CA1130892A - Apparatus for optically sorting articles - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
Optical sorting apparatus wherein during sorting, articles are directed to free fall through an illuminated inspection chamber. A light reflecting background posi-tioned in the chamber is adjustable to form a variable reference standard of reflectivity. A sensor positioned to receive light from the background establishes a reference level and also receives reflected light from objects passing through the chamber. A change in detected light level from the reference level is indicative of a property of an article to be sorted for selectively effecting sortation of the article.

Description

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1 BACKGROUND OF THE INVENTIO_ Ihis invention relates to the sortation of articles such as food products in accordance with the color of the product as compared to a reference standard while the article free falls through an illuminated inspection cham-ber.
The typical prior art color sorting apparatus util-izes a reference or background of predetermined reflectivity arranged in the same plane as a sensor which measures reflec-ted light from both the background and the articles passing through the sorting apparatus. The reference level at which sortationtakes place is determined by a comparison of light reflected from the article to the light reflected from the reference or background. When no product is in the optical plane of the sensor, the electrical condition of the sensor is returned to the level determined by the reference and all objects being sorted are measured from that level. Typically, a reference level is chosen from which desirable objects produce either no change or a change in condition of the circuitry opposite to the change produced by an undesirable object. As the color or reflectivity of the objects being sorted changes, it is quite often necessary to change the reference level to maintain the proper balance for correct sorting. Typically, this is done by replacing a reference background with a background of appropriate color or reflec-tivity for the objects being sorted. This method has the disadvantage, however, of requiring the selective use of several of the various references which are colored in steps or ranges. Further, the changing of the reference requires significant effort and time during which the sorting appar-atus is not operating.

-2-1130t5 92 1 In another system for varying the reference level, the reference background may be moved toward or away from the light source so that the intensity of the light re-flected from the background varies. Since light energy decreases as the square of the distance from ~he background, the system is not linear and therefore it is difficult to establish the proper reference level before effective sorting operations can commence.
Another approach known in the prior art is to vary the angle of the reference with respect to the plane of the sensor and the light source. This method is difficult to control since the position of the light source and the surface characteristics of the reference cause irregular nonlinear changes in the light directed to the sensor.
Further, in such sorting of articles, particularly food objects, the freefall trajectory of the article through the inspection port should be controlled to prevent the object from moving away from a predetermined path. As long as the apparatws is designed for use to inspect a specific product, the trajectory of that object can be planned for in the design of the apparatus. The resultant apparatus there-fore is not conveniently adaptable to objects deviating from the characteristics of the object for which it is designed.
Known prior art apparatus has not permitted convenient ad-justment or control of the trajectory of an object through the inspection port to accommodate wet or dry objects or objects of different physical characteristics which affect their freefall trajectory.
Typically, articles which do not meet the desired standards are removed from the inspection shamber by means of a blast of fluid pressure from a nozzle. In the prior `` 1iL3089~

1 art, a nozzle directs a jet of fluid pressure, such as air, to strike and displace the object from the predetermined path in response to a signal from the detector. The positioning of the nozzle with respect to the path of the article is of extreme importance and if the nozzle and article are not in alignment then the jet of air cannot strike the article and the article will not be rejected.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, a sorting apparatus includes a chamber or inspection port through which articles to be sorted are individually passed and optically sorted. Means are provided for illuminating the chamber and a light reflecting background means is posi-tioned in the chamber to form an adjustable reference standard of reflectivity. The reflecting means includes a first member having spaced segments of different light-reflecting characteristics and a second member positioned over the first having a series of spaced apertures formed therein. The apertures correspond generally to the light absorbing segments formed in the first member and drive means is provided for moving one of the members with respect to the other to adjust the reflectivity of the background surface by selectively exposing the segments through the apertures to establish a predetermined background level. A
detector is positioned to receive light reflected from the background to establish a reference level and to receive light reflected from objects passing through the chamber. A
change in detected light level from the reference level as the article passes is indicative of a property of an article to be sorted for effecting sorting of the article.
The inspection port or chamber has inlet and li30892 :`
l outlet ends through which the articles freely fall in a predetermined path generally along the length of the cham-; ber. Downwardly depending directing means extends between a hopper to receive the articles and the chamber for directing the articles to the inlet end for free fall therethrough along the predetermined path. According to another aspect of the present invention, the directing means and chamber are adjustably mounted to vary the angular relationship with respect to the framework such that the trajectory of articles directed to free fall through the chamber can be adjusted to follow the predetermined path and thus accommodate articles of varying size, weight and surface characteristics.
