Note: Descriptions are shown in the official language in which they were submitted.
~ 1 7~936
The present invention relates to a latch for locking
a door in a closed position, and in particular to a motorized
oven door securing latch used to preclude access to a self-
cleaning domestic range oven undergoing a high temperature
pyrolytic cleaning cycle.
This is a division of co-pending Canadian patent
application Serial No. 401,338, filed on April 20, 1982.
Motorized self-cleaning oven door latches are well
known in the art as represented by U.S. patent 3,859,979 to
Gilliom and U.S. reissue patent RE 27,545 to Guy. Latches
of the type illustrated by these patents include a rotary
motor mounted at a rearward portion of the range body above
the oven chamber and a reciprocating latch hook at a forward
portion of the range body, the latch hook being engageable
with a keeper fixed to the closed oven door.
To effect reciprocating movement of the latch into
and out of engagement with the keeper, a translationally
movable, longitudinal member is provided between the motor
means and the latch hook.
In U~S. patent 3,859,979, the longitudinal member
is a latching rod motor driven back and forth along its
axis by an eccentric mount in reciprocating fashion to and
away from the oven door while being cocked from side to
side as it mo~es with a cam rivet to effect door latching
and unlatching. In U.S. patent RE 27,545, an eccentric drive
arrangement moves a latch rod back and forth along its axis
in reciprocating fashion to effect latching and unlatching
of a latch member with an associated oven door.
3 6
In both of the above-noted prior art devices, it
is necessary to convert the rotational movement of an
accompanying rotary drive motor into translational motion
to effect reciprocating movement of the latch rods. The
resultant mechanisms are necessarily complex and, as a
result of their complexity, are high in cost. Since the
domestic appliance business is extremely cost competitive,
and since long-term durability is a major factor in appliance
design, there is great need for a less costly and simpler
motorized latch mechanism to replace mechanisms of the type
illustrated by the above-noted patents.
Further, the user control of such motorized latches
should be simple, straightforward, and of a fail-safe
nature to provide for a hazard-free oven cleaning operation.
Multiple control manipulations performed by the user in a
complex sequence to effect door latching should be avoided
without risking safety.
It is the purpose of the present invention to meet
all the criteria noted above with regard to a more ideal
motorized oven door latch and control of the same.
The present invention resides in a domestic range
having a body including an outwardly opening, pyrolytic
self-cleaning oyen chamber~ electrical heating means supplying
heating energy into the oven chamber, a hinge-mounted oven
door supported by the body and movable from an open to
a closed position to preclude access to the oven, and a
motorized oven door latch mechanism for locking the oven
door in a closed position. A control circuit is provided
for actuating the motorized latch mechanism and includes an
oven thermostat having a single control knob rotatable
between full clockwise and full counterclockwise end posi-
tions, the control knob having a plurality of oven tempera-
ture positions and a high temperature pyrolytic oven cleaning
1 J 70936
position located at one of the end positions. The thermostat
includes a pair of contacts as the sole means for applying
power directly to the motorized latch to effect door locking
when the oven door is closed. The contacts are closed to
apply the power to the motorized latch only when the control
knob is at the cleaning position.
A fuller understanding of the invention may be had
by referring to the following description and claims, taken
in conjunction with the accompanying drawing.
~ 1 7~936
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevational view of a domestic
range with portions cut away, the range including a
pyrolytic-type self-cleaning oven and a motorized oven door
latch in accordance with the present invention;
FIG. 2 is a sectional view of the front portion of
the oven door latch illustrated in FIG. l;
FIG. -3 iS a sectional view of the rearward portion
of the oven door latch illustrated in FIG. l;
FIGS. 4, 5, and 6 illustrate the movement of a cam
member carried by the drive shaft of a motor actuating the
latch mechanism, the cam member sequentially actuating switch
means to effect desired closing and opening sequences of the
latch;
FIG. 7 is a perspective view of a portion of the
oven door having a cam surface providing member engaged with
a latch hook portion of the latch mechanism;
FIGS. 8 and 9 are elevational and cross-sectional
views, respeetively, of the eam surfaee providing member as
illustrated in FIG. 7; and
FIG. 10 is a control eircuit in accordance with the
present invention for regulating the latching and unlatching
of the oven door.
