Terminal device and wireless communication system

0001The present invention relates to terminals and wireless communication systems.

0002The wireless communication system includes a parent radio and a terminal capable of communicating with the parent radio. Specific examples of the wireless communication system include the following.

0003For example, it is a wireless communication system that collects biological information such as the pulse of a subject. In this wireless communication system, the terminal is attached to the subject and collects the biological information of the subject. Then, the terminal wirelessly transmits the biological information to the parent radio.

0004Further, for example, there is a wireless communication system in which a building manager collects power information of each load circuit in a distribution board. The terminal is installed in the distribution board and collects the power supplied to each load circuit as power information. Then, the terminal wirelessly transmits the power information to the parent radio.

0005In these wireless communication systems, the terminal and the parent radio are paired at the time of initial setting so that the terminal does not transmit information to an unrelated parent radio. Hereinafter, this pairing is referred to as registration. Once registration is complete, information can be communicated between the terminal and the parent radio.

0006Conventional techniques similar to such wireless communication systems are listed in the following patent documents.

<p num="0007"><patcit num="1"><text>Japanese Unexamined Patent Publication No. 2004-096429</text></patcit><patcit num="2"><text>Japanese Unexamined Patent Publication No. 2009-105667</text></patcit></p>

0008The terminal can communicate with the parent radio. The terminal is equipped with a control circuit. The control circuit has at least two operation modes, a normal mode for outputting start-up information regarding the start-up of the terminal and a registration mode for outputting registration information regarding registration between the terminal and the parent radio. The control circuit shifts the operation mode to the registration mode based on the timing of multiple startups of the terminal.<u style="single">Then send the registration information to the parent radio.</u>

0009The wireless communication system includes a parent radio and a terminal capable of communicating with the parent radio. The terminal has a control circuit. The control circuit has at least two operation modes, a normal mode for outputting start-up information regarding the start-up of the terminal and a registration mode for outputting registration information regarding registration between the terminal and the parent radio. The control circuit shifts the operation mode to the registration mode based on the timing of starting the terminal a plurality of times. The registration information is transmitted from the terminal to the parent radio, received by the parent radio, and the terminal and the parent radio are registered.

0010The terminal can shift to the registration mode by using the same operation and mechanism as that of the operation in the normal mode.

0011<figref num="1">FIG. 1 is a schematic view showing the overall configuration of the wireless communication system according to the first embodiment.</figref><figref num="2">FIG. 2 is a block diagram showing an electrical configuration of the terminal according to the first embodiment.</figref><figref num="3">FIG. 3 is a block diagram showing an electrical configuration of the parent radio according to the first embodiment.</figref><figref num="4">FIG. 4 is a sequence diagram showing a registration method of the wireless communication system according to the first embodiment.</figref><figref num="5">FIG. 5 is a timing diagram when the control circuit of the terminal in the first embodiment is shifted to the registration mode.</figref><figref num="6">FIG. 6 is a block diagram showing an electrical configuration of the terminal in the second embodiment.</figref><figref num="7">FIG. 7 is a block diagram showing an electrical configuration of the parent radio according to the second embodiment.</figref><figref num="8">FIG. 8 is a sequence diagram showing a registration method of the wireless communication system according to the second embodiment.</figref><figref num="9">FIG. 9 is a block diagram showing an electrical configuration of the terminal according to the third embodiment.</figref><figref num="10">FIG. 10 is a block diagram showing an electrical configuration of another example terminal in the third embodiment.</figref><figref num="11">FIG. 11 is a timing diagram when the control circuit of the terminal in the third embodiment is shifted to the registration mode.</figref>

0012Hereinafter, embodiments of the present invention will be described with reference to the drawings as appropriate. The following embodiments are examples of the present invention and do not limit the scope of the present invention.

0013(1. Embodiment 1) (1-1. Overview) FIG. 1 schematically shows the entire wireless communication system of the first embodiment. This wireless communication system is used to detect the opening and closing of a window, confirm that the window has been forgotten to be closed, or confirm the presence or absence of an intruder through the window. This wireless communication system is an ultra-low power consumption type, so-called energy harvesting radio.

