Wireless device

Abstract

To provide a radio device capable of realizing an ESD countermeasure when an external device is attached and preventing deterioration of a signal waveform.SOLUTION: A radio device (GM) comprises an electronic circuit board (20) having a communication unit (16) and a control unit (10) for wirelessly transmitting a measurement value of a fluid physical quantity to an external device, and an external antenna (17) connected to a signal line (21), wherein the radio device (GM) is provided with a changeover switch (23) which is connected between the signal line (21) and a ground unit (24) and switches between a conductive state and a non-conductive state, and when an operator connects the external antenna (17) to the signal line (21) in an assembly work of the radio device (GM), the changeover switch (23) becomes conductive, and the signal line (21) and the ground unit (24) are electrically connected to each other. When a predetermined action is performed by an operator after the external antenna 17 is connected to the signal line 21, the changeover switch 23 is brought into a non-conductive state to electrically disconnect the signal line 21 from the grounding part 24.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to wireless devices. [Background technology]

[0002] In recent years, automatic meter reading systems have been introduced for gas meters and the like. Such automatic meter reading systems use, for example, gas meters with wireless functions. Measurement information such as meter reading data measured by these gas meters with wireless functions is transmitted to a monitoring device in a monitoring center directly or via a repeater.

[0003] Patent Document 1 describes a protection device for a USB communication line connecting a host device and a peripheral device. This protection device is provided with a charge discharge unit, such as a varistor, connected to the USB data line to discharge static electricity on the USB data line to the outside, and a selector switch for switching between connection and disconnection is provided between the charge discharge unit and the ground line. In this case, the selector switch is controlled by a USB controller based on whether the USB cable is connected or not, i.e., whether current is detected in the USB power line. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-116987 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, when assembling the above-mentioned gas meter with wireless functionality, it is expected that an operator will manually connect an external antenna by soldering or other means to an electronic circuit board on which a communication unit consisting of a wireless communication module is mounted. In this case, the operator connects the external antenna to the communication signal line from the communication unit, but there is a risk that electrostatic discharge (ESD) from the operator may damage the communication unit. Therefore, it is conceivable to connect an electrostatic discharge (ESD) protection component such as a TVS diode between the communication signal line and the ground, but this poses a problem in that the capacitance component of the electrostatic discharge protection component degrades the communication signal waveform when communication is performed after the gas meter with wireless functionality is installed.

[0006] Furthermore, the electronic circuit board is externally equipped with a gas flow rate measuring unit, a gas pressure measuring unit, etc. Measurement values ​​from these measuring units are transmitted to a control unit mounted on the electronic circuit board via a signal line connected to the control unit. While it is conceivable to connect electrostatic discharge protection components to these signal lines, there is the same problem as described above in that the capacitance component of the electrostatic discharge protection component degrades the signal waveform transmitted through the signal line.

[0007] The present invention has been made to solve the above-mentioned problems, and aims to provide a wireless device that can implement ESD countermeasures when attaching an external device and can prevent deterioration of the signal waveform transmitted through the signal line connected to the external device. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, a wireless device according to one embodiment of the present invention is a wireless device having an electronic circuit board having a communication unit and a control unit that wirelessly transmit measurement values ​​of fluid physical quantities to an external device, and an external device connected to a signal line from at least one of the communication unit and the control unit, and is equipped with a changeover switch connected between the signal line and a ground unit and switching between a conductive state and a non-conductive state, so that during the assembly work of the wireless device, when a worker connects the external device to the signal line, the changeover switch becomes conductive and the signal line and the ground unit are electrically connected, and when the worker performs a predetermined action after connecting the external device to the signal line, the changeover switch becomes non-conductive and the signal line and the ground unit are electrically disconnected.

