Smoke sensor

Abstract

The objective is to obtain a smoke detector that can ensure smoke detection accuracy while simplifying the structural design compared to conventional smoke detectors. [Solution] The smoke detector according to this disclosure comprises a light-emitting element, a light-receiving element, and a control unit that determines whether or not smoke has been generated based on the amount of light received by the light-receiving element. It further comprises a first concave mirror that reflects light emitted from the light-emitting element and generates first reflected light. By providing the first concave mirror, it is possible to supply light with a desired amount of light and desired directionality to the smoke detection unit, thereby contributing to the realization of a smoke detector that can ensure smoke detection accuracy while simplifying structural design.

Description

Technical Field

[0001] The present disclosure relates to a smoke detector that optically senses smoke generated in a fire monitoring environment.

Background Art

[0002] There are various detectors installed in each warning area of a building, which is an example of a fire monitoring environment, that automatically detect the occurrence of a fire by using heat, combustion products (smoke), and flames generated by the fire and transmit a fire signal (see, for example, Non-Patent Document 1).

[0003] As one type of such a detector, there is a smoke detector that optically senses smoke generated in a fire monitoring environment by including a light-emitting element and a light-receiving element in a housing. A smoke detector installed in a house or the like introduces smoke generated in the fire monitoring environment into a smoke detection unit in the housing, and based on the amount of light that is scattered by smoke particles or the like in the smoke detection unit and enters the light-receiving element after the light emitted from the light-emitting element, there is one that adopts a scattering method for detecting the occurrence of smoke.

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When designing a conventional smoke detector using the scattering method, there are the following two problems. <The First Problem: Problem Regarding Complicating Stray Light Processing> In conventional smoke detectors using the scattering method, it is crucial to design the structure so that direct light from the light-emitting LED, or strong reflected light, does not enter the light-receiving element, while allowing a moderate amount of scattered light to enter.

[0006] Specifically, it is necessary to consider a structure that appropriately arranges the light-emitting and light-receiving elements and prevents stray light from entering the light-receiving elements. Consequently, there was a problem in that stray light processing became complicated and the structural design became complex.

[0007] <Second challenge: Issues related to securing a smoke detection area> In conventional smoke detectors using a scattering method, it is important to secure space for the smoke detection section to cause light scattering by smoke particles in order to improve smoke detection accuracy. When mounting LEDs as light-emitting elements on a substrate, if bullet-shaped LEDs are used, the leads can be extended during mounting, allowing for a smoke detection section with sufficient space along the substrate surface at the top of the substrate.

[0008] However, bullet-shaped LEDs are generally large and require considerable effort to mount. Therefore, if chip-type LEDs, which are smaller and easier to mount on circuit boards, can be used, the degree of freedom in structural design will increase. However, simply mounting chip-type LEDs on a circuit board makes it difficult to secure a smoke detection area with sufficient space along the surface of the circuit board at the top of the board.

[0009] This disclosure is made to solve the above-mentioned problems and aims to provide a smoke detector that can ensure smoke detection accuracy while simplifying structural design compared to conventional smoke detectors. [Means for solving the problem]

[0010] The smoke detector according to this disclosure comprises a light-emitting element, a light-receiving element, and a control unit that determines whether or not smoke has been generated based on the amount of light received by the light-receiving element, and further comprises a first concave mirror that reflects light emitted from the light-emitting element and generates first reflected light. [Effects of the Invention]

[0011] According to this disclosure, it is possible to obtain a smoke detector that can ensure smoke detection accuracy while simplifying the structural design compared to conventional smoke detectors. [Brief explanation of the drawing]

[0012] [Figure 1] This is a functional block diagram of a smoke detector according to Embodiment 1 of the present disclosure. [Figure 2] This is an explanatory diagram relating to the first concave mirror, which is a characteristic configuration of the smoke detector according to Embodiment 1 of the present disclosure. [Figure 3] This is an explanatory diagram relating to the second concave mirror, which is a characteristic configuration of the smoke detector according to Embodiment 1 of the present disclosure. [Figure 4] This is an overall configuration diagram of a smoke detector that combines the first feature shown in Figure 2 and the second feature shown in Figure 3 in Embodiment 1 of the present disclosure. [Modes for carrying out the invention]

[0013] Hereinafter, preferred embodiments of the smoke detector of this disclosure will be described with reference to the drawings. The smoke detector according to this disclosure is technically characterized by employing an optical system that includes a first concave mirror that reflects light emitted from a light-emitting element and generates a first reflected light. By having such a technical feature, it is possible to secure a smoke detection section with sufficient space even when using a chip LED as the light-emitting element.

[0014] Embodiment 1. FIG. 1 is a functional block diagram of a smoke detector 100 according to Embodiment 1 of the present disclosure. The smoke detector 100 according to Embodiment 1 includes a light emitting element 11, a first concave mirror 12, a light receiving element 21, a second concave mirror 22, and a control unit 30.

