Automated corn popping apparatus

This invention discloses an automated corn popping apparatus including a kettle assembly, a support arrangement for supporting and operating the kettle assembly, a display arrangement for enclosing the corn popping apparatus, and control means for automatically operating the corn popping apparatus. In a preferred embodiment, the kettle assembly includes a cast metal popping kettle and an agitator mechanism supported by a base adapted to receive pivot shafts. The support arrangement includes a mechanism for rotating the kettle assembly from a position for popping corn to a position for dumping corn into the display arrangement and a mechanism for raising and lowering the lid and rotating the agitator mechanism. The control means includes actuators for necessary mechanical movement, sensors of component position, and programmable means to receive sensor signals and control actuators to achieve the automatic popping of popcorn.

This application claims the benefit of U.S. Provisional Application No. 
60/005,495, filed Oct. 16, 1995. 
FIELD OF THE INVENTION 
The field of this invention relates to commercial popcorn poppers. More 
specifically it relates to efficient, reliable, and programmable corn 
popping assemblies and their enclosing support and display arrangements, 
which are especially useful in movie theaters and other places of 
entertainment. 
BACKGROUND 
At movie theaters and other entertainment venues, such as stadiums and the 
like, the rapid and efficient dispensation of foods and beverages is 
required because consumers are usually purchasing such products during 
intermission or other temporary disruptions of the show or event that is 
being or to be viewed. A particularly popular food product to be consumed 
at such venues is popcorn, and fresh serving hot, tasty popcorn to a large 
number of consumers in a rapid and efficient manner presents a difficult 
problem for counter attendants. Often only one or two persons attend the 
counter while many more are present to be served. 
One way to facilitate distribution of the product is to pop the corn and 
package it prior to the onset of the crowds, so that the packaged product 
can be rapidly dispensed when necessary. One problem here is that if done 
too early, the popcorn will not be as warm and tasty as freshly popped 
corn. In order to pop the corn, however, present commercial devices 
require the attendant to feed the corn, salt and oil into the kettle 
before each batch can be popped. 
There are different types of kettle designs which are used. One type has 
the support structure below the base of the kettle. The bowl is generally 
held in the operative position by a return spring, and is emptied by the 
attendant's manipulation of a side handle. If the attendant is not 
careful, however, the pivoting return motion of the bowl can be so hard 
and fast as to bounce upon and damage its supports. A solution to this 
problem is described in U.S. Pat. No. 5,035,173. Another design utilizes a 
ceiling mounting system for the kettle, with the handle and a spring lock 
positioned on the side of the housing. For either design, after the corn 
is fully popped, the attendant must move the handle to tilt the kettle to 
empty the popped corn therefrom. This diverts the attendant's time and 
effort to operation of the kettle for properly producing the product 
rather than serving the consumers. 
A fully automated system has been proposed in U.S. Pat. No. 5,035,173. 
While this system is satisfactory for many applications, the use of vacuum 
is noisy and the introduction of corn and salt into the kettle is not 
precise. Thus, there remains a need for an improved system for automating 
the production of popcorn. 
SUMMARY OF THE INVENTION 
It is a broad object of this invention to provide an integrated, efficient, 
reliable, safe, and programmable popcorn popping apparatus capable of 
automatic popping of tasty popcorn in commercial applications. Thereby, 
this invention includes a popcorn popping kettle assembly, a support 
arrangement for supporting and operating the kettle assembly for the 
popping of popcorn, a display arrangement for the commercial display of 
the elements of this invention in operation and of the freshly popped 
corn, and control means for the automatic control of the mechanical and 
electrical elements of this invention. 
The kettle assembly of this invention preferably provides for the mixing of 
corn and cooking oil so that the popcorn kernels become uniformly coated 
with cooking oil and subsequently provides for a uniform temperature 
suitable for popping the coated popcorn kernels. In a preferred 
embodiment, the kettle assembly includes a popping kettle, a base member, 
and an agitator mechanism. The kettle has a generally circular shape with 
a slightly sloping sidewall and a bottom, and is preferably made of cast 
or welded aluminum. The kettle includes a recess in the outer surface of 
the bottom for receiving heating means, which preferably are electric 
heating elements in thermal contact with the kettle. The heat provided is 
thereby distributed by conduction within the aluminum kettle for popping 
the popcorn at a substantially uniform temperature. 
The base member provides for the support and pivoting of the kettle 
assembly. In a preferred embodiment it includes dependent legs each of 
which accepts a pivot shaft about which the kettle assembly pivots from a 
popping position, which is substantially upright, to a dumping position, 
which is preferably substantially upside down. The kettle is spaced away 
from the base to define an open space for the passage of electric wires 
carrying power to the heating elements and signals from temperature 
sensing means, which are also attached to the bottom of the kettle. These 
feeds are routed from this space to the exterior of the kettle assembly 
through a hollow pivot axle, which communicates with a hollow bore in one 
of the dependent legs, which in turn communicates with the space between 
the base and the kettle. In this manner, pivoting of the kettle assembly 
causes minimal motion of electric wires, which necessarily carry high 
current to the heating elements and are thereby prone to damage. 
The kettle assembly further includes an agitator mechanism in the bottom of 
the popping kettle for mixing the corn kernels with the cooking oil and 
for insuring even popping of the popcorn. The agitator includes a hub 
supporting a plurality of agitator members. The hub is rotated by an 
agitator shaft, which enters the kettle from above to engage the hub for 
axial rotation. The agitator members can have any convenient 
configuration. The interior of the popping kettle and the agitator 
mechanism are coated with a non-sticking material such as Teflon for easy 
cleaning. 
The kettle assembly advantageously includes a material for insulating the 
sidewall of the popping kettle. The insulating material is generally 
placed between the kettle sidewall and an outer sheath, which is used to 
protect and retain the insulating material in position. The preferred 
insulating material is a ceramic sheet or blanket, and the preferred 
sheath material is a sheet of steel or aluminum. Thus the outer surface of 
the kettle assembly is significantly cooler than the temperature of the 
kettle; heat is uniformly distributed in the popping kettle; and cooking 
efficiency is improved. 
