U.S. patent number 3,867,661 [Application Number 05/408,218] was granted by the patent office on 1975-02-18 for quick warm-up lamp.
This patent grant is currently assigned to The United States of America as represented by the Secretary of the Navy. Invention is credited to Robert A. Eckel, Allen R. Waltz.
United States Patent |
3,867,661 |
Waltz , et al. |
February 18, 1975 |
Quick warm-up lamp
Abstract
A quick warm-up lamp, including a gas filled bulb, and a cathode
and an ae mounted in and at opposite ends of the bulb in a spaced
apart relationship. A jacket is disposed about the entire bulb so
as to provide an insulative space between the bulb and the ambient
environment. Each end of the bulb is molded integrally with the
jacket into a solid neck which extends from the respective end and
is located within the jacket. A lead extends through each neck and
is connected to the cathode and the anode, respectively. The above
configuration and a particular combination of additives within the
bulb ensure that the bulb will warm up quickly to produce
light.
Inventors: |
Waltz; Allen R. (San Diego,
CA), Eckel; Robert A. (Cupertino, CA) |
Assignee: |
The United States of America as
represented by the Secretary of the Navy (Washington,
DC)
|
Family
ID: |
23615344 |
Appl.
No.: |
05/408,218 |
Filed: |
October 19, 1973 |
Current U.S.
Class: |
313/26; 313/27;
313/43; 313/571; 313/634; 313/642 |
Current CPC
Class: |
H01J
61/34 (20130101) |
Current International
Class: |
H01J
61/34 (20060101); H01j 061/30 () |
Field of
Search: |
;313/17,26,27,43,220 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Kominski; John
Assistant Examiner: Hostetter; Darwin R.
Attorney, Agent or Firm: Sciascia; Richard S. Johnston;
Ervin F.
Claims
1. A quick warm-up lamp comprising:
a bulb;
a cathode and an anode mounted within and at opposite ends of the
bulb in a spaced apart relationship;
a jacket disposed about the entire bulb so as to provide an
insulative space between the bulb and the ambient environment;
each end of the bulb being molded integrally with the jacket into a
solid neck which extends from the respective end and is located
within said jacket; and
a lead extending through each neck and connected to the cathode and
the
2. A quick warm-up lamp as claimed in claim 1 including:
3. A quick warm-up lamp as claimed in claim 2 including:
each of said necks extending exteriorly beyond the jacket;
a terminal mounted on each exterior end of the necks; and
each of the leads extending through a respective exterior portion
of the
4. A quick warm-up lamp as claimed in claim 3 including:
the bulb and the jacket each being elongated and aligned with one
another along their longitudinal axes; and
said ends of the bulb being located along the longitudinal axis of
the
5. A quick warm-up lamp as claimed in claim 4 including:
said bulb containing xenon, mercury, and thallium iodide; and
the partial pressure ratio of mercury to mercury, xenon, and
thallium iodide being within a range of 0.50 to 0.65 for a
completely vaporized
6. A quick warm-up lamp as claimed in claim 5 including:
the cold fill pressure at standard temperature and pressure being
between 3 and 4 atmospheres; and
said jacket being evacuated.
Description
STATEMENT OF GOVERNMENT INTEREST
The invention described herein may be manufactured and used by or
for the Government of the United States of America for governmental
purposes without the payment of any royalties thereon or
therefor.
BACKGROUND OF THE INVENTION
Man is making his move into the ocean more and more with a myriad
of types of deep submersibles, some of which are manned and others
which are unmanned. The manned submersibles, such as Pisces, are
actively involved in laying cable, salvege, and exploration work.
The unmanned vehicles, such as the Navy's Cable Underwater Recovery
Vehicle (CURV), are mainly involved in salvage work. A recent
example of work performed by CURV was its recovery of two aquanauts
stranded in a Pisces vehicle at 1,600 feet off the coast of
Ireland.
The lighting systems employed by these submersibles, whether they
be manned or unmanned, are extremely important to successful
completion of a mission. The manned Pisces vehicle requires strong
and efficient lighting for enabling the occupants to view
underwater objects in a totally dark environment, and the unmanned
CURV type of vehicles require the same type of lighting for viewing
underwater objects by the use of TV cameras.