[0009] According to this configuration, when a worker connects an external device to a signal line during assembly of a wireless device, the selector switch enters a conductive state, electrically connecting the signal line to the ground. As a result, when the worker installs the external device, static electricity stored on the worker is released from the signal line to the ground, preventing damage to the communication or control unit connected to the signal line and providing ESD protection. Furthermore, when the worker performs a predetermined action after connecting the external device to the signal line, the selector switch enters a non-conductive state, electrically disconnecting the signal line from the ground. This prevents degradation of the signal waveform transmitted through the signal line due to the capacitance of the ESD protection component, which would occur if the ESD protection component were directly connected between the signal line and the ground when the wireless device is assembled and installed. [Effects of the Invention]

[0010] The present invention has the configuration described above, and has the effect of providing a wireless device that can implement ESD countermeasures when attaching an external device more simply and reliably than the means of Patent Document 1, and can prevent deterioration of the signal waveform transmitted through a signal line connected to the external device. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram of an example of a wireless device according to this embodiment. [Figure 2] FIG. 2 is a schematic diagram showing an ESD protection circuit section of the first configuration example. [Figure 3] FIG. 3 is a schematic diagram showing an ESD protection circuit section of the second configuration example. [Figure 4] FIG. 4 is a schematic diagram showing an ESD protection circuit section of the third configuration example. [Figure 5] FIG. 5 is a schematic diagram showing an ESD protection circuit section of the fourth configuration example. [Figure 6] FIG. 6 is a schematic diagram showing a modified ESD protection circuit section. DETAILED DESCRIPTION OF THE INVENTION

[0012] Preferred embodiments of the present invention will be described below with reference to the drawings. In the following, identical or corresponding elements will be designated by the same reference numerals throughout the drawings, and redundant explanations may be omitted. Furthermore, the drawings are schematic illustrations of the respective components for ease of understanding, and the shapes, dimensional ratios, etc. may not be accurately depicted.

[0013] (Embodiment) FIG. 1 is a schematic diagram of an example wireless device in this embodiment. The wireless device GM shown in FIG. 1 is a gas meter with wireless communication capabilities. The wireless device GM has a case 1. A gas pipe P1 is inserted into the case 1. The gas pipe P1 inside the case 1 is provided with a shutoff valve 11, a flow rate measuring unit 12, a pressure measuring unit 13, and a temperature measuring unit 14. The case 1 includes a main body 1b and an openable and closable lid 1a, as shown in FIGS. 2 and 3, for example.

[0014] The flow rate measuring unit 12 is configured, for example, by a known ultrasonic flow meter, and measures the gas flow rate at regular intervals and transmits the measured value to the control unit 10. The pressure measuring unit 13 has a known pressure sensor, measures the gas pressure at regular intervals and transmits the measured value to the control unit 10. The temperature measuring unit 14 has a known temperature sensor, measures the gas temperature at regular intervals and transmits the measured value to the control unit 10. The shutoff valve 11 is controlled by the control unit 10 to be in a normally open state, and is closed when the control unit 10 detects any abnormality.

[0015] Also housed within the case 1 are an electronic circuit board 20 made of a printed circuit board, a display unit 15, an external antenna 17 which is an example of an external device, and a power supply unit 18. The electronic circuit board 20 is equipped with a control unit 10, a communication unit 16, an ESD protection circuit unit 2, etc. The ESD protection circuit unit 2 includes an electrostatic discharge protection component 22 and a changeover switch 23.

[0016] The display unit 15 has, for example, a display device such as a liquid crystal display or an LED lamp, and can display various information.

[0017] The communication unit 16 is made up of a wireless communication circuit and is configured to be able to communicate wirelessly with a predetermined external device via an external antenna 17. The external antenna 17 is connected to a signal line 21 which is connected to the communication unit 16. When transmitting information from the communication unit 16 to an external device, a communication signal is transmitted to the signal line 21. A connection portion 25 between the external antenna 17 and the signal line 21 may be formed by soldering or may be formed by a connector.

[0018] The control unit 10 is configured with a microcomputer or microcontroller, etc., and includes a CPU and memory (ROM and RAM), etc. The CPU executes a control program stored in the memory to control the display unit 15, communication unit 16, shutoff valve 11, etc. The memory can store various information in addition to the control program.

[0019] In addition, the control unit 10, for example, calculates the gas usage amount from the gas flow rate measured by the flow rate measuring unit 12 at predetermined time intervals, stores the calculated amount in memory, and transmits information on the integrated value of the gas usage amount (measured value of the fluid physical quantity) from the communication unit 16 to an external device at a predetermined timing.

[0020] The power supply unit 18 is configured by loading a battery into a battery loading section. The battery serves as a power source that supplies a power supply voltage to the electronic circuit board 20 via a power line 30 or the like.

