WO2021224621A1 - Détecteur de champ magnétique - Google Patents

Détecteur de champ magnétique Download PDF

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Publication number
WO2021224621A1
WO2021224621A1 PCT/GB2021/051090 GB2021051090W WO2021224621A1 WO 2021224621 A1 WO2021224621 A1 WO 2021224621A1 GB 2021051090 W GB2021051090 W GB 2021051090W WO 2021224621 A1 WO2021224621 A1 WO 2021224621A1
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WO
WIPO (PCT)
Prior art keywords
magnetic field
magnetic
antenna
detector
warning device
Prior art date
Application number
PCT/GB2021/051090
Other languages
English (en)
Inventor
Hugh-Peter Granville Kelly
Original Assignee
Direct Thrust Designs Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Direct Thrust Designs Limited filed Critical Direct Thrust Designs Limited
Priority to CN202180047155.9A priority Critical patent/CN115812158A/zh
Publication of WO2021224621A1 publication Critical patent/WO2021224621A1/fr

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Classifications

    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B21/00—Alarms responsive to a single specified undesired or abnormal condition and not otherwise provided for
    • G08B21/18—Status alarms
    • G08B21/22—Status alarms responsive to presence or absence of persons
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/05—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves 
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/103—Detecting, measuring or recording devices for testing the shape, pattern, colour, size or movement of the body or parts thereof, for diagnostic purposes
    • A61B5/11—Measuring movement of the entire body or parts thereof, e.g. head or hand tremor, mobility of a limb
    • A61B5/1113—Local tracking of patients, e.g. in a hospital or private home
    • A61B5/1114—Tracking parts of the body
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/68—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
    • A61B5/6801—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be attached to or worn on the body surface
    • A61B5/6802—Sensor mounted on worn items
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/0011—Arrangements or instruments for measuring magnetic variables comprising means, e.g. flux concentrators, flux guides, for guiding or concentrating the magnetic flux, e.g. to the magnetic sensor
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
    • G01R33/06—Measuring direction or magnitude of magnetic fields or magnetic flux using galvano-magnetic devices
    • G01R33/07—Hall effect devices
    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B21/00—Alarms responsive to a single specified undesired or abnormal condition and not otherwise provided for
    • G08B21/18—Status alarms
    • G08B21/24—Reminder alarms, e.g. anti-loss alarms
    • G08B21/245—Reminder of hygiene compliance policies, e.g. of washing hands

Definitions

  • the following invention relates to improvements in the detection of weak magnetic fields and the application of such improvements to a form of personal alarm.
  • the following invention relates to means for reducing the likelihood of a person catching a virus infection.
  • a device commonly in use for detecting magnetic fields is that known as a Hall Effect detector. This is usually in the form of a compact electronics component, typically measuring a few millimetres square by one millimetre thick. They are used in abundance throughout industry, a typical application being the detection of the steel teeth of a rotating cog passing thereby, and thus determination by circuitry of the rate of rotation of the cog.
  • a further current application is their incorporation within mobile phones, both serving as an electronic compass and a means of measuring local magnetic field strengths.
  • a Hall Effect sensor typically comprises a planar layer of doped (usually p-type) semiconductor with a detection area across which a constant current is made to flow.
  • the Hall voltage is measured across the detection area in a direction perpendicular to the direction of current flow.
  • the magnetic flux lines exert a force on the semiconductor material which deflects the charge carriers, electrons and holes, to either side of the detection area (i.e. in the direction perpendicular to the flow of current in the plane of the semiconductor).
  • This movement of charge carriers is a result of the magnetic force they experience passing through the semiconductor material.
  • a potential difference (the Hall voltage) is produced between the two sides of the semiconductor material by the build-up of these charge carriers.
  • the magnitude of the potential difference is indicative of the strength of the magnetic field
  • the detection element area of such devices meaning the magnetic field detection area- is typically tiny, for example being a circular area of just one millimetre in diameter at the centre of the component.
  • the spread of their magnetic "field of view" away from this area, which is typically conical, is limited.
  • Hall detectors are in consequence unable to register magnetic fields significantly out of line from the said field of view or where magnetic fields to be detected happen to be orthogonal to the plane of the detection area.
  • the item to be detected and issuing, or disturbing, lines of magnetic force, must be presented within the said window.
  • the strength of any magnetic field diminishes exponentially with distance, thus any Hall Effect detector must be positioned relatively close to the magnetic item to be detected.
  • a method of circumventing such limitations when detecting magnetic fields at a distance or spread over larger areas is to use an array of such devices, spread apart and at different viewing angles to one another, thereby in aggregate able to augment their effective joint magnetic field of view.
  • Each is connected to its own responsive electronics circuitry such that if any one or more detectors is/are activated, the item entering their overall field of view is registered.
  • the present invention provides a magnetic field detector comprising a magnetic antenna for garnering a magnetic field in the region of the antenna and an electronic magnetic field sensor arranged (e.g. at an end of the magnetic antenna or adjacent thereto) to detect the magnetic field garnered by the magnetic antenna.
  • the magnetic antenna of the magnetic field detector is comprised of a material with a remanence of less than 2 Gauss and/or a magnetic permeability of 8000 H/m or higher.
