GB2462341A - Displacement detector having laminated shielding on winding PCBs - Google Patents

Displacement detector having laminated shielding on winding PCBs Download PDF

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Publication number
GB2462341A
GB2462341A GB0909382A GB0909382A GB2462341A GB 2462341 A GB2462341 A GB 2462341A GB 0909382 A GB0909382 A GB 0909382A GB 0909382 A GB0909382 A GB 0909382A GB 2462341 A GB2462341 A GB 2462341A
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United Kingdom
Prior art keywords
measurement path
lamination
planar surface
windings
attached
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GB0909382A
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GB2462341B (en
GB0909382D0 (en
Inventor
Mark Anthony Howard
Darran Kreit
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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
    • G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
    • G01D5/20—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature
    • G01D5/204—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature by influencing the mutual induction between two or more coils
    • G01D5/2073—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature by influencing the mutual induction between two or more coils by movement of a single coil with respect to two or more coils
    • G01D5/208—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature by influencing the mutual induction between two or more coils by movement of a single coil with respect to two or more coils using polyphase currents
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
    • G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
    • G01D5/20—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature
    • G01D5/204—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature by influencing the mutual induction between two or more coils
    • G01D5/2066—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature by influencing the mutual induction between two or more coils by movement of a single coil with respect to a single other coil
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
    • G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
    • G01D5/20—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature
    • G01D5/204—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature by influencing the mutual induction between two or more coils
    • G01D5/2073—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature by influencing the mutual induction between two or more coils by movement of a single coil with respect to two or more coils

Abstract

A detector for measuring the position of a first body relative to a second body along a measurement path comprising: a first body 5which further comprises a planar surface and a passive electromagnetic element 2 , such as a winding, and a second body 6 which further comprises a planar surface facing the planar surface of the first body and an arrangement of laminar windings 1 substantially parallel to the planar surface. A lamination 3,4 made of either a conductive or magnetically permeable material is arranged such that the lamination extends along the measurement path and is attached to first or second bodies such that the distance orthogonal to the measurement path between the laminar windings and the passive electromagnetic element is less than the distance orthogonal to the measurement path between the lamination and the planar surface of the body to which it is attached. In other word, the lamination is on the outer part of the winding carrying substrates and the windings are closer to each other than they are to the laminations. The lamination act to shield the windings from electromagnetic noise or interference.

