Wireless communication systems, wireless communication equipment

Abstract

To provide a radio communication system and a radio communication device capable of suppressing increase of power consumption while restricting complication of communication configuration.SOLUTION: A TPMS includes a tire sensor 2 having a first control part 23 capable of switching communication mode between standby state and wakeup state and operating on a battery 25 as its power supply. The TPMS is configured to be capable of performing BLE communication with the tire sensor 2, and includes an on-vehicle unit 3 capable of establishing connection with the tire sensor 2 by requesting connection to the tire sensor 2 if it receives an advertising signal from the tire sensor 2. The tire sensor 2 verifies a radio signal with a verification pattern corresponding to a wakeup signal if a radio signal on a frequency band based on a BLE communication standard transmitted by the on-vehicle unit 3 is received during the standby state of the first control part 23. Then, the tire sensor 2 switches the first control part 23 to the wakeup state according to the verification result.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present disclosure relates to a wireless communication system and a wireless communication device.

Background Art

[0002] Conventionally, a system that performs wireless communication (hereinafter also referred to as BLE communication) conforming to the BLE communication standard between a battery-powered portable communication device such as a smart key and an in-vehicle communication device is known (see, for example, Patent Document 1). In this BLE communication, it is common to establish a communication connection between each communication device by intermittently activating the control unit of one communication device to broadcast an advertisement signal and having the other communication device that has scanned this signal make a connection request.

[0003] On the other hand, Patent Document 1 discloses a technique for switching a standby communication device to a wake-up state by combining wireless communication conforming to the BLE communication standard and wireless communication using an LF signal or the like in order to suppress power consumption of wireless communication. Specifically, the system described in Patent Document 1 is configured to switch the communication device to the wake-up state by wireless communication using an LF signal or the like, rather than intermittently switching the control unit of the communication device to the wake-up state to broadcast an advertisement signal. Note that “BLE” is an abbreviation for Bluetooth (registered trademark) Low Energy. Also, “LF” is an abbreviation for Low Frequency.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the technology disclosed in Patent Document 1 requires separate equipment for wireless communication using LF signals, etc., in addition to the equipment for BLE communication, which significantly complicates the communication configuration.

[0006] This disclosure aims to provide wireless communication systems and wireless communication equipment that can suppress increased power consumption while keeping the complexity of the communication configuration under control. [Means for solving the problem]

[0007] The invention described in claim 1 is, A wireless communication system, A first device (2) that operates using a battery (25) as a power source and has a control unit (23) that can switch the communication mode between a standby state and a wake-up state, The system includes a second device (3, 5) which is configured to perform wireless communication in accordance with the BLE communication standard with the first device, and which, upon receiving an advertisement signal from the first device, can request a connection from the first device and establish a connection with the first device. The first device includes a startup unit (27, 27A) that, when the control unit is in standby mode, receives a wireless signal in a frequency band compliant with the BLE communication standard emitted by the second device, compares the wireless signal with a matching pattern corresponding to the wake-up signal, and switches the control unit to the wake-up state according to the matching result. Occasionally, The second device transmits an advertisement signal as a wake-up signal to the first device. The startup unit (27) includes a matching unit (271) that matches at least a portion of the advertised signal emitted by the second device with a matching pattern, and a switching unit (272) that switches the control unit to a wake-up state according to the matching result in the matching unit.

[0008] Thus, if the control unit of the first device switches from standby to wake-up state upon receiving a wake-up signal from the second device, there is no need to intermittently activate the control unit of the first device, thus reducing the power consumption of the first device. Furthermore, since the wake-up signal emitted by the second device is a signal in the frequency band compliant with the BLE communication standard, there is no need to add a dedicated antenna to the first device to receive the wake-up signal.

[0009] Therefore, the wireless communication system of this disclosure can suppress power consumption while keeping the complexity of the communication configuration under control.

[0010] Claim 5 The invention described is A wireless communication device that operates using a battery (25) as a power source, A control unit (23) that can switch the communication mode between standby and wake-up states, This system performs wireless communication with external devices (3, 5) in accordance with the BLE communication standard, and includes a communication circuit (24) that establishes a connection with the external device upon a connection request from the external device, The control unit, when in standby mode, receives a wireless signal in a frequency band compliant with the BLE communication standard, compares the wireless signal with a matching pattern corresponding to the wake-up signal, and switches the control unit to the wake-up state according to the matching result. (27) picture, The external device is configured to emit an advertised signal as a wake-up signal. The startup unit (27) includes a matching unit (271) that matches at least a portion of the advertised signal emitted by an external device with a matching pattern, and a switching unit (272) that switches the control unit to a wake-up state according to the matching result in the matching unit.

[0011] Thus, if the control unit of the wireless communication device switches from standby to wake-up state upon receiving a wake-up signal from the second device, there is no need to intermittently activate the control unit of the wireless communication device. In addition, since the wake-up signal emitted by the external device is a signal in the frequency band compliant with the BLE communication standard, there is no need to add a dedicated antenna to the wireless communication device to receive the wake-up signal.

