EP1783694A1

EP1783694A1 - Electronic lock comprising an automatic actuation system which uses a capacitive proximity sensor

Info

Publication number: EP1783694A1
Application number: EP04742069A
Authority: EP
Inventors: José Angel PEREZ LOPEZ; Aitor María AGUEDA QUESADA
Original assignee: Onity SL
Current assignee: Onity SL
Priority date: 2004-07-21
Filing date: 2004-07-21
Publication date: 2007-05-09
Anticipated expiration: 2024-07-21
Also published as: DE602004031469D1; ES2360857T3; WO2006021592A1; ATE498876T1; EP1783694B1

Abstract

The invention relates to a low-power-consumption electronic proximity lock comprising an automatic actuation system which measures variations in the capacitance of the environment of a plate (3). According to the invention, the aforementioned plate serves as a proximity sensor which, together with the environment thereof and an earth connection, forms a dummy capacitor, having a capacitance which varies depending on the proximity of a body. In this way, upon detection of the proximity of a body, the automatic actuation system activates a contact less communication system which emits a communication signal, e.g. a radio frequency signal, which is intended to establish a data exchange with a card. When a card is within proximity of, and corresponds to, the lock, the communication system transmits an order to the lock control system and performs the appropriate actions in accordance with the type of data exchanged.

Description

Invention field

The new electronic proximity lock referred to by this invention is orientated to electronic lock applications in which the lock is an electronic stand-alone device, meaning that it is fed by batteries and not connected to an electrical supply, or is a device in which low energy consumption is required and the key with which this lock is operated is a non contact proximity key, that can be a card, a key fob, or in general any object that incorporates technologies for the exchange of information between electronic devices without any physical contact between them. For this the lock itself must also incorporate the necessary electronics so that this information exchange without contact can occur and a low consumption activation system of this communication electronics to reduce the elevated energy consumption that would be required to maintain the lock constantly in communication. At the same time, the solution referred to by this invention can be integrated into any other electronically controlled device that, like the electronic lock, is stand-alone electronically or that without being so searches for a minimum energy consumption and is operated by proximity of a non contact proximity key, such as safety boxes, encoders, wall card readers, etc. These devices are usually intended to equip, for example, rooms in hotels, cruises, government buildings, military buildings, universities and in general any premises used by a wide variety of users with timely access rights.

Prior art

Within the electronic locks field, the concept of electronic proximity lock work has developed in various prior arts, clearly differentiated and in the majority of occasions it has been directly related with the use as cards as the key element. The first electronic proximity lock concepts, such as that described in patent US4717816 , understand the term of proximity, covering exclusively the reading element, meaning, the lock is not operated by the proximity of the card but by reading the card, in this case magnetically coded, is performed without the need of physical contact between the card and the reader on the lock but always with the necessity of the card being inserted into the reader slot or, in the most general term, for the card to be positioned in a precise manner on the lock reader. In the quoted patent an electronic lock is described that has a magnetic reader with three heads able to detect a code written on a card by means of three magnetic strips.
Subsequent applications of electronic proximity lock work widen this proximity concept to its more general interpretation, meaning, that the key card or the key element that must interact with the lock must not forcibly be inserted in a lock slot or in a precise position on a reader head as in the previous case, but that can operate by an external proximity of the key card to the lock without strict positioning requirements in respect to the lock.
This new electronic proximity lock work concept is based on the application of exchange technologies of important volumes of information without contact between one electronic component, such as a lock, a key or card that have storage or information exchange elements such as the cards with proximity chips. These technologies allow an exchange of information between these two elements by the mere proximity between said elements, for example by means of radio frequency, and therefore does not require the insertion of the card in a slot nor specially precise positioning of it on a determined reader, the only necessary and sufficient condition is the proximity and the distance to which this type of communication can be made depends, among other facts, on the transmitting power of the electronic device that interacts with the proximity cards.
To date, diverse inventions have been created that respond to the previous evolution and that integrate as one of its differentiating parts the denominated automatic activation system, whose purpose is to reduce the consumption derived from maintaining the communications system constantly transmitting a signal. An initial approach is that described in patent ES2112152(A1 ), in which a mechanical type of automatic activation system is described. It is a stand-alone electronic lock fed by batteries that has a reader unit for proximity chip cards by means of electromagnetic waves that is lethargic in a state of minimum consumption. In the presentation manure of the chip card the user must push on some of the surfaces of the lock which is connected to a switch, which thanks to this pressure connects to the chip card reader unit feed activating it and allowing at that moment the lecture of the card without any contact between the card and the lock.
Inventions have subsequently been developed that do not require any contact for the activation of the communication system. This is the case of the inventions described in patent EP1026617 (A1) which consists in an electronic lock with automatic activation systems without contact using infrared detection systems, optical barrier or composed by transmitter-receiver of a ray that reflects on the card. These systems also achieve a low total consumption of the electronic lock making the communication system transmit only in case it is potentially necessary since the consumption of the activation system proposed is less than the communication system consumption.
Some commercial solutions, of which no remarkable written references exist, are based on substituting the presence detection for the automatic activation for an activation, programming the communication system in function of the expected frequency of use of the lock in such a manner that, for example, if a user has recently opened a door, the time between a communication system switch on and the next is more extensive than after various hours of lock inactivity in which the arrival of a possible user is expected.
The most recent advances in this field are described in patent JP2001055852 . It is an electronic proximity lock equipped with an automatic activation system that has an oscillation circuit with a determined frequency and resonant circuit that causes a resonance to a harmonic of a determined higher number of times than the oscillation frequency. When a body moves in the proximity of the detection electrode the resonance state varies due to the electrostatic capacity that is generated between the body that has come near and the detection electrode, generating voltage that indicates this proximity and that activates the communication circuit. This way, the overall consumption of the lock is very low, the lock operation does not require contacts not even for automatic switch-on. This invention specifically exploits a physical phenomenon by which the environmental capacitance varies with the presence of a body, that at the same time produces a variation in the variation of the resonance, but the differentiating element is the mentioned change of electrostatic capacity.
In this sense patent US6362632 proposes a system to measure the environmental capacitance variation when there is proximity of an object.. Despite it being a patent not directly related with an electronic lock, the invention consists in using a circuit with two switches whose purpose is to charge a reference condenser with a known capacitance and stable in time, by means of consecutive charges and discharges of a plaque that at the same time acts as a sensor. The first switch allows the sensor to connect to a determined voltage and the second switch connects the plaque to the reference condenser. Stemming from an initial situation in which the both the sensor as well as the condenser are discharged or with a known charge, if the first switch is short circuited, the sensor will adopt a charge in proportion to the voltage and to the capacitance at that precise moment. If after doing this the first switch opens and the second switch closes, the charge required by the sensor will be transferred to the reference condenser, generating a voltage that will be a function of its already known capacitance and the transferred charge, giving this an idea of the capacitance of the sensor from which the charge was transferred from. This type of detection systems have not been applied to date to an electronic lock combined with a communications system.
Throughout all of this description of the prior art, automatic activation system and non contact communications system for cards are always joined as two integral parts of an automatic activation and communications module. In fact, the principals of a mechanical or optical automatic activation combined with a proximity communications system has been incorporated to other stand-alone requirements similar to those of an electronic lock, as can be the case for a safety box in a hotel room operated by a proximity card. In this sense, there are commercial solutions available without noteworthy documented references, that combine automatic activation and communication as a single module to be incorporated in any device that requires it, but as mentioned in the previous paragraph, all these modules are based on the mechanical or optical detection principals and not in principals such as the detection of environmental capacitance detection in respect to a reference condenser.

