JPH06169267A - Mobile body identification device - Google Patents

Abstract

PURPOSE:To avoid a communication disable state by revising transmission power of an interrogator based on a reception power detected by a reception power detection means and the result of detection by a reception error detection means. CONSTITUTION:A discrimination means 16 outputs a control signal to an attenuator 14 based on a detection signal from a reception power detection circuit 13 and a detection signal from a communication error detection means 15. The means 16 discriminates the occurrence of a communication error due to interference among plural responders B at a near interval when a communication error takes place and a reception level is high to decrease an output level of the interrogator A and to make the communication area narrow. When a communication error takes place and a reception level is low, since an interference error takes place among the plural responders B at a remote distance and it is not discriminated whether or not the power of the interrogator A is deficient, the result of error detection is monitored while the power of the interrogator A is increased. When the error takes place succeedingly, the power of the interrogator A is decreased and communication is started when the error is lost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a non-contact communication means such as a radio wave from an interrogator to assign the identification number of a transponder to a transponder that is held in a mobile unit and assigned a unique identification number. The present invention relates to a mobile body identification device that reads a response signal including the data and writes data to a transponder, and is particularly used in the FA field, physical distribution field, security field, and the like.

[0002]

2. Description of the Related Art Conventionally, in this type of moving body identifying apparatus, as shown in FIG. 4, an interrogator A includes a data control / processing circuit 1, a modulation circuit 2, a demodulation circuit 3, an amplification circuit 6, and a transmission antenna 4. , A receiving antenna 5, and the transponder B is
It has a reception antenna 7, a transmission antenna 8, an amplification circuit 9, a demodulation circuit 10, a modulation circuit 11, and a data control / processing circuit 12.

The interrogator A transmits an interrogation signal QS, and the transponder B, which has entered the communication area of the interrogator A, receives the interrogation signal QS and responds to the interrogation signal QS.
Is returned to the interrogator A.

[0004]

However, in the above-mentioned moving body identifying apparatus, normally, the communication area of the interrogator A is set to a constant value. For example, as shown in FIG.
When a plurality of transponders B1 to B3 enter the communication area S of one interrogator A, the plurality of transponders B1 to B3 simultaneously send back response signals to the interrogator A, resulting in an interference error. It happened and there was a problem that normal communication could not be done.

Therefore, if the communication area S of the interrogator A is reduced, the possibility that a plurality of responders B1 to B3 simultaneously enter the communication area S of one interrogator A is reduced, but the responders B1 to B3 are It may happen that you cannot communicate without entering the communication area. Conversely, the communication area S
When the value is increased, there is a high possibility that a plurality of responders B1 to B3 may enter the communication area S of the interrogator A at the same time.
There was a problem that interference error occurred and it became cheaper.

The present invention has been made in view of the above points, and it is an object of the present invention to avoid a communication impossible state due to an interference error of a plurality of transponders and to ensure reliable communication. To provide an identification device.

[0007]

DISCLOSURE OF THE INVENTION The present invention relates to a transponder which is held in a mobile body and is assigned a unique identification number, and a question which is transmitted to the transponder by using non-contact communication means such as radio waves. In the moving body identification device consisting of
A reception power detecting means for detecting the reception power and a communication error detecting means for detecting a communication error between the interrogator and the responder are added, and in the interrogator, based on the detection result of the reception power and the detection result of the communication error, It is characterized in that the transmission power is set.

[0008]

In the moving body identifying apparatus of the present invention, the magnitude of the transmission power of the interrogator is based on the magnitude of the reception power detected by the reception power detecting means and the detection result detected by the communication error detecting means. That is, the size of the communication area is set to an appropriate size.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic block diagram of a moving body identifying apparatus showing an embodiment of the present invention. Since the basic components of this embodiment are the same as those of the conventional moving body identifying apparatus described in FIG. 4, the same parts are designated by the same reference numerals and the description thereof will be omitted.

Reference numeral 13 is a received power detection circuit for detecting the magnitude of received power of the interrogator A, and is composed of, for example, an AGC circuit. In the reception power detection circuit 13, the reception antenna 5
The reply signal received from the responder B is received and the magnitude of the received power is sent to the data control / processing circuit 1.

Reference numeral 14 denotes an attenuator for adjusting the transmission power of the radio wave transmitted from the transmitting antenna 4, that is, for adjusting the size of the communication area of the interrogator A, which is a control signal from the data control / processing circuit 1. The attenuation amount is controlled by.

Reference numeral 15 is a communication error detecting means for detecting an error in the received data by, for example, a parity check or the like.

