US20120184818A1 - Endoscope - Google Patents

Abstract

There is provided an endoscope that prevents occurrence of buckling of a flexible body built in an insertion part of the endoscope without damaging other built-in components, and is easy to manufacture without impairing the curving manipulability. The endoscope includes a curvable portion, and an elongated insertion part being inserted into a subject. The endoscope has an elongated flexible body built in the insertion part, and a flexible protective tube that covers an outer periphery of the flexible body. The protective tube has a first region that covers the range of the flexible body, and a second region that covers the range of the soft portion. The elastic constant of the first region is smaller than the elastic constant of the second region, and the external diameter of the protective tube in the first region is larger than the external diameter of the protective tube of the second region.

Description

BACKGROUND OF THE INVENTION
• 1. Field of the present invention
• The present invention relates to an endoscope including a curvable portion.
• 2. Description of the Related Art
• Endoscopes widely used for medical and industrial uses have an insertion part to be inserted into a subject (into a body cavity), and a manipulating part that is manipulated by an operator, and built-in components, such as optical fibers for illumination, forceps channel through which a treatment tool is inserted, an air supply and water supply channel, are arranged in the insertion part. Moreover, a curvable portion that is operated to curve is provided at the distal end of the insertion part, and the curvable portion can be curved up and down and right and left in conjunction with angle knobs of the manipulating part (for example, refer to JP 2007-37649A).
• These built-in components, such as optical fibers, are flexible bodies that are apt to curve. JP 2007-37649A describes a configuration in which a flexible body to be bent is protected by densely and spirally winding an element wire having predetermined elasticity around an outer periphery of a flexible body that is a built-in component to form a regulating part in which adjacent element wires are bonded and fixed to each other. In this endoscope, the regulating part is arranged particularly in the region of the curvable portion that is apt to bend in the flexible body to prevent occurrence of buckling or decrease in lifespan.
SUMMARY OF THE INVENTION
• However, in the configuration in which the element wire is densely and spirally wound on the outer periphery of the flexible body, the manufacturing process becomes complicated and the costs become high. Additionally, since a level difference caused by the element wires occurs outside the flexible body, and the surface of the element wire is hard, other built-in components are apt to be damaged. Moreover, when the element wire that is densely and spirally wound is unwound from the outer periphery of the flexible body, there is a concern that other built-in components may be damaged or the element wire may catch. Additionally, since the diameter of the flexible body is increased due to the spiral element wire, this configuration is disadvantageous to reducing the diameter of the insertion part. Moreover, in the case of an endoscope of a type in which a blue laser beam from a laser light source and green to yellow excitation light components obtained by wavelength conversion with fluorescent bodies are synthesized to generate white light, a single mode fiber (for example, optical fiber) with a diameter which is reduced to about 0.3 mm is used the flexible body. If the flexible body with the reduced diameter is used, the durability of the flexible body is not sufficiently secured due to the reduction in diameter, and the flexible body is apt to be damaged due to buckling or bending of the flexible body when the endoscope is manufactured and when the endoscope is used.
• The present invention has been made in view of the above-mentioned problems and an object of the present invention is to provide an endoscope that prevents a flexible body with a reduced diameter, such as an optical fiber, which is built in an insertion part of the endoscope, from being damaged due to buckling, bending, or the like, without damaging other built-in components, and is easy to manufacture without impairing the curving manipulability of a curvable portion.
• The present invention has the following configuration. An endoscope including a curvable portion provided to extend at a distal end of a soft portion having flexibility, an elongated insertion part to be inserted into a subject, an elongated flexible body built in the insertion part, and a flexible protective tube that covers an outer periphery of the flexible body, the protective tube having a first region that covers the flexible body located at least in the curvable portion, and a second region that covers the flexible body located in the soft portion, and the elastic constant of the first region being smaller than the elastic constant of the second region, and the external diameter of the protective tube in the first region being larger than the external diameter of the protective tube of the second region.
