(12) United States Patent
`Boys et al.
`
`USOO645921.8B2
`US 6,459,218 B2
`(10) Patent No.:
`Oct. 1, 2002
`(45) Date of Patent:
`
`(54) INDUCTIVELY POWERED LAMP UNIT
`(75) Inventors: John Talbot Boys; Andrew William
`Green, both of Auckland (NZ)
`(73) Assignee: Auckland UniServices Limited,
`Auckland (NZ)
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`
`(*) Notice:
`
`(21) Appl. No.: 09/780,517
`(22) Filed:
`Feb. 12, 2001
`Related U.S. Application Data
`(63) Continuation of application No. 08/793,303, filed as appli
`cation No. PCT/NZ95/00061 on Jul. 11, 1995.
`Foreign Application Priority Data
`(30)
`Jul. 13, 1994
`(NZ) ............................................... 264.000
`(51) Int. Cl." ................................................ H05B 37/00
`(52) U.S. Cl. ....................... 315/324; 315/349; 315/344;
`315/236; 315/250
`(58) Field of Search ................................. 315/324, 344,
`315/346, 267, 276, 349, 236, 254, 255,
`326, 250
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`3,611,021 A * 10/1971 Wallace ...................... 315/239
`3,873,884 A 3/1975 Gabriel ....................... 315/267
`4,595.864 A * 6/1986 Stiefelmeyer et al. ...... 315/246
`4,904998 A * 2/1990 Niimi ...................... 340/908.1
`4.914,539 A 4/1990 Turner et al. ................. 361/18
`5,293,308 A * 3/1994 Boys et al. ................... 363/37
`
`FOREIGN PATENT DOCUMENTS
`
`WO
`93/04527
`WO
`93/23907
`WO
`95-11544
`WO
`95/11545
`* cited by examiner
`
`3/1993
`11/1993
`4/1995
`4/1995
`
`Primary Examiner Michael B Shingleton
`(74) Attorney, Agent, or Firm Young & Thompson
`(57)
`ABSTRACT
`An inductively powered lamp unit 806 is fixed onto a
`Substrate and over a position where a primary inductive loop
`803 is spread apart (as at 807). At such sites, a horizontal (or
`at least parallel to the Surface of the Substrate) component of
`alternating magnetic flux is available. The conductors of the
`loop 802-803 can be inserted in a slit 804 cut into the
`Substrate. The spreading apart of the conductors may be
`ensured with a spreader 808. A power supply 801 may be a
`resonant Supply operating at 40 kHz. The lamp unit 806 does
`use a resonant pickup coil which can be shorted So as to
`minimize coupling, and provide Supply regulation. The lamp
`unit can be controlled by Signals transmitted over the
`primary loop. Applications include roadway markers and
`fire escape egreSS indicators, and underwater lighting.
`
`2,139,815. A 12/1938 Fodor ......................... 315/246
`2,265,475 A 12/1941 Fodor ......................... 315/255
`
`7 Claims, 5 Drawing Sheets
`
`
`
`Momentum Dynamics Corporation
`Exhibit 1015
`Page 001
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`

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`U.S. Patent
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`Oct. 1, 2002
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`Sheet 1 of 5
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`US 6,459,218 B2
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`N
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`305
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`N
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`N
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`306
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`3O8
`Fig 3
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`Momentum Dynamics Corporation
`Exhibit 1015
`Page 002
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`U.S. Patent
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`Oct. 1, 2002
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`Sheet 2 of 5
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`US 6,459,218 B2
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`Momentum Dynamics Corporation
`Exhibit 1015
`Page 003
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`U.S. Patent
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`Oct. 1, 2002
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`Sheet 3 of 5
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`US 6,459,218 B2
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`Momentum Dynamics Corporation
`Exhibit 1015
`Page 004
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`U.S. Patent
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`Oct. 1, 2002
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`Sheet 4 of 5
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`US 6,459,218 B2
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`701
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`904
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`(25asam, NC
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`7
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`7
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`Fig 9
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`Exhibit 1015
`Page 005
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`U.S. Patent
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`Oct. 1, 2002
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`Sheet 5 of 5
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`US 6,459,218 B2
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`1 OOO
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`4////
`1004, Z2%
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`time --->
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`1001
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`Momentum Dynamics Corporation
`Exhibit 1015
`Page 006
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`

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`1
`INDUCTIVELY POWERED LAMP UNIT
`
`RELATED APPLICATION
`This application is a continuation of application Ser. No.
