Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
lX81766
METHOD AND APPARATUS FOR POSITION ORIENTATION
OF A METAL HALIDE LAMP BASE ASSEMBLY
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TECHNICAL FIELD
The present invention relates in general to metal
halide lamps and in particular to a method and apparatus
for position orienting a metal halide lamp base with
respect to a curved arc tube.
BACKGROUND
Metal halide lamps that are made with curved or
arched arc tubes must be operated horizontally with the
curve of the arc tube in the upward or arch uppermost
15 pos~tion (see U.S. Patent No. 3,858,078). To accomplish
thls, thè base and socket must provide a means of
interlocking such that when the lamp is screwed into the
- socket firmly, the arc tube curve will be upward.
Presently, the socket used has a notch and the base has
a pln added to it so that when the lamp is screwed into
the socket, it will stop in a predetermined position.
This is in contrast to the usual screw type base that is
used with prior art commercial metal halide lamps; a
screw type base ls not a po~itioning base and can be
used in prior art lamps sin~e the arc tubes thereof
straight cylinders.
It is an object of this invention to provide a
method and an apparatus for position orienting a base
with respect to a curved arc tube.
In accordance with one aspect of this invention,
there is provided a method for position orienting a base
assembly with respect to a curved arc tube of a high
intensity discharge lamp, the base assembly including a
base shell having an eyelet and a locator structure
attached thereto. The method comprises the steps of
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providing within the discharge lamp an arc tube support
structure coplanar with the arc tube and providing means
for welding the locator structure to the base shell, the
welding means capable of separately receiving and
supporting the lamp and the locator structure. The
method further includes disposing the locator within the
welding means and psoitioning the lamp within the
welding means such that the base shell and the locator
are in operative contact before welding. Next a light
source is provided proximate to the welding means and
the light beam of the light source is aligned
perpendicular to both the longitudinal axis of the lamp
and to the plane formed by the arc tube and the locator
structure. Furthermore, a screen is provided opposite
the lamp such that a shadow image of the arc tube
support structure is formed thereon when the light beam
passes throught the center of the neck of the lamp and
impinges on the screen. Flnally, the lamp is rotated
radially within the welding means until the plane formed
by the arc tube and the support structure is
perpendicular to the arc tube - locator plane:
Thereupon the welding means is activated to weld the
locator structure to the base shell, thereby forming a
base assembly that is position oriented with the curved
arc tube.
In accordance with another aspect of this invention
there is provided a position oriented high intensity
discharge lamp comprising a light transmissive outer
envelope and a curved arc tube disposed within the
envelope and supported by an arc tube support structure
that is coplanar with the arc tube. The lamp further
includes a base assembly attached to the outer envelope,
the base assembly having a base eyelet and a locator
structure affixed externally thereto, the locator
disposed at a predetermined distance from the base eyelet.
In accordance with yet another aspect of this
invention, there is provided an apparatus for attaching
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a tab-type structure to the base of a high inte~sity
discharge lamp. The apparatus comprises a resistance
welder and a welding fixture attached to the welder
including a frame, a bottom electrode disposed within
the frame having an apertured surface, and means for
guiding the lamp within the apparatus in contact with
the frame. The apparatus further includes a back stop
structure having a sur~ace positioned proximate to the
guide means for minimizing the lamp movement within the
apparatus and a retractable top electrode positioned
above and spaced from the bottom elecrode.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 illustrates an example of a typical curve
arc tube metal halide lamp base;
Flgure 2 illustrates a cross section of a known
socket for a high intensity discharge lamp;
Figure 3 illustrates the top or dome end view when
looking down onto a curved arc tube metal halide lamp;
Figures 4A through 4C illustrate an actual metal
halide lamp containing a curved arc tube therein, a high
intensity discharge lamp having the improved locator
structure attached to the base and enlarged view of the
improved locator structure, respectively;
Figures 5A and 5B lllustrate slde and front vlews of
the welding apparatus for attaching the locator
structure onto the lamp base;
Flgure 6 illustrates how the high intensity
discharge lamp is posltioned ln the welding fixture of
flgure 5; and
Figures 7A and 7B illustrate the lamp and the
fixture position with respect to a light source and
screen used for aligning the lamp base with the arc tube.
