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

Abstract

To provide a signal response medium, a code detection system, and a code detection method in which detection accuracy of a response signal is improved.SOLUTION: A signal response medium includes: an input unit to which a chirp signal whose oscillation frequency changes with time in a predetermined frequency band is input; a signal processing unit that includes a parallel circuit in which a plurality of band-pass filters that selectively pass signals having a center frequency different from each other in the frequency band are connected in parallel, and generates a plurality of response signals related to the center frequencies different from each other when a chirp signal is input to the parallel circuit via the input unit; and an output unit that outputs a response signal.SELECTED DRAWING: Figure 1

Description

[Technical field]

[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. [Background technology]

[0002] Patent Document 1 discloses that in a responder medium that receives a chirp signal and replies with a response signal, multiple LC circuits are hung on the 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. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 2972040 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in Patent Document 1, the response signal is generated by propagating the chirp signal 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 decreases the detection accuracy of the response signal.

[0005] Therefore, an object of one embodiment of the present invention is to improve the detection accuracy of a response signal. [Means for solving the problem]

[0006] 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 bandpass 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 relating 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. Effect of the Invention

[0007] According to one aspect of the present invention, an oscillation signal is input to all bandpass filters at the same time, and each bandpass filter selectively passes a different center frequency, generating a plurality of response signals that have passed through each bandpass filter at different times. Therefore, the response signal that has passed through one bandpass filter is generated without being influenced by the other bandpass filters, and the response signals that have passed through each bandpass filter do not overlap in time, so that deterioration of the response signal in the frequency direction and the time direction can be suppressed. Therefore, deterioration of the S / N ratio of the response signal in the frequency direction and the time direction can be suppressed. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing a signal-responsive medium (card type) of 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. [Diagram 2] FIG. 2 is a circuit diagram of a signal responsive medium. [Diagram 3] FIG. 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 a signal-responsive medium. [Figure 4] FIG. 4 is a circuit diagram of a bandpass filter. [Diagram 5] FIG. 5 is a Bode plot of the bandpass filter shown in FIG. [Figure 6] FIG. 6 is a diagram showing the results of a frequency characteristic analysis of a response signal output from a signal response medium. [Figure 7] FIG. 7 is a diagram showing a result of a transient response analysis of a response signal when a chirp signal is input to a signal response medium. [Figure 8] FIG. 8 is a schematic diagram showing an inductor constituting a bandpass filter configured with a distributed constant circuit. [Figure 9] FIG. 9 is a schematic diagram showing a case where the capacitors constituting the bandpass filter are configured by distributed constant circuits. [Figure 10] FIG. 10 is a schematic diagram showing a configuration in which resistors constituting a bandpass filter are configured using distributed constant circuits. [Figure 11] 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. [Figure 12] FIG. 12 is a plan view of the signal response medium (card type) and the reader constituting the code reading system of the first embodiment, showing the state in which the signal response medium is inserted into the reader. [Figure 13] FIG. 13 is a side view of the reader constituting the code reading system of the first embodiment. [Figure 14] FIG. 14 is a block diagram of the code reading system of the first embodiment. [Figure 15] FIG. 15 is a schematic diagram of a signal response medium (card type) and a reader which constitute the code reading system of the second embodiment. [Figure 16] FIG. 16 is a schematic diagram showing a case where a signal response medium (card) is collated by a reader in the code reading system of the second embodiment. [Figure 17] FIG. 17 is a block diagram of a code reading system according to the second embodiment. [Figure 18] FIG. 18 shows a modified example of the reader constituting the code reading system of the second embodiment. [Figure 19] FIG. 19 is a block diagram of a code reading system according to the third embodiment. [Figure 20]FIG. 20 is a schematic diagram of a reader constituting the code reading system of the third embodiment. [Figure 21] FIG. 21 is a schematic diagram of a signal response medium (key holder type) constituting a code reading system according to a modified example of the third embodiment. [Figure 22] FIG. 22 is a schematic diagram of a reader constituting a code reading system according to a modified example of the third embodiment. [Figure 23] FIG. 23 is a schematic diagram of a wristband equipped with a signal responsive medium. [Figure 24] FIG. 24 is a schematic diagram showing an example of a wristband equipped with a signal response medium wound in a roll. [Diagram 25] FIG. 25 is a schematic diagram showing the state of a tag with a signal responsive medium mounted thereon before it is cut off. [Figure 26] FIG. 26 is a schematic diagram showing the state of the tag with the signal responsive medium mounted thereon after it has been cut off. [Figure 27] FIG. 27 is a schematic diagram showing a state before the label-type signal response medium is peeled off from the mount. [Figure 28] FIG. 28 is a schematic diagram showing the state after the label-type signal response medium has been peeled off from the mount. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The embodiments described below are not limited to the drawings which are illustrated by the brief description of the drawings.

[0010] 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, and 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, 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.

[0011] According to the first embodiment, an oscillation signal is input to all bandpass filters at the same time, and each bandpass filter selectively passes different frequencies, generating a plurality of response signals that have passed through each bandpass filter at different times. Therefore, a response signal that has passed through one bandpass filter is generated without being affected by other bandpass filters, and the response signals that have passed through each bandpass filter do not overlap in time, so that deterioration of the response signal in the frequency direction and time direction can be suppressed. Therefore, deterioration of the S / N ratio of the response signal in the frequency direction and time direction can be suppressed.

[0012] A second form of the present invention is a signal responsive medium in accordance with the first form, wherein one of a pair of ends connecting a plurality of the bandpass filters of the circuit in parallel is connected to the input portion, and the other of the pair of ends is connected to the output portion.

[0013] According to the second mode, the oscillation signal before passing through the signal processing unit is not included in the response signal, so that a decrease in the S / N ratio of the response signal can be suppressed.

[0014] A third form of the present invention is a signal response medium according to the first or second form, 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.

[0015] According to the third aspect, it is possible to easily generate a response signal using a plurality of band pass filters.

[0016] A fourth form of the present invention is a signal response medium in any one of the first to third forms, wherein the multiple 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.

[0017] According to the fourth embodiment, a bandpass filter with a high Q value can be constructed, and even if the difference between the resonant frequencies of two bandpass filters having 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. Also, an anti-resonant state appears in a parallel circuit of two bandpass filters having different resonant frequencies, and the anti-resonant frequency appears between the two resonant frequencies. As a result, a dip related to the anti-resonant frequency appears between the two response signals in the frequency domain, and the two response signals can be more clearly separated in the frequency direction and the time direction.

[0018] 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 capable of generating the response signal based on the potential of the low-voltage side of the DC voltage of the voltage generation circuit.

[0019] According to the fifth aspect, even if the signal responsive medium is not configured to be grounded to the outside, the response signal can be generated stably.

[0020] A sixth form of the present invention is any one of the first to fifth forms, further including a mounting part on which the input part, the signal processing part, and the output part are mounted, and the input part and the output part are signal response media including an antenna arranged on a main surface of the mounting part.

[0021] According to the sixth aspect, a non-contact type signal response medium can be easily constructed.

[0022] A seventh aspect of the present invention is a signal response medium according to the sixth aspect, 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 a main surface of the mounting section.

[0023] 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 responsive medium and receives a response signal from the signal responsive medium.

[0024] The eighth aspect of the present invention is the seventh aspect, 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.

[0025] According to the eighth embodiment, wireless communication using radio waves between the signal response medium and the reader can be performed with a simple configuration.

[0026] 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.

[0027] According to the ninth embodiment, 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.

[0028] A tenth aspect of the present invention is a signal responsive medium in any one of the first to ninth aspects, wherein the bandpass filter includes a series circuit in which an inductor, a capacitor, and a resistor are arranged in that 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.

[0029] According to the tenth aspect, a bandpass filter can be constructed with a simple configuration.

[0030] The eleventh form of the present invention is the signal responsive medium of the tenth form, wherein the series circuit is a lumped constant circuit and / or a distributed constant circuit.

