JP2001188889A - ID tag - Google Patents

Abstract

(57) [Problem] To reduce disadvantages peculiar to a microwave system that an ID tag cannot be used due to consumption of a battery. SOLUTION: When a magnetic flux generated from a reader / writer 2 is received by a loop coil 7 as a start-up command, a start-up control circuit 5 permits power supply to an internal circuit 3 of a battery 6. As a result, the internal circuit 3 is activated and performs microwave data transmission with the reader / writer 2 via the transmitting / receiving antenna 4. Upon receiving a signal from the internal circuit 3 indicating that data transmission has been completed, the activation control circuit 5 stops supplying power to the battery 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an RF-ID (Radi
o Frequency IDentification) relates to an ID tag used in a system.

[0002]

2. Description of the Related Art An RF-ID system is a system for identifying a person or an object by transmitting data at a relatively short distance (several tens of cm to several meters) using a radio signal. An electronic tag is attached to a person or object to be identified, and reading or writing of ID information on the ID tag is performed by a reader / writer connected to a computer.

[0003] Such an RF-ID system has the advantages that it can be quickly identified without making an inquiry to a database or the like, and that it is possible to disperse information and flexibly cope with system expansion / change. Has recently been widely used in various fields. For example, in a company, an ID tag is attached to the body of an employee as an employee ID card. When passing through the gate, the reader / writer reads the ID information of the ID tag to identify each person. In the field of factory automation (FA), each type of product flowing on a production line is
To ensure automatic sorting by attaching D-tags, and in the transportation and transportation fields, attach ID tags to trucks, trains, etc., to ensure efficient shipment management and train operation management in warehouses. ing.

There are various data transmission systems between the ID tag and the reader / writer, and representative systems include a system called an electromagnetic induction system and a system called a microwave system. In the electromagnetic induction method, a signal current of about several hundred kHz is applied to an antenna provided in a reader / writer to generate a magnetic field, and an induction magnetic field is generated in a loop coil of an ID tag located opposite to the antenna. Is used for data transmission. On the other hand, in the microwave method, the ID tag has a built-in battery and the reader /
Not only the writer but also the ID tag is microwave (2.45G
Hz) can be output, and data is transmitted between the two by this microwave.

[0005]

The electromagnetic induction system is an ID
While the tag has the advantage of not requiring a battery,
It has a disadvantage that the response speed is slow (several hundred ms), whereas the microwave system has a fast response speed (several tens of m).
s), but has the disadvantage that the ID tag becomes unusable when the battery in the ID tag is exhausted.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is possible to minimize the disadvantages unique to the microwave system by suppressing the battery consumption of the ID tag used in the microwave system. It is intended to provide a simple ID tag.

[0007]

According to a first aspect of the present invention, there is provided a reader / writer having an internal circuit using a battery as a power source and using a microwave as a radio signal. I that sends and receives data to and from
In a D tag, a start command receiving unit that receives an internal circuit start command from the reader / writer, and power supply of the battery to the internal circuit only when the internal circuit start command received by the start command receiving unit is input When the data transmission / reception operation of the internal circuit to the reader / writer is completed, the power supply from the battery is stopped to stop the operation of the internal circuit. And a control circuit.

According to a second aspect of the present invention, in the first aspect of the present invention, the internal circuit activation command is transmitted from the reader / writer using electromagnetic induction, and the activation command receiving unit is provided. Is formed by a loop coil capable of receiving a transmission signal using this electromagnetic induction.

[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 perspective view showing the internal configuration of the ID tag according to this embodiment. In this figure, at a position where an ID tag 1 and a reader / writer 2 face each other, data transmission between the two is performed using microwaves as a transmission medium.

The ID tag 1 has an internal circuit 3 formed by an IC. One end of the internal circuit 3 has a transmitting / receiving antenna 4 for transmitting / receiving to / from the reader / writer 2 by microwave. Is attached. In addition, one end of the activation control circuit 5 is arranged to face the other end of the internal circuit 3, and both are connected in this state. A battery 6 is arranged beside the activation control circuit 5, and the activation control circuit 5 can supply power from the battery 6 to the internal circuit 3. A loop coil 7 as a start command receiving unit is attached to the other end of the start control circuit 5. The internal circuit 3, the transmitting / receiving antenna 4, the start-up control circuit 5, the battery 6, and the loop coil 7 are formed of a case 8 made of a mold resin.
Is housed inside.

On the other hand, the reader / writer 2 has a function of transmitting microwaves to the ID tag 1 and a function of receiving microwaves from the ID tag 1.
It has a function of generating a magnetic field from the built-in antenna (not shown) to the ID tag 1 side. The generated magnetic field causes a magnetic flux to pass through the inside of the loop coil 7 in the ID tag 1 to generate an induced magnetic field. Therefore, a signal based on the induced magnetic field is sent to the activation control circuit 5 as an activation command from the reader / writer 2. Is to be entered. That is, the ID tag 1 and the reader / writer 2 in FIG.
Data transmission is performed between each other by the microwave system. The configuration of the electromagnetic induction system is partially adopted, and a start command (kick signal) for starting the start control circuit 5 is transmitted from the reader / writer 2 to the ID. It can be transmitted to the tag 1 side.

FIG. 2 is a diagram illustrating the concept of the operation of FIG. The activation control circuit 5 has a circuit 9 acting as an AND circuit, and a set terminal 10 and a reset terminal 11. An output from the battery 6 is input to one input terminal of the AND circuit 9, and a signal from the set terminal 10 or the reset terminal 11 is input to the other input terminal. When the condition is satisfied, the electric power from the battery 6 is output to the internal circuit (IC) 3 via the AND circuit 9.

