Seat Wetness Detection Device

Abstract

To provide a seat wet detection device capable of simply and accurately detecting wet on a seat part of a seat in a wider range.SOLUTION: A seat wet detection device includes: a sensor 11 that is provided at a height downwardly facing a seat part 3 of a seat 1 and transmits an electromagnetic wave toward a seat surface of the seat part 3 opposing to a front side and receives a reflection wave of the electromagnetic wave on the front side; and a reflection part 31 that is provided so as to overlap with the seat surface in the seat part 3 in plan view and serves as a seat part frame 30 in the seat part 3. Wet of the seat part 3 can be determined on the basis of a degree of attenuation of signal intensity due to a water content of the reflection wave from the reflection part 31.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a seat wetness detection device for detecting wetness of a seat portion in a seat.

Background Art

[0002] The applicant of the present application has already proposed a seat wetness detection device that can be miniaturized, has excellent wearability on a seat, and can accurately detect wetness of the seat by simple control. This seat wetness detection device includes a millimeter-wave sensor that transmits and receives millimeter waves toward the seat, and a reflection portion that is disposed inside the seat and reflects the millimeter waves from the millimeter-wave sensor. Based on the degree of attenuation of the signal intensity of the reflected wave from the reflection portion due to moisture, it was possible to determine the wetness of the seat.

[0003] As a specific embodiment of such a seat wetness detection device, the millimeter-wave sensor is provided in a sleeve portion on the side of the seat portion in the seat, and is arranged to irradiate millimeter waves from the side toward the seat surface of the seat portion located directly below it. Further, below the seat surface of the seat portion, which is the irradiation range of the millimeter waves, a plurality of substantially rectangular and small metal plates are arranged at different positions as the reflection portion.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Regarding the aforementioned seat wetness detection device, improvements were desired to address the following new problems with its specific embodiment. Specifically, the millimeter-wave sensor is installed on the armrest on the side of the seat surface, and emits millimeter waves from a close, lateral position relative to the seat surface. As a result, the irradiation range of the millimeter waves on the seat surface is relatively narrow, and if the metal plate, which acts as the reflector, is even slightly misaligned from the front of the millimeter-wave sensor, the reflection intensity decreases drastically, further narrowing the detection area.

[0006] Furthermore, depending on the positional relationship between the millimeter-wave sensor in the sleeve and the seat, the areas slightly forward and to the sides of the seat surface tend to be blind spots in the millimeter-wave illumination range, making it difficult to detect wetting in those areas. In addition, since the metal plates that act as reflectors are placed separately from the seat's original frame, there was a problem of increased costs due to the increased number of parts and assembly man-hours. Moreover, if the angle of each metal plate deviates even slightly from the angle directly facing the millimeter-wave sensor, the reflection intensity of the millimeter waves becomes extremely weak, as mentioned above, so it was troublesome to adjust the reflection angle of the metal plates.

[0007] This invention was made in view of the problems of the prior art described above, and aims to provide a seat wetness detection device that can easily and accurately detect seat wetness over a wider area without increasing costs, by ensuring that the irradiation range of electromagnetic waves, including millimeter waves, covers the entire seat surface, eliminating blind spots where water leakage detection on the seat surface is impossible, and eliminating the troublesome work of adjusting the reflection angle of the reflector. [Means for solving the problem]

[0008] To achieve the aforementioned objectives, one aspect of the present invention is: A seat wetness detection device for detecting wetness on a seat, A sensor is installed at a height that looks downward from the seat portion of the seat, and transmits electromagnetic waves from the front towards the seat surface of the opposite seat, and receives the reflected waves that are returned from the front. It comprises a reflective section that is positioned within the seat so as to overlap the seat surface in a plan view, and which also serves as the seat frame within the seat, The reflective portion is capable of receiving electromagnetic waves transmitted from the sensor over its entire upper surface and reflecting them back toward the sensor. The system is characterized by its ability to determine whether the seat is wet based on the degree of attenuation of the signal intensity due to moisture in the reflected wave received by the sensor. [Effects of the Invention]

[0009] The seat wetness detection device according to the present invention makes it possible to easily and accurately detect wetness on the seat surface over a wider area without increasing costs. [Brief explanation of the drawing]

[0010] [Figure 1] This is a perspective view showing a seat to which the seat wetness detection device according to this embodiment is applied. [Figure 2] A perspective view showing the internal structure of a seat to which the seat wetness detection device according to this embodiment is applied. [Figure 3] This is a front view showing the internal structure of a seat to which the seat wetness detection device according to this embodiment is applied. [Figure 4] This is a plan view showing the internal structure of a seat to which the seat wetness detection device according to this embodiment is applied. [Figure 5] This is a side view showing the internal structure of a seat to which the seat wetness detection device according to this embodiment is applied. [Figure 6] This is a perspective view showing the seat frame, which also serves as the reflective part of the seat wetness detection device according to this embodiment. [Figure 7] This is a plan view showing the seat frame, which also serves as the reflective part of the seat wetness detection device according to this embodiment. [Figure 8] This is a side view showing the seat frame, which also serves as the reflective part of the seat wetness detection device according to this embodiment. [Figure 9] This is a bottom view showing the seat frame, which also serves as the reflective part of the seat wetness detection device according to this embodiment. [Figure 10]It is a perspective view showing a corner reflector forming a reflection part of a seat wetness detection device according to this embodiment. [Figure 11] It is a perspective view showing a unit of a corner reflector forming a reflection part of a seat wetness detection device according to this embodiment. [Figure 12] It is a plan view showing a unit of a corner reflector forming a reflection part of a seat wetness detection device according to this embodiment. [Figure 13] It is a side view showing a support bracket of a reflection part of a seat wetness detection device according to this embodiment. [Figure 14] It is a plan view showing a support bracket of a reflection part of a seat wetness detection device according to this embodiment. [Figure 15] It is a front view showing a support bracket of a reflection part of a seat wetness detection device according to this embodiment. [Figure 16] It is a block diagram schematically showing a seat wetness detection device according to this embodiment. [Figure 17] It is an explanatory view showing how millimeter waves from a millimeter wave sensor of a seat wetness detection device according to this embodiment change in a dry state and a wet state of a seat. [Figure 18] It is an explanatory view showing an example of a method for detecting wetness of a seat in a seat wetness detection device according to this embodiment. [Figure 19] It is a flowchart showing an example of processing after detecting wetness of a seat in a seat wetness detection device according to this embodiment. [Figure 20] It is a perspective view showing an internal structure of a seat to which a seat wetness detection device according to Modification 1 of this embodiment is applied. [Figure 21] It is a plan view showing an internal structure of a seat to which a seat wetness detection device according to Modification 1 of this embodiment is applied. [Figure 22] It is an explanatory view showing an example of graphically displaying and showing the signal intensity of a reflected wave in a seat wetness detection device according to Modification 1 of this embodiment. [Figure 23] It is a perspective view showing an internal structure of a seat to which a seat wetness detection device according to Modification 2 of this embodiment is applied. [Figure 24]This is a plan view showing the internal structure of a seat to which the seat wetness detection device according to Modification 2 of this embodiment is applied. [Figure 25] This is an explanatory diagram showing an example of a graph displaying the signal intensity of the reflected wave in a seat wetness detection device according to a modified example 2 of this embodiment. [Modes for carrying out the invention]

