EP0653737A2

EP0653737A2 - A detection device

Info

Publication number: EP0653737A2
Application number: EP94307933A
Authority: EP
Inventors: Brian William Casey
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-11-15
Filing date: 1994-10-27
Publication date: 1995-05-17
Also published as: EP0653737A3; CA2134587A1; AU7779794A

Abstract

A detection device 10 includes a transmitter 14 which transmits a transmitted signal 16 of a first characteristic and, upon the occurrence of a predetermined event, causes a change in the characteristic of the transmitted signal 16. A receiver 18 is arranged remote from the transmitter 14, the receiver 18 being responsive to the transmitter 14. A discernible alarm 20 is connected to the receiver 18 to be activated by the receiver 18 when the receiver 18 receives the transmitted signal of changed characteristic or the receiver 18 fails to receive the transmitted signal 16.

Description

THIS INVENTION relates to a detection device. More particularly, the invention relates to a detection device for detecting the occurrence of a predetermined event.
According to the invention, there is provided a detection device for detecting the occurrence of a predetermined event, the detection device including
a transmitter means which transmits a transmitted signal of a first characteristic and, upon the occurrence of a predetermined event, causes a change in the characteristic of the transmitted signal;
a receiver means arranged remote from the transmitter means, the receiver means being responsive to the transmitter means; and
a discernible alarm means connected to the receiver means to be activated by the receiver means when the receiver means receives the transmitted signal of changed characteristic or the receiver means fails to receive the transmitted signal.
In this specification, the term "a change in the characteristic of the transmitted signal" is to be understood as including cessation of transmission of the signal.
The device may include a detecting unit to which the transmitter means is connected, the sensing means forming part of the detecting unit.
The detecting unit may further include a signal generating means for generating the transmitted signal. Then, the receiver means may include a detection circuit for detecting the transmitted signal.
In a preferred embodiment of the invention, the signal generating means is operable to generate a series of pulses on a substantially continuous basis.
Then, the detection circuit may include a missing pulse detector such that, in the absence of a predetermined number of pulses in the transmitted signal, the alarm means is activated by the receiving means. In addition, the signal generating means may be operable to generate, periodically, an identification code which is included in the transmitted signal.
Hence, it will be appreciated that, in use, the transmitter means transmits a signal comprising a string of pulses and, interspersed therein, the identification code. This signal is detected by the detection circuit of the receiving means and, while the signal is being received, the receiving means remains in a quiescent state and the alarm means is inactive.
The device may include a sensing means connected to the signal generating means. A particular application of the invention is the detection of the presence of liquid as defined below. In other words, the occurrence of the event is the presence of liquid. Then, the sensing means may detect the presence of the liquid.
In this specification, unless the context clearly indicates otherwise, the term "detecting the presence of a liquid" is to be understood in a broad sense as including the detection of flooding, the detection of leaks of liquids, the detection of the falling into a body of water or other liquid of a person or animal, or the like.
When the sensing means senses the presence of the liquid, a change of state of the sensing means occurs and this, in turn, causes the signal generating means to cease transmitting the pulses and the code.
Should the detection circuit of the receiver means fail to detect a number of pulses within a predetermined period of time, the receiving means causes the alarm means to be activated alerting a person in control of the receiving means to the presence of water.
An example of this application of the invention is the use thereof on a person or animal so that should such a person or animal fall into a body of water, another person is alerted thereto to enable action to be taken. Thus, the sensing means and the transmitter means (hereinafter referred to collectively as the "transmitting section" for ease of reference) are arranged in a housing, the housing, in use, being worn by the person or animal.
The transmitting section may thus include a power supply, driven by a battery, the power supply being incorporated within the housing.
The housing may, conveniently, include an attaching means for attaching it to the person or animal. The attaching means may thus include a switch means via which the power supply is connected to the battery. Typically, the attaching means may be a belt or strap having a buckle for fastening in position on the body of the person or animal. The switch means may be incorporated within the buckle so that, in order for the power supply to be activated, the buckle must be closed to close the switch means.
Further, the battery of the power supply may be rechargeable. Thus, the detection device may include a battery charging means for charging the battery.
Conveniently, the battery charging means may be incorporated in a container containing the receiving means. More particularly, the battery charging means or circuit may be incorporated within a power supply circuit of the receiving means.
To improve the versatility of the system, the container may be portable and may have the alarm means incorporated therein. In that case, the power supply circuit of the receiving means may also incorporate a battery supply.
In another embodiment of the invention, the signal generating means may, in normal circumstances, be inactive. Then, when the sensing means detects the presence of the liquid, and changes state, the signal generating means is activated to transmit a signal which is received by the receiving means.
The invention is now described by way of example with reference to the accompanying diagrammatic drawings.
In the drawings,

