JP3095884B2 - Photoelectric separated smoke detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light-emitting device which emits a light beam to a reflector disposed at a predetermined distance, receives reflected light from the reflector, and sets a light receiving level in advance by smoke entering a monitoring area. The present invention relates to a photoelectric separation type smoke detector that performs a sensing output when a value falls below a set threshold value.

[0002]

2. Description of the Related Art Heretofore, the following is known as such a photoelectric separation type smoke detector. In other words, a reflection plate is arranged on the optical axis of the light emitted from the light-emitting unit, and the light reflected by the reflection plate is received by the light-receiving unit, and the light is blocked by the invasion of smoke. Is detected, and a fire is judged based on the detected light receiving level.

FIG. 6A shows a schematic configuration of a conventional photoelectric separation type smoke detector. As can be seen from FIG. 6 (a), in the conventional photoelectric separation type smoke detector, the light of the light emitting element 102 of the sensor main body 100 is collimated by the lens 104 and becomes a light projection beam 106 to traverse the monitoring space. Then, the beam 107 whose direction has been changed by 180 ° by the recursive mirror (reflection plate) 101 is condensed by the light receiving lens 105 and received by the light receiving element 103. Here, if smoke 110 generated by the fire exists in the monitoring space, the beam is dimmed and received. For example, a fire signal is generated when the light receiving signal of 100 mv is reduced to 50 mv.

In such a fire detector, for example, as shown in FIG. 6 (b), when a shield 121 other than smoke exists in the monitoring area in the normal monitoring state, the light receiving output on the light receiving section side Erroneous fire detection may occur due to dropping In such a case, a countermeasure has been taken to go to the site where the fire detector is installed, confirm the existence of the shield, remove the shield, and return to the normal monitoring state. In addition, in order to avoid such a situation that the light is not monitored and thus the light is not monitored, a trouble signal is issued when the light receiving signal becomes extremely small to call attention.

[0005]

In the above-mentioned conventional photoelectric separation type smoke detector, the shield 121 having a low reflectance is used.
In the case of the shielding by the above method, if the light receiving level of the light receiving unit is reduced by the shielding object and the trouble detecting operation is performed, it is possible to cope with the above-described method. However, when the reflectance of the shield is high, the light from the light emitting unit is
There is a problem in that the light is reflected at 20 and returns to the light receiving section, so that the sensor determines that it is normal. In that case, the shield 12
In the range from 0 to the reflection plate 101, there is a problem that monitoring becomes impossible and a report is lost.

In many cases, the detector is installed near the ceiling of a building. However, pipes and ducts are often arranged near the ceiling of the building, and when these are within the so-called critical radius, this sensor is effective to avoid false alarms due to the reflected light Nevertheless, there was a problem that it could not be installed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and it is possible to accurately determine the presence of a shield other than smoke in a monitoring area, and to reflect the reflectance even if a shield exists. Regardless of the above, an object of the present invention is to provide a photoelectric separation type smoke detector capable of making an accurate fire judgment by calculating the true reflected light amount from the reflection plate by canceling the influence.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned conventional problems, a first aspect of the present invention is to provide a fire monitoring light emitting unit which emits a light beam to a reflector disposed at a fixed distance, In the photoelectric separation type smoke sensor comprising a light receiving unit for receiving light reflected from the plate and a determination unit for performing a sensing output when the light receiving output of the light receiving unit is equal to or less than a predetermined threshold value, A fire monitoring light emitting unit disposed at a predetermined distance from the fire monitoring light emitting unit at a position off the optical axis connecting the light emitting unit, the reflector, and the light receiving unit; Intermittently turn on and off the object monitoring light emitting unit,
The amount of light received when the fire monitoring light emitting unit is lit and the amount of light received when the shield monitoring light emitting unit is lit, and when the fire monitoring light emitting unit is illuminated and when a predetermined obstacle is not present From the ratio of the amount of light received when the light emitting part is lit, the amount of light reflected by the shielding object is determined, and the difference between the amount of reflected light and the amount of light received when the light emitting part for fire monitoring is lit is compared with the threshold value to make a fire judgment. I have.

