US3380586A

US3380586A - Sorting machine with magnetic memory

Info

Publication number: US3380586A
Application number: US496517A
Authority: US
Inventors: Charles W Frobese; Stanley H Van Wambeck
Original assignee: Mandrel Industries Inc
Current assignee: Satake USA Inc; Mandrel Industries Inc
Priority date: 1965-10-15
Filing date: 1965-10-15
Publication date: 1968-04-30
Anticipated expiration: 1985-04-30
Also published as: GB1131889A; DE1481035A1

Description

April 30, 1968 c. w. FROBESE ETAL 3,380,586

SORTING MACHINE WITH MAGNETIC MEMORY 5 Sheets-Sheet 1 Filed Oct. 1-5, 1965 AMPL/F/EZ MA'MOEY 5Y5 TEM MEANS PRODUCT FROM HOPPER CHARLES 14 Feoaass Q STANLEY/v VA/VM/AMBECK INVENTORS II E 477'0E/VEY April 30, 1968 c. w. FROBESE ETAL 3,380,586

SOHTING MACHINE WITH MAGNETIC MEMORY 5 Sheets-Sheet 5 Filed Oct. 15,

kuswmu Nm Gimmes 14 1 20,9556 SIM 45V. lvvl lwsacxc INVENTORS April 1968 0 vv. FROBESE ETAL 3,380,586

SORTING MACHINE WITH MAGNETIC MEMORY Filed Oct 15, 1965 5 Sheets-Sheet 4 I C/meus M4 Emma-55 INVENTORS BY yaw/44 April 30, 1968 c. w. FROBESE ETAL 3,380,586

SORTING MACHINE WITH MAGNETIC MEMORY Filed Oct. 15, 1965 5 Sheets-$heet 5 CHAELEfl M Fe05$ STANLEY A. Mam M14455 INVENTORS United States Patent 3,380,586 SORTING MACHINE WITH MAGNETIC MEMORY Charles W. Frobese and Stanley H. Van Wanrbeclr, Houston, Tex., assignors to Mandrel Industries, Inc., Houston, Tex., a corporation of Michigan Filed Oct. 15, 1965, Ser. No. 496,517 Claims. (Cl. 20974) ABSTRACT OF THE DISCLOSURE Ferrule wheel conveyor sorting machine with magnetic memory for storing reject pulses developed when defective objects are conveyed past a classification station until such time the defective objects arrive at a sorting station whereat the reject pulses are effective to actuate an ejector for delivering the defective objects to a defective object collection point. The memory has a re cording density that is only limited by the number and spacing of the conveyor ferrules and is adapted to use with a wide variety of conveyor wheels having different numbers of ferrules.

This invention relates generally to sorting machines of the type wherein objects are conveyed past an inspection point whereat object classification information is derived and then to a sorting station whereat the objects are separated in accordance with the previously derived classification information. The invention is more particularly directed to a magnetic memory system for sorting machines of this type which receives the classification information when an object is viewed at the inspection point and stores the information until the object is at the sorting station for classified sepration.

Fully automatic sorting machines are well known for rapidly and accurately processing free-flowing objects requiring selection or sorting in order to obtain an accept able product of uniform color. These machines conventionally include a ferrule wheel conveyor which comprises a wheel with a partial vacuum inside and a number of ferrules spaced about the periphery of the wheel to form passageways from the partial vacuum to the atmosphere.

The wheel rotates so as to dip into a bowl containing the product to be sorted with the result that the objects are held to the tips of the ferrules by atmospheric pressure attempting to enter the vacuum wtihin the wheel. In the rotation of the conveyor wheel the ferrules are moved past an inspection station where the conveyed objects are classified by photoelectric comparison of the quantity of light reflected from their surfaces with that reflected from a selected standard, or background. For example, a defective object reflects a significantly different quantity of light than the background with the result that a reject signal is generated. In this case, an acceptable object reflects substantially the same quantity of light as the background such that no reject signal is generated. The ferrules are also moved to a sorting station located at a position following the inspection station in the direction of a conveyor rotation. An ejector operates at the sorting station to release defective objects from the ferrules to a defective product chute, or the like, in response to a reject signal having been previously generated due to the classification action which took place at the inspection station. In the absence of a reject signal a corresponding acceptable object is conveyed beyond the defective product chute to a position adjacent an acceptable product chute Whereat the partial vacuum holding the object on the ferrule is removed to thereby release the object to the chute.

By virtue of the delay between the time an object is classified at the inspection station and the time the same object is at the sorting station, a memory or delay device is required in the sorting machine to correspondingly delay reject signals in their actuation of the ejector. In other words a reject pulse generated in response to a defective object passing the inspection station is stored until such time as the object is conveyed to the sorting station adjacent the defective product chute. The stored pulse is then effective to actuate the ejector to release the defective object to the chute.

Heretofore, the memory devices employed in sorting machines have been variously limited and disadvantageous. Electrostatic memory systems have been employed which have pulse storing capacitors embeded in a commutator. These systems require constant maintenance of wearing parts such as the communtator segments and brushes associated therewith. Moreover, electrostatic memory systems are unsuited to service in wet environments unless completely sealed, thus adding materially to the cost of the memory system. Existing magnetic memory systems are disadvantageous from the standpoint of complexity and attendant high cost and are limited as to their versatility. Such systems include a disc with a plurality of slugs of magnetic material evenly spaced in a circle. The slugs each correspond to a different one of the conveyor ferrules and is aligned therewith. The slugs are activated without actual contact by means of special record, pickup, and erase coils which require high energy to magnetize and erase the slugs. Aside from the energy requirements, the disc and coils are diflicult to manufacture. By virtue of the separate slugs employed for the respective ferrules, the system does not lend itself to high density recording and thus limits the spacing and number of ferrules that may be employed on the conveyor. Furthermore, the slug system is not suited to use with a plurality of conveyors, each having a different number of ferrules Without a corresponding change of the slug disc of the memory system.

It is therefore an object of the present invention to provide an improved sorting machine memory system which overcomes the previously noted limitations and disadvantages of previous electrostatic and magnetic memory systems.

Another object of the invention is the provision of a sorting machine magnetic memory system which is more versatile and less expensive than existing magnetic memory systems.

