Patent Publication Number: US-2010130823-A1

Title: Endoscope

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of Japanese Patent Application No. 2008-299450, filed Nov. 25, 2008, the entire contents of which are hereby incorporated by reference, the same as if set forth at length. 
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The invention relates to an endoscope in which an outer peripheral surface of a bendable portion provided on a distal end side of an endoscope insertion part is covered with an elastic tube having flexibility. 
     2. Description of the Related Art 
     An endoscope has an endoscope insertion part which is inserted into a body cavity or the like, and a operation part which is provided to be continued from a proximal end side of the endoscope insertion part. The endoscope insertion part is configured so that a distal end hard portion made of a hard member, a bendable portion which can be operated to be bent, and an introduction portion are continuously provided in this order from the distal end side. The distal end hard portion has a distal end portion body including an observation optical system for observing an inside of a body cavity, and a distal end sleeve which is fitted and fixed to the distal end portion body. A base end of the distal end sleeve is connected with the bendable portion. The bendable portion has a joint ring structure in which a number of joint rings are connected continuously and pivotally. The outer peripheries of the distal end hard portion and the bendable portion are covered with an elastic tube having flexibility, thereby airtightly holding the distal end hard portion and the bendable portion. 
     The above described elastic tube is fixed in two places of the distal end and base end thereof, and is not necessarily fixed in a range from the distal end to the base end. Therefore, for example, when dirt adhered to the endoscope insertion part is wiped and cleaned after endoscopic examination, the elastic tube may be pulled to the distal end due to the load (squeeze, etc.) applied during the cleaning, and deviation and loosening may occur in the elastic tube. Once the elastic tube is loosened, the tube does not naturally return to its original state even if the load is released. If the loosening exists, the elastic tube which has been pulled in the longitudinal direction may be folded back, and may be covered on the distal end. As a result, a diameter of the distal end becomes locally large, and it may become difficult to smoothly move the endoscope insertion part within the body cavity. 
     JP Sho 58-49132 A describes a technique regarding an endoscope having a first bendable portion which is bent by a bending operation performed by an operation part, and a second bendable portion which is bent only by an external force. In this endoscope, loosening of the elastic tube is prevented by fixing a portion of the elastic tube (angle rubber) at a boundary portion between the first bendable portion and the second bendable portion. 
     However, there is a disadvantage that a step portion (height difference) is caused as the elastic tube is fixed at the boundary portion between the first bendable portion and the second bendable portion, and the diameter of the endoscope insertion part increases due to this step portion. Additionally, it is necessary to provide a recess at the boundary portion so that the elastic tube does not deviate. Due to this recess, there is a disadvantage that the internal diameter of the bendable portion is forced to be small, and a section area used to house conduits or the like is reduced. 
     SUMMARY OF THE INVENTION 
     The invention has been made in view of the above circumstances, and provides an endoscope which can prevent deviation and loosening of an elastic tube covering an outer periphery of a bendable portion of an endoscope insertion part. 
     According to an aspect of the invention, an endoscope includes an endoscope insertion part, a bendable portion and an elastic tube. The bendable portion is configured to be operated to be bent within one plane which is parallel to an axial direction of the endoscope insertion part. The bendable portion is disposed on a distal end side of the endoscope insertion part. The elastic tube has flexibility and covers an outer peripheral surface of the bendable portion. A rigidity of the elastic tube in directions orthogonal to bending operation directions is higher than that of the elastic tube in the bending operation directions. 
     With the above endoscope, it is possible to prevent deviation and loosening of the elastic tube covering the outer periphery of the bendable portion of the endoscope insertion part. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an appearance perspective view of an endoscope according to an embodiment of the invention. 
         FIG. 2  is a section view showing a bendable portion of  FIG. 1  taken along a line A-A in a state where a housed object is omitted. 
         FIG. 3  is a conceptual diagram showing a bendable tube structure. 
         FIG. 4A  is a perspective view of an angle rubber alone. 
         FIG. 4B  is a section view taken along a line B-B. 
         FIG. 5  is an explanatory view conceptually showing a state where the bendable portion is bent. 
         FIG. 6A  is a section view of the angle rubber equivalent to the section B-B of  FIG. 4A . 
         FIG. 6B  is a section view showing the bendable portion when the angle rubber covers the insertion part of the endoscope, in a state where a housed object is omitted. 
         FIG. 7A  is a section view of the angle rubber equivalent to the section B-B of  FIG. 4A . 
