Patent Publication Number: US-2009236150-A1

Title: Weighing device

Description:
This national phase application claims priority to Japanese Patent Application No. 2006-138870 filed on May 18, 2006. The entire disclosure of Japanese Patent Application No. 2006-138870 is hereby incorporated herein by reference 
     TECHNICAL FIELD  
     The present invention relates to a weighing device which weighs objects while conveying the objects, sorts the objects to predetermined places, and discharges the objects. 
     BACKGROUND ART  
     The work of boxing a large number of objects carried by a conveyer or the like so that a predetermined target weight is maintained lacks efficiency when the work depends on manpower. Particularly, when the objects are natural objects with different weights, the work becomes more inefficient. 
     In view of this, a weighing device has been proposed which measures the weight of each of the objects carried in by a carry-in conveyer by using a weighing unit that is successively provided on a weighing conveyer while conveying the objects, sorts and discharges the objects to a plurality of predetermined places (places where storage boxes of the objects are set), integrates the weights in each of the predetermined places, and sets the drop weights of the objects to each of the predetermined places to the target weight or more (see Japanese Laid-Open Patent Application Publication No. 5-57253). 
     DISCLOSURE OF THE INVENTION 
     According to the above mentioned reference, the integration weight of the objects actually sorted may be widely different from the target total weight of the objects sorted to one of the predetermined discharge places. For example, when discharging natural objects such as lettuce or cabbage so that the target total weight of 5,000 g in each of the discharge places is secured, the actual integration weight is less than the target total weight if the actual integration weight is 4,850 g. In such a case, even when the individual weight of an object carried next is as heavy as approximately 500 g, the object must be dropped to be added to the integration weight. 
     However, the actual integration weight then becomes approximately 5,350 g, which exceeds the target total weight by approximately 350 g, resulting in a degraded yield. In the case of an average excess weight of 200 g per a predetermined discharge place when there are 20 predetermined discharge places set on one sorting conveyer, the resulting yield degradation is 4,000 g. 
     Such a rise in cost caused by the yield degradation is a burden for producers, consumers, or the like, and therefore there was a need for improvement of the weighing device. 
     The present invention provides a weighing device capable of improving the yield when quantitatively weighing objects having unfixed individual weights such as natural objects. 
     A first aspect of the present invention provides a weighing device including a weighing unit, a conveying unit, a plurality of discharge parts, a discharging unit and a controlling part. The weighing unit is configured and arranged to measure weights of objects. The conveying unit is configured to convey the objects weighed by the weighing unit. The objects conveyed by the conveying unit are discharged to the discharge parts. The discharging unit is configured and arranged to discharge the objects to the discharge parts. The controlling part is configured to set an order of priority for the discharge parts, to sort the objects weighed by the weighing unit into a plurality of predetermined weight ranks, to select a combination of a plurality of the objects in the same weight rank so that the combination has a total weight equal to a final target weight, and to control the discharging unit to discharge the objects selected for the combination into one of the discharge parts having the highest priority among the discharge parts that are not being used. 
     A second aspect of the present invention provides a weighing device as set forth in the first aspect, wherein the weighing unit is configured to use a total weight of at least two objects continuously disposed on a conveying path of the conveying unit as a measured weight of the objects. 
     With the weighing device according to the first aspect, whenever the objects are newly combined and selected regardless of the sorted weight rank, a discharge part which is not used is selected from the plurality of discharge parts, and the objects are discharged into the discharge part. Therefore, since the discharge of the objects newly combined and selected can be started without having to wait until all the objects previously combined and selected in the same weight rank are discharged, the discharge cycle can be speeded up to enhance the processing efficiency. In addition, since the discharge parts are not set corresponding to each of the weight ranks, it is possible to do with a smaller number of discharge parts, thereby minimizing the installation space and cost. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         FIG. 1  is a functional block diagram showing a weighing device according to a first embodiment of the present invention; 
         FIG. 2  is a flowchart showing of the control executed in the weighing device according to the first embodiment of the present invention; 
         FIG. 3  is a schematic view of the weighing device according to the first embodiment of the present invention; 
         FIG. 4  is a schematic view showing processing in the weighing device according to the first embodiment of the present invention; 
         FIG. 5  is a front view of a weighing device according to a second embodiment of the present invention; 
         FIG. 6  is a right side view of the weighing device according to the second embodiment of the present invention; and 
         FIG. 7  shows the content of weight ranks of objects (e.g., salmon) sorted in the second embodiment of the present invention. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     First Embodiment  
     The first embodiment of the present invention relates to a weighing device which is used for shipping natural objects (hereinafter, referred to as “objects P”) such as lettuces, the weights of the lettuces being unequal, and combines and discharges a plurality of objects P so that the total weight of the objects P reaches a final target weight set as a shipping boxed weight. The weighing device discharges (drops) the combinations into a plurality of different discharge parts in a simultaneous, parallel manner. 
       FIG. 1  is a functional block diagram showing a weighing device  1  according to a first embodiment of the present invention.  FIG. 2  is a flowchart showing the procedure of the weighing device  1  according to the first embodiment of the present invention.  FIG. 3  is a schematic view of the weighing device  1 .  FIG. 4  is a concept view showing processing in the weighing device  1 . 
     In  FIG. 3 , reference numeral  10  designates a carry-in conveyer, reference numeral  11  designates a weighing conveyer, reference numeral  12  designates a conveyance conveyor, reference numeral  13  designates a weighing unit, reference numeral  14  designates a controlling part, reference numeral  15  designates a plurality of discharging units, and reference character D m (D 1 -D M ) designates a plurality of discharge parts. The discharge part D m  is represented by a box shape in  FIG. 3 . However, the discharge part D m  is intended as a broad concept encompassing not only a box, a container, and the like for storing the objects P but also a mere dropping port, a dropping place, or the like for storing the objects P. 