[0011] Hereinafter, a representative embodiment of the present invention will be described based on the drawings. Figures 1 to 19 show one embodiment of the present invention. The seat wetness detection device 10 according to this embodiment uses electromagnetic waves, particularly millimeter-wave radar, to detect wetness of the seat 1, especially the seat portion 3. Hereinafter, the seat 1 will be described using a seat installed in the passenger compartment of a railway vehicle as an example. Note that the components, shapes, numerical values, etc. shown in the embodiments described below are all examples of the present invention and are not intended to limit the present invention.

[0012] <Overview of Seat 1> As shown in Figure 1, the seat 1 consists of a seat portion 3 attached to a base 2, with a backrest 4 supported on the rear end side of the seat portion 3. The base 2 is a metal base that supports the entire seat 1 on the floor, and includes, for example, a pair of side plates 20, 20 fixed opposite each other on the left and right sides. The front ends of each side plate 20 are connected via a front shaft 21, the rear ends of each side plate 20 are connected via a rear shaft 22, and the approximate centers of each side plate 20 are connected via an intermediate shaft 23.

[0013] As shown in Figures 1 to 5, the seat portion 3 is formed by attaching a cushion 3a to a seat frame 30, which is a seat frame fixed on the leg base 2, and covering the surface of the cushion 3a, including the seat surface, with a cover. The seat frame 30 is made of metal and is generally formed in the shape of a roughly rectangular panel, but as shown in Figures 6 to 9, it is configured to also serve as a reflector portion 31, which will be described later. A mounting portion 30b that supports the backrest frame 40, which will be described next, is provided at the rear end of the seat frame 30. The seat frame 30 is assembled to the upper side of the front shaft 21 and the rear shaft 22 via a mounting bracket 30c. Although not shown, armrests may be provided on both sides of the seat portion 3, similar to the aforementioned Patent Document 1.

[0014] The backrest 4 is formed by attaching a cushion 4a to a backrest frame 40, which is a back frame supported at the rear end of the seat frame 30, and covering the surface of the cushion 4a with a cover. The backrest frame 40 is formed in the shape of a vertically elongated, roughly rectangular panel by combining multiple metal materials. Here, the backrest frame 40 is rotatably supported at the rear end of the seat frame 30, and the tilt angle of the backrest 4 is configured to be adjustable via a damper 5 of the reclining mechanism.

[0015] As shown in Figure 1, the upper side of the backrest 4 is provided with front side sections 4b that protrude forward from both the left and right sides, and a separate headrest 4c is attached between them. A reading light 6 is provided on one of the front side sections 4b, and a millimeter-wave sensor 11, which will be described later, is located inside next to it. As shown in detail in Figure 2, a support bracket 50 for attaching the millimeter-wave sensor 11 is fixed to one end of the upper end 41 of the backrest frame 40. The support bracket 50, along with the millimeter-wave sensor 11, will also be described in detail later.

[0016] In such a seat 1, the seat frame 30 (reflective part 31) within the seat 3, which is the target of wetness detection, is made of metal and does not transmit electromagnetic waves. However, the cushion 3a is generally made of synthetic resin such as foamed urethane and therefore transmits electromagnetic waves, and the cover is also generally made of cloth and therefore transmits electromagnetic waves. The millimeter waves transmitted from the millimeter wave sensor 11, which will be described later, are also reflected by the leg rest 2 and other parts of the seat 1, but the reflection angle of such reflected light is not such that it returns to the millimeter wave sensor 11 except for slight diffuse reflection.

[0017] <Overview of Seat Wetness Detection Device 10> Figure 16 is a schematic block diagram showing the seat wetness detection device 10 according to this embodiment. As shown in Figure 16, the seat wetness detection device 10 comprises a millimeter-wave sensor 11, a reflector 31, and a controller 60. The millimeter-wave sensor 11 and the controller 60 are connected to each other via wireless or wired means so that they can send and receive signals from one another. A display unit 65 and an operation unit 66 are also connected to the controller 60. Here, the millimeter-wave sensor 11 corresponds to the "sensor" of the present invention.

[0018] The millimeter-wave sensor 11, as will be described in more detail later, comprises a transmitting unit 12 that transmits millimeter waves, a type of electromagnetic wave, and a receiving unit 13 that receives millimeter waves. Figure 16 also illustrates the state in which millimeter waves transmitted from the millimeter-wave sensor 11 toward the base unit 3 (hereinafter referred to as "transmitted waves") are returned as millimeter waves reflected by the reflecting unit 31, which will be described later (hereinafter referred to as "reflected waves"). Here, since millimeter waves have a constant frequency as a so-called chirp signal, they are represented as a sine wave whose magnitude (amplitude) is expressed as a function of time.

[0019] <About millimeter waves> The millimeter waves used in this embodiment refer to electromagnetic waves with a frequency band of 30 to 300 GHz, and are called "millimeter waves" (EHF) because their wavelength is 1 to 10 mm. Millimeter waves generally have the characteristics of being highly linear, being able to be treated like lasers, being able to secure a wide bandwidth, and being able to penetrate various materials such as synthetic resins and cloths. Furthermore, as a result of the inventors' diligent research, it has been found that the signal strength of millimeter waves is easily attenuated by moisture.

