A SECURITY SYSTEM FOR CONTROLLING THE POWER CIRCUIT OF A MOBILE TELEPHONE

Abstract: The invention relates to a security system, in which a current supply circuit (1) is provided with a number of battery cells (2) and mounted in casing (3) for a replacement battery for a mobile telephone (4) in a cellular radio network, the current supply circuit comprising a switching means (6) for a supply voltage for the mobile telephone. According to the invention the current supply circuit is supplemented by a control means (10), which is arranged for locking a turn-on button (8) of the mobile telephone in a depressed position, as well as by signal receiving means (5), which are arranged to control the switching means to turn on the supply voltage in response to an activation signal, so that signal transmission may be provided between the mobile telephone and a supervision terminal (7) in the security system.

Description: A SECURITY SYSTEM FOR CONTROLLING THE POWER CIRCUIT OF A MOBILE TELEPHONE Technical field of the invention This invention relates to a security system, in which a current supply circuit is provided with a number of battery cells and mounted in a casing for a replacement battery for a mobile telephone in a cellular radio network. State of the art Security systems including a mobile telephone in a cellular radio network are previously known both for fixed and mobile protected objects. Unlike ordinary telephones in line restricted networks mobile telephones in cellular radio networks emit signals now and then even in state of rest. This is a security risk, because other equipment may be disturbed by the radio signals and further, these may easily reveal the presence of the mobile telephone for unauthorised persons, when it forms a part of a concealed security system. Disclosure of the invention The invention relates to a security system, in which a current supply circuit is provided with a number of battery cells and mounted in a casing for a replacement battery for a mobile telephone in a cellular radio network. An object with the invention is to avoid unnecessary interference with other equipment by the mobile telephone. Another object with the invention is to prevent that the presence of the mobile telephone is revealed to unauthorised persons. Further objects with the invention will be evident below from the description of the drawing. According to the invention said current supply circuit includes signal receiving means, which are adapted to control a switching means for a supply voltage to the mobile telephone in order to provide a signal transmission between the latter and a supervision terminal in the security system. Description of the drawings The description below relates to a preferred embodiment of a security system including a mobile telephone according to the invention, which is illustrated in the accompanying drawing, in which: Figure 1 is a perspective view of the preferred embodiment, figure 2 is a block diagram of the embodiment in figure 1, and figure 3 is a supplementary perspective view. Preferred embodiment Figure 1 is a perspective view of the preferred embodiment, in which a security system in accordance with the invention includes a current supply circuit 1, which in this example is provided with four battery cells 2, and which is mounted in a casing 3 for a replacement battery for a mobile telephone 4 in a cellular network. In figure 2 the same designations numerals are used as in figure 1, and figure 2 shows a block diagram of the preferred embodiment of the security system. According to the invention the current supply circuit 1 advantageously includes a signal receiving means 5, which is provided with a microprocessor, and which is adapted to control a switching means 6 for a supply voltage to the mobile telephone 4 and thereby providing a signal transmission between the latter and a supervision terminal 7 in the security system. The security system according to the invention can be used for automatically switching off the mobile telephone 4 when it is brought into a protected zone, and then the switching means 6 is adapted to switch off said supply voltage in response to an inhibiting signal received by the signal receiving means 5 from the supervision terminal 7. In accordance with the example in the drawing the signal receiving means includes an electroacoustical transducer, which is adapted to be influenced by signals inside or outside the audible interval. In order to limit the protected zone more precisely, the signal receiving means 5 may alternatively be adapted to be influenced by capacitively transmitted signals, which are controlled from the supervision terminal 7, and then the electroacoustical transducer is replaced by a capacitor, which simply can be formed by a copper foil in a circuit board provided for the current supply circuit 1. The signals are preferably emitted in the frequency band 10-100 kHz. The security system according to the invention may also be used for automatically switching on the mobile telephone 4, when it is brought out from the above mentioned protected zone. For this purpose the switching means 6 is arranged to switch on said supply voltage in response to an activation signal, which is received by the signal receiving means 5, and, as is described more detailed below, the current supply circuit 1 is supplemented by a control means for automatically switching on the mobile telephone 4, when the supply voltage is switched on by the switching means 6. The automatic switching off and on of the mobile telephone 4 in the security system according to the invention may for example be helpful for users under stress. They do not have to switch off the mobile telephone 4 manually, when this is brought into a conference room or a protected area in a hospital, and later have to switch on the mobile telephone manually. Figure 3 is a supplementary perspective view of the preferred embodiment of the mobile telephone 4 in the security system according to the invention. In order to turn on the mobile telephone 4 automatically when the supply voltage is switched on by the switching means 6 , the above mentioned control means is arranged for locking a turn-on button 8 of the mobile telephone 4 in a depressed position. According to the example shown in the drawings the control means is a blocking device, which is arranged in a protective casing 9 for the mobile telephone 4 as an inwards directed protrusion 10, which automatically provides the blocking of the turn on button 8 in the depressed position, when the mobile telephone 4 has been pushed into the protective casing 9. In the security system according the invention the supervision terminal 7 may be stationary installed in a very limited protection zone with a local transmission between the terminal an the mobile telephone 4 via radio, capacitive coupling or sound inside or outside the audible interval, as described above. For other applications the supervision terminal 7 may be located anywhere in the cellular network of the mobile telephone 4. For example, the signal receiving means 5 may be arranged to be influenced by such an acoustic signal of inaudible frequency, which normally appears in a closed room when a door or a window is opened, and which then will have the function of the above mentioned activation signal for turning on the supply voltage to the mobile telephone 4. In this application the supervision terminal 7 is arranged to send a message to the mobile telephone and to receive a message confirming the receipt of the former, thereby being notified that said activation signal has occurred. Preferably the supervision terminal 7 is arranged to be able to automatically send a further message to the mobile telephone 4 as a response to the receipt of said confirmation in order to be able to be notified of said activation signal also the next time, as well as automatically send messages to a number of contact persons in response to the receipt of said confirmation. Further the supervision terminal 7 is optionally arranged to automatically receive a message with a geographical position of the mobile telephone 4 from e.g. a hidden place in a stolen car, the mobile telephone 4 then being a GSM telephone, said messages being SMS messages and the cellular network being arranged for computing said geographical position in a manner known per se. A GSM telephone for pocket use is adequate as a simple embodiment of the supervision terminal 7 in an application of the last mentioned kind, where the signal receiving means 5 is influenced by such an acoustic, inaudible signal which indicates that a door or a window is being opened in a closed room. According to the example the signal receiving means 5 is an electret microphone with an amplifier without filter for low frequencies. With the addition of an amplifier with a proper bandpass filter, the same signal receiving means 5 may be used to be influenced by acoustical signals generated by an external alarm means, e.g. a distress alarm siren, an automatic fire alarm, a burglar alarm or a sound generator in a pager, to which the supervision terminal 7 is arranged to send a message. In the latter case the signal receiving means 5 is arranged to be influenced indirectly by radio signals controlled from the supervision terminal 7. In an alternative embodiment the electroacoustical transducer is supplemented or replaced by a pager receiver mounted in the casing 3 for the replacement battery for the mobile telephone 4. All technical details are well known to anyone skilled in the art and will therefore not be described in detail . The security system according to the invention can be embodied in many different ways within the scope of the appended claims. According to the example, the battery cells 2 in the current supply circuit 1 are rechargeable and provided with an overcurrent protection 11, over which a control voltage can be obtained when the mobile telephone is being charged, the switching means 6 being arranged to be maintained in a connected state until the battery cells 2 have been charged. The signal receiving means 5 may be arranged to control the switching means 6 in such a manner, that the activation signals cause the supply voltage to the mobile telephone 4 to be turned on for e.g. one minute and then turned off with at least one repetition within a supervision period of e.g. four minutes. Hereby a break in a started signal transmission between the supervision terminal 7 and the mobile telephone 4 may be detected by the lack of repetition, and further the signal transmission may be coded in respect to different causes behind the activation signals. If you e.g. choose one repetition at the end of the supervision period to indicate detection of such an acoustic signal of inaudible kind, which occur when a door or a window is opened in a closed room, then two, three and four repetitions within the supervision period may be used to indicate acoustical signals, which are generated by available embodiments of burglar alarm devices, fire alarms and distress alarm sirens, respectively.