  • Means for augmenting the field of view of a single or more Hall Effect detectors comprises the placing of the detector(s) at or adjacent to one or more portions (e.g. an end) of magnetic antenna(e) such that the detector(s) may respond to any magnetic field alighting upon the antenna(e), the antenna(e) preferably being shaped in such manner as to be capable of garnering in encroaching and surrounding magnetic fields which otherwise would not be detectable by lone Hall Effects themselves, the antenna(e) being formed from a magnetic material having in effect zero or very substantially zero remanence such that upon departure of the magnetic fields from the vicinity of the antenna(e), no magnetic fields remain therein which would otherwise keep the Hall Effect detector(s) in an activated or substantially activated condition.
  • any antenna can be many times (hundreds, even thousands) that of the 1mm detection area of a lone Hall Effect detector, and that it thus provides significant advantages for detecting magnetic fields.
  • a suitable material which can be used to fulfil this property is that known as MuMetal. Comprising a nickel-iron soft ferromagnetic alloy and having a very high permeability, this has been widely used within magnetically sensitive equipment to shield such equipment from stray magnetic fields. A highly advantageous additional property of this material is that its remanence is effectively zero or close to zero. Thus, in accordance with an aspect of the invention, namely the non-retention within any antenna of any residual magnetic field after removal of that field, this can be realised by the use of Mumetal -or an equivalent material- for the aforesaid antenna (e).
  • the magnetic field detector further comprises a second magnetic antenna for garnering a magnetic field surrounding the second magnetic antenna, an end of the second magnetic antenna being arranged at the electronic magnetic field sensor such that the electronic magnetic field sensor can detect the magnetic field garnered by the second magnetic antenna.
  • the antenna can be in the form of a split loop.
  • Each end of the loop is placed against each opposite face of the Hall Effect detector.
  • the one end of the magnetic antenna is on an opposite side of the electronic magnetic field sensor to the other end of the magnetic antenna.
  • the loop itself between its ends is preferably not in a continuous form, ie not in one long length of material having just two ends. Rather a discontinuity, preferably a full split (by which is meant a gap) is positioned at some point, ideally midway, along its length.
  • This split is provided to ensure the value of the aggregate strengths of polarities of magnetism presented against the respective faces of the Hall Effect detector is optimised. And thus to obtain the greatest signal from the detector. The full reason for this is elusive and is explained hereinafter in full detail.
  • the magnetic antenna and the second magnetic antenna together form a loop with a discontinuity at the electronic magnetic field sensor and a discontinuity at ends of the magnetic antenna and second magnetic antenna opposite the ends at the electronic magnetic field sensor.
  • An antenna ideal for garnering in surrounding magnetic fields from a permanent magnet can be in the form of an extended flat strip (i.e. an elongate flat strip). Magnetic fields alighting upon the strip turn it effectively into a bar magnet, one end becoming a South pole and the other end a North pole.
  • the strip is highly effective for this purpose, provided that the fields reaching it are generally aimed towards its surface. This can be best considered in terms of a permanent magnet passing by an edge of the strip such that the fields emanating from the surface of the permanent magnet can be garnered onto the flat surfaces of the strip. Were the magnet to pass the strip such that the lines of force presented by the permanent magnet were orthogonal and to the side of the surfaces of the strip, there is less likelihood of them being attracted onto the said surface of the strip.
  • an antenna can be in the form of an angled strip, having in effect two faces operative in differing planes for the garnering in of prevailing magnetic fields.
  • the magnetic antenna comprises two elongate flat strips in differing planes and attached to each other along elongate sides.
  • An alternative can be for the antenna to be in the form of a tube or a thin film in a spiral, in which theoretically an infinite number of planes are covered.
  • a primary operation is to help prevention of hand to face contact in the first place and thereby to avoid accidentally ingesting and becoming infected by a virus.
  • a solution to assist in the avoidance of such contact is the provision of an alarm, warning a person to avoid hand to face contact before it takes place, and thus to prevent infection by a virus.
  • an alarm warning a person to avoid hand to face contact before it takes place, and thus to prevent infection by a virus.
  • OCD obsessive compulsive disorder
  • Cognitive behavioural therapy may thereby be feasible.
  • a form of alarm that can be employed for this purpose is the use of a magnetic field detector and a permanent magnet combination.
  • the magnetic field detector preferably a Hall Effect sensor
  • the magnetic field detector is borne upon the body of a person, for example upon the chest, and the permanent magnet is worn upon the wrist or hand. As the hand is raised to contact the face, the magnetic field emanating from the permanent magnet is detected by the Hall Effect sensor and responsive electronic circuitry sounds the alarm.
  • the magnetic field detector of the invention disclosed herein is used in a device for warning a person of the proximity of that person's hands to the face of that person before contact takes place.
  • a personal alarm comprises the use of the arrangement disclosed herein in which one or more antenna(e) are placed over a suitable area of the body and are used to garner in from an approaching permanent magnet, magnetic fields onto a single or more Hall Effect detectors, itself/themselves connected to responsive electronic circuitry to provide an alarm signal.
  • the electronic magnetic field sensor responsive circuitry can be substantially detuned only to detect magnetic fields larger than those provided by the earth's magnetic field.
