JP5331424B2 - Endoscope - Google Patents

Description

  The present invention relates to an endoscope in which a forceps channel and other built-in components are inserted through an insertion portion to be inserted into a body cavity.

  An endoscope is known as a medical device used for inspection and treatment in a body cavity of a living body. The endoscope includes an insertion portion that is inserted into a body cavity and an operation portion that is provided at the proximal end of the insertion portion. The insertion part is an elongated hollow rod-like body having a diameter of several millimeters and a length of several tens of centimeters to several meters, and a distal end side is provided with a bending part that freely changes the direction of the distal end of the insertion part. .

  The bending portion has a structure in which a plurality of cylindrical bending pieces are connected so as to be rotatable with respect to each other so as to be bent. Inside each bending piece, for example, four wire guides through which the operation wires are inserted are provided along the circumferential direction. The bending portion bends up and down and left and right as the operation wire is pushed and pulled by the operation portion, and directs the hard portion in a desired direction.

  Built-in objects such as a forceps channel, an air / water supply channel, and a light guide are inserted into the insertion portion. The forceps channel is a flexible tube inserted up to the operation unit, and causes the treatment tool inserted from the operation unit to protrude from the distal end of the insertion unit. The air / water supply channel is a flexible tube inserted from the operation unit to the distal end of the insertion unit, and supplies water and air for cleaning an imaging window used for imaging in the body cavity. The light guide is composed of a plurality of optical fibers whose one end faces an illumination window provided at the distal end of the insertion portion, and guides the light emitted from the light source to illuminate the inside of the body cavity.

  A transnasal type upper endoscope has been marketed in which the outer diameter of the insertion portion is made thinner than that of an oral type endoscope (for example, 6 mm or less) and can be inserted from the nostril. In conventional nasal endoscopes, the outer diameter of the insertion portion is reduced by making the forceps channel thinner than the inner diameter of the forceps channel of the oral type endoscope (for example, φ2.8 mm → φ2.0 mm). doing. Therefore, since a general-purpose treatment tool used for an oral type endoscope cannot be used with a nasal endoscope, a dedicated treatment tool is used.

  In order to prevent the forceps channel from being damaged by a load when the bending portion bends, an endoscope in which the forceps channel 131 is disposed at substantially the center in at least the bending portion 130 as in the bending portion 130 shown in FIG. It has been invented (see Patent Document 1). In this endoscope, built-in objects 132 such as an air / water supply channel and a light guide are arranged in a space partitioned by a forceps channel 131 and a wire guide 133.

FIG. 17A shows the state of the built-in object 132 in the insertion portion 135. Since the built-in objects 132 such as the air / water supply channel and the light guide are arranged on the outer periphery of the forceps channel 131 arranged in the center, the bending direction of the bending portion 130 changes, so that the outer peripheral side or inner periphery of the curved shape is changed. Become the side. As shown in FIG. 5B, when the built-in object 132 is positioned on the outer periphery side of the curved shape, the built-in object 132 has a longer axial length in the bending portion 130 than before being bent. It is pulled toward the distal end side of the portion 135 and moves in the insertion portion 135 toward the distal end side. Further, as shown in FIG. 6C, when the built-in object 132 is positioned on the inner peripheral side of the curved shape, the built-in object 132 has a shorter axial length in the bending portion 130 than before the curve. Therefore, it is pushed to the front end side of the insertion part 135 and moves in the insertion part 135 to the rear end side.
Japanese Patent Laid-Open No. 10-033467

  When the bending part 130 is bent and the built-in object 132 moves to the rear end side of the insertion part 135, the movement of the built-in object 132 is hindered by the sliding resistance with the inner wall of the insertion part 135 or other built-in object. Sometimes. At this time, the built-in object 132 may bend in the bending portion 130 and buckle as shown by an arrow A in FIG. When the buckled built-in object 132 is a light guide, the optical fiber is broken, so that illumination light cannot be obtained. In addition, if the air / water channel buckles, air and water cannot be supplied.

  A transnasal type endoscope has been developed in which the inner diameter of the forceps channel is made as large as that of an oral type endoscope so that a general-purpose treatment instrument can be used. In this endoscope, the diameter of a built-in object other than the forceps channel, such as an air / water supply channel and a light guide, is reduced to secure a space for accommodating the forceps channel. However, if the diameter of the air / water supply channel, the light guide, etc. is reduced, the rigidity is lowered, so that there is a concern that buckling is likely to occur.

