JP3191673B2 - Communication system and transponder for non-contact data reader - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication system for a non-contact data reading apparatus for reading data from a transponder attached to an article such as a product mainly by using radio waves in the UHF and microwave millimeter wave bands. Things.

[0002]

2. Description of the Related Art Conventionally, a communication method is disclosed in
A communication system described in Japanese Patent Application No. 82778 is known.

In FIG. 14, a communication area 2 of an interrogator 1
The transponder 4 enters the communication area 2 while the interrogator 1 and the transponder 3 are communicating with each other.

FIG. 15 is an explanatory diagram of a communication state at this time. The interrogator 1 transmits a communication start request signal R0 at the start of communication.
At the end of the communication, a communication end request signal RN is transmitted (FIG. 15).
(A)). After receiving the communication start request signal R0 from the interrogator 1 at time t1, the transponder 3 starts communication with the interrogator 1 (communication signal A0 shown in FIG. 15B), and at time ts, the communication end request signal RN. And stops the communication operation for the time T.

On the other hand, the transponder 4 receives the communication start request signal R0 at time t2 and starts communication (communication signal B0 shown in FIG. 15C), but the transponder 3 stops the communication operation at time t2. Therefore, the communication start request signal R0 is not received, and the communication between the transponder 4 and the interrogator 1 is performed.

[0006]

In the above conventional communication system, when a plurality of transponders enter the communication area of the interrogator at the same time, the transponders simultaneously perform a communication operation. Communication was difficult.

A communication system according to the present invention solves the above-mentioned problem. Even when a plurality of transponders exist in a communication area of an interrogator, non-contact data capable of reading data from the plurality of transponders is provided. It is intended to realize a reading device.

[0008]

According to the present invention, a transponder transmits a response signal at a fixed or pseudo-random time interval different from other transponders, and the transponder transmits the response signal at an interrogator. Receive and demodulate and read response data. Also, the self-identification information included in the response data read by the interrogator is transmitted as confirmation identification information included in the question data,
When the self identification information and the confirmation identification information match, the response operation is stopped. Also, if no response signal is received from the transponder for a certain period of time, the interrogator stops the reading operation. When the transponder goes out of the communication area, the response operation is stopped. Also, the transponder has a group number as self-identification information, the interrogator counts the number of response signal receptions for each group number, and sets the maximum value to the number of transponders having the group number. Further, the interrogator has a plurality of transmitting / receiving means, and replaces the transmitting / receiving means for each reading operation.

[0009]

[0010]

[0011]

[0012]

[0013]

[0014]

[0015]

[0016]

[0017]

[0018]

[0019]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 12 and Table 1.

(Embodiment 1) FIG. 1 is a block diagram showing a contactless data reading apparatus according to Embodiment 1 of the present invention.

An interrogator 100 reads data from a transponder, and comprises an interrogation signal generator, a transmitter / receiver, a response signal demodulator, and a controller for controlling the interrogator 100.

Reference numeral 101 denotes an interrogation signal generating means which generates an interrogation signal and generates an oscillator 105 for generating a signal of the frequency transmitted by the interrogator 101, a distributor 106 for dividing the output of the oscillator 105, and an output of the oscillator 105. Amplifier 1 to amplify
07.

Reference numeral 102 denotes a transmitting / receiving means, and a circulator 108 for transmitting an inquiry signal and receiving a response signal.
And an antenna 109.

Reference numeral 103 denotes a response signal demodulation means, which is a mixer 110 for frequency-converting the received response signal, and a distributor 10.
, Mixer 1110 for amplifying the signal from
And a demodulation unit 113 for demodulating the output of the low-pass filter 112 for extracting a low-frequency component from the output signal.

On the other hand, reference numeral 120 denotes a transponder, which carries out a response operation by incorporating self-identification information, and comprises a reflection modulator, a controller, a response synchronization signal generator, and a storage.

Reference numeral 121 denotes a reflection modulation means, which is an antenna 125 for modulating and reflecting a received interrogation signal, and a switch 126 for switching a load connected to the antenna 125.
And a matching terminator 127 for absorbing the input signal, and a reflector 128 for reflecting the input signal.

Reference numeral 122 denotes control means, which comprises a CPU 130 for controlling the response operation of the transponder 120.

Reference numeral 123 denotes a response synchronizing signal generating means, which comprises a timer circuit 131 for generating a response synchronizing signal at a constant or pseudo-random time interval.

