Signal response medium, signal response medium identification system, code detection system, signal response medium identification method, and code detection method

Abstract

The present invention includes: an input unit that receives input of a chirp signal in which the oscillation frequency changes with time in a predetermined frequency band; a signal processing unit that includes a parallel circuit in which a plurality of bandpass filters that selectively allow signals at different center frequencies in the frequency band to pass are connected in parallel, and that generates a plurality of response signals related to the different center frequencies when the chirp signal is input to the parallel circuit via the input unit; and an output unit that outputs the response signals.

Description

Signal responsive medium, signal responsive medium identification system, code detection system, signal responsive medium identification method, and code detection method

[0001] The present invention relates to a signal responsive medium, a signal responsive medium identification system, a code detection system, a signal responsive medium identification method, and a code detection method.

[0002] JP2972040B discloses a responder medium that receives a chirp signal and returns a response signal, in which a plurality of LC circuits are hung on a line through which the chirp signal flows, the number of LC circuits is set corresponding to the responder's identification code, and the resonant frequencies of the LC circuits are individually set, and the response signal is formed by selectively attenuating the resonant frequency range corresponding to the identification code in the frequency spectrum of the chirp signal to form a dip.

[0003] However, in JP2972040B, the response signal is generated by the chirp signal propagating through the line while being affected by the impedance of the LC circuit. Therefore, the amplitude of the response signal decreases as it propagates through the line, which reduces the S / N ratio and the detection accuracy of the response signal.

[0004] Therefore, one aspect of the present invention aims to improve the detection accuracy of a response signal.

[0005] According to one aspect of the present invention, there is provided a signal response medium including an input section to which an oscillation signal whose oscillation frequency changes over time in a predetermined frequency band is input, a circuit in which a plurality of band-pass filters are connected in parallel to selectively pass signals of different center frequencies in the frequency band, a signal processing section that generates a plurality of response signals having different center frequencies when the oscillation signal is input to the circuit via the input section, and an output section that outputs the response signals.

[0006] According to one aspect of the present invention, an oscillation signal is input simultaneously to all band-pass filters, and each band-pass filter selectively passes a different center frequency, generating a plurality of response signals that have passed through each band-pass filter at different times. Therefore, the response signal that has passed through one band-pass filter is generated without being affected by the other band-pass filters, and the response signals that have passed through each band-pass filter do not overlap in time, thereby suppressing degradation of the response signal in the frequency and time directions. Therefore, it is possible to suppress degradation of the S / N ratio of the response signal in the frequency and time directions.

[0007] FIG. 1 is a diagram showing a signal-responsive medium (card type) according to this embodiment, and the relationship between a chirp signal input to the signal-responsive medium and a response signal output by the signal-responsive medium. FIG. 2 is a circuit diagram of the signal-responsive medium. FIG. 3 is a diagram showing the relationship between the frequency band of the chirp signal and discrete frequencies associated with the identification number of the signal-responsive medium. FIG. 4 is a circuit diagram of a band-pass filter. FIG. 5 is a Bode plot of the band-pass filter shown in FIG. 3. FIG. 6 is a diagram showing the results of a frequency characteristic analysis of a response signal output from the signal-responsive medium. FIG. 7 is a diagram showing the results of a transient response analysis of a response signal when a chirp signal is input to the signal-responsive medium. FIG. 8 is a schematic diagram of an inductor constituting a band-pass filter configured using a distributed constant circuit. FIG. 9 is a schematic diagram of a capacitor constituting a band-pass filter configured using a distributed constant circuit. FIG. 10 is a schematic diagram of a resistor constituting a band-pass filter configured using a distributed constant circuit. FIG. 11 is a plan view of a signal response medium (card type) and a reader constituting the code reading system of the first embodiment, showing the state before the signal response medium is inserted into the reader. FIG. 12 is a plan view of a signal response medium (card type) and a reader constituting the code reading system of the first embodiment, showing the state after the signal response medium is inserted into the reader. FIG. 13 is a side view of the reader constituting the code reading system of the first embodiment. FIG. 14 is a block diagram of the code reading system of the first embodiment. FIG. 15 is a schematic diagram of a signal response medium (card type) and a reader constituting the code reading system of the second embodiment. FIG. 16 is a schematic diagram of the code reading system of the second embodiment, when the reader verifies the signal response medium (card). FIG. 17 is a block diagram of the code reading system of the second embodiment. FIG. 18 is a modified example of the reader constituting the code reading system of the second embodiment. FIG. 19 is a block diagram of a code reading system of a third embodiment. Fig. 20 is a schematic diagram of a reader constituting the code reading system of the third embodiment. Fig. 21 is a schematic diagram of a signal response medium (key holder type) constituting the code reading system of a modified example of the third embodiment. Fig. 22 is a schematic diagram of a reader constituting the code reading system of a modified example of the third embodiment. Fig. 23 is a schematic diagram of a wristband equipped with a signal response medium.Fig. 24 is a schematic diagram showing an example of a wristband equipped with a signal response medium wound in a roll. Fig. 25 is a schematic diagram showing a state of a tag equipped with a signal response medium before it is cut off. Fig. 26 is a schematic diagram showing a state of a tag equipped with a signal response medium after it has been cut off. Fig. 27 is a schematic diagram showing a state of a label-type signal response medium before it is peeled off from a backing. Fig. 28 is a schematic diagram showing a state of a label-type signal response medium after it has been peeled off from a backing.

[0008] The embodiments described below are not limited to the drawings described by the brief description of the drawings.

[0009] A first form of the present invention is a signal response medium including: an input section to which an oscillation signal whose oscillation frequency changes over time in a predetermined frequency band is input; a circuit in which a plurality of band-pass filters are connected in parallel to selectively pass signals of different center frequencies in the frequency band; a signal processing section that generates a plurality of response signals related to the different center frequencies when the oscillation signal is input to the circuit via the input section; and an output section that outputs the response signals.

[0010] According to the first aspect, an oscillation signal is input simultaneously to all band-pass filters, and each band-pass filter selectively passes different frequencies, generating multiple response signals that have passed through each band-pass filter at different times. Therefore, the response signal that has passed through one band-pass filter is generated without being affected by the other band-pass filters, and the response signals that have passed through each band-pass filter do not overlap in time, thereby suppressing degradation of the response signal in the frequency and time directions. Therefore, it is possible to suppress degradation of the S / N ratio of the response signal in the frequency and time directions.

[0011] A second aspect of the present invention is a signal responsive medium according to the first aspect, wherein one of a pair of ends that connects a plurality of the bandpass filters of the circuit in parallel is connected to the input section, and the other of the pair of ends is connected to the output section.

[0012] According to the second embodiment, the oscillation signal before passing through the signal processing section is not included in the response signal, so that a decrease in the S / N ratio of the response signal can be suppressed.

[0013] A third aspect of the present invention is the first or second aspect, wherein the oscillation signal is a chirp signal whose oscillation frequency is swept in the frequency band, and the signal processing unit is a signal response medium that generates the response signal from the chirp signal.

[0014] According to the third aspect, it is possible to easily generate a response signal using a plurality of band-pass filters.

[0015] A fourth form of the present invention is any one of the first to third forms, wherein the plurality of band-pass filters are resonant circuits having mutually different resonant frequencies, and are a signal response medium that selectively passes the response signal of the oscillation signal having the resonant frequency as its center frequency.

[0016] According to the fourth aspect, a band-pass filter with a high Q factor can be constructed, and even if the difference between the resonant frequencies of two band-pass filters with different resonant frequencies is set narrow, the response signals appearing from the two band-pass filters can be clearly distinguished in the frequency domain and the time domain. Furthermore, an anti-resonance state occurs in a parallel circuit of two band-pass filters with different resonant frequencies, and the anti-resonance frequency appears between the two resonant frequencies. This causes a dip related to the anti-resonance frequency to appear between the two response signals in the frequency domain, making it possible to more clearly separate the two response signals in the frequency and time domains.

[0017] A fifth form of the present invention is any one of the first to fourth forms, further including a voltage generation circuit that rectifies the oscillation signal or an AC signal different from the oscillation signal to generate a DC voltage, and the signal processing unit is a signal response medium that can generate the response signal based on the potential on the low-voltage side of the DC voltage of the voltage generation circuit.

[0018] According to the fifth aspect, a response signal can be generated stably even if the signal response medium is not configured to be grounded to the outside.

[0019] A sixth form of the present invention is any one of the first to fifth forms, further including a mounting portion on which the input portion, the signal processing portion, and the output portion are mounted, and the input portion and the output portion are signal response media including an antenna arranged on a main surface of the mounting portion.

[0020] According to the sixth aspect, a non-contact type signal response medium can be easily constructed.

[0021] A seventh form of the present invention is a signal response medium according to the sixth form, wherein the antenna includes a first receiving antenna constituting the input section and a first transmitting antenna constituting the output section, and the first receiving antenna and the first transmitting antenna are arranged at different positions from each other on the main surface of the mounting section.

[0022] According to the seventh aspect, it is possible to reduce interference between an oscillation signal and a response signal in a reader that transmits an oscillation signal to a signal response medium and receives a response signal from the signal response medium.

[0023] The eighth form of the present invention is the seventh form, in which, when the oscillation signal is transmitted as radio waves, the first receiving antenna is capable of receiving the radio waves and transmitting the oscillation signal to the signal processing unit, and the first transmitting antenna is a signal response medium capable of transmitting the response signal as the radio waves.

[0024] According to the eighth aspect, wireless communication using radio waves between the signal response medium and the reader can be performed with a simple configuration.

[0025] A ninth aspect of the present invention is the signal response medium of the eighth aspect, wherein the frequency band of the radio waves is the UHF band.

[0026] According to the ninth aspect, by using radio waves in the UHF band, it is possible to increase the communication distance and simultaneously read a plurality of signal response media.

[0027] A tenth form of the present invention is a signal responsive medium according to any one of the first to ninth forms, wherein the bandpass filter includes a series circuit in which an inductor, a capacitor, and a resistor are arranged in this order, and an open end of the inductor is connected to the input section, and a connection midpoint between the capacitor and the resistor is connected to the output section.

[0028] According to the tenth aspect, a bandpass filter can be constructed with a simple configuration.

[0029] An eleventh aspect of the present invention is the signal responsive medium of the tenth aspect, wherein the series circuit is a signal responsive medium formed of a lumped constant circuit and / or a distributed constant circuit.

[0030] According to the eleventh aspect, it is possible to increase the variety of the impedance elements constituting the series circuit. In particular, when the series circuit is constructed entirely using distributed constant circuits, the entire circuit can be made compact, thereby increasing the information density per unit area (DPS). Furthermore, a bandpass filter with a high Q value can be constructed even with distributed constant circuits, thereby increasing the information density per unit frequency (DPF).

[0031] A twelfth form of the present invention is a signal response medium according to the tenth or eleventh form, further comprising a mounting portion on which the input portion, the signal processing portion, and the output portion are mounted, wherein an input terminal constituting the input portion, an output terminal constituting the output portion, and a ground terminal connected to the open end of the resistor are arranged on the mounting portion, and the input terminal, the output terminal, and the ground terminal are arranged at different positions on the mounting portion.

[0032] According to the twelfth embodiment, the contact-type signal response medium 1 can be easily constructed.

[0033] A thirteenth aspect of the present invention is a signal response medium in the sixth or twelfth aspect, wherein the mounting portion has any one of a card shape, a label shape, a key holder (pendant) shape, and a wristband shape.

[0034] According to the thirteenth aspect, the range of application of the signal response medium can be set to a wide range.

[0035] A fourteenth form of the present invention is a signal responsive medium identification system that includes the signal responsive medium of any one of the first to thirteenth forms, in which a plurality of discrete frequencies different from each other are set in the frequency band and the center frequency is set to one of the discrete frequencies, so that an identification number of the signal responsive medium is set by a combination of signal components of each center frequency in the response signal, and the signal responsive medium identification system extracts information of the center frequency from the response signal and determines whether there is a correspondence between information of all of the discrete frequencies and information of the extracted center frequency, thereby identifying the identification number.

[0036] According to the fourteenth aspect, the identification number set in the signal response medium can be easily identified. In addition, by appropriately setting the number of discrete frequencies and the number of band-pass filters, an identification number with a large amount of information can be set.

[0037] A fifteenth aspect of the present invention is a signal responsive medium identification system according to the fourteenth aspect, which includes a reader that transmits the oscillation signal to the signal responsive medium, the signal responsive medium transmitting the response signal to the reader, and the reader receiving the response signal.

[0038] According to the fifteenth aspect, communication between the signal responsive medium and the reader can be carried out in a non-contact manner.