According to a second aspect of the present invention, there is provided a fire monitoring light emitting unit for emitting a light beam to a reflector disposed at a predetermined distance, and a fire monitoring light receiving unit for receiving light reflected from the reflector. And a photoelectric separation type smoke sensor comprising a determination unit that performs a sensing output when the light receiving output of the light receiving unit is equal to or less than a preset threshold, wherein the light emitting unit and the reflector, the fire monitoring light receiving unit A fire monitoring light receiving unit disposed at a predetermined distance from the fire monitoring light receiving unit at a position deviated from the optical axis to be connected, intermittently turning on the light emitting unit, the fire monitoring light receiving unit and the shield The light receiving unit alternately receives light by the monitoring light receiving unit, the light receiving amount when the fire monitoring light receiving unit receives the light, the light receiving amount when the shield monitoring light receiving unit receives the light, and the fire when the predetermined shielding object does not exist. Light receiving unit for monitoring and monitoring of shielding From the ratio of the amount of light received by the light receiving unit, the amount of light reflected by the shielding object is determined, and the difference between the amount of reflected light and the amount of light received by the fire monitoring light receiving unit is compared with the above threshold value to make a fire judgment. I have.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment of a photoelectric separation type smoke detector according to the present invention.
FIG. 3 is a perspective view showing the overall configuration of the example. As shown in FIG. 1, the photoelectric separation type smoke detector emits a light beam to a reflector 2 disposed at a certain distance from the sensor body 1 and receives reflected light from the reflector 2. Accordingly, when the light reception output is equal to or less than a preset threshold, a fire detection output is performed. In this embodiment, two light-emitting portions are provided at predetermined intervals by utilizing the property of a retroreflective mirror used for the reflection plate 2, and the reflected light is received based on the difference in the angle of incidence on each reflection plate 2. The true reflected light amount by the reflection plate 2 is obtained based on the difference in the amount of received light in the sections, and the influence of the shield is removed.

First, the configuration of the sensor body 1 will be described.
FIG. 2 is a configuration block diagram illustrating the configuration of the sensor main body 1. The sensor body 1 is roughly divided into a light emitting unit 4, a light receiving unit 5, and a determination unit 6. First, the light emitting unit 4 includes a fire monitoring light emitting element 10 such as a light emitting diode emitting near-infrared light, a shielding object monitoring light emitting element 30, and a fire monitoring light emitting element 10.
And a light emission switching control unit 31 for switching the light emission of the shielding object monitoring light emitting element 30, and a switching control unit 3 for controlling these switching.
2. Light emitting element 1 for fire monitoring via light emission switching control unit 31
0, a light emission drive unit 11 that drives the shield monitoring light emitting element 30, a light emission / reception control unit 12 that controls light emission and light reception operations,
Fire monitoring light emitting element 10 and shield monitoring light emitting element 30
And a timer 33 for setting a switching time, a light emission cycle, and the like. The fire monitoring light emitting element 10 and the shield monitoring light emitting element 30 are arranged at a predetermined distance (for example, 300 mm) on the same plane as the reflector 2.

Next, the light receiving section 5 includes a light receiving element 13 for receiving the light reflected by the reflector 2, an amplification circuit 15 for amplifying an output from the light reception element 13, and an analog signal from the amplification circuit 15 for converting a digital signal into a digital signal. An A / D converter 16 converts the received light data. Here, the light receiving element 13 is disposed near the fire monitoring light emitting element 10 (for example, 20 m).
m), it is arranged away from the shielding object monitoring light emitting element 30.

The judging section 6 switches a data storage location of the output of the light receiving element 13 depending on whether the light from the fire monitoring light emitting element 10 or the light from the shield monitoring light emitting element 30 is received. 34, and a light reception data storage unit 1 for storing light reception data of light from the fire monitoring light emitting element 10.
7. A light reception data storage unit 37 for storing light reception data of light from the shielding object monitoring light emitting unit 30, a calculation unit 39 for calculating the amount of reflected light from the shielding object using both the reception light data, and setting a threshold value for fire detection in advance. And a fire determining unit 19 for making a fire determination based on the threshold. The switching of the light reception data by the changeover switch 34 is performed simultaneously when the switching control unit 32 switches the light emission of the fire monitoring light emitting element 10 and the light emission of the shield monitoring light emitting element 30.

