WO2005067159A1

WO2005067159A1 - Battery-less rf tag and interrogator

Info

Publication number: WO2005067159A1
Application number: PCT/JP2005/000041
Authority: WO
Inventors: Masao Nakagawa; Yukitoshi Sanada; Shinichiro Haruyama
Original assignee: Nakagawa Laboratories, Inc.
Priority date: 2004-01-07
Filing date: 2005-01-05
Publication date: 2005-07-21
Also published as: JP2005198032A

Abstract

[Problems] To provide a battery-less RF tag capable of acquiring information even from a long distance. [Means for solving problems] In structure (a), an interrogator (200) has a transmitting/receiving section (210) and a light-emitting section (220) for emitting a visible light having a sharp directivity. When a light having a sharp directivity such as a visible laser beam or an LED light beam is applied to a tag (300). A light-receiving section (320) of the tag (300) receives the light and converts the light into electric energy, and a transmitting/receiving section (310) of the tag (300) is operated by using the electric energy as the energy source. The radio wave sent from the interrogator (200) is modulated with information that the transmitting/receiving section (310) has and is sent to the interrogator as a radio wave. In structure (b), a tag (300) that has received a visible light from an interrogator (200) converts the light received at a light-receiving section (320) into electric energy. Using the power, a transmitting section (330) of the tag (300) generates a microwave, the microwave is modulated with data, and the modulated microwave is sent to the interrogator (200).

Description

Specification

No power supply RF tag and interrogator

Technical field

The present invention relates to a powerless RF tag and an interrogator.

Background art

[0002] Conventionally, tags using RF (radio frequency) have been used and used for identifying objects.

For example, if you attach an RF tag to a drug and try to obtain information about what kind of drug it is, the interrogator will emit a radio frequency radio wave at which the tag resonates toward the tag. The tag rectifies the radio wave to operate the electronic circuit in the tag, modulates the transmitted radio wave, and sends it back to the reader as a radio wave. FIG. 1 is a conceptual diagram showing the relationship between a conventional RF tag 120 and an interrogator 110. This is shown in Figure 1 with no power supply on the tag side.

A radio wave is emitted from the reader (interrogator) 110 as energy. In order to operate the RF tag 120, the non-powered RF tag 120 rectifies the radio wave from the interrogator 110 to generate power (power regeneration), modulates the radio wave sent from the interrogator 110, sends it back, and returns the tag. The information is transmitted to the reader (interrogator) 110. The reader (interrogator) 110 receives and demodulates the radio wave modulated by the RF tag to detect information.

For the above-mentioned conventional RF tag and interrogator, see Non-Patent Document 1, for example.

In the conventional system shown in FIG. 1, an important performance is how long the distance between the tag 120 and the interrogator 110 is. The longer the better, the better. The communication distance depends on the magnitude of the radio wave output of the interrogator 110 and the gain of the antennas 112 and 122 of the interrogator 110 and the RF tag 120. Normally, the force is several millimeters and several centimeters. It is said that the interrogator antenna can be made about 10 cm square at 2.4 GHz (the highest carrier frequency used for RF tags) to achieve a communication distance of about lm. Increasing the radio wave output to increase the distance will not be able to increase the license because it will cause interference with other tags and other communications. Therefore, an antenna 112 having a large gain is prepared for the interrogator 110. However, the antenna 112 having a large gain is also an antenna having a large shape. become. In addition, since the antenna 122 on the tag side cannot be made larger than the interrogator, gain cannot be gained on the tag side.

Thus, in the conventional RF tag, as the distance between the RF tag 120 and the reader (interrogator) 110 increases, the antenna 112 of the reader (interrogator) 110 increases, and the reader (interrogator) 110 Was an obstacle to miniaturization.

Non-Patent Document 1: Japan Automatic Recognition System Association, "RFIDs That We Understand" (Ohm Co., Ltd., September 10, 2003)

Disclosure of the invention

Problems to be solved by the invention

An object of the present invention is to make it possible to increase the distance from an interrogator in a non-power-supply RF tag.

