JP2005087873A - Foreign substance removing method and its apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a foreign substance removing method and its apparatus hardly affected by noises. <P>SOLUTION: A conveyor has light transmitting property, and a detection device 3, a determination device 4 and a sorting device 5 are provided along the conveyor 1 having the transmitting property in this order from the upstream side. The detection device 3 irradiates a object to be treated with light emitted at the lower part of the conveyer 1, a monochrome camera 9 photographs the detection area of the conveyor 1 surface, and the detection device 3 detects the intensity of the light passing through the object to be treated included in the area. The determination device 4 divides the photographed data into areas of large light intensity and small light intensity for every region of the detected area. When the intensity of the detected light is equal to or less than a predetermined value, the object to be treated included in the area is determined to be the foreign substance, and a removing command for all the objects to be treated included in the region is outputted. The sorting device 5 discharges the objects to be treated included in the region to the outside of the process, on receiving the removal command. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an apparatus for removing foreign substances contained in an object to be processed, and more particularly to a method and apparatus for removing foreign substances contained in a pulverized product prior to pulverizing and recycling used PET bottles. Is.

  An apparatus for removing foreign matter from an object to be processed or an apparatus for separating a target article from foreign objects is used in various technical fields, and a camera is used as a means for selecting an object and foreign objects from an object to be processed. For example, Patent Document 1 and Patent Document 2 describe such apparatuses.

  Patent Document 1 is an invention that aims to perform bottle color determination with high accuracy by excluding labels, dirt, lids, etc., even if the shape and size of the bottle are not constant. A transparent screen is provided on the way to another collection box, light is applied to the bottle on the transparent screen, and the transmitted light of the bottle is photographed with a camera.

  The brightness distribution in the bottle length direction is obtained from the image obtained by the camera with the image processing device, a brightness threshold is set for the brightness distribution in the bottle edge length direction, and a range having a brightness value below the threshold is set in the bottle. Next, the range having the maximum luminance in the bottle length direction in the luminance distribution in the bottle center length direction is determined as the color determination target area, and this area is determined. The luminance value of each RGB color component is obtained and given to the color determination unit.

  Patent Document 2 is intended for automation of foreign matter removal work in the tea processing line, and is disposed between tea machines in the tea processing line, and normal operation for conveying tea leaves in the direction of the processing line; A belt conveyor that can switch the reverse movement of conveying tea leaves in another direction, a monitoring camera that monitors by imaging the tea leaves on the belt conveyor, and detection of contamination from the image captured by the monitoring camera It comprises a detecting means and a control means for switching the drive pulley to reverse when a foreign matter is detected by the detecting means.

  Transparent bottles and colored bottles are used for PET bottles, and transparent bottles are easy to recycle. Colored bottles have a limited purpose for recycling. To recycle, the transparent and colored ones are selected.

  If this is just a bottle sorting, even if there is a problem of peeling off the label, it can be sorted basically in the same manner as the apparatus described in Patent Document 1. However, in the crushed plastic bottle, the colored flakes M1 and the transparent flakes M2 are mixed, and it is difficult to sort them manually. Further, the apparatus described in Patent Document 1 cannot be selected.

  Patent Document 2 aims at automating foreign matter removal work in a tea processing line, but an apparatus for sorting flakes of PET bottles crushed in the same manner has already been put into practical use. In this apparatus, as shown in FIG. 7, a color camera 22 is installed on a conveyor 21, the workpiece M conveyed on the conveyor 21 is photographed by the color camera 22, and data of the photographed image is set in advance. Compared with the threshold value, when the processed product M is determined to be transparent flake M2, it is conveyed from the feed end of the conveyor 21 to the next process, and when it is determined that the colored flake M1 is other foreign matter, the air nozzle 23 increases the pressure. It is a mechanism that ejects air and removes it outside the process.

  However, in the case of the apparatus shown in FIG. 5, since the color camera 22 is used, a threshold value must be set for each of the three colors (R, G, R), and setting the conditions is extremely troublesome.

Moreover, even if the threshold values for the respective colors are set, the threshold values for the respective colors set in advance become noise due to the influence of dirt on the workpiece M, dirt on the transport surface of the conveyor 21 and external light. There is a problem that it is not always reliable as a criterion value for determining whether or not sorting is correct. In addition, a certain image processing is required to obtain a selection signal from image data. Furthermore, even if a crushed material of a PET bottle is selected, the object to be processed is not limited to a PET bottle, but a metal piece. In addition, there is a problem that a large amount of information is required because a label or the like attached to a plastic bottle is included, and the image processing takes a long time.
Japanese Patent Publication No. 10-62251 Japanese Patent Publication No. 2002-316100

  The problem to be solved is that the sorting accuracy is low due to the contamination of the object to be processed, the contamination of the belt conveyor, and noise such as external light, and the image processing takes a long time.

