JPH11160238A - Photoelectric smoke sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable photoelectric smoke sensor which can sense smoke accurately irrespective of a sensitivity difference between white smoke and black smoke. SOLUTION: A photoelectric smoke sensor 1 has a light projection part 6 projecting light to a smoke sensing area 8 and photodetecting parts 7a, 7b detecting a scattering light by a smoke present at the smoke sensing area 8. The sensor is provided with a plurality of the light projection parts 6 or photodetecting parts 7a, 7b so that a plurality of angles are obtained between a projection axis and a photodetecting axis. Moreover, the sensing device is adapted to distinguish from a plurality of intensities of light obtained by the photodetecting parts 7a, 7b whether the smoke present at the smoke sense area is a white smoke or black smoke.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric smoke detector for detecting the occurrence of a fire from the scattered light of smoke generated at the time of a fire.

[0002]

2. Description of the Related Art FIG. 12 is an external view of a conventional photoelectric smoke detector, and FIG. 13 is a sectional view taken along line XX of FIG. The photoelectric smoke detector 1 includes a body 2 and a smoke detector 3, and includes a processing unit (not shown) using an electric circuit and a dark box 4 for detecting smoke. In addition, a fine mesh is attached to the outer periphery of the smoke sensing unit 3 to prevent insects, large dust and the like from entering the inside (dark box 4).

The surroundings of the dark box 4 are surrounded by a labyrinth 5 which blocks external light but introduces smoke. Also,
Around the dark box 4, a light emitting unit 6 such as a light emitting diode and a light receiving unit 7 such as a photodiode provided with a light receiving axis shifted from the light emitting axis of the light emitting unit 6 are provided. A smoke sensing area 8 is formed near the intersection of the light emitting axis and the light receiving axis. When the light emitted from the light emitting unit 6 is irregularly reflected on the smoke flowing into the smoke sensing area 8 in the dark box 4 and is received by the light receiving unit 7, the light receiving unit 7 outputs a small current, Thereby, smoke is sensed. Therefore, in the conventional photoelectric smoke detector, the current obtained from the light receiving unit 7 is used as it is regardless of the type of smoke.

[0004]

However, in the photoelectric smoke sensor having the above-described structure, the output of black smoke is smaller than the output of white smoke when the density of the smoke is reduced. And there is a problem that a difference in sensitivity occurs depending on the type of smoke.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a highly reliable photoelectric system capable of accurately detecting smoke regardless of the sensitivity difference between white smoke and black smoke. It is to provide a smoke detector.

[0006]

According to the first aspect of the present invention,
In a photoelectric smoke sensor having a light projecting unit that irradiates light to a smoke sensing area and a light receiving unit that receives light scattered by smoke existing in the smoke sensing area, the angle between the light projecting axis and the light receiving axis is plural. A plurality of light emitting units or light receiving units are provided so as to be formed, and a determination unit for identifying whether the smoke present in the smoke sensing area is white smoke or black smoke based on a plurality of light receiving intensities obtained by the light receiving unit. It is characterized by being added.

According to a second aspect of the present invention, in the photoelectric smoke sensor according to the first aspect, an output adjustment unit for adjusting an output or a warning level from the photoelectric smoke sensor based on a result of the determination unit is added. It is characterized by having done.

According to a third aspect of the present invention, there is provided the photoelectric smoke detector according to the first or second aspect, further comprising a light projecting unit, a first light receiving unit, and a second light receiving unit. The judgment unit discriminates between white smoke and black smoke by comparing the ratio of the received light intensity detected by the light receiving unit of the second light receiving unit and the received light intensity detected by the second light receiving unit with a predetermined value set in advance. It is characterized by the following.

According to a fourth aspect of the present invention, there is provided the photoelectric smoke detector according to the first or second aspect, further comprising a light projecting unit, a first light receiving unit, and a second light receiving unit. The received light intensity detected by the first light receiving unit and the detection of the second light receiving unit are set such that the received light intensity detected by the first light receiving unit is equal to the received light intensity detected by the second light receiving unit at the set reference value. The received light intensity is corrected, and the corrected values are compared to discriminate between white smoke and black smoke in the determination unit.

