Abstract:
An endoscope comprising a control section and a shaft extending from the control section. The shaft has a frame with a one-piece tube along a majority of a length of the shaft. The tube comprises a superelastic alloy and slots into the tube along at least one-section of the tube. Superelastic properties of the superelastic alloy allow the tube to bend proximate the slots without substantial permanent deformation of the tube. The superelastic alloy provides the shaft with adequate stiffness and torque resistance to be inserted into a patient&#39;s body.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to medical instruments and, more particularly, to an endoscope. 
     2. Prior Art 
     U.K. Patent Application No. 2130885 discloses a flexible distal end portion for an endoscope. The end portion is made from plastic material with vertebrae connected by an elongate member or spine. U.S. Pat. No. 5,938,588 discloses an endoscope with wire sheaths made as solid tubes from a superelastic alloy material. 
     SUMMARY OF THE INVENTION 
     In accordance with one embodiment of the present invention, an endoscope is provided comprising a control section and a shaft extending from the control section. The shaft has a frame with a one-piece tube along a majority of a length of the shaft. The tube comprises a superelastic alloy and slots into the tube along at least one section of the tube. Superelastic properties of the superelastic alloy allow the tube to bend proximate the slots without substantial permanent deformation of the tube. The superelastic alloy provides the shaft with adequate column strength, flexibility and torque resistance to be inserted into a patient&#39;s body. 
     In accordance with another embodiment of the present invention, an endoscope is provided comprising a shaft, a fiber optic system and the working channel passing through the shaft, and a deflection control system passing through the shaft. The shaft includes a frame comprising a tube of superelastic material with slots into the tube. The slots extend into the, tube in at least two different directions. 
     In accordance with another embodiment of the present invention, an endoscope is provided comprising a control section; and a shaft extending from the control section. The shaft comprises a general tube shaped frame member. The shaft comprises a substantially uniform outer dimension along substantially an entire length of the shaft. The tube shaped frame member provides the shaft with at least two sections along the length of the shaft having two different flexibilities (stiffnesses). 
     In accordance with one method of the present invention, a method of manufacturing an endoscope shaft frame is provided comprising steps of providing a tube of superelastic alloy; and making slots into the tube to form at least one section of the tube with an increased flexibility. 
     In accordance with another method of the present invention, a method of manufacturing endoscopes is provided comprising steps of providing a first type of shaft frame comprising a first tube with a first pattern of slots into the first tube; providing a second type of shaft frame comprising a second tube with a second pattern of slots into the second tube, the second pattern, being different than the first pattern; and assembling a first one of the endoscopes with the first type of shaft frame and a second one of the endoscopes with the second type of shaft frame. The first and second endoscopes comprise different flexibility, torque resistance and column strength patterns along their lengths provided by the different patterns of slots in the first and second tubes. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing aspects and other features of the present invention are explained in the following description, taken in connection with the accompanying drawings, wherein: 
     FIG. 1 is a side elevational view of an endoscope incorporating features of the present invention; 
     FIG. 2 is a cross-sectional view of the shaft of the endoscope shown in FIG. 1; 
     FIG. 3 is a side elevational view of the tube used for the frame of the shaft shown in FIG. 2; 
     FIG. 4A is a cross-sectional view of the tube shown in FIG. 3 taken along line  4 A— 4 A; 
     FIG. 4B is a cross-sectional view of the tube shown in FIG. 3 taken along line  4 B— 4 B; 
     FIG. 4C is an enlarged view of a portion of the first section of the tube shown in FIG. 3; 
     FIG. 5 is a partial side elevational view of the tube shown in FIG. 3 being bent; 
     FIGS. 6A-6D are cross-sectional views of the third section of the tube shown in FIG. 3 showing the four different slot directions into the tube; 
     FIGS. 7A-7E are cross-sectional views of another alternate embodiment of a tube incorporating features of the present invention; and 
     FIG. 8 is a cross-sectional view of an alternate embodiment of a shaft. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, there is shown a side elevational view of an endoscope  10  incorporating features of the present invention. Although the present invention will be described with reference to the embodiments shown in the drawings, it should be understood that the present invention can be embodied in many alternate forms of embodiments. In addition, any suitable size, shape or type of elements or materials could be used. 
