Abstract:
An endoscope having a sheath having a plurality of lumens, an imaging bundle received in a first lumen in the sheath, and a lighting bundle received in one or more second lumens in the sheath. A distal tip connects to a distal end of the sheath and includes an objective lens disposed in the distal tip, wherein the objective lens is spaced apart from the distal end of the imaging bundle.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]     This application claims priority to U.S. Provisional Patent Application No. 60/476,474, filed Jun. 5, 2003, which is incorporated herein by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     Endoscopes are expensive pieces of surgical equipment which are difficult to clean and sterilize between different patients. Moreover, endoscopes contain fiber optic bundles of lighting and imaging fibers which are rather fragile. Therefore, a problem that is common to endoscopes is that they break easily, especially when being cleaned and sterilized. For example, a typical lifetime is only about ten uses when re-using uretroscopic endoscopes.  
         [0003]     What is desired, therefore, is an endoscope which can be manufactured much more inexpensively than is possible with current designs. Specifically, the need exists for an endoscope which can be made so inexpensively (e.g.: by reducing both its component costs and manufacturing steps) that it would be disposable.  
       SUMMARY OF THE INVENTION  
       [0004]     In one aspect of this invention, an endoscope, including a sheath having a plurality of lumens; an imaging bundle received in a first lumen in the sheath; a lighting bundle received in one or more second lumens in the sheath; a distal tip connected to a distal end of the sheath; and an objective lens disposed in the distal tip, wherein the objective lens is spaced apart from the distal end of the imaging bundle.  
         [0005]     In another aspect of this invention, a method of forming an endoscope, including the steps of providing a sheath having a plurality of lumens; inserting an imaging bundle into a first lumen; inserting a lighting bundle into one or more second lumens; simultaneously cutting the distal ends of the sheath and the imaging and lighting bundles; and attaching a distal tip over the distal end of the sheath, the distal tip comprising an objective lens, wherein the distal tip is spaced apart from the distal ends of the imaging and lighting bundles. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]     The invention will now be described in greater detail with reference to the preferred embodiments illustrated in the accompanying drawings, in which like elements bear like reference numerals, and wherein:  
         [0007]      FIG. 1  is a sectional view of the distal end of a sheath, with lighting and imaging fiber bundles passing therethrough, prior to attaching a novel clear distal tip, in accordance with the present invention. (Corresponding to line  1 - 1  in  FIG. 2 ).  
         [0008]      FIG. 2  is a sectional view taken along line  2 - 2  in  FIG. 1 .  
         [0009]      FIG. 3  shows the attachment of the clear distal tip to the sheath/fiber bundle structure of  FIG. 1 .  
         [0010]      FIG. 4  is a sectional view of the distal end of a common pre-existing endoscope design.  
         [0011]      FIG. 5  is a sectional view of an alternative embodiment of the distal tip.  
         [0012]      FIG. 6  is a sectional view taken along line  6 - 6  in  FIG. 2  showing an optional embodiment of the present invention with pull wires passing through the distal tip. 
     
    
     DESCRIPTION OF THE INVENTION  
       [0013]      FIGS. 1 and 2  show the sheath  20 /fiber bundles  30 ,  40  of the present endoscope  10 . In this example, the sheath  20  has three lumen  22 ,  32 ,  42  passing therealong. It is to be understood that sheaths  20  having additional (or fewer) lumen are also encompassed by the present invention. As can be seen in  FIG. 2 , a fiber optic lighting bundle  30  is received in a first lumen  32  and a fiber optic imaging bundle  40  is received in a second lumen  42 . The third lumen  22  is left open and functions as a large central working channel  50 .  
         [0014]     In a preferred method of making the present invention, the system of  FIGS. 1 and 2  is first assembled, and thereafter the distal tip  60  shown in  FIG. 3  is attached. For reasons that will be explained, the distal tip  60  shown in  FIG. 3  will preferably be made of a light transmitting or more preferably “clear” material. Exemplary light transmitting materials include glass and plastic. It is to be understood, however, that the present invention also encompasses embodiments in which the distal tip  60  is not clear, with light instead passing through a lumen in the distal tip  60 .  
         [0015]     An advantage of manufacturing the present system by first assembling the components of  FIGS. 1 and 2 , and then attaching the clear distal tip  60  of  FIG. 3  is as follows.  
         [0016]     As can be seen in  FIG. 1 , very long sections of sheath  20  can be made with imaging  40  and lighting bundles  30  pre-fit therein. Then, these very long sections of sheath  20 /fiber bundles  30 ,  40  can be cut into individual endoscopes  10  of desired lengths. At the time of this cutting, both the sheath  20  and the fiber (lighting and imaging) bundles  30 ,  40  disposed therein will be cut cleanly together at its distal end  12 . By cutting the sheath  20  together with its imaging and lighting bundles  40 ,  30  at the same time, (as a single unit), the distal ends  12  of the imaging and lighting bundles  40 ,  30  will be polished when they are cut. If the bundles  30 ,  40  are plastic, the cutting and polishing may be done with a hot wire. Alternatively, if the bundles  30 ,  40  are glass, they can be simultaneously cut, ground and polished.  