Figure 1 shows a schematic block diagram of a detection device, in accordance with a first embodiment of the invention, for detecting the occurrence of a predetermined event;
Figure 2 shows a circuit diagram of a detecting unit of the detection device of Figure 1;
Figure 3 shows a schematic block diagram of a detection device, in accordance with a second embodiment of the invention, for detecting the occurrence of a predetermined event;
Figure 4 shows a circuit diagram of a detecting unit of the detection device of Figure 3;
Figure 5 shows a circuit diagram of a transmitter section of a detection device, in accordance with yet a further embodiment of the invention, for detecting the occurrence of a predetermined event; and
Figure 6 shows a circuit diagram of a receiver section of the detection device in accordance with the further embodiment of the invention.

Referring firstly to Figures 1 and 2 of the drawings, a detection device, in accordance with a first embodiment of the invention, for detecting the occurrence of a predetermined event, more particularly the presence of a liquid and, specifically, water, is illustrated and is designated generally by the reference numeral 10. The detection device 10 is intended particularly to be worn by persons who are non-swimmers or animals so that an alarm signal is given should such a person or animal fall into a body of water such as a swimming pool. The invention will be described with reference to this application hereafter.
The detection device 10 comprises a detecting unit 12 which is responsive to water, when water impinges thereon, to emit a first signal. A transmitter means or transmitter 14 is connected to the detecting unit 12 and is responsive to said first signal to emit a transmitted signal 16 upon receipt of the first signal from the detecting unit 12.
The detection device 10 further includes a receiver means or receiver 18 which is responsive to the transmitted signal 16. The transmitter 14 and the receiver 18 are matched so that only that transmitter 14 associated with the receiver 18 will cause the receiver 18 to be activated. It will, however, be appreciated that, if desired, the detection device 10 could have a plurality of transmitters 14 which are matched to a particular receiver 18.
A discernible alarm means 20 is connected to the receiver 18. The discernible alarm means 20 comprises an audible alarm device such as a buzzer 22 and a visual alarm device such as a light emitting element 24.
As described above, the detection device 10 is intended particularly for use by non-swimmers. Thus, the detecting unit 12 and the transmitter 14 are contained in a housing 26 which can be worn in a suitable fashion by such a person. Hence, for example, the housing 26 could be worn watch-fashion by the person, as a necklace, or the like.
The detecting unit 12 comprises a sensing means 28 in the form of a pair of electrodes 30. The electrodes 30 are spaced from each other to define a gap between them. It will be appreciated that, when the gap between the electrodes is bridged by water, a change in resistance occurs. Hence, the electrodes 30 are connected to a triggering device 32 which is triggered when such a change in resistance occurs. The triggering device 32 comprises a thyristor 34 with one of the electrodes 30 being connected to a gate of the thyristor 34. An anode 38 of the thyristor 34 is connected to one end of a coil 40.1 of a switching means in the form of a relay 40. The other electrode 30 is connected to the other end of the coil 40.1. The relay 40 comprises normally open contacts 40.2 which are connected via connections 42 to the transmitter 14.
A cathode 44 of the thyristor 34 is connected to a variable potentiometer 46 which sets the sensitivity of the detecting unit 12.
The detecting unit 12 is powered via a battery 48. A reset switch 50, which is a normally closed switch, is connected in series with the battery 48.
In use, when a change of resistance occurs between the electrodes 30, such as when water impinges on the electrodes 30, the thyristor 34 is triggered causing current to flow in the coil 40.1 of the relay 40. When this occurs, the normally open contacts 40.2 close causing said first signal to be emitted to the transmitter 14. This in turn causes the transmitted signal 16 to be transmitted to the receiver 18, thereby activating the receiver 18. Activation of the receiver 18, in turn, causes activation of the alarm means 20 to alert a person to the fact that the wearer of the housing 26 has fallen into a swimming pool. To reset the device 10, the switch 50 is opened for a short period and the electrodes 30 dried.
Referring now to Figures 3 and 4 of the drawings, a detection device, in accordance with a second embodiment of the invention, for detecting the presence of water is illustrated. With reference to Figures 1 and 2 of the drawings, like reference numerals refer to like parts, unless otherwise specified.
In this embodiment of the invention, the contacts 40.2 of the relay 40 are normally closed contacts. Hence, the contacts 40.2 of the relay 40 remain closed and a first signal is sent along connections 42 to the transmitter 14. The transmitted signal 16 is in the form of a string of pulses. While the transmitter 14 is receiving the first signal from the detecting unit 12, the string of pulses 16 is emitted by the transmitter 14 to be received by the receiver.
The receiver 18 has a detection circuit 52 incorporated therein. While the string of pulses 16 is being received by the receiver 18, the receiver 18 is in a quiescent state and the alarm means 20 is inactive. If a pulse is not received by the missing pulse detector 52 within a predetermined period of time, the missing pulse detector 52 causes the receiver 18 to activate the alarm means 20.
Thus, in this embodiment of the invention, when water impinges on the electrodes, the thyristor 34 is triggered causing current to flow in the coil 40.1 of the relay 40. When this occurs, the contacts 40.2 of the relay 40 open thereby causing cessation of the signal from the detecting unit 12 to the transmitter 14. This in turn causes the transmitter 14 to cease emitting the string of pulses 16. The absence of the pulses 16 is detected by the missing pulse detector 52 causing the receiver 18 to activate the alarm means 20. Activation of the alarm means 20 alerts a person to the fact that the wearer of the housing 26 has fallen into the swimming pool.