  An object of the present invention is to make it difficult for a built-in object to buckle in a curved portion.

An endoscope according to the present invention includes an insertion portion that is inserted into a body cavity, a bending portion that has a bendable structure so that the orientation of the distal end of the insertion portion can be changed, and is inserted into the insertion portion, from the distal end of the insertion portion. A forceps channel for projecting the treatment tool, and a forceps channel disposed substantially at the center in the bending portion, and a forceps channel that is inserted into the insertion portion and is disposed around the forceps channel in the bending portion, in a direction perpendicular to the longitudinal direction of the insertion portion. a built product inner wall thickness is uneven at the curved portion, the major axis, which is the thickness of the circumferential direction of the insertion portion in the curved portion, it is longer than the minor diameter which is the thickness in the radial direction of the insertion portion It has an elliptical shape and is provided with a tube-like built-in object provided with a circular inner diameter portion . In addition, the pushing force required to buckle the oval built-in object into the predetermined gap is the same as the outer diameter of the minor axis of the oval built-in object, and the inner diameter part of the oval built-in object. possess a bore of the same diameter, cross-section is 5-7 times the pushing force required to buckle is pushed into the gap the tubular internals that are circular.

When the minor axis of the oval built-in object is 0.9 mm, the major axis may be 1.7 mm or less.

  According to the present invention, the thickness of the built-in object inserted through the insertion part is made non-uniform in the direction orthogonal to the longitudinal direction of the insertion part, so that the rigidity of the built-in object can be improved. Thereby, when an insertion part curves, it can prevent that a built-in thing buckles within an insertion part. Moreover, even if the diameter of the built-in object is reduced, high rigidity can be obtained due to the uneven thickness, which can contribute to a reduction in the diameter of the insertion portion.

  Further, since the thickness of the built-in object is greater in the circumferential direction of the insertion portion than in the radial direction of the insertion portion, the bending rigidity of the insertion portion in the bending direction can be further improved. Furthermore, since the portion having a non-uniform thickness is set in the bending portion, buckling of the built-in object in the bending portion can be reduced.

  In the bending portion, the forceps channel is arranged in the center, and the built-in object is arranged around the forceps channel, so that the arrangement balance is good and the bending can be performed smoothly. In addition, the forceps channel is not subjected to an excessive load when the bending portion is bent, so that breakage can be prevented.

  An endoscope 11 illustrated in FIG. 1 is, for example, a nasal type upper endoscope, and includes an insertion portion 12 that is inserted into a body cavity from a nostril and an operation portion that is connected to a proximal end portion of the insertion portion 12. 13 and a universal cord 14 provided in the operation unit 13. The operation unit 13 is provided with a forceps insertion port 15 through which a treatment tool is inserted. The forceps insertion port 15 is connected to a forceps channel 16 disposed in the insertion portion 12 as indicated by a broken line.

  The insertion portion 12 is an elongated hollow rod-like body having a diameter of about 6 mm and a length of about 1 to 2 m. The insertion portion 12 includes a hard portion 19, a bending portion 20, and a soft portion 21 from the distal end side.

  As shown in FIG. 2, the distal end surface of the rigid portion 19 is circular, and an imaging window 24 used for imaging inside the body cavity is provided at the center upper part. Illumination windows 25 for illuminating the inside of the body cavity are arranged on both sides of the imaging window 24. The photographing window 24 and the illumination window 25 are closed with a transparent protective plate. An air / water supply nozzle 26 that blows and cleans the shooting window 24 by blowing air or water is disposed on the lower left side of the shooting window 24. A forceps outlet 27 connected to the forceps channel 16 is provided on the lower right side of the distal end surface. Note that U, D, L, and R written around the rigid portion 19 represent the upper, lower, left, and right directions of the bending portion 20, respectively.

  The rigid portion 19 incorporates a photographing lens and an image sensor (not shown). The imaging element captures image light in the body cavity imaged by the imaging lens through the imaging window 24. An image pickup signal obtained by the image pickup device is sent to a processor device (not shown) connected to the universal cord 14 via a signal line 30 (see FIG. 5) inserted through the insertion unit 12 and the operation unit 13, and is sent to a monitor. Displayed as an endoscopic image.

