Wireless sensor

Abstract

To provide a small-sized and highly reliable wireless sensor that can be used for safe operation of an aircraft and can wirelessly transmit acquired sensor data.SOLUTION: A wireless sensor 10 used for an aircraft includes elements 20 related to sensing operation, a power supply unit 25 related to power supply to the elements 20, and a transmission / reception antenna unit 24. The elements 20 and the power supply unit 25 are three-dimensionally built-in in a multilayer printed wiring board and integrally sealed with a printed wiring board material. The power supply unit 25 is an all-solid-state battery. The wireless sensor continuously performs sensing using the built-in all-solid-state battery even in environment with less light, vibration, and temperature difference in which a power generation element in the aircraft is difficult to use.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a small power-saving wireless sensor for preventing aircraft accidents that performs wireless data transmission and reception.

Background Art

[0002] In recent years, due to the increasing popularity of the Internet of Things (IoT), the scale of the sensor market has been rapidly expanding. There is an increasing demand to utilize various sensors such as temperature, humidity, pressure, vibration, acceleration, sound, light, flow rate, speed, and GPS for data analysis and utilization. It is also said that the use of sensors will increase rapidly in the future for applications such as safety confirmation and automation.

[0003] However, existing sensor devices have not advanced much in terms of low power consumption, and in many cases, they are wired for power supply. Therefore, wiring installation requires cost and time, and as the scale increases, the workload of replacing or rerouting the wiring becomes larger, and there are also problems such as difficulty in repair.

[0004] By the way, for vehicles such as airplanes, obtaining sensor data during operation for the purpose of safe operation and accident prevention has been considered. However, when using sensors that require wiring, as the number of sensors used increases, the wiring weight increases, resulting in an increase in the overall weight of the aircraft. Furthermore, in order to prevent problems due to crosstalk, it is necessary to take measures such as using shielded wires for the signal lines of the sensors, and thus the problem of weight increase becomes more prominent.

[0005] On the other hand, efforts have been made to place sensors on important parts of aircraft engines and share sensor information during flight between sensor manufacturers and aircraft manufacturers, who are their customers, through satellite communication networks, so that aircraft companies can generate profits through early repair. In order to obtain information necessary for aircraft safety management, it is desired to install a large number of sensors at multiple locations. However, due to the problem of weight increase, the above efforts are limited in their scope of use.

[0006] Of course, it is also possible to make it wireless using a battery. However, the larger the capacity of the battery, the larger its size, making it difficult to miniaturize the product and causing another problem of restricted mounting locations. Also, in existing sensor devices with high power consumption, frequent battery replacement is necessary, and problems such as increased replacement operation costs and the environmental burden of battery waste cannot be ignored.

[0007] Moreover, when considering its use in an aircraft, the battery also has safety concerns such as the possibility of rupture and ignition. Furthermore, for accident prevention, locations where sensor measurements are required, such as the tips of the main wings and tail wings, can be considered. However, battery replacement becomes difficult in such narrow and intricate locations.

[0008] Furthermore, many existing sensor devices have multiple types of components surface-mounted. The exposed component locations are likely to cause a decrease in reliability due to external factors such as humidity and dust, and are not suitable for use in applications that require environmental resistance such as aircraft. To enhance environmental resistance, it can be housed in a rugged case, but this brings conflicting problems such as an increase in product size and weight.

[0009] Instead of using a battery, a method of wirelessly transmitting power can also be considered. However, the attenuation when transmitting the electromotive force through space is large, and a large amount of power needs to be transmitted to activate the sensor device. Therefore, it cannot be used in an environment such as an aircraft where there is a risk of radio interference. Also, when trying to activate a large number of sensor devices by wireless power transmission, the situation of radio waves overflowing in space will occur, and it is considered that it will reach a level where health hazards to the human body (radio wave pollution, digital poisoning) cannot be ignored, which becomes a problem in terms of use.

