Photoelectric smoke sensor

Abstract

To provide a photoelectric smoke sensor capable of reducing a load required for optical axis adjustment processing.SOLUTION: In a photoelectric smoke sensor sensing a fire by detecting attenuation of irradiation light based on a light reception amount of a light receiver, a light emitter and the light receiver includes: an optical bench mounted with an optical element and supported inclinably with respect to a housing; inclination means for inclining the optical bench in an arbitrary direction when viewed from a center of the optical bench; a storage section for storing a light reception amount measured when temporary adjustment is performed as a reference light reception amount and also storing a light reception amount measured when the optical bench is inclined by the inclination means as a measurement light reception amount; and a control section for controlling the inclination means. The control section performs the elevation control of the optical bench so as to form a predetermined angle from a direction of the optical bench in temporal adjustment, controls the inclination means so as to allow the optical bench to rotate while keeping the angle, also obtains each change amount of each of the measurement light reception amounts with respect to the reference light reception amount, and, therefrom, determines, as an adjustment direction, a direction where a measurement light reception amount is plus or equal to or more than a fixed amount.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] This invention relates to a photoelectric smoke detector, and relates to technology that can be effectively used in, for example, a photoelectric separated detector in which a light emitter and a light receiver are separately constructed in different housings and installed facing each other, and which detects a fire by detecting the attenuation of light irradiated onto the light receiver due to smoke generated by a fire. [Background technology]

[0002] For a photoelectric separated sensor to exhibit the desired performance, it is a prerequisite that the optical axes of the optical systems of the light transmitter 10 and the light receiver 30 are aligned, as shown in Figure 11(A). For this reason, the light emitter and light receiver that make up a photoelectric separated sensor are generally provided with an optical axis adjustment mechanism that adjusts the optical axis by changing the tilt of the element substrate on which the lens, light emitting element, or light receiving element is mounted, or the optical bench. Examples of optical axis adjustment mechanisms for conventional photoelectric separated sensors include those disclosed in Patent Documents 1 and 2.

[0003] In the photoelectric separated sensors disclosed in Patent Documents 1 and 2, the element substrate or optical bench is supported so that it can rotate around mutually perpendicular vertical and horizontal axes, and an adjustment screw is provided between this element substrate or optical bench and the housing in a direction perpendicular to the element substrate or optical bench.By turning the knob on the adjustment screw to widen or narrow the gap between the element substrate or optical bench and the housing, the element substrate or optical bench can be tilted in any direction, up, down, left, or right. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 04-191998 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-184572 [Patent Document 3] Japanese Patent Application Publication No. 2019-96270 Summary of the Invention [Problem to be solved by the invention]

[0005] However, with conventional photoelectric separated sensors, the installer must visually check the tilt of the element substrate or optical bench while turning the adjustment screw knob to make adjustments, which places a heavy burden on the worker and makes it difficult for beginners who are not accustomed to the work to make precise adjustments, requiring a high level of skill from the worker. On the other hand, Patent Document 3 discloses an invention in which, instead of using an adjustment screw with a knob, a piezoelectric actuator is provided between the element substrate or optical bench and the housing, making it possible to automatically adjust the tilt of the element substrate or optical bench.

[0006] However, in the invention described in Patent Document 3, a piezoelectric actuator is provided between the housing and the optical base (element substrate) of the light emitter and the light receiver, and the amount of light received is obtained by changing the orientation of the light emitting element over the entire operating range of the piezoelectric actuator, and a global optimal solution is found to adjust to the orientation that maximizes the amount of light received, which poses the problem of a large burden being placed on the optical axis adjustment process.

