Note: Descriptions are shown in the official language in which they were submitted.
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P~N 9917 l 1.7.1981.
Electric incandescent lamp.
The inventi.on relates to an electric incandes-
cent lamp having a glass lamp envelope which comprises a
pinch, in which lamp envelope a filament is accommodated,
connected to current supply conductors which emanate in
a vacuum-tight manner through the pinch and which are con-
nected to the contacts of a lamp cap which consists for
the greater part of an electrically-insulating body, the
pinch of the lamp envelope extending in a recess in the
insulating body and being secured therein by means of a
cement. Such a lamp in which the insulating member is a
ceramic body is known ~rom Netherlands Patent Application
6717374 and may be used as a projection lamp, a studio
lamp, or a theater lamp.
In all cases in which a lamp is used in an opti-
lS cal system, the filament should be aligned with respect
to the lamp cap so that, when the lamp is placed in a
lamp holder of an optical system, the filament occupies
a previously determined position in said~system.
. : Lamps for the above-mentioned application often
:.~ 20 consume a high power and emit light o~ a high colour
temperature. The resulting high pinch temperatures neces-
. : sitate the use of a lamp cap having an insulating member
of ceramic or of a synthetic resin which can withstand
; hi.gh temperatures, up to approximately 4OO C, and neces-
sitate the use of a cement for the connection o~ the lamp
cap to the lamp envelope. ~ ~
~ The curing of cement requires;a comparatively
:: long time. In that time, the lamp envelope and~the lamp
~: : cap should remain fixed and aligned so as t~o prevent any
~ 30 displacement of the fllament relative~to:the lamp cap.
~ This involves a prolonged occupation of the alignment ap-
~ paratus and increases the cost of the lamp.
It is the object of the invention to provide a
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PHN 9917 2 1.7.1981.
lamp construction which enables the cement which connects
the lamp cap to the lamp envelope to be cured outside an
alignment apparatus.
According to the invention this object is achiev-
ed in a lamp of -the kind mentioned in the opening para-
graph in that at least one projection which determines the
depth to which the pinch extends into the recess in the
insulating member of the lamp cap is present on the sur-
face of the pinch.
In manufacturing lamps, the filament can be
positioned in the lamp envelope with great accuracy at a
given distance from a reference on the pinch. By construct-
ing the reference on the pinch as one or more projections
on the surface of the pinch and proportioning said pro-
jections so that when lamp cap and lamp envelope are unit-
ed the projection(s) cannot penetrate into the recess or
cannot penetrate into the recess in the insulating member
of the lamp cap further than a previously determined amount,
the distance from the filament to the lamp cap is fixed
in the lamp according to the invention. This distance, the
so-called light centre length, is the most important para-
~ meter of the position of the filament.
,r`, The construction of the lamp according to the
invention makes it possible to cure the cement which se-
cures the lamp envelope and the lamp cap together without
an alignment apparatus being kept occupied during the
curing period. In lamps in which the centre of gravity of
the lamp envelope is situated near the lamp cap and a
stable support of the lamp envelope by the projections on
the pinch surface is ensured, it is even not necessary
to use mechanical auxiliary means 9 such as a lamp or a
-- jig, to fix the lamp envelope relative to the lamp cap
during curing~
In an embodiment of the lamp according to the
invention, a projection is present on the pinch surface
on each of the two oppositely-located wider side faces
- of the pinch. In a modified embodiment, two or more pro-
jections are present on each of these two side faces. In
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P~N 9917 3 1.7 1981.
this modified embodiment the lamp envelope during the ma-
nufacture of the lamp has a particularly stable position
with respect to the lamp cap.
The projections on the pinch surface may bear
5 against the insulatlng rnember itself la-terally of the
recess therein. ~nother possibility is that the recess
in the insulating body is covered for the greater part
by means of a glass, ceramic, synthetic resin or metal
disc which has an aperture through which the pinch of the
lamp envelope can only be passed up to the projection(s).
