JPH09251076A - Code generator for transponder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remarkably reduce the possibility of miscounting of a plurality of transponders having the same identification codes. SOLUTION: The code generator 100 for a transponder comprises an identification code storage circuit 110 for storing an identification code for indicating merchandise information to output it, a random number generator 120 for continuously generating random number to output the number as 8-bit pseudorandom code, an error detection code generator 130 for generating error defection code corresponding to a set of the identification code input from the circuit 110 and the random code input from the generator 120, and a power source terminal 150 supplied with a DC power. The generator 100 outputs a response code 140 including the identification code, the pseudo-random code and error detection code.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transponder code generator which is attached to a product or the like and which outputs information on the type and price of the product when receiving an electromagnetic wave from an interrogator.

[0002]

2. Description of the Related Art In a transponder, when an electromagnetic wave from an interrogator is received by a receiving antenna, the modulator modulates the received electromagnetic wave with a response code output from a code generator, and the modulated signal is interrogated from a transmitting antenna. Is to be sent to the vessel.

FIG. 5 is a block diagram showing the structure of a conventional transbonder code generator. In FIG. 5, a conventional code generator 500 stores an identification code indicating product information unique to a transponder, and stores an identification code storage circuit 510 that outputs this and an error detection code corresponding to the identification code. It has an error detection code storage circuit 530 for outputting this and a power supply terminal 550 to which power is supplied, and outputs a response code 540 consisting of the identification code and the error detection code.

FIG. 6 is a timing diagram for explaining the operation of a transponder using the conventional code generator 500.
It shows the exchange of signals between the interrogator and multiple transbonders. In FIG. 6, the electric power 600 of the electromagnetic wave (interrogation signal) output from the interrogator, and n out of many transponders are shown.
-The electromagnetic wave (response signal) power 610 output from the 1st transponder, the electromagnetic wave power 620 output from the nth transponder, the electromagnetic wave power 630 output from the (n + 1) th transponder, and the (n-1) th transponder are operating Mode EN signal 61 indicating whether or not
5, a mode EN signal 625 indicating whether the nth transponder is in operation, a mode EN signal 6 indicating whether the n + 1th transponder is in operation
35 and the interrogator internal signal 650 indicating that the electromagnetic waves from each transponder are received without error and are valid codes, respectively.

Next, operations of the transponder and the interrogator will be described. First, when the interrogator starts transmitting electromagnetic waves (600 in FIG. 6), each transponder receives the electromagnetic waves and starts operating. The operation start timing can be expected to be various times depending on the received electric field strength of each transponder and the variation in the element parameters.

The transponder which has started operation converts the response code 540 output from the code generator 500 into a serial signal, modulates the received electromagnetic wave based on this serial signal, and outputs the modulated electromagnetic wave. This modulation and output are performed intermittently (610, 620, 630 in FIG. 6), and each transponder outputs an electromagnetic wave at its own output timing and output interval.

The response signal (610 in FIG. 6) of the (n-1) th transponder is received by the interrogator, and the error of the identification code included in the received response signal is changed by the error detection code included in the received response signal. If not detected, the interrogator has received the identification code of the (n-1) th transponder normally, and counts it as a normally received transponder (650 in FIG. 6). At this time, the interrogator stops the output of the interrogation signal for a short time in order to inform that the response signal output from the (n-1) th transponder is normally received. When the interrogation signal of this interrogator is stopped, the (n-1) th transponder stops the intermittent output of the response signal and enters the operation stop state (61 in FIG. 6).
5).

Next, when the output timings of the nth and n + 1th transponders overlap with each other (see FIG. 6).
640), the interrogator generally detects an error in the received identification code by the error detection code, recognizes that the reception is not normal, and does not stop outputting the interrogation signal. Therefore, the nth and n + 1th transponders continue to operate as they are.

By repeating the above-mentioned operation, the interrogator receives the identification code of each transponder, counts the transponders which have been normally received, and the response signal cannot be received at all during the specific time. It was judged that the identification code of the responder was received normally.

[0010]

However, when the conventional code generators provided in a large number of transponders have the same identification code, a plurality of transponders accidentally start output at the same time, and If the response signals are coincident but completely overlapped, these response signals are the same, and the interrogator determines that the reception is normal, and counts these transponders as one transponder. There is a problem that the count value becomes lower than the actual number of transponders.

