Endoscope angling mechanism

An endoscope angling mechanism which is provided with: an angle operating means including a pair of first and second operating wires to be pulled to and fro for arcuately bending an angle portion of joint ring structure at the distal end of an insert section extending contiguously from an operating section of an endsoscope, the first operating wire having the fore end thereof securely stopped on an angle ring in the foremost position in the angle portion or to a rigid portion at the distal end of the angle portion and the second operating wire having the fore end thereof securely stopped on an angle ring in a position posterior to and spaced from the foremost angle ring by a predetermined number of angle rings; and a restraining means for restraining forward movement of the second operating wire in angling operation until operated with a predetermined increased force.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to an endoscope angling mechanism for bending a 
rigid portion at the tip end of an insert section of an endoscope 
arcuately into desired directions. 
2. Description of the Prior Art 
Endoscopes are in wide use for medical and industrial purposes, for 
example, for internal examination or diagnosis of patients' bodies, 
engines, nuclear reactors or other equipments, or for therapeutic or 
repairing treatments with use of concurrently inserted forceps or other 
instruments. 
For understanding the status of the prior art, FIGS. 7 and 8 schematically 
illustrate the general construction of an endoscope of this sort and the 
construction of a prior art angling mechanism, respectively. In these 
figures, indicated at 1 is an insert section and at 2 is an operating 
section of the endoscope. The insert section 1 is successively composed 
of: a flexible portion 1a which forms a major part of the insert section 1 
in proportion, extending contiguously from the operating section 2 of the 
endoscope and being smoothly flexible in conformity with the shape of the 
path of insertion of the endoscope; an angle portion 1b connected to the 
fore end of the flexible portion 1a; and a rigid tip end portion 1c 
connected to the fore end of the angle portion 1b. 
In this instance, the angle portion 1b has a joint ring structure which is 
composed of a plural number of pivotally connected angle rings 3 and which 
can be bent in a desired direction. Namely, the rigid portion 1c at the 
distal end can be turned into a desired direction when introducing the 
insert section 1 into a body along a path of insertion or when changing 
the field of view of observation. For bending the angle portion 1b in this 
manner, an angling mechanism is provided in association with a knob 
section to be manipulated by the operator. 
As shown in FIG. 8, the angling mechanism of this sort usually employs a 
pair of upper and lower operating wires 4a and 4b (or a pair of upper and 
lower wires plus a pair of left and right wires) within the angle rings 3 
in the angle portion 1b. Each of these operating wires 4a and 4b has the 
fore end thereof securely stopped on an angle ring 3a in the foremost 
position (or to the distal end of the rigid portion 1c), and the other end 
extended into the operating section 2 and wound on an angle drum 5. The 
angle drum 5 is mounted on a rotational shaft 6 which is led out of the 
housing of the operating section 2 and coupled with an angle knob 7. 
Accordingly, as the angle knob 7 is turned by an operator, the operating 
wires 4a and 4b are pulled to and fro to bend the angle portion 1b as 
indicated by imaginary line in FIG. 7. 
However, in a case where the angle portion 1b is arranged to be bent in its 
entirety by the angling operation as described above, difficulties are 
encountered, for example, in changing the field of view of observation in 
a narrow intracorporeal cavity or the like. For the purpose of overcoming 
such a problem, there has been developed an endoscope with an angle 
portion 1b which has a higher rigidity toward its base end in such a way 
that it is bendable only in its fore end portion in an initial stage of 
the angling operation and becomes bendable toward the rigid base end 
portion and finally in its entire body in proportion to the magnitude of 
the applied angling efforts. This angle construction has a problem that 
the load of the angling operation is increased to such an extent as to 
impair smooth operation of the angle knob. 
SUMMARY OF THE INVENTION 
The present invention contemplates to overcome the above-mentioned problems 
or drawbacks, and has as its object the provision of an endoscope angling 
mechanism which can improve the operationability of the angle portion of 
an endoscope. 
It is another object of the present invention to provide an endoscope 
angling mechanism which can bend only the fore end portion of the angle 
portion, if necessary, smoothly in a facilitated manner. 
It is still another object of the invention to provide an endoscope angling 
mechanism which can change the field of view of observation easily even in 
a narrow space like an intracorporeal cavity. 
In accordance with the present invention, the above-stated objectives are 
achieved by an endoscope angling mechanism which is provided with: an 
angle operating means including a pair of first and second operating wires 
to be pulled to and fro for arcuately bending an angle portion of joint 
ring structure at the distal end of an insert section extending 
contiguously from an operating section of an endoscope, the first 
operating wire having the fore end thereof securely stopped on an angle 
ring in the foremost position in the angle portion or to a rigid portion 
at the distal end of the angle portion and the second operating wire 
having the fore end thereof securely stopped on an angle ring in a 
position posterior to and spaced from the foremost angle ring by a 
predetermined number of angle rings; and a restraining means for 
restraining forward movement of the second operating wire in angling 
operation until operated with a predetermined increased force. 
