NZ199446A - Grading articles by weight-conveyor with electronic weigher - Google Patents

Description

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S'1 ' fl4 DEC 1984 I - •* L : 3 ,«-i » = »» = »• 6 S 7jr tte: , a... )Pi^ I I „ " IK.«^C*~"-,UVUia'~ Patents Form No.5 v NEW ZEALAND PATENTS ACT 1953 COMPLETE SPECIFICATION "METHOD AND APPARATUS FOR SORTING BY WEIGHT WITH ELECTRONIC WEIGHING DEVICE" -I-WE KABUSHIKI KAISHA MAKI SEISAKUSHO, a Japanese company of 6 30 Sasagase-cho, Hamamatsu-shi, Shizuoka-ken, Japan, hereby declare the invention, for which-I/we pray that a patent may be granted to -me/us,.and the method by which it is to be performed, to be particularly described in and by the following statement:- 1 99446 •Tomyoma Patont Offioo - ±/\- SPECIFICATION Title of the Invention: METHOD AND APPARATUS FOR SORTING BY WEIGHT WITH ELECTRONIC WEIGHING DEVICE Abstract of the Disclosure: A method and an apparatus for sorting agricultural produce and the like by weight thereof using an electronic weighing device in combination with a conveyer system and discharge devices. The object to be sorted is put piece by piece on containers which are mounted on a conveyer through mounting members at even spacing intervals. When each container comes to travel past the weighing device, the container is kept vertually in a non-contacting floating state, free from being affected by vibration of the conveyer operation, with clearances provided around the mounting part between the container and the mounting member of the conveyer system. This permits an accurate sorting operation. Further, with an electromagnetic force balance device used for the electronic weighing device, the degree of sinking displacement of a weighing receiver plate of the weighing device is only 0.1 mm or thereabout. The weighing device, therefore, is quickly stabilized at a zero point so that a sorting operation can be carried out at a high speed. "i 19944 6 BACKGROUND OF THE INVENTION FIELD OF THE INVENTION: This invention relates to a method and an apparatus for sortingoby weight and more particularly to a method and an apparatus whereby agricultural products mainly including fruits and others are weighed by placing them piece by piece or one by one on containers and are classified and sorted by weight.

DESCRIPTION OF THE PRIOR ART: For sorting by weight of agricultural products such as fruits, apparatuses are known and have been used in general. In these conventional weight sorting apparatuses for fruits, weighing instruments of the lever and spring balancer types have been employed.

Further, in recent years, there appeared an automatic weight sorting apparatus which uses a load cell type weighing instrument in combination with the conveyor arrangement of the conventional fruit weight sorting apparatus.

In these conventional apparatuses for sorting fruits by weight, cup ttaction shafts are mounted with even spacing on an endless chain arrangement travelling in a circulating manner. A conveyor system is formed with cups attached to the traction »• . 199 446 Taniyomo—Potent—Offieo - 3 - • shafts in a hinged manner. Each of the cups is provided with a finger which is arranged to slide on a weighing instrument. In another example of - the conventional apparatuses, cups or weighing baickets are tiltably attached to supporting members which constitute a Roberval mechanism. The supporting members are secured to the chain at even spacing intervals to form a conveyer system with weighing cups. In this case, each of the supporting members is provided with a finger or a hook or a sliding piece called a sliding pin which protrudes from a part of the supporting member to slide on the weighing instrument while the conveyer system is on the move, so that the fruit can be classified and sorted by weight thereof.

The conventional arrangement thus has cups or weighing buckets kept horizontally secured to the chain through supporting members either by hinges or fulcrum pins. Therefore, the travelling vibration of the chain is transmitted as it is to the sliding pieces which are arranged at the cups or weighing buckets to serve as weight detecting elements. Then, the weight detecting elements travel sliding on the weighing instrument while they are thus vibrating. It has been a shortcoming of the conventional arrangement that a great weighing error resulting from this vibrant v r / sliding movement on the weighing instrument thwarts accuratg -- sorting by weight. \ Further, in the conventional arrangement, each of the*" cups or weighing biickets is carried by a fulcrum pin or a hinge in linkage with a plurality of component members. The rotative movement or frictional resistance of one linkage section differs from another while there are provided hundreds of cups or weighing 199446 1' '• Toniyoma Potent Office - 4 - buckets in each sorting arrangement. Hence, it has been another 3 shortcoming of the conventional arrangement that weight cannot be measured with precise accuracy even if the weight of many cups or weighing buckets were uniformalized.