• In the endoscope of the present invention, the flexible body that is built in the insertion part of the endoscope and is covered with the protective tube in which the elastic constant of the protective tube located at least in the curvable portion is smaller than the elastic constant of the protective tube located in the soft portion, and the external diameter of the protective tube in the first region is larger than the external diameter of the protective tube of the second region, so that this flexible body does not undergo any damage, and the buckling of the flexible body can be prevented without damaging other built-in components. Moreover, since the elastic constant of the protective tube of the curvable portion is small, the required torque for the curving manipulation of the curvable portion is suppressed to be small. Since the flexible body covered with the protective tube can be smoothly put into the insertion part during manufacture, the assemblability when the endoscope is manufactured improves.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a view illustrating an embodiment of the present invention, and a configuration diagram of an endoscope apparatus showing an endoscope and respective devices to which the endoscope is connected.
• FIG. 2 is an external view showing a specific configuration example of the endoscope apparatus.
• FIG. 3 is a graph showing spectral characteristics of emission light.
• FIG. 4 is a perspective view of an endoscope distal end portion.
• FIG. 5 is a schematic cross-sectional configuration diagram in a cross-section A-A ofFIG. 4.
• FIG. 6 is a schematic cross-sectional configuration diagram in a cross-section B-B ofFIG. 4.
• FIG. 7 is a configuration diagram of a light guide unit.
• FIG. 8 is an explanatory view showing the arrangement relationship between the endoscope insertion part and the light guide unit.
• FIG. 9A is a schematic explanatory view showing a configuration in which a connection part between a first protective tube and a second protective tube is provided at a soft portion when a plurality of light guide units is built in the endoscope insertion part, andFIG. 9B is a schematic explanatory view showing a configuration in which the connection part is provided at an axially different position that is different for each light guide.
• FIG. 10 is a schematic explanatory view showing a case where bending has occurred in a portion of the light guide unit when a curvable portion is curved.
• FIG. 11 is a cross-sectional view of the first protective tube.
• FIG. 12 is an explanatory view showing a state where the first protective tube is bent at 180°.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
• An embodiment of the present invention will be described in detail with reference to the accompanying drawings.
• FIG. 1 is a view illustrating the embodiment of the present invention, and a configuration diagram of an endoscope apparatus showing an endoscope and respective devices to which the endoscope is connected, andFIG. 2 is an external view showing a specific configuration example of the endoscope apparatus.
• Theendoscope apparatus100, as shown inFIG. 1, includes anendoscope11, acontrol device13, adisplay unit15, such as a monitor, and aninput unit17, such as a keyboard or a mouse through which information is input to thecontrol device13. Thecontrol device13 has alight source device19 and aprocessor21 that performs signal processing of a captured image.
• Theendoscope11 includes abody manipulating part23 and anelongated insertion part25 connected to thebody manipulating part23 and inserted into a subject (body cavity). Auniversal cord27 is connected to thebody manipulating part23, and a distal end of theuniversal cord27 is connected with thelight source device19 via a light guide (LG)connector29A, and is connected to theprocessor21 via avideo connector29B.
• As shown inFIG. 2, in thebody manipulating part23 of theendoscope11,various manipulation buttons31, such as buttons for carrying out suction, air supply, and water supply at the distal end of theinsertion part25, and a shutter button during imaging, are installed together, and a pair ofangle knobs33 is provided.
• Theinsertion part25 is constituted by asoft portion35, acurvable portion37, and a distal end portion (endoscope distal end portion)39 sequentially from thebody manipulating part23 arranged at a proximal end. Thecurvable portion37 is remotely curved by turning theangle knobs33 of thebody manipulating part23, so that thedistal end portion39 is directed to a desired direction.
• As shown inFIG. 1, anobservation window41 of an imaging optical system andillumination windows43A and43B of an illumination optical system are arranged at the endoscopedistal end portion39. Reflected light from a subject caused by illumination light radiated from therespective illumination windows43A and43B is imaged by animaging device45 through theobservation window41. The imaged observation image is displayed on thedisplay unit15 connected to theprocessor21.
• The imaging optical system has theimaging device45, such as a CCD (Charge Coupled Device) type image sensor or a CMOS (Complementary Metal Oxide Semiconductor) type image sensor, and anoptical member47, such as a lens that forms an observation image on theimaging device45. The observation image that is formed on a light-receiving plane of theimaging device45 and is fetched, is converted into electrical signals, and the converted image signals are input to an imagingsignal processing unit53 of theprocessor21 through asignal cable51, and are converted into video signals in the imagingsignal processing unit53.
• Theprocessor21 includes acontrol unit63, and an imagingsignal processing unit53 that generates video signals. Thecontrol unit63 performs proper image processing on image data of the observation image output from the imagingsignal processing unit53, and makes the image-processed image data projected on thedisplay unit15. Additionally, a driving signal is output to a laser light source LD of thelight source device19 so as to make illumination light with a desired light quantity be emitted from therespective illumination windows43A and43B. Thecontrol unit63 is connected to networks, such as a LAN (not shown), to control theoverall endoscope apparatus100, such as distributing information including image data.