0014The wireless communication system of the first embodiment includes a parent radio 300 and a terminal 100. The terminal 100 is mounted inside the window frame 50. The parent radio 300 is installed at a position away from the terminal 100. The user 51 of this wireless communication system is, for example, a window contractor, a resident of a room, or the like. By the operation of opening the window 52 of the user 51 and the operation of closing the window 52, the terminal 100 generates electricity and notifies the parent radio 300 of the opening / closing of the window 52. The parent radio 300 and the terminal 100 are registered, that is, paired at the time of initial setting. Once registered, the parent radio 300 and the terminal 100 are in a registration relationship. Then, information can be communicated between the two. When there are a plurality of target windows, a plurality of terminal 100s may be prepared and each terminal 100 may be arranged in each window. The parent radio 300 has a registration relationship with each terminal 100.

0015Here, a registration method different from that of the first embodiment will be described for comparison with the first embodiment. In this method, the terminal is provided with a switch for shifting the operation mode of the terminal to the registration mode. When the user turns on the switch, the terminal transmits registration information such as the terminal identifier and the encryption key to the parent radio. If the parent radio receives and stores the registration information, the registration is completed.

0016In addition, other registration methods will be described. In this method, the user opens and closes the window and activates the terminal in the normal operation mode. Then, the terminal transmits the activation information such as the identifier of the terminal and the encrypted data related to the opening / closing of the window to the parent radio. The parent radio queries the server database for the encryption key of the terminal based on the identifier. Then, if the parent radio stores the encryption key obtained from the database, the registration is completed.

0017The first registration method requires the user to press a switch on the terminal. Therefore, it becomes difficult to incorporate the terminal into equipment such as a window frame. Further, since the terminal is provided with a mechanism different from the mechanism used in the normal mode, the terminal may become large. In the second registration method, the parent radio needs to inquire the registration information from the database. Therefore, the wireless communication system cannot complete the registration work by itself. In addition, it may take some time to query the database. In addition, a lot of labor may be required for system construction and data management and operation.

0018With respect to these registration methods, in the wireless communication system of the first embodiment, the user 51 opens and closes the window 52 a plurality of times at a predetermined timing. When the terminal 100 determines that the timing matches a predetermined timing, the terminal 100 shifts the operation mode to the registration mode. Then, the terminal 100 in the registration mode communicates with the parent radio 300 regarding registration.

0019As described above, the terminal 100 of the first embodiment can shift to the registration mode by using the opening and closing of the window 52. That is, the terminal 100 can shift to the registration mode by using the same operation and mechanism as those operating in the normal mode. In addition, the parent radio 300 does not need to inquire the registration information from the database.

0020(1-2. Electrical configuration) (1-2-1. Electrical configuration of the terminal) Hereinafter, the electrical configuration of the terminal 100 of the first embodiment will be described with reference to FIG. FIG. 2 is a block diagram showing the configuration of the terminal 100. The terminal 100 includes a power generation circuit 10, a voltage conversion circuit 11, a control circuit 12, a determination circuit 13, a transmission circuit 14, and an antenna 15.

0021The power generation circuit 10 is a circuit that generates power using energy generated by opening and closing the window 52. The electric power Vbat obtained in the power generation circuit 10 is supplied to the control circuit 12 and the transmission circuit 14 of the terminal 100. The power Vbat is about 0 to 10V. The electric power Vbat is rectified by the diode D11, temporarily stored in the charge charging capacitor C11, and input to the voltage conversion circuit 11.

0022The voltage conversion circuit 11 is a circuit that converts the voltage of the electric power Vbat. The voltage conversion circuit 11 has an under voltage lock out (UVLO) function to prevent malfunction. In the first embodiment, the threshold UVLO voltage is set to 1.85V. The voltage exceeding 1.85V is converted to 1.8V by the voltage conversion circuit 11 and supplied to the control circuit 12 as the power supply voltage VDD. Since the electric power Vbat is generated by the power generation circuit 10 each time the window 52 is opened and closed, the waveform of the power supply voltage VDD is a pulse waveform.

0023The control circuit 12 outputs various signals when the power supply voltage VDD is input. The operation mode in which the control circuit 12 is set is at least two, a normal mode and a registration mode. In the normal mode, the control circuit 12 outputs start-up information regarding the start-up of the terminal 100, for example, an identifier of the terminal 100 and data regarding the opening / closing of the window 52, when the power supply voltage VDD is input. The data regarding the opening and closing of the window 52 is encrypted from the viewpoint of security. Hereinafter, the encrypted data will be referred to as encrypted data. On the other hand, in the registration mode, when the power supply voltage VDD is input, the control circuit 12 decrypts the registration information regarding the registration between the terminal 100 and the parent radio 300, for example, the identifier of the terminal 100 and the encrypted data. Encrypt key and output. The control circuit 12 has a non-volatile memory 121 and a central processing unit 122. The identifier and the encryption key are stored in the non-volatile memory 121. The central processing unit 122 performs various numerical calculations, information processing, circuit control, and the like.

