U.S. patent number 3,706,863 [Application Number 05/071,620] was granted by the patent office on 1972-12-19 for multiple switch assembly for vending machine selecting apparatus with improved master switch control.
This patent grant is currently assigned to The Seeburg Corporation. Invention is credited to Leon R. Britton, Joseph K. Semerjian.
United States Patent |
3,706,863 |
Britton , et al. |
December 19, 1972 |
MULTIPLE SWITCH ASSEMBLY FOR VENDING MACHINE SELECTING APPARATUS
WITH IMPROVED MASTER SWITCH CONTROL
Abstract
A selecting apparatus includes a plurality of selector input
switches, each of which is representative of a character utilized
to identify selections in a vending machine and each of which is
individually actuatable by an associated actuator. Additional input
switches are provided for supplemental switching functions. The
actuators are adapted for displacement beyond the contact mating
position in order to close a common master switch, which controls
energization of the circuits containing the selector input
switches, after the input switch has been closed. Each input switch
actuator has a spring-biased contact holder and is assembled by
utilizing a restraining collar with a latching member to position
the spring.
Inventors: |
Britton; Leon R. (Chicago,
IL), Semerjian; Joseph K. (Franklin Park, IL) |
Assignee: |
The Seeburg Corporation
(Chicago, IL)
|
Family
ID: |
22102487 |
Appl.
No.: |
05/071,620 |
Filed: |
September 11, 1970 |
Current U.S.
Class: |
200/5R;
200/5E |
Current CPC
Class: |
H01H
13/74 (20130101); G07F 17/305 (20130101); H01H
9/0066 (20130101) |
Current International
Class: |
H01H
13/70 (20060101); G07F 17/30 (20060101); H01H
13/74 (20060101); G07F 17/00 (20060101); H01h
009/20 () |
Field of
Search: |
;200/5R,5A,5E,16A,159,160 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Scott; J. R.
Claims
We claim:
1. Vending machine selecting apparatus comprising:
a plurality of selector input switches, each of said input switches
representing a vend selection identifying character;
a master switch controlling energization of circuits containing
said selector input switches;
master switch actuating means adapted to actuate the master switch
after and in response to the actuation of any input switch; and
selector input switch actuating means for each of said selector
input switches, each of said input switch actuating means being
adapted to first actuate its respective selector input switch and
then to activate the master switch actuating means after actuation
of its respective selector input switch,
whereby the circuit containing a selector input switch is not
energized until after the associated selector input switch is
actuated.
2. Selecting apparatus as claimed in claim 1 wherein:
said input switch actuating means each comprises a longitudinally
reciprocable plunger having bridging contacts of the associated
selector input switch thereon; and
each of said selector input switches further comprises a pair of
stationary contacts mounted on a fixed surface and arranged to be
electrically interconnected by said bridging contacts upon
reciprocation of the associated plunger.
3. Selecting apparatus as claimed in claim 2 wherein each of said
plungers comprises:
a stem;
a contact holder bearing said bridging contacts mounted on said
stem and normally positioned adjacent one end of said stem, said
contact holder being reciprocably movable along the portion of said
stem away from said one end;
a collar located adjacent the other end of said stem; and
a spring positioned between said contact holder and said
collar,
whereby said spring normally biases said contact holder to the
position adjacent said one end of said stem but permits said
contact holder to be displaced away from said one end when it
engages said fixed surface.
4. Selecting apparatus as claimed in claim 3 wherein:
said stem is flat and generally rectangular and has stop means
projecting from the stem adjacent said one end thereof and a notch
formed in said stem adjacent said other end;
said stop means are adapted to limit the movement of said contact
holder toward said one end; and
a latching member is fitted into said notch in order to prevent
said collar from being forced off said other end.
5. Selecting apparatus as claimed in claim 3 wherein:
said stem is flat and generally rectangular with a pair of stop
projections located adjacent said one end of said stem and a pair
of notches formed in said stem adjacent said other end;
said stop projections are adapted to limit the movement of said
contact holder toward said one end; and
a latching member is fitted into said notches to prevent said
collar from being forced off said other end.
6. Selecting apparatus as claimed in claim 5 wherein:
said latching member comprises a generally oblong disc having an
opening formed therein comprising two offset portions, the length
of said opening where the portions overlap being slightly greater
than the width of said stem, and the width of said opening where
the portions overlap being slightly greater than the width of the
section of said stem between said notches,
whereby said latching disc may be slid over said other end of said
stem and then twisted in said notches to prevent said collar from
being removed from said stem.
7. Selecting apparatus as claimed in claim 3 wherein:
said bridging contacts comprise a resilient, bow-shaped conductor
fastened intermediate its ends to said contact holder, the outward
ends of said conductor being bent toward the fixed surface and
being positioned opposite said stationary contacts; and
said contact holder is positioned to engage the fixed surface
shortly after said bridging contacts engage said stationary
contacts when said plunger is reciprocated.