Means for solving the problem

[0005] In order to achieve the object of the invention described above, the present invention relates to a light emitting unit that generates visible light with strong directivity for a non-powered RF tag, and information based on radio waves from the non-powered RF tag. An interrogator, comprising: a receiver that receives a visible light having the power of the interrogator and converts the light into electric energy; and an electric energy is supplied from the light receiver, and the interrogator is provided. And a transmitter for transmitting information by radio waves to the RF tag.

Further, the interrogator may be provided with a transmitter for transmitting a radio wave to the non-powered RF tag. The non-powered RF tag may be supplied with electric energy from the light receiving unit, and the interrogator may receive the electric energy from the interrogator. A transmitter for receiving radio waves is provided, and the transmitter modulates and transmits the received radio waves.

Further, the interrogator is provided with a positive periodic wave generator, and the light emitting unit is driven by the positive periodic wave generator. The light receiving unit of the non-power-supply RF tag has a filter and a rectifier circuit. The visible light that fluctuates at a specific cycle may be converted into electric energy.

The invention's effect

[0006] Since power is supplied to a non-power-supply tag using visible light, a power supply As compared with the case, the distance between the tag and the interrogator can be increased.

In addition, since only the target tag can be activated using the directivity of visible light, erroneous data is not obtained even when there are a plurality of tags.

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of the present invention will be described with reference to the drawings.

2 (a) and 2 (b) are views showing the configuration of the embodiment of the present invention.

In FIG. 2A, the interrogator 200 includes a transmitting / receiving unit 210 having the same configuration as that of the related art, and a light emitting unit 220 that generates visible light with sharp directivity. In this configuration, conventionally, an electromagnetic wave emitted from the interrogator 200 to the tag 300 for energy supply is radiated to the tag side as light having a sharp directivity of a visible laser or an LED. In the tag 300, the light is received by the light receiving unit 320 and converted into electric energy, and the transmission / reception unit 310 of the tag 300 is operated as an energy source. Then, the radio wave transmitted from the interrogator 200 is modulated by the information held in the transmission / reception unit 310 of the tag 300 and transmitted to the interrogator as a radio wave.

[0008] The configuration shown in FIG. 2 (b) is a slight modification of the configuration shown in FIG. 2 (a). In FIG. 2B, the tag 300 that has received the visible light from the interrogator 200 converts the light received by the light receiving unit 320 into electric energy. Utilizing the power, the transmitter 330 on the tag 300 generates a microphone mouth wave, modulates the data, and sends the modulated data to the interrogator 200. Although the load on the tag 300 will increase compared to the configuration shown in FIG. 2A, the load on the interrogator 200 will decrease.

[0009] The communication distance between the interrogator 200 and the tag 300 is determined by how much energy the tag 300 can receive as power. Using the radio wave from the interrogator 200, it modulates in a way such as reflection or non-reflection and sends it back. The sharp directivity of the light allows the transmitted energy to be transmitted to the tag without any loss even at long distances, and can supply energy to the power supply.

[0010] When energy is supplied to the tag 300 by a laser or an LED, which is a light emitting unit of the interrogator 200, it is necessary to accurately illuminate the tag 300 with light from the interrogator 200. By using visible light, the user can visually check which tag 300 was selected. If it is off, energy will not be transferred and the tag will not work. If there are multiple tags around the interrogator, only the illuminated tag will respond. Sharp rays should select enough tags Can do. This indicates that there is little danger of multiple nearby tags responding like radio waves and causing interference. Furthermore, data other than the tag targeted by the interrogator in response to a plurality of tags is not erroneously recognized as that of the target tag. Furthermore, even if multiple data including the target tag appear, it is not necessary for the interrogator to select necessary data from among them.

FIG. 3 shows a case where a no-power tag 300 for transmitting power by light is attached to the spine of a book. Since the power is transmitted to the non-powered tag 300 by light having a high directivity, even if the tags are densely arranged, the medium power can be selected. Only the tag selected by illuminating will react; other tags will not. The information of the book can be selectively obtained by illuminating the powerless tag 300 attached to the spine of the book.

