JPH04208890A - Communication method for moving body recognizer - Google Patents

Abstract

PURPOSE:To enable processing in high speed even increasing the number of responder by returning a response signal after a multitude of responders existing in the area available of communication with questioning device received a single question signal. CONSTITUTION:A questioning device 4 transmits a question signal Q to detect responders existing in the area S available of communication. It is formed to transmit necessary number of timing signals T1, T2..., T7 to indicate response timing to the responders after the transmission. After the questioning device 4 sends off the first timing signal T1, it is to receive a response signal from the responder and a response signal A1 from the first responder 1 is received. The existence of the first responder can be known by receiving it. Same is true for the processing of the second timing signal T2. By processing in this manner, high speed processing is possible even with increase in the number of responders and timing signals to transmit.

Description

[Detailed description of the invention]

[00011

[Industrial Field of Application] The present invention relates to a communication system for a mobile object identification device that transmits and receives information from an interrogator to a transponder attached to a mobile object using non-contact communication means such as radio waves. It is used in vehicle identification systems, logistics monitoring systems, etc. [0002] Conventionally, mobile object identification devices using microwaves have been put into practical use. In this device, an interrogator installed at a place where the moving object passes continuously or intermittently sends an interrogation signal to the transponder attached to the moving object to detect the transponder. . Here, if there is only one transponder within the communicable area,
This transponder returns a response signal after receiving the interrogation signal. The response signal usually includes the transponder's identification number or data stored inside the transponder, and the interrogator detects and identifies the transponder by receiving this response signal. be. [0003]

However, when a plurality of transponders exist in a communicable enoa, the plurality of transponders simultaneously return response signals in response to one interrogation signal. Therefore, on the interrogator side, a plurality of response signals are received at the same time, and the response signals interfere with each other, resulting in a problem that normal reception operations cannot be performed. [00041 The above-mentioned problems in the conventional communication system will be explained with reference to FIG. In the illustrated state, three transponders 1. 2. 3 exists. At this time, interrogator 4 and responder 1. 2.
The communication state of No. 3 is as shown in the time chart of FIG. In the figure, Q is an interrogation signal sent by the interrogator 4, Al,
A2. A3 is the transponder 1. 2. 3 is the response signal sent. In the conventional communication method, all transponders 1. 2. 3 receives the interrogation signal Q from the interrogator 4, and after a certain period of time elapses, the response signals Al, A2. A3
Reply. At this time, each transponder 1. 2. 3 has exactly the same hardware and software configurations except for the identification number, so the three response signals AI and A2
．． A3 will also be sent out at exactly the same time. On the interrogator 4 side, three response signals Al, A2 . Since A3 overlaps, a normal received signal cannot be obtained. [0005] Therefore, in order to prevent multiple transponders from making reply operations at the same time, the 1
It is conceivable to add a response word designation function so that only a specific transponder responds to one question signal. However, in this method, it is necessary to send an interrogation signal specifying the transponder to all transponders, and it is necessary to send out interrogation signals for the number of transponders registered in advance. The problem is that it takes a very long time. [0006] The present invention has been made in view of the above points, and its purpose is to enable the interrogator to communicate efficiently even when a plurality of transponders exist within the interrogator's communication area. It is an object of the present invention to provide a communication method for a mobile object identification device that allows communication with all transponders within a possible area. [0007]

Means for Solving the Problems In the communication system of the mobile object identification device according to the present invention, as shown in FIG. 2, a transponder 1. 2. 3, and multiple transponders 1.3 at the same time. 2. It has a communicable area S that is large enough to include 1.3 transponders within the communicable area S. 2.
In the mobile object identification device, the interrogator 4 transmits an interrogation signal to the transponder 1.3 in a non-contact manner and receives a response signal in a non-contact manner.As shown in FIG. 2. After sending the interrogation signal Q to the transponders 1. 2.
A short timing signal Tl for sending a response signal from T2. ..., T7, and when the transponders 1, 2 and 3 receive the interrogation signal Q from the interrogator 4, they transmit their own response after receiving the timing signal a preset number of times. Signals Al, A2. A3
The device is characterized in that it is equipped with means for transmitting. [0008] Here, it is preferable that the interrogation signal or the timing signal include information that limits the transponder that should respond to the timing signal. [0009] Furthermore, the interrogator preferably includes means for changing the generation interval of the timing signal depending on the presence or absence of the response signal. [00101

