Note: Descriptions are shown in the official language in which they were submitted.
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MEASURING HARVESTED ENERGY USING AN ULTRA-LOW DUTY CYCLE
MEASUREMENT SYSTEM
Related Applications
This application claims priority to U.S. Patent App. No. 62/311,114, filed on
March 21,
2016.
Technical Field
The present invention relates to access control systems including one or more
energy
source sensors and energy harvesters, and more specifically, to methods and
systems for
management and utilization of harvested energy to power access control devices
and
other system implementation.
Description of Related Art
Access control devices or electronic locks need to be powered from an energy
source,
typically a primary power source such as a chemical battery. As modern
electronic
devices significantly reduce power consumption, it is becoming plausible to
rely on
other sources of energy to power such devices, either as a primary power
source or as a
backup or supplement to another source of energy. One such source is energy
harvested from various environmental sources, and these sources of energy can
be
applied to an access control device using any one or a combination of their
effects and
can be utilized to provide power for the access control device, or can be used
in other
system implementation. Sources of energy other than environmental sources,
such as
electromotive or weak nuclear forces, despite utility for this purpose, are
not generally
adapted for use in access control systems. Therefore, a need exists for a
means to
manage and utilize various sources of harvested energy to power such devices
and
other system implementation.
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Disclosure of the Invention
Bearing in mind the problems and deficiencies of the prior art, it is
therefore an object
of the present invention to provide a system which optimizes available energy
sources
for use in access control systems.
It is another object of the present invention to provide a method for managing
harvested
energy in an access control system by monitoring available energy sources
using one or
more sensors to determine the amount of available energy.
A further object of the invention is to provide an improved method of managing
power
supply circuits in an access control system using harvested energy.
It is yet another object of the present invention to provide an improved
system for
harvesting energy from available energy sources for use in access control
systems.
It is still yet another object of the present invention to provide an improved
system and
method for measuring the amount of energy harvested in a capacitive storage
device
from available energy sources.
Still other objects and advantages of the invention will in part be obvious
and will in
part be apparent from the specification.
The above and other objects, which will be apparent to those skilled in the
art, are
achieved in the present invention which is directed to a system for managing
light
energy in an access control system, comprising an access control device
positioned in
an area of a building that will provide at least one light source, and at
least one light
sensor positioned on a surface of the access control device and receiving
light energy
from the at least one light source. An energy harvesting manager is coupled to
the at
least one light sensor, wherein the energy harvesting manager manages the
amount of
light energy received by the at least one light sensor. The system further
comprises an
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interconnect between the energy harvesting manager and the access control
device, and
the interconnect may comprise electrical, inductive, or optical connectivity.
The energy harvesting manager may measure the amount of light energy received
from
the at least one light source and determine whether the measured amount of
light
energy is above a predetermined threshold. The system may further include at
least one
energy harvester, and if the measured amount of light energy is above the
predetermined threshold, the energy harvesting manager may instruct the at
least one
energy harvester to convert the light energy into harvested energy. If the
measured
amount of light energy is not above the predetermined threshold, the energy
harvesting
manager may transmit a signal to another component in the access control
system to
adjust the amount of light energy available to the at least one light sensor
from the at
least one light source until the predetermined threshold is reached. The at
least one
energy harvester may be a photovoltaic cell fitted to the access control
device for
absorbing light energy received from the at least one light source and
converting the
light energy into harvested energy.
The energy harvesting manager may determine that a power level of the
harvested
energy is above a predetermined threshold, and the energy harvesting manager
may
power the access control device using the harvested energy.
The system may further comprise a secondary energy storage, and the energy
harvesting
.. manager may determine that a power level of the harvested energy is above a
predetermined threshold and charge the secondary energy storage using the
harvested
energy. The secondary energy storage may comprise at least one of a
rechargeable
battery and a capacitor.
The energy harvesting manager may transmit the amount of light energy received
by the
at least one light sensor to another of a plurality of components in the
access control
system for use in management of one or more power supply circuits.
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In another aspect, the present invention is directed to a method for managing
light
energy received from at least one light source by at least one light sensor in
an access
control system. The method comprises receiving light energy by the at least
one light
sensor, measuring the amount of light energy received by an energy harvesting
manager
interconnected with an access control device, and determining whether the
measured
amount of light energy is above a predetermined threshold. If the measured
amount of
light energy is above the predetermined threshold, the method comprises the
light
energy into harvested energy by at least one energy harvester. If the measured
amount
of light energy is not above the predetermined threshold, the method comprises
adjusting the amount of light energy available to the at least one light
sensor from the at
least one light source until the predetermined threshold is reached. The
amount of light
energy available to the at least one light sensor may be adjusted by opening
or closing a
window blind or shade to vary the amount of light entering an area in which
the at least
one light sensor is located. The at least one energy harvester may be a
photovoltaic cell
or cells fitted to the access control device for absorbing light energy
received from the at
least one light source.
The method may further comprise determining that a power level of the
harvested
energy is above a predetermined threshold, and powering the access control
device
using the harvested energy. The method may further comprise monitoring a power
level of a primary power source interconnected to the access control device,
determining that the power level of the primary power source has fallen below
a critical
threshold, and combining the harvested energy with energy drawn from the
primary
power source to power the access control device.
The method may further comprise determining that a power level of the
harvested
energy is above a predetermined threshold, and charging an energy storage
interconnected to the access control device using the harvested energy,
wherein the
energy storage is separate from a primary power source used to power the
access
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control device. In another embodiment, the method may comprise monitoring a
power
level of a secondary power storage, determining whether the power level of the
secondary power storage is above a predetermined threshold, and if the power
level of
the secondary power storage is not above the predetermined threshold, sending
a signal
by the energy harvesting manager to another component in an access control
system to
adjust the amount of light energy available to the at least one light sensor
from the at
least one light source until the predetermined threshold is reached, before
converting
the light energy into harvested energy by the at least one energy harvester
and charging
the secondary power storage using the harvested energy.