I ~ 70935
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
. . _ . _ _
With reference to FIG. 1, there is illustrated a
conventional domestic range of the free~standing type, in-
cluding a pyrolytic self-cleaning oven, the range being
equipped with a motorized oven door latch in accordance with
the present invention. The range includes a four-sided range
cabinet or body 10, preferably formed of enameled sheet metal
and internal frame members assembled around an oven cavity
18. The body 10 supports a cooking platform or burner sur-
face member 12, which in turn supports a plurality of surface
heating units or burners 11 of the electric resistance or gas
heating type. Typically, four burners 11 (only two shown)
are supported by the surface 12, the burners being spaced
from each other to form a rectangul-ar pattern, wherein a pair
of back burners are provided along with a pair of forward
burners. Extending upwardly from the back edge of the burner
surface 12 is a control panel 14 which houses user-actuated
controls such as an oven thermostat control, an oven function
selector switch, and a timer for cycling the oven on and off
over a desired time period.
The forward wall 13a of the range body 10 includes a
pair of rectangular apertures, the lower aperture receiving a
conventional cooking utensil storage drawer 16, while an
upper aperture permits user access to the self-cleaning oven
cavity 18. The access opening of the cavity 18 is closed by
an outwardly opening, hinge-mounted oven door 20 swingable
from a vertical closed position to an open horizontal posi-
tion on a conventional hinge means 22. A handle 21 located
at the top edge of the door allows the user to position the
door at a partially open bro''il'position or a~ a fully opened
position against the biasing effect of a spring-loaded detent
type oven door hinge member 24.
1 1 70936
In a known manner, the oven cavity 18 can be highly
heated to a temperature in excess of 750 F, wherein the
walls of the oven chamber or cavity 18 are self-cleaned by
pyrolytic action. Such a phenomenon is more fully detailed
in U.S. patent 3,121,158 to Hurko, the entirety of which is
herein incorporated by reference. During a pyrolytic clean-
ing cycle, it is imperative that the oven user not be able to
open the oven door 20, since the rapid influx of oxygen-rich
air into the cavity 18 could result in an explosion of com-
bustible gases generated therein, or hot, noncombustible
gases escaping from the oven could injure the user.
- To provide such oven door locking, a latch mechanism
in accordance with the present invention is provided to lock
the oven door 20 in its closed position as illustrated in
FIG. 1.
The latch mechanism includes a rotary motor means 30
including appropriate reduction gearing, the motor 30 rotat-
ing an elongated latch hook rod 32 extending through a plur-
ality of apertures in a sheet metal formed superstructure 13
constituting a ~ortion of the range body 10. The rod 32 is
generally of circular cross section and extends from the back
portion of the range, where the motor 30 is mounted, to the
forward portion of the range wherein the distal hook end of
the rod can engage and disengage with the oven door 20 at a
hook/keeper interface area 40. Also extending from the front
of the range to its rearward portion is a door position moni-
toring rod 15 which opens and closes a switch when the rod's
distal end abuts and is moved into the range body by the
upper end portion of the closed oven door 20.
Turning to FIG. 2, there is illustrated in greater
detail the hook/keeper interface area 40 discussed earlier
with regard to FIG. 1. The door 20 includes an outer door
panel 26 and an inner door panel 27, the panels being spaced
I 1 70936
from each other to receive a plurality of conventional glass
panels 25 which thermally insulate the outer portions of the
oven door window area from the highly heated oven chamber 1
undergoing pyrolytic cleaning. An inner door window frame
27a assists in retaining the innermost glass panel 25 in its
proper position.
Positioned between the panels 26 and 27 at the upper
intermediate portion of the door 20 is a keeper 70 which is
secured to the upper distal end of the bottom-hinged oven
door 20 in a manner to be subsequently discussed in greater
detail.
