Endoscope including an improved lighting apparatus

An endoscope provided with a lighting apparatus. In this lighting apparatus, a tapered fiber is applied between a lamp and a base end face of a light guide. This taper fiber is in a tapered configuration which gradually diminishes in diameter toward an end side. The lamp is a high luminance lamp of a low outgoing angle. The lamp, a battery, and the tapered fiber of the lighting apparatus are arranged unitedly on a grip portion of the endoscope.

BACKGROUND OF THE INVENTION 
1. Field of the Invention This invention relates to an endoscope. 
2. Description of the Related Art 
Various kinds of endoscopes have been conventionally used for medical 
examination and medical treatment. However, in these conventional 
endoscopes, an endoscope main body and a lighting apparatus for providing 
light into its light guide are formed separately. The endoscope main body 
and the lighting apparatus are connected through a cord having a light 
guide, and the endoscope main body has been operated (used) with said 
lighting apparatus placed separately. 
A conventional lighting apparatus is provided with a lamp of several tens 
or several hundreds watts (W), and is heavy and large, which causes 
inconvenience in carrying the lighting apparatus. 
In some conventional lighting apparatuses, a battery is used for 
convenience in carrying, but coupling efficiency between the lamp and the 
light guide inside the endoscope, i.e. proportion (percentage) of quantity 
of light which is effectively incident on the light guide among a total 
luminescence luminous flux of the lamp, is only one percent at most, and 
this illuminance is insufficient for actual use. It is necessary to use a 
light source of a big power in order to obtain sufficient illuminance, and 
consequently, it is necessary to store the power supply system separately 
in a pocket and use a cooling fan. 
In conventional endoscopes, a lighting apparatus is large and heavy, and is 
separated from a main body of the endoscope. This causes inconvenience in 
conveying the endoscope, and a large amount of power consumption is 
required. When a battery is used for the lighting apparatus as described 
above, the endoscope is also inconvenient because the illuminance is 
insufficient or it is necessary to store the power supply system 
separately in a pocket. 
It is therefore an object of the present invention to provide an endoscope 
wherein the endoscope is easily handled and operated, it is possible to 
carry the endoscope, and it is possible to insert the endoscope into a 
human body more easily, swiftly, accurately, and safely in medical 
examination or medical treatment. 
It is another object of the present invention to provide an endoscope 
wherein the power consumption is diminished, usage for long hours is 
possible, and sufficient illuminance is obtained.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Preferred embodiments of the present invention will now be described with 
reference to the accompanying drawings. 
An endoscope shown in FIG. 4 to FIG. 6 possesses a grip portion 9 which can 
be held with one hand and an insertion portion 21 extending forward from 
the grip portion 9. The grip portion 9 possesses an eyepiece portion 15 at 
its base end and a freely oscillating distal bending controlling portion 
16 at its middle portion. 
A lighting apparatus 8 is unitedly arranged on the grip portion 9. That is 
to say, the lighting apparatus 8 is directly (without a cord having a 
light guide) attached to a rigid protruding branch portion 9a. 
The insertion portion 21 has appropriate flexibility and rigidity against 
pressure, and is provided with a distal portion 22 to be bent at its end 
which freely advances and curves as shown with an arrow A in FIG. 4. In 
the inserting portion 21, an image guide, a light guide 3 (see FIG. 6), a 
wire 17 for bending distal portion (see FIG. 6), and a tube for working 
channel are inserted inside an outermost protecting tube (which outer 
diameter is arranged to be, for example, at least 5 mm). In FIG. 5, 23 
indicates a working channel connection portion. 
The controlling portion 16 in a L-shaped or U-shaped configuration is fixed 
at a rotational axis 24. It is possible to rotate a wire reel 18 through a 
reduction gear 25 by oscillating the controlling portion 16, thereby the 
distal portion 22 to be bent at the end of the insertion portion 21 can be 
oscillated. 
As shown in FIG. 6 and FIG. 7, it is arranged so that a part (or the whole) 
of the lighting apparatus 8 is detachable from the grip portion 9. The 
lighting apparatus 8 is provided with a lamp 2, a battery 1 (as a power 
source), and a tapered fiber 4 having a tapered configuration which 
diameter diminishes toward the end side. In this case, the lighting 
apparatus 8 protrudes from the grip portion 9 toward a direction that 
intersects perpendicularly with an axis of the grip portion 9. It is 
possible to arrange the lighting apparatus 8 to intersect the axis of the 
grip portion 9 at an angle besides 90.degree.. 
In the illustration in FIG. 6 and FIG. 7, the tapered fiber 4 is fixed 
inside the branch portion 9a which protrudes from the grip portion 9, and 
an incident end 4a having a big diameter appears outside under a detached 
situation shown in FIG. 7. A male screw portion 27 is formed on an outer 
circumference of the end of the branch portion 9a, parts in the lighting 
apparatus 8 excluding the tapered fiber are stored in a casing 20, a cap 
nut 19 is arranged on an end of a protruding cylindrical portion 28, and 
the cap nut 19 fits unitedly and detachably with the male screw portion 
27. 