The support arrangement for the kettle assembly preferably provides for the 
support and control of the pivoting of the kettle assembly; for a kettle 
lid which can be raised from the kettle for entry of unpopped corn kernels 
and removal of popped corn; and for rotation of the agitator mechanism by 
an agitator shaft. Electric motors and power transmission means effect the 
necessary mechanical movements, and position sensing means provide 
feedback for the control of these motors. 
In a preferred embodiment, the kettle is pivoted by an electric motor 
coupled to one pivot shaft of the kettle assembly through a worm gear 
transmission and a sprocket and chain drive. The correct popping and 
dumping positions of the kettle are sensed by angular position indicators. 
In the preferred, but not limiting embodiment, these indicators are 
microswitches actuated by cams. In a further preferred embodiment, the 
agitator shaft is mounted above the kettle for axial rotation and can be 
lowered into the kettle whereupon it contacts and engages the hub of the 
agitator mechanism. Axial rotation of the agitator shaft is driven by a 
motor and gear assembly, which is coupled to the agitator shaft by two 
gears which are engaged when the agitator shaft is lowered into the 
kettle. 
A kettle lid, preferably of a circular sheet of stainless steel or 
aluminum, is mounted on the agitator shaft for relative vertical movement 
along the shaft and relative axial rotation to the shaft. It is retained 
by a retaining washer at a lowest vertical position. Thereby, the lid can 
be raised by the vertical motion of the agitator shaft sufficiently to 
permit entry and exit of popcorn and to permit free pivoting of the kettle 
assembly. Further, the lid can be lowered into contact with the kettle for 
retaining heat during popping of the popcorn. Additionally, the expanding 
bulk of the popping popcorn can freely urge the lid upward. Also, when the 
lid is otherwise supported by the wall of the kettle, the agitator shaft 
can rotate freely to drive the agitator mechanism. 
The vertical movements of the lid are sensed by vertical position sensors. 
In the preferred embodiment these sensors are microswitches contacted by 
the lid during its vertical movements. These microswitches are placed at a 
plurality of vertical positions, including at a first vertical position 
such that when the lid is positioned at this first position sufficient 
vertical height is available for the free pivoting of the kettle, a second 
vertical position such that at this second position the lid is in contact 
with the kettle assembly and the agitator shaft engages the agitator hub, 
and a third intermediate vertical position to which the lid is urged by 
the expanded bulk of a substantially completely popped provisioning of 
popcorn. In this manner feedback signals are generated for control of the 
vertical motion of the lid of the kettle and for sequencing of the popcorn 
popping cycle. 
In the preferred embodiment, the agitator shaft is vertically raised and 
lowered as well as axially rotated. This is accomplished by forming 
circular grooves in the rod for engaging a gear. These teeth must not form 
a spiral, or thread, in order to prevent vertical motion from occurring 
when the shaft is axially rotated for driving of the agitator mechanism. 
The gear engaging the rod is driven by a motor and gear transmission 
system. 
Thus, another aspect of the invention relates to a mechanism for imparting 
reciprocating linear motion and rotation, which comprises: an elongated 
shaft having a gear mounted thereon and a plurality of spaced grooves 
along its length; a first gear having a plurality of teeth of 
predetermined pitch which engage the grooves of the shaft, wherein 
clockwise rotation of the first gear causes longitudinal motion of the 
shaft in a first direction, while counterclockwise rotation of the first 
gear causes longitudinal motion of the shaft in a second direction 
opposite to the first direction, and a second gear mounted adjacent the 
shaft and capable of engaging the shaft gear for rotation of the shaft, 
wherein clockwise rotation of the second gear causes rotation of the shaft 
in a counterclockwise direction, while counterclockwise rotation of the 
second gear causes rotation of the shaft in a clockwise direction. The 
linear movement of the shaft causes the shaft gear to be moved from a 
first position where it engages the second gear so that the shaft can be 
rotated to a second position out of engagement with the second gear. The 
first and second gears are preferably driven by motor means which are 
actuated by position sensors. Advantageously, the shaft is operatively 
associated with the lid of a popcorn kettle for raising and lowering the 
lid during a popcorn popping cycle and one end of the shaft engages an 
agitator mechanism in the kettle when the gears are in the first position 
to rotate the agitator during rotation of the shaft. 
The control means provides for control of kettle temperature and for 
control of the mechanical movements of the kettle assembly and support 
arrangement. Temperature control means include means for sensing popping 
kettle temperature placed in good thermal communication with the kettle. 
In a preferred version, these sensing means include a thermocouple. A 
temperature controller accepts signals from the sensing means and 
energizes or de-energizes the heating elements to maintain an adjustable 
preset temperature. Preferably the heating elements are activated through 
a relay adapted for repetitive high current applications, such as a 
mercury relay. The temperature control means further include an 
independent temperature sensing means, also in good thermal contact with 
the popping kettle, which is set to open a control circuit at the maximum 
safe operating temperature, and thereby to prevent the kettle from 
reaching dangerous temperatures. In this manner an adjustable temperature 
may be accurately and safely maintained, and corn popping conditions 
adjusted for maximum efficiency and flavor. 
The mechanical control means accepts both operator requests and signals 
from the various position sensing means and outputs signals for actuating 
the various motors of the support arrangement. These means also accept 
signals representing the substantially complete popping of a provision of 
popcorn. In the preferred embodiment, such a complete popping signal is 
generated by the kettle lid being urged upward by the expanding bulk of 
popping corn contained in the kettle. This invention is adaptable to any 
alternative means to generate a complete popping signal, such as optical 
detection of the expanding popping popcorn. Optionally, these control 
means can accept and output signals to the temperature control means for 
providing overall control of all elements of the popcorn popping 
apparatus. In a preferred embodiment, the mechanical control means include 
both a programmable logic controller and associated circuits for 
controlling motor power and an operator control panel with request buttons 
and monitoring lights. Alternative embodiments are equally applicable to 
this invention, one such being a standard microprocessor controller with 
associated RAM, ROM, and interface circuits and with a keypad and an LCD 
type display panel for operator interaction. 
