- United States Patent 5,629,678 Gargano , et al. May
13, 1997
-
- Personal tracking and recovery system
-
- Abstract
-
- Apparatus for tracking and recovering humans utilizes
an implantable transceiver incorporating a power supply and actuation system
allowing the unit to remain implanted and functional for years without
maintenance. The implanted transmitter may be remotely actuated, or actuated
by the implantee. Power for the remote-activated receiver is generated
electromechanically through the movement of body muscle. The device is
small enough to be implanted in a child, facilitating use as a safeguard
against kidnapping, and has a transmission range which also makes it suitable
for wilderness sporting activities. A novel biological monitoring feature
allows the device to be used to facilitate prompt medical dispatch in the
event of heart attack or similar medical emergency. A novel sensation-feedback
feature allows the implantee to control and actuate the device with certainty.
-
-
- Inventors: Gargano; Paul A. (154 Clifton St., Belmont,
MA 02178); Gilmore; David H. (Cayman Kai, KY); Pace; Frank A. (Ballston
Spa, NY); Weinstein; Lee (Somerville, MA) Assignee: Gargano; Paul A. (Belmont,
MA) Appl. No.: 371089 Filed: January 10, 1995
-
- Current U.S. Class: 340/573.4; 128/903; 340/539.1; 340/539.12;
340/825.49; 342/465; 455/100 Intern'l Class: G08B 023/00 Field of Search:
340/573,574,572,539,825.49 455/100 379/37-38 342/450,357,44,42,51 128/774,903,653.1,696
-
- Other References
-
- Dialog OneSearch Results, May 13, 1994.
-
- Primary Examiner: Mullen; Thomas
- Attorney, Agent or Firm: Hamilton, Brook, Smith &
Reynolds, P.C.
-
- Claims
-
-
-
- We claim:
-
- 1. A transceiver device implantable in a human body comprising:
-
- a triggerable radio frequency transmitter,
-
- a power source for powering said transmitter,
-
- triggering means for activating said transmitter,
-
- receiver means allowing the detection of an externally
generated information signal,
-
- an antenna for effectively radiating RF energy from said
transmitter to produce an identifiable RF signal for a period of time following
activation by said trigger means,
-
- said receiver means comprising an electromechanical device
having a binary output, a digital decoder for detecting predetermined time-encoded
information in the binary output of said electromechanical device and for
providing an electrical trigger signal representative of the presence of
such pre-determined information, and
-
- said trigger signal causing the activation of said transmitter.
-
- 2. The transceiver of claim 1, wherein said receiver
means additionally comprises a wave receiver for receiving a transmitted
wave, and
-
- said digital decoder is responsive to information in
an incoming transmitted wave for providing an electrical trigger signal
representative of the presence of the information.
-
- 3. The transceiver of claim 2, further comprising sensory
stimulus means for providing a noticeable stimulus to alert the person
in whom the device is implanted that all or part of said incoming transmitted
wave has been detected by said digital decoder.
-
- 4. The transceiver of claim 2, further comprising a charging
regulator for maintaining the power source used to power the transmitter
at a state of peak charge.
-
- 5. The implantable device of claim 1, wherein said receiver
means additionally comprises a sustainable power supply comprising means
for picking up periodically available external energy without external
electrical contact, storing said energy for use over time, such that the
resultant stored energy is sufficient to power the receiver means with
enough regularity to ensure proper detection of information on said incoming
signal.
-
- 6. The transceiver of claim 5 wherein said external energy
pickup comprises an inductive pickup, for converting magnetic energy to
electrical energy.
-
- 7. The transceiver of claim 6, wherein said inductive
pickup is placed close to the surface of the body of the individual in
which it is implanted.
-
- 8. The transceiver of claim 5 wherein said external energy
pickup comprises an electromechanical means for converting mechanical work
of the body into electrical energy.
-
- 9. The transceiver of claim 8, wherein said mechanical
work is supplied by muscle tissue in the body of the human in which the
device is implanted.
