JP4959659B2 - Data carrier leader / writer - Google Patents

Description

The present invention relates to a data carrier reader / writer having an APC (Automatic Power Control) function.

Conventionally, a transmission circuit that modulates a local signal with an input signal and further amplifies the signal with an amplifier is supplied to an antenna, and the power level of the transmission signal output from the transmission circuit to the antenna is controlled to a target value. In a wireless communication device including an APC circuit, the temperature of the transmission circuit is measured, and the target value is corrected according to the measured temperature, thereby correcting variations in circuit components with respect to the temperature change, and A technique for controlling the output power to be constant is already known (for example, see Patent Document 1).
Japanese Utility Model Publication No. 5-9018

  However, even a conventional wireless communication apparatus having a target value temperature correction function still has a technical problem to be solved in the following points. That is, in the case of a wireless communication apparatus using an APC circuit, the power level of the transmission signal can be brought close to the target value as time passes. However, the time required to reach the target value varies. This variation is caused by the temperature characteristics of the transmission circuit.

  For example, assume that the temperature characteristics of the transmission circuit are as follows. That is, when 100 mV (millivolt) is supplied to the transmission circuit when the temperature is 0 degrees, the output power becomes the target value, and when 200 mV is supplied to the transmission circuit when the temperature is 20 degrees, the output power becomes the target value and the temperature is 40 When power is supplied to the transmission circuit at 380 mV, the output power becomes the target value. This means that the transmission circuit can obtain a target output power with a small voltage when the temperature is low, but has a characteristic that the voltage must be increased as the temperature becomes higher. Some circuit components constituting the transmission circuit may have the opposite characteristics.

  In the conventional wireless communication apparatus, the initial voltage supplied to the transmission circuit at the start of transmission is fixed regardless of the temperature characteristics of the transmission circuit. Therefore, if the temperature of the transmission circuit at the start of transmission is close to the temperature at which the output power reaches the target value when the initial voltage is supplied, the target value can be reached in a relatively short time. In such a case, it takes a long time to reach the target value. As a result, communication efficiency has been reduced.

The present invention has been made based on such circumstances, and the object of the present invention is to reduce the time required for the power level of the transmission signal to reach the target level regardless of the temperature environment, thereby improving the communication efficiency. It is an object of the present invention to provide a data carrier reader / writer capable of improving the performance.

The present invention detects a power level of a transmission signal output from the transmission unit to the antenna, and outputs the transmission signal obtained by modulating and amplifying the local signal to the antenna. A temperature measuring means for measuring the temperature of the transmission section in a data carrier reader / writer comprising an output adjustment means for adjusting the amplification factor of the transmission section by varying the voltage fed to the transmission section so as to be a value; In advance, the supply voltage data to the transmission unit when the target value is obtained as the power level of the transmission signal when the temperature of the transmission unit is the corresponding data value is stored in advance in association with the temperature data of the plurality of stages. Search storage means, upon receipt of a read command or a write command for data carriers, acquires the temperature measured by the temperature measuring means, the storage means at this acquired temperature Te, the power supply voltage data corresponding to the temperature and voltage initial value determining means for determining an initial value of the voltage fed to the transmission unit, to the data carrier with a voltage of the initial value determined by the voltage initial value determining means And a control means for performing writing or reading of data .

  According to the present invention in which such a measure is taken, it is possible to shorten the time required until the power level of the transmission signal reaches the target level regardless of the temperature environment, and it is possible to improve the communication efficiency. .

The best mode for carrying out the present invention will be described below with reference to the drawings.
In this embodiment, wireless communication is performed with an RFID-compatible storage medium (hereinafter referred to as a data carrier) called a wireless tag, an RF tag, a responder, a contactless communication card, an RF card, etc. This is a case where the present invention is applied to a reader / writer that can write data on a data carrier or read data on the data carrier.