The mechanical control means are programmed to recognize requests for 
certain elementary mechanical operations of the support arrangement. In an 
preferred embodiment, these elementary operations comprise rotating the 
kettle to a popping or a dumping position, raising or lowering the kettle 
lid, rotating the agitator shaft, and controlling an associated cooking 
oil delivery system. These operations may be requested by means of control 
panel buttons, and their progress monitored by means of panel indicators. 
In a manual mode of operation, these elementary operations must be 
individually selected by the operator. In an automatic mode of operation, 
the logic controller automatically sequences these elementary operations 
to achieve substantially complete popping of a popcorn provision. For 
improved security, these modes are selected by a key lock, whereby an 
unskilled operator is prevented from perhaps operating the apparatus in a 
dangerous or destructive manner. 
The display arrangement of this invention provides for the attractive 
display of the apparatus, for storage of already popped corn, and for the 
protection of various mechanical elements and consumable supplies. This 
arrangement comprises an upper compartment, a display compartment, a 
middle compartment, and an optional lower compartment for support. The 
upper compartment houses various mechanical elements of the support 
arrangement. The display compartment provides for the attractive display 
of the kettle assembly and already popped corn. The middle compartment 
also houses air circulation and warming means whereby warm air can be 
recirculated through the display compartment to maintain the already 
popped corn in a warm and tasty condition. In a preferred embodiment, the 
middle compartment houses the control means. The optional lower 
compartment can house an associated cooking oil reservoir and delivery 
system and supplies of popcorn premixed with salt. In one embodiment, the 
popcorn premixed with salt is manually provisioned in the cooking kettle. 
In an alternative embodiment, automatic means can provision the popcorn 
into the kettle. 
The display arrangement can have numerous specific embodiments, each being 
directed to a particular commercial application. These applications 
include, for example, use in movie theaters or other places of 
entertainment in an area accessible to the public in which attractive 
display and decoration are important, or use in kitchen environment of 
such an establishment in which only functional display is important. 
Further, the various elements of the apparatus may be arranged in 
different manners as may be convenient. For example, the middle 
compartment can be eliminated and the warm air circulation and control 
means housed in the upper compartment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
For clarity of disclosure, and not by way of limitation, the detailed 
description of this invention is described with respect to an exemplary 
embodiment. However, it is apparent to those skilled in the relevant arts 
that related arrangements and embodiments of the components disclosed can 
be used to construct other embodiments of this invention that achieve 
equivalent efficiency, reliability, and programmable operation and that 
are within the scope of the claims. 
The principal elements of the invention are now described in detail 
beginning with the display arrangement, then the kettle assembly, followed 
by the support arrangement, and concluding with the control means. 
A. THE DISPLAY ARRANGEMENT 
FIG. 1 illustrates exemplary embodiment 101 of the kettle assembly, support 
arrangement, and display arrangement of this invention. The display 
arrangement comprises four compartments: upper compartment 102 houses 
portions of the support arrangement and provides passage for such cooking 
oil, electrical signals and power, and popping corn as are necessary to 
supply the kettle assembly for popping corn. Lower compartment 105 stores 
reservoirs of consumable materials, such as popping corn and cooking oil. 
Such storage is illustrated in U.S. Pat. No. 5,035,173, which is herein 
incorporated in its entirety by reference. As therein shown, cooking oil 
can be stored in conventional containers supplied with electrical heating 
elements and electrical pumps; also, the bag-in-the-box arrangement of 
U.S. Pat. No. 5,301,601 can be used. Corn can be stored in bins and 
provided to the kettle assembly by vacuum or air pressure feed methods. 
Compartment 105 also serves for access to building power supplies. In an 
alternative embodiment, the apparatus of this invention can be adapted to 
rest on a table of other support with lower compartment 105 absent. 
Middle compartment 104 provides support for control panel 106. Switches 107 
control display arrangement functioning, such as display compartment 103 
lighting and cooking oil heating. Portion 108 of the control panel is for 
control of the kettle assembly and is described below with reference to 
FIG. 8. 
Display compartment 103 kettle assembly 109, which is supported by side 
braces 110 of the partially illustrated support arrangement. Oil conduit 
111 transports heated cooking oil through kettle lid 112 into the kettle. 
Corn funnel and conduit 113 transport popping corn through opening 114 
into the kettle when lid 112 is lifted off the kettle. Corn conduit 113 is 
herein illustrated for an automatic arrangement for the provisioning of 
corn into the kettle whereby the corn is transported from a reservoir in 
compartment 105, mixed with salt, and provided in measured portions into 
the kettle. In an alternative arrangement for manual corn provision, corn 
conduit and funnel 113 would pass from the exterior, through from front 
panel 117, then through the other side brace. 
Display compartment has four vertical panels: 115, 116, 117, and 118. As 
herein illustrated, panels 115 and 117 are of an opaque rigid material, 
such as a high quality plywood or a wood/plastic laminate. Side panel 118 
may be of a transparent material such as glass, acrylic or plexiglass. 
Front panel 117 may be of the same material as the sides, with plexiglass 
preferred for the hinged access doors 119 and 120. It is understood that 
the construction of these panels is exemplary only. In a free standing 
application, where customers approach from all sides, panels 115, 117 and 
118 can be glass and front panel 116 can be plexiglass. Alternatively, in 
a recessed application, all but face panel 116 can be of less expensive 
opaque construction, such as plywood. In a further alternative, the doors 
illustrated can be replaced by one door, by three doors, by left handed 
doors, by sliding doors, and so forth, as may be demanded in a particular 
application. In addition, the lower portion of the compartment can have a 
pull-down drawer for access to the bottom of the compartment where the 
popped corn is retained for access thereto. 