-
- 10. The device of claim 1, wherein said electromechanical
device includes threshold-detection circuitry.
-
- 11. The device of claim 1, wherein said signal decoder
allows input from more than one source of binary information.
-
- 12. The device of claim 1, further comprising means for
providing a perceivable stimulus in response to one output from said digital
decoder.
-
- 13. The transceiver of claim 12, wherein said receiver
means comprises analog circuitry for amplifying the electrical field associated
with the contraction of the human heart, and said digital decoder comprises
means for detecting the lack of a regular heartbeat.
-
- 14. The device of claim 1, wherein said signal decoder
provides a plurality of outputs in response to a plurality of different
pre-determined information patterns.
-
- 15. The transceiver of claim 1, further comprising sensory
stimulus means for providing a noticeable stimulus to alert the human in
whom the device is implanted that all or part of said externally generated
information signal has been detected by said digital decoder.
-
- 16. The transceiver of claim 1, further comprising sensory
stimulus means for providing a noticeable stimulus to alert the human in
whom the device is implanted that the all or part of said predetermined
information signal has been detected by said detector means.
-
- 17. The device of claim 1, wherein said digital decoder
allows input from more than one source of binary information.
-
- 18. A system for tracking and recovering humans in distress,
comprising;
-
- a plurality of triggerable transceivers implanted each
in a human being,
-
- each transceiver having a transmitter and a receiver,
any one of said transmitters of said transceivers uniquely triggerable
to transmit a radio frequency beacon signal after the receiver of said
transceiver receives a predetermined radio frequency information signal,
-
- a network of trigger transmitters and receivers, each
being sensitive to said radio frequency beacon signal and capable of deriving
positional information concerning the source of said beacon signal, and
-
- said trigger transmitters being capable of transmitting
a plurality of uniquely identifiable radio frequency information signals,
capable of uniquely triggering one of the plurality of implanted radio
transceivers.
-
- 19. The system of claim 18, further comprising a plurality
of mobile receivers sensitive to said radio frequency beacon signals for
providing finer positional accuracy in determining the location of the
source of said radio frequency beacon signals.
-
- Description
-
-
-
- BACKGROUND OF THE INVENTION
-
- The present invention relates, in general, to tracking
and recovery systems and systems for tracking and recovering humans. More
particularly, it discloses a system employing a self-powered, self-maintained
transceiver, small enough to be implanted in a human, for locating, tracking,
and recovering persons in distress, such as kidnap victims, people encountering
adverse circumstances while in the wilderness, victims of heart attacks
and the like.
-
- BACKGROUND OF THE INVENTION
-
- Various apparatus and techniques for tracking and locating
animate and inanimate objects are known in the art. Recently, international
legislation has established a satellite tracking system for locating downed
aircraft and distressed seagoing vessels. This system utilizes user-activated
transmitters operating at a frequency of 460 MHz, as spelled out in the
Code of Federal Regulations chapter 47 part 90. These inexpensive transmitters
are known as Emergency Position Indicating Radio Beacons (EPIRB's). The
associated satellite network is capable of locating a transmitting EPIRB
anywhere on the face of the globe. By international agreement, this system
is used only for distressed aircraft and seagoing vessels, and all other
potential uses are forbidden.
-
- U.S. Pat. No. 4,818,998 describes a vehicle tracking
and recovery system employing a transceiver (to be hidden within a motor
vehicle), and a network of fixed and mobile ground transmitters and receivers
to facilitate tracing and recovery of stolen vehicles. This system is presently
in wide use by LoJack Corporation in the United States. The system operates
at a frequency of 173.075 MHz, permanently assigned as a police radio service
frequency in 1992. The unit, mounted in an automobile, is continuously
operated as a receiver until such time as it is remotely activated, at
which time it transmits a radio beacon (similarly to the EPIRB system),
facilitating tracking and recovery. The tracking and recovery in the LoJack
system is accomplished through a network of ground based fixed and mobile
receiver units, which utilize field strength measurements and directional
receivers to locate the transmitter, as opposed to the timing and triangulation
methods used by the EPIRB system. The receiver in the automobile-mounted
unit draws its power from the vehicle battery, and utilizes a small local
rechargeable battery that powers the unit should the vehicle battery be
disconnected.
