Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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SCREW~IN TYPE LI~HTING UNIT HAV~NG A
CO~VOLUTED TRIDIMENSIONAL FLUORESCEMT LAMP
.
This application discloses and claims a compact
lamp unit which employs a triple-U~bent fluorescent lamp
component o~ the type di~closed and claimed in Canadian
application Serial No~ 365,271, filed November 21, 19~0
o.~ F. W. Hoeh, entitled "Fluorescent Lamp Ha~ing A Tubular
En~elope Of Compact Tridimensional Configuration, And
Method Of M~king Such Envelope", which application is
assigned to the assignee of this application~
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This invention relates to electric lamps and has
particular reference to a compac~ ~luorescent lamp unit
that is adapted for use as a direct replacement ~or incan
descent type lamps in lighting fixtures employed ~or resi~
dential and commerci~l illumination.
Fluorescent lamp un~ts ha~ing integral circui~
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and base components which permit the unit to be screwedinto and operated in the sockets of lighting fixtures that
are designed for incandescent type lamps are generally
well known in the art. A lamp unit of this type having a
cylindrical envelope that contains concentric annular
partitions (or which is made ~rom tubing that is bent upon
; itself to provide a U-shaped bulb~ is disclosed in U.S.
Patent 3,551,736 granted December 29, 1970 to Doehner. As
disclosed in Figure 5 and at lines 24-30, column 2 of this
patent, if a tubular U-shaped bulb is used as the envelope
it may be additionally twisted into spiral shape or re-
doubled on itself to provide a generally M-shaped enve-
lope. A lamp assembly having adapter means which accommo-
dates a conventional straight tubular fluorescent lamp and
contains a ballast transformer that is part of a threaded
base member which permits the lamp assembly to be screwed
into an incandescent lamp socket is ~disclosed in U.S.
Patent 3,815,080 granted June 4~ 1974 to F. Summa.
According to a more recent development, a screw-
in type fluorescent lamp bulb is provided with integralballast means that is disposed in telescoped relationship
with an envelope that defines a discharge space of flat
toroidal shape of similar configuration. A lamp unit of
this type is disclosed~jind.U S. Patent 3,953,761 granted
April 27, 1976 to T. ~ ~d~e. Another fluorescent lamp
assembly of this general type having a tapered cylindrical
envelope of molded glass that defines a helical-shaped
discharge channel and accommodates a ballast component is
described in U.S. Patent 3,899,712 issued August 12~ 1975
to H. Witting.
An electrodeless fluorescent lamp unit of the
screw-in type that is energiæed by high frequency energy
produced by a self-contained radio-frequency oscillator
and ferrite core is disclosed in U.S. Patent 3,521,120
granted July 21, 1970 to J. M. Anderson.
Electric discharge lamps having tubular enve-
lopes which are bent into various shapes to provide con-
centrated sources of light are also generally well known
3 ~18~242
in the art. A sodium-vapor discharge lamp of double-ended
construction having an envelope formed from a vitreous
tube that is folded or bent upon itself twice to provide
three straight segments that are disposed in triangular-
spaced relationship is disclosed in British Patent 854,745published November 23, 1960 (Figures 3 and 4 embodiment).
A luminous discharge tube designed for advertising and
display purposes (or for use as a beacon light) and having
thimble-like electrodes 2nd an envelope which is formed
from glass tubing bent upon itself eleven times to provide
a corresponding number of conjoined U-shaped sections is
disclosed in U.S. Patent 1,898,615 granted February 21,
1933 to Byrnes. A plug-in type discharge lamp having a
tubular envelope that is bent upon itself three times to
provide a multi-segment envelope which is disposed within
a heat-conserving double-walled enclosure is disclosed in
! U.S. Patents Nos. 2,001,511 and 2,2Q0,940 granted to
Uyterhoeven et al.
Fluorescent lamps having "three-dimensional"
type envelopes that are formed by coupling several arcuate
lamp components together or interconnecting several
straight tubular bulbs in "bundled" configuration are also
known in the art and are disclosed in U.S. Patent
2,652,483 (I.~idig et al.) and U.S. Patent 3,501,662
(Plagge), respectively.
