JPH05334582A - Photoelectric separtion type smoke sensor - Google Patents

Abstract

PURPOSE:To accurately judge a fire by reflection light quantity from a light reflection board even when there is a shield excepting for a smoke in a monitoring area. CONSTITUTION:This smoke sensor is provided with a fire sensoring light emitting part 10 emitting light to the reflection board 2, a light receiving part receiving reflection light from the reflection board 2, a judgement part outputting a sense when the received output is not over a set threshold value and a shield monitoring light-emitting part 30 arranged by separating from the fire sensoring light-emitting part 10 at a position away from an optical axis connecting the fire sensoring light emitting part 10, the reflection board 2 and the light- receiving part. The fire sensoring light-emitting part 10 and the shield sonsoring light-emitting part 30 are alternately lighted so as to obtain light quantity reflected by the shild from the ratio of light-receiving quantity at the time of the lighting of the fire sensoring light-emitting part, that at the time of the lighting of the shild sensoring light-emitting part and that at the time of the lighting of both parts when the shild 9 does not exist and to judge a fire by comparing the difference of light-receiving quantity at the time of the lighting of the fire sensoring light-emitting part and the threshold value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention emits a light beam to a reflector plate arranged at a certain distance, receives the reflected light from the reflector plate, and the smoke received in the monitoring area causes the light reception level to be preset. The present invention relates to a photoelectric separation type smoke sensor that performs a sensing output when the threshold value is below a set threshold value.

[0002]

2. Description of the Related Art Conventionally, the following is known as such a photoelectric type smoke detector. That is, a reflection plate is arranged on the optical axis of the light emitted from the light emitting unit, the light reflected by the reflection plate is received by the light receiving unit, and the light is blocked by the invasion of smoke, so that the light receiving level of the light receiving unit changes. Is detected, and a fire is judged based on the detected light receiving level.

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

In such a fire detector, for example, as shown in FIG. 6B, when there is a shield 121 other than smoke in the monitoring area in the normal monitoring state, the light receiving output on the light receiving unit side The fire may be accidentally detected because the fire drops. In such a case, a staff member goes out to the site where the fire detector is installed, confirms the presence of the shield, and removes the shield to return to the normal monitoring state. Further, in order to avoid such an unmonitored state due to the light being blocked by a shield, there is also a device that issues a trouble signal to call attention when the light reception signal becomes extremely small.

[0005]

By the way, in the above conventional photoelectric separation type smoke sensor, the shield 121 having a low reflectance is used.
In the case of shielding by the above method, if the light receiving level of the light receiving unit is lowered by the shielding object and the trouble detecting operation is performed, it is possible to deal with it by the above method for the time being. However, when the reflectance of the shield is high, the light from the light emitting portion is shielded by the shield 1.
There is a problem that the sensor determines that the light is normal because the light is reflected at 20 and returns to the light receiving portion. In that case, the shield 12
In the range from 0 to the reflector 101, there is a problem that monitoring becomes impossible and a false alarm is given.

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

The present invention has been made in order to solve the above problems, and it is possible to accurately determine the presence of a shield other than smoke in the monitoring area, and even if there is a shield, its reflectance is high. Despite the above, it is an object of the present invention to provide a photoelectric separation type smoke sensor that can make an accurate fire judgment by canceling out the influence and obtaining the true amount of reflected light from the reflector.

[0008]

In order to solve the above-mentioned conventional problems, the present invention according to claim 1 is directed to a fire monitoring light-emitting portion which emits a light beam to a reflector plate arranged at a fixed distance, and the reflection member. In the photoelectric separation type smoke detector, which is provided with a light receiving unit for receiving the reflected light from the plate and a judging unit for making a sensing output when the light receiving output of the light receiving unit is less than or equal to a preset threshold, The fire-monitoring light-emitting unit and the shield are provided with a shield-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 turns on the light emitting unit for object monitoring,
Light-receiving amount when the light emitting unit for fire monitoring is turned on, light receiving amount when the light-emitting unit for shielding object monitoring is turned on, and when the light-emitting unit for fire monitoring is turned on and for shielding object monitoring when a predetermined shield does not exist As a configuration for determining a fire by obtaining the amount of light reflected by the shielding object from the ratio of the amount of light received when the light emitting unit is turned on and comparing the difference between the amount of reflected light and the amount of light received when the light emitting unit for fire monitoring is turned on with the threshold value There is.