0024The determination circuit 13 is a circuit for determining whether or not a predetermined time has elapsed from the previous activation of the terminal 100 to the next activation. Then, it is used to determine whether or not to shift the operation mode of the control circuit 12 from the normal mode to the registration mode. The determination circuit 13 is a time constant circuit having a diode D21, a resistor R21, and a capacitor C21. The capacitance of the capacitor C21 of the first embodiment is 1 μF, and the resistance value of the resistor R21 is 1 MΩ. Therefore, the time constant τ of the determination circuit 13 is set to 1 second. The voltage input from the output port of the control circuit 12 to the determination circuit 13 decreases according to the time constant τ. The output voltage that drops in the determination circuit 13 can be read by the input port of the control circuit 12. Then, according to the read output value of the determination circuit 13, the interval from the previous start of the terminal 100 to the next start, that is, the user 51 opens and closes the window 52 last time, and then opens and closes the window 52. You can see the interval to. The operation when the control circuit 12 shifts from the normal mode to the registration mode based on the output of the determination circuit 13 will be described in detail in the item of the registration method described later.

0025The transmission circuit 14 is a circuit that transmits the signal output from the control circuit 12 to the parent radio 300 via the antenna 15. The transmission circuit 14 transmits signals such as start-up information and registration information using the electric power obtained by the power generation circuit 10.

0026(1-2-2. Electrical configuration of parent radio) Hereinafter, the configuration of the parent radio 300 of the first embodiment will be described with reference to FIG. The parent radio 300 includes a receiving circuit 30, an antenna 31, a control circuit 32, and a power supply circuit 33. The control circuit 32 includes a non-volatile memory 321 and a central processing unit 322.

0027The receiving circuit 30 is a circuit that receives a transmission signal from the terminal 100 via the antenna 31.

0028The control circuit 32 is a circuit that uses the central processing unit 322 to decrypt the encrypted data received by the receiving circuit 30 and to register the encrypted data with the terminal 100. The non-volatile memory 321 stores the identifier of the terminal 100 and the encryption key.

0029The power supply circuit 33 is a circuit that supplies power to the receiving circuit 30, the control circuit 32, and the like. The power supply circuit 33 is connected to an external power supply.

0030(1-3. Registration method) Hereinafter, a method of registering the terminal 100 and the parent radio 300 will be described with reference to FIGS. 4 and 5. FIG. 4 is a sequence diagram showing a registration method. FIG. 5 is a timing diagram when the control circuit 12 of the terminal 100 shifts to the registration mode. Operators A and B shown in FIG. 4 are window contractors and the like on which the terminal 100 and the parent radio 300 are installed. Operator A and operator B may be different persons or the same person.

0031As shown in FIG. 4, the terminal 100 is in intermittent operation. In the first embodiment, electric power is supplied to the terminal 100 by the power generation of the terminal 100 itself only when the window 52 is opened and closed. Then, the terminal 100 starts at the same time as the power is supplied, and operates only for a certain period of time after the start-up, that is, a certain time after the window 52 is opened and closed. Then, after the terminal 100 has been operated for a certain period of time, the terminal 100 is stopped because the power is used up (S101).

0032On the other hand, since the parent radio 300 is connected to an external power source, it is always in operation. The operation mode of the parent radio 300 is usually a normal mode in which startup information is received from the terminal 100 (S301). When the operator B operates the parent radio 300 and issues a command to shift to the registration mode, the parent radio 300 starts registration (S302).

0033Then, when the terminal 100 is in the stopped state (S101), the operator A opens or closes the window 52. Then, the terminal 100 generates electricity and starts, that is, wakes (S102). When the terminal 100 starts up, it determines whether or not the start-up timing matches a predetermined timing pattern for shifting to the registration mode. If it is determined that they do not match (S103), the operation mode is shifted to the normal mode (S104). In addition, the start timing information is stored in the non-volatile memory 121 of the terminal 100. After that, the activation information, the own identifier and the encrypted data regarding the opening and closing of the window 52, are transmitted to the parent radio 300. In the first embodiment, the identifier and the encrypted data are transmitted a plurality of times per activation in order to increase the certainty of transmission. It should be noted that the transmission may be performed once for each activation. Then, when the transmission is completed and the power is used up, the stop state is resumed (S105).

