Control method, non-contact communication device, non-contact power supply device, program, and drive circuit
Abstract
Problem to be solved.To provide a control method, a non-contact communication device, a non-contact power feeding device, a program and a drive circuit which can deal with fluctuations in resonance frequency due to various factors and can obtain good communication characteristics.
Solution.This is a control method by a transmission / reception device 100 including an antenna having at least a resonance circuit including a variable capacitance capacitor VC1 at least in a part, and is communicated within a range in which the transmission / reception device 100 can communicate by LPP processing and discovery processing. Tuning is performed when the detection step for detecting the presence or absence of the device, the decision step for deciding whether or not to perform tuning based on the detection result in the detection step, and the decision step for deciding to perform tuning. Includes tuning steps to perform. [Selection diagram] Fig. 10

Term
Projected expiry 28 November 2034.
- Priority and filed
- Published
- Today
- Projected expiry
10 claims: 6 independent, 4 dependent
- 1少なくとも一部が可変容量コンデンサを含む共振回路を少なくとも有するアンテナを備える送受信装置による制御方法であって、 LPP処理およびディスカバリ処理により、前記送受信装置が通信可能な範囲内に通信機器が存在するか否かを検出する検出ステップと、 前記検出ステップにおける検出結果に基づき、チューニングを実行するか否かを決定する決定ステップと、 前記決定ステップにおいて前記チューニングを実行すると決定した場合に、前記チューニングを実行するチューニングステップとを含む制御方法。
- 2前記検出ステップで、前記LPP処理および前記ディスカバリ処理の双方において、前記通信機器が存在しないことを検出した場合、 前記決定ステップで、前記チューニングを実行することを決定する、請求項1に記載の制御方法。
- 3前記検出ステップで、前記LPP処理において前記通信機器が存在することを検出し、前記ディスカバリ処理において前記通信機器が存在しないことを検出した場合、 前記決定ステップで、前記チューニングを実行することを決定する、請求項1または請求項2に記載の制御方法。
- 4前記検出ステップで、前記LPP処理において前記通信機器が存在することを検出し、前記ディスカバリ処理において前記通信機器が存在しないことを検出した場合、 前記決定ステップで、前記チューニングを実行しないことを決定する、請求項1または請求項2に記載の制御方法。
- 5前記ディスカバリ処理は、前記通信機器からの信号を前記アンテナにより検出するカードモードと、所定の周波数の信号を前記アンテナから発信するR/Wモードとの少なくともいずれかを含む、請求項1乃至請求項4のいずれか一項に記載の制御方法。
- 6前記チューニングにおいて算出された前記アンテナを駆動する駆動回路への制御電圧である可変容量調整値と、当該チューニング前における前記駆動回路への制御電圧との差が、所定範囲以上である場合に、前記可変容量調整値を前記駆動回路への制御電圧として設定する設定ステップをさらに含む、請求項1乃至請求項3のいずれか一項に記載の制御方法。
- 7少なくとも一部が可変容量コンデンサを含む共振回路を少なくとも有するアンテナと、 LPP処理およびディスカバリ処理により、前記アンテナを使用して通信可能な範囲内に通信機器が存在するか否かを検出し、該検出結果に基づきチューニングを実行するか否かを決定し、前記チューニングを実行すると決定した場合に前記チューニングを実行する制御部とを備える非接触通信装置。
- 8少なくとも一部が可変容量コンデンサを含む共振回路を少なくとも有するアンテナと、 LPP処理およびディスカバリ処理により、前記アンテナを使用して通信可能な範囲内に通信機器が存在するか否かを検出し、該検出結果に基づきチューニングを実行するか否かを決定し、前記チューニングを実行すると決定した場合に前記チューニングを実行する制御部とを備える非接触給電装置。
- 9少なくとも一部が可変容量コンデンサを含む共振回路を少なくとも有するアンテナを備える非接触通信装置に、 LPP処理およびディスカバリ処理により、前記非接触通信装置が通信可能な範囲内に通信機器が存在するか否かを検出する検出ステップと、 前記検出ステップにおける検出結果に基づき、チューニングを実行するか否かを決定する決定ステップと、 前記決定ステップにおいて前記チューニングを実行すると決定した場合に、前記チューニングを実行するチューニングステップとを実行させるプログラム。
- 10制御部を備える非接触通信装置の駆動回路であって、 前記制御部が行うチューニングにおいて算出された制御電圧である可変容量調整値と、当該チューニング前における制御電圧との差が、所定範囲以上である場合に、前記可変容量調整値を、制御電圧として、少なくとも一部が可変容量コンデンサを含む共振回路を少なくとも有するアンテナに印加することにより、該アンテナを駆動する、駆動回路。
Independent claims10
162 paragraphs, as filed
The present invention relates to control methods, contactless communication devices, contactless power supply devices, programs and drive circuits.
In recent years, the spread of non-contact communication systems using NFC (Near Field Communication), which is a non-contact communication technology in a short distance, has been remarkable. In such a non-contact communication system, a transmission signal output from a transmission antenna (resonant circuit) of a system-dedicated reader / writer (hereinafter referred to as R / W) device is stored in a non-contact IC (Integrated circuit) card. The provided receiving antenna receives by electromagnetic induction action.
In such a non-contact communication system, in order to obtain good communication characteristics, the frequency of the signal source in the R / W device, the resonance frequency of the transmitting antenna of the R / W device, and the reception in the non-contact IC card It is important that the resonance frequencies of the antennas (resonant circuits) match each other. However, the resonance frequency of the receiving antenna of the non-contact IC card or the transmitting antenna of the R / W device varies due to various factors. In this case, it becomes difficult to stably transmit and receive information between the non-contact IC card and the R / W device.
Therefore, in the technical field of non-contact communication systems, various techniques for maintaining a good communication state under all conditions have been proposed. In Patent Document 1, as a transmitting device that performs non-contact communication with the outside by an electromagnetic induction action, a transmitting antenna, a signal output unit, a monitor circuit unit, and a correction circuit unit are provided, and the communication characteristics are described while monitoring the communication state. The technology for optimization is disclosed. In this transmitter, the monitor circuit unit monitors information about the current flowing through the antenna coil, determines the communication status based on the monitored information, and the correction circuit unit determines the communication status based on the determination result in the monitor circuit unit. Correct the communication characteristics (see, for example, paragraph [0137] of Patent Document 1).