`08/793,303, filed on Mar. 12, 1997. Application Ser. No.
`08/793,303 is the national phase of PCT International Appli
`cation No. PCT/NZ95/00061 filed on Jul. 11, 1995 under 35
`U.S.C. S. 371. The entire contents of each of the above
`identified applications are hereby incorporated by reference.
`
`TECHNICAL FIELD OF THE INVENTION
`This invention relates to the field of electrically driven
`lighting, to means for driving one or more lamps using
`inductive power transfer, and more particularly but not
`exclusively to the provision of emergency lights, indicating
`lights, and roadway Signal lighting powered from adjacent
`concealed cables.
`
`15
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`BACKGROUND
`Transmission of electrical power to articles which con
`Sume power over Significant gaps by means of inductive
`power transfer has become increasingly feasible with devel
`opments in resonant primary and resonant Secondary
`conductors, means to control and limit the resonant
`Secondaries, and Suitable energising power Supplies.
`There are a number of applications where even a fixed
`Source of light is advantageously driven by an inductively
`powered Source, rather than by Simple direct connections
`using conductive materials.
`In most of the situations below, Some of which are
`particularly adverse for conventional lighting, a particularly
`reliable lighting Source is an advantage and in most of these
`Situations the nature of inductive powering of lights will
`inherently enhance the reliability of a System over that using
`alternative power Supplies Such as direct connections, inter
`nal batteries, or Solar cells with rechartable batteries. Some
`Situations include:
`where electrical isolation is necessary, as in lights used in
`or near water Such as in Swimming pools or areas where
`people work in contact with water,
`where corrosive or conductive fluids are likely to occur,
`where Sparks may cause explosions, as in coal mines and
`in operating theatres or in certain other industrial Sites
`where flammable powders, gases, or the like are found,
`where the added robustness of buried cables assists in
`maintaining power transfer during exceptional
`circumstances,
`where a Surface on which lights are laid is prone to be
`replaced, Such as on a roadway with a tar Sealed
`Surface.
`In our U.S. pat. 5,293,328 we describe an inductive power
`transfer System having particular application to a multiplic
`ity of vehicles.
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`OBJECT
`It is an object of the present invention to provide an
`improved system for the inductive transfer of electrical
`energy to a Source of light or one which will at least provide
`the public with a useful choice.
`STATEMENT OF THE INVENTION
`In one aspect the invention provides an inductively pow
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`ered lamp unit; the lamp unit including one or more lamps
`capable of radiating light and comprising means to
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`US 6,459,218 B2
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`collect inductively transferred power from an external
`alternating primary magnetic field; Said collection
`means comprising a resonant circuit having a resonant
`period and including at least one inductance and at least
`one capacitance, wherein the at least one inductance
`has a winding adapted to be intersected by a portion of
`the alternating magnetic field and thereby collect power
`as a Secondary current, means capable of limiting the
`maximum amount of Secondary current circulating in
`the resonant circuit, means to transfer power at an
`output from the resonant circuit to the lamp or lamps,
`and means to control the power provided to the lamp or
`lamps.
`Preferably the means capable of limiting the amount of
`Secondary current circulating in the resonant circuit com
`prises a shorting Switch capable of closing a connection
`acroSS the inductance; the shorting Switch being controlled
`by a controller provided with means capable of Sensing the
`magnitude of the output So that when the output exceeds a
`first, higher, predetermined threshold the shorting Switch is
`closed for a period exceeding the resonant period of the
`circuit, or when the output falls below a Second, lower,
`predetermined threshold the Shorting Switch is opened;
`thereby limiting the Secondary current flowing in the
`resonant circuit So that any magnetic flux generated by
`the Secondary current does not have a Significant coun
`teracting effect on the primary field and So that the
`output of the resonant circuit is not able to exceed a
`predetermined maximum.
`Preferably the means capable of Sensing the magnitude of
`the output is configured So as to Sense an output current.
`Alternatively the means capable of Sensing the magnitude
`of the output is configured So as to Sense a relative or
`absolute output light intensity.