[0010] Due to the above circumstances, the management of parts and the airframe on an aircraft remains limited to recording and managing the maintenance history as traceability information in RFID tags, and is not capable of monitoring anomalies during operation with a sufficient number of sensors for preventing failures and accidents. On the other hand, if anomalies such as abnormal sounds, abnormal vibrations, heat generation, pressure anomalies, oil leaks, and water leaks during operation can be detected by sensors, it becomes possible to detect toughness fatigue, wear, oil depletion, airtightness anomalies, malfunction, and other anomalies that are difficult to notice during maintenance at an early stage, and prevent the occurrence of major accidents.

[0011] Also, if a sufficient amount of sensor data can be collected and analyzed to identify differences from when it is stationary as early signs, it can lead to prompt accident prevention measures based on the judgment of the in-flight computer during flight, or in cases where it is difficult to take measures during flight, it can lead to a judgment to make an emergency landing. Furthermore, it becomes possible to greatly contribute to safe operation by indicating parts replacement and maintenance locations during maintenance or by using them to identify the cause of an accident.

[0012] As a countermeasure for the above problems, Patent Document 1 (Japanese Patent Application Laid-Open No. 2008-544730) discloses an apparatus including a core device that utilizes RF power harvesting as a power source and has various sensors (including sensors for aircraft). Further, Patent Document 2 (Japanese Patent Application Laid-Open No. 2012-507254) discloses a power control system including an energy harvester that can be used for transportation means such as aircraft and can supply power to sensors. Further, Patent Document 3 (Japanese Patent Application Laid-Open No. 2019-515405) discloses a transportation tracking system using an electronic tag including an electric energy generator, which is attached to an aircraft, an engine, a power supply device, in-aircraft devices, etc. Further, Patent Document 4 (Japanese Patent Application Laid-Open No. 2020-525928) discloses an energy harvesting RFID circuit that can be used for health monitoring of pipe joints of structures such as pipelines, bridges, ships, and aircraft. Further, Patent Document 5 (Japanese Patent Application Laid-Open No. 2020-521223) discloses a wireless sensor assembly operating with an energy harvester for the purpose of preventing fire accidents caused by lithium-ion batteries in the cabin storage shelves of aircraft. Further, Patent Document 6 (Japanese Patent Application Laid-Open No. 2020-522422) discloses a wireless gas sensor including an energy harvester.

Prior Art Documents

Patent Documents

[0013]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Summary of the Invention

Problems to be Solved by the Invention

[0014] However, in the technology disclosed in Patent Document 1, since RF power harvesting collects weak radio waves from the surrounding environment, it requires a relatively large antenna, making miniaturization difficult and making it difficult to use inside an aircraft. Also, when providing a dedicated power transmitter to operate RF power harvesting, there is a concern that it may cause radio wave interference to the existing aircraft operation system due to the large electromotive force transmission. In the technology disclosed in Patent Document 2, the power supply part can be made wireless by using an energy harvester, but the wireless connection with other devices such as sensors is not explicitly stated, and the increase in wiring weight due to wired use remains an issue. In the technology disclosed in Patent Document 3, the power consumption of the sensor has not been reduced, and it is only used for managing simple numerical information such as the number of operating cycles and the number of aircraft flights. That is, there has been a problem that it cannot perform complex processes such as collecting sensor information from tags and utilizing the sensor values for the safe operation management of an aircraft. In the technology disclosed in Patent Document 4, the sensor operates while suppressing power consumption by functioning only while being read by an RFID reader. Therefore, it has not been possible to continuously acquire sensor data of the object during operation, and there has been a problem that it is not suitable for applications such as aircraft operation management. Also, although a method of enhancing reliability by sealing the RFID tag inside the housing is presented, there are concerns such as moisture intrusion due to pinholes or seal defects, and the seal may be damaged if the heat resistance and impact resistance of the housing are insufficient, which becomes an issue in applications that require high reliability such as aircraft. Also, due to the relationship of housing the product inside later, there has been a problem that the product size becomes slightly larger. In the technology disclosed in Patent Document 5, the sensor assembly is a fairly large one for the passenger cabin storage shelf, and there has been a problem that it is difficult to use for parts management and measurement applications inside the narrow aircraft fuselage.Although there is no clear indication of the power generation method of the energy harvester, utilization methods that require relatively large amounts of power, such as using a light-emitting diode for display or measuring in milliseconds using a gas sensor, have been presented. There was a problem in that the minute power of the energy harvester was insufficient and there was a concern that the operation would become unstable. In the technology disclosed in Patent Document 6, a gas sensor and a pump that sends air to the gas sensor are operated by using a battery and an energy harvester as power sources. However, when using a battery, there are risks such as fire, rupture, and liquid leakage, so there was a problem in using it for an aircraft that requires reliability.

