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Publication numberUS3504145 A
Publication typeGrant
Publication date31 Mar 1970
Filing date17 May 1967
Priority date17 May 1967
Publication numberUS 3504145 A, US 3504145A, US-A-3504145, US3504145 A, US3504145A
InventorsFrancis W Layher
Original AssigneeFrancis W Layher
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Circuit operating device for swimming pool alarm system
US 3504145 A
Abstract  available in
Previous page
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Claims  available in
Description  (OCR text may contain errors)


ATTORNEYS March 31,1979 jjgwJJ i-lza 3,50

cmcim oafim'rme nrfi'iircm F'bn swmmne soon ALARM SYSTEM mm 17, 19s? z Sheets- Sheet a I511 OK I6 I INVENTOR.


F 4 m 0' KW ATTORNEYS United States Patent Oifice 3,504,145 Patented Mar. 31, 1970 3,504,145 CIRCUIT OPERATING DEVICE FOR SWIMMING POOL ALARM SYSTEM Francis W. Layher, 713 Henrietta Ave., Sunnyvale, Calif. 94086 Filed May 17, 1967, Ser. No. 639,083 Int. Cl. H01h 35/18 US. Cl. 200-84 2 Claims ABSTRACT OF THE DISCLOSURE A swimming pool alarm system includes an elongated buoyant container equipped'with a pair ofelectrical contacts which, when closed, initiate an audible alarm. A buoyant float member contained within the elongated container operates the contacts, and, due to its considerably smaller mass as compared to the mass of the elongated container, the inner float member more readily responds to Waves within the pool. Both buoyant members are in open communication with the Water of the pool. Waves generated in the pool by objects falling into it, being of considerably higher frequency than waves generated by the natural elements, such as wind, cause the inside float to quickly rise relative to the container, and actuate the contacts to initiate the alarm. The lower frequency waves serve to elevate both the float and the container with little relative movement therebetween.

This invention relates to alarm systems and more particularly to a swimming pool alarm system of a type serving to produce an alarm upon the occasion of an object falling into the water of the swimming pool as distinguished from waves caused by wind and the like. As will be readily apparent, the alarm system is also suitable for other bodies of liquid, such as water tanks and the like.

Swimming pools, particularly privately owned residential pools, have long been recognized to present a considerable hazard with respect to small children falling into them when they are unattended. To this end, many municipalities have required fencing to be placed about all swimming pools and locks applied to the gates. While this measure, to a certain extent, serves to preclude the possibility of a small child entering the premises and falling into the swimming pool at a time when it is unattended various other measures have been taken due to the gravity of the hazard involved.

Certain of these measures have included the provision of alarms for the purpose of detecting waves formed in the swimming pool as might be occasioned by an object falling into the water. Such alarm devices have been somewhat unsuccessful and in large part, their lack'of success can be attributed to the fact that the wind or other elements can serve to activate the alarm so as to generate many false alarms.

I have observed, however, that the wind and other elements will form waves having a relatively low frequency. Thus, the peak to peak distance between successive waves is somewhat widely spaced as compared to waves generated by objects falling into the water.

Taking advantage of the above observation, there has been provided herein a device for initiating an alarm in response to relatively high frequency waves as distinguished from the relative low frequency Waves noted. In this manner, the device senses the occasions wherein an object has fallen into the water as distinguished from other activity which may generate waves in the swimming pool. Accordingly, false alarms are minimized.

In general, it is an object of the present invention to provide an improved alarm system for warning that an unattended pool has been entered by a body, such as a child or other object.

As disclosed herein, there is provided an alarm device for warning that an object has fallen into a body of water and in which device a means has been provided for adjusting the sensitivity of the device so that a predetermined limited threshold of activity must occur prior to sounding the alarm.

Thus, it is a further object of the present invention to provide an alarm system capable of being adjusted with relative simplicity so as to further minimize false alarms.

These and other objects of the invention will be more readily apparent from the following detailed description of preferred embodiments when considered in conjunction with the accompanying drawings, in which:

FIGURE 1 is a perspective view showing a swimming pool alarm system, according to the invention;

FIGURE 2 is an enlarged vertical section of the sensing uniyt shown in FIGURE 1;

FIGURE 3 is a schematic system, according to the invention;

FIGURE 4 shows an electronic circuit for operating the system, according to FIGURE 3; and

FIGURE 5 is an enlarged vertical section view of another embodiment of the sensing unit, according to the invention.

