WO2015115468A1

WO2015115468A1 - Wireless communication device

Info

Publication number: WO2015115468A1
Application number: PCT/JP2015/052326
Authority: WO
Inventors: 佐藤　直紀; 石崎　宏幸
Original assignee: シャープ株式会社
Priority date: 2014-02-03
Filing date: 2015-01-28
Publication date: 2015-08-06
Also published as: JP6165272B2; JPWO2015115468A1

Abstract

Provided is a technique of correcting the tuning frequency of the antenna of a wireless communication device to a suitable frequency regardless of the communication environment with a reader/writer device, thereby further stabilizing communication between the wireless communication device and the reader/writer device. The wireless communication device (100) communicates wirelessly with the reader/writer device (900) in a contactless manner. The wireless communication device (100) is provided with a resonant circuit (16) that receives an electromagnetic signal from the reader/writer device (900), a proximity sensor (12) for detecting proximity to the reader/writer device (900), a temperature detection circuit (13) for measuring the temperature of the communication environment of the wireless communication device (100), and a control circuit (19) for controlling communication with the reader/writer device (900). The control circuit (19) corrects the tuning frequency of the resonant circuit (16) on the basis of at least any of a distance parameter that indicates the distance to the reader/writer device (900) and a temperature parameter of the communication environment of the wireless communication device.

Description

Wireless communication device

The present disclosure relates to a wireless communication device that can communicate with a reader / writer device in a non-contact manner, and particularly relates to a technique for stabilizing communication.

A wireless communication device such as a non-contact IC (Integrated Circuit) card and a reader / writer device perform power supply, data communication, and the like by mutually transmitting and receiving electromagnetic wave signals via an antenna circuit. In order to extend the communicable distance between the wireless communication device and the reader / writer device, it is necessary to make the resonance frequencies of the antenna circuits of the wireless communication device and the reader / writer device closer. However, the resonance frequency of the wireless communication device has individual differences among the wireless communication devices due to, for example, manufacturing variations of tuning capacitors. Therefore, the resonance frequency of the wireless communication device is corrected. For example, Japanese Patent Laying-Open No. 2003-67693 (Patent Document 1) describes a non-contact IC card that can correct variations in resonance frequency without using physical means such as cutting of wiring.

JP 2003-67693 A

However, in a wireless communication device such as a non-contact IC card, depending on the usage environment, the tuning frequency of the antenna may change, and the distance in which the wireless communication device and the reader / writer device can communicate may be shortened. For example, when the reader / writer device and the wireless communication device are close to each other at a certain distance or less, the input impedance of the wireless communication device is lowered, so that the tuning frequency is shifted, and the transmission power of the wireless communication device may be lowered. In addition, for example, the tuning frequency of the antenna of the wireless communication device has a characteristic that changes according to the temperature of the operating environment of the wireless communication device. Therefore, the communication performance of the wireless communication device is affected by the temperature change in the operating environment of the wireless communication device.

The distance at which the wireless communication device and the reader / writer device can communicate may be defined in the wireless communication standard, for example. In order to comply with these wireless communication standards, the resonance frequency of the wireless communication device can be corrected in accordance with the use environment of the wireless communication device, and the distance that the wireless communication device and the reader / writer device can communicate with each other is more than a certain level. It is desirable to keep. Therefore, in a wireless communication device, a technique for further stabilizing the communication between the wireless communication device and the reader / writer device by correcting the tuning frequency of the antenna to be suitable for communication regardless of the communication environment with the reader / writer device. Is needed.

A wireless communication device according to an embodiment performs wireless communication without contact with a reader / writer device. The wireless communication device measures a temperature in a communication environment of the wireless communication device, a resonance circuit that receives an electromagnetic wave signal from the reader / writer device, a proximity sensor for measuring a distance between the reader / writer device and the wireless communication device. And a control unit for controlling communication with the reader / writer device. The control unit acquires a distance parameter indicating a distance between the reader / writer device and the wireless communication device from the proximity sensor, acquires a temperature parameter indicating a temperature in a communication environment of the wireless communication device from the temperature sensor, and determines the distance parameter and the temperature. The tuning frequency of the resonant circuit is corrected based on at least one of the parameters.