Means for Solving the Problems

[0015] Therefore, the present invention has been made to solve the above problems, and an object thereof is to provide a wireless sensor that can be used for the safe operation of an aircraft, is small, has high reliability, can operate with low power consumption, and can wirelessly transmit the acquired sensor data.

[0016] The present invention solves the above problems by means of the following solution described as one embodiment.

[0017] The wireless sensor according to the present invention is a wireless sensor used in an aircraft, and includes elements related to a sensing operation, a power supply unit for supplying power to the elements, and a transmission / reception antenna unit. The elements and the power supply unit are three-dimensionally built in a multilayer printed wiring board and integrally sealed with a printed wiring board material. The power supply unit is an all-solid-state battery, and continuously performs sensing using the built-in all-solid-state battery even in an environment with little light, vibration, and temperature difference where it is difficult for power generation elements in the aircraft to be used.

[0018] Since the element group and the power supply unit are built in a sealed structure within a multilayer printed wiring board, the wireless sensor can be miniaturized, its environmental resistance can be increased, and high reliability can be obtained. Furthermore, by providing a transmission / reception antenna unit, the acquired sensor data can be wirelessly transmitted. Therefore, the wireless sensor can be used for the safe navigation of an aircraft.

[0019] Also, the all-solid-state battery is characterized in that it is configured to be rechargeable during maintenance using contactless power supply. According to this configuration, continuous sensing can be performed.

[0020] Also, the element group includes a sensor unit that acquires predetermined sensor data, a control unit that executes calculation, digitization, and overall operation management of the sensor data, and a transmission / reception unit that externally communicates the data obtained by the sensor unit, and the power supply unit further has a voltage control element. Thereby, not only acquisition of sensor data and wireless transmission of the sensor data but also a series of operations of sensing, calculation / digitization, and wireless communication become possible.

[0021] By using these configurations, a wireless sensor that is small, highly reliable, and can be used without being limited by location is realized, and data collection using a large number of sensors during the operation of an aircraft becomes possible. In addition, phenomena such as toughness fatigue, microcracks, fuel exhaustion, abnormal sounds, abnormal vibrations, heat generation, pressure abnormalities, oil / water leakage due to component wear and tear, which were difficult to detect in conventional aircraft body inspections and traceability management in a stationary state, can be collected as sensor data during operation, and it becomes possible to prevent major accidents of the aircraft.

Effects of the Invention

[0022] According to the present invention, it is possible to provide a wireless sensor that can be used for the safe operation of an aircraft, is small and highly reliable, and can wirelessly transmit the acquired sensor data.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0024] First, the wireless sensor 10 in the present embodiment will be described. In the present embodiment, the surface of the transmission / reception antenna unit 24 in FIG. 1 having the antenna is referred to as the upper surface, and the back surface thereof is referred to as the lower surface. However, since the wireless sensor 10 is assumed to be used by attaching the lower surface to a predetermined measurement object 40 or a predetermined measurement location, the vertical direction of the wireless sensor 10 does not necessarily coincide with the vertical direction with the ground side facing downward. Further, as an example, the wireless sensor 10 has six metal layers 14 laminated, but the number of metal layers 14 is not limited to six layers. For the metal layer 14, for convenience, it may be referred to as the first metal layer, the second metal layer, the third metal layer, the fourth metal layer, the fifth metal layer, and the sixth metal layer in the direction from the upper surface side to the lower surface side. Further, as an example, the multilayer printed wiring board 12 has five printed wiring board materials (which may be referred to as insulating layers) 12 laminated, but the total number of insulating layers 12 is not limited to five layers. For the insulating layer 12, for convenience, it may be referred to as the first insulating layer, the second insulating layer, the third insulating layer, the fourth insulating layer, and the fifth insulating layer in order from the upper surface side to the lower surface side.