[0031] According to the eleventh embodiment, it is possible to increase the variation in the creation of each impedance element constituting the series circuit. In particular, when the series circuit is constructed entirely of distributed constant circuits, the entire circuit can be formed in a small size, so that the information density per unit area (DPS) can be increased. In addition, a bandpass filter with a high Q value can be constructed even in distributed constant circuits, so that the information density per unit frequency (DPF) can be increased.

[0032] A twelfth form of the present invention is a signal responsive medium according to the tenth or eleventh form, further comprising a mounting part on which the input part, the signal processing part, and the output part are mounted, and the mounting part has an input terminal constituting the input part, an output terminal constituting the output part, and a ground terminal connected to the open end of the resistor arranged thereon, the input terminal, the output terminal, and the ground terminal being arranged at different positions from each other on the mounting part.

[0033] According to the twelfth embodiment, the contact-type signal response medium 1 can be easily constructed.

[0034] The thirteenth aspect of the present invention is the sixth or twelfth aspect, wherein the mounting portion is a signal response medium having any one of a card shape, a label shape, a key holder (pendant) shape, and a wristband shape.

[0035] According to the thirteenth aspect, the application range of the signal responsive medium can be set to a wide range.

[0036] A 14th form of the present invention is a signal responsive medium identification system which includes the signal responsive medium of any one of the 1st to 13th 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, thereby setting an identification number of the signal responsive medium by a combination of signal components of each center frequency in the response signal, and which 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.

[0037] According to the fourteenth embodiment, 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.

[0038] A 15th form of the present invention is a signal responsive medium identification system according to the 14th form, which includes a reader that transmits the oscillation signal to the signal responsive medium, the signal responsive medium transmits the response signal to the reader, and the reader receives the response signal.

[0039] According to the fifteenth aspect, communication between the signal responsive medium and the reader can be performed in a non-contact manner.

[0040] A 16th form of the present invention is a code detection system including the signal responsive medium of any one of the 1st to 13th forms, in which a plurality of discrete frequencies different from each other 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 1 bit, and a code having the number of pieces of information as the number of bits is set to be an identification number of the signal responsive medium, the code detection system including a transmitting unit that transmits the oscillation signal to the input unit, a receiving unit that receives the response signal transmitted from the output unit, and a conversion unit that converts the response signal to the code, in which the number of the bandpass filters in the signal responsive medium 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.

[0041] According to the sixteenth embodiment, the identification number set in the signal response medium can be identified as a code. Also, by appropriately setting the number of discrete frequencies and the number of band pass filters, a code and an identification number with a large amount of information can be set.

[0042] A 17th form of the present invention is a code detection system including the signal responsive medium of any one of the 1st to 13th forms, 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 pieces of information as a bit number is set to be an identification number of the signal responsive medium, the code detection system including: a reader for contacting the signal responsive medium to transmit the oscillation signal to the signal responsive medium and receiving the response signal from the signal responsive medium; a transmitting unit, in the reader, arranged at a position where it contacts the input terminal when the signal responsive medium contacts the reader, transmitting the oscillation signal to the input terminal; and a contact, electrically connected to the transmitting unit, arranged at a position where it contacts the ground terminal when the input terminal contacts the transmitting unit in the reader. a ground section, a receiving section in the reader that is disposed at a position where the ground terminal comes into contact with the output terminal when the ground terminal comes into contact with the ground section and receives the response signal transmitted from the output terminal, and a conversion section that converts 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 frequency 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 section is grounded via the ground section so that it is possible to generate the response signal from the oscillation signal, and the conversion section 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 all of the discrete frequency information and the extracted center frequency information.

[0043] According to the seventeenth embodiment, the identification number set in the signal response medium can be identified as a code. Also, 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 the contact electrodes.

[0044] The 18th aspect of the present invention is the 16th or 17th aspect, wherein the transmission unit changes the frequency of the oscillation signal so as to sweep from the lowest frequency to the highest frequency in the frequency band; The conversion unit is a code detection system that converts the response signal into the code by performing a Fourier transform on the response signal to extract the center frequency component, 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 or not there is a correspondence between information of all of the discrete frequencies and the extracted or identified center frequency information.

[0045] According to the eighteenth mode, the number of response signals and the discrete frequencies of the response signals can be detected with high accuracy.

[0046] A 19th aspect of the present invention is a code detection system including the signal responsive medium of the 8th or 9th aspect, 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 pieces of information as a bit number 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 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 in the reader, a second receiving antenna that is arranged in a position facing the first transmitting antenna when the first receiving antenna is arranged in close proximity to the second transmitting antenna and receives 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, wherein in the signal response medium, the number of the band-pass filters is set corresponding to the number of signals of the discrete frequency 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 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 all of the discrete frequency information and the extracted center frequency information.

[0047] According to the nineteenth embodiment, the identification number set in the signal response medium can be identified as a code. Also, 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 through communication via electromagnetic waves.

[0048] A twentieth aspect of the present invention is a code detection system according to the nineteenth aspect, wherein the mounting portion has a flat 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 in a second direction perpendicular 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.

[0049] According to the 20th embodiment, multiple possible arrangements of the reader and the signal responsive medium are set when the reader transmits an oscillation signal to the signal responsive medium and the signal responsive medium transmits a response signal to the reader, thereby facilitating communication between the reader and the signal responsive medium.

[0050] A 21st aspect of the present invention is a code detection system including the signal responsive medium of the 8th or 9th aspect, wherein a plurality of discrete frequencies different from each other 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 1 bit, and a code having the number of pieces of information as a number of bits is set so as to be an identification number of the signal responsive medium, the code detection system including 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, a first transmitting / receiving antenna in the reader, arranged at 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, and an antenna for transmitting the oscillation signal to the signal responsive medium, the signal generating unit being arranged in close proximity to the main surface of the signal responsive medium, the signal generating unit being arranged in close proximity to the main surface of the signal responsive medium, 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 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 conversion unit is connected to the second transmitting / receiving antenna and insulated from the first transmitting / receiving antenna and the signal generating unit is connected to the first transmitting / receiving antenna and insulated from the second transmitting / receiving antenna, wherein in the signal response medium, the number of the bandpass filters is set corresponding to the number of signals of the discrete frequencies 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 all of the discrete frequency information and the extracted center frequency information.

[0051] According to the twenty-first embodiment, 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 impossible 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 who uses the signal response medium.

[0052] The 22nd form of the present invention is a code detection system according to the 21st form, wherein the mounting portion has a flat 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.

[0053] According to the twenty-second embodiment, 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 / back and orientation of the signal response medium being arbitrary, 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 a user who uses the signal response medium.

[0054] 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 changes 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, 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 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 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 all of the discrete frequency information and the extracted center frequency information, thereby identifying the identification number.

[0055] According to the twenty-third embodiment, 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.

[0056] A 24th aspect 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 are connected in parallel to selectively pass signals of different center frequencies in said frequency band, said signal processing section generating a plurality of response signals relating to said different center frequencies by inputting said oscillation signal to said circuit via said input section, and an output section to output said response signals, wherein a plurality of discrete frequencies different from each other 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 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 bandpass filters is set corresponding to the number of corresponding discrete frequencies and the center frequencies of the bandpass filters are individually set to be different discrete frequencies from each other, the code detection method including 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, in which in the converting step, a Fourier transform is performed on the response signal to extract information of the center frequency, and a determination is made as to whether or not there is a correspondence between information of all of the discrete frequencies and the extracted information of the center frequency, thereby converting the response signal into the code.

[0057] According to the 24th embodiment, the identification number set in the signal response medium can be identified as a code. Also, by appropriately setting the number of discrete frequencies and the number of band pass filters, a code and an identification number with a large amount of information can be set.

[0058] A 25th aspect of the present invention is a method for converting a response signal into a code by determining whether there is a correspondence between all of the discrete frequency information and the extracted or identified central frequency information, and converting the response signal into the code by performing a Fourier transform on the response signal in the transmitting step and extracting information about the central frequency from the lowest frequency to the highest frequency in the frequency band in the converting step, or determining whether there is a correspondence between all of the discrete frequency information and the extracted or identified central frequency information.

