Note: Descriptions are shown in the official language in which they were submitted.
2233364
LIGHT SOURCE FOR-USE IN: LEAK DETECTION:~
IN HEATING, VENTILATING, AND AIR CONDITIONING SYSTEMS
- THAT UTILIZE ENVIRONMENTALLY-SAFE MATERIALS
BACKGROUND OF THE INVENTION
1. FIELD OF THE INVENTION
The present invention relates to a light source for use
in detecting leaks in heating, ventilating, and air
conditioning systems. Particularly, the present invention
relates to a light source which is able to detect substances
which reemit light at wavelengths greater than the wavelength
of light emitted from the light source.
2. BACKGROUND ART
Because of the damage that chlorofluorocarbon (CFC)
refrigerants are doing to the ozone layer, it has become
necessary to dev~lop alternative refrigerants which are
environmentally "friendly". DuPont, International Chemicals,
and others have developed hydrofluorocarbon (HFC) refrigerants
which are much safer for the environment and have an ozone
depletion factor ranging from zero to a fraction of the ozone
depletion factor of CFC refrigerants.
By means of the addition of certain dyes to the
refrigerants and/or lubricants, such as naphthalimide,
perylene, th;oxanthane, coumar;n, or fluorescene, leaks can be
detected by the presence of a fluorescence existing at leak
sites when exam;ned under l;ght sources having appropriate or
specif;c characteristics. Such leak detection techniques are
2~0J3~
known and described in U. S. Patents 5,357,782 and 5,421,19
which issued to R;chard G. Henry on October 25, 1994, and June~
6, 1995, respectively, both of which are assigned to the same~
assignee as the assignee of the present application.
It has been determined that in detecting the fluorescence
present in such detection applications that optimum visibility
of the fluorescence occurs when the leaks are detected under
a l;ght having an emission wavelength between 300 and 700
nanometers. In the past, ultraviolet light sources have been
utilized for this particular usage, but have not provided the
optimum performance inasmuch as they have generated light
primarily in the ultraviolet range found normally between 300
to 450 nanometer~s.
A search of the background art directed at the subject
matter of the present invention conducted in the U. S. Patent
and Trademark Office disclosed ~he following U. S. Letters
Patent:
4,558,014 4,775,853 5,059,790
5,131,755 5,156,976 5,192,510
5,347,438 5,34g,468 5,394,133
5.399.499 5,441,531
Additional patents known to the Applicant of the present
application include the follow;ng:
4,758,366 5,149,453 5,357,782 5,421,192
None of the above-;dentif;ed patents are believed to
claim, teach, or disclose the novel combination of elements
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and functions set forth in the present invention.
The intent of the present apparatus is to provide a light
source that functions to provide an optimized unit for use in
those industries or technologies that require the aiming of
light in specific wavelengths at a substance to cause
fluorescence. This is done in the leak detection industry, as
well as in the non-destructive testing industry. In both
instances, substances such as dyes will fluoresce brightly
under light sources which emit light in the 300 to 500
nanonmeter range, whereas no, or minimal, fluorescence is
detected under ambient light of typical wavelengths.
Historically, the light sources used for these types of
applications were large alternating current lamps operating on
either 110 to 220 volts. Such lamps, known as PAR 38, were
manufactured by Phillips and other manufacturers. Usually,
such lamps were in the 100 - 200 watt range, producing a
substantial amount of light emitted outside of the desired
range to produce the desired fluorescent response. These
lamps also created a large amount of heat, and required the
use of a ballast which provided add;tional bulk and weight.
Substantially later, self-ballasted lamps were developed
overcoming some of the previous drawbacks. However, they were
prone to relatively long warm-up per;ods and were' very
sensitive to voltage surges wh;ch would cause the light to be
turned off, and subsequently required a lengthy cool-down
period followed by another warm-up period.
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More recently, small direct current lamps.of the halogen~
type, or similar, rich in gases such as xenon were developed.
Such lamps had the advantage of requiring no ballast, were
small in dimension, light weight, and were not subject to
voltage surges or spiking. They also provided portability and
could be powered by batteries. Such lamps, however, did not
provide a great output of light in the desirable ranges, and
therefore did not fluoresce efficiently so as to observe
materials with sufficient brightness to meet the needs of most
users. This was probably the result of the usage of
reflectors, which lack adequate beam focus to cause light of
sufficient candle power at the site of fluorescence, i.e., the
leak site.
Accordingly, it is the object of the present invention to
provide a light source that is small, light weight, not
subject to voltage surges, durable, and produces a large
output of light in the wavelength required to effectively
fluoresce the above-mentioned fluorescent dyes.
SUMMARY OF THE INVENTION
In-the field of leak and cr-ac-k detection and related non-
destructive testing, different dyes are utilized which
fluoresce at different wavelengths. Fluorescence is usually
defined as the reemission of light at wavelengths greater than
the wavelength of light emitted from the light source with
which examination takes place.