         FIG. 7B  is a section view showing the bendable portion when the angle rubber covers the insertion part of the endoscope, in a state where a housed object is omitted. 
         FIG. 8A  is a section view of the angle rubber equivalent to the section B-B of  FIG. 4A   
         FIG. 8B  is a section view showing the bendable portion when the angle rubber covers the insertion part of the endoscope, in a state where a housed object is omitted. 
         FIG. 9A  is a section view of the angle rubber equivalent to the section B-B of  FIG. 4A . 
         FIG. 9B  is a section view showing the bendable portion when the angle rubber covers the insertion part of the endoscope, in a state where a housed object is omitted. 
         FIG. 10  is a section view showing the bendable portion when the angle rubber in which a hard portion is made thin covers the insertion part of the endoscope, in a state where a housed object is omitted. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION 
     Hereinafter, an endoscope will be described in detail with reference to the drawings. 
       FIG. 1  is an appearance perspective view of the endoscope for explaining the embodiment of the invention. 
     The endoscope  100  of this configuration mainly has a operation part  11 , and an endoscope insertion part  13  which extends to the operation part  11 . The endoscope insertion part  13  includes channel holes, various types of conduits, etc. therein. A light guide (LG) flexible part  15  is connected to the operation part  11 . The light guide flexible part  15  is connected to a processor provided with a light source and a signal processor (which are not shown). 
     The operation part  11  is provided with a forceps opening  17  into which treatment tools, such as forceps, are inserted. The operation part  11  is also provided with a switch  19  which is used to fetch an image and to switch among functions, an upper and lower angle lever  21  and a suction button  23 . 
     The endoscope insertion part  13  includes a soft portion  25 , a bendable portion  27 , and a distal end portion  29  in order from a proximal end side which is continued to the operation part  11 . The bendable portion  27  located on the distal end side of the endoscope insertion part  13  is remotely operated to be bent, by operating the upper and lower angle lever  21  provided in the operation part  11 , to thereby direct the distal end portion  29  toward a desired direction. That is, the bendable portion  27  is operated to be bent in a plane which is parallel to the axial direction of the endoscope insertion part  13 . Also, the outer peripheral surfaces of the bendable portion  27  and the distal end portion  29  are covered with an elastic tube (hereinafter referred to as an “angle rubber”)  31  having flexibility. 
       FIG. 2  is a section view showing a section of the bendable portion of  FIG. 1  taken along a line A-A, in a state where a housed object is omitted. 
     The bendable portion  27  has a bendable tube structure in which a plurality of ring-shaped joint rings  35 , each formed with connecting portions  33  on sides orthogonal to the bending operation directions U and D, are juxtaposed along the axial direction of the endoscope insertion part  13 , and adjacent joint rings  35  are rotatably connected to each other by the connecting portions  33 .  FIG. 3  shows this bendable tube structure. 
     The bendable portion  27  is configured so that the plurality of joint rings  35  formed in a ring shape are continuously pivoted in the axial direction. In adjacent joint rings  35 , their connecting portions  33  are overlapped with each other, and then, caulking pins  37  are inserted into through holes provided in the connecting portions  33 , and the outsides of the caulking pins  37  are caulked. Thereby, the respective joint rings  35  are rotatably connected together. 
     Among the joint rings  35 , which are continuously pivoted, a joint ring  35 A on the most distal end side is formed to be longer in the axial direction. A distal end hard portion  39  made of ceramics or the like is joined to the distal end side, in the axial direction, of the joint ring  35 A. Also, a tubular net  43  made of braided metal wire or the like is mounted on the outsides of the joint rings  35  via lubricant. As shown in  FIG. 2 , the outer periphery of the net  43  is covered with the angle rubber  31 . The tip of the net  43  is fixed to the outer periphery of the joint ring  35 A on the distal end side. A cylindrical sleeve may be interposed between the joint ring  35 A on the distal end side and the distal end hard portion  39 . 
     Inside the joint rings  35 , a pair of upper and lower control wires  41  is disposed along the axial direction of the inner peripheral surface thereof. The tips of the control wires  41  and  41  are fixed to the joint ring  35 A on the most distal end side. The base ends of the control wires  41  and  41  are connected to pulleys (not shown) rotated by the upper and lower angle lever  21  (see  FIG. 1 ) of the operation part  11 . With this configuration, when the upper and lower angle lever  21  is operated to rotate the pulleys, any one of the control wires  41  and  41  is pulled, and the bendable portion  27  is bent in a desired direction. 
