Bending mechanism and endoscope

Abstract

A bending mechanism (20) is provided with a first tube (2b), a first guide (24), and a second guide (22). The first tube (2b) is formed along the axis (O) and bends as a result of pulling a wire (23). The first guide (24) is cylindrically formed by a resin, is provided to the first tube (2b) along the axis (O), and holds the wire (23). The second guide (22) is fixed to the first tube (2b) and holds the first guide (24).

Description

Bending mechanism and endoscope

[0001] The present invention relates to a bending mechanism that is bent by pulling a wire, and an endoscope that is equipped with the bending mechanism.

[0002] Endoscopes equipped with bending mechanisms capable of changing the direction of the distal end have been proposed. The bending mechanism is configured by connecting multiple bending pieces so that they can swing and arranging them in a bending section, and fixing the distal end of a bending wire to the bending piece located at the distal end, for example. The bending wire is inserted into a wire receiver provided on the bending piece in the bending section. The bending wire is inserted into a tubular portion on the proximal end side of the bending section, and the proximal end side of the bending wire is connected to a drum or the like in the operation section. The drum in the operation section rotates in conjunction with a bending operation knob, pulling the bending wire. As a result, the bending section is bent by operating the bending operation knob.

[0003] For example, International Publication WO2016-167099 describes an endoscope bending tube in which multiple ring members are connected using multiple tubular members. Specifically, the technology described in this publication employs a configuration in which multiple bending pieces are connected using tubular members, instead of the general configuration in which multiple bending pieces are connected using hinges or the like.

[0004] When the insertion section of an endoscope is inserted into a subject, the bending section may take on a complex shape such as a loop. If the bending wire is pulled in this state, friction or snagging occurs between the bending wire and the wire receiver, increasing sliding resistance.

[0005] This causes the traction force of the bending wire to be lost in the wire receiver, and the amount of operating force required to operate the bending operation knob increases in accordance with the sliding resistance, resulting in reduced operability.In addition, the corners of the wire receiver that come into contact with the bending wire may become worn or chipped.

[0006] In response to this, a technique is known in which a powder lubricant is used to reduce sliding resistance, thereby enabling easy bending operation with a small amount of operating force.

[0007] Endoscopes are generally manufactured in controlled areas such as clean rooms, but powder lubricants cannot be brought into such controlled areas. Therefore, using powder lubricants reduces manufacturing flexibility, increases manufacturing costs, and complicates the construction of assembly lines.

[0008] The present invention has been made in view of the above circumstances, and has as its object to provide an inexpensive bending mechanism that can be easily bent with a small amount of operating force, and an endoscope equipped with the bending mechanism.

[0009] A bending mechanism according to one aspect of the present invention comprises a first tube formed along an axis extending from a first side to a second side and configured to be bent by pulling a wire, a first guide formed in a cylindrical shape from resin and provided on the first tube along the axis to hold the wire, and a second guide fixed to the first tube to hold the first guide.

[0010] An endoscope according to one aspect of the present invention comprises an insertion section configured to be inserted into a subject, an operating section provided on a first side of the insertion section, and a bending mechanism at least a portion of which is provided on a second side of the insertion section, wherein the bending mechanism comprises: a first tube formed along an axis extending from the first side to the second side and configured to be bent by pulling a wire; a first guide formed in a cylindrical shape from resin and provided in the first tube along the axis, which holds the wire; and a second guide fixed to the first tube, which holds the first guide, and the first side of the wire is connected to the operating section.

[0011] FIG. 1 is a diagram illustrating an example of the configuration of an endoscope according to each embodiment of the present invention; FIG. 2 is a perspective view illustrating an example of a flexible tube according to a first example of related art; FIG. 3 is a perspective view illustrating a modified example of the flexible tube according to the first example of related art; FIG. 4 is a diagram illustrating the configuration of the outer circumferential surface of the flexible tube according to the first example of related art when developed into a plane; FIG. 5 is a diagram illustrating the configuration of the outer circumferential surface of the flexible tube according to the second example of related art when developed into a plane; FIG. 6 is a perspective view illustrating a flexible tube according to a third example of related art; FIG. 7 is a diagram illustrating the configuration of the outer circumferential surface of the flexible tube according to the third example of related art when developed into a plane; FIG. 8 is a diagram illustrating the configuration of the outer circumferential surface of the flexible tube according to the fourth example of related art when developed into a plane; FIG. 9 is a diagram illustrating the configuration of the outer circumferential surface of the flexible tube according to the fifth example of related art when developed into a plane; FIG. 10 is a diagram illustrating the configuration of the outer circumferential surface of the flexible tube according to the sixth example of related art when developed into a plane; FIG. 11 is a diagram illustrating the configuration of the outer circumferential surface of the flexible tube according to the seventh example of related art when developed into a plane; FIG. 12 is a diagram illustrating the configuration of the outer circumferential surface of the flexible tube according to the eighth example of related art when developed into a plane; and FIG. 13 is a diagram illustrating the configuration of the outer circumferential surface of the flexible tube according to the ninth example of related art when developed into a plane. 10 is a diagram showing the configuration of an outer circumferential surface of a flexible tube according to a tenth example of the related art when developed into a plane. FIG. 11 is a perspective view showing a flexible tube according to an eleventh example of the related art. FIG. 12 is a perspective view showing a flexible tube according to a twelfth example of the related art. FIG. 13 is a perspective view showing a flexible tube according to a thirteenth example of the related art. FIG. 14 is a cross-sectional view showing an example of the configuration of a bending wire in a bending portion according to a first embodiment of the present invention. FIG. 15 is a partial perspective view showing an example of the configuration of a bending wire in a bending portion according to the first embodiment. FIG. 16 is a diagram showing a comparison of the relationship between a bending wire and a wire receiver inserted inside a tube in the first embodiment with the relationship between a conventional bending wire and a wire receiver. FIG. 17 is a cross-sectional view showing the configuration of a tube through which a bending wire is inserted in a bending portion in a straight state in the first embodiment. FIG. 18 is a cross-sectional view showing a state of a tube through which a bending wire is inserted in a bending portion in a maximally bent state in the first embodiment. FIG. 19 is a cross-sectional view parallel to a central axis showing a modified example of a partial tube constituting an intermittent tube in the second embodiment.FIG. 10 is a cross-sectional view perpendicular to the central axis, showing the configuration of a tube through which a bending wire is inserted in a third embodiment of the present invention. FIG. 11 is a diagram showing a configuration example when a wire receiver is provided integrally with a bending unit in a fourth embodiment of the present invention. FIG. 12 is a diagram showing the configuration of a tube through which a bending wire is inserted in a fifth embodiment of the present invention. FIG. 13 is a diagram showing the configuration of a tube through which a bending wire is inserted in a sixth embodiment of the present invention. FIG. 14 is a diagram showing the configuration of a tube through which a bending wire is inserted in a seventh embodiment of the present invention. FIG. 15 is a diagram showing the state of a tube when a bending portion is bent in an eighth embodiment of the present invention. FIG. 16 is a perspective view showing a first configuration example of a tube in the eighth embodiment. FIG. 17 is a diagram showing a cross-section and a partially enlarged side view of the tube in the first configuration example in the eighth embodiment. FIG. 18 is a perspective view showing a second configuration example of a tube in the eighth embodiment. FIG. 19 is a diagram showing a cross-section and a partially enlarged side view of the tube in the second configuration example in the eighth embodiment. FIG. 19 is a partial perspective view showing the configuration of a wire receiver in a bending unit of a ninth embodiment of the present invention. FIG. 19 is a partial perspective view showing the configuration of a wire receiver in a bending unit of a modified example of the ninth embodiment.

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the embodiments described below.

[0013] In the drawings, the same or corresponding elements are appropriately designated by the same reference numerals. It should be noted that the drawings are schematic, and that the length relationships, length ratios, and quantities of elements within a single drawing may differ from reality in order to simplify the description. Furthermore, there may be cases where the length relationships, ratios, quantities, and the like differ between multiple drawings.

[0014] FIG. 1 is a diagram showing an example of the configuration of an endoscope 1 according to each embodiment of the present invention.

[0015] The endoscope 1 is a device for observing and treating a subject. The endoscope 1 includes an insertion section 2 that is inserted into the subject, an operation section 3 that is provided on the proximal end side (first side: the proximal direction P side in FIG. 21 ) of the insertion section 2, and a universal cord 4 that extends from the operation section 3.