What is input to the set terminal 10 is the above-mentioned start command sent from the reader / writer 2 to the loop coil 7. When this start command is input to the set terminal 10, the set terminal 10 Keeps outputting this start command to the other input terminal of the AND circuit 9. Therefore, while the start command is being input to the other input terminal, the AND circuit 9 outputs the power from the battery 6 input to the one input terminal to the internal circuit 3. The internal circuit 3 can perform microwave data transmission with the reader / writer 2 by supplying power from the battery 6. When the data transmission with the reader / writer 2 ends, the internal circuit 3 sends an OFF command to the reset terminal 11 meaning that the operation of the internal circuit 3 ends and the power supply from the battery 6 may be stopped. Output. When the reset terminal 11 inputs the off command, the output of the start command from the set terminal 10 to the other input terminal of the AND circuit 9 is stopped. As a result, the AND condition of the AND circuit 9 is not satisfied, so that the power supply from the battery 6 to the internal circuit 3 is stopped.

According to such an operation, power is supplied to the internal circuit 3 of the battery 6 only while the internal circuit 3 actually performs a data transmission operation.
Since the power supply operation of the battery 6 can be minimized, the power supply possible period of the battery 6 to the internal circuit 3 can be greatly extended. That is, in the conventional microwave type ID tag, power is always supplied from the battery 6 to the internal circuit 3 irrespective of whether data transmission is actually performed with the reader / writer. However, according to the above-described configuration, it is possible to reduce a disadvantage peculiar to the microwave system that the ID tag cannot be used due to the consumption of the battery. it can.

FIG. 3 is a flowchart for explaining a specific operation of the activation control circuit 5 in FIGS. 1 and 2. The activation control circuit 5 always determines whether or not the loop coil 7 as the activation instruction receiving unit is in a state of receiving an activation instruction from the reader / writer 2 (step 1). The reader / writer 2 constantly generates a magnetic field from a built-in antenna. When the ID tag 1 approaches the reader / writer 2 within a certain distance, the magnetic flux passes inside the loop coil 7.

Accordingly, the loop coil 7 is in a state of receiving the start command, and the determination in step 1 is "YES". As a result, A of the AND circuit 9 of the activation control circuit 5
The ND condition is satisfied, and the activation control circuit 5 permits the output of the battery 6 to the internal circuit 3 (step 2). Then, the internal circuit 3 that has been supplied with power from the battery 6 starts up, and performs microwave data transmission with the reader / writer 2 via the transmitting / receiving antenna 4. The data transmission distance by the microwave is longer than the data transmission distance by the magnetic field, and the satisfaction of the AND condition of the AND circuit 9 is maintained until the OFF command is input. Therefore, after the loop coil 7 once inputs the start command,
Even if the position of the ID tag 1 moves slightly and the loop coil 7 changes to a state in which the start command is not input, the internal circuit 3
Of the battery 6 from the battery 6 is continued.

The start control circuit 5 always determines whether or not an off command has been input from the internal circuit 3 (step 3), but the internal circuit 3 has completed data transmission with the reader / writer 2. When this is detected, an off command is output.
Accordingly, the determination in step 3 becomes “YES”, and A
Since the AND condition of the ND circuit 9 is not satisfied, the activation control circuit 5 stops the power supply of the battery 6 to the internal circuit 3 (step 4). Then, thereafter, the process returns to step 1 and the operations of steps 1 to 4 are repeated.

In the above-described embodiment, the loop command 7 of the reader / writer 2 receives the start command signal due to the magnetic field from the reader / writer 2. However, the signal from the sensor provided on the reader / writer 2 side is used. May be received by the sensor on the ID tag 1 side. For example, a light emitting element may be provided on the reader / writer 2 side, and a light receiving element may be provided on the ID tag 1 side, and the light receiving element may receive an optical signal from the light emitting element as a start command signal.

[0019]

As described above, according to the present invention, only when the start command receiving unit receives the internal circuit start command received, the power supply of the battery to the internal circuit is permitted and the internal circuit is started. With the reader /
When the data transmission / reception operation to the writer is completed,
Since the operation of the internal circuit is stopped by stopping the power supply from the battery, the power supply operation of the battery can be minimized and the ID tag cannot be used due to the consumption of the battery. The disadvantages peculiar to the microwave method can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the internal configuration of an ID tag according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating the concept of the operation in FIG. 1;

FIG. 3 is a flowchart for explaining a specific operation of the activation control circuit 5 in FIGS. 1 and 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ID tag 2 Reader / writer 3 Internal circuit 4 Transmission / reception antenna 5 Start-up control circuit 6 Battery 7 Loop coil (start-up command receiving part) 8 Case 9 AND circuit 10 Set terminal 11 Reset terminal

Claims (2)

[Claims] An ID tag having an internal circuit using a battery as a power source and transmitting / receiving data to / from a reader / writer using microwaves as a radio signal, wherein the internal circuit is activated from the reader / writer. A start command receiving unit that receives a command, and only when the start command receiving unit receives the internal circuit start command received, allows the power supply of the battery to the internal circuit and starts the internal circuit, When a data transmission / reception operation of the internal circuit with respect to the reader / writer is completed, a start control circuit for stopping power supply from the battery to stop the operation of the internal circuit, an ID tag comprising: . 2. The internal circuit activation instruction is transmitted from the reader / writer using electromagnetic induction, and the activation instruction receiving unit can receive a transmission signal using the electromagnetic induction. The ID tag according to claim 1, wherein the ID tag is formed by a loop coil.