JP2007309755A - Photoelectric smoke sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the effect of false report due to an indoor lamp or solar rays, while ensuring a smoke flow channel by simplifying a labyrinth shape, in a photoelectric smoke sensor. <P>SOLUTION: The photoelectric smoke sensor 1 is equipped with a light-emitting diode 2 for irradiating a monitor space S with light, a light-detecting element 3 for detecting the scattered light formed by the smoke particles in the monitor space S, an optical filter 5 for attenuating the light of a specific wavelength, a detection signal processing circuit 6 for determining the presence of smoke particles, on the basis of the light detection signal outputted from the light-detecting element 3 and a labyrinth 7 for preventing unwanted light from being detected by the light-detecting element 3. The optical filter 5 has characteristics for making the light in the vicinity of the wavelength of the light emitted from a light-emitting diode 2 transmitted and attenuating light with another wavelength and is arranged between a monitor space S and the light detection element 3. According to this constitution, the disturbance light resistance with respect to the indoor lamp or solar rays can be ensured, even if the shape of the labyrinth 7 is simplified. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a photoelectric smoke detector that detects smoke by light projection and reception.

  Conventionally, as this type of photoelectric smoke detector, for example, one having a configuration as shown in Patent Document 1 is known. This will be described with reference to FIGS. 9 (a), (b), (c) and FIG. The photoelectric smoke detector 90 includes a light emitting diode 91 that irradiates light to the monitoring space S, a light receiving element 92 that receives scattered light caused by smoke particles in the monitoring space S, and a light reception signal output from the light receiving element 92. A light reception signal processing circuit 93 that determines the presence or absence of smoke particles in the monitoring space S and a labyrinth 94 formed so as to surround the monitoring space S are provided.

  The light emitting diode 91, the light receiving element 92, and the light receiving signal processing circuit 93 are housed in the body 95, and the light emitting diode 91 irradiates the monitoring space S with light through the light projection opening 95 a of the body 95. 92 receives light from the monitoring space S through the light receiving opening 95 b of the body 95. In the monitoring space S, the light-projecting side prism lens 96 that reflects the light emitted from the light emitting diode 91 toward the center of the monitoring space S, and the light from the center of the monitoring space S is reflected toward the light receiving element 92. A light receiving side prism lens 97 is disposed. When smoke is present in the monitoring space S, a part of the light emitted from the light emitting diode 91 and reflected by the light projecting side prism lens 96 is scattered by the smoke, and a part of the scattered light is received by the light receiving side. The light is reflected by the prism lens 97 and received by the light receiving element 92.

  The labyrinth 94 has a first function for reducing the amount of light irradiated from the light emitting diode 91 that has passed through the smoke in the monitoring space S and incident on the light receiving element 92, and light outside the sensor 90. For example, a second function for reducing the amount of room light or sunlight incident on the light receiving element 92 and a third function for securing a smoke flow path so that smoke enters the monitoring space S from the outside of the sensor 90. Is responsible.

  The labyrinth 94 is formed by arranging a plurality of wall bodies 94a bent in a complicated manner or having complex irregularities formed on the surface so as to surround the monitoring space S, and in order to suppress the transmission and reflection of light, a black composite It is made of resin. The labyrinth 94 is covered with an insect net 98 and a protective cover 99, and the insect net 98 is provided with a large number of fine holes 98a in a lattice shape that enable the passage of smoke and the passage of insects and the like. The protective cover 99 is formed with a plurality of band-shaped holes 99a that allow smoke to flow.

The photoelectric smoke detector 90 having such a configuration emits light for smoke detection from the light emitting diode 91 to the monitoring space S, and based on the received light signal output from the light receiving element 92 at that time, the received light signal processing circuit. 93 detects smoke particles and measures the smoke concentration to determine whether or not a fire has occurred.
JP 2002-352346 A

  However, in the conventional photoelectric smoke sensor 90 as described above, the labyrinth 94 needs to have a complicated shape in order to realize the first function and the second function. It becomes difficult to secure the smoke flow path, which is a function. For this reason, in the conventional photoelectric smoke sensor 90, the smoke density in the outside of the sensor 90 and the monitoring space S is unlikely to be the same, and the smoke density in the monitoring space S is determined as the smoke density around the outside of the sensor 90. It may be judged that the smoke density is lower. This becomes more prominent as the velocity of airflow around the sensor 90 is slower. In addition, since the velocity of the airflow is slower as it is closer to the ceiling surface, if the sensor 90 is embedded in the ceiling and only the portion necessary for smoke detection is exposed from the ceiling surface, the inflow of smoke is reduced. In particular, the possibility that the smoke density in the monitoring space S is judged to be lower than the smoke density around the outside of the sensor 90 increases, and as a result, the detection of the fire may be delayed.

