Perceptron

Abstract

A sensor is provided with: a shield case made of a conductive resin material, the shield case holding a detection element therein; and a substrate assembly that is disposed on one surface of the shield case and holds an amplification circuit that amplifies a signal from the detection element and an output antenna. The substrate assembly has a conductive ground conductor film that blocks one surface of the shield case, the ground conductor film being electrically connected to the shield case, and the output antenna being electrically connected to the ground conductor film. The shielding space is formed by the shielding shell and the grounding conductor film, and the detection element and the amplification circuit are arranged in the space, so that the electromagnetic wave resistance performance can be improved, and the grounding conductor film and the shielding shell of the substrate assembly can be used for grounding of the output antenna. A detection element and an amplification circuit are protected from an electromagnetic wave environment.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a sensor. The sensor of the present disclosure is useful, for example, as a smoke sensor installed near an electrical wiring or a transformer with high risk of fire in a factory. BACKGROUND

[0002] A smoke sensor provided with an output antenna is disclosed in Patent Literature 1 and Patent Literature 2.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Application Laid-Open No. 2023-59947

[0006] Patent Literature 2: Japanese Patent Application Laid-Open No. 2014-170274 SUMMARY

[0007] The smoke sensor shown in Patent Literature 1 uses a metal-made lead wire to secure grounding of the output antenna. Also, the smoke sensor shown in Patent Literature 2 uses a metal-made insect screen to secure grounding of the output antenna. However, these merely secure grounding of the output antenna. Therefore, none of the documents studies electromagnetic wave resistance of electronic components.

[0008] In view of the above, an object of the present disclosure is to protect a detection element as a sensor of a sensor and an amplification circuit that amplifies a signal detected by the detection element from an electromagnetic wave environment.

[0009] The sensor of the present disclosure is provided with a first case made of a non-conductive resin material, which is installed at a detection site, and a second case made of a non-conductive resin material, which is installed at the first case. Also, the sensor of the present disclosure is provided with a shield case made of a conductive material, which is arranged between the second case and the first case, has a container shape with one face opened, and holds a detection element inside the container shape. Also, a substrate assembly, which holds an amplification circuit, a control section, a transmission section, and an output antenna, is arranged at one face of the shield case, the amplification circuit amplifies a signal detected by the detection element, the control section controls the detection element, and the transmission section transmits a notification signal determined by the control section based on the signal detected by the detection element to the outside.

[0010] The substrate assembly of the sensor of the present disclosure has a conductive ground conductor film that extends at one face of the shield case, and the ground conductor film is in conduction with the shield case. Also, the amplification circuit is arranged at the shield case side of the ground conductor film. Furthermore, the output antenna uses the ground conductor film and the shield case as a ground.

[0011] According to the present disclosure, a shield case made of an electrically conductive resin material and an electrically conductive ground conductor film form a shield space. Also, in the shield space, a detection element and an amplification circuit are arranged. Therefore, with the sensor of the present disclosure, it is possible to improve the electromagnetic wave resistance performance. For example, even if installed near an electric wiring or a transformer, it is possible to have sufficient electromagnetic wave resistance performance.

[0012] Further, according to the present disclosure, it is possible to use the ground conductor film and the shield case of the substrate assembly for the ground of the output antenna. Thus, with the sensor of the present disclosure, it is possible to improve the radiation efficiency of the output antenna.

[0013] In a case where the sensor of the present disclosure is used as a smoke sensor, a pedestal fixed to a detection site of a building is further provided. Also, the first case is mounted to the pedestal. The second case is configured to form a smoke detection space inside, and to introduce smoke into the smoke detection space and shield external light. In addition, the detection element has a light emitting element that projects light toward the smoke detection space, and a light receiving element that detects light projected from the light emitting element and scattered in the smoke detection space. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 is a perspective view of a smoke sensor of the present example.

[0015] Figure 2 is a perspective view showing the smoke sensor exploded.

[0016] Figure 3 is a front view showing a substrate assembly and a shield case of the smoke sensor.

[0017] Figure 4 is a sectional view along the IV-IV line of Figure 3 .

[0018] Figure 5 is a perspective view showing a substrate assembly and a shield case of the smoke sensor.

[0019] Figure 6 is a circuit diagram showing an amplification circuit of the smoke sensor.

[0020] Figure 7 is a front view showing a mounting surface of the substrate assembly of the smoke sensor, shown exploded.

[0021] Figure 8 is a front view showing a ground conductor film of the substrate assembly of the smoke sensor, shown exploded.

[0022] Figure 9 is a front view showing a circuit surface of the substrate assembly of the smoke sensor, shown exploded.

[0023] Figure 10 is a perspective view of a substrate assembly of a smoke sensor.

[0024] Figure 11 is a perspective view showing a configuration state of a smoke sensor. Figure 9 is a front view of an amplification circuit composed of the illustrated circuit surface.

[0025] Figure 12 is a perspective view showing a configuration state of a smoke sensor.

[0026] Figure 13 is a perspective view showing a disassembly of another example of a smoke sensor.

[0027] Figure 14 is a perspective view showing a third housing of an example in Figure 12

[0028] Figure 15 is a graph illustrating directivity of an antenna.

[0029] Figure 16 is a graph showing a relationship between presence or absence of a metal plate and antenna performance. DETAILED DESCRIPTION

[0030] An example of using the sensor of the present disclosure as a smoke sensor 100 is shown in Figure 1 The smoke sensor 100 is installed, for example, near an electrical wiring or a transformer in a factory where a fire risk is high. Thus, the smoke sensor 100 is installed in a place where electromagnetic wave resistance is required. The smoke sensor 100 has a size that can be held by a worker with one hand. The smoke sensor 100 has a cylindrical shape with a diameter of about 50 mm and a height of about 45 mm. The total weight is about 50 g.

