GB2067051A

GB2067051A - Portable emergency transmitter

Info

Publication number: GB2067051A
Application number: GB8040790A
Authority: GB
Original assignee: IMPAMA ANSTALT
Current assignee: IMPAMA ANSTALT
Priority date: 1979-12-28
Filing date: 1980-12-19
Publication date: 1981-07-15
Also published as: IT8026788A0; SE8008623L; NO803844L; DE3047231A1; ES8201752A1; ES498073A0; IT1149823B; FR2475259A1

Abstract

An emergency transmitter comprises a housing in which a power source 17 and an emergency call generator 18 are arranged. The emergency call generator 18 may be connected to the power source 17 and thereby be energised to transmit an emergency call signal either by a hand switch assembly 22 or automatically by an inclination switch 24 associated to a delay circuit. The inclination switch 24 is a normally open contact which closes as soon as the housing deviates or is tilted out of its normal position. When closed, the inclination switch 24 energises without delay an acoustical generator 29 in order to announce the forthcoming actuation of the emergency call generator. <IMAGE>

Description

SPECIFICATION Portable emergency transmitter The invention relates to emergency equipment and more particularly to an emergency transmitter. The invention also relates to an inclination switch, particularly for such portable emergency transmitters.

Emergency transmitters are normally used by persons going to lonesome and dangerous places in order to be able to call for help in case of emergency. Such emergency transmitters may be used by skiers, by climbers, by explorers and also by miners.

Prior art emergency transmitters comprise, apart from the hand operated switch assembly, which enables the intentional switchingon of an emergency call generator, also switching means responsive to extreme acceleration or deceleration for automatically switching on the emergency call generator. It is a proven fact, however, that not every emergency situation may be intentionally realised or detected by means of an accelerometric element.

The invention seeks to provide an improved emergency transmitter, in which, apart from the hand operated switch means, additional switch means are provided which are automatically responsive to another parameter for switching on the emergency call generator.

According to the invention there is provided a portable emergency transmitter comprising a housing, a power source within said housing, an emergency call generator within said housing, a hand switch assembly for connecting said emergency call generator to said power source, additional switch means responsive to variations of position of said housing, a delay circuit series connected to said additional switch means, said additional switch means and said delay circuit being adapted for delayed switching-on said emergency call generator in response to a variation of position of said housing.

The operation of the emergency transmitter according to the invention is therefore based on the knowledge, proved by facts, that in practically all emergency situations the bearer of the emergency transmitter is in a physical position differing from the normal position or bearing.

The emergency call generator may be an acoustic generator, which has, however, a relatively small transmission range and which, under certain circumstances, may be difficult to spot. In the preferred embodiment, therefore, the emergency call generator is a radio transmitter operating in the VHF frequency band. Such a radio tranmitter possesses a relatively large transmission range and low power consumption and may be readily spotted by a simple directional receiver or radiogoniometer.

On the other hand the invention also relates-as stated above-to an inclination switch, particularly adapted for such emergency transmitters.

Known inclination switches are the so-called mercury switches in which a small amount of mercury is sealed in a glass or quartz tube and serves as connecting bridge between contact electrodes piercingly extending into the mercury containing tube. These mercury switches are generally used in stationary installations or in such equipment in which the risk of breakage of the mercury containing tube and of the consequences of the mercury flowing out is so to say negligible.

The invention thus also seeks to provide an improved inclination switch which is completely safe and which as a mercury switch-is responsive to any inclination, regardless about which axis such an inclination occurs. The invention also seeks to provide a safe inclination switch which is particularly adapted for use in an emergency transmitter.

According to the invention there is provided an inclination switch comprising a hollow body defining a hollow space, first and second contact electrodes arranged in spaced and in electrically insulated relationship within said hollow space, said hollow space being partially filled with a free-flowable, electrically conducting medium, said medium being adapted to electrically connect the first and the second contact electrode in response to the position of said hollow body, said medium consisting of loose solid particles of at least one electrically conducting material.

The invention will be further described by way of example with reference to the accompanying drawings, in which: Figure 1 shows a simplified block circuit diagram of an emergency transmitter comprising a radio transmitter, Figure 2 shows an embodiment of the housing for the emergency transmitter of Fig.

1, Figure 3 shows a simplified front and side views of a capacitive inclination switch, Figure 4 is an example of a circuit associated to the capacitive inclination switch of Fig.