Further, according to the present invention of claim 2, a fire monitoring light emitting section for emitting a light beam to a reflecting plate arranged at a certain distance, and a fire monitoring light receiving section for receiving the reflected light from the reflecting plate. And a photoelectric separation type smoke detector including a determination unit that performs a detection output when the light reception output of the light reception unit is less than or equal to a preset threshold, the light emission unit, the reflector, and the fire monitoring light reception unit are provided. It has a shielding object monitoring light receiving section arranged at a predetermined distance from the fire monitoring light receiving section at a position off the optical axis to be connected, and the light emitting section is intermittently turned on, and the fire monitoring light receiving section and the shielding object. Receiving light alternately 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, and the fire when the predetermined shield does not exist. Light receiving part for monitoring When receiving light and monitoring shields As a configuration for making a fire judgment by obtaining the amount of light reflected by a shielded object from the ratio of the amount of light received when the light receiving unit receives light, and comparing the difference between the amount of reflected light and the amount of light received when receiving the light receiving unit for fire monitoring with the above threshold value. There is.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment of the photoelectric separated smoke detector of the present invention.
2 is a perspective view showing the overall configuration of the embodiment of FIG. As shown in FIG. 1, this photoelectric separation type smoke detector emits a light beam to a reflector plate 2 arranged at a certain distance from the detector body 1 and receives the reflected light from the reflector plate 2. Thus, when the received light output is less than or equal to a preset threshold value, a fire detection output is performed. In the present embodiment, in particular, by utilizing the property of the retroreflector used in the reflector 2, two light emitting portions are provided at a predetermined interval, and the reflected light is received based on the difference in the incident angle to each reflector 2. The true reflected light amount by the reflection plate 2 is obtained based on the difference in the amount of light received at each part, and the influence of the shield is removed.

First, the structure of the sensor body 1 will be described.
FIG. 2 is a configuration block diagram showing the configuration of the sensor body 1. The sensor body 1 is roughly divided into a light emitting section 4, a light receiving section 5, and a judging section 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 shield 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 light emitting element 30 for monitoring the shield, and a switching control unit 3 for controlling these switching.
2. Fire monitoring light emitting element 1 via the light emission switching control unit 31
0 and a light emission drive unit 11 that drives the light emitting element 30 for monitoring the shield, a light reception and emission 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 a plane having the same distance as the reflector 2.

Next, the light receiving section 5 receives the light reflected by the reflecting plate 2, a light receiving element 13, an amplifier circuit 15 for amplifying the output from the light receiving element 13, and an analog signal from the amplifier circuit 15 as a digital signal. It is composed of an A / D converter 16 for converting the received light data. Here, the light receiving element 13 is arranged near the fire monitoring light emitting element 10 (for example, 20 m
m), and is arranged apart from the light emitting element 30 for monitoring the shield.

Further, the judging section 6 switches the data storage location depending on whether the output of the light receiving element 13 is the light received from the fire monitoring light emitting element 10 or the light receiving from the shield monitoring light emitting element 30. 34 and a received light data storage unit 1 for storing received light data of light from the fire monitoring light emitting element 10.
7. A received light data storage unit 37 that stores received light data of light from the shield monitoring light emitting unit 30, a calculation unit 39 that calculates the amount of reflected light from the shield using both received light data, and a threshold for fire detection is set in advance. The threshold value setting unit 18 and the fire determination unit 19 that makes a fire determination based on the threshold value. The light receiving data is switched by the changeover switch 34 at the same time 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 this 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 condenser lens 52 for condensing the reflected light from 2 is provided.

The reflector 2 uses a so-called recursive mirror, and the light emitted from the fire-monitoring light emitting element 10 is collimated by the collimator lens 51 to change its direction by 180 ° by the reflector 2 and the sensor body 1 Light receiving part 5
However, the light emitted from the shielding-object monitoring light emitting element 30 does not directly return to the light receiving section 5 due to the difference in the incident angle to the reflecting plate 2.