According to a fifth aspect of the present invention, in the photoelectric smoke detector according to the third or fourth aspect, an angle formed between the light projecting portion and the first light receiving portion around the center of the smoke sensing region. To 11
The angle is between 0 ° and 130 °, and the angle between the light projecting section and the second light receiving section is between 50 ° and 70 °.

According to a sixth aspect of the present invention, in the photoelectric smoke detector according to the first or second aspect, the first light projecting unit includes
A first light projecting unit, a light receiving unit, and a switching unit that switches light emission timings of the first light projecting unit and the second light projecting unit;
By comparing the ratio of the received light intensity of the scattered light by the light emitting unit and the received light intensity of the scattered light by the second light emitting unit with a predetermined value set in advance, the determination unit identifies white smoke or black smoke. It is characterized by doing so.

According to a seventh aspect of the present invention, there is provided the photoelectric smoke detector according to the first or second aspect, wherein the first light projecting section includes:
A second light projecting section, a light receiving section, and a switching section for switching light emission timings of the first light projecting section and the second light projecting section, wherein the first light projecting section is operated at a preset reference value. The received light intensity detected by the second light projecting unit is equal to the received light intensity detected by the second light emitting unit.
The received light intensity emitted by the first light emitting unit and the received light intensity emitted by the second light emitting unit are corrected, and the corrected values are compared to determine whether the smoke is white smoke or black smoke. It is characterized in that it is identified.

According to an eighth aspect of the present invention, in the photoelectric smoke detector according to the sixth or seventh aspect, an angle formed between the light receiving portion and the first light projecting portion around the center of the smoke sensing region. To 11
0 ° to 130 °, and the angle formed between the light receiving section and the second light projecting section is set to 50 ° to 70 °.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to FIGS. 12 and 13 described in the related art are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIGS. 1A and 1B show a photoelectric smoke detector according to a first embodiment, wherein FIG. 1A is an external view and FIG. 1B is a sectional view taken along line XX. FIG. 2 is an XX cross-sectional view of another photoelectric smoke detector according to the first embodiment. FIG. 3 is a schematic configuration diagram of the photoelectric smoke detector according to the first embodiment. FIG. 4 is a diagram showing the relationship between the scattered light intensity of 120 ° and the scattered light intensity of 60 ° in white smoke and black smoke. FIG. 5 is a schematic configuration diagram of another photoelectric smoke detector according to the first embodiment. Figure 6
It is a figure which shows the relationship between 120 degree scattered light intensity and 60 degree scattered light intensity in white smoke and black smoke when GAIN adjustment is performed. FIG. 7 shows X of the photoelectric smoke detector according to the second embodiment.
It is -X sectional drawing. FIG. 8 is a schematic configuration diagram of a photoelectric smoke detector according to the second embodiment. FIG. 9 is an XX cross-sectional view of an experimental device having a shape equivalent to a photoelectric smoke detector used for finding an appropriate angle. FIG. 10 is a diagram showing the relationship between the ratio of the two received light intensities due to white smoke and the ratio of the two received light intensities due to black smoke to the combination of the scattering angles. FIG.
FIG. 3 is a diagram showing a definition of an angle of an optical system of a photoelectric smoke detector.

[First Embodiment] As shown in FIG.
The photoelectric smoke detector 1 includes a light emitting unit 6 including a light emitting diode or the like provided in a dark box 4 and light receiving units 7a and 7 including a photodiode or the like provided with a light receiving axis shifted from the optical axis of the light emitting unit 6.
b, and the angles formed by the light projecting axis of the light projecting unit 6 and the light receiving axes of the two light receiving units 7a and 7b are different from each other. That is, for example, the angle A formed between the light emitting axis of the light projecting unit 6 and the light receiving axis of the first light receiving unit 7a is 120 °, and the light emitting axis of the light projecting unit 6 and the light receiving axis of the second light receiving unit 7b are set. Angle B with
Is set to 60 °. The angle A is about 110 ° to 130 °.
° and the angle B are desirably between 50 ° and 70 °, but are not limited thereto.

