Smoke detector

Abstract

To provide means for determining a degree of contamination in a container concerning a smoke detector of a two-light receiving system.SOLUTION: A smoke detector 1 of a two-light receiving system includes: a first light emitting section 11 for emitting polarized light; a first light receiving section 12 having a first light receiving axis (arrow C) to cross with a light emitting axis (arrow B) of the first light emitting section 11; a second light receiving section 13 having a second light receiving axis (arrow D) to cross with the light emitting axis (arrow B) of the first light emitting section 11; and a second light emitting section 14 for emitting unpolarized light. The first light receiving section 12 is arranged on a first electronic circuit board 15, and the second light receiving section 13 is arranged on a second electronic circuit board 16 so as to orthogonally cross the first electronic circuit board 15. The second light emitting section 14 is arranged on the first electronic circuit board 15. A contamination determination section (not shown in Fig). determines a degree of contamination in a container 17 based on a signal generated by at least one of the first light receiving section 12 and the second light receiving section 13 during light emission by the second light emitting section 14.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a device for detecting smoke. [Background technology]

[0002] There are smoke detection devices that detect the occurrence of smoke in a monitored space by detecting smoke contained in the monitored space. One type of smoke detection device is called a photoelectric type. Photoelectric smoke detection devices detect smoke based on a signal generated when the light receiving unit receives light that is emitted from the light emitting unit and reflected by smoke particles in the air that flows from the outside into a container that houses the light emitting unit and the light receiving unit.

[0003] Another type of photoelectric smoke detector is the dual-light-receiving type. Dual-light-receiving smoke detectors emit polarized light in the direction of the light-emitting axis from the light-emitting element, and determine the type of smoke in the air based on the signals generated by the two light-receiving elements, which have light-receiving axes that intersect the light-emitting axis from different directions.

[0004] Patent Document 1, for example, is a patent document disclosing a two-light receiving smoke detector. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-203889 Summary of the Invention [Problem to be solved by the invention]

[0006] Photoelectric smoke detectors detect smoke particles in the air that flows from a monitored space into a container that forms a space for detecting smoke. The air that flows into the container contains dust particles, and some of this dust particles adhere to the inside of the container as dirt. Some of this dirt adheres to the light-emitting or light-receiving element, blocking or reflecting part of the light emitted from the light-emitting element. In addition, some of the dirt adheres to the inner walls of the container or structures within the container, further reflecting the light emitted from the light-emitting element and reflected by particles in the air. As a result, the accuracy of smoke detection by the smoke detector decreases.

[0007] If the degree of contamination inside the housing of a photoelectric smoke detector can be determined, it will be possible to reduce false detections of smoke caused by contamination by cleaning or replacing the housing before the smoke detection accuracy exceeds the acceptable range. Therefore, there is a need to be able to determine the degree of contamination inside the housing of a photoelectric smoke detector. There is a similar need for dual-receiver smoke detectors, which are a type of photoelectric detector.

[0008] In view of the above circumstances, an object of the present invention is to provide a means for determining the degree of contamination inside a container in a dual-light receiving smoke detector. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention proposes a smoke detection device comprising: a first light-emitting unit that emits polarized light; a first light-receiving unit that has a first light-receiving axis that intersects with the light-emitting axis of the first light-emitting unit; a second light-receiving unit that has a second light-receiving axis that intersects with the light-emitting axis of the first light-emitting unit and is in a direction different from the first light-receiving axis; a smoke determination unit that determines the type of smoke in the air based on a signal generated by the first light-receiving unit while the first light-emitting unit is emitting light and a signal generated by the second light-receiving unit while the first light-emitting unit is emitting light; and a second light-emitting unit that emits non-polarized light and a contamination determination unit that determines the degree of contamination inside a container that forms a space for detecting smoke based on at least one of the signal generated by the first light-receiving unit while the second light-emitting unit is emitting light and the signal generated by the second light-receiving unit while the second light-emitting unit is emitting light. [Effects of the Invention]

[0010] According to the smoke detection device of the present invention, the degree of contamination inside the container is determined by the light emitted by the second light-emitting unit, so the degree of contamination inside the container can be determined with higher accuracy than with a smoke detection device that does not have a second light-emitting unit. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram schematically illustrating the configuration of a smoke detection device according to an embodiment. [Figure 2] FIG. 10 is a diagram schematically illustrating the configuration of a smoke detection device according to a modified example. [Figure 3] FIG. 10 is a diagram schematically illustrating the configuration of a smoke detection device according to a modified example. [Figure 4] FIG. 10 is a diagram schematically illustrating the configuration of a smoke detection device according to a modified example.

