JP2016192657A - Radio communication device and radio communication device control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio communication device and a radio communication device control method, which can suppress power consumption required for searching a connection destination in a resting state.SOLUTION: A printer 1 to which a radio communication device of the present embodiment is applied comprises: a communication part 110 for performing radio communication; a receiving signal strength measurement part 120 for measuring a change in strength of a signal received by the communication part 110; and a searching part 150 for searching a connection destination of the communication part 110. The searching part 150 sets a searching frequency at a first value when a change in received signal strengths measured by the receiving signal strength measurement part 120 is equal to or larger than a predetermined threshold value and sets a searching frequency at a second value lower than the first value when a change in the receiving signal strength is less than the predetermined threshold value.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a wireless communication device capable of varying a search frequency for searching for a connection destination and a method for controlling the wireless communication device.

  Conventionally, for example, Patent Document 1 is known as this type of technology. Patent Document 1 discloses a portable wireless communication device that determines that it is not suitable for communication because the time of staying in one zone is shortened when moving at high speed, and reduces the search frequency for searching for a connection destination. Yes. With this configuration, the wireless communication device can suppress unnecessary searching and can save power.

  On the other hand, variable control of search frequency is also performed in mobile printers equipped with this type of wireless communication device. In the case of a mobile printer, since it is used under the condition that the radio wave environment of the wireless LAN changes every moment due to transportation by the user, the search frequency is generally varied based on the received signal strength from the access point. In other words, the power consumption when the reception state is good is reduced by increasing the search frequency when the received signal strength is weak and decreasing the search frequency when the received signal strength is high.

JP 2008-66892 A

  However, since the conventional mobile printer as described above controls the search frequency based on the received signal strength, the search frequency is high when the received signal strength is low even if the radio wave environment is stationary and the radio wave environment is stable. As a result, power consumption increases. On the other hand, since the technique of Patent Document 1 suppresses a search during high-speed movement, it cannot be expected to have a power saving effect while stationary.

  In view of the above problems, an object of the present invention is to provide a wireless communication device and a wireless communication device control method capable of suppressing power consumption required for searching for a connection destination in a stationary state.

  A wireless communication device of the present invention includes a communication unit that performs wireless communication, a received signal strength measurement unit that measures a change in received signal strength of the communication unit, and a search unit that searches for a connection destination of the communication unit. The search frequency is set to the first value when the change in the received signal strength measured by the received signal strength measuring unit is greater than or equal to the predetermined threshold, and the search frequency is set to the first value when the change in the received signal strength is less than the predetermined threshold. The second value is lower than the value of.

  A method for controlling a wireless communication device of the present invention is a method for controlling a wireless communication device including a communication unit, and includes a received signal strength measuring step for measuring a change in received signal strength of the communication unit, and a connection destination of the communication unit. A search step for searching, and when the change in the received signal strength measured in the received signal strength measuring step is equal to or greater than a predetermined threshold, the search frequency is set to the first value and the change in the received signal strength is performed. Is less than the predetermined threshold, the search frequency is set to a second value lower than the first value.

According to the configuration of the present invention, when the change in the received signal strength is less than the predetermined threshold, that is, when the device main body is not moving, the radio frequency environment is stable in order to reduce the search frequency compared to when the device is moving. Therefore, unnecessary search in the case of being in the state can be suppressed, and thus a power saving effect can be expected.
The application of the present invention may cause a situation where the search frequency is low even when the received signal strength is weak. However, depending on the applied electronic device such as a mobile printer, the operation and / or results may be achieved even when the received signal strength is low. The application of the present invention is useful because it has little effect on objects.

  The wireless communication device further includes a printing unit, and the searching unit sets the search frequency to the second value when the printing unit is in an error state even when the change in received signal strength is equal to or greater than a predetermined threshold. Features.

According to the configuration of the present invention, when the printing unit is in an error state, it is meaningless to increase the search frequency. Therefore, unnecessary search can be suppressed and higher power saving effect can be expected.
Note that “when the printing unit is in an error state” means that there are printing-related abnormalities such as out of paper, paper jam, open cover of the roll paper container, out of ink / toner, paper cutter error, abnormal print head temperature, etc. Refers to the state that occurred.