  • the warning device is arranged such that the warning signal is emitted if the magnetic field garnered by the magnetic antenna detected by the electronic magnetic field sensor is greater in magnitude than a threshold value.
  • the threshold value is adjustable to allow performance to be tuned to the particular circumstances.
  • Means for powering the electronics circuitry responsive to the Hall Effect output, and so providing an alarm signal may be in the form of a dry cell battery.
  • the choice of battery can affect the performance.
  • housings for many contemporary dry cells are fabricated from mild steel. This can distort any magnetic field present and interfere with the garnering action of the antenna (e).
  • lithium ion batteries are a preferred choice, preferably those housed within plastics and thus unable to interfere with any magnetic fields present.
  • an alarm signal may be in the form of an audible tone.
  • a volume control can be provided to regulate the sound level to suit local conditions. For those periods when a user does not wish the apparatus to be active, for example when imbibing a drink, a control may be provided for temporarily de-activating the alarm.
  • the magnet is comprised of two planar halves, each held together in repulsion. By this means, the magnetic field provided by this combination is caused to propagate further than a single piece magnet of the same dimensions.
  • the two planar halves may be separated by a mild steel disc.
  • a device for warning a person of the proximity of other person(s) body or body parts to the face of the said first person, the device comprises the magnetic field detector.
  • a detector for providing a warning signal may be borne upon the body of the person to be protected.
  • the warning can be in the form of an audible signal, a visual signal, a vibration, a noticeable smell, a blue tooth connection to earphones worn by the person (or other wireless transmission means) or a combination of the foregoing, or any other means capable of alerting the person to their intended action and in sufficient time to avoid any hand to face contact.
  • a proximity detector can be in the form of a detector worn or mounted upon or about the body or neck of the person to be protected, or within a hat or other fashion accessory worn by that person, such that an electronics signal provided thereby is effective to provide a warning signal.
  • the warning can be in the form of an audible signal, a visual signal, a vibration, a noticeable smell, a blue tooth connection to earphones worn by the person (or other wireless transmission means) or a combination of the foregoing, or any other means capable of alerting the person to their intended action and in sufficient time to avoid any hand to face contact.
  • a preferred means of warning comprises a simple buzzer along with a flashing Light Emitting Diode.
  • the proximity detector can be worn upon suitable locations on the persons arms, such as his/her wrists or even - given adequate microminiaturisation- the fingers.
  • power consumption should be kept to an absolute minimum. This is especially important in cases where a virus is so virulent that authorities restrict the movement of citizens from their homes, eg to shops, to purchase replacement batteries.
  • proximity detection is provided by the use of a permanent magnet as one part of the device and, as the other part, the magnetic field detector of the present invention.
  • the permanent magnet may be housed for example within a watch like container mounted upon the wrist(s) in the manner of a watch- and the electronic magnetic field detector, upon or about the body of the person to be protected, along with appropriate electronics to sound eg a buzzer.
  • the permanent magnet may be worn on or about the body, and the magnetic field detector, along with buzzer, within the watch like container.
  • the electronic magnetic field sensor comprises a Hall Effect detector.
  • the device may be mounted upon a high permeability material such as soft iron or better MuMetal effective to disperse the magnetic field.
  • a visual counter resettable by the person, eg daily, to indicate progress.
  • the sensitivity of the detection means may be adjusted, for example by a simple potentiometer, to suit the person wearing the device.
  • An on/off switch may also be provided.
  • CBT Cognitive behavioural therapy
  • Fig la shows a single electronic magnetic field sensor (e.g. a Hall Effect detector) and Fig lb, such a detector placed adjacent to a magnetic field antenna
  • a single electronic magnetic field sensor e.g. a Hall Effect detector
  • Fig lb such a detector placed adjacent to a magnetic field antenna
  • Fig 2 shows an edge on view of a single electronic magnetic field sensor (e.g. a Hall Effect detector) sandwiched between two antennae
  • a single electronic magnetic field sensor e.g. a Hall Effect detector
  • Fig 3a shows an edge on view of a double split loop antenna sandwiching an electronic magnetic field sensor (e.g. a Hall Effect detector), and the resulting magnetic field patterns.
  • Fig 3b shows the same arrangement, but with only a single split.
  • Fig 4 Shows various forms of antennae profiled to receive magnetic fields arriving in different planes
  • Fig 5 Shows an arrangement using the invention disclosed herein to detect hand movements.
  • Fig 6 Shows an arrangement of two permanent magnets in repulsion for providing an enhanced magnetic field.
  • Figs 7a and 7b illustrate the general principle of operation of the present invention
  • Fig 8 illustrates detector means and a wrist carried permanent magnet
  • Fig 9a shows improved magnetic detection means according to the invention as does fig 9b
  • Fig 10 shows a magnetic field pattern upon antennae
  • Fig 11 shows an enclosure, antennae and lanyard means
  • Fig 12 shows in detail positioning of a Hall Effect detector adjacent to antennae
  • Fig 13 shows various options for improving the facilities provided by the detector
  • Fig 14 shows magnetic strip means for emanating magnetic fields
  • Fig 15 shows circuitry used in association with the warning device.