[0015] The smoke detector 100 shown in FIG. 1 shows a state in which the optical system is arranged in a positional relationship where the light from the light emitting element 11 can be received as reflected light by the light receiving element 21, rather than the scattering method described as the prior art. Hereinafter, FIG. 1 will be described with a configuration in which a dimming method is adopted to detect the occurrence of smoke by blocking light with smoke in the smoke detection unit and reducing the amount of received light.

[0016] The light emitting element 11 is an element that emits light used to determine whether smoke has occurred in the fire monitoring environment where the smoke detector 100 is installed.

[0017] The first concave mirror 12 reflects the light emitted from the light emitting element 11 and emits it as the first reflected light toward the smoke detection unit.

[0018] The second concave mirror 22 reflects the first reflected light that has passed through the smoke detection unit and emits it as the second reflected light toward the light receiving element 21.

[0019] The light receiving element 21 is an element that receives the second reflected light that has passed through the smoke detection unit.

[0020] The control unit 30 is a controller having a smoke detection function 31 that determines whether smoke has occurred based on the amount of the second reflected light received by the light receiving element 21 that has passed through the smoke detection unit. When the smoke detection function 31 of the control unit 30 adopts the dimming method, due to the presence of smoke particles in the smoke detection unit, the amount of received light decreases until it becomes below a preset threshold value, and it is determined that smoke has occurred in the fire monitoring environment, and a smoke detection signal is output.

[0021] Herein, the smoke detector 100 according to this embodiment 1 is characterized by having a first concave mirror 12 that generates first reflected light. First, the first characteristic of the optical system of the light-emitting part will be explained in detail with reference to Figure 2.

[0022] Figure 2 is an explanatory diagram relating to the first concave mirror 12, which is a characteristic configuration of the smoke detector 100 according to Embodiment 1 of this disclosure. Figure 2 shows the optical system of the light-emitting unit, which comprises a light-emitting element 11, the first concave mirror 12, and a cover 13 for the light-emitting element.

[0023] In Figure 2, the light-emitting element 11 is a chip LED that can be mounted on a substrate. The light-emitting element 11 mounted on the substrate emits light upwards. The light-emitting element 11 is covered by a light-emitting element cover 13.

[0024] The light-emitting element cover 13 has an opening 13a (pinhole) at an upper position opposite the light-emitting element 11. Light emitted from the light-emitting element 11 passes through the opening 13a without diffusing into the surroundings and is radiated to the outside of the light-emitting element cover 13, reaching the first concave mirror 12.

[0025] Furthermore, even if the light-emitting element 11 is a chip LED, the light source can be positioned at a higher location by providing an opening 13a at the upper part of the light-emitting element cover 13. In addition, by making the inner surface of the light-emitting element cover 13 mirrored, the light from the light-emitting element 11 can be emitted efficiently through the opening 13a.

[0026] Furthermore, by positioning the aperture 13a at the focal point of the first concave mirror 12, the light reflected by the first concave mirror 12 becomes parallel light. By making the light parallel, the light emitted from the light-emitting element 11 is efficiently directed towards the smoke detection section.

[0027] Note that a smaller diameter for the pinhole in aperture 13a will produce more parallel light, but considering the need to maintain light intensity, it is best to choose a size that is less than or equal to the diameter of the chip LED (or the diagonal if the chip LED is rectangular).

[0028] As described above, by designing and arranging the first concave mirror 12 and the light-emitting element cover 13, the light that reaches the first concave mirror 12 is reflected by the first concave mirror 12 as first reflected light, which is parallel light, and the first reflected light is emitted toward the smoke detection section.

[0029] By configuring the optical system of the light-emitting section as shown in Figure 2, it is possible to use a chip LED that can be mounted on a substrate as the light-emitting element 11, and to supply light with the desired light intensity and directionality toward the smoke detection section.

[0030] In other words, by using a light-emitting element cover 13 having an opening 13a, the spread of LED light can be suppressed and light from the light-emitting element 11 can be supplied to the first concave mirror 12, thereby reducing the complexity of stray light processing.

[0031] Furthermore, by using a configuration in which the first concave mirror 12 generates the first reflected light, even when a chip LED is used as the light-emitting element 11, it is possible to supply light with the desired amount of light and the desired directionality to the smoke detection section which has sufficient space, thereby ensuring the desired smoke detection accuracy.

[0032] It should be noted that using a light-emitting element cover 13 having an opening 13a is not a mandatory configuration. It is also possible to adopt a configuration in which the light emitted from the light-emitting element 11 is directly reflected by the first concave mirror 12 to generate the first reflected light without using a light-emitting element cover 13. In this case as well, it is possible to have design flexibility that simplifies the structural design while ensuring smoke detection accuracy.

