JP3363044B2 - Fire detection method and apparatus in high temperature heat treatment process - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for industrially high-temperature heat treating a member such as a metal or a ceramic, and the heat-treated product is ignited by a trouble in the heat-treatment process or the heat-treated product is easily burned in the vicinity thereof. The present invention relates to a fire detection method and a fire detection device in a high-temperature heat treatment process, which can quickly and accurately detect the occurrence of a fire when it comes into contact with an object and ignites.

[0002]

2. Description of the Related Art Conventionally, as a system for monitoring an abnormal situation such as a fire using a CCD camera, for example, a CCD camera for imaging a monitoring section, a plurality of image memories for storing imaging information of the camera, and a CCD The CCD camera includes an infrared cut filter that passes only light having a specific wavelength or less at a normal time, and a plurality of filters that pass through the filter. Allows only light of a specific wavelength or less to pass when changes in brightness or differences between images occur over time,
Alternatively, a system in which a filter that cuts only light in a specific wavelength band is switchably mounted (Japanese Patent Publication No. 3-65075)
Or a fire equipped with a light source that radiates infrared rays and a CCD that is sensitive to the infrared rays, and a Fresnel lens made of polyethylene that projects an incident light ray onto the CCD and transmits infrared rays Detection device (JP-A-4-
No. 241094) has been proposed. However,
The former uses a monochrome CCD camera that captures only the luminance signal, and the infrared filter targets only high-temperature objects, so even if the light in a specific wavelength band is blocked, natural light or artificial light sources in all wavelength bands are used. There is a limit to prevent malfunction. On the other hand, the latter is a method of optically detecting the attenuation of infrared rays due to smoke filling the space, and does not discriminate the flame by image processing.

As fire detecting means using image processing by a color CCD camera, an image pickup means for picking up an image of a surveillance area and a range of a flame in which a luminance signal included in the image picked up by the image pickup means exceeds a predetermined level. Flame contour extracting means for extracting as a contour, temperature detecting means for detecting at least the temperature distribution in the flame contour extracted by the flame contour extracting means, distance measuring means for measuring the distance to the fire source, and flame contour extracting means Radiant energy calculating means for calculating the radiant energy from the fire source based on the temperature distribution in the flame contour and the distance to the fire source, and the radiant energy of the fire source calculated by the radiant energy calculating means There is proposed an apparatus (Japanese Patent Laid-Open No. 5-20564) including a flame judging means for judging a fire based on the above. With this technology, R captured by a color CCD camera
Although the GB signal is image-processed, there is a problem that since it is intended only for the RGB light amount ratio, the influence due to the disturbance is large and the misjudgment determination is easily caused.

On the other hand, as an apparatus for extracting an image of a color designated by a video signal picked up by a color image pickup apparatus, an RGB signal from a color CCD camera is used by a computer for hue, saturation, brightness, hue angle, hue length, etc. A device for extracting a color image and a method for determining the color order by converting the color component into a component and comparing with the reference color (Japanese Patent Publication No. 6-70590, 7).
-92401, JP-A-7-49269, 7-1984
No. 91, etc.) has been proposed. Although this device can quickly and easily extract the reference color, its application to the detection of a fire has not been clarified.

[0005]

Generally, in the process of heat-treating an intermediate member such as metal or ceramics by a heating furnace in a parts factory, for example, in the process of heat-treating steel members such as gears, various rods, springs, etc. Due to a trouble, the heat treatment member ignites, falls from the transfer device to the floor while the high temperature heat treatment member moves, or comes in contact with easily combustible substances such as oil, paper, plastic, or wood adhering to the floor or equipment. May ignite and cause a fire. When fire detection is performed in such an environment, it is often difficult to distinguish between red flames emitted from high-temperature heat-treated materials in the monitoring area and leaked flames from the heating furnace, and flames caused by a fire. If the heat treatment equipment is complicated and the illumination and external light are irregular, these ambient lights may be mistaken for a fire.

The present inventors have conducted research on means for accurately detecting the occurrence of a fire in such an environment. As a result, the color obtained by monitoring the high temperature heat treatment process with a plurality of color CCD cameras. Focusing on the fact that when an image is converted to chromaticity coordinates, the chromaticity exhibited by the high-temperature heat-treated product becomes different from the ambient light such as illumination or external light, only the chromaticity region of the heat-treated product is separated. We found that the fire occurrence can be accurately detected from the behavior of this chromaticity region.