-
- U.S. Pat. No. 4,706,689, Issued to Daniel Man on Nov.
17th, 1987, describes a device designed to be implantable behind the ear
of a human. The device transmits a coded signal intended to enable tracking
of the person outfitted with the implanted device. The device operates
continuously, and is designed to be recharged through external contacts.
It is also designed to incorporate a biological monitoring function, such
as might facilitate out-patient monitoring.
-
- The above described devices all have limitations making
them unsuitable as systems for the widespread tracking and recovery of
humans. The EPIRB transmitter and Lojack transceiver are not miniaturized
to the point where implantation is practical. The techniques for manually
activating the EPIRB unit also make it unsuited for implantation. The LoJack
unit requires substantial power to be supplied continually from a vehicle
battery system, and unsuited for implantation from this point of view as
well.
-
- Daniel Man's implantable device is designed for continuous
operation, which places severe constraints on its transmission range, even
if it is only to be operated for a day at a time between battery recharges.
With a given level of background radio frequency noise, communication theory
can be used to calculate the minimum power consumption needed for detection
of an event within a given time to within a given certainty, at a given
distance from an omni-directional transmitter. The resultant average transmission
power is independent of whether the transmitter is pulsed or continuous.
Further problems arise with Man's system when a number of units are in
use in the same area. The tracking problem becomes prohibitively expensive
for many simultaneous units, and the malfunction of any unit can mask the
detectability of other units, or require significantly increased transmission
power levels for all units. Such a system would require a very expensive
closely spaced network of permanent tracking receivers with very costly
hardware capable of tracking multiple units at one time. A system where
transmitters are active all the time requires n times more bandwidth in
the radio spectrum than minimal-bandwidth system with only one transmitter
transmitting at one time. The availability of bandwidth could become quite
a problem if the Man system were put into wide use.
-
- In addition, the implanted unit would need to be recharged
(probably daily) through contacts brought out through the person's skin.
Such an arrangement presents a significant health hazard. In addition,
the need for regular recharging puts significant restraints on the person
using the device and also heightens the users awareness of the implanted
device, resulting in a less "free and natural" state of mind.
The complexity of the Man system could result in a significant level of
false alarms, and/or prohibitively high cost.
-
- The present invention contemplates improving upon the
features available in the aforementioned devices and makes possible a widespread
tracking and recovery system for humans in distress. The present invention
will benefit from novel features allowing it to remain implanted and functional
for many years. The device will remain in a dormant state until activated,
either by the person in whom it is implanted, or by remote means. Novel
means for powering and triggering the device will make recharging and battery
replacement unnecessary. The device meets the growing demand for a new
level of safety and peace of mind.
-
- Consequently, it is a general object of this invention
to provide a new means and method for locating, tracking, and recovering
humans in distress. Ideally, the device will bring peace of mind and an
increased quality of life for those who use it, and for their families,
loved ones, and associates who depend on them critically. Adults who are
at risk due to their economic or political status, as well as their children
who may be at risk of being kidnapped, will reap new freedoms in their
every-day lives by employing the device. Law enforcement agencies will
be able to more economically protect those at risk, those who would potentially
perpetrate acts of violence against individuals will be more effectively
deterred. Those who enjoy wilderness sports such as mountain climbing,
skiing, hang gliding, etc. will enjoy new freedom knowing that a rescue
mission can be dispatched to their exact location if they encounter trouble.
-
- A specific object of the invention is the rapid effective
recovery of individuals who have been kidnapped. A further object of this
invention is to afford peace of mind and increased quality of life to those
utilizing the invention, and to their loved ones and dependent associates.