Explanation of the invention

The present invention refers to a new electronic proximity lock and to the automatic activation and proximity communications module that characterizes it. It deals with a lock operated by the proximity with a key element, hereinafter a card, in which the exchange of information between the lock and the card is performed without the necessity of any contact between them and without the necessity of the card being inserted in any slot in the lock or positioned in any manner on the card reader.
The technical problem which we intend to overcome with the present invention is related with the current communication technological limitations that allow this type of communications without contact between the lock and card, such as for example the radiofrequency proximity card reader systems. These communication technologies require an important energy consumption of the reader device so that it creates around itself a field which excites the electronics incorporated in the proximity card and it can transmit the corresponding signal and that way perform the information exchange between card and device.
The majority of the current electronic locks, due to economic viability motives, are stand-alone devices from an energy point of view and are usually fed by conventional batteries. By incorporating proximity card technologies in the stand-alone electronic locks this elevated energy consumption by the proximity communications system, becomes critical for the lock viability. So that when the user nears the lock and it responds opening as the card carried by the user corresponds with the lock, the communication system must be functioning. Since it is impossible to create a precise pattern of the instant in which said user is going to come near said lock with the intention of opening it, since this is unpredictable, in an initial approach the communication system must remain permanently transmitting to detect any card that comes near the lock. From an energy point of view this would make the lock's battery life, and therefore it's autonomy, excessively reduced and would require a substitution or a recharge of the batteries in the lock excessively frequently, generating a cost and a maintenance complexity that make this solution non viable. To intend to have the batteries permanently fed by the conventional electrical current supposes and excessively high extra cost in the electrical installation for the applications in which electronic locks are usually used, such as hotels, and even in the case that the lock is connected to the electrical current, the energy consumption of maintaining the communication system constantly transmitting a signal would be a high energy cost, not very efficient and not very profitable. Another solution is to program communication system activations, which reduces the total consumption but the features that are given to the lock user will depend on how closely fitted the activation pattern of the communication system is to the usage needs of the lock, with which if special features are required the communication system must be activated frequently, increasing the consumption of energy, and if the reduction of consumption is wanted a user must wait for the activation of the communication system to open the lock. Therefore, the only solution for this limitation is to incorporate in the lock a low consumption proximity detection system for the automatic activation of the communication system, so that the lock can detect the proximity of a body or object at all times but maintaining residual electric consumption and can activate the communications system, with an elevated energy consumption, only when it is potentially necessary. Also, these systems must allow the detection and the automatic activation on such a rapid manner that the features offered to the user are not diminished, that means that the user does not perceive any delay in the operation of the lock due to the incorporation of the automatic activation system. With this solution, the autonomy of the electronic proximity locks is adequate so that their installation is technically and economically viable in the application to which the electronic proximity lock is destined.
Just as it has been described in the prior art, to date different solutions have been given to the automatic activation of electronic proximity locks, highlighting the automatic activation by mechanical, optical or resonance means. The proximity electronic lock and the automatic activation and proximity communications module of the present invention widen this range on solutions through proximity detection, and the posterior automatic activation of the communications system, stemming from the measurement of variations in the capacitance of the environment next to the lock.
The system that uses the invention to measure the variations of capacitance of the environment, and therefore for the detection of the proximity of a body or object to the lock or the automatic activation and proximity communications module, is known as the charging pump. Figure 1 shows the theoretical circuit on which the charging pump is based. Its operation is based on the alternative conmutation between two switches (1) and (2). When switch (1) is short circuited and switch (2) is kept open, a conducting plaque (3) connects which acts as a predefined voltage sensor (VCC). This plaque (3) creates together with the proximity environment and grounds a fictitious capacitance (CX) condenser (4). This capacitance (CX) is variable and depends on the conditions of the environment next the plaque (3) and therefore, the proximity of an object or body to the plaque would produce a variation in (CX) in respect to the situation in which there is no proximity of a body or object to the plaque (3).
Therefore, when short circuiting the switch(1) keeping switch (2) open, the plaque (3) will charge with a charge (qx1) in direct function to the capacitance (CX) in said instant. Next, switch (1) opens and switch (2) is short circuited. At this moment charge (qx1) acquired by the fictitious condenser (4) is transferred to a reference condenser (5) connected to earth and with known capacitance and stable in time (CP). If afterwards switch (2) is open and switch (1) is short circuited, the reference condenser (5) keeps the charge (qx1), while the plaque (3) recharges with a charge (qx2) that will be in function of the capacitance (CX) of the fictitious condenser (4) at the instant of the second manoeuvre.
Continuing with this process, repeating a number (N1) of times the previous charge cycle without discharging the reference condenser (5), the reference condenser (5) will have a total charge that will be the sum of all the partial charges transferred from the plaques (3) in the (N1) charge cycles, and generates tension (V1) among its terminals that will be in function to the total charge that has been transferred from the plaque (3). When comparing the tension (V1) with a known reference tension (VREF) an environmental capacitance measure will be obtained during the execution of the cycle. According to what has been said so far, if (VREF) is predetermined as the tension that would be generated by the condenser when charged during (N1) charge cycles without the proximity of any body or object to the plaque (3), the variation of tension (V1) in respect to (VREF) will determine for example the proximity or not of a body or object during the execution of (N1) cycles.
Figure 2 shows another construction of the theoretical circuit with the same elements as in figure 1 but with a provision nearer to that required by the present invention. With the provision of switch (2) between the reference condenser (5) and ground we achieve situation said reference condenser (5) between the switches (1) and (2), facilitating the incorporation of a manoeuvre system for the switches as for example a microcontroller (6) as is shown in figure 3. The incorporation of this microcontroller (6) supplies a simple solution, of great flexibility and with great control capabilities for the execution of the charging pump cycles previously described. At the same time the microcontroller (6) allows the switch operations to be performed at a very high speed, very superior to the normal approximation time of a user with the lock card, in such a manner that the user does not perceive and delay in the operation of the lock when the complete process is processed.
The incorporation of this microcontroller (6) allows a more optimized application of the previous charging pump system, designed to measure the environmental capacitance, adapting it to its application to the detection of the proximity of a body or object to the lock in an efficient, safe and stable manner. The system improvement of the charging pump incorporated to the present invention consists in a new method or algorithm as shown in figure 4 that executed by the microcontroller (6) offers the lock response features to the proximity of a user and to the global consumption of the proximity lock that improves the prior art of this technical field..Figure 4 shows the final construction of the low consumption automatic activation system by means of detection of the variations in environmental capacitance of the present invention. It includes two protection diodes (7) and (8) and three resistance (9), (10) and (11) for the adjustment of the currents and tensions n the circuit.
Figure 5 shows a summary of the method used by the present invention for the detection of proximity using a modified principal of the charging pump previously described. As commented, said method consists in an algorithm executed by a microcontroller (6) on the modified charging pump circuit shown in figure 4. In this process two sub processes intervene denominated as:

Charge cycle, which is the manoeuvre in which the charge is produced in the plaque (3) and its posterior discharge, transferring the charge acquired to the reference condenser (5). As mentioned before, the amount of the charge transferred in each charge cycle will depend on the environmental capacitance of the plaque (3).
Complete charge process, which is the repetition of consecutive charge cycles until the tension generated between the terminals in the reference condenser (5) equals or surpasses the tension threshold (V2). As collary to the previous process, the number of charge cycles involved in each complete charge process will depend on the environmental capacitance while performing the complete charge process. After every complete charge process the reference condenser (5) discharges to an initial known charge that can be for example null.

The method starts with the positioning of the automatic activation system in an initial position (B1) as a system restart mode and the system calibration (B2) that is produced for example in the first installation of the lock. The calibration of the system is not only produced during the restart but also in the (B7) and (B9) phases of the process, in which the complete system is recalibrated. In these calibrations value is given to the comparison variables of the measured signal and the reference tensions that the system uses, and both the fictitious condenser (4) as well as the reference condenser (5) are discharged to an initial status that could constitute for example in both condensers being completely discharged. The comparison variables and the reference tensions that give value to these calibrations are:

Tension (VCC), or the fixed tension to which the plaque charges are made (3).
Trigger threshold (N2), or the number of charge cycles necessary for the reference condenser (5) to generate in its terminals tension which is higher or equal to the tension threshold (V2), with the condition that there is no proximity to the plaque (3) by any body or object which is not a part of the lock.
Tension threshold (V2), or the tension generated in the terminals of the reference condenser (5) after performing a number of charge cycles coinciding with the trigger threshold (N2), with the condition that there is no proximity to the plaque (3) by any body or object which is not a part of the lock.
Counter value (CONT1), that in the calibration and after each complete charge process is positioned to zero, and is the variable that counts the number of charge cycles performed in each complete charge process, in such a manner that each time that a charge cycle is performed the value of the counter (CONT1) increases by one unit.
Sensitivity (S), or the value of the difference between the trigger threshold (N2) and the counter value (CONT1) after each complete charge process, which means a possible approximation of a body or object to the plaque (3).
Number of activation cycles (N3), or the number of consecutive times that the counter value (CONT1) must vary in respect to the trigger threshold (N2), and its difference must surpass the sensitivity (S), so that this unequivocally means the proximity of a body or object.
Counter value (CONT2), that in the calibration is positioned to zero, and is the variable that counts the number of consecutive complete charge processes in which the value of the counter (CONT1) has varied in respect to the trigger threshold (N2) and its difference has surpasses the sensitivity (S).