[0031] In Figure 2 The smoke sensor 100 is shown in a disassembled state. A base 110, a first housing 120, and a second housing 130 are arranged in this order from the top. The base 110 is made of a non-conductive resin material, for example, an ABS resin (acrylonitrile butadiene styrene resin). The base 110 is formed in a disc shape by injection molding of the ABS resin. As described above, the diameter is about 50 mm. The base 110 is fixed to a detection site using a screw or double-sided tape. In most cases, the detection site is usually a ceiling of a building. However, in a building of a factory, in most cases, an air outlet is provided in the ceiling, and air is supplied downward from the air outlet. Thus, in the event of a fire, smoke hardly reaches the ceiling, and the fire can have progressed to a considerable extent in a state where smoke fills the vicinity of the ceiling.

[0032] The smoke sensor 100 of the present example is not arranged on the ceiling of a building of a factory, but is arranged on a production line. Specifically, as shown in​Figure 12 As shown, the control box 200 is disposed in an electrical wiring set, or a transformer housing. Alternatively, it is disposed in a safety housing of a production line that houses a cutting machine or a welding machine. These are closed spaces that will be filled with smoke at an early stage once a fire breaks out. Therefore, the base 110 is not fixed to a ceiling, but to a top plate 201 of the space such as the control box 200. Therefore, the detection site of the present example is in the vicinity of a hypothetical smoke generation source. The top plate 201 needs to be processed by screw fastening, and therefore the base 110 of the present example is mainly fixed to the top plate 201 by double-sided tape.

[0033] Note that, in Figure 12 addition to the example of being fixed to the top plate 201, an example of being fixed to a side wall 202 is shown. However, two smoke sensors 100 are not usually provided in one control box 200. Figure 13 The case of being fixed to the side wall 202 is shown for the purpose of explaining a configuration example. As Figure 13 shown, in the case of fixing the smoke sensor 100 to the side wall 202, it is desirable to be fixed to a position above. In addition, in the control box 200, a fan 203 for heat dissipation is usually provided, and therefore it is desirable to be disposed in a position near the fan 203 and affected by the air flow generated by the fan 203.

[0034] Usually, several tens to about 200 smoke sensors 100 are provided on one production line. Each smoke sensor 100 is provided with a transmission unit 142 described later. Signals from each smoke sensor 100 are transmitted to a receiver provided in the production line by wireless means. The signals from each smoke sensor 100 received by the receiver are transmitted to a management server provided at a location away from the production line via a communication line such as a cloud system of the Internet and / or an intranet. The communication line such as the cloud system includes wired and / or wireless.

[0035] Like the base 110, the first housing 120 is also made of a non-conductive resin material. The first housing 120 is also formed by injection molding of ABS resin. The first housing 120 holds a battery 121 inside. Specifically, the battery holding claw formed in the first housing 120 is elastically deformed, and the battery 121 is held by the elasticity thereof. The battery 121 is electrically connected to a power supply connector 145 formed in a substrate assembly 140 described later. Through the power supply connector 145, a negative electrode terminal is electrically connected to a ground conductor film 1402, and a positive electrode terminal is electrically connected to a power supply conductor film 1403. In the present example, a 3-volt battery 121 is used. The first housing 120 is fitted to the snap claw 111 of the base 110. By turning in cooperation with the base 110, the first housing 120 can be fixed to the base 110 or detached.

[0036] The second case 130 is also made of a non-conductive resin material, and is formed by injection molding of ABS resin. The second case 130 is fixedly connected to the first case 120 by the fixing claws. Thus, the mounting of the above-described first case 120 to the base 110 is such that all the structural members of the smoke sensor 100, including the battery 121, which are held between the first case 120 and the second case 130, are fixed to or detached from the base 110.

[0037] The second case 130 is in a cylindrical shape with a closed lower end, and the lower end is in a hemispherical shape. On the side surface of the cylindrical shape of the second case 130, a plurality of introduction windows 131 are formed at equal intervals in the circumferential direction, and the introduction windows 131 introduce the smoke flowing in the vicinity of the ceiling of the closed space. In the present example, the introduction windows 131 are formed at 14. In the center position of the hemispherical shape of the lower end of the second case 130, a smoke detection space 132 is formed. The introduction windows 131 are connected to the smoke detection space 132 so that the smoke introduced from the introduction windows 131 flows into the smoke detection space 132. However, between the introduction windows 131 and the smoke detection space 132, a plurality of labyrinth walls 133 are provided. In the present example, the labyrinth walls 133 are formed at 16. Thus, the external light reaches the smoke detection space 132 is blocked by the labyrinth walls 133. That is, the labyrinth walls 133 shield the external light. However, as the shielding, it is not required to reach 100% shielding of the external light. In the present disclosure, the shielding of the external light means the blocking of the entry of the external light in an amount that adversely affects the light-receiving element 152.

[0038] Between the first case 120 and the second case 130, a substrate assembly 140, a shield case 150, and an insect screen 160 are provided. The shield case 150 is made of a conductive resin material. The shield case 150 is, for example, injection molded with a resin material in which CF30 resin (carbon fiber reinforced resin) is blended in PA6 resin (6 nylon resin). The shield case 150 is in a container shape with one open side, and the light-emitting element 151 and the light-receiving element 152 are held inside the container shape. More specifically, as shown in Figure 4 The light-emitting element 151 and the light-receiving element 152 are held by the shield case 150 at positions where they face the smoke detection space 132. In the smoke sensor 100, the light-emitting element 151 and the light-receiving element 152 function as detection elements of the sensor. Note that the detection elements of the smoke sensor 100 can also be provided by a chemical gas sensor that detects the components of a gas.

