JP7552099B2 - Antenna device and antenna device card - Google Patents

Description

The present invention relates to an antenna device equipped with an antenna circuit, in particular an antenna device and an antenna device card that can select and switch between multiple antennas to use an appropriate one.

Conventionally, IC tags and cards are known as antenna devices equipped with antenna circuits capable of transmitting and receiving information and generating power via electromagnetic waves of a specific frequency. In particular, cards that are antenna devices capable of transmitting and receiving information via electromagnetic waves are also called non-contact IC cards, and many are in use that comply with, for example, ISO/IEC 14443 or NFC communication standards. Antenna devices and cards capable of transmitting and receiving information via electromagnetic waves are broadly divided into passive types that do not have their own power source and operate using the electromotive force of electromagnetic induction when the antenna circuit receives electromagnetic waves transmitted from an external device, and active types that have an internal power source such as a secondary battery and can operate even if they are not receiving electromagnetic waves from an external device. Note that many active non-contact IC cards are of the type that store electricity generated by the electromotive force of electromagnetic induction due to electromagnetic waves from an external device in a power source.

In addition, from the perspective of strengthening authentication of users of antenna devices, these antenna devices are required to be equipped with biometric sensors such as fingerprint authentication, and to enable information transmission and reception via the antenna circuit only when the user has been authenticated as a legitimate user, thereby preventing unauthorized use such as skimming, and to be equipped with display devices such as liquid crystal or electronic paper, so that the status of the antenna device can be clearly determined by the user. However, these biometric sensors and display devices generally consume a large amount of power to operate, and if power is supplied without any control, there is a possibility that operation will be interrupted due to a lack of power in the middle of transmitting and receiving information via the antenna or biometric authentication. Furthermore, an interruption in operation while reading data from or writing data to memory may cause the IC chip that drives the antenna device to malfunction or break down.

For example, Patent Document 1 describes a fingerprint recognition card that includes a first area having a card control unit that transmits power provided by a built-in battery to a second area equipped with a fingerprint sensor etc. in response to input from the power button, and connects an antenna in a third area based on the fingerprint authentication result to control activation of the communication function, a second area that is activated in response to power supplied from the first area and is equipped with a fingerprint recognition sensor that detects a fingerprint input by the holder, and a third area that is activated based on the control of the first area.

Patent Document 2 also describes a circuit that includes an antenna having a first pair of terminals and a second pair of terminals, in which at least one of the second pair of terminals is connected to the antenna between the first pair of terminals so that the voltage generated by the second pair of terminals is lower than the voltage generated by the first pair of terminals when an RF signal is received by the antenna, and that in a first operation mode in which power is supplied only to a fingerprint scanner or the like, the voltage generated by the first pair of terminals is used, and in a second operation mode in which communication is performed with an RFID scanner, the voltage generated by the second pair of terminals is used to supply power to the fingerprint scanner or the like.

On the other hand, Patent Document 3 describes a rechargeable contactless IC card system that uses separate antenna coils to receive and detect the AC magnetic field generated by an identification device, which has two different dedicated frequencies: one that can be used by the identification device and a contactless IC card to send and receive data, and another that can allow the contactless IC card to obtain power to charge a rechargeable battery.

JP 2019-160304 A Special table 2017-532706 publication Japanese Patent Application Publication No. 10-307898

In general, when an antenna device is used for different purposes, such as a communication antenna and a charging antenna, it is more advantageous to configure each antenna to function at the same frequency. This is because the external device, such as a reader, can be designed to transmit and receive signals at only a single frequency, simplifying the device configuration. However, when using the same antenna for different purposes, it is generally difficult to completely electrically separate the antenna circuit when used for one purpose from the antenna circuit when used for another purpose, and it is possible that the influence of fluctuations in voltage and current of an antenna used for one purpose may extend to the antenna circuit used for other purposes that are not intended for use. For example, noise input when used as a charging antenna may be erroneously determined to be input from a communication antenna. On the other hand, if a communication antenna and a charging antenna that function at the same frequency are provided separately, there is a risk that the communications between them will interfere with each other, resulting in neither communication nor charging functions being performed well.

This disclosure has been made in light of these circumstances, and aims to provide an antenna device and an antenna device card that can smoothly switch to an appropriate antenna depending on the application.

The antenna device according to the present embodiment includes a first circuit having a first IC chip, a first antenna capable of forming a closed circuit by electrically connecting with the first IC chip, and a first switch circuit capable of switching between a first mode and a second mode, which is arranged in series or parallel to the closed circuit formed by the first IC chip and the first antenna; and a third circuit having a second IC chip, a second antenna capable of forming a closed circuit by electrically connecting with the second IC chip, and a third switch circuit arranged in series or parallel to the closed circuit formed by the second IC chip and the second antenna. and a second circuit having a second switch circuit that can be switched to a first mode or a fourth mode, in which the first circuit resonates with electromagnetic waves of a predetermined frequency in the first mode and does not resonate in the second mode, the second circuit resonates with electromagnetic waves of the predetermined frequency in the third mode and does not resonate in the fourth mode, and when the first switch circuit is in the second mode, the second switch circuit can be switched to the third mode, and when the second switch circuit is in the fourth mode, the first switch circuit can be switched to the first mode.

In addition, in an antenna device according to another embodiment of the present invention, at least one of the first switch circuit and the second switch circuit may have a switch and a capacitive element electrically connected in series, and the switch circuit may be arranged in parallel with the corresponding closed circuit.

In another embodiment of the antenna device, the first switch circuit and the second switch circuit are both configured such that the switch and the capacitance element are electrically connected in series, and both switch circuits are arranged in parallel with the corresponding closed circuit, and the capacitance element of the first switch circuit and the capacitance element of the second switch circuit may have different capacitances.

Furthermore, in an antenna device according to another embodiment of the present invention, when the specified frequency is _f0 , the resonant frequency of the first circuit in the second mode is _f1 , and the resonant frequency of the second circuit in the fourth mode is _f2 , the value of _f1 / _f0 or _f2 / _f0 may be less than 0.9 or greater than 1.1.

In addition, in an antenna device according to another embodiment of the present invention, when the first circuit receives electromagnetic waves of the predetermined frequency, the absolute value of the induced voltage in the first mode is _V01 , the absolute value of the induced voltage in the second mode is _V1 , and when the second circuit receives electromagnetic waves of the predetermined frequency, the absolute value of the induced voltage in the third mode is _V02 , and the absolute value of the induced voltage in the fourth mode is _V2 , the value of _V1 / _V01 or _V2 / _V02 may be smaller than 0.5.

In addition, in an antenna device according to another embodiment of the present invention, at least one of the first switch circuit and the second switch circuit may have only a switch electrically connected thereto, a capacitance element may be arranged in parallel in the closed circuit corresponding to any one of the switch circuits, and any one of the switch circuits may be arranged in parallel to the capacitance element.

In addition, in an antenna device according to another embodiment of the present invention, if any of the switch circuits is the first switch circuit, the first circuit may be in the first mode when the switch of the first switch circuit is in the open state, and in the second mode when the switch is in the closed state; if any of the switch circuits is the second switch circuit, the second circuit may be in the third mode when the switch of the second switch circuit is in the open state, and in the fourth mode when the switch is in the closed state.

In addition, in an antenna device according to another embodiment of the present invention, at least one of the first switch circuit and the second switch circuit may be electrically connected to only a switch, and the switch circuit may be arranged in series with the closed circuit.

In addition, in an antenna device according to another embodiment of the present invention, if any of the switch circuits is the first switch circuit, the first circuit may be in the first mode when the switch of the first switch circuit is closed and in the second mode when the switch is open; if any of the switch circuits is the second switch circuit, the second circuit may be in the third mode when the switch of the second switch circuit is closed and in the fourth mode when the switch is open.

In another embodiment of the antenna device, the first circuit is capable of non-contact communication by transmitting and receiving electromagnetic waves of the predetermined frequency in the first mode, and the non-contact communication is difficult in the second mode, and the second circuit is capable of supplying a current generated by an electromotive force of electromagnetic induction by receiving electromagnetic waves of the predetermined frequency to the second IC chip, or to a power supply unit if a power supply unit is further provided, in the third mode, and the first circuit is maintained in the second mode when a predetermined condition is not satisfied, and when the predetermined condition is satisfied, the second circuit is switched from the third mode to the fourth mode, and the first circuit is switched from the second mode to the first mode.

In another embodiment of the antenna device, the antenna device may further include a power supply unit that is electrically connected to the first circuit and is capable of storing a current generated by an electromotive force of electromagnetic induction due to reception of electromagnetic waves of the predetermined frequency when the first circuit is in the first mode.

In addition, a card that is an antenna device according to another embodiment of the present invention may include one or more insulating substrates, the first circuit and the second circuit formed on one side of the substrate, a spacer adjacent to the one side of the substrate and having a through hole or a notch for protecting components of the first circuit and the second circuit, a first base material disposed on the opposite side of the spacer from the substrate, and a second base material adjacent to the other side of the substrate.

In addition, the card that is the antenna device according to another embodiment of this invention may be a dual interface type card that further includes an external contact terminal, and the first circuit is further capable of contact communication via the external contact terminal.

According to this embodiment, it is possible to provide an antenna device and a card that is an antenna device that can smoothly switch to an appropriate antenna depending on the application.

1 is a schematic plan view illustrating a configuration of an antenna device according to a first embodiment of the present disclosure. FIG. 2 is a cross-sectional view illustrating the configuration of the antenna device according to the first embodiment shown in FIG. 1 . FIG. 2 is a diagram illustrating a circuit of the antenna device according to the first embodiment. 1 is a block diagram showing a configuration of an antenna device according to a first embodiment; FIG. 4 is a flow chart illustrating the operation of the antenna device according to the first embodiment. FIG. 4 is a flow diagram illustrating the operation of the antenna device according to the first embodiment. 5A to 5C are diagrams illustrating a manufacturing process of the antenna device according to the first embodiment. 5A to 5C are diagrams illustrating a manufacturing process of the antenna device according to the first embodiment. FIG. 13 is a diagram showing a circuit of an antenna device according to a second embodiment of the present disclosure. FIG. 13 is a diagram showing a circuit of an antenna device according to a third embodiment of the present disclosure. 13 is a schematic plan view illustrating the configuration of an antenna device according to a fourth embodiment of the present disclosure. FIG. 11 is a cross-sectional view illustrating a configuration of an antenna device according to a third modified example. FIG. 13A to 13C are diagrams illustrating a manufacturing process of an antenna device according to Modification 3.

Below, an example of an antenna device and a card that is an antenna device according to the present disclosure will be described with reference to the drawings, etc. However, the antenna device and the card that is an antenna device according to the present disclosure are not limited to the embodiments and examples described below.

The figures shown below are schematic. Therefore, the size and shape of each part are appropriately exaggerated to make it easier to understand. In addition, hatching showing the cross section of a member is omitted as appropriate in each figure. The numerical values such as dimensions and material names of each member described in this specification are examples of embodiments, and are not limited to these, and may be selected as appropriate for use. In this specification, terms that specify shapes or geometric conditions, such as parallel, orthogonal, and perpendicular, are intended to include substantially the same state in addition to their strict meaning.

1. First embodiment of the present disclosure An example of a first embodiment of an antenna device of the present disclosure will be described. Fig. 1 is a plan view of an antenna device 1, which is a card, viewed from the normal direction of the main surface of the card. Fig. 2 is a cross-sectional view of a cross section cut along line A-A along the long side direction of the antenna device 1 that crosses the control chip 41, the power supply unit 6, and the biometric information sensor 5 in the plan view of the antenna device 1 in Fig. 1, viewed from the lower side of the paper. Fig. 3 is a diagram showing a schematic circuit of the antenna device, and Fig. 4 is a block diagram showing the configuration of the antenna device.

The antenna device 1 has a thin, so-called credit card shape with a roughly rectangular surface with arc-shaped corners on both sides. It is preferable that the antenna device 1 is sized to approximate the long side dimension of 85.6 mm and the short side dimension of 53.98 mm, which are compliant with the credit card standards ISO 7810 and ISO 7816-1. This is because the antenna device 1 can be used as a credit card and can be easily stored together with other cards in a pass case or the like. The circuit board 23 can be made slightly smaller than this to ensure a good overall finish. However, the thickness of the antenna device 1 does not necessarily have to be less than 0.84 mm, which is the maximum value of the standard. This is because the thickness of the antenna device 1 equipped with various components, which will be described later, usually exceeds the above thickness.

The antenna device 1 described in the first embodiment is card-shaped, but the shape of the antenna device 1 is not limited to this, and may be, for example, an IC tag also known as an RFID tag or electronic tag, a label-type device, a wearable terminal, a key chain-type device, or a structure incorporated inside other electronic devices.

As shown in FIG. 1, the antenna device 1 includes a substrate 2 that is substantially rectangular in shape, a substantially rectangular biometric sensor 5 that is disposed on the surface of the substrate 2, a display unit 7, and a power switch 8, all of which can be seen directly from outside the antenna device 1. The components shown in dashed lines are disposed inside or at the rear of the substrate 2 and therefore cannot be seen directly, but the antenna device 1 further includes an RF communication circuit 3 that includes an RF chip 31 and an RF antenna 32, and a control circuit 4 that includes a control chip 41, a control antenna 42, the biometric sensor 5, and a power supply unit 6.

The antenna device 1 receives electromagnetic waves of a specific frequency emitted from an external device such as a reader at the control antenna 42 of the control circuit 4, and stores the current generated by the electromotive force of electromagnetic induction in the power supply unit 6, supplies it to the control chip 41 via wiring 41c, and also supplies power from the control chip 41 to the biometric information sensor 5 via wiring 41e. This allows the control chip 41 and the biometric information sensor 5 to operate continuously. The user of the antenna device 1 places his or her finger on the biometric information sensor 5, which can be exemplified as a fingerprint sensor, to read his or her fingerprint information, and the control chip 41 determines whether or not the device is being used by a legitimate user by comparing it with previously registered information.

Furthermore, when the control chip 41 authenticates that the antenna device 1 is being used by a legitimate user, the control antenna 42 of the control circuit 4 is disabled and the RF antenna 32 of the RF communication circuit 3 is enabled in response to an instruction from the control unit of the control chip 41. This allows the antenna device 1 to receive electromagnetic waves of a specific frequency emitted from an external device such as a reader using the RF antenna 32 of the RF communication circuit 3, supply the current generated by the electromotive force of electromagnetic induction to the RF chip 31, and enable contactless communication between the external device and the RF communication circuit 3 by transmitting and receiving electromagnetic waves.

An electric circuit including an antenna to perform a certain function, such as the RF communication circuit 3 and the control circuit 4, is called an antenna circuit. In addition, the antenna is enabled when the antenna can perform its functions of transmitting and receiving electromagnetic waves and receiving power well so that the antenna circuit can perform its specified function, i.e., when the antenna can transmit and receive electromagnetic waves of a specified frequency and receive power, and the antenna is disabled when it cannot perform its function well, i.e., when it is difficult for the antenna to transmit and receive electromagnetic waves of a specified frequency and receive power, and the antenna is disabled. Furthermore, the antenna circuit and the function are activated when the antenna circuit can perform the specified function well, and the antenna circuit and the function are deactivated when the antenna circuit cannot perform the specified function well.