• The illumination optical system has thelight source device19, a pair ofoptical fibers55A and55B connected to thelight source device19 via theconnector29A, andwavelength converting members57A and57B respectively arranged at light emission ends of theoptical fibers55A and55B. Thelight source device19 has a laser light source LD that is a semiconductor light-emitting element, and theoptical coupler61 that branches the emission light from laser light source LD, and introduces the branched emission light into the respectiveoptical fibers55A and55B.
• The laser light source LD is a semiconductor laser that emits blue light with a central wavelength of 445 nm, for example, a broad area type InGaN-based laser diode can be used. Additionally, the laser light source LD may be constituted by a plurality of laser light sources, for example, may be combined with a semiconductor laser that emits purple light with a central wavelength of 405 nm so as to make light be selectively output from each laser light source.
• Thewavelength converting members57A and57B include a plurality of kinds of fluorescent bodies (for example, fluorescent bodies or the like including a YAG-based fluorescent body or BAM (BaMgAl₁₀O₃₇)), which absorb a portion of a blue laser beam output from the laser light source LD and are excited in green to yellow to emit light. The blue laser beam from the laser light source LD and the green excitation to yellow excitation light that are obtained by converting the wavelength of this blue laser beam are synthesized to generate white light by thewavelength converting members57A and57B so as to show spectral characteristics of emission light inFIG. 3.
• Thecontrol unit63 of theprocessor21 controls the light quantity of the laser light source LD to make a laser beam output from the laser light source LD. The output laser beam is introduced into the respectiveoptical fibers55A and55B, and is guided to the endoscopedistal end portion39. The laser beam guided to theoptical fibers55A and55B is irradiated to thewavelength converting members57A and57B, and thereby, white illumination light is emitted from theillumination windows43A and43B.
• FIG. 4 is an external perspective view of the endoscopedistal end portion39,FIG. 5 is a schematic cross-sectional configuration diagram in a cross-section A-A ofFIG. 4, andFIG. 6 is a schematic cross-sectional configuration diagram in a cross-section B-B ofFIG. 4.
• As shown inFIG. 4, the above-mentionedobservation window41 for observing a subject, and theillumination windows43A and43B that emit illumination light are arranged at the endoscopedistal end portion39, and theillumination windows43A and43B are arranged on both sides of theobservation window41. Additionally, aforceps opening65 through which various kinds of forceps are inserted, an air supply andwater supply nozzle67 that supplies air and supplies water toward theobservation window41 are arranged at the endoscopedistal end portion39.
• As shown in a cross-sectional configuration ofFIG. 5, a distal endhard portion71 made of a metallic material, such as a stainless steel material, animaging unit75 fixed by fitting alens barrel73 into abored hole71aformed in the distal endhard portion71, aforceps pipe77 disposed in a differentbored hole71b, aforceps tube79 made of a soft material connected to themetal forceps pipe77, alight guide unit81 of the illumination optical system, and the like are arranged at the endoscopedistal end portion39.
• Theimaging unit75 includes thelens barrel73 in which anobjective lens83 that becomes theobservation window41 is accommodated, aprism85 that changes the direction of light fetched from thelens barrel73 at right angles, and theimaging device45 that forms the light fetched via theprism85 mounted on acircuit board87 as an image to generate image signals. As mentioned above, the image information output from theimaging device45 is transmitted to the imagingsignal processing unit53 of the processor21 (refer toFIG. 1) via thesignal cable51, and is processed into an image for display.
• The abovelight guide unit81 and thesignal cable51, as shown inFIG. 6, are built in along the axial direction of theendoscope insertion part25 along with to theforceps tube79 or the air supply andwater supply tube89 connected to the air supply and water supply nozzle67 (refer toFIGS. 4 and 5).
• Here, thelight guide unit81 in which theillumination windows43A and43B of the illumination optical system, thewavelength converting members57A and57B, and theoptical fibers55A and55B are integrally formed will be described.
• As shown inFIG. 7, thelight guide unit81 has a distal end light-projectingportion91, an optical fiber55 (55A,55B) that is a flexible body of which a light emission end is connected to the distal end light-projectingportion91, and aprotective tube93 that covers the outer periphery of theoptical fiber55.
• The distal end light-projectingportion91 has a cylindricaldistal end sleeve97 one face of which is blocked by a light-projectingplate95 that becomes an illumination window43 (43A,43B), a wavelength converting member57 (57A,57B) that is arranged in thedistal end sleeve97, acoupling member99 that couples the distal end side of theprotective tube93 and the proximal end side of thedistal end sleeve97 together, and aferrule101 that is arranged inside thecoupling member99 to support theoptical fiber55.
• Theprotective tube93 has a firstprotective tube93A, a secondprotective tube93B, and a connectingmember103 that has acentral hole103abored therein and coaxially connects the firstprotective tube93A and secondprotective tube93B together. Theoptical fiber55 is inserted into the internal space of each of theprotective tubes93A and93B.
