Patents
US 9989663 B1: Auto nulling of induction balance metal detector coils
- Granted
- 2018-06-05
- Filed
- 2016-09-09 application 15260348
- Type
- Utility · 17 claims
- Elsewhere
- Google Patents ↗ · USPTO patent document ↗ · USPTO Patent Center record ↗
Abstract
A metal detector has a large primary transmit coil, a small primary feedback bucking coil, a first receive coil, and a second receive coil. A variable resistance device is connected to the first and second receive coils. A voltage source is connected to the large primary transmit coil. The voltage source is oppositely connected to the small primary feedback bucking coil. A primary voltage is provided to the large primary transmit coil. A reverse primary voltage is provided to the small primary feedback bucking coil. The small primary feedback bucking coil is positioned near the first and the second receive coils. The metal detection methods and apparatus sums up the signals from the two secondary coils. One is over nulled, the other is under nulled. They are close enough to an inductive null to attenuate the stray coupled signals from the primary driving signal and detecting the object.
Source: PVGPATDIS, file of 2026-04-10 (ipg180605.xml).
Assignees
| Assignee | Type | Place | Also on furp.org | Source |
|---|---|---|---|---|
| White's Electronics, Inc. 9 patents | US company or organization | Sweet Home, OR | PVGPATDIS, file of 2026-04-10 |
Inventors
| Inventor | Place | Patents | Person page | Source |
|---|---|---|---|---|
| John L. Earle | Sweet Home, OR | 5 | PVGPATDIS, file of 2026-04-10 |
CPC categories
| Subclass | Category | First group | Source |
|---|---|---|---|
| G01V | Geophysics; gravitational measurements; detecting masses or objects; tags | G01V3/107 | PVGPATDIS, file of 2026-04-10 |
Cooperative Patent Classification, as currently assigned (one row per subclass).
Assignments and security interests
| Recorded | What | From | To | Reel/frame | Source |
|---|---|---|---|---|---|
| 2022-03-01 | Assignment Assignment of assignor's interest | WHITE'S ELECTRONICS, INC. signed 2020-10-16 | GARRETT ELECTRONICS, INC. GARLAND, TX | 59129/659 | ECORSEXC, file of 2026-09-25 |
| 2016-09-09 | Assignment Assignment of assignor's interest | EARLE, JOHN L. signed 2016-09-08 | WHITE'S ELECTRONICS, INC. SWEET HOME, OR | 39680/938 | ECORSEXC, file of 2026-09-25 |
Documents recorded with the USPTO Assignment Recordation Branch that list this patent. A security interest is a lender’s claim on the patent as collateral; a release ends it.
USPTO bulk data: PatentsView granted patents, disambiguated (PVGPATDIS) for patents, assignees, inventors, places and CPC categories; the USPTO Patent Assignment Dataset (ECORSEXC) for assignments and security interests. Patents filed in the last 20 years. No claims or full text. Links to other records are by name (and state): EXACT means the identical full name and state; FUZZY means a looser name match, with the confidence shown.