An arrangement where a small conveyer is provided at the weighing receiver plate of a weighing instrument for conveying the object to be weighed to the instrument to accomplish weighing piece by piece has been also known. Generally", this arrangement is employed in automatically screening an industrial product to find whether the weight thereof is at a prescribed value or deviates therefrom. A weighing instrument using a conveyer of this type is capable of weighing in a non-contact manner the object to be sorted by separating it from the conveyer piece by piece. However, since a conveyer is incorporated in the weighing mechanism, vibration resulting from addition or subtraction of a load and vibration of the conveyer itself greatly affects weighing accuracy.

The above stated shortcomings of the conventional known arrangements have rendered the results of sorting operations unsatisfying. This has prevented a high speed sorting operation at an increased conveyer speed. To accurately sort a great amount of product, therefore, it has been necessary to have a plurality of weight sorting apparatuses operated at a lowered conveyer speed and thus at a reduced capacity. v ■ ''( vSN ' ' Summary of the Invention: The present invention is directed to the elimination of these shortcomings with the advanced technology of a measuring 199446 T«ailiyamo—Patent—Office - 5 - device using an electronic weighing instrument which is capable of covering a wide range of weight through a very slight degree of displacement of a weighing receiver plate. It is therefore a general object of the invention to provide a sorting apparatus in which receiving pan shaped containers which are arranged to receive the object to be sorted and classified piece by piece are of simple structure and of uniform weight; the weight of the object can be measured and sorted at a high speed and with a high degree of accuracy; and yet the structural arrangement of the apparatus facilitates weight adjustment and operation thereof.

In accordance with the present invention, the mechanism whereby each of the containers provided with a receiving pan which permits the object to be sorted to be put thereon one at a time and is mounted on a mounting member of a conveying means/is arranged such that, when the container travels over a weighing device, both the container and the weighing instrument are unaffected by the vibration of conveying means (the vibration is not transmitted). More specifically, the mounting part of the container and the above stated mounting member are coupled in such a manner that one is arranged to be larger than the other to provide clearances above and below, left and right and before and after the coupling part; the container has; a sliding face in thev bottom part thereof; and the sliding face is arranged to enable the container to independently stand thereon without tumbling when the container comes into a state of not contacting the mounting member. The; ^ container is further provided with a vertical face either at/,,, « V ,(> 199446 Taniyomo Patant Office 6 the mounting part or at another part thereof. The vertical face is facing backward while a part of a circumference of a pushing member is arranged to be in contact with this vertical face in such a way as to keep clearances in front and in rear of the container. A conveyer system with containers is formed in this manner.

The weighing device according to the invention uses an electronic weighing instrument having a weighing receiver plate which is not much displaced upward and downward by the largeness and smallness of the load. The weighing receiver plate is provided with a sliding measurement rail which corresponds to the sliding face of the above stated container. The height of the receiver plate is determined to leave upper and lower clearances between the above stated mounting part of the container and the mounting member. each container is not in contact with the mounting member when object to be sorted placed thereon. It slides while the vertical face provided in a part of the container is horizontally pushed by a part of the circumference of the pushing member in the travelling direction thereof. Therefore, there is no part that has any adverse effect on the vertical loadvof the container. Further, since the invented arrangement effectively prevents the vibration of the conveying means from being transmitted, a sorting operation by weight can be carried out at a high degree of accuracy. Besides, the high weighing accuracy permits ai With the weighing device which is arranged in this manner combined with a conveyer system which is provided with the containers the container slides over the weighing device with the t 99446 Taniyaino Patent Of floe - 7 - in the conveyer speed to increase the processing capacity per minute.

The above and further objects, features and advantages of the invention will become apparent from the following detailed description of preferred embodiments thereof taken in connection with the accompanying drawings.