  As shown in FIG. 3, the bending portion 20 is configured to be freely bent by a plurality of (for example, 16) bending pieces 33 connected in series. The outer periphery of the bending piece 33 is covered with a flexible outer skin 34. Although not shown in detail, the leading and trailing bending pieces 33 are fixed to the hard part 19 and the soft part 21.

  As shown in FIG. 4, the bending piece 33 is provided so as to protrude from the cylindrical portion 37, the end portion on the distal end side of the cylindrical portion 37, and a pair of inner tongues 38 facing each other, and an end on the proximal end side It consists of a pair of outer tongues 39 which are provided so as to protrude from the part and face each other.

  The inner tongue 38 is formed in a substantially disc shape and has a connecting hole 42 at the center thereof. The outer tongue 39 is formed in a substantially disk shape that is slightly smaller than the inner tongue 38, and has a connection hole 43 that is slightly smaller than the connection hole 42 of the inner tongue 38. The inner tongue 38 and the outer tongue 39 are alternately arranged at intervals of 90 ° in the circumferential direction of the cylindrical portion 37. The inner tongue 38 is located at a position substantially shifted from the outer tongue 39 in the radial direction of the cylindrical portion 37 by the thickness of the plate.

  The bending pieces 33 are connected to each other via a connecting pin 46. The connecting pin 46 includes a small-diameter portion 47, a large-diameter portion 48, a contact portion 49, and a wire guide portion 50, which are each formed in a cylindrical shape. The connecting pins 46 are configured such that the circumferential postures of the adjacent bending pieces 33 are shifted by 90 ° from each other so that the outer tongue 39 of the bending piece 33 on the distal end side overlaps with the inner tongue 38 of the bending piece 33 on the proximal end side. Above, the small diameter portion 47 is inserted into the connection hole 43 and the large diameter portion 48 is inserted into the connection hole 42, and the end face of the large diameter portion 48 is applied to the inner surface of the outer tongue 39 to rotate the bending pieces 33. Connect freely. After the bending pieces 33 are connected to each other, the distal end of the small diameter portion 47 is crimped, and the connection pin 46 is prevented from falling off the bending piece 33. Further, the thickness in the axial direction of the large-diameter portion 48 is larger than the plate thickness of the inner tongue 38, so that the inner tongue 38 and the outer tongue 39, the inner tongue 38 and the contact portion 49, A gap is created between the two, and the proximal-side bending piece 33 can be smoothly rotated.

  A guide hole 53 is formed in the wire guide portion 50 so as to penetrate in the radial direction. Up and down or left and right operation wires 54 and 55 are inserted into the guide hole 53. Each of the operation wires 54 and 55 is fixed to the rigid portion 19 at one end, passes through the bending portion 20 and the flexible portion 21, and rotates with the up and down or left and right angle knobs 56 and 57 (see FIG. 1) in the operation portion 13. The other end is also fixed to the rigid portion 19 by being folded over (not shown).

  The vertical operation wire 54 is pushed and pulled within the insertion portion 12 when the vertical angle knob 56 is operated. Similarly, when the left / right angle knob 57 is operated, the left / right operation wire 55 is pushed and pulled in the insertion portion 12. Each bending piece 33 of the bending portion 20 rotates around the connecting portion in conjunction with the movement of the operation wires 54 and 55. Thereby, the direction of the hard part 19 can be freely changed.

  As shown in FIG. 5, the flexible portion 21 has a configuration in which a screw tube 60 obtained by spirally winding a band-shaped metal is covered with a resin outer shell 34 and has flexibility. An air / water supply channel 62 and two light guides 63 are inserted into the insertion portion 12 including the flexible portion 21 together with the forceps channel 16, the signal line 30, and the operation wires 54 and 55 described above.

  The forceps channel 16 is a tube formed of a waterproof and flexible plastic, silicon or the like, and has a circular cross section. The forceps channel 16 has, for example, an inner diameter portion 16a having a diameter of 2.8 mm. The inner diameter portion 16a is larger than the inner diameter φ2.0 mm of the forceps channel used in a conventional nasal endoscope, and is similar to an oral type endoscope. Can be made. The forceps channel 16 is disposed on the lower left side in the flexible portion 21.

