Note: Descriptions are shown in the official language in which they were submitted.
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~0 FI,UORESCENT BALLAST AS5EMBLY
BACKGROUND OF T~E INVENTION
1. Field of the Invention
This invention relates to ballast assemblies
and more specifically to a novel and improved ballast
assembly includin~ a bobbin specially suited to automated
construc~ion methods.
2. Descri~tion of the Prior Art
A fluorescent lamp customarily requires a ballast
for providing the necessry starting voltage. A ballast
typically includes at least one transformer coil wound on a
coil bobbin and certain associated circuitry which is
known. The bobbin may be provided with metallic pins for
interconnecting magnet wire ends coming from the coil to a
printed circuit board assembly. Thus, the complete ballast
assembly may include a printed circuit board assembLy, as
well.
Different lamps having different power require-
ments and starting voltages require different ballasts,
One ballast may vary from another in the particular circuit
components used, the size and shape of the transformer
coil, or the locations of starts, taps and finishes on
similarly sized transformer coils.
; Until this invention, such ballasts were manu-
factured and assembled using methods which are highly
manual labor intensive, with resulting labor costs per unit
accounting for nearly hal the total production cost per
unit. Bobbin and transformer coil arrangements designed
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for and raquiring further assembly to printed clrcuit assemblies
are ~hown in A.G. Weyrich, U.S. Patent No. 3,076,165, where
terminal lugs are provided to be plugged lnto corresponding slots
in a printed circult board; and in ~.A. Peterson, U.S. Patent No.
4,347,4gO, where pins are similarly provlded for electrical
interconnections to associated electronic: circuitry on a printed
circuit board. Since a ballast may include the printed circuit
board as well, a standardized method of assembling not only the
coil and bobbin, but also the lnterconnectlon pins, printed
circuit board and associated electronic circuitry, would
substantially reduce the overall cost of producing ballasts.
SummarY
:According to ~he present invention there is provided a
method of assembling a ballast adapted ko be used in a fluorescent
lamp, comprising the steps: providing a bobbln for wlnding a coil
of wire, the hobbin having a bobbin core and a planar flange at
each end of the bobbln core, at least one of the flanges having a
: plurality of holes ex~ending from an edge of the flange into the
flange in a direction substantially parallel to the plane of the
~0 flange, the bobbin further comprising at least one lntegral post
connected to and extending away from the edge of the flange in a
direction substantially paral1ei to the plane of the flange;
automatically insertlng a connecting pin into one of the holes of
the ~lange edge; automatically winding a coil of wire onto the
bobbin core, an end o~ the coil wire forming a lead wire;
automatically winding the lead wire around the connecting pln;
automatically solderlng the lead wire to the connecting pin;
providing a printed circuit board having a pattern oi through
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holes, the pattern corresponding to the locations of the post and
the holes of the flange edge; positioning the printed circuit
board so that the pattern of through holes is aligned with the
corresponding post and holes of the flange edge; and placing the
printed circult board s~rai~ht onto the bobbin flange edge, the
post and the connecting pin being inserted into and passing
through the corresponding through holes of the pattern.
Accordlng to another aspect oE the present inven~ion
there is provided a ~luorescent lamp ballast comprising: a ~irst
bobbin, the bobbin having a central longitudinal opening extending
from a substan~ially planar flange at one end of the bobbin to a
second substantially planar flange at the other end of the bobbin;
a second bobbin, the second bobbin also having a central
longitudinal opening extending from a substantially planar flange
: at one end of the second bobbin to a second substantially planar
flange at the other end of the second bobbin, with one flange of
each of the first and second bobbins disposed ad3acent the other
so that the central longitudinal openings of the ~irst and second
bobblnæ are substantially aligned; a magnetic core having at least
a first portion inside the aligned bobbin central openings, and
second and third portions disposed on opposite sides oE the
bobbins; each bobbin Elange having a plurality of holes extending
inwardly Erom an outer flange edge on a side of the respective
bobbin withouk the second or third magne~ic core portions disposed
thereon a primary coil ~ound on one o~ the bohbins, and a lag coil
wound on the other bobbin, the coils having starts, taps and
finishes; conductive pins partially inserted into a number of the
flange edge holes, each of the pins being electrically coupled to
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one of the coll starts, taps and finishes; and a planar elongated
printed cixcuit board whose length and width dimensions are
approximately the same as that of the first and second bob~ins
positioned end-to-end, the circuit board having a predetermined
pattern of holes therethrough, the holes being electrically
coupled in a predetermined pattern by conductlve strips on the
printed circuit board, the printed circult board being
substantially perpendicular to and in contact with each of the
conductive pin-bearing flange edges, each of the conductive pins
extending through one of the holes throu~h the printed circuit
board and also being electrically coupled to the printed circuit
board conductive strip adjacent the hole through which each
respective conductive pin passes.
