JP2855748B2 - Tag communication system - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tag communication system, and particularly, when a plurality of tags arrive at a short time interval within an identification area of an interrogator, interference between the tags is generated. The present invention relates to a tag communication system capable of performing good communication without occurrence.

[Prior Art] A tag communication system that performs communication between a communication device (interrogator) provided on a fixed side and a simple communication device (responder) provided on a mobile side called a tag has been attracting attention. For example, an interrogator emits an interrogation signal by radio waves, light, magnetism, etc., toward an object or a transponder carried by a person who has reached the communicable area of the interrogator, and the non-contact is transmitted by the identification signal returned from the transponder. Used for purposes such as recognizing things or people.

In such a tag communication system, when tags sequentially enter the identification area of the interrogator at short time intervals, interference occurs between the interrogator and the plurality of tags.

In order to solve this, for example, in Japanese Patent Application Laid-Open No. 63-5286, a unique tag number is assigned to each tag in advance, and the tag numbers are sequentially transmitted from the interrogator, and the tags in the identification area are transmitted. Among them, a data transmission method for communicating with a tag having a matching tag number is disclosed (first conventional example). Also, Japanese Patent Application Laid-Open No. 63-1334978 discloses a data transmission method in which an interrogator generates an advance signal having a short time width, and performs communication only with a tag that has received the advance signal. 2 Conventional example).

[Problems to be Solved by the Invention] However, in the first conventional example, when the number of tags to be identified increases, it takes time for the tag number transmitted from the interrogator to make a round, and its own tag A tag that has entered the identification area immediately after the transmission of the number has to wait a relatively long time until its own tag number is transmitted again has a problem that smooth data communication is not performed.

Further, in the second conventional example, when a plurality of subsequent tags enter the identification area while communicating with the tag that has received the advance signal, the plurality of tags receive the restarted advance signal and perform communication. Entering the state may cause interference.

Therefore, the present invention is to solve such a problem, and for tags that sequentially enter the identification area at short intervals,
An object of the present invention is to provide a tag communication system capable of performing prompt communication without causing interference.

[Means for Solving the Problems] To explain the configuration of the present invention, an interrogator 1 provided on a fixed side
A tag communication system for performing communication between (FIG. 1) and a tag 2 provided on a mobile body side, sequentially enters an identification area of the interrogator 1 and sequentially assigns an identification number to the tag 2 which has issued a response signal. The interrogator 1 is provided with an identification number assigning means 3 for transmitting and giving, and a data communication means 4 for sequentially performing data communication between the tags 2 assigned with the identification numbers according to the order of the identification numbers. .

[Operation] In the tag communication system having the above configuration, the plurality of tags 2
Are successively entered into the identification area, the identification numbers are quickly assigned to the tags 2 by the identification number assigning means 3 in the order of entry. The data communication means 4 performs data communication sequentially with respect to the tag 2 to which the identification number has been assigned in accordance with the order of the identification number.

Thus, different identification numbers are quickly assigned to the tags 2 that have entered the identification area, and communication is performed based on the identification numbers. Therefore, no interference occurs between the plurality of tags 2. Further, since the identification numbers are assigned at the time of entry in the order of entry, communication such as the conventional example in which communication is not started until the tag number completes does not occur, and quick communication is possible.

Embodiment FIG. 1 shows the overall configuration of a communication system according to the present invention.
In the figure, the interrogator 1 provided on the fixed side includes an identification number assigning circuit 3, a data communication circuit 4, and a signal processing circuit 5. Identification number assigning circuit 3 and data communication circuit 4
Have the same configuration, and include high-frequency oscillators 31 and 41, modulators 32 and 42, demodulators 33 and 43, circulators 34 and 44, and antennas 35 and 45, respectively. The high-frequency oscillators 31 and 41 output carrier waves having different frequencies.

In the identification number assigning circuit 3, the identification number data output from the signal processing circuit 5 is transmitted from the antenna 35 via the circulator 34 modulated by the modulator 32. The identification number assigning circuit 3 also transmits a monitoring signal while not receiving a response signal from the tag 2 described later. The response signal from the tag 2 is received by the antenna 35, demodulated by the demodulator 33 via the circulator 34, and taken into the signal processing circuit 5.

The data communication circuit 4 modulates a data request signal or write data output from the signal processing circuit 5 by the modulator 42 and transmits the modulated data request signal or write data from the antenna 45 via the circulator 44. Also, the read data from the tag 2 is transferred to the antenna 45.
And demodulated by the demodulator 43 via the circulator 44 and input to the signal processing circuit 5.

On the other hand, each tag 2 includes an identification number capturing circuit 6, a data communication circuit 7, and a signal processing circuit 8. The identification number capturing circuit 6 and the data communication circuit 7 have the same configuration.
Antennas 62, 71, modems 62, 72, amplifier 63, respectively
Consists of 64, 73 and 74.

When the tag 2 enters the identification area of the interrogator 1, the antenna 61 receives the monitoring signal from the interrogator 1, which is demodulated by the modem 62 and input to the signal processing circuit 8 via the amplifier 64. The signal processing circuit 8 to which the monitoring signal has been input emits a response signal, which reaches the modem 62 via the amplifier 63. The modulator / demodulator 62 modulates the monitor signal received by the antenna 61 based on the response signal and sends the modulated signal to the interrogator 1. The antenna 61 also receives the identification number data from the interrogator 1 and the data is demodulated and input to the signal processing circuit 8 for storage.