  The signal line 30 includes a plurality of electric wires 66 and an outer skin 67 that covers these electric wires. The outer skin 67 is formed of a waterproof and flexible plastic, silicon or the like. The signal line 30 is disposed above the forceps channel 16 in the flexible portion 21.

  The air / water supply channel 62 is a tube formed of plastic, silicon or the like having waterproofness and flexibility. The inner diameter portion 62a has a circular cross section in consideration of reduction of the flow resistance of air and water. The air / water supply channel 62 is inserted from the air / water supply nozzle 26 to the universal cord 14 through the operation unit 13, and is connected to an air / water supply pump (not shown) via the universal cord 14. The air / water supply channel 62 supplies the air / water supplied from the air / water supply pump to the air / water supply nozzle 26. The air / water supply nozzle 26 is disposed in the flexible portion 21 at the upper right of the forceps channel 16 and the lower right of the signal line 30.

  The light guide 63 constitutes a part of a light source device that illuminates the inside of the body cavity, and covers the optical fiber 70 having an outer diameter of about 0.1 to 0.2 mm and a circular cross-sectional shape. A skin 71 is provided. The outer skin 71 is formed of a waterproof and flexible plastic, silicon or the like. In the present embodiment, a laser white light source using blue semiconductor laser light and a phosphor material, for example, “Micro White (trade name: Nichia Corporation)” is used as the light source device.

  The rear end of the optical fiber 70 is inserted through the operation unit 13 to the universal cord 14 and connected to a light source device (not shown) via the universal cord 14. A phosphor (not shown) that is excited by blue semiconductor laser light and emits white light is attached to the tip of the optical fiber 70. The phosphor faces the illumination window 25 in the hard part 19. The light guide 63 is disposed in a gap between the flexible portion 21 and the forceps channel 16 so as to sandwich the forceps channel 16.

  The light source device makes blue semiconductor laser light enter from the rear end of the optical fiber 70. The blue semiconductor laser light guided to the tip side of the optical fiber 70 excites the phosphor to emit white light. The white light illuminates the body cavity through the illumination window 25. Micro white can obtain the same amount of light as the optical fiber of φ1.2 mm by the optical fiber of φ0.16 mm. Therefore, by using micro white for the endoscope 11, the diameter of the endoscope 11 can be reduced while maintaining a necessary amount of illumination light.

  The operation wires 54 and 55 are disposed in the flexible portion 21 between the signal line 30 and the light guide 63 and between the air / water supply channel 62 and the light guide 63.

  As shown in FIG. 6, the position of the forceps channel 16 in the bending portion 20 is regulated by the connecting pin 46 and is arranged at the center of the bending portion 20. Further, around the forceps channel 16, first to fourth spaces 74 to 77 separated by the connecting pin 46 are formed. Built-in objects such as the light guide 63, the signal line 30, the light guide 63, and the air / water supply channel 62 are inserted into the first to fourth spaces 74 to 77, respectively.

  The cross-sectional shapes of the light guide 63 and the outer skins 67 and 71 of the signal line 30 and the air / water supply channel 62 have a major axis and a minor axis in the circumferential direction of the curved portion 20 according to the shapes of the first to fourth spaces 74 to 77. And an elliptical shape along the radial direction. As shown in FIG. 7, the outer skins 67 and 71 and the air / water supply channel 62 have a circular cross section in the hard part 19 and the soft part 21, and have an elliptical shape only in the curved part 20. In FIG. 7, the illustration of the forceps channel 16, the connecting pin 46, the operation wires 54 and 55, and the like are omitted in order to illustrate the shapes of the air / water supply channel 62 and the light guide 63 in the insertion portion 12.

  The cross-sectional shapes of the outer skins 67 and 71 and the air / water supply channel 62 are preferably gradually changed so that they are less likely to be caught when moving in the axial direction within the insertion portion 12. In addition, as shown in FIG. 17B, the built-in object on the outer peripheral side of the curved bending portion 20 is drawn into the bending portion 20. Therefore, even if the outer skins 67 and 71 and the air / water supply channel 62 are portions accommodated in the flexible portion 21 when the bending portion 20 is in a straight state, the outer skins 67 and 71 and the air / water supply channel 62 are elliptical to a portion that is drawn into the bending portion 20 during bending. The shape is preferred.