SUMMARY OF THE INVENTION
W~.ile it has long been realized in the prior art
that the physical size of a fluorescent lamp could be
decreased to provide a brighter light source by using par-
titioned or bent multi-segment tubular envelopes, lamp
units employing such concepts were impractical from a
commercial standpoint since they required special elec-
trode and seal structures and/or envelopes that were very
difficult and expensive to make on a mass production
basis. In many cases the envelopes were also so config-
ured that the physical dimensions of the lamp unit which
contained integral circuit components and was fitted with
a screw-in type base component were too large to permit
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the lamp unit to be used in lighting fixtures and sockets
designed for incandescent lamps. Another serious short-
coming of the prior art screw-in type fluorescent lamp
units was that, when they were made small enough to fit
into incandescent lamp fixtures and sockets, they were
unable to generate a sufficient amount o~ light to provide
illumination comparable to that obtained with an incandes-
cent lamp, or to produce such illumination without radio-
frequency interference and at a level of efficiency that
would justify the added initial expense of such lamp
units.
The foregoing manufacturing problems and commer-
cial disadvantages are overcome in accordance with the
present invention by providing a screw-in type lamp unit
which contains a fluorescent lamp that has a tubular
t;n)~n~ ,'a ~d/ ~- Cc~ JOIC~ ,4~
envelope of ~ e-~gee~7$+~e~ con~lguration. The enve-
lope is of triple-U-bent construction and so shaped that
it not only permits conventional stem and electrode compo-
nents to be employed but physically accommodates circuit
means and a threaded base in such a manner that the re-
sulting lamp unit is small enough to be used in sockets
and lighting fixtures designed for incandescen-t type lamps
and produces light of an intensity comparable to that
obtained from such incandescent lamps.
Since the fluorescent lamp component employed in
the new lamp unit is basically a conventional straight
tubular fluorescent lamp that has been bent into convo-
luted form, it employs the same components and basic
technology used to manufacture standard type fluorescent
lamps and thus can be made at a reasonable cost and will
have the excellent light output and efficacy, as well as
the long useful life, exhibited by conventional fluores-
cent lamps now being marketed and in use. The improved
fluorescent lamp unit provided by the present invention
accordingly has the requisite physical compactness, light
output, and high level of quality and performance needed
to make it a practical and energy-conserving substitute
for incandescent type lamps.
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: In accordance with one embodiment, the tubularleg segments of the U-shaped sections of the convoluted
fluorescent lamp envelope are arranged in spaced quadran-
gular columnar relationship to provide a central opening
that accommodates an elongated choke ballast and thus
reduces the size of the lamp unit without materially
decreasing its light output. In another embodiment, the
ballast and starter components are located within the base
structure to provide a fluorescent lamp unit that is more
elongated but of smaller width dimension.
Experimental fluorescent lamp units embodying
the present invention and containing integral ballast and
starter components which permit the units to be operated
from conventional 120 volt alternating-current power
outlets have outputs in the order of l,000 lumens and
system efficiencies of approximately 40 lumens per watt
and are compact enough to be used i~ table lamps and
similar lighting fixtures that are employed in homes and
offices and were specifically designed for incandescent
type lamps.
Another important feature of the present inven-
tion is the use of a protective cover or housing which
diffuses the intense light from the convoluted fluorescent
lamp in a pleasing manner and has vent openings that
cooperate with similar openings in the base structure to
permit air to circulate through the lamp unit during
operation and thus dissipate heat generated by the lamp
and circuit components. The resulting convection cooling
of the operating lamp unit is very advantageous since it
prevents the fluorescent lamp and integral circuit compo-
nents from becoming overheated during operation and thus
becoming less efficient, despite the compactness of the
lamp unit. Such cooling also provides the option of using
convoluted fluorescent lamp components that have higher
light outputs, in the order of 2,000 lumens for example.
BRIEF DESC~IPTION ~ THE DRAWINGS
A better understanding of the invention will be
~ obtained from the exemplary embodiments shown in,~accom-
6 48,242
panying drawings, wherein:
~ igure 1 is a side elevational view of a compactfluorescent lamp unit tha-t embodies the invention, the
convoluted lamp and circuit components being shown in
phantom outline to indicate their locations within the
unit;
.' Fig. 2 is a pictorial view of the triple-U-bent
fluorescènt lamp component employed in the lamp unit shown
in Fig. l;
: 10 Fig. 3 is an exploded perspective view of the
fluorescent lamp unit shown in Fig. l;
Fig. 4 is a cross-sectional view through the
lamp unit alcng line IV-IV of Fig. l;
Fig. 5 is a side elevational view of an alterna-
tive compact fluorescent lamp unit embodying the inven-
tion;
Fig. 6 is an exploded pictQrial view of the
alternative lamp unit shown in Fig. 5;
Fig. 7 is a cross-sectional view of the alterna-
tive lamp unit, taken along line VII-VII of Fig. 5;
Fig. 8 is an exploded pictorial view of still
another embodiment of a compact fluorescent lamp unit
according to the invention; and,
~ igs. 9-11 are longitudinal sectional views of
alternative embodiments of protective cover components for
the compact lamp units.
