EP0484184A1

EP0484184A1 - Life-saving alarm for persons in a water medium

Info

Publication number: EP0484184A1
Application number: EP91310141A
Authority: EP
Inventors: Alfredo Tadeo Diaz Valdez
Original assignee: Individual
Current assignee: Individual
Priority date: 1990-11-01
Filing date: 1991-11-01
Publication date: 1992-05-06
Also published as: MX9101863A; ZA918658B; KR920010521A; BR9104729A; JPH04274598A; CA2054532A1

Abstract

An alarm system for detecting persons who accidentally fall into water and who may be in the water in an emergency situation that requires help, of the kind comprising a signal transmitter means (20) including an activating means (23) for actuating said transmitter means which is sensitive to a pre-determined condition, said transmitter means being attachable to the body of a user by removable means of attachment, characterized by at least one receiver means (21) for receiving said transmitted signal and capable of identifying the signal and of controlling an alarm device disposed at a place where help is available.

Description

This invention relates to a safety system, and more particularly to a life-saving alarm for persons in a water medium.
Even more particularly, it is an object of this invention to provide an immersion alarm (or an immersion sensor) intended to save the lives of persons, either children or invalids who accidentally fall into the water, and even persons practising water sports, or swimmers, in an emergency situation.
The invention relates to a protective element to be used mainly by those persons who are not able to swim, in case they fall into the water by accident or are totally or partially unable to make the minimum necessary movements to keep floating.
At the same time, the protective element allows these persons to be in the water playing or amusing themselves without any risk to their lives. Likewise, the element can be used by persons who, even when they can swim, can find themselves in a dangerous situation (cramp, tiredness, watercurrent dragging, injury, etc.).
In brief, the present invention is characterized by the features set out in the characterizing portion of claim 1.
In a preferred form of the invention the alarm means to be attached to the body of the user may be in the form of a necklace, belt, wrist strap, etc. Said alarm means may for example be activated when in contact with water to cause a signal to be emitted.
The invention also contemplates an apparatus receiving said signal, which should be located within a suitable sensing range, so that, when the receiver senses said signal this means that the immersion in water of the person equipped with the alarm means has been detected, and consequently an alert is given in this emergency situation. In such a case, the receiver may in turn activate an audible (or other) alarm device located at a place where help can be given to the person in danger.
It can also be stated that the presence of children at the seaside, or in rivers, ponds, swimming pools, or any other water medium, has always been a source of constant worry and anxiety to their parents, considering the large number of deaths and accidents related to asphyxia by immersion (drowning), especially affecting all children who cannot swim.
Regarding the use of electronic media to detect and prevent aquatic accidents produced by asphyxia by immersion, even if there are some existing versions, they have up to now given poor results because the scarce systems developed until the present time have not succeeded, as yet, in solving aspects of fundamental importance for an effective safeguard of the physical integrity of persons.
This is mainly due to the fact that the methods or elements used lack three basic requirements: reliability, practicality and simple installation. For these reasons, the use of the same has not been widespread or they have failed, since all existing types of apparatus have serious disadvantages.
U.S. Patent 3810146, referred to herein as the "Lieb" patent, disclosed an alarm device which was unsuccessful, precisely due to its significant technical and structural deficiencies.
We shall below mention the main disadvantages of the device disclosed in the "Lieb" patent:

1. It is inspired by the emission of ultrasonic signals or waves and, on account of said signals being extremely directional, the transmitter supposedly placed on the chest of the user should be directed to or "aimed" directly towards the receiver installed somewhere in the pool. It is absurd to think that a person who is drowning will keep still in the water during the emergency and that, simultaneously, his signal transmitting apparatus will be exactly "aiming" at the element meant for receiving the signal.
2. So that the ultrasonic signal transmitter described in the "Lieb" patent had the power and range necessary to fulfil its functions in a pool of ordinary size, as for instance a pool of 4 m x 5 m, it should have an ultrasonic transducer and large batteries. In order to appreciate the lack of practicality or the non-viability of the "Lieb" patent in this respect, we should imagine a child equipped with a transmitter with the described elements: it would be so bulky and heavy, that it could not be carried hanging from his neck because it would be similar in size to the battery of a car.
3. The "Lieb" patent is exclusively for use in swimming pools. That is, it has not been meant for use in the sea, rivers, lakes, or any other water medium.