  On the contrary, if the shape of the labyrinth 94 is simplified, the smoke flow path, which is the third function, is secured and the inflow property of the smoke is improved. The smoke density matches, which makes it possible to more accurately determine the smoke density around the outside of the sensor 90 and to speed up fire detection. However, when the shape of the labyrinth 94 is simplified, the first function and the second function are reduced, and light such as light that has been emitted from the light emitting diode 91 and transmitted through the smoke in the monitoring space S, room light, sunlight, etc. Since external light is received by the light receiving element 92, a false alarm may occur.

  The present invention has been made to solve the above-described problems, and provides a photoelectric smoke detector that can reduce the influence of false alarms caused by ambient light while simplifying the shape of the labyrinth to ensure a smoke flow path. For the purpose.

  In order to achieve the above-mentioned object, the invention according to claim 1 receives the light projecting means for irradiating the monitoring space with light intermittently or modulated, and the scattered light generated when smoke particles are present in the monitoring space. In a photoelectric smoke detector, comprising: a light receiving means for detecting the presence of smoke particles in the monitoring space based on a light receiving signal output from the light receiving means; and a space between the monitoring space and the light receiving means. And an optical filter for attenuating light having a wavelength longer than that of the light emitted by the light projecting means.

  According to a second aspect of the present invention, in the photoelectric smoke detector according to the first aspect, an optical filter for attenuating light having a shorter wavelength than the light emitted by the light projecting means is provided between the monitoring space and the light receiving means. Is.

  A third aspect of the invention is the photoelectric smoke detector according to the first or second aspect, further comprising a filter circuit that cuts a direct current component and a low frequency alternating current component of the received light signal output from the light receiving means. It is.

  According to a fourth aspect of the present invention, in the photoelectric smoke detector according to the third aspect, a filter that cuts an AC component having a frequency higher than the frequency of the light emitted from the light projecting unit out of the received light signal output from the light receiving unit. A circuit is provided.

  According to a fifth aspect of the present invention, in the photoelectric smoke detector according to any one of the first to fourth aspects, the wavelength of the light receiving means is determined from the wavelength of the light emitted by the light projecting means between the monitoring space and the light receiving means. An optical filter for attenuating light up to the upper limit wavelength of the light receiving sensitivity is provided.

  According to a sixth aspect of the present invention, in the photoelectric smoke detector according to any one of the first to fifth aspects, the light projecting means is provided between the monitoring space and the light receiving means from the lower limit wavelength of the light receiving sensitivity of the light receiving means. The optical filter which attenuates the light to the wavelength of the light which irradiates is comprised.

  According to a seventh aspect of the present invention, in the photoelectric smoke detector according to any one of the first to sixth aspects, scattering occurring when smoke particles are present in the monitoring space between the monitoring space and the light receiving means. A lens for condensing light is arranged, and an optical filter is arranged between the lens and the light receiving means.

  According to an eighth aspect of the present invention, in the photoelectric smoke detector according to any one of the first to seventh aspects, the light projecting means and the light receiving means are housed in a housing, and the outside of the housing is a monitoring space. The light projecting means is arranged to irradiate light obliquely downward, and the light receiving means is arranged to receive light scattered obliquely upward from the monitoring space.

  According to the first aspect of the present invention, since light having a longer wavelength than the light emitted from the light projecting means is attenuated by the optical filter, the disturbance light resistance against disturbance light having a longer wavelength than the light emitted from the light projecting means. It is possible to simplify the shape of the labyrinth (or eliminate the labyrinth) and improve the inflow property of smoke into the monitoring space while securing the above.

  According to the second aspect of the present invention, since light having a shorter wavelength than the light emitted from the light projecting means is attenuated by the optical filter, in addition to disturbance light having a longer wavelength than the light emitted from the light projecting means, Simplify the shape of the labyrinth (or eliminate the labyrinth) and improve the inflow of smoke into the monitoring space while ensuring disturbance light resistance against disturbance light having a shorter wavelength than the light emitted from the light means. be able to.

  According to the invention of claim 3, since the direct current component and the low frequency alternating current component of the light receiving signal output from the light receiving means are cut by the filter circuit, the disturbance light resistance against the direct current component and the low frequency component disturbing light is improved. While ensuring, the shape of the labyrinth can be further simplified (or the labyrinth can be eliminated), and the inflow property of smoke into the monitoring space can be improved.