After this initial adjustment, the system executes a first measurement (B3) of the environmental capacitance by means of charge cycles. In this measure the fictitious condenser (4) initially proceeds to be discharged as well as the reference condenser (5) and to position the counter value (CONT1) to zero. After this charge it proceeds to the performance of the consecutive charge cycles. In each charge cycle, by means of a conmutation of the microcontroller (6) the plaque (3) is charged connecting it to a fixed tension (VCC) while the reference condenser (5) is connected. Afterwards, the microcontroller (6) opens the plaque (3) conmutation feed and closes a discharge circuit to charge the reference condenser (5) with the recently acquired charge for the plaque (3). This charge is stored in the reference condenser (5) which disconnects from the plaque (3). With this a tension increase is provoked among the terminals in the reference condenser (5) proportionate to the capacitance if the fictitious condenser (4) made up by the plaque (3) and its environment close to earth, which is dependent of the environmental conditions and the proximity or not of a body or objects. After this charge the previous counter value (CONT1) is increased by one unit and the tension between the terminals in the reference condenser (5) is measured to see if it equals or surpasses the tension threshold (V2). If the tension in the terminals of the reference condenser (5) does not surpass the tension threshold (V2) the charge cycle is repeated until the tension in the terminals of the reference condenser (5) equals or surpasses the tension threshold (V2).
If the tension in the terminals of the reference condenser (5) equals or surpasses the tension threshold (V2), a complete charge process has been performed and we pass on to the comparison (B4) of the current counter value of the charge cycles (CONT1) and to the trigger threshold (N2). At this point the method varies lightly in function of the effect expected by the proximity of the body in the environmental capacitance of the plaque (3).
In the majority of cases, the proximity of a body to the plaque (3) creates an increase in the capacitation of the fictitious condenser (4) but the existence of determined materials has been confirmed, some of them used as support for the proximity chips that create a decrease in the environmental capacitance with their proximity to the plaque (3). The incorporation of the microcontroller (6) in the present invention allows the modification of the method applied in function of the effect expected by the proximity of the proximity support chip without more than varying the algorithm used. This difference of algorithm consists basically in that, in the comparisons of measures performed of the current counter value (CONT1) in respect to the trigger threshold (N2), the value which means possible proximity of a body or object is higher or lower than the trigger threshold (N2). Both cases are contemplated separately in the claims but to the effects of the description of the invention we only consider the case in which the proximity of a body or object generates an increase in the capacitation of the fictitious condenser (4) and therefore, the current counter value (CONT1) is less than the trigger threshold (N2) when there is proximity.
Continuing, after the last clarification, at the comparison point (B4) the current counter value (CONT1) and the trigger threshold (N2) after each complete charge process, in case that the current counter value (CONT1) is higher to the trigger threshold (N2) the capacitation of the fictitious condenser (4) is less than its capacitation without presence of a body or object, therefore there is no proximity of any body or object to the plaque (3) and the communications system (B6) must not activate. In all instances it is possible that the whether conditions, humidity, electrostatic charge have varied and this has varied the environmental capacitation, therefore the values of the comparison variables described in the restart (B1) and calibration (B2) process must be recalibrated (B7) in function to the new situation given by the last complete variation measurement of the environmental capacitation. After this calibration the moment in which the new measurement process of the environmental capacitation (B11) variation is initiated is determined and the automatic activation system (B12) is deactivated, that after the pre-programmed time period reactivates (B13). After this activation the communication circuit is checked to see if it is activated or not (B14). In case it continues to be activated, the automatic activation system considers that the last communication process has not finalized and returns to program the next activation (B11). In case the communications circuit is not activated the process restarts from the environmental capacitance measure (B3).
In case the current counter value (CONT1) is less than the trigger threshold (N2) after the complete charge process, these means that the fictitious condenser (4) capacity has been increased and that therefore it is possible that there is proximity of a body or object to the plaque (3). In any case this first measurement is not conclusive since the increase of the capacitance of the fictitious condenser (4) can have occurred by temperature variations, humidity or electrostatic charge of the environment next to the plaque (3). Therefore in this case it proceeds to the comparison (B5) of the difference between the trigger threshold (N2) and the current counter value (CONT1) in respect to the sensitivity (S) If the difference does not surpass the sensitivity (S) an increase in capacitance has occurred not related with the proximity of a body or object to the plaque (3), and therefore the communication system (B6) must not activate, but a change has occurred in the environmental conditions and therefore the values must be recalibrated (B7) of the comparison variables describe in the restart (B1) and calibration (B2) process to the new situation given by the last complete measurement of variation of the environmental capacitance. After this calibration the moment in which the new measurement process of the environmental capacitation (B11) variation is initiated is determined and the automatic activation system (B12) is deactivated, that after the pre-programmed time period reactivates (B13). After this activation the communication circuit is checked to see if it is activated or not (B14). In case it continues to be activated, the automatic activation system considers that the last communication process has not finalized and returns to program the next activation (B11). In case the communications circuit is not activated the process restarts from the environmental capacitance measure (B3).
If the difference between the counter value (CONT1) and the trigger threshold (N2) after the complete charge process is higher to the sensitivity (S) there is a second proximity indication of a body or object to the plaque (3) but with a single measurement also does not confirm the proximity since it could be due to internal feed or electronically errors. Therefore, the counter value is increased by one unit (CONT2) and (B8) the complete charge and comparison process is repeated from (B3) to (B5) until one of the following three cases occurs:

That in one of the complete charge processes the value of the counter (CONT1) is higher than the trigger threshold (N2) when the tension threshold (V2) has been surpassed, with which the environmental capacitance has decreased and therefore there is no proximity.
That in one of the complete charge processes the difference between the trigger threshold (N2) and the current value of the counter (CONT1) is lower to the sensitivity (S) when the value of the counter (CONT1) is lower than the trigger threshold (N2) with which the environmental capacitance is not due to any proximity.
That the actual value (CONT2) equals the number of activation cycles (N3), with which the increase in capacitance detected is unequivocally due to the proximity of a body or object to the plaque (3). In this case the situation of the environment due to the proximity of an object has been modified that could be a user of the lock with a card or not, it could be for example an object that has stuck to the lock or a decorative element that has been placed close to the door. In case it is a nearby body or object that is not going to be removed in a brief time lapse, a situation will be produced in which the system will be constantly sensing continuous proximity , keeping the communication circuit active and therefore consuming energy and drastically reducing the autonomy of the lock. To avoid this, the first calibration (B9) of the values of the comparison variables described in the restart (B1) and calibration (B2) process to the new situation given by the last complete variation measurement of the environmental capacitation, that will correspond to the values with the proximity of a body or object.. These values, in case the proximity is of a user that moves away from the lock after its normal operation will readjust to similar values to the initial ones in later variation of the environmental capacitance measurement process. After this calibration the moment in which the new measurement process of the environmental capacitation (B11) variation is initiated is determined and the automatic activation system (B12) is deactivated, that after the pre-programmed time period reactivates (B13). After this activation the communication circuit is checked to see if it is activated or not (B14). In case it continues to be activated, the automatic activation system considers that the last communication process has not finalized and returns to program the next activation (B11). In case the communications circuit is not activated the process restarts from the environmental capacitance measure (B3).

Meanwhile both the recently activated communication system is transmitting a signal, without being disturbed by the field that could be created by the automatic activation system plaque (30) since it is inactive, in search of a card or key object that incorporates the communication technology compatible with the communications system integrated in the automatic activation and communications module of the lock of the present invention. If in the proximity of the lock there does not exist said card or key object, after a set time the communication system will return to inactive until the automatic activation system detects a new proximity. On the other hand, if said key object is in the proximity of the lock, the communication system will exchange information with this element and in case of corresponding with the key object that corresponds with the lock, the communication circuit will transmit a signal to the lock's control circuit, which will correspond by performing and operation corresponding to the nature of the information exchanged, for example by opening the lock.
At the same time, the present invention includes a solution to one of the basic problems that affect the combination of an automatic activation system based in capacitive principals and a communication system without contact such as radio frequency. This problem is the distortion of the communications electromagnetic field that can produce by the presence of a conductive plaque (3) whose mission is to serve as a sensor to detect the capacitance variations. By definition, this plaque (3) must have sufficient conductive surface to be able to create with the environment a fictitious condenser (4). Also, by definition, by submitting the conductive plaque (3) to an electromagnetic field, a series of internal parasite currents will be generated in it that will generate a second electromagnetic field that oppose the electromagnetic field that generates it, distorting it. This is precisely the case in which the present invention finds itself, since we must integrate a conductive plaque (3) and an antenna (12) that generates a communication electromagnetic field in a reduced space due to instability and viability of the electronic lock as shown in figure 6. The present invention solves the present problems in two fronts:

The first, by means of the work method previously described, in which at no time is the parallel functioning of the automatic activation system and the communication system permitted in such a manner that the plaque (3) does not receive charge from the tension (VCC) is the communication system is in operation.
The second, by means of the incorporating of a plaque(3) whose surface is divided into thing conductive nerves, close to a millimetre of width, electronically interconnected between themselves by means of a common nerve conductor also thin so that as a set they make up a metallic surface sufficient for the plaque (3) to have the adequate features for its use as a captive sensor and at the same time offers a great resistance to the generating of internal closed circuits that promote the generation of internal parasite currents when submitting the plaque (3) to the electromagnetic field generated by the communications antennae (12). In this manner the parasite currents generated are minimized and also their negative effect in the communication field, making it effective even in case the plaque (3) is located in front of the antennae (12) as shown in figure 6. This circumstance is very dramatic in those low power devices feed by conventional batteries, which is precisely the field in which the present invention falls.

In respect to the advantages of the present invention in respect to the prior art, if the features of the invention are compared in respect to those offered by the locks that incorporate systems of mechanical activation, the main advantage is that, in the case of the mechanical systems a first contact is always required to activate the communication circuit and the present invention does not require contact at any time. Furthermore, the existence of mobile parts for the mechanical activation is an origin of possible faults or sabotage, for example inserting strange elements into the unavoidable slots of the mechanical system, that with the present invention are saved by the non need for contact.
In respect to the locks with optical automatic activation system, despite that from the functionality point of view these solutions already offer non contact lock operation, they have a series of disadvantages that make them improvable. The main disadvantages of these systems are due to the automatic activation system detection principal itself. It deals with systems that require optical signs to be transmitted, therefore they depend on the cleaning of the transmitting or receiving surface which is essential for its function, making them specially sensitive to sabotage, and on the other hand, the transmission field of the optical signal must be perfectly adjusted in position and angle in the space since an non precise adjustment can produce that the swept field is excessive wide, detecting any type of presence with or without the intention of interacting with the lock and producing a higher lock consumption, on the contrary it can be to narrow impeding the correct function, in such a manner that they require a very precise assembly and a frequent and costly maintenance. In the case of the present invention these problems are solved since the detection is performed without the need of transmitting any optical signal and in case of sabotage, for example by sticking a substance on the reader, the automatic activation system itself is the one that adapts itself to the variables of the new situation and continues to function. Finally the proximity capacitive detection requires less energy consumption so that the autonomy of the lock for the batteries is higher in the present invention.
In respect to the solutions with programmed activation of the communication system, despite that these solutions improve the weak points of the mechanical and optical solutions, it completely depends in the success of the activation programming of the communication system achieve a good relationship between response time and features offered to the user, so that they result in a higher consumption and a better autonomy of the lock, in this way missing the basic objective that motivates the development of the solution. On the other hand, the fact that the automatic activation and communications and the proximity lock of the present invention incorporate a programming function of the moments in which the proximity capacitive detection system performs the measurement of the environmental capacity, makes it possible to incorporate to its algorithm the same functions as the solution with programmed activation of the communication system, but with the difference that what is activated is the low consumption automatic activation system and not the increased energy consumption communication system.
Finally, the main advantage contributed by the present invention in respect to the solutions based in oscillation and resonance circuits from the variation of the environmental capacity, is that the main detection used is simpler and the use of a microcontroller (6) in the circuit widely amplifies the flexibility of the device and its control capacity, improving the lock features and reducing at the same time the possible error focuses when simplifying the necessary circuits. At the same time, in these solutions we have not dealt with the problematic generated by the introduction of a conductive plaque (3) as a sensor in the same device as the antennae that is required by the communication system and in the present invention more than solves this problem.