8. Selecting apparatus as claimed in claim 3 wherein:
said collar has a pair of flanges located thereon and extending in
opposite directions therefrom; and
said master switch actuating means comprises a pivotable rod
engaged by said flanges and having a thrust cam located thereon;
and
said master switch actuating means further comprises a thrust lever
engaging said master switch and actuated by said thrust cam.
9. A vending machine selecting apparatus as claimed in claim 1,
wherein, upon deactuation of each selector input switch, its
respective selector input switch actuating means is adapted to
first deactivate the master switch actuating means and thereby
deactuate the master switch before it deactuates its respective
selector input switch, whereby no current is permitted to flow
through any selector input switch at the time such switch is being
actuated or deactuated.
10. A vending machine having a switch box and selecting apparatus
comprising:
a plurality of depressable plungers projecting through a side of
the switch box;
a plurality of selector input switches mounted in the switch box,
each input switch being connected to an input circuit and being
individually actuable by an associated one of said plungers;
a master switch mounted on the switch box, said master switch being
connected to each of the input circuits so as to control the
actuation of each input circuit;
a thrust lever slidably mounted in the switch box and adapted to
actuate said master switch; and
interacting means in the switch box adapted to actuate said thrust
lever and thereby actuate said master switch in response to the
depression of any plunger for any selector input switch, said
interacting means being adapted to actuate the master switch after
actuation of the selector input switch.
11. Selecting apparatus as claimed in claim 10 wherein said input
switches are positioned in rows and said interacting means
comprise:
a plurality of treadle bars, one treadle bar positioned adjacent
each row of input switches;
a flange associated with each of said plungers;
cam means extending from each treadle bar, each of said cam mean
adapted to engage said flanges of all of said plungers associated
with said input switches in one of the rows of said input switches,
such that depression of any plunger associated with an input switch
in that row will cause said cam means to pivot the corresponding
treadle bar; and
thrust cam means extending from each of said treadle bars, said
thrust cam means being adapted to activate said thrust lever by
engaging a cam surface on said thrust lever whenever the associated
treadle bar is pivoted by depression of one of said plungers.
12. Selecting apparatus as claimed in claim 10 wherein:
bridging contacts of an associated input switch are mounted on each
of said plungers;
each input switch further comprises stationary contacts mounted on
a fixed surface and arranged to be electrically interconnected by
said bridging contacts upon reciprocation of the associated
plunger; and
each plunger comprises a stem, a contact holder reciprocably
mounted on the stem and bearing said bridging contacts, a collar
located adjacent the other end of said stem, and a spring
positioned between said contact holder and said collar,
whereby said spring normally biases said contact holder to a
position adjacent said one end of said stem but permits said
contact holder to be displaced away from said one end when it
engages said fixed surface.
13. Switching apparatus comprising:
a longitudinally reciprocable stem;
a contact holder slidably mounted on said stem and normally
positioned at one end of said stem, said contact holder being
reciprocably movable along the portion of said stem away from said
one end;
stop means on the stem to prevent the contact holder from sliding
off said one end of the stem;
bridging contacts mounted on said contact holder;
a pair of stationary contacts mounted on a fixed surface adjacent
said one end of said stem and arranged to be electrically
interconnected by said bridging contacts upon reciprocation of said
stem;
a collar fixed to the stem adjacent the other end of said stem;
and
a spring positioned between said said contact holder and said
collar,
whereby said spring normally biases said contact holder to the
position adjacent said one end of said stem but permits said
contact holder to be displaced away from said one end when said
contact holder engages the fixed surface.
14. Switching apparatus as claimed in claim 13 wherein:
said stem is flat and generally rectangular and has a pair of
notches formed in said stem adjacent said other end;
said stop means comprises a pair of stop projections located
adjacent said one end of said stem, with said stop projections
being adapted to limit the movement of said contact holder toward
said one end; and
said collar comprises a latching member fitted into said notches to
prevent said collar from being forced off said other end.
15. Switching apparatus as claimed in claim 14 wherein:
said latching member comprises a generally oblong disc having an
opening formed therein comprising two offset portions, the length
of said opening where the portions overlap being slightly greater
than the width of said stem, and the width of said opening where
the portions overlap being slightly greater than the width of the
section of said stem between said notches,
whereby said latching disc may be slid over said other end of said
stem and then twisted in said notches to prevent said collar from
being removed from said stem.
16. Switching apparatus as claimed in claim 13 wherein:
said bridging contacts comprise a resilient, bow-shaped conductor
fastened intermediate its ends to said contact holder, the outward
ends of said conductor being bent toward the fixed surface and
being positioned opposite said stationary contacts; and
said contact holder is positioned to engage the fixed surface
shortly after said bridging contacts engage said stationary
contacts when said plunger is reciprocated.