[0039] The light-emitting element 151 is an LED that projects light toward the smoke detection space 132, for example, light of an amount of about 20 milliwatts. As shown in Figure 4As shown, in the shielding housing 150, a light-emitting holding groove 156 is formed between the light-emitting element 151 and the smoke detection space 132, through which light projected from the light-emitting element 151 passes. The light-emitting holding groove 156 has a width of about 4 mm, and the light from the light-emitting element 151 reaches the smoke detection space 132 from the light-emitting holding groove 156.

[0040] The light-receiving element 152 is a photodiode that detects the scattered light when smoke enters the smoke detection space 132 and light projected from the light-emitting element 151 diffuses through the smoke. Figure 4 As shown, in the shielding housing 150, a light-receiving holding groove 1542 is formed between the light-receiving element 152 and the smoke detection space 132, allowing light emitted from the smoke detection space 132 to pass through towards the light-receiving element 152. The light-receiving holding groove 1542, like the light-projection holding groove 156, has a groove width of approximately 4 mm. It should be noted that the light-receiving element 152 is positioned separate from the optical axis of the light-emitting element 151. That is, the light-receiving element 152 does not directly detect the projected light from the light-emitting element 151, but rather detects the scattered light diffused by the smoke. Since the scattered light diffused by the smoke is weak, the output signal of the light-receiving element 152 is a weak current of approximately a few nanoamps.

[0041] As described above, since the shielding housing 150 is made of a conductive resin material, the light-emitting element 151 is held in a light-emitting element support 153 made of ABS resin, which is a non-conductive resin material. Through this light-emitting element support 153, the light-emitting element 151 is electrically insulated from the shielding housing 150 and the substrate assembly 140. Similarly, the light-receiving element 152 is also held in a light-receiving element support 154 made of ABS resin, which is a non-conductive resin material, and is electrically insulated from the shielding housing 150 and the substrate assembly 140. The light-emitting element support 153 is held in the aforementioned light-projection holding groove 156. Additionally, the light-receiving element support 154 is held in the light-receiving holding groove 1542. A light-projection hole 1531 is provided in the light-emitting element support 153, allowing light projected from the light-emitting element 151 to pass through the smoke detection space 132. The light-projection hole 1531 is a circular hole with a diameter of approximately 3 mm. Similarly, a light-receiving hole 1541 is provided in the light-receiving element support 154, allowing scattered light to pass through towards the light-receiving element 152. The optical receiving aperture 1541 is also a circular aperture with a diameter of about 3 mm.

[0042] It should be noted that the light-emitting element 151 and the light-receiving element 152 include both conductive metal encapsulation and electrically insulating resin encapsulation. In this example, the light-emitting element 151 and the light-receiving element 152 are encapsulated in a metal package, which offers excellent performance and reliability. Therefore, the light-emitting element support 153 and the light-receiving element support 154, made of ABS resin, are used to ensure electrical insulation. However, resin-encapsulated light-emitting element 151 and the light-receiving element 152 can also be used. In the case of resin encapsulation, since it is electrically insulating itself, the ABS resin light-emitting element support 153 and the light-receiving element support 154 are not required.

[0043] The substrate assembly 140 is disposed on the side of the shielding housing 150 that serves as an opening. For example... Figure 3 , Figure 5 and Figure 10 As shown, the substrate assembly 140 houses the control unit 141, the transmitter 142, the output antenna 143, the notification LED 146, and the power connector 145. The control unit 141 is a single-chip microcomputer including a CPU that controls the light-emitting element 151 and the light-receiving element 152, and it internally includes a temperature sensor. Additionally, the control unit 141 monitors the remaining power of the battery 121. The transmitter 142 is a communication module that transmits signals to the outside and internally includes a transmission circuit. The transmitted signals include a stable signal and a notification signal. The notification signal is a signal indicating the possibility of a fire, transmitted by the control unit 141 if the signal detected by the light-receiving element 152 is above a predetermined threshold. The notification LED 146 illuminates when the notification signal is output. As described above, the smoke detector 100 in this example is configured in an enclosed space, but since safety shields or the like are visible from the outside, the illumination of the notification LED can notify the surrounding area of ​​the occurrence of a fire. Figure 10 As shown, the notification LED 146 is mounted on the same surface as the control unit 141. On the other hand, the light-emitting element 151 and the light-receiving element 152 are mounted on the surface opposite to the surface on which the control unit 141 is mounted.

[0044] The output antenna 143 is a monopole antenna, using copper wire insulated with polyethylene resin. The length of the output antenna 143 is determined based on the output frequency. To improve diffraction and reachability, the wireless transmission frequency used in the factory is lower than the frequency (2.4 GHz) used in WIFI and Bluetooth (registered trademark). The frequency used in this example is, for example, 920 MHz. A lower frequency results in a longer wavelength of the radio wave, and correspondingly, the length and surface area of ​​the output antenna 143 need to be ensured. In this example, the length of the output antenna 143 is set to approximately 80 mm. It should be noted that the reason for using a monopole antenna for the output antenna 143 in this example is that monopole antennas can be miniaturized more than dipole antennas. However, in this disclosure, as explained later, sufficient grounding of the output antenna 143 is ensured. Therefore, in the output antenna 143 of this example, grounding can function as a second antenna of a dipole antenna. Therefore, although the output antenna 143 of this example is a monopole antenna, it is designed to approach the performance of a dipole antenna.

