JPH076821B2 - Liquid amount detector - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting the amount of liquid inside an opaque container which cannot be seen by a visible camera.

[0002]

2. Description of the Related Art Liquids such as various kinds of drinking water and chemicals are often stored or transported in cans, bottles or plastic containers. In order to put the liquid in these containers, the liquid is injected into the containers by an automatic injector while sending the containers on the production line. In the liquid injection by the automatic injector, the injected liquid amount may increase or decrease with respect to a predetermined value due to a nozzle clogging of the automatic injector, a measurement error of the liquid amount, or the like. This increase / decrease in the amount of injected liquid does not cause much trouble when the liquid to be injected is drinking water or the like. However, when the liquid is a chemical liquid or the like, it is required that a predetermined amount of liquid is accurately injected.

Therefore, after injecting the liquid into the container, the amount of liquid in the container is inspected. When the container is transparent, the upper end of the liquid is imaged from the side of the container with a visible camera, and it is inspected whether the injected liquid amount is within the specified range. When the container is opaque, it cannot be imaged with a visible camera, so the amount of liquid is inspected by applying ultrasonic waves to the liquid surface from directly above the container and measuring the return time of the reflected wave.

[0004]

In the liquid level inspection method using ultrasonic waves, since ultrasonic waves must be applied to each container, it takes time to perform the inspection. It was also the cause of the slowdown. Further, when the mouth of the container is small, it is difficult to apply ultrasonic waves to the liquid surface through the opening, and it is impossible to inspect the amount of liquid with ultrasonic waves. As described above, the conventional liquid amount detection device has a problem to be solved. An object of the present invention is to provide a liquid amount detection device capable of quickly detecting the amount of liquid in an opaque container and detecting the amount of liquid in the container even if the container has a small opening.

[0005]

The present invention has been made to solve the above-mentioned problems remaining in the prior art, and a plurality of infrared-transparent opaque containers filled with a liquid are placed in a line in the transport direction. Transporting means for intermittently transporting the plurality of opaque containers, heat radiating means having planar heat radiating regions arranged substantially parallel to the rows of the plurality of opaque containers, and the plurality of opaque containers with the heat radiating regions as a background. And an infrared camera disposed so as to fit within the field of view, and the infrared camera captures an image during a period in which the transport means stops transporting.

[0006]

In the present invention, an infrared image of the liquid in the opaque container is obtained by the means described above, and the amount of the liquid is detected from the infrared image. The container is photographed by the infrared camera with the planar heat radiating region of the heat radiating means positioned on the background of the container. Infrared transparent material for the container (eg plastic)
By using, an infrared image of the liquid in the container can be obtained from the infrared camera. By setting the container to a known fixed shape and predetermining the path along which the container is conveyed and the position of the infrared camera, the amount of the liquid can be detected from the height of the liquid in the infrared image. The conveying means conveys the container by an intermittent drive system in which the advance and stop are periodically repeated, and the infrared camera takes an image while the conveying means stops the conveying, so that there is no flow from the infrared camera. You can get a good image.

In the present invention, an image of the liquid is formed by an infrared camera while the containers holding the liquid are continuously conveyed in a line, and the amount of the liquid is detected from the image. In this method, the images of the respective liquids in the plurality of containers can be instantly formed in one shot, and the liquid amounts in the plurality of containers can also be instantaneously detected. Compared to the conventional method of detecting the amount of liquid in each container by irradiating ultrasonic waves from each opening with ultrasonic waves, the amount of liquid can be detected in multiple containers at one time. The apparatus of the present invention can remarkably improve the liquid amount detection speed. Further, in the present invention, since infrared light is transmitted through the container, the amount of liquid in the container can be detected regardless of the size and presence of the opening in the container. Also in this respect, the application range of the present invention is significantly wider than that of the conventional method in which the liquid amount cannot be detected in a container having a small opening or no opening.

[0008]

The present invention will be described in more detail with reference to the following examples. FIG. 1 is a conceptual diagram showing an embodiment of the present invention. In the figure, 1 is a heater panel, 2 is an infrared camera, 3
Is an analog / digital (A / D) converter, 4 is a liquid amount calculating means, 5 is a display device, 6 is a judging means, 7 is an opaque container,
8 is a belt conveyor.