Brief Description of the Drawings: All the accompanying drawings represent embodiments of the present invention. Fig. 1 is a plan view showing a first embodiment of the invention which is arranged to have containers linearly travel in one row in a circulating manner. Fig. 2 is a side view schematically showing the arrangement of the first embodiment. Fig. 3 is a plan view showing a second embodiment of the invention which is arranged to have the containers linearly travel in plural rows in a circulating manner. Fig. 4 is a side view schematically showing the second embodiment. Fig. 5 is a plan view showing a weight sorting apparatus arranged to have the containers horizontally travel in a elliptically circulating manner. Fig. 6 is a sectional view schematically showing the essential parts of a sorting and discharge section of the apparatus shown in Fig. 5. Fig. 7 is a plan view showing a weight sorting apparatus of the rotary type arranged to have the containers horizontally travel in a circulating manner. Fig. 8 is a sectional view schematically showing the essential parts of the arrangement shown in Fig. 7. Fig. 9 is a schematic view of the essential parts of the present weight sorting apparatus.

Figures 10 and 11 are schematic views showing the containers as 1 99446 T-oniyomo Potent Office - a - on the move past the weighing section of the first embodiment. Fig. 12 is a sectional view showing the weighing section of the first embodiment as in a state of having a container conveyed past the weighing section. Fig. 13 is a sectional view showing the container conveying device of the first embodiment at the sorting and discharge section thereof. Fig. 14 is a plan view showing discharge devices provided beneath the container conveying path of the first embodiment. Fig. 15 is a side view*showing the weighing section of the second embodiment. Fig. 16 is a side view showing the conveyer system of the second embodiment provided with a container. Fig. 17 is a plan view of Fig. 16. Fig. 18 is a side view showing the container of the second embodiment as in a state of being conveyed at the weighing section. Fig. 19 is a sectional view of Fig. 18. Figures 20 and 21 are schematic views showing the discharge device of the second embodiment. Fig. 22 is a schematic view showing an electronic weighing instrument as an embodiment example.

Detailed Description of Preferred Embodiments: Referring to Figures 1, 2, 3, 4, 5, 6, 7 and 8 which all illustrate the embodiments of the present invention, the mode of embodying and practising the invention varies with the kind of the object to be sorted, the quantity of the object to be processed, the scale of the sorting operation, the size of the available space for installation of the sorting apparatus, the layout of the apparatus, etc.

A weight sorting apparatus 1 may be arranged in varied 1 99446 Taniyama Patent Office - 9 - manners according to the invention as represented by Figures 1, 3, 5 and 7 respectively. The apparatus 1 as shown in these drawings has a supply section 3 which is arranged to feed the object 2 to be sorted; a weighing section 4; and a sorting and discharge section 5. Each of these sections 3, 4 and 5 is arranged to extend to a necessary length.

The apparatus further includes containers 6 each being * arranged to carry one piece of the object to be sorted. Each container 6 is provided with a receiving pan part 7, a sliding face 8 and a mounting part 9. The container 6 may be either arranged to have the receiving pan part 7, the sliding face 8 and the mounting part 9 formed into one unified body or may be arranged to have these parts assembled as separate parts with the receiving pan part 7 arranged to be supported jointly by the mounting part 9 and the sliding face 8 and thus to be tiltable to one side.

One of these different ways of arranging the container 6 is selected according to the mode of embodying the invention.

The apparatus has a conveying means 10, which includes either a conveyer chain 11 or a rotating body 12 such as a turntable according to the mode of embodying the invention. There is provided a mounting member 13 for each of the above stated containers 6. The mounting member 13 is combined with the above stated mounting part 9 of the container 6 leaving clearances a, b, c, d, e and f above, below, on the right and left sides and on the front and rear sides of the mounting part 9 to permit the container 6 to be freely movable within the range defined by these clearances. 1 9 94 4 6 Toniyomo Potent Office - 10 - One of the combined pair consisting of the mounting part 9 of the container 6 and the mounting member 13 is arranged to be larger than the other for obtaining the above stated clearances. Their shapes and structural arrangement vary with the mode of embodying the invention.

The container 6 is provided with a vertical face 15 either at the above stated mounting part 9 or at some other part. The vertical face 15 is facing backward and is arranged to ha.V§ a part of the circumference of a pushing member 16 in contact therewith. The pushing member 16 is arranged in this manner to maintain the above stated clearances e and f between the mounting member 13 and the mounting part 9 of the container 6. Each being thus arranged, many containers 6 are mounted on the conveying means 10 at even intervals to form a conveyer system 14 with containers 6. The system 14 travels in an endless circulating manner. The above stated vertical face 15 is disposed below the receiving pan part 7 of the container 6 and above the sliding face 8, i.e. between the receiving pan part 7 and the sliding face 8, and is arranged either in front, in the middle or in the rear part of the container 6 according to the mode of embodying the invention.