That is, when the output timings of the n-th and n + 1-th transponders having the same identification code and error detection code are coincident but completely overlapped (645 in FIG. 6), the interrogator outputs a response signal. The erroneous reception of (multiple simultaneous reception) cannot be detected by the error detection code, and it is determined that the output of one transponder is normally received, and the output of the inquiry signal is stopped. As a result, the nth and n + 1th transponders enter the deactivated state (62 in FIG. 6).
5, 635).

In general, there are often machines that simultaneously use a large number of transponders having the same identification code and error detection code. For example, when inventory management of the same product packed in a large number is performed, the above-mentioned miscounting is a serious problem.

The present invention solves such a conventional problem and provides a code generator for a transponder capable of significantly reducing the possibility of miscounting a plurality of transponders having the same identification code. The purpose is.

[0014]

In order to achieve the above object, a code generator according to a first aspect of the present invention stores an identification code, and outputs an identification code storage circuit, and a pseudo random number. A pseudo-random code generator that continuously generates a pseudo-random code that changes to a random number, and an error-detecting code generator that generates an error-detecting code for detecting an error in the composite code including the identification code and the pseudo-random code. However, the response code including the identification code, the pseudo random code, and the error detection code is output.

A code generator according to a second aspect is the code generator according to the first aspect, wherein a random number generator that continuously performs a random number generating operation is used as the pseudo random code generator, and a random number output by the random number generator is generated. It is characterized by using a pseudo-random code.

According to a third aspect of the present invention, in the code generator according to the first aspect, as the pseudo random code generator, a clock oscillator that generates a clock and a sequential counter that performs a sequential counter operation according to the clock are used. It is characterized in that the count output by the counter is a pseudo random code.

A code generator according to a fourth aspect stores an identification code, outputs an identification code storage circuit, performs a code generation operation at the time of start-up, and continuously outputs the generated code. , A pseudo-random code generator that is a pseudo-random code that changes in a pseudo-random manner for each generation operation, and an error detection code for detecting an error in a composite code including the identification code and the pseudo-random code An error detection code generator is provided, and a response code including the identification code, the pseudo random code, and the error detection code is output.

According to a fifth aspect of the present invention, in the code generator according to the first aspect, the pseudo-random code generator is a random number generator that performs a random number generating operation at startup and continuously outputs the generated random number. The random number output by the random number generator is a pseudo random code.

According to the code generator of the first aspect, the identification code is output by the identification code storage circuit, and the pseudo random code generator continuously generates the pseudo random code that changes pseudo randomly. This pseudo random code is output, and an error detection code generator is used to generate an error detection code for detecting an error in the composite code consisting of the identification code and the pseudo random code, and this is output to output the identification code and the pseudo random code. By outputting the response code consisting of the code and the error detection code, the probability that the response codes of the multiple transponders having the same identification code are the same can be made very small. The possibility can be significantly reduced.

Further, according to the code generator of the fourth aspect, the identification code storage circuit outputs the identification code, the pseudo random code generator outputs the pseudo random generated at the start-up, and the error detection code. The generator generates an error detection code for detecting an error in the composite code consisting of the identification code and the pseudo random code, outputs it, and outputs a response code consisting of the identification code, the pseudo random code, and the error detection code. As a result, the probability that the response codes in a plurality of transponders having the same identification code will be the same can be made very small, so that the possibility of miscounting the transponders in the interrogator can be significantly reduced.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a transponder will be briefly described. FIG. 1 is a block diagram showing the configuration of a transponder. The transponder shown in FIG. 1 receives a receiving antenna 430 that receives an electromagnetic wave (interrogation signal) from an interrogator (not shown), a rectifying diode 434 that rectifies the received electromagnetic wave, and a DC power by smoothing the rectified output. A capacitor 445 that stores the signal, a code generator 436 that is activated by the supply of the DC power, and that outputs a response code for modulating the received electromagnetic wave to generate a response signal, and a response code that the code generator 436 outputs. A flip-flop 438 for converting to a serial signal, a modulator 440 for generating a response signal by modulating a received electromagnetic wave based on the serial signal, a transmission antenna 432 for transmitting the response signal to an interrogator, and a flip-flop. By controlling the control unit 438, the output interval of the response signal and the operation state (interrogation signal is output intermittently Having a logic circuit 442 for controlling whether or not).