3, Figure 5 depicts a simplified front and side view of a mechanical inclination switch, Figures 6 to 8 illustrate sectional views of a preferred embodiment of the inclination switch according to the invention, and Figure 9 a modified embodiment of the inclination switch of Figs. 6 to 8.

Reference is first made to Figs. 1 and 2.

The illustrated emergency transmitter 10 comprises a housing 11 substantially in the shape of a slightly bent cuboid. Such housing 11 is provided with a band or strap 12, by means of which the housing 11 may be fastened or strapped to a part of the human body which normally is in a predetermined position or deviates only slightly from such position. For example this part could be the upper body or upper arm. The front wall 1 3 of the housing may be provided with guide or retaining rails, for receiving and holding a ticket or a identification card enabling the bearer to make use of a public transport means such as a ski- or chair-lift or the like. The housing 11 is preferably completely water tight.A removable cover is provided for giving access to a battery compartment 1 6 housing the only components which are to be exchanged from time to time, namely batteries 1 7 (Fig. 1).

The circuit of the emergency transmitter will now be described with particular reference to Fig. 1. The batteries 1 7 (one or more cells) are the power source for a radio transmitter transmitting via an antenna 1 9 preferably a VHF-frequency, either modulated by means of a low frequency modulator 18' or unmodulated. The transmitting frequency of the radio transmitter may be adjustable, so that in the event several emergency transmitters are in use the one emanating an emergency call may be identified by the received frequency. The transmitting antenna 1 9 may be incorporated in the band or strap 12.

A main switch 21, preferably a mechanical, hand operated switch positioned-as seen in Fig. 2-at a less accessible side of housing 11-is provided to switch-on the emergency transmitter in a stand-by or ready condition.

Connected in series with the main switch 21 there is provided a hand switch assembly 22 shunted by an additional switching circuit 23 responsive to variations of position of housing 11.

The additional switching circuit 23 comprises an inclination switch 24, which is series connected with an normally closed contact 25 and a delay circuit 26. The delay circuit 26 is responsive to the closing of the inclination switch 24 and adapted to gate such closing or connect through after a certain delay time of e.g. thirty seconds, and therefore to switch-on the radio transmitter 1 8 even if the hand switch assembly 22 is still open. The inclination switch 24 is connected to the delay circuit 26 by a conductor 28. A warning device, for example a buzzer 29 is connected in parallel to conductor 28 and ground conductor 27. Such warning device therefore provides an undelayed indication of the closing of the inclination switch 24.The buzzer 29 or other acoustical warning device may be arranged within the housing 11 in the vicinity of slots 30 in the front wall 1 3 of housing 11, to emanate therethrough an acoustical warning signal. Such warning signal informs the bearer of the emergency transmitter that the inclination switch has been closed and that the switching-on of the radio transmitter 1 8 will follow after a delay time determined by delay circuit.

If a bearer is in a position to hear the warning signal and if he is of the opinion that there is no need to switch-on the radio transmitter, he may deenergize the buzzer 29 and the delay circuit 26 by opening the normally closed contact 25 by means of a push-button 31 associated thereto. However, the pushbutton 31 and the normally closed contact 25 not of are not of bistable type. On the contrary, the normally closed contact 25 after actuation of push-button 31, closes again with a delay time of say a few minutes. To this end the normally closed contact 25 has associated thereto its own delay element 32.

It is to be understood that the term "inclination switch" is used in its broadest sense.

Per se it would be possible to use a mercuryswitch with a torus shaped housing, such switch being fixedly mounted in housing 11 of the emergency transmitter in such a way, that it closes as soon as the housing 11 is tilted about any axis out from the position shown in Fig. 2.

Also, an inclination switch may be used in which the position detecting element is a pendulum disk. Such a pendulum disk 33 is sketched in dotted lines in Fig. 2. It is secured to a pin 34, which is rotatably mounted in housing in a direction substantially perpendicular to front wall 1 3. The pendulum disk 33 has attached thereto a weight body 35 extending over a small portion along the periphery of disk 33. As depicted in Fig. 3 the position of disk 33 may be detected capacitively. To this end the disk 33 may be provided at its periphery and diametrically opposite to weight body 35 with an electrically conductive layer 36, which, in the normal position of housing 11, faces a further electrically conductive layer 37 fixed at the housing 11.Thus, the conductive layers 36, 37 constitute a capacitor 38, the capacitance of which varies according to the rotational position of disk 33.

