Structure of end portion of side-looking type electronic endoscope

A structure of the end portion of a side-looking type electronic endoscope in which an irradiation window is disposed closer to the end than an observation window, thereby enabling a better observation of a deceased part at the time of treatment. The structure also facilitates the removal of a light guide. The observation window is disposed on the side surface of the endoscope, and a solid-state image sensor is attached to the observation window via the objective system member and the rectangular prism. A light guide is disposed in the space formed on the back side of the prism; and an irradiation window which is connected to the light guide is disposed closer to the end of the end portion than the observation window. It is therefore possible to observe the internal body as an object of inspection with the light irradiated from the portion closer to the end than the observation window. By providing a tool engaging portion which engages with a toll for removing the light guide at the end portion of the light guide, the removal of the light guide at the time of repair or replacement is facilitated.

BACKGROUND OF THE INVENTION 
This application claims the priority of Japanese Patent Application Nos. 
6-232021 and 6-232020 filed on Sep. 1, 1994. 
1. Field of the Invention 
The present invention relates to a structure of the end portion of a 
side-looking type electronic endoscope which is provided with an 
irradiation window, an observation window and a forceps insertion hole 
arranged on the side surface thereof. 
2. Description of the Related Art 
FIGS. 9 and 10 show the structure of the end portion of a conventional 
side-looking type electronic endoscope. An observation window 2 and an 
irradiation window 3 are arranged on the side surface of the end portion 1 
of the endoscope. A CCD (Charge Coupled Device) 5 is attached to the 
observation window 2 via an optical system member 4, and a signal cable 7 
is connected to the printed circuit board 6 of the CCD 5. The signal cable 
7 is led to, for example, an external processor apparatus. A light guide 8 
is attached to the irradiation window 3. The light guide 8 is finally 
connected to a light source device. A raising table 10 connected to a wire 
9 and supported by a shaft 11 is disposed in parallel with the observation 
window 2, as shown in FIG. 10, and a forceps insertion hole is provided 
behind the raising table 10. By raising the raising table 10 by pulling 
the wire 9, it is possible to lead a manipulating tool 12 from the side 
surface (through the forceps insertion hole) up to a predetermined 
position or in a predetermined direction, as shown in FIG. 9. 
According to this structure of the end portion 1, the light supplied 
through the light guide 8 is projected into the body as the object of 
inspection through the irradiation window 3, and the image of the internal 
body is caught by the CCD 5 via the observation window 2 and the optical 
system member 4. The picture signals obtained by the CCD 5 are input to 
the external processor device or the like through the signal cable 7 and 
processed by the external processor device. As a result, the image of the 
internal body is displayed on a monitor. At the same time, it is possible 
to lead the manipulating tool 12 from the side surface of the end portion 
1 so as to execute various treatments. 
In a conventional side-looking type electronic endoscope, since the 
observation window 2 is disposed closer to the end than the irradiation 
window 3, there is a problem that a shadow is cast on the surface (an 
inclined surface or the like) of a protruding or recessed portion within 
the body which faces in the direction of insertion of the endoscope, or 
that the surface is shaded. For example, in the case of the mammilation of 
the duodenum, which is a representative part treated by an endoscope, the 
endoscope 14 is inserted into the duodenum 16 through the stomach 15, so 
as to conduct a predetermined treatment on the mammilation 19 having an 
opening portion which opens into the bile duct 17 and the ductus 
pancreaticus 18, as shown in FIG. 11. However, since the mammilation 19 is 
a protruding portion, as shown in FIG. 11, when light is projected from 
the irradiation window 3 disposed at the rear portion, the opening portion 
of the mammilation 19 is shaded, and it is difficult to treat the opening 
portion with the manipulating tool 12. 