The method may further comprise, subsequent to measuring the amount of light
energy
received by an energy harvesting manager interconnected to the access control
device,
transmitting by the energy harvesting manager the measured amount of light
energy
received to another of a plurality of components in the access control system
for use in
management of one or more building power supply circuits.
In yet another aspect, the present invention is directed to a method for
managing energy
potential received from at least one energy source by at least one sensor
interconnected
with an access control device. The method comprises receiving energy potential
by the
at least one sensor, measuring the amount of energy potential received by an
energy
harvesting manager interconnected with the at least one sensor and the access
control
device, and determining whether the measured amount of energy potential is
above a
predetermined threshold. If the measured amount of energy potential is above
the
predetermined threshold, the method comprises converting the energy potential
into
harvested energy by at least one energy harvester. If the measured amount of
energy
potential is not above the predetermined threshold, the method comprises
adjusting the
amount of energy potential available to the at least one sensor from the one
or more
energy sources until the predetermined threshold is reached.
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The at least one energy source may comprise electromagnetic induction,
electrolytic-
metallic contact, metallic contact, semiconductor contact, triboelectric
contact or weak
nuclear force, and the method may further comprise the steps of determining
that a
power level of the harvested energy is above a predetermined threshold, and
powering
the access control device using the harvested energy.
In still yet another aspect, the present invention is directed to a method for
measuring
energy harvested from at least one energy source for use in an access control
system,
comprising providing an access control device adapted to be at least partially
powered
by energy harvested from at least one energy source; providing at least one
sensor
receiving energy from the at least one energy source; providing an energy
harvesting
manager coupled to the at least one sensor, wherein the energy harvesting
manager
manages the amount of energy received by the at least one sensor; providing a
capacitive storage device coupled to the energy harvesting manager, the
capacitive
storage device for storing energy harvested from the at least one sensor;
charging the
capacitive storage device to a voltage high threshold, V-HTH; applying a
reference load
to the capacitive storage device until the capacitive storage device
discharges to a
predetermined voltage value, Vole, the reference load having a predetermined
resistance value; determining a time constant, the time constant defined as
the length of
time required for the capacitive storage device to discharge to the
predetermined
voltage value, Vo/e; and determining an exact or near exact capacitance of the
capacitive storage device by comparing the time constant to the reference load
predetermined value, by the expression: C = RC / RL, where C = capacitance (in
farads), RC = time constant (in seconds), and RL = reference load resistance
(in ohms).
The method may further comprise discharging the capacitive storage device to a
voltage
low threshold, V-LTH; and determining an amount of energy used per charge
unloaded,
CnL, of the capacitive storage device by comparing the voltage high threshold,
V-HTH,
and the voltage low threshold, V-LTH, by the expression: CnL = (0.5 * C * (V-
LTH2 ¨
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V-HTH2)) / 3600, where CnL = energy (in watt hours), C = capacitance (in
farads), V-
LTH = voltage low threshold (in volts), and V-HTH = voltage high threshold (in
volts).
In another embodiment, the method may further comprise the steps of:
calculating a
charge time, CtnL, without applying the reference load, defined as the time
required to
charge the capacitive storage device to the voltage high threshold, V-HTH;
charging the
capacitive storage device using at least one pulse of current having a
duration of
between about 150 milliseconds and 500 milliseconds and determining the total
charge
time, CCt; estimating the amount of energy used per pulse capacitor charge,
PCC, by
the expression: PCC = (CCt/CtnL) * CnL, where PCC = energy (in Wh), CCt =
total
charge time (in seconds), CtnL = charge time no load (in seconds), and CnL =
charge
no load (in watt hours); and plotting the PCC on an exponential correlation
curve to
charge time.
Brief Description of the Drawings
The features of the invention believed to be novel and the elements
characteristic of the
invention are set forth with particularity in the appended claims. The figures
are for
illustration purposes only and are not drawn to scale. The invention itself,
however,
both as to organization and method of operation, may best be understood by
reference
to the detailed description which follows taken in conjunction with the
accompanying
drawings in which:
Fig. 1 is a block diagram showing an exemplary system for managing and
utilizing
harvested energy in an access control system, according to various embodiments
of the
present invention.
Fig. 2 is a block diagram showing a system for managing and utilizing
harvested light
energy in an access control system, according to an embodiment of the present
invention.
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Fig. 3 is an exemplary access control device including one or more light
sensors
positioned in an area that will provide one or both of artificial and natural
light sources.
Fig. 3A is a plan view of the access control device of Fig. 3, showing a light
sensor in
conjunction with a photovoltaic cell.
Figs. 4A and 4B are exemplary embodiments of a door with an access control
device
including one or more light sensors positioned on the interior (Fig. 4A) and
exterior (Fig.
4B) surfaces, respectively, of the door.
Figs. 5A and 5Bare exemplary embodiments of a door with an access control
device
including one or more light sensors in conjunction with photovoltaic cell(s)
positioned
on the interior (Fig. 5A) and exterior (Fig. 5B) surfaces, respectively, of
the door.
Fig. 6 is a process flow diagram showing the steps performed by the system of
the
present invention to manage and utilize light energy received from one or more
light
sources, according to various embodiments of the present teachings.
Fig. 7 is a block diagram of an exemplary energy harvesting circuit of the
present
invention.
Figs. 8 and 9 are top plan views of exemplary energy harvesting circuitry of
the present
invention.
Mode(s) for Carrying Out the Invention
In describing the embodiments of the present invention, reference will be made
herein
to Figs. 1-9 of the drawings in which like numerals refer to like features of
the invention.
Certain terminology is used herein for convenience only and is not to be taken
as a
limitation of the invention. For example, words such as "upper," "lower,"
"left," "right,"
"horizontal," "vertical," "upward," and "downward" merely describe the
configuration
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shown in the drawings. For purposes of clarity, the same reference numbers may
be
used in the drawings to identify similar elements.
