U.S. patent number 3,928,753 [Application Number 05/435,499] was granted by the patent office on 1975-12-23 for small object counting apparatus.
This patent grant is currently assigned to Engineering Development Associates, Incorporated. Invention is credited to Robert J. Champion, Jesse P. T. Harris, William D. Kivett.
United States Patent |
3,928,753 |
Kivett , et al. |
December 23, 1975 |
Small object counting apparatus
Abstract
Small objects, such as pharmaceutical capsules from a production
stream, are counted with speed and accuracy. The objects are
delivered to a hopper from which they are picked up by a rotating
suction drum and transported through an orientation means to an
object pick-off or drum stripping means. Following separation from
the drum, the objects pass sequentially through an electro-optical
sensing device which delivers electrical pulses to an electronic
counter means which has the ability to display both count and rate
of count. The counted objects are delivered to a suitable batch
container.
Inventors: |
Kivett; William D. (Taylors,
SC), Champion; Robert J. (Greenville, SC), Harris; Jesse
P. T. (Greenville, SC) |
Assignee: |
Engineering Development Associates,
Incorporated (Mauldin, SC)
|
Family
ID: |
23728651 |
Appl.
No.: |
05/435,499 |
Filed: |
January 22, 1974 |
Current U.S.
Class: |
377/6; 221/211;
235/98C; 377/53 |
Current CPC
Class: |
G06M
7/00 (20130101); G06M 1/101 (20130101) |
Current International
Class: |
G06M
1/00 (20060101); G06M 1/10 (20060101); G06M
7/00 (20060101); G06M 003/00 () |
Field of
Search: |
;235/92PK,98C,92V
;221/211,7 ;198/287 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Thesz, Jr.; Joseph M.
Attorney, Agent or Firm: Fishburne, Jr.; B. P.
Claims
We claim:
1. An apparatus for counting large quantities of small objects with
accuracy comprising an object infeed hopper, a horizontal axis
object transport drum having plural spiral rows of suction ports
mounted for rotation at the object discharge end of the hopper,
means to turn the drum on its horizontal axis in one direction,
means to create a partial vacuum in the drum during its rotation so
that said suction ports may pick up objects from the hopper, an
excess object rejection device fixedly mounted relative to the
periphery of the drum and spaced from the hopper and allowing only
one object to be transported by each suction port of the drum
beyond said device, an object pick-off member fixedly mounted at
the side of the drum remote from the hopper and spaced from said
device and having inclined object guidance channels corresponding
in number to the number of suction ports in each spiral row on said
drum, said pick-off member removing objects from said suction ports
with a scraping action during rotation of the drum and causing such
objects to slide through said channels, electro-optical object
sensors on the pick-off member adjacent to each channel thereof
responding to the sequential passage of objects through the
channels and producing sequential electrical pulses representative
of the number of objects passing through the channels, counter
means electrically coupled to said electro-optical sensors for
totalizing the number of objects sequentially passing through all
of said channels until a present count is obtained, means arranged
above said hopper, drum and pick-off member for directing ionized
air downwardly to agitate and clean objects resting in the hopper
and for aiding the passage of objects through said object guidance
channels, and said last-named means comprising an ionization
chamber having a slotted bottom wall, a metal plate having a
multiplicity of dependent needles positioned within said chamber
above said slotted bottom wall, means for applying high voltage
alternating current to said plate, and means for directing air
forcibly into said chamber.
2. The apparatus of claim 1, and said excess object rejection
device comprising a comb-like member extending axially of said drum
for substantially its entire length and having plural equidistantly
spaced equal width slots formed therein and said slots
corresponding in number to the suction ports in each spiral row and
aligned with the ports circumferentially of the drum.
3. An apparatus for counting large quantities of small objects with
accuracy comprising an object infeed hopper, a horizontal axis
object transport drum having plural spiral rows of suction ports
mounted for rotation at the object discharge end of the hopper,
means to turn the drum on its horizontal axis in one direction,
means to create a partial vacuum in the drum during its rotation so
that said suction ports may pick up objects from the hopper, an
excess object rejection device fixedly mounted relative to the
periphery of the drum and spaced from the hopper and allowing only
one object to be transported by each suction port of the drum
beyond said device, an object pick-off member fixedly mounted at
the side of the drum remote from the hopper and spaced from said
device and having inclined object guidance channels corresponding
in number to the number of suction ports in each spiral row on said
drum, said pick-off member removing objects from said suction ports
with a scraping action during rotation of the drum and causing such
objects to slide through said channels, electro-optical object
sensors on the pick-off member adjacent to each channel thereof
responding to the sequential passage of objects through the
channels and producing sequential electrical pulses representative
of the number of objects passing through the channels, counter
means electrically coupled to said electro-optical sensors for
totalizing the number of objects sequentially passing through all
of said channels until a present count is obtained, said
electro-optical sensors each comprising a light source disposed on
one side of each guidance channel and a photo-sensitive element on
the other side of each channel optically aligned with the light
source for that channel, each channel having a light transmitting
passage extending thereacross adjacent to said light source and
photo-sensitive element, and an automatic brightness intensity
control circuit for each light source electrically connected with
the source and the associated photo-sensitive element, whereby a
reliable count for objects of varying translucency may be had, each
brightness control circuit being a transistorized circuit including
a time constant network constructed so that the source current can
respond only to relatively slowly varying changes in time constant
input voltages.
