Surgery – Endoscope – Having imaging and illumination means
Reexamination Certificate
2000-01-26
2002-06-04
Leubecker, John P. (Department: 3739)
Surgery
Endoscope
Having imaging and illumination means
C600S161000, C359S819000, C359S503000, C359S808000, C359S435000
Reexamination Certificate
active
06398723
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an endoscope having a tubular shaft in whose interior is arranged at least one component, in particular lenses, aperture stops, filters, of an optical system, at least one support element that at least partially surrounds the component being provided between the outer side of the component and the inner side of the tubular shaft.
An endoscope of this kind is known from U.S. Pat. No. 4,148,550.
Endoscopes are used generally in surgery to inspect body cavities and hollow organs. Endoscopes have an elongated tubular shaft in which components of an optical observation system are arranged. Further apparatuses, usually a light delivery apparatus, and optionally ducts for instruments, flushing fluid, or the like, are often provided in the interior of the endoscope shaft. Light delivery is usually accomplished via light-guiding optical fibers.
In this case the optical system is received in a separate inner tube in the endoscope shaft.
Endoscopes can be of rigid or flexible configuration, the endoscope shaft correspondingly being manufactured from metal or a flexible plastic material.
The optical systems provided in endoscopes are constructed from components arranged along the tubular shaft axis, such as lenses (in particular rod lenses of the so-called Hopkins optical system), aperture stops, filters, and the like, and their purpose is to reproduce an image of as large a field of view as possible with high resolution and high contrast. The most important prerequisite for this is precise arrangement of the components of the optical system in the tubular shaft of the endoscope. The relative positions of the components of the optical system are not variable but rather are precisely defined, since any shift in the components relative to one another results in decreased image sharpness and resolution.
The components therefore must be precisely immobilized in the tubular shaft of the endoscope so as to remain there immovably.
The components of an optical system are usually slid into the tubular shaft of the endoscope, spaced apart from one another with spacers, and immobilized using end-located terminating elements. This type of immobilization system is insufficient, however, since tolerances can result in radial movement back and forth. A thin air gap is present between the outer side of the components and the inner side of the tubular shaft, or the components rest by way of their outer sides against the inner side of the tubular shaft.
In addition, and most importantly, the lenses of the optical system, made of glass material, can break during handling of the endoscope, for example if the endoscope is dropped or set down too firmly onto a hard surface, since because of the very thin air gap between component and tubular shaft, even slight flexing of the tubular shaft can cause forces or torques to act on the components and result in the breakage of lenses.
This problem has been tackled, for example in the case of rod lenses, by way of a “dog-bone” shape for the lens, i.e. a shape in which the ends of the rod lens have enlargements, called rim cylinders. A conforming fit with the tubular shaft is then present only in the region of the rim cylinders, and the remaining periphery of the rod lens is separated from the tubular shaft by a gap.
During cleaning, shocks occur (due to ultrasound, dishwasher, etc.) that cause the lenses to strike against the inner tube as a result of their radial clearance. Impacts also occur between the lens and spacing element (due to wear, contamination, etc.).
One solution to the problem of joining the lenses of an optical system in an endoscope to one another is described in the aforesaid U.S. Pat. No. 4,148,550.
The endoscope described therein has an outer protective tube on whose inner side a layer with light-transmitting fibers is provided, and an inner tube in which a number of rod lenses, which form an optical system, are arranged axially one behind another.
As already mentioned, it is necessary for the operation of the optical system for the rod lenses to be arranged at a defined axial spacing from one another in the inner tube of the endoscope. Spacers in the form of spacer tubes, usually made of metal, are used for this purpose in the existing art.
In U.S. Pat. No. 4,148,550, the join between the rod lenses is created using sleeve-shaped elements which enclose the lens ends of at least two adjacent lenses.
These elements are made of a flexible sleeve-shaped material and have longitudinally extending slots that are provided for the introduction of a tool and the passage of cleaning gases or liquids for the lenses. In addition to holding together the rod lenses that are arranged one behind another, the elements also serve to allow the flexible endoscope to bend while preventing breakage of the rod lenses. These elements themselves can provide bracing with respect to the inner wall of the tubular shaft, but additional annular support elements can also be provided.
Attachment or immobilization of the rod lenses, joined by way of the support elements, in the inner tube of the endoscope is accomplished by press-fitting, specifically by the fact that, for example, a slightly oval or triangular cross section is imparted to the inner, initially cylindrical tube enclosing the rod lens system, so that the rod lenses, with their round cross section, are firmly press-fitted. It is further proposed to use suitable adhesives.
The elements provided in this U.S. Pat. No. document provide for the rod lenses to be joined to one another, and provide for bracing against the parts of the endoscope that surround them. The axially nondisplaceable join must be effected separately, since otherwise the lens arrangement as a whole can move axially back and forth in the interior of the endoscope, which is undesirable due to the adverse effect on optical quality and the risk of breakage of lens elements.
DE 19 12 720 C2 discloses an endoscope whose tubular shaft is made of a transparent and optically clear plastic material into which the optical elements of the objective and the lens system are placed. This hollow cylinder serves as a light guide in order to guide illumination light from the proximal to the distal end of the endoscope.
In order to shield the lenses present in the hollow cylinder from the entry of light from the light guiding system, a light-absorbing and/or reflective element is provided between the hollow cylinder and the objective or the lens system. This element can be configured as a plastic heat-shrink sleeve. The lenses of the lens system and the objective are first placed into this plastic heat-shrink sleeve and positioned in the correct position; then the heat-shrink sleeve is shrunk by the application of heat so that it holds the lenses. This assemblage is then slid into the tubular shaft. The purpose of the plastic heat-shrink sleeve is thus to hold the lenses in a specific orientation with respect to one another, and furthermore to serve as a light-absorbing or light-reflecting element.
DE 33 31 631 C2 has disclosed a lens retaining system for radial adjustment of rod lenses in an optical tube in the region of the lens ends, in which annular retaining means are provided which hold the lenses at a radial distance from the inner surface of the tube.
Against this background, it is the object of the present invention to create an endoscope of the kind cited initially in which the components of the optical system are immobilized as simply as possible but nevertheless securely in the interior of the tubular shaft, and also can be protected against the action of external forces or torques.
SUMMARY OF THE INVENTION
This object is achieved, in an endoscope, in that the support element is manufactured from a shrinkable material, and that the component is immobilized on the inner side of the tubular shaft by way of the support element shrunken in the tubular shaft.
A “shrinkable material” for purposes of the present invention is understood to mean on the one hand a cold-stretched thermo-plastic material th
Kehr Ulrich
Rudischhauser Jürgen
Karl Storz GmbH & Co. KG
Leubecker John P.
Ram Jocelyn
St. Onge Steward Johnston & Reens LLC
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