Still another object of the invention is to provide a sorting machine magnetic memory system having a recording density that is only limited by the number and spacing of the conveyor ferrules.

It is a further object of the invention to provide a magnetic memory system of the class described which is adapted to use with a wide variety of conveyor wheels having different numbers of ferrules.

Additional objects and advantages of the invention will become apparent upon consideration of the following description thereof taken in conjunction with the accompanying drawings, wherein:

FIGURE 1 is a schematic representation of a sorting machine embodying a magnetic memory system in accordance with the invention;

FIGURE 2 is a semi-schematic perspective view illustrating the general principles of the magnetic memory system of the present invention;

FIGURE 3 is a schematic diagram of a preferred form of memory system in accordance with the invention as associated with the classification circuitry of the sorting system;

FIGURE 4 is a sectional view taken in a diametric plane through a preferred structural arrangement of the memory device of the system; and

FIGURE 5 is a sectional view taken at line 5'-5 of FIGURE 4, and with portions broken-away to illustrate internal details of construction.

Referring now to FIGURE 1, a sorting machine 11 is provided which includes a feed bowl 12 rotated as by means of a motor 13 coupled thereto by means of a drive belt 14. A hopper 16 is positioned to direct a product 17 to be sorted, such as beans, nuts, or other objects, upon the feed bowl. The rotating feed bowl operates in a well known manner to centrifugally form a single row of the objects at the outer or transfer edge of the bowl moving at the proper speed for a successful transfer to a nearly tangentially rotating ferrule wheel conveyor 18. Such conveyor includes a hollow disc or wheel 19 having a plurality of ferrules 21 projecting radially outward therefrom at circum'ferentially spaced positions. The ferrules communicate with the hollow interior of the wheel which is evacuated by a pump or the like (not shown) to establish a vacuum therein. The wheel is rotated as by means of a motor 22 acting through a belt drive 23, or the like, to thereby move the ferrules successively into contact with the objects. The vacuum acting through the ferrules is effective to lift the objects from the bowl singly upon the tips of the ferrules. In this manner the objects are held in a single row and at a fixed distance apart as they are conveyed by the wheel through an inspection station 24 to a sorting station 26 for release to defective or

acceptable product chutes

27 and 28 in accordance with classification information derived at the inspection station.

The inspection station 24 includes at least one light source 29 and photocell means 31 mounted within a light housing 32 and arranged in a well known manner to photoelectrically classify the product conveyed therethrough according to their color. In this regard, each object passed through the inspection station is illuminated and viewed :by the photocell means which include filters for selecting one or more predetermined critical hues of the light reflected from the object. The photocell means measures the reflectivity of each critical hue and transmits a proportional signal to sensing means 33. The sensing means electronically compares the reflectivity signal to a selected reflectivity standard or background. In response to the reflectivity signal being, for example, greater than the background, to indicate a defective object, the sensing means applies a reject pulse to a memory system 34. An acceptable object produces a reflectivity signal which is equal to or less than the background and results in no pulse being applied from the sensing means to the memory system. Alternatively, the sensing means may be arranged such that a defective object is indicated by a retiectivity signal less than the background, in which case a reject pulse is responsively generated while no pulse is produced for reflectivity signals equal to or greater than background. It will also be appreciated that classification means other than photoelectric, e.g., nuclear radiant energy detection means, may be employed at the inspection station in conjunction with the sensing means 33 to supply pulses to the memory in accordance with the classification of the product.

The memory system 34 stores the reject pulses until such time as the objects which effected generation of the pulses are conveyed to the sorting station 26 adjacent the defective product chute 27. At this time, a ferrule carrying a defective object is aligned with an ejector mechanism 36 mounted in fixed position within the wheel and adjacent to which the wheel periphery passes in close proximity. The ejector mechanism may, for example, include an ejection nozzle 37 having a pressurized air hose 38 coupled thereto through a normally closed solenoid actuated valve 39. The nozzle is radially disposed adjacent the inner wheel periphery for successive communication with the ferrules as they are rotated adjacent the defective product chute 27. The solenoid actuated valve, or other actuating means of the ejector mechanism, is coupled to the memory system 34 through, for example,

Cit

.4 an ejector driver 41, and is energized by the stored reject pulse read out of the memory when the ferrule carrying the defective object which previously effected generation of the pulse is in communication with the nozzle. The valve 39 is opened in response to the read out pulse and pressurized air is thus directed from the nozzle through the communicating ferrule to blow the defective object from its tip into the chute 27, as indicated by the trajectory 42. When an acceptable object is adjacent the ejector mechanism, no pulse is read out of the memory since no pulse was generated for storage by the memory when the acceptable object was conveyed past the inspection station 24. The valve 39 is hence not energized and remains closed while the ferrule moves past the nozzle. As a result, the acceptable object is held on the tip of the ferrule as it is conveyed past the defective product chute. It will be thus appreciated that the basic function of the memory is to store reject pulses generated in response to defective objects passing the inspection station until these defective objects are moved adjacent the defective product chute, and at these times to read out the pulses for actuation of the ejector mechanism.

The acceptable objects moved past the defective Product chute are next moved adjacent the acceptable product chute 28. The ferrule is here aligned with a nozzle 43 of a stationary cut-off shoe 44 mounted within the wheel and resiliently urged, as by means of a spring 46, against the inner periphery of the wheel. A continuous low pressure air hose 47 is connected to the nozzle 43. The shoe cuts off the vacuum in the ferrules to thus cause separation of the acceptable objects therefrom. The low pressure air issuing from nozzle 43 enhances the separation process by preventing the objects from sticking to the ferrule tips after the vacuum is cut off. More particularly, some objects tend to stick to the ferrules because they are sticky or because they seal the ends of the ferrules and prevent air from getting into the ferrules to overcome the vacuum. The low pressure air from nozzle 43 prevents this from happening. With the vacuum in the ferrules thus overcome, the acceptable objects carried on the tips of the ferrules are directed into the acceptable product chute 28, as indicated by the trajectory 48. In other words, the acceptable objects are not ejected by the ejector mechanism 36 and are carried past the defective product chute 27 for delivery to the acceptable product chute 28 by the shoe 44 cutting off the vacuum in the ferrules and the air continuously issuing from nozzle 43 entering the ferrules. The shoe 44 may also be provided with a nozzle 49 to which a high pressure air hose 51 is connected to purge the empty ferrules as they move by prior to picking up another object from the feed howl 12.

