Patent Publication Number: US-2010113879-A1

Title: Endoscope and flexible tube thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority under 35 USC 119 from Japanese Patent Application No. 2008-285005 filed on Nov. 6, 2008, the disclosure of which is incorporated by reference herein. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an endoscope and flexible tube thereof. 
     2. Description of the Related Art 
     Medical endoscopes are used for inserting the insertion section thereof into a body cavity when observing internal organs and the like, and various types of treatment and procedures are performed by employing treatment instruments that are inserted into treatment instrument insertion channels of endoscopes. Consequently, when an endoscope that has been used once is to be reused on another patient, disinfection and sterilization of the endoscope must be performed after finishing the investigation or treatment in order to prevent contagion between patients via the endoscope. Disinfectant liquids, ethylene oxide gas, formalin gas, hydrogen peroxide gas plasma, ozone, or autoclaves that sterilize using high temperature and pressure steam are employed as methods for disinfection and sterilization. 
     Autoclaves that sterilize endoscopes with high temperature and pressure steam have already become widely used globally as a disinfection and sterilization method. This method has several merits, such as a highly reliable sterilization effect, no residual toxicity, cheap running cost, and the like. In American Standard ANSI/AAMI ST37-1992, issued by the Association for the Advancement of Medical Instrumentation and endorsed by the American National Standards Institute, typical conditions during high temperature and pressure steam sterilizing of endoscopes are four minutes at 132° C. for a pre-vacuum sterilization process and 10 minutes at 132° C. for a gravity sterilization process. However, there is the problem that great damage is imparted to medical instrumentation under such conditions. 
     Flexible tubes for endoscopes are equipped with helical tubes formed from a strip shaped member wound in a helical shape at a constant diameter, a mesh tube formed of fine wires braided into a ring shape around the outer periphery of the helical tube, and an external skin member that covers the outer periphery of the mesh tube. In particular, an endoscope flexible tube whose surface is covered by an external skin is proposed (see Japanese Patent Application Laid-Open (JP-A) Nos. 2006-314521 and 2006-25843) as an endoscope flexible tube with excellent chemical liquid durability and autoclave durability, the external skin thereof being configured from a polyolefin thermoplastic elastomer. 
     However, in the configuration of the flexible tube described in JP-A Nos. 2006-314521 and 2006-25843, a problem arises that the insertability of the flexible tube deteriorates due to the occurrence of thermal deformation when processing in an autoclave in a bent state. 
     SUMMARY OF THE INVENTION 
     In consideration of the above circumstances, the present invention provides a flexible tube for an endoscope that is not readily imparted with a permanent or semi-permanent curvature even when autoclave processing. 
     A first aspect of the present invention is a flexible tube for an endoscope, the flexible tube including: a helical tube formed with a strip shaped member wound in a helical shape; a mesh tube, disposed at the outer periphery of the helical tube and formed in a ring shape from braided fine wires; a thermoplastic resin, disposed at the outer periphery of the mesh tube and formed in a patterned shape; and an outer skin disposed at the outer periphery of the mesh tube at which is formed the thermoplastic resin, the outer skin being formed from a material having a smaller thermal deformation than the thermoplastic resin. 
     According to the above configuration, the thermoplastic resin formed at the outer periphery of the mesh tube is formed in a patterned shape, and the outer skin at the outer periphery of the mesh tube at which is formed the thermoplastic resin is formed from a material having a smaller thermal deformation than the thermoplastic resin. 
     Consequently, the flexible tube of the endoscope is not readily thermally deformed and is not readily imparted with a permanent or semi-permanent curvature when processed in an autoclave. 
     In the endoscope flexible tube of the first aspect of the present invention, the thermoplastic resin may be formed into plural ring shapes running in the circumferential direction of the mesh tube, or may be formed in a helical shape wound in the circumferential direction of the mesh tube. 
     By adopting such a configuration, the thermoplastic resin is readily formed in a patterned shape since the thermoplastic resin is formed into plural ring shapes running in the circumferential direction of the mesh tube, or in a helical shape wound in the circumferential direction of the mesh tube. 
     In the endoscope flexible tube of the first aspect of the present invention, the outer skin may be made from a fluoro-rubber or from a silicone-rubber. 
     By adopting such a configuration the flexible tube of the endoscope is not readily thermally deformed and is not readily imparted with a permanent or semi-permanent curvature when processed in an autoclave since the outer skin is made from a fluoro-rubber or from a silicone-rubber, these having durability to high temperature and pressure steam (durability when autoclave processed). 