Additionally, in the subject description, the word "exemplary" is used to mean
serving
as an example, instance or illustration. Any aspect or design described herein
as
"exemplary" is not necessarily intended to be construed as preferred or
advantageous
over other aspects or design. Rather, the use of the word "exemplary" is
merely
intended to present concepts in a concrete fashion.
The present invention is directed to systems and methods for managing and
utilizing
harvested energy to power access control devices and/or for other access
control system
implementation. Access control devices need to be powered from an energy
source,
typically a primary power source such as a chemical battery. As modern
electronic
devices significantly reduce power consumption, it is becoming plausible to
rely on
other sources to power such devices, either as a primary power source or as a
backup or
supplement to another source of energy. The types of energy available and
usable for
1 5 this purpose include energy harvested from the environment, such as
light energy, as
well as non-environmental sources such as electromotive forces or potentially
weak
nuclear forces. These sources of energy can be applied to an access control
device
using any one or a combination of their effects and can be utilized to provide
power for
the access control device, or can be used in other system implementation.
Aspects of the present teachings relate to an access control system including
one or
more energy source sensors and energy harvesting elements that can harvest
energy
from various identified sources to power an access control device or
electronic lock, or
for other system implementation. The energy harvesting elements are
interconnected to
a controller or energy harvesting manager which manages all energy harvesting
peripherals and may use the harvested energy for system implementation
including, for
example, to supply or supplement the energy necessary to power an access
control
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device. Environmental sources can include ambient or background sources of
energy,
examples of which include electromagnetic radiation (e.g., visible light,
infrared light,
radio waves, etc.), magnetic field, radiation, vibration, mechanical and
biomechanical
movement, heat, chemical reaction, pressure, airflow, and the like.
Referring now to Fig. 1, a block diagram of an exemplary access control system
of the
present invention is shown. The system 100 may generally comprise an energy
harvester or energy conversion cell or device 120, an energy harvesting
manager 150,
and an interconnection 160 to a controller for a lock or access control device
(not
shown), such as a door opener or closer. Energy harvesting manager 150 manages
all
energy harvesting peripherals and is capable of outputting constant energy to
the lock
controller. Energy harvesting manager 150 can receive and manage energy
absorbed or
harvested by energy conversion cell 120 from one or more identified energy
sources, as
described in further detail below, and can use the harvested energy to power
and/or
control the access control device, or for other system implementation. Energy
harvesting
manager 150 can manage energy harvested by energy conversion cell 120 by, for
example, monitoring the availability of harvested energy, conditioning the
harvested
energy, combining the harvested energy with energy from another source,
communicating with the lock controller, and the like. Energy harvesting
manager 150
can condition the harvested energy, for example, by rectifying, smoothing,
stepping up,
and/or stepping down the voltage of the harvested energy. In one or more
embodiments, the system 100 may include a voltage boost 140 that is optimized
for
interfacing with the connected lock controller or access control device.
Energy harvesting manager 150 may include a voltage converter, a regulating
circuit,
rectifiers and matching networks, a power conditioner, a power
switch/combiner,
and/or any other hardware or software configured to provide power
continuously,
periodically, or on-demand. Energy harvesting manager 150 may be
interconnected to
a secondary energy storage 130 and can store the harvested energy in energy
storage
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130, or can draw energy from energy storage 130 to supplement or provide the
energy
needed to power the access control device. Energy harvesting manager 150 can
control
the continuous, periodic, or sporadic charging or discharging of energy
storage 130.
Secondary energy storage 130 may be a rechargeable battery, a capacitor, a
combination of a battery and a capacitor, or may be any other rechargeable
energy
storage known to one skilled in the art. Energy harvesting manager 150 can
divert and
regulate the voltage and/or amperage of the harvested energy to charge energy
storage
130, and can draw power from energy storage 130 as needed to power the access
control device.
Fig. 7 depicts a block diagram of an exemplary energy harvesting circuit of
another
embodiment of the present invention. As shown in Fig. 7, the system may
comprise two
primary power sources and one secondary power source. The primary sources may
be
defined as V-AUX and V-BATT. V-AUX may be designed to operate from a voltage
source of 9.5-24V and may be a low leakage source input which can be sourced
with
primary battery power, secondary battery power, or hardwired operation. V-BATT
may
be designed to operate from a voltage source of 5.2-9.5V and may be a low
leakage
source input which is designed to be primarily used with alkaline batteries.
The primary sources, V-AUX and V-BATT, may be diode OR'd together with diodes
that
are designed to prevent reverse leakage of no more than luA. The resulting
diode OR'd
output to 3V3-D1 can be switched to either open or closed. The switch should
be
opened only if there is sufficient energy harvested and stored in V-AUX-
Special to
supply the entire system. This scenario will occur if the V-AUX-Special is in
a surplus
state where it is producing more energy than can be used from the 5V2-D2 rail
alone.
The secondary source may be defined as V-AUX-Special. V-AUX-Special may be
designed to operate from a voltage source of 2.75-5.2V. V-AUX-Special or 3V3-
D1 can
be used to source power to 5V2-D2 with a switch determining the selected
source. In
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some embodiments, the 3V3-D1 is used to source power to 5V2-D2. In other
embodiments, V-AUX-Special may be used to source power to 5V2-D2 only if there
is
sufficient harvested energy available.
Status indication of switch state is provided to an interrupt via Harvest Ctrl
net.
Additionally, forced options are available for short term testing via Harvest
Ctrl and
3V3 Ctrl nets.
The 5V2-D2 regulation may use a hysteric power supply, which boosts an input
of from
2.75-5.2V to about 5.135-5.35V. The boost regulation occurs in short pulses of
about
100mA with durations from 150ms to about 500ms or more. These short pulses
charge
two balanced super-capacitors arranged in series. The super-capacitors store
the energy
with a 2-3uA leakage for about 1 hour when the system is in a quiescent state.
The
stored energy in the capacitor may be designed to be utilized for short high
current
pulse requirements to drive motors and RF devices. The supply is designed to
supply
current of up to 1A at 5.2V for durations of 150ms and 150mA with no duration
limit,
as shown in the chart below.