[0007] This invention has been made in consideration of the above-mentioned problems, and aims to provide a photoelectric smoke detector that can reduce the burden required for adjusting the optical axis by finding a local optimal solution. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides: A photoelectric smoke detector comprising: a light emitter having a light emitting element and a housing for accommodating the light emitting element; and a light receiver disposed opposite the light emitter and having a light receiving element for receiving the light emitted from the light emitting element, the photoelectric smoke detector detecting attenuation of the light emitted by smoke in a monitored space based on the amount of light received by the light receiver, and detecting a fire, The light emitter and / or the light receiver are an optical table that has an optical element mounted thereon and is tiltably supported with respect to the housing; tilting means for tilting the optical bench in any direction from its center; a light emitter storage unit that stores the amount of received light measured when the optical axis alignment between the light emitter and the light receiver is temporarily adjusted as a reference amount of received light, and stores the amount of received light measured when the optical bench is tilted by the tilting means as a measured amount of received light; a control unit that controls the tilting means based on a comparison result between the reference amount of received light and the measured amount of received light, with the orientation of the optical bench at the time of the temporary adjustment as a reference; and The control unit controlling the tilting means to tilt the optical bench so that it forms a predetermined angle with respect to the direction of the optical bench at the time of the temporary adjustment; and controlling the tilting means to rotate the optical bench while maintaining the angle; The amount of change between the reference amount of received light and the plurality of measured amounts of received light is calculated, and the direction in which the amount of change is positive and equal to or greater than a certain level is determined as the adjustment direction. The tilting means is driven and controlled to orient the optical bench in that direction, thereby setting the tilt of the optical bench.

[0009] In the above description, the term "optical element" refers to a light-emitting element in the case of a light emitter (light transmitter), and a light-receiving element in the case of a light receiver. With a photoelectric smoke detector having the above configuration, the adjustment direction is determined by finding the amount of change in the measured amount of received light relative to the reference amount of received light in multiple directions, rather than in pairs in all directions. In other words, this is equivalent to finding a local optimal solution, so the burden required for the optical axis adjustment process can be reduced.

[0010] Here, the control unit is configured to drive and control the tilting means so as to tilt the optical bench in a direction in which the difference between any two adjacent change amounts among the plurality of change amounts becomes equal to or less than a predetermined value. With this configuration, it is not necessary to change the orientation of the light-emitting element over the entire operating range of the optical bench to obtain the amount of light received and to find a global optimal solution, thereby reducing the burden on the control unit (CPU) required for the optical axis adjustment process.

[0011] The control unit may be configured to drive and control the tilting means so as to tilt the optical bench in a direction in which the measured amount of received light that maximizes the amount of change is obtained. According to this configuration, it is not necessary to find a global optimum solution, so the load on the control unit (CPU) required for the adjustment process of the optical axis can be reduced.

[0012] Alternatively, the control unit may be configured to drive and control the tilting means to tilt the optical bench in a direction that is a vector synthesis of the directions when each of the measured amounts of received light was obtained for a plurality of the measured amounts of received light, including the maximum amount of change. According to this configuration, it is not necessary to find a global optimum solution, so the load on the control unit (CPU) required for the adjustment process of the optical axis can be reduced.

[0013] Preferably, the tilting means is interposed between the housing and the optical bench and is configured by a piezoelectric actuator capable of changing the tilt of the optical bench relative to the housing. According to this configuration, the tilting device can be configured using existing technology, which reduces the burden on device design and ultimately prevents costs from increasing.

[0014] The invention of the present application is a photoelectric smoke detector that includes a light emitter having a housing that houses a light emitting element and a lens disposed in front of the light emitting element so that their optical axes coincide with each other, and a light receiving element disposed opposite the light emitter and that receives the irradiated light emitted from the light emitting element, and a lens disposed in front of the light receiving element so that their optical axes coincide with each other, and that detects attenuation of the irradiated light due to smoke in a monitored space based on the amount of light received by the light receiving element, thereby detecting a fire, The light emission The vessel , The light emission an optical table that is mounted with an element and is tiltably supported with respect to the housing; tilting means for tilting the optical bench in any direction from the center of the optical bench; a storage unit that stores the amount of received light measured when the tilting means tilts the optical bench as a measured amount of received light; a control unit that controls the tilting means based on an initial installation direction, which is the direction of the optical axis of the optical bench passing through the center of the optical bench when the light emitter and the light receiver are initially installed; and The light emission vessel The optical bench includes: Illumination The element Illumination The optical axis of the element is set to coincide with the optical axis of the optical bench; The control unit The optical table is tilted and controlled so as to form a predetermined angle from the initial installation direction, and the optical table is tilted and controlled while maintaining the angle. At least one lap controlling the tilting means to pivot; A change amount between the plurality of measured amounts of received light and a reference amount of received light in the initial installation direction is calculated, Each time the turning control for one revolution is completed, The direction in which the measured amount of received light is changed to a positive value and is equal to or greater than a certain value is determined as the adjustment direction, and the tilting means is driven and controlled to orient the optical bench in that direction, thereby setting the tilt of the optical bench; on the other hand, if any of the measured amounts of received light are equal to or less than a certain value, the angle is reset to a larger value, and the tilting means is controlled again to rotate the optical bench while maintaining the reset angle.

