GB2045492A

GB2045492A - Alarm device

Info

Publication number: GB2045492A
Application number: GB7909250A
Authority: GB
Original assignee: BALMORE ENG Ltd
Current assignee: BALMORE ENG Ltd
Priority date: 1979-03-15
Filing date: 1979-03-15
Publication date: 1980-10-29

Abstract

An alarm device for carrying on the person to provide an alarm indicating that the carrier has collapsed. The alarm device comprises a mercury switch (S) arranged to change from a first condition to a second condition when moved from a substantially vertical attitude through an angle which is greater than a specified angle, time delay means (C, R) connected to the switch (S) and adapted to operate after a specified time interval during which the switch (S) is continuously in said second condition, and alarm means (A) connected to the time delay means (C, R) and adapted to provide an alarm signal after said specified time interval has elapsed. <IMAGE>

Description

SPECIFICATION Alarm device This invention is concerned with improvements in or relating to alarm devices and is specifically concerned with personal alarm devices.

It is believed that there is a requirement for an alarm device which will provide an alarm indicating that a carrier of the device has collapsed and is in a condition which requires assistance. For example, personnel who are required to work in hazardous conditions, such as firemen, who may be overcome by fumes or rendered unconscious by falling timbers or masonery, would benefit from an alarm device which gave a warning of their condition. A further example of the use to which such an alarm device can be put is in the care and observation of the elderly or handicapped.

The present invention provides an alarm device which comprises switch means arranged to change from a first condition to a second condition when moved from a vertical or substantially vertical attitude through an angle which is greater than a specified angle, time delay means connected to the switch means and arranged to operate after a specified time interval during which said switch means is continuously in said second condition, alarm means connected to the time delay means and arranged to emit an alarm signal after said specified time interval has elapsed, and means whereby power can be connected to the device.

In a device as set forth in the last preceding paragraph a switch means is preferably a mercury switch which may in its first condition either be normally closed or normally open. The mercury switch preferably comprises a housing having a recess containing the mercury when the switch is in said first condition with one contact extending into the recess. For a switch which is normally closed in its first condition, a second contact will extend into the mercury from a location such that when the switch is tilted through an angle greater than said specified angle, a circuit through the mercury between the two contacts is broken. In a 'normally open' switch the arrangement is such that the second contact will touch the mercury when the switch is tilted beyond the specified angle while the mecury is still in electrial contact with the first contact.The housing is preferably made of glass and when incorporated in an alarm device according to the invention can be potted, i.e. encapsulated in a protective medium, for example epoxy resin.

The time delay means may be provided by any suitable time delay circuit. Preferably the time delay means can be adjustable to provide a time delay of for example ten seconds to two minutes.

The time delay circuit may be connected with the switch means via a trigger provided by an l.C. to which the alarm is also connected.

The alarm device may provide an audio and/or visual and/or r.f. output. When an r/f output is included, this may provide a coded signal identifying the device and thus the wearer. The audio alarm may be a buzzer, a bell or provide an intermittent audio output.

The visual alarm may be provided by a continuous or flashing light source.

An alarm device according to the invention is designed to be worn on or in a pocket or on a waistbelt although as will be appreciated the location of the device may be altered according to the conditions of use. Furthermore the device may also incorporate means whereby it may be activated independently of the condition of the mercury switch.

As will be understood from the foregoing, and will be even more clearly appreciated from the following description of two embodiments of the invention, an alarm device according to the invention would be of considerable benefit to any person who is either incapacitated by fumes or by injury or who has fallen over and is unable to rise. The delay circuit prevents the device from being activated by the wearer simply bending over to pick up an implement and yet provides a sufficiently short period of time to allow recovery of the wearer, in the event of an accient, as quickly as possible.

There now follows a detailed description which is to be read with reference to the accompanying drawings of a switch for use in a device according to the invention, and of two circuit diagrams of devices according to the invention. It is to be clearly understood that these two devices have been selected for description to illustrate the invention by way of example and not by way of limitation.

In the accompanying drawings: Figure 1 is a schematic sectional view of a mercury switch for use in a device according to the invention, with the switch shown in its upright, first condition; Figure 2 is a schematic sectional view of the mercury switch of Fig. 1 shown in a tilted second condition; Figure 3 is a circuit diagram of a first alarm device according to the invention; and Figure 4 is a circuit diagram of a second alarm device according to the invention.