[0045] like Figure 7 , Figure 8 , Figure 9 and Figure 11 As shown, the substrate assembly 140 has a four-layer structure consisting of three insulating substrates, namely a first insulating substrate 1405, a second insulating substrate 1406 and a third insulating substrate 1407. Figure 7 The upper surface of the first insulating substrate 1405, i.e., the first layer, is shown. The first layer is the mounting surface 1401 for mounting the control unit 141 (CPU, etc.), the transmitter 142 (communication module), the notification LED 146, and the power connector 145.

[0046] The second layer of the substrate assembly 140 is a power conductor film sandwiched between a first insulating substrate 1405 and a second insulating substrate 1406. Although not shown in the figure, Figure 7 The back and Figure 8 The back side is a second layer. In this second layer, a power conductor film is formed using copper foil approximately 18 micrometers thick, located in roughly the same position as the ground conductor film 1402 described later. Furthermore, as described above, the power conductor film is electrically connected to the positive terminal of the battery 121 via a power connector 145, supplying power from the positive terminal of the battery 121. The light-emitting element 151, the light-receiving element 152, and the notification LED 146 are also electrically connected to this power conductor film 1403, receiving power from it.

[0047] The third layer of the substrate assembly 140 is a grounding conductor film 1402 formed by being sandwiched between a second insulating substrate 1406 and a third insulating substrate 1407. This grounding conductor film 1402 is made of a conductive metal material such as copper foil, and its thickness is approximately 18 micrometers, the same as the power conductor film. Additionally, as...Figure 8 As shown, a grounding conductor film 1402 is formed on a substantially entire surface of the substrate assembly 140. More specifically, the grounding conductor film 1402 is divided into multiple island-shaped regions having slit-like gaps extending in a linear fashion. The reason for dividing it into multiple islands is to separate the grounding conductor film 1402 for analog circuits from the grounding conductor film 1402 for digital circuits, making it difficult for noise to propagate.

[0048] Because the grounding conductor film 1402 is formed on approximately the entire surface of the substrate assembly 140, the substrate assembly 140 has a grounding conductor film 1402 extending onto one side of the shielding housing 150. As a result of extending onto one side of the shielding housing 150, one side of the shielding housing 150 is sealed off by the grounding conductor film 1402. Figure 5 As shown, the substrate assembly 140 is fixed to the shielding housing 150 at two points by fasteners 144 made of conductive metal. The fasteners 144 are screws made of ferrous material, and the grounding conductor film 1402 conducts electricity to the shielding housing 150 through these fasteners 144. That is, a space enclosed by the grounding conductor film 1402 and the shielding housing 150 is formed, and this enclosed space becomes a shielding space, which is shielded from electromagnetic waves. The grounding conductor film 1402 is electrically connected to the negative terminal of the battery 121 through a power connector 145. It should be noted that "one side of the shielding housing 150" is also referred to as the open end formed by the open edge of the shielding housing 150, which can also be described as container-shaped or bottomed cylindrical.

[0049] The fourth layer of the substrate assembly 140 is for the amplifier circuit 170 ( Figure 6 As shown, the circuit surface 1404 is mounted on a circuit surface where the amplifier circuit 170 amplifies the signal detected by the photoreceiving element 152. Therefore, although this circuit surface 1404 is also a mounting surface, in this example, the first layer for mounting the control unit 141, etc., is designated as the mounting surface 1401, and the fourth layer for mounting the amplifier circuit is designated as the circuit surface 1404. Figure 9 As shown, circuit surface 1404 is located on the lower surface of the third insulating substrate 1407. On circuit surface 1404, in addition to the amplifier circuit 170, a power supply conductor film is printed with positive terminal wiring connecting to the positive terminals of the light-emitting element 151 and the light-receiving element 152. Additionally, on circuit surface 1404, a ground conductor film 1402 is printed with negative terminal wiring connecting to the negative terminals of the light-emitting element 151 and the light-receiving element 152. Furthermore, signal lines for the light-receiving element 152 are also printed on circuit surface 1404.

[0050] Although Figure 11 Showing with Figure 9 The same circuit plane 1404, but with Figure 9 In contrast, the light-emitting element 151 and the light-receiving element 152 have been disassembled. Therefore, in Figure 11An amplifier circuit 170 is installed in the area enclosed by the dotted line. The circuit surface 1404 for the amplifier circuit 170 is positioned on the side of the shielding housing 150 of the grounding conductor film 1402. More specifically, it is located within the shielded space enclosed by the grounding conductor film 1402 and the shielding housing 150. The signal lines of the amplifier circuit 170 and the photodetector 152 formed on the circuit surface 1404 are sensitive to electromagnetic noise. As in this example, electromagnetic shielding is effectively achieved by being located within an enclosed space.

[0051] like Figure 6 As shown, the amplifier circuit 170 in this example includes a current-to-voltage conversion circuit 171 and a voltage amplifier circuit 175. The current-to-voltage conversion circuit 171 includes a first capacitor 172, a first resistor 173, and a first operational amplifier 174. Using the current-to-voltage conversion circuit 171, the output current of approximately a few nanoamps from the photodetector 152 is amplified to a voltage approximately 1,000,000 times its original value. The voltage amplifier circuit 175 also includes a second capacitor 176, a second resistor 177, and a second operational amplifier 178. The voltage from the current-to-voltage conversion circuit 171 is amplified to approximately 300 times its original value. For example, the output current of approximately a few millivolts from the current-to-voltage conversion circuit 171 is amplified to approximately 1 volt by the voltage amplifier circuit 175. Therefore, the control unit 141 determines whether to send a notification signal based on the signal from the photodetector 152 amplified by the amplifier circuit 170.