The above stated pushing member 16 is preferably a circular body of low frictional resistance such as a bearing, a roller or a ball. In some embodiment of the invention, however, such a pushing member 16 may be replaced with a non-rotating shaft to have the vertical face 15 pushed from outside by the non-rotating shaft. In such a case, therefore, the mounting member 13 may be arranged to serve also as pushing member 16. 199446 ■Taniyama Patent Qffioo - 11 - The vertical face 15 is disposed in front of the mounting part 9 and is arranged to face backward there. It is economical and preferable that the pushing member 16 is arranged in the form of a roller which enters the mounting part 9 with the mounting member used as shaft.

It is possible to reverse the above stated relation of a vertical face of the container 6 to the circular front face of the pushing member 16 by making the front of the pushing member 16 into a vertical face while providing the container 6 with a circular protrusion or a roller in place of the vertical face 15.

The weighing section includes an electronic weighing instrument 17 and a weighing receiver plate 18. The receiver plate 18 has sliding measurement rails 19 arranged thereon to correspond to the sliding face 8 of the container 6. The weighing instrument 17 with the receiving plate 18 is disposed beneath the container conveying path 20 of the conveyer system 14 having the containers. The height of the weighing instrument 17 is arranged such that the clearances a, b, c and d mentioned in the foregoing are retained between the mounting member 13 and the mounting part 9 of the container 6 when the container 6 slides on the sliding measurement rails 19. In other words, the weighing instrument is disposed at a height at which the container 6 is lifted up to a slight degree away from the mounting member 13.

Since the displacement of the weighing receiver plate 18 takes place only to a very slight degree when a vertical load is imposed on the plate 18, the clearance a is retained even 1 99446 Toniyama Patont Offioo - 12 - when the container with the object to be sorted placed thereon comes onto the sliding measurement rails 19, so that .the whole weight of the container 6 can be received by the receiver plate 18 through the measurement rails 19 for accurate measurement of the weight.

The electronic weighing instrument 17 is either a force balance type weighing instrument using an electromagnetic force * balance device or a load cell type weighing instrument using a load cell or a weighing instrument using a differential transformer. In the case of a high speed weighing operation where 150 to 210 pieces are to be processed per minute, that is, 2.5 to 3.5 pieces per second, the load causes the weighing receiver plate 18 to move up and down. This tends to have vibration take place due to inertia. It is therefore preferable to employ a force balance type weighing machine using an electromagnetic force balance device for such a high speed operation.

The electromagnetic force balance device 21 is mounted on a lever 22 to which the weighing receiver plate 18 is attached. The device 21 is arranged to hold and balance the weighing receiver plate 18 always at a prescribed level on a fulcrum 23.

When the receiver plate 18 is caused to sink by a load, the device 21 acts to lift it up as much as it has sunk. With the device 21 employed, therefore, vibration can be absorbed even where a weighing operation is carried out at a high rate exceeding 3 pieces/sec, so that the weighing can be accomplished at a high degree of accuracy.

The electronic weighing instrument 17 is provided with 199446 Toniyomo—Patent—Office - 13 - entrance guide rails 24 and exit guide rails 25 which are disposed before and after the sliding measurement rails 19. The rails 24 and 25 are arranged to have the container 6 come onto and leave from the rails 19 smoothly without giving any impact and vibration to the weighing instrument 17 with the heights of these rails adjusted to the height of the sliding measurement rails 19.

The entrance and exit guide rails 24 and 25 may be mounted on the frame of the conveyer system whicfi is equipped with the containers. However, in view of the importance of the positions of the rails 24 and 25 in relation to the sliding measurement rails 19, the rails 24 and 25 ^re preferably mounted on the same base as the electronic weighing instrument 17.

The entrance guide rails 24 are arranged to scoop up the container 6 of the conveyer system 14 from below the sliding face 8 thereof and to have it slide and travel horizontally at a height that keeps the above stated clearances a and b. Meanwhile, the exit guide rails 25 are arranged to receive the container 6 as it comes travelling over the sliding measurement rails 19 without changing the height of the container 6 and, after detachment of it from the rails 19, to smoothly guide it by lowering the height of it till the clearance a of the mounting part 9 becomes zero and until the mounting part 9 is supported by the mounting member 13 by coming into contact with the latter.