  According to the fourth aspect of the present invention, the AC component having a frequency higher than the frequency of the light emitted from the light projecting means is cut by the filter circuit in the light receiving signal output from the light receiving means. To improve the flow of smoke into the monitoring space by further simplifying the shape of the labyrinth (or eliminating the labyrinth) while ensuring the resistance to disturbance light with higher frequency components than the frequency of the light Can do.

  According to the invention of claim 5, the optical filter emits light from the light projecting means by attenuating light from the wavelength of light irradiated from the light projecting means to the upper limit wavelength of the light receiving sensitivity of the light receiving means. The number of optical thin films deposited on the optical filter can be reduced while ensuring disturbance light resistance against disturbance light having a wavelength longer than that of the light.

  According to the invention of claim 6, the optical filter is adapted to attenuate light from the lower limit wavelength of the light receiving sensitivity of the light receiving means to the wavelength of the light emitted from the light projecting means, so that the light is emitted from the light projecting means. The number of optical thin films deposited on the optical filter can be reduced while ensuring disturbance light resistance against disturbance light having a wavelength shorter than that of the light.

  According to the invention of claim 7, since the scattered light from the smoke in the monitoring space is collected by the light receiving lens and then received by the light receiving means through the optical filter, a larger amount of signal can be secured. it can.

  According to the invention of claim 8, since smoke outside the casing can be detected, smoke detection is possible without blocking the flow of smoke from any direction of 360 °. Furthermore, since smoke outside the casing can be detected, smoke detection can be performed even if a photoelectric smoke detector is embedded in the ceiling surface or wall surface.

Hereinafter, a photoelectric smoke detector according to an embodiment of the present invention will be described with reference to the drawings.
<First Embodiment>
First, the first embodiment will be described. 1A, 1B, 1C, and 2 show the configuration of the photoelectric smoke detector according to the first embodiment. The photoelectric smoke detector 1 is, for example, a device that is used by being mounted on an indoor ceiling surface, and detects smoke generated indoors by light projection and reception.

  The photoelectric smoke detector 1 includes a light emitting diode 2 that is a light projecting unit that irradiates the monitoring space S with light for detecting smoke, a light receiving element 3 that is a light receiving unit that receives scattered light generated by smoke particles, and a light. A light receiving lens 4 that collects light, an optical filter 5 that attenuates light of a specific wavelength, a light reception signal processing circuit 6 that determines the presence or absence of smoke particles based on a light reception signal output from the light receiving element 3, and unnecessary light Is provided with a labyrinth 7 for preventing the light receiving element 3 from receiving light, an insect net 8 for preventing insects and the like from entering the monitoring space S, and a housing 9 for storing and holding them. Yes.

  The housing 9 includes a light emitting diode 2, a light receiving element 3, a light receiving lens 4, an optical filter 6, and a body 10 that stores the light reception signal processing circuit 6, and a protective cover 11 that stores the labyrinth 7 and the insect net 8. Yes. The photoelectric smoke detector 1 is installed on the ceiling surface, for example, so that the body 10 is embedded in the ceiling surface and the protective cover 11 protrudes from the ceiling surface.

  The light emitting diode 2 is arranged in the body 10 so as to irradiate the monitoring space S obliquely downward through the projection opening 10a of the body 10, and the light receiving element 3 is scattered obliquely upward from the monitoring space S. It arrange | positions in the body 10 so that the light to light may be received through the light reception opening 10b of the body 10. FIG. The angle formed between the light emitting optical axis C1 of the light emitting diode 2 and the light receiving optical axis C2 of the light receiving element 3 is approximately 90 to 130 ° (preferably 100 to 110 °), and the light emitting optical axis C1 and the light receiving optical axis C2 are The plane constituted by is parallel to the vertical plane.

  The light receiving lens 4 is disposed between the monitoring space S and the light receiving element 3, and collects scattered light generated by smoke particles in the monitoring space S on the light receiving element 3. The optical filter 5 is disposed between the monitoring space S and the light receiving element 3 and between the lens 4 and the light receiving element 3, transmits light in the vicinity of the wavelength of the light emitted by the light emitting diode 2, and others. Attenuate light of a wavelength of.

  The light reception signal processing circuit 6 is a voltage conversion circuit that converts the light reception signal output from the light receiving element 3, an amplifier circuit, a low frequency cut filter circuit that cuts a direct current component and a low frequency alternating current component of the light reception signal, Among them, a high-frequency cut filter circuit that cuts AC components with a frequency higher than the frequency of light emitted from the light-emitting diode 2, and the presence or absence of smoke particles and measurement of smoke concentration are determined based on the received light signal to determine the occurrence of a fire. And a determination circuit for performing the operation.