(First embodiment)
The main configuration of the reader / writer in this embodiment is shown in the block diagram of FIG. A reader / writer, which is an aspect of the wireless communication apparatus of the present invention, includes a transmission / reception control apparatus 1 and an antenna 2 connected to the transmission / reception control apparatus 1. The transmission / reception control device 1 includes an interface unit 11, a control unit 12, a transmission unit 13, a reception unit 14, a circulator 15, an APC (Automatic Power Control) circuit 16, a thermistor 17, an A / D (Analog / Digital) converter 18, and a voltage adjustment. A circuit 19 and a nonvolatile memory 20 are provided.

The interface unit 11 manages data communication between the external host device and the control unit 12.
The transmission unit 13 generates a transmission signal to the data carrier under the control of the control unit 12 and outputs the transmission signal to the antenna 2. The transmission unit 13 includes an oscillator 131, a modulator 132, and an amplifier 133. The oscillator 131 outputs a local signal that is a carrier wave to the modulator 132. The modulator 132 modulates the local signal with the input signal from the control unit 12. The amplifier 133 amplifies the modulation signal modulated by the modulator 132. The modulated signal amplified by the amplifier 133 is output as a transmission signal and supplied to the antenna 2 via the circulator 15.

The circulator 15 is also called a directional coupler, and outputs a transmission signal from the transmission unit 13 to the antenna 2 and outputs a radio wave signal received by the antenna 2 to the reception unit 14.
The receiving unit 14 receives a data signal from the data carrier via the antenna 2 and outputs the data signal to the control unit 12. The receiving unit 14 includes a demodulator 141 and an amplifier 142. The demodulator 141 demodulates the received data signal from the radio wave signal from the antenna 2. The amplifier 142 amplifies the reception data signal demodulated by the demodulator 141. The reception data signal amplified by the amplifier 142 is output to the control unit 12.

The APC circuit 16 detects the power level of the transmission signal output from the transmission unit 13 to the antenna 2. Then, the power level is converted into a voltage value (mV) and given to the control unit 12.
The thermistor 17 measures the internal temperature of the transmission / reception control device 1 and is provided in the vicinity of the transmission unit 13. Here, the thermistor 17 functions as a temperature measurement unit that measures the temperature of the transmission unit 13. The thermistor 17 supplies a temperature signal to the A / D converter 18. The A / D converter 18 converts the temperature signal from the thermistor 17, which is an analog signal, into a digital signal and supplies it to the control unit 12.

  The voltage adjustment circuit 19 variably adjusts the voltage supplied to the amplifier 133 in the transmission unit 13 under the control of the control unit 12. The amplifier 133 varies the amplification factor by the voltage supplied through the voltage adjustment circuit 19. When the amplification factor of the amplifier 133 changes, the power level of the transmission signal changes.

  The nonvolatile memory 20 is a rewritable programmable ROM (Read Only Memory) such as a flash memory. The reader / writer stores a setting table 30 in the nonvolatile memory 20. The data structure of the setting table 30 is shown in FIG. As shown in the figure, the setting table 30 associates the temperature range from 0 ° C. to 45 ° C. with the measured temperature T (° C.) divided into 10 stages at 5 ° C. intervals, and the transmission unit initial voltage M (mV). The APC target value N (mV) is stored in advance and constitutes storage means.

  The setting table 30 is created at the final test stage before the reader / writer is shipped as a product, and is stored in the nonvolatile memory 20. The test is executed by the person in charge according to the following procedure.

  First, the person in charge connects the reader / writer to be tested to a dedicated measuring jig. The jig includes the temperature of the transmitter 13 of the reader / writer, the power output from the transmitter 13 to the antenna 2, the output voltage supplied from the APC circuit 16 to the controller 12, and the amplifier from the voltage adjustment circuit 19 The voltage supplied to 133 is accurately measured.

  Next, the person in charge adjusts the temperature environment in which the reader / writer is placed, and sets the temperature of the transmission unit 13 to the minimum temperature 0 ° C. of the measured temperature T set in the setting table 30. When the temperature of the transmitter 13 reaches 0 ° C., the person in charge is fed from the voltage adjustment circuit 19 to the amplifier 133 until the power output from the transmitter 13 to the antenna 2 reaches a target value, for example, 100 mW. Increase or decrease the voltage. If the output power from the transmission unit 13 reaches the target value, the person in charge sets the power supply voltage from the voltage adjustment circuit 19 when the target value is reached as the transmission unit initial voltage M0 for the measured temperature T = 0 ° C. Record 30. Further, the output voltage from the APC circuit 16 when the target value is reached is recorded in the setting table 30 as the APC target value N0 for the measured temperature T = 0 ° C.