[0059] According to the 25th mode, the number of response signals and the discrete frequencies of the response signals can be detected with high accuracy.

[0060] Hereinafter, an embodiment will be described with reference to the drawings.

[0061] [Basic configuration of signal response medium 1] Fig. 1 is a diagram showing a 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 by the signal-responsive medium 1. Fig. 2 is a circuit diagram of the signal-responsive medium 1.

[0062] 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).

[0063] In addition to the non-contact type signal responsive medium 1 shown in FIG. 1, the present invention also includes a contact type signal responsive medium 1 shown in, for example, FIGS. 11 and 12 described later.

[0064] A chirp signal, which will be described later, is input to the first receiving antenna 112 .

[0065] 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.

[0066] The first transmitting antenna 133 outputs (transmits) the response signal to the outside.

[0067] 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.

[0068] The open ends of inductor L1, inductor L2, and inductor L3 are connected in parallel and connected to the input section 11 (first receiving antenna 112), and the connection midpoint of capacitor C1 and resistor R1, the connection midpoint of capacitor C2 and resistor R2, and the connection midpoint of capacitor C3 and resistor R3 are connected in parallel and connected to the output section 13 (first transmitting antenna 133).

[0069] The open end of the resistor R1, the open end of the resistor R2, and the open end of the resistor R3 are grounded.

[0070] In the bandpass filter (BPF1), the inductor L1 and resistor R1 function as a lowpass filter, and the capacitor C1 and resistor R1 function as a highpass filter, thereby forming a bandpass filter, and the same is true for the bandpass filters (BPF2, BPF3).

[0071] The signal processing unit 12 is a parallel circuit in which bandpass filters (BPF1, BPF2, BPF3) having different resonant frequencies are connected in parallel.

[0072] [Chirp Signals and Discrete Frequencies] 3 is a diagram showing the relationship between the frequency band of the 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:

number

[0073] 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:

number

[0074] where f H is the upper limit frequency (final frequency) higher than the lower limit frequency, and T is f L From f H The time (period) required to sweep from 0 to 1. A sinusoidal linear chirp signal in the time domain is given as follows:

number

[0075] Here, θ 0 is the initial phase (time t=0).

[0076] In this embodiment, the lower limit frequency (f L ) and upper frequency (f H ) is used as the input signal.

[0077] In this embodiment, as shown in FIG. 3, n discrete frequencies (f 1 , f 2 , f 3 , f n-1 , f n ) is set. Note that f 1 <f 2<f 3 <... <f n-1 <f n However, the magnitude relationship between the number and the frequency can be set arbitrarily. 1 The lower limit frequency (f L ), and then set it to f n The upper limit frequency (f H ) may be set.

[0078] In this embodiment, information on the presence or absence of a signal relating to each discrete frequency is set as 1 bit, and a code having the number of pieces of information (n pieces) as the number of bits (number of digits) is set to represent the identification number of the signal response medium 1.

[0079] 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 frequency (center frequency) of each bandpass filter is set to any one of the mutually different discrete frequencies. Furthermore, the number of bandpass filters and the resonant frequency (center frequency) of the signal processing unit 12 of this embodiment are set so as to become the identification number of the signal responsive medium 1 having the signal processing unit 12.

[0080] 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 = 0), the number of bandpass filters (BPF1, BPF2, BPF3) is set to three, and the resonant frequencies of each bandpass filter are set to different values. 1 , f 2 , f 3 is set to.

[0081] Therefore, when a chirp signal is input to the signal processing unit 12, the center frequency is f 1The signal component (response signal) with center frequency f 2 The signal component (response signal) with center frequency f 3 The signal component (response signal) is output.

[0082] Therefore, the reader 2 (see FIG. 14) receives multiple response signals and 1 From f n By determining the presence or absence of signal components up to , 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 bandpass filters and their central frequencies (resonant frequencies) are set so that the number of multiple response signals or the central frequencies of the response signals are different from each other.

[0083] 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 identified based on the timing of reception of each response signal by the reader 2 (see FIG. 11, etc.).

[0084] As described above, the signal response medium 1 does not include an IC (Integrated Circuit) chip for conventional 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.

[0085] [Bandpass filter characteristics] Fig. 4 is a circuit diagram of a bandpass filter. Fig. 5 is a Bode plot of the bandpass filter shown in Fig. 4. The inventors of the present application have studied the frequency response of a bandpass filter (BPF). The bandpass filter (BPF) shown in Fig. 4 is one of the bandpass filters (BPF1, BPF2, BPF3) shown in Fig. 2, and has a series circuit of an inductor L, a capacitor C, and a resistor R, with the open end of the inductor L being the input side (vi) of the chirp signal, the open end of the resistor R being grounded, and the connection midpoint between the capacitor C and the resistor R being the output side (vo) of the response signal.

[0086] The transfer function of a bandpass filter (BPF) is as follows:

number

[0087] 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 plot shown in Figure 5 was obtained.

[0088] As shown in Figure 5, the phase also suddenly inverts at the resonant frequency (center frequency) where the gain peaks. In addition, the Q value, which is the sharpness of the gain centered on the resonant frequency, is 63.24, and the damping ratio ζ is also a good value of 0.079.

[0089] Therefore, it can be seen that for two response signals that are adjacent to each other in frequency and 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].

[0090] [Response signal generated by signal response medium 1] Fig. 6 is a diagram showing a frequency characteristic analysis result of a response signal output from the signal responsive medium 1. Fig. 7 is a diagram showing a transient response analysis result of a response signal when a chirp signal is input to the signal responsive medium 1.

[0091] 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] with T = 10 [ms] was used, and the signal was output as the following function with an amplitude of 3 [V].

number

[0092] In Figure 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. This results in a resonant frequency (f 1 ) to 348[MHz], and set the resonant frequency (f 2 ) to 357 [MHz], and set the resonant frequency (f 3 ) was set to 366 [MHz] and Δf = 9 [MHz].

[0093] As shown in FIG. 6 (result of frequency analysis), even when Δf is set to 9 [MHz], the response signal output from the signal processing unit 12 is output from the band pass filter (BPF1) and has a resonant frequency (f 1 ) is the center frequency of the response signal (f 1 ) and the resonant frequency (f 2 ) is the center frequency of the response signal (f 2 ) and the resonant frequency (f 3 ) is the center frequency of the response signal (f 3 ) can be seen to be separable.

[0094] 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 (f3 The Q value of the response signal (f 1 ) half-width is 3.88[MHz], and the response signal (f 2 ) half-width is 4.08[MHz], and the response signal (f 3 ) was obtained as 4.29 [MHz]. Therefore, it is clear that the response signal can be separated even when Δf is set to about 4 [MHz].

[0095] Furthermore, the response signal (f 1 ) and the response signal (f 2 ), there is a dip (f 12 =352[MHz]) is generated, and a response signal (f 2 ) and the response signal (f 3 ) during which the gain decreases sharply (f 23 =362[MHz]) is occurring.

[0096] Dip (f 12 ) corresponds to the anti-resonance frequency of the parallel circuit of the bandpass filter (BPF1) and the bandpass filter (BPF2), and the dip (f 23 ) corresponds to the anti-resonance frequency in the parallel circuit of the bandpass filter (BPF2) and the bandpass filter (BPF3).

[0097] In addition, since the anti-resonance frequency of the parallel circuit of the bandpass filter (BPF1) and the bandpass filter (BPF3) overlaps with the resonant frequency of the bandpass filter (BPF2), it does not appear as a dip in the frequency analysis results.

[0098] In this way, in two bandpass filters having resonant frequencies adjacent to each other in frequency, an anti-resonant frequency appears between two different resonant frequencies. Therefore, a dip related to the anti-resonant frequency occurs between multiple response signals having different center frequencies, so 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.

[0099] 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 The interval between and time t 2 and time t 3 The interval is 5 μs.

[0100] 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 bandpass filter (BPF1) and the bandpass filter (BPF2) becomes anti-resonant, and time t 23 is the time when the parallel circuit of the bandpass filter (BPF2) and bandpass filter (BPF3) enters an anti-resonant state, and at this time a dip occurs in the transient response analysis results. Therefore, a dip related to the anti-resonant 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.