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Re~erring now to Figures 1 and 2, which will aid in
clearly illustrating any problems associated with the
prior art lamp bases, figure 1 illustrates a typical
lamp base 10 comprised of a base shell 12, a base eyelet
14 and a base pin 16. Figure 1 also illustrates a
headed brass pin 16 which is a~fixed into and protrudes
from base shell 12 in order to position the curved arc
tube of a metal halide lamp. Figure 2 illustrates a
cross section of a typical socket 20 made of a porcelain
casing 22 that has been partially cut away such that
notch 24 can be seen. To make the pin and notch
arrangement workable, a given dimension of X, X being
about one inch with a positive tolerance of 1/32 of an
inch was established between base eyelet 14 and pin 16,
ln Figure 1. Notch 24 (illustrated in Figure 2) in the
socket shell 26 is located such that when base pin 16 is
wlthln the dimenslons stated, eyelet 14 on base shell 12
will make contact with tab 28 in the socket. The
tolerance of plus 1/32 of an inch translates into
rotational tolerance of about 45 degrees of rotation or
about 5t8 of an inch distance along the crest of the
thread on which the pin is located
The present method of pinning and attaching the base
to the lamp is as follows; a hole is drilled in base
shell 12 on the crest of the thread to meet the
dlmenslon stated with resPect to Figure 1. A headed
brass pln 16 ls then inserted into the hole with the
head on the inslde of base shell 12 and se-urely
soldered in place. Since the soldering discolors the
brass, the use of a nickel base is necessary for good
cosmetics. During the lamp sealing process, four
dimples are molded into the seal to permit a threaded
inner shell having tabs with corresponding dimples to be
snapped in place. Once in place, base shell 12 is
securel~ screwed onto the inner shell and then is staked
or Pierced in three places to lock it to the inner
shell.
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When sealing lamp~ with a curved arc tube, the tip
on the arc tube is located with respect to one Q~ the
dimples in the mold. In the basing process, the inner
shell is selectively snapped into place such that the
thread location on the inner shell corresponds to the
dimple orientation accomplished during the sealing
process. When the base is screwed onto the inner shell,
the pin should be approximately 90 degrees counterclock-
wise fro.,l the tip on the curved portion of the arc tube
when viewed from the dome end of the metal halide lamp.
Figure 3 illustrates a metal halide discharge lamp 30
when viewed from the top dome end looking down onto the
lamp. Lamp 30 has an outer envelope 32, a curved arc
Tube 34, arc tube pressed end 36, and arc tube tip 38, a
base shell 40 and a locating pin 42 slmilar to Figure
1. Figure 3 al~o illustrates a plane of the arc tube
and support structure which runs along the line B-B'. A
90 degree angle ls marked between the plane of the arc
tube B-B' and the plane created by the arc tube and the
locatlng pin marked C-C'.
The posltion orientation or locating arrangement in
the past has not been very accurate, since the base has
normally been manually screwed onto the inner shell
until snug then the pin location i~ checked wlth respect
to plane B-B' to see if the angle between them is 90
degrees + 5 degrees. If the angle is not within this
range, the base must be loosened or tightened to meet
the requirement. This action allows for a certain
amount of movement to meet the angular requirement,
however lf the base is backed off too much from the snug
position, the base will be loo~e after staking. If the
base is over torqued, the lamp seal will crack. In either
case, the lamp is rejected. The problems associated
wlth the present pin locating methods are as follows:
possible rejections mav occur due to the loose base or
cracked seal and over torquing can cause severe
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field and life problems. The present method does not lend
itself well to an efficient assembly line operation
and predrilling of bases and soldering pins on are time
consuming and expensive. Since soldering discolors a
brass base, nickel plated bases must be used for good
cosmetics, therefore nickel plating is an added expense.
Since production operations are constantly changing,
such as utilizing a threaded glass seal in place of dimples
and an inner shell for attaching the base, the present
method as described is not adaptable for use with
a threaded mold lamp seal. Therefore, a need exsists
for a method of position orienting a metal halide lamp
base assembly with respect to the curved arc tube.