To date, such accidents were mostly prevented by a simple permanent visual observation of small children, which, obviously constitutes a highly unsafe precaution.
On the other hand, in crowded places of aquatic amusement and entertainment, an additional control is usually implemented by means of lifeguards. However, since such control is also a visual one, it is as unsafe and as subject to failure as the previous one.
Another widely implemented alternative has been that comprising the use of life-jackets or belts. However, children usually refuse to wear them as such life-saving devices limit their movements and, in addition, they are rather uncomfortable when wet. For this reason, children often take off the life-jackets or belts without their parents noticing and thus remain wholly unprotected.
For the particular case of swimming-pools, and the prevention of accidents by immersion therein, there are other methods which have not been yet referred to but which shall be described hereinafter so as to show disadvantages involved in their use. Such methods include perimetral fences, a certain kind of protecting fence, as well as several kinds of coverings or nets. Below are only some of the drawbacks found in such arrangements:

(a) It offers children a real amusement or "adventure" to climb or overcome such obstacles.
(b) Children can usually pass over such fences with the misguided co-operation of other children.
(c) By carelessness or negligence of a user, the door on the fence for access to the pool can be left open.
(d) People coming in or out of the water can get injured, for example if they are bare-footed when stepping on the means of engagement or anchoring of such fences.
(e) Such protective means tend to cast shadows on the solarium itself and, in addition, they lack aesthetic appeal.
(f) An annoying discrimination is made between those children who can remain in the pool and those who, because they are unable to swim, can only watch the others playing, from behind the fence.

It is to be noted that existing prevention systems made it difficult and even impossible to determine if someone is immersed in the water and urgently needs help in such an emergency. Consequently, it can be said that none of the known methods allow non-swimmers to enjoy their healthy aquatic entertainment or a refreshing bathe without any fear or risk, in the sea, river, lakes, pools, etc.
On the other hand, as is widely known, death by immersion also affects old people and even expert swimmers in critical situations such as on account of cramp, water current towing, physical tiredness, etc.; these accidents can occur not only in seas and rivers but also in lakes and swimming-pools. Think only of the number of lives that could have been saved, should such people have been able to receive immediate assistance in the emergency.
As a result, the invention disclosed in this specification provides an ingenious and effective solution to the above-mentioned problems and allows the presence of children near seas, rivers, ponds, swimming-pools or any water medium, without any annoying discrimination but nevertheless noticeably decreasing the risks of any accidents caused by drowning (asphyxia by immersion).
Therefore, the invention herein contained solves the above referred difficulties, on the basis of an alarm means which, once attached to the body of the user (e.g. a child), for example in the form of a necklace, belt, etc., allows parents to be on the alert as soon as the child enters the water; alternatively, if desired, the child may be allowed to remain safely in the water as long as the neck is not immersed. Furthermore, as above indicated, in the case of swimmers facing critical situations, they may be able to press a switch to activate the alarm.
The alarm means may consist of an immersion sensor connected to a transmitter to send a remote signal through a short distance to a receiver which, when said sensor comes into contact with water, receives a signal activating the alarm. Thus, it is possible to know immediately when the person to whom the device has been attached has entered the water or has accidentally fallen in, and also to have enough time to take the necessary steps to save the person (either in the sea, river, swimming-pool, etc.).
In the case of an elderly person, or of a swimmer in emergency, the system is when necessary activated, not automatically, but by means of a release device such as a push button, etc.
This invention has also ingeniously solved other troublesome aspects:

(a) The receiving means (or the transmitter, as desired) may comprise a device which functions to prevent the alarm being operated by mere water splashing or a brief immersion (i.e. the alarm is operated only after some seconds and new warning elements are subsequently activated).
(b) This invention can be used in open water (sea, river, etc.) without the need to enlarge the size of the signal transmitter; it should be noted that, in order to be attached to the user's body, the remote signal transmitter should necessarily be small and easy to carry, as well as an aesthetically pleasing element).

