JP2549435B2 - Fire judgment device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fire judging device adapted to judge a fire from a rising speed of smoke or flame due to a hot air flow at the time of a fire.

[Prior Art] A conventional fire determination device uses a sensor to detect a physical change in temperature, smoke concentration, gas concentration, etc. associated with the fire to determine the fire. In terms of compatibility, the situation is not always perfect.

On the other hand, in recent years, it has been known as a solid-state image sensor.
The use of CCD has become widespread, and it has been attempted to judge a fire from a surveillance image captured by a CCD camera in the field of fire surveillance.

For example, it has been considered to detect a flame due to a fire having a high brightness in the surroundings from an image of a CCD camera to give an alarm.

[Problems to be Solved by the Invention] However, in such a fire determination device that uses image information from a conventional CCD camera or the like, it is possible to determine a fire based on image information that includes a temporally and spatially varying component. The concept of extracting only necessary elements has not been fully established, and it is difficult to distinguish it from a lighter other than a fire or a fire of a cigarette at a conventional brightness change, and there is a problem in reliability.

The present invention has been made in view of such conventional problems, and as one method for determining a fire by extracting components associated with a fire from image information, the smoke and flame rise speed during the fire It is an object of the present invention to provide a fire determination device that determines a fire by generating information corresponding to the rising speed of smoke or flame from image information.

[Means for Solving the Problems] In order to achieve this object, in the present invention, means for imaging the fire monitoring area; and smoke that rises and moves within the imaging area based on the image information obtained from the imaging means. Frequency information generating means for generating frequency information according to the moving speed of the fire or flame; and fire judging means for judging a fire by comparing the frequency obtained by the frequency information generating means with a predetermined threshold frequency; It is the one.

[Operation] According to the fire determining apparatus of the present invention having such a configuration, the smoke rising speed during a fire is usually 0.5 m / s or more, and the flame rising speed is about 4 to 6 m / s. Therefore, the smoke rise is the grayscale distribution rise, and the flame rise is the fireball rise, which is extracted from the imaging information and converted into frequency components corresponding to each rise speed, for example, 0.5 m / s When a frequency component equal to or higher than the threshold frequency is detected, it is determined as a fire.

[Embodiment] FIG. 1 is a configuration diagram of an embodiment showing one embodiment of the present invention.

In FIG. 1, reference numeral 10 denotes a lens, and a subject image of a caution area by the lens 10 is formed on a light receiving surface of a CCD (solid-state image pickup device) 12 provided as an image pickup means and converted into an electric signal. The CCD 12 is driven by the CCD drive circuit 14, for example NTSC
According to the method, the video information is read out in units of each of the odd field (Odd) and even field (Even), and AD
Convert to digital signal with converter 16 and frame memory
Write to 18. The refreshing of the video information for the frame memory 18 may be performed in the same cycle as a normal television system, but since the information in the frame memory 18 does not need to be displayed on a CRT or the like, the calculation to be made clear in the later description The memory refresh may be repeated at a cycle according to the processing speed of the processing.

Next to the frame memory 18, an arithmetic control unit 2 using a CPU
0 is provided, the read / write control of the CCD drive circuit 14 and the frame memory 18 is performed by the arithmetic control unit 20, and the image component due to the rising movement of smoke or flame included in the image information stored in the frame memory 18 at the time of fire. Is extracted to generate a frequency component.

The frequency information corresponding to the rising speed of smoke or flame at the time of fire generated by the arithmetic control unit 20 is given to the fire determination unit 22, and the fire determination is performed by comparing with the threshold frequency preset in the fire determination unit 22. The fire judgment output is output to a fire alarm unit (not shown).

Next, the principle of generating frequency information corresponding to the rising speed from the image information of rising smoke or flame at the time of fire performed in the arithmetic and control unit 20 of FIG. 1 will be described.

FIG. 2 shows one of the image information stored in the frame memory 18 of FIG. 1, and naturally corresponds to the light receiving surface of the CCD 12 one to one.

The image information in Fig. 2 is a moving object indicated by a circle that becomes smoke or flame.
With respect to the ascending direction of 24, the screen is
= 10 divisions, and positive and negative polarities are alternately assigned to each of the 10 divisions, for example,-++ -...- + from the lower side.

For one image stored in the frame memory 18, for example, image reading is started from the lower left corner in the x direction, and when one line has been read, read scanning is performed to return to the upper left one.

In order to simplify the explanation here, if the moving object 24 at the bottom position moves N divided areas one by one each time the frame memory 18 is refreshed, the moving object 24 moves from the frame memory 18 once. In reading the frame, the video signal which is alternately repeated with-++-which has a time lag for each frame according to the movement of the moving object 24 shown in FIG. 3 (a).
You get 26. By converting such a video signal 26 into a rectangular wave signal 28 that has an L level when it falls to the minus side and an H level when it rises to the plus side, the rising speed of the moving object 24 shown in FIG. It is possible to obtain a signal having a corresponding frequency.

The generation of the frequency signal representing the moving speed shown in FIG. 3 (a) can be realized by a hard logic as shown in FIG. 4, for example.