`Preferably the resonant inductance comprises one or more
`coils, each coil being wrapped around an elongated member
`composed of a ferromagnetic material having a midpoint,
`which member is orientated when the lamp unit is placed in
`position So as to lie with its midpoint Substantially adjacent
`to a primary conductor (capable when energised of radiating
`a primary field), and Substantially at right angles to the
`direction of the primary conductor.
`Preferably the lamp unit has a low profile and at least one
`window capable of transmitting light; the unit being capable
`of being attached to the Surface of a roadway; and wherein
`the lamp or lamps comprise one or more light-emitting
`diodes.
`It is also preferable that the lamp unit is packaged in a
`Strong housing having a low profile and at least one window
`capable of transmitting light; the unit being capable of being
`attached onto the Surface of a roadway, capable of with
`Standing loads applied by a road vehicle driving over it, and
`not capable of adversely affecting the integrity of the road
`vehicle nor deflecting the road vehicle from its course.
`Preferably the lamp unit also includes at least one ret
`roreflector unit for passively reflecting the light of vehicle
`beams.
`In another aspect the invention provides a lighting instal
`lation comprising one or more inductively powered lamp
`units as described above, each affixed to a Surface of a
`Substrate, each lamp unit being capable of emitting light on
`being energised by inductive transfer of power acroSS a
`Space from a primary conductor located beneath the Surface
`of the Substrate; the primary conductor carrying, when in
`use, an alternating current.
`Preferably the primary conductor radiates an external
`alternating magnetic field, at a frequency which is Substan
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`Page 007
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`US 6,459,218 B2
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`tially the same as the resonant circuit in at least one of the
`lamp units, the frequency lying in the range of between 200
`HZ and 2 MHZ.
`Preferably the primary conductor is laid down within a
`Substrate in the topology of a loop, connected at a first open
`end to a power Supply and having a Second, closed end, the
`loop comprising a pair of closely spaced conductors, though
`Spread apart in an axis Substantially perpendicular to the
`Surface of the Substrate at each site where a lamp unit is to
`be placed.
`Preferably the one or more inductively powered lamp
`units are placed upon the Substrate So as to guide a moving
`person (whether on foot or Steering a vehicle) to pass along
`a particular route.
`Preferably one or more lamp units may be selectively
`addressed using the primary conductor as a medium, So that
`the light radiated therefrom may be changed from time to
`time.
`Preferably Selective addressing is accomplished by Super
`imposing a message over the primary current, in the form of
`momentary variations of the amplitude of the primary cur
`rent.
`Preferably Selective addressing is accomplished by Super
`imposing a message over the primary current, in the form of
`momentary variations of the phase of the primary current.
`Preferably Selective addressing is accomplished by Super
`imposing a message over the primary current, in the form of
`information carried within a carrier frequency, Separate from
`the frequency of the power for inductive transfer.
`Preferably Selective addressing is accomplished by Setting
`the frequency of the primary current So as to match the
`resonant frequency of the resonant circuit of the addressed
`one or more lamp units which, for this purpose, may each be
`provided with one of a variety of resonant frequencies.
`In another aspect the invention provides an installation for
`laying out marking lights on a road, comprising a set of
`inductively powered roadway markers, a primary energising
`loop cable, and a power Supply.
`Preferably the power Supply is capable of energising the
`primary energising loop in response to an external triggering
`eVent.
`Preferably the power Supply is capable of remotely con
`trolling one or more lamp units by means of the primary
`energising loop.
`Preferably the power Supply is capable of remotely con
`trolling one or more lamp units by means of the primary
`energising loop in response to an external triggering event.
`In another aspect the invention provides an installation for
`laying out marking lights along a fire escape route or egreSS
`route in relation to a building, comprising a set of induc
`tively powered lamp units, a primary energising loop cable
`capable of being buried within a substrate of the building,
`and a power Supply having a battery backup; the installation
`being capable of being activated during an emergency.
`Preferably the primary alternating current is a Sine wave.
`Preferably it has a frequency in the range of from 500 Hz
`to 1 MHz, although more preferably it has a frequency in the
`range of from about 10 KHZ to about 50 KHZ.
`Preferably the alternating current is generated within a
`resonant power converter.