DESCRIPTION OF THL PREFERRED EMBODIMENTS
While the present invention can be advantageous-
ly employed in various kinds of lamp assemblies that are
suited by virtue of their small physical size and high
brightn~ss for lighting homes or offices, it is particu-
larly adapted for use in conjunction with screw-in type
lamp units that employ low-pressure type discharge lamps
such as fluorescent lamps as the light source and it has,
accordingly, been so illustrated and will be so described.
A compact fluorescent lamp unit 12 embodying the
invention is shown in Fig. 1 and consists of three basic
components--namely, a fluorescent lamp L having a tubular
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envelope 14 of ~que convoluted configuration which
provides a concentrated light source of hig'h efficacy and
brightness as hereinafter explained, a light-transmitting
housing such as a cover C that protectively encloses the
fluorescent lamp L, and a base structure B that is coupled
to the sealed ends of the lamp envelope 14 and holds the
fluorescent ~amp L in assembled relationship with the
cover C and the various integral components of a circuit
which permits the lamp unit 12 to be operated on an alter-
nating-current power source.
As will be noted, in this embodiment the circuit
means comprises an elongated ballast component 15 (that is
located in the space betheen the U-bent sections of the
convoluted fluorescent lamp envelope 14) and a conven-
tional condenser 16 and starter 17 that are connected withthe ballast 15 and the lamp electrodes in the usual man-
ner. The base structure B has a cup-~shaped portion 18
that accommodates and contains the sealed ends of the
fluorescent lamp envelope 14 as well as the condenser 16
and starter 17. The base structure B is terminated by a
suitable electrical connector component, preferably a
threaded base member 20 having the usual insulator 21 and
end contact 22. The threaded base member 20 is of a type
that will fit the threaded sockets designed for incandes-
cent type lamps so that the single-ended fluorescent lamp
unit 12 can be screwed into and be operated in such sock-
ets.
As shown more particularly in ~ig. 2, the enve-
lope 14 of the fluorescent lamp L comprises a vitreous
tube that is bent in a manner such that it has four sub-
stantially straight leg segments 24, 26, 27, 28 that
extend in the same direction and are joined by three
U-bent segments 29, 30, 31. The U-bent segments are of
such curvature and so oriented that the tubular leg seg-
ments are dispos,ed in quadrangular columnar array andspaced from one another. The leg segments and U-bent
segments accordingly form three conjoined U-shaped enve-
lope sections that are located in three different planes
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and define a single discharge chalmel of serpentine con-
figuration that is terminated by leg segments 24, 26. The
envelope 14 is, accordingly, of triple-U-bent tridimen-
sional form and very compact.
As shown, the U-bent segment 31 which consti-
tutes the medial portion of the convoluted envelope 14 has
a tipped-off segment 32 of a glass tubulation that i5 used
to drain phosphor paint from the envelope during the
phosphor-coating operation and ensure that the medial
U-bent section is coated with a uniform layer of phosphor
material. Insofar as the compact fluorescent lamp L
operates at rather high loading, the tipped-off segment 32
affords an additional advantage in the finished lamp since
it defines a cavity inside the envelope 14 that serves as
a "cool spot" and thus functions as a reservoir for con-
densed mercury that controls the mercury vapor pressure
during lamp operation. The leg segments 24, 26 extend
beyond the medial U-bent segment 31 and are hermetically
sealed by conventional stem components 33, 34 which in-
clude the usual tungsten-coil electrodes 35, 36 that are
coated with suitable electron-emission material and con-
nected to suitable conductors such as paired lead-in wires
37, 38 that extend through the respective stems and beyond
the sealed ends of the envelope 14. Each of the stems
have a sealed-off remnant 39, 40 of an exhaust tubulation
which permits the convoluted envelope 14 to be evacuated
and then charged with a suitable fill gas and dosed with
mercury in accordance with standard lamp-making practice.
If desired, non-tubulated type stems can be used
and th~ evacuation, gas-filling and mercury-dosing opera-
tiorls can be dolle through the tubulation extending from
U-bent segment 31.
As will also be apparent to those skilled in the
art, a straight tubular envelope can be phosphor coated,
lehred, and provided with stem assemblies to form a
partly-fabricated fluorescent lamp which can then be bent
into the desired triple~V-bent configuration. The result-
ing convoluted phosphor-coated embryonic discharge lamp
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can then be completed by exhausting, gas-filling, and
mercury-dosing through a tubulation which is provided on
one or both of the stems. With this mode of lamp manufac-
ture, there would be no tipped-off tubulation on the
medial U-bent segment of the fluorescent lamp.