Description

DISPLACEMENT DETECTOR
Field of the Invention
This invention relates to a displacement detector, operable to measure the displacement of two relatively moveable bodies.
Review of the Art known to the Applicant The authors have previously disclosed various electromagnetic detectors including PCT/GB2005/004946. Typically, these forms of electromagnetic detectors use laminar constructions of windings embodied as tracks on printed circuit boards (PCBs) whereby a first body, containing an arrangement of windings, is electromagnetically influenced by a second, passive body. The electromagnetic influence varies according to the relative position of first and second bodies. Such detectors offer an accurate and cost effective technique but the measurement can be influenced by nearby conductive or magnetically permeable components. These components tend to distort the electromagnetic field and hence distort or destroy the measurement. This problem can be solved by keep out zones around the detector but these can be invaded by loose components such as a stray fastener, wire or cable. Alternatively, the detectors can be surrounded in a housing which contains the detector's electromagnetic field but such constructions are costly and tend to negate the cost benefits of laminar constructions.
The present invention encompasses the concept of a low cost and robust detector construction which negates the influence of nearby conductive or magnetically permeable elements, reduces the detector's electromagnetic emissions and its susceptibility to electromagnetic noise.
Summary of the Invention
In its broadest aspect, the invention provides a device for measuring the position of a first body relative to a second body along a measurement path comprising: a first body which further comprises a planar surface and a passive electromagnetic element; a second body which further comprises a planar surface facing the planar surface of the first body and an arrangement of laminar windings substantially parallel to the planar surface; a lamination whose material is taken from the list conductive, magnetically permeable; arranged such that the lamination extends along the measurement path and is attached to first or second bodies such that the distance orthogonal to the measurement path between the laminar windings and the passive electromagnetic element is less than the distance orthogonal to the measurement path between the lamination and the planar surface of the body to which it is attached; whereby the electromagnetic influence of the first body on the second body varies according to the position of the first body relative to the second body along the measurement path.
Preferably, the detector comprises a second lamination which extends along the measurement path whose material is taken from the list conductive, magnetically permeable; attached to the body without the first lamination such that the distance orthogonal to the measurement path between the laminar windings and the passive electromagnetic element is less than the distance orthogonal to the measurement path between the second lamination and the planar surface of the body to which it is attached.
Preferably, the detector's second body is constructed from a printed circuit board.
Preferably, the detector's first body is consifucted from a printed circuit board.
Preferably, the first or second laminations are made from a copper surface.
Preferably, the electromagnetic element is a passive resonant circuit comprising a laminar winding and capacitor in electrical series.
Preferably, the laminar windings comprise a transmit winding and a receive winding.
Preferably, two of the laminar windings are displaced relative to each other along the measurement path.
Preferably, the detector has a further lamination whose material is taken from the list conductive, magnetically permeable; which extends along the measurement path and is attached to the planar surface of the body to which it is attached;
Brief Description of the Drawings
In the accompanying drawing; Figure 1 shows a sectional view of a rotary detector.
Figure 2a shows a plan view of a rotary antenna with interior and exterior conductive laminations surrounding its windings.
Figure 2b shows a sectional view of a rotary antenna with interior and exterior conductive laminations around its windings in which top and bottom windings are connected by plated via holes.
Description of the Preferred Embodiment
Figure 1 shows a section through an inductive rotary detector. An antenna [1] comprises a transmit winding and two receive windings embodied as tracks on a PCB. Preferably the PCB is FR4 grade with plated via holes. The transmit winding is energized with an AC signal preferably in the range 100kHz-i 0MHz 50 that it forms an electromagnetic field. An inductive target [2] is located within the field. Preferably the target [2] is a passive resonant circuit embodied as a laminar wound inductor and capacitor [7] in electrical series. The target's [2] inductor and the receive windings on the antenna [1] are arranged so that when the target rotates about its axis the mutual inductance between the transmit and receive windings varies continuously. The degree of mutual inductance between the transmit and receive windings indicates the target's [2] angle of rotation relative to the antenna [1].
The antenna [1] and target [2] PCBs are backed by further layers [6 & 5] of PCB insulating material. These layers [6 & 5] are plated on their rear faces preferably with 1 ounce copper to form laminations [3 & 4]. The laminations [3 & 4] are positioned at a distance [y] from the detector's antenna [1] and target [2] which is greater than the distance [x] between the antenna [1] and target [2] so that there is either no, negligible or minimal effect to the detector's measurement performance. Given the detector's operating frequency the laminations [3 & 4] effectively neutralize the influence from nearby conductive or magnetically permeable components on measurement performance.
The most important plated areas are the laminations [3 & 4] on the PCBs exterior surfaces away from the antenna [1] and target [2]. It is preferable that the sides of the PCB are also plated with copper to form a Faraday cage effect. Whilst the Faraday cage may be imperfect, the effect of any nearby conductive or magnetically permeable parts will be neutralized. The copper lamination need not be continuous to achieve the effect. The edges may be copper plated during the normal PCB production process. Any gaps in the plating where the webs connected the component PCB to its mother sheet during manufacture should preferably be small.
The laminations have a further benefit in reducing the detector's electromagnetic emissions.
Emissions and susceptibility can be reduced further with the use of ftirther laminations around either the passive electromagnetic element or the antenna windings as shown in Figure 2a & 2b. In this arrangement this additional laminations [9] are arranged around the inner and outer diameters of the antenna, extending along the edges of the antenna and across the bottom surface. All the laminations can be formed by traditional PCB production methods. To provide good adhesion between the top and bottom surfaces they can be bound together using plated via holes [8]. Preferably mirror arrangements are made on both target and antenna in rotary geometries. In linear geometries laminations should be avoided which cross the measurement path or interfere with the electromagnetic interaction between antenna and target.
Modifications and Further Embodiments The measurement path need not be circular. The measurement path can be various geometries linear, curvilinear, 2D etc. The measured electromagnetic effect need not be a change in mutual inductance.
Alternatively, the electromagnetic effect may be capacitive, a simple change in inductance of the antenna's [1] windings or other such electromagnetic effect.
The laminations need not be continuous. Alternatively the laminations may be a mesh or a series of stripes arranged so that their electromagnetic effect approximates to a continuous lamination.
The lamination may or may not be earthed; may or may not carry a current or have a voltage applied to it.
The plating material need not be copper. Other materials may also be used provided that they are substantially conductive or magnetically permeable.
The passive electromagnetic element in the target [2] need not be a passive resonant circuit. Other elements may also be used including a metal sheet, a metal component, a ferrite sheet, a ferrite component etc. The key property is that the passive electromagnetic element causes a disturbance to the electromagnetic field generated by the antenna's [1] winding.
The planar surfaces of the first and second bodies need not be simple continuous planes.
They may be complex planar or discontinuous surfaces.
The lamination may be used as a barrier between neighbouring sensors to avoid sensors in close proximity interfering with each other electromagnetically.

