Surface texture reading access checking system

Surface texture reading access checking system. The identification information attached to each support object serving as a key is constituted by the texture of a surface portion of said object. A reader reads this information and communicates it to the processing means, which carry out a comparison between the signal read and recorded signals. Application to the production of locks or access checking means for data processing, telematic, banking and similar systems.

BACKGROUND OF THE INVENTION 
The present invention relates to an access checking system, i.e. a system 
making it possible to initiate an action equivalent to an authorisation 
following the checking of the identity of an object introduced into said 
system. 
To a certain extent the system according to the invention constitutes a 
"key-lock" system, provided that these terms are given a broad sense. The 
word "key" must be understood to designate a support object provided with 
an identity and the word "lock" is understood to mean a member able to 
recognise the identity in question and control an action. However, the 
support object according to the invention is not necessarily in the 
traditional form of a key. It can have a random shape and can in 
particular be a card. With respect to the "control member" function, it is 
not necessarily limited to the action on the latch or bolt of a door, but 
can correspond to an access authorisation to a random data processing, 
telematic, bank or similar system. However, in order to show the 
originality and essential features of the invention, the variant of the 
system assuming the form of the traditional "key-lock" system will be used 
as a basis, but without this example having any limitative character. 
The very principle of the lock mechanism is to give a portable object (the 
key) an identity (e.g. a profile) and to provide a member (the lock) able 
to recognise this identity and initiate an action. According to this known 
principle, the key is a reproducible object, because obviously several 
people must be able to have the same key (the members of one family, the 
same company, etc.). As the lock is linked with the special form given to 
the key, it can only cooperate with a single type of key. 
Recently more sophisticated systems have appeared and these can be 
designated by the generic term of "electronic locks". In such systems, the 
identity is translated into a code written on an optical or magnetic 
track, which is placed on a type of credit card. However, the philosophy 
of the system remains the same, each key (in the present case each card) 
being reproducible. However, as in such improved systems the identity 
information is of a numerical and no longer a mechanical nature, it is 
possible to record several different identities in an electronic memory. 
Several different keys are then able to open the same lock. These keys can 
be allocated to different authorised persons, but can also be used by 
maintenance or security services. 
In such systems, several digital words are written into a random access 
memory, which to a certain extent acts as a reference and these same words 
are written on to several cards. When one of these cards is introduced 
into a card reader, the code written on the card is detected and the 
resulting digital signal is compared with various reference words written 
in the memory. A comparitor establishes whether or not coincidence exists 
between the read word and one of the stored words. In the affirmative, a 
signal is emitted for controlling a random action, e.g. the opening of a 
catch. 
For example, such a system is described in French patents Nos. 2 107 529, 2 
325 992, 2 457 524 and 2 533 340. 
Although satisfactory in certain respects, these systems suffer from a 
major disadvantage linked with the absence of confidentiality of the code 
carried by the card. Thus, it is easy to read the code inscribed on a 
stolen card and to re-write said code on a new card. In other words there 
is a real risk of fraudulent duplication of the support. 
The object of the invention is to obviate this disadvantage. This is 
achieved through the use of a key which, by its very nature, is not 
reproducible. This characteristic is obtained by choosing as the 
information able to define the identity of a key a natural information 
constituted by the texture of the surface of a member and not information 
artificially produced (such as a tooth system or a magnetic or optical 
property of a strip). This information is of a complexity such that it is 
not reproducible. In addition, said information is unique, because even 
two objects which are identical in the macroscopic sense are in reality 
different on descending to the level of their surface texture. There is 
obviously no reason why an artificial texture should not be added to the 
natural texture in the form of scratches, streaks, marks, etc. 
The idea of using the texture of a surface as the identification means for 
certain objects is not new. The article by B. C. D'Agraives et al entitled 
"Surface Topography, a remarkable method for the identification of seals 
or structures in general", published in "Proceedings of the 3rd Esarda 
Symposium on Safeguards and Nuclear Material Management", Karlsruhe, 
Federal Republic of Germany, 6/8.5.1981, already describes the properties 
and interest of surface textures. This teaching also appears in British 
patent application No. 2 097 979 published on 10.11.1982 in the name of 
the European Atomic Energy Community (EURATOM) and entitled "Utilisation 
of surface textures as a random marking or unique identity". 
The present invention takes up this idea again by applying it to the field 
of access checking systems. 