Figures 1, 2 and 3, were used to help describe some
of the problems associated with the prior art methods of
positioning or position orienting a base with respect to
a curved arc tube. Reference will be made throughout the
specification to Flgures l and 3 in order to describe
the improved method and apparatus for position orienting
a base with respect to a curved arc tube. With respect
to Figures 4A-4C, Figure 4A illustrates a known metal
halide lamp 30 in a horizontal position having a curved
arc tube. Lamp 30 in Figure 4A indludes an outer
envelope 32, an arc tube 34, an arc tube pressed end 36,
an arc tube tip 38, a base shell 40 and an arc tube
support structure 44. Figure 4B partially illustrates
an improved metal halide lamp 50 and lamp neck 53 having
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a base asseubly Sl which include6 a base shell 52 and a
locator structure 54 Pigure 4C illustrates an enlarged
viev locator 6tructure 54 and surface 56 whic~ vill be
attac~ed to base s~ell 52 upon for~ing t~e ba~e as~e~bly
Sl illu6trated in ~igure ~B
According t~ one o~bodi~ent of tbe pre~ent
inventio~, a ethod for po6ition orienting a base
a~oubly vith rQcpect to a cur~ed arc tube of a ~igh
int-~-ity discha~go laup vill be de w ribed The la~p of
Pigur- 4A i6 alignod a~ ~ievod in Pigure 3 so that tbe
plan- or the arc tube B-B' as ~hovn in Pigure 3 is
aligu d vitb the ~tart vith the fir~t thread on the
threaded uold of the glass, this align~ent being
acco~pli~hed during laup cealing The laup6 6ealing,
exhauct and basing are th~n coopleted, including the
ba~e w lderinq operation A nevly dosignod tab-type
locator 5~ ~hovn in Piguro 4C is then placed iD a
~-ldiDg apparatus 60 w~ich is illustrat-d in ~igures 5A
and 5B, W-lding apparatus 60 illustratod in ~igures SA
and 5B pro~i~es a eans ror wolding locator structure 54
to ba~e ~hell 5~ Th- volding apparatu6 is capable of
s-parately recoi~ing and supporting la~p S0 and locator
structure 54 As illu~trated iD Pigure ~C locator
~tructure 54 is L-shap-d in toru
Pigur-s SA and SB illustrato apparatus 60 tor
attaching a tab-type structure to tho ba~e Or a hig~
int-Daity discharge la~p Apparatus 60 comprisos a
rs~i~taAce v-ldor 61 and velding fixture 62, attac~od to
velder 61, that include~ a rra~o 63, a botto~ olectrode
64 di~po~ed within fra~e 63, having an apertured ~urface
66, and tvo guide pin~ 68 to guide a laup vithin fixture
62 poritioned on either ~ide of botto~ electrode 64. A
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bac~ stop 70 i8 positioned proxi-ate to guiae pins 68
and ~ retractable top electrode 72 i~ pos~tioned above
and spaced fro~ botto~ electrode 64 Aperture 66 of
botto~ electrode 64 6upport~ locaeor structure 54 that
i8 to be attac~ed to the la~p ba6e
The locator ~tructure 54 i6 next placed in aperture
66 of bottou oloctrode 64 of apparatu6 60 La-p S0 i~
tb-~ placod betveen guide pin~ 68 witb tbe base eyelet
being placed in operati~e contact ~ith bac~ 6top
~tructure 70 rixture 62 i~ ~esigned ~UCD t~at tne
cro~t o~ tho throad of ~a~e ~hell 52 i6 alvay6
po~itio~od o~or botto~ ctrode 64 and aperture 66
With tho baro oyolet clo~e to bac~ ~top 70 the plane of
t~- a~c tube B-B', a~ aligned in Pigure 3 i~ near to
tbo corr-ct location The tolerance of plu~ 1~32 of an
inch ~,04 inch-~) tran~lates into a rotational tole~ance
of about 45 d-gr--~ ot rotatioD or about 5/~ of an iDCh
aloDg th- cr-~t of th- thread oo ~hich tab locator
~tructur- 54 i~ to b- located, With tbe alignaent
~lluat~at-d iD Pigur- 3, the proper tab locatioD vill
alvayr rall vithin that 5/8 of an incb on the threaded
cr-~t The tab or locator ~tructure i~ nov dispo~ed
~ithin ~-lding apparatu~ 60 and la~p 50 is positio~ed
vithin volding apparatu~ 60 6ucb tbat ba~e 6hell 52 and
locator 5~ ar- in op-rati~o contact bororo volaiDg (~oe
r~gu~- 6 ) .