First Embodiment FIG. 2 is a block diagram showing a configuration of a code generator of a transponder showing a first embodiment of the present invention. The code generator 100 shown in FIG. 2 stores an identification code indicating product information and the like, and outputs the identification code.
10 and a random number generator 120 that continuously generates a random number and outputs this random number as an 8-bit pseudo-random code.
And an error detection code generator 130 for generating an error detection code corresponding to the set of the identification code input from the identification code storage circuit 110 and the pseudo random code input from the random number generator 120, and the DC power supply. It has a power supply terminal 150 and outputs a response code 140 including an identification code, a pseudo random code, and an error detection code.

Here, the random number generator 120 is configured to generate a random number each time the transponder intermittently outputs a response signal so that the pseudo random code is updated, and the error detection code generator 130. Is a cyclic redundancy code (CR) used for error detection in an external storage device.
C) is used as an error detection code and is output. The random number generator 120 corresponds to a pseudo random code generator.

Next, the operation of the code generator 100 will be described. When power is supplied from the power supply terminal 150, the identification code storage circuit 110 outputs the stored identification code, the random number generator 120 generates a random number to output a pseudo random code, and the error detection code generator. 130 outputs an error detection code (CRC) corresponding to the set of the input identification code and pseudo random code. Accordingly, the code generator 100 outputs the response code 140 including the identification code, the pseudo random code, and the error detection code.
Here, the random number generator 120 updates the pseudo random code for each intermittent output of the response signal, and accordingly, the error detection code is also updated for each intermittent output of the response signal.

Next, FIG. 3 is a timing chart for explaining the operation of the transponder using the code generator 100 (the code generator 100 is used as the code generator 436 of the transponder shown in FIG. 1). And the interaction of electromagnetic waves with a large number of responders.
In FIG. 3, the electromagnetic wave (interrogation signal) power 200 output from the interrogator, the electromagnetic wave (response signal) power 210 output from the n−1th transponder, and the electromagnetic wave (response signal) output from the nth transponder. ) Power 220 and the electromagnetic wave (response signal) output from the n-th 11th transponder
Power 230, a mode EN signal 215 indicating whether the (n-1) th transponder is in an operating state, a mode EN signal 225 indicating whether the nth transponder is in an operating state, and an (n + 1) th transponder. Mode EN signal 235 indicating whether or not it is in operation
And the internal signal 25 of the interrogator indicating that the electromagnetic waves from each transponder were received without error and the valid code was received.
0 are respectively shown.

Next, the operation of a large number of transponders and interrogators using the code generator 100 will be described. First, when the interrogator starts transmitting electromagnetic waves (200 in FIG. 2), each transponder receives this electromagnetic wave from the receiving antenna 430, rectifies it with the rectifying diode 434, smooths the rectified output with the capacitor 445, and powers it. Accumulate and start operation. The operation start timing can be expected to be various times depending on the received electric field strength of each transponder and the variation in the element parameters.

The transponder which has started the operation converts the response code output from the code generator 100 into a serial signal by the flip-flop 438, modulates the received electromagnetic wave by the modulator 440 based on the serial signal, and outputs the response signal. It is generated and output from the transmission antenna 432.
This modulation and output are intermittently performed by the logic circuit 442 (210, 220, 230 in FIG. 3), and each transponder outputs an electromagnetic wave at its own output timing and output interval.

The response signal (210 in FIG. 3) of the (n-1) th transponder is received by the interrogator, and the error of the identification code and the pseudo random code included in the received response signal is included in the received response signal. If it is not detected by the error detection code, it means that the interrogator has normally received the identification code of the (n-1) th transponder and counts it as a normally received transponder (FIG. 3).
250). At this time, the interrogator stops the output of the interrogation signal only for a short time in order to inform that the response signal output from the (n-1) th transponder is normally received (200 in FIG. 3). When the interrogation signal of this interrogator is stopped, the (n-1) th transponder stops the intermittent output of the response signal by the logic circuit 442 and enters the operation stop state (215 in FIG. 3).