The keeper 70 i5` generally of a U-shaped cross sec~
tion having an outside leg 72, a horizontally extending bot-
tom shelf portion 73, and an upwardly extending inside leg
74. At the lower center portion of the inward leg 74, there
is provided an aperture or cutout area having a moon-shaped
lower lip constit~ting a cam surface 75 upon which an L-
shaped, radially extending hooked end 33 o the rod 32 will
ride during a locking and unlocking cycle of the door locking
mechanism. Movement of the rod 32 back and forth along its
axis is only restrained at one point, such restraining being
provided by axial compression of a biasing means 50. In
assembling the latching rcd 32 in its position within the
range body 10, an aperture is provided in the forward edge
12a of the burner surface member 12, such aperture being
preferably centered at a position located intermediate the
left and right edges of the oven door 20. An appropriately
sized aperture through the forward edge 12a is also provided
to permit the forward distal end of the door position moni-
toring rod 15 to project forward of the wall 12a for engage-
ment in abutting fashion with the top edge of the panel 27 as
the oven door 20 is closed and opened. A tubular bushing 51
is fixed in position on the hook end portion of the rod 32 by
1 1 70936
an appropriate retaining pin 32a extending diametrically
~hrough an appropriate hole drilled through the rod. The
forward end of the tubular bushing 51 includes a flange 52 of
a diameter greater than the aperture through which the rod 32
projects through the front wall 12a such that the flange 52
precludes the bushing 51, and thus the rod 32, from being
pulled into the upper portion of the range body 10, the
flange 52 in e~fect forming a stop. On the inner side of the
wall 12a, there is provided a conventional washer 53 slidable
onto the tubular bushing 51. A biasing spring 54 of the
helical type is sandwiched between the washer 53 and a split
ring retaining clip 55 retained in position on the bushing 51
is an appropriate circumferentially extending groove. The
spring 54 can thereby be compressed to bias and force the
latch rod 32 toward the back portion of the range, which sup-
ports the motor means 30 (FIG. 1).
In FIG. 2, the oven door 20 is illustrated at its
closed position, with the hook end 33 of the latch rod 32
fully engaging the cam surface 75 at its highest cam height
to tightly retain the oven door 20 in a locked condition
wherein a conventional oven door seal 23 is slightly com-
pressed to seal the oven door 20 relative to the range body.
Such an arrangement precludes uncontrolled inlet of air into
the oven chamber 18 undergoing the pyrolytic cleaning cycle.
Further, the walls, such as the top wall 18a, defining the
oven chamber are sealed against oven wall supporting portions
of the range body 10 by an appropriate seal 18b extending
peripherally about the forward, rectangular edge of the oven
chamber defing walls. To provide adequate compression of the
oven door seal 23, the cam surface 75 as illustrated is
ramped to or from a high cam point to gradually increase and
then decrease its distance away from the forward edge 12a of
the range body 10. As the rod 32 is rotated on its longitu-
dinal axis from a starting position wherein the generally
I 1 70936
radially extending hook portion 33 extends upwardly, the
inner face 33a of the hook portion 33 will ride the cam sur-
face 75 toward its high point to more fully compress the
spring 54, the spring 54 exerting a counterpulling force on
the keeper 70, which is fixed to the horizontally extending
longitudinal member 60 supported only at its ends, as shown
in FIG. 7.
With the oven door in its locked position as illus_
trated in FIG. 2, the spring 54 is compressed, as illus-
trated, with the rod 32 being pulled outwardly away from the
range body towards engagement with the high point of the cam
surface 75 provided by the keeper 70~ which will place the
member 60 in torsion. In pulling the rod outwardly from
within the range body, the flange 52 will end up in a spaced
position slightly away from the forward edge 12a as shown,
the distance of such space indicating the amount of addi-
tional compression placed on the spring 54. It is also noted
that the upper end of the legs 74 of the keeper 70 rides
against and abuts the inner section of the door panel 27 to
limit the amount of torsion placed on the member 60. With
the oven door at its locked position as illustrated in FIG.
2, preferably the spring 54 is fully compressed to provide a
rigid structure precluding further movement of the rod out-
wardly from within the range body. Also, the upper edge of
the legs 74 tightly engages and locks in place relative to
the inner surface of the panel 27 to limit torsion of the
member 60. In such a condition, the user in gripping the
handle 21 cannot open the oven door. ThUS, in accordance
with the present invention, by simple rotation of the rod 32,
an effective, rigid locking of the door at its fully closed
position is provided, with adequate compression of the seal
23 precluding hazardous air inlet to the pyrolytically heated
oven chamber 18.
i 1 70936
Turning to FIG. 3, there is illustrated in greater
detail a means for rotationally driving the latch rod 32.
