JP6546314B2 - Fire detection system and fire detection method - Google Patents

Description

  The present invention relates to a fire detection system and a fire detection method for detecting smoke in an early stage of a fire from an image of a monitoring area captured by a monitoring camera.

  Conventionally, various fire detection systems have been proposed in which a fire is detected by performing image processing on an image of a monitoring area captured by a monitoring camera.

  In such a fire detection system, early detection of a fire is important from the viewpoint of initial fire extinguishing and evacuation guidance for fire occurrence.

  For this reason, in the conventional system (Patent Document 1), as a phenomenon caused by smoke from a fire from an image, the transmittance or contrast decreases, the brightness value converges to a specific value, the brightness distribution range narrows and the brightness distribution It is possible to detect smoke by comprehensively determining the decrease in the brightness, the change in the average value of the brightness due to smoke, the decrease in the total amount of edges, and the increase in intensity in the low frequency band.

JP, 2008-046916, A Unexamined-Japanese-Patent No. 7-245757 JP, 2010-238028, A JP 2004-325211 A JP 2004-104727 A JP, 2006-085608, A

  However, in a fire detection system that detects a fire from an image of smoke associated with such a conventional fire, smoke from a small fire near a surveillance camera and smoke from a large fire can not be identified. For a fire that has occurred in a distance, there is a problem that the detection sensitivity is lowered and the time delay until the fire is detected becomes large. On the contrary, the smoke by the non-fire phenomenon generated near the surveillance camera is misrecognized as the smoke by the fire. For example, cigarette smoke smoked in the immediate vicinity of a surveillance camera may be misrecognized as smoke from a large fire located far away.

  The present invention combines a first-stage fire detection from a light-reduced image with smoke and a fire detection from a light-scattered light image with smoke to reliably detect a fire of a certain size, and a fire detection system and fire It aims to provide a detection method.

(system)
The present invention relates to a fire detection system
Imaging means for imaging a monitoring area to be a partition space;
Background illumination means for illuminating the background of the monitoring area to be imaged by the imaging means with constant illumination and background;
General illumination means for overall illumination of the monitoring area imaged by the imaging means;
First fire detection means for detecting a first-stage fire from a dimmed image of a smoke plume generated in the monitoring area captured by the imaging means and outputting a first fire signal, with the monitoring area illuminated in the background;
Illumination switching means for stopping background illumination by the background illumination means and switching to overall illumination by the overall illumination means when the first fire detection means detects a first stage fire;
The second fire signal is output by detecting a second fire from the scattered light image of the smoke plume generated in the monitoring area captured by the imaging unit in a state in which the monitoring area is switched to the entire illumination by the illumination switching unit Fire detection means,
Is provided.

  Here, the plume of smoke is a cylindrical smoke range formed as the smoke rises with the combustion, and has a rising speed and a thickness corresponding to the size of the fire source.

  In addition, the fire of the first stage and the fire of the second stage are the notation to distinguish the fire detection by the first fire detection means and the fire detection by the second fire detection means, and represent the scale and condition of the fire Absent.

(Method)
The present invention relates to a fire detection method.
The first fire signal is detected by detecting a fire at the first stage from a dimmed image of the smoke plume generated in the monitoring area captured by the imaging unit in a state in which the background of the monitoring area forming the partition space is illuminated with constant illumination. The first fire detection step to output;
When the first fire detection step detects a fire at the first stage, the scattered light image of the smoke plume generated in the monitoring area captured by the imaging unit with the background illumination stopped and the monitoring area switched to the overall illumination A second fire detection step of detecting a second fire from the second fire and outputting a second fire signal,
Is provided.

  The other features of the fire detection method according to the invention are basically the same as in the case of the fire detection system.

(Basic effect)
The fire detection system according to the present invention comprises an imaging means for imaging a monitoring area to be a partition space, background illumination means for illuminating a wall surface and a floor surface as a background of the monitoring area to be imaged by the imaging means with constant illuminance, The first stage fire is detected from the dimmed image of the smoke plume generated in the monitoring area captured by the imaging means, with the entire illumination means illuminating the entire monitoring area to be imaged and the background illumination of the monitoring area 1) The first fire detection means that outputs a fire signal, and the light switch that stops the background lighting by the background lighting means and switches to the general lighting by the whole lighting means when the first fire detection means detects a fire at the first stage The second stage fire from the scattered light image of the smoke plume generated in the monitoring area captured by the imaging unit in a state where the monitoring area is switched to the entire illumination by the unit and the illumination switching unit Since the second fire detection means for detecting and outputting the second fire signal is provided, the first fire is detected based on a light reduction image in which the light from the background light is reduced by the smoke plume. (1) In order to output a fire signal to notify a fire alarm (pre-alarm) and to confirm the fire, switch the illumination of the monitoring area from the background illumination to the general illumination and scatter the smoke by the general illumination scattered by the smoke plume Even if it is an image of the smoke plume whose size changes with distance by outputting the second fire signal and notifying the fire alarm when the second stage fire is detected from the light image, the dimmed image and the scattering By combining fire detection based on different observation images of the light image, it is possible to reliably detect and warn a fire from the observation image of the monitoring area captured by the imaging means.

  In addition, since the lighting switching control means switches from background lighting in the monitoring area to overall lighting when it determines the fire in the first stage, it illuminates the entire room as the monitoring area when it determines the fire in the first stage. By being able to pick up an image, it is possible to confirm artificially by looking at the monitor screen etc., and to be able to appropriately cope with fire fighting and evacuation activities.

  Also, even if the first stage fire is erroneously detected from the dimmed image of the smoke plume because the light from the background illumination is temporarily blocked by an object other than smoke, for example, a person, the first stage fire detection Based on the scattered light image captured by switching to the overall illumination of the surveillance area based on the brightness ratio is different from smoke, the thickness of the smoke plume does not exceed the threshold for determining fire, and false notification due to non-fire cause Can be prevented.

Explanatory drawing which showed the monitoring area | region which installed the fire detection system of this invention Block diagram showing an embodiment of a fire detection system according to the invention Explanatory drawing which modeled and showed smoke generated by fire Graph showing the relationship between smoke plume thickness and light reduction rate to heat source heat quantity An explanatory drawing showing a model fire for finding an experimental formula of ceiling flow by Alpert Graph showing the relationship between smoke plume thickness and light reduction rate determined based on Fig. 4 A graph showing the relationship between the distance to the background and the energy and area of the background illuminated with constant illumination A graph showing the relationship between the rate of light reduction and the rate of smoke ascent to the height of the smoke plume Explanatory drawing which showed the relationship between the view angle of a smoke plume and the flame distance about the horizontal surveillance area | region of a surveillance camera Explanatory drawing which showed the image processing which produces | generates and determines a sub image by the 1st smoke image determination part of FIG. Graph showing the relationship between smoke plume thickness and total brightness and smoke concentration Graph showing the relationship between smoke plume thickness and luminance factor and smoke concentration A graph showing the relationship between the total brightness and the brightness rate against the distance to the fire point A flowchart showing an outline of fire detection processing by the image processing apparatus of FIG. 2 The flowchart which showed the detail of the 1st fire detection processing of S2 in Figure 14 The flowchart which showed the detail of the 2nd fire detection processing of S6 in Figure 14

[Outline of fire detection system]
(Overview of monitoring area)
FIG. 1 is an explanatory view showing a monitoring area in which a fire detection system according to the present invention is installed.

  As shown in FIG. 1, the monitoring area 16 is a partition space such as a room, and the monitoring area 10 is provided with a monitoring camera 10 which functions as an imaging unit. An observation image of the monitoring area 16 captured by the monitoring camera 10 is transmitted to an image processing apparatus 12 installed in a manager's office or the like via a transmission path.

(Schematic configuration of fire detection system)
FIG. 2 is a block diagram schematically showing the functional configuration of the fire detection system according to the present invention. As shown in FIG. 2, the fire detection system includes the monitoring camera 10 and the image processing apparatus 12, and the image processing apparatus 12 includes a computer circuit including a CPU, a memory, various input / output ports and the like as its hardware. Composed of

  The image processing apparatus 12 has a transmission unit 28, a first fire detection unit 50 that functions as a first fire detection unit, and a second fire detection unit that functions as a second fire detection unit as functions realized by the execution of a program by the CPU. And an illumination switching unit functioning as illumination switching means.

  The first fire detection unit 50 functions as a first smoke image determination unit 30 functioning as a first smoke image determination unit, a first appearance angle detection unit 32 functioning as a first appearance angle detection unit, and a light reduction rate detection unit Attenuation rate detection unit 34, a first plume thickness estimation unit 36 functioning as a first plume thickness estimation unit, a first distance calculation unit 38 functioning as a first distance calculation unit, and a first fire determination unit A first fire determination unit 40 is provided. In addition, although the illumination switching part 42 is included in the function of the 1st fire determination part 40, you may provide as an independent function. Further, the transmission unit 28 uses an appropriate transmission interface for receiving image data captured by the monitoring camera 10.

  The second fire detection unit 100 functions as a second smoke image determination unit 130 that functions as a second smoke image determination unit, a second appearance angle detection unit 132 that functions as a second appearance angle detection unit, and a brightness ratio detection unit A luminance ratio detecting unit 134, a second plume thickness estimating unit 136 functioning as a second plume thickness estimating unit, a second distance calculating unit 138 functioning as a second distance calculating unit, and a second functioning as a second fire determining unit A fire determination unit 140 is provided.