For the above-referred reasons, for use in open water or over long distances, the invention additionally comprises a perimetral antenna, one or more buoys, or an arrangement of posts, piles, rock fills, walls, etc., equipped with repeaters to receive the signals from any activated transmitters and to re-transmit the same with greater strength and at longer range.
On the other hand, in highly crowded places (such as beaches or water mediums of normal size), it is not sufficient to receive a corresponding alert signal and so learn that an unknown person among the number of people present is in an emergency situation on account of water immersion. Then, it becomes necessary to also determine the exact location of the particular person in the water, so as to help him/her immediately. Therefore, the exact location of the person in danger in highly crowded places is determined by the use of a monitor or computer interface which, by means of radiogonometry or triangulation by buoys or receivers disposed in posts, piles, rock fills, walls, etc., accurately detects the place where life saving is required.
For all the above reasons, it becomes easy to imagine the degree of acceptance this system will have once adopted, regardless of the category of use it may then have. Furthermore, on account of the characteristics defining it, it can be used either by children, old people or invalids, and even by competent adults and expert swimmers, both in summer resorts and in the country, clubs, farms and weekend houses, including the home; in general it can be used in any place in which people can accidentally fall into the water or be in any life-threatening emergency situation within a water medium.
In order that the present invention may more readily be understood the following description is given of one preferred embodiment, merely by way of example, with reference to the accompanying drawings, in which:-

FIGURE 1 is a block diagram which shows as a flow diagram of the life-saving device, both the means for producing the alarm signal and the means intended to receive and to amplify said signal;
FIGURE 2 illustrates in more detail the circuit of the remote signal transmitting means;
FIGURE 3 shows a diagram of the signal-receiving circuit;
FIGURE 4 is a perspective view of an open, band such as a collar or bracelet, showing the life-saving means both as to the general structure thereof and the arrangement of the different parts and elements forming said means;
FIGURE 5 is a view of the collar of Figure 4 closed and attached to a child's neck;
FIGURE 6 is a schematic view of an arrangement whereby the location of the means transmitting the remote signal can be also located within a large water medium;
FIGURE 7 shows a block diagram of the circuit of another form of the embodiment of Figure 6; and
FIGURE 8 shows another embodiment shown as a plan view of a swimming-pool surrounded by a perimetral antenna, which communicates to a central receiver connected to the alarm means.

