Sensor module, communication unit, and system

Abstract

A sensor module (1) is attached to an opening (102) of a reservoir (100). The sensor module has: a TOF sensor (20) that measures a distance to a liquid surface (111) of a liquid (110) stored in the reservoir; an inclination detector (26) that detects the inclination of the TOF sensor; angle adjustment mechanisms (12, 52) that enable adjustment of the emission direction of TOF light emitted from the TOF sensor; and coupling parts (62, 63) that couple to the opening.

Description

Sensor module, communication unit, and system

[0001] The present invention relates to a sensor module for determining the amount of liquid stored in a reservoir, and further to a communication unit and system comprising such a sensor module.

[0002] Patent Document 1 describes a detection device that is attached to the opening of a reservoir and can detect the remaining amount of liquid in the reservoir. The detection device includes a distance sensor that measures the distance to the liquid level in the reservoir (i.e., the liquid level height).

[0003] A distance sensor used for such applications typically uses a TOF (Time of Flight) sensor that uses laser light or infrared light. The distance from the TOF sensor to the liquid surface can be measured by measuring the time it takes for pulsed light (TOF light) emitted from the TOF sensor to reflect off the liquid surface and return to the TOF sensor. The TOF sensor requires that the TOF light be incident perpendicularly on the liquid surface.

[0004] Patent Document 1 exemplifies an outdoor kerosene tank as a storage container to which a distance sensor can be attached. In particular, portable storage containers that are not stationary may be installed at an angle. In this case, the liquid level in the storage container is always horizontal regardless of the inclination of the storage container, whereas the distance sensor attached to the storage container emits TOF light in a direction corresponding to the inclination of the storage container. Therefore, if the storage container is tilted, the TOF light will not be incident perpendicularly on the liquid surface. Even if the storage container can be installed without tilting, if the detection device is attached at an angle to the storage container, the TOF light will similarly not be incident perpendicularly on the liquid surface. If the TOF light is not incident perpendicularly on the liquid surface, it is possible that measurements by the distance sensor will not be performed correctly.

[0005] Japanese Patent Application Laid-Open No. 2019-016006

[0006] Since it is generally not possible to observe the liquid level or the TOF light from outside the reservoir, it is difficult to adjust the tilt of the reservoir and / or the detection device so that the TOF light is incident perpendicularly on the liquid level in the reservoir (in other words, so that the TOF light is emitted in a vertical direction). Therefore, the detection device of Patent Document 1 has a problem in that it cannot correctly measure the distance from the detection device to the liquid level when the reservoir is tilted or when the detection device is attached at an angle to the reservoir.

[0007] An object of the present invention is to facilitate adjustment so that TOF light is emitted in the vertical direction.

[0008] The sensor module of the present invention is attached to an opening of a reservoir and includes a TOF sensor that measures the distance to the liquid surface of the liquid stored in the reservoir, a tilt detector that detects the tilt of the TOF sensor, an angle adjustment mechanism that enables adjustment of the emission direction of TOF light emitted from the TOF sensor, and a coupling part that couples to the opening.

[0009] A communication unit of the present invention includes the sensor module of the present invention described above and a receiver that receives information from the sensor module.

[0010] The system of the present invention comprises the communication unit of the present invention described above, and at least one storage device that stores the information as time-series data.

[0011] According to the present invention, it is easy to adjust the TOF light so that it is emitted vertically from the TOF sensor, so that the liquid level in the reservoir and even the amount of liquid in the reservoir can be accurately estimated even when the reservoir is tilted or the sensor module is attached at an angle relative to the reservoir.

[0012] Figure 1 is a cross-sectional view of a reservoir to which a sensor module according to an embodiment of the present invention is attached. Figure 2 is a cross-sectional view of a sensor module according to an embodiment of the present invention. Figure 3 is a cross-sectional view of a sensor module according to an embodiment of the present invention attached to a reservoir. Figure 4 is a block diagram showing an embodiment of the functional configuration of a sensor module, a communication unit, and a system of the present invention. Figure 5 is a cross-sectional view of a sensor module according to an embodiment of the present invention attached to a reservoir installed at an angle.