Claims (9)

  1. Claims 1. A detector for measuring the position of a first body relative to a second body along a measurement path comprising: a first body which further comprises a planar surface and a passive electromagnetic element; a second body which further comprises a planar surface facing the planar surface of the first body and an arrangement of laminar windings substantially parallel to the planar surface; a lamination whose material is taken from the list conductive, magnetically permeable; arranged such that the lamination extends along the measurement path and is attached to first or second bodies such that the distance orthogonal to the measurement path between the laminar windings and the passive electromagnetic element is less than the distance orthogonal to the measurement path between the lamination and the planar surface of the body to which it is attached; such that the electromagnetic influence of the first body on the second body varies according to the position of the first body relative to the second body along the measurement path.
  2. 2. A detector according to claim 1, comprising a second lamination which extends along the measurement path whose material is taken from the list conductive, magnetically permeable; attached to the body without the first lamination such that the distance orthogonal to the measurement path between the laminar windings and the passive electromagnetic element is less than the distance orthogonal to the measurement path between the second lamination and the planar surface of the body to which it is attached.
  3. 3. A detector according to any preceding claim, wherein the second body is constructed from a printed circuit board.
  4. 4. A detector according to any preceding claim, wherein the first body is constructed from a printed circuit board.
  5. 5. A detector according to any preceding claim, wherein the first or second laminations are made from a copper surface.
  6. 6. A detector according to any preceding claim, wherein the passive electromagnetic element is a passive resonant circuit comprising a laminar winding and capacitor in electrical series.
  7. 7. A detector according to any preceding claim, wherein the laminar windings comprise a transmit winding and a receive winding.
  8. 8. A detector according to any preceding claim, wherein two of the laminar windings are displaced relative to each other along the measurement path.
  9. 9. A detector according to any preceding claim, with a further lamination whose material is taken from the list conductive, magnetically permeable; which extends along the measurement path and is attached to the planar surface of the body to which it is attached.
GB0909382.4A 2008-08-05 2009-06-02 Displacement detector Active GB2462341B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB0814289A GB0814289D0 (en) 2008-08-05 2008-08-05 Detector

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GB0909382D0 GB0909382D0 (en) 2009-07-15
GB2462341A true GB2462341A (en) 2010-02-10
GB2462341B GB2462341B (en) 2012-12-12

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GB0814289A Ceased GB0814289D0 (en) 2008-08-05 2008-08-05 Detector
GB0909382.4A Active GB2462341B (en) 2008-08-05 2009-06-02 Displacement detector

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014053836A2 (en) 2012-10-02 2014-04-10 Kreit, Darran Inductive displacement detector

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0552001A1 (en) * 1992-01-14 1993-07-21 Techno Excel Kabushiki Kaisha A sensor
WO2004020936A2 (en) * 2002-08-27 2004-03-11 Tt Electronics Technology Limited Multiturn absolute rotary position sensor with coarse detector for axial movement and inductive fine detector for rotary movement
US20090079422A1 (en) * 2007-09-21 2009-03-26 Ksr Technologies Co. Inductive position sensor

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0552001A1 (en) * 1992-01-14 1993-07-21 Techno Excel Kabushiki Kaisha A sensor
WO2004020936A2 (en) * 2002-08-27 2004-03-11 Tt Electronics Technology Limited Multiturn absolute rotary position sensor with coarse detector for axial movement and inductive fine detector for rotary movement
US20090079422A1 (en) * 2007-09-21 2009-03-26 Ksr Technologies Co. Inductive position sensor

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014053836A2 (en) 2012-10-02 2014-04-10 Kreit, Darran Inductive displacement detector
WO2014053836A3 (en) * 2012-10-02 2014-05-30 Kreit, Darran Inductive displacement detector
GB2521319A (en) * 2012-10-02 2015-06-17 Darran Kreit Inductive displacement detector
US20150260549A1 (en) * 2012-10-02 2015-09-17 Darran Kreit Inductive displacement detector
GB2541141A (en) * 2012-10-02 2017-02-08 Anthony Howard Mark Inductive displacement detector
GB2541313A (en) * 2012-10-02 2017-02-15 Anthony Howard Mark Inductive displacement detector
GB2543692A (en) * 2012-10-02 2017-04-26 Anthony Howard Mark Inductive displacement detector
GB2543694A (en) * 2012-10-02 2017-04-26 Anthony Howard Mark Inductive Displacement detector
GB2521319B (en) * 2012-10-02 2017-08-02 Darran Kreit Inductive displacement detector
GB2543694B (en) * 2012-10-02 2017-09-13 Anthony Howard Mark Inductive Displacement detector
GB2543692B (en) * 2012-10-02 2017-09-27 Anthony Howard Mark Inductive displacement detector
GB2541313B (en) * 2012-10-02 2017-10-11 Anthony Howard Mark Inductive displacement detector
US10451443B2 (en) * 2012-10-02 2019-10-22 Zettlex (Uk) Limited Inductive displacement detector

Also Published As

Publication number Publication date
GB2462341B (en) 2012-12-12
GB0909382D0 (en) 2009-07-15
GB0814289D0 (en) 2008-09-10

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