The heater panel 1 is formed by arranging nichrome wires on the back surface of a thin metal plate at narrow intervals. The surface of the heater panel 1 forms a planar heat radiation area. The containers 7 are placed in a line on the upper surface of the belt conveyor 8. Container 7
The column direction corresponds to the conveyance direction of the belt conveyor 8, and the surface of the heater panel 1 is parallel to the column direction of the containers 7. The belt conveyor 8 alternately advances and stops, and intermittently conveys the container 7. The infrared camera 2 is installed at a position where the plurality of containers 7 are included in the field of view with the heater panel 1 as a background. In FIG. 1, nine containers 7 are placed as a group in a row on the belt conveyor 8, and the infrared camera 2 includes all nine containers 7 in the visual field. The infrared camera 2 two-dimensionally scans and detects infrared rays radiated from the object to be photographed in proportion to its temperature, and generates a temperature distribution image of the object. Infrared camera 2
Is imaged during a stop period of the belt conveyor 8 which is intermittently conveyed. By doing so, a clear temperature distribution image without flow can be obtained. The video signal of this temperature distribution image is an analog signal. The container 7 is made of opaque plastic and transmits infrared rays. Since the liquid in the container 7 absorbs infrared rays considerably, the infrared image obtained from the infrared camera 2 clearly distinguishes the container 7 from the liquid. FIG. 2 is a diagram showing an analog image obtained by displaying the output of the infrared camera 2 on a display device such as a CRT. The raster scan direction in this figure is the x direction.

The A / D converter 3 binarizes the analog temperature distribution image signal and outputs a digital temperature distribution image signal.
In this binarization, the liquid is digitized into "1" and the container and background are digitized into "0". The liquid amount calculating means 4 is a microcomputer, processes the digital temperature distribution image signal to calculate the liquid amount of each container 7, and outputs the liquid amount to the display device 5 and the judging means 6. The liquid amount calculation means 4 includes an image memory, and first stores the input temperature distribution image data in the image memory by the run length method. Next, the temperature distribution image data is read from this image memory, the image of each container 7 is cut from the data, and the liquid amount for each container is calculated. The method of calculating the liquid volume from the run length data will be described below.

FIG. 4 is a diagram showing an example of a two-dimensional image and run length data representing the two-dimensional image. The run length method is one of the methods for encoding an image. Now, if the same white pixel continues as a binary image,
The number of consecutive pixels is represented by (0, n). Conversely, if the black background continues for m pixels, it is expressed as (1, m). FIG. 4 exemplifies data in the case where nine rows of pixel columns obtained by raster scanning are represented by the run length method.

In the temperature distribution image data read from the image memory of the liquid amount calculating means 4, the liquid is recognized as "1" and the container and the background are recognized as "0". Therefore, in the image data stored as shown in FIG. 4, the number m of "1" s continuous in the x direction represents the number of liquid pixels. The height of the liquid corresponding to one pixel is predetermined by the distance between the infrared camera 2 and the container 7. Therefore, the height data for one pixel is input to the liquid amount calculation means 4 as the unit pixel height a and stored in advance,
By calculating am, the height h of the liquid can be obtained. Since the container 7 has a cylindrical shape and the bottom area s thereof is known, the bottom area s is input and stored in the liquid amount calculating means 4 in advance. The liquid amount calculation means calculates hs = ams to obtain the liquid amount v. In order to obtain the liquid volume v for each container 7, the liquid volume calculation means 4 uses the temperature distribution image data stored in the container 7
It is necessary to separate the liquid for each container and obtain the number of pixels m of the liquid for each container 7. As is clear from the analog image shown in FIG. 2, since the liquids in the containers 7 are arranged at intervals, the “0” data and the “1” data alternately appear in the y direction. When the value is found, since the portion of the "1" data at x is liquid, it is possible to easily separate each container 7. The liquid amount calculation means 4 is a container 7
The liquid amount for each is calculated and output to the display device 5 and the determination means 6. The liquid amount calculation means 4 also outputs digitized temperature distribution image data to the display device 5.