The sorting machine 11 described to this point is conventional and well known to the present state of the art. However, the magnetic memory system 34 in accordance with the present invention employed in the sorting machine 11 is variously advantageous over memory systems that have been previously utilized. As is schematically depicted in FIGURE 2, the memory system 34 is relatively simple in that the rincipal elements of the system are a magnetic recording drum 52 and at least one magnetic reference pulse generator drum 53 mounted on a common shaft 54. This shaft may be the shaft of the conveyor wheel 18, as shown in FIGURE 2, or more partically the shaft may be coupled to the conveyor wheel shaft by gears, timing belts, or other non-slip coupling means 5-6 having an integral ratio, as shown in FIGURE 3. For purposes of understanding the basic concept of the memory system, a one to one relationship, as provided in FIGURE 2, is for the present assumed.

The memory drum 52 is provided with an outer peripheral surface of a high level magnetic recording medium and non contact record heads 57 and 58 are mounted adjacent the peripheral surface with running clearance. These heads have the same angular spacing as that between

viewing positions

59 and 61 of inspection station 24, where more than one viewing position is employed. A

non contact pickup head 62 is also provided adjacent the drum periphery with running clearance therebetween. The pickup head is positioned with the same angular displacement from the last record head 58 as that existing between the last viewing position 61 and the ejector mechanism 36. In addition, an erase permanent magnet 63 is disposed adjacent the drum periphery at a location between the pickup head 62 and first record head 57.

The reference pulse generator drum 53 is of soft iron, permanent magnetic material, or the like, and the peripheral surface thereof is notched or grooved, as in dicated at 64, at intervals corresponding to the angular spacing between the ferrules 21 of the conveyor wheel 19. In its preferred form, the reference drum resembles a spur gear. A pair of non contact pickup heads 66 and 67 are disposed adjacent the periphery of the reference drum with free running clearance there'be-tween, and such heads have the same angular displacement as that between the memory drum record heads 57 and 58, and

therefore between the

viewing position

59 and 61 of the inspection station 24. By virtue of the notched periphery of the reference drum, a magnetic field variation produced as the drum rotates pass the pickup heads 66 and 67. The field variations have the same spacing as the conveyor ferrules, and a series of electrical reference pulses is induced in each pickup head corresponding to movement of the ferrules ast a given reference point adjacent the conveyor wheel, namely the viewing position 59 in the case of pulses generated by head 66 and viewing position 61 in the case of pulses generated by head 67. The heads, moreover, are so positioned relative to the viewing positions that the pulses are coincident with the mid points between ferrules being observed at the viewing positions.

The photoelectric outputs of the viewing positions 59 and 61 of the inspection station 24 are coupled to

amplifiers

68 and 69 of the sensing means 33, in turn connected to

voltage detectors

71 and 72 thereof. The pickup heads 66 and 67 associated with the reference drum 53 are coupled to the

voltage detectors

71 and 72, preferably via amplifier and

shaper circuits

73 and 74. The outputs of the voltage detectors arecoupled to the record heads 57 and 58 associated with the memory drum 52, while the pickup head 62 is coupled to the ejector mechanism 36, preferably via the ejector driver 41.

With the memory system 34 thus provided and associated with the sensing means 33 and ejector mechanism 36, an object conveyed by the ferrule wheel to the viewing position 59 of the inspection station 33, is viewed by the photoelectric means thereat. The output of the photoelectric means is amplified by amplifier 68 and applied to the voltage detector 71. If the voltage detector classifies the object as defective, coincidently with the occurrence of the next succeeding reference pulse applied to the detector from the pickup head 66 associated with the reference pulse generator drum 53, current is applied to the record head 57 for a predetermined interval. The current flowing through the record head during this interval magnetizes the underlying region of the peripheral surface of the memory drum 52 moving past the head. In this manner, the recorded reject pulses always coincide with a midpoint between ferrules being adjacent the viewing position 59.

The object is then conveyed to the viewing position 61 in those instances where a second classification decision is required. The operation of the amplifier 69, voltage detector 72, reference .pulse head 67, amplifier 74 and memory record head 58 is the same as that described relative to viewing position 59 in recording a signal on the drum in response to a detected defect. By virtue of the angular spacing between the record heads 57 and 58 corresponding to that between the viewing positions 59 and 61, and reject pulses in both instances coinciding with reference pulses immediately following defective classification of objects at the viewing positions,

a reject pulse recorded on the drum by head 58 for a defective object at viewing position 61 coincides with a reject pulse previously recorded on the drum by head 57 due to the same object being classified as defective at viewing position 59. Either or both vie-wing positions may serve to classify the object as defective. If required, the conveyor wheel moves the object through other viewing positions (not shown) to a position adjacent the ejector mechanism 36 at the sorting station 26. At this time, a reject pulse recorded on the memory drum when the object was at the inspection station 24 is beneath the pickup head 62. The pickup head reads out the recorded reject pulse and applies same to the ejector driver 41 which appropriately shape-s the pulse for application to the ejector. The ejector mechanism is thus actuated at the instant the defective object is adjacent the nozzle thereof. The defective object is thus directed into the defective product chute 27.

In the absence of reject pulses recorded on the memory drum 52, the corresponding ferrules 21 of the conveyor wheel move the acceptable objects undisturbed past the ejector mechanism. All of the acceptable objects are thus moved adjacent the shoe 44 and nozzle 43 whereat they are removed to the acceptable product chute 28 in the manner previously described. Thereafter the empty ferrules are moved into the feed bowl 12 to pickup more objects to be sorted. During this time the memory drum passes the erase magnet 63 which resaturates the magnetic medium in the original direction, thus erasing the recorded reject pulses.

The magnetic memory system 34 generally described hereinbefore may be readily adapted to accommodate a variety of different ferrule wheel conveyor geometries, i.e., conveyor wheels with varied numbers of ferrules and ferrule spacings. Basically, as will be described more fully hereinafter, this is accomplished by providing a plurality of the reference pulse generating drums 53 on the shaft 54, and counters to divide the number of pulses per revolution. A pair of reference drums, each arranged to produce different numbers of magnetic field variations per revolution, together with a simple divider and switching arrangement can be employed to produce reference pulses suitable for use with a wide variety of conveyor wheels.

