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Патент USA US3091730

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May 28, 1963
E. J. HUBERTY
3,091,720
BALLAST APPARATUS WITH DIMMING CONTROL
Filed July 3, 1961
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May 28, 1963
E. J. HUBERTY
3,091,720
BALLAST APPARATUS wrm DIMMING CONTROL
Filed July 3. 1961
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May 28, 1963
3,091,720
E. Jl HUBERTY
BALLAST APPARATUS WITH DIMMING CONTROL
Filed July s. 1961
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United States Patent Omce
1
3,091,720
Patented May 28, 1963
2
tributes without being expensive and complicated to build
3,091,720
BALLAST APPARATUS WITH DIMMING
CONTROL
Elmer J. Huberty, Chicago, lll., assigner to Advance
ill'rrans?former
Co., Chicago, Ill., a corporation of
mois
Filed July 3, 1961, Ser. No. 121,414
22 Claims. (Cl. 315---98)
and install.
Prior 籺o this invention, dimming ballasts for lluorescent
lighting did not meet the requirements set forth above.
Even the most basic of requirements were ditlicult, if
not impossible to achieve.
This invention has as its principal object, the achieve
ment, not only of the basic requirements of dimimiug bal~
lasts set forth above, but, as well, of all of the ideal re
This invention relates generally to devices which are 10 quirements set forth above. This is accomplished on the
farmharly known 籥s ?ballasts? and more particularly is
concerned with the construction of a ballast which is
basis of certain structures which will be described.
`In achieving a structure which will enable full dim
intended for use with gaseous discharge lamps for light
ming control of fluorescent lamps over a wide range of
mg purposes ?and which has a novel dimming control
brilliance with reliability in starting and maintaining op
structure.
15 eration, the invention uses an improvement over prior
The gaseous discharge device inherently is a constant
structures which may `be termed a peaking circuit to su
potential device which requires a certain voltage to ionize
perimpose a high voltage peak upon each half-cycle of
the gases therein `and a certain other voltage, substan~
the voltage which normally would be applied to the gase
tially lesser in value, to maintain .the same ionized. At
ous discharge device. Since the effect upon the R.M.S.
lower than the required ignition voltages the device will 20 voltage applied to |the liuorescent lamp is not changed
not ignite, and at lower than the required operating volt
effectively by this high peak, the `brilliance of the lamp
ages the device normally will ybecome extinguished.
likewise is not affected, although 4ignition at all values of
The problems which are involved in the construction
R.M.S. is ensured for each half-cycle. It should be re
of Vapparatus with which this invention is concerned are
melmbered that the actual gaseous discharge within a
several in nature. Some of these are characteristic of 25 fluorescent lamp is extinguished between half cycles, the
all `apparatus for igniting and operating gaseous discharge
retention of illumination apparent to the human eye be~
devices, and certain other problems are related only to
ing caused by the 駏orescing of the phosphors coating the
the particular functions desired of ballasts which include
inside of the fluorescent tubes.
dimming control means.
The ordinary dimming circuit uses an autotransformer
The basic requirements of most gaseous discharge bal 30 connected with a variable output transformer, the varia
lasts are to provide the necessary igniting and operating
ble output transformer being interposed between the pri
voltages from a source of A.C. voltage of relatively lower
mary and second-ary of the autotransformer to supply a
value than either the igniting or operating voltage, to
variable voltage in series with the secondary winding.
ballast 籺he device after its gas has ionized, that is, the
The R.M.S. and peak voltages applied to the lamp vary
lamp has ignited to prevent excessive 駉w of current 35 directly with the variation in the voltage tapped olf the
from causing the latmp to destroy itself, and to do these
variable transformer. By peak voltage here it is 韓
e駃ciently and economically and without the need for
tended to describe a peaking of a sont that is often found
complex and involved structures and circuits. Addi
in the wave form of high leakage reactance transformers
tional requirements may be posed by virtue of the re
of the type desirable for the lluorescent lamps ordinarily
quirements of certain circuits, 籺he use of certain kinds (0 used in dimming circuits. Since the peak voltage de
of gaseous discharge devices and the like. For example,
certain vapparatus may 籦e required to operate at high
power factor, certain kinds of lamps require filament
windings in the transformers serving same and continuous
flow of current in the filaments, and the like.
The value of lighting with vari-able intensity is not the
concern of this invention, but, that there are important
advantages to the control of the amount of light achieved
from a given source will be denied by noue.
The fac-t
termines whether the lamp will re-ignite between half
cycle extinguishment obviously the minimum value of
peak voltage limits the range of usefulness of a given
device.
It has ?been found that the condition of pearl:
voltage at which the lamp no longer will reliably re-ignite
in known `ballasts is one in which the R.M.S. of the lamp
voltage, and hence its brilliance, is quite high.
A
The invention, therefore, provides a structure in which
the peak voltage of the voltage wave applied to the lamp
remain-s Vthat the specifications of a great many lighting 50 is substantially independent of changes in the R.M.S.
installations, both residential and commercial, require
voltage, or at least decreases at a rate substantially less
manual (and sometimes automatic) control of the in
than the rate at which the R.M.S. voltage decreases, so
tensity of illumination. This invention is concerned with
that the lamp may be dimmed to a condition of extremely
the construction of ballast apparatus which provides this
low brilliance before its re-igniting characteristics are
control for rfhlorescen-t lamps.
affected adversely. This property is directly concerned
The additional requirement >for Ithe 籨imming control,
.also with the ability of the lamp to be ignited at low
as this form of variation is known, for gaseous discharge
intensities of brilliance, after once having been fully
lamps is primarily to be able to achieve the full range
extinguished.