In order to arrange the lighting apparatus 8 unitedly on the grip portion 9 
as shown in FIG. 4 to FIG. 7 for actual use as an endoscope, it is 
indispensable to diminish this lighting apparatus in size and weight and 
arrange an effective quantity of light to be incident from a base end face 
of the light guide 3, therefore the lighting apparatus 8 is composed as 
described below in the present invention. 
That is to say, in FIG. 1 and FIG. 2, the lamp 2 as the light source is a 
(highly convergent) high luminance lamp of a low outgoing angle. A lamp as 
shown in FIG. 2, wherein a proportion of the light elements which outgoing 
angles 2.theta..sub.1 are at most 20.degree. is at least half of the 
forward total quantity of light, is herein described as "a high luminance 
lamp of a low outgoing angle". The lamp 2 can be a lamp of any kind and 
any structure provided these conditions are satisfied, for example, a 
halogen lamp having a lens structure unitedly on an end portion of a lamp 
glass bulb. 
It is preferable to use a lithium battery as the battery 1 and utilize its 
advantage of being small sized and long-life. It is also possible to use a 
nickel-cadmium battery, a primary electrical cell, or a secondary battery. 
The tapered fiber 4 is applied between the lamp 2 and the base end face 3a 
of the light guide 3. The tapered fiber 4 is used to guide the outgoing 
light to the end with low-loss and increasing light density toward the 
light guide 3, and gradually diminishes in diameter toward the end side. 
It is possible to use a halogen lamp as the lamp 2, and a halogen lamp 
with an end lens of approximately 1 W to 10 W is suitable. 
This tapered fiber 4 is produced by (heating and) lengthening a 
multicomponent glass fiber preform, and is arranged to be at least 0.4 in 
characteristic numerical aperture NA.sub.0. 
In other words, it is arranged so that NA.sub.0 .gtoreq.0.4. 
In FIG. 1, 5 indicates a part of a light guide plug. The tapered fiber 4 is 
inserted into a base end side hole portion 6a of an axis hole 6 of the 
light guide plug 5 and fixed with adhesive, and an outgoing end 4b at an 
end of the tapered fiber 4 is inserted into a middle small diameter hole 
portion 6b of the axis hole 6. 7 is a cover of the light guide 3, and a 
base end portion of the cover 7 is inserted into an end side hole portion 
6c of the light guide plug 5, a base end face of the light guide 3 which 
slightly appears and protrudes from the base end face of the cover 7 is 
inserted into the middle small diameter hole portion 6b and placed to face 
with the outgoing end 4b of the tapered fiber 4 closely or with a minute 
space. 
FIG. 2 and FIG. 3 are enlarged and simplified explanatory views 
illustrating a principal portion of FIG. 1 or FIG. 6, and as shown in FIG. 
2 and FIG. 3, indicating an outer diameter of the incident end 4a (having 
a big diameter) of the tapered fiber 4 as D.sub.1, a numerical aperture of 
the incidence as NA.sub.1, an outer diameter of the outgoing end 4b as 
D.sub.2, a numerical aperture of the outgoing as NA.sub.2, an outer 
diameter of the light guide 3 as D.sub.0, and (as described above,) a 
characteristic numerical aperture of the tapered fiber 4 (which is 
determined by a refractive index between the core and the clad) as 
NA.sub.0, dimensions and characteristics of each portion are arranged 
satisfying the following numerical formula (1), numerical formula (2), and 
numerical formula (3). 
EQU 0.9.ltoreq.D.sub.2 /D.sub.0 .ltoreq.1.5 (1) 
EQU 1.1.gtoreq.(D.sub.1 .multidot.NA.sub.1)/(D.sub.2 
.multidot.NA.sub.2).gtoreq.0.7 (2) 
EQU NA.sub.2 .ltoreq.1.1.multidot.NA.sub.0 (3) 
In the foregoing numerical formula (1), when the value is less than 0.9, 
the diameter of the outgoing end 4b of the tapered fiber 4 becomes 
extremely small in comparison with the diameter of the light guide base 
end face 3a, and a large portion in a section of the light guide 3 is not 
utilized effectively. On the contrary, when the value is over 1.5, a large 
portion of the light quantity ejected from the outgoing end 4b of the 
tapered fiber 4 becomes wasteful (is not effectively transmitted into the 
light guide 3). 
In the numerical formula (2), when the value is less than 0.7, the ability 
of the tapered fiber 4 to increase light density is not utilized 
effectively, which causes ineffectiveness. On the contrary, when the value 
is over 1.1, the amount of energy of light which leaks from the tapered 
fiber 4 becomes large, which causes generation of heat. 
When the value does not satisfy the numerical formula (3), generation of 
heat occurs as well as when the value does not satisfy the numerical 
formula (2). 