[0052] The output antenna 143 has a straight portion 1431 extending vertically from the transmitting portion 142 of the substrate assembly 140, and an arcuate portion 1432 along an antenna fixing groove formed on the inner circumferential surface of the first housing 120. Therefore, in this example, "arcuferically arranged along the inner circumference" means arranged along an antenna fixing groove formed on the inner circumferential surface of the generally circular first housing 120. However, the arcuate shape is not limited to a precise circle; any shape bent into an arc is acceptable. The straight portion 1431 is connected to the transmitting portion 142. The grounding of the transmitting portion 142 is electrically connected to the grounding conductor film 1402 through vias formed on the first insulating substrate 1405 and the second insulating substrate 1406, and is fixed to the first insulating substrate 1405 by solder. As described above, the grounding conductor film 1402 is electrically connected to the shielding housing 150. Therefore, the output antenna 143 is conductive to the grounding conductor film 1402 and the shielding housing 150 of the substrate assembly 140, using the grounding conductor film 1402 and the shielding housing 150 as ground. Therefore, as described above, by making the ground function as a second antenna, the radiation efficiency of the output antenna 143 can be improved.

[0053] Furthermore, since the electrical connection between the grounding conductor film 1402, implemented by the fixing member 144, and the shielding housing 150 is provided at two points, the performance as electromagnetic wave shielding can be improved. That is, if the fixing member 144 is only connected at one point, the grounding conductor film 1402 and the shielding housing 150 may act as a slot antenna, thus becoming a source of noise inflow. In contrast, if it is connected at two points, it becomes a ground plane sealed by the grounding conductor film 1402 and the shielding housing 150, which can effectively prevent noise inflow. In addition, by increasing the number of grounding connection points, the impedance between the shielding housing 150 and the grounding conductor film 1402 will decrease. As this impedance decreases, current can flow reliably, which also helps to improve the gain of the output antenna 143. It should be noted that as long as the fixing member 144 has two or more electrical connection points, it can also be three.

[0054] In this example, the straight section 1431 further ensures that the arcuate portion 1432 of the output antenna 143 is sufficiently separated from the grounding conductor film 1402 and the shielding housing 150. While the grounding conductor film 1402 and the shielding housing 150 create electromagnetic wave shielding within their interior space, this also means that the grounding conductor film 1402 and the shielding housing 150 themselves are made of conductive resin material and are susceptible to electromagnetic interference. Therefore, in this example, the straight section 1431 is used to keep the arcuate portion 1432 of the output antenna 143 away from the grounding conductor film 1402. That is, a sufficient distance is ensured between the arcuate portion 1432 and the grounding conductor film 1402. This prevents the arcuate portion 1432 from being affected by electromagnetic interference from the grounding conductor film 1402 and the shielding housing 150.

[0055] In this example, the insect-proof net 160 is disposed inside the second housing 130 and outside the smoke detection space 132. The insect-proof net 160 prevents insects from entering the smoke detection space 132 and has a mesh size of approximately 0.5 mm. Furthermore, like the first housing 120 and the second housing 130, the insect-proof net 160 is made of a non-conductive resin material and is formed by bending a thin sheet-like net. Specifically, the net is bent into a cylindrical shape, and its end face is inserted into a retaining groove formed in the second housing. Thus, the insect-proof net 160 is held between the second housing 130 and the shielding housing 150, surrounding the smoke detection space 132.

[0056] Next, the operation of the smoke detector 100 in this example will be described. The smoke detector 100 in this example is installed in a high-fire-risk area of ​​the factory, namely the top plate 201 of the control box 200. The control unit 141 periodically energizes the light-emitting element 151, causing it to emit light. For example, at a timed interval of once every 10 seconds, the light-emitting element 151 is energized for approximately 20 milliseconds. This conserves power to the battery 121. Additionally, the light-receiving element 152 is also activated in conjunction with the timed activation of the light-emitting element 151. When no fire occurs, smoke does not flow into the smoke detection space 132, and the light from the light-emitting element 151 is not scattered. Furthermore, light from the outside is blocked by the maze wall 133. Therefore, the light-receiving element 152, which is activated at the predetermined time, does not detect light.

[0057] As described above, the light-emitting element 151 and the light-receiving element 152 periodically determine whether there is smoke. The control unit 141 also periodically sends information from the transmitting unit 142 when no fire has occurred. This periodically transmitted information includes a unique number assigned to each smoke detector 100, information indicating the remaining power of the battery 121, temperature information from a temperature sensor located in the CPU of the control unit 141, and signal information from the light-receiving element 152. When no fire has occurred, the signal from the light-receiving element 152 is below a predetermined threshold.

[0058] The control unit 141 transmits periodic information from the transmitting unit 142 to an external receiver. Specifically, it transmits signals from the output antenna 143 to a receiver configured on the production line. At this time, since the grounding conductor film 1402 and the shielding housing 150 of the substrate assembly 140 function as grounding elements, the antenna efficiency of the output antenna 143 can be improved. Furthermore, because the arcuate portion 1432 of the output antenna 143 is separated from the grounding conductor film 1402 by the straight portion 1431, electromagnetic coupling between the grounding conductor film 1402, the shielding housing 150, and the output antenna 143 is less likely to occur. This also improves the efficiency of the output antenna 143.