<p num="0005"><patcit num="1"><text>Japanese Unexamined Patent Publication No. 2013-58170</text></patcit></p>
<p num="0006"> As described above, the resonance frequency of the antenna fluctuates due to various factors. For example, it fluctuates due to manufacturing variations in antenna characteristics, usage environment, changes over time, and the like. New measures against fluctuations in resonance frequency based on these factors are desired.</p><p num="0007"> An object of the present invention is to provide a control method, a non-contact communication device, a non-contact power feeding device, a program, and a drive circuit that can cope with fluctuations in the resonance frequency due to the above factors and can obtain good communication characteristics.</p>
<p num="0008"> In order to achieve the above object, the control method according to one embodiment of the present invention is It is a control method by a transmitter / receiver including an antenna having at least a resonance circuit including a variable capacitor at least in part. A detection step of detecting whether or not a communication device exists within a range in which the transmission / reception device can communicate by LPP processing and discovery processing, and a detection step. A decision step for deciding whether or not to perform tuning based on the detection result in the detection step, and When it is decided to execute the tuning in the determination step, the tuning step for executing the tuning is included.</p><p num="0009"> When it is detected in the detection step that the communication device does not exist in both the LPP process and the discovery process, In the determination step, it may be decided to perform the tuning.</p><p num="0010"> When the presence of the communication device is detected in the LPP process and the absence of the communication device is detected in the discovery process in the detection step, In the determination step, it may be decided to perform the tuning.</p><p num="0011"> When the presence of the communication device is detected in the LPP process and the absence of the communication device is detected in the discovery process in the detection step, In the determination step, it may be decided not to perform the tuning.</p><p num="0012"> The discovery process may include at least one of a card mode in which a signal from the communication device is detected by the antenna and an R / W mode in which a signal having a predetermined frequency is transmitted from the antenna.</p><p num="0013"> When the difference between the variable capacitance adjustment value, which is the control voltage to the drive circuit for driving the antenna, calculated in the tuning, and the control voltage to the drive circuit before the tuning is within a predetermined range, the above-mentioned It may further include a setting step of setting the variable capacitance adjustment value as a control voltage to the drive circuit.</p><p num="0014"> Further, the non-contact communication device according to one embodiment of the present invention is An antenna that has at least a resonant circuit, at least in part, including a variable capacitor. The LPP process and the discovery process detect whether or not a communication device exists within a communicable range using the antenna, determine whether or not to perform tuning based on the detection result, and perform the tuning. It includes a control unit that executes the tuning when it is determined to execute the tuning.</p><p num="0015"> Further, the non-contact power feeding device according to one embodiment of the present invention is An antenna that has at least a resonant circuit, at least in part, including a variable capacitor. The LPP process and the discovery process detect whether or not a communication device exists within a communicable range using the antenna, determine whether or not to perform tuning based on the detection result, and perform the tuning. It includes a control unit that executes the tuning when it is determined to execute the tuning.</p><p num="0016"> Further, the program according to one embodiment of the present invention is For non-contact communication devices having at least an antenna having a resonant circuit containing a variable capacitor at least in part. A detection step of detecting whether or not a communication device exists within a range in which the non-contact communication device can communicate by LPP processing and discovery processing, and a detection step. A decision step for deciding whether or not to perform tuning based on the detection result in the detection step, and When it is determined in the determination step that the tuning is to be executed, the tuning step for executing the tuning is executed.</p><p num="0017"> Further, the drive circuit according to one embodiment of the present invention is A drive circuit for a non-contact communication device equipped with a control unit. When the difference between the variable capacitance adjustment value, which is the control voltage calculated in the tuning performed by the control unit, and the control voltage before the tuning is within a predetermined range, the variable capacitance adjustment value is used as the control voltage. The antenna is driven by applying at least a part to an antenna having a resonance circuit including a variable capacitance capacitor.</p>
<p num="0018"> According to the present invention, it is possible to deal with fluctuations in the resonance frequency due to various factors, and it is possible to obtain good communication characteristics.</p>
<figref num="1">FIG. 1 is a functional block diagram showing a schematic configuration of a non-contact communication system according to the first embodiment of the present invention.</figref><figref num="2">FIG. 2 shows the circuit configuration of the non-contact communication device according to the first embodiment of the present invention.</figref><figref num="3">FIG. 3A shows a single-drive impedance matching circuit, FIG. 3B shows a differential-drive impedance matching circuit, FIG. 3C shows a modification of FIG. 3B, and FIG. 3D shows a modification of FIG. 3A. ..</figref><figref num="4">FIG. 4A is a graph showing the characteristics of the LSI current and its phase, and the antenna current flowing through the antenna and its phase, and FIG. 4B is a graph showing the characteristics of the impedance and its phase when the antenna is viewed from the antenna drive unit. ..</figref><figref num="5">FIG. 5 is an enlarged graph showing the deviation between the resonance point (frequency of phase 0) and the frequency at the minimum impedance.</figref><figref num="6">FIG. 6 is a graph showing the general relationship between the resonant frequency and the capacitance and impedance of the parallel resonant capacitor.</figref><figref num="7">FIG. 7 is a graph showing the relationship between the resonance frequency and the LSI current at different inductances of the antenna coil.</figref><figref num="8">FIG. 8 is a flowchart showing a process of automatically tuning the resonance frequency of the non-contact communication device at the time of factory shipment of the non-contact communication device.</figref><figref num="9">FIG. 9 is a diagram showing a timing chart of the processing shown in FIG.</figref><figref num="10">FIG. 10 is a flowchart of a process for determining a mode for determining whether or not the non-contact communication device automatically tunes the resonance frequency after the non-contact communication device is shipped from the factory.</figref><figref num="11">FIG. 11 is a diagram showing an example of timing charts in mode 1 and mode 3.</figref><figref num="12">FIG. 12 is a diagram showing an example of timing charts in mode 2 and mode 4.</figref><figref num="13">FIG. 13 is a flowchart showing a self-tuning process by the non-contact communication device after the non-contact communication device is shipped from the factory.</figref><figref num="14">FIG. 14 shows the circuit configuration of the non-contact communication device according to the second embodiment of the present invention.</figref><figref num="15">FIG. 15 shows the circuit configuration of the non-contact communication device according to the third embodiment of the present invention.</figref><figref num="16">FIG. 16 is a functional block diagram showing a schematic configuration of the contactless power supply system when the technology of the contactless communication system shown in FIG. 1 is applied to the contactless power supply system.</figref><figref num="17">FIG. 17 shows a sequence from detection (device detection) of a power receiving device in a power feeding device to charging (power transmission).</figref>
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment] (Non-contact communication system) FIG. 1 is a functional block diagram showing a schematic configuration of a non-contact communication system according to the first embodiment of the present invention. In FIG. 1, the wiring related to information input / output between each circuit block is indicated by a solid line arrow, and the wiring related to power supply is indicated by a broken line arrow.
The non-contact communication system 1 according to the present embodiment includes NFC (Near Field Communication), which is a short-range wireless communication technology including NFC-A, NFC-B, NFC-F, etc. based on the international standard ISO / IEC 18092. , Applicable to WPC (Wireless Power Consortium), which is a non-contact power supply technology. That is, the non-contact communication system 1 is applied to a communication / power supply system that performs non-contact communication and power supply by electromagnetic induction between the coils of the primary side antenna portion and the secondary side antenna portion.
The non-contact communication system 1 includes a transmitting device 100 (transmitting / receiving device 100) and a receiving device 200. The transmitting device 100 and the receiving device 200 can each function as a non-contact communication device. The non-contact communication system 1 transmits / receives information by non-contact communication between the transmitting device 100 and the receiving device 200. An example of the non-contact communication system 1 is a communication system that combines a non-contact IC card standard such as Felica (registered trademark) and an NFC standard.
(Transmitter) The transmission device 100 will be described. The transmitting device 100 is a device having a reader / writer (R / W) function for reading and writing data without contacting the receiving device 200. As shown in FIG. 1, the transmission device 100 includes an antenna resonance unit (antenna circuit) 110, a transmission / reception control unit 113, a transmission signal generation unit 114, a modulation circuit 116, a demodulation circuit 117, and a system control unit 118.
The antenna resonance portion 110 includes a primary side antenna portion 111 and an impedance matching portion 112, and constitutes a resonance circuit including an antenna coil and a resonance capacitor (a capacitor portion having a variable capacitance capacitor) as described later. The antenna resonance unit 110 transmits / receives a signal to / from the secondary side antenna unit 201 of the receiving device 200 by electromagnetic coupling.
The transmission / reception control unit 113 measures the output current of the voltage generation circuit (mainly the DAC (digital / analog converter) 133 described later) for adjusting the capacitance of the resonance capacitor and the antenna drive unit (antenna drive device) 130 described later. It has a measuring instrument (mainly a differential amplifier A3 and an ADC (analog / digital converter) 134, which will be described later). The primary side antenna unit 111 transmits a transmission signal of a desired frequency by the resonance circuit, and also receives a response signal from the receiving device 200, which will be described later.
The impedance matching unit 112 has a function as a matching circuit for matching the impedance between the transmission signal generation unit 114 and the primary antenna unit 111. Although not shown in FIG. 1, the impedance matching unit 112 includes a variable capacitor (hereinafter, also referred to as a variable capacitor). In the present embodiment, in the voltage generation circuit, by adjusting the capacitance of the variable capacitor as described later, impedance matching between the transmission signal generation unit 114 and the primary side antenna unit 111 and optimization of the resonance frequency are realized. To do.
As the variable capacitor, a small ceramic type capacitor is typically used. The ferroelectric material is BaSrTiO.<sub>3</sub>Etc. are used, and the capacitance is changed by changing the relative permittivity of this material. As the variable capacitor, a type using an RF switch or a MEMS (Micro Electro Mechanical Systems) type may be used.
The transmission signal generation unit 114 modulates a carrier signal of a desired frequency (for example, 13.56 MHz) with the transmission data input from the modulation circuit 116, and transmits the modulated carrier signal to the primary side antenna via the impedance matching unit 112. Output to unit 111.
The modulation circuit 116 encodes the transmission data input from the system control unit 118, and outputs the encoded transmission data to the transmission signal generation unit 114.
The demodulation circuit 117 acquires the response signal received by the primary antenna unit 111 via the impedance matching unit 112, and demodulates the response signal. Then, the demodulation circuit 117 outputs the demodulated response data to the system control unit 118.
The system control unit 118 generates control signals for various controls according to an external command or a built-in program, outputs the control signals to the modulation circuit 116 and the transmission / reception control unit 113, and outputs the control signals to the modulation circuit 116 and transmission / reception control. Controls the operation of unit 113. Further, the system control unit 118 generates transmission data corresponding to the control signal (command signal) and supplies the transmission data to the modulation circuit 116. Further, the system control unit 118 performs a predetermined process based on the response data demodulated by the demodulation circuit 117.
