Note: Descriptions are shown in the official language in which they were submitted.
CA 02387540 2002-05-27
ELECTRONIC PARKING METER SYSTEM
BACKGROUND OF THE INVENTION:
1. Field of the invention:
The field of the present invention is parking meters and more
particularly to the use of electronically operated parking meters
coupled with a sensor for positively sensing unobtrusively the
presence or absence of a vehicle in a specified parking space
controlled by the sensor and electronically operated parking meter.
,In the present invention an induction coil mounted below the
surface of the parking area is used to provide positive signals to
the electronically operated parking meter and a cpu upon both the
entrance of a vehicle into the parking space and the movement of
the vehicle from the parking space.
4:
Moreover, the detecting system is battery operated and the
battery life is extended by duty cycle operation of the detector
system, whereby only a small portion of a detecting cycle is
actually employed for detecting the status of the parking
space.
2. Related Art:
Parking meters have traditionally been used to raise revenue.
Such devices have included a timer and a winding mechanism
requiring coins. More recently, electronic meters have been
developed which include an electronic timer with an LCD time
indicator.
With the advent of the electronic meter, attempts have been
made to make the meter interactive with vehicle traffic in the
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associated parking space. One way to obtain information about
vehicle traffic at parking spaces is to couple the parking meter to
a vehicle sensor. The vehicle sensor can detect when a vehicle
eriters a parking space as well as when the vehicle leaves. One
such system uses an infra-red light beam to detect vehicle presence
at a parking space.
Individual parking meter systems have each utilized different
vehicle sensors, such as an infra-red light beam, ultrasonic
systems and inductance type sensors to detect the presence or
absence of a vehicle in an associated parking space.
One problem with light beam detection is that the beam does
not distinguish between a vehicle and any other solid object. Thus,
the system could be disabled by simply covering the window from
which the light beam is emitted with a piece of tape or cardboard.
In addition, false activity could occur with thia opening of adoor
or other movement in front of the meter sensor. Even temperature
or humidity changes could cause problems. Consequently, interest
remains in developing an electronically controlled parking meter
system that overcomes the aforementioned problems and is capable of
accurately detecting vehicle traffic at a parking space.
There are a number of known parking meter vehicle detector
systems, namely:
(1) USP#3,873,964, VEHICLE DETECTION; Potter
The loop oscillator of the vehicle detector system
continually oscillates at the resonant frequency during normal
operation of the system and digital circuitry in the system
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measures the frequency of' the loop oscillator by a cycle-counting
technique. An automatic timing circuit generates a reference frame
time for the frequency counting measurement. The reference frame
tiine is a function of the desired operational sensitivity of the
system and of the resonant frequency of the loop and lead-in loop
oscillator frequency-determining circuit. A vehicle .is detected
whenever an increase of loop oscillator frequency counts occurs
from one reference frame time to the next, and when that increase
exceeds a predetermined threshold.
(2) USP#3,875,555; VEHICLE DETECTION SYSTEM; Potter; Indicator
Controls, Corp.
The magnetic inductance vehicle detection system includes
an embedded wire loop to sense the presence of a vehicle in a
roadway. A first oscillator connected to the loop changes
frequency as the loop inductance changes due to the presence of a
vehicle. A second oscillator with a frequency independent of the
loop inductance is used as a reference. Logic circuitry emits a
signal whenever the oscillator loop frequency exceeds a
predetermined frequency beyond a predetermined frequency
di2:ferential.
(3) USP#Re29511; PARKING METER; Rubenstein
The parking meter electrically indicates "remaining time"
and electrically operates only in the presence of a vehicle and
when there is "paid-for" time on the meter. Unused time by one
departing motorist is cancelled.
(4) USP#3 943 339; INDUCTIVE LOOP DETECTOR SYSTEM; Koerner et
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al.; Canoqa Controls Corporation
An oscillator circuit is operatively connected to each
one of multiple inductance loops each located in a given space in
a roadway and the loop frequency is monitored by a counter
measuring the time duration or period of loop oscillator cycles.
The monitored oscillator cycle is then compared with a reference
duration to determine whether the loop oscillator frequency has
increased or decreased.
(5) USP#3,989,932; INDUCTIVE LOOPVEHICLE DETECTOR; Koerner;
Canoga Controls Corporation
Oscillator circuitry is connected to an inductance loop
for detecting the presence of vehicles and the loop frequency is
monitored by a loop counter for counting the loop oscillator
cy-cles. A duration counter measures the time duration of a fixed
nu:mber of loop oscillator cycles and the count is compared with an
adaptable reference duration to determine an increase.,or decrease
in the loop inductance, thereby determining the presence or absence
of a vehicle in the inductance loop.
(6) USP#4,358,7491 OBJECT DETECTION; Clark; Redland Automation
Limited
An inductive sensing loop is connected. with an oscillator
provided with a voltage controlled capacitor in a phase locked loop
providing a reference frequency (VCO). The voltage of the
capacitor varies in the presence of a vehicle and this varying
vo:Ltage is applied to an auxiliary VCO whose frequency is
accordingly varied and analyzed for detection purposes. A
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microcomputer includes a clock source that is a reference frequency
source.