Referring firstly to Figs. 1 and 2, the illustrated switch shown therein comprises a bellshaped glass housing 10 having a recess 1 2 in a base portion thereof for accommodating a single globule of mercury 1 4. A first electrical contact 1 6 extends upwardly into the recess 1 2 and a second electrical contact 1 8 extends downwardly from the top of the housing into the mercury globule so that in the position shown there is an electrical contact via the globule between the two contacts 1 6 and 1 8.

When the switch is tilted, the surface tension of the mercury and the shape of the recess will cause it to remain in the recess until the specified angle is exceeded as in Fig. 2, at which point the mercury will flow from the recess and break the electrical connection between the first and second contacts.

The switch shown in Figs. 1 and 2 is incorporated at S in either one of the circuits shown in Figs. 3 and 4, each of which employs as l.C.1, a 555 timer, the time delay being provided by the series connected capacitor C and resistor R.

Referring specifically to Fig. 3, the circuit shown therein comprises terminals a, b whereby a battery can be connected thereto, terminal a being connected to one contact of the switch S, to contact '1' of l.C.1, to capacitor C1 and to the capacitor C. The other contact of the switch S is connected via a resistor R1 to contact '2' of l.C.I. The capacitor C1 is connected to contact '5' of l.C.1 while capacitor C is connected to contacts '6' and '7' of l.C.1 and to the resistor R.

Terminal b is connected via an on/off switch S1 to the alarm means A which is in parallel with a diode D1 and connected via a diode D2 with contact '3' of l.C.1. Contacts '4' and 8 of l.C. 1 are connected via the switch S1 with terminal b, as is the resistor R.

Referring now to Fig. 4, the circuit shown therein is similar to that of Fig. 3 with the exception that the alarm means A of the latter circuit is replaced by a relay RL connected by its contacts '1' and '4' between the switch S1 and the diode D2, contacts '1' and '4' being connected to the coil of the relay. Contacts '2' and '7' of relay RL are connected in an auxiliary circuit including a first switch M of the relay, an auxiliary battery B1 and audible alarm means A. Contacts '3' and '6' of relay RL are connected in a second auxiliary circuit including a second switch N of the relay, auxiliary battery B2 and an r.f. transmitter T.

The switch S is designed to open when tilted at or beyond 40 from the vertical and the time delay components are selected optimumly to provide a delay of approximately 20 seconds, both of which values will allow a wearer of the device to pick-up tools and to work normally without the alarm being actuated each time that he bends down.

Claims

1. An alarm device comprising switch means arranged to change from a first condition to a second condition when moved from a vertical or substantially vertical attitude through an angle which is greater than a specified angle, time delay means connected to the switch means and arranged to operate after a specified time interval during which said switch means is continuously in said second condition, alarm means connected to the time delay means and arranged to emit an alarm signal after said specified time interval has elapsed, and means whereby power can be connected to the device.

2. An alarm device according to claim 1, wherein said switch means is a mercury switch.

3. An alarm device according to claim 2, wherein said mercury switch comprises a housing having a recess therein in which the mercury is contained when the switch is in said first condition.

4. An alarm device according to claim 3, wherein said mercury switch is normally closed in said first condition and comprises two electrical contacts which are so arranged as to be both in electrical contact with the mercury in said recess and hence with each other, only when the switch is in the first condition.

5. An alarm device according to claim 3, wherein said mercury switch is normally open in said first condition and comprises two electrical contacts one of which is in electrical contact with the mercury in said recess in both the first and second condition of the switch and the other of which only makes electrical contact with the mercury when the switch is in said second condition.

6. An alarm device according to claim 3, 4 or 5, wherein said housing is of glass and is encapsulated in a protective medium.

7. An alarm device according to any one of the preceding claims wherein said time delay means comprises a time delay circuit which is adjustable to provide a required time delay.

8. An alarm device according to claim 7, wherein said time delay means is adjustable to provide a time delay of from ten seconds to two minutes.

9. An alarm device according to claim 7 or 8, wherein said time delay circuit is connected with the switch means via a trigger to which the alarm means is also connected.

10. An alarm device according to any one of the preceding claims, wherein said alarm means is adapted to provide an audio and/or visual and/or r.f. output.

11. An alarm device according to claim 10, wherein said alarm means is adapted to provide an r.f. output comprising a coded signal identifying the device and thus a user thereof.

1 2. An alarm device according to any one of the preceding claims, having means whereby it can be secured to the body or clothing of a user so that said switch means will be in the first condition when the user is standing upright.

1 3. An alarm device according to any one of the preceding claims, wherein overide means is provided whereby said alarm may be actuated independently of the condition of said switch means.

14. An alarm device substantially as herein described with reference to the accompanying drawings.