As will be noted in Figs. 1 and 2, the sealed
legs 24, 26 of the envelope 14 extend beyond the medial
U-bent segment 31 and are disposed in side-by-side paired
relationship on the same side of such segment. These are
important structural features of the invention since they
provide an unobstructed space or central opening that
extends upwardly from the base structure B into the
triple-U-bent envelope 14 between the leg segments 24, 26,
27, 28, and a smaller space below U-bend 31 adjacent the
sealed ends of the legs 24, 26. As illustrated in Fig. 1,
the provision of such spaces permits the elongated ballast
component 15 to be placed in telescoped nestled rela-
tionship with the convoluted lamp envelope 14 and provides
room for recessing the condenser 16 and starter 17 within
the base structure B adjacent the sealed ends and beneath
the medial U-bent segment of the envelope. The circuit
components thus constitute integral parts of the compact
lamp unit 12 and are located within its physical confines.
Since the tubular leg segments 24, 26, 27, 28 of
the triple-U-bent envelope 14 extend in the same direction
and are disposed substantially parallel to one another in
quadrangular and columnar-spaced array, the overall con-
figuration of the fluorescent lamp L is such that it is
generally cubical or tetrahedral in character. When the
30 lamp L is energized it thus constitutes a three- .
dimensional source of light which, while very compact,
still has a single discharge channel that is about four
times the height of the envelope 14 and thus permits the
lamp to be operated efficiently at a voltage and current
compatible with the electrical power supplied to homes and
offices.
As indicated in Fig. 1, the width dimension wl
of the lamp unit 12 is governed by the diameter of the
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- circular cup-shaped portion 18 of the base structure B
required to accommodate the cylindrical protective cover C
c and is thus only slightly larger than the width of the
~ convoluted lamp L. The height dimension ~h~of the lamp
;5 unit 12 is determined by the combined lengths of the
convoluted lamp L and base structure B. Due to the
triple-U-bent configuration of the lamp L and the inter-
fitting of the envelope 14 with the circuit components and
cup-shaped portion 18 of the base structure B, the height
dimension ~ ~of the lamp unit 12 is drastically reduced.
While the convoluted lamp envelope 14 can be
made by joining three U-bent sections of vitreous tubing
together, it is preferably formed from a single piece of
lead glass tubing of the kind used for conventional fluo-
rescent lamp bulbs. The glass tubing is bent at theproper points to form the U-bends and is subsequently
!coated with phosphor and provided wit~ stem assemblies,
etc., in the usual manner. The envelope 14 is charged
;with a suitable ionizable medium such as a fill gas and a
measured dose of mercury that are introduced into the
envelope through the exhaust tubes of the stems 33, 34
before they are tipped-off and sealed. A suitable fill
gas is argon at a pressure below about 10 torrs, and
preferably about 3 torrs. The mercury dosage will vary
- 25 according to the physical size of the lamp L and the power
loading at which it is operated but is sufficient to
provide mercury vapor at a partial pressure of from about
6 to 10 millitorrs when the lamp is operated at its rated
wattage, and maintain the mercury vapor pressure at this
level within the lamp throughout its useful life.
Whi:le any suitable phosphor (or mixture of
phosphors) can be used to form the luminescent coating
deposited on the inner surface of the convoluted tubular
envelope 14, in lighting applications where optimum visual
clarity and color rendition of the illuminated objects or
area are required, phosphor coatings which contain a blend
of three phosphors that emit visible radiations in three
different selected regions of the spectr~m (specifically,
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the wavelength regions o~ about 450 nm, 540 nm and 610 nm3
are desirably employed to provide a so-called "prime
color" fluorescent lamp L, pursuant to the teachings of
~e W. A. Thornton in the article entitled "Luminosity and
Color-Rendering Capability Of White Light", Journal of
the Optical Society of America~ Vol. 61, No. 9 (September
1971), pages 1155-1163. As a specific example, a suitable
phosphor blend for a triple-U-bent fluorescent lamp having
such an enhanced light output contains manganese-activated
zinc silicate phosphor, europium-activated strontium
chlorophosphate phosphor, and europium-activated yttrium
oxide phosphor--all of which are well known to those
skilled in the art. Alternatively, the envelope 14 can be
coated with "Cool White" or "Warm White" halophosphate
type phosphors (or any other kind of phosphor or phosphor
mixtures) employed in conventional fluorescent lamps.
