Security system

A security system of the type having a fixed terminal and a portable unit such as a remote control. The portable unit produces an activation signal based on active intervention by a user and a measurement signal based on the measurement of a biometrical signature of the user. A control signal is generated when the activation and measurement signals are both generated within a specified temporal window and the measured biometrical signature corresponds to that of an authorized user. Thus, there is a reduced chance of both the security system being disarmed by an ill-intentioned third party and of untimely or inadvertently disarming the system.

CROSS-REFERENCE TO RELATED APPLICATIONS 
This application is based upon and claims priority from prior French Patent 
Application No. 97-16467, filed Dec. 24, 1997, the entire disclosure of 
which is herein incorporated by reference. 
BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to security systems, and more specifically to 
security systems of the type having a fixed terminal and a portable unit 
that delivers a signal to the fixed terminal. 
2. Description of Related Art 
A conventional automobile security system is one example of a security 
system that has a fixed terminal and a portable unit that delivers a 
lock/unlock signal to the fixed terminal. In the typical automobile 
security system, the fixed terminal is a device for the centralized 
locking and unlocking of the vehicle and the portable unit is a remote 
control for operating the locking and unlocking device. The portable unit 
is designed to be carried by an authorized user (e.g., the vehicle owner), 
and under certain conditions delivers the lock/unlock signal to the fixed 
terminal in order to remotely lock or unlock the doors of the vehicle. 
(This description uses the term "fixed", for example in designating the 
locking and unlocking device on the vehicle, in a relative sense and the 
term should be understood with reference to the portable unit.) 
The lock/unlock signal from the portable unit is generally transmitted by a 
carrier wave such as an electromagnetic or infrared wave, and typically 
includes a fixed or changing code (i.e., a code whose value depends on the 
number of previous transmissions). The code must be recognized as valid by 
the fixed terminal in order for the signal to prompt the locking or 
unlocking of the doors of the vehicle. While this provides some anti-theft 
protection, the security level of such a system against theft is still 
imperfect because the mere physical possession of the portable unit is 
generally sufficient to effect the unlocking of the vehicle. Thus, if the 
portable unit is lost or stolen, an ill-intentioned third party can easily 
use the portable unit to open the doors of the vehicle and then remove 
articles inside the vehicle or even steal the vehicle. 
To overcome this problem, a security system can be associated with its 
authorized user (or users) so that only an authorized user can unlock the 
doors of the vehicle. For example, the system can include means for 
measuring a biometrical signature of an authorized user. With such a 
means, the security system can use a biometrical signature such as a 
fingerprint, the iris of the eye, or an audiometrical spectrum of the 
authorized user's voice to identify or authenticate a physical person. To 
this end, it has been proposed to use a voice recognition module in the 
fixed terminal of a security system to control the locking or unlocking of 
the vehicle upon the sound of the authorized user's voice. In such a 
system, the portable unit becomes superfluous and can be eliminated to 
produce a "hands-free" access system. 
While such a system would provide some advantages over conventional 
security systems, there is a risk that the vehicle will be accidentally 
unlocked. For example, when in the vicinity of the vehicle, the authorized 
user could inadvertently pronounce a word or sequence of words that 
prompts the unlocking of the vehicle. If the user does not realize that 
this has happened, the user may walk away and thus inadvertently leave the 
vehicle unguarded with its doors unlocked. 
SUMMARY OF THE INVENTION 
In view of these drawbacks, it is an object of the present invention to 
remove the above-mentioned drawbacks and to provide a security system of 
the type associated with an authorized user (or users) that has a reduced 
chance of an inadvertent or untimely unlocking of the vehicle. The 
security system includes a fixed terminal and a portable unit that 
provides the fixed terminal with a signal for locking and unlocking a 
functional unit (e.g., a vehicle). The portable unit includes a detector, 
a measurement device, and a signal generator. The detector generates an 
activation signal when active intervention by a user is detected, and the 
measurement device measures a biometrical signature of the user. When the 
activation signal and a measurement signal are produced within a specified 
temporal window, the signal generator generates the lock/unlock signal if 
the measured biometrical signature corresponds to that of an authorized 
user. Because the measurement of a valid biometrical signal is necessary 
to prompt the portable unit to transmit the lock/unlock signal, an 
ill-intentioned third party possessing the portable unit cannot use it to 
unlock the vehicle. Further, because an active intervention by the user is 
still necessary to transmit the lock/unlock signal, the chance of untimely 
or inadvertently unlocking the vehicle is significantly reduced or 
eliminated. The present invention also preserves the function of a remote 
unit so that the users' current habits do not have to be significantly 
modified. 