[0021] The electrostatic discharge protection component 22 of the ESD protection circuit section 2 is formed, for example, by a unidirectional or bidirectional TVS (Transient Voltage Suppressor) diode, and is mounted on the electronic circuit board 20. One end of the electrostatic discharge protection component 22 is connected to the signal line 21, and the other end is connected to the ground section 24 via the changeover switch 23. The changeover switch 23 can be switched between a conductive state and a non-conductive state.

[0022] When an operator assembles this wireless device GM, for example, lid 1a of case 1 is opened, and shutoff valve 11, flow rate measurement unit 12, pressure measurement unit 13, temperature measurement unit 14, and gas pipe P1 are stored in main body 1b (see FIGS. 2 and 3), and then electronic circuit board 20 is connected to shutoff valve 11, flow rate measurement unit 12, pressure measurement unit 13, and temperature measurement unit 14, and electronic circuit board 20 is attached in a predetermined position. After this, the operator connects external antenna 17 to signal line 21 of electronic circuit board 20, loads a battery into the battery loading portion of power supply unit 18, and closes lid 1a of case 1.

[0023] In this embodiment, an ESD protector 22 is connected to the signal line 21, and a changeover switch 23 is connected between the ESD protector 22 and the grounding part 24. When an operator connects the external antenna 17 to the signal line 21 during the assembly work of the wireless device GM as described above, the changeover switch 23 is brought into a conductive state, electrically connecting the ESD protector 22 and the grounding part 24. As a result, when the operator attaches the external antenna 17, static electricity charged to the operator is discharged from the signal line 21 through the ESD protector 22 to the grounding part 24, thereby preventing damage to the communication part 16 and achieving ESD protection.

[0024] Furthermore, after the worker connects external antenna 17 to signal line 21, if the worker performs a predetermined action (hereinafter referred to as "predetermined action A"), changeover switch 23 becomes non-conductive, electrically disconnecting ESD protection component 22 from grounding part 24. As a result, when wireless device GM is installed and measurement information consisting of an integrated value of gas usage is transmitted from communication unit 16 to an external device, the measurement information can be transmitted accurately without degradation of the communication signal waveform due to the capacitance component of ESD protection component 22. A specific example of the configuration of such an ESD protection circuit unit 2 is described below.

[0025] [First configuration example] Fig. 2 is a schematic diagram showing an ESD protection circuit section of a first configuration example. The ESD protection circuit section 2A shown in Fig. 2 uses a push switch 23a as the selector switch 23, which is arranged so as to switch between a conductive state and a non-conductive state depending on whether the lid 1a of the case 1 is open or closed. The push switch 23a is in a conductive state when the lid 1a is open, and in a non-conductive state when the lid 1a is closed.

[0026] In this case, when assembling the wireless device GM, the worker connects the external antenna 17 to the signal line 21 with the lid 1a of the case 1 open. At this time, the push switch 23a is in a conductive state, so the electrostatic discharge protection component 22 is electrically connected to the grounding part 24 and is in a state where it functions effectively, thereby achieving ESD protection. Here, for example, a unidirectional TVS diode 22a is used as the electrostatic discharge protection component 22.

[0027] On the other hand, when the assembly work of wireless device GM is completed, lid 1a is closed, so push switch 23a is in a non-conductive state and electrostatic discharge protection component 22 is electrically disconnected from grounding part 24. In other words, when wireless device GM is assembled, installed, and used, measurement information can be transmitted accurately without deterioration of the communication signal waveform of signal line 21. In this case, predetermined action A by the worker is the action of the worker closing lid 1a.

[0028] [Second configuration example] Fig. 3 is a schematic diagram showing an ESD protection circuit section of a second configuration example. Similar to the ESD protection circuit section 2A shown in Fig. 2, the ESD protection circuit section 2B shown in Fig. 3 includes an electrostatic discharge protection component 22 and a push switch 23a.