[0039] A 16th form of the present invention is a code detection system that includes the signal responsive medium of any one of the first to thirteenth forms, in which a plurality of discrete frequencies different from one another are set in the frequency band, and information on the presence or absence of a signal component of each discrete frequency in the response signal is one bit, and a code having the number of bits as the number of pieces of information is set to be an identification number of the signal responsive medium, the code detection system including: a transmitter that transmits the oscillation signal to the input unit; a receiver that receives the response signal transmitted from the output unit; and a converter that converts the response signal to the code, in which, in the signal responsive medium, the number of the bandpass filters is set corresponding to the number of signals of the discrete frequencies that correspond to the identification number, and the center frequencies of the bandpass filters are individually set to be the discrete frequencies that are different from one another, and the converter performs a Fourier transform on the response signal to extract information of the center frequencies, and converts the response signal into the code by determining whether or not there is a correspondence between the information of all the discrete frequencies and the information of the extracted center frequencies.

[0040] According to the sixteenth aspect, the identification number set in the signal response medium can be identified as a code. In addition, by appropriately setting the number of discrete frequencies and the number of band-pass filters, it is possible to set codes and identification numbers with a large amount of information.

[0041] A seventeenth form of the present invention is a code detection system including the signal responsive medium of any one of the first to thirteenth forms, wherein a plurality of discrete frequencies different from one another are set in the frequency band, information on the presence or absence of a signal component of each discrete frequency in the response signal is set as one bit, and a code having the number of bits of said information is set to be an identification number of the signal responsive medium, the code detection system comprising: a reader for contacting the signal responsive medium to transmit the oscillation signal to the signal responsive medium and to receive the response signal from the signal responsive medium; a transmitter in the reader, which is arranged at a position where it contacts the input terminal when the signal responsive medium contacts the reader, and which transmits the oscillation signal to the input terminal; and a contact electrically connected to the transmitter, which is arranged at a position where it contacts the ground terminal when the input terminal contacts the transmitter in the reader. a receiving unit in the reader that is positioned so that the ground terminal comes into contact with the output terminal when the ground terminal comes into contact with the ground unit and receives the response signal transmitted from the output terminal; and a converting unit that converts the response signal into the code, wherein in the signal response medium, the number of band-pass filters is set corresponding to the number of signals of the discrete frequencies corresponding to the identification number, and the center frequencies of the band-pass filters are individually set to be the discrete frequencies that are different from each other, and the signal processing unit is grounded via the ground unit so that it can generate the response signal from the oscillation signal, and the converting unit Fourier transforms the response signal to extract information of the center frequency, and converts the response signal into the code by determining whether or not there is a correspondence between all of the information of the discrete frequencies and the extracted information of the center frequency.

[0042] According to the seventeenth aspect, an identification number set in a signal response medium can be identified as a code. In addition, by appropriately setting the number of discrete frequencies and the number of band-pass filters, a code and identification number with a large amount of information can be set, and the code can be detected with high accuracy through communication via contact electrodes.

[0043] An 18th form of the present invention is a code detection system according to the 16th or 17th form, wherein the transmitting unit changes the frequency of the oscillation signal so as to sweep from the lowest frequency to the highest frequency in the frequency band, and the converting unit performs a Fourier transform on the response signal to extract the center frequency component, or identifies information on the center frequency of the response signal based on the timing of the response signal received by the receiving unit, and converts the response signal into the code by determining whether or not there is a correspondence between information on all the discrete frequencies and the extracted or identified information on the center frequency.

[0044] According to the eighteenth aspect, the number of response signals and the discrete frequencies of the response signals can be detected with high accuracy.

[0045] A nineteenth aspect of the present invention is a code detection system including the signal-responsive medium of the eighth or ninth aspect, wherein a plurality of discrete frequencies different from one another are set in the frequency band, information indicating the presence or absence of a signal component of each discrete frequency in the response signal is one bit, and a code having the number of bits of the information is set to be an identification number of the signal-responsive medium, the code detection system comprising: a reader facing a main surface of the signal-responsive medium and arranged in close proximity to the signal-responsive medium, for transmitting the oscillation signal to the signal-responsive medium and receiving the response signal from the signal-responsive medium; a signal generating unit that generates the oscillation signal; and a second transmitting antenna that is arranged in the reader at a position facing the first receiving antenna when the signal-responsive medium is arranged in close proximity to the reader, for transmitting the radio wave related to the oscillation signal to the first receiving antenna. and a second receiving antenna in the reader, the second receiving antenna being arranged at a position facing the first transmitting antenna when the first receiving antenna is arranged close to the second transmitting antenna and receiving the radio waves related to the response signal transmitted from the first transmitting antenna, and a conversion unit converting the response signal into the code, wherein in the signal response medium, the number of the band-pass filters is set corresponding to the number of signals of the discrete frequencies corresponding to the identification number, and the center frequencies of the band-pass filters are individually set to be the discrete frequencies different from each other, and the conversion unit Fourier transforms the response signal to extract information of the center frequency, and converts the response signal into the code by determining whether or not there is a correspondence between all of the information of the discrete frequencies and the extracted information of the center frequency.

[0046] According to the nineteenth aspect, an identification number set in a signal response medium can be identified as a code. In addition, by appropriately setting the number of discrete frequencies and the number of band-pass filters, a code and identification number with a large amount of information can be set, and the code can be detected via communication through electromagnetic waves.

[0047] A twentieth form of the present invention is the code detection system of the nineteenth form, wherein the mounting portion has a flat plate shape, the first receiving antenna is capable of receiving the oscillation signal from both main surfaces of the mounting portion, the first transmitting antenna is capable of transmitting the response signal from both main surfaces of the mounting portion, a plurality of the second transmitting antennas are connected in parallel to the signal generating portion, a plurality of the second receiving antennas are connected in parallel to the converting portion, the plurality of the second transmitting antennas and the plurality of the second receiving antennas are arranged such that one second transmitting antenna and one second receiving antenna are aligned with each other in a first direction and the second transmitting antennas and the second receiving antennas are aligned alternately in a second direction orthogonal to the first direction, and the distance between the second transmitting antenna and the second receiving antenna aligned in the first direction is the same as the distance between the first receiving antenna and the first transmitting antenna.

[0048] According to the 20th aspect, multiple possible arrangements of the reader and the signal response medium can be set when the reader transmits an oscillation signal to the signal response medium and the signal response medium transmits a response signal to the reader, making it easy to communicate between the reader and the signal response medium.

[0049] A 21st form of the present invention is a code detection system including the signal responsive medium of the 8th form or the 9th form, wherein a plurality of discrete frequencies different from each other are set in the frequency band, information on the presence or absence of a signal component of each discrete frequency in the response signal is one bit, and a code having the number of bits of the information is set to be an identification number of the signal responsive medium, the code detection system comprising: a reader facing a main surface of the signal responsive medium and arranged in close proximity to the signal responsive medium, for transmitting the oscillation signal to the signal responsive medium and receiving the response signal from the signal responsive medium; a signal generator that generates the oscillation signal; a first transmitting / receiving antenna in the reader, arranged in a position facing one of the first receiving antenna and the first transmitting antenna when the signal responsive medium is arranged in close proximity to the reader, the first transmitting / receiving antenna being capable of transmitting the radio wave related to the oscillation signal and receiving the radio wave related to the response signal; a second transmitting / receiving antenna capable of transmitting the radio waves and receiving the radio waves related to the response signal; a conversion unit that converts the response signal into the code; and a switching unit that executes switching control to alternate between a first connection state in which the signal generation unit is connected to the first transmitting / receiving antenna but insulated from the second transmitting / receiving antenna and the conversion unit is connected to the second transmitting / receiving antenna but insulated from the first transmitting / receiving antenna, and a second connection state in which the signal generation unit is connected to the second transmitting / receiving antenna but insulated from the first transmitting / receiving antenna and the conversion unit is connected to the first transmitting / receiving antenna but insulated from the second transmitting / receiving antenna, wherein in the signal response medium, the number of the band-pass filters is set corresponding to the number of signals of the discrete frequencies corresponding to the identification number, and the center frequencies of the band-pass filters are individually set to be the discrete frequencies different from each other, and the conversion unit performs a Fourier transform of the response signal to extract information of the center frequencies, and converts the response signal into the code by determining whether or not there is a correspondence between all of the information of the discrete frequencies and the extracted information of the center frequencies.

[0050] According to the twenty-first aspect, when the first transmitting / receiving antenna functions as a transmitting antenna, the second transmitting / receiving antenna functions as a receiving antenna, and when the first transmitting / receiving antenna functions as a receiving antenna, the second transmitting / receiving antenna functions as a transmitting antenna. Therefore, for example, even if communication between the signal response medium and the reader is disabled when the signal response medium is placed upside down and close to the reader, communication becomes possible after a predetermined time has elapsed, thereby reducing the operational burden on a user using the signal response medium.

[0051] A 22nd form of the present invention is a code detection system according to the 21st form, wherein the mounting portion has a flat plate shape, the first receiving antenna is capable of receiving the oscillation signal from both main surfaces of the mounting portion, the first transmitting antenna is capable of transmitting the response signal from both main surfaces of the mounting portion, and in the reader, multiple first transmitting / receiving antennas and multiple second transmitting / receiving antennas are arranged so that one of them surrounds the other.

[0052] According to the twenty-second aspect, when the first transmitting / receiving antenna functions as a transmitting antenna, the second transmitting / receiving antenna functions as a receiving antenna, and when the first transmitting / receiving antenna functions as a receiving antenna, the second transmitting / receiving antenna functions as a transmitting antenna. Therefore, for example, when the signal response medium is placed close to the reader with the front and back sides and orientation of the signal response medium in any state, even if communication between the signal response medium and the reader is impossible, communication becomes possible after a predetermined time has elapsed, thereby reducing the operational burden on the user using the signal response medium.

[0053] A 23rd form of the present invention is a signal-responsive medium identification method for a signal-responsive medium including an input section to which an oscillation signal whose oscillation frequency varies over time in a predetermined frequency band is input, a circuit in which a plurality of band-pass filters are connected in parallel and which selectively pass signals of different center frequencies in the frequency band, wherein the oscillation signal is input to the circuit via the input section to generate a plurality of response signals related to the different center frequencies, and an output section to output the response signals, in which a plurality of discrete frequencies of different frequencies are set in the frequency band and the center frequency is set to one of the discrete frequencies, thereby setting an identification number of the signal-responsive medium by a combination of signal components of the center frequencies in the response signal, and the signal-responsive medium identification method extracts information of the center frequency from the response signal and determines whether there is a correspondence between information of all of the discrete frequencies and the extracted information of the center frequency, thereby identifying the identification number.

[0054] According to the twenty-third aspect, the identification number set in the signal response medium can be easily identified. In addition, by appropriately setting the number of discrete frequencies and the number of band-pass filters, an identification number with a large amount of information can be set.

[0055] A 24th form of the present invention relates to a signal responsive medium including an input section to which an oscillation signal whose oscillation frequency varies over time in a predetermined frequency band is input, a circuit in which a plurality of band pass filters for selectively passing signals of mutually different center frequencies in said frequency band are connected in parallel, said signal processing section generating a plurality of response signals relating to said mutually different center frequencies by inputting said oscillation signal to said circuit via said input section, and an output section for outputting said response signals, wherein a plurality of discrete frequencies mutually different in frequency are set in said frequency band, and information on the presence or absence of a signal component of each discrete frequency in said response signal is one bit, and a code having the number of bits of said information as the number of bits is set to said identification number in said signal responsive medium A code detection method for detecting the code of the signal responsive medium when the number of band-pass filters is set corresponding to the number of corresponding discrete frequencies and the center frequencies of the band-pass filters are individually set to be different discrete frequencies from each other, the code detection method comprising: a transmitting step of transmitting the oscillation signal to the signal responsive medium; a receiving step of receiving the response signal transmitted from the signal responsive medium; and a converting step of converting the response signal into the code, wherein in the converting step, the response signal is Fourier transformed to extract information of the center frequency, and the code detection method converts the response signal into the code by determining whether or not there is a correspondence between information of all the discrete frequencies and the extracted information of the center frequency.

[0056] According to the twenty-fourth aspect, the identification number set in the signal response medium can be identified as a code. In addition, by appropriately setting the number of discrete frequencies and the number of band-pass filters, it is possible to set codes and identification numbers with a large amount of information.

[0057] A 25th form of the present invention is a 24th form in which, in the transmitting step, the frequency of the oscillation signal is changed so as to sweep from the lowest frequency to the highest frequency in the frequency band, and in the converting step, the response signal is subjected to a Fourier transform to extract information of the center frequency, or the information of the center frequency of the response signal is identified based on a timing of receiving the response signal, and the response signal is converted into the code by determining whether or not there is a correspondence between information of all the discrete frequencies and the extracted or identified information of the center frequency.

[0058] According to the twenty-fifth aspect, the number of response signals and the discrete frequencies of the response signals can be detected with high accuracy.

[0059] Hereinafter, embodiments will be described with reference to the drawings.

[0060] [Basic Configuration of Signal-Responsive Medium 1] Fig. 1 is a diagram showing the signal-responsive medium 1 of this embodiment and the relationship between a chirp signal input to the signal-responsive medium 1 and a response signal output from the signal-responsive medium 1. Fig. 2 is a circuit diagram of the signal-responsive medium 1.