[0013] (1) A sensor module of the present invention is attached to an opening of a reservoir, and includes a TOF sensor that measures the distance to the liquid surface of the liquid stored in the reservoir, a tilt detector that detects the tilt of the TOF sensor, an angle adjustment mechanism that enables adjustment of the emission direction of TOF light emitted from the TOF sensor, and a coupling part that couples to the opening.

[0014] (2) The sensor module of the above item (1) may further include a processing unit that converts the measurement results of the TOF sensor into process data in a format that can be communicated, and a communication unit that transmits the process data to an external device. According to this aspect of item (2), it becomes easy to store the measurement results of the TOF sensor and to perform arithmetic processing for analysis.

[0015] (3) In the sensor module of (1) or (2), the tilt detector may include an acceleration sensor or a spirit level. If the tilt detector includes an acceleration sensor, it is easy to process information about the tilt of the TOF sensor detected by the acceleration sensor and display it in any format. Furthermore, if the tilt detector is a spirit level, it is easy to intuitively recognize the tilt of the TOF sensor.

[0016] (4) In the sensor module according to any one of (1) to (3), the angle adjustment mechanism may have a ball joint connection structure. This aspect is advantageous (i) in reducing the size and improving the reliability of the angle adjustment mechanism, and (ii) in facilitating adjustment of the emission direction of the TOF light to any direction.

[0017] (5) The sensor module according to any one of (1) to (4) above may further include an adapter for attaching the coupling portion to the opening of the reservoir. According to this aspect, the sensor module of the present invention can be attached to the openings of various reservoirs simply by changing the adapter.

[0018] (6) The sensor module according to any one of (1) to (5) above may further include a temperature sensor. According to this aspect, the temperature sensor can measure the ambient temperature and calibrate the TOF sensor. This is advantageous in improving the accuracy of the distance to the liquid surface measured by the TOF sensor.

[0019] (7) A communication unit of the present invention includes the sensor module according to any one of (1) to (6) above and a receiver for receiving information from the sensor module. Such a communication unit facilitates storing and analyzing measurement results from the TOF sensor.

[0020] (8) A system of the present invention includes the communication unit of (7) above and at least one storage device that stores the information as time-series data. Such a system facilitates the storage of measurement results obtained by the TOF sensor. The data stored in the storage device can be analyzed or displayed as needed.

[0021] (9) The sensor module according to any one of (1) to (6) may estimate the amount of liquid stored in the reservoir from the distance to the liquid level measured by the TOF sensor. According to this aspect, a self-contained sensor module capable of estimating the amount of liquid in the reservoir can be realized.

[0022] (10) The system according to (8) above may estimate the amount of liquid stored in the reservoir from the distance to the liquid level measured by the TOF sensor. According to this aspect, the calculation for estimating the amount of liquid can be performed outside the sensor module. This is advantageous for miniaturizing the sensor module.

[0023] The present invention will be described in detail below, illustrating preferred embodiments. However, it goes without saying that the present invention is not limited to the following embodiments. The drawings referred to in the following description show simplified main components constituting the embodiments of the present invention for the convenience of explanation. Therefore, the present invention may include any components not shown in the following drawings. Furthermore, within the scope of the present invention, the components shown in the following drawings may be modified or omitted. The components shown in the drawings are not shown to exact scale and may be exaggerated.

[0024] FIG. 1 is a cross-sectional view showing a reservoir 100 to which a sensor module 1 according to one embodiment of the present invention is attached. The reservoir 100 is a container (or tank) for storing a liquid 110, and may be, for example, a drum. The liquid 110 may be, but is not limited to, a fuel oil such as kerosene or diesel, or any other liquid. In the present invention, the term "liquid" may be viscous and may also include a gel-like substance. The shape of the reservoir 100 is, but is not limited to, a hollow cylinder or a hollow rectangular parallelepiped. The top and bottom ends of the reservoir 100 are closed by a top plate 101 and a bottom plate 107, respectively. The top plate 101 has at least one opening 102 (two openings 102 are shown in FIG. 1 ). The opening 102 is opened when the liquid 110 is to be introduced into or removed from the reservoir 100, and is otherwise closed by a cap 105. The sensor module 1 is detachably attached to the opening 102 instead of the cap 105. The sensor module 1 includes a TOF sensor (details of which will be described later). The TOF sensor emits TOF light 21 toward the liquid 110. The TOF light 21 is reflected by a liquid surface 111 of the liquid 110 and enters the TOF sensor. The TOF sensor can measure the distance from the TOF sensor to the liquid surface 111.

