JP5280655B2 - Dimming sensor - Google Patents

Description

  The present invention relates to a light-reducing sensor that detects the attenuation of light that has been projected from a light projecting unit and passed through a space that is a monitoring area and reached a light receiving unit, and senses the presence of smoke caused by a fire or the like.

  Conventionally, in order to detect the occurrence of a fire, a smoke detector that detects smoke generated with the fire has been used. One method of detecting smoke is to detect the attenuation of light intensity when light (for example, near-infrared rays) passes through the smoke. Sensors that use this method are called dimming sensors. ing. The dimming sensor includes a light receiving unit and a light projecting unit. The light projecting / receiving unit projects and receives signal light, and the signal light projected from the light projecting / receiving unit is reflected toward the light projecting / receiving unit. There is a dimming reflection type detector in which a reflecting plate is disposed opposite to each other on a wall surface, and a region sandwiched between the light projecting / receiving unit and the reflecting plate is a monitoring region. In addition, a light projecting unit that projects signal light and a light receiving unit that is disposed opposite to the light projecting unit and that receives signal light are provided one by one, and the area sandwiched between the light projecting unit and the light receiving unit is monitored. A dimming separation type sensor as a region is also used. When smoke intervenes in the monitoring area of these light-reducing detectors, the smoke is present in the path from when the signal light is projected from the light projecting unit and received by the light receiving unit. And the occurrence of fire is detected based on this (see, for example, Patent Document 1).

JP-A-11-238185

By the way, in order to expand the application range of the dimming sensor, the maximum monitoring distance is required to be increased. However, the attenuation of the signal light accompanying the increase in the monitoring distance is a limitation. Since the signal light projected from the light projecting unit propagates through the monitoring region while diffusing, the optical power density of the signal light attenuates in inverse proportion to the square of the propagation optical path length. That is, the propagation optical path length is L, the optical power density at the time of projection from the light projecting / receiving unit is D0, the optical power density of the signal light at the time of propagation of the distance L is D1, and the predetermined proportionality constant is α. Then, the ^{D1 = α × D0 / L 2} . According to this formula, for example, the optical power density of the signal light emitted from the light projecting unit and propagated a distance of 100 m is attenuated to 1/10000 of the optical power density at the time of propagating a distance of 1 m from the light projecting unit. doing.

Further, in the dimming reflection type detector, the signal light needs to reciprocate between the light projecting / receiving unit and the reflecting plate. The distance (monitoring distance) between the light projecting / receiving unit and the reflecting plate is L2, the optical power density at the time when the light is projected from the light projecting / receiving unit is D0, and the signal light at the time when the light is projected from the light projecting / receiving unit Is D1, the optical power density of the signal light when it is reflected by the reflector and reaches the light projecting and receiving unit is D2, and the predetermined proportionality constant is β, D2 = β × {α × (D0 / L2 ² )} / L2 ² = α × β × D0 / L2 ⁴ . That is, as a whole, the optical power density is attenuated in inverse proportion to the fourth power of the installation interval (monitoring distance) between the light projecting / receiving unit and the reflecting plate.

  As described above, when the monitoring distance in the dimming sensor is increased, that is, when the propagation path length of the signal light is increased, the optical power density of the signal light projected from the light projecting unit is given to the light receiving unit. At the time of arrival, it is greatly attenuated, and the S / N ratio as a sensor is greatly deteriorated.

  As described above, there is a demand for extending the maximum monitoring distance of the dimming sensor. In particular, the dimming reflection type sensor connects the light projecting unit and the light receiving unit, which are necessary for the dimming separation type sensor. Compared to the dimming sensor, which requires no wiring, there is a greater advantage in installation work when applied to large spaces, and there is an increasing demand for an increase in the maximum monitoring distance. However, because of the reflection type, the propagation path length of the signal light is twice that of the dimming separation type sensor that monitors the same distance. The maximum monitoring distance was inevitably shorter than the dimming separation type sensor. For example, the maximum monitoring distance of the conventional dimming type separation type sensor is about 100 m, whereas the dimming type reflection type sensor having equivalent light projection performance is about 30 m. In response to such a request to increase the maximum monitoring distance, if the monitoring distance is simply increased as it is in the past in a dimming reflection type sensor, the S / N ratio will be further lowered, so improvement is desired. It had been.

  On the other hand, when dealing with simply increasing the signal amplification degree at the light receiving unit, noise components caused by disturbance light or the like are simultaneously amplified, and the operation of the amplifier circuit becomes unstable. It was difficult to avoid deterioration of the / N ratio.