[Operation] As shown in FIG. 1, after transmitting the interrogation signal Q, the interrogator 4 transmits a plurality of timing signals TI, T2 .・
・, T7 are transmitted sequentially. When the transponder 1 receives the first timing signal T1 after receiving the interrogation signal Q,
A response signal A1 is transmitted. When the transponder 2 receives the second timing signal T2 after receiving the interrogation signal Q,
A response signal A2 is transmitted. When the transponder 3 receives the fifth timing signal T5 after receiving the interrogation signal Q,
Transmit response signal A3. In this way, each transponder 1゜2
．． 3 receives different number of timing signals,
Response signals Al, A2 . If configured to transmit A3, response signals Al, A2 . No A3 interference will occur. [0011] Furthermore, when there is no response signal from the transponder, by generating the next timing signal, it is possible to have the transponders existing within the communicable area S return the response signal in a short time. [0012] Furthermore, if the interrogation signal or the timing signal includes information that limits the transponders that should respond to the timing signal, the number of timing signals can be made smaller than the number of transponders. [0013] Embodiment FIG. 1 shows the communication operation of an embodiment of the present invention. In the figure, Q is the interrogation signal of the interrogator 4, Al, A2 . A
3 is a transponder 1.3 existing within the communicable area S. 2.
3 response signals, Tl, T2. ..., T7 is a timing signal. Timing signals Tl, T2.
..., T7 may be any signal as long as it is shorter than the duration of the interrogation signal Q, and the signal may be of any type or form. [0014] FIG. 2 is a configuration diagram of a mobile object identification device to which the present invention is applied, in which three transponders 1. 2. 3 is present. However, in an actual system, it is assumed that the number of transponders that exist is larger, and that the number of transponders within the communicable area S increases or decreases. [00151 FIG. 4 is a block diagram showing a hardware configuration for realizing the present invention. In the figure, 4 is an interrogator, 2
is a transponder, Q is a question signal, and A is a response signal. In the interrogator 4, 10 is a data control/processing circuit;
12 is a modulator, 12 is a demodulator, 13 is a transmitting antenna, 14 is a receiving antenna, and 15 is a receiving amplifier. In the responder 2, 20 is a data control/processing circuit, 21 is a modulator, 2
2 is a demodulator, 23 is a transmitting antenna, 24 is a receiving antenna, and 25 is a receiving amplifier. [0016] The operation of this embodiment will be described below. The interrogator 4 transmits an interrogation signal Q in order to detect a transponder existing within the communicable area S. After that, timing signals Tl and T2 are used to indicate the response timing to the responder.
゜..., T7 is sent out as many times as necessary. The transponder 1 is set to send out a response signal including an identification number indicating its own existence when it receives a timing signal a specific number of times, and in FIG. 2 is set to 2 times, and responder 3 is set to 5 times. After transmitting the first timing signal T1, the interrogator 4 receives a response signal from the transponder, and in FIG. 1, the response signal A1 from the first transponder 1 is received. Therefore, by receiving this, the presence of the transponder 1 can be known. The same applies to the processing for the second timing signal T2. Next, since no response signal is received after sending out the third timing signal T3, the fourth timing signal T4 is sent out immediately. Fourth
The same applies to the processing for the timing signal T4. By performing such processing, it is possible to shorten the timing signal sending interval when no transponder is present, and even if the number of transponders increases and the number of timing signals to be sent increases, the timing signal transmission interval can be shortened. can be processed with. [0017] Here, if the number of times the transponder receives the timing signal is set to be different for each transponder, the response signals will not be transmitted at the same time, so the interrogator can reliably receive the response signal. Also, if there are a large number of transponders and it is difficult to set different reception times for all transponders,
The setting may be such that there are a plurality of transponders that transmit at the same time. Even in such a case, since there is a low probability that there are transponders that transmit response signals at the same timing within the communicable area S of the interrogator, processing is possible without the problem of signal collision. [00181 Next, the invention according to claim 2 will be explained. The invention according to claim 2 is characterized in that information that can limit the transponder that should respond to the interrogation signal is included. If the number of transponders becomes very large and all the transponders are set to transmit response signals at different timings, the processing time becomes long. invention becomes valid. Specifically, the information set in the transponder includes information indicating the transponder group in addition to the number of receptions of the above-mentioned timing signal, and when the transponder receives the interrogation signal,
A response signal is transmitted in response to reception of a set number of timing signals only when the own group information and the group information specified by the inquiry signal match. In this way, the interrogator can transmit an interrogation signal only to the group to be detected, and interference of response signals from the transponder will not occur, allowing efficient processing. [0019] In the invention according to claim 3, claim 2
In the described invention, the group information contained in the interrogation signal Q is transferred to the timing signals Tl, T2. ..., and in this case, the individual timing signals T1. T2. . . ., it is possible to limit the groups of responders, so that -layer efficient processing becomes possible.

[0020]

As described in detail above, according to the invention set forth in claim 1, the plurality of transponders existing within the communicable area of the interrogator each receive a predetermined number of times after receiving one interrogation signal. Since the response signal is returned after receiving the timing signal of There is an effect that the presence of all the transponders existing in the area can be detected by one interrogation signal. By including information that limits the transponders that should respond in the interrogation signal or timing signal, even if there are many transponders within the communicable area, only a limited number of transponders will respond. [0022]Furthermore, according to the invention set forth in claim 4, the interrogator includes means for changing the generation interval of the timing signal depending on the presence or absence of the response signal. Therefore, when there is a response signal, the timing signal generation interval can be lengthened, and when there is no response signal, the timing signal generation interval can be shortened, and when the timing signal generation interval is fixed. This has the advantage that it is possible to communicate with transponders within the communication area in a shorter time compared to the conventional method.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a communication operation according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a mobile object identification device that is the object of the present invention.

FIG. 3 is an explanatory diagram showing a communication operation in a conventional example.

FIG. 4 is a block diagram showing a hardware configuration for realizing the present invention.

[Explanation of symbols]

1 First responder 2 Second responder 3 Third responder 4 Interrogator

Claims (4)

[Claims] Claim 1: A transponder attached to a moving body, and a communication area large enough to simultaneously include a plurality of transponders,
In a mobile object identification device comprising an interrogator that sends an interrogation signal to a transponder in a communicable area in a non-contact manner and receives a response signal in a non-contact manner, the interrogator sends an interrogation signal to the transponder. Later, the transponder is equipped with means for transmitting a timing signal with a short time width for transmitting a response signal from the transponder, and upon receiving the interrogation signal from the interrogator, the transponder transmits the timing signal a preset number of times. A communication method for a mobile object identification device, characterized in that it is provided with means for transmitting its own response signal after receiving it. 2. A communication system for a mobile object identification device according to claim 1, wherein the interrogation signal includes information that limits a transponder that should respond to the timing signal. 3. A communication system for a mobile object identification device according to claim 1, wherein the timing signal includes information that limits a transponder that should respond to the timing signal. 4. A communication system for a mobile object identification device according to claim 1, wherein the interrogator includes means for changing the generation interval of the timing signal depending on the presence or absence of a response signal.