A clock means 26 is arranged to produce a pulse signal in synchronism with the container 6 and is arranged in association with the conveyer system 14 which is equipped with the containers. A known clock means may be used as the clock means 26. The 1 99446 •Taniyoma Patent Offioo - 14 - timing of the clock means 26 is adjusted in such a manner that the pulse signal is issued when the container 6 has arrived at a predetermined point on the electronic weighing instrument 17.

The weighing device of the invented apparatus is provided with an amplifier 27, which is arranged to amplify an electrical signal proportional to the weight of the load imposed on the weighing receiver plate 18 of the electronic weighing instrument 17. The output signal from the amplifier 27 is converted by a converter 28 into a digital signal which is proportional to the weight.

The electronic weighing instrument 17, the amplifier 27 and the converter 28 constitute the weighing device. The weighing device is connected to the output terminal of the clock means 26 and to an arithmetic unit 29.

The weighing device is arranged as follows: The instant the container 6 comes to slide onto the sliding measurement rails 19 of the electronic weighing instrument 17, the sudden loading causes the weighing receiver plate 18 to somewhat vibrate. In response to this, the above stated clock means produces the pulse signal. With the pulse signal obtained, the converter 28 produces the digital signal corresponding to the weight at a point of time when the container 6 has come to smoothly travel on the sliding measurement rails 19 with the vibration having been gradually absorbed there.

The arithmetic unit 29 is connected to the output terminal of the converter 2 8 of the weighing device and the output terminal of the clock means. The arithmetic unit is mainly t 99446 •Taniyama Patont Office -1--3 composed of a comparison circuit 30; a preset circuit 31 provided for setting standard weight grading values; a discharge position setting circuit 32 for setting a discharge position for each grade; and a shift circuit 33 which is arranged to transmit a discharge instruction signal to each of the set discharge positions in synchronism with the containers. A known arithmetic unit may be employed as the arithmetic unit 29.

A reference numeral 34 indicates discharge devices which are arranged at the sorting and discharge section 5 of the conveyer system 14 having the containers. The discharge devices 5 are disposed either on one side of or beneath the container conveying path 20 and are allocated to the pieces of the object of different grades of weight. A known discharge arrangement is usable for each of the discharge devices 34.

In the arithmetic unit 29, the digital signal which is produced from the converter 28 in proportion to the measured weight is counted at the comparison circuit 30 and is compared with the preset values of grades to determine an applicable grade. Then, a discharge instruction signal is transmitted to one of the discharge device 34 located at the position of the applicable grade.

The discharge devices 34 are arranged to discharge and take out each piece of the object 2 to be sorted from the receiving pan part of each containers 6 at a predetermined position. The discharging action of the discharge device 34 is accomplished in one of varied manners including a discharging action performed by tilting the container 6 to one side; a 1 99446 Taniyamo Patent Office ~ 1° discharging action by tilting the rear side of the container 6 straightly downward; another discharge action by pushing the object 2 to one side without tilting the container 6; and so on. A suitable discharging manner should be selected according to the mode of embodiment of the invention in respect to the conveyer system having the containers.

A counter which counts the individual sorted pieces of the object by grade and a printer which is arranged to record sorting data may be connected to the arithmetic unit 29 respectively.