  Further, the outer skins 67 and 71 and the air / water supply channel 62 have a non-uniform thickness by making the cross-sectional shape of the optical fiber 70 and the inner diameter portion 62b circular and making the housing space of the electric wire 66 different from the outer skin 67. It has become. In addition, the thickness distribution of the outer skins 67 and 71 and the air / water supply channel 62 is such that the circumferential direction of the curved portion 20 is thicker than the radial direction. In this embodiment, the thickness ratio in the circumferential direction to the thickness in the radial direction is about three times, for example, but can be set as appropriate according to the material, diameter, etc. of the built-in object.

  As shown in FIG. 7, in the air / water supply channel 62, the inner diameter portion 62 a in the hard portion 19 and the soft portion 21 has a larger diameter than the inner diameter portion 62 b in the bending portion 20. Thereby, even if the diameter of the inner diameter portion 62b is defined in accordance with the space in the bending portion 20, the occurrence of pressure loss can be prevented. The cross-sectional area ratio of the inner diameter portion 62a to the inner diameter portion 62b is preferably about 1.1 to 3 times, for example.

  As shown in FIG. 8, a tension mechanism 80 that pulls the light guide 63 toward the operation unit 13 is provided in the operation unit 13. The tension mechanism 80 includes a pair of guide rollers 81 and 82 on which the light guide 63 is hung, and a tension roller 83 movable between the guide rollers 81 and 82 in a direction perpendicular to the axial direction of the light guide 63. And a spring 84 that urges the tension roller 83 in a direction in which the light guide 63 is tensioned.

  The operation of the above embodiment will be described. As shown in FIG. 1, the insertion part 12 of the endoscope 11 is inserted from a patient's nostril. When the vertical angle knob 56 and the horizontal angle knob 57 are operated, the operation wires 54 and 55 are pushed and pulled in the insertion portion 12. Each bending piece 33 rotates around the connecting portion in conjunction with the movement of the operation wires 54 and 55, the bending portion 20 is bent, and the direction of the rigid portion 19 is freely changed.

  Since the bending portion 20 has a good arrangement balance of the built-in objects, the bending portion 20 can be bent smoothly. Further, since the forceps channel 16 is arranged at the center, an excessive load is not applied when the bending portion 20 is bent. Thereby, damage to the forceps channel 16 can be prevented. Further, since the built-in objects such as the forceps channel 16 are accommodated at a high density so as not to generate a large gap in the bending portion 20, the respective built-in objects maintain the alignment in the bending portion 20. As a result, each built-in object does not move in the radial direction within the bending portion 20, and therefore, it is possible to prevent the built-in object from being violently damaged within the bending portion 20.

  As shown in FIG. 6, built-in objects such as the air / water supply channel 62 and the light guide 63 in the bending portion 20 are arranged on the outer periphery of the forceps channel 16 arranged in the center. As shown in FIG. 17C, when the bending portion 20 is bent, the built-in object positioned on the inner peripheral side of the curved shape is pushed by the rigid portion 19 and moves in the insertion portion 12 to the rear end side. . During the movement of the built-in object, the movement of the built-in object may be hindered by sliding resistance with the inner wall of the insertion portion 12 or other built-in object.

  Built-in objects such as the light guide 63, the signal line 30, and the air / water supply channel 62 in the bending portion 20 have an oval shape whose outer diameter matches the first to fourth spaces 74 to 77 around the forceps channel 16. Therefore, the movable amount of each built-in object in the bending portion 20 in the circumferential direction is small. Thereby, even if it is a case where the movement to the rear end side of a built-in thing is inhibited, since there is no space for a built-in thing to bend in the bending part 20, it becomes difficult for a built-in thing to buckle.

  Further, the outer skins 67 and 71 and the air / water supply channel 62 are non-uniform so that the circumferential thickness of the curved portion 20 is greater than the radial thickness. Thereby, since each built-in thing has improved rigidity, it is difficult to buckle when the bending portion 20 is bent.

  Further, since the light guide 63 is always pulled toward the rear end side by the tension mechanism 80 shown in FIG. 8, it is possible to prevent the light guide 63 from being bent and buckled in the bending portion 20.