[0012] [Embodiment] A smoke detection device 1 according to one embodiment of the present invention will be described below. The smoke detection device 1 is a dual-light receiving smoke detection device. FIG. 1 is a diagram schematically illustrating the configuration of the smoke detection device 1. However, in FIG. 1, components that are not related to the features of the present invention are omitted. FIG. 1(A) is a plan view of the smoke detection device 1 with the lid of the container removed. FIG. 1(B) is a view of the cross section indicated by the dashed line in FIG. 1(A) as viewed in the direction of arrow A.

[0013] In the following description, for convenience, the direction in which the paper on which FIG. 1(A) is drawn extends is taken as the horizontal plane.

[0014] The smoke detection device 1 includes a first light-emitting unit 11, a first light-receiving unit 12, a second light-receiving unit 13, a second light-emitting unit 14, a first electronic circuit board 15, a second electronic circuit board 16, a container 17, and a light-shielding member 18. The smoke detection device 1 also includes a smoke determination unit (not shown) and a contamination determination unit (not shown).

[0015] The first light-emitting section 11 emits polarized light in the direction of the light-emitting axis indicated by the arrow B in FIG.

[0016] The first light receiving unit 12 is disposed on the first electronic circuit board 15. The first light receiving unit 12 receives light directed in the direction of a first light receiving axis indicated by arrow C in FIG. 1(B) and generates a signal indicating the intensity of the received light. The first light receiving axis is an axis that intersects with the light emitting axis of the first light emitting unit 11 at a predetermined angle within a vertical plane (a plane perpendicular to the horizontal plane) that includes the light emitting axis of the first light emitting unit 11.

[0017] The second light receiving unit 13 is disposed on the second electronic circuit board 16. The second light receiving unit 13 receives light directed in the direction of a second light receiving axis indicated by arrow D in Figure 1(A) and generates a signal indicating the intensity of the received light. The second light receiving axis is an axis that intersects with the light emitting axis of the first light emitting unit 11 at a predetermined angle within a horizontal plane including the light emitting axis of the first light emitting unit 11.

[0018] The angle between the light-emitting axis of the first light-emitting unit 11 and the first light-receiving axis of the first light-receiving unit 12 may be the same as or different from the angle between the light-emitting axis of the first light-emitting unit 11 and the second light-receiving axis of the second light-receiving unit 13.

[0019] The second light-emitting unit 14 is disposed on the first electronic circuit board 15. The second light-emitting unit 14 emits unpolarized light for determining the degree of contamination inside the container 17. The light emitted by the second light-emitting unit 14 is directed toward a wide area within the container 17, including the smoke detection area.

[0020] The smoke detection unit (not shown) determines the presence or absence of smoke based on the intensity of a signal generated by, for example, the first light-receiving unit 12 during a period when the first light-emitting unit 11 is emitting light and the second light-emitting unit 14 is not emitting light. The smoke detection unit also determines the type of smoke based on the signal generated by the first light-receiving unit 12 and the signal generated by the second light-receiving unit 13 during a period when the first light-emitting unit 11 is emitting light and the second light-emitting unit 14 is not emitting light.

[0021] The contamination determination unit (not shown) determines the degree of contamination inside the container 17 based on at least one of the signals generated by the first light-receiving unit 12 and the second light-receiving unit 13 during a period when the first light-emitting unit 11 is not emitting light and the second light-emitting unit 14 is emitting light. For example, the contamination determination unit makes the following determination.