Example 1 Figures 10, 11, 12, 13 and 14 further illustrate the conveyer system with containers and the discharge device used for the weight sorting apparatus shown in Figures 1 and 2. In this embodiment of the invention, the receiving pan part 7 of each container is arranged to be tiltable to one side. The sliding face 8 and the mounting part 9 of the container are formed into one unified body to serve as supporting body 35 for the pan part 7. A tilting mechanism 36 which is arranged to tilt the receiving pan part 7 is incorporated in the supporting body 35. The receiving pan part 7 is mounted on and connected to the supporting body 35 and to the tilting mechanism 36 through a link 37 and a pin 38. The tilting mechanism 36 is arranged to constantly hold the receiving pan part horizontal by means of a spring 39. In discharging the object to be sorted, the receiving pan part 7 is tilted by having a pin 40 which protrudes downward slided by the discharge device 34 against the force of the spring % Taniyama Patent—Office 17 39. The supporting body 35 is mounted by £wo,mounting members 13 or holes of other shapes. However, the hole must be of a size determined by adding clearances a, b, e and f to the outside diameter of the mounting member 13. In the arrangement shown in Pig. 10, the vertical face 15 is provided in the rear of the supporting body 35. Meanwhile, a roller 41 which is rotatably attached to the chain 11 serves as pushing member for pushing the vertical face 15 to have the container horizontally conveyed while maintaining the clearahces e and f. In the case of Fig. 11, the mounting part 9 is formed to have a square hole 42. The vertical . face 15 is formed on the front side, of the square hole 42 and is arranged to face backward. Meanwhile, a freely rotatable roller 41 is attached to the mounting member 13 which is made of a round rod and the roller 41 is used as pushing member. Fig. 12 represents an arrangement in which the container 6 is arranged to have clearances c and d on the left and right sides thereof while it is travelling in a sliding manner on the sliding measurement rail 19 of the electronic weighing instrument 17. However, when the container 6 is travelling other part of the .travelling path than the weighing section, the container ^ is arranged to be supported on tapered parts 43 provided on both sides thereof and thus to be kept in the middle of the chain conveyer.

Figures 13 and 14 show the discharge device 34 provided beneath the container conveying path 20. The discharge devicie .34 comprises which are made of round rods and are attached to the ;>c'hain 11 with the mounting members 13 piercing through the mounting >part 9.; The mounting part 9 may be formed to have round.or square holes - -/m ■ ■ - - ;. - ■ ■ -. ■ ■ ^ ' • i ■ . . • '*.-y ■ '-'.si • '-r ^ -Taniyama Patent Office -18 - a lever 44 which is arranged to shift the moving direction of the pin 40 provided in the tilting mechanism of the container; a rotary solenoid 45; and a tilting cam 46. A discharge instruction signal which is produced by the shift circuit 30 of %he'iarithmetic unit 29 and is transmitted in synchronism with the container 6 actuates the rotary solenoid 45 to cause the lever 44 to turn to guide the pin 40 to the tilting cam 46. The pin 40 is'slided by this and the receiving pan part 7 is tilted to discharge the object 2 to be sorted.

Example 2 Figures 15, 16, 17, 18 and 19 show the conveyer system with containers used for the weight sorting apparatus shown in Figures 3 and 4. In this embodiment, the front side of each mounting member 13 which is coupled with the container is connected through a hinge to each of mounting metal pieces 47 which are provided on the chain 11 at even spacing intervals. The object to be sorted is arranged to be discharged by tilting downward the rear side of the container. The container 6 has the receiving pan part 7 disposed in the upper part thereof, the sliding face 8 disposed in the lower part and the mounting part 9 arranged to pierce through a body portion disposed between the receiving pan part 7 and the sliding face 8. These parts are formed into one unified body. The mounting member 13 is formed with a vshaft 48 which is inserted into the above stated mounting part 9 and an arm 49 which carries the shaft 48. The mounting part 9 may be arranged to have round or square holes or holes of ——I — - - i i i 11 ■ ii ■■ i if ii ■ i ■ 1111 ■" i> 11 ii i !■ i iiwir—mmrfnifiiw iii»i if iihiibi ■ " 199446 Toniyoma Patent Officu - 19 - other shapes in the same manner as in the first embodiment example.

However, the size of the hole must be determined by adding the clearances a, b, e and f to the outer diameter of the shaft 48.

The hole disposed on the front side of the mounting member 9 is shaped into a square hole 42 and is arranged to have a vertical face 15 formed on the front side thereof, the vertical face 15 thus facing backward. Meanwhile, a flange roller 50 is rotatably - r mounted on a shaft 48a and is thus arranged to serve as pushing member. Another shaft 48b extends to protrude to the outside of the arm 49 and is arranged to be carried by a running rail 51.

With the shaft 48b arranged in this manner, the container travels while being kept horizontal by this.

The front side of the arm 49 is mounted on the chain 11. It forms a hinge 52 jointly with one of the mounting metal pieces 47 which are attached to and evenly spaced on the chain 11.