• Here, Not bending the optical fiber to the bending limit radius (0.85 mm) or less of theoptical fiber55 is needed so as for theoptical fiber55 extending in thecurvable portion37 not to cause disconnection due to buckling by virtue of curving of thecurvable portion37. That is, in the firstprotective tube93A of the present configuration, a thickness t that can be found as ½ of the difference between the external diameter D and the internal diameter d is made larger than the greatest curvature radius r_maxat which theoptical fiber55 breaks due to bending as shown in the cross-sectional view of the firstprotective tube93A inFIG. 11. Thereby, even when theprotective tube93A is bent at 180° as shown inFIG. 12, and is bent with a minimum curvature radius, the curvature radius r of theoptical fiber55 becomes always larger than the curvature radius r_maxat which breaking occurs. According to this configuration, disconnection caused by buckling does not occur in theoptical fiber55 by any manipulations of thecurvable portion37. On the other hand, since the secondprotective tube93B has no necessity for carrying out curving like the curvable portion, the external diameter of the secondprotective tube93B may be smaller than the external diameter D of the firstprotective tube93A. In the present example, r_max=0.5 to 1.0 mm, t=0.6 to 1.5 mm, and the external diameter of the secondprotective tube93B is 0.8 to 2.0 mm. As such, the external diameter of the firstprotective tube93A is larger than that of the secondprotective tube93B, and the external diameter from the distal end light-projectingportion91 to the secondprotective tube93B is adapted to become smaller in a stepwise fashion. Thereby, disconnection of the optical fiber can be prevented, the handlability in a single body of thelight guide unit81 becomes good, and assembling operation into theendoscope insertion part25 becomes easy. Additionally, since the overallprotective tube93 can be formed so as to have a small diameter, reduction in the diameter of theendoscope insertion part25 is not hindered.
• Since the curvature radius of thecurvable portion37 is smaller than the curvature radius of the soft portion, the firstprotective tube93A corresponding to thecurvable portion37 requires flexibility, and it is preferable that the elastic constant of the firstprotective tube93A be smaller. On the other hand, since the length of the secondprotective tube93B corresponding to thesoft portion35 is about 10 times larger than the length of the firstprotective tube93A, if the elastic constant of the secondprotective tube93B is made equal to the elastic constant of the firstprotective tube93A, the elastic constants of the secondprotective tube93B is insufficient, and the secondprotective tube93B is apt to deflect excessively. Therefore, slidability to other members is not sufficiently secured, and the operation of assembling the secondprotective tube93B into theendoscope insertion part25 becomes difficult. For this reason, by making the elastic constant of the secondprotective tube93B larger than the elastic constant of the firstprotective tube93A, theoptical fiber55 can be maintained in a straight shape by the difficulty (elastic restoring force) of bending of the firstprotective tube93A, and the assemblability of inserting theoptical fiber55 into theendoscope insertion part25 improves. By making the elastic modulus of the firstprotective tube93A smaller than the elastic modulus of the secondprotective tube93B in this way, assemblability into theendoscope insertion part25 can be secured while having curvability in thecurvable portion37.
• The firstprotective tube93A is made of a highly flexible rubber-based material, such as silicone rubber or fluorine-based rubber. The rubber-based material is chemically stable, does not deteriorate even in the case of contact with cleaning chemicals during endoscope washing, and also has little degradation with time. One end portion of the firstprotective tube93A is inserted into a small-diameter connection part99aof thecoupling member99 on the side of the distal end light-projectingportion91, and the other end portion thereof is inserted into a small-diameter connection part103bof the connectingmember103. In addition, the firstprotective tube93A may be configured by performing fluorine-based coating on the inner peripheral surface or outer peripheral surface of the rubber-based materials or both surfaces thereof. In that case, slidability to a member coming into contact with the firstprotective tube93A improves.
• The secondprotective tube93B is made of fluorine-based resin with excellent flexibility and slidability, such as polytetrafluoroethylene (PTFE) or a tetrafluoroethylene perfluoroalkyl vinyl ether copolymer (PFA). One end portion of the secondprotective tube93B is inserted into the small-diameter connection part103cof the connectingmember103, and the other end portion thereof is connected to theconnector29A (refer toFIG. 1).
• Since the firstprotective tube93A is made to have a smaller elastic constant than the secondprotective tube93B, the first protective tube is more flexible than the secondprotective tube93B, so that disconnection of theoptical fibers55 can be prevented. Additionally, other built-in components within theendoscope insertion part25 are not damaged.
• Since the elastic constant of the secondprotective tube93B is large, attaining a reduction in diameter without reducing strength will be possible. Since the inner peripheral surface and outer peripheral surface of the secondprotective tube93B have high slidability, the operation of inserting theoptical fiber55 into the tube can be reduced, and entanglement in other built-in components does not occur easily within theendoscope insertion part25.