17 ) USP#4 , 472 , 706 ; VEIiICLE PRESENCE LOOP DETECTOR; Hodcre et
alõ; Not Assigned
A tuned circuit having a magnetic field-producing
induction loop produces changing signals in the presence of a
vehicle. A first signal amplifier amplifies the signal from the
loop and a second amplifier responds to the positive or negative
polarity input from the first amplifier to provide an output in
response to a rapidly changing input which activates a logic gate
for sensing the polarity of the second amplifier output and
producing a gated output signal indicative of the presence or
absence of a vehicle within the loop.
(8) USP#4,491,841; SELF-ADJUSTING INDUCTIVE OBJECT-PRESENCE
DETECTOR; Clark; Sarasota Automation Limited
An oscillator includes an inductive sensing loop and a
first counter samples the oscillator frequency or period and the
resulting count is applied as a preset reference to a second
counter which is counted down in one sample period while a new
count is counted by the first counter. The residue in the second
counter at the end of a sample period is indicative of the presence
or absence of a vehicle. Provision is made for detection of the
departure of a vehicle by use of additional counters.
(9) USP#4,680,717; MICROPROCESSOR CONTROLLED LOOP DETECTOR
SYSTEM; Martin; Indicator Controls Corporation
A microprocessor-controlled loop detection system is
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. ~ ~
connected to a number of inductive loops which are individually
located to detect the presence of motor vehicles above the loops to
control motor vehicles at a traffic intersection. A common
oscillator is connected to each loop on a time shared basis and the
microprocessor counts the number of cycles of the oscillator output
signal to determine the oscillator frequency.
(10) USP#5,153,525; VEHICLE DETECTOR WITH SERIES RESONANT
OSCILLATOR DRIVE; Hoeckman et al.
The series resonant oscillator circuit drives an
inductive load including an inductive sensor and a detection system
using the series resonant oscillator circuit and inductive sensor.
An inductive load is connected in the seriLes path with a
capacitative impedance. An oscillator signal provides power to the
se:ries path and is controlled as a function of current sensed in
the series path. The frequency of the oscillator signal changes as
a function of changes in the inductance of the inductive sensor.
(11) USP#5.570.771; ELECTRONIC PARKING METER AND SYSTEM;
Jacobs
The parking meter system uses a low-current drain
electronic parking meter and a mobile transceiver. A sonar
transducer detects the presence of a vehicle in an adjacent parking
space and an infra red transceiver communicates with the mobile
transceiver. A microprocessor responds to electrical signals from
the various detectors to provide data displayable on a display and
transmittable by the IR transceiver to the mobile transceiver. The
meter is entirely battery operated and can operate for an extended
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period of time, for example, six months to one year, without
battery replacement.
(12) USP#5.903.520; ELECTRONIC MODULE FOR CONVENTIONAL PARKING
METER; Dee et al.
The electronic module comprises a shell attachable to a
conventional parking meter and a meter condition sensor for
detecting, from a distant point, time and violative conditions of
the parking meter with the indicator in an indicating mode, and an
ultrasonic vehicle sensor aff"ixed to the shell for detecting a
parked vehicle. The electronic module fur-ther includes electronic
circuitry with a power source for operating the module; means for
receiving a first signal from the meter condition sensor and a
second signal from the vehicle sensor; means for processing the
first and second signals and means for transmitting a coded message
to a remote receiver.
(13) USP#5.936,551 L VEHICLE DETECTOR WITH IMPROVED REFERENCE
TRACKING; Allen & Potter
A vehicle detector having improved reference tracking
routines in both the NO CALL and CALL directions and wherein CALL
direction tracking includes rate sensitive tracking wherein the
reference is only changed in response to small fluctuations in loop
frequency due to drift, and one or more fixed decrementing tracking
in'tervals during which the reference is decremented at a fixed rate
for a maximum predetermined period of timeõ CALL direction
tracking also included infinite tracking during which the reference
is decremented to an end value representative of loop inductance
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prior to the end value representative of loop inductance prior to
the generation of a CALL signal. No CALL tracking enables
reference updating only after the loop frequency has stabilized for
a minimum period of time, a minimum number of loop frequency
samples or both.
SUMMARY OF THE INVENTION
The present invention is directed to an electronically
controlled parking meter system which employs an electronically
operable parking meter in combination with an inductive loop coil
used for vehicle detection. Over the past forty years inductive
loops have been used for many types of systems requiring vehicle
detection. Such systems include traffic control signal systems,
automatic gates, drive thru restaurants, etc. Inductive loops,
when properly installed, have proven to be very reliable for the
purpose of vehicle detection.