The motor means 30, which includes appropriate reduction
gearing of a conventional nature, is fixed to a motor support
member or plate 29, which in turn is solidly fastened to a
rigid structural support portion of the range body 10. The
motor means 30 is preferably mounted as illustrated to the
back portion of the plate 29, which has an aperture through
which a motor drive shaft 31 extends. The drive shaft 31 is
fixed to a coupling 34 having an axially extending, noncircu-
lar or semicircular aperture or bore which slidingly receives
a correspondingly noncircular or semicircular cross-sectional
end 32b of the rod 32, the shaft 31, rod 32, and coupling 34
being coaxially rotational relative to each other. The end
32b is received within the coupling 34 and rotatably locked d
relative thereto, while permitting limited axial movement or
sliding of the shaft end 32b into and out of coupling 34,
wherein a variable lost motion space ~4a is provided. With
reference to FIGS. 2 and 3, it can be seen that the rod 32a
is axially held in biased position by the biasing means 50
which permits the rod to move outwardly toward the door
during locking engagement of the hook portion 33 with the cam
surface 75. Such a structure, wherein the end 32b of the rod
32 can slide into and out of the coupling 34, also permits
the latch mechanism to compensate and adjust for thermal
expansion and contraction of the range body 10 and related
structures, particularly during a high self-cleaning cycle.
It is noted that the space 34a as illustrated in FIG. 3 must
at least be equal to the space between the flange 52 (FIG. 2)
and the front of the oven wall 12a wherein disengagement of
the hooked end 33 of the latch rod 32 from the high point of
the cam surface 75 permits the spring 54 to snap the latch
rod back into the axially fixed coupling 34, wherein the
flange 52 of the bushing 51 engages and abuts the front wall
1 1 70936
portion 12a about the latch rod aperture receiving the bush-
ing 51.
With further reference to FIG. 3, a rotatable cam
member 35 is fixed to the coupling 34, the cam member actuat-
ing a pair of microswitches, to be discussed subsequently.
It is also noted that the door position monitoring rod 15 has
its rearward end fixed to a spring member of a door-mounted
microswitch lSa, which functions in a known manner within the
control circuitry of the oven to, for example, turn on and
off a light within the oven chamber 18.
With reference to FIGS. 7, 8, and 9, there is illus-
trated in greater detail the positioning and construction of
the door keeper 70.
The longitudinal member 60 is preferably constituted
by a horizontally extending piece of steel angle iron. The
ends of the member 60 are fixed to the upper edge of the
inner door panel 27 by, for example, pairs of fasteners such
as rivets or spot welds 61. The center portion of the member
60 is thus free to twist in a limited fashion on its longitu-
dinal axis if loaded by a torsion-providing force. Such a
twisting force is provided by mounting of the keeper 70 to
the vertically extending leg of the member 60, such mounting
being accomplished by a pair of fasteners such as rivets or
spot welds 71. It can be seen that the moon-shaped cam sur-
face 75 provided by the upwardly extending leg 74 (comprised
of two parallel portions as illustrated) is radially spaced
from the longitudinal axis of the member 60 wherein a lever
action pulling force on the cam surface 75 provided by the
rotating spring-biased latch rod 32 will cause a torsioning
or twisting force to be applied to the member 60, as indi-
cated by force arrow 76. The amount of torsion is controlled
by the abutment of the upper edge of the leg portion 74 of
the keeper 70 with the inner portion of the inner wall 27 of
the oven door 20, as discussed earlier with regard to FIG. 2.
1 J 7~936
~ ith particular reference to FIGS. 8 and 9, the
keeper 70 is preferably formed by bending a precut, flat
sheet of steel into the desired shape, wherein the moon-
shaped cam surface 75 is provided at the lower portion of a
U-shaped cutout section of the upper leg 74. Thus, the tor-
sion force on the member 60 will tend to generate a pulling
force on the latch rod 32, which in turn is subjected to an
opposed pulling force by the spring 54 (see FI~. 2), such
forces causing the oven door to be tightly engaged with the
range body to seal it during a pyrolytic cleaning operation.
With reference to FIGS. 4, 5, and 6, there is illus-
trated in greater detail a cam member 35 at various rotation-
al positions relative to a latch motor microswitch 204 and an
interlock microswitch 206, both of such switches being of the
single-pole, double-throw type. The general function of the
switches 204, 206 in relation to the rotating cam member 35
is well known in the art, as described by earlier-noted U.S.