In the past the mercury lamp has been used extensively in
underwater applications because its spectral output is concentrated
in small spectral bandwidths, two of which are transmitted quite
well by sea water. However, one of the more undesirable
characteristics of the mercury lamp is the start-up time required
to produce full output radiation. The mercury arc lamp requires up
to 13 minutes to produce full output when the ambient temperature
of the water is 32.degree.F., and as little as 6 minutes when the
water temperature 90.degree.F. This thermal influence on starting
time is explained by the fact that mercury is almost completely
condensed when the temperature of the water is 100.degree.F. or
less, and the operating conditions are achieved only when the arc
volume has been sufficiently heated to vaporize all of the mercury.
This start-up time is a hindrance to submersible operations, such
as the CURV, because the television cameras with which mercury
lamps are being used are relatively insensitive to the low
illumination levels offered by the lamp as it is warming up. This
situation can lead to operational difficulties unless the lamps are
on during the entire mission.
There has been a strong need for an underwater lamp which will have
the efficient output of the mercury lamp, but yet have the quick
start-up capability and rugged characteristics which are desirable
for deep ocean operations. In a mercury lamp which has chemical
additives as the plasma medium, adequate vapor pressures for the
arc current require an envelope whose cold spot (minimum
temperature area) is sufficiently high to maintain desired
constituent partial pressures. Because of the non-uniform heating
effect obtained by the arc of a mercury short arc discharge, the
envelope of the lamp is coated with either a gold or platinum
reflective paint. This coating is usually applied to the upper part
of the lamp bulb where the top of the bulb meets the arm or seal
region of the lamp. When the lamp is tilted from its normal
vertical cathode up orientation, a change in the cold spot
temperature may occur. If this happens the operating pressure of
the discharge can change, and thus the radiating characteristics of
the lamp are altered. This condition can be compensated for by
either increasing the operating power of the lamp, or by applying
additional reflective paint to increase the cold spot temperature
of the bulb. Both alternatives are unsatisfactory, the latter being
most objectionable from the standpoint of optical collection
efficiency. In the instances where short arc lamps are doped with
additives whose vapor pressures are less than that of mercury, cold
spot considerations are even more important, and higher
temperatures have to be maintained.
Higher temperatures are usually obtained by means of placing the
short arc lamp in an outer envelope which is evacuated. By means of
the vacuum layer about the bulb, heat normally removed from the
envelope via convection is now conserved, and thus high bulb wall
operating temperatures are obtained. This means of conserving heat
has distinct disadvantages when the prior art teachings are
followed: (1) breakdown often occurs between the exposed wires
leading into the seals of the arc tube when the high voltage
starting pulse is applied, thereby causing a sub-torr pressure from
out-gassing of the lamp envelope, and (2) the outer envelope is
large and greatly increases the overall size of the lens
structure.
SUMMARY OF THE INVENTION
The problems of slow warm-up and inefficiency of lamps for
underwater applications appeared to reside in the configuration of
the lamp as well as the additives within the bulb. Previous
attempts to solve the warm-up problem by coating the bulb or
placing it in an outer envelope have just brought on other
problems. Prior art attempts to provide different additives for the
bulb have only reduced the efficiency or locked out the desirable
light qualities necessary for underwater work. The present
invention has overcome the slow warm-up problem of lamps used in
underwater work by providing a unique lamp configuration and high
cold fill pressure of the bulb, and has overcome the efficiency
problem by providing a unique combination of bulb additives which
are under optimum partial pressures.
In the unique lamp configuration a cathode and an anode are mounted
within and at opposite ends of a bulb in a spaced apart
relationship. A jacket is disposed about the entire bulb so as to
provide an insulative space between the bulb and the ambient
environment. Each end of the bulb is molded integrally with the
jacket into a solid neck which extends from the respective end and
is located within the jacket. A lead extends through each neck and
is connected to the cathode and the anode, respectively. With this
configuration there is no problem of breakdown of the wire lead,
and yet the advantages of the vacuum jacketing enables quicker
warm-up of the lamp.