17. A vending machine selecting apparatus comprising:
a switch box having a top, a bottom, and four sides;
a circuit board mounted in said switch box parallel to said top,
said circuit board comprising a plurality of pairs of contact
points spaced a fixed distance apart, with each pair of contact
points being electrically connected to a pair of electrical
terminals on the outside of the switch box;
a plurality of flat, generally rectangular stems mounted in said
switch box, each said stem slidably passing through an opening
therefor in the top of said switch box in a direction perpendicular
thereto and extending inwardly through an opening therefor in said
circuit board and terminating in an inward end, each said stem
being individually reciprocable within said switch box from a
deactuated position, wherein the end of said stem outside said
switch box is in a raised position, to an actuated position,
wherein the end of the stem outside said switch box is in a
depressed position;
a spring mounted behind each of said openings in said circuit board
so as to engage the inward end of the stem projecting therethrough
and resiliently hold said stem in its deactuated position;
a contact holder slidably mounted on each said stem toward the
inward end thereof;
a plurality of resilient, bow-shaped bridging contacts, one
bridging contact corresponding to each pair of contacts in said
circuit board, each said bridging contact being mounted on a
contact holder at a point adjacent its corresponding pair of said
contacts in said circuit board so as to engage said contacts when
the stem associated with said contact holder and said bridging
contacts is moved from its deactuated to its actuated position;
a pair of stop projections extending from each stem at a point
adjacent the inward end of said stem so as to prevent the contact
holder on said stem from sliding off the inward end of said
stem;
a pair of notches formed in each stem, said notches being located
adjacent the outward end thereof;
a collar slidably mounted on each stem toward the outward end
thereof, each said collar having a pair of flanges extending
radially from opposite sides thereof;
an oblong latching disc mounted on each stem, each disc having an
opening formed therein comprising two offset portions, the length
of said opening where the portions overlap being slightly greater
than the width of the stem, and the width of said opening where the
portions overlap being slightly greater than the width of the
section of said stem between said notches, said disc being adapted
to be slid over the outward end of said stem on the outside of the
collar and twisted in said notches so as to prevent said collar
from being removed from said stem;
a spring mounted on each stem between said collar and said contact
holder, said spring being adapted to resiliently urge said contact
holder toward the inward end of said stem and against said stop
projections;
a master switch mounted on said switch box, said master switch
having a deactuated and an actuated position;
a thrust lever mounted in said switch box so as to be engageable
with said master switch, said thrust lever having a deactuated
position, wherein the master switch is maintained in its deactuated
position, and an actuated position, wherein the master switch is
maintained in its actuated position;
at least one pivotable rod mounted in said switch box transversely
to said thrust lever, said pivotable rod comprising cams that
extend therefrom into engagement with said flanges on said collars
so that said pivotable rod pivots whenever any stem is depressed,
said pivotable rod further comprising a thrust cam that extends
therefrom into engagement with the thrust lever, said thrust cam
being formed so as to move the thrust lever to its actuated
position whenever any stem is depressed, but only after any
bridging contacts associated with said stem have engaged their
corresponding contacts in said circuit board,
whereby the gradual depression of any stem first causes the
bridging contacts to engage the corresponding contacts in the
circuit board, and then causes the pivotable rod to move the thrust
lever to its actuated position, thereby activating the master
switch.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to a selecting apparatus for
vending machines, and more particularly this invention relates to a
switching arrangement utilized in a phonograph selecting
apparatus.
2. Description of the Prior Art
In many applications, such as coin-operated vending machines (e.g.,
coin-operated phonographs), selecting apparatus are employed in
order to permit an operator to choose any one of a number of
selections simply by pressing one or more selector buttons. The
depression of a selector button initiates an input signal, which in
turn triggers some desired machine function.
One of the deficiencies of the selecting devices of the prior art
is that switches providing a reasonable number of alternative
selections are often quite cumbersome and complex. Consequently,
such units have a high initial cost and are difficult and expensive
to service. Moreover, they take up considerable space in the system
in which they are employed. When this vending machine system is a
coin-operated phonograph or the like, where space and design
considerations are very important, the size and complexity of the
prior art selection systems has been found to be very
undesirable.
Another drawback with the selecting devices of the prior art is
especially important when the selecting devices are employed in a
system using a logic circuitry selecting mechanism. In such a
system, the signals generated by the selecting devices are impulse
signals that are received by the logic circuitry of the selection
sensing mechanism of the apparatus. Such selecting systems provide
a large number of selections and utilize little space, but the
impulse signals are of such a nature that they are easily and often
duplicated extraneously in the system (as by starting the apparatus
or by an electrical malfunction or through some external force,
such as jostling the machine), without the depression of an
appropriate signal button, so that the machine is placed into
operation when no selection has been made. This, of course, results
in a direct economic loss to the owner of the machine in case of
coin-operated phonographs and the like, not to mention the
inconvenience and aggravation in having such a system commence
operation on its own at various times. The prior art selecting
devices provide no means for insuring that genuine selections are
the only signals transmitted from the selecting apparatus to the
sensing mechanism of a vending machine, so that logic circuitry
sensing mechanisms have heretofore been plagued with the problem of
undesired vends occuring through extraneous circuit signals.