of variation of lighting intensity without cancelling the
The invention contemplates, among other things, a
ordinary functions built into a given ballast. Ideally, 60 novel magnetic structure for a peaking transformer which
a dimming ballast should be able to start land operate
will accomplish the desired functions outlined above, and
at any condition of light output so that the user may
additionally circuit details which will complement the
turn ot� the apparatus while it is at low intensity with
magnetic structure. Two of these details should be con
out -being required to re-set the dimming control, know
sidered most important and fundamental to the inven
ing that when next he energizes the apparatus it will start 65 tion, and they are means tor causing the pulse produced
reliably; a dimming ballast should be able to operate
by the peaking circuit to be superimposed upon a ringing
at lthe lowest intensity without tiickering either contin
signal of frequency substantially higher than the line fre
ually or intermittently; a. dimming ballast should be able
quency; and means for suppressing the R.M.S. voltage
increase which would be produced in the peaking cir
to operate a-t all intensities without an unusual increase
cuit with increased differential between the lamp R.M.S.
in temperature, without radical changes in the power fac
voltage and the peak voltage. The first mentioned phe
tor; anda dimming ballast should have all of these at
3,091,720
3
nomenon has been `found to give substantial improvement
in the reliability of ignition of the fluorescent lamps at
which has been eliminated by the invention is that where
a group of lamps is used together the lower limit of
by a magnetic shunt. These two windings are connected
in autotransformer relationship across a fluorescent lamp.
The preferred lamp is the rapid start lamp which has a
heated filament that carries current continuously because
`such lamps will remain ignited for very substantial re
ductions in operating voltage and are more easily re
dimming is the light intensity at which the first lamp
fails to reignite. The peak voltage required to re-ignite
ignited than instant start lamps, for example.
To achieve the dimming control, instead of providing
conditions of low lighting intensity.
One of the important disadvantages of prior structures
a lluorescent lamp varies from lamp to lamp. Since the
a direct connection between the primary and secondary,
intensity of the lamps is still rather high compared to the 10 the prior apparatus included a variable transformer con
condition of no light at all, in ordinary dimming circuits
nected across the line in parallel with the primary and
the extinguishment of one of several lamps usually re
having a movable brush wiping taps or exposed points
sults in a substantial sudden decrease in illumination
which is annoying :and undesirable. The invention enables
the light intensity of a plurality of lamps to be decreased
almost to complete extinguishment without the extinguish
ment of any one of them.
The use of complicated and expensive circuitry per
haps may provide some solution to the problems men
tioned, but it is believed that even through the use of
such apparatus, the important objects of `the invention
have not been achieve-d in prior structures. It is there
fore even more of an advance in the arts and sciences to
so that the total voltage of the variable transformer or
portions thereof may be used to aid the secondary volt
age to increase the total voltage available across the
lamp, the lamp being unable to sustain itself with the
voltage of the secondary alone. The terminal of the sec
ondary winding opposite that connected to the lamp was
connected to the brush of the variable transformer. This
general structure is also characteristic of the invention
herein also, but there are additional components which
provide the substantial improvement.
As stated above, the improvement generally comprises
the addition of a peaking circuit to provide a continuous
achieve the salutary and desirable results of the inven
tion with apparatus which is economical and simple. 25 peak of voltage superimposed upon the voltage applied
to the lamp so that the re-ignition of the lamp is ensured
One result which has only been alluded to above, for
for substantially all conditions of brilliance. Various
example, is the elimination of flickering which has been
means for providing peaking in gaseous discharge circuits
found to occur in many prior ballast circuits at low
are known, but in this invention the structure provided is
intensity illumination. The structure herein has corn
pletely eliminated all ilickering at all useful intensities 30 not obvious for several reasons. Merely providing peak
while rendering the ignition of the lamps substantially
ing will result in a constant peak superimposed upon the
more dependable.
R.M.S. voltage and will provide additional R.M.S. volt
age. Thus, undesirable instant starting of the rapid start
A preferred embodiment of the invention has been
lamps at low intensities will occur which shortens the
range of intensities, using a so-called rapid start 駏ores 35 life of the lamps by gradually destroying their filaments.
constructed and successfully operated over an extended
cent lamp. The rapid start `lamp is one in which the lamp
Additionally, the added R.M.S. voltage permits the in
is provided with filaments that are heated at all times,
which therefore provides a reliable and continuous source
tensity of the lamp to be decreased materially, without
materially decreasing the peak voltage, thus obviating the
of electrons for aiding ignition and reignition of the
bene駎s of peaking.
lamp. The starting and operating voltages of these fluo 40
In the invention herein, the peaking occurs without any
increase in R.M.S. voltage; the peak on the voltage wave
rescent lamps are substantially lower than 駏orescent
is substantially constant regardless of the amplitude of
lamps such as the so-called instant start lamps. The
the R.M.S. voltage; and it occurs with a ringing voltage
specification an?d drawings describe the apparatus in con
wave that improves its reliability.
siderable detail, but only by way of example and not
In FIG. 1 there is illustrated a circuit using the inven
limitation. For example, the structure readily may be 45
tion for the ignition, operation and control of intensity
adapted to igniting and operating two or more lamps,
of a single rapid start lamp L having filaments 10 and 12
and these lamps need not be of the rapid start structure,
in the ends thereof. The fluorescent lamp ballast 14 is
but preferably should be.
In the drawings:
shown enclosed in a broken line block since these are
PIG. l is a `circuit diagram of a ballast circuit using 50 components normally included in a single housing, such
the construction of the invention herein, shown applied
to the ignition and operation of a single gaseous discharge
lamp which has filaments in its envelope.
FIG. 2 is a semi-diagrammatic view of the .so-called
peaking transformer, the same being a top plan view of 55
mally being a separate component, commercially avail
the same with portions in section to show the contours
of the magnetic core thereof.
FIG. 3 is a view similar `to that of FIG. 2 but of the
in a broken line block since it can be separately manu
factured also. The two blocks l14 and 18 are connected
by the dotted lines 2t]` to indicate that the ballast 14 and
as a metal canister.
The variable transformer 16 is
shown enclosed in another broken line block, this nor
able in many different designs. The peaking means of
the invention is designated 18 and is also shown enclosed
the peaking circuit 18 conveniently may be included with
ballasting transformer.