Reference numeral 16 is a judging means, which controls the attenuator 14 based on the detection signal from the reception power detecting circuit 13 and the detection signal from the communication error detecting means, that is, the magnitude of the reception power and the presence or absence of a communication error. It outputs a control signal for doing so. The judging method by the judging means 16 is
As shown in FIG. 2, when there is no communication error, the state at that time is maintained regardless of whether the received power level is high or low, and communication is continued with the communication area of the interrogator A as it is.
If a communication error occurs and the received power level is high,
When it is determined that a communication error due to the interference of a plurality of responders B occurs at a short distance, the output level of the interrogator A is lowered and the communication area is narrowed. If a communication error occurs and the received power level is low, it is not possible to determine whether there is an interference error due to a plurality of transponders B at a long distance or whether the output power of the interrogator A is insufficient. Monitor the error detection result while increasing the output power of. If the error continues to occur, it is determined that an interference error between the plurality of transponders B occurs at a long distance, and the output power of the interrogator A is reduced. If the error disappears at the point in time when there is an error, maintain the same condition and continue communication. In this embodiment, the communication error detecting means 15 and the judging means 16 are provided in the data control / processing circuit 1.

As described above, the interrogator A itself adjusts the communication area so that the plurality of transponders B are not present in the communication area of the interrogator A, and the occurrence of interference errors by the plurality of transponders B is prevented. It operates like.

Next, the operation of an example in which the moving body identifying apparatus of the present invention is applied to the sorting work of packages in the field of physical distribution will be described with reference to FIG. A1 is an interrogator, C1 and C2 are loads moving in the directions of arrows, and B1 and B2 are transponders attached to the loads C1 and C2. Interrogator A
1 is a transponder B1, B2 attached to the luggage C1, C2
Read the information about the parcels required for sorting work from
The obtained information is sent to a host computer (not shown), and the host computer performs sorting work according to the information.

Therefore, as shown in FIG. 3A, when the luggage C1 to which the responder B1 is attached is about to enter the communication area S1 of the interrogator A1, the interrogator A1 that is arbitrarily set is displayed. At the boundary of the communication area S1,
A communication error occurs between the interrogator A1 and the responder B1. Here, since the received power level of the interrogator A1 is low and a communication error has occurred, the output power of the interrogator A1 is increased within a predetermined value and the communication area S1 is expanded so as to prevent the occurrence of the communication error. Of. When the communication error disappears, the interrogator A1 continues the communication while maintaining the state.

Next, when the luggage C2 attached with the responder B2 tries to enter the communication area of the interrogator A1, the interrogator A1 is communicating with the responder B1, and the level of the received power of the interrogator A1 is Since the communication error is high and a communication error occurs, in order to prevent interference from the responder B2, as shown in FIG.
Is narrowed.

After that, as the luggage C1 gradually moves away from the interrogator A1, the communication area becomes wider, but the luggage C
When 2 approaches the interrogator A1, luggage C1 and luggage C2
If the distance from the interrogator A1 of 1 is reversed and the state shown in FIG. 3 (c) is reached, the responder B1 causes an interference error. Therefore, the communication area S3 should be narrowed and the interrogator A1
Communication with the transponder B2 is normally performed.

[0020]

As described above, according to the moving body identifying apparatus of the present invention, the interrogator is based on the magnitude of the received power detected by the received power detecting means and the detection result detected by the communication error detecting means. Since the size of the transmission power of, that is, the size of the communication area is set to an appropriate size,
A mobile body identification device capable of avoiding a communication impossible state due to an interference error of a plurality of transponders and enabling reliable communication can be provided.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram of an operation principle of the above.

FIG. 3 is a schematic diagram for explaining an operation of the above.

FIG. 4 is a block diagram according to a conventional example.

FIG. 5 is a schematic diagram for explaining an operation of the above.

[Explanation of symbols]

 A Interrogator B Responder 1 Data control / processing circuit 2 Modulation circuit 3 Demodulation circuit 4 Transmission antenna 5 Reception antenna 6 Amplification circuit 7 Reception antenna 8 Transmission antenna 9 Amplification circuit 10 Demodulation circuit 11 Modulation circuit 12 Data control / processing circuit 13 Reception Power detection circuit 14 Attenuator 15 Communication error detection means 16 Judgment means

Claims (1)

[Claims] 1. A mobile body identification device comprising a transponder held in a mobile body and assigned a unique identification number, and an interrogator for communicating with the transponder by using non-contact communication means such as radio waves. In the interrogator, a reception power detecting means for detecting the reception power and a communication error detecting means for detecting a communication error between the interrogator and the responder are added, and the interrogator detects the reception power and the communication error of the reception power. A mobile body identification device characterized in that transmission power is determined based on a detection result.