Next, when the output timing of the nth transponder and the output timing of the (n + 1) th transponder are accidentally completely overlapped (2 in FIG. 3).
40) will be described. The response code output from the code generator 100 changes pseudo-randomly by the pseudo-random code for each intermittent output of the response signal. Therefore, the response signal from the nth transponder and n + 1
The probability that the contents of the response signal from the th transponder will be identical is very low. That is, the probability that the pseudo random code of the nth transponder and the pseudorandom code of the (n + 1) th transponder are the same is very low. Therefore, the interrogator can detect erroneous reception (multiple simultaneous reception) of the response signal by the error detection code, recognize that the reception is not normal, and do not stop the output of the electromagnetic wave (interrogation signal) (see FIG. 3). 200).

The response signal from the nth transponder is normally received by the interrogator at the timing shown by 241 in FIG. 3, and the interrogator counts the nth transponder (250 in FIG. 3) to notify the normal reception. , The output of the interrogation signal is stopped only for a short time (200 in FIG. 3), and when this interrogation of the interrogation signal is received, the n-th transponder turns on the logic circuit 4.
The intermittent output of the response signal is stopped by 42, and the operation is stopped (225 in FIG. 3). Similarly, the response signal from the (n + 1) th transponder is normally received by the interrogator at the timing indicated by 242 in FIG. 3, and the interrogator counts the (n + 1) th transponder (250 in FIG. 3) to notify the normal reception. , The output of the inquiry signal is stopped only for a short time (200 in FIG. 3), and when the inquiry signal is stopped, n +
The first transponder stops the intermittent output of the response signal by the logic circuit 442 and enters the operation stop state (2 in FIG. 3).
35).

Here, since the bit length of the pseudo random code is 8 bits, when the response signals of the two transponders having the same identification code completely overlap each other, no error is detected by the interrogator and one error signal is detected. The probability of being counted as a transponder is "1/25
6 ", which is very small. When the outputs of the three transponders are completely overlapped, the probability becomes "1/65536", which is even smaller.

As described above, according to the first embodiment,
For each intermittent output of the response signal, the random number generator 120 updates the pseudo random code, and by adding this pseudo random code to the response code, the probability that the response code in a plurality of transponders having the same identification code will be the same. Can be made very small, so that the miscounting of transponders in the interrogator can be significantly reduced.

The random number generator 12 of the first embodiment described above is used.
0 generates a random number for each intermittent output of the response signal and updates the pseudo-random code, but it may generate a random number at the time of starting by supplying power and output this as a pseudo-random code.

The code length of the pseudo-random code in the first embodiment is 8 bits, but the setting can be changed according to the situation. That is, the probability that the response code of a plurality of transponders will be the same can be reduced as the pseudo random code length becomes longer, but the response code length becomes longer accordingly.
Since the probability that the response signals of the transponders overlap in the interrogator increases, the code length of the pseudo-random code may be set to an optimum value in consideration of these.

Second Embodiment FIG. 4 is a block diagram showing the configuration of the code generator of the transponder showing the second embodiment of the present invention. The code generator 300 shown in FIG. 4 is different from the random number generator 120 in the code generator 100 of FIG. 2 in that it generates a clock having a cycle shorter than the intermittent output cycle of the response signal, and a clock oscillator 320. 8-bit 2 which outputs the count value as 8-bit pseudo-random code
It is provided with the binary counter 325, and outputs a response code 340 including an identification code, a pseudo random code, and an error detection code. The clock oscillator 320 and the binary counter 325 form a pseudo random code generator.

Next, the operation of the code generator 300 will be described. When power is supplied from the power supply terminal 150, the identification code storage circuit 110 outputs the stored identification code, and the binary counter 325 performs a counting operation in synchronization with the clock input from the clock oscillator 320 to count. Output the value as an 8-bit pseudo-random code,
Further, the error detection code generator 130 outputs an error detection code (CRC) corresponding to the set of the input identification code and pseudo random code. This allows the code generator 300
Outputs a response code 340 including an identification code, a pseudo random code, and an error detection code. Here, the binary counter 325 updates the pseudo random code for each intermittent output of the response signal, and accordingly, the error detection code is also updated for each intermittent output of the response signal.