[0101] From the above results, it can be seen that the configuration with bandpass filters connected in parallel makes it possible to 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.

[0102] [Number of codes in signal processing unit 12] When n discrete frequencies with the above-mentioned Δf bandwidth are set and the number of bandpass 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= 390 [MHz], Δf = 10 [MHz], n = 20 discrete frequencies can be set. When there are five bandpass filters, 20 C 5 = 658,008 possible codes, which can be used as a 19-bit (523,288) code. Also, when there are 10 bandpass filters, 20 C 10 = 847,660,528 possible codes, which can be used as a code equivalent to 29 bits (536,870,912).

[0103] [Distributed constant circuit] Fig. 8 is a schematic diagram of an inductor constituting a bandpass filter configured with a distributed constant circuit. Fig. 9 is a schematic diagram of a capacitor constituting a bandpass filter configured with a distributed constant circuit. Fig. 10 is a schematic diagram of a resistor constituting a bandpass filter configured with a distributed constant circuit.

[0104] 8, the distributed constant circuit of inductor L is formed by laminating an insulating printed circuit board 32 having a thickness H on a conductive ground plate 31, and disposing a conductive (copper foil or the like) microstrip line 33 having a width W and a length L1 on the printed circuit board 32. For example, FR4 (GE4F, a standard of the National Electrical Manufacturers Association (NEMA) and the American National Standards Institute (ANSI), and a JIS standard) is suitable for the printed circuit board 32.

[0105] 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.

[0106] As shown in FIG. 9, the distributed constant circuit of capacitor C is configured such that a first microstrip line 34 having a width W1 and a second microstrip line 35 having a width W2 are arranged facing each other with a gap of width s on a printed circuit board 32 similar to that described above.

[0107] The inventor of the present application then inputted the information of H (=1.6[mm]), W1, W2, and s into the microstrip gap model (Stefan John: https: / / qucs.sourceforge.net / tech / node79.html) and examined the dimensions for a capacitor C of 5.1[pF]. As a result, W1 = 0.1[mm], W2 = 0.2[mm], and s = 0.43[mm] were obtained.

[0108] As shown in Fig. 10, the distributed constant circuit of resistor R can be expressed as a conductive rectangular parallelepiped 36 with a length L2 and a cross-sectional area S. If copper (Cu) (resistivity ρ = 1.72 [Ω cm]) is used as the material of resistor R, then in order for 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.

[0109] If a series circuit is formed with an inductor L, a capacitor C, and a resistor R, the longitudinal dimension will be slightly longer than L1+s+L2 (for example, 55 mm), and the lateral dimension will be the cross-sectional area S of the resistor R (2 mm). The area occupied by one bandpass filter will be 0.55×0.2=0.09 cm 2 ]

[0110] 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]).

[0111] When the bandpass filter of the present invention is formed as a distributed constant circuit as described above, the area occupied by one bandpass filter is 0.09 cm2 as described above. 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 [bit / GHz]. On the other hand, for conventional media, DPS=26[bit / cm 2 ], DPF=25[bit / GHz]. The present invention achieves a DPS of 10 2 times, 10 times with DPF 5 There is a performance difference of 2 times.

[0112] Let us now consider the case where the bandpass filter is constructed using a lumped constant circuit. In this case, the inductor (40[nH]) has a length of 1.0[mmm], a width of 0.5[mm], and a depth of 0.5[mm] (e.g., manufactured by Murata Manufacturing, 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 an LCR series circuit, 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 as above, it is 3 [cm 2 ], but in this case DPS = 2.1 × 10 3 [bit / cm 2 ], DPF = 2.1 × 10 6 From the above, even if the bandpass filter of the present invention is constructed using a lumped constant circuit, the DPS is 0.67×10 2 times, and 0.67×10 for DPF. 5 There is a performance difference of 2x.

[0113] [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 constituting the code reading system of the first embodiment, showing a 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 constituting the code reading system of the first embodiment, showing a state after the signal response medium 1 is inserted into the reader 2. Fig. 13 is a side view of the reader 2 constituting the code reading system of the first embodiment. Fig. 14 is a block diagram of the code reading system of the first embodiment.

[0114] 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.

[0115] As the signal response medium 1, a card type (credit card, SIM card) (Figs. 11 and 12) or a key type is applied. As the reader 2, a slide type or a plug-in type (Figs. 11 and 12) is applied.

[0116] 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, a ground terminal 121, and an output terminal 131 are arranged at different positions on the main surface (surface forming the outer shape of the card) of the mounting section 15. Note that the signal processing section 12 is omitted in FIGS.

[0117] As shown in Fig. 13, the reader 2 has a socket 204 for inserting the signal response medium 1. On the side wall (bottom surface) of the socket 204, there are arranged a first contact electrode 201 constituting the transmitting unit 21 (Fig. 14) for transmitting a chirp signal, a second contact electrode 202 electrically connected to the transmitting unit 21 (Fig. 14) and grounded, and a third contact electrode 203 constituting the receiving unit 22 (Fig. 14) for receiving a response signal.

[0118] As shown in FIG. 13, first contact electrode 201, second contact electrode 202, and third contact electrode 203 are arranged so as to protrude slightly from the side wall (bottom surface) of socket 204.

[0119] The first contact electrode 201 is disposed at a position where it comes into contact with the input terminal 111 when the signal responsive medium 1 is inserted into the socket 204 .

[0120] 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 .

[0121] The third contact electrode 203 is disposed at a position where it comes into contact with the output terminal 131 when the signal responsive medium 1 is inserted into the socket 204 .

[0122] As shown in Figure 12, when the signal responsive 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 responsive medium 1 and the reader 2.

[0123] 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.

[0124] 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 conversion 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 conversion unit 23, and a display unit 26 that displays the related information read out by the reading unit 24.

[0125] In the reader 2, at least the transmission unit 21 is grounded, so that the ground terminal 121 is grounded via the transmission unit 21, enabling the signal processing unit 12 to generate a response signal.

[0126] The converter 23 performs a Fourier transform on the multiple response signals transmitted from the receiver 22 to extract (generate) information on the center frequency, and generates a code by determining whether or not there is a correspondence between all the discrete frequency information and the extracted center frequency. The converter 23 can also identify (generate) information on the center frequency 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 the peak that appears in the response signal received by the receiver 22, and generate a code by determining whether or not there is a correspondence between all the discrete frequency information and the extracted or identified center frequency information. Thus, the converter 23 can identify the number of response signals and the center frequency of each response signal in the frequency domain and / or the time domain.

[0127] The memory unit 25 stores relevant 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.

[0128] 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.

[0129] 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).

[0130] [Code reading system according to the 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 a case where the reader 2 collates the signal response medium 1 in the code reading system of the second embodiment. Fig. 17 is a block diagram of the code reading system of the second embodiment.

[0131] 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 type code reading system.

[0132] 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), wristband type (Figures 23 and 24), tag type (Figures 25 and 26), label type (Figures 27 and 28), etc.

[0133] Furthermore, the reader 2 may have a shape having an upper surface (the surface that forms the outer shape of the reader 2 when viewed in a plane) facing the signal response medium 1 (Figures 15, 16, 18, 19, and 22).

[0134] As shown in Fig. 15, the card-type signal response medium 1 has a mounting section 15 that forms its outer shape. A first receiving antenna 112 and a first transmitting antenna 133 are disposed so as to face both main surfaces (surfaces that form the outer shape when the mounting section 15 is viewed in a plan view) of the mounting section 15. The first receiving antenna 112 and the first transmitting antenna 133 are disposed at different positions on both main surfaces.

[0135] 15, the second transmitting antenna 213 and the second receiving antenna 221 are disposed adjacent to the upper 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 or approximately the same as the distance between the first receiving antenna 112 (center) and the first transmitting antenna 133 (center).