  Next, the person in charge adjusts the temperature environment of the reader / writer, and raises the temperature of the transmitter 13 to the measurement temperature of 5 ° C. at the next stage. When the temperature of the transmission unit 13 reaches 5 ° C., the person in charge changes the voltage supplied from the voltage adjustment circuit 19 to the amplifier 133 until the power output from the transmission unit 13 to the antenna 2 reaches the target value again. Increase or decrease. If the output power from the transmission unit 13 reaches the target value, the person in charge sets the power supply voltage from the voltage adjustment circuit 19 when the target value is reached as the transmission unit initial voltage M5 for the measured temperature T = 5 ° C. Record 30. Further, the output voltage from the APC circuit 16 when the target value is reached is recorded in the setting table 30 as the APC target value N5 for the measured temperature T = 5 ° C.

  Thereafter, every time the temperature of the transmitter 13 is increased by 5 ° C., the same measurement is performed, and the measurement values (the power supply voltage from the voltage adjustment circuit 19 and the output voltage from the APC circuit 16) are acquired, and the measured temperature The process of recording in the setting table 30 as the transmitter initial voltage M and the APC target value N for T is repeated. In this way, if the same processing is performed on the maximum temperature 45 ° C. of the measured temperature T, the setting table 30 suitable for the temperature characteristics of the transmitter 13 of the reader / writer is created. The setting table 30 is stored in the non-volatile memory 20 of the reader / writer via the device.

  The control unit 12 is mainly composed of a CPU, a ROM, a RAM, and the like. In the RAM area, as shown in FIG. 3, a work area is formed in which the transmitter initial voltage A and the APC target value B are stored in a rewritable manner.

  The control unit 12 executes read / write processing on the data carrier according to the control procedure shown in the flowchart of FIG. 4 according to the program stored in the ROM. This process starts when the reader / writer is turned on by turning on a power switch (not shown).

  First, the control unit 12 acquires the transmission unit initial voltage Mt0 and the APC target value Nt0 corresponding to the reference temperature t0 set in advance as ST (step) 1 from the setting table 30. As the reference temperature t0, a desired value of the measured temperature T set in the setting table 30, for example, t0 = 20 ° C., is preset on the nonvolatile memory 20.

  If the transmitter initial voltage Mt0 and the APC target value Nt0 at the reference temperature t0 are acquired from the setting table 30, the control unit 12 sets the transmitter initial voltage Mt0 acquired as ST2 in the transmitter initial voltage A area of the work area. To do. Similarly, the acquired APC target value Nt0 is set in the APC target value B area of the work area.

  In this state, the control unit 12 waits for an instruction to start communication with the data carrier as ST3. When receiving a read command or a write command for the data carrier from the host device, the control unit 12 determines that the start of communication with the data carrier has been commanded. And the control part 12 acquires the internal temperature t of the transmission / reception control apparatus 1 detected by the thermistor 17 as digital data as ST4.

  If the internal temperature t is acquired, the control part 12 will select the measurement temperature Tt with which the internal temperature t is the nearest among the measurement temperatures T set to the setting table 30 as ST5. At this time, when the internal temperature t is intermediate between two adjacent measured temperatures Tt1 and Tt2 (Tt1 <Tt2), the lower measured temperature Tt1 is selected. At this time, the higher measured temperature Tt2 may be selected.

  If the measured temperature Tt is selected, the control unit 12 determines whether or not the measured temperature Tt is equal to the reference temperature t0 in ST6. If they are equal, the processing of the next ST7 to ST9 is omitted.