[0029] The ESD protection circuit 2B shown in FIG. 3 uses a bidirectional TVS diode 22b as the ESD protection component 22. Here, a predetermined circuit 26 is connected to the wiring W1 between the ESD protection component 22 and the push switch 23a. The predetermined circuit 26 includes, for example, a pull-up resistor R1 connected between the power supply line 30 and the wiring W1 and a cover open / closed state detector 27 connected to the wiring W1. The cover open / closed state detector 27 detects the open / closed state of the cover 1a by detecting the potential level of the wiring W1. For example, when the cover 1a is open, the push switch 23a is in a conductive state, the wiring W1 is electrically connected to the ground 24, and the potential of the wiring W1 is low. On the other hand, when the cover 1a is closed, the push switch 23a is in a non-conductive state, the wiring W1 is electrically disconnected from the ground 24, and the potential of the wiring W1 is high due to the potential of the power supply line 30.

[0030] If such a predetermined circuit 26 is connected to the wiring W1, it is undesirable to use a unidirectional TVS diode 22a (FIG. 2) as the ESD protection component 22, because noise from the predetermined circuit 26 may be transmitted to the signal line 21 during normal operation when the cover 1a is closed and the push switch 23a is non-conductive. Therefore, by using a bidirectional TVS diode 22b, it is possible to prevent noise from the predetermined circuit 26 from being transmitted to the signal line 21. Note that the predetermined circuit 26 is not limited to the above example, and may be a circuit other than the circuit shown in FIG. 3.

[0031] 2, a bidirectional TVS diode 22b may also be used as the electrostatic discharge protection component 22. Alternatively, a Zener diode, a varistor, or the like may also be used.

[0032] [Third configuration example] Fig. 4 is a schematic diagram showing an ESD protection circuit section of a third configuration example. In the ESD protection circuit section 2C shown in Fig. 4, a semiconductor switch 23b is used as the changeover switch 23. This semiconductor switch 23b is a switching element formed of, for example, an n-channel MOSFET. An output terminal of a logical negation circuit (NOT circuit) 28 is connected to a control terminal (gate) of the semiconductor switch 23b, and a power supply line 30 is connected to an input terminal of the logical negation circuit 28. Furthermore, a unidirectional TVS diode, a bidirectional TVS diode, or the like can be used as the electrostatic discharge protection component 22.

[0033] In the first example of this third configuration example (when there is no power switch 31), when battery 18D is not loaded in battery loading section 18C of power supply section 18, semiconductor switch 23b is in a conductive state, and electrostatic discharge protection component 22 is electrically connected to ground section 24 and functions effectively. In this state, an operator can connect external antenna 17 to signal line 21 to achieve ESD protection.

[0034] On the other hand, when the worker loads battery 18D into battery loading section 18C after connecting external antenna 17 to signal line 21, semiconductor switch 23b becomes non-conductive and ESD protection component 22 becomes electrically disconnected from grounding section 24. In other words, when wireless device GM is assembled, installed, and used, measurement information can be transmitted accurately without degradation of the communication signal waveform of signal line 21. In this case, predetermined action A by the worker is the worker loading battery 18D into battery loading section 18C.

[0035] Next, in a second example of the third configuration example, in Fig. 4, a power switch 31 is inserted in the power line 30. The power switch 31 can be manually switched between a conductive state and a non-conductive state.

[0036] In the second example of this third configuration example, regardless of whether battery 18D is loaded in battery loading section 18C of power supply section 18, when power switch 31 is in the non-conductive state, semiconductor switch 23b is in the conductive state and electrostatic discharge protection component 22 is electrically connected to ground section 24 and functions effectively. In this state, an operator can connect external antenna 17 to signal line 21 to achieve ESD protection.

[0037] On the other hand, if the worker switches the power switch 31 from the non-conductive state to the conductive state with the battery 18D loaded in the battery loading section 18C after connecting the external antenna 17 to the signal line 21, the semiconductor switch 23b becomes non-conductive and the ESD protection component 22 becomes electrically disconnected from the grounding section 24. In other words, when the wireless device GM is assembled, installed, and used, the measurement information can be transmitted accurately without degradation of the communication signal waveform of the signal line 21. In this case, the predetermined action A by the worker is the worker switching the power switch 31 from the non-conductive state to the conductive state.