Current @5.3V Supplied By Hystaric Supply as a Function of Pulse Duration
3
.............................................................. 1
05IJ
cil 0.251
a.)
0 08
0.06
Pulse Duration in (s)
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The 5V2-D2 may be used to power an access control device. The 5V2-D2 may also
be
diode OR'd into the 3V3-D1 regulation input and can be used to supply the
entire
system during an energy harvest switch over or to supply energy for power fail
operation. The 5V2-D2 regulation can be forced to an off state for testing
purposes. The
5V2-D2 regulation enable pin is defaulted to on, but is controlled by the
hysteric
comparator. The status of the enable pin is connected to an interrupt input
and is
intended to be used for energy monitoring.
The V-AUX-Special and 5V2-D2 with super-capacitor buffer have features to
check their
voltage levels and both have reference test loads to verify their storage
capacity.
.. In accordance with the present invention, measuring harvested energy cannot
be fully
measured by only measuring utilized energy. This is because it is possible to
produce or
harvest more energy than the system utilizes. The total energy harvested may
be
measured and reconciled only if there is sufficient storage to store excess
energy. If
there is insufficient storage for excess energy, then the system will dispose
of unwanted
.. energy. It is noted that in various embodiments of the invention, if there
is more energy
than needed for one power source, then the excess energy may be used to power
a
second power source. If there is still more energy than can be utilized, it
will be
removed from the system and not counted.
In one or more embodiments, the secondary energy storage of the present
invention
.. may be a capacitive storage device, such as a super capacitor, lithium-
capacitor or other
similar device. To measure harvested energy in capacitive storage devices, it
is first
necessary, for calibration purposes, to determine the size of the energy
capacitance, as
capacitance components are defined as having a specific range of capacitance
plus or
minus a percentage of the nominal capacitance. Capacitance refers to the
ability of a
.. capacitor to store charge, and is the measurement used to indicate how much
energy a
particular capacitor can store. The calibration concept is based on the time
required to
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charge the capacitor under a known load and the time it takes to discharge the
capacitor
under a known load.
In accordance with the present invention, to measure the exact or near exact
capacitance of the capacitive storage device, a reference load 350 is applied
to the
capacitance and the rate of change in the voltage over time is defined. As
shown in Figs.
7 and 8, such reference loads for the method may be defined as 'V-AUX Special
Load
Test' and '5V2-D2 Load Test', and may be on the order of 1000 Ohms. It should
be
understood by those skilled in the art that a 1000 Ohms test load is described
for
exemplary purposes only, and that the present invention is not intended to be
limited to
such values. It is proposed that because of small changes in voltage over time
for some
reference loads, that a statistical method using linear regression be used to
ensure the
best quality of the measurements.
In accordance with a method of the present invention, determination of the
exact or
near exact capacitance of the capacitor should occur immediately after the
capacitive
storage device has been charged. The initial voltage Vo or 'V-HTH' (voltage
high
threshold) is recorded as the voltage discharge starting point. Once the
initial voltage Vo
or V-HTH is established, the 'V-AUX Special Load Test' or '5V2-D2 Load Test'
reference load 350, such as 1000 Ohms, is applied until the voltage of the
capacitor
discharges to a value equal to Vo/e or 1/e of its initial value. The amount of
time to
reach Vo/e is equal to the Time Constant (RC). The point at which the
capacitor is fully
discharged is known as the 'V-LTH' (voltage low threshold). An exemplary graph
depicting the voltage discharge is shown below.
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Vo
Vole
RC-Time Constant (s)
To calculate the size of the capacitor, the time constant is divided by the
load resistance
of the reference load 350, shown by the expression: C=RC/LR, where C is the
capacitor
size, RC is the time constant and LR is the reference load resistance.
Once an exact or near exact measurement of the capacitive storage is defined,
the
amount of energy that is used in the system in real-time may be determined by
measuring quantized energy charging. This may be accomplished by measuring the
charge time for a 'Super-Cap Buffer,' as shown in Fig. 7. Fig. 8 depicts an
exemplary
circuitry of the present invention including a 'Super-Cap Buffer' 330. The
energy used
per charge unloaded is defined as J = 0.5 x C x (V-LTHA2 ¨ V-HTHA2), where J
is the
energy used per charge in joules. To convert to Wh (watt hour), J is divided
by 3600, to
reach the CnL or 'Charge no Load' value in Wh.
The time it takes to charge the capacitor is then measured. To charge without
a load, it
is necessary to first apply the reference load until the V-LTH is met. The
total charge
time (in seconds) is defined as the CtnL or 'Charge time no Load'. The CnL and
CtnL
values may be used to estimate the total energy used in the system, including
if there is
a load or not. To calculate the total energy used, the measured 'Capacitor
Charge Time'
or CCt each time a charge occurs is divided by the CtnL and multiplying the
result by
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the CnL to determine the 'Pulse Capacitor Charge' or PCC, where PCC=(CCt/CtnL)
x
CnL.
The system-utilized energy or the energy used to charge the 'Super-Cap Buffer'
330 (i.e.,
'Pulse Capacitor Charge' or PCC) has been shown in practice to be an
exponential
correlation curve to charge time. This implies that as charge time increases,
then energy
added to the system increases at an exponential rate, where the rate of
increase per unit
time is imperially defined. Each time the charge occurs, it is assigned a
value of energy
and added to a running count in one of two registers, one for the battery (V-
AUX) and
the other for the secondary storage 130 or 'V-AUX SPECIAL' (Fig. 7). Energy
that had
not been utilized from the 'V-AUX Special Boost Charger' or the energy
harvesting
secondary source 130 is then reconciled using a delta voltage per delta time
measurement, minus the energy that had been utilized and counted. This
measurement
can occur daily or weekly.