Here, the antenna device 1 is controlled to enable either the control antenna 42 of the control circuit 4 or the RF antenna 32 of the RF communication circuit 3, and disable the other, in response to an instruction from the control unit of the control chip 41. The control antenna 42 and the RF antenna 32 of the RF communication circuit 3 are enabled and disabled by switching the switches of the switch circuits provided in each antenna and reconnecting part of the circuit, as will be described in detail later.

The antenna device 1 can activate either the control antenna 42 or the RF antenna 32 and disable the other according to an instruction from the control chip 41. In this way, by activating either the biometric authentication function or the non-contact communication function, it is possible to avoid concentration of power consumption compared to, for example, activating both functions simultaneously, and to suppress adverse effects caused by a current flowing through one of the antennas in use flowing to the other unused antenna. In addition, there is no need to provide a special communication circuit or the like between the RF chip 31 and the control chip 41, and the RF chip 31 can be selected regardless of the function of the control chip 41, which expands the range of chip selection and simplifies circuit design. Below, each part of the main components of the antenna device 1 of the first embodiment will be described.

(a) RF communication circuit As shown in FIG. 1, the RF communication circuit 3 includes an RF chip 31 and an RF antenna 32, both ends of which are electrically connected to the RF chip 31. As shown in FIG. 2, the RF communication circuit 3 includes a circuit board 23 that supports the RF chip 31 and the RF antenna 32. As shown in FIG. 3, the RF communication circuit 3 includes a tuning capacitor 33 for matching the resonant frequency, a switch circuit 34 for switching a part of the circuit, a rectifier circuit 37 for rectifying the current generated by the electromotive force of electromagnetic induction of the RF antenna 32, and a field effect transistor 38 for generating an on/off signal for applying load modulation when sending reply data from the antenna device 1. The switch circuit 34 can enable or disable the RF antenna 32 depending on the open/close state of the internal switch 35. Note that open refers to the open state of the switch, and closed refers to the closed state of the switch.

The essential components of the RF communication circuit 3 are the RF antenna 32, the switch circuit 34, and the RF chip 31. With this configuration, when the RF antenna 32 is enabled, the RF communication circuit 3 can receive electromagnetic waves of a specific frequency emitted from an external device such as a reader via the RF antenna 32 of the RF communication circuit 3, and can perform non-contact communication between the external device and the RF communication circuit 3 by transmitting and receiving electromagnetic waves.

(i) Circuit Board As the circuit board 23, various insulating boards that are commonly used for printed circuit boards can be used, and both rigid and flexible forms can be used. For example, paper impregnated with phenolic resin or epoxy resin, glass cloth impregnated with epoxy resin, polyimide film, etc. can be mentioned. There is no particular limit to the thickness, but for flexible boards, the thickness can be about 0.01 mm or more and 0.2 mm or less, and for rigid boards, the thickness can be about 0.1 mm or more and 0.4 mm or less.

(ii) RF Chip The RF chip 31 is an IC chip equipped with a CPU or MCU, and the CPU or the like performs various controls, calculations, reading data from memory, writing data to memory, etc. The RF chip 31 can also decode data contained in electromagnetic waves from an external device via the RF antenna 32, and convert data to be transmitted into electromagnetic waves and transmit them to the external device. The RF chip 31 generates the necessary drive power from a current generated by the electromotive force of electromagnetic induction in the RF antenna 32.

The RF chip 31 also includes a RAM as a temporary data storage location, and a ROM as a storage location for the operating system (OS) and fixed application programs. It also includes a non-volatile rewritable memory (NVM) as a storage location for various variable data, variable parameters, and variable application programs. In this embodiment, various controls, calculations, memory access, power generation from electromagnetic waves, data decoding, and conversion of data to electromagnetic waves are all performed by a single IC chip, but it may also be configured such that, for example, some of the power generation, control, calculations, etc. are shared by separate dedicated elements, etc.

(iii) RF Antenna The RF antenna 32 receives electromagnetic waves of a specific frequency emitted from an external device such as a reader, transmits changes in current and voltage caused by the electromotive force of electromagnetic induction generated by an AC magnetic field to the RF chip 31 to which both ends are electrically connected, and converts the changes in current and voltage output from the RF chip 31 into electromagnetic waves of a specific frequency and radiates them so that the external device can receive and decode them.

The RF antenna 32 also has the function of receiving electromagnetic waves from an external device and supplying the current generated by the electromotive force of electromagnetic induction caused by an AC magnetic field to the RF chip 31 as driving power. Various frequency bands of electromagnetic waves can be selected for transmission and reception, such as the LF band using 135 kHz, the HF band using 13.56 MHz, and the UHF band using 920 MHz or 2.45 GHz, but it is necessary to select the antenna shape according to the frequency band being used, for example, a loop antenna for the HF band and a dipole antenna for the UHF band.

In this embodiment, the antenna device 1 is designed to operate at 13.56 MHz, which is in the HF band. When the switch circuit 34 provided in the antenna circuit of the RF communication circuit 3 is set to enable the RF antenna 32, the RF chip 31 and the RF antenna 32 form a closed circuit, and form a resonant circuit with a resonant frequency of 13.56 MHz.

That is, the equivalent circuit of the RF communication circuit 3 formed by the RF chip 31 and the RF antenna ₃₂ is arranged to be a parallel circuit of a coil with an inductance of _L1 and a capacitor with a capacitance of _C1 . In this case, since the resonant frequency f0 when the RF communication circuit 3 is activated is _f0 = 1/( _2π × ( _L1C1 ) ^1/2 ), the parameters of each inductance element and each capacitance element in the RF communication circuit 3 are appropriately determined so that _f0 becomes 13.56, and the inductance and capacitance of the entire circuit obtained by adding these together become _L1 and _C1 .

When the frequency of the electromagnetic waves received by the RF antenna 32 matches the resonant frequency of the RF communication circuit 3, the impedance of the RF communication circuit 3 and the voltage of the electromotive force of electromagnetic induction are at their maximums, maximizing the power generation efficiency and signal reception strength. The peak of this frequency-impedance curve or frequency-voltage curve is prominent at the resonant frequency, and drops sharply if it deviates even slightly from this. Therefore, if the frequency of the electromagnetic waves to be received is higher or lower than the resonant frequency of the RF communication circuit 3 by a certain amount or more, it will be almost impossible to generate power or transmit and receive signals efficiently compared to when receiving power at the resonant frequency, which can have an effect similar to that of essentially disconnecting the antenna circuit of the RF communication circuit 3.

Although it depends on the characteristics of each antenna circuit, when the resonant frequency of an antenna circuit is _f0 , the frequency lower than f0 is _fa , and the frequency higher than _f0 is _fb , the range in which the antenna circuit can resonate is generally considered to be _fa / _f0 is 0.9 or more and _fb / _f0 is 1.1 or less. For electromagnetic waves with _fa or _fb outside this range, the impedance and voltage of the antenna circuit suddenly decrease, and the antenna circuit does not resonate at all or is hardly resonated. In this disclosure, the behavior of the antenna circuit for electromagnetic waves with frequencies outside the specified range is referred to as not resonating.

The resonance of an antenna circuit can also be seen from the induced voltage induced in the antenna circuit at the resonance frequency. In this case, an electromagnetic wave corresponding to the resonance frequency is supplied to the antenna circuit, and the absolute value of the peak value of the induced voltage when the antenna circuit receives or receives the electromagnetic wave is set to _V0 . Here, if the frequency of the electromagnetic wave received or received by the antenna circuit fluctuates, the induced voltage deviates from the peak value and attenuates, and the greater the frequency fluctuation, the greater the degree of attenuation.

If the absolute value of this attenuated induced voltage is _Va , then the range in which the antenna circuit can resonate is considered to be approximately _Va / _V0 equal to or greater than 0.5. For electromagnetic waves outside this range, the antenna circuit does not resonate at all, or is barely resonating at all. In this disclosure, the behavior of the antenna circuit with respect to electromagnetic waves of frequencies outside a specified range in which the attenuation from the peak value of such induced voltage is large is also referred to as not resonating.

The RF antenna 32 can typically be formed by attaching copper foil, aluminum foil, or the like to one side of the circuit board 23 via an adhesive. That is, resist is applied onto the copper foil, and a mask formed to cover areas other than the specified antenna pattern is placed on top of it and exposed to light. After that, the copper foil, or the like in the areas other than the antenna pattern where the resist is not yet hardened, is removed with an etching solution and washed to form the RF antenna 32. This method has the advantage that the thickness of the antenna wire can be made thinner by reducing the thickness of the copper foil, or the like.

The RF antenna 32 may also be formed by a winding method in which a coated conductor wire, the periphery of which is coated with an insulating material, is embedded on one side of the circuit board 23, and instead of the copper wire, a copper alloy wire such as Cu-Ni, Cu-Cr, Cu-Zn, Cu-Sn, or Cu-Be, or various metal wires or metal alloy wires such as iron, stainless steel, or aluminum may be selected. In addition, although the electrical resistance of the antenna circuit will be high, a conductive ink containing metal particles may be printed on one side of the circuit board 23 by silk printing or formed by inkjet printing. These methods are more advantageous in terms of cost and mass production than methods that use etching.

The two ends 32a and 32b of the RF antenna 32, which are the start and end points, are connected to the connection pads 31a and 31b, which are the electrical connection terminals of the RF chip 31. When the RF antenna 32 is formed by the etching method described above, an anisotropic conductive film, i.e., ACF (Anisotropic Conductive Film), is attached to cover the upper surfaces of the ends 32a and 32b of the RF antenna 32, and the RF chip 31, which has conductive protrusions such as gold bumps formed on the connection pads 31a and 31b in advance, is mounted face-down on top of this, and a predetermined heat and pressure is applied for a predetermined time.

In this way, the binder of the thermally melted anisotropic conductive film fills the gap between the RF chip 31 and the RF antenna 32, and the conductive particles of the anisotropic conductive film connect while coming into contact with each other from the end 32a of the RF antenna 32 toward the connection pad 31a of the RF chip 31, thereby providing electrical continuity between the end 32a and the connection pad 31a. The same applies to the end 32b of the RF antenna 32 and the connection pad 31b of the RF chip 31.

In addition to using the anisotropic conductive film described above, the electrical connection between the RF antenna 32 and the RF chip 31 may be made using anisotropic conductive paste (ACP), solder, or a so-called conductive paste in which silver particles are dispersed as a filler in epoxy resin. Also, instead of directly joining the RF chip 31 to the RF antenna 32, the RF chip 31 may be mounted on a substrate equipped with a separate connection terminal, which may then be resin-sealed to form a module, which may then be joined to the RF antenna 32.

In this case, the connection terminals formed on the module can be connected to the ends 32a and 32b of the RF antenna 32 via ACF or the like, or by welding or the like. On the other hand, if the RF antenna 32 is of the wound type, the coating on the two ends 32a and 32b can be removed, and the RF chip 31 modularized as described above can be mounted on top of them, and the connection terminals of the module can be connected to the ends 32a and 32b of the RF antenna 32 by welding or the like.

(iv) Switch Circuit The switch circuit 34 has a switching function for selecting whether to tune the resonant frequency of the above-mentioned RF communication circuit 3 to a predetermined frequency or to shift it therefrom. As shown in Fig. 3, the switch circuit 34 has a configuration in which a switch 35 and an adjustment capacitor 36 are connected in series, and these are also connected in parallel across the wiring toward the end 32a and the wiring toward the end 32b of the RF antenna 32.

In addition to the switch circuit 34, a tuning capacitor 33 is also connected in parallel to the RF communication circuit 3. As described below, the switch 35 can be switched to an open or closed state upon receiving a signal 35s from the control unit 48 of the control chip 41. The switch 35 may be a mechanical contact switch or a non-contact switch that uses a transistor including a field effect transistor.

When the switch 35 is open, the RF communication circuit 3 is in an activated mode in which it resonates with electromagnetic waves of a predetermined frequency. The tuning capacitor 36 is in a floating state within the RF communication circuit 3, and even if a current flows through the RF antenna 32, the tuning capacitor 36 is not charged and has almost no effect on the circuit characteristics of the RF antenna 32. At this time, the capacitance of the entire RF communication circuit 3 mainly depends on the capacitance of the tuning capacitor 33, and the capacitance of the capacitor 33 is selected so that the combined capacitance of this and the capacitance components of the other elements in the circuit is _C1, which is the capacitance of the equivalent circuit described above.

Therefore, at this time, the resonant frequency f ₀ of the RF communication circuit 3 becomes substantially the same as the frequency used for transmitting and receiving with the external device, for example, 13.56 MHz, and good communication is performed between the external device and the antenna device 1. In this case, the RF antenna 32 is enabled, and the non-contact communication function of the RF communication circuit 3 is activated.

On the other hand, when the switch 35 is closed, the RF communication circuit 3 is in a deactivated mode in which it does not resonate with electromagnetic waves of a predetermined frequency. The adjustment capacitor 36 is connected in parallel within the RF communication circuit 3, and when a current flows through the RF antenna 32, electricity is stored in the adjustment capacitor 36 in addition to the capacitor 33. That is, the capacitance component increases in the RF communication circuit 3 as a whole. At this time, the capacitance of the equivalent circuit of the entire circuit of the RF communication circuit 3 shifts to _C11 , which is a capacitance larger than _C1 described above. Therefore, the resonant frequency of the RF communication circuit 3 shifts to _f11 , which is smaller than _f0 described above.

When _f11 falls outside the predetermined range where good communication can be ensured, that is, when the value of _f11 / _f0 is smaller than 0.95, it is difficult to achieve good communication between the external device and the antenna device 1, so the RF antenna 32 is disabled and the non-contact communication function of the RF communication circuit 3 is deactivated. Therefore, when it is desired to disable the RF antenna 32, it is possible to prevent the RF communication circuit 3 from performing communication due to an unintended malfunction, and to prevent noise generation or malfunction in the control circuit 4 due to simultaneous operation of the control circuit 4 and the RF communication circuit 3, interruption of operation due to a lack of power, etc.

In order to further enhance the suppression effect, it is more preferable that the value of _f11 / _f0 is smaller than 0.9. Note that, as will be described in detail later, by adjusting the combined capacitance of the equivalent circuit formed by the tuning capacitor 33 and the adjustment capacitor 36 to _C0 when the switch 35 is closed, the resonant frequency of the RF communication circuit 3 at this time may be configured to be higher than the original resonant frequency.

On the other hand, another case in which the RF antenna 32 is disabled and the non-contact communication function of the RF communication circuit 3 is deactivated is when the induced voltage induced in the RF communication circuit 3 by the received electromagnetic waves drops significantly. When the switch 35 of the RF communication circuit 3 is open, the absolute value of the peak value of the induced voltage in the RF communication circuit 3 when it resonates with electromagnetic waves of a predetermined frequency is set to _V01 , and when the switch 35 is closed, the absolute value of the induced voltage in the RF communication circuit 3 when it receives electromagnetic waves of the predetermined frequency is set to _V1 . At this time, if the value of _V1 / _V01 is smaller than 0.5, it is difficult to communicate well between the external device and the antenna device 1, so the RF antenna 32 is disabled and the non-contact communication function of the RF communication circuit 3 is deactivated.