[0015] With a photoelectric smoke detector having the above configuration, even if the irradiation position of the light beam emitted from the light emitter during initial setting is outside the light receiving area (lens) of the light receiver, the adjustment direction can be appropriately determined and optical axis alignment can be performed. [Effects of the Invention]

[0016] The photoelectric smoke detector according to the present invention can reduce the burden of adjusting the optical axis by finding a local optimum solution. It also has the advantage of being able to appropriately determine the adjustment direction and align the optical axis even when the irradiation position of the light beam emitted from the light emitter during initial setup is outside the lens. [Brief explanation of the drawings]

[0017] [Figure 1] 1A and 1B are diagrams showing an example of a separate-type photoelectric smoke detector to which the present invention is applied, in which (A) is a front view and (B) is a side view. [Figure 2] FIG. 1 is an explanatory diagram showing the operating principle of a tilting device as a driving stage that uses a piezoelectric actuator provided in a light transmitter (light emitter) that constitutes an embodiment of a photoelectric smoke detector, where (A) shows the state before adjustment and (B) shows the state after adjustment. [Figure 3] 2A and 2B are explanatory diagrams showing the relationship between the irradiation position on the lens of the light receiver that receives light irradiated from the light transmitter in FIG. 1 and the amount of light received, where (A) is a diagram showing an example of the irradiation position on the lens, and (B) is a diagram showing the amount of light received at that time. [Figure 4] 10A is a diagram showing the case where the irradiating position on the lens is changed by tilting the optical bench, and FIG. 10B is a diagram showing the amount of light received at each irradiating position. [Figure 5] 4(A) and 4(B). FIG. 4(B) is a diagram showing the change in the amount of received light as a difference between the amount of received light at each of the irradiation positions #1 to #8 in FIG. 4(A) and the amount of received light A0 at the reference position. [Figure 6] 10 is a diagram showing the change in the amount of received light as the difference between the amount of received light at each of the irradiation positions #1 to #8 and the amount of received light A0 at the reference position after tilt adjustment by the tilting device. FIG. [Figure 7] FIG. 10 is a diagram showing the change in the amount of received light from the reference position at each of irradiation positions #1 to #8, the boundary between the area where the slope of the change is positive and the area where the slope is negative, and the adjustment direction. [Figure 8] 10 is a diagram showing the relationship between the angle θ and three directions, namely, the direction closest to the correct adjustment direction from the reference direction X, and the direction second closest to that direction and the direction third closest to that direction. [Figure 9] 10 is a diagram showing the relationship between the angle θ from the reference direction X and the gradient of the change in the amount of received light. FIG. [Figure 10] 10 is a diagram showing the relationship between the difference (ΔAmax−ΔAmin) between the maximum value ΔAmax and the minimum value ΔAmin of the amount of change ΔA in the amount of received light and the correction coefficient Wr. [Figure 11]The diagrams show the arrangement of the light transmitter and receiver, where (A) shows a state in which their optical axes are aligned, and (B) shows a state in which their optical axes are not aligned. [Figure 12] 10A shows the concept of optical axis alignment in the second embodiment, where FIG. 10A is a diagram showing an example of the relationship between the lens and the irradiation position of the light beam in the initial installation state, and FIGS. 10B to 10D are diagrams showing cases where the irradiation position on the lens is changed by tilting the optical bench when the irradiation position of the light beam in the initial installation state is different. DETAILED DESCRIPTION OF THE INVENTION

[0018] An embodiment of the present invention applied to a photoelectric separated sensor will be described below with reference to the drawings. A photoelectric separated sensor comprises a light transmitter (light emitter) that emits light and a light receiver that receives the light emitted from the light transmitter, and the present invention is applied to the light transmitter. Figure 1 shows an example of the configuration of a light transmitter to which the present invention is applied, with (A) being a front view and (B) being a partially cross-sectional side view.

