Detection plate for electronic identification system

<td>POLAND REPUBLIC</td><td>PATENT DESCRIPTION</td><td colspan="2"> 128 786</td>

<td>CHINA</td><td></td><td></td><td>READING ROOM</td>

<td></td><td>Additional patent to patent no</td><td></td><td>U Pakowy F · Iwtfr.nt</td>

<td> in</td><td>Reported: 78 04 28 (P. 206454)</td><td colspan="2">Int. Cl. ' G07C 9/00 / ζητη iiMtn</td>

<td>OFFICE PATENT '</td><td>Priority: The application was announced: 80 02 11</td><td></td><td></td>

<td>PRL</td><td>Patent description published: 1986 02 10</td><td></td><td></td>

Inventor of the invention: - Patent holder: NV Nederlandsche Apparatenfabriek NEDAP, Groenlo (Netherlands)

Detection board for electronic identification system and

The subject of the invention is a detection plate for an electronic system for identifying persons, animals and goods that pass a controlled zone.

Identification systems are known which, for example, are used in a building room accessible only to authorized persons or in a large warehouse for automatic registration of goods delivered and received from this warehouse. In such cases, the data of the person, animals or goods are provided with a detection plate containing an electric circuit which, thanks to the electromagnetic field generated in the controlled zone, sends a specific signal or causes a change in the intensity of the electromagnetic field, which can be detected by means of appropriate elements.

In the case of using a signal that is sent again after detection in the detection plate, it is necessary to use, in addition to transmitting systems, receiving systems to receive and process signals. However, in the case when the detection plate affects the generated electromagnetic field, then it is necessary to use only transmitting systems and associated elements to detect (depending on the properties of the detection plate) the change in the electric load of the transmitter, which elements produce specific signals.

The electric circuit contained in the detection plate ensures the creation of a coded signal whose code depends on the type of detection plate, i.e. the person wearing it, the animal or the goods associated with it. This identification system can also be used to identify different people individually. .

Known identification systems can be used, for example, in a barn with a number of troughs available to all cows of the herd concerned. Rational breeding requires the right amount of compound feed to be supplied in measured quantities. To this end, a local electromagnetic field zone is created at each trough, with each cow equipped with a detection plate. In this way, it is possible to identify each cow standing in front of the trough and give it the right compound feed in a measured quantity.

A detection plate for the identification system is known, which is described in U.S. Patent No. 3,299,424, which includes a resonant circuit that is periodically tuned by means of an switching element with a specific coding frequency depending on the auxiliary circuit also included in the detection plate. In order to generate the coding signal and activate the switching member, this board is equipped with its own power supply in the form of a battery, which is its main disadvantage. After a while, the batteries need replacing, and at a time when their voltage

128 796

128 decreases, incorrect coding signals and false identification are generated.

The known detection plate for the electronic identification system is equipped with a receiving stage, a counting system controlled by the receiving stage, an associated coding system for producing plate-specific pulse trains, as well as a DC power supply system.

In the detection board according to the invention, the output of the coding system is connected via a feedback stage back to the resonant circuit formed as the receiving stage. The coding system is connected to the clock output of the digital meter signal for tuning the resonant circuit for given time periods. Preferably, a rectifier circuit comprising diodes is connected to the resonant circuit.

The feedback control includes a switching element controlled by the output of the coding system, in particular a keyed transistor. The degree of feedback may include a non-linear element, preferably a diode, which is connected via a transistor to the resonant circuit. The feedback stage may include a coil and / or a capacitor, which are preferably connected via a transistor to the resonant circuit.

According to the invention, the coding system is formed from at least one digital multiplexing system whose coding inputs are connected to the output signal of the digital counter. The coding system has at least two multiplexing systems. The control input of the first miltiplexing system is connected directly to the control signal output of the digital meter. The control input of the second multiplexing system is connected via an inverter stage, preferably a 'NO-I element, to the control signal output of the digital counter.

An advantage of the invention is that the detection board for the identification system does not require a separate power source, it is simple and reliable.

The subject of the invention is presented in the examples of the drawing, in which Fig. 1 is a schematic diagram of the electric circuit of the detection plate, Fig. 2 - the diagram of the recommended embodiment of the electric circuit of the detection plate and Fig. 3 - electrical waveforms in the circuit of Fig. 2.

Fig. 1 shows a detection plate W containing a resonant circuit formed from the coil L 1 of a capacitor C whose resonant frequency corresponds to the frequency of the electromagnetic field in the controlled zone. The LC resonant circuit of the detection plate located in this electromagnetic field is excited to vibrations, as a result of which alternating voltage is generated on the terminals of the coil and the capacitor connected in parallel.

The diode array Dl, D2 and Cl, Ci capacitors converts the alternating voltage of the resonant circuit into DC voltage, supplied to the integrated TC counting and coding system. To the output of the counting part of the counting and coding system TC there is also an alternating voltage from the resonant circuit through the resistor R, which can be used to control this part. The n-bit counter has 2ⁿ possible output combinations, so a regular 10-bit counter provides 1024 different output states. In the coding part of the counting and coding system TC, only the CS-coded signal that is characteristic of a given detection plate or group of such plates and corresponds to one of the possible initial states of the counting part can be produced. This characteristic CS-coded signal is used for periodic tuning or short-circuiting of the resonant circuit, in a rhythm set by the coding part of the TC counting and coding system. ·

Resonance of the resonant circuit can occur by periodically connecting a capacitor in parallel to the capacitor C or by periodically shorting some of the turns of the coil L. The CS-coded signal can also be used to periodically incorporate a non-linear element into the circuit or to modulate the oscillator signal.

