Method and apparatus for tuning strip flourescent light fixtures

A tunable high intensity lighting system comprising at least a light enclosure box, an elongated shaped reflector, and a lens. The high intensity lighting system can be retrofitted to existing strip fluorescent light fixtures to adapt the existing fixture to obtain desired lighting characteristics for a specific application. By using different combinations of components, different light intensities, and tint and glare characteristics are obtained. A method for tuning existing strip fluorescent light fixtures also is disclosed, as is a kit for preselected applications, where the kit contains the components for the retrofitting to the existing fixture.

TECHNICAL FIELD 
This invention relates to a method and apparatus for tuning strip 
fluorescent light fixtures to increase the intensity, while improving the 
tint and glare characteristics of existing strip fluorescent light 
fixtures for specific applications. More particularly, this invention 
relates to a tunable high intensity lighting system which may be 
retrofitted by attaching to the existing strip fluorescent housing a light 
enclosure box with fluorescent tube sockets, which encloses and contains 
an elongated shaped reflector, tubes, and a lens which fits at the bottom 
of the light enclosure box. 
BACKGROUND OF THE INVENTION 
Lighting in industrial and other environments presents a number of problems 
in obtaining the desired lighting characteristics for a particular work 
application. Intensity of the light, tint of the light, and glare 
characteristics of the light are some of the major characteristics of the 
light which may need to be adjusted for particular applications. 
Increasing the overall amount of light to obtain the desired intensity may 
also increase the glare from the lighting source which actually can make 
it more difficult to see. Glare is a major contributor to worker fatigue 
and increases the possibility of worker error. Increasing the intensity of 
light from a light source also can present problems with respect to heat 
generated by the lighting source. As an example, enclosed high output 
fluorescent lights require water cooling to perform correctly. The 
increased complexity introduced by water cooling increases the initial 
cost, decreases reliability, increases maintenance costs and is 
undesirable in many industrial applications. 
Attempts to increase the intensity of lighting in desired work areas is not 
as straightforward as it would appear. If, for example, existing strip 
fluorescent light fixtures are being used, simply changing a two tube 
fixture to a four tube fixture may not provide a significant increase in 
lighting intensity in the area in which the lighting is desired, although 
it will certainly increase both glare and operating costs. While new 
fixtures utilizing different types of lighting are an option, in most 
industrial and commercial situations, there already exists a large 
investment in existing high output and other types of strip fluorescent 
light fixtures. Any change to totally new lighting systems, such as 
halogen lights, would require rewiring and re-engineering which would be 
prohibitively expensive for most businesses. 
Other problems with lighting in industrial applications are arising from 
new methods of conducting business among commercial establishments. 
Whether a manufacturer or service company, businesses have adopted methods 
which involve frequent changes in the products they provide and therefore 
the physical facilities that they inhabit. For example, a manufacturer may 
change a product on a yearly basis. Another example is fruit sorting 
establishments where the fruit sorted changes with the season. In 
businesses experiencing frequent changes in their physical plant, there is 
a need for commercial lighting that can be readily adjusted to the new 
requirement. Unfortunately, most existing fixtures do not provide much 
flexibility in adapting the light fixture for different levels of 
intensity, tint control, or glare characteristics. The only options may be 
to change the types of tubes in an existing fixture which has a limited 
effect, or have different fixtures for different applications, which also 
can be prohibitively expensive. 
As seen from the above discussion, there are a number of desirable 
characteristics for tuning strip fluorescent light fixtures to improve the 
intensity, tint, and glare characteristics in existing strip fluorescent 
light fixtures. It would be desirable to have a high intensity lighting 
system which can be retrofitted to an existing strip fluorescent light 
fixture. It also would be desirable to have a high output strip 
fluorescent light fixture which can be adjusted for intensity, tint, and 
glare characteristics of the light it emits. Further, it would be 
desirable to have a high output strip fluorescent light fixture which 
would be used without special cooling requirements or rewiring. 
While the discussion here relates to a method and apparatus for tuning 
strip fluorescent light fixtures to improve the intensity, tint, and glare 
characteristics in existing strip fluorescent light fixtures, it is not 
intended that the invention be limited to this situation. It will be 
obvious from the description that follows that the present invention will 
be useful in other applications with problems common to those described 
herein. 