     Overall Structure of Weighing Device  1   
     In  FIG. 3 , the carry-in conveyer  10  carries the objects P into the weighing conveyer  11  sequentially. The weighing unit  13  is successively provided on the weighing conveyer  11 . The weighing unit  13  individually measures the weights of the objects P carried in from the carry-in conveyer  10 , and outputs the measurement results to the controlling part  14 . 
     The conveyance conveyor  12  conveys the objects P conveyed from the weighing conveyer  11  to the plurality of discharge parts D 1  to D M  provided along a conveying path. 
     The discharging units  15  are provided opposite to the discharge parts D m  so as to sandwich the conveyance conveyor  12  between the plurality of discharge parts D 1  to D M . The discharging units  15  discharge, that is, drops the objects P conveyed on the conveying path of the conveyance conveyor  12  into a corresponding discharge part D m  according to a signal from a discharging control section  145 , described later. 
     Controlling Part  14   
     As shown in  FIG. 1 , the controlling part  14  is composed of an integrating section  141 , a storing section  142 , a calculating section  143 , a comparing section  144 , the discharging control section  145 , and a weight setting section  146 , and generally controls the functions of the constituent sections. The functions of these constituent sections are as follows. 
     The weight setting section  146  has a function for setting a final target weight T N  of the plurality of objects dropped into each of the discharge parts D m  (one discharge part) from the numeric keypad or the like which is not shown, and also has, as necessary, a function for setting an intermediate target weight T n+1  which is a target weight in each of dropping times. 
     The final target weight T N  is a target value of the total dropping weight of the objects P dropped N times one by one into each of the discharge parts D m . The intermediate target weight T n+1  is a target value of the total dropping weight of the objects P to each of the discharge parts D m  in each of the dropping times of the second dropping to the (N−1)th dropping. The intermediate target weight T n+1  is set in a fixed manner by the weight setting section  146 . In addition, the intermediate target weight T n+1  is calculated based on the average unit weight obtained by dividing the total dropping weight of the objects P in the previous dropping time (n-th dropping) or the total dropping weight of the objects P leading up to the previous dropping time (n-th dropping) by the number of corresponding dropped objects. The intermediate target weight T n+1  is set for averaging the total dropping weight of each of the discharge parts D m  in each of dropping times. The average unit weight is obtained by totalizing integration weights S mn  (described later) of all the objects P dropped into M discharge parts D m  and dividing the total by the number M of the discharge parts and the dropping number n. 
     The integrating section  141  has a function for calculating the integration weight S mn  leading up to the n-th dropping to each of the discharge parts D m  in each of dropping times of the first dropping to the N-th dropping (the final dropping). 
     The calculating section  143  has a function for calculating an intermediate target weight difference T n+1 −S mn , in each of dropping times. The intermediate target weight difference T n+1 −S mn  is a difference between the intermediate target weight T n+1  calculated based on the average unit weight of the objects P obtained from the dropping weight leading up to the previous dropping time (n-th dropping) or the previous dropping time or the intermediate target weight T n+1  set in a fixed manner by the weight setting section  146  and the integration weight S mn  leading up to the n-th dropping in each of the discharge parts D m . Also, the calculating section  143  has a function for calculating a final target weight difference T N −S mn  in each of dropping times. The final target weight difference T N −S mn  is a difference between the final target weight T N  set by the weight setting section  146  and the integration weight S mn  leading up to the n-th dropping in each of the discharge parts D m . 
     The storing section  142  is provided with three storing section  142   a,    142   b,    142   c.  The storing section  142   a  stores the integration weight S mn  of each of the discharge parts D m . The storing section  142   b  stores the intermediate target weight T n+1  and the final target weight T N . The storing section  142   c  has a function for storing the intermediate target weight difference T n+1 −S mn  of each of the discharge parts D m  and the final target weight difference T N −S mn . 
     The comparing section  144  has a function for mutually comparing a difference between the intermediate target weight difference T n+1 −S mn  of each of the discharge parts D m  and the weights of the objects P newly carried in, and a function for mutually comparing a difference between the final target weight difference T N −S mn  of each of the discharge parts D m  and the weights of the objects P newly carried in. The comparison result obtained by the comparing section  144  is transmitted to the discharging control section  145 . 
     The discharging control section  145  has a function for recognizing, from the discharge part D 1  to D M , a discharge part D m  having an intermediate target weight difference T n+1 −S mn  closest to the individual weights of the objects P newly carried in based on the comparison result obtained by the comparing section  144  until the (N−1)th dropping (before the final dropping) and for transmitting a signal for dropping the objects P into the discharging unit  15  that corresponds to the discharge part D m . Also, in the N-th dropping time (the final dropping), the discharging control section  145  has a function for recognizing, from the discharge parts D 1  to D M , a discharge part D m  in which the individual weights of the objects P newly carried in are no less than the final target weight difference T N −S mn  and are closest to the final target weight difference T N −S mn  based on the comparison result and for transmitting a signal for dropping the objects P into the discharging unit  15  that corresponds to the discharge part D m . 
     Discharge Control  
     Hereinafter, the specific structure of discharge control obtained by the weighing device  1  according to this embodiment will be described. 
     First Dropping  
     The discharge control of the first dropping will be described based on  FIGS. 1 to 3 . First, as shown in  FIG. 3 , objects P to be dropped first time are sequentially carried in from the carry-in conveyer  10 , and the objects P are individually weighed by the weighing unit  13  successively provided on the weighing conveyer  11  (S 101 ). As shown in  FIG. 3 , each of the objects P is dropped into each of the discharge parts D m  by the discharging unit  15  from the conveying path of the conveyance conveyor  12  (S 102 ). In that case, the measured weight of each of the objects P is stored in a predetermined storing area in the storing section  142   a  as the integration weight S m1  of each of the discharge parts D m  (S 103 ). 
