Patent Publication Number: US-11033937-B2

Title: Color sorting machine

Description:
TECHNICAL FIELD OF THE INVENTION 
     The present invention relates to a color sorting machine for removing foreign matter in an object to be sorted. 
     BACKGROUND OF THE INVENTION 
     Conventionally, there has been known a color sorting machine removing foreign matter in an object to be sorted such as grain (See, for example, Patent Document 1). In this type of color sorting machine, an object to be sorted first flows down on a chute to be released into a sorting region. Next, a detection device applies light to the object to be sorted passing through the sorting region and takes a picture of the object to be sorted to produce an image, and detects foreign matter based on the image. When foreign matter is detected, a removing device ejects compressed air against the detected foreign matter to remove the foreign matter. 
     An object to be sorted of low specific gravity such as flour, however, does not pass through the sorting region at a fixed speed and on a fixed track due to the air resistance the object receives when the object is released into the sorting region. As a result, in some cases, the compressed air does not hit the detected foreign matter, with the result that the foreign matter cannot be properly removed. 
     In view of this, a color sorting machine for stably supplying the object to be sorted to a sorting region has been developed (see, for example, Patent Document 2).  FIG. 5  shows a color sorting machine which supplies an object to be sorted  200  to a sorting region (a region between transparent walls  800   a  and  800   b  and a foreign matter removing region on the downstream side thereof) by a supply device  100 . 
     The supply device  100  supplies compressed air to an air ejection portion  600  by a compressed air supply portion  400  and ejects compressed air to between a pair of transparent walls  800   a  and  800   b  from an air ejection port  500  via a line groove  700  by the air ejection portion  600 . An airflow generated by this compressed air passes between the pair of transparent walls  800   a  and  800   b.  Thus, the object to be sorted  200  is conveyed by the airflow so as to pass between the pair of transparent walls  800   a  and  800   b.  A detection device  300  consists of a light source, an optical sensor, or the like, While the object to be sorted  200  passes between the transparent walls  800   a  and  800   b , the detection device  300  optically detects foreign matter in the object to be sorted  200  through the transparent walls  800   a  and  800   b.  An ejection nozzle  900  is arranged on the downstream side of the transparent walls  800   a  and  800   b  and when foreign matter is detected, the ejection nozzle  900  ejects compressed air against the detected foreign matter to remove the foreign matter. 
     The region on the downstream side of the transparent walls  800   a  and  800   b  is enlarged in order to eject compressed air to remove foreign matter, As a result, when the airflow has passed between the transparent walls  800   a  and  800   b,  the airflow is disturbed in the downstream region. That is, in the sorting region, the airflow is unstable. As a result, in the case where the specific gravity of the object to be sorted  200  is lower than that supposed by this color sorting machine, the object to be sorted  200  is dispersed in all directions when it has passed between the transparent walls  800   a  and  800   b.  As a result, the compressed air may not hit the detected foreign matter and the foreign matter may not be properly removed. 
     PRIOR ART DOCUMENTS 
     Patent Documents 
     [Patent Document 1] JP-2011-92861 A 
     [Patent Document 2] JP-2009-22870 A 
     SUMMARY OF THE INVENTION 
     Problems to be Solved by the Invention 
     It is an object of the present invention to provide a color sorting machine capable of properly removing foreign matter even if the specific gravity of the object to be sorted is low. 
     Solution to the Problems 
     According to an embodiment of the present invention, when conveying an object to be sorted along a conveyance route, a color sorting machine sorts a predetermined object in the object to be sorted as foreign matter in a sorting region, and removes the sorted foreign matter into a removal route extending from the sorting region. The color sorting machine is equipped with a supply portion, a sorting portion, a first conveying portion, a second conveying portion, a removing portion, a detection device, a removal device, an air intake port, and a first suction device. The supply portion supplies the object to be sorted to the conveyance route. The sorting portion surrounds the sorting region, and is formed at least partially by a transparent wall. The first conveying portion surrounds the conveyance route from the supply portion to the sorting region, and is hermetically connected to the sorting portion. The second conveying portion surrounds the conveyance route from the sorting region, and is hermetically connected to the sorting portion. The removing portion surrounds the removal route, and is hermetically connected to the sorting portion. The detection device optically detects foreign matter in the object to be sorted being conveyed. The removal device ejects air against the foreign matter in the sorting region in order to remove the detected foreign matter into the removal route. The air intake port is provided in the first conveying portion or the supply portion. The first suction device is provided in the second conveying portion. In the color sorting machine, the sorting portion hermetically surrounds the sorting region except for a portion communicating with the first conveying portion, the second conveying portion, and the removing portion, and the second conveying portion hermetically surrounds the conveyance route from the sorting region to the first suction device, with the first suction device sucking in air in the conveyance route and generating an airflow heading for the second conveying portion from the air intake port via the sorting region. 