[0022] When the intensity of the signal generated by the first light receiving unit 12 falls below the lower limit threshold, it is determined that the degree of contamination of the first light receiving unit 12 has exceeded the allowable range. When the intensity of the signal generated by the first light receiving unit 12 exceeds the upper limit threshold, it is determined that the degree of contamination of the structure, such as a wall surface facing the first light receiving unit 12, has exceeded the allowable range. When the intensity of the signal generated by the second light receiving unit 13 falls below the lower limit threshold, it is determined that the degree of contamination of the second light receiving unit 13 has exceeded the allowable range. When the intensity of the signal generated by the second light receiving unit 13 exceeds the upper limit threshold, it is determined that the degree of contamination of the structure, such as a wall surface facing the second light receiving unit 13, has exceeded the allowable range.

[0023] The above-described method of determination by the contamination determination unit is merely an example, and other methods may be employed. For example, the contamination determination unit may determine the degree of contamination inside the container 17 based on the ratio between the signal generated by the first light receiving unit 12 and the signal generated by the second light receiving unit 13.

[0024] It is important to note here that the second light-emitting unit 14 is disposed on the first electronic circuit board 15, which is different from the second electronic circuit board 16 on which the second light-receiving unit 13 is disposed. When the second light-emitting unit 14 is disposed on the first electronic circuit board 15, the light emitted from the second light-emitting unit 14 strikes the second electronic circuit board 16 at a deeper angle (close to perpendicular) than when the second light-emitting unit 14 is disposed on the second electronic circuit board 16. Therefore, the light emitted from the second light-emitting unit 14 and reflected by dirt adhering to the second electronic circuit board 16 is more likely to reach the first light-receiving unit 12. As a result, the degree of contamination of the second electronic circuit board 16 can be determined with high accuracy.

[0025] The light-shielding member 18 is a cylindrical light-shielding member arranged to surround the first light-receiving unit 12. The upper bottom surface of the light-shielding member 18 is open so that light traveling along the first light-receiving axis (arrow C in FIG. 1(B)) can reach the first light-receiving unit 12. The light-shielding member 18 blocks light traveling along the first light-receiving axis and toward the first light-receiving unit 12 in a direction intersecting the first light-receiving axis. The light blocked by the light-shielding member 18 includes light emitted from the first light-emitting unit 11 and traveling away from the light-emitting axis of the first light-emitting unit 11 toward the first light-receiving unit 12, and light emitted from the first light-emitting unit 11 and reflected inside the container 17 toward the first light-receiving unit 12. The light-shielding member 18 serves to reduce the effect of these lights on determining the presence or absence of smoke and the type of smoke.

[0026] The second light-emitting unit 14 is disposed at a position where the light traveling directly from the second light-emitting unit 14 to the first light-receiving unit 12 is blocked by the light-blocking member 18. Therefore, compared to when the light emitted by the second light-emitting unit 14 directly reaches the first light-receiving unit 12, the amplitude of the signal generated by the first light-receiving unit 12 when determining whether contamination is present is smaller overall, and the amount of change in amplitude when contamination is present compared to the normal amplitude becomes more pronounced. This makes it easier for the contamination determination unit to determine the degree of contamination.

[0027] Container 17 is a component that forms a space for detecting smoke, and houses first light-emitting unit 11, first light-receiving unit 12, second light-receiving unit 13, etc. Container 17 is provided with an inlet that serves as a passageway for air to flow into the interior from the space to be monitored, and an outlet that serves as a passageway for the air that has flowed into the interior to flow out to the outside.

[0028] In addition to the components shown in Figure 1, the smoke detection device 1 may also include, for example, a fan that forcibly generates a flow of air from the outside into the container 17, and a filter that removes dust particles larger than the size of smoke particles from the air flowing into the container 17.

[0029] In addition, the results of smoke detection and the determination of the type of smoke by the smoke determination unit, and the results of determination of the degree of contamination inside the container 17 by the contamination determination unit may be notified to maintenance personnel, etc. by a display unit (not shown in Figure 1) provided in the smoke detection device 1 or a sound by a sound unit (not shown in Figure 1), or may be notified to an equipment manager, etc. via a higher-level system, such as a fire receiving panel, by a communication unit (not shown in Figure 1) provided in the smoke detection device 1.