  Also, as a countermeasure from the optical side, a large-diameter projection lens (generally made of resin such as acrylic) is used in the projection unit, and the distance between the light source (generally a near infrared LED) and the projection lens is set. By enlarging (increasing the focal length), it is possible to increase the optical power density (light projection efficiency) of the light projected from the light projecting unit. However, since the size of the dimming sensor, particularly the depth dimension, is large, there are significant restrictions on the installation of the dimming sensor. In addition, there is a limit to the increase in the optical power density because the larger the diameter of the projection lens, the greater the aberration of the outer periphery of the effective diameter of the projection lens. Furthermore, even if the projection lens has a large diameter, it is impossible to project signal light having power exceeding the power supplied to the projection unit from the projection unit, and one light source emits light. The above energy cannot be extracted in the first place. In order to extend the monitoring distance while keeping the light reception amplification level within a predetermined range, and to obtain a good S / N ratio, a drastic countermeasure that has not been taken until now has been required. In addition, there exists a problem that the difficulty in manufacturing management and quality control increases in enlargement of a lens.

  In addition, when a so-called retroreflecting plate that reflects incident light in the incident direction is used in the dimming reflection type detector, the signal light reflected by the reflecting plate and reaching the light projecting / receiving unit is transmitted to the light projecting unit. Has a distribution of optical power density with the peak center. Therefore, when the diameter of the light projecting lens is increased, the distance between the light projecting part and the light receiving part (the distance between the light projecting axis and the light receiving axis) also increases, so that the light receiving part is separated from the peak of the optical power density distribution. There has been a problem that light is incident only on a part of the light receiving lens. For this reason, conventionally, there has been no effective method for improving the S / N ratio in response to a request for increasing the maximum monitoring distance of the dimming sensor.

  The present invention has been made in view of the above, and without increasing the depth dimension of the dimming sensor, efficiently improves the optical power density of the signal light projected from the light projecting unit, An object of the present invention is to provide a dimming sensor having a significantly improved S / N ratio.

In order to solve the above-described problems and achieve the object, the light-reducing sensor according to claim 1 receives the signal light projected from the light projecting unit with respect to the monitoring region by the light receiving unit, A dimming sensor that determines the presence or absence of a predetermined monitoring target in the monitoring area based on information output from the light receiving means, and projects the signal light so that the light can be received by one light receiving means. A plurality of light projecting means that illuminate, and a setting means that sets the number of the light projecting means that project the signal light , with respect to the light receiving means installed facing the light projecting means, The signal light can be projected by the light projecting means .

  The dimming sensor according to claim 2 is the dimming sensor according to claim 1, wherein all of the light projecting means set to project the signal light by the setting means. Are connected in series with each other.

  Further, the dimming sensor according to claim 3 is the dimming sensor according to claim 1, wherein the light projecting unit is set to project the signal light by the setting unit. The parts are connected in parallel.

  According to a fourth aspect of the present invention, the dimming sensor according to the first aspect of the present invention is the dimming sensor according to the first aspect, wherein the setting means is configured to project the signal light. The units are connected in series to each other to form a plurality of systems, and the plurality of systems are further connected in parallel.

The dimming sensor according to claim 5 is the dimming sensor according to any one of claims 1 to 4, further comprising control means for controlling the operation of the setting means, wherein the control The means is characterized in that the setting means sets the number of the light projecting means for projecting the signal light based on the information output from the light receiving means.
Further, the light-reducing sensor according to claim 6 is the light-reducing sensor according to any one of claims 1 to 5, wherein the signal light is received by one light receiving means. It is characterized by comprising four light projecting means for projecting light.
A dimming sensor according to claim 7 is the dimming sensor according to claim 6, wherein the light projecting direction of the signal light by each light projecting means and the light receiving by the light receiving means. In order to match the direction, each of the four light projecting units is arranged so that the light projecting axis of each light projecting unit is substantially parallel to the light receiving axis of the light receiving unit. .

  According to the first aspect of the present invention, the signal light simultaneously projected from each of the plurality of light projecting units is applied to the light receiving unit in an overlapping manner. Therefore, the optical power density of the signal light at the light receiving means can be increased in proportion to the number of light projecting means, and the S / N ratio can be greatly improved. In addition, since the size of each light projecting means is the same as or smaller than the light projecting means in the conventional light-reducing sensor, the depth dimension of the light-reducing sensor is equal to or smaller than that of the conventional light-reducing sensor. be able to. Further, not only the adjustment of the light emission current of the light projecting means, but also the signal light projected from the light projecting means can be adjusted by changing the drive number of the light projecting means by the setting means. On the other hand, signal light having an appropriate intensity can be irradiated. This makes it possible to adjust the light power density of the signal light widely and finely according to the installation conditions of the dimming sensor.

  According to the second aspect of the present invention, even when a plurality of light projecting means are driven, an increase in current consumption can be prevented and power loss can be reduced.

  According to the third aspect of the present invention, even when the power supply voltage is limited, the current consumption can be reduced and the power loss can be reduced within the range of the limitation.

  According to the fourth aspect of the present invention, the effects of both the second and third aspects can be obtained.

  According to the fifth aspect of the present invention, the setting unit is controlled by the control unit, and the number of the light projecting units to be driven can be switched based on the information output from the light receiving unit. Thereby, according to the installation conditions of the light-reducing sensor, signal light having an appropriate intensity can reach the light receiving means.