One major source of energy waste is idle listening, which is a dominant factor
in sensor
network applications such as that of the present invention. A known approach
to
reducing energy lost to idle listening is to lower the radio duty cycle by
turning the
radio off part of the time. Duty cycle may be defined as the ratio between
listen time
and a full listen/sleep interval. To keep the abstraction of a fully connected
network,
many networks use duty cycling. Three approaches are generally used: time
division
multiple access (TDMA), scheduled contention, or low-power listening. Further,
scheduling reduces energy cost by ensuring that listeners and transmitters
have a
regular, short period in which to rendezvous and can sleep at other times.
The benefit to the system of the present invention is that the energy
measurement only
occurs during a 'Super-Cap Buffer' 330 charge, thus the processor time can be
limited to
a few milliseconds per day or less. Thus, the energy burden of doing energy
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measurement may be in the nano ampere (nA) range for the subsystem and
applicable
to ultra-low duty cycle power requirements.
Energy harvesting manager 150 can also manage harvested energy by switching
between the harvested energy and energy from another source to power the
access
control device, such as a primary power source 105, e.g., a chemical battery
or mains
power, based on the availability of the harvested energy and power demands of
the
access control device. For example, energy harvesting manager 150 can switch
to
harvested energy and rely on the harvested energy to power the access control
device
when energy harvesting manager 150 determines that a power level of the
harvested
energy, which may be stored in secondary energy storage 130, is above a
threshold.
Energy harvesting manager 150 can determine the power level based on the
harvested
energy's potential (e.g., voltage), flow rate (e.g., amperage), and/or power
(e.g.,
wattage). For another example, energy harvesting manager 150 can switch to a
non-
harvested source of power, such as chemical batteries or mains power 105, to
power
.. the access control device when energy harvesting manager 150 determines
that the
power level of harvested energy falls below a threshold.
According to various embodiments, the system of the present invention is
capable of
absorbing energy from a variety of identified energy sources, including
environmental
sources, such as visible light, electromotive sources or weak nuclear forces,
and
converting the absorbed energy into another form of energy, for example,
electromagnetic radiation to electricity, mechanical (e.g., vibration,
pressure, motion,
etc.) to electricity, heat to electricity, magnetic field to electricity,
chemical reaction to
electricity, and the like. Examples of electromotive forces available and
usable to power
the access control device include electromagnetic induction, electrolytic-
metallic
contact, metallic contact, semiconductor contact, or triboelectric contact, as
described
in more detail below. Alternatively, a weak nuclear force, e.g., radioactive
decay, can
result in spontaneous heat creation which can create power which can be
converted
Date Recue/Date Received 2021-08-20
-18-
into a useable potential to produce a charge to directly source a power supply
or charge
a secondary power storage in an access control system.
In one or more embodiments of the access control system of the present
invention,
electromagnetic induction may be utilized to either transfer power to the
access control
device directly through a conductor or through coupling. An electrical
generator, such
as a dynamo, may be used to produce a direct current flow that connects
directly to the
access control device. The mechanical force used to drive the dynamo may be
linear or
angular momentum, and the power may be converted into a useable potential by
energy conversion cell 120 and utilized by energy harvesting manager 150to
produce a
charge in secondary power storage supply 130 or to directly source a power
supply,
e.g., to power the lock or access control device directly. Energy harvesting
manager 150
may further communicate with the lock controller or access control device and
the
interconnection 160 between the energy harvesting manager and the lock
controller
may be electrical, inductive, optical, or any other method known to one
skilled in the
art. The access control system may further include an energy source sensor 110
interconnected with energy harvesting manager 150 for higher level management
of the
energy source and its utility.
In another embodiment, inductive coupling transformers may be used to induce
direct
transfer of energy between two or more circuits through electromagnetic
induction. A
varying current in the transformer's primary winding creates a varying
magnetic flux in
the core and a varying magnetic field impinging on the secondary winding. The
varying
magnetic field at the secondary winding induces a varying electromotive force
(emf) in
the secondary winding, and the power may be converted into a useable potential
by
energy conversion cell 120and utilized by energy harvesting manager 150 to
similarly
produce a charge in secondary power storage supply130 or to directly source a
power
supply for the lock or access control device.
Date Recue/Date Received 2021-08-20
-19-
In still another embodiment, the system may be capable of sensing a wireless
energy
transfer, such as through near-field or far-field RF. Near-field RF may be a
reactive near
field and/or radiative near field. In reactive near field, either E or H
fields dominate;
whereas in radiative near-field, there are no reactive field components. The
near-field
radiative or reactive power can be transmitted or absorbed up to a range of
two times
the wavelength. The transmitted power may be converted into a useable
potential by
energy conversion cell 120and utilized by energy harvesting manager 150 to
produce a
charge in secondary power storage supply 130 or to directly source a power
supply. In
far-field RF, radiation decreases as the square of distance and absorption of
the radiation
does not feed back to the transmitter. The far field RF is dominated by E and
B fields.
Energy can be transmitted over distances that are two times the wavelengths.
The
radiated power may be converted into a useable potential by energy conversion
cell
120 and utilized by energy harvesting manager 150to similarly produce a charge
in
secondary power storage supply 130or to directly source a power supply for the
lock or
access control device.
In other embodiments of the present invention, a device for inducing
electrolytic-
metallic or metallic contact may be coupled to the access control system to
provide a
power source. Electrolytic¨metallic contact from chemical sources, such as
batteries or
fuel cells, may be used to power the access control device as a time-released
power
source or power storage device. Batteries, through redox reactions, may be
used as a
primary power source, and may be in cell form and common types such as
Alkaline,
Lithium Ion, and Nickel Metal Hydride. Alternatively, fuel cells may be a
primary
power source that over timed releases may be used to produce a charge in
secondary
power storage supply130 or to directly source a power supply. In one or more
embodiments, a device inducing metallic contact coupled to the access control
system
may be utilized to release or transduce a potential from a metallic to
metallic contact,
such as in thermoelectric/pyroelectric contact resulting in the Seebeck
effect, e.g.,
Date Recue/Date Received 2021-08-20
-20-
conversion of temperature differences directly into electricity. In an
embodiment of the
present invention, a thermoelectric device creates voltage when there is a
temperature
gradient between metallic to metallic contacts, and this conversion of heat to
electricity
can be used as a power source. The power may be converted into a useable
potential
by energy conversion cell 120 and utilized by energy harvesting manager 150 to
produce a charge in secondary power storage 130 or to directly source a power
supply
for the lock or access control device.