  In the present invention, in order to eliminate the influence of noise as much as possible, a monochrome camera is used, and an area (white area) in which the intensity of light as a target is obtained from image data obtained by detection processing, and light below that as a foreign object are obtained. The most important feature is binarization into a region where only intensity can be obtained (black region).

That is, the foreign matter removal method according to the present invention is a foreign matter removal method having a detection process, a determination process, and a sorting process,
The detection process is a process of irradiating a predetermined detection area with a light beam and detecting the intensity of transmitted light that has passed through the workpiece in the detection area.
The determination process is an area that includes an object to be processed that is determined as a target object within the detection area or an area that includes an object to be determined as a foreign object based on the intensity of light transmitted through the object to be processed. Is a process of outputting to the sorting process a command to exclude the object to be processed in the area determined to be a foreign object,
The sorting process is a process of excluding the object to be processed in the area determined as a foreign substance from the process based on the result of the determination process.

In the detection process, a monochrome camera shoots the workpiece that has been transported into the detection area while irradiating light from the bottom surface of the light-transmitting conveyor, and outputs the captured data to the determination process. Process
Judgment processing binarizes the image data into light intensity levels for each area in the detection area, and when the detected light intensity is less than or equal to a predetermined threshold value, It is a process that determines that a processed object is a foreign object and outputs an exclusion command for all objects to be processed included in that area to the sorting process.
The sorting process is a process of receiving an exclusion command and excluding the object to be processed included in the detection area as a foreign substance out of the process.

  The determination process is a process of outputting an exclusion command to the sorting device when the area of the region determined to be a foreign object is larger than a predetermined determination area threshold value.

  In addition, the conveyor surface included in the field of view of the monochrome camera is divided into two or more detection areas, and detection processing, determination processing, and sorting processing are individually performed for each object to be processed included in each detection area. It is.

Also has a heat treatment,
The heating process is a process of heating the object to be processed prior to the detection process and contracting the heat-shrinkable label contained in the object to be processed.

  The heat treatment is a process of separating the heat-shrinkable label attached to the object to be processed from the object to be processed by contracting the heat-shrinkable label.

Further, in the foreign matter removal apparatus according to the present invention, the foreign matter removal apparatus having a combination of a transport device, a detection device, a determination device, and a sorting device,
The conveying device is a conveyor that conveys an object to be processed in one direction, the conveyor has light permeability, and the detection device, the determination device, and the sorting device are installed in order from the upstream side along the conveyor,
The detection device consists of a light source and a monochrome camera.
The light source emits light below the conveyor and irradiates the object to be processed through the conveyor.
The monochrome camera captures the detection area defined on the conveyor surface, and detects the intensity of light transmitted through the workpiece contained in the detection area.
The determination device binarizes the light intensity detected by the monochrome camera in the detection area into the light intensity of the area determined as the target object and the light intensity of the area determined as the foreign object, and the detected light intensity However, when the light intensity of the area to be determined as the target object is less than or equal to, outputs an exclusion command for all objects to be processed included in the area to the sorting device,
The sorting device has an air nozzle installed at the feed end of the conveyor,
The air nozzle operates when receiving an exclusion command, ejects air, and excludes all objects to be processed included in a region determined to be a foreign substance out of the process.

It also has a heating device,
The heating device is installed on the upstream side of the detection device, heats the object to be processed before being detected by the detection device, contracts the heat-shrinkable label contained in the object to be processed, and further attaches it to the object to be processed. The heat-shrinkable label attached is to be separated from the workpiece by shrinking.

  The present invention uses a monochrome camera to detect an object to be processed, and obtains only the intensity (light white area) where the intensity of light as a target can be obtained and the intensity of light less than that as a foreign object. Since it is binarized into areas that cannot be processed (black areas), it is easy to set thresholds, it is less susceptible to external noise, and the sorting accuracy can be dramatically improved compared to conventional methods, and image processing Has the advantage that the waste can be effectively reused.

  The present invention uses a light-transmitting conveyor, shoots an object to be processed in a detection area conveyed on the conveyor while irradiating the lower surface of the conveyor with a monochrome camera, and sets a threshold value in advance. From the wavelength range obtained in the imaging data, the wavelength range above the threshold value to be left in the process as a selection target (white), and the wavelength range below the threshold to be excluded outside the process as an exclusion target (white) The method for removing foreign matter and its device with high sorting ability were realized.