Considering now a preferred embodiment of memory system 34 in accordance with the invention arranged in the manner briefly outlined above for versatility of operation, reference is made to FIGURE 3 wherein the system is shown in association with a preferred arrangement of the classification and sensing means 33. The memory system 34 includes an additional reference pulse generator drum 53 and this drum together with reference pulse generator drum 53 and memory drum 52 are all mounted on common shaft 54 which is coupled to the drive shaft 76 of the conveyor wheel 19 by the coupling means 56 which has an integral ratio of, for example, 3 to 1. In the illustrated case the motor 22 is coupled in driving relation to the shaft 54 which in turn drives the shaft 76 through the coupling means. The motor may, of course, be alternatively coupled to the shaft 76. In either case, with the specific ratio noted above, the memory shaft 54 rotates at three times the rate of the conveyor wheel shaft 76. The reference pulse generator drums 53 and 53' preferably each have different numbers of teeth, for example, drum 53 advantageously has 40 teeth while drurn 53' has 60 teeth. Therefore, when referenced to the conveyor wheel 19, the pickup heads 66 and 67 adjacent reference drum 53 generate pulses per revolution, and the pickup heads 66' and 67 associated with the reference drum 53' generate pulses per revolution, of the conveyor wheel. Thus, the reference drums provide reference pulses which are directly usable with 120 and 180 ferrule conveyor wheels.

In order that the two reference drums 53 and 53' provide a plurality of additional numbers of pulses per revolution, a pair of multi position selector switches 77 and 78 are provided to couple the pickup heads associated with the drums to a selectable ratio binary divider circuit generally designated at 79. In the illustrated case, the switches have six positions designated as 16. Alternate positions 1, 3, and 5 of switch 77 are jumpered together and connected to pickup head 66' associated with the 180 pulse per revolution reference drum 53' while positions 2, 4 and 6 are jumpered together and connected to pickup head 66 associated with the 120 pulse per revolution reference drum 53. Similarly, alternate positions 1, 3, and S of switch 78 are jumpered together and connected to pickup head 67' while positions 2, 4, and 6 are jumpered together and connected to pickup head 67. The

selectors

81 and 82 of

switches

77 and 78 respectively are connected to inputs of the previously mentioned amplifier and

shaper circuits

73 and 74, the outputs of which are coupled to one-half counters 86 and 87 of the binary divider circuit 79. The outputs of these counters are coupled to one-

fourth counters

88 and 89. Multi position selector switches 91 and 92 are provided with positions corresponding to those of

switches

77 and 78. Consecutive pairs of the positions of switches 91 and 92 are jumpered together, i.e., positions 1 and 2, 3 and 4, and 5 and 6 are respectively cornmoned. The outputs of amplifier and shaper circuit 73, one-half counter 86, and onefourth counter 88 are respectively connected to the commoned positions 1 and 2, 3 and 4, and S and 6 of switch 91. Similarly, the outputs of amplifier and shaper circuit 74, one-half counter 87, and one-fourth counter 89 are respectively connected to the commoned positions 1 and i2, 3 and 4, and 5 and 6 of switch 92. The

selectors

93 and 94 of switches 91 and 92 and the

selectors

81 and 32 of

switches

77 and 78 are all ganged together for correlated movement between corresponding switch positions. Thus when the switches are all in position 1, switches 77 and 78 couple the 180 pulse per revolution outputs of heads 66' and 67' to amplifier and

shaper circuits

73 and 74 and switches 91 and 92 couple the shaped 180 pulses per revolution outputs thereof to

selectors

93 and 94. Similarly in position 2, the switches provide shaped 120 pulse per revolution outputs at

selectors

93 and 94. In positions 3 and 4 the outputs at

selectors

93 and 94 are derived from the outputs of the one-half counters 86 and 87 such that the pulse rates are half those generated at the pickup heads. Hence, in position 3, the pulse outputs are 90 pulses per revolution, while in position 4 the pulse outputs are 60 pulses per revolution. When the selectors are placed in positions 5 and 6, the outputs are derived from the one-

fourth counters

88 and 89 such that the pulse rates are one-fourth those generated at the pickup heads. In position 5, the pulse outputs from

selectors

93 and 94 are 45 pulses per revolution while in position 6 outputs of 30 pulses per revolution are provided. It will be thus appreciated that reference pulses are provided at rates suitable for use with six different conveyor wheels, namely wheels having 180, 120-, 90, 60, 45, and 30 ferrules. Preferably, the pulses at

selectors

93 and 94 are applied to one-

shot multivibrators

96 and 97 which serve to provide output pulses of uniform width for application to the

voltage detectors

71 and 72 of the sensing means 33.

Considering now the preferred manner of deriving product classification information from the inspection station 24, the viewing positions 59' and 6 1 are provided with pho tocells or photoelectric means 29 and 29', respectively. The previously mentioned amplifiers 6 8 and 69 in- 'clude gain controls 98 and 99 coupled to the photoelectric means 29 and 2-9 to facilitate appropriate adjustment of the gains thereof. The outputs of the photoelectric means are coupled through isolation preamplifiers 101 and .102 to normalizing

capacitors

103 and 104, in turn connected to inputs of push-

pull amplifiers

106 and 107. These amplifiers are respectively provided with opposite polarity outputs, which in FIGURE 3 are labelled DT and LT to designate dark trip and light trip. The DT and LT outputs of amplifier 106 are respectively connected to a pair of terminals of a selector switch 108, while the DT and LT outputs of amplifier 107 are connected to a pair of terminals of a selector switch 109. The selectors 111 and 11 2 of

switches

108 and 109 serve as inputs to the

voltage detectors

71 and 72 which are subsequently described in detail. The junctures between

capacitors

106 and 104 and amplifiers 106 and 10-7 are respectively coupled through normally open normalizer switches 113 and 1 14 to coarse offset adjustable bias controls 116 and 117. Gate inputs of the norm'alizer switches are respectively coupled to the outputs of

shaper amplifiers

118 and 119, the inputs of which are driven by pickup heads 121 and 122 disposed adjacent the periphery of the conveyor wheel 19. The pickup heads 121 and 122 are energized once each revolution of the conveyor wheel as by means of a permanent magnet 123 mounted on the wheel, or its associated shaft 76, in position to sweep past the heads during rotation of the conveyor wheel.