[0025] Further, the wireless sensor 10 in the present embodiment is assumed to be used for aircraft applications. More specifically, the wireless sensor 10 can be provided inside the fuselage, inside the main wing, inside the tail wing, etc., but is not limited thereto.

[0026] Subsequently, the wireless sensor 10 in the present embodiment will be described based on each drawing. Note that the wireless sensor 10 of the present invention is not limited to the following embodiments.

[0027] <Wireless Sensor> <<Overall Configuration>> As shown in Fig. 1, the wireless sensor 10 has a configuration in which elements 20 related to the sensing operation and a power supply unit 25 for supplying power to the elements 20 are integrally sealed in a multilayer printed wiring board 12 and three-dimensionally incorporated. Further, the wireless sensor 10 includes a transmission / reception antenna unit 24. That is, as shown in Fig. 1, the wireless sensor 10 has a configuration including parts 21 to 23 as elements 20, a power supply unit 25, a transmission / reception antenna unit 24, a metal layer 14, a through hole 16, and an insulating layer 12.

[0028] With the above configuration, miniaturization of the product can be achieved as compared with the case of surface-mounting the elements 20 and the power supply unit 25.

[0029] In addition, since parts 21 to 23 as elements 20 to be incorporated and the power supply unit 25 are integrally formed by the printed wiring board material 12, compared with a product having a structure covered with a lid or the like in a post-process, it is possible to make it less susceptible to the influence of the external environment such as humidity and dust without cavities, and it can be made into a product that can be safely used even in applications that require high reliability such as an aircraft.

[0030] Furthermore, in a planar component arrangement like a surface-mount product, the wiring between components tends to be redundant. However, in the present invention, since the layer between the multilayer boards can be used to shorten the wiring length, it is possible to improve the electrical characteristics while miniaturizing the product. In particular, the wiring length has a great influence in the high-frequency region, and it is possible to improve the characteristics of wireless communication and enhance the reliability of wireless data communication. Furthermore, by miniaturizing the wireless sensor 10, it can be easily arranged in narrow or intricate locations such as the tip of the wing inside the aircraft 60.

[0031] <<Metal Layer>> Note that the metal layer 14 is formed as a wiring pattern made of copper.

[0032] <<Through Hole>> In addition, the through-hole 16 is formed by performing copper plating on the through-hole in the manufacturing process of the multilayer printed wiring board. The method of electrically connecting the metal layer 14 is not limited to through-holes, and may be formed by build-up connection using laser vias, end face electrodes, paste vias filled with conductive paste in laser vias, or a combination thereof.

[0033] <<Printed Wiring Board Material (Insulating Layer)>> In addition, as the material used for the printed wiring board material 12, a printed wiring board material 12 such as epoxy is used, but other resins may be used, or a combination of multiple resins may be used.

[0034] <<Soldermask>> In addition, it is preferable that a soldermask for insulation and protection is applied to the upper and lower surfaces (front and back surfaces) of the wireless sensor 10. However, the material for insulation and protection is not limited to the soldermask, and other insulating materials or the like may be used.

[0035] <<Elements>> In addition, as described above, as shown in FIG. 2, the elements 20 include a sensor unit 21 that acquires predetermined sensor data and a transmission / reception unit 23 that transmits and receives (i.e., external communication) the sensor data via a transmission / reception antenna unit 24.