In the case of a conventional tag that supplies power by radio waves, surrounding tags also react. In addition, since radio waves do not have sufficient directional characteristics of the antenna, power cannot be transmitted over long distances. Alternatively, the only option is to increase the size of the interrogator antenna. If it is light, the directivity is strong and tags can be selected.

[0012] Regardless of the radio wave, sending visible light to the interrogator tag is the power that a small LD (semiconductor laser) or LED (Light Emission Diode) can obtain by far the sharpest directivity compared to a radio wave. . In particular, the directivity of the laser light source is strong. This indicates that much of the energy transmitted can be transmitted to the tag without loss. The loss is small even if the distance is long. Since it is difficult to obtain such directivity with radio waves, a long distance loses a lot of energy. If it is attempted to have directivity, the radio wave becomes a large antenna and hinders miniaturization, but LEDs and LEDs can be miniaturized despite sharp directivity. In the configuration shown in FIG. 2, the reason for sending back from the tag side not by light but by radio waves is that only information needs to be sent back, and energy need not be transmitted. The transmission of information is much easier than the transmission of energy. That is, a large antenna gain and a large size antenna are not required for the interrogator.

In the configuration where microwaves are generated on the tag side shown in Fig. 2 (b), the burden on the tag side increases, but since radio waves only transmit information and energy transmission is not required, Fig. 2 (a) and the antenna It is the same from the viewpoint of. Example 1

FIG. 4 is a diagram for specifically explaining the interrogator 200 and the tag 300 shown in FIG. 2 (a).

In FIG. 4, the interrogator 200 includes a light emitting unit 224 using visible laser or LED, an antenna 231, a microwave transceiver 232, and a data display unit 234. The DC power supply 222 supplies power to each part. Interrogator 200 has the same configuration as the conventional interrogator except that it has light emitting section 224.

The light receiving unit 322 of the solar cell in the tag 300 receives the light from the light emitting unit 224, converts the received light into electric energy, and supplies power in the tag. The antenna 31, the modulation unit 313, and the data unit 314 have the same configuration as a conventional non-power-supply RF tag.

In this configuration, when light for power transmission from the light emitting unit 224 of the interrogator 200 hits the light receiving unit 322 of the tag 300, power supply to the transmitting and receiving unit 310 (FIG. 2A) starts. Then, the radio wave from the microwave transceiver 232 of the interrogator 200 is received by the antenna 311 of the tag 300, and the radio wave is modulated by the data from the data unit 314 by the modulation unit 313, so that the data in the tag 300 is transmitted. It is transmitted from the antenna 311 to the interrogator 200. Interrogator 200 receives the radio wave from tag 300 by antenna 231, demodulates by microwave transceiver 232, and displays it on data display unit 234.

The transmission and reception between the interrogator 200 and the tag 300 are performed only between the interrogator 200 and the tag irradiated with the power for transmission from the light emitting unit 224 of the interrogator 200.

Example 2

FIG. 5 is a diagram showing another configuration example of the interrogator 200 and the tag 300 shown in FIG. 2 (a). The configuration shown in FIG. 5 is a configuration example of power transmission that is not affected by background light. The same components as those in FIG. 4 are denoted by the same reference numerals.

In FIG. 5, since the light emitting unit (visible laser or LED) 224 of the interrogator 200 is driven by the output of the positive periodic wave generating unit 223 (it fluctuates at a constant frequency or a pseudo random pattern), the power transmission is performed. The working light fluctuates at a constant frequency or a pseudo-random pattern. The light receiving section (solar cell) 322 of the tag 300, which has received the light for power transmission, is a matched filter having a pseudo random pattern or frequency of the positive periodic wave generating section 223. Alternatively, the power in the tag is supplied as a DC current by the rectifier circuit 326 after passing through the bandpass filter 324. Therefore, the tag 300 does not operate unless the laser light or the LED light, which is a periodic wave, from the interrogator 200 is received. Therefore, the operation of the tag 300 is not affected by the sun or lighting. Note that the number of cycles (frequency) that takes a positive value is not 50 Hz or 60 Hz for AC power supply, but a frequency that is not easily affected by lighting.