As shown more particularly in ~igs. 3 and 4, the
compact fluorescent lamp unit 12 is fabricated by first
inserting the elongated ballast component 15 in nestled
position within the leg segments 24, 26, 27 and 28 of the
convoluted envelope 14 and then connecting the ballast,
condenser 16 and starter component 17 to the insulated
lead wires 37, 38 and socket contacts in the manner illus-
trated in Fig. 3 (a separate insulated conductor 41 being
employed to connect one side of the ballast 15 with the
shell contact of the screw base 20). The end contact 22
of the base 20 is connected by one of the lead wires 37
directly to one of the lamp electrodes so that the ballast
15 is connected in series with the electrodes. The con-
denser 16 and starter 17 are connected in the usual mannerto start the fluorescent lamp L in preheat fashion when
the lamp unit 12 is connected to an alternating-current
power source.
The convoluted fluorescent lamp L and its at-
tached circuit components are then mounted in upstandingposition within the cup-shaped end portion 18 of the base
structure B~ secured to the latter by suitable means (not
shown) such as cement or an interlocking support member
.
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that couples the sealed legs 24, 26 of the envelope 14 to
the base structure, and the conductors 37 and 41 are
fastened to the base contacts by soldering or the like.
The resulting subassembly (consisting of the convoluted
fluorescent lamp L, connected circuit components and
coupled base structure B) is then inserted into the pro-
tective cover C u~til the rim of the cover is firmly
seated within and frictionally held by (or otherwise se-
cured to) the cup-shaped end 18 of the base structure B.
Since the convoluted fluoresc~.nt lamp L and
integral circuit components are confined within a very
small space, care must be taken to prevent the operating
lamp unit 12 from overheating since this would cause the
lamp efficacy to decrease and could create a potential
safety ha~ard. These problems are avoided in accordance
with the invention by providing a plurality of vent aper-
tures 42 (see Figs. 3 and 4) that are~ spaced along the
bottom wall of the cup-shaped portion 1~ of the base
structure B, and by utilizing a protective cover C which
consists ~f a cylindrical sleeve having a tapered end 43
with a central opening 44~ which opening (in conjunction
with the vent apertures 42 in the base structure) permits
the free circulation of air through the operating lamp
unit 12 in chimney-like fashion. The resulting "convec-
tion cooling effect" dissipates heat generated by thefluorescent lamp L and ballast component 15 and ensures
that they do not become too hot.
In order to minimize light losses, the ballast
component 15 is desirably covered by a sheath 45 (shown in
Figs. 3 and 4) of suitable white or light-colored insulat-
ing material such as a heat-resistant tape or plastic. Of
course, a metal case can also be used as the light-
reflective sheath instead of the tape `or plastic, provid~
ing due care is taken to insulate the ballast from the
metal case. As will be noted in Fig. 4, the ballast
component 15 desirably comprises a so-called "finger" type
choke ballast that has an iron core 46 whîch is overwound
with insulated wire 47 and encased in the light-reflective
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sheath 45.
The cup-shaped support portion 18 of the base
structure B can be formed from suitable metal such as
aluminum, providing the conductors which connect the
circuit components to the lamp electrodes are properly
insulated to prevent short circuits. The screw^in base
member 20 is preferably of the "medium" screw type and can
be secured to the bottom wall of the cup-shaped support 18
- with suitable fasteners, or it can be formed as an inte-
gral part of the cup-shaped support 18 by stamping the
cup-shaped member and base shell from a single piece of
metal (or by molding it from suitable plastic).
The protective cover C can be made of glass,
heat-resistant plastic or other suitable transparent or
translucent material that will not absorb the light rays
generated by the fluorescent lamp L. If transparent
material is used, it may be made trans~lucent by a white
light~diffusing coating (or other means) to reduce glare
from the bright surface of the triple-U-bent lamp L and to
provide a more uniform and pleasing lighted appearance.
The starter component 17 is of the conventional
"glow lamp" type that is permanently wired in place.
However, it could be made in the form of a fuse-like
component and mounted within the base structure B in such
a manner that it may be readily removed and replaced as
necessary by a twist-lock action. The condenser 16 is of
the miniature wafer type and is connected in the circuit
in such a fashion that it eliminates or minimizes radio
interference during lamp starting.
ALTERNATI~E COMPACT LAMP UNIT EMBODIMENT
(FIGS. 5-7)
An alternative compact lamp unit 12a, shown in
Figs. 5-7, employs a ballast component that is "built
into" the base structure Ba and thus provides a lamp unit
which is slightly longer but smaller in diameter or width
dimension than the embodiment just described.