The above and other objects, features and advantages of the invention will 
become apparent from the following description and the appended claims, 
taken in conjunction with the accompanying drawings showing by way of 
example preferred embodiments of the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS 
Hereafter, the invention is described more particularly by way of the 
preferred embodiments shown in the drawings. 
Referring first to FIGS. 1 through 4, there is shown a first embodiment of 
the invention, in which indicated at 10 is an insert section and at 11 is 
an operating section of an endoscope. The references 10a, 10b and 10c 
denote a flexible portion, an angle portion and a rigid tip end portion of 
the insert section 10, respectively. 
The angle portion 10b has a joint ring structure which is composed of a 
plural number of flexibly connected angle rings 12. A pair of operating 
wires 13a and 13b are inserted in the angle portion along the inner 
surface thereof, such that the angle portion 10b is bent upward or 
downward in FIG. 1 by pulling one of the operating wires in the rearward 
direction and the other wire in the forward direction. The rear ends of 
these operating wires 13a and 13b are stopped on an angle drum in the same 
manner as in the prior art angling mechanism mentioned hereinbefore. 
The fore end of one of these operating wires 13a and 13b, for example, of 
the first operating wire 13a is securely stopped on an angle ring 12a in 
the foremost position in the angle portion 10b, while the fore end of the 
other or the second operating wire 13b is securely stopped on an angle 
ring 12d which is located in a position posterior to and spaced from the 
foremost ring 12a by a predetermined number of angle rings, more 
specifically, to an angle ring 12d in the fourth position in this 
particular embodiment. 
Further, the second operating wire 13b is provided with a bulged portion 15 
within the housing of the operating section 11 for cooperating with a 
restraint means which is provided also in the housing of the operating 
section 11, including a piston cylinder 16 for restraining forward 
movement of the second operating wire 13b. Piston rod member 16a of the 
cylinder 16 is connected to a blocking plate 17 with an aperture 17a 
through which the second operating wire 13b is passed and freely movable 
except the bulged portion 15. Accordingly, the second operating wire 13b 
is freely passable through the aperture 17a when it is pulled for movement 
in the direction of arrow A in FIG. 1, but its displacement is restrained 
by abutting engagement of the bulged portion 15 against the blocking plate 
17 when it is pushed forward as indicated by arrow B in the same figure. 
In this instance, a vacuum chamber 19 is defined in the cylinder 16 by a 
piston 18 which is connected to the rod 18a. This vacuum chamber 19 is 
provided with a check valve 20 which permits outflow of air to the 
atmosphere but blocks inflow of air into the vacuum chamber 19. The 
cylinder 16 is provided with an aperture 21 in its peripheral wall, so 
that the pressure in the vacuum chamber 19 is lowered by expansion when 
the piston 18 is moved forward from a rear end end position in the 
cylinder 16, until the piston 18 clears the aperture 21. Therefore, the 
forward movement of the piston 18 is firstly met by a large resistance, 
which however drops markedly as soon as the piston 18 is moved forward 
beyond the position of the aperture 21. In order to prevent an abrupt drop 
of the resistance, the piston 18 is provided with a V-groove 22 which 
constitutes a variable orifice. Further, the blocking plate 17 is biased 
toward the rear end wall of the cylinder 16 by a return spring 23 which 
pushes back the piston 18 toward the rear end wall of the cylinder upon 
removing the pushing efforts on the second operating wire 13b. 
In this embodiment, by turning the angle drum 14 in the direction of arrow 
C in FIG. 1, the first operating wire 13a is pulled toward the angle drum 
14 while the second operating wire 13b is pushed away from the drum. At 
this time, the bulged portion 15 of the pushed second operating wire 13b 
is abutted against the marginal edges of the aperture 17a in the blocking 
plate 17 to push the latter in the direction of arrow B. As a result, the 
rod 16a is moved in the same direction together with the blocking plate 
17, accompanied by a forward movement of the piston 18 which is connected 
to the rod 16a, lowering the pressure in the vacuum chamber 19 through 
expansion and increasing the resistance to the pushing efforts on the 
second operating wire 13b to restrain its forward movement. Therefore, of 
the angle rings 12 in the angle portion 10b, the angle rings which are in 
positions rearward of the angle ring 12d, to which the fore end of the 
second operating wire 13b is connected, are retained in a rectilinear 
form while the angle rings 12 forward of the angle ring 12d are bent 
arcuately by the tension of the first operating wire 13a. Consequently, as 
shown particularly in FIG. 3, the the angle portion 10b is bent to one 
side in its fore end portion alone. This permits the operator to change 
the field of observation extremely easily and smoothly even in a narrow 
intracorporeal cavity or the like. 