  Embodiments of the dimming sensor according to the present invention will be described below in detail with reference to the accompanying drawings. [I] First, the basic concept of each embodiment will be described, then [II] the specific contents of each embodiment will be described, and [III] Finally, modifications to each embodiment will be described. However, the present invention is not limited to each embodiment.

[I] Basic concept of each embodiment First, a basic concept common to each embodiment will be described. The dimming sensor according to each embodiment is intended to detect smoke generated with a fire.

  The dimming sensor according to each embodiment can be installed arbitrarily, for example, in a large-scale building such as a factory facility or a building, an underground shopping center, or a room such as a kitchen or bedroom in a general house. be able to.

  One of the features of the dimming sensor according to each embodiment is that it includes a plurality of light projecting units that project the signal light so that the light can be received by one light receiving unit. It is in. When a plurality of light projecting means are driven, the signal light projected from the driven light projecting means is simultaneously irradiated so as to be superimposed on one light receiving means. Therefore, since the optical power density of the signal light at the light receiving means is improved in proportion to the number of light projecting means installed for one light receiving means, the S / N ratio is greatly improved. Can do.

[II] Specific Contents of Each Embodiment Next, specific contents of each embodiment according to the present invention will be described.

[Embodiment 1]
First, the first embodiment will be described. This form includes four light projecting means for projecting signal light so that light can be received by one light receiving means, an amplifier means and an amplification degree control means, and further includes a setting means. It is. In the first embodiment, a dimming reflection type sensor will be described as an example, but the same configuration can be applied to a dimming type separation sensor.

(Configuration of dimming sensor)
First, the configuration of the dimming sensor will be described. 1 is a perspective view of a dimming sensor according to Embodiment 1, FIG. 2 is an exploded view of the dimming sensor, and FIG. 3 is a block diagram functionally conceptually showing the electrical configuration of the dimming sensor. FIG. 4 is a front view of the dimming sensor with the cover and lens cover removed.

  As shown in FIG. 1, the dimming sensor 1 is disposed to face the reflector 2 in a region to be monitored for smoke generation. The dimming sensor 1 receives the signal light projected from the dimming sensor 1 and reflected by the reflecting plate 2, and monitors the amount of light received. Further, as shown in FIGS. 2 and 3, the dimming sensor 1 has a housing 10 serving as a basic structure. The housing 10 includes a housing body 10a and a housing body 10a. The cover 10b is detachably attached to the cover 10b. Further, the optical unit 20, the display unit 30, the storage unit 40, the control unit 50, and the changeover switch 60 are mounted on the housing body 10a.

(Configuration of dimming sensor-optical unit)
The optical unit 20 is a unit in which optical devices used to detect smoke in the light-reducing sensor 1 are integrated into one unit. For example, the light projecting unit 21, the light receiving unit 22, the sighting unit 23, and the lens A cover 24 is provided.

  The light projecting unit 21 is for projecting signal light used for detecting smoke to the reflecting plate 2, and corresponds to the light projecting means in the claims. Specifically, as shown in FIG. 4, in the first embodiment, as the light projecting unit 21, a first light projecting unit 21a, a second light projecting unit 21b, a third light projecting unit 21c, A total of four light projecting units 21 of the fourth light projecting unit 21 d are installed in the optical unit 20. The size of each light projecting unit 21 is equal to or smaller than that of the light projecting unit in the conventional dimming sensor 1. Moreover, it is desirable that the configuration of each light projecting unit 21 is the same. The specific configuration of the light projecting unit 21, the wavelength of the light projected from the light projecting unit 21, and the like are arbitrary. For example, an LED (Light Emitting Diode) 210 that emits near infrared light is used as a light source, and the LED 210 The light emitted from the lens may be condensed by the lens 211 and projected.

  The light receiving part 22 is for receiving the signal light reflected by the reflecting plate 2, and corresponds to the light receiving means in the claims. Although the specific configuration of the light receiving unit 22 is arbitrary, for example, a lens 220 that collects signal light incident on the light receiving unit 22, a photodiode that converts the signal light collected by the lens 220 into an electrical signal, or the like A light receiving element 221 and an amplifying unit 222 that amplifies an electric signal output from the light receiving element 221 and outputs the amplified signal as a light receiving signal to the control unit 50 are provided. The amplifying unit 222 corresponds to the amplifying means in the claims. The amplification unit 222 is controlled by the amplification degree control unit 53 described later, and switches the amplification degree for the electric signal output from the light receiving element 221 in a stepwise manner. The specific configuration of the amplifying unit 222 is arbitrary. For example, the amplification degree by the amplifying unit 222 can be switched stepwise by connecting a plurality of amplifier circuits in combination and switching the amplifying circuit to be operated. .