As illustrated in Figs. 5 and 6, the ballast
component 15a according to this embodiment is of truncated
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cylindrical shape rather than elongated slender configura-
tion and is located within a similarly shaped extension ~8
that protrudes from the bottom of the cup-shaped portion
18a of the base structure Ba and is joined to the threaded
base member 20a. The ballast 15a is again preferably of
the choke type and consists of an iron core (not shown)
and a wire winding 47a that are encased in a suitable
sheath or covering 45a of nonconductive material (see Fig.
6). The wall of the cylindrlcal extension 48 is spaced
from the ballast component 15a and is provided with a
series of laterally extending vent openings 49 which
permit air to circulate freely around the ballast compo-
nent and through the base structure Ba when the lamp unit
12a is energized and in use.
As will be noted in Fig. 6, the triple-U-bent
fluorescent lamp La is identical to that employed in the
previous embodiment except that the U-bent segments 29a,
30a, 31a have a smaller radius of curvature and thus
reduce the spacing between the tubular leg segments 24a,
26a, 27a, 28a. The condenser 16a and starter 17a are
connected by the insulated lead-in wires 38aS 37a to the
ballast component 15a and lamp electrodes 35a, 36a and the
condenser and starter components are disposed within the
cup-shaped end 18a of the base structure Ba (in the space
beneath the medial U-bend 31a alongside the sealed legs
24a, 26a of the envelope 14a as in the previous embodi-
ment). The protective cover Ca is modified and consists
of a cylindrical sleeve (of translucent or transparent
material) that is open at both ends and is seated in and
3 gripped by the circular cup-shaped portion 18a of the base
structure Ba~
As indicated in Figs. 5 and 7, the placement of
the ballast component 15a within the base structure Ba
increases the overall length h2 of the lamp unit 12a but
permits a "tighter bundling" of the tubular leg segments
of the convoluted envelope 14a with a resultant decrease
in the width dimension w2 of the lamp unit, compared to
the corresponding dimensions of lamp unit 12.
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As in the previous embodiment, heat generated by
the triple-U-bent fluorescen~ lamp La and the integral
circuit components is dissipated by convection cooling
produced by the air which circulates through the energized
unit through the vent openings 42a and 49 in the base
structure Ba and out o~ the open end of the tubular pro-
tective cover Ca.
ADDITIONAL ALTERNATIVE LAMP UNIT EMBODIMENT
' (~IG. 8)
From the standpoint of -the consumer, it would be
very advantageous financially to be able to remove and
replace only the convoluted fluorescent lamp component of
the lamp unit and retain the base structure, protective
cover and circuit components as permanent parts of the
lighting fixture in which the lamp unit is used. A lamp
unit 12b which provides this cost advantage is shown in
Fig. 8 and will now be described.
As will be noted, the fluorescent lamp Lb has
the same triple-U-bent type tubular envelope 14b as in the
previous embodiments except that the sealed ends of the
leg segments 24b and 26b are fitted with small plug-in
type base members 50, 52. These base members have pro-
truding contact elements such as rigid pins 51, 53 that
are adapted to be inserted into aligned receptacles of a
suitable socket member (not shown) located within the
cup-shaped portion 18b of the base structure Bb. The
resulting plug-in type electrical connection of the lamp
component Lb and the base structure Bb- permits the con-
sumer to simply remove the cover Cb and unplug and remove
the lamp component (when it becomes inoperable or has
reached the end of its useful life) and then plug in a new
lamp component. Hence, the lamp unit 12b can be readily
relamped by the user and the waste and added expense
associated with discarding the entire lamp unit each time
the fluorescent lamp "burns out" is avoided.
In order to rigidify the lamp envelope 14b and
permit it to be handled wi~hout breaking, the plug-in base
members 50 and 52 are desirably secured to a transverse
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panel member 54 of suitable nonconductive material. In
addition, this panel member can be coupled to the medial
U-bent segment 31b of the envelope by a suitable brace
means such as a wire strut 56 that has a hooked end 57
which is slipped over and grips the medial U-bent segment.
The panel member 54 is also desirably shaped to nestingly
engage the cup-shaped end 18b of the base structure Bb and
, seat against a part thereof in such a manner as to stabi-
lize the fluorescent lamp Lb in its upright assembled
position relative to the base structure.
While the sealed ends of the convoluted tubular
envelope 14b have been provided with pin-type base~mem-
bers, it will be appreciated by those ski~led in thè~ art
that other kinds of bases and electrical coupli`ng~; means
can be employed which will permit the fluorescent lamp Lb
to be easily removed from the lamp unit 12b~as a separate
part by the user and replaced by a n~w lamp compo~ent.