Lighting elements 121 and 122 provide interior light to display kettle 
operation and available popcorn. There are exemplary only, and 
alternatively any suitable attractive or decorative lighting arrangement 
can be provided. Also depending on the application, it is understood that 
the exposed faces of the display arrangement can be provided with such 
decoration, labeling and illumination as are suitable for such devices. 
Affixed to side panel 118 is chimney 123 provided with a plurality of 
perforations for the passage of air. Air is drawn through these 
perforations in chimney 123, down into middle compartment 104 through 
opening 124 in panel 127. The air is heated in the middle compartment and 
passes through screen 125 to heat the popped popcorn contained in display 
compartment 103. As here illustrated, chimney 123 is made of a transparent 
material such as plexiglass to allow visual observation of the interior of 
the compartment. Alternatively, chimney 123 may be of opaque materials 
such as sheet metal, when visual access is not desired or needed. Screen 
125 has a mesh size which is sufficiently fine to prevent the majority of 
popped corn from passing through, but sufficiently coarse to permit 
unpopped corn kernel to pass through and be collected for removal from the 
compartment. Furthermore, excess cooking oil and other waste material can 
pass through screen 125. These undesired materials accumulate in the right 
half of the middle compartment, in drawer 126, and can be easily removed 
by removing and cleaning this drawer. 
The construction of the display arrangement is by any means known in the 
art. It is preferably that the framework be of welded or bolted metal 
elements of sufficient rigidity and strength that the kettle assembly may 
be operated without causing perceptible vibration or shaking. 
FIG. 2 illustrates in more detail middle compartment 104 of the display 
arrangement of this invention. Panel 127 and screen 125 are removed. 
Chimney 223 has opening 224 for the passage of air downward in direction 
225 from display compartment 103. This air is drawn in direction 221 by 
electric blower 227 and forced through compartment 228. This compartment 
contains a conventional electric heating element for warming the air. The 
air passes out of compartment 228 in direction 229 through perforations in 
face 230, and then through screen 125 into the display compartment in 
direction 231. 
Drawer 226, comprising front surface with a handle 233 and a tray 231 
having low sides 232, is for collecting and removing unpopped popcorn, 
waste oil, and other unwanted materials. The low sides 232 present a 
minimal obstruction to the flow of warmed air through the drawer. 
Compartment 233 contains the electrical controls of this invention and is 
fronted with control panel 206. 
The middle compartment is preferably constructed of sheet metal. 
Alternatively materials of equivalent strength and heat resistance can be 
used. 
B. THE KETTLE ASSEMBLY 
FIGS. 3A, 3B, and 3C illustrate in more detail kettle assembly 109 of FIG. 
1. FIG. 3A illustrates a top view of the kettle assembly showing the 
inside of the kettle with slightly inwardly sloping walls 301 and base 
302. The entire inner surface of the kettle is coated with a non-stick 
heat resistant material such as Teflon.TM. for easy cleaning. Also shown 
is an agitator assembly for mixing the corn with the cooking oil prior to 
popping to assure thorough coverage of the popcorn with the cooking oil 
and for agitating the corn during popping to insure as complete popping as 
possible. The agitator assembly, in an exemplary embodiment, comprises 
agitator arms 303 connected to coupler hub 304. These agitator components 
are preferably made of stainless steel and are connected by welding, 
although alternative metals and connections are possible. Alternative 
embodiments can comprise either more or fewer arms of bent or other 
non-straight configurations. The primary function of the agitator is to 
assure mixing of the corn and oil across the entire bottom surface of the 
bowl, with the particular orientation of the arms being sufficiently 
sized, configured and arranged to achieve this function. 
FIG. 3B illustrates a bottom view of the kettle assembly. Base 305 is 
attached to the kettle by bolts 306. The kettle assembly is supported by 
first pivot shaft 307 and by second pivot shaft 308. The first and second 
pivot shafts are coaxial so that the kettle assembly may be pivoted 
between an operating, or corn popping, and an emptying, or corn dumping, 
position. The pivot shafts are attached to base 305 by first leg 309 and 
second leg 310. Leg 310 and pivot shaft 308 are hollow and provide a means 
for electrical wires 311 to access the base of the kettle. 
FIG. 3C illustrates a median cross section of the kettle assembly showing 
details of its construction. This kettle assembly is similar to that 
disclosed in applicants' copending U.S. patent application Ser. No. 
08/328,325, which is herein incorporated by reference in its entirety. The 
kettle comprises slightly sloping side 301 with curved-over lip 312, 
substantially flat base 302, and thickened perimeter 314 under the base 
into which are screwed attaching bolts 306. Inside the kettle, the 
agitator mechanism comprises arms 303 and coupling hub 304. The coupling 
hub rotates on stub axle 313, which is fixedly attached to or through the 
middle of kettle base 302. Attached underneath the base of the kettle are 
electric heating means 316 and temperature sensing means 317. Preferably, 
the electric heating means is a conventional electrically resistive 
heating element and the temperature sensing means comprises a temperature 
sensing thermocouple and a bimetallic high temperature switch. The 
bimetallic high temperature switch is chosen to open above the maximum 
safe operating temperature of the kettle, which is approximately 
450.degree. F. Wires 311 provide electric power to the heating element and 
conduct temperature signals from the temperature sensing means. The kettle 
is constructed of heat conductive material of sufficient thickness that 
heat is evenly distributed throughout its interior for the even and 
complete popping of contained popcorn. Preferably the kettle is 
constructed of cast aluminum of a thickness no less than approximately 
0.25 inches. Welded aluminum, steel or stainless steel sheet can also be 
used to form the kettle. 
