Dust sensor apparatus
First Claim
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1. A dust sensing apparatus comprising:
- a transducer element comprised of a substrate and having a resonant frequency, said substrate having a top surface and a bottom surface, at least one sensor portion, and at least one conductive portion;
said substrate further comprising;
a top layer, a middle layer and a bottom layer, wherein said top layer and said bottom layer are further subdivided into a plurality of segments along an axis substantially orthogonal to a plane defined by said layers;
said at least one conductive portion further comprising at least one segment of said top layer and an opposed segment of said bottom layer; and
said at least one sensor portion comprising the remaining segments of said top layer and said bottom layer;
a plurality of excitation electrodes connected to said substrate, wherein said plurality of excitation electrodes comprises;
at least one source electrode connected to said sensor portion; and
at least one around electrode connected to said conductive portion;
a control circuit connected to said plurality of excitation electrodes, said control circuit producing an input signal having a frequency;
said input signal producing an electric field between said at least one sensor portion and said at least one conductive portion wherein said electric field is sufficient to produce oscillatory vibrational movement of said substrate.
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Abstract
A dust sensing apparatus uses a transducer element oscillating at a resonant frequency to detect changes in dust concentration. The transducer is fabricated from a polymer material which oscillates when a voltage is applied. The presence of dust affects the oscillation frequency. Dampening of the frequency by the dust presence changes the electrical resistance provided by the transducer. Electronic circuitry computes the level of dust by measuring and controlling the level of the AC signal required to maintain the oscillation frequency by monitoring the resistance.
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Citations
16 Claims
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1. A dust sensing apparatus comprising:
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a transducer element comprised of a substrate and having a resonant frequency, said substrate having a top surface and a bottom surface, at least one sensor portion, and at least one conductive portion;
said substrate further comprising;a top layer, a middle layer and a bottom layer, wherein said top layer and said bottom layer are further subdivided into a plurality of segments along an axis substantially orthogonal to a plane defined by said layers; said at least one conductive portion further comprising at least one segment of said top layer and an opposed segment of said bottom layer; and said at least one sensor portion comprising the remaining segments of said top layer and said bottom layer; a plurality of excitation electrodes connected to said substrate, wherein said plurality of excitation electrodes comprises; at least one source electrode connected to said sensor portion; and at least one around electrode connected to said conductive portion; a control circuit connected to said plurality of excitation electrodes, said control circuit producing an input signal having a frequency; said input signal producing an electric field between said at least one sensor portion and said at least one conductive portion wherein said electric field is sufficient to produce oscillatory vibrational movement of said substrate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A dust sensing apparatus comprising:
a transducer element comprised of a substrate and having a resonant frequency, said substrate having a top surface and a bottom surface, at least one sensor portion, and at least one conductive portion;
said substrate further comprising;a top surface and a bottom surface, said at least one conductive portion comprising an irradiated area of said top surface and said at least one conductive portion further comprising a diagonally opposed irradiated area on said bottom surface, and said sensor portion comprising the non-irradiated areas of said substrate; a plurality of excitation electrodes connected to said substrate, wherein said plurality of electrodes comprises; at least one source electrode connected to said sensor portion; and at least one ground electrode connected to said conductive portion; a control circuit connected to said plurality of excitation electrodes, said control circuit producing an input signal having a frequency; said input signal producing an electric field between said at least one sensor portion and said at least one conductive portion wherein said electric field is sufficient to produce oscillatory vibrational movement of said substrate. - View Dependent Claims (13)
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14. A dust sensing apparatus comprising:
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a transducer element comprised of a substrate and having a resonant frequency, said substrate having a top surface and a bottom surface, at least one sensor portion, and at least one conductive portion, wherein said transducer has a top surface having a perimeter defined by an outer edge and wherein said conductive portion comprises at least one trace on said top surface and said sensor portion comprises the remainder of the substrate; a plurality of excitation electrodes connected to said substrate, wherein said plurality of electrodes further comprises; at least one source electrode connected to said sensor portion; and at least one ground electrode connected to said conductive portion; a control circuit connected to said plurality of excitation electrodes, said control circuit producing an input signal having a frequency; said input signal producing an electric field between said at least one sensor portion and said at least one conductive portion wherein said electric field is sufficient to produce oscillatory vibrational movement of said substrate. - View Dependent Claims (15, 16)
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Specification