According to the above-described embodiment, regardless of the installation environment of the reader / writer device, the tuning frequency of the antenna of the wireless communication device can be made suitable for communication, and communication between the wireless communication device and the reader / writer device is possible. Is more stable.

The above and other objects, features, aspects and advantages of the present invention will become apparent from the following detailed description of the present invention which is to be understood in connection with the accompanying drawings.

1 is a block diagram schematically showing a configuration of a wireless communication device 100 according to a first embodiment. It is a figure which shows the data structure of the correction table. 2 is a diagram illustrating a communication environment between a wireless communication device 100 and a reader / writer device 900. FIG. 4 is a flowchart showing an operation of the wireless communication device 100. 6 is a block diagram schematically showing a configuration of a wireless communication apparatus 200 according to a second embodiment. FIG. It is a figure which shows the data structure of the correction table. 7 is a diagram illustrating a data structure of a correction table 93 referred to by the control circuit 19 in order to determine the correction voltage value of the variable capacitor 63 by weighting the detection result of the operating temperature of each circuit of the wireless communication device 200. FIG. 6 is a block diagram schematically showing a configuration of a wireless communication apparatus 300 according to a third embodiment. FIG. FIG. 4 is a diagram showing a temperature table for performing frequency adjustment based on a temperature difference between a temperature when an antenna resonant frequency of wireless communication apparatus 300 is set and a temperature when wireless communication apparatus 300 is operating.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

<Embodiment 1>
<Functional configuration>
FIG. 1 is a block diagram schematically showing a configuration of radio communication apparatus 100 according to the first embodiment. Referring to FIG. 1, a wireless communication device 100 includes a memory 11, a proximity sensor 12, a temperature detection circuit 13, a modulation circuit 14, a power amplifier 15, a resonance circuit 16, a detection circuit 17, and a reception circuit. 18 and a control circuit 19. The resonance circuit 16 includes an antenna tuning circuit 60 and a loop antenna 61. The antenna tuning circuit 60 includes a tuning capacitor 62 and a variable capacitor 63.

The wireless communication device 100 is, for example, an electronic device such as an IC card realized by RFID (Radio Frequency Identification) technology, a smartphone equipped with NFC (Near Field Communication) technology, a tablet terminal, or a digital camera. The wireless communication device 100 transmits and receives information to and from the reader / writer device (reader / writer device 900) by wireless communication at a short distance (for example, about several centimeters to several meters). The wireless communication device 100 is, for example, a passive IC card that does not include a battery, receives an electromagnetic wave signal from the outside, and uses the received radio wave as an operating voltage. Not limited to this, an active (active) wireless communication device that incorporates a battery and emits radio waves with electric power from the battery during communication may be used. The reader / writer device 900 performs power supply and communication with the wireless communication device 100 such as an IC card.

As will be described later, the wireless communication device 100 includes (1) a communication distance between the wireless communication device 100 and the reader / writer device 900, and (2) a temperature in a communication environment between the wireless communication device 100 and the reader / writer device 900. Based on at least one of the above, the tuning frequency of the resonance circuit of the wireless communication apparatus 100 is corrected. (1) As the wireless communication device 100 and the reader / writer device 900 come close to each other and the communication distance between the wireless communication device 100 and the reader / writer device 900 becomes shorter, the tuning frequency of the resonance circuit of the wireless communication device 100 becomes a frequency. , And the transmission power from the antenna of the wireless communication apparatus 100 decreases. Therefore, the wireless communication device 100 corrects the tuning frequency of the resonance circuit according to the communication distance between the wireless communication device 100 and the reader / writer device 900. For example, the wireless communication device 100 detects the communication distance between the wireless communication device 100 and the reader / writer device 900, and when the communication distance is equal to or less than a certain distance, increases the tuning frequency of the resonance circuit and Increase transmission power. In addition, when the communication distance between the wireless communication apparatus 100 and the reader / writer apparatus 900 is a certain distance or more, the wireless communication apparatus 100 decreases the tuning frequency and decreases the transmission power from the antenna. (2) The tuning frequency of the antenna of the resonance circuit of the wireless communication device 100 has a characteristic that changes according to temperature. Therefore, a change in temperature in the communication environment between the wireless communication device 100 and the reader / writer device 900 may affect the communication performance. For example, the tuning frequency optimized at a certain temperature may be shifted due to a change in temperature in the communication environment between the wireless communication device 100 and the reader / writer device 900, and communication performance may deteriorate. On the other hand, the wireless communication device 100 has a configuration in which a tuning capacitor and a variable capacitor are connected in parallel in a resonance circuit. The variable capacitance capacitor has a characteristic that the capacitance value decreases according to the magnitude of the applied control voltage, and the capacitance value increases as the ambient temperature rises. Therefore, the wireless communication apparatus 100 compensates for the temperature characteristics of the variable capacitor by increasing the control voltage applied to the variable capacitor (correcting the applied control voltage) in response to a rise in temperature in the communication environment. As a result, the tuning frequency of the resonant circuit can be compensated.