[0038] [Fourth configuration example] FIG. 5 is a schematic diagram showing an ESD protection circuit section of a fourth configuration example. In the ESD protection circuit section 2D shown in FIG. 5, a conductive / non-conductive state switching section 23c formed of, for example, a toggle switch is used as the changeover switch 23. Furthermore, a unidirectional TVS diode or a bidirectional TVS diode can be used as the electrostatic discharge protection component 22. Note that, although FIG. 5 shows a toggle switch as an example of the conductive / non-conductive state switching section 23c, the conductive / non-conductive state switching section 23c may be formed of a jumper switch formed of a jumper pin and a jumper plug, or may be formed using a solder jumper.

[0039] In this fourth configuration example, when an operator connects the external antenna 17 to the signal line 21, the conductive / non-conductive state switching unit 23c is in the conductive state, and the electrostatic discharge protection component 22 is in an electrically connected and functional state with the grounding part 24. In this state, the operator can connect the external antenna 17 to the signal line 21, thereby achieving ESD protection.

[0040] On the other hand, if the worker switches the conductive / non-conductive state switching unit 23c from the conductive state to the non-conductive state after connecting the external antenna 17 to the signal line 21, the ESD protection component 22 will be electrically disconnected from the grounding part 24. In other words, when the wireless device GM is assembled, installed, and used, the measurement information can be transmitted accurately without degradation of the communication signal waveform of the signal line 21. In this case, the predetermined action A by the worker is the action of the worker switching the conductive / non-conductive state switching unit 23c from the conductive state to the non-conductive state.

[0041] [Modification] FIG. 6 is a schematic diagram showing a modified ESD protection circuit. In the ESD protection circuit 2E shown in FIG. 6, a semiconductor switch 23b made of an n-channel MOSFET similar to that shown in FIG. 4 is used as the selector switch 23. The control terminal (gate) of the semiconductor switch 23b is connected to the output terminal of a logical negation circuit 29, and the input terminal of the logical negation circuit 29 is connected to the control unit 10. For example, the control unit 10 controls the semiconductor switch 23b to be in a conductive state by outputting a low-level signal to the logical negation circuit 29, and to be in a non-conductive state by outputting a high-level signal to the logical negation circuit 29. In other words, the control unit 10 controls the switching of the semiconductor switch 23b between a conductive state and a non-conductive state. Furthermore, the electrostatic discharge protection component 22 can be a unidirectional TVS diode, a bidirectional TVS diode, or the like.

[0042] In a first example of this modification, after wireless device GM is assembled and installed, control unit 10 sets semiconductor switch 23b to a non-conductive state immediately before causing communication unit 16 to perform the first wireless communication, and thereafter maintains this non-conductive state. As a result, after wireless device GM is assembled and installed, when communication is performed by communication unit 16, electrostatic discharge protection component 22 is electrically disconnected from grounding part 24, so that measurement information can be transmitted accurately without degradation of the communication signal waveform of signal line 21.

[0043] In this second example of the modification, after wireless device GM is assembled and installed, control unit 10 sets semiconductor switch 23b to a non-conductive state each time it causes communication unit 16 to perform wireless communication, immediately before the communication is performed, and sets semiconductor switch 23b to a conductive state immediately after the communication is completed by communication unit 16. As a result, after wireless device GM is assembled and installed, when communication is performed by communication unit 16, electrostatic discharge protection component 22 is electrically disconnected from grounding part 24, and measurement information can be transmitted accurately without degradation of the communication signal waveform of signal line 21.

[0044] Furthermore, in the first and second examples of the above-described modified examples, when an operator connects external antenna 17 to signal line 21 during assembly of wireless device GM, power supply unit 18 does not supply power to electronic circuit board 20, semiconductor switch 23b is in a conductive state, and electrostatic discharge protection component 22 is electrically connected to grounding portion 24 and is in a state in which it functions effectively. In this state, an operator can connect external antenna 17 to signal line 21 to achieve ESD protection. After power supply voltage is supplied to electronic circuit board 20 from power supply unit 18, control unit 10 keeps semiconductor switch 23b in a conductive state until immediately before causing communication unit 16 to perform at least the first wireless communication.

[0045] In the present embodiment described above, the external device that communicates wirelessly with the communication unit 16 of the wireless device GM may be a monitoring device installed in a monitoring center, or may be a repeater that relays communication between the wireless device GM and the monitoring device. Furthermore, a group may be formed of multiple wireless devices GM, and the repeater may be a repeater attached to one wireless device GM in the group. In this case, the repeater collects measurement information from the multiple wireless devices GM in the group and transmits it to the monitoring device.