  On the other hand, if they are not equal, the control unit 12 acquires the transmission unit initial voltage Mt and the APC target value Nt corresponding to the measured temperature Tt from the setting table 30 as ST7. If the transmission unit initial voltage Mt and the APC target value Nt are acquired, the control unit 12 obtains the correction value ΔM of the transmission unit initial voltage Mt and the correction value ΔN of the APC target value Nt as ST8 by the following equation (1), Calculate by (2). In equation (1), Mt0 is stored in the transmitter initial voltage A area of the work area. In the equation (2), Nt0 is stored in the APC target value B area of the work area.

ΔM = Mt−Mt0 (1)
ΔN = Nt−Nt0 (2)
After calculating the correction values ΔM and ΔN, the control unit 12 adds the correction value ΔM of the transmission unit initial voltage Mt to the transmission unit initial voltage A area of the work area (voltage initial value determination means) in ST9. Further, the correction value ΔN of the APC target value Nt is added to the APC target value B area of the work area.

  After correcting the transmitter initial voltage A and the APC target value B in ST9, or after determining that the measured temperature Tt is equal to the reference temperature t0 in ST6, the control unit 12 starts from the voltage adjustment circuit 19 as ST10. The voltage adjustment data A is output to the voltage adjustment circuit 19 so that the voltage supplied to the amplifier 133 of the transmission unit 13 becomes the value of the transmission unit initial voltage A area. Then, the output voltage value X (mV) given from the APC circuit 16 is acquired as ST11. This voltage value X (mV) is obtained by converting the power level of the transmission signal output from the transmission unit 13 to the antenna 2 into a voltage value by the APC circuit 16.

  In ST12, the control unit 12 determines whether or not the output voltage value X (mV) matches the APC target value B stored in the APC target value B area. If they do not match, the voltage adjustment data A to the voltage adjustment circuit 19 is increased or decreased by a predetermined value d (mV) as ST13. That is, when the output voltage value X is lower than the APC target value B, it is increased by a predetermined value d (mV), and when it is higher, it is decreased by a predetermined value d (mV). Then, returning to ST11, the output voltage value X (mV) from the APC circuit 16 is acquired again, and it is determined whether or not it matches the APC target value B. If not, the voltage adjustment data A is further set to a predetermined value. Increase / decrease by d (mV).

  Until the output voltage value X (mV) matches the APC target value B, the processing loop of ST11, ST12, ST13 is repeated. If they match, the control unit 12 executes a read / write process on the data carrier in ST14.

  Now, it is assumed that the values shown in FIG. This value has the characteristic that the circuit components constituting the transmitter 13 can obtain the target output power with a small voltage when the ambient temperature is low, but the voltage must be increased as the temperature rises. Means. Further, even when the circuit components constituting the APC circuit 16 detect the same power level, this means that the output voltage decreases as the ambient temperature increases.

  When the power of the reader / writer is turned on, the transmission / reception control device 1 first sets the transmitter initial voltage Mt0 and the APC target value Nt0 corresponding to the reference temperature t0 to the transmitter initial voltage A area and APC target value B area of the work area. Set to For example, if the reference temperature t0 is 20 ° C., 200 (mV) is set as the transmitter initial voltage Mt0 in the transmitter initial voltage A area, and 80 (mV) is set as the APC target value Nt0 in the APC target value B area. Set.

  Next, when a read command or a write command is given from the host device to the transmission / reception control device 1, the transmission / reception control device 1 detects the internal temperature t measured by the thermistor 17. For example, assume that the internal temperature t is 11 ° C. In this case, the transmission / reception control device 1 selects 10 ° C. as the measured temperature T closest to the internal temperature t. Then, the transmitter initial voltage 130 (mV) and the APC target value 90 (mV) corresponding to the measured temperature 10 ° C. are extracted from the setting table 30, and the transmitter initial voltage A and the APC target value B area in the transmitter initial voltage A area are extracted. The APC target value is corrected. That is, 130 (mV) is determined as the transmitter initial voltage, and 90 (mV) is determined as the APC target value.