In FIG. 4, reference numeral 30 is a comparator, which compares the video data read from the frame memory 18 with a reference value from a reference power source 32 for discriminating smoke or flame, and extracts only smoke or flame components. Of course, the comparator 30 is a digital comparator, and in order to accurately extract the flame and smoke components, not only the comparison and determination with the simple reference value but also the two-dimensional information stored in the frame memory 18
It is necessary to perform spatiotemporal filtering that extracts only moving components.

The smoke or flame video data detected by the comparator 30 is input to the AND gates 34 and 36, respectively. An odd field signal Odd is input to the AND gate 34, and an even field signal Even is input to the AND gate 36. That is, in the odd field, the AND gate 34 is set to the permissible state, the video data from the comparator 30 resets the FF 38 in the next stage, and Q = L level output. Further, in the even field, the AND gate 36 is in the allowable state, and if video data is obtained from the comparator 30 in this state, the FF 38 in the reset state is set and Q = H. That is, as shown in FIG. 2, the FF38 is reset by the video data corresponding to the negative polarity set in the odd field, and the FF38 is set by the video data corresponding to the positive polarity set in the even field. It is possible to generate the signal 28 indicating the frequency at which the video data alternately output with the positive and negative polarities shown in a) repeats.

FIG. 3 (b) shows a case where the rising speed of smoke or flame is low as compared with FIG. 3 (a). In this case, the moving object is in the same area position during two frames, and After refreshing, the frequency is moved to the next area position, and the frequency is half that of FIG.

Next, referring to FIG. 5, the lens in the embodiment of FIG.
The relationship between the magnification of 10, the distance to the flame or smoke moving upward, the rising speed, and the detection frequency will be described.

FIG. 5 shows a state in which an image of height L1 at an arbitrary monitoring distance is formed on the light receiving surface of the CCD 12 by the lens 10. For example, if the photographing magnification of the lens 10 is 100 times and the light receiving height of the CCD 12 is L2 = 2.5 cm, the height L1 of the monitoring area is 2.5 cm. That is, with respect to the photographing magnification of the imaging lens 10, the height L2 of the light receiving surface of the CCD 12 and the height of the monitoring area at an arbitrary monitoring distance.
The following relationship is established with L1.

L1 = (magnification) × L2 (1) However, L1: Height of monitoring area L2: Height of light receiving surface of CCD Next, as shown in FIG. 2, the height direction of the image stored in the frame memory 18 Distance in the monitoring area per cycle (per two divided areas) based on the number of divisions N, for example N = 10
L0 is L0 = 2 · L1 / N (2) where N is the number of divisions. For example, since the height L1 of the monitored area in the formula (1) is L1 = 2.5 m and N = 10, the distance L0 in the monitored area necessary to obtain the frequency signal of one cycle from the split screen is L0. = 50 cm.

Therefore, the relational expression of V = L0 · f (3) is established between the frequency f detected by the arithmetic control unit 20 and the moving speed V of smoke or flame.

If the moving speed to judge a fire is 0.5 m / sec from the relation of this expression (3), L0 = 50 cm, so the threshold frequency fr = 1 Hz is set and detection of 1 Hz or more is detected. Judge that the frequency is a fire.

Furthermore, from the above formula (1), the height L1 of the monitoring area is the lens 10
Since it changes according to the in-focus position of the subject due to the, the lens 10 is brought into focus by auto-focusing against the rise of smoke and flames caused by a fire that occurred at any position, and the monitoring area is determined from the shooting magnification at the time of this focus. Calculate the height L1 of the
The distance L0 for obtaining the frequency component of one cycle in the monitored area is calculated from the formula, and the detected frequency is converted to the normalized frequency so that the distance per cycle is the same, and fire judgment is performed. .

Of course, at the same time as autofocusing, the scanning in which the focus position of the imaging lens 10 is switched stepwise within a range of a predetermined monitoring distance is repeated, and the frequency is normalized from the amount of movement per detection frequency cycle based on the imaging magnification at that time to obtain the frequency. You may make a fire decision.

In the above embodiment, the image information of one screen is displayed in the height direction by N
Although it is divided, a plurality of points in the height direction may be picked up with a predetermined width at a predetermined distance apart from each other.

[Effects of the Invention] As described above, according to the present invention, an image change due to the rising speed of smoke or flame due to a fire is extracted from the video information of the monitoring area, converted into frequency information corresponding to the rising speed, and the fire is extracted. Can be determined, and higher reliability can be realized by combining with, for example, the conventional flame brightness determination.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention; FIG. 2 is an explanatory diagram of screen division for generating frequency information according to the present invention; FIG. 3 is an operation waveform diagram showing a principle of generating frequency information according to the present invention; FIG. 4 is a circuit diagram showing an embodiment of a hard logic for obtaining the operation waveform of FIG. 3; FIG. 5 shows the relationship between the monitoring area and the moving distance on the CCD for the magnification of the taking lens in the present invention. It is the explanatory view shown. 10: Lens 12: CCD 14: CCD drive circuit 16: AD converter 18: Frame memory 20: Arithmetic control unit (CPU) 22: Fire determination unit 24: Moving object (smoke or flame)

Claims (1)

(57) [Claims] 1. A means for imaging a fire monitoring area; a frequency information generating means for generating frequency information according to a moving speed of smoke or flame rising in the imaging area based on image information obtained from the imaging means. A fire judging means for judging a fire by comparing the frequency generated by the frequency information generating means with a predetermined threshold frequency;