In a first, separate aspect of the invention, an
electronically operable parking meter may be coupled to an
induction coil vehicle detection sensor located or embedded in the
surface of the parking space for selectively controlling the
electronically operable parking meter responsive to the inductive
loop sensor. A vehicle entering or leaving the parking space
causes a change in the apparent inductance of the inductive loop
and the resulting signal output from the sensor may be used to
control the electronically controlled parking meter and associated
control circuitry. The electronically operable parking meter
system may be used to initialize or reset the parking meter when
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the inductive loop sensor indicates the entry or departure of a
vehicle from the associated parking space. The electronically
operable parking meter system may also be used to accumulate data
associated with the activity of the particular parking space; such
as number of vehicles using the space, duration of elapsed time for
eah or all vehicles using the space, etc.
In a second, separate aspect of the present invention,
multiple electronically operable parking meters may be coupled to
a single power supply. Each electronically operable parking meter
ti
may be coupled to a separate inductive loop vehicle sensor for
selectively controlling the parking meter responsive to its sensor,
as in the electronically operable parking meter of the first,
separate aspect.
In a third, separate aspect of the present invention, the
electronically operable parking meter of the second, separate
aspect may include a remote data processing unit (DPU). The remote
DPU may be coupled to each electronically operable parking meter.
The remote data processing unit may be utilized for gathering data
in order to obtain statistics on vehicle traffic, traffic patterns,
and other information, which could be utilized for establishing
more efficient use of parking spaces. This system would be
deployed for monitoring and/or controlling a large number of
parking spaces; for example, a parking garage, or the length of an
entire street, etc.
A fourth aspect of the present invention is that the parking
meters are electrically operated as opposed to mechanical operation
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of known parking meters.
A fifth aspect of the present invention relates to the use of
solar energy for providing the electric power to operate the
electronically operable parking meter system, and in particular the
electronically operable parking meter(s) and the associated
electronics. This involves at least the consideration of using
solar panels in ambient sunlight as well as direct sunlight since
the electronically operable parking meter system may be utilized in
locations where direct sunlight is not available or only
intermittently available.
A sixth aspect of the present invention relates to the
modification of existing parking meters, and particularly
mechanically operable parking meters, to enable them to function in
the electronically operable parking meter system of the present
invention.
A seventh aspect of the present invention concerns the
economical optimization of electronically operable parking meter
systems by controlling the electronically operable parking meter so
that the meter is "zeroed" when the inductive loop sensor
associated with the meter detects that a vehicle has vacated the
parking space controlled by the inductive loop.
Accordingly, it is an object of the present invention to
provide an electronically operable parking meter system which is
capable of detecting the vehicle traffic at particular parking
spaces.
More particularly, it is an object of the present invention to
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provide positive and accurate sensing of the presence or absence of
a vehicle in a particular parking space within a given vehicle
parking area. It is a feature that the sensors employed by the
electronically operable parking meter system of the present
invention are inductive loop sensors embedded in the surface of a
parking space.
It is an advantage of the present invention that the inductive
loop sensor is unobtrusive and not hindered by the presence of
surface objects in the vicinity of the parking space.
It is yet another object of the present invention to connect
a plurality of electronically operated parking meters to a single
electrical power source, which may include electric batteries,
mains power and/or solar powered electrical energy.
It is yet another feature that rechargeable batteries in
conjunction with solar power energy may be used to provide
emergency electrical power for the electronically controlled
parking meter system of the present invention in the event of
failure of a main power supply.
It is yet another advantage of the electronically controlled
parking meter system of the present invention that the electrical
power for operating the electronically operable parking meters,
inductive loop sensors, and the DPU is automatically rechargeable.
Still another object of the present invention is to enable
existing parking meters to be modified to operate electronically.
Still another feature of the present invention is to provide
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electrical circuits and connections to existing mechanically
operated meters to enable them to operate electronically.
Still another advantage of the present invention is that the
cost of a parking meter system may be reduced by modifying existing
mechanical type parking meters to operate electrically.
Yet another object of the present invention is to increase the
the economical operation of electronically operable parking meter
systems.
Yet another advantage of the electronically operable parking
meter system of the present invention is that the parking time
purchased for a specific vehicle can only be used by that vehicle.
When any vehicle vacates the parking space the remaining time is
lost; and the next arriving vehicle must purchase new time for t.k}e
use of the parking space.
Yet another advantage of the electronically operable parking
meter system of the present invention is that a limited amount of
parking time may be provided, possibly at no cost, for arriving
vehicles. Further, the vehicle would not be able to purchase
additional time for the space. This operation of the tl
electronically operable parking meter system would control the
allowed time of use for each vehicle. Limited parking time is
common practice near Post Offices, banks, etc.
The vehicle detection system/parking meter system produces a
variety of value-added parking meter capabilities. The vehicle
detector system utilizes ultra low power "wire loop detection"
technology and a programmable microprocessor to interface with a
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digital or electronic parking meter. The vehicle detector reliably
detects the arrival and departure of automobiles and motorcycles
from a given parking space and sends the appropriate
arrival/departure signal to the digital meter. This signal then
enables the parking meter to accomplish any number or pre-
programmed functions.
