REMINDER ALARM SYSTEM

Abstract: An alarm system comprising at least one emitter (1) and at least one receiver/alarm sounder (2). These elements are arranged to trigger off an alarm when the distance between them exceeds a predetermined value. The alarm thus is triggered off when the signal received by the receiver (2) is below a predetermined value. The alarm system in accordance with the invention comprises in accordance with one preferred embodiment thereof a central receiver/alarm sounder (2) and a number (one or several) emitters (1) which are attached in or on personal valuable objects. When such a valuable object is removed the receiver which may be positioned in the vicinity of the owner, sounds an alarm.

Description: REMINDER ALARM SYSTEM The subject invention concerns an alarm system the primary function of which is to serve as a memory aid, that is, to help persons to avoid losing valuable objects and similar articles. Conventional alarm systems are designed with a view to function e.g. as theft-preventive means, burglar alarms and so on. In general they are designed to be permanently installed in stores, shops, libraries, storage premises, exhibition halls, cars etcetera. As one example of alarm systems of this kind may be mentioned a system comprising magnetic codes attached to the objects to be guarded. When the object is bought or the loan thereof registered the code is demagnetized and the object may be removed from the shop or the library without activating the alarm system which is designed to sound an alarm if an object carrying a non-demagnetized code is removed from the shop/library. This wellknown alarm system functions in the following manner. A detection zone is established adjacent the exit and when an object carrying a non-demagnetized code enters this detection zone the presence of the object is sensed and an alarm is sounded. Objects carrying a demagnetized code has no effect on the alarm system. When used in applications where the objects are on loan, for instance as is the case in libraries, the code of the object may be re-magnetized upon return of the object and the latter will once more be protected by the alarm system. Other exa plers of alarm system are systems of the kind comprising a central unit in the form of an emitter/receiver to which are connected units in the form of staff location units carried by individuals. Staff location units of this kind also comprise an emitter which upon activation sounds an alarm in the central unit. The purpose of the subject invention is to provide an alarm system which is adapted to serve primarily as a memory aid and to prevent the person using the system from losing OMPI or mislaying valuable ' objects, either by negligence or forgetfulness. To achieve this purpose the system in accordance with the invention is characterized therein that each unit which is intended to be incorporated in the alarm system, is provided with at least one individual emitter, said emitter arranged, when the alarm system is in an activated state, to be in continuous communication with at least one combined receiver/alarm sounder which is arranged to emit an alarm signal as soon as the distance between at least one of the emitters and the receiver exceeds a certain level, that is, when the strength of the signal transmitted from the emitter or emitters which have been removed, is below a predetermined value. Further characteristics of the alarm system in accordance with the subject invention will become apparent from the following description and the appended dependent claims 2-4. The invention will be described in closer detail in the following with reference to the accompanying drawings, wherein Fig. 1 shows schematically the components incorporated in the system in accordance with the invention, and Fig. 2 is a diagram illustrating the operative interval of the alarm sounder in accordance with one preferred embodiment of the system of the invention. It should be recognized that there are a number of different practical ways of designing an alarm system which functions in accordance with the principles of the subject invention. The alarm system of the subject invention comprises in accordance with one embodiment (see Fig. 1) one or several emitters 1 which are adapted to transmit signals to a receiver/alarm sounder 2. The latter is constructed to trigger off the alarm signal as soon as the signal from one (or several) of the emitters goes below a predetermined level. The OMPI strength of the signal is a function of the distance between the emitter(s) and the receiver. A suitable distance to trigger off the alarm signal is between 1 and 5 metres. The distance may be varied according to choice. An alarm system in accordance with the invention comprising more than one emitter may be designed to ensure that all emitters transmit at their individual frequency and that the receiver senses all these different frequencies. In this manner, the receiver can sense the individual emitters. This provides for exactness of operation of the system. In accordance with the embodiment of the invention illustrated in Fig. 1 the receiver 2 is a unit comprising a loudspeaker 3 adapted to transmit an alarm signal and a number of individual turn-off buttons 4 serving as controls to disconnect reception of signals with selected frequencies when the corresponding emitters 1 are not activated. The reason for the disconnection is to prevent the receiver 2 from mistaking a turned-off emitter 1 for an emitter which is positioned at a long distance therefrom and the rece ved signal of which therefore is weak. Without this disconnection an alarm would have been sounded each time an emitter 