Another deficiency in the prior art selector switches is that the
selector input switches have not been entirely satisfactory. Dirt
and grease eventually build up on any switch contacts, thereby
impairing the operation of the switch, and no inherent means are
provided in the switches of the prior art to remove this dust and
grease without disassembly of the switch apparatus.
Still another disadvantage of prior art selecting devices is that
if the selector switches are utilized to directly open and close
current-carrying circuits, the switches have to have a high power
capability. In addition, making and breaking current-carrying
circuits shortens the life and causes contact problems for even
heavy duty switches.
Still a further disadvantage of prior art switching arrangements
involves the ever-present vending machine problem of "cheating".
Since most switching arrangements previously utilized have
electrically energized circuits containing the selector switches,
unearned vends can frequently be obtained by tampering with the
circuits. Also, it is frequently possible to obtain multiple
selections by getting more than one choice registered during the
time that a credit control permits the registering of a choice.
In order to obviate the above-discussed deficiencies in the prior
art selector switch systems, the present invention was evolved.
SUMMARY OF THE INVENTION
In accordance with the present invention, an improved selecting
apparatus for vending machines and the like comprises a plurality
of selector input switches that are individually actuatable by
means of depressable plungers and a master switch that controls the
energization of circuits containing the selector input switches.
The master switch is actuated by means of a master switch actuator
comprising a thrust lever and cam apparatus that interacts with the
plungers, such that the depression of any plunger first actuates
its respective selector input switch and then actuates the master
switch, thereby completing the energization of the circuit.
A selecting apparatus constructed in accordance with the present
invention obviates all of the deficiencies of the prior art
switching devices discussed above. FIrst, the apparatus of the
present invention is small, simple, and inexpensive (the whole
assembly being only slightly larger than a pack of cigarettes), yet
it can be adapted to provide up to one thousand separate selections
with only ten selector switches when employed in a vending machine
using a logic circuitry selection system of the type disclosed in a
co-pending United States patent application of Thomas P. Jachinek
and Thomas A. Murrell entitled "Selecting Apparatus and Method for
Phonograph," U.S. Pat. application, Ser. No. 862,624, filed Sept.
11, 1969, and assigned to the same assignees as the present
application.
The master switch feature of the present invention makes the
subject selecting apparatus particularly well adapted for use in
such logic circuitry selection systems, because the master switch
obviates one of the most serious problems with such systems,
namely, the problem of extraneous circuit signals producing
undesired vends.
In such a system, extraneous signals are eliminated by providing an
AND gate at the input to the selection sensing mechanism, with one
input of the AND gate being connected to the selector input switch
circuit and the other input being connected to a separate master
switch circuit. When a plunger is depressed and the master switch
and a selector input switch are actuated, separate input signals
are generated in each circuit and both signals appear at the inputs
to the AND gate simultaneously, so that the AND gate transmits an
appropriate signal to the selection sensing mechanism.
However, when an extraneous signal arises in either the input
switch or master switch circuit, that signal appears at only one of
the inputs of the AND gate, so no signal is transmitted to the
selection system. Only in the rare situation when two extraneous
signals appear simultaneously in the input switch and master switch
circuits will an improper signal be transmitted to the selection
system, and it has been found in practice that such duplicate
signals almost never arise extraneously and are difficult to
impossible to induce by cheating.
Another advantage of the present invention is that the master
switch feature virtually eliminates arcing between the contact
points of the selector input switches when the switches are opened
and closed, and this prolongs contact life substantially. In
addition to providing a means for supplying an independent signal
at an AND gate, the master switch also controls the energization of
the circuits containing the selector input switches, so that no
current may flow through an input switch until the master switch
has been actuated. Since the actuating mechanism of the selecting
apparatus is set up to actuate the master switch after actuation of
the input switches (and, conversely, deactuate the master switch
before deactuation of the input switches), the input switch
circuits are always dead when the input switch contact points are
opening and closing, thus eliminating the arcing that is
characteristic in such switches in active circuits. This feature is
especially important when printed circuitry is used in the
selecting apparatus, because the contacts in printed circuits are
necessarily thin and deteriorate rapidly when subjected to any
appreciable amount of arcing.
Still another advantage of the present selecting apparatus is that
the construction of the selector input switch actuators provides an
automatic means for cleaning the input switch contact points
without requiring the disassembly of the apparatus. Each input
switch actuator comprises a longitudinal stem and a contact holder
slidably mounted at one end of the stem. The contact holder is
urged toward that end by a spring member that rides on a collar
fastened to the stem at the other end (the spring mounted contact
holder serving to permit the actuation of the input switch before
the actuation of the master switch). Bridging contacts in the form
of bow-shaped conductors are mounted on each contact holder, and
these contacts are positioned to engage stationary contacts in the
input switch circuitry when the stem is depressed.