  • a common form of electronic field strength sensor e.g. a Hall Effect detector, hereinafter for convenience referred to as a HED
  • An electronic magnetic field sensor is a sensor which generates an electronic signal when a magnetic field is sensed. Either of the flat sides, 11 and 12 of the HED are those which must face the magnetic field to be detected.
  • the central circle 13 denotes the area receptive to magnetic fields, which may be of a diameter of just one millimetre. It is clear that any object to be detected by the HED must fall within its detection area, typically close to conical in form, as shown schematically at 14.
  • An object of the present invention is to augment substantially the magnetic field of view and thus detection area covered by such a HED, in order that distant and weak magnetic fields can be detected. A method of doing so is now shown with reference to Fig lb.
  • a magnetic antenna is used to garner a magnetic field surrounding the magnetic antenna and an electronic field sensor is used to detect the magnetic field garnered by the magnetic antenna.
  • an electronic field sensor is used to detect the magnetic field garnered by the magnetic antenna.
  • One way of doing this is to place the magnetic field sensor (at least a detection area of the magnetic field sensor) adjacent to the position at which a pole is formed when the magnetic antenna is in a magnetic field.
  • the poles formed when the magnetic antenna is in a magnetic field are at opposite elongate ends.
  • positioning a detection area of the magnetic field sensor at or adjacent to the end of an elongate antenna is advantageous because this is where the maximum magnetic field will be present, thus increasing the sensitivity of the magnetic field detector.
  • An elongate antenna is also preferred because the likelihood of magnetic poles being formed in ends (ie. being reliably formed at known, predetermined positions within the antenna) is greatly increased.
  • the magnetic antenna is elongate and preferably has a dimension in the elongate direction at least four times greater than the dimension in the directions orthogonal to the elongate direction.
  • the elongate dimension is six or even eight times the maximum dimension in the other two orthogonal directions, yet further to improve the reliability of any magnetic field resulting in the formation of a pole at the end.
  • the detection area has a plane which is orthogonal to magnetic flux lines leaving the pole of the antenna, this increases the effect on the electrons in the detection area and so increases the sensitivity of the magnetic field sensor.
  • the plane of the detection area is not necessarily the same as the plane of the housing of the Hall Effect sensor (but this is assumed to be the case in the drawings).
  • the detection area has a plane which, if placed adjacent to a side of the antenna, is offset by a maximum of 45 degrees or preferably directly faces it (because magnetic flux leaves the side of the antenna), or, in a second case, if placed at the very end of the antenna, meaning its cut end, is offset by a maximum of 45 degrees or preferably a maximum of 30 degrees or more preferably directly faces the cut end such that the plane of the detection area (and the body of the detector) is orthogonal to the longitudinal length of the antenna.
  • the second case is preferred because the flux density in this position is greatest here.
  • the detection area is within one eighth of the dimension of the elongate direction of the end of the elongate antenna ( magnetic field lines are most dense proximate to the poles).
  • the magnetic field sensor should be positioned as close as mechanically possible to the very end of the antenna, for example within 10mm of the very end.
  • the detection area is positioned centrally across the width of the magnetic antenna (i.e. on a centreline (longitudinally) of the elongate magnetic antenna).
  • the Hall Effect sensor is preferably within 1.5mm or 1.0mm of the antenna.
  • the antenna 15 is a strip antenna.
  • the strip antenna 15 is placed, end on, onto a receiving surface of the HED.
  • the very end 16 of the antenna is placed such as to contact the HED, or at least to be within 1.5mm or 1mm or 1.0mm from it.
  • Magnetic fields 17 emanating from a permanent magnet 18 are shown garnered by the antenna onto its surface, so turning the antenna into an immediate bar magnet.
  • a magnetic pole is formed at each end of the strip, and by way of illustration, a North pole is shown facing the HED.
  • the antenna can be truly long, eg 10,50 or even 100s of millimetres.
  • the magnetic field of view of the HED is thereby vastly increased by the presence of the antenna, its receiving area for magnetic fields being hundreds or thousands that of a lone HED.
  • the output of the HED is connected to electronic circuitry (not shown, but an example is described with reference to Figure 15 below) for registering the presence of a magnetic field and providing a signal in the required form.
  • the strip antenna is formed from a material having effectively zero remanence (e.g. a remanence of 2 Gauss or less), so ensuring that no residual magnetic field remains therein after removal of the permanent magnet 18 (or any other source of magnetism), otherwise the HED would remain activated.
  • a material fulfilling this requirement is commercially available, known as MuMetal.
  • MuMetal available from Magnetic Shields Limited in Headcorn, Kent, UK
  • FIG. 1 An alternative arrangement, further augmenting the area over which detection can take place, is shown with reference to Fig 2.
  • two antennae, 19 and 20 sandwich a HED, shown edge on at 21.
  • Either or both can garner in magnetic fields as shown schematically at 22 and 23.
  • a split rectangular antenna loop 24 which can for example cover a substantial area to detect encroaching magnetic fields, sandwiches a HED 25.
  • a further split is present at some point along the length of the strip, ideally half way, as shown at 26. The reason for this is elusive and as follows.
