Multiple frequency grain moisture sensor for combines

• US 6,982,562 B2
• Filed: 06/06/2005
• Issued: 01/03/2006
• Est. Priority Date: 10/25/2001
• Status: Expired due to Term

• Current Assignee: Deere & Company
• Original Assignee: Deere & Company
• Inventors: Kozicki, Andrzej, Phelan, James J., Funk, Robert C., Slavens, Zachary W., Rains, Gerald E.
• Primary Examiner(s): Nguyen, Vincent Q.
• Application Number:
  US11/145,755
• Publication Number:
  US 20050225334A1
• Time in Patent Office: 211 Days
• Field of Search: 324/664, 324/667, 324/670, 324/689, 324/640, 324/643, 73/73, 738/617.3, 318/483
• US Class Current: 324/694
• CPC Class Codes: A01D 41/1208 Tanks for grain or chaff for threshing machines A01F12/60
• CPC Class Codes: A01D 41/1277 for measuring grain quality
• CPC Class Codes: G01N 27/223 for determining moisture content, e.g. humidity rain detectors on vehicle windows B60S1/0825
• CPC Class Codes: G01N 33/02 Food
• CPC Class Codes: G01N 33/10 Starch-containing substances, e.g. dough

Abstract

A grain moisture sensing system having an excitation signal source for producing an excitation signal. A sensor cell having a driven plate and a sense plate that applies to the excitation signal for captive measurement between the driven plate and the sense plate to produce a current at the sense plate. Connected to the excitation source is a first synchronous detector and connected to the sense plate is a second synchronous detector.

Claims

1. A grain moisture sensing system comprising:

an excitation signal source for producing an excitation signal;

a sensor cell having a driven plate for applying the excitation signal and a sense plate proximate to and substantially parallel with the driven plate for capacitive measurement across a spacing between the driven plate and the sense plate such that a sense current is produced at the sense plate;

the excitation signal source electrically connected to the driven plate of the sensor cell;

a first synchronous detector adapted for measuring components of the excitation signal, the synchronous detector electrically connected to the excitation source; and

a second synchronous detector adapted for measuring components of the sense current, the second synchronous detector operatively connected to the sense plate.

2. The grain moisture system of claim 1 wherein the first synchronous detector is adapted for alternatively measuring imaginary components of the excitation signal and real components of the excitation signal.

3. The grain moisture system of claim 1 wherein the second synchronous detector is adapted for alternatively measuring imaginary components of the sense current and real components of the sense current.

4. The grain moisture system of claim 1 wherein the first synchronous detector is a mixer and the second synchronous detector is a mixer.

5. The grain moisture sensor of claim 1 wherein the excitation signal source is a switch adapted for alternatively selecting one of a first frequency in-phase signal, a first frequency quadrature signal, a second frequency in-phase signal, and a second frequency quadrature signal.