In the operation of the classification portion of the systern, the electrical signals from the photomultipliers 29 and 29', representative of the light reflected from. the objects as they are conveyed past the inspection station 24, are applied to the

preamplifiers

101 and 102. The preamplifier outputs are coupled through the normalizer cap-acitors .103 and 10-4 to the inputs of the

output amplifiers

136 and 107. The input impedances of the output am plifiers are made as high as possible such that in conjunction with the capacitors, large time constant approaching infinity are provided. Once each revolution of the conveyor wheel, the magnet 123 in sweeping past the heads 12 1 and 122 effects the generation of pulses which are shaped by

shaper amplifiers

118 and 119 for application to the normalizer switches 1113 and 114. The resulting shaped gate pulses close the normalizer switches for brief intervals during which the DC bias levels set by the coarse offset controls 116 and 117 are applied to the capacitors. The time constants of the combinations of preampli liers 101, capacitor 103, switch 113 and coarse olfset control 116, and of preamplifier 102, capacitor 10 4, switch 114, and coarse otfset control 117, are made sufiiciently short that within the durations of the gate pulses, the capacitors assume suitable DC levels for which desired DC levels just below the threshold levels of the

voltage detectors

71 and 72 are established at the output of

amplifiers

106 and 107. -In this manner, drift in the system is compensated. This drift is not only due to drift in the electronic components of the

amplifiers

68 and 69 and in the photoelectric means 2 9 and 29', but is also due to changes in the level of illumination falling upon the objeots at the inspection station 24. The latter form of drift is most troublesome because the objects are conveyed through the viewing positions 59 and 61, and thus debris from the objects is continually contaminating the reflect- I ing walls of the viewing housings associated therewith,

causing the level Oif illumination to fluctuate during a run of the sorting machine. Since a fixed DC level at the inputs of

amplifiers

106 and 107 is re-established once each revolution of the conveyor wheel, the drift is compensated.

Considering now the voltage detectors 7'1 and 72 in greater detail, it will be noted that same preferably include set threshold bistable trigger circuits .118 and 1'19 or" a type which flip from one state to another in response to input signals in excess of a set threshold, and remain in the second state until flipped to the first state by a reset pulse. More particularly, fine offset threshold controls 121 and 1 22 are coupled to the

trigger circuits

113 and 119 to set the triggering thresholds thereof. Set inputs of the trigger circuits 1'18 and 119 are connected in receiving relation to the selectors 111 and 11-2 of switches 108 and 10 9. The trigger circuits are each provided with reset (R) and set (S) outputs, the former of which are unterminated. The set outputs are connected to first inputs of AND-

gates

123 and 124 having second inputs coupled to the outputs of multivi brators 96 and 97. The outputs of gates 1'23 and 124 are coupled to record amplifiers 126 and 127 in turn coupled to the record heads 57 and 58 associated with the memory drum 52. The outputs of the record amplifiers are also coupled by means of

differentiators

128 and 129 to reset inputs of the trigger circuits L118 and 119.

With the selectors 111 and 112 of the

switches

108 and 109 in the dark trip (DT) positions, dark defect objects (i.e., objects which are darker than an acceptable lightly colored object or objects having dark spots on a normal lightly colored background) result in the establishment of peaks in the classification signals fed from the outputs of

amplifiers

106 and 107 to the set inputs of

trigger circuits

118 and 119. Conversely, with the

switches

108 and 109 set in the light trip (LT) positions, light defect objects (i.e., objects which are lighter than an acceptable darkly colored object or objects having light spots on a normal darkly colored background) produce peaks in the classificationsignals fed from the outputs of

amplifiers

106 and 107 to the set inputs of the trigger circuits. In either case, a peak corresponding to a defective object is of sufficient magnitude to exceed the threshold levels preset by the fine offset controls 121 and 122. The trigger circuits are in turn flipped to their set states to produce signals at their set (S) outputs, thus energizing the first inputs of

gates

123 and 124. In response to the next reference pulses from the selector switches 91 and 92 associated with the se lectable reference pulse rate portion of the system, the

multivibrators

96 and 97 are triggered to thereby apply pulses of fixed durations to the second inputs of

gates

123 and 124. Pulses having such fixed durations are thus applied from the gate outputs to the record amplifiers 126 and 127 which in turn apply the pulses to the record heads 57 and 58. The record heads record reject pulses on the drum 52 in the manner described previously. It is of importance to note that inasmuch as the reject pulses are initiated by reference pulses which coincide with the midpoints between ferrules of the conveyor wheel 19, the start of the recording of each reject pulse coincides with such a midpoint irrespective of the position between ferrules at which the defect was detected at the inspection station 24. The outputs of

differentiators

128 and 129 are series of alternately opposite polarity spikes respectively coinciding with the leading and trailing edges of the output pulses from amplifiers 126 and 127. The circuit is arranged such that the spikes corresponding to the trailing edges reset the

trigger circuits

118 and 119, thereby terminating the signals at the set outputs thereof, coincidently with termination of the recorded pulse. Thus, the particular arrangement of the

voltage detectors

71 and 72 just described is such that they function not only as threshold devices, but also as storage elements to hold the information until it has been read into the drum 52.