[0025] 2 is a cross-sectional view of the sensor module 1. The sensor module 1 includes a housing portion 50 and a swing portion 10 held by the housing portion 50 so as to be swingable.

[0026] The housing unit 50 includes, but is not limited to, an upper housing 55 and a lower housing 60. The upper housing 55 has a generally circular ring shape with an opening 57 in the center. The lower housing 60 has a generally circular dish shape with an opening in the center. A hollow cylindrical connecting tube 62 extends downward from the edge of the opening of the lower housing 60. A male thread 63 is formed on the outer circumferential surface of the connecting tube 62. The upper housing 55 and the lower housing 60 are joined in the vertical direction, and these are integrated with screws 59 to form the housing unit 50. The housing unit 50 can be made of, but is not limited to, a flame-retardant synthetic resin such as polycarbonate or flame-retardant grade polystyrene.

[0027] The housing portion 50 has a concave spherical surface 52 formed by the inner circumferential surfaces of the upper housing 55 and the lower housing 60. The spherical surface 52 corresponds to a complete sphere cut by two planes spaced apart in the vertical direction (the planes are perpendicular to the axis of the housing portion 50, i.e., the axis of the connecting tube 62), and the portion between the two planes is extracted. The center of the spherical surface 52 is located between the two planes. A continuous annular groove 53 is formed in the spherical surface 52, extending circumferentially along the joint between the upper housing 55 and the lower housing 60. An O-ring (first O-ring) 54 is fitted into the annular groove 53 and held in the housing portion 50. The O-ring 54 provides a seal between the upper housing 55 and the lower housing 60. An O-ring (second O-ring) 64 is fitted onto the connecting tube 62.

[0028] The swinging unit 10 includes a case 11. The case 11 is formed by joining an upper case 13 and a lower case 15 together in the vertical direction, although this is not a limitation. The case 11 can be made of a flame-retardant synthetic resin, such as polycarbonate or flame-retardant polystyrene. The case 11 includes a spherical surface 12 on its outer periphery. The spherical surface 12 corresponds to a portion obtained by cutting a perfect sphere with two planes spaced apart in the vertical direction (the planes are perpendicular to the axis of the case 11) and extracting the portion between the two planes. The center of the spherical surface 12 is located between the two planes. The swinging unit 10 is held in the housing 50 so that the spherical surface 12 is inscribed in a spherical surface 52. The radius of the spherical surface 52 is larger than the radius of the spherical surface 12 by a small amount of play. Therefore, the swinging part 10 can tilt (i.e. swing) in any direction with respect to the housing part 50, with the spherical surface 12 held substantially concentric with the spherical surface 52. The swingable connection structure of the swinging part 10 with respect to the housing part 50 constitutes a ball joint connection structure in which the two spherical surfaces 12, 52 are combined. An O-ring 54 seals between the spherical surfaces 12 and 52. An opening 16, which is a hole that penetrates the lower case 15, is formed in the center of the lower case 15.

[0029] The oscillating unit 10 includes a TOF sensor 20, an acceleration sensor 26, a circuit board 30, and a power supply 41 inside a case 11. When the oscillating unit 10 oscillates relative to the housing unit 50, the case 11 and these components housed in the case 11 oscillate integrally relative to the housing unit 50.

[0030] The TOF sensor 20 is mounted on the lower surface of the circuit board 30 so as to be exposed to the outside world through the opening 16 .

