US3469689A

US3469689A - Improperly-sealed-container rejector

Info

Publication number: US3469689A
Application number: US546009A
Authority: US
Inventors: Thomas F O'neill Jr
Original assignee: Bron Electronics Inc
Current assignee: Bron Electronics Inc
Priority date: 1966-04-28
Filing date: 1966-04-28
Publication date: 1969-09-30
Anticipated expiration: 1986-09-30

Description

2 Sheets-Sheet 1 Filed April 28, 1966 flew? 9 7m .WJV2&&Z, r? g 014M, flu, WWW K United States Patent 3,469,689 IMPROPERLY-SEALED-CONTAINER REJECTOR Thomas F. ONeill, Jr., Lombard, 111., assignor to Bron Electronics, Incorporated, Lombard, Ill., a corporation of Illinois Filed Apr. 28, 1966, Ser. No. 546,009 Int. Cl. B07c /34 US. Cl. 209-80 3 Claims ABSTRACT OF THE DISCLOSURE Apparatus for electronically detecting and rejecting improperly sealed containers utilizing a proximity detector which controls the frequency of an oscillator in response to the distance between the detector and container top.

This invention relates to an improperly-sealed container rejector, and particularly a rejector for jars and the like which are supposed to be sealed under vacuum.

As is Well known, there are many comestibles which are sealed at other than atmospheric pressure. For example, baby food, jellies, other preserves, etc., are sealed in glass jars with twist-on caps. A comestible is canned, or placed in the jar, hot, and then is sealed in a vacuum with a twist-on cap. The jar then is cooled in a water spray, and subsequently a label is applied. The vacuum sealing plus the additional reduction in internal pressure of the container upon cooling thereof causes the lid to flex inwardly under atmospheric pressure. In some instances, lids are specifically constructed for optimum flexure. As will be recognized, it is also the practice to seal certain comestibles under presure, and in such instances the lids or container ends bow outwardly rather than inwardly.

A predetermined degree of departure from atmospheric pressure effects a predetermined lid or container end flexure. If, for some reason, a container is not properly sealed, then the cap or container end will not deflect t0 the intended degree. Thus, the degree of deflection of the cap or container end can be relied on to separate dud, or improperly sealed, containers from the great bulk of containers which are properly sealed. As will be appreciated, containers which are not properly sealed are subject to having the contents thereof spoiled in rather short order, thus making the contents at best unpalatable, and in some circumstances suificiently spoiled as to cause illness of anyone ingesting the contents.

Detection and ejection apparatus heretofore has been provided utilizing a low-travel electric switch to follow the contour of a container lid or end. Such switches typically have a life of about one million cycles. It is not at all uncommon to test 150,000 containers a day, and simple arithmetic indicates that a switch must be replaced after about seven days service life. Such early switch failure is well nigh intolerable, since it requires too much service time, too much down time of an assembly line, and may lead to improper operation, allowing a few containers to get by which should have been rejected.

Accordingly, it is an object of this invention to provide an apparatus for electronically detecting improperly sealed containers and for ejecting such containers.

Specifically, it is an object of this invention to provide an improperly-sealed-container rejector utilizing a proximity sensor to detect the degree of deflection of a container lid or the like, and thereby to segregate improperly sealed containers from those which are properly sealed.

It further is an object of the present invention to provide a detector and ejector for improperly sealed containers which is effective in operation, irrespective of the 3,469,689 Patented Sept. 30, 1969 ice speed of operation of a conveyor carrying the containers, and irrespective of the spacing of the containers.

Other and further objects and advantages of the present invention will be apparent from the following description when taken in connection with the accompanying drawings wherein:

FIG. 1 is a perspective view in somewhat stylized form of an improperly-sealed-container rejector constructed in accordance with the principles of the present invention;

FIG. 2 is a top view of a portion of the rejector;

FIG. 3 is a vertical cross-sectional view as taken substantially along the line 3-3 in FIG. 1;

FIG. 4 is an electronic block diagram showing the electronic principles of the present invention; and

FIG. 5 is a series of wave shapes showing the correspondence in operation relative to properly sealed and improperly sealed containers.

Referring now in greater particularity to the drawings, and first to FIGS. 1-3, there will be seen a conveyor mechanism 10 shown somewhat idealistically as comprising a conveyor belt having an upper reach 12 and a lower reach 14 passing over an idler cylindrical roller 16 and a driven roller 18, the latter being driven from a power source such as an electric motor 20. A series of containers illustrated as jars 22 is supported in sequence on the upper reach 12 of the conveyor belt for translation or transportation of the jars. Each jar has partial thread convolutions 24 formed at the upper circumference thereof, and lids 26 are provided with inwardly directed lugs 28 for rotationally locking beneath the thread convolutions. The jar and lid are well known, and will be understood to require only about a quarter-turn for locking. As is seen particularly in FIG. 3 the top of the lid 26 is concave as indicated at 30, having a maximum deflection at the center 32. The lids or caps 26 may be shaped with concentric rings or the like to augment the inward deflection, but this is not essential to the principles of the present invention.

