JP6111908B2 - Communication device and battery remaining capacity derivation method - Google Patents

Description

  The present invention is a communication device including a communication unit that performs communication with a peripheral device and a battery that supplies power to the communication unit, and a battery remaining capacity derivation method that is executed in the communication device. Especially, it is used for automatic meter reading system that automatically collects meter reading data such as gas meter and water meter, system that automatically collects information such as temperature and humidity, or security system that notifies information such as gas leak sensor and fire sensor. The present invention relates to a communication device and a battery remaining capacity derivation method executed in the communication device.

  Taking an automatic meter reading system of a gas meter as an example, one of the methods for detecting that the remaining capacity of the battery is reduced with respect to a battery mounted as a driving power source in a wireless communication terminal handled by this system is a battery. There is a method in which the replacement time is determined when the measured voltage falls below a reference voltage previously set in the apparatus. In this method, if the accuracy of measuring the battery voltage is poor, there is a problem that the capacity of the battery cannot be used sufficiently, and if excessive power is consumed in the measurement process, the battery capacity is reduced due to this process. Problems such as sudden stop. Therefore, it is necessary to accurately measure the battery voltage with a small amount of processing.

  As a method for measuring the battery voltage, examples conventionally proposed are listed in prior art documents (Patent Document 1, Patent Document 2, and Patent Document 3). In Patent Document 1 and Patent Document 2, after applying a load with discharge to a battery for a certain period of time, the battery is released from this load and then measured until the battery voltage is recovered. Has proposed a method of measuring the remaining capacity. Further, Patent Document 1 proposes that a communication operation in normal operation is used as a battery discharge load for measuring the remaining battery capacity. Patent Document 3 proposes a method for improving the accuracy of the voltage measurement result by determining whether or not re-measurement is necessary based on the result of voltage measurement after applying the load.

JP 2012-26778 A (FIG. 1) Japanese Patent Laid-Open No. 10-187295 (FIG. 2) JP 2011-217123 A

  Among conventional technologies, Patent Document 1 and Patent Document 2 apply a discharge load to a battery, measure the time until the voltage of the battery recovers after releasing the load, thereby recovering the voltage. The remaining battery capacity is derived from the time required. At this time, in order to measure the time required for the voltage to recover, it is necessary to periodically measure the voltage of the battery several times after releasing the load. However, it becomes a problem.

  Further, in Patent Document 3, when determining a decrease in battery capacity, a measured voltage of a battery is compared with a reference voltage held in advance using an absolute value, and there is a measurement error in the measured voltage value. If included, a problem of accuracy occurs in the measurement of the remaining battery capacity. For this reason, in this document, additional measurement of battery voltage and comparison processing with reference voltage are added, and accordingly, the cause of measurement error is correctly identified, and appropriate correction processing is performed based on the characteristics of the factor Since the process for deriving the remaining battery capacity becomes complicated due to necessity, an additional power consumption of the battery is an issue.

  An object of the present invention is to provide a communication device and a battery remaining capacity derivation method that can reduce power consumption associated with deriving the remaining capacity of a battery.

The present invention
In a communication device including a communication unit that performs communication with a peripheral device, and a battery that supplies power to the communication unit,
The battery depends on the remaining battery capacity that is the remaining capacity of the battery and the communication time from the start to the end of the communication,
The voltage difference between the voltage at the start of communication and the voltage at the end of the communication changes,
A voltage difference measuring unit for measuring the voltage difference of the battery;
A time measuring unit for measuring the communication time;
A relationship storage unit that stores a relationship between the communication time of the communication unit, the remaining battery capacity, and the voltage difference of the battery;
Based on the relationship stored in the relationship storage unit,
A battery remaining capacity deriving unit for deriving the battery remaining capacity using the voltage difference of the battery measured by the voltage difference measuring unit and the time measured by the time measuring unit;
A communication device further comprising:

The present invention
A communication unit for communicating with peripheral devices;
A battery remaining capacity derivation method executed in a communication device comprising a battery for supplying power to the communication unit,
A voltage difference measuring step for measuring a voltage difference between the voltage at the start of the communication and the voltage at the end of the communication in the battery;
A time measurement step of measuring a communication time from the start to the end of the communication;
Based on the characteristics of the battery in which the voltage difference changes depending on the battery remaining capacity that is the remaining capacity of the battery and the communication time,
A battery remaining capacity deriving step for deriving the battery remaining capacity from the voltage difference of the battery measured in the voltage difference measuring step and the communication time measured in the time measuring step;
A battery remaining capacity deriving method characterized by comprising:

  According to the present invention, the remaining capacity of the battery can be derived in parallel with the continuous communication operation periodically performed by the communication device in the communication system, and thus the communication device does not perform the communication operation. Since it is possible to take a power saving state promptly, the time for which the communication device operates for derivation of the remaining battery capacity in the prior art is shortened, and the effect of suppressing the power consumption and extending the battery life is obtained. .

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an overall configuration diagram showing a wireless communication system including devices in Embodiment 1 of the present invention. It is an internal block diagram which shows the subunit | mobile_unit radio | wireless machine in Embodiment 1 of this invention. It is a graph which shows the relationship between the communication time in the continuous communication operation | movement of the subunit | mobile_unit radio | wireless machine, and the voltage difference of a battery in Embodiment 1 of this invention. It is a table | surface which shows the remaining capacity of the battery which the subunit | mobile_unit radio | wireless machine uses in Embodiment 1 of this invention, the fall voltage of the said battery when the load of continuous communication operation | movement is applied, and its A / D conversion value. . It is a table | surface which shows the A / D conversion value of the fall voltage of the battery which the subunit | mobile_unit radio | wireless machine uses in Embodiment 1 of this invention, and the battery remaining capacity derived | led-out from the value. It is a flowchart figure which shows the periodic radio | wireless communication operation | movement which the subunit | mobile_unit radio | wireless machine performs in standby in Embodiment 1 of this invention. FIG. 7 is a flowchart showing details from a beacon signal collection process performed in process S17 to a battery drop voltage calculation process in FIG. 6 showing the operation of the slave radio in the first embodiment of the present invention. It is a flowchart figure which shows the operation | movement which the subunit | mobile_unit radio | wireless machine transmits data with respect to a peripheral radio | wireless apparatus, and the operation | movement which performs the continuous transmission operation | movement of a radio | wireless carrier signal in connection with it in Embodiment 2 of this invention. FIG. 7 is a flowchart in which processing for averaging the remaining battery capacity calculation results is added as Embodiment 3 based on FIG. 6 showing the operation of Embodiment 1 of the present invention.