[0046] In this embodiment, except for the second configuration example shown in FIG. 3, a configuration without the electrostatic discharge protection component 22 is also possible. That is, as the ESD protection circuit section 2, only the changeover switch 23 (23a, 23b, 23c) may be connected between the signal line 21 and the ground section 24. In this case, when a worker connects the external antenna 17 to the signal line 21 during the assembly work of the wireless device GM, the changeover switch 23 becomes conductive, electrically connecting the signal line 21 and the ground section 24. As a result, when the worker attaches the external antenna 17, static electricity charged to the worker is released from the signal line 21 to the ground section 24, thereby preventing damage to the communication section 16 connected to the signal line 21 and achieving ESD protection. Furthermore, in the first, third and fourth configuration examples, when the wireless device GM is assembled and installed, the changeover switch 23 is brought into a non-conductive state, and the signal line 21 and the grounding part 24 are electrically disconnected, thereby preventing the signal waveform transmitted through the signal line 21 from being deteriorated by the capacitance component of the electrostatic discharge protection component, as would occur, for example, if the electrostatic discharge protection component were directly connected between the signal line 21 and the grounding part 24.

[0047] In this embodiment, the ground portion 24 can be preferably connected to a frame ground, a signal ground, an earth ground, or the like.

[0048] In the present embodiment, the external antenna 17 is given as an example of an external device, and the ESD countermeasure circuit units 2A to 2E are applied to the signal line 21, but this is not limiting. For example, any one or more of the flow rate measurement unit 12, pressure measurement unit 13, and temperature measurement unit 14 configured as an ultrasonic flowmeter may be used as external devices, and the ESD countermeasure circuit units 2A to 2E may be applied to any one or more of the signal lines 32, 33, and 34 between the flow rate measurement unit 12, pressure measurement unit 13, and temperature measurement unit 14 and the control unit 10 within the electronic circuit board 20. The ESD countermeasure circuit units 2A to 2E may use TVS diodes, Zener diodes, varistors, etc.

[0049] In addition, in this embodiment, the wireless device GM has been described as a gas meter having a wireless communication function, but it may also be a water meter having a wireless communication function. That is, the communication unit 16 of the wireless device GM may be configured to wirelessly transmit measurement information consisting of measurement values ​​of fluid physical quantities, such as gas or water usage, to an external device.

[0050] Furthermore, the above-described ESD protection circuit sections 2A to 2E may also be applied to general electronic devices other than gas meters and water meters.

[0051] From the above description, many modifications and other embodiments of the present invention will be apparent to those skilled in the art. Therefore, the above description should be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode for carrying out the present invention. Details of the structure and / or function thereof may be substantially changed without departing from the spirit of the present invention.

[0052] (Addendum) The above description of the embodiments discloses the following techniques.

[0053] (Technology 1) A wireless device having an electronic circuit board with a communication unit and a control unit that wirelessly transmits measurement values ​​of fluid physical quantities to an external device, and an external device connected to a signal line from at least one of the communication unit and the control unit, the wireless device further comprising a changeover switch connected between the signal line and a grounding unit and switching between a conductive state and a non-conductive state, wherein, during assembly of the wireless device, when a worker connects the external device to the signal line, the changeover switch is turned on and the signal line and the grounding unit are electrically connected, and when the worker performs a predetermined action after connecting the external device to the signal line, the changeover switch is turned off and the signal line and the grounding unit are electrically disconnected.

[0054] According to this configuration, when a worker connects an external device to a signal line during assembly of a wireless device, the selector switch enters a conductive state, electrically connecting the signal line to the ground. As a result, when the worker installs the external device, static electricity stored on the worker is released from the signal line to the ground, preventing damage to the communication or control unit connected to the signal line and providing ESD protection. Furthermore, when the worker performs a predetermined action after connecting the external device to the signal line, the selector switch enters a non-conductive state, electrically disconnecting the signal line from the ground. This prevents degradation of the signal waveform transmitted through the signal line due to the capacitance of the ESD protection component, which may occur when, for example, an ESD protection component is directly connected between the signal line and the ground when the wireless device is assembled and installed.