[0059] In the event of a fire, smoke rises in the control box 200. The rising smoke separates from the ceiling 201 by about 2 cm and flows along the ceiling 201. If a fan 203 is installed in the control box 200, the smoke is drawn towards the fan 203 along the ceiling 201. The smoke flows precisely through the opening of the inlet window 131 and into the smoke detection space 132. When the smoke detection space 132 is filled with smoke, light from the light-emitting element 151 illuminates the smoke and is scattered. This scattered light is detected by a light-receiving element 152, which is activated at the same time as the light-emitting element 151. The light-receiving element 152 outputs a weak but detectable detection signal of about a few nanoamps. This detection signal is amplified by the amplifier circuit 170 and then input to the control unit 141.

[0060] At this time, when electromagnetic waves are applied to the light receiving element 152 and the amplification circuit 170, electromagnetic noise may be generated, causing the smoke detector 100 to react incorrectly. However, in the smoke detector 100 of this example, the shielding space is formed by a shielding housing 150 made of conductive resin material and a grounding conductor film 1402. Moreover, the light receiving element 152 and the amplification circuit 170 are disposed within this shielding space. Therefore, the light receiving element 152 and the amplification circuit 170 are less susceptible to interference from electromagnetic waves.

[0061] When the signal from the light receiving element 152 exceeds a predetermined threshold, the control unit 141 determines that a fire has occurred and sends a notification signal from the transmitting unit 142. The notification LED 146 then flashes. However, to prevent the transmission of erroneous information, the notification signal can also be lengthy. For example, since the presence of smoke is periodically checked, a notification signal can be issued only after three or more consecutive signals exceeding the threshold are received. Alternatively, the notification signal can be determined in conjunction with a signal from a temperature sensor included in the CPU of the control unit 141.

[0062] Next, use Figure 13 and Figure 14 Other examples of the smoke sensor 100 in this example are described below. Figure 13 and Figure 2 Similarly, the smoke sensor 100 is shown in dissection. (As shown...) Figure 13 As shown, in other examples, the smoke detector 100 has an air guide section formed opposite to the inlet window 131. Specifically, in the inlet window 131, a first housing air guide section 124 is formed opposite to the first housing 120. In the inlet window 131, a shielding housing air guide section 155 is formed opposite to the shielding housing 150. Furthermore, in the inlet window 131, a second housing air guide section (maze wall 133) is formed opposite to the smoke detection space 132.

[0063] With the first housing 120 and the shielding housing 150 housed within the second housing 130, the first housing air guide 124, the shielding housing air guide 155, and the second housing air guide (maze wall 133) are continuous. Therefore, air enters from the inlet window 131, which extends approximately the entire axial length, and passes through the second housing air guide (maze wall 133), the shielding housing air guide 155, and the first housing air guide 124, from the location... Figure 13 The smoke detection space 132 on one end of the lower axial direction is smoothly guided to the position of the first housing 120 on the other end of the upper axial direction. In addition, the shield housing air guide 155 and the second housing air guide (maze wall 133) also function as a maze wall to prevent external light from the inlet window 131 from entering the smoke detection space 132.

[0064] In particular, such as Figure 14 As shown, the air guide portion 155 of the shielding housing also increases the surface area of ​​the outer surface of the shielding housing 150. The shielding housing 150 is formed of a conductive material and functions as a ground for the output antenna 143. Therefore, by increasing the outer surface area through the air guide portion 155 of the shielding housing, the function as a ground can be improved, and the output of the output antenna 143 can also be improved.

[0065] Next, regarding Figure 13 and Figure 14 The diagram illustrates the antenna performance of the smoke detector 100 as an example. Figure 15 This diagram illustrates the directivity of the output antenna 143, with the axis of the smoke detector 100 defined as the Z direction. The plane orthogonal to the Z-axis is the XY plane. Therefore, the planes containing the Z-axis are the ZX plane and the YZ plane, and the plane not containing the Z-axis is the XY plane. The horizontal polarization a is shown by the dashed line, and the vertical polarization b is shown by the solid line. As described above, the smoke detector 100 is mounted on the top plate 201 and side wall 202 of the control box 200, etc., via the base 110. Furthermore, the control box 200, etc., is typically formed of a metal plate. Therefore, with the smoke detector 100 mounted on the top plate 201 and side wall 202, the metal plate is located in the Z-axis direction.

[0066] Since the presence of the metal plate is believed to adversely affect the performance of the output antenna 143, the effect of the metal plate on the output antenna 143 was measured. Specifically, the antenna performance was measured on the ZX plane, YZ plane, and XY plane, respectively, with the metal plate not configured and with the metal plate configured to be 5.7 mm separated from the arc portion 1432 of the output antenna 143 in the Z-axis direction.

[0067] Figure 16The measurement results are shown. The radiation frequency of the output antenna 143 is set to 920 MHz. Although the performance of the output antenna 143 may be degraded in the ZX and YZ planes containing the axis Z, as Figure 16 As shown, its effect is limited. Although a decrease in output was observed in the 180-degree direction where the metal plate is located, almost no change was observed centered at 0 degrees in the opposite direction of the metal plate, from 0 degrees to 150 degrees and from 210 degrees to 360 degrees. The measurement results for the ZX plane are as follows: Without the metal plate, the maximum gain for horizontal polarization is -8.23 dBi, the average gain is -11.98 dBi, and the maximum gain for vertical polarization is -10.28 dBi, the average gain is -14.73 dBi. In contrast, with the metal plate, the maximum gain for horizontal polarization is -5.11 dBi, the average gain is -10.11 dBi, and the maximum gain for vertical polarization is -10.32 dBi, the average gain is -15.59 dBi.

