Communications: electrical – Condition responsive indicating system – Specific condition
Patent
1996-10-31
1998-09-22
Swann, Glen
Communications: electrical
Condition responsive indicating system
Specific condition
307116, 324 711, 324658, 340692, G05B 2100
Patent
active
058120572
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE DISCLOSURE
This invention relates to a device for finding concealed studs in hollow partitions and the like.
Stud finding devices utilising capacitive detectors are already known, e.g. from GB-B-2159630. The device described in that document makes use of a capacitor plate to which an oscillator output is applied. The device is moved over a partition containing studs and provides a display dependent on the effective capacitance of the capacitor plate. An automatic self calibrating arrangement is employed to allow the device to be set up over a part of the partition where there is no underlying stud.
The known device has the disadvantage that it is not easy to use it to find the centre of a concealed stud. The display indicates that the capacitance rises relatively rapidly as the capacitor plate starts to overlap the stud and remains at a maximum level over a considerable area. It is thus necessary for the user to note the limits of the maximum capacitance area and estimate its centre.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a device which makes finding of the centre of a concealed stud relatively simple.
In accordance with the invention there is provided a device for detecting the position of a stud in a partition comprising first and second substantially coplanar side-by-side capacitor plates which are electrically isolated from one another, means for applying an alternating signal to said plates through first and second impedance means respectively, so as to produce on said plates alternating voltage signals of amplitude related to the capacitance of each plate, means for producing a first electrical signal related to the sum of such alternating voltage signals, means for producing a second electrical signal related to the difference between such alternating voltage signals and display means including display enabling means operable in accordance with said first electrical signal and balance indicating means operable in accordance with said second electrical signal.
The display means may include three display devices operating when the display is enabled to indicate respectively (a) when the first capacitor plate has a significantly higher capacitance than the second, (b) when the capacitances of the two plates are substantially equal and (c) when capacitance of the second plate is significantly higher than that of the first.
The three display devices, which may be light emitting diodes, are preferably arranged to indicate the direction in which the device must be moved to achieve balance.
The device preferably has a self-calibrating arrangement arranged to establish a threshold level for the sum signal and a balance level for the difference signal during initial operation of the device.
BRIEF DESCRIPTION OF THE DRAWINGS
An example of the invention is shown in the accompanying drawings in which:
FIG. 1 is an elevation of a device in accordance with the invention;
FIG. 2 is a circuit diagram of the device;
FIG. 3 is a circuit diagram of a switch-on pulse circuit and a voltage regulator forming part of the device;
FIG. 4 is a graph showing voltage signals produced in the circuit of FIG. 2 and their variation with the position of the device relative to a detected stud;
FIG. 5 is a block diagram for a device in accordance with a second embodiment of the invention;
FIGS. 6 and 7 are two halves of a circuit diagram corresponding to the block diagram of FIG. 5;
FIG. 8 is a graph similar to that of FIG. 4, for the second embodiment of the invention; and
FIGS. 9 and 10 are block diagrams for third and fourth embodiments of the invention respectively, each also including a schematic graph of the type shown in FIG. 4.
DETAILED DESCRIPTION
Referring to FIG. 1, the device shown has a case 10 with a switch operating element 10.sup.b mounted on it at one side. In the front face of the case 10, there are mounted four light emitting diodes 11, 12, 13 and 14 in a diamond shaped layout, one of these leds 12 being green and triangularly shaped. One vertex of th
REFERENCES:
patent: 4191894 (1980-03-01), Noda et al.
Brooks Brian Edward
Hatcher Paul
Hepworth Paul Steabben
Swann Glen
Turner Intellectual Property Ltd.
LandOfFree
Device for finding concealed studs does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Device for finding concealed studs, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Device for finding concealed studs will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1626243