The present invention relates to the field of the door locks and more particularly a control device for opening the lock of any, even armoured door as well as cast-iron covers of manholes and drains and metal or plastic open-air cabinets such as telephone exchange and electric energy cabins, etc.

Such cabins usually of plastic material are often damaged by vandalic acts directed above all to the parts which can be more easily damaged such as the door locks provided with common keyholes.

A first object of the present invention is to overcome such problem and to allow the locks to be opened by a portable electronic control device of small overall dimension and easy, reliable operation without the use of keys and then without the presence of keyholes . A second object of the invention is to provide an electromagnetic device installed in the cabinet which is capable of closing/opening the locks of the above- mentioned type and to operate without any power supply.

A third object of the invention is to provide a control device of the above-mentioned type having a programmable opening code as well as the capability of storing the progressive number indicating how many times the door has been opened as well as further desired data.

A fourth object of the invention is to provide a control device capable of being generally used for opening any door.

To sum up, according to a first preferred embodiment the invention includes two complementary parts : one part is formed of a portable device which is called herebelow "exciter", the other part is formed of a circuit so-called "receiver" and an actuator operated by the latter and to be installed within the cabin.

The operation principle is very easy: the portable device provided with its power supply can energize the circuit located inside the cabinet by bringing it close to the door or manhole, etc. of the cabinet not including any power supply so as to operate by electromagnetic interaction the electromechanical actuator which releases the lock.

Thus, the invention allows a lock to be opened without using any key for the necessary maintenance and/or any other operation by the authorised personnel and at the same time provides a ^' high security against unauthorised opening attempts.

A second embodiment of the invention having the same operation principle as the first embodiment based on the electromagnetic coupling of two resonant, transmitting and receiving circuits further provides an integrated circuit coder which processes a coded key for coding a recognition signal controlling the device, and a non-volatile memory for storing both the

recognition code and the number of actuation of the device as well as other data such as date and hour, i.e. a register which is increased by a unit whenever the door is opened by the electromagnetic releasing device and also stores the desired data.

Particularly in such second preferred embodiment the number of combinations generated by the integrated coder is equal to the number of binary combinations of 0 and 1 provided by sixteen so-called dip-switches. The present invention provides a so-called programmer formed of a logic processing unit or minicomputer with keyboard and display by which the coded recognition key can be entered in the integrated circuits of both the transmitter and the receiver for the coded information exchange.

The receiver, i.e. the fixed part of the whole apparatus, as mentioned above, is installed in the cabinet or generally in the closed room which has to be opened under control. Its installation and connections to the electromechanical opening device of the cabinet are the same as those of the preceding embodiment. The circuit of the receiver is passive. Actually it is energized by the electromagnetic interaction with the transmitter. It is a resonant circuit with a decoder recognizing the transmitted coded signal. Upon each actuation, the circuit stores in a non-volatile memory the occurrence of an opening and, by sum of events, the logic unit of the programmer will then read the number of openings of the cabinet as well as further data such as date and

hour of the openings.

The transmitter, i.e. the moving part of the whole apparatus, is very compact and has a long life battery capable of more than 1500 openings, as experimentally detected, due to the reduced power consumption of the transmitter. The latter is essentially formed of a signal generator which generates a sinusoidal carrier undistorted enough. The oscillator is excited at a predetermined frequency, for example 26 kHz, by the actuation of a button pushed by the user, thus connecting the circuit to the power supply and causing the lighting of a light emitting diode (LED) . The second embodiment of the invention also includes an integrated coder with a code of 16 bits stored in the non-volatile memory which generates a serial signal modulating the sinusoidal carrier. The envelope of the generated signals modulates the transmitted electromagnetic field exciting the receiver. The programmer, i.e. the characteristic component of such second embodiment, is formed of a logic unit with keyboard and display and is capable of programming the opening code which will then be transmitted as a serial coded signal to the decoder of the receiver via a cable connecting the transmitter and the receiver. In addition, the programmer can send a reading signal to the non-volatile memory of the receiver for reading the number of openings of the cabinet and other data. The circuits of the present apparatus includes discrete components which guarantee the maximum reliability. Particularly, the coded key was subjected

as an experiment to thermal treatment cycles in order to check the operation reliability as far as both the prohibitive environmental conditions and the stability in time. The circuit reacted positively to a thermal excursion of -20°C to +70°C.