  In the above wireless communication device, when the search unit changes the connection destination of the communication unit, the search frequency is not changed until a predetermined time elapses after the change.

  When the connection destination is changed, there is a possibility that the change in the received signal strength will increase even after the change, and in this case, the search frequency increases. However, it is unlikely that the communication situation will deteriorate rapidly immediately after the connection destination is changed. Therefore, according to the configuration of the present invention, by not changing the search frequency until a predetermined time elapses from the change of the connection destination, it is possible to prevent the search frequency from being increased unnecessarily, and a higher power saving effect can be expected.

  In the above wireless communication device, the search unit takes a moving average in the unit interval of the received signal strength measured by the received signal strength measuring unit, and whether the difference between the previous moving average value and the current moving average value is a predetermined threshold value or more. It is characterized by determining whether or not.

  According to the configuration of the present invention, the movement (transport) of the device main body can be accurately determined by taking the moving average in the unit section. In other words, it is possible to prevent the search frequency from becoming unnecessarily high by varying the search frequency based on the moving average in the unit interval, instead of varying the search frequency based on a temporary change in received signal strength, Higher power saving effect can be expected.

1 is a configuration diagram of a printing system according to an embodiment of the present invention. FIG. 2 is a block diagram illustrating a hardware configuration of a printer. FIG. 2 is a block diagram illustrating a functional configuration of a printer. It is a graph which shows an example of the measurement result of received signal strength. 3 is a flowchart illustrating a series of processes of the printer.

  Hereinafter, a wireless communication device and a method for controlling the wireless communication device of the present invention will be described with reference to the accompanying drawings. In the present embodiment, a case where the wireless communication device of the present invention is applied to the printer 1 is illustrated.

  FIG. 1 is a configuration diagram of a printing system SY according to an embodiment of the present invention. The printing system SY includes a printer 1, an access point 3 (3a, 3b), and a wireless network 5 that connects the two. The access point 3a and the access point 3b are installed at separate locations. For example, when the printer 1 exists at the position <A>, the access point 3a is the connection destination, and when the printer 1 exists at the position <B>. The access point 3b is the connection destination. In this way, the printer 1 periodically searches for the access point 3 and establishes a connection with the access point 3 discovered by the search. That is, the connection destination is changed by moving (transporting) the printer 1.

  The wireless network 5 is a wireless local area network (LAN) defined by, for example, IEEE 802.11x, and conforms to WiFi (registered trademark). The printer 1 of this embodiment and the two access points 3a and 3b are in a state in which a common network name (ESS-ID, SSID, etc.), authentication / encryption method, and encryption key are set in advance. . In the figure, two access points 3 are shown, but the number of access points 3 included in the printing system SY is arbitrary.

  The printer 1 is a mobile printer for issuing accounting receipts used in retail stores such as supermarkets and department stores. The printer 1 receives print data from a POS (Point of sale) terminal (not shown), prints on the long paper 10 (roll paper), and issues an accounting receipt by cutting the printed portion. .

  The access point 3 relays communication between clients (such as the printer 1 and the POS terminal) in the wireless network 5. When the access point 3 periodically transmits a beacon signal to the wireless network 5, the printer 1 as a client transmits a probe request for inquiring the network name to the access point 3 (searches for the access point 3). If the access point 3 has the same network name, it transmits a probe response. Thereby, both recognize the mutual existence. The search for the access point 3 may be a method of transmitting a probe request regardless of reception of a beacon signal, or a method of reading a network name included in a beacon signal.

  Thereafter, the access point 3 authenticates whether or not it is an official client using a preset authentication method. When it is determined that the client is an official client, the client makes a connection request to the access point 3. On the other hand, when the access point 3 sends a permission response, the connection between the two is established.