     The color sorting machine may be further equipped with a second suction device provided in the removing portion. The removing portion hermetically surrounds the removal route from the sorting region to the second suction device, and the second suction device sucks in air in the removal route and prevents backflow of foreign matter from the removal route to the sorting region. 
     According to another embodiment of the present invention, a color sorting machine is equipped with a supply portion, a sorting portion, a first conveying portion, a second conveying portion, a removing portion, a detection device, a route switching device, an air intake port, a first suction device, and a second suction device. The supply portion supplies an object to be sorted to a conveyance route. The sorting portion surrounds a sorting region, and at least a part thereof is formed by a transparent wall. The first conveying portion surrounds the conveyance route from the supply portion to the sorting region, and is hermetically connected to the sorting portion. The second conveying portion surrounds the conveyance route from the sorting region, and is hermetically connected to the sorting portion. The removing portion surrounds a removal route, and is hermetically connected to the sorting portion. The detection device optically detects foreign matter in the object to be sorted conveyed through the transparent wall. When no foreign matter is detected, the route switching device establishes communication between the sorting portion and the second conveying portion, and prohibits communication between the sorting portion and the removing portion. When the foreign matter is detected, the route switching device prohibits communication between the sorting portion and the second conveying portion, and establishes communication between the sorting portion and the removing portion. The air intake port is provided in the first conveying portion or the supply portion. The first suction device is provided in the second conveying portion. The second suction device is provided in the removing portion. In the color sorting machine, the sorting portion hermetically surrounds the sorting region except for a communicating portion between the second conveying portion and the removing portion, the second conveying portion hermetically surrounds the conveyance route from the sorting region to the first suction device, and the removing portion hermetically surrounds the removal route from the sorting region to the second suction device, with the first suction device sucking in the air in the conveyance route to generate an airflow heading for the second conveying portion from the air intake port via the sorting region, and further, the second suction device sucking in the air in the removable route to generate an airflow heading for the removing portion from the sorting region. 
     The removing portion may have a removal route chamber reducing variation in the airflow of the removal route. 
     The second conveying portion may have a conveyance route chamber reducing variation in the airflow of the conveyance route. 
     The second suction device may have a foreign matter cyclone separating foreign matter from a gas. 
     The first suction device may have a sorted object cyclone separating a sorted object from a gas. 
     The detection device may have a light source applying light to the object to be sorted through the transparent wall, a camera taking a picture of the object to be sorted to which light is applied so as to produce an image, and an analysis portion detecting foreign matter based on the image. 
     The color sorting machine may be further equipped with an opening adjusting portion adjusting an air intake amount at the air intake port. 
     Effect of the Invention 
     In accordance with the present invention, it is possible to provide a color sorting machine capable of properly removing foreign matter even if the specific gravity of the object to be sorted is low. 
     More specifically, in the color sorting machine of the present invention, air in the conveyance route is sucked in from the second conveying portion on the downstream side of the sorting portion by the first suction device, thereby generating an airflow passing through the sorting region from the first conveying portion and heading for the second conveying portion. Since the airflow is generated through suction, the airflow is stable while it passes through the sorting region, that is, when foreign matter is detected by detection device, and is removed by the removal device. As a result, even if its specific gravity is low, the object to be sorted is conveyed so as to pass the sorting region in a stable manner due to the airflow, and the removal device can eject air against the foreign matter. Thus, the color sorting machine of the present invention can properly remove foreign matter in the object to be sorted. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIG. 1  includes portion A which is a schematic sectional view of a color sorting machine according to a first embodiment of the present invention, and portion B which is an enlarged partial view of the color sorting machine of portion A. 
         FIG. 2  is an enlarged partial perspective view of the color sorting machine of  FIG. 1 . 
         FIG. 3  is a schematic sectional view of a color sorting machine according to a second embodiment of the present invention. 