[0016] The subject into which the insertion portion 2 is inserted is assumed to be a living being such as a human or animal, but is not limited thereto and may be an inanimate object such as a machine or a building. The endoscope 1 may also be an automatically inserted endoscope that advances and retreats by rotating. The endoscope 1 may be an upper gastrointestinal endoscope, a lower gastrointestinal endoscope, or an endoscope for use in other regions.

[0017] The insertion section 2 includes, in order from the tip to the base end, a tip section 2a, a bending section 2b (bending tube, first tube), and a tubular section 2c (second tube).

[0018] The tip 2a includes, for example, an observation system and an illumination system. The illumination system includes an illumination optical system and the like, and irradiates the specimen with illumination light. The observation system includes an objective optical system and an image sensor inside an observation window. The observation system forms an image of the return light from the specimen using the objective optical system, and captures the image using the image sensor.

[0019] The bending portion 2b is provided on the proximal end side of the distal end portion 2a and is configured to be bendable, for example, in two directions (up and down) or in four directions (up, down, left, and right). When the bending portion 2b is bent, the direction of the distal end portion 2a changes, and the direction of observation by the observation system and the direction of illumination light emitted by the illumination system change. The bending portion 2b is also bent to improve the insertability of the insertion portion 2 inside the subject.

[0020] The tubular portion 2c is a tubular portion that connects the base end of the bending portion 2b and the tip of the operation portion 3. The tubular portion 2c has a flexible form that bends according to the shape of the subject into which it is inserted. In this case, the endoscope 1 is called a flexible endoscope.

[0021] The operation unit 3 is provided on the proximal end side of the insertion portion 2 and is a portion that is held by hand to perform various operations related to the endoscope 1. The operation unit 3 includes, for example, a grip portion 3a, a bending operation knob 3b, a plurality of operation buttons 3c, and a treatment tool insertion port 3d.

[0022] The grip portion 3a is a portion where the operator grips the endoscope 1 with the palm of his / her hand.

[0023] The bending operation knob 3b is an operation device for bending the bending portion 2b using, for example, the thumb of the hand holding the grip portion 3a. When the bending portion 2b can be bent in four directions, up, down, left, and right, the bending operation knob 3b includes a UD bending operation knob 3b1 for bending in the up and down direction and an RL bending operation knob 3b2 for bending in the left and right direction.

[0024] The plurality of operation buttons 3c include, for example, an air / water supply button 3c1, a suction button 3c2, and other buttons 3c3.

[0025] The air / water supply button 3c1 is a button for supplying air and water to an observation window provided on the tip surface of the observation system via an air / water supply channel (not shown) to clean the observation window.

[0026] The suction button 3c2 is a button for performing an operation to suction liquid, mucous membrane, etc. from inside the subject via a suction channel (not shown).

[0027] The other buttons 3c3 are used, for example, as a freeze button for pausing the monitor screen, a release button for capturing a still image, a button for switching to special light, and the like.

[0028] The treatment tool insertion port 3d is provided on the side surface of the distal end of the gripping portion 3a. The treatment tool insertion port 3d communicates with a treatment tool channel. The treatment tool channel has a distal end opening at the distal end portion 2a. When various treatment tools such as forceps are inserted through the treatment tool insertion port 3d, the tip of the treatment tool protrudes from the distal end opening of the treatment tool channel, allowing various treatments to be performed on the subject.

[0029] The universal cord 4 extends, for example, from the side surface on the proximal end side of the operation unit 3. A connector 4a is provided at the extending end of the universal cord 4. The connector 4a is connected to an endoscope processor and a light source device (or an endoscope processor that also serves as a light source device), not shown.

[0030] The endoscope processor transmits drive signals and power to the imaging element in the distal end portion 2a. The endoscope processor also receives an imaging signal obtained by imaging the subject with the imaging element. The light source device emits illumination light and transmits it via a light guide (not shown). The illumination light transmitted through the light guide is irradiated from the distal end surface of the distal end portion 2a toward the subject.

[0031] In addition, instead of a configuration in which the illumination light emitted by the light source device is transmitted through a light guide, a configuration in which a light-emitting element is provided within the tip portion 2a, power is supplied to the light-emitting element from the endoscope processor, and the light-emitting element emits the illumination light may be adopted.

[0032] Next, the flexible tube 5 used in the endoscope 1 will be described as a related art with reference to FIGS.

[0033] Corrugated tubes have been known as flexible tubes. Corrugated tubes have a bellows structure in which ring-shaped convex portions and ring-shaped concave portions are alternately formed around the longitudinal center axis. Corrugated tubes are inexpensive to manufacture and have high flexibility, making them suitable for use as covering materials for electric wires, for example.

[0034] Flexible endoscopes have an insertion section that is configured as a flexible tube. In contrast, single-use endoscopes that are discarded after a single use have been proposed in recent years. From a cost perspective, it is preferable that single-use endoscopes be inexpensive to manufacture, and the use of corrugated tubes has been considered.

[0035] In general, the characteristics required for the insertion section of an endoscope include flexibility, stretch resistance, and torque resistance. As is well known, flexibility is the ability to bend. Stretch resistance is resistance to stretching. Specifically, stretch resistance includes compression resistance, which is resistance to compression, and tension resistance, which is resistance to tension. Torque resistance is resistance to twisting around the central axis.

[0036] Corrugated tubes with a bellows structure are flexible and have high torque resistance. However, they have low resistance to expansion and contraction, so they shrink when subjected to compressive force and stretch when subjected to tensile force.

[0037] The aforementioned properties often have a trade-off relationship. For this reason, it is difficult for a corrugated tube with a bellows structure to improve its resistance to stretching and torque while maintaining its flexibility. It is also difficult for a corrugated tube with a bellows structure to freely control its properties, such as viscoelasticity, when bent.

[0038] In the following related art, an endoscope having a flexible tube that can be manufactured inexpensively by balancing bendability, resistance to stretching, and resistance to torque will be described.

[0039] 2 to 4 show a first example of the related art. Fig. 2 is a perspective view showing an example of a flexible tube 5 of the first example of the related art.

[0040] The endoscope 1 includes a flexible tube 5. The flexible tube 5 is provided, for example, in the insertion section 2 of the endoscope 1 (i.e., the portion including the bending section 2b and the tubular section 2c). However, this is not a limitation, and the flexible tube 5 may also be provided in the universal cord 4. Furthermore, the flexible tube 5 is not limited to use in the endoscope 1, and can be widely applied to medical devices. For example, the flexible tube 5 may be applied to treatment instruments such as catheters, overtubes, and the like.

[0041] The flexible tube 5 is a flexible tube extending from one end to the other along a center axis O. The flexible tube 5 has, on its outer circumferential surface 5A, a plurality of convex surfaces 6 and a concave surface 7 defined by the plurality of convex surfaces 6. The concave surface 7 has a bottom and is different from a slit.

[0042] The flexible tube 5 is formed by feeding a heated material such as plastic from an extruder into a cylindrical mold and then using a vacuum mechanism installed in the mold to force the material into close contact with the inner circumferential surface of the mold. The cylindrical mold may be, for example, a pair of molds divided into two by a plane passing through the central axis. The pair of molds may be transported, for example, in an endless track manner.

[0043] Therefore, the shapes of the convex surface 6 and the concave surface 7 formed on the outer peripheral surface 5A of the flexible tube 5 are precisely defined by the mold. On the other hand, the concave and convex shapes on the inner peripheral surface 5B (see FIG. 4) of the flexible tube 5 are roughly formed by the material that is tightly adhered to the flexible tube 5 so as to have a substantially constant thickness. In other words, when viewed from the inner peripheral surface 5B of the flexible tube 5, the portion corresponding to the convex surface 6 is concave, and the portion corresponding to the concave surface 7 is convex.

[0044] The multiple convex surfaces 6 are isolated from one another by being surrounded by the concave surfaces 7. In other words, the multiple convex surfaces 6 are formed discontinuously in the axial direction parallel to the central axis O and in the circumferential direction around the central axis O.

[0045] Each of the multiple convex surfaces 6 has, for example, the same shape (an example of a configuration having multiple shapes will be described later) and is periodically arranged along the outer circumferential surface 5A of the flexible tube 5. When the outer circumferential surface 5A of the flexible tube 5 is developed into a plane, each of the multiple convex surfaces 6 forms a polygon, and in this case, a rectangle in particular.

[0046] 2, each of the multiple convex surfaces 6 is a diamond-shaped convex surface 6a that forms a diamond when the outer circumferential surface 5A of the flexible tube 5 is developed into a plane. Note that, hereinafter, a "diamond-shaped convex surface" will be referred to simply as a "diamond," and the term "convex surface" will be omitted. Similarly, convex surfaces of other shapes described below will also be described without the term "convex surface."