It is clear that the use of such perimetral antenna is advisable only for the case of extraordinarily large swimming pools. For swimming-pools of ordinary dimensions, the power of the transmitter will be sufficient by itself to be received by the antenna of the receiver.
The alarm device consists of a transmitter means 20, of a UHF or VHF modulated high frequency remote signal, which in turn comprises an activating means 23 for activating said transmitter means, which is carried by the user on a holder element 24. The system is completed by a receiver means 21 for receiving the signal emitted by the remote transmitter means 20, when activated by the activating means 23. The receiver means 21 is connected to an alarm device 25 which is operated when the receiver means 21 receives the signal from said transmitter means 20.
This receiver means 21 is arranged at a fixed place remote from said transmitter means 20. The signal transmitter means 20 as shown in Figure 2 comprises a high frequency stage formed by a high frequency N-P-N transistor TRI connected to the tuned circuit formed by LI and CVI, CVI being variable in order to fix the frequency.
In series with the collector-emitter path of transistor TRI is a resistor RI which limits the current and is connected to ground.
Between the power supply and the base of transistor TRI, is a bias resistor R2, and between the transistor base and the tuned circuit is a feedback capacitor CI.
The choke ZI connected to the output of the tuned circuit attenuates the radio frequency flow to the power supply, and the capacitor C2 limits the radio-frequency existing in the emitter of TRI.
The modulation frequency is received at the base of transistor TRI through diode DI.
The low-frequency stage generating the information to be modulated comprises the integrated circuit ICI which connects the output of contact 17 to ground according to a predetermined code established by a combination of ground-connecting contacts 1 to 12 of ICI.
In a preferred form of embodiment of this invention, the integrated circuit ICI is MM53200N.
During the time in which ICI pulls the DI voltage and in consequence the TRI base to positive, the oscillator is deblocked and emits a series of carrier waves.
Contact 13 of ICI constitutes the input of the local oscillator of the integrated circuit, which is connected to the RC network formed by R3 and C3 and which fixes the clock frequency of the low frequency stage. The LED diode DLI, further to operating as a resistance to adjust the supply voltage, is also useful for detecting the correct operation of the signal transmitter since, when activating means 30 is closed, the diode DLI sets the anode to the positive supply voltage, and flashes with the power supply voltage.
Apart from being part of the tuned circuit, the coil LI also operates as transmitting antenna, whereby the signal transmitter has highly reduced dimensions.
The signal receiving means 21 is shown in more detail in the circuit diagram of Figure 3, the operation of which will be hereinafter described.
The signal coming from the antenna ANT is received at the base of the transistor TR10 after passing through the capacitor C12. Both TR10 and C12 form, together with the tuned circuit L10-CV10 and network R10-D10 and R14 (the base biasing of transistor TR10), a superreaction type of receiver.
Capacitors C13 and C14 and choke ZI determine the reaction frequency for detecting the signal.
This detected PCM signal, once filtered by the low-pass filter formed by R13, C15 and C16 to eliminate the high frequency component of the signal, is then amplified by TR12, which together with low resistance R16 and base polarization resistance R17 constitutes a high-gain amplifier.
The signal filtered by capacitor C17 is then amplified by transistor TR13 which is connected to the emitter resistor R21 to limit the capacity of the amplifier. Pass-band clipping capacitor C19 is further connected to the collector and to the base of transistor TR13.
The output of this amplifying stage is coupled with the base of transistor TR14, by means of capacitor C20 and diode D15, once the signal has been rectified by means of diode D12 and filtered by capacitor C21.
The following stage comprises a Schmitt trigger, formed by transistors TR14 and TR15, and whose switching threshold is determined by the resistor R27.
A square wave signal which is emitted from the TR15 collector, is almost free of distortion and is applied on contact 16 of an integrated circuit IC2 known per se.
This PCM signal is compared at IC2 with the shape of the signal which, once previously programmed, is memorised and, in the case of coincidence, is connected to ground contact 17 of IC2.
Once ground-connected, the base of a PNP transistor TR16, connected to contact 17 of the IC2 by resistor R29, operates the transistor and biases the base of transistor TR17, which is connected to the divider formed by resistors R22 and R32 thus saturating the transistor and activating the coil of relay RL1, closing contacts C-B and connecting supply to the transducer Bo that omits the audible alarm signal.
The portion of the circuit appearing at the top is a conventional stabilized continuous current power supply circuit and is included only as reference for the case in which the circuit is connected to a 12V battery; it therefore does not need to be described in any detail herein.
In this embodiment the activating means 23 is formed by two electrodes, referenced 30 in Figure 2, which close the circuit when immersed in water.
In order to improve sensitivity of the immersion sensor, an amplifying stage can be included between electrodes 30 and the supply circuit.
Similarly, a circuit for controlling the activating means can be included, to allow detection of a temporary closure of the circuit activated by electrodes 30 without operating the alarm (e.g. as a result of a mere splash or by only a brief immersion). Such control circuit is not herein illustrated as it is widely known in the art.
The audible alarm device 25, connected to receiver means 21 for receiving the remote signal, is formed by an acoustic transducer referenced as Bo in Figure 3.
The alarm device 25 can be of progressively increasing intensity.