Reissue patent 27,545, assigned to the assignee of the pres-
ent invention, such patent being herein incorporated in its
entirety by reference. In general, as viewed from the front
of the range, the switch 204 opens and closes to permit ener-
gization of the motor 30 for a period of time which will only
result in 180 degrees of rotation of the latch rod 32. Thus,
the cam member outer peripheral surface 35a engages with a
switch button 204a for the switch 204 to move it in and out
of a motor-actuating position for~only approximately 180
degrees of its rotation. In a similar manner, the switch 206
actuated by a switch button 206a engageable with the outer
peripheral cam surface of the cam member 35 is opened and
closed on each 180 degrees of latch rod rotation in a manner
to preclude inadvertent pyrolytic hea~ing of the oven under a
door-open condition.
~ clear understanding of the function of switches
204 and 206 as they relate to locking and unlocking rotation
I 1 70936
of the latch rod 32 as discussed earlier may be had by refer-
ring to FIG. 10, which discloses, in accordance with the
present invention, a simple means for locking the oven door.
Reference to the earlier-incorporated U.S. Reissue patent
27,545 is also made as illustrating a typical self-cleaning
oven sequPnce but for the departure of the invention from
such prior art teachings as noted below. It is noted that
while FIG. 10 is directed to a resistance type heating ele-
ment oven, it is clearly contemplated that the present invention
is also intended for gas-heated, self-cleaning ovens or other
equivalents wherein locking of a door during a period of oven
operation is desired.
The above-described latch mechanism is also disclosed
and is claimed in parent application Serial No. 401,338.
Turning specifically to FIG. 10, in a conventional
manner, a pair of power lines 100, 101 and a neutral line
103 are provided to the oven (conventional commercial power,
e.g., 220 VAC, 60 Hz) control circuit. In a simple form,
the oven heating elements typically include a single bake
oven heating element 106 and a broil oven heating element
108. The circuit of FIG. 10 is also shown to include a
conventional smoke eliminator catàlytic element 110, which
functions in a known manner to minimize smoke that escapes
from the oven cavity 18 (FIG. 1) during a self-cleaning opera-
tion via a conventional vent outlet (not shown). A conven-
tional selector switch 20Q having plural sets of contacts
functions in a known manner to permit various operating
cycles of the oven~ including a self-cleaning cycle. The
control circuit of FIG, 10 also has a conventional oven timer
202, a conventional door lock indicating light 102, and a
conventional oven pilot light 104.
In accordance with the present invention, an oven
thermostat 300 is proyided, the thermostat 300 having a
single operating knob 302 rotatable from a counterclockwise
"warm" position in a full clockwise "clean" position (as
illustrated), the knob being engageable at various positions,
-13 -
.. 1 1 7~9~6
14
and in particular at the clean position, with a detent means
of conventional design. It can be seen that in rotating the
knob 302 clockwise from its "warm" position to its "clean"
position, a gradually increasing range of oven temperat~re in
the bake mode i5 provided with the broil element 108 alone
being at its full "on" condition for maximum heating when the
knob 302 is at the indicated broil position (BR). In addi-
tion to adjustable thermostat elements 306,308 of a known
type for regulating oven temperature, the thermostat 300
includes a door unlock disable thermostatic switch element
307. In accordance with the invention, a set of single-pole,
double-throw contact switch means 309 are provided ~or actua-
tion by associated known mechanical elements actuated in turn
by rotation of the knob 302 to and away from its full clock-
wise end position (clean). It is noted that the temperature
at which the thermostatic elements 306, 308 concurrently open
and close is determined by the position of the knob 302,
while thermostatic element 307 is not adjustable by rotation
of such knob but, rather, will switch to a nonconducting con-
dition as a predetermined temperature which it senses is
exceeded.
With the knob 302 at its "warm" position (full
counterclockwise rotation), a movable contact 309a of the
- switch means 309 is spaced from a fixed cleaning contact 309b
and is ;n contact with a normal baking cycle contact 309c.
When the knob 302 is rotated fully clockwise to its "clean"
position (full clockwise rotation), element 306 being in a
closed conducting condition, a suitable mechanical member
moves the movable contact 309a into engagement with the con-
tact 309b (out of engagement with control 309c) to actuate
the earlier-discussed motorized latch of the oven door
regardless of the setting of the selector switch 200 or the
timer 202. Such a procedure greatly simplifies locking and
unlocking of the door.