  The monitoring camera 10 functioning as an imaging unit transmits image data of a monitoring area of, for example, 30 frames per second as moving image data under transmission control of the transmission unit 28 and stores it in a memory (not shown) provided in the image processing apparatus 12 . In this embodiment, for example, a surveillance camera 10 having a resolution of 1400 horizontal pixels and 1000 vertical pixels is used. The detection wavelength of the surveillance camera 10 is set to 750 nm or more in consideration of background illumination by infrared light.

  For example, taking the fire monitoring of the monitoring area which has become unmanned by setting the monitoring mode at night, for example, the lighting switching unit 42 turns off the indoor lighting device 24 by automatic setting or manual setting of the monitoring mode by timer setting. At the same time, the floor illumination device 22a and the wall illumination device 22b are always lit or pulse lit, and only the background floor and wall as background are illuminated with constant illumination by indirect illumination.

  Here, the floor surface lighting device 22a and the wall surface lighting device 22b constitute background lighting means, and the indoor lighting device 24 constitutes whole lighting means.

  The first fire detection unit 50 reduces the light reduction rate from the light reduction image of the smoke plume generated in the monitoring area captured by the monitoring camera 10 in a state in which the monitoring area 16 is background illuminated by the floor lighting device 22a and the wall lighting device 22b. To determine the thickness of the smoke plume from the light reduction rate, detect a first-stage fire, and output a first fire signal, for example, a fire alarm (pre-alarm) from the fire alarm system 14 of FIG. Make it output.

  When the first fire detection unit 50 detects a fire at the first stage, the lighting switching unit 42 stops background lighting by the floor lighting device 22a and the wall lighting device 22b and switches to general lighting by the indoor lighting device 24. .

  The second fire detection unit 100 obtains the luminance ratio from the scattered light image of the smoke plume generated in the monitoring area captured by the monitoring camera 10 in a state where the monitoring area 16 is switched to the entire illumination by the illumination switching unit 42 Based on the above, the thickness of the smoke plume is estimated, the second stage fire is detected, and a second fire signal is output. For example, a fire alarm is output from the fire alarm system 14 following the fire alarm.

(Lighting of surveillance area)
In order to correctly detect the light reduction rate by smoke of the monitoring area 16 from the observation image of the monitoring camera 10 by the first fire detection unit 50, only the floor surface 16a, the wall surface 16b and the ceiling surface 16c serving as the background emit light It is desirable to use background lighting that does not illuminate the smoke that spreads over.

  For this reason, in the present embodiment, the floor surface illumination device 22a and the wall surface illumination device 22b as illumination means for illuminating the floor surface 16a and the wall surface 16b as the background of the monitoring area 16 imaged by the monitoring camera 10 with constant illuminance. Indirect lighting is installed.

  The floor lighting device 22a and the wall lighting device 22b are provided with a reflective hood, and emit light from the light source toward the floor surface 16a and the wall surface 16b so that the light does not go into the space of the monitoring area. Moreover, the floor surface illumination device 22a and the wall surface illumination device 22b use a light source of visible light or infrared light, and illuminate the floor surface 16a and the wall surface 16b with constant illuminance by constant lighting or intermittent lighting (pulse lighting). .

  The room lighting device 24 is provided on the ceiling surface 16c of the monitoring area, and during the daytime or the like, the room lighting device 24 is turned on to illuminate the entire monitoring area during a person's room such as daytime. When the fire of the monitoring area 16 is monitored by the monitoring camera 10 unmanned at night, etc., the indoor lighting device 24 is turned off and the floor lighting device 22a and the wall lighting device 22b are turned on.

  In the case where a fire is monitored by the monitoring camera 10 in a state in which the indoor lighting device 24 is on while the person is in the room, the illumination light of the indoor lighting device 24 is made visible light that does not contain near infrared light; The illumination light of the floor illumination device 22a and the wall illumination device 22b may be near infrared light. In this case, the sensing wavelengths of the surveillance camera 10 include near infrared wavelengths illuminating the floor surface 16 a and the wall surface 16 b.

  The fluorescent light and LED lighting fixtures generally used as the indoor lighting device 24 have small irradiation energy of near infrared light of 750 nm or more, and the detection wavelength of the monitoring camera 10 is 750 nm or more. By making the light source of the device 22 b an infrared LED or a heat generating lamp, the floor surface 16 a and the wall surface 16 b serving as the background of the monitoring area by the monitoring camera 10 have a constant illuminance by infrared light that is not affected by visible light from the indoor lighting device 24. Makes it possible to emit light.

  It should be noted that instead of illuminating the surveillance area 16 imaged by the surveillance camera 10 with a background, a light emitting panel with an infrared illumination structure embedded in the back, a face panel with a fluorescent paint applied to convert visible light to near infrared light, etc. It is also possible to obtain a constant illuminance.

  On the other hand, in order to correctly detect the luminance rate from the scattered light by smoke of the monitoring area 16 from the observation image of the monitoring camera 10 in the second fire detection unit 100, switching to overall lighting by the indoor lighting device 24 and rising in the monitoring area 16 The smoke 20 is hit by the light from the indoor lighting devices 24 and so on so that scattered light from the smoke particles can be obtained.

[Detection principle by reduced light image of smoke plume]
The first fire detection unit 50 in FIG. 2 detects a fire at the first stage from a dimmed image of the smoke plume generated in the monitoring area captured by the monitoring camera 10 with the monitoring area 16 illuminated in the background. The detection principle will be described as follows.

(Smoke plume and dimming rate)
FIG. 3: is explanatory drawing which modeled and showed the smoke which generate | occur | produces by fire, as shown in FIG.

  As shown in FIG. 3, in the early stage of the fire, the smoke plume 26 which becomes a cylindrical smoke range is formed as the smoke rises, and the thickness 2 r (radius r) of the smoke plume 26 is considered to be substantially constant. Be In the following description, the smoke plume may be simply referred to as the plume.

  When the floor surface 16a and the wall surface 16b which are the background of the monitoring area 16 imaged by the surveillance camera 10 shown in FIG. 1 are illuminated with constant illuminance, the surveillance camera 10 captures a dimmed image by the smoke 20 generated. It is possible to detect the rate of light reduction by the smoke plume.

  Now, let us consider a fire model in which paper burns and spreads gradually. In this case, the thickness of the smoke plume 26 gradually increases with the spread of the fire, and at the same time the smoke plume 26 also becomes thick and the light reduction rate increases.

  Fig. 4 shows the thickness 2r (m) of the smoke plume at the point of height H = 1m, the extinction ratio y (% / m) and the smoke rising velocity u (m It is the graph which showed the relationship of / s). The light reduction rate y (% / m) means smoke concentration.

  The smoke plume generated by the fire becomes thicker as the amount of heat is increased due to the expansion of the fire source, and at the same time the rate of rise u (m / s) and the rate of extinction y (% / m) of the smoke also increase.

(Experience formula of Alpert)
The plume thickness and smoke concentration (darkening rate) for each height in the smoke plume generated by the fire can be obtained by an empirical formula of Alpart. This Alpert's experimental formula is the 76th paper in the National Fire Protection Association's annual meeting held on May 18, 1972 in the United States, Philadelphia, "Calculating the Time Response of a Ceiling-Mounted Fire Detector ( It is announced in "Calculation of Response Time of Ceiling-Mounted Fire Detectors".

  FIG. 5A is an explanatory view showing a model fire in which an experimental formula of a ceiling flow by Alpert is obtained.

Assuming that the heat generation amount of the fire point is Q (kW), the temperature rise ΔT and the wind speed u are as follows.
ΔT = 5.38 (Q / r) 2/3 / H
u = 0.2Q1 / 3H1 / 2 / r5 / 6
The relationship between the height H of the plume and the radius r and the light reduction rate y is determined. The relationship between the smoke extinction coefficient k (1 / m) and the temperature rise ΔT is determined by the substance to be burned, and considering the case where the paper burns,
k / ΔT = 0.41E-2 (1 / m · deg)
It becomes. To convert the extinction coefficient k (1 / m) to the attenuation rate y (% / m) y = (1-e-k) · 100
It becomes. FIG. 5B shows representative values of the k / ΔT ratio.

  According to the above relational expression, when the combustion product is paper, the thickness 2r (m) at the height H of the smoke plume due to the fire due to the fire where the heat generation amount Q gradually increases, the extinction ratio y (% / m), If the rising wind speed u (m / sec) is determined, the relationship shown in the graph of FIG. 6 is obtained.

  FIG. 6 is a graph showing the relationship between the smoke plume thickness and the smoke concentration obtained based on the graph of FIG. In FIG. 6, when the light from the background passes through the smoke plume with a thickness of 2r (m) having a light reduction rate y (% / m) corresponding to the thickness of the smoke plume, the light reduction rate Y It is shown by asking for (%). The light reduction rate detected from the observation image of the monitoring area 16 in which the smoke 20 is captured by the monitoring camera 10 of FIG. 1 is the light reduction rate Y (%) of the smoke plume of FIG.