FIGS. 4a, 4b, 5a, 5b, 6a, 6b, 7a, 7b, 8a and 8b are 60 in a single canister and potted together. Under such
graphs of the voltage across the terminals T-2 and T-6
circumstances, there will be six leads emerging from the
canister. In the circuit there are shown the four lamp
under open circuit condition, with the brush of the varia
leads 22, 24, 26 and 28 ; the two primary leads 30 and 32;
ble transformer in different locations, for the condition
and the two peaking circuit leads 34 and 36. The leads
(a) of the ringin?g condenser not in circuit, and (b) the
ringing condenser in `the circuit.
65 24 and 30 are common, and this is also true of the leads
32 and 36.
FIGS. 9a and 9b are graphs of voltage across the sec
If the three components 14, 16 and 18 are made in
ondary winding S-S with and without the condenser C-2
dependently and are required to be connected up with
in circuit.
the lamp L and the A.C. line by the installer, the ballast
The basi-c invention comprises an improvement upon
known ballasting apparatus with dimming control for 70 14 will have the four lamp leads 22, 24, 26 and 28 emerg
ing therefrom, along with the lead 32 and a sixth lead
operating fluorescent lamps, and especially such appa
38 which is to connect with the peaking circuit 18. The
ratus for use in operating fluorescent lamps at high power
peaking circuit will have two leads 34 and 36 and a third
factor. The known apparatus for operating a single lamp
lead which is to be connected to the lead 38 from the
comprises a high leakage reactance transformer provided
ballast 14. The variable transformer 16 will have only
with a primary winding and secondary winding, separated
3,091,720
three leads extending Vtherefrom although from FIG. l it
across the lamp L is the vectorial sum of the voltages of
appears as though there are six. The conductors 4G and
42 are merely extensions of the leads 30 and 32 respec
P-1 and S-2, if we assume that the brush lead 34 is con
nected directly to the lead 38 as in prior structures.
Since the arrows V-S and V-P are in the same di
tively, drawn only to render the diagram easier to follow,
while the conductor 36 is actually connected to the lead
3-2 exterior of the housing of the variable transformer 16.
The lead 34 connects with the wiper or brush 44 of the
transformer.
Consider now the ballast circuit and the variable trans
former circuit. The ballast circuit includes a transformer
46 ywhich is shown in physical embodiment in FIG. 3
mounting a primary winding P-l connected across the
line at terminals 48 and 50 through the leads 30 and 32
and extensions 40 and 42 respectively. In the practical
example the terminal 48 was at ground potential and the 15
lead 40 was white, while the terminal 50 was the ?hot?
side and the lead 4t2 was black. This is a matter of choice
in this case, however, since the connections could be re
versed. The starting aid to be provided by a metallic
fixture mounting the lamp L, if desired, would have to
take the polarity of the terminals 48 and 50 into con
sideration.
rection, considering a loop circuit including the windings
P-l and S-2 with the lamp, the numerical values of the
voltages will be additive to a great extent, the degree de
pending upon the phase difference between windings.
As the brush 44 is moved to the left, the effective
secondary winding S-3 becomes greater and greater in
size, and the circuit which includes the primary winding
P-1 and secondary winding 8_2 includes a greater por
tion of S-3 but with the opposite instantaneous voltage
sense, and hence bucking the voltage V--S thereby de
creasing the available RMS. voltage for the lamp L
and hence decreasing the intensity of its light.
As thus far described the circuit is known. The ad
dition ot the peaking circuit 18 completely changes the
apparatus, not only because there is an added structure
and added function, but also because the ordinary func
tions are substantially altered.
`Instead of connecting the brush 44 directly to the ter
minal T-S of the secondary winding S-2, the peaking
The primary winding P-1 has a closely coupled power
circuit 18 is interposed. This comprises a transformer
factor secondary winding S-1 connected thereto at the
terminal T-3, the right hand end of the secondary wind 25 54 having three windings thereon~--a primary winding
P-3, a secondary winding S~4 and a secondary winding
ing S-l being designated as the terminal T-4. There is
S-S. The windings are connected electrically end to end
also a closely coupled filament winding F~1 whose termi
providing the terminals T-10, T-ll, T-12 and T-IS,
nais are T-l and T-2, the latter being common with the
with the first two windings mentioned closely coupled, but
left hand end of the primary Winding P-1. As a matter
of fact, the three windings F-l, P-i and S-l normally 30 with the third winding S-S separated from the other
are part of a continuous coil, with the various terminals
brought out as taps. The leads 22 and 24 are connected
to the terminals T~1 and T-Z to permit the filament Wind
ing F-l to serve the filament 10 and to connect the left
two by a magnetic shunt 56.
The transformer S4 is
illustrated in FIG. 2, and as will be seen there is an un
usually large slot 58 punched in the core within the
secondary winding S-S whose purpose is to provide very
hand terminal of the primary winding P-l to the left 35 narrow saturable flux paths 60 so that a very narrow and
high voltage peak will `be produced in a manner to be
hand terminal lof the lamp L. The power factor con
described. The terminals 'I2-10 and T-ll are connected
denser 'C-l is connected across the primary winding P-1
respectively to the leads 3o and 34 so that the voltage
and secondary winding S-l from terminal T-2 to T-4.
which energizes the primary winding P-S is the voltage
These connections are by way of example as the filament
winding F-l may be included as part of the primary and 40 which is subtended in the effective secondary winding
S-S by movement of the brush 44. The greater the
the power factor correcting circuit of C-1.
voltage across the secondary winding S-3 the greater the
The secondary winding S-2 and the filament winding
voltage energizing the primary winding P-S and hence
F-2 are separated from the other windings of the trans
the greater the voltage ?peak which will be produced.
former 46 by a shunt 52 so that the transformer 46 in
effect is a high leakage transformer providing good bal 45 lt will be seen, however, that the greater the voltage
across the effective secondary winding S-3 the smaller
lasting for the iiow of current after the lamp L is ignited.
the R.M.S. voltage available to the lamp L, and hence
If desired, the filament winding F-Z may be wound on
this arrangement provides a peak voltage which varies
top of the primary. The terminals of the windings S-Z
inversely as the amplitude of the R.M.S. voltage applied
and F-2 are T-S, T-6 and TJ�. The leads 26 and 28
are connected to the terminals T-6 and T-T respectively, 50 to the lamp. The winding S-?4 is in autotransformer
so that the filament Winding F-Z serves the right hand
additive relationship with the primary winding P-S being
iilament 12, while the secondary winding S-2 has its right
connected therewith at terminal T-ll and closely cou
pled therewith. Actually, it is Wound in the same window
of the transformer core as the primary winding P--3.
hand end connected to the right hand end of the lamp L.