The reason why the induced voltage of the RF communication circuit 3 is thus greatly attenuated relative to the peak value is that, as described above, by closing the switch 35 of the RF communication circuit 3, the resonant frequency of the RF communication circuit 3 shifts to _f11, which is smaller than _f0 , and therefore the RF communication circuit 3 does not resonate even when it receives an electromagnetic wave with a frequency of _f0 .

(v) Other Circuits Although details will be described later, the RF communication circuit 3 includes, in addition to the above, a rectifier circuit 37 that converts the current generated by the electromotive force of electromagnetic induction due to the electromagnetic wave received by the RF antenna 32 into a direct current, and a field effect transistor 38 that applies load modulation to the electromagnetic wave received by the RF antenna 32 and generates an electromagnetic wave waveform corresponding to the transmission data by turning on and off in response to a signal 38s from the connection pad 31f of the RF chip 31. In this embodiment, in order to supply the direct current generated by the rectifier circuit 37 to the RF chip 31, the tips of two wirings branching from the rectifier circuit 37 are electrically connected to the connection pads 31c and 31d of the RF chip 31, respectively. However, the function of the rectifier circuit 37 may be provided inside the RF chip 31.

(b) Control Circuit As shown in Fig. 1, the control circuit 4 includes a control chip 41 and a control antenna 42, both ends of which are electrically connected in parallel to the control chip 41 and the power supply unit 6. As shown in Fig. 2, the control circuit 4 includes a circuit board 23 that supports the control chip 41, the control antenna 42, the power supply unit 6, and the bioinformation sensor 5. On the other hand, as shown in Fig. 3, the control circuit 4 includes a tuning capacitor 43 for matching the resonant frequency in the same manner as the RF communication circuit 3, a switch circuit 44 for switching a part of the circuit, and a rectifier circuit 47 that receives power at the control antenna 42 and rectifies the current generated by the electromotive force of electromagnetic induction.

The switch circuit 44 can also enable or disable the control antenna 42 depending on the on/off state of the internal switch 45. With this configuration, the control circuit 4 can receive electromagnetic waves of a specific frequency emitted from an external device such as a reader at the control antenna 42 of the control circuit 4 only when the control antenna 42 is enabled, and can supply power to charge the power supply unit 6 and to obtain drive power for the control chip 41 and the biometric sensor 5.

The essential components of the control circuit 4 are the control antenna 42, the switch circuit 44, and either the control chip 41 or the power supply unit 6. In this embodiment, both ends of the control antenna 42 are connected in parallel to the control chip 41 and the power supply unit 6, but both ends of the control antenna 42 may be connected only to the control chip 41 or only to the power supply unit 6.

(i) Circuit Board The circuit board 23 is shared with the circuit board 23 supporting the RF chip 31 and the RF antenna 32 described above, but some of the boards may be separated depending on the arrangement and size of the devices mounted thereon. For example, as shown in Fig. 2, in this embodiment, in order to align the surface 5a of the biometric sensor 5 to be substantially flush with the surface 21a of the core layer 21, the circuit board 23a mounting the control chip 41 and the power supply unit 6 and the circuit board 23b mounting the biometric sensor 5 are disposed separately from each other.

This is because the circuit boards 23a and 23b are arranged at different positions in the thickness direction of the antenna device 1. In this case, it is preferable to connect the circuit boards 23a and 23b with the connecting wiring portion 23c, which is a conductive member, in order to electrically connect, for example, the power supply unit 6 and the biometric information sensor 5.

(ii) Control Chip The control chip 41 is an IC chip equipped with a CPU or MCU, similar to the RF chip 31. As shown in the block diagram of Fig. 4, the control chip 41 further includes a control unit 48 and a memory 49. The control chip 41 has a function of instructing and driving the biometric information sensor 5 to acquire biometric information using an input signal from the power switch 8 as a trigger, and a function of determining whether or not a predetermined biometric authentication condition is met, i.e., whether or not the biometric information is used by a legitimate user, by collating the biometric information acquired by the biometric information sensor 5 with pre-registered information stored in the memory 49.

Furthermore, based on the result of this determination, the control chip 41 can instruct the RF antenna 32 of the RF communication circuit 3 to be enabled or disabled, and the control antenna 42 of the control circuit 4 to be enabled or disabled. Specifically, the control chip 41 can output, via the control unit 48, a signal 35s that opens or closes the switch 35 of the switch circuit 34, and a signal 45s that opens or closes the switch 45 of the switch circuit 44.

The control chip 41 may also include, for example, an image processing circuit that extracts feature points from biometric information such as the user's fingerprint information acquired by the biometric sensor 5, and a control circuit that estimates the amount of stored power in the power supply unit 6 by monitoring the amount of current and voltage from the power supply unit 6 and performs control according to the results. Control according to the amount of stored power in the power supply unit 6 may, for example, stop the operation of the biometric sensor 5 that requires power or slow down the processing speed to reduce power consumption when the amount of stored power in the power supply unit 6 falls below a certain level.

The control unit 48 and image processing circuit described above may be provided as a separate dedicated chip or dedicated element connected to the control chip 41 by wiring, rather than as part of the control chip 41. Also, the two ends 42a and 42b, which are the start and end points of the control antenna 42, are connected to connection pads 41a and 41b, which are electrical connection terminals of the control chip 41, respectively, and the same method of connection as the method of connecting the connection pads 31a and 31b of the RF chip 31 to the ends 32a and 32b of the RF antenna 32 can be applied.

(iii) Control Antenna The control antenna 42 is an antenna separate from the RF antenna 32, and has a function of receiving electromagnetic waves of a predetermined frequency emitted from an external device such as a reader, and supplying a current generated by the electromotive force of electromagnetic induction caused by an AC magnetic field to the control chip 41 and the power supply unit 6 as driving power. In addition, the control antenna 42 may have a function of directly supplying the current generated by the electromotive force of electromagnetic induction to the bioinformation sensor 5 as driving power for the bioinformation sensor 5. The frequency of the electromagnetic waves used for receiving power by the control antenna 42 can be selected from the LF band, HF band, UHF band, etc., as with the RF antenna 32, but from the viewpoint of simplifying the configuration of an external device such as a reader, it is preferable to make it the same as the frequency of the RF antenna 32. In this embodiment, the frequency target value of the control antenna 42 is 13.56 MHz, as with the RF antenna 32.

When the switch circuit 44 is set to activate the control antenna 42, the control chip 41 or the power supply unit 6 and the control antenna 42 form a closed circuit, and form a resonant circuit with a resonant frequency of 13.56 MHz. That is, the equivalent circuit of the control circuit 4 is arranged to be a parallel circuit of a coil with an inductance of _L2 and a capacitor with a capacitance of _C2 .

In this case, since the resonant frequency _f0 when the control circuit 4 is activated is _f0 = ₁ /(2π × ( _L2C2 ) ^1/2 ), the parameters of each inductance element and each capacitance element in the control circuit 4 are appropriately determined so that _f0 becomes 13.56, and the combined inductance and capacitance of the entire circuit become _L2 and _C2 , similarly to the RF antenna 32. Note that, as in this embodiment, it is preferable that the original resonant frequencies _f0 of the RF communication circuit 3 and the control circuit 4 are the same, but a slight deviation is acceptable as long as it does not cause practical problems.

When the frequency of the electromagnetic waves received by the control antenna 42 matches the resonant frequency of the control circuit 4, the impedance of the control circuit 4 and the voltage of the electromotive force of electromagnetic induction are at their maximums, maximizing the power generation efficiency. On the other hand, if the frequency of the electromagnetic waves to be received is higher or lower than the resonant frequency of the control circuit 4 by a certain amount, power generation becomes almost impossible as efficiently as when power is received at the resonant frequency, which can have an effect similar to that of essentially disconnecting the antenna circuit of the control circuit 4.

The method for forming the control antenna 42 can be the same as that for the RF antenna 32, and forming it in the same method as the RF antenna 32 is preferable from the standpoint of material costs and process simplification. In this embodiment, the control antenna 42 is formed by an etching method, like the RF antenna 32. Also, the loop coil of the control antenna 42 is formed inside the opening of the loop coil of the RF antenna 32, as shown in FIG. 1.

Generally, the magnetic field strength of electromagnetic induction caused by electromagnetic waves received by a loop antenna is proportional to the number of turns of the loop antenna and the area of the opening. Therefore, whether the control antenna 42 or the RF antenna 32 should be placed on the inside can be appropriately designed by taking into consideration the priority of the communication sensitivity and strength of the RF communication circuit 3 and the power generation efficiency of the control circuit 4.

Two ends 42a and 42b, which are the start and end points of the control antenna 42, are connected to connection pads 41a and 41b, which are electrical connection terminals of the control chip 41, respectively. In addition, the two ends of the control antenna 42 each branch off and are connected to the power supply unit 6 in addition to the control chip 41. The electrical connection between the control antenna 42 and the control chip 41 or the power supply unit 6 can be made in the same manner as the connection between the RF antenna 32 and the RF chip 31 described above.

(iv) Switch Circuit The switch circuit 44 has a switch function for selecting whether to tune the resonant frequency of the control circuit 4 to a predetermined frequency or to shift it therefrom, similar to the switch circuit 34 of the above-described RF communication circuit 3. The switch circuit 44 has a configuration in which a switch 45 and an adjustment capacitor 46 are connected in series, and these are also connected in parallel across the wiring toward the end 42a of the control antenna 42 and the wiring toward the end 42b.

In addition to the switch circuit 44, a tuning capacitor 43 is also connected in parallel to the control circuit 4. As described above, the switch 45 can be switched to an open or closed state upon receiving a signal 45s from the control unit 48 of the control chip 41. The switch 45 can be of the same type as the switch 35, and one of the two switches may be of a contact type and the other of a non-contact type.

When the switch 45 is open, the control circuit 4 is in an activation mode in which it resonates with electromagnetic waves of a predetermined frequency. The adjustment capacitor 46 is in a floating state within the control circuit 4, and the capacitance of the entire control circuit 4 depends mainly on the capacitance of the tuning capacitor 33, regardless of the capacitor 46, and the capacitance of the capacitor 33 is selected so that the total capacitance of this and the capacitance components of the other elements in the circuit is _C2, which is the capacitance of the above-mentioned equivalent circuit. Therefore, at this time, the resonant frequency _f2 of the control circuit 4 is approximately the same as the frequency used for transmitting and receiving with an external device, for example, 13.56 MHz, and communication between the external device and the antenna device 1 is performed well. In this case, the control antenna 42 is enabled, and the power acquisition function of the control circuit 4 is activated.

On the other hand, when the switch 45 is closed, the control circuit 4 is in a deactivated mode in which it does not resonate with electromagnetic waves of a predetermined frequency. The adjustment capacitor 46 is connected in parallel within the control circuit 4, and when a current flows through the control antenna 42, electricity is stored in the adjustment capacitor 46 in addition to the capacitor 43. That is, the capacitance component of the control circuit 4 as a whole increases. At this time, the capacitance of the equivalent circuit of the control circuit 4 shifts to _C21, which is a capacitance larger than the above _C2 . Therefore, the resonant frequency of the control circuit 4 shifts to _f21 , which is smaller than the above _f0 .

When _f21 falls outside the predetermined range where good communication can be ensured, that is, when the value of _f21 / _f0 is smaller than 0.95, it is difficult to achieve good communication between the external device and the antenna device 1, so the control antenna 42 is disabled and the power acquisition function of the control circuit 4 is deactivated. Therefore, when it is desired to disable the control antenna 42, communication due to an unintended malfunction of the control circuit 4 is suppressed, and noise generation or malfunction in the control circuit 4 due to simultaneous operation of the RF communication circuit 3 and the control circuit 4, interruption of operation due to a lack of power, etc. are suppressed.

In order to further enhance the suppression effect, it is more preferable that the value of _f21 / _f0 is smaller than 0.9. By adjusting the combined capacitance of the equivalent circuit formed by tuning capacitor 43 and adjustment capacitor 46 to _C0 when switch 45 is closed, the resonant frequency of control circuit 4 at this time may be configured to be higher than the original resonant frequency, as in the case of RF communication circuit 3 described above.

Another case in which the control antenna 42 is disabled and the power acquisition function of the control circuit 4 is inactivated is when the induced voltage induced in the control circuit 4 by the received electromagnetic waves drops significantly. When the switch 45 of the control circuit 4 is open, the absolute value of the peak value of the induced voltage in the control circuit 4 when it resonates with electromagnetic waves of a predetermined frequency is set to _V02 , and when the switch 45 is closed, the absolute value of the induced voltage in the control circuit 4 when it receives electromagnetic waves of the predetermined frequency is set to _V2 . In this case, if the value of _V2 / _V02 is smaller than 0.5, it is difficult to communicate well between the external device and the antenna device 1, so the control antenna 42 is disabled and the power acquisition function of the control circuit 4 is inactivated.

The reason why the induced voltage of the control circuit 4 is thus greatly attenuated relative to the peak value is that, as described above, by closing switch 45 of the control circuit 4, the resonant frequency of the control circuit 4 shifts to _f21, which is smaller than _f0 , and therefore the control circuit 4 does not resonate even when it receives an electromagnetic wave with a frequency of _f0 .

Here, from the viewpoint of simplifying the device configuration of an external device such as a reader, it is preferable that the transmission of electromagnetic waves of the same frequency can activate the non-contact communication function of the RF communication circuit 3 of the antenna device 1 and the power acquisition function of the control circuit 4. For this reason, in this embodiment, the resonant frequency f ₀ when the RF communication circuit 3 is enabled and the resonant frequency f ₀ when the control circuit 4 is enabled are set to the same frequency, but this is not limited to this.

For example, if the frequency range of electromagnetic waves in which the RF communication circuit 3 can be enabled is a first range and the frequency range in which it can be disabled is a second range, the frequency range of electromagnetic waves in which the control circuit 4 can be enabled is a third range and the frequency range in which it can be disabled is a fourth range, it is preferable that the first range and the second range at least partially overlap, and that the first range and the fourth range, and the third range and the second range do not overlap. This is because, under these conditions, an external device can activate the non-contact communication function of the RF communication circuit 3 of the antenna device 1 and the power acquisition function of the control circuit 4 by transmitting electromagnetic waves of the same frequency, and can reliably activate or deactivate either one of the functions.

Furthermore, in determining the above-mentioned optimal _f0 , _f11 , and _f2 , the RF communication circuit 3 and the control circuit 4 need to appropriately determine the capacitances of the tuning capacitors 33, 43 and the adjustment capacitors 36, 46. Therefore, in general, the capacitances of the adjustment capacitor 36 of the switch circuit 34 and the adjustment capacitor 46 of the switch circuit 44 may be determined to be different from each other.