     The angle rubber  31  is a covering member which covers the outer peripheries of the distal end portion  29  and the bendable portion  27  (see  FIG. 1 ), and is made of an elastic material having flexibility. The angle rubber  31  can be formed from, for example, rubber having fluorine as its material. The tip of the angle rubber  31  is fixed, for example, by causing the tip to abut against the distal end hard portion  39  beyond the joint ring  35 A on the distal end side, firmly winding a thread around the outer periphery of the angle rubber  31  in a position of a thread-winding portion  39   a  formed in the distal end hard portion  39 , and applying an adhesive or the like thereto. The base end of the angle rubber  31  is fixed to the base end of the bendable portion  27 . By fixed the both ends of the angle rubber  31  in this manner, the inside of the angle rubber  31  is airtightly kept. 
       FIG. 4A  is a perspective view of the angle rubber alone, and  FIG. 4B  is a section view taken along a line B-B. 
     The angle rubber  31  is cylindrical as a whole and is formed with, in the inner peripheral surface thereof, thick-walled portions  45  in directions L and R orthogonal to the bending operation directions U and D. By forming the wall thicknesses of the angle rubber  31  in circumferential positions of the angle rubber  31  in the directions L and R orthogonal to the bending operation directions U and D to be larger than those of the angle rubber  31  in circumferential positions of the angle rubber  31  in the bending operation directions U and D in this manner, the rigidity of the angle rubber  31  in the directions L and R orthogonal to the bending operation directions is higher than that of the angle rubber  31  in the bending operation directions U and D. 
     Here, the angle rubber  31  shown in  FIG. 4  is aligned with and put on the endoscope insertion part  13  so that the thick-walled portions  45  are located in the circumferential positions of the angle rubber  31  where the thick-walled portions  45  face the connecting portions  33 . Then, as shown in  FIG. 2 , the angle rubber  31  covers the endoscope insertion part  13  in a state where the thick-walled portions  45  protrude toward the outer peripheral side. The existence of the thick-walled portions  45  provides the following effects. That is, the angle rubber  31  is prevented from being pulled to the distal end portion due to a load applied at the time of cleaning when dirt adhered to the endoscope insertion part  13  after endoscopic examination is wiped and cleaned, and deviation and loosening of the angle rubber  31  hardly occur. Moreover, when the bendable portion  27  shown in  FIG. 5  is bent, the thick-walled portions  45  are located on the neutral axis of bending displacement. Therefore, bending rigidity does not increase due to the thick-walled portions  45  of the angle rubber  31 , to adversely affect the bending operation. Also, the thick-walled portions  45  of the angle rubber  31  are continuously formed along the insertion direction of the endoscope insertion part  13 , and are projections which are smooth even in a peripheral direction. Therefore, a stepped portion accompanied by the insertion operation does not influence the thick-walled portions  45 . 
     As described above, deviation and loosening of the angle rubber  31  are prevented by making the rigidity of the angle rubber  31  in the circumferential positions of the angle rubber  31  in the directions L and R orthogonal to the bending operation directions U and D to be higher than that of the angle rubber  31  in the circumferential positions of the angle rubber  31  in the bending operation directions U and D. With this configuration, it is possible to smoothly move the endoscope insertion part  13  within a body cavity, and smooth endoscopy can be always stably carried out. 
     Next, another example of the above angle rubber  31  will be described. 
       FIG. 6A  is a section view of the angle rubber equivalent to the section B-B of  FIG. 4A , and  FIG. 6B  is a section view showing the bendable portion when the angle rubber covers the insertion part of the endoscope, in a state where a housed object is omitted. In the angle rubber  31 A of this example, the wall thicknesses of the angle rubber  31 A in circumferential positions of the angle rubber  31 A in the directions L and R orthogonal to the bending operation directions U and D is larger than those in circumferential positions of the angle rubber  31 A in the bending operation directions U and D. Also, the wall thicknesses of the angle rubber  31 A in circumferential positions of the angle rubber  31 A which face the connecting portions  33  are smaller than those on both sides of the circumferential positions of the angle rubber  31 A which face the connecting portions  33 . That is, thick-walled portions  47  are formed on the both sides of the circumferential positions of the angle rubber  31 A which face the connecting portions  33  in the orthogonal directions L and R so that an average wall thicknesses in the circumferential positions of the angle rubber  31 A in the orthogonal directions L and R are larger than those in the circumferential positions of the angle rubber  31 A in the bending operation directions U and D. Also, the circumferential positions of the angle rubber  31 A which face the connecting portions  33  are thinner than the thick-walled portions  47 . When the angle rubber  31 A of this configuration is aligned with and put on the endoscope insertion part  13  so that the thick-walled portions  47  are located in circumferential positions which sandwich the connecting portions  33 , as shown in  FIG. 6B , the outermost diameter of the endoscope insertion part  13  in the circumferential positions corresponding to the connecting portions  33  can be made smaller than that of the aforementioned example shown in  FIG. 2 . Also, the “wall thickness in the circumferential positions in the above orthogonal directions L and R” may mean an average thickness (including the thick-walled portions  47 ) of the angle rubber  31 A in the orthogonal directions L and R within a predetermined circumferential length. 