[0012] Therefore, the wireless communication system of this disclosure can reduce power consumption while keeping the complexity of the communication configuration low compared to conventional systems.

[0013] The reference numerals in parentheses attached to each component indicate an example of the correspondence between that component and the specific components described in the embodiments described later. [Brief explanation of the drawing]

[0014] [Figure 1] It is a schematic configuration diagram of a tire pressure monitoring system that constitutes a wireless communication system according to the first embodiment. [Figure 2] It is a block diagram showing a schematic configuration of a tire sensor. [Figure 3] It is a block diagram showing a schematic configuration of a first communication circuit included in the tire sensor of the first embodiment. [Figure 4] It is an explanatory diagram for explaining a collation unit. [Figure 5] It is a block diagram showing a schematic configuration of an in-vehicle unit. [Figure 6] It is a flowchart showing the flow of communication processing executed by an in-vehicle unit or the like. [Figure 7] It is an explanatory diagram for explaining wireless communication between the tire sensor and the in-vehicle unit in the first embodiment. [Figure 8] It is an explanatory diagram for explaining a wake-up signal emitted by the in-vehicle unit of the first embodiment. [Figure 9] It is an explanatory diagram for explaining wireless communication between the tire sensor and the in-vehicle unit in the second embodiment. [Figure 10] It is an explanatory diagram for explaining a wake-up signal emitted by the in-vehicle unit of the second embodiment. [Figure 11] It is a block diagram showing a schematic configuration of a first communication circuit included in the tire sensor of the second embodiment.

Embodiments for Carrying Out the Invention

[0015] Embodiments of this disclosure will be described below with reference to the drawings. In the following embodiments, parts that are the same as or equivalent to those described in the prior embodiments will be denoted by the same reference numerals, and their descriptions may be omitted. Also, if only a part of a component is described in an embodiment, the components described in the prior embodiments can be applied to the other parts of that component. The following embodiments can be partially combined with each other, even if not explicitly stated, as long as it does not impede the combination.

[0016] (First Embodiment) This embodiment will be described with reference to Figures 1 to 8. This disclosure describes an example in which a wireless communication system is applied to a tire pressure monitoring system (hereinafter referred to as TPMS). The TPMS is a system that monitors the tire pressure of wheels 6a to 6d of a vehicle 1. The TPMS includes a tire sensor 2, an on-board unit 3, a display device 4, and a maintenance tool 5. In this embodiment, the tire sensor 2 corresponds to the “first device”, and the on-board unit 3 and maintenance tool 5 correspond to the “second device”. Also in this embodiment, the tire sensor 2 corresponds to the “wireless communication device”, and the on-board unit 3 and maintenance tool 5 correspond to the “external device”.

[0017] The tire sensor 2 is installed on each of the multiple wheels 6a to 6d, including the tires, and detects the tire pressure, etc., and stores the tire pressure information indicating the detection result within the frame and transmits it.

[0018] The on-board unit 3 is installed on the vehicle body 7 side of the vehicle 1. It receives frames transmitted from the tire sensor 2 and performs various processing and calculations based on the information stored therein to detect tire pressure.

[0019] The in-vehicle unit 3 is configured to enable BLE communication with the tire sensor 2. When the in-vehicle unit 3 receives an advertisement signal from the tire sensor 2, it requests a connection from the tire sensor 2 and establishes a connection with the tire sensor 2.

[0020] Display device 4 is a device that displays information to be conveyed to the occupants. Display device 4 is installed in a location within the vehicle interior that is visible to the driver. Specifically, display device 4 consists of warning lamps and a display installed on the instrument panel. When display device 4 receives a signal from the in-vehicle unit 3 indicating that the tire pressure has dropped, it displays a message to that effect to inform the driver of the drop in tire pressure.

[0021] Maintenance tool 5 is used to diagnose abnormalities in various components of vehicle 1, and is primarily used by vehicle 1 mechanics. Maintenance tool 5 is configured to enable BLE communication with tire sensor 2 and on-board unit 3. Alternatively, maintenance tool 5 may be configured to connect to on-board unit 3 via wired communication.

[0022] The general configuration of the tire sensor 2 will be described below with reference to Figures 2 to 4. As shown in Figure 2, the tire sensor 2 includes a sensing unit 21, an acceleration sensor 22, a first control unit 23, a first communication circuit 24, a first communication antenna 26, and a battery 25.

[0023] The sensing unit 21 detects tire pressure and tire internal temperature. Specifically, the sensing unit 21 is configured to include a pressure sensor and a temperature sensor, and outputs detection signals corresponding to tire pressure and detection signals corresponding to tire internal temperature.

