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Патент USA US2405286

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Aug. 6, 1946.
I 2,405,286
Filed Aug. 25, 1944
/,’/ /Q
Patented Aug. 6, 1946
Harry K. Bourne, Rugby, England, assignor to‘
General Electric Company, a corporation of
New York
Application August 25, 1944, Serial No. 551,184
In Great Britain January 2, 1943
6 Claims. (01. 315-118)
~ This invention relates to electric discharge A
lamps generally, and more particularly to equip
ment for and methods of operating such lamps.
It is frequently desired to reduce periodically
the light output from high pressure mercury
vapor lamps of the compact source type while
axially from the rear of the re?ector, which may
be of‘ parabolic shape,’ and the lamp is held in
a carriage slidable within the heat conserving
jacket, a cap being arranged on the carriage to
co-operate with the aperture in the re?ector
leading to the jacket. Thus when" the lamp is
retracted into the jacket, the cap covers the aper
enabling maximum light output to be imme
diately available. In order that these conditions
ture and completely prevents light emission,
may apply, it is essential that, during the periods
while at the same time completing-the enclosure
of‘reduced light output, i. e. of reduced power 10 of the lamp in the jacket- When the lamp is
input, the discharge in the lamp should'be main
ejected from the jacket it moves into a position
tained or “simmered.” To do this, it is necessary
to provide means for avoiding loss of heat from
in which the source of light is located at the
focus of the re?ector, the cap moving with the
the envelope or for supplementing the'heating
lamp and serving to preventthe emissionof
of the envelope to avoid too great a reduction of 15 direct rays from the lamp. . , r
the vapor pressure within the envelope.
An object of the present invention is to provide
a simple means for enabling a lamp of the kind
set forth to beoperated under simmering con
‘ To enable the invention to‘ be ‘more readily
understood reference is now directed to the ac
companying drawing which shows somewhat
diagrammatically and in section an arrangement
according to the invention.
The invention consists in providing a heat con
serving jacket between which and the lamp rela
tive movement is effected during the change-over
from vmaximum light output to simmering con
ditions, the. jacket enclosing the lamp and shield
Referring to the drawing the discharge lamp l
is mounted in a suitable holder 2 forming part
of a carriage movable with relation to a heat
conserving jacket 3 which projects axially from
The jacket 3 is pro
ing it both thermally and optically during the
vided with suitable lagging 5.
time that it is operated under simmering con
The jacket 3 is closed at its right-hand end by
a ?xed plug 6 having a central aperture in which
The heat conserving jacket thus serves, in ad
slides tube 1 forming part of the carriage and
dition, as an optical shutter, and is arranged 30 containing the leads 8 which convey operating
to surround the lamp and substantially com-'
potential to the lamp I from a source of poten
pletely enclose it during simmering conditions.
tial H, II through an inductance (choke coil) 12.
‘When moved relative to the lamp to permit max
. In the drawing the carriage is shown in the
imum light emission therefrom, this movement
position in which the lamp is ejected from the
takes place simultaneously with the operation 2.3 .or heat conserving jacket 3 into a position in which
of switching means for eifecting the removal of
the light source is located, preferably at the focus
series resistance or inductance from the lamp
of the re?ector 4 which may be of parabolic
circuit, whereby to increase the operating cur
shape. The position of the carriage is limited
rent through the lamp and enable the increased
by an adjustable stop 9 ?xed to the tube 1 which
light output to be available. When the relative 4.0 abuts against the plug 5. The carriage is also
movement of lamp and jacket is reversed, the
provided with a cap 09 which in the retracted
resistance or inductance is re-inserted in the lamp circuit.
' the rear of a re?ector 4.
position covers the otherwise open end of the
heat conserving jacket 3 and limits the extent
In one convenient embodiment, the heat con
of movement of the carriage in the retracted
serving jacket is constituted as part of a re
‘ position.
In the position indicated the cap I!)