4. The apparatus of claim 3, and said brightness control circuit
additionally comprising a single pulse generator which generates a
pulse of a longer time duration than the maximum light beam
interruption time of an object being counted thus insuring that
only a single fixed time pulse is generated for each beam
interruption, said brightness control circuit additionally
comprising a differentiator circuit adapted to form short duration
pulses which may be gated into a single counter circuit.
Description
BACKGROUND OF THE INVENTION
The pharmaceutical industry, due to an ever-increasing demand for
more reliable and uniform products, is experiencing an increasing
need for automation processing and handling equipment. Among the
specific needs being encountered by the industry is the necessity
for a high speed apparatus to receive gelatin capsules or medicinal
tablets from a production stream and to count them accurately in
great number while delivering them to suitable batch
containers.
Ideally, an apparatus or machine for this purpose should be capable
of counting the various small objects at rates in the range of
200,000 per hour and with a typical accuracy of plus or minus
0.01%. The apparatus should be able to handle a range of object
sizes and shapes as well as objects possessing different degrees of
translucency. In the interest of economy, the apparatus should
occupy only a minimum of floor space which, in the case of the
invention, is only 2 square feet approximately. It should be easy
to operate with a minimum number of simplified controls and should
possess an ability to visually display both the object count and
the rate of count. The apparatus should also have the ability to
process gelatin capsules and the like without damaging them in any
way. The invention actually cleans the product during the counting
process by removal of dust and product deionization. The apparatus
should also be reasonably rugged and durable and should require
minimum maintenance. In furtherance of these two objectives, the
present invention features an absence of vibratory components which
naturally tend over a long period of time to destroy a machine.
Accordingly, the object of the invention is to provide a small
object counting apparatus which possesses all of the
above-enumerated desirable features, plus others that will become
apparent during the course of the following detailed description.
The invention, for example, embodies a unique mechanical
arrangement and coacting electrical controls whereby the
statistical chance for simultaneous occurrence of electrical pulses
being delivered to a counter by the electro-optical sensor is
reduced substantially to zero. Another unique feature of the
invention resides in the provision of a slow-acting automatic
intensity control circuit which adjusts the brightness of each
individual light source to maintain just enough brightness to be
detectable at the associated phototransistor. This allows faithful
detection of transparent objects which may produce only partial
light beam interruption as well as objects having a greater degree
of opacity.
Another significant feature of the invention embodied in the
controls thereof is the ability of the apparatus to count objects
up to within a small number, typically 20, of a desired total, and
then to automatically slow down drum rotation to provide a mere
trickle count up to the exact total, whereupon the object
transporting drum is stopped and the flow of objects into the
hopper may also be stopped upon reaching the desired count. In
general, the appparatus embodying the invention possesses
flexibility of operation and control, simplicity, compactness and
economy, both in terms of manufacturing and usage including
maintenance.
BRIEF DESCRIPTION OF DRAWING FIGURES
FIG. 1 is a perspective view of an apparatus for counting small
objects in accordance with the present invention;
FIG. 2 is a fragmentary perspective view of the apparatus;
FIG. 3 is a fragmentary vertical section taken through a rotary
suction drum, hollow shaft and associated parts;
FIG. 4 is a fragmentary vertical section taken transversely through
the drum, object sensing unit and other associated parts;
FIG. 5 is an enlarged fragmentary cross section through the sensing
unit taken on line 5--5 of FIG. 4;
FIG. 6 is a fragmentary exploded perspective view showing elements
of the electro-optical sensing unit; and
FIG. 7 is a schematic view of a circuit for automatically adjusting
the brightness of light sources in the object sensing unit in
accordance with variations in the translucency of objects being
counted.