[0024] The acceleration sensor 22 detects the acceleration due to gravity and the acceleration generated by the rotation of each wheel 6a to 6d. In this embodiment, the acceleration sensor 22 outputs a detection signal corresponding to the sum of the centrifugal acceleration acting radially on each wheel 6a to 6d and the acceleration due to gravity, which are the accelerations acting on the wheels 6a to 6d when they rotate.

[0025] The first control unit 23 is composed of a microcomputer equipped with a CPU, memory such as ROM or RAM, I / O, etc. The first control unit 23 executes predetermined processing according to a program stored in the built-in memory. The memory stores individual ID information, which includes unique identification information for identifying each tire sensor 2 and vehicle-specific identification information for identifying the vehicle itself.

[0026] The first control unit 23 receives the detection signal output from the sensing unit 21, processes it, and modifies it as necessary, storing it in a frame along with the ID information of each tire sensor 2 as data indicating the detection result of the sensing unit 21. In other words, the first control unit 23 creates a frame containing data indicating the detection result of the sensing unit 21. The first control unit 23 sends the created frame to the first communication circuit 24. In the following description, the data indicating the detection result of the sensing unit 21 will be referred to as tire pressure data, or simply tire information. Note that the tire pressure data does not necessarily have to include all of this data; it may only contain data indicating the detection result of the tire pressure.

[0027] The first control unit 23 detects, based on the detection signal from the acceleration sensor 22, whether the acceleration is above a certain value, that is, whether the vehicle 1 is traveling at a predetermined speed or above, or whether the vehicle 1 is moving slowly or parked. The first control unit 23 also detects changes in tire pressure due to tire pressure adjustment, based on the detection signal from the sensing unit 21.

[0028] The first control unit 23 switches to a power-saving communication mode, standby, when communication with other devices is not required, in order to reduce power consumption. The first control unit 23 is a "control unit" that can switch the communication mode between standby and wake-up states.

[0029] Here, the standby state is a state in which the device is waiting for a signal and operates with less power consumption compared to the wake-up state. Specifically, the standby state is a state in which the device can receive wireless signals in the frequency band compliant with the BLE communication standard (i.e., the 2.4GHz band), but cannot transmit those wireless signals. In the standby state, the device is not always able to receive wireless signals; it periodically transitions to a state in which it can receive wireless signals. This suppresses power consumption.

[0030] The wake-up state is when the first control unit 23 is activated and capable of sending and receiving wireless signals conforming to the BLE communication standard. The wake-up state consumes more power than the standby state.

[0031] The first control unit 23, for example, when in the wake-up state, causes the first communication circuit 24 to transmit tire information via unidirectional communication at a predetermined timing. The transmission of tire information means transmitting a frame containing the tire information.

[0032] The first communication circuit 24 is a communication circuit that performs BLE communication between the in-vehicle unit 3 and the maintenance tool 5, etc. The first communication antenna 26 is an antenna for performing BLE communication with the in-vehicle unit 3 and the maintenance tool 5, etc.

[0033] The first communication circuit 24 transmits and receives wireless signals conforming to the BLE communication standard via the first communication antenna 26. BLE communication enables both unidirectional communication from the tire sensor 2 to the vehicle unit 3 and bidirectional communication between the tire sensor 2 and the vehicle unit 3.

[0034] The first communication circuit 24 includes a startup unit 27 that switches the first control unit 23 to a wake-up state when it receives a wake-up signal in a frequency band conforming to the BLE communication standard emitted by the in-vehicle unit 3 while the first control unit 23 is in a standby state. Specifically, when the first communication circuit 24 receives a wireless signal in a frequency band conforming to the BLE communication standard, it compares the wireless signal with a predetermined matching pattern corresponding to the wake-up signal and switches the first control unit 23 to a wake-up state according to the matching result.

[0035] BLE communication uses the 2.4GHz frequency band and employs the GFSK (GaussianFSK) modulation scheme. The first communication circuit 24 has a circuit configuration that corresponds to the communication method used in the aforementioned BLE communication.

[0036] Specifically, as shown in Figure 3, the first communication circuit 24 includes a low-noise amplifier (LNA) 241, a phase-locked loop (PLL) 242, a digital converter (ADC) 243, a demodulator 244, a data buffer 245, and a startup unit 27.