Embodiment 1 FIG.
FIG. 1 is an overall configuration diagram showing a radio communication system configured by an apparatus according to Embodiment 1 of the present invention.

  The radio communication system includes a center server 11, an Internet network 12, a gateway 13, a master radio 14, a plurality of slave radios 15A to 15E, and a plurality of meters 16A to 16E.

  The center server 11 is connected to the Internet 12 and is a server device for monitoring and controlling a plurality of meters 16A to 16E from a remote location. Is a device that acquires information held by the mobile device and manages the state of the device such as the remaining battery capacity of the slave radio devices 15A to 15E. The information held by the meter here is, for example, meter reading information of a gas meter. It should be noted that various other communication forms such as a wired telephone network or a combination of a wired telephone network and a mobile wireless communication network are allowed instead of the Internet network 12.

  The Internet network 12 is an Internet facility network such as a wide area network generally used as communication infrastructure equipment or a special network owned by a business operator.

  The gateway 13 is a communication device for interconnecting the Internet network 12 and a local network formed by the parent radio 14, and relays data transmitted and received between the center server 11 and the parent radio 14. Equipment.

  The base radio 14 is a communication device for interconnecting the gateway 13 and a radio network composed of a plurality of radios of the base radio 14 and the slave radios 15A to 15E. And a wireless communication function with a plurality of slave wireless devices 15A to 15E. Further, in relaying the meter reading request from the center server 11 to each meter 16A to 16E and the meter reading information from each meter 16A to 16E as the response, a communication path constituted by the slave radio units 15A to 15E It is also possible to provide a function of selecting a transfer destination slave radio that is the optimum route. Here, the optimum route differs depending on the purpose, such as a route with the smallest number of relays and a route with the least power consumption as a system.

  The slave radio devices 15A to 15E are communication devices for relaying communication between the center server 11 and the meters 16A to 16E. The slave radio devices 15A to 15E function to communicate with the connected meters 16A to 16E, 14 and the slave radio devices 15A to 15E are devices having a function of performing wireless communication with each other. Further, when relaying communication, it is also possible to have a function of selecting a transfer destination wireless device that is the optimum route among communication routes configured by the parent device wireless device 14 and the child device wireless devices 15A to 15E. . Here, the optimum route differs depending on the purpose, such as a route with the smallest number of relays and a route with the least power consumption as a system. Further, the number of slave radio units can be increased or decreased as appropriate in accordance with the network configuration in addition to five.

  Meters 16A to 16E are measuring instruments such as gas meters and water meters, or measuring instruments that measure temperature, humidity, and the like. The meters 16A to 16E are provided in a device serving as an information source of main information handled by the system. It is a device for obtaining.

  In FIG. 1, a mesh network is used as a wireless network between the master radio 14 and the slave radios 15A to 15E, but the mesh type can be changed by appropriately changing the arrangement of the radios. In addition to the network, a star network or a cluster tree network may be used.

  Further, in the configuration of the mesh network, for example, even in a situation where the base radio 14 and the slave radio 15D cannot communicate directly, the slave radio 15A capable of communicating with both radios is provided. By existing in this period, data from the master radio 14 and slave radio 15D is transferred by the slave radio 15A, and the master radio 14 and the slave radio 15D can communicate by relay. Become. As described above, in a network configuration that uses relay for communication, it is possible to include in the network configuration a slave unit radio that is dedicated for relay and does not connect a meter.

  When the system of FIG. 1 is applied to, for example, an automatic meter reading system that automatically collects meter reading information of a gas meter, meter reading information can be collected as follows.

  When the center server 11 acquires meter reading data of the meter 16E, meter reading request data is transmitted from the center server 11 to the gateway 13 connected to the wireless network to which the meter 16E to be metered belongs, and the data is received. Then, the gateway 13 transfers the data to the base radio unit 14.

  The base station radio 14 that has received the data transfers the data to the handset radio 15E because the handset radio 15E to which the meter 16E to be metered is connected is not in a directly communicable range. In addition, it is necessary to relay one or a plurality of slave radios among the slave radios 15A to 15D. When selecting the route that transfers the data to the child device wireless device 15E that minimizes the number of relays, the parent device wireless device 14 determines that the route that relays the child device wireless device 15A is optimal. Based on this, the data is transmitted to the slave radio 15A.

  The slave radio 15A that has received the data from the master radio 14 is not in a range in which the slave radio 15E can communicate directly, so the number of relays to the slave radio 15E is the same as the master radio 14. Is selected so that the data is routed to the minimum, and based on the result, the data is transmitted to the slave radio 15D. Thereafter, by repeating the relay operation in the same manner, the data is transferred to the slave radio 15E.

  The handset radio 15E that has received the meter reading request data communicates with the connected meter 16E to obtain meter reading information. The subunit | mobile_unit radio | wireless machine 15E which acquired the meter-reading information of the meter 16E transmits the data containing the said meter-reading information with respect to the center server 11. FIG. At this time, since the slave radio 15E is not in a range in which the master radio 14 can communicate directly, one or more slave radios among the slave radios 15A to 15D are relayed. Attempts to transfer the data to the base radio unit 14. The relay operation that is performed earlier is the same as that in which data is transferred from the master radio unit 14 to the slave radio unit 15E.