According to still a further aspect of this inven-tion, an improved nozzle is provided for use in the sorting apparatus whereby the nozzle is selectively employed to eject articles from a stream of articles passing through the chamber. The improved nozzle includes a housing having a chamber formed therein. The inlet portion of the chamber has a relatively deep narrow surface area while an outlet portion thereof tapers outwardly and has a relatively wide, thin surface area. Preferably, the cross-sectional area of the inlet portion is approximately equal to the cross-sectional area of the outlet portion to thereby maintain a constant velocity of air flow therethrough and to provide a wide blast of air at the outlet to thus insure that articles not meeting the standard are effectively removed from the chamber of the inspection port.
The present invention thus improves upon and overcomes the disadvantages of the above-noted prior art devices. Other important advantages and features of the invention will become readily apparent to those skilled in 0~392 1 the art upon reading the following specification and with reference to the accompanying drawings.
- BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a perspective view of the sorting apparatus of the present invention;
Fig. 2 is a side elevation view of the sorting apparatus shown in Fig. l;
- Figs. 2a and 2b are enlarged details of the mounting for the inspection assembly;
Fig. 3 is an enlarged, exploded view of the inspec-tion port, illumination source, detecting means and adjustable reference background member;
Fig. 4 is a partial view showing the bottom portion of the inspection port and nozzle assembly;
Fig. 5 is a cross-sectional view of the inspection port taken generally along the plane V-V of Fig. 4;
Fig. 6 is a perspective rear view o-f the adjust-able reference background members in an assembled rela-tionship;
Fig. 7 is an enlarged, exploded view of the nozzle assembly for selectively rejecting articles from the stream of articles to be sorted;
Fig. 8 is an end view of the assembled nozzle assembly shown in Fig. 7; and Fig. 9 is an electrical circuit and fluid flow diagram in block form of the control circuits for detecting and selectively rejecting objects.
DESCRIPTION OF THE PREFERRED EMBODIMENT
. _ .
Referring now to the drawings and in particular to Figs. 1 and 2, the article sorting apparatus 1~ of the present invention includes a supporting framework 12 upwardly 1 extending from a base 14 which is mounted on casters 16 for portability of this unit. A receiving hopper 18 is posi-tioned at the top of frame 12 to receive a quantity of ~, articles to be sorted typically -from a conveyor. A singu-i 5 lator assembly 20 including a pair of spaced vibratory trays 22 and a suitable vibrator drive 24 is positioned below the outlet end of hopper 18 to receive the articles and to dis-` charge them in single row fashion from the trays 22 into a pair of spaced downwardly depending generally parallel directing means or chutes 26. Chutes 26 are pivotally suspended on the frame 12 by means of hooks 28 extending pivotally over a rod 29 extending transversely between the vertically extending frame members. Adjustment means 30 (described in greater detail below) is provided to adjust the angular relationship of chute 26 with respect to frame 12.
An inspection assembly 32 containing a pair of inspection ports or chambers 34 is removably and pivotally supported at the outlet end of chutes 26 such that articles under inspection will free fall therethrough. Inspection assembly 32 includes a pair of inspection ports 34 (Pig. 3) each containing suitable sensing means for detecting light reflecting properties of articles passing therethrough. A
control panel 36 is positioned near the upper part of frame-work 12 for convenient access. The control panel containing the electronic control circuits is electrically coupled to the inspection assembly 32.
Inspection assembly 32 forms a generally box-like enclosure having an upper wall 42, a lower wall 44, front and rear walls 46 and side walls 48. A pair of spaced generally vertically extending inspection ports 34 are formed within the enclosure to extend between upper wall 42 :
1 and lower wall 44. With reference to Figs. 3-5, one of the identical inspection ports will be described in greater detail. The inspection port includes an elongated annu]ar outer housing 38 and a removable inner housing or sleeve 40.
Sleeve 40 extends between the upper wall 42 and lower wall 44 and is secured therein by a retainer ring 50 positioned in bottom wall 44. O-ring seals 52 positioned on the inner surface of bottom wall 44 seal sleeve 40 with respect to walls 42 and 44. Clamping members 53 secured to the bottom wall extend inwardly toward the center of the chamber to hold the sleeve in place. Screws 54 holding the clamps can be removed so that the sleeve can be removed for service and the like. Sleeve 40 is formed of transparent material, for example, clear plastic and forms a liner for the inspection port to isolate the electrically operated components from the stream of products passing through the port while providing an optical path therethrough.
