Minelab Coil Patent Application

[GotAU?]

1 hour ago, phrunt said:

A coil that maintains normal performance while employing better EMI mitigation techniques would be a giant leap forward.

Now we're moving into a multi frequency world with our detectors EMI is increasingly becoming more of a problem.  It might not be physical shielding that solves the problem, it might be solved electronically.

An embedded processor could analyze signals and filter out EMI that has a pattern to it, that type of digital signal processing DSP is currently used for radio communications and sound analysis. When I worked as a wildlife biologist,  I used to use a bat detecting system that would analyze bat calls and it could filter out other signals and noise using DSP algorithms to enable it to identify various bat species by their calls.

[jasong]

So far their gold detectors have been the only machines that utilized patented/protected coils, haven't they? 

I don't see a lot of reason to patent a VLF only coil. I do see a reason to patent the type of coil required for a machine I've been saying is technically possible to build for a decade now, with all our modern chips and signal processing capabilities: a PI/VLF hybrid machine. The idea being, you can modulate an alternating VLF-like signal right on top of each pulse, then process and analyze with Fourier analysis each of the signals separately. It'd probably need to be 2 coils in 1. If not 4 coils in 1. 

That's my "black swan" guess. It'd give you the ability to detect shallow small stuff, or ignore surface trash and detect just deep ones (aka, depth discrimination). Also technically speaking the ability to discriminate or even ID trash on a PI - at least to VLF normal depths, which honestly is probably all prospectors need since 75% of trash is usually shallow.

I can dream anyways. 

[hosey]

Hope build quality improves !!!!!!!  

[Guest]

I'm pretty sure this is for the 6000......shhhhh. time will tell.

[EL NINO77]

https://patents.google.com/patent/US20210273335A1/en?oq=US20210273335

 

Physical laws of detection ... you can't change ....but .... but we can bend them to some extent .....
... this is a really smart idea ....

[longbow62]

Viscous Remnant Magnetism. I thought the Rockwell Retro Incabulator was supposed to solve this issue? What happens if we have a pole shift after this new coil comes out?

[phrunt]

Some important information from that Patent application.  It looks like Minelab is in the business of making new coils 🙂 This is obviously a new coil for a gold detector, could it be the GPZ 8000? Why release a completely new design coil for existing detectors when you could cash in on a new model.  Pretty cool, new improved spiral windings.

However, it is discovered that some specialised coils of metal detectors, designed fit for purpose to find gold in gold fields, have windings that are not compact in cross-sectional shape, but arranged in planar spirals with each of the successive turns being usually close to one another, typically touching one another, but in rare instances, spread apart. Windings are typically housed close to the bottom of the planar coil housing, and, spiralled coil windings are known to have their long cross-sectional axis close to coplanar with the coil housing bottom housing face, and are approximately constrained to one plane.
[0020]
These so called spiral “flat-wound” coils have three advantages for detecting small shallow targets compared to a compact bundled winding:

        a) The field generated from each turn passes closer to the target as the coil is swept over the target, and hence each specific turn for the spiral coil both irradiates the target with a greater field intensity and likewise receives the decaying eddy currents in the metal target with greater sensitivity compared to each specific turn of the compact winding on average;
        b) As the coil is swept past the target, the transmit field and receiving winding sensitivity from spiral winding are laterally broader, and hence improves electronics signal-to-noise ratio; that is, the signal from the shallow target is within the effective volume of transmitted stronger field for a longer period compared to that of a compact winding, and similarly the target is within the more sensitive areas of a spiral receive winding for longer than a compact receive winding; and
        c) As the total volume integrated 3D (magnetic field magnitude)2 for a given inductance and transmit current (½∫∫∫B2dV), the same for all coils regardless of winding shape (in the absence of permeable material), more of the strong field of compact traditional mono-loop bundle resides within or close to the perimeter of the actual bundled winding than does the field of the planar spiral winding. Hence the spiral winding has the advantage of irradiating more of its field out into the interrogated environment than the compact traditional mono-loop winding bundle, thus putting the spiral winding's field to better use for target detection.

[0024]
However, it was discovered that flat-wound coils have three disadvantages, especially for detecting deeper targets compared to a compact winding:

        a) The greater integrated field energy transmitted into the soils causes so called VRM (Viscous Remnant Magnetism) “saturation”. This is manifest as a non-cancelled ground balanced spurious signal when the coil is moved within a centimeter or so of the soil surface for some, but not all, soils;
        b) The inductance of both the receive and transmit inductive winding (or alternatively a mono-loop single winding), vary more when the said winding is closer to magnetic soils that are often associated with gold fields, than a compact winding, due to the stronger winding-to-soil coupling of the flat-wound winding. This causes the (critically) damped decay rates to change and this in turn may be detected by the electronics and manifest as spurious signals; and
        c) The spiral winding are more sensitive to local surface soil VRM inhomogeneities, and this too causes spurious signals.