On the other hand, in the present embodiment, a collimating lens 51 for collimating light is provided on the front surface of the fire monitoring light emitting element 10 and the shielding object monitoring light emitting element 30, and a reflecting plate is provided on the front surface of the light receiving element 13. A condensing lens 52 for condensing the reflected light from 2 is provided.

The reflector 2 uses a so-called retro-reflective mirror, and the light emitted from the fire monitoring light emitting element 10 is collimated by the collimating lens 51 and changes its direction by 180 ° by the reflector 2 so as to change the direction of the sensor body 1. Light receiving unit 5
However, the light emitted from the shielding object monitoring light emitting element 30 does not directly return to the light receiving unit 5 due to a difference in the incident angle to the reflector 2.

Next, the operation of the first embodiment configured as described above will be described. In this embodiment, the fire monitoring light emitting element 10 and the shield monitoring light emitting element 30 are intermittently turned on alternately at a predetermined cycle.

As described above, in this embodiment, only the light emitted from the fire monitoring light emitting element 10 returns directly from the reflection plate 2 to the light receiving element 13, and almost all the light emitted from the shielding object monitoring light emitting element 30 is emitted. The light receiving element 13 does not receive light. FIG. 3 shows this relationship. That is, the retro-reflective mirror has a property that the reflected light is substantially reflected in the direction of the incident light. Therefore, the light emitted from the fire monitoring light emitting element 10 is substantially reflected to the front as shown in FIG. 3A, and the incident light is reflected by the fire monitoring light emitting element 10 at an angle θ ₁ (for example, at a monitoring distance of 50 m). 20mm distance from element 13
In this case, the reflected light directly reaches the light receiving element 13 arranged in the direction of 0.02 °).

On the other hand, the light emitted from the shielding object monitoring light emitting element 30 is located at a position shifted from the optical axis connecting the fire monitoring light emitting element 10 with the reflector 2 and the light receiving element 13. As shown in FIG. 3B, the light obliquely enters the reflecting plate 2 and is reflected in that direction, so that it is directed in the direction of the angle θ ₂ (0.37 ° in the above example) with respect to the optical axis. Very little reflected light reaches the arranged light receiving element 13.

As described above, in normal times (when there is no smoke and no obstruction), only the reflected light of the light mainly emitted from the fire monitoring light emitting element 10 enters the light receiving element 13. FIG. 4 shows experimental data indicating the distance between the light emitting element 10 and the light receiving element 13 (distance between lenses) and the amount of light received by the light receiving element 13. As can be seen from FIG. 4, the relationship between the distance between the light emitting element 10 and the light receiving element 13 and the amount of received light is substantially linear. In addition, the two light emitting elements 10, 30
The ratio of the amount of received light depends on the length of the monitoring distance,
This has the relationship shown in Table 1 below. Therefore, when the sensor body 1 is installed, the ratio of the amount of received light between the two is determined in advance and determined in consideration of the length of the monitoring distance so as to be, for example, 10: 1.

[Table 1] (Between light emitting element for fire monitoring and light receiving element: 20 mm) (Between light emitting element for shielding object and light receiving element: 300 mm)

Next, consider a case where a shield 9 as shown in FIG. 1 exists in the monitoring area. In this case, the light emitted from both light emitting elements 10 and 30 is applied to the shield 9.
Illuminated and reflected. Then, the reflected light enters the light receiving element 13 together with the reflected light from the reflection plate 2. That is, in order to make a correct fire judgment, it is necessary to make a judgment by subtracting the light reflected from the shield from the received light amount.

