Swimming pool safety alarm

An infrared light emitter forms a beam of infrared (IR) light directed onto a set of mirrors or reflecting surfaces arranged to form a closed path about a swimming pool and spaced above the pool deck a sufficient amount so as to be intercepted by anyone who might walk through it. After the reflected beam has traversed the closed path about the pool, it then impinges upon a light detector. An electric circuit provides a continuous alarm which can either be sound or visual upon beam interruption and which must be manually reset before it becomes inactive. The monitoring system may be actuated so the operative state by a handheld radio frequency transmitter. Electrical power for the system can be a rechargeable battery which is recharged by a solar array mounted directly onto a part of the system obviating the need for interconnecting cable wiring.

The present invention relates generally to a safety alarm system for a 
swimming pool, and, more particularly, to such an alarm system giving an 
identifiable signal when an individual (e.g., young child) either falls 
into the pool or is closely adjacent the edge of the pool and in danger of 
falling into the pool 
BACKGROUND OF THE INVENTION 
Despite local ordinances requiring fencing and locked gates for swimming 
pools and the immediately adjacent areas, there are an alarmingly high 
number of deaths and brain damage occurring to young children who fall 
into the pools when no one is around to assist them. Young children are 
irresistibly attracted to a swimming pool and are known to climb over 
fences and to otherwise make their way to the pool and adjacent area so 
that there is a continuing possibility of danger to children in the 
neighborhood of a pool owner 
One known system for detecting an intruder (e.g., child) in the area of a 
swimming pool utilizes a passive infrared system which detects infrared 
energy emitted from the human body anywhere within a certain predetermined 
detection range and responsive to such detection transmits a radio 
frequency signal to a receiver which actuates a suitable alerting means 
Such a system is sold under the trade designation Poolside Alert, OPA-100, 
manufactured and distributed by Optex U.S.A., Inc. of Torrance, Calif. 
One major difficulty with passive infrared systems is that the sensed 
infrared energy can come from a great variety of sources other than a 
human intruder, such as, for example, sunshine directly impinging upon the 
sensor, reflected light, or a barbecue or grill in the vicinity, for 
example Also, to provide full protection where a pool has access from all 
sides it may be necessary to provide four sets of detectors and possibly 
four separate power supplies to achieve full protection 
SUMMARY OF THE INVENTION 
In the practice of the present invention there is provided an infrared 
light emitter which when energized forms a beam of infrared (IR) light The 
IR beam is directed onto a set of mirrors or reflecting surfaces arranged 
to form a closed path about the pool spaced above the pool decking a 
sufficient amount so it can be intercepted by anyone who might walk 
through it After the reflected beam has traversed the closed path about 
the pool, it then impinges upon an IR light detector Electric circuit 
means are provided which when the infrared light beam is intercepted by, 
say, a child who is unauthorized in the area, they provide a continuous 
alarm which can either be a sound or visual and which must be manually 
reset before it becomes inactive 
Although it is possible to enclose a given swimming pool within an intruder 
monitoring IR beam by the use of only two reflecting surfaces, in the 
usual case there will be three such surfaces located at three corners, for 
example, of the extended pool sides with the electrical apparatus for 
producing and detecting an IR beam being located at the fourth corner 
It is contemplated that the IR monitoring system is actuated to the 
operative state by a handheld radio frequency transmitter Electrical power 
for the system can be a rechargeable battery which is recharged by a solar 
array mounted directly onto a part of the system obviating the need for 
interconnecting cable wiring

DESCRIPTION OF A PREFERRED EMBODIMENT 
According to published sources, hundreds of children each year die from 
accidental drowning in domestic swimming pools in the U.S., or, receive 
brain damage as a result falling into the pool. These deaths and injuries 
occur even when there has been compliance with safety ordinances relating 
to fencing and locking of gates to prevent unauthorized access to swimming 
pool areas. It is, therefore, a fundamental aim and object of this 
invention to provide a system which will detect the presence of anyone, 
including a child, within a predetermined distance of the pool and 
activate an alarm so that the individual in potential danger can be 
readily located and removed to safety. 