In this embodiment, the switch circuit 34 of the RF communication circuit 3 and the switch circuit 44 of the control circuit 4 are provided as separate configurations, but the switch circuit 34 and the switch circuit 44 may be configured as a single, common circuit configuration that is shared by the RF communication circuit 3 and the control circuit 4. In this case, the switch of the shared switch circuit has a structure known as a double-throw switch or C contact, and is capable of switching between one state and another state.

In one state, the switch of the switch circuit is closed when viewed from the RF communication circuit 3, and the switch of the switch circuit is open when viewed from the control circuit 4. On the other hand, in the other state, the switch of the switch circuit is open when viewed from the RF communication circuit 3, and the switch of the switch circuit is closed when viewed from the control circuit 4. This configuration has the advantage of simplifying the circuit configuration and control, since there is no need to have multiple switch circuits and there is no need for the control unit to instruct both the switch of the RF communication circuit 3 and the switch of the control circuit 4.

(v) Biometric Information Sensor The biometric information sensor 5 is a sensor for acquiring biometric information specific to a user for specific user authentication etc., and various target information can be selected, such as fingerprint information acquired from the user's finger, vein information acquired from the finger or palm, iris information acquired from the eye, voiceprint information acquired from the voice, or information such as the user's blood pressure or pulse rate. In this embodiment, a fingerprint sensor that acquires fingerprint information is used as the biometric information sensor 5.

The fingerprint sensor, which is the biometric information sensor 5, can read the necessary fingerprint information when the user places his/her finger on the surface 5a of the housing of the biometric information sensor 5, which is exposed on approximately the same surface as the surface 21a of the card, which is the antenna device 1. Any reading method can be used, but one possible method is to provide lighting and a CCD camera on the surface 5a, shine illumination light on the finger placed on the biometric information sensor 5, and capture the intensity of the reflected light as data for each pixel of the CCD camera.

(vi) Power supply unit The power supply unit 6 is a secondary battery that stores a current generated by the electromotive force of electromagnetic induction of the electromagnetic waves received by the control antenna 42, but may be a primary battery or a simple capacitive element for temporarily storing electricity. The power supply unit 6 may be a normal lithium ion secondary battery, or may be an all-solid-state battery having an electrolyte layer that uses an oxide as a solid electrolyte material.

The power supply unit 6 may also be configured to store current generated by the electromotive force of electromagnetic induction of the electromagnetic waves received by the RF antenna 32, in addition to the current from the control antenna 42. In this embodiment, the ends 42a and 42b of the control antenna 42 are each branched and connected to the control chip 41 and the power supply unit 6. However, the ends 42a and 42b of the control antenna 42 may be connected to only one of the control chip 41 or the power supply unit 6.

(vii) Other Circuits Although details will be described later, in addition to the components described above, the control circuit 4 is also equipped with a rectifier circuit 47 that converts the current generated by the induced electromotive force due to electromagnetic induction caused by the electromagnetic waves received by the control antenna 42 into a direct current.

(c) Substrate and Others Because the antenna device 1 of this embodiment is in the form of a card, it has the additional components described below, but these are not essential components of the antenna device 1. As described above, it is sufficient for the antenna device 1 to have the RF communication circuit 3 and the control circuit 4. Below, the additional configurations that are provided in the antenna device 1, which is a card of this embodiment, will be described.

2, the antenna device 1 has core layers 21 and 22, which are substrates 2, on the front and back sides, respectively, and has a configuration in which the above-mentioned RF communication circuit 3 and control circuit 4 are sandwiched between the core layers 21, 22. A wide variety of white or colored plastic sheets can be used as the core layers 21 and 22, and the following single films or composite films thereof can be used.

For example, polyethylene terephthalate (PET), PET-G (terephthalic acid-cyclohexanedimethanol-ethylene glycol copolymer), polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polycarbonate, polyamide, polyimide, cellulose diacetate, cellulose triacetate, polystyrene, ABS, polyacrylic ester, polypropylene, polyethylene, polyurethane, etc. The thickness of the core sheet can be appropriately selected taking into account the overall thickness of the card, but can be, for example, about 0.1 mm or more and 0.5 mm or less.

Instead of the core layer 21, a laminate of an opaque core layer and a transparent oversheet layer may be used. In this way, like a normal credit card, the surface of the core layer is printed and its upper surface is covered with a transparent oversheet as a protective layer, making the printing on the surface of the core layer less likely to peel off and giving it a glossy appearance. Alternatively, an oversheet layer to which a magnetic stripe has been thermally transferred may be laminated onto the core layer, and the upper surface of the oversheet layer may be printed to conceal the magnetic stripe, resulting in a highly designed card with an invisible magnetic stripe. The same applies to the core layer 22.

(ii) Spacer As described above, the antenna device 1 has core layers 21 and 22 on the front and back surfaces, respectively, and has a structure in which the RF communication circuit 3 and the control circuit 4 are sandwiched inside. Here, as shown in Fig. 2, in the cross section of the RF communication circuit 3 and the control circuit 4, a thin region where only the circuit board 23 exists coexists with a thick region where various devices such as the RF chip 31, the control chip 41, the bioinformation sensor 5, and the power supply unit 6 are mounted on the circuit board 23, and due to the influence of this, it is relatively difficult to maintain the surface smoothness of the core layers 21 and 22.

To suppress undulations in the core layers 21 and 22 caused by uneven thicknesses of the RF communication circuit 3 and the control circuit 4, the antenna device 1 is provided with a spacer 24 that is partially placed on the circuit board 23. To avoid interference with various devices, the spacer 24 has through holes and notches in areas corresponding to the devices. The material and thickness of the spacer 24 can be the same as those of the core layer.

(iii) Adhesive In addition to the spacers described above, in the antenna device 1, gaps other than the spacers 24 formed between the core layers 21 and 22 on the front and back sides and the internal RF communication circuit 3 and control circuit 4 are filled with a liquid adhesive 40 in the portions corresponding to the gaps in order to achieve close contact and sealing between the core layers 21 and 22 and the RF communication circuit 3 and control circuit 4, and to further suppress waviness of the core layers 21 and 22 on the front and back sides. The adhesive 40 can be made of various materials such as room temperature curing type and heat curing type, but it is preferable to select a material that provides a certain degree of flexibility as a card even after curing, such as a natural rubber or synthetic rubber adhesive, or a urethane adhesive using a urethane reaction of polyisocyanate and polyol.

The antenna device 1 may be formed without using the liquid adhesive as described above, as in the case of ordinary magnetic cards or IC cards. In this case, a heat-sealable adhesive sheet is sandwiched between the non-self-adhesive circuit board 23 and the spacer 24, and between the circuit board 23 and the core layer 22, and a stainless steel plate is placed on the outer surfaces of each of the core layers 21 and 22, and a predetermined heat pressure is applied from both sides. This makes it possible to obtain an antenna device 1 in which the internal layers of the core layer 22, adhesive sheet, circuit board 23, adhesive sheet, spacer 24, and core layer 21 are integrated by heat fusion.

(iv) Display unit, power switch, etc. In addition to the above, the antenna device 1 of this embodiment has additional functions that are not essential components. As shown in FIG. 1, the antenna device 1 includes a display unit 7 and a power switch 8 that are exposed on the surface 21a of the card that is the antenna device 1, and are adjacent to each other. The display unit 7 can display the operating state of the antenna device 1 and the functions that can be operated at that time. The display unit 7 of this embodiment is two LED lamps, one of which emits green light indicating normal operation and the other emits red light indicating abnormal operation or warning, but is not limited to this, and the display unit 7 may be one that emits multiple colors.

Alternatively, the display unit 7 may be a liquid crystal display, electronic paper, or the like, capable of displaying characters, etc. The power switch 8 is used as a device that outputs a trigger signal that starts the antenna device 1 so as to activate the biometric authentication function and the non-contact communication function when pressed by a user when using the antenna device 1. For example, when a user presses the power switch 8, power supply from the power supply unit 6 or the control circuit 4 to the biometric information sensor 5 is started, and fingerprint matching can be performed by the biometric information sensor 5.

However, such a display unit 7 and power switch 8 can be substituted with other configurations. For example, the display unit 7 can be omitted and the state of the antenna device 1 can be notified by voice or the like. Also, instead of providing a power switch 8, this function can be substituted with another sensor or the like as described below. A configuration in which the power switch 8 is simply not present can also be used, in which case the description of this embodiment can be replaced with an assumption that the power switch 8 is always pressed.

(d) Operation of the Antenna Device Next, the operation, function and function of the antenna device 1 according to the first embodiment will be described mainly with reference to Figures 4 to 6. Figures 5 and 6 are flow charts for explaining the operation of the antenna device 1.

(i) Activation of Antenna Device and Biometric Authentication As shown in Fig. 5, first, the user presses the power switch 8 of the antenna device 1 to activate the antenna device 1 (step S201). If the power switch 8 is not provided, the antenna device 1 may behave in the same manner as when the power switch 8 is pressed when the control antenna 42 detects that the antenna device 1 is held over an external device. In this case, steps S201 to S203 in Fig. 5 are not performed, the switch 35 of the switch circuit 34 is normally closed, and the switch 45 of the switch circuit 44 is normally open. Then, the process starts from step S204, triggered by the detection of power reception by the control antenna 42.

Before the power switch 8 is pressed, the non-contact communication function of the RF communication circuit 3 is inactivated, i.e., the switch 35 of the switch circuit 34 is closed. Meanwhile, the power acquisition function of the control circuit 4 is also inactivated, i.e., the switch 45 of the switch circuit 44 is closed. However, before the power switch 8 is pressed, the switch 45 of the switch circuit 44 may be open, and the power acquisition function of the control circuit 4 may be activated. Also, before the power switch 8 is pressed, the power supply wiring connecting the power supply unit 6 to the control chip 41 and the biometric sensor 5 is open, and no power is supplied from the power supply unit 6 to the control chip 41 or the biometric sensor 5.

When the power switch 8 is pressed, the power supply unit 6 starts supplying power to the control chip 41 (step S202). When the control chip 41 is started, the control chip 41 instructs the switches 35 and 45 via the control unit 48, which functions as a function of a CPU, etc., to keep the switch 35 of the switch circuit 34 of the RF communication circuit 3 closed and to switch the switch 45 of the switch circuit 44 of the control circuit 4 to open (step S203). As a result, the non-contact communication function of the antenna device 1 remains inactive and the power acquisition function of the control circuit 4 is activated.

In this state, when the control circuit 4 receives electromagnetic waves of a specific frequency, it resonates, and the current generated by the electromotive force of electromagnetic induction can be used to power the control chip 41 or to store electricity in the power supply unit 6 (step S204). In addition, power can be supplied to the biometric sensor 5 by receiving power from the control antenna 42 either directly or via the power supply unit 6. Therefore, as long as the control circuit 4 continues to receive electromagnetic waves of a specific frequency, the control chip 41 and the biometric sensor 5 can be continuously driven.

In this state, the user can place his/her finger on the surface 5a of the biometric sensor 5, which allows the biometric sensor 5 to acquire the necessary biometric information from the user's finger (step S205). Here, the biometric sensor 5 may start acquiring biometric information by detecting a change in sensitivity of the CCD sensor when the finger is placed on the surface 5a, or by detecting a capacitance sensor, temperature sensor, or load sensor provided near the biometric sensor 5. Alternatively, the biometric sensor 5 may be configured to continuously repeat the operation of acquiring biometric information for a certain period of time after the power switch 8 is pressed.

The acquisition of biometric information by the biometric information sensor 5 can be restricted by certain conditions, such as a time limit or a limit on the number of times. In this embodiment, for example, restrictions are imposed such as within one minute after the power switch 8 is pressed, and no more than two failures in biometric authentication. This makes it possible to prevent problems such as the user's own biometric information being acquired at a time unintended by the user, or repeated biometric authentication processing by someone else impersonating the user, etc.

Here, if the biometric information sensor 5 has not yet acquired biometric information, the control chip 41 determines whether or not a predetermined condition is met (step S221). If this condition is met, the above steps S204 and S205 are repeated. On the other hand, if the predetermined condition is not met (if the time exceeds one minute or if biometric authentication fails three times, etc.), the process continues to flow C (see FIG. 6). Note that the determination of whether or not the predetermined condition is met and the subsequent processes may be performed by the biometric information sensor 5 itself, without going through the control chip 41.

Furthermore, when biometric information is acquired by the biometric information sensor 5 within a predetermined condition, the control chip 41 reads out the biometric information registered as that of the legitimate user stored in its own memory 49, and compares and collates it with the acquired biometric information (step S206). There are various methods for comparing and collating the acquired biometric information with the biometric information of the legitimate user registered in advance. It is also possible to convert image information such as the fingerprint of the legitimate user acquired as density information for each pixel by a CCD camera or the like into grayscale or binarization and store it as is in the memory 49 of the control chip 41, but this would result in a huge amount of data.

For this reason, it is convenient to extract certain features from this imaging information and store them in memory 49 as template information with a small amount of data while retaining the features of the original imaging information, and when acquiring biometric information using the biometric information sensor 5 for authentication, extract certain features using the same algorithm as used at the time of registration and compare and match this with the registered template information. This reduces the memory occupation amount of the control chip 41 and shortens the time required for biometric authentication.

When the control chip 41 determines that the biometric information acquired by the biometric sensor 5 is from the same range as the biometric information of the legitimate user stored in the memory 49 of the control chip 41, the biometric authentication is successful (step S207). At this time, a display indicating the success of the biometric authentication can be displayed, for example, by turning on the LED lamp of the display unit 7 in green (step S208). This allows the antenna device 1 to clearly inform the user that the user's biometric authentication has been successful. On the other hand, when it is determined that the two are not from the same range, the biometric authentication is unsuccessful (step S207). In this case, this can be displayed, for example, by turning on the display unit 7 in red (step S231).

If the biometric authentication is successful, the control chip 41 instructs the switches 35 and 45 via the control unit 48 to switch the switch 45 of the switch circuit 44 of the control circuit 4 from open to closed, and at the same time, or after a certain time has elapsed after the switch 45 is switched, to switch the switch 35 of the switch circuit 34 of the RF communication circuit 3 from closed to open (step S209).

As a result, the power acquisition function of the control circuit 4 of the antenna device 1 transitions from an activated state to a deactivated state. At the same time, or after a certain period of time has elapsed, the non-contact communication function of the RF communication circuit 3 transitions from a deactivated state to an activated state. By shifting the switching timing of the switches 45 and 35 by a certain period of time, it is possible to reduce the possibility that current will flow into both the control circuit 4 and the RF communication circuit 3, causing the RF communication circuit 3 to malfunction due to momentary current and voltage fluctuations. The period of time can be, for example, 1 μsec or more and 10 sec or less.