The key to the lighting system of the present invention
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l;es in the utilization of tungsten halogen lamps w;th an
integral reflector, which provides an offective lighting
system, with the characteristics being determined by the
reflector design and the included lamp, as well as alignment
of the lamp with the reflector. The usual single-ended
tungsten halogen lamp as described herein is mounted in the
axis of the reflector with the base pointing out from the
reflector apex towards the rear. The reflectors provided are
often focusing reflectors which concentrate the light
generated by the built-in lamp to a more or less small or
defined spot at a distance from the reflector and its ax;s.
Many of the reflectors utilized in the halogen lamps
described utilize faceted or structured sur~faces rather than
smooth surfaces to modify light distribution. This
arrangement improves the evenness of the light and can
increase the beam angle, or smooth or break up the light-dark
edges. Facets on the surfaces of the reflectors range from
fine, scarcely visible grains to clearly visible faceting,
with the effect being correspondingly less or more pronounced.
With the combination of the correct reflector shape, such
lamps are able to finely control focus. Smooth aluminum
reflectors have been utilized but do not permit the geometric
balances and dimensional stability that are provided by the
glass reflectors found in newer halogen lamps. Accordingly,
the material choice for such reflectors is usually glass, with
the inner domed reflector surface being suitably coated to
220~364
obtain the required reflective properties. These coatings are~
generally applied by vapor deposition. It is known that suchs
glass reflectors have absolute dimensional stability and a
surface that can be readily modified by applying coatings to
the reflective surface.
Most recently, lamps, including precision engineered
aluminum reflectors, have been developed. The combination of
a high performance axial filament lamp with innovative faceted
reflector designs resulted in producing a lamp having
extremely high center beam candle power and a smooth beam
pattern. Such lamps, with their durable, light weight faceted
reflectors, have proved satisfactory for many of the same
applications wherein glass lamps with an inner domed~faceted
reflector surface have been employed.
When material to be examined requires detection of
fluorescence, the wavelength of the light to be emitted from
the light source is to be more closely defined. Such
precision of definition and control of wavelength may be
controlled by use of reflectors with faceted surfaces.
Some white-light reflectors fluoresce dyes extremely well
in that most fluorescent dyes are excited to fluorescence by
light in the same nanometer range included in the output from
the wh;te-l;ght reflectors, i.e., from 400 to 700 nanometers.
Light produced outside these ranges is largely wasted and will
not produce the desired fluorescence and can detract from the
ability of a user to clearly see the fluorescence. Thus,
.
2203364
faceted reflectors, are ideal in providing proper-excitation~
wavelengths (for fluorescing materials) and providingr
precision not possible using other types of reflectors.
Such lamps are also effective at the spectral width in
the range required for fluorescence, providing extremely
strong intensity of light with the accurate focusing required
for leak detection technology. Such an arrangement results in
a focal point that can produce as high as 50,000 candle power
from extremely small light sources, especially for beam
spreads of 4~ to 11~. In general, the narrower the beam
spread, the greater the candle power and the greater the
intensity of fluorescence created.
It is also possible to more narrowly define the spectral
output from such reflector lamps by the utilization of optical
filters. Light output from the reflector lamp is reduced to
pass only the desired wavelength for the application.
Generally, it is possible for two types of filters to be
utilized, which may be absorption or dichroic filters. The
dichro;c filters operate on the principal of interference.
Additionally, it may be possible to further tailor light
output from light sources in accordance with the present
invention by the utilization of shields or eyewear by the user
to permit only light of certain wavelengths to pass through.
This eyewear can take several forms, including glasses,
goggles, and face shields. Thus, the eyewear, when used in
combination with filters, permits the ultimate fine tuning of
220''364
wavelength for detection of fluorescence.
In the arrangement taught in the present invention,
components consist of a housing wherein there is mounted a
light source, including a reflector with a lamp included
therein, with a reflective faceted surface surrounding the
portion of the lamp that includes the filament. In addition,
ahead of the lamp assembly is a filter lens, which in most
cases is an absorption type filter that acts to further
restrict the part;cular wavelength of the light emitted from
the light source, controlling the light emitting therefrom to
within the specific range reflected by the faceted reflector.
An on/off switch is also included within the container
that provides control of the connection to an external power
source for the light source. Thus, it can be seen that by
means of the combination of the faceted reflector and an
absorption-type filter placed ahead of the light source~ a
predetermined narrowed beam of light will be emitted from the
-light source of the present unit. Additional features and
advantages of the invention will become apparent from the
detailed description of the preferred embodiments of the
invention as set forth in the following.
BRIEF DESCRIPTION OF THE DRAWINGS
Preferred embodiments of the invention will be described
in detail with reference to the accompanying drawings wherein:
FIG. 1 is a sectional view of a light source for use in
examination of substances which reemit light at a wavelength
~ CA 02200364 1998-02-16
greater than the wavelength of the light emitted from the
light source in accordance with the preferred embodiment of
the present invention.
FIG. 2 is an exploded view of a light source in
accordance with the present invention.
FIG. 3 is a perspective view of eyewear including
long wavelength pass material for use in conjunction with
the light source of the present invention.
FIG. 4 is a perspective view of a shield including
long wavelength pass material for use in conjunction with
the light source of the present invention.
DETAILED DESCRIPTION OF THE P~RED EMBODlr-h.~l~
The present invention will best be understood by
reference to the drawings wherein similar components are
designated by the same referenced numerals.