The memory 11 is a non-volatile memory, and is read and written by a command from a control circuit 19 (CPU (Central Processing Unit)). The memory 11 stores information indicating the magnitude of the control voltage applied to the variable capacitor 63.

The proximity sensor 12 is a sensor for detecting that the reader / writer device 900 as the detection target and the wireless communication device 100 are close to each other. The proximity sensor 12 indicates that the reader / writer device 900 is in close proximity without contacting the reader / writer device 900, for example, an electrostatic generated between the detection body (reader / writer device 900) and the proximity sensor 12. It is detected by an electrical method such as detecting a change in capacitance.

The temperature detection circuit 13 is a circuit for detecting a temperature in an environment in which the wireless communication device 100 and the reader / writer device 900 communicate. The temperature detection circuit 13 detects, for example, a change in resistance value with respect to a temperature change. The temperature is detected by a method such as the above, and the temperature outside the wireless communication apparatus 100 is measured.

The modulation circuit 14 up-converts the transmission baseband signal received from the control circuit 19 into a radio frequency band signal.

The power amplifier 15 amplifies the signal up-converted by the modulation circuit 14 and supplies the amplified signal to the resonance circuit 16.

The resonance circuit 16 includes a loop antenna 61, receives an electromagnetic wave signal from the outside of the wireless communication device 100 by the loop antenna 61, and transmits a signal transmitted by the wireless communication device 100 to the outside of the wireless communication device 100. As shown in FIG. In the resonance circuit 16, a tuning capacitor 62 and a variable capacitor 63 are connected in parallel. The tuning capacitor C1 of the tuning capacitor 62 is fixed, and the correction capacitor C2 of the variable capacitor 63 is variable. The variable capacitor 63 has a capacitance value that decreases as the control voltage applied to the variable capacitor 63 increases under the control of the control circuit 19. The wireless communication device 100 can switch the resonance frequency of the resonance circuit 16 by controlling the correction capacitor C2 of the variable capacitor 63 that is a variable capacitor. The configuration for controlling the correction capacitor C2 of the variable capacitor 63 is not limited to these. For example, the variable capacitor 63 includes capacitors C21, C22,..., A capacitor C2n, and n capacitors, It is good also as including the transistor arrange | positioned corresponding to each of these capacitors. The control circuit 19 selects any one of the capacitors of the variable capacitor 63 by turning on one of these transistors and turning off the other transistor.

The detection circuit 17 detects a received signal received from the reader / writer device 900 by the wireless communication device 100 communicating wirelessly with the reader / writer device 900, converts the received signal into a DC voltage, and generates a power supply voltage of the wireless communication device 100 To do.

The reception circuit 18 converts the signal output from the detection circuit 17 into a reception baseband signal that can be processed by the control circuit 19.

