Stud sensor with dual sensitivity

• US 6,023,159 A
• Filed: 07/22/1996
• Issued: 02/08/2000
• Est. Priority Date: 08/14/1992
• Status: Expired due to Term

• Current Assignee: Zircon Corporation
• Original Assignee: Zircon Corporation
• Inventors: Heger, Charles E.
• Primary Examiner(s): Snow, Walter E.
• Application Number:
  US08/684,787
• Time in Patent Office: 1,296 Days
• Field of Search: 324/225, 324/228-243, 324/67, 324/326-329, 324/658, 324/662, 324/663, 324/677, 324/686
• US Class Current: 324/67
• CPC Class Codes: G01B 7/003 for measuring position, not involving coordinate determination coordinate measuring G01B7/004
• CPC Class Codes: G01V 13/00 Manufacturing, calibrating, cleaning, or repairing instruments or devices covered by groups G01V1/00 – G01V11/00
• CPC Class Codes: G01V 3/088 operating with electric fields G01V3/082 takes precedence
• CPC Class Codes: G01V 3/15 specially adapted for use during transport, e.g. by a person, vehicle or boat

Abstract

A dual sensitivity stud sensor senses studs through both thick and thin surfaces. Studs are sensed by detecting a change in the capacitive loading of plates as they are moved along a surface and into proximity with a stud. The sensor informs the operator when the sensor has (incorrectly) been calibrated over a stud. The sensor also informs the operator if the sensor is placed against a surface either too thick or too thin for stud detection. Through use of a digital register, the sensor remains calibrated indefinitely while the sensor is powered on.

Claims

1. A dual sensitivity method for determining a location of a stud positioned behind a surface, using a sensor that senses capacitive loading by the stud, comprising:

moving the sensor over the surface, thus sensing a capacitive loading by the stud;

providing a sensitivity mode control signal to the sensor indicating one of a high sensitivity mode and a low sensitivity mode;

selecting a first digital signal representative of the sensed capacitive loading by the stud in response to selection of the high sensitivity mode;

selecting a second digital signal representative of the sensed capacitive loading by the stud in response to selection of the low sensitivity mode, the second digital signal being identical to the first digital signal but shifted by one digital bit;

adding the selected first or second digital signal to an averaged sensed capacitive loading data signal from the sensor;

converting the added signals to an analog signal; and

feeding back the analog signal to the sensor.

2. A dual sensitivity capacitive method for determining a location of a stud positioned behind a surface, comprising:

providing only a high sensitivity mode and a normal sensitivity mode, the high sensitivity mode corresponding to the stud being behind a thicker surface and the normal sensitivity mode corresponding to the stud being behind a thinner surface;

selecting the high or low sensitivity mode;

sensing a capacitive loading of the stud in the selected mode; and

indicating when the stud has been sensed.

3. A dual sensitivity capacitive stud sensor, comprising:

a capacitive loading sensor;

a sensitivity control operatively connected to the sensor for operating the sensor in a selected one of only two sensitivity modes, the modes being a high sensitivity mode and a normal sensitivity mode; and

an indicator for indicating when a stud has been sensed in either sensitivity mode.