[0020] Experiments conducted by the inventors revealed that when millimeter waves (indicated as F in Figure 1) were irradiated onto the seat portion 3 of the seat 1 using the millimeter-wave sensor 11 described below, the millimeter waves passed directly through the cushion 3a of the seat portion 3 and were reflected by the internal metal seat portion frame 30 and leg rest 2. When the seat portion 3 was in a normal dry state, the reflected waves from the seat portion frame 30, etc., did not differ significantly from the signal strength at the time of transmission. However, when the seat portion 3 was wet, a clear attenuation of the signal strength of the reflected waves was observed. Therefore, it was found that millimeter waves are easily absorbed by moisture.

[0021] <Millimeter-wave sensor 11> The millimeter-wave sensor 11 is generally a module capable of measuring distance, direction, and velocity to a distant target, but in this embodiment, it is used specifically for measuring the signal strength of millimeter waves reflected from the reflector 31, which will be described later. Therefore, in this embodiment, the processing for measuring the distance, direction, and velocity to the reflector 31, which is fixed in a fixed position, is omitted. The millimeter-wave sensor 11 comprises a transmitting unit 12 that transmits the generated millimeter waves toward the base 3, and a receiving unit 13 that receives the millimeter-wave sensor reflected from the reflector 31.

[0022] More specifically, the millimeter-wave sensor 11 typically consists of radio frequency components for transmitting (TX) and receiving (RX), analog components such as a synthesizer and clock, an A / D converter, a digital signal processor (DSP), and digital components such as a microcontroller (MCU). The millimeter-wave sensor 11 transmits millimeter waves generated by the synthesizer from the TX antenna, and receives the reflected waves that are reflected when these transmitted waves hit a target (reflector 31) with the RX antenna. Therefore, in this embodiment, the TX antenna corresponds to the "transmitting unit 12," and the RX antenna corresponds to the "receiving unit 13."

[0023] The millimeter-wave sensor 11 also has a function to generate an IF signal (an intermediate frequency used for calculations) by mixing the transmitted wave and the reflected wave in a mixer, and to acquire information such as the position of the target (reflector 31) by performing various signal processing based on the data obtained from this IF signal. As a result, the millimeter-wave sensor 11 can distinguish the reflected waves from the auxiliary reflectors 31A and 31B, which will be described later, in addition to the reflector 31, and generate electrical signals according to the signal strength of each. The electrical signals generated here are output to the controller 60, which will be described later.

[0024] Such a millimeter-wave sensor 11 has the following features: it is resistant to environmental changes due to the linearity of millimeter waves, has excellent high-range resolution due to the wide bandwidth of millimeter waves, and enables high-precision detection because millimeter waves have a short wavelength, as well as allowing for miniaturization of the circuit and antenna. One of the features of the millimeter-wave sensor 11 is that it can be miniaturized, so the entire structure can be made up of a substrate that is only a few centimeters square. Therefore, as shown in Figure 1, the millimeter-wave sensor 11 of this embodiment can be installed even in the limited space within the front side portion 4b above the backrest 4.

[0025] As shown in Figures 2 to 5, a support bracket 50 is fixed to one upper end of the backrest frame 40, and the millimeter-wave sensor 11 is attached to the support bracket 50. By positioning the millimeter-wave sensor 11 on the upper side of the backrest 4 at a height that faces downwards toward the seat 3, millimeter waves can be irradiated from the front toward almost the entire surface of the seat 3. The seat surface of the seat 3 refers to the upper, approximately horizontal surface of the cushion 3a that is mainly in contact with the seated person, and corresponds to the area that overlaps with the seat frame 30 in a plan view.

[0026] Furthermore, the angle of the millimeter-wave sensor 11 relative to the seat 3, that is, the angle of millimeter-wave irradiation directed toward the seat 3, can be adjusted by the support bracket 50. More specifically, as shown in Figure 2, an angle member 42 is fixed along the approximately horizontal upper end 41 of the backrest frame 40, and a support bracket 50 is attached to one end of the angle member 42 that faces outward from the seat. Here, the support bracket 50 is attached at an angle closer to the inside of the seat, such that its vertical back portion 51 faces a perpendicular line passing through the center of the seat surface of the seat 3.

[0027] <Support bracket 50> As shown in Figures 13 to 15, the support bracket 50 comprises a rear surface 51 that forms a vertical surface, a pair of side surfaces 52, 52 that are bent forward at a right angle from both ends of the rear surface 51, and a mounting surface 53 that is supported between the side surfaces 52 in a position facing the rear surface 51. The mounting surface 53 is the part on its front side to which the millimeter-wave sensor 11 is attached, and is supported so that its angle can be adjusted in the vertical direction.

[0028] Specifically, the lower edge of the mounting surface 53 is pivotally supported via a horizontal rotating shaft 54 ​​installed between each side surface 52. On the other hand, a horizontal movable shaft 55 is pivotally supported on the upper edge of the mounting surface 53. An arc-shaped guide groove 56 is formed in each side surface 52, centered on the rotating shaft 54, and both ends of the movable shaft 55 are movably fitted into the guide groove 56 of each side surface 52.

[0029] The movable shaft 55 is formed in the shape of a bolt, with one end serving as the bolt head 55a, which abuts against the guide groove 56 of one side portion 52, and the other end having a nut 55b screwed onto it, which abuts against the guide groove 56 of the other side portion 52. Therefore, by loosening the nut 55b, the mounting surface portion 53 (i.e., the millimeter-wave sensor 11) can be adjusted to any tilt angle around the rotation axis 54, and by tightening the nut 55b at the desired tilt angle, it can be fixed at that angle. The specific shape of the millimeter-wave sensor 11 itself, which is attached to the mounting surface portion 53, is well known, so a detailed explanation is omitted.

[0030] <Reflector 31> As shown in Figures 1 and 2, a reflector 31, which also serves as the seat frame 30, is provided beneath the seat surface of the cushion 3a of the seat 3. The reflector 31 is configured to receive millimeter waves transmitted from the millimeter wave sensor 11 over its entire upper surface and reflect them back towards the millimeter wave sensor 11. More specifically, as shown in Figures 6 to 9, the upper surface 30a of the seat frame 30 serves as the reflector 31, and multiple corner reflectors 32 are integrally arranged on the same plane, with their opening surfaces overlapping the upper surface 30a, and closely aligned.