The control circuit 19 includes a CPU, a ROM (Read Only Memory), a RAM (Random Access Memory), etc., operates according to a program, and controls the correction capacitor C2 of the variable capacitor 63, thereby allowing the wireless communication device 100 and an external device to operate. Controls wireless communication with the device. The control circuit 19 reads the correction table 91 from the memory 11 and stores it. The correction table 91 includes the temperature in the communication environment of the wireless communication device 100 (for example, the temperature outside the wireless communication device 100), the distance between the wireless communication device 100 and the reader / writer device 900, and the correction capacity of the variable capacitor 63. It is the table which matched with the information for selecting C2. That is, the control circuit 19 acquires a distance parameter indicating the distance between the reader / writer device 900 and the wireless communication device 100 from the proximity sensor 12, and sets the temperature parameter indicating the temperature in the communication environment of the wireless communication device 100 to the temperature detection circuit 13. The correction capacity C2 of the variable capacitor 63 is controlled by referring to the acquired distance parameter and temperature parameter and the correction table 91. Thereby, the wireless communication device 100 corrects the tuning frequency of the resonance circuit 16. Accordingly, the tuning frequency of the antenna of the wireless communication device 100 can be made suitable for communication regardless of the installation environment of the reader / writer device 900, and communication between the wireless communication device 100 and the reader / writer device 900 can be performed. Is more stable.

<Data>
FIG. 2 is a diagram illustrating the data structure of the correction table 91. As shown in FIG. 2, the correction table 91 includes a number 101, an ambient temperature 102, a proximity distance 103, and a correction voltage value 104 in one record. The correction table 91 is a table that the control circuit 19 refers to in order to correct the tuning frequency of the resonance circuit 16.

Number 101 is information for identifying each record included in the correction table 91.
The ambient temperature 102 is information for comparison with the output result of the temperature detection circuit 13 in order to correct the tuning frequency of the antenna of the wireless communication apparatus 100. The correction table 91 divides the temperature outside the wireless communication device 100 at a certain range at the ambient temperature 102. In the ambient temperature 102, for example, a temperature range “temperature T0 to T1” indicates a case where the temperature outside the wireless communication device 100 is not less than the temperature T0 and not more than the temperature T1. The correction table 91 is a table in which each external temperature range (ambient temperature 102) is associated with information (correction voltage value 104) for selecting the correction capacitor C2 of the variable capacitor 63.

The proximity distance 103 is information for the control circuit 19 to compare with the output result of the proximity sensor 12 in order to correct the tuning frequency of the antenna of the wireless communication apparatus 100. The correction table 91 divides the distance between the wireless communication device 100 and the reader / writer device 900 at a fixed distance at the proximity distance 103. In the proximity distance 103, for example, the distance “greater than the distance L1” indicates a case where the distance between the wireless communication device 100 and the reader / writer device 900 is larger than the distance L1. The correction table 91 associates the distance (proximity distance 103) between the wireless communication device 100 and the reader / writer device 900 with information (correction voltage value 104) for selecting the correction capacitor C2 of the variable capacitor 63. It is a table.

The correction voltage value 104 indicates a correction value for the control voltage applied to the variable capacitor 63. For example, the wireless communication device 100 optimizes the tuning frequency at a certain temperature, and in this case, the control voltage to be applied to the variable capacitor 63 is stored in the memory 11, and the temperature change in the communication environment of the wireless communication device 100, and The correction value of the voltage corresponding to the proximity distance between the wireless communication device 100 and the reader / writer device 900 is stored as the correction voltage value 104.

FIG. 3 is a diagram illustrating a communication environment between the wireless communication apparatus 100 and the reader / writer apparatus 900. FIG. 3A shows a case where the distance between the wireless communication apparatus 100 and the reader / writer apparatus 900 is a distance “L1” or more and the temperature in the communication environment is the ambient temperature “T1”. In the case shown in FIG. 3A, the control circuit 19 refers to the correction table 91, and from the record corresponding to the distance “greater than the distance L1” shown in the proximity distance 103, the temperature in the communication environment of the wireless communication device 100 Accordingly, the correction voltage value of the control voltage applied to the variable capacitor 63 is selected. As a result, the wireless communication device 100 corrects the tuning frequency of the antenna of the resonance circuit.