DETAILED DESCRIPTION
Referring to the drawings in detail wherein like numerals designate
like parts throughout, the complete apparatus as depicted in FIG. 1
embodies a floor-mounted housing 10 to enclose a rotary drum drive
motor and associated controls and the like, to be described. Above
the housing 10 is the central section of the apparatus including
frame sides 11 which form a partial enclosure for the small object
supply, transporting and pick-off means, all to be described in
detail. Above this section of the apparatus and mounted thereon is
an ionization chamber or section 12, and on top of this is mounted
the object counter and display unit of the invention designated
generally by the numeral 13. It may be pointed out here that the
entire apparatus is typically constructed to be no more than about
40 inches in height by about 20 inches wide by approximately 20
inches deep, front-to-back. The apparatus is therefore very compact
so that it will occupy the absolute minimum of floor space.
Mounted between the intermediate vertical frame sides 11 or plates
is a horizontal axis rotating transport drum 14 for the small
objects being counted and the opposite end plates 15 of the drum
carry shaft sections 16, one of which is hollow with a through bore
17, as shown in FIG. 3. The opposite end shaft section 16, FIG. 4,
is solid. A pair of axially aligned bearings 18 for the drum shaft
sections 16 are securely mounted as at 19 through a rigid plate on
the outer sides of frame elements 11. The hollow shaft section 17
projecting from one end of the drum 14, FIG. 3, is enclosed by a
cup-like housing 20 snugly fitted on the adjacent bearing 18. A
tubular sleeve 21 secured to the housing 20 is adapted to connect
to any external source of vacuum, not shown in the drawings.
As an important feature of the invention, the hollow drum 14 which
is subjected to vacuum through the hollow shaft 17 during rotation
is provided with a plurality of equidistantly circumferentially
spaced spiral rows of small suction apertures 22. In the
illustrated embodiment, the suction transport drum 14 may have six
spiral rows of apertures with ten apertures per row, and each
adjacent pair of apertures separated circumferentially of the drum
by 6.degree.. The importance of the spiral rows of apertures is in
connection with the delivery of individual small objects
sequentially and non-simultaneously to pick-off channels, yet to be
described. The drum 14 rotates during the operation of the
apparatus under the influence of a drive pully 23 connected to the
solid shaft end of the drum, the pulley being connected with a
transmission belt 24, in turn driven by an electric motor 25
contained within the housing 10 together with a motor control
assembly 26 shown diagrammatically in FIG. 2.
As inclined hopper tray 27 at the product input side of the drum 14
is suitably supported between the frame sections 11 with its
leading transverse edge 28 disposed close to the periphery of the
drum 14 somewhat below the horizontal rotational axis thereof. The
hopper tray receives gelatin capsules or like small articles
directly from a production stream, and the product readily
gravitates down the inclined tray to pile up in a mass behind the
rotating suction drum.
At the top of the drum, a single inclined comb-like orientation
plate 29 having equidistantly spaced slots 30 is fixedly and
interchangeably mounted between the frame sides 11. The slots 30
correspond in number to the apertures 22 of each spiral row of
apertures and one slot 30 is aligned with one aperture of each row.
As an individual capsule or like small article in the tray 27 is
picked up by one of the suction apertures 22 and conveyed upwardly
by the drum, the slotted member 29 will allow the passage of one
and only one capsule beyond it and any other objects which might be
adhering to the drum will be rejected and will fall back into the
tray or hopper. The slots 30 are sized, therefore, to allow passage
through them of only one object at a time of a given size. The
plate 29 may be replaced in the apparatus by different plates
having different sizes of slots so that the apparatus may be
capable of counting various small objects differing in shape and
size. The lower edge of the plate 29 is disposed close to the
periphery of the rotating drum.
Immediately above the slotted member or plate 29 is the
aforementioned ionization chamber 12 which is a box-like housing
having a bottom wall 31 provided with a plurality of transversely
elongated slots 32, most of which are above the hopper portion of
the apparatus but several of which are on the downstream side of
the plate 29 remote from the hopper. A stationary metal plate 33
within the ionization chamber 12 is connected by a wire 34 with an
AC high voltage source 35. The wire 34 may extend through a conduit
36 receiving forced air from a suitable blower, not shown. Such air
is delivered into the ionization chamber and picks up charged ions
from a multitude of dependent needles 37 on the plate 33. These
charged ions travel through the exit slots 32 at the bottom of the
ionization chamber and are sprayed onto the small objects being
transported. This ionized air bath assists in removing any static
charge and/or dust from the objects, tends to blow rejected objects
back toward the hopper and away from the plate 29, agitates the
objects resting in the hopper, and assists the objects in passing
through channels of the pick-off means and electro-optical sensor,
yet to be described. Therefore, the ionization means serves several
important purposes simultaneously during the operation of the
apparatus.