It is a further object of the invention to make emergency aid readily available
to those at risk in remote or urban areas. It is a further object of the
invention to reduce the cost of rescue missions to remote areas. It is
further object of the invention to facilitate a highly reliable, minimal
cost, location and recovery system with flexible features. It is a further
object of the invention to facilitate rapid, automatic deployment of medical
personnel in the event of certain medical emergencies.
-
- This implantable tracking and recovery device makes possible
greatly increased safety for people in a variety of situations. This increased
safety leads to peace of mind and associated increased quality of life
not only for those utilizing the device but for concerned loved ones as
well. Four areas where this device will be seen to have significant impacts
are (1) safeguarding against kidnapping, and rapid recovery of victims;
(2) safety in wilderness sporting activities, where risk is inherent and
help is often not readily available; (3) personal safety in urban environments,
where one might encounter car-jackings, muggings, and the like; (4) medical
emergencies, such as heart attack or seizure.
-
- The lives of potential kidnap victims and their loved
ones will be significantly freed up by the peace of mind afforded by the
tracking device. Along with peace of mind, the homing device will offer
the possibility of a lifestyle that would otherwise be considered too risky.
In the event of a kidnapping, law enforcement officials could be expediently
dispatched for rapid recovery of the victim.
-
- The tracking device will offer safety in such activities
as hiking, mountain climbing, skiing, and camping in remote areas. Costs
of rescue missions will be dramatically cut because searching will not
be necessary. Lives will be saved because the time from when the emergency
occurs to when help arrives will be dramatically cut.
-
- The device will afford increased safety and peace of
mind for those in urban areas as well. The increase in gang violence, rapes,
muggings, and car jackings in recent years has generated significant increased
concern for personal safety. The use of the device will afford increased
peace of mind and will allow law enforcement to be more effective.
-
- Many lives could be significantly prolonged if help were
rapidly available in the event of a heart attack. Unfortunately, the individual
suffering the heart attack may not recognize the symptoms of the heart
attack (which may occur in sleep), and even if the symptoms are recognized,
the individual may be unable to summon help. The use of the device with
incorporated body-function monitoring capability allows help to be rapidly
dispatched, potentially saving the life of the user.
-
- SUMMARY OF THE INVENTION
-
- The system employs triggerable radio beacon transmitter
means designed to be implanted beneath the skin of an individual. Biological
monitoring in the device will provide means for rapidly dispatching help
in the event of a detectable medical emergency, such as a heart attack.
A unique sensation-feedback feature allows the user to control and trigger
the device with certainty, resulting in a more reliable, easily maintained
system. The device is hermetically sealed in a biologically inert container.
The device operates normally in a dormant state, and can be externally
triggered to transmit the homing beacon. There are numerous possible embodiments
of the trigger mechanism. In some embodiments of the trigger mechanism,
the device is designed to be remotely triggered. Such a feature is desirable
if the device is implanted in a small child who cannot be relied upon to
trigger the device. Remote triggering may also be desirable in instances
when an individual may be unconscious.
-
- In one remote triggering instance, a radio transmitter
may broadcast a coded signal to a receiver within the device. The receiver
is equipped with circuitry for recognizing the coded radio signal. In one
embodiment where the device is locally triggered, the device may be equipped
with an acoustic receiver designed to detect certain sounds or a predetermined
sequence of sounds in time, such as a note progression. In this case the
device would likely be triggered by the person in whom it is implanted,
for instance by humming a given tune. Immunity to false alarms may be provided
by making the sequence long or requiring it to be repeated in a certain
amount of time.
-
- In another embodiment, the device may be triggered by
monitoring a body function such as heart rate. If the victim were to experience
a heart attack, help would be automatically and expediently dispatched.
-
- If the device is triggered either by an external coded
radio signal or a coded acoustic signal, or by monitoring a body function
such as heart rate, the device incorporates a micro-power analog electronic
means such as a radio or acoustic receiver or electrocardiogram monitoring
circuitry, which runs off energy collected either from body muscle by electromechanical
means, or from an external charger through electromagnetic induction coupling.
-
- Other local triggering means not requiring a micro-power
receiver are also contemplated. In such a case the device may be triggered
by electromechanical means with a binary output, such as a mechanical switch.