Next, a transponder using the code generator 300 (the code generator 4 of the transponder shown in FIG. 1 will be described.
The operation of the code generator 300 as 36) is exactly the same as in the first embodiment and is illustrated by FIG.

Using the code generator 300, 24 of FIG.
As shown in 0, the operation when the output timing of the nth transponder and the output timing of the (n + 1) th transponder accidentally completely overlap will be described below.

The response code output from the code generator 300 changes with a pseudo random code for each intermittent output of the response signal. This change is due to the clock oscillator 320
This is caused by the difference in the cycle of the response signal and the cycle of the intermittent output of the response signal, and different transponders can be expected to be randomly different from each other. Therefore, the probability that the content of the response signal from the nth transponder and the content of the response signal from the (n + 1) th transponder are the same is very low. That is, the probability that the pseudo random code of the nth transponder and the pseudo random code of the nth transponder are the same is very low. Therefore, the interrogator can detect erroneous reception (multiple simultaneous reception) of the response signal by the error detection code, recognize that the reception is not normal, and do not stop the output of the electromagnetic wave (interrogation signal) (see FIG. 3).
200).

Here, since the binary counter 325 has a bit length of 8 bits, when the response signals of the two transponders having the same identification code completely overlap with each other, the interrogator does not detect an error and outputs one signal. The probability of being counted as one transponder is "1/25
6 ", which is very small. When the outputs of the three transponders are completely overlapped, the probability becomes "1/65536", which is even smaller.

As described above, according to the second embodiment,
Probability that the response code in a plurality of transponders having the same identification code will be the same by updating the pseudo random code by the binary counter 325 for each intermittent output of the response signal and adding this pseudo random code to the response code. Can be made very small, so that the miscounting of transponders in the interrogator can be significantly reduced.

[0042]

As described above, according to the code generator of the transponder of the present invention, the pseudo random code generator adds the pseudo random code updated at every intermittent output of the response signal or at the time of activation to the response signal. By this, the probability that the response code in a plurality of transponders having the same identification code will be the same can be made very small, so that the possibility of miscounting the transponder in the interrogator can be significantly reduced. .

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a transponder.

FIG. 2 is a block diagram showing a configuration of a code generator of the transponder showing the first embodiment of the present invention.

FIG. 3 is a timing diagram illustrating an operation of a transponder using the code generator according to the first and second embodiments of the present invention.

FIG. 4 is a block diagram showing a configuration of a code generator of a transponder showing a second embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of a conventional transponder code generator.

FIG. 6 is a timing diagram illustrating the operation of a transponder using a conventional code generator.

[Explanation of symbols]

 100, 300 Code generator 110 Identification code storage circuit 120 Random number generator 130 Error detection code generator 140, 340 Response code 320 Clock oscillator 325 Binary counter

Claims (5)

[Claims] 1. An identification code storage circuit for storing and outputting an identification code, a pseudo-random code generator for continuously generating a pseudo-random code that changes pseudo-randomly, and the identification code and pseudo-random number. An error detection code generator for generating an error detection code for detecting an error of a composite code including a code, and outputting a response code including the identification code, the pseudo random code, and the error detection code. A code generator for a Lansponder. 2. The pseudo random code generator,
The code generator of the transponder according to claim 1, wherein a random number generator that continuously performs a random number generating operation is used, and the random number output by the random number generator is a pseudo random code. 3. As the pseudo random code generator, a clock oscillator that generates a clock and a sequential counter that performs a sequential counter operation by the clock are used.
The transponder code generator according to claim 1, wherein the count output by the sequential counter is a pseudo random code. 4. An identification code storage circuit which stores an identification code and outputs the identification code, performs a code generation operation at the time of start-up, continuously outputs the generated code, and the code is generated for each generation operation. A pseudo-random code generator that is a pseudo-random code that changes pseudo-randomly, and an error detection code generator that generates an error detection code for detecting an error of the composite code consisting of the identification code and the pseudo-random code, A code generator for a transponder, which outputs a response code including the identification code, a pseudo random code, and an error detection code. 5. The pseudo random code generator,
The transponder according to claim 4, wherein a random number generator that performs a random number generation operation at startup and continuously outputs the generated random number is used, and the random number output by the random number generator is a pseudo random code. Code generator.