JP3233985B2 - 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. 5A shows a schematic configuration of a conventional photoelectric separation type smoke detector. As can be seen from FIG. 5 (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 to form a light beam 106 and traverses 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. 5 (b), when a shield 121 other than smoke is present in a monitoring area in a normal monitoring state, a light receiving output on a light receiving section side is provided. 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, other shields such as pipes and ducts are often placed near the ceiling of the building, and if these shields are within the so-called limit radius, to avoid false alarms due to the reflected light However, there is also a problem that the sensor cannot be installed even though the sensor is effective.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it has been proposed that smoke and piping other than smoke in a monitoring area be provided.
The presence of obstacle, such as ducting can accurately determine, and distribution
Regardless of the reflectance of shields such as pipes and ducts, we provide a photoelectric-separated smoke detector that can make an accurate fire judgment by canceling out the influence and obtaining the true reflected light amount from the reflector. The purpose is to do.

[0008]

According to a first aspect of the present invention, there is provided a photoelectric separation type smoke detector for emitting a light beam to a reflector disposed at a predetermined distance from a reflector. In a photoelectric separation type smoke detector including a light receiving unit that receives light reflected from the reflector and a determination unit that makes a fire determination based on the light reception output of the light receiver , the photoelectric separation smoke detector is disposed in front of the reflector. Providing a low-reflectance light-shielding means for shielding incident light from the light-emitting portion with respect to the reflector for a predetermined time, comparing the amount of light received when the reflector is shielded and the amount of light received when the reflector is exposed, and the difference is determined. The configuration is such that a fire determination is made when the value falls below a preset threshold .

According to a second aspect of the present invention, the light-shielding means is a chopper that includes a low-reflectance rotating blade and shields the front surface of the reflector for a predetermined time by rotation of the rotary blade. The electronic shutter is configured to block the front surface of the reflection plate for a predetermined time by being in a transparent or light-shielded state.

[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 addition, the present invention particularly has a configuration in which a chopper 3 made of a rotating wing is provided on the front surface of the reflection plate 2.

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 light-emitting element 10 such as a light-emitting diode that emits near-infrared light, a light-emitting drive unit 11 that drives the light-emitting element 10, and a light-receiving and light-emitting control unit 12 that controls light emission and light reception. It is configured.

Next, the light receiving section 5 includes a light receiving element 13 for receiving the light reflected by the reflector 2, an amplifier circuit 15 for amplifying the output from the light receiving element 13, and an analog signal from the amplifier circuit 15 for converting a digital signal into a digital signal. An A / D converter 16 converts the received light data.

The determining unit 6 determines that the chopper 3 is
Data storage unit 17 for storing the received light data when the reflector 2 is exposed without blocking the light, a received light data storage unit 37 for storing the received light data when the reflection plate 2 is blocked, and both the received light data storage units 17 and 37 It comprises a comparison judging section 39 for taking out and comparing data, a threshold setting section 18 for setting a threshold for making a fire judgment in advance, and a fire judging section 19 for making a fire judgment based on the threshold and data from the comparison judging section 39. .

Further, in the present embodiment, a changeover switch 34 for switching the received light data in synchronization with the rotation of the chopper 3, a changeover control unit 32 for controlling the rotation of the chopper 3 and the changeover operation of the changeover switch 34, and A timer 33 for performing time management is also provided. That is,
By these operations, the storage location of the received light data is changed depending on whether or not the chopper 3 blocks the reflection plate 2.

In the present embodiment, a collimating lens 51 for collimating light is provided on the front surface of the light emitting element 10, and a condensing light for condensing the reflected light from the reflector 2 on the front surface of the light receiving element 13. A lens 52 is provided.

On the other hand, in this embodiment, a reflector 2 and a chopper 3 are provided in addition to the sensor main body 1 as shown in FIG. Here, the reflector 2 uses a so-called retroreflective mirror, and the light emitted from the light emitting element 10 of the sensor main body 1 is collimated by the collimating lens 51 and changes its direction by 180 ° by the reflector 2 to receive light of the sensor main body 1. Return to part 5.

The chopper 3 is provided on the front surface of the reflection plate 2 on the sensor body 1 side. The chopper 3 is a propeller-shaped one provided with a rotating blade 3a having a low reflectance, and has a configuration in which the front surface of the reflecting plate 2 is blocked by its rotation. Therefore, when the rotor blades 3a of the chopper 3 is in a position to block the light from the light emitting element 10 a front of the reflector 2, light from the light emitting element 10 is not incident on the reflection plate 2, rotated further The light from the light emitting element 10 does not return to the light receiving element 13 because the reflectance of the wing 3a is low. The rotation of the chopper 3 is controlled by the switching control unit 32 because it is necessary to synchronize with the switching of the received light data.

Next, the operation of the first embodiment configured as described above will be described with reference to FIG. (A), (b),
(C) and (d) show the received light data (data based only on the reflected light of the reflector 2) in normal times (with no smoke and no shielding), and in the case where there are shieldings such as pipes and ducts . receiving data of the reflected light only the shield 9, such as the piping and ducting, when actually obtained received data when there is an interrupting object 9 such as piping and ducting and the there is an interrupting object and smoke, occurs This shows the state of the received light data.

Normally, only light reflected by the light emitting element 10 is received by the light receiving element 13. Accordingly, as the chopper 3 rotates, the amount of received light changes intermittently as shown in FIG. In this case, the light emitting element 1
The light emission of 0 may be either continuous lighting or pulsed light emission synchronized with the rotation of the chopper 3 .
Therefore, in FIG. 3, the light emission of the light emitting element 10 is described as continuous lighting.
I do. Next, pipes and ducts in the monitoring area as shown in Figure 1
It is assumed that there is a shield 9 such as a bird . In this case, the reflected light from the shield 9 such as a pipe or a duct is shown in FIG.
It shows a constant value (N) as shown in FIG. Therefore, the data actually obtained when the shield 9 is present is in the form of S + N obtained by adding FIGS. 3A and 3B as shown in FIG.