FIG. 3B shows a case where the distance between the wireless communication device 100 and the reader / writer device 900 is close to the distance “L2” and the temperature in the communication environment is the ambient temperature “T2”. In the case shown in FIG. 3B, the control circuit 19 refers to the correction table 91 and selects from the records corresponding to the distance “distance L2 to L1” (greater than the distance L2 and smaller than the distance L1) shown in the proximity distance 103. The correction voltage value of the control voltage applied to the variable capacitor 63 is selected according to the temperature in the communication environment of the wireless communication device 100. As a result, the wireless communication device 100 corrects the tuning frequency of the antenna of the resonance circuit.

<Operation>
With reference to FIG. 4, the operation of radio communication apparatus 100 according to the first embodiment will be described. FIG. 4 is a flowchart showing the operation of the wireless communication device 100. The wireless communication device 100 approaches the reader / writer device 900, receives an electromagnetic wave signal from the reader / writer device 900, and starts operation using the received radio wave as an operating voltage. In order for the wireless communication device 100 to operate stably, it is assumed that an operating voltage equal to or higher than a certain voltage is required.

In step S401, when the wireless communication device 100 and the reader / writer device 900 approach each other and the operating voltage rises above a certain voltage (YES in step S401), the wireless communication device 100 performs the process of step S403. If not (NO in step S401), the process waits until the operating voltage rises to a constant voltage.

In step S403, the control circuit 19 activates the temperature detection circuit 13, and causes the temperature detection circuit 13 to output the temperature measurement result in the communication environment between the wireless communication device 100 and the reader / writer device 900.

In step S405, the control circuit 19 causes the proximity sensor 12 to output the measurement result of the proximity distance between the wireless communication device 100 and the reader / writer device 900.

In step S407, the control circuit 19 measures the measurement result of the temperature detection circuit 13 (temperature parameter indicating the temperature in the communication environment between the wireless communication device 100 and the reader / writer device 900) and the measurement result of the proximity sensor 12 (wireless communication device). The correction table 91 is referred to based on a distance parameter indicating a distance between the reader 100 and the reader / writer device 900.

In step S409, the control circuit 19 specifies a record for correcting the control voltage applied to the variable capacitor 63 by referring to the correction table 91 using the temperature parameter and the distance parameter, and the specified record The correction voltage value 104 is read out.

In step S411, the control circuit 19 reads information indicating the magnitude of the control voltage to be applied to the variable capacitor 63, stored in the memory 11, and the correction voltage value 104 indicates the read control voltage. A voltage value to which the voltage value is applied is supplied to the variable capacitor 63 of the antenna tuning circuit 60.

In step S413, when the operating voltage of the wireless communication device 100 becomes equal to or lower than a predetermined voltage due to the separation of the wireless communication device 100 and the reader / writer device 900 (YES in step S413), the control circuit 19 If not (NO in step S413), the processes in and after step S405 are repeated.

In step S415, the control circuit 19 turns off the operation of the temperature detection circuit 13, and performs the process of step S401.

In step S409, the control circuit 19 specifies a record for correcting the control voltage applied to the variable capacitor 63 by referring to the correction table 91 using either the temperature parameter or the distance parameter. The correction voltage value 104 of the specified record may be read out.

<Summary of Embodiment 1>
The wireless communication device 100 according to the first embodiment corrects the tuning frequency of the antenna in accordance with the temperature in the communication environment with the reader / writer device 900 (the temperature outside the wireless communication device 100). The wireless communication device 100 measures the distance from the reader / writer device 900 and corrects the tuning frequency according to the distance. Therefore, according to the wireless communication apparatus 100 of the first embodiment, the tuning frequency of the antenna of the wireless communication apparatus 100 can be corrected to an optimum frequency regardless of the installation environment of the reader / writer apparatus 900, and the reader / writer apparatus Communication with 900 is stabilized.

<Embodiment 2>
FIG. 5 is a block diagram schematically showing the configuration of radio communication apparatus 200 according to the second embodiment. Referring to FIG. 5, radio communication apparatus 200 includes a configuration of radio communication apparatus 100 according to the first embodiment, temperature detection circuit 30, temperature detection circuit 35, temperature detection circuit 39, and operating point adjustment circuit 41. including. The wireless communication apparatus 200 stores a correction table 92 in the memory 11.