[0019] First Embodiment As shown in Figure 1, the light transmitter (light emitter) 10 of this embodiment includes a box-shaped main body case 11, a light transmission unit 12 housed in the main body case 11, adjustment screws 13A and 13B for manually temporarily adjusting the tilt of the light transmission unit 12, a tilting device 14 equipped with a piezoelectric actuator for automatically adjusting the tilt of the light transmission unit 12, and a control device 15 consisting of a CPU (microprocessor) and the like for driving and controlling the tilting device 14. The adjustment screws 13A and 13B are provided with knobs 13a and 13b at their heads, respectively. A spring 60 interposed between the locking piece 11a at the front end of the main body case 11 and the light transmitting unit 12 is fitted onto the adjustment screw 13B.

[0020] The light-transmitting unit 12 comprises a storage frame 21 that is open at the front (left side in Figure 1 (B)), a light-emitting element 22 arranged at the back (rear wall) of the storage frame 21, a lens 23 arranged in front of the light-emitting element 22, and holding frames 24A and 24B that hold the storage frame 21, and is configured so that light emitted from the light-emitting element 22 is irradiated forward by the lens 23. The holding frame 24A is rotatably attached to the main body case 11 by a pair of horizontal support shafts 25 on the left and right, and the holding frame 24B is rotatably attached to the holding frame 24A by a pair of vertical support shafts (not shown) on the top and bottom that are provided between the holding frame 24A and the holding frame 24B. Furthermore, lens 23 is a convex lens, and in light-sending unit 12 that includes this convex lens and light-emitting element 22 as an optical element, light-emitting element 22 is installed with its optical axis aligned at the focal point of lens 23, which is a convex lens, and light emitted from light-emitting element 22 is emitted as parallel light rays parallel to the optical axis by lens 23. Similar to light-sending unit 12, light-receiver (light-receiving unit) also includes a convex lens and a light-receiving element that is installed with its optical axis aligned at the focal point, and parallel light rays that are incident on the lens of the light-receiver and are parallel to the optical axis of the lens are focused on the light-receiving element.

[0021] When the knob 13a of the adjustment screw 13A is turned, the holding frame 24A is rotated about a horizontal support shaft 25, thereby changing the vertical tilt. On the other hand, when the knob 13b of the adjustment screw 13B is turned, the holding frame 24B is rotated about a vertical support shaft (not shown), thereby changing the horizontal tilt. This stage structure, which allows tilting in any direction up, down, left, or right using two orthogonal axes, is a well-known technology, as described in, for example, Patent Document 2, and therefore a detailed illustration of the structure is omitted.

[0022] As shown in FIG. 2, the tilting device 14 includes piezoelectric actuators 42A to 42D arranged at the four corners of the lower surface of a substrate 41 serving as an optical table on which the light emitting element 22 is mounted. By selectively applying voltage to the piezoelectric actuators 42A to 42D, top and bottom Left and right, 360 degrees in any direction Within an angle range of less than 180 degrees The base plate 41 is configured to be tiltable. In FIG. 1, the rear wall of the housing frame 21 of the light-transmitting unit 12 corresponds to the base plate (optical bench) 41 shown in FIG. Furthermore, the lens 23 is fixed to the front of the storage frame 21, and when the substrate 41 is tilted by the piezoelectric actuators 42A to 42D, the storage frame 21, the light emitting element 22 therein, and the front lens 23 are tilted together. The piezoelectric actuators 42A to 42D expand and contract by an amount corresponding to the applied voltage in response to a drive signal from the control device 15. In FIG. 2, the piezoelectric actuator 42D is hidden behind the substrate (optical bench) 41 and is not visible. The light-emitting element 22 as an optical element is placed on the substrate (optical bench) 41 so that the direction of the optical axis of the light-emitting element 22 coincides with the direction of the substrate (optical bench) 41, and the lens 23 is arranged in front of the light-emitting element 22 (above in Figure 2) so that its optical axis coincides with the optical axis of the light-emitting element 22.

