Bifurcated randomized fiber bundle light cable for directing light from multiple light sources to single light output

A fiber optic light cable can transmit light from one or more of multiple light originating areas to a light issuing end of the light cable. A main bundle of optic fibers extends from the light issuing end (or cross-sectional area) of the light cable to a bundle junction area of the light cable. At this bundle junction area, the individual fibers are split into at least two bundle segments. The positions of all the individual fibers of the multiple segments are approximately randomized in the main bundle so that by the time they reach the light issuing end (or cross-sectional area) of the light cable, they are approximately random in position with respect to one another. This produces a generally consistent light spread regardless of which light originating area is illuminated. The light cable can be employed in conjunction with a light box having two or more lamps so that when one burns out, another may be quickly activated to continue illumination at the distal end of the tool. Alternatively, multiple lamps may be operated simultaneously to increase illumination.

FIELD OF THE INVENTION 
This invention relates in general to illumination systems for tools 
requiring a beam of directed light to illuminate a working area or target 
object and, in particular, to a fiber optic cable connectable between such 
a tool and a light box. More specifically, but without restriction to the 
particular embodiment hereinafter described in accordance with the best 
mode of practice, this invention relates to a bifurcated single head light 
bundle for use with a light box having a pair of lamps capable of being 
illuminated consecutively to provide extended operating time for the tool. 
BACKGROUND OF THE INVENTION 
There have previously been proposed a number of imaging tools for probing 
into generally inaccessible passageways or cavities to locate a target 
object or a particular working area. These tools include endoscopes and 
laparoscopes used for diagnostic imaging purposes in the medical fields 
and borescopes as employed in non-medical applications such as inspecting 
turbine engines or other mechanical devices. These imaging devices 
typically include a probe having a head portion with an illumination 
system for illuminating the target object or working area, an imaging 
system, and a video monitor for viewing an image of the object or area 
under investigation. 
In the medical field, recently developed minimally invasive surgical 
techniques include endoscopic and laparoscopic examining methods. 
Endoscopic methods generally encompass visualization of internal body 
structures by use of an endoscope which is inserted into an orifice or 
through a previously positioned trocar. Laparoscopy generally refers to 
visual examination of the interior of the peritoneal cavity by use of a 
laparoscope introduced into the cavity through the abdominal wall or the 
vagina. The illumination system of the endoscope or laparoscope typically 
includes a light box and a fiber optic cable connectable between the scope 
and the light box. The scope or probe itself also includes fiber optics 
for transmitting light from the cable to the probe head. In this manner, 
the scope is manipulated so that an object or area of interest can be 
positioned adjacent the head and directly illuminated. The imaging system 
of such scopes or imaging tools may include a charged coupled device (CCD) 
imager chip positioned in the head of the tool and associated circuitry 
for receiving an image of the object or area positioned near the head of 
the probe and transmitting that image to the video monitor. The image 
processing circuitry converts raw video information received from the 
imager chip into a monitor ready standard format signal suitable for the 
particular video monitor. This includes, for example, a standard NTSC, 
, or Secam color video signal. 
Surgeons performing minimally invasive medical operations commonly employ a 
method of triangulation in association with endoscopic or laparoscopic 
examining techniques. This method of triangulation involves the use of an 
endoscope or laparoscope as an imaging tool and at least two other 
surgical instruments introduced into the surgical site through a body 
orifice or by use of a trocar. The surgeon observes a displayed image of 
the target object or working area on the video monitor and performs the 
desired surgery in a minimally invasive manner by manipulating and 
operating the surgical instruments deployed in accordance with the 
techniques of triangulation. During this type of surgical procedure, 
proper functioning of the scope's illuminating system is critical. In the 
event the source of illumination in the light box fails, the image on the 
video monitor will quickly fade to black thus making the surgeon's task 
impossible. In this situation, the medical procedure must be interrupted 
and the equipment problem corrected before surgery can resume. This type 
of illumination source failure is typically encountered when the source 
lamp simply burns out at the end of its expected life. 
OBJECTS AND SUMMARY OF THE INVENTION 
It is, therefore, an object of the present invention to improve imaging 
tools. 
Another object of this invention is to extend the operating time of an 
illumination system used in conjunction with an imaging tool. 
It is a further object of the present invention to adapt a bundle of optic 
fibers to receive direct light from at least two independently activated 
sources of illumination. 
Still another object of the present invention is to avoid the burning out 
of a source lamp in a light box used in conjunction with an imaging tool, 
from interrupting a procedure involving reliance on the tool. 
An additional object of the present invention is to split a bundle of optic 
fibers into at least two end segments each positioned to receive direct 
light from a corresponding independently activated source lamp provided in 
the light box of an illumination system used in conjunction with an 
imaging tool. 
It is a further object of the present invention to allow a surgeon using an 
endoscope or laparoscope as an imaging tool during a minimally invasive 
surgical procedure, to continue the procedure when a light box source lamp 
burns out by simply activating a second source lamp provided in the light 
box. 