         FIG. 4  includes portion A which is a schematic sectional view of a color sorting machine according to a third embodiment of the present invention, and portion B which is an enlarged partial view of the color sorting machine of portion A. 
         FIG. 5  is a schematic sectional view of a color sorting machine according to a conventional example. 
     
    
    
     DETAILED EXPLANATION OF THE PREFERRED EMBODIMENTS 
     First Embodiment 
     The first embodiment of the present invention will be described with reference to the accompanying drawings. 
       FIG. 1A  is a schematic sectional view of a color sorting machine M 1  according to the first embodiment of the present invention. The color sorting machine M 1  is equipped with a supply portion  1 , a sorting portion  2 , a first conveying portion  3 , a second conveying portion  4 , a removing portion  5 , a detection device  6 , a removal device  7 , a first suction device  8 , and a second suction device  9 . The color sorting machine M 1  conveys an object to be sorted along a conveyance route G, and while doing so, removes in a sorting region R a predetermined object in the object to be sorted as foreign matter F into a removal route D extending from the sorting region. R. 
     The supply portion  1  temporarily stores the object to be sorted, and supplies the object to be sorted to the conveyance route G. The supply portion  1  has a hopper  11 , and the object to be sorted flows out of the hopper  11  into the conveyance route G. 
     The conveyance route G has a predetermined width, and extends from the supply portion  1  while inclined downwards so as to pass through the sorting region R. 
     As shown in  FIG. 1B , the sorting region R is a region surrounded by phantom line. As described in detail below, in the sorting region R, foreign matter F in the object to be sorted is optically detected by the detection device  6 , and is removed into the removal route D by the removal device  7 . 
     The sorting portion  2  surrounds the sorting region R. The sorting portion  2  is formed by a pair of transparent walls  21   a  and  21   b,  and an opaque wall  22 . 
     As shown in  FIG 1A , the first conveying portion  3  surrounds the conveyance route G from the supply portion  1  to the sorting portion  2 , and is hermetically connected to the sorting portion  2 . The first conveying portion  3  is provided with an air intake port  32 . The first conveying portion  3  hermetically surrounds the conveyance route G from the air intake port  32  to the sorting region R. 
     The first conveying portion  3  has a chute  31  arranged in an inclined state between the hopper  11  and the transparent walls  21   a  and  21   b.  The chute  31  is formed as a rectangular duct. The object to be sorted flows down on the inclined surface of the chute  31 , whereby the object to be sorted is conveyed along the conveyance route G, and is sent to the sorting region R. The air intake port  32  is formed in the upstream portion of the chute  31 . The conveyance route G to the sorting region R is hermetically surrounded by the chute  31  except for the air intake port  32 . 
     As shown in  FIG. 2 , the second conveying portion  4  surrounds the conveyance route G from the sorting region R, and is hermetically connected to the sorting portion  2 . The second conveying portion  4  hermetically surrounds the conveyance route G from the sorting region R to the first suction device  8 . 
     The second conveying portion  4  has an upstream conveying portion  41 , downstream conveying portions  42   a  and  42   b,  and a conveyance route chamber  43 . The upstream conveying portion  41  is formed as a rectangular duct. The upstream conveying portion  41  is connected to the sorting portion  2  and the conveyance route chamber  43 . The downstream conveying portions  42   a  and  42   b  are formed as hoses. The downstream conveying portions  42   a  and  42   b  are connected to the conveyance route chamber  43  and the first suction device  8 . More specifically, the downstream conveying portion  42   a  is connected to one of opposing side walls of the conveyance route chamber  43 , and the downstream conveying portion  42   b  is connected to the other of the side walls. Thus, the conveyance route G branches off in two ways from the conveyance route chamber  43 , and then unifies at the first suction device  8 . 
     The conveyance route chamber  43  is formed as a box. The section of the conveyance route chamber  43  orthogonal to the conveyance route G is larger than the section of the upstream conveying portion  41  and the downstream conveying portions  42   a  and  42   b  orthogonal to the conveyance route G. 
     While in this example the conveyance route G branches off in two ways from the conveyance route chamber  43 , this is a mere example and should not be construed restrictively. For example, by making the volume of the conveyance route chamber  43  sufficiently large, the conveyance route G does not have to branch off from the conveyance route chamber  43 . 