[0033] Next, the features of the optical system of the light-receiving section will be described. The smoke detector 100 according to this embodiment 1 has a second feature: it is equipped with a second concave mirror 22 that generates a second reflected light. This second feature will be explained in detail with reference to Figure 3.

[0034] Figure 3 is an explanatory diagram relating to the second concave mirror 22, which is a characteristic configuration of the smoke detector 100 according to Embodiment 1 of this disclosure. Figure 3 shows the optical system of the light-receiving section, which comprises a light-receiving element 21, a second concave mirror 22, and a cover 23 for the light-receiving element.

[0035] Light that has passed through the smoke detection section and reached the second concave mirror 22 is reflected by the second concave mirror 22 as second reflected light, and the second reflected light is radiated toward the opening 23a provided at the top of the light-receiving element cover 23. The concave surface and arrangement of the second concave mirror 22 can be designed to focus the received parallel light toward the opening 23a.

[0036] In other words, the aperture 23a plays a role in restricting the light-receiving path in the light-receiving element 21 so that it receives the second reflected light generated by the second concave mirror 22 as incident light, and does not receive light that does not pass through the second concave mirror 22.

[0037] The light-receiving element cover 23 covers the light-receiving element 21 and has an opening 23a at an upper position facing the light-receiving element 21. The second reflected light reflected by the second concave mirror 22 is focused without diffusing into the surroundings, passes through the opening 23a, is taken into the interior of the light-receiving element cover 23, and reaches the light-receiving element 21.

[0038] Furthermore, by making the inner surface of the light-receiving element cover 23 mirrored, the light-receiving element 21 can receive more light incident from the opening 23a, thereby increasing the sensitivity of the sensor.

[0039] Furthermore, by positioning an aperture 23a at the focal point of the second concave mirror 22 and making the aperture 23a a pinhole, similar to the aperture 13a, only parallel light can be received, which also increases the sensitivity of the sensor.

[0040] In Figure 3, the light-receiving element 21 is a chip photodiode that can be mounted on a substrate. The light-receiving element 21 mounted on the substrate receives light that has passed through the smoke detection section, the second concave mirror, and the aperture 23a as second reflected light.

[0041] By configuring the optical system of the light-receiving section as shown in Figure 3, a chip photodiode that can be mounted on a substrate can be used as the light-receiving element 21, and it becomes possible to receive light with the desired amount of light and desired directionality that has passed through the smoke detection section, thereby suppressing the effects of stray light.

[0042] It should be noted that using a light-receiving element cover 23 having an opening 23a is not a mandatory configuration. It is also possible to adopt a configuration in which the second reflected light generated by the second concave mirror 22 is directly focused onto the light-receiving element 21 without using a light-receiving element cover 23. In this case as well, it is possible to have design flexibility that allows for easy structural design while ensuring smoke detection accuracy.

[0043] Next, we will describe a smoke detector configured by combining the first feature of the optical system of the light-emitting section shown in Figure 2 and the second feature of the optical system of the light-receiving section shown in Figure 3. Figure 4 is an overall configuration diagram of a smoke detector 100 in Embodiment 1 of this disclosure, which incorporates the first feature shown in Figure 2 and the second feature shown in Figure 3.

[0044] By combining the optical system of the light-emitting section having the first feature shown in Figure 2 with the optical system of the light-receiving section having the second feature shown in Figure 3, a smoke detector 100 employing a dimming method can be easily realized in which light with a desired amount of light and desired directionality passes through the smoke detection section and reaches the light-receiving element 21.

[0045] Generally, attenuation methods have less impact on detection sensitivity due to smoke particle size than scattering methods (smoke has different colors depending on its particle size, and in the scattering method using infrared light, the scattered light intensity of small black smoke particles decreases), and thus have higher smoke detection performance. However, in the attenuation method, if the distance between the light-emitting and light-receiving parts is short, the amount of light attenuation due to smoke decreases, so it is necessary to use a light-emitting part with high light output or to make the light-receiving part highly sensitive.

[0046] Therefore, by using the first concave mirror 12 and the second concave mirror 22, the effects of stray light can be suppressed, light with the desired amount and directionality can be supplied to the smoke detection section, and the light that has passed through the smoke detection section can be focused onto the light-receiving element 21, thereby realizing a compact configuration.

[0047] As a result, it is possible to realize a smoke detector that simplifies structural design while ensuring smoke detection accuracy compared to conventional smoke detectors.

[0048] Furthermore, the optical system of the light-emitting section having the first characteristic shown in Figure 2, or the optical system of the light-receiving section having the second characteristic shown in Figure 3, can be applied not only to the attenuation method but also to the scattering method.