  Next, the hardware configuration of the printer 1 will be described with reference to FIG. The printer 1 includes a control mechanism 11, a wireless LAN driver 12, a wireless LAN module 13, and a printing mechanism 14.

  The printing mechanism 14 includes a print head 71 that performs printing, a paper transport motor 72 and a paper transport roller 73 that transport the paper 10, a paper cutter motor 74 and a paper cutter 75 that cut the paper 10.

  The control mechanism 11 includes a CPU (Central Processing Unit) 61, a network control firmware 62, and a print control firmware 63. The network control firmware 62 is firmware for performing communication control. The print control firmware 63 is firmware for controlling the printing mechanism 14. The CPU 61 performs communication control and print control based on the network control firmware 62 and the print control firmware 63. In particular, in this embodiment, as part of the communication control, the search frequency for searching for the access point 3 (scan cycle of the access point 3) is varied based on the measurement result of the received signal strength by the wireless LAN module 13. Details will be described later.

  The wireless LAN driver 12 operates the wireless LAN module 13 based on a command from the CPU 61. The wireless LAN module 13 is a module in which an RF (Radio Frequency) unit (not shown) and a wireless communication controller unit are integrated in addition to the antenna 13a. The RF unit outputs the analog information received from the antenna 13a to the wireless communication controller unit that digitizes the analog signal, and also converts the digital information generated by the wireless communication controller unit to analog and outputs it to the antenna 13a. Further, the wireless communication controller unit has a storage area for storing a MAC address and various setting information, and performs communication with the access point 3 based on these storage areas. Further, the wireless communication controller unit measures the received signal strength of the beacon signal transmitted from the access point 3, and outputs the measurement result to the control mechanism 11 via the wireless LAN driver 12.

  Next, the functional configuration of the printer 1 will be described with reference to FIG. The printer 1 includes a communication unit 110, a received signal strength measurement unit 120, a printing unit 130, and a search unit 140 as functional configurations.

  The communication unit 110 (wireless LAN module 13) performs wireless communication in an infrastructure mode. The received signal strength measurement unit 120 measures a change in received signal strength of the communication unit 110. That is, the transition of the signal strength on the time axis of the beacon signal received by the wireless LAN module 13 is measured. In the present embodiment, the movement of the printer 1 (device main body) is determined based on the measurement result of the received signal strength measurement unit 120 (search unit 140). The printing unit 130 prints on the paper 10, cuts the printed portion, and issues an accounting receipt.

  Search unit 140 searches for access point 3 (connection destination). In addition, when the change in the received signal strength measured by the received signal strength measuring unit 120 is equal to or greater than the predetermined threshold, the search frequency is set to the first value, and when the change in the received signal strength is less than the predetermined threshold, the search frequency is set to the first frequency. The second value is lower than the value of 1. That is, when the change in the received signal strength is large, the printer 1 is considered to be moving (carrying), and the search frequency is increased. On the other hand, when the change in the received signal strength is small, it is considered that the printer 1 is not moving (in a stationary state), and the search frequency is lowered. Thereby, useless power consumption when the printer 1 is stationary and the radio wave environment is in a stable state can be reduced. Hereinafter, the “first value search frequency” is referred to as a “first search frequency”, and the “second value search frequency” is referred to as a “second search frequency”. The “second search frequency” may be a search stop (search frequency zero).

  If the search frequency is lowered while the printer 1 is stationary as described above, a situation in which the search frequency is low even when the received signal strength is low occurs. However, due to the characteristics of the printer 1, printing is performed even when the received signal strength is low. There is no problem because there is little influence on operation and printed matter.

  On the other hand, when determining whether the change in the received signal strength is equal to or greater than a predetermined threshold, the search unit 140 calculates a moving average in the unit interval of the received signal strength measured by the received signal strength measuring unit 120 (calculates the average value of the interval). It is determined whether the difference between the previous moving average value and the current moving average value is equal to or greater than a predetermined threshold value. Thereby, it can be determined accurately whether the printer 1 is carrying.