  Embodiments of the present invention will be described with reference to the drawings, in which a plastic bottle is used as an object to be processed and a transparent bottle crush flake (transparent flake M2) and a colored bottle crush flake (colored flake M1) are selected. To do. In FIG. 1, the foreign matter removing apparatus according to the present invention comprises a combination of a transport apparatus 1, a heating apparatus 2, a detection apparatus 3, a determination apparatus 4, and a sorting apparatus 5.

  In FIG. 2, the conveying device 1 is a conveyor that conveys the workpiece M in one direction. Hereinafter, the conveying device 1 will be described as the conveyor 1. Further, colored flakes contained in the workpiece M are indicated by M1, and transparent flakes are indicated by M2. The conveyor 1 has a light-transmitting belt 6a that is stretched between a pair of pulleys 6b and 6b. In the present invention, light transmission does not matter colorless, colored, transparent, translucent or light transmission amount, but as long as shooting with a camera, the light transmission amount is as large as possible. Needless to say, it is desirable. A heating device 2, a detection device 3, a determination device 4, and a sorting device 5 are installed in order from the upstream side along the conveyor 1.

  In FIG. 2, the heating device 2 includes an infrared heater 7 with a reflection mirror, for example. The heater 7 heats the object to be processed before the object M is detected by the detection device 3 and contracts the heat-shrinkable label R contained in the object to be processed. The heat-shrinkable label R is mainly attached to a plastic bottle, but most of the label is peeled off from the crushed flakes when the plastic bottle is crushed. The label (including fragments) peeled off from the crushed flakes is shrunk as it is and rounds into a small lump. In addition, the heat-shrinkable label (including fragments) that remains attached to the crushed flakes is heated and shrunk, peeled off from the crushed flakes, and separated from the object to be processed into a small lump.

  The heating temperature by the heater 7 is detected by a temperature sensor 7a installed at the subsequent stage. The heater 7 is used when the object to be processed M contains a heat-shrinkable substance such as a label, and it is not necessary to install the heater 7 when handling a piece of a bottle without a label as the object to be processed M. .

  The detection device 3 is a combination of a light source 8 and a monochrome camera 9. The light source 8 is installed below the upper process of the conveyor 3, emits light below the belt surface of the conveyor 1, transmits the conveyor 1, and irradiates the object to be processed with light. The monochrome camera 9 is a digital camera that captures an image of a detection area A defined on the conveyor surface and detects the intensity of light transmitted through an object to be processed included in the detection area A.

  The determination device 4 includes a region including a target object determined as a target object and a target object determined as a foreign object based on the intensity of light detected by the monochrome camera 9 in the detection area A. An area is specified, and when it is determined that an area includes an object to be processed that is determined to be a foreign object, an exclusion command for all objects to be processed in that area is output to the sorting device 5 It is.

  The sorting device 5 has an air nozzle 10 installed at the feed end of the conveyor 1. In FIG. 2, PET bottle crushing flakes (transparent flakes M2 and colored flakes M1) finely crushed as objects to be processed are carried onto the belt from the upstream end of the conveyor 1. By feeding, the heating device 2, the detection device 3, the determination device 4, and the sorting device 5 are sequentially sent from the upstream side, and in each device, the heating process, the detection process, the determination process, and the sorting process are sequentially performed.

(1) Heat treatment In the heat treatment, the shredded flakes, which are the object to be processed M, are heated prior to the detection processing, pasted on a broken plastic bottle, and after crushing, the heat-shrinkable label R (debris peeled off from the shredded flakes). Is a process of thermally shrinking the heat-shrinkable label R (including fragments) that remains adhered to the crushed flakes even after crushing. The heat-shrinkable label R that has received the high heat of the infrared heater 7 is heat-shrinked to be rounded, and the label attached to the crushed flakes is heated to be shrunk and separated from the crushed flakes. This facilitates the subsequent sorting process.

(2) Detection process The detection process is a process of irradiating a predetermined detection area A on the conveyor 1 with a light beam and detecting the wavelength of transmitted light transmitted through the workpiece M in the detection area A. In this embodiment, the light from the light source 8 is irradiated to a predetermined range on the back surface of the belt 6 a through the filter 11, and the light transmitted through the belt 6 a irradiates the workpiece M sent on the conveyor 1 through the filter 12. On the other hand, the monochrome camera 9 installed above the conveyor 1 photographs the workpiece M on the conveyor 1 sent into the detection area A with the range of the field of view as the detection area A. The necessary data is the wavelength of light in the detection area 1. The photographing data is output to the determination device 4.