  Returning to FIG. 3, the sighting device 23 is dimmed so that the reflector 2 is positioned within the irradiation area of the signal light projected from the light projecting unit 21 when the dimming sensor 1 is installed. It is used to determine the installation direction of the type sensor 1. The specific configuration of the sighting device 23 is arbitrary. For example, the sighting hole 230 having a shape similar to the shape of the signal light irradiation region and the viewing hole 231 are provided on the lens cover 24, and the mirror 232 is provided on the optical unit 20. You may make it visually recognize the reflector 2 located in the aiming hole 230 through the mirror 232 from the viewing hole 231. When looking through the sighting hole 230 reflected on the mirror 232 from the sighting hole 231, the installation angle of the light-reducing sensor 1 is adjusted so that the reflector 2 is positioned at the center of the sighting hole 230. The reflecting plate 2 can be irradiated with signal light projected from the light unit 21. In FIG. 2, the viewing hole 231 is formed with an angle and a size with respect to the plate thickness direction so that the aiming hole 230 can be seen through the mirror 232 in a state where the lens cover 24 is attached to the housing body 10 a.

  The lens cover 24 is for covering the lenses of the light projecting unit 21 and the light receiving unit 22, and is disposed in front of the lenses of the light projecting unit 21 and the light receiving unit 22.

  The light projecting unit 21, the light receiving unit 22, and the sighting device 23 are fixed on the optical unit 20 so as to be close to each other. Further, the light projecting unit 21 and the light receiving unit 22 are arranged with their optical axes parallel to each other so that the light projecting direction of the light projecting unit 21 and the light receiving direction of the light receiving unit 22 coincide. Further, although the arrangement of the light projecting units 21 is arbitrary, it is desirable that the light projecting axes of the light projecting units 21 are arranged on the same circumference around the light receiving axis of the light receiving unit 22. That is, it is desirable that the light projecting units 21 are arranged at the same interval as the light receiving unit. Furthermore, it is desirable that the light projecting portions 21 arranged in this way are arranged at the same interval.

(Configuration of dimming sensor-display section)
The display unit 30 is for displaying an operation state (for example, a monitoring state, a failure state, a fire state, etc.) of the dimming sensor 1, and is controlled by the control unit 50. The specific configuration of the display unit 30 is arbitrary, and a plurality of LEDs that emit light in colors corresponding to each state (for example, monitoring state: green, fault state: yellow, fire state: red) may be used, or Alternatively, characters may be displayed using a liquid crystal display device. In addition, as the above-described operation state, it is possible to display the number of driving of the light projecting unit 21, the amount of light received by the light receiving unit 22, the received light amplification degree, or various guidance displays.

(Configuration of dimming sensor-storage unit)
The storage unit 40 stores information used for processing in the light-reducing sensor 1, for example, a history of received light intensity at the light receiving unit 22, a history of internal correction related to optical member contamination compensation, and the like. It is.

(Configuration of dimming sensor-control unit)
The control unit 50 is for performing predetermined processing in the dimming sensor 1. As shown in FIG. 3, the control unit 50 includes a light projection control unit 51, a light reception control unit 52, an amplification degree control unit 53, and a fire determination unit 54.

  The light projection control unit 51 is for controlling the light projection unit 21, and corresponds to the control means in the claims. Specifically, timing for driving a light source such as the LED 210 in the light projecting unit 21, control of a light emission current supplied to the light projecting unit 21, control of a changeover switch 60 described later, and the like are performed.

  The light receiving control unit 52 is for controlling the light receiving unit 22, and specifically, the timing at which the light receiving element 221 of the light receiving unit 22 performs light reception or the timing at which the received signal light is sampled. Then, the electrical signal converted by the light receiving element 221 is processed.

  The amplification degree control unit 53 is for controlling the amplification degree of the electric signal output from the light receiving element 221 by the amplification unit 222, and corresponds to the amplification degree control means in the claims. The amplification degree control unit 53 adjusts the input level of the received light signal input from the light receiving unit 22 to the control unit 50 within a predetermined range by controlling the amplification degree by the amplification unit 222.

  The fire determination unit 54 determines a fire or the like based on a signal input from the light receiving unit 22 that has received the signal light via the light reception control unit 52, and corresponds to the abnormality determination unit in the claims. ing.

  The specific configuration of the control unit 50 is arbitrary. For example, a control program such as an OS (Operating System), an embedded program that defines various processing procedures, an internal memory for storing required data, and A CPU (Central Processing Unit) that executes these programs is provided.

(Configuration of dimming sensor-changeover switch)
The changeover switch 60 is for setting the number of light projecting units 21 to be driven, and corresponds to setting means in the claims. The specific configuration of the changeover switch 60 is arbitrary. For example, the changeover switch 60 is incorporated in an electric circuit connecting the control unit 50 and the light projecting unit 21, and based on an input from the light receiving unit 22 to the control unit 50. Thus, the changeover switch 60 can be controlled by the light projection control unit 51. Alternatively, by using a dip switch or the like as the changeover switch 60, the number of light projecting units 21 to be driven can be changed manually.