In the example shown in FIG. 1, it has been described that the transmission / reception control unit 113 and the system control unit 118 are separately provided in the transmission device 100, but the transmission device 100 is not limited to this example. For example, in the transmission device 100, the circuit may be configured so that the transmission / reception control unit 113 is included in the system control unit 118.
(Receiver) Next, the receiving device 200 will be described. Note that FIG. 1 shows an example in which the receiving device 200 is configured as a non-contact IC card (data carrier).
As shown in FIG. 1, the receiving device 200 includes a secondary antenna unit 201, a receiving control unit 202, a system control unit 203, a rectifying unit 204, a demodulation circuit 205, a modulation circuit 206, and a constant voltage, which have a function as a receiving antenna. A unit 207 and a battery 208 are provided.
The secondary side antenna unit 201 has, for example, a resonance circuit including a resonance coil (not shown) and a plurality of resonance capacitors. This resonant capacitor includes a variable capacitor whose capacitance changes by applying a control voltage. The secondary side antenna unit 201 communicates with the primary side antenna unit 111 of the transmission device 100 by electromagnetic coupling, receives the magnetic field generated by the primary side antenna unit 111, and receives the transmission signal from the transmission device 100. .. At this time, the capacitance of the variable capacitor is adjusted so that the resonance frequency of the secondary side antenna unit 201 becomes a desired frequency.
The rectifying unit 204 is composed of, for example, a half-wave rectifying circuit including a rectifying diode and a rectifying capacitor, rectifies the AC power received by the secondary side antenna unit 201 into DC power, and determines the rectified DC power. Output to voltage section 207.
The constant voltage unit 207 performs voltage fluctuation (data component) suppression processing and stabilization processing on the electric signal (DC power) input from the rectifying unit 204, and transfers the processed DC power to the reception control unit 202. Supply. The DC power output via the rectifying unit 204 and the constant voltage unit 207 is used as a power source for operating the IC in the receiving device 200.
The reception control unit 202 has a function of controlling the resonance characteristic of the secondary side antenna unit 201 to optimize the resonance frequency at the time of reception. Specifically, a control voltage is applied to the variable capacitor included in the secondary side antenna unit 201 to adjust its capacitance, thereby adjusting the resonance frequency of the secondary side antenna unit 201.
The demodulation circuit 205 demodulates the received signal received by the secondary side antenna unit 201, and outputs the demodulated signal to the system control unit 203.
Based on the signal demodulated by the demodulation circuit 205, the system control unit 203 determines the content thereof, performs necessary processing, and controls the modulation circuit 206 and the reception control unit 202.
The modulation circuit 206 modulates the receiving carrier according to the result (content of the demodulated signal) determined by the system control unit 203 to generate a response signal. Further, the modulation circuit 206 outputs the generated response signal to the secondary side antenna unit 201. The response signal output from the modulation circuit 206 is transmitted from the secondary side antenna unit 201 to the primary side antenna unit 111 by non-contact communication.
The battery 208 supplies power to the system control unit 203. Charging of the battery 208 is performed by connecting the charging terminal to the external power source 50. When the receiving device 200 has a configuration in which the battery 208 is built-in as shown in FIG. 1, more stable power can be supplied to the system control unit 203, and stable operation becomes possible.
The receiving device 200 may be configured to drive the system control unit 203 by using the DC power generated through the rectifying unit 204 and the constant voltage unit 207 without using the battery 208.
In the non-contact communication system 1 of the present embodiment, data communication is performed non-contact between the primary side antenna unit 111 of the transmitting device 100 and the secondary side antenna unit 201 of the receiving device 200 via electromagnetic coupling. Therefore, in order to efficiently communicate with the transmitting device 100 and the receiving device 200, the resonance circuits of the primary side antenna unit 111 and the secondary side antenna unit 201 resonate at the same carrier frequency (for example, 13.56 MHz). It is composed.
(Circuit configuration of non-contact communication device) FIG. 2 shows the circuit configuration of the transmission device 100, which is a non-contact communication device. The non-contact communication device includes an antenna resonance unit 110, a filter unit 120, an antenna drive unit 130, a control unit 140, and a storage unit 141.
The antenna resonance unit 110 has an antenna coil L3 and an impedance matching unit 112. The antenna resonance portion 110 is configured by connecting the impedance matching portion 112 to the antenna coil L3. The impedance matching unit 112 prevents impedance mismatch between the antenna drive unit 130 and the antenna coil L3, and keeps the load of the antenna drive unit 130 constant and pure resistance regardless of the antenna coil L3.
Specifically, the antenna resonance section 110 is configured as a series-parallel resonance circuit in which, for example, a variable capacitor (parallel resonance capacitor section) VC1 is connected in parallel and fixed capacitor capacitors C2 and C5 (series resonance capacitor section) are connected in series. Will be done. The capacitance of the variable capacitor VC1 changes as the input control voltage (control signal) changes, and as a result, the resonance frequency of the antenna resonance portion 110 changes. A plurality of variable capacitors may be provided, and the capacitances of the plurality of variable capacitors may be configured to change according to the same control voltage value.
The capacitors C7 and C8 have a DC cut function to prevent the control voltage (DC voltage) applied to the variable capacitor VC1 from leaking to the antenna L3. Capacitors C9 and C10 are additional capacitors for absorbing differences in antenna characteristics due to differences in antenna size and the like.
The impedance matching unit 112 has damping resistors R1 and R2 that determine the Q value (Quality Factor, sharpness) of the antenna resonance unit 110.
The filter unit 120 has coils L1 and L2 and capacitors C1 and C4, and has an EMC (Electro Magnetic Compatibility) function. The high-frequency oscillation signal (transmission signal described above) output from the antenna drive unit 130 is a rectangular wave. The filter unit 120 removes high-frequency noise due to this oscillation signal. The coils L1 and L2 are connected to one terminal of the capacitors C2 and C5, respectively. Capacitors C1 and C4 are connected between coils L1 and L2, respectively, and ground.
The antenna drive unit 130 includes an oscillation unit 131 that can control the oscillation frequency, an output unit 135 that supplies an oscillation signal obtained by the oscillation unit 131 to the antenna resonance unit 110, and a gain controller 132 that controls the output gain of the oscillation unit 131. And. Further, the antenna drive unit 130 includes a DAC 133 that converts a digital control voltage value from the control unit 140, which will be described later, into an analog signal, and a measurement unit that includes a differential amplifier A3 that measures the output current from the output unit 135. , Includes ADC134, which receives the output signal of the differential amplifier A3 and converts it into a digital signal. The antenna drive unit 130 is configured by, for example, an LSI (Large Scale Integration).
Further, the non-contact communication device includes a control unit 140 that controls the oscillation frequency of the oscillation unit 131 and the antenna resonance frequency of the antenna resonance unit 110, and a storage unit 141 that stores the antenna parameters and the set values such as the oscillation frequency by the oscillation unit 131. And. The control unit 140 corresponds to the transmission / reception control unit 113 and the system control unit 118 in FIG. 1, or a functional unit in which the two function as one.
The oscillation unit 131 is composed of a frequency variable oscillator whose oscillation frequency can be controlled over a wide range, for example, 12 to 17 MHz, by a frequency control signal supplied from the control unit 140. In particular, the oscillation unit 131 is configured to be able to output a signal of an oscillation frequency set offset from a predetermined frequency to the antenna resonance unit 110, as will be described later.
In the present embodiment, the predetermined frequency is a design value determined by the design of the inductance, Q value, impedance, etc. of the antenna resonance portion 110, and is a frequency at which the impedance phase becomes 0, as will be described later. These are the design values that determine the antenna characteristics. The frequency at which the impedance phase becomes 0 may match the standard value of 13.56 MHz, or may deviate without matching.
Further, in the present embodiment, the target frequency, which is the final oscillation frequency obtained by offsetting from a predetermined frequency, may be 13.56 MHz, which is a standard value, or may be different from the standard value depending on the manufacturer, in the vicinity of the standard value. It may be set to a value. The target frequency is, for example, the frequency at which the output current of the antenna drive unit 130 (hereinafter, also referred to as LSI current) is minimized.
Therefore, the predetermined frequency and the target frequency are eigenvalues that differ depending on the manufacturer or product model.
The output unit 135 includes a pair of differential amplifiers A1 and A2 that output a high-frequency oscillation signal supplied from the oscillation unit 131 as a positive-phase oscillation signal and a negative-phase oscillation signal.
The measuring unit is connected to the input end and the output end of the differential amplifier A1 of the output unit 135. The measuring unit measures the output current (hereinafter referred to as LSI current) I_lsi of the differential amplifier A1. The LSI current is measured by converting the voltage difference between the voltage V1 of the oscillation signal input to the differential amplifier A1 and the voltage V2 of the positive phase oscillation signal output from the differential amplifier A1 by the output resistance. The measuring unit supplies the measurement result to the control unit 140 via the ADC 134.