In contrast to the previous embodiments, the
starter and condenser components (not shown) are ~ired to
2~ the ballast component 15b and the plug-in socket ~eans
- (also not shown) so that they constitute permanent inte-
- gral parts of the base structure Bb. Alternatively, the
starter and condenser could be mounted on top of panel
member 54 and connected to the lamp lead-in wires in an
appropriate manner so that all three of these connected
components comprise a replaceable assembly that can be
unplugged from the lamp unit. Of course, if the starter
and condenser were connected to the lamp leads in the
proper fashion, then only two pin contacts rather than
four would be required.
~ s will also be noted in Fig. 8, the ballast
component 15b is housed within a cylindrical extension 48b
of the base structure Bb so that it`also constitutes a
permanent integral part of the base structure. Vent
openings 42b and 49b in the base structure Bb permit free
circulation of air around the ballast component 15b,
through the cylindrical jacket or cover Cb past the
triple-U-bent lamp Lb, and through the open end of the
;
.; . : ,
17 48,242
cover. The base structure Bb is terminated by a threaded
base member 20b having exposed contacts so that the lamp
unit 12b is once again of sin~le-ended construction and
adapted to be screwed into an incandescent-type lamp
socket.
ALTERNATIVE COVER EMBODIMENTS
(FIGS. 9-11)
_
The compact discharge lamp units of the present
invention can be fitted with various types of protective
jackets or covers in addition to those previously des-
cribed. For example, the light-transmitting cover can be
closed at one end by a dome that is provided with suitable
vent openings to permit the free passage of air. A cover
Cc having these features is illustrated in Fig. 9 and
consists of a light-transmitting sleeve of tubular or
cylindrical shape that is terminated by a dome 58 having a
plurality of circular apertures 59 that ~are distributed in
a predetermined spaced pattern.
A modified domed-end type protective cover Cd
that is specifically designed for a compact lamp unit
having an upstanding elongated ballast component disposed
in nestled relationship within the legs of the triple-U-
bent lamp is shown in Fig. 10. As will be noted, this
cover consists of a cylindrical sleeve that is also termi-
nated by a domed end 60 which 3 in addition to a pluralityof spaced apertures 61~ also has a central opening 62 that
communicates with a longitudinally-extending passageway 63
which is defined by a coaxially disposed tube 64 that is
joined to and merges with the domed end 60. The axial
passageway 63 is located to accommodate the elongated
ballast component of the lamp unit and is dimensioned to
fit between the U-bent sections of the triple-U-bent
envelope when the cover Cd is secured`to the base struc-
ture of the lamp unit. The passageway 63 is also slightly
larger than the ballast component and thus serves as a
"chimney" that enables air to circulate freely through the
lamp unit from the vent openings in the base structure,
around and along the ballast component and then through
18 48,24~
the central opening 62 in the domed end 60 of the cover
Cd. The U-bent sections of the convoluted envelope are
; disposed in the annular space between the c~axial tube 64
and cylindrical wall of the cover Cd and are thus exposed
to air which circulates through this space from the base
structure of the lamp unit and through the dome apertures
61.
Another form o~ domed cover Ce is shown in Fig.
ll and consists of a light-transmitting sleeve of tubular
o or cylindrical configuration having a domed en~ wall 65
that is provided with a plurality of spaced circum~eren-
tially-extending vent openings 66 of slot-like configura-
tion. The overlying portions of the cover Cd are flared
outwardly and form louvers 67 that serve as protective
shrouds or hoods for the vent openings.
SPECIFIC_EXAMPLES
A better appreciation of the compactness and
advantageous energy-conserving characteristics of the
fluorescent lamp units provided by the present invention
will be obtained from the following specific examples of
two prototype units that have been made and are presently
being tested.
A compact fluorescent lamp unit of the type
shown in Figs. 1-4 having a nested "finger" type choke
ballast and a medium screw-type base was made by bending a
tubular fluorescent lamp 20 inches (50.8 cms.) long and
0.69 inch (17.5 mm.) in outside diameter into triple-U-
bent configuration so that the o~7erall length of the
convoluted lamp was approximately 5-1/2 inches (14 cms.)
and its width approximately 2-l/4 inches (5 7 cms.). The
spacing between the medial U-bent section and sealed end
legs of the envelope was about 7/8 inch (22.2 mm.) and the
end legs were spaced about l/2 inch (12.7 mm.) apart. An
elongated "finger" choke ballast measuring about 3/4" x
3/4" x 4" (l9 mm. x l9 mm. x 101.6 mm) was inserted in
nestled relationship within the three U-bent sections of
the fluorescent lamp and connected to the lead wires and a
conventional type "glow-lamp" starter and wafer condenser
:,
q
19 ~o,242
used for standard preheat type fluorescent lamps.