[0136] As shown in Figure 16, by holding the signal responsive medium 1 over (positioning close to) the reader 2 so that the first receiving antenna 112 of the signal responsive medium 1 faces the second transmitting antenna 213 of the reader 2 and the first transmitting antenna 133 of the signal responsive medium 1 faces the second receiving antenna 221 of the reader 2, communication between the signal responsive medium 1 and the reader 2 becomes possible.

[0137] 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).

[0138] 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.

[0139] The signal generating unit 211, the converting unit 23, the reading unit 24, the storage unit 25, and the display unit 26 may be arranged in an external device (not shown) outside the reader 2 (housing).

[0140] In the reader 2, the signal generating unit 211 generates a chirp signal or an AC signal different from a chirp signal.

[0141] The second transmitting antenna 213 transmits the chirp signal or an AC signal different from the chirp signal as a radio wave toward the signal response medium 1 .

[0142] 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 to the signal processing unit 12 as a radio wave.

[0143] The first transmitting antenna 133 transmits the response signal to the reader 2 as a radio wave.

[0144] 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 .

[0145] In the signal-responsive medium 1, the voltage generating circuit 14 is connected to the input section 11 in parallel with the signal processing section 12.

[0146] 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.

[0147] 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 transmitting unit 21 (signal generating unit 211) and stores electric charge in a capacitor. As a result, the signal processing unit 12 (resistors R1, R2, 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.

[0148] In response to 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. In addition, when a charge is stored in the capacitor of the voltage generating circuit 14 by the chirp signal, the lowest discrete frequency (f 1 ) to 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 frequency limit (fH ), the lower limit frequency (f L ) to discrete frequencies (f 1 ) may be configured to store electric charge in the capacitor of the voltage generating circuit 14 by an AC signal of up to 1000 V. The DC voltage generated by the voltage generating circuit 14 is supplied to a capacitor constituting the voltage generating circuit 14, and the capacitor smoothes the DC voltage to stabilize the level of the response signal.

[0149] For communication between the signal responsive medium 1 and the reader 2, a radio wave method (radiated electromagnetic field method) is applied, but a wideband antenna is used to cover the frequency bandwidth of the chirp signal.

[0150] The frequency bands for chirp signals (radio waves) are UHF, VHF, and microwave.

[0151] 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 band.

[0152] [Modification of the second embodiment] Fig. 18 shows a modified example 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, the second transmitting antennas 213 and the second receiving antennas 221 are arranged alternately (staggered) in the X direction and the Y direction on the upper surface of the reader 2.

[0153] In FIG. 18, one second transmitting antenna 213 and one second receiving antenna 221 are arranged next to each other in the X direction, and the second transmitting antennas 213 and the second receiving antennas 221 are arranged alternately in the Y direction, but the second transmitting antennas 213 and the second receiving antennas 221 may also be arranged alternately in the X direction.

[0154] 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.

[0155] 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 arranged in the X direction (short side direction) in the signal response medium 1. Therefore, it is preferable to arrange them so that at least the interval 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 interval between the first receiving antenna 112 and the first transmitting antenna 133 of the signal response medium 1.

[0156] Corresponding to the configuration shown in FIG. 18, the second transmitting antennas 213 are connected in parallel to the signal generating unit 211 (FIG. 17), and the second receiving antennas 221 are connected in parallel to the converting unit 23 (FIG. 17).

[0157] In the arrangement shown in Figure 18, when the first receiving antenna 112 of the signal responsive medium 1 is positioned opposite one of the second transmitting antennas 213 of the reader 2, communication between the signal responsive medium 1 and the reader 2 becomes possible when the first transmitting antenna 133 of the signal responsive medium 1 is positioned opposite the second receiving antenna 221 adjacent to the second transmitting antenna 213 of the reader 2.

[0158] [Code reading system according to the third embodiment] Fig. 19 is a block diagram of the code reading system of the third embodiment, and Fig. 20 is a schematic diagram of a reader 2 constituting the code reading system of the third embodiment.

[0159] In the code reading system of the third embodiment, the signal responsive medium 1 is similar to that of the second embodiment (FIGS. 15 and 16).

[0160] 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).

[0161] As shown in FIG. 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 conversion unit 23 is connected to the second transmission / reception antenna 27B and insulated from the first transmission / reception antenna 27A, and the signal generation unit 211 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).

[0162] Therefore, when the first transmission / reception antenna 27A functions as a transmitting antenna, the second transmission / reception antenna 27B functions as a receiving antenna, and when the first transmission / reception antenna 27A functions as a receiving antenna, the second transmission / reception antenna 27B functions as a transmitting antenna.

[0163] 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, also in the third embodiment, it is preferable to arrange 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 so that at least the spacing in 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.

[0164] In Figure 20, when the first receiving antenna 112 of the signal response medium 1 is positioned adjacent to a position facing one of the first transmitting / receiving antennas 27A, the first transmitting antenna 133 of the signal response medium 1 is positioned adjacent 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 is possible between the signal response medium 1 and the reader 2.

[0165] Also, in Figure 20, when the first receiving antenna 112 of the signal response medium 1 is positioned adjacent to a position facing one of the second transmitting / receiving antennas 27B, the first transmitting antenna 133 of the signal response medium 1 is positioned adjacent 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 is possible between the signal response medium 1 and the reader 2.

[0166] 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.

[0167] [Code reading system according to a modified example of the third embodiment] Fig. 21 is a schematic diagram of a signal response medium 1 (key holder type) constituting a code reading system of a modified example of the third embodiment. Fig. 22 is a schematic diagram of a reader 2 constituting a code reading system of a modified example of the third embodiment.

[0168] As shown in FIG. 21, the signal response medium 1 (mounting portion 15) is a key holder (pendant) type, but its function is similar to that of the signal response medium 1 (card type) of the second embodiment (FIG. 16).

[0169] The key holder (pendant) type signal response medium 1 (mounting portion 15) has a mounting portion 15 that forms its outer shape. The mounting portion 15 has a circular central portion 151 and a frame portion 152 that has a shape that goes around the outer periphery of the central portion 151 and is a combination of a shape that follows a part (semicircle) of the outer shape of the central portion 151 and a tapered shape, and has a through hole 1521 in the tapered portion. The signal response medium 1 also includes a first ring 153 that is inserted into the through hole 1521 to be coupled to the frame portion 152, and a second ring 154 that is inserted into the first ring 153 to be coupled to the first ring 153. The first receiving antenna 112 and the first transmitting antenna 133 are arranged, for example, inside the central portion 151.

[0170] 22, in the reader 2, for example, one first transmitting / receiving antenna 27A is arranged, and a plurality of second transmitting / receiving antennas 27B are arranged so as to circle the periphery of the first transmitting / receiving antenna 27A. Note that, even in the modified example of the third embodiment, it is preferable to arrange 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) arranged around the first transmitting / receiving antenna 27A so that the distance between them 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.

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

[0172] 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 adjacent 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 adjacent to one of the second transmitting / receiving antennas 27B of the reader 2, communication is possible between the signal response medium 1 and the reader 2 when the connection state of the switching unit 28 is in the second connection state.

[0173] 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 each other 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 specifies the identification number of the signal-responsive medium 1 by determining whether there is a correspondence between all the discrete frequency information and the extracted center frequency information.

[0174] Furthermore, with regard to the second and third embodiments, the signal responsive 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 performs identification number identification.

[0175] [Wristband 4 equipped with signal response medium 1] Fig. 23 is a schematic diagram of a wristband 4 equipped with a signal response medium 1. Fig. 24 is a schematic diagram showing an example in which the wristband 4 equipped with the signal response medium 1 is wound in a roll shape.

[0176] 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 an end part in the longitudinal direction 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).

[0177] 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, which is then worn on the wrist. The adhesive portion 411 can be attached to any position on the surface of the band portion 41, so that the ring diameter can be adjusted as desired.

[0178] As shown in Fig. 24, the base material of the wristband 4 is a continuous body S1 wound in a roll. A perforation M1 for separation is formed in the continuous body S1 in accordance with the length of the band portion 41, and the signal response medium 1 (mounting portion 15) is attached adjacent to the perforation M1. Therefore, by cutting the continuous body S1 at the position of the perforation M1, the wristband 4 can be cut out from the continuous body S1.