BRIEF DESCRIPTION OF THE DRAWINGS
The following is a description by way of example, of a
preferred embodiment of the present lnvention, reference being had
to the accompanying drawings, in which:-
Fig. 1 is an exploded perspective view of a ballast
according to ~he present invention;
Fig. 2 is a perspective view of the fluorescent ballast
of Fig. 1, after assembly; and
Fi~. 3 is a diagrammatic repre~entation of aspects of
automated ballast assembly accordlng to the present invention.
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1 DESCRIPTION OF THE PREFERRED EMBODIMENTS
. .
Fig. 1 shows an exploded view of the inventive
ballast, and FigO 2 is a perspective view of the assembled
device. Ballast 11 comprises a laminated core 12. The
S core 12 includes a center bar lamination stack 14 and a
figure-eight-shaped lamination stack 15. The laminations
may be held together by clips 17. The center bar 14
e~tends from inside one end 18 of the figure~eight-shaped
opening to the other end 19 of the opening, forming four
spaces or windows 22 in the two openings of the figure-
eight shape. Bobbins 30,40 are located around center bar
14. Coils of wire (windings) 31,41 are wound around
bobbins 30,40, respectively, and may comprise the primary
and lag windings of the ballast.
The bobbins 30,40 may be made of any well known
relatively hard plastic. Since bobbins 30,40 have similar
inventive features, only one bobbin 30 will be further des-
cribed in detail. Bobbin 30 has a central, generally
rectangular bobbin core 33 for holding the winding 31.
Through the bobbin core 33 passes a central rectangular
hole 34 for receiving the center bar 14. Substantially
planar flanges 35,36 are providea at the ends of the bobbin
30 for purposes to be described.
It is customary to provide flanges 35,36 to
retain winding 31 on the bobbin core 33. The inventive
flanges 35,36 according to the present invention have
built-up portions 39,40 on at least one side of the bobbin
30. Extending outwardly from the edges of the built-up
portions 39,40, substantially parallel to one another and
to the respective planes of each of the flanges, are
integral posts 42, spaced at predetermined locations. The
built-up portions 39,40 further have a plurality of holes
44, which mày be rectangular, for receivinq connecting pins
45, which also may be rectangular in cross-section. The
3S holes 44 extend from the edge of each flange into that
flange in a direction substantially parallel to the plane
of the flange. The holes 44 are spaced at predetermined
locations, for reasons made clear below.
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1 Ballast 11 further comprises a printed circuit
board 24, which may have electrical components connected to
it, as is customary. Printed circuit board 24 has a
pattern 25 of through holes 26 corresponding to the loca~
tions of the posts 42 and holes 44 of the bobbin flanges
35,36. The pattern 25 is formed at several locations and
orientations on the circuit board 24, thus permitting
circuit board 24 to be affixed to the the bobbins 30,40 in
several different positions, in accordance with aspects of
the invention.
In any particular ballast according to the
invention, fewer connecting pins 45 may be required than
the number of holes 44 provided for these pins. Pins 45
and posts 42 provide structures onto which winding leads
from coil starts, taps and finishes can be wound and
attached. Different ballast variations may have starts,
taps and finishes located differently, yet the connecting
pins 45 and posts 42 are still located in
predetermined spacing relationships.
According to the invention, the bobbin and
printed circuit board thus provide an extremely flexible
~- and versatile combination which can be used to make many
different ballasts. Certain ballasts may require all
available connecting pin holes 44 to be used; others may
require only a few pins 45 to be automatically inserted
into the bobbin flange. Also, a particular printed circuit
board 24 may not occupy all of the available posts 42, thus
permitting another printed circuit board to be mounted on
the remaining posts.
Furthermore, certain fluorescent lamps may
require two or more o each of the primary and lag coils,
or one ballast assembly cluster may be used for a number of
lamps. In these cases, ballast coils may be arranged
end~to-end or side-by-side, with uniform printed circuit
boards having predetermined repetitive uniform hole patterns
overlapping from bobbin to bobbin. This modular approach
provides for greater versatility than was possible before
this invention.
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1 Other features of ballast 11 include magnetic
gapping ~insulating) material 50, which, if used in a
particular ballast, may be positioned between the windings
31,41 and the figure eight-shaped lamination 15. The coils
and core may be mounted in a housing 52, having grommets 53
through which wires 54 may pass for providing power in,
power out, ground, and switch connections.