The left hand terminal T-S of the secondary winding
The secondary winding S-S of the transformer 54 is
S-Z is not connected directly to the primary winding P-1, 55
connected in autotransformer relationship with the pri
but instead is connected through other intervening com
mary winding P~3 and the additive secondary winding
ponents. The lead 38 connects with this terminal T-S.
S-� but is in voltage opposition to both of these. The
There is provided a variable transformer 16 which com
prises a winding P-2 connected across the line from ter
minal T-S to T~9 so that line voltage is applied thereto.
The wiper or =brush 44 connects with the lead 34 and
arrows indicate this at V-PK, V-玈K and V-SB. The
instantaneous voltage sense of the secondary winding
S-S is additive to the voltage V-S of the winding S-2
ibut. huclied by the voltage of the winding S-4. lf the
picks of� a portion of the winding P-2 to the right of the
circuit is traced `from the terminal T-6 to the terminal
brush which is used to oppose the voltage of the secondary
T-2, it will follow the path through the various wind
winding S-2 and the primary P~1 and hence this right
hand portion of the winding P-Z may be considered a 65 ings: first through the secondary winding S-2 to terminal
T15 and the lead 33 to the terminal T-13, through the
secondary winding S~3. Its voltage obviously will vary
secondary winding S-S additively to terminal T~12,
from zero when the `brush is at terminal T-9 to line
through the winding S-�bucking to the terminal TA1,
voltage when the brush is at terminal T-8. The in
through the lead 34 to the brush v44, through the sec
stantaneous polarity of the variable transformer 16 is
chosen to have a direction which is as shown by the ar 70 ondary winding S-3 bucking to the terminal T-9, through
lead 32 to the terminal T-3, through the primary wind
row V~-V alongside the winding P-2, and the instan
ing P-l additively to the terminal T-2.
taneous relationships of the other windings discussed thus
Obviously when the brush 44 is at terminal '119, there
far as shown by the arrows V--P for the primary voltage,
will be no primary voltage V-PK and none developed
and V-S for the voltage of the secondary winding S-Z.
Note that if the brush 44 is at terminal T-9 the voltage 75 in the secondaries S-4 and S~5 except that which may
3,091,720
7
8
be due to the passage of current resulting from the sec
that the minimum of R.M.S. voltage is available for
operation of the lamp L when the lamp is connected but
with a maximum of peaking voltage. The entire line
voltage is across the primary winding P-3 to ?give the
ondary S-2. There will be practically no peaking volt
age, While the R.M.S. voltage for the lamp L will be
maximum.
When the brush 44 is at terminal T-8, there will be
maximum primary voltage across winding P-3 and a maxi
mum of peaking voltage available, while the R.M.S. volt
maximum of peaking effect from the secondary winding
S-5. The peak produced is shown at 64 at an amplitude
of Ep volts but in effect the voltage wave consists of a
small sine wave indicated by the broken line at 66 of
age available at the lamp L will be a minimum.
The peak voltage which will be described in some de
peak amplitude Es with the peak Em, superimposed there
tail, is developed in the secondary winding S-S by virtue
on.
of the construction of the transformer 54, and this is
what is desired, but there will also be some R.M.S. volt
age developed in the winding S-S as well. The secon
secondary winding S-Z and the peak `64 is provided by
The sine wave 66 is the voltage provided by the
cycles per second. It has been found that this expedient
sharpens the pulse and therefore provides additional ex
the peaking circuit. The intermediate conditions result
in a peak voltage which is dependent upon the position
the peaking circuit 18. The analysis is not as simple as
set forth, since there are probably other factors which
enter, but the primary contributions are made by these
dary winding S-4 being bucking will develop an R.M.S.
two parts of the apparatus.
voltage which tends to cancel the R.M.S. voltage de
In FIGS. 5, 6, 7 and 8 the same voltage waves illus
veloped in the winding S-S so that only the maximum of
trated in FIG. 4 have been modified because of move
peak voltage is obtained from the peaking circuit l18.
ment of the brush 44 to the right to different positions
The ?function of the primary Winding P-3 is to develop
along the length of the variable transformer 16. In FIG.
the proper value of voltages in S-4 and S-?5. The volt
age V-PK has little or no effect upon the total voltage 20 5 the ?brush 44 is at about the 25% position along the
winding, in FIG. 6 it is about half way, in FIG. 7 it is
applied across the lamp L.
at approximately 75% of the way, and in FIG. 8 the
It will be noted that there is a capacitor C-2 connected
brush 44 is at terminal T--9. It will be noted that the
across the secondary winding S-S from terminal T-12
amplitude Em, of the peak portion 66 decreases from
to terminal T-13. This capacitor is chosen to tune the
circuit to provide a ringing effect. The harmonic chosen 25 position to position until in FIG. 8 where the brush is
at terminal T?9 there is no voltage being applied to the
is preferably above the fifth harmonic of the frequency
primary winding P~3 and hence no peak is generated by
of the line, such as for example, a frequency of 300
tent to the controllable -range of the apparatus. In other 30 of the brush 44.
It will also be noted that movement of the brush 44
from terminal T-?S to terminal T--9 results in a gradual
words, the dimming can carry the brilliance of the lamp
to a lower value without losing the ability to re-ignite,
and without flicker, if the ringing arrangement is used.
Additionally, but of no lesser importance is the fact that
the lamp is subjected to a repetition of high voltage 35
pulses instead of one, and hence is more likely to ignite.
voltage available for the lamp.
Most important, however, is the fact that the peak volt
In order to demonstrate the manner in which the
apparatus has `been found to operate, and without com
age Ep of the total voltage wave across the terminals
T-2 and T-6 is practically the same in every case. The
increase of the amplitude of the voltage wave provided
?by the ballast 14, and hence an increase in the R.M.S.
limiting oase is that of FIG. 8 where the peak voltage Ep
mitting the invention to the theory of operation which
may be used to explain the results, graphs of voltage 40 and `the peak of the R.M.S. wave Es are substantially the
same, and there is no detectable peaking effect.
wave shapes are illustrated in FIGS. 4 through 9.