In still other embodiments of the present invention, a device for inducing
triboelectic
contact may be coupled to the access control system to provide a power source.
Generally, if two different insulators are placed together or rubbed together,
one of the
two insulators will acquire a negative charge and the other will acquire an
equal
positive charge. When the two insulators are pulled apart, a potential is
produced. This
potential can be used to generate power, which may be converted into a useable
potential by energy conversion cell 120 and utilized by energy harvesting
manager 150
to similarly produce a charge in secondary power storage 130 or to directly
source a
power supply for the lock or access control device.
In still yet other embodiments of the present invention, the system may
utilize
semiconductor contact, e.g., a metallic contact with a semiconductor material,
or two
different semiconductors that are placed in contact, to provide a power
source.
Generally, when a metal contacts a semiconductor material or when two
semiconductors are placed in contact, one material becomes slightly positively-
charged
and the other slightly negatively-charged. In materials, for example, with a
direct band
gap, if a bright light is aimed at one part of the contact area between the
two
semiconductors, the voltage at that spot rises and electric current will
appear. One such
example is the piezoelectric effect, e.g., mechanical stress or pressure,
wherein an
electrical charge accumulates in certain solid materials in response to
applied
mechanical stress. The power can be converted into a useable potential by
energy
Date Recue/Date Received 2021-08-20
-21-
conversion cell 120 and utilized by energy harvesting manager 150 to produce a
charge
in secondary power storage 130or to directly source a power supply for the
lock or
access control device.
Another such example of semiconductor contact is the photovoltaic effect. In
various
.. embodiments of the present invention, the access control system may utilize
solar cells
or photovoltaic cells to convert and/or harvest light energy into useable
potential. Solar
cells are, in general, a semiconductor to semiconductor contact with a direct
band gap
between the materials that is optimized to cause flow between the materials
when solar
or sun light spectrums are aimed at the point of contact. At this point of
contact, light
energy is converted into electrical energy. Photovoltaic cells use the same
principals as
solar cells, but the spectrums are optimized from shorter spans. The light
energy power
can be converted into a useable potential by energy conversion cell 120 and
utilized by
energy harvesting manager 150 to produce a charge in secondary power storage
130 or
to directly source a power supply for the lock or access control device.
The system of the present invention may include one or more harvesters capable
of
harvesting energy from one source or multiple harvesters capable of harvesting
energy
from one or more sources. For example, the system may include a photovoltaic
cell, an
array of photovoltaic cells, a photovoltaic cell and a piezoelectric
transducer, an array
of photovoltaic cells and a piezoelectric transducer, and the like. In
configurations
where the system includes multiple harvesters, energy harvesting manager 150
can
monitor the availability of energy being harvested by each harvester,
condition the
energy being harvested by each harvester, switch between or combine the energy
being
harvested by each harvester to the power access control device, and the like.
Furthermore, in configurations where the system includes multiple types of
harvesters
each capable of harvesting energy from a different environmental source,
energy
harvesting manager 150can monitor the availability of energy being harvested
by each
type of harvester, condition the energy being harvested by each type of
harvester,
Date Recue/Date Received 2021-08-20
-22-
switch between or combine the energy being harvested by each type of harvester
to the
power access control device, and the like.
Fig. 2 depicts in block diagram an exemplary access control system of the
present
invention which utilizes harvested photovoltaic energy. The system 200 is
substantially
identical to that described above for managing and utilizing energy harvested
from
electromotive or weak nuclear forces, and may comprise a light sensor or
sensors 210, a
photovoltaic cell or cells 220, a secondary storage device 230, an energy
harvesting
manager 250, a primary power source 205, e.g. conventional building AC or DC
power
or a battery, and an interconnection 260 to a controller for a lock or access
control
device, such as a door opener or closer (not shown). The photovoltaic cell or
cells
220may be connected to the energy harvesting manager, and are used to absorb
light
energy from one or more identified light energy sources, as described in
further detail
below.
The energy harvesting manager 250 manages all energy harvesting peripherals
and is
.. capable of outputting constant energy to the lock controller or access
control device.
Energy harvesting manager 250 can receive and manage energy absorbed or
harvested
by photovoltaic cell or cells 220 from one or more identified light energy
sources, and
use the harvested energy to power and/or control the access control device, or
for other
system implementation, as described in further detail below. Energy harvesting
manager
250 can condition the harvested light energy, for example, by rectifying,
smoothing,
stepping up, and/or stepping down the voltage of the harvested energy. In one
or more
embodiments, the system 200 may include a voltage boost 240 that is optimized
for
interfacing with the connected lock controller or access control device.
Referring now to Fig. 3, an access control device or electrically controlled
lock 1000 is
.. fitted with a light sensor 210 and placed in a room or other area of a
building that will
provide at least one identified light source300, 400. As shown in Fig. 3, the
light
Date Recue/Date Received 2021-08-20
-23-
source may be an artificial light source, such as overhead 1ighting300, or a
natural light
source, such as solar or sunlight 400, or both. The amount of natural light
may be
controlled by, for example, adjusting the position of blinds or window shade
270 which
determine the amount of light 400 that reaches the light sensor 210 and
optional
photovoltaic cell or cells 220 (Fig. 3A). The light source's intensity, angle
of incidence,
spectrum and duration may be variable, and the light sources may be inside or
outside
of the visible spectrum. In an embodiment of the present invention, the light
sensor or
sensors may be fitted to either the interior-facing, i.e., inside a room (Fig.
4A) or
exterior-facing, i.e., outside a room (Fig. 4B) surface of the lock 1000.