     The endoscope  10  generally comprises a handle or control  12  and a flexible or semi-flexibile shaft  14  connected to the handle  12 . The shaft  14  includes a passive deflection section  16  and an active deflection section  18  at the distal end of the shaft  14 . A control system  22  to control the active deflection section  18  extends from the handle  12  to the active deflection section  18 . Referring also to FIG. 2, the control system  22  generally comprises a pair of control wires  24   a ,  24   b , two wire sheaths  50   a ,  50   b , and an actuator  28 . The wires  24   a ,  24   b  are connected to the actuator  28  at one end and are connected to the active deflection section  18  at a second end. 
     In the preferred embodiment, the handle  12  has a user operated slide or lever  30 . The lever  30  is connected to the actuator  28 . The actuator  28  is adapted to pull and release the two wires  24   a ,  24   b  of the control system  22 . When the lever  30  is moved by the user, the actuator  28  is moved. The actuator  28  may be a drum or pulley rotatably connected to the handle  12  to pull one wire  24   a ,  24   b  while releasing the other. In an alternate embodiment, the actuator may be any suitable type of device, such as a rocker arm adapted to pull and release the wires of the control system  22 . In another alternate embodiment, where the control system may have two or more pairs of control wires, the handle will have additional actuators and corresponding controls to drive the additional pairs of control wires. In still other alternate embodiments, the handle may have knobs with rack and pinion mechanisms or other suitable user operated controls for the control system. 
     The shaft  14  is cantilevered from the handle  12 . In the preferred embodiment, the flexible shaft  14  has about an 8 Fr diameter. In alternate embodiments, the flexible shaft could have any suitable diameter. The flexible shaft  14  includes the control wires  24   a ,  24   b  of the control system  22 , a fiber optical image bundle  37 , a fiber optical illumination bundle  36 , and a working channel  38 . A port  60  for inserting instruments (not shown) into the channel  38  is located on the handle  12 . The handle  12  also has a light source post  62  for connecting a light source (not shown) to the illumination bundle  36 . In addition, the handle  12  has an eyepiece  63  for a user to view an image transmitted by the image bundle  37  from the front end  20 . In alternate embodiments, the flexible shaft may house different systems within. The shaft  14  generally comprises a frame  26 , a cover  32  and an objective head  34 . Referring also to FIG. 3, the frame  26  generally comprises a one-piece tube  40 . However, in alternate embodiments the frame could be comprised of more than one tube, such as multiple tubes connected in series, and could comprise additional members. The tube  40  is preferably comprised of a shape memory alloy material, such as Tinel or Nitinol. The shape memory alloy material is used for its superelastic properties exhibited by the material&#39;s ability to deflect and resiliently return to its natural or predetermined position even when material strains approach 4%, or an order of magnitude greater than the typical yield strain of 0.4% giving rise to plastic deformation in common metals. Thus, the term “superelastic alloy” is used to denote this type of material. The wire sheaths  50   a ,  50   b  may also be comprised of this type of material such as disclosed in U.S. Pat. No. 5,938,588 which is hereby incorporated by reference in its entirety. 
     The tube  40  has a center channel  42  with open front and rear ends  44 ,  45 , and slots  46  along at least part of its length. In this embodiment the slots have different patterns along different sections or lengths of the tube. More specifically, in this embodiment the slots  46 , are configured into three sections  52 , 54 ,  56 . Each section has a different pattern of the slots  46 . The pattern(s) of the slots  46  can be configured based upon, for example, the following variables: 
     distance or spacing between adjacent slots; 
     direction(s) of the slots into the tube  40 ; 
     depth of the slots into the tube; 
     width of the slots; 
     shape of the slots; and 
     intermixing of different directions of the slots along a length of the tube. 
     In alternate embodiments the tube  40  could have more or less than three sections of different slot patterns, such as only one or two. In addition, rather than abrupt transitions between sections of different slot patterns, the tube could be provided with gradual or intermixed slot transition zones between sections. In this embodiment the tube  40  also has two sections  58 ,  59  which do not have slots therein. 
     Referring also to FIGS. 4A and 4B, the first section  52  of the slots  46  is provided along the length of the active deflection section  18  of the shaft. In this embodiment the active deflection section  18  is two-way deflectable as shown by dotted lines in FIG.  1 . In alternate embodiments the active deflection section  18  could be merely one-way deflectable or more than two way deflectable. With the two way active deflection section  18  the frame is provided with two slot directions A and B into the side of the tube  40  which are 180° offset from each other. Referring also to FIG. 4C, the slots  46  have a depth Y into the tube  40 , but in opposite directions for the two types of slots  46   a ,  46   b  relative to the center axis  64  of the tube  40 . The slots have a centerline spacing X between adjacent slots  46   a ,  46   b . The slots  46   a ,  46   b  have a width W. In this embodiment the values for W, X and Y are the same along the length of the first section  52 . However, in alternate embodiments they could vary. Referring also to FIG. 5, a portion of the first section  52  is shown in a bent shape. The slots  46  provide the tube  40  with increased flexibility along the length of the first section  52 . In addition, the two directions A, B of the slots  46  in the first section  52  limit this increased flexibility to two opposite directions. The first section could have slots in only one direction for limited increased flexibility in only one direction or slots in four or more directions for four-way or omni-directional increased flexibility. 