  The labyrinth 7 has a light projecting side partition 71, a light projecting side trap 72, a light receiving side partition 73, and a light receiving side trap 74 for preventing unnecessary light from being received by the light receiving element 3. In order to suppress transmission and reflection of light, it is made of black synthetic resin. The light projecting side partition wall 71, the light projecting side trap section 72, the light receiving side partition section 73, and the light receiving side trap section 74 are integrally formed on an annular base body 75 and surround the monitoring space S. Is arranged.

  The light projecting partition wall 71 is composed of a single flat wall, and is disposed on the opposite side of the light emitting diode 2 with respect to the monitoring space S (the tip of the light emitting optical axis C1 of the light emitting diode 2). The wall surface of the body is inclined with respect to the light emission optical axis C1. The light projecting side trap portion 72 is composed of a plurality of plate-like wall bodies arranged in parallel with a gap, and an optical axis C3 formed by reflecting the light emitting optical axis C1 of the light emitting diode 2 by the light projecting side partition wall portion 71. The wall surface of each wall body is parallel to the optical axis C3. The light-receiving-side partition wall 73 is composed of a single flat wall, and is disposed on the opposite side of the light-receiving element 3 (the tip of the light-receiving optical axis C2 of the light-receiving element 3) with respect to the monitoring space S. Are inclined with respect to the light receiving optical axis C2. The light receiving side and the lap portion 74 are composed of a plurality of flat wall bodies arranged in parallel with a gap, and the light receiving optical axis C2 of the light receiving element 3 is reflected by the light receiving side partition wall 73 and has an optical axis C4. It is arrange | positioned previously and the wall surface of each wall body is parallel with respect to the optical axis C4.

  The labyrinth 7 having such a configuration has a first function for reducing the amount of smoke detection light that is irradiated from the light emitting diode 2 and transmitted through the smoke in the monitoring space S and enters the light receiving element 3, and the monitoring space S. A second function for reducing the amount of light, such as room light or sunlight, incident on the light receiving element 3, and a smoke flow path so that smoke enters the monitoring space S from the outside of the monitoring space S. It has a third function to ensure.

  The insect net 8 has a bottomed cylindrical shape and covers the outside of the labyrinth 7. In the insect repellent net 8, a large number of fine holes 8a are formed in a lattice shape that allows smoke to flow and prevents passage of insects and the like. The protective cover 11 has a bottomed cylindrical shape and covers the insect screen 8. The protective cover 11 is formed with a plurality of belt-like holes 11a that allow the smoke to flow.

  The photoelectric smoke detector 1 having such a configuration irradiates the monitoring space S with light for smoke detection from the light emitting diode 2, and based on the light reception signal (signal current) output from the light receiving element 3 at that time, The received light signal processing circuit 6 determines whether or not a fire has occurred. That is, the light emitting diode 2 modulates and emits smoke detection light intermittently, and the light receiving element 3 receives the light collected by the light receiving lens 4 and transmitted through the optical filter 5 and receives the light. A signal current corresponding to the amount is output. The light reception signal processing circuit 6 converts the signal current output from the light receiving element 3 by a voltage conversion circuit, amplifies it by an amplification circuit, and attenuates the direct current component and low frequency alternating current component of the signal by a low frequency cut filter circuit. At the same time, an AC component having a frequency higher than the light emission frequency (modulation frequency) of the diode 2 is attenuated by the high frequency cut filter circuit, and the presence / absence of smoke particles and the smoke concentration are measured from the signal. Determine if a fire has occurred. When it is determined that a fire has occurred, a warning is given by a buzzer (not shown).

  FIG. 3 shows the emission wavelength of the light emitting diode 2 and the transmission wavelength characteristic of the optical filter 5. The light emitting diode 2 has a light emission wavelength of approximately 880 to 1020 nm, and the light receiving element 3 has a light receiving sensitivity of approximately 700 to 1200 nm. The optical filter 5 transmits light in the vicinity of the light emission wavelength of the light emitting diode 2 (light having a wavelength of approximately 880 to 1020 nm), and light having a wavelength longer than the light irradiated by the light emitting diode 2 (light having a wavelength longer than 1020 nm). In addition, light having a characteristic of attenuating light having a shorter wavelength than light irradiated by the light emitting diode 2 (light having a wavelength shorter than 880 nm) is used.