[0023] In this embodiment, since it is difficult to achieve high-precision adjustment by manually adjusting the tilt of the light-sending unit 12 using the adjustment screws 13A and 13B, after a manual temporary adjustment, the control device 15 controls the tilting device 14 to change the tilt of the storage frame 21 of the light-sending unit 12, while acquiring the amount of light received detected by the light receiver disposed opposite, and calculates the optimum tilt direction (tilting direction) and adjustment amount by calculation, determines the tilt of the light-sending unit 12, and adjusts it using the tilting device 14. Below, a specific procedure for calculating the optimum tilt direction and adjustment amount will be described in detail.

[0024] Fig. 3(A) shows an example of the position of light irradiated from the light transmitter 10 onto the lens (light receiving element) L on the light receiver side after manual adjustment. In Fig. 3(A), the mark C in the center of the circle L representing the lens indicates the ideal irradiation position, and the mark #0 in the upper left indicates an example of the irradiation position immediately after manual adjustment when the optical axes of the optical systems of the light transmitter 10 and the light receiver 30 are misaligned as shown in Fig. 11(B).

[0025] Figure 3(B) is a graph showing the amount of light received by the light receiver, Ac, A0, when the light (beam) from the light transmitter 10 is irradiated so that its center coincides with the position of the mark C and #0. The amount of light received is greatest (Amax) when the light is irradiated onto the center C of the lens L.

[0026] In FIG. 4A, in a state where light from the light transmitter 10 is irradiated at position #0, the control device 15 controls the tilting device 14 to tilt the storage frame 2 of the light-transmitting unit 12. 1 of The figure shows a circle indicating the locus of the irradiation position when the tilt is changed by 45 degrees from the center of #0 through 360 degrees, and examples of light irradiation positions #1 to #8 on the light receiver side. The reason why there is an amount of light received on the light receiver side even at positions #1 to #3 outside the lens L is that even though the light emitted from the light transmitter 10 is a beam, it spreads to a certain extent.

[0027] Figure 4(B) shows a graph of the amounts of light received A1 to A8 at the above-mentioned irradiation positions #1 to #8. From Figures 3(B) and 4(B), when considering the difference between the amounts of light received A1 to A8 at #1 to #8 and the amount of light received A0 at #0, it can be seen that the difference between the amount of light received A6 at #6 and the amount of light received A0 at #0 is the largest, and therefore it can be inferred that the tilt of the optical bench should be adjusted by controlling the tilting device 14 so that the irradiation position of light from the light transmitter 10 side is at position #6 among #1 to #8. The size of the radius R of the circle showing the locus of the irradiation position is arbitrary, but can be set to be approximately the same as the radius of the lens L, for example.

[0028] 4(A), a relatively accurate adjustment result can be obtained by selecting position #6 based on the positional relationship between irradiation position #0 immediately after manual adjustment and center C of lens L, but depending on irradiation position #0 immediately after manual adjustment, a position between #5 and #6 or a position between #6 and #7 may be optimal. Therefore, the optical bench may be tilted in a direction such that the difference between any two adjacent change amounts is equal to or less than a predetermined value.

[0029] In addition, the amount (angle) of tilting the optical bench depends not only on the distance (monitoring distance) between the light transmitter 10 and the light receiver 30, but also on the amount of tilt of the optical bench immediately after manual adjustment, i.e., the distance from the irradiation position #0 to the center C of the lens L. Therefore, after adjusting the tilt of the optical bench by controlling the tilting device 14 in the direction that the irradiation position is at position #6, the amount of light received A1 to A8 at positions #1 to #8 is measured again using the above method while changing the tilt of the optical bench, and the position where the difference with the amount of light received at #0 is greatest is found, and the direction in which to tilt the optical bench is determined. In other words, the optical bench is rotated at least once through 360 degrees to determine the tilt direction of the optical bench. By repeating this process several times, the optimum adjustment direction and adjustment amount (tilt angle) can be determined.