DISCLOSURE OF THE INVENTION 
It is an object of the present invention to provide a tunable high 
intensity lighting system which can be retrofitted to existing strip 
fluorescent light fixtures. 
It also is an object of the present invention to provide a tunable high 
intensity lighting system which is adjustable in intensity, tint, and 
glare characteristics of the light emitted so that these characteristics 
can be adapted for a specific environment or task. 
It is a further object of the present invention to provide a tunable high 
intensity lighting system which can be adapted to provide light for two or 
more work stations from a single fixture where the lighting 
characteristics for the two or more work stations vary in intensity, tint, 
and glare characteristics. 
It is an additional object of the present invention to provide a method for 
adjusting the intensity, tint, and glare characteristics of light emitted 
from an existing strip fluorescent light fixture to the desired levels for 
a specific application. 
It is another object of the present invention to provide a kit which allows 
an existing strip fluorescent light fixture to be upgraded to a tunable 
high intensity lighting system. 
The present invention achieves these and other objectives which will become 
apparent from the description that follows, by providing a high intensity 
lighting system which includes at least a light enclosure box, an 
elongated shaped reflector, and a lens. The light enclosure box has sides, 
a top and an open bottom. The light enclosure box is attachable to an 
existing strip fluorescent housing by an attachment system. The elongated 
shaped reflector fits within the light enclosure box, and is curved 
downward toward the bottom of the enclosed box. High output fluorescent 
tubes fit within the shaped reflector and are plugged into strip 
fluorescent sockets inside the top of the light enclosure box. Attached to 
the enclosure light box bottom is the lens. In this embodiment, the 
elongated shaped reflector, tubes, and lens can all be interchanged to 
adjust the light intensity, tint, and glare characteristics to achieve a 
desired lighting effect for a particular application. 
An alternative preferred embodiment constructed in accordance with the 
present invention provides a kit for tuning strip fluorescent light 
fixtures which includes at least a light enclosure box, an elongated 
shaped reflector, and a lens. In this embodiment, the kit is packaged as a 
unit to be retrofitted for specific applications where the correct 
combination of components to achieve the desired lighting has been 
predetermined. 
Another alternative preferred embodiment in accordance with the present 
invention provides a method for tuning existing strip fluorescent light 
fixtures for particular applications is provided. In the method of this 
preferred embodiment, the combination of high output ballast, light 
enclosure box, elongated shaped reflector, fluorescent light sockets, high 
output fluorescent light tubes, and lens is determined that will result in 
the emitted light with the desired characteristics. After the correct 
components have been determined, they are installed on the existing strip 
fluorescent housing as needed. 
In this method of alternative preferred embodiment, the installation of the 
selected components can include the steps of removing the ballast, 
reflector, sockets, and tubes from the existing strip fluorescent light 
fixture, leaving the existing strip fluorescent housing in place. A high 
output ballast can be placed within the existing strip fluorescent 
housing, if needed. Then, the light enclosure box with the shaped 
reflector is attached to the existing strip fluorescent housing. After the 
light enclosure box is attached, the high output fluorescent tubes are 
plugged into the fluorescent light sockets and the desired lens is 
attached to and substantially covers the bottom of the light enclosure 
box. 
In yet another alternative preferred embodiment in accordance with the 
present invention, a translucent screen is attached to the lens so that 
the translucent screen substantially covers the lens. Such a screen can be 
used to change the tint of light emitted by the fixture and/or reduce the 
intensity of the light fixture. 
A further alternative preferred embodiment in accordance with the present 
invention uses a shaped reflector can be tinted to change both the 
intensity and the tint of the lighting emitted by the fixture. 
An additional alternative preferred embodiment in accordance with the 
present invention uses the curved elongated reflector is divided laterally 
so that a first section of it is tinted and a second section is tinted 
differently or not at all, thereby allowing light with two different 
characteristics to be emitted from a single fixture. This enables a single 
fixture to provide lighting for work areas requiring two different types 
of lighting. Also, in this alternative preferred embodiment, the lens can 
be divided into two sections that correspond substantially to the first 
and second sections of the elongated shaped reflector. The use of 
different lenses can further enhance the tuning of light for two different 
work stations. 