[0031] The acceleration sensor 26 is mounted on the upper surface of the circuit board 30. The acceleration sensor 26 is a three-axis acceleration sensor that can detect changes in the attitude (particularly the tilt) of the oscillating part 10 including the TOF sensor 20.

[0032] The circuit board 30 is a substantially circular or rectangular flat plate, although not limited thereto, and covers the opening 16 of the case 11. In addition to the above-described TOF sensor 20 and acceleration sensor 26, any electronic components such as a microcomputer, a temperature sensor, an antenna, and a start-up photosensor may be mounted on the circuit board 30.

[0033] The power source 41 may be a primary battery (e.g., a coin-type lithium battery) or a secondary battery (e.g., a lithium-ion battery). When the storage device 100 is installed in an environment subject to high and / or low temperatures, it is preferable to use a battery having high heat resistance and / or cold resistance, such as a heat-resistant CR battery or an all-solid-state battery, as the power source 41.

[0034] The swinging portion 10 has, but is not limited to, a resin-filled explosion-proof structure in which the inside of the case 11 is filled with insulating resin 18 .

[0035] As shown in Fig. 3, the sensor module 1 is attached to the reservoir 100. The male thread 63 of the coupling tube 62 is screwed into the female thread 103 formed in the opening 102 of the reservoir 100. An O-ring (second O-ring) 64 fitted onto the coupling tube 62 is compressed in the vertical direction by the lower housing 60 (see Fig. 2) and the opening 102, thereby sealing the gap between the lower housing 60 and the opening 102.

[0036] The TOF sensor 20 includes a light-projecting unit and a light-receiving unit (neither of which are shown). The light-projecting unit of the TOF sensor 20 emits pulsed TOF light 21 downward, spreading at a certain angle (FoV: Field of View). The optical axis of the TOF light 21 is parallel to the axis of the swinging unit 10 (i.e., the axis of the case 11 (see FIG. 2)). The TOF light 21 passes through the opening 16 (see FIG. 2) of the case 11 and the connecting tube 62 of the housing unit 50 into the reservoir 100. The TOF light 21 is reflected by the liquid surface 111 of the liquid 110 stored in the reservoir 100 and passes through the connecting tube 62 and the opening 16 to enter the light-receiving unit of the TOF sensor 20. By measuring the time of flight (time of flight) from when the TOF light 21 is emitted from the light projecting unit until it returns to the light receiving unit, the distance from the TOF sensor 20 to the liquid surface 111 of the liquid 110 can be measured.

[0037] FIG. 4 is a block diagram showing the functional configuration of the sensor module 1 and the communication unit 7 and system 8 including the sensor module 1.

[0038] The sensor module 1 includes a swinging portion 10 and a housing portion 50 .

[0039] The oscillating unit 10 is coupled to the housing unit 50 via an angle adjustment mechanism 19. The angle adjustment mechanism 19 makes it possible to adjust the tilt of the oscillating unit 10 relative to the housing unit 50 to any desired direction. By adjusting the tilt of the oscillating unit 10, it is possible to adjust the emission direction of TOF light 21 emitted from the TOF sensor 20 provided on the oscillating unit 10. The sensor module 1 of this embodiment includes, as the angle adjustment mechanism 19, a ball joint coupling structure (see FIG. 2 ) in which the spherical surface 12 of the oscillating unit 10 and the spherical surface 52 of the housing unit 50 are combined. However, in the present invention, the configuration of the angle adjustment mechanism 19 is not limited to this. For example, the angle adjustment mechanism 19 may be composed of a composite coupling mechanism with two rotational degrees of freedom, including a first coupling mechanism that couples the oscillating portion 10 to the housing portion 50 with a rotational degree of freedom around the axis of the housing portion 50, and a second coupling mechanism that couples the oscillating portion 10 to the housing portion 50 with a rotational degree of freedom around an axis perpendicular to the axis of the housing portion 50.