If the detection plate described above is in the electromagnetic field that excites it, then it periodically stops in the rhythm determined by the TC counting and coding system. This is the reason for periodically changing the intensity of the signal sent by the detection plate or the change in energy absorption of this plate, which is easily detectable. Both the specific rhythm of the change in signal strength and the change in energy absorption allow the identification of persons, animals and goods.

Fig. 2 is a schematic diagram of the electric circuit of a detection plate according to the invention. Similarly to the system of Fig. 1, this system contains a resonant circuit formed from the parallel connection of the coil L and the capacitor C, and further the elements of the rectifier system - diodes Dl, D2 and capacitors C1 »C2, which are the source of supply voltage loaded with the charging capacitor C_r and Zener diode Z, which maintains a constant, safe value of the supply voltage.

In contrast to the system of Fig. 1, the system of Fig. 2 includes an additional Oj oscillator, which begins to work when the specified voltage is reached by the supply voltage supplied by the resonant circuit. The Osc Oscillator is built using the known method of two integrated non-I combinational components available on the market, as well as several resistors and capacitors. Oscillator application O₂which supplies counting pulses to the T digital meter has the advantage of providing a signal with a stable frequency, independent of external interference. The pulses from the oscillator are fed to a digital meter Τ »made of an integrated element, which is supplied with direct voltage, obtained from a resonant circuit connected to two commercially available digital integrated multiplexing circuits 26, 21. Multiplexing circuits 20, 21 have control inputs Sal, Sbl, Scl and Sel and Sa2, Sb2, Sc2

12S 7Μ and Se2, as well as a number of Cii and Cif coding inputs. The signals at the control inputs decide on the connection of the corresponding coding input with the terminals of Ul or U2 outputs. The number of coding inputs can be increased by the addition of a third multlexing system.

Fig. 3 illustrates the electrical waveforms present in the circuit of Fig. 2. Signals A, B and C occur on the corresponding output terminals of the digital meter T and are connected to the control inputs Sal, Sbl, Scl or Sa2, Sb2, Sc2 of multiplexing systems 20, 21 The D and E signals are further output signals of the T digital meter that have a special function. Namely, the D signal is fed not to the control input, but to the coding input. This causes the coded signal to be transmitted only at the correct intervals, and in this case when the D signal level is low, as will be explained further below.

The E signal is fed to the Sel input of the first multiplexing circuit 20 and to the element NIE-I 22, and then in the inverted phase to the second multiplexing circuit 21. In this way it is obtained that at a high level of the E signal the source of the coded signal is the first multiplexing circuit 20, while at low E signal level - the second multiplexing system 21.

The coded signals from the outputs of the multiplexing circuits 20, 21 are fed through the NIE-I 23 element to the switching element, which is the keyed transistor 25. The signal F in Fig. 3 is a signal fed through a resistor connected in series and a capacitor connected in parallel to the base of the transistor 25. Spacing time I and II specify the coding provided by the 20 or 21 multiplexing system.

In the given embodiment, the LC resonant circuit is short-circuited during the conduction of transistor 25, caused by the F signal. This is therefore the extreme case of tuning the resonant circuit. The signal generated in the resonant circuit is the signal G of Fig. 3.

The resonant circuit not only produces the coded signal, but also provides the supply voltage for the coding part, so that the shorting of the resonant circuit cannot last too long. This is ensured by the previously described D signal processing, which means that this time does not exceed 50® / by the whole working period._#As a result, G pulse energy packets can be created, which are then used as a synchronization signal for detection systems on both the transmitting and receiving sides. The synchronization signal can be converted into a clock signal which, when synchronized with the coded signal, enters it in the shift register. In this way, an indication of the interference of the detection board signal can be obtained.

In addition to the method of periodically closing the entire resonance circuit, other methods can be used to transfer the signal between the detection plate and the decoding circuit.

For example, with the help of the switching element, an additional coil or capacitor can be connected to the resonant circuit, and it can be turned off. You can also periodically incorporate an additional non-linear element in the form of a diode into the resonant circuit. In the first case, the resonant circuit is tuned according to the code, and in the last case, the resonant circuit produces at least one-third of the frequency if there were two transmit frequencies so far.

The described detection plate can be used both in the identification system with the transmitting system, at the same time fulfilling the role of the receiving system, as well as in the identification system with a separate transmitting and receiving system.

Various modifications to the detection plate described are possible by the appropriate specialist. It is important that the detection board system generates its own counting pulses, and based on them, generates a coded signal in the form of energy pulse blocks, which on the receiving side are used to reproduce the synchronizing signal, for example using a synchronization system. This provides a simple way to obtain for the detection board a coding system that is almost independent of interference and reliable detection of the coded signal on the receiving side.