Other additional alternative preferred embodiments in accordance with the 
present invention can result from different combinations of preferred 
embodiments described above, or elements of those embodiments in different 
combinations.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
With reference to FIG. 1 a high intensity lighting system 20 is shown. The 
high intensity lighting system has a light enclosure box 22 with sides 24 
a top 26 and a substantially open bottom 28. The light enclosure box is a 
hollow, substantially enclosed box with the exception of its substantially 
open bottom. Fitting within the light enclosure box is an elongated shaped 
reflector 30. Along its length, the elongated shaped reflector is 
substantially straight while laterally it has a shape that opens downward. 
This lateral shape is substantially uniform for the length of the 
elongated shaped reflector. The elongated shaped reflector has an inner 
surface 34 which reflects light from inside the light enclosure box. Two 
high output fluorescent tubes 36 fit within the inner surface of the 
elongated shaped reflector. Attached to and substantially covering the 
substantially open bottom is a lens 38. 
The high intensity lighting system 20 is retrofitted to an existing strip 
fluorescent light fixture 40, as shown in FIG. 3. After the existing 
fluorescent tubes 42, and reflector 44 are removed from the existing strip 
fluorescent light fixture, a strip fluorescent housing 46 is left. The 
ballast (not shown) may or may not be removed. It is this component that 
is wired into the ceiling, wall, etc., in the commercial and industrial 
application. 
To install the high output strip fluorescent light fixture 20, the light 
enclosure box 22 is attached to the strip fluorescent housing 46. The 
light enclosure box top 26 has slots 50 which enables the fluorescent 
light sockets 52 to extend within the light enclosure box. The light 
enclosure box can be affixed to the strip fluorescent housing using 
attachment mechanisms, such as twist and lock devices 54, as shown in FIG. 
1 which pass through holes 56 in the light enclosure box top 26 and holes 
58 in the existing strip fluorescent housing. The twist and lock devices 
are practical, but screws, nuts and bolts, and any number of attachment 
mechanisms common and well known in the mechanical arts would be equally 
desirable and useful. 
After the light enclosure box 22 has been attached to the strip fluorescent 
housing 46, the elongated shaped reflector 30 is installed within the 
light enclosure box. The elongated shaped reflector is slightly shorter 
than the length of the light enclosure box, and is short enough to fit 
between the fluorescent light sockets 52 which are located proximate the 
ends of the strip fluorescent housing in corresponding pairs. The 
elongated shaped reflector can be attached to the light enclosure box by a 
variety of means of mechanical devices, including screws 60 that are 
shown. 
High output fluorescent tubes 62 are plugged into the fluorescent light 
sockets 52 of the strip fluorescent housing 46. After the tubes are in 
place, the lens 38 is fitted to the light enclosure box 22. High output 
fluorescent tubes are well known in the art and readily available from 
commercial sources. 
The lens in this particular embodiment actually fits within the light 
enclosure box and rests upon edges 64 which extend inward from the light 
enclosure box sides 24 at the light enclosure box bottom 28. This way of 
attaching the lens to the light enclosure box allows the easy access to 
the interior of the light enclosure box for repair or replacement of 
components without the necessity of additional attachment mechanisms. At 
the same time, the lens could also be affixed to the bottom of the light 
enclosure box by screws or similar attachment means, or even attached to 
the light enclosure box bottom by a material such as a hook and loop 
material, like Velcro. 
Both the light enclosure box 22 and the elongated shaped reflector 30 can 
be made from any number of materials which provides sufficient structural 
strength, and at the same time, are lightweight to function correctly and 
fabricate economically. Common sheet steel has been used with success and 
it is anticipated that other metals such as aluminum could be used with 
equal success. Some plastic materials which can be fabricated with high 
rigidity and which are reasonably temperature resistant also could be used 
in the fabrication of the light enclosure box and the elongated shaped 
reflector. 
The drawings show two-bulb strip fluorescent light fixtures, but this 
should in no way be interpreted as a limitation on the structure of the 
invention. This invention works equally well with tube configurations from 
one tube to four or more tubes. Any existing strip fluorescent light 
fixture can be replaced with an embodiment of the present invention. Of 
course, the size of the light enclosure box can vary with the size and 
number of tubes for a specific configuration. By way of example, a size of 
light enclosure box that has been used with success with an existing strip 
fluorescent light fixture with two tubes is 96 inches (243.9 cm) in 
length, 12 inches (30.5 cm) in width, and 4 inches (10.2 cm) in depth. 