[0055] (Technology 2) The wireless device according to Technology 1, further comprising an electrostatic discharge protection component mounted on the electronic circuit board and inserted and connected between the signal line and the changeover switch.

[0056] According to this configuration, when a worker connects an external device to a signal line during assembly of a wireless device, the selector switch enters a conductive state, electrically connecting the ESD countermeasure component to the ground. As a result, when the worker installs the external device, static electricity charged on the worker is discharged from the signal line through the ESD countermeasure component to the ground, thereby preventing damage to the communication unit or control unit connected to the signal line and achieving ESD protection. Furthermore, when the worker performs a predetermined action after connecting the external device to the signal line, the selector switch enters a non-conductive state, electrically disconnecting the ESD countermeasure component from the ground. This prevents degradation of the signal waveform transmitted through the signal line due to the capacitive component of the ESD countermeasure component when the wireless device is assembled and installed. For example, if the ESD countermeasure component is connected to the signal line from the communication unit, when the communication unit transmits a measurement value of a fluid physical quantity to an external device, the communication signal waveform is not degraded by the capacitive component of the ESD countermeasure component, and information (measurement information) of the fluid physical quantity, such as gas or water usage, can be accurately transmitted.

[0057] (Technology 3) The wireless device according to Technology 1 or 2, wherein the electronic circuit board and the external device are housed in a case having an openable lid, the changeover switch is configured to be in a conductive state when the lid is open and to be in a non-conductive state when the lid is closed, and the predetermined action is the action of closing the lid.

[0058] With this configuration, when assembling a wireless device, the worker connects an external device to the signal line with the case lid open, which puts the selector switch into a conductive state, electrically connecting the signal line and the ground, thereby achieving ESD protection. Also, when the wireless device is assembled and installed, the case lid is closed, which puts the selector switch into a non-conductive state, electrically disconnecting the signal line and the ground, thereby preventing degradation of the signal waveform transmitted through the signal line.

[0059] (Technology 4) A wireless device according to Technology 2, wherein a predetermined circuit is connected to wiring connecting the electrostatic discharge protection component and the changeover switch, the electrostatic discharge protection component is a bidirectional TVS diode, the electronic circuit board and the external device are housed in a case having an openable / closable lid, the changeover switch is configured to be in a conductive state when the lid is open and to be in a non-conductive state when the lid is closed, and the predetermined action is an action of closing the lid.

[0060] With this configuration, when a predetermined circuit is connected to the wiring, it is possible to prevent noise from the predetermined circuit from being transmitted to the signal line during normal operating conditions with the lid closed.

[0061] (Technology 5) A wireless device according to Technology 1 or 2, which includes a battery loading section for loading a battery that serves as a power source for the electronic circuit board, and is configured so that the changeover switch is in a conductive state when the battery is not loaded in the battery loading section and is in a non-conductive state when the battery is loaded in the battery loading section, and the predetermined action is the action of loading the battery into the battery loading section.

[0062] With this configuration, when assembling a wireless device, an operator connects an external device to a signal line by ensuring that a battery is not loaded in the battery loading section, which causes the selector switch to be in a conductive state and electrically connects the signal line to the ground, thereby achieving ESD protection. Also, when the wireless device is assembled and installed, a battery is loaded in the battery loading section, which causes the selector switch to be in a non-conductive state and electrically disconnects the signal line from the ground, preventing degradation of the signal waveform transmitted through the signal line.

[0063] (Technology 6) A wireless device according to Technology 1 or 2, comprising: a power supply that supplies a power supply voltage to the electronic circuit board through a power line; and a power switch that is inserted in the power line and that can be manually switched between a conductive state and a non-conductive state, wherein the changeover switch is configured to be in a conductive state when the power switch is in a non-conductive state, and to be in a non-conductive state when the power switch is in a conductive state, and wherein the predetermined action is an action of switching the power switch from a non-conductive state to a conductive state.

[0064] With this configuration, when assembling a wireless device, an operator connects an external device to a signal line by keeping the power switch in a non-conductive state, which electrically connects the signal line to the ground, thereby achieving ESD protection. Also, when the wireless device is assembled and installed, the power switch is in a conductive state, which electrically disconnects the signal line from the ground, thereby preventing degradation of the signal waveform transmitted through the signal line.

