DETECTING DEVICE

Abstract: A device for detecting the opening of a lid equipped valuables transport case (1, 3) has a light emitter, a light sensor and light guides disposed therebetween (11-14, 21-24) which include light guide sectors disposed alternately on the case lid (3) and the remainder (1) of case, especially around and adjacent the edge area of the lid. When the lid is closed, modulated light can be transmitted from the light emitter to the light sensor through the light guides. Opening the lid breaks the light path through the light guides. Detecting a break in light transmission gives an indication of opening of the lid (3).

Description: DETECTING DEVICE Technical Field The present invention relates to a device for detecting the opening of a "security case" used for the transport of valuable documents and hereafter referred to as a valuables transport case. The invention is particularly , intended to detect any attempts to gain unauthorized entry into the case or tamper with its interior cavit . Background art A valuables transport case is typically fitted with various sorts of alarm devices to detect unauthorized attempts to open or tamper with the case, and upon so doing to trigger, for example, a "dye bomb" resulting in dying of the banknotes, for instance, being transported in the case. Object of the invention The object of the present invention is to provide a devic of the type defined in the opening passage which, in its function, is very secure, which has a very simple construction, consists of inexpensive, simple components and can be easily fitted for all-round detection. A further object is to provide a device of the above type which additionally gives the possibility of detecting attempts to introduce powder, smoke or the like into the protected cavity which could prevent dying of the transported valuables upon triggering of a dye bomb. Summary of the invention The abovementioned objects are attained by a device in accordance with the invention having the features defined in the accompanying claims. Accordingly, the device of the invention is essentially distinguished in that it comprises a light emitter, a light sensor, light guide means disposed between the light emitter and light sensor for guiding light emitted by the light emitter to the light sensor and means to control and monitor light transmission from the light emitter to the light sensor to provide a signal which indicates whether the prescribed light transmission is present. The said light guide means includes first light guide sectors disposed on the lid of the case and a second light guide sectors disposed on the means defining the cavity of the case such that when the case is its unopened state the first and second light guide sectors mutually connect and enable light transmission from the light emitter to the light sensor through the serially connected light guide sectors and such that when the case is in its opened state, the light guide sectors are separated and do not allow this light transmission. Accordingly, the light guide means comprises several of the first light guide sectors and several of the second light guide sectors alternately arranged in this fashion. It will be apparent without further elaboration that the light guide means can be readily arranged all the way around the edge region of the lid and the opening of the case, respectively. Accordingly, the device of the invention can be readily arranged to provide comprehensive monitoring, for example along an appreciable length of the critical bordering region of the lid of the case. Advantageously, the light guide means can consist of conventional optical fibre which is cheap, robust, can have small dimensions and is easy to apply with regard to the desired geometrical configuration. Similarly, the light emitter and light sensor can advantageously utilize conventional light emitting diodes or laser diodes, and photodiodes or phototransistors, respectively. These components are also well proven, small, cheap and simple to operate and include in electronic circuits. With the aim of providing further enhanced security, the light passing through the light guide means is modulated, the sensed light which has passed through the light guide means being correspondingly demodulated to verify that th transmitted light has not been tampered with. Accordingly and advantageously, the light emitted by the light emitter can be varied or modulated randomly or stochastically, the light sensor being phase-locked to th emitted light signal thereby to obtain controlled light sensing or demodulation. In this manner, it is possible t easily verify if any attempt has been made to tamper with the light transmission using steady or pulsed light. A configuration with separate light guide sectors lying i series, one after the other, also provides the possibilit of an extra security function. According to the invention the mutually adjacent light guide sectors, preferably alternating first and second light guide sectors, can be separated by intermediate spaces such that light transmission is not prevented in the normal course of events but light transmission is immediately prevented if solid material, smoke etc is introduced into the cavity o the case and therefore into said intermediate spaces between the light guide sectors. In consequence, occurenc of the latter leads to the same result as an attempt at unauthorized opening. The invention will now be further described in relation to an exemplary embodiment and with reference to the accompanying drawings. Brief description of the drawings Fig. 1 is a schematic perspective view of a valuables transport case with the lid open, illustrating the placing of light guide means in accordance with the invention. Fig. 2 is a schematic diagram which additionally illustrates the light guide arrangement,- including the light emitters, light sensors and intermediate light amplification units. Fig. 3 is a schematic block diagram of a device in accordance with the invention with associated electronics. Description of the embodiment The valuables transport case shown in Fig. 1 includes a lower case portion 1 and an upper lid- 3 attached with hinges. A central valuables transport cavity is defined within the case portion, covered by an inner lid 5. A battery compartment 7 is located at one side of the valuables transport cavity, while an electronics compartment 9 is located at the other side. Fiber optic light guides are disposed in a rectangular configuration on the inside of the lid 3 and under the inner lid 5, respectively. Accordingly, four straight light guide sectors 11, 12, 13, 14 in parallel pairs are disposed on the inside of the lid in the middle of the respective side edge areas. The length of the respective light guide sectors is, by and large, half of the length of the corresponding side. The light guide sectors 11, 12, 13, 14 can be affixed in an appropriate manner, for example by gluing directly to the inside of the lid or with a special holder. It will be appreciated that the respective light guide sectors 11 to 14 can consist of a plurality of light guid portions connected in series, but with small intermediate spaces between portions in order to enhance the earlier described extra function. Recesses or slits 15, 16, 17, 18, corresponding to the light guide sectors 11-14, are located in the inner lid 5 through which the light guide sectors pass to a working position under the inner lid 5 when the lid 3 is closed. Complementing light guide sectors 21, 22, 23, 24 are located under the inner lid 5, each having an angle configuration and connecting to the light guide sectors 11-14 via short intermediate spaces to form a rectangular shaped light guide loop. Light guide sectors 21-24 can be disposed on the undersid of the inner lid or on a special mounting means in an appropriate fashion. These light guide portions can have continuous, angled configuration, or more preferably consist of two parts a, b, extending at right angles and linked together by a light amplification unit respectivel connected to a light emitter and a light sensor, as is evident from Fig. 2. Fig. 2 illustrates the functioning of the light guide arrangement when the lid is closed. A light emitter, preferably a light emitting diode, is located at a first corner of the resulting rectangular configuration and transmits light into the light guide 21a. The light travels via light guides 12 and 22a to the next corner where it is amplified by a light amplification unit 27 which includes a photodiode 28, an amplifier (not depicted) and a light emitting diode 29 and which transmits amplified light onward along the next side of the rectangle. Light transmission proceeds further utilizing light amplification units 30, 31 at the two remaining corners as well. The light finally travels through the light guides 24b, 11, and 21b back to a light sensor disposed at the first named corner. This is preferably a photodiode or a phototransistor. As will be appreciated without further elaboration, opening the lid 3 immediately breaks the optical path through the light guides which means that the light sensor 33 no longer picks up any light causing its output signal to cease. This state can be easily detected and represents an indication that opening has occurred. Short intermediate spaces 35 are located between the various light guide sectors or portions extending along four straight lines defining mutually parallel pairs. Typically, the intermediate spaces 35 have a length of one or more millimetres so that they do not markedly attenuate light transmission. However, it will be apparent that if smoke for example is introduced into the intermediate spaces 35, the light transmission is immediately severely attenuated i.e. practically speaking it is cut off. In this event a similar state is reached as with the opening of the lid. Corresponding intermediate spaces can also be disposed adjacent the light amplification units 27, 30, 31, the light emitter 25 and the light sensor 33. Fig. 3 schematically illustrates an example of a circuit which utilizes the present invention and which can be built into a valuables transport case. A microprocessor 41 controls and monitors the device. A modulator 43 provides input to the light emitter 25 and can comprise an oscillator with fixed or variable frequency or a combination thereof. Functioning of the modulator 43 is controlled by the microprocessor 41. The light sensor 33 emits a signal on a line 45 depending on the light received from the light emitter 25 via the light guides. This signal is conveyed to a comparator 47. which, via line 49, also receives the signal transmitted by the modulator to the light emitter 25. The comparator 47 compares both of the received signals, i.e. compares the transmitted and received light. The result of this comparison is transmitted via a line 51 to the microprocessor 41 which initiates appropriate measures depending on the signal received, for example triggering a dye bomb.