[0179] [Tag 5 equipped with signal response medium 1] Fig. 25 is a schematic diagram showing the state of the tag 5 with the signal response medium 1 mounted thereon before it is cut off. Fig. 26 is a schematic diagram showing the state of the tag 5 with the signal response medium 1 mounted thereon after it is cut off.

[0180] 24 and 25, tag 5 includes mount 51 and sheet-like signal response medium 1 (mounting section 15) attached to the surface of mount 51. Mounting section 15 is made of plastic or the like, similar to that applied to wristband 4, but is formed in a freely deformable sheet shape.

[0181] The base material of the tag 5 is a continuous body S2, on which perforations M2 are formed to match the length of the mount 51. A sheet-like signal response medium 1 (mounting portion 15) is attached to the continuous body S2 at a position between a pair of adjacent perforations M2. The continuous body S2 is wound into a roll with the signal response medium 1 attached.

[0182] 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.

[0183] [Label-type signal response medium 1] Fig. 27 is a schematic diagram showing the state before the label-type signal response medium 1 is peeled off from the mount 52. Fig. 28 is a schematic diagram showing the state after the label-type signal response medium 1 is peeled off from the mount 52.

[0184] 27, the signal-responsive medium 1 (mounting portion 15) is a label formed in a sheet shape. The mounting portion 15 may be, for example, the same as that applied to 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 by an adhesive (not shown). The backing sheet 52 is wound in a roll shape with the signal-responsive medium 1 attached, similar to the continuum S2.

[0185] As shown in Figure 28, the signal-responsive medium 1 can be removed from the backing paper 52 by directly peeling it off from the backing paper 52, and the label-type signal-responsive medium 1 can be directly attached to the object using an adhesive (not shown).

[0186] [Effects of this embodiment] The signal responsive medium 1 of this embodiment includes an input section 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 section 12 that generates a plurality of response signals related to different center frequencies when the oscillation signal (chirp signal) is input to the circuit (parallel circuit) via the input section 11, and an output section 13 that outputs the response signals.

[0187] With the above configuration, an oscillation signal is input simultaneously to all bandpass filters (BPF1, BPF2, BPF3), and each bandpass filter selectively passes different frequencies, generating multiple response signals that have passed through each bandpass filter at different times. Therefore, a response signal that has passed through one bandpass filter is generated without being affected by other bandpass filters, and the response signals that have passed through each bandpass filter do not overlap in time, so that deterioration of the response signal in the frequency direction and time direction can be suppressed. Therefore, deterioration of the S / N ratio of the response signal in the frequency direction and time direction can be suppressed.

[0188] 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.

[0189] 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.

[0190] 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.

[0191] With the above configuration, it is possible to easily generate a response signal using a plurality of bandpass filters (BPF1, BPF2, BPF3).

[0192] In this embodiment, the multiple bandpass filters (BPF1, BPF2, BPF3) have different resonant frequencies (f 1 , f 2 , f 3 ) that selectively passes a response signal having a center frequency at the resonant frequency among the oscillation signals (chirp signals).

[0193] With the above configuration, a bandpass filter with a high Q value can be constructed, 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. In addition, an anti-resonant state appears in a parallel circuit of two bandpass filters with different resonant frequencies, and the anti-resonant frequency appears between the two resonant frequencies. As a result, a dip related to the anti-resonant frequency appears between the two response signals in the frequency domain, making it possible to separate the two response signals even more clearly in the frequency and time domains.

[0194] In this embodiment, the signal processing unit 12 further includes a voltage generating 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 generating circuit 14.

[0195] With the above configuration, a response signal can be generated stably even if the signal responsive medium 1 is not configured to be grounded to the outside.

[0196] In this embodiment, the device further includes a mounting portion 15 on which the input section 11, the signal processing section 12, and the output section 13 are mounted, and the input section 11 and the output section 13 include antennas (first receiving antenna 112, first transmitting antenna 133) arranged on the main surface of the mounting portion 15.

[0197] With the above configuration, a non-contact type signal response medium 1 can be easily constructed.

[0198] In this embodiment, the antenna includes a first receiving antenna 112 constituting the input section 11 and a first transmitting antenna 133 constituting the output section 13, and the first receiving antenna 112 and the first transmitting antenna 133 are arranged at different positions from each other on the main surface of the mounting section 15.

[0199] With the above configuration, in reader 2 which transmits an oscillation signal (chirp signal) to signal responsive medium 1 and receives a response signal from signal responsive medium 1, interference between the oscillation signal (chirp signal) and the response signal can be reduced.

[0200] 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.

[0201] With the above-mentioned configuration, wireless communication using radio waves between the signal response medium 1 and the reader 2 can be performed with a simple configuration.

[0202] In this embodiment, the frequency band of the radio waves is the UHF band.

[0203] With the above configuration, by using radio waves in the UHF band, it is possible to extend the communication distance and to read a plurality of signal response media 1 at once.

[0204] 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 that order, with the open end of the inductor L connected to the input section 11 and the midpoint of the connection between the capacitor C and the resistor R connected to the output section 13.

[0205] With the above configuration, a bandpass filter can be constructed with a simple structure.

[0206] In this embodiment, the series circuit is composed of a lumped constant circuit and / or a distributed constant circuit.

[0207] The above configuration allows for greater variety in the creation of the impedance elements (inductor L, capacitor C, resistor R) that make up the series circuit. In particular, when the series circuit is constructed entirely from distributed constant circuits, the entire circuit can be made compact, increasing the information density per unit area (DPS). In addition, a bandpass filter with a high Q value can be constructed using distributed constant circuits, increasing the information density per unit frequency (DPF).

[0208] In this embodiment, the device further includes a mounting portion 15 on which the input section 11 (input terminal 111), the signal processing portion 12, and the 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, the output terminal 131, and the ground terminal 121 are arranged at different positions on the mounting portion 15.

[0209] With the above configuration, the contact-type signal response medium 1 can be easily constructed.

[0210] 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.

[0211] With the above configuration, the signal response medium 1 can be applied in a wide range.

[0212] The code detection system of the present 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 1 bit, and a code having the number of bits of the information is set as an 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 a 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 be 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.

[0213] With the above configuration, it is possible to identify as a code the identification number set in the signal response medium 1. Also, by appropriately setting the number of discrete frequencies and the number of bandpass filters, it is possible to set codes and identification numbers with a large amount of information.

[0214] The signal-responsive medium identification system of the present invention includes a signal-responsive medium 1, and a plurality of discrete frequencies different from each other are set in a frequency band (of a chirp signal) and a center frequency is set to one of the discrete frequencies, thereby setting an identification number of the signal-responsive medium 1 by a combination of signal components of the center frequencies 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 determining the identification number.

[0215] The above configuration makes it possible to easily identify the identification number set in the signal response medium 1. In addition, by appropriately setting the number of discrete frequencies and the number of bandpass filters, it is possible to set an identification number with a large amount of information.

[0216] In this embodiment, it 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.

[0217] With the above configuration, communication between the signal responsive medium 1 and the reader 2 can be carried out in a non-contact manner.

[0218] The code detection system according to the present 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 on the presence or absence of a signal component of each discrete frequency in a response signal is set as 1 bit, and a code having the number of bits of such information is set as an identification number of the signal-responsive medium 1. The code detection system includes a reader 2 for contacting the signal-responsive medium 1 to transmit an oscillation signal (chirp signal) to the signal-responsive medium 1 and for receiving a response signal from the signal-responsive medium 1, a transmitting unit 21 (first contact electrode 201) in the reader 2, which is disposed at a position where it contacts an input terminal 111 when the signal-responsive medium 1 contacts the reader 2, and transmits the oscillation signal (chirp signal) to the input terminal 111, and a receiving unit 22 (third contact electrode 203) that is arranged in a position to contact the output terminal 131 when the ground terminal 121 contacts the ground portion (second contact electrode 202) in the reader 2 and receives a response signal transmitted from the output terminal 131 when the ground terminal 121 contacts the ground portion (second contact electrode 202) in the reader 2; and a conversion unit 23 that converts the response signal into a code. 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 , f2 , f 3 ) are individually set to be 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.