In the photoelectric smoke detector 1 having the above configuration,
The light receiving intensity of the first light receiving portion 7a and the light receiving intensity of the second light receiving portion 7b in white smoke (cotton wick brick smoke) and black smoke (kerosene combustion smoke) have a relationship as shown in FIG. I have. That is,
When the light receiving intensity of the first light receiving unit 7a is constant, black smoke shows higher light receiving intensity in the second light receiving unit 7b than white smoke.

Therefore, the photoelectric smoke detector 1 of the present embodiment
Then, as shown in FIG. 3, the reference for distinguishing between white smoke and black smoke is set to, for example, a line L (y = L × x) shown in FIG. 4, and the output S1 of the first light receiving unit 7a and the When the ratio S2 / S1 to the output S2 of the second light receiving unit 7b satisfies the relationship S2 / S1> L, it is determined that the scattered light due to black smoke is detected. When it is determined that the smoke existing in the smoke sensing area 8 is black smoke, the threshold value is used to increase the sensor output of the photoelectric smoke detector 1 or to determine that smoke has been detected. Lower the alert level. This makes it possible to increase the sensitivity to black smoke and reduce the difference in sensitivity from white smoke. Various methods are conceivable for setting the line L (y = L × x). For example, black smoke and white smoke serving as a reference are used, and they are arbitrarily set where they can be identified.

As shown in FIG. 5, a criterion for distinguishing white smoke from black smoke is, for example, a line L (y = x,
L = 1), the output S1 of the first light receiving unit 7a and the second
May be compared with the output S2 of the light receiving unit 7b to determine that scattered light due to black smoke is detected when S2> S1. At this time, the line L (y = x, L =
It is necessary to adjust the gain of the amplifier of the light receiving unit 7 so that 1) becomes a reference. If it is determined that the smoke existing in the smoke sensing area 8 is black smoke, the sensor output of the photoelectric smoke sensor 1 is increased or the alarm level is reduced.
This makes it possible to increase the sensitivity to black smoke and reduce the difference in sensitivity from white smoke. According to this procedure, the output S1 of the first light receiving unit 7a and the output S2 of the second light receiving unit 7b are compared when white smoke and black smoke are distinguished, so that division is not used. The determination process can be performed by the subtraction, which has the effect of simplifying the determination process.

In the above-described embodiment, the light projecting axis and the two light receiving axes do not need to be on the same plane, and the respective optical axes may intersect three-dimensionally.

[Second Embodiment] As shown in FIG.
The photoelectric smoke detector 1 includes light emitting units 6a and 6b including light emitting diodes and the like provided in a dark box 4, and a light receiving unit 7 including a photodiode and the like provided with a light receiving axis shifted from the optical axis of the light emitting unit 6. And two light projecting sections 6a and 6b
Of the light receiving axis of the light receiving unit 7 are different from the light emitting axis of the light receiving unit 7. That is, for example, the angle A between the light projecting axis of the first light projecting unit 6a and the light receiving axis of the light receiving unit 7 is 120 °, and the light projecting axis of the second light projecting unit 6b and the light receiving axis of the light receiving unit 7 are set. Angle B with
Is set to 60 °. The angle A is about 110 ° to 130 °.
° and the angle B are desirably between 50 ° and 70 °, but are not limited thereto. The appearance of the photoelectric smoke detector 1 according to the second embodiment is the same as that shown in FIG.

The light emission timings of the two light emitting units 6a and 6b are shifted by a switching unit (not shown) so that light emission is performed at different timings. In the present embodiment, two light emitting units 6a,
A configuration is provided that has a switching unit for shifting the light emission timing of 6b by 0.5 seconds.