• The above elastic constant is a parameter showing bending stiffness when each tube is macroscopically observed. The larger elastic constant shows harder bendability, and the smaller elastic constant shows easier bendability and flexibility. Specifically, the elastic constant is expressed by rigidity modulus, tensile modulus, or the like. Here, from the viewpoints of sufficiently securing the assemblability of theendoscope11 and the curving manipulability of thecurvable portion37, and suppressing disconnection of theoptical fiber55, the tensile modulus of the firstprotective tube93A is preferably in the range of 5 to 50 MPa, and the tensile modulus of the secondprotective tube93B is preferably in the range of 100 to 600 MPa. If the tensile modulus is smaller than this range, the protective tube is excessively flexible, and assemblability into theendoscope insertion part25 degrades, and if the tensile modulus is larger than this range, flexibility decreases and curvability is impaired. Additionally, the tensile modulus of the secondprotective tube93B is preferably 2 to 20 times larger than the tensile modulus of the firstprotective tube93A. Thereby, the curvability in thecurvable portion37 and assemblability into theendoscope insertion part25 can be properly made compatible.
• Additionally, the external diameter of the firstprotective tube93A is larger than that of the secondprotective tube93B, and the external diameter from the distal end light-projectingportion91 to the secondprotective tube93B is adapted to become smaller in a stepwise fashion. Thereby, the handlability in a single body of thelight guide unit81 becomes good, and assembling operation into theendoscope insertion part25 becomes easy. Additionally, since the overallprotective tube93 can be formed so as to have a small diameter, reduction in the diameter of theendoscope insertion part25 is not hindered.
• Thelight guide unit81 of the above configuration and are arranged in theendoscope insertion part25 such that a region S1 of the firstprotective tube93A and a region S2 of the secondprotective tube93B are made to correspond to a region of thecurvable portion37 of theendoscope insertion part25 and a region of thesoft portion35, respectively. That is, the region S1 of the firstprotective tube93A is built at least in the region of thecurvable portion37, and the region of the secondprotective tube93B is built in the region of thesoft portion35.
• An explanatory view showing the arrangement relationship between the endoscope insertion part and the light guide unit is shown inFIG. 8. Thelight guide unit81 has the distal end light-projectingportion91 fixed to the distal endhard portion71 of thedistal end portion39 of theendoscope insertion part25. Additionally, the firstprotective tube93A and the secondprotective tube93B are inserted through a plurality ofjoint rings111 arranged in thecurvable portion37, and reach thesoft portion35. Although the details will be described below, a manipulating wire (not shown) is pulled by the manipulation of the angle knobs33 (refer toFIG. 2) by an operator, and a plurality ofjoint rings111 is turned aboutcoupling shafts113 and115 by the pulling of this manipulating wire.
• As the above arrangement is adopted, and the firstprotective tube93A covers at least theoptical fiber55 in the range of thecurvable portion37, when thecurvable portion37 is curved, the firstprotective tube93A deforms flexibly and absorbs the pressure from a tube lateral face applied to theoptical fiber55. As a result, the buckling of theoptical fiber55 covered with the firstprotective tube93 can is prevented, and occurrence of disconnection can be inhibited. Additionally, since the firstprotective tube93A has high flexibility even when the first protective tube is curved in thecurvable portion37, and abuts on and rubs against other built-in components, other built-in components are not damaged. There is no level difference on the outer surface of thelight guide unit81 in the region of acurvable portion37, and this also does not damage other built-in components. Additionally, since there is no level difference, slidability to other built-in components also improves.
• Since the firstprotective tube93A is formed of a material with a small elastic constant, the first protective tube is apt to bend. Therefore, the resistance against curving operation is little, the manipulation force of turning the angle knobs33 shown inFIG. 2 is small, and the manipulability of the endoscope improves.
• As shown inFIG. 8, thesoft portion35 is adapted to cover acoil117 with atube119. Thecoil117 is fixed at aconnection place123 between thesoft portion35 and thecurvable portion37 by a fixingmember121. Therefore, since the fixingmember121 is arranged, the internal diameter of theconnection place123 is relatively small.
• Thus, if the firstprotective tube93A is provided to extend into the region of thesoft portion35 where theconnection place123 is avoided, and is connected to the connectingmember103 at a position where the first protective tube is inserted into thesoft portion35, degradation of slidability caused by interference with a smaller-diameter portion of theconnection place123 or degradation of the curving manipulability of thecurvable portion37 can be prevented. That is, thelight guide unit81 can smoothly slide without being caught in the fixingmember121 of theconnection place123, and degradation of flexibility caused by the presence of the connectingmember103 does not reach thecurvable portion37.
• Additionally, as shown inFIG. 9A, even when a plurality oflight guide units81A and81B are built in theendoscope insertion part25, the connectingmember103 interposed between the firstprotective tube93 and the secondprotective tube93B is provided at an axial position shifted into thesoft portion35 by a distance L1 from the end of thesoft portion35 on the side of thecurvable portion37 in such a manner to avoid theconnection place123. This can prevent degradation of the slidability of thelight guide units81A and81B or degradation of the curving manipulability of thecurvable portion37.