Referring to FIGURE 1, an alarm system is shown comprising generally of a sensing apparatus or unit 11 floating in the water 12 of a pool, such as a swimming pool, and an alarm unit 13 coupled thereto by a pair of electrical leads such as the bi-filar conductor 14. In general, unit 11 is arranged to ride freely in the water with its only attachment being the electrical connection 14.

According to the system disclosed herein, unit 11 is adapted to sense those waves of at least a predetermined frequency and higher indicative of a body falling into the water, such as a small child or other such disturbance. On such occasions, an alarm is signaled by unit 13. The alarm signal remains on notwithstanding the fact that waves of such frequency may have ceased and will remain on until turned off by operation of switch 16.

The sensing unit 11 comprises an elongated cylindrical housing 17 formed from a pair of elongated molded shells 18 of identical construction.

Each shell is formed from a suitable buoyant material such as the popular ABS plastic and comprises a solid lower ballast portion 19 for disposing housing 17 generally upright in the Water. The interior of housing 17 is in open communication with the water in the pool by means of a port 21 formed through the side of shell 18 just above ballast portion 19.

In order to hold the two shells 18 together to form housing 17, a pair of rivet holes 22, 23 have been formed transversely of the longitudinally axis of housing 17 through each shell 18. The lower rivet hole 22 includes an enlarged opening 24 which serves to accommodate the passage of the head of a rivet so as to avoid providing an obstruction on the outer side of shell 18. Similarly, rivet hole 23 has been formed with a recess 26 to accommodate the head of a rivet. Around rivet hole 23, on the inside of shell 18, there is provided a protruding portion 27 forming a lower stop for the longitudinal movements of a relatively lightweight sensing float 28, preferably of Styrofoam material coated by an application of suitable sealant.

The mass of float 28 is considerably less than that of housing 17 whereby float 28 responds far more readily to waves in the pool than does housing 17. Accordingly, float 28, when subjected to relatively high frequency waves is free to move along housing 17 and into engagement with a pair of electrical contacts 29, 31 located at 3 the upper end of housing 17, of stainless steel plated with a noble metal so as to remain rust free. Accordingly, float 28 is free to move between contact closing and contact opening positions to operate contacts 29, 31.

Means supporting contacts 29, 31 comprises a circular disc 32 of insulating material upon which contact 29 is secured. Contact 31 is spaced by means of the insulation 33 from contact 29. The two contacts are carried at the upper end of housing 17 by insertion into the grooves 34 or notches molded into the upper ends of each shell 18.

Finally, a bi-filar conductor 14, comprising a pair of leads, each of which is coupled to an associated one of contacts 29, 31 is led through an opening 36 formed in the upper end of housing 17. In order to prevent forces acting on lead 14 from damaging the connections made with contacts 29, 31, lead 14 includes a knot 37 which accepts any force applied to lead 14 from outside housing 17.

Conductor 14, after passing out of housing 17, extends tightly down the side of shell 18 between the shell and an encircling buoyant ring 38. Ring 38 is preferably produced from polystyrene which is sealed by a suitable coat of sealant to prevent it from becoming water logged.

Ring 38 moves slidably in a tight fit along the exterior of housing 17 in order to adjust the buoyancy of unit 11 whereby housing 17 can ride higher or lower in the water as desired. This serves to adjust the sensitivity of sensing unit 11.

Fixed stops 40 are molded to protrude from the exterior of housing 17 at positions beneath ring 38. Stops 40 are located at positions which preclude ring 38 from being slidably moved to an inoperable position for unit 11.

With respect to contacts 29, 31, it has been found desirable to form them in a manner which leaves a sharp surface adapted to penetrate residual films and thereby insure contact. Further, due to the exposure which unit 11 is subjected to, it is desirable to construct contacts 29, 31 from the suitable materials mentioned above.

By directing conductor 14 downwardly along the side of housing 17 to a point where it trails away from unit 11 from beneath ring 38, it has been found that the wind will have little effect upon the generally upright positioning of unit 11. On the other hand, if conductor 14 trails directly away from'opening 36, the general disposition of sensing unit 11 will be at a sloping angle as the wind will cause it to tip.

The functioning of unit 11 proceeds generally as follows having in mind the general objective of closure of contacts 29, 31 upon experiencing waves having a relatively high frequency (i.e. close peak to peak spacing) as distinguished from those having a relatively low frequency.

Float 28 and housing 17 are both in free communication with the water of the pool. The buoyancy of housing 17 (and sensitivity of unit 11) can be adjusted so that it rides higher or lower in the water by merely sliding ring 38 longitudinally thereof.