In the photoelectric smoke detector 1 having the above configuration,
The light receiving intensity at the light receiving unit 7 by the first light emitting unit 6a and the light receiving intensity at the light receiving unit 7 by the second light emitting unit 6b in white smoke (cotton wick dry smoke) and black smoke (kerosene combustion smoke) Fig. 4
It becomes the same relation as. Therefore, in the photoelectric smoke detector 1 of the present embodiment, as shown in FIG. 8, a criterion for discriminating between white smoke and black smoke is, for example, a line L (y = L × x) shown in FIG.
And the ratio S2 / S1 of the output S1 of the first light projecting unit 6a and the output S2 of the second light projecting unit 6b is S2 / S1>
In the case of L, it is determined that scattered light due to black smoke is detected. If it is determined that the smoke present in the smoke sensing area 8 is black smoke, the detector output of the photoelectric smoke detector 1 is increased, or an alarm which is a threshold when it is determined that smoke has been detected. Lower the level. Thereby, the sensitivity to black smoke is increased, and the difference in sensitivity from white smoke is reduced. Various methods are conceivable for setting the line L (y = L × x). For example, black smoke and white smoke serving as a reference are used, and they are arbitrarily set where they can be identified.

Further, a reference for discriminating between white smoke and black smoke is set, for example, on a line L (y = x, L = 1) shown in FIG.
The output S1 of the first light projecting unit 6a and the output S2 of the second light projecting unit 6b may be compared to determine that scattered light due to black smoke is detected when S2> S1. At that time, it is necessary to adjust the irradiation power of the LED or the like in each light emitting circuit section shown in FIG. 8 so that the line L (y = x, L = 1) shown in FIG. 6 becomes a reference. If it is determined that the smoke existing in the smoke sensing area 8 is black smoke, the sensor output of the photoelectric smoke sensor 1 is increased or the alarm level is reduced. This makes it possible to increase the sensitivity to black smoke and reduce the difference in sensitivity from white smoke. Also, according to this procedure, when discriminating between white smoke and black smoke, the output S1 of the first light emitting unit 6a and the second light emitting unit 6
Since the output S2 is compared with the output S2, the determination process can be performed by the subtraction without using the division, which has an effect that the determination process is simplified.

In the above-described embodiment, the light receiving axis and the two light projecting axes do not need to be on the same plane, and the respective optical axes may intersect three-dimensionally.

It is necessary to select an angle between the light emitting axis and the light receiving axis so that white smoke and black smoke can be easily distinguished. Therefore, FIG.
As shown in the figure, a fixed light emitting diode (center wavelength 9
An experiment is performed with a configuration in which two sets of lenses and photodiodes that can be moved arbitrarily are installed in the dark box 4 to determine an appropriate projection axis and reception axis.

First, photodiodes are arranged at the forward scattering angle and the back scattering angle, respectively. Note that FIG.
In general, the forward scattering angle refers to an angle between the light projecting axis and the light receiving axis in the range of 90 ° to 180 °, and the back scattering angle refers to the angle between the light projecting axis and the light receiving axis being 0 ° to 90 °. The range of °. At this time, in the case of white smoke, the ratio W2 / W1 of the received light intensity W1 based on the forward scattering angle and the received light intensity W2 based on the back scattering angle.
Compared to W1, the ratio B2 / B of the received light intensity B1 based on the forward scattering angle and the received light intensity B2 based on the back scattering angle in the case of black smoke.
1 increases. The result is shown in FIG.

FIG. 10 shows the ratio of the ratio B2 / B1 of the intensity of light received by black smoke to the ratio W2 / W1 of the intensity of light received by white smoke for each combination of scattering angles. It can be said that the larger this value is, the easier it is to distinguish between white smoke and black smoke. Therefore, from this result, it is considered that the combination of 120 ° and 60 ° is suitable for distinguishing white smoke from black smoke.

