Acoustic liquid dispensing apparatus
First Claim
1. A liquid dispensing apparatus comprising:
- a container having a chamber for holding a liquid;
an orifice positioned at an end of the chamber for dispensing droplets of the liquid, the orifice being configured to retain the liquid in the container if the container is positioned with the orifice facing in a downward direction;
an acoustic transducer means at least partially positioned in the chamber for periodically propagating a focused acoustic beam toward the orifice and through at least some of the liquid while the liquid is contained in the chamber, the focused acoustic beam being capable of causing a droplet of the liquid to be ejected from the orifice when a free surface of the liquid is within the depth of field of the acoustic transducer means; and
a calibration surface positioned in the chamber for intercepting a part of the focused acoustic beam to generate a reflected acoustic wave that is used in determining the speed of sound in the liquid.
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Accused Products
Abstract
A liquid dispensing apparatus for dispensing droplets of a liquid, and methods for measuring various fluid parameters of the liquid are described. The liquid dispensing apparatus comprises a container having a chamber for holding a liquid. An orifice is positioned at an end of the chamber for dispensing droplets of the liquid, the orifice being configured to retain the liquid in the container if the container is positioned with the orifice facing in a downward direction. An acoustic transducer means is at least partially positioned in the chamber for periodically propagating a focused acoustic beam toward the orifice and through at least some of the liquid while the liquid is contained in the chamber, with the focused acoustic beam being capable of causing a droplet of the liquid to be ejected from the orifice when a free surface of the liquid is within the depth of field of the acoustic transducer means. Fluid parameters that can be measured include the sound velocity in the liquid, liquid level and liquid concentration, liquid acoustic impedance, liquid density and ultrasonic viscosity.
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Citations
28 Claims
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1. A liquid dispensing apparatus comprising:
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a container having a chamber for holding a liquid;
an orifice positioned at an end of the chamber for dispensing droplets of the liquid, the orifice being configured to retain the liquid in the container if the container is positioned with the orifice facing in a downward direction;
an acoustic transducer means at least partially positioned in the chamber for periodically propagating a focused acoustic beam toward the orifice and through at least some of the liquid while the liquid is contained in the chamber, the focused acoustic beam being capable of causing a droplet of the liquid to be ejected from the orifice when a free surface of the liquid is within the depth of field of the acoustic transducer means; and
a calibration surface positioned in the chamber for intercepting a part of the focused acoustic beam to generate a reflected acoustic wave that is used in determining the speed of sound in the liquid. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A method for acoustically measuring one or more fluid parameters comprising:
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propagating a test waveform from an acoustic transducer through a liquid contained in a container and towards a free surface of the liquid, the test waveform comprising a short burst of acoustic energy generated by a piezoelectric crystal positioned at a proximal end of the acoustic transducer that is focused by a lens positioned at a distal end of the acoustic transducer;
generating a step reflected wave by reflecting a portion of the test waveform off a calibration surface positioned between the acoustic transducer and the free surface, the calibration surface being positioned at a known distance from the lens;
determining a first period of time that corresponds to the time interval for the step reflected wave to travel from the lens to the calibration surface and back to the lens; and
calculating a sound velocity in the liquid by using twice the known distance of the calibration surface from the lens and the first period of time. - View Dependent Claims (19, 20, 21, 22, 23)
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24. A method for acoustically measuring one or more fluid parameters comprising:
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propagating a first test waveform from an acoustic transducer through a liquid contained in a container and towards a free surface of the liquid, the acoustic transducer comprising a piezoelectric crystal and a waveguide and the first test waveform comprising a first short burst of acoustic energy generated by the piezoelectric crystal positioned at a proximal end of the acoustic transducer that is focused by a lens formed in a distal end of the waveguide;
generating a first reflected wave by reflecting a portion of the first test waveform off the lens in the acoustic transducer;
detecting the first reflected wave with the piezoelectric crystal;
measuring the amplitude of the first reflected wave;
propagating a second test waveform from the acoustic transducer through the container when there is no liquid in the container, the second test waveform comprising a second short burst of acoustic energy similar to the first short burst of acoustic energy;
generating a second reflected wave by reflecting a portion of the second test waveform off the lens in the acoustic transducer;
detecting the second reflected wave with the piezoelectric crystal;
measuring the amplitude of the second reflected wave; and
using the amplitude of the first reflected wave and the amplitude of the second reflected wave to calculate the liquid acoustic impedance (Zf). - View Dependent Claims (25)
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26. A method for acoustically measuring the ultrasonic attenuation in a liquid comprising:
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propagating a test waveform from an acoustic transducer through a liquid contained in a container and towards a free surface of the liquid, the test waveform comprising a short burst of acoustic energy generated by a piezoelectric crystal positioned at a proximal end of the acoustic transducer that is focused by a lens positioned at a distal end of the acoustic transducer;
generating a first reflected wave by reflecting a portion of the test waveform off the lens in the acoustic transducer;
generating a second reflected wave by reflecting a portion of the test waveform off the free surface of the liquid;
detecting the first reflected wave and the second reflected wave with the piezoelectric crystal;
determining a lens signal amplitude (Alens) from the first reflected wave;
determining a liquid signal amplitude (Aliquid) from the second reflected wave; and
using the lens signal amplitude and the liquid signal amplitude to calculate the ultrasonic attenuation in the liquid from the equation;
a=½
L·
20 log [calculated (Aliquid/Alens)/measured (Aliquid/Alens)]. - View Dependent Claims (27)
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28. A method for determining the position of a calibration surface comprising:
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propagating a test waveform from an acoustic transducer through a calibration liquid at a calibration temperature contained in a container and towards a free surface of the liquid, the test waveform comprising a short burst of acoustic energy generated by a piezoelectric crystal positioned at a proximal end of the acoustic transducer that is focused by a lens positioned at a distal end of the acoustic transducer, the sound velocity in the calibration liquid at the calibration temperature being known;
generating a step reflected wave by reflecting a portion of the test waveform off a calibration surface positioned between the acoustic transducer and the free surface, the calibration surface being positioned at an unknown distance from the lens;
determining a first period of time that corresponds to the time interval for the step reflected wave to travel from the lens to the calibration surface and back to the lens; and
calculating the unknown distance by using the sound velocity and one half of the first period of time.
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Specification