  • a HED responds in terms of a swing in its voltage output to magnetic polarity fields of the same polarity on either side of it.
  • a North pole is brought up to the left hand face of the detector, its voltage output will increase from a quiescent value, and the same if a North pole is brought up to its right hand face. If North poles are brought up to both surfaces, the signal increases further. If South poles are brought up to either or both surfaces, the output voltage will decrease from the quiescent value. Either voltage variation provides a legitimate detectable signal. If however a north pole is presented to one surface, and an equal strength south pole is presented to the opposite face, substantially no signal results.
  • the ideal solution is one in which, for any magnetic field intended to be garnered in and detected by the loop antennae, regardless of its direction, a maximised signal is provided by the Hall Effect detector. This ensures detection of even the weakest fields.
  • FIG 3a A field pattern is shown induced by the magnet 27. This is shown facing the second slit 26 ends of the antennae, resulting in like polarities being induced in both sections of the antenna ends facing it. These act to turn each of the two antennae into bar magnets, so causing like polarities (shown here as South) to form at the far ends of the antennae which sandwich the HED. These like poles combine to augment the output of the HED. Depending on the precise geometry of the antenna(e) and the positioning of the magnetic field detector(s) more than on split can be utilised.
  • a less effective arrangement is shown at Fig 3b.
  • a continuous strip antenna becomes effectively a single bar magnet in the presence of an external magnetic field, and thus can result in more equal opposite polarities forming on either side of the HED, so diminishing its output.
  • a flat strip antenna as shown in Fig lb, is ideal for garnering in magnetic fields presented towards the edge of it, the maximum being reached when they are orthogonal to its flat surface.
  • an antenna arrangement should ideally be capable of responding to any direction of magnetic field presented to it. This can be realised with the arrangement shown in Fig 4, in which the antenna 28 is shown as a right angle strip. This can then garner in magnetic fields passing by it in any direction.
  • two HEDs can be used at the end of the strip, as shown at 29 and 30, to capture between them the maximum effect of fields induced upon one or both of its two surfaces. Other geometries may also benefit from more than one HED.
  • a toroidal strip may be employed, as shown at 31, but still provided with a second slit 32. Its active ends 33 and 34, sandwich as before the HED 35, but are squashed to become flat enabling them to press up against their respective surfaces of the HED, as shown by the inset at 36.
  • the round surface of the toroid magnetic fields approaching from any direction, are garnered thereupon.
  • FIG. 5 shows the use of the antennae/Hall Effect detector combination in a personal alarm.
  • a person 37 is furnished with a magnet carrying watch-like strap 38. (This can be worn upon both wrists.)
  • An enclosure 39 is supported by a lanyard 40 and generally rests against the chest of the person.
  • the enclosure houses antennae 41 and 42 of the type shown in Fig 3a.
  • the antennae sandwich a HED 43.
  • an alarm 44 responsive to the output of the HED.
  • a warning signal is provided by the circuitry. This can be in the form of an audible alarm, a vibration or another form of signal. It is possible to adjust the strength of the warning signal (eg its loudness) as well as to enable the user to pause the operation of the device for a given period to take a drink in peace.
  • the circuitry may be battery powered, a preferred form of battery being Lithium Ion as these are commercially available without any internal or external ferromagnetic material which could otherwise interfere with the action of the antennae.
  • FIG 6 this depicts an arrangement of magnets to provide an enhanced magnetic field.
  • a single piece magnet is shown at 45.
  • Opposite polarity lines of force naturally link around the sides of this magnet as shown at 46.
  • An alternative arrangement is shown at 47 and 48.
  • the magnet 50 comprises two planar halves but held in repulsion. Lines of force thereby propagate further, as shown at 49, thereby increasing the effective reach of the said lines of force.
  • a mild steel disc (not shown) can be interposed between the two planar halves.
  • Fig 7a the body of a person using the warning device of the present invention is shown at 110 and the person's arm and hand is shown at rest at 111 and 112.
  • Proximity detection means embodying an alarm 113 is shown at 114.
  • Fig 7b shows an arm and hand at a raised position 115 in front of the person's face and the alarm 113 consequently now sounding.
  • the method of operation is simply the raising of the person's hand towards his/her face thereby resulting in proximity to the proximity detection means and thereby sounding the said alarm.
  • a miniature loudspeaker is accommodated within a housing containing the device's electronic circuitry, and programming means are used to issue a vocal friendly warning such as "have you washed your hands".
  • the electronic circuitry is fitted with switch means permitting the user of the device to de-activate its circuitry for a pre stipulated period, for example ten minutes.
  • a warning LED can be used to indicate the de activated status.
  • an identifiable series of signals may be issued, indicating that the device is again set ready for detection.
  • the device includes a switch means permitting the user of the device to prevent emittance of the warning signal for a predetermined period of time.
  • the device also includes a visual indicator to indicate to the user that the emittance of the warning signal is prevented during the predetermined time.
  • FIG. 1 the general means of detecting the presence of a magnetic field borne upon one body part when adjacent to a detector worn upon another body part is shown at 210.
  • a wrist is shown at 211, and borne upon it is a permanent magnet 212.