In FIGS. 4 through 8 there are illustrated the open
circuit voltages across the lamp L taken from the termi
In the actual circuit, the peak and R.M.S. voltages
were measured at the following values:
nals T-Z to T---6, with the lamp out of the circuit. These
voltage waves are such as would be encountered in a cir
45
Fig.
Peak Ep
RJLS.
cuit which is designed for use with a rapid start T-lZ
駏orescent lamp of 40 watt rating. This lamp is com
mercially available and is well suited for use in dimming
circuits because of the continuous flow of current in its
275
28D
305
3l()
125
157
190
23()
filaments.
315
'28()
Normally `it ignites at 250 volts, and oper
ates at its rated current of 430| milliamperes with a re
quirement of about 105 volts R.M.S. to remain ignited.
Ignition and re-ignition of the lamp depends wholly
In FIG. 9a there is illustnated the voltage wave of the
voltage across the secondary winding S-S from terminal
upon the voltage initially applied thereto or applied be
T-12 to T-13 with the condenser C-Z disconnected, and
tween half cycles and hence the criterion of ignition is the 55 in FIG. 9b the same voltage is shown but with the con
peak voltage applied to the lamp. If a sufficient peak
denser in place. The voltage in FIG. 9a is made up of
voltage is applied to the lamp, the lamp can operate at
a peak 64 superimposed upon a low amplitude sine wave
very low currents and hence at very low light intensities.
of small R.M. S. value, but this R.M.S. voltage is actually
The invention herein is primarily concerned with the
bucked out by the secondary winding S-4 in the circuit
ignition of the lamp, and hence is intended to provide 60 so that it will not add to the R.M.S. voltage produced
best conditions of peak voltage to enable the low inten
by the ballast 14 at low intensities of light. In actual
sities desired to be reached without extinguishment and
values, the peak voltage Em, measured 140 volts while
without flickering. This is brought out in the voltage
the R.M.S. of the wave 68 measured 48 volts.
waves shown in FIGS. 4 through 8. The left hand por
The above values are approximate, and are intended
tion a of each figure `is the voltage across the terminals 65 to emphasize the fact that the peak voltage of the wave
T-Z and T-6 with the condenser C-Z not connected,
applied to the lamp is quite substantial even at conditions
While the right hand portion .b of each figure is the
of very 10W intensity, and as the R.M.S. voltage decreases
voltage across the same terminals but with the condenser
the peak supplied by the peaking circuit increases and
C-Z in circuit as shown. These voltage wave shapes are
vice versa.
substantially those which will appear on a cathode ray 70
The invention contemplates the addition of the con
oscilloscope. The differences in the amplitudes and con
denser C-Z in order to cause the peaking circuit to ring
tigurations from figure to figure are due to the position
at a frequency which is several times the line frequency.
of the brush 44.
As stated, this new frequency is preferably tive times or
In FIG. 4, the brush 44 is. disposed at the extreme left
more the line frequency. The result of this ringing,
hand end of the variable transformer winding P-Z so 75 which is a form of resonance, is that each pulse triggers
3,091,720
10
the ringing circuit to produce a multiple pulse at every
half cycle. This is seen in the modified form of the
voltage wave of each of the figures at b. The resulting
The windings P-l, S-l and F-l are mounted on the
left hand side in the window 70 upon the central wind
ing leg 72. The windings 8_2 and F-Z are mounted in
multiple pulses are of amplitudes including several that
are higher than peak voltage otherwise would be. In
the voltage wave of FIG. 4b for example, the peak volt
age Ep was 35 volts higher than the peak Ep of FIG.
the right hand window 74 upon the central winding leg
72. The shunt 52 is formed by the inward projection
76 of the outer rectangular framing portion 78 and the
outward extensions 80 of the central winding leg. These
are juxtaposed and spaced apart to provide suitable non~
4a. This increased peak voltage was manifest in volt
ages produced at other positions of the brush as well,
magnetic gaps at 82. In construction, the windings are
but as the peak produced by the peaking circuit 18 de 10 pre-formed, are engaged over the central winding leg 72,
and the resulting assembly is forced into the framing part
creased, so did the excursions of the pulses caused by
78 with the ends of the winding leg 72 matingly engag
ringing as well as their amplitudes. In FIG. 5b for
ing the bridging yokes of the framing portion 78 at 84
example, the peak voltage of the wave was the same
and 86.
as in FIG. 5a and the excursions of the ringing pulses
Variations in this construction are feasible. For ex
were of no consequence. It should be appreciated. 15
ample, the core may be formed of T and t. shaped parts
however, that this was a condition of dimming control in
held together with clamps.
which the problem of ignition and reignition of the lamp
Obviously the cores are formed of stacked steel lamina
tions secured together as by rivets or the like.
intensity.
The transformer 54 is of the same general physical
20
construction as the transformer 46 in the respect that
FIG. 9b is a voltage wave which shows the effect
of the ringing circuit at maximum peaking voltage with
it is formed of stacked laminations of electrical steel,
has a central winding leg 88, an outer framing part 90,
the brush 44 at terminal T'S.
windows 92 and 94 which mount the windings, the shunt
The measurements and wave shapes which have been
was of no importance. The intensity of the lamp was
substantially above the critical situations of very low
25 56 formed by extensions and projections and providing
discussed above have all been considered at open cir
the gaps 96, and the mating engagement of the ends of
cuit, that is, with the lamp L out of the circuit. As
mentioned previously, the lamp is essentially a constant
the winding leg with the yokes. The important differ
potential device and is self-regulating, so that a de
crease in the open circuit R.M.S. applied to the lamp
ence between the transformers, and for that matter be
tween the transformer 54 and other transformers, is the
will result in a decrease in the current flowing through
the lamp. The lamp voltage will remain fairly con
stant, while the changes due to decrease in current will
be compensated for by the reactive nature of the ballast
to give the desired results.