[0028]
In general, the advantages of spiral winding outweighs the disadvantages in soils that have relatively low VRM mineralization for detecting shallow targets, but vice versa in soils that have relatively high mineralization. This may result in relatively poor behaviour in some soils when seeking deeply buried targets, especially when used in soils that are magnetically inhomogeneous and prone to VRM saturation.
[0029]
This disclosure provides an alternative form of a winding or a winding profile within a metal detector coil that has advantages of spiral winding and reduced level of disadvantages of spiral winding.
[0030]
The new form is based on the following. If any or all of these said three disadvantages (saturation, soil VRM inhomogeneities, modulation of critical damping) cause spurious interference signals from flat-wound coils are in effect defined as “uncancelled soil noise”, then the signal from a metal target to uncancelled-soil-noise ratio in essence mostly defines the relative capability of a coil, for given size/enclosed winding area. Further, most targets at challenging detection depths are found best when the coil passes centrally above the target, whereas the target signal for a coil's front edge or rear edge passing over a target typically will give a weaker target signal. In contrast though, for a typically any cross-sectional shape planar winding (parallel to the plane of the coil housing), the front, and rear, and each of the lateral sides, each typically produce the same soil signal contributions (per unit length). Thus, the front and rear areas of the planar mono-loop winding add the same soil signal as the sides, but relatively, a mono-loop's winding lateral sides, and center, are more responsible for the target signal as the coil passes centrally above the target for the best target signal when the coil is swung “side-to-side” centrally over the target. Hence, there is advantage in keeping the lateral sides of a winding close to the bottom of a coil housing, but not the front and rear of the winding.
[0031]
In a broad form, there is provided an antenna of a handheld metal detector for detecting a target in a soil, the antenna comprising: a housing comprising a bottom plane for facing the soil; two lateral sides; a front side; and a rear side; wherein the lateral sides, the front side and rear side are with respect to a user of the handheld metal detector holding and operating the handheld metal detector to detect the target in the soil; and at least one winding within the housing, wherein a mean distance of conductors of the at least one winding near at least one of the two lateral sides of the housing is closer to the bottom plane than a mean distance of conductors of the at least one winding near at least one of the front side and rear side of the housing.
[0032]
In another broad form, there is provided a transmitter of a handheld metal detector for detecting a target in a soil, the antenna comprising: a housing comprising a bottom plane for facing the soil; two lateral sides; a front side; and a rear side; wherein the lateral sides, the front side and rear side are with respect to a user of the handheld metal detector holding and operating the handheld metal detector to detect the target; and at least one winding within the housing, wherein a mean distance of conductors of the at least one winding near at least one of the two lateral sides of the housing is closer to the bottom plane than a mean distance of conductors of the at least one winding near at least one of the front side and rear side of the housing.
[0033]
The terms “lateral sides”, “front side”, “rear side” and “bottom plane” refer to an intended typical use of the said coil for searching targets in soils, such that the “lateral sides” refer to coil housing perimeter regions more normal to the dominant intended motion of the coil housing relative to the soil, and the “front” and “rear” refer to coil housing perimeter regions more parallel to the dominant intended motion of the coil housing relative to the soil, and “bottom” refers to the part of the coil's housing that is typically meant to be operated closest to the soil surface. In simple term, the terms “lateral sides”, “front side”, “rear side” of the housing of the transmitter of a metal detector are to be understood based on the perspective of the operator when the operator is holding the hand-held metal detector in front with the arm holding the metal detector shaft extending forward away from the body.
[0034]
In the case of vehicle-mounted metal detector antenna, the intended coil housing movement is “forward” rather than side-to-side in the direction of the vehicle's travel.
[0035]
FIG. 1A shows an exemplary embodiment of the present disclosure, and in this example shows a circular external perimeter winding 1, but this may be any shape, such as rectangular, square or elliptical for example, wound onto a coil chassis or coil's bottom base former (a guide structure to form the coil). The front side 2 of the coil perimeter has a vertically orientated monolayer section of its winding occupying approximate a quarter or a bit less than a quarter of the coil's circumference (if viewed from the top, approximate a quarter or a bit less than a quarter of the coil at the front is with the winding being vertical with respect to the base). The front side 2 is perpendicular to the coil bottom plane, and likewise the rear side 3 has a vertically orientated monolayer section of its winding occupying approximate a quarter or a bit less than a quarter of the coil's circumference. Each of the lateral sides has a horizontally orientated monolayer section of its winding occupying approximate a quarter or a bit less than a quarter each of the coil's circumference, on the right-hand side 4, the horizontal winding section, and left-hand side 5 for the left, when viewed from the rear.
[0036]
Between the said horizontally orientated monolayer sections of the winding at the left and right sides 4 and 5, and vertically orientated monolayer sections of the winding at front side 2 and rear side 3 are transitions sections 6, 7, 8 and 9 that are relatively short in length. Whilst this figure shows a monolayer winding, alternatively it may consist of two layers or more, so long as the cross-sectional profile is longer along one axis compared to another, such that the longer cross-sectional profile length defines the terms “horizontal” and “vertical” in the above description. The particular ratios of winding sectional length are not constrained to “approximate a quarter or a bit less than a quarter” each, so long as the general concept of more horizontal on the sides and more vertical on the front and rear holds. For example, the front side may occupy 20%, rear side 14%, and lateral sides 33% each (a rough approximation including transitions). In another example, the front side may occupy 20%, rear 20% and lateral sides 30% each (a rough approximation including transitions). The front and rear sides may of the same proportion, and may not. The two lateral sides are often of the same proportion but this is not a necessity.
[0037]
FIG. 1B depicts the top view of the winding of 1A. It can be seen that the winding at the front side 2 and rear side 3 are perpendicular to the bottom plane, and that the winding at the two lateral sides are parallel with the bottom plane. Transitions sections 6, 7, 8 and 9 are relatively short in length.
[0038]
FIG. 2A depicts a view from a lateral side of the winding of FIG. 1A while FIG. 2B depicts a view from a front or rear side of the winding of FIG. 1A. As can be observed, at the front side and rear side of the winding, the conductive wires are arranged to form a vertical plane 11, 12. At the two lateral sides, the conductive wires are arranged horizontally to form a horizontal plane of wires 15 parallel with the bottom plane 10. There are transitions between the vertically arranged wires and the horizontally arranged wires. In this example, vertical plane of wires 13 or 14 transit 17 or 16 to horizontal plane of wires 15.
[0039]
Further, the winding do not have to be exactly horizontal on the sides or exactly vertical at the front or rear, so long as they are closer to horizontal than vertical on the sides, and closer to vertical than horizontal at the front and rear. For example, the winding may be similar in shape to a cycling velodrome. The cross-sectional plane of the winding may be curved (such as in the case of a velodrome) or may be straight (such as in the case shown in FIG. 1A).
[0040]
In another form, a plane of the winding at the front side is extending upward away from the center at an angle between 75 to 90 degrees with respect to a horizontal plane.