[0031] As shown in Figure 10, the corner reflector 32 is a reflector made by joining three right-angled isosceles triangular metal plates. With the corner reflector 32, no matter which surface the millimeter wave is incident on, reflection is repeated within the three surfaces, and the reflected wave can be accurately reflected in the direction from which the millimeter wave was incident. In other words, the corner reflector 32 can widen the directivity of the reflected wave compared to reflectors of other shapes, and a uniform reflected wave can be obtained regardless of the incident angle of the millimeter wave. Therefore, even if the millimeter wave sensor 11 is installed on the upper side of the backrest 4 and the distance increases, causing the reflected wave to weaken, the reflection efficiency can be increased accordingly.

[0032] As shown in Figure 6, the multiple corner reflectors 32 are joined together by welding or other means at the edges of their respective openings, so that their openings are closely aligned on the same plane and form a single continuous reflective section 31. This reflective section 31 is integrated into the structure of the seat frame 30 itself so as to occupy as wide an area of ​​the upper surface 30a of the seat frame 30 as possible. In the upper surface 30a of the seat frame 30, any area where the reflective section 31 (multiple corner reflectors 32) cannot be placed remains as a horizontal, plate-like upper surface 30a.

[0033] In this embodiment, the area of ​​the upper surface 30a of the seat frame 30 into which the reflective section 31 is incorporated is pre-cut out, and the entire reflective section 31, which consists of multiple corner reflectors 32 connected together, is integrally incorporated into this area by welding or the like. Thus, the reflective section 31, which also serves as the seat frame 30, may be constructed separately and added later as part of the seat frame 30, or it may be integrally formed together with the seat frame 30 by sheet metal press molding or casting.

[0034] The specific number and arrangement of the multiple corner reflectors 32 that make up the reflective section 31 are design matters that can be determined as appropriate, not limited to the illustrated example. As shown in Figures 11 and 12, a predetermined number (five in the illustrated example) of corner reflectors 32 may be pre-arranged, for example, in a straight line and combined in advance to form a unit that constitutes the reflective section 31. The unit formed by combining the five corner reflectors 32 in a straight line as shown in Figures 11 and 12 will directly constitute the auxiliary reflective sections 31A and 31B, which will be described later, separate from the reflective section 31.

[0035] <Controller 60> As shown in Figure 16, the controller 60 consists of, for example, a microcomputer and peripheral electronic equipment, and specifically consists of a processor (CPU), non-volatile memory (ROM) for storing programs executed by the processor and various fixed data, and volatile memory (RAM) for storing data temporarily required for program execution, among other components. The controller 60 has the following functions: an input unit 61, a control unit 62, an output unit 63, a storage unit 64, and so on.

[0036] The input unit 61 receives input of various information, such as the electrical signals from the millimeter-wave sensor 11, and various other information, such as numerical values ​​specified by the operation unit 66. The control unit 62 controls the transmission of millimeter waves from the transmitter unit 12 of the millimeter-wave sensor 11 and processes the electrical signals from the millimeter-wave sensor 11 to detect wetting of the seat 1 (more precisely, the seat portion 3) based on the degree to which the signal strength is attenuated by moisture as the millimeter waves pass through the inside of the seat 1. The specific method for detecting wetting of the seat portion 3 will be described later.

[0037] The control unit 62 controls the transmission of millimeter waves from the transmitter unit 12 of the millimeter-wave sensor 11 to repeat, for example, at a predetermined period. More specifically, the control unit 62 is set to transmit millimeter waves from the transmitter unit 12 of the millimeter-wave sensor 11 at predetermined timings. Here, the predetermined timing can be determined as appropriate, for example, just before arriving at the next station where passengers disembark, or when the train arrives at the final station.

[0038] The output unit 63 outputs information regarding the wetness of seat 1 detected by the control unit 62. The output destination of the signal from the output unit 63 is mainly the display unit 65, but is not limited to the display unit 65. The memory unit 64 stores programs and various data used by the control unit 62 to detect the wetness of seat 1. Examples of such data include pre-measured values, such as the signal strength of the reflected wave when seat 1 is dry.

[0039] The display unit 65 displays the determination result regarding the wetness of seat 1 from the control unit 62. The display unit 65 may, for example, use a computer monitor as is, and will display various information, including the determination result, in a visually readable format using text, images, etc. In addition to the display by the display unit 65, sound notifications such as artificial voice or alarms may also be provided through an audio output device such as a speaker.

[0040] The operation unit 66 is operated by the user, for example, to input numerical data necessary for various processes of the control unit 62. The operation unit 66 is, for example, a computer mouse, keyboard, or touch panel. Users of the seat wetness detection device 10 can input various data required for processing by the control unit 62 or to instruct processing operations by operating this operation unit 66.

[0041] <Operation of seat wetness detection device 10> Next, we will explain how the seat 1 is detected as wet by the seat wetness detection device 10. In Figure 16, the millimeter-wave sensor 11 generates millimeter waves using a synthesizer at a predetermined timing based on a command from the control unit 62 of the controller 60, and transmits the millimeter waves from its front side toward the seat surface of the seat portion 3 below.

[0042] As shown in Figure 1, since the millimeter-wave sensor 11 is located on the upper side of the backrest 4, the distance from the millimeter-wave sensor 11 to the seat 3 is greater than, for example, if it were located on the sleeve immediately to the side of the seat 3, thus allowing for a wider irradiation range of millimeter waves to be secured for the seat 3. Furthermore, in this embodiment, the millimeter-wave sensor 11 is located on the front side 4b, away from the center of the backrest 4, so that the sitter does not feel any foreign object sensation on their head. However, it is also possible to irradiate the seat 3 with millimeter waves from an angle that is as directly facing its front as possible.

[0043] The transmitted waves from the millimeter-wave sensor 11 pass through the cushion 3a of the seat 3 and are reflected by the reflector 31, which also serves as the seat frame 30. These reflected waves pass through the cushion 3a again and return to the millimeter-wave sensor 11, where they are received by the receiver 13. As shown in Figure 6, since the reflector 31 also serves as the seat frame 30, the number of parts and assembly steps can be reduced compared to when the reflector is placed separately from the seat frame 30, thereby reducing the manufacturing cost of the seat 1.

[0044] Furthermore, the reflective section 31 is capable of receiving and reflecting millimeter waves over its entire upper surface. Therefore, it is possible to detect the degree of wetness over a wide area, such as the entire seat surface of the seat section 3. Moreover, if, for example, multiple reflectors were locally arranged within the seat section 3, it would be necessary to adjust the reflection angle of each reflector, but with the reflective section 31 of this embodiment, such troublesome work is unnecessary.