Illuminating means, preferably a pair of annular fluorescent light tubes 55, are positioned at the upper and lower ends of housing 38 adjacent the inner surfaces of walls 42 and 44 and surround an exposed portion of trans-parent sleeve 40. When energized, the annular light tubes uniformly illuminate the interior of the inspection chamber 34. The transparent sleeve also serves as a light guide dispersing the light from the annular fluorescent tubes to completely illuminate the inspection chamber and articles passing therethrough.
As shown in Fig. 3, an opening 56 is provided in wall 38 at one side of the chamber to receive a detector assembly 58. Directly opposite opening 56 an elongated opening 60 is provided to receive an adjustable light - , ; 1 reference background assembly 62.
With reference to Figs. 5 and 6, the adjustable background assembly 62 includes a first rectangular mem`ber 64 having spaced segments 66 of different light reflecting characteristics formed thereon. Preferably, alternate light reflecting and light absorbing bands are formed thereon.
Each spaced segment 66 may be formed by a stripe of black paint which forms a light absorbing surface painted on the surface of plate member 64 and the alternate spaces 68 between each absorbing band is of a reflecting nature such as white paint. The first member has an outwardly extending tab 70 formed thereon which, as will be hereinafter des-cribed, is adapted for connection to a drive motor 72 for adjustment purposes. A second rectangular member 74 is positioned over the first member and has a series of spaced apart apertures 76 formed therein which correspond generally to the width of each light absorbing band 66 formed on the first member. The face of member 74 facing the detection assembly is black in the preferred embodiment such that the reference background may be adjusted from total black to approximately 50 percent white The first and second members are mounted for sliding movement with respect to one another in a supporting frame which includes a first pair of spacers 78 having tabs 80 formed thereon which3 when assembled with a second pair of spacers 82, form a guideway to slidably receive first member 64. A transverse clamping member 84 and a combined clamp and motor mount 86 are positioned adjacent spacers 82.
Fastening screws 88 are passed through suitable openings in clamp 84, blocks 82 and 78 and into threaded openings 90 formed in the sidewall of outer housing 38 adjacent opening g 1 60. Similarly, clamp and motor mount 86 is provided with suitable openings through which screws 92 extend through mounting blocks 82 and 78 and into corresponding threaded openings (not shown) adjacent opening 60. Clamp and motor mount 86 is also adapted to receive drive motor 72 which is secured thereon in a conventional manner. Shaft 94 of motor 72 includes a threaded portion 96 which extends through and threadably engages tab 70 on first member 64. Motor 72 is electrically connected via suitable lead wires 97 to the electrical circuitry contained in control panel 36. Oper-ation of the motor in a first direction will cause member 64 to move in a first direction with respect to the second member while rotation of the motor in the opposite direction will correspondingly move member 64 in the opposite direc-tion. This will change the relative positions of the alternate light and dark bands 66 and 68 of the first member with respect to the apertures 76 formed in second member 74 causing the surface exposed through opening 60 in the chamber in a shutter-like fashion to reflect more or less light to the detector 58.
Although the face of member 74 is described as black in color to absorb light, the face may be provided with a light reflecting surface, as white, such that adjust-ment may be made with plate member 64 to attain a total white background to approximately 50 percent black. Other colors may be selected to absorb and reflect light as re-quired depending upon the product being sorted. Similarly, transparent plate members having opaque surface areas formed thereon to control the amount of light passing therethrough may also be utilized.
Light detector assembly 58, as previously mentioned, 1 is positioned opposite the reference background surface 62 in housing 38. The detector assembly is of conventional construction and includes a lens and filter 100, detector 101 and suitable mounting means 102 therefor. Mounting means 102 is held in position by screws 104 received in threaded openings 106 adjacent opening 56 in the sidewall of housing 38. Although a single lens and filter 100 is shown, it will be appreciated by those skilled in the art that different filters can be substituted to vary the sensitivity depending upon the color of the object being sorted. The detector is positioned to receive light reflected from background assembly 62 and objects passing through the chamber.
While a single reference background assembly 62 and detector assembly 58 are shown positioned on opposite sides of the inspection chamber, two or preferably three such assemblies may be used in connection with each in-spection chamber. In this case, it is preferable to space them equally, that is, 120 around the diameter of the inspection chamber.
A ring-like nozzle assembly llO is positioned at the uppermost end of the transparent sleeve and includes a fitting 112 for connection to a source of liquid as water or similar cleaning fluid. The ring nozzle assembly 110 includes a plurality of outlet orifices 114 which extend to direct a spray of liquid downwardly along the inner walls of the transparent sleeve 40. Fluid introduced to the ring nozzle assembly, when outletting at orifices 114, will serve to keep the interior walls of the transparent sleeve clean.