Yet another object of the present invention is to split a bundle of optic 
fibers into at least two end segments each positioned to receive direct 
light from a corresponding independently activated source lamp provided in 
the light box of an illumination system used in conjunction with an 
imaging tool so that a second lamp may be quickly activated to double the 
light output at the distal end of the tool. 
Still another object of the present invention is to reduce the difference 
in the view available to the surgeon or other user when one source lamp 
turns off and a second is activated, by randomizing which respective end 
segment individual fibers of the combined fiber optic bundle are placed 
into. 
These and other objects are attained in accordance with the present 
invention wherein there is provided a light cable for transmitting light 
from one or more of multiple light originating areas to a light issuing 
end of the light cable. A main bundle of optic fibers extends from the 
light issuing end (or cross-sectional area) of the light cable to a bundle 
junction area of the light cable. At this bundle junction area, the 
individual fibers are split into at least two bundle segments. The 
positions of all the individual fibers of the multiple segments are 
approximately randomized in the main bundle so that by the time they reach 
the end (or cross-sectional area) of the light cable, they are 
approximately random in position with respect to one another. This 
produces a generally consistent light spread regardless of which light 
originating area is illuminated. 
In a more specific embodiment of the invention, a light cable for 
transmitting light from a light source to a distal end of an imaging tool 
requiring a beam of directed light to illuminate a working area or target 
object is provided. In this embodiment, at least the main bundle of the 
above described light cable is provided with a flexible outer cable member 
including at least one layer of protective material, with the main bundle 
of optic fibers contained within said flexible outer cable member, a first 
adaptor connected to a first end of the light cable for connecting the 
first end of the light cable to an imaging tool, and a second adaptor 
connected to a second end of the light cable for connecting the second end 
of the light cable to a light box. 
According to another aspect of this invention, the second adaptor is formed 
to split the bundle of optic fibers proximate the second end of the light 
cable into at least two end segments each being directed with a 
predetermined orientation so that light directed into any one of the at 
least two end segments is transmitted to the first end of the light cable. 
In accordance with further aspects of the present invention, the second 
adaptor means is provided with a base member secured to the second end of 
the light cable and a hollow shaft member extending from the base member 
for insertion into the light box. The hollow shaft member includes a 
distal end and a proximal end secured to the base member, and is further 
provided with a head member secured within the distal end of the hollow 
shaft member. The bundle of optic fibers is extended through the base 
member and the hollow shaft member, and then directed into the head member 
which is provided with an exterior bevelled surface for each of the at 
least two tip segments. Each of the fiber optic end segments terminates 
with an optically polished surface that is coplanar with its respective 
bevelled surface on the head member. 
According to yet another aspect of this invention, the light box used in 
conjunction with the light cable is provided with at least two independent 
sources of illumination, each having a predetermined orientation to direct 
light into a corresponding tip segment formed on the second end of the 
light cable. The at least two light sources are independently wired so 
that they may be consecutively operated to extend the operating time of 
the imaging tool. Thus, a procedure involving reliance on the tool does 
not need to be interrupted when one of the light sources burns out.

DETAILED DESCRIPTION 
Referring now to FIG. 1, there is shown a light box 10 and a bifurcated 
light cable 12 in accordance with the present invention. The light box 10 
includes a 112 volt AC input which is converted to direct current in a 
smart switching DC power supply generally referenced 16. Power from the 
supply 16 is used to power a pair of ballasts 18--18. Each ballast powers 
and controls a lamp 20 while each of the two lamps 20 is part of a lamp 
assembly 22. A related type of single ballast and lamp apparatus is fully 
disclosed in U.S. Pat. No. 5,291,100 entitled "Low Watt Metal Halide Lamp 
Apparatus" issued to R. J. Wood Mar. 1, 1994 and assigned to the assignee 
of the present application. 
As illustrated in FIG. 1, each of the lamps 20 includes a reflector 24 
formed in the shape of a truncated ellipsoid. The reflectors 24 are 
oriented in the lamp assembly 22 to direct light from the lamps at a right 
angle relative to each other and generally toward a light port 26. The 
lamps 20 employed in the light box 10 may be selected from the type of 
metal halide lamps disclosed in the commonly assigned U.S. Pat. No. 
5,083,059 entitled "Electrode For Metal Halide Discharge Lamp" issued to 
T. W. Graham et at. Jan. 21, 1992. The lamps 20 are preferably such metal 
halide arc discharge lamps having a power input rating within a range of 
between about 1.5 watts and 35.0 watts. The intensity of the output of the 
lamps 20 directed toward the light port 26 is mechanically controlled by a 
light control vane 28 positioned adjacent each of the lamps. The control 
vanes 28 are adjusted by an operator by use of a lamp intensity control 
knob 30 positioned on the front of the light box 10. An on/off toggle 
switch 32 is provided to switch the light box between an operating 
condition and a completely shut-down, unpowered condition. A cooling fan 
34 is provided to remove heat from the interior of the light box 10 during 
operation thereof. 