[0036] <<Sensor Unit>> The sensor unit 21 is disposed inside the second insulating layer 12 as an example, and is connected to the transmission / reception unit 23 and the power supply unit 25 via the metal layer 14 and the through-hole 16. As will be described later, when the wireless sensor 10 has a control unit 22, the sensor unit 21 is also connected to the control unit 22.

[0037] Further, as an example, the sensor unit 21 can be at least one or more of sensors such as a temperature sensor that measures temperature changes, an acceleration sensor that measures acceleration changes, a humidity sensor that measures humidity changes, a pressure sensor that measures pressure changes, a magnetic sensor that measures magnetic changes, a light quantity sensor that measures light quantity changes, a volume sensor that measures volume, a distance measuring sensor that measures distance, a flow rate sensor that measures the flow rate of a liquid or gas, a gyro sensor that measures angular velocity, an infrared sensor that measures infrared rays, a vibration sensor that measures vibration, etc. However, the types of the sensor unit 21 are not limited to these sensors.

[0038] Further, the sensor unit 21 can be built inside the wireless sensor 10 to enhance reliability. However, according to demands such as desiring to use it with good sensitivity by directly attaching only the sensor to the measurement point, or desiring to arrange and use only the sensor in a narrow space, it can also be externally connected to the wireless sensor 10.

[0039] <<Transmission and reception unit>> The transmission and reception unit 23 has a semiconductor for wireless communication, a transmission and reception antenna unit 24 for external communication, and a memory for storing settings. The transmission and reception unit 23 can use 920 MHz UHF band communication and 2.4 GHz band communication, but is not limited thereto, and communication using frequency bands other than the above may also be possible. Also, as a communication method of the transmission and reception unit 23, when it is desired to suppress power consumption, it is preferable to adopt a semi-passive communication method, and when there is a surplus of power, an active communication method can be adopted. Thereby, the communication distance can be extended and the freedom of communication can also be increased.

[0040] Further, as an example, the transmission and reception unit 23 is built in the second insulating layer 12 and is connected to the sensor unit 21 and the transmission and reception antenna unit 24 via the metal layer 14 and the through hole 16. Also, as will be described later, when the wireless sensor 10 has the control unit 22, the transmission and reception unit 23 is also connected to the control unit 22.

[0041] <<Transmission and reception antenna unit>> In addition, the transceiver antenna unit 24 is connected to the transceiver unit 23 via the metal layer 14 and the through-hole 16. Further, the transceiver antenna unit 24 is provided at least on the upper surface side (i.e., inside or on the surface of the first insulating layer 12). Of course, the transceiver antenna unit 24 may be provided so as to surround the upper and lower surfaces (front and back surfaces) of the wireless sensor 10.

[0042] <<Power Supply Unit>> The power supply unit 25 has a power generation element. The power generation element can include power generation elements such as a thermoelectric power generation harvester, a vibration power generation harvester, a MEMS harvester, a solar power generation harvester, and other harvester elements. With the above configuration, the semi-passive or active communication operation of the wireless sensor 10 becomes possible, and it is also possible to perform a communication operation without transmitting a large electromotive force from an external sensor data reading device 50 described later. Thereby, the risk of causing radio wave interference to an operating aircraft can be reduced, and it becomes possible to safely wirelessly transmit and receive sensor data.

[0043] Also, it is preferable that the power supply unit 25 further has a power storage element and a voltage control element (both not shown). Thereby, together with the above-described power generation element, power can be stably supplied to each of the elements 20, and the wireless sensor 10 can collect sensor data necessary and sufficient for the safe operation of the aircraft.

[0044] Also, as an example, the power supply unit 25 is built in the fourth insulating layer 12 and is connected to the sensor unit 21 and the transceiver unit 23 via the metal layer 14 and the through-hole 16. As will be described later, when the wireless sensor 10 has a control unit 22, the power supply unit 25 is also connected to the control unit 22.