[0047] As is well known, the rhombus 6a has four sides of the same length. Except in the case of a square, one of the two diagonals of the rhombus 6a is longer than the other.

[0048] The convex surface 6 and the concave surface 7 are formed, for example, in a shape that is plane-symmetrical with respect to a plane passing through the central axis O. This makes it easy to remove the mold when molding using a mold divided into two parts.

[0049] FIG. 3 is a perspective view showing a modified example of the flexible tube 5 of the first example of the related art.

[0050] For example, if the diameter of the flexible tube 5 shown in Fig. 2 and the diameter of the flexible tube 5 shown in Fig. 3 are the same, the area of ​​the diamond 6a' shown in Fig. 3 is relatively smaller than the area of ​​the diamond 6a shown in Fig. 2. While two diamonds 6a shown in Fig. 2 are arranged in the circumferential direction, for example, four diamonds 6a' shown in Fig. 3 are arranged in the circumferential direction. The number of convex surfaces 6 arranged in the circumferential direction is not limited to an even number and may be an odd number, or any appropriate number.

[0051] 4 is a diagram showing the configuration of the outer circumferential surface 5A of the flexible tube 5 according to the first example of the related art when the outer circumferential surface 5A is unfolded onto a plane. Note that FIG. 4 also shows an axial cross section and a circumferential cross section of the flexible tube 5 unfolded onto a plane.

[0052] The rhombus 6a in the example of Figure 2 is tiled periodically so that, for example, the longer diagonal is parallel to the axial direction (the direction of arrow A shown in Figure 4) (however, this is a tiling excluding the concave surface 7, and the same applies below).

[0053] As a result, all of the concave surfaces 7 are inclined with respect to the axial direction and with respect to the circumferential direction (the direction perpendicular to the arrow A in the developed view of FIG. 4).

[0054] Specifically, the concave surface 7 includes a first inclined portion 7a1 inclined at an angle α with respect to the axial direction and a second inclined portion 7a2 inclined at an angle −α with respect to the axial direction, where α is an angle of 45° or less. The first inclined portion 7a1 and the second inclined portion 7a2 each constitute the spiral concave surface 7 of the flexible tube 5.

[0055] It should be noted that α is not limited to being equal to or smaller than 45°, and may be set to an angle greater than 45° depending on design needs.

[0056] For example, if α is set to 45° or less, the torque resistance will be slightly lower than when the angle is set to more than 45°, but the resistance to expansion and contraction will be higher. Therefore, when emphasis is placed on suppressing the expansion and contraction of the flexible tube 5 when subjected to a compressive force or a tensile force, it is advisable to set α to 45° or less.

[0057] Conversely, when α is set to be greater than 45°, the resistance to expansion and contraction is slightly lower than when the angle is set to be 45° or less, but the resistance to torque is improved. Therefore, when emphasis is placed on suppressing twisting of the flexible tube 5 when subjected to a twisting force around the central axis O, it is advisable to set α to be greater than 45°.

[0058] In this way, by controlling the angle α, it is possible to control the balance between the stretch resistance and torque resistance, which are in a trade-off relationship.

[0059] As shown in the cross section of FIG. 4, the recessed surface 7 may be filled with a filling material to form a filling structure portion 9 .

[0060] That is, the flexible tube 5 may include a tube body 8 and a filling structure portion 9 .

[0061] The pipe body 8 is formed using a material with a first Young's modulus by the above-described mold so as to have a plurality of convex surfaces 6 and concave surfaces 7 .

[0062] The filling structure portion 9 is formed by filling the concave surface 7 of the pipe body 8 with a filling material having a second Young's modulus lower than the first Young's modulus.

[0063] In this case, the filling rate of the filling material in the filling structure portion 9 may be varied along the axial direction. In the example shown in the axial cross section of Figure 4, the filling rate decreases in the order of the base end filling structure portion 9a, the intermediate filling structure portion 9b, and the tip end filling structure portion 9c in the axial direction.

[0064] As shown in the circumferential cross section of Fig. 4, the filling rate of the filler material in the circumferential direction is constant. However, the filling rate of the filler material in the circumferential direction may be changed to vary the ease of bending depending on the bending direction.

[0065] 4, the radial distance from the concave surface 7 to the convex surface 6 around the central axis O (the depth of the concave surface 7 relative to the convex surface 6, or the height of the convex surface 6 relative to the concave surface 7) may be varied depending on the position of the concave surface 7 on the flexible tube 5. In the example of FIG. 4, the depth of the concave surface 7 at the position where the filling structure portion 9c is provided is deeper than the depth of the concave surface 7 at the positions where the filling structure portions 9a and 9b are provided. Note that the depth from the convex surface 6 to the concave surface 7 may be varied depending on the angle of the concave surface 7 with respect to the axial direction.

[0066] In this way, by providing a filling structure portion 9 and adjusting the depth of the concave surface 7 according to its position on the flexible tube 5, it is possible to more freely control the flexibility of the flexible tube 5 and its properties such as viscoelasticity when bent.

[0067] According to a first example of the related art, the flexible tube 5 is structured to have a plurality of convex surfaces 6 that are isolated from one another and are surrounded by concave surfaces 7. This allows the flexible tube 5 of this example to achieve characteristics that cannot be achieved with a corrugated tube having a bellows structure in which ring-shaped convex portions and ring-shaped concave portions are formed alternately along the direction of the central axis O.

[0068] The flexible tube 5 of this example has a slightly higher surface smoothness than a corrugated tube with a bellows structure. In particular, when the filling structure portion 9 is formed on the concave surface 7, the surface smoothness can be further improved, making the flexible tube 5 more suitable for medical devices such as the endoscope 1 to be inserted into a subject.

[0069] The flexible tube 5 of this example has the concave surface 7 that is inclined with respect to the axial direction and the circumferential direction, and therefore has improved resistance to expansion and contraction while maintaining flexibility.

[0070] The flexible tube 5 of this example allows for more flexible control of the balance between bendability, stretch resistance, and torque resistance. Specifically, various parameters such as the angle α of the concave surface 7 and the depth from the convex surface 6 can be adjusted, providing a high degree of freedom in controlling the characteristics.

[0071] The recessed surface 7 is filled with a filling material having a lower Young's modulus than the tube main body 8 to provide a filling structure portion 9, and the filling rate of the filling structure portion 9 is adjusted depending on the position, thereby imparting elastic deformation characteristics to the flexible tube 5 that differ from those of the tube main body 8. This makes it possible to accommodate, for example, cases where it is desired to change the hardness between the tubular portion 2c and the curved portion 2b. Furthermore, the number of parameters for controlling the characteristics increases, increasing the degree of freedom in optimizing the characteristics of the flexible tube 5.

[0072] The flexible tube 5 of this example can be manufactured inexpensively using an extruder and a mold equipped with a vacuum mechanism, similar to conventional corrugated tubes.

[0073] [Second Example of Related Art] Figure 5 is a diagram showing the configuration of the outer circumferential surface 5A of the flexible tube 5 of a second example of related art when it is developed into a plane. In the second example of related art, parts that are the same as those in the first example of related art are given the same reference numerals, and descriptions thereof will be omitted as appropriate. In the second example of related art, differences from the first example of related art will be mainly described.

[0074] 5, each of the multiple convex surfaces 6 has the same shape, and forms a rectangle 6b when the outer circumferential surface 5A of the flexible tube 5 is developed into a plane. As is well known, the rectangle 6b has a pair of opposing long sides and a pair of opposing short sides, except in the case where all four corners are right angles and the rectangle 6b becomes a square.

[0075] The rectangles 6b constituting the multiple convex surfaces 6 are of two types: rectangles 6b1 whose long sides are arranged from the upper left to the lower right, and rectangles 6b2 whose long sides are arranged from the upper right to the lower left.

[0076] In addition, the concave surface 7 has a first inclined portion 7b1 (the portion surrounded by a dotted line in Figure 5) that is inclined relative to the axial direction along the long side of the rectangle 6b1, and a second inclined portion 7b2 (the portion surrounded by a dotted line in Figure 5) that is inclined relative to the axial direction along the long side of the rectangle 6b2.

[0077] Both ends of the first inclined portion 7b1 abut against the rectangle 6b2. Also, both ends of the second inclined portion 7b2 abut against the rectangle 6b1. Thus, the first inclined portion 7b1 and the second inclined portion 7b2 are formed discontinuously, and their axial lengths are shorter than the axial length of the flexible tube 5. Also, the discontinuously formed first inclined portion 7b1 and second inclined portion 7b2 have a circumferential angle that is smaller than 360°.