  Receiving the data from the slave radio 15E, the master radio 14 relays the gateway 13 and transfers the data to the center server 11. The center server 11 that has received the data acquires the meter reading information of the meter 16E included in the data, and the collection of the meter reading information of the meter 16E is completed. Meter reading information is collected in the same manner for other meters.

  The base unit radios and slave unit radios 15A to 15E constituting the system may operate asynchronously, or may synchronize the periodic operations of the radio units described later. When synchronized, each wireless device efficiently transmits and receives data, thereby reducing the power consumption of the provided battery and extending the life of the battery.

  In Embodiment 1, beacon signals are transmitted and received when slave radio units 15A to 15E communicate with each other. The slave radio uses a battery as an operating power source, and takes an operation state (hereinafter referred to as a sleep state) in which power consumption is periodically suppressed in order to suppress battery consumption. Therefore, when the slave unit radio transmits data, it is necessary to know that the destination slave unit to which data is to be transmitted is not in a sleep state. The beacon signal transmitted by the slave radio is received.

  The beacon signal includes a unique number (hereinafter referred to as a wireless device number) for identifying the wireless device, and the wireless device number included in the received beacon signal is transmitted by the slave wireless device. It is determined whether or not it matches that of the destination slave radio. When it is determined that the beacon signal is received from the addressed slave wireless device by the wireless device number determination, for example, the “CSMA / CA (Carrier Sense Multiple Access / Collision Avoidance) method” is performed to After confirming that the transmission data does not collide with the mobile radio, a transmission request signal is transmitted as a response to the beacon signal. The slave radio that has transmitted the transmission request signal subsequently transmits data to the destination slave radio.

  In this way, the slave unit radio can periodically receive a beacon signal to obtain the opportunity to receive data from neighboring slave unit radios, and conversely, by receiving the beacon signal, It is possible to obtain an opportunity to transmit data to the slave wireless device.

  In addition, by acquiring the radio number included in the beacon signal, it is possible to create a list of slave radios existing in the vicinity. The slave radio performs periodic beacon signal continuous reception operations, creates or updates the list each time, and has information on the optimum data transfer path according to the purpose based on the list Can do.

  FIG. 2 is an internal configuration diagram of slave radio devices 15A to 15E in the first embodiment.

  The slave radio device includes a radio communication antenna 21, a radio unit 22, a CPU unit 23 as a central processing unit, a meter interface 24, and a battery 25. Further, the radio unit 22 includes a receiving unit 221 and a transmitting unit 222. The CPU unit 23 includes a ROM (read only memory) 231, a RAM (random access memory) 232, and an A / D converter 233.

  The wireless communication antenna 21 is connected to the wireless unit 22 and is a communication antenna that transmits and receives communication radio waves in order for the slave wireless device to perform wireless communication with peripheral wireless devices.

  The radio unit 22 is connected to the radio communication antenna 21, the CPU unit 23, and the battery 25. The radio unit 22 operates under the control of the CPU unit 23 using the battery 25 as a driving power source. This is a device that controls the internal reception unit 221 and transmission unit 222 when performing wireless communication with the wireless communication device.

  The CPU unit 23 is connected to the wireless unit 22, the meter interface 24, and the battery 25, and controls the wireless unit 22 and the meter interface 24 by using the battery 25 as a driving power source. This device controls the overall operation of the radio.

  The meter interface 24 is connected to the CPU unit 23 and the meter 16, and is a device that acquires meter reading information from the meter 16 under the control of the CPU unit 23.

  The battery 25 is connected to the radio unit 22 and the CPU unit 23, and is a power source that supplies current to the devices constituting the slave radio.

  The receiving unit 221 is a device that is provided inside the wireless unit 22 and controls data reception in wireless communication between the slave wireless device and peripheral wireless devices under the control of the wireless unit 22.

  The transmission unit 222 is a device that is provided inside the wireless unit 22 and controls transmission of data in wireless communication between the slave wireless device and peripheral wireless devices under the control of the wireless unit 22.

  The current I_BATT 26 is a current supplied from the battery 25 to the reception unit 221 and the transmission unit 222 inside the wireless unit 22 under the control of the CPU unit 23.

  The ROM 231 is a nonvolatile storage device that is provided inside the CPU unit 23 and stores programs and data regardless of whether or not current is supplied from the battery 25.

  The RAM 232 is a storage device that is provided inside the CPU unit 23 and temporarily stores data.

  The A / D converter 233 is provided inside the CPU unit 23, and uses the battery 25 as a driving power source, and measures the voltage of the battery 25 by quantification by A / D conversion under the control of the CPU unit 23. It is.

  FIG. 3 is a graph of the characteristics related to the communication time and the voltage difference shown by the battery 25. 3A and 3B, the horizontal axis represents time, and the vertical axis represents the voltage value of the battery at each time. Time T1 is a time at which the communication operation of the communication device with the battery discharge load is started, and time T2 is a time at which the communication operation started at time T1 is stopped. The difference between time T2 and time T1 is defined as time ΔT. The voltage V1 is the voltage value of the battery at time T1, and the voltage V2 is the voltage value of the battery at time T2. A voltage difference between the voltage V1 and the voltage V2 is defined as a drop voltage ΔV. Here, it is assumed that the remaining battery capacity in FIG. 3A is larger than the remaining battery capacity in FIG.

  When a constant discharge load is continuously applied to the battery 25, the battery voltage changes as shown in FIG. As one of the characteristics in the change of the voltage, with time ΔT, the drop voltage ΔV gradually drops from the voltage V1 to the voltage V2 without changing rapidly. After the discharge load stops, the battery voltage recovers with time. Further, as another feature, when the remaining capacity of the battery is small, that is, in the case of FIG. 3B compared to FIG. 3A, the drop voltage ΔV at time ΔT becomes large.

