Capacitive-type seed sensor for a planter monitor
First Claim
1. A sensor apparatus for detecting a flow of material along a given path of travel by detecting a change in the dielectric properties of a portion of said path of travel as the material passes therethrough, said apparatus comprising:
- electrode means disposed adjacent said path of travel and generally defining a capacitor having that portion of the path of travel adjacent thereto as a dielectric portion, such that the passage of material to be detected along the path of travel changes the dielectric constant thereof, thereby changing the capacitance of the capacitor defined by the electrode means; and
a sensor circuit comprising a tuned circuit having said capacitor defined by the electrode means coupled in circuit therewith;
said sensor circuit further comprising an oscillator circuit driving said tuned circuit at a predetermined frequency,, said predetermined frequency being selected removed from the resonant frequency of said tuned circuit in the absence of said material to be detected by an amount sufficient to cause a change in the voltage across the tuned circuit due to the flow of material along the path of travel to occur substantially entirely within a substantially constant slope, linear region of a pair of voltage-frequency curves characteristic of the response of the tuned circuit in the absence of said material and in the presence of said material respectively;
said sensor circuit further including an AM demodulator circuit coupled therewith for developing a sensor circuit output signal at a substantially constant signal level in the absence of material to be detected and for producing a measurable change in said signal level when the material to be detected is present.
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Accused Products
Abstract
A sensor apparatus for detecting a flow of material along a given path of travel by detecting a change in the dielectric properties of a portion of the path of travel as the material passes therethrough comprises one or more conductive, plate-like electrodes disposed adjacent the path of travel and generally defining a capacitor having the adjacent portion of the path of travel as a dielectric portion, such that the passage of material to be detected changes the dielectric constant, thereby changing the capacitance. A sensor circuit comprises a tuned circuit having the sensor electrode or electrodes being coupled in circuit therewith. The sensing circuit further comprises an oscillator circuit driving the tuned circuit at a predetermined frequency selected near the resonant frequency of the tuned circuit in the absence of material to be detected. The sensing circuit further includes an AM demodulator circuit coupled to the tuned circuit for developing a sensor circuit signal at a substantially constant level in the absence of material to be detected and a measurable change in signal level when the material to be detected is present.
63 Citations
24 Claims
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1. A sensor apparatus for detecting a flow of material along a given path of travel by detecting a change in the dielectric properties of a portion of said path of travel as the material passes therethrough, said apparatus comprising:
- electrode means disposed adjacent said path of travel and generally defining a capacitor having that portion of the path of travel adjacent thereto as a dielectric portion, such that the passage of material to be detected along the path of travel changes the dielectric constant thereof, thereby changing the capacitance of the capacitor defined by the electrode means; and
a sensor circuit comprising a tuned circuit having said capacitor defined by the electrode means coupled in circuit therewith;
said sensor circuit further comprising an oscillator circuit driving said tuned circuit at a predetermined frequency,, said predetermined frequency being selected removed from the resonant frequency of said tuned circuit in the absence of said material to be detected by an amount sufficient to cause a change in the voltage across the tuned circuit due to the flow of material along the path of travel to occur substantially entirely within a substantially constant slope, linear region of a pair of voltage-frequency curves characteristic of the response of the tuned circuit in the absence of said material and in the presence of said material respectively;
said sensor circuit further including an AM demodulator circuit coupled therewith for developing a sensor circuit output signal at a substantially constant signal level in the absence of material to be detected and for producing a measurable change in said signal level when the material to be detected is present. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
- electrode means disposed adjacent said path of travel and generally defining a capacitor having that portion of the path of travel adjacent thereto as a dielectric portion, such that the passage of material to be detected along the path of travel changes the dielectric constant thereof, thereby changing the capacitance of the capacitor defined by the electrode means; and
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17. A sensor circuit for use with a sensor apparatus for detecting a flow of material along a given path of travel by detecting a change in the dielectric properties of a portion of said path of travel as the material passes therethrough, wherein said sensor apparatus responds to the passage of material to be detected along the path of travel by changing its capacitance, said sensor circuit comprising:
- a tuned circuit, said sensor circuit further comprising an oscillator circuit driving said tuned circuit at a predetermined frequency, said predetermined frequency being selected removed from the resonant frequency of said tuned circuit in the absence of said material to be detected by an amount sufficient to cause a change in the voltage across the tuned circuit due to the flow of material along the path of travel to occur substantially entirely within a substantially constant slope, linear region of a part of voltage-frequency curves characteristic of the response of the tuned circuit in the absence of said material and in the presence of said material respectively;
said sensor circuit further including an AM demodulator circuit coupled with the tuned circuit for developing a sensor circuit output signal at a sdubstantially constant level in the absence of material to be detected and for producing a measurable change in said output signal level when the material to be detected is present. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24)
- a tuned circuit, said sensor circuit further comprising an oscillator circuit driving said tuned circuit at a predetermined frequency, said predetermined frequency being selected removed from the resonant frequency of said tuned circuit in the absence of said material to be detected by an amount sufficient to cause a change in the voltage across the tuned circuit due to the flow of material along the path of travel to occur substantially entirely within a substantially constant slope, linear region of a part of voltage-frequency curves characteristic of the response of the tuned circuit in the absence of said material and in the presence of said material respectively;
Specification