The choice of the surface texture as an information source for the marking 
of key runs counted to all the aforementioned known principles because, by 
its very nature, said information is not reproducible. Thus, unlike in the 
past, the lock is no longer designed to recognise a predetermined 
information, because a texture is a virtually random magnitude and is 
consequently unforeseeable. Thus, it is no longer possible to load the 
memory of the lock with an information which has been determined 
beforehand, as was the case with the Prior Art systems. It is pointed out 
in this connection that in conventional electronic locks and as described 
in particular in French patent No. 2 325 992, loading takes place with the 
aid of a special card, which carries programming information relative to 
the lock. This information consists of lists of codes to be accepted and 
lists of codes to be refused. This programming card is introduced into the 
reader, which identifies it as such and which is designed so as to modify 
the list of stored codes. 
This known system is still subject to a fraud risk, because it is possible 
to falsify the programming card by giving it forged codes. Thus, the lock 
can be controlled by cards carrying these forged codes. 
The choice of the surface texture as the identification means makes it 
necessary to modify the authorised information loading procedure, so that 
it is impossible to forge or counterfeit the same. To this end, the lock 
according to the invention which, like electronic locks, is provided with 
different memory locations is such that these locations can only receive 
the reference information by reading keys which are authorised to open the 
lock. In other words, an information written on a support is no longer 
written into the lock memory. The reverse order is used according to the 
invention, i.e. keys are produced with a random texture and the locks are 
subsequently conditioned as a function of said keys. 
According to the invention, the quantity used for identifying the key is a 
continuous analog quantity and is no longer a digital value. Thus, an 
analog procedure could optionally be adopted for the comparison operation 
between the reference quantity and the read quantity. However, it is 
natural that preference is given to the conversion of the analog signal 
into digital form, followed by digital processing. 
Another original feature of the lock according to the invention is that the 
means responsible for reading the information contained in the support 
supplied thereto is a texture reader and no longer a magnetic reader. 
It is pointed out that the advantages of the system according to the 
invention are not acquired to the detriment of the possibilities of 
conventional electronic systems which are entirely retained, i.e. 
temporary validation of a key, centralised management of a system of 
locks, counting the number of interventions of a particular key, etc. 
SUMMARY OF THE INVENTION 
In general terms, the present invention can be defined as follows. It 
relates to an access control system making it possible to initiate an 
action after checking the identity of a support object introduced into 
said system and carrying an identification information, said system 
comprising in per se known manner a reader able to receive such a support 
object and read the information belonging to the same, a storage means 
having several memory locations loaded by reference informations 
corresponding to an authorised support object system, a comparison means 
between on the one hand a signal supplied by the reader when a random 
support object is introduced into the station and on the other hand each 
of the informations stored in the memory locations, said comparison means 
determining the degree of coincidence between the information 
corresponding to the support object introduced into the reader and one of 
the informations contained in the memory locations of the storage means 
and a circuit connected to the comparison circuit and supplying, when the 
degree of coincidence is adequate, a signal constituting a signal for 
initiating an action, wherein the identification information attached to 
each support object is constituted by the texture of a surface portion of 
said support object, the reader then being a surface texture reader, the 
loading of a reference information taking place by introducing an 
authorised support object into the reader, reading said support object and 
storing the signal read in one of the locations in question. 
According to a first embodiment, each support object is in the form of a 
key with a head which can be manually grasped and a body having at least 
one planar portion carrying the surface portion whose texture is read. 
According to an advantageous variant, the key body is metallic and 
preferably made from an alloy, which gives a particular complexity to the 
texture. 
According to another embodiment, each support object is in the form of a 
card, whereof part of the surface is used for reading the texture. This 
card can be made from a flexible plastic. 
According to yet another embodiment, the key can have a cylindrical shape 
with reading which is either rotary along the circumference or linear 
along a generatrix. The key can have a tubular appearance, reading taking 
place inside or outside the tube. 
According to yet another embodiment, the key can consist of a conventional 
object such as a ballpen. 
The reader comprises a support object reception block, a transducer able to 
translate the key relief into an electrical signal (e.g. a piezoelectric 
point), said transducer being placed on an arm and a means for the 
relative displacement of the arm and the support object along a surface 
portion thereof. According to an advantageous embodiment, the arm is 
connected to a displacement means, which is moved when the support is 
immobilised in the reception block. This arm displacement means can be a 
clockwork connected to an arming arm, whereof one end is displaced by the 
introduction of the support object into the reception block. However, said 
arm displacement means can also be an electric motor. 
According to another embodiment, the reading point is stationary and 
support object reading takes place during the introduction thereof into 
the reception block. However, in another embodiment, reading can take 
place during the withdrawal of the key from the reception block. 
The comparison circuit preferably comprises a correlator followed by a 
threshold circuit. It is particularly useful to use a correlator here, 
because the measuring signal is of an analog nature and it is sampled at a 
large number of points, e.g. 512, 1024 or more points. The comparison 
between the read signal and the reference signal can give rise to the 
correlation method, whereas in the Prior Art of electronic locks, there is 
a bit by bit comparison of words of several bytes. Other more or less 
complex processing methods can also be used.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The following description and particularly that relative to FIGS. 1-3 
relates to the special case of a support object in the form of a metal bar 
read by a piezoelectric point placed at the end of an arm moved by a 
clockwork mechanism. However, as stated hereinbefore, other constructions 
are also possible. 