  The battery 25 handled here is a primary battery using a lithium aluminum alloy as a negative electrode, and the battery does not use a lithium aluminum alloy as a negative electrode in order to maintain a low internal resistance even at a deep discharge depth. The characteristics shown in FIG. As the battery 25, a battery having the same characteristics as those in FIG. 3 can be used.

  The result of applying the characteristics of the battery 25 to the first embodiment is shown in FIG. In the first embodiment, it is assumed that the current value I_BATT 26 of the discharge load applied to the battery 25 is constantly 20 mA when the slave radio performs a continuous reception operation for 20 seconds as a collection process of beacon signals. . At this time, FIG. 3A shows a state where the remaining capacity of the battery before applying the discharge load is 40%, and FIG. 3B shows a state where the remaining capacity of the battery before applying the discharge load is 10%. To do. The time ΔT in FIGS. 3A and 3B is 20 seconds.

  In FIG. 3A, the voltage V1 at time T1 when the slave radio starts the continuous reception operation is 2.80V, and the voltage V2 at time T2 when the continuous reception operation is stopped is 2.75V. In FIG. 3B, voltage V1 at time T1 when the slave radio starts a continuous reception operation is 2.69V, and voltage V2 at time T2 when the continuous reception operation is stopped is 2.60V.

  FIG. 4 is a table in which the results of applying Embodiment 1 are arranged based on the characteristics of the battery 25 of FIG. The remaining capacity of the battery 25 before the discharge load is applied, the voltage V1 and the voltage V2 that are the voltage values before and after the discharge load is applied to the battery 25 for the time ΔT, and the voltage difference between the voltage V1 and the voltage V2 The relationship with the voltage ΔV is shown. Here, the A / D converter in the CPU 23 is a 10-bit A / D converter, and the input voltage is 3.00 V and the full range is 1023LSB. Here, LSB (Least Significant Bit) is a quantization unit in A / D conversion.

  In the first embodiment, each state in which the remaining capacity of the battery 25 is about 80%, about 40%, and about 10% is shown as No. in the table. 1, no. 2, no. 3 when the discharge load to the battery 25 associated with the continuous reception operation of the slave radio is applied at a time ΔT of 20 seconds as in FIG. 3, the battery immediately after the start of the load application and immediately before the stop The voltage V1 and the voltage V2 of 25, the drop voltage ΔV obtained as a difference between them, and the A / D converter 233 in the CPU 23 quantifies the values of the voltage V1, the voltage V2, and the drop voltage ΔV. The D conversion value is as shown in FIG.

  For example, in FIG. In the second case, when the remaining capacity of the battery 25 is about 40%, the voltage value of the drop voltage ΔV is 0.05 V, and the A / D conversion value at that time is 17 LSB. In addition, in FIG. In the case 3, the voltage value of the drop voltage ΔV is 0.09 V when the remaining capacity of the battery 25 is about 10%, and the A / D conversion value at that time is 31 LSB.

  As shown in these two cases, the A / D conversion value of the drop voltage ΔV changes according to the remaining capacity of the battery. In addition, the numerical values described in FIGS. 3 and 4 are examples, and differ depending on the battery and A / D converter used.

  3 and 4 are used, the time ΔT, which is the communication time of the wireless device, and the drop voltage ΔV, which is the voltage difference of the battery that accompanies it, are input, and the ratio of the remaining capacity of the battery is derived. I can do it. Further, in the process of deriving the remaining capacity of the battery, when the time ΔT is fixed to, for example, 20 seconds, the remaining capacity of the battery can be obtained corresponding to the value of the drop voltage ΔV obtained by the measurement. .

  FIG. 5 shows a discharge in which the current value I_BATT 26 is constantly 20 mA with respect to the battery 25 with a time ΔT of 20 seconds in accordance with the continuous reception operation of the slave radio in the first embodiment, as in FIG. 7 is a table for deriving the remaining capacity of the battery 25 from the voltage drop ΔV as an A / D conversion value measured by the A / D converter 233 during the load.

  The remaining capacity of the battery 25 is expressed as a percentage such that the battery 25 is 100% fully charged and the end-of-discharge voltage is 0%, and the remaining capacity expressed as a percentage is appropriate for the determination. Divide by range. In the right column of the table of FIG. 5, division is performed by rounding off the decimal point to four ranges of 61% or more, 60% to 31%, 30% to 11%, 10% or less.

  Then, for the battery 25 corresponding to each division of the remaining battery capacity expressed as a percentage, the value of the drop voltage ΔV is obtained from the actual measurement using the A / D converter 233, whereby the table of FIG. 5 is obtained.

  By referring to the table in FIG. 5, if the voltage drop ΔV of the battery 25 is obtained using the A / D converter 233, the remaining capacity of the battery can be derived. For example, when the A / D conversion value of the drop voltage ΔV is 15 LSB, it can be determined that the remaining capacity of the battery 25 is about 60% to 31%. Strictly speaking, the remaining capacity of the battery before the drop voltage ΔV is generated in the battery 25 is derived by using FIG. 5, but in the system to which the present invention is applied, one continuous communication is performed. Since it can be said that the remaining capacity of the battery hardly changes in operation, it is treated that the remaining battery capacity is substantially the same even after the drop voltage ΔV is generated.

  Further, the remaining capacity of the battery 25 can be determined more finely by making the division between the remaining capacity of the battery 25 and the drop voltage ΔV in FIG. 5 into a finer range.

  The table in FIG. 5 is prepared in advance so that the battery to be used, the A / D converter, and the conditions of the applied load are the same as those actually used, and are stored in the ROM 231 in the wireless device. It is necessary to keep.

  FIG. 6 is a flowchart showing a periodic operation performed by a slave radio device in standby without data transmission processing addressed to peripheral radio devices in the first embodiment.

  Here, the periodic operation during standby of the slave unit radio means an intermittent operation performed by a slave unit radio using a battery as a driving power source to achieve continuous operation for several years. . The intermittent operation is, for example, that the wireless unit is operated for several milliseconds every 10 seconds and the power consumption is reduced during other periods.