The kettle assembly is supported for pivoting by coaxial pivot shafts 307 
and 308 fixedly connected to legs 309 and 310, respectively. The legs are 
an integral part of base 305. Pivot shaft 308 and leg 310 are hollow and 
pivot shaft has a slot to permit access as shown of wires 311 to the 
components attached underneath the kettle. The base and the kettle, joined 
by attaching bolts 306, are separated by spacer sleeves 315 surrounding 
the attaching bolts at a distance sufficient to permit easy access of 
electrical wires 311 to components 316 and 317. The base is preferably of 
a cast metal, such as steel, stainless steel or aluminum. 
Another component of the kettle assembly is sheath 318. Sheath 318 is 
pressure fit to the perimeter of the base, as at 319, and slightly 
compressed under kettle lip 312. Alternatively, the sheath can be fixed to 
the base with machine screws. Optionally, insulation can be placed in the 
space between sheath 318 and the outer surface of the side of the kettle 
in order to conserve heat and thereby minimize the use of electric power 
for heating and to lower the exterior surface temperature of the kettle 
assembly for safety of operators of this invention. The sheath is 
preferably of sheet metal and most preferably of stainless steel sheet. 
Such sheet can be polished to present and an attractive exterior surface 
for the kettle assembly. 
The kettle attachment to base 305 permits easy kettle removal upon removal 
of bolts 306. Preferably, wires 311 have enough excess length so that the 
kettle may then be entirely lifted out of the base and sheath assembly. 
Easy removal of the kettle is important as the electric heating means and 
the temperature sensing means can require occasional repair or replacement 
because they are exposed to high heat and conduct high currents. 
Also shown in FIG. 3C are associated components of the supporting 
arrangement. Lid 320 is mounted on agitator shaft 322 at hole 321 for easy 
vertical displacements along shaft 322. When a provision of popcorn is 
just loaded, lid 320 rests evenly on kettle lip 312 for retaining heat in 
the kettle. However, as the popcorn pops and its volume expands, lid 320 
is urged upward along agitator shaft 322. The lid is preferably balanced 
with a center of gravity in hole 321 so such vertical displacements are 
effected with a minimum of force. The lid is preferably constructed of 
metal sheet, and most preferably of a rigid aluminum or stainless steel. 
Agitator shaft 322 is mounted in the supporting arrangement for vertical 
motion. When agitator shaft 322 is displaced vertically, retaining ring 
323, which is fixedly attached to shaft 322, also lifts lid 320. Agitator 
shaft 322 is also mounted for axial rotation, which is coupled through 
coupling hub 304 to the agitator mechanism. Hole 321 in lid 320 is of a 
size just sufficient to permit unimpeded vertical displacement along 
agitator shaft 322 as well as unimpeded axial rotation of agitator shaft 
322. 
Penetrating lid 320 is opening 325 for the provisioning of cooking oil into 
the kettle prior to popping the corn. Cooking oil is provided to opening 
325 through flexible tube 324, which is of a heat resistant construction, 
such as woven stainless steel. Alternatively, the oil may be provided 
through a rigid tube member which extends into the kettle through opening 
325. When a rigid tube is used, it must not be positioned too low to 
interfere with the rotation of the kettle during the emptying cycle. 
FIGS. 4A and 4B illustrate details of the bottom of agitator shaft 422, 
coupling hub 404, and stub axle 413. Coupling hub 404 fits over stub axle 
413 for free axial rotation. Stub axle 413, fixedly mounted on or through 
kettle base 413, has circular slot 405 near its upper end. Slot 405 freely 
accommodates pin 406, which is fixedly but removably mounted in coupling 
hub 404 through hole 407. In this manner, with pin 406 in place, coupling 
hub both freely rotates on stub axle 413 and remains in place when the 
kettle assembly is pivoted for dumping of popped corn. When pin 406 is 
removed, the coupling hub can be removed from the stub axle for cleaning 
or repair. 
Coupling hub has an inclined upper perimeter culminating in teeth 409 and 
410. These teeth engage with pin 410 which if fixedly inserted through 
agitator shaft 422 for rotation in the direction indicated at 411. This 
sloping but toothed configuration permits easy engagement of coupling hub 
404 with agitator shaft 422 when the shaft is lowered to contact the hub 
regardless of the angular orientation of pin 401. This configuration is 
superior to a configuration in which the upper surface of hub 404 is 
simply slotted. A slotted configuration requires exact alignment of such a 
slot with pin 410 in order to ensure positive engagement of the shaft and 
the hub. 
C. THE SUPPORT ARRANGEMENT 
FIG. 5 illustrates a side view, with respect to the orientation illustrated 
in FIG. 1, of the support arrangement of this invention. In an exemplary 
embodiment, the physical structure of the support arrangement comprises 
horizontal cross member 501 to which are attached vertical brace members 
510 and 511. This physical structure is supported by horizontal members 
502 and 503 which are anchored to the physical structure of the display 
arrangement of FIG. 1. Kettle assembly 509 is attached to this structure 
by coaxial pivot shafts 507 and 508 which are rotatably attached to the 
brace members by journals 530 and 531. These journals must be of 
sufficient strength and reliability to permit numerous cycles of rotation 
of the heavy kettle assembly, and preferably contain support bearings. 
Support bushings are less preferable. Wires 511 supply power to the 
electrical heating means carry temperature signals from the temperature 
sensing means in the kettle assembly. These wires pass through hollow 
pivot shaft 508 and hollow leg member 510. 
The operating steps of the invention is now described. Operation of the 
invention is divided into popping cycles. A cycle begins with the kettle 
positioned in the substantially upright position as illustrated in FIG. 5 
and kettle lid 520 lifted substantially to the position of microswitch 
532. FIG. 5 illustrates the kettle lid in a partially lifted position. 
When the unit is first turned on each day, the kettle is initially heated 
to the desired corn popping temperature of about 430.degree. F. A 
temperature controller (described in greater detail below) is used to 
control the heating element so that the bowl is maintained at the desired 
popping temperature for the remaining cycles of operation of the device. 