The data communication circuit 7 receives the data request signal or the write data from the interrogator 1 through the antenna 71 and
After demodulation, the signal is taken into the signal processing circuit 8 via the amplifier 74. The signal processing circuit 8 outputs read data in response to the data request signal. The read data is sent to the modem 7 via the amplifier 73. The modulator / demodulator 7 modulates the carrier reaching the antenna 71 by the read data. Interrogator 1
Send it back to

The operation of the signal processing circuit 5 of the interrogator 1 in a case where a plurality of tags 2 successively enter the identification area at short intervals in the tag communication system having such a configuration will be described with reference to FIG.

In the figure, counters K and N are reset in steps 101 and 102, respectively. In step 103, interruption is enabled, and in step 104, the counter value (N) of the counter N is set.
Wait until is greater than zero. In the case of the present embodiment, the monitoring signal uses an unmodulated wave, and the carrier wave emitted from the high-frequency oscillator 31 is transmitted from the antenna 35 as it is.

When the first tag 2 enters the identification area of the interrogator 1 and emits a response signal, the response signal is input to the signal processing circuit 5, and an interrupt program from step 201 on is executed. That is, in step 201, the counter N is counted up and this count value (N) is transmitted to the tag 2 as an identification number.

When the count value (N) of the counter N becomes larger than 0 due to the execution of the interrupt program, steps 105 and the subsequent steps are executed. That is, in step 105, the count K
Is counted up, and in step 106, data is requested from the tag 2 having the same identification number as the count value (K), and the data is read from this. Subsequently, write data is sent to the tag 2 (step 107), and interrupts are prohibited (step 108). In this case, the identification numbers of the tags 2 are added to the heads of the write data and the read data by the respective signal processing circuits 5 and 8, so that communication with different tags 2 is prevented.

If a new tag 2 enters the identification area and issues a response signal during the execution of steps 105 to 107, the interrupt program is executed again and the counter N is counted up.
The same identification number as the count value (N) is transmitted to tag 2 and given.

In this way, when a new tag 2 enters and a response signal is issued during execution of steps 105 to 107, the counter N is counted up each time, and an identification number is sequentially transmitted to each tag 2 in the order of entry. Is done.

As a result, when the interrupt is prohibited (step 108) and the counter K is compared with the counter N in step 109, if a new tag 2 enters during the execution of steps 105 to 107, the count value (K) , (N) do not match, and the steps 103 and subsequent steps are executed again to read and write data to the newly entered and waiting tag 2.

When the data exchange with the group of tags 2 entering the identification area is completed, the count value (K),
(N) matches and returns to steps 101 to 104 to prepare for the next new tag entry.

The reason why the interrupt is prohibited in step 108 is that data communication is not performed with the tag 2 even if an interrupt occurs and an identification number is assigned while returning from step 109 to step 101.

FIG. 3 shows an example of the timing of the above-described identification number assignment and data communication. In the figure, tag 2A, tag 2B, and tag 2C enter continuously at short intervals, and after a while, tag 2D and tag 2D
This shows a case where 2E enters continuously.

As is known, while the tag 2A is assigned an identification number and the data is being communicated, each of the tags 2A is
When B and tag 2C enter, they will be immediately identified number,
Are immediately added, and when the communication with the tag 2A is completed, the data communication with the tag 2B and the tag 2C is subsequently performed.

After the data communication is completed for the tags 2A to 2C, if there is a time before the next tag entry, the counters K and N are reset, and the tags D and E which enter next continuously are identified again. A number is assigned, and data communication is performed.

As described above, the identification numbers are sequentially assigned to the tags 2 entering the identification area of the interrogator 1 at short intervals by the identification number assigning circuit 3 in the order of entry, and in parallel with this, the data communication circuit 4 Data communication is performed with the tag 2 assigned with the identification number. Thus, communication is performed without causing interference with the plurality of tags 2 that have entered the identification area, and the time until the start of communication with each tag 2 is greatly reduced.

In this embodiment, after communication with all tags that have entered the identification area is completed, if there is a period of time before entry of the next tag, the identification number is reset. A degree is enough.

Further, in the present embodiment, a method in which different frequencies are used for the identification number assigning circuit 3 and the data communication circuit 4 is disclosed, but the same frequency may be used by changing the polarization direction of radio waves. The effect is obtained.

In addition, the present invention can of course be applied to a case where data communication is exclusively for reading data from a tag.

[Effects] As described above, according to the tag communication system of the present invention, reliable and quick data communication can be performed for a plurality of tags that continuously enter the identification area in a short time. It can be suitably used for a periodic automatic reading device and the like.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the overall configuration of a tag communication system, and FIG.
The figure is a flowchart of the operation of the signal processing circuit of the interrogator.
The figure is the operation time chart. 1 Interrogator 2 Tag 3 Identification circuit (identification means) 4 Data communication circuit (data communication means)

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H04B 1/59 G01S 13/74 H04B 7/26 B23Q 41/00

Claims (1)

(57) [Claims] In a tag communication system for performing communication between an interrogator provided on a fixed side and a tag provided on a mobile body, a tag which sequentially enters an identification area of the interrogator and issues a response signal is provided. The interrogator is characterized in that the interrogator is provided with an identification number assigning means for sequentially sending and assigning an identification number, and a data communication means for sequentially performing data communication with a tag assigned the identification number according to the order of the identification number. Tag communication system.