Due to the minimum overall dimension of the fixed receiving unit, the latter can be located in a hole formed in the thickness of metal walls such as those of a manhole or an armoured door. This allows the described device to be also used with massive metal components.

A better understanding of the invention will ensue from the following detailed description with reference to the accompanying drawings which show by way of a non-limiting example two preferred embodiments. In the drawings:

Figure 1 is an elevation front view of a door under opened condition according to a first embodiment of the invention;

Figure 2 is a view of the upper side of the door of Figure 1;

Figure 3 is a partial view similar to Figure 1 of the door under closed condition;

Figures 4 and 5 are partial views sectioned along the plane A-A of Figure 3 of the locking system under

opened and closed conditions, respectively;

Figure 6 shows the portable device with the operating button according to a first embodiment;

Figures 7 and 8 show the diagrams of the "exciter" and the "receiver" of the first embodiment;

Figure 9 is the electric diagram of the transmitter generating coded signals according to a second embodiment;

Figure 10 is the electric diagram of the receiver receiving coded signals according to a second embodiment;

Figure 11 is the electric diagram of the programmer according to the second embodiment .

With reference to Figures 1 to 8 the operation principle of the electronic device is based, as already mentioned, on the interaction of an electromagnetic field generated by the portable device or "exciter" 7 and the electronic circuit of a "receiver" 9 located within the cabinet to be opened, for example, at the inner side of the door 11. Such interaction consists in supplying the circuit of receiver 9 with energy so that the cabinet door opens without needing any key or similar means commonly inserted into holes which are often occluded by

foreign bodies such as sticks, chewing gums, etc., or burnt and melted by gas lighters, matches etc. because of vandalic acts which in any case inhibit the opening of the lock from the outside and then cause the personnel to break the door in order to have access to the inner wiring.

In the first preferred embodiment which is now described the electronic parts essentially cause, for example through a relay, an engaging member 5 secured to the door to be disengaged from a projecting member 6 integral with the bolt 1 which moves substantially in its axial direction and rotates knob 10 provided with a projecting member 2. As can be seen from the Figures, bolt 1 lowers and brings its lower end 4 and the projecting member 2 of rotary knob 10 into engagement with the stationary parts of the cabinet, thus allowing the door to be closed. Such operation is carried out on the outer side of the door by rotating the knob 10 through its handle 8. In other words, once door 11 is brought near the closed position, knob 10 is rotated through handle 8 so that projecting members 2 and 4 are inserted into their housings and the linkage is brought to the closure position. It should be noted that such operation causes a return spring 3, for example of the helical type, to be tensioned so that knob 10 and bolt 1 tend to be brought to the opening position. In such first described embodiment, said return spring 3 has one end connected to door 11 and the other end connected to

bolt 1. Such operation also causes bolt 1 and then knob 1 and projecting members 2 and 4 to be locked due to the engagement of the already described projecting member 6 integral with bolt 1 and the engaging member 5 operated by a relay controlled by electronic circuit of receiver 9.

Door 11 is now locked in the closed position (Fig. 3) and the only way to be opened from the outside is to supply the circuit of receiver 9 with energy through the portable exciter 7.

With reference to Figure 8, receiver 9 essentially consists of a circuit tuned preferably to 25 kHz, a rectifier acting as a filter and a trigger switch feeding the slot relay only when the capacitor voltage reaches a value such as to guarantee the release of the slot.

The capacitance of the capacitor is calculated so as to be the right compromise between the need of ensuring the excitation of the slot and the need of having the minimum energy consumption.

