The invention relates to a device and a method for securing a room against the undesirable presence of persons.

Especially in commercial and industrial buildings it is customary to secure the rooms present therein against intruders during the time that no personnel or authorized persons are present. In particular in the evening hours and at night such rooms are checked for the presence of undesirable persons by means of detectors provided in several places, which detect for example movements made by a person and which can deliver an alarm signal on the basis of said detection. This may be an acoustic and/or a visual signal, so that the intruders will go away, it may also be a so-called silent alarm signal, however, whereby the detected presence of persons is reported to a certain location, for example a police station, without the intruders being aware of this.

As it is such security systems appear to function well, they are less attractive for securing houses, however, since both the installation and maintenance of such a security system as well as its use involves a great deal of expense.

The object of the invention is to provide an inexpensive security device for the general public, which can be mass- produced because of its simple design and by means of which a effective protection can be realized in a simple and inexpensive manner.

In order to accomplish that objective a normal (standard) telephone connection is according to the invention utilized for securing a room, whereby the security device is provided with a plug for connection to the wall socket of said telephone connection, with a dialling unit comprising switch means for making contact with a selected telephone

number, and with sensors for detecting the presence of persons, which sensors are capable of delivering signals on the basis of which the dialling unit comprising switch means can make contact with a predetermined telephone number.

Since a normal telephone connection is utilized, which is already present in many of the rooms to be secured, no costs need to be incurred for installing the device, whilst the device may be used in a certain room, temporarily for example, and then be taken along to another room to be secured.

According to another aspect of the invention the switch means of the device are designed such that a preprogrammed telephone number is dialled when the sensors deliver a signal, whereby a certain code may be transmitted after the connection in question has been made. Said code may thereby indicate which sensor has made the detection, or it may contain other information. Furthermore the device may be designed such that after the alarm is given a sound connection is made between the device and the location being called, so that it is possible to hear from said location what sounds are being produced in the room being secured.

According to another aspect the device may be provided with the functions of a normal telephone, which makes it possible to reduce the cost of securing a room to a minimum, because configuring a normal telephone as a security device will only involve a limited amount of additional cost. Configuring a telephone as a telephone/se¬ curity device will only involve a small additional amount.

The device according to the invention may be designed such that switching on the alarm takes place by keying a certain code on the normal keypad of the telephone, or by operating

a switch specially provided for that purpose. A delay mechanism may be provided, whereby the security device is for example switched on five or ten minutes after the code has been keyed, so that there is sufficient time to leave the room and/or the house after the code has been keyed. The switch means of the device may be programmed in such a manner that a predetermined telephone number is dialled when the sensors are activated, for example the telephone number of a security service. Furthermore it is possible to programme a telephone .lumber each time the device is switched on, which telephone number is to be dialled in case of an alarm. This may for example be the telephone number of an acquaintance living nearby, who is willing to make an inspection in case of an alarm, but it may also be the telephone number of the location where the person operating the device is going himself, so that he will be able to monitor the room in question himself. In order to be able to switch off the device on returning without the security device being activated, a time span of for example one minute may be programmed between the time that the sensors deliver a signal and the time that contact is made with the preprogrammed telephone number, so that no alarm is given when the security device is turned off immediately after returning.

It is also possible that groups of people living in the same neighbourhood organize a rotating guard duty, whereby there is always one person who will stay at home to receive any alarm signals from the others. Because the cost of such a security system is very small, it is to be expected that small enterprises will be established, which will take care of the security of houses at a local level. Such an enterprise taking care of security by means of devices according to the invention will not necessarily have to confine itself to securing houses, of course it will also be possible to provide security services for commercial and industrial premises and the like in the same manner.

According to another aspect of the invention the plug with which the device is connected to the wall socket of a telephone connection may be of the type into which a second plug can be inserted, so that the device can be connected in parallel with a telephone. In that case the device may utilize the dialling unit of the parallel-connected telephone.