Claims: CLAIMS 1. A device for detecting the opening of a valuables transport case which has a lid (3) connected to a cavity defining means (1) which is preferably case shaped, characterized in that it comprises a light emitter (25), a light sensor (33), light guide means (11-14, 21-24) arranged between the light emitter and the light sensor to guide light emitted from the light emitter to the light sensor and means (41, 43, 45, 47, 49, 51) to control and monitor the light transmission from the light emitter (25) to the light sensor (33) to produce a signal which indicates whether the prescribed light transmission is present, said light guide means including a plurality of first light guide sectors (11-14) disposed on the lid (3) of the case and a plurality of second light guide sectors (21-24) disposed on the cavity defining means (1) of the case such that when the case is in its unopened state, alternating first and second light guide sectors connect with each other and enable light transmission from the light emitter (25) to the light sensor (33) through the light guide sectors and such that when the case is opened, the light guide sectors are separated and do not allow such light transmission, and wherein said means to control and monitor the light transmission is arranged to initiate modulation of the light emitted by the light emitter (25) and, after demodulation of the received light, to analyse whether the result of the demodulation corresponds with the modulation. 2. A device according to claim 1, characterized in that said means (41, 43, 45, 47, 49, 51) to control and monitor the light transmission is arranged to provide stochastic modulation of the light emitted by the light emitter (25) and to phase-lock the light sensor (33) in correspondence thereto. 3. A device according to claim 1 or 2, characterized in that said light guide means (11-14, 21-24) is disposed in an all-round configuration adjacent the edge regions of the lid (3) of the case and its opening, respectively. 4. A device according to any preceding claims, characterized in that first and second light guide portions (11-14 and 21-24, respectively) in the unopened, state are separated by intermediate spaces (35) such that light transmission in the normal course of events is not prevented but light transmission is prevented if solid material, smoke etc is introduced into the cavity and thereby into said intermediate spaces. 5. A device according to any preceding claim, characterized in that said light guide means (11-14, 21-24) includes optical fibre. 6. A device according to any preceding claim, characterized in that light amplification units (27, 30, 31) are disposed between mutually adjacent light guide sectors (22a, 22b; 23a, 23b; 24a, 24b) distributed betwee the light emitter (25) and the light sensor (33). 7. A valuables transport case comprising a device according to any preceding claim.

Inventors: OESTERBERG ANDERS, OESTERBERG, ANDERS
Applicants: SECURITAS AB
Application year: 1993
Main classification: E05G1
IPC codes: E05G1, G08B13