  4A, 4B, and 4C show examples of the light emitting operation of the light emitting diode 2. FIG. For example, as shown in FIG. 4A, the light-emitting diode 2 intermittently irradiates light modulated at a light emission frequency of 5 k to 20 kHz so as to emit light for 50 to 200 μsec every 1 to 10 sec. In this case, the received light signal processing circuit 6 uses a low frequency cut filter circuit as a circuit that cuts a frequency component of approximately 0 to 200 Hz, and a high frequency cut filter circuit as a circuit that cuts a frequency component of approximately 30 k to 200 kHz.

  Further, for example, as shown in FIG. 4B, the light emitting diode 2 intermittently irradiates light modulated at an emission frequency of 100 k to 2 MHz so as to emit light for 0.5 to 10 μsec every 1 to 10 sec. For example, as shown in FIG. 4 (c), light modulated at a light emission frequency of 100 k to 2 MHz is intermittently irradiated so as to emit light for 0.5 to 10 μsec every 5 to 100 μsec. Also good. In these cases, the light reception signal processing circuit 6 does not need to include a high frequency cut filter circuit.

  According to the photoelectric smoke detector 1 of the present embodiment, when smoke is present in the monitoring space S, part of the smoke detection light emitted from the light emitting diode 2 is scattered by the smoke, and the scattering. After a part of the light is collected by the light receiving lens 4, it passes through the optical filter 5 and is received by the light receiving element 3.

  At this time, the smoke detection light that has passed through the smoke without being scattered by the smoke is reflected by the light projecting side partition 71 of the labyrinth 7 and enters the light projecting side trap 72 of the labyrinth 7. On the other hand, the light receiving element 3 views the light receiving side trap 74 by the light receiving side partition 73 of the labyrinth 7. Therefore, the amount of smoke detection light that has passed through the smoke is received by the light receiving element 3 is reduced. Similarly, the amount of smoke detection light emitted from the light emitting diode 2 when no smoke is present in the monitoring space S is also received by the light receiving element 3.

  In addition, external light such as room light and sunlight is blocked by the light receiving side partition 73 of the labyrinth 7 and is not directly received by the light receiving element 3. In addition, the external light that has entered the monitoring space S without being blocked by the light receiving side partition 73 is attenuated by being reflected a plurality of times inside the labyrinth 7 and is further reduced by the light-emitting diode 2 included in the external light. Since light other than near the emission wavelength is further attenuated by the optical filter 5, the amount of light received by the light receiving element 3 is greatly reduced.

  Further, the light in the vicinity of the light emission wavelength of the light emitting diode 2 included in the external light is not attenuated by the optical filter 5 but is reflected a plurality of times inside the labyrinth 7 so that the amplifier of the amplification circuit of the received light signal processing circuit 6 It is sufficiently attenuated to a level that does not saturate. For this reason, light in the vicinity of the light emission wavelength of the light emitting diode 2 included in the external light is received by the light receiving element 3 and output from the light receiving element 3 is sunlight, an incandescent lamp, a non-inverter fluorescent lamp, or the like. The external light component (the DC component of the received light signal and the low frequency AC component) is removed by the low frequency cut filter circuit of the received light signal processing circuit 6, and the external light component such as an inverter fluorescent lamp (the modulation of the light emitting diode 2 of the received light signal). The AC component having a frequency higher than the frequency is removed by the high frequency cut filter circuit of the received light signal processing circuit 6.

  Therefore, according to the photoelectric smoke detector 1 of the present embodiment, the labyrinth 7 is simply configured by the light emitting side partition wall portion 71, the light emitting side trap portion 72, the light receiving side partition portion 73, and the light receiving side trap portion 74. Even in the shape, the influence of outside light such as room light and sunlight can be greatly reduced, and scattered light from smoke particles in the monitoring space S can be detected with high accuracy. That is, the smoke inflow property and disturbance light resistance can be improved at the same time, and fire can be detected early while ensuring the disturbance light resistance.

  In the above embodiment, the light emitting wavelength of the light emitting diode 2 may be other than 880 to 1020 nm, and the light receiving sensitivity of the light receiving element 3 may be other than 700 to 1200 nm. In particular, when the light receiving sensitivity distribution of the light receiving element 3 is wide, the same effect can be obtained by changing the transmission characteristics of the optical filter 5.

  The optical filter 5 preferably has a characteristic of attenuating light from the wavelength of light emitted from the light emitting diode 2 to the upper limit wavelength of the light receiving sensitivity of the light receiving element 3 on the long wavelength side. With such a characteristic, it is possible to reduce the number of optical thin films deposited on the optical filter 5 while ensuring the disturbance light resistance against the incandescent lamp, and to reduce the cost. Furthermore, it is preferable that the optical filter 5 has a characteristic that attenuates light from the lower limit wavelength of the light receiving sensitivity of the light receiving element 3 to the wavelength of light irradiated by the light emitting diode 2 on the short wavelength side. With such characteristics, in addition to incandescent lamps, it is possible to reduce the number of optical thin films deposited on the optical filter 5 while ensuring resistance to external light against fluorescent lamps and sunlight, thereby reducing costs. .

