Surgery – Endoscope – With guide means for body insertion
Reexamination Certificate
1999-05-05
2002-03-19
Mulcahy, John (Department: 3739)
Surgery
Endoscope
With guide means for body insertion
C600S102000, C600S104000, C604S271000, C604S172000
Reexamination Certificate
active
06358199
ABSTRACT:
The present invention relates to a flexible eversion tube system for an endoscopy instrument and, in particular, a drive means for the drive of a respective flexible eversion tube.
BACKGROUND OF THE INVENTION
From the prior art according to DE 42 42 291 A1, for instance, an endoscope including a flexible eversion tube design of this species is known.
This endoscope substantially comprises an endoscope head or a distal end, to which an endoscope shaft of a flexible resilient tubular body is connected, and an operating means at the rear end of the endoscope shaft. The operating means has a number of actuating wheels rotatably supported at the endoscope shaft which are operatively connected with the distal end via operating wires or Bowden cables laid inside the endoscope shaft. Furthermore a first drive or feed means exerting a driving force on the endoscope shaft via drive wheels is provided in a rear end portion of the endoscope.
Around the endoscope shaft at least in the leading portion thereof a flexible eversion tube which is driven by a second drive or feed means is arranged. The flexible eversion tube consists of an inner tube section being slidably adjacent to the surface shell of the endoscope shaft and being eversed in the area of the distal end of the endoscope to form a leading outer tube section The leading outer tube section is further returned to the second drive means and is fixed to the casing thereof. In the rear portion of the endoscope the inner tube section is eversed to form a trailing outer tube section which is likewise returned to the second drive means and is fixed to the casing thereof at the axial end face opposed to the leading outer tube section.
The second drive means acts on the inner flexible eversion tube section to move the same in the axial direction of the endoscope shaft. To this effect, the second drive means includes a kind of collar which contracts in radial direction and, in so doing, can be frictionally engaged so as to be pressed against the inner tube section and can further be moved in axial direction of the endoscope in a reciprocating manner. In another variant of this second drive means a number of friction wheels arranged at an angular distance from each other is provided, which friction wheels sit close on the inner tube section and thus exert a substantially continuous feed motion on the inner tube section. The radially acting pressing forces of the collar and/or the friction wheels of the second drive means are selected to be such that at least part of the pressing forces applied is transmitted to the surface shell of the endoscope shaft by a deformation of the material of the inner tube section so that the endoscope shaft is advanced along with the inner tube section despite the relative sliding capacity.
Since with this only type of drive by the second drive means, i.e. without the first drive means, the rate of feed of the flexible eversion tube at its leading eversing portion would only be half of that of the endoscope shaft due to the eversing movement thereof, that is to say the endoscope shaft would move out of the flexible eversion tube in a telescopic manner with an increasing penetrating depth into the hollow, the aforementioned first drive means exerts a brake force on the endoscope shaft counteracting the feed force of the second drive means.
The second drive means is synchronized with the first drive means in such manner that by interaction of the two drive means the rate of movement of the inner tube section in axial direction is approximately twice as high as the rate of movement of the endoscope shaft, the latter sliding relative to the inner endoscope shaft (i.e. the distal end of the endoscope shaft moves at the same rate as the leading eversing portion of the flexible eversion tube).
In order to facilitate the relative movement between the endoscope shaft and the flexible eversion tube, the prior art according to DE 42 42 291 A1 further provides a lubricating device by the intermediary of which a lubricant can be forced into a gap between the inner tube section and the endoscope shaft as well as into a hollow between the inner and outer tube sections. To this effect, the lubricating device, inter alia, has a tapered sleeve which is slipped on the endoscope shaft and sealingly interacts with the trailing eversing portion of the flexible eversion tube which is put on the tapered sleeve. The lubricant forced into a gap between the tapered sleeve and the endoscope shaft by a pump spreads between the inner tube section and the endoscope shaft over the total length of the flexible eversion tube, excessive quantities of the lubricant in the leading eversing portion of the flexible eversion tube penetrating into the hollow to be examined.
In accordance with an in-house prior art, the inventor is moreover involved in developing an endoscopy instrument using a double flexible eversion tube system according to the aforementioned species, as it will be briefly described hereinafter:
This endoscopy instrument comprises an endoscope shaft slidably guided in a tube eversed on both sides which in turn is movable by a drive means acting upon the inner tube section of the flexible eversion tube. The drive means comprises at least one continuous feed means, especially frictional wheels arranged at a uniform angular distance which can be pressed radially onto the inner tube section to move the latter in a substantially continuous manner in axial direction of the shaft. This has the important advantage that the continuous advance of the flexible eversion tube system can be exactly controlled and thus, for instance, the distal end of the endoscope can be guided accurately on the spot.
It is provided in this context that the pressing force of the feed means on the inner tube section is selected such that the shaft is in direct frictional contact with the inner tube section at least in the area of the feed means. The feed means is formed by one or more frictional wheels which are biased against the inner tube section at a predetermined or adjustable pressing force so that, on the one hand, a continuous feed and, on the other hand, a possibly slip-free feed of the endoscope shaft into a patient's hollow to be examined is ensured.
Moreover the drive means comprises means for synchronizing the shaft movement with the movement of the flexible eversion tube. This may be a rear or front end piece or clamping piece axially fixed to the shaft on which the trailing or leading eversing portion of the flexible eversion tube dependent on the feed direction sits close in a slidable manner so that the flexible eversion tube applies a brake force opposing the presently prevailing feed force of the feed means to the endoscope shaft via the rear or front end pieces.
Numerous tests carried out by the inventor have shown that in an endoscopy instrument of such design comprising the above-described flexible eversion tube system the feed forces applicable by the frictional wheels are limited, however. The reason herefor is that the feed forces of the frictional wheels can be applied only partially to the endoscope shaft via the inner tube section, because between the inner tube section and the surface shell of the endoscope shaft as well as between the frictional wheels and the inner flexible eversion tube section a lubricating film is formed permitting, on the one hand, a relative sliding movement between the endoscope shaft and the inner tube section and, on the other hand, causing a slip between the drive wheels and the inner tube section. This means that part of the theoretically possible feed force of the frictional wheels on the endoscope shaft gets lost. Moreover, it has turned out that the friction contacts between the individual drive wheels and the inner tube section may be different, whereby, in this case, the drive forces of the individual wheels are transmitted to the inner tube section in a nonuniform manner. The one-sided axial load of the radially inner tube section resulting herefrom entails a tilting and crinkling of the flexibl
Pauker Fritz
Pauker Robert
Viebach Thomas
Weiglhofer Gerhard
Graybeal Jackson Haley LLP
Mulcahy John
Ram Jocelyn
STM Medizintechnik Starnberg GmbH
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