Possible embodiments of such a triggering mechanism range from a simple
subcutaneous switch or combination of switches that actuate the transmitter
when pressed, to an actuator coupled to internal body muscle, combined
with digital circuitry designed to trigger the transmitter in response
to a timed sequence of actuations.
-
- It may be desirable in some implementations to include
capabilities for both local and remote triggering. The same individual
may desire the capability of local triggering in the event of an emergency
such as a car-jacking, mugging, or kidnapping, while desiring remote triggering
capability if for some reason the situation had rendered the individual
unconscious. It may also be desirable in some embodiments for the user
to be able to disable the remote-trigger feature.
-
- The device contains a power source capable of supplying
power for the transmitter for ample time to afford recovery of the individual
in distress. Once triggered, the device may transmit only for a predetermined
interval, allowing re-triggering later if the distressed individual is
not located, or if help takes some time to dispatch.
-
- The small size of the device makes it suitable for implantation
in young children as well as adults. The above and other features of the
invention including various and novel details of construction and combination
of parts will now be more particularly described with reference to the
accompanying drawings and pointed out in the claims. It will be understood
that the particular personal tracking and recovery system embodying the
invention is shown by way of illustration only and not as a limitation
of the invention. The principles and features of this invention may be
employed in varied and numerous embodiments without departing from the
scope of the invention.
-
- BRIEF DESCRIPTION OF THE DRAWINGS
-
- FIG. 1 depicts an overall schematic view of a system
for the tracking, locating, and recovery of humans embodying the features
of the invention and including an exemplary implantable triggerable transmitting
device, remote activation transmitter, several ground-based receiving antennae
and alternate satellite-based receiving antennae, mobile receiving unit,
and associated coordinating equipment, which combine to perform the locating
and tracking function.
-
- FIG. 2 is a schematic block diagram of an illustrative
implantable triggerable transmitter unit, including sensation feedback
feature, and several trigger implementations, which are used separately
or in combination in a given embodiment of the implantable device.
-
- DETAILED DESCRIPTION OF THE INVENTION
-
- Referring to FIG. 1, one of a plurality of persons, P.sub.1,
is equipped with an implanted transceiver device D.sub.1 from a plurality
of devices D. A plurality of triggerable transmitters T (only one of which
is shown in FIG. 1) transmit a coded trigger signal S.sub.1, which is picked
up by the receiver section of all implanted devices D (only device D.sub.1
being shown in FIG. 1). The receiver circuits in all devices D receive
the same coded trigger signal. However, the code in signal S.sub.1 uniquely
identifies device D.sub.1, and D.sub.1 alone responds to coded signal S.sub.1
by transmitting a locating-and-tracking signal S.sub.2. Signal S.sub.2
is received by at least one ground-based receiver, A.sub.1, A.sub.2, and
A.sub.3, of a plurality of receivers A, or at least one satellite receiver
including SR.sub.1, SR.sub.2, and SR.sub.3 of a plurality of receivers
R.
-
- Information from the ground-based receivers A or the
satellite receivers S are coordinated at a tracking and locating center
TLC. Equipment within the tracking and locating center TLC uses information
(for example phase, timing, field strength, etc.) of the received signals
to derive positional information about implanted device D.sub.1. Additional
positional information may be provided by a mobile receiver MR, which may
employ directional receiving means DR, and one or more antenna MA. The
mobile receiver MR may be used, for instance, to locate implantable unit
D.sub.1 within a building, a neighborhood, or a small area of wilderness,
facilitating cost effective recovery without having to map the face of
the globe precisely.
-
- Upon being triggered by signal S.sub.1, implanted device
D.sub.1 preferably transmits only for a brief interval long enough to get
a rough positional fix. When the mobile receiver MR has been dispatched,
or other rescue means have been readied, transmitter T would then re-activate
implanted device D.sub.1 for the second stage of the recovery.