[0037] The first communication circuit 24 amplifies the received signal received by the first communication antenna 26 with a low-noise amplifier 241, synchronizes it with a lock signal emitted by the phase-lock circuit 242, and then converts it into a digital signal with a digital converter 243. The first communication circuit 24 then demodulates the digital signal converted by the digital converter 243 with a demodulator 244 and temporarily stores the demodulated signal data in a data buffer 245. The signal data demodulated by the demodulator 244 and the signal data stored in the data buffer 245 are output to the first control unit 23 in a wake-up state after a predetermined BLE procedure. Here, the data buffer 245 temporarily stores the signal data demodulated by the demodulator 244 when the first control unit 23 is in standby mode. The first communication circuit 24 outputs the signal data stored in the data buffer 245 to the first control unit 23 if, for example, the signal data demodulated by the demodulator 244 matches the wake-up signal described later. The first communication circuit 24 discards the signal data stored in the data buffer 245 if the signal data demodulated by the demodulator 244 does not match the wake-up signal described later. Note that the signal data demodulated by the demodulator 244 is not always stored in the data buffer 245. For example, the first communication circuit 24 may output the signal data demodulated by the demodulator 244 after the first control unit 23 has been started up to the first control unit 23 without storing it in the data buffer 245. Furthermore, the first communication circuit 24 may not store the signal data demodulated by the demodulator 244 in the data buffer 245 and may not output it to the first control unit 23 if, for example, the demodulated signal data is a dedicated signal for activating the first control unit 23. Note that the data buffer is not a mandatory configuration and may be omitted if, for example, the in-vehicle unit 3 is configured to transmit the same signal multiple times.

[0038] The startup unit 27 starts up the first control unit 23. In this embodiment, the startup unit 27 switches the communication mode of the first control unit 23 from standby to wake-up based on the digital signal converted by the digital converter 243. The startup unit 27 includes a matching unit 271 and a switching unit 272.

[0039] As shown in Figure 4, when the matching unit 271 receives a wireless signal compliant with the BLE communication standard emitted by an external device such as the in-vehicle unit 3, it compares the digital signal corresponding to the signal with a matching pattern corresponding to the wake-up signal. This matching pattern corresponds to at least a portion of the wake-up signal emitted by the external device such as the in-vehicle unit 3 and is stored in memory in advance. When the matching unit 271 receives a wake-up signal from an external device such as the in-vehicle unit 3, it compares the wake-up signal with the matching pattern and outputs a signal indicating whether or not they match as the matching result to the switching unit 272.

[0040] The switching unit 272 switches the first control unit 23 to the wake-up state according to the matching result in the matching unit 271. For example, if the matching result in the matching unit 271 shows a match, the switching unit 272 turns on the connection between the demodulator 244 and the data buffer 245 and the configuration that performs the BLE connection work, thereby starting up the first control unit 23. If the matching result in the matching unit 271 shows a mismatch, the switching unit 272 keeps the connection between the demodulator 244 and the data buffer 245 and the configuration that performs the BLE connection work off.

[0041] Returning to Figure 2, the battery 25 supplies power to the sensing unit 21, the first control unit 23, and other components. Power supplied from the battery 25 enables the sensing unit 21 to collect data on tire pressure and the first control unit 23 to perform various calculations. The battery 25 is composed of a dischargeable primary battery.

[0042] The tire sensor 2 configured in this way is attached to the air injection valve on the wheel of each wheel 6a to 6d, and the sensing unit 21 is positioned so that it is exposed on the inside of the tire. As a result, the tire sensor 2 detects the tire pressure and transmits a frame containing tire information indicating the detection result.

[0043] Next, the general configuration of the in-vehicle unit 3 will be explained with reference to Figure 5. As shown in Figure 5, the in-vehicle unit 3 includes a second communication antenna 31, a second communication circuit 32, a power supply control unit 33, and a second control unit 34.

[0044] The second communication antenna 31 is an antenna for communicating with each tire sensor 2 via BLE. The second communication antenna 31 may be an internal antenna located inside the main body of the vehicle-mounted unit 3, or it may be an external antenna with wiring extended from the main body.

[0045] The second communication circuit 32 is a circuit that performs BLE communication with each tire sensor 2 via the second communication antenna 31. The second communication circuit 32 transmits and receives wireless signals conforming to the BLE communication standard via the second communication antenna 31. The second communication circuit 32 is capable of unidirectional communication from the in-vehicle unit 3 to the tire sensor 2 and bidirectional communication between the tire sensor 2 and the in-vehicle unit 3. The second communication circuit 32 has a circuit configuration that corresponds to the communication method adopted in BLE communication.

[0046] The power control unit 33 supplies power to each part of the in-vehicle unit 3 based on the power supply from the battery 8, specifically, a predetermined voltage (+B) applied from the battery 8. Based on the power control by the power control unit 33, the in-vehicle unit 3 operates, and BLE communication and tire pressure detection by the second control unit 34 are performed. The power control unit 33 generates power to the drive based on the control signal from the second control unit 34. Basically, the power control unit 33 stops generating power to the drive when the ignition switch is turned off, and generates power to the drive when the ignition switch is turned on. The battery 8 is composed of a rechargeable secondary battery. The battery 8 is charged, for example, by regenerative energy during braking of the vehicle 1.

[0047] The second control unit 34 is composed of a microcomputer equipped with a CPU, memory such as ROM and RAM, I / O, etc. The second control unit 34 performs predetermined processes such as communication processing, tire pressure detection processing, and auto-location processing according to a program stored in the internal memory.