[0029]

As described above, according to the first aspect of the present invention, there is provided a light projecting unit for irradiating light to the smoke sensing region, and a light receiving unit for receiving scattered light due to smoke existing in the smoke sensing region. In the photoelectric smoke detector having a, a plurality of light projecting units or light receiving units are provided so that a plurality of angles between the light projecting axis and the light receiving axis are formed, and the smoke sensing area is determined by a plurality of light receiving intensities obtained by the light receiving unit. Has been added to determine whether the smoke present is white smoke or black smoke, so it is possible to capture the scattered light from multiple angles due to the smoke particles. This makes it possible to provide a highly reliable photoelectric smoke detector that performs smoke detection accurately regardless of the sensitivity difference between white smoke and black smoke.

According to the second aspect of the present invention, the first aspect is provided.
In the photoelectric smoke detector described, an output adjustment unit that adjusts the output or alarm level from the photoelectric smoke detector based on the result of the determination unit is added, so the sensitivity difference between white smoke and black smoke is automatically determined. This has the effect that it is possible to reduce the size.

According to the third aspect of the present invention, there is provided the first aspect.
3. The photoelectric smoke detector according to claim 2, further comprising a light projecting unit, a first light receiving unit, and a second light receiving unit, wherein a light receiving intensity detected by the first light receiving unit and a second light receiving unit. By comparing the ratio of the received light intensity detected by the white smoke and the black smoke in the determination unit by comparing the ratio of the received light intensity detected by the white smoke and the black smoke, the predetermined value suitable for discriminating the white smoke from the black smoke is used. By setting, there is an effect that it is possible to accurately discriminate between white smoke and black smoke.

According to the fourth aspect of the present invention, there is provided the first aspect.
3. The photoelectric smoke detector according to claim 2, further comprising a light projecting unit, a first light receiving unit, and a second light receiving unit, wherein the first light receiving unit detects the light based on a preset reference value. The light receiving intensity detected by the first light receiving unit and the light receiving intensity detected by the second light receiving unit are corrected so that the light intensity becomes equal to the light receiving intensity detected by the second light receiving unit. By comparing the white smoke with the white smoke in the judgment unit, the identification process can be determined by subtraction without using division, so that the process at the time of identification is simplified, and This has the effect of making it possible to identify black smoke.

According to the fifth aspect of the present invention, the third aspect is provided.
5. The photoelectric smoke detector according to claim 4, wherein an angle formed between the light projecting unit and the first light receiving unit is 110 ° to 130 ° around a central portion of the smoke sensing region, and the light projecting unit and the second light receiving unit are arranged in the second direction. The angle between the white smoke and the black smoke was made 50 ° to 70 °, so that the difference in output between the white smoke and the black smoke became clear, so that the white smoke and the black smoke could be more accurately distinguished. It has the effect that it becomes possible.

According to the sixth aspect of the present invention, a first aspect is provided.
Alternatively, in the photoelectric smoke sensor according to claim 2, the light emission timings of the first light emitting unit, the second light emitting unit, the light receiving unit, the first light emitting unit, and the second light emitting unit are set. A switching unit for switching, and comparing the ratio of the received light intensity of the scattered light by the first light emitting unit and the received light intensity of the scattered light by the second light emitting unit with a predetermined value set in advance. Since white smoke or black smoke is distinguished, it is possible to accurately distinguish between white smoke and black smoke by setting a predetermined value suitable for distinguishing between white smoke and black smoke. Since only one light receiving section (including a light receiving element and a light receiving circuit) sensitive to noise is used, it is possible to improve the noise resistance.

In the invention according to claim 7, claim 1 is
Alternatively, in the photoelectric smoke sensor according to claim 2, the light emission timings of the first light emitting unit, the second light emitting unit, the light receiving unit, the first light emitting unit, and the second light emitting unit are set. A switching unit for switching, wherein a light receiving intensity radiated by the first light emitting unit and detected by the light receiving unit and a light receiving intensity radiated by the second light emitting unit and detected by the light receiving unit are set at a preset reference value. The light receiving intensity emitted by the first light emitting unit and the light receiving intensity emitted by the second light emitting unit are corrected so as to be equal, and the corrected values are compared. Because it is possible to distinguish between black smoke and black smoke, it is possible to determine the identification by subtraction without using division, so that the processing at the time of identification is simplified and it is possible to distinguish between white smoke and black smoke This has the effect.