The same problem is produced in the observation of a diverticulum. In many 
cases, it is more convenient to dispose the irradiation window 3 closer to 
the end than the observation window 2. In order to dispose the irradiation 
window 3 closer to the end than the observation window 2, it is also 
necessary to dispose the light guide 8 in the vicinity of the end, which 
inconveniently increases the diameter of the endoscope. That is, as is 
clear from FIG. 10, since the optical system member 4, the CCD 5, the 
printed circuit board 6, the signal cable, 7, etc. are connected to the 
observation window 2, there is no place to dispose the light guide 8 in 
the state shown in FIG. 10, so that it is necessary to increase the 
diameter of the endoscope. However, an endoscope is required to have as 
small a diameter as possible in order to alleviate the pain of a patient. 
In addition, in a conventional endoscope, when the printed circuit board or 
the like as well as the CCD is replaced, it is sometimes necessary to 
remove the light guide depending upon the structure of the end portion. 
However, since the endoscope adopts an airtight structure, the light guide 
is tightly adhered to the supporting portion with an adhesive or the like. 
It takes much time to remove the light guide, and the light guide itself 
is sometimes broken. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the present invention to eliminate the 
above-described problems in the related art and to provide a structure of 
the end portion of a side-looking type electronic endoscope in which an 
irradiation window is disposed closer to the end than an observation 
window without increasing the diameter of the endoscope, thereby enabling 
a better observation of a deceased part at the time of treatment. 
It is another object of the present invention to provide a structure of the 
end portion of a side-looking type electronic endoscope which enables a 
light guide to be removed easily and in a short time and which can prevent 
a breakage of the light guide itself. 
To achieve these ends, in one aspect of the present invention, there is 
provided a structure of the end portion of a side-looking type electronic 
endoscope comprising: an observation window disposed on the side surface 
of the endoscope; an objective system member connected to the observation 
window; a prism (rectangular prism) for reflecting incident light which 
passes the objective system member at an approximately right angle so as 
to emit the light to the side surface of the endoscope; a solid-state 
image sensor attached to the observation window via the prism so as to 
pick up an image of the internal body as an object of inspection; a light 
guide disposed closer to the end of the end portion by utilizing the space 
formed on the back side of the prism; and an irradiation window which is 
connected to the light guide and disposed closer to the end than the 
observation window. 
According to this structure, the solid-state image sensor, the printed 
circuit board and the like which are disposed at a position on which 
incident light directly impinges in a conventional structure are rotated 
at 90 degrees around the prism, so that a space is formed on the back side 
of the prism. By utilizing this space on the back side of the prism, the 
light guide is disposed between the back surface of the prism and the case 
body of the endoscope. By optically connecting the irradiation window to 
the light guide, it is possible to dispose the irradiation window closer 
to the end of the endoscope than the observation window. 
In a structure of the end portion of a side-looking type electronic 
endoscope provided in another aspect of the present invention, a tool 
engaging member with which a removing tool engages is provided on the 
outer periphery of the end portion of the light guide so as to remove the 
light guide disposed at the end of the endoscope. This structure 
facilitates the removal of the light guide. It is possible to fix the 
light guide to the vicinity of the observation window by a screw. 
A projecting portion as the tool engaging portion may be formed as the tool 
engaging member on a cylindrical body placed over the outer peripheral 
portion of the light guide. The tool engaging member may be provided with 
an engaging hole for receiving a hook-shaped tool. 
The above and other objects, features and advantages of the present 
invention will become clear from the following description of the 
preferred embodiments thereof, taken in conjunction with the accompanying 
drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
First embodiment 
FIGS. 1 to 3 show the structure of the end portion of a first embodiment of 
a side-looking type electronic endoscope according to the present 
invention. An end portion 21 of the endoscope is connected to an angle 
portion 22. An observation window 23 is formed on the top side surface of 
the end portion 21, and a prism (rectangular prism) 25 is connected to the 
observation window 23 via an objective system 24. The prism 25 is disposed 
in such a manner as to reflect incident light 100 at 90 degrees and emit 
it toward the side surface, as shown in FIG. 2. A CCD 26 having a cover 
glass and a printed circuit board 27 are attached to the prism 25. In this 
case, the CCD 26 and the printed circuit board 27 are therefore disposed 
at a right angle to the side surface on which the observation window 23 
and the like are disposed (rotated at 90 degrees around the observation 
window 23), and the pickup surface of the CCD 26 is parallel to the 
optical axis of the objective system 24. 