0034Here, when the operation mode of the control circuit 12 of the terminal 100 is changed from the normal mode to the registration mode, the operator A opens and closes the window 52 a plurality of times in a predetermined timing pattern. In the first embodiment, the window 52 is opened and closed five times, for example, "opening", "closing", "opening", "closing", and "opening" the window 52. Then, the interval between the second and third opening and closing is set to a long timing of t2 seconds or more, and the other intervals are set to a short timing of less than t1 seconds. Then, the terminal 100 starts up with a timing pattern corresponding to the timing pattern of opening and closing the window 52 five times. Then, the terminal 100 is activated every time the window 52 is opened and closed, and the combination (S106) of the above steps S102 to S105 is repeated (S107). In addition, information on each startup timing is stored in the non-volatile memory 121.

0035In the first embodiment, step S102 is the first start-up, step S107 is a step associated with the second to fourth start-ups, and step S108 is the fifth start-up.

0036Then, in step S109, when it is determined that the timing pattern of five activations stored in the non-volatile memory 121 matches the predetermined timing pattern, the control circuit 12 of the terminal 100 shifts to the registration mode (S110). ). The determination of this timing pattern will be described later with reference to FIG.

0037Then, in the registration mode, the terminal 100 outputs registration information regarding registration with the parent radio 300, that is, an identifier and an encryption key, and transmits the information to the parent radio 300. When the terminal 100 finishes transmitting the identifier and the encryption key, the terminal 100 resets the timing pattern stored in the non-volatile memory 121. Then, the terminal 100 is stopped again (S112).

0038On the other hand, when the parent radio 300 receives the identifier and the encryption key which are the registration information from the terminal 100 in the state where the registration is started, the parent radio 300 stores the identifier and the encryption key in its own non-volatile memory 321. This is the registration on the parent radio 300 side (S304).

0039Finally, the operator A confirms whether the registration has been performed correctly. Operator A opens or closes the window 52 once, and restarts the terminal 100 (S113). The terminal 100 determines the activation timing pattern, and when it is determined that the timing pattern does not match the predetermined timing pattern (S114), the terminal 100 then shifts to the normal mode (S115). Then, the activation information, that is, the identifier and the encrypted data are transmitted to the parent radio 300, and then the stop state is set (S116).

0040The parent radio 300 receives the identifier and the encrypted data from the terminal 100. If the parent radio 300 can correctly decrypt the received encrypted data, the registration between the terminal 100 and the parent radio 300 is completed (S305). When the registration is completed, the parent radio 300 outputs a registration completion notification to the operator B and returns to the normal mode (S306). The registration completion notification notifies the operator B of the completion of registration. The registration completion notification may be, for example, a signal such as sound or light, or an email may be sent to a predetermined address.

0041The wireless communication system is registered by the communication between the terminal 100 and the parent radio 300 as described above. Once the registration of both is completed, communication between the terminal 100 and the parent radio 300 becomes possible. That is, every time the user 51 opens and closes the window 52, the terminal 100 transmits its own activation information to the parent radio 300, and the parent radio 300 can receive and decode it. The user 51 can obtain information regarding the opening and closing of the window 52 by the notification from the parent radio 300 or the access to the parent radio 300.

0042Hereinafter, a method of determining whether or not the opening / closing timing pattern of the window 52 matches a predetermined timing pattern will be described in detail with reference to FIG.

0043FIG. 5 is a timing diagram of the control circuit 12 when the operator A opens and closes the window 52 five times as described above. As mentioned above, the interval between the second and third opening and closing is t2 seconds or more, and the other intervals are less than t1 seconds.

0044Each time the window 52 is opened or closed, a pulse voltage of power supply voltage VDD is supplied to the control circuit 12. Then, the pulse voltage corresponding to the power supply voltage VDD is supplied to the determination circuit 13 via the output port. The output voltage from the determination circuit 13 is input to the input port of the control circuit 12. A voltage that has dropped according to the time constant τ of the determination circuit 13 described above is input to the input port. The control circuit 12 compares the voltage value of the input port with a predetermined reference value when the waveform of the power supply voltage VDD rises. The reference value is a predetermined value, and there are two values, high (H) and low (L). By comparing the voltage value at the input port with the two reference values, the interval from the previous start of the terminal 100 to the next start can be found. In the first embodiment, if the voltage value read by the input port is higher than the reference value (H), the control circuit 12 determines that the interval from the previous start to the next start is shorter than t1 second, and " 1 "is output. On the other hand, if the voltage value read by the input port is lower than the reference value (L), the control circuit 12 determines that the interval from the previous start to the next start is t2 seconds or more, and outputs "0". .. Therefore, in the case of the start timing of the first embodiment, the control circuit 12 outputs "0", "1", "0", "1", and "1".