[0030] 5, graphs (a) to (h) show the amount of received light when the irradiation position is moved from irradiation position #0 immediately after manual adjustment to positions #1 to #8 that are each equidistant from #0, and the difference between the amount of received light A0 at each position and that at #0, i.e., the change in the amount of received light relative to A0. Also, FIG. 6, graphs (a) to (h) show the amount of received light when the irradiation position is moved from irradiation position #0 immediately after adjustment to positions #1 to #8 after the tilt of the optical bench is adjusted using tilting device 14, and the change in the amount of received light relative to A0. When the optical bench is adjusted so that the irradiation position, i.e., the center of the beam, is nearly aligned with the center of the lens, graphs (a) to (h) will be nearly the same, as shown in Figure 6, and adjustment is considered complete when this state is reached. The same applies when tilting the optical bench in a direction such that the difference between any two adjacent change amounts is equal to or less than a predetermined value.

[0031] Next, a method for calculating the tilt direction and adjustment amount (tilt angle) with high accuracy will be described. In Figure 7, which shows the change in the amount of received light when the beam irradiation position is moved from irradiation position #0 immediately after manual adjustment to positions #1 to #8 that are each equidistant, we calculate the slope of each graph (a) to (h) and check its sign. We find that the slopes of (a) to (d) and (h) are negative, while the slopes of (e) to (g) are positive. Furthermore, if we draw a line at the boundary between the negative and positive slope signs of the graphs, we get dashed line B. Therefore, we can see that the adjustment direction is perpendicular to line B, as shown by arrow D in Figure 7.

[0032] However, there are cases where the optimum adjustment direction is a direction between #5 and #6 or a direction between #6 and #7. Even in such cases, in this embodiment, the weighting coefficient W θ Using this, weighting was performed for each direction from the irradiation position #0 immediately after manual adjustment to the irradiation positions #1 to #8. Specifically, as shown in FIG. 8, if the direction closest to the correct adjustment direction from the reference direction X is θ1, the next closest direction is θ2, and the next closest direction is θ3, then the following equation is used: Adjustment direction=W θ1 θ1+W θ2 θ2+W θ3 θ3 The adjustment direction is determined by

[0033] In the above formula, three directions are considered: the closest direction and the second and third closest directions from that direction; however, depending on the number of irradiation positions, it may be possible to consider up to the fourth closest direction or the fifth closest direction. Here, the weighting coefficient W θ1 ,W θ2 ,W θ3 is W θ1 +W θ2 +W θ3 For example, if the slopes of the graphs of the amounts of received light (or the amount of change ΔA in the amount of received light) in Figures 7(a) to (h) corresponding to θ1, θ2, and θ3 have the relationship shown in Figure 9, then assuming that they follow a normal distribution, W θ1 =0.5,W θ2 =0.3,W θ3 =0.2. This makes it possible to set the direction of arrow D shown in Fig. 7 as the adjustment direction by the tilting device 14. In other words, for a plurality of measured amounts of received light including the largest amount of change, the direction obtained by vector synthesis of the directions when the respective measured amounts of received light were obtained can be determined as the adjustment direction, and the optical bench can be tilted in that direction.

[0034] On the other hand, for the adjustment amount (tilt angle), consider a correction coefficient Wr that increases in proportion to the gradient of the graphs of the amount of received light in each of Figures 7(a) to 7(h), that is, the difference (ΔAmax-ΔAmin) between the maximum value ΔAmax and the minimum value ΔAmin of the amount of change ΔA. For example, as shown in Figure 10, when the difference (ΔAmax-ΔAmin) between the maximum value and the minimum value of the amount of change ΔA is taken on the horizontal axis, the correction coefficient Wr is expressed as a linearly increasing increasing function, and is calculated using the following equation: Adjustment amount = Wr |ΔAmax-ΔAmin| The adjustment amount is calculated by the following. Here, a large difference between the maximum value ΔAmax and the minimum value ΔAmin means that the current tilt of the optical bench from its normal position is large, that is, the irradiation position of the light (beam) from the light transmitter is significantly deviated from the center of the lens, and therefore, by using the above correction coefficient Wr, the optimal adjustment amount by the tilting device 14 can be set.