Turning now to the drawings and particularly FIG. 1 there is shown a 
typical generally rectangular swimming pool 10 which is shown surrounded 
by a relatively flat cement deck 11 on which individuals can walk or from 
which they can dive into the pool water. The system, which will be more 
particularly described later, in its major elements includes apparatus 12 
fixedly mounted to the deck at a point outwardly of one of the pool 
corners that on being energized transmits a beam 13 of infrared light 
along a path above the decking 11 and generally parallel to one of the 
pool edges. A first reflecting unit 14 located outwardly of a second 
corner of the pool is so constructed and located as to reflect the 
infrared light beam from 12 along a path parallel to a second edge of the 
pool to a point where it is received by a second reflecting unit 15 which, 
in turn, sends the beam along a path parallel to the further pool edge 
where it is intercepted by yet another or third corner reflecting unit 16, 
the latter reflecting unit bringing the beam back to the apparatus 12. The 
returning beam, after it has traversed the closed path via the reflecting 
units 14-16, impinges upon an infrared detector mounted within the 
apparatus 12 which produces an electric signal indicative of the fact that 
the infrared beam has been produced and that the apparatus is in 
intrudermonitoring condition. When the light beam 13 is interrupted at any 
point along its reflected path, this causes an alarm signal to be produced 
by apparatus 12 activating an alarm 17, which may be audible, visual or 
both. 
It has been found that the best location for the IR monitoring beam 13 is 
approximately one foot from the pool edge and 2-4 inches above the 
decking. With the beam so located this permits leaves, bugs, and other 
foreign matter to blow or roll under the beam without setting off an 
erroneous alarm However, the beam is sufficiently high so that if a child 
moves into the range of the beam, it will immediately intercept it with 
its feet or other parts of the anatomy producing an alarm signal. 
FIG. 2 shows the application of the present invention to an unusual 
geometry or so-called "free-form" swimming pool 18. Although there are no 
straight sides to this pool, the apparatus 12 and corner reflecting units 
13-16 are still mounted to the decking 18 outside of the pool and in an 
arrangement to form a rectangular path. The fact that the straight lines 
along which the infrared beam moves may be at varying distance from the 
pool side does not inhibit operation or impair it in any way. It is still 
advisable with a pool of this shape that the beam be located 2-4 inches 
above the decking surface for reasons already given. The operation of the 
invention is identical to that for the more conventional rectangular pool. 
As can be seen best in FIG. 5, the IR beam generating and beam detection 
apparatus is mounted onto the upper surface of a base plate 19 having an 
integral positioning pin 20 secured to the lower surface of the plate at 
substantially its center point for a purpose to be described. An infrared 
light emitter 21 is edge mounted to a gimbal 22 which enables adjustably 
positioning the beam emitting surface of the emitter 21 in two orthogonal 
planes. The gimbal has a first generally U-shaped member 23 with its side 
arms rotatably connected to the emitter 21 via pins 24. The U-shaped 
member 23, is in turn, rotatably mounted onto a pedestal 25 which is 
secured to the base plate upper surface. Adjustment of the emitter about 
the axis of pins 24 is 90 degrees to the rotational axis of the U-shaped 
member on the pedestal 25, the combined effect giving full positional 
adjustment for the IR emitter. 
The apparatus 12 also includes a photoelectric means such as a solid state 
IR detector 26, for example, having a planar sensing surface and the edges 
of which are rotatably mounted within a gimbal 27 which can be of 
identical construction to the gimbal 22. With the gimbal adjustment 
centralized, the detector 26 faces outwardly from the base 19 along a 
direction 90 degrees from the direction that the IR emitter 21 faces when 
properly adjusted. Also mounted on the same base 19 is a power supply and 
alarm control logic 28. Still further, an RF transmitter 29 and associated 
antenna 30 are secured to the upper surface of the base plate 19, the 
antenna being connected to the transmitter and the transmitter being 
driven by the emitter/detector power supply and alarm control logic in a 
way that will be described. 
A transparent shell-like cover 31 for the apparatus 12 enables the exciting 
surface of the IR emitter 21 to emit the IR light beam 13 outwardly and 
the active parts of the IR detector 26 to receive the beam from reflecting 
unit 16 irrespective of the emitter and detector. 