0045This output pattern is compared with the output pattern stored in advance in the non-volatile memory 121, and if they match, the control circuit 12 shifts the operation mode to the registration mode. If they do not match, the operation mode is left as the normal mode. As described above, the control circuit 12 of the terminal 100 shifts from the normal mode to the registration mode based on the timing of starting the terminal 100 a plurality of times.

0046(1-4. Effects, etc.) In the first embodiment, the terminal 100 can be shifted to the registration mode by opening and closing the window 52 in the same manner as operating the terminal 100 in the normal mode. Therefore, the terminal 100 does not require a special mechanism for switching the operation mode, such as a switch for shifting to the registration mode. Furthermore, the user does not need to press the switch to shift to the registration mode. Therefore, the user can easily shift the terminal 100 to the registration mode even in the energy harvesting radio which is often built in the equipment or installed in a place that is hard to reach. In addition, the parent radio 300 does not need to inquire the registration information from the database. Therefore, the wireless communication system can self-complete the registration operation. Furthermore, since there is no need to inquire about the database, the wireless communication system can reduce the time required for registration. The system itself can also be simplified. Then, the labor required for system construction, data management and operation can be reduced.

0047Although the terminal 100 of the first embodiment is suitable for the terminal 100 including the power generation circuit 10, it can also be applied to the terminal 100 which does not have the power generation circuit 10 and uses a battery.

0048Further, in the first embodiment, the opening / closing of the window 52 at one time refers to either opening or closing the window 52, but may also refer to opening and closing. ..

0049Further, in the first embodiment, the "plurality" of the "timing of a plurality of activations" refers to five times, but the number of times may be a plurality of times and is not limited to five times. However, three times or more is more preferable in order to reduce malfunction.

0050Further, in the first embodiment, the normal mode and the registration mode are mentioned as the operation modes of the control circuit 12, but other operation modes may be set. For example, it may be possible to set a hibernation mode in which no signal is output even when the terminal 100 is activated. Then, as shown in FIG. 4, the terminal 100 directly shifts from the normal mode to the registration mode in the process S110. For example, after determining that the start pattern matches in the process S109, another operation such as a pause mode is performed. The mode may be sandwiched and the mode may be shifted from the hibernate mode to the registration mode.

0051Further, in the first embodiment, after the registration of the process S304, the terminal 100 is started again in the process S113 to confirm the registration, but the operation may be omitted. That is, the registration can be completed after the registration of the process S304 without confirming the registration.

0052Further, in the first embodiment, the terminal 100 is installed inside the window frame 50, but the installation location is not limited to this, and may be the surface of the window frame 50, the inside of the glass window, or the like.

0053In the first embodiment, the wireless communication system is used for detecting the opening / closing of the window 52, but it can also be used for other purposes. For example, it can be used to detect whether or not lighting, air conditioning equipment, electrical appliances, etc. are in operation, whether or not a door is opened or closed, and whether or not a window or door is locked. Then, the terminal 100 may be arranged on a switch, a door, a key lever, a door knob, or the like according to the application of the wireless communication system. The terminal 100 may be activated by generating electricity by switching ON / OFF of a switch, opening / closing a door, and rotating or displacementing a lever or a door knob. In addition, this wireless communication system can also be used for a wireless communication system that collects biological information such as pulse and blink of humans and animals. In this case, the terminal 100 is arranged near a blood vessel of a human or an animal, an eyelid, or the like. Then, the terminal 100 generates electricity by the movement of the living body and starts up.

0054(2. Embodiment 2) Hereinafter, the wireless communication system of the second embodiment will be described with reference to FIGS. 6 to 8. The wireless communication system of the second embodiment and the first embodiment have the same operation until the terminal 110 shifts to the registration mode. Then, after the terminal 110 shifts to the registration mode, the registration method between the terminal 110 and the parent radio 310 is different. Here, for the sake of simplification of the description, the same reference numerals are used for the configurations common to the second embodiment and the first embodiment.

