JP5585244B2 - Portable wireless communication terminal - Google Patents

Description

  The present invention relates to a portable wireless communication terminal.

  At present, various wireless tag systems for reading wireless tags with portable wireless communication terminals are provided, and the applications of portable wireless communication terminals are widespread. In this portable wireless communication terminal, there is a case where it is required to appropriately adjust the output level of radio waves according to the environment. For example, Patent Document 1 provides a technique that enables such adjustment. Has been.

JP 2004-355212 A

  However, in the technique of Patent Document 1, it is necessary to add various hardware such as an antenna adjustment circuit, a power amplifier adjustment circuit, and a duty adjustment circuit as a circuit for controlling the radio wave output from the antenna. There are problems such as an increase in power consumption due to an increase in the size of the apparatus configuration or addition of hardware. In addition to this configuration, for example, a method of adjusting the radio wave output from the antenna by hardware, such as a configuration in which a variable attenuator or a variable gain amplifier is added, can be considered, but in any case, the above problem cannot be avoided.

  The present invention has been made to solve the above-described problems, and has a configuration capable of adjusting the radio wave output radiated from the antenna while suppressing an increase in the number of components, an increase in the size of the device configuration, and an increase in power consumption. It aims to be realized.

The invention according to claim 1 includes at least data processing means for generating transmission data to be transmitted to the wireless tag;
Signal output means for generating and outputting a baseband signal based on the transmission data generated by the data processing means;
Carrier generation means for generating a carrier;
A modulator that modulates the carrier wave generated by the carrier wave generating means based on the baseband signal output by the signal output means;
An antenna for transmitting radio waves according to the modulated signal generated by the modulator;
A portable wireless communication terminal equipped with
An output having voltage adjusting means capable of changing an offset voltage of the baseband signal output by the signal output means, and amplitude adjusting means capable of changing the amplitude of the baseband signal output by the signal output means. Control means ;
Monitoring signal output means for periodically outputting a monitoring signal;
Response wave detection means for detecting the presence or absence of a response wave output from the wireless tag according to the monitoring signal, and the amplitude of the response wave;
With
The output control means adjusts the offset voltage of the baseband signal by the voltage adjusting means according to the amplitude of the response wave detected by the response wave detecting means, and the baseband signal by the amplitude adjusting means. The output of the radio wave from the antenna is increased or decreased by adjusting the amplitude of.

  According to a second aspect of the present invention, in the portable wireless communication terminal according to the first aspect, each voltage candidate value used for setting the offset voltage and each amplitude candidate value used for setting the amplitude of the baseband signal are stored. The voltage adjustment means sets the offset voltage based on the voltage candidate value stored in the memory, and the amplitude adjustment means sets the amplitude candidate value stored in the memory to the amplitude candidate value. Based on this, the amplitude of the baseband signal is set.

The invention of claim 3 further includes mode switching means capable of switching the power consumption mode of the portable wireless communication terminal between a predetermined normal mode and a power saving mode that suppresses power consumption more than the normal mode. The response wave detection unit is configured to detect the presence or absence of the response wave from the wireless tag with respect to the monitoring signal, and the mode switching unit consumes the response wave when the response wave is not detected by the response wave detection unit. The power mode is switched to the power saving mode.

According to a fourth aspect of the invention, the data processing means is capable of transmitting a read command for reading the wireless tag, and writing capable of transmitting a write command for writing data to the wireless tag. A distance calculating unit that calculates a distance from the portable wireless communication terminal to the wireless tag based on an amplitude of the response wave from the wireless tag with respect to the monitoring signal. And the output control means increases or decreases the output from the antenna according to the distance calculated by the distance calculation means, and at the time of reading processing by the reading processing means at the calculated distance. The output from the antenna is set so that the output at the time of the writing process by the writing processing means is larger than the output of To have.