The reject pulses recorded on the memory drum are read out by the pickup head 62 when the corresponding defective objects are adjacent the ejector mechanism 26, as previously noted. The pulses are applied from the pickup head to the ejector driver 41 which preferably includes an amplifier and shaper 131, driving a one-shot multivibrator 132. The time constant circuit of the multivibrator includes a variable resistance 133 coupled by means of a selector switch 134 in series with a pair of

parallel capacitors

136 and 137. More particularly, the switch is provided with six positions corresponding to those of selector switches 77, 78, 91 and 92, and a selector 138 ganged with the selector of such switches for correlated movement. Positions 1-3 of switch 134 are jumpered and connected to one capacitor 136, while positions 4-6 are jumpered and connected to the other capacitor 137. Thus, when the switches are in any of positions 1-3 (positions for 180, 120, and 90 reference pulses per revolution of the conveyor wheel in the illustrative example) the capacitor 136 and variable resistance 133 determine the time constant, and therefore the duration of output pulses generated by the multivibrator in response to pulses read out of the memory drum by the pickup head 62. Similarly, for any of positions 4-6 (positions for 60, 45 and 30 reference pulses per revolution of the conveyor wheel in the illustrative example) the capacitor 137 and variable resistance 133 determine the duration of the multivibrator output pulses. The

multivibrator pulses are applied by means of a drive amplifier 139 to the actuating input of the ejector mech anism 36 to actuate same for the duration of the pulses. It will be thus appreciated that by providing different values of capacitance for the

capacitors

136, and 137, a different range of pulse durations is provided for the relatively high reference pulse rates (180, 120, and pulses per revolution) than is provided for the relatively low reference pulse rates (60, 45, and 30 pulses per revolution). Furthermore, within each range, the pulse durations may be varied by means of variable resistance 133. This is of importance in that the different pulse rates are used with conveyor wheels having different numbers of ferrules respectively corresponding to the different pulse rates. The ejector mechanism must remain actuated for dwell times which are dependent on the different numbers of ferrules on the respective wheels. In this regard, the fewer the number of ferrules on a conveyor wheel, the greater is the internal diameter of the ferrules and the longer the time required for a ferrule to pass the ejector nozzle at a given conveyor wheel speed. For example, a ferrule conveyor wheel requires the ejector mechanism to be actuated for a period of time corresponding to the time required for 1% degrees of wheel rotation, whereas a 30 ferrule wheel requires a period of time corresponding to 5 to 6 degrees rotation. Thus, the capacitor 136 is selected to be substantially smaller than the capacitor 137 such that a range of relatively short time durations are obtained for the large number ferrule wheel positions of the selector switches while a range of relatively long time durations are obtained for the small number ferrule wheel positions thereof. In this manner, the dwell time of the ejector mechanism may be precisely set to the appropriate value to accommodate whatever ferrule wheel is employed.

It will be appreciated that if any stray pulses get into the

counters

86, 87, 88, 09, their states would be changed resulting in mis-timing of the recorded memory pulses and actuation of the ejector mechanism. Mis-timed operation would then continue until the sorting machine was restarted, or an appropriate sequence of additional stray pulses fortuitously occurs to reset the counters to their proper states. The foregoing difficulties are advantageously overcome in the circuit of FIGURE 3, by connection of outputs of amplifier and

shaper circuits

118 and 119 respectively to reset

inputs

141 and 142 of counters 86 and S8 and reset

inputs

143 and 144 of

counters

87 and 89. As a result, once each revolution of the conveyor wheel 19, as the magnet 123 sweeps past the heads 121 and 122, the amplifier and

shaper circuits

118 and 119 apply reset pulses to

counters

86, 88 and 87, 89 to reset same to their appropriate initial states. Thus, if any malfunction has occurred to cause the counters to slip or pickup an extra pulse, the machine will be out of time for only the remainder of the revolution in which the malfunction occurred.

FIGURES 4 and 5 illustrate a preferred structural arrangement of the mechanical portion of the memory system 34. In this regard there is provided a cylindrical housing 146 having an interior transverse annular plate 147, spider, or the like supporting a bushing 148 coaxially of the housing.

Bearings

149 and 151 retained within the opposite ends of the bushing journal the shaft 54 for rotation coaxially of the housing. The opposite ends of the shaft extend through

dynamic dust seals

152 and 153 carried by

end plates

154 and 156 secured in closing relation to the opposite ends of the housing. The reference

pulse generating wheels

53 and 53 are provided in the forms of spur gears of magnetic material and are coaxially secured to the shaft 54 in the region thereof disposed between the bushing 148 and end plate 154. Preferably one wheel 53 is provided with a collar 157 and the other wheel 53' is secured to the end face of the collar as by means of bolts 158. The collar thus serves to space the wheels 53 and 53' coaxially apart in fixed relation. In addition, a set screw 159 extending radially through the collar and engaging the shaft may be advantageously employed to secure the entire wheel assembly to the shaft in any desired angular relation thereto. The pickup heads 66 and 67, with appropriate angular displacement as discussed hereinoefore, are carried adjacent the periphery of wheel 53 by a bracket 161 secured to the plate 147. Similarly, the pickup heads 66 and 67' with appropriate angular displacement are carried adjacent the periphery of wheel 53' by a bracket 162 secured to the plate 147. Preferably, heads 66 and 67 are respectively diametrically opposed to heads 66 and 67' for the purpose of optimum space utilization.

The memory drum 52 is coaxially secured to the shaft 54 in the region thereof disposed between the bushing 148 and end plate 156. In this regard, the drum is advantageously provided with a collar 163 through which a set screw 164 extends radially into engagement with the shaft. The record heads 57 and 58 with appropriate angula-r displacement as previously discussed are carried adjacent the peripheral surface of the drum by an arcuate bracket 165 secured to the inner periphery of the housing 146. The erase magnet 63 is likewise carried at an appropriate position adjacent the drum periphery by means of a bracket 167. The pickup head 62 is mounted adjacent the drum periphery for selective angular displacement relative to the record heads 57 and 58. This facilitates precise positioning of the pickup head to establish the required angular displacement from the record heads discussed hereinbefore. More particularly, an annular collar 168 is mounted upon the bushing 148 for rotation coaxially thereabout. A radial ear 169 projects from the collar and carries a longitudinally projecting bracket 171 to which the pickup head 62 is secured in close adjacent relation to the drum periphery. Selective angular displacement of the pickup head is preferably facilitated by means of a differentially threaded jack screw assembly 172 coupled to the ear to selectively effect precise angular displacement of the collar. More particularly, the assembly includes a rod 173 formed at one end with an enlarged clevis 174 pivotally connected to the ear in angular relation thereto. The opposite end of the rod is externally threaded, as indicated at 176, for threaded engagement with an internally threaded axial bore 177 of an adjusting bolt 178. The external threads 179 of the bolt engage an internally threaded socket 181 provided in the peripheral wall of the housing 146, the rod extending freely through an aperture 182 in the base of the socket. A spring 183 is coaxially disposed about the rod and acts between the clevis 174 and inner periphery of the housing. The

threads

176 and 177 are relatively fine while the threads 179 and 181 are relatively coarse whereby upon rotation of the bolt 178 a differentially threaded precisely adjustable translation of the rod is effected. Precise rotation of the collar and variation of the angular position of the pickup head 62 relative to the record heads 57 and 58 is in turn effected. The angular spacing between the last record head 58 and pickup head 62 may thus be precisely set to correspond to the angular spacing between the start of the last viewing position of inspection station 24 and the ejector mechanism. 2

Although the invention has been described hereinbefore with respect to several specific embodiments thereof, it will be appreciated that various changes and modifications may be made therein without departing from the true spirit and scope of the invention, and thus it is not fit) intended to limit the invention except by the terms of the appended claims.