The present invention was developed on the basis of this finding, and its purpose is to provide a high-temperature heat-treated material which can prevent a fire caused by ignition of a heat-treated material in a step of industrially high-temperature heat-treating a member such as metal or ceramics. Distinguish from the glowing light emitted, the leakage flame of the heating furnace, or the external light such as lighting or sunlight,
It is an object of the present invention to provide a fire detection method and device capable of accurately detecting a fire.

[0008]

A fire detection method in a high temperature heat treatment process according to the present invention for achieving the above object is to monitor a predetermined visual field range of the high temperature heat treatment process sequentially by a plurality of color CCD cameras. Each pixel of the obtained color image is converted into chromaticity coordinates, only the specified chromaticity area is taken out from the surveillance image, and the shape or change in shape of the chromaticity coordinates is recognized by the fire recognition logic that differs for each surveillance image. The feature of the configuration is to detect a fire.

Further, the fire detection device includes a plurality of color CCD cameras for monitoring a predetermined visual field range of a high temperature heat treatment process, a camera switcher for switching a color image screen at regular intervals, and a color image for each pixel. Converts to chromaticity coordinates and extracts only the chromaticity area to be monitored, and an image processing device that detects the shape or shape change of chromaticity coordinates according to the logic corresponding to the monitoring area, and an alarm signal that detects a fire occurrence and outputs an alarm signal. And a warning device that operates.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS It is known that when metal or ceramics is heated to a high temperature, red hot light is emitted and the color tone changes depending on the heating temperature. The relationship between this temperature and the color tone is on a black body locus in chromaticity coordinates. It can be shown by the relationship between the position and the temperature. Focusing on this point, the present invention replaces the color tone of each part in the screen of the color image with the coordinate value (x, y) on the chromaticity coordinates, and near the temperature range indicated by the heat-treated product on the black body locus. The part in is recognized as a heat-treated product. The color tone of a fire when a fire occurs always includes the color tone of the heat-treated material, regardless of the temperature distribution, and the heat-treated material and the flame at the time of the fire have the same distribution range on the chromaticity coordinates. Will belong to.

Therefore, for example, even when the heat-treated material comes into contact with the surrounding object and ignites, it is possible to simultaneously recognize the two with the same chromaticity value, and also the sunlight, welding light, lighting, etc. As shown in Table 1, the chromaticity exhibited by the external light and the chromaticity exhibited by the heat-treated material are significantly different from each other, and therefore the external light is not erroneously determined as a fire.

[0012]

[Table 1]

That is, as can be seen from Table 1, the chromaticity coordinates (x,
y) values are approximately (0.5, 0.3) to (0.7, 0.
Since it is in the range of 4) and is clearly different from the chromaticity coordinate values of external light such as sunlight, welding light, and illumination, it is possible to easily extract only the chromaticity region of the flame. Further, the conversion of each pixel of the color image into the chromaticity coordinates can be calculated at high speed by the CPU from the three primary color values of the color image. The chromaticity coordinate values are R, G, B (R; wavelength 700 nm, G;
Wavelength 546.3nm, B; wavelength 435.8nm).

With respect to the extracted chromaticity area, the shape or shape change of the chromaticity coordinates is recognized according to the fire recognition logic that differs for each object within the observation field of view, that is, for each monitoring image. (1) High-temperature object recognition and fire recognition logic: In order to detect a fire that occurs when a heat-treated material comes into contact with oil or flammable objects, it is necessary to first recognize the high-temperature object in the screen from the chromaticity value. . That is, the range of the chromaticity coordinates of the high temperature object shown in Table 1 is filed in advance in the image processing apparatus, and the chromaticity of each point of the color image is collated with this file to determine the matched portion as the heat treatment material. . In this way, the high temperature region corresponding to the heat-treated material is extracted from the color image. Fire detection is performed using the shape and shape change of the area corresponding to the heat-treated material. Since the flame shows the same chromaticity as the heat-treated material,
For example, when a fire occurs, the high temperature area rapidly increases and the shape changes. Further, when the high-temperature region suddenly disappears from the field of view or suddenly appears, it indicates that the heat-treated material or powder has fallen and deviates from the normal trajectory, and it is determined that the conveyance is abnormal. At this time, the content and degree of the shape change, the rate of the shape change, and the like are set with parameters such as the arrangement of the device in the field of view and the moving state of the heat treatment object.