In the present invention, a difference between the data obtained as shown in FIG. Specifically, the data when the chopper 3 blocks the reflector 2 is
The received light data is stored in the received light data storage unit 17. On the other hand, data when the reflection plate 2 is exposed without being blocked is stored in the light reception data storage unit 37. Next, the difference between these data is obtained in the call comparison / judgment section 39. That is,
The value of S in FIG. 3C is obtained. Then, the fire judgment unit 19 makes a fire judgment by comparing the difference with a threshold value.

Here, consider a case where smoke has entered the monitoring area due to the occurrence of a fire. At this time, the light from the light emitting element 10 is scattered by the smoke particles, and the amount of light received by the light receiving element 13 is smaller than usual. Figure 3 shows this situation.
(D). In FIG. 3D, the explanation is simplified.
The constant value (N) is kept constant with the invasion of smoke
However, of course, the constant value (N) relatively decreases due to the intrusion of smoke.
You. That is, due to the invasion of smoke, the difference in the amount of received light decreases from the difference S ₀ in the normal case to S ₁ . Therefore, the threshold is set to _St
Fire determination portion 19 _{when S 1} is lower than the _{S t} When
Judges that a fire has occurred. Also in this case, in this embodiment, the effect of the shielding object is canceled because the difference between the immediately preceding data is always compared with the threshold value. In addition, even when the number of shields further increases, the chopper 3
The data when the reflector 2 is blocked and the chopper 3
In the case of the present invention, in which a fire judgment is made after comparing data in the case of exposure without interfering with block 2, the effect is canceled each time . Therefore, even if the number of shielding objects 9 such as pipes and ducts increases, no alarm is generated due to the increase, and no false alarm is generated even when the amount of received light is reduced due to contamination of the lens . When detecting reflected light (N) from a shield 9 such as a pipe or a duct, a trouble signal is generated and a pipe is issued.
Needless to say, the presence of a shield such as a wall or a duct may be notified.

Next, a second embodiment according to the present invention will be described with reference to FIG. FIG. 4 is a perspective view illustrating the configuration of the present embodiment. In this case, since the sensor body 1 is the same as that of the first embodiment, only the reflection plate 2 side is shown. In this embodiment,
Electronic shutter 7 instead of chopper 3 of the first embodiment
Is used. That is, the same operation as that of the first embodiment is realized by setting the electronic shutter 7 to be transparent (FIG. 4A) or light-shielded state (FIG. 4B).

In this embodiment, the structure of the sensor main body 1 and the reflection plate 2 are the same as in the first embodiment. In this embodiment,
It is characterized in that an electronic shutter 7 is arranged on the front surface of the reflection plate 2. As the electronic shutter 7, a commercially available electronic shutter such as one using liquid crystal is used. However, it is necessary that the surface has a low reflectance. The operation of the electronic shutter 7 is controlled by the switching control unit 32 as in the case of the above-described chopper 3, and the received light data is stored in synchronization therewith, and comparison and judgment are performed. The method of fire determination in that case is the same as in the first embodiment.

[0025]

As described above, according to the present invention, a light-shielding means having a low reflectance is provided on the front surface of a reflector, and the light-receiving amount from the reflector is periodically changed by periodically operating the light-shielding means. By taking the difference between the amount of light received when the reflector is shielded and the amount of light received during exposure, the effect of the shield on the amount of light received can be offset, and the true amount of reflected light from the reflector can be determined. There is an effect that can be. In other words, accurate fire determination can be performed even when a shield such as a pipe or a duct is in the monitoring area.

According to the second and third aspects of the present invention, there is an effect that the above effects can be achieved with a simple device.

[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 a timing chart showing a state of a received light amount in the photoelectric separation type smoke sensor according to the first embodiment of the present invention.

FIG. 4 is a perspective view showing a configuration on a reflector side of a photoelectric separation type smoke detector according to a second embodiment of the present invention.

FIG. 5 is an explanatory view showing an example of a conventional photoelectric separation type smoke detector.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sensor main body 2 Reflector 3 Chopper 3a Rotor 4 Light emitting part 5 Light receiving part 6 Judgment part 7 Electronic shutter

Claims (3)

(57) [Claims] 1. A light emitting unit that emits a light beam to a reflector disposed at a fixed distance, a light receiver that receives light reflected from the reflector, and a fire detector based on a light output of the light receiver.
In the photoelectric separation type smoke sensor including a determination unit for performing a disconnection , a low-reflectance light shielding unit that is disposed on the front surface of the reflection plate and blocks incident light from the light emitting unit with respect to the reflection plate for a predetermined time is provided. Provided, comparing the amount of light received when the reflector is shielded and the amount of light received when the reflector is exposed, and the difference is set to be equal to or less than a preset threshold.
A photoelectric-separated smoke detector characterized in that a fire judgment is made in the event of fire. 2. The photoelectric device according to claim 1, wherein the light-shielding means is a chopper that includes a low-reflectance rotating blade, and blocks the front surface of the reflector for a predetermined time by rotation of the rotating blade. Separate smoke detector. 3. The photoelectric separation type smoke sensor according to claim 1, wherein said light shielding means is an electronic shutter for shielding a front surface of said reflection plate for a predetermined time by making it transparent or in a light shielding state. .