What is claimed is:

1. In a sorting machine of the type including a ferrule wheel conveyor for carrying objects to be sorted along an arcuate path, an inspection station disposed in said path having classification means for generating an electrical pulse in response to a defective object carried by said conveyor being disposed at said inspection station, a sorting station disposed in said path having ejection means angularly displaced from the inspection station in the direction of conveyor rotation for ejecting objects from said conveyor in response to reject pulses applied to the ejection means, and means at said sorting station displaced from said ejection means in the direction of conveyor rotation for releasing objects from said conveyor that have passed said ejection means, magnetic memory system comprising a magnetic memory drum having a magnetic recording medium on the peripheral surface thereof, at least one reference pulse generating drum for producing upon rotation magnetic field variations having a predetermined spatial relationship to the ferrules of said conveyor, means coupling said memory drum and said pulse generating drum in common for rotation with said conveyor, at least one memory record head disposed adjacent the periphery of said memory drum, at least one reference pulse pickup head disposed adjacent the periphery of said reference pulse generator drum for generating reference pulses in response to said magnetic field variations, selectable ratio divider means coupled to each reference pulse head for supplying said reference pulses therefrom at different selectable pulse rates, sensing means coupled to said divider means and to said classification means for generating reject pulses in response to coincidences of pulses therefrom, said sensing means coupled to said record head to effect recording of said reject pulses on said memory drum, a memory pickup head disposed adjacent the periphery of said memory drum with an angular displacement in the direction of drum rotation from the last memory record head corresponding to that of said ejection means from said inspection station, said memory pickup head coupled to said ejection means to apply reject pulses thereto read from said memory drum, and magnetic erase means disposed adjacent said memory drum at a position between said memory pickup head and first memory record head in the direction of drum rotation.

2. A magnetic memory system for a ferrule wheel conveyor sorting machine including an inspection station disposed to be adjacent a ferrule wheel of the conveyor and having sensing means for generating reject pulses in response to coincidences between reference pulses and detections of defective object conveyed through said inspection station, and an ejection mechanism disposed with a predetermined angular displacement from said inspection station for releasing objects from the ferrule wheel in response to reject pulses applied thereto, comprising a shaft for coupling to said ferrule wheel, a memory drum mounted upon said shaft and having a magnetic recording medium on its peripheral surface, a plurality of reference pulse generating drums of magnetic material mounted on said shaft and respectively havin different numbers of notches in the peripheries thereof, a plurality of reference pulse pickup heads respectively disposed adjacent the peripheries of said pulse generating drums to generate reference pulses at rates dependent on the numbers of notches therein, a plurality of series connected binary counters, switch means for selectively connecting said pickup heads to the input of the first of said counters, switch means for selectively coupling the outputs of said counters to said sensing means to supply reference pulses at different rates thereto, a memory record head disposed adjacent the periphery of said memory dr-um, said record head connected to the output of said sensing means to record said reject pulses on said memory drum, a memory pickup head disposed adjacent the periphery of said memory drum at a position of angular displacement from said record head corresponding to that between said inspection station and said ejection mechanism, said memory pickup head coupled to said ejection mechanism, and an erase magnet disposed adjacent the periphery of said memory drum at a position displaced from said memory pickup head in the direction of memory drum rotation and between said memory drum pickup and record heads.

3. A magnetic memory system according to claim 2, further defined by a second inspection station preceding the first inspection by a predetermined angular displacement and having second sensing means for generating reject pulses in response to coincidences between reference pulses and detections of defective objects conveyed through said second inspection station, a second plurality of reference pulse pickup heads respectively disposed adjacent the peripheries of said pulse generating drums at positions of angular displacement from said first plurality of reference pulse pickup heads in directions opposing rotation of the reference pulse drums corresponding to the angular displacement between said first and second inspection stations, a second plurality of series connected binary counters, switch means for selectively connecting said second plurality of reference pulse pickup heads to the input of the first of said second plurality of counters, switch means for selectively coupling the outputs of said second plurality of counters to said second sensing means to supply reference pulses at different rates ther to, and a second memory record head disposed adjacent the periphery of said memory drum at a position of angular displacement from said first memory record head in a direction opposing rotation of said memory drum corresponding to the angular displacement between said first and second inspection stations, said second memory record head coupled to the output of said second sensing means.

4. A magnetic memory system according to claim 2, further defined by a cylindrical housing having support means supporting a bushing coaxially thereof, bearing means within said bushing journalling said shaft for rotation coaxially of said housing, said memory drum and reference pulse generating drums upon said shaft being disposed within said housing, means mounting said reference pulse pickup heads within said housing in fixed positions adjacent the peripheries of said reference pulse generating drums, means mounting said memory record head within said housing in fixed position adjacent the periphery of said memory drum, means mounting said erase magnet within said housing in fixed position adjacent the periphery of said memory drum, means mounting said memory pickup head within said housing adjacent the periphery of said memory drum for selective movement angularly thereof relative to said memory record head, and closure means at the ends of said housing traversed by said shaft.

