Linear transmission member driving unit for endoscope

Surgery – Endoscope – Having imaging and illumination means

Reexamination Certificate

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Details

C600S168000

Reexamination Certificate

active

06422995

ABSTRACT:

RELATED APPLICATIONS
This application claims the priority of Japanese Patent Application No. 11-344842 filed Dec. 3, 1999, and Japanese Patent Application No. 2000-77876 filed Mar. 21, 2000.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a linear transmission member driving unit for an endoscope, and more particularly to a driving unit for rotating a linear transmission member for changing an observation distance (including also changing depth of field) by a motor.
2. Description of the Prior Art
FIGS. 13A
to
13
C show a configuration of an endoscope (scope) to which a mechanism for making the observation distance (or depth of field) variable is applied, and
FIG. 13A
shows an endoscope operating unit
1
A, and on the left side of this operating unit
1
A, there are disposed an insertion unit
1
B shown in
FIG. 13B
, and a tip end portion (hard portion)
1
C shown in FIG.
13
C. In this respect, the insertion unit
1
B consists of the tip end portion
1
C, an angle portion
1
D and a soft portion
1
E. Behind the operating unit
1
A, there are disposed an air-supply/water-supply operating button
2
A, a suction operating button
2
B, a freeze switch
3
A, other switches
3
B and
3
C, and an observation distance-variable switch
4
or the like.
Also, within the operating unit
1
A, a motor
7
is mounted onto a chassis (base)
6
by a holding member
8
, and a linear transmission member
10
formed of a multiple coiled spring is mounted to this motor
7
through a shaft connector
11
. This linear transmission member
10
is placed within a flexible protective tube (soft tube)
12
in order to avoid any interference with other members, and this protective tube
12
is mounted to the chassis
6
with the holding member
13
. These linear transmission member
10
and protective tube
12
are disposed from the operating unit
1
A to the tip end portion
1
C through the insertion unit
1
B.
At the tip end portion
1
C, there are disposed, as shown in
FIG. 13C
, an object lens
15
, a movable lens
16
and a prism
17
, and a CCD
18
, which is a solid state imaging device, is optically connected below this prism
17
. A holding member
19
of the movable lens
16
has a female threaded portion on top thereof, and on this female threaded portion, there is disposed a rotary driving member
20
whose male screwed portion threadably engages with this female threaded portion, and the linear transmission member
10
is coupled to the rotary driving member
20
.
According to such a configuration, rotation of the motor
7
is transmitted to the rotary driving member
20
at the tip end portion
1
C through the linear transmission member
10
, and the rotary motion of this rotary driving member
20
is converted into a linear motion by means of threaded engagement with the holding member
19
. This enables the movable lens
16
to move back and forth, making it possible to make an observation distance to be set in the objective optical system variable.
BRIEF SUMMARY OF THE INVENTION
Object of the Invention
In an endoscope having the above described linear transmission member driving unit, when an angle portion
1
D of the insertion unit
1
B is curved as shown in
FIG. 13B
, the protective tube
12
advances and retreats by a length of, for example, L
1
, and the linear transmission member
10
advances and retreats by a length of, for example, L
2
in a rotating shaft direction. More specifically, on focusing attention on a certain point P on the protective tube
12
, it moves forward (toward a position P
1
) by a length L
1
when the angle portion
1
D is bent from a straight state. Since both end portions of the protective tube
12
are fixed to the neighborhood of its tip end portion
1
C and the holding member
13
, when the insertion unit
1
B is set to a just suitable length in a straight state, the protective tube
12
is pulled during the bending operation, and as a result, the tip end portion
1
C is deviated from a desired operating direction and tilts, so-called “crooked neck” occurs. Thus, conventionally, the length of the protective tube
12
has been made a little longer than the armored body, and when it is being bent, the scope insertion unit
1
B is disposed so as to push it into the protective tube
12
.
On the other hand, one end of the linear transmission member
10
is connected to the rotary driving member
20
, and is enveloped in the protective tube
12
, and therefore, when the angle
1
D is bent, the linear transmission member
10
moves backward (from position P to P
2
) by, for example, length L
2
. For this reason, there occurs an inconvenience that the linear transmission member
10
gives a load caused by pressure to the output shaft of the motor
7
, and a change in posture of the insertion unit
1
B changes the moving speed of the movable lens
16
, that is, the magnification changing time. Thus, the linear transmission member
10
is mounted with reference to the time during the bending operation of the insertion unit
1
B (during the maximum movement toward the motor side), and when the insertion unit
1
B is made straight, a moderate pulling force is caused by a multiple coiled spring (linear transmission member
10
) which expands and contracts so as to cause any load of the pressure not to be applied to the motor output shaft.
Since, however, the degree of expansion and contraction of the multiple coiled spring, which is the linear transmission member
10
, changes depending upon bending (change in posture) of the insertion unit
1
B including the angle portion
1
D even in the above described configuration, the load to the motor output shaft cannot be maintained constant, leading to a problem that the posture of the insertion unit
1
B causes variations in the magnification changing operation (operation of variable power).
Also, the angle portion
1
D configuring the endoscope is used to point a tip hard portion
1
C toward a desired direction, and is constructed so as to be curved by remote control from an angle operating device provided on the body operating unit
1
A. This angle portion
1
D is curved in order to mainly change the observation visual field of the endoscope. The insertion unit
1
B is inserted into a narrow body cavity in order to perform inspection and diagnosis, and the overall length of the angle portion
1
D is desirably made as short as possible in order to smoothly and reliably change the observation visual field even in the narrow body cavity or the like. Moreover, in order not to cause any dead angle in the observation visual field as far as possible, the angle of curvature must be made as large as possible. Accordingly, when the angle portion
1
D is curved to the maximum angle of curvature, the radius of curvature is exceedingly small, and yet it is configured to be able to be abruptly curved such as, for example, 180° or an angle of its vicinity. Also, since an insertion course within the body cavity has a complicatedly curved shape, the soft portion
1
E coupled to the angle portion
1
D has flexibility in a curved direction, and this soft portion is constructed so as to be able to be curved in any direction by following the curved insertion course.
The angle portion
1
D is constructed so as to be curved larger than the soft portion
1
E, and even in the protective tube
12
to be disposed within these, the inside of the angle portion
1
D is curved larger so that the soft protective tube
12
becomes deformed as if it were crushed. Therefore, within this angle portion
1
D, the frictional resistance of the linear transmission member
10
and the protective tube
12
becomes larger than the soft portion
1
E, resulting in irregularity of the rotary driving-force of the linear transmission member
10
, and there is a problem that the driving force lowers.
Further, in a state in which the angle portion
1
D has been curved to the maximum, the protective tube
12
may become deformed so as to become flat, but since the linear transmission member on the one hand has high rigidit

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