The radio communication apparatus 100 according to the first embodiment detects the temperature outside the radio communication apparatus 100 and corrects the tuning frequency of the antenna. The radio communication apparatus 200 according to the second embodiment is similar to the radio communication apparatus 200. The operating temperature of each circuit is detected, and the tuning frequency of the antenna is corrected according to these detection results. The circuits for which the operating temperature is detected are, for example, the antenna tuning circuit 60, the power amplifier 15, and the control circuit 19. The temperature detection circuit 30 is a sensor for detecting the operating temperature of the antenna tuning circuit 60, and outputs a signal value corresponding to the temperature. The temperature detection circuit 35 is a sensor for detecting the temperature of the power amplifier 15. The temperature detection circuit 39 is a sensor for detecting the temperature of the control circuit 19.

When the continuous use time of the wireless communication device 200 is increased, the power amplifier 15 is self-heated, the output voltage of the power amplifier 15 is lowered, and the communication distance of the wireless communication device 200 may be shortened. Therefore, the wireless communication device 200 measures the temperature of the power amplifier 15 by the temperature detection circuit 35 disposed in the vicinity of the power amplifier 15. The power amplifier 15 of the wireless communication apparatus 200 operates by switching between a normal mode in which the output voltage is normal and a high output mode in which the output voltage is relatively large. The wireless communication device 200 stores the temperature in the vicinity of the power amplifier 15 and the mode for operating the power amplifier 15 in the memory 11 in association with each other. The operating point adjustment circuit 41 is a circuit that controls whether the power amplifier 15 is operated in the normal mode or the high output mode. When the control circuit 19 receives the measurement result of the temperature of the power amplifier 15 from the temperature detection circuit 35 and determines that the temperature of the power amplifier 15 is equal to or higher than the threshold value, the control circuit 19 operates the power amplifier 15 in the high output mode, and the power amplifier 15 If it is determined that the temperature does not exceed the threshold value, the power amplifier 15 is operated in the normal mode. Thereby, the wireless communication device 200 can correct the decrease in the output voltage of the power amplifier 15 due to the temperature increase of the power amplifier 15, and can avoid the decrease in the communication distance of the wireless communication device 200.

<Data>
With reference to FIG. 6, a data structure of data used by wireless communication apparatus 200 will be described. FIG. 6 is a diagram illustrating the data structure of the correction table 92. As shown in FIG. 6, the correction table 92 includes a number 201, an ambient temperature 202, a power amplifier temperature 203, a proximity distance 204, and a correction voltage value 205 in one record. The correction table 92 is used for the control circuit 19 to correct the tuning frequency of the resonance circuit 16 according to the temperature of each circuit of the wireless communication device 200 and the distance between the wireless communication device 200 and the reader / writer device 900. It is a table to refer to.

The number 201 is information for identifying each record included in the correction table 92.
The ambient temperature 202 indicates a temperature range outside the wireless communication apparatus 200 corresponding to the measurement result of the temperature detection circuit 13. The power amplifier temperature 203 divides the temperature of the power amplifier 15 into a certain range corresponding to the measurement result of the temperature detection circuit 35.

The proximity distance 204 is information for the control circuit 19 to compare with the output result of the proximity sensor 12 in order to correct the tuning frequency of the antenna of the wireless communication apparatus 200.

The correction voltage value 205 indicates a correction value for the control voltage applied to the variable capacitor 63.
<Operation>
An operation of the wireless communication device 200 will be described. In step S409 of FIG. 4 described in the first embodiment, the control circuit 19 determines the variable capacitance based on the temperature parameter of each circuit output from the temperature detection circuit 13, the temperature detection circuit 35, and the like and the correction table 92. A record for correcting the control voltage applied to the capacitor 63 is specified, and the correction voltage value 205 of the specified record is read. In response to the read correction voltage value 205, the control circuit 19 applies a control voltage to the variable capacitor 63.

In step S409 of FIG. 4 described in the first embodiment, the control circuit 19 sets one of the temperature parameter (the temperature outside the wireless communication device 200 and the temperature of each circuit of the wireless communication device 200) and the distance parameter. By using the correction table 92 and referring to it, the record for correcting the control voltage applied to the variable capacitor 63 may be specified, and the correction voltage value 205 of the specified record may be read out. In addition, the control circuit 10 determines a correction voltage value for correcting the control voltage applied to the variable capacitor 63 using the temperature of at least one of the circuits of the wireless communication apparatus 200 as the temperature parameter. It is good as well.