~n this embodirr~ent commercially-available lamp caps may
be used which are destined to be united with a lamp en-
velope in a conventional manner so as to form a finished
lamp.
The lamp according to the invention has the ad-
vantage that the afore-mentioned disc or the boundary of
the recess in the insulating member forms a supporting
surface for the cement which joins the lamp envelope to
the lamp cap. In conventional lamps the recess in the lamp
cap, after the pinch of the lamp envelope has been placed
therein, is filled with sand so as to form a supporting
surface for the cement and to prevent tha-t a lot of cemen-t
is used~ In the lamp according to -the invention the use
of sand is superfluous, as will become apparent herein-
after.
The lamp according to the invention may have alamp cap for use in an Edison or bayonet lamp holder, or
in a lamp holder of a different shape, for example with
one or more sockets. Due to -the high colour temperature,
the high yield and to the luminous efficiency of halog0n
incandescent lamps which remains the same during the life-
time, the lamp according to the invention may comprise
halogen in addition to inert gas, and may hence have a
lamp envelope of a type of glass having a high silicon
dioxide content, for example, of 95% by weight or more,
for example, quartz glass.
Embodiments of the lamp according to the invent-
ion are shown in the drawing. In the drawing
PHN 9917 4 1.7.1981.
Figure 1 and Figure 2 are a front elevation and
a side elevation, respectively, of a first embodiment,
Figure 1 being a par-tial sectional view of the lamp cap;
Figure 2a is a plan view of a component of that
embodiment;
Figure 3 is a f`ront elevation of a second embo-
diment;
~ igure 4 is a sect:ional view taken on the line
I~-IV of Figure 3; and
Figure 5 is a analogous sectional view of a
third embodiment.
In Figures 1 and 2 the lamp envelope l has a
pinch 2 and a filament 3 which is connec-ted to current
supply conductors 4 and 5 which emanate in a vacuum-tight
manner through the pinch 2 and are connected -there to the
contacts 8 and 9 of a lamp cap 6 consisting for the great-
er part of a ceramic body 7 of steatite. The contact 8 is
previously secured to the body 7 by means of cement 16.
The ceramic body has a recess 10 in which the pinch 2 of
the lamp envelope 1 extends. At its surface, on the wider
side faces 15, the pinch 2 has two pairs of projections
12 which determine the depth to which the pinch 2 extends
in the recess 10 of the ceramic body 7. In this embodiment
a metal disc 13 is provided which bears on an edge 14.
The projections 12 bear on the disc 13. The lamp envelope
1 is connected to the lamp cap 6 by means of cement 11.
Upon assembling the lamp, the stability of the lamp enve-
lope 1 in the lamp cap 6 is still increased in that the
current conductor 4 extends through the bottom of the
lamp cap 6 at the area where the contact 9 is to be pro-
duced. The disc 13 substantially covers the recess 10 so
that a supporting surface is presented for the cement mass
11 which is soft when being provided, and sagging away
of said mass into the recess 10 is prevented. The aperture
17 in the disc 13 (Figure 2a) only allows the pinch 2 to
be passed therethrough only up to the projections 13.
The reference numerals in Figure 3 and Figure 4
are 20 higher than those for corresponding components of
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PHN 9917 5 1.7.1gg1~
the lamp of Figure 1 and Figure 2. In these Figures, the
contacts of the lamp cap 26 are plug pins 28 and 29. The
recess 30 in the ceramic body 27 is proportioned so that
the pinch 22 fi-ts therein with a small amount of play. The
projections 32 on the surface of the pinch 22, however,
bear on the edge 34. In this embodiment the projections
32 are ribs which each extend over the whole width of the
relevant wider face 35 of the pinch 22 on which they are
present. The lamp shown is a 220 V 1,000 W theater lamp
having during operation a pinch temperature of 400 C and
a colour temperature of 3,000 K.
In Figure 5 the pinch 42 has a projection 52 on
only one wider side face 55. The remaining reference nume-
rals are 20 higher than those of corresponding parts in
Figure 4.
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