0055(2-1. Electrical configuration) (2-1-1. Electrical configuration of the terminal) FIG. 6 shows the electrical configuration of the terminal 110 of the second embodiment. The terminal 110 includes a receiving circuit 16. Further, the terminal 110 includes a power generation circuit 10, a voltage conversion circuit 11, a control circuit 12, a determination circuit 13, a transmission circuit 14, and an antenna 15 as in the terminal 100 of the first embodiment. There is.

0056The receiving circuit 16 is a circuit that receives a signal from the parent radio 310 via the antenna 15. In the second embodiment, the signal from the parent radio 310 refers to the identifier of the terminal 110 and the encryption key.

0057(2-1-2. Electrical configuration of parent radio) FIG. 7 shows the electrical configuration of the parent radio 310 of the second embodiment. The parent radio 310 includes a transmission circuit 34. Further, the parent radio 310 includes a receiving circuit 30, an antenna 31, a control circuit 32, and a power supply circuit 33, similarly to the parent radio 300 of the first embodiment.

0058The transmission circuit 34 is a circuit for transmitting a signal to the terminal 110 via the antenna 31.

0059(2-2. Registration method) FIG. 8 is a sequence diagram showing a registration method of the wireless communication system according to the second embodiment.

0060The terminal 110 shifts to the registration mode in step S110 as in the first embodiment. Then, in the second embodiment, when the terminal 110 shifts to the registration mode, the terminal 110 outputs the identifier of the terminal 110 and the registration request signal as registration information, and transmits them to the parent radio 310. The registration request signal is a signal requesting the parent radio 310 to transmit an encryption key. The encryption key is used to encrypt data related to opening and closing windows. In the second embodiment, the encryption key sent from the parent radio 310 is different each time it is registered.

0061When the parent radio 310 receives the registration request signal from the terminal 110 in the state where registration has been started (S302), the parent radio 310 transmits the identifier of the terminal 110 and the encryption key to the terminal 110 (S303).

0062The terminal 110 stores the encryption key sent from the parent radio 310 in the non-volatile memory 121 (S111). If the encryption key previously sent from the parent radio 310 is already stored, update it with a new encryption key. By storing the new encryption key in the non-volatile memory 121, the registration on the terminal 110 side is completed. Then, the terminal 110 resets the timing pattern stored in the non-volatile memory 121 so far, and is in the stop state again (S112).

0063Finally, as in the first embodiment, the operator A confirms whether the registration has been performed correctly. When the operator A opens or closes the window 52 once, the terminal 110 is activated (S113). Then, it is determined whether or not the activation timing pattern matches the predetermined pattern, and if it is determined that the pattern does not match (S114), the operation mode is shifted to the normal mode (S115). The terminal 110 transmits the activation information, that is, the identifier and the encrypted data to the parent radio 310 in the normal mode. This encrypted data is encrypted with the new encryption key registered in step S111. The parent radio 310 receives the activation information and duplicates the received encrypted data with the new encryption key described above. If the parent radio 310 can correctly duplicate the encrypted data, the registration between the terminal 110 and the parent radio 310 is completed (S305). Then, the parent radio 310 sends a registration completion notification to the operator B, and returns to the normal mode (S306).

0064Once the registration between the terminal 110 and the parent radio 310 is completed, the next time the user 51 opens and closes the window 52, the terminal 110 will self-encrypt the data encrypted with the new encryption key described above. It is transmitted to the parent radio 310 together with the identifier of. Then, the parent radio 310 can decrypt the encrypted data by using the encryption key and notify the user 51 of the information.

0065(2-3. Effects, etc.) In the second embodiment, since the encryption key is transmitted from the parent radio 310, the encryption key can be updated every time. Therefore, the accuracy of security can be remarkably improved. For example, it is useful when the resident of the room changes or when only the parent radio 310 is changed to a new model.

0066Further, if the terminal 110 can secure a sufficient amount of power generation, the so-called public key method can also be used. In this case, the parent radio 310 transmits the public key as the encryption key in step S303. The terminal 110 stores the public key in step S111, and in step S115, transmits the encrypted data encrypted with the public key as activation information to the parent radio 310. On the other hand, the parent radio 310 decrypts the encrypted data with the private key stored in the non-volatile memory 321 only by the parent radio 310. By using this public key method, the possibility that the encrypted data can be read by a third party can be further reduced.