     Referring to FIGS. 3 and 6 a - 6   d  the second section  54  is provided along the length of the passive deflection section  16  (see FIG.  1 ). However, the passive deflection section  16  need not have slots  46  in its length of the frame. In this embodiment the tube  40  is provided with slots  46   a ,  46   b ,  46   c  and  46   d  into the tube  40  in four directions A, B, C and D which are offset 90° from each other. The slots  46   a ,  46   b ,  46   c ,  46   d  are arranged in series in a repeating pattern, but any suitable intermixing of the pattern of the slots  46   a ,  46   b ,  46   c ,  46   d  could be provided. In this embodiment the distance X′ between adjacent slots  46  in the second section  54  is larger than the distance X between adjacent slots  46  in the first section  52 . However, any suitable spacing(s) could be provided for X′ including different spacings for X′ along the length of the second section  54 . Also in this embodiment the depth Y′ of the slots  46   a ,  46   b ,  46   c  and  46   d  in the second section  54  are less than depth Y in the first section  52 . In this embodiment the depth Y′ is about ½ the diameter of the tube  40  and the depth Y is about ⅔ the diameter of the tube  40 . However, Y and Y′ could have any suitable depths. In addition, Y′ could be different in different ones of the slots  46   a ,  46   b ,  46   c ,  46   d  along the length of the second section  54 , such as deeper towards the front of the tube. The widths of the slots  46   a ,  46   b ,  46   c  and  46   d  along the second section  54  could be the same as W for the first section  54 , could be different from the width W for the first section  52 , and/or could vary or be different along the length of the second section  54 , such as wider towards the front of the tube. The second section  54 , preferably has a larger column strength, larger stiffness (or less flexibility), and larger torque stability suitable for passive deflection rather than active deflection as the first section  52 . By providing the slots further apart from each other and with a shallower depth Y′, the second section  54  has a stronger column strength and torque stability than the first section  52 . The four directions A, B, C, D of the slots also provide four way deflection capability for the second section  54 , rather than merely two way deflection as in the first section, for better passive deflection capabilities. 
     The third section  56  of the tube  40  is provided between the second section  54  and the rear end non-slotted section  59 . However, in an alternate embodiment the third section need not have slots. In this embodiment the third section  56  extends along a majority of the length of the tube  40 . The pattern of slots  46  along the third section  56  has a different spacing X″, but is otherwise the same as the pattern of slots in the second section  54 . In an alternate embodiment the Y and W variables could be different, the directions of the slots  46  in the third section  56  could be different, and the distance X″ could vary along the length of the third section. FIGS. 7A-7E show one such variation wherein the third section  56 ′ of the tube  40  has slots  46  in five directions M, N, O, P, Q into the tube. The third section preferably has a higher column strength, stronger stiffness (or less flexibility), and stronger torque stability than the first and second sections  52 ,  54 . In this embodiment this is provided by providing the larger distance X″, but could alternatively be provided by any one or combination of the other variables that would effect column strength and torque stability. In the embodiment when the third section  56  does not have slots, the thickness of the wall of the tube would be selected to provide sufficient shaft flexibility without use of slots. Section  59  extends into the handle  12  and is fixedly connected to the frame of the handle. 
     Referring back to FIGS. 1-3, the cover  32  is preferably comprised of a resilient plastic or polymer material. The cover could also include a structural reinforcement, such as disclosed in U.S. patent application Ser. No. 09/087,305 filed May 29, 1998 entitled “Flexible Pressure Resistant Cover For The Articulation System Of A Medical Instrument” which is hereby incorporated by reference in its entirety. The cover  32  is preferably directly attached to the tube  40 , but not by adhesive. However, in alternate embodiments any suitable means could be used to attach the cover  32  to the tube  40  including use of adhesive. The cover  32  can be attached along the entire length of the tube  40  or can be attached at predetermined limited locations, such as being merely attached at sections  58 ,  59  and not attached anywhere else. Therefore, there may be lengths along the shaft  14  where the cover is able to move relative to the tube  40 . In the prior art adhesive was used in different thicknesses along the length of the shaft to provide different column strengths and shaft flexibility along the length of the shaft. A thicker amount of adhesive was used towards the rear of the shaft to make the column strength of the shaft stronger or stiffer at the rear of the shaft, but with the undesired problem that the rear of the shaft had a larger outer diameter than the front of the shaft. It is preferable to have a small outer diameter, such as when the endoscope is inserted through small apertures such as a patient&#39;s ureter or urethra. With the present invention, because the tube  40  provides sufficient column strength and stiffness, there is no need to increase column strength and stiffness by use of increased thickness of adhesive. Therefore, the shaft  14  can have a uniform outer diameter along its length. Thus, the thickness or outer dimension of the shaft is minimized. 