  Thereafter, in the transmission / reception control device 1, the initial voltage 130 (mV) is supplied from the voltage adjustment circuit 19 to the amplifier 133 of the transmission unit 13 under the control of the control unit 12. Then, the power level of the transmission signal output from the transmission unit 13 to the antenna 2 is detected by the APC circuit 16, converted into an output voltage value X (mV), and supplied to the control unit 12. The control unit 12 compares the output voltage value X (mV) with the APC target value 90 (mV), and adjusts the voltage supplied from the voltage adjustment circuit 19 to the amplifier 133 according to the deviation. As a result, if the output voltage value X (mV) matches the APC target value 90 (mV), read / write processing for the data carrier is executed.

  Thus, in the present embodiment, at the start of communication with the data carrier, the internal temperature t in the transmission / reception control device 1 is measured, and the transmitter initial voltage is determined based on the internal temperature t. The transmitter initial voltage determined at this time is a voltage value when the power level of the transmission signal from the transmitter 13 becomes the target value when the temperature of the transmitter 13 is close to the internal temperature t. It is set in advance. Therefore, since the power level of the transmission signal is the target value itself or a value very close to the target value from the beginning of communication, the internal temperature t at the start of communication is the measured temperature set in the setting table 30 stepwise. Within the range, the time required for the power level to reach the target value can be reliably shortened regardless of the temperature characteristics of the transmitter 13. As a result, since the time required from the reception of the read command or the write command to the execution of the read / write process is shortened, the communication efficiency can be improved.

  In the present embodiment, at the start of communication with the data carrier, the internal temperature t in the transmission / reception control apparatus 1 is measured, and the APC target value is also determined based on the internal temperature t. The APC target value determined at this time is an output voltage value from the APC circuit 16 when the power level of the transmission signal from the transmission unit 13 becomes the target value in a state where the temperature of the transmission unit 13 is close to the internal temperature t. Yes, it is set in the setting table 30 in advance. Therefore, whether or not the power level of the transmission signal has reached the target value regardless of the temperature characteristics of the APC circuit 16 within the range of the measured temperature where the internal temperature t at the start of communication is set stepwise in the setting table 30. Can be accurately determined. As a result, the reliability as a reader / writer can be further enhanced.

  By the way, in the present embodiment, even during the execution of the read / write processing, the control unit 12 acquires the internal temperature t detected by the thermistor 17 at any time, and each time the measured temperature Tt with the closest internal temperature t is obtained. To decide. If the measured temperature Tt has changed since the previous determination, the control unit 12 acquires the APC target value Nt corresponding to the changed measured temperature Tt from the setting table 30, and the APC target value B is the value Nt. Thus, the value of the APC target value B area is corrected (output adjustment means).

  Normally, when the read / write process is executed, the internal temperature t of the transmission / reception control device 1 rises due to heat radiation from each circuit component. In the present embodiment, as the internal temperature t rises, the APC target value B is corrected to an optimum value so that the power level of the transmission signal output from the transmission unit 13 to the antenna 2 is always constant. I have control. Therefore, it is possible to always perform stable data communication with the data carrier regardless of changes in the internal temperature of the transmission / reception control device 1.

(Second Embodiment)
This embodiment is different from the first embodiment in a part of the reader / writer process executed by the control unit 12, and the processing procedure is shown in the flowchart of FIG.

  That is, in the present embodiment, when the reader / writer is powered on, the control unit 12 waits for a command to start communication with the data carrier as ST21. When receiving a read command or a write command for the data carrier from the host device, the control unit 12 determines that the start of communication with the data carrier has been commanded. And the control part 12 acquires the internal temperature t of the transmission / reception control apparatus 1 detected by the thermistor 17 as ST22 as digital data.

  If the internal temperature t is acquired, the control part 12 will select the measurement temperature Tt with which internal temperature t is the nearest among the measurement temperatures T set to the setting table 30 as ST23. At this time, when the internal temperature t is intermediate between two adjacent measured temperatures Tt1 and Tt2 (Tt1 <Tt2), the lower measured temperature Tt1 is selected. At this time, the higher measured temperature Tt2 may be selected.