A top probe comprising a plastic mounting sled or skid 34 having rounded lower corners 36 is supported by a flat spring or resilient member 38 along the longitudinal path of movement of the jars. The sled is normally supported at a predetermined height above the upper groove reach 12 so that it will be cammed slightly upwardly by each successive jar lid. A proximity sensor (subsequenty shown schematicaly in FIG. 4) is housed Within the plastic sled or skid 34 substantially at the center thereof for detecting the requisite degree of deflection of the top surface of the the jar lid 26.

As will be apparent, it is essential that measurements be taken at corresponding locations on the jar lid in each case, since the amount of deflection will vary over the extent of the jar lid, being a maximum at the center as heretofore indicated. To insure reading at this center position, a side probe is provided, the side probe comprising a plastic member 40 housing a second, or side proximity sensor, also hereinafter shown schematically (in FIG. 4) directly adjacent the sides of the jar lids 26 as they move along with the upper reach 12 of the conveyor 10. Immediately beneath the side sensor or detector 40 there is provided an air nozzle 42 having an electrically controlled valve 44. The valve is normally closed. If an improperly sealed jar passes the sensors or detectors the valve 44 is momentarily opened and a jet of air knocks the jar off the side of the conveyor to a discharge receptacle.

Turning now to FIG. 4, the side probe 40 is seen electrically to comprise an electrical element the reactance of which changes in accordance with metal proximity, specifically an inductance coil 46 grounded at one end and having the opposite end connected at 48 to an oscillator 50. A tap 52 on the inductance coil 46 is connected to a resistor 54 having a sliding tap 56 thereon connected to the oscillator 50. The proximity of the jar lid to the side probe determines the frequency and amplitude of the oscillator 50. The particular sensor shown operates on an inductance principle, but capacitance also could be used. The specific inductive sensor is one commercially available, made and sold by Electro Products. The sensor previously has been used for counting cans and the like, but to the best of my knowledge has not been used in any way for detecting anything about proper or improper sealing of a container. The oscillator signal is coupled to a detector 58 to convert the AC. oscillations to DC potential. The detected DC. potential is amplified by an amplifier 60, and the output thereof is applied to the top end of a potentiometer resistor 62. The poentiometer resistor is provided with a sliding tap 64, the bottom of the resistor 62 being grounded, and the tap 64 is connected to a Schmitt trigger circuit 66 to produce a square wave output whenever the side sensor 46 detects the nearest approach of a jar lid. The Schmitt trigger circuit is connected to a capacitor 68 to convert the square wave to a pulse, and this is connected to an inverter 70, the output thereof being illustrated to the right at 72. The output is connected to a line 74, of which more will be said later.

A very similar, but not identical circuit is applied in connection with the center probe 34. The center probe likewise comprises a sensor in the form of an inductance 76 grounded at the bottom and having the top thereof at 78 connected to an oscillator 80. A tap 82 on the inductance 76 is connected to a resistor 84, and a sliding tap 86 on the resistor is connected to the oscillator 80. The oscillator in turn is connected to a detector 88 to provide a direct current potential corresponding to the AC. oscillations from the oscillator 80, and the detector is connected to an amplifier 90. The amplifier 90 is connected through an emitter-follower circuit 92 to the top of a potentiometer resistor 94, the bottom thereof being grounded. The sliding tap 96 on the potentiometer resistor 94 is connected to a Schmitt trigger circuit 98, and the Schmitt trigger circuit is connected direct to an inverter 100. The output of the inverter 100 is connected to a line 102, as will be taken up shortly hereafter, and the output of the inverter is illustrated at the right thereof, either somewhat in the form of a W 104- in the case of a properly sealed jar or container, or somewhat in the form of a wide U 106 in the case of an improperly sealed jar.

The two

output lines

74 and 102 are connected to the input of a nor gate 108 and the output of the nor gate is connected to a one-shot multivibrator 110. The multivibrator in turn is connected to an emitter-follower 112, and this is connected to the movable element 114 of a switch 116 having fixed

contacts

118 and 120. The fixed contact 118 is connected to a power amplifier 122, and the power amplifier 122 is connected to the air valve 44. The fixed contact 120 is connected to a test light 124, the opposite side thereof being grounded.