 

US20210273335A1.pdf

[Cal_Cobra]

On 2/23/2022 at 10:33 AM, phrunt said:

We do know new models of VLF are coming from their annual report, I don't think any new gold machines are coming, there was no hint of it.

If they've improved VLF coils enough to need a patent it can only be a good thing, as long as it's not for "an improved wireless coil"  Then I'd cry 🙂

Perhaps it's a patent on bullet proof coil ears 😁

[Cal_Cobra]

On 2/23/2022 at 2:03 PM, GotAU? said:

An embedded processor could analyze signals and filter out EMI that has a pattern to it, that type of digital signal processing DSP is currently used for radio communications and sound analysis. When I worked as a wildlife biologist,  I used to use a bat detecting system that would analyze bat calls and it could filter out other signals and noise using DSP algorithms to enable it to identify various bat species by their calls.

That's what Fisher did on the F75 and T2 when they added their DST feature (Digital Shielding Technology).

[VicR]

US Patent Application US2021/027335 filed 26th Feb 2021 mentioned in the last few posts references Australian Patent Application 2020900585 which was filed  on 28/2/20. A full year before the US Patent Application but this Australian Application (and subsequent Aus Application 2020904645) both for a "a magnetic field transmitter of a metal detector" have lapsed in Australia.

My original post refers to Australian Patent 2022900362 filed 18th Feb 2022 which is for "a metal detector coil". This latest Patent Application may be an amendment to the two now lapsed applications or it could be something completely different.

From all this patent activity i am guessing that Minelab is banking on coil innovations as their next big thing. No new product name applications in the pipeline so could be some time away before we know anything concrete.