  Furthermore, the labyrinth 7 has a first function for reducing the amount of smoke detection light that has passed through the smoke, incident on the light receiving element 3, a second function for reducing the amount of outside light incident on the light receiving element 3, and Any configuration and shape may be used as long as the third function for ensuring the inflow of smoke is not impaired. For example, the configuration may be such that the light-projecting side trap portion 72 is not provided.

  Further, the photoelectric smoke detector 1 may be configured not to include the light receiving lens 4. For example, the amount of light scattered from the smoke particles is improved by increasing the amount of light of the light emitting diode 2 or by increasing the angle formed by the light emitting optical axis C1 of the light emitting diode 2 and the light receiving optical axis C2 of the light receiving element 3. Thus, desired performance can be obtained without using the light receiving lens 3. Further, the photoelectric smoke detector 1 is not limited to the ceiling surface, and can be used by being attached to a wall surface or the like.

<Second Embodiment>
Next, a second embodiment will be described. FIGS. 5A and 5B show the configuration of a photoelectric smoke detector according to the second embodiment. The photoelectric smoke detector 1 of the present embodiment has a configuration that does not include the labyrinth 7, the insect net 8, and the protective cover 11 in the first embodiment. That is, the photoelectric smoke detector 1 of this embodiment uses the outside of the housing 9 as the monitoring space S. Further, the photoelectric smoke detector 1 of the present embodiment is different from the first embodiment in the transmission wavelength characteristic of the optical filter 5. Other configurations in the present embodiment are the same as those in the first embodiment.

  In the present embodiment, the light emitting diode 2 emits light obliquely downward to the monitoring space S outside the housing 9 through the light projection opening 10 a, and the light receiving element 3 is obliquely projected from the monitoring space S outside the housing 9. Light scattered upward is received through the light receiving opening 10b. The light emitting optical axis C1 of the light emitting diode 2 and the light receiving optical axis C2 of the light receiving element 3 are the same as those in the first embodiment. The light receiving lens 4 and the optical filter 5 are disposed between the monitoring space S and the light receiving element 3 as in the first embodiment. The photoelectric smoke detector 1 irradiates light for detecting smoke from the light emitting diode 2 to the monitoring space S outside the housing 9, and based on the light reception signal (signal current) output from the light receiving element 3 at that time. The light reception signal processing circuit 6 determines whether or not a fire has occurred.

  FIG. 6 shows the emission wavelength of the light emitting diode 2 and the transmission wavelength characteristic of the optical filter 5 in the present embodiment. As in the first embodiment, the light emitting diode 2 has a light emission wavelength of approximately 880 to 1020 nm, and the light receiving element 3 also has a light receiving sensitivity of approximately 700 to 1200 nm as in the first embodiment. Use what has. Unlike the first embodiment, the optical filter 5 transmits light having a half-value width of about ± 30 nm (910 nm to 980 nm) around the peak value of the emission wavelength of the light emitting diode 2 and light of other wavelengths. And a transmissive wavelength range is made narrower than that of the first embodiment.

  According to the photoelectric smoke detector 1 of the present embodiment, when smoke is present in the monitoring space S, a part of the smoke detection light emitted from the light emitting diode 2 is emitted as in the first embodiment. Is scattered by smoke, and a part of the scattered light is collected by the light receiving lens 4 and then transmitted through the optical filter 5 and received by the light receiving element 3.

  At this time, the smoke detection light that has passed through the smoke without being scattered by the smoke travels straight toward the far side without hitting any structure. Therefore, the light for smoke detection that has passed through the smoke is not received by the light receiving element 3. Similarly, the light for detecting smoke emitted from the light emitting diode 2 when no smoke is present in the monitoring space S is not received by the light receiving element 3.

  In addition, outside light such as room light and sunlight is light outside the vicinity of the light emission wavelength of the light emitting diode 2 included in the external light (outside the peak value of the light emission wavelength of the light emitting diode 2 is ± 30 nm outside the half width). Is attenuated by the optical filter 5, the amount of light received by the light receiving element 3 is greatly reduced.