In assembly, a suitable opening is formed in the deck 11 at a position 
which forms the corner of a desired rectangular IR beam traversal path 
with the emitter 21 and detector 26 facing towards the path corners where 
reflector units 14 and 16 are to be located, respectively. The base plate 
pin 20 is then positioned in the deck corner opening and the emitter and 
detector properly located to face along adjacent lines forming a corner of 
the IR traversal path. Then, one or more bolts 32 are received through the 
base plate and secured with the deck fixing the entire apparatus 12 
against unitary translation or rotation. 
Each of the corner reflectors 14 through 16 is identical in construction 
and therefore only the reflector 14 will be described, it being assumed 
that for the other two, the same numbered parts will be represented in 
each. The reflecting means 14 has a base plate 33 of any suitable outline 
geometry and including a pin 34 integral therewith extending from the base 
plate lower surface at substantially its center point. One or more 
openings 35 are formed in the base plate for mounting the reflecting means 
to a swimming pool deck, as will be described. 
With reference to FIG. 3, a reflector such as a mirror 36, for example, is 
mounted within a generally Ushaped gimbal 37 relative to which the mirror 
is rotatable about an axis defined by two edge connecting pins 38. The 
gimbal 37 has its cross member affixed to a rotatable pedestal 39 which is 
substantially centrally located on the upper surface of the base plate 33. 
By this mounting arrangement, the reflector 36 may be suitably located for 
directing an IR beam, as will be more particularly described, along a 
desired path. 
Mounting of each of the reflecting means 14 through 16 to the swimming pool 
deck is similar to the way in which the apparatus 12 already described is 
mounted. More particularly, an opening is formed at what is determined to 
be the precise corner of the desired IR path and a pin 34 fitted therein. 
One or more bolts are then extended from the top side of the base plate 33 
downwardly through openings 35 for receipt within other openings in the 
cement and thereby secure the entire reflecting means against rotation or 
translation with respect to the deck. 
Each reflector unit is enclosed within a cylindrical or cup-shaped 
transparent cover 40 which can either be snapped or threaded onto the base 
plate. The transparent wall of the cover 40 allows the reflecting surface 
of the reflector 36 to receive and reflect light in accordance with the 
practice of this invention throughout the entire circumferential 
periphery. 
The top wall on the outer surface of the cover 40 includes a molded-in or 
embossed pair of alignment lines 41, 42 arranged at 90 degrees to each 
other which serves to assist in initially lining up the reflecting means 
during mounting to the decking (FIG. 4). 
Reference is now made to FIG. 8 which depicts the circuit schematic of the 
overall apparatus of the invention. A battery power supply 43 (also 
identified in FIG. 5 as 28) provides the necessary electrical power 
through a low voltage sensor 44 and main relay 45 to energize the IR 
emitter 21, IR detector 26, logic 46 (shown combined in FIG. 5 at 28) and 
the radio frequency transmitter 29. The power supply 43 may be any of a 
number of different available kinds, but preferably a rechargeable 
battery. An exceptionally advantageous power supply for present purposes 
is achieved by connecting a solar array 47 to charge the rechargeable 
battery power supply. The solar array can be mounted on the top of the 
apparatus 12 under the transparent cover. 
In operation, a remote control unit 48 is activated which sends an RF 
signal to receiver 49 to enable the main relay 45 and in that way apply 
electrical power to the various system parts as has been described. The 
emitter 21 produces an IR beam 13 which as long as it is not interrupted 
actuates the detector 26 and logic 46 to produce a "down" or zero signal 
to transmitter 29. When the beam 13 is interrupted by an intruder, for 
example, there is a corresponding interruption of the IR detector signal 
which on interpretation by the logic 46 produces an "up" signal to 
transmitter 29. Energiziation of the transmitter in this way sends a 
signal to an RF receiver 50 which then actuates the alarm 17. The alarm 
will continue operating until it is affirmatively reset at 51. 
If the biasing voltage of battery power supply 43 becomes too low, the 
system may not be able to respond to an interrupted IR beam. Accordingly, 
the low voltage sensor 44 on noting a low voltage condition lights a 
warning light (LED) 52 and through the logic 46 sets off the alarm 17. 
When this happens the battery supply 43 must be brought up to proper 
voltage in order to continue.