Next, the operation of the first embodiment constructed as above will be described. In the present 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 reflector 2 to the light receiving element 13, and almost all the light emitted from the shield monitoring light emitting element 30. The light receiving element 13 does not receive light. FIG. 3 shows this relationship. That is, the retroreflector has the property that the reflected light is reflected in the direction of almost the incident light. Therefore, the light emitted from the fire-monitoring light emitting element 10 is reflected almost in the front as shown in FIG. 3A, and the incident light and the angle θ ₁ (for example, the fire-monitoring light emitting element 10 at the monitoring distance of 50 m and the light receiving element) are received. Distance from element 13 is 20 mm
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-monitoring light-emitting element 30 is arranged at a position deviated 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 is obliquely incident on the reflection plate 2 and is reflected in that direction, so that it is in the direction of the angle θ ₂ (0.37 ° according to the previous example) with the optical axis. Only a very small amount of reflected light reaches the light receiving element 13 arranged.

As described above, in a normal state (a state in which there is neither smoke nor a shield), only the reflected light of the light mainly emitted from the light emitting element 10 for fire monitoring enters the light receiving element 13. FIG. 4 shows experimental data showing 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 almost a linear relationship. In addition, both the light emitting elements 10 and 30
The ratio of the amount of received light due to changes with the length of the monitoring distance,
This has the relationship shown in Table 1 below. Therefore, when the sensor main body 1 is installed, the ratio of the light receiving amounts of the both 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 light shielding and light receiving element: 300 mm)

Next, consider the case where the 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 directed to the shield 9.
Is illuminated and reflected. Then, the reflected light is incident on 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 reflected light from this shield from the received light amount.

Therefore, in the present invention, the amount of light reflected from the shield is determined as follows. First, as a premise, the fire-monitoring light-emitting element 10 when there is no shield
And the received light amount χ ₁ of the light receiving element 13 when is turned on, and the received light amount χ ₂ when the shield monitoring light emitting element 30 emits light.
Set the ratio with. This is the same for both light emitting elements 1 as described above.
It is a value determined by the distance between 0 and 30 and the light receiving element 13, and 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 shield are A ₁ and A ₂ , respectively, these A ₁ and A ₂ are the above received light amounts χ ₁ , Χ ₂ plus the amount of light received by the shield. That is, if the amounts of light reflected from the shield due to lighting of the light emitting elements 10 and 30 are B ₁ and B ₂ , then A ₁ and A ₂ can be expressed as follows.

[Equation 1] A ₁ = B ₁ + χ ₁ · X

[Formula 2] A ₂ = B ₂ + χ ₂ · X

Here, the light reflected from the shield becomes scattered light, and the influence of the distance from each of the light emitting elements 10 and 30 on the amount of light is small, and B ₁ = B ₂ = B can be set. Therefore, B can be obtained by simultaneously solving the equations (1) and (2) from the measured A ₁ and A ₂ data.

In the present embodiment, the above calculation is performed by the calculation unit 3
9 does. That is, the amount of reflected light (B) from the shield is obtained by reading the data from the received light data storage units 17 and 37 and applying a predetermined ratio of χ ₁ and χ ₂ to the data. If the amount of reflected light from the shield is obtained in this way, the true amount of reflected light from the reflector 2 can be obtained by calculating the difference between the amount of received light and the amount of reflected light when the fire monitoring light emitting element 10 is turned on. .. Then, the fire determination unit 19 compares the value with a threshold value set in advance in the threshold value setting unit 18 to make a fire determination.

The series of calculations are carried out each time the light emitting elements 10 and 30 are intermittently turned on. That is,
Fire judgment is made by comparing with the immediately preceding data. Therefore, even if the number of shields is newly increased or the amount of light reflected by the shield changes, accurate fire determination can be performed.

FIG. 5 is a perspective view showing the sensor body 1 of the second embodiment according to the present invention. In the case of this embodiment, two light emitting elements are provided in the previous embodiment, whereas two light receiving elements are provided. The structure of the sensor body 1 of this embodiment is almost the same as that of the first embodiment shown in FIG. 2, and the light receiving element 13 is different from that of the first embodiment.
Instead, two light receiving elements are provided, a fire monitoring light receiving element 53 and a shield monitoring light receiving element 54, and there is only one light emitting element (light emitting element 50). Also,
In this case, the switching control unit 32 switches which light receiving element receives light and which data storage unit receives the received light data.