The light sensor 210 may use pyranometer, solar, irradiance curves or other
irradiance
curves, such that a comparable energy input as seen by a one-junction or more
photovoltaic cell(s) can be determined. The light sensor 210 may be fed into
an energy
harvesting manager 250, as described above, where information obtained from
the light
sensor can either be used locally, used and stored locally, or transmitted to
a different
component in the access control system where it can be used and stored. The
resulting
information obtained from the light sensor 210 may be used for management of
power
supply circuits or other system implementation. For example, the light source
information may be used for building management to help ensure that a light
source or
sources is/are appropriate for a defined area, or may be used for diagnostic
purposes,
such as determining trends for the lock and to determine if the lock can be
used with a
photovoltaic power source cost effectively, e.g. the light sensor 210 provides
the ability
to sense and measure how much light energy is available to use, which measured
quantity may be used to determine if harvesting the light energy, such as by
using a
photovoltaic cell or cells 220, is possible and/or advisable. The light sensor
210 may
also be retrofitted to an existing lock or access control device and used to
determine
how efficient energy harvesting has been on pre-existing hardware. The light
sensor(s)
210 may be optimized using methods to focus light from one or more sources,
and/or
Date Recue/Date Received 2021-08-20
-24-
may be optimized to determine from which source or sources the light energy is
coming from. Implementations of the present invention may be for access
control
devices or electrically controlled locks that do not include photovoltaic
cell(s), as
described above, or for locks that include a light sensor in conjunction with
photovoltaic cell(s) for harvesting some or all of the light energy detected
by the light
sensor.
Referring now to Figs. 5A and 5B, embodiments of the present invention
including a
light sensor or sensors 210 in conjunction with a photovoltaic cell or cells
220 are
shown. As shown in the Figures, the photovoltaic cell or cells may be fitted
to either
.. the interior-facing, i.e., inside a room (Fig. 5A) or exterior-facing,
i.e., outside a room
(Fig. 5B) surface of the lock 1000, and may be on a permanent surface of the
lock, as
shown, or on a removable part of the lock. The photovoltaic cell or cells may
be thin
film or otherwise, and may be constructed of either single or multi-junction
cells that
give the ability to be optimized for either artificial light sources or
natural light sources
or both, or used to increase efficiency of energy conversion. In an
embodiment, the
light sources that are used are generally comprised of visible light, but
light outside this
spectrum is not excluded. The photovoltaic cell or cells 220may be designed to
be
optimized to maximize energy received from either natural or artificial light
sources by
setting an angle of incidence with respect to their light sources. Methods to
focus light
from one or more sources may be used to optimize utility of available light
sources. For
implementations of a lock with a light sensor and a photovoltaic cell or
cells, as shown
in Figs. 5A and 5B, the light sensor 210may be used to manage and optimize the
efficiency of the energy harvesting from the light sources. In certain
embodiments, the
implementation of a light sensor with a photovoltaic cell and the power supply
may be
used in a larger system that may potentially control sources of light, such as
issuing a
system warning to ensure that window blinds or shades are left open or opened
to a
certain degree for a specified period of time to help recharge a secondary
energy
Date Recue/Date Received 2021-08-20
-25-
storage, as described above. Such blinds or shades 270 are shown in Fig. 3 and
may be
controlled by energy harvesting manager 250 to open or close the blinds or
shades to a
desired degree to control the amount of natural light 400 that reaches
photovoltaic
cell(s) 220.
Fig. 6 illustrates an exemplary methodology and/or flow diagram of processing
500
performed by the system of the present invention to manage and utilize light
energy
harvested from identified energy sources in accordance with embodiments of the
present invention. In various embodiments, one or more components of the
system,
such as energy harvesting manager 250, can perform processing 500, or other
similar
processes to manage energy harvested from one or more identified energy
sources to
power an access control device or for other system implementation. For
simplicity of
explanation, the methodologies are depicted and described as a series of acts.
It is to be
understood and appreciated that the subject innovation is not limited by the
acts
illustrated and/or by the order of acts. For example, acts can occur in
various orders
and/or concurrently, and with other acts not presented and described herein.
Furthermore, not all illustrated acts may be required to implement the
methodologies in
accordance with the claimed subject matter. In addition, those skilled in the
art should
understand and appreciate that the methodologies could alternatively be
represented as
a series of interrelated states via a state diagram or events. Additionally,
it should be
further appreciated that the methodologies disclosed hereinafter and
throughout this
specification are capable of being stored on an article of manufacture to
facilitate
transporting and transferring such methodologies to computers. The term
article of
manufacture, as used herein, is intended to encompass a computer program
accessible
from any computer-readable device, carrier, or media.
In various embodiments, 5y5tem200 can perform processing 500, as shown in Fig.
6, to
manage and utilize light energy provided by one or more identified light
sources. At
step 510, energy harvesting manager 250 can determine whether or not light
energy is
Date Recue/Date Received 2021-08-20
-26-
being received by at least one light sensor 210. In configurations where the
system
includes more than one light sensor, energy harvesting manager 250 can monitor
the
availability of light energy being received by each, some, or all of the light
sensors 210.
Next, at step 520, if energy harvesting manager 250 has determined that no
light sensor
is receiving light energy, then processing 500 can either return to step 510
or terminate.
Alternatively, if energy harvesting manager 250 has determined that light
energy is
being received by at least one light sensor, then processing 500 can proceed
to step
530. At step 530, energy harvesting manager 250 measures the amount of light
energy
received by the one or more light sensors 210 and may either use the
information
locally, store the information locally for later use, or transmit the
information to another
component in the system where it can be used and/or stored.
At steps 540 and 550, energy harvesting manager 250 can determine whether or
not a
potential or power level (e.g., voltage, amperage, and/or wattage) of the
light energy
received is above a threshold, and determine whether there is sufficient light
energy
available to harvest the energy. Energy harvesting manager 250 can use this
measured
quantity to optimize the efficiency of the energy harvesting from its light
sources 210.
