FR2663145A1 - "Hands-free" device for remote identification - Google Patents

Abstract

This device includes a receiver 5 capable of receiving remotely a stimulus from a transmitting and receiving source 4, and a transmitter 6 capable of transmitting back a response such as a code, to the said source; it furthermore includes microprocessor-based recording means 7 for decoding and time base 8 which are wired to the output of the said receiver 5 so as to store messages transmitted by the said source.

Description

"Hands-free" device for remote identification.

 The present invention relates to an identification device.

 An identification device is first of all a means of memorizing digital data which is easy to carry on oneself, low cost and autonomous in energy.

It can be used to read the information it contains (read mode), or for, possibly after reading this information, the recording of other information, additional or replacement (read / write mode).

 Among these devices, we know in particular magnetic identification cards, which do not require an energy source and which have found a privileged application as "authorization titles" or "access control" physical or immaterial to various services.

 Magnetic cards, however, have the disadvantage of having to be taken out of their place of storage on the person of the holder, in order to be able to be physically inserted in a reader. This is a major defect when the user - as is often the case with his function - has his hands occupied, or when the environment is hostile (dusty atmosphere - abrasion of the card) or wet).

 This is why, and to remedy these drawbacks inherent in the very principle of magnetic cards, the invention relates more specifically to an identification badge worn by a person and intended to operate permanently so as to be able to detect reception if necessary. a coded remote control radio signal emitted by a transmitting and receiving source for reading and recording from which said badge can be located at a relatively great distance, in principle being a so-called "hands-free" badge that it should not be necessary to grasp in the hand to approach it from said emitting source.

 Such a badge may therefore comprise on the one hand a radio wave receiver with permanent operation, with extremely low consumption of electric current, suitable for receiving the control signals emitted by said transmitting and receiving source, and on the other hand a transmitter. own, after receipt of an appropriate control signal by said receiver, to send back to said source, a radio signal carrying a message such as an identification code.

 Known devices of this type (called "hands-free") can operate up to distances of the order of 3m, but only work (unlike magnetic cards) in read mode: it is impossible to introduce information other than that which they carry from the outset, which of course limits its value.

 The object of the present invention is to remedy this shortcoming, and for this purpose, a “hands-free” device for remote identification of the general type defined above will, in accordance with the invention, be characterized in that it further comprises recording means connected to the output of said receiver and suitable for storing information transmitted by said source.

 We thus combine the advantages of magnetic cards and those of so-called "hands-free" devices, which can be read from a distance.

 Such a device will also preferably comprise a logic circuit with memory, suitable for being actuated by the output signals of said receiver, this circuit being provided with a time base capable of enabling it to recognize the different chronologies of the changes of state of a modulated signal called "stimulus" emitted by said emitting and receiving source, in order to be able to differentiate these stimuli and thus determine the operating mode requested by said source (simple reading of a signal emitted by said emitter after reception of a stimulus or recording of information in the memory of said logic circuit after reception of another stimulus, distinct from the previous one by the chronology of its changes of state).

Thus, the operation of a device according to the invention may be characterized by a half-wave radio transmission between the transmitting and receiving source for reading and recording (called to simplify, in what follows, the "reader-recorder"), this transmission comprising the following two phases
- the emission of a stimulus, on a determined frequency, by said reader-recorder (in principle located at a fixed station) then the stopping of all emission and
- the possible response of the identification device (badge) by a radio transmission from its transmitter.

 The stimuli will thus have to have several forms, depending on the function requested from the device, these different forms being, as indicated above, constituted respectively by different chronologies of the transitions between two modulation states (state A, state B) of the stimulus, like this will be better seen below.

 Of course, the receiver of the device must be able to detect these stimuli and differentiate their different states, with the sensitivity and autonomy requested. Such a receiver has been described in the French patent application also filed by the applicant on May 29, 1990 under the registration number 90 06638.

 It should be noted that the stimuli referred to above constitute at the same time orders for "awakening" of the logic circuit, which is otherwise inactive. These awakening stimuli are already known in themselves, but until now they carried no other message than the waking order. According to the invention, it can be seen that they carry as an additional message the operating order which is given to the identification device: reading operation, or operation for recording this or that specific message or data.

The invention will in any case be better understood on reading the description which follows of one of its embodiments, made with reference to the figures of the appended drawing in which
- Figure 1 shows the principle of use of a device according to the invention;
- Figure 2 shows the layout of the various components of the device on a support advantageously having the shape and dimensions of a magnetic card
- Figure 3 shows the diagram of the electrical assembly more fully; and
- Figures 4a and following show an example of the shape of the signals used in the device.

 In Figure 1, the identification device (badge) according to the invention has been referenced 1; it is worn by a user 2 whose hands are occupied and who is authorized to access a controlled area, closed by a door with automatic opening 3. This door is itself under the control of a reader-recorder 4, ci above called "source transceiver reading and recording". The badge 1 can advantageously be in the form and the dimensions of a magnetic card. The layout of its various components has been shown in Figure 2.