[0048] The communication process involves wireless communication with each tire sensor 2. The second control unit 34 causes the second communication circuit 32 to start and stop receiving. Below, an example of the communication process performed by the second control unit 34 will be described with reference to Figure 6. The control routine shown in Figure 6 is executed periodically or irregularly by the second control unit 34.

[0049] As shown in Figure 6, in step S10, the second control unit 34 determines whether or not a wire connection to the tire sensor 2 is necessary. Scenarios in which a wire connection to the tire sensor 2 is necessary include, for example, when performing tire pressure detection processing or auto location processing, or when performing abnormality diagnosis at a vehicle factory or vehicle dealer. If a communication connection to the tire sensor 2 is necessary (S10: YES), the second control unit 34 executes a communication connection process in step S20 to establish a communication connection with the tire sensor 2. The BLE communication connection process between the tire sensor 2 and the in-vehicle unit 3 will be described later.

[0050] In the tire pressure detection process, the second control unit 34 detects the tire pressure of the wheels 6a to 6d to which each tire sensor 2 is attached. Specifically, the second control unit 34 detects the tire pressure by performing calculations based on the tire information stored in the frame received by the second communication circuit 32. It then outputs an electrical signal corresponding to the detected tire pressure to the display device 4. The second control unit 34 also compares the detected tire pressure with a predetermined alarm threshold Th, and if it detects that the tire pressure has fallen below the predetermined alarm threshold Th, it outputs a signal to that effect to the display device 4. In this way, the second control unit 34 issues an alarm to inform the user that the tire pressure has dropped.

[0051] The auto-location process automatically associates tire information from each tire sensor 2 with the position of each wheel 6a to 6d. For example, the second control unit 34 determines which of the wheels 6a to 6d each tire sensor 2 is attached to based on the signal strength of the wireless signal received from each tire sensor 2, the arrival time of the wireless signal between each tire sensor 2 and the on-board unit 3, etc.

[0052] The maintenance tool 5, although not shown in the diagram, includes diagnostics for checking for abnormalities in various on-board equipment, as well as antennas and communication circuits for wireless communication with each tire sensor 2 and on-board unit 3. The maintenance tool 5 is capable of performing the same communication processing as the on-board unit 3. Situations where wiring connection between the maintenance tool 5 and the tire sensors 2 is necessary include, for example, situations where abnormality diagnosis, tire replacement, and tire rotation are performed at vehicle factories or vehicle dealerships.

[0053] Next, the connection process for BLE communication between the tire sensor 2 and the in-vehicle unit 3 will be explained with reference to Figures 3, 7, and 8. When the in-vehicle unit 3 requires communication with the tire sensor 2, it sends a wake-up signal to the tire sensor 2 in order to switch the tire sensor 2's communication mode to the wake-up state. In this embodiment, as shown in Figure 7, the in-vehicle unit 3 sends an advertised signal as a wake-up signal to the tire sensor 2.

[0054] The frame structure of the advertised signal, as shown in Figure 8, consists of a preamble, access address, PDU, and CRC. The PDU consists of a header and a payload. The header contains device information specific to the in-vehicle unit 3. PDU stands for Protocol Data Unit, and CRC stands for Cyclic Redundancy Check.

[0055] When the tire sensor 2 receives a wireless signal from the in-vehicle unit 3, the activation unit 27 of the first communication circuit 24 compares the wireless signal with a matching pattern corresponding to the wake-up signal. The matching pattern includes at least a portion of the advertised signal, which is the wake-up signal. Specifically, the matching pattern includes information up to the preamble, access address, and PDU header of the advertised signal, so as to be able to identify the in-vehicle unit 3. To improve the accuracy of the matching, it is desirable that the matching pattern includes information from the preamble to the CRC.

[0056] If the matching result from the matching unit 271 of the starting unit 27 indicates a match between the wireless signal and the matching pattern, the tire sensor 2 switches the first control unit 23 to the wake-up state. This returns the tire sensor 2, which is in a power-saving state, to a normal state in which it can perform various functions. When the first control unit 23 of the tire sensor 2 is in the wake-up state, the tire sensor 2 becomes capable of broadcasting an advertisement signal. The tire sensor 2 may broadcast an advertisement signal when the first control unit 23 is in the wake-up state, or it may perform an operation other than broadcasting an advertisement signal.

[0057] After emitting a wake-up signal, the in-vehicle unit 3 performs a scan process at predetermined intervals to scan for advertised signals. When the in-vehicle unit 3 scans for advertised signals emitted by the tire sensor 2, it requests a connection to the tire sensor 2 and establishes a connection with the tire sensor 2.

[0058] In this way, the TPMS enables the connection process for BLE communication between the tire sensor 2 and the in-vehicle unit 3. In this embodiment, the connection process for BLE communication between the tire sensor 2 and the maintenance tool 5 is implemented in the same manner as the connection process for BLE communication between the tire sensor 2 and the in-vehicle unit 3.