         [0017]     A result of performing a single cut through the sheath  20  and its imaging and lighting bundles  40 ,  30  results in the distal ends  12  of these three elements all being co-planar to one another. In contrast, pre-existing endoscopes  100  did not have the distal ends  102  of the imaging and lighting bundles  130 ,  120  disposed co-planar to one another. This was due to the fact that an objective lens  140  needs to be attached to the distal end of the imaging bundle  130 . (An example of such a pre-existing system is shown in  FIG. 4 .)  
         [0018]     Thus, systems of manufacturing these pre-existing endoscopes  100  did not cut/polish the ends of the imaging and lighting bundles  120 ,  130  together as is conveniently accomplished by the present invention. Rather, these common pre-existing endoscopes  100  were assembled by first cutting the sheath  110  to a desired length, and then separately cutting and polishing the distal ends  132 ,  122  of the imaging and lighting bundles  130 ,  120 , slipping a ferrule (metal ring) around the distal end  132  of the imaging bundle  130  and then inserting each of the imaging and lighting bundles  130 ,  120  into separate lumens in the sheath  110 . As such, the ferrule is used to connect the lens  140  and the distal end  132  of the imaging fiber  130  together. This approach was time consuming. First, since the sheath  110  and each of the lighting and imaging bundles  120 ,  130  were separately cut and finished. Second, since the lighting and imaging bundles  120 ,  130  were separately advanced through lumens in the sheath  110 . Third, since the distal ends  112 ,  122 ,  132  of the sheath  110  and lighting and imaging bundles  120 ,  130  had to be aligned.  
         [0019]     The present invention is thus able to simplify manufacturing steps considerably by positioning the distal ends  44 ,  34  of the imaging and lighting bundles  40 ,  30  co-planar to one another. In accordance with a preferred aspect of the invention, the objective lens  70  is positioned in alignment with, and distal to, the imaging bundle  40  without the distal end  34  of the lighting bundle  30  having to be co-planar with the distal end  74  of the objective lens  70  (as in  FIG. 4 ), by instead using a novel “clear tip” distal end  60 , as follows.  
         [0020]     Referring to  FIG. 3 , a “clear” distal tip  60  is received over the distal end  12 , of components  FIGS. 1 and 2 . This distal tip  60  may preferably be made from glass, or more preferably, from plastic.  
         [0021]     A first advantage of the distal tip  60  being made of a clear material is that light from the end of the lighting bundle  30  will diffuse therethrough such that the target tissue will be illuminated even though the distal end  34  of the lighting bundle  30  is positioned proximally (i.e. upstream) of the distal end  74  of the objective lens  70 . Moreover, depending on the specific material used to make the clear distal tip  60 , the light exiting the lighting bundle  30  may diffuse widely, thereby illuminating a larger tissue surface area than could be accomplished with a pre-existing system as shown in  FIG. 4  where the distal end  122  of the lighting bundle  120  and the objective lens  140  are co-planar. Moreover, materials having a higher index of refraction could potentially exhibit more diffuse lighting therethrough, thus illumination a greater tissue surface area.  
         [0022]     A second advantage of the present distal tip  60  is that it can be pre-fitted with the objective lens  70  therein. (This advantage is true even if the distal tip  60  is not made of a clear material). As such, there is no need to attach, or otherwise position, the objective lens  70  to the distal end  44  of the imaging bundle  40  (as was done, for example in the prior art system seen in  FIG. 4 ). A disadvantage of the approach seen in the pre-existing system of  FIG. 4  is that, by gluing the objective lens  140  to the imaging bundle  130 , partial or complete lens separation from the imaging bundle  130  can occur. Such lens  140  separations tend to disrupt the picture, most notably by producing rainbow effects.  
         [0023]     Therefore, the lens  70  would preferably be mounted into the distal tip  60  with an appropriate anti-reflective coating to assure optimal image transmission. Alternatively, the lens  70  and tip carrier could be could be made as separate components and then assembled into the distal tip  60 .  
         [0024]     A third advantage of the system shown in  FIG. 3  is that an air space “gap”  72  is preferably provided between the distal end  44  of the imaging bundle  40  and the proximal end  76  of the objective lens  70 . This feature is not seen in any pre-existing system. It offers many advantages. For example, the bending stresses in the imaging bundle  40  are not transmitted to the objective lens  70  at all. Moreover, frequencies of light which may cause the imaging (and lighting) bundles  40 ,  30  to overheat would not necessarily cause the objective lens  70  to overheat, since heat from the bundle(s)  30 ,  40  would not be conducted directly into the lens  70 , due to the presence of the “air gap”  72 . Furthermore, the advantageous use of an “air gap”  72  between the distal end  44  of the imaging bundle  40  and the proximal end  76  of the lens  70  would still be advantageous even in those embodiments in which the distal end  32  is not clear (i.e.: in which light from the lighting bundle  30  instead passes through a lumen in the distal tip  60 ).  