(2) Combined use of process signals: In the high temperature heat treatment step, there are many objects having the same chromaticity other than the heat treated object. For example, the inside of the heating furnace is at a high temperature, and the flame leaking from the heating furnace and the chromaticity exhibited by the brick inside the heating furnace are the same as those of the heat-treated product. In such a case, the open / close signal of the heating furnace door is transmitted from the process control computer and linked with this control signal to prevent misidentification of a fire. As the process signal, signals of various sensors and analytical instruments can be used together with the sequence signal of the computer.

The present invention is based on a multi-camera system in which the fire recognition logics described above are appropriately combined to form an optimum logic according to the surveillance area monitored by each camera. It is possible to accurately detect the occurrence of a fire. The reliability can be further improved by applying a logic having a learning function to optimize the parameters for fire detection.

[0017]

Embodiments of the present invention will be described below in detail by taking as an example a case where steel members such as gears, rods and springs are continuously subjected to high temperature heat treatment.

FIG. 2 is a heat treatment step diagram schematically showing the step of conveying the heat-treated member. In FIG. 2, the heat-treated product 2 such as gears, rods, and springs automatically loaded into the heating furnace 1 is opened and closed by the arm 5 of the first robot 4 by opening and closing the door 3 of the heating furnace 1 at regular intervals. It is taken out in a state of being heated to a high temperature and placed on the intermediate stand 6. Next, the arm 8 of the second robot 7 grips the heat-treated product 2 on the intermediate placing table 6 and carries it to the cooling table 9, where it is cooled to a predetermined temperature or lower, and then carried out to the product storage area.

In this process, various types of fires as shown below occur. Fire near the heating furnace door; flame may leak to the outside from the heating furnace door, causing a fire by contacting surrounding objects. Fire caused by falling of the heat-treated material; the heat-treated material grasped by the arm of the first robot is once placed on the intermediate table and then conveyed to the cooling table by the arm of the second robot. If the condition is not good, the heat-treated product will drop on the floor. The heat-treated product that has fallen onto the floor may come into contact with flammable materials around it or oil that adheres to the floor, causing a fire. Fire of the intermediate stand; if the first robot and the second robot are out of coordination, the heat-treated material will not be transferred smoothly,
The heat-treated product may accumulate on the intermediate table and cause a fire. Robot fire: If oil adheres to the arm grip of the robot, it may ignite and cause a fire.

With respect to these fire occurrences, the fire occurrence is recognized by the following logic. (1) Transport abnormality monitoring logic (L1) for the heat-treated product; abnormality in the transport operation that cannot be identified by the diagnostic function of the robot itself, for example, if the placement of the heat-treated product on the intermediate table is incorrect, the second robot will The heat-treated product cannot be grasped accurately. In such a case, the intermediate stand is monitored by a color CCD camera, and when the heat-treated product is placed on the middle stand, the shape of the heat-treated product is recognized by the sequence signal from the robot.
Determine if the heat-treated product is placed in a proper state. In addition, when a fire occurs on the intermediate table, the shape of the high temperature region changes significantly, so that the fire can be accurately detected.

(2) Ignition monitoring logic (L2) due to the fall of the heat-treated material or the powder on the floor; the heat-treated material or the powder falls from the transfer line and falls to the floor, and the oil adhering to the floor May cause fire by contact with easily combustible materials. In such a case, when a high-temperature object appears in the field of view of the camera that monitors the floor, it is determined that the high-temperature material has fallen and an alarm signal is issued. Further, when a fire occurs, the shape of the high temperature region changes abruptly, so that the fire occurrence is detected at this point. In this monitoring area, logic is used to recognize the occurrence of a fire by observing the occurrence of a high temperature area and a sudden change in shape.

(3) Robot arm grip ignition monitoring logic (L3): The oil adhering to the robot arm may be ignited. In this case, the parallax is generated when the heat-treated material moves within the visual field. Due to this, the size of the high-temperature region gradually decreases as the heat-treated object moves away from the camera, and conversely, the high-temperature region gradually increases when approaching. When the robot arm ignites from the grip portion holding the heat-treated product in such a state, the area of the high temperature portion rapidly increases. Therefore, a fire is detected by this increase in area.

(4) Ignition monitoring logic from the furnace door (L
4); When the door of the heating furnace is open, the high temperature inside of the furnace and the leaked flame enter the field of view, and it is erroneously determined that a fire has occurred. In such a case, the shape of the high temperature region shown when the furnace door is opened is stored, and the opening / closing signal of the furnace door is input to the image processing device to specify the high temperature region in advance for the time the furnace door is open. As long as the indicated shape is shown, a fire is not recognized, and if a high temperature area is detected after the furnace door is closed, the logic to judge a fire is used.