Measurements were made of various parameters dur 35
presence of the large slot 58 at the particular position that
through the lamp was 3.2 milliamperes, the peak voltage
inch, or about 60% of the width of the central winding
it is located.
The dimensions of the core of the peaking transformer
54 may be studied to aid in an understanding of the opera
tion thereof. The width of the central winding leg at
K in the practical example illustrated was .831 inch.
The width of the slot 58 was .721 inch indicated at l
ing operation of the lamp for different settings of the
thereby leaving the narrow flux paths 60 on each side,
brush. At or quite close to the terminal T-S the lamp
having a width of .055 inch, indicated at M. This repre
barely glowed and produced a minimum light output
sents a reduction in width of the central winding leg
measured on a light meter with an arbitrary unit of l,
while with the brush at terminal T� the lamp glowed 40 of about 87%. Also the length of the slot 58 which
is considered in the direction of the flow of primary llux
in full brilliance with the same meter giving a reading
through the central winding leg, is shown at N as l/2
of 90 units. At the minimum setting, the current flowing
was 295 volts and the R.M.S. voltage was 135.
At the
eg.
The effect of the very narrow sections 66 is to cause
maximum light setting, the current flowing through the 45
the generation of a very high 籥nd narrow voltage peak due
lamp was 260 milliarnperes, the peak voltage had dropped
to the sudden saturation of the steel in these narrow sec
to 186 volts and the R.M.S. voltage had dropped to
tions. Upon saturation of the steel no voltage is gen
110 volts.
erated in the secondary winding S-S because the length
Between these two extremes, there were proportional
changes in the parameters. Generally they were as fol 50 of the slot 58 is sufficient to inhibit any increase in iiux.
The gene-ral proposti-ons used in the particular structure
lows:
were found to be optimum, with no increase in length N
being effective to improve the peaking. Decrease of this
Setting nl? Brush
Firm ________________________________ ._
? ..
'
�
.
I-Lamp
R蚆S.
3.2
Light
dimension from the 1/2 inch used was found to widen the
55 peak pulse and add 玹o the R.M.S. voltage generated in
13s
1
81
122
2s
152
121
59
192
11s
7
260
11u
90
The settings of the brushes as set forth above are
the same approximately as they were for the settings
of the figures identified. The lamp current was meas
the secondary winding S-S.
Moving the slot 58 away
from the shunt 56 will :result in an increase in the R.M.S.
voltage generated in the secondary winding S-S because
of the increased opportunity for fringing of flux from
60 fthe steel that is disposed between the slot 58 and the
shunt 56. Obviously it is most advantageous to have as
little steel between the shunt land fthe slot as practical
and hence the end of the window 92 and ithc edge of .the
slot 58 closest to the primary winding P-3 are substan
and is given in milliam-peres. The R.M.S. is the value 65 tially coincident.
The shunt 56 is of importance because it provides the
across the lamp. The light was measured with a photo
return path for primary flux when the flux paths 60 are
electric cell connected across a galvanometer, and the
saturated; it provides the loose coupling between the pri
units were those of the meter and are arbitrary. The
mary P-S with its secondary S-4 `and Ithe secondary wind
peak voltages are not recorded since they varied con
siderably, but since these conditions are those of the 70 ing S-S to help regulate llow of current through the lamp
L; it provides a high leakage reactance and hence an in
lamp operating these readings would have no significance.
ured in the lead 38 in order to obtain the total flow,
Attention is now invited to FIGS. 2 and 3.
These
籨uctance which 籨ecreases the slze of condenser C-2 neces
sary to achieve the ringing resonance desired in the peak
show the transformers 54 and 46 respectively. The
ing circuit 18; and it prevents excessive exciting current
transformer 46 is not unusual in design, being merely
a high leakage reactancc forced core type of structure. 75 in 玹he primary which otherwise would occur with a satu
3,091,720
12
1l
the R.M.S. voltage developed in said second secondary
rating portion under the secondary winding S-5. Thus,
winding.
the number of turns required to achieve a high peaking
voltage is `less than otherwise would be needed.
The practical example which has been referred to here
in was successfully 籵perated without iiickering and with
complete control and ease of re-ignition to light intensi
ties of extremely low value. The physical characteristics
of the apparatus are given hereinafter.
From the dimensions applied to the transformer 54, the
proportional dimensions of it and the transformer 46
3. Apparatus as claimed in claim 1 in which the second
secondary is tuned to a frequency which is a multiple of
the frequency of the A.C. source.
4. Means adapted for assuring the ignition of a fluore
scent lamp at conditions of a low lamp current, the said
means adapted to be associated and connected into an
environment which includes an A.C. power source, a
variable transformer `connected across the source and in
may be ascertained, since both `are drawn to the same
cluding an adjustable contact to be moved to different
scale. The overall length of the core of ?the transformer
54 was 4 inches, and its width slightly over 2 inches. The
voltage output positions, a high :leakage reactance trans
former having primary and secondary windings with the
variable transformer output connected between the pri
length of the core of transformer 46 was 5 inches and its
width the same as the core of the transformer ?54. This
mary and secondary windings and arranged to provide a
variable voltage bucking the voltage of the secondary
depending upon the position of the contact, the primary
conveniently enabled both transformers `to be potted in a
long narrow canister. The laminations were stamped
from 24 gauge electrical steel and the transformer had a
1%: inch stack while the transformer 46 had 籥 .625 inch
stack. The coil data for the various windings follows;
Turns
and secondary windings being connected in auto-trans
former relationship across the lamp, the first mentioned
20 means including a voltage peaking transformer connected
with the output of the variable transformer and arranged
to superimpose a voltage peak upon the R.M.S. voltage
G auge wire
g--
s1
47
zal@
P_
1, 045
281i�
P-
ss
applied across the lamp, the amplitude of said peak vary
ing inversely with said R.M.S. voltage.
5. Means as claimed in claim 4 in which the peaking
transformer is tuned to a multiple of the frequency of
the source so as to provide a ringing voltage peak.
s1, o45
est�
6. In a fluorescent lamp dimming circuit connected
s1,061
2a
s22o
29
across an A.C. line and having a high leakage reactance
s1,120
2s
30 transformer for providing an R.M.S. voltage across the
lamp, a variable transformer for varying the R.M.S.