-
- FIG. 2 is a mechanical and electrical schematic block
diagram of an exemplary implantable triggerable transceiver unit D.sub.1.
The entire unit D.sub.1 is housed within a sealed case and designated 39.
The case is preferably made from or covered with a biologically inert material
such as Teflon or Titanium. Several possible mechanisms are shown. Remote
radio receiving means comprise a receiving antenna 2 and micro-power radio
receiver/demodulator means 4. The triggering signal S.sub.1 is received
by antenna 2, and the resultant electrical signal is fed to the micro-power
radio receiver/demodulator means 4, which outputs a binary signal S.sub.3
to signal decoder means 6. The signal decoder means 6 monitors signal S.sub.3
over time, and upon detecting a certain pre-determined pattern, sends a
trigger signal S.sub.5 to timing circuit means 8. Timing circuit means
8 then applies a control signal S.sub.6 to a power switching means 7, causing
power switching means 7 to apply power from power source 14 to a beacon
transmitter 10, which may broadcast at different power levels, controlled
by signal decoder means 6.
-
- The beacon transmitter 10 operates in response to being
actuated by power source 14, and transmits the locating and tracking signal
S.sub.2 via transmitting antenna 12. Through the incorporation of proper
input protection circuitry on the micro-power receiver 4, it is possible
for receiving antenna 2 and transmitting antenna 12 to be one and the same.
These antennae are shown as being separate in FIG. 2 for functional clarity.
The micro-power receiver means 4 is powered by energy storage means 36.
Micro-power generating means 26 may derive power from some energy source
external to the implanted device.
-
- In the preferred embodiment, micro-power generating means
26 derives power from physical work done by muscle fibers in the body.
Body muscle 30 is connected (for instance, via suturing) to linkage 28.
Linkage 28 connects muscle 30 through a seal in case 39 to micro-power
transducing means 26. Case 39 is mechanically anchored to another body
structure (for instance muscle, tendon, bone, etc.) to afford an opposing
force to that exerted by muscle 30. Power transducing means 26 converts
the work of muscle 30 to useful electrical energy, which is fed to energy
conversion circuitry 32. Energy conversion circuitry 32 is provided to
most efficiently store the electrical energy derived from power transducing
means 26 in energy storage means 36. Energy storage means 36 serves as
an energy reservoir for micro-power circuitry 34. Micro-power receiver
4 may be implemented similarly to receiver sections used in miniature commercial
pagers. Power transducing means 26 may be a piezoelectric device (the preferred
embodiment), electromagnetic induction device (such as a moving magnet
generator), or the like. Linkage 28 is preferably sealed to case 40 with
a flexible membrane.
-
- Energy storage means 36 holds enough energy to sustain
micro-power circuitry in an operational state with enough regularity to
insure proper triggering of beacon transmitter 10 in response to trigger
signal S.sub.1. The duty cycle requirements of the availability of power
from energy storage means 36 may be traded off against the length of time
the activation signal S.sub.1 is sent out. In the preferred embodiment,
there is enough power available from energy reservoir 36 to power micro-power
receiver/demodulator means 4 100% of the time.
-
- Power-switching means 7 is shown as a field-effect transistor,
chosen in the preferred embodiment because it takes no static power to
keep turned on, yielding easy interface with micro-power circuitry, and
also allowing a high degree of integration onto a single chip. Signal decoding
circuitry 6 and timing circuitry 8 are preferably CMOS logic, in order
to draw minimal power. Timing circuitry 8 is preferably powered from power
source 14, in order that brief lapses in the availability of power from
energy storage reservoir 36 will not affect the timing of beacon transmitter
10.
-
- Signal decoder means 6 may be made capable of detecting
multiple codes to perform different functions, for instance to activate
beacon transmitter means 10 for different periods of time. A short-time
actuation might be desirable for an initial positional
- fix, and a long-time actuation might be desirable for
a final local recovery by a mobile receiver. It is desirable to have different
activation codes result in beacon transmitter 10 being energized at different
power levels, for instance a high power level for the initial positional
fix, where the receiving antennae may be far away, and a lower power level
during the final positional determination by a mobile receiver.