By forming these contacts of a resilient conductor and by bending
this conductor downwardly on each end toward the stationary
contacts, the self-cleaning feature of the invention is achieved.
As the stem is gradually depressed, the outward ends of the
conductor first engage the stationary contacts, and then, as the
stem is further depressed, the conductor yields resiliently
upwardly. This movement forces the outward ends of the conductor to
slide outwardly on the stationary contacts, thus wiping dirt and
grease from the surfaces of these contacts, thereby insuring sound
electrical contact between the bridging contacts and stationary
contacts.
Accordingly, it is one of the objects of the present invention to
provide a selecting apparatus for vending machines and the like
that is compact, simple, and economical, yet provides a wide range
of individual selections.
It is another object of the invention to provide a selecting
apparatus that is well-suited for use in vending machines employing
logic circuitry selection systems.
It is a further object of the present invention to provide a
selecting apparatus for a logic circuitry selection system that
eliminates undesired vends through extraneous circuit signals or
through cheating.
It is still another object of the present invention to provide a
selecting apparatus wherein arcing between the contact points of
the selector input switches is eliminated.
It is yet another object of the present invention to provide a
selecting apparatus having a plurality of selector input switches
and also having a master switch that is actuated by the actuation
of any selector input switch after the input switch has been
actuated.
It is a further object of the present invention to provide a
selecting apparatus with self-cleaning contacts.
These and other objects, advantages and features of the present
invention will hereinafter appear, and for purposes of
illustration, but not of limitation, preferred embodiments of the
subject invention are described below and illustrated in the
appended drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a selector switch of the present
invention with the top removed and partially broken away.
FIG. 2 is a top plan view of a treadle bar of the present
invention.
FIG. 3 is a right-side view of the treadle bar shown in FIG. 2.
FIG. 4 is a top plan view of a master switch of the present
invention.
FIG. 5 is a side view of the master switch shown in FIG. 4.
FIG. 6 is a side view of a second embodiment of a master
switch.
FIG. 7 is a schematic perspective view, partially in section,
showing how each input actuator assembly interacts with the treadle
bar and thrust lever in order to actuate the master switch.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings, and more particularly to FIG. 1, a
selecting apparatus 12 constructed in accordance with the present
invention is shown therein. The selecting apparatus comprises a
switch box 14, which includes a base 16, a middle section 18, and a
top (not shown). The switching mechanism of the selector switch
includes a plurality of selector input switches 20 and individual
input actuators or plungers 22 (only one of which is shown in FIG.
1 for purposes of clarity), a master switch 24, and a master
actuator 26.
As shown in FIG. 1, the selector input switches 20 of the present
invention are of the single pole, single throw variety, with each
switch comprising a pair of electrically isolated conductors 28
having output terminals 30 and input terminals in the form of
stationary contacts 32. The input terminals of the switches are
mounted on a fixed surface, such as a circuit board 34, directly
beneath the respective input actuators and serve as the stationary
contacts of the switches. These switches may utilize copper
conductors and soldered contact points, or, preferably, printed
circuits may be imprinted on the circuit board 34. Printed
circuitry is preferred because it is inexpensive and requires less
space than conventional circuitry.
Although the present selecting apparatus could employ any one of a
variety of switching circuits, the preferred embodiment of the
present invention utilizes switching circuitry that finds
particular advantages in applications employing logic circuit
selection mechanisms. In a co-pending U.S. patent application of
Thomas P. Jachinek and Thomas A. Murrell entitled "Selecting
Apparatus and Method for Phonograph," U.S. Patent application, Ser.
No. 862,624, filed on Sept. 11, 1969 and assigned to the same
assignee as this application, such circuitry is described, and this
circuitry enables the present selecting apparatus to be used in a
coin-operated phonograph operation such that, wit twelve selector
input switches in the selector system, 1,000 separate selections
are possible, using ten of the twelve switches for input selections
and using the other two buttons as reset buttons. Although the
logic circuitry described in the above-mentioned co-pending
application does not form a part of the present invention, the
master switch feature and the compact arrangement of the present
selector switch and the ready adaptation of the switch to compact
printed circuitry arrangements makes the present selector switch
particularly advantageous in coin-operated phonographs and the like
employing such selection systems.
One of the input actuators or plungers 22 employed in the present
invention in order to actuate the individual selector input
switches is shown in detail in FIG. 7. Each plunger comprises a
flat metal stem 36, which is slidably mounted for longitudinal
motion within the switch box in a direction perpendicular to the
circuit board 34. The bottom end of the stem (FIG. 7 orientation)
protrudes through a hole in the circuit board and another hole in a
backing plate 38 of base 16 and rests on a spring 40 which is
maintained in direct alignment with the stem by means of sidewalls
42 within base 16. Spring 40 provides resilient support for the
stem 36 and maintains the plunger in a normally deactuated
position. The top of the stem protrudes out of the switch box
through a rectangular opening in the top thereof, thus presenting
an external plunger that may be depressed by an operator in order
to actuate an input signal. Within the switch box, a contact holder
44 is slidably mounted over the stem 36 and rests upon stops 53
located at the lower portion of the stem, such that bridging
contacts 46 mounted thereon will normally occupy a position just
above the input terminals of the input switches.