For such reason, in order to charge the capacitor it is necessary that exciter 7 operates for some seconds, preferably 2-3 seconds. The energy of the magnetic field generated by the exciter is transmitted to winding L4 of the receiver coupled to capacitor C3 so that a current charging capacitor C4 is passed therein. The charging voltage rectified by diode D2 is transferred to a pair of Zener diodes D3, D4 which causes upon conduction the two transistors TR3 , TR4 biased by resistance R3 to

transfer the voltage of capacitor C4 to a relay (not shown in the Figure) which is connected across protection diode D5. The movement of the armature of such relay causes the bolt closing the door to be released.

Owing to its construction, the circuit of the receiver detects only electromagnetic fields of specific frequency and high intensity, the generation of which depends, for example, on a particular distribution of the lines of force. For such reasons, the susceptance to irradiated fields of any general type is excluded.

With reference to Figure 7, exciter 7 provided with its own power supply formed of cells or rechargeable battery (for example Ni-Cd battery) essentially consists of a normal high-efficiency oscillator preferably operating at the frequency of about 25 kHz and activated by a push-button 12. When pushed, button 12 causes the current of the battery to feed an oscillator formed of the two common-emitter coupled transistors TRI, TR2 and the windings LI and L2 connected to the bases and the collectors of the same transistors, respectively. The oscillation current induces to winding L3 the field which will be transferred to the receiver.

In such first embodiment the supply voltage is 9 Volt. The portable device 7 is contained in a plastic compact case easy to grip with only one hand and provided with a handle for facilitating the approach of the winding which generates the electromagnetic

field to the door.

The use of such exciter is very easy: it is sufficient to bring exciter 7 close to the door in front of receiver 9 and to push operating button 12 for a few seconds until the release of the lock. It should be noted that as the relay disengages members 5 and 6 from each other, bolt 1 is brought to the opening position by return spring 3, as shown in Figure 1. Advantageously, exciter 7 generates a sinusoidal wave and then does not produce harmonics and/or noise.

It is self-evident from the foregoing that the peculiar characteristic of the invention is that the circuit of receiver 9 operating the relay for unlocking the door has no power supply but is fed by the energy transmitted by the lines of force of the electromagnetic field generated by exciter 7. As well as overcoming the problems of the prior art, such characteristic avoids, on one hand, any maintenance of the cabinets regarding the replacement or the check of the battery and/or the power supply and, on the other hand, guarantees that only the personnel may open the door to have access to the inner wiring.

The arrangement of the components according to the first embodiment of the invention is clearly shown in

Figure 1 which illustrates the inner surface of a door hinged at its side 13.

A further advantage of the present invention is that all of the components forming the device can be easily installed in the currently used cabins so that a new

design is not needed.

With reference to Figures 9 to 11, in which a second embodiment of the invention is shown, the operation of the device is still based on the electromagnetic interaction between a field generated by a portable transmitter, the circuit diagram of which is shown in Fig. 9, and an induced circuit of the receiver shown in the circuit diagram of Fig. 10 and housed in the cabinet or room, the opening of which should be controlled. In this case, however, the electromagnetic coupling signal of both circuits is suitably coded and the circuits of the transmitter and the receiver are provided with coder and decoder, respectively.

The circuit of Fig. 9 showing the transmitter includes an exciter generally designated by 51 and essentially formed of an oscillator consisting of two common- emitter coupled transistors T51 and T52 and the windings L51 and L52 which are connected to resistances R52 and R51 at the bases of transistors T52 and T51, respectively, and to the power supply consisting of battery BT51 via a push-button control switch SW51. The emitters of the two transistors T51 and T52 are connected together to the collector of transistor T53, the base of which is connected through resistance R53 to the data output of the integrated coder generally designated by 52. Under rest conditions, the two transistors are disabled as T53 is switched off. When a proper voltage is applied between

resistance R53 and ground, transistor R53 is switched on and operates also transistors T51 and T52 which generate a square wave transformed into a sinusoidal signal by winding L51 and capacitor C51. The sinusoidal signal will control the opening of the cabinet door. The frequency of such signal is about 26 kHz and the voltage amplitude is about 25-45 Volt between collector and ground. The integrated coder 52 generates a serial coded signal which modulates transistors T51 and T52 through transistor T53 and then the sinusoidal signal controlling the opening of the cabinet door. Such code of 16 bits is stored in the non-volatile memory generally designated by 53. The clock of the transmitter is an integrated circuit indicated at 512.