[0078] According to the second example of the related art, substantially the same effects as those of the first example of the related art are achieved.

[0079] Furthermore, in the first example of the related art, the spiral-shaped first inclined portion 7a1 and second inclined portion 7a2 are continuous in the axial direction of the flexible tube 5. In contrast, the first inclined portion 7b1 and second inclined portion 7b2 in the second example of the related art are formed discontinuously in the axial direction. This allows the flexible tube 5 of the second example of the related art to have a higher degree of freedom in controlling properties such as bendability, stretch resistance, and torque resistance.

[0080] 5, the rectangles 6b are arranged so that each side is inclined relative to the axial direction, but this is not limiting. A pair of opposing sides of the rectangle 6b may be arranged along the axial direction, and another pair of opposing sides may be arranged along the circumferential direction. Furthermore, the rectangles 6b are not limited to being all the same size, and the sizes of the rectangles 6b may vary depending on the position, etc.

[0081] [Third Example of Related Art] Figures 6 and 7 show a third example of related art. Figure 6 is a perspective view showing a flexible tube 5 of the third example of related art. Figure 7 is a diagram showing the configuration when the outer circumferential surface 5A of the flexible tube 5 of the third example of related art is developed into a plane.

[0082] In the third example of the related art, the same parts as those in the first and second examples of the related art are denoted by the same reference numerals, and the description thereof will be omitted as appropriate. In the third example of the related art, the differences from the first and second examples of the related art will be mainly described.

[0083] 6 and 7 , each of the multiple convex surfaces 6 forms a T-shape 6c when the outer circumferential surface 5A of the flexible tube 5 is developed into a plane. The T-shape 6c is a concave octagon (concave polygon) that has two interior angles (specifically, 270° interior angles) that are reentrant angles (angles greater than 180° and less than 360°) and six other interior angles of 90°.

[0084] The longest side of the T-shape 6c is arranged along the circumferential direction. In this arrangement, the eight sides of the T-shape 6c are parallel to either the axial direction or the circumferential direction. The concave surface 7 includes a first portion 7c1 along the axial direction (in FIG. 7, one first portion 7c1 is shown surrounded by a dotted line) and a second portion 7c2 along the circumferential direction (in FIG. 7, one second portion 7c2 is shown surrounded by a dashed line).

[0085] That is, the concave surface 7 includes at least one of a first portion 7c1 and a second portion 7c2. The first portion 7c1 is formed discontinuously in the axial direction. Therefore, the axial length of the first portion 7c1 is shorter than the axial length of the entire flexible tube 5. The second portion 7c2 is formed discontinuously in the circumferential direction. Therefore, the circumferential length of the second portion 7c2 is shorter than the circumferential length of the outer circumferential surface 5A of the flexible tube 5.

[0086] In this case, the depth of the first portion 7c1 relative to the convex surface 6 may be different from the depth of the second portion 7c2 relative to the convex surface 6. The length of the first portion 7c1 may be different from the length of the second portion 7c2. Furthermore, the width of the first portion 7c1 may be different from the width of the second portion 7c2.

[0087] Among the plurality of T-shapes 6c, two adjacent T-shapes 6c in the circumferential direction are arranged with an axial arrangement pitch offset of 1 / 2 pitch, i.e., the plurality of T-shapes 6c include a T-shape 6c1 and a T-shape 6c2 with an axial arrangement pitch offset of 1 / 2 pitch.

[0088] According to the third example of the related art, substantially the same effects as those of the first and second examples of the related art are achieved.

[0089] According to the third example of the related art, the first portion 7c1 is provided along the axial direction, and the second portion 7c2 is provided along the circumferential direction. Therefore, by adjusting the depth, length, width, etc. of the first portion 7c1 and the second portion 7c2, the degree of freedom in controlling the characteristics can be increased.

[0090] 8 is a diagram showing the configuration of the outer circumferential surface 5A of the flexible tube 5 of a fourth example of the related art when it is developed into a plane. In the fourth example of the related art, parts that are the same as those in the first to third examples of the related art are given the same reference numerals, and descriptions thereof will be omitted as appropriate. In the fourth example of the related art, differences from the first to third examples of the related art will be mainly described.

[0091] 8, each of the multiple convex surfaces 6 forms an L-shape 6d when the outer circumferential surface 5A of the flexible tube 5 is unfolded onto a plane. The L-shape 6d is a concave hexagon (concave polygon) with one concave interior angle (specifically, an interior angle of 270°) and five other interior angles of 90°.

[0092] The L-shape 6d is arranged so that one of its two long sides is axial and the other is circumferential. In this arrangement, the six sides of the L-shape 6d are parallel to either the axial or circumferential direction. The concave surface 7 includes a first portion 7d1 extending along the axial direction (in FIG. 8, one first portion 7d1 is shown surrounded by a dotted line) and a second portion 7d2 extending along the circumferential direction (in FIG. 8, one second portion 7d2 is shown surrounded by a dashed line).

[0093] That is, the concave surface 7 includes at least one of a first portion 7d1 and a second portion 7d2. The first portion 7d1 is formed discontinuously in the axial direction. Therefore, the axial length of the first portion 7d1 is shorter than the axial length of the entire flexible tube 5. The second portion 7d2 is formed discontinuously in the circumferential direction. Therefore, the circumferential length of the second portion 7d2 is shorter than the circumferential length of the outer circumferential surface 5A of the flexible tube 5.

[0094] In this case, the depth of the first portion 7d1 relative to the convex surface 6 may be different from the depth of the second portion 7d2 relative to the convex surface 6. The length of the first portion 7d1 may be different from the length of the second portion 7d2. Furthermore, the width of the first portion 7d1 may be different from the width of the second portion 7d2.

[0095] 8 shows an L-shape 6d having a side along the axial direction and a side along the circumferential direction, but this configuration does not have plane symmetry with respect to a plane including the central axis O. Therefore, the L-shape 6d may be rotated by, for example, 45° to form a V-shape, so that plane symmetry with respect to a plane including the central axis O is achieved.

[0096] According to the fourth example of the related art, substantially the same effects as those of the first to third examples of the related art are achieved.

[0097] According to the fourth example of the related art, the first portion 7d1 is provided along the axial direction and the second portion 7d2 is provided along the circumferential direction, so that the degree of freedom in controlling the characteristics can be increased by adjusting the depth, length, width, etc. of the first portion 7d1 and the second portion 7d2.

[0098] 9 is a diagram showing the configuration of the outer circumferential surface 5A of a flexible tube 5 according to a fifth example of the related art when it is developed into a plane. In the fifth example of the related art, parts that are the same as those in the first to fourth examples of the related art are given the same reference numerals, and descriptions thereof will be omitted as appropriate. In the fifth example of the related art, differences from the first to fourth examples of the related art will be mainly described.

[0099] 9 , each of the multiple convex surfaces 6 forms a rounded polygon when the outer circumferential surface 5A of the flexible tube 5 is developed into a plane. A rounded polygon is roughly a polygon with rounded corners. In this case, each side of the polygon is not limited to a straight line, and may be, for example, a concave arc directed toward the center of the rounded polygon.

[0100] The example shown in Figure 9 specifically shows a rounded triangle 6e (e.g., a rounded equilateral triangle) whose three sides form concave arcs. The rounded triangle 6e is arranged so that the first of its three sides is along the circumferential direction. In this arrangement, the second of the three sides of the rounded triangle 6e forms an angle β with the axial direction, and the third side forms an angle -β with the axial direction. When the rounded triangle 6e is, for example, a rounded equilateral triangle, β = 30° (i.e., 45° or less).

[0101] The concave surface 7 includes a first portion 7e1 along the first side (in Figure 9, one first portion 7e1 is shown surrounded by a dotted line), a second portion 7e2 along the second side (in Figure 9, one second portion 7e2 is shown surrounded by a dashed line), and a third portion 7e3 along the third side (in Figure 9, one third portion 7e3 is shown surrounded by a dashed line).

[0102] The first portion 7e1 is formed discontinuously in the circumferential direction. Therefore, the circumferential length of the first portion 7e1 is shorter than the circumferential length of the outer circumferential surface 5A of the flexible tube 5. The second portion 7e2 and the third portion 7e3 are formed discontinuously in the axial and circumferential directions. Therefore, the axial lengths of the second portion 7e2 and the third portion 7e3 are shorter than the axial length of the entire flexible tube 5. Furthermore, the angular range in the circumferential direction of the second portion 7e2 and the third portion 7e3 is smaller than 360°.