Figures 20 and 21 show the discharge device 34 which is disposed below the container conveying path 20 on one side thereof. A / portion of a running rail 51 is cutout here. The cutout portion of the rail 51 is replaced with an ascending-and-descending rail 53, which is arranged to be movable up and down by means of a solenoid 54. The rail 53 has its upper surface 53a normally kept at the same level as the running rail 51. A discharge instruction signal transmitted in synchronism with the container actuates the solenoid 54. The solenoid 54 then causes the rail 53 to ascend to shift the travelling path of the arm shaft 48b to a downward direction. This causes the container 6 to tilt with the rear side thereof downward so that the object to be sorted is discharged there. 1 99446 Example of the Electronic Weighing Instrument: Figures 9, 15 and 22 show the electronic weighing instrument 17 which is provided with the electromagnetic force balance device 21 to be used for the various types of the weight sorting apparatus 1.

The electronic weighing instrument is arranged in the following manner: A lever 22 is horizontally arranged to perpendicularly cross a stand 55 which is secured to and straightly erected on a base. A fulcrum part 55a protrudes from a part of the stand 55. The lever 22 and the fulcrum part 55a are connected to each other by a pair of left and right plate springs 56 to form a fulcrum 23. Meanwhile, one end part 22a of the lever 22 which is located a little away from the fulcrum 23 and a receiving member 57 which extends toward the lower part of the weighing receiver plate 18 are connected to each other by a pair of left and right plate springs 58 to give a weight point 59. The upper and lower parts 55b and 55c of the stand 55 are respectively connected to the upper and lower parts 57a and 57b of the receiving member 57 by means of four plate springs 60 above and below and in parallel with the lever 22. Each of the plate springs 60 is reinforced in the middle portion 60a thereof.

This arrangement provides the function of the stay of a Roberval mechanism. Above the weighing receiver plate 18, the sliding measurement rail 19 which corresponds to the sliding face 8 of the container 6 is arranged covering a distance shorter than the mounting interval P of the container 6.

The lever 22 has a balancing core 61 of the electro- 19 94 46 -Toniyama Patont Offioo ~ magnetic force balance device 21 mounted on the fore end part 22b thereof. A coil 62 to be coupled with this core 61 is mounted on a coil stand 63 through the base to form a force point 64 of an electromagnetic force. A reference numeral 65 indicates a differential transformer which is attached to a part of the lever 22 to serve as displacement detector.

When a load imposed on the sliding measurement rail 19 causes the lever 22 to slant even to a iight degree, there is produced a very small displacement signal (a voltage signal) at the differential transformer 65. This displacement signal is amplified by an amplifier 27 and is converted into a current. The current thus obtained is applied as exciting current to the coil 62. Then, the lever is balanced by an electromagnetic force developed at the coil 62.

In accordance with the present invention, as described in the foregoing, the containers which are arranged to carry piece by piece the object to be sorted are not fixed to the conveying means such as a chain but are arranged to have clearances left above, below, on the left and right sides and on the front and rear sides thereof and to have a sliding face provided at the bottom thereof. Each of the containers is arranged such that it independently stands and is horizontally pushed on its vertical face by a pushing member which does not have much frictional resistance during its sliding travel over the electronic weighing instrument. Therefore, the load imposed on the electronic weighing instrument is precisely proportional to the weight of the object to be sorted, so that the weight can be measured at a 1 9 94 46 Toniyomo Patent Office - 22 - high degree of accuracy.

Further, with the above described electromagnetic force balance device used for the electronic weighing instrument, the degree of sinking displacement of the weighing receiver plate, or the sliding measurement rail, is only 0.1 mm or thereabout. Therefore, the weighing instrument is quickly stabilized at a zero point to permit a sorting operation at a high speed.

Claims (14)

WHAT WE CLAIM IS:

1. A method for sorting objects on the basis of their weights, using apparatus comprising an electronic weighing device and a conveyor system having a plurality of containers each for carrying one object, each container being supported by conveyor means serving to advance each container in sequence to the weighing device and then through a succession of discharge points, the apparatus being arranged to discharge a carried object at one of the discharge points appropriate for the determined weight of that object, the arrangement being such that at the weighing device each container is lifted clear of the conveyor means so as to be supported solely by the weighing device whilst weighing is being performed, characterised in that the container is advanced by the conveyor means whilst being supported solely by the weighing device by means of a freely rotatable roller which imparts an advancing force in a generally horizontal direction on the container.