According to the first aspect of the present invention, there is provided voltage adjusting means capable of changing the offset voltage of the baseband signal output by the signal output means, and amplitude adjusting means capable of changing the amplitude of the baseband signal output by the signal output means. Output control means, and the output control means adjusts the offset voltage of the baseband signal by the voltage adjustment means, and adjusts the amplitude of the baseband signal by the amplitude adjustment means, thereby outputting the radio wave from the antenna. It is changing. According to this configuration, since the radio wave output radiated from the antenna can be changed by adjusting the offset voltage and amplitude of the baseband signal input to the modulator, other hardware for changing the radio wave output is provided. Wear can be suppressed or reduced. Therefore, a configuration capable of changing the radio wave output from the antenna can be realized while suppressing an increase in the number of parts, an increase in the size of the device configuration, and an increase in power consumption.
In addition, a monitoring signal output unit that periodically outputs a monitoring signal, and a response wave detection unit that detects the presence / absence of a response wave output from the wireless tag according to the monitoring signal and the amplitude of the response wave are provided. . According to this configuration, the wireless tag can be periodically monitored, and the monitoring result (the presence or absence of a response wave or the amplitude of the response wave) can be used.
Further, the response wave detecting means is configured to detect at least the amplitude of the response wave from the wireless tag with respect to the monitoring signal, and the output control means outputs from the antenna in accordance with the amplitude of the response wave detected by the response wave detecting means. The output is increased or decreased. In this configuration, by detecting the amplitude of the response wave from the wireless tag, the distance to the wireless tag can be estimated, and the output of the radio wave from the antenna is set to an appropriate level according to the distance to the wireless tag. Easy to set.

  The invention of claim 2 has a memory capable of storing each voltage candidate value used for setting the offset voltage and each amplitude candidate value used for setting the amplitude of the baseband signal, and the voltage adjusting means stores it in the memory. The offset voltage is set based on the voltage candidate value to be set, and the amplitude adjusting means sets the amplitude of the baseband signal based on the amplitude candidate value stored in the memory. In this configuration, if the offset voltage and amplitude value to be used are stored in the memory in advance, the offset voltage and amplitude of the baseband signal are immediately set to the values stored in the memory during actual use. Therefore, the radio wave output adjustment operation can be speeded up and facilitated.

The invention according to claim 3 is provided with mode switching means capable of switching the power consumption mode of the portable wireless communication terminal between a predetermined normal mode and a power saving mode in which power consumption is suppressed compared to the normal mode. The response wave detection unit is configured to detect the presence or absence of a response wave from the wireless tag with respect to the monitoring signal, and the mode switching unit saves the power consumption mode when the response wave is not detected by the response wave detection unit. Switching to power mode. According to this configuration, power consumption can be effectively suppressed in a situation where there is no wireless tag within the communication range of the portable wireless communication terminal and communication processing is not performed with the wireless tag.

According to a fourth aspect of the present invention, the data processing means includes a reading processing means capable of transmitting a reading command for reading the wireless tag, and a writing processing means capable of transmitting a writing command for writing data to the wireless tag. It has. The response wave detection means includes distance calculation means for calculating the distance from the portable wireless communication terminal to the wireless tag based on the amplitude of the response wave from the wireless tag with respect to the monitoring signal. The output from the antenna is increased / decreased according to the distance calculated by the calculation means, and at the calculated distance, the output at the time of the writing processing by the writing processing means is more than the output at the time of the reading processing by the reading processing means. The output from the antenna is set to increase. According to this configuration, it is possible to stably ensure an appropriate output according to the distance at the time of writing that requires a larger output than at the time of reading.

FIG. 1 is a block diagram schematically illustrating an electrical configuration of the portable wireless communication terminal according to the first embodiment of the present invention. FIG. 2 is a block diagram illustrating an electrical configuration of a wireless tag read by the portable wireless communication terminal of FIG. 3A is a graph for explaining the relationship between voltage and time for a baseband signal, and FIG. 3B is a relationship between output power and time for a modulated signal output from the modulator. It is a graph explaining. FIG. 4 is an explanatory diagram illustrating an example in which the center power and the amplitude of the output power from the modulator are changed by adjusting the offset voltage and the amplitude of the baseband signal. FIG. 5 is a graph showing the relationship between the input voltage input to the modulator and the output power. 6A is an explanatory diagram for explaining an example of storing a plurality of combinations of offset voltage and amplitude, and FIG. 6B is an example in which the output level from the antenna is set to a level corresponding to the amplitude of the response wave. It is explanatory drawing explaining these.