     When the dropping of the objects P to all the discharge parts D 1  to D M  is confirmed (S 104 ), the average unit weight of the first dropping in each of the discharge parts D m  is calculated by the calculating section  143  (S 105 ). This average unit weight is obtained by dividing the added value (S 11 +S 21 + . . . +S m1 + . . . +S M1 ) of the integration weight S m1  of each of the discharge parts D m  by the number M of the discharge parts and dropping time 1(n). Next, a value obtained by doubling ((n+1) times) the above average unit weight is calculated as an intermediate target weight T 2 (T n+1 ) of the second dropping ((n+1)th dropping) (S 106 ), and is stored in the predetermined storing area in the storing section  142   b.    
     Also, an intermediate target weight difference T 2 −S m1  (T n+1 −S mn ) in the second dropping, which is calculated in each of the discharge parts D m  by the calculating section  143  (S 106 ), is stored in the predetermined storing area of the storing section  142   c.  This intermediate target weight difference T 2 −S m1  is calculated by subtracting the measured weight (integration weight S m1 ) of the first dropping in each of the discharge parts D m  from the intermediate target weight T 2 . 
     The discharge control of the first dropping will be described based on specific numerical values shown in  FIG. 4 . Herein, six discharge parts D 1  to D 6  are provided, and the final target weight T N  common to the discharge parts is set to 5,000 g. As shown in  FIG. 4 , when the weights of the objects P discharged to each of the discharge parts in the first dropping are 550 g, 600 g, 500 g, 400 g, 450 g, and 560 g, then the calculating section  143  calculates the average unit weight 510 g (=(550 g+600 g+500 g+400 g+450 g+560 g)/6) of the discharge parts D 1  to D 6 . Further, the calculating section  143  calculates the intermediate target weight T 2  (1,020 g=510 g times 2) of the second dropping. The intermediate target weight T 2  is stored in the predetermined storing area in the storing section  142   b.    
     Next, the intermediate target weight difference of the second dropping in each of the discharge parts is calculated as a difference T 2 −S m1  between the intermediate target weight T 2  (1,020 g) and the integration weight S m1  (550 g, 600 g, 500 g, 400 g, 450 g, 560 g) in the first dropping of each of the discharge parts. That is, in the discharge part D 1 , the intermediate target weight difference is calculated as 1,020 g−550 g=470 g. The intermediate target weight differences in the discharge parts D 2  to D 6  are also similarly calculated as 420 g, 520 g, 620 g, 570 g, and 460 g. The intermediate target weight differences T 2 −S m1  are stored in the predetermined storing area in the storing section  142   c.    
     Second Dropping  
     Next, the discharge control of the second dropping will be described based on  FIGS. 1 to 3 . First, as shown in  FIG. 3 , the objects P dropped second time from the carry-in conveyer  10  are sequentially carried in, and the objects P are individually weighed by the weighing unit  13  successively provided on the weighing conveyer  11  (S 107 ). The measurement data is transmitted to the comparing section  144 . The comparing section  144  reads the intermediate target weight difference T 2 −S m1  of the second dropping of each of the discharge parts D m  from the storing section  142   c,  and compares the read intermediate target weight difference T 2 −S m1  with the weights of the individually weighed objects P. The comparison result is transmitted to the discharging control section  145 . The discharging control section  145  sends a signal to the discharging unit  15  corresponding to the discharge part D m  so as to drop the objects P into a discharge part D m  having an intermediate target weight difference T 2 −S m1  closest to the measured weights of the objects P based on the comparison result. The discharging unit  15 , which receives the signal, drops the objects P into the discharge part D m  (S 108 ). 
     The measured weights of the objects P are integrated to the integration weight S m1  of the first dropping of the discharge part D m  into which the objects P are dropped (S 109 ). The new integration weight S m2  obtained by this integration is stored in the predetermined storing area in the storing section  142   a.    
     When the second object dropping to all the discharge parts D 1  to D 6  is confirmed (S 110 ), the average unit weight of the second dropping is calculated by the calculating section  143  (S 111 ). The average unit weight is obtained by (S 12 +S 22 + . . . +S m2 + . . . +S M2 )/(M×2). Herein, “2” used for the division is the dropping number. Next, a value obtained by tripling the average unit weight is calculated as an intermediate target weight T 3  (T n+1 ) to the third dropping ((n+1)th dropping) (S 112 ). The value is stored in the predetermined storing area in the storing section  142   b.    
     An intermediate target weight difference T 3 −S m2  (T n+1 −S mn ) in the third dropping is calculated in each of the discharge parts D m  by the calculating section  143 , and stored in the predetermined storing area in the storing section  142   c.  The intermediate target weight difference T 3 −S m2  of each of the discharge parts D m  is obtained by subtracting the integration weight S m2  after the second dropping end in each of the discharge parts D m  from the intermediate target weight T 3  common to all the discharge parts D m . 
     The discharge control of the second dropping will be described based on the specific numerical values shown in  FIG. 4 . For example, when the individual weight of the object P carried in first in the second dropping is 425 g, the individual weight of 425 g is compared with the intermediate target weight difference T 2 −S m  (470 g, 420 g, 520 g, 620 g, 570 g and 460 g) of the second dropping shown in  FIG. 4 . Based on the comparison result indicating that the 425 g individual weight is closest to the 420 g intermediate target weight difference of the discharge part D 2 , the object P is dropped into the discharge part D 2  by the discharging control section  145 . 
     The other objects P in the second dropping are also subjected to the same processing. The dropping of the objects P to all the discharge parts D 1  to D 6  is confirmed (S 110 ), the discharge processing of the second dropping is completed, and the average unit weight is calculated by the calculating section  143 . 
     The processing of S 107  to S 112  described above is succeedingly repeated up to the third dropping, the fourth dropping . . . the (N−1)th dropping. After the dropping of the objects P to all the discharge parts D 1  to D 6  is confirmed up to the (N−1)th dropping after the second dropping (S 110 ), it is determined whether or not the next dropping is the N-th time (the final dropping) (S 113 ). 
     Processing for Determining Final Dropping  
     It is determined whether or not the next dropping is the final dropping (N-th dropping) by comparing a total value α (hereinafter, merely referred to as α) of the final target weight differences T N −S mn  with a total value β (hereinafter, simply referred to as β) of the average dropping weights obtained by dividing the integration weight S mn  up to the previous dropping time by the dropping number n. Specifically, it is determined whether or not the next dropping is the final dropping according to whether or not α is contained in the weight range of ±20% of β. 