[0103] In this case, the depths of the first portion 7e1, the second portion 7e2, and the third portion 7e3 relative to the convex surface 6 may be different from each other. The lengths of the first portion 7e1, the second portion 7e2, and the third portion 7e3 may also be different from each other. Furthermore, the widths of the first portion 7e1, the second portion 7e2, and the third portion 7e3 may also be different from each other.

[0104] According to the fifth example of the related art, substantially the same effects as those of the first to fourth examples of the related art are achieved.

[0105] According to the fifth example of the related art, the first portion 7e1, the second portion 7e2, and the third portion 7e3 are provided in different directions, and therefore, by adjusting the depth, length, width, and the like of the first portion 7d1, the second portion 7e2, and the third portion 7e3, the degree of freedom in controlling the characteristics can be increased.

[0106] 10 is a diagram showing the configuration of the outer circumferential surface 5A of a flexible tube 5 according to a sixth example of the related art when it is unfolded onto a plane. In the sixth example of the related art, parts that are the same as those in the first to fifth examples of the related art are given the same reference numerals, and descriptions thereof will be omitted as appropriate. In the sixth example of the related art, differences from the first to fifth examples of the related art will be mainly described.

[0107] 10, each of the multiple convex surfaces 6 forms a polygon when the outer circumferential surface 5A of the flexible tube 5 is developed into a plane. In the example shown in FIG. 10, the convex surfaces 6 form a triangle 6f (e.g., an equilateral triangle).

[0108] That is, the flexible tube 5 of this example has a configuration in which a triangle 6f is used instead of the rounded triangle 6e of the fifth example of the related art shown in FIG.

[0109] The triangle 6f has, for example, a first side along the circumferential direction and a second side and a third side intersecting in the axial direction (and the circumferential direction). When the triangle 6f is, for example, an equilateral triangle, the second side and the third side intersect with the axial direction at angles of 30° and −30°.

[0110] The concave surface 7 includes a first portion 7f1 along the first side (in Figure 10, one first portion 7f1 is shown surrounded by a dotted line), a second portion 7f2 along the second side (in Figure 10, one second portion 7f2 is shown surrounded by a dashed line), and a third portion 7f3 along the third side (in Figure 10, one third portion 7f3 is shown surrounded by a dashed line).

[0111] The first portion 7f1 is formed discontinuously in the circumferential direction. Therefore, the circumferential length of the first portion 7f1 is shorter than the circumferential length of the outer circumferential surface 5A of the flexible tube 5. The second portion 7f2 and the third portion 7f3 are formed discontinuously in the axial and circumferential directions. Therefore, the axial lengths of the second portion 7f2 and the third portion 7f3 are shorter than the axial length of the entire flexible tube 5. Furthermore, the angular range in the circumferential direction of the second portion 7f2 and the third portion 7f3 is smaller than 360°.

[0112] In this case, the depths of the first portion 7f1, the second portion 7f2, and the third portion 7f3 relative to the convex surface 6 may be different from each other. The lengths of the first portion 7f1, the second portion 7f2, and the third portion 7f3 may also be different from each other. Furthermore, the widths of the first portion 7f1, the second portion 7f2, and the third portion 7f3 may also be different from each other.

[0113] According to the sixth example of the related art, substantially the same effects as those of the first to fifth examples of the related art are achieved.

[0114] According to the sixth example of the related art, the first portion 7f1, the second portion 7f2, and the third portion 7f3 are provided in different directions, and therefore, by adjusting the depth, length, width, and the like of the first portion 7f1, the second portion 7f2, and the third portion 7f3, the degree of freedom in controlling the characteristics can be increased.

[0115] 11 is a diagram showing the configuration of the outer circumferential surface 5A of a flexible tube 5 according to a seventh example of the related art when it is developed into a plane. In the seventh example of the related art, parts that are the same as those in the first to sixth examples of the related art are given the same reference numerals, and descriptions thereof will be omitted as appropriate. In the seventh example of the related art, differences from the first to sixth examples of the related art will be mainly described.

[0116] 11, each of the plurality of convex surfaces 6 forms a polygon when the outer circumferential surface 5A of the flexible tube 5 is developed into a plane. In the example shown in FIG. 10, the convex surfaces 6 form a hexagon 6g (e.g., a regular hexagon).

[0117] 11 is arranged such that a first pair of opposing sides of three pairs of opposing sides are parallel to the axial direction. If the hexagon 6g is a regular hexagon, the second pair of sides and the third pair of sides intersect with the axial direction at 60° and −60°, respectively.

[0118] The concave surfaces 7 are provided between the hexagons 6g. In this case, the concave surfaces 7 along the first pair of sides, the concave surfaces 7 along the second pair of sides, and the concave surfaces 7 along the third pair of sides may be different in depth, width, etc. relative to the convex surface 6. Furthermore, by employing hexagons 6g other than regular hexagons, the lengths of the respective concave surfaces 7 may be different.

[0119] According to the seventh example of the related art, substantially the same effects as those of the first to sixth examples of the related art are achieved.

[0120] Furthermore, according to the seventh example of the related art, the depth, length, width, etc. of the concave surface 7 can be adjusted depending on the position where the concave surface 7 is provided, thereby increasing the degree of freedom in controlling the characteristics.

[0121] 12 is a diagram showing the configuration of the outer circumferential surface 5A of a flexible tube 5 according to an eighth example of the related art when it is unfolded onto a plane. In the eighth example of the related art, parts that are the same as those in the first to seventh examples of the related art are given the same reference numerals, and descriptions thereof will be omitted as appropriate. In the eighth example of the related art, differences from the first to seventh examples of the related art will be mainly described.

[0122] In the first to seventh examples of the related art, each of the plurality of convex surfaces 6 has the same shape. In contrast, in this example, two different types of convex surfaces 6 are combined to form a plane tessellation using the convex surfaces 6.

[0123] When the outer peripheral surface 5A of the flexible tube 5 is unfolded into a plane, the multiple convex surfaces 6 have two types of polygons 6h, for example, a quadrangle 6h1 (e.g., a square) and an octagon 6h2 (e.g., a regular octagon).

[0124] If quadrilateral 6h1 is a square and octagon 6h2 is a regular octagon, quadrilateral 6h1 has four sides of equal length, octagon 6h2 has eight sides of equal length, and the length of one side of quadrilateral 6h1 is equal to the length of one side of octagon 6h2.

[0125] In the example shown in FIG. 12, the plurality of convex surfaces 6 are arranged so that, of two pairs of sides of a quadrangle 6h1, a first pair of sides is axial and a second pair of sides is circumferential.

[0126] The concave surface 7 includes a first portion 7h1 provided between the quadrangle 6h1 and the octagon 6h2, and a second portion 7h2 provided between adjacent octagons 6h2.

[0127] The first portion 7h1 and the second portion 7h2 may have different depths, lengths, widths, etc. depending on the position and direction (axial, circumferential, diagonal, etc.) at which they are provided on the flexible tube 5.

[0128] According to the eighth example of the related art, substantially the same effects as those of the first to seventh examples of the related art are achieved.

[0129] Furthermore, according to the eighth example of the related art, the depth, length, width, etc. of the concave surface 7 can be adjusted according to the position and direction in which the concave surface 7 is provided, thereby increasing the degree of freedom in controlling the characteristics.

[0130] 12 shows an example in which the plurality of convex surfaces 6 have two types of shapes, a rectangle 6h1 and an octagon 6h2, but other types of shapes may be combined.Furthermore, the plurality of convex surfaces 6 are not limited to two types, and may have three or more types of shapes.

[0131] 13 is a diagram showing the configuration of the outer circumferential surface 5A of a flexible tube 5 according to a ninth example of the related art when it is developed into a plane. In the ninth example of the related art, parts that are the same as those in the first to eighth examples of the related art are given the same reference numerals, and descriptions thereof will be omitted as appropriate. In the ninth example of the related art, differences from the first to eighth examples of the related art will be mainly described.

[0132] In the first to seventh examples of the related art, one type of convex surface 6 is periodically arranged, and in the eighth example of the related art, two types of convex surfaces 6 are periodically arranged. In contrast, in this example, one type of convex surface is non-periodically arranged, and a plane is filled with the convex surfaces 6.