[First embodiment]
Hereinafter, a first embodiment of a portable wireless communication terminal according to the present invention will be described with reference to the drawings.
(Overall configuration of portable wireless communication terminal)
First, the overall configuration of the portable wireless communication terminal 1 according to the first embodiment will be outlined with reference to FIG. 1, and the configuration of the wireless tag will be described. FIG. 1 is a block diagram schematically illustrating an electrical configuration of the portable wireless communication terminal according to the first embodiment of the present invention. FIG. 2 is a block diagram illustrating an electrical configuration of a wireless tag read by the portable wireless communication terminal of FIG.

  As shown in FIG. 1, the portable wireless communication terminal 1 is configured as a known RFID reader / writer in hardware, for example, to read data recorded in a wireless tag 50 described later, or to the wireless tag 50. It is configured to write data. The portable wireless communication terminal 1 is mainly configured by a control unit 10, a transmission circuit 20, a reception circuit 30, an antenna 40, a circulator 41, and the like.

  The control unit 10 governs overall control of the portable wireless communication terminal 1 and is configured by a control circuit such as an FPGA or a CPU. The control unit 10 is also provided with a transmission data generation unit 11 that provides transmission data to the transmission circuit 20, a decoding processing unit 12 that acquires and decodes binarized data from the reception circuit 30, and the like.

  The transmission circuit 20 includes a frequency synthesizer 21, a D / A converter 22, a baseband filter 23, a modulator 24, an RF band filter 25, a power amplifier 26, and the like.

  The frequency synthesizer 21 corresponds to an example of “carrier generation means”, and has a configuration in which a carrier (carrier wave) having a predetermined frequency is output. The D / A converter 22 generates a baseband signal by converting transmission data (digital signal) generated by the transmission data generation unit 11 of the control unit 10 into an analog signal. The baseband filter 23 is configured as a band limiting filter (analog filter) for limiting to a predetermined baseband band, and out of the predetermined baseband band among the signals output from the D / A converter 22 The signal part is limited.

  The modulator 24 modulates the baseband signal output from the baseband filter 23 with the oscillation signal from the frequency synthesizer 21 and converts it into a modulated signal (RF signal). The RF band filter 25 is configured as a band limiting filter that limits the band of the signal output from the modulator 24 to a predetermined RF band, and the signal output from the modulator 24 is out of the predetermined RF band. The signal part is limited.

  The power amplifier 26 amplifies the input signal (the modulated signal modulated by the modulator 24 and output from the RF band filter 25) with a predetermined gain. An RF band signal output from the power amplifier 26 is output as a transmission radio wave via the circulator 41 and the antenna 40.

  On the other hand, the receiving circuit 30 includes an RF band filter 31, a demodulator 33, baseband band filters 34a and 34b, A / D converters 35a and 35b, and the like.

  The RF band filter 31 is configured as a band limiting filter for limiting to a predetermined RF band, and limits a signal portion outside the predetermined RF band in the received signal input via the antenna 40 and the circulator 41. ing. Further, the demodulator 33 is configured as a quadrature demodulator, for example, and outputs an in-phase component and a quadrature component based on an unmodulated carrier wave (reference signal) distributed from the frequency synthesizer 21 to the signal output from the RF band filter 31. It is extracted and converted into amplitude information and phase information.

  Each of the baseband filters 34a and 34b is configured as a band limiting filter that limits the band of a predetermined baseband signal, and for each of the in-phase component signal and the quadrature component signal converted by the demodulator 33. Thus, the signal portion outside the predetermined baseband is limited. The outputs from the baseband filters 34a and 34b are converted into digital signals by the A / D converters 35a and 35b, respectively, and input to the decoding processing unit 12.

  The control unit 10 is also connected to a display unit 14 (see FIG. 3) including an input key and a liquid crystal display (not shown). Furthermore, a memory 13 made of a semiconductor memory such as a ROM, a RAM, a nonvolatile memory, or the like is connected to the control unit 10 so that various types of information can be stored.

The wireless tag 50 read by the portable wireless communication terminal 1 is configured, for example, as shown in FIG.
The wireless tag 50 is configured as a known RFID tag in hardware, for example, and includes an antenna 51, a power supply circuit 52, a demodulation circuit 53, a control circuit 54, a memory 55, a modulation circuit 56, and the like as shown in FIG. It is configured. The power supply circuit 52 rectifies and smoothes a transmission signal (carrier signal) received from the portable wireless communication terminal 1 via the antenna 51 to generate an operation power supply. The operation power supply is used as a control circuit. It supplies to each component including 54.