(Structure of reflector)
The reflecting plate 2 is for reflecting the signal light projected from the light projecting unit 21, and corresponds to the reflecting means in the claims. The reflection plate 2 is disposed so as to face the light projection direction of the signal light, and so that the light projection direction and the surface of the reflection plate 2 are substantially orthogonal. Although the specific structure of the reflecting plate 2 is arbitrary, it is desirable to use a retroreflecting plate that reflects incident light in the incident direction. Thus, when the signal light is irradiated from the optical unit 20 to the reflection plate 2, the signal light is reliably reflected by the reflection plate 2 toward the optical unit 20 and is received in the vicinity of the light projecting unit 21. The unit 22 can receive light.

(Operation of dimming sensor)
Next, the operation of the dimming sensor 1 will be described. FIG. 5 is a plan view conceptually showing the irradiation distribution of the signal light reflected by the reflecting plate 2 and irradiated on the light receiving unit 22.

  The signal light projected from the four light projecting units 21 arranged around the light receiving unit 22 is reflected by the retroreflecting plate toward the light projecting unit 21 on which each signal light is projected. The As shown in FIG. 5, the signal light traveling from the light projecting unit 21 to the reflecting plate 2 includes a first light projecting unit 21 a, a second light projecting unit 21 b, and a third light projecting unit arranged around the light receiving unit 22. The light distribution is indicated by A, B, C, and D centered on the optical axis of each of the light projecting units 21 at a certain propagation distance, which is projected from the light unit 21c and the fourth light projecting unit 21d. ing. Here, as described above, since the configurations such as the output and size of the light projecting units 21 are the same, the irradiation distributions A, B, C, and D of the signal light irradiated simultaneously have the same size. It has a substantially circular area. Moreover, since the distance of each light projection part 21 and the light-receiving part 22 is the same, and each light-projection part 21 is arrange | positioned mutually spaced apart, irradiation distribution A, B, C, D is light reception. The portions 22 are uniformly overlapped with each other. Thus, the substantially central portion of the overlapping irradiation distribution is irradiated onto the reflecting plate 2, and the reflected light from the reflecting plate 2 enters the light receiving unit 22 disposed close to the light projecting unit 21.

  FIG. 6 is a graph showing the intensity distribution of signal light in the E-E ′ cross section of FIG. 5. As shown in FIG. 6, the signal lights simultaneously projected from the first light projecting unit 21a, the second light projecting unit 21b, the third light projecting unit 21c, and the fourth light projecting unit 21d are It has a mountain-shaped intensity distribution having a peak in the vicinity of the light projecting portion 21 where the signal light is projected, and overlaps in the vicinity of the reflector 2. As shown in FIG. 6, the intensity of the signal light that is simultaneously projected from each light projecting unit 21 and reaches the reflecting plate 2 is the result of the overlapping of the signal light projected from each light projecting unit 21. The intensity of light received is approximately four times the received light intensity.

(Operation of dimming sensor-initial adjustment process)
Next, when the dimming sensor 1 is installed, in order to adjust the output at the light projecting unit 21, the number of drives of the light projecting unit 21, and the amplification degree at the light receiving unit 22 according to the installation conditions. The initial adjustment process flow will be described. Specifically, the control unit 50 executes control of the light emission current supplied to the light projecting unit 21, drive number switching processing of the light projecting unit 21, control of the amplification degree in the amplification unit 222, and the like. In the above description, it is described that the changeover switch 60 can be manually operated. However, a case where the changeover switch 60 is controlled by the control unit 50 will be described below.

  First, an outline of the initial adjustment process will be described. FIG. 7 is a flowchart showing a schematic flow of the initial adjustment process. After the optical axes of the light projecting unit 21 and the light receiving unit 22 are mechanically adjusted and fixed using the sighting device 23, the dimming sensor 1 is activated by a predetermined activation operation, or initial setting is started. When an operation of a switch or the like is performed, as shown in FIG. 7, the light projection control unit 51 controls the changeover switch 60 so that only the first light projection unit 21a can be driven (step SA-1). Subsequently, the light projection control unit 51 energizes the first light projecting unit 21a with a predetermined light emission current as an initial light emission current, and drives the first light projecting unit 21a (step SA-2). When the signal light projected from the first light projecting unit 21 a is reflected by the reflecting plate 2 and received by the light receiving unit 22, a light reception signal corresponding to the light reception intensity of the signal light at the light receiving unit 22 is received by the control unit 50. Is input. When the level of the light reception signal at this time is within a predetermined range (step SA-3, Yes), the amplification degree control unit 53 fixes the amplification degree, and the light projection control unit 51 executes the light emission current adjustment process. (Step SA-4). If the level of the received light signal is out of the predetermined range (step SA-3, No), the amplification degree control / drive number switching process is executed by the amplification degree control unit 53 and the light projection control unit 51 ( Step SA-5), it is judged again whether or not the level of the received light signal is within a predetermined range (Step SA-3).