The above-described structure provides a highly
versatile ballast construction which may be used to produce
a number of different ballasts from the same combination
of basic standardized piece parts. For example, the wind-
ings 31,41 may have more or fewer turns; the core 12 may
have more or fewer lamination layers; different arrange-
ments of electrical components may be required; or connect-
ing pins 45 may be located in any available holes 44. Asnoted above, more than one circuit board 24 may be mounted
on the posts 42 of the flanges 35,36 where additional
circuitry or coil interconnection points are required.
Many other variations, modifications and substitutions
will be readily apparent to those skilled in the art, and
are not considered by the inventors to deviate from the
spirit or scope of this invention.
Referring to Fig. 3, an automated assembly pro-
cess is shown which takes advantage of the structural
features of the ballast according to the present invention.
While each assembly stage is conventional, the collection
of these stages in a continuous automatic process has not
before been realized. Only with highly modular and versa-
; tile piece parts, such as those descxribed above, can an
automated assembly process provide the large number ofballast variations possible.
Bobbins stored in a hopper 60 are fed by a
vibratory bowl feeder 62, or similar feeding device, to a
loading device 64 which automatically places individual
bobbins onto a moving caro~sel 70. When a bobbin according
to the invention is placed on the carousel 70, the precise
locations of the posts and holes are accurately determin-
able with respect to the carousel.
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Proceeding around the moving carousel, a bobbin
30 passes a detector 72 for initiating a timed sequence of
events to be described. Since the travel speed of the
carousel is easily determined, the precise position of a
bobbin 30 at any given instant is determined. As a bobbin
30 proceeds around the carousel 70, one or more conductive
connecting pins 45 may be automatically inserted or press-
fit at stage 74 into one or more predetermined receiving
holes 44 on the bobbin flanges. Proceeding further, the
bobbin may be tested at stage 76 or probed for the presence
of the proper number of connecting pillS 45 . As previously
described t the pins and posts of the bobbin are oriented
generally parallel to one another, thus permitting straight-
in insertion of the printed circuit board, as will be made
more clear.
A predetermined amount of wire is automatically
wound onto the bobbin by, for example, a twelve spindle
winder 80. Wire leads from starts, taps and finishes of
the windinq are automatically dressed at stage ~2 onto one
or more of the posts 42 and connecting pins 45 . Since
each of the posts 42 and connecting pins 45 necessarily
protrudes beyond the edges of the bobbin 30, the leads may
be affixed in place by flow soldering techniques, including
dipping first in a flu~ composition at stage 84, and
then in a molten solder bath at stage 86.
Electrical resistance of the bobbin so assembled
may be tested automatically at stage 88 further along the
carousel. The prepared bobbin may then be automatically
taped at stage 90 with gapping material 50, if desired, and
placed in a storage and transfer tray 92.
Each of the aforementioned automated steps is
made possible, in part, because the locations of the
connecting pins, bobbin core, flanges, etc. are precisely
determined once the bobbin is placed on the carousel. The
entire winding assembly process can be computer controlled,
so that bobbins of different sizes, such as the primary and
lag bobbins described above, can be assembled on the same
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1 carousel, as well as different pin and winding configura-
tions of the same bobbin. The method of winding assembly
eliminates previously required assembly steps known by
those skilled in the art as stick-winding, paper wrapping,
sawing (of the wound stick), sizing, gauging, twisting (of
leads), hand soldering, and picking. This reduces the cost
of manufacture of ballast assemblies by eliminating many
manual labor intensive steps, while at the same time
improving consistency and quality of the finished ballast.
After the automatic winding processes, the center
bar 14 of the laminated core 12 may be inserted through the
bobbin core 34. The remaining portions 15 of the laminated
core are specially designed to be easily and rapidly pressed
into position surrounding the bobbin.
With the ballast core laminations 15 in place,
simplified final assembly according to the present inven-
tion may be done. The printed circuit board 24 having
predetermined through holes may be inserted straight onto
the pins 45 and posts 42 extending from the bobbin flanges
39. This eliminates the costly and time consuming steps of
locating the coil leads or attached terminals or connecting
pins to appropriate connection points on the circuit board.
By simply placing the circuit board onto the posts of the
bobbin flange, the connecting pins are already properly
aligned with the circuit board. Electrical co~ponents may
be placed on the circuit board and all connections may be
completed at one time by wave soldering. Connecting pins
may even be bent over against the circuit board before wave
soldering, to better hold the circuit board to the bobbin/
core assembly. The entire assembly may then be placed
in its housing and potted, as i5 customary.
While the invention has been disclosed with
reference to preferred embodiments, it will be readily
understood by those skilled in the art that various changes
in form and details may be made without departing from the
spirit and scope of the invention.