  The demodulating circuit 53 demodulates the data superimposed on the transmission signal (carrier signal) and outputs it to the control circuit 54. The memory 55 includes various semiconductor memories such as a ROM and an EEPROM, and includes tag identification information (tag ID) for identifying the control program, the wireless tag 50, and data set by the user according to the use of the wireless tag 50. (Product data, logistics data, etc.) are stored. The control circuit 54 is configured to read the information and data from the memory 55 and output it as transmission data to the modulation circuit 56. The modulation circuit 56 performs load modulation on the carrier signal with the transmission data and performs the antenna 51. Is transmitted as a reflected wave.

(Detailed description of characteristic parts)
3A is a graph for explaining the relationship between voltage and time for a baseband signal, and FIG. 3B is a relationship between output power and time for a modulated signal output from the modulator. It is a graph explaining. FIG. 4 is an explanatory diagram illustrating an example in which the center power and the amplitude of the output power from the modulator are changed by adjusting the offset voltage and the amplitude of the baseband signal. FIG. 5 is a graph showing the relationship between the input voltage input to the modulator and the output power. FIG. 6A is an explanatory diagram illustrating an example of storing a plurality of combinations of offset voltage and amplitude.

  As described above, the portable wireless communication terminal 1 according to the present embodiment generates data (transmission data) to be transmitted to the wireless tag 50 by the transmission data generation unit 11 of the control unit 10. The transmission data generated by the control unit 10 is a baseband signal, and the voltage value at each time is represented by digital data. The transmission data generator 11 raises the output level so that the center voltage of the baseband signal becomes a preset offset voltage Vb, for example, as conceptually shown in FIG. A voltage value (digital value) for each time is generated and output so as to have a preset amplitude Ab, and the baseband signal (digital signal) generated and output by the transmission data generation unit 11 in this way. Are converted into analog signals by the A / D converter 22.

  In the present embodiment, the control unit 10 corresponds to an example of a “data processing unit”. It functions to generate transmission data to be transmitted to at least the wireless tag 50. The control unit 10 and the A / D converter 22 correspond to an example of “signal output unit”, and function to generate and output a baseband signal based on transmission data generated by the “data processing unit”. .

  The baseband signal generated as a digital signal by the control unit 10 and converted into an analog signal by the D / A converter 22 is filtered by the baseband filter 23 and then input to the modulator 24. The modulator 24 modulates the carrier wave generated by the frequency synthesizer 21 based on the baseband signal (hereinafter also referred to as a BB signal) input in this way, for example, by the ASK modulation method, and generates a modulated signal in the RF band. doing.

  In the modulated signal generated by the modulator 24, the center power Pr of the output power becomes a level corresponding to the offset voltage Vb of the baseband signal, and the maximum amplitude Ar of the output power is a level corresponding to the maximum amplitude Ab of the baseband signal. It has become. In FIG. 4, the modulated signal when the baseband signal is Sb1 is indicated by Sr1, and the modulated signal when the baseband signal is Sb2 is indicated by Sr2. Further, the modulated signal when the baseband signal is Sb3 is indicated by Sr3. As shown in FIG. 4, in the modulated signal output from the modulator 24, the center power Pr of the modulated signal increases as the offset voltage Vb of the baseband signal increases, and the maximum amplitude Ab of the baseband signal increases. As the modulated signal is generated, the maximum amplitude Ar is increased.

  The RF-band modulated signal generated in this way is filtered by the RF band filter 25 and then amplified by the gain set in the power amplifier 26, and is generated from the antenna 40 by the modulator 24. A radio wave corresponding to the modulated signal (that is, a radio wave having an output level corresponding to the offset voltage Vb and amplitude Ab of the baseband signal) is transmitted.

In the present embodiment, the control unit 10 that generates the baseband signal corresponds to an example of a “voltage adjusting unit”, and is configured to be able to change the setting of the offset voltage Vb of the baseband signal. The control unit 10 corresponds to an example of an “amplitude adjusting unit” and is configured to be able to change the setting of the maximum amplitude Ab of the baseband signal. The control unit 10 corresponds to an example of “output control means”.
It functions to change the output of the radio wave from the antenna 40 by adjusting the offset voltage Vb of the baseband signal and adjusting the amplitude Ab of the baseband signal.