The value added functionality includes:
(1) Reset the digital parking meter to zero when the parking
space is vacated, thus significantly increasing meter revenue in
high demand situations. Independent research reveals that average
revenue increase approximately 27% in high demand parking locations
when using this technique.
(2) Prevent "meter feeding" by not posting additional time for
over-limit payments until after the parking space has been vacated,
thus forcing parking space turnover and, in effect, increasing
overall parking capacity.
(3) Automatically allocate free time as the parking space is
occupied. This will enable very short term parking spaces in front
of commercial establishments like dry cleaners and convenience
stores to be more effectively managed.
(4) Track all parking space related events, making it possible
to analyze this data to determine how to most cost effectively
deploy parking resources.
For many years the ubiquitous mechanically operated parking
meter has toiled in anonymity, quietly taking quarters and
dispensing 10-30 minutes of parking privileges. This "ironclad"
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version of the mechanical kitchen timer has been the standard for
parking control in cities across the nation for decades.
However, several years ago, the old mechanical meter began to
be replaced by a newer, more modern alternative, namely the new
electronic or digital meter that utilizes an LCD read out and far
fewer moving parts. It was the first real improvement in parking
meters in many years. The meter offered the municipalities
utilizing it few additional benefits other than fewer parts to
break or replace.
However, with the present invention there is a parking system
which redefines the way parking authorities monitor, track and
enforce metered parking spaces in their cities or municipalities.
This system enables a digital parking meter to become a data
collection device that can both control and monitor a range of
activities in a given parking space.
While raising parking rates is an unpopular step as
perceived by municipal managers, the technology of the present
invention can increase parking revenues without raising parking
rates. Additionally, with the ability to collect and analyze
parking space occupancy and turnover data, the present invention
provides a parking authority with the information to enable it to
save money, by making more efficient use of all of the parking
resources.
The present invention utilizes a programmable microprocessor
that links the digital parking meter directly to the parking space
by utilizing loop detection technology. Traffic engineers have
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used traditional high voltage loop detection technology to manage
traffic signals for years. wires embedded in the pavement at
intersections sense when a vehicle is stopped at a signal and
changes the light. The vehicle detection system of the present
invention works substantially the same way only with an ultra low
power detection system. A wire is run from the parking meter, down
the inside of the meter pole and is embedded in the pavement in the
form of a coil. The coil is installed in the parking space
associated with the parking meter. When a vehicle enters the
parking space, the meter is signaled by the vehicle detection
system, the event is time-stamped, and whatever meter functions
have been preprogrammed are initiated. The process is repeated
when the vehicle leaves the parking space as the vehicle detectQr
system notifies the digital meter of that event.
One principal feature of the invention is the "time sweep"
function. When a customer leaves the parking space and there is
still time remaining on the parking meter, the vehicle detection
system resets the timer to zero. In high demand situations, this
feature will enable the parking authority to generate significantly
greater revenue. Independent research confirms that the benefit of
this feature is an improvement in revenue of 10 to 40% and 'an
average of 27% in high demand spaces. With the present invention,
meter revenue that was previously limited to a fixed number of
coins per day can now become variable based upon usage. Since many
municipalities rely heavily on parking meter revenue to fund their
operating budgets, it has been discovered that the potential of
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being able to generate a significant increase in revenues, without
raising the price of parking, is a key selling point for the
present invention.
On a"stand-alone" basis, the electronic single-space parking
meter has a flexibility that has previously not been available to
the parking authority. The electronic parking meter now knows
where it is, who it is, the time of day, the day of the week and
the day of the year.
All of these features combine to allow a wider range of
benefits to the parking system operator. By virtue of flexible
internal programming the electronic parking meter can:
(1) Change rate structures several times a day;
(2) Put itself to "sleep" during specified periods;
(3) Recognize that it is out of order and display that
information;
(4) More accurately discriminate valid from invalid payment
tokens (coins, etc.);
(5) Accept electronic payment in lieu of cash.
The present invention expands these features by providing
information about the real time occupancy of the parking space that
is controlled by its associated electronic meter. When the vehicle
detector system of the present invention is connected to the
electronic meter described above, the electronic meter may be
programmed to add "free" time to the parking clock when a vehicle
arrives in a parking space, and remove remaining time when the
vehicle leaves. The electronic meter can also be programmed to
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disregard any coins deposited after a full time limits worth of
time has been purchased by the current occupant (also known as
Meter-feeding), and resetting itself to function normally after the
current occupant departs the space.
The newest electronic meters are capable of storing a vast
number of incident records in NOVRAM (non-volatile random access
memory) to be later retrieved and analyzed in addition to the
features listed for the older model, above. These incident records
reveal the exact date and time of any pre-programmed transaction.
For example, a transaction record can be stored every time a
payment token is inserted into the meter. If the token is deemed
valid, the value is displayed on the parking clock and that
transaction is stored. If the coin is judged invalid, tY~e
;.
transaction record shows that fact and no time is added to the
{
parking clock. A record can be stored should the electronic meter
become dysfunctional, showing that exact time and date. When the
electronic meter is restored to operability, a record is stored
noting that event.
