Simple, sensitive, frequency-tuned drop detector
First Claim
1. A detector for detecting a drop of ink of the type typically present in an ink jet printer, the detector comprising:
- a. a cover plate, defining through itself a first slot having a first long dimension;
b. a substrate, defining through itself a second slot having a second long dimension disposed to be aligned generally parallel with the first long dimension;
c. a membrane;
i. fabricated from a piezoelectric material which generates an electric signal in response to being impacted by a drop;
ii. frequency tunable to a range of selected resonant frequencies;
iii. secured at least at two locations between the cover plate and the substrate;
iv. formed with a floating region;
(1) having a generally rectangular area defined by;
(a) a pair of short ends, opposite one another, defining the shorter width dimensions of the floating region, and(b) a pair of membrane lengths, opposite one another, defining the longer length dimensions of the floating region;
(2) suspended across and between the slots with the pair of short ends being unsecured and therefore free to move;
(3) aligned with the membrane lengths generally parallel with the long dimensions of the slots;
(4) positioned to be impacted by and thereby detect the drop; and
d. a conductor means, electrically coupled to the membrane, for transmitting to an external environment the electric signal generated by the membrane.
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Accused Products
Abstract
A drop detector having a piezoelectric membrane mounted to a substrate is presented. When a drop strikes the piezoelectric membrane, the membrane vibrates at a selected resonant frequency. The resonant frequency is selected to enhance the sensitivity of the drop detector and the signal-to-noise ratio of the output. The value of the selected resonant frequency depends on the type of material used for the piezoelectric membrane, the thickness of the membrane, the mounting of the membrane to the substrate, and other parameters such as the coating on the membrane. The vibrations of the membrane produce an output signal having a frequency equal to the selected resonant frequency. Since the frequency of the output signal is known, the output signal can be filtered with a bandpass filter to enhance the signal-to-noise ratio of the output signal. The resulting membrane drop detector is a high sensitivity, high signal-to-noise ratio drop detector.
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Citations
12 Claims
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1. A detector for detecting a drop of ink of the type typically present in an ink jet printer, the detector comprising:
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a. a cover plate, defining through itself a first slot having a first long dimension; b. a substrate, defining through itself a second slot having a second long dimension disposed to be aligned generally parallel with the first long dimension; c. a membrane; i. fabricated from a piezoelectric material which generates an electric signal in response to being impacted by a drop; ii. frequency tunable to a range of selected resonant frequencies; iii. secured at least at two locations between the cover plate and the substrate; iv. formed with a floating region; (1) having a generally rectangular area defined by; (a) a pair of short ends, opposite one another, defining the shorter width dimensions of the floating region, and (b) a pair of membrane lengths, opposite one another, defining the longer length dimensions of the floating region; (2) suspended across and between the slots with the pair of short ends being unsecured and therefore free to move; (3) aligned with the membrane lengths generally parallel with the long dimensions of the slots; (4) positioned to be impacted by and thereby detect the drop; and d. a conductor means, electrically coupled to the membrane, for transmitting to an external environment the electric signal generated by the membrane. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A drop detector, comprising:
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a. a cover plate, defining through itself an oblong first slot; b. a substrate, defining through itself an oblong second slot sized to be smaller than the oblong first slot; c. a membrane; i. fabricated from a piezoelectric material which generates an electric signal in response to being impacted by a drop; ii. frequency tunable to a range of selected resonant frequencies; iii. secured at least at two locations between the cover plate and the substrate; iv. formed with a floating region; (1) having a generally rectangular area defined by; (a) a pair of short ends, opposite one another, defining the shorter width dimensions of the floating region; and (b) a pair of membrane lengths, opposite one another, defining the longer length dimensions of the floating region; (2) suspended across and between the slots with the pair of short ends being unsecured and therefore free to move; (3) aligned with the membrane lengths generally parallel with the long dimensions of the slots; (4) positioned to be impacted by and thereby detect the drop; d. a conductor means; i. electrically coupled to the membrane; ii. formed for transmitting to an external environment the electric signal generated by the membrane; e. a wiper; i. movably disposed in the vicinity of the floating region of the membrane; ii. formed for periodically being moved across the surface of the membrane to push the accumulated drops if any toward and through the first port and the second port; and f. an electromagnetic shield; i. coupled to the detector; ii. operable to attenuate an electromagnetic field if any that might otherwise degrade the performance of the membrane when detecting the drops.
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Specification