Reference numeral 124 denotes a storage unit, and a memory 132 for storing data including self-identification information of the transponder 120.
The interrogator 100 and the responder 1 having the above configuration
20 will be described.

First, the interrogator 100 generates a frequency signal interrogation signal unique to the interrogator 100 by the oscillator 105 and
After the signal is amplified by the amplifier 107 via
The circulator 108,
The transponder 1 is transmitted from the transmitting / receiving means 102 via the antenna 109.
20.

On the other hand, in the transponder 120, the CPU 130 of the control means 122 synchronizes with the response synchronizing signal generated by the timer circuit 131 which is the response dynamic synchronizing signal generating means 123 and stores it in the memory 132 of the storage means 124. The response data is created using the stored self-identification information, and the switch 126 is switched and controlled according to the response data.

When the switch 126 is connected to the matching terminator 127, the interrogation signal received by the antenna 125 is absorbed by the matching terminator 127. On the other hand, when the switch 126 is connected to the reflector 128, the interrogation signal received by the antenna 125 is reflected by the reflector 127 and re-emitted from the antenna 125.

Therefore, according to the response data, the control means 12
By switching the switch 126 with 2, the antenna 12
The signal re-emitted from 5, i.e. the response signal, is ASK modulated with the response data.

Next, the interrogator 100 receives the response signal from the transponder 120 via the antenna 109 and the circulator 108 which are the transmission / reception means 102, and
At 0, the signal is converted to a baseband signal, and demodulated by the demodulation unit 113 via the LPF 112 to obtain response data.

FIG. 2 is a timing chart of the interrogation signal, the response signal, and the received response data signal when there are transponders 120A and 120B having the response synchronizing signal generating means 123 operating at different timings in the communication area of the interrogator. , (A),
(B) is a response signal of each of the transponders A and B, and (c) is reception response data of the interrogator. The non-contact data reading operation will be described with reference to FIG.

First, the transponder 120A responds to the response signals a1,
a2 and the transponder 120B transmits response signals b1 and b2.

On the other hand, the interrogator 101 outputs the response signals a1, b
Since 1 is received at the same time, demodulation cannot be performed and response data cannot be obtained.

On the other hand, a response synchronization signal generating means 1 is provided for each transponder.
Since the timing at which the 23 generates the response synchronization signal is different, there is no response signal overlapping with the response signal a2 of the transponder 120A, and it is received as the received response signal r2, and the self-identification information of the transponder 120A is read by demodulation. Similarly, the response signal b2 of the transponder 120B is the reception response signal r
3 and the self-identification information of the transponder 120B is read.

As described above, according to the communication method of the non-contact data reading device of the first embodiment of the present invention, the timing at which the response synchronization signal generating means 123 generates the response synchronization signal differs for each transponder. Even if a plurality of transponders exist in the communication area of the transponder, the interrogator can read contactless data from each transponder.

(Embodiment 2) FIG. 3 shows a block diagram of a contactless data reading apparatus according to Embodiment 2 of the present invention.

Reference numeral 200 denotes an interrogator.
1. The transmission / reception means 102, response signal demodulation means 103, and reception response signal output terminal 104 have the same configuration as that shown in FIG. The interrogator 200 of FIG. 3 is different from the interrogator 100 of FIG. 1 in that an interrogation signal modulating unit 201 including a mixer 203 for modulating the interrogation signal generated by the interrogation signal generating unit 101 with interrogation data is newly provided. It is a point.

On the other hand, a transponder 210 is a response synchronizing signal generating means 123 and a storage means 124 similar to those shown in FIG. 1, and a reflection modulation means, a control means, a detection demodulation means and a communication area detecting means different from those shown in FIG. Consists of

Reference numeral 211 denotes a reflection modulation means for receiving the interrogation signal, modulating and reflecting the same, and transmitting the interrogation signal to a detection / demodulation means described later.
28.

Reference numeral 213 denotes a detection and demodulation means for demodulating interrogation data from the received interrogation signal. The detection and demodulation means comprises a detection diode 220, a capacitance element 221, a load resistor 222, an amplifier 223 for amplifying the detected signal, and a comparator 224.

Reference numeral 214 denotes a communication area detecting means for detecting a communication area from the detected signal level.
It comprises a reference voltage 231.