With the addition of the vehicle detector system of the
present invention to the new electronic parking meter as briefly
described above, a transaction record can be stored showing the
exact date and time of the arrival of a vehicle and the exact date
and time of departure. This data, when combined with the other
records being stored, can provide a wide variety of real-time
management information to the parking manager. Among other facts,
when the vehicle detection system of the present invention is
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employed, the analysis can show:
(1) Daily occupancy;
(2) Daily Space Turnover;
(3) Over-limit stays and amount of time in violation:
(4) Length of stay for each occupant;
(5) Duration of vacant time; and
(6) Time-span of highest usage.
When the above data are combined with data collected by
an electronic citation issuance system, the parking manager can
learn which enforcement tactics work best in subsections of the on-
street parking system. The deployment of repair and enforcement
personnel can be managed based on legit~mate data retrieved from
discrete areas within the system, thereby saving many labor hours
of unproductive time.
i
Thus a first object of the present invention is directed to an
electronically controlled parking meter system which employs an
electronically operable parking meter in combination with a low
power, battery-operated vehicle detection system employing an
induction coil.
Therefore in a first feature of the invention, an
electronically operable parking meter is coupled to a detector for
detecting the status of an induction coil vehicle detection sensor
located or embedded in the surface of the associated parking space
for selectively controlling the electronically operable parking
meter. A vehicle entering or leaving the parking space causes a
change in the apparent inductance in the induction coil and the
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resulting signal output is used to control the electronically
controlled parking meter and associated control circuitry. The
electronically operable detector parking meter system of the
invention is used to re-initialize the electronic parking meter
when the induction coil sensor indicates the entry or departure of
a vehicle from the associated parking space.
Each electronic parking meter includes a preformed induction
coil comprising several turns of wire and a specified perimeter.
The wire leads from the coil to the detector electronics are
twisted to form a single pair conductor. This pre-formed loop
construction is advantageous as it simplifies installation and also
insures that the detector loop is correct when installed. In a
preferred embodiment of the invention, the coils each comprise four
turns of wire and have an approximate perimeter of ten feet.
A second object of the present invention is to provide a
parking meter detection system wherein each of the detectors and
electronically operable parking meters are operated by separate,
independently operable battery power supplies.
The detector of the invention utilizes a duty cycle ON/OFF
technique to preserve battery power and wherein the detector
operates at a preferred frequency of 80 KHz and is ON for
approximately 12.5 ms and is OFF for 2.5 sec. minus 12.5 ms. Thus,
the detector is ON for approximately only 0.5% of the duty cycle of
the detector. This conserves the battery power of the detector so
that it may actually last longer than the other battery in the
electronic parking meter.
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A third, object of the present invention is to include a
microprocessor in the detector for providing serial control and
information data to the electronically operable parking meter.
A fourth object of the present invention is that both the
detector and the associated parking meter are electronically
operated.
A fifth object of the present invention concerns the
economical optimization of parking meter systems by controlling the
electronically operable parking meters so that the meter is
"zeroed" when the induction coil sensor associated with the meter
detects that a vehicle has vacated the parking space controlled by
the induction coil.
Other and further advantages will appear hereinafter.
BRIEF DESCRIPTION OF THE DRAWINGS:
Figure 1 is a perspective view of an inductive loop-
controlled, dual, electronically operable parking meter in
accordance with the invention;
Figure 2 is a front view of a solar energy powered inductive
loop-controlled, dual, electronically operable parking meter in
accordance with the invention, wherein the meter stand and the
ground are cut-away for clarity;
Figure 3A is a schematic diagram of the wiring system of an
inductive loop-controlled, electronically operable parking meter
system in accordance with the invention wherein solar power is
employed; Figure 3B illustrates an embodiment of the invention
wherein the solar panels are mounted on the electronic controller
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housing, which in turn is mounted on a narrow parking meter stand
between dual electronically operable parking meters; and Figure 3C
illustrates the solar panels mounted on top of a large parking
meter stand with the electronic controller housed therein;
Figure 4 is a cut-away view of an electronically operable
parking meter illustrating the circuitry and wiring modifications
necessary to couple the meter to the meter stand;
Figure 5 is a flow diagram showing the communication between
tan electronicalfy operable parking meter and a DPU in accordance
with the invention;
Figure 6 is an overview of multiple dual electronically
operable parking meters connected to an existing traffic signal
power supply via power lines in accordance with the invention;
..Ir
Figure 7 is a block diagram representation of the vehicle
~
detector system and the electronic parking meter of the invention;
Figure 8 is a circuit schematic of the detector system of the
present invention;
Figure 9 illustrates the ON/OFF cycle of operation of the
detector circuit of Figure 7; and
Figure 10 shows the relationship of the detector loop
oscillation cycles to the crystal oscillation cycles of the
microprocessor controller in the loop detector circuit.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT:
Turning in detail to the drawings, Figure 1 illustrates an
inductive loop-controlled, electronically operable parking meter
system in accordance with the invention. The curbside parking
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meter stand 2 supports two electronically operable parking meters
4 and 6. The two inductive loops 8 and 10 are embedded in the
pavement in the parking spaces corresponding to the parking meters.