Typically in commercial and industrial applications, existing strip 
fluorescent light fixtures are high output fixtures, such as light fixture 
40 shown in FIG. 3. If the high intensity lighting system 20 is being 
retrofitted to an existing high output strip fluorescent lighting fixture, 
the ballast and fluorescent light sockets 52 in the existing fixture may 
not need to be changed. If the existing ballast is removed, a high output 
ballast 48 is installed as a replacement in the strip fluorescent housing 
46. A typical high output ballast has an output of approximately 800 
milliamps, as opposed to the output of a ballast for a standard strip 
fluorescent light fixture of approximately 460 milliamps. There are also 
very high output strip fluorescent light fixtures which use ballasts that 
have an output of approximately 1500 milliamps. (Note that separate 
figures for standard or very high output strip fluorescent light fixtures 
are not shown). They are substantially similar to high output strip 
fluorescent light fixtures. 
Since industrial or commercial situations do typically use high output or 
even very high output strip fluorescent light fixtures, the high intensity 
lighting system 20 does not necessarily include a replacement ballast 48 
or fluorescent light sockets 52, although it can. In other applications, 
the high intensity lighting system can be retrofitted to a standard strip 
fluorescent light fixture to improve the intensity, tint, and glare 
characteristics of the standard fixtures also. Even if the standard 
ballast is not replaced with a high output ballast, the use of the light 
enclosure box 22, the elongated shaped reflector 30, and lens 38 can cause 
dramatic improvements and allow tuning of the standard strip fluorescent 
light fixture. Even greater improvements can be obtained by retrofitting a 
high output ballast 48 in the existing strip fluorescent housing 46 of the 
standard strip fluorescent light fixture, but such an adaptation requires 
that fluorescent light sockets 52 for high output fluorescent light tubes 
36 also be fitted to the fluorescent light housing of the standard strip 
fluorescent light fixture. The high intensity lighting system 20 also may 
be adapted to existing low output strip fluorescent light fixtures, which 
use a ballast of approximately 260 milliamps. 
A high intensity lighting system 20 constructed in accordance with the 
present invention allows a user to adjust the light emitted by the fixture 
to obtain the desired characteristics of intensity, tint, and glare by 
changing both the elongated shaped reflector 30 and lens 38 either 
separately or together. Another characteristic that is adjusted during the 
retrofitting of the high intensity lighting system is the size of the area 
affected by the light from the retrofitted strip fluorescent light 
fixture. This characteristic is closely related to the light intensity of 
the fixture. Different combinations of components directly affect the size 
of the work area that is illuminated by the fixture. Different lens 38 and 
elongated shaped reflectors 30 can either expand or shrink the area 
illuminated by the fixture. 
FIG. 5A-5C illustrate just some of the configurations of the lateral shapes 
available in the elongated shaped reflectors 30a, 30b, and 30c for use 
with the present invention, although these examples are in no way 
exhaustive. In addition to the variations in shape configuration of the 
elongated shaped reflector, the finishes of the inner surfaces 34a, 34b, 
and 34c also effect the intensity, tint, and glare characteristics of the 
light emitted by the light fixture. Specular, or highly reflective, 
finishes are desired when higher intensity light is desired. Also the 
inner surface can be tinted with a colored, translucent film to change the 
tint of the light emitted from the high output strip fluorescent light 
fixture while retaining high reflectivity. Also, the inner surface can be 
painted which can reduce the intensity of the light emitted as well as 
effecting the tint of the light emitted. The shape configurations of the 
elongated shaped reflector specifically affect the size of the area 
illuminated by a fixture retrofitted with the high intensity lighting 
system 20. 
As illustrated in FIGS. 6A-6C, a variety of lenses 38a, 38b, and 38c are 
also available. Each of these lenses have a plurality of adjoining 
apertures 66a, 66b, and 66c through which light is emitted. The plurality 
of apertures together form a light permeable grid that is substantially 
equal to or larger than the open light enclosure box bottom. The size and 
shape of the apertures effects both the intensity and the glare 
characteristics of the light emitted. For example, a lens such as 38b in 
FIG. 6B with smaller apertures 58b emits light with greater intensity but 
will cause more glare if the light fixture is to far above the work 
surface. In contrast, lens 38a in FIG. 6A reduces glare from the light 
fixtures required to be higher from the work surface. 