The contact holder is constructed from an electrically
non-conductive material, such as plastic, and comprises a
cylindrical upper portion 48 and a circular base 50, with the
diameter of the upper portion being relatively smaller than the
diameter of the base. Small protrusions 52 extend radially
outwardly from the base 50 on opposite sides thereof to hold the
contacts 46 in position.
Bridging contacts 46 comprise resilient, bow-shaped conductors,
which are mounted to the contact holder by means of protrusions 52
at a point in between the ends of the conductors. The outward ends
of each conductor are bent downwardly (FIG. 7 orientation) toward
the fixed surface and are positioned so that the ends extend below
the bottom of the contact holder. In the preferred embodiment of
the present invention, the legs of the bow-shaped conductors are
split into two segments in order to obtain proper resiliency and
optimize the electrical contact between the input terminals and the
contacts. It would, of course, be feasible to use a solid conductor
instead of the split conductors employed herein. Further, the
embodiment shown in FIGS. 1 and 7 employs two sets of bridging
contacts, one on each side of the contact holder. The double
contacts are used when the selector switch is employed in
connection with the logic circuitry described in the
above-mentioned co-pending patent application and are not necessary
when the selector system is performing a simple on-off
function.
The operation of the bridging contacts and the specific advantages
gained therefrom may be described briefly as follows. As the
plunger is gradually depressed downwardly, the outward ends of each
conductor first engage the stationary contacts of the input switch
and then the conductor begins to yield and bend upwardly. This
forces the contacts to slide outwardly on the stationary contacts,
and this action wipes dirt and grease from the contacts, thereby
insuring a good electrical contact between the contacts. After the
conductor yields a fixed distance, the bottom of the contact holder
engages the fixed surface and prevents further deformation of the
conductor.
Describing further the nature of the input actuator 22, a
compression spring 54 surrounds the stem and rests on the base 50
of the contact holder 44 and protrudes upwardly therefrom. At the
upper end of the spring is a collar 56, which is slidably mounted
on stem 36 through a rectangular opening therein, which is slightly
larger than the cross-sectional area of the stem. In the preferred
embodiment, this collar comprises a plastic cylinder having a
cylindrical opening 58 in the bottom thereof. The interior diameter
of the opening 58 is larger than the diameter of either the
compression spring 54 or the upper portion 48 at the contact
holder, so that the spring and the contact holder may slide into
the opening. The top of the collar has two flanges 62 extending
radially therefrom on opposite sides of the collar. The top also
has a non-circular recess 60 therein surrounding the stem that is
substantially large than the cross-sectional area of the stem.
A latching disc 64 fits on the stem through an opening 65 in the
disc. The outer perimeter of the disc is adapted to mate with and
fit snugly into the opening 60 in the collar. The disc performs a
latching function by means of the shape of the opening in the
center of the disc. This opening is non-circular in nature and has
a length in a first direction sufficiently long to permit the disc
to be slipped over the stem. The width of the opening in the disc,
however, is narrower than the width of the stem, so that the disc
may not be rotated about the wide part of the stem. The stem,
however, is provided with a notch therein opposite the top of the
collar, and this notch has a width slightly less than the narrow
measurement of the hole in the disc, such that the disc may be
rotated about the stem within the notch. In the preferred
embodiment the opening takes the form of two rectangular openings
that overlap at one corner of each opening. The opening in the disc
is aligned with respect to the outer perimeter of the disc such
that when the disc is slipped over the stem, moved down to the
notch in the stem, and turned 90.degree. in the notch, the disc is
in position to fit into the non-circular opening 60 in the collar.
With the disc fitting snugly into the collar, the disc can not
rotate or move either up or down with the stem, thus locking the
collar on the stem.
By structuring the input actuator so that the contact holder 44 is
slidably mounted on the stem and is urged downwardly against the
stops on the stem only by the force exerted by compression spring
54, two important advantages of the present invention are achieved.
As a stem is gradually depressed, the bridging contacts engage the
stationary contacts of the input switch and then yield upwardly to
perform the above-described wiping function. After the contacts
yield a fixed distance, however, the bottom of the contact holder
engages the circuit board and prevents the contacts from continuing
to bend upwards. If the plunger is depressed still further, no
additional pressure is applied to the contacts or to the circuit
board; rather, the stem merely continues to move through the
opening in the circuit board into the base, while the contact
holder slides up the stem, compressing spring 54. Thus, the plunger
may be depressed fully each time an input switch is actuated, and
there will never be any damaging impact between the input actuator
and the input circuitry, such as would result if the actuator were
permitted to "bottom out" on the circuit board. This feature,
therefore, prolongs the life of the input switch and the actuator
and protects the switch assembly from damage that might otherwise
result from a vigorous actuation of the selector switch.