After the desired temperature is initially achieved, corn is then 
provisioned into the heated kettle through funnel 513 and outlet 514. 
Popcorn is premixed with salt to taste and placed into the entry of funnel 
513, whereupon gravity propels the popcorn kernels with sufficient 
velocity that they enter the kettle with essentially no spillage. Corn 
mixed with salt can be placed in the funnel entry either by manual means 
or by automatic means, as disclosed in U.S. Pat. No. 5,035,173. Next 
kettle lid 520 is lowered into contact with the kettle, and cooking oil is 
provisioned into the kettle through flexible tube 524 connecting with lid 
opening 525 that, in turn, penetrates lid 520. The amount of cooking oil 
injected into the kettle is chosen in accord with the amount of corn so 
that all provisioned popcorn kernels have a uniform layer of cooking oil 
upon agitation. 
After provisioning with corn mixed with salt and cooking oil, the agitator 
mechanism is engaged as the oil and corn are brought up to the popping 
temperature. Large temperature adjustments are not usually necessary since 
the kettle remains substantially at popping temperature from a previous 
cycle. As the corn pops, the expanding volume of the popped corn, first, 
reaches the top of the kettle and then expands above the kettle. This 
expanding volume of popped corn urges the kettle lid upward eventually 
reaching the position of an actuating microswitch 533. This actuation is a 
signal that the corn popping is substantially complete. Thus, the position 
of the microswitch must be chosen in accord with the amount of corn 
provisioned into the kettle so that the volume under the kettle lid when 
the lid is at the position of microswitch 533 represents substantially 
complete popping of the provisioned corn. In a preferred embodiment, the 
position of microswitch 533 is approximately 2 to 2.5 inches above the top 
of the kettle. In alternative embodiments, one of ordinary skill in the 
art can adjust the position of the microswitch 533 according to the amount 
of popcorn to be provisioned. 
When the lid position signals substantially complete popping of the 
provisioned popcorn, the lid is then further raised to the position of 
microswitch 532 and the kettle is rotated to a position in which the 
popped corn is dumped from the kettle into the display compartment of the 
display arrangement. In a preferred embodiment, this position is 
substantially upside down requiring a rotation of approximately 
180.degree.. optionally, before this rotation, the temperature control 
means can be commanded to allow the kettle to cool, although this is 
generally not necessary because it takes longer for the kettle to reheat 
to the popping temperature for the subsequent popping cycle. When the 
popped corn has been emptied, the kettle is then rotated back to its 
substantially upright position ready to begin another popping cycle. 
Rotation from a popping position to a dumping position requires sufficient 
clearance between agitator shaft 522 and kettle lid 520 in their fully 
raised position and the top of the kettle assembly in order to avoid any 
mechanical interference. This required clearance determines the required 
vertical motion of the agitator shaft and kettle lid and, thereby, the 
length of side braces 510 and 511. 
The operating steps of a popping cycle, thus, require the actuation and 
control of three separate mechanical actions: first, the kettle must be 
rotated between a popping and a dumping position; second, the agitator 
shaft and kettle lid must be raised and lowered; and third, the agitator 
mechanism must be activated. These mechanical actions are described next. 
The control means which command the mechanical actions in response to 
feedback control signals is described subsequently. 
The kettle is rotated by any suitable reversible motor of device capable of 
applying an angular force to one of the kettle's pivot shafts, and the 
kettle's position is sensed by any suitable angular position transducer 
device. The preferred embodiment of these devices is illustrated in FIG. 
5. The angular force is supplied by electric motor 555 connected through 
worm-gear speed reducer 537 to shaft 538, which bears sprocket 540. Pivot 
shaft 507, supported by journal 530, bears sprocket 541. Sprockets 540 and 
541 are connected by chain 542, whereby the angular force of motor 555 is 
coupled to kettle assembly 509. In a preferred embodiment, sprockets 540 
and 541 define an equal speed transfer. Optionally, motion dampers, such 
as rubber bumpers, can be placed to absorb any play in the rotation 
coupling components. Alternative mechanical arrangements are apparent to 
those skilled in the relevant art. In particular, motor 555 and an 
appropriate gear coupler could be mounted directly on support brace 510 
without an intermediate drive. The preferred embodiment illustrated is 
more attractive as it places these mechanical components out of sight in 
the upper compartment of the display arrangement. 
The kettle angular position transducer devices in the preferred embodiment 
comprise cam 539 attached to shaft 538 and actuating microswitch 536 and 
cam 543 attached to shaft 507 and actuating microswitch 535. Cam 543 and 
microswitch 535 are configured to produce a signal when the kettle has 
reached its dumping position, this signal being used to halt further 
rotation towards a dumping position. Cam 539 and microswitch 536 are 
configured to produce a signal when the kettle has reached its popping 
position, this latter signal being used to halt further rotation towards 
an upright position. In the preferred embodiment, both signals result from 
opening of the respective microswitches. Alternative angular position 
transducer devices are apparent to those skilled in the relevant arts. For 
example, an angular encoder attached to shaft 538 can be used in 
conjunction with conventional discrimination circuitry to produce the two 
position signals. In addition to these signals, mechanical travel limiting 
means can be used, such as a metal or rubber stop member, so that the 
rotation of the kettle can be controlled between the desired angular 
orientation. 
Second, agitator shaft 522 and kettle lid 520 are raised and lowered as one 
unit, as the kettle lid is supported by retaining ring 523 fixedly 
attached to the agitator shaft. Oil conduit 524 is flexible with 
sufficient free play to follow the motion of the kettle lid. In the 
preferred embodiment, the agitator shaft bears teeth, as indicated at 544, 
which are contacted by gear 545 for causing vertical motion of the shaft. 