[0045] In particular, the reflective section 31 is made up of multiple corner reflectors 32 that are closely arranged on the same plane, with their respective opening surfaces overlapping the upper surface 30a of the seat frame 30. With such a reflective section 31, it is possible to increase the reflection efficiency by using individual corner reflectors 32 throughout its entire surface, and even when the distance from the millimeter-wave sensor 11 is great, a strong reflection intensity can be achieved without angle adjustment compared to a flat reflector.

[0046] Then, when the reflected wave from the reflector 31 returns to the millimeter-wave sensor 11 and is received, the millimeter-wave sensor 11 mixes the transmitted wave and the reflected wave using a mixer to generate an IF signal (intermediate frequency), and various signal processing is performed based on the data obtained from this IF signal. The electrical signal generated by the millimeter-wave sensor 11 is output to the controller 60 and stored in the memory unit 64. The electrical signal stored in the memory unit 64 is digitally converted by an AD conversion circuit or the like and stored in the memory area of ​​the control unit 62. The control unit 62 performs a process to calculate the signal strength of the reflected wave from the reflector 31 based on the electrical signal acquired from the millimeter-wave sensor 11.

[0047] Figure 16(b) is an example of a graph showing the signal intensity of the reflected wave from the reflector 31. The horizontal axis represents the optical distance from the millimeter-wave sensor 11 to the reflector 31, and the vertical axis represents the signal intensity of the reflected wave. Here, the distance on the horizontal axis is proportional to the time from the time the transmitted wave is output until the reflected wave returns, and is predetermined by the arrangement of the reflector 31. The signal intensity on the vertical axis is expressed as a relative value, and its unit is not particularly limited. The peak of the signal intensity of the reflected wave from the reflector 31 occurs at a predetermined point on the horizontal axis depending on the distance from the transmitter 12.

[0048] The chirp of the reflected wave from the reflector 31 is processed, for example, using an FFT to detect the distance to the reflector 31. Since the distance to the reflector 31 is fixed, the distance FFT corresponding to the chirp will show a peak at the same point (horizontal axis). The control unit 62 determines the wetness of the seat 1 based on the results of this graphing process. Here, the wetness of the seat 1 is synonymous with the moisture contained mainly in the cushion 3a of the seat 3.

[0049] Figure 17 shows how the millimeter waves from the millimeter-wave sensor 11 change when the seat 3 is in a normal dry state and when the seat 3 is wet for some reason. The transmitted wave from the millimeter-wave sensor 11 (transmitter 12) toward the seat 3 shows a significant difference between the initial signal strength of the transmitted wave and the signal strength of the reflected wave across the entire upper surface of the reflector 31, depending on whether it is in a "dry state" where no moisture is present or a "wet state" where moisture is present.

[0050] The [Concept] in Figure 17 schematically illustrates the state in which the transmitted wave from the millimeter-wave sensor 11 is reflected by the reflector 31 and returns as a reflected wave. As shown in the [Concept] in Figure 17(a), when the seat 3 is dry, the transmitted wave from the millimeter-wave sensor 11 passes through the cushion 3a and reaches the reflector 31 with little attenuation, and the reflected wave from the reflector 31 also returns to the millimeter-wave sensor 11 with little attenuation. On the other hand, as shown in the [Concept] in Figure 17(b), when the seat 3 is wet, the transmitted wave from the millimeter-wave sensor 11 passes through the cushion 3a and reaches the reflector 31 with considerable attenuation due to the moisture, and the reflected wave from the reflector 31 also returns to the millimeter-wave sensor 11 with further attenuation.

[0051] Thus, in a wet state, the millimeter waves emitted from the millimeter-wave sensor 11 are significantly weaker when they return to the millimeter-wave sensor 11 compared to a dry state. In other words, the inventors' experiments have confirmed that the signal strength of the reflected wave when the seat 3 is wet is significantly lower than the signal strength of the reflected wave when the seat 3 is dry. Therefore, the control unit 62 can detect the wetness of the seat 1 based on the ratio (signal ratio) of the signal strength of the reflected wave when the seat 3 is wet to the signal strength of the reflected wave when the seat 3 is dry.

[0052] The graph in Figure 17 shows the signal intensity of the reflected wave from the reflector 31. As shown in the graph in Figure 17(a), when seat 1 is dry, the peak of the reflected wave signal intensity is, for example, 5000 as a relative value. On the other hand, as shown in the graph in Figure 17(b), when seat 1 is wet, the peak of the reflected wave signal intensity is, for example, 2800 as a relative value. Thus, the signal intensity of the reflected wave is significantly attenuated in the wet state than in the dry state, and the specific degree of attenuation, in the numerical example above, is 0.56(2800 / 5000) times that of the dry state, or 44%.

[0053] The aforementioned signal ratio of 0.56 approaches 1.0 as seat 1 dries and its moisture content decreases. Based on this value, a threshold for the acceptable level of wetness of seat 1 is determined, for example, between 0.56 and 1.0. Specifically, for example, if the threshold is set to 0.8 based on data from a subjective test that perceives "wetness," then the system will determine that the seat is wet if the attenuation rate of the reflected wave signal intensity is less than 0.8. Of course, a threshold of 0.8 is merely an example, and it can be set to any other appropriate value, such as 0.5.

[0054] Such threshold settings can be adjusted as appropriate by the operation unit 66. Specifically, for example, it can be set to read the signal strength at a height Hmm on the vertical axis of the graph. Here, the height Hmm can be arbitrarily changed. Also, as will be described later, the signal strength height Hmm can be set to have a range of ±w on the horizontal axis and use the average value of that range. Here, the range ±w can also be arbitrarily changed. Furthermore, it is desirable to allow the timing and frequency YHz of reading the signal strength to be arbitrarily changed as well. Note that the comparison of peak values ​​of signal strength does not necessarily presuppose graphing.

[0055] Furthermore, it would be good to allow users to arbitrarily change the maximum and minimum values ​​(Max and Min) of the signal strength to be read. In any case, as mentioned above, the system should be configured to set a flag indicating that the seat is wet when the attenuation rate of the reflected wave signal strength falls below 1 / X (X>1). When this flag is set, the display unit 65 should display a warning such as the word "wet" indicating that seat 1 is wet, as shown in the [Monitor] section of Figure 17(b). Subsequent processing will be described later.