[0061] 1, the signal response medium 1 has, for example, a card-shaped mounting section 15 (housing), and a first receiving antenna 112 and a first transmitting antenna 133 are disposed within the mounting section 15. Although not shown, a signal processing section 12 (FIG. 2) is also disposed within the mounting section 15. The first receiving antenna 112 and the first transmitting antenna 133 are capable of communication from both main surfaces of the mounting section 15 (surfaces forming the card-shaped outer shape of the mounting section 15).

[0062] In addition to the non-contact type signal response medium 1 shown in FIG. 1, the present invention also includes contact type signal response media 1 shown in FIGS. 11 and 12, which will be described later.

[0063] A chirp signal, which will be described later, is input to the first receiving antenna 112 .

[0064] The signal processing unit 12 (FIG. 2) passes the chirp signal input from the first receiving antenna 112 to generate a response signal, and outputs the response signal to the first transmitting antenna 133 .

[0065] The first transmitting antenna 133 outputs (transmits) the response signal to the outside.

[0066] As shown in FIG. 2, the signal processing unit 12 has a series circuit (BPF1) of an inductor L1, a capacitor C1, and a resistor R1, a series circuit (BPF2) of an inductor L2, a capacitor C2, and a resistor R2, and a series circuit (BPF3) of an inductor L3, a capacitor C3, and a resistor R3.

[0067] The open ends of inductor L1, inductor L2, and inductor L3 are connected in parallel and connected to input section 11 (first receiving antenna 112), and the connection midpoint between capacitor C1 and resistor R1, the connection midpoint between capacitor C2 and resistor R2, and the connection midpoint between capacitor C3 and resistor R3 are connected in parallel and connected to output section 13 (first transmitting antenna 133).

[0068] The open ends of the resistors R1, R2, and R3 are grounded.

[0069] In the bandpass filter (BPF1), the inductor L1 and the resistor R1 function as a lowpass filter, and the capacitor C1 and the resistor R1 function as a highpass filter, thereby forming a bandpass filter, and the same is true for the bandpass filters (BPF2, BPF3).

[0070] The signal processing unit 12 is a parallel circuit in which bandpass filters (BPF1, BPF2, BPF3) having different resonance frequencies are connected in parallel.

[0071] 3 is a diagram showing the relationship between the frequency band of a chirp signal and the discrete frequencies associated with the identification number of the signal-responsive medium 1. When considering a case in which the frequency (f(t)) of the chirp signal changes linearly with time, the frequency f(t) is as follows:

[0072] where f(t) is the instantaneous oscillation frequency, f Ｌ is the lower limit frequency (start frequency), and k is the frequency increase rate or chirp rate, as follows:

[0073] where f Ｈ is the upper limit frequency (final frequency) that is higher than the lower limit frequency, and T is f Ｌ From f Ｈ The time (period) required to sweep from √Hz to √Hz is given by:

[0074] where θ ０ is the initial phase (time t=0).

[0075] In this embodiment, the lower limit frequency (f Ｌ ) and upper limit frequency (f Ｈ ) is used as the input signal.

[0076] In this embodiment, as shown in FIG. 3, n discrete frequencies (f １ , f ２ , f ３ , ...f ｎ－１ , f ｎ ) is set. １ <f ２ <f ３ <...<f ｎ－１ <f ｎ However, the magnitude relationship between the number and frequency can be set arbitrarily. １ The lower limit frequency (f Ｌ ) and set it to f ｎ The upper limit frequency (f Ｈ ) may be set to

[0077] In this embodiment, the information on the presence or absence of a signal related to each discrete frequency is set as 1 bit, and a code with the number of bits (number of digits) of the information (n pieces) is set to represent the identification number of the signal response medium 1.

[0078] That is, the signal processing unit 12 of this embodiment has a parallel circuit in which bandpass filters (BPF1, BPF2, BPF3) having mutually different resonant frequencies are connected in parallel, and the resonant frequencies (center frequencies) of the bandpass filters are set to any of the mutually different discrete frequencies. Furthermore, in the signal processing unit 12 of this embodiment, the number of bandpass filters and the resonant frequencies (center frequencies) are set so as to become the identification number of the signal responsive medium 1 having the signal processing unit 12.

[0079] For example, the n-digit identification number (f ｎ , f ｎ－１ , ...f ３ , f ２ , f １ ) as [00...111] (f １ = f ２ = f ３ = 1, f ４ = f ５ =...f ｎ When f = 0 is set, the number of bandpass filters (BPF1, BPF2, BPF3) is set to three, and the resonant frequencies of the bandpass filters are set to different values. １ , f ２ , f ３ is set to

[0080] Therefore, when a chirp signal is input to the signal processing unit 12, the center frequency is f １ The signal component (response signal) with a center frequency of f ２ The signal component (response signal) with a center frequency of f ３ A signal component (response signal) such that:

[0081] Therefore, the reader 2 (see FIG. 14) described later, which receives the multiple response signals, １ From f ｎBy determining whether or not there is a signal component up to this point, a code (an identification number for the signal responsive medium 1) is generated and recorded, and related information associated with the code (such as the name of the item to which the signal responsive medium 1 is attached) can be read out and / or displayed. Therefore, for two signal responsive media 1 having different related information, the number of band-pass filters and their center frequencies (resonant frequencies) are set so that the number of multiple response signals or the center frequencies of the response signals are different from each other.

[0082] When generating a code from multiple response signals, the center frequency (discrete frequency) can be calculated by Fourier transforming each response signal. Since each response signal is transmitted at a different timing, the discrete frequency can be determined based on the timing of reception of each response signal by the reader 2 (see FIG. 11, etc.).

[0083] As described above, the signal response medium 1 does not include a conventional IC (Integrated Circuit) chip for RFID (Radio Frequency Identification), and the response signal (analog signal) includes identification information (identification number) of the signal response medium 1, and this is also true for the following embodiments.

[0084] [Band-pass Filter Characteristics] Fig. 4 is a circuit diagram of a band-pass filter. Fig. 5 is a Bode plot of the band-pass filter shown in Fig. 4. The inventors of the present application have studied the frequency response of band-pass filters (BPFs). The band-pass filter (BPF) shown in Fig. 4 is one of the band-pass filters (BPF1, BPF2, BPF3) shown in Fig. 2, and has a series circuit of an inductor L, a capacitor C, and a resistor R. The open end of the inductor L serves as the input side (vi) of a chirp signal, the open end of the resistor R is grounded, and the midpoint of connection between the capacitor C and the resistor R serves as the output side (vo) of a response signal.

[0085] The transfer function of the bandpass filter (BPF) is as follows:

[0086] When the inductor L is set to 20 nH, the capacitor C is set to 5 pF, and the resistor R is set to 5 Ω, the resonant frequency is (1 / 2π) (1 / LC) 1／２ was 503.3 [MHz], and the Bode diagram shown in FIG. 5 was obtained.

[0087] As shown in Figure 5, the phase also abruptly inverts at the resonance frequency (center frequency) where the gain peaks. The Q value, which indicates the sharpness of the gain centered on the resonance frequency, is 63.24, and the damping ratio ζ is also a good value of 0.079.

[0088] Therefore, it can be seen that for two response signals that are adjacent to each other in frequency but have different resonant frequencies (center frequencies), the two response signals can be well separated even if the above-mentioned Δf is set to center frequency / Q value = 503.3 / 63.24 = 7.96 [Hz].

[0089] [Response signal generated by signal-responsive medium 1] Fig. 6 is a diagram showing the results of a frequency characteristic analysis of the response signal output from the signal-responsive medium 1. Fig. 7 is a diagram showing the results of a transient response analysis of the response signal when a chirp signal is input to the signal-responsive medium 1.

[0090] The inventors of the present application performed a frequency characteristic analysis and a transient response analysis of the signal-responsive medium 1 (signal processing unit 12) shown in Fig. 1. As a chirp signal, a signal source that sweeps from 100 MHz to 1 GHz at T = 10 ms was used, and the signal was output as the following function with an amplitude of 3 V.

[0091] In Fig. 1, the following settings were made: inductor L1 = 41 [nH], capacitor C1 = 5.1 [pF], resistor R1 = 1 [Ω], inductor L2 = 39 [nH], capacitor C2 = 5.1 [pF], resistor R2 = 1 [Ω], inductor L3 = 37 [nH], capacitor C3 = 5.1 [pF], resistor R3 = 1 [Ω]. As a result, the resonant frequency (f １ ) is set to 348 [MHz], and the resonant frequency (f ２ ) is set to 357 [MHz], and the resonant frequency (f ３) was set to 366 [MHz], and Δf=9 [MHz].

[0092] As shown in FIG. 6 (frequency analysis results), the response signal output from the signal processing unit 12 is output from the band pass filter (BPF1) at the resonant frequency (f １ ) is a response signal (f １ ), and the resonant frequency (f ２ ) is a response signal (f ２ ), and the resonant frequency (f ３ ) is a response signal (f ３ ) can be seen to be separable.

[0093] Also, the response signal (f １ ) has a Q value of 89.66, and the response signal (f ２ ) has a Q value of 87.45, and the response signal (f ３ The Q value of the response signal (f １ ) has a half-width of 3.88 [MHz], and the response signal (f ２ ) has a half-width of 4.08 [MHz], and the response signal (f ３ ) was 4.29 [MHz]. Therefore, it is clear that the response signal can be separated even when Δf is set to about 4 [MHz].

[0094] Furthermore, the response signal (f １ ) and the response signal (f ２ ) during which the gain suddenly decreases １２ = 352 [MHz]) is generated, and a response signal (f ２ ) and the response signal (f ３ ) during which the gain suddenly decreases. ２３ = 362 [MHz]) is generated.

[0095] Dip (f １２ ) corresponds to the anti-resonance frequency of the parallel circuit of the band pass filter (BPF1) and the band pass filter (BPF2), and the dip (f ２３) corresponds to the anti-resonance frequency in the parallel circuit of the band pass filter (BPF2) and the band pass filter (BPF3).

[0096] The anti-resonance frequency of the parallel circuit of the band-pass filter (BPF1) and the band-pass filter (BPF3) overlaps with the resonant frequency of the band-pass filter (BPF2), and therefore does not appear as a dip in the frequency analysis results.

[0097] In this way, in two band-pass filters having resonant frequencies adjacent to each other in frequency, an anti-resonant frequency appears between the two different resonant frequencies. Therefore, a dip related to the anti-resonant frequency occurs between multiple response signals having different center frequencies. Therefore, it is considered that the two response signals can be clearly separated in the frequency domain even if Δf is set to a value lower than 4 MHz, for example.

[0098] In FIG. 7 (transient response analysis results), at time t １ is the frequency of the chirp signal f １ The time when ２ is the frequency of the chirp signal f ２ The time when ３ is the frequency of the chirp signal f ３ This is the time when １ and time t ２ and time t ２ and time t ３ The interval is 5 μs.

[0099] As shown in FIG. 7, the response signal (f １ ), response signal (f ２ ), and the response signal (f ３ ) can be clearly separated. １２ is the time when the parallel circuit of the band pass filter (BPF1) and the band pass filter (BPF2) enters an anti-resonance state, and time t ２３is the time when the parallel circuit of the bandpass filter (BPF2) and the bandpass filter (BPF3) enters an anti-resonance state, and at this time a dip occurs in the transient response analysis results. Therefore, a dip related to the anti-resonance frequency appears between the two response signals in the time domain as well, so the two response signals can be clearly separated in the time domain as well.

[0100] From the above results, it can be seen that a configuration in which bandpass filters are connected in parallel can adopt a hybrid method, i.e., a dual detection method, that can detect response signals in both the frequency domain and the time domain, and can contribute to improving the reliability of code identification.

[0101] [Number of Codes in Signal Processing Unit 12] When n discrete frequencies having the above-mentioned bandwidth of Δf are set and the number of band-pass filters connected in parallel is r, the number of codes (number of identification numbers) is ｎ C ｒ As a design example, Ｌ =200 [MHz], f Ｈ When Δf = 390 [MHz] and Δf = 10 [MHz], n = 20 discrete frequencies can be set. When there are five band pass filters, ２０ C ５ = 658,008 possible codes, which can be used as a code equivalent to 19 bits (523,288). Also, when there are 10 band pass filters, ２０ C １０ = 847,660,528 possible codes, which can be used as a code equivalent to 29 bits (536,870,912).

[0102] [Distributed Constant Circuit] Fig. 8 is a schematic diagram of an inductor constituting a band-pass filter configured by a distributed constant circuit. Fig. 9 is a schematic diagram of a capacitor constituting a band-pass filter configured by a distributed constant circuit. Fig. 10 is a schematic diagram of a resistor constituting a band-pass filter configured by a distributed constant circuit.

[0103] 8, the distributed constant circuit of inductor L has an insulating printed circuit board 32 with a thickness H laminated on a conductive ground plate 31, and a conductive (copper foil or the like) microstrip line 33 with a width W and a length L1 arranged on the printed circuit board 32. Note that the printed circuit board 32 is preferably made of, for example, FR4 (GE4F, a standard of the National Electrical Manufacturers Association (NEMA) and the American National Standards Institute (ANSI), and a JIS standard).