[0133] The multiple convex surfaces 6 are arranged non-periodically along the outer peripheral surface 5A. The convex surfaces 6 shown in Fig. 13 are concave 13-gons (concave polygons) 6i having four concave interior angles. Note that in Fig. 13, the multiple concave 13-gons 6i are hatched to make them easier to distinguish, but each of the multiple concave 13-gons 6i has the same shape.

[0134] Specifically, the concave 13-gon 6i is also called "Smith's hat" and is described, for example, on the following website:

[0135] A chiral aperiodic monotile [David Smith1, Joseph Samuel Myers2, Craig S. Kaplan3, and Chaim Goodman-Strauss4] arXiv:2305.17743v1 [math.CO] 28 May 2023 [retrieved on 2023-09-07] Retrieved from the Internet: (URL: https: / / arxiv.org / pdf / 2305.17743.pdf)

[0136] Furthermore, the concave surfaces 7 are arranged between adjacent concave triangular shapes 6i.

[0137] 13, the same shape can be arranged non-periodically, but examples are also known in which the same shape can be arranged non-periodically by combining both the front and back surfaces, as described, for example, on the following website. Such a configuration combining both the front and back surfaces may also be applied to the flexible tube 5.

[0138] An aperiodic monotile [David Smith1, Joseph Samuel Myers*2, Craig S. Kaplan3, and Chaim Goodman-Strauss4] arXiv:2303.10798v2 [math.CO] 29 May 2023 [retrieved on 2023-09-07] Retrieved from the Internet: (URL: https: / / arxiv.org / pdf / 2303.10798.pdf)

[0139] Furthermore, an example is known in which two types of shapes, called Penrose tiles, are combined to arrange figures non-periodically, and such a configuration combining multiple types of shapes may be applied to the flexible tube 5.

[0140] According to the ninth example of the related art, substantially the same effects as those of the first to eighth examples of the related art are achieved.

[0141] Furthermore, according to the ninth example of the related art, it is possible to obtain characteristics that are approximately uniform when viewed globally, but non-uniform when viewed locally.

[0142] 14 is a diagram showing the configuration of the outer circumferential surface 5A of a flexible tube 5 according to a tenth example of the related art when it is unfolded onto a plane. In the tenth example of the related art, parts that are the same as those in the first to ninth examples of the related art are given the same reference numerals, and descriptions thereof will be omitted as appropriate. In the tenth example of the related art, differences from the first to ninth examples of the related art will be mainly described.

[0143] In the first to ninth examples of the related art, the two-dimensional shape of the convex surface 6 (and consequently the concave surface 7) was essentially constant regardless of the axial position. In contrast, in this example, the two-dimensional shape of the convex surface 6 (and consequently the concave surface 7) is changed along the axial direction.

[0144] As shown in FIG. 14, the flexible tube 5 is provided with a first area AR1, a second area AR2, and a third area AR3 along the axial direction.

[0145] In addition, Figure 14 also includes a graph showing the surface shape when the outer surface 5A of the flexible tube 5, unfolded on a plane, is cut along four dashed lines (the axial dashed line, the circumferential dashed line in the first area AR1, the circumferential dashed line in the second area AR2, and the circumferential dashed line in the third area AR3).

[0146] The first area AR1 is, for example, an area with relatively low flexibility (i.e., a hard area). Specifically, each of the plurality of convex surfaces 6 arranged in the first area AR1 forms a diamond 6j when the outer circumferential surface 5A of the flexible tube 5 is unfolded onto a plane. A concave surface 7j is provided between adjacent diamonds 6j.

[0147] The second area AR2 is, for example, an area with relatively moderate flexibility (i.e., medium hardness). Specifically, each of the multiple convex surfaces 6 arranged in the second area AR2 forms a diamond 6k when the outer circumferential surface 5A of the flexible tube 5 is unfolded onto a plane. The area of ​​one diamond 6k is, for example, smaller than the area of ​​one diamond 6j.

[0148] A concave surface 7k is provided between adjacent diamonds 6k. The concave surface 7k has a ridge 7k1 in the center. The height of the ridge 7k1 is lower than the height of the diamond 6k. In other words, when viewed from the diamond 6k, which is the convex surface 6, the ridge 7k1 is also part of the concave surface 7k. By providing the ridge 7k1, the concave surface 7k is easy to bend and has high stretchability in the direction perpendicular to the ridge 7k1.

[0149] The ratio of the area of ​​the convex surface 6 to the area of ​​the concave surface 7 for each area is, for example, larger in the first area AR1 than in the second area AR2.

[0150] The third area AR3 is, for example, an area with relatively high flexibility (i.e., softness). Comparing the flexibility of each of the areas AR1 to AR3, the following results are obtained: In the axial and circumferential directions, the number of irregularities per unit length is greater in the second area AR2 than in the first area AR1, and greater in the third area AR3 than in the second area AR2. As a result, the flexibility of the second area AR2 is higher than that of the first area AR1, and the flexibility of the third area AR3 is higher than that of the second area AR2.

[0151] The plurality of convex surfaces 6 arranged in the third area AR3 comprise a first convex surface 6l and an inner rhombus 6m when the outer circumferential surface 5A of the flexible tube 5 is unfolded into a plane.

[0152] The first convex surface 6l is a convex surface formed by connecting multiple ring-shaped diamonds (hereinafter referred to as "external diamonds") in the circumferential direction. The fact that the multiple external diamonds are connected in the circumferential direction can be seen from a graph showing the surface shape when the outer peripheral surface 5A is cut along a dashed line in the circumferential direction in the third area AR3. However, the multiple external diamonds may be isolated from each other without being connected in the circumferential direction.

[0153] The inner rhombus 6m is a convex surface that is arranged inside each of the multiple outer rhombus of the first convex surface 6l, without being connected to the outer rhombus. In this way, it is possible to provide another convex surface 6 inside a certain convex surface 6.

[0154] A concave surface 7l is provided between adjacent first convex surfaces 6l in the axial direction. Also, a concave surface 7m is provided between the outer rhombus and inner rhombus 6m of the first convex surface 6l. Thus, the first convex surface 6l and the inner rhombus 6m are each surrounded by a concave surface 7 (concave surface 7l or concave surface 7m) and are isolated from the other convex surfaces 6.

[0155] Thus, in a first range along the axial direction (e.g., any one of the first area AR1, the second area AR2, and the third area AR3), each of the plurality of convex surfaces 6 has a first shape. Also, in a second range along the axial direction different from the first range (e.g., any other area among the first area AR1, the second area AR2, and the third area AR3), each of the plurality of convex surfaces 6 has a second shape different from the first shape.

[0156] In the above description, the shape patterns of the convex surface 6 and the concave surface 7 are switched for each area, but this is not limited to this. For example, it is also possible to use morphing to configure the shape patterns of the convex surface 6 and the concave surface 7 so that they change smoothly along the axial direction.

[0157] According to the tenth example of the related art, substantially the same effects as those of the first to ninth examples of the related art are achieved.

[0158] According to the tenth example of the related art, the shape patterns of the convex surface 6 and the concave surface 7 are changed in the axial direction. This allows for greater axial control of properties such as axial bendability, resistance to expansion and contraction, and torque resistance, depending on how the shape patterns are changed. Therefore, one flexible tube 5 can be configured to include, for example, an area suitable for the tubular portion 2 c and an area suitable for the bending portion 2 b.

[0159] 15 is a perspective view showing a flexible tube 5 of an eleventh example of the related art. In the eleventh example of the related art, parts that are similar to those in the first to tenth examples of the related art are given the same reference numerals, and descriptions thereof will be omitted as appropriate. In the eleventh example of the related art, differences from the first to tenth examples of the related art will be mainly described.

[0160] The flexible tubes 5 of the first to tenth examples of the related art have a plurality of convex surfaces 6 that are isolated from one another and are each surrounded by a concave surface 7. In contrast, the flexible tube 5 of this example has a plurality of convex surfaces 6 that form a ring shape in the circumferential direction and are connected in the axial direction.

[0161] The flexible tube 5 can be applied to the insertion section 2 including the bending section 2b and the tubular section 2c. Here, for example, if a corrugated tube with a bellows structure is used for the tubular section 2c, it is lightweight and has good flexibility, which can contribute to improving the procedure (good bending properties, reduced fatigue of the operator).

[0162] However, a corrugated tube expands and contracts in the axial direction. For this reason, when a corrugated tube is used for the insertion section 2, for example, when performing a push / pull operation in a lower bowel endoscopy procedure, a discrepancy occurs between the operator's insertion sensation and the actual insertion length, reducing the operability of the procedure. Therefore, the configuration of a flexible tube 5, which has improved resistance to expansion and contraction compared to a corrugated tube, will be described with reference to FIG. 15 .