(Operation of dimming sensor-Light emission current adjustment processing)
Next, the light emission current adjustment process in step SA-4 will be described. FIG. 8 is a flowchart showing the flow of light emission current adjustment processing. As shown in FIG. 8, the amplification degree control unit 53 maintains the amplification degree by the amplification unit 222 at the time when the light emission current adjustment processing is started (step SB-1). When the level of the received light signal matches the predetermined value within the tolerance range (step SB-2, Yes), the light projecting control unit 51 is the level of the light emission current that is energized to each light projecting unit 21. Is maintained (step SB-3). When the level of the received light signal is out of the tolerance range (step SB-2, No), the light projection control unit 51 changes the light emission current to be supplied to each light projecting unit 21, and the level of the received light signal is Adjustment is made so as to match the predetermined value within the range of tolerance (step SB-4).

(Density sensor operation-amplification adjustment and drive number switching)
Next, the amplification degree adjustment / drive number switching process in step SA-5 will be described. FIG. 9 is a flowchart showing the flow of the amplification degree adjustment / drive number switching process. As shown in FIG. 9, when the level of the received light signal exceeds the predetermined range (step SC-1, Yes), the amplification degree control unit 53 determines whether or not the amplification degree in the amplification unit 222 is at the minimum stage. Confirm (step SC-2). When the amplification degree is not at the minimum stage (step SC-2, No), the amplification degree control unit 53 reduces the amplification degree by the amplification part 222 by one stage (step SC-3). If the amplification level is at the minimum level (step SC-2, Yes), the amplification level control unit 53 determines that the level of the received light signal is saturated due to an optical axis shift, disturbance light incidence, or the like, and an error occurs. And an error display on the display unit 30 (step SC-4), and the initial adjustment process is terminated.

  On the other hand, when the level of the received light signal is below the predetermined range (step SC-1, No), the amplification degree control unit 53 checks whether or not the amplification degree in the amplification unit 222 is at the maximum level (step SC). -5). If the amplification level is not at the maximum level (No at Step SC-5), the amplification level control unit 53 increases the amplification level by the amplification unit 222 by one level (Step SC-6). When the amplification degree by the amplifying unit 222 is at the maximum stage (step SC-5, Yes), the light projecting control unit 51 confirms whether the driving number of the light projecting unit 21 is maximum (step SC-7). When the driving number of the light projecting unit 21 is not the maximum (step SC-7, No), the light projecting control unit 51 increases the driving number of the light projecting unit 21 by one (step SC-8), and controls the amplification degree. The unit 53 resets the amplification degree by the amplification unit 222 to the initial value (step SC-9). When the drive number of the light projecting unit 21 is the maximum (step SC-7, Yes), the light projecting control unit 51 determines that the level of the received light signal is insufficient due to an optical axis shift or the like, which means an error. While outputting a signal, the display unit 30 displays an error (step SC-10), and the initial adjustment process is terminated.

(Effect of Embodiment 1)
As described above, according to the first embodiment, the dimming sensor 1 includes the plurality of light projecting units 21 with respect to one light receiving unit 22, and the signal light simultaneously projected from each light projecting unit 21. Are applied to the reflector 2 in an overlapping manner. Therefore, the optical power density of the signal light reflected by the reflecting plate 2 and reaching the light receiving unit 22 can be increased in proportion to the number of the light projecting units 21, and the S / N ratio can be greatly improved. In addition, since the size of each light projecting unit 21 is the same as or smaller than the light projecting unit in the conventional light-reducing sensor, the depth dimension of the light-reducing sensor 1 is equal to that of the conventional light-reducing sensor, or Can be small.

  Further, the drive number of the light projecting unit 21 can be switched by the changeover switch 60. Therefore, not only the adjustment of the light emission current of the light projecting unit 21 but also the signal light emission energy to be projected from the light projecting unit 21 can be adjusted by the number of driving of the light projecting unit 21. An appropriate intensity of signal light can be irradiated. As a result, a wide and fine adjustment of the signal light emission energy corresponding to the installation conditions of the dimming sensor 1 (for example, the distance between the light projecting portion 21 and the reflecting plate 2 in the dimming reflection type sensor, etc.) is possible. It becomes possible.

  Further, since the changeover switch 60 is controlled by the light projection control unit 51, the number of the light projecting units 21 to be driven can be switched based on the input from the light receiving unit 22 to the control unit 50. As a result, signal light having an appropriate intensity can reach the light receiving unit 22 in accordance with the installation conditions of the dimming sensor 1.

  The light projecting unit 21 and the light receiving unit 22 are arranged close to each other, and the light projecting direction of the light projecting unit 21 and the light receiving direction of the light receiving unit 22 are aligned with each other. Since the reflecting plate 2 is disposed so as to face the light projecting direction, the signal light reflected from the reflecting plate 2 is received by projecting the signal light from the light projecting unit 21 toward the reflecting plate 2. 22 can receive light.

