WO2002057764A2

WO2002057764A2 - Means for initiating a self-test

Info

Publication number: WO2002057764A2
Application number: PCT/EP2002/000369
Authority: WO
Inventors: Jonathan Charles Wheeler
Original assignee: Crowcon Detection Instruments Ltd
Priority date: 2001-01-19
Filing date: 2002-01-15
Publication date: 2002-07-25
Also published as: GB0101493D0; WO2002057764A3; AU2002237270A1

Abstract

Means are provided for initiating a self-test of a device comprising a transducer sensitive to predetermined vibrations which provides a signal, when subject to the predetermined vibrations, that activates a means which indicates that the device is operational, the device may be a personal gas detector and the predetermined vibrations may be those caused by knocking the device against a hard surface two or more times.

Description

MEANS FOR INITIATING A SELF-TEST

The present invention relates to the provision of an improved self-test mechanism, which is particularly useful to ensure that devices, particularly safety devices are operational. The invention is especially concerned with personal safety devices that are used in an industrial environment in particular it is concerned with personal gas detectors. Such safety devices are well known and are used in hazardous environments such as industrial plant, mines, oilrigs and the like. It is common practice that they are tested before entry into the potentially hazardous environment to ensure they are operational.

In order for devices such as personal gas detectors to serve their purpose, they must, of course, be operational. It is therefore important that periodically they are checked to ensure that they are working. Currently this is accomplished by activating a self-test switch such as by depressing a self-test button. This however suffers from the difficulty that the switch can be difficult to operate particularly when, as is common, the operator is wearing gloves for safety. The current testing systems also rely on switch mechanisms with contacts which can become worn and unreliable.

The present invention aims to overcome these difficulties.

The present invention therefore provides a means for initiating a self-test of a device comprising a transducer sensitive to predetermined vibrations which provides a signal when subject to the predetermined vibrations that activates a means which indicates that the device is operational.

It is preferred that the transducer is located inside the casing of the device and is an audio transducer and that the predetermined vibrations are due to sound such as that emitted by knocking the device against a hard surface or hitting the device with a hard object. The transducer produces a signal when it is subject to the predetermined vibrations and the signal passes to a microprocessor which is programmed to be sensitive to certain predetermined vibrations. The software is programmed to determine the number of vibrations that initiate the self-test, for example the test may be initiated if the device is knocked twice in quick succession. In this way false triggering due to accidentally knocking or dropping of the device is avoided. Where the device is a warning device, the means which indicates that the device is operational is typically activation of the warning signal that is emitted when the device detects a hazardous situation.

An example of where the present invention is particularly useful is with personal gas detectors which are used to warn personnel of the presence of toxic gases or the absence of oxygen in the atmosphere, although it may be used with various other devices such as mobile phones, pagers and the like. Personal gas detectors are frequently worn by the personnel in industrial plant, in mines, on oilrigs and in other activities where hazardous gases may be emitted and/or where there is a risk that oxygen supplies may become depleted. The detector is body worn, normally on the breast pocket of industrial overalls, boiler suits and the like. Periodically the gas detector must be checked to see that it is still working.

Historically this check has been made by pressing a 'self-test' button. However, when the present invention is used, instead of pressing a 'self-test' button, a transducer inside the gas detector senses vibration when the detector is knocked against a hard surface or the detector is hit with a hard object. The transducer used is preferably the same electromagnetic sounder that is used to provide the audible warning when a gas hazard is detected. When the predetermined vibration is sensed by the transducer the transducer provides an electric signal which is conveyed to the microprocessor which then initiates the self-test. This self-test may be used to measure the battery voltage, activation of warning lights and sounders to ensure that everything is functional. In order to prevent false triggering when the gas detector is accidentally knocked, the self-test mechanism may be programmed to react when the detector is knocked twice (or more times) in a predetermined manner such as in quick succession (for example, less than 1 second between knocks). In this way only deliberate multiple, preferably double taps will initiate the self-test.

The invention therefore provides a system which is easier to activate to cause a self-test in an industrial environment with gloved hands. In addition the self-test is more reliable due to the absence of switches and the absence of any need to establish electric contacts. Furthermore the lifetime problems that are associated with self-test mechanisms involving switches in harsh environments are reduced or avoided.

Claims

1. A means for initiating a self-test of a device comprising a transducer sensitive to predetermined vibrations, which provides a signal when subject to the predetermined vibrations such that the signal activates a means which indicates that the device is operational.

2. A means according to Claim 1 in which the signal from the transducer passes to a microprocessor which is programmed according to the desired self-test procedure.

3. A means according to Claim 1 or Claim 2 in which the predetermined vibrations are generated by knocking the device against a hard surface a plurality of times.

4. A means according to Claim 2 in which the predetermined vibrations are generated by knocking the device against a hard surface two times.

5. A means according to any of the preceding claims in which the device is a personal gas detector.

6. A means according to Claim 5 in which the means which indicates that the device is operational is activation of the warning signal that is emitted when the device detects a hazardous situation.