[0059] Here, BLE communication can also be achieved by periodically activating the first control unit 23 of the tire sensor 2 to broadcast an advertisement signal, and then the in-vehicle unit 3 scans the advertisement signal to form a connection.

[0060] However, with this type of communication connection, the tire sensor 2 needs to activate the first control unit 23 periodically to broadcast the advertised signal, which increases power consumption. This shortens the lifespan of the tire sensor 2. Also, the in-vehicle unit 3 cannot determine the timing of when the tire sensor 2 emits the advertised signal, and it takes time to establish a connection, resulting in poor responsiveness.

[0061] Furthermore, BLE communication can also be achieved by periodically broadcasting an advertisement signal from the in-vehicle unit 3, and periodically activating the first control unit 23 of the tire sensor 2 to scan the advertisement signal and form a connection.

[0062] However, with this type of communication connection, the tire sensor 2 needs to activate the first control unit 23 periodically to scan for advertised signals, which increases power consumption. Also, if the scanning period for advertised signals in the tire sensor 2 is increased to reduce power consumption, the responsiveness decreases.

[0063] In contrast to these, in this embodiment, when the tire sensor 2 receives a wireless signal in a frequency band conforming to the BLE communication standard emitted by the in-vehicle unit 3 while the first control unit 23 is in standby mode, it compares the wireless signal with a matching pattern corresponding to the wake-up signal. Then, the tire sensor 2 switches the first control unit 23 to the wake-up state according to the matching result.

[0064] As described above, the TPMS of this embodiment is configured such that the first control unit 23 of the tire sensor 2 switches from standby to wake-up state upon receiving a wake-up signal emitted by the in-vehicle unit 3. This eliminates the need to intermittently activate the first control unit 23 of the tire sensor 2 when communication is established between the tire sensor 2 and the in-vehicle unit 3, thereby suppressing the power consumption of the tire sensor 2. Furthermore, since the wake-up signal emitted by the in-vehicle unit 3 is a wireless signal in a frequency band compliant with the BLE communication standard, there is no need to add a dedicated antenna to the tire sensor 2 to receive the wake-up signal.

[0065] Therefore, the wireless communication system and wireless communication equipment of this embodiment applied to TPMS can suppress power consumption while keeping the complexity of the communication configuration under control. Furthermore, the current consumption of the tire sensor 2 in standby mode is in the μA range, which is significantly smaller than the current consumption (several mA) required to emit advertising signals or scan.

[0066] Furthermore, the wireless communication system and wireless communication equipment of this embodiment applied to TPMS have the following features.

[0067] (1) The in-vehicle unit 3 transmits an advertisement signal as a wake-up signal to the tire sensor 2. The activation unit 27 of the tire sensor 2 includes a matching unit 271 that matches at least a portion of the advertisement signal transmitted by the in-vehicle unit 3 with a matching pattern, and a switching unit 272 that switches the first control unit 23 to the wake-up state according to the matching result of the matching unit 271. In this way, if the wake-up signal is an advertisement signal modulated using the GFSK modulation method, the tire sensor 2 can receive and demodulate the wake-up signal with its existing configuration (various configurations for BLE communication), thus simplifying the communication configuration. Another advantage is that, because the advertisement signal conforms to the BLE protocol, it is possible to add transmission information, including the purpose of the communication connection, to the PDU.

[0068] (2) When the tire sensor 2 receives a wake-up signal from the on-board unit 3 and the first control unit 23 enters a wake-up state, it becomes capable of broadcasting an advertisement signal. In other words, when the tire sensor 2 receives a wake-up signal from the on-board unit 3, the first control unit 23 of the tire sensor 2 is activated and becomes capable of broadcasting an advertisement signal. This allows for a significant reduction in the power consumption of the tire sensor 2 compared to a configuration in which the first control unit 23 of the tire sensor 2 is activated intermittently.

[0069] (3) The tire sensor 2 detects the tire pressure of the wheels 6a to 6d mounted on the vehicle 1. The on-board unit 3 is installed on the vehicle 1 and monitors for any abnormalities in tire pressure based on the detection results from the tire sensor 2. This allows for a simplified communication connection between the tire sensor 2 and the on-board unit 3, while also suppressing the power consumption of the tire sensor 2 and extending its lifespan. In particular, since replacing the battery in the tire sensor 2 tends to be a complicated task, the ability to suppress power consumption is of great significance.

[0070] (4) The battery 25 of the tire sensor 2 is a primary battery that can be discharged. In such a configuration, it is of great importance to suppress power consumption and extend the lifespan.

[0071] (5) Use cases for a configuration that enables a wake-up operation with low power consumption of the tire sensor 2 include the following: use in vehicle factories and dealerships, inquiries from the on-board unit 3 to the tire sensor 2 during normal operation, start instructions for auto location, when it is desirable to reduce the battery size 25, and acquiring only the necessary amount in real time when checking on-demand pressure while parked. The same applies to the second embodiment.

