JP2006039899A - Contactless ic tag - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a contactless IC tag that enables communication with an interrogator in all directions. <P>SOLUTION: The IC tag comprises: two dipole antennas 1, 2 arranged orthogonally with each other; two changeover switches 3, 4 for selecting the two dipole antennas; two power supply circuits 7, 8 for generating a power supply from the received carrier waves; a comparator 9 for comparing the output voltage values of the two power supply circuits; and a signal selector 10 for selecting one of the output signals of two input-output circuits. The adaptive selection of antennas is performed by eliminating a null point in the power radiation directivity of the contactless IC tag and further using the received power intensity of the two dipole antennas, thereby enabling communications with the interrogator in all directions. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a non-contact IC tag using electromagnetic waves as an information transmission medium.

As a conventional non-contact IC tag, there exist some which were described in patent document 1, for example. FIG. 3 is a configuration diagram of a conventional non-contact IC tag described in Patent Document 1. In FIG. In FIG. 3, reference numeral 100 denotes a spherical semiconductor body having a diameter of 1 mm, and multiple semiconductor circuits are formed on a spherical surface. The circuit includes a nonvolatile memory, an information transmission / reception circuit, a power supply circuit for generating an operating power supply from received power, and a coil for impedance matching between the antenna and the circuit. Reference numeral 101 denotes a matching coil, and two matching coils are provided corresponding to the left and right elements of the antenna. Reference numerals 201 and 202 denote pieces of antenna elements, which are mechanically attached to a sphere of the main body by soldering 203 to constitute one dipole antenna.
Japanese Unexamined Patent Publication No. 2000-222540 (FIG. 1)

  However, the conventional transmission / reception antenna configuration using a single dipole antenna cannot receive an electric field vector having a direction perpendicular to the length direction of the dipole antenna, that is, power arriving from the length direction of the dipole antenna. However, depending on the orientation of the non-contact IC tag with respect to the interrogator antenna, the communication distance becomes extremely short or communication is impossible.

  The present invention solves the above-described conventional problems, and an object thereof is to provide a non-contact IC tag capable of communicating with an interrogator in all directions.

  In order to solve the above-described conventional problems, a non-contact IC tag according to the present invention includes an insulating substrate, two dipole antennas formed orthogonally on the substrate, and the orthogonal 2 on the substrate. The basic configuration is that it includes an IC chip mounted at the center of the two dipole antennas and having at least two changeover switches for selecting the two dipole antennas.

  In addition to the basic configuration described above, the IC chip further includes two input / output circuits that perform signal waveform shaping, two power supply circuits that generate a power supply voltage from the received carrier wave, and values of the two power supply voltages. It includes a comparator for comparison, a signal selector for selecting one of the output signals of the two input / output circuits, a modulation / demodulation circuit, a control circuit, and a memory, and may be a single module.

  According to the contactless IC tag of the present invention, depending on the orientation of the contactless IC tag, the problem that the communication distance becomes extremely short or cannot be communicated at all is solved, and stable communication with the interrogator from all directions is achieved. Is possible.

  Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1)
FIG. 1 is a configuration diagram of an antenna for a non-contact IC tag according to Embodiment 1 of the present invention. In FIG. 1, reference numerals 1 and 2 denote dipole antennas, which are made of a conductor, for example, copper foil, and are arranged orthogonal to each other. Reference numeral 30 denotes an IC chip in which a power supply circuit, a modulation / demodulation circuit, a control circuit, a memory, and the like are made into a single module. The The IC chip can detect the reception levels of the dipole antenna 1 and the dipole antenna 2 and select and receive a dipole antenna having a high reception level. Reference numeral 40 denotes a substrate. A dipole antenna 1 and a dipole antenna 2 are formed on the main surface of the substrate, and an IC chip 30 is placed at the center thereof.

  According to this configuration, since the dipole antenna 1 and the dipole antenna 2 are arranged orthogonally, the dipole antenna 1 and the dipole antenna 2 can receive radio waves. In the dipole antenna 1, the reception sensitivity in the direction in which the dipole antenna extends is reduced, but the radio wave in that direction is in the direction in which the reception sensitivity of the dipole antenna 2 is at the highest level. The lower direction is the direction in which the reception sensitivity of the other dipole antenna is higher. Therefore, by selecting a dipole antenna having a high reception level from among the dipole antenna 1 and the dipole antenna 2, electric field vectors in all directions can be received, and communication from all directions is possible.

(Embodiment 2)
FIG. 2 is a configuration diagram of the non-contact IC tag according to the second embodiment of the present invention. In FIG. 2, reference numerals 1 and 2 denote dipole antennas, which are formed of a conductor, for example, copper foil, and are arranged orthogonal to each other. 3 and 4 are selector switches for selecting the dipole antennas 1 and 2, 5 and 6 are input / output circuits that perform waveform shaping of signals, 7 and 8 are power supply circuits that generate power from the received carrier wave, 9 is a power supply circuit 7, 8, a comparator for comparing output voltage values of 8, a signal selector for selecting one of the output signals of the input / output circuits 5 and 6, 11 a modulation / demodulation circuit, 12 a control circuit, and 13 a memory.

  The AC power obtained by the dipole antenna 1 and the dipole antenna 2 is rectified by the power supply circuit 7 and the power supply circuit 8 to obtain a DC voltage. The DC voltage is compared by the comparator 9 to obtain a switch control signal Sc1. By the switch control signal Sc1, the switch connected to the power supply circuit having a large output voltage value is kept ON, while the switch connected to the power supply circuit having a small output voltage value is turned OFF, and the signal selector 10 performs the same operation. A signal is selected. After the end of communication, both the switch 1 and the switch 2 are set to ON by the switch control signal Sc2 generated by the control circuit.

  In general, the dipole antenna 1 has a property that the receiving sensitivity in the extending direction is low and the receiving sensitivity in the direction perpendicular to the extending direction is high. The same applies to the dipole antenna 2. The level of AC power received by the dipole antenna 1 and the dipole antenna 2 is compared by the comparator 9, and a dipole antenna having a high reception level can be selected adaptively. Accordingly, it becomes possible to receive electric field vectors in all directions, receive electric power arriving from all directions, and perform communication from all directions stably.

  Since the present invention enables stable communication with an interrogator from all directions, it is useful when used for a non-contact IC tag.

Configuration diagram of antenna for contactless IC tag in embodiment 1 of the present invention Configuration diagram of a non-contact IC tag in Embodiment 2 of the present invention Configuration diagram of conventional contactless IC tags

Explanation of symbols

1, 2 Dipole antenna 3, 4 Switch 30 IC chip

Claims (2)

An insulating substrate;
Two dipole antennas formed orthogonally on the substrate;
A non-contact IC tag comprising: an IC chip mounted on a central portion of the two dipole antennas orthogonal to each other on the substrate and having at least two changeover switches for selecting the two dipole antennas. The IC chip further includes:
Two input / output circuits that perform signal waveform shaping, two power supply circuits that generate a power supply voltage from a received carrier wave, a comparator that compares the values of the two power supply voltages, and one of the output signals of the two input / output circuits 2. The contactless IC tag according to claim 1, comprising a signal selector to be selected, a modulation / demodulation circuit, a control circuit, and a memory, and is made into a single module.

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