     In the above configuration, with regard to protruding portions of the caulking pins  37  in the connecting portions  33 , the protruding portions can be housed by forming the thick-walled portions  47  of the angle rubber  31 A to be partially thin. This suppresses an increase in the external diameter of the endoscope insertion part  13  while preventing the loosening of the angle rubber  31 A. 
     Next, further another example of the angle rubber  31  will be described. 
       FIG. 7A  is a section view of the angle rubber equivalent to the section B-B of  FIG. 4A , and  FIG. 7B  is a section view showing the bendable portion when the angle rubber covers the insertion part of the endoscope, in a state where a housed object is omitted. In the angle rubber  31 B in this case, wires  49  are buried along the axial direction of the endoscope insertion part  13  in the angle rubber  31 B in the circumferential positions of the angle rubber  31 B in the directions L and R orthogonal to the bending operation directions U and D. Although not shown, both ends of the wires  49  are fixed to the angle rubber  31 B. By arranging the wires  49  in the angle rubber  31 B in the circumferential positions corresponding to the connecting portions  33 , the rigidity of the angle rubber  31 B in circumferential positions of the angle rubber in the directions orthogonal to the bending operation directions is higher than that in circumferential positions of the angle rubber  31 B in the bending operation directions of the angle rubber  31 B. As a result, deviation and loosening of the angle rubber  31 B are prevented from occurring. Moreover, since there is no thick-walled portion in the bending operation direction of the angle rubber  31 B, and the wires  49  exist on the neutral axis of the bending operation, the bending operation is not adversely affected. Additionally, the durability of the angle rubber  31 B itself can be improved by integrally forming the hard wires  49 . 
     In the illustrated example, the wires  49  are arranged in the circumferential positions of the angle rubber  31 B in the directions L and R orthogonal to the bending operation directions U and D, respectively. However, the invention is not limited thereto. A plurality of wires (the number of wires being arbitral) may be provided. For example, by burying a plurality of wires in regions which face the caulking pins  37 , the angle rubber  31   b  can be reinforced so that a portion where an external force becomes apt to be concentrated is covered by the protrusion of the caulking pins  37 , and durability can be further improved. If the section shape of the wires  49  is formed in a rectangular shape other than a circular shape, a region where rigidity becomes high can be expanded in the peripheral direction of the angle rubber  31 B, and the durability of the angle rubber  31 B is further improved. 
     Still further another configuration example in which wires are buried within the thick-walled portions of the angle rubber is shown in  FIGS. 8A and 8B . 
       FIG. 8A  is a section view of the angle rubber equivalent to the section B-B of  FIG. 4A .  FIG. 8B  is a section view showing the bendable portion when the angle rubber covers the insertion part of the endoscope in a state where a housed object is omitted. The angle rubber  31 C of this example is configured so that wires  49  are respectively buried in thick-walled portions  47  of the angle rubber  31 A shown in  FIGS. 6A and 6B . 
     In this case, a plurality of wires  49  are respectively arranged in circumferential positions of the angle rubber  31 C in the directions L and R orthogonal to the bending operation directions U and D of the angle rubber  31 C. Therefore, the resistance of the angle rubber  31 C against twist in the axial direction becomes high, and loosening can be made less likely to occur. 
     Next, still further another example of the angle rubber will be described. 