  If the measured temperature Tt is selected, the control unit 12 acquires the transmission unit initial voltage Mt and the APC target value Nt corresponding to the measured temperature Tt from the setting table 30 in ST24. If the transmitter initial voltage Mt and the APC target value Nt are acquired, the control unit 12 sets the transmitter initial voltage Mt acquired as ST25 in the transmitter initial voltage A area of the work area. Similarly, the acquired APC target value Nt is set in the APC target value B area of the work area.

  Thereafter, the control unit 12 performs the same processing as ST10 to ST14 of the first embodiment as ST25 to ST30.

  Also in the second embodiment having such a configuration, at the start of communication with the data carrier, the internal temperature t in the transmission / reception control device 1 is measured, and the optimum transmitter initial voltage and APC correction value are determined based on the internal temperature t. Thus, the same effect as that of the first embodiment can be obtained. In addition, as compared with the first embodiment, the processing (ST1, ST2) for setting the values corresponding to the reference temperature t0 as defaults as the transmitter initial voltage and the APC target value can be omitted. Since the process of determining whether the temperature Tt matches the reference temperature t0 (ST6) can also be omitted, the number of processing steps of the control unit 12 can be reduced. As a result, communication efficiency can be increased.

(Third embodiment)
The difference between this embodiment and the first and second embodiments is also a part of the reader / writer process executed by the control unit 12, and the processing procedure is shown in the flowchart of FIG.

  That is, in this embodiment, when the reader / writer is powered on, the control unit 12 acquires the internal temperature t of the transmission / reception control device 1 detected by the thermistor 17 as ST31 as digital data. If the internal temperature t is acquired, the control part 12 will select the measurement temperature Tt with which the internal temperature t is the nearest among the measurement temperatures T set to the setting table 30 as ST32. At this time, when the internal temperature t is intermediate between two adjacent measured temperatures Tt1 and Tt2 (Tt1 <Tt2), the lower measured temperature Tt1 is selected. At this time, the higher measured temperature Tt2 may be selected.

  If the measured temperature Tt is selected, the control unit 12 acquires the transmission unit initial voltage Mt and the APC target value Nt corresponding to the measured temperature Tt from the setting table 30 as ST33. If the transmitter initial voltage Mt and the APC target value Nt are acquired, the control unit 12 sets the transmitter initial voltage Mt acquired as ST34 in the transmitter initial voltage A area of the work area. Similarly, the acquired APC target value Nt is set in the APC target value B area of the work area.

  Thereafter, the control unit 12 waits for an instruction to start communication with the data carrier in ST35. When receiving a read command or a write command for the data carrier from the host device, the control unit 12 determines that the start of communication with the data carrier has been commanded. And the control part 12 performs the process same as the process of ST10-ST14 of 1st Embodiment as ST36-ST40.

  In the third embodiment having such a configuration, when the reader / writer is turned on, the internal temperature t in the transmission / reception control device 1 is measured, and the optimum transmitter initial voltage and APC correction value are determined based on the internal temperature t. Is determined. Therefore, in a use environment where the interval from power-on to transmission start is short, the same effects as those of the first and second embodiments can be obtained. That is, it is possible to always perform stable data communication with the data carrier regardless of changes in the internal temperature of the transmission / reception control device 1. Moreover, communication efficiency can be improved.

  Note that the present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the constituent elements without departing from the spirit of the invention in the implementation stage.

  For example, in the embodiment, the interval of the measured temperature T set in the setting table 30 which is an example of the storage unit is 5 ° C., but the interval is not limited to 5 ° C. Further, the region of the measured temperature T is not limited to 0 ° C to 45 ° C. These temperature setting values can be appropriately set according to the usage environment of the reader / writer.

  The present invention is not limited to a reader / writer that performs wireless communication without contact with a data carrier, but can be applied to all wireless communication devices that include an APC circuit and perform wireless communication with a communication target.