Another advantage of the present input actuator is that the
actuator may be employed to perform a sequential switching function
of two separate switches (i.e., the selector input switches and the
master switch) and thereby eliminate arcing between the contact
points of the input switches. In the operation of the present
invention, the depression of a plunger first actuates its
respective selector input switch, and then, on further depression
of the plunger, the contact holder slides up the stem and the
plunger proceeds to actuate the master switch. Likewise, when the
plunger is released, the master switch is first deactuated and then
the selector input switch is deactuated. Thus, the master switch is
always open when the contact points of the selector input switch
are opening and closing. When, as in the preferred embodiment, the
master switch controls the energization of the input switch
circuits, the input switch circuits will always be dead when the
contact points are opening and closing, because the master switch
is always open at those times. Since contact arcing is a phenomenon
that occurs only when points are opening or closing in an active
circuit, this feature eliminates arcing between the contact points
and thereby prolongs contact life. When the preferred printed
circuitry is employed in the input switches, this advantage is
especially important, because printed contact points are quite
light and have a short life when subjected to an appreciable amount
of arcing.
A first embodiment of a master switch employed in the present
invention is shown in FIGS. 4 and 5. This switch comprises a
plurality of metallic blades 66 separated by separators 68 formed
of a non-conductive material, such as bakelite. In the preferred
embodiment of the subject invention, bakelite separators
one-sixteenth of an inch thick are employed.
The uppermost blade of the master switch (FIG. 5 orientation)
comprises a spring member 70. This spring may be constructed of any
resilient, conductive material, but in the preferred embodiment of
the present invention a tempered bronze blade 0.020 inches in
thickness is employed. The lowermost blade in the master switch
(FIG. 5 orientation) is a stationary blade 72. In the preferred
embodiment, this blade is formed of a tempered bronze spring 0.020
inches in thickness and is provided with a silver palladium contact
point 74 at the left end thereof. The longer of the two remaining
blades is a shifter blade 76. This blade is connected by a barrel
spring 78 (alternatively, a U-shaped roll-over spring may be
employed) to a moving blade 80, which is also provided with a
silver palladium contact point 81 positioned opposite contact point
74 in the stationary blade. The shifter blade is also provided with
an opening therein, such that the moving blade may pass through the
shifter blade without coming in contact therewith. The master
switch is also provided with two output terminals 84, one of which
is attached to the stationary blade 72 and the other of which is
attached to the moving blade 80.
The operation of the master switch may be described as follows. In
the position shown in FIG. 5, the contact points are separated, so
that the master switch represents an open circuit. The switch may
be closed by moving the shifter blade in an upward direction (FIG.
5 orientation). This causes the barrel spring to compress and bends
the moving blade 80 and the spring member 70 in an upward
direction. When the shifter blade moves upward further and
approaches alignment with the moving blade, the spring member 70
and the inherent resiliency in the moving blade eventually overcome
the upward force exerted by the barrel spring and force the moving
blade to snap downward through the opening in the shifter blade.
After the moving blade has passed downwardly through the shifter
blade, the direction of force of the barrel spring is reversed, and
the barrel spring forces the moving blade downward, thereby causing
the contact points 74 and 81 to snap together quickly, with a
minimum of arcing between the contact points. To disengage the
switch, the opposite procedure is followed.
An alternative master switch 24', equally effective in the present
invention, is shown in FIG. 6. This master switch also includes
four blades 66' which are separated by non-conductive separators
68'. The upper blade again is a spring member 70', but the
positions of the other three blades has been altered somewhat. The
shifter blade 76' in the second embodiment is the lowest blade in
the stack (FIG. 6 orientation), and the two middle blades are
provided with electrical contacts. By putting the two electrically
conducting blades in the center, the need for an opening in the
shifter blade is eliminated. The uppermost of the middle blades is
a moving blade 80' and is provided with a silver palladium contact
81' of the type used in the first embodiment. The lower contact
blade 72' of the two middle blades is also provided with a silver
palladium contact 74', which is positioned opposite the contact
point on the moving plate. The output terminals in this second
embodiment are attached to each of the two middle blades of the
master switch. The spring force provided for snapping the contact
points together when the switch is actuated is supplied by a
compression spring 86, which is attached at one end to the moving
blade 80' and at the other end to a non-conductive spacer 88. One
end of the spacer is attached to the shifter blade 76', and the
other end of the spacer is attached to the spring member 70', with
the compression spring 86 being attached to the spacer at a point
between the two ends. The outer end of the lower contact blade 72'
also is attached to the spacer, at a point adjacent the shifter
blade.