I 1 7~36
lS
A locking and unlocking sequence will now be dis-
cussed, it being understood that tlle starting point for such
a sequence is in a door-unlock condition with the switches
204 and 206 in position as illustrated in FIG. 10.
Upon rotation of the oven thermostat knob 302 to the
~Iclean~ position, contacts 309a and 309b are closed, with
thermostat means 306 and 308 being mechanically adjusted to a
high-temperature, self-cleaning condition. Power from line
100 is provided via thermostat means 306 and contact pair
309a, 309b to a ~irst lock energization line 400 which pro-
vides power to the lock motor 30 via a fixed contact 204b to
a movable contact 204a o the latch motor switch 204. SUch
applied power to the motor 30 is returned to the neutral line
103 via a return line 402 which is tied to the door monitor
switch 15, illustrated in its door closed position. Thus,
the motor 30 is energized and turns the latch rod 32 (see
FIG. 3) for approximately 180 degrees of rotation wherein the
latch hook rod tightly engages the cam surface 75 as dis-
cussed earlier with regard to FIGS. 1-3, the movable contact
member 204a then being switched by the cam surface 35a (FIG.
6) to its other fixed contact 204c. This sequence is known
in the art, and is more fully discussed in the earlier-
incorporated U.S. reissue patent RE 25,545.
At this point, the motor 30 will be de-energized,
since an alternate motor energizing line 500 connected to the
terminal 309c of door lock switch 309 is isolated from the
power line 100. It is also noted that the interlocking
switch 206 has moved from the position illustrated in FIG. 1
to a second cleaning position wherein the movable contact
206a engages a clean mode fixed contact 206b and disengages
from a normal bake mode fixed contact 206c to precondition
the oven circuit for a self-cleaning operation. The inter-
lock switch 206 further precludes high heating of the ele-
ments to effect oven cleaning where the oven door is not
- I 1 70~3~
16
locked as indicated by failure of the cam member 35 (FIGS. 4,
5, and 6) to switch movable contact 206a from fixed contact
206c to fixed contact 206b. Again, it is noted that such
function of switch 206 is known in the art as illustrated by
the earlier-noted U.S. reissue patent.
To effect unlatching of the oven door at the end of
a self-cleaning cycle, thermostat means 307 must be closed,
indicating that the oven temperature has dropped below a
hazardous level wherein oven door opening is allowable. In
manually moving the knob 302 from its clean position counter-
clockwise through its various bake positions, the movable
contact 309a is swung into contact with fixed contact 309c
(where it nor~ally remains except at the "clean" position)
wherein line 500 is energiæed to power the motor 30 for
another 180 degrees of unlocking rotation.
It can be seen that a control circuit is provided
wherein the contacts 309a and 309c are in electrical series
relationship with the oven thermostat 306, which is operable
at a nonconducting or fully conducting state, the thermostat
means regulating the oven temperature in both a normal oven
heating mode lbake and broil) and a high temperature cleaning
mode, power to the motorized latch mechanism to effect oven
door locking being provided solely by the thermostat means
wherein the thermostat means is always in a fully conducting
condition at or below a predetermined pyrolytic cleaning tem-
perature (e.g., 750 F) within the oven when the control
knob is at a clean position.
Unlike prior art motorized oven door latch control
circuits, the selector switch 200 and the timer 202 have no
part to play in effecting oven door latching and unlatching,
thus presenting the oven user with a simple and straightfor-
ward means of locking and unlocking the oven door. The se-
lector 200 and the timer 202 simply function as means for
initiating and setting the duration of a self-cleaning cycle.
1 ~ 70936
17
as is known in the art. Further, the door control circuitry
illustrated in FIG. 10 is of a simpler design than previous
motorized latch control circuits. Finally, the door lock
circuit of FIG. 10, while being simpler, still provides for
nonhazardous operation of the oven wherein conventional
fail-safe means (e.g., interlock switch 206 and door monitor
switch 15a) are provided to preclude energization of the oven
into a self-cleaning mode without proper locking of the oven
door. While only the door lock circuit portions of FIG. 10
have been specifically discussed as relevant to the present
invention, the operation and function of other illustrated
components of FIG. 10 will be apparent to one skilled in the
art.
Although the preferred embodiments of this invention
have been shown and described, it should be understood that
various modifications and rearrangements of parts may be
resorted to without departing from the scope of the invention
as disclosed and claimed herein.