5. A sorting machine comprising a hollow rotatable conveyor wheel having a plurality of circumferentially spaced ferrules projecting therefrom and communicating with the interior thereof, means establishing a vacuum in the interior of said wheel, means coupled to said wheel for rotating same, a feed bowl carrying objects to be sorted disposed adjacent said wheel for successive traversal by said ferrules with said objects being individually picked up and retained on the tips of said ferrules 'by said vacuum, an inspection station disposed adjacent said conveyor wheel, photoelectric means at said inspection station viewing said objects successively conveyed thereto on the tips of said ferrules and generating an electrical signal proportional to light reflected therefrom, an ejection mechanism angularly displaced from said inspection station for releasing objects from said ferrules in response to signals applied thereto, a memory drum coupled to said conveyor wheel for rotation therewith and having a magnetic recording medium on its peripheral surface, a reference pulse generating drum of magnetic material mounted for rotation with said memory drum and having a plurality of notches in the periphery thereof with a predetermined spatial relation to said ferrules, a reference pulse pickup head disposed adjacent the periphery of said pulse generating drum to generate reference pulses at rates dependent on the number of notches therein, a bistable trigger circuit having set and reset inputs and set and reset outputs, means establishing a threshold triggering level at said set input of said trigger circuit whereby same is triggered to energize said set output in response to a signal at said set input in excess of said threshold triggering level, means coupling the signal from said photoelectric means to said set input of said trigger circuit, an AND-gate having first and second inputs respectively coupled to the set output of said trigger circuit and to said reference pulse pickup head and having an output, a memory record head disposed adjacent the periphery of said memory drum, means coupling the output of said gate to said record head, differentiating means coupled to said last named means to generate reset pulses in correspondence with portions of the output signal from said gate, said differentiating means coupled to said reset input of said trigger circuit, a memory pickup head disposed adjacent the periphery of said memory drum at a position of angular displacement from said record head corresponding to that between said inspection station and ejection mechanism, means coupling said memory pickup head to said ejection mechanism, and an erase magnet disposed adjacent the periphery of said memory drum at a position displaced from said memory pickup head in the direction of memory drum rotation and between said memory drum pickup and record heads.

6. A sorting machine comprising a hollow, rotatable conveyor wheel having a plurality of circumferentially spaced ferrules projecting therefrom and communicating with the interior thereof, means establishing a vacuum in the interior of said wheel, means coupled to said wheel for rotating same, a feed bowl carrying objects to be sorted disposed adjacent said wheel for successive traversal by said ferrules with said objects being individually picked up and retained on the tips of said ferrules by said vacuum, an inspection station disposed adjacent said conveyor wheel, photoelectric means at said inspection station viewing said objects successively conveyed thereto on the tips of said ferrules and generating an electrical signal proportional to light reflected therefrom, an ejection mechanism angularly displaced from said inspection station for releasing objects from said ferrules in response to signals applied thereto, a memory drum coupled to said conveyor wheel for rotation therewith and having a magnetic recording medium on its peripheral surface, a plurality of reference pulse generating drums of magnetic material mounted for rotation with said memory drum and respectively having different numbers of circumferentially spaced notches in the peripheries thereof, a plurality of reference pulse pickup heads respectively disposed adjacent the peripheries of said pulse generating drums to generate reference pulses at rates dependent on the numbers of notches therein, a plurality of series connected binary counters, switch means for selec'ively connecting said pickup heads to the input of the first of said counters, pulse shaping means for generating pulses of a predetermined fixed duration responsive to input pulses, second switch means for selectively coupling the outputs of said counters to said pulse shaping means to supply reference pulses at different rates thereto, a bistable trigger circuit having set and reset inputs and set and reset outputs, means establishing a threshold triggering level at said set input of said trigger circuit whereby same is triggered to energize said set output in response to a signal at said set input in excess of said threshold triggering level, means coupling the signal from said photoelectric means to said set input of said trigger circuit, an AND-gate having first and second inputs respectively coupled to the set output of said trigger circuit and to said pulse shaping means and having an output, a

memory record head disposed adjacent the periphery of said memory drum, amplifier means coupling the output of said gate to said record head, differentiating means coupled between said amplifier means and the reset input of said trigger circuit to develop reset pulses in coincidence with the trailing edges of pulses applied from said amplifier means to said record head, a memory pickup head disposed adjacent the periphery of said memory drum at a position of angular displacement from said record head corresponding to that between said inspection station and ejection mechanism, means coupling said memory pickup head to said ejection mechanism, and an erase magnet disposed adjacent the periphery of said memory drurnat a position displaced from said memory pickup head in the direction of memory drum rotation and between said memory drum pickup and record heads.

7. A sorting machine according to claim 6, further defined by said means coupling said memory pickup head to said ejection mechanism comprising a one-shot multivibrator including third switch means for selectively varying the delay thereof and coupled to said first and second switch means for correlated selecting action therewith.

8. A sorting machine according to claim 6, further defined by said means coupling the signal from said photoelectric means to said set input of said trigger circuit comprising a normalizing capacitor coupled to the output of said photoelectric means, amplifier means coupling said capacitor to the set input of said trigger circuit, bias means, a normally open normalizer switch coupling the junction between said capacitor and amplifier means to said bias means, said normalizer switch being actuatable to closed position in response to pulses applied to a control input thereof, a magnet carried by said conveyor wheel, a normalizer pickup head disposed adjacent said conveyor wheel for generating a pulse each time the conveyor wheel magnet passes same, and means coupling 16 said normalizer pickup head to the control input of said normalizer switch.

9. A sorting machine according to claim 8, further defined by means coupling said normalizer pickup head to reset inputs of said counters.

10. A magnetic memory device comprising a cylindrical housing including a bushing supported coaxially thereof, a shaft, bearing means within said bushing journalling said shaft for rotation coaxially of said housing, a memory drum coaxially mounted on said shaft within said housing and having a magnetic recording medium on its peripheral surface, at least one reference pulse generating drum of magnetic material and having a spur gear con-figuration mounted on said shaft within said housing, at least one reference pulse pickup head mounted within said housing adjacent the peripheral surface of each reference pulse generating drum, at least one memory record head mounted within said housing adjacent the peripheral surface of said memory drum, an erase magnet mounted within said housing adjacent the periphery of said memory drum, a memory pickup head, means mounting said memory pickup head within said housing adjacent the periphery of said memory drum for selective movement angularly thereof relative to said memory record head, and closure means at the ends of said housing traversed by said shaft.

References Cited UNITED STATES PATENTS 2,625,265 1/1953 Cox 209l11.6 2,789,224 4/1957 Leonard 340-l74.1 2,886,802 5/1959 Henning 340-474 3,275,136 9/1966 Allen 209-74 M. HENSON WOOD, 111., Primary Examiner.

R. A. SCHACHER, Assistant Examiner.