A possibility for detecting these variations of capacitance is the bridge circuit illustrated in Fig. 4. This bridge circuit is energized by an oscillator 40 and comprises in one of its branches the capacitor 38 and in its other branch a reference capacitor 39 of constant value. As soon as the bridge circuit is no longer in balance, there will be a voltage between the junctions 41, 42 of the branches of the bridge circuit. Such voltage may be amplified by an amplifier and such amplified voltage may be used to fire a semiconductor switch (not shown), which in turn energizes the delay circuit 26 and the buzzer 29.

The pendulum disk may also be the support of the movable contact of a simple normally open switch. As illustrated in Fig. 5, in this embodiment the pendulum disk 33 is provided, at a diametrally opposite side of weight body 35, with a contact pin 44 which cooperates, depending on the direction of rotation of disk 33 with a pair of fixed contact pins 45, 45' and 46, 46' and thereby electrically connects the pins of a respective pair.

The inclination switch 24 shown in Fig.

6-8 comprises two metallic, dome shaped shells 111, 11 2 which are secured with their respective edges 113, 114 to a facing end edge of a ring 11 5 of insulating material. The shells 111, 11 2 may be bonded to ring 11 5 by an adhesive or the like. Each of the shells 111, 11 2 constitutes a part of a housing and at the same time a contact electrode, and the shells 111, 11 2 define together with insulating ring 11 5 a spheric hollow space 116. The hollow space 11 6 contains a certain amount of a powder or particulate of an electrically conductive material, such as metal powder, carbon or a mixture of both.The filling height of this powder or particulate material is indicated by arrow 117. The shell 111 is provided with a terminal 11 9 and the shell 11 2 with a terminal 120, which terminals are disposed in this embodiment at the apex of the respective shell. A contact pin 121 is secured to shell 11 2 and extends from the apex thereof towards the apex of shell 111.

The distance between the free end of contact pin 121 and the facing apex of shell 111 is indicated by arrow 122, which distance is smaller than the filling height indicated by arrow 117.

If the inclination switch of Fig. 6 with its powder or particulate filling is turned about any axis into the position of Fig. 7, an electrical connection between the shells 111 and 11 2 is established via the powder or particulate 11 8: the switch is thus closed. If the switch is further rotated until it reaches the position of Fig. 8, the switch 24 remains closed, because the free end of contact pin 121 remains dipped in the powder or particulate 118.

The response threshold of the shown inclination switch, that is the minimum angle of inclination necessary for closing the switch may be adjusted by varying the quantity, i.e.

the filling height of the powder or particulate material 11 8 and/or by reducing the axial thickness of insulating ring 115, i.e. by reducing the distance between the edges 113, 114 of the shells 111 and 11 2, respectively.

The embodiment shown in Fig. 9 differs from that in Figs. 6-8 essentially in that apart from terminals 119, 1 20 no electrically conductive part is accessible from the outside.

This last embodiment comprises a housing assembled from two hemispherical shells 123, 124, which are secured one to the other with facing open sides. At the inner side of the two shells 123, 1 24 there is a metallic layer 125, 126, respectively, which does not extend to the end edges of the respective shell. These layers 125, 1 26 constitute the contact electrodes.

The hollow space 11 6 defined by the two shells 123, 1 24 holds-as in the embodiment of Figs. 6-8-a certain quantity of the powder or particulate material 11 8. The terminals 119, 1 20 are electrically connected to the respective layer 125, 1 26 and moreover the terminal 1 20 is provided with an extension forming the contact pin 121. The operation of the inclination switch of Fig. 9 is substantially the same as that of the embodiment of Figs. 6-8.

Turning again to the operation of the emergency transmitter described with reference to Fig. 1 and 2 it is to be noted that it offers many advantages. Firstly the bearer may consciously or deliberately transmit an emergency call. Secondly the emergency call is also transmitted automatically as soon as the housing gets in to a position which deviates to a substantial extent from its normal position.

The automatic transmission of the emergency call is, however, preceded by an acoustical warning and the bearer may then still prevent the automatic transmission, if he is still able and willing to do so. If the bearer does not prevent the automatic transmission of the emergency call, such call will be received by a suitable DF-receiver or radiogoniometer which in turn will spot the location of the emergency transmitter. Since in this case the buzzer 29 remains energized the search for the location of the emergency transmitter will be further assisted. If, for example a skier equipped with the present transmitter is buried by an avalanche and other skiers notice the accident, these other skiers may immediately take up the rescue and the buzzer alone may assist them in precisely spotting the location of the buried skier.