[0163] 15 includes a plurality of convex surfaces 6p arranged in a ring shape in the circumferential direction. A concave surface 7 is disposed between each pair of adjacent convex surfaces 6p. As described above, the concave surfaces 7 may be filled with a filling material to provide a filling structure portion 9.

[0164] Two adjacent convex surfaces 6p are connected by a connecting convex surface. The two adjacent convex surfaces 6p are relatively difficult to expand and contract at the connecting convex surface portion, and relatively easy to expand and contract at the portion where the connecting convex surface is not provided.

[0165] For example, two adjacent convex surfaces 6p are connected by a plurality of connecting convex surfaces 6q that are inclined with respect to the axial direction (i.e., not parallel to the axial direction). For example, the two connecting convex surfaces 6q are inclined at angles that are symmetrical with respect to the axial direction.

[0166] 15, a plurality of connecting convex surfaces 6q are arranged at intervals in the circumferential direction. Each connecting convex surface 6q is connected to each of the two convex surfaces 6p at a certain angle.

[0167] 15, the two connecting convex surfaces 6q are not positioned 180° apart in the circumferential direction. By arranging the connecting convex surfaces 6q at uneven positions around the central axis O, it is possible to control the directions in which the wheel is easy to turn and the directions in which it is difficult to turn.

[0168] In the second example shown in Fig. 15, two adjacent convex surfaces 6p are connected by, for example, an X-shaped connecting convex surface 6x. The connecting convex surface 6x is formed by a plurality of (two in the illustrated example) convex surfaces 6 arranged to intersect with each other. Note that the position at which the plurality of convex surfaces 6 intersect is not limited to the center position of the connecting convex surface 6x (the central position in the axial direction of the connecting convex surface 6x). In this case as well, the connecting convex surface 6x is connected to each of the two convex surfaces 6p at a certain angle.

[0169] Furthermore, in a third example shown in Figure 15, two adjacent convex surfaces 6p are connected, for example, by a Y-shaped connecting convex surface 6y. The connecting convex surface 6y is formed by multiple convex surfaces 6 joining together along the way to form a single convex surface. Note that the position where the multiple convex surfaces 6 join together is not limited to the center position of the connecting convex surface 6y. In this case, the two branched portions of the connecting convex surface 6y are connected at a certain angle to one of the convex surfaces 6p. Furthermore, the joined portion of the connecting convex surface 6y is connected to the other convex surface 6p, for example, perpendicularly.

[0170] Although FIG. 15 shows an example in which three types of connecting convex surfaces 6q, 6x, and 6y are provided, it is of course possible to provide only one or two types.

[0171] According to the eleventh example of the related art, by providing connecting convex surfaces 6q, 6x, and 6y, the property of the corrugated tube expanding and contracting in the axial direction can be suppressed, and a flexible tube 5 can be constructed that is suitable for the curved portion 2b and the tubular portion 2c, which require resistance to expansion and contraction.

[0172] Furthermore, the connecting convex surfaces 6q, 6x, and 6y have portions that are inclined with respect to the axial direction, thereby providing resistance to expansion and contraction when a rotational torque about the central axis O is applied to the flexible tube 5 and torque resistance. In this case, the balance between the expansion and contraction resistance and torque resistance of the flexible tube 5 can be adjusted by adjusting the angle of inclination.

[0173] Furthermore, by adjusting the circumferential positions of the connecting convex surfaces 6q, 6x, and 6y, it is possible to control the directions in which the flexible tube 5 bends easily and the directions in which it is difficult to bend. On the other hand, by arranging the connecting convex surfaces evenly in the circumferential positions, it is possible to equalize the directions in which the flexible tube 5 bends easily.

[0174] Furthermore, by varying the circumferential positions of the connecting convex surfaces 6q, 6x, and 6y that are different in the axial position, the ease of expansion and contraction can be made uniform.

[0175] Furthermore, because the X-shaped connecting convex surface 6x and the Y-shaped connecting convex surface 6y have branched portions, when stress is applied to the flexible tube 5, the stress acts separately. As a result, the stress acting on the flexible tube 5 is alleviated, and expansion and contraction of the flexible tube 5 can be suppressed.

[0176] 16 is a perspective view showing a flexible tube 5 of a twelfth example of the related art. In the twelfth example of the related art, parts that are similar to those in the first to eleventh examples of the related art are given the same reference numerals, and descriptions thereof will be omitted as appropriate. In the twelfth example of the related art, differences from the first to eleventh examples of the related art will be mainly described.

[0177] The flexible tube 5 of this example has a plurality of ring-shaped convex surfaces 6 arranged in the circumferential direction, inclined at alternately different angles relative to the circumferential direction, and connected at adjacent portions.

[0178] The flexible tube 5 includes a first ring-shaped convex surface 6p1 inclined at a first angle relative to the circumferential direction and a second ring-shaped convex surface 6p2 inclined at a second angle relative to the circumferential direction. The first convex surface 6p1 and the second convex surface 6p2 are connected by a connecting portion 6r. The connecting portion 6r is a convex surface where the first convex surface 6p1 and the second convex surface 6p2 intersect.

[0179] That is, when a certain first convex surface 6p1 is focused on, the certain first convex surface 6p1 is connected to the second convex surface 6p2 on one axial side by a first connecting portion 6r, and is connected to the second convex surface 6p2 on the other axial side by a second connecting portion 6r. The first connecting portion 6r and the second connecting portion 6r are, for example, located on opposite sides in the circumferential direction, i.e., at positions that are 180° apart in the circumferential direction.

[0180] For example, if the circumferential angle at which the first connecting portion 6r is provided is 0° and the circumferential angle at which the second connecting portion 6r is provided is 180°, then no connecting portion 6r exists between 0° and 180° and between 180° and 0°.

[0181] Here, an example is shown in which the connecting portions 6r are provided at positions that are 180° apart in the circumferential direction, but by adjusting the circumferential angle at which the connecting portions 6r are provided, the directions that are easy to bend and the directions that are difficult to bend can be controlled.

[0182] In this way, the first convex surface 6p1 is connected to each of the two axially adjacent second convex surfaces 6p2 at two locations, one on each side.Furthermore, the second convex surface 6p2 is connected to each of the two axially adjacent first convex surfaces 6p1 at two locations, one on each side.

[0183] A concave surface 7 is provided between the first convex surface 6p1 and the second convex surface 6p2, except for the connecting portion 6r. Note that, as described above, the concave surface 7 may be filled with a filling material to provide a filled structure portion 9.

[0184] The twelfth example of the related art provides substantially the same effects as the above-described eleventh example of the related art. In addition, by adjusting the inclination angles of the first convex surface 6p1 and the second convex surface 6p2, the balance between the expansion and contraction resistance and the torque resistance of the flexible tube 5 can be adjusted.

[0185] 17 is a perspective view showing a flexible tube 5 of a thirteenth example of the related art. In the thirteenth example of the related art, parts that are similar to those in the first to twelfth examples of the related art are given the same reference numerals, and descriptions thereof will be omitted as appropriate. In the thirteenth example of the related art, differences from the first to twelfth examples of the related art will be mainly described.

[0186] The flexible tube 5 of this example has two convex surfaces 6 that form a ring shape in the circumferential direction and are connected at multiple points in the circumferential direction.

[0187] The flexible tube 5 has a plurality of ring-shaped convex surfaces 6p in the circumferential direction.

[0188] When a certain convex surface 6p is considered, the certain convex surface 6p is connected to the convex surface 6p on one side in the axial direction by a first connecting portion 6s, and is connected to the convex surface 6p on the other side in the axial direction by a second connecting portion 6t. The first connecting portion 6s and the second connecting portion 6t are both convex surfaces 6.

[0189] The first connecting portions 6s are provided at two locations 180° apart in the circumferential direction, for example. The second connecting portions 6t are provided at two locations 180° apart in the circumferential direction, for example. The first connecting portions 6s and the second connecting portions 6t are spaced apart by an angle of, for example, 90° around the central axis O.

[0190] As a result, a certain convex surface 6p is connected to the convex surface 6p on one side in the axial direction by two first connecting portions 6s, and is connected to the convex surface 6p on the other side in the axial direction by two second connecting portions 6t. The first connecting portions 6s and the second connecting portions 6t may be provided at an angle to the axial direction or may be provided parallel to the axial direction.

[0191] Here, a certain convex surface 6p may have a wavy slope along the circumferential direction so as to be close to the convex surface 6p on one side at two first connecting portions 6s and close to the convex surface 6p on the other side at two second connecting portions 6t.