Depending on how the circuit is configured, after the instruction to switches 35 and 45 (step S209), the non-contact communication function of the RF communication circuit 3 transitions from a deactivated state to an activated state slightly earlier than the transition of the power acquisition function of the control circuit 4 of the antenna device 1 from an activated state to a deactivated state. After that, after a certain period of time has elapsed, the power acquisition function of the control circuit 4 of the antenna device 1 transitions from an activated state to a deactivated state. This period of time can be, for example, 1 sec or less. Within this range, the time during which the RF communication circuit 3 and the control circuit 4 are simultaneously activated is short, so that the effect on each circuit can be limited. After that, the processing of the antenna device 1 continues to flow B (see FIG. 6).

On the other hand, if the biometric authentication fails, the control chip 41 determines whether the above-mentioned predetermined conditions (e.g., within one minute and biometric authentication failures not exceeding two times) are met (step S232), and if so, repeats the above-mentioned steps S204 and onward. If the predetermined conditions are not met, the process continues to flow D (see FIG. 6). Note that the predetermined conditions listed in step S221 and the predetermined conditions listed in step S232 may be the same or different.

(ii) Non-contact communication Next, the process of the antenna device 1 according to flow B shown in FIG. 6 will be described. As described above, flow B is a flow after the user has succeeded in biometric authentication, the power acquisition function of the control circuit 4 of the antenna device 1 is deactivated, and the non-contact communication function of the RF communication circuit 3 is activated. In this state, the RF communication circuit 3 resonates when it receives electromagnetic waves of a predetermined frequency, transmits changes in current and voltage caused by the electromotive force of electromagnetic induction to the RF chip 31 to which both ends are electrically connected, and converts the changes in current and voltage output from the RF chip 31 into electromagnetic waves of a predetermined frequency and radiates them so that an external device can receive and decode them (step S211). In addition, the RF antenna 32 can also receive electromagnetic waves of a predetermined frequency from an external device and supply the current caused by the electromotive force of electromagnetic induction to the RF chip 31 as driving power.

Here, a restriction based on a predetermined condition, such as a time restriction, can be set for maintaining the activated state of the RF communication circuit 3. In this embodiment, for example, a restriction of 10 seconds or less is set from the point when the power acquisition function of the control circuit 4 of the antenna device 1 is deactivated and the non-contact communication function of the RF communication circuit 3 transitions to an activated state. This makes it possible to prevent the non-contact communication function of the antenna device 1 from being used by another person to impersonate the user at a time unintended by the user, without going through biometric authentication by the user. These restrictions can be set and adjusted as desired, taking into account the circuit characteristics, etc.

The control chip 41 determines whether or not the predetermined condition is met (step S212), and if it is met, the contactless communication function of the antenna device 1 can be used continuously (step S211), and if the predetermined condition is not met (e.g., if the time exceeds 10 minutes), the control chip 41 switches the switch 35 of the switch circuit 34 of the RF communication circuit 3 from open to closed via the control unit 48, and keeps the switch 45 of the switch circuit 44 of the control circuit 4 closed (step S213). However, the switch 45 of the switch circuit 44 may be switched to open, and the power acquisition function of the control circuit 4 may be activated.

The predetermined condition for maintaining the RF communication circuit 3 in an activated state is not limited to the above, and may be, for example, that the control chip 41 uses a dedicated sensor or the like to monitor the operating state of the RF communication circuit 3, such as the magnetic field strength and current generated by the RF antenna 32, and that a magnetic field strength equal to or greater than a certain level is obtained, or that the time during which the magnetic field strength falls below this level is within a predetermined time, etc. As another method, the RF chip 31 and the control chip 41 may be connected by wiring, and the RF chip 31 may output a signal indicating that it is operating to the control chip 41, and the predetermined condition may be that the signal can be received, or that the time during which the signal cannot be received is within a predetermined time, etc.

After that, just like the state before the power switch 8 was pressed, the power supply wiring connecting the power supply unit 6 to the control chip 41 and the biometric sensor 5 is opened, and power supply from the power supply unit 6 to the control chip 41 and the biometric sensor 5 is stopped (step S214). As a result, the antenna device 1 returns to a state in which both the non-contact communication function of the RF communication circuit 3 and the power acquisition function of the control circuit 4 are inactivated.

Furthermore, the processing of the antenna device 1 relating to flows C and D shown in FIG. 5 will be described. As described above, flow C is the flow after the biometric information sensor 5 does not acquire biometric information and does not satisfy the predetermined condition, and flow D is the flow after the biometric authentication fails and does not satisfy the predetermined condition. In this case, as shown in FIG. 6, both follow the flow from step S213 described above. That is, in order to deactivate the RF communication circuit 3 and the control circuit 4, both switch 35 of switch circuit 34 and switch 45 of switch circuit 44 are closed. Then, the power supply wiring connecting the power supply unit 6 to the control chip 41 and the biometric sensor 5 is opened.

(e) Manufacturing Method of the Antenna Device Next, an example of a manufacturing method of the card-shaped antenna device 1 of this embodiment will be described. Figures 7 and 8 are diagrams illustrating the manufacturing process of the antenna device of the first embodiment.

(i) Attachment of adhesive to substrate First, as shown in Fig. 7(a), an adhesive 50 such as a double-sided adhesive tape having a predetermined thickness and area is attached to a predetermined position on one side of the core layer 22, which is one of the substrates 2 that form the front and back surfaces of the antenna device 1. The outer shape of the substrate 2 when viewed in a plan view is approximately rectangular, similar to the outer shape of the antenna device 1, but in terms of mass production, it is preferable to manufacture the antenna devices 1 as a multi-sided laminate arranged vertically and horizontally in a matrix shape, and finally punch out each antenna device 1 into a card shape. In Figs. 7 and 8, for the sake of simplicity of explanation, the diagram shows one antenna device 1 per sheet, but as described above, the manufacturing method of a multi-sided laminate is also included.

The adhesive 50 is provided to position and temporarily fix the circuit board 23 at a predetermined position relative to the core layer 22 when the circuit board 23 with various devices mounted on the surface opposite the core layer 22 is placed. The thickness of the adhesive 50 can be changed appropriately according to the thickness of the device and circuit board 23 to be fixed thereon and the planned position in the thickness direction, as described below. Various known materials can be used for the adhesive 50, such as natural rubber, synthetic rubber, silicone resin, urethane resin, and acrylic resin adhesives. If necessary, a rosin or phenol resin tackifier, a softener such as a plasticizer, etc. can be added to the adhesive.

(ii) Formation of antennas and attachment of devices to circuit board On the other hand, the RF antenna 32 and the control antenna 42 are formed on one side or both sides as necessary of the circuit board 23, and various devices are attached thereto. The method of forming the RF antenna 32 and the control antenna 42, and the method of connecting the RF chip 31 and the control chip 41 to the RF antenna 32 and the control antenna 42 are as described above. In addition, a wiring pattern for achieving electrical connection between various devices is formed on one side or both sides as necessary of the circuit board 23 in accordance with the antenna formation method.

Then, the power supply unit 6, the bioinformation sensor 5, the switch circuits 34 and 44, various resistive elements, capacitive elements, rectifying elements, switches, etc. are mounted and fixed on the circuit board 23. In addition, to reinforce and prevent corrosion of the electrical contact parts between the circuit board 23 and the various devices, the contact parts may be covered and protected by filling them with a sealant such as epoxy resin, if necessary.

(iii) Attachment of the circuit board with devices to the substrate Next, as shown in Fig. 7(b), the circuit board 23 with various devices attached is placed on the surface of the adhesive material 50 of the core layer 22, one surface of which is attached with the adhesive material 50, and is adhered and fixed. The arrangement of these devices and the circuit board 23 in the antenna device 1 is finally fixed by an adhesive filling process described later, but in order to prevent the arrangement of the devices and the circuit board 23 from being displaced due to the influence of the flow of the adhesive, it is intended to temporarily fix them to the core layer 22 in advance.

Here, for example, the circuit board 23b on which the biometric sensor 5 is mounted is separate from the circuit board 23a on which other devices are mounted. Also, the thickness of the adhesive material 50 corresponding to the circuit board 23b is thicker than the thickness of the adhesive material 50 corresponding to the other circuit boards 23a. This is because, unlike other devices, the position of the biometric sensor 5 in the thickness direction of the antenna device 1 needs to be determined separately so that its surface 5a is approximately the same as the surface 21a of the core layer 21, which is the surface of the antenna device 1.

7(c), the spacer 24 is placed so as to overlap the circuit board 23 with the various devices bonded and fixed with the adhesive 50. The spacer 24 is provided with through holes or notches as necessary to avoid interference with the various devices protruding from the circuit board 23 on the opposite side to the core layer 22. The spacer 24 may be temporarily fixed to the circuit board 23 via the adhesive so that the placement position of the spacer 24 does not shift relative to the circuit board 23.

Also, before or after this, in order to ensure an electrical connection path between the circuit board 23b for the bioinformation sensor 5, which is arranged separately from the other circuit board 23a, and the circuit board 23a, a connecting wiring portion 23c, which is a conductive bridge element, is provided across the circuit boards 23a and 23b. The connecting wiring portion 23c may be a conductor, a copper piece, solder, or a conductive paste.

(v) Applying Adhesive to Substrate Next, as shown in Fig. 8(a), a core layer 21 is prepared as the substrate 2 that forms the surface of the antenna device 1 opposite to the core layer 22. A hole corresponding to the size of the surface 5a of the biometric sensor 5 is pre-opened in the core layer 21 so that the surface 5a of the biometric sensor 5 is exposed on the surface of the antenna device 1. A frame 21b is fixed by adhesive or the like to the surface of the core layer 21 that faces the circuit board 23 on the outer periphery of the hole. The frame 21b is a dam frame formed in the core layer 21 of the antenna device 1 filled with adhesive 40, and prevents the adhesive 40 from protruding out of the hole corresponding to the biometric sensor 5 before hardening.

Furthermore, after placing the core layer 21 with the frame 21b attached as described above on the same surface as the frame 21b, i.e., on the circuit board 23, a liquid adhesive 40 is applied to the opposite surface. The core layer 22 and the core layer 21 sandwich the RF communication circuit 3 and control circuit 4, which are the circuit board 23 on which various devices are mounted, to form the antenna device 1. Here, by sandwiching the adhesive 40 between them, the positions of the devices and circuit board 23 are fixed inside the antenna device 1 without misalignment, and the amount of exposure of the devices and circuit board 23 to the air is reduced, thereby suppressing their deterioration.

However, instead of applying the adhesive 40 to one side of the core layer 21 as in this embodiment, the adhesive 40 may be applied directly to the exposed surfaces of the various devices and the circuit board 23. This is because when the core layer 21 is finally laminated to the circuit board 23, the adhesive 40 will still fill the gaps between the core layers 21 and 22, excluding the various devices, the circuit board 23, and the spacer 24.

8(b), the core layer 21 coated with the adhesive is laminated on the intermediate laminate including the core layer 22, the circuit board 23 on which various devices are mounted, and the spacer 24, so that the adhesive-coated surface faces the circuit board 23. The final laminate including the core layer 21 laminated on the intermediate laminate is sandwiched between rollers from the front and back sides and conveyed, for example, to apply an appropriate load to make the thickness uniform, and is heated to room temperature or a predetermined temperature to promote hardening of the liquid adhesive filled inside.

(vii) Completion of the antenna device by punching out the laminate Although not shown, when the antenna device 1 is manufactured as a multi-sided laminate, the final laminate is punched out into a card shape to complete each antenna device 1. For punching, for example, a male-female blade or a Thomson blade (a V-blade) may be used as a punching die, or the card shape may be finished by cutting the outer periphery with laser irradiation.

(f) Regarding the First Embodiment The antenna device 1 mainly includes an RF communication circuit 3 including an RF chip 31, an RF antenna 32, and a switch circuit 34, and a control circuit 4 including a control chip 41 or a power supply unit 6, a control antenna 42, and a switch circuit 44. Although not an essential requirement of the antenna device 1, the antenna device 1 of the first embodiment further includes a biometric sensor 5 and has a card shape.

The antenna device 1 has its control circuit 4 in an active mode. As a result, electromagnetic waves of a specific frequency emitted from an external device such as a reader are received by the control antenna 42 of the control circuit 4, and the current generated by the electromotive force of electromagnetic induction can be stored in the power supply unit 6 or supplied to the control chip 41. At this time, the current can also be supplied to the biometric information sensor 5, allowing the control chip 41 and the biometric information sensor 5 to operate continuously. Therefore, the antenna device 1 can acquire the biometric information of the user by the biometric information sensor 5, and the control chip 41 can authenticate the user by comparing the acquired information with previously registered information, etc.

In addition, when certain conditions are met, such as when the control chip 41 of the antenna device 1 authenticates the user as a legitimate user, the RF communication circuit 3 goes into an active mode. As a result, electromagnetic waves of a specific frequency emitted from an external device such as a reader are received by the RF antenna 32 of the RF communication circuit 3, and a current generated by the electromotive force of electromagnetic induction is supplied to the RF chip 31, enabling contactless communication between the external device and the RF communication circuit 3 by transmitting and receiving electromagnetic waves.

At this time, the control unit of the control chip 41 switches the switch 35 of the switch circuit 34 of the RF communication circuit 3 and the switch 45 of the switch circuit 44 of the control circuit 4 to enable either the RF antenna 32 or the control antenna 42 and disable the other. In other words, the antenna device 1 can set either the RF communication circuit 3 or the control circuit 4 to an active mode, and at this time the other is in a deactivated mode.

By being provided with the above-described configuration and action, the antenna device 1 of the first embodiment can suppress the concentration of power consumption in the device as a whole, compared to a device that simultaneously secures both the power acquisition function and the non-contact communication function using all or part of the same antenna, and can reduce the possibility of unintended power acquisition and interruption of non-contact communication due to power shortage, and chip malfunction or failure due to power drop. Also, compared to a device that uses all or part of the same antenna and shifts the timing of use of the power acquisition function and the non-contact communication function, it can reduce the possibility that noise in the current and voltage signals will adversely affect (malfunction, etc.) the other function when one function is being used via the same antenna.

Furthermore, by being provided with the above-mentioned configuration and action, the antenna device 1 of the first embodiment can relatively easily adjust various parameters when enabling or disabling a specific antenna. That is, the resonant frequency of the RF communication circuit 3 of the antenna device 1 is determined primarily by the capacitor 33 and the adjustment capacitor 36 provided in the switch circuit 34, as shown in the above formula (the capacitance of the RF chip 31, etc., should also be taken into consideration, but this will be omitted here for simplicity's sake). Here, depending on whether the switch 35 of the switch circuit 34 is opened or closed, the capacitance component as viewed from the equivalent circuit of the RF communication circuit 3 can be easily changed to either the capacitance of the capacitor 33 alone or the combined capacitance of the capacitors 33 and 36.

In addition, the resonant frequency of the RF communication circuit 3 can be easily changed to two different states based on the capacitance that changes depending on the state of the switch 35. As a result, by simply selecting a combination of the capacitances of the capacitors 33 and 36 such that the RF communication circuit 3 resonates with electromagnetic waves of a predetermined frequency in one state and does not resonate in the other state for two different states of the resonant frequency of the RF communication circuit 3, it is possible to configure an RF communication circuit 3 that can easily enable and disable the RF antenna 32. Therefore, compared to a method that simply cuts off the current without shifting the resonant frequency of the antenna circuit, malfunctions due to the switching characteristics of the switch 35 can be suppressed.