An ejection nozzle assembly 116 (Figs. 7 and 8) is positioned adjacent the outlet portion of each inspection 1~30~92 1 port 34 and includes an inlet fitting 118 adapted for connection through suitable electrically actuated valve means 120 (Figs. 4 and 5) to a source of flu:id pressure 122 (Fig. 9). Valve 120 is a conventional solenoid valve and is connected in a line 124-124' (Fig. 9) between the nozzle and a source of fluid pressure 122. Solenoid valve is operated in a conventional manner by means of suitable electronic circuitry contained in control panel 36. The controls include conventional threshold circuit 123 coupled to the detector 98 for receiving electrical signals therefrom and for generating an output control signal at conductor 126 for actuating valve 120 to effect ejection of a defective article from the stream of articles passing through the inspection port. The control circuits 36 are conventional employing commercially available integrated circuits.
As shown in Figs. 7 and 8, ejection nozzle assem-bly 116 comprises a two-piece housing including a cover 130 and a base 132. Base 130 has a chamber 134 formed therein which includes an inlet portion 136 and an outlet portion 138. The inlet portion of the chamber has a relatively narrow, deep surface area located, when assembled, directly below fitting 118 in the cover 130. The chamber tapers outwardly from inlet 136 toward outlet 138. The outlet 138 as viewed in Fig. 8 is seen to be relatively wide and thin.
Preferably, the cross-sectional area of the narrow and deep inlet portion is approximately equal to the cross-sectional area of the wide and thin outlet portion to thereby maintain a constant pressure and flow velocity from the inlet to the outlet of the nozzle assembly. A plurality of screws 140 extend through suitable openings formed in cover 130 and are received in suitable threaded openings 142 spaced around 11~3(~892 1 base 132. Nozzle assembly 116 is secured to bottom wall 44 of the inspection chamber by means of screws 144 (Fig. 4) received in bottom wall 44 of the inspection assembly such that outlet end 138 of the nozzle faces inwardly toward the center of the inspection chamber to direct a blast of fluid pressure over the outlet opening of the inspection port to thus remove undesired articles from the predetermined path.
Screws 140 permit the nozzle to be adjusted toward and away from the inspection port.
As shown in Fig. 4 and in the schematic view of Fig. 9, nozzle 116 is connected via lines 124-124' and valve 120 to the fluid pressure source 122. Preferably, valve 120 is contained within inspection assembly 32 and is opera-tively connected for operation by the circuits in control panel 36. Fluid pressure source 122 which may include a compressor ~not shown) may be contained within a housing 146 supported on framework 12. ~ousing 146 may also contain a suitable source of liquid and associated pressure source to provide the cleaning liquid directed by ring nozzle assembly 110 and orifices 114 over transparent sleeve 40 within the inspection chamber.
With reference again to Figs. 2, 2a and 2b, it will be noted that inspection assembly 32 is secured to the end of the chutes or directing means 26. A pair of bracket members 148 are secured at the ends of the chute 26 to extend generally perpendicular thereto. ~racket members 148 are positioned at each side of the chute 26 and each include a pair of outwardly extending pins 150 and 152 to which a corresponding pair of brackets 154 and 156, respectively, are used to attach the inspection assembly 32 to the end of the chute. Bracket member 154 is formed with an elongated 08g2 l slot 158 having an upwardly extending e]ongated detent portion 160 which engages pin 150. ~racket 156 is formed with a slot 162 having a similar detent portion 164 to receive pin 152. Inspection assembly 32 may be conveniently removed from the chute 26 by lifting it slightly such that detents 160-162 release from the pins 150 and 152 and move outwardly through slots 158 and 162. For cleaning and other maintenance purposes, inspection assembly 32 may be released at only one side at pin 152 and pivoted or hinged downwardly about pin 150. This greatly facilitates access to the interior of the inspection chamber for cleaning and like maintenance operations.
To accommodate articles of varying size or density and to insure the proper trajectory of the articles along the predetermined path through the axis of the inspection chamber, chutes 26 may be adjusted to differing angular relationships with respect to frame 12 through the utili-zation of the previously mentioned adjusting means 30.
Adjusting means 30 includes a pair of outwardly extending arms or brackets 170 pivoted at one end 172 to framework 12 on a mounting bracket 174. A pin 176 extending through mounting bracket 174 pivotally supports the arm 170. An arcuate series of spaced openings 177 positioned along the outermost end of arm 170 match with a corresponding opening formed in the frame supporting chutes 26 such that the angular relationship of chutes 26 with respect to frame 12 may be adjusted to the desirable positon. A pin 178 or other suitable fastening means extending through a selected opening 177 and through the opening provided in the chute fixes the chutes in the desired position. Accordingly, the angular relationship of chutes 26 may be adjusted as required : ~ -1 while maintaining the angular relationship of the inspection assembly to achieve the proper trajectory of the article passing through the inspection port along the predetermined path generally along the axial center line of the inspection chamber.