The operation of this second embodiment of the master switch is
similar to the operation of the first embodiment of the switch but
provides one principal advantage over the first embodiment, namely,
the contact points do not have to pass through the shifter blade in
order to effect engagement between the moving and stationary
blades. In the second embodiment, when the shifter blade is in its
deactuated position, the compression spring forces the moving blade
in an upward direction, away from the lower contact blade 72'. When
the shifter blade is actuated and moved in an upward direction, the
spring at first forces the moving blade upward, but when the end of
the compression spring attached to the spacer moves past the end
attached to the moving blade, the compression spring forces the
moving blade to snap downward and effect engagement between the
contact points of the moving blade and the lower contact blade. As
before, when the shifter blade is moved back to its original
position, the contact points are again separated and the master
switch again becomes an open circuit.
The master actuator 26 comprises apparatus in the switch box that
is designed to actuate the master switch in response to the
actuation of any one of a plurality of input switches. The master
actuator 26 comprises a thrust lever 90 slidably mounted for
longitudinal motion within the switch box. The thrust lever 90 has
an outward end 92 that is adapted to move through an opening 94 in
the side of the switch box when the thrust lever is actuated. The
master switch 24 is mounted on the outside of the middle section of
the switch box in such a position that the end of the shifter blade
covers the opening 94 in the switch box (as shown in FIG. 1). Thus,
when the thrust lever is actuated and slides through the opening
out of the switch box, the end of the thrust lever 92 engages the
shifter blade and thereby effects the actuation of the master
switch.
The thrust lever is actuated in response to the actuation (i.e.,
depression) of any one of the individual selector input switch
actuators by means of cam means in the form of treadle bars 96,
each of which are rotatably mounted in U-shaped supports 98 on the
inside of the middle section 18 of the switch box. Each treadle
bar, as shown in FIGS. 2 and 3, comprises a pivotable transverse
rod 99 having a series of input cams 100 extending horizontally
therefrom (FIG. 7 orientation) into engagement with the flanges
extending from the collars on the input actuators. A thrust cam 102
protrudes downwardly from the treadle bar into an opening 104 in
the thrust lever 90.
The interaction between the input actuators and the thrust lever
may be described briefly as follows. When any one of the input
actuators is depressed, such as the one shown in FIG. 1, the
flanges resting on cams 100 displace the cams and cause the treadle
bar 96 to rotate. This causes the thrust cam on the bottom of the
treadle bar to move within the opening in the thrust lever and
engage a cam surface 106 on the end of the opening. This in turn
forces the thrust lever to slide out through the opening in the
side of the switch box and actuate the master switch 24. Thus, when
any one of the input actuators is depressed (the preferred
embodiment provides positions for 12 such input actuators) both the
master switch and the input switch associated with that particular
input actuator are actuated.
As stated previously, one of the advantages of the master switch
feature is that arcing between the contact points of the selector
input switches may be eliminated by placing the master switch in
the circuit controlling the energization of the selector input
switches and by constructing the actuation mechanism so that the
general depression of each plunger sequentially actuates first its
respective selector input switch and then the master switch. This
sequential operation may be effected by positioning the stationary
contacts at a position such that they will engage the bridging
contacts upon partial depression of the plunger and by designing
the master switch actuator assembly to actuate the master switch
only when the plunger is depressed past the point where the
bridging contacts engage the stationary contacts.
Another advantage achieved by the master switch feature of the
present invention is that signals arising from some source other
than the actuation of a selector input switch i.e., either
extraneously or through an attempt to cheat the machine) may be
eliminated from the circuit. When the selecting apparatus of the
present invention is used in a vending machine having a logic
circuitry selection mechanism (where extraneous signals often
duplicate the signals generated by the selecting apparatus), such
extraneous signals are eliminated by establishing separate circuits
for the input switches and the master switch and by connecting
these circuits to the selection sensing mechanism through the two
inputs of an AND gate. Thus, when a selection is made, separate
signals are generated in an input switch circuit and the master
switch circuit simultaneously, and these signals appear at the
inputs to the AND gate at the same time, thereby causing the AND
gate to transmit a signal to the selection sensing mechanism. But,
when an extraneous signal or a signal generated by cheating arises
in either circuit, the signal will not be transmitted to the
selection sensing mechanism by the AND gate, because of the absence
of a corresponding signal at the outer input to the AND gate.
Because it is extremely unlikely that two separate extraneous
signals would appear in both circuits at the same time and because
it would be difficult to impossible to generate such signals by
cheating, the master switch utilized in this manner virtually
eliminates the problem of undesired vends that would otherwise be
present in a machine employing a logic circuitry selection
mechanism.
It should be understood that the embodiments described herein are
merely exemplary of the preferred practices of the present
invention and that various changes, modifications, and variations
may be made in the arrangements, operations, and details of
construction of the elements disclosed herein without departing
from the spirit and scope of the present invention, as described in
the appended claims.
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