[0030] According to the above-described smoke detection device 1, the degree of contamination inside the container 17 can be determined, so that facility managers and the like can take measures such as cleaning or replacing the smoke detection device 1 before the accuracy of smoke detection and smoke type determination drops below the acceptable level due to contamination inside the container 17.

[0031] [Variations] The above-described embodiment is a specific example of the present invention, and various modifications are possible within the scope of the technical concept of the present invention. Examples of such modifications are shown below. Note that two or more of the following modifications may be combined as appropriate.

[0032] (Variation 1) In the above-described embodiment, the first light receiving unit 12 is arranged on the first electronic circuit board 15, but the first light receiving unit 12 does not have to be arranged on the first electronic circuit board 15. In other words, as long as the first light receiving unit 12 is arranged so that the light receiving axis of the first light receiving unit 12 becomes the first light receiving axis (arrow C in FIG. 1B) that intersects with the light emitting axis of the first light emitting unit 11 (arrow B in FIG. 1B), the first light receiving unit 12 may be arranged on any member.

[0033] Furthermore, in the above-described embodiment, the second light receiving unit 13 is arranged on the second electronic circuit board 16, but the second light receiving unit 13 does not have to be arranged on the second electronic circuit board 16. In other words, as long as the second light receiving unit 13 is arranged so that the light receiving axis of the second light receiving unit 13 intersects with the light emitting axis (arrow B in FIG. 1) of the first light emitting unit 11 and forms a second light receiving axis (arrow D in FIG. 1A) in a direction different from the first light receiving axis (arrow C in FIG. 1B), the second light receiving unit 13 may be arranged on any member.

[0034] (Variation 2) The smoke detection device 1 may include a light blocking member that blocks light directed toward the second light receiving unit 13 in a direction intersecting the second light receiving axis.

[0035] Figure 2 is a diagram schematically illustrating the configuration of a smoke detection device 1 according to this modification. Figure 2(A) is a view of the cross section indicated by the dashed line in Figure 2(B) as viewed in the direction of arrow E. Figure 2(B) is a view of the cross section indicated by the dashed line in Figure 2(A) as viewed in the direction of arrow A. The smoke detection device 1 according to this modification includes a light-shielding member 19 in addition to the components included in the smoke detection device 1 according to the above-described embodiment.

[0036] The light-shielding member 19 is a cylindrical light-shielding member arranged to surround the second light-receiving unit 13. The bottom surface on the front side of the light-shielding member 19 is open so that light traveling along the second light-receiving axis (arrow D in FIG. 2(A)) can reach the second light-receiving unit 13. The light-shielding member 19 blocks light traveling along the second light-receiving axis in a direction intersecting the second light-receiving axis. The light blocked by the light-shielding member 19 includes light emitted from the first light-emitting unit 11 and traveling off the light-emitting axis of the first light-emitting unit 11 toward the second light-receiving unit 13, and light emitted from the first light-emitting unit 11 and reflected inside the container 17 toward the second light-receiving unit 13. The light-shielding member 19 serves to reduce the effect of these lights on determining the presence or absence of smoke and the type of smoke.

[0037] In this modification, the second light-emitting unit 14 may be disposed at a position where the light traveling directly from the second light-emitting unit 14 to the second light-receiving unit 13 is blocked by the light-blocking member 19. In this case, the amplitude of the signal generated by the second light-receiving unit 13 when determining whether contamination is present is smaller overall than when the light emitted by the second light-emitting unit 14 directly reaches the second light-receiving unit 13, and the amount of change in amplitude when contamination is present compared to the normal amplitude becomes more pronounced. This makes it easier for the contamination determination unit to determine the degree of contamination.

[0038] (Variation 3) The smoke detection device 1 may include a light emitting unit disposed on the second electronic circuit board 16 that emits unpolarized light for determining the degree of contamination inside the container 17.