[0045] Also, the power supply unit 25 may use an all-solid-state battery as the power storage element. Further, even in an environment where light, vibration, and temperature differences, which are difficult to utilize by the power generation element, are small, by adopting a configuration in which the built-in all-solid-state battery is charged during maintenance using non-contact power supply via a receiving coil, continuous sensing can be enabled.

[0046] <<Control Unit>> Furthermore, it is preferable that the elements 20 further include a control unit 22 that performs calculation, digitization, and overall operation management of sensor data.

[0047] The control unit 22 is, for example, built into the second insulating layer 12 and is connected to the sensor unit 21, the transceiver unit 23, and the power supply unit 25 via the metal layer 14 and the through hole 16.

[0048] The control unit 22 includes an MCU having a function of calculating and digitizing the sensor data acquired by the sensor unit 21 and a function of executing the operation control of the entire wireless sensor 10. In addition, one or more storage areas (not shown) are built into the control unit 22, and the sensor data may be stored. Note that the sensor data stored in the storage area is data that has been digitized by the control unit 22.

[0049] Note that the area where the sensor data is stored is not limited to the storage area in the control unit 22, and a configuration in which a storage area is provided in the transceiver unit 23 or a configuration in which another storage memory is provided may be adopted.

[0050] In addition, it is preferable that at least one of the control unit 22 and the transceiver unit 23 is configured to manage the sensor data with an individual identification ID. That is, the wireless sensor 10 preferably has a configuration including an identification ID for individual identification. Thereby, when a large number of wireless sensors 10, such as several hundred to several thousand, are used, the sensor data can be associated without confusion. The identification ID is held by the control unit 22 and / or the transceiver unit 23, but a configuration in which the identification ID is held using an external memory or the like other than that may be adopted. Also, in the case of a passive communication method or an active communication method having an identification ID in advance, the identification ID is used, and in the case of using other communication methods, individual identification can be enabled by adding a separate identification ID.

[0051] <<Others>> Note that, as shown in FIG. 3, in order to improve communication performance, the wireless sensor 10 can be attached to a metal part 40 such as a component or the fuselage of the aircraft 60. As the material of the metal part 40, materials such as copper, aluminum, titanium, stainless steel, and iron can be adopted, but it is not limited thereto. It can also be attached to a resin having conductivity such as carbon fiber. Of course, it may be configured to be attached other than the metal part 40 and the above-described resin.

[0052] In addition, as an example of the mode of attaching the wireless sensor 10 to the metal part 40, a method of fixing using a double-sided adhesive tape between the two can be mentioned, but it is not limited thereto, and it may be directly fixed with bolts and screws, or fixed using an adhesive or solder. It may be attached with a string or a tape.

[0053] Note that the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the scope of the present invention.

Explanation of Reference Numerals

[0054] 10 Wireless sensor 12 Multilayer printed wiring board (insulating layer) 14 Metal layer 16 Through hole 20 Elements 21 Sensor unit 22 Control unit 23 Transceiver unit 24 Transceiver antenna unit 25 Power supply unit 40 Metal part

Claims

1. A wireless sensor used in an aircraft, comprising elements related to sensing operations, a power supply unit related to power supply to the elements, and a transceiver antenna unit, wherein the elements and the power supply unit are three-dimensionally built in a multilayer printed wiring board and integrally sealed with a printed wiring board material, the power supply unit is an all-solid-state battery, and the wireless sensor is characterized in that continuous sensing is performed using the built-in all-solid-state battery even in an environment with little light, vibration, and temperature difference where it is difficult for power generation elements in the aircraft to be utilized.

2. The wireless sensor according to claim 1, wherein the all-solid-state battery is configured to be rechargeable during maintenance using contactless power supply.

3. The elements include a sensor unit that acquires predetermined sensor data, a control unit that performs calculation, digitization, and overall operation management of the sensor data, and a transceiver unit that externally communicates the data obtained by the sensor unit, and the wireless sensor according to claim 1 or claim 2, wherein the power supply unit further has a voltage control element.

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