• Moreover, as shown inFIG. 9B, the same effects as above are obtained by providing the connectingmember103 that becomes the connection part between the firstprotective tube93A and the secondprotective tube93B at an axial position different for each of thelight guide units81A and81B. Additionally, occurrence of a bias in the curving stiffness of thesoft portion35 caused by overlap of the connectingmembers103 of the respectiveprotective tubes93A and93B can be prevented.
• Theprotective tube93 has a surface friction coefficient of thesecond region93B smaller than the surface friction coefficient of thefirst region93A. This can makes the slidability of the secondprotective tube93B, which is longer than the firstprotective tube93A, excellent over its entire length. Hence, the workability when theoptical fiber55 is inserted through the tube improves, and entanglement in other built-in components in thesoft portion35 can be made difficult.
• Next, the effects caused by covering an optical fiber in the region of thecurvable portion37 with the firstprotective tube93A will be further described.
• FIG. 10 is a schematic explanatory view showing a case where bending has occurred in a portion of the light guide unit when a curvable portion is curved. In thecurvable portion37 formed between thedistal end portion39 and thesoft portion35, the plurality ofjoint rings111 mentioned above are coupled together about thecoupling shafts113 and115, respectively, that are turnable to each other. The plurality ofjoint rings111 can be curved in a desired direction by the pulling of the manipulating wire by the manipulation of an angle knob.
• Apivot pin125 is arranged in the coupling shaft113 (115 is the same), which couples the adjacentjoint rings111 together, to couple both thejoint rings111 turnably. A throughhole127 is formed in ahead125aof thepivot pin125 that protrudes toward the center of thejoint ring111, and the manipulatingwire129 is inserted through the throughhole127.
• Various kinds of built-in components including thelight guide unit81 are received inside the joint rings111, and the respective built-in components are also curved along thecurvable portion37 with the curving operation of thecurvable portion37. In that case, the protrudinghead125aof thepivot pin125 may be pressed against the firstprotective tube93A of thelight guide unit81, and the firstprotective tube93A may be bent with a small curvature radius. Bending generated in the firstprotective tube93A induces disconnection of theoptical fiber55 inserted through the tube.
• However, in the firstprotective tube93A of the present configuration, as previously described, the thickness t that can be found as ½ of the difference between the external diameter D and the internal diameter d is made larger than the greatest curvature radius r_maxat which theoptical fiber55 breaks due to bending as shown in the cross-sectional view of the firstprotective tube93A inFIG. 11. Thereby, even when theprotective tube93A is bent at 180° as shown inFIG. 12, and is bent with a minimum curvature radius, the curvature radius r of theoptical fiber55 becomes always larger than the curvature radius r_maxat which breaking occurs. Accordingly, according to this configuration, disconnection does not occur in theoptical fiber55 by any manipulations of thecurvable portion37.
• As described above, the present invention is not limited to the above embodiment. Changing or applying the present invention by those skilled in the art on the basis of the description of the specification, or well-known techniques are scheduled by the present invention and is included within a range where protection is required. For example, although the protective tube is provided to cover the outside of theoptical fiber55 in this configuration example, the protective tube may cover not only theoptical fiber55, but also other built-in components, such as theforceps tube79, the air supply andwater supply tube89, and thesignal cable51 shown inFIG. 6. Additionally, the global elastic constant (bending stiffness) of the protective tube may be made different by making the shapes of the first region and the second region different from each other in addition to changing the elastic constant by selection of materials. Additionally, the protective tube may be a tube made by two-color molding or insert molding of materials with different elastic constants in addition to the configuration in which a plurality of tube members are coupled together. Thereby, the connectingmember103 becomes unnecessary, reliability improves, and maintenance becomes easy.
• As described above, the following matters are disclosed in the present specification.
• (1) An endoscope including a curvable portion provided to extend at a distal end of a soft portion having flexibility, an elongated insertion part to be inserted into a subject, an elongated flexible body built in the insertion part, and a protective tube that covers an outer periphery of the flexible body, the protective tube having a first region that covers the flexible body located at least in the curvable portion, and a second region that covers the flexible body located in the soft portion, and the elastic constant of the first region being smaller than the elastic constant of the second region, and the external diameter of the protective tube in the first region being larger than the external diameter of the protective tube of the second region.