FIG. 3 is a diagram showing an image displayed on the display device 5. In the figure, what is shown in the form of a bar graph is a digital image showing the liquid in each container 7, and the two-digit number shows the amount of each liquid. Judgment means 6 is for each container 7
The liquid amount for each container is compared with the upper and lower limits of the allowable liquid amount, and it is determined for each container 7 whether the liquid amount is within the allowable limit. When it is determined that the liquid amount is out of the allowable limit, the improper container data indicating the number of the container from the front of the belt conveyor 8 is output. This inadequate amount container data is given to the defective product removing device provided on the downstream side of the heater panel 1 along the belt conveyor 8. The defective product removing device removes the container indicated by the unsuitable amount container data from the belt conveyor 8.

In the above-described embodiment, since the heater panel 1 is arranged in the background of the container 7, the temperature distribution image obtained by the infrared camera 2 clearly distinguishes the liquid part and the other part, By binarizing with the A / D converter 3, the image of the liquid can be converted into "1" without error. Therefore, in this embodiment, the height of the liquid can be accurately measured, and the liquid amount can be detected with high accuracy. Also, in this example,
Since the liquid amount of the nine containers can be instantly detected by one image pickup by the infrared camera, the liquid amount can be detected even when the belt conveyor 8 conveys the container 7 at high speed. Furthermore, since the liquid amount is detected based on the difference in infrared transmittance between the container and the liquid,
The size of the container opening and the presence or absence of the opening have no effect on the liquid amount detection.

FIG. 1 shows an example in which the analog temperature distribution image obtained by the infrared camera 2 is digitized by the A / D converter 3 and the liquid volume of each container is automatically calculated from the digitized temperature distribution image. showed that. However, the present invention is not limited to the embodiment of FIG. For example, an analog temperature distribution image output from the infrared camera 2 is displayed on a display device as shown in FIG. 2, the height b of the liquid on the screen is visually measured from the liquid image 72, and a known ratio k is calculated. The actual height h of the liquid is calculated by multiplying b, and the bottom area s of the container is multiplied by h,
The present invention can be implemented by a method of calculating the liquid volume v.

[0016]

As described above in detail with reference to the embodiments, according to the present invention, the heat radiating means having the planar heat radiating region is arranged substantially in parallel with the plurality of infrared transmitting opaque container rows. The plurality of opaque containers are imaged at once with an infrared camera against the background of the heat radiation region, and the liquid amount of each opaque container is calculated to determine whether the liquid amount is acceptable or not. It is possible to provide a liquid amount detection device which can detect the amount of liquid rapidly and can detect the amount of liquid even if the container has a small opening or does not have an opening.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an embodiment of the present invention.

FIG. 2 is a diagram of an image obtained by displaying an analog temperature distribution image output from the infrared camera 2 in the embodiment of FIG. 1 on a display device such as a CRT.

FIG. 3 is a diagram showing an image displayed on a display device 5 in the embodiment of FIG.

FIG. 4 is a diagram showing an example of a two-dimensional image and run length data representing the two-dimensional image.

[Explanation of symbols]

 1 Heater Panel 2 Infrared Camera 3 Analog / Digital Converter 4 Liquid Volume Calculation Means 5 Display Device 6 Judgment Means 7 Container 8 Belt Conveyor

Claims (2)

[Claims] 1. A transport means for placing a plurality of infrared-transparent opaque containers into which liquid has been injected in a transport direction in a row and intermittently transporting the plurality of opaque vessels, and a plurality of opaque vessels arranged substantially parallel to the row. A heat radiation means having a planar heat radiation area; and an infrared camera arranged so that the plurality of opaque containers are within the field of view with the heat radiation area as a background, the infrared camera stopping the transportation in the transportation means. A liquid amount detection device characterized by imaging during a period. 2. Conveying means for placing a plurality of infrared-transparent opaque containers filled with a liquid in a line in a conveying direction and intermittently conveying them, and arranged substantially parallel to the line of the plurality of opaque containers. A heat radiating means having a planar heat radiating region, an infrared camera arranged so that the plurality of opaque containers are within the field of view against the background of the heat radiating region, and each of the infrared camera receiving an output video signal of the infrared camera. Liquid amount calculation means for individually calculating the liquid amount in the opaque container, and comparing the liquid amount output from the liquid amount calculation means with a predetermined reference value to determine whether the liquid amount is acceptable or not for each opaque container. A liquid amount detecting device, wherein the camera captures an image during a transportation stop period of the transportation means.