Explanation of the figures

Figure 1 shows a theoretical circuit that operates as a charging pump destined for the measurement of the environmental capacitance of the plaque (3).
Figure 2 shows an evolution of the circuit with the same functionality as in figure 1 but with a relocation of the switch (2) more in agreement with the application of the present invention.
Figure 3 shows a charging pump circuit commanded by a microcontroller (6) with the same functionality as the circuits in figures 1 and 2.
Figure 4 shows the basic system of the automatic activation system by means of detection of the variations in environmental capacitance of the present invention.
Figure 5 shows the diagram of the operations of the method followed by the present invention to determine the proximity of a body by variation of the environmental capacitance of a plaque (3)..
Figure 6 shows a general diagram of the main construction elements and the internal elements of the proximity lock of the present invention.
Figure 7 shows the proximity (21) and communication (23) detection areas.
Figure 8 shows the main angles to keep in mind for the plaque (3) placement in function to the most probable approximation angle of the card (22)
Figure 9 shows the main external distances to the lock to keep in mind for its operation.

In these figures the following references are indicated:

VCC.- Fixed tension by which the plaque is charged (3).
VREF - Reference tension as comparison with the condenser (5) tension
CX. Variable capacitance of the fictitious condenser (4)
CP. Known capacitance of the reference condenser (5)

1.- First switch of the charging pump circuit
2.- Second switch of the charging pump circuit
3.- Plaque that with its environment and grounding creates the fictitious condenser (4).
4.- Fictitious condenser created by the plaque (3), its environment and grounding.
5.- Reference condenser of known capacitance
6.- Microcontroller that commands the automatic activation by capacitive variation
7.- First protection diode of the automatic activation system of the invention
8.- Second protection diode of the automatic activation system of the invention
9.- First adjustment resistance of the automatic activation system of the invention
10.- Second adjustment resistance of the automatic activation system of the invention
11.- Third adjustment resistance of the automatic activation system of the invention
12.- Antenna from the communication system of the invention
13.- Non metallic material part that covers the plaque (3).
14.- External metallic casing of the electronic proximity lock
15.- Handle of the electronic proximity lock
16.- Plaque that supports the communications antenna and plaque (3).
17.- Plaque that supports the automatic activation and communication circuits.
18.- Location of the control system of the proximity lock operations
19.- Location of the electromechanical elements of the proximity lock
20.- Location of the batteries that feed the proximity lock
21.- Field for detecting effective proximity.
22.- Proximity card
23.- Field for effective communication with card

B1.- Restart event of the automatic activation system
B2.- Calibration action of the automatic activation comparison variables
B3.- Action of measurement of the variation of the environmental capacitance of the plaque (3)
B4.- Comparison of the measurement in respect to the trigger threshold (N2)
B5.- Comparison of the difference between (N2) and the measurement in respect to the sensitivity (S)
B6.- Action of non activation of the communication system.
B7.- Recalibration action of the automatic activation comparison variables
B8.- Comparison of the number of consecutive measures that indicate proximity.
B9.- Recalibration action of the automatic activation comparison variables
B10.- Action of activation of the communication system.
B11.- Programming action of the following execution of the automatic activation system
B12.- Deactivation event of the automatic activation system
B13.- Activation event of the automatic activation system
B14.- Comparison of the activity situation of the communication system.
α- Vertical positioning angle of the plaque (3)
p- Probably approach angle of the card in respect to the vertical plaque.
D1.- Distance of the plaque (3) in respect to the metallic lock carcass.
D2.- Nominal distance of the proximity card for the operation of the lock