A system configuration diagram illustrating a fire detection device of the present invention is shown in FIG. FIG. 1 shows a case in which six color CCD cameras 10 are arranged, and the color CCD cameras 10 are sequentially switched by the camera switcher 11 every 0.2 seconds to monitor the entire heat treatment process. In this case, by connecting a video monitor in parallel with the camera switcher 11 and monitoring the monitoring area, the entire field of view can be monitored at intervals of 1.2 seconds.

The color video signals sequentially sent from the six cameras are sent to the image processing device 12, and the color CCD camera 10
The switching signal is used as a confirmation signal of the monitoring position by the computer of the image processing device 12. In this way, the video signals sequentially transmitted from the six color CCD cameras can judge the fire occurrence by the logic corresponding to each of the monitoring areas described above, and when the fire occurrence is detected, the alarm device 13 is immediately activated. Outputs an alarm signal. In this system, Table 2 shows the relationship between the location of each color CCD camera and the monitoring target and the above fire recognition logic.

[0026]

[Table 2]

Table 3 shows an example of the result of detecting the fire in the high temperature heat treatment process by the above system and the fire recognition logic.

[0028]

[Table 3]

Further, FIG. 3 illustrates the shape change of the high temperature region when the floor is monitored by the camera number 3 and the fire occurrence is detected by the fire recognition logic L2. FIG. 3 shows the high temperature region by the long axis and the short axis and shows the change over time, and it can be seen that both the long axis and the short axis rapidly increase from the time when the fire occurs.

[0030]

As described above, according to the fire detection method and the fire detection apparatus of the present invention, each pixel of the image obtained by monitoring with a plurality of color CCD cameras for each predetermined visual field in the high temperature heat treatment process. Is converted to chromaticity coordinates, and only the chromaticity area specified in advance is taken out, and the fire occurrence is detected by recognizing the shape and changes in the chromaticity coordinates based on the fire recognition logic that differs for each monitoring image. Therefore, it is possible to detect the fire occurrence promptly and accurately without misidentifying it as a leaking flame from the heating furnace, ambient light such as illumination, or external light. Therefore, it is extremely useful as a fire detection method and device in a process of industrially heat treating a member such as metal or ceramic at a high temperature.

[Brief description of drawings]

FIG. 1 is a system configuration diagram illustrating a fire detection device of the present invention.

FIG. 2 is a heat treatment step diagram schematically showing a step of conveying a heat-treated member.

FIG. 3 is a graph exemplifying a relationship between a shape change in a high temperature region and elapsed time when a fire is detected.

[Explanation of symbols]

1 heating furnace 2 Heat-treated products 3 doors 4 first robot 5 Arm of the first robot 6 Intermediate table 7 second robot 8 Second robot arm 9 Cooling stand 10 color CCD camera 11 camera switcher 12 Image processor 13 Alarm device

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI G08B 21/00 G08B 21/00 AE H04N 7/18 H04N 7/18 N (72) Inventor Noboru Sasaki Toyota-cho, Toyota City, Aichi Prefecture No. 1 Toyota Motor Co., Ltd. (72) Inventor Motochika Nakamura No. 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd. (56) Reference JP-A-3-254000 (JP, A) JP-A-62 -284664 (JP, A) JP-A-9-167286 (JP, A) JP-A-7-296068 (JP, A) JP-A-6-6797 (JP, A) (58) Fields investigated (Int.Cl) . ⁷ , DB name) G08B 17/00 G01J 1/02 G01J 5/60 G08B 17/06 G08B 21/00 H04N 7/18

Claims (2)

(57) [Claims] 1. A plurality of color CCD cameras are used to sequentially monitor a predetermined visual field range of a high temperature heat treatment process, each pixel of the obtained color image is converted into chromaticity coordinates, and designated in advance from the monitor image. A fire detection method in a high-temperature heat treatment process, which comprises detecting only a chromaticity region and recognizing the shape or shape change of chromaticity coordinates by different fire recognition logic for each monitoring image to detect a fire occurrence. 2. A plurality of color CCD cameras for monitoring a predetermined visual field range of a high temperature heat treatment process, a camera switcher for switching a color image screen at regular time intervals, and converting each pixel of the color image into chromaticity coordinates. It consists of an image processing device that takes out only the chromaticity region to be monitored and detects the shape or shape change of chromaticity coordinates according to the logic corresponding to the monitoring region, and an alarm device that detects a fire occurrence and outputs an alarm signal. A fire detection device in a high temperature heat treatment process, which is characterized in that