The bifurcated light cable 12 used in conjunction with the above-described 
light box 10, will now be discussed in detail with particular reference to 
FIGS. 2 and 3. The light cable 12 includes a proximal end 36, a distal end 
38, a mid-section 40, and an internal main bundle of optic fibers 42. The 
mid-section 40 is formed of at least one flexible outer cable covering or 
sheath which contains substantially the entire length of the fiber optic 
main bundle 42. The distal end 38 of the light cable 12 is adapted to 
connect into any one of a variety of imaging tools such as video medical 
endoscopes or industrial borescopes to provide illumination for a target 
object or area under inspection. The proximal end 36 of the light cable 12 
includes an adaptor 44 for securely yet detachably connecting the light 
cable 12 into the light port 26 of the light box 10. 
The adaptor 44 includes a base member 46, a hollow shaft member 48, and a 
head member 50. The hollow shaft member 48 includes a proximal end 52 
secured to the base member 46, and a distal end 54 into which the head 
member 50 is secured. As best illustrated in FIG. 3, the head member 50 is 
comprised of two tip segments 56--56 which split the main bundle of optic 
fibers 42 proximate the distal end 54 of the shaft member 48 into least 
two fiber bundle end segments 42a and 42b. The two fiber bundle end 
segments 42a and 42b split from one another at bundle junction area 43. In 
order to ensure that the light pattern produced by the light cable 12 is 
as identical as possible regardless of through which fiber bundle end 
segment 42a or 42b the originating light passes, the fibers of main bundle 
42 are randomized through a process well known in the art for randomizing 
optical fibers to achieve consistent light spread for a single bundle. In 
this way the individual fibers held by either end segment are positioned 
more or less randomly at some cross-section of the main bundle at or prior 
to the light emitting end of the bundle, so that their positional (and 
light emitting) pattern is approximately randomized. 
As shown in FIGS. 4-7, each of the tip segments 56 are preferably identical 
and include a half-round annulus 57 such than when the two tip segments 56 
are assembled together, the two half-round annuluses 57 form a collar 58 
which is securely fit into the distal end 54 of the hollow shaft member 
48. Each of the bundle end segments 42a and 42b is directed through a 
corresponding hole 59a and 59b, respectively, with a predetermined 
orientation so that light from one of the lamps 20 is directed straight 
into one of the end segments 42a or 42b. Each of the tip segments 56 is 
provided with a bevelled surface 60 onto which one of the corresponding 
holes 59a or 59b opens. In the present embodiment, the two bevelled 
surfaces 60 are oriented ninety (90) degrees to each other. 
With reference again to FIGS. 2 and 3, it is shown that the base member 46 
is provided with a centering pin 62 corresponding to a receptical aperture 
63 (FIG. 1) formed adjacent the light port 26, while the hollow shaft 
segment 48 is provided with a centering slot or key way 64 which traverses 
the length of the head member 50. In this manner, the shaft member 48 may 
be fully inserted into the light port 26 only when the centering pin 62 
engages the receptical aperture 63 and a key (not shown) engages the 
centering slot 64. In this condition, each of the beveled surfaces 60 is 
positioned parallel to a plane containing the open end of an adjacent 
reflector 24. The bevelled surfaces 60 and the end of their corresponding 
bundle end segments 42a and 42b are preferably optically polished to allow 
maximum light transmission into the main fiber bundle 42. It will be 
readily understood by the reader that although shaft member 48 is securely 
held in the light port 26, it may be easily detached for replacement of 
the light cable 12. 
The light box 10 and light cable 12 may be employed to illuminate an 
imaging tool such as a video endoscope during a medical diagnosis or 
surgical operation. During such a procedure, only one of the two lamps is 
illuminated. Thus one of the advantages of the present invention is that 
in the event the operating lamp burns out, the second lamp may be quickly 
illuminated so that the image provided by the endoscope can be maintained 
without having to change a lamp and interrupt the surgery. An additional 
advantage of the present light box and cable assembly is achieved by 
providing the light box 10 with circuitry allowing both lamps 20 to 
operate simultaneously. In this manner, when a respective imaging tool is 
operating with one lamp 20 illuminated, the second lamp 20 may be 
activated on demand to effectively double the light intensity output 
directed at the proximal end 36, and thus the distal end 38, of the cable 
12. 
While this invention has been described in detail with reference to a 
certain preferred embodiment, it should be appreciated that the present 
invention is not limited to that precise embodiment. For example, more 
than two fiber ends and/or corresponding lamps may be employed. In 
addition, it is currently contemplated that the switching between the 
lamps may be done either manually or electrically by use of control 
circuitry incorporated in the light box. Furthermore, it would readily be 
apparent to one skilled in the art to employ light vanes, aperture wheels, 
or electronic circuitry to variably control the output light intensity of 
one or both of the lamps. Moreover, lamps of different power could be used 
so that the light intensity used is switchable between lower, higher, and 
even very high (both lamps lit at once) settings. 
Thus, in view of the present disclosure which describes the current best 
mode for practicing the invention, many modifications and variations would 
present themselves to those of skill in the art without departing from the 
scope and spirit of this invention, as defined in the following claims.