  Also, in order to prevent the slave radio from stopping during operation due to the battery life, the slave radio can measure the remaining capacity of the battery repeatedly during intermittent operation, so that it can be replaced with a new battery. When it is determined that the battery capacity has decreased, it is necessary to issue an alarm to the outside, for example, by notifying the server via wireless communication.

  The slave wireless device first transitions to step S11 as a standby operation. In process S11, in order to suppress battery consumption, the wireless unit 22 and the CPU 23 are set in a sleep state in which they are operated with low power consumption. Here, at the same time as the slave radio first transits to the process S11, the timer (a) is started, and the timer is also operating during the process S11. Here, the duration of the sleep state taken by the slave radio is set as time Ta (hereinafter, treated as 10 seconds). This time Ta depends on the specifications of the applied system, the battery to be used, or the slave radio, and can be changed in consideration of these. Thereafter, the process proceeds to process S12.

  In process S12, in order to cancel the sleep state after the time Ta has elapsed, it is determined whether the timer (a) has elapsed for the time Ta. Until it is determined in this process that the timer (a) has elapsed by the time Ta, the process transits to the process S11 to continue the sleep state, and the process S11 and the process S12 are alternately repeated.

  If it is determined in process S12 that the timer (a) has elapsed by the time Ta, the process shifts to process S13 without shifting to process S11, and the sleep state is released.

  In step S13, the slave radio switches to a data transmission operation and transmits a beacon signal to the peripheral slave radios. The beacon signal transmission period is as short as 2 ms. In step S13, the timer (a) is reset. After transmitting the beacon signal, the slave radio switches to a data reception operation and transitions to process S14.

  In the process S14, a process for determining whether or not a transmission request signal from a peripheral slave radio is received is performed. The transmission request signal is transmitted as a response to the beacon signal when the slave radio that has received the beacon signal wants to transmit data to the slave radio that is the transmission source of the beacon signal. If it is determined in step S14 that the transmission request signal has been received, the process proceeds to step S15. If it is not determined in step S14 that the transmission request signal has been received, the process proceeds to step S16 without performing step S15.

  In process S15, the data transmitted subsequently from the slave radio device that transmitted the transmission request signal is received. The data is transmitted immediately after the transmission of the transmission request signal is completed. After receiving the data, the process proceeds to process S16.

  In process S16, the slave radio performs a determination for periodically collecting beacon signals. When the period is set to time Tb (hereinafter, referred to as 72 hours), and the timer (b) started together with the timer (a) in process S11 has elapsed for the time Tb, the slave unit radio proceeds to process S17. Transition and perform a beacon signal collecting operation. If the timer (b) has not passed the time Tb, the process proceeds to step S11 to enter a sleep state. Here, the time Tb depends on the specifications of the system to be applied, the battery to be used, or the slave radio, and can be changed in consideration of these.

  In the process S17, a continuous reception operation for a beacon signal collecting operation is performed. Along with this continuous reception operation, a constant current value I_BATT 26 (hereinafter referred to as 20 mA) flows from the battery 25. In Embodiment 1 of the present invention, the discharge load on the battery at this time is utilized. The battery drop voltage ΔV is calculated. Details of each process of the process S17 are described in the flowchart of FIG. 7. These processes will be described later with reference to FIG. 7, but the calculation result of the battery drop voltage ΔV is obtained through the process S17. Is output. In step S17, the timer (b) is reset. After process S17, the process proceeds to process S18. Here, the current value I_BATT 26 depends on the specifications of the applied system, the battery to be used, or the slave radio, and can be changed in consideration of these.

  In the process S18, the remaining battery capacity corresponding to the battery drop voltage ΔV output in the process S17 is derived based on the table of FIG. With the derivation result of process S18, the process proceeds to process S19.

  In process S19, the battery remaining capacity derived | led-out by process S18 and the threshold value previously set to the subunit | mobile_unit radio | wireless machine are compared and determined. This threshold value is a value for determining that the battery capacity of the battery 25 has decreased and that the battery needs to be replaced. For example, if the threshold is set to 10% of the remaining battery capacity, it can be determined that the battery capacity has decreased when the remaining capacity is 10% or less, and the battery capacity when the remaining capacity is greater than 10%. It can be judged that has not decreased.

  If it is determined in step S19 that the remaining battery capacity is greater than the threshold value, the process proceeds to step S11 to enter a sleep state. If it is determined in process S19 that the remaining battery capacity is equal to or less than the threshold, the process proceeds to a battery capacity decrease alarm process in process S20. Here, the threshold value used as a criterion for the decrease in battery capacity depends on the applied system, the battery to be used, or the specifications of the slave radio, and can be changed in consideration of these.

  In the process S20, the slave radio device notifies the center server 11 by communication means that the battery capacity is decreasing. Thereafter, in response to the notification to the center server 11, a system maintenance person takes measures such as replacing the battery of the slave radio. In addition to the notification to the center server 11 by the communication means, for example, the slave radio device is provided with an external interface means such as LED display and audio output, so that an alarm that the battery capacity has decreased is given to the outside. It is possible to emit. After the process S20, it is possible to transition to the process S11 and take a sleep state, or to stop the operation of the apparatus without transitioning to the process S11.

  FIG. 7 is a flowchart showing details of each process performed in process S17 of FIG. First, in process S171, CPU23 controls the receiving part 221 in the radio | wireless part 22, and starts reception operation | movement of a subunit | mobile_unit radio | wireless machine. As described in step S <b> 17 of FIG. 6, a constant current value I_BATT 26 flows from the battery 25 along with this reception operation. The current value I_BATT 26 before starting the reception operation is 1 mA or less, and the increase / decrease range of the current value during the reception operation is about ± 1 mA, and the current value is almost constant and stable. In process S171, the timer (c) is started in accordance with the start of the receiving operation. After the reception operation is started, the process proceeds to process S172. The reception operation is continued so that the discharge load of the battery 25 is continuous and steady until it is stopped in the process S176 described later. A beacon signal is received from the slave radio.