At this time, a space S is formed on the back side of the prism 25, as 
shown in FIG. 2. In this embodiment, a light guide (a bundle of optical 
fibers) 30 is disposed at the bottom side between the back diagonal 
surface of the prism 25 and a bottom surface of said end portion and a cap 
29 by utilizing this space S. An irradiation window 31 is disposed closer 
to the end than the observation window 23, and the light guide 30 is 
connected to the irradiation window 31, as shown in FIG. 1. By utilizing 
the observation window 23 and the irradiation window 31 which is disposed 
closer to the end than the observation window 23, it is possible to 
closely observe the surface (inclined surface, etc.) of a protruding or 
recessed portion within the body which faces in the direction of insertion 
of the endoscope. In this embodiment, a light shielding agent is applied 
to the outer periphery of the light guide 30 (or the light guide is 
accommodated in a light shielding pipe), and a light shielding agent is 
also applied to the outer peripheries of the prism 25 and the CCD 26 so as 
to exclude the influence of other light on the observation window 23 and 
the irradiation window 31. 
A forceps insertion hole 33 which communicates with a manipulating tool 
channel is formed in the side surface of the end portion 21, and a raising 
table 34 is attached to the end of the forceps insertion hole 33, as shown 
in FIG. 3. The raising table 34 is supported by a shaft 35 (FIG. 2), and a 
wire 36 is attached to the raising table 34. When the wire 36 is pulled, 
the raising table 34 is raised so as to enable a manipulating tool 12 to 
be led out of the side surface of the end portion 21 in the perpendicular 
direction. A cap 38 is placed over the end portion 21, a nozzle 40 
connected to an air/water supply pipe is disposed in the vicinity of the 
observation window 23, and wires 41A, 41B for bending the angle portion 23 
are provided at the rear portion of the end potion 21, as shown in FIG. 1. 
FIG. 4 shows the first embodiment having the above-described structure 
which is applied to the mammilation of a duodenum. In the end portion 21 
of the endoscope 14 which is inserted from the stomach 15 to the duodenum 
16, since irradiating light is emitted from the irradiation window 31 
which is disposed closer to the end than the observation window 23, it is 
possible to clearly irradiate the opening portion which opens into the 
bile duct 17 and the ductus pancreaticus 18 on the back side of the 
mammilation 21. It is therefore easy to treat the diseased part with the 
manipulating tool 12 while observing the image of the mammilation 21 which 
is obtained through the observation window 23. 
In the first embodiment, since the prism 25 is used, the CCD 26 and the 
printed circuit board 27 are disposed on the side surface of the prism 25 
in parallel to the optical axis, and the light guide 30 is disposed in the 
space S on the back side of the prism 25 adjacent to bottom surface, it is 
possible to dispose the light guide 30 and the irradiation window 31 
closer to the end than the observation window 23 without the need for 
increasing the diameter of the end portion 21. As a result, it is easy to 
observe the surface of a protruding or recessed portion within the body 
which faces in the direction of insertion of the endoscope 14 by the 
irradiation of light through the irradiation window 31, which 
advantageously enables a good treatment of, for example, the mammilation 
21 of the duodenum 16. 
Second embodiment 
FIGS. 5 and 6 show the structure of the end portion of a second embodiment 
of a side-looking type electronic endoscope according to the present 
invention. An observation window 62 is formed on the side surface of the 
end portion 60, and a CCD 65 is connected to the observation window 62 via 
an objective system 63 and a prism 64 (FIG. 6). A printed circuit board 66 
is attached to the CCD 65. On the opposite side surface to the side 
surface on which the optical observing system members are provided, a 
raising table 68 to which a wire 67 is connected is provided, as shown in 
FIG. 6, and a forceps insertion hole for leading out a manipulating tool 
69 is disposed on the back side of the raising table 68. A cap 72 fixed by 
a fixing screw 71 is placed over the end portion 50, and a nozzle 74 
connected to an air/water supply pipe 73 is provided in the vicinity of 
the observation window 62, as shown in FIG. 5. 