         [0025]     A fourth advantage of the present clear tip design is that it can be easily attached to the distal end  12  of the endoscope  10 . For example, a thin layer of adhesive  80  can be provided between the inner surface  62  of the clear tip  60  and the outer surface  26  of the sheath ( FIG. 3 ). Any medically acceptable adhesive that will not damage the optical surface of the instrument is potentially of use in the invention. In one embodiment, this thin adhesive layer  80  can be made from a UV curable adhesive, for example a UV-curable epoxy adhesive. Thus, when the distal end  12  of the endoscope  10  is exposed to UV light, the epoxy will “cure”. A distinct advantage of the present clear tip design is that such UV light will simply pass through the tip  60  and reach the epoxy disposed thereunder. Thus, the present epoxy can be cured by UV light although it is positioned between two separate components of the system. This advantageously reduces manufacturing steps and their associated costs. Another useful feature of the design as shown is that the adhesive  80  is not in the light path, minimizing potential interference of the adhesive  80  with image quality or brightness. It can be appreciated that any suitable adhesive  80 , which can reliably adhere the tip  60  to the outer surface  26  of the sheath  20  can be used.  
         [0026]     Alternatives to adhesives  80  can also be used. In particular, sonic or heat welding can join parts, especially plastic parts. The use of detents or other mechanical interlocks is possible, but might raise costs. Interference fits are possible, but it will generally be better to supplement such contacts with adhesive, for safety.  
         [0027]     A fifth advantage of the clear tip  60  is that it can be made of a material which only passes selective wavelengths of light therethrough. This can be advantageous when using therapeutic compounds which are activated by specific frequencies of light.  
         [0028]     In addition, the clear tip is preferably constructed optionally with lenses to focus and distribute the illuminating light in the area, which is imaged by the imaging lens.  
         [0029]     It is expected that the time and energy saved by: (1) simultaneously cutting the sheath  20  length while polishing the distal ends of the imaging and lighting bundles  40 ,  30 , and then simply (2) attaching the clear tip  60  to the distal end  12  of structure, will result in an endoscope  10  which can be manufactured inexpensively enough that it is disposable.  
         [0030]     An alternative shape of the tip  60  is shown in  FIG. 5 . As shown in  FIG. 5 , the tip  60  has curved surfaces  68  in it, so it can act as a lens, especially for the imaging fiber bundle  40 . Such surfaces  68  can be cast integrally with the tip  60  during its manufacture, for example by injection molding. As shown, the surfaces  68  are simple curves, but aspheric surfaces may be preferred so as to focus as much light as possible on the entrance pupil of the fiber bundle  30 ,  40 . If required, a corresponding aspheric could be positioned at the exit of the fiber bundle  30 ,  40  to reshape the image.  
         [0031]     A second alternative feature also shown in  FIG. 5  is a projection rim  90  that fits inside the central working lumen  50 . Either by closeness of fit, or by virtue of adhesive for a reliable seal, the rim  90  seals the empty optical space so that fluid cannot get into the optical path during the procedure.  
         [0032]     As can be seen in  FIG. 3 , the clear tip  60  also has a central working channel  52  passing therethrough, which can be placed in alignment with the working channel  50  of the sheath  20 , permitting tool or irrigation access therethrough.  
         [0033]     As illustrated in  FIG. 3 , the distal tip  60  may be cylindrical. More preferably, the distal end  64  of the distal tip  60  can be beveled or curved to minimize the potential for tissue trauma as the endoscope  10  is advanced into the patient.  
         [0034]     Lastly,  FIG. 6  shows an embodiment of the present invention corresponding to a view taken along line  6 - 6  in  FIG. 2 , showing optional pull wires  94  passing through the distal tip  60 . The drawing illustrates a useful design option that can simplify assembly. Here, a funnel-shaped  98  feature in the distal tip  60  retains the pull wire  94 . The wires  94  can be threaded into the endoscope  10  after the distal tip  60  is bonded in place, simplifying assembly. Moreover, the application of force to pull wires  94  will tend to pull the tip  60  against the distal sheath  20 . In another embodiment, the funnels  98  in  FIG. 6  can be deeper, so that the bead  96  on the pull wire  94  is essentially retained by the mechanically strong sheath  20 . Alternatively, the pull wires  94  can be inserted in such a slot in the sheath  20 , and then the tip  60 , optionally lacking openings for pull wires  94  would be bonded in place.  
         [0035]     The endoscope  10  has been illustrated with two pull wire lumens  16 , a working lumen  52 , and one lumen  32 ,  42  each for lighting and imaging. This is a minimal configuration, and embodiments having more lumens are within the scope of the invention. For example, there could be three or four pull wire lumens  16 , and two or three lighting lumens, for example as shown in U.S. Pat. No. 6,458,076, by the same inventor.  
         [0036]     While this invention has been described with reference to the preferred embodiments described above, it will be appreciated that the configuration of this invention can be varied and that the scope of this invention is defined by the following claims.