?ector utilized for forming into a beam the light
also serves to prevent the emission of direct rays
emitted from the lamp. Then, during the periods
from the lamp I.
when the lamp is to be operated under simmering
Switching means are provided whereby in the
conditions and no light emission is desired, the
ejected position illustrated the power input to
lamp is retracted into the jacket; whilst when 50 the lamp is increased, while in the retracted po
light emission is desired, the lamp is ejected
sition the power input is diminished causing the
from the jacket into a position within the re
lamp to simmer. This may be effected by in
?ector at which the source of light is situated
serting into the circuit With the lamp additional
at the focal point of the reflector. In one ar
resistance or inductance I3. The added
rangement the heat conserving jacket projects
inductance or resistance may be inserted auto
matically by providing contacts carried by the
which the carriage is provided with a cap which,
in the retracted position of the carriage, covers
the otherwise open end of the jacket and com
pletes the optical and thermal shielding of the
tube 1 to effect the desired change of circuit con
nections. In the drawing, I have shown a ?xed
contact [4 and a movable contact l5 on the tube
‘I. In the ejected position, the contacts l4, [5 are
3. The invention as set forth in claim 1, in
closed to shunt the added inductance 13;. Retrac
which a re?ector is provided and in which the
tion of the tube 1 opens the contacts to insert the
carriage is provided with a cap which, in the re
inductance l3 in series with inductance l2. The
tracted position of the carriage, covers the other
are between the electrodes is satisfactorily main
tained under simmering conditions by the pro-‘ 10 wise open end of the jacket and completes the
optical and thermal shielding of the lamp, and
vision of the heat conserving jacket which pre-Y
in which the jacket projects axially from the rear
vents cooling of the lamp and maintains the
of said re?ector which is adapted to direct the
mercury vapor pressure within the :envelope
light from the lampwhen ejected from the jacket,
the cap preventing the emission of direct rays
If desired; the retraction of the lamp into the.
from the lamp in the ejected position and cov
heat conserving jacket may be effected electro-g
ering the aperture in the re?ector when the car
magnetically by making the carriage form the
riage is retracted into the jacket.
armature of an electromagnet energized by suit
4. The combination of a high pressure mercury
able switching means operated from a point re
mote from the lamp. This switching means may 20 vapor electric discharge lamp of the compact
then be arranged simultaneously to insert the ad
ditional series inductance or resistance simul
taneously‘ with the retraction of the lamp car
riageinto the jacket.
Preferably the lamp is constructed in the man
ner disclosed in the British Patent No. 550,581
since the construction enables all the necessary
supply conductors for the lamp to be connected
thereto at the end of the lamp which is at all
times within the jacket.
The arrangement shown may be utilized as a
means for providing an intermittent beam of
light for signalling purposes.
source type, supporting and positioning structure
comprising a fitting embodying a, heat conserving
jacket and a carriage retractable thereinto and
serving to support and selectively position the
lamp in either a substantially ejected light emit
ting position or in a position substantially en
closed by said jacket, and means actuated by said
carriage for connecting ahigh power source to
said lamp when in its ejected position and a
lower power source to said lamp when in its
retracted position.
5. The method of operating a high pressure
metal vapor electric discharge device which com
What I claim as new and. desire to secure by
prises alternately applying relatively high and
Letters Patent of the United States is:
I. In combination, a high pressure mercury
low power across the terminals thereof, and en
closing the device. in a thermal insulating jacket
only during the periods of operation at loW power.
(-7. In combination, a high pressure mercury va
porting and positioning ?tting comprising a heat
por lamp of a compact source type, a supporting
conservingv jacket, a circuit for supplying power
to said lamp, a carriage for supporting the lamp - and positioning structure for said lamp compris
ing a heat conserving jacket, a carriage for sup
and movable with relation to- the jacket so that
porting said lamp and movable with relation to
when the carriage is retracted into the jacket
the jacket to eject said lamp from the jacket‘ or
the lampv is thermally and optically shielded, and
retract it thereinto so that when retracted into
means simultaneously operated by the movement
the jacket the lamp is thermally and optically
of the carriage for reducing the power input to
shielded thereby, a source of high power, a source
the lamp when the carriage» is retracted into the
of low power, and means responsive to the posi
jacket, to an extent such that the lamp is oper
tion of said carriage for selectively connecting
ated under simmering conditions when shielded
the high power source to said; lamp in its ejected
by the jacket and full light output from the lamp
is immediately available when the power input 50 position and the low power source to said lamp in
its retracted position.
is increased upon the carriage being ejected from
vapor lamp of the compact source type, a sup
the jacket.
2'. The invention as set forth in claim 1, in
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