In the invention according to claim 8, claim 6
Alternatively, in the photoelectric smoke detector according to claim 7, the angle formed between the light receiving portion and the first light projecting portion is set to 110 ° to 130 ° around the center of the smoke sensing region, and the light receiving portion and the second light emitting portion are connected to each other. Since the angle between the light emitting portion and the light emitting portion is set to 50 ° to 70 °, the difference between the output of the white smoke and the output of the black smoke becomes clear, so that the white smoke and the black smoke can be more accurately distinguished. It has the effect that it becomes possible.

[Brief description of the drawings]

FIGS. 1A and 1B show a photoelectric smoke detector according to a first embodiment, wherein FIG. 1A is an external view and FIG.

FIG. 2 is a sectional view of another photoelectric smoke sensor according to the first embodiment, taken along line XX.

FIG. 3 is a schematic configuration diagram of a photoelectric smoke detector according to the first embodiment.

FIG. 4 shows the scattered light intensity of 120 ° in white smoke and black smoke and 6
It is a figure which shows the relationship of the scattered light intensity of 0 degree.

FIG. 5 is a schematic configuration diagram of another photoelectric smoke detector according to the first embodiment.

FIG. 6 shows white smoke and black smoke when GAIN adjustment is performed.
It is a figure which shows the relationship between the scattered light intensity of 20 degrees, and the scattered light intensity of 60 degrees.

FIG. 7 is a cross-sectional view of the photoelectric smoke detector according to the second embodiment.
It is X sectional drawing.

FIG. 8 is a schematic configuration diagram of a photoelectric smoke detector according to a second embodiment.

FIG. 9 is a cross-sectional view taken along the line XX of the experimental apparatus having the same shape as the photoelectric smoke detector used for finding an appropriate angle.

FIG. 10: White smoke 2 for a combination of scattering angles
It is a figure showing the relationship between the ratio of two light reception intensity and the ratio of two light reception intensity by black smoke.

FIG. 11 is a diagram showing a definition of an angle of an optical system of the photoelectric smoke detector.

FIG. 12 is an external view of a conventional photoelectric smoke detector.

FIG. 13 is a sectional view of a conventional photoelectric smoke detector taken along line XX.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoelectric smoke detector 2 body 3 smoke detector 4 dark box 5 labyrinth 6 light emitter 7 light receiver 8 smoke sensing area

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[Procedure amendment]

[Submission date] January 30, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction contents]

[First Embodiment] As shown in FIG.
The photoelectric smoke detector 1 includes a light emitting unit 6 including a light emitting diode or the like provided in a dark box 4 and light receiving units 7a and 7 including a photodiode or the like provided with a light receiving axis shifted from the optical axis of the light emitting unit 6.
b, and the angles formed by the light projecting axis of the light projecting unit 6 and the light receiving axes of the two light receiving units 7a and 7b are different from each other. That is, for example, the angle A formed between the light emitting axis of the light projecting unit 6 and the light receiving axis of the first light receiving unit 7a is 120 °, and the light emitting axis of the light projecting unit 6 and the light receiving axis of the second light receiving unit 7b are set. Angle B with
Is set to 60 °. The angle A is about 110 ° to 130 °.
° and the angle B are desirably between about 50 ° and 70 °, but are not limited thereto.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction contents]