[0040] The housing 50 includes a coupling portion 61 for coupling the sensor module 1 to the opening 102 of the reservoir 100. In this embodiment, the coupling portion 61 includes a coupling tube 62 and a male screw 63 (see FIG. 3 ). However, in the present invention, the configuration of the coupling portion 61 is not limited thereto and may be changed as appropriate depending on the configuration of the opening 102. Preferably, the coupling portion 61 is configured so that it can be directly attached to the opening 102 of the reservoir 100 (see FIG. 3 ). However, if the coupling portion 61 cannot be directly attached to the opening 102, the coupling portion 61 may be attached to the opening 102 via an adapter 65. The configuration of the adapter 65 is not limited, but preferably has a hollow cylindrical shape with both ends open so that the TOF light 21 can pass through, and one end of the cylindrical shape is configured to be detachable from the coupling portion 61 and the other end of the cylindrical shape is configured to be detachable from the opening 102.

[0041] The swinging unit 10 incorporates a TOF sensor 20, a tilt detector 25, a processing unit 33, a communication unit 35, a temperature sensor 37, and a power supply unit 40.

[0042] The tilt detector 25 detects the tilt of the oscillating unit 10 including the TOF sensor 20. In this embodiment, the tilt detector 25 is an acceleration sensor 26 (see FIG. 2 ). The sensor module 1 may also include a display unit (not shown) that displays the tilt of the oscillating unit 10 detected by the acceleration sensor 26. The display unit may be installed, for example, on the top surface of the oscillating unit 10 (e.g., the top surface of the upper case 13 (see FIG. 2 )). Alternatively, information regarding the tilt of the oscillating unit 10 detected by the acceleration sensor 26 may be transmitted to the receiver 70 or the storage device 80, and the tilt of the oscillating unit 10 may be displayed on any display device (not shown) connected to the receiver 70 or the storage device 80. Note that, in the present invention, the tilt detector 25 is not limited to the acceleration sensor 26. For example, the tilt detector 25 may be a spirit level in which a liquid such as alcohol is sealed in a transparent container together with air bubbles, allowing the tilt to be detected based on the position of the air bubbles. When the tilt detector 25 is configured as a spirit level, the spirit level is preferably installed on the top surface of the upper case 13 (see FIG. 2), for example, so that it can be seen by an operator.

[0043] The processing unit 33 converts the measurement results (or output signals) from the TOF sensor 20 into processed data in a format that can be communicated. The processing unit 33 may further have the function of processing various signals within the sensor module 1 and controlling the operation of the sensor module 1. The processing unit 33 may be configured, for example, by a known microcomputer, without being limited thereto. The processing unit 33 can be mounted on the circuit board 30 (see FIG. 2).

[0044] The communication unit 35 transmits the processed data output from the processing unit 33 to the outside (receiver 70). There are no limitations on the method of transmitting the processed data performed by the communication unit 35, and either wireless or wired transmission may be used. Preferably, the communication unit 35 performs wireless transmission using Bluetooth (Bluetooth Classic), Bluetooth Low Energy (1M PHY, Coded PHY (Lon Range)), ZigBee, LTE-M, Sigfox, or the like. The communication unit 35 may have an antenna for performing these wireless transmissions. The communication unit 35 can be mounted on the circuit board 30 (see FIG. 2 ).

[0045] The temperature sensor 37 detects the ambient temperature of the sensor module 1. The temperature data detected by the temperature sensor 37 is used for calibrating the TOF sensor 20. The calibration may be performed by, but is not limited to, the processing unit 33. The temperature sensor 37 can be mounted on the circuit board 30 (see FIG. 2).

[0046] The power supply unit 40 supplies power to the TOF sensor 20, the tilt detector 25, the processing unit 33, the communication unit 35, and the temperature sensor 37. In this embodiment, the power supply unit 40 includes a power source 41 (see FIG. 2).

[0047] The communication unit 7 includes the sensor module 1 and a receiver 70. The receiver 70 includes a communication section 71 that receives information (processing data) transmitted from the communication section 35 of the sensor module 1. The communication section 71 may have an antenna for wireless transmission between the communication section 35. The receiver 70 may be configured as, but is not limited to, a known gateway.