`Preferably the concealed primary cable is electrically
`insulated and mechanically protected by being embedded
`within the substrate. Optionally it may be sealed into a slit
`cut into the Substrate with a circular saw or the like.
`Preferably the concealed cable comprises a pair of con
`ductors orientated Substantially perpendicular to the Surface
`of the Substrate, although optionally a pair of conductors
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`may lie side by side within parallel slits. Preferably the cable
`is composed of a litz wire or other wire having a high
`Surface-to-volume ratio Such as a Strip.
`In another aspect the invention provides a lamp unit
`within a Strong housing, comprising a resonant Secondary or
`pickup coil and capacitor, one or more light-emitting lamps,
`and optionally power conditioning means.
`Optionally the lamp unit has a low profile and may be
`applied to a road Surface.
`Optionally the lamp unit also contains one or more
`retro-reflector modules.
`Preferably the power conditioning means comprises a
`current limit and optionally this may be built into light
`emitting diodes or be an intrinsic property of metallic
`filament lamps.
`In the case of light-emitting diodes, a pair of lamps or of
`banks of lamps may be connected in inverse parallel in order
`to utilise both half-cycles of an AC waveform.
`In a further aspect the invention may provide a road
`markings Set of lamps comprising a Series of lamp units, an
`embedded cable, and a power Supply.
`Optionally this invention may be used to highlight dan
`gerous portions of a highway.
`Optionally it may be energised by the proximity of a
`vehicle.
`In a related aspect the invention provides a pedestrian
`crossing, comprising means to detect the presence of a
`waiting pedestrian, Sets of road markings, and a Sequencer to
`energise the road markings lamps for a period of time before
`Signalling to the pedestrian that a warning has been given.
`In a yet further aspect the invention may provide a fire
`escape indication Set of lamps.
`Preferably the power supply for the invention is driven
`from a set of Storage batteries So that it can operate in the at
`least temporary absence of a mains Supply.
`DRAWINGS
`The following is a description of a preferred form of the
`invention, given by way of example only, with reference to
`the accompanying diagrams.
`FIG. 1: is an illustration of a section through a light
`housing above a pair of primary conductors embedded in a
`Substrate.
`FIG. 2: is a perspective view of a row of lights energised
`inductively by alternating current in a concealed cable.
`FIG. 3: illustrates energisation using a cable carried
`within a single vertical slit.
`FIG. 4: Shows a typical circuit for use in a light housing
`of the present invention.
`FIG. 5: shows a preferred circuit including control of the
`resonant pickup circuit.
`FIG. 6: shows a preferred circuit like FIG. 5, also includ
`ing means for detecting and responding to control impulses.
`FIG. 7: shows the interior of a roadway marker incorpo
`rating a pair of ferrite Strips as pickup devices to collect
`inductive power.
`FIG. 8: shows the disposition of the primary inductive
`loop in an installation.
`FIG. 9: shows the flux about the primary conductors,
`entering the ferrite mainly at its ends.
`FIG. 10: shows options for controlling the output of
`individual lamp units by way of currents within the primary
`conductor.
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`PREFERRED EMBODIMENTS
`One application of this invention is for “self-illuminated
`“cats-eye style” roadway reflectors. This specification
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`describes an installation for laying out a Series of marking or
`warning lights (which may also include retro-reflectors)
`along a generally linear course, and particular applications
`for these lights include roadway lighting. Here they may be
`substituted for the well-known “cats-eye' retro-reflectors
`which are placed upon the road and being of low profile,
`may be driven over. Many applications beyond the known
`range of uses for “cats-eye' reflectors become available for
`a System of Self-powered units.
`In relation to another application; fire egreSS lighting, the
`type of energisation used in this invention offerS advantages
`over conventional lighting in that the invention is more
`resistant to fire damage than other types of emergency
`guidance and therefore will persist for a longer time.
`We shall describe a basic type of light unit and cabling,
`(Example 1) and a more advanced type of light unit
`(Example 2) as reduced to practice, but it should be realised
`that these examples are in no way limiting and that further
`examples, exploiting the characteristic features of the
`invention, may become obvious to the skilled reader.