  The modulator 24 used in the present embodiment has an input voltage-output power characteristic as shown in FIG. 5, for example. When the baseband signal is Sb1, the input voltage range is D1, The range of the output power of the modulated signal Sr1 is P1. Further, when the baseband signal is Sb2, the input voltage range is D2, the output power range of the modulated signal Sr2 is P2, and when the baseband signal is Sb3, the input voltage range is D3, The range of the output power of the modulated signal Sr3 is P3. In this configuration, the output change ranges of the modulated signals Sr1, Sr2, and Sr3 generated by the baseband signals Sb1, Sb2, and Sb3 are in the range of about 20 dB (the range of about −13 dBm to about 7 dBm), while the modulator 24 In this characteristic, the range in which the output power can be changed is about 50 dB (a range of about −42 dBm to about 8 dBm), so a characteristic margin of about 30 dB is generated. Therefore, the offset voltage Vb and the amplitude Ab can be varied using the characteristic margin of about 30 dB.

  In the present embodiment, a plurality of combinations of the offset voltage Vb of the baseband signal and the maximum amplitude Ab are stored. Specifically, the memory 13 shown in FIG. 1 stores a plurality of settings for switching the output level to a plurality of stages as shown in FIG. 6A, and is used for setting the offset voltage Vb in each setting. Each voltage candidate value and each amplitude candidate value used for setting the maximum amplitude Ab of the baseband signal are stored in association with each other. For example, when setting 1 (output level 1) is set to increase the level of radio wave output from the antenna, the offset voltage is set to Vb1 which is the largest among the voltage candidate values, and the maximum amplitude is Ab1 which is the largest among the amplitude candidate values. Is set to. In addition, when the level of radio wave output from the antenna is set 2 (output level 2), which is slightly smaller than setting 1, the offset voltage is set to Vb2, which is slightly smaller than Vb1, and the maximum amplitude is slightly smaller than Ab1. It is set to Ab1. Similarly, in the case of setting 3 (output level 2) in which the level of radio wave output from the antenna is slightly smaller than setting 2, the offset voltage is set to Vb3 that is slightly smaller than Vb2, and the maximum amplitude is slightly smaller than Ab2. A small Ab3 is set. Since the setting contents are stored in this way, the magnitude of the radio wave output from the antenna 40 is smaller in the setting 2 than in the setting 1, and in the setting 3 than in the setting 2 However, the magnitude of the radio wave output from the antenna 40 is reduced.

  The transmission data generation unit 11 serves as a baseband signal reference by a known method based on data prepared for transmission to the wireless tag 50 by the control unit 10 (for example, data such as commands and written contents). A reference signal (a baseband signal whose offset voltage is a predetermined reference voltage and whose maximum amplitude is a predetermined reference amplitude) is generated. The offset voltage of the reference signal generated by referring to the setting designated by the user or one of the settings instructed by the control from among the plurality of setting contents (see FIG. 6) stored in the memory 13. Is raised from the level of the reference voltage to the offset voltage value specified by the setting. Further, the maximum amplitude of the reference signal is increased from a predetermined reference amplitude so as to become an amplitude value designated by the setting. As a result, a baseband signal having a desired offset voltage and maximum amplitude is generated.

(Main effects of the first embodiment)
In the portable wireless communication terminal 1 according to the present embodiment, the voltage adjustment unit capable of changing the offset voltage Vb of the baseband signal output by the signal output unit, and the amplitude Ab of the baseband signal output by the signal output unit. An output control means (control unit 10) having a variable amplitude adjustment means is provided. The voltage adjustment means adjusts the offset voltage Vb of the baseband signal, and the amplitude adjustment means adjusts the amplitude Ab of the baseband signal. By doing so, the output of the radio wave from the antenna 40 is changed.
According to this configuration, the radio wave output radiated from the antenna 40 can be changed by adjusting the offset voltage Vb and the amplitude Ab of the baseband signal input to the modulator 24, so that the radio wave output can be changed. Other hardware can be suppressed or reduced. Therefore, a configuration capable of changing the radio wave output from the antenna 40 can be realized while suppressing an increase in the number of parts, an increase in the size of the device configuration, and an increase in power consumption.