In operation of the alarm system of the present invention the holder element 24 is attached to the user, either by the neck, wrist, waist or ankle, etc., depending on whether the transmitter is expected to operate when the user just enters the water (ankle), the water level exceeds a particular limit (waist) or when the water reaches a level of total prohibition or danger (neck).
Receiver means 21 for receiving the remote signal is arranged near the water medium, so that when a user carrying the remote signal transmitter means 20 enters the water and the activating means 23 becomes below the surface of the water medium, the transmitter means is activated and the respective signal is received by the antenna and then amplified, thus activating the alarm device 25 which indicates that the user is in the water with the activating means 23 below the water surface; the alarm device 25 consequently warns the persons in charge of the control and/or surveillance so that they can assist the person in an emergency situation.
In the above-described particular case, the remote signal transmitter 20 may operate as a UHF or VHF high-frequency system; a modulation frequency indicative of a respective one of several users can be designed, and associated with different kinds of alarms so that it will be possible to determine which of the various users in the water medium is the one with the activating means 23 below the water surface. This is due to the fact that the integrated circuits applied to the signal transmitter means 20 and to the signal receiver means 21 can be programmed.
The embodiment illustrated in Figure 8 offers the possibility of having the antenna of the remote signal receiver means 21 formed by a frame antenna 31 perimetrally disposed with respect to the water medium or pool 32. Such a perimetral antenna allows the reception of the remote signal from a place very distant from the site where the emergency occurs. It is to be noted that the preferred embodiment of this invention is based on the emission of UHF or VHF frequency signals.
Another embodiment of this alarm system is illustrated in Figures 6 and 7, and allows the detection and location of a user carrying the remote signal transmitter means 20 when said user is in the water medium, such as the sea, a river or a lake.
Figure 6 shows an arrangement by means of which the location of the user carrying the remote signal transmitter 20 can also be detected, especially when the water medium concerned is of a considerable size, such as the sea, a river, a lake, etc.
For this purpose, buoys 33, 34 and 35 arranged in the water medium 32, comprise repeater stations which emit signals which are received at the coast 36 by the receiver means 21 having a circuit which, in addition to emitting the alarm signal, also activates the monitor or computer interface 37 in which a respective alarm 33′, 34′ or 35′ is operated according to which of the buoys is emitting the signal.
The remote signal transmitter means 20 attached to the user's body effects a low-power transmission due to the reduced size thereof and its signal is transmitted at a higher intensity by the repeater station of the nearest buoy.
For the case in which the nearer repeater station is one of the buoys 33, 34 and 35, it will re-transmit the signal noticeably increasing its power and range and also at a different frequency.
Figure 7 shows a remote signal transmitter means 20 with a manually operable activating means 23 which activates said means.
By means of the antenna 42, it transmits the coded signal which is received by antenna 43 in the nearest buoy having a receiver means 22 similar to that shown in Figure 3.
This receiver means 22 is fed by a supply battery 45, which is in turn connected to a battery charger 46 for automatically recharging it.
When the receiver means 22 receives the coded signal, the transmitter-repeater 47 is activated and this, in turn, emits by means of antenna 48 a longer range signal which is received by antenna 49 of the receiver means 21 connected to the monitor device 37 of Figures 6 and 7. By means of the sound transducer and of the associated screen, the monitor device 37 indicates which one of the buoys is emitting the signal.
Among the different embodiments of this invention, the holder element 24 for the transmitter means 20 may be formed by a band 50 of fixed or adjustable length, whose free end includes a closure device formed by a tapered tongue 52 which in its upper part carries a lug 53 projecting above the upper surface of said tongue 52, the lug 53 being arranged to be in a retracted position with respect to the tongue 52 and comprising a locking system using a key which can be inserted by opening 54.
The system is completed at the other end 55 of the band 50 by a staple 56, which allows the insertion of the tongue 52 by pressing the lug 53 inside the tongue 52 until it passes the staple 56, the lug 53 being locked when returning to its initial position outside the tongue 52. Such a locking system prevents the accidental or unauthorised pressure on the lug 53, which can only be unlocked by the corresponding key, in the case when the user is a child.
The band 50 can be fixed at any part of the user's body, such as by the ankle, waist, arm or neck, and has the transmitter means 20 attached thereto with electrodes 30 of activating means 23 exposed so that, when in contact with water, the circuit is closed and the remote signal transmitter means 20 is activated.
Activating means 23 of the remote signal transmitter means 20 can have variations from the above described pattern; for example electrodes 30 can be covered by a water-proofing adhesive tape, so that the activating means 23 can be immersed in water and only activated when the user removes said adhesive tape and closes the circuit by thus bringing the electrodes 30 into contact with water.
Another alternative use of this invention, intended for swimmers, consists in placing the activating means 23 in a watertight case, with a switch operated by pressure through a flexible wall of said watertight case.
If desired, the remote transmitter 20 and receiver 21 may operate on audio frequency sound signals or ultrasonic signals.