[0056] As described above, when determining the signal ratio of the reflected wave signal intensity in a wet state and a dry state, the calculation can be performed using the peak value or the average value over a predetermined width ±w. However, to reduce errors, the following calculation is also possible. That is, the system can be set to determine whether the seat portion 3 is wet or not based on the area ratio in a predetermined range of the graph, which includes the signal intensity within the ±w width of the horizontal axis, as mentioned above, using the peak signal intensity as the reference.

[0057] Furthermore, as another determination method, a predetermined range on the horizontal axis of the graph may be set to include the peak of the signal intensity of the reflected wave from the reflector 31 and a predetermined width before and after it, and the determination of whether the seat portion 3 is wet or not may be made based on the area ratio in the graph that falls within this predetermined range. That is, as shown in Figure 18, the determination of whether the seat portion 3 is wet may be made based on whether the ratio of the area enclosed by the quadratic curve of signal intensity when the seat portion 3 is dry and the area enclosed by the quadratic curve of signal intensity when the seat portion 3 is wet exceeds a predetermined threshold.

[0058] The specific threshold setting is the same as in the case of comparing the peak values. The calculation of the area enclosed by curves or lines (horizontal axis, etc.) representing signal strength on the graph can be done using well-known formulas, and it is advisable to program this calculation in advance. Furthermore, the area of ​​each region on the graph to be compared can be set by the operation unit 66, similar to the threshold setting.

[0059] The determination of such thresholds and predetermined ranges in the graph are design considerations that can be appropriately determined based on data from various experiments and simulations. Of course, the comparison using area ratios in the graph mentioned above does not necessarily depend on geometric processing; for example, wetness detection could be performed by comparing the integrated values ​​of signal intensity and distance data for dry and wet conditions.

[0060] <Action taken after detecting wetness in seat 3> Figure 19 is a flowchart showing an example of processing after the seat wetness detection device 10 detects wetness in the seat portion 3. When wetness in the seat portion 3 is detected by the control unit 62 of the controller 60, as described above (step S101), information regarding the seat number of the wet seat is output to, for example, the driver's cab of the vehicle (step S102).

[0061] Based on this, the information is output to the display on seat 1 (step S103), to the conductor's tablet (step S104), and also to a monitor on the ground outside the vehicle (step S111). Furthermore, based on the information output to the ground monitor, the inventory status of replacement parts (cushion 3a of seat 3) is checked (step S112).

[0062] Next, the conductor checks the actual wetness of the seat portion 3 of seat 1 displayed on the tablet (step S105). At this time, he determines whether or not the seat portion 3 needs to be replaced (step S106). If the conductor determines that the seat portion 3 needs to be replaced, he requests that the replacement part be transported to the next station, depending on the availability of replacement parts as described above (step S113). The conductor then receives the replacement part at the next station (step S107), removes the wet seat portion 3, and replaces it with a new seat portion 3 (step S108).

[0063] Incidentally, in the detection of wetting of the seat 3 mentioned above, a decision was made selectively based on whether or not the degree of attenuation of the millimeter-wave signal strength exceeded a threshold, and whether or not the seat 3 actually needed to be replaced was then determined, for example, by a human. However, it would also be possible to control the system so that the need for such replacement is determined automatically. Such control can be implemented relatively easily by changing the program in the controller 60.

[0064] In other words, the detection of wetting of the seat 3 in step S101 in Figure 19 may be controlled not by an alternative judgment of whether the degree of attenuation of the millimeter-wave signal strength is above or below a certain threshold, but by, for example, dividing the degree of attenuation of the signal strength into multiple ranks for judgment. This makes it possible to take measures such as locally drying the slightly wet areas of the seat 3 without replacing the entire seat 3 if the wetness rank is low.

[0065] <Modified example 1 of the reflective part 31> Figures 20 to 22 show a modified example 1 of the reflective section 31 according to the embodiment. In this modified example 1, in addition to the reflective portion 31 that forms the upper surface of the seat frame 30 as described above, a front auxiliary reflective portion 31A is added along the front end of the periphery of the seat frame 30. The front auxiliary reflective portion 31A is configured to receive electromagnetic waves transmitted from the millimeter-wave sensor 11 that have deviated in front of the reflective portion 31 and to reflect them back toward the millimeter-wave sensor 11.

[0066] More specifically, the front auxiliary reflector section 31A consists of a unit formed by linearly combining five corner reflectors 32 as shown in Figures 11 and 12, and is integrally connected along the front end of the seat frame 30. The connection here can be made, for example, by welding them together via a narrow, thin metal plate, or by directly fixing the open ends of the corner reflectors 32 that make up the front auxiliary reflector section 31A by welding or the like. The angle at which the front auxiliary reflector section 31A is connected can be adjusted from a state where it is horizontally aligned with the upper surface of the reflector section 31 to a state where it is bent upward toward the millimeter-wave sensor 11 on the upper side of the backrest 4.

[0067] Thus, the front auxiliary reflector 31A is constructed separately from the reflector 31 and attached to the seat frame 30 afterwards, or it may be constructed to be pre-integrated with the seat frame 30 or the reflector 31. In the latter case, the total number of parts and assembly man-hours for the seat 1 are reduced. In either configuration, it is preferable that the front auxiliary reflector 31A be adjustable to the optimal angle toward the millimeter-wave sensor 11. The specific length and size of the front auxiliary reflector 31A, i.e., the number and arrangement of the corner reflectors 32, are design matters that can be determined as appropriate.

[0068] In Figure 1, there is a distance equal to the thickness of the cushion 3a from the seat surface of the seat portion 3 to the reflector portion 31 below it. Therefore, a portion of the periphery of the seat portion (front edge and side edge) located above the irradiation angle from the millimeter-wave sensor 11 to the reflector portion 31 will be outside the millimeter-wave transmission and reception route. By providing a front auxiliary reflector portion 31A on the front edge of the seat portion frame 30 and extending the millimeter-wave transmission and reception route, it becomes possible to detect wetting in a portion of the periphery of the seat portion 3 corresponding to that area without any omissions.