For example, if a transistor that is a contactless switch is used for switch 35, even if it is open and the gate voltage is lowered, a small amount of leakage current may flow from the source to the drain, and if the resonant frequency is not shifted, the antenna circuit may operate inadvertently. Furthermore, there is no need to newly install a special communication circuit between the RF chip 31 and the control chip 41, and the RF chip 31 can be selected regardless of the function of the control chip 41, which expands the range of chip selection and simplifies circuit design.

2. Modification of the First Embodiment A modification of the antenna device 1 of the first embodiment will be described. Note that since the member configuration and circuit configuration of the antenna device are similar to those of the antenna device 1 of the first embodiment, the same reference numerals will be used to describe the differences.

(a) Modification 1
(i) Switch Circuit of RF Communication Circuit In the first modification, similarly to the first embodiment, the equivalent circuit of the RF communication circuit 3 is arranged as a parallel circuit of a coil with an inductance of _L1 and a capacitor with a capacitance of _C1 . In addition, the resonant frequency _f0 when the RF communication circuit 3 is activated is _f0 = ₁ /(2π × ( _L1C1 ) ^1/2 ).

The switch circuit 34 has a switch function for selecting whether to tune the resonant frequency of the RF communication circuit 3 to a predetermined frequency or to shift it, but the operation of the switch 35 is the opposite logic to that of the switch circuit 34 in the first embodiment. That is, when the switch 35 is closed, the RF communication circuit 3 is in the active mode, and the adjustment capacitor 36 is connected in parallel within the RF communication circuit 3.

At this time, the capacitances of the adjustment capacitor 36 and the tuning capacitor 33 connected outside the switch circuit 34 are selected so that the capacitance of the entire RF communication circuit 3 becomes _C1 , which is the capacitance of the above-mentioned equivalent circuit. In addition, the resonant frequency of the RF communication circuit 3 becomes _f0 , which is approximately the same as the frequency used for transmitting and receiving with an external device, for example, 13.56 MHz, and communication between the external device and the antenna device 1 is performed satisfactorily. Therefore, the RF antenna 32 is enabled, and the non-contact communication function of the RF communication circuit 3 is activated.

On the other hand, when the switch 35 is open, the RF communication circuit 3 is in the inactive mode. The tuning capacitor 36 is in a floating state within the RF communication circuit 3, and even if a current flows through the RF antenna 32, the tuning capacitor 36 is not charged, and the circuit characteristics of the RF antenna 32 are hardly affected. At this time, the capacitance of the entire RF communication circuit 3 mainly depends on the capacitance of the tuning capacitor 33, and the capacitance of the capacitor 33 is selected so that the capacitance of the equivalent circuit when this is added with the capacitance components of the other elements in the circuit is _{C12. Therefore, the resonant frequency of the RF communication circuit 3 shifts to f12 ,} which is larger than the above-mentioned _f0 .

When _f12 falls outside a predetermined range where good communication can be ensured, i.e., when the value of _f12 / _f0 is greater than 1.05, it is difficult to perform good communication between the external device and the antenna device 1, so the RF antenna 32 is disabled and the non-contact communication function of the RF communication circuit 3 is deactivated. Therefore, when it is desired to disable the RF antenna 32, communication due to an unintended malfunction of the RF communication circuit 3 can be suppressed, and noise generation or malfunction in the control circuit 4 due to simultaneous operation with the RF communication circuit 3 and operation interruption due to power shortage can be suppressed. In addition, it is more preferable that the value of _f22 / _f0 is greater than 1.1 in order to further enhance the effect of the suppression.

In addition, if the induced voltage induced in the RF communication circuit 3 by the received electromagnetic waves drops significantly, the RF antenna 32 is disabled and the non-contact communication function of the RF communication circuit 3 is deactivated, as in the first embodiment described above, so a detailed description of this point will be omitted.

(ii) Switch Circuit of Control Circuit The switch circuit 44 of the control circuit 4 can also have a configuration similar to that of the switch circuit 34 of the RF communication circuit 3 according to the above-mentioned modified example. That is, the equivalent circuit of the control circuit 4 is arranged to be a parallel circuit of a coil with an inductance of _L2 and a capacitor with a capacitance of _C2 . In addition, the resonant frequency _f0 when the control circuit 4 is activated is _f0 = ₁ /(2π × ( _L2C2 ) ^1/2 ).

When the switch 45 of the switch circuit 44 is closed, the control circuit 4 is in the active mode. As a result, the adjustment capacitor 46 is connected in parallel within the control circuit 4. At this time, the capacitances of the capacitor 46 and the tuning capacitor 43 connected outside the switch circuit 44 are selected so that the capacitance of the entire control circuit 4 becomes _C2 , which is the capacitance of the equivalent circuit described above.

On the other hand, when the switch 45 is open, the control circuit 4 is in the inactive mode. As a result, the adjustment capacitor 46 is in a floating state in the control circuit 4, and even if a current flows through the control antenna 42, the adjustment capacitor 46 is not charged, and the circuit characteristics of the control antenna 42 are hardly affected. At this time, the capacitance of the entire control circuit 4 mainly depends on the capacitance of the tuning capacitor 43, and the capacitance of the capacitor 43 is selected so that the capacitance of the equivalent circuit when this is added to the capacitance components of other elements in the circuit is _C22 , which is smaller than _C2 . Therefore, the resonant frequency of the control circuit 4 shifts to _f22 , which is larger than the above-mentioned _f0 .

When _f22 falls outside a predetermined range where good communication can be ensured, that is, when the value of _f22 / _f0 is greater than 1.05, it is difficult to perform good communication between the external device and the antenna device 1, so the control antenna 42 is disabled and the power acquisition function of the control circuit 4 is deactivated. Therefore, when it is desired to disable the control antenna 42, communication due to an unintended malfunction of the control circuit 4 is suppressed, and noise generation or malfunction in the control circuit 4 due to simultaneous operation with the RF communication circuit 3 and the control circuit 4, operation interruption due to power shortage, etc. are suppressed. In addition, it is more preferable that the value of _f12 / _f0 is greater than 1.1 in order to further enhance the effect of the suppression.

In addition, if the induced voltage induced in the control circuit 4 by the received electromagnetic waves drops significantly, the control antenna 42 is disabled and the power acquisition function of the control circuit 4 is deactivated, as in the first embodiment described above, so a detailed description of this point will be omitted.

(iii) Operation, etc., of the Antenna Device and Manufacturing Method The operation method, operation, and action of the antenna device 1 according to the modified example are generally similar to those of the above-described antenna device 1. However, step S203 needs to be interpreted as instructing the switches 35 and 45 to keep the switch 35 of the switch circuit 34 of the RF communication circuit 3 open and to close the switch 45 of the switch circuit 44 of the control circuit 4.

Similarly, in step S209, if biometric authentication is successful, the control chip 41 switches the switch 45 of the switch circuit 44 of the control circuit 4 from closed to open via the control unit 48. Also, at the same time, or after a certain time has elapsed after the switching of the switch 45, this should be interpreted as instructing the switches 35 and 45 to switch the switch 35 of the switch circuit 34b of the RF communication circuit 3 from open to closed.

Furthermore, step S213 should be interpreted as meaning that if the predetermined condition is not met (e.g., if the time exceeds 10 minutes), the control chip 41 switches the switch 35 of the switch circuit 34 of the RF communication circuit 3 from closed to open via the control unit 48, and keeps the switch 45 of the switch circuit 44 of the control circuit 4 open. In addition, the manufacturing method of the antenna device 1 is the same as that of the antenna device 1 described above.

In this modification, an equivalent circuit of an RF communication circuit 3B is assumed in which the coil inductance _L1 in the equivalent circuit of the RF communication circuit 3 described above is replaced with _L5 , the capacitance _C1 with _C5 , and the resonance frequency _f1 with _f5 . Here, when the switch 35 of the switch circuit 34b of the RF communication circuit 3B is closed, the RF antenna 32, the switch circuit 34b, and the RF chip 31 form a closed circuit, to which the capacitor 33 is connected in parallel. The capacitance of the entire RF communication circuit 3B mainly depends on the capacitance of the capacitor 33, and the capacitance of the capacitor 33 is selected so that the combined capacitance of the capacitor 33 and the capacitance of the other elements in the circuit is _C5, which is the capacitance of the equivalent circuit described above.

Therefore, at this time, the resonant frequency _f5 of the RF communication circuit 3B is substantially the same as the frequency used for transmitting and receiving with the external device, for example, 13.56 MHz, and communication between the external device and the antenna device 1B is performed satisfactorily. In this case, the RF antenna 32 is enabled, and the non-contact communication function of the RF communication circuit 3A is activated.

On the other hand, when switch 35 is open, the wiring toward end 32a of RF antenna 32 is essentially disconnected and is not electrically connected to RF chip 31. Therefore, RF communication circuit 3B does not form a closed circuit including RF antenna 32 and RF chip 31, and even if an AC magnetic field is generated at both ends of RF antenna 32, the current and voltage are not input to RF chip 31. Therefore, in this case, RF antenna 32 is clearly disabled, and the non-contact communication function of RF communication circuit 3A is deactivated.

(b) Modification 2
As described above, in the first modification, when the switch 35 of the switch circuit 34 of the RF communication circuit 3 is closed, the resonant frequency of the RF communication circuit 3 is tuned to a predetermined frequency to activate the RF communication circuit 3, and when the switch 35 is opened, the resonant frequency of the RF communication circuit 3 is shifted from the predetermined frequency to deactivate the RF communication circuit 3. Similarly, when the switch 45 of the switch circuit 44 of the control circuit 4 is closed, the resonant frequency of the control circuit 4 is tuned to a predetermined frequency to activate the control circuit 4, and when the switch 35 is opened, the resonant frequency of the control circuit 4 is shifted from the predetermined frequency to deactivate the control circuit 4.

In contrast, in the second modification, the switch circuit of one of the antenna circuits of the RF communication circuit 3 and the control circuit 4 has a configuration in which the antenna circuit is activated when the switch is open, i.e., the configuration of the first embodiment, and the switch circuit of the other antenna circuit has a configuration in which the antenna circuit is activated when the switch is closed, i.e., the configuration of the first modification. For example, in the switch circuit 34 of the RF communication circuit 3, the capacitance of the capacitor 33 is selected so that when the switch 35 is open, the capacitance of the entire RF communication circuit 3 becomes _C1, which is the capacitance of the equivalent circuit described above. Therefore, at this time, the resonant frequency of the RF communication circuit 3 becomes _f0 .

Furthermore, when the switch 35 is closed, the capacitance of the entire RF communication circuit 3 shifts to _C11, which is a capacitance larger than _C1 . Therefore, the resonant frequency of the RF communication circuit 3 shifts to _f11 , which is smaller than the above-mentioned _f0 .

On the other hand, in the switch circuit 44 of the control circuit 4, the capacitances of the capacitor 46 and the tuning capacitor 43 connected to the outside of the switch circuit 44 are selected so that the capacitance of the entire control circuit 4 becomes _C2, which is the capacitance of the equivalent circuit described above, when the switch 45 is closed.

Furthermore, when the switch 45 is open, the capacitance of the entire control circuit 4 mainly depends on the capacitance of the tuning capacitor 43, and the capacitance of the capacitor 43 is selected so that the capacitance of the equivalent circuit obtained by adding this and the capacitance components of the other elements in the circuit is _C22, which is smaller than _C2 . Therefore, the resonant frequency of the control circuit 4 shifts to _f22 , which is larger than the above-mentioned _f0 .

In this way, in the second modification, the resonant frequencies of the antenna circuit when the RF communication circuit 3 and the control circuit 4 are both activated are _f0 , but when the RF communication circuit 3 is deactivated, the resonant frequency of the RF communication circuit 3 shifts to _f11 which is smaller than _f0 , and when the control circuit 4 is deactivated, the resonant frequency of the control circuit 4 shifts to _f22 which is larger than _f0 . Therefore, even if there is a certain range of the activatable frequencies _f0 of the RF communication circuit 3 and the control circuit 4 of the antenna device 1 and the frequency of the electromagnetic waves transmitted from an external device such as a reader fluctuates slightly above and below _f0 , it is possible to further reduce the possibility that the RF communication circuit 3 and the control circuit 4, whose switch circuits have been switched so that one of them is deactivated, are erroneously activated at the same time.

Conversely, the antenna device 1 may be configured so that when the RF communication circuit 3 is deactivated, the resonant frequency of the RF communication circuit 3 shifts to _f12, which is greater than _f0 , and when the control circuit 4 is deactivated, the resonant frequency of the control circuit 4 shifts to _f21, which is less than _f0 .

(c) Modification 3
The manufacturing method of the antenna device 1 of this embodiment is not limited to the above. An example of the configuration and manufacturing method of the antenna device 1D according to the modified example 3 will be described below. Fig. 12 is a cross-sectional view of the antenna device 1D of the modified example 3 corresponding to Fig. 2, and Fig. 13 is a diagram illustrating the manufacturing process of the antenna device 1D corresponding to Fig. 8.

The antenna device 1D of the third modification is different from the antenna device 1 in that, as shown in FIG. 12, the circuit board 23 is not fixed to the core layer 22 by the adhesive 50. Instead, the circuit board 23 is fixed to the core layer 21 via the adhesive 50 provided around the biometric sensor 5. That is, the adhesive 50 is attached so as to surround the periphery of the frame 21b on the back surface of the core layer 21 facing the circuit board 23, and the core layer 21 and the circuit board 23 are abutted against one end of the adhesive 50 in the thickness direction, and against the other end. This allows the adhesive 50 to be used in fewer places than in the antenna device 1, and the amount of adhesive used can be reduced.

When manufacturing the antenna device 1D of the third modification, first, as shown in FIG. 13(a), a core layer 21 is prepared, and a hole is opened in advance according to the size of the surface 5a of the biometric sensor 5 so that the surface 5a of the biometric sensor 5 is exposed on the surface of the antenna device 1. A frame 21b is fixed with an adhesive or the like to the surface of the core layer 21 facing the circuit board 23 on the outer periphery of the hole. Furthermore, an adhesive material 50 of the same size or slightly larger than the frame 21b is adhered to the frame 21b along the frame 21b of the core layer 21. A part of the adhesive material 50 may be directly adhered to the core layer 21 outside the frame 21b.

Next, as shown in FIG. 13(b), the core layer 21 with the adhesive 50 attached is laminated onto the circuit board 23 on which various devices are mounted, and the end of the adhesive 50 is pressed against a part of the circuit board 23. Note that the spacer 24 is placed on the circuit board 23 in advance. This fixes the relative positions of the various devices, circuit board 23, spacer 24, and core layer 21, preventing significant misalignment.

Then, as shown in FIG. 13(b), the core layer 22 is placed on the surface of the circuit board 23 opposite the core layer 21 with a certain distance therebetween. Furthermore, the adhesive 40 is then injected and filled into the entire gap between the core layer 21 and the core layer 22, and the adhesive is allowed to harden. This completes the antenna device 1D according to the third modification, which has a configuration substantially similar to that of the antenna device 1, except for the placement of the adhesive 50.