`In principle, we feed alternating current at preferably
`about 36-40 KHZ and at a sufficient current (typically
`10-12A) into a cable buried within the substrate of the road
`or building or the like, and provide radiated magnetic flux
`from the cable at discrete Sites for use in energising lamp
`units adapted for using inductive power transfer. Although it
`is convenient and effective to use resonating current and a
`resonant power Supply to power the primary inductive loop
`(the cable) power of similar characteristics could be gener
`ated in other ways.
`Principles of resonant pickup of inductive power do apply
`for effective operation of the lamp units and the Examples
`illustrate this.
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`EXAMPLE 1.
`Our most basic System comprises:
`(a) A power Supply 200, generating a Sine-wave output of
`a desired power level at usually around 40 KHZ into a
`(mainly inductive) resonating cable 201, and in the
`applications described herein here at a power level of
`perhaps up to 100-200 watts although much higher
`levels can be generated.
`(b) A cable 201 of up to 800-1000 m length having
`closed-loop topology which is placed alongside the
`intended position of a or each lamp unit 203, 204. We
`prefer to use litz wire in installations where efficiency
`and long-term reliability at high loading levels is
`important, although for cheapneSS ordinary insulated
`copper (or aluminium) cables can be used.
`(c) One or more lamp units 203, 204, 100, laid out in a
`Series like a chain, each of which units comprises a
`pickup coil preferably resonant at the power Supply
`frequency, one or more lamps, and preferably power
`conditioning means. We generally prefer light-emitting
`diodes as they are reliable.
`The cable can be laid out as a Single U-shaped loop or can
`be run out along Several branches, though preferably as a
`Single length without joins. A particular application may
`require tuning, as only one length has the correct resonant
`frequency and for this purpose the installer can either vary
`the resonating capacitors within the power Supply or add
`toroids (including air gaps) over the cable to artificially
`increase its inductance and thereby Simulate a longer cable
`than is actually present. We prefer to run the cable at a low
`power and at a low Voltage, for Safety’s Sake.
`AS there are no exposed metallic conductors in an induc
`tively powered lighting System, it may be used for long
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`periods in a corrosive atmosphere or one where Seawater is
`present. The relative absence of risk of Sparks allows its use
`in inflammable or explosive situations.
`FIG. 1 illustrates the road warning lamp 100 of Example
`3 in place on a road surface 102. In this drawing we have
`shown the energising cables 109 in a parallel pair of slits
`108, although roading engineers prefer a single Slit as 302 in
`FIG. 3. The lamp 100 comprises a tough housing 101,
`having a clear or translucent window in front of an array of
`lights or preferably light-emitting diodes 103. These diodes
`derive their power from a secondary pickup coil 104 which
`is made resonant at about the preferred operating frequency
`by a capacitor 106, and the lamps are driven through a
`rectifier module 107. The slits 108 in the roadway 102 are
`preferably filled with a matrix. FIG. 3 illustrates the vertical
`wiring alternative, in which the secondary coil 304 is placed
`above the slit 302 containing the pair of wires 305. Prefer
`ably the Slit is cut deeper at about the intended position of
`each lamp unit 306, so that one of the cables 308 may be
`brought deeper and So increase the inductive field available
`at that point. Between lamp units, the cable 305 has a
`reduced inductance where its conducting members are closer
`together and So an increased length of cable can be driven
`with a limited Voltage. A further way to enhance the mag
`netic flux at a lamp Site is to use a ferrite rod or peg as at 205
`in FIG. 2. This may limit the freedom of placement of lamp
`units. Ferrite may be incorporated within lamp units, as
`suggested by the core of the inductor 401. At least one
`conductor may, instead of being litz wire, be a flat Strip of
`metal, as this will raise the amount of Surface available for
`carrying skin-effect currents.
`FIG. 4 shows one preferred circuit, in which 401 and 402
`comprise a resonant circuit, 403 is a rectifier to make a DC
`voltage, and 405 is a set of LED lamps in series. 404 may
`be a shunt regulator acting as a current limiter, or a flasher
`module. Preferably, 404 is a repetitively acting shorting
`switch (see 503 with 501, 502 in FIG. 5). If a current limiter
`is not used, the operating current in the lamps may be set to
`the usual preferred value of around 20 mAby choosing from
`a range of lamp units or placing a lamp unit So as to give a
`predetermined brightness.