The right and left induction loops 8 and 10 are connected to the
right and left electronically operable parking meters 4 and 6,
respectively.
Inductive coils 8 and 10 each comprise several turns of
insulated wire and are each wound to a specific size perimeter.
The loops may be shaped as round, square, octagonal, etc. Further
the inductive loops may be preformed prior to installation, or
they may be wound with a single conductor wire using the saw cut in
the pavement as the form. Leads 11 and 12 from the loops 8 and 10
are twisted together to form single pairs of conductors. The
twisted pair 11 from loop 8 connects to the electronic circuitry of
parking meter 4 and the twisted pair 12 from 10 connects to the
parking meter 6. Parking meters 4 and 6 each provide electrical
currents to the loops 8 and 10, thus crating independent electrical
fields in the proximity of the two inductive loops. Whenever a
vehicle enters the electrical field created by loop 8 a disturbance
to that field occurs and the electronic circuitry in parking meter
4 establishes the presence of a vehicle in the zone assigned to
parking meter 4. Whenever a vehicle enters the electrical field
created by loop 10 a disturbance to that field occurs and the
electronic circuitry in parking meter 6 establishes the presence of
a vehicle in the zone assigned to parking meter 6.
The system may use a solar energy power supply. Systems
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using a solar power supply may have a solar panel located either at
or apart from the electronically operable parking meter stand 2.
Figure 1 illustrates an electronically operable parking meter
system using solar power with a solar panel 12 located apart from
the parking meter stand 2.
Figure 2 illustrates a cut-away view of an inductive loop
controlled electronically operable parking meter system. The
hollow parking meter stand 2 contains a controller 14, a 12 volt dc
\ battery 16, a solar power regulator 18, a section of conduit 20 and
a steel cover 22. Brackets (not shown) support the electronic
controller 14, the 12-volt battery 16 and the solar power regulator
18, which are connected to the steel cover. Preferably, the
electronic controller 14 comprises a printed circuit board aqd
electronic components.
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The solar panel 12 is electronically connected to the solar
battery regulator 18. The solar battery regulator 18 is
electronically connected to the 12 vdc battery 16. Similarly the
12 vdc battery 16 is electronically connected to the electronic
controller 14. The section of conduit 20 extends from the bottom
of the parking meter stand 2, through a concrete block footing 24,
into the ground near the base of the parking meter stand 2.
A solar panel 12 is located on a support post 26 apart from
the parking meter stand 2. The solar panel 12 is electronically
connected to a junction box 28 located at the base of the support
post 26. The junction box 28 may be located below ground.
Insulated electrical wires 29 connect from the junction box,
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through the section of conduit 20, to the solar power regulator 18
located within the parking meter stand. Communication wires 31
lead from the junction box 28, through the section of conduit 20,
to the electronic controller 14 located within the parking meter
stand 2.
The wire which forms the coils 8, 10, described above, extend
back to the electronic controllers 14 within the parking meters 4
and 6 mounted on stand 2 via the section of conduit 20.
The inductive loops 8 and 10 are composed of, for example,
number 16 AWG stranded copper wire covered with insulation suited
for direct burial in the pavement. The wire leads feeding to and
from the inductive loops 8 and 10 are twisted together in a helical
configuration to minimize and control the electrical field emitted
from the pair.
There may be one or more parking meters attached to the
parking meter stand 2. A metal pipe 30extends horizontally from
a side of the parking meter stand 2 and curves vertically upward.
The electronically operable parking meter 4 or 6 may be mounted at
the end of the vertical segment of the metal pipe 30. Figure 2
shows the preferred configuration of two parking meters 4 and 6
attached to the meter stand 2 in the manner described.
It should be evident from the foregoing description that the
parking meters used with the present invention are electrically, as
opposed to mechanically, activated either by solar energy, battery
power or ac power from a mains supply, or a combination of all
three types of electrical power. The electrical operation of the
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parking meters of the present invention represents a significant
departure from the prior use of mechanically operated parking
meters. The features and advantages of electrically operated
parking meters will become more evident from the following
description of the electronically operable parking meter system of
the invention.
Figure 3A is a schematic diagram of the wiring system of the
induction loop controlled electronically operated parking meter
system. Inductive loop 8 connects to the electronic controller 14
within the parking meter stand 2 to terminals 100B of a terminal
strip 32. A separate inductive loop 10 connects to the electronic
controller 14 within the parking meter stand 2 to terminals 102B of
the terminal strip 32. Inductive loops 8 and 10 form two separate
inductive sensor loops, as described above, for use with two
electronically controlled parking meters. This is an example of a
dual electronically controlled parking meter system.
After forming the respective coils, the conductors 8 and 10
travel back to the terminal strip 32, where they are connected
through to the electronic controller 14. Figure 3B shows two such
configurations, as would exist in the case of a dual electronically
controlled parking meter.