  Here, the relationship between the measurement result of the received signal strength measurement unit 120 and the search frequency will be described with reference to FIG. In the figure, the vertical axis indicates the measurement value (reception signal strength) of the reception signal strength measurement unit 120, and the horizontal axis indicates time. Reference numeral 81 indicates a measurement waveform of the received signal strength, and reference numeral 82 indicates a moving average value in a unit interval of the received signal strength. As can be seen from the reference numeral 82, since the change in received signal strength is small after time t0 to t1, t2 to t3, and t4, the search unit 140 considers that the printer 1 is in a stationary state, and performs the second search. Search at a frequency. On the other hand, since the change in received signal strength is large during the times t1 to t2 and t3 to t4, the search unit 140 considers that the printer 1 is in a moving state, and searches at the first search frequency. Do.

  As an exception process, the search unit 140 sets the second search frequency when the printing unit 130 is in an error state even when the change in the received signal strength is equal to or greater than a predetermined threshold. That is, if the printing unit 130 is in an error state, it does not make sense to perform a search. Therefore, wasteful power consumption is reduced by reducing the search frequency. Note that the error state of the printing unit 130 includes a printing mechanism such as out of paper, paper jam, open cover of a roll paper container (not shown), out of ink / toner, paper cutter 75 error, abnormal temperature of the print head 71, and the like. 14 indicates a state in which an abnormality has occurred at a location related to 14.

  Next, a series of processing of the printer 1 will be described with reference to the flowchart of FIG. When the printer 1 is connected to the access point 3 after startup (S01: Yes), the wireless LAN module 13 starts measuring the received signal strength (S02), and sets the second search frequency (S03). In addition, it is preferable to perform a search at the first search frequency until the access point 3 is connected after activation.

  Thereafter, the moving average value of the received signal strength in the unit section is calculated (S04), and it is determined whether or not the difference between the moving average values of the previous unit section and the current unit section is greater than or equal to a predetermined threshold (S05). In the case of S05: Yes, that is, when it is determined that the difference in moving average value is large and the printer 1 is moving, it is determined whether or not the printing mechanism 14 (printing unit 130) is in an error state (S06). If it is determined that the printing mechanism 14 is not in an error state (S06: No), the first search frequency is set (S07), and the process returns to S04.

  On the other hand, if the difference between the moving average values of the previous unit section and the current unit section is less than the predetermined threshold value and it is determined that the printer 1 is not moving (S05: No), or the printing mechanism 14 (printing unit 130). Is determined to be in an error state (S06: Yes), the second search frequency is set (S08), and the process returns to S04.

  As described above, the printer 1 according to the present embodiment reduces the search frequency when the change in the received signal strength is less than the predetermined threshold compared to the case where the change in the received signal strength is greater than or equal to the predetermined threshold. That is, when the printer 1 can be estimated to be stationary, unnecessary searching when the radio wave environment is in a stable state can be suppressed by lowering the search frequency than when the printer 1 can be estimated to be moving. Power effect can be expected.

  Further, even when the change in the received signal strength is greater than or equal to a predetermined threshold, that is, when there is a high possibility that the radio wave environment is not stable, if the printing unit 130 is in an error state, an unnecessary search is performed to reduce the search frequency. And a higher power saving effect can be expected.

  In the present embodiment, the moving average of the received signal strength in the unit interval is taken, and the printer 1 is moved to determine whether the difference between the previous moving average value and the current moving average value is equal to or greater than a predetermined threshold value. It can be determined accurately. In other words, since the search frequency is not changed by a temporary change in received signal strength such as when a person approaches the printer 1 and blocks radio waves, the search frequency is prevented from being increased unnecessarily, and a higher power saving effect is expected. it can.

In addition, the following modifications can be employed.
[Modification 1]
For example, when the connection destination of the communication unit 110 is changed, the search unit 140 may be configured such that the search frequency is not changed until a predetermined time elapses after the change. When the connection destination is changed, there is a possibility that the change in the received signal strength will increase even after the change, and in this case, the search frequency increases. However, since it is unlikely that the communication situation will deteriorate rapidly immediately after changing the connection destination, it is not necessary to increase the search frequency unnecessarily by not changing the search frequency until a predetermined time has elapsed since the change of the connection destination. It can be expected to have higher power saving effect.