The resulting subassembly was mounted on a
2-13/16 inch diameter (7.14 cms.~ support member of the
type shown in Figs. 1 and 3 having 1/4 inch (6.4 mm.) vent
apertures and a medium screw-type base. A protective
cover consisting of a frosted glass cylinder approximately
5-1/2 inches (14 cms.) long and 2-3/4 inches (7 cms.) in
diameter having a `central opening of 1-3/4 inches (4.44
cms.) was slipped over the convoluted fluorescent lamp and
seated in the cup-shaped support portion of the base
structure.
The completed fluorescent lamp unit had an
overall width dimension wl of 2-13/16 inches (7.14 cms.)
and an overall height hl of about 7 inches (17.8 cms.).
The triple-U-bent envelope was coated with "Cool White"
halophosphate type phosphor and the lamp unit, when oper-
ated at 120 volts input at a current of~345 milliamperes,
had an output of 1,~00 lumens and a system efficacy (that
is, the fluorescent lamp component in combination with the
choke ballast) of approximately 37 lumens per watt. The
total power comsumption of the lamp unit was approximately
27 watts (about 20 watts in the fluorescent lamp component
and about 7 watts in the ballast).
A second prototype fluorescent lamp unit made in
accordance with the Figs. 5-7 embodiment contained a
triple-U-bent fluorescent lamp which was formed from an
envelope 20 mm. in diameter and 43.1 cms. long. The
convoluted lamp component had an overall length of 13
cms., a width of 5.1 cms. and the legs of each of the
U-bent sections were spaced 11 mm. apart. The lamp was
mounted on a base structure having a cylindrical extension
that housed a cylindrical choke ballast, the "glow-lamp"
starter and the wafer condenser. The base structure had a
circular cup -shaped end approximately 2-7/8 inches (7.3
cms.) in diameter and a cylindrical open-ended cover of
frosted glass having a diameter of about 2-3/4 inches (7
cms.) and an overall length of 5-1/2 inches (14 cms.) was
secured to the base structure. The resulting lamp unit
.
48,242
had an overall width dimension w2 of approximately 2-7/8
inches (7.3 cms.) and an overall height dimension h2 f
approximately 8-1/8 inches (20.6 cms.). When the lamp
unit was operated at 120 volts input and 345 ma, it had a
light output of approximately 960 lumens and a system
efficacy of 40 lumens per watt.
While life tests on triple-U-bent fluorescent
lamps of the type employed in the compact lamp units of
the present invention have not been completed, the lamps
should have useful lives in the order of 9,000 hours or so
since, when mass-produced, they would be made with stan~
dard stem and electrode assemblies and utilize the well-
known phosphor coating techniques and other technology
used to manufacture conventional fluorescent lamps of
equivalent size (15 to 20 watt rating) that have nominal
life ratings of such magnitude.
In contrast, a standard 75 watt Al9 type incan-
descent lamp produces about 1,210 lumens at an efficacy of
about 16 lumens per watt and has an average life (pub-
lished) of only 850 hours.
As will be apparent to those skilled in the art,the compact fluorescent lamp units of the present inven-
tion can employ triple-U-bent fluorescent lamps made from
glass tubing of various diameters and lengths to provide
lamp units having higher or lower wattage ratings and
light outputs. The starting and/or operating circuits can
also be made in the form of solid-state modules or com
ponents that are "built into" the base structure or
mounted between the legs of the U-bent sections of the
envelope to provide a new family of compact low-pressure
discharge lamp units that can be advantageously used as
cost-saving and energy-conserving replacements for incan-
descent-type lamps now employed for general lighting
applications in homes and offices. The use of solid-state
circuit means would be particularly advantageous in fabri-
cating screw-in type lamp units having light output~ of
2,000 lumens or so since the miniaturized circuitry would
still make it possible to keep the overall dimensions of
. .
21 48,242
such high-output lamp units within the limits required to
- permit the units to fit into and be used in table lamps
and similar lighting fixtures designed for incandescent
type lamps.
Of course, if the ballast and other circuit com-
ponents were physically separated from the fluorescent
lamp and made part of a specially-designed lighting fixture
(for example, if they were housed within the base of a
table lamp or floor lamp), then step-up transformers,
-10 high-frequency converters and similar en~rgizing means can
be used to increase the efficacy of the system and make
` the lamp units per se even more compact and economical.
In addition, the ballast component can be physically
separated from both the discharge lamp unit and the light-
ing fixture by making the ballast a "pass-through" type
that would be connected to and constitute a part of the
power cord. Alternatively, such a "pass-through" ballast
component could be made in the form of a unit that plugs
directly into the wall socket and is connected to the
lighting fixture by a power cord.
..