• According to this endoscope, there is provided an endoscope in which the elastic constant of the first region of the protective tube is set to a value smaller than the elastic constant of the second region, and the external diameter of the protective tube in the first region is made larger than the external diameter of the protective tube of the second region. Thereby, when the curvable portion is curved, the first region deforms flexibly at a radius that is equal to or more than the greatest radius of rotation at which the flexible body breaks, so that the pressure from the lateral face applied to the flexible body can be absorbed. As a result, the flexible body can be prevented from buckling. Additionally, even if the first region of the protective tube is curved in the curvable portion and abuts on other built-in components, since the first region has high flexibility, other built-in components are not damaged. Moreover, as the first region with a small elastic constant is arranged at least in the region of the curvable portion, resistance against the curving operation of the curvable portion decreases and curving manipulability improves.
• (2) The endoscope of (1) in which the first region and the second region are made of different materials, respectively.
• According to this endoscope, the elastic constant can be simply made different by forming the first region and second region of the protective tube of different materials, respectively.
• (3) The endoscope of (2) in which the first region is made of a rubber-based material.
• According to this endoscope, the rubber-based material is applied to the first region, so that flexibility is enhanced and the flexible body can be protected from the pressure from a lateral face. Additionally, the flexible body can be maintained in a straight shape by an elastic restoring force, and assemblability when the flexible body is inserted into the insertion part improves.
• (4) The endoscope of (2) in which the first region is provided by performing fluorine-based coating on the surface of the rubber-based material.
• According to this endoscope, the fluorine-based coating is performed on the surface of the rubber-based material, so that slidability with the flexible body inserted into the inner surface of the first region, or other built-in components that touch the outer surface becomes good, and the curving manipulability or assemblability of the curvable portion can be improved.
• (5) The endoscope of (3) or (4) in which the rubber-based material includes either silicone rubber or fluorine-based rubber.
• According to this endoscope, a rubber material that has high flexibility and is chemically stable is used for the first region, so that the rubber material does not alter even if the endoscope is touched by cleaning chemicals when being washed, and also has little degradation with time.
• (6) The endoscope of any one of (2) to (5) in which the second region of the protective tube is made of a fluorine-based resin material.
• According to this endoscope, the fluorine-based resin material is applied to the second region, so that slidability with the flexible body inserted into the inner surface of the second region, or other built-in components that touch the outer surface becomes good, and assemblability of the soft portion improve.
• (7) The endoscope of (6) in which the fluorine-based resin material includes either polytetrafluoroethylene (PTFE) or a tetrafluoroethylene perfluoroalkyl vinyl ether copolymer (PFA).
• According to this endoscope, high slidability can be obtained in the second region of the protective tube.
• (8) The endoscope of any one of (1) to (7) in which the tensile modulus of the first region is in the range of 5 to 50 MPa, and the tensile modulus of the second region is in the range of 100 to 600 MPa.
• According to this endoscope, the assemblability of the endoscope and the curving manipulability of the curvable portion can be sufficiently secured.
• (9) The endoscope of any one of (1) to (8) in which the tensile modulus of the second region is 2 to 20 times larger than the tensile modulus of the first region.
• According to this endoscope, the assemblability of the endoscope and the curving manipulability of the curvable portion can be sufficiently secured.
• (10) The endoscope according to any one of (1) to (9) in which the first region and of the second region of the protective tube are constituted by separate tube members, respectively, and a connection part of the tube member between the first region and the second region is arranged in the soft portion.
• According to this endoscope, the connection part of the tube member is arranged in the soft portion, so that degradation of slidability in the curvable portion or degradation of the curving manipulability of the curvable portion can be prevented.
• (11) The endoscope of (10) in which a plurality of the flexible bodies covered with the protective tube is arranged inside the insertion part, and the connection part between the first region and the second region of the protective tube is arranged at an axially different position for each of the protective tubes.
• According to this endoscope, a bias can be prevented from occurring in the curving stiffness of the soft portion due to overlap of the connection parts of the respective protective tubes.
• (12) The endoscope of any one of (1) to (12) in which surface friction coefficient of the second region of the protective tube is smaller than the surface friction coefficient of the first region.
• According to this endoscope, the slidability in the second region of the protective tube becomes good, the workability when the flexible body is inserted into the tube can be improved, and the slidability between other built-in components in the soft portion and the protective tube can be improved.
• (13) The endoscope of any one of (1) to (12) in which the flexible body is an optical fiber that transmits illumination light to the distal end of the insertion part.
• According to this endoscope, disconnection of an optical fiber can be prevented.