[0219] With the above configuration, it is possible to identify as a code the identification number set in the signal response medium 1. Also, by appropriately setting the number of discrete frequencies and the number of bandpass 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.

[0220] 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 of the discrete frequencies and the extracted or identified information about the center frequency.

[0221] With the above configuration, the number of response signals and the discrete frequencies of the response signals can be detected with high accuracy.

[0222] The code detection system of this embodiment includes a (non-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 on the presence or absence of a signal component of each discrete frequency in a 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 an identification number of the signal-responsive medium 1. The code detection system includes a reader 2 which is disposed adjacent to the signal-responsive medium 1 while facing the main surface of the signal-responsive medium 1 and 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 which 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 arranged opposite the first receiving antenna 112 and transmitting radio waves related to an oscillation signal (chirp signal) to the first receiving antenna 112; a second receiving antenna 221 arranged opposite the first transmitting antenna 133 when the first receiving antenna 112 is arranged close to the second transmitting antenna 213 in the reader 2 and receiving radio waves related to a response signal transmitted from the first transmitting antenna 133; and a conversion unit 23 converting 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 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 be 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.

[0223] With the above configuration, it is possible to identify the identification number set in the signal response medium 1 as a code. Also, by appropriately setting the number of discrete frequencies and the number of bandpass filters, it is possible to set a code and identification number with a large amount of information, and the code can be detected through communication via electromagnetic waves.

[0224] In this embodiment, the mounting unit 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 unit 15, the first transmitting antenna 133 can transmit a response signal from both main surfaces of the mounting unit 15, the second transmitting antennas 213 are connected in parallel to the signal generating unit 211, the second receiving antennas 221 are connected in parallel to the converting unit 23, and the multiple second transmitting antennas 213 and the multiple second receiving antennas 221 form a single second transmitting antenna in a first direction (X direction). The antenna 213 and one second receiving antenna 221 are arranged next to each other, 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 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).

[0225] With the above configuration, multiple possible arrangements of the reader 2 and the signal responsive medium 1 can be set when the reader 2 transmits an oscillation signal (chirp signal) to the signal responsive medium 1 and the signal responsive medium 1 transmits a response signal to the reader 2, making it easy to communicate between the reader 2 and the signal responsive medium 1.

[0226] The code reading system of this embodiment is a code detection system including a (non-contact type) signal responsive medium 1, in which a plurality of discrete frequencies having different frequencies from each other 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 is set as an identification number of the signal responsive medium 1. The code reading system includes a reader 2 in which the signal responsive medium 1 is disposed adjacent to the reader 2 while facing a main surface of the signal responsive medium 1 (mounting unit 15), 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 an 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 adjacent 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, and in the reader 2, the first transmitting / receiving antenna 27A is disposed adjacent to one of the first receiving antenna 112 and the first transmitting antenna 133. a second transmission / reception antenna 27B that is arranged at a position facing the other of the first reception antenna 112 and the first transmission antenna 133 when the antenna is placed in the first position and is capable of transmitting radio waves related to an oscillation signal (chirp signal) and receiving radio waves related to a response signal; a conversion unit 23 that converts the response signal into a code; 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; a switching unit 28 that executes switching control to alternate between a first connection state in which the signal generating unit 211 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 signal generating unit 211 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 be 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.

[0227] 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 upside down and close to the reader 2, even if communication between the signal response medium 1 and the reader 2 is impossible, communication becomes possible after a predetermined time has elapsed, so that the operational burden on the user who uses the signal response medium 1 can be reduced.

[0228] 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, the first transmitting / receiving antenna 27A and the second transmitting / receiving antenna 27B are arranged in multiple numbers so that one of them surrounds the other.

[0229] 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 being arbitrary, even if communication between the signal response medium 1 and the reader 2 is impossible, communication becomes possible after a predetermined time has elapsed, thereby reducing the operational burden on the user who uses the signal response medium 1.

[0230] The signal-responsive medium identification method of the present embodiment is a signal-responsive medium identification method for a signal-responsive medium 1 including an input unit 11 to which an oscillation signal (chirp signal) whose oscillation frequency changes over time in a predetermined frequency band is input, 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, and which generates a plurality of response signals related to 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 signal.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 1 by a combination of signal components of the center frequencies in the response signal, and the identification number is specified by extracting center frequency information from the response signal and determining whether there is a correspondence between all of the discrete frequency information and the extracted center frequency information.

[0231] The above method makes it possible to easily identify the identification number set in the signal response medium 1. In addition, by appropriately setting the number of discrete frequencies and the number of bandpass filters, it is possible to set an identification number with a large amount of information.

[0232] 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 changes over time in a predetermined frequency band is input, a circuit (parallel circuit) in which a plurality of band pass 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 related to different center frequencies by inputting the oscillation signal (chirp signal) to the circuit (parallel circuit) via the input unit 11, and an output unit 13 that outputs the response signals, wherein a plurality of discrete frequencies different from each other in frequency are set in the frequency band, and a code in which information on the presence or absence of a signal component of each discrete frequency in the response signal is one bit and the number of pieces of information is the number of bits is an identification number of the signal-responsive medium 1. A code detection method for detecting a code on a signal-responsive medium 1 when the number of bandpass filters (BPF1, BPF2, BPF3) in the signal-responsive medium 1 is set corresponding to the number of discrete frequencies corresponding to the identification number, and the center frequencies of the bandpass filters (BPF1, BPF2, BPF3) are individually set to be mutually different discrete frequencies so that the code becomes a code corresponding to the identification number, the code detection method includes 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 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 center frequency information.

[0233] By using the above method, it is possible to identify as a code the identification number set in the signal response medium 1. In addition, by appropriately setting the number of discrete frequencies and the number of bandpass filters, it is possible to set codes and identification numbers with a large amount of information.

[0234] In this embodiment, in the transmission step, the lowest frequency (lower limit frequency (f L ) to the highest frequency (upper limit frequency (f H)), and in a conversion step, the response signal is subjected to a Fourier transform to extract center frequency information, 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 a code by determining whether or not there is a correspondence between all of the discrete frequency information and the extracted or identified center frequency information.

[0235] By using the above method, the number of response signals and the discrete frequencies of the response signals can be detected with high accuracy.

[0236] An embodiment of the present invention has been described above, but the above embodiment merely illustrates 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. [Explanation of symbols]

[0237] 1 Signal response medium 111 Input terminal 112 Input section Rx1 Receiving antenna 12 Signal Processing Section BPF1, BPF2, BPF3 Bandpass Filters 121 Ground terminal 131 Output terminal 132 Output section Tx1 Transmitting Antenna 14 Voltage Generation Circuit 15 Mounting section 2. Leader 201 Outlet 21 Transmitter 211 1st contact electrode 212 2nd contact electrode 213 Third contact electrode Tx2 Transmitting Antenna 22 Receiving section Rx2 receiving antenna 23 Conversion section 24 Reading section 25 Memory section 26 Display section 27A Transmitting and receiving antenna 27B Transmitting and receiving antenna 28 Switching section 31 Ground plate 32 Printed Circuit Board 33 Microstrip Line 34 First microstrip line 35 Second microstrip line 36 Cuboid 4 Wristbands S1 Continuum M1 Perforation 41 Band Club 411 Adhesive part 5 Tags S2 Continuum M2 Perforation 51 Mount 52 Mount

Claims

1. an input section to which an oscillation signal whose oscillation frequency changes over time in a predetermined frequency band is input; a signal processing unit including a circuit in which a plurality of band pass filters are connected in parallel, each of which selectively passes signals having center frequencies different from each other in the frequency band, and which generates a plurality of response signals relating to the center frequencies different from each other by inputting the oscillation signal to the circuit via the input unit; and an output section that outputs the response signal.