Referring now to Figures 5 and 6 of the drawings, a transmitter section and a receiver section, respectively, of a detection device in accordance with yet a further embodiment of the invention is illustrated. Once again, with reference to the previous drawings, like reference numerals refer to like parts, unless otherwise specified.
The transmitter section, which is designated generally by the reference numeral 60, comprises the transmitter 14, the sensing means 28 comprising the pair of electrodes 30 and the detecting unit 12.
In this embodiment of the invention, the detecting unit 12 is a solid state device. Typically, the detecting unit 12 comprises an embedded micro-controller PROM chip 62. The chip 62 is programmed to transmit a series of pulses through the transmitter 14 every few seconds. After a predetermined number of pulses have been sent a timer of the chip 62 initiates the transmission of a unique identification signal via the transmitter 14. The identification code emitted by the chip 62 is governed by a series of inputs in the form of switches 64 to the chip 62.
The transmitter section 14 includes a stabiliser in the form of a surface acoustic wave resonator 66 for smoothing oscillations of a transistor 68 driving an antenna loop 67 of the transmitter 14. The resonator 66 also serves to reduce frequency drift of the transmitter 14.
As indicated above, the transmitter section 60 is self-contained within the housing 26 and includes a power supply 70. The power supply 70 is driven via a battery which is received in a battery compartment 72. The power supply provides an unregulated 12 volt output 74 and, via a regulator 76, a regulated 5 volt output 78.
The battery used in the transmitter section 60 is a re-chargeable battery.
A switch 80 is located between the battery compartment 72 and the outputs 74 and 78. The switch 80 is a normally open switch and is closed when buckles of a strap (not shown) carrying the housing 26 are closed, in use.
Referring now to Figure 6 of the drawings, the receiver section of the detection device 10 is illustrated and is designated generally by the reference numeral 90. The receiver section 90 incorporates the receiver 18, the alarm means 20 and a power supply circuit 92.
The receiver 18 also comprises an embedded micro-controller PROM chip 94. The chip 94 is similarly configured to the chip 62 of the detecting unit 12. The chip 94 is responsive to the same code as that of the chip 62 via a set of similarly configured switches 96. Thus, the chip 94 of the receiver 18 is responsive to the series of pulses and the identification code emitted by the chip 62 of the detecting unit 12 and which is transmitted via the transmitter 14.
In this embodiment of the invention, the alarm means 20 comprises a buzzer 98 driven via a drive transistor 100 and an indicating means 102 driven by a transistor 104.
The indicating means 102 is in the form of a light emitting diode (LED). The LED 102 is connected via the transistor 104 to an output of the chip 94 and is operable, when the detection device 10 is operational to flash while the signal is being received so that a person can ascertain that the detection device 10 is operating. In addition, if desired by closing a switch 106, the buzzer can be caused to emit a low intensity sound while the receiver 18 is receiving signals from the transmitter 14.
The power supply circuit 92 of the receiving section 90 comprises a battery charging circuit 108. The battery charging circuit 108 is used for charging a battery of the transmitter section 60. Thus, conveniently, a container, represented schematically by line 110 containing the receiver section 90 may have a seat defining formation therein in which the transmitter section 60 is receivable. A set of contacts 112, engaged by the battery of the transmitter section 60, may be arranged in the seat defining formation of the container 110. Hence, it will be appreciated that, when the detection device 10 not in use, the transmitter section 60 is placed in the seat defining formation of the housing of the container 110 to enable a battery of the transmitter section 60 to be re-charged.
Conveniently, the container 110 can also be portable. To cater for this, the power supply circuit also includes a battery 114. The power supply circuit 92 includes a battery monitoring circuit 116 for monitoring the condition of the battery 114. When the voltage of the battery 114 drops below a predetermined, threshold value, an appropriate signal is sent along line 118 to the chip 94 to cause the alarm 20 to be activated.
Once again, with this embodiment of the invention, should the sensing means 28 detect the presence of water, a change of resistance occurs across the electrodes 30 causing the appropriate signal to be input into the chip 62 of the detecting unit 12. When this occurs, the chip 62 ceases the transmission of the pulses and the code. When this occurs, the chip 94 of the receiver 18, or if it failed to detect pulses for a predetermined period of time, causes a signal to be output to activate the alarm 20. The buzzer 98 is activated alerting the person in control of the receiver section 90 of the device 10.
A further advantage of the two latter embodiments of the invention is that it serves to assist a person to keep a check on another person. Thus, for example, a mother can keep a check on her toddler by attaching the housing 26 to the toddler. Then, if the toddler moves out of range of the receiver 18, this will cause the receiver to activate the alarm means 20. It will be appreciated that this is also especially advantageous for use by infirm people or people of reduced mental capacity.
Hence, with the provision of the detection device 10 in accordance with the invention, rapid remedial actions is facilitated where a non-swimmer or animal has fallen into a body of water or person moves out of range of the receiver 18.