-As each jar passes the two probes, the frequency of oscillation of the

respective oscillators

50 and 80 is brought to a predetermined frequency and amplitude, this being adjustable by means of the respective

adjustable resistors

54, 56 and 84, 86. A final adjustment is made by means of the

potentiometers

62, 64 and 94, 96 to the respective Schmitt trigger circuits. The adustments are made on the circuit or channel associated with the center probe so that the desired oscillator output will cause triggering of the Schmitt trigger circuit when the maximum deflection of the lid is encountered, assuming the maximum deflection is greater than the predetermined minimum. Actually, in most instances, the deflection will somewhat exceed the predetermined minimum, and the Schmitt trigger 98 will be triggered just before the maximum deflection is reached, and the center raised portion of the square wave at 126 results. As to the circuit or channel associated with the side probe, adjustment is made so that the Schmitt trigger is triggered just as the edge of the jar lid comes the closest, i.e., along the transverse diameter of the lid, and this produces the relatively narrow spike 128 of the output wave 72.

The output Waves are overlaid as to time in FIG. 5, and it will be seen that the spike 128 coincides with the raised center portion 126 of the wave 104. As long as both the raised

portions

128 and 126 are generated, the nor gate 108 does not respond, and the air valve 44 remains closed.

On the other hand, if the deflection of the lid does not reach or exceed the predetermined minimum, due to improper sealing of the jar, then the wave 106 is produced. The raised portion or pip 126 is missing. This causes actuation of the nor gate 108 to cause the one-shot multivibrator 110 to operate, and thereby to actuate the air valve 44 to cause the nozzle 32 to eject a blast of air, and thereby to blow the jar off the side of the conveyor.

It will be seen that the present invention provides for withdrawal or segregation of improperly sealed containers, relaying on concavity of the lid. As will be appreciated, the straight underportion of the sled or top probe 34 is more than long enough to span the diameter of a jar, whereby the sensor is held at a predetermined level relative to the upper level of the jar lid or top. When the pips or projections of the Waves produced by the two probes coincides, the jar is passed. However, when one of them is missing, due to improper deflection of the jar lid, the air valve is actuated and the improperly sealed jar is blown from the side of the conveyor.

The specific example of the invention as herein disclosed is for illustrative purposes only. Various changes in structure will no doubt occur to those skilled in the art.

The invention is claimed as follows:

1. Apparatus for rejecting improperly sealed containers comprising a detecting station, means for moving a series of substantially cylindrical containers having substantially circular ends past said station in sequence, electronic detection means at said detecting station electrically cooperative with said containers in sequence, the containers being moved transversely with their ends proximate to said detection means, the electric reactance of said detection means varying in accordance with the proximity thereto of a container and the proximity varying in accordance with the deflection of said container in accordance with the difference in internal pressure therein from atmospheric, means causing the electronic detection means to read substantially at the center of a container end comprising a second electronic detection means at said detecting station and positioned proximate to the side of a container and operative at the closest approach of a container free of contact therewith to cause the first-mentioned electronic detection means to read, ejection means adjacent to said moving means for ejecting an imporperly sealed container from said moving means, and control means interconnecting said detection means and said ejection means to operate said ejection means when said detection means detects a container deflection diifering from a predetermined norm, said control means including a nor gate conjointly controlled by both of said electronic detection means.

2. Apparatus for rejecting improperly sealed containers comprising a detecting station, means for moving a series of substantially cylindrical containers having substantially circular ends past said station in sequence, electronic detection means at said detecting station electrically cooperative with said containers in sequence, the containers stantially at the center of a container end comprising a second electronic detection means at said detecting station and positioned proximate to the side of a container and operative at the closest approach of a container free of contact therewith to cause the first-mentioned electronic detection means to read, ejection means adjacent to said moving means for ejecting an improperly sealed container from said moving means, and control means interconnecting said detection means and said ejection means to operate said ejection means when said detection means detects a container deflection differing from a predetermined norm, said control means including a gate conjointly controlled by both of said electronic detection means, said control means comprising a pair of oscillators respectively connected to the two electronic detection means, the frequency of said oscillators respectively being controlled by said electronic detection means, a pair of pulse-producing means connected to and operated according to the output of said oscillators, and means connected to said pair of pulse-producing means for comparing said pulses.

3. Apparatus as set forth in claim 2 wherein the pulse- 6 producing means comprises a pair of detectors for converting the outputs of the two oscillators to DC, and a pair of Schmitt trigger circuits respectively controlled by said pair of detectors, and wherein the means for com paring the pulses comprises a nor gate.

References Cited UNITED STATES PATENTS 3,195,724- 7/1965 Whitacre 20988 3,206,025 9/1965 Ochs 209 3,266,627 8/1966 Ochs 20980 3,064,807 11/1'962 Stover 209-80 3,137,160 6/1964 Mathias 7352 3,206,027 9/ 1965 Bailey 20980 3,295,676 1/1967 Ochs 20980 3,392,829 7/1968 Keinanen 20980 X ALLEN N. KNOWLES, Primary Examiner U.S. Cl. X.R. 209111.8