  In process S172, the battery voltage is measured for the first time using the A / D converter 233 in the CPU 23. The battery voltage at this time corresponds to the voltage V1 in FIG. After measuring the voltage, the process proceeds to process S173.

  In process S173, beacon signals are collected from the peripheral slave radios. The radio number acquired from the collected beacon signals is appropriately stored in the RAM 232 in the CPU 23 as necessary. After collecting the beacon signals, the process proceeds to the determination process of process S174.

  In process S174, it is determined using the timer (c) started at the start of the reception operation that the reception operation has passed for a predetermined time. If this predetermined time is time Tc, beacon signals are collected in the continuous reception operation. Therefore, the time Tc is set to be longer than the sleep state time Ta taken by the peripheral wireless devices in the vicinity, and the reception of the beacon signal is ensured. Need to be able to. Hereinafter, the time Tc is set to 20 seconds, which is twice the time Ta. The time Tc depends on the specifications of the applied system, the battery to be used, or the slave radio, and can be changed in consideration of these.

  If it is determined in process S174 that the reception operation has not elapsed for the time Tc, the process proceeds to process S173 to collect a beacon signal. When it is determined that the reception operation has elapsed for the time Tc, the process proceeds to process S175.

  In the process S175, the battery voltage is measured for the second time using the A / D converter 233 in the CPU 23. The battery voltage at this time corresponds to the voltage V2 in FIG. After measuring the voltage, the process proceeds to process S176.

  In process S176, the CPU 23 controls the reception unit 221 in the wireless unit 22, and stops the reception operation started in process S171. The timer (c) is also stopped when the reception operation is stopped. Then, the process proceeds to process S177.

  In step S177, a list of wireless device numbers held in the RAM 232 in step S173 is created. The list is used to select a slave radio device to which data is transmitted when performing a data relay operation, an alarm process for low battery capacity, or the like. In the process S177, the timer (b) is also reset. Thereafter, the process proceeds to operation S178.

  In the process S178, the voltage drop ΔV as the A / D conversion value of the battery 25 generated by the continuous reception operation is calculated from the two battery voltage measurement results in the processes S172 and S175, and output as the result of the process S17. I do.

  According to the first embodiment of the present invention, as described with reference to FIGS. 6 and 7, the remaining capacity of the battery is derived in parallel with the continuous communication operation periodically performed by the wireless device in the wireless communication system. Thus, as in the prior art, it is possible to shorten the time for which the apparatus operates extra for the purpose of measuring the remaining battery capacity. As a result, in a situation where the wireless device does not perform a communication operation, it is possible to quickly take a state in which power consumption is suppressed, and an effect of extending the life of the battery can be obtained.

  Further, in the present invention, as described with reference to FIGS. 3, 4, and 5, the remaining battery capacity is derived from the battery drop voltage ΔV accompanying the discharge load, and the battery drop voltage is measured by measuring the battery voltage. Since this measurement error is offset because of the difference in the results, it is not necessary to perform complicated correction processing to derive the remaining battery capacity, and the battery power consumption can be reduced by that amount. The effect of extending is obtained.

Embodiment 2. FIG.
In the first embodiment, the continuous reception operation in the reception unit 221 in the wireless unit 22 is used as the discharge load when measuring the remaining capacity of the battery. The transmission unit 222 in the wireless unit 22 is used for this discharge load. It is also possible to use a continuous transmission operation at. A mode in which the continuous transmission operation in the transmission unit 222 in the radio unit 22 is handled for the measurement of the remaining capacity of the battery is a second embodiment of the present invention.

  In the second embodiment, the configuration of the entire system and the configuration of the slave radio are as shown in FIGS. 1 and 2 as in the first embodiment. Here, as in the first embodiment, the network configuration can take a configuration other than the mesh type network, and a slave radio device dedicated for relay can be included in the network configuration.

  The wireless communication system handled in the second embodiment involves a carrier sense operation when communication is performed between wireless devices, and a slave wireless device having transmission data transmits a predetermined time just before transmitting the transmission data. A radio carrier signal is continuously transmitted. The continuous transmission operation of the radio carrier signal at this time is used as a battery discharge load for measuring the remaining battery capacity.

  A slave radio that does not have data to be transmitted periodically takes a sleep state, and receives a carrier signal from a peripheral slave radio by performing carrier sense while canceling the sleep state. The slave radio that has received the radio carrier signal transmits a response signal to the slave radio that is the transmission source of the signal after transmission of the signal is stopped.

  The slave radio having the data to be transmitted stops the transmission operation after transmitting the radio carrier signal, and switches to the reception operation in order to receive a response signal from the peripheral slave radio. During this reception operation, when a response signal is received from the slave radio that is the destination of the transmission data, the transmission operation is again switched to start transmission of the transmission data.

  FIG. 8 is a flowchart illustrating an operation in which the slave unit radio transmits data to the peripheral slave unit radio units and a continuous transmission operation of radio carrier signals performed at that time in the second embodiment.

  A transmission operation is started on the condition that some transmission data is obtained, such as obtaining meter reading information from a meter to which a slave radio is connected or receiving relay data from a peripheral slave radio. First, the process proceeds to step S801 to transmit the transmission data.

  In process S801, CPU23 controls the transmission part 222 in the radio | wireless part 22, and starts transmission operation | movement of a subunit | mobile_unit radio | wireless machine. During this transmission operation, the slave radio continues to transmit a radio carrier signal. Here, as in the first embodiment, the constant current value flowing from the battery 25 in accordance with this transmission operation is I_BATT 26 (20 mA). In addition, the current value I_BATT 26 before starting the transmission operation is 1 mA or less, and the current value during the transmission operation is almost constant and stable with an increase / decrease range of about ± 1 mA.