[0039] 3 is a diagram schematically illustrating the configuration of a smoke detection device 1 according to this modification. In addition to the components included in the smoke detection device 1 according to the above-described embodiment, the smoke detection device 1 according to this modification includes a third light-emitting unit 10. The third light-emitting unit 10 is disposed on a second electronic circuit board 16. The light emitted by the third light-emitting unit 10 is directed toward a wide area within a container 17, including the smoke detection area.

[0040] In this modified example, the smoke detection unit (not shown) determines the presence or absence of smoke based on the intensity of a signal generated by, for example, the first light-receiving unit 12 during a period when the first light-emitting unit 11 is emitting light and the second light-emitting unit 14 and the third light-emitting unit 10 are not emitting light. The smoke detection unit also determines the type of smoke based on the signal generated by the first light-receiving unit 12 and the signal generated by the second light-receiving unit 13 during a period when the first light-emitting unit 11 is emitting light and the second light-emitting unit 14 and the third light-emitting unit 10 are not emitting light.

[0041] In this modified example, the contamination determination unit (not shown) determines the degree of contamination inside the container 17 based on at least one of the signals generated by the first light-receiving unit 12 and the second light-receiving unit 13 during a period when the first light-emitting unit 11 and the second light-emitting unit 14 are not emitting light and the third light-emitting unit 10 is emitting light. For example, the contamination determination unit makes the following determination.

[0042] When the intensity of the signal generated by the first light receiving unit 12 falls below the lower limit threshold, it is determined that the degree of contamination of the first light receiving unit 12 has exceeded the allowable range. When the intensity of the signal generated by the first light receiving unit 12 exceeds the upper limit threshold, it is determined that the degree of contamination of the structure, such as a wall surface facing the first light receiving unit 12, has exceeded the allowable range. When the intensity of the signal generated by the second light receiving unit 13 falls below the lower limit threshold, it is determined that the degree of contamination of the second light receiving unit 13 has exceeded the allowable range. When the intensity of the signal generated by the second light receiving unit 13 exceeds the upper limit threshold, it is determined that the degree of contamination of the structure, such as a wall surface facing the second light receiving unit 13, has exceeded the allowable range.

[0043] The above-described method of determination by the contamination determination unit is merely an example, and other methods may be employed. For example, the contamination determination unit may determine the degree of contamination inside the container 17 based on the ratio between the signal generated by the first light receiving unit 12 and the signal generated by the second light receiving unit 13.

[0044] In addition, the contamination determination unit may determine the degree of contamination inside the container 17 based on at least one of the signals generated by the first light receiving unit 12 and the second light receiving unit 13 during a period when the first light emitting unit 11 is not emitting light and the second light emitting unit 14 and the third light emitting unit 10 are emitting light simultaneously.

[0045] In addition, the contamination determination unit may determine the degree of contamination inside the container 17 based on at least one of the signals generated by the first light-receiving unit 12 and the second light-receiving unit 13 during a period when the first light-emitting unit 11 and the third light-emitting unit 10 are not emitting light and the second light-emitting unit 14 is emitting light, and based on at least one of the signals generated by the first light-receiving unit 12 and the second light-receiving unit 13 during a period when the first light-emitting unit 11 and the second light-emitting unit 14 are not emitting light and the third light-emitting unit 10 is emitting light.

[0046] For example, the contamination determination unit may determine that the degree of contamination inside the container 17 has exceeded the allowable range if the ratio between the magnitude of the signal generated by the first light receiving unit 12 during the period when only the second light emitting unit 14 is emitting light and the magnitude of the signal generated by the first light receiving unit 12 during the period when only the third light emitting unit 10 is emitting light falls outside a predetermined range.

[0047] In this modification, the third light-emitting unit 10 may be disposed at a position where the light traveling directly from the third light-emitting unit 10 to the first light-receiving unit 12 is blocked by the light-blocking member 18. In this case, the amplitude of the signal generated by the first light-receiving unit 12 when determining whether contamination is present is smaller overall than when the light emitted by the third light-emitting unit 10 directly reaches the first light-receiving unit 12, and the amount of change in amplitude when contamination is present compared to the normal amplitude becomes more pronounced. This makes it easier for the contamination determination unit to determine the degree of contamination.