Other objects, features, and advantages of the present invention will 
become apparent from the following detailed description. It should be 
understood, however, that the detailed description and specific examples, 
while indicating preferred embodiments of the present invention, are given 
by way of illustration only and various modifications may naturally be 
performed without deviating from the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
Preferred embodiments of the present invention will be described in detail 
hereinbelow with reference to the attached drawings. 
FIG. 1 is a simplified illustration of a security system for an exemplary 
functional unit in the form of an automobile. The automobile 101 is fitted 
with an onboard fixed terminal such as a centralized locking and unlocking 
unit 102. The security system also includes a portable unit 103 such as a 
"remote" control that is usually associated with a key for the vehicle. 
(In the following description, the portable unit is identified with the 
remote control or the key for the vehicle and these three expressions are 
used without distinction.) 
The portable unit is designed to be carried and operated by an authorized 
user 104 (e.g., the owner of the vehicle), and other authorized users can 
use the same portable unit 103 or another unit of the same kind that is 
assigned to them for the same function. Under certain conditions, the 
portable unit 103 delivers a lock/unlock signal SD to the fixed terminal 
102 by means of a carrier wave such as an electromagnetic or infrared 
wave. In preferred embodiments, the lock/unlock signal SD is an 
amplitude-modulated or phase-modulated radio frequency signal that is 
generated by the portable unit. 
FIG. 2 shows a more detailed view of a portable unit in the form of a key 
in accordance with an embodiment of the present invention. The key 103 has 
a conventional metal portion 12 that forms a key insert and an upper 
portion 11 that forms the head or grasping portion of the key. The upper 
portion 11 fulfills a remote control function of the system. For this 
purpose, the upper or remote control portion in the illustrated embodiment 
is a plastic portion containing an electronic circuit that transmits the 
lock/unlock signal SD. The remote control portion includes detection means 
for detecting the active intervention of the user in a known manner. For 
example, the detection means can include one or more keys of a keyboard, 
or more simply a switch SW (e.g., a push-button type switch) that is 
positioned under a first region 13 of the remote control portion 11. The 
first region 13 of the remote control portion can be folded by pressure 
exerted by the user's thumb 15 (e.g., because of a smaller thickness or 
the presence of adjacent ribs) to activate the switch SW within the remote 
control portion 11. 
Additionally, the remote control portion 11 includes measurement means for 
measuring a biometrical signature of the authorized user of the vehicle. 
In one embodiment, the measurement means includes a microphone and a 
voice-recognition device that identify the user's voice. However, in 
preferred embodiments such as the one shown in FIG. 2, the measurement 
means includes a fingerprint sensor CED that is located within the remote 
control portion 11 of the portable unit 103. The active surface of the 
sensor CED is flush with an outer surface of the plastic portion 11 of the 
key. 
Sensors suitable for such use are currently available in the form of 
monolithic integrated circuits at prices that are compatible with the 
market for automobile security systems. Further, these sensors are 
sufficiently precise, reliable, and compact for such an application. For 
example, one such sensor is manufactured by STMicroelectronics S.A. 
(Gentilly, France) under the reference STFP2015-50. This particular sensor 
has an active surface area of less than 2 cm.sup.2 that includes nearly 
100,000 detection cells arranged in a matrix. The entire active surface 
area is scanned eight times per second and serial digital data 
corresponding to the active surface scanning is delivered. 
In the illustrated embodiment of the present invention, the fingerprint 
sensor CED is positioned beneath a second region 14 of the remote control 
portion 11 that is opposite the first region 13. This allows the user's 
index finger 16 to contact the second region 14 containing the sensor 
while the thumb 15 contacts the first region 13 containing the switch when 
the plastic portion 11 of the key is clamped between these fingers. In 
some alternative embodiments, the sensor is positioned on the surface of 
the plastic portion 11 at the level of the first region 13 so that the 
user's thumb 15 is applied against the active surface of the sensor while 
also exerting pressure through the sensor to activate the push-button SW. 