In the present embodiment, the memory 13 can store each voltage candidate value used for setting the offset voltage Vb and each amplitude candidate value used for setting the amplitude Ab of the baseband signal. Then, the voltage adjusting unit sets the offset voltage Vb based on the voltage candidate value stored in the memory 13, and the amplitude adjusting unit sets the amplitude Ab of the baseband signal based on the amplitude candidate value stored in the memory 13. It is set.
In this configuration, if the values of the offset voltage Vb and the amplitude Ab to be used are stored in the memory 13 in advance, the offset voltage Vb and the amplitude Ab of the baseband signal are stored in the memory 13 during actual use. The value can be set immediately, and radio wave output adjustment can be speeded up and facilitated.

[Second Embodiment]
Next, a first embodiment of the present invention will be described. The second embodiment has all the configurations and features of the first embodiment, and the following features are further added. Accordingly, detailed description of the same parts as those in the first embodiment will be omitted, and FIGS. 1 to 6 will be referred to as appropriate.

  In the present embodiment, in addition to the configuration of the above embodiment, a predetermined pilot signal (monitoring signal) is periodically output from the control unit 10 at a time when a carrier wave is output from the transmission circuit 20. Specifically, the control unit 10 periodically outputs a query signal including a predetermined inquiry command, and the query signal is radiated as a radio wave from the antenna 40. The portable wireless communication terminal 1 Only the wireless tag 50 that exists in a range in which communication with the wireless communication apparatus can receive the query signal. In the present embodiment, the control unit 10 corresponds to an example of a “monitoring signal output unit” and functions to periodically output a monitoring signal.

  The wireless tag 50 is configured to return a predetermined response signal determined in advance when receiving the query signal. Specifically, for example, the control circuit 54 of the wireless tag 50 determines whether or not the query signal is included in the received signal (the signal demodulated by the demodulation circuit 53), and the received signal includes the query signal. In some cases, a predetermined response signal determined in advance is output.

A response signal (a signal responding to the query signal) transmitted from the wireless tag 50 in this way is received by the receiving circuit 30, demodulated by the receiving circuit 30, and input to the control unit 10. On the other hand, after transmitting the query signal via the transmission circuit 20, the control unit 10 determines whether or not a predetermined response signal determined in advance has been received by the reception circuit 30 (that is, the predetermined response signal from the reception circuit 30). Whether or not a signal is input).
In the present embodiment, the receiving circuit 30 and the control unit 10 correspond to an example of “response wave detection means”, and detect the presence or absence of a response wave output from the wireless tag 50 in response to a query signal (monitoring signal). To function. And since it is comprised in this way, the radio | wireless tag 50 can be monitored regularly and the monitoring result (the presence or absence of a response wave) can be utilized for another process.

  The control unit 10 periodically outputs a query signal as described above, but reception of a response wave (response signal) in response to the query signal is not detected even after a predetermined time has elapsed after transmission of the query signal. Sometimes, the power consumption mode of the portable wireless communication terminal 1 is switched to the power saving mode.

  In the present embodiment, the control unit 10 corresponds to an example of a “mode switching unit”, and the power consumption mode of the portable wireless communication terminal 1 is set to a predetermined normal mode, and the power consumption is suppressed more than the normal mode. Functions to switch to the power mode, and functions to switch the power consumption mode to the power saving mode at least when the response wave (response signal responding to the query signal) is not detected by the “response wave detection means” doing.

  Note that the distinction between “normal mode” and “power saving mode” can be made variously. The state where the carrier wave (carrier) output is continued is the “normal mode” and the carrier wave output is interrupted. Can be set to “power saving mode”. In this case, for example, the query signal is periodically output while the carrier wave (carrier) is being output (that is, in the normal mode). When the response wave is not transmitted from the wireless tag 50, control to stop the output of the carrier wave and shift to the power saving mode (power saving control) is performed, and the response wave is transmitted from the wireless tag 50 for a predetermined time. In this case, control for maintaining the output of the carrier wave (control for maintaining the normal mode) can be performed. Further, when shifting to the power saving mode, after the output of the carrier wave is stopped, the output of the carrier wave is started based on establishment of a predetermined condition (for example, a predetermined operation by the user, detection of a reading target by an object detection sensor, etc.). Control can be performed.