The condenser C-1 was 3.7 microfarads with a rating
voltage, and a peaking circuit for superimposing a volt
of 230 volts A.C. and the condenser C-2 粀as .2 micro
age peak upon the R.M.S. voltage, means for multiplying
fanad with `a 118 volt A.C. nating. The gaps 82 and 96
the number of pulses provided by the peaking circuit.
35
were .029 rand .01175 inch respectively.
7. A structure as claimed in claim 6 in which the means
The variable transformer was of a well known com
for multiplying the pulses comprises a ringing circuit built
L閟
25
29
mercially available construction, designed to be connected
tto a conventional 120 volt A.C. line and provide any de.
sired voltage between its brush 44 and one of its termi
nals within the range zero to 120.
lt is believed that the invention has been fully ex
plained suiiiciently to be understood and applied by those
into said peaking circuit.
8. In a ballast apparatus with a dimming control for
igniting and operating a iluorescent lamp at different light
40 intensities `from `an A.C. source and which includes a high
leakage reactance transformer connected to the lamp for
applying an R.M.S. voltage to the lamp and a variable
voltage output device connected to oppose the R.M.S.
skilled in this aint and it is desired to point out that varia
tions can be made without in any way departing from
voltage applied to the lamp and having means for varying
the spirirt or scope tof the invention ias defined in the ap 45 its output; a peaking circuit connected in circuit with
pended claims.
said high leakage reactance transformer `for applying a
What it is desired to secure by Letters Patent of the
peak of voltage superimposed upon said R.M.S. voltage
to aid in igniting the lamp, said peaking circuit including
United States is:
1. A device of the character described which includes
a peaking transformer having a primary winding
a ballast for igniting and openating a gaseous discharge 50 connected to be energized by the output of said variable
lamp adapted to be energized by a source o-f A.C. power
voltage device so that the said primary winding is ener
gized by output voltages which vary inversely as the
and ?adapted to be connected with a variable output trans
R.M.S. voltage applied to said lamp, a peaking secondary
former, la peaking transformer connected with the ballast
winding loosely coupled to the primary winding and
and `adapted to be connected with the variable output
transformer, said ballast including a high leakage reac 55 adapted to have the peak voltage generated therein, and
tance ?transformer with first primary and first secondary
a magnetic core mounting both the primary and second
windings loosely coupled and the windings having leads
ary windings and having a large slot therein under the
for connecting the `same to the said lamp, the peaking
secondary winding to provide saturation at the voltage
transformer including second primary and second sec
peaks of the `applied voltage to generate a sharp narrow
ondary windings loosely coupled and with the second 60 voltage peak.
primary winding having leads for connecting same to be
9. A peaking circuit as claimed in claim 8 in which
energized by the variable output transformer with a volt
there is another secondary winding on the core of said
age that varies inversely as the voltage to be applied
transformer, closely coupled with the primary winding
across the lamp, and with the second secondary winding
and adapted to be connected in the lamp circuit bucking
having means for generating a peak therein and being 65 the peaking secondary winding to offset any R.M.S. volt
connected in series with said first secondary winding and
age developed in said 駌st secondary winding.
having an auto transformer connection with that lead of
10. A peaking circuit as claimed in claim 8 in which
there is a condenser in circuit with said peaking secondary
the variable output transformer, whereby the peak ampli
winding tuning same to a multiple of the said A.C. source
tude generated in said second secondary will vary inversely 70 to cause a ringing of said peak voltage.
as the R.M.S. voltage applied to said lamp.
l1. A peaking transformer for use in a fiuorescent
2. Apparatus as claimed in claim l in which said peak
lamp dimming circuit .and adapted to be connected to
ing transformer has a third secondary winding closely
superimpose a peak voltage upon the R.M.S. voltage
coupled with the second primary winding and in voltage
across the lamp, and the dimming circuit including a
said ysecond primary winding adapted to be connected to
opposition to the second secondary winding to buck out 75 variable voltage device to change the R.M.S. voltage ap
3,091,720
13
plied to the slamp, the peaking transformer comprising
an elongate laminated iron core having an outer framing
portion and a central winding leg, windings encircling
the central winding leg and comprising a primary winding
?I4
R.M.S. voltage which may occur across the lamp results
in an increase in voltage applied to said second primary
winding and hence in an increase in the peak voltage
produced in said peaking secondary.
at one end of the leg and a secondary winding at the
17. A dimming circuit as claimed in claim 16 in which
other end of the leg with a shunt disposed between the
Ithere is a third secondary winding closely coupled with
said second primary winding and connected in series with
windings and having non-magnetic gaps therein, windows
formed in the outer framing portion to accommodate said
said peaking secondary winding but in voltage opposition
windings, the primary winding adapted to be connected
thereto whereby to compensate for R.M.S. voltage pro
to the variable voltalge device so that fit is energized in 10 duced by said peaking secondary winding.
accordance with the voltage output of said device, the
18. A dimming circuit as claimed in claim 16 in which
secondary winding adapted to be connected in the lamp
there is a condenser tuning said peaking secondary wind
circuit to the exclusion of the primary winding whereby
ing to provide a series of pulses at each half cycle instead
the voltage generated in said secondary winding is adapted
of a single peak.
to be superimposed upon the R.M.S. voltage applied to 15
19. Apparatus for use with a variable voltage device
the lamp, said central winding leg having a slot therein
connected across a source of A.C. power for igniting and
beneath the secondary winding and having its transverse
operating a gaseous discharge lamp with variations in
edge closest to the shunt substantially coincident with
intensity of light caused by adjustment of the variable
the end of the secondary winding thereat, having a length
voltage device to provide different voltages, and the volt
along the central winding leg sufficient to prevent flux 20 age device including a brush movable to different tapped
from being produced therein when the narrowed portion
positions, 籺he said apparatus comprising: a high leakage
of the leg is saturated, and having a dimension transverse
of the leg to cause fast 駏x saturation at the peaks of the
reactance transformer including at least a primary wind
ing and a secondary winding and means for connecting
the primary winding across the said source one side of
applied voltage.