In order to examine the relationship between the cross-sectional shape of the built-in object and buckling, CAE (Computer Aided Engineering) analysis was performed. As shown in FIG. 9, the cross-sectional shape of the built-in object 85 used for the study was an elliptical shape in consideration of the empty space in the bending portion 20. The following conditions were used as conditions for studying the dimensions and materials of the built-in object 85, the minimum bending radius of the bending portion, and the like.
Examination conditions Inner diameter D: 0.6 mm
Long diameter L1: 1.7 mm or less Short diameter L2: 0.9 mm
Material: Polytetrafluoroethylene (PTFE)
Minimum bending radius of the curved part: about 6mm

  Based on the hypothesis that the buckling of the built-in object is a bending buckling generated by bending the built-in object together with the bending portion, the relationship between the bending radius of the built-in object 85 and the occurrence of buckling was examined. In actual examination, a CAE model 87 shown in FIG. 10 is created on a computer based on the cross-sectional shape of the built-in object 85, and this is converted into a bending direction A that is the major axis direction and a bending direction B that is the minor axis direction. The radius (buckling radius) at which buckling occurs when bending was determined. As the buckling radius, the bending radius when the torque generated as a reaction force when the CAE model 87 is bent reaches its peak.

  The graph of FIG. 11 shows the buckling radius when the major axis L1 of the CAE model 87 is 0.9 to 1.7 mm. Although the buckling radius of the built-in object 85 is weaker in the bending direction A than in the bending direction B, both the bending directions A and B are significantly less than the minimum bending radius 6 mm of the bending portion. From this result, the buckling occurring in the built-in object 85 is not the bending buckling due to the bending of the bending part, but the built-in object 85 moves in the insertion part when the bending part is bent, and the sliding at that time It is considered that the built-in object 85 bends due to the resistance and buckling occurs, which is a push-in buckling.

  Further, it can be seen from the graph that the built-in object 85 is most resistant to buckling when the major axis L1 is 1.3 to 1.4 mm and the minor axis L2 is 1.7 mm. However, in order to prevent indentation buckling, it is considered that it is effective to reduce the gap of the accommodation space of the built-in object 85 in the bending portion, and the buckling radius due to the change of the major axis L1 in the bending direction A. Since the change in is small compared to the bending radius of the bending portion, it is considered that the major axis L1 is about 1.7 mm.

  Next, CAE analysis was performed on the indentation buckling of the built-in object 85. In this analysis, the amount of gap around the built-in object 85 is changed, and when the built-in object 85 is pushed in, the pushing force reaching the above-described buckling radius is obtained. In actual examination, as shown in FIG. 12, a pair of rigid elements 89 arranged so as to form a gap S, and the rigid elements 89 are inserted so as to be curved and come into contact with the rigid elements 89. The beam element 90 is used, one end 90a of the beam element 90 is fixed, the other end 90b is pushed between the rigid elements 89 by the pushing force W, and the pushing force when the bending radius R of the beam element 90 reaches the buckling radius Seeking W. The beam element 90 has a circular cross section with an outer diameter of 0.9 mm and an inner diameter of 0.6 mm, in which the cross-sectional shape is buckled in the built-in object 85 (sample A) shown in FIG. 9 and an actual endoscope. (Sample B) was used.

  The table of FIG. 13 shows the pushing force W that the beam element 90 bends to the buckling radius and the bending rigidity when the gap S is 1 mm and 2 mm. As can be seen from this table, by changing the cross-sectional shape of the built-in object from a circle with an outer diameter of 0.9 mm to an elliptical shape with a major axis of 1.7 mm, the thickness becomes uneven and the bending rigidity is improved. The pushing force W required for buckling, that is, the buckling resistance, is increased 5 to 7 times. Therefore, if the main factor of buckling of the built-in object is indentation buckling, it can be improved by using the built-in object having a non-uniform cross-sectional thickness. Further, since the bending rigidity of the built-in object is sufficiently small compared to the bending rigidity of the entire bending portion 20, the operability of the endoscope 11 is not impaired even if the bending rigidity of the built-in object is improved.

  In the above-described embodiment, the cross-sectional shape of the built-in object is an ellipse, but the present invention is not limited to this, and it is sufficient that the thickness is not uniform so as to improve the rigidity of the built-in object. For example, it may be fan-shaped like a built-in object 93 shown in FIG. 14A, or may be rectangular like a built-in object 94 shown in FIG. In addition, the inner diameter portion of the air / water supply channel is preferably circular in cross section in consideration of the flow resistance of air and water. However, when the cross sectional area is increased in consideration of pressure loss, FIG. As shown in the air / water supply channel 95, the inner diameter portion 95a may have a shape other than a circle such as an ellipse.