     The removing portion  5  surrounds the removal route D, and is hermetically connected to the sorting portion  2 . The removing portion  5  hermetically surrounds the removal route D from the sorting region R to the second suction device  9 . 
     The removing portion  5  has an upstream removing portion  51 , downstream removing portions  52   a  and  52   b,  and a removal route chamber  53 . The upstream removing portion  51  is formed as a rectangular duct. The downstream removing portions  52   a  and  52   b  are formed as hoses. The downstream removing portions  52   a  and  52   b  are connected between the removal route chamber  53  and the second suction device  9 . More specifically, the downstream removing portion  52   a  is connected to one of opposing side walls of the removal route chamber  53 , and the downstream removing portion  52   b  is connected to the other of the side walls. Thus, the removal route D branches off in two ways from the removal route chamber  53 , and then unifies at the second suction device  9 . 
     The removal route chamber  53  is formed as a box. The section of the removal route chamber  53  orthogonal to the removal route D is larger than the section of the upstream removing portion  51  and the downstream removing portions  52   a  and  52   b  orthogonal to the removal route D. 
     While in this example the removal route D branches off in two ways from the removal route chamber  53 , this is a mere example and should not be construed restrictively. For example, by making the volume of the removal route chamber  53  sufficiently large, the removal route D does not have to branch off from the removal route chamber  53 . 
     As shown in  FIG. 1 , the detection device  6  optically detects foreign matter F in the object to be sorted conveyed through the transparent walls  21   a  and  21   b.    
     The detection device  6  has a plurality of (four in the present embodiment) light sources  61   a  through  61   d,  cameras  62   a  and  62   b,  and an analysis portion (not shown). The light sources  61   a  through  61   d  apply light to the object to be sorted conveyed through the sorting region R along the conveyance route C through the transparent walls  21   a  and  21   b.  The light sources  61   a  through  61   d  are arranged such that the light sources  61   a  and  61   b  apply light to the object to be sorted from one side, and that the light sources  61   c  and  61   d  apply light to the object to be sorted from the other side. The light sources  61   a  through  61   d  may be fluorescent lamps, LEDs or the like. 
     Through the transparent wails  21   a  and  21   b,  the cameras  62   a  and  62   b  photograph the object to be sorted to which light is applied so as to produce an image of the object to be sorted. The cameras  62   a  and  62   b  are arranged such that the camera  62   a  photographs the object to be sorted from one side, and that the camera  62   b  photographs the object to be sorted from the other side. While the cameras  62   a  and  62   b  may, for example, be CCD cameras equipped with a line sensor capable of imaging the object to be sorted being conveyed at high speed, this is a mere example and should not be construed restrictively. The analysis portion detects foreign matter F in the object to be sorted based on the image produced by the cameras  62   a  and  62   b.    
     The detection device  6  may further have a background that is used as the background of the object to be sorted when the cameras  62   a  and  62   b  takes a picture of the object to be sorted. 
     The removal device  7  ejects compressed air against the foreign matter F in the sorting region R in order to remove the foreign matter F detected by the detection device  6  into the removal route D. 
     The removal device  7  has an ejector  71  including an ejection port  72 . The ejector  71  is hermetically inserted into the sorting portion  2 , and the ejection port  72  thereof is situated in the sorting region R. When the detection device  6  detects the foreign matter F, the ejector  71  ejects compressed air from the ejection port  72  thereof with a predetermined timing, and applies it to the detected foreign matter F. This causes the object to be sorted to be separated into a product P and the foreign matter F in the sorting region R. As a result, the product P is conveyed along the conveyance route as it is, and the foreign matter F is removed from the conveyance route G, and conveyed along the removal route D. 
     As shown in  FIG. 1B , the sorting portion  2  hermetically surrounds the sorting region R except for the communicating portion C communicating with the first conveying portion  3 , the second conveying portion  4 , and the removing portion  5 . As a result, the region from the air intake port  32  to the first suction device  8  and the second suction device  9  are hermetically surrounded. 
     As shown in  FIG. 1A , the first suction device  8  is provided in the second conveying portion  4 . The first suction device  8  sucks in the air in the conveyance route G, thereby generating an airflow from the air intake port  32  toward the second conveying portion  4  via the sorting region R. As a result, the space from the air intake port  32  to the first suction device  8  is under negative pressure. 