The control unit 140 has a function of controlling the R / W function and the card function of the non-contact communication device. The R / W function is a function in which a non-contact communication device communicates (reads / writes data) with a receiving device 200, which is a secondary device (counterpart device), as a transmitting device shown in FIG. The card function is a function of the receiving device 200, which is the secondary device shown in FIG. 1, and means that the non-contact communication device has that function.
The control unit 140 controls the control voltage applied to the variable capacitor VC1 so that the resonance frequency of the antenna resonance unit 110 becomes a set predetermined frequency. The DAC 133 converts the digital control voltage value output from the control unit 140 into an analog control voltage signal Vcnt, and applies it to the variable capacitor VC1 via the control signal line 119 of the antenna resonance unit 110. This makes it possible to change the impedance of the antenna resonance portion 110 at high speed in 1 ms or less. The control unit 140 is composed of, for example, a CPU (Central Processing Unit) or the like.
In the antenna drive unit 130, the control value input unit 139 is a terminal or line to which the control voltage value from the control unit 140 is input.
As a basic matching circuit used in non-contact communication such as an NFC system, there are circuit configurations of the types shown in FIGS. 3A to 3D, respectively. The type shown in FIG. 3A is a single drive type that drives the antenna coil L3 in one channel, and the type shown in FIG. 3B is a differential drive type that drives the antenna coil L3 in two channels. The basic operation is the same in the circuit configurations shown in both FIGS. 3A and 3B. The Tx1 terminal and the Tx2 terminal are the drive terminals of the antenna drive unit 130. The matching circuit shown in FIG. 3C is a modification of FIG. 3B and is used in non-contact communication as in FIG. 3B. The matching circuit shown in FIG. 3D has a configuration of a series resonant circuit in a modified example of FIG. 3A, and is used for, for example, non-contact feeding.
The antenna resonance portion 110 in the non-contact communication device has a differential drive type circuit configuration in which the antenna coil L3 is driven by two channels.
In FIG. 2, the lines connected to the Tx1 terminal and Tx2 in the antenna resonance unit 110 are the input lines 129 to which the oscillation signal from the oscillation unit 131 is input. In the case of 2 channels, there are 2 input lines 129, and in the case of 1 channel, there is 1 input line 129.
In the R / W mode, the control unit 140 oscillates the oscillation unit 131 at an arbitrary frequency within the above frequency range, and the positive phase oscillation signal and the negative phase oscillation signal having that frequency are output from the output unit 135 to the Tx1 terminal. And control so that it is output to the Tx2 terminal.
In the card mode, the control unit 140 detects the reception signal induced in the antenna coil L3 of the antenna resonance unit 110 by a reception circuit (not shown), and controls the response by load modulation.
FIG. 4A is a graph showing the characteristics of the LSI current and its phase, and the antenna current flowing through the antenna coil L3 and its phase. FIG. 4B is a graph showing the impedance (impedance when the antenna is viewed from the antenna drive unit 130) and its phase characteristics. The solid line is the impedance (Ω) and the broken line is the phase (deg). The horizontal axis is frequency. The left vertical axis of FIG. 4A shows the current value, the right vertical axis shows the phase, the left vertical axis of FIG. 4B shows the impedance, and the lower right vertical axis shows the phase.
As shown in the graph of FIG. 4B, in the series-parallel resonance circuit as in this embodiment, there are two resonance points where the impedance phase becomes 0 (the first phase 0 point and the second phase in FIG. 4). 0 points). The resonance point with the lower frequency (that is, the first phase 0 point) is the point where the impedance phase changes from minus to plus, and the series resonance mainly by the series resonance capacitors C2 and C5 and the antenna coil L3. It is a point. At the first phase 0 point, there is a frequency at which the impedance is minimized due to series resonance. Due to the influence of the variable capacitor VC1 which is a parallel resonance capacitor in the series-parallel resonance circuit, the impedance becomes the minimum at the frequency lower than the frequency of phase 0.
The resonance point having a higher frequency (that is, the second phase 0 point) is a point where the impedance phase changes from plus to minus, and is mainly a parallel resonance point between the variable capacitor VC1 and the antenna coil L3. At the second phase 0 point, there is a frequency at which the impedance is maximized due to parallel resonance. Due to the influence of the series resonance capacitors C2 and C5 of the series-parallel resonance circuit, the impedance becomes maximum at a frequency higher than the frequency of phase 0.
Here, there are two general tuning designs, one is to match the series resonance point to the system frequency (for example, 13.56MHz), and the other is to match the parallel resonance point to the system frequency. Be selected.
The amount of deviation between the resonance point (frequency of phase 0) and the frequency at the minimum or maximum impedance varies depending on the design values such as the inductance, Q value, and impedance of the antenna coil. FIG. 5 is an enlarged graph showing this deviation. This graph shows the results of calculating the impedance of the antenna and each current of the antenna resonance unit 110 by changing the oscillation frequency of the oscillation unit 131 while fixing each resonance capacitor in series and parallel. Here, an antenna with L = 1.25uH is used, the series resonance point is adjusted to, for example, 13.56MHz, and the impedance Z = 8Ω (low impedance type) is designed (in contrast, in Fig. 4, the parallel resonance point is set. An example is shown for 13.56MHz). Each current shown in FIG. 5 is an antenna current, an LSI current, and a filter current (current flowing through the filter unit 120).
As shown in Fig. 5, the antenna current peaks at 13.56MHz as designed, but the frequency at which the impedance is minimized and the frequency at which the LSI current is maximized deviates from 13.56MHz to 13.46Hz, which is a low frequency of about 100KHz. You can see that there is.
In this way, a deviation between the resonance point (frequency of phase 0) (see FIG. 4) and the frequency at the minimum or maximum impedance occurs. Therefore, in order to correct this deviation, the offset value (corresponding to the above). The target frequency is set based on the amount of deviation). The offset value is determined by calculating and actually measuring for each product model, for example.
Here, a low-impedance type antenna device whose series resonance point is adjusted to 13.56 MHz is easily affected by the output resistance of the LSI, and is generally used in combination with an LSI having an output resistance of 1 Ω or less. Since a series resonance point is used, the impedance change is small and stable in the vicinity of the resonance point with respect to the resonance frequency shift.
On the other hand, a high-impedance type antenna device that adjusts the parallel resonance point to 13.56 MHz (for example, see the graph shown in Fig. 4) is not easily affected by the large output resistance of the LSI, and the output resistance is high. It is generally used in combination with an LSI of several Ω. There is an advantage that the LSI current can be reduced by increasing the impedance by using the parallel resonance point.
The example shown in FIG. 4 shows the characteristics of a high impedance type (for example, 80Ω) antenna device of the type that adjusts the parallel resonance point to 13.56MHz as described above. Here, in the present embodiment, an example in which the matching constant of the high impedance type antenna device is designed will be mainly described.
FIG. 6 is a graph showing the general relationship between the resonance frequency and the capacitance and impedance of the parallel resonant capacitor section. This graph shows general relationships (characteristics) and is not limited to the numerical values shown in the graph. The inductance of the antenna coil in FIG. 6 is 1.25 μH. The relationship between the resonance frequency and the capacitance can be approximated by a straight line. Impedance peaks near 13.56MHz. It can be seen that the resonance frequency and impedance can be changed by changing the capacitance of the parallel resonance capacitor.
FIG. 7 is a graph showing the relationship between the resonance frequency and the LSI current at different inductances (L = 0.75 μH, 1.0 μH, 1.25 μH, 1.5 μH) of the antenna coil. The minimum value of LSI current is the same regardless of the inductance of the antenna coil. From this, it can be seen that the resonance frequency is the frequency at which the LSI current is the minimum, regardless of the inductance. That is, the inventor of the present disclosure uses an oscillation frequency offset from a predetermined frequency as the target frequency to change the capacitance of the parallel resonance capacitor of the series-parallel resonance circuit and uses the parallel resonance point to obtain the resonance frequency. When tuning, it was found that the LSI current should be measured while changing the capacitance of the parallel resonant capacitor to detect the minimum value. In the present embodiment, the resonance frequency is tuned by detecting the minimum value of the LSI current in this way. However, when the resonance frequency is tuned using the series resonance point, the opposite is true. , The maximum value of the LSI current may be detected while changing the capacitance of the parallel resonant capacitor.