2. 2. The signal responsive medium according to claim 1, 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 portion, and the other of the pair of ends is connected to the output portion.

3. the oscillation signal is a chirp signal whose oscillation frequency is swept in the frequency band, The signal responsive medium of claim 1 , wherein the signal processing unit generates the response signal from the chirp signal.

4. The plurality of band pass filters are resonant circuits having mutually different resonant frequencies, 2. The signal responsive medium according to claim 1, which selectively passes the response signal having the resonant frequency as the center frequency of the oscillation signal.

5. 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; The signal responsive medium according to claim 1 , wherein the signal processing unit is capable of generating the response signal based on the DC voltage of the voltage generating circuit.

6. The input unit, the signal processing unit, and the output unit are mounted on a mounting unit.

2. The signal responsive medium of claim 1, wherein the input portion and the output portion include antennas disposed on a major surface of the mounting portion.

7. The antenna includes a first receiving antenna constituting the input section and a first transmitting antenna constituting the output section, 7. The signal responsive medium according to claim 6, wherein the first receiving antenna and the first transmitting antenna are arranged at different positions on a main surface of the mounting portion.

8. In the case where the oscillation signal is transmitted as a radio wave, the first receiving antenna is capable of receiving the radio wave and transmitting the oscillation signal to the signal processing unit; The signal responsive medium according to claim 7 , wherein the first transmitting antenna is capable of transmitting the response signal as the radio wave.

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

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

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

12. The input unit, the signal processing unit, and the output unit are mounted on a mounting unit. an input terminal constituting the input section, an output terminal constituting the output section, and a ground terminal connected to an open end of the resistor are arranged on the mounting section; 11. The signal-responsive medium according to claim 10, wherein the input terminal, the output terminal and the ground terminal are arranged at different positions on the mounting portion.

13. 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. 2. A signal responsive medium identification system including the signal responsive medium according to claim 1, wherein 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 the center frequency in the response signal, A signal responsive medium identification system that extracts the center frequency information from the response signal and identifies the identification number by determining whether there is a correspondence between the information of all of the discrete frequencies and the extracted center frequency information.

15. a reader for transmitting the oscillating signal to the signal responsive medium; the signal responsive medium transmits the response signal to the reader; 15. The signal responsive medium identification system of claim 14, wherein the reader receives the response signal.

16. 2. A code detection system including the signal response medium according to claim 1, wherein a plurality of discrete frequencies different from each other 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 set as 1 bit, and a code having the number of bits of the information is set as an identification number of the signal response medium, a transmitter that transmits the oscillation signal to the input unit; a receiving unit that receives the response signal transmitted from the output unit; a conversion unit that converts the response signal into the code, In the signal responsive medium, the number of the band pass filters is set in accordance with the number of signals of the discrete frequency corresponding to the identification number, and the center frequencies of the band pass filters are individually set to be the discrete frequencies different from one another; 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.

17. A code detection system including the signal response medium according to claim 12, wherein a plurality of discrete frequencies different from each other 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 set as 1 bit, and a code having the number of bits of the information is set as an identification number of the signal response medium, a reader for contacting the signal responsive medium to transmit the oscillating signal to the signal responsive medium and to receive the response signal from the signal responsive medium; a transmitter arranged in the reader at a position where the transmitter comes into contact with the input terminal when the signal response medium comes into contact with the reader, the transmitter transmitting the oscillation signal to the input terminal; a grounding portion electrically connected to the transmitting portion and disposed in the reader at a position where the grounding portion comes into contact with the grounding terminal when the input terminal comes into contact with the transmitting portion; a receiving unit disposed in the reader at a position where the receiving unit contacts the output terminal when the ground terminal contacts the ground portion, the receiving unit receiving the response signal transmitted from the output terminal; a conversion unit that converts the response signal into the code, In the signal responsive medium, The number of the band-pass filters is set in accordance with the number of signals of the discrete frequency 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. the signal processing unit is grounded via the ground unit, thereby enabling the response signal to be generated from the oscillation signal; 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.

18. the transmission unit changes a frequency of the oscillation signal so as to sweep from a lowest frequency to a highest frequency in the frequency band; 18. The code detection system according to claim 16 or 17, wherein the conversion 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 by identifying information of the center frequency of the response signal based on a timing of the response signal received by the receiving unit, and 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.

19. 10. A code detection system including the signal response medium according to claim 8 or 9, 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 set as 1 bit, and a code having the number of bits of the information is set as an identification number of the signal response medium, a reader disposed adjacent to the signal-responsive medium and facing a main surface of 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 disposed in the reader at a position facing the first receiving antenna when the signal response medium is disposed in proximity to the reader, the second transmitting antenna transmitting the radio wave related to the oscillation signal to the first receiving antenna; a second receiving antenna disposed in the reader at a position facing the first transmitting antenna when the first receiving antenna is disposed close to the second transmitting antenna, the second receiving antenna receiving the radio wave associated with the response signal transmitted from the first transmitting antenna; a conversion unit that converts the response signal into the code, In the signal responsive medium, the number of the band pass filters is set in accordance with the number of signals of the discrete frequency corresponding to the identification number, and the center frequencies of the band pass filters are individually set to be the discrete frequencies different from one another; 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.

20. 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 antenna is connected in parallel to the signal generating unit. The second receiving antenna is connected in parallel to the converter. The plurality of second transmitting antennas and the plurality of second receiving antennas include One of the second transmitting antennas and one of the second receiving antennas are arranged side by side in a first direction, and the second transmitting antennas and the second receiving antennas are arranged alternately in a second direction perpendicular to the first direction, 20. The code detection system according to claim 19, wherein the distance between the second transmitting antenna and the second receiving antenna arranged in the first direction is the same as the distance between the first receiving antenna and the first transmitting antenna.

21. 10. A code detection system including the signal response medium according to claim 8 or 9, 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 set as 1 bit, and a code having the number of bits of the information is set as an identification number of the signal response medium, a reader disposed adjacent to the signal-responsive medium and facing a main surface of 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 first transmitting / receiving antenna arranged in a position facing one of the first receiving antenna and the first transmitting antenna when the signal response medium is placed in close proximity to the reader, the first transmitting 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 transmission / reception antenna arranged in a position facing the other of the first reception antenna and the first transmission antenna when the first transmission / reception antenna is arranged adjacent to one of the first reception antenna and the first transmission antenna in the reader, the second transmission / reception 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; 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 transmission / reception antenna and insulated from the second transmission / reception antenna and the conversion unit is connected to the second transmission / reception antenna and insulated from the first transmission / reception antenna, and a second connection state in which the conversion unit is connected to the second transmission / reception antenna and insulated from the first transmission / reception antenna and the signal generation unit is connected to the first transmission / reception antenna and insulated from the second transmission / reception antenna; Including, In the signal responsive medium, the number of the band pass filters is set in accordance with the number of signals of the discrete frequency corresponding to the identification number, and the center frequencies of the band pass filters are individually set to be the discrete frequencies different from one another; 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. 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; 22. The code detection system according to claim 21, wherein in the reader, either the first transmitting / receiving antenna or the second transmitting / receiving antenna is disposed in plurality so as to surround the other.

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

24. a signal processing unit that generates a plurality of response signals related to the mutually different center frequencies by inputting the oscillation signal to the circuit via the input unit, and an output unit that outputs the response signals, wherein a plurality of discrete frequencies different from each other 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 the information as a number of bits is an identification number of the signal-responsive medium, 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, and the center frequencies of the band-pass filters are individually set to be the mutually different discrete frequencies, a transmitting step of transmitting the oscillating signal to the signal responsive medium; a receiving step of receiving the response signal transmitted from the signal responsive medium; and 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. In the transmitting step, a frequency of the oscillation signal is changed so as to sweep from a lowest frequency to a highest frequency in the frequency band; 25. The code detection method according to claim 24, wherein in the converting step, the response signal is converted into the code by subjecting the response signal to a Fourier transform to extract information of the center frequency, or identifying the information of the center frequency of the response signal based on a timing of receiving the response signal, and 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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