     Specifically, the calculating section  143  calculates the final target weight difference T N −S mn  in addition to the intermediate target weight difference T n+1 −S mn , and calculates the total value of the final target weight differences T N −S mn  of all the discharge parts as α. 
     Also, the calculating section  143  calculates an average dropping weight S mn /n obtained by dividing the integration weight S mn  by the dropping number n for each of the discharge parts, and calculates the total value of the average dropping weights S mn /n of all the discharge parts as β. The calculated total values α and β are stored in the predetermined storing area in the storing section  142   a.    
     It is confirmed whether or not the M objects P are dropped in each of the dropping times (S 110 ), and the target weight of the next dropping is calculated (S 111 , S 112 ). Then, the calculating section  143  determines whether no not a is contained in the weight range of ±20% of β (S 113 ). 
     When α is not contained in the weight range of ±20% of β, it is determined that the next dropping is not yet the final dropping (N-th dropping). The object P discharged next time is discharged to a discharge part D m  having an intermediate target weight difference closest to the measured weight of the object P. On the other hand, when α is contained in the weight range of ±20% of β, it is determined that the next dropping is the final dropping, and the discharge control peculiar to the final dropping to be described later is carried out. 
     The processing for judging whether or not the next dropping is the final dropping will be described based on the specific numerical values shown in  FIG. 4 . As shown in  FIG. 4 , when the integration weights S 1(N−1)  to S 6(N−1)  of the discharge parts D 1  to D 6  up to the (N−1)th dropping are 4,700 g, 4,550 g, 4,600 g, 4,400 g, 4,450 g, and 4,500 g, then the final target weight differences T N −S m(N−1)  of the discharge parts D 1  to D 6  are 300 g, 450 g, 400 g, 600 g, 550 g, and 500 g, and the final target weight differences T N −S m(N−1)  are obtained by subtracting the integration weight from the final target weight of 5,000 g. The total value α of these is 2,800 g. 
     Also, as shown in  FIG. 4 , when the (N−1)th dropping is the 9th time, the integration weights of the discharge parts D 1  to D 6  are 4,700 g, 4,550 g, 4,600 g, 4,400 g, 4,450 g, and 4,500 g, and thereby the average unit weights of these are 4,700/9 g, 4,550/9 g, 4,600/9 g, 4,400/9 g, 4,450/9 g, and 4,500/9 g. The total value β of these is calculated to be approximately 3,022 g. 
     Furthermore, the calculating section  143  calculates the weight range (2,418 g to 3,628 g) which is ±20% based on the total value β (3,022 g). The comparing section  144  compares and determines whether or not the total value α (2,800 g) is included in the weight range (2,418 g to 3,628 g) (S 113 ). Herein, since 2,800 g (β) is more than 2,418 g and less than 3,628 g, the total value α is determined to be in the weight range, and it is recognized that the next dropping is the final dropping. 
     Final Dropping  
     The discharge control of the final dropping will be described. The discharge control of the final dropping (N-th dropping) discharges the objects P to a discharge part D m  having such a relationship that the measured weights of the objects P carried in are closest to the difference (final target weight difference T N −S m(N−1) ) between the final target weight T N  and the integration weight S m(N−1)  up to the (N−1)th dropping and no less than the final target weight difference T N −S m(N−1) . 
     The discharge control of the final dropping will be described based on the specific numerical values shown in  FIG. 4 . As shown in  FIG. 4 , the final target weight differences T 10 −S m9  (T N −S m(N−1) ) of the discharge parts D 1  to D 6  are 300 g, 450 g, 400 g, 600 g, 550 g, and 500 g. If the objects which are no less than these weight differences are dropped, the final target weight of 5,000 g is reached. 
     The objects P of the tenth dropping (N-th dropping) are newly carried in from the carry-in conveyer  10 . The objects P are individually weighed by the weighing unit  13  successively provided on the weighing conveyer  11  (S 114 ). The measured weights are transmitted to the comparing section  144 . The comparing section  144  reads the final target weight differences T 10 −S m9  of the discharge parts D 1  to D 6  stored in the storing section  142   c,  compares the final target weight difference with the measured weight for each of the discharge parts, and transmits the comparison result and the final target weight difference of each of the discharge parts to the discharging control section  145  ( FIG. 1 ). 
     For example, when the measured weight of the objects P carried in from the carry-in conveyer  10  is 575 g, the comparing section  144  determines that the difference between the final target weight difference (600 g) of D 4  and the measured weight, and the difference between the final target weight differences (550 g) of D 5  and the measured weight are 25 g, and the weights of discharge parts D 4  and D 5  are the closest to the measured weight (575 g). The comparing section  144  transmits the comparison result and the final target weight differences according to the discharge parts D 4 , D 5  to the discharging control section  145 . 
     The discharging control section  145  receives the comparison result and determines a discharge part D m  which is closest to the measured weight based on the comparison result and has the final target weight difference T 10 −S m9  being no less than the measured weight. The discharging control section  145  discharges the objects P to the discharge part. Herein, since the weight (575 g) of the objects P newly carried-in is no less than the final target weight difference (550 g) of D 5 , the discharging control section  145  transmits a signal to the discharging unit  15  that corresponds to the discharge part D 5 , and the discharging unit  15  discharges the objects to the discharge part D 5  (S 115 ). 
     The weights of the dropping objects are integrated in each of the discharge part, and the final integration weights are respectively calculated (S 116 ). 
     Hereinafter, the same processing is repeated, and when it is confirmed that the objects are dropped into all the discharge parts D 1  to D 6  (S 117 ), a series of discharge processing is completed. 