  Further, since the dimming sensor 1 includes four light projecting units 21 with respect to one light receiving unit 22, the light power density of the signal light in the light receiving unit 22 is calculated when the number of the light projecting units 21 is one. Can be increased by a factor of about 4, and the S / N ratio can be greatly improved.

  In addition, since the distance between each light projecting unit 21 and the light receiving unit 22 is the same, and each light projecting unit 21 is arranged at the same interval from each other, the light is projected from each light projecting unit 21 and the reflecting plate. 2 can be uniformly overlapped with each other around the light receiving axis of the light receiving unit 22 (substantially the center of the reflecting plate 2), and is reflected by the reflecting plate 2 and received by the light receiving unit 22. The optical power density of light can be remarkably improved.

  In addition, since the amplification unit 222 is controlled by the amplification degree control unit 53 and the amplification degree for the electric signal output from the light receiving element 221 is adjusted, the intensity of the light intensity sensor corresponding to the installation condition of the dimming sensor 1 is adjusted. Based on the received light signal, the control unit 50 can perform processing such as fire determination.

[Embodiment 2]
Next, a second embodiment will be described. This form is the form which connected the light projection means combining the serial connection and the parallel connection. In the following description, a changeover switch as a setting means for setting the number of driving of the light projecting means is specifically shown.

(Circuit configuration of the light projecting unit 21)
First, the circuit configuration of the light projecting unit 21 will be described. FIG. 10 is a circuit diagram showing an outline of a drive circuit in the light projecting unit 21 according to the second embodiment. FIG. 10A shows a case where all four light projecting units 21 are connected in series. b) is a diagram illustrating a case in which four light projecting units 21 are connected in combination of series connection and parallel connection. The configuration of the second embodiment is substantially the same as the configuration of the first embodiment except where otherwise specified, and the same configuration as that of the first embodiment is used in the first embodiment. The same reference numerals and / or names are attached as necessary, and the description thereof is omitted.

  As described above, since the light-reducing sensor 1 according to the present invention includes the plurality of light projecting units 21, depending on the circuit configuration, the current consumption increases greatly as the number of driving of the light projecting units 21 increases. The power loss may increase. On the other hand, in order to suppress the current consumption value, it is desirable to connect all the light projecting units 21 in series as shown in FIG. In FIG. 10A, the dimming sensor 1 includes a single drive circuit in which four light projecting units 21 are connected in series. Moreover, the changeover switch 60 is provided so that each light projection part 21 may be bypassed, and the drive number of the light projection part 21 can be arbitrarily switched by combining ON / OFF of these changeover switches 60.

  As described above, in order to reduce current consumption, it is desirable to connect all the light projecting units 21 in series, but the driving voltage when all the light projecting units 21 are driven is applied to the light projecting unit 21. In some cases, it may exceed the voltage of the power supply that supplies power. In such a case, as shown in FIG. 10B, it is also possible to configure a circuit in which a plurality of sets (two systems in this case) of drive circuits in which two light projecting units 21 are connected in series are connected in parallel. . In addition, this circuit includes a changeover switch 60 that bypasses the light projecting unit 21 and a changeover switch 60 that connects two circuits in parallel, and the light is projected by combining ON / OFF of these changeover switches 60. The drive number of the unit 21 can be arbitrarily switched.

(Effect of Embodiment 2)
Thus, according to the second embodiment, since all the light projecting units 21 are connected in series, in addition to the basic effect in the first embodiment, even when a plurality of light projecting units 21 are driven. An increase in current consumption can be prevented and power loss can be reduced.

  In addition, by connecting the light projecting unit 21 by combining serial connection and parallel connection, even when the power supply voltage is limited, current consumption can be reduced and power loss can be reduced within the range of the limitation. it can.

  In addition, since the changeover switch 60 that bypasses the light projecting unit 21 and the changeover switch 60 that connects the two systems of drive circuits in parallel are combined, the light projection to be driven corresponding to the installation conditions of the dimming sensor 1 is combined. The number of light parts 21 can be changed finely.

[III] Modifications to Each Embodiment While each embodiment according to the present invention has been described above, the specific configuration and means of the present invention are the same as the technical idea of each invention described in the claims. Modifications and improvements can be arbitrarily made within the range. Hereinafter, such a modification will be described.

(About problems to be solved and effects of the invention)
First, the problems to be solved by the invention and the effects of the invention are not limited to the above-described contents, and the present invention solves the problems not described above or has the effects not described above. There are also cases where only some of the described problems are solved or only some of the described effects are achieved. For example, even if the desired S / N ratio cannot be obtained unless the depth of the dimming sensor is increased, the S / N ratio can be slightly improved by applying the present invention. As long as the problem of this application is solved.