[Modification 2]
In the above embodiment, the search unit 140 varies the search frequency according to the change in the received signal strength, but may further vary the search frequency according to the amount of change. For example, if the amount of change is large, it can be estimated that the moving speed is fast, so it is conceivable to increase the search frequency. According to this configuration, an appropriate search frequency can be set according to the stability of the radio wave environment.

[Modification 3]
Further, the search unit 140 sets the first search frequency when the difference between the moving average value of the previous received signal strength and the moving average value of the current received signal strength is equal to or greater than a predetermined threshold, and sets the first search frequency when the difference is less than the predetermined threshold. However, the predetermined threshold value when the moving average value changes to the positive side and the predetermined threshold value when the moving average value changes to the negative side may be different values.

[Modification 4]
Further, the control for varying the search frequency according to the change in the received signal strength may be limited to the case where the received signal strength is equal to or greater than a predetermined value. That is, when the received signal strength is less than a predetermined value, the search frequency may be a fixed value regardless of the change in the received signal strength. In that case, since the received signal strength is weak, the first search frequency is preferable.

[Modification 5]
Further, instead of changing the search frequency according to whether or not the printer 1 is moving, it may be configured to switch between search execution and search stop.

[Modification 6]
In the above embodiment, the wireless communication device of the present invention is applied to the printer 1, but it can also be applied to other electronic devices. Further, the search unit 140 shown in the above embodiment may be realized by cloud computing.

[Other variations]
You may provide each component of printing system SY (printer 1) shown in said embodiment and modification as a program. The program may be provided by being stored in various recording media (CD-ROM, flash memory, etc.). That is, a program for causing a computer to function as each component of the printer 1 and a recording medium on which the program is recorded are also included in the scope of rights of the present invention. Other modifications can be made as appropriate without departing from the scope of the present invention.

  1: Printer 3: Access point 5: Wireless network 10: Paper 11: Control mechanism 12: Wireless LAN driver 13: Wireless LAN module 13a: Antenna 14: Printing mechanism 61: CPU 62: Network control firmware 63: Print control firmware 81: Received signal strength measurement waveform 82: Moving average value of received signal strength 110: Communication unit 120: Received signal strength measuring unit 130 Printing unit 140: Search unit SY: Printing system

Claims (5)

A communication unit for wireless communication;
A received signal strength measuring unit for measuring a change in received signal strength of the communication unit;
A search unit for searching for a connection destination of the communication unit,
When the change in the received signal strength measured by the received signal strength measurement unit is greater than or equal to a predetermined threshold, the search unit sets the search frequency to a first value, and the change in the received signal strength is less than the predetermined threshold The wireless communication device, wherein the search frequency is a second value lower than the first value. A printing section,
2. The search unit according to claim 1, wherein the search unit sets the search frequency to the second value when the printing unit is in an error state even when the change in the received signal strength is equal to or greater than the predetermined threshold. The wireless communication device described.   3. The wireless communication device according to claim 1, wherein, when the connection destination of the communication unit is changed, the search unit does not change the search frequency until a predetermined time elapses after the change.   The search unit takes a moving average in a unit interval of the received signal strength measured by the received signal strength measuring unit, and determines whether or not a difference between a previous moving average value and a current moving average value is equal to or greater than the predetermined threshold value. The wireless communication device according to claim 1, wherein the wireless communication device is determined. A method for controlling a wireless communication device including a communication unit,
A received signal strength measuring step for measuring a change in received signal strength of the communication unit;
Performing a search step of searching for a connection destination of the communication unit;
In the search step, when the change in the received signal strength measured in the received signal strength measurement step is equal to or greater than a predetermined threshold, the search frequency is set to a first value, and the change in the received signal strength is less than the predetermined threshold. In this case, the search frequency is set to a second value that is lower than the first value.

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