OPERATION
In operation, a quantity of articles to be sorted such as cherries are fed into the hopper 18 where they are fed and arranged by the singulator assembly 20 into chutes 26 where they are directed to free fall through the inlet end of the inspection port. Prior to beginning the sortation process, a reference threshold level is established by oper-ation of the controls to adjust the surface of the reference background assembly 62. During such adjustment, the control circuits 128 operate motor 72 as required to shift first member 64 with respect to the second member 74 and thus expose more or less of the reflecting surface to the detector assembly 58. The surface reflectivity of the reference back-ground is thus selected to have a light reflecting capability similar to that of the desirable inspected article. This adjustment typically is affected by running the product through the unit and controlling motor 72 until the defective product is ejected from the product stream. As the article free falls through the inspection chamber, the signal de-tected, that is, produced by the article depends on the ability of the object to reflect light. If the article is flawed, that is, if it contains dark spots, for example, the signal detected by the sensor assembly deviates from the established threshold level and the threshold circuit acti-vates valve 120. This, in turn, connects the fluid pressure source 122 to nozzle 116 and the jet of fluid pressure at ~130~392 1 outlet 138 ejects the article from the predetermined path through the inspection chamber. The good articles, in turn, fall onto an output conveyor (not shown) while the defective products can be caught by a container placed under the sorting unit.
The apparatus sorts in accordance with more or less light reflected from the article to be sorted as com-pared to a standard. Articles which reflect a predetermined level of light when compared to the reference have no effect whatsoever on the threshold circuits and thus the object is free to pass through the inspection chamber and into suitable conveying or container means.
When objects having basically the same character-istics but of a different color are to be sorted, compen-sating color filters may be positioned at the detector and corresponding adjustments may be made to the reference back-ground. Similarly, when objects of greater or lesser weight which will not follow the necessary trajectory along the predetermined path through the inspection chamber are sorted, suitable adjustment may be made by pivoting the chute 26 about hook 28 and through the use of adjustment means 30.
Those skilled in the art will thus appreciate that an improved sorting device for optically sorting articles has been provided by the present invention. The invention not only provides an improved apparatus for changing the light reflecting characteristics of the reference background but additionally provides novel means adjustably mounting the directing means or chute and inspection means together for varying their angular relationship with respect to the frame-work so that the trajectory of articles directed to free fall through the inspection chamber will follow the predetermined ' ' . ' ` :

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1 path. Finally, an improved nozzle assembly for selectively ejecting articles from a stream of articles passing through the inspection chamber has also been provided.
While a preferred embodiment of the invention has been illustrated and described, it will be recognized that other embodiments and modifications of this invention incorporating the teachings hereof may be readily made in the light of this disclosure. Such modifications employing the principles of this invention will, however, fall within the scope of the appended claims.

Claims (2)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A sorting apparatus comprising a chamber including open ends through which articles to be sorted are individually passed for optically sorting the articles; means for illuminating said chamber; light reflecting background means positioned on the side of said chamber and forming an adjustable reference standard of reflectivity, said reflecting means including a first member having alternately spaced stripes of different light reflecting characteristics, a second member positioned over said first member and having a series of spaced slots formed therein, said slots corresponding generally to alternate spaced stripes formed on said first member and means for moving one of said first and second members with respect to the other of said members to adjust the reflectivity of said background means by selectively exposing said segments through said apertures to establish a predetermined back-ground level; and detection means positioned on said chamber opposite said background means to receive light reflected from said background means to establish a reference level and including, lens means focussing said detection means on objects passing through said chamber approximately midway between said detection means and said background means whereby a change in detected light level from said reference level is indicative of a property of an article to be sorted for effecting sorting of the article.

2. The sorting apparatus as defined in claim 1, whereby an ejecting nozzle is selectively employed to eject an article from a stream of articles for sorting the articles and wherein said nozzle includes a housing; a chamber formed in said housing, said chamber having an inlet and an outlet, said inlet of said chamber being relatively narrow and deep, said chamber tapering outwardly towards said outlet wherein said outlet is relatively wide and thin and wherein the cross-sectional area of said narrow and deep surface area is approximately equal to the cross-sectional area of said wide and thin area for maintaining a constant pressure and air flow through said nozzle.