In general terms, the reader can use all known texture sensors covered by 
standards, particuarly French standard NF-E-05-050 of December 1970 
entitled "Surface state of products-general details of electronic sensor 
equipment". 
The device shown in FIGS. 1, 2 and 3 comprises a reception block 10 for a 
key 12 having a trapezoidal section, an abutment 14, a first arm 16 
displaced by the end of the key and mobile about a shaft 18, said arm 
being articulated on a second arm 20, which cooperates with a toothed 
wheel 22 arming a spiral spring 24. When key 12 abuts against abutment 14 
(cf FIG. 2), arm 16 is in position 16', arm 18 in position 18' and wheel 
22 is released. Spring 22 then controls the displacement of a third arm 25 
articulated on to a fourth arm 26, pivoting about an access 28 and whose 
end carries a sensor 30, provided with a reading point 32. The raising of 
the system corresponds to the angular displacement 31 in FIG. 2 and the 
reading phase to the displacement 33. The latter corresponds to a reading 
range 34 located on the upper face of the key and in the form of a 
circular arc. However, it is also possible to provide a system in which 
the reading range is linear. Sensor 30 supplied an analog electric signal 
applied to an electronic circuit 40. The latter comprises all or part of 
the processing means illustrated in FIGS. 4-6. 
FIG. 4 firstly shows the general diagram of an installation realising the 
present invention. It is possible to see a reading block 50 connected to a 
microprocessor 52 by a connecting bus 54. Block 50 is connected to an 
autorelay 56, which is connected to a relay 58 constituted by the control 
relay of member 60, which is either an electric catch or a bolt. The 
assembly is connected to a general power supply 62. Block 50 can also be 
connected to an alarm circuit 64 and to an interface 66 permitting the 
possible connection with another lock of the same type. 
The essential features of the processing means are brought together on an 
electronic card, although in certain applications it would be possible to 
centralise all the processing operations relating to a group of locks in a 
microcomputer designed for this purpose. Such a card is shown functionally 
in FIG. 5. It comprises a microprocessor 70 (e.g. of type 6800 or 6809), a 
clock 72, a random access memory 74 having several memory locations, an 
address decoder 75 and an analog-digital converter 76 connected to reader 
sensor 30. The data flow on a bus 80, the addresses on a bus 82 and the 
control instructions (read-write into memory and sampling-conversion) on a 
bus 84. Microprocessor 70 is connected to an input-output circuit 90, 
which is connected by a connection 91 to the electric catch to be 
controlled (across relays, cf FIG. 4), by connection 92 to a switch and by 
connection 93 to other locks or miscellaneous members. 
The system functions as follows. The analog signal supplied by sensor 30 is 
sampled and each sample is converted into digital form by converter 76. 
Microprocessor 70 receives all the read digital signals and has access to 
the various reference signals stored in 74. With the aid of these two 
data, it carries out a correlation and compares the result obtained with a 
predetermined degree of correlation. 
Microprocessor 70 also ensures the initiation of a signal in the case of an 
attempted forced entry into the box or monitoring members with erasure of 
all the memories, which prevents the data processing and electrical 
opening control; management of the schedule, priorities and lockouts; 
presence checking. These functions can be fulfilled either by wired 
electronic circuits, or by a data processing program. 
Naturally, this diagram can give rise to different embodiments as a 
function of the applications. It is possible to provide a version with an 
autonomous power supply and the bringing of the microprocessor into the 
inoperative state. Part of the random access memory can also be placed in 
an attached box located outside the lock, whilst a supplementary 
microprocessor acting as a central management means can also be provided 
when there are numerous keys or readers. The memory contained in each 
rader then acts as a buffer waiting for the central unit to be available. 
According to measurements carried out by the inventors, the total opening 
time of a lock folliwng the introduction of a key is less than 3 s. for 10 
keys and less than 9 s. for more than 10 keys. 
The card described hereinbefore can communicate with any data processing 
periphery, such as a printer, keyboard, video screen, bulk store, etc. 
The simplified flowchart for a basic program for the putting into action of 
these processing means is illustrated in FIG. 6, where different 
operations of the program are given the following meanings: 
100: Program start. 
101: Program introduction and loading memories. 
102: Monitoring circuit and clock checking. 
103: Alarm. 
104: Key introduction. 
105: Interruption request. 
106: Key reading. 
107: Recording and comparison. 
108: Result processing. 
109: Opening decision. 
110: Alarm. 
111: Monitoring circuit return.