0067In the second embodiment, the parent radio 310 transmits a different encryption key to the terminal 110 each time, but for example, even if an encryption key randomly selected from a plurality of encryption keys is transmitted. Good. Further, instead of changing the encryption key every time, the same encryption key may be changed every time the same encryption key is used a plurality of times. Strengthen security by making the encryption key sent from the parent radio 310 to the terminal 110 different from the encryption key sent from the parent radio 310 before this encryption key was sent. Can be done. Registration is possible even if the same encryption key is used each time.

0068Further, in the second embodiment, the parent radio 310 automatically sets the encryption key, but the operator B may arbitrarily set the encryption key.

0069Further, also in the second embodiment, the registration is confirmed before the registration of the step 305 is completed, but the operation can be omitted.

0070Further, also in the second embodiment, similarly to the first embodiment, the terminal 110 can be shifted to the registration mode by the operation of opening and closing the window 52 in the same manner as operating the terminal 110 in the normal mode. Further, the parent radio 310 does not need to make an inquiry to the database.

0071(2-4. Modification example) The transmission power at which the terminal 110 transmits the registration information to the parent radio 310 and the transmission power at which the parent radio 310 transmits the encryption key to the terminal 110 may be the same, but the terminal 110 transmits the registration information. The transmission power for transmitting the encryption key by the parent radio 310 may be larger than the power for transmission. Here, since the parent radio 310 is connected to an external power source, there is a margin in the amount of power that can be used. Therefore, increasing the transmission power of the parent radio 310 is easier than increasing the transmission power of the terminal 110. Even if the antenna gain of the terminal 110 is smaller than the antenna gain of the parent radio 310, the terminal 110 can more accurately perform the parent radio by increasing the transmission power for transmitting the encryption key by the parent radio 310. The signal from the machine 310 can be received.

0072Further, the communication frequency used when the terminal 110 transmits the registration information to the master radio 310 and the communication frequency used when the master radio 310 transmits the encryption key to the terminal 110 may be changed. For example, a case where a wireless communication system is used in Japan will be described. When the terminal 110 transmits registration information, it uses a frequency band (928.15MHz to 929.65MHz) where the maximum power permitted by law is 1mW, which is relatively small. On the other hand, when the parent radio 310 transmits the encryption key to the terminal 110, the maximum allowable power is 20 mW, which is a relatively large frequency band (923.6 MHz to 928.0 MHz). As a result, the parent radio 310 can transmit with a larger transmission power.

0073The description of other configurations and effects similar to those of the first embodiment will be omitted.

0074(3. Embodiment 3) Hereinafter, the wireless communication system of the third embodiment will be described with reference to FIGS. 9 to 11. The electrical configuration of the terminal 120 is partially different between the third embodiment and the first embodiment. Then, in the terminal 120 of the third embodiment, the electric power equal to or lower than the UVLO voltage, which was discarded in the first embodiment, is supplied to the determination circuit 13. The electrical configurations of the parent radio 300 of the third embodiment and the first embodiment are the same. Here, for the sake of simplification of the description, the same reference numerals are used for the configurations common to the third embodiment and the first embodiment.

0075(3-1. Electrical configuration of the terminal) FIG. 9 shows the electrical configuration of the terminal 120 of the third embodiment. The terminal 120 includes a voltage detection circuit 17 and a transistor Tr11 as a switch. Further, the terminal 120 includes a power generation circuit 10, a voltage conversion circuit 11, a control circuit 12, a determination circuit 13, a transmission circuit 14, and an antenna 15 as in the terminal 100 of the first embodiment. There is.

0076The voltage detection circuit 17 is a circuit that changes the output impedance when the voltage falls below a specified voltage. In the third embodiment, a voltage exceeding the UVLO voltage, that is, a voltage larger than 1.85V has a high impedance, and a voltage lower than the UVLO voltage has a low impedance.

0077The switch is the transistor Tr11 of FIG. 10 in the third embodiment. The transistor Tr11 is used to input a charge equal to or lower than the UVLO voltage to the determination circuit 13. The base electrode of the transistor Tr11 is connected to the output side of the voltage detection circuit 17. The transistor Tr11 is turned on when the output impedance of the voltage detection circuit 17 is switched to low impedance. On the other hand, the transistor Tr11 is turned off when the output impedance of the voltage detection circuit 17 is switched to high impedance. The transistor Tr11 is arranged between the capacitor C11 for storing the electric power obtained by the power generation circuit 10 and the capacitor C21 constituting the determination circuit 13. A resistor R31 is arranged between the input side of the voltage conversion circuit 11 and the base electrode of the transistor Tr11 as a bias resistance of the transistor Tr11. As a result, the base voltage of the transistor Tr11 can be stabilized. Then, the voltage can be supplied to the transistor Tr11 so that the transistor Tr11 can be turned on and off as a switch by changing the output impedance of the voltage detection circuit 17 between low and high.