(About dimming type separate sensor)
In each of the above-described embodiments, the dimming reflection type sensor has been described as an example, but the same configuration can be applied to the dimming type separation type sensor. The dimming separation type sensor includes a light projecting unit that projects signal light, and a light receiving unit that is disposed opposite to the light projecting unit and receives signal light, and is sandwiched between the light projecting unit and the light receiving unit. The monitored area is the monitoring area. In this dimming separation type sensor, as in the case of the dimming reflection type sensor, by providing a plurality of light projecting units for one light receiving unit, the optical power density of the signal light at the light receiving unit Can be increased in proportion to the number of light projecting units, and the S / N ratio can be greatly improved. In addition, by arranging the light projecting units on the same circumference with the optical axis of the light receiving unit as the center, and arranging them at the same interval from each other, they are simultaneously projected and received by each light projecting unit. The signal light applied to the light receiving portion can be uniformly overlapped with each other around the light receiving portion, and the optical power density of the signal light at the light receiving portion can be significantly improved.

(About changeover switch 60)
In Embodiment 1, although the case where the changeover switch 60 was controlled by the control part 50 was demonstrated, you may make it change the changeover switch 60 by manual operation. In this case, when the dimming sensor 1 is installed, first, after determining the number of drives of the light projecting unit 21 by switching the changeover switch 60 according to the monitoring distance of the dimming sensor 1, The amplification degree by the amplification unit 222 can be adjusted so that the level of the light reception signal output from the light reception unit 22 is within a predetermined range.

  The dimming smoke detector according to the present invention detects the attenuation of light that has been projected from the light projecting means, passed through the space that is the monitoring area and reached the light receiving means, and senses the presence of smoke due to a fire or the like. In particular, the optical power density of the signal light projected from the light projecting unit can be efficiently improved without increasing the depth dimension of the dimming sensor, and the S / N This is useful for dimming detectors with significantly improved ratios. This smoke sensor can be applied not only to a reflection type smoke sensor but also to a separate type smoke sensor.

FIG. 3 is a perspective view of the dimming sensor according to Embodiment 1. It is an exploded view of a dimming sensor. FIG. 3 is a block diagram functionally conceptually showing an electrical configuration of a dimming sensor. It is a front view of a light-reducing sensor with the cover removed. It is the top view which showed notionally the irradiation distribution of the signal light in a certain propagation distance. 6 is a graph showing the intensity distribution of signal light in the E-E ′ cross section of the irradiation distribution shown in FIG. 5. It is the flowchart which showed the general flow of the initial adjustment process. It is the flowchart which showed the flow of the light emission current adjustment process. It is the flowchart which showed the flow of amplification degree adjustment and the drive number switching process. FIG. 10A is a circuit diagram illustrating an outline of a drive circuit in the light projecting unit 21 according to the second embodiment. FIG. 10A illustrates a case where all four light projecting units 21 are connected in series, and FIG. It is a figure which shows the case where the four light projection parts 21 are connected combining the serial connection and the parallel connection.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Dimming type sensor 2 Reflector 10 Case 10a Case main body 10b Cover 20 Optical unit 21 Light projection part 21a 1st light emission part 21b 2nd light emission part 21c 3rd light emission part 21d 4th Light emitting unit 22 Light receiving unit 23 Aiming device 24 Lens cover 30 Display unit 40 Storage unit 50 Control unit 51 Light projection control unit 52 Light reception control unit 53 Amplification degree control unit 54 Fire determination unit 60 Changeover switch 210 LED
211 Lens 220 Lens 221 Light receiving element 222 Amplifying unit 230 Aiming hole 231 Viewing hole 232 Mirror

Claims (7)

A light-reducing method in which the signal light projected from the light projecting unit to the monitoring region is received by the light receiving unit, and the presence or absence of a predetermined monitoring target in the monitoring region is determined based on the information output from the light receiving unit A sensor,
A plurality of the light projecting means for projecting the signal light so as to be received by one light receiving means;
Setting means for setting the number of the light projecting means for projecting the signal light,
The signal light can be projected by the light projecting unit with respect to the light receiving unit installed facing the light projecting unit,
This is a dimming sensor. All of the light projecting means set to project the signal light by the setting means are connected to each other in series;
The light-reducing sensor according to claim 1. A part of the light projecting unit set to project the signal light by the setting unit is connected in parallel;
The light-reducing sensor according to claim 1. A part of the light projecting means set to project the signal light by the setting means is connected in series to form a plurality of systems, and the plurality of systems are further connected in parallel;
The light-reducing sensor according to claim 1. Control means for controlling the operation of the setting means,
The control unit causes the setting unit to set the number of the light projecting units that project the signal light based on the information output from the light receiving unit;
The light-reducing sensor according to any one of claims 1 to 4, wherein: For projecting the signal light so as to be received by one of said light receiving means, it comprises four of said light projecting means,
The light-reducing sensor according to claim 1, wherein: In order to make the light projecting direction of the signal light by each light projecting means coincide with the light receiving direction of the signal light by the light receiving means, the light projecting axis of each light projecting means is substantially parallel to the light receiving axis of the light receiving means. Arranging each of the four light projecting means so that
The light-reducing sensor according to claim 6.

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