Passive ultrasonic sensors, methods and systems for their use
First Claim
1. A passive acoustic sensor for determining the value of a physical variable in a measurement region, the sensor comprising:
- a housing having two spaced apart substantially parallel and substantially flat acoustically reflecting surfaces, at least one of said acoustically reflecting surfaces is a surface on a movable member configured to be movable with respect to said housing such that the distance between said acoustically reflecting surfaces varies as a function of said physical variable, said acoustically reflecting surfaces are configured such that when incident acoustic waves having a range of frequencies are directed at said sensor in a direction substantially orthogonal to said acoustically reflecting surfaces, a first portion of said incident waves is reflected from one of said acoustically reflecting surfaces to form a first reflected wave and a second portion of said incident waves is reflected from the remaining acoustically reflecting surface to form a second reflected wave, said first reflected wave and said second reflected wave interfere to form a returning acoustic signal having at least one maximally attenuated frequency which is correlated with the value of said physical variable in the measurement region in which said sensor is disposed.
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Accused Products
Abstract
Passive acoustic sensors having at least two flat parallel acoustically reflecting surfaces. At least one reflecting surface is on a member which is movable such that the distance between the reflecting surfaces varies as a function of a physical variable to be determined. Preferably, the sensor is made such that the intensity of a first portion of incident acoustic waves which is reflected from one reflecting surface is equal or substantially similar to the intensity of a second portion of the incident acoustic waves which is reflected from the other reflecting surface. The first portion and the second portion interfere to form a returning acoustic signal having one or more maximally attenuated frequencies which is correlated with the value of the physical variable. The internal acoustic signal is received and processed to determine the value of the physical variable from one or more of the maximal attenuation frequencies. Methods and systems for using the passive sensors are disclosed.
44 Citations
31 Claims
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1. A passive acoustic sensor for determining the value of a physical variable in a measurement region, the sensor comprising:
a housing having two spaced apart substantially parallel and substantially flat acoustically reflecting surfaces, at least one of said acoustically reflecting surfaces is a surface on a movable member configured to be movable with respect to said housing such that the distance between said acoustically reflecting surfaces varies as a function of said physical variable, said acoustically reflecting surfaces are configured such that when incident acoustic waves having a range of frequencies are directed at said sensor in a direction substantially orthogonal to said acoustically reflecting surfaces, a first portion of said incident waves is reflected from one of said acoustically reflecting surfaces to form a first reflected wave and a second portion of said incident waves is reflected from the remaining acoustically reflecting surface to form a second reflected wave, said first reflected wave and said second reflected wave interfere to form a returning acoustic signal having at least one maximally attenuated frequency which is correlated with the value of said physical variable in the measurement region in which said sensor is disposed. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A passive acoustic sensor for determining the value of a physical variable in a measurement region, the sensor comprising:
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a housing;
first reflecting means formed in said housing or attached thereto, said first reflecting means has a first substantially flat acoustically reflecting surface for reflecting a first portion of incident acoustic waves directed perpendicular to said surface to form a first reflected wave;
second acoustically reflecting means formed in said housing or attached thereto, said second reflecting means has a second substantially flat acoustically reflecting surface substantially parallel to said first surface for reflecting a second portion of said incident acoustic waves to form a second reflected wave;
at least one of said first acoustically reflecting surface and second acoustically reflecting surface is a surface on a movable member configured to be movable with respect to said housing such that the distance between said first acoustically reflecting surface and said second acoustically reflecting surface varies as a function of said physical variable, said first and second acoustically reflecting means are configured such that said first reflected wave and said second reflected wave interfere to form a returning acoustic signal having at least one maximally attenuated frequency which is correlated with the value of said physical variable in the measurement region in which said sensor is disposed. - View Dependent Claims (13)
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14. A system for determining the value of a physical variable in a measurement region, the system comprising:
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at least one acoustic transducer configured for directing acoustic waves having a range of frequencies towards a passive acoustic sensor disposed in said measurement region;
at least one acoustic receiver configured for receiving acoustic waves reflected from said passive acoustic sensor to generate a received signal;
at least one passive acoustic sensor, said at least one sensor comprises a housing having at least two spaced apart substantially parallel and substantially flat acoustically reflecting surfaces, at least one of said acoustically reflecting surfaces is a surface on a movable member configured to be movable with respect to said housing such that the distance between said acoustically reflecting surfaces varies as a function of said physical variable; and
a controller unit operatively coupled to said at least one transducer and to said at least one receiver, for controlling the operation of said at least one transducer and of said at least one receiver, said controller is configured for acquiring data representing said received signal, processing said data to determine the value of at least one maximal attenuation frequency within said range of frequencies, and determining the value of said physical variable from the value of said at least one maximal attenuation frequency. - View Dependent Claims (15, 16)
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17. A method for determining a physical variable in a measurement region using a passive acoustic sensor, the method comprising the steps of:
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disposing in said measurement region a passive acoustic sensor, said sensor comprises a housing having at least two spaced apart substantially parallel and substantially flat acoustically reflecting surfaces, at least one of said acoustically reflecting surfaces is a surface on a movable member configured to be movable with respect to said housing such that the distance between said acoustically reflecting surfaces varies as a function of said physical variable;
directing acoustic waves having a range of frequencies at said sensor such that a first portion of said waves is reflected from one of said acoustically reflecting surfaces to form a first reflected wave and a second portion of said incident waves is reflected from the remaining acoustically reflecting surface to form a second reflected wave, wherein said first reflected wave and said second reflected wave interfere to form a returning acoustic signal;
acquiring data representing said returning acoustic signal;
processing said data to determine the value of at least one maximal attenuation frequency; and
determining the value of said physical variable from the value of said at least one maximal attenuation frequency. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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28. A method for using a passive acoustic sensor comprising a housing having at least two spaced apart substantially parallel and substantially flat acoustically reflecting surfaces, at least one of said acoustically reflecting surfaces is a surface on a movable member configured to be movable with respect to said housing such that the distance between said acoustically reflecting surfaces varies as a function of said physical variable, said sensor is disposed in a measurement region, the method comprising the steps of:
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directing acoustic waves having a range of frequencies at said passive sensor such that a first portion of said waves is reflected from one of said acoustically reflecting surfaces to form a first reflected wave and a second portion of said incident waves is reflected from the remaining acoustically reflecting surface to form a second reflected wave, wherein said first reflected wave and said second reflected wave interfere to form a returning acoustic signal;
acquiring data representing said returning acoustic signal; and
processing said data to determine the value of at least one maximal attenuation frequency within said range of frequencies. - View Dependent Claims (29, 30, 31)
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Specification