Claims (24)

1. An endoscope comprising:

a curvable portion provided to extend at a distal end of a soft portion having flexibility,

an elongated insertion part to be inserted into a subject,

an elongated flexible body built in the insertion part, and

a protective tube that covers an outer periphery of the flexible body,

wherein the protective tube has a first region that covers the flexible body located at least in the curvable portion, and a second region that covers the flexible body located in the soft portion, and

wherein the elastic constant of the first region is smaller than the elastic constant of the second region, and the external diameter of the protective tube in the first region is larger than the external diameter of the protective tube in the second region.

2. The endoscope according toclaim 1,

wherein the first region and the second region are made of different materials.

3. The endoscope according toclaim 2,

wherein the first region is made of a rubber-based material.

4. The endoscope according toclaim 3,

wherein the surface of the rubber-based material of the first region is coated with fluorine-based coating.

5. The endoscope according toclaim 3,

wherein the rubber-based material includes either silicone rubber or fluorine-based rubber.

6. The endoscope according to any one ofclaim 2,

wherein the second region is made of a fluorine-based resin material.

7. The endoscope according to any one ofclaim 3,

wherein the second region is made of a fluorine-based resin material.

8. The endoscope according toclaim 6,

wherein the fluorine-based resin material includes either polytetrafluoroethylene (PTFE) or a tetrafluoroethylene perfluoroalkyl vinyl ether copolymer (PFA).

9. The endoscope according to any one ofclaim 1,

wherein the elastic constant is tensile modulus, the tensile modulus of the first region is in the range of 5 to 50 MPa, and the tensile modulus of the second region is in the range of 100 to 600 MPa.

10. The endoscope according to any one ofclaim 2,

wherein the elastic constant is tensile modulus, the tensile modulus of the first region is in the range of 5 to 50 MPa, and the tensile modulus of the second region is in the range of 100 to 600 MPa.

11. The endoscope according to any one ofclaim 3,

wherein the elastic constant is tensile modulus, the tensile modulus of the first region is in the range of 5 to 50 MPa, and the tensile modulus of the second region is in the range of 100 to 600 MPa.

12. The endoscope according to any one ofclaim 1,

wherein the tensile modulus of the second region is 2 to 20 times larger than the tensile modulus of the first region.

13. The endoscope according to any one ofclaim 2,

wherein the tensile modulus of the second region is 2 to 20 times larger than the tensile modulus of the first region.

14. The endoscope according to any one ofclaim 3,

wherein the tensile modulus of the second region is 2 to 20 times larger than the tensile modulus of the first region.

15. The endoscope according to any one ofclaim 1,

wherein the protective tube in the first region and the protective tube in the second region are constituted by separate tube members, and

a connection part between the tube member of the first region and the tube member of the second region is arranged in the soft portion.

16. The endoscope according to any one ofclaim 2,

wherein the protective tube in the first region and the protective tube in the second region are constituted by separate tube members, and

a connection part between the tube member of the first region and the tube member of the second region is arranged in the soft portion.

17. The endoscope according to any one ofclaim 3,

wherein the protective tube in the first region and the protective tube in the second region are constituted by separate tube members, and

a connection part between the tube member of the first region and the tube member of the second region is arranged in the soft portion.

18. The endoscope according toclaim 10,

wherein a plurality of the flexible bodies covered with the protective tube is arranged inside the insertion part, and

the connection part between a protective tube member of the first region and a protective tube member of the second region is arranged at an axially different position for each of the protective tubes.

19. The endoscope according to any one ofclaim 1,

wherein the surface friction coefficient of the second region is smaller than the surface friction coefficient of the first region.

20. The endoscope according to any one ofclaim 2,

wherein the surface friction coefficient of the second region is smaller than the surface friction coefficient of the first region.

21. The endoscope according to any one ofclaim 3,

wherein the surface friction coefficient of the second region is smaller than the surface friction coefficient of the first region.

22. The endoscope according to any one ofclaim 1,

wherein the flexible body is an optical fiber that transmits illumination light to the distal end of the insertion part.

23. The endoscope according to any one ofclaim 2,

wherein the flexible body is an optical fiber that transmits illumination light to the distal end of the insertion part.

24. The endoscope according to any one ofclaim 3,

wherein the flexible body is an optical fiber that transmits illumination light to the distal end of the insertion part.

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