  In process S801, the timer (c) is started in accordance with the start of the transmission operation. It is assumed that the transmission operation is continued so that the discharge load of the battery 25 is continuous and steady until it is stopped in process S805 described later. After the transmission operation is started, the process proceeds to process S802.

  The first battery voltage measurement process in the process S802 is the same as the process S172 of FIG. 7 in the first embodiment. After step S802, the process proceeds to step S803.

  The process of determining that the transmission operation in process S803 has elapsed for time Tc is the same as process S174 of FIG. 7 in the first embodiment. If it is determined in step S803 that the time Tc has elapsed, the process proceeds to step S804. If it is determined that the time Tc has not elapsed, the determination process in step S803 is performed again.

  The second battery voltage measurement process in process S804 is the same as the process S175 of FIG. 7 in the first embodiment. After process S804, the process proceeds to process S805.

  Here, when the period of the sleep state that the slave unit radio having no data to transmit is periodically taken as time Ta, the time Tc of the continuous transmission operation for continuously transmitting the radio carrier signal is determined by the peripheral slave unit radio. It is necessary to set the time longer than the time Ta in order to cancel the sleep state and reliably receive the radio carrier signal in the carrier sense. Here, as in the first embodiment, the time Tc is twice the time Ta.

  In process S805, CPU23 controls the transmission part 222 in the radio | wireless part 22, and stops the transmission operation started by process S801. When the transmission operation is stopped, the timer (c) is also stopped. Thereafter, the process proceeds to operation S806.

  In process S806, when a response signal transmitted from a peripheral slave radio apparatus is received and the response signal transmitted from the slave radio apparatus that is the destination of the transmission data is included in the response signal, the process proceeds to process S807. Transition. If there is no response signal from the slave radio set as the destination, the process proceeds to process S808 without performing process S807.

  In process S807, data transmission is performed to the slave wireless device serving as the destination. Thereafter, the process proceeds to operation S808.

  The battery remaining capacity calculation process in the process S808 is the same as the process S178 of FIG. 7 in the first embodiment. After step S808, the process proceeds to step S809.

  The battery remaining capacity deriving process in the process S809 is the same as the process S18 of FIG. 6 in the first embodiment. After step S809, the process proceeds to step S810.

  The comparison determination process between the remaining battery capacity and the threshold value in the process S810 is the same as the process S19 of FIG. 6 in the first embodiment. In process S810, when it determines with battery remaining capacity being below a threshold value, it transfers to process S811, and when it determines with it not being below a threshold value, a transmission operation is complete | finished.

  The battery capacity reduction alarm process in the process S811 is the same as the process S20 of FIG. 6 of the first embodiment. After the process S811, the transmission operation is terminated.

  Here, with respect to the characteristics of FIG. 3 that is the basis for the derivation of the remaining battery capacity in the process S809, the same is true even if the continuous reception operation in the first embodiment is replaced with the continuous transmission operation in the second embodiment. Battery voltage drop characteristics can be obtained, and FIGS. 4 and 5 accompanying FIG. 3 can be similarly applied to the second embodiment.

  After the transmission operation is completed, the operation is switched to the reception operation and the intermittent reception operation is performed. In the intermittent reception operation, the sleep state and the operation for data reception including carrier sense are repeated periodically. When a radio carrier signal is detected from the peripheral slave radio device at the time of carrier sense, a response signal is returned to the radio device, and if there is transmission data from the radio device thereafter, it is received. In addition, if there is meter reading information from the connected meter, this is received. When data to be transmitted is obtained in the intermittent reception operation, the transmission operation is started.

  In addition, when the transmission operation is finished through the battery capacity reduction alarm process in step S811, it is possible to stop the operation of the apparatus without performing the intermittent reception operation.

  According to the second embodiment of the present invention, the continuous transmission operation of the slave radio can be used as a discharge load to the battery in the process of deriving the remaining capacity of the battery. Thus, as in the first embodiment, the operation of the device to derive the remaining battery capacity can be reduced, and the power consumption of the battery can be suppressed, so that the effect of extending the battery life can be obtained.

  In addition, in the specification of the wireless communication system, even if the beacon signal is not used, or the beacon signal is used but the continuous reception operation is not necessary, the effect of the present invention can be achieved as long as the continuous transmission operation is performed. Can be obtained.

Embodiment 3 FIG.
In the first and second embodiments of the present invention, the difference between the measurement results of the battery voltage is handled in the process of deriving the remaining battery capacity, thereby reducing the effect of errors included in the measurement results. As described above, the third embodiment provides means for reducing the error itself included in the measurement result.

  The measurement error included when measuring the voltage using the A / D converter 233 of FIG. 2 is as follows.

  In general, the A / D converter generates a signal that becomes a constant reference by the driving voltage supplied from the battery, and the voltage measurement is the signal that becomes the reference and the input signal obtained by the voltage measurement. Is to compare. Hereinafter, a reference signal is referred to as a reference voltage, and an input signal obtained by measuring the voltage is referred to as a measurement voltage.

  However, the voltage supplied by the battery varies gradually due to changes in the external environment over time, such as ambient temperature, and the aging of the battery. Due to these factors, the voltage supplied to the A / D converter is increased. When fluctuation occurs, the reference voltage and measurement voltage obtained from the A / D converter are different from those when no fluctuation occurs. A change in the reference voltage and the measurement voltage caused by such a change in the supply voltage of the battery is a main measurement error.

  Regarding the above measurement error, regarding the voltage fluctuation caused by the aging of the battery, it is conceivable to replace the deteriorated battery at an appropriate time, or to use a battery whose characteristic change due to the aging is small. The appropriate time refers to, for example, before the voltage supply from the battery to the device becomes insufficient.

  On the other hand, with regard to voltage fluctuations due to changes in the external environment over time, the fluctuations have a periodic nature, so by averaging the measurement results of multiple battery voltages in that period. Measurement errors can be reduced. In the third embodiment, the remaining capacity of the battery is derived through the process of averaging changes depending on a certain period as described above.