0078Further, in the third embodiment, the delay element 18 is arranged between the capacitor C11 and the transistor Tr11. The delay element 18 is, for example, a resistor, a coil, a semiconductor element, or the like. Here, immediately after power generation, the transistor Tr11 may be turned on due to a slight time delay for the voltage detection circuit 17 to detect the voltage, and an electric charge may be supplied to the capacitor C21 of the determination circuit 13. On the other hand, by arranging the delay element 18 as in the third embodiment, it is possible to suppress the supply of electric charge to the determination circuit 13 immediately after power generation. Note that FIG. 10 shows the electrical configuration of the terminal 130 of another example of the third embodiment. As shown in FIG. 10, the delay element 18 may be arranged between the transistor Tr 11 and the capacitor 21. The position of the delay element 18 is different between the terminal 130 and the terminal 120, but the other configurations are the same.

0079The voltage from the power generation circuit 10 is supplied to the determination circuit 13 of the third embodiment without going through the control circuit 12. That is, of the electric power obtained in the power generation circuit 10, the electric power supplied to the determination circuit 13 is supplied to the determination circuit 13 without going through the control circuit 12. The output of the determination circuit 13 can be read by the input port of the control circuit 12 as in the first embodiment.

0080(3-2. Operation of the terminal at the time of registration) FIG. 11 is a timing diagram when the terminal 120 shifts to the registration mode.

0081Each time the window 52 is opened or closed, the power generation circuit 10 generates electric power Vbat. Due to the UVLO function of the voltage conversion circuit 11, low voltage of 1.85V or less is cut off, and the power supply voltage VDD becomes a pulse waveform as shown in FIG. The output impedance of the voltage detection circuit 17 becomes high impedance when it exceeds 1.85V and low impedance when it exceeds 1.85V. When the output impedance of the voltage detection circuit 17 is high impedance, the transistor Tr11 is in the OFF state (OFF), and when the output impedance is low impedance, the transistor Tr11 is in the ON state (ON). When the transistor Tr11 is in the ON state, a voltage is supplied to the determination circuit 13. Then, the voltage dropped according to the time constant τ is read at the input port.

0082Similar to the control circuit 12 of the first embodiment, the control circuit 12 reads the output of the determination circuit 13 when the waveform of the power supply voltage VDD rises. Then, the control circuit 12 outputs "1" when the read voltage value is a voltage value equal to or higher than a predetermined high level (H). On the other hand, if the read voltage value is a voltage value equal to or lower than a predetermined low level (L), "0" is output.

0083Then, when the output patterns for a plurality of times match a predetermined output pattern, the control circuit 12 switches the operation mode to the registration mode. As described above, the control circuit 12 of the terminal 120 shifts from the normal mode to the registration mode after the start-up based on the timing of the start-up a plurality of times.

0084(3-3. Effects, etc.) In the third embodiment, the originally discarded electric charge can be applied to the determination circuit 13, and the energy can be effectively utilized. Then, sufficient power can be supplied to the control circuit 12 and the transmission circuit 14.

0085Further, by providing the delay element 18, the output value of the determination circuit 13 can be stabilized, and the output of the determination circuit 13 can be read with high accuracy by the control circuit 12.

0086The description of other configurations and effects similar to those of the first embodiment will be omitted.

0087The terminals of the above-described first to third embodiments can shift to the registration mode by using the same operation and mechanism as those of the normal mode. Therefore, it can be applied to a wireless communication system, for example, a so-called energy harvest radio.

0088100,110,120,130 terminal 300,310 Parent radio 50 window frame 51 users 52 windows 10 Power generation circuit 11 Voltage conversion circuit 12 Control circuit 121 Non-volatile memory 122 Central processing unit 13 Judgment circuit 14 Transmission circuit 15 antenna 16 Receiving circuit 17 Voltage detection circuit 30 Receiving circuit 31 antenna 32 control circuit 321 Non-volatile memory 322 Central processing unit 33 Power circuit 34 Transmission circuit