Claims: Claims 1. A security system, in which a current supply circuit (1) is provided with a number of battery cells (2) and mounted in a casing for a replacement battery for a mobile telephone (4) in a cellular radio network, the current supply circuit comprising a switching means (6) for a supply voltage for the mobile telephone, characterized in, that the current supply circuit is supplemented by a control means (10) , which is arranged for locking a turn-on button (8) of the mobile telephone in a depressed position, as well as by signal receiving means (5) , which are arranged to control the switching means to turn on the supply voltage in response to an activation signal, so that signal transmission may be provided between the mobile telephone and a supervising terminal (7) in the security system. 2. A security system according to claim 1, characterized in, that said control means is a blocking means, which is arranged in a casing (9) for the mobile telephone in such a manner, that said locking of the turn-on button is achieved automatically when the mobile telephone is in the intended position in said casing. 3. A security system according to claim 1-2, characterized in, that said supervision terminal is arranged to transmit a message to the mobile telephone, to receive a message confirming the receipt of the former thereby being notified that said activation signal has appeared, and to automatically be able to send a further message to the mobile telephone in response to the receipt of said confirmation to be able to be notified of said activation signal also the next time. 4. A security system according to claim 1-3, characterized in, that said supervision terminal is arranged to be able to sent messages automatically to a number of contact persons in response to the receipt of said confirmation. 5. A security system according to claim 1-4, characterized in, that said supervision terminal is arranged to be able to receive automatically a message with a geographic position of said mobile telephone. 6. A security system according to claim 3-5, characterized in, that said messages are SMS messages, said mobile telephone being a GSM telephone and said cellular network being arranged for calculating said geographical position. 7. A security system according to claim 1-6, characterized in, that said signal receiving means includes a pager receiver, said supervision terminal being arranged to be able to send a message to said pager receiver. 8. A security system according to claim 1-7, characterized in, that said signal receiving means are arranged to be influenced by such an acoustic low frequency signal, which normally is generated in a closed room when a door or a window is opened. 9. A security system according to claim 1-8, characterized in, that said signal receiving means are arranged to be influenced by acoustic signals, which are generated by an external alarm means. 10. A security system according to claim 9, characterized in, that said external alarm means is a sound generator in a pager, to which said supervising terminal is arranged to send a message.

Inventors: JOHANSSON JAN, WERN LARS, WIDGREN ANDERS, JOHANSSON, JAN, WERN, LARS, WIDGREN, ANDERS
Applicants: JOHANSSON JAN, WERN LARS, WIDGREN ANDERS, JOHANSSON, JAN, WERN, LARS, WIDGREN, ANDERS
Application year: 2000
Main classification: H04Q7
IPC codes: H04B1, H04W52