At step 570, if energy harvesting manager 250 has determined that the measured
amount of light energy received is not above a threshold, light sensors 210
may be
optimized by transmitting a signal from energy harvesting manager 250 to
another
component in the access control system to focus light from one or more light
sources by
adjusting the amount of light energy available to at least one light sensor,
for example,
by adjusting the position of window blinds or shades 270 in a room (Fig. 3).
Processing
500 may then return to step 530 and repeat steps 530 through 550 until the
potential of
the light energy received is above a threshold, or processing 500 may
terminate.
At step 560, energy harvesting manager 250 can harvest some or all of the
available
light energy using one or more energy harvesters, such as one or more
photovoltaic
cells 220, and manage the harvested energy. In configurations where the system
Date Recue/Date Received 2021-08-20
-27-
includes multiple harvesters, energy harvesting manager 250 can monitor the
power
level of energy being harvested by each, some, or all of the harvesters.
Energy
harvesting manager 250 can manage the harvested energy by conditioning the
harvested energy, such as by rectifying, smoothing, stepping up, and/or
stepping down
the voltage of the harvested energy. Energy harvesting manager 250 can also
manage
the harvested energy by combining the harvested energy with energy from one or
more
other sources, such as a primary power source, e.g., a battery, for powering
an access
control device. In configurations where the system includes multiple
harvesters, energy
harvesting manager 250 can combine the energy harvested by some or all of the
harvesters. Energy harvesting manager 250 can further manage harvested energy
by
switching between the harvested energy and energy from another source, such as
a
primary power source, to power an access control device based on the
availability of
the harvested energy and power demands of the access control device. In one or
more
embodiments, energy harvesting manager 250 can further manage harvested energy
by
using harvested energy to charge a secondary energy storage, such as a
rechargeable
battery or capacitor, which can then be used to power an access control device
directly
or to supplement a primary power supply. Finally, at step 580, energy
harvesting
manager 250 can use the harvested energy to power an access control device
and/or for
other system implementation, and then processing 500 can terminate.
.. The foregoing description is illustrative, and variations in configuration
and
implementation may occur to persons skilled in the art. For instance, the
various
illustrative logics, logical blocks, modules, and circuits described in
connection with the
embodiments disclosed herein can be implemented or performed with a general
purpose processor, a digital signal processor ("DSP"), an application specific
integrated
circuit, a field programmable gate array or other programmable logic device,
discrete
gate or transistor logic, discrete hardware components, or any combination
thereof
designed to perform the functions described herein. A general-purpose
processor can be
Date Recue/Date Received 2021-08-20
-28-
a microprocessor, but, in the alternative, the processor can be any
conventional
processor, controller, microcontrol ler, or state machine. A processor can
also be
implemented as a combination of computing devices, e.g., a combination of a
DSP and
a microprocessor, a plurality of microprocessors, one or more microprocessors
in
conjunction with a DSP core, or any other such configuration.
In one or more exemplary embodiments, the functions described herein to be
performed by the energy harvesting manager and other devices used in the
invention
can be implemented in hardware, software, firmware, or any combination
thereof. For a
software implementation, the techniques described herein can be implemented
with
modules (e.g., procedures, functions, subprograms, programs, routines,
subroutines,
modules, software packages, classes, and so on) that perform the functions
described
herein. A module can be coupled to another module or a hardware circuit by
passing
and/or receiving information, data, arguments, parameters, or memory contents.
Information, arguments, parameters, data, or the like can be passed,
forwarded, or
transmitted using any suitable means including memory sharing, message
passing, token
passing, network transmission, and the like. The software codes can be stored
in
memory units and executed by processors. The memory unit can be implemented
within the processor or external to the processor, in which case it can be
communicatively coupled to the processor via various means as is known in the
art.
If implemented in software, the functions may be stored on or transmitted over
a
computer-readable medium as one or more instructions or code. Computer-
readable
media includes both tangible computer storage media and communication media
including any medium that facilitates transfer of a computer program from one
place to
another. A storage media may be any available tangible media that can be
accessed by
a computer. By way of example, and not limitation, such tangible computer-
readable
media can comprise RAM, ROM, flash memory, EEPROM, CD-ROM or other optical
disk storage, magnetic disk storage or other magnetic storage devices, or any
other
Date Recue/Date Received 2021-08-20
-29-
medium that can be used to carry or store desired program code in the form of
instructions or data structures and that can be accessed by a computer. Disk
and disc, as
used herein, includes CD, laser disc, optical disc, DVD, floppy disk and blu-
ray disc
where disks usually reproduce data magnetically, while discs reproduce data
optically
with lasers. Also, any connection is properly termed a computer-readable
medium. For
example, if the software is transmitted from a website, server, or other
remote source
using a coaxial cable, fiber optic cable, twisted pair, digital subscriber
line (DSL), or
wireless technologies such as infrared, radio, and microwave, then the coaxial
cable,
fiber optic cable, twisted pair, DSL, or wireless technologies such as
infrared, radio, and
microwave are included in the definition of medium. Combinations of the above
should
also be included within the scope of computer-readable media. Resources
described as
singular or integrated can in one embodiment be plural or distributed, and
resources
described as multiple or distributed can in embodiments be combined.
Thus, the present invention achieves one or more of the following advantages.
The
present invention provides a system which optimizes available energy sources
for use in
access control systems by monitoring available environmental and non-
environmental
energy sources using one or more energy source sensors to determine if energy
harvesting is possible and/or advisable. The system of the present invention
further
increases the efficiency of energy harvesting by optimizing available energy
sources.
The present invention further provides an improved method for managing
available
energy sources in an access control system and for managing power supply
circuits in
an access control system using harvested energy.
While the present invention has been particularly described, in conjunction
with
specific embodiments, it is evident that many alternatives, modifications and
variations
will be apparent to those skilled in the art in light of the foregoing
description. It is
therefore contemplated that the appended claims will embrace any such
alternatives,
Date Recue/Date Received 2021-08-20
-30-
modifications and variations as falling within the true scope and spirit of
the present
invention.
Thus, having described the invention, what is claimed is:
Date Recue/Date Received 2021-08-20
