GB2291243A

GB2291243A - Rain alarm with transmitter

Info

Publication number: GB2291243A
Application number: GB9413460A
Authority: GB
Inventors: Joan Ellen Shippen
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-07-05
Filing date: 1994-07-05
Publication date: 1996-01-17
Anticipated expiration: 2014-07-05
Also published as: GB2291243B; GB9413460D0

Abstract

The rain alarm comprises a transmitter unit having a hook along its upper edge for attaching it to a washing line W. The transmitter unit houses a transducer 12, a surface 13 of which is exposed when the rain alarm is in use. The transducer 12 is arranged to change its impedance when the exposed surface 13 gets wet. A sensing circuit measures the impedance of the transducer and, in the event of a change, outputs a control signal to activate a radio or ultrasonic transmitter mounted in the transmitter unit 12. The radio transmitter sends a coded signal to a remote receiver unit (not shown) and triggers an audible alarm, such that the user is alerted to the fact that it is raining. <IMAGE>

Description

Rain Alarm This invention relates to a rain alarm.

It has been proposed to provide an alarm which gives an audible indication that it is raining, so that washing etc left outdoors can be brought in. One such rain alarm comprises a transducer having plurality of exposed conductive tracks connected to a sensing circuit. The unit is mounted outdoors and, as rain falls, droplets of water collect on the transducer and bridges the conductive tracks. The sensing circuit senses a change in the electrical resistance across the tracks and activates an audible alarm, which alerts a person indoors.

A disadvantage of this type of rain alarm is that it is difficult to hear the alarm sounding from indoors. In order to overcome this problem, it is usual to mount the alarm near a window so that the alarm can be heard. However, it is undesirable to mount the alarm close to a building in this way because the building may provide shelter, and thus the alarm may fail to detect that it is raining.

I have now devised a rain alarm which alleviates the above-mentioned problems.

In accordance with this invention there is provided a rain alarm, comprising a transducer for detecting the occurrence of rain, and sensing means connected to the transducer and arranged to activate a remote warning device when rain is detected.

Thus, because the warning device is located remote from the transducer which senses the rain, the transducer can be positioned in an exposed place whilst the warning device can be located indoors to alert the user.

Preferably the rain alarm comprises a transmitter unit which houses the transducer and sensing means, and a receiver unit which houses the warning device, the transritter unit further comprising transmitting means for transmitting a wireless signal to trigger the warning device in the receiver unit.

The transmittiny means may be arranged to transmit radio, infra-red or ultra-sonic signals te trigger the warning device in the receiver unit.

Preferably the receiver unit comprises an audible warning device.

Preferably the transmitting unit comprises means for attaching it to a washing line, so that the transducer is mounted adjacent to the washing being protected.

Preferably the transducer comprises an element which changes an electrical characteristic thereof (e.g. its impedance, particularly its resistance) when an exposed surface thereof gets wet.

Preferably the exposed transducer surface is inclined, so that rain water will drain fro this surface and not collect thereon.

Preferably the transducer is mounted on a hinged member, so that the transducer can be oriented at a selected angle to catch the rain.

An embodiment of this invention will now be described by way of example only, and with reference to the accompanying drawings, in which: FIGURE 1 is a perspective view of a transmitter unit of a rain alarm in accordance with this invention; and FIGURE 2 is a perspective vie of a receiver unit of the rain alarm.

Referring to Figure 1 of the drawings, there is shown the transmitter unit of a rain alarm, the transmitter unit comprising a plastics housing 10 having a hook along its upper edge for attaching the transmitter unit to a washing line W.

A flap 11 hinged to the housing 10 carries a flat transducer 12 for detectiny rain water.

The transducer 12 comprises a flexible sheet plastics substrate 13, on which two isolated conductive tracks 14,15 are etched. Each of the tracks 14,15 comprises a plurality of parallel, horizontal branches which are interleaved with the correspondiny branches of the other track. The tracks 14,15 are connected to a sensing circuit r;Our,ted inside the housing 10 via a flexible web 16 cf the plastics substrate 13.

The sensing circuit reassures the electrical resistance across the isolated tracks lye15. The resistance is normally in the order cf several megchrs, but when it rains, droplets of rain collect on the transducer and bridge the tracks 14,15, thereby reducing the resistance to several k.l0hms. This change in the resistance is sensed by the sensing circuit, which outputs a control signal to activate a radio transmitter mounted in the housing 10. A battery compartment 17 is provided on the housing 10, and the transmitter unit is activated by hinging the flap 11 downwards away from its outof-use position, in which it lies flat against the front wall of the housing 10.

Referring to Figure 2 of the drawings, the receiver unit comprises a plastics housing 20 provided with a clip (not shown) for attaching the unit to an article of clothing. The receiver unit houses a radio receiver which triggers an audible alarm device 21 when a coded signal is received from the transmitter unit. An ON/OFF switch 22 is provided on the front of the housing 20 and the housing includes a battery compartment 23.

In use, the transmitter unit is activated by hinging the flap 11 outwardly from the housing 10 and then downwards, and the unit is then hooked over a washing line as shown in Figure 1. The flap 11 is angled downwardly, so that any rain which falls onto the transducer 12 drips off the free edge of the flap 11, and thus does not collect on the transducer. The receiver unit is switched on and carried by the user indoors.

If rain falls near the washing line, the transmitter unit transmits a coded radio signal to trigger the audible alarm 21 on the receiver unit, so that the user is alerted to the fact that it is raining and can fetch indoors the washing on the line.

Claims

1) A rain alarm, comprising a transducer for detecting the occurrence of rain, and sensing means connected to the transducer and arranged to activate a remote warning device when rain is detected.

2) A rain alarm as claimed in claim 1, comprising a transmitter unit which houses the transducer and sensing means, and a receiver unit which houses the warning device said transmitter unit further comprising transmitting means for transmitting a wireless signal to trigger the warning device in said receiver unit.

3) A rain alarm as claimed in claim 2, wherein the transmitting means is arranged to transmit radio, infra-red or ultra-sonic signals to trigger the warning device in the receiver unit.

4) A rain alarm as claimed in claims 2 or 3, wherein the receiver unit comprises an audible warning device.

5) A rain alarm as claimed in any of claims 2 to 4, wherein the transmitting unit comprises means for attaching it to a washing line.

6) A rain alarm as claimed in any preceding claim, wherein the transducer comprises an element which changes an electrical characteristic thereof when an exposed surface thereof gets wet.

7) A rain alarm as claimed in claim 6, wherein the transducer comprises an element which changes its impedance when an exposed surface thereof gets wet.

8) A rain alarm as claimed in claims 6 or 7, wherein the exposed transducer surface is inclined.

9) A rain alarm as claimed in any preceding claim, wherein the transducer is mounted on a hinged member, such that the transducer can be oriented at a selected angle.

10) A rain alarm substantially as herein described, with reference to the accompanying drawings.