The following is an explanation of the operation of the
electronic controller 14 under various conditions of time displayed
on the meter and the presence or absence of a vehicle in the
controlled parking space. (1) When there is no time displayed on
the electronically operable parking meter, power consumption is
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minimized by de-energizing the inductor loop sensor channels. (2)
With no time displayed on the electronically operable parking
meter, a vehicle entering or leaving the inductor sensor loop does
not effect the sensor electronics nor cause any reset pulse to
appear. (3) When time is displayed, the corresponding channel is
energized and initiated to produce a resetting pulse for any
vehicle leaving the inductor loop; and at that time the
!electronically operable meter is set to display "zero" time. (4)
When no time is displayed, the flasher output is activated when the
presence of a vehicle is indicated in the controlled space. (5)
When a vehicle is present and there is time displayed, the
electronic controller provides no signal output.
The electronically operable parking meter system may use a
solar power energy supply. In the preferred system, the external
solar panel 12 is electronically connected to a solar battery
regulator 18. Similarly, the battery regulator 18 is
electronically connected to the 12 vdc battery 16. The 12 vdc
battery 16 is electrically connected to the terminal strip 32, and
the terminal strip is electrically connected to the electronic
controller 14.
The solar panel 12 may be mounted a distance from the
electronically operable parking meters 4 and 6 as illustrated in
Figures 1A and 2, or the solar panel 12 may be mounted between -
electronically operable parking meters 4 and 6 as schematically
indicated in Figure 3A. Figures 3B and 3C each show an array of
12 inch solar panels 12' and 12" mounted between the electronically
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operable parking meters 4 and 6 and wherein the electronic
controller 14 is mounted on a 2 foot high parking meter stand 2'
and supports the solar panel array 12' as shown in Figure 3B, or as
shown in Figure 3C, the solar panel array 12" is mounted directly
on top of the parking meter stand 2" with the electronic controller
14 mounted within the parking meter stand 2".
The placement of the solar panel array 12 as shown in Figs 1A
~and 2 is best where there may be insufficient direct sunlight to
activate the solar array, such as for example where the parking
meter system is located on an urban street shielded by tall
buildings. However, where the electronically operable parking
meters are located where there is sufficient direct sunlight, such
as for example in open parking spaces, then the solar panel aiarays
may preferably be mounted to the parking meter stand as illustrated
in Figures 3B and 3C.
Each electronically operable parking meter 4 and 6 is
electronically connected to the electronic controller 14 that is
located within the parking meter stand 2. Figure 4 illustrates the
wiring necessary to connect the printed circuit board 34 in an
existing meter to the electronic controller 14. There are three
wires which connect the electronic controller 14 to the printed
circuit board 34 via the terminal strip 32. One wire 36 serves as
ground, another wire 38 controls the reset switch (not shown), and
the other wire 40 relates to vehicle detection. All three wires
36, 38 and 40 enter the electronically operable meter 4 or 6
through an opening 42 in the meter battery compartment 43.
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The electronically operable parking meter system may contain
a printed circuit board and a cpu within the controller 14 located
in the parking meter stand 2. The cpu may be used to monitor
and/or control operation of the electronically operable parking
meter system of the invention. Figure 5 is a flow diagram which
illustrates communications between an electronically operable
parking meter 4 or 6 and its cpu.
When a vehicle enters a parking space the electronically
operable parking meter 4 or 6 detects its presence. The
electronically operable parking' meter then begins timing and
notifies the cpu of the vehicle's presence. If coins are not
deposited into the meter within a predetermined period of tiMe
(perhaps 30-60 seconds), the electronically operable parking meter
flashes "zero" on its LCD and alerts the cpu as to the vehicle's
presence as well as the time at which the vehicle entered the
parking space. When coins are deposited into the electronically
operable parking meter, the parking meter performs three functions:
(1) it will count the coins, and notify the cpu that coins have
been deposited; (2) it will turn off the flashing "zero" on the
LCD; and (3) it will continuously measure and display the amount of
time remaining on the meter. If there has been delay (more than
30-60 seconds) in depositing coins, the meter will alert the cpu as
to the delay.
When a vehicle leaves the parking space while time remains on
the meter, the meter may wipe off any remaining time and notify the
cpu that the parking space is empty. When a vehicle remains in the
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parking space after the time has expired, the meter may flash
"zero" in its LCD and alert the cpu that a vehicle has remained in
the parking space after time has expired.
Multiple induction loop-controlled electronically operable
parking meters may have a single power supply. As stated
previously, the power supply may be solar energy, where a single
solar panel is used to supply energy to multiple meters.
``Preferably, the solar panel may be attached to an existing
structure, such as a street lamp, pole or a traffic signal support
post. Alternatively, multiple parking meters could receive their
power from a nearby traffic signal power supply.
Figure 6 illustrates power lines 46 running from an existiYlg
traffic signal power supply 48 to multiple dual electronic opetable
parking meter systems.
