MEASUREMENT OF MOISTURE CONTENT OF MATERIALS

• US 3,811,087 A
• Filed: 05/21/1973
• Issued: 05/14/1974
• Est. Priority Date: 05/21/1973
• Status: Expired due to Term

• Current Assignee: Juergen F. Schmelzer
• Original Assignee: Juergen F. Schmelzer
• Inventors: Schmelzer, Juergen F.
• Primary Examiner(s): Krawczewicz, Stanley T.
• Application Number:
  US05/361,899
• Time in Patent Office: 358 Days
• Field of Search: 324/58.5A,58A,61P,61R
• US Class Current: 324/688
• CPC Class Codes: G01N 27/223 for determining moisture content, e.g. humidity rain detectors on vehicle windows B60S1/0825

Abstract

An RF signal field is established through a partially conductive material, such as tobacco having a positive moisture content, and variations in the strength of the field, in response to change in the moisture content, are detected. The probe contacting the material is constructed with three conductive elements, the middle of which is grounded to provide measurements only of the strength of the RF field through the tobacco.

Claims

1. A measuring device for measuring the moisture content of a material comprising prObe means adapted to contact said material, said probe means including a block of electrically insulating material of low dielectric constant having a smooth, planar material-engaging surface, first, second and third elongated strips of conductive material embedded in said block in parallel spaced-apart manner, the plane of location of said first, second and third elongate elements being substantially parallel to said planar material engaging surface, said third elongate element being located between said first and second elongate elements, means establishing a highly stabilized RF signal at said first elongate conductive element and means connected to said second elongate conductive element for measuring the strength of the RF signal passing between said first and second elongate conductive elements through material in contact with said material-contacting surface in response to the moisture content of said material, and means grounding said third elongate conductive element to earth whereby said RF signal passing between said first and second elongate conductive elements follows an arcuate path through the material.

2. A method of monitoring the moisture content of tobacco which comprises continuously feeding a stream of tobacco having a finite moisture content from a source thereof through a monitoring zone, providing in said monitoring zone a probe including a block of electrically insulating material of low dielectric constant having a smooth planar surface in contact with which said tobacco flows, said probe including first, second and third elongate strips of conductive material embedded in said block in parallel spaced-apart manner, the plane of location of said first, and third elongate elements being substantially parallel to said planar surface, said third elongate element being located between said first and second elongate elements, continuously providing a highly stabilized RF signal to said first elongate element, continuously maintaining an RF signal field along a conductive path between said first and second elongate elements, continuously maintaining said third elongate element grounded to earth to short any conductive path directly between said first and second elongate elements, whereby said field is maintained through said tobacco, and continuously detecting changes in the strength of said RF signal field through said tobacco in response to changes in the moisture content of said tobacco.