     Features of Weighing Device  1  According to First Embodiment  
     The weighing device  1  according to the above first embodiment is characterized by being provided with the controlling part  14 . The controlling part  14  includes the weight setting section  146 , the integrating section  141 , the calculating section  143 , the storing section  142 , the comparing section  144 , and the discharging control section  145 . The weight setting section  146  sets the final target weight T N  of the plurality of objects P discharged to the discharge part D m . The integrating section  141  integrates the measured weights measured by the weighing unit  11  in each of the discharge parts D m . The calculating section  143  calculates the final target weight difference T N −S mn  in each of the discharge parts D m , which is a difference between the integration weight S mn  integrated by the integrating section  141  and the final target weight T N . The storing section  142  stores the final target weight T N , the integration weight S mn , and the final target weight difference T N −S mn . The comparing section  144  compares the weights of the objects P measured by the weighing unit  11  with the final target weight difference T N −S mn . The discharging control section  145  discharges the weighed objects to a discharge part D m  having a final target weight difference T N −S mn  closest to the measured weights based on the comparison result. This prevents a situation where the discharge weight total serving as the shipped product weight exceeds the final target weight T N  to a large extent, and as a result, the yield can be improved for producers. Also, since the shipped product weight is naturally concentrated near the final target weight T N , weight variation among the products (box) is suppressed, and the product quality can be enhanced for consumers. 
     The weighing device I according to the above first embodiment is characterized in that the discharging control section  145  discharges the weighed objects to a discharge part D m  in which the measured weights of the objects is no less than the final target weight difference T N −S mn . This prevents a situation where the shipped product weight is less than a shipping boxed weight (final target weight T N ), and as a result, the generation of dissatisfaction of the consumers can be certainly prevented. 
     The weighing device  1  according to the above first embodiment is characterized in that the calculating section  143  calculates the intermediate target weight difference T n+1 −S mn , which is the difference between the intermediate target weight T n+1  and the integration weight S mn  in each of dropping times of the objects P; the storing section  142  stores the intermediate target weight T n+1  and the intermediate target weight difference T n+1 −S mn ; and the discharging control section  145  discharges the weighed objects to a discharge part having a intermediate target weight difference T n+1 −S mn  closest to the measured weights of the objects. Therefore, the discharge weights of the objects P discharged to the discharge parts D m  are adjusted while being divided into a plurality of times in each of dropping times to attain further improvement of the yield and enhanced quality caused by equalization of the product weights. 
     The weighing device  1  according to the above first embodiment is characterized in that the intermediate target weight T n+1  is calculated based on the average unit weight of the objects P discharged to each of the discharge parts D m . Therefore, the intermediate target weight T n+1  is calculated in each of dropping times based on the actual object discharge weight, and as a result, the yield can be further improved for the producers. Also, the weight variation between the products (boxes) is suppressed, and the shipped product weight can be equalized to further enhance the product quality for the product consumers. 
     Modifications of First Embodiment  
     (1) In the above first embodiment, the discharge control based on the intermediate target weight difference is carried out in each of the dropping times of the second dropping time to the (N−1)th dropping time. However, the present invention is not limited thereto. The carried-in objects P may be sequentially dropped into the discharge parts D m  regardless of the measured weights of the objects up to the second dropping time to the (N−1)th dropping time to carry out only the processing for judging whether or not the dropping time is the final dropping. When the dropping time is determined as the final dropping, the discharge control based on the final target weight difference described above is carried out. This modification can also attain an improvement in the yield and the enhanced quality of the shipped products caused by the equalization of the object weights as in the above first embodiment. 
     (2) In the above first embodiment, the intermediate target weight is calculated based on the average individual weight of the objects P previously dropped. However, the present invention is not limited thereto. The individual weights of the objects P are set in advance in a fixed manner, and the intermediate target weight may be calculated based on the individual weights. For example, in the above first embodiment, the individual weight used in order to calculate the intermediate target weight is fixed to 500 g, and the discharge control may be carried out with the intermediate target weight of the second dropping time being set to 1,000 g and the intermediate target weight of the third dropping time being set to 1,500 g . . . . This modification also exhibits the same effect as that of the above embodiment. 
     (3) In the above first embodiment and the above modification (1), the judgment as to whether or not the next dropping is the final dropping is carried out according to whether or not the total α of the final target weight differences of the discharge parts D 1  to D M  is contained in the weight range of ±20% of the dropping time average β of the integration weight in the discharge parts D 1  to D M  up to the (N−1)th dropping time. However, the present invention is not limited thereto. The number of the objects P dropped into one discharge part may be fixed in advance. When the dropping number is subtracted one by one from the above scheduled dropping number on every dropping time to reach 0 (zero), or when the dropping number is integrated one by one from 0 on every dropping time and the integrated number reaches the above scheduled dropping number, it may be determined that the next dropping is the final dropping. This modification also exhibits the same effect as that of the above first embodiment or the like. 
     (4) In the above first embodiment and the above modifications (1) to (3), each of the objects P individually weighed by the weighing unit  13  is discharged to each of the discharge parts D m , and the individual weight data thereof are integrated one by one by the integrating section  141 . However, the present invention is not limited thereto. The selection and integration of weight of the objects P discharged to one discharge part may be carried out not one by one but collectively for the plurality of objects. For example, the weight data of the plurality of objects on the conveying path of a conveying unit  12  may be added up, and the added-up weight data may be treated as one data. The plurality of objects may be discharged to one discharge part D m , and the added-up data may be integrated by the integrating section  141 . Particularly, when the objects collectively selected are continuous on the conveying path, the speed-up of the discharge processing can be attained. Further, when the conveying unit  12  is a system circulating and conveying the objects, the holding time of the objects on the conveying path can be shortened. 
     (5) In the above first embodiment and the above modifications (1) to (4), the number of the objects discharged in each of the dropping times is fixed. However, the number of the discharged objects may be changed according to the dropping number. For example, one object is discharged to one discharge part for one dropping time until a predetermined dropping time or a predetermined weight is reached. When the predetermined dropping time or the predetermined weight is reached, the plurality of objects having the same weight (including the weight in an allowable range) as the final target weight difference to one discharge part may be combined and selected, and the plurality of objects may be discharged collectively or separately. Herein, the plurality of objects combined and selected include an object continuously conveyed on the conveying path and an object conveyed in a discontinuous state where the object discharged to another discharge part D m  is interposed on the conveying path. 