  • a magnetic field detector and alarm system enclosure is shown at 213, which includes an electronic magnetic field sensor 214 (e.g. Hall Sensor) for detecting magnetic fields 215 emanating from the permanent magnet 212 and circuitry (not shown) responsive to its output.
  • the circuitry is used to sound a bleeper 216 for emitting an alarm signal as the magnetic field emanating from the magnet is detected.
  • the field of response from such an arrangement is however limited.
  • An indication of the area of detection of the Hall Effect detector is shown symbolically at 217. It is self evident that the magnetic fields of 215 must fall within this area 217 to be detected. If a hand to face movement is made outside this area, it would not be registered.
  • the path taken by a hand when approaching the face is highly varied, and may not necessarily pass within the field of detection of the electronic magnetic field sensor (e.g. Hall Effect sensor).
  • the receiving area of a typical Hall Effect integrated circuit is tiny, just one or two square millimeters, and even though its magnetic field detection space envelope fans out with distance, it certainly cannot cover a wide area. It is thus possible to miss the field from the wrist mounted magnet as the hand carrying it is raised towards the face.
  • One method to cope with this, as related above, is to utilize a string of such detectors across the chest. But this is both electronically complex and drains considerable power from the batteries used to power the device. Means are preferred to achieve a reliable detection magnetically.
  • the magnetic field detector detects magnetic fields over an extended area because it comprises the use of one or more magnetic antennae disposed over all or a substantial portion of the area in which magnetism is to be detected, the antennae garnering in onto themselves at least a portion of the magnetic field present, and one or more magnetic field sensors arranged in proximity to the one or more antennae for responding to the field garnered upon them.
  • the magnetic antennae and the magnetic field sensor are used in combination to detect the presence of a first human body part in proximity to a second human body part.
  • the first human body part is a hand, or both hands, and the second human body part is the face.
  • the first human body part may be a body of one or more second person(s).
  • the magnetic field sensor may be a Hall Effect integrated circuit (ic).
  • any antenna may be used for the purpose of the present invention.
  • the magnetic antenna is at least in part, ferromagnetic in order to garner in upon it any surrounding magnetic fields.
  • the presence of residual magnetism after the physical departure of a magnetic field is undesirable to the extent it may compromise the sensitivity of the electronics used to detect the output of the Hall Effect sensor.
  • the antennae are fabricated from the especial type of magnetic material -used more commonly for magnetic shielding- known as MuMetal.
  • MuMetal This exhibits virtually zero remanence as well as being having an exceptionally high magnetic permeability, and is therefore ideal at drawing in surrounding magnetism upon itself.
  • a MuMetal usually has a relative permeability in the range of 80000- 100000H/m and so a relative permeability of above 80000 H/m is desirable.
  • the mu-metal may be of the type specified in ASTM A753-08(2013) Alloy 4.
  • a practical realization of the present invention may be the use of an enclosure resting upon the upper portion of the chest which is held in place and supported by a lanyard.
  • the magnetic antennae may be in the form of one or two wings, emanating from either side of the enclosure and extending across and optionally curved to fit the chest (e.g fig. 9a) or a split loop contained within the enclosure or located around its periphery (e.g. fig. 9b).
  • Typical and effective dimensions for each wing are length at least 100mm, for example 160mm.
  • a typical width of the antenna is 15mm, preferably with overall length 300mm, and thickness 1mm.
  • the antennae may (optionally additionally) be wound as a spiral formed from thin film. Preferably enclosed within a tube.
  • Experimental evidence shows that effective detection of antennae magnetic fields by the Hall Effect sensor is best achieved by placing the sensor at one longitudinal end of the magnetic antenna, e.g. at the longitudinal end of each antenna.
  • FIG. 9 A means of realising this requirement is shown with reference to Fig 9.
  • two magnetic antennae 218 and 219 are mounted on either side of (fig. 9a) or within (fig. 9b) the enclosure 213. Their width and field of (magnetic) view vastly expands the possible area of magnetic field detection. Any field 215 emanating from the magnet 212, is garnered by and upon them. The internal ends of the antennae are brought up to the Hall Effect sensor 214 for detection of the fields that have alighted upon the antennae.
  • an alternative arrangement of antennae and lanyards is shown at 222.
  • the enclosure holding the Hall Effect sensor and other components is shown at 213.
  • the antennae rather than being housed in the enclosure, are instead shown reaching outwardly and terminate in lanyard portions 222a and 223a. Selection of either of the methods shown in Figs 9 or 11, can be dependent upon the size/age of the person wearing the apparatus.
  • An indication of the bodily area to be covered as a wrist bearing its permanent magnet is raised towards the face is shown at B.
  • the antennae are so dimensioned and positioned such as to Garner any magnetic field arising within this defined area.
  • An aspect which improves functioning of the detector is that the ends of the antennae meet centrally and face on to the flat opposite planar surfaces of the Hall Effect sensor. That is, ends of the antennae are positioned as close as possible and as centrally as possible and with surfaces as close as parallel as possible to a planar surface of a Hall element of the Hall Effect sensor. This is shown at Fig 12. Ideally the distance "d" is zero (i.e. contact), but in practice up to one millimetre is found to suffice. If for mechanical reasons the angle 0 subtended between the antennae is less than 180 ⁇ , then the ends of the antennae 224 and 225 are optimally cut such as to still meet flat on onto the Hall Effect sensor as shown.