  Here, the light reduction rate Y (%) of the smoke plume detected from the observation image of the monitoring camera 10 is constant regardless of the fire point distance L from the fire point 18 to the monitoring camera 10. This is based on the fact that the energy entering the surveillance camera 10 from the background where uniform light strikes is constant regardless of the distance to the background.

  FIG. 7 is a graph showing the relationship between the distance to the background and the energy and area of the background illuminated at a constant illuminance.

Now, assuming that the distance from the monitoring camera 10 to the background is L0 and the viewing angle of the monitoring camera 10 is θ, the area S (m 2) of the background serving as the viewing area of the monitoring camera 10 is
S = (L0 · tan θ) 2
It becomes.

Also, assuming that the uniform light strikes the background and the luminance ratio of the reflected light emitted from the background is W (mW / m 2), the radiation intensity E (mW) emitted from the background within the field of view of the surveillance camera 10 is E = W · S = W (L0 · tan θ) 2
It becomes.

The energy Er (mW) of this background light entering the surveillance camera 10 separated by L0 is inversely proportional to the square of the distance L0. Incident energy at different distances L01 and L02 to the background: Er1 and Er2 are Er2 / Er1 = L022 / L012
Er2 = Er1 · L022 / L012
= W (L01 · tan θ) 2 · L022 / L012
= W (L 02 · tan θ) 2
= Er2
That is, the energy Er incident on the surveillance camera 10 from the background on which uniform light strikes is constant regardless of the distance L to the background.

When a smoke layer of a smoke plume with a light reduction rate (1-α) intervenes in the path of this light, the energy Es transmitted through the smoke layer and incident on the surveillance camera 10 is
Es = (1-α) Er
The incident energy Es of the surveillance camera 10 is constant regardless of the distance from the smoke layer to the surveillance camera 10.

  From the above relationship, as shown in FIG. 6, in the case of background lighting in which the illuminance to the background floor surface 16a and the wall surface 16b is constant, the light reduction ratio Y (%) by the smoke 20 is the background It can be uniquely determined regardless of the distance Lo to the light and the fire point distance L to the smoke 20.

(Relationship of light reduction rate and thickness by height of smoke plume)
The relationship between the thickness of the smoke plume and the light reduction rate for each height of the smoke plume generated by the fire can be obtained by the Alpert theory shown in FIG. 5 as described above. Now, assuming that paper is a burned material, the relationship between plume radius r, light reduction rate y and smoke rising rate u for each height H of the plume generated from an initial fire with a heat quantity of 30 kW is calculated as shown in It becomes as shown in the graph.

  As shown in FIG. 8, the smoke plume generated by the fire involves the surrounding air, and as the height H becomes higher, the smoke plume radius r becomes thicker and the light reduction rate y becomes lower.

  Therefore, it is desirable to detect the light reduction rate by the relatively low part of the smoke plume, and in the present embodiment, H = 1.0 m is set in the model fire assumed to determine the fire.

  Further, in FIG. 1, it is desirable to set the optical axis of the monitoring camera 10 to a height of 1 meter from the floor surface 16 a. When the monitoring camera 10 is installed at the upper side and obliquely obliquely downward, the height of the optical axis on the camera side is set to, for example, 1.5 m or less.

(The relationship between smoke plume thickness and distance)
If the thickness 2r can be estimated from the dimming ratio Y of the smoke plume present in the observation image of the surveillance camera 10, the distance L from the surveillance camera 10 to the fire point generating the smoke plume can be calculated it can.

  FIG. 9 is an explanatory view showing the relationship between the smoke plume's angle of view and the fire point distance for the horizontal monitoring area of the monitoring camera.

  In order to calculate the fire point distance L, first, the perspective angle θ of the smoke plume 26 present in the observed smoke image is determined. Here, the visual angle means the angle of view when the specific object is imaged from the monitoring camera 10.

  The thickness 2r of the smoke plume 26 in the smoke image captured by the surveillance camera 10 represents the perspective angle θ of the smoke plume 26, and the distance from the surveillance camera 10 is the same even if the perspective angle θ is the same. Causes the thickness of the smoke plume 26 in the smoke image to change.

Now, assuming that the screen size of the surveillance camera 10 is (horizontal) × (vertical) = (1400 pixels) × (1000 pixels), and one side horizontal angle of the photographing area 15 of the surveillance camera 10 is 45 °, the prospect per pixel The angle α is α = 45 ° / 700 = 0.064 (° / pixel)
It becomes. In the following description, a pixel may be referred to as a pixel, and (pxl) may be described as a unit of the number of pixels.

Here, assuming that the number of pixels in the horizontal direction on the observation screen corresponding to the thickness 2r of the smoke plume captured by the surveillance camera 10 is 2R pixels, the expected angle θ of the smoke plume is
θ = α · 2R (°) (Equation 1)
It becomes.

Thus, when the prospect angle θ of the smoke plume is determined, the fire point distance L from the surveillance camera 10 to the smoke plume 26 is calculated based on the smoke plume thickness 2r obtained from the light reduction rate Y of the smoke plume
L = r / tan (θ / 2) (equation 2)
It becomes.

(Judgment of fire)
In the fire judgment by the smoke plume occupying the observation image of the surveillance camera 10, the smoke plume thickness 2r estimated from the reduction rate Y of the smoke plume is not less than the predetermined threshold fire smoke plume threshold (2r) th When it becomes, it judges as a fire.

  In this embodiment, assuming a model fire that generates smoke plumes with a thickness of 2r = 0.6 (m) at a light reduction rate Y = 48 (%), the threshold thickness (2r) of the smoke plume determined to be a fire Th = 0.6 (m) is set, and when it becomes more than threshold thickness (2r) th, it determines with a fire, and when it is less than it, it determines with a non fire.

(Functional configuration of the first fire detection unit)
As shown in FIG. 2, the fire detection system includes the monitoring camera 10 and the image processing device 12, and the image processing device 12 is provided with a first fire detection unit 50 following the transmission unit 28.

  While the first fire detection unit 50 turns off the indoor lighting device 24 and lights the floor lighting device 22a and the wall lighting device 22b, the first fire detection unit 50 illuminates only the background floor and wall with indirect illumination with constant illumination. It operates and transmits image data of a monitoring area of, for example, 30 frames per second as moving image data captured by the monitoring camera 10 under the transmission control of the transmission unit 28 and stores the image data in a memory (not shown) provided in the image processing apparatus 12.

  The first smoke image determination unit 30 determines a smoke image in which a smoke plume is present from the image captured by the monitoring camera 10. For example, as shown in FIG. 10, the first smoke image determining unit 30 determines the smoke image by storing an observation image having no smoke plume in the monitoring area captured by the monitoring camera 10 in the memory as the background image 44 The difference image 46 of the observation image 45 captured by the surveillance camera 10 and the held background image 44 is generated, and a portion in which the luminance is lower than that of the surroundings due to smoke reduction in the difference image is observed as a vertically long strip, for example The extracted area is extracted as a smoke plume area 47. When the number of pixels 2R (pxl) of the horizontal pixel row 48 of the extracted smoke plume area 47 is equal to or more than a predetermined threshold (2R) th, it is determined as a smoke image. The background image 44 is usually updated regularly.

Here, the brightness ΔB of the pixels in the smoke plume area 47 of the difference image 46 is Br, and the brightness of the corresponding pixels of the observation image 45 is Bs.
ΔB = Br-Bs
To indicate the reduction of light from the background passing through the smoke plume.

  The threshold (2R) th of the horizontal pixel number determined to be a smoke image by the first smoke image determination unit 30 generates, for example, a smoke plume of thickness 2r = 1.0 (m) at the maximum monitoring distance L = 30 (m) In this case, since the horizontal pixel number 2R of the smoke plume in the observation image is 2R = 12 pixels, the threshold (2R) th is set to (2R) th = 12 pixels.

  The first expected angle detection unit 32 calculates the expected angle θ of the smoke plume according to the equation 1 from the horizontal pixel number 2R of the smoke plume area in the smoke image determined by the first smoke image determination unit 30, and calculates the first distance Output to the section 38.

On the other hand, the light reduction rate detection unit 34 detects the light reduction rate Y at the predetermined height H of the smoke plume area in the smoke image determined by the first smoke image determination unit 30. For example, the light reduction rate detection unit 34 calculates the average brightness ΔB of the horizontal pixel row 48 of the predetermined height H of the smoke plume area 47 extracted from the difference image 46 generated by the first smoke image determination unit 30 shown in FIG. The light reduction ratio Y (%) of the smoke plume is Y = (ΔB / Br) · 100 based on the average luminance Br of the horizontal pixel column of the background image 44 at the same position as the horizontal pixel column 48.
Calculated as

Here, assuming that the average luminance of the horizontal pixel row in the observation image 45 at the same position as the horizontal pixel row 48 in the smoke plume area 47 in the difference image 46 is Bs, ΔB = (Br−Bs), and the light reduction ratio Y (Y %) Is
Y = {(Br−Bs) / Br} · 100
It means that it was calculated as

  Note that the detection of the light reduction rate Y may be calculated from the luminance of a specific pixel of the horizontal pixel column 48 of the difference image 46, for example, the center pixel, or calculated from the average luminance of a plurality of horizontal pixel columns positioned above and below It is good.