Therefore, in the present invention, the amount of reflected light from the shield is determined as follows. First, it is assumed that the fire monitoring light emitting element 10 is used when no shield exists.
Received light amount chi ₂ when but a light receiving amount chi ₁ of the light receiving element 13 when lit, which also shield the monitoring light emitting element 30 emits light
Set the ratio with This is because the two light emitting elements 1
This value is determined by the distance between 0, 30 and the light receiving element 13. In this embodiment, it is assumed that the monitoring distance is 50 m.
χ ₁ : χ ₂ = 10: 1.

Next, assuming that the light receiving amounts of the light receiving elements 13 when the light emitting elements 10 and 30 are turned on in the presence of the shielding object are A ₁ and A ₂ , respectively, A ₁ and A ₂ are the above light receiving amounts χ ₁ , a value obtained by adding the amount of received reflected light by the obstacle to the chi _2. That is, assuming that the amounts of light reflected from the shield by the lighting of the light emitting elements 10 and 30 are B ₁ and B ₂ , A ₁ and A ₂ can be expressed as follows.

[Equation 1] A ₁ = B ₁ + χ ₁ · X

[Equation 2] A ₂ = B ₂ + χ ₂ · X

Here, the reflected light from the shield becomes scattered light, and the amount of the reflected light is less affected by the distance from each of the light emitting elements 10 and 30, so that B ₁ = B ₂ = B. Therefore, B can be obtained by simultaneously solving equations 1 and 2 from the actually measured data A ₁ and A ₂ .

In this embodiment, the above operation is performed by the operation unit 3
9 does. That is, read data from the receiving data storage unit 17 and 37, determine the amount of reflected light (B) from shield by applying a predetermined chi ₁ and chi ₂ ratio thereto. If the amount of light reflected from the shield is obtained in this way, the difference between the amount of light received when the fire monitoring light emitting element 10 is turned on and the amount of reflected light can be obtained to obtain the true amount of reflected light from the reflector 2. . Then, the fire judgment is made by comparing the value in the fire judgment unit 19 with a threshold value preset in the threshold value setting unit 18.

These series of calculations are performed every time each of the light emitting elements 10 and 30 is turned on and off intermittently. That is,
A fire judgment is made by comparing with the immediately preceding data. Accordingly, accurate fire determination can be made even when the number of shields newly increases or the amount of light reflected by the shields changes.

FIG. 5 is a perspective view showing a sensor main body 1 according to a second embodiment of the present invention. In the case of the present embodiment, two light-emitting elements are provided in the previous embodiment, whereas two light-receiving elements are provided. The configuration of the sensor main body 1 of the present embodiment is almost the same as that of the first embodiment shown in FIG.
Instead, two light receiving elements are provided: a fire monitoring light receiving element 53 and a shielding object monitoring light receiving element 54, and only one light emitting element (light emitting element 50) is provided. Also,
In this case, the switching control unit 32 switches which of the light receiving elements receives light and which of the data storage units receives the received light data.

In this embodiment, the light emitting element 50 is intermittently lit. Then, in synchronization with the lighting, the light receiving element that receives the reflected light is switched. In this case, the reflected light from the reflector 2 is directly incident on the fire monitoring light receiving element 53 according to the principle described in the first embodiment. Also, the reflected light from the reflector 2 hardly enters the light receiving element 54 for monitoring the shield. And the ratio of the incident light amount is the first
The distance between the light receiving elements 53 and 54 and the light emitting element 50 is set so as to be a predetermined value as in the embodiment.

Therefore, in this embodiment, similarly to the first embodiment, the arithmetic unit 39 solves the simultaneous equations based on the obtained data to obtain the amount of light reflected by the shield, and the true amount of reflected light is calculated from this. The fire is determined by making a decision and comparing it with a threshold value in the fire determination unit 19.

[0029]

As described above, according to the first aspect of the present invention, while the fire monitoring light emitting unit is arranged close to the light receiving unit,
Dispose the shielding object monitoring light emitting units at a position distant from the light receiving unit, alternately intermittently illuminate them, perform a predetermined calculation based on the received light amount, and obtain the amount of light reflected by the shielding object to obtain the amount of reflected light. There is an effect that the influence of the shield can be canceled and the true reflected light amount from the reflector can be obtained. Thus, accurate fire determination can be performed even when the shield is in the monitoring area.

