Surgery – Endoscope – Having imaging and illumination means
Reexamination Certificate
1999-12-14
2002-06-25
Mulcahy, John (Department: 3739)
Surgery
Endoscope
Having imaging and illumination means
C600S130000
Reexamination Certificate
active
06409658
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Art
This invention relates to an endoscope for medical use, incorporating an objective lens drive mechanism in association with an optical objective lens system on its insertion instrument, and more particularly to an endoscope with an objective lens drive mechanism permitting to shift the position of at least one lens element of an optical objective lens system in the direction of its optical axis by remote control to vary at least observation depth, image magnification scale or view field angle.
2. Prior Art
In general, endoscopes which are used for medical purposes are largely constituted by a manipulating head assembly to be gripped by an operator to control the operation of the endoscope, an insertion instrument extended out on the front side of the manipulating head assembly for insertion into a body cavity, and a universal cable led out from the manipulating head assembly for connection to a light source. In terms of construction and function, the insertion instrument is composed of a rigid tip end section, an angle section and a flexible rod section, from its fore distal end to proximal end. The flexible rod section, which occupies a major portion of the entire length of the insertion instrument, is arranged to be flexible in arbitrary directions along a path of insertion which may contain bends. The rigid tip end section is provided with at least an illumination window and an observation window, along with an outlet opening of a biopsy instrument channel which is usually provided in the insertion instrument for the purpose of insertion of forceps or other instruments. The angle section is flexible by remote control from the side of the manipulating head assembly. Accordingly, the rigid tip end section can be turned into an arbitrary direction by bending the angle section by remote control.
A light emitting end of a light guide, which consists of a bundle of fiber optics, is disposed in the illumination window on the rigid tip end section of the insertion instrument. The light guide is passed through the insertion instrument and assembled into the universal cable which is led out from the manipulating head assembly as mentioned above. Further, an objective lens system is mounted on an image pickup assembly block within the rigid tip end section of the insertion instrument, along with a solid-state image sensor device which is located at the focus of the objective lens system. Normally, the image pickup assembly block is located substantially at a central position in a cross-sectional area of the rigid tip end section. On the other hand, it is usually the case that an illumination window is provided at one or a plural number of positions in the vicinity of an observation window at the distal end of the image pickup assembly block. Accordingly, the center of observation view field is located substantially at a central position of the insertion instrument, and the illumination window or windows are arranged to irradiate the entire view field including center portions thereof.
The optical objective lens system of the endoscopic image pickup is normally constituted by an objective lens group which is composed of a plural number of lens elements. Preferably, the objective lens group should be able to vary at least the depth of focus, image magnification rate or view field angle depending upon the location of an observation site or the purpose of examination. In this regard, it has thus far been known in the art to arrange one or a plural number of lens elements of an objective lens group to be movable in the direction of optical axis of the objective lens system. For this purpose, an objective lens group is usually mounted on a lens frame which is constituted by a fixed lens frame and a movable lens frame. The movable lens frame is slidably fitted in the fixed lens frame which functions as a guide when the movable lens frame is moved in the direction of optical axis.
Accordingly, the optical objective lens system necessarily includes a drive means for moving the movable lens frame in the direction of optical axis. As for drive means of this sort, for example, there have been proposed a diversity of drives using piezoelectric elements, shape memory alloys, artificial muscle and the like. However, normally a proximal end of a control cable which is connected to a movable lens frame is extended into the manipulating head assembly of the endoscope thereby permitting to shift the position of a movable lens or lenses in the direction of the optical axis by remote control. The movable lens is moved between a fore position closer to the subject side and a rear position closer to the imaging side. Location of the movable lens in the rear position gives a smaller image magnification rate and a greater focal depth. On the other hand, location of the movable lens in the fore position gives a greater image magnification rate and a smaller focal depth. Accordingly, in this case, the operator can shift the position of the movable lens by driving same through the control cable or other suitable transmission member, depending upon the location of an intracavitary portion under examination or the nature of examination. This shift of the movable lens position is feasible even when the insertion instrument of the endoscope is inserted in a body cavity of a patient.
In order to pick up clear images through an optical objective lens system, a movable lens has to be located precisely in either one of the above-mentioned fore and rear positions. This is so especially when a movable lens is located in a fore position on the side of a subject because the focal depth is shallow in the fore position and therefore a slight deviation from a predetermined position will invite considerable deteriorations in quality of picture images. It follows that a movable lens should be positioned correctly at least when shifted to a fore position on the side of a subject. For remote-controlling a movable lens, a control cable is connected to a movable lens frame as mentioned above. Various forms of remote control cables of this sort have been known in the art, for example, from Japanese Laid-Open Patent Specification H4-13112 and Japanese Utility Model Publication S55-55041.
Disclosed in Japanese Laid-Open Patent Specification H4-13112 is a lens group consisting of a front group lens, a rear group lens and a magnification control lens which is movable in the direction of optical axis. The magnification control lens is arranged to slide along a slide member which is provided between front and rear lens frame which support the front and rear lens groups, respectively. The magnification control lens itself is fitted in a magnification lens frame, and an operating wire is connected to the magnification lens frame thereby to permit to move the latter back and forth by remote control from the manipulating head assembly. The operating wire is passed through and fixedly connected at its fore end to a wire threading member which is provided integrally with the rear group lens frame. The other end of the operating wire is connected to a solenoid which is energizable to shift the magnification control lens between a fore position on the side of the front group lens and a rear position on the side of the rear group lens. The control cable of this sort can be referred to as a push-pull type.
Disclosed in Japanese Utility Model Publication S55-55041 is an endoscope employing an image guide in such a way as to vary the distance between a light incident or input end of the light guide and an optical objective lens system. In this particular prior art, the image guide is moved by the use of a control cable. More particularly, in this case, a projection is provided on a mouth piece which is fitted around a fore end portion of an image guide, and a screw shaft threaded into the projection to connect thereto one end of a wire which is passed through a coil tube. In this case, the position of the light input end of the image guide is adjusted by rotating the wire about the longitudinal axis wit
Fuji Photo Optical Co., Ltd.
Mulcahy John
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