The first plume thickness estimation unit 36 estimates the thickness 2r (m) of the corresponding smoke plume from the light reduction ratio Y (%) detected by the light reduction ratio detection unit 34 based on the relationship shown in FIG. Do.
For example, the first plume thickness estimation unit 36 sets a relational expression for approximating the graph characteristics of the light reduction ratio Y and the plume thickness 2r shown in FIG. 6, and the light reduction ratio Y detected in this relational expression is By substituting, the smoke plume thickness 2r is calculated and estimated.

  Further, the first plume thickness estimation unit 36 prepares a two-way table based on the graph characteristics of the light reduction rate Y and plume thickness 2r shown in FIG. The thickness 2r of the smoke plume to be read may be read out.

  The first distance calculation unit 38 is a monitoring camera based on the equation 2 from the smoke plume perspective angle θ detected by the first prospect angle detection unit 32 and the smoke plume thickness 2 r estimated by the plume thickness estimation unit 36. Calculate the fire point distance L from 10 to the smoke plume.

  The first fire determination unit 40 determines that the first stage fire is generated when the smoke plume thickness 2r estimated by the first plume thickness estimation unit 36 is equal to or greater than a predetermined threshold (2r) th = 0.6 (m). If it is determined that there is no fire, and if it is determined that the fire is the first stage, the smoke plume thickness 2r estimated by the first plume thickness estimation unit 36 and / or the first distance calculation unit The first fire signal is output to the external fire alarm system 14 together with the data of the fire point distance L calculated at 38, and a fire alarm (pre-alarm) is output as the first stage fire alarm, for example, the thickness of the smoke plume 2r and / or the fire point distance L are displayed.

  By grasping the thickness (size) and the distance of the smoke plume in the monitoring area in such a fire alarm system 14, it is possible to appropriately grasp the situation of the first stage fire.

(A specific example of fire detection by reduced light image)
Now, assuming that the horizontal pixel number 2R of the smoke plume area determined by the first smoke image determination unit 30 is 2R = 46 pixels, the estimated angle θ calculated by the first estimated angle detection unit 32 is θ = from Equation 1 above. 0.064 × 46 = 2.94 °
It becomes.

  At this time, assuming that the light reduction ratio Y of the smoke plume detected from the smoke image by the light reduction ratio detection 34 is Y = 48 (%), the thickness 2r of the smoke plume from the relationship between the luminance ratio and plume thickness in FIG. Is estimated to be 2r = 1.0 (m).

Further, since the first distance calculation unit 38 has tan (θ / 2) = 23/700, the fire point distance L from the monitoring camera 10 to the fire point is expressed by
L = 15.2 (m)
Calculate

  The first fire determination unit 40 matches the smoke plume thickness 2r = 1.0 (m) estimated by the first plume thickness estimation unit 36 with the threshold (2r) th = 1.0 (m). Determined to be a first stage fire.

  Therefore, the first fire determination unit 40 outputs the first fire signal to the fire alarm system 14 together with the smoke plume thickness data and the fire point distance data, and outputs the first stage fire alarm and the smoke plume thickness 2r. It is possible to display the fire point distance L of 15.2 (m) and the fire state of the first stage generated in the monitoring area.

  On the other hand, even if the horizontal pixel number 2R of the smoke plume in the smoke image is 2R = 46 pixels and the prospect angle θ is the same θ = 2.94 °, the light reduction ratio Y of the smoke plume is, for example, Y = 14 (% In this case, the thickness of the smoke plume in this case is estimated to be 2r = 0.30 (m) from the relationship of FIG. 6, and the fire point distance L from the surveillance camera 10 to the fire point is It becomes = 4.6 (m).

  In this case, the thickness 2r = 0.30 (m) of the smoke plume is less than the threshold (2r) th = 1.0 (m) for determining a fire, and it is determined that the fire is not a fire.

(Relationship between smoke plume thickness and light reduction rate by burning material)
The white smoke plume generated when wood, cloth, paper, etc. is roasted maintains the same relationship between smoke plume thickness and light reduction ratio as the case of the paper shown in FIG. 6 although there are slight differences. Thus, the fire detection can be performed by the first fire detection unit 50 of FIG.

  On the other hand, when a resin such as polyurethane is burned, smoke close to black is generated. Also according to Alpert's theory, the light reduction rate of smoke generated varies depending on the type of combustion material, and the light reduction rate of smoke generated when a resin such as polyurethane or PVC is burned is when wood or paper is roasted. It is known to be quite different from white smoke.

  Therefore, by separately preparing the relationship between the light reduction rate and the thickness of the smoke plume generated when the resin such as polyurethane or PVC is burned, and setting it in the first plume thickness estimation unit 36 of FIG. A fire can be detected by estimating the thickness of the smoke plume from the detected light reduction rate.

  However, in the case of a liquid fire such as oil, for example, oil that has leaked and accumulated on the floor surface may be burned at once. In this case, a very thick plume due to a large burning area is observed with a high light reduction rate compared to wood etc., and the profile is different from that of a fire model in a smoke plume such as wood.

  Therefore, if it is determined from the size of the smoke plume area of the observation image that it is a liquid fire, the fire model must be changed. In the case of a liquid fire, the light reduction rate is larger than the observed plume thickness compared to the wood fire model fire. Also, the size of the fire source is determined by the distribution of oil and does not increase with the progress of fire like wood.

  For this reason, it is difficult to obtain the distance of the fire point from the relationship between the light reduction rate of the smoke plume and the plume thickness according to the present embodiment. Therefore, when the smoke plume area present in the difference image between the observation image of the surveillance camera and the background image is extremely large, it is determined as the first stage fire and the first fire signal is output to estimate the fire source distance. I will not.

[Detection principle of fire by scattered light image]
The second fire detection unit 100 in FIG. 2 switches the monitoring area 16 to the general illumination by the light switching unit 42 when the first fire detection unit 50 determines the fire at the first stage, and the monitoring camera 10 in this state The second fire signal is detected from the scattered light image of the smoke plume generated in the captured monitoring area and the second fire signal is output. The detection principle will be described as follows.

(Smoke plume and luminance factor)
When the monitoring area 16 shown in FIG. 1 is totally illuminated by the lighting of the interior lighting device 24, a scattered light image by the generated smoke 20 may be captured by the monitoring camera 10 to detect the occurrence of smoke plume. it can. In this case, in the observation image of the smoke 20 by the monitoring camera 10, an image corresponding to the scattered light amount in which the illumination light strikes the smoke 20 and is scattered is obtained. When the scattered light by the smoke 20 is observed by the monitoring camera 10, the amount of scattered light decreases in inverse proportion to the square of the distance L from the smoke plume.

  Now, let us consider a fire model in which wood is burned and spreads gradually. At this time, the thickness 2r of the smoke plume 26 shown in FIG. 3 becomes gradually thicker as the fire expands. At the same time, the smoke concentration y of the smoke plume also increases, thereby increasing the amount of scattered light observed. The smoke concentration y means the light reduction rate.

  FIG. 11 is a graph showing the relationship between smoke plume thickness and smoke concentration y (% / m) in the event of a fire, and also shows the total brightness X (μW) of the smoke plume observed by the monitoring camera It shows.

  When a fire occurs in the surveillance area 16, as the scale of the fire expands, the smoke plume thickness 2r increases as shown in FIG. 11, and the smoke density y (% / m) generated there also increases, and the surveillance camera 10 The total brightness X (μW) of the smoke plume imaged by also increases.

In this case, the luminance ratio x (μW / pxl) indicating the luminance per pixel (per unit pixel) where the scattered light of the generated smoke is observed by the monitoring camera 10 is the horizontal direction occupied by the smoke plume in the observed image. Assuming that the number of pixels (hereinafter referred to as “the number of horizontal pixels”) is 2R pixels,
x = y / 2R (μW / pxl)
It becomes.

  FIG. 12 is a graph showing the relationship between the smoke plume thickness 2r (m) and the brightness rate x (μW / px1) together with the smoke concentration y (% / m), and the smoke plume thickness in FIG. It is based on the relationship between 2r and the total luminance value X (μW).

  The smoke plume thickness 2 r can be estimated by detecting the smoke plume brightness factor x from the observation image by the monitoring camera 10 from the relationship between the smoke plume thickness 2 r and the brightness factor x shown in FIG. 12. .

  The detection of the luminance ratio of the smoke plume in the observation screen captured by the surveillance camera 10 does not have to be calculated from the observation image, and the luminance of the pixels present in the area of the smoke plume may be detected.

(Relationship between brightness rate and distance)
FIG. 13 is a graph showing the relationship between the total brightness and the brightness ratio with respect to the distance to the flash point, and the brightness ratio x of the smoke plume present in the observation image of the monitoring camera 10 does not depend on the distance L to the flash point. It will always be a constant value. The reason is as follows.

  Now, let us consider the case where there is a smoke plume with a thickness 2r = 1 m from the surveillance camera 10 at a distance L1 = 30 m and the case from a distance L2 = 3 m. Here, let the plume which exists in distance L1 = 30 m be a 1st plume, and let the smoke plume which exists in distance L2 = 3 m be a 2nd plume.