Exposure of a preferential performance

Figure 6 shows the exterior aspect and the general elements contained in a preferential performance of the electronic proximity lock of the present innovation. In the exterior of the preferential performance the following are highlighted, the metallic carcass of the electronic proximity lock (14), the handle on the proximity lock (15) and a non metallic element (13), for example in plastic, that covers the plaque (3) that acts as a sensor element. This non metallic (13) cover allows the communication field created by the lock communications system is not screened by the metallic carcass (14) of the proximity lock.
In the interior of the lock the first highlighted item is the conductive plaque (3) by proximity sensor by variation of the environmental capacitance and the antenna of the communications system (12). Plaque (3) and antenna (12) are physically found assembled on a single support plaque (16) or PCB, one on each face of said support plaque (16), and with the plaque (3) situated on its most external face. Due to the special surface of the plaque (3) in parallel nerves approximately one millimetre wide with a transversal nerve that electronically connects them, the communications field created by the antenna (12) when the communications system is active is not distorted when passing through the plaque (3) and the whole group can adopt its maximum compactness reducing the space necessary in the lock and therefore reducing its total size. This group of plaque (3), antenna (12) and common support plaque (16) are fixed to a second plaque (17) that houses at the same time, the microcontroller (6) necessary for the automatic activation, the additional electronics necessary for the automatic activation circuit and the necessary electronics for the communication system.
At the same time, it is worth noting the location of the general operation control (18) electronics common to all the electronic locks whether of proximity or not, whose function is the execution of the actions adequate to the nature of the information received from the key card, for example open the lock, the location of the electromechanical elements (19) of the lock and the location is the batteries (20) that supply the energy necessary for the lock to be energy autonomous.
With this performance, in figure 7 a transversal cut is shown of the top part of the electronic proximity lock that houses the proximity detection plaque (3) and the antenna of the communications system (12). In figure 7 effective area for the detection of proximity(21), a possible approach by a proximity card)22) and the effective communication areas (23) with the proximity card. As shown in figure 7, these effective detection (21) and communication (23) areas are concentrated around the area in which the electronic proximity lock does not have external metallic carcass (14), but a non metallic covering (13), for example plastic. In the rest of the areas around the metallic carcass (14), said carcass produces a screening effect on the detection and communication fields therefore the user must approach the area covered by plastic (13) with the card.. In said covering (13) indication signs are recorded of this mode of interacting with the lock. However, the screening of the communication field by the metallic carcass (14) produces a desirable effect in the back part of the lock. This back part usually corresponds with the interior part of the room closed by the electronic lock. Id this screening did not exist on the back part, there would also exist an effective communication area in the interior of the room, with the subsequent risk of the lock opening without intending to.
As seen in figure 7, the effective communication area is larger than the proximity detection effective area. This is done like this so that, in the possibility that the user lightly moves the card (22) on the proximity of the lock and he communications field is able to interact with the card even if the movement is of lightly leaving after the proximity detection. In general terms, the card (22) can be read in any position it is in within the effective communication areas (23), even though a parallel approach between the surface of the card (22) and the surface of the non metallic carcass (13) of the approach with the largest guarantee of function of the lock.
In this respect figure 8 is shown with a transversal cut on the top part of the electronic proximity lock that houses the proximity detection plaque (3) and the antenna of the communications system (12). In this figure two angles are highlighted: angle (α) for the positioning of the plaque (3) and the antenna (12) located in the same support plaque (16) in respect to the vertical, and angle (β) which is the probable angle of approach of the proximity card in respect to the vertical.
We have seen that the lecture of the proximity card by the communication system integrated in the electronic lock is better when there is parallelism between the antenna (12) and the card (22). Therefore, once the value has been determined of angle (p) most probable in respect to the vertical in which the user approached the proximity card (22) to the non metallic cover (13) that covers the proximity detection plaque (3) and the antenna (12), the angle (p) with which the group made up of by the proximity sensor group (3), antenna (12) and the support plaque (16) must be located in respect to the vertical will e the same as angle (p). In the preferential performance of the present invention said angle is of 45°. As a consequence of the frontal surface of the non metallic cover (13) that covers the sensor plaque (13) and the antenna (12) must have this same angle to induce the user to approach the card with said angle.
Finally in figure 9 another transversal cut is shown on the top part of the electronic proximity lock that houses the proximity detection plaque (3) and the antenna of the communications system (12). In this figure the distance (D1) towards the exterior of the metallic carcass (14)is highlighted in which the group made up by the proximity detection plaque (3) and the antenna (12) and the plaque (16) that supports it in respect to the point which mostly stands out on the lock's metallic carcass (14). We have seen that the bigger the distance, meaning the further out the group is from this external metallic lock carcass (14), the bigger the effective communications distance (D2) is between the communication system integrated in the lock and the card (22). In the present description of the preferential performance it has been seen that parting from a distance (D1) of more than 30 millimetres, the screening effect that is produced by the metallic carcass (14) on the communication field is not worthy.

Claims

Electronic lock operated by the proximity of a key object that contains the adequate means to establish and maintain an information exchange without contact with said lock, the adequate means to store the necessary information for said exchange and the information to be exchanged, in such a manner that said lock is able to determine the subsequent actions of said exchange of information in function of the nature of the exchanged information characterized because it understand:
An electrical proximity detection system, able to detect the proximity of a body or object to a detection plaque, by means of the detection of the variation of capacitance that is generated by this proximity to a detection capacitive element made up by the detection plaque and its surrounding environment. Said detection is produced through counting the number of charge and discharge cycles necessary to generate a first determined voltage between the terminals of a reference capacitive element, understanding said charge and discharge cycles at least one charge pass from the detection plaque connecting it to a second predetermined voltage and another discharge pass to the detection plaque transferring the acquired charge by this plaque to the reference capacitive element, in such a manner that the charge of the capacitive reference element is increased in each charge or discharge cycle, therefore increasing the voltage between the terminals of the capacitive reference element.

An electronic communication system understood as and antenna and an associated circuit able to transmit and receive communications signals, to determine if in this proximity there is a key object or in its case initiate and maintain the exchange of information with it that leads to performing the corresponding actions to the nature of the interchangeable information.

An electronic activation system understood as a circuit that connects the communication system to an electrical supply source, incorporated in the lock or not, in case the proximity detection system has detected the proximity of any body or object to the detection plaque allowing the communication system to activate and detect of the body or object in question is a key object.
Electronic lock operated by proximity in compliance with claim 1, characterized because it understand a microcontroller that commands and integrates the charge and discharge process, counting the number of charge and discharge cycles, and the activation of the communications circuit.
Electronic lock operated by proximity in compliance with claim 1,, characterized because it understands a detection plaque located within an effective antenna communication area, with the plaque having a shape that avoids the appearance of parasite currents in it that way making the communicating signals transmitted by the antenna impermeable, this way achieving that the distortion produced on said communication symbols does not avoid an effective communication with the key object
Electronic lock operated by the proximity of a key object that contains the adequate means to establish and maintain an information exchange without contact with said lock, the adequate means to store the necessary information for said exchange and the information to be exchanged, in such a manner that said lock is able to determine the subsequent actions of said exchange of information in function of the nature of the exchanged information characterized because it understands an automatic activation system by detection of variations of the capacitance in the proximity of the lock which understands:
A detection plaque that together with its environment generates a capacity element whose capacitance varies in function of the environmental conditions and the proximity of a body or object.