[0049] In other words, the light-emitting unit having the configuration shown in Figure 2 can be used independently as a light-emitting unit for a scattering-type smoke detector. Similarly, the light-receiving unit having the configuration shown in Figure 3 can be used independently as a light-receiving unit for a scattering-type smoke detector.

[0050] Furthermore, by arranging the components so that the first reflected light reflected by the first concave mirror 12 does not directly enter the second concave mirror 22, but rather the first reflected light becomes scattered light due to the influence of smoke particles and enters the second concave mirror 22, it is possible to create a scattering-type smoke detector that applies both the light-emitting unit with the configuration of Figure 2 and the light-receiving unit with the configuration of Figure 3.

[0051] In either case, the first reflected light reflected by the first concave mirror 12 has high directivity and little stray light, eliminating the need for stray light treatment within the smoke detection section and simplifying the structure of the smoke detection section.

[0052] In other words, when using a light-emitting unit having the configuration shown in Figure 2 with the first feature, a compact optical system can supply light with the desired intensity and directionality to the smoke detection unit. Furthermore, when using a light-receiving unit having the configuration shown in Figure 3 with the second feature, a compact optical system can focus the light with the desired intensity that has passed through the smoke detection unit onto the light-receiving element.

[0053] Therefore, both optical systems shown in Figures 2 and 3 can contribute to the realization of smoke detectors that can ensure smoke detection accuracy while simplifying structural design compared to conventional smoke detectors.

[0054] Furthermore, these optical systems can be applied not only to smoke detectors employing the scattering method but also to smoke detectors employing the dimming method. In either case, they can contribute to the realization of smoke detectors that can ensure smoke detection accuracy while simplifying structural design.

[0055] Furthermore, when employing the scattering method, the control unit will determine that smoke has been generated if the amount of light received by the light-receiving element as scattered light exceeds a predetermined threshold for the scattering method.

[0056] On the other hand, when the dimming method is adopted, the control unit will determine that smoke has been generated if the amount of light received when light is directly incident on the light-receiving element falls below a predetermined threshold for the dimming method. [Explanation of symbols]

[0057] 11 Light-emitting element, 12 First concave mirror, 13 Cover for light-emitting element, 13a Aperture, 21 Light-receiving element, 22 Second concave mirror, 23 Cover for light-receiving element, 23a Aperture, 30 Control unit, 31 Smoke detection function, 100 Smoke detector.

Claims

1. Light-emitting element and Light-receiving element and A control unit that determines whether or not smoke has been generated based on the amount of light received by the light-receiving element. Equipped with, A first concave mirror that reflects light emitted from the light-emitting element and generates first reflected light. Features further equipped Smoke detector.

2. The light-emitting element, the light-receiving element, and the first concave mirror are arranged so that the light emitted from the light-emitting element and the first reflected light generated by the first concave mirror do not directly enter the light-receiving element. The control unit determines that smoke has been generated when the amount of light received by the light-receiving element when the first reflected light is incident on the light-receiving element as scattered light exceeds a first determination threshold. The smoke detector according to claim 1.

3. The light-emitting element is composed of a chip LED. A light-emitting element cover having an opening that allows the light emitted from the chip LED to pass through, and arranged so that the light passing through the opening reaches the first concave mirror. The smoke detector according to claim 2, further comprising:

4. The light-emitting element, the light-receiving element, and the first concave mirror are, The light emitted from the light-emitting element does not directly enter the light-receiving element, and The first reflected light generated by the first concave mirror is to be directly incident on the light-receiving element. Placed, The control unit determines that smoke has been generated when the amount of light received by the light-receiving element when the first reflected light is directly incident on the light-receiving element falls below a second determination threshold. The smoke detector according to claim 1.

5. A second concave mirror that reflects the first reflected light generated by the first concave mirror and generates a second reflected light that is reflected toward the light-receiving element. Furthermore, The light-emitting element, the light-receiving element, the first concave mirror, and the second concave mirror are, The light emitted from the light-emitting element does not directly enter the light-receiving element and the second concave mirror, The second reflected light generated by the second concave mirror is to be directly incident on the light-receiving element. They are arranged, The control unit determines that smoke has been generated when the amount of light received by the light-receiving element when the second reflected light is directly incident on the light-receiving element falls below a third determination threshold. The smoke detector according to claim 1.

6. The light-receiving element is composed of a chip photodiode, and the chip photodiode receives the second reflected light generated by the second concave mirror as incident light, and the light-receiving element cover is provided with an opening that restricts the light-receiving path so as not to receive light that does not pass through the second concave mirror. The smoke detector according to claim 5, further comprising:

7. The light-emitting element is composed of a chip LED. A light-emitting element cover having an opening that allows the light emitted from the chip LED to pass through, and arranged so that the light passing through the opening reaches the first concave mirror. A smoke detector according to any one of claims 4 to 6, further comprising:

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