As shown in FIG. 4, the resonance frequency at which the phase is actually 0 and the frequency at which the impedance is the maximum (the LSI current is the minimum) deviate from each other. Therefore, as described above, the designer deviates from the predetermined frequency and the predetermined frequency based on the design value (inductance, Q value, impedance, etc.) of the antenna resonance portion 110 and the frequency at which the LSI current is minimized. Estimate the amount (offset value) in advance, and store those values in, for example, the storage unit 141 (see FIG. 2). In this case, the target frequency, which is the frequency obtained by offsetting, may be stored, and both the predetermined frequency and the offset value may be stored.
In order to obtain this target frequency, the control unit 140 outputs an optimum control value which is a control voltage signal to the variable capacitor VC1 for obtaining the minimum value of the LSI current. In this case, for example, as shown in FIG. 4, when the parallel resonance point deviates from a predetermined frequency (typically 13.56 MHz) downward, it is offset from the parallel resonance point as a tuning frequency, that is, a target frequency. Set it higher by the value.
The same applies to the case where the parallel resonance capacitor of the series-parallel resonance circuit, that is, the variable capacitor VC1 is changed and the resonance frequency is tuned using the series resonance point. In this case, the resonance frequency at which the phase is actually 0 and the frequency at which the impedance is minimized deviate as shown in FIG. Since the series resonance point deviates higher from a predetermined frequency (typically 13.56 MHz), the target frequency may be set lower by the offset value from the series resonance point.
As described above, depending on the manufacturer, a frequency deviated from 13.56 MHz, which is empirically obtained so as to have the best communication characteristics, may be set as the target frequency.
The non-contact communication device according to the present embodiment is tuned using the LSI current instead of the antenna current shown in Patent Document 1, and as will be described later, the LSI is equipped with a tuning function at low cost. be able to. However, as shown in Fig. 5, the resonance frequency at which the impedance phase (see Fig. 4) becomes 0 and the maximum value of the antenna current match well, but the minimum or maximum value of the LSI current deviates, so this is an error. It is a factor. Therefore, by correcting this deviation as an offset, accurate tuning can be performed.
As described above, in addition to storing the offset value as a frequency, for example, from the characteristics of the capacitance vs. resonance frequency shown in FIG. 6, the frequency offset is converted into a capacitance offset and stored as a voltage value corresponding to the capacitance offset. It is also possible. In this case, in the manufacturing stage, tuning of the resonance frequency is performed at a predetermined frequency without offset, and a voltage corresponding to the above offset is applied to the obtained voltage value, whereby an effect equivalent to the frequency offset can be obtained. .. In this case, no frequency offset is required, so if the predetermined frequency is the system frequency of 13.56MHz, the oscillator 131 can set the oscillation frequency to the fixed frequency of 13.56MHz, which has the advantage of simplifying the LSI circuit. is there.
(Processing of non-contact communication device) <Factory default> FIG. 8 is a flowchart showing a process of automatically tuning the resonance frequency of the non-contact communication device at the time of shipment from the factory.
As initialization, the control unit 140 reads the target frequency f0 offset from the predetermined frequency from the storage unit 141, and sets this in the oscillation unit 131 (step 101).
As initialization, the control unit 140 sets the antenna parameters stored in the storage unit 141 in advance in the internal registers of the control unit 140, the gain controller 132, and the like (step 102). The antenna parameters are, for example, impedance, Q value, gain of oscillation signal output from oscillation unit 131, control voltage value of DAC133 to variable capacitor VC1 (here, for example, 0V as an initial value) and the like.
The control unit 140 increases the control voltage value to the DAC 133 from 0V, for example, by a unit voltage in each step, and measures the LSI current by the measurement unit in each step (step 103). For example, the control unit 140 increases the control voltage value up to 3V, which is the maximum value of the system voltage. When the control unit 140 detects the minimum value of the LSI current between 0 and 3V (Yes in step 104), the control unit 140 performs the optimum control which is the control voltage value to the DAC 133 when the LSI current is the minimum. The value is stored in the storage unit 141 (step 105).
It is not necessary to increase the control voltage value of the control unit 140 to 3V, and if the control unit 140 detects the minimum value while the control voltage value is increasing from 0V, the process may proceed to step 105 at that point. ..
After that, the control unit 140 sets the oscillation frequency for communication (for example, 13.56 MHz) to the oscillator 131 (step 106). The control unit 140 sets the antenna parameters for communication (step 107), and ends the tuning process. As one of the antenna parameters for communication, there is an optimum control value stored in the storage unit 141. That is, at the time of communication, the control unit 140 controls the resonance frequency using the optimum control value stored in the storage unit 141.
As will be described below, there are parameters for communication that are different from those for tuning. One of the parameters is, for example, the gain of the oscillation signal by the oscillation unit 131.
FIG. 9 shows a timing chart of the processing shown in FIG. The horizontal direction shows the passage of time, and the vertical direction shows the LSI current value schematically. After setting the antenna parameters for tuning, the control unit 140 detects the change in the LSI current and detects the minimum value by increasing the control voltage value to the DAC 133 by the unit voltage for each step. After that, the antenna parameters for communication are set and communication is performed.
The minimum (or maximum) detection period of the LSI current is preferably 50 to 100 μs. This is a sufficiently small value compared to the discovery time of 300 ms, which will be described later.
Here, as shown in FIG. 9, the magnitude of the LSI current, that is, the gain of the oscillation signal from the output unit 135, is a value during the detection period (second value) rather than a value during communication (first value). The gain is set so that the value of) is larger. As a result, the SN ratio of the current signal can be increased at the time of detection, so that the control unit 140 can obtain an accurate optimum control value. For example, the second value is preferably 1.5 to 2 times the first value, but is set within the allowable current range of the LSI.
<After factory shipment> FIG. 10 shows whether or not the non-contact communication device automatically tunes the resonance frequency (self-tuning process) after the non-contact communication device is shipped from the factory, for example, when the user uses the non-contact communication device. It is a flowchart of the process (mode determination process) for determining a mode for determining whether or not. In the self-tuning process by the non-contact communication device of the present embodiment, the non-contact communication device (or an electronic device equipped with the non-contact communication device) satisfies a predetermined condition based on the LPP (low power polling) process and the discovery process. Will be executed if
LPP processing is, for example, whether or not there is a transmitter / receiver having a card function within the communicable range of the non-contact communication device by intermittently transmitting a carrier signal for a short time of 50 to 300 μsec and performing polling. This is a process for performing simple detection of polling. In LPP processing, carrier signals are transmitted intermittently in a short period of time, so power consumption can be significantly reduced compared to normal polling. In the present embodiment, the transmission / reception device having a card function will be described below assuming that it is an IC card, but the transmission / reception device having a card function is not limited to this.
The discovery process is, for example, when a non-contact communication device has both an R / W function and a card function, a device having an R / W function (R / W mode) and a device having a card function (card mode). It is a process to detect the secondary side device by alternating with and. In the discovery process, the non-contact communication device operates in R / W mode, card mode, or both. In the present embodiment, the non-contact communication device will be described below assuming that the non-contact communication device performs the discovery process by performing both the operation modes of the R / W mode and the card mode.
In LPP processing, carrier signals are intermittently sent to perform polling, so even if the non-contact communication device detects the presence of an IC card by LPP processing, the detection may not always be highly accurate. That is, even if the non-contact communication device detects the existence of the IC card by the LPP process, the detection is an erroneous detection, and the IC card may not actually exist. On the contrary, when the detection sensitivity by LPP processing is low, even if the detected communication device detects that the IC card does not exist by LPP processing, the detection is erroneous and the IC card is actually detected. May exist.
False positives in LPP processing also occur due to changes in antenna characteristics due to changes in conditions after shipment from the factory. For example, if the temperature around the non-contact communication device before factory shipment and the temperature at the position where the non-contact communication device is installed after factory shipment change, the characteristics of the antenna may change. Further, for example, even if the non-contact communication device is placed in the same place after shipment from the factory, the characteristics of the antenna may change due to a change in ambient temperature due to a seasonal change or the like. Further, for example, when metal is present around the non-contact communication device, the antenna characteristics may change depending on the position of the metal with respect to the non-contact communication device, the distance between the non-contact communication device and the metal, and the like. In addition to these examples, when the antenna characteristics change due to changes in arbitrary conditions, it may be detected in the LPP processing that an IC card exists even if it does not exist in the vicinity of the non-contact communication device. ..
In contrast to the LPP process, in the discovery process, polling is performed to detect the presence or absence of an IC card by continuously transmitting a carrier signal in the R / W mode. Therefore, in the discovery process, whether or not an IC card exists around the non-contact communication device can be detected with higher accuracy than in the LPP process.