Referring now to FIGS. 1 and 2, the preferred
embodiment of the light source of the present invention
consists of a housing constructed of phenolic, plastic or
suitable material. The unit is cylindrical in construction
and hollow and has affixed at either end thereto front cap
2 and rear cap 3, both caps being constructed of aluminum
or other suitable materials. As may be seen in the
drawings, front cap 2 is open to the exterior and has
positioned directly behind it filter lens 4, which in the
preferred embodiment consists of a BSI lens filter, No.
PS-600. This filter provides maximum transmission of light
at a wavelength of approximately 400
~ CA 02200364 1998-02-16
nanometers, wherein about 82% of the light at that
wavelength is transmitted through the filter lens.
Located directly behind the filter lens 4 is a
compression spring 5 which aids in positioning the lens and
reflector 6 in proper spacial relationship within the
housing and further provides some shock-absorbing
assistance.
- 9A -
220J364
Reflector 6, located behind f;lter lens~r4 and separated
by compression spring ~, is either a molded glass- reflector-
with an aluminized reflective faceted surface (TRU-AIM
BRILLIANT MR16) or an aluminum reflector having a faceted
surface (AR70).
It has been determined that as an alternative lamp 10 can
utilize-the Model AR111 lamp manufactured by Osram-Sylvania.
This is an aluminum reflector lamp including a precision
engineered faceted aluminum reflector which includes a
precision mounted ultraviolet stop bulb. This unit produces
excellent characteristics for reemission of fluorescent
materials and provides a 4~ beam spread. Slightly larger than
the AF~70 lamp indicated above, the housing would have to be
increased proportionately. It has also been determined that
this lamp produces excellent results (between 325 and 700
nanometers) without the use of filters between the substance
to be examined and the lamp.
Most of the reflectors are used extensively to produce
low-voltage, high-intensity lamps utilized for applications
such as display lighting. As previously indicated, molded
reflectors of the type described are typically finished with
a faceted reflective front surface 9. This surface is
configured to reflect visible light from the reflector. The
front surface 9 is provided with facets 7A, while providing a
uniform beam of ;llumination from lamp 10. The particular
(tungsten halogen) lamp chosen herein provides a narrow spot
CA 02200364 1998-02-16
type of beam. Extending from back surface 8 of reflector 6
is mounting portion 14. Lamp 10 has a filament portion lOA
and a neck portion lOB, including therein is filament 11,
which is connected at its rear to terminal 12 and terminal
13 (not shown). (Terminal 13 is not visible in the present
view because it is parallel to terminal 12.) This light
source is normally an incandescent light source, such as a
halogen bulb, with the envelope consisting of filament
portion lOA and neck portion lOB being constructed of glass
or quartz. Lamp 10 is mounted in mounting portion 14 with
the filament portion lOA extending beyond the front surface
9 of reflector 6. A socket 15 receiving terminals 12 and
13 provides connections to circuit conductors 16 and 17.
Socket 15 is constructed of ceramic or similar material.
Conductor portion 16A extends to on/off switch 18 and
continues through conductor portion 16B to an external
power source 20. The other conductor 17 extends directly
from socket 15 to the power source 20.
Either of the lamps, as described herein, typically
operates from a 12 volt source and draws approximately 50
watts of power. The power source 20 may consist of a
battery, generator or dynamo. Switch 18 is utilized to
turn the light source on or off during usage of the present
novel light source to examine substances which reemit light
at wavelengths greater than the wavelength of the light
emitted from the light source of the present invention.
Heat shield 19 extends around the rear portion of
CA 02200364 1998-02-16
reflector 6, mounting portion 14, and socket 15, and is held
- llA -
- 2200364
9fi~
in plAce aga;nst the rear Of reflector 6 by means of portions
of rear cap 3. ~he heat ~h;eld ~ist~ in m~intaining the
pre~ent unit as comfortable to the to~ch ~uring ~perat;on.
It should be not~d that fa~eted refl~ctors ~s sho~n
comple~ with a halogen lamp inclu~ed there;n are av~ ble
fr~m Osr~m-Sylvania Rnd other ~ources as noted previously.
~he 1amp 10, pref~rably is bonded to mounting portion 14
probably by means of a suitable adhesive, ~uoh aB a si licon or
epoxy base~ ~dhc~; ve .
It should be noted that the unit as described inclu~es a
faceted reflector. Fac~ted refle~tors produce spe~;fic
refleetion propertieg through the phenomenon Pf ;nterfer~nce.
The effe~ivene~ of the light sour~e is 0nhan~ed when
the u~er utili~es a shield 40 or eyewsar 30 incl~ding long
w~velength pass n~ateri~l 31 or 41 to further restri~t the
wavslen~th of li~ht from the llght source of the present
invention.
While but ~ sinyl~ embodiment of the present invention
has been shown, i~ will be obvi~us to thos~ skilled in the art
th~t numerous modifications may be m~de w;~ho~t departin~ from
the spir~t of the pre~ent invention, which sh~ll be lim;ted
only by the scope of the claims appende~ hereto.