[0068] The measurement results on the YZ plane are as follows: Without the metal plate, the maximum gain for horizontal polarization is -9.17 dBi, and the average gain is -12.96 dBi; for vertical polarization, the maximum gain is -10.36 dBi, and the average gain is -12.02 dBi. On the other hand, with the metal plate, the maximum gain for horizontal polarization is -4.96 dBi, and the average gain is -10.30 dBi; for vertical polarization, the maximum gain is -13.99 dBi, and the average gain is -20.01 dBi.

[0069] On the XY plane without the metal plate, the metal plate has a more limited impact on the performance of the output antenna 143. The effect of horizontal polarization is almost unobservable. Horizontal polarization also radiates across the entire 360 ​​degrees. The measurements on the XY plane are as follows: Without the metal plate, the maximum gain for horizontal polarization is -11.16 dBi, and the average gain is -13.93 dBi; for vertical polarization, the maximum gain is -7.97 dBi, and the average gain is -9.68 dBi. Moreover, with the metal plate, the maximum gain for horizontal polarization is -11.21 dBi, and the average gain is -15.33 dBi; for vertical polarization, the maximum gain is -9.14 dBi, and the average gain is -10.18 dBi.

[0070] When the device is positioned within the space of the control box 200, radio waves from the output antenna 143 radiate outwards through the gaps in the control box 200, the rubber seals, and the fan 203. Therefore, the presence of a metal plate along the Z-axis is unlikely to be a disadvantage. Instead, radio waves reflected by the metal plate radiate outwards through the aforementioned gaps, indicating that the efficiency of the output antenna 143 is improved.

[0071] It should be noted that since the smoke detector 100 in this example is configured in an enclosed space such as a control box 200, it does not have a speaker, but a speaker can also be used. If a speaker is included, the control unit 141 can also activate the speaker while the notification LED 146 flashes. This allows the fire to be announced to the surrounding area. Furthermore, to achieve a small and lightweight design, the smoke detector 100 in this example only has a signal transmitting unit 142 and does not have a receiving unit. However, it can have a receiving function. If the smoke detector 100 has a receiving function, it can also receive notification signals from other smoke detectors 100 configured nearby. In this case, when receiving notification signals from other smoke detectors 100, the speaker can be activated or the notification LED 146 can be flashed. Additionally, the receiving function can be used to receive signals from an externally configured management server. For example, signals that switch communication channels and frequency bands can be received, allowing changes to the settings of the smoke detector 100. In this case, the settings are changed via the control unit 141.

[0072] Furthermore, in the example described above, the control unit 141 determines that a fire has occurred and sends a notification signal when a fire is likely to occur. It is desirable that the notification signal can be detected near the signal from the light receiving element 152. However, the smoke detector 100 may always send a signal only at a predetermined time. In this case, the signals from each smoke detector 100 are received by receivers configured on the production line and sent to a management server configured at a different location from the production line via communication lines such as the Internet and / or a cloud system with an intranet. The management server then determines that a fire has occurred. If the notification signal is not detected by the smoke detector 100, it is not necessary to notify the LED 146.

[0073] Furthermore, in the above embodiments, an example of using the sensor of this disclosure as a smoke detector 100 in a factory was described. This is an example of a use requiring electromagnetic wave resistance, which is also the intended application of the sensor of this disclosure. However, the smoke detector 100 can also be used in other applications. It can be used not only in factories but also for environmental monitoring in remote areas. For example, it can also be used in substations, inside containers of ships or trucks, warehouses, and in boxes containing photovoltaic power generation batteries. Depending on the usage, the base 110 can be screwed to the ceiling of a building. In addition, depending on the usage, the base 110 is sometimes fixed to the wall of a building. Therefore, the function of the smoke detector 100 in this disclosure is not limited to use in factories, but also means that it can be widely used as a device for sensing smoke.

[0074] Furthermore, in the above embodiments, an example of using the sensor disclosed herein as a smoke sensor 100 was described. The smoke sensor 100 is an example of a sensor and represents a desired application. However, the detection element is not limited to the light-emitting element 151 and the light-receiving element 152. In addition, detection elements that sense odors, vibrations, sounds, etc., can also be used. For example, detection elements that detect carbon dioxide or odors can be used to detect the smell of burning grease in motors installed on the production line, thereby detecting abnormalities in the production line. Furthermore, when a motor installed on the production line malfunctions, it may vibrate violently or emit a loud abnormal noise. By detecting these vibrations or abnormal noises with a detection element, abnormalities in the production line can be detected in advance.

[0075] The sensor disclosed herein can be used as a wireless Internet of Things (IoT) sensor for a wide range of applications. In this case, it can also be used as a sensor in home appliances or wearable devices.

[0076] Furthermore, the size and material of the above embodiment are merely examples. Depending on the application of the sensor, the size and material of the shielding housing 150, etc., can be appropriately selected. For example, in the above example, the shielding housing 150 is formed by injection molding from a conductive resin material, but it can also be formed from a conductive metal material. Examples of metal materials include copper, aluminum, and iron. Alternatively, the shielding housing 150 can be formed from a non-conductive resin material, with a conductive metal plated or sprayed onto its surface. Therefore, the shielding housing 150 made of a conductive material only needs to be conductive; it can be made of either resin or metal. Additionally, the insect net 160 is also made of a non-conductive resin material in the above example, but it can also be constructed from non-conductive stainless steel wire.