  • the enclosure 213 is instead equipped with rechargeable batteries as shown at 226. These may be charged by conventional mains powered chargers, or over a USB connector as shown at 227.
  • a warning LED 228 may be provided for indicating battery condition, or any other means capable of alerting the user.
  • the batteries used are preferably of the Lithium ion type, being available in plastics containers, and therefore avoiding any disturbance of the magnetic fields falling upon the antennae.
  • a small loudspeaker 229 may be incorporated within the enclosure.
  • internal programming means can be used to sound a message, such as "Hands Down” or "Have you washed your hands” and so forth.
  • a timer switch facility 230 is provided. Upon pressing this button, the device is silenced for a pre-stipulated period, for example five minutes. Upon the ending of this period, a specific bleep can be emitted to signify that the device is once again live.
  • a magnetic strip may be utilised as shown in Fig 14.
  • a ferromagnetic strip 231 is used to hold magnets 232 in a line (and all having the same outwardly facing polarity).
  • a single long magnet may be used, but magnetised face to face, rather than end to end.
  • the circuitry associated with the electronic magnetic field detector is now outlined with reference to Fig 15. Assuming a supply voltage of five volts, as shown, the typical rest or quiescent voltage output from the Hall Effect detector 138, in the absence of any magnetic field, lies half way at 2.5 volts.
  • the voltage is raised or lowered, dependent on the overall polarity of the magnetic field, ie North or South, presented to it.
  • the voltage is optionally first rectified as shown at 138b and then fed into a comparative operational amplifier 139.
  • rectification has the advantage that the circuitry operates regardless of the polarity of the wrist borne magnet providing the field to be detected.
  • the wrist magnet can thus be worn underneath the wrist, which would present one polarity or above it, which would present the opposite polarity, to suit the preference of the wearer.
  • the comparison voltage at which the amplifier triggers, and thus the strength of the prevailing magnetic field indicating the distance from the permanent magnet borne by the person, is provided by the sensitivity adjusting potentiometer 139a.
  • the minimum value is preferably set safely above the level arising from detection of the earth's magnetic field.
  • the potentiometer may be of the logarithmic type, reflecting the exponential decay of magnetic fields with distance and thus providing better adjustment.
  • the gain of the amplifier is set during manufacture.
  • the output from the said operational amplifier is used to drive via an electronics switch 140 the sounding buzzer 141 and vibrator and a flashing LED 142.
  • the output can augment a counter 141a as aforementioned.
  • Means for reducing the likelihood of a person catching a virus infection comprising the provision of a warning signal indicating the proximity of that person's hands to the face of that person.
  • Means for reducing the likelihood or a person catching a virus infection comprising the provision of a warning signal indicating the proximity of a further person or persons to the face of the aforesaid first person.
  • Means according to aspect 1 and/or 2 positioned in such manner as to detect specifically the position of a person's hand(s) relative to the face of the person.
  • warning signal is in the form of an audible signal, a visual signal, a vibration, a noticeable smell, a blue tooth connection to earphones worn by the person (or other wireless transmission means) or a combination of the foregoing, or any other means capable of alerting the person to their intended action and in sufficient time to avoid any hand to face contact.
  • Means according to aspect 4 in which the detector used to indicate the proximity of a person's hands to that person's face can be the form of a detector worn or mounted upon or about the body or neck of the person to be protected, or within a hat or other fashion accessory worn by that person, or upon the person's clothing such that an electronics signal provided thereby is effective to provide a warning signal.
  • the means may comprise a plurality of the detectors, for example spread over the body or on each hand.
  • Means according to aspects 4) to 8) in which the detector for indicating proximity is in the form of a Doppler detector.
  • a warning device configured to emit a warning signal indicative of proximity of a human body part to a head of a user.
  • the warning device of aspect 1 wherein the human body part is a face or hand. 3. The warning device of aspect 1 or 2, wherein the warning device is configured to emit a warning signal indicative of proximity of the human body part to a face of the user.
  • the warning device of any of the preceding aspects adapted to be positioned so as to detect the position of the human body part relative to the face of the user.
  • warning device of any of the preceding aspects, in which the said warning signal is in the form of an audible signal, a visual signal, a vibration, a noticeable smell, a wireless transmission signal to earphones worn by the user or a combination of the foregoing, or any other means, preferably capable of alerting the person in sufficient time to avoid any body part to head contact.
  • the warning device of any of the preceding aspects comprising a detector for detecting the proximity of an object to the head of the user and assume the object is the human body part and so cause the device to emit the warning signal if the detected proximity of the object is less than a predetermined minimum.
  • warning device of any of aspect 8, wherein the detector is adapted to be worn or mounted upon or about the body or neck of the user, or within a hat or other fashion accessory worn by the user, or upon the user's clothing such that an electronics signal provided thereby is effective to provide a warning signal.
  • the detector is adapted to be worn on the user's arms, preferably on the user's wrists, hands or finger.
  • the detector comprises a Doppler detector.