[0048] The system 8 includes a communication unit 7 and a storage device 80. The storage device 80 stores information from the sensor module 1 as time-series data. The storage device 80 may be configured using known memory such as, but not limited to, Flash, SRAM, DRAM, FeRAM (ferroelectric memory), or EEPROM. The storage device 80 may be connected to or built into a personal computer. The personal computer may include a calculation circuit that calculates the amount of liquid 110 in the reservoir 100 using information on the distance to the liquid level 111 measured by the TOF sensor 20 and shape data of the reservoir 100. Information regarding the amount of liquid 110 may be stored in the storage device 80. The personal computer may generate a control signal for controlling the sensor module 1 and transmit it to the sensor module 1 via the receiver 70. The storage device 80 may be connected to a display device (e.g., a monitor) that displays the information stored in the storage device 80.

[0049] 4 is an example, and the present invention is not limited thereto. For example, the processing unit 33 of the sensor module 1 may calculate the amount of liquid 110 in the reservoir 100 using information on the distance to the liquid level 111 measured by the TOF sensor 20, shape data of the reservoir 100, and the like. In this case, the sensor module 1 may be provided with a display device (e.g., a display) that displays the calculation results. The calculation results may be stored in the sensor module 1, or may be stored in the storage device 80 via the communication unit 35.

[0050] An example of how to use the sensor module 1 of this embodiment will be described.

[0051] As shown in Fig. 3, the sensor module 1 is attached to the opening 102 of the reservoir 100 in which the liquid 110 is stored. TOF light 21 is emitted from the TOF sensor 20. The TOF light 21 is reflected by the liquid surface 111 of the liquid 110 and enters the TOF sensor 20. The TOF sensor 20 can be used to measure the distance from the TOF sensor 20 to the liquid surface 111 of the liquid 110. Based on the distance from the TOF sensor 20 to the liquid surface 111, the height of the liquid surface 111 in the reservoir 100, and further the amount of liquid in the reservoir 100, can be estimated.

[0052] 3 shows a case where the reservoir 100 is installed without tilt. The TOF sensor 20 emits TOF light 21 in the vertical direction. Since the liquid surface 111 is horizontal, the TOF light 21 is incident perpendicularly on the liquid surface 111. The TOF light 21 is reflected vertically by the liquid surface 111 and enters the TOF sensor 20.

[0053] For example, if the reservoir 100 is portable, it may be installed at an angle. FIG. 5 illustrates a case in which the reservoir 100 is installed at an angle. The housing 50 of the sensor module 1 is tilted in accordance with the tilt of the reservoir 100. Meanwhile, the liquid level 111 in the reservoir 100 is always horizontal regardless of the tilt of the reservoir 100. In this case, the tilt of the oscillating unit 10 is detected by the tilt detector 25 (acceleration sensor 26 (see FIG. 2)), and the tilt of the oscillating unit 10 is adjusted so that the axis of the oscillating unit 10 (i.e., the emission direction of the TOF light 21) is vertical. The tilt of the oscillating unit 10 can be adjusted, for example, by directly touching the oscillating unit 10 with a finger through the opening 57 on the top surface of the housing 50. After confirming that the axis of the oscillating unit 10 is aligned vertically, the TOF light 21 is emitted from the TOF sensor 20.

[0054] The sensor module 1 includes a tilt detector 25 (acceleration sensor 26) that detects the tilt of the oscillating unit 10 (i.e., the TOF sensor 20) and an angle adjustment mechanism 19 (spherical surfaces 12, 52) that enables adjustment of the tilt of the oscillating unit 10 (i.e., the emission direction of the TOF light 21). Therefore, even if the reservoir 100 is installed at an angle as shown in FIG. 5 , the TOF light 21 can be emitted vertically from the TOF sensor 20. Because the liquid surface 111 of the liquid 110 in the reservoir 100 is always parallel to the horizontal direction regardless of the tilt of the reservoir 100, the TOF light 21 is incident perpendicularly on the liquid surface 111. Therefore, the TOF light 21 reflected by the liquid surface 111 reliably returns to the TOF sensor 20. Therefore, by using the sensor module 1, the height of the liquid surface 111 in the reservoir 100 and the amount of the liquid 110 in the reservoir 100 can be estimated in the same manner as in FIG. 3 . For example, even if the reservoir 100 is mounted on a vehicle or the like and is tilted, it is possible to estimate the amount of liquid 110 in the reservoir 100. There is no need to perform complicated work such as correcting the tilt of the reservoir 100 in order to estimate the amount of liquid 110. Therefore, the amount of liquid 110 can be estimated efficiently.