  Further, the distinction between the “normal mode” and the “power saving mode” is not limited to such an example. For example, a mode in which the radio wave output from the antenna 40 is set to a predetermined high level state is set to “normal mode”, and the radio wave output from the antenna 40 is set to a predetermined low level state lower than that in the high level state. The mode to be performed may be a “power saving mode”. In this case, for example, the query signal is periodically output from the control unit 10 in the “normal mode” or the “power saving mode”, and the query signal thus output is output for a predetermined time. When a response wave is not transmitted from the wireless tag 50, control (power saving control) is performed so that the radio wave output from the antenna 40 is in the low level state, and the wireless tag is applied to the query signal for a predetermined time. When a response wave is transmitted from 50, it is possible to perform control such that the radio wave output from the antenna 40 is in the high level state. When the low level state is set, after the setting, a predetermined condition is satisfied (for example, detection of a response wave to the query signal, a predetermined operation by the user, detection of a reading target by an object detection sensor, etc.). Control can be performed again to return the radio wave output from the antenna 40 to the high level state.

  According to the configuration of the present embodiment, power consumption is effectively reduced in a situation where the wireless tag 50 does not exist within the communication range of the portable wireless communication terminal 1 and communication processing is not performed with the wireless tag 50. Can be suppressed.

[Other Embodiments]
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.

  In the second embodiment, the receiving circuit 30 and the control unit 10 corresponding to the “response wave detection means” detect the presence or absence of a response wave from the wireless tag 50 with respect to the query signal (monitoring signal). The “detecting means” may be configured to detect the amplitude of the response wave from the wireless tag 50 with respect to the query signal. Then, according to the amplitude of the response wave detected by the “response wave detection unit”, the above-mentioned “output control unit” (that is, the control unit 10) may increase or decrease the output from the antenna 40.

  Specifically, as shown in FIG. 6B, for example, the offset voltage Vb and the amplitude are set such that the output level from the antenna 40 increases as the degree of the amplitude of the response wave from the wireless tag 50 with respect to the query signal decreases. Ab can be switched. In the example of FIG. 6B, the output level of the radio wave radiated from the antenna 40 can be set in a plurality of stages. When the amplitude level of the response wave with respect to the query signal is less than the predetermined threshold A1, the antenna 40 Is set to the output level 1 (setting 1) at which the output from the output is maximized. At this time, the offset voltage Vb is set to Vb1 which is the maximum among the setting candidate values, and the amplitude Ab (maximum amplitude). ) Is set to Ab1 which is the maximum among the setting candidate values. Further, when the level of the amplitude of the response wave with respect to the query signal is not less than the threshold value A1 and less than A2, it is set to the output level 2 (setting 2) that suppresses the output from the antenna 40 rather than the output level 1 (setting 1). At this time, the offset voltage is set to Vb2 smaller than Vb1, and the amplitude (maximum amplitude) is set to Ab2 smaller than Ab1. In the table of FIG. 6B, A1 <A2 <A3 <A4 <A5. In this case, the setting of FIG. 6A is Vb1> Vb2> Vb3> Vb4> Vb5 and Ab1> Vb2 > Vb3> Vb4> Vb5.

  In this example, the control unit 10 corresponding to “distance calculation means” and “output control means” wirelessly transmits from the portable wireless communication terminal 1 based on the amplitude of the response wave from the wireless tag 50 to the query signal (monitoring signal). It functions to calculate the distance to the tag 50 and increase / decrease the output from the antenna according to the calculated distance. Note that the calculation method of the “distance” to the wireless tag 50 can be various. As shown in FIG. 6B, the amplitude of the response wave detected in response to the transmission of the query signal is set to the “distance”. The “distance” may be calculated by a predetermined arithmetic expression (for example, a proportional expression) using the response wave amplitude as a parameter. Alternatively, a table in which the amplitude of the response wave is associated with the distance value in advance may be prepared, and the distance may be calculated with reference to the table when the response wave amplitude is obtained. As described above, when the distance to the wireless tag 50 is calculated based on the amplitude of the response wave from the wireless tag 50 using an arithmetic expression or a table, the radio wave output from the antenna 40 increases as the calculated distance increases. As described above, the offset voltage Vb and the amplitude Ab can be switched continuously or stepwise.