  Furthermore, light in the vicinity of the light emission wavelength of the light emitting diode 2 included in the external light (within a half value width of ± 30 nm centering around the peak value of the light emission wavelength of the light emitting diode 2) is not attenuated by the optical filter 5, but the external light The light reception signal output from the light receiving element 3 when the light near the light emission wavelength of the light emitting diode 2 included in the light receiving element 3 is received by the light receiving element 3 is the same as in the first embodiment. An external light component such as an inverter fluorescent lamp is removed by a low frequency cut filter circuit of the light reception signal processing circuit 6, and an external light component such as an inverter fluorescent lamp is removed by a high frequency cut filter circuit of the light reception signal processing circuit 6.

  Therefore, according to the photoelectric smoke detector 1 of the present embodiment, the influence of outside light such as room light and sunlight can be greatly reduced even in the configuration without the labyrinth 7 of the first embodiment. It is possible to detect the scattered light from the smoke particles in the monitoring space S with high accuracy. That is, the smoke inflow property and disturbance light resistance can be improved at the same time, and fire can be detected early while ensuring the disturbance light resistance.

  Moreover, because the outside of the housing 9 is the monitoring space S, smoke detection is possible without blocking the flow of smoke from any direction of 360 °. Accordingly, it is possible to detect fire early without depending on the direction of smoke flow, and it is possible to measure the true smoke concentration. Further, since the outside of the housing 9 is the monitoring space S, it is possible to detect smoke even if the photoelectric smoke detector 1 is installed so as to be completely flat with the ceiling surface or the wall surface. The protrusion from the ceiling surface and wall surface of the vessel 1 can be eliminated, the interior design is not impaired, and the smoke concentration in the vicinity of the ceiling surface and wall surface, which could not be measured conventionally, can be measured.

  In the above embodiment, the transmission wavelength characteristic of the optical filter 5 is not limited to the characteristic of transmitting light having a half-value width of about ± 30 nm around the peak value of the emission wavelength of the light-emitting diode 2, and the photoelectric smoke detector 1 What is necessary is just to change a half value width according to the kind and intensity | strength of external light in the environment which uses.

<Third Embodiment>
Next, a third embodiment will be described. 7A and 7B show the configuration of a photoelectric smoke detector according to the seventh embodiment. The photoelectric smoke detector 1 of this embodiment is different from the second embodiment in the direction of the light receiving optical axis C2 of the light receiving element 3. Other configurations in the present embodiment are the same as those in the second embodiment.

  In the present embodiment, the light emitting diode 2 irradiates light obliquely downward to the monitoring space S outside the housing 9 through the light projection opening 10a, as in the second embodiment. Unlike the second embodiment, the light receiving element 3 receives light scattered in the substantially horizontal direction from the monitoring space S outside the housing 9 through the light receiving opening 10b. That is, the light receiving element 3 is disposed in the protruding portion 10c of the body 10 (housing 9), and the light receiving optical axis C2 is substantially parallel to the ceiling surface. The angle formed between the light emitting optical axis C1 of the light emitting diode 2 and the light receiving optical axis C2 of the light receiving element 3 is approximately 90 to 130 ° (preferably 100 to 110 °), and the light emitting optical axis C1 and the light receiving optical axis C2 are The plane constituted by is parallel to the vertical plane.

  The light receiving lens 4 and the optical filter 5 are disposed in the protruding portion 10 c of the body 10 (housing 9) together with the light receiving element 3. The light receiving lens 4 is disposed between the monitoring space S and the light receiving element 3, and the optical filter 5 is disposed between the monitoring space S and the light receiving element 3 and between the lens 4 and the light receiving element 3. Has been. As in the second embodiment, the photoelectric smoke detector 1 irradiates the monitoring space S outside the housing 9 with light for detecting smoke from the light emitting diode 2 and outputs the light from the light receiving element 3 at that time. Based on the received light signal (signal current), the received light signal processing circuit 6 determines whether or not a fire has occurred.

  According to the photoelectric smoke detector 1 of the present embodiment, smoke inflow property and disturbance light resistance can be improved at the same time as in the second embodiment, and fire resistance can be ensured while ensuring disturbance light resistance. Early detection is possible. Also, smoke detection is possible even if the photoelectric smoke detector 1 is installed so that only the protruding portion 10c of the body 10 (housing 9) protrudes from the ceiling surface or wall surface. The protrusion from the ceiling surface or wall surface can be reduced, the interior design is not impaired, and the smoke density in the vicinity of the ceiling surface or wall surface that cannot be measured conventionally can be measured.