[0048] The third light-emitting unit 10 employed in this modification (modification 3) may be combined with the smoke detection device 1 according to the above-described modification 2. Fig. 4 is a diagram schematically illustrating the configuration of a smoke detection device 1 according to such a combination of modifications.

[0049] In the smoke detection device 1 configured as shown in Fig. 4, the third light-emitting unit 10 may be positioned so that light traveling directly from the third light-emitting unit 10 to the second light-receiving unit 13 is blocked by the light-blocking member 19. In this case, the amplitude of the signal generated by the second light-receiving unit 13 when determining whether contamination is present is smaller overall than when the light emitted by the third light-emitting unit 10 directly reaches the second light-receiving unit 13, and the amount of change in amplitude when contamination is present compared to the normal amplitude becomes more noticeable. This makes it easier for the contamination determination unit to determine the degree of contamination.

[0050] (Other variations) The arrangement and orientation of the components of the smoke detection device 1 are not limited to those shown in Figures 1 to 4. For example, in the above-described embodiment, the first electronic circuit board 15 and the second electronic circuit board 16 are positioned on two planes that intersect perpendicularly to each other, but these two planes do not have to be orthogonal. For example, the second electronic circuit board 16 may be positioned on an inclined plane that intersects the horizontal plane at an angle of less than 90 degrees, rather than on a plane perpendicular to the horizontal plane.

[0051] Furthermore, although the smoke detection device 1 according to the above-described embodiment or the modified example thereof includes the light blocking member 18, the smoke detection device 1 does not necessarily have to include the light blocking member 18.

[0052] Furthermore, in the smoke detection device 1 according to the above-described embodiment or its modified example, when the contamination determination unit determines contamination, the first light-emitting unit 11 does not emit light, but when the contamination determination unit determines contamination, the first light-emitting unit 11 may emit light in addition to at least one of the second light-emitting unit 14 and the third light-emitting unit 10. [Explanation of symbols]

[0053] 1...smoke detection device, 11...first light-emitting unit, 12...first light-receiving unit, 13...second light-receiving unit, 14...second light-emitting unit, 15...first electronic circuit board, 16...second electronic circuit board, 17...container, 18...light-shielding member, 19...light-shielding member, 10...third light-emitting unit.

Claims

1. a first light emitting unit that emits light; a light receiving unit having a light receiving axis that intersects with the light emitting axis of the first light emitting unit; a smoke determination unit that determines whether or not smoke is present in the air based on a signal generated by the light receiving unit when the first light emitting unit emits light; a second light emitting unit that emits light; a contamination determination unit that determines that the degree of contamination of the light-receiving unit has exceeded an allowable range when the intensity of the signal generated by the light-receiving unit while the second light-emitting unit is emitting light falls below a predetermined lower threshold, and that determines that the degree of contamination of the structure facing the light-receiving unit has exceeded an allowable range when the intensity of the signal generated by the light-receiving unit while the second light-emitting unit is emitting light exceeds a predetermined upper threshold; A smoke detection device comprising:

2. When the light receiving unit is a first light receiving unit and the light receiving axis is a first light receiving axis, a second light receiving unit having a second light receiving axis that intersects with the light emitting axis of the first light emitting unit and is a light receiving axis in a direction different from the first light receiving axis; the smoke determination unit determines the type of smoke in the air based on a signal generated by the first light receiving unit when the first light emitting unit emits light and a signal generated by the second light receiving unit when the first light emitting unit emits light; The contamination determination unit determines that the degree of contamination of the second light-receiving unit has exceeded an allowable range when the intensity of the signal generated by the second light-receiving unit while the second light-emitting unit is emitting light falls below a predetermined lower threshold, and determines that the degree of contamination of the structure facing the second light-receiving unit has exceeded an allowable range when the intensity of the signal generated by the second light-receiving unit while the second light-emitting unit is emitting light exceeds a predetermined upper threshold.

10. The smoke detection device of claim 1.

3. the light emitted by the first light-emitting unit is polarized light, The light emitted by the second light emitting unit is unpolarized.

3. A smoke detection device according to claim 1 or 2.

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