[0065] (Technology 7) The wireless device according to Technology 1 or 2, wherein the changeover switch is a conductive / non-conductive state switching unit that can switch between a conductive state and a non-conductive state, and the predetermined action is an action of switching the conductive / non-conductive state switching unit from a conductive state to a non-conductive state.

[0066] According to this configuration, when an operator connects an external device to a signal line during assembly of a wireless device, the conductive / non-conductive state switching unit is set to the conductive state, thereby electrically connecting the signal line and the ground, and thus providing ESD protection. Also, when the wireless device is assembled and installed, the conductive / non-conductive state switching unit is set to the non-conductive state, thereby electrically disconnecting the signal line and the ground, thereby preventing degradation of the signal waveform transmitted through the signal line. [Industrial Applicability]

[0067] The present invention is useful as a wireless device or the like that can implement ESD countermeasures when an external device is attached and can prevent degradation of the signal waveform transmitted through a signal line connected to the external device. [Explanation of symbols]

[0068] GM radio equipment 1 case 1a Case lid 1b Case body 11 Shut-off valve 12 Flow measurement section 13 Pressure measurement section 14 Thermometer side 16 Communications Department 17 External Antenna 18C battery loading section 18D battery 20. Electronic circuit board 21, 32, 33, 34 signal lines 22 Electrostatic discharge protection parts 22a Unidirectional TVS Diode 22b Bidirectional TVS Diode 23 Selector switch 23a Push switch 23b Semiconductor switch 23c Conduction / non-conduction state switching section 24 Grounding part 26 Predetermined circuit 30 Power line 31 Power switch

Claims

1. A wireless device comprising: an electronic circuit board having a communication unit and a control unit that wirelessly transmit a measurement value of a fluid physical quantity to an external device; and an external device connected to a signal line from at least one of the communication unit and the control unit, a changeover switch connected between the signal line and a ground portion, the changeover switch switching between a conductive state and a non-conductive state; In the assembly work of the wireless device, when a worker connects the external device to the signal line, the changeover switch is in a conductive state, and the signal line and the grounding part are electrically connected, and when the worker performs a predetermined action after connecting the external device to the signal line, the changeover switch is in a non-conductive state, and the signal line and the grounding part are electrically disconnected. Radio equipment.

2. an electrostatic discharge protection component mounted on the electronic circuit board and inserted and connected between the signal line and the changeover switch; 10. The wireless device of claim 1.

3. the electronic circuit board and the external device are housed in a case having an openable / closable lid; The changeover switch is configured to be in a conductive state when the lid is open, and to be in a non-conductive state when the lid is closed, The predetermined action is an action of closing the lid.

3. The wireless device according to claim 1 or 2.

4. a predetermined circuit is connected to a wiring that connects the electrostatic discharge protection component and the selector switch, the electrostatic discharge protection component is a bidirectional TVS diode, the electronic circuit board and the external device are housed in a case having an openable / closable lid; The changeover switch is configured to be in a conductive state when the lid is open, and to be in a non-conductive state when the lid is closed, The predetermined action is an action of closing the lid.

3. The wireless device of claim 2.

5. a battery loading section for loading a battery that serves as a power source for the electronic circuit board; The changeover switch is configured to be in a conductive state when the battery is not loaded in the battery loading section, and to be in a non-conductive state when the battery is loaded in the battery loading section, the predetermined action is an action of loading the battery into the battery loading section; 3. The wireless device according to claim 1 or 2.

6. a power supply that supplies a power supply voltage to the electronic circuit board through a power supply line; a power switch inserted in the power line and manually switching between a conductive state and a non-conductive state; The changeover switch is configured to be in a conductive state when the power switch is in a non-conductive state, and to be in a non-conductive state when the power switch is in a conductive state, the predetermined action is an action of switching the power switch from a non-conductive state to a conductive state; 3. The wireless device according to claim 1 or 2.

7. the changeover switch is a conductive / non-conductive state switching unit that can switch between a conductive state and a non-conductive state, the predetermined action is an action of switching the conductive / non-conductive state switching unit from a conductive state to a non-conductive state; 3. The wireless device according to claim 1 or 2.

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