(3) Determination process The determination process measures the intensity of transmitted light that has passed through the object to be processed M, and is an area including an object to be processed that is determined as a target object based on the intensity of the light, or a foreign object. In this process, it is determined whether or not the processing object is an area including the object to be processed, and an instruction to exclude the object to be processed in the area determined to be a foreign object is output to the selection process. Specifically, the determination device 4 based on the photographing data of the detection device 3 determines the light intensity of the object to be processed determined as the target object (for example, the light intensity determined to be “white” color), the foreign matter, When the intensity of light in the detected area is equal to or less than the intensity of the target light, it is binarized to a lower intensity (for example, the intensity of light determined to be “black”). A command to exclude all contained objects to be processed out of the process is output to the sorting device 5.

  FIG. 3 is an image of the relationship between the wavelength of light and the intensity of light. In the detection area A, a wavelength region to be measured is set, and whether the light intensity of photographing data in the detection area is a preset wavelength region is a target or a foreign object. It is distinguished by setting the threshold value Is to the intensity of. In this example, when the intensity is higher than the threshold value Is, it is determined that the object is white (white).

  FIG. 4 is an image diagram of binarized shooting data. If a region having an intensity higher than the threshold value Is is expressed by “white” and a region having an intensity lower than the threshold value Is is expressed by “black”, the detection area A becomes a foreign substance as shown in FIG. The color is divided into a “black” area and a “white” area as a target. The exclusion command is determined based on the size of the black area as a foreign object. In this example, a threshold value Ss is set as the discrimination area, and when the area S of the black region, which is a foreign substance appearing in the detection area A, is larger than the threshold value Ss, an exclusion command is output to the sorting device 5 and black When the area S of the region is smaller than the threshold value Ss, the exclusion command is not output. The threshold value Ss can be set freely. The smaller the threshold value Ss, the higher the sorting accuracy, but the sorting process becomes conversely complicated.

  As shown in FIG. 2, by using a filter that allows only light of a specific wavelength to pass through at least one of the filters 11 and 12, it becomes difficult to receive noise from outside light and the like, and as a result, accuracy of the determination process In addition, it is possible to determine only an object to be sorted of a specific color. The selection of the presence / absence of a filter, the type of filter, the installation position, and the like is preferably determined by the installation conditions and selection conditions of the apparatus.

(4) Sorting process The sorting process is a process of sorting the workpiece M into a target object and a foreign object based on the result of the determination process. That is, the air nozzle 10 operates when receiving an exclusion command, ejects compressed air, determines that the workpiece M included in the detection area A is a foreign object, and collectively excludes it from the process. .
As a result, the foreign matter in the black region gathered in an area larger than the threshold Ss of the discrimination area, that is, most of the colored flakes M1 contained in the workpiece M in the detection area is excluded outside the process. Thus, most of the transparent flakes M2 included in the workpiece M within the detection area are left in the process.

  By performing detection processing, determination processing, and selection processing again for those excluded outside the process, a part of the transparent flake M2 included in those excluded as foreign matter is returned to the process.

  In this embodiment, an example in which a metal piece removal process is performed as necessary following the detection process is shown. The metal piece removing process is a process for detecting when a metal cap of a plastic bottle or other magnetic metal piece is contained in the object to be processed. The metal piece removing device 14 is a vibration type magnetic sensor 13. Used. When the magnetic sensor 13 detects a metal piece in the specific detection area A, a detection signal is output to the determination device 4, the processed material in the specific detection area is determined as a foreign object, and the metal piece is input to the sorting device 5. Command the removal of processed material in the detected area.

FIG. 5 is an example in which the surface of the conveyor 1 included in the field of view of the monochrome camera 9 is divided into two or more detection areas in the width direction, and detection processing is performed individually for each object to be processed included in each detection area. . In this example, the conveyor width of 80 mm and length of 25 mm is divided into three detection areas A1 to A3 having a size of 30 mm × 25 mm including an overlap portion of 5 mm in the center, and the respective detection areas A1, A2, This is an example in which a dedicated sorting device (air nozzles 10 ₁ , 10 ₂ , 10 ₃ ) is installed for each A3. By dividing the conveyor 1 into two or more within the range of its width, the accuracy of sorting can be increased.

  FIG. 6 shows the content of foreign matter in the processed material when the foreign matter containing colored flakes contained in the crushed PET bottle is manually sorted, and when sorting is performed using the device of the present invention after manual sorting. It is a graph which shows a comparison. In the manual sorting, the content rate of foreign matter was 2700 ppm, but in the case of sorting using the apparatus of the present invention after manual sorting, the sorting accuracy could be increased to 731 ppm. This value is about ½ of the reference value of 1300 ppm.

