Note: Descriptions are shown in the official language in which they were submitted.
CA 02543895 2006-04-18
STROBE LIGHT SYSTEM
FIELD OF THE INVENTION
The present invention relates a visual warning system and improvements
thereto.
BACKGROUND OF THE INVENTION
As is well known in the art, aeronautical communications frequently require
the use
of antenni which are mounted on top of a tower. Such towers can reach a
substantial height
- often extending up to 500 metres. These towers present a potential danger to
aircraft in
the area as they are not always readily visible, particularly under poor
weather conditions.
Accordingly, it is usually mandated by Governments that such a tower or any
other structure
shall be marked in accordance with certain standards.
A visual warning system is usually employed to warn pilots on a potential
collision
course with such a structure during the day or the night. Typically, flashing
high intensity
lights have been used with the intensity of the flash changing according to
the ambient
conditions. Thus, during daytime, a high intensity strobe light is usually
employed while
during night time, a much lower intensity light is utilized. A medium
intensity may be used
during the transition hours from light to dark and vice versa.
As is self evident, such light emitting warning systems do require maintenance
and
due to the critical nature of the system, such repairs must be effected
rapidly. This becomes
a relatively expensive operation as the towers are frequently in remote
locations and skilled
people must be called in to climb the tower, diagnose the problem, and make
repairs to the
system.
A typical system will include a strobe light, one or more capacitors to store
the charge
for the flash, a transformer, and associated electronic components mounted on
a circuit
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board. In order to effect the repairs, the technician must climb the tower,
diagnose the
problem, descend to the base to obtain the required components for repair, re-
climb the
tower, and install the new components.
Since there are different manufacturers of warning light systems, the people
effecting
the repair must carry a considerable number of replacement parts. This, in
practice, means
that a truck like vehicle must be employed.
As any owner of towers generally does not have enough towers in a single area
to
justify maintaining staff on hand for such repairs, it is frequently a third
party contractor
who makes the repairs. Again, distance to the location can become a problem.
One of the reasons for a relatively high rate of repair is the type of
structure employed
for the warning light assembly. As aforementioned, such assemblies typically
contain the
strobe lights, one or more capacitors, an electronic control system, etc. With
each flash,
ozone is created and as a result, corrosion of the various electronic
components becomes a
problem.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide improvements in warning
light
systems wherein the amount of maintenance on the system is reduced.
It is a further object of the present invention to provide an improved method
for the
installation of a visual light system on structures.
According to one aspect of the present invention, in a tower having a warning
light
system, the improvement comprising a light assembly mounted on the tower, the
light
assembly comprising a light emitting device and at least one capacitor for
supplying
electrical power to the light emitting device, and a control system mounted at
the bottom of
the tower, the control system comprising a switching power supply, and a
control circuit, the
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control circuit being effective to control the intensity of the light emitting
device and the
frequency of flashing of the light emitting device.
According to a further aspect of the present invention, there is provided a
method
for minimizing maintenance of a tower mounted strobe light warning system, the
method
including the steps of placing a light head assembly on the tower, the light
head assembly
having at least one flash head and at least one capacitor mounted therein, and
placing a
second station proximate a base of the tower, the second station including a
switching power
supply and a controller circuit.
In greater detail, these warning light systems are normally placed at
different levels of
the tower or other structure. When used in a tower, typically three light
heads are placed at
any level with each light having a visibility of at least 120°.
Depending upon the tower
height, one can have up to seven different levels of lighting.
As stated above, the present invention utilizes three different modules. For
mounting
on the tower, there is provided the light assembly which will include the
light emitting
device as well as one or more capacitors associated therewith. This is the
only portion
mounted on the tower and accordingly, the maintenance thereof is minimal since
the
capacitors have a long life as does the lighting device which is typically a
xenon tube. A
xenon tube will normally function for at least seven years before requiring
replacement.
Mounted at the base of the unit is an assembly which will include the power
switching supply as in one module and a controller module. Each controller
module will
preferably be adapted to control all the power supply units at any one level.
A single
controller can be utilized to control between three to ten light assemblies.
The controller has a primary function of controlling the synchronization of
the
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different lighting heads and to control the intensity of the lighting heads as
well as
coordinating the entire system.
Preferably, the intensity is determined by two photoelectric cells each of
which has a
predefined level such that one is suitable for night and the other for the
transition hours
between daylight and dark. Naturally, the intensity is at its maximum during
the day and at a
minimum at night. The intensity level is well defined in the standards of the
FAA.
Communication between the controller and the power supply units is established
by
an RS-485 network. A master/slave protocol is utilized. In normal operation,
the controller
is the master. If a problem arises in one of the power units or if the
controller is defective,
communication between the power units is still possible.
If a problem is detected by the controller, several actions can be taken.
First of all,
the malfunction is registered and then signalled by means of LED's or like
devices.
Depending upon the nature of the problem, one of the two alarm relays can also
be
activated. These alarms can be connected to suitable communication means
(modem,
cellular, etc.).