As ring 38 is slidably moved to a lower position, unit 11 will ride higher in the water. Accordingly, float 28 will have a greater distance to travel upwardly within housing 17 in order to engage and enclose contacts 29, 31, wherein it becomes less sensitive.

Contrariwise, slidable movement of ring 38 upwardly along housing 17 will render unit 11 considerably more sensitive inasmuch as the distance of travel for float 28 is reduced.

It has been found that with a relatively low frequency wave, both float 28 and housing 17 will experience the wave and rise generally together thereby generating relatively little or no relative movement between the two. On the other hand, with relatively high frequency waves, due to the considerably smaller mass of float 28 as compared to the generally greater mass of housing 17, float 28 will quickly rise whereas housing 17 is subject to some delay in rising with the wave. This, of course, generates a relative movement between float 28 and housing 17 and, if suflicient relative movement occurs, float 28 will engage and close contacts 29, 31 (FIGURES 3 and 4).

Means have been provided which initiate an alarm upon the closure of contacts 29, 31 as now to be described.

In general (FIGURE 3), such closure serves to'operate a switching function wherein the closure of the contacts is a pick signal, and once picked, the switch will remain held in operation. Thus, broadly, unit 11, upon closure of contacts 29, 31, serves to pick switch 39.

Once picked switch 39 initiates a holding circuit for energizing an alarm 41 powered by the power supply 42.

As shown in the detailed circuit of the drawing (FIG. 4), a circuit is arranged which includes a power supply in the form of a battery 43, the on-ofi switch 16 and a silicon controlled rectifier (SCR) 44. SCR 44 functions ordinarily to preclude the passage of current through it in one direction while passing current in an opposite direction. However, upon being subjected to a particular control signal, a breakdown is caused in SCR 44 which permits conducting to occur in the opposite direction.

Operation of the circuit as shown in the figure proceeds as follows:

Assuming that on-otf switch 16 is in its closed position, SCR 44 will block conduction from battery 43 through alarm 41 (shown in the form of an inductance operated horn) preferably located outside of the casing 56 of unit 13 so as to enhance its audibility.

However, upon closure of contacts 29, 31, a triggering voltage is applied across terminals 46, 47 which causes a breakdown of the rectifying or blocking action of SCR 44. In this condition, a circuit can then exist through the coil 49 of alarm 41 traced as follows from the negative terminal of battery 43, thence along conductor 48 and through coil 49 so as to operate alarm 41. From coil 49, the circuit is completed along lead 51, through SCR 44 (now in its reverse conducting condition) and thence back to the positive terminal of battery 43.

The triggering voltage across terminals 46, 47 was initially generated by means of closing the contacts 29, 31. This had the effect of placing voltage derived through resistances 52, 53 across terminals 46, 47. This triggering voltage was generated, therefore, by the circuit traced from the negative terminal of battery 43 through resistance element 52 and resistance element 53 (then in a series connection) and thencethrough contacts 29, 31 to terminal 47 of SCR 44 via conductor 54. From terminal 47 the circuit continues through switch 16 to the positive terminal of battery 43.

A preferred disposition of the alarm system, as shown in FIGURE 1, includes a casing 56 for alarm unit 13. Unit 13 is chained by means of the lightweight chain 57 to any suitable permanent construction located about the swimming pool and Within reach of the water by means of conductor 14. By attaching the chain 57 to the back of unit 13, it will be apparent that the speaker 41 will generally be disposed away from the water area and therefore be less subject to becoming damaged by water. It is preferred, of course, to employ a speaker of substantially all metal construction such as stainless steel as distinguished from those speakers employing a diaphragm readily subject to damage. Diaphragm speakers covered with a fine mesh stainless steel screening can be employed where the mesh precludes passage of water but not sound.

According to another embodiment of the invention (FIG, 5), there is provided, in general, a first buoyant member 58 in the form of an enlarged annular ring having an open core. A portion of the interior of the ring has been cut away to form a pocket 59 to accommodate the bobbing movements of a float 61 within the open core of member 58. Float 61 of considerably less mass than member 58 carries a pair of contacts 62, 63 and a counterweight 64.

Leads 66, 67 extend upwardly from float 61 and include a reverse loop to accommodate the up and down movements of float 61 relative to member 58.

In order to adjust the sensitivity of this embodiment a ring 68 is slidably carried along the outside of. member 58 so as to adjust the sensitivity of contacts 62, 63.