FIG. 4 is a timing chart of the response signal (a) received by the interrogator 200, the transmission response signal (b) of the transponder 210, and the received interrogator transmission interrogation signal (c).

The operation of the non-contact data reading device having the above configuration will be described. When the transponder 210 enters the communication area of the interrogator 200, the reflection modulating means 21 of the transponder 210
1, the interrogation signal from the interrogator 200 is detected by the detection / demodulation means 213 via the first detection signal demodulation means 1, and when the detected signal voltage exceeds the reference voltage 231 of the communication area detection means 214, the comparator 23
From 0, a communication area detection signal is output, and the transponder 210 starts a response operation.

Next, the control means 212 receives the communication area detection signal, synchronizes with the response synchronization signal generated by the response synchronization signal generation means 123, and reflects the response data including the self-identification information in the storage means 124. It controls the modulating means 211 to transmit a response signal.

The interrogator 200 creates question data using the self-identification information included in the received response signal as confirmation identification information, modulates the interrogation signal using the question data, and transmits it to the transponder 210 as a reception confirmation signal. .

The transponder 210 detects and demodulates the received acknowledgment signal by the detection and demodulation means 213 to obtain interrogation data.
When the question data includes the same confirmation identification information as the self-identification information stored in the storage unit 124, the response operation ends.

As described above, according to the communication method of the non-contact data reading device of the second embodiment, even if a plurality of transponders exist in the communication area of the interrogator, the interrogators are transmitted from each transponder. The data can be read, and the transponder whose data has been read by the interrogator ends the response operation, whereby the data reading operation of the other transponders is made more efficient.

(Embodiment 3) FIG. 5 is a timing chart of an interrogation signal and a response signal representing an operation state of a communication system of a contactless data reading apparatus according to Embodiment 3 of the present invention. The interrogator transmission interrogation signal (a), the reception response signal (b), the transponder A response signal (c), and the response B response when the transponders A and B exist in the communication area of the interrogator having the configuration of FIG. The signal (d).

The interrogator starts transmitting the interrogation signal simultaneously with the start of the reading operation. The transponders A and B start the response operation by receiving the interrogation signal, and transmit the response signal according to the response synchronization signal. The response signals a1 and b1 cannot be demodulated because they are received by the interrogator at the same time, but the response signals a2 and b2 are r2 and r3, respectively, because the time intervals of the response start signal generating means 123 are different between the transponders A and B. And the acknowledgment signals AK1 and AK2 are transmitted from the interrogator, and the transponders A and B end the response operation in response to the acknowledgment signals AK1 and AK2, respectively.

After transmitting the acknowledgment signal AK2, the interrogator
If no response signal is received during the time T, the reading operation ends.

As described above, the interrogator 300 is provided by the communication method of the non-contact data reading device according to the third embodiment of the present invention.
Can efficiently read data from all transponders existing in the communication area.

(Embodiment 4) FIG. 6 is a block diagram showing a configuration of an interrogator according to a communication system of a contactless data reading apparatus according to Embodiment 4 of the present invention.

An interrogator 400 is an interrogator 2 shown in FIG.
This is almost the same configuration as 00. 6 differs from the configuration in FIG. 3 in a transmission / reception unit 401 and a control unit 402.

The transmission / reception means 401 transmits an inquiry signal and receives a response signal.
04, circulators 405, 406, 407, and antennas 408, 409, 410. That is,
The switch 403 controls the output of the interrogation signal modulating unit 201 by each of the circulators 405 and
Through antennas 408, 409, 41
0 is selectively transmitted. The switch 404 is configured to select a reception signal from the antennas 408, 409, and 410 input through the circulators 405, 406, and 407 according to a control signal of the control unit 402, and transmit the signal to the response signal demodulation unit 103. Have been.

FIG. 7 is a diagram showing a communication area of the interrogator 400, wherein a, b, and c are antennas 408, 409, and 408, respectively.
A communication area when 410 is used is shown.

The operation of the above configuration will be described. In the first reading operation, the interrogator 400
The switch 403 and the switch 403 are controlled by the control signal of the control unit 402 so that the interrogation signal modulation unit 201 and the response signal demodulation unit 103 are connected to the circulator 405 (antenna 408).
Switch 404 to read the transponder in the communication area of FIG. 7a. By receiving the response signal from the transponders existing in the communication area a and transmitting the acknowledgment signal to the response request signal, the reading is performed from all the transponders in the communication area a.