  • the warning device of aspect 8, 9, 10 or 11, further comprising an infra-red sensor and the detector is configured only to assume that the object whose proximity is detected as being less than the predetermined minimum if the infra-red sensor detects an infra-red signal within a predetermined range which is indicative of the object being a human body part.
  • warning device of aspect 13 further comprising a ferromagnetic member adapted to be worn, preferably wherein the ferromagnetic member is adapted to be worn on the user's arm, preferably the user's wrist, hand or finger.
  • the detector is a detector of a wireless electromagnetic wave and the warning device further comprises a electromagnetic wave transmitter, the one of the detector and transmitter adapted to be worn proximate the user's head and the other of the detector and transmitter adapted to be worn on the user's arm.
  • warning device of aspect 16 further comprising a magnetic antenna for garnering a magnetic field surrounding the magnetic antenna.
  • the Hall Effect sensor is arranged at an end of the magnetic antenna to detect magnetic field garnered by the magnetic antenna. 19. The warning device of aspect 18, wherein the Hall Effect sensor is within 1mm of a longitudinal end of the magnetic antenna and/or wherein a longitudinal end of the magnetic antenna is positioned adjacent a planar surface of a Hall element of the Hall sensor.
  • the magnetic antenna comprises a material with a remanence of less than 2 Gauss and/or a magnetic permeability of 80000H/m or higher.
  • a means for providing a magnetic field for detection by the Hall Effect sensor the means for providing a magnetic field preferably being in the form of one or more permanent magnets
  • the means for providing a magnetic field preferably being adapted to be mounted on the body of the user.
  • the warning device of aspect 26 further comprising an elongate ferromagnetic strip along which a plurality of said permanent magnets are attached, preferably with the same outward facing polarity.
  • each permanent magnet is comprised of two planar halves, the planar halves being held together in repulsion.
  • warning device of any of the aspects claims, further comprising a counter for counting the number of warning signals emitted by the warning device, preferably wherein the counter is user resettable.
  • warning device of any of the preceding aspects, wherein the warning signal is an audible signal, preferably a human voice.
  • warning device of any of the preceding aspects, further comprising a switch means permitting the user of the device to prevent emittance of the warning signal for a predetermined period of time.
  • the warning device of aspect 32 further comprising a visual indicator to indicate to the user that the emittance of the warning signal is prevented during the predetermined time.
  • a method of reducing the chance of virus infection of a user comprising: mounting a warning device of any of the preceding aspects on the user.
  • a method of reducing the chance of virus infection of a user comprising: mounting a warning device on a user, the warning device adapted to emits a warning signal when it detects the proximity of a human body part to a head of the user.
  • the warning device is a warning device according to any of aspects 1-33.

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Abstract

Un détecteur de champ magnétique comprend une antenne magnétique pour recueillir un champ magnétique entourant l'antenne magnétique et un capteur de champ magnétique électronique disposé de manière adjacente à ou à une extrémité de l'antenne magnétique pour détecter le champ magnétique recueilli par l'antenne magnétique.
PCT/GB2021/051090 2020-03-25 2021-05-05 Détecteur de champ magnétique WO2021224621A1 (fr)

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CN202180047155.9A CN115812158A (zh) 2020-03-25 2021-05-05 磁场检测器

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GBGB2004314.7A GB202004314D0 (en) 2020-03-25 2020-03-25 Means for reducing virus self infection
GB2006662.7 2020-05-05
GB2006662.7A GB2593550A (en) 2020-03-25 2020-05-05 Means for reducing virus self infection

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AU2021106501A4 (en) * 2020-10-23 2021-11-04 Elbaware Limited Device, system and method for determining face touching
US20220375326A1 (en) * 2021-05-20 2022-11-24 Brian Basham Device For Reducing Face-Touching

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US20040160326A1 (en) * 2003-02-12 2004-08-19 Mourad Zarouri Device and method for preventing upper respiratory diseases and for modifying certain OCD behaviors
US20060197670A1 (en) * 2005-02-24 2006-09-07 Joan Breibart Method and associated device for personal weight control
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WO2017099866A1 (fr) * 2015-12-10 2017-06-15 Bourns, Inc. Capteur de proximité magnétique à longue distance
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US20030234727A1 (en) * 2002-06-20 2003-12-25 David Perlman Biofeedback device for treating obsessive compulsive spectrum disorders (OCSDs)
US20040160326A1 (en) * 2003-02-12 2004-08-19 Mourad Zarouri Device and method for preventing upper respiratory diseases and for modifying certain OCD behaviors
US20060197670A1 (en) * 2005-02-24 2006-09-07 Joan Breibart Method and associated device for personal weight control
WO2009048018A1 (fr) * 2007-10-11 2009-04-16 Alps Electric Co., Ltd. Détecteur magnétique
US20120276525A1 (en) * 2009-11-18 2012-11-01 Kovarik Katherine R Method and system for preventing virus-related obesity and obesity related diseases
WO2017099866A1 (fr) * 2015-12-10 2017-06-15 Bourns, Inc. Capteur de proximité magnétique à longue distance
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CN115812158A (zh) 2023-03-17
GB202004314D0 (en) 2020-05-06
GB2593550A (en) 2021-09-29

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