GB2219679A - Detector for use in connection with a nappy - Google Patents

Abstract

The detector comprises a sensor 16 adapted in use for location in or on the nappy, an indicator 17, and a driver circuit 19 for the indicator. The indicator is energised to provide a warning signal in response to the sensor detecting when the nappy gets wet. The sensor and indicator may be provided in separate units connected together by a radio link. <IMAGE>

Description

DETECTOR FOR USE IN CONNECTION WITH A NAPPY The present invention relates to a detector for use in connection with a nappy.

In the broadest aspic., the ..;c, ivn provides a detector for use in connection with a nappy, said detector comprising a sensor adapted in use for location in or on a said nappy to provide an electrical signal when a said nappy becomes wet, an indicator, and a driver circuit for energising the indicator in response to an electrical signal received from the sensor.

In a preferred aspect, the invention provides a detector for use in connection with a nappy, said detector comprising a first unit, which includes a sensor and a transmitter, adapted for location in or on a said nappy to provide a radio signal when a said nappy becomes wet, and a separate second unit, which includes a receiver and an indicator, for providing a warning signal in response to the radio signal received from the first unit.

Other, prefered and/or optional features of the invention will be apparent from the following description and the accompanying claims 2 to 5 inclusive.

The invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view showing a first embodiment of a detector in accordance with the invention, located on a nappy, Figure 2 is a circuit diagram of the detector of Figure 1; and Figure 3 is a circuit diagram of a second embodiment of a detector in accordance with the invention.

Referring now to Figure 1 of the drawings, a detector 10 shown therein comprises a casing 11 having an integral clip 12 for attaching the detector 10 to a nappy 13 worn by a child 14.

Figure 2 shows an electrical circuit 15 of the detector 10. The circuit comprises a sensor in the form of a switch 16, a piezo-electric buzzer 17, an oscillator 18 for the piezo-electric buzzer 17, and a driver circuit 19 provided between the sensor switch 16 and the oscillator 18. The sensor switch 16 includes a printed circuit board 20 bearing a pair of switch terminals in the form of two spiral conducting tracks 21 arranged in closely spaced apart relationship.

The driver circuit 19 comprises a series connection of a d.c. voltage supply V and an on-off switch SW between a circuit node Vcc and ground E, two resistors R1 and R2, and two NPN bipolar transistors TR1 and TR2. The transistor TR1 ha its collector connected to the circuit node Vcc, and its base and emitter connected to the ground E through resistors R1 and R2, respectively. The emitter of the transistor TR1 is connected to the ground E through the base-emitter path of the transistor TR2.

The sensor switch 16 is connected across the circuit node Vcc and the base of the transistor TR1, and the oscillator 18 is connected across the circuit node Vcc and the collector of the transistor TR2.

The detector circuit 15 is contained in the casing 11, except the sensor switch 16 which is mounted on the outside of the casing 11 and connected to the circuit 15 by a pair of wires 22. In use, the casing 11 is located on the nappy 13 by the clip 12, and the sensor switch 16 is placed inside the happy 13. The on-off switch SW is closed to enable the operation of the detector circuit 15.

When the child 14 urinates, the urine disperses and eventually reaches the two conducting tracks 21 on the printed circuit board 20 of the sensor switch 16. The conducting tracks 21 are arranged sufficiently close together that the urine will create a low resistance path between the tracks 21. When this occurs, the two transistors TR1 and TR2 will turn on to connect the oscillator lo across the voltage supply V. The oscillator 18 provides an a.c. signal to operate the piezo-electric buzzer 17 to give an audible warning signal indicating that the chIld 14 has a wet nappy 13 which requires changing.

The sensor switch 16 and the wires 22 are cleaned and dried before the detector 10 is used again. It is envisaged that the detector 10 could be miniaturised and located inside a disposable nappy for disposal with the nappy after use.

Figure 3 shows a detector circuit 23 of a second embodiment of the invention, with like parts identified by the same numerals. The detector circuit 23 includes separate first and second parts 24 and 25. The first part 24 includes a radio transmitter 26, and the second part 25 includes a radio receiver 27.

The first part 24 also includes the sensor switch 16 and the driver circuit 19, the transmitter 26 being connected to the driver circuit 19 instead of the oscillator 18 of Figure 2. The oscillator 18 and the piezo-electric buzzer 17 are also included in the second part 25. The first and second parts 24 and 25 are contained in separate casings (not shown).

The detector circuit 23 operates in a manner very similar to that of the detector circuit 15. The transmitter 26 provides a radio signal in response to the operation of the sensor switch 16. The receiver 27 receives the radio signal and operates the oscillator 18 and in turn the piezo-electric buzzer 17 to give an audible warning signal.

In use, the casing containing the first part 24 is attached to a nappy, and the sensor switch 16 is placed in the nappy in a manner similar to that of the detector 10 of Figure 1. The casing containing the second part 25 is carried by a person looking after a child wearing the nappy. This arrangement provides a convenient way of remote monitoring the condition of the nappy without disturbing the child, particularly when the child is asleep.

Various modifications and/or alterations of the invention will be apparent to persons skilled in the art without departing from the scope of the invention as defined by the accompanying claims.

Claims (8)

1. A detector for use in connection with a nappy, comprising a sensor adapted in use for location in or on a said nappy to provide an electrical signal when -a said nappy gets wet, an indicator, and a driver circuit for energising the indicator in response to an electrical signal received from the sensor.

2. A detector as claimed in claim 1, further comprising a radio transmitter connected to the sensor, and a separate radio receiver which is co-operable with the transmitter to operate the indicator.

3. A detector as claimed in claim 1 or claim 2, wherein the sensor includes a printed circuit board bearing two electrical contacts disposed adjacent to each other.

4. A detector as claimed in any one of claims 1 to 3, wherein the indicator provides an audible warning signal.

5. A detector as claimed in claim 4, wherein the indicator includes a piezo-electric buzzer.

6. A detector for use in connection with a nappy, comprising a first unit, which includes a sensor and a transmitter, adapted for location in or on a said nappy to provide a radio signal when a said nappy gets wet, and a separate second unit, which includes a receiver and an indicator, for providing a warning signal in response to a radio signal received from the first unit.

7. A detector for use in connection with a nappy, substantially as hereinbefore described with reference to Figures 1 and 2, or Figure 3 of the accompanying drawings.

8. A nappy provided with a detector as claimed in any one of the preceding claims.