In addition, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, the constituent elements over different embodiments may be combined.
Hereinafter, the invention described in the scope of claims of the present application will be appended.
[Appendix 1]
A transmission unit that modulates and amplifies a local signal and outputs a transmission signal to the antenna, and detects the power level of the transmission signal output from the transmission unit to the antenna so that the power level becomes a target value In a wireless communication apparatus comprising: an output adjustment unit that adjusts an amplification factor of the transmission unit by varying a voltage supplied to the transmission unit.
Temperature measuring means for measuring the temperature of the transmitter;
A voltage initial value determining means for determining an initial value of a voltage supplied to the transmitter according to a temperature measured by the temperature measuring means;
A wireless communication apparatus comprising:
[Appendix 2]
The voltage initial value determining means acquires the temperature measured by the temperature measuring means when receiving a communication start command, and determines the initial value of the voltage supplied to the transmitter according to the acquired temperature. The wireless communication device according to Supplementary Note 1, wherein the wireless communication device is characterized in that
[Appendix 3]
The voltage initial value determining means acquires a temperature measured by the temperature measuring means when the apparatus is turned on, and determines an initial value of a voltage supplied to the transmitter according to the acquired temperature. The wireless communication apparatus according to Supplementary Note 1.
[Appendix 4]
Corresponding to each of a plurality of stages of temperature data, power supply voltage data to the transmission unit when the target value is obtained as the power level of the transmission signal when the temperature of the transmission unit is the value of the corresponding data in advance Storage means for storing,
The voltage initial value determining means searches the storage means with the temperature measured by the temperature measuring means, and sets the supply voltage data corresponding to the temperature as the initial value of the voltage supplied to the transmitter. 4. The wireless communication device according to any one of supplementary notes 1 to 3, which is a feature.

FIG. 2 is a block diagram illustrating a main configuration of a reader / writer according to an embodiment of the present invention. The figure which shows the data structure example of the setting table memorize | stored in the non-volatile memory of the reader / writer. The figure which shows the main work areas which the control part of the reader / writer has. 6 is a flowchart showing a first embodiment of read / write processing executed by the control unit of the reader / writer. 9 is a flowchart showing a second embodiment of a read / write process executed by the control unit of the reader / writer. 12 is a flowchart showing a third embodiment of read / write processing executed by the control unit of the reader / writer.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Transmission / reception control apparatus, 2 ... Antenna, 11 ... Interface part, 12 ... Control part, 13 ... Transmission part, 14 ... Reception part, 15 ... Circulator, 16 ... APC circuit, 17 ... Thermistor, 18 ... A / D converter, DESCRIPTION OF SYMBOLS 19 ... Voltage adjustment circuit, 20 ... Non-volatile memory, 30 ... Setting table.

Claims (2)

A transmission unit that modulates and amplifies a local signal and outputs a transmission signal to the antenna, and detects the power level of the transmission signal output from the transmission unit to the antenna so that the power level becomes a target value In a data carrier reader / writer comprising output adjusting means for adjusting the amplification factor of the transmission unit by varying the voltage supplied to the transmission unit.
Temperature measuring means for measuring the temperature of the transmitter;
Corresponding to each of a plurality of stages of temperature data, power supply voltage data to the transmission unit when the target value is obtained as the power level of the transmission signal when the temperature of the transmission unit is the value of the corresponding data in advance Storage means for storing;
Upon reception of a read command or a write command for the data carrier, the temperature measured by the temperature measuring unit is acquired, the storage unit is searched with the acquired temperature, and the supply voltage data corresponding to the temperature is transmitted. Voltage initial value determining means for determining the initial value of the voltage supplied to the unit;
Control means for executing writing or reading of data to or from the data carrier at a voltage of an initial value determined by the voltage initial value determining means;
A data carrier reader / writer . Reference storage means for storing an initial voltage of the transmission unit corresponding to a reference temperature before receiving a read command or a write command for the data carrier;
Determining means for determining whether or not the temperature measured by the temperature measuring means is equal to the reference temperature;
When the determination unit determines that the temperature measured by the temperature measurement unit is equal to the reference temperature, the control unit writes or reads data to or from the data carrier with the initial voltage stored in the reference storage unit data of claim 1, wherein the performing a write or read of data to the data carrier with a voltage of the initial value determined by the voltage initial value determining means when the run was not equal Carrier leader / writer .

Images