[0035] In this embodiment, the amount of received light measured when the operator tentatively adjusts the optical axis alignment between the light transmitter and the light receiver is stored in their own memories as a reference amount of received light, and the amount of received light measured when the optical bench is tilted by the tilting device 14 is stored as a measured amount of received light. The control device 15 of the light transmitter 10 executes a process to calculate the adjustment direction and amount according to the above procedure, and stores the obtained results in memory. When performing smoke detection processing, the control device 15 drives and controls the tilting device 14 based on the adjustment direction and amount stored in memory, and turns on the light-emitting device 22 to irradiate the light receiver 30 with detection light.

[0036] <Second embodiment> In the first embodiment described above, when installing the photoelectric smoke detector of the present invention, the operator in charge of installation first manually aligns the orientation of the light emitter and the light receiver as much as possible, and then performs processes such as changing the orientation of the optical table. According to the adjustment method of the first embodiment, the optical axes of the light emitter and the light receiver are first roughly aligned using the operator's knowledge, and then the control device 15 controls the piezoelectric actuator to tilt the optical bench, thereby enabling the optical axes to be automatically aligned with high precision.

[0037] Next, a second embodiment that enables adjustment without manual temporary adjustment by an operator will be described with reference to FIG. Figure 12(A) shows a schematic diagram of the relationship between the lens L of the receiver and the degree of incidence of the light beam at measurement point #0 in Figure 4(A), and the symbol 121 represents the irradiation range of the light beam that reaches the receiver with a spread relative to the lens L of the receiver.

[0038] As can be seen from FIG. 12(A), even in the case of #0 where the reference amount of received light is used, not all of the light emitted from the light transmitter is necessarily received by the light receiver. In order to illustrate the concept of the second embodiment, Figure 12 shows the lens L as having a sufficient space around it, but in an actual device, as can be seen from Figure 1(A), the main body case 11 exists around the lens 23.

[0039] Fig. 12(B) shows the light beam irradiation ranges 121 at measurement points #1 to #8 shown in Fig. 4(A) in an overlapping manner. As can be seen from Fig. 12(B), the amount of received light differs depending on the irradiation position, as explained above with reference to Fig. 4(B). Figure 12(C) shows a schematic diagram of a state in which the light beam irradiation position deviates significantly from lens L depending on the orientation of the optical bench (initial installation orientation) at the time of initial setup, and almost no light is incident on lens L at any of measurement points #1 to #8.

[0040] In the case of Fig. 12(C), the amount of light received at each irradiation position does not show a certain degree of difference between measurement points as shown in Fig. 4(B), and the amount of light received at each measurement point is close to 0. Therefore, in such a case, it is difficult to immediately adjust the orientation of the optical bench as described in the first embodiment. Therefore, in the second embodiment, the control device 15 resets the radius R of the circle of movement of the irradiation position to a larger value. How much larger it is depends on the actual device as a design matter, but it can be enlarged by, for example, the radius or diameter of the lens L. Alternatively, if it is known from the device specifications or has been experimentally measured separately, it may be set to match the diameter of the light range 121 in FIG. 12(A).

[0041] 12(D) is a schematic diagram showing the irradiation range 121 of the light beam at each of measurement points #1 to #8 when the radius R of the circle of movement of the irradiation position is set larger than that of FIG. 12(C). As can be seen from the figure, light can be incident on lens L at least at #6, and therefore, by comparing the reference amount of received light at #0, control device 15 can determine that it is necessary to control the tilting means to tilt the optical bench so that the amount of received light is directed toward #6.

[0042] Here, as can be seen from Figure 12(D), the irradiation range 121 of the light beam cannot be made large, so if the radius R of the moving circle of the irradiation position is increased, gaps will occur between the irradiation ranges 121 of the light beam at each measurement point #1 to #8, and in the case of the same figure, it is not possible to expect a more accurate judgment than simply pointing in the direction of #6. Therefore, the control device 15 may increase the number of measurement points in accordance with an increase in the radius R of the circle of movement of the irradiation position. For example, when the radius R exceeds the radius of the lens L, the number of measurement points is doubled, and the measurement points are set more finely to acquire the measured amount of received light. Alternatively, as the radius R is increased and light begins to enter the lens L, the amount by which the radius R is increased can be set smaller (finer) than before, and the measured amount of received light can be repeatedly obtained.The radius R at which the maximum amount of measured received light is obtained can then be identified, and the orientation of the optical bench 41 can be readjusted using the adjustment method in the first embodiment. When determining the tilt direction of the optical bench 41, the optical bench is rotated at least once through 360 degrees.