[0104] The inventors of the present application then input information on the width W, length L1, height H (= 1.6 mm) of the printed circuit board 32, and dielectric constant ε (= 4.3) of the printed circuit board 32 into a microstrip inductance model (EMI Software: https: / / www.emisoftware.com / calculator / microstrip) to study the dimensions for an inductor L of 40 nH. As a result, W = 0.1 mm and L1 = 42 mm were obtained.

[0105] As shown in FIG. 9, the distributed constant circuit of the capacitor C is formed by arranging a first microstrip line 34 having a width W1 and a second microstrip line 35 having a width W2 on a printed circuit board 32 similar to that described above, facing each other with a gap of width s between them.

[0106] The inventors then input information on H (= 1.6 mm), W1, W2, and s into a microstrip gap model (Stefan John: https: / / qucs.sourceforge.net / tech / node79.html) to study the dimensions for a capacitor C of 5.1 pF. As a result, they obtained W1 = 0.1 mm, W2 = 0.2 mm, and s = 0.43 mm.

[0107] 10, the distributed constant circuit of resistor R can be expressed as a conductive rectangular parallelepiped 36 having a length L2 and a cross-sectional area S. When copper (Cu) (resistivity ρ=1.72 [Ω·cm]) is used as the material of resistor R, in order for the resistance R to be 1 [Ω], L2=0.12 [mm] and S=0.02 [cm] ２ ] (a rectangular shape of 2 [mm] x 1 [mm]) is required.

[0108] Here, when a series circuit of an inductor L, a capacitor C, and a resistor R is formed, the longitudinal dimension is slightly longer than L1+s+L2 (for example, 55 mm), and the lateral dimension occupies a rectangular area equal to the cross-sectional area S of the resistor R (2 mm). The area occupied by one bandpass filter is 0.55 × 0.2 = 0.09 cm ２ ]

[0109] As an evaluation criterion for a medium such as the signal response medium of this embodiment, the information density per unit area (DPS: Density per Surface [bit / cm 2 ]), or information density per unit frequency (DPF: Density per Frequency [bit / GHz]).

[0110] When the bandpass filter of the present invention is formed as a distributed constant circuit as described above, the occupied area per bandpass filter is 0.09 cm ２ ], so for example, five bandpass filters are estimated to be 2 [cm ２ Therefore, the area of ​​the five bandpass filters can be reduced to 2 [cm ２ ], then DPS = 3.1 x 10 ３ [bit / cm 2 ], DPF = 3.1 × 10 ６ On the other hand, in conventional media, DPS = 26 [bit / cm 2 ], DPF = 25 [bit / GHz], and the present invention achieves a DPS of 10 ２ times, 10 times with DPF ５ There is a performance difference of 2 times.

[0111] Let's consider a bandpass filter constructed using a lumped constant circuit. In this case, the inductor (40 nH) has a length of 1.0 mm, a width of 0.5 mm, and a depth of 0.5 mm (e.g., manufactured by Murata Manufacturing Co., Ltd., https: / / www.murata.com / ja-jp / products / productdetail?partno=LQW15AN40NG00%23). The capacitor (5 pF) has a diameter of 5 mm, a lead spacing of 5 mm, and a thickness of 3.5 mm (e.g., manufactured by SuperTech Electronic Co., Ltd., https: / / www.supertech.com.tw / products_detail / 70.htm). For a resistor (1 Ω), the length of the body is 9 mm and the diameter is 3.2 mm (for example, manufactured by Faithful link Industrial Corp., http: / / www.faithfullink-ind.com / pro.php?f=5&cid=8). Therefore, when forming a series circuit of LCRs, the inductor (longitudinal direction) and capacitor (diameter direction) are connected, and the lead extending from the capacitor is bent 180 degrees to connect the resistor. Therefore, the area occupied by one bandpass filter (LCR circuit) is 0.9 cm × (0.35 cm + 0.32 cm) = 0.6 cm ２ Therefore, if we consider the area of ​​the five bandpass filters in the same way as above, the area is 3 [cm ２ ], but in this case DPS = 2.1 x 10 ３ [bit / cm 2 ], DPF = 2.1 × 10 ６ From the above, even when the bandpass filter of the present invention is constructed using a lumped constant circuit, the DPS is 0.67 × 10 ２ times, DPF 0.67 x 10 ５ There is a performance difference of 2 times.

[0112] [Code reading system of the first embodiment] Fig. 11 is a plan view of a signal response medium 1 (card type) and a reader 2 that constitute the code reading system of the first embodiment, showing the state before the signal response medium 1 is inserted into the reader 2. Fig. 12 is a plan view of the signal response medium 1 (card type) and a reader 2 that constitute the code reading system of the first embodiment, showing the state after the signal response medium 1 is inserted into the reader 2. Fig. 13 is a side view of the reader 2 that constitutes the code reading system of the first embodiment. Fig. 14 is a block diagram of the code reading system of the first embodiment.

[0113] As shown in FIG. 11, the code reading system of the first embodiment is composed of a signal responsive medium 1 and a reader 2, and is an electrode contact type code reading system.

[0114] The signal response medium 1 may be a card type (credit card, SIM card) (Figs. 11 and 12) or a key type. The reader 2 may be a slide type or an insert type (Figs. 11 and 12).

[0115] 11 and 12, the signal response medium 1 has a card-shaped mounting section 15 on which an input terminal 111, a signal processing section 12, and an output terminal 131 are arranged, and the input terminal 111, the ground terminal 121, and the output terminal 131 are arranged at different positions on the main surface (the surface forming the card-shaped outer shape) of the mounting section 15. Note that the signal processing section 12 is omitted in FIGS.

[0116] As shown in Fig. 13, the reader 2 has a socket 204 for inserting the signal response medium 1. On the side wall (bottom) of the socket 204, there are arranged a first contact electrode 201 which constitutes the transmitting unit 21 (Fig. 14) and is used to transmit a chirp signal, a second contact electrode 202 which is electrically connected to the transmitting unit 21 (Fig. 14) and is grounded, and a third contact electrode 203 which constitutes the receiving unit 22 (Fig. 14) and is used to receive a response signal.

[0117] As shown in FIG. 13, the first contact electrode 201, the second contact electrode 202, and the third contact electrode 203 are arranged so as to protrude slightly from the side wall (bottom surface) of the socket 204.

[0118] The first contact electrode 201 is disposed at a position where it comes into contact with the input terminal 111 when the signal response medium 1 is inserted into the socket 204 .

[0119] The second contact electrode 202 is disposed at a position where it comes into contact with the ground terminal 121 when the signal-responsive medium 1 is inserted into the socket 204 .

[0120] The third contact electrode 203 is disposed at a position where it comes into contact with the output terminal 131 when the signal response medium 1 is inserted into the socket 204 .

[0121] As shown in Figure 12, when the signal response medium 1 is inserted into the socket 204 of the reader 2, the first contact electrode 201 contacts the input terminal 111, the second contact electrode 202 contacts the ground terminal 121, and the third contact electrode 203 contacts the output terminal 131, thereby enabling communication between the signal response medium 1 and the reader 2.

[0122] As shown in Figure 14, the signal response medium 1 includes a signal processing unit 12, an input unit 11 (input terminal 111) that receives a chirp signal and inputs the chirp signal to the signal processing unit 12, an output unit 13 (output terminal 131) that outputs multiple response signals generated by the signal processing unit 12, and a ground terminal 121 to which the open ends of resistors R1, R2, and R3 (Figure 2) that form the signal processing unit 12 are connected in parallel.

[0123] The reader 2 includes a transmitting unit 21 connected to the input terminal 111 and the ground terminal 121 and transmitting a chirp signal, a receiving unit 22 connected to the output terminal 131 and receiving a response signal, a converting unit 23 that converts the response signal into a code (an identification number of the signal response medium 1), a memory unit 25 in which related information associated with the code is stored, a reading unit 24 that reads out the related information in the memory unit 25 using the code generated by the converting unit 23, and a display unit 26 that displays the related information read out by the reading unit 24.

[0124] In the reader 2, at least the transmitting section 21 is grounded, so that the ground terminal 121 is grounded via the transmitting section 21, enabling the signal processing section 12 to generate a response signal.

[0125] The converter 23 performs a Fourier transform on the multiple response signals transmitted from the receiver 22 to extract (generate) center frequency information, and generates a code by determining whether or not all of the discrete frequency information corresponds to the extracted center frequencies. The converter 23 can also identify (generate) center frequency information of each response signal based on the timing of the sweep (oscillation frequency) of the chirp signal transmitted by the transmitter 21 and the timing of peaks appearing in the response signals received by the receiver 22, and generate a code by determining whether or not all of the discrete frequency information corresponds to the extracted or identified center frequency information. Thus, the converter 23 can identify the number of response signals and the center frequencies of each response signal in the frequency domain and / or the time domain.

[0126] The memory unit 25 stores related information associated with the code (such as information about the item to which the signal response medium 1 is attached), but when a code is input from the reading unit 24, it can also store the code in association with information about the time the code was input.

[0127] The display unit 26 is a display attached to the reader 2 and displays information related to the code generated by the conversion unit 23 .

[0128] In addition, the reading unit 24 and the memory unit 25 may be placed in an external device (not shown) separate from the reader 2, and the code information may be transmitted from the reader 2 (conversion unit 23) and related information may be transmitted from the external device (not shown) to the reader 2 (display unit 26).

[0129] [Code reading system of second embodiment] Fig. 15 is a schematic diagram of a signal response medium 1 (card type) and a reader 2 constituting a code reading system of the second embodiment. Fig. 16 is a schematic diagram of the code reading system of the second embodiment when the reader 2 collates the signal response medium 1. Fig. 17 is a block diagram of the code reading system of the second embodiment.

[0130] As shown in FIG. 15, the code reading system of the second embodiment is composed of a signal response medium 1 and a reader 2, similar to the first embodiment, but is a non-contact code reading system.

[0131] The signal response medium 1 may be, for example, a card type including an NFC (Near Field Communication) card (Figures 15 and 16), but other forms may also be used, such as a key holder type (Figure 21), a wristband type (Figures 23 and 24), a tag type (Figures 25 and 26), or a label type (Figures 27 and 28).

[0132] Furthermore, as the reader 2, for example, one having a shape with an upper surface (a surface that forms the outer shape when the reader 2 is viewed in a plane) facing the signal response medium 1 (Figures 15, 16, 18, 19, and 22) is applied.

[0133] 15, the card-type signal response medium 1 has a mounting portion 15 that forms its outer shape. A first receiving antenna 112 and a first transmitting antenna 133 are arranged so as to face each other on both main surfaces of the mounting portion 15 (surfaces that form the outer shape when the mounting portion 15 is viewed in plan). The first receiving antenna 112 and the first transmitting antenna 133 are arranged at different positions on both main surfaces.

[0134] 15, a second transmitting antenna 213 and a second receiving antenna 221 are disposed adjacent to the top surface inside the reader 2 (housing). The second transmitting antenna 213 and the second receiving antenna 221 are disposed at different positions in a plan view, but the distance between the second transmitting antenna 213 (center) and the second receiving antenna 221 (center) is set to be the same as or approximately the same as the distance between the first receiving antenna 112 (center) and the first transmitting antenna 133 (center).

[0135] As shown in Figure 16, communication between the signal response medium 1 and the reader 2 becomes possible by holding the signal response medium 1 over (positioning the signal response medium 1 close to) the reader 2 so that the first receiving antenna 112 of the signal response medium 1 faces the second transmitting antenna 213 of the reader 2 and the first transmitting antenna 133 of the signal response medium 1 faces the second receiving antenna 221 of the reader 2.

[0136] As shown in Figure 17, the signal response medium 1 includes an input section 11 (first receiving antenna 112), a signal processing section 12, an output section 13 (first transmitting antenna 133), and a voltage generating circuit 14, which are housed in a mounting section 15 (Figures 15 and 16).

[0137] The reader 2 includes a transmitting unit 21 (signal generating unit 211, second transmitting antenna 213), a receiving unit 22 (second receiving antenna 221), a converting unit 23, a reading unit 24, a memory unit 25, and a display unit 26, which are arranged within the housing of the reader 2.

[0138] The signal generating unit 211, the converting unit 23, the reading unit 24, the storage unit 25, and the display unit 26 may be configured to be arranged in an external device (not shown) outside the reader 2 (housing).

[0139] In the reader 2, the signal generating unit 211 generates a chirp signal or an AC signal different from a chirp signal.

[0140] The second transmitting antenna 213 transmits a chirp signal or an AC signal different from a chirp signal as a radio wave toward the signal response medium 1 .

[0141] In the signal response medium 1, the first receiving antenna 112 outputs the chirp signal or an AC signal different from the chirp signal transmitted from the reader 2 as a radio wave to the signal processing unit 12.