2. A method according to claim 1 and in which the weighing device has a slide rail along which each container is in turn slid whilst being supported solely thereby to allow weighing to be performed, characterised in that whilst a container is supported solely by the slide rail, there is clearance between the container and the conveyor means which supports the container other than at the weighing device, which clearance allows the container to move upwardly, downwardly, to either side or forwardly with respect to the conveyor means. . -•;/ > ' 19944 - 24 -

3. A method according to claim 1 or claim 2, further characterised in that a clock signal is generated in synchronism with a container being supported by the weighing device, and in that the determined weight is processed in conjunction with the clock signals generated as the conveyor means is operated to advance the containers, a discharge signal being produced to actuate discharge means at the appropriate discharge point for a particular object when the container carrying that object is determined as being present at that discharge point.

4. A method according to claim 3, characterised in that the weighing device determines the weight of a container and the object carried therein, the determined weight being processed to classify the weight of a carried object into one of a number of pre-set grades of weight corresponding one to each discharge point, a discharge signal for the discharge point appropriate for the classified weight being produced by processing the classified weight in conjunction with the clock signals generated as the conveyor means is operated to advance the containers.

5. A method according to claim 3 or claim 4, characterised in that generation of the discharge signal operates the discharge means either to tilt a container sideways or to swing downwardly with respect to the conveyor means, in either case to discharge a carried object from the container.

6. Apparatus for sorting objects on the basis of their weight, which apparatus comprises an electronically-controlled \^eighing device, a conveyor system having a plurality of containers each adapted to carry one object to be sorted, each container being supported by conveyor means arranged to - 25 - 199446 advance the containers in sequence to the weighing device and then through a plurality of spaced discharge points, discharge means being provided at each discharge point to discharge a carried object if a discharge signal is directed to that discharge means, and processing means arranged to receive an electric signal from the weighing device and an electric clock signal generated in synchronism with operation of the conveyor means, the processing means generating said discharge signals, characterised in that each container has a receiving pan part, a sliding face and a mounting part including two apertures extending transversely of the mounting part and spaced apart in the direction of advancement of the container, and in that the conveyor means has a plurality of mounting members two associated with each container respectively, with each mounting member passing with clearance through an aperture of the container mounting part, so that each container is normally supported by two mounting members but may be lifted clear thereof, the electronic weighing device having weighing means adapted to co-operate with the sliding face of the container thereby to lift a container clear of its two mounting members and wholly to support the container and any object carried thereby so as to permit the weighing thereof, there being a freely rotatable roller provided to impart a generally horizontal advancing force on the container mounting part so as to slide the container sliding face along the weighing means on operation of the conveyor means whilst the container is supported by the weighing means. - 26 - 19944 6

7. Apparatus according to claim 6, further characterised in that the mounting member and container mounting part are arranged to define such clearances therebetween as permit the container to move upwardly, downwardly, to either side or forwardly with respect to the mounting member when the container is supported wholly by the weighing means.

8. Apparatus according to claim 6 or claim 7, further characterised in that the weighing means of the weighing device is in the form of a slide rail along whibh each container is in turn slid as weighing is performed, there being guide means to lift each container clear of its mounting member and on to the slide rail of the weighing device arid then to receive each container from the slide rail and lower each container back on to its mounting member.

9. Apparatus according to any one of claims 6 to 8, characterised in that each container has a supporting body defining the sliding face and the mounting part including two spaced apertures, the receiving pan part being pivotally connected to the supporting body to permit pivoting of the pan part at a discharge point to discharge a carried object.

10. Apparatus according to any one of claims 6 to 8, characterised in that the two mounting members associated with each container are carried by an arm pivotally connected to the conveyor means, both the arm and its associated container pivoting relative to the conveyor means at a discharge point to discharge a carried object.

11. Apparatus according to any one of claims 6 to 10, further characterised in that the freely rotatable roller has its axis substantially horizontal, the periphery of - 27 - 1994^6 the roller engaging a generally vertically extending abutment face of the container mounting part.

12. Apparatus according to any one of claims 6 to 11, characterised in that the freely rotatable roller is mounted on one of the mounting members extending through the apertures in the container mounting part.

13. A method for sorting objects on the basis of their weights substantially as herein described with reference to any one of the embodiments shown in the accompanying drawings.

14. An apparatus for sorting objects on the basis of their weight substantially as described herein with reference to any one of the embodiments shown in the accompanying drawings.