An element of capacity reference with a stable capacitance in time or whose variation in function to the environmental conditions is low.

An electronic system that allows at least to discharge both the element of detection of capacity as well as the reference capacity element positioning them in an initial state and that afterwards alternatively allows, disconnect among them the element of capacity of detection and the elements of reference capacity, connect the detection capacity element to an initial voltage source charging said capacity element with a charge in function of its capacitance at that moment, disconnect the detection capacity element from the source of the first predefined voltage, connect between them the changed detection capacity element and the reference capacity element in such a manner that the charge of the detection capacity element passes to the reference capacity element discharge the detection capacity element, generating in this manner a cycle of charge and discharge.

An electronic system that counts the number of charge and discharge cycles necessary so that the reference capacity element reached a total charge that generates a second reference voltage and compares this number of cycles in respect to a number of reference cycles.

An electronic system that once a body or object is detected in the proximity to the detection plaque activates an electronic communication system to recognize if the body or object is a key object or in its case initiate and maintain the exchange of information with it that leads to performing the corresponding actions to the nature of the interchangeable information.
Electronic lock operated by proximity in compliance with claim 4, characterized because it understands a method of adjustment of the number of reference cycles after each complete charge process and posterior charge of the capacity element through the charge and discharge cycles of the detection capacity element until the stored charge in the capacity reference element generates a second reference voltage in such a manner that the new number of reference cycles is in function of the number of cycles obtained in the complete discharge process of the capacity element and posterior charge of it once finished.
Electronic lock operated by proximity in compliance with claim 4, characterized because it understands a method of determining the presence of a body or object in the proximity of the detection plaque in function of a positive sensitivity value predetermined in such a manner that if the difference between the number of reference cycles and the number of cycles just counted is higher to said sensitivity, it proceeds to the consecutive repetition of complete discharge processes and posterior charge of the reference capacity element, through charge and discharge cycles of the detection capacity element until the stored charge in the reference capacity element generates a second reference voltage, until the number of repetitions reaches an initial number of repetitions of predetermined reference or until in a second number of repetitions or predetermined reference said difference does not surpass said positive sensitivity value
Electronic lock operated by proximity in compliance with claim 4, characterized because it understands a method of determining the presence of a body or object in the proximity of the detection plaque in function of a negative sensitivity value predetermined in such a manner that if the difference between the number of reference cycles and the number of cycles just counted is negative and higher to in absolute value to the absolute value of said sensitivity it proceeds to the consecutive repetition of complete discharge processes and posterior charge of the reference capacity element, through charge and discharge cycles of the detection capacity element until the stored charge in the reference capacity element generates a second reference voltage, until the number of repetitions reaches an initial number of repetitions of predetermined reference or until in a second number of predetermined reference repetitions said difference is not negative or its absolute value does not surpass the absolute value of said negative sensitivity value
Electronic lock operated by proximity in compliance with claim 4,, characterized because it understands a detection plaque located within an effective antenna communication area, with the plaque having a shape that avoids the appearance of parasite currents in it that way making the communicating signals transmitted by the antenna impermeable, this way achieving that the distortion produced on said communication symbols does not avoid an effective communication with the key object
Automatic activation and communication unit without contact and of low energy consumption in electrical or electronic stand-alone devices fed by means of batteries operated by proximity of a key object that contains, the adequate means to establish and maintain information exchange without contact with said automatic activation and communication unit, the adequate means to store the necessary data for said exchange and the information to be exchanged, in such a manner that said automatic activation and communication system unit is able to transmit to the device in which the signals are integrated or adequate information so that said device executes the subsequent actions of said exchange of information in function of the nature of the exchanged information characterized because it understands:
An electrical proximity detection system, able to detect the proximity of a body or object to a detection plaque, by means of the detection of the variation of capacitance that is generated by this proximity to a detection capacitive element made up by the detection plaque and its surrounding environment. Said detection is produced through counting the number of charge and discharge cycles necessary to generate a first determined voltage between the terminals of a reference capacitive element, understanding said charge and discharge cycles at least one initial charge pass from the detection plaque connecting it to a second predetermined voltage and a second discharge pass to the detection plaque transferring the acquired charge by this plaque in the initial pass to the reference capacitive element, in such a manner that the charge of the capacitive reference element is increased in each charge or discharge cycle, therefore increasing the voltage between the terminals of the capacitive reference element.

An electronic communication system understood as and antenna and an associated circuit able to transmit and receive communications signals, to determine if in this proximity there is a key object or in its case initiate and maintain the exchange of information with it that leads to performing the corresponding actions to the nature of the interchangeable information.

An electronic activation system understood as a circuit that connects the communication system to an electrical supply source, incorporated in the unit or not, in case the proximity detection system has detected the proximity of any body or object to the detection plaque allowing the communication system to activate and detect of the body or object in question is a key object.
Low energy consumption non contact automatic activation and communications unit in compliance with claim 9, characterized because it understands a detection plaque located within an effective antenna communication area, with the plaque having a shape that avoids the appearance of parasite currents in it that way making the communicating signals transmitted by the antenna impermeable, this way achieving that the distortion produced on said communication symbols does not avoid an effective communication with the key object.