  Further, since the light receiving optical axis C2 of the light receiving element 3 is substantially parallel to the ceiling surface, light from the vicinity of the floor surface, for example, signal light or sunlight from the remote control reflected or scattered by the floor surface is received by the light receiving element 3. Therefore, the malfunction of the photoelectric smoke detector 1 can be reduced.

  In the above embodiment, for example, as shown in FIGS. 8A and 8B, on the light receiving optical axis C2 of the light receiving element 3 and at a position opposite to the light receiving element 3 with respect to the monitoring space S, A field limiting body 15 that limits the light receiving field of the light receiving element 3 may be provided. According to such a configuration, it becomes possible to further reduce malfunctions caused by light reflected or scattered from the floor surface, for example, light from the vicinity of the floor surface, such as signal light from the remote controller or sunlight.

(A) is a perspective view of the photoelectric smoke detector which concerns on the 1st Embodiment of this invention, (b) is the sectional drawing, (c) is the sectional view on the AA line of (b). The disassembled perspective view of the photoelectric smoke detector. The figure which shows the light emission wavelength of the light emitting diode of the photoelectric smoke sensor, and the transmission wavelength characteristic of an optical filter. (A) is a figure which shows the light emission operation example of the light emitting diode of the photoelectric smoke detector, (b) is a figure which shows another light emission operation example of the light emitting diode, (c) is another light emission of the light emitting diode. The figure which shows an operation example. (A) is a perspective view of the photoelectric smoke detector which concerns on the 2nd Embodiment of this invention, (b) is the sectional drawing. The figure which shows the light emission wavelength of the light emitting diode of the photoelectric smoke sensor, and the transmission wavelength characteristic of an optical filter. (A) is a perspective view of the photoelectric smoke detector which concerns on the 3rd Embodiment of this invention, (b) is the sectional drawing. (A) is a perspective view which shows another structure of the photoelectric smoke detector, (b) is the sectional drawing. (A) is a perspective view of a conventional photoelectric smoke detector, (b) is a sectional view thereof, and (c) is a sectional view taken along line BB of (b). The exploded perspective view of the conventional photoelectric smoke detector.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoelectric smoke detector 2 Light emitting diode 3 Light receiving element 4 Light receiving lens 5 Optical filter 6 Light receiving signal processing circuit 7 Labyrinth 8 Insect net 9 Case 10 Body 10a Light emitting opening 10b Light receiving opening 10c Protruding part 11 Protective cover 15 Field of view Limiting body 71 Light-emitting side partition wall 72 Light-emitting side trap part 73 Light-receiving side partition part 74 Light-receiving side trap part 75 Base part S Monitoring space

Claims (8)

Light projecting means for irradiating the monitoring space with light intermittently or modulated, light receiving means for receiving scattered light generated when smoke particles are present in the monitoring space, and light reception output from the light receiving means In a photoelectric smoke detector comprising light receiving signal processing means for determining the presence or absence of smoke particles in the monitoring space based on a signal,
A photoelectric smoke detector comprising an optical filter for attenuating light having a longer wavelength than the light emitted by the light projecting means between the monitoring space and the light receiving means.   2. The photoelectric smoke detector according to claim 1, further comprising an optical filter for attenuating light having a shorter wavelength than the light emitted by the light projecting unit between the monitoring space and the light receiving unit.   The photoelectric smoke sensor according to claim 1 or 2, further comprising a filter circuit that cuts a direct current component and a low frequency alternating current component of the light reception signal output from the light receiving means.   4. The photoelectric smoke according to claim 3, further comprising a filter circuit that cuts an AC component having a frequency higher than a frequency of light emitted from the light projecting unit out of a light reception signal output from the light receiving unit. sensor.   The optical filter for attenuating light from the wavelength of light emitted by the light projecting means to the upper limit wavelength of the light receiving sensitivity of the light receiving means is provided between the monitoring space and the light receiving means. The photoelectric smoke detector according to any one of claims 1 to 4.   The optical filter for attenuating light from a lower limit wavelength of light receiving sensitivity of the light receiving means to a wavelength of light emitted by the light projecting means is provided between the monitoring space and the light receiving means. The photoelectric smoke detector according to any one of claims 1 to 5. Between the monitoring space and the light receiving means, a lens for collecting scattered light generated when smoke particles exist in the monitoring space,
The photoelectric smoke detector according to any one of claims 1 to 6, wherein the optical filter is disposed between the lens and the light receiving means. The light projecting means and the light receiving means are housed in a housing, and the outside of the housing is the monitoring space.
The light projecting means is arranged to irradiate light obliquely downward,
8. The photoelectric smoke detector according to claim 1, wherein the light receiving means is disposed so as to receive light scattered obliquely upward from the monitoring space.

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