A sufficient portion of the shaft is toothed so that sufficient vertical 
motion is possible by rotation of gear 545. It is necessary that these 
teeth do not form a spiral thread, as the agitator shaft must be axially 
rotated for spinning the agitator mechanism while the shaft remains in one 
vertical position in contact with coupling hub 304 of FIG. 3C. If these 
teeth formed a spiral, the agitator shaft would necessarily move out of 
contact with the coupling hub or be forced into the hub as the agitator is 
spun. Further, it is preferable that teeth 544 on the agitator shaft be of 
such a nature as to minimize any play in the vertical positioning of the 
shaft. For example, acme teeth, which are flat on both sides and the top, 
have such a play minimizing property. 
FIG. 7A illustrates in detail the relation between these elements. There is 
illustrated shaft 522 with circular, non-spiral threads 544 contacted by 
gear 545. Preferably shaft 522 has a pitch of 12 (12 threads per inch) and 
gear 545 has a pitch of 20. From this figure it is apparent how shaft 522 
can be axially rotated, as by gear 552, while remaining in contact with 
gear 545 without any tendency for vertical motion consequent to such axial 
rotation. However, if threads 544 formed a spiral, then such axial 
rotation would cause shaft 522 to move in a vertical direction. 
Alternate means for raising and lowering the agitator shaft are possible. A 
much less preferred embodiment can employ a threadless rod contacted with 
a pair of opposed friction wheels that driven to achieve vertical motion. 
The agitator shaft and kettle lid are stabilized for vertical motion by 
bushings 548 and 549, which may be of either plastic or metal. Bushing 548 
is in cross member 501. Bushing 549 passes through member 550 which is 
supported by a plurality of support rods 551. Gear 545 is driven by a 
appropriate reversible electric motor and gear reducer unit 547, which are 
partially hidden by their support bracket 546. Alternate arrangement for 
stabilizing the agitator shaft for vertical motion and for driving gear 
545 are apparent to those skilled in the relevant art and are encompassed 
within this invention even though no further mention needs to be made 
here. 
Control of vertical position requires measuring the vertical position of 
the kettle lid and agitator shaft unit. Any position transducer known in 
the art capable of operating over the extended range necessary can be 
employed. In the preferred embodiment, only three vertical positions are 
signaled: a down position in which the lid is in contact with the kettle 
and the agitator shaft is in contact with coupling hub 304 of FIG. 3C; an 
up position in which the shaft and lid are sufficiently elevated to permit 
rotation of the kettle assembly; and an intermediate position of the lid 
which indicates substantially complete popping of the popcorn provisioned 
into the kettle and wherein the shaft remains in contact with the coupling 
hub. These positions are signaled by microswitches 532, 533, and 534 
fixedly attached at appropriate positions along side brace 510. These 
switches are contacted by the kettle lid in order to generate the 
preferred position signals. 
The up position signal is used to halt further raising of the agitator 
shaft and kettle lid. The down position signal is used to halt further 
lowering of the shaft and lid. Finally, the intermediate position signal 
is used to initiate the step of the popping cycle wherein the shaft and 
the lid are raised and the popped corn is dumped from the kettle assembly. 
All microswitches used in this invention, 532, 533, 534, 535, and 536, can 
be conventional microswitches adapted to withstand the temperatures 
generated near the kettle assembly. 
Finally, agitator shaft 522 in the down position and in contact with 
coupling hub 304 is rotated to activate the agitator assembly. When the 
shaft is down, gear 552, which is fixedly connected to the shaft, contacts 
gear 553, which is attached to motor and gear unit 554 to rotate or spin 
shaft 552. Since threads 544 do not form a spiral, shaft 522 remains in 
position as it is spun. 
FIG. 7B illustrates detail of shaft 522 in the down position. Gear 545 has 
rotated until the down position is signaled by microswitch 534, and 
consequently it is near the top of threaded portion 544 of shaft 522. Gear 
545 has been driven by reversible electric motor 601 and gear reducer 547. 
In the down position, the bottom of shaft 522 bearing pin 410 of FIG. 4A 
in contact with coupling hub 304 of FIG. 3C and the gears 552 and 553 
mesh. Thereby, when gear 553 is driven by motor and gear unit 554, rod 522 
rotates axially, which drives the agitator mechanism. 
FIG. 6 illustrates a side view, with respect to the orientation illustrated 
in FIG. 1, of the support arrangement of this invention. The visible 
physical structure includes vertical brace member 510, cross member 501, 
and horizontal support members 502. Member 502 and all elements above are 
positioned in the upper compartment of the display arrangement. All 
elements below horizontal member 502 are positioned in the display 
compartment. Kettle assembly 509 with lid 520 is supported on legs 309 and 
310 and is rotated by the chain drive comprising sprockets 540 and 541 and 
chain 542. The flexible cooking oil conduit passes from kettle lid 520 
into the upper compartment for connection to a source of cooking oil. 
Kettle rotating motor 555 and worm gear drive 537 rotate the kettle. Shaft 
raising motor 601 and gear unit 547 drive gear 545 for raising and 
lowering agitator shaft 522 and kettle lid 520. Agitator motor 554 axially 
rotates shaft 522 through gear 553. Arrangement 550 stabilizes shaft 522 
for vertical motion. 
Signal wires from the position sensing microswitches and power wires to the 
actuator motors are gathered into wiring harness 556 on their route to the 
control compartment 233 of FIG. 2. 
D. THE CONTROL MEANS 
The control means of this invention include means for kettle assembly 
temperature control, means for mechanical motion control, and means for 
automatically sequencing the steps of a popcorn popping cycle. The control 
means are contained in compartment 233 of FIG. 2. 