Further, the invention provides the bulb with a mixture of chemical
additives which enables efficiency. These additives are xenon,
mercury, and thallium iodide. It has been found that optimum
visible radiant output is enabled by a partial pressure ratio of
mercury to mercury, xenon, and thallium iodide of approximately 0.5
for a completely vaporized thallium iodide dose when the lamp is
fully warmed. Quick warm-up of the bulb is obtained by providing a
high cold pressure of the xenon. This high operating pressure of
xenon quickly increases the bulb temperature which subsequently and
rapidly increases the partial pressures of the mercury and the
thallium iodide.
OBJECTS OF THE INVENTION
An object of the present invention is to overcome the
aforementioned problems associated with prior art underwater
lamps.
Another object is to provide an efficient and quick warm-up
underwater lamp.
Another object is to provide a compact, rugged, quick warm-up and
efficient underwater lamp which can be utilized in all attitudes
and orientations of service.
These and other objects of the invention will become more readily
apparent from the ensuing specification when taken with the
drawings.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a longitudinal cross-sectional view through the
underwater lamp.
FIG. 2 is a graph illustrating efficacy as a function of buffer gas
partial pressure ratio.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawing, there is illustrated in FIG. 1 a
quick warm-up lamp 10 which includes a bulb 12 and a jacket 14. It
is desirable that both the bulb and the jacket be elongated as
illustrated in FIG. 1. The jacket 14 is disposed about the entire
bulb so as to provide an insulative space 16 between the bulb and
the ambient environment. Each end of the bulb is molded integrally
with the jacket 14 into solid necks 18 and 20 which are located in
the jacket and extend in diametrically opposite directions from the
bulb. The bulb 12, jacket 14, and necks 18 and 20 may be
constructed of glass or other suitable transparent material which
can be molded as described hereinabove.
Mounted within the bulb 12 at opposite ends thereof are a cathode
22 and an anode 24. Both the cathode and the anode may be molded
into place within the respective necks 18 and 20 and may be
constructed of thorated tungsten and tungsten respectively. Each of
the necks 18 and 20 may extend exteriorly beyond the jacket 14 and
may be fitted with terminals 26 and 28 at their ends for connection
to an outside electrical source (not shown). Electrical leads, such
as molybdenum ribbon foil, 30 and 32 may be molded in the necks 18
and 20 along their longitudinal axes and may be connected
respectively between the cathode 22 and the terminal 26, and the
anode 24 and the terminal 28. This structure eliminates the
breakdown of the leads and any outgassing of the lamp bulb.
The invention further provides a unique partial pressure ratio of
the additives to the bulb 12. The bulb contains a combination of
xenon, mercury, and thallium iodide. The thallium iodide
particularly promotes the efficiency of the lamp in an underwater
environment by providing a band of light in the 5,300A to 5,400A
region. It has been found that optimum visible radiant emission can
be obtained by utilizing a partial pressure ratio of mercury to the
mercury, xenon, and thallium iodide of approximately 0.5 for a
completely vaporized thallium iodide dose when the lamp is warmed
up. This relationship is illustrated in FIG. 2 which is a chart
illustrating efficacy (lumens per watt) as a function of buffer gas
partial pressure ratio. This ratio is a partial pressure of mercury
to the partial pressures of mercury, xenon, thallium iodide. It can
be seen from this chart that the optimum efficacy is obtained when
the partial pressure ratio is approximately 0.5, and this optimum
generally runs through a range of 0.50 to 0.65. Further, the quick
warm-up characteristic is enhanced by a cold fill pressure of the
bulb 12 with the additives at standard temperature and pressure of
between 3 to 4 atmospheres. This cold fill pressure enables the
xenon quickly to increase the bulb temperature which subsequently
and rapidly increases the partial pressures of the mercury and
thallium iodide.
With the aforementioned configuration of the lamp and the additives
to the bulb an efficient quick warm-up lamp is provided which is
especially adapted for underwater use. The lamp can be used for
purposes other than underwater lighting, such as outdoor lighting
in a large stadium. The lamp is rugged, efficient, and can be
oriented in any desired direction.
Obviously, many modifications and variations of the present
invention are possible in the light of the above teachings, and, it
is therefore understood that within the scope of the disclosed
invention concept, the invention may be practiced otherwise than
specifically described.
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