  As described above, in the embodiment, the example of selecting the transparent flakes M2 and the colored flakes M1 contained in the crushed flakes of the PET bottle has been described. If it is, what kind of to-be-processed object can be similarly separated.

It is a block diagram which shows the structure of this invention. It is a block diagram of a system showing an embodiment of the present invention. It is a figure showing the image of the relationship between the wavelength and the intensity | strength of the light detected within a detection area. It is an image figure showing the magnitude | size of the area | region where the to-be-processed object judged to be a foreign material is contained in a detection area. It is a block diagram of the system which shows other embodiment of this invention. It is a graph which shows the effect of the sorting process by this invention. It is a figure which shows an example of the conventional foreign material removal apparatus.

Explanation of symbols

1 Transport device (conveyor)
2 Heating device 3 Detection device 4 Judgment device 5 Sorting device 6a Belt 6b Pulley 7 Heater 8 Light source 9 Monochrome camera 10 Air nozzle 11 Filter (bottom)
12 Filter (top)
13 Vibration type magnetic sensor M Object to be processed M1 Colored flake M2 Transparent flake R Label A Detection area

Claims (8)

A foreign matter removal method having a detection process, a determination process, and a selection process,
The detection process is a process of irradiating a predetermined detection area with a light beam and detecting the intensity of transmitted light that has passed through the workpiece in the detection area.
The determination process is an area that includes an object to be processed that is determined as a target object within the detection area or an area that includes an object to be determined as a foreign object based on the intensity of light transmitted through the object to be processed. Is a process of outputting to the sorting process a command to exclude the object to be processed in the area determined to be a foreign object,
The foreign matter removal method characterized in that the sorting process is a process of removing an object to be processed in an area determined as a foreign substance out of the process based on a result of the determination process. The detection process is a process in which a monochromatic camera is used to photograph the object to be processed that has been conveyed to the detection area on the conveyor while irradiating light from the lower surface direction of the light transmissive conveyor, and the photographed data is output to the determination process. And
Judgment processing binarizes the image data into light intensity levels for each area in the detection area, and when the detected light intensity is less than or equal to a predetermined threshold value, It is a process that determines the processed object as a foreign object and outputs an exclusion command for all processed objects included in the area to the sorting process,
2. The foreign matter removal method according to claim 1, wherein the sorting process is a process of receiving an exclusion command and removing an object to be processed included in the detection area as a foreign matter outside the process.   3. The determination process according to claim 1, wherein the determination process is a process of outputting an exclusion command to the sorting device when the area of the region determined to be a foreign object is larger than a predetermined determination area threshold value. Foreign matter removal method.   The conveyor surface included in the field of view of the monochrome camera is divided into two or more detection areas, and detection processing, determination processing, and selection processing are individually performed for each workpiece included in each detection area. The foreign matter removing method according to claim 2. Having heat treatment,
The foreign matter removal according to claim 1 or 2, wherein the heat treatment is a treatment of heating the object to be processed prior to the detection process and contracting the heat-shrinkable label contained in the object to be processed. Method.   6. The foreign matter removing method according to claim 5, wherein the heat treatment is a treatment for separating the heat-shrinkable label attached to the object to be processed from the object to be processed by shrinking the heat-shrinkable label. A foreign matter removal device having a combination of a transport device, a detection device, a determination device, and a sorting device,
The conveying device is a conveyor that conveys an object to be processed in one direction, the conveyor has light permeability, and the detection device, the determination device, and the sorting device are installed in order from the upstream side along the conveyor,
The detection device consists of a light source and a monochrome camera.
The light source emits light below the conveyor and irradiates the object to be processed through the conveyor.
The monochrome camera captures the detection area defined on the conveyor surface, and detects the intensity of light transmitted through the workpiece contained in the detection area.
The determination device binarizes the light intensity detected by the monochrome camera in the detection area into the light intensity of the area determined as the target object and the light intensity of the area determined as the foreign object, and the detected light intensity However, when the light intensity of the area to be determined as the object is less than or equal to, outputs an exclusion command for all objects to be processed included in the area to the sorting device,
The sorting device has an air nozzle installed at the feed end of the conveyor,
The air nozzle operates when receiving an exclusion command, ejects air, and removes all objects contained in the area determined to be a foreign object out of the process. apparatus. Having a heating device,
The heating device is installed on the upstream side of the detection device, heats the object to be processed before being detected by the detection device, contracts the heat-shrinkable label contained in the object to be processed, and further attaches it to the object to be processed. 8. The foreign matter removing apparatus according to claim 7, wherein the attached heat-shrinkable label is separated from the object to be processed by being contracted.

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