`EXAMPLE 2
`This portion of the Specification describes a preferred
`inductively powered lamp unit. There are two versions,
`shown as FIG. 5 (no ability for external control) and FIG. 6
`having internal means for detecting and responding to
`control impulses. Certain parts of these two circuits have
`been discussed in relation to FIG. 4.
`The non-controlled circuit is shown as 500 in FIG. 5. The
`resonant pickup coil 401 may actually comprise two coils
`704 (as in FIG. 7) wound around each ferrite strip 703, and
`if Several coils are used they are placed in Series. The
`capacitor(s) of the resonant circuit are shown at 402; here
`247 nF and including provision (pads) on the circuit board
`for adding a Small "tuning capacitor. The resonant fre
`quency is at about 40 KHZ. The bridge rectifier 403 is made
`up of four diodes (type BAT83), the output of which is
`passed through an inductor 501 (7.5 mH) and through a
`steering diode 502 (BAT83) to charge a capacitor 505 (33
`FF, 25V). Power FET transistor 503 (type IFRD110) is used
`as a shorting Switch to short out the resonant circuit from
`time to time, each time lasting for a number of cycles. Means
`to control the shorting Switch comprise the operational
`amplifier/comparator 506 (type MC33171) which has at its
`inverting input a Zener diode 510 (type TC9491) as a voltage
`reference. The comparator compares the Zener Voltage with
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`Page 009
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`7
`a proportion of the current passed through the output lamps
`at resistor 610 (30 ohms) (via a 1K resistor 509) and uses a
`diode 507 (type BAT83) in series with a 68K resistor 508 as
`a non-inverting feedback loop, for hysteresis. This control
`circuit provides a controlled current centered on a design
`value and fluctuating to a Small extent about that value when
`the resonant circuit is alternately shorted, then allowed to
`charge the capacitor 505. Typically, there are about 500
`Shorting events per Second.
`Providing current regulation of this type allows the lamp
`unit to emit Substantially a controlled amount of light
`regardless of its position, within limits. Exact placement is
`not critical. It is not uncommon for a marker on a hot,
`tar-sealed road to be displaced laterally by tires of heavy
`vehicles and this regulation provides Some tolerance to
`displacement after positioning.
`In our preferred circuit two chains (405) of high-intensity
`(orange) light-emitting diodes (type HLMT-CL00) are used
`to radiate light to one Side of the lamp unit. Of course, other
`colours could be used.
`Variations to FIG. 5 include (for example) monitoring the
`ambient light with a light-dependent resistor, So that the
`brightness of the marker is proportional to daylight, or
`regulating current in terms of actual light output rather than
`lamp current.
`FIG. 6 illustrates one means 600 for rendering the circuit
`capable of being externally controlled. AS Suggested in FIG.
`10, it is possible to Superimpose control signals over the
`resonant power circulating in the primary loop. This circuit
`is well-adapted for control by means of low-frequency tones
`or dual tones. FIG. 6, which is a development of FIG. 5 and
`includes the components of FIG. 5, also includes means to
`short-circuit the pickup coil 401 from time to time (typically
`once per millisecond) and during that time read the current
`circulating in the primary loop. This circuit is tentative
`because it appears that an application-Specific integrated
`circuit will be an appropriate implementation.
`Box 602 represents a clock generator producing a pulse of
`50 Fsec every 1 m.sec. (There is no requirement to synchro
`nise all clocks in all markers in an installation to pulse
`synchronously). Its output is passed to (a) an AND gate 606
`shared by the comparator and Supplying the gate of the
`power FET, 503. Its output also goes to the control input of
`a sample and hold circuit 603, which reads the current across
`a current sense resistor 601 inserted in the Source lead of
`503. At times when the Switch 503 is closed, the resistor will,
`after a cycle or two at 40 KHZ, or about 50 FSec, have a
`Voltage on it representing the current in the primary induc
`tive loop at that time. This voltage is taken to the Signal input
`of the Sample and hold circuit, and the output is passed to a
`circuit 604 which comprises a tone detector.
`In this simple example we have provided a resistor 605
`between the tone detector output and an input of the
`comparator, So that activation of the tone detector has an
`effect on the setting of the comparator 506 and the mean
`brightness of the lamps is altered as a result of detecting a
`Specific tone carried within the primary inductive loop.