[0142] The first transmitting antenna 133 transmits the response signal as a radio wave toward the reader 2 .

[0143] In the reader 2 , the second receiving antenna 221 outputs the response signal returned as a radio wave from the first transmitting antenna 133 to the conversion unit 23 .

[0144] In the signal-responsive medium 1 , the voltage generating circuit 14 is connected in parallel with the signal processing unit 12 to the input unit 11 .

[0145] The voltage generating circuit 14 is a rectifier circuit that converts AC voltage into DC voltage, and is configured by connecting a capacitor to a bridge circuit formed by multiple diodes. The low-voltage side of the capacitor that constitutes the voltage generating circuit 14 is connected to the open end of the resistor R that constitutes the signal processing unit 12.

[0146] The voltage generating circuit 14 rectifies the chirp signal received by the first receiving antenna 112 or an AC signal other than the chirp signal transmitted by the transmitter 21 (signal generating unit 211) and stores a charge in a capacitor. As a result, the signal processing unit 12 (resistors R1, R2, and R3, see FIG. 2) is grounded by the voltage generating circuit 14, so that a response signal to the chirp signal can be reliably generated.

[0147] In correspondence with the voltage generating circuit 14, the transmitting unit 21 (signal generating unit 211) can transmit the AC signal different from the chirp signal before transmitting the chirp signal. When a charge is stored in the capacitor of the voltage generating circuit 14 by the chirp signal, the lowest discrete frequency (f １ ) is the lower limit frequency of the chirp signal (f Ｌ ) and set the chirp signal to a lower limit frequency (f Ｌ ) to the upper limit frequency (f Ｈ ) when sweeping to the lower limit frequency (f Ｌ ) to discrete frequencies (f １ ) may be configured to store charge in the capacitor of the voltage generation circuit 14 using an AC signal of up to 100 kHz. The DC voltage generated by the voltage generation circuit 14 is supplied to a capacitor constituting the voltage generation circuit 14, and the capacitor smoothes the DC voltage to stabilize the level of the response signal.

[0148] For communication between the signal responsive medium 1 and the reader 2, a radio wave method (radiation electromagnetic field method) is applied, but a wide-band antenna is used to cover the frequency bandwidth of the chirp signal.

[0149] The frequency bands of the chirp signal (radio wave) are UHF band, VHF band, and microwave band.

[0150] Although not shown in the figure, the second transmitting antenna 213 and the second receiving antenna 221 included in the reader 2 are arranged so that their polarization directions are orthogonal to each other. Correspondingly, the first receiving antenna 112 and the first transmitting antenna 133 included in the signal response medium 1 are arranged so that their polarization directions (longitudinal directions of the members constituting the antennas) are orthogonal to each other. This makes it possible to reduce interference between the chirp signal and the response signal in the reader 2 (second receiving antenna 221). Note that each antenna can be, for example, a patch antenna that can have a wide bandwidth.

[0151] [Modification of Second Embodiment] Fig. 18 shows a modification of the reader 2 constituting the code reading system of the second embodiment. As shown in Fig. 18, when the directions are orthogonal to each other, the X direction, and the Y direction, second transmitting antennas 213 and second receiving antennas 221 are arranged alternately (in a staggered arrangement) in the X direction and the Y direction on the top surface of the reader 2.

[0152] In Figure 18, one second transmitting antenna 213 and one second receiving antenna 221 are arranged side by side in the X direction, and the second transmitting antennas 213 and second receiving antennas 221 are arranged alternately in the Y direction, but the second transmitting antennas 213 and second receiving antennas 221 may also be arranged alternately in the X direction.

[0153] It is preferable to arrange the second transmitting antenna 213 and the second receiving antenna 221 so that the spacing between them in the X and Y directions is the same (or approximately the same) as the spacing between the first receiving antenna 112 and the first transmitting antenna 133 of the signal response medium 1.

[0154] 18 , the Y direction is the longitudinal direction of the signal response medium 1 and the reader 2, and the first receiving antenna 112 and the first transmitting antenna 133 are aligned in the X direction (short direction) in the signal response medium 1. Therefore, it is preferable to arrange them so that at least the spacing in the X direction between the second transmitting antenna 213 (the center of the second transmitting antenna 213) and the second receiving antenna 221 (the center of the second receiving antenna 221) of the reader 2 is the same (or approximately the same) as the spacing between the first receiving antenna 112 and the first transmitting antenna 133 of the signal response medium 1.

[0155] Corresponding to the configuration shown in Figure 18, multiple second transmitting antennas 213 are connected in parallel to the signal generating unit 211 (Figure 17), and multiple second receiving antennas 221 are also connected in parallel to the converting unit 23 (Figure 17).

[0156] In the arrangement shown in Figure 18, when the first receiving antenna 112 of the signal response medium 1 is positioned opposite one of the second transmitting antennas 213 of the reader 2, communication becomes possible between the signal response medium 1 and the reader 2 when the first transmitting antenna 133 of the signal response medium 1 is positioned opposite the second receiving antenna 221 adjacent to the second transmitting antenna 213 of the reader 2.

[0157] [Code Reading System of Third Embodiment] Fig. 19 is a block diagram of a code reading system of a third embodiment. Fig. 20 is a schematic diagram of a reader 2 constituting the code reading system of the third embodiment.

[0158] In the code reading system of the third embodiment, the signal response medium 1 is the same as that of the second embodiment (FIGS. 15 and 16).

[0159] The reader 2 does not have the second transmitting antenna 213 dedicated to transmission and the second receiving antenna 221 dedicated to reception as in the second embodiment, but is provided with a first transmitting / receiving antenna 27A (Figures 19 and 20), a second transmitting / receiving antenna 27B (Figures 19 and 20), and a switching unit 28 (Figure 19).

[0160] As shown in Figure 19, the switching unit 28 alternately switches the connection state between a first connection state in which the signal generation unit 211 is connected to the first transmission / reception antenna 27A and insulated from the second transmission / reception antenna 27B, and the conversion unit 23 is connected to the second transmission / reception antenna 27B and insulated from the first transmission / reception antenna 27A, and a second connection state in which the signal generation unit 211 is connected to the second transmission / reception antenna 27B and insulated from the first transmission / reception antenna 27A, and the conversion unit 23 is connected to the first transmission / reception antenna 27A and insulated from the second transmission / reception antenna 27B, at a predetermined period (a period sufficiently longer than the sweep period T of the chirp signal).

[0161] Therefore, when the first transmission / reception antenna 27A functions as a transmission antenna, the second transmission / reception antenna 27B functions as a reception antenna, and when the first transmission / reception antenna 27A functions as a reception antenna, the second transmission / reception antenna 27B functions as a transmission antenna.

[0162] 20 , the first transmitting / receiving antenna 27A and the second transmitting / receiving antenna 27B are arranged in a staggered configuration on the top surface of the reader 2, as in the second embodiment. Note that in the third embodiment as well, it is preferable to arrange them so that the spacing between the first transmitting / receiving antenna 27A (the center of the first transmitting / receiving antenna 27A) and the second transmitting / receiving antenna 27B (the center of the second transmitting / receiving antenna 27B) of the reader 2 in at least the X direction is the same (or approximately the same) as the spacing between the first receiving antenna 112 and the first transmitting antenna 133 of the signal response medium 1.

[0163] In Figure 20, when the first receiving antenna 112 of the signal response medium 1 is placed in close proximity to a position facing one of the first transmitting / receiving antennas 27A, the first transmitting antenna 133 of the signal response medium 1 is placed in close proximity to a position facing one of the second transmitting / receiving antennas 27B adjacent to the first transmitting / receiving antenna 27A of the reader 2, and when the connection state of the switching unit 28 is in the first state, communication becomes possible between the signal response medium 1 and the reader 2.

[0164] Also, in Figure 20, when the first receiving antenna 112 of the signal response medium 1 is placed in close proximity to a position facing one of the second transmitting / receiving antennas 27B, the first transmitting antenna 133 of the signal response medium 1 is placed in close proximity to a position facing one of the first transmitting / receiving antennas 27A adjacent to the second transmitting / receiving antenna 27B of the reader 2, and when the connection state of the switching unit 28 is in the second state, communication becomes possible between the signal response medium 1 and the reader 2.

[0165] Therefore, in the third embodiment, even if the signal responsive medium 1 is turned over and placed facing the reader 2, communication between the signal responsive medium 1 and the reader 2 is possible.

[0166] [Code reading system according to a modification of the third embodiment] Fig. 21 is a schematic diagram of a signal response medium 1 (key holder type) constituting a code reading system according to a modification of the third embodiment. Fig. 22 is a schematic diagram of a reader 2 constituting a code reading system according to a modification of the third embodiment.

[0167] As shown in FIG. 21, the signal response medium 1 (mounting portion 15) is a key holder (pendant) type, but its function is the same as that of the signal response medium 1 (card type) of the second embodiment (FIG. 16).

[0168] The key holder (pendant) type signal responsive medium 1 (mounting portion 15) has a mounting portion 15 that forms its outer shape. The mounting portion 15 includes a circular central portion 151 and a frame portion 152 that has a shape that surrounds the outer periphery of the central portion 151 and that combines a shape that imitates a part (semicircle) of the outer shape of the central portion 151 with a tapered shape, and that has a through hole 1521 in the tapered portion. The signal responsive medium 1 also includes a first ring 153 that is inserted into the through hole 1521 and coupled to the frame portion 152, and a second ring 154 that is inserted into the first ring 153 and coupled to the first ring 153. The first receiving antenna 112 and the first transmitting antenna 133 are disposed, for example, inside the central portion 151.

[0169] 22 , for example, one first transmitting / receiving antenna 27A is disposed in the reader 2, and a plurality of second transmitting / receiving antennas 27B are disposed so as to surround the first transmitting / receiving antenna 27A. Note that, also in the modified example of the third embodiment, it is preferable to dispose the antennas so that at least the distance between the first transmitting / receiving antenna 27A (the center of the first transmitting / receiving antenna 27A) of the reader 2 and the second transmitting / receiving antenna 27B (the center of the second transmitting / receiving antenna 27B) disposed around the first transmitting / receiving antenna 27A is the same (or approximately the same) as the distance between the first receiving antenna 112 and the first transmitting antenna 133 of the signal response medium 1.

[0170] Here, with regard to the position and orientation of the signal response medium 1, when the first receiving antenna 112 of the signal response medium 1 is positioned opposite and close to the first transmitting / receiving antenna 27A of the reader 2, and the first transmitting antenna 133 of the signal response medium 1 is positioned opposite and close to one of the second transmitting / receiving antennas 27B of the reader 2, communication becomes possible between the signal response medium 1 and the reader 2 when the connection state of the switching unit 28 is in the first connection state.

[0171] Furthermore, with regard to the position and orientation of the signal response medium 1, when the first transmitting antenna 133 of the signal response medium 1 is positioned opposite and close to the first transmitting / receiving antenna 27A of the reader 2, and the first receiving antenna 112 of the signal response medium 1 is positioned opposite and close to one of the second transmitting / receiving antennas 27B of the reader 2, communication becomes possible between the signal response medium 1 and the reader 2 when the connection state of the switching unit 28 is the second connection state.

[0172] The code reading systems of the first to third embodiments function as a signal-responsive medium identification system in which a plurality of discrete frequencies different from one another are set in the frequency band of the chirp signal, and the identification number of the signal-responsive medium 1 is set by a combination of signal components of each center frequency in the response signal. The signal-responsive medium identification system extracts center frequency information from the response signal, and determines whether there is a correspondence between all of the discrete frequency information and the extracted center frequency information, thereby specifying the identification number of the signal-responsive medium 1.

[0173] Furthermore, with regard to the second and third embodiments, the signal response medium identification system further includes a reader 2 that is capable of transmitting an oscillation signal and receiving a response signal via a predetermined frequency band and that identifies the identification number.

[0174] [Wristband 4 Mounted with Signal Responsive Medium 1] Fig. 23 is a schematic diagram of a wristband 4 mounted with a signal responsive medium 1. Fig. 24 is a schematic diagram showing an example of a wristband 4 mounted with a signal responsive medium 1 wound in a roll.

[0175] 23, the wristband 4 includes a band part 41 for wrapping around the wrist, and a signal response medium 1 (mounting part 15) attached to the surface of the longitudinal end of the band part 41. The mounting part 15 is formed in a sheet shape using a material such as plastic, and is joined to the band part 41 with an adhesive (not shown).

[0176] An adhesive portion 411 is disposed on the reverse side of the end of the band portion 41 to which the signal response medium 1 is attached. A protective sheet (not shown) is attached to the surface of the adhesive portion 411. With the band portion 41 wrapped around the wrist, the protective sheet (not shown) is peeled off from the adhesive portion 411 and the exposed surface of the adhesive portion 411 is attached to a part of the surface of the band portion 41, forming the wristband 4 into a ring shape and worn on the wrist. The adhesive portion 411 can be attached to any position on the surface of the band portion 41, so the ring diameter can be adjusted as desired.