<Modification of Embodiment 2>
The wireless communication device 200 may determine the correction voltage value of the variable capacitor 63 by weighting the detection result of the operation temperature of each circuit. In this case, the wireless communication apparatus 200 stores a correction table 93 to be described later in the memory 11 corresponding to the weighting.

FIG. 7 is a diagram illustrating a data structure of the correction table 93 referred to by the control circuit 19 in order to determine the correction voltage value of the variable capacitor 63 by weighting the detection result of the operating temperature of each circuit of the wireless communication device 200. is there. As illustrated in FIG. 7, the correction table 93 includes a number 301, a weighted temperature parameter 302, a proximity distance 303, and a correction voltage value 304 in one record. For example, the output result of the temperature detection circuit 13 (operation temperature outside the wireless communication apparatus 200) is the temperature parameter Tx, the output result of the temperature detection circuit 30 (operation temperature of the antenna tuning circuit 60) is the temperature parameter Tc, and the temperature detection circuit 35. When the output result (operating temperature of the power amplifier 15) is a temperature parameter Tp, and the output result (operating temperature of the control circuit 19) of the temperature detection circuit 39 is a temperature parameter Tr, the control circuit 19 uses the temperature parameter after weighting calculation. Ta is calculated by Ta = (α × Tx) + (β × Tp) + (γ × Tr) + (δ × Tc). Here, it is assumed that the coefficient α, the coefficient β, the coefficient γ, and the coefficient δ are constants.

A number 301 is information for identifying each record included in the correction table 93.
The post-weighting temperature parameter 302 divides the temperature for each fixed range corresponding to the post-weighting temperature parameter Ta of the wireless communication apparatus 200.

The proximity distance 303 is information for the control circuit 19 to compare with the output result of the proximity sensor 12 in order to correct the tuning frequency of the antenna of the wireless communication apparatus 200.

The correction voltage value 304 indicates a correction value for the control voltage applied to the variable capacitor 63.
<Operation of Modified Example of Embodiment 2>
The operation of the modification of the second embodiment will be described. In step S409 of FIG. 4 described in the first embodiment, the control circuit 19 performs weighting calculation based on the temperature parameter of each circuit output from the temperature detection circuit 13, the temperature detection circuit 35, and the like. The temperature parameter Ta is calculated. The control circuit 19 specifies a record for correcting the control voltage to be applied to the variable capacitor 63 based on the calculated temperature parameter Ta after the weighting calculation and the correction table 93. The correction voltage value 304 is read out. In response to the read correction voltage value 304, the control circuit 19 applies a control voltage to the variable capacitor 63.

In step S409 of FIG. 4 described in the first embodiment, the control circuit 19 refers to the correction table 93 by using either the temperature parameter or the distance parameter after the weighting calculation, thereby causing the variable capacitor 63 to A record for correcting the applied control voltage may be specified, and the correction voltage value 304 of the specified record may be read.

<Embodiment 3>
A wireless communication apparatus 300 according to the third embodiment will be described. The entire circuit including the antenna of the wireless communication device 300 has a negative frequency characteristic with respect to the temperature in the communication environment of the wireless communication device 300. That is, when the adjustment for setting the resonance frequency of the wireless communication device 300 is performed under a high temperature environment, when the temperature decreases, the resonance frequency of the antenna of the wireless communication device 300 increases, and the wireless communication device 300 Communication with the reader / writer device 900 may not be stable and the communication distance may be reduced. Further, when the adjustment for setting the resonance frequency of the wireless communication device 300 is performed under a low temperature environment, when the temperature rises, the resonance frequency of the antenna of the wireless communication device 300 decreases, and the wireless communication device 300 Communication with the reader / writer device 900 may not be stable and the communication distance may be reduced.

Therefore, the wireless communication device 300 performs frequency adjustment based on the temperature difference during operation of the wireless communication device 300 with respect to the temperature when the resonance frequency of the antenna of the wireless communication device 300 is set.