FIG. 8A illustrates a preferred embodiment of the temperature control 
means. Kettle heating element or elements 316 are attached to the 
underside of the popping kettle as in FIG. 3C. These may be sized from 4 
to 10 KW depending of kettle size and popping throughput required. Heating 
elements 316 are powered from power mains 801 through relay 802. This 
relay is preferably adapted to repetitive high current applications and in 
the preferred embodiment is a mercury relay. One leg of the control 
circuit for relay 802 includes normally-on thermal switch 804, which is 
one of temperature sensing means 317 in FIG. 3C. This switch is set to 
open at the maximum safe kettle temperature in order to prevent such a 
temperature from being exceeded. In the preferred embodiment the maximum 
kettle temperature is 475.degree. F. The other leg of the relay control 
includes thermocouple temperature control 806 with thermocouple 805, which 
is also one of temperature sensing means 317 in FIG. 3C. Temperature 
control 806 provides an adjustable temperature control for setting a 
desired popping temperature and optionally displaying the current kettle 
temperature. An exemplary popping temperature is between about 415.degree. 
and 430.degree. F. The temperature control can optionally also include 
outputs 807 for indicating to other control means when the kettle is at a 
desired popping or dumping temperature. The preferred temperature 
controller is a Model 1603 from Chromalox (Lavergne, Tenn.). Acting 
together with the preferred cast aluminum kettle, these elements maintain 
a safe, adjustable temperature constant to within .+-.3.degree. F. 
throughout the interior of the kettle. 
Turning now to the means for mechanical motion control, control of the 
motor actuators by the position and angular feedback signals are grouped 
into a plurality of elementary operations that can be separately 
requested. This control is accomplished by a programmed logic controller 
("PLC") such as is known in the art. The feedback microswitch signals are 
input to the controller which in turn outputs power to the motors, perhaps 
through relays or solid state switches if required. The preferred PLC is 
Model C40K-CDRA from the Omron Corp. 
FIG. 8B lists these elementary operations and indicates how the PLC 
actuates the motors and responds to the feedback signals. For example, 
when the KETTLE-DUMP operation is requested, the PLC actuates kettle 
rotation motor 555 in such a direction so that it cause the kettle 
assembly to rotate from a popping position in a clockwise direction in the 
view of FIG. 6 until microswitch 535 actuated by cam 543 on shaft 507 
generates a signal. This signal indicated that the kettle assembly has 
reached a dumping position, which is a substantially upside down position. 
Requesting the KETTLE-FORWARD, by contrast, causes the PLC to activate 
motor 555 in a reverse direction until microswitch 536 activated by cam 
539 on shaft 538 generates a signal, which signal indicates that kettle 
assembly has reached a substantially upright popping position. 
A further function of the PLC is to automatically sequence these elementary 
operations in order to fully automatically execute a corn popping cycle. 
FIG. 8C illustrates an exemplary automatic sequence of these elementary 
operations for a complete popping cycle. For automatic execution, an 
operator would provision the proper amount of corn and then request an 
automatic cycle. No further intervention in the operation of the machine 
is necessary. If the optional temperature checking step were omitted from 
the sequence of FIG. 8C, the operator would also have to manually check 
and adjust the kettle temperature. 
In the case of manual sequencing, an operator would have to manually 
request each of the eleven operations listed in the order listed. This may 
be used for certain situations when high production automatic operation is 
not necessary. 
This invention is adaptable to alternative control means of equivalent 
function. In particular, a simple microprocessor with associated 
interfacing circuity is more than adequate to fully control all elements 
of this apparatus. 
FIG. 9 illustrates control panel 106 by which an operator of this invention 
interacts with the control means of this invention to request the 
operations previously described and receive status on the operation of the 
corn popping apparatus of this invention. Switch and light 903 is the 
master power on/off. Row 917 is a row of indicator lights, and row 918 is 
a row of push buttons. Each of the seven pairs of one button and one 
light--910, 911, 912, 913, 914, 915, and 916--correspond to one of the 
elementary operations illustrated in FIG. 8B. The button requests the 
corresponding elementary operation and the light glows to indicate the 
operation is in progress. During automated operation, each light is lit in 
sequence as the steps are conducted. When manual operation is conducted, 
the lights are lit as the button is manually pushed and operation begins. 
Key switch 920 has two positions: a manual position and an automatic 
position. In the manual position, manual indicator light 909 is 
illuminated, and request buttons 918 are activated for manual control of 
the individual elementary operations of the corn popper. In the automatic 
position, automatic indicator light 904 is illuminated, and request 
buttons are not active to request elementary operations. Indicator lights 
917 remain active for monitoring the progress of a popping cycle. However, 
automatic cycle request switch and light 905 is activated. Depressing this 
switch requests performance of a popping cycle according to the sequence 
illustrated in FIG. 8C. During the cycle this light is illuminated, and 
the individual lights 917 are illuminated according to the cycle step 
being performed. 
Further controls include temperature controller 806, which in turn includes 
a display for the current kettle temperature 902 and means 921 for 
temperature adjustment and kettle heating control. The temperature 
controller can be either automatically controlled from the PLC or manually 
controlled by an operator. Switches 906, 907, and 908 control associated 
devices, such as display compartment lighting and warming the contained 
popped popcorn. 
In this manner, an operator of this invention is able to fully control the 
operation of the invention in either an automatic or manual manner and to 
monitor the progress of corn popping. The key switch provides added 
security in that in can be used to prevent unskilled operators for 
operating the invention in a perhaps dangerous or destructive fashion. 
Alternative arrangements of lights and switches can be adapted to this 
invention. In particular all indicators could be displayed on an LCD 
screen, and all input could be provided through a keypad. 
I. SPECIFIC EMBODIMENTS, CITATION OF REFERENCES 
The present invention is not to be limited in scope by the specific 
embodiments described herein. Indeed, various modifications of the 
invention in addition to those described herein will become apparent to 
those skilled in the art from the foregoing description and accompanying 
figures. Such modifications are intended to fall within the scope of the 
appended claims. 
Various publications are cited herein, the disclosures of which are 
incorporated by reference in their entireties.