[0177] As shown in Figure 24, the base material of the wristband 4 is a continuous body S1 wound into a roll. The continuous body S1 has perforations M1 formed therein for separation that match the length of the band portion 41, and the signal response medium 1 (mounting portion 15) is attached adjacent to the perforations M1. Therefore, by cutting the continuous body S1 at the position of the perforations M1, the wristband 4 can be cut out from the continuous body S1.

[0178] [Tag 5 Mounted with Signal Response Medium 1] Fig. 25 is a schematic diagram showing the state of the tag 5 mounted with the signal response medium 1 before it is cut off. Fig. 26 is a schematic diagram showing the state of the tag 5 mounted with the signal response medium 1 after it has been cut off.

[0179] 24 and 25, the tag 5 includes a mount 51 and a sheet-like signal response medium 1 (mounting section 15) attached to the surface of the mount 51. The mounting section 15 is made of plastic or the like, similar to that used in the wristband 4, but is formed in the shape of a freely deformable sheet.

[0180] The base material of the tag 5 is a continuum S2, which has perforations M2 formed to match the length of the backing 51. A sheet-like signal response medium 1 (mounting portion 15) is attached to the continuum S2 at a position between a pair of adjacent perforations M2. The continuum S2 is wound into a roll with the signal response medium 1 attached.

[0181] As shown in FIG. 25, for example, one tag 5 can be cut out by cutting the continuous body S2 at a perforation M2 at the end of the continuous body S2.

[0182] [Label-type signal response medium 1] Fig. 27 is a schematic diagram showing the state of the label-type signal response medium 1 before it is peeled off from the backing paper 52. Fig. 28 is a schematic diagram showing the state of the label-type signal response medium 1 after it has been peeled off from the backing paper 52.

[0183] 27, the signal-responsive medium 1 (mounting portion 15) is a label formed in a sheet shape. The mounting portion 15 may be similar to that used in the tag 5 described above, but has an adhesive (not shown) applied to its back surface. The signal-responsive medium 1 is attached to a backing sheet 52 with the adhesive (not shown). The backing sheet 52 is wound into a roll with the signal-responsive medium 1 attached, similar to the continuum S2.

[0184] As shown in Figure 28, the signal response medium 1 can be removed from the backing paper 52 by directly peeling it off, and the label-type signal response medium 1 can be directly attached to the object using an adhesive (not shown).

[0185] [Effects of this embodiment] The signal responsive medium 1 of this embodiment includes an input unit 11 to which an oscillation signal (chirp signal) whose oscillation frequency changes over time in a predetermined frequency band is input, and a circuit (parallel circuit) in which a plurality of bandpass filters (BPF1, BPF2, BPF3) that selectively pass signals of different center frequencies in the frequency band are connected in parallel, a signal processing unit 12 that generates a plurality of response signals having different center frequencies when the oscillation signal (chirp signal) is input to the circuit (parallel circuit) via the input unit 11, and an output unit 13 that outputs the response signals.

[0186] With the above configuration, an oscillation signal is input simultaneously to all band-pass filters (BPF1, BPF2, BPF3), and each band-pass filter selectively passes different frequencies, generating multiple response signals that have passed through each band-pass filter at different times. Therefore, the response signal that has passed through one band-pass filter is generated without being affected by the other band-pass filters, and the response signals that have passed through each band-pass filter do not overlap in time, thereby suppressing degradation of the response signal in the frequency and time directions. Therefore, it is possible to suppress degradation of the S / N ratio of the response signal in the frequency and time directions.

[0187] In this embodiment, one of a pair of ends that connects multiple bandpass filters (BPF1, BPF2, BPF3) in parallel in the circuit (parallel circuit) is connected to the input unit 11, and the other of the pair of ends is connected to the output unit 13.

[0188] With the above configuration, the oscillation signal (chirp signal) before passing through the signal processing unit 12 is not included in the response signal, so that a decrease in the S / N ratio of the response signal can be suppressed.

[0189] In this embodiment, the oscillation signal (chirp signal) is a chirp signal whose oscillation frequency is swept in a frequency band, and the signal processing unit 12 generates a response signal from the chirp signal.

[0190] With the above configuration, it is possible to easily generate a response signal using a plurality of band-pass filters (BPF1, BPF2, BPF3).

[0191] In this embodiment, the plurality of band-pass filters (BPF1, BPF2, BPF3) have mutually different resonant frequencies (f １ , f ２ , f ３ ) and selectively passes a response signal having a center frequency at the resonant frequency among the oscillation signals (chirp signals).

[0192] The above configuration makes it possible to construct a bandpass filter with a high Q value, and even if the difference (Δf) between the resonant frequencies of two bandpass filters with different resonant frequencies is set narrow, the response signals appearing from the two bandpass filters can be clearly distinguished in the frequency domain and the time domain. Furthermore, an anti-resonance state occurs in a parallel circuit of two bandpass filters with different resonant frequencies, and the anti-resonance frequency appears between the two resonant frequencies. This causes a dip related to the anti-resonance frequency to appear between the two response signals in the frequency domain, making it possible to more clearly separate the two response signals in the frequency and time domains.

[0193] In this embodiment, the signal processing unit 12 further includes a voltage generation circuit 14 that rectifies an oscillation signal (chirp signal) or an AC signal different from the oscillation signal (chirp signal) to generate a DC voltage, and the signal processing unit 12 is capable of generating a response signal based on the DC voltage of the voltage generation circuit 14.

[0194] With the above configuration, a response signal can be generated stably even if the signal response medium 1 is not configured to be grounded to the outside.

[0195] In this embodiment, the device further includes a mounting portion 15 on which the input portion 11, the signal processing portion 12, and the output portion 13 are mounted, and the input portion 11 and the output portion 13 include antennas (first receiving antenna 112, first transmitting antenna 133) arranged on the main surface of the mounting portion 15.

[0196] With the above configuration, the non-contact type signal response medium 1 can be easily constructed.

[0197] In this embodiment, the antenna includes a first receiving antenna 112 that constitutes the input section 11 and a first transmitting antenna 133 that constitutes the output section 13, and the first receiving antenna 112 and the first transmitting antenna 133 are arranged at different positions on the main surface of the mounting section 15.

[0198] With the above configuration, interference between the oscillation signal (chirp signal) and the response signal in the reader 2 that transmits the oscillation signal (chirp signal) to the signal-responsive medium 1 and receives the response signal from the signal-responsive medium 1 can be reduced.

[0199] In this embodiment, when the oscillation signal is transmitted as radio waves, the first receiving antenna 112 can receive the radio waves and transmit the oscillation signal to the signal processing unit 12, and the first transmitting antenna 133 can transmit a response signal as radio waves.

[0200] With the above-described configuration, wireless communication using radio waves between the signal response medium 1 and the reader 2 can be performed with a simple configuration.

[0201] In this embodiment, the frequency band of the radio waves is the UHF band.

[0202] With the above configuration, by applying radio waves in the UHF band, it is possible to extend the communication distance and read a plurality of signal response media 1 at once.

[0203] In this embodiment, the bandpass filter includes a series circuit in which an inductor L, a capacitor C, and a resistor R are arranged in this order, and the open end of the inductor L is connected to the input section 11, and the midpoint of connection between the capacitor C and the resistor R is connected to the output section 13.

[0204] With the above configuration, a bandpass filter can be constructed with a simple configuration.

[0205] In this embodiment, the series circuit is composed of a lumped constant circuit and / or a distributed constant circuit.

[0206] The above configuration allows for greater versatility in the creation of each impedance element (inductor L, capacitor C, resistor R) that makes up the series circuit. In particular, when the series circuit is constructed entirely using distributed constant circuits, the entire circuit can be made compact, thereby increasing the information density per unit area (DPS). Furthermore, a bandpass filter with a high Q value can be constructed using distributed constant circuits, thereby increasing the information density per unit frequency (DPF).

[0207] In this embodiment, the device further includes a mounting portion 15 on which the input section 11 (input terminal 111), signal processing section 12, and output section 13 (output terminal 131) are mounted, and the mounting portion 15 is provided with the input terminal 111 constituting the input section 11, the output terminal 131 constituting the output section 13, and a ground terminal 121 connected to the open end of resistor R (of the bandpass filter), and the input terminal 111, output terminal 131, and ground terminal 121 are arranged at different positions on the mounting portion 15.

[0208] With the above configuration, the contact-type signal response medium 1 can be easily constructed.

[0209] In this embodiment, the mounting portion 15 has any one of a card shape, a label shape, a key holder (pendant) shape, and a wristband shape.

[0210] With the above configuration, the signal response medium 1 can be applied in a wide range.

[0211] The code detection system of this embodiment includes a signal-responsive medium 1, in which a plurality of discrete frequencies different from one another are set in a frequency band (of a chirp signal), and information on the presence or absence of a signal component of each discrete frequency in a response signal is set as one bit, and a code having the number of bits of this information is set to be the identification number of the signal-responsive medium 1. The code detection system includes a transmitter 21 that transmits an oscillation signal (chirp signal) to an input unit 11, a receiver 22 that receives the response signal transmitted from an output unit 13, and a converter 23 that converts the response signal into a code, and in the signal-responsive medium 1, the number of band-pass filters (BPF1, BPF2, BPF3) is set corresponding to the number of signals of the discrete frequencies corresponding to the identification number (of the signal-responsive medium 1), and the center frequencies (f １ , f ２ , f ３ ) are individually set to have mutually different discrete frequencies, and the conversion unit 23 performs a Fourier transform on the response signal to extract information on the center frequency, and converts the response signal into a code by determining whether or not there is a correspondence between the information on all the discrete frequencies and the extracted information on the center frequency.

[0212] With the above configuration, it is possible to identify as a code the identification number set on the signal response medium 1. Furthermore, by appropriately setting the number of discrete frequencies and the number of band-pass filters, it is possible to set codes and identification numbers with a large amount of information.

[0213] The signal-responsive medium identification system of the present invention includes a signal-responsive medium 1, and is a signal-responsive medium identification system in which a plurality of discrete frequencies different from each other are set in a frequency band (of a chirp signal), and the center frequency is set to one of the discrete frequencies, so that the identification number of the signal-responsive medium 1 is set by the combination of signal components of the center frequencies in the response signal.The system extracts center frequency information from the response signal, and determines whether there is a correspondence between the information of all the discrete frequencies and the extracted center frequency information, thereby identifying the identification number.

[0214] The above configuration makes it possible to easily identify the identification number set on the signal response medium 1. Furthermore, by appropriately setting the number of discrete frequencies and the number of band-pass filters, it is possible to set an identification number with a large amount of information.

[0215] In this embodiment, the signal responsive medium includes a reader 2 that transmits an oscillating signal to a signal responsive medium 1, which transmits a response signal to the reader 2, which receives the response signal.

[0216] With the above configuration, communication between the signal response medium 1 and the reader 2 can be carried out in a non-contact manner.

[0217] The code detection system according to this embodiment includes a (contact-type) signal-responsive medium 1, in which a plurality of discrete frequencies different from one another are set in a frequency band (of a chirp signal), and information indicating the presence or absence of a signal component of each discrete frequency in a response signal is set as one bit, and a code having the number of bits of this information is set as an identification number of the signal-responsive medium 1. The code detection system includes a reader 2 that contacts the signal-responsive medium 1 to transmit an oscillation signal (chirp signal) to the signal-responsive medium 1 and receives a response signal from the signal-responsive medium 1, a transmitter 21 (first contact electrode 201) in the reader 2 that is positioned so as to contact an input terminal 111 when the signal-responsive medium 1 contacts the reader 2, and that transmits the oscillation signal (chirp signal) to the input terminal 111, and a grounding section (second contact electrode 202) disposed in a position that contacts the ground terminal 121 when the input terminal 111 contacts the transmitting section 21 (first contact electrode 201) in the reader 2; a receiving section (third contact electrode 203) disposed in a position that contacts the output terminal 131 when the ground terminal 121 contacts the grounding section (second contact electrode 202) in the reader 2, and receiving a response signal transmitted from the output terminal 131; and a converting section 23 that converts the response signal into a code; and in the signal responsive medium 1, the number of band pass filters (BPF1, BPF2, BPF3) is set in accordance with the number of signals of discrete frequencies corresponding to the identification number (of the signal responsive medium 1), and the center frequencies (f １ , f ２ , f ３ ) are individually set to have mutually different discrete frequencies, and the conversion unit 23 performs a Fourier transform on the response signal to extract information on the center frequency, and converts the response signal into a code by determining whether or not there is a correspondence between the information on all the discrete frequencies and the extracted information on the center frequency.

[0218] With the above configuration, it is possible to identify as a code the identification number set in the signal response medium 1. Furthermore, by appropriately setting the number of discrete frequencies and the number of band-pass filters, it is possible to set a code and identification number with a large amount of information, and the code can be detected with high accuracy through communication via the contact electrodes.