The band-pass filter is used for selecting a simple periodic wave such as a sine wave. Matched 'filters can be used to select more general periodic waves, such as pseudo-random patterns. Bandpass filters are a special type of matched filters.

Example 3

FIG. 6 is a diagram showing a configuration example of the interrogator 200 and the tag 300 shown in FIG. 2 (b). The configuration shown in FIG. 6 is similar to the configuration example of power transmission not affected by the background light shown in FIG. The same components as those in FIG. 5 are denoted by the same reference numerals.

In this configuration, when light for power transmission from the light emitting unit 224 of the interrogator 200 hits the light receiving unit 322 of the tag 300, power supply to the transmitting unit 330 (FIG. 2 (b)) starts. Then, the signal transmitted by the oscillation circuit 331 of the tag 300 is modulated by the modulation circuit 332 with the data signal from the data section 314, so that the information in the tag 300 is transmitted from the antenna 311 to the interrogator 200.

The interrogator 200 receives the radio wave from the tag 300 with the antenna 231, demodulates it with the microwave transceiver 232, and displays it on the data display unit 234.

Even in the configuration shown in FIG. 6, since the light emitting unit (visible laser or LED) 224 of the interrogator 200 is driven by the output of the positive periodic wave generating unit 223, the tag 300 that receives the light for power transmission is used. The light receiving section (solar cell) 322 passes through a band-pass filter or a matched filter 324 that passes through the number of cycles (frequency) of the positive periodic wave generating section 223 and a pseudo random pattern, and then receives a direct current through a rectifier circuit 326. Power is supplied inside the tag using current. Therefore, as in the configuration of FIG. 5, unless the interrogator 200 receives laser light or LED light of the number of cycles (frequency) in the interrogator 200, the tag 300 does not operate. Therefore, the operation of the tag 300 is not affected by the sun or lighting.

Note that the positive periodic wave generator 223, matched filter and bandpass filter 324 are used. However, the interrogator and tag in FIG. 2 (b) can be configured with the same configuration as in FIG. Brief Description of Drawings

FIG. 1 is a diagram showing a configuration of a conventional RF tag.

FIG. 2 is a diagram showing a configuration of an embodiment of the present invention.

FIG. 3 is a diagram showing an application example in which a tag is attached to a spine of a book.

[4] FIG. 4 is a diagram showing a specific example of an interrogator and a tag.

FIG. 5 is a diagram showing another specific example of an interrogator and a tag.

FIG. 6 is a diagram showing another specific example of an interrogator and a tag.

Claims

The scope of the claims

[1] a light-emitting unit that generates visible light with high directivity for a non-powered RF tag,

A receiver for receiving information by radio waves of the powerless RF tag power;

An interrogator characterized by comprising:

[2] The interrogator according to claim 1,

The interrogator further includes a transmitter for transmitting a radio wave to the non-powered RF tag.

[3] In the interrogator according to claim 1 or 2,

An interrogator further comprising a positive periodic wave generator, wherein the light emitting unit is driven by the positive periodic wave generator.

[4] a light-receiving unit that receives the visible light of the interrogator power and converts it into electrical energy

A transmitter supplied with electric energy from the light receiving unit and transmitting information by radio waves to the interrogator;

A powerless RF tag comprising:

[5] The powerless RF tag according to claim 4,

Further, a receiver is supplied with electric energy from the light receiving unit, and receives a radio wave from the interrogator,

A non-powered RF tag, wherein the transmitter modulates and transmits a received radio wave.

[6] According to the powerless RF tag according to claim 4 or 5,

The light receiving unit has a filter and a rectifier circuit,

A powerless RF tag that converts only visible light power that fluctuates in a specific cycle into electrical energy.