Multiple electronically operable parking meters may be
connected to a single cpu which receives information regarding
revenue collection at each meter and vehicle traffic at each
parking space. The cpu may relay information relating to vehicle
traffic and revenue collection to an information gathering and/or
processing center. Communications between the cpu and the
information processing center may be by a number of means,
including wire, fiber optics and radio waves.
In Figure 7 inductance loop 10, comprising 4 to 5 loops of
conductor, is connected by a twisted conductor pair 12, 14 to a
loop oscillator 16, which in the preferred embodiment of the
invention oscillates at 80 KHz. The function of the loop
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oscillator 16 is to detect the presence or absence of a vehicle in
the associated parking space (not shown), in which the inductance
loop 10 is buried below the surface, by detectingg a change in he
inductance of the inductance loop. The presence of a vehicle
causes an effective decrease in the inductance and the absence of
a vehicle results in an effective increase in the inductance of the
inductance loop 10. The effective change in the inductance of the
'inductance loop 10 causes a commensurate change in the oscillating
frequency of the loop oscillator 16, with decreasing inductance
causing an increase in the frequency and an increasing inductance
causing a decrease in the oscillating frequency of the loop
oscillator. By effectively sensing the change in frequency caused by,the
aforementioned change in inductance, which in turn represents the
presence or absence of a vehicle in the associated parking place,
the loop oscillator 16 positively identifies the presence or
absence of a vehicle in the parking space. The loop oscillator 16
provides signals to the microprocessor controller 18 that enables
it to positively determine the presence or absence of a vehicle in
the associated parking space. The microprocessor controller 18
generates serial data which is input to the electronic parking
meter 22 through output interface 20 to enable the electronic
parking meter to operate in a desired manner (to be more fully
described hereinafter). The electronic parking meter 22 is capable
of accepting coins enabling time to be purchased in accordance with
the amount of money deposited in the parking meter (as symbolically
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illustrated in Figure 6 by the "coin drop") in accordance with
accepted procedures for the same. Finally, the time purchased by
the coin drop in electronic parking meter 22 is displayed by time
display 24.
As illustrated in Figure 8, inductance loop 10 is connected to
oscillator circuit 26 through an isolation transformer 28, which
includes a capacitor 30 for suppression of transients, and a tuning
6pacitor 32 connected in parallel with the secondary of isolation
transformer 28 and oscillator circuit 26.
Oscillator circuit 26 is designed to oscillate at a base
frequency of 80 KHz, but has a variable rate of oscillation about
the base frequency in accordance with the presence or absence of=h
vehicle in the associated parking space. The oscillatory output of
oscillator circuit 26 is squared by squaring circuit 34 to enable
the oscillating signal to be accepted by microprocessor controller
18. Microprocessor controller 18 includes a 4 MHz crystal
oscillator 36 which provides the base operating frequency of the
microprocessor controller as shown in Figure 10.
It is a significant feature of the invention that the
electronically operated parking meter 22 and the oscillator circuit
26 are operated by independent dry cell batteries.
Microprocessor controller 18 provides an ON/OFF duty cycle of
operation of the detector system 16 as illustrated in Figure 9 in -
which the detector system 16 is activated for approximately 12.5 ms
and inactive ("sleep time") for 2.5 seconds minus the 12.5 ms
operating time of the detector system. This is an important
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feature of the invention, as it significantly reduces the battery
power required for operating the detector system of the invention.
This enables the battery operable up to nine to twelve months,
which considerably reduces the maintenance required of the detector
system.
LED indicator 38 provides an indication of the operation of
the microprocessor controller 18 and reset switch 40 enables the
controller to be reset as desired.
The detection of the presence or absence of a vehicle in the
associated parking space is as follows. The presence or absence of
a vehicle in the associated parking space respectively decreases or
increases the inductance of the associated loop 10 , which in turn
causes a respective increase or decrease in the frequenc)~ of
operation of the oscillator circuit 26.. The 4 MHz frequency
signals from the microprocessor controller 18 are superimposed with
the frequency of the oscillator circuit 26 as illustrated in Figure
9. Thus a decreasing frequency of the oscillator circuit 26,
resulting in a longer period of oscillation, will produce more 4
MHz signals in a given period of oscillation of the oscillator
circuit 26 than in the normal 80 KHz operation of the oscillator
circuit, thereby enabling the microprocessor controller to
determine the absence of a vehicle in the associated parking space.
Similarly for an increase in the frequency of the oscillator
circuit 26, associated with the presence of a vehicle in the
associated parking space, there is less of a period of oscillation
of the oscillator circuit 26 and a commensurate decrease in the
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number of 4 MHz signals to be counted by the microprocessor circuit
18.
The microprocessor circuit 18 also provides serial data output
to the electronic parking meter 22 to enable it to function in a
desired manner (to be described more fully hereinafter).
Therefore, it is desired that the present invention not
be limited to the embodiments specifically described, but that it
include any and all such modifications and variations that would be
obvious to those skilled in this art. It is my intention that the
scope of the present invention should be determined by any and all
such equivalents of the various terms and structure as recited in
the following annexed claims.
:=:
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