The closer the smoke plume is to the surveillance camera 10, the higher the brightness of the smoke plume observed. If the total brightness measured from the smoke plume observed by the surveillance camera 10 is taken into consideration, the total brightness of each of the first plume and the second plume with different distances is X1 and X2, respectively.
X1 · L12 = X2 · L22
Relationship. That is, the total brightness X1, X2 of the smoke plume is inversely proportional to the square of the distances L1, L2 to the fire point.

For example, assuming that the distance of the first plume L1 = 30 (m) and the total brightness X1 is X1 = 10 (mW), the total brightness X2 of the second plume at which the distance L2 = 3 (m) is X2 = X1 · L12 / L22 = 1000 (mW)
It becomes.

Further, the luminance ratio x (μW / px1) per unit pixel of the surveillance camera 10 is obtained. Here, assuming that the number of horizontal pixels occupied by the smoke plume in the observation image is 2R pixels, the luminance ratio x is
x = X / (2R) 2
And
2R1 · L1 = 2R2 · L2
Because x1 = X1 / (2R1) 2
= X 1 / (2R 2 · L 2 / L 1) 2
= (X2 · L22 / L12) / (2R2 · L2 / L1) 2
= X 2 / (2 R 2) 2
= X 2
It becomes.

  That is, the luminance ratio x is constant regardless of the distance L, and depends only on the size 2r of the smoke plume. This is the same principle that the temperature measured in the radiation thermometer is independent of distance.

(The relationship between smoke plume thickness and distance)
If the thickness 2r can be estimated from the luminance ratio x of the smoke plume present in the observation image of the surveillance camera 10, the distance L from the surveillance camera 10 to the fire point generating the smoke plume is shown in FIG. It can be calculated from the relationship between the same viewing angle of the smoke plume and the fire point distance.

That is, assuming that the number of pixels in the horizontal direction on the observation screen corresponding to the thickness 2r of the smoke plume captured by the surveillance camera 10 is 2R pixels, the expected angle θ of the smoke plume is
θ = α · 2R (°) (Equation 3)
It becomes. This is the same as equation 1 described above.

Thus, when the prospect angle θ of the smoke plume is determined, the fire point distance L from the surveillance camera 10 to the smoke plume 26 is calculated based on the smoke plume thickness 2r obtained from the smoke plume luminance ratio x.
L = r / tan (θ / 2) (Equation 4)
It becomes. This is the same as Equation 2 described above.

(Judgment of fire)
In the fire judgment by the smoke plume occupying the scattered light image of the surveillance camera 10, the smoke plume thickness 2r estimated from the brightness ratio x of the smoke plume is not less than the predetermined threshold fire smoke plume threshold (2r) th When it becomes, it judges as a fire.

  In the present embodiment, the smoke plume of this model fire is determined in order to determine a model fire that generates a smoke plume with a smoke density y = 30 (% / m) at which the luminance ratio x = 1.84 (μw / pxl). Since the thickness 2r corresponding to the luminance ratio x = 1.84 (μw / px1) is 1.0 (m), the threshold thickness (2r) th = 1.0 (m) is set, and the threshold is set. If the thickness (2r) th or more, it is determined that a fire, if less than it is determined as a non-fire.

[2nd fire detection unit]
(Functional configuration of the second fire detection unit)
As shown in FIG. 2, the second fire detection unit 100 provided in the image processing apparatus 12 determines that the fire at the first stage is determined by the first fire detection unit 50 and turns off the floor illumination device 22 a and the wall illumination device 22 b. Then, the indoor lighting device 24 is turned on, and the monitoring area 16 is operated in the entire illumination state, and an image of the monitoring area which is 30 frames per second, for example, as moving image data captured by the monitoring camera 10 by transmission control of the transmission unit 28 The data is transmitted and stored in a memory (not shown) provided in the image processing apparatus 12.

  The second smoke image determination unit 130 determines a smoke image in which a smoke plume due to scattered light exists from the image captured by the monitoring camera 10. The second smoke image determining unit 130 determines the smoke image by, for example, detecting a smoke plume candidate area formed of a set of pixels having a predetermined threshold luminance or more that can be determined as a smoke plume, and detecting the smoke plume candidate area When the horizontal pixel number 2R of is greater than a predetermined threshold (2R) th, it is determined that the smoke image is highly likely to have a smoke plume due to a fire, and the horizontal pixel number 2R of the smoke plume candidate region in the determined smoke image is 2) The smoke image is sent to the prospect angle detection unit 132, and the determined luminance image is sent to the luminance ratio detection unit 134 to instruct the detection operation of the luminance ratio x.

  Moreover, as another embodiment of the second smoke image determination unit 130, a background image in which no smoke plume is present in the monitoring area is held in advance, and a difference image between the image captured by the monitoring camera 10 and the background image is generated A smoke plume area may be extracted, and a smoke image may be determined when the horizontal pixel number 2R of the smoke plume area is equal to or greater than a predetermined threshold (2R) th. The background image is appropriately updated in the absence of the smoke plume.

  The threshold (2R) th of the horizontal pixel number determined to be a smoke image by the second smoke image determination unit 130 generates, for example, a smoke plume of thickness 2r = 1.0 (m) at the maximum distance L = 30 (m) Assuming a fire model, since the horizontal pixel number 2R of the smoke plume in the observation image is 2R = 12 pixels in this case, the threshold (2R) th is set to (2R) th = 12 pixels.

  The second expected angle detection unit 132 calculates the expected angle θ of the smoke plume according to the equation 3 from the horizontal pixel number 2R of the smoke plume candidate region in the smoke image determined by the second smoke image determination unit 130, and the second distance It is output to the calculation unit 138.

  On the other hand, the luminance ratio detection unit 134 detects the luminance of the pixel of the smoke plume candidate region in the smoke image determined by the second smoke image determination unit 130 as the luminance ratio x. The luminance factor x in this case may be detected as an average value of a plurality of pixels entering the smoke plume.

  The second plume thickness estimation unit 136 estimates the smoke plume thickness 2 r from the luminance ratio x detected by the luminance ratio detection unit 134 based on the relationship between the luminance ratio x and the plume thickness 2 r shown in FIG. 12. . For example, the second plume thickness estimation unit 136 sets a plurality of linear expressions or quadratic expressions that approximate the graph characteristics of the luminance ratio x and the plume thickness 2r shown in FIG. By substituting the luminance factor x, the thickness 2r of the smoke plume is calculated and estimated.

  Also, the second plume thickness estimation unit 136 prepares a binary table based on the graph characteristics of the luminance ratio x and the plume thickness 2r shown in FIG. The plume thickness 2r may be read out.

  The second distance calculation unit 138 is based on the equation 4 from the smoke plume perspective angle θ detected by the second prospect angle detection unit 132 and the smoke plume thickness 2 r estimated by the second plume thickness estimation unit 136. The fire point distance L from the surveillance camera 10 to the smoke plume is calculated.

  The second fire determination unit 140 determines that the second stage fire is established (fire determination) when the smoke plume thickness 2r estimated by the second plume thickness estimation unit 136 is equal to or greater than a predetermined threshold (2r) th. Otherwise, it is determined that there is no fire, and if it is determined that the fire is the second stage, the smoke plume thickness 2r estimated by the second plume thickness estimation unit 136 and / or the second distance calculation unit 138 The second fire signal is output to the external fire alarm system 14 together with the calculated data of the fire point distance L, and a fire alarm is outputted, and for example, the thickness 2r of the smoke plume and / or the fire point distance L are displayed.

(Specific example of fire point detection based on scattered light image)
Now, assuming that the horizontal pixel number 2R of the smoke plume candidate area determined by the second smoke image determination unit 130 is 2R = 46 pixels, the estimated angle θ calculated by the second estimated angle detection unit 132 is θ according to Equation 3 above. = 0.064 x 46 = 2.94 °
It becomes.

  At this time, assuming that the brightness ratio x of the smoke plume detected from the smoke image by the brightness ratio detection unit 134 is x = 18.4 (μW / pxl), the smoke is obtained from the relationship between the brightness ratio x and the plume thickness 2r in FIG. The plume thickness 2r is estimated to be 2r = 1.0 (m).

Further, since the second distance calculation unit 138 has tan (θ / 2) = 23/700, the fire point distance L from the monitoring camera 10 to the fire point is expressed by
L = 15.2 (m)
Calculate

  The second fire determination unit 140 determines a predetermined threshold (2r) th for determining a fire from the smoke plume thickness 2r estimated by the second plume thickness estimation unit 136, for example, (2r) th = 1.0 (m) Assuming that the smoke plume thickness 2r = 1.0 (m) estimated at this time matches the threshold (2r) th = 1.0 (m), it is determined that a fire occurs.

  Therefore, the second fire determination unit 140 outputs the second fire signal to the fire alarm system 14 together with the smoke plume thickness data and the fire point distance data, and outputs the fire alarm and the smoke plume thickness d = 1. The fire point distance L = 15.2 (m) is displayed with 0 (m) to make it possible to check the status of the fire that has occurred in the monitoring area.