[0072] (Second Embodiment) Next, the second embodiment will be described with reference to Figures 9 to 11. In this embodiment, the differences from the first embodiment will be mainly described.

[0073] As shown in Figure 9, the in-vehicle unit 3 of this embodiment transmits a 2.4GHz high-frequency signal, different from the advertised signal, to the tire sensor 2 as a wake-up signal. Unlike the first embodiment, the second communication circuit 32A of the in-vehicle unit 3 includes a circuit 321 that transmits a high-frequency signal modulated with a modulation scheme different from GFSK. The second communication circuit 32A of this embodiment is capable of transmitting a high-frequency signal modulated with an OOK modulation scheme. Note that the modulation scheme may be ASK modulation, which is different from OOK modulation.

[0074] The high-frequency signal that constitutes the wake-up signal has a smaller data size than the advertisement signal. The high-frequency signal can be composed of a 2-byte frame, for example, as shown in Figure 10. Note that the high-frequency signal that constitutes the wake-up signal may differ from that shown in Figure 10, as long as it has a smaller data size than the advertisement signal.

[0075] The tire sensor 2 in this embodiment is configured to receive a high-frequency signal in the 2.4GHz band that constitutes the wake-up signal. As shown in Figure 11, the first communication circuit 24A of the tire sensor 2 includes a low-noise amplifier 241, a phase-locking circuit 242, a digital converter 243, a demodulator 244, a data buffer 245, a startup unit 27A, and a WUP circuit 28.

[0076] The WUP circuit 28 is a dedicated receiving circuit for receiving high-frequency signals in the 2.4 GHz band that constitute the wake-up signal. The WUP circuit 28 is configured to perform demodulation corresponding to the signal modulation scheme in the in-vehicle unit 3.

[0077] The WUP circuit 28 includes a low-pass filter (LPF) 281, a comparator (CMP) 282, a sample-and-hold circuit (S / H) 283, an RC oscillator (RC-OSC) 284, and a shift register 285. The WUP circuit 28 amplified the received signal from the first communication antenna 26 using a low-noise amplifier 241, passed the signal through the low-pass filter 281, and then compared it with a voltage signal Vref conforming to the OOK modulation scheme using the comparator 282. The signal output from the comparator 282 is then used with the sample-and-hold circuit 283 and the RC oscillator 284 to store the desired signal in the shift register 285.

[0078] The startup unit 27A compares the signal stored in the shift register 285 with the matching pattern corresponding to the wake-up signal and switches the first control unit 23 to the wake-up state according to the matching result. The startup unit 27A includes a matching unit 271A and a switching unit 272A. The matching unit 271A compares the signal stored in the shift register 285 with the matching pattern corresponding to the wake-up signal and outputs a signal indicating whether or not they match as the matching result to the switching unit 272A. The switching unit 272A switches the first control unit 23 to the wake-up state according to the matching result in the matching unit 271A. For example, if the matching result in the matching unit 271A indicates a match, the switching unit 272A switches the first control unit 23 to the wake-up state. The first control unit 23 activates the configuration for receiving the advertisement signal (phase-lock circuit 242, digital converter 243, demodulator 244, data buffer 245, etc.) at startup.

[0079] Other aspects are the same as in the first embodiment. The wireless communication system and wireless communication equipment of this embodiment can obtain the same effects as in the first embodiment, which are achieved from a configuration common to or equivalent to that of the first embodiment.

[0080] Furthermore, the wireless communication system and wireless communication equipment of this embodiment applied to TPMS have the following features.

[0081] (1) The in-vehicle unit 3 transmits a high-frequency signal in the 2.4GHz band, different from the advertisement signal, as a wake-up signal to the first device. The activation unit 27A of the tire sensor 2 includes a matching unit 271A that matches the high-frequency signal emitted by the in-vehicle unit 3 with a matching pattern, and a switching unit 272A that switches the first control unit 23 to the wake-up state according to the matching result of the matching unit 271A. In this way, if the wake-up signal is a high-frequency signal in the 2.4GHz band other than the advertisement signal, it can be received by the first device with an existing antenna, so the complexity of the communication configuration can be reduced compared to when receiving an LF signal, etc.

[0082] (2) The in-vehicle unit 3 transmits a high-frequency signal with a smaller data volume than the advertisement signal as a wake-up signal. This reduces the power consumption required for receiving and matching the wake-up signal in the tire sensor 2 compared to when the advertisement signal is used as the wake-up signal.

[0083] (Modified version of the second embodiment) As in the second embodiment, it is desirable that the in-vehicle unit 3 emits a high-frequency signal with a smaller data amount than the advertised signal as a wake-up signal, but this is not required.

[0084] (Other embodiments) While typical embodiments of this disclosure have been described above, this disclosure is not limited to the embodiments described above and can be modified in various ways, for example, as follows.