According to the second aspect of the present invention, a fire monitoring light receiving unit is provided in proximity to the light emitting unit, and a shield monitoring light receiving unit is provided at a position distant from the light receiving unit. The reflected light is received alternately, and a predetermined calculation is performed based on the received light amount to obtain the amount of the reflected light by the shield. There is an effect that the amount of reflected light can be obtained. Thus, accurate fire determination can be performed even when the shield is in the monitoring area.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an overall configuration of a photoelectric separation type smoke detector according to a first embodiment of the present invention.

FIG. 2 is a configuration block diagram of a sensor main body of the photoelectric separation type smoke sensor according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram showing how light rays are reflected by a reflector using a recursive mirror;

FIG. 4 is a graph showing a relationship between a distance between a light emitting element and a light receiving element and an amount of received light.

FIG. 5 is a perspective view showing a configuration of a photoelectric separation type smoke detector according to a second embodiment of the present invention on a sensor main body side.

FIG. 6 is an explanatory diagram showing an example of a conventional photoelectric separation type smoke detector.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sensor main body 2 Reflector 4 Light emitting part 5 Light receiving part 6 Judgment part 9 Shielding object 10 Fire monitoring light emitting element 13 Light receiving element 30 Shielding object monitoring light emitting element 39 Operation part 50 Light emitting element 53 Fire monitoring light receiving element 54 Shielding object Monitoring light receiving element

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-184041 (JP, A) JP-A-59-91340 (JP, A) Fully open 63-143996 (JP, U) Really open Showa 57- 99290 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) G08B 17/103 G01N 21/59

Claims (2)

(57) [Claims] 1. A fire monitoring light-emitting unit that emits a light beam to a reflector disposed at a predetermined distance, a light-receiving unit that receives light reflected from the reflector, and a light-receiving output of the light-receiving unit is set in advance. In a photoelectric separation type smoke detector including a determination unit that performs a sensing output when the value is equal to or less than a set threshold value, the fire detection device is provided at a position off an optical axis connecting the fire monitoring light emitting unit, the reflector, and the light receiving unit. A light-emitting unit for monitoring a shield disposed at a predetermined distance from the light-emitting unit for monitoring, the intermittent lighting of the light-emitting unit for fire monitoring and the light-emitting unit for shield monitoring alternately, and the lighting of the fire-monitoring light-emitting unit And the amount of light received when the shield monitoring light-emitting unit is turned on, and the amount of light received when the fire monitoring light-emitting unit is turned on and when the shield monitoring light-emitting unit is turned on when there is no predetermined shield. From the ratio of Because, photoelectric separated smoke sensor and performs fire determination by comparing the received light amount of the difference and the threshold value in the amount of reflected light and fire monitoring emission portion during lighting. 2. A light emitting unit for emitting a light beam to a reflector disposed at a certain distance, a fire monitoring light receiving unit for receiving reflected light from the reflector, and a light receiving unit for the fire monitoring light receiving unit. In a photoelectric separation type smoke detector including a determination unit that performs a sensing output when an output is equal to or less than a preset threshold value, a position deviated from an optical axis connecting the light emitting unit, the reflector, and the fire monitoring light receiving unit. A light-shielding object monitoring light receiving unit disposed at a predetermined distance from the fire monitoring light-receiving unit. The light-emitting unit is intermittently lit, and the fire-monitoring light-receiving unit and the shielding object monitoring light-receiving unit are alternately turned on. And the amount of light received at the time of receiving the fire monitoring light receiving unit and the amount of light received at the time of receiving the shielding object monitoring light receiving unit, and at the time of receiving the fire monitoring light receiving unit when there is no predetermined shielding object. Amount of light received when receiving light from the receiver Determining the amount of light reflected by the shielding object from the ratio, and comparing the difference between the amount of reflected light and the amount of light received when receiving the light for fire monitoring with the threshold value to determine whether a fire has occurred. sensor.