[0069] As mentioned above, the millimeter-wave sensor 11 also has the function of acquiring positional information of an object (reflector 31, etc.), so it can distinguish between reflected waves from the reflector 31 and the front auxiliary reflector 31A and generate electrical signals corresponding to the signal strength of each. Therefore, when the signal strengths of the reflected waves from each reflector 31, 31A are represented on the same graph, for example, as shown in Figure 22, the peaks of the signal strength for each reflector 31, 31A will occur at different points on the horizontal axis depending on the distance from the millimeter-wave sensor 11. This makes it possible to determine the wetness of the seat 3 all the way to the front end of the seat surface by comparing the peaks of the signal strength of the reflected waves and the area ratios in the graph for each route within the cushion 3a leading to each reflector 31, 31A.

[0070] <Modified example 2 of the reflective section 31> Figures 23 to 25 show yet another modified example 2 of the reflective section 31 according to the embodiment. In this modified example 2, in addition to the aforementioned reflector 31 and front auxiliary reflector 31A, a pair of side-end auxiliary reflectors 31B1 and 31B2 are added along both ends of the periphery of the seat frame 30. The side-end auxiliary reflectors 31B1 and 31B2 are configured to receive electromagnetic waves transmitted from the millimeter-wave sensor 11 that have deviated to the side of the reflector 31, and to reflect them back toward the millimeter-wave sensor 11.

[0071] More specifically, the side-end auxiliary reflectors 31B1 and 31B2, like the front-end auxiliary reflector 31A, consist of a unit formed by linearly combining the five corner reflectors 32 shown in Figures 11 and 12, and are integrally connected along the side ends of the seat frame 30. The side-end auxiliary reflectors 31B1 and 31B2 can be configured separately from the reflector 31 and attached to the seat frame 30 afterwards, or they can be configured to be integrally provided with the seat frame 30 or the reflector 31 from the beginning. Furthermore, it is preferable that the side-end auxiliary reflectors 31B1 and 31B2 be configured to be adjustable to the optimal angle toward the millimeter-wave sensor 11.

[0072] Even when such auxiliary side reflectors 31B1 and 31B2 are added, if the signal strength of the reflected waves from each reflector 31, 31A, 31B1, and 31B2 is represented on the same graph, the peak signal strength for each reflector 31, 31A, 31B1, and 31B2 will occur at different points on the horizontal axis depending on the distance from the millimeter-wave sensor 11, as shown in Figure 25, for example. This makes it possible to determine the wetness of the seat 3 thoroughly and completely, including the front and both sides of the seat surface, by comparing the peak signal strength of the reflected waves and the area ratios in the graph for each route within the cushion 3a leading to each reflector 31, 31A, 31B1, and 31B2.

[0073] <Construction and Effects of the Invention> Although this embodiment has been described above, the present invention is not limited to the embodiments described above. The present invention derived from the embodiments described above will be described below.

[0074] First, the present invention relates to a seat wetness detection device 10 for detecting wetness of seat 1, A sensor 11 is provided at a height overlooking the seat portion 3 of seat 1, and transmits electromagnetic waves from the front towards the seat surface of the opposing seat portion 3, and receives the reflected waves that are reflected back from the front. It comprises a reflective section 31 that is provided within the seat section 3 so as to overlap the seat surface in a plan view, and which also serves as the seat frame 30 within the seat section 3, The reflective portion 31 is capable of receiving electromagnetic waves transmitted from the sensor 11 over its entire upper surface and reflecting them back toward the sensor 11. The system is characterized by its ability to determine whether the seat portion 3 is wet based on the degree of attenuation of the signal intensity due to moisture in the reflected wave received by the sensor 11.

[0075] With this type of seat wetness detection device 10, the sensor 11 is positioned at a height that faces downwards towards the seat portion 3 of the seat 1, so that electromagnetic waves can be transmitted from the front towards the entire seat surface of the seat portion 3. Moreover, the distance from the sensor 11 to the seat surface is relatively far, so a wide range of electromagnetic wave irradiation can be secured.

[0076] Furthermore, since the reflective section 31 that reflects electromagnetic waves from the sensor 11 also serves as the seat frame 30, the number of parts and assembly steps can be reduced compared to the case where the reflective section 31 is provided separately from the seat frame 3, thereby reducing costs. In addition, the reflective section 31 can receive electromagnetic waves and reflect them back towards the sensor 11 across its entire upper surface. Therefore, troublesome work such as adjusting the reflection angle of the reflective section 31 is unnecessary.

[0077] In the seat wetness detection device 10, the wetness of the seat 3 is determined based on the degree to which the signal strength of the reflected wave from the reflector 31, which covers a wide area of ​​the seat 3, is attenuated by moisture as it passes through the seat 3 in response to the transmitted wave from the sensor 11 positioned at a high position. In this determination, the wetness of the seat 3 can be detected more easily and accurately over an even wider area.

[0078] Furthermore, in the present invention, the seat frame 30 is formed in a panel shape, and the upper surface of the seat frame 30 is the reflective portion 31, in which a plurality of corner reflectors 32 are integrally connected in such a manner that their respective opening surfaces are closely arranged on the same plane.

[0079] With the reflective portion 31 of the seat frame 30, the reflection efficiency can be increased by the individual corner reflectors 32 throughout its entire surface. This allows for a strong reflection intensity to be achieved even at a greater distance from the sensor 11, without the need for fine adjustments to the angle or other parameters, compared to a flat reflector.

[0080] Furthermore, the present invention is characterized by providing auxiliary reflective portions 31A, 31B1, and 31B2 that are added to the reflective portion 31 along at least a portion of the periphery of the seat frame 30, and that receive electromagnetic waves transmitted from the sensor 11 that have deviated from the reflective portion 31 and reflect them toward the sensor 11.

[0081] Since these auxiliary reflective sections 31A, 31B1, and 31B2 extend outward from the periphery of the seat frame 30, they can reliably receive and reflect electromagnetic waves that pass through the seat 3 but miss the reflective section 31. Therefore, it is possible to reliably detect wetting of the part of the seat surface of the seat 3 that continues to the end. The auxiliary reflective sections 31A, 31B1, and 31B2 may be constructed separately from the reflective section 31 and added later as needed, or they may be constructed integrally with the reflective section 31 from the beginning to reduce the number of parts and assembly time.

[0082] Furthermore, in the present invention, the sensor 11 is provided on the upper side of the backrest 4 which is supported on the rear end side of the seat portion 3.