     As shown in  FIG. 2 , the first suction device  8  has a first blower  81 . The first blower  81  has an intake port and an exhaust port. The downstream conveying portions  42   a  and  42   b  are connected to the intake port of the first blower  81 . The product P is introduced through the intake port of the first blower  81 , and is discharged through the exhaust port of the first blower  81 . 
     The second suction device  9  is provided in the removing portion  5 . The second suction device  9  sucks in the air in the removal route D, thereby preventing backflow of the foreign matter F from the removal route D to the sorting region R due to the suction by the first suction device  8 . 
     The second suction device  9  has a second blower  91 . The second blower  91  has an intake port and an exhaust port. The downstream removing portions  52   a  and  52   b  are connected to the intake port of the second blower  91 . The foreign matter F is introduced through the intake port of the second blower  91 , and is discharged through the exhaust port of the second blower  91 . 
     In this color sorting machine M 1 , the first suction device  8  sucks in the air in the conveyance route G from the second conveying portion  4  on the downstream side of the sorting portion  2 , thereby generating an airflow from the first conveying portion  3  past the sorting region R and heading for the second conveying portion  4 . Since the airflow is generated through suction, the airflow is stable while the airflow passes through the sorting region R, that is, when foreign matter F is detected by the detection device  6  and is removed by the removal device  7 . 
     Further, a conveyance route chamber  43  and a removal route chamber  53  are respectively provided in the second conveying portion  4  and the removing portion  5 , whereby variation in the airflow in the conveyance route G and in the removal route D is reduced. As a result, the airflow is further stabilized when passing through the sorting region R. 
     Thus, even if the specific gravity of the object to be sorted is low, the object to be sorted is conveyed by the airflow so as to stably pass through the sorting region R. As a result, the removal device  7  can reliably eject air against the foreign matter F. Thus, even when the object to be sorted consists, for example, foam beads of a very low specific gravity of 0.02 or less, the removal device  7  can properly remove foreign matter F from among the foam beads. 
     Further, the first suction device  8  and the second suction device  9  suck in the air in the conveyance route G and the air in the removal route D, whereby it is possible to respectively place the interior of the conveyance route G and the interior of the removal route D under negative pressure. As a result, it is possible to reduce the air resistance the object to be sorted receives. Thus, the object to be sorted is conveyed more stably passing the sorting region R. 
     Furthermore, the color sorting machine M 1  conveys the object to be sorted by airflow, so that, as compared with the conventional color sorting machine, which conveys the object to be sorted by the gravitational force alone, the speed at which the object to be sorted is conveyed is higher. Thus, the speed at which the object to be sorted is sorted is higher. 
     Further, by conveying the object to be sorted by airflow, it is possible to markedly reduce the remaining amount of the sorted object in the conveyance route G and the removal route D after the sorting of object to be sorted. As a result, the cleaning of the apparatus and the switching of the object to be sorted is facilitated. 
     Second Embodiment 
     Subsequently, the second embodiment of the present invention will be described. 
       FIG. 3  is a schematic sectional view of a color sorting machine M 2  according to the second embodiment of the present invention. The components that are the same as those of the above-described embodiment are indicated by the same reference numerals, and a detailed description thereof will be left out. 
     The supply portion  1  has a vibration feeder  12  instead of the hopper  11 . The vibration feeder  12  vibrates, whereby the object to be sorted flows out of the vibration feeder  12  into the conveyance route G. 
     In the sorting portion  2 , the transparent walls  21   a  and  21   b  are provided so as to be sufficiently spaced away from the conveyance route G. 
     The air intake port  32  is provided at the upstream end of the chute  31 . The object to be sorted flows out of the vibration feeder  12  into the conveyance route G via the air intake port  32 . 
     Instead of the upstream conveying portion  41  and the downstream conveying portions  42   a  and  42   b,  the second conveying portion  4  has a duct-like product conveying portion  44  connected to the sorting portion  2  and the first suction device  8 . 
     Instead of the upstream removing portion  51  and the downstream removing portions  52   a  and  52   b,  the removing portion  5  has a duct-like foreign matter conveying portion  54  connected to the sorting portion  2  and the second suction device  9 . 
     The ejector  71  is provided in the sorting region R so as to be spaced away from the conveyance route G so that the ejector  71  may not hinder the conveyance of the object to be sorted. 