The circuit of Fig. 10 showing the receiver includes a circuit tuned preferably at 26 kHz and consisting of a winding L53 and a capacitor C52, diode D51, capacitor C53 and the other components of the circuit having the same functions as those already described in the first embodiment.

The magnetic field generated by the transmitter induces an electromotive force to winding L53 which generates a current I charging electrolytic capacitor C53 through diode D51. Capacitor C52 has the function of rendering the circuit selective. The values of the components are such as to establish parallel resonance conditions at 26 kHz according to a preferred embodiment. The magnetic field of the transmitter modulated according to the selected code and induced

to winding L53 causes a modulated signal to be fed to capacitor C52 and to be used, after decoding, for controlling the unlocking mechanisms of the cabinet bolt to be released. The signal passing through resistance R54 is rectified by diodes D52 and D53, diode D52 also acting as limiter, and is fed to the base of transistor T54 through capacitor C54. The signal is first amplified and then its amplitude is limited. Transistor T54 inverts the signal which is fed through diode D54 to the base of transistor T55. Diode D54 detects only the decrease of the collector voltage of transistor T54 and rectifies the 26 kHz component of the carrier of the signal envelope. The residual carrier is suppressed by capacitor C55. Transistor T55 amplifies and inverts the signal for establishing the original phase of the signal from the resonant circuit formed of L53 and C52. The minimum duration of the pulse in the second preferred embodiment is 1,5-2 ms. By varying C55 it is possible to change the duration of the pulse up to about 0,5 ms. Resistances R55 and R56 along with resistances R57, R58 adjust the biasing of transistors T54 and T55. The signal at the collector of transistor T55 is then fed to the input of the integrated decoder, generally designated by 54, which detects and stores into the non-volatile memory 55 the received data, among which the progressive number of openings. If the coded signal is recognized by the integrated decoder 55, a pulse is generated and fed to the gate of the

controlled silicium diode D55. Diode D55 is enabled and causes the charge stored in capacitor C53 to be strongly discharged to the load formed of a not shown relay which is connected across diode D56 and controls the bolts of the cabinet to be unlocked. Simultaneously, decoder 54 feeds a coded signal to the non-volatile memory 55 which will increase by a unit the register storing the number of openings of the cabinet .

Fig. 11 shows the programmer including a keyboard 56, a microprocessor 57 for coding the opening code, a microprocessor 58 of the display, a display unit 59, a power supply 510, and a plug 511 for the connection to similar plugs of transmitter and receiver designated by the same numeral 510 in the respective Figures. Keyboard 56 consists of sixteen so-called dip-switches for selecting the sixteen-bit code and all of the desired data to be transferred to microprocessor 57 and then through microprocessor 58 to display unit 59 which shows code and data to the operator and through connecting plug 511 to both transmitter and receiver for programming the latter by the selected code. Of course, in addition to the writing of a code in the transmitter and the receiver of the above mentioned type, the programmer can also read an already selected code by assuming the reading state and following the same way as above but in the opposite direction. Similarly, the programmer can read the number of openings of the cabinet and other data stored in the

non-volatile memory of the receiver. The information is also shown on the screen of the display unit 59. The described device may be generally applied to all of the cabinets and/or rooms which can be closed and provided with rotary or slidable doors.

The present invention is described and illustrated according to two preferred embodiments thereof, however, it should be understood that anyone skilled in the art can make modification and/or equivalent replacement. For example, a device provided with a dual exciter capable of controlling one or more receivers (one for the opening, one for the closure) may be provided. These and other changes belong to the scope of the present invention as defined in the appended claims.