     Since the above configuration is adopted the present invention can be made not readily imparted with a permanent or semi-permanent curvature even when processed in an autoclave. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the present invention will be described in detail based on the following figures, wherein: 
         FIG. 1  is a schematic configuration diagram illustrating an endoscope according to the present exemplary embodiment; 
         FIG. 2  is a partially cut-away side view illustrating the configuration of a flexible tube for an endoscope according to the present exemplary embodiment; 
         FIG. 3  is a cross-section illustrating a configuration of a flexible tube for an endoscope according to the present exemplary embodiment; 
         FIG. 4  is a partially cut-away perspective view illustrating a configuration of a flexible tube for an endoscope according to the present exemplary embodiment; 
         FIG. 5  is a partially cut-away side view illustrating the configuration of a flexible tube for an endoscope according to an exemplary modification with thermoplastic resin formed into a helical shape; 
         FIG. 6  is a schematic diagram illustrating a method for forming the thermoplastic resin according to the present exemplary embodiment; and 
         FIG. 7  is a schematic diagram illustrating another method for forming the thermoplastic resin according to the present exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     An example of an exemplary embodiment of the present invention will now be described with reference to the drawings. 
     Explanation will first be given of the overall configuration of an endoscope  10  according to the present exemplary embodiment.  FIG. 1  is diagram illustrating the overall configuration of an endoscope  10  according to the present exemplary embodiment. 
     The endoscope  10  according to the present exemplary embodiment, as shown in  FIG. 1 , is provided with an elongated shaped insertion section  12  that is inserted into a body cavity of a patient, and a main body manipulation section  14  is connected to an end portion of the insertion section  12 . An elongated shaped light guide flexible section  16  is connected to the main body manipulation section  14 , the light guide flexible section  16  being detachably connectable to a light source device (not shown in the figures). A connection section  18  equipped with terminal(s) for connection to the light source device (not shown in the figures) is provided at the distal end of the light guide flexible section  16 . A manipulation knob  20  for manipulating the insertion section  12  is provided to the main body manipulation section  14 . 
     The insertion section  12  is equipped with: a flexible tube  12 A, which makes up most of the length in the longitudinal direction (axial direction) of the insertion section  12 , from a connection section thereof to the main body manipulation section  14 ; an angle section  12 B connected to the longitudinal direction distal end side of the flexible tube  12 A; and a distal end portion main body  12 C connected to the longitudinal direction distal end side of the angle section  12 B and internally installed with an object optical system and the like. 
     The angle section  12 B is configured so as to remotely bendable by rotational manipulation of the manipulation knob  20  provided to the insertion section  12 . The light guide flexible section  16  is also of substantially the same structure as the flexible tube  12 A of the insertion section  12 . 
     The flexible tube  12 A is set with a length that ensures the distal end portion main body  12 C can reach the inside of a specific portion subject to observation, and is a length that an operator can grip the main body manipulation section  14  and operate away from the patient or the like without difficulty. The flexible tube  12 A needs to have some flexibility over the substantially the entire length thereof, with locations thereof that are inserted into the body cavity or the like of a patient being of a structure that is particularly more flexible. 
     The flexible tube  12 A, particularly at the portion thereof connected to the main body manipulation section  14 , needs to have a certain rigidity to bending (flexural rigidity) in order to obtain insertion propulsion force when inserting into a body cavity or the like. In particular the flexible tube  12 A preferably has greater flexibility at the portion thereof connected to the angle section  12 B in order to be able to substantially follow the bent shape of the angle section  12 B when the angle section  12 B is bent. 
     While not illustrated in the figures, the flexible tube  12 A is internally mounted with a light guide, image guide (signal cable in the case of an electronic endoscope), treatment instrument insertion channel, gas and liquid transmission tube, and the like. 
     A partially cut-away side view of the flexible tube  12 A is illustrated in  FIG. 2 . A cross-section of the flexible tube  12 A is illustrated in  FIG. 3 , and a partially cut-away perspective view of the flexible tube  12 A is illustrated in  FIG. 4 . As shown in these figures, the flexible tube  12 A is equipped with: a helical tube  32  shaped (formed) from a metal strip shaped member wound into a helical shape; a mesh tube  34  shaped (formed) in a ring shape of braided fine wires (wire material) made from a metal at the outer periphery of the helical tube  32 ; a thermoplastic resin  35  formed at the outer periphery of the mesh tube  34 ; and an external skin  36  formed at the outer periphery of the mesh tube  34  at which is formed the thermoplastic resin  35 . 
     The external skin  36  employs a material that has a thermal deformation (residual deformation when returned to room temperature) at least less than that of the thermoplastic resin  35 , and, for example, is formed from a fluoro-rubber or silicone-rubber material. 
     A fluoro- or silicone-rubber has durability to high temperature and pressure steam (durability when autoclave processed), however the bending rigidity is less than that of the thermoplastic resin  35 . 
     The thermoplastic resin  35  is directly formed with a patterned shape at the outer periphery of the mesh tube  34 . The patterned shape is such that there are plural portions on the outer periphery of the mesh tube  34  formed with the thermoplastic resin  35 , and plural portions thereon not formed with the thermoplastic resin  35 . 
     In the present exemplary embodiment, specifically, the patterned shape is not linearly continuous in the longitudinal direction of the flexible tube  12 A, namely, the thermoplastic resin  35  is intermittently present when viewed in a straight line along the longitudinal direction of the flexible tube  12 A, with portions formed with the thermoplastic resin  35  and portions not formed with the thermoplastic resin  35 . 
