Surgery – Endoscope – Having imaging and illumination means
Reexamination Certificate
2001-07-13
2002-12-24
Leubecker, John P. (Department: 3739)
Surgery
Endoscope
Having imaging and illumination means
C600S168000, C074S089390
Reexamination Certificate
active
06497652
ABSTRACT:
BACKGROUND OF THE INVENTION
This application claims the priority of Japanese Patent Application No. 2000-232811 filed on Aug. 1, 2000 which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a linear transmission member driving unit for an endoscope, and more particularly to a structure of a driving unit for rotating, by a motor, a linear transmission member for changing an observation distance (including changing depth of field).
2. Description of the Prior Art
FIGS. 4 and 5
show a structure (for example, Japanese Patent Laid-Open No. 2000-111806) of an endoscope, to which a mechanism for making an observation distance (or depth of field) variable is applied, and first with reference to
FIG. 5
, the description will be made of the endoscope as a whole. The endoscope is constituted by an operating unit
1
A, an insertion portion
1
B having flexibility and a tip end portion
1
C, and the operating unit
1
A is provided with a air-supply/water-supply operating button
2
A, a suction operating button
2
B, a freeze switch
3
, an observation distance variable switch
4
and the like. This observation distance variable switch
4
is capable of changing a focal length to a far direction or a near direction.
In this operating unit
1
A, a motor
7
is mounted on a chassis
6
by means of a holding member
8
, and to this motor
7
, a linear transmission member
10
consisting of a multiple coiled spring is mounted through a shaft connector
11
. This linear transmission member
10
is inserted in a protective tube
12
for preventing any interference with other members, and this protective tube
12
is attached to the chassis
6
by means of the holding member
13
. These linear transmission member
10
and protective tube
12
are arranged from the operating unit
1
A to the tip end portion IC through the insertion portion
1
B.
At this tip end portion
1
C, there are provided an objective optical system
14
and a CCD
15
, which is a solid state imaging device, and a movable lens installed in this objective optical system
14
for making the observation distance variable is driven by the linear transmission member
10
. More specifically, as shown in
FIG. 4
, at the tip end portion
1
C, there are arranged a front-side lens
17
, a movable lens
18
, and a prism
19
, and below the prism
19
, a CCD
20
is optically connected. The holding member
22
of the movable lens
18
has a female threaded portion in its top portion, and there is arranged a rotary driving member
23
, whose male threaded portion threadedly engages this female threaded portion, and to this rotary driving member
23
, the linear transmission member
10
is coupled.
Further, the rotary driving member
23
is provided with a first stopper
25
A having a male threaded portion at its end and a second stopper
25
B in such a manner that the inside of a wall portion, in which the inside diameter at a rear end of the holding member
22
becomes smaller, abuts on the first stopper
25
A, and the outside abuts on the second stopper
25
B.
According to such structure, rotation of the motor
7
is transmitted to the rotary driving member
23
at the tip end portion
1
C through the linear transmission member
10
, and the rotational motion of this rotary driving member
23
is converted into a straight-line motion by means of a combination of threaded engagement with the holding member
22
. Thereby, the movable lens
18
moves back and forth within a range D
1
(
FIG. 4
) to be set by the first stopper
25
A and the second stopper
25
B, and it becomes possible to change the observation distance to be set by the objective optical system.
BRIEF SUMMARY OF THE INVENTION
OBJECT OF THE INVENTION
In the above-described linear transmission member driving unit, however, the linear transmission member
10
consists of a multiple coiled spring, by means of which the operating unit
1
A and the tip end portion
1
C are coupled over a comparatively long distance therebetween, and therefore, driving control is not linearly performed, but particularly the response at the driving end (terminal end) is not satisfactory. More specifically, in the driving control of the motor
7
, the holding member
22
of the movable lens
18
abuts on the first stopper
25
A or the second stopper
25
B to reach the driving end, and when a load to be given to the rotating shaft of the motor
7
through the linear transmission member
10
exceeds a predetermined value, the motor
7
is controlled to be stopped.
However, since the rotary driving force to be transmitted from the motor
7
is absorbed by the kink of the linear transmission member
10
, no stop control is performed in the control circuit before a fixed amount of load is applied to the motor
7
since the movable lens
18
stops at the driving end. Also, even when the direction of rotation is reversed at the driving end, since the movable lens
18
starts to move after the kink of the linear transmission member
10
is completely returned, a time lag occurs between when the observation distance variable switch
4
is operated, and when actually driven, and as a result, the operability is worsened.
Also, in order to move the movable lens
18
, a force to be given to the tip end portion driving member is increased by the kink of the linear transmission member
10
, and since a miniaturized driving member is used for the tip end portion of the endoscope which has particularly a fine diameter, the durability of the tip end portion driving member is deteriorated. Similarly, there was a problem that the durability of the linear transmission member
10
itself is also deteriorated due to the kink.
As means for avoiding such a problem, it can be conceived to reinforce the linear transmission member
10
, and to increase its diameter so as not to cause any kink phenomenon even for the maximum driving force for improving the transmission ability. Even in this case, however, it is possible to reduce the time lag between during operating and during driving to some extent, but sufficient response cannot be obtained. And yet, this observation distance variable operation is structured so as to be able to change the operating speed stepwise, and since the linear transmission member
10
becomes heavier by increasing the diameter, it becomes difficult to execute high-speed operation.
Also, when the diameter of the linear transmission member
10
is increased, the hardness also becomes higher, and therefore, the transmission characteristic of the linear transmission member
10
is deteriorated because of a change in posture of the insertion portion
1
B which can be freely bent, and there is also an inconvenience that there occurs a difference in time required for the observation distance variable operation.
The present invention has been achieved in view of the above-described problems, and an object of the present invention is to provide a linear transmission member driving unit for an endoscope capable of obtaining high operability in the function for making the observation distance variable and the like by improving the response of driving control, and improving durability of the tip end portion driving member and the linear transmission member.
SUMMARY OF THE INVENTION
In order to achieve the object, according to the present invention, there is provided a linear transmission member driving unit comprising: a linear transmission member which rotates to drive an object; a motor, to which this linear transmission member is shaft-connected; a guide member for regulating a range of movement of the object driven by the linear transmission member; and a rotation stopper mechanism arranged between the linear transmission member and the motor, for stopping the rotation of the linear transmission member correspondingly to a range of movement of the object regulated by the guide member.
The another invention is characterized in that it is arranged such that rotation of the linear transmission member is transmitted to a lens driving unit, to make a movable lens f
Fuji Photo Optical Co., Ltd.
Leubecker John P.
Snider Ronald R.
Snider & Associates
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