  In the case of applying the third embodiment based on the first embodiment, assuming that the time Tb, which is the period for collecting the beacon signal by the slave radio, is 80 hours, for example, the measurement of the battery drop voltage ΔV is 3 days. Since the time of the measurement result can be shifted by 8 hours each time, if the measurement result of the drop voltage ΔV of the battery used for averaging is set to the latest three times, for example, 0:00 and 8:00 It is possible to suppress measurement errors due to environmental changes resulting from differences in time zones, such as averaging measurement results at 16:00.

  When the third embodiment is applied based on the second embodiment, the frequency of measurement results required to obtain the average of the battery drop voltage ΔV is different because the transmission frequency of the radio carrier signal differs for each slave radio. Needs to be set for each system or for each slave radio.

  FIG. 9 shows a flowchart when the third embodiment is applied based on the first embodiment. Here, the time Ta is 10 seconds, the time Tb is 80 hours, the time Tc is 20 seconds, and the measurement result of the battery drop voltage ΔV used for averaging is three times.

  The processing from processing S901 to processing S907 is the same as the processing from processing S11 to processing S17 in FIG. 6 of the first embodiment. After process S907, the process proceeds to process S908.

  In step S908, it is determined whether the calculation result of the battery drop voltage ΔV in step S907 is the latest three times. If there are three calculation results, the process proceeds to step S909. When there is no calculation result for three times, the process proceeds to process S901.

  In process S909, the latest three times of the calculation results of the battery drop voltage ΔV in process S907 are averaged. Thereafter, the process proceeds to process S910.

  The processing from processing S910 to processing S912 is the same as the processing from processing S18 to processing S20 in FIG. 6 of the first embodiment.

  According to the third embodiment of the present invention, the influence of the error on the measurement result of the battery voltage due to the periodic change of the external environment can be suppressed by averaging the measurement results of a plurality of times in this cycle. The effect of deriving the remaining capacity of the battery with higher accuracy than in the first and second embodiments can be obtained.

  In the third embodiment, an A / D converter is used as an instrument for measuring the voltage of the battery, but even when other instruments are used, the measurement results are due to periodic changes in the external environment. If it is affected, the same effect can be obtained.

11 Center server 12 Internet network 13 Gateway 14 Base unit radios 15A, 15B, 15C, 15D, 15E Slave unit radio units 16A, 16B, 16C, 16D, 16E Meter 21 Antenna 22 Radio unit 23 CPU
24 Meter interface 25 Battery 221 Receiver 222 Transmitter 231 ROM
232 RAM
233 A / D converter

Claims (9)

In a communication device including a communication unit that performs communication with a peripheral device, and a battery that supplies power to the communication unit,
The battery depends on the remaining battery capacity that is the remaining capacity of the battery and the communication time from the start to the end of the communication,
The voltage difference between the voltage at the start of communication and the voltage at the end of the communication changes,
A voltage difference measuring unit for measuring the voltage difference of the battery;
A time measuring unit for measuring the communication time;
A relationship storage unit that stores a relationship between the communication time of the communication unit, the remaining battery capacity, and the voltage difference of the battery;
Based on the relationship stored in the relationship storage unit,
A battery remaining capacity deriving unit for deriving the battery remaining capacity using the voltage difference of the battery measured by the voltage difference measuring unit and the time measured by the time measuring unit;
A communication apparatus, further comprising:   The communication device according to claim 1, wherein the communication unit is a wireless unit that performs wireless communication with a peripheral device. The communication device according to claim 1, further comprising an alarm unit that issues an alarm to the outside based on the remaining battery capacity derived by the remaining battery capacity deriving unit. The communication device according to claim 3.
A threshold storage unit for storing a threshold of the remaining battery capacity;
A threshold determination unit that determines that the battery remaining capacity derived by the battery remaining capacity deriving unit is lower than the threshold;
The communication device further comprises: the alarm unit issues an alarm based on the determination by the threshold determination unit. A communication unit for communicating with peripheral devices;
A battery remaining capacity derivation method executed in a communication device comprising a battery for supplying power to the communication unit,
A voltage difference measuring step for measuring a voltage difference between the voltage at the start of the communication and the voltage at the end of the communication in the battery;
A time measurement step of measuring a communication time from the start to the end of the communication;
Based on the characteristics of the battery in which the voltage difference changes depending on the battery remaining capacity that is the remaining capacity of the battery and the communication time,
A battery remaining capacity deriving step for deriving the battery remaining capacity from the voltage difference of the battery measured in the voltage difference measuring step and the communication time measured in the time measuring step;
A battery remaining capacity deriving method characterized by comprising: A cycle determination step for determining cycle circulation;
A periodic circulation notification step of notifying the circulation of the cycle determined in the cycle determination step;
A periodic communication step of performing the communication by notification from the periodic circulation notification step;
A periodic battery remaining capacity deriving step of performing the battery remaining capacity deriving step by notification from the periodic circulation notification step;
In a period when there is no notification from the periodic circulation notification step,
A low power operation step of suppressing power consumption of the battery without performing the communication step and the battery remaining capacity derivation step;
The battery remaining capacity derivation method according to claim 5, wherein: An average battery remaining capacity calculating step for calculating an average value of the past battery remaining capacity derived in the periodic battery remaining capacity deriving step;
The battery remaining capacity derivation method according to claim 6, further comprising: The battery remaining capacity deriving method according to any one of claims 5 to 7,
In order to have the battery perform a constant discharge over the communication time,
A continuous reception step of continuously receiving signals transmitted from peripheral devices in the communication only during the communication time;
The battery remaining capacity derivation method further comprising: The battery remaining capacity deriving method according to any one of claims 5 to 7,
In order to have the battery perform a constant discharge over the communication time,
A continuous transmission step of continuously transmitting a signal to the peripheral device during the communication time in the communication;
The battery remaining capacity derivation method further comprising:

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