Portable stud detector for detecting wood, metal, and live wires

• US 6,215,293 B1
• Filed: 08/12/1998
• Issued: 04/10/2001
• Est. Priority Date: 08/12/1998
• Status: Expired due to Term

• Current Assignee: Solar Wide Industrial Ltd. (Techtronic Industries Company Limited)
• Original Assignee: Solar Wide Industrial Ltd. (Techtronic Industries Company Limited)
• Inventors: Yim, Ronald Tak Yan
• Primary Examiner(s): Patidar, Jay
• Assistant Examiner(s): Zaveri, Subhash
• Application Number:
  US09/131,942
• Time in Patent Office: 972 Days
• Field of Search: 324/67, 324/236, 324/326, 307/592, 307/593, 307/594, 307/296.R
• US Class Current: 324/67
• CPC Class Codes: G01V 3/15 specially adapted for use during transport, e.g. by a person, vehicle or boat

Abstract

A portable device for selectively locating a wooden object, a metal object or a live AC wire positioned behind a wall surface covering when the device is moved along a wall surface is disclosed. Wood is detected by changes in effective dielectric constant, metal is detected by changes in magnetic reluctance and a live wire by detecting modulation signals at mains frequency. The device is controlled by a microcontroller to provide discriminating visual and audible signals when each of the kinds of objects are proximate the device.

Claims

1. A portable device for selectively locating a wooden object, a metal object or a live AC wire positioned behind a wall surface covering when the device is moved along the wall surface, the device comprising means for indicating the presence of wooden objects including, a first capacitor plate, a pair of second capacitor plates on opposite sides of the first capacitor plate and in substantially the same plane as the first capacitor plate, means for producing an output signal representative of a change in the effective dielectric constant between the first capacitor plate and the pair of second capacitor plates caused be the presence of the wooden object as the device is moved along the wall, means for monitoring the output signal and arranged to indicate the change;

means for indicating the presence of metal objects, including means for generating a magnetic field that in use extends into the wall, means for detecting changes in the effective reluctance due to metal objects in the vicinity of the device, and indicating means arranged to provide signals whenever the effective reluctance changes;

means for indicating the presence of said live wire in the vicinity of the device, including a passive antenna for responding to electromagnetic radiation and generating output signals, a bandpass filter for rejecting components of the generated output signals outside a predetermined range of frequencies, means for monitoring an output of the bandpass filter caused by said live wire for providing the indication of the proximity of live wire.

2. A portable device according to claim 1, in which the indicating means comprise LED'"'"'s.

3. A portable device according to claim 1, in which the indicating means comprise a loudspeaker controlled to produce discriminating different signals according to what is being detected.

4. A portable device according to claim 1, in which the device is controlled by a single microprocessor.

5. A portable device according to claim 1, in which the microcontroller is programmed to detect and to indicate the proximity of metal objects only, even when wooden objects are also adjacently present.

6. A portable device according to claim 1, in which the microcontroller is programmed to detect and to indicate the proximity of objects according to a priority in the order of live wires, metal objects and wooden objects.

7. A portable device according to claim 4, in which microprocessor is programmed to carry out calibration of the device as an initial step when the device is first switched on.