`“Stealing time” from the action of the comparator as for
`FIG. 5 is of little moment because the inherent regulation
`can compensate. Repetitive Sampling at a rate of about 1
`KHZ will satisfy the Nyquist criterion for control signals
`which are single or multiple tones of up to about 250 Hz.
`Clearly there are many possible options, Such as whether
`or not the tone detector outputs Switch from one State to
`another State on each tone detection, or change State only
`during a tone, and there may be more than one tone and
`
`15
`
`25
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`US 6,459,218 B2
`
`8
`hence more than one action, or the detector output may be
`treated as a code Signal passed to a microprocessor which
`will execute one of a Series of actions on the light output
`from the lamps 405. There may be a red series and a yellow
`(or orange, green or blue or even infra-red) series of lamps
`which can be driven Separately, or Separately controllable
`lamps may face in various directions.
`HIGHWAY MARKERS
`In FIG. 7, we show a highway marker 700 from above.
`The casing 701 encloses a pair of ferrite cores 703 (only one
`core and coil is labelled) which are on each side of a
`printed-circuit board 702 bearing the circuit of FIG. 6 and
`along one edge a row of light-emitting diodes 705. We have
`not also illustrated retro-reflectors in this diagram, but they
`may be interspersed with the diodes 705.
`FIG. 8 shows part of a roadway installation in side view.
`A power Supply 801 puts power into a loop of cable forming
`a primary inductive loop. In the portions where the two
`conductors are close together (802) the flux tends to cancel
`out and the cable radiated little flux. Hence it may be
`elongated. At positions (803) where a lamp unit (804) may
`be placed, the cable is spread apart, preferably using a
`spreader (805) to maintain spacing during and after instal
`lation. The end of the loop remote from the cable is shown
`at 806.
`If the power Supply is a resonant power Supply, and this
`type of energisation is economical and, by energising the
`cable with a Sine wave, minimises problems of radiation of
`radio or electromagnetic energy, it is preferable to use litz
`wire for the cables. We prefer 4 mm litz wire. Our typical
`resonant power Supplies are run at 24 volts, which allows for
`battery backup and Safe running and at 24 volts it can power
`about a 25 metre long primary inductive pathway, and about
`10-14 amperes at a 40 kHz frequency circulates in the cable
`when in operation. Using a higher Voltage allows longer
`primary inductive loops to be used. If an unusually short
`cable is used, its inductance may be boosted with a lumped
`inductance, rimmed to make the installation resonate at 40
`kHZ.
`
`EXAMPLE 3
`Our basic system may be embellished by providing for
`control of the output of the lamp units, either as a group or
`individually. Preferably this control is more than simply
`turning the entire Set on or off. One approach is to provide
`each lamp unit in an installation with control electronics that
`can detect Signals of Some Sort radiated from the primary
`conductor cable, because this cable is already functionally
`connected with all operational lamps.
`It is possible to Superimpose a message over the primary
`current, in the form of momentary variations of the ampli
`tude of the primary current, which can be Sensed within the
`or each lamp unit as changes in the operational Settings of
`the regulating mechanism. Coding of the amplitude could
`follow any convenient code, such as the letters of the ASCII
`coding System, or Morse code, or Some other System Such as
`those used in serial bus digital control, Such as the I°C bus.
`This requires a Small amount of complexity in each lamp
`unit that is capable of being addressed. Each “bit:” of the
`code would have to be sufficiently long in time to “catch”
`any lamp unit that at the time has shorted its inductive
`pickup coil, unless a Separate data Sensing arrangement was
`used. Information may be carried within a carrier frequency,
`Separate from the frequency of the power for inductive
`transfer.
`Variations of the phase of the primary current are another
`way to transmit data.
`
`Momentum Dynamics Corporation
`Exhibit 1015
`Page 010
`
`

`

`US 6,459,218 B2
`
`Acheap way of addressing lamp units is to make a variety
`of units each having a different resonant frequency. Then
`only those lamp unit that resonate at the frequency of the
`transmitted power can operate. If a resonant power Supply is
`used, it might be provided with subsidiary Switchable reso
`nating capacitors. By this means it is possible to create a
`travelling wave of flashing lights, for decorative or direc
`tional purposes.
`FIRE EGRESS INDICATION LAMPS
`This is-as a preferred example-a fire-exit indicating
`network, which when energised provides a chain of illumi
`nate