At the discharge side of the drum 14 remote from the hopper or tray
27, there is mounted in the intermediate section of the apparatus
defined by the frame sides 11 an object pick-off and sensing
assembly designated broadly by the numeral 38. This is a very
essential and important component of the invention and it includes
a fixed pick-off bar 39 having plural parallel equidistantly spaced
channels or troughs 40 formed therein corresponding in number and
spacing with the slots 30 and the apertures 22 in each spiral row.
The product intake end 41 of the pick-off bar 39 is arranged close
to the periphery of the drum so that the pick-off bar will scrape
off and remove the capsules being transported by the suction
apertures 22. One capsule or object will be separated from each
aperture 22 and will be delivered to one of the channels 40 of the
pick-off bar, which channels are inclined so that the small objects
therein will gravitate downwardly.
Toward the discharge end of the pick-off bar 39, FIG. 4, a
relatively shorter inverted and mating pick-off bar cover 42 is
fixedly mounted thereon and this cover has inverted channels 43
which register in assembly with the channels 40, see FIG. 5.
Openings 44, for a purpose to be described, are formed through the
top of the pick-off bar cover, and the top of the cover also has a
continuous longitudinal recess 45 parallel to the drum axis for
receiving and seating a tranparent plate 46 in covering relation to
the openings 44. Similarly, the pick-off bar 39 near its lower
discharge end has slots 47 leading from its channels or troughs 40
and adjacent these slots the bottom of the pick-off bar 39 has a
recess 48 similar to the recess 45 to receive and seat another
transparent plate 49.
Channels bars 50 facing in opposite directions, FIG. 4, are secured
to the top and bottom, respectively, of cover 42 and pick-off bar
39 and these channel bars receive spacer plates 51 which are
apertured at 52 adjacent to each slot 47 of the pick-off bar and
each opening 44 of the pick-off bar cover 42. The channel bars 50
are similarly apertured at 53 in alignment with the apertures 52,
as clearly shown in FIG. 5.
Circuit panels 54, such as printed circuit elements, are mounted
above and below the two spacers 51 in the electro-optical sensor
which forms a part of the assembly 38. The upper panel 54 carries a
plurality of infrared light point sources 55 corresponding in
number to the channels or tunnels formed by the opposing pick-off
bar 39 and cover 42, as shown in FIG. 5. Similarly, the lower panel
54 carries a like number of phototransistors 56 or equivalent
elements and these phototransistors are optically aligned through
the described openings and transparent plates 46 and 49 so that the
phototransistors may be sensitive to infrared light generated by
the sources 55 or the interruption of such light beams by capsules
gravitating through the inclined tunnels designated 57 in FIGS. 4
and 5. The upper and lower units of the electro-optical sensing
means are enclosed and protected by suitable covers 58.
The aforementioned counter and display assembly 13 at the top of
the ionization chamber 12 is essentially conventional equipment
like the motor control assembly 26 and need not be described in any
great detail. It accepts the electrical signals generated by the
described electro-optical sensing means of the pick-off assembly 38
which occur somewhat sequentially due to the spiral arrangement of
apertures rows 22. Processing of these signals in the unit 13 to
assure non-simultaneous occurrence is conventionally carried out.
An electronic counter and comparator means allows totalization of
the counted objects and comparison of the total with a preselected
number. A precount counter of the unit 13 senses when the count of
the objects is within a small number, typically twenty, of a
desired total. This allows generation of a signal by the unit 13 to
slow down drum rotation by motor control assembly 26 and allow a
trickle count of objects up to exactly the desired count or total.
Outputs from the counter assembly 13 to motor control assembly 26
allow stopping of the drum 14, and auxiliary outputs will stop the
flow of objects to the input hopper 27 when the desired count is
reached. An internal time base in conjunction with another counter
circuit allows display of the object passage rate in thousands per
hour with an averaging time of typically 30 seconds. The motor
control assembly 26 allows interfacing between drum drive motor 25
and the counter assembly outputs, as well as providing a manually
adjustable drum drive speed.
A notable feature of the invention resides in the ability of the
sensing unit 38 to compensate automatically for any variations in
the translucency of the light paths between the elements 55 and 56
caused by dust accumulating on the plates 46 or for similar
reasons. This feature enables the apparatus to count objects having
different degrees of translucency. This important feature is
embodied in the electronic circuit illustrated in FIG. 7 of the
drawings. Referring to this figure, the light emitter or point
source 55 illuminates phototransistor 56 across one of the viewing
channels 40, FIG. 5. The phototransistor 56 conducts, causing the
voltage at the base of a transistor 59 to decrease toward zero
volts. Transistor 59 is an emitter-follower, whereby the voltage at
its emitter is equal to its base voltage minus 0.7v. This emitter
voltage is fed through the time constant network composed of
capacitor 60 and resistors 61 and 62 to transistor 63.