In the second and third read operations, the read operation of the transponder is similarly performed for the communication areas b and c, respectively.

As described above, by providing a plurality of antennas and a switch for switching the antennas, and by switching the communication area for each frame, it becomes possible to read from the transponder over a wide communication area.

(Embodiment 5) FIG. 8 is a timing chart of an interrogation signal and a response signal at the time of a data reading operation by the communication method of the contactless data reading apparatus according to Embodiment 5 of the present invention. When the transponders A and B exist in the communication area of the interrogator having the configuration of FIG. 3, the transmission interrogation signal (a), the reception response signal (b), the response signal (c) of the interrogator A, It is a response signal (d) of the transponder B.

As shown in FIG. 8A, the interrogator 200 transmits an interrogation signal modulated with the response request data as the response request signal Q1 at the start of the reading operation.

Next, the transponders A and B correspond to FIG.
As shown in FIG. 8D, the response request signal Q1 is received, the response operation is started, and the response signal is transmitted in synchronization with the response synchronization signal.

The response signals a1 and b1 cannot be demodulated because they are received by the interrogator at the same time. However, the response signals a2 and
b2 is received as r2 and r3 (FIG. 8 (b)), respectively, and acknowledgment signals AK1 and AK2 (FIG. 8 (a)) are transmitted from the interrogator, and the responders A and B end the response operation.

As described above, according to the fifth embodiment of the present invention, the interrogator transmits the response request signal at the start of the reading operation, and the transponder starts the response operation by the response request signal. The operation of the transponder can be performed synchronously.

(Embodiment 6) FIG. 9 is a timing chart of an interrogation signal and a response signal at the time of a data reading operation by a communication method of a contactless data reading apparatus according to Embodiment 6 of the present invention. In the communication area of the interrogator 200 having the configuration of FIG.
These are the reception interrogation signal (a) and the response signal (b) of the transponder when the transponder exists.

As shown in FIG. 9A, the interrogator 200 transmits an interrogation signal modulated with the response request data as the response request signal Q1 at the start of the reading operation.

The transponder 210 receives the response request signal Q1 and starts a response operation, and transmits the response signal in synchronization with the response synchronization signal as shown in FIG. 9B.

When the transponder moves out of the communication area of the interrogator, the interrogation signal is no longer detected by the communication area detecting means, and the transponder stops responding.

As described above, according to the sixth embodiment of the present invention, the response operation is stopped when the user goes out of the communication area without receiving the reception confirmation signal due to the movement of the transponder.
Normal operation can be performed in the next reading operation.

(Embodiment 7) FIG. 10 is a timing chart of an interrogation signal and a response signal during a data reading operation by a communication method of a contactless data reading apparatus according to Embodiment 7 of the present invention. In the case where the transponders A and B exist in the communication area of the interrogator 200 having the configuration of FIG. 3, (a) is an interrogation signal, (b) is a response signal of the transponder A, and (c) is a response signal of the transponder B. This is a response signal.

The interrogator transmits a response request signal at one-frame time intervals. The transponders A and B transmit response signals at a time interval generated by the response synchronizing signal generating means from the reception of the response request signal.

The transponder A transmits a response signal a1 after a time TA1 with respect to the response request signal Q1, and transmits a response signal a2 after a time TA2 with respect to the response request signal Q2.

The transponder B transmits a response signal b1 after a time TB1 with respect to the response request signal Q1, and transmits a response signal b2 after a time TA1 with respect to the response request signal Q2.

The response signals a1 and b1 cannot be demodulated because they are received by the interrogator at the same time, but the response signals a2 and b2 are received and demodulated by the interrogator because the transmission timings from the transponders are different. Get the data.

As described above, according to the seventh embodiment of the present invention, the interrogator transmits the response request signal at the start of the reading operation, and the transponder starts the response operation by the response request signal. The operation of the transponder can be performed synchronously.

(Eighth Embodiment) FIG. 11 is a timing chart of an interrogation signal and a response signal at the time of a data reading operation by a communication method of a contactless data reading device according to an eighth embodiment of the present invention. When the transponders A and B exist in the communication area of the interrogator 200 having the configuration shown in FIG. 3, (a) is an interrogation signal, (b) is a response signal of the transponder A, and (c) is a transponder B. Is a response signal.