Claims

An alarm system for detecting persons who accidentally fall into water and who may be in the water in an emergency situation that requires help, characterized by comprising a signal transmitter means (20) including an activating means (23) for actuating said transmitter means which is sensitive to a pre-determined condition, said transmitter means being attachable to the body of a user by removable means of attachment, and at least one receiver means (21) for receiving said transmitted signal and capable of identifying the signal and of controlling an alarm device disposed at a place where help is available.
A system according to claim 1, characterized in that the signal of the transmitter means is a coded signal and the receiver means for receiving said signal is capable of detecting said coded signal and of controlling a common alarm for said coded signals.
A system according to claim 1, characterized in that there are several of said transmitter means transmitting individual coded signals and said receiver means receiving said coded signals operates a different respective alarm for each coded signal.
A system according to any one of claims 1 to 3, characterized in that it comprises at least one means (33, 34, 35) for collecting and repeating said signal, disposed in a fixed location on the water medium, and at least one receiver means (21) for receiving said signal and capable of identifying said signal and of operating an alarm device.
A system according to any one of claims 1 to 3, characterized in that it further comprises at least two receiver means for receiving said signal and capable of identifying said signal and operating an alarm device, said receiver means being arranged on the land and spaced one from the other so as to cover a particular area of the adjacent water medium, said alarm device being connected to a means for locating the place from where the signal of the transmitter means is emitted as determined by the joint operation of said receiver means.
A system according to claim 4 or 5, characterized in that it comprises (i) at least one means for collecting and repeating said signal, and arranged in the water medium, (ii) at least two receiver means for receiving said repeated signal and capable of identifying said signal and of operating an alarm device, said receiver means being arranged on land and spaced one from the other so as to cover a particular area in the adjacent water medium, and said alarm device being connected to a means for locating the place from where the signal of the transmitter means is emitted as determined by the joint operation of said receiver means.
A system according to claims 4 and 6 taken together, characterized in that each means for collecting and repeating said signal is arranged on an anchored buoy, or a pile, or a wall.
A system according to either of claims 6 and 7, characterized in that the locating means is a radiogonometry device.
A system according to any one of claims 5 to 8, characterized in that the means for collecting and repeating the signal includes an amplifier of said signal.
A system according to any one of claims 1 to 9, characterized in that the alarm signal is of a progressive intensity.
A system according to any one of claims 1 to 10, characterized in that the alarm signal includes a control circuit that detects a temporary signal as distinct from a continuous signal.
A system according to any one of claims 1 to 11, characterized in that the activating means (23) is formed by a pair of exposed electrodes (30) which are interposed in the current feeding circuit of the transmitter means, said electrodes being optionally covered by a waterproof tape which can be manually removed.
A system according to any one of claims 1 to 11, characterized in that the activating means is a switch arranged in the current feeding circuit of the transmitter means, within a watertight housing and able to be operated from the outside.
A system according to any one of claims 1 to 13, characterized in that the transmitter means is a device transmitting high-frequency radio signals, preferably at VHF or UHF frequencies.
A system according to any one of claims 1 to 13, characterized in that the transmitter means is a device for transmitting audio-frequency signals.
A system according to any one of claims 1 to 13, characterized in that the transmitter means is a device for transmitting ultra-sound signals.
A system according to any one of claims 1 to 14, characterized in that said signal receiver means includes an antenna (31) perimetrally disposed with respect to the water medium.
A system according to any one of claims 1 to 17, characterized in that the means for removable attachment to the body of the user includes a safety lock system (53, 54, 56) which prevents the user from unlocking it by himself.