     (6) In the above first embodiment and the above modifications (1) to (5), the objects P are conveyed one by one on the conveying path of the conveyance conveyor  12 . However, the present invention is not limited thereto. The plurality of objects may be stored in a container such as a packet, and be conveyed. The plurality of objects may be collectively discharged to one discharge part by the discharging unit. Also, the plurality of objects may be individually weighed by the weighing unit  13 , and the objects may be then collectively stored in the container. In addition, the objects may be also collectively weighed with the objects stored in the container. The number of the objects stored in one container is not limited to plural number, and may be one, as a matter of course. 
     Second Embodiment  
     The second embodiment of the present invention relates to a weighing device which is used for shipping salmon (hereinafter, referred to as objects G) as natural objects, the weights of the salmon being unequal, and combines and discharges a plurality of objects G so that the total weight of the objects G is a predetermined weight (final target weight) set as a shipping boxed weight. The weighing device discharges (drops) the combinations thereof into different discharge parts in a simultaneous, parallel manner. 
       FIG. 5  is a front view of a weighing device  100  according to the second embodiment of the present invention.  FIG. 6  is a right side view thereof.  FIG. 7  shows the content of the weight ranks of objects sorted by the weighing device  100 . 
     Weighing Device  100   
     The weighing device  100  shown in  FIGS. 5 ,  6  is provided with two (a plurality of) weighing unit  2   1 ,  2   2 , an unillustrated controlling part  3 , a plurality of discharge parts  4   1-10 , and two (a plurality of) conveying unit  5   1 ,  5   2 . The weighing unit  2   1 ,  2   2  individually measure the weights of the objects G sequentially carried in from an upper process. The controlling part  3  sorts the weighed individual objects to a plurality of predetermined weight ranks based on the measurement result obtained by the weighing unit  2   1 ,  2   2 , combines and selects the plurality of objects G having a total weight that is a predetermined weight in the same weight rank sorted. The discharge parts  4   1-10  are used in order to discharge the plurality of objects G combined and selected. The conveying unit  5   1 ,  5   2  individually circulate the weighed objects G in a plurality of holding containers  51  . . .  51  and discharge the combined and selected objects when the objects reach a prescribed position corresponding to one discharge part  4   x  into which the objects G should be discharged, among the plurality of discharge parts  4   1-10 . As for the holding containers  51 , numeral indications in the figures are partially omitted. 
     In the second embodiment, the objects G carried into the weighing device  100  are salmon. The weighing unit  2   1 ,  2   2  individually weigh these salmon one by one. The weighed salmon are sorted to a plurality of weight ranks, specifically, any one of nine weight ranks of  3 L,  2 L, L,  3 M,  2 M, M,  3 S,  2 S and S shown in  FIG. 7  by the controlling part in order to secure a combination of salmon of the same weight rank whose total weight is a predetermined weight of 10 kg±α (±α: permissible error), which is the final target weight. That is, for the salmon of the same weight rank, the combination of the number of fish corresponding to the weight rank is generated, and the total weight is combined and selected to be the predetermined weight. For example, the salmon of grade L are combined and selected so that the total weight of five salmon is 10 kg±α. The combined and selected salmon are discharged to one discharge part  4   x  specified by the controlling part  3  from the plurality of holding containers  51  . . .  51  individually holding the salmon. In the discharge part  4   x , the salmon are once assembled, and are further discharged to a receiving box B. A worker takes out the receiving box B into which the salmon are dropped in exchange for an empty receiving box B, boxes the salmon in the taken-out receiving box B in a shipping pack box, and applies a grade indication to the pack box. 
     Weighing Unit  2   1 ,  2   2    
     Weighing unit  2   1 ,  2   2 , which are parallelly arranged as shown in  FIG. 6 , are weighing conveyers which convey the objects G continuously carried in by a supply conveyer C 1  and a taking-in conveyer C 2  to a downstream and individually measure the weights of objects. Also, the weighing unit  2   1 ,  2   2  individually supply the weighed objects G to the holding containers  51  . . .  51  of the conveying unit  5   1 ,  5   2  via a timing shutter  21  equipped on the terminal side of each of the conveyers, and output the measurement data signal to the controlling part  3 . The timing shutter  21  is provided with a door which is opened and closed at the bottom and is not shown. The weighed objects G are once held by closing the door. The door is opened with the timing of the empty holding containers  51  passing downward, and the objects G are supplied to the empty holding containers  51 . 
     Controlling Part  3   
     The controlling part  3  sorts the weighed objects G to the predetermined weight ranks, specifically any one of nine weight ranks of  3 L,  2 L,  3 M,  2 M, M,  3 S,  2 S, and S based on the measurement data signal from the weighing unit  2   1 ,  2   2 , and stores the weight ranks and weight data in association with the holding containers  51  to which the weighed objects G are supplied. Also, based on the weight ranks and weight data stored in association with the holding containers  51 , the controlling part  3  selects a combination in which the total weight of only the objects of the same weight rank is the above predetermined weight from all the objects which are held in the holding containers  51  with which any one of the conveying unit  5   1 ,  5   2  is provided and are not yet combined and selected. All the objects G circulated by two conveying unit  5   1 ,  5   2  are combined and selected. Furthermore, the controlling part  3  outputs a control signal to the conveying unit  5   1 ,  5   2  so that a plurality of objects newly combined and selected are discharged to a discharge part  4   x  other than a discharge part used for discharging a plurality of objects previously combined and selected. The objects G after a predetermined time has passed without being combined and selected with the objects G held in the holding containers  51  is compulsorily treated so that the objects G are certainly combined and selected in order to secure the freshness. 