       FIG. 9A  is a section view of the angle rubber equivalent to the section B-B of  FIG. 4A .  FIG. 9B  is a section view showing the bendable portion when the angle rubber covers the insertion part of the endoscope, in a state where a housed object is omitted. The angle rubber  31 D of this example is configured so that portions in the circumferential positions of the angle rubber  31 D in the directions L and R orthogonal to the bending operation directions U and D are formed from an elastic material having a larger elastic constant than that of portions of the angle rubber  31 D in the other circumferential positions. That is, the angle rubber  31 D is formed from materials having elastic constants which are different from each other, in the circumferential positions of the angle rubber  31 D in the bending operation directions U and D and in the circumferential positions of the angle rubber  31 D in the orthogonal directions L and R. The angle rubber  31 D includes hard portions  51  in the circumferential positions of the angle rubber  31 D in the orthogonal directions L and R. The hard portions  51  may be formed from a harder rubber material or the like than in the other circumferential positions of the angle rubber  31 D. The angle rubber  31 D having such hard portions  51  can be efficiently molded by, for example, processing methods, such as multi-color extrusion molding which simultaneously extrudes and molds elastic materials having mutually different elastic constants, or a combined extrusion molding of manufacturing hard portions  51  in advance and extrudes and molding the hard portions  51  from a softer elastic material. 
     According to the angle rubber  31 D, the rigidity can be changed while the radial thickness is kept constant. The angle rubber  31 D can be processed at low cost while productivity is increased by suppressing the amount of raw material to a required minimum. In the case where the hard portions  51  which are molded in advance are insert-molded as in the above combined extrusion molding, local processing of the hard portions  51 , such as forming recesses which house the protruding caulking pins  37  in the inner peripheral surface, can be simply performed. 
     Moreover, by making hard portions  51 A thinner than the other portions like an angle rubber  31 E shown in  FIG. 10 , protruding of the caulking pins  37  in the connecting portions  33  can be prevented from becoming higher than the other circumferential positions. 
     As described above, the following matters are described in this specification. 
     (1) An endoscope includes an endoscope insertion part, a bendable portion and an elastic tube. The bendable portion is configured to be operated to be bent within one plane which is parallel to an axial direction of the endoscope insertion part. The bendable portion is disposed on a distal end side of the endoscope insertion part. The elastic tube has flexibility and covers an outer peripheral surface of the bendable portion. A rigidity of the elastic tube in directions orthogonal to bending operation directions is higher than that of the elastic tube in the bending operation directions. 
     With this endoscope, occurrence of deviation and loosening of the elastic tube can be prevented, and the bending operation is not adversely affected while the bending operation can be operated with a small load. 
     (2) In the endoscope of (1), wall thicknesses of the elastic tube in circumferential positions of the elastic tube in the directions orthogonal to the bending operation directions may be larger than those of the elastic tube in circumferential positions of the elastic tube in the bending operation directions. 
     With this endoscope, the rigidity of the elastic tube can be easily adjusted with a high degree of freedom by varying wall thicknesses of the elastic tube. Also, the durability of the elastic tube is improved by the existence of a portion whose wall thickness is large. 
     (3) In the endoscope of any one of (1) to (2), wires may be buried along the axial direction in the elastic tube in circumferential positions of the elastic tube in the directions orthogonal to the bending operation directions. 
     With this endoscope, the rigidity of the elastic tube is increased by burying the wires without great increase in diameter of the endoscope insertion part. 
     (4) In the endoscope of (2), the bendable portion may have a bendable tube structure. In the bendable structure, a plurality of ring-shaped joint rings each formed with connecting portions in circumferential positions thereof in the directions orthogonal to the bending operation directions are juxtaposed along the axial direction, and adjacent joint rings are rotatably connected to each other by the connecting portions. The wall thicknesses of the elastic tube in the circumferential positions of the elastic tube which face the connecting portions may be smaller than those of the elastic tube on both sides of the circumferential positions of the elastic tube which face the connecting portions. 
     With this endoscope, the protruding height of the elastic tube to the outside can be suppressed to be low by making the elastic tube be thin in the connecting portions which protrude in the axial direction. 
     (5) In the endoscope of (4), wires may be buried along the axial direction in thick-walled portions of the elastic tube on the both sides of the circumferential positions of the elastic tube which face the connecting portions. 
     With this endoscope, the wires are arranged on the both sides sandwiching the connecting portions by burying the wires in the thick-walled portions, respectively. Thus, the strength of the endoscope insertion part against twist in the axial direction increases, and the durability improves. Additionally, the wires can be arranged with space efficiency being enhanced. 
     (6) In the endoscope of (1), the circumferential positions of the elastic tube in the directions orthogonal to the bending operation directions may be formed from an elastic material having a larger elastic constant than other circumferential positions of the elastic tube. 
     With this endoscope, the angle rubber can be processed at low cost while productivity is increased by suppressing the amount of raw material to a required minimum. 
     The above description on the embodiments of the invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention thereto. Various modifications will be apparent to one skilled in the art.