  On the other hand, even if the horizontal pixel number 2R of the smoke plume in the smoke image is 2R = 46 pixels and the prospect angle θ is the same θ = 2.94 °, the luminance ratio x of the smoke plume is, for example, x = 5.0 ( Assuming that it is μW / pxl), the thickness of the smoke plume in this case is estimated to be 2r = 0.5 (m) from the relationship of FIG. 5, and the fire point distance L from the surveillance camera 10 to the fire point is From 4 to L = 7.6 (m).

  In this case, the thickness 2r = 0.5 (m) of the smoke plume is less than the threshold (2r) th = 1.0 (m) for determining the fire, and it is determined that the fire is not a fire.

(Detection of black smoke fire by light reduction image)
The smoke plume of white smoke generated when wood, cloth, paper or the like is roasted maintains the substantially same relationship between plume thickness and smoke density as shown in FIG. 11, although there are some differences. For this reason, regardless of the target to be roasted, the relationship between the brightness ratio and the thickness of the smoke plume shown in FIG. 11 is maintained, and the fire detection by the second fire detection unit 100 of FIG. 2 becomes possible.

  However, when oil or gas burns with a flame, black smoke is generated instead of white smoke generated by torrefaction, and the relationship between fire size, that is, plume thickness and light scattered by smoke, is the case of torrefaction fire It is different from.

  In this case, it is necessary to first confirm the presence of a flame and to recognize that black smoke is generated as a result of the fire. The relationship between plume thickness and scattered light must be replaced with a model smoke of black smoke.

  Therefore, when a fire is detected from the smoke image of the black smoke plume, the second plume thickness estimation unit 136 provided in the second fire detection unit 100 of FIG. By setting the relationship of (1), it is possible to estimate the thickness of the black smoke plume and determine the fire, as in the case based on the relationship of FIG. 12 when white smoke is generated.

[Fire detection processing]
(Outline of fire detection processing)
FIG. 14 is a flowchart showing an outline of the fire detection process according to the embodiment of FIG. As shown in FIG. 14, first, in step S1 (hereinafter "step" is omitted), the floor lighting device 22a and the wall lighting device 22b are turned on by the illumination switching unit 42, and as shown in FIG. The wall surface 16a and the floor surface 16b which become the background of the monitoring area | region 16 to image pick-up are background-illuminated with fixed illumination intensity.

  Then, it progresses to S2 and the 1st fire detection part 50 performs a 1st fire detection process. That is, the first fire detection unit 50 executes a process of estimating the thickness of the smoke plume and the fire point distance from the dimmed image of smoke captured by the monitoring camera 10 to determine the fire at the first stage, and in S3 When the determination result of the fire at the stage is determined, the first fire signal is output to the fire notification facility 14 together with the data indicating the thickness of the smoke plume and the fire point distance at S4 and the fire notification facility 14 as a first stage fire alarm, for example Output a fire alarm (pre-alarm) and display the smoke plume thickness and the distance to the fire point.

  Subsequently, the process proceeds to S5, the illumination switching unit 42 turns off the floor illumination device 22a and the wall illumination device 22b to stop the background illumination, and turns on the indoor illumination device 24 to switch to the general illumination of the monitoring area 16.

  Subsequently, the process proceeds to S6, and the second fire detection process is executed by the second fire detection unit 100 in a state where the monitoring area 16 is switched to the entire illumination. That is, the second fire detection unit 100 executes processing of estimating the thickness of the smoke plume and the fire point distance from the scattered light image of smoke captured by the monitoring camera 10 to determine the second stage fire, and the fire of S2 is performed. When the judgment result is determined, the second fire signal is output to the fire alarm system 14 together with the data indicating the smoke plume thickness and the fire point distance in S8, and the fire alarm equipment 14 outputs a fire alarm and the smoke plume thickness and fire Display the point distance.

(Details of the first fire detection process)
FIG. 15 is a flowchart showing the details of the first fire detection process in S2 of FIG. 14, which is the control operation of the first fire detection unit 50 of FIG. 2.

  In FIG. 15, first, a fire pixel is determined from the threshold (2R) th of the horizontal pixel number for determining the smoke plume area in the smoke image in S11, the expected angle α per pixel in the monitoring camera 10, and the thickness of the smoke plume. The threshold (2R) th is set as a constant.

  Subsequently, in S12, the smoke plume area is detected from the difference image between the observation image captured by the monitoring camera 10 and the background image stored in advance, and the horizontal pixel number 2R of the predetermined height H of the smoke plume area is determined. If it is more than a predetermined threshold (2R) th, it is determined as a smoke image, and the process proceeds to S14.

  In S14, an expected angle θ is calculated from the horizontal pixel number 2R of the smoke plume detected in S12, and then the process proceeds to S15 to detect the dimming ratio Y of the smoke plume in the smoke image. Subsequently, in S16, the smoke plume thickness 2r is estimated from the light reduction ratio Y of the smoke plume, and then in S17, the fire point distance L is calculated from the smoke plume prospect angle θ and the thickness 2r.

  Subsequently, the process proceeds to S18, and if the smoke plume thickness 2r is equal to or more than the fire threshold (2r) th, it is determined that the fire is the first stage, and the process returns to S3 of FIG. 15 to determine the determination result of the first stage fire. Then, the process proceeds to S4, and the first fire signal is output together with the data of the smoke plume thickness 2r and / or the fire point distance L.

(Details of the second fire detection process)
FIG. 16 is a flowchart showing the details of the second fire detection process in S6 of FIG. 14, which is the control operation of the second fire detection unit 100 of FIG. 2.

  In FIG. 16, first, in step S21, a fire is determined from the threshold (2R) th of the horizontal pixel number to determine the smoke plume candidate region in the smoke image, the viewing angle α per pixel in the monitoring camera 10, and the thickness of the smoke plume The fire determination threshold (2R) th is set as a constant.

  Subsequently, the process proceeds to S22, a smoke plume candidate area formed of a pixel set having a predetermined luminance or more is detected from the observation image captured by the monitoring camera 10, and the horizontal pixel number 2R of the smoke plume candidate area is determined. If the threshold value (2R) th or more, the smoke image is determined, and the process proceeds to S24.

  In S24, an expected angle θ is calculated from the horizontal pixel number 2R of the smoke plume detected in S22, and then, in S25, the luminance of the smoke plume in the smoke image is detected as the luminance factor x.

  Subsequently, in S26, the smoke plume thickness 2r is estimated from the brightness ratio x of the smoke plume, and then in S27, the fire point distance L is calculated from the smoke plume prospect angle θ and the thickness 2r.

  Subsequently, the process proceeds to S28, and if the smoke plume thickness 2r is equal to or more than the fire threshold (2r) th, it is determined that the fire is the second stage, and the process returns to S7 of FIG. The second fire signal is output together with data of smoke plume thickness 2r and / or fire point distance L.

[Application of fire point distance and smoke plume thickness]
(Application based on estimation of fire point distance)
The smoke 20 in the monitoring area 16 of FIG. 1 is generated by using the fire point distance L output when the image processing apparatus 12 of FIG. 2 determines the first stage fire or the second stage fire. You can identify the location of the fire point.

  Once the fire point position of the smoke 20 in the monitoring area 16 can be identified, for example, by transmitting the position information of the smoke to the fire extinguisher, an appropriate fire extinguishing becomes possible. For example, if a sprinkler fire extinguisher equipped with a remotely controllable sprinkler head is installed, only the sprinkler head close to the fire point position is operated. In addition, the movable fire extinguishing robot is automatically moved to the vicinity of the heat point. In addition, position control of the water discharge gun is performed.

  In addition, in a large space facility that is automated, such as a factory or an automatic warehouse, it becomes possible to take appropriate measures such as stopping the operation of the target facility and operating the attached fire extinguishing device by knowing the fire point position.

  In addition, even in the case of an initial fire fighting activity by a person, it is possible to go straight to the position of the fire point, which enables a quick response. In addition, at the time of evacuation guidance, it is possible to set an accurate route. Furthermore, it is possible to provide information on the exact location of the fire point to fire brigade personnel, and lead to life saving and damage control by achieving improvement of the fire extinguishing efficiency. Besides this, various measures can be made by knowing the fire point distance.

(Application based on smoke plume thickness estimation)
By using the smoke plume thickness that is output when the image processing apparatus 12 of FIG. 2 determines the first stage fire and the second stage fire, that is, using the estimated value of the size (scale) of the fire point The following applications are possible.

  For example, it becomes possible to use an appropriate fire extinguishing agent according to the size (scale) of smoke, and it becomes possible to extinguish the fire reliably with a small amount of fire extinguishing agent, leading to pollution prevention and property protection.

  In addition, it can be understood from the rapid expansion change of the smoke plume that the rapid expansion of the fire can be recognized, and evacuation guidance can be started early and appropriately, leading to life saving. Besides this, various measures can be taken by knowing the scale of the fire from the thickness of the smoke plume.

[Modification of the present invention]
(Fire judgment)
In the above embodiment, the first fire detection unit determines the first fire from the dimmed image of the smoke plume and outputs the first fire signal, and then the second fire detection unit determines the scattered light image of the smoke plume. The second fire signal is judged by judging the second fire from the second fire, but the second fire which is judged the fire decision without outputting the fire signal when the first fire is judged If determined, a fire determination signal may be output to notify a fire alarm.