FIG. 8 is a block diagram schematically showing a configuration of radio communication apparatus 300 according to the third embodiment. The wireless communication device 300 stores the initial adjustment temperature information 95 in the memory 11. The initial adjustment temperature information 95 is information indicating the temperature when the resonance frequency of the antenna of the wireless communication apparatus 300 is set.

FIG. 9 is a diagram illustrating a temperature table for performing frequency adjustment based on a temperature difference between the temperature when the antenna resonant frequency of the wireless communication apparatus 300 is set and the temperature during operation of the wireless communication apparatus 300. . FIG. 9A corresponds to the temperature when the wireless communication device 300 is operating and the shift amount to shift the frequency when the temperature when the resonance frequency of the antenna of the wireless communication device 300 is set is 30 degrees. It is the attached temperature table. FIG. 9B associates the temperature during operation of the wireless communication device 300 with the frequency shift amount when the temperature when the resonance frequency of the antenna of the wireless communication device 300 is set is 30 degrees. It is a graph. As shown in FIG. 9A and FIG. 9B, the wireless communication device 300 changes the frequency by the shift amount “−3.4 kHz” every time the temperature during the operation of the wireless communication device 300 increases. The resonance frequency is adjusted by shifting the distance.

The wireless communication apparatus of the present invention is realized by a processor and a program executed on the processor. The program for realizing the present invention is provided by transmission / reception using a network via a communication interface.

The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

11 memory, 12 proximity sensor, 13 temperature detection circuit, 14 modulation circuit, 15 power amplifier, 16 resonance circuit, 17 detection circuit, 18 reception circuit, 19 control circuit, 30 temperature detection circuit, 35 temperature detection circuit, 39 temperature detection circuit 41, operating point adjustment circuit, 60 antenna tuning circuit, 61 loop antenna, 62 tuning capacitor, 63 variable capacitor, 91 correction table, 92 correction table, 93 correction table, 95 initial adjustment temperature information, 100, 200, 300 Wireless communication device, 900 reader / writer device.

Claims

A wireless communication device that performs wireless communication without contact with a reader / writer device,
A resonant circuit for receiving an electromagnetic wave signal from the reader / writer device;
A proximity sensor for measuring a distance between the reader / writer device and the wireless communication device;
A temperature sensor for measuring a temperature in a communication environment of the wireless communication device;
A control unit for controlling communication with the reader / writer device,
The control unit acquires a distance parameter indicating a distance between the reader / writer device and the wireless communication device from the proximity sensor, and acquires a temperature parameter indicating a temperature in a communication environment of the wireless communication device from the temperature sensor. A wireless communication device configured to correct a tuning frequency of the resonant circuit based on at least one of the distance parameter and the temperature parameter.
Measuring the temperature in the communication environment of the wireless communication device by the temperature sensor includes measuring the temperature outside the wireless communication device,
The wireless communication device according to claim 1, wherein the control unit corrects the tuning frequency based on a temperature parameter corresponding to a temperature outside the wireless communication device.
Measuring the temperature in the communication environment of the wireless communication device by the temperature sensor includes measuring the temperature of at least one of the circuits arranged on the circuit board of the wireless communication device,
The wireless communication apparatus according to claim 1, wherein the control unit corrects the tuning frequency based on a temperature parameter corresponding to a temperature of the circuit arranged on a circuit board of the wireless communication apparatus.
The wireless communication device stores an initial temperature parameter indicating a temperature at the time of setting the tuning frequency of the resonant circuit in a memory,
The control unit corrects the tuning frequency based on a difference between a temperature in a communication environment of the wireless communication device indicated by the temperature parameter and a temperature at the time of setting indicated by the initial temperature parameter. 4. The wireless communication device according to claim 1.
The temperature sensor includes one for measuring the temperature of a power amplifier disposed on a circuit board of the wireless communication device,
The control unit is configured to increase the output power of the power amplifier compared to an output voltage when the temperature of the power amplifier is equal to or lower than a threshold when the temperature of the power amplifier is equal to or higher than a threshold. The wireless communication device according to any one of claims 1 to 4.