[Second Embodiment] As shown in FIG.
The photoelectric smoke detector 1 includes light emitting units 6a and 6b including light emitting diodes and the like provided in a dark box 4, and a light receiving unit 7 including a photodiode and the like provided with a light receiving axis shifted from the optical axis of the light emitting unit 6. And two light projecting sections 6a and 6b
Of the light receiving axis of the light receiving unit 7 are different from the light emitting axis of the light receiving unit 7. That is, for example, the angle A between the light projecting axis of the first light projecting unit 6a and the light receiving axis of the light receiving unit 7 is 120 °, and the light projecting axis of the second light projecting unit 6b and the light receiving axis of the light receiving unit 7 are set. Angle B with
Is set to 60 °. The angle A is about 110 ° to 130 °.
° and the angle B are desirably between about 50 ° and 70 °, but are not limited thereto. The appearance of the photoelectric smoke detector 1 according to the second embodiment is the same as that shown in FIG.

Claims (8)

[Claims] 1. A photoelectric smoke sensor having a light projecting section for irradiating light to a smoke sensing area and a light receiving section for receiving light scattered by smoke present in the smoke sensing area, wherein a light projecting axis and a light receiving axis are A plurality of light projecting parts or light receiving parts are provided so as to form a plurality of angles, and a plurality of light receiving intensities obtained by the light receiving parts determine whether the smoke present in the smoke sensing area is white smoke or black smoke. A photoelectric smoke detector to which a discriminating unit is added. 2. The photoelectric smoke detector according to claim 1, further comprising an output adjusting unit for adjusting an output or a warning level from the photoelectric smoke detector based on a result of the determination unit. 3. A light receiving unit comprising: a light projecting unit; a first light receiving unit; and a second light receiving unit;
3. A white smoke or black smoke is distinguished in the determination unit by comparing a ratio of the light receiving intensity detected by the light receiving unit with a predetermined value set in advance. The photoelectric smoke detector as described. 4. A light-emitting unit, a first light-receiving unit, and a second light-receiving unit, wherein a light-receiving intensity detected by the first light-receiving unit at a predetermined reference value and a light-receiving intensity of the second light-receiving unit are determined. The light receiving intensity detected by the first light receiving unit and the light receiving intensity detected by the second light receiving unit are corrected so that the detected light receiving intensity becomes equal, and the corrected values are compared to determine the determining unit. 3. The photoelectric smoke sensor according to claim 1, wherein the smoke is distinguished from white smoke or black smoke. 5. An angle between the light projecting portion and the first light receiving portion is set to 110 ° to 130 ° around a center of the smoke sensing region,
The photoelectric smoke sensor according to claim 3 or 4, wherein an angle formed between the light projecting portion and the second light receiving portion is set to 50 ° to 70 °. 6. A light emitting device comprising: a first light projecting unit, a second light projecting unit, a light receiving unit, and a switching unit for switching light emission timings of the first light projecting unit and the second light projecting unit. The judgment unit discriminates between white smoke and black smoke by comparing a ratio of the intensity of the scattered light received by the first light emitting unit and the intensity of the scattered light received by the second light emitting unit with a predetermined value. The photoelectric smoke detector according to claim 1 or 2, wherein the photoelectric smoke detector is configured to perform the operation. 7. A light emitting device comprising: a first light projecting unit, a second light projecting unit, a light receiving unit, and a switching unit for switching light emission timings of the first light projecting unit and the second light projecting unit. At the set reference value, the first light-emitting portion irradiates the first light-receiving portion and detects the light-receiving intensity at the light-receiving portion, and the first light-emitting portion irradiates and detects the first light-receiving intensity at the light-receiving portion so that the received light intensity becomes equal. By correcting the received light intensity emitted by the light emitting unit and the received light intensity emitted by the second light emitting unit, and comparing the corrected values, the determination unit can determine whether white smoke or black smoke is present. The photoelectric smoke detector according to claim 1 or 2, wherein: 8. An angle between the light receiving portion and the first light projecting portion is set to 110 ° to 130 ° around a central portion of the smoke sensing region,
The photoelectric smoke sensor according to claim 6 or 7, wherein an angle formed between the light receiving unit and the second light projecting unit is set to 50 ° to 70 °.