[0219] In this embodiment, the transmitter 21 transmits the lowest frequency (lower limit frequency (f Ｌ ) to the highest frequency (upper limit frequency (f Ｈ )), and the conversion unit 23 performs a Fourier transform on the response signal to extract information about the center frequency, or identifies information about the center frequency of the response signal based on the timing of the response signal received by the receiving unit 22, and converts the response signal into a code by determining whether or not there is a correspondence between information about all the discrete frequencies and the extracted or identified information about the center frequency.

[0220] With the above configuration, the number of response signals and the discrete frequencies of the response signals can be detected with high accuracy.

[0221] The code detection system of this embodiment includes a (contactless) signal-responsive medium 1, in which a plurality of discrete frequencies different from one another are set in a frequency band (of a chirp signal), and information indicating the presence or absence of a signal component of each discrete frequency in a response signal is set as one bit, and a code having the number of bits as the number of pieces of information is set as an identification number of the signal-responsive medium 1. The code detection system includes a reader 2 that is disposed adjacent to the signal-responsive medium 1 while facing the main surface of the signal-responsive medium 1 and that transmits an oscillation signal (chirp signal) to the signal-responsive medium 1 and receives a response signal from the signal-responsive medium 1, a signal generating unit 211 that generates the oscillation signal (chirp signal), and a first receiving antenna in the reader 2 when the signal-responsive medium 1 is disposed adjacent to the reader 2. a second transmitting antenna 213 disposed in a position opposite the first transmitting antenna 133 when the first receiving antenna 112 is disposed close to the second transmitting antenna 213 in the reader 2, a second receiving antenna 221 disposed in a position opposite the first transmitting antenna 133 when the first receiving antenna 112 is disposed close to the second transmitting antenna 213, and receiving the radio wave related to the response signal transmitted from the first transmitting antenna 133; and a conversion unit 23 that converts the response signal into a code, and in the signal responsive medium 1, the number of band pass filters (BPF1, BPF2, BPF3) is set in accordance with the number of signals of discrete frequencies corresponding to the identification number (of the signal responsive medium 1), and the center frequencies (f １, f ２ , f ３ ) are individually set to have mutually different discrete frequencies, and the conversion unit 23 performs a Fourier transform on the response signal to extract information on the center frequency, and converts the response signal into a code by determining whether or not there is a correspondence between the information on all the discrete frequencies and the extracted information on the center frequency.

[0222] With the above configuration, it is possible to identify as a code the identification number set on the signal response medium 1. Furthermore, by appropriately setting the number of discrete frequencies and the number of band-pass filters, it is possible to set a code and identification number with a large amount of information, and the code can be detected via communication through electromagnetic waves.

[0223] In this embodiment, the mounting portion 15 has a flat plate shape (card type, pendant type), the first receiving antenna 112 can receive an oscillation signal (chirp signal) from both main surfaces of the mounting portion 15, the first transmitting antenna 133 can transmit a response signal from both main surfaces of the mounting portion 15, a plurality of second transmitting antennas 213 are connected in parallel to the signal generating portion 211, a plurality of second receiving antennas 221 are connected in parallel to the converting portion 23, and the plurality of second transmitting antennas 213 and the plurality of second receiving antennas 221 form one second transmitting antenna in a first direction (X direction). The antenna 213 and one second receiving antenna 221 are arranged side by side, and the second transmitting antennas 213 and the second receiving antennas 221 are arranged alternately in a second direction (Y direction) perpendicular to the first direction (X direction). The distance between the second transmitting antenna 213 (the center of the second transmitting antenna 213) and the second receiving antenna 221 (the center of the second receiving antenna 221) arranged side by side in the first direction (X direction) is the same as the distance between the first receiving antenna 112 (the center of the first receiving antenna 112) and the first transmitting antenna 133 (the center of the first transmitting antenna 133).

[0224] With the above configuration, multiple possible arrangements of the reader 2 and the signal response medium 1 can be set when the reader 2 transmits an oscillation signal (chirp signal) to the signal response medium 1 and the signal response medium 1 transmits a response signal to the reader 2, making it easy to communicate between the reader 2 and the signal response medium 1.

[0225] The code reading system of this embodiment is a code detection system that includes a (contactless) signal-responsive medium 1, in which a plurality of discrete frequencies different from one another are set in a frequency band (of a chirp signal), and information on the presence or absence of a signal component of each discrete frequency in a response signal is set as one bit, and a code having the number of bits of said information as the identification number of the signal-responsive medium 1, and that includes: a reader 2 that is disposed facing the main surface of the signal-responsive medium 1 (mounting portion 15) and in which the signal-responsive medium 1 is disposed in close proximity, for transmitting an oscillation signal to the signal-responsive medium 1 and receiving a response signal from the signal-responsive medium 1; a signal generating unit 211 that generates the oscillation signal (chirp signal); a first transmitting / receiving antenna 27A in the reader 2 that is disposed in a position facing one of the first receiving antenna 112 and the first transmitting antenna 133 when the signal-responsive medium 1 is disposed in close proximity to the reader 2, and that is capable of transmitting radio waves related to the oscillation signal (chirp signal) and receiving radio waves related to the response signal; a second transmitting / receiving antenna 27B that is arranged at a position facing the other of the first receiving antenna 112 and the first transmitting antenna 133 when the first transmitting / receiving antenna 27A is placed, and that is capable of transmitting radio waves related to an oscillation signal (chirp signal) and receiving radio waves related to a response signal; a converter 23 that converts the response signal into a code; a first connection state in which the signal generator 211 is connected to the first transmitting / receiving antenna 27A and insulated from the second transmitting / receiving antenna 27B, and the converter 23 is connected to the second transmitting / receiving antenna 27B and insulated from the first transmitting / receiving antenna 27A; a switching unit 28 that performs switching control to alternately switch between a first connection state in which the converter 23 is connected to the first transmitting / receiving antenna 27B and insulated from the first transmitting / receiving antenna 27A, and a second connection state in which the converter 23 is connected to the first transmitting / receiving antenna 27A and insulated from the second transmitting / receiving antenna 27B, and in the signal responsive medium 1, the number of band pass filters (BPF1, BPF2, BPF3) is set corresponding to the number of signals of discrete frequencies corresponding to the identification number (of the signal responsive medium 1), and the center frequencies (f １ , f ２ , f ３) are individually set to have mutually different discrete frequencies, and the conversion unit 23 performs a Fourier transform on the response signal to extract information on the center frequency, and converts the response signal into a code by determining whether or not there is a correspondence between the information on all the discrete frequencies and the extracted information on the center frequency.

[0226] With the above configuration, when the first transmitting / receiving antenna 27A functions as a transmitting antenna, the second transmitting / receiving antenna 27B functions as a receiving antenna, and when the first transmitting / receiving antenna 27A functions as a receiving antenna, the second transmitting / receiving antenna 27B functions as a transmitting antenna. Therefore, for example, even if communication between the signal response medium 1 and the reader 2 is disabled when the signal response medium 1 is placed upside down and close to the reader 2, communication will become possible after a predetermined time has elapsed, thereby reducing the operational burden on the user using the signal response medium 1.

[0227] In this embodiment, the mounting portion 15 has a flat plate shape (pendant type), the first receiving antenna 112 is capable of receiving an oscillation signal from both main surfaces of the mounting portion 15, the first transmitting antenna 133 is capable of transmitting a response signal from both main surfaces of the mounting portion 15, and in the reader 2, multiple first transmitting / receiving antennas 27A and multiple second transmitting / receiving antennas 27B are arranged so that one surrounds the other.

[0228] With the above configuration, when the first transmitting / receiving antenna 27A functions as a transmitting antenna, the second transmitting / receiving antenna 27B functions as a receiving antenna, and when the first transmitting / receiving antenna 27A functions as a receiving antenna, the second transmitting / receiving antenna 27B functions as a transmitting antenna. Therefore, for example, when the signal response medium 1 is placed close to the reader 2 with the front / back and orientation of the signal response medium 1 in any position, even if communication between the signal response medium 1 and the reader 2 is not possible, communication becomes possible after a predetermined time has elapsed, thereby reducing the operational burden on the user using the signal response medium 1.

[0229] The signal-responsive medium identification method of this embodiment includes an input unit 11 to which an oscillation signal (chirp signal) whose oscillation frequency changes over time in a predetermined frequency band is input, and a circuit (parallel circuit) in which multiple bandpass filters (BPF1, BPF2, BPF3) that selectively pass signals of different center frequencies in the frequency band are connected in parallel, and the oscillation signal (chirp signal) is input to the circuit (parallel circuit) via the input unit 11, thereby generating multiple response signals having different center frequencies, and an output unit 13 that outputs the response signals.The signal-responsive medium identification method is a signal-responsive medium identification method in which a plurality of discrete frequencies having different frequencies are set in the frequency band and the center frequency is set to one of the discrete frequencies, thereby setting an identification number for the signal-responsive medium 1 by a combination of signal components of the center frequencies in the response signal, and extracts center frequency information from the response signal, and determines whether there is a correspondence between all of the discrete frequency information and the extracted center frequency information, thereby specifying the identification number.

[0230] The above method makes it possible to easily identify the identification number set on the signal response medium 1. Furthermore, by appropriately setting the number of discrete frequencies and the number of band-pass filters, it is possible to set an identification number with a large amount of information.

[0231] The code detection method according to the present embodiment relates to a signal-responsive medium 1 including an input unit 11 to which an oscillation signal (chirp signal) whose oscillation frequency varies over time in a predetermined frequency band is input, a signal processing unit 12 which includes a circuit (parallel circuit) in which a plurality of band-pass filters (BPF1, BPF2, BPF3) are connected in parallel and which selectively pass signals of different center frequencies in the frequency band, and which generates a plurality of response signals having different center frequencies when the oscillation signal (chirp signal) is input to the circuit (parallel circuit) via the input unit 11, and an output unit 13 which outputs the response signals, and in which a plurality of discrete frequencies having different frequencies are set in the frequency band, and a code in which information indicating the presence or absence of a signal component of each discrete frequency in the response signal is one bit and the number of bits is the number of the information, is used as an identification number of the signal-responsive medium 1. A code detection method for detecting a code on a signal-responsive medium (1) in a case where the number of band-pass filters (BPF1, BPF2, BPF3) in the signal-responsive medium (1) is set to correspond to the number of discrete frequencies corresponding to the identification number, and the center frequencies of the band-pass filters (BPF1, BPF2, BPF3) are individually set to be mutually different discrete frequencies, the method comprising a transmitting step of transmitting an oscillation signal (chirp signal) to the signal-responsive medium (1), a receiving step of receiving a response signal transmitted from the signal-responsive medium (1), and a converting step of converting the response signal into a code, in which the converting step performs a Fourier transform on the response signal to extract center frequency information, and converts the response signal into a code by determining whether or not there is a correspondence between all of the discrete frequency information and the extracted center frequency information.

[0232] By using the above method, it is possible to identify as a code the identification number set on the signal response medium 1. Furthermore, by appropriately setting the number of discrete frequencies and the number of band-pass filters, it is possible to set codes and identification numbers with a large amount of information.

[0233] In this embodiment, in the transmission step, the lowest frequency in the frequency band (lower limit frequency (f Ｌ ) to the highest frequency (upper limit frequency (f Ｈ)), and in the conversion step, the response signal is subjected to a Fourier transform to extract information about the center frequency, or the center frequency information of the response signal is identified based on the timing at which the response signal is received, and the response signal is converted into a code by determining whether or not there is a correspondence between the information about all the discrete frequencies and the extracted or identified center frequency information.

[0234] By using the above method, the number of response signals and the discrete frequencies of the response signals can be detected with high accuracy.

[0235] Although an embodiment of the present invention has been described above, the above embodiment merely shows one application example of the present invention, and is not intended to limit the technical scope of the present invention to the specific configuration of the above embodiment.

[0236] 1 Signal response medium 111 Input terminal 112 Input unit Rx1 Receiving antenna 12 Signal processing unit BPF1, BPF2, BPF3 Bandpass filter 121 Ground terminal 131 Output terminal 132 Output unit Tx1 Transmitting antenna 14 Voltage generating circuit 15 Mounting unit 2 Reader 201 Socket 21 Transmitting unit 211 First contact electrode 212 Second contact electrode 213 Third contact electrode Tx2 Transmitting antenna 22 Receiving unit Rx2 Receiving antenna 23 Conversion unit 24 Readout unit 25 Memory unit 26 Display unit 27A Transmitting and receiving antenna 27B Transmitting and receiving antenna 28 Switching unit 31 Ground plate 32 Printed circuit board 33 Microstrip line 34 First microstrip line 35 Second microstrip line 36 Rectangular parallelepiped 4 Wristband S1 Continuous body M1 Perforated 41 Band part 411 Adhesive part 5 Tag S2 Continuous body M2 Perforated 51 Mounting paper 52 Mounting paper

Claims

1. A signal response medium comprising: an input section to which an oscillation signal whose oscillation frequency changes over time in a predetermined frequency band is input; a signal processing section including a circuit in which a plurality of bandpass filters are connected in parallel to selectively pass signals of different center frequencies in the frequency band, the signal processing section generating a plurality of response signals related to the different center frequencies when the oscillation signal is input to the circuit via the input section; and an output section that outputs the response signals.