The non-contact communication device of the present embodiment detects the presence or absence of an IC card by performing LPP processing and discovery processing, and whether or not to automatically perform self-tuning of the resonance frequency according to the detected result. Determine the mode for determining. The modes are classified according to whether or not the presence of an IC card is detected in the LPP processing and the discovery processing, respectively. In the present embodiment, the non-contact communication device determines one of four modes from mode 1 to mode 4.
When the non-contact communication device detects the presence of the IC card in both the LPP process and the discovery process, it determines that the mode is 1. In mode 1, an IC card exists around the non-contact communication device, and the non-contact communication device is in a state of being able to communicate with the IC card. When the non-contact communication device determines the mode 1, the non-contact communication device does not perform the self-tuning process and starts communication with the IC card.
If the non-contact communication device detects the presence of the IC card in the LPP process but does not detect the presence of the IC card in the discovery process, it determines that the mode is 2. In mode 2, the presence of the IC card is detected by LPP processing. However, since the existence of the IC card is not detected by the discovery process, the IC card does not actually exist in the vicinity of the non-contact communication device. Therefore, the detection by LPP processing is an erroneous detection. That is, mode 2 indicates that the antenna identification changes due to changes in conditions. In this case, since the erroneous detection occurs due to the change in the conditions, the non-contact communication device does not have to perform the self-tuning process. Further, the non-contact communication device may perform a self-tuning process according to a change in conditions. Further, whether or not the non-contact communication device performs self-tuning may be determined in advance by, for example, a user input operation or the like. In the present embodiment, in the case of mode 2, the non-contact communication device will be described as performing self-tuning processing.
The non-contact communication device does not detect the presence of the IC card in the LPP process, but if it detects the presence of the IC card in the discovery process, it determines that the mode is 3. In mode 3, since the existence of the IC card is detected by the discovery process, the detection by the LPP process is a false detection due to the lack of accuracy, and the IC card actually exists around the non-contact communication device. .. Therefore, in mode 3, the non-contact communication device is in a state where it can communicate with the IC card. Therefore, when the non-contact communication device determines the mode 3, the non-contact communication device does not perform the self-tuning process and starts communication with the IC card.
The non-contact communication device determines that the mode is 4 when the presence of the IC card is not detected in both the LPP process and the discovery process. In mode 4, there is no IC card around the non-contact communication device, and the non-contact communication device performs self-tuning processing.
Table 1 shows the relationship between the detection results of the LPP processing and the discovery processing and the modes determined by the non-contact communication device. The non-contact communication device determines the mode based on the results of the LPP processing and the discovery processing as described in the above description and Table 1. Then, the non-contact communication device performs communication with the IC card or self-tuning process based on the determined mode.
<tables num="1"><img id="000003" he="31" wi="170" file="JP2016103233A_D0001.tif" img-format="tif" img-content="drawing" /></tables>
The mode determination process performed by the non-contact communication device will be specifically described with reference to FIG. First, the control unit 140 initializes the IC card detection (step 201). Then, the control unit 140 determines whether or not the IC card, which is the secondary device, exists within the communicable range by intermittently transmitting the carrier signal by the LPP process (step 202).
When the control unit 140 determines by the LPP process that the IC card exists within the communicable range (Yes in step 202), the control unit 140 then performs the discovery process.
Specifically, the control unit 140 sets the non-contact communication device to the R / W mode of the initial mode (step 203). Then, the control unit 140 monitors whether or not an IC card exists in the vicinity as a secondary device (step 204). In step 202, the non-contact communication device outputs an oscillation signal at predetermined time intervals to detect the presence or absence of the oscillation signal.
When the control unit 140 determines that the IC card exists (Yes in step 204), it determines that it is in mode 1 (step 208). Then, this flow ends, and the non-contact communication device starts communication with the detected IC card.
On the other hand, when the control unit 140 determines that the IC card does not exist (N in step 204), the control unit 140 switches the operation mode from the R / W mode to the card mode (step 205). Then, the control unit 140 monitors whether or not the R / W exists as the other party device (step 206).
When the control unit 140 determines that the R / W exists (Yes in step 206), the control unit 140 determines that the mode is 1 (step 208). Then, this flow ends, and the non-contact communication device starts communication with the detected R / W.
When the control unit 140 determines that the R / W does not exist (No in step S206), the control unit 140 determines whether or not a timeout has occurred (step 207). The control unit 140 starts counting up the timer at the timing of switching to the card mode in step 205, for example.
If the control unit 140 determines that the time-out has not occurred (No in step 207), the control unit 140 returns to step 203 and repeats the processes of steps 203 to 207 until the time-out occurs.
When the control unit 140 determines that the time-out has occurred (Yes in step 207), for example, in order to reduce the power consumption by the non-contact communication device, the control unit 140 stops the discovery, shifts to a low consumption mode such as standby, and in mode 2. Determine to be (step 209). Then, this flow ends, and the control unit 140 executes the self-tuning process after shipment from the factory.
On the other hand, when the control unit 140 determines by the LPP process that the IC card does not exist within the communicable range (No in step 202), the control unit 140 determines whether or not a timeout has occurred (step S210). The control unit 140 starts counting up the timer, for example, when the process first shifts to step 202.
When the control unit 140 determines that the time-out has not occurred (No in step 210), the control unit 140 returns to step 202 and repeats the detection of whether or not the IC card exists by the LPP process until the time-out occurs.
When the control unit 140 times out without detecting that the IC card is within the communicable range in the LPP process (Yes in step 210), the control unit 140 then performs the discovery process in steps 211 to 215.
Here, steps 211 to 215 correspond to steps 203 to 207, respectively, and the specific discovery process is the same as that of steps 203 to 207. Therefore, detailed description thereof will be omitted.
When the control unit 140 determines that the IC card exists in step 212 (Yes in step 212), the control unit 140 determines that the mode is 3 (step 216). Then, this flow ends, and the non-contact communication device starts communication with the detected IC card.
If the control unit 140 determines that the R / W exists in step 214 (Yes in step 214), the control unit 140 determines that the mode is 3 (step 216). Then, this flow ends, and the non-contact communication device starts communication with the detected R / W.
On the other hand, when the control unit 140 determines that the discovery process has timed out (No in step 215), for example, in order to reduce the power consumption by the non-contact communication device, the control unit 140 stops the discovery and shifts to a low consumption mode such as standby. At the same time, it is determined that the mode is 4 (step 217). Then, this flow ends, and the control unit 140 executes the self-tuning process after shipment from the factory.
In the description of FIG. 10, the non-contact communication device has been described as performing both the LPP process and the discovery process, but it is not necessary to execute either process depending on the nature or setting of the device. For example, if the non-contact communication device has only a card function, it may not use the LPP processing or may be set not to have the LPP processing function. In this case, the non-contact communication device may determine whether or not to execute self-tuning by executing the discovery process without executing the LPP process.
FIG. 11 is a diagram showing an example of timing charts in mode 1 and mode 3. In the timing chart of FIG. 11, the time elapsed in the horizontal direction and the LSI current value in the vertical direction are schematically shown. The non-contact communication device performs the discovery process after executing the LPP process. In the present embodiment, as the discovery process, polling is first executed in the R / W mode, and then it is detected in the card mode whether or not the R / W exists in the vicinity. When the non-contact communication device determines that it is in mode 1 or mode 3 as a result of the LPP process and the discovery process, it communicates with the peripheral communication device whose existence has been confirmed.
FIG. 12 is a diagram showing an example of timing charts in mode 2 and mode 4. In the timing chart of FIG. 12, the time elapsed in the horizontal direction and the LSI current value in the vertical direction are schematically shown. The non-contact communication device performs the discovery process after executing the LPP process. In the present embodiment, as the discovery process, polling is first executed in the R / W mode, and then it is detected in the card mode whether or not the R / W exists in the vicinity. The non-contact communication device performs self-tuning when it determines that it is in mode 2 or mode 4 as a result of LPP processing and discovery processing.
Next, in the present embodiment, the self-tuning process performed by the non-contact communication device in mode 2 or mode 4 will be described. FIG. 13 is a flowchart showing a self-tuning process by the non-contact communication device after the non-contact communication device is shipped from the factory.
As initialization, the control unit 140 reads a predetermined frequency f1 from the storage unit 141 and sets this in the oscillation unit 131 (step 301). The predetermined frequency f1 can be, for example, 13.56 MHz.
As initialization, the control unit 140 sets the antenna parameters stored in the storage unit 141 in advance in the internal registers of the control unit 140, the gain controller 132, and the like (step 302).
The control unit 140 increases the control voltage value to the DAC 133 from 0V, for example, by a unit voltage in each step, and measures the LSI current by the measurement unit in each step (step 303).