     More specifically, as shown in  FIGS. 2 ,  3 , and  4 , patterned shape of the thermoplastic resin  35  is in plural ring shapes formed separated at specific intervals and running in the circumferential direction of the mesh tube  34 . 
     Also, the thermoplastic resin  35  functions as an adhesive for joining the external skin  36  to the mesh tube  34 . The thermoplastic resin  35  has conjugative ability to each of the mesh tube  34  and the external skin  36  that is at least higher than the conjugative ability of the external skin  36  to the mesh tube  34 , thereby raising the conjugative ability between the external skin  36  and the mesh tube  34 . 
     Specifically, another elastomer, such as, for example, a polyamide elastomer, a fluoro-elastomer, a styrene elastomer, a polyester elastomer, or a polyurethane elastomer, is employable as the thermoplastic resin  35  in place of an olefin elastomer, such as a polypropylene resin, an ethylene-propylene copolymer resin, or the like. 
     It should be noted that the thermoplastic resin  35  is not limited to being formed with the ring shaped patterned shape as illustrated in  FIGS. 2 ,  3 , and  4 , as long as a patterned shape is formed so as to partially cover the peripheral face of the mesh tube. As the patterned shape various shapes may be envisaged, such as a striped shape, a zigzag shape, or the like, for example a spiral shape may be made, as shown in  FIG. 5 , wound in the circumferential direction of the mesh tube  34 . 
     Explanation will now be give on an example of a forming method of the external skin  36 . 
     First the thermoplastic resin  35  is applied to the outer periphery of the mesh tube  34 . Specifically, as shown in  FIG. 6 , the mesh tube  34  is rotated in the circumferential direction thereof by a rotation unit, and after rotating the mesh tube  34  and applying a silane coupling agent thereto, an extrusion device  102  is moved along the longitudinal direction of the mesh tube  34 , and the thermoplastic resin  35  is extruded from a nozzle in the extrusion device  102  and coated. Rotating the mesh tube  34  enables a patterned shape to be formed in a ring shape, a helical shape, or a stripe shape. The temperature of the thermoplastic resin  35  when so doing exceeds the melting point thereof. 
     The coating width and thickness of the thermoplastic resin  35  can be controlled by varying the shape of the nozzle of the extrusion device  102 . The cover ratio of the thermoplastic resin  35  can be controlled by the extrusion pressure. 
     In order to suppress thermal deformation of the flexible tube  12 A the cover ratio of the surface of the mesh tube  34  is preferably 80% or less. In order to ensure adhesive strength to the external skin  36  the cover ratio of the surface of the mesh tube  34  is preferably 20% or greater. 
     From the standpoint of suppressing thermal deformation, the coating width is preferably about 2 to 3 mm, and from the standpoint of suppressing undulations the coating thickness is preferably about 0.1 mm or less. 
     It should be noted that the configuration for applying the thermoplastic resin  35  is not limited to a method using the extrusion device  102 , and various methods may be employed. For example, as shown in  FIG. 7 , thermoplastic resin  35  dissolved in a solvent may be ejected and applied from an ejection heat  104 . 
     The external skin  36  made from a fluoro-rubber is then formed onto the outer periphery of the mesh tube  34  at which is formed the thermoplastic resin  35 . The external skin  36  is vulcanize bonded at high temperature onto both the mesh tube  34  and the thermoplastic resin  35  using a primer. 
     According to the flexible tube  12 A of the endoscope  10  of the present exemplary embodiment as described above, the thermoplastic resin  35  formed onto the outer periphery of the mesh tube  34  is in a patterned shape, and also the external skin  36  formed onto the outer periphery of the mesh tube  34  at which is formed the thermoplastic resin  35  is made from a material having a smaller thermal deformation than the thermoplastic resin  35 . 
     Consequently, the flexible tube  12 A of the endoscope  10  is not readily thermally deformed and not readily imparted with a permanent or semi-permanent curvature when autoclave processing. 
     Since the external skin  36  is fusion bonded to the mesh tube  34  through the thermoplastic resin  35  without employing an adhesive, the external skin  36  does not readily separate from the mesh tube  34  even when subjected to repeated autoclave processing. 
     The rigidity to bending (flexural rigidity) of the flexible tube  12 A can be adjusted to a specific value by varying the density and pitch of the pattern of the thermoplastic resin  35 . The rigidity to bending of the flexible tube  12 A can be adjusted to specific values at locations in the longitudinal direction thereof by varying the density and pitch of the pattern of the thermoplastic resin  35  at locations in the longitudinal direction (axial direction). For example, at locations of the flexible tube  12 A that are near to the main body manipulation section  14  the rigidity to bending can be raised in order to obtain insertion propulsion force when inserting into a body cavity or the like. In addition, for example, the rigidity to bending of the portion of the flexible tube  12 A near to the angle section  12 B can be made lower than that of the portions near to the main body manipulation section  14  in order to be able to substantially follow the bent shape of the angle section  12 B when the angle section  12 B is bent. 
     The present invention is not limited to the above exemplary embodiment, and various changes, modifications and improvements are possible thereto.