     That is, whenever the controlling part  3  newly combines and selects the objects regardless of the weight ranks of the combined and selected objects, the controlling part  3  selects one discharge part  4   x  which is not used from the plurality of discharge parts  4   1-10 , and outputs to the conveying unit  5   1 ,  5   2  a control signal to cause the objects to be discharged to the discharge part  4   x . Therefore, when the controlling part  3  selects simultaneously a plurality of combinations of a plurality of objects having the total weight being the predetermined weight in the same weight rank, the controlling part  3  outputs a control signal discharging the plurality of combinations simultaneously parallelly to different discharge parts  4   x . The controlling part  3  does not randomly select one discharge part  4   x  to which a plurality of objects G newly combined and selected are discharged from unused discharge parts. The controlling part  3  places high priority in order from the right side discharge part  4   1  in the discharge parts  4   1-10  in  FIG. 5 , and produces a control signal so that the discharge part having the highest priority is always used. 
     The controlling part  3  includes a weight setting section, an integrating section, a calculating section, a storing section, and a discharging control section as in the controlling part  14  of the weighing device  1  according to the first embodiment in order to carry out the above processing. The weight setting section sets a predetermined weight which is a final target weight of a plurality of objects G discharged to the discharge part  4   x . The integrating section integrates the measured weights of the objects G measured by the weighing unit  2   1 ,  2   2  in each of the discharge parts  4   x . The calculating section calculates a final target weight difference in each of the discharge parts  4   x , the final target weight difference being a difference between the integration weight integrated by the integrating section and the final target weight. The storing section stores the final target weight, the integration weight, and the final target weight difference. The comparing section compares the weights of the objects G measured by the weighing unit  2   1 ,  2   2  with the final target weight difference. The discharging control section discharges the weighed objects to the discharge part in which the measured weights are approximate to the final target weight difference based on the comparison result. 
     Discharge Parts  4   1-10    
     As shown in  FIG. 5 , a plurality of discharge parts  4   1-10  is provided along a circulating path R of the holding containers  51 . As shown in  FIG. 6 , the discharge parts  4   1-10  are provided with a conveyance conveyor  41  and a timing hopper  42  provided on the terminal side of the conveyance conveyor  41 . The conveyance conveyor  41  conveys the objects G discharged from the holding containers  51  of the conveying unit  5   1 ,  5   2  in an arrow direction shown in  FIG. 6 , and drops and discharges the objects G into the timing hopper  42 . The timing hopper  42  is provided with a cylindrical hopper main body  421  opened on the upper and lower sides, and a gate  422  closing and opening a lower opening  421   a  of the hopper main body  421 . The lower opening  421   a  is closed by the gate  422 . The objects sequentially discharged from the conveyance conveyor  41  are received from an upper opening  421   b,  and are stored in the hopper. When all of the objects combined and selected are provided in the hopper, the gate  422  is operated to open the lower opening  421   a,  and the objects are dropped and discharged into the receiving box B placed below the timing hopper  42 . 
     Conveying Unit  5   1 ,  5   2     
     As shown in  FIG. 5 , the conveying unit  5   1 ,  5   2  are conveyance conveyors which individually receive and hold the objects G weighed by the weighing unit  2  using the plurality of holding containers  51  . . .  51 , and circulate the objects G along a circulation conveying path R. The conveying unit  5   1 ,  5   2  have a function as the discharging unit for discharging the plurality of objects G combined and selected to the selected discharge part  4   x  based on the control signal from the controlling part  3 . Each of the holding containers  51  is provided with a bottom part  51   a  capable of being opened and closed. When each of the holding containers  51  receives the weighed objects G from the weighing unit  2   1 ,  2   2 , the bottom part  51   a  is closed. When the holding containers  51  holding the objects G combined and selected reach a prescribed position corresponding to the discharge part  4   x  into which the objects G should be discharged, the bottom part  51   a  is opened, and the objects G are discharged to the discharge part  4   x . 
     Operation of Weighing Device  100  According to Second Embodiment  
     The operation of the weighing device  100  according to the above second embodiment will be described. The weights of the objects G carried into the weighing device  100  are individually measured by the weighing unit  2   1 ,  2   2 , and the objects G are individually held by the holding containers  51 . In this case, the controlling part  3  sorts the weight ranks of the held objects G, and stores the weights and weight ranks of the objects G in association with the holding containers  51  holding the objects G. Also, the controlling part  3  selects, from the plurality of discharge parts  4   1-10 , one discharge part  4   x  to which the plurality of objects combined and selected are discharged except for the discharge part used for discharging the objects at this time, and selects a combination of a plurality of objects in the same weight rank whose total weight is 10 kg±α of the final target weight from all the objects G held by the plurality of conveying unit  5   1 ,  5   2 . 
     In this case, in the controlling part  3 , the integrating section integrates the measured weights of the objects G selected from the same weight rank. The calculating section calculates the final target weight difference, which is a difference between the integration weight and the final target weight. The comparing section compares the final target weight difference with the weights of the weighed objects G. The discharging control section discharges the weighed objects G to a discharge part  4   x  of the combination having a final target weight difference approximate to the measured weights based on the comparison result. However, the selection of the objects G and the integration of weight data may be carried out not one by one but collectively for the plurality of objects. For example, the weights of the plurality of containers  51  in which the objects G are individually stored may be added up to be treated as one data. The plurality of objects collectively selected may not be continuous on the conveying path, and may extend the conveying unit  5   1 ,  5   2 . 
     Furthermore, the controlling part  3  opens the bottom part  51   a  of the holding containers  51  and outputs to the conveying unit  5   1 ,  5   2  the control signal for dropping the objects G when the holding containers  51  holding the plurality of objects combined and selected reach above the selected discharge part  4   x . Thereby, the objects G combined and selected are discharged sequentially to the selected discharge part  4   x , and all the objects are stored in the timing hopper  42  corresponding thereto. The objects are then collectively discharged into the receiving box B placed below the gate  422  by opening the gate  422  of the hopper. The worker takes out the receiving box B into which the objects G combined and selected are dropped in exchange for an empty receiving box B, and carries out the boxing operation of the objects G. 