In addition to the size and shape of the apertures, the lens affects the 
characteristics of the light emitted from the light fixture and the shape 
and finish of the lens walls 68a, 68b, and 68c, which also form the 
portion of the lens connecting the apertures. The lenses illustrated in 
FIGS. 6A-6C have lens walls that are curved inward towards the apertures 
66a, 66b, and 66c at the top 70a, 70b, and 70c of the lens. The lens walls 
have a highly reflective finish, such as a mirrored finish. Thus, the lens 
acts as a reflector also. The shape of the lens walls correspond to the 
portions of a parabolic curve. These features of a lens are shown in 
detail in FIG. 7 which is an enlarged portion of lens 38a. Many types of 
lenses are already commercially available. Success has been achieved using 
a Para-Lite III lens from A.L.P. Lighting and Ceiling Products, Inc. The 
lenses themselves can be made from any number of materials. Success has 
been achieved using high impact plastics. While the apertures shown in the 
drawings are substantially square or rectangular, they are available in 
other shapes such as circular or oval which can be used as is appropriate. 
The only limitations on the curved configurations of the elongated shaped 
reflectors 30 or lens apertures 66 are those of the human imagination 
combined with the practical limitations of size and usefulness. By using 
different combinations of lenses 38 and reflectors the light emitted from 
the light fixture can be "tuned" to a specific application. 
Example of an application where intensity, tint, and glare characteristics 
of lighting is critical are fruit sorting lines. Fruit is passed along 
sorting lines where sorters grade the fruit according to its quality. 
Since the grade of the fruit affects the price which will be paid for the 
fruit it is a critical determination. The fact that fruit varies in color, 
texture, and reflectivity makes it very difficult to sort more than one 
kind of fruit in a single area with a single type of lighting source. By 
using the present invention, a single sorting line could be used to sort a 
variety of fruits where the user would simply change the reflectors and 
lenses to obtain the correct tint, light intensity, and glare 
characteristic to enable sorters to sort a specific fruit. When a 
particular season ended, the elongated shaped reflectors and lenses could 
be changed for the next seasonal produce to be sorted. 
High intensity lighting systems constructed in accordance with the present 
invention, were retrofitted to existing strip fluorescent light fixtures 
as an experimental installation in a company's apple sorting areas. The 
experimental installation occurred after nationwide inquiries indicated 
there were no existing lighting systems that would meet the company's 
lighting needs. After the experimental installation retrofitting the high 
intensity lighting systems was accomplished, employees working in the 
affected areas reported reduced sorting table light glare, and fewer 
associated employee complaints. The reduced glare and associated 
complaints came in the face of significantly increased light levels on 
work surfaces using the high intensity lighting systems installed in the 
existing strip fluorescent light fixtures which improved employee ability 
to sort fruit by more than 30%. This improvement was measured by the 
increased percentage of apples graded properly as a result of the improved 
lighting. Employees also reported much lower eye strain due to the 
improved lighting levels on the working surfaces. 
At the site of the experimental installation, the existing strip 
fluorescent light fixture's light intensity at a work station was 70 to 
150 foot candles, depending on the height of the light fixture. The output 
using a high intensity light system 20 with an elongated shaped reflector 
22a as shown in FIG. 5A and a lens 38b as shown in FIG. 6B, is 270 to 325 
foot candles at the work station with the light fixture 37 inches above 
the work station. Thus, the intensity of the light is improved 
dramatically while workers reported reduced eye strain and an accompanying 
improvement in the ability to perform the work. 
While high output strip fluorescent light fixtures are presently being 
used, they are an open configuration with only a reflector 44 and tubes 40 
as shown in FIG. 3. While there are existing enclosed high output strip 
fluorescent light fixtures, they have to be water cooled to enable them to 
function correctly. Thus, a user who wishes to go to an enclosed high 
output strip fluorescent light fixture is forced to remove the existing 
fixtures completely and to install water cooled fixtures with all of the 
added expense, complications, and reduced reliability incumbent in such a 
system. The water cooling aspect of existing enclosed high output 
fluorescent light fixtures is required due to the heat generated by such 
fixtures. 