While two mechanical layouts for the switch and sensor in the portable 
unit have been described, the present invention is not limited to only 
these specific structures. The elements of the portable unit can be laid 
out in any appropriate manner in accordance with design preferences by one 
of ordinary skill in the art, and thus specific structures are not 
described in detail. 
FIG. 3 is a block diagram of a portable unit according to one embodiment of 
the present invention. As shown, the portable unit includes detection 
means for detecting active intervention by a user and producing an 
activation signal SA1. In one embodiment, the detection means is formed by 
a switch SW that has a first terminal connected to the positive terminal 
of a voltage source ST1, and a negative supply terminal of the voltage 
source is connected to ground. The activation signal SA1 is delivered by 
the second terminal of the switch SW. Thus, the activation signal SA1 is 
active (e.g., in the "1" state) when the switch SW is closed. 
However, in the illustrated embodiment, the detection means includes the 
switch SW and a timer MS1. The first terminal of the switch SW is 
similarly connected to the voltage source ST1, but the timer MS1 is 
connected to the second terminal of the switch and outputs the activation 
signal SA1. In this embodiment, the timer is a monostable circuit with a 
time constant T. The timer has the effect of holding the activation signal 
SA1 in the active state for a specified time, which corresponds to the 
time constant T, after the closing of the switch SW. Thus, even if the 
pressure exerted on the switch by the user's thumb is stealthy, the 
activation signal is kept active for the specified time. This is 
especially advantageous when the switch is of a stealthy type such as a 
push-button. 
Additionally, the portable unit includes measurement means CED, preferably 
in the form of a fingerprint sensor, for measuring a biometrical signature 
of the user and delivering a measurement signal SM2. The portable unit 
also includes generation means for generating the unlock signal SD when 
the activation signal SA1 and the measurement signal SM2 are produced 
within a specified temporal window and the measured biometrical signature 
corresponds to an authorized user. The generation means is in the form of 
a control circuit 20 having a first input E1 that receives the activation 
signal SA1 and a second input E2 that receives the measurement signal SM2 
from the sensor CED. 
The control circuit 20 also includes a microcontroller M1 that has a memory 
DB2 in which biometrical signatures of one or more authorized users are 
stored (e.g., the fingerprint of the thumb, index finger, or any other 
finger). Preferably, each biometrical signature is stored as a matrix of 
binary data and the biometrical signatures of each authorized user are 
stored in distinct areas of the memory DB2 that are referenced by a user 
number. For example, five distinct areas could be reserved for storing the 
biometrical signatures of five different authorized users (e.g., the 
members of a family), with each user being fictitiously associated with a 
user number (e.g., 1, 2, 3, 4 or 5). It is also preferable to have the 
fingerprint sensor CED deliver the measurement signal SM2 as a digital 
signal so that the data supplied to the second input E2 of the control 
unit 20 can be directly exploited by the microcontroller M1. Otherwise, it 
is necessary to provide an analog-to-digital converter for the measurement 
signal. 
The microcontroller M1 is driven by a control program. When the data 
elements of the measurement signal SM2 correspond to the data elements 
stored in one of the areas of the memory DB2, the microcontroller M1 
delivers an output signal OUT. The output signal OUT is then supplied to a 
transmission circuit ER2 to prompt the transmission of the unlock signal 
SD, for example through an antenna, infrared diode, or electrical 
connection. In order to provide a clear illustration of the logical 
combination of the activation signal SA1 and the measurement signal SM2 
within the control unit 20, FIG. 3 shows an AND gate PL2 that receives the 
activation signal SA1 at one input and the measurement signal SM2 at 
another input. The output of the AND gate PL2 is supplied to an input i1 
of the microcontroller M1. 
The AND gate PL2 is shown solely to illustrate one of the conditions that 
governs the transmission of the unlock signal (i.e., that the activation 
signal SA1 and the measurement signal SM2 are generated within a specified 
temporal window). With such a configuration, the measurement signal SM2 
from the sensor CED only reaches the microcontroller M1 when the 
activation signal SA1 is active. However, this representation is not meant 
to imply any limitations on practical embodiments of the present 
invention. For example, the two signals SA1 and SM2 could be transmitted 
to two distinct inputs of the microcontroller M1 in order to be processed 
by the microcontroller in an AND-type logic operation. 