     The first suction device  8  further has a sorted object cyclone  82 . The sorted object cyclone  82  separates the sorted object conveyed via the second conveying portion  4 , that is, the product P, from a gas. The sorted object cyclone  82  is formed in a funnel-like tapering downward. The sorted object cyclone  82  has on the upper side thereof an exhaust port  821  connected to the intake port of the first blower  81 . The sorted object cyclone  82  further has a product introducing port  822  provided below the exhaust port  821 , and a product discharging port  823  provided at the lower end. 
     The product P is introduced into the sorted object cyclone  82  along with a gas through the product introducing port  822  by the airflow generated by the first blower  81 . The introduced product P is attracted downwards by the gravitational force. On the other hand, the gas is sucked through the exhaust port  821  on the upper side of the sorted object cyclone  82 . As a result, the product P is separated from the gas, and is discharged through the product discharging port  823  without being introduced into the first blower  81 . 
     The second suction device  9  further has a foreign matter cyclone  92 . The foreign matter cyclone  92  is formed in a funnel-like tapering downward. The foreign matter cyclone  92  has on the upper side thereof an exhaust port  921  connected to the intake port of the second blower  91 . The foreign matter cyclone  92  further has a foreign matter introducing port  922  provided below the exhaust port  921 , and a foreign matter discharging port  923  provided at the lower end. 
     The foreign matter cyclone  92  separates the foreign matter F from the gas by the same method as that of the sorted object cyclone  82 . That is, the foreign matter F is introduced into the foreign matter cyclone  92  from the foreign matter introducing port  922  along with the gas by the airflow generated by the second blower  91 . The introduced foreign mater F is attracted downwards by the gravitational force. On the other hand, the gas is sucked through the exhaust port  921 . As a result, the foreign matter F is separated from the gas, and is discharged through the foreign matter discharging port  923  without being introduced into the second blower  91 . 
     As in the color sorting machine M 1 , in this color sorting machine M 2  also, it is possible to properly remove foreign matter F in the object to be sorted. 
     When, for example, the object to be sorted is a pulverized object such as flour, and when the object to be sorted adheres to the transparent walls  21   a  and  21   b,  the detection device  6  cannot detect foreign matter F in the object to be sorted. In this connection, in the color sorting machine M 2 , the transparent walls  21   a  and  21   b  are sufficiently spaced away from the conveyance route G, whereby adhesion of the object to be sorted to the transparent walls  21   a  and  21   b  is suppressed. Further, due to the provision of the sorted object cyclone  82  and the foreign matter cyclone  92 , when the object to be sorted is a pulverized object, the product P and the foreign matter F are easily separated from the gas. Thus, the color sorting machine M 2  is suitable for sorting an object to be sorted in the form of a pulverized object. 
     Third Embodiment 
     Subsequently, the third embodiment of the present invention will be described. 
       FIG. 4A  is a schematic sectional view of a color sorting machine M 3  according to the third embodiment of the present invention. The components that are the same as those of the above-described embodiments are indicated by the same reference numerals, and a detailed description thereof will be left out. 
     As shown in  FIGS. 4A and 4B , instead of the removal device  7 , the color sorting machine M 3  is equipped with a route switching device  10 . When no foreign matter F is detected, the route switching device  10  establishes communication between the sorting portion  2  and the second conveying portion  4 , and prohibits communication between the sorting portion  2  and the removing portion  5 . When some foreign matter F is detected, the route switching device  10  prohibits communication between the sorting portion  2  and the second conveying portion  4 , and establishes communication between the sorting portion  2  and the removing portion  5 . 
     The route switching device  10  has a valve body  101  and a valve shaft  102 . The valve shaft  102  is rotatably provided at the portion where the upstream conveying portion  41  and the upstream removing portion  51  branch off from the sorting portion  2 . The valve body  101  is supported by the valve shaft  102 , and, through rotation of the valve shaft  102 , the valve body  101  can move between a first position indicated by the solid line and a second position indicated by the phantom line. 
     The color sorting machine M 3  sucks in the air in the removal route D by the second suction device  9 , thereby generating an airflow heading for the removing portion  5  from the sorting region R. 
     Next, to be described will be a method by which when the color sorting machine M 3  detects foreign matter F, the foreign matter F is removed into the removal route D. 