2. A signal responsive medium as described in claim 1, wherein one of a pair of ends connecting a plurality of said bandpass filters in parallel of said circuit is connected to said input portion, and the other of said pair of ends is connected to said output portion.

3. A signal responsive medium according to claim 1, wherein the oscillation signal is a chirp signal whose oscillation frequency is swept across the frequency band, and the signal processing unit generates the response signal from the chirp signal.

4. A signal responsive medium as claimed in claim 1, wherein the plurality of bandpass filters are resonant circuits having mutually different resonant frequencies, and selectively pass the response signal of the oscillation signal having the resonant frequency as its center frequency.

5. The signal response medium according to claim 1, further comprising a voltage generating circuit that rectifies the oscillation signal or an AC signal different from the oscillation signal to generate a DC voltage, and the signal processing unit is capable of generating the response signal based on the DC voltage of the voltage generating circuit.

6. The signal-responsive medium according to claim 1, further comprising a mounting section on which the input section, the signal processing section, and the output section are mounted, the input section and the output section including an antenna disposed on a main surface of the mounting section.

7. A signal response medium as described in claim 6, wherein the antenna includes a first receiving antenna constituting the input section and a first transmitting antenna constituting the output section, and the first receiving antenna and the first transmitting antenna are arranged at different positions from each other on the main surface of the mounting section.

8. A signal response medium as described in claim 7, wherein, when the oscillation signal is transmitted as radio waves, the first receiving antenna is capable of receiving the radio waves and transmitting the oscillation signal to the signal processing unit, and the first transmitting antenna is capable of transmitting the response signal as the radio waves.

9. The signal responsive medium according to claim 8, wherein the radio wave frequency band is the UHF band.

10. The signal-responsive medium of claim 1, wherein the bandpass filter includes a series circuit of an inductor, a capacitor, and a resistor arranged in that order, with the open end of the inductor connected to the input section and the midpoint of the connection between the capacitor and the resistor connected to the output section.

11. The signal responsive medium according to claim 10, wherein the series circuit is constituted by a lumped constant circuit and / or a distributed constant circuit.

12. A signal-responsive medium as described in claim 10, further comprising a mounting section on which the input section, the signal processing section, and the output section are mounted, wherein an input terminal constituting the input section, an output terminal constituting the output section, and a ground terminal connected to the open end of the resistor are arranged on the mounting section, and the input terminal, the output terminal, and the ground terminal are arranged at different positions on the mounting section.

13. The signal response medium according to claim 6 or 12, wherein the mounting portion has any one of a card shape, a label shape, a key holder shape, and a wristband shape.

14. A signal responsive medium identification system including the signal responsive medium of claim 1, in which a plurality of discrete frequencies different from one another are set in the frequency band and the center frequency is set to one of the discrete frequencies, thereby setting an identification number of the signal responsive medium by a combination of signal components of the center frequencies in the response signal, the signal responsive medium identification system extracting information of the center frequency from the response signal and determining whether there is a correspondence between information of all of the discrete frequencies and the extracted information of the center frequency, thereby identifying the identification number.

15. A signal responsive medium identification system as claimed in claim 14, including a reader transmitting said oscillating signal to said signal responsive medium, said signal responsive medium transmitting said response signal to said reader, and said reader receiving said response signal.

16. A code detection system including the signal responsive medium of claim 1, in which a plurality of discrete frequencies different from one another are set in the frequency band, and information regarding the presence or absence of a signal component of each discrete frequency in the response signal is set as 1 bit, and a code having the number of pieces of information as the number of bits is set to be the identification number of the signal responsive medium, comprising: a transmitting unit which transmits the oscillation signal to the input unit; a receiving unit which receives the response signal transmitted from the output unit; and a converting unit which converts the response signal into the code, in which in the signal responsive medium, the number of the bandpass filters is set corresponding to the number of signals of the discrete frequency corresponding to the identification number, and the center frequencies of the bandpass filters are individually set to be the discrete frequencies different from one another, and the converting unit performs a Fourier transform on the response signal to extract information of the center frequency, and converts the response signal into the code by determining whether there is a correspondence between all of the discrete frequency information and the extracted center frequency information.

17. A code detection system including the signal responsive medium of claim 12, in which a plurality of discrete frequencies different from one another are set in the frequency band, and information on the presence or absence of a signal component of each discrete frequency in the response signal is set as one bit, and a code having the number of bits of the information is set as the identification number of the signal responsive medium, comprising: a reader for contacting the signal responsive medium to transmit the oscillation signal to the signal responsive medium and to receive the response signal from the signal responsive medium; a transmitting section in the reader, which is located at a position where it contacts the input terminal when the signal responsive medium contacts the reader, and transmits the oscillation signal to the input terminal; a grounding section electrically connected to the transmitting section, which is located at a position where it contacts the ground terminal when the input terminal contacts the transmitting section; a receiving section in the reader, which is located at a position where it contacts the output terminal when the ground terminal contacts the grounding section, and receives the response signal transmitted from the output terminal; and a conversion section for converting the response signal into the code, in which in the signal responsive medium: a code detection system in which the number of bandpass filters is set corresponding to the number of signals of the discrete frequency corresponding to the identification number, and the center frequencies of the bandpass filters are individually set to be the discrete frequencies different from each other, the signal processing unit is grounded via the grounding unit so that it is possible to generate the response signal from the oscillation signal, and the conversion unit performs a Fourier transform on the response signal to extract information of the center frequency, and converts the response signal into the code by determining whether or not there is a correspondence between the information of all the discrete frequencies and the extracted information of the center frequency.

18. A code detection system as described in claim 16 or claim 17, wherein the transmitting unit changes the frequency of the oscillation signal so as to sweep from the lowest frequency to the highest frequency in the frequency band, and the converting unit converts the response signal into the code by performing a Fourier transform on the response signal to extract information of the center frequency, or identifying information of the center frequency of the response signal based on the timing of the response signal received by the receiving unit, and determining whether there is a correspondence between information of all of the discrete frequencies and the extracted or identified information of the center frequency.

19. A code detection system including the signal responsive medium according to claim 8 or 9, in which a plurality of discrete frequencies different from one another are set in the frequency band, and information on the presence or absence of a signal component of each discrete frequency in the response signal is set as one bit, and a code having the number of bits of the information is set as the identification number of the signal responsive medium, comprising: a reader facing the main surface of the signal responsive medium and arranged in close proximity to the signal responsive medium, for transmitting the oscillation signal to the signal responsive medium and receiving the response signal from the signal responsive medium; a signal generating unit that generates the oscillation signal; a second transmitting antenna in the reader, arranged in a position facing the first receiving antenna when the signal responsive medium is arranged in close proximity to the reader, for transmitting the radio waves related to the oscillation signal to the first receiving antenna; a second receiving antenna in the reader, arranged in a position facing the first transmitting antenna when the first receiving antenna is arranged in close proximity to the second transmitting antenna, for receiving the radio waves related to the response signal transmitted from the first transmitting antenna; and a conversion unit that converts the response signal into the code, in which in the signal responsive medium: a code detection system in which the number of bandpass filters is set corresponding to the number of signals of the discrete frequency corresponding to the identification number, and the center frequencies of the bandpass filters are individually set to be the discrete frequencies different from each other, and the conversion unit performs a Fourier transform on the response signal to extract information of the center frequency, and converts the response signal into the code by determining whether or not there is a correspondence between the information of all the discrete frequencies and the extracted information of the center frequency.

20. The code detection system described in claim 19, wherein the mounting portion has a flat plate shape, the first receiving antenna is capable of receiving the oscillation signal from both main surfaces of the mounting portion, the first transmitting antenna is capable of transmitting the response signal from both main surfaces of the mounting portion, the second transmitting antennas are connected in parallel to the signal generating portion, the second receiving antennas are connected in parallel to the converting portion, the second transmitting antennas and the second receiving antennas are arranged such that one second transmitting antenna and one second receiving antenna are aligned with each other in a first direction and the second transmitting antennas and the second receiving antennas are alternately aligned with each other in a second direction perpendicular to the first direction, and the spacing between the second transmitting antenna and the second receiving antenna aligned in the first direction is the same as the spacing between the first receiving antenna and the first transmitting antenna.

21. A code detection system including the signal responsive medium according to claim 8 or 9, in which a plurality of discrete frequencies different from each other are set in the frequency band, information on the presence or absence of a signal component of each discrete frequency in the response signal is set as 1 bit, and a code having the number of bits of the information is set as an identification number of the signal responsive medium, comprising: a reader facing a main surface of the signal responsive medium and arranged adjacent to the signal responsive medium for transmitting the oscillation signal to the signal responsive medium and receiving the response signal from the signal responsive medium; a signal generating unit for generating the oscillation signal; and a first transmitting / receiving antenna arranged in the reader to face one of the first receiving antenna and the first transmitting antenna when the signal responsive medium is arranged adjacent to the reader, the first transmitting / receiving antenna being capable of transmitting the radio wave related to the oscillation signal and receiving the radio wave related to the response signal, the reader includes a second transmitting / receiving antenna arranged at a position facing the other of the first receiving antenna and the first transmitting antenna when the first transmitting / receiving antenna is arranged close to one of the first receiving antenna and the first transmitting antenna, the second transmitting / receiving antenna being capable of transmitting the radio wave related to the oscillation signal and receiving the radio wave related to the response signal, a conversion unit that converts the response signal into the code, and a switching unit that executes switching control to alternate between a first connection state in which the signal generating unit is connected to the first transmitting / receiving antenna and insulated from the second transmitting / receiving antenna and the conversion unit is connected to the second transmitting / receiving antenna and insulated from the first transmitting / receiving antenna, and a second connection state in which the signal generating unit is connected to the second transmitting / receiving antenna and insulated from the first transmitting / receiving antenna and the conversion unit is connected to the first transmitting / receiving antenna and insulated from the second transmitting / receiving antenna, and The conversion unit performs a Fourier transform on the response signal to extract information about the center frequency, and converts the response signal into the code by determining whether or not there is a correspondence between information about all of the discrete frequencies and the extracted information about the center frequency.

22. A code detection system as described in claim 21, wherein the mounting portion has a flat plate shape, the first receiving antenna is capable of receiving the oscillation signal from both main surfaces of the mounting portion, the first transmitting antenna is capable of transmitting the response signal from both main surfaces of the mounting portion, and in the reader, the first transmitting / receiving antenna and the second transmitting / receiving antenna are arranged in multiple numbers so that one of them surrounds the other.

23. A signal-responsive medium identification method for a signal-responsive medium including an input section to which an oscillation signal whose oscillation frequency varies over time in a predetermined frequency band is input, a circuit in which a plurality of bandpass filters are connected in parallel to selectively pass signals of different center frequencies in the frequency band, said signal processing section generating a plurality of response signals related to the different center frequencies as the oscillation signal is input to said circuit via said input section, and an output section to output the response signals, wherein a plurality of discrete frequencies having different frequencies are set in the frequency band and the center frequency is set to one of the discrete frequencies, thereby setting an identification number of the signal-responsive medium by a combination of signal components of the center frequencies in the response signals, the method extracting information of the center frequency from the response signal and determining whether there is a correspondence between all of the discrete frequency information and the extracted center frequency information, thereby identifying the identification number.

24. A code detection method for detecting a code on a signal-responsive medium, the method comprising: an input section to which an oscillation signal whose oscillation frequency varies over time in a predetermined frequency band is input; a circuit in which a plurality of band-pass filters are connected in parallel and which selectively pass signals of different center frequencies in the frequency band, the signal processing section generating a plurality of response signals related to the different center frequencies as a result of the oscillation signal being input to the circuit via the input section; and an output section outputting the response signals, the method comprising: a plurality of discrete frequencies different from each other in the frequency band are set; information on the presence or absence of a signal component of each discrete frequency in the response signal is one bit, the number of the band-pass filters is set in the signal-responsive medium corresponding to the number of the discrete frequencies corresponding to the identification number so that a code having the number of bits of the information becomes an identification number of the signal-responsive medium; the method comprising: a transmitting step of transmitting the oscillation signal to the signal-responsive medium; a receiving step of receiving the response signal transmitted from the signal-responsive medium; and a converting step of converting the response signal into the code, A code detection method in which, in the conversion step, the response signal is Fourier transformed to extract information about the center frequency, and the response signal is converted into the code by determining whether or not there is a correspondence between information about all of the discrete frequencies and the extracted information about the center frequency.

25. A code detection method as described in claim 24, wherein, in the transmitting step, the frequency of the oscillation signal is changed so as to sweep from the lowest frequency to the highest frequency in the frequency band, and, in the converting step, the response signal is subjected to a Fourier transform to extract information of the center frequency, or the center frequency information of the response signal is identified based on the timing of receiving the response signal, and the response signal is converted into the code by determining whether or not there is a correspondence between information of all of the discrete frequencies and the extracted or identified information of the center frequency.

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