This transistor 63 conducts current through another resistor 64 and
light emitter 55. The amount of conduction current and thus the
intensity of brightness is proportional to the voltage applied to
the time constant network. The time constant network is adjusted so
that the source current can respond only to slowly varying changes
in time constant input voltages, typically more slowly than about 2
seconds.
In operation, the brightness is automatically adjusted to maintain
about +1.1 volts at the emitter of transistor 59. This is +1.1
volts is also coupled through diode 65 and resistors 66 and 67 to
produce about +0.4 volts at the base of second transistor 68. This
+0.4 volts is too small to cause conduction of transistor 68, and
its collector voltage is about 5 volts.
If an object 69, such as pharmaceutical capsule, rapidly interrupts
the beam between infrared light emitter 55 and phototransistor 56,
the voltage at the base and emitter of transistor 59 increases
toward +5 volts. If the time of interruption of the light beam is
of the order of a fraction of a second, no change in the light
source brightness is produced through transistor 63 because of its
relatively long time constant.
The increasing voltage at transistor 59 emitter is also coupled
through diode 65 to the base of transistor 68. If the increase is
as much as 0.3 volts, this transistor will conduct to a saturation
point. Its collector voltage then changes rapidly from +5 volts to
near 0 volts.
This change to 0 volts triggers integrated circuit 70. Once
triggered, this circuit generates one pulse at its pin numbered 8
of a fixed time duration. This time duration, set by capacitor 71
and resistor 72, typically 70 milliseconds, is designed to be
longer than the maximum interruption time of the object 69 being
counted as it passes between the elements 55 and 56. This insures
that only one fixed time pulse at the pin numbered 8 of element 70
is generated for each beam interruption.
Integrated circuit 73 is arranged as a differentiator, forming one
very short duration pulse which occurs at the positive-going
transition of the 70 millisecond input pulse, before mentioned. The
output zero-going pulse is typically 70 .times. 10.sup.-.sup.9
seconds.
Ten of the above-described automatic brightness control circuits
are employed in the counting system. Output pulses from each
circuit are parallel gated (summed) into one stream by other
conventional circuits, not shown, and then fed to one counter
circuit as a time-serial series of pulses to be counted, as
indicated generally at 74 in FIG. 7.
Summary of Operation
Objects, such as capsules 69, enter the hopper formed by tray 27
and adjacent side walls from a production stream, and are picked up
at the suction ports 22 of the rotating transport drum 14. A
comb-like element 29 strips excess picked-up objects from each
suction port, so that only one object will be transported by one
port beyond the element 29. Static charges and dust are removed
from the objects during pick-up and transport, both by the overhead
ionized air bath from slots 32 and the vacuum being drawn through
the ports 22.
The objects are carried by the drum 14 to the pick-off and sensing
assembly 38 where they are scraped from the drum at 41. FIG. 4, and
slide through the viewing channels 40 of pick-off bar 39 with an
air-assist from the overhead chamber 12. The generally sequential
pasaage of objects through the channels 40 produces sequential beam
interruptions between the elements 55 and 56 of each channel and
sequential electrical pulses into the counter assembly 13. These
pulses may overlap in time due to various uncertainties involved in
object passage through the channels 40. However, the beginning of
occurrence of the pulses, occupying an extremely brief period of
time, is utilized. Statistically, the chance of simultaneous
occurrence of the beginning pulse of any one channel with that of
another channel, and thus not being distinguishable as two separate
counts, is virtually zero. Consequently, these short beginning
pulses are serially counted in one direct electronic counter.
This process continues with the drum 14 rotating at a selected fast
speed, picking up and discharging objects through the channels 40,
and with the count accumulating until reaching a count of,
typically, 20 less than the quantity selected by the front panel
switches on counter assembly 13, see FIG. 1. At this count, signals
are sent out by the counter assembly to slow down drum rotation and
interrupt the object input drive system, not shown. The action
continues as before, but at a greatly reduced speed until exactly
the desired object count is obtained. At this time, the drum drive
is caused to stop completely.
During counting, the rate of object passage is visually displayed
on the front panel of the counter assembly 13. Controls on the
counter assembly allow manual starting, stopping of counter,
pausing and resuming operation without resetting the count.
It is to be understood that the form of the invention herewith
shown and described is to be taken as a preferred example of the
same, and that various changes in the shape, size and arrangement
of parts may be resorted to, without departing from the spirit of
the invention or scope of the subjoined claims.
* * * * *