[0055] Even if the reservoir 100 is installed without tilting, if the sensor module 1 (particularly its housing 50) is attached at an angle relative to the reservoir 100, for example, because the top plate 101 or the opening 102 is deformed, the TOF light 21 from the TOF sensor 20 will not be perpendicularly incident on the liquid surface 111. In this case, as in the case of Figure 5, the tilt of the oscillating unit 10 (i.e., the emission direction of the TOF light 21) can be adjusted to align the axis of the oscillating unit 10 (i.e., the emission direction of the TOF light 21) with the vertical direction. Therefore, the height of the liquid surface 111 in the reservoir 100, and further the amount of liquid 110 in the reservoir 100, can be estimated.

[0056] The sensor module of the present invention may have a tilt detector (second tilt detector) separate from the tilt detector (first tilt detector) 25. The second tilt detector can be used, for example, to detect the tilt (attitude) of the reservoir 100. By combining the height of the liquid level 111 obtained using the TOF sensor 20 with the tilt of the reservoir 100, the amount of liquid 110 in the reservoir 100 can be more accurately estimated. The second tilt detector may be, but is not limited to, an acceleration sensor or a spirit level. The second tilt detector may be, but is not limited to, installed in the housing 50 or directly in the reservoir 100.

[0057] The present invention can be widely used in any field where it is necessary to estimate the amount of liquid stored in a reservoir.

[0058] REFERENCE SIGNS LIST 1 sensor module 7 communication unit 8 system 10 swinging part 12 spherical surface (ball joint connection structure, angle adjustment mechanism) 19 angle adjustment mechanism 20 TOF sensor 21 TOF light 25 tilt detector 26 acceleration sensor (tilt detector) 33 processing part 35 communication part of sensor module 37 temperature sensor 40 power supply part 41 power supply 50 housing part 52 spherical surface (ball joint connection structure, angle adjustment mechanism) 61 connection part 62 connection tube (connection part) 63 male thread (connection part) 65 adapter 70 receiver 71 communication part of receiver 80 storage device 100 reservoir 102 reservoir opening 110 liquid in reservoir 111 liquid level

Claims

1. A sensor module to be attached to the opening of a reservoir, the sensor module having: a TOF sensor that measures the distance to the liquid surface of the liquid stored in the reservoir; a tilt detector that detects the tilt of the TOF sensor; an angle adjustment mechanism that enables adjustment of the emission direction of the TOF light emitted from the TOF sensor; and a coupling part that couples to the opening.

2. The sensor module according to claim 1, further comprising: a processing unit that converts the measurement results obtained by the TOF sensor into processed data in a format that can be communicated; and a communication unit that transmits the processed data to the outside.

3. The sensor module of claim 1, wherein the tilt detector comprises an acceleration sensor or a spirit level.

4. The sensor module according to claim 1, wherein the angle adjustment mechanism comprises a ball joint coupling structure.

5. The sensor module of claim 1, further comprising an adapter for attaching said coupling portion to said opening of said reservoir.

6. The sensor module of claim 1, further comprising a temperature sensor.

7. A communication unit comprising: a sensor module according to claim 1; and a receiver for receiving information from the sensor module.

8. A system comprising: a communication unit according to claim 7; and at least one storage device that stores the information as time-series data.

9. The sensor module according to claim 1, wherein the amount of liquid stored in the reservoir is estimated from the distance to the liquid level measured by the TOF sensor.

10. The system according to claim 8, wherein the amount of liquid stored in the reservoir is estimated from the distance to the liquid level measured by the TOF sensor.

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