The control unit 140 determines whether or not the measured LSI current is the minimum value (step 304).
When the control unit 140 determines that the measured LSI current is not the minimum value (No in step 304), the control unit 140 determines whether or not the control voltage to the swept DAC 133 is 3V (step 311).
When the control unit 140 determines that the control voltage to the swept DAC 133 is not 3V (No in step 311), the control unit 140 proceeds to step 303.
On the other hand, when the control unit 140 determines that the control voltage to the swept DAC 133 is 3V (Yes in step 311), it executes error processing (step 312). Error processing is performed, for example, by notifying the user of an error signal from a non-contact communication device. Then, this flow ends.
When the control unit 140 determines that the LSI current is the minimum in step 304 (Yes in step 304), the control unit 140 determines the control voltage value to the DAC 133 when the LSI current is the minimum as the optimum control value (step 305).
It is not necessary to increase the control voltage value of the control unit 140 to 3V, and if the control unit 140 detects a minimum value while the control voltage value is increasing from 0V, it is regarded as the minimum value and at that time. You may proceed to step 305 with.
Next, the control unit 140 determines whether or not the difference between the control voltage (variable capacitance adjustment value) set in the oscillation unit 131 and the voltage stored in the storage unit 141 in step 305 is within a predetermined range or more. Determine (step 306). The predetermined range can be set as appropriate. For example, when the DAC 133 is a 5-bit DAC, 1 bit corresponds to a voltage of about 90 mV, and a predetermined range may be set to 2 bits.
When the control unit 140 determines that the difference between the variable capacitance adjustment value stored in advance and the optimum control value is smaller than the predetermined range (No in step 306), the step 307 and step 308 are not performed, and the step is performed. Proceed to 309.
On the other hand, when the control unit 140 determines that the difference between the variable capacitance adjustment value stored in advance and the optimum control value is within a predetermined range (Yes in step 306), the optimum control value is stored in the storage unit 141. Remember in (step 307). Then, the control unit 140 updates the control voltage of the oscillation unit 131 by setting the voltage stored in the storage unit 141 in the oscillation unit 131 (step 308).
After that, the control unit 140 sets the oscillation frequency for communication (for example, 13.56 MHz) to the oscillator 131 (step 309). The control unit 140 sets the antenna parameters for communication (step 310), and ends the self-tuning process. As one of the antenna parameters for communication, there is an optimum control value stored in the storage unit 141. That is, at the time of communication, the control unit 140 controls the resonance frequency using the optimum control value stored in the storage unit 141.
The self-tuning process performed by the non-contact communication device is not limited to the flow shown in FIG. For example, in the flow shown in FIG. 13, in steps 301 to 305, the minimum value of the LSI current is detected and the control voltage to the DAC 133 in that case is stored. However, instead of the self-tuning process, the self-tuning process may be executed so as to detect the optimum control value by detecting another value. As the above other values, for example, the following plurality of examples 1) to 4) may be detected. 1) Control voltage value at which the phase of the antenna current, which is the current flowing through the antenna coil, becomes 0, 2) Control voltage value at which the antenna current is the minimum or maximum, 3) Control voltage value at which the phase of the antenna impedance becomes 0, 4) Control voltage value at which the phase of the LSI current is 0
The point where each of the phases 1), 3), and 4) becomes 0 corresponds to the point where the phase of the curve shown by the broken line in FIG. 4 is 0 °. Fig. 4 shows the simulation results. Regarding the antenna current phase of 1) above, the point of -270 ° corresponds to the original phase of 0 °, and the LSI current phase of 4) above is -180. It should be noted that the point of ° corresponds to the original phase of 0 °.
Since the tuning period is about 50 to 100 μs as described above, the power consumption can be almost ignored, and the user is not aware of the tuning process.
Further, in the flow shown in FIG. 13, the control unit 140 may store the updated control voltage in the storage unit 141 each time the control voltage to the DAC 133 is updated in step 308. The user can browse the history of the control voltage stored in the storage unit 141 by a predetermined operation, and can use it as a reference at the time of maintenance, for example.
In this example, the case where the non-contact communication device has both the R / W function and the card function has been described, but the same processing is performed in the non-contact communication device having only the R / W function or only the card function. It can be performed. For example, when a non-contact communication device has only an R / W function, it does not shift to communication even if the presence of R / W is detected in the vicinity of the non-contact communication device as the R / W function. Further, when the non-contact communication device has only a card function, the communication does not shift even if the presence of an IC card is detected in the vicinity of the non-contact communication device as the card function.
As another example, when the non-contact communication device has only the R / W function, it monitors whether or not there is an IC card in the vicinity as the R / W function, and if its existence is not detected, it may time out. .. When the non-contact communication device has only a card function, it monitors whether R / W exists in the vicinity as a card function, and if its existence is not detected, it may time out. As described above, the non-contact communication device has an advantage that the time for detecting the presence of peripheral communication devices is shortened by performing a time-out based on the function.
(Summary) As described above, in the non-contact communication device according to the present embodiment, the measuring unit measures the output current from the oscillating unit 131, and the control unit 140 detects the minimum value of the output current and sets the minimum value. The resonance frequency is controlled using the corresponding optimum control value. Therefore, even if the resonance frequency may fluctuate due to manufacturing variations in antenna characteristics, or due to changes in the usage environment or aging, good communication characteristics due to the set resonance frequency can be obtained.
In the non-contact communication device according to the present embodiment, the differential amplifier A3, which is an LSI current measuring unit, is provided in the antenna driving unit 130. Therefore, unlike Patent Document 1, it is not necessary to provide a resistor or wiring for monitoring the antenna current in the antenna resonance portion 110 between the antenna resonance portion 110 and the antenna drive portion 130. Further, for that purpose, the number of terminals of the antenna drive unit 130 is not increased, so that a simple circuit configuration can be obtained. As a result, the design of the antenna drive unit 130 can be facilitated and the cost can be reduced. Further, this makes it difficult for noise to occur, and good communication characteristics can be obtained.
Since the non-contact communication device according to the present embodiment has a configuration that can be automatically tuned at the time of shipment from the factory, manual tuning by an operator on the production line is not required. As a result, cost reduction can be realized.
The optimum control value at the time of shipment from the factory may differ from the optimum control value at the time of using the user's non-contact communication device depending on the usage environment of the non-contact communication device and the time-dependent change of the antenna resonance portion 110. The non-contact communication device according to the present embodiment can maintain good communication characteristics because it can be automatically self-tuned even when the user uses it after factory shipment.
Moreover, since the non-contact communication device according to the present embodiment determines whether or not the self-tuning process needs to be executed by performing the LPP process and the discovery process, it is an external device in response to changes in conditions after shipment from the factory. The self-tuning process can be executed without causing an adjustment deviation due to. Further, since the self-tuning process for such a change in the condition may not be executed by the user's selection, self-tuning according to the usage mode of the user is possible.
Further, the non-contact communication device according to the present embodiment updates the control voltage to the DAC 133 when the difference between the variable capacitance adjustment value and the calculated voltage stored in the storage unit 141 is within a predetermined range. If the difference is smaller than the predetermined range and the control voltage does not need to be updated, the update process is not performed. In this way, the non-contact communication device according to the present embodiment can reduce the number of update processes.
[Second Embodiment] Next, a second embodiment of the present invention will be described. In the following description, substantially the same elements will be assigned the same reference numerals to the members and functions included in the apparatus according to the first embodiment, and the description thereof will be simplified or omitted, focusing on the differences. explain.
FIG. 14 shows the circuit configuration of the non-contact communication device according to the second embodiment. The capacitor portion of the non-contact communication device 300 includes a series resonance capacitor portion and a parallel resonance capacitor portion as in the above embodiment. The difference from the above embodiment is that the series resonance capacitor portion includes, for example, two variable capacitors VC1 and VC2, and the parallel resonance capacitor portion includes, for example, two fixed capacitance capacitors C9 and C10. Capacitors C2 and C5 for DC cut are connected in series to the variable capacitor VC1, and capacitors C3 and C6 are similarly connected in series to the variable capacitor VC2. The control unit 140 outputs the control voltage signal Vcnt to the variable capacitors VC1 and VC2 via the DAC 133 provided in the antenna drive unit 130, and controls these capacitances variably.
By variably controlling the capacitance of the series resonance capacitor portion in this way, it is possible to absorb fluctuations in the resonance frequency due to various factors, as in the first embodiment, and obtain good communication characteristics. be able to.
