparatus for suppressing high frequency low dynamic pressure, said apparatus operative in a pressure transducer that measures an applied pressure having a high static pressure and a high frequency low dynamic pressure, comprising: a tube member having a length L and a resonant frequency given by f=c/(4L), where c is the speed of sound, wherein said tube member receives both high static pressure and low dynamic pressure of said applied pressure at its inlet end, and wherein said tube member attenuates said high frequency low dynamic pressure, which said high frequency is higher than said resonant frequency of said tube member, and provides at an outlet end only high static pressure of said applied pressure. 20. The apparatus according to claim 19, wherein said tube member comprises a coiled tube.