     When no foreign matter F is detected, the valve body  101  is at the first position, with the sorting portion  2  and the second conveying portion  4  communicating with each other, and the sorting portion  2  and the removing portion  5  not communicating with each other. As a result, in the color sorting machine M 3 , it is possible to convey the product P along the conveyance route G by the airflow generated by the first suction device  8 . 
     When some foreign matter F is detected, the valve body  101  moves from the first position to the second position with a predetermined timing, and communication between the sorting portion  2  and the second conveying portion  4  is prohibited, with communication between the sorting portion  2  and the removing portion  5  being allowed. That is, the conveyance route G is cut off by the valve body  101 , and the removal route D is opened to the sorting region R. As a result, the color sorting machine M 3  can remove the detected foreign matter F into the removal route D from the conveyance route G by the airflow generated by the second suction device  9 . After a predetermined period of time has elapsed, the valve body  101  is returned from the second position to the first position. 
     The above structure of the route switching device  10  is only given by way of example, and should not be construed restrictively. In another possible structure of the route switching device  10 , for example, each of the communicating portion between the sorting portion  2  and the second conveying portion  4  and the communicating portion between the sorting portion  2  and the removing portion  5  is provided with a pair of valve shaft and valve body. 
     As in the color sorting machines M 1  and M 2 , also in this color sorting machine M 3 , the airflow passing through the sorting region R is stable, and the speed at which the object to be sorted is conveyed is stable. Thus, the color sorting machine M 3  can properly remove the detected foreign matter F by the route switching device  10 . 
     The present invention is not restricted to the above-described embodiments but allows modifications as appropriate. For example, the following modifications may be applied to the above-described embodiments, or the above-described embodiments may be combined with the following modifications. 
     (i) The air intake port  32  may be provided in the supply portion  1 . In this case, it is desirable for the first conveying portion  3  to be hermetically connected to the supply portion  1  and the sorting portion  2  and to hermetically surround the conveyance route G to the sorting portion  2 . 
     (ii) The color sorting machines M 1  through M 3  may be further equipped with an opening adjustment portion adjusting the amount of air taken in through the air intake port  32 . The opening adjustment portion can adjust the speed of the airflow generated by the first suction device  8  as appropriate by adjusting the air intake amount. Thus, in the case, for example, where the mixing rate of foreign matter F in the object to be sorted is high, the color sorting machines M 1  through M 3  adjust the speed of the airflow to reduce the conveying speed of the object to be sorted, thereby enhancing the sorting accuracy. 
     (iii) The color sorting machines M 1  through M 3  may be equipped with a filter for removing dust, in the conveyance route G and the removal route D. 
     DESCRIPTION OF THE REFERENCE CHARACTERS 
     
         
           1  supply portion 
           11  hopper 
           12  vibration feeder 
           2  sorting portion 
           21   a,    21   b  transparent wall 
           22  opaque 
           3  first conveying portion 
           31  chute 
           32  air intake port 
           4  second conveying portion 
           41  upstream conveying portion 
           42   a,    42   b  downstream conveying portion 
           43  conveyance route chamber 
           44  product conveying portion 
           5  removing portion 
           51  upstream removing portion 
           52   a,    52   b  downstream removing portion 
           53  removal route chamber 
           54  foreign matter removing portion 
           6  detection device 
           61   a  through  61   d  light source 
           62   a,    62   b  camera 
           7  removal device 
           71  ejector 
           72  ejection port 
           8  first suction device 
           81  first blower 
           82  sorted object cyclone 
           821  exhaust port (sorted object cyclone) 
           822  product introducing port 
           823  product discharging port 
           9  second suction device 
           91  second blower 
           92  foreign matter cyclone 
           921  exhaust port (foreign matter cyclone) 
           922  foreign matter introducing port 
           923  foreign matter discharging port 
           10  route switching device 
           101  valve body 
           102  valve shaft 
           100  conventional supply device 
           200  object to be sorted in the conventional supply device 
           300  detection device in the conventional sorting device 
           400  compressed air supply portion of the conventional supply device 
           500  air ejection port of the conventional supply device 
           600  air ejecting portion of the conventional supply device 
           700  line groove of the conventional supply device 
           800   a,    800   b  transparent wall of the conventional supply device 
           900  ejection nozzle of the conventional sorting device 
         M 1 , M 2 , M 3  color sorting machine 
         G conveyance route 
         D removal route 
         R sorting region 
         P product 
         F foreign matter 
         C communicating portion