 In this figure, the receiver has been referenced 5, the transmitter 6, the microprocessor logic circuit 7; the time base for pacing this microprocessor is shown in 8 and the power supply stack in 9. In 10 we have shown diagrammatically a frame consisting of a coil with two windings forming two air antennas superimposed an antenna L2 of emission and a receiving antenna L1, tuned (capacitor C1) on the same modulated frequency (for example 125 kHz). The time base can be provided by any suitable piezoelectric transducer, for example a ceramic. The same components have been referenced in the same way on the more complete diagram of FIG. 3. In this figure, DL is also represented, which is the output signal (demodulated) of receiver 5, "Init" which designates a signal "reset" or wake-up of the logic circuit 7 with microprocessor, and DB which designates the modulation command whose sequence of successive states corresponds for example to the personal code of the user, entered in the memory of logic circuit 7 and entered, at the request of the reader-recorder 4, on the transmitter 6 of the device. The reference f denotes in this figure the frequency of transmission and reception. It is provided for example by a divider by 8 from the frequency of the ceramic (1 MHz in the example chosen).

That said, the general principle of operation of the device will be as follows
The “hands-free” badge 1 is normally in a rest state, its logic circuit 7 is in “stop” mode, and its clock is stopped; its current consumption is minimal, corresponding only to the needs for maintaining the data written in its RAM memory. So that the device can correctly interpret a command sent by the reader-recorder 4, it is therefore necessary to bring it out of its rest state and to reset its functions.

To do this, the reader-recorder 4 periodically emits (for example every 256 ms) a stimulus composed of two consecutive parts in time
- a part called "wake-up order" intended to allow the receiver 5 to generate an initialization signal (reset) of the microprocessor of the logic circuit 7; and
- a so-called "control" part, intervening after the wake-up order and after a time sufficient for the microprocessor to finish its initialization, the wave modulation states of which are scrutinized by the microprocessor in order to then determine execute the corresponding order. This "control" part of the stimulus is emitted by the reader-recorder 4 by imposing, during successive time intervals, modulation states determined so as to constitute bits then sequences of bits constituting in turn the words which form the command.

 Thus, the microprocessor will execute the order which is transmitted to it: transmission by the transmitter 6 of one of the codes attached to the badge (causing for example the opening of door 3), or storage in the memory (RAM) of the circuit logic 7 of the badge of one or more words issued by the reader-recorder 4.

 The following figures show an example of such signals modulated (FIG. 4a) and rectified and demodulated DL at the output of the receiver 5 (FIG. 4b), an initialization signal being represented in FIG. 4c.

In a preferred embodiment, it can be seen in FIG. 4a that A denotes the absence of the modulated wave, and
B the presence of this wave, the BAB sequences ... in their different combinations constituting the word to be transmitted after termination of the wake-up wave R.

 The wake-up order is coded by a modulation state B over a time interval of duration greater than or equal to, for example, 8 ms, followed by a state A of equal duration.

 In a control word, a bit can be determined by three successive time intervals lasting for example each 1333 ps. For example, a bit of value 0 can be supplied by the sequence BAA, and a bit of value 1 by the sequence BBA. In this case, a bit therefore lasts 1333 ms x 3 = 4 ms. The transmission speed between the reader-recorder and the badge is therefore in this example 250 bits / s.

 In general, any modulation state B sent to the “hands-free” badge 1 for a period greater than one bit causes a reset of the badge, regardless of the state in which it is located. The reader-recorder 4 transmits its messages to the identification device by 4-bit words plus a parity bit, transmitted in series, each word being separated from the previous one by sufficient time for its interpretation by the hands-free badge. This slight separation of the words in time means that the duration of the modulation states A in the transmission is not significant.

 As for the transmission between the identification device 1 (or "hands-free" badge) and the reader-recorder 4, it can be done by following the same general coding principles, and by using two modulation states: A '( absence of the wave) and B '(presence of the wave). A bit of value 0 can thus be determined by the sequence B'A'A ', and a bit of value 1 by the sequence B'B'A'. The duration of each time interval is 666 rs, so that the transmission speed in this direction is 500 bits / s. The messages are transmitted by the badge in 8-bit words without parity, transmitted in series, each word being of course separated from the previous in time, the duration of the modulation states A ′ in the transmission not being significant again.

Claims (2)

 1. "Hands-free" device for remote identification, which can be established in particular in the form of an identification badge (1) worn by a person and intended to operate permanently so as to be able to detect reception if necessary. of a coded remote control radio signal emitted by a transmitting and receiving source for reading and recording (4) from which said badge can be located at a relatively great distance, in principle being a so-called "hands-free" badge "which it should not be necessary to grasp in the hand in order to approach it from said transmitting source, this badge (1) comprising for this purpose, on the one hand, a radio wave receiver (5) with permanent operation, with an extremely low consumption of electric current, suitable for receiving and demodulating the control signals transmitted by said transmitting and receiving source (4), and on the other hand a clean transmitter (6), after reception of a control signal appropriate by said receiver to transmit back to said source (4), a radio signal carrying a message such as an identification code, device characterized in that it further comprises recording means (7) connected to the output of said receiver (5) and adapted to store information emitted by said source (4).  2. Device according to claim 1, characterized in that it comprises a memory logic circuit (7), suitable for being actuated by the output signals of said receiver (5), this circuit being provided with a suitable time base to allow it to recognize the different chronologies of the changes in state of a modulated signal called "stimulus" emitted by said emitting and receiving source (4), in order to be able to differentiate these stimuli and thus determine the operating mode requested by said source (simple reading of a signal emitted by said emitter (6) after reception of a stimulus or recording of information in the memory of said logic circuit after reception of another stimulus, distinct from the previous one by the chronology of its changes d 'state).