1 is turned off. It is likewise possible to provide the buttons 4 with light-emitting diodes or equivalent means to indicate individually which emitter 1 has been removed. A button 5 is also provided to switch off the entire receiver unit 2. The receiver/alarm unit 2 may be carried in a pocket or be suspended from a necklace chain or the like and for this purpose it is provided with e.g. a loop 6. Another possible design of the invention is to use more than one emitter transmitting at the same frequency. The received signal then becomes a signal which is superposed from the various individual emitters and the alarm is triggered off when the strength of the combined received signals is less than a predetermined level, corresponding to the removal of one or several emitters from the receiver. This embodiment makes it possible to control the various emitters individually. Consequently, this embodiment of the invention is more adapted to use in alarm systems comprising a small number of emitters, possibly only one single emitter. The receiver is set according to the number of emitters involved and sounds an alarm when one or several of the latter are removed. A possible modification of the alarm system in accordance with the invention is the arrangement of a central emitter and several receivers/alarm sounders. "These are arranged to sound an alarm when removed too far away from the emitter. The disadvantage of this embodiment of the invention is that the receivers/alarm sounders are comparatively large and therefore difficult to adapt on and inside valuable objects, such as watches, wallets and so on. However, in some appl cations of the invention the size of the objects to be protected or supervised are necessarily quite great and the size of the receivers are of small importance. This is the case with e.g. briefcases. In accordance with this embodiment of the system of the invention, using only one single emitter, only one frequency is used which is sensed by all receivers. The receiver or receivers which is (are) removed from the emitter sound the alarm with the result that it (they) may be traced easily. Fig. 2 is an example of a principle according to which the system of the invention may function. In accordance with this example the system sounds an alarm within a predetermined interval I of the intensity of transmission sensed by the receiver, this intensity corresponding to a distance between the emitter and the receiver in nterval! II. Owing to this arrangement, the problem that the receiver/alarm sounder sounds an alarm also when the emitter is switched off is obviated, since a switched-off emitter corresponds to an infinite distance between the emitter and the receiver, which is outside interval II. OMPI As appears from the aforegoing description, a large number of embodiments on the invention are possible. The purely practical design of the various components used in accordance with the invention is not described herein since such components are well known within the art. The emitters and the rece ver/alarm sounder should be as compact as possible and also their source of energy should be small-size. Emitters including their own source of energy should be small enough to be positioned inside a wallet, a watch, spectacles and other similar small objects. When the emitter is positioned inside a watch it could be connected to the power supply of the watch. The embodiments described in the aforegoing are to be regarded as examples only and a number of different embodiments are possible within the scope of the appended claims. The alarm system may comprise emitters of magnetic type instead of the conventional type of emitters designed to transmit radio signals. Another possible variation of the invention is to use emitters which could be mounted directly on the receiver when they are not mounted on an object. The alarm system in accordance with the invention is primarily intended to serve as a memory aid, that is, to prevent objects from being lost or mislaid by forgetfulness. However, the system could also serve as a burglar alarm, and also to prevent pickpockets. The alarm system may also be used for other pourposes, such as to serve as an aid in looking after children. In the latter case each child is equipped with an emitter and as soon as a child leaves a predetermined area the alarm is sounded. OMPI

Claims: CLAIMS 1. An alarm system, c h a r a c t e r i z e d therein that each unit which is intended to be incorporated in the alarm system, is provided with at least one individual emitter (1), said emitter being arranged, when the alarm system is in an activated state, to be in continuous communication with at least one combined rece ver/alarm sounder (2) which is adapted to emit an alarm signal as soon as the distance between at least one of the emitters (2) and the receiver exceeds a certain level, i.e. when the strength of the signal transmitted from the emitter or emitters which have been removed, is below a predetermined value. 2. An alarm system as claimed in claim 1 for use on personal belongings, c h a r a c t e r i z e d therein that a combined receiver/alarm sounder is adapted to receive the signals transmitted from the emitter or the emitters (1). 3. An alarm system as claimed in claim 1 or 2, c h a r a c¬ te r i z e d therein that the emitter or the emitters (1) are of a kind emitting radio signals. 4. An alarm system as claimed in claim 1 or 2, c h a r a c- t e r i z e d therein that the emitter or the emitters are of a magnetic type. OMPI

Inventors: MILENKO GABRILO, MILENKO, GABRILO
Applicants: TELLO HB, HB TELLO
Application year: 1984
Main classification: G08B13
IPC codes: G08B13, G08B21