Companies operating ski- or chair-lift or the like transportation facilities may be bound to provide for a rescue service. Such companies may organize their rescue service with less personnel and more efficiently by installing suitable DF-receivers or radiogoniometers and by providing the public making use of these transportation facilities with emergency transmitters of the type described.

Claims

1. A portable emergency transmitter comprising a housing, a power source within said housing, an emergency call generator within said housing, a hand switch assembly for connecting said emergency call generator to said power source, additional switch means responsive to variations of positions of said housing, a delay circuit series connected to said additional switch means, said additional switch means and said delay circuit being adapted for delayed switching-on said emergency call generator in response to a variation of position of said housing.

2. The emergency transmitter of claim 1, wherein said emergency call generator is a radio frequency transmitter and wherein indicator means are provided to indicate response of the additional switch means without delay.

3. The emergency transmitter of claim 2, wherein the indicator means comprise a sound generator.

4. The emergency transmitter of claim 3, wherein said sound generator is a buzzer.

5. The emergency transmitter of claim 2, comprising means for disactivating the additional switch means upon response thereof during a predetermined period of time.

6. The emergency transmitter of claim 1, wherein the additional switch means comprise an inclination switch.

7. The emergency transmitter of claim 2, wherein said radio transmitter comprises a feeder circuit, in which said hand switch assembly is inserted, said additional switch means and delay circuit shunting said hand switch means in said feeder circuit.

8. The emergency transmitter of claim 6, wherein said inclination switch comprises a variable capacitor changing its capacity in response to the position of said housing.

9. The emergency transmitter of claim 5, wherein said disactivating means comprise a normally closed contact series connected to said additional switch means, a hand operated button for opening said normally closed contact and a delay element for delayed closing said normally closed contact upon the opening thereof.

1 0. A portable emergency transmitter, comprising a housing, a power source within said housing, an emergency call generator including a radio transmitter within said housing, a hand switch assembly for selectively connecting said radio transmitter to said power source, additional switch means including an inclination switch responsive to variations of position of said housing, a delay circuit series connected to said additional switch means, said additional switch means and said delay circuit shunting said hand switch assembly for delayed switching-on said radio transmitter in response of a deviation of said housing from a predetermined position.

11. An inclination switch, particularly for an emergency transmitter, comprising a hollow body defining a hollow space, first and second contact electrodes arranged in spaced and electrically insulated relationship within said hollow space, said hollow space being partially filled with a free-flowable, electrically conducting medium, said medium being adapted to electrically connect the first and the second contact electrode in response to the position of said hollow body, said medium consisting of loose solid particles of at least one electrically conducting material.

1 2. The inclination switch of claim 11, wherein each contact electrode comprises a contact surface said surface defining partially said hollow space.

1 3. The inclination switch of claim 12, wherein said contact surfaces of said contact electrodes are dome shaped.

14. The inclination switch of claim 13, wherein said contact surfaces of said contact electrodes are in the shape of a spherical calotte.

15. The inclination switch of claim 14, wherein said contact surfaces of said contact electrodes have a circular edge, an insulator ring having two end edges, each circular edge being secured to a respective end edge of said insulator ring.

16. The inclination switch of claim 1 3, comprising a hemispherical hollow shell of an insulating material for each contact electrode, said shell having a concave side, said contact electrodes being a metal layer on the concave side of the respective hemispherical shell.

1 7. The inclination switch of claim 13, wherein each of said contact surfaces has an apex and wherein one of said contact electrodes comprises a contact pin having two ends, one end of said contact pin being connected at the apex of the respective contact surface and the other end of said pin being positioned in the vicinity of the apex of the contact surface of the other contact electrode.

1 8. The inclination switch of claim 11, wherein said free-flowable electrically conducting medium is selected from the group consisting of metal powder, carbon powder and a mixture of metal and carbon powder.

19. A portable emergency transmitter constructed and arranged to operate substantially as hereinbefore described with reference to Figs. 1 to 9 of the accompanying drawings.

20. An inclination switch constructed and arranged to operate substantially as hereinbefore described with reference to Figs. 6, 7 and 8 or Fig. 9 of the accompanying draw ings.