An irradiation window 76 is provided in approximately parallel with the 
observation window 62, and a light guide 77 consisting of a bundle of 
optical fibers is attached to the irradiation window 76. The outer 
periphery of the light guide 77 is covered with a protective pipe or a 
light shielding pipe. The light guide 77 is fixed to a supporting portion 
79 by a predetermined set screw, and at the time of fixing the light guide 
77, a sealing agent is poured so as to keep the airtightness. In this 
embodiment, by attaching the light guide 77 to the supporting portion 79 
by using the set screw 78, it is possible to dispense with a conventional 
adhesive or to reduce the amount of adhesive used to a small one, which 
facilitates the removal of the light guide 77. 
In the second embodiment, the light guide 77 is provided with a cylindrical 
body 81 having a small strip-like protruding portion 80 as an engaging 
member. The cylindrical body 81 is formed by bending a single sheet in 
such a manner as to leave the protruding portion 80. It is possible to 
engage a tool for removing the light guide 77 with the the protruding 
portion 80. In this case, the protruding portion is clamped by pliers or 
cutting pliers. 
According to the second embodiment of a side-looking type electronic 
endoscope having the above-described structure, when the CCD 65, the 
printed circuit board 66 or the like is replaced, or the light guide 77 
itself is replaced, the cap 72 is first removed, and the set screw 78 is 
then removed. Thereafter, the protruding portion 80 is clamped and pulled 
by a tool such as pliers and cutting pliers. In this manner, it is 
possible to remove the light guide 77 easily and in a short time. 
In the present invention, since the irradiation window 76 is disposed 
closer to the end than the observation window 62 and the light guide is 
disposed in the space S on the back side of the prism 64, it is necessary 
to remove the light guide 77 when the printed circuit board 66 or the like 
is removed. According to the second embodiment, replacement of the printed 
circuit board 66 or the like is facilitated. 
In the light guide 77 in a conventional endoscope, a bundle of optical 
fibers are disposed with the end portions bound in a bundle because it is 
necessary to reduce the diameter of the end portion 60. When a protective 
pipe or the like is provided, the pipe is made thinner at the end portion 
60. As a result, when the light guide 77 is removed with a tool or the 
like, the light guide 77 itself is sometimes broken. In addition, when the 
light guide 77 is broken in the middle, a part of it is sometimes left in 
the hole of the supporting portion 79 for receiving the light guide 77. In 
such a case, since the light guide 77 is firmly adhered to the supporting 
portion 60 in a conventional structure, it is necessary to break the 
irradiation window 76, which costs much. 
In the second embodiment, however, since the cylindrical body 81 having the 
protruding portion 80 is provided and the light guide is fixed by the set 
screw 78, the possibility of a breakage of the light guide 77 itself is 
reduced. 
Third embodiment 
FIGS. 7 and 8 show the structure of the end portion of a third embodiment 
of a side-looking type electronic endoscope according to the present 
invention. The arrangement of a light guide 83 and the main structure of 
the other portion are the same as in the second embodiment. In the third 
embodiment, a cylindrical body 85 having a protruding portion 84 is 
provided at the end of the light guide 83 as an engaging member. The 
cylindrical portion at the end portion is fixed to the light guide 83, and 
the protruding portion 84 is formed by cutting off about 3/4 of the width 
cylinder via a middle portion formed by cutting off about more than 1/2 of 
the width of the cylinder. An engaging hole 86 is formed in the protruding 
portion 34, as shown in FIG. 8 (A). 
According to the third embodiment, the light guide 83 is easily removed 
from the supporting portion 79 by clamping and pulling the protruding 
portion with a tool or by engaging a hook-shaped tool with the engaging 
hole 86 and pulling the light guide 83 after the cap 72 and the set screw 
78 are removed. Breakage of the optical fibers is therefore prevented and 
it is not necessary to break the irradiation window 76. 
While there has been described what are at present considered to be 
preferred embodiments of the invention, it will be understood that various 
modifications may be made thereto, and it is intended that the appended 
claims cover all such modifications as fall within the true spirit and 
scope of the invention.