The battery 1 is used as the power source, the lithium battery is light, 
small, and has a long life, and the output voltage and current are stable, 
and these are advantages of the present invention. It is preferable to use 
a lithium battery of at most 10 V. The lamp 2 is a high luminance lamp of 
a low outgoing angle, and a halogen lamp with an end lens of approximately 
1 W to 10 W (more preferably not exceeding 5 W) is suitable. A cordless 
endoscope composed as shown in FIG. 4 to FIG. 7 is arranged so that the 
endoscope can be easily carried, enlarges range of the operator to act and 
use the endoscope, and is convenient for diagnosis and medical treatment. 
Provided a part or the whole of the lighting apparatus 8 is arranged to be 
detachable, it is possible to disassemble the endoscope and store it 
easily in a bag or a case when carrying the endoscope. In this case, the 
casing 20 where the battery 1 and the lamp 2 are stored is also 
detachable, therefore it is possible to detach the casing 20 and connect 
the endoscope to a stationary type lamp through an extension light guide 
cord and conduct stabilized observation. 
FIG. 8A and FIG. 8B show another embodiment of the present invention, and 
it is possible to change the endoscope from attached (connected) situation 
as shown in FIG. 8A to a detached (separated) situation as shown in FIG. 
8B. In this case, a tapered fiber 4 is arranged at a casing (a lamp case) 
20 side and is detached from a branch portion 9a of a grip portion 9 
unitedly with a lamp 2 and a battery 1. A base end of the light guide 3 is 
arranged at an end of the branch portion 9a, and detachment is made 
through, for example, a cap nut 19. Described below is an experimental 
example. 
A halogen lamp of 2.5 V and 1.7 W with characteristics shown in Table 1 was 
used as the lamp 2. 
TABLE 1 
______________________________________ 
Items Measurement 
______________________________________ 
L (distance from the lamp; mm) 
0 10 20 40 100 
Forward Illuminance (.times.10.sup.4 ; 1x) 
15 7.3 5.3 2.4 0.4 
Divergent Angle 7 14 17 28 
NA 0.06 0.12 0.17 0.24 
______________________________________ 
In this experiment, the tapered fiber 4 is, with the core and the clad made 
of multicomponent glass, 0.62 in characteristic numerical aperture 
NA.sub.0, 3.6 mm in incident end diameter D.sub.1, 1.28 mm in outgoing end 
diameter, and 38 mm in length L. Nineteen plastic fibers each of which is 
0.5 in numerical aperture NA and 250 microns in outer diameter were used 
as the light guide 3. A lithium battery of 3 V was used as the battery 1. 
Table 2 shows results of measuring illuminance under the foregoing 
conditions. 
TABLE 2 
______________________________________ 
Lighting Illuminance (1x) 
Time Distance from the Light Guide (mm) 
(min.) 0 mm 20 mm 40 mm 
______________________________________ 
0 41,000 5,500 1,250 
10 41,000 5,400 1,400 
20 40,000 5,400 1,350 
30 40,000 5,300 1,300 
______________________________________ 
From Table 1 and Table 2, coupling efficiency B of the lighting apparatus 8 
and the light guide 3 becomes extremely high as shown in the following 
numerical formula (4). 
##EQU1## 
The following is a measurement result of using a conventional example for 
comparison wherein a metal-halide lamp of 200 W was used as the light 
source. In this case, the total amount of luminescence luminous flux was 
250 Im, and when a light guide composed by seven plastic fibers of 250 
microns (directly) received the luminescence luminous flux, in case the 
outer diameter of the light guide is 0.75 mm and the lighting area is 0.2 
mm.sup.2 (distance: 5 mm), the quantity of light becomes 4 Im 
(Ix/m.sup.2), and the coupling efficiency B is extremely low as shown in 
the following numerical formula (5). 
##EQU2## 
It is also preferable to use the endoscope of the present invention as a 
fiber scope for use in industrial application which is small, light, and 
handy to carry. 
According to the present invention, the endoscope is easily handled and 
operated, and it is possible to carry the endoscope. Moreover, it is 
possible to insert the endoscope into a human body more easily, swiftly, 
accurately, and safely in medical examination or medical treatment. The 
endoscope is arranged to be small and light, and is handy to carry. 
Especially it is needless to store the battery 1 and the lamp 2 in the 
grip portion 9, therefore the grip portion 9 can be diminished in 
diameter, and this increases usability. It is possible to send 
approximately 5 to 10 percent of the forward total amount of luminous flux 
toward the light guide 3, the coupling efficiency is extremely improved, 
the power consumption is diminished, usage for long hours is possible, and 
sufficient illuminance is obtained. The light guide plug 5 connects the 
light guide 3 and the tapered fiber 4 with stability, and light of the 
light source lamp is effectively transmitted to the light guide. It is 
possible to connect this endoscope to a stationary type lamp through an 
extension light guide cord, therefore it is possible to obtain sufficient 
illuminance for hours and conduct stable observation using this endoscope. 
While preferred embodiments of the present invention have been described in 
this specification, it is to be understood that the invention is 
illustrative and not restrictive, because various changes are possible 
within the spirit and indispensable features.