(Smoke plume thickness and fire point distance)
In the above embodiment, in addition to the first fire signal or the second fire signal, when the fire of the first stage is determined from the dimmed image of smoke or when the fire of the second stage is determined from the scattered light image of smoke. Although data of estimated smoke plume thickness and / or fire point distance is output, only the first fire signal or the second fire signal may be output.

(Non-fire judgment)
The above embodiment determines that the fire of the first stage or the fire of the second stage is determined if the thickness of the smoke plume estimated from the light reduced image of smoke or the scattered light image of smoke is equal to or greater than a predetermined threshold. Although the data indicating the fire point distance to the smoke plume and / or the smoke plume thickness is output together with the fire signal or the second fire signal, the smoke plume together with the non-fire smoke detection signal is also output when it is determined that the fire is not fire. Output data indicating the distance to the flash point and / or the thickness of the smoke plume, for example, by outputting a warning alert by non-fire smoke detection, and displaying the distance between the fire point and the thickness of the smoke plume Informing the use of the fire in the monitoring area which is

(Surveillance camera)
In the above embodiment, although the case where the horizontal one-side viewing angle θ of the monitoring camera is 45 ° is taken as an example for simplicity of explanation, the present invention can be applied to an appropriate viewing angle. Further, the number of horizontal and vertical pixels of the surveillance camera is not limited to (1400 × 1000) pixels, and one having an appropriate resolution can be used.

(Image processing device)
In the above embodiment, the monitoring camera and the image processing apparatus are separately disposed and connected by the transmission path, but may be an apparatus in which both are integrated.

(Others)
Further, the present invention is not limited to the above-described embodiment, includes appropriate modifications that do not impair the objects and advantages thereof, and is not limited by the numerical values shown in the above-described embodiment.

[Features of the Invention]
Here, the features of the present invention will be summarized as follows.

(Feature 1) (System)
Imaging means for imaging a monitoring area to be a partition space;
Background illumination means for illuminating a wall surface and a floor surface as background of the monitoring area imaged by the imaging means with a constant illuminance;
General illumination means for overall illumination of the monitoring area imaged by the imaging means;
A first fire detection means for detecting a first-stage fire from a dimmed image of a smoke plume generated in the monitoring area captured by the imaging means and outputting a first fire signal while the monitoring area is illuminated in the background When,
Illumination switching means for stopping background illumination by the background illumination means and switching to overall illumination by the overall illumination means when the first fire detection means detects a first stage fire;
The second fire signal is detected by detecting a second stage fire from the scattered light image of the smoke plume generated in the monitoring area captured by the imaging unit in a state where the monitoring area is switched to the entire illumination by the light switching unit. Second fire detection means to output;
And a fire detection system (claim 1).

(Feature 2) (First fire detection means)
In the fire detection and system described in Feature 1,
The first fire detection means is
First smoke image determining means for determining a smoke image in which a smoke plume is present from an image by background illumination of the monitoring area captured by the imaging means;
A light reduction rate detection means for detecting a light reduction rate by a smoke plume from the smoke image determined by the first smoke image determination means;
First plume thickness estimating means for estimating the thickness of the smoke plume from the light reduction rate detected by the light reduction rate detecting means;
First fire determination means for determining a first stage fire and outputting a first fire signal when the thickness of the smoke plume estimated by the first plume thickness estimation means is equal to or greater than a predetermined threshold value;
Fire detection system characterized by

  According to this feature 2, the smoke plume generated by the fire is illuminated by illuminating the floor surface and wall surface serving as the background of the monitoring area imaged by the imaging means at a constant illuminance without illuminating the space where the smoke in the monitoring area rises. Detecting the light attenuation rate due to the smoke from the observation image, estimate the thickness of the smoke plume from the light attenuation rate of the smoke plume which becomes constant regardless of the preset distance, the thickness of the smoke plume is a predetermined fire judgment threshold In the above case, by determining as the first stage fire, the first stage fire is surely detected from the observation image which is reduced by the smoke plume whose size changes depending on the distance, for example, a fire alarm (pre alarm) Can be notified.

(Feature 3) (Second fire detection means)
In the fire detection and system described in Feature 1,
The second fire detection means is
Second smoke image determining means for determining a smoke image in which a smoke plume is present from an image of the entire monitoring area imaged by the imaging means from the overall illumination;
Luminance factor detection means for detecting the luminance rate per unit pixel of the smoke plume from the smoke image judged by the second smoke image judgment means;
Second plume thickness estimating means for estimating the thickness of the smoke plume from the luminance rate detected by the luminance rate detecting means;
Second fire determination means for determining a second stage fire and outputting a second fire signal when the smoke plume thickness estimated by the second plume thickness estimation means is equal to or greater than a predetermined threshold value;
Fire detection system characterized by

According to this feature 3, the thickness of the smoke plume can be estimated from the brightness rate of the smoke plume which becomes constant regardless of the distance, and the thickness of the smoke plume determined by a predetermined model fire is used as the fire judgment threshold. In the above case, the fire detection is performed by determining the fire at the second stage from the scattered light image of the smoke plume following the fire precursor warning by the detection of the first stage fire based on the dimmed image by determining as the fire. It makes it possible to detect and warn fire from the observation image of smoke plume which is fixed and changes in size depending on the distance.
Also, even if the first stage fire is erroneously detected from the dimmed image of the smoke plume because the light from the background illumination is temporarily blocked by an object other than smoke, for example, a person, the first stage fire detection Based on the scattered light image captured by switching to the overall illumination of the surveillance area based on the brightness ratio is different from smoke, the thickness of the smoke plume does not exceed the threshold for determining fire, and false notification due to non-fire cause Can be prevented.

(Feature 4) (First distance estimation)
The fire detection system according to Feature 2, further, wherein the first fire detection means is
First expected angle detection means for detecting an expected angle of a smoke plume from the smoke image determined by the first smoke image determination means;
The fire point distance from the imaging means to the smoke plume is calculated based on the smoke plume's expected angle detected by the first prospect angle detection means and the thickness of the smoke plume estimated by the first plume thickness estimation means First distance calculating means;
And the first fire determining means determines the fire point distance calculated by the first distance calculating means and / or the smoke plume thickness estimated by the first plume thickness estimating means when determining the first stage fire. A fire detection system characterized by outputting information indicating the height together with the first fire signal.

  According to this feature 4, the fire point distance from the imaging means to the flame can be determined based on the thickness of the smoke plume estimated from the light reduction rate of the smoke plume, and the fire of the first stage from the thickness of the smoke plume By determining the fire point distance and / or the thickness of the smoke plume together with the first fire signal, for example, a fire prediction alarm (pre-alarm) is output and the flame distance and the smoke plume thickness (size) Is displayed, thereby facilitating grasping of the first stage fire occurrence situation in the monitoring area and enabling appropriate measures.

(Feature 5) (Second distance estimation)
The fire detection system according to Feature 3, further, the second fire detection means
Second expected angle detection means for detecting an expected angle of a smoke plume from the smoke image determined by the second smoke image determination means;
The second embodiment calculates a fire point distance from the image pickup means to the smoke plume based on the smoke plume's expected angle detected by the second expected angle detection means and the smoke plume thickness estimated by the plume thickness estimation means. Distance calculation means,
Provide
The second fire determination means indicates the fire point distance calculated by the second distance calculation means and / or the smoke plume thickness estimated by the second plume thickness estimation means when the fire of the second stage is determined. A fire detection system characterized by outputting information together with the second fire signal.

  According to the feature 5, the fire point distance can be obtained based on the thickness of the smoke plume estimated from the luminance ratio of the smoke plume, and when the fire is judged from the thickness of the smoke plume, the fire is generated together with the second fire signal. By outputting the point distance and / or the thickness of the smoke plume, for example, the fire alarm is outputted and the flame distance and the size (size) of the smoke plume are displayed, thereby grasping the occurrence of the fire in the monitoring area Make it easy and take appropriate action.

(Feature 6) (Determination of smoke image by background lighting)
In the fire detection system according to Feature 3, the first smoke image determination means holds a background image in which no smoke plume exists in the monitoring area, and a difference image between the image captured by the imaging means and the background image A fire detection system characterized by generating a smoke plume area and determining a smoke image if the number of horizontal pixels in the smoke plume area is equal to or greater than a predetermined threshold.

(Feature 7) (Detection of attenuation rate)
In the fire detection system according to Feature 6, the light reduction rate detection means includes the luminance of a horizontal pixel row of a predetermined height of the smoke plume area extracted from the difference image generated by the first smoke image determination means; What is claimed is: 1. A fire detection system comprising: calculating a light reduction rate of a smoke plume based on the brightness of the horizontal pixel row of the background image at the same position as the horizontal pixel row.

(Feature 8) (Thickness estimation of smoke plume)
In the fire detection system according to Feature 3, the first plume thickness estimating means sets in advance the relationship between the light attenuation rate by smoke plume and the thickness obtained from a predetermined model fire, and the thickness based on the relationship. A fire detection system characterized in that the thickness of a smoke plume is estimated from the reduction rate of the smoke plume detected by the light reduction rate detection means.

(Characteristic 9) (Calculation of the fire point distance)
In the fire detection system according to Feature 4, when the thickness of the smoke plume estimated is 2r and the estimated angle of the smoke plume is θ, the first distance calculation means sets the fire point distance L as follows:
L = r / tan (θ / 2)
Fire detection system characterized by calculating and estimating.