Further, it will be noted that the temporal window during which the 
activation signal SA1 is kept active must at least be equal to the 
duration of the transmission through the measurement signal SM2 of the 
data elements corresponding to a user's fingerprint. It is presently 
believed that a temporal window of 500 milliseconds is sufficient for this 
purpose. Additionally, because both the activation signal and the 
measurement signal must be generated within the specified temporal window 
in order to generate the lock/unlock signal, problems of order and/or 
synchronization between the occurrence of these two signals are avoided. 
In some embodiments of the present invention, the portable unit also 
includes other measurement means for measuring biometrical data elements 
corresponding to the user and generating other measurement signals. Then, 
the generation means generates the unlock signal SD when the activation 
signal SA1 and all of the measurement signals SM are produced within the 
specified temporal window and the measured biometrical signatures 
correspond to those of an authorized user. For example, a second 
biometrical data element of the user could be the arterial blood pressure 
measured at the finger, and a third biometrical data element of the user 
could be the temperature of the finger. 
In the illustrated embodiment, a pressure sensor CPR and a temperature 
sensor CTP are also provided to measure these biometrical data elements of 
the user. By taking such additional biometrical data elements of the user 
into account, it becomes more difficult to fraudulently unlock the 
vehicle. For example, the illustrated embodiment can thwart an attempt to 
fraudulently unlock the vehicle by manufacturing an artificial finger 
(e.g., of latex) that has a faithful reproduction of an authorized user's 
fingerprint. As shown in FIG. 3, a second AND gate PL3 receives a second 
measurement signal SM3 from the pressure sensor CPR at one input and the 
activation signal SA1 at another input. Similarly, a third AND gate PL4 
receives a third measurement signal SM4 from the temperature sensor CTP at 
one input and the activation signal SA1 at another input. The outputs of 
the second and third AND gates PL3 and PL4 are supplied to second and 
third inputs i2 and i3 of the microcontroller M1. 
In one embodiment of the present invention, the unlock signal SD includes 
an impersonal code to identify the authorized user whose biometrical 
signature has been measured and recognized to be valid. The impersonal 
code can simply be the corresponding user number (e.g., 1, 2, 3, 4, or 5 
as described above). By transmitting the impersonal code, selected 
convenience functions in the vehicle can be activated when the unblock 
signal SD is received. For example, such functions could include the 
adjusting of the positions of the seats and the positions of the rearview 
mirrors, the setting of a selected temperature of the onboard thermostat, 
the tuning of the radio to a particular station, and so on according to 
predefined values corresponding to the preferences of one of the users. 
In such embodiments, the portable unit transmits an impersonal number such 
as 1, 2, 3, 4, or 5 that merely identifies one of the authorized users 
from among the set of authorized users, and not information relating to 
the user's biometrical signature (hence the expression "impersonal code"). 
Thus, the data elements pertaining to the authorized user's biometrical 
signature cannot fall into the hands of an ill-intentioned third party 
that intercepts the unlock signal SD. Preferably, the unlock signal SD 
also includes a code for identifying the vehicle associated with the 
portable unit so that a specified portable unit can be associated with a 
single vehicle. 
The exact structure, features, and operation of the fixed terminal (e.g., a 
centralized door locking and unlocking unit) are not critical to the 
present invention and can conform to conventional fixed systems. At the 
least, the selection and design of the fixed terminal are within the scope 
of one of ordinary skill in the art so the fixed terminal will not be 
described in greater detail. Furthermore, the lock/unlock signal can also 
include a standard type of open-ended code (i.e., a code whose value 
changes with each transmission). Such a code can be used to hinder 
fraudulent attempts at picking up and recording (with appropriate 
electronics) the lock/unlock signal when it is normally transmitted by an 
authorized user and then subsequently and fraudulently reproducing the 
signal to unlock the vehicle. 
While there has been illustrated and described what are presently 
considered to be the preferred embodiments of the present invention, it 
will be understood by those skilled in the art that various other 
modifications may be made, and equivalents may be substituted, without 
departing from the true scope of the invention. Additionally, many 
modifications may be made to adapt a particular situation to the teachings 
of the present invention without departing from the central inventive 
concept described herein. Furthermore, embodiments of the present 
invention may not include all of the features described above. Therefore, 
it is intended that the present invention not be limited to the particular 
embodiments disclosed, but that the invention include all embodiments 
falling within the scope of the appended claims.