The controller module will preferably have display means which enable one to
quickly glance thereat to determine the functioning of the system. There may
also be
provided means such as push buttons which can be utilized to configure the
different
parameters.
The power unit is designed to feed power to the light head and to control the
flashing.
Again, suitable display means may be provided to indicate the status thereof.
The light assembly will include a suitable light emitting device and to this
end,
typically xenon tubes are lighted by the discharge of a capacitor. The
flashing frequency
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may vary and is typically between one and five seconds.
In a preferred embodiment, the controller and power supply are each
manufactured as
a module which is preferably of a plug-in type. In so doing, rather than
attempting repairs
on site, a module which is defective is removed and replaced by the
technician. The
defective modules can then be forwarded to a repair centre for repair.
BRIEF DESCRIPTION OF THE DRAWINGS
Having thus generally described the invention, reference will be made to the
accompanying drawings illustrating embodiments thereof, in which:
Figure 1 is a schematic diagram illustrating the overall arrangement of a
visual
warning system;
Figure 2 is a view of the interface with the controller;
Figure 3 is an illustration of the interface for the power unit;
Figure 4 is a schematic of the light head assembly;
Figure 5 is a schematic of a typical system;
Figure 6 is a schematic of a modular system for controlling a series of lights
on
different levels;
Figure 7 is a schematic of the controller; and
Figure 8 is a schematic of the power unit.
DETAILED DESCRIPTION OF THE INVENTION
Referring to the drawings in greater detail and by reference characters
thereto,
Figure 1 illustrates a base system wherein a controller 10 and power supplies
12 are placed
on the ground near the base of the tower while situated remotely therefrom are
the light head
assemblies 14.
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Figure 2 illustrates the interface with the controller. The controller has as
a principal
task the function of assuring the synchronization of the different light head
assemblies 14
and of controlling the intensity of the light and supervising the whole of the
system.
The intensity of the light is determined by two photoelectric cells which are
mounted
exteriorly. The photo cells are operative to control the lighting, one of the
cells being for
dusk and the other for night time. In full daylight, the intensity is at its
maximum while at
night, the lighting is generally at a minimum. At dusk, an intermediate
setting is utilized.
The communication link between the controller and the power units is done
using an
RS-485 network. The protocol is that of a master/slave which in normal times,
the
controller is master. However, if a problem occurs in one of the power units
or if the
controller is defective, the communication can continue between the power
units.
If a problem is detected by the controller, several actions are taken.
Firstly, the
problem is registered and a light is used to signal the problem. If necessary,
one of the two
alarm relays could be activated to send a report. This can be done by modem,
cellular, etc.
The interface of the controller with the user is accomplished by use of LED's.
The
settings of the controller can be modified through use of buttons 20, 22, 24
and 26. Thus,
buttons 20 and 22 which are arrow keys can be utilized to program the system
to the desired
parameter at which time the button 24 would be pressed to enter the setting or
button 26 to
cancel. Some of the parameters which can be programmed would be the flash
rate, the
number of levels, the number of flash heads, the time and the date, the light
intensity and
switching between automatic and manual mode. Thus, as shown in Figure 2, a
plurality of
LED's 16 may be utilized to indicate the proper functioning of the strobes at
the various
levels. The LED's 18 will indicate the flash intensity (daylight, night time
or dusk). The
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LED's 28 may be used to visual alarms while LED's 30 and 32 indicate the
status and
power on or off respectively. A display 34 may be provided in a conventional
manner.
Figure 3 illustrates the interface for the power unit. The different lights
indicate the
status of the unit and of the light head assembly it controls. As will be
noted, there can be a
high voltage alarm 35 which indicates that there is excessive voltage present
in the interior
of the unit or the interior of the light head assembly. Keys or buttons 36 and
38 may be
provided as was the case for the controller unit.
Figure 4 is a schematic of the light head assembly. Inside the light head
assembly are
the capacitors which control the intensity of the light. Thus, each capacitor
or bank of
capacitors is arranged to control a given light level as previously described.
As may be seen,
the light head assembly carries a minimum number of components and thus
maintenance
involving climbing the tower is minimized.
The power supply unit is preferably manufactured as a module and operates on a
plug-in basis. Thus, should any component become defective, the technician
merely needs
to remove the entire module and plug in a replacement module. The defective
module can
then be sent to a repair center.
Figure 6 illustrates an arrangement wherein the modular power supply units 12
may
be placed inside a rack which can contain six of the power supply units 12. As
may be
seen, there is provided a relay extending from one row of power supplies 12 to
other rows.
Figure 7 is a schematic of the controller and as may be noted, there are
provided a
pair of photocells. In the illustrated embodiment, there are provided three
lighting levels.
In Figure 8, there is illustrated a schematic for the power supply units. The
two high
tension outlets and photocells are an optional arrangement and can be included
to provide
CA 02543895 2006-04-18
redundance in the system.
It will be understood that the above described embodiments are for purposes of
illustration only and that changes and modifications may be made thereto
without departing
from the spirit and scope of the invention.
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