With the high intensity lighting system 20 constructed in accordance with 
the present invention, the high output ballast 48 is not contained within 
the light enclosure box 22. Rather, it is contained within the strip 
fluorescent housing 46. The high output ballast, a primary heat source in 
the high output strip fluorescent light fixture, has the existing strip 
fluorescent housing and the light enclosure box acting as heat sinks. 
Thus, the high intensity lighting system enables an existing strip 
fluorescent light fixture to be converted to an enclosed high output strip 
fluorescent light fixture without the expense of a totally new 
installation or water cooling. This is true whether the conversion is from 
open high output fixture to enclosed high output fixture, or even standard 
strip fluorescent light fixture to high output strip fluorescent light 
fixture. 
In addition to using the elongated shaped reflectors with different 
configurations, tint, or paint on the curve inner surface, another device 
which may be used to affect tint and intensity of the light is a 
translucent screen used in conjunction with an existing lens. As shown in 
FIG. 8, one way to use the translucent screen 78 is to simply lay it on 
top of the lens 79 within the light enclosure box 80. This may be 
desirable in applications where the work surface or items to be examined 
are highly reflective and tend toward glare. 
Another embodiment of the present invention makes even fuller use of the 
adaptive properties of the high output strip fluorescent light fixture 
constructed in accordance with the present invention as shown in FIG. 9. 
In this embodiment, of the elongated shaped reflector 82 has a first inner 
surface 84 and a second inner surface 86. The first inner surface 84 has a 
specular finish for high intensity lighting while second inner surface 86 
may be painted to allow a work station where reading is required. This 
adaptability can also extend to the lens 88 which can have a first 
plurality of apertures 90 and a second plurality of apertures 92. An 
example of the use for such an embodiment would be where a fixture 
overlaps a sorting line and an area where reports must to be filled out. 
With this configuration, a single strip fluorescent light fixture can 
provide high intensity lighting for the sorting procedure while providing 
lower intensity lighting for the report writing work station. A variation 
of this embodiment would have an elongated shaped reflector with a single 
curved configuration but with the two portions illuminated by different 
finishes on the curved inner surface. 
In practice, the first step for utilizing an embodiment of the present 
invention would be to evaluate the lighting in the affected area and 
determine the desired characteristics for lighting in the area to optimize 
working conditions. After these determinations have been made, the 
appropriate combination of high output ballast 48, light enclosure box 22, 
elongated shaped reflector 30, fluorescent light sockets 52, high output 
fluorescent light tubes 36, and lens 38 can be selected for installation. 
As information on the appropriate combination of components for specific 
applications is gathered, data bases or "look up" tables can be created as 
reference guides which will enable a quick, efficient selection of the 
correct components for specific applications. An outgrowth of these data 
bases or tables is the ability to set up kits containing preselected 
components to enable the tuning of existing strip fluorescent light 
fixtures to specific applications without the need for individualized 
evaluations or experimentation for installation of a high output strip 
fluorescent light fixture in accordance with the present invention. These 
kits have at least a light enclosure box 22, an elongated shaped reflector 
30, and a lens 38. The kits could also include a high output ballast 48, 
or fluorescent light sockets 52, or high output fluorescent light tubes 
36, the number of components in the package would be dependent upon the 
extent to which components from the existing strip fluorescent light 
fixture could be used. Similarly, kits for tuning strip fluorescent light 
fixtures which have already been retrofitted with the high intensity 
lighting system 20 could be created using primarily just elongated shaped 
reflectors and lenses, since such a light fixture would already have the 
light enclosure box and very probably would have the correct ballast, 
fluorescent light sockets, and tubes. The variation on such kits is 
limited only by the variations on the applications and the desired tuning. 
INDUSTRIAL APPLICABILITY 
This invention would be useful in any situation where it is desirable to 
have a tunable high output strip fluorescent light fixture in which the 
intensity, tint, and/or glare characteristics of light emitted from the 
light fixture can be adjusted for particular applications. 
In compliance with the statute, the invention has been described in 
language more or less specific as to structural features. It is 
understood, however, that the invention is not limited to the specific 
features shown, since the means and construction herein disclosed 
comprised preferred forms put in the invention to effect. The invention, 
therefore is claimed in any of its forms or modifications within the 
legitimate imbalance from the impended claims.