As a result, in variant example 3, by providing adhesive 50 in an area along frame 21b of core layer 21, it is possible to temporarily fix circuit board 23 and core layer 21, thereby simplifying the process and reducing the amount of adhesive 50 used.

3. Second embodiment of the present disclosure Next, an antenna device 1A of a second embodiment will be described, focusing mainly on the differences from the first embodiment. Fig. 9 is a diagram showing a schematic circuit of the antenna device 1A of the second embodiment, corresponding to Fig. 3. The antenna device 1A includes an RF communication circuit 3A and a control circuit 4A. The RF communication circuit 3A and the control circuit 4A also include switch circuits 34a and 44a that are different from the switch circuits 34 and 44 included in the RF communication circuit 3 and the control circuit 4 of the antenna device 1, respectively.

Both switch circuits 34 and 34a are connected in parallel across the wiring leading to end 32a and the wiring leading to end 32b of RF antenna 32. However, they differ in that while switch circuit 34 is configured with switch 35 and adjustment capacitor 36 connected in series, switch circuit 34a is composed only of switch 35. The same is true of switch circuit 44a of control circuit 4A.

(a) Switching Circuit of RF Communication Circuit Let us assume an equivalent circuit of an RF communication circuit 3A in which the coil inductance _L1 in the equivalent circuit of the RF communication circuit 3 described above is replaced with _L3 , the capacitance _C1 with _C3 , and the resonance frequency _f1 with _f3 . Here, when the switch 35 of the switching circuit 34a of the RF communication circuit 3A is open, the RF communication circuit 3A is in the active mode. The capacitance of the entire RF communication circuit 3A mainly depends on the capacitance of the capacitor 33, and the capacitance of the capacitor 33 is selected so that the combined capacitance of this and the capacitance components of the other elements in the circuit is _C3, which is the capacitance of the equivalent circuit described above.

At this time, the resonant frequency _f3 of the RF communication circuit 3A is substantially the same as the frequency used for transmitting and receiving with the external device, for example, 13.56 MHz, and communication between the external device and the antenna device 1A is performed satisfactorily. In this case, the RF antenna 32 is enabled, and the non-contact communication function of the RF communication circuit 3A is activated.

On the other hand, when switch 35 is closed, RF communication circuit 3A is in a deactivated mode. As both ends of capacitor 33, which is connected in parallel to switch circuit 34a, are at the same voltage, the capacitor is unable to perform its storage function. Also, as the wiring leading to end 32a of RF antenna 32 and the wiring leading to end 32b are shorted, no AC magnetic field is generated at both ends of RF antenna 32. Therefore, in this case, RF antenna 32 is clearly disabled, and the non-contact communication function of RF communication circuit 3A is deactivated.

(b) Switch circuit of the control circuit The operation of the switch circuit 44a of the control circuit 4A is similar to that of the switch circuit 34a of the RF communication circuit 3A described above. Let us assume an equivalent circuit of the control circuit 4A in which the coil inductance _L2 in the equivalent circuit of the control circuit 4 described above is replaced with _L4 , the capacitance _C2 with _C4 , and the resonance frequency _f2 with _f4 . Here, when the switch 45 of the switch circuit 44a is open, the control circuit 4A is in an active mode. The capacitance of the capacitor 43 is selected so that the combined capacitance of the capacitor 43 and the capacitance components of the other elements in the circuit is _C4 , which is the capacitance of the equivalent circuit described above, so that the control antenna 42 is enabled and the non-contact communication function of the control circuit 4A is activated.

On the other hand, when switch 45 is closed, control circuit 4A is in a deactivated mode. At this time, capacitor 43 is unable to perform its storage function, and no AC magnetic field is generated across control antenna 42. In this case, control antenna 42 is clearly disabled, and the power acquisition function of control circuit 4A is inactivated.

(c) Operation, etc., of the Antenna Device and Manufacturing Method The operating method, operation, and effects of the antenna device 1A are the same as those of the previously described antenna device 1. In addition, the manufacturing method of the antenna device 1A is also the same as those of the previously described antenna device 1.

(d) Regarding the Second Embodiment The antenna device 1A differs from the antenna device 1 of the first embodiment in the configuration of a switch circuit 34a that selects whether to enable or disable the RF antenna 32 provided in the RF communication circuit 3A, and a switch circuit 44a that selects whether to enable or disable the control antenna 42 provided in the control circuit 4A. In this embodiment, the switch circuit 34a has only a switch 35, and does not have a capacitor connected in series as in the switch circuit 34 of the first embodiment.

Therefore, when the switch 35 is opened, the RF communication circuit 3 enters the activation mode by the same action as in the first embodiment. At this time, electromagnetic waves of a specific frequency emitted from an external device such as a reader are received by the RF antenna 32 of the RF communication circuit 3A, and a current generated by the electromotive force of electromagnetic induction is supplied to the RF chip 31, and non-contact communication by transmitting and receiving electromagnetic waves between the external device and the RF communication circuit 3A becomes possible.

On the other hand, when the switch 35 is closed, the RF communication circuit 3 goes into the inactive mode, but the content is different from that of the first embodiment. That is, the resonant frequency of the RF communication circuit 3A does not fluctuate compared to when the switch 35 is open, and the RF antenna 32 is disabled by shorting both ends of the RF antenna 32 and the capacitor 33, essentially cutting off the generation of current. The same applies to the switch circuit 44a of the control circuit 4A.

As described above, in this embodiment, the configuration of the switch circuits 34a and 44a can be simplified while controlling the enabling and disabling of the RF antenna 32 and the control antenna 42. Note that whether the switch 35 is a contact switch or a non-contact switch, the impedance across the switch 35 may not necessarily be zero when the switch 35 is closed.

At this time, even if the switch 35 is closed, a small amount of current may still flow into the control circuit 4A. Therefore, it is preferable to provide some kind of operation restriction circuit in the RF chip 31 or the RF communication circuit 3A so that the RF chip 31 will not start operating unless a certain amount of current or voltage is generated in the antenna circuit.

4. Third embodiment of the present disclosure Next, an antenna device 1B of a third embodiment will be described, focusing mainly on the differences from the first embodiment, as in the second embodiment. Fig. 10 is a diagram showing a schematic circuit of the antenna device 1B of the third embodiment, corresponding to Fig. 3. The antenna device 1B includes an RF communication circuit 3B and a control circuit 4B.

Furthermore, the RF communication circuit 3B and the control circuit 4B have switch circuits 34b and 44b that are different from those of the antenna devices 1 and 1A. Furthermore, the positions of the switch circuits 34b and 44b are also different from those of the switch circuits 34, 34a and 44, 44a. The same is true of the switch circuit 44a of the control circuit 4A.

(a) Switch circuit of RF communication circuit The switch circuits 34 and 34a of the RF communication circuits 3 and 3A of the first and second embodiments are connected in parallel across the wiring toward the end 32a and the wiring toward the end 32b of the RF antenna 32. However, the switch circuit 34b of the RF communication circuit 3B of the third embodiment is connected in series to the wiring toward the end 32a of the RF antenna 32. The switch circuit 34b may be connected in series to the wiring toward the end 32b of the RF antenna 32. Furthermore, the switch circuit 34b is composed of only a switch 35, similar to the switch circuit 34a of the second embodiment. The same is true of the switch circuit 44b of the control circuit 4B.

Assume an equivalent circuit of an RF communication circuit 3B in which the coil inductance _L1 in the equivalent circuit of the RF communication circuit 3 described above is replaced with _L5 , the capacitance _C1 with _C5 , and the resonance frequency _f1 with _f5 . Here, when the switch 35 of the switch circuit 34b of the RF communication circuit 3B is closed, the RF communication circuit 3B is in an active mode. At this time, the RF antenna 32, the switch circuit 34b, and the RF chip 31 form a closed circuit, to which the capacitor 33 is connected in parallel. The capacitance of the entire RF communication circuit 3B mainly depends on the capacitance of the capacitor 33, and the capacitance of the capacitor 33 is selected so that the capacitance obtained by adding the capacitance of the capacitor 33 and the capacitance of the other elements in the circuit is _C5, which is the capacitance of the equivalent circuit described above.

Therefore, the resonant frequency _f5 of the RF communication circuit 3B is substantially the same as the frequency used for transmitting and receiving with the external device, for example, 13.56 MHz, and communication between the external device and the antenna device 1B is performed satisfactorily. In this case, the RF antenna 32 is enabled, and the non-contact communication function of the RF communication circuit 3A is activated.

On the other hand, when switch 35 is open, RF communication circuit 3B is in a deactivated mode. At this time, the wiring toward end 32a of RF antenna 32 is essentially disconnected, and is not electrically connected to RF chip 31. Therefore, RF communication circuit 3B does not form a closed circuit including RF antenna 32 and RF chip 31, and even if an AC magnetic field is generated at both ends of RF antenna 32, the current and voltage are not input to RF chip 31. Therefore, in this case, RF antenna 32 is clearly disabled, and the non-contact communication function of RF communication circuit 3A is inactivated.

(b) Switch circuit of the control circuit The operation of the switch circuit 44b of the control circuit 4B is similar to that of the switch circuit 34b of the RF communication circuit 3B described above. Let us assume an equivalent circuit of the control circuit 4B in which the coil inductance _L2 in the equivalent circuit of the control circuit 4 described above is replaced with _L6 , the capacitance _C2 with _C6 , and the resonance frequency _f2 with _f6 . Here, when the switch 45 of the switch circuit 44b is closed, the control circuit 4B is in an active mode. Here, the capacitance of the capacitor 43 is selected so that the combined capacitance of the capacitor 43 and the capacitance components of the other elements in the circuit is _C6, which is the capacitance of the equivalent circuit described above, so that the control antenna 42 is enabled and the non-contact communication function of the control circuit 4B is activated.

On the other hand, when the switch 45 is open, the control circuit 4B is in a deactivated mode. At this time, even if an AC magnetic field is generated at both ends of the control antenna 42, the current and voltage are not input to the control chip 41 or the power supply unit 6. In this case, the control antenna 42 is apparently disabled, and the power acquisition function of the control circuit 4B is in a deactivated state.

In this way, the switch circuit 34b of the RF communication circuit 3B of the third embodiment reverses the behavior of enabling or disabling the RF antenna 32 and activating or deactivating the RF communication circuit 3B, which is determined depending on whether the switch 35 is open or closed. That is, in the switch circuits 34 and 34a of the RF communication circuits 3 and 3A of the first and second embodiments, when the switch 35 is open, the RF antenna 32 is enabled and the RF communication circuits 3 and 3A are activated, but in the switch circuit 34b of the RF communication circuit 3B of the third embodiment, when the switch 35 is open, the RF antenna 32 is disabled and the RF communication circuit 3B is deactivated.

(c) Operation, etc., of the Antenna Device and Manufacturing Method The operation method, operation, and action of the antenna device 1A are generally similar to those of the antenna device 1 described above. However, step S203 should be interpreted as instructing the switches 35 and 45 to keep the switch 35 of the switch circuit 34b of the RF communication circuit 3B open and to close the switch 45 of the switch circuit 44b of the control circuit 4B. Similarly, in step S209, when biometric authentication is successful, the control chip 41 switches the switch 45 of the switch circuit 44b of the control circuit 4B from closed to open via the control unit 48.

In addition, at the same time, or after a certain time has elapsed after the switching of switch 45, it should be interpreted as instructing switches 35 and 45 to switch switch 35 of switch circuit 34b of RF communication circuit 3B from open to closed.

Furthermore, step S213 should be interpreted as meaning that if a predetermined condition is not met (e.g., if the time exceeds 10 minutes), the control chip 41 switches the switch 35 of the switch circuit 34b of the RF communication circuit 3B from closed to open via the control unit 48, and keeps the switch 45 of the switch circuit 44b of the control circuit 4 open. The manufacturing method of the antenna device 1B is the same as that of the antenna device 1 described above.

(d) Regarding the third embodiment The antenna device 1B differs from the antenna device 1 of the first embodiment in the configuration of the switch circuit 34b that selects whether to enable or disable the RF antenna 32 provided in the RF communication circuit 3B and the switch circuit 44b that selects whether to enable or disable the control antenna 42 provided in the control circuit 4B, and also in the arrangement of the switch circuits 34b and 44b in the RF communication circuit 3B and the control circuit 4B. In this embodiment, the switch circuit 34b has only the switch 35 as in the second embodiment, and does not have a capacitor in series like the switch circuit 34 of the first embodiment. Furthermore, the switch circuit 34b of the RF communication circuit 3B has a configuration in which it is connected in series in the middle of the wiring toward the end 32a of the RF antenna 32 or in the middle of the wiring toward the end 32b.

Therefore, the behavior of the RF antenna 32 and the RF communication circuit 3B is reversed when the switch 35 is open and when it is closed. In other words, when the switch 35 is closed, the same action as in the first embodiment causes electromagnetic waves of a predetermined frequency emitted from an external device such as a reader to be received by the RF antenna 32 of the RF communication circuit 3B, and a current generated by the electromotive force of electromagnetic induction is supplied to the RF chip 31, and non-contact communication by transmitting and receiving electromagnetic waves can be performed between the external device and the RF communication circuit 3B.

On the other hand, when the switch 35 is opened, unlike the first embodiment, the resonant frequency of the RF communication circuit 3B does not fluctuate compared to when the switch 35 is closed, and one end of the RF antenna 32 is disconnected or pseudo-disconnected, causing it to lose connection with the RF chip 31, thereby essentially cutting off the generation of current and disabling the RF antenna 32. The same is true for the switch circuit 44b of the control circuit 4B.

As described above, in this embodiment, the configuration of the switch circuits 34b and 44b can be simplified while controlling the enabling and disabling of the RF antenna 32 and the control antenna 42. Note that if the switch 35 is a non-contact switch, even if the switch 35 is open, i.e., the gate voltage of a transistor or the like is lowered below the operating voltage, a small amount of leakage current may flow from the source to the drain, and as a result, a small amount of current may flow in the control circuit 4B. Therefore, it is preferable to provide some kind of operation restriction circuit in the RF chip 31 or the RF communication circuit 3B so that the RF chip 31 does not start operating unless a certain current or voltage is generated.

5. Fourth embodiment of the present disclosure Next, an antenna device 1C of a fourth embodiment will be described, focusing on the differences from the first embodiment. Fig. 11 is a plan view of a dual interface IC card, which is the antenna device 1C of the fourth embodiment, corresponding to Fig. 1. The dual interface IC card refers to an IC card that can share, on a single chip, a contact communication function that transmits and receives data to and from an external device such as a bank ATM machine via an external contact terminal, and a contactless communication function that transmits and receives data to and from an external device such as an automatic ticket gate wirelessly using electromagnetic waves or the like.