12. A peaking transformer as claimed in claim il in 25 the primary winding having means for connecting the
which the slot has dimensions to reduce the flux path
winding to one terminal of said gaseous discharge lamp,
through the central winding leg 籦eneath the secondary
means for connecting the second side of the secondary
winding by substantially more than tifty percent.
winding to the second terminal of the lamp, a connection
13. A peaking transformer as claimed in claim 11 in
to the second side of the secondary winding adapted to
which the length of the rslot along the central winding 30 extend to the brush ofthe variable voltage device whereby
leg is substantially more than 駀ty percent of the width
when the primary and secondary windings are connected
of said central win-ding leg.
across the lamp, and the primary winding is connected
14. A peaking transformer as claimed in claim 11 in
acnoss the line, and the second side of the secondary wind
which there is another secondary winding mounted in
ing is connected to said brush, the primary and secondary
the same windows as the primary winding and adapted to 35 windings will be connected in autotransformer relation
be connected .in voltage opposition to the first secondary.
across the lamp but with the resulting voltage determined
15. A peaking transformer as claimed in claim l1 in
which there is a condenser tuning the said secondary
to cause the peak produced by the said transformer to
by the position of said brush, a peaking circuit in the con
nection of the second side of said secondary for super
imposing a peak upon the R.M.S. voltage generated by
40 said transformer to aid 籭n starting the lamp, and having
be a ringing one.
16. A dimming circiut for ballasting and controlling
means for varying the amplitude of the peak inversely as
the operation of a fluorescent `lamp and the circuit adapted
the R.M.S. voltage produced due to changes of the posi
to `be connected across a source of A.C. power and a
tion of the brush.
variable output voltage device having opposite end con
20. Apparatus as claimed in claim 19 in which the
nector means for connecting the same across the source 45 peaking circuit also has means for bucking out the R.M.S.
and having a lead connected to a brush which is variable
voltage developed therein.
so that positioning the brush along the exposed contacts
21. Apparatus as claimed in claim 19 in which a ring
of the variable voltage output device will provide a varia
ing circuit is provided in connection with said peaking
ble voltage from said lead to one or the other of the
circuit to render the peak a plurality of pulses.
opposite end connector means, said circuit comprising, a 50
22. Ballast 籥pparatus for variably controlling the in
ballasting transformer having a first primary winding and
tensity of illumination from a fluorescent lamp energized
a iirst secondary winding loosely coupled one relative
by an alternating power source which comprises, a vari
to the other and the first primary winding having means
able transformer having first and second terminals con
籥dapted for 籧onnecting the same 籥cross the source, one
nected across said source and a variable tap positioned
end of the first primary winding adapted to be connected 55 intermediate said terminals, a lamp ballast comprising a
lo a terminal of said lamp, a peaking transformer having
first primary winding, a 駌st secondary winding connected
a second primary winding and a loosely coupled peaking
thereto and a second secondary winding, a magnetic core
secondary winding 玜nd means for providing a sharp peak
for said last named windings, said core having a magnetic
of vol-tage in said peaking secondary winding for each half
shunt positioned between said first and second secondary
cycle of voltage applied to the second primary winding,
windings, said primary winding being connected across
the second primary winding ladapted to be connected from
said first and second variable transformer terminals, said
said brush lead to the one of said end connector means,
primary winding and said second secondary winding each
said one end connector means adapted to be connected
having one end terminal connected for energizing op
to the second end of said first primary winding, one end
posite electrodes of a iluorescent lamp, and in combination
65
of said 駌st secondary Iwinding adapted to be connected
therewith, a peaking transformer having a second primary
to the second terminal of said lamp and the second end
winding 籥nd third and fourth secondary windings all
of said 駌st secondary winding being connected in series
connected in series, a common core for said last three
with said peaking secondary winding and adapted to be
named windings, said last named fourth secondary wind
connected in series with said brush, the two secondary 70 ing being wound in opposing magnetic relation to said
windings `being additive when in circuit across said lamp
second primary winding and said third secondary winding,
with said 駌st primary winding, but that portion of the
said core having a magnetically saturable reduced mag�
variable voltage device between said brush and said one
nctic cross-section dispose-d beneath said magnetically
end connector means adapted to be in voltage opposition
opposed fourth winding means connecting said second
to said two secondary windings, whereby decrease of 75 primary in series between said variable tap and said
3,091,720
15
second variable transformer terminal, means connecting
said fourth winding with a free terminal of said second
16
in said fourth primary winding for superposition on said
iirst wave thereby to ignite said lamp.
secondary winding, means connecting a common terminal
of `said first primary and said first secondary with said
second terminal, and means connecting the opposite ter
minals of said iirst primary and `secondary in operative
relation, whereby a first energizing wave is applied to said
first primary, said 駌st wave having an amplitude propor
tioned to the positioning of said tap between said term@
nais, and an inversely proportioned pulse is generated
References Cited in the file of this patent
UNITED STATES PATENTS
2,829,314
2,830,232
2,864,035
Vrandenburgh _________ __ Apr. l, 1958
Carpenter et al _________ __ Apr. 8, 1958
Davis ________________ __ Dec. 9, 1958
Notice of Adverse Dee韘ion 韓 Interference
In
Interferenc�
No. 94,236
involving
BALLAST APPARATUS
WITH
DIMPatent; N o. 3,091,720, E. J. Huberty,
adverse to the pa-tentee was rendered J an. MING
8, 1965, CGNTROL,
as to claim 19.駈al
[Oficial Gazette Febr/amy 23, 1965.]
judgment
Disclaimer
Chicago, Ill. BALLAST APPARATUS
3,091,7Q0.--E!mer
J. Hubert? ONTROL.
,
裋ITH DIMMING
Patent dated
MayTransformer
Q8, 1963. Dls
Advance
00.
claimer filed Dec. 14, 1964, by the assignee,
Hereby enters this disclaimer to claim 19 of Suid patent.
[Oj铒eial Gazette Marr-h 30, 1.965.]
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