[Third Embodiment] FIG. 15 shows the circuit configuration of the non-contact communication device according to the third embodiment of the present invention. In this non-contact communication device 400, both the series resonance capacitor section and the parallel resonance capacitor section as the capacitor section include a variable capacitance capacitor. The parallel resonance capacitor section is composed of a variable capacitor VC1 similar to that shown in FIG. The series resonance capacitor section is composed of two variable capacitors VC2 and VC3, similar to those shown in FIG.
The control unit 140 outputs the control voltage signal Vcnt1 to the variable capacitor VC1 via the DAC (1) 135A, outputs the control voltage signal Vcnt2 to the variable capacitors VC2 and VC3 via the DAC (2) 135B, and outputs the control voltage signal Vcnt1 to the variable capacitors VC2 and VC3. These capacities are variably controlled. In the present embodiment, when the capacitance of the parallel resonance capacitor portion (variable capacitor VC1) is changed, it is necessary to change the capacitance of the series resonance capacitor portion (variable capacitors VC2, VC3) in accordance with the change. Adjustments are made.
Specifically, for example, it depends on the optimum capacitance of the series resonant capacitor (or the corresponding DAC (2) 133B) for the change in the capacitance of the parallel resonant capacitor (or the corresponding control value by DAC (1) 133A). The control value) may be associated with the table and stored in the storage unit 141 in advance as a table. Then, in the tuning process, the control unit 140 obtains the optimum control value in step 105 in the flowchart shown in FIG. 8 or step 305 in the flowchart shown in FIG. 13, and based on the table, the series resonance corresponding to the optimum control value. By obtaining the optimum control value for the capacitor section, the resonance frequency can be optimally controlled.
[Fourth Embodiment] FIG. 16 is a block diagram showing a configuration of the non-contact power supply system 2 according to a mode in which the technology of the non-contact power supply system 1 (see FIG. 1) is applied to the non-contact power supply system 2. Since data communication is also performed in the non-contact power supply system 2, this point is the same as that of the non-contact communication system 1. The difference between the non-contact power supply system 2 and the non-contact communication system 1 shown in FIG. 1 is that a power supply mode is provided, and the power receiving device 250 is provided with a charge control unit 219. Here, a method corresponding to two-way communication of transmission and reception is shown.
The antenna resonance portion 110 of the power feeding device 150 is composed of an LC resonance circuit, and has an output frequency of 100 to 200 kHz in the electromagnetic induction method known as, for example, the Qi format. When the system allows a plurality of formats as the format in this way, the oscillation frequency used by the LSI (antenna drive unit 130) and the specifications of the antenna coil in the antenna resonance unit 110 differ.
As the power feeding method of the non-contact power feeding system 2, methods such as electromagnetic induction and magnetic field resonance can be applied, and the method does not depend on the method. The power feeding device 150 sends a carrier signal and allows a current to flow through the antenna through the primary side antenna unit 111. The magnetic field generated by the current flowing through the antenna coil is magnetically coupled with the secondary side antenna unit 201 of the power receiving device 250, so that the voltage is excited to the secondary side antenna unit 201 and energy is transmitted.
In the communication state of the non-contact communication system 1, the communication distance between the transmitting device 100 and the receiving device 200 is long, and the distance changes. However, for example, in the electromagnetic induction method known as the Qi format as the power supply method, the power receiving device 250 (for example, a mobile phone device) is placed on the power supply device 150 (for example, the power supply transmission pad), so that the distance between the two is almost constant. It becomes. Such a non-contact power feeding system 2 has a resonance circuit in each of the power feeding device 150 and the power receiving device 250, and the problem that the resonance frequency shifts due to misalignment or the device to be fed is solved by the non-contact communication system 1 described above. It is the same as the problem (solved by non-contact communication system 1).
Specifically, the primary side antenna unit 111 and the secondary side antenna unit 201 are configured by a resonance circuit so as to resonate at a carrier frequency in order to perform efficient transmission. In general, energy efficiency is determined by multiplying the coupling coefficient k of the electromagnetic induction coupling by the Q value of the antenna, so it is desirable to have a large k and a high Q. However, if the Q of the resonance circuit is increased, the resonance frequency will be greatly deviated due to the variation in the constants. Therefore, it is necessary to use a very high-precision component or adjust the resonance frequency as described above.
FIG. 17 shows a sequence from detection (device detection) of a power receiving device in the power feeding device 150 to charging (power transmission). The non-contact power supply system 2 transmits energy and performs data communication by modulating the magnitude of the carrier signal, and requests device authentication and the required amount of received power. For example, in the Qi format, the power receiving device 250 modulates the carrier by load modulation, that is, by changing the magnitude of the load, thereby transmitting various data.
In the case of non-contact power feeding, the power feeding device 150 generally applies a current intermittently to the primary side antenna portion 111 for a short time of about 50 to 100 μs, and when the current value changes, the power receiving device 250 causes the power receiving device 250 to flow. Judge that it was placed. This corresponds to reaction confirmation (PING). Although it is expressed as signal strength in FIG. 17, the power feeding device 150 actually detects a change in the current of the primary side antenna unit 111. Therefore, by starting the tuning process shown in FIG. 13 in the state where the current does not change, the power supply device 150 can perform tuning in the same manner as in the above embodiment even after the product is shipped from the factory. .. If the authentication is OK, the power supply device 150 operates in the power transmission mode and transmits power to the power receiving device 250. In this case, since the power supply device 150 charges for a long time, safety is ensured by intermittently performing the recognition process.
[Other Embodiments] The present invention is not limited to the embodiments described above, and various other embodiments can be realized.
In the above embodiment, during communication, the control unit 140 controls the resonance frequency by using the optimum control value as the control voltage value for the variable capacitor VC1. However, the resonance frequency is not necessarily limited to the optimum control value, and the resonance frequency may be controlled by the control value corresponding to the minimum or maximum value of the LSI current, for example, the adjacent value. That is, the control unit 140 may control the resonance frequency with a control value in an arbitrary range including the optimum control value.
In the first and second embodiments, the parallel resonance capacitor portion is composed of one variable capacitor VC1, but may be composed of a plurality of variable capacitors.
In each of the above embodiments, for example, as shown in FIG. 2, the control unit 140 and the storage unit 141 are provided outside the antenna drive unit 130, but these are integrated in the antenna drive unit 130, for example, in the LSI. It may be provided as.
It is also possible to combine at least two feature parts among the feature parts of each form described above.
VC1, VC2, VC3 ... Variable capacitors L3 ... Antenna coil 1 ... contactless communication system 2 ... contactless power supply system 100, 300, 400 ... Transmitter (contactless communication device) 110 ... Antenna resonance part 113 ... Transmission / reception control unit 119 ... Control signal line 129 ... Input line 130 ... Antenna drive unit 131 ... Oscillator 132 ... Gain controller 133 ... DAC 134 ... ADC 135 ... Output 139 ... Control value input section 140 ... Control unit 141 ... Memory 150 ... power supply 250 ... Power receiving device
19 sheets
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Every citation, both ways
| Document | Relation | Office | Cited during |
|---|---|---|---|
| JP2008160312A | Cites | Japan | Search report |
| JP2010079451A | Cites | Japan | Search report |
| JP2011078040A | Cites | Japan | Search report |
| JP2012099968A | Cites | Japan | Search report |
| JP2013058170A | Cites | Japan | Search report |
| JP2013179556A | Cites | Japan | Search report |
3 members in 2 offices
Priority claims2
| Document | Office | Kind | Date |
|---|---|---|---|
| 2014242352 | Japan | A | |
| JP20140242352 | – | – | – |
Members3
| Document | Office | Kind | |
|---|---|---|---|
| JP5808849B1 | Japan | B1 | |
| JP2016103233AThis record | Japan | A | |
| WO2016084338A1 | World Intellectual Property Organization (WIPO) | A1 |
5 legal events, as the office reported them to INPADOC
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|---|---|---|
| Cancellation because of no payment of annual feesLAPS | LAPS | |
| Certificate of patent or registration of utility modelJAPANESE INTERMEDIATE CODE: R150R150 | R150 | |
| First payment of annual fees (during grant procedure)JAPANESE INTERMEDIATE CODE: A61A61 | A61 | |
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Numbers
- Publication
- 2016103233
- Publication, DOCDB
- 2016103233
- Publication, EPODOC
- JP2016103233
- Application
- 242352
- Application, DOCDB
- 2014242352
- Application, EPODOC
- JP20140242352
Titles2
- Japanese
- 制御方法、非接触通信装置、非接触給電装置、プログラム及び駆動回路
- English
- Control method, contactless communication device, contactless power supply device, program and drive circuit
Classification
- CPC, 3
- G06K7/10
- H04B1/59
- H04B5/48
- IPC, 4
- G06K7 10
- H04B1 59
- H04B5 48
- H04B5 02