Claims

A detection device for detecting the occurrence of a predetermined event, the detection device including
a transmitter means which transmits a transmitted signal of a first characteristic and, upon the occurrence of a predetermined event, causes a change in the characteristic of the transmitted signal;
a receiver means arranged remote from the transmitter means, the receiver means being responsive to the transmitter means; and
a discernible alarm means connected to the receiver means to be activated by the receiver means when the receiver means receives the transmitted signal of changed characteristic or the receiver means fails to receive the transmitted signal.
The device as claimed in Claim 1 which includes a detecting unit to which the transmitter means is connected.
The device as claimed in Claim 2 in which the detecting unit includes a signal generating means for generating the transmitted signal.
The device as claimed in Claim 3 in which the receiving means includes a detection circuit for detecting the transmitted signal.
The device as claimed in Claim 4 in which the signal generating means is operable to generate a series of pulses.
The device as claimed in Claim 5 in which the detection circuit includes a missing pulse detector such that, in the absence of a predetermined number of pulses in the transmitted signal, the alarm means is activated by the receiving means.
The device as claimed in Claim 5 or Claim 6 in which the signal generating means is operable to generate, periodically, an identification code which is included in the transmitted signal.
The device as claimed in any one of Claims 3 to 7 inclusive which includes a sensing means connected to the signal generating means, the sensing means detecting the presence of the liquid and the sensing means controlling operation of the signal generating means.
The device as claimed in any one of the preceding claims in which the sensing means and the transmitter means are arranged in a housing, the housing, in use, being worn by a person or animal.
The device as claimed in Claim 9 in which a power supply, driven by a battery, is incorporated in the housing.
The device as claimed in Claim 10 in which the housing includes an attaching means for attaching it to the person or animal, the attaching means including a switch means via which the power supply is connected to the battery.
The device as claimed in Claim 11 in which the battery of the power supply is re-chargeable.
The device as claimed in Claim 12 which includes a battery charging means for charging the battery.
The device as claimed in Claim 13 in which the battery charging means is incorporated in a container containing the receiving means.
The device as claimed in Claim 14 in which the container is portable and the alarm means is also contained in the container.