     In the prior art the objective head was attached to a deflection assembly and the deflection assembly was attached to a shaft assembly. The present invention allows an endoscope to be provided which does not have a separate active deflection assembly and a separate shaft assembly. Instead, the present invention allows the tube  40  to extend the entire length of the shaft with the single tube  40  performing functions that were previously preformed by the two assemblies in the prior art. By use of the single tube  40  the shaft  14  can be manufactured and assembled in less time and with less cost than in the prior art two assembly shaft and, can be more reliable because less parts are used, the superelastic alloy is more dependable, and there is less risk of failure or fatigue of the shaft  14  than in the prior art. The objective head  34  can be located inside the front end of the tube  40 ; the same tube which extends along the rest of the shaft and not merely along the active deflection assembly as in the prior art. 
     Tubes of superelastic alloy can be easily purchased from manufacturers at the present time. The tubes are presently manufactured with a uniform wall thickness, but it may be possible to vary the wall thickness along the length of the tube for different stiffness properties. However, tubes of superelastic alloy presently sold by manufacturers do not have slots in them. In order to manufacture the endoscope  10  the slots  46  need to be made into the tube of superelastic alloy. The tube can be purchased in precut lengths. One method of forming the slots  46  can comprise a laser cutting device. A laser of the device could cut the slots  46  into the solid tube with the device moving the tube and/or the laser. In a preferred embodiment, a programmable computer controller is used to control the device to form the slots  46  in the desired pattern(s) along the length of the tube. Thus, the pattern(s) can be selected or altered by appropriate computer programming to provide tubes with different slot patterns. These different types of tubes can be used to form endoscopes with different shaft properties, such as different stiffness properties along their lengths and different active deflection capabilities at their active deflection sections (one-way, two-way, four-way, etc.). In an alternate method wire electrical discharge machining (EDM) can be used to form the slots. However, any suitable method could be used to form the slots. 
     One of the advantages of the present invention is the ability to manufacture endoscopes with different shaft properties by providing tubes with different slot patterns, such as by merely having more or less slots  46  in the tube  40 . With this advantage a user can select an endoscope with a desired shaft stiffness configuration from a plurality of endoscopes with the endoscopes otherwise being virtually identical. The manufacturer could also custom build an endoscope with a desired shaft stiffness configuration for a user by merely reprogramming the slot forming device with an appropriate slot pattern. The present invention also allows a shaft to be disassembled and more slots added to the tube  40  to change shaft properties if desired. 
     Endoscopes need to be cleaned after their use. One method of cleaning involves gas sterilization and pressure reduction. A problem with gas sterilization is that pressure inside the shaft pushes outward when pressure outside the shaft is reduced. With endoscopes having vent valves, this is usually not a problem. However, vent valves increase the cost of the endoscope and, if a user forgets to open the vent valve during cleaning, the shaft cover can burst. There are endoscopes that do not have vent valves. Instead, they have reinforced covers. A reinforced cover, as mentioned in the patent application identified above, can overcome this burst problem. Another way to overcome this problem is to provide a thin wall strengthening tube inside the tube  40 . Referring also to FIG. 8, another way to overcome this problem is to provide the shaft  14 ′ with a multi-lumen tube  41  inside the area  42  of the tube  40 . The multi-lumen tube  41  can be comprised of a flexible polymer material and includes channels  70 ,  72 ,  74 ,  76  for the deflection control cables and fiber optics, as well as channel  78  which forms a working channel. The tube could also be a single lumen tube, such as the thin wall tube mentioned above. 
     It should be understood that the foregoing description is only illustrative of the invention. Various alternatives and modifications can be devised by those skilled in the art without departing from the invention. Accordingly, the present invention is intended to embrace all such alternatives, modifications and variances which fall within the scope of the appended claims.