In this embodiment, the light emitting element 50 is turned on intermittently. 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. Further, almost no reflected light from the reflection plate 2 is incident on the shielding object monitoring light receiving element 54. Then, the ratio of the amount of incident light is the first
The distance between the light receiving elements 53 and 54 and the light emitting element 50 is set so as to have a predetermined value, as in the above embodiment.

Therefore, also in this embodiment, as in the first embodiment, the amount of light reflected by the shield is obtained by solving the simultaneous equations in the arithmetic unit 39 based on the obtained data, and the true amount of reflected light is calculated from this. The fire determination is made by determining and comparing with the threshold value in the fire determination unit 19.

[0029]

As described above, according to the first aspect of the present invention, the fire monitoring light emitting section is arranged close to the light receiving section,
The shielding object monitoring light emitting unit is arranged at a position distant from the light receiving unit, and these are alternately turned on and lighted, and a predetermined calculation is performed based on the received light amount to obtain the amount of light reflected by the shielding object. There is an effect that the influence of the shield can be canceled and the true amount of reflected light from the reflector can be obtained. As a result, accurate fire determination can be performed even when the shield is in the monitoring area.

According to the present invention of claim 2, the fire monitoring light receiving section is arranged in the vicinity of the light emitting section, while the shield monitoring light receiving section is arranged at a position distant from the light receiving section. By alternately receiving the reflected light by, and calculating the amount of light reflected by the shield by performing a predetermined calculation based on the amount of received light, it is possible to cancel the influence of the shield on the amount of received light, and There is an effect that the amount of reflected light can be obtained. As a result, accurate fire determination can be performed even when the shield is in the monitoring area.

[Brief description of drawings]

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

FIG. 2 is a configuration block diagram of a sensor 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 reflecting plate 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 body type smoke detector according to a second embodiment of the present invention on a detector body side.

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

[Explanation of symbols]

 1 Sensor main body 2 Reflector 4 Light emitting part 5 Light receiving part 6 Judging part 9 Shielding object 10 Fire monitoring light emitting element 13 Light receiving element 30 Shielding object monitoring light emitting element 39 Calculation part 50 Light emitting element 53 Fire monitoring light receiving element 54 Shielding object Light receiving element for monitoring

Claims (2)

[Claims] 1. A fire monitoring light emitting section for emitting a light beam to a reflecting plate arranged at a fixed distance, a light receiving section for receiving reflected light from the reflecting plate, and a light receiving output of the light receiving section in advance. In a photoelectric separated smoke detector equipped with a judgment unit that makes a detection output when it is less than or equal to a set threshold value, the fire is located at a position off the optical axis connecting the fire monitoring light-emitting unit with the reflector and light-receiving unit. A light emitting unit for shielding objects arranged at a predetermined distance from the light emitting unit for monitoring is provided, and the light emitting unit for fire monitoring and the light emitting unit for shielding object are alternately turned on to turn on the light emitting unit for fire monitoring. And the amount of light received when the shield monitoring light emitting unit is lit, and the amount of light received when the fire monitoring light emitting unit is lit and when the shield monitoring light emitting unit is lit when a predetermined shield does not exist. 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 section which emits a light beam to a reflecting plate arranged at a certain distance, a fire monitoring light receiving section which receives reflected light from the reflecting plate, and a light receiving section of the fire monitoring light receiving section. In a photoelectric separated smoke detector including a determination unit that performs a detection output when the output is less than or equal to a preset threshold value, a position deviated from the optical axis connecting the light emitting unit, the reflector, and the fire monitoring light receiving unit. Has a shielding object monitoring light receiving part disposed at a predetermined distance from the fire monitoring light receiving part, the light emitting part is intermittently turned on, and the fire monitoring light receiving part and the shielding object monitoring light receiving part alternate with each other. And the amount of light received when the fire monitoring light receiving unit is received, the amount of light received when the shield monitoring light receiving unit is received, and when the fire monitoring light receiving unit is received when there is no predetermined shield. Amount of light received when receiving light from the shield monitoring The photoelectric separation type smoke characterized in that the fire is judged by obtaining 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 at the time of receiving light for fire monitoring with the above threshold value. sensor.