In response to the response request signal Q1 of the interrogator 200, the transponder A transmits a response signal a1. The interrogator receives the response signal a1 and transmits an acknowledgment signal AK1.
The transponder A that has received the acknowledgment signal AK1 ends the response operation.

Similarly, transponder B transmits response signal b1 and receives acknowledgment signal AK2, thereby ending the response operation.

The interrogator ends the reading operation when the response signal to the response request signal Q2 is not received for one frame time.

As described above, according to the eighth embodiment of the present invention, all the transponders existing in the communication area can be read.

(Embodiment 9) FIG. 12 is a timing chart of an interrogation signal and a response signal of the communication system of the contactless data reading apparatus according to Embodiment 9 of the present invention. In the communication area of the interrogator having the configuration shown in FIG. 3, there are four transponders having group numbers as self-identification information, four for group number 1, four for group number 2, and four for group number 3. In some cases, (a) is an interrogation signal, and (b) is a reception response signal of the interrogator. (Table 1) is a result table of the reading operation in three frames.

[0085]

[Table 1] In response to the response request signal, each transponder transmits the response signal after a time interval generated by the response synchronization signal generating means.

For the response request signal, the group number 1
Response signal of group number 2 three times,
The response signal of group number 3 is received three times. The results for the response request signals Q2 and Q3 are as shown in Table 1.

From the results of the above three frames, it is assumed that there are four transponders having group number 1, four transponders having group number 2, and four transponders having group number 3.

As described above, the transponder has a group number as self-identification information, counts the number of times a response signal is received in one frame for each group number, and obtains the maximum value in M frames. The number of transponders existing in the communication area can be obtained for each group number.

(Embodiment 10) FIG. 13 shows a communication area of a communication type interrogator of a contactless data reading apparatus according to Embodiment 10 of the present invention. The communication areas a, b, and c shown in FIG. 13 are provided for the antennas 408, 409, and 410 of the interrogator having the configuration shown in FIG. The transponder stores the group number as self-identification information.

The interrogator switches the communication area for each frame to change the direction in which the interrogator irradiates the interrogator with the interrogation signal, and counts the number of receptions of the response signal in the frame for each group number.

As described above, according to the tenth embodiment of the present invention, by switching the irradiation direction of the interrogation signal to the transponders, it is possible to reduce the influence of the positional relationship between the transponders, etc. The number of transponders can be counted.

[0092]

As described above, according to the present invention, even when a plurality of transponders exist in the communication area of the interrogator, the advantageous effect that non-contact data can be read from each transponder can be obtained. Can be

[Brief description of the drawings]

FIG. 1 is a block diagram of a contactless data reading device according to a first embodiment of the present invention;

FIG. 2 is a communication timing chart of a communication method of the contactless data reading device according to the first embodiment of the present invention.

FIG. 3 is a block diagram of a contactless data reading device according to a second embodiment of the present invention;

FIG. 4 is a communication timing chart of a communication method of the contactless data reading device according to the second embodiment of the present invention;

FIG. 5 is a communication timing chart of a communication method of the contactless data reading device according to the third embodiment of the present invention.

FIG. 6 is a block diagram of an interrogator of a contactless data reading device according to a fourth embodiment of the present invention.

FIG. 7 is a communication area diagram of an interrogator of a contactless data reading device according to a fourth embodiment of the present invention.

FIG. 8 is a communication timing chart of a communication method of a contactless data reading device according to a fifth embodiment of the present invention.

FIG. 9 is a communication timing diagram of a communication method of the contactless data reading device according to the sixth embodiment of the present invention.

FIG. 10 is a communication timing chart of a communication method of the non-contact data reading device according to the seventh embodiment of the present invention.

FIG. 11 is a communication timing chart of a communication method of the non-contact data reading device according to the eighth embodiment of the present invention.

FIG. 12 is a communication timing chart of a communication method of the contactless data reading device according to the ninth embodiment of the present invention;

FIG. 13 is a directional diagram of an interrogator of the contactless data reading device according to the tenth embodiment of the present invention.

FIG. 14 is a layout diagram of a conventional non-contact data reading device.