  In addition, since the optical fiber used for the white laser light source is very thin, about 0.1 mm, it can be considered that the optical fiber is covered with a sheath common to the signal line. When such a configuration is used, the main built-in objects in the insertion portion are only the forceps channel, the signal line, and the air / water supply channel. For example, as shown in the bending portion 98 in FIG. The entire curved portion 98 may be filled with the cross-sectional shape of the built-in objects 99 to 101. Even a built-in object having such a cross-sectional shape has a non-uniform wall thickness and improved rigidity, so that buckling can be prevented.

  In the above embodiment, the tension mechanism is provided only in the light guide, but it may be provided in the air / water supply channel. Further, although the inner diameter of the air / water supply channel 62 is made thin in the curved portion 20, for example, the passage area may be expanded by using two air / water channels 62 in the curved portion 20. In the case of an elliptical tube, it is possible to provide two inner diameter portions. Furthermore, although the example using a white laser light source was demonstrated, this invention is applicable also to the endoscope which used the conventional halogen lamp and the optical fiber.

  Although the endoscope according to the present invention has been described in detail above, the present invention is not limited to the above-described embodiments, and various improvements and modifications may be made without departing from the gist of the present invention. Of course. Further, the present invention can be used not only for a nasal type upper endoscope but also for an oral type endoscope and a lower endoscope.

It is a top view which shows the external appearance of an endoscope. It is a front view which shows the front end surface of a hard part. It is sectional drawing of the axial direction of a curved part. It is a perspective view which shows the structure of a bending piece. It is sectional drawing of the radial direction of a soft part. It is sectional drawing of the radial direction of a curved part. It is an axial sectional view showing the shape of the built-in object in the bending portion. It is the schematic which shows the tension mechanism of a light guide. It is sectional drawing showing the shape of the built-in object used for the CAE analysis. It is a perspective view which shows the external appearance shape of the built-in thing used for the CAE analysis. It is a graph which shows the relationship between the major axis of a built-in thing, and a buckling radius. It is explanatory drawing which shows the model used for the CAE analysis of indentation buckling. It is a table | surface which shows the analysis result of indentation buckling. It is sectional drawing which shows the built-in thing of another embodiment. It is radial direction sectional drawing which shows the curved part of another embodiment. It is radial direction sectional drawing of the conventional curved part. It is explanatory drawing which shows the movement amount and moving direction of a built-in thing by the curve of a bending part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Endoscope 12 Insertion part 16 Forceps channel 20 Bending part 30 Signal line 33 Bending piece 46 Connection pin 50 Wire guide part 62 Air supply / water supply channel 63 Light guide 67,71 Outer skin 85 Built-in 87 CAE model

Claims (2)

An insertion part to be inserted into the body cavity;
A bending portion having a bendable structure so that the direction of the tip of the insertion portion can be changed;
A forceps channel that is inserted into the insertion portion and causes a treatment tool to protrude from a distal end of the insertion portion; and the forceps channel that is disposed substantially in the center in the bending portion;
Wherein is inserted through the insertion portion is disposed around the forceps channel in the curved portion, a storehouse was among the thickness in the direction orthogonal to the longitudinal direction of the insertion portion is nonuniform said curved portion, said A tube having an elliptical shape in which a major axis that is a thickness in the circumferential direction of the insertion portion in the bending portion is longer than a minor axis that is a thickness in the radial direction of the insertion portion, and a circular inner diameter portion is provided. Said built-in shape ,
In an endoscope comprising:
The pushing force required to buckle the elliptical built-in object into a predetermined gap is the same as the outer diameter of the minor axis of the elliptical built-in object and the elliptical built-in object. have a inner diameter portion of the same diameter as the inner diameter portion, and wherein the cross-section is 5-7 times of the pushing force required to buckle push the tubular internals which is circular in the gap Endoscope. The endoscope according to claim 1 , wherein when the minor axis of the elliptical built-in object is 0.9 mm, the major axis is set to 1.7 mm or less .

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