     As described more specifically, for example, all the salmon held in the holding containers  51  . . .  51  are combined and calculated. When the combination L 1  in which the total weight is 10 kg±α is realized for five salmon L 11 , L 12 , L 13 , L 14 , L 15  (all the salmon have grade L) shown in  FIG. 5 , the controlling part  3  combines and selects these salmon. When the discharge parts which are not used for discharging therein the objects previously combined and selected in the plurality of discharge parts  4   1-10  provided are the discharge parts  4   2 ,  4   3 ,  4   5 , then the discharge part  42  having highest priority, that is, the rightmost discharge part  42  is selected as an object discharge place. Thereby, when the holding containers  51  holding the salmon of L 13 , L 14 , L 15  combined and selected circulate and pass above the discharge part  4   2 , the salmon of L 13 , L 14 , L 15  are discharged. 
     The above objects are combined and selected, and are discharged regardless of the sorted weight rank. For example, when the new combination L 2  of the salmon L 21 , L 22 , L 23 , L 24 , L 25  of grade L of the same weight rank having a total weight of 10 kg±α is realized even before the above-described salmon L 11 , L 12 , L 13 , L 14 , L 15  of the grade L are combined and selected and the discharge of the salmon to the discharge part  4   2  is completed, the salmon of the combination L 2  are combined and selected. The discharge part  4   3  having the highest priority in the discharge parts  4   3 ,  4   5  . . . which are not used at this time is selected as the object discharge place, and the discharge of the combination L 2  is indicated. That is, even when the combinations L 1 , L 2  of a plurality of objects having a total weight that is a predetermined weight in the same weight rank are simultaneously selected, the objects are simultaneously parallelly discharged to different discharge parts  4   2 ,  4   3 . When a plurality of combinations having the total weight being the above predetermined weight in a different weight rank are realized, of course, the objects are simultaneously parallelly discharged to different discharge parts. 
     Features of Weighing Device  100  According to Second Embodiment  
     First, the weighing device  100  according to the above second embodiment is characterized by combining and selecting the plurality of objects having the total weight being a predetermined weight in the same weight rank regardless of the weight rank, and by selecting a discharge part  4   x  which is not used as the object discharge place from the plurality of discharge parts  4   1-10  each time. Therefore, another plurality of objects newly combined and selected can be discharged without having to wait until all of the objects previously combined and selected in the same weight rank are discharged. As a result, the discharge cycle of the objects combined and selected can be speeded up to make the processing efficient. Also, this shortens the holding time of the objects in the conveying unit  5   1 ,  5   2  and prevents the disadvantageous deterioration of the objects during the circulation of the objects. The discharge parts are used in common without providing the discharge part in each of the weight ranks, and thereby the total number of the discharge parts can be reduced, and the installation space and cost of the discharge parts can be suppressed. 
     Secondly, the weighing device  100  according to the above second embodiment is characterized in that when a plurality of combinations of a plurality of objects having a total weight that is a predetermined weight are simultaneously selected in the same weight rank, the combinations are simultaneously parallelly discharged to different discharge parts. Therefore, even when a plurality of combinations are selected in the same weight rank, the objects can be discharged for each of the combinations regardless of the discharge situation of the object of the other combinations, and as a result, the efficiency of the object discharge processing can be enhanced. 
     Thirdly, the weighing device  100  according to the above second embodiment is characterized by placing the priority to the arranging order of the plurality of discharge parts  4   1-10  arranged along the circulating path R and using the discharge part to which the high priority is placed when the combined and selected objects are discharged. Therefore, since the discharge parts into which the objects G are dropped are concentrated in a narrow range along the arranging order thereof, the moving distance of the worker who carries out post-processing of the discharged objects is reduced, and as a result the work burden is reduced. 
     Fourthly, the weighing device  100  according to the above second embodiment is characterized by being provided with the plurality of conveying unit  5   1 ,  5   2 , and by combining and selecting all the objects circulated by the conveying unit  5   1 ,  5   2 . Therefore, the weighing device  100  can enlarge the population of the objects G combined and selected, and can respond to a large number of weight ranks while securing the accuracy of the quantitative weighing. 
     Modifications of Second Embodiment  
     (1) The discharge part  4   x  used for discharging the objects is selected from all the plurality of discharge parts  4   1-10  regardless of the weight ranks in the above second embodiment. For example, the combination of grades  3 L,  2 L, L may be selected from the discharge parts  4   1-3 . The combination of grades  3 M,  2 M, M may be selected from the discharge parts  4   4-7 . The combination of grades  3 S,  2 S, S may be selected from the discharge parts  4   8-10  to limit the discharge parts capable of being selected according to the weight ranks. 
     (2) In the above second embodiment, the object discharge place is selected by the priority placed to the arranging order of the discharge parts  4   1-10 . However, how to place the priority can be variously changed according to the situation. For example, when two workers box and take charge of the discharge parts  4   1-5  and  4   6-10  respectively, the equalization of the quantity of work is considered to be attained by placing the priority in the order of the discharge parts  4   1 ,  4   6 ,  4   2 ,  4   7 ,  4   3 ,  4   8  . . . . 
     (3) In the above second embodiment and the above modifications (1), (2), the weight data of the objects G individually weighed by the weighing unit  2   1 ,  2   2  are individually stored in association with the holding containers  51  individually holding the objects G. However, the weight data of the objects G held by the plurality of holding containers  51  which are continuous on the conveying path of the conveying unit  5   1 ,  5   2  may be stored as a mass of data; the plurality of objects G may be successively discharged to one discharge part; and the mass of weight data may be integrated by the integrating section. This modification can attain the speed-up of the discharge processing and can shorten the holding time of the objects in the conveying unit  5   1 ,  5   2 , which circulates the objects G. As the mass of data, the total weight data of the plurality of objects may be employed. 
     The weighing device of the present invention is not limited to the above first and second embodiments, and it is apparent that various changes may be added without departing from the scope of the present invention. 
     The weighing device of the present invention can contribute to quantitative weighing in which as well as natural objects, various objects and the like having various weights are collected to predetermined collection places.