-
- Binary conversion means 38 converts the analog signal
derived from power transducing means 26 to a digital signal. In the preferred
embodiment, this enables body muscle 30 to be used to control the implanted
device as well as provide power to the device. Contractions of body muscle
30 cause alternating voltage signal S.sub.5 to be generated and applied
to energy conversion circuitry 32 and binary conversion means 38. For the
piezoelectric power transducing means of the preferred embodiment, binary
conversion means 38 may be implemented as a voltage divider means 24 followed
by Schmitt trigger means 22. Binary conversion means 38 is powered by energy
storage reservoir 36, in order to avoid draining the standby power source
14. The output of binary conversion means 38 feeds an input on signal decoder
means 6 with a digital signal, allowing signal decoder means 6 to be entirely
digital CMOS circuitry such as common in wristwatches, which can be made
to draw so little power that the drain on power source 14 would be inconsequential,
even over a number of years.
-
- Signal decoder 6 may provide different decoding functions
for data streams from different sources. For instance, signal S.sub.4,
derived locally, may be decoded to provide functions not accessible remotely,
such as shutting down micro-power receiving means 4. This may be desirable
if the user is worried about being locatable by an adverse party under
certain circumstances. Partial completion of the trigger code in data stream
S.sub.4 may be programmed to provide a perceivable sensation to the user,
for instance through vibrator means 20. This would provide means for "practicing"
triggering the device without actually sending out a signal indicating
an emergency. It is also possible to configure the device to provide the
same or different perceivable sensation through vibrator means 20 upon
activation of Beacon transmitter 10. This feedback would provide peace
of mind to the user, knowing that help was on the way. Various self-test
functions may be implemented through special codes recognized in signal
stream S.sub.4.
-
- Voltage monitor means 16 is provided to detect a low-energy
state of power source 14. Voltage monitor means 16 is preferentially powered
off energy reservoir 36, ensuring that the critical standby power source
16 is not drained by providing the voltage monitoring function. Voltage
monitor means 16 may also activate vibrator means 20 in such a way as to
provide a sensation uniquely indicating low power.
-
- It is contemplated that in one embodiment, energy reservoir
36 and power source 14 would be one and the same. This has not been done
in the preferred embodiment for three reasons: First, the most suitable
embodiment of power source 14 is deemed to be a chemical storage battery
with a long (perhaps 10 year) expected shelf life. This ensures that adequate
power for beacon transmitter 10 is available reliably, while taking very
little space. Second, regular "playing" with vibrator means 20
could, in such an instance, result in substantially draining power source
14 for some period of time. Third, implementing energy reservoir 36 with
a different type of energy storage device than 14 (for instance, implementing
36 as a capacitor) can allow for increased charging efficiency over the
relatively low electrochemical charging efficiency of many batteries.
-
- For very long term applications or to reduce the shelf
life requirements on power source 14, voltage regulator means 18 may be
provided to use surplus energy collected from power transducing means 26
to keep power source 14 optimally charged.
-
- It may be desirable to separate the receiving and/or
transmitting antennae 2 and 12 from the rest of the unit, in order to allow
the antennae to be closer to the surface of the body for more efficient
transmission and reception. Such mechanical alterations to the containment
of the device are within the scope of the present invention.
-
- It is also possible for the conversion circuitry 32 to
receive power from a source external to the body, such as an electromagnetic
induction source that might be placed close to the body on a regular basis
for purposes of recharging energy reservoir 36. In such an embodiment inductive
pickup means 40 receives electromagnetic energy from a source external
to the body. Such implementation is considered less desirable because it
affords the user less personal freedom, and results in a system which is
less robust overall.
-
- The drawings referred to in the specification are presented
in block diagram form. Numerous possible implementations of any given block
will be apparent to one skilled in the art. Any specific details referred
to are strictly by way of example. It will be readily apparent to one skilled
in the art that various substitutions and modifications can be made without
departing from the spirit of the invention.
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