From the foregoing, it will be readily apparent that there has been provided herein two embodiments of a device for initiating an alarm signal as respects a pool of water or other liquid. The device comprises a first and second buoyant member each of which is in open communication with, and adapted to ride freely in, the water. These two members are relatively movable in a predeter mined direction with respect to each other although one is generally confined as to relative movement laterally with respect to the other. A pair of contacts is carried by one of the members, The other member is movable with respect to the last named member in a predetermined direction between contact closing and contact opening posi-- tions so as to operate the contacts. The mass of one member is considerably different from the mass of the other whereby the member having the considerably lesser mass responds much more readily to the waves in the pool than does the other member.

In practice, it has been found that merely slapping the water with ones hand when the pool is otherwise quiet will serve to set ofl? the alarm. Waves generated by the wind will not, however, set it ofi.

What is claimed is:

1. A device for closing the circuit of an electric alarm to operate said alarm as respects disturbances in a pool of water comprising a first buoyant member forming a hollow body adapted to ride freely in the water and having an open flow passage therein adapted to permit Water of the pool to pass freely into and out of the hollow interior of the body, and a second buoyant member within said body and movable to ride freely upon the water within said body and independently thereof relative to said first body, said second member being free of connection to said first member, the sole and last remaining electric contacts for activating the circuit of the alarm being carried by only one of said buoyant members, the other buoyant member serving to move with respect thereto into and out of engagement with said contacts to operate said contacts while both said members ride independently of each other upon the surface of the pool free of connection therebetween, and means carried by one of said members and variously positionable with respect thereto to cause the last named said one member to ride higher or lower in the water to vary the degree of movement required of the other member in operating said contacts.

2. A device for closing the circuit of an electric alarm to operate said alarm as respects disturbances in a pool of Water comprising first and second buoyant members adapted to ride freely in the water, the contacts for closing the circuit of the alarm being carried by only one of said buoyant members, the other buoyant member being free of physical connection to said one buoyant member and movable free of restraint relative thereto into and out of engagement with said contacts to operate same, both of said members riding freely and independently of each other in the pool, the mass of one of said members being considerably greater than that of the other to respond more readily to waves in said pool than does the other member, and means slidably carried by one of said members and variously positionable with respect thereto to cause said one member to ride higher or lower in the water to vary the degree of movement required of the other member in operating said contacts.

References Cited UNITED STATES PATENTS 2,717,935 9/1955 Hartwick 20084 3,058,101 10/1962 Malvini. 3,204,232 8/1965 Meyer 20061.2

ROBERT K. SCHAEFER, Primary Examiner D. SMITH, Assistant Examiner US. Cl. X.R. ZOO-61.2; 340244

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2717935 *26 May 195213 Sep 1955Milton Hartwick CharlesSafety device for hydraulic brakes
US3058101 *26 Jun 19599 Oct 1962Rocco J MalviniPool safety device
US3204232 *5 Nov 196331 Aug 1965 Alarm for swimming pool
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3757318 *22 Oct 19714 Sep 1973Brisson Dev IncSwimming pool safety device
US3778803 *27 Sep 197111 Dec 1973D JahnSwimming pool guard alarm unit
US4191951 *16 May 19774 Mar 1980Caterpillar Tractor Co.Device for sensing fluid forces
US4265598 *15 Sep 19785 May 1981Brand Stanley WApparatus and method for de-actuating swimming pool equipment
US4476648 *4 Feb 198316 Oct 1984John MaximFloat activated toy vehicle
US4510487 *10 Mar 19829 Apr 1985Aaron Alarm Systems, Inc.Pool alarm
US4747085 *24 Feb 198624 May 1988Gerald W. DuneganMethod and apparatus for monitoring swimming pools
US5245834 *22 Jul 199221 Sep 1993Samsung Electronics Co., Ltd.Condensate tank of a dehumidifier
US5306885 *9 Sep 199226 Apr 1994S. J. Electro Systems, Inc.Cable attaching device
US5959534 *4 Nov 199728 Sep 1999Splash Industries, Inc.Swimming pool alarm
US9612230 *24 Aug 20154 Apr 2017Miura Co., Ltd.Water quality measuring device
US20090046889 *14 Aug 200719 Feb 2009Cheng Uei Precision Industry Co., Ltd.Speaker
US20150362471 *24 Aug 201517 Dec 2015Miura Co., Ltd.Water quality measuring device
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WO2001088871A1 *17 May 200122 Nov 2001AslodisDevice indicating the fall of a body in a water expanse
U.S. Classification200/84.00R, 340/624, 340/573.1, 200/61.2
International ClassificationG08B21/08, H01H35/18
Cooperative ClassificationH01H35/18, G08B21/084
European ClassificationG08B21/08M, H01H35/18