As shown in FIG. 11, the antenna device 1C includes a substantially rectangular substrate 2, an RF chip 31g having a substantially rectangular external contact terminal 31e arranged on the surface of the substrate 2, a substantially rectangular biometric sensor 5, a display unit 7, and a power switch 8, all of which can be seen directly. The components shown in dashed lines are arranged inside or at the back of the substrate 2 and therefore cannot be seen directly, but the antenna device 1C further includes an RF communication circuit 3 including the RF chip 31g and RF antenna 32, a control circuit 4 including a control chip 41, a control antenna 42, the biometric sensor 5, and a power supply unit 6.

The antenna device 1C receives electromagnetic waves of a specific frequency emitted from an external device such as a reader at the control antenna 42 of the control circuit 4, and can store the current generated by the electromotive force of electromagnetic induction in the power supply unit 6 or supply it to the control chip 41 and the biometric information sensor 5. The antenna device 1C also receives electromagnetic waves of a specific frequency emitted from an external device at the RF antenna 32 of the RF communication circuit 3, and can perform non-contact communication between the external device and the RF communication circuit 3 by transmitting and receiving electromagnetic waves.

Furthermore, the antenna device 1C can set either the RF communication circuit 3 or the control circuit 4 to an active mode in response to an instruction from the control unit 48 of the control chip 41, and at this time the other is always in an inactive mode. At this time, either the RF antenna 32 of the RF communication circuit 3 or the control antenna 42 of the control circuit 4 can be controlled to be activated and the other to be disabled. This makes it possible to avoid concentration of power consumption compared to when both functions are activated simultaneously, and suppresses adverse effects such as a current flowing through one of the antennas in use flowing to the other unused antenna.

Furthermore, the antenna device 1C can perform contact communication with an external device through the external contact terminal 31e at any time, independent of the above series of operations, by using the function of the RF chip 31g. In other words, while the control antenna 42 is enabled and the power acquisition function of the control circuit 4 is activated, the antenna device 1C is allowed to perform a series of operations based on the power acquisition function of the control circuit 4, such as the acquisition of biometric information by the biometric sensor 5 and judgment by the control chip 41, but the non-contact communication function of the RF communication circuit 3 cannot be used.

On the other hand, while the antenna device 1C has the RF antenna 32 enabled and the non-contact communication function of the RF communication circuit 3 activated, non-contact communication is permitted, but a series of operations based on the power acquisition function, such as acquisition of biometric information by the biometric sensor 5 or judgment by the control chip 41, cannot be performed.

However, regardless of whether the RF communication circuit 3 or the control circuit 4 is activated, the antenna device 1C can achieve a contact communication function conforming to ISO 7816 by contacting the external contact terminal 31e of the antenna device 1C with a contact pin of an external device based on the contact communication function of the RF chip 31g. However, since the RF chip 31g used in a dual interface IC card is usually designed to prioritize either non-contact communication or contact communication, it is often not possible to perform contact communication simultaneously during non-contact communication.

The RF chip 31g and the control chip 41 can also be connected by a signal line via the circuit board 23. In this case, the antenna device 1C can be controlled so that the contact communication function is not activated until the control circuit 4 is deactivated, just as the RF communication circuit 3 is not activated until the control circuit 4 is deactivated. For example, if user authentication using a series of biometric sensors 5 is not successful, not only the contact communication function but also the non-contact communication function can be disabled, thereby improving the security of the antenna device 1C.

(a) Configuration of RF communication circuit and control circuit The configuration of the RF communication circuit 3 and the control circuit 4 of the antenna device 1C is the same as that of the first embodiment except for the contact communication part. Also, as described above, the RF chip 31g and the control chip 41 may be electrically connected by a signal line.

(i) RF Chip The RF chip 31g has a contact communication interface in addition to the various functions related to contactless communication of the RF chip 31, and is surrounded by external contact terminals 31e having six or eight independent terminals conforming to ISO 7816. The RF chip 31g and the external contact terminals 31e may be manufactured as an integrated IC module, or the RF chip 31g alone may be formed on the circuit board 23 separately from the external contact terminals 31e, and the two may be electrically connected by a flexible board.

(ii) RF Antenna As in the first embodiment, the RF antenna 32 has two ends 32a and 32b, which are the starting and ending points of the RF antenna 32, connected to connection pads 31a and 31b, which are electrical connection terminals of the RF chip 31g, thereby forming a closed circuit with the RF chip 31g.

(b) Operation of the Antenna Device, etc. The operation method, operation, and action of the antenna device 1C are the same as those of the above-mentioned antenna device 1. However, as described above, control may be added to activate a contact communication function with an external device through the external contact terminal 31e of the RF chip 31g in conjunction with activation of the RF communication circuit 3 by the RF chip 31g or only under the condition that the RF communication circuit 3 is activated.

In this case, the decision as to whether to activate the contact communication function of the RF chip 31g may be made by the control chip 41, or the RF chip 31g may detect the activated or deactivated state of the non-contact communication function and decide for itself whether to activate the contact communication function. In this case, the conditions for activating the non-contact communication function and the conditions for activating the contact communication function may be controlled to be different.

(c) Manufacturing Method of Antenna Device The manufacturing method of antenna device 1C is almost the same as that of the above-mentioned antenna device 1. However, in the process of forming an antenna and attaching devices to circuit board 23, various devices including RF chip 31g are attached to one side of circuit board 23, but it is necessary that external contact terminal 31e, which is integrated with RF chip 31g or arranged separately and electrically connected thereto, is formed in advance.

In the process of applying adhesive to the substrate, at the stage of preparing the core layer 21 that forms the surface opposite to the core layer 22 of the antenna device 1C, a hole corresponding to the size of the surface 5a of the biometric sensor 5 is already drilled in the core layer 21 so that the surface 5a of the biometric sensor 5 is exposed on the surface of the antenna device 1. In addition, it is necessary to drill a hole corresponding to the size of the external contact terminal 31e in the core layer 21 so that the external contact terminal 31e is exposed on the surface of the antenna device 1C.

When the RF chip 31g is formed as an integrated IC module with the external contact terminal 31e, instead of following the above-mentioned method, a card-sized intermediate is manufactured by the manufacturing method of the antenna device 1 in the first embodiment using a circuit board 23 that does not mount the RF chip 31g. After that, the surface of the intermediate is machined along the intended mounting area of the external contact terminal 31e to form a recess, exposing both ends 32a and 32b of the RF antenna 32 on the circuit board 23.

After applying a conductive paste or the like to the upper surfaces of both ends 32a and 32b of the RF antenna 32, an IC module including the RF chip 31g is aligned and mounted so as to be electrically connected to the ends 32a and 32b of the RF antenna 32, and the conductive paste is heated and hardened. At this time, two terminals electrically connected to the connection pads 31a and 31b of the RF chip 31g are exposed on the IC module, and these two terminals are electrically connected to both ends 32a and 32b of the RF antenna 32, respectively. This can simplify the manufacturing process and improve yields, thereby reducing manufacturing costs.

(d) Regarding the Fourth Embodiment The antenna device 1C is a dual interface IC card equipped with an RF communication circuit 3 including an RF chip 31g and an RF antenna 32 capable of performing both contact communication and contactless communication on a single chip, and a control circuit 4 including a control chip 41 or a power supply unit 6 and a control antenna 42. The antenna device 1C may further include a biometric information sensor 5.

The antenna device 1C has all the functions of the antenna device 1, which is the card of the first embodiment described above. Furthermore, the antenna device 1C can perform contact communication with an external device via the external contact terminal 31e of the antenna device 1C based on the contact communication function of the RF chip 31g, regardless of whether the RF communication circuit 3 is activated or the control circuit 4 is activated. This allows the antenna device 1C to be used as a dual interface IC card, combining the functions of both contactless communication and contact communication.

In addition, when performing non-contact communication, which is relatively susceptible to unauthorized use such as skimming, it is easy to distinguish between the two, such as allowing communication only when safety has been confirmed in advance through biometric authentication, etc. Furthermore, if no communication circuit or the like is provided between the RF chip 31g and the control chip 41, the RF chip 31g can be selected regardless of the function of the control chip 41, which can expand the range of chip selection and facilitate circuit design.

The antenna device 1C may also be configured to transmit the power supply supplied through the external contact terminal 31e of the RF chip 31g to the control chip 41 of the control circuit 4 during contact communication. That is, a power supply wiring may be provided between the RF chip 31g and the control chip 41. In this way, the antenna device 1C can supply sufficient power to the control chip 41 and the biometric information sensor 5 while performing contact communication. As a result, when safety is confirmed through biometric authentication or the like, the RF communication circuit 3 is activated, enabling good non-contact communication.

In the first, second and third embodiments, the configuration of the switch circuit provided in each RF communication circuit and control circuit is illustrated as being the same. However, the present disclosure is not limited to this, and it goes without saying that an antenna device may be formed by combining a switch circuit provided in an RF communication circuit exemplified in any one of the embodiments or variants with a switch circuit provided in a control circuit exemplified in another embodiment or variant different from the above. The same is true for the dual interface IC card of the fourth embodiment, and all of these are included in the scope of the present disclosure.

1, 1A, 1B, 1D Antenna device 1C Antenna device (dual interface IC card)
2 Substrate 3, 3A, 3B RF communication circuit 4, 4A, 4B Control circuit 5 Bio-information sensor 6 Power supply unit 7 Display unit 8 Power switch 21, 22 Core layer 21a Surface 21b Frame 23, 23a, 23b Circuit board 23c Connecting wiring portion 24 Spacer 31, 31g RF chip 31a, 31b, 31c, 31d, 31f Connection pad 31e External contact terminal 32 RF antenna 32a, 32b End 33 Capacitor 34, 34a, 34b Switch circuit 35 Switch 35s Signal 36 Adjustment capacitor 37 Rectifier circuit 38 Field effect transistor 38s Signal 40 Adhesive 41 Control chip 41a, 41b Connection pad 41c, 41e Wiring 42 Control antenna 42a, 42b End 43 Capacitor 44, 44a, 44b Switch circuit 45 Switch 45s Signal 46 Adjustment capacitor 47 Rectifier circuit 48 Control unit 49 Memory 50 Adhesive material

Claims (13)

A first IC chip;
a first antenna capable of forming a closed circuit by being electrically connected to the first IC chip;
a first switch circuit that is arranged in series or in parallel with the closed circuit formed by the first IC chip and the first antenna and that can be switched to a first mode or a second mode; and
A second IC chip;
a second antenna capable of forming a closed circuit by being electrically connected to the second IC chip;
a second switch circuit that is arranged in series or in parallel with the closed circuit formed by the second IC chip and the second antenna and that can be switched to a third mode or a fourth mode;
In addition, it is equipped with a power supply unit,
In the first mode, the first circuit resonates with an electromagnetic wave of a predetermined frequency, and in the second mode, the first circuit does not resonate;
In the third mode, the second circuit resonates with the electromagnetic wave of the predetermined frequency, and in the fourth mode, the second circuit does not resonate.
When the first switch circuit is in the second mode, the second switch circuit can be switched to the third mode;
When the second switch circuit is in the fourth mode, the first switch circuit can be switched to the first mode ;
The first circuit is configured to generate a nonlinear effect by transmitting and receiving electromagnetic waves of the predetermined frequency in the first mode.
Contact communication is possible, and non-contact communication is difficult in the second mode;
The second circuit receives electromagnetic waves of the predetermined frequency in the third mode.
A current generated by magnetic induction electromotive force can be supplied to the power supply unit,
if a predetermined condition is not met, the first circuit is maintained in the second mode;
When the predetermined condition is satisfied, the second circuit is switched from the third mode to the fourth mode, and the first circuit is switched from the second mode to the first mode.
Antenna device. The antenna device includes a biological information sensor.
The predetermined condition is that the biometric information acquired by the biometric information sensor is compared with pre-registered information to determine whether or not the biometric information is being used by a legitimate user.
2. The antenna device according to claim 1. 3. The antenna device according to claim 2, wherein at least one of the first switch circuit and the second switch circuit has a switch and a capacitive element electrically connected in series, and the at least one switch circuit is arranged in parallel with the corresponding closed circuit. the first switch circuit and the second switch circuit are each configured such that the switch and the capacitive element are electrically connected in series, and both switch circuits are disposed in parallel with the corresponding closed circuit;
4. The antenna device according to claim 3 , wherein the capacitive element of the first switch circuit and the capacitive element of the second switch circuit have different capacitances. When the predetermined frequency is _f0 , the resonant frequency of the first circuit in the second mode is _f1 , and the resonant frequency of the second circuit in the fourth mode is _f2 ,
5. An antenna arrangement according to claim 3 or 4 , wherein the value of _f1 / _f0 or _f2 / _f0 is less than 0.9 or greater than 1.1. When the first circuit receives the electromagnetic wave of the predetermined frequency, an absolute value of the induced voltage in the first mode is defined as _V01 , and an absolute value of the induced voltage in the second mode is defined as _V1 ,
When the second circuit receives the electromagnetic wave of the predetermined frequency, the absolute value of the induced voltage in the third mode is _V02 and the absolute value of the induced voltage in the fourth mode is _V2 .
6. An antenna arrangement according to claim 3 , wherein the value of _V1 / _V01 or _V2 / _V02 is smaller than 0.5. at least one of the first switch circuit and the second switch circuit has only a switch electrically connected thereto;
3. The antenna device according to claim 2 , wherein a capacitive element is disposed in parallel in the closed circuit corresponding to any one of the switch circuits, and any one of the switch circuits is disposed in parallel with the capacitive element. When any one of the switch circuits is the first switch circuit,
When the switch of the first switch circuit is in an open state, the first circuit is in a first mode, and when the switch is in a closed state, the first circuit is in the second mode;
When any one of the switch circuits is the second switch circuit,
8. The antenna device according to claim 7 , wherein the second circuit is in the third mode when the switch of the second switch circuit is in an open state, and in the fourth mode when the switch is in a closed state. 3. The antenna device according to claim 2, wherein at least one of the first switch circuit and the second switch circuit has only a switch electrically connected thereto, and the at least one switch circuit is disposed in series with the closed circuit. When any one of the switch circuits is the first switch circuit,
When the switch of the first switch circuit is in a closed state, the first circuit is in a first mode, and when the switch is in an open state, the first circuit is in the second mode;
When any one of the switch circuits is the second switch circuit,
10. The antenna device according to claim 9 , wherein the second circuit is in the third mode when the switch of the second switch circuit is in a closed state, and in the fourth mode when the switch is in an open state. 2. The antenna device according to claim 1, wherein the power supply unit is also electrically connected to the first circuit and is capable of storing a current generated by an electromotive force of electromagnetic induction due to reception of electromagnetic waves of the predetermined frequency when the first circuit is in a first mode. 12. An antenna device according to claim 1,
one or more insulating substrates;
the first circuit and the second circuit formed on one surface of the substrate;
a spacer adjacent to the one surface of the substrate and having a through hole or a notch for protecting components of the first circuit and the second circuit;
A first base material disposed on an opposite side of the spacer from the substrate;
and a second substrate adjacent the other surface of the substrate. Further comprising an external contact terminal;
The dual interface card of claim 12 , wherein the first circuit is further capable of contact communication via the external contact terminals.