The device according to the invention may be provided with one or more sensors, which are capable of detecting the presence of persons, such as a movement detector, a vibration detector, a sound detector, a light detector, a heat detector, an infrared detector or an ultrasonic detector. Furthermore it is possible to give the device a very conspicuous appearance and/or to provide it with means for delivering sound signals or light signals, so that the presence of the security device will not go unnoticed. Placing it on the windowsill, for example, may have a deterrent effect on potential intruders. Furthermore it may have a positive effect when the device is conspicuously visible for every one entering the room, so that it will be less attractive to return as an uninvited guest.

According to another aspect of the invention the device may be provided with image registration means and with means for transmitting the registered images via the telephone line. This technique of using a telephone line to transmit an image separately or transmit images one after the other in such a manner that a sort of intermitting film is produced, is utilized to an increasing extent and it is to be expected that such an image telephone will be introduced on a larger scale. In that case it will be quite possible to transmit an image or several images of the room being secured along with the alarm signal to the location providing the security service.

According to another aspect of the invention it is possible

to make use of the technique which is used with a wireless telephone, which consists of a master station, which is wirelessly connected to a part of the telephone which is located at some distance from the master station. The part located at some distance from the master station may thereby be provided with one or more sensors for securing the room where said part is placed. In this manner it will also be possible to secure rooms which do not have a telephone connection, but which are not located too far from the room where the master station of the wireless telephone is located.

If sound detectors are used in the security system, a problem may be the fact that sounds which are normally produced in a room, such as the sound of a ringing telephone, may activate the alarm. By using the telephone itself as a security device the security device may be programmed such that the telephone will not ring with incoming calls during the time that the security device is switched on, or that the sound sensor is switched off during said ringing.

Two embodiments of the invention will now be described by way of illustration, with reference to the drawing, in which:

Figure 1 shows a telephone designed as a security device; and

Figure 2 shows a very simple version of a security device.

Figure 1 shows a telephone provided with a receiver 1, which is connected to the master part 3 of the telephone by means of a cord 2. The telephone is furthermore provided with a connecting cord 4, on the end of which a plug 5 is mounted. Plug 5 can be inserted into a conventional wall socket of a telephone connection.

The device shown in Figure 1 can be used as a normal telephone, whereby telephone numbers can be dialled via the push buttons 6. The telephone may thereby be provided with all options that are normally available, for which purpose also other function buttons are provided in addition to those push-buttons that represent a numeral.

In addition to the usual functions of a telephone the device according to Figure 1 comprises a number of sensors, two of which are illustrated in the Figure. On one side sensor 7 is provided, whilst sensor 8 is located on the upper side. These sensors may for example be sound sensors, which are capable of detecting sound produced in the vicinity of the telephone. As already said before, also other types of sensors may be used, however.

The telephone shown may be programmed in such a manner that the securing function is switched on by successively pressing: *, the telephone number of the location where the alarm is to be given, *, a personal code, #. After having pressed the respective push buttons the alarm is switched on, for example after ten minutes, so that the person in question has sufficient time to leave the room. Switching off the alarm may take place by successively pressing: #, personal code, #. When a delay time of for example one or a few minutes is programmed before the alarm is activated, the person switching off the alarm has sufficient time to do so before his presence causes the alarm to go off.

The second embodiment, which is shown in Figure 2, is not in the form of a telephone, it is a very simple security device, which can be plugged into the wall socket of a telephone connection.

The security device according to the second embodiment is provided with a passive infrared detector (P.I.R.) 11 for detecting the presence of persons, standard telephone push

buttons 12, a light 13 for giving checking and/or other signals, a microphone/loudspeaker 14, and a plug 15, which is configured such that also a ^' second plug of a telephone can be connected.

Apart from the telephone function the second embodiment operates in the same manner as the first embodiment. An additional electric power supply may be present, for example in the form of batteries or in the form of an external connection foi the supply of electric current.

As already said before, the security devices shown are only to be considered as examples of possible embodiments.