(Feature 10) (Determination of smoke image by total illumination)
In the fire detection system according to Feature 3, the second image judging means detects a smoke plume candidate area which is a set of pixels having a predetermined luminance or more from the image picked up by the image pickup means and detects the smoke plume candidate area. A fire detection system characterized by determining as a smoke image when the number of pixels in the horizontal direction is equal to or more than a predetermined threshold.

(Feature 11) (Estimation of plume thickness by luminance rate)
In the fire detection system according to Feature 3, the two plume thickness estimation means sets the relationship between the luminance ratio and the thickness of the smoke plume based on a predetermined empirical formula, and detects the luminance ratio based on the relationship. A fire detection system characterized in that the thickness of a smoke plume is estimated from the luminance rate detected by means.

(Feature 12) (Calculation of the distance to the fire point)
In the fire detection system according to Feature 5, the second distance calculation means sets the fire point distance L, where the estimated smoke plume thickness is 2r and the smoke plume prospective angle is θ.
L = r / tan (θ / 2)
Fire detection system characterized by calculating and estimating.

(Feature 13) (Method)
The first stage fire is detected from the dimmed image of the smoke plume generated in the monitoring area captured by the imaging unit in a state in which the wall surface and the floor surface serving as the background of the monitoring area forming the partition space are illuminated at constant illuminance. And a first fire detection step of outputting a first fire signal,
When a first stage fire is detected in the first fire detection step, the second monitoring area is switched to the entire illumination, and the second image is a scattered light image of smoke plume generated in the monitoring area captured by the imaging unit. A second fire detection step of detecting a stage fire and outputting a second fire signal;
And a fire detection method (claim 2).

(Feature 14) (First fire detection means)
In the fire alarm method according to the feature 13, the first fire detection step includes:
A first smoke image determining step of determining a smoke image including a smoke plume from an image of background light of the monitoring area captured by the imaging unit;
A light reduction rate detection step of detecting a light reduction rate by a smoke plume from the smoke image determined by the first smoke image determination step;
A first plume thickness estimation step of estimating the thickness of the smoke plume from the light reduction rate detected in the light reduction rate detection step;
A first fire determination step of determining a first stage fire and outputting a first fire signal when the smoke plume thickness estimated in the first plume thickness estimation step is equal to or greater than a predetermined threshold value;
A fire detection method characterized in that

(Feature 15) (Second fire detection means)
The fire detection method according to feature 13, wherein the second fire detection step includes:
A second smoke image determining step of determining a smoke image in which a smoke plume is present from an image by total illumination of the monitoring area captured by the imaging means;
A luminance ratio detection step of detecting a luminance ratio per unit pixel of the smoke plume from the smoke image determined in the second smoke image determination step;
A second plume thickness estimation step of estimating the thickness of the smoke plume from the luminance rate detected in the luminance rate detection step;
A second fire determination step of determining a second stage fire and outputting a second fire signal when the thickness of the smoke plume estimated in the second plume thickness estimation step is equal to or greater than a predetermined threshold value;
A fire detection method characterized in that

(Feature 16) (First distance estimation)
The fire detection method according to feature 14, further, wherein the first fire detection step includes:
A first prospective angle detection step of detecting a prospective angle of a smoke plume from the smoke image determined by the first smoke image determination step;
The fire point distance from the imaging means to the smoke plume is calculated based on the smoke plume's expected angle detected in the first prospect angle detection step and the smoke plume thickness estimated in the first plume thickness estimation step. A first distance calculating step;
And the first fire determination step determines the fire point distance calculated in the first distance calculation step and / or the smoke plume thickness estimated in the first plume thickness estimation step when the fire of the first step is determined. A fire detection method comprising: outputting information indicative of the noise together with the first fire signal.

(Feature 17) (Second distance estimation)
The fire detection method according to feature 15, further comprising: the second fire detection step
A second prospective angle detection step of detecting a prospective angle of a smoke plume from the smoke image determined by the second smoke image determination step;
The second embodiment calculates a fire point distance from the imaging means to the smoke plume based on the smoke plume's expected angle detected in the second prospect angle detection step and the smoke plume thickness estimated in the plume thickness estimation step. Distance calculation step,
And the second fire determination step determines the fire point distance calculated in the second distance calculation step and / or the smoke plume thickness estimated in the second plume thickness estimation step when the fire of the second step is determined. A fire detection method comprising: outputting information indicative of the noise together with the second fire signal.

(Feature 18) (Determination of smoke image by background lighting)
In the fire detection method according to the feature 15, the first smoke image determination step holds a background image in which no smoke plume exists in the monitoring area, and a difference image between the image captured by the imaging unit and the background image And detecting a smoke plume area, and determining a smoke image when the horizontal pixel number of the smoke plume area is equal to or more than a predetermined threshold.

(Feature 19) (Detection of attenuation rate)
In the fire detection method according to the feature 18, the light reduction rate detection step includes the luminance of a horizontal pixel row of a predetermined height of the smoke plume area extracted from the difference image generated in the first smoke image determination step; What is claimed is: 1. A fire detection method comprising: calculating a light reduction rate of a smoke plume based on the brightness of the horizontal pixel row of the background image at the same position as the horizontal pixel row.

(Feature 20) (Thickness estimation of smoke plume)
In the fire detection method according to the feature 15, in the first plume thickness estimation step, the relationship between the light reduction rate by smoke plume and the thickness determined from a predetermined model fire is set in advance, and the first plume thickness estimation step is based on the relationship. What is claimed is: 1. A fire detection method comprising: estimating a smoke plume thickness from a smoke plume attenuation rate detected in a dimming rate detection step.

(Feature 21) (Calculation of the distance to the fire point)
In the fire detection method according to the feature 16, when the thickness of the smoke plume estimated is 2r and the estimated angle of the smoke plume is θ, the first distance calculation step sets the fire point distance L to
L = r / tan (θ / 2)
A fire detection method characterized by calculating and estimating according to.

(Feature 22) (Determination of smoke image by total illumination)
In the fire detection method according to the feature 15, the second image determination step detects a smoke plume candidate area which is a set of pixels having a predetermined luminance or more from the image picked up by the image pickup means, and detects the smoke plume candidate area. A fire detection method characterized in that a smoke image is determined when the number of pixels in the horizontal direction is equal to or more than a predetermined threshold.

(Feature 23) (Estimate of plume thickness by luminance rate)
In the fire detection method according to the feature 16, the two plume thickness estimation step sets the relationship between the brightness ratio of the smoke plume and the thickness based on a predetermined experimental formula, and the brightness ratio detection based on the relationship. A fire detection method characterized in that the thickness of a smoke plume is estimated from the luminance rate detected by means.

(Feature 24) (Calculation of the distance to the fire point)
In the fire alarm method according to the feature 17, the second distance calculating step sets the fire point distance L to the estimated smoke plume thickness 2r and the smoke plume probable angle θ.
L = r / tan (θ / 2)
A fire detection method characterized by calculating and estimating according to.

10: Surveillance camera 12: Image processing device 14: Fire alarm equipment 15: Shooting area 16: Surveillance area 18: Fire point 20: Smoke 22a: Floor illumination device 22b: Wall illumination device 24: Interior illumination device 26: Smoke plume 28 : Transmission unit 30: First smoke image determination unit 32: First prospect detection output unit 34: Light reduction rate detection unit 36: First plume thickness estimation unit 38: First distance calculation unit 40: First fire determination unit 42 : Illumination switching unit 44: Background image 45: Observation image 46: Difference image 47: Smoke plume area 48: Horizontal pixel row 50: First fire detection unit 100: Second fire detection unit 130: Second smoke image determination unit 132: Second expected angle detection unit 134: luminance ratio detection unit 136: second plume thickness estimation unit 138: second distance calculation unit 140: second fire determination unit

Claims (2)

Imaging means for imaging a monitoring area to be a partition space;
Background illumination means for background illumination of the background of the monitoring area imaged by the imaging means at a constant illuminance;
General illumination means for overall illumination of the monitoring area imaged by the imaging means;
A first fire detection means for detecting a first-stage fire from a dimmed image of a smoke plume generated in the monitoring area captured by the imaging means and outputting a first fire signal while the monitoring area is illuminated in the background When,
Illumination switching means for stopping background illumination by the background illumination means and switching to overall illumination by the overall illumination means when the first fire detection means detects a fire at the first stage;
A second fire signal is detected by detecting a second-stage fire from the scattered light image of the smoke plume generated in the monitoring area captured by the imaging unit while the monitoring area is switched to the entire illumination by the light switching unit. Second fire detection means for outputting
Fire detection system characterized by
The first fire signal is detected by detecting a fire at the first stage from a dimmed image of the smoke plume generated in the monitoring area captured by the imaging unit in a state where the background of the monitoring area forming the partition space is background illuminated with constant illumination. The first fire detection step to output
When the fire at the first stage is detected by the first fire detection step, the background illumination is stopped and the monitoring area is switched to the general illumination, and occurs in the monitoring area imaged by the imaging unit A second fire detection step of detecting a second fire from the scattered light image of the smoke plume and outputting a second fire signal;
A fire detection method characterized in that

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