Fluid level detector

Abstract

A transducer for use in a fluid detector for determining a presence of a fluid within a container, the transducer comprising a piezoelectric element that outputs an ultrasonic signal in response to an input electrical signal, characterized in that said transducer further comprises, a lens with an upper portion, a lower portion, and a focal point, the upper portion including a curved surface with convex side. The piezoelectric element is coupled to the upper portion of the lens so that, when the lens is disposed adjacent an outer surface of a wall of the container such that the lens is intermediate the piezoelectric element and the wall, the lens focuses the ultrasonic signal toward the focal point of the lens and on the inner surface of the wall.

What is claimed: 
     
         1 . A transducer for use in a fluid detector for determining a presence of a fluid within a container, the transducer comprising:
 a piezoelectric element that outputs an ultrasonic signal in response to an input electrical signal;   a lens with an upper portion including a curved surface with convex side, a lower portion with a contact face, and a focal point, the focal point being disposed on the contact face of the lower portion; and   wherein the piezoelectric element is coupled to the upper portion of the lens so that, when the contact face of the lens is disposed adjacent an outer surface of a wall of the container such that the lens is intermediate the piezoelectric element and the wall, the lens focuses the ultrasonic signal toward the focal point of the lens.   
     
     
         2 . The transducer as in  claim 1 , wherein the piezoelectric element comprises a piezoelectric film. 
     
     
         3 . The transducer as in  claim 2 , wherein the piezoelectric film comprises a polyvinylidene fluoride copolymer. 
     
     
         4 . The transducer as in  claim 1 , wherein the upper portion of the lens further comprises a domed surface, the piezoelectric element being operatively coupled to the convex side. 
     
     
         5 . The transducer as in  claim 1 , wherein the ultrasonic signal focused toward the focal point by the lens is a first ultrasonic signal, and when the transducer receives a second ultrasonic signal from the wall that results from the first ultrasonic signal and that is affected in a predetermined manner by presence or absence of fluid at the inner surface of the wall, the ultrasonic transducer generates an output electrical signal corresponding to the second ultrasonic signal. 
     
     
         6 . A fluid detector for determining a presence of a fluid within a container, the fluid detector comprising:
 a transducer, the transducer comprising:
 a piezoelectric element that outputs an ultrasonic signal in response to an input electrical signal, characterized in that said transducer further comprises, 
 a lens with an upper portion, a lower portion, and a focal point, the upper portion including a curved surface with convex side, 
 wherein the piezoelectric element is coupled to the upper portion of the lens so that, when the lens is disposed adjacent an outer surface of a wall of the container such that the lens is intermediate the piezoelectric element and the wall, the lens focuses the ultrasonic signal toward the focal point of the lens, the focal point being disposed on the inner surface of the wall. 
   
     
     
         7 . The fluid detector as in  claim 6 , further comprising:
 a housing including a central bore, a top portion and a base defining an aperture that communicates with the central bore,   wherein the lens and the piezoelectric element are disposed within the central bore, and the base is configured to be secured to the outer surface of the wall.   
     
     
         8 . The fluid detector as in  claim 7 , further comprising an adhesive layer disposed between the base of the housing and the outer surface of the wall. 
     
     
         9 . The fluid detector as in  claim 8 , wherein the adhesive layer further comprises a double-sided tape. 
     
     
         10 . The fluid detector as in  claim 6 , wherein the piezoelectric element comprises a piezoelectric film. 
     
     
         11 . The fluid detector as in  claim 10 , wherein the piezoelectric film comprises a polyvinylidene fluoride copolymer. 
     
     
         12 . The fluid detector as in  claim 6 , wherein the upper portion of the lens further comprises a domed surface, the piezoelectric element being operatively coupled to the convex side. 
     
     
         13 . The fluid detector as in  claim 6 , wherein the ultrasonic signal focused toward the focal point by the lens is a first ultrasonic signal, and when the transducer receives a second ultrasonic signal from the wall that results from the first ultrasonic signal and that is affected in a predetermined manner by presence or absence of fluid at the inner surface of the wall, the ultrasonic transducer generates an output electrical signal corresponding to the second ultrasonic signal.