[0043] While the present invention has been described above based on the embodiments, the present invention is not limited to the above embodiments and can be modified as appropriate without departing from the spirit of the present invention. For example, in the above embodiments, it has been described that the amount of received light is acquired while changing the irradiation direction from the light transmitter 10 to the light receiver 30 at eight positions by 45 degrees around the irradiation position immediately after manual adjustment, but the number of irradiation positions is not limited to eight and may be at least three.

[0044] Furthermore, in the above embodiment, it has been explained that the process of calculating the adjustment direction and adjustment amount is configured to be performed by the control device 15 of the light transmitter 10, but it is also possible to provide a dedicated test device, and have the test device irradiate light from the manually adjusted light transmitter 10 to the light receiver while changing the irradiation direction according to the procedure described above, obtain the amount of light received from the light receiver, calculate the adjustment direction and adjustment amount, and write the calculation results to the memory in the control device 15 of the light transmitter 10.

[0045] Furthermore, in the above embodiment, a piezoelectric actuator is provided in the light transmitter 10, and the optical axis is adjusted by changing the orientation of the optical bench, but an optical axis adjustment mechanism including a piezoelectric actuator may also be provided on the optical bench on the light receiver side that mounts the light receiving element. In this case, however, the optical bench on the light receiver side is adjusted by changing the orientation in the opposite direction to the adjustment direction of the optical bench on the light transmitter side. In addition, in the above embodiment, the present invention is described as being applied to a photoelectric separated sensor in which the light transmitter and light receiver are configured in separate housings, but the present invention can also be applied to a type of smoke sensor in which the light emitting element and the light receiving element are arranged opposite each other inside a single housing. [Explanation of symbols]

[0046] 10 Light transmitter (light emitter) 11 Main unit case 12 Light transmitting unit 13A, 13B adjustment screws 14 Tilt device 15 Control device 21 Storage frame 22 Light-emitting elements (optical elements) 23 Lens 24A, 24B holding frame 25 Horizontal support shaft 30 Receiver 41 Substrate (optical bench) 42A~40C Piezoelectric Actuator

Claims

[Claim 1] A photoelectric smoke detector comprising: a light emitter having a housing that houses a light emitting element and a lens disposed in front of the light emitting element so that their optical axes coincide; and a light receiving element disposed opposite the light emitter and that receives the irradiated light emitted from the light emitting element, and a lens disposed in front of the light receiving element so that their optical axes coincide; the detector detects attenuation of the irradiated light due to smoke in a monitored space based on the amount of light received by the light receiving element, thereby detecting a fire, The light emitter is an optical table that is mounted with the light emitting element and is tiltably supported with respect to the housing; tilting means for tilting the optical bench in any direction from the center of the optical bench; a storage unit that stores the amount of received light measured when the tilting means tilts the optical bench as a measured amount of received light; a control unit that controls the tilting means based on an initial installation direction, which is the direction of the optical axis of the optical bench passing through the center of the optical bench when the light emitter and the light receiver are initially installed; and the light emitting element is installed on the optical bench of the light emitter so that the direction of the optical axis of the light emitting element coincides with the direction of the optical axis of the optical bench; The control unit controlling the tilting means to tilt the optical table so that it forms a predetermined angle from the initial installation direction, and further controlling the tilting means to rotate the optical table at least one revolution while maintaining the angle; The amount of change between the plurality of measured amounts of received light and the reference amount of received light in the initial installation direction is calculated, and each time one revolution of the rotation control is completed, the direction in which the amount of change is positive and equal to or greater than a certain level is determined as the adjustment direction, and the tilting means is driven and controlled to orient the optical bench in that direction, thereby setting the tilt of the optical bench. On the other hand, if any of the measured amounts of received light are equal to or less than a certain level, the angle is reset to a larger value, and the tilting means is controlled again to rotate the optical bench while maintaining the reset angle. A photoelectric smoke detector characterized by:

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