FIG. 15 is a communication timing diagram of a communication method of a conventional contactless data reading device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 interrogator 101 interrogation signal generation means 102 transmission / reception means 103 response signal demodulation means 104 control unit 120 transponder 121 reflection modulation means 122 control means 123 response synchronization signal generation means means 124 storage means 126 switch 127 matching terminator 128 reflector

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Fukagawa 1006 Kazuma Kadoma, Kadoma-shi, Osaka Matsushita Electric Industrial Co., Ltd. (56) References JP-A-56-73944 (JP, A) JP-A-7- 303111 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H04B 1/59 G01S 13/75-13/79 H04B ⁷ /24-7/26

Claims (7)

(57) [Claims] 1. A method for storing data including self-identification information.
Storage means, emitting a response synchronous signal at a constant or pseudo random time intervals
A response synchronizing signal generating means for generating the response synchronizing signal with reference to the data;
Control means for controlling an operation, and the self-identification information is controlled by the control means,
The response signal that is reflected and modulated with the response data
A transponder having projection modulation means, wherein the interrogator demodulates the interrogation signal transmitted by the interrogator, and
The detection and demodulation means to be obtained and the interrogation signal
Communication area detecting means for detecting the self-identification information received by the interrogator from the responder.
Information as an acknowledgment signal and received by the transponder
The reception confirmation signal is self-identifying information of the transponder and
If they are the same or communication area cannot be detected
The response operation is stopped when
Bowl . 2. The interrogator transmits an interrogation signal, and the responder
Response synchronization signal generated at fixed or pseudo-random time intervals
Self-identification at different time intervals from other transponders in synchronization with the
Transmitting a response signal consisting of data containing different information,
The interrogator demodulates the received response signal to obtain the data.
Communication method of non-contact data reading device characterized by the fact that
A formula, the transponder may communicate collar of the interrogator from the interrogation signal
A means for detecting that the self-identification information is received by the interrogator from the responder.
Information as an acknowledgment signal and received by the transponder
The reception confirmation signal is self-identifying information of the transponder and
If they are the same or communication area cannot be detected
Response operation is stopped when the
Communication method of touch data reading device . 3. The interrogator starts transmission of an interrogation signal at the same time as the start of the reading operation, and stops the transmission of the interrogation signal when the response signal from the transponder is not received for a certain period of time, and ends the reading operation. The communication system for a non-contact data reading device according to claim 2, wherein: 4. A transmission / reception means of an interrogator includes a plurality of antennas and a switching means for switching connection to the antennas, and the interrogator switches the communication area by replacing the antenna every reading operation. A communication method for the non-contact data reading device according to claim 3. 5. The interrogator transmits an interrogation signal, and the responder transmits
Response synchronization signal generated at fixed or pseudo-random time intervals
Self-identification at different time intervals from other transponders in synchronization with the
Transmitting a response signal consisting of data containing different information,
The interrogator demodulates the received response signal to obtain the data.
Communication method of non-contact data reading device characterized by the fact that
A formula, as a response request signal to the operation start the interrogator is read
Transmitting an interrogation signal demodulated with the response request data;
The device starts a response operation by detecting the response request signal.
Starting, transmitting the response signal to an interrogator,
A reception acknowledgment signal indicating the self-identification information received from the transponder.
And the acknowledgment signal received by the transponder
Is the same as the self identification information of the transponder
Non-contact data reading characterized by stopping response operation
Communication method of the capture device . 6. A communication area detecting means for detecting that the transponder is in the communication area of the interrogator based on an interrogation signal, and detecting that the transponder has entered the communication area by the communication area detecting means. If you do, start the response operation,
6. The communication method according to claim 5, wherein the response operation is terminated when the communication area is no longer detected. 7. The interrogator transmits an interrogation signal, and the responder
Response synchronization signal generated at fixed or pseudo-random time intervals
Self-identification at different time intervals from other transponders in synchronization with the
Transmitting a response signal consisting of data containing different information,
The interrogator demodulates the received response signal to obtain the data.
It is a communication method of a non-contact device, characterized in that the interrogator as a response request signal at the start of the reading operation
Question demodulated with response request data at one frame time interval
Transmitting a signal, wherein the transponder detects the response request signal
To start a response operation, and the response
Send a signal to the interrogator, which interrogates the previous
Demodulating the response signal, wherein the transponder has a group number as the self-identification information.
And the interrogator is received during one frame time interval
The response signal is counted for each group number, and
After the program time interval, the maximum value of the count is
Contact number characterized by the number of transponders having loop numbers
Device communication method .