[0077] (The public disclosure of technological ideas)

[0078] This specification discloses the ideas of several techniques described in the following list. Some items are sometimes described by alternatively referring to a multiple dependent form of an item preceding a subsequent item. Furthermore, some items are sometimes described by referring to a multiple dependent form of an item of another multiple dependent form. Items described in these multiple dependent forms define the ideas of several techniques.

[0079] (Technological Ideas 1)

[0080] A sensor, wherein the sensor comprises:

[0081] A first housing (120) made of non-conductive resin material is installed on the part to be detected;

[0082] A second housing (130) made of non-conductive resin material is mounted on the first housing;

[0083] A shielding housing (150) made of conductive material, disposed between the second housing and the first housing, is in the shape of a container with one open side, and holds the detection element inside the container shape; and

[0084] A substrate assembly (140) is disposed on one side of the shielding housing and holds an amplifier circuit (170), a control unit (141), a transmitter (142), and an output antenna (143). The amplifier circuit amplifies the signal detected by the detection element, the control unit controls the detection element, and the transmitter transmits the signal detected by the detection element to the outside.

[0085] The substrate assembly has a conductive grounding conductor film (1402) extending on one side of the shielding housing, the grounding conductor film being in communication with the shielding housing.

[0086] The amplification circuit is configured on the shielding housing side of the grounding conductor film.

[0087] The output antenna uses the grounding conductor film and the shielding housing as ground.

[0088] (Technological Ideas 2)

[0089] According to the sensor described in Technological Idea 1, the grounding conductor film of the substrate assembly and the shielding housing are electrically connected at two points by a fastener (144) made of conductive metal.

[0090] (Technological Ideas 3)

[0091] According to the sensor described in Technological Idea 1 or Technological Idea 2, the output antenna has an arcuate portion (1432) arranged in an arc shape along the inner periphery of the first housing, and a straight portion (1431) that moves the arcuate portion away from the grounding conductor film.

[0092] (Technological Ideas 4)

[0093] According to the sensor described in technology idea 1, wherein...

[0094] The sensor also has a base (110) fixed to the detected part.

[0095] The first housing is mounted on the base.

[0096] The second housing forms a smoke detection space (132) inside, allowing smoke to enter the smoke detection space and blocking external light.

[0097] The detection element has a light-emitting element (151) that projects light toward the smoke detection space, and a light-receiving element (152) that detects light projected from the light-emitting element and scattered in the smoke detection space.

[0098] The sensor functions as a smoke sensor (100).

[0099] (Technological Ideas 5)

[0100] According to the sensor described in Technique 4, the light-emitting element is held in a light-emitting element support (153) made of non-conductive resin material, which is electrically insulated from the grounding conductor film and the shielding shell.

[0101] (Technological Ideas 6)

[0102] According to the sensor described in Technique 4 or Technique 5, the light receiving element is held in a light receiving element support (154) made of a non-conductive resin material, electrically insulated from the grounding conductor film and the shielding housing.

[0103] (Technological Ideas 7)

[0104] According to any one of the technical ideas 4 to 6, a sensor is provided with an insect-proof net (160) made of non-conductive resin material inside the second housing and outside the smoke detection space, the insect-proof net preventing insects from entering the smoke detection space.

Claims

1. A perceptron, wherein, The sensor has the following features: A first housing made of non-conductive resin material is installed on the part being detected; A second housing made of non-conductive resin material is mounted on the first housing; A shielding housing made of conductive material is disposed between the second housing and the first housing, and is in the shape of a container with one open side, holding the detection element inside the container shape; as well as A substrate assembly is disposed on one side of the shielding housing and houses an amplification circuit, a control unit, a transmitting unit, and an output antenna. The amplification circuit amplifies the signal detected by the detection element, the control unit controls the detection element, and the transmitting unit transmits the signal detected by the detection element to the outside. The substrate assembly has a conductive grounding conductor film extending on one side of the shielding housing, the grounding conductor film being in communication with the shielding housing. The amplification circuit is configured on the shielding housing side of the grounding conductor film. The output antenna uses the grounding conductor film and the shielding housing as ground.

2. The sensor according to claim 1, wherein, The grounding conductor film of the substrate assembly is electrically connected to the shielding housing at two points via fasteners made of conductive metal.

3. The sensor according to claim 1, wherein, The output antenna has an arcuate portion arranged in an arc shape along the inner circumference of the first housing, and a straight portion that moves the arcuate portion away from the grounding conductor film.

4. The sensor according to claim 1, wherein, The sensor also has a base that is fixed to the part being detected. The first housing is mounted on the base. The second housing forms a smoke detection space inside, allowing smoke to enter and blocking external light. The detection element has a light-emitting element that projects light toward the smoke detection space, and a light-receiving element that detects light projected from the light-emitting element and scattered in the smoke detection space. The sensor functions as a smoke detector.

5. The sensor according to claim 4, wherein, The light-emitting element is held in a light-emitting element support made of non-conductive resin material and is electrically insulated from the grounding conductor film and the shielding shell.

6. The sensor according to claim 4, wherein, The light receiving element is held in a light receiving element support made of non-conductive resin material and is electrically insulated from the grounding conductor film and the shielding shell.

7. The sensor according to claim 4, wherein, Inside the second housing and outside the smoke detection space, an insect-proof net made of non-conductive resin material is disposed to prevent insects from entering the smoke detection space.

Images