[0083] In this way, by placing the sensor 11 on the upper side of the backrest 4, the distance from the sensor 11 to the seat surface of the seat 3 is greater than, for example, if it were placed on the armrest immediately to the side of the seat 3, thus allowing for a wider range of electromagnetic wave irradiation to be secured for the seat 3. Here, it is also possible to irradiate the seat surface of the seat 3 from an angle as close as possible to the front side. Furthermore, the sensor 11 can be assembled and finished as a single component within the scope of a single seat 1 product.

[0084] Furthermore, in the present invention, the sensor 11 is attached to the backrest frame 40 within the backrest 4 via a support bracket 50 that allows adjustment of the irradiation angle of electromagnetic waves from the front side toward the seat 3. This makes it easy to adjust the irradiation range of the electromagnetic waves transmitted from the sensor 11 so that it overlaps with the entire seat surface of the seat portion 3, which is located directly below and in front of the seat 1, according to the various design specifications of the seat 1.

[0085] Furthermore, in the present invention, the determination of whether the seat portion 3 is wet is made by determining whether the ratio of the peak value of the reflected wave signal intensity reflected from the reflecting portion 31 and received by the sensor 11, when the seat portion 3 is dry, to the peak value when the seat portion 3 is wet, exceeds a predetermined threshold. By making a determination based solely on the numerical comparison of the peak signal strength, the wetness of seat 1 can be determined with extremely simple control.

[0086] Furthermore, in the present invention, the determination of whether the seat portion 3 is wet is made by determining whether the ratio of the area enclosed by the quadratic curve representing the signal strength when the seat portion 3 is dry to the area enclosed by the quadratic curve representing the signal strength when the seat portion 3 is wet exceeds a predetermined threshold, in a graph representing the signal strength of the reflected wave reflected from the reflecting portion 31 and received by the sensor 11. By using this method of determining signal strength by comparing the area of ​​a quadratic curve, the variation in measurement accuracy in determining whether seat 1 is wet can be reduced, further improving the accuracy of the detection results.

[0087] Furthermore, the present invention is characterized by comprising a display unit 65 that displays the result of determining whether the seat portion 3 is wet. This allows the display unit 65 to easily provide information regarding the wetness determination result of seat 1. Therefore, anyone who sees the display can more easily take measures regarding the wetness of seat 1.

[0088] Although this embodiment has been described above with reference to the drawings, the specific configuration is not limited to these embodiments, and any changes or additions that do not depart from the spirit of the present invention are also included. For example, the seat 1 to be detected by the seat wetness detection device 10 is not necessarily limited to seats installed in the passenger compartment of a railway vehicle, but may also be seats for other vehicles such as aircraft, buses, and ships, or the seat portion of seats installed in movie theaters, theaters, etc.

[0089] Furthermore, the placement of the millimeter-wave sensor 11 is not limited to the backrest 4 of seat 1, but could also be placed on the back of the backrest of another seat located in front of seat 1, or on the ceiling or overhead rack of the vehicle. Also, the electromagnetic waves used in this invention are not necessarily limited to millimeter waves. Moreover, the shape and size of the reflecting part 31 and the auxiliary reflecting parts 31A and 31B, as well as their specific arrangement, angles, and number, are not limited to the embodiments described above. [Industrial applicability]

[0090] This invention is not limited to seats installed in the passenger compartments of various vehicles such as railway cars, aircraft, automobiles, and ships, but can also be broadly applied to seats installed in movie theaters, theaters, and the like. [Explanation of symbols]

[0091] 1… Seat 2…Step stool 3… Seat part 4...backrest 10…Seat wetness detection device 11…Millimeter-wave sensor 30...Seat frame 31…Reflector 31A…Front end auxiliary reflector 31B…Side end auxiliary reflector 50…Support bracket 60… Controller 61...Input section 62... Control Unit 63…Output section 64...Storage section 65...Display section 66…Operations Department

Claims

1. A seat wetness detection device for detecting wetness on a seat, A sensor is installed at a height that looks downward from the seat portion of the seat, and transmits electromagnetic waves from the front towards the seat surface of the opposite seat, and receives the reflected waves that are returned from the front. It comprises a reflective section provided on the same plane as the seat surface in a plan view, and which also serves as the seat frame within the seat, The reflective portion is capable of receiving electromagnetic waves transmitted from the sensor over its entire upper surface and reflecting them back toward the sensor. Based on the degree of attenuation of the signal intensity due to moisture in the reflected wave received by the aforementioned sensor, it is possible to determine whether the seat is wet. The seat frame is provided with an auxiliary reflective portion attached to the reflective portion, extending outward from a portion of the periphery of the seat frame, The seat wetness detection device is characterized in that the auxiliary reflective section is capable of adjusting its angle to receive electromagnetic waves that have passed through a part of the periphery of the seat located above the irradiation angle of the electromagnetic waves transmitted from the sensor to the reflective section and have deviated from the reflective section, and to reflect them toward the sensor, thereby enabling the detection of wetness in a part of the periphery of the seat via a different route than that between the sensor and the reflective section.

2. The seat wetness detection device according to claim 1, characterized in that the seat frame is formed in a panel shape, and a plurality of corner reflectors are integrally connected on the upper surface of the seat frame as the reflective part, with their respective opening surfaces closely arranged on the same plane.

3. The seat wetness detection device according to claim 1, characterized in that the sensor is provided on the upper side of the backrest supported on the rear end side of the seat.

4. The seat wetness detection device according to claim 3, characterized in that the sensor is attached to the backrest frame within the backrest via a support bracket that allows adjustment of the irradiation angle of electromagnetic waves from the front side toward the seat.

5. The seat wetness detection device according to claim 1, characterized in that the determination of whether the seat is wet is made by determining whether the ratio of the peak value of the reflected wave signal intensity when the seat is dry to the peak value when the seat is wet exceeds a predetermined threshold, based on the signal intensity of the reflected wave reflected from the reflecting part and the auxiliary reflecting part and received by the sensor.

6. The seat wetness detection device according to claim 1, characterized in that the determination of whether the seat is wet is made by determining whether the ratio of the area enclosed by the quadratic curve representing the signal intensity when the seat is dry to the area enclosed by the quadratic curve representing the signal intensity when the seat is wet exceeds a predetermined threshold, in a graph representing the signal intensity of the reflected waves reflected from the reflecting part and the auxiliary reflecting part and received by the sensor.

7. The seat wetness detection device according to claim 1, 2, 3, 4, 5, or 6, further comprising a display unit for displaying the result of determining the wetness of the seat.

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