Now, upon rotating the angle drum 14 further from that position, the piston 
18 is displaced further in the forward direction by the increased pushing 
efforts on the second operating wire 13b, clearing the aperture 21 in the 
peripheral wall of the cylinder 16. Whereupon, the vacuum chamber 19 is 
opened to the atmosphere and put in no-load condition, permitting the 
operator to push forward the second operating wire 13b with ease. As a 
result, as shown in FIG. 4, the entire angle portion 10b is bent arcuately 
as in an ordinary angling operation. 
Although an extra operating force is required to compress the return spring 
23 for bending the whole angle portion 10b, the angle drum 14 can be 
operated easily under a relatively light load by employing a return spring 
23 with a minimum necessary spring force for returning the piston 18 to 
the rear position when the bulged portion 15 is disengaged from the 
blocking plate 17. 
Upon communication with the atmosphere of the vacuum chamber 19 of the 
cylinder 16, the second operating wire 13b is relieved of the restraining 
action of the cylinder 16 of the restraining means, and the angle portion 
10b as a whole becomes bendable as shown in FIG. 4 in contrast to the 
restrained state where only its fore end portion is bendable as shown in 
FIG. 3. At this time, for the purpose of precluding dangerous abrupt 
bending of the angle portion 10b, the V-groove 22 which is provided on the 
piston 18 as a variable orifice prevents a sudden pressure change in the 
vacuum chamber 19 and thus ensures smooth cancellation of the restraining 
action. 
If the angle drum 14 is returned to its initial position, the blocking 
plate 17 is moved in the direction of arrow A by the action of the return 
spring 23, pushing the piston 18 back to a position in the proximity of 
the rear end of the cylinder 16. At this time, the volume of the vacuum 
chamber 19 is reduced smoothly as air in the vacuum chamber 19 is 
discharged to the atmosphere through the check valve 20. 
On the other hand, when the angle portion 10b is to be bent in the opposite 
direction, namely, when the second operating wire 13b is pulled toward the 
drum 14 while pushing forward the first operating wire 13a, the bulged 
portion 15 is moved away from the blocking plate 17 so that the whole 
angle portion 10b is bent arcuately free of any restraint force. 
Referring now to FIGS. 5 and 6, there is shown a second embodiment of the 
invention, in which the component parts identical or equivalent to the 
corresponding parts in the first embodiment are designated by similar 
reference numerals. Explanation of the identical or equivalent parts is 
omitted in the following description to avoid repetitions. 
In this embodiment, the restraining means is constituted by a lever 31 
which is engageable with one of anti-slackening sleeves 30 of the first 
and second operating wires 13a and 13b. The lever 31 is formed with a slit 
32 for passing the second operating wire 13b therethrough. More 
specifically, as shown in FIG. 6, the slit 32 is provided with a broad 
slit portion 32a for passing the sleeve 30 and a narrow slit portion 32b 
for blocking passage of the bulged portion 15. The lever 31 is rockable 
about a shaft 33 back and forth in the direction of movement of the wire 
13b, and, under the influence of the action of a toggle spring 34, capable 
of assuming a restraining position where the operating wire 13b is located 
in the narrow slit portion 32b and a relieving position where the 
operating wire 13b is located in the broad slit portion 32a. Stoppers 35a 
and 35b are provided for holding the lever 31 in the restraining and 
relieving positions, respectively. The outer end of the lever 31 is 
projected to the outside through the housing of the operating section 11 
to be gripped in the operator's hand, so that the operator can operate the 
lever 31 with a finger. 
With this arrangement, if the lever 31 is held in the restraining position 
in an angling operation, the forward displacement of the second operating 
wire 13b is restrained by the engagement of the sleeve 30 with the narrow 
slit portion 32b of the lever 31, permitting to bend only a fore end 
portion of the angle portion 10b. When the lever 31 is tilted into the 
relieving position, the sleeve 30 is allowed to pass the broad slit 
portion 32a of the lever 31, so that the whole angle portion 10b can be 
bent arcuately. 
In the foregoing embodiments, the fore end of one operating wire 13a is 
stopped on the angle ring 12a in the foremost position in the angle 
portion 10b while the fore end of the other operating wire 13b is stopped 
to the angle ring 12d in the fourth position. However, it is also possible 
to stop one operating wire on the rigid tip end portion 10c, while 
stopping the other or second operating wire 13b on an angle ring in a 
suitable posterior position depending upon the intended bending angle of 
the rigid tip end portion 10c. In this connection, the bending angle can 
be increased by stopping the fore end of the second operating wire 13b to 
an angle ring in a position closer to the base end of the angle portion 
10b, although such arrangements often result in a difficulty of bending 
the entire body of the angle portion 10b smoothly into an arcuate form. In 
such a case, it is advisable to add another operating wire along the 
second operating wire 13b, stopping the fore end of the additional 
operating wire on the foremost angle ring 12a or on the rigid tip end 
portion 10c and the rear end on the angle drum. In addition to the 
particular examples shown and described herein, the restraint force may be 
applied by the use of a magnetic clamp means, frictional clamp means, 
resisting means employing a spring or the like.