  In the present embodiment, the control unit 10 corresponds to an example of “reading processing unit”, and is configured to be able to transmit a reading command for reading the wireless tag 50. The control unit 10 corresponds to an example of “write processing means” and is configured to be able to transmit a write command for writing data to the wireless tag 50. Then, at each distance, the output from the antenna 40 is set so that the output at the time of the writing process by the writing process unit is larger than the output at the time of the reading process by the reading process unit. For example, at the time of reading, the output level is set as shown in FIGS. 6A and 6B according to the amplitude of the response wave responded to the query signal as described above. It can be set so that at least one of the offset voltage and the maximum amplitude is increased by a predetermined percentage. For example, when the amplitude of the response wave with respect to the query signal is not less than A1 and less than A2, the output level is set to 2 (offset voltage Vb2 and amplitude Ab2) as shown in FIG. In the case of writing processing, an output level higher than this (for example, setting 1 of the offset voltage Vb1 and the amplitude Ab1) can be achieved.

  According to the above configuration, the distance to the wireless tag 50 can be estimated more appropriately by detecting the amplitude of the response wave from the wireless tag 50, and the output of the radio wave from the antenna 40 can be changed to the wireless tag 50. It becomes easy to set to an appropriate level according to the distance. In particular, it is possible to stably ensure an appropriate output corresponding to the distance at the time of writing that requires a larger output than at the time of reading.

DESCRIPTION OF SYMBOLS 1 ... Portable radio | wireless communication terminal 10 ... Control part (Data processing means, signal output means, output control means, voltage adjustment means, amplitude adjustment means, response wave detection means, mode switching means, reading processing means, writing processing means)
13 ... Memory 21 ... Frequency synthesizer (carrier generation means)
22 ... DA converter (signal output means)
24. Modulator 30. Receiving circuit (response wave detecting means)
40 ... Antenna

Claims (4)

Data processing means for generating transmission data to be transmitted to at least the wireless tag;
Signal output means for generating and outputting a baseband signal based on the transmission data generated by the data processing means;
Carrier generation means for generating a carrier;
A modulator that modulates the carrier wave generated by the carrier wave generating means based on the baseband signal output by the signal output means;
An antenna for transmitting radio waves according to the modulated signal generated by the modulator;
A portable wireless communication terminal equipped with
An output having voltage adjusting means capable of changing an offset voltage of the baseband signal output by the signal output means, and amplitude adjusting means capable of changing the amplitude of the baseband signal output by the signal output means. Control means ;
Monitoring signal output means for periodically outputting a monitoring signal;
Response wave detection means for detecting the presence or absence of a response wave output from the wireless tag according to the monitoring signal, and the amplitude of the response wave;
With
The output control means adjusts the offset voltage of the baseband signal by the voltage adjusting means according to the amplitude of the response wave detected by the response wave detecting means, and the baseband signal by the amplitude adjusting means. A portable wireless communication terminal characterized in that the output of the radio wave from the antenna is increased or decreased by adjusting the amplitude of the antenna. A memory capable of storing each voltage candidate value used for setting the offset voltage and each amplitude candidate value used for setting the amplitude of the baseband signal;
The voltage adjusting means sets the offset voltage based on the voltage candidate value stored in the memory,
The portable radio communication terminal according to claim 1, wherein the amplitude adjustment unit sets the amplitude of the baseband signal based on the amplitude candidate value stored in the memory. Comprising a mode switching means capable of switching the power consumption mode of the portable wireless communication terminal between a predetermined normal mode and a power saving mode that suppresses power consumption more than the normal mode;
The response wave detection means is configured to detect the presence or absence of the response wave from the wireless tag with respect to the monitoring signal,
3. The portable wireless communication according to claim 1, wherein the mode switching unit switches the power consumption mode to the power saving mode when the response wave is not detected by the response wave detection unit. Terminal. The data processing means includes reading processing means capable of transmitting a reading command for reading the wireless tag, and writing processing means capable of transmitting a writing command for writing data to the wireless tag,
The response wave detection means includes distance calculation means for calculating a distance from the portable wireless communication terminal to the wireless tag based on an amplitude of the response wave from the wireless tag with respect to the monitoring signal,
The output control means increases or decreases the output from the antenna according to the distance calculated by the distance calculation means, and at the calculated distance, the output from the reading processing means by the reading processing means The portable wireless communication terminal according to any one of claims 1 to 3 , wherein the output from the antenna is set so that the output during the writing process by the writing processing means is larger. .

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