~ -r-rring to pi9urQ 6, Pigure 6 illu~trates la~p 50
po~it~on-d vithin wolding ~ixturo 62 aDd illustrato~
lavp upport brac~ot 74 vhich ~upport~ la~p 50, that i~
~pac- rro~ l-ctrode 64 Pigure 6 al~o illu~trate~ that
laup 50 har a loDgitudiDal axi~ 75 vhich vill help iD
alig~i~g locator structure 54 vith the arc tube of la~p
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50 ~igure 6 al~o illu~trates that top electrode 72 i~
retractable and will co~e down on base ~hell 52 to veld
locator 54 located witbin botto~ electrode 64, to base
ehell 52 vhen tbe lamp has beeD properly aligned
S Referring AOV to Figure~ 7A and 7B, ~igure 7A
illu~trates la~p 50 po~itioned vithin fixture 62 V~tD
re~pect to a ligbt source 76 and a target or screeD 78
tbat i~ usea for properly aligning the la~p base and tbe
locator ~tructure while Pigure 7B illustrates tbe ~iev
through ~ection A-A' of Pigure 7A In particular~ light
~ourc- 76 i~ located proxi~ate to fixture 62 and a lig~t
b-a~ 77 e~itted rro~ eource 76 i~ aligned to be
porpendicular to botb longitudinal axis 75 (eee Pigure
7B) Or la~p 50 and to tbe plane ro~ed by tbe arc tube
~nd the locator ~tructuro which ie identified as 80 in
Pigur- 7A Light ~ource 76 in Piqure 7A is positioned
oppo~it~ p 50 euch that light bea~ 77 pa~se~ tbrough
the c-nt-r Or tbe ncc~ 53 o~ the la~p and i~pingee on
~¢r--n 78, Light b~a~ 77 ie aleo adjusted to be
~-rp-ndicular to th- plane ror~-d by tbe lower arc tube
~u~port ~tructur~ 44, as illuetrated in Pigure 7B, that
i~ ~ttacb-~ to arc tube 34 (~ee Pigure 7B)
ID this particular e~bodi~eot, ligbt bea~ 77
~hinniDg througb o-c~ 53 o~ la-p 50 vill sbov 2 ~hadov
lin-~ rrou lo~er eupport etructure 44 onto 6creen 78
rrO~ tb~ tvo lege Or lov-r ~upport ~4 La~p 50 i~ t~en
rotated radially eith-r cloc~viJe or countercloc~vise
until the tvo lege or ~upport 44 register as one ~bado~
line on w r-eo 78, At tbi~ point, tbe plane ror~ed by
th- arc tub- and tbe ~upport 6tructure i~ perpendicular
to the arc tube locator plan- 80 Tab or locator
etructure 54 in botto~ electrode 64 i~ nov about 9o
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degrees countereloc~ e ro~ arc tube tip 38 ~ ~ho~n
in Pigure 3 Res~6tance ~elder 61 is nov act~vated to
re~i~tance ~eld the tab or locator structure 54 to ba6e
~hell 52 thereby for~ing a ba6e asce~bly that iE
po6~tion oriented with re~pect to curved arc tube 3~
Pigur- 4B ~ho~ locator ctructure 54 velded to the bace
of the la~p
Therefore t~rough the u~e of the aforedeccribed
~thod, an inprovod pocition oriented h~gh intensity
diccharge la-p ha~ recult-d ther~fro Such an i~proved
pocition ori-nt-d di w harge lanp i~ partially
illuftrated rrO~ the la~p i~ ~igure ~A and the base
afce-bly Or rigure 4B The i~pro~ed ldmp co~peisec ~06t
Or tho lo~ent~ o~ the la~p illu~trated in ~igure 4A
~ith ba~o asce-bly 51 of Pigure 4B The locator
ctructure 54 or ba~e a~co~bly 51 ic dicpo~ed at a
pr-d-t-r~ined dictance fro- the ba~e yelet ~ Locator
ctructu~e- 54 al~o hac a predeter~ined rotational
tol-rance radially along ba~e chell 52 The
~red-ter~lD-d ai~taDc- i~ vithin a raDge of about one
inch to about 1 05 inchec and the rotational tolerance
ic about 45 d-gree~ of rotation along the cre~t of t~e
thr-ad of ba~e chell 52
Sh- advantagec o~ u~ing 6UCh an i~proved ~etal
bal~- laup include~ th- ab~ence or ce3ection~ due to
loo~e bac-~ or crac~ed ceal~ The ba~e dooc not have
anr aperture~ (aue to prior art prearilling to include
t~e pi~ rrOu the previouc la~p) and ~elding of tbe
locator ~tructure onto the ba6e ~ill not di6color the
brac- bace therefore nic~el plating of the base is an
unn-ce~cary ~anufacturing ctep ~bich al~o increa~es the
exp-nce of the la-p
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~ bile tbere ba~e been 6bown and de6cribed ~at are
at present con~idered t~e preferred e~bodi~ent6 of tbe
invention, it ~ill be obvious to those s~illed in t~e
art t~at variou~ changes and ~odifications ~ay be ~ade
t~erein ~ithout departiDg fro~ the scope of t~e
in~eDtion as aefined by t~e appended Clain6.