[0085] The TPMS in the above-described embodiment is configured such that the tire sensor 2 switches to the wake-up state in response to a wake-up signal emitted by the in-vehicle unit 3, but it is not limited to this configuration. The TPMS may also be configured such that the tire sensor 2 switches to the wake-up state in response to a wake-up signal emitted by an external device such as a maintenance tool 5.

[0086] In the above-described embodiment, the tire sensor 2 broadcasts an advertisement signal when the first control unit 23 enters a wake-up state after receiving a wake-up signal from an external device such as an in-vehicle unit 3, but it is not limited to this. The tire sensor 2 may also transmit a signal other than the advertisement signal (for example, a signal containing tire information) when the first control unit 23 enters a wake-up state.

[0087] The embodiments described above illustrate examples of applying the wireless communication system and wireless communication equipment of this disclosure to a TPMS, but the invention is not limited thereto. The wireless communication system and wireless communication equipment of this disclosure can also be applied to communication systems between portable terminals such as smart keys and in-vehicle equipment. Furthermore, the wireless communication system and wireless communication equipment of this disclosure are not limited to mobile objects such as vehicles, but can also be applied to communication systems used in, for example, houses, factories, etc.

[0088] In the embodiments described above, it goes without saying that the elements constituting the embodiments are not necessarily essential, except in cases where they are explicitly stated to be essential or where they are clearly considered essential in principle.

[0089] In the embodiments described above, if numerical values ​​such as the number, numerical values, quantities, or ranges of the components of the embodiment are mentioned, the embodiment is not limited to those specific numbers unless explicitly stated as particularly essential or clearly limited to a specific number in principle.

[0090] In the embodiments described above, when referring to the shape, positional relationships, etc. of the components, the definition is not limited to those shapes, positional relationships, etc., unless otherwise specifically stated or when the definition is fundamentally limited to a particular shape, positional relationship, etc.

[0091] The control unit and its method of this disclosure may be implemented in a dedicated computer provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program. The control unit and its method of this disclosure may be implemented in a dedicated computer provided by configuring a processor by one or more dedicated hardware logic circuits. The control unit and its method of this disclosure may be implemented in one or more dedicated computers configured by a combination of a processor and memory programmed to perform one or more functions and a processor configured by one or more hardware logic circuits. The computer program may also be stored as instructions executed by the computer on a computer-readable non-transitional tangible recording medium. [Explanation of Symbols]

[0092] 2. Tire sensor (first device) 23. First Control Unit (Control Unit) 24. First communication circuit (communication circuit) 27, 27A starting section 3. In-vehicle unit (second device) 5. Maintenance Tools (Second Equipment)

Claims

1. A wireless communication system, A first device (2) that operates using a battery (25) as a power source and has a control unit (23) that can switch the communication mode between a standby state and a wake-up state, The system includes a second device (3, 5) which is configured to perform wireless communication in accordance with the BLE communication standard with the first device, and which, upon receiving an advertisement signal from the first device, can request a connection from the first device and establish a connection with the first device. The first device includes a startup unit (27, 27A) that, when the control unit is in the standby state, receives a wireless signal in a frequency band conforming to the BLE communication standard emitted by the second device, compares the wireless signal with a matching pattern corresponding to a wake-up signal, and switches the control unit to the wake-up state according to the matching result. The second device transmits the advertised signal as the wake-up signal to the first device. The activation unit (27) is a wireless communication system comprising: a matching unit (271) that matches at least a portion of the advertised signal emitted by the second device with the matching pattern; and a switching unit (272) that switches the control unit to the wake-up state according to the matching result in the matching unit.

2. The wireless communication system according to claim 1, wherein the first device receives the wake-up signal from the second device and the control unit enters the wake-up state, and then enters a state where it can broadcast the advertised signal.

3. The first device is a tire sensor (2) that detects the tire pressure of a wheel mounted on a vehicle. The wireless communication system according to claim 1 or 2, wherein the second device is an in-vehicle unit (3) installed in the vehicle and monitoring for abnormalities in tire pressure based on the detection results from the tire sensor.

4. The wireless communication system according to claim 1 or 2, wherein the battery is a primary battery capable of discharge.

5. A wireless communication device that operates using a battery (25) as a power source, A control unit (23) that can switch the communication mode between standby and wake-up states, A communication circuit (24) that performs wireless communication in accordance with the BLE communication standard with external devices (3, 5), and establishes a connection with the external devices upon connection request from the external devices, The system includes a startup unit (27) that, when the control unit is in the standby state, receives a wireless signal in a frequency band conforming to the BLE communication standard, compares the wireless signal with a matching pattern corresponding to the wake-up signal, and switches the control unit to the wake-up state according to the matching result. The external device is configured to transmit an advertised signal as the wake-up signal. The activation unit (27) includes a matching unit (271) that matches at least a portion of the advertised signal emitted by the external device with the matching pattern, and a switching unit (272) that switches the control unit to the wake-up state according to the matching result in the matching unit, in a wireless communication device.

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