[0192] A concave surface 7 is provided between the plurality of convex surfaces 6p, except for the connecting portions 6s and 6t. Note that, as described above, the concave surface 7 may be filled with a filling material to provide a filling structure portion 9.

[0193] According to the thirteenth example of the related art, substantially the same effects as those of the twelfth example of the related art described above are achieved.

[0194] 16 of the twelfth example of the related art shows an example in which a certain convex surface 6p is connected to other convex surfaces 6p at one location each on the top and bottom (two locations in total). Also, FIG. 17 of the thirteenth example of the related art shows an example in which a certain convex surface 6p is connected to other convex surfaces 6p at two locations each on the top and bottom (four locations in total). The present invention is not limited to these examples, and a configuration in which a certain convex surface 6p is connected to other convex surfaces 6p at three or more locations in total may also be employed.

[0195] 18 to 22 show a first embodiment of the present invention. Fig. 18 is a cross-sectional view showing an example of the configuration of the bending wire 23 in the bending portion 2b of the first embodiment. Fig. 19 is a partial perspective view showing an example of the configuration of the bending wire 23 in the bending portion 2b of the first embodiment.

[0196] 18 and subsequent figures, the proximal direction of the entire endoscope 1 (toward the operation unit 3) is indicated by arrow P, and the distal direction (toward the distal end portion 2a) is indicated by arrow D.

[0197] 18 and subsequent figures, the curved portion designated by reference numeral 2b and the tubular portion designated by reference numeral 2c are shown without exterior members such as braids and outer skins in order to clearly show their internal configurations. In reality, the curved portion 2b and the tubular portion 2c are configured such that their outer surfaces are covered with braids and outer skins.

[0198] Furthermore, in addition to the bending wire 23 inserted into the coil pipe 25, internal components such as air and water supply pipes and treatment tool insertion channels are inserted and arranged inside the bending portion 2b and the tubular portion 2c, but these internal components are not directly related to the present invention and are therefore not shown in the drawings.

[0199] In the first embodiment, parts that are the same as those in the examples of the related art described above will be denoted by the same reference numerals, and descriptions thereof will be omitted as appropriate. In the first embodiment, differences from the examples of the related art will be mainly described.

[0200] The bending portion 2b (first tube) is formed along an axis (central axis O: see FIG. 21 ) extending from the base end direction P side (first side) to the distal end direction D side (second side). The bending portion 2b is configured to be bent by pulling the bending wire 23 (wire).

[0201] That is, the bending wire 23 is inserted from the bending portion 2 b to the tubular portion 2 c, and the proximal direction P side (first side) of the bending wire 23 is connected to a drum or the like in the operation unit 3. The drum in the operation unit 3 rotates in conjunction with the bending operation knob 3 b.

[0202] When the bending operation knob 3b of the operation unit 3 is operated, bending wires 23 arranged inside the insertion unit 2 are pulled from the operation unit 3, bending the bending portion 2b. Note that, for example, four bending wires 23 are provided in an endoscope having a bending portion 2b that can be bent in four directions, up and down and left and right, and, for example, two bending wires 23 are provided in an endoscope having a bending portion 2b that can be bent in two directions, up and down. The following description will mainly take as an example an endoscope 1 that can be bent in four directions.

[0203] The bending portion 2b (first tube) includes a plurality of bending pieces 21 (a plurality of tubes) and a connection mechanism 21b such as a hinge. The bending pieces 21 constituting the bending portion 2b are formed of, for example, metal. The bending pieces 21 are arranged along a central axis O (axis).

[0204] The connection mechanism 21b connects two adjacent bending pieces 21 among the plurality of bending pieces 21 so that one bending piece 21 (cylinder) can be deflected relative to the other bending piece 21 (cylinder). In this way, the plurality of bending pieces 21 are connected by the connection mechanism 21b so as to be swingable.

[0205] 18, 21, etc. show examples of a bending portion 2b that can be bent in four directions, i.e., up, down, left, and right, and is provided with a connection mechanism 21b for bending in the up and down direction and a connection mechanism 21b for bending in the left and right direction.

[0206] The tip (second end) of the bending wire 23 is fixed to the tip side of the bending portion 2b, for example, by a fixing portion 24f to the bending piece 21a located at the tip end (see Figure 21, etc.).

[0207] Within the bending portion 2b, wire receivers 22 are fixed to some of the bending blocks 21. The wire receivers 22 are arranged at appropriate intervals along the axial direction of the bending portion 2b. The wire receivers 22 are, for example, ring-shaped (see FIG. 19), and a bending wire 23 is inserted therethrough.

[0208] The bending mechanism 20 includes a bending portion 2b (first tube), a tube 24 (first guide) (described below), a wire receiver 22 (second guide), and a bending wire 23 (wire). The tube 24 is formed to be softer than the wire receiver 22, for example.

[0209] As described above, the base end side of the bending wire 23 is disposed inside the operation unit 3. Therefore, at least a portion of the bending mechanism 20 (a portion excluding the operation unit 3 and the portion of the bending wire 23 disposed on the first side (proximal end direction P side) of the insertion unit 2) is provided on the second side (distal end direction D side) of the insertion unit 2.

[0210] The connection mechanism 21b is formed separately from the tube 24 (first guide). Therefore, the connection mechanism 21b and the tube 24 may be formed from different materials.

[0211] Fig. 20 is a diagram showing the relationship between the bending wire 23 inserted into the tube 24 and the wire receiver 22 in the first embodiment, in comparison with the relationship between the conventional bending wire 23 and wire receiver 22. In Fig. 20, column A shows the configuration of this embodiment, and column B shows the conventional configuration.

[0212] As shown in Fig. 20 , the bending wire 23 is made of, for example, a twisted wire and has an uneven surface. To reduce the possibility of the uneven surface of the bending wire 23 getting caught, the wire receiver 22 has rounded corners 22r as shown in column B of Fig. 20 .

[0213] Incidentally, there is a type of bending portion 2b whose maximum bending angle exceeds 180°. In such a type, when the insertion portion 2 of the endoscope 1 is inserted into the subject, the bending portion 2b of the insertion portion 2 may assume a complex shape such as a loop shape.

[0214] When the bending operation is performed and the bending wire 23 is pulled while the bending portion 2b has a complex shape, even if the corners 22r of the wire holder 22 are rounded, friction and snagging will occur between the unevenness on the surface of the bending wire 23 and the inner surface and corners 22r of the wire holder 22, increasing the sliding resistance.

[0215] As a result, the traction force of the bending wire 23 is lost in the wire receiver 22, and the amount of operating force required to operate the bending operation knob 3b increases in accordance with the sliding resistance, resulting in a decrease in operability. In addition, the corners 22r of the wire receiver 22 may become worn or chipped.

[0216] 18, 19, and column A in Fig. 20, the bending wire 23 in the first embodiment is inserted into the tube 24 and then inserted into the wire receiver 22. The tube 24 is a first guide that holds the bending wire 23. The wire receiver 22 is a second guide that holds the tube 24.

[0217] The tube 24 is formed into a cylindrical shape using a resin such as HDPE (High-Density Polyethylene) or PTFE (Polytetrafluoroethylene) to provide a smooth surface and wrinkle resistance. Furthermore, the tube 24 has a wall thickness that prevents wrinkles from forming on the inner periphery when bent. The coefficient of friction between the bending wire 23 and the tube 24 is smaller than the coefficient of friction between the bending wire 23 and the wire receiver 22.

[0218] FIG. 21 is a cross-sectional view showing the configuration of the tube 24 through which the bending wire 23 is inserted in the bending portion 2b in the straight state in the first embodiment.

[0219] The tube 24 is provided in the bending portion 2b along the central axis O shown in Fig. 21. The tip of the tube 24 is fixed to the bending link 21a at a fixing portion 24f together with the tip of the bending wire 23. On the other hand, the base end of the tube 24 is not fixed. Therefore, with respect to movement in the axial direction (direction of the central axis O), the tip of the tube 24 is a fixed end and the base end is a free end.

[0220] FIG. 22 is a cross-sectional view showing the state of the tube 24 through which the bending wire 23 is inserted in the bending portion 2b in the maximum bending state in the first embodiment.

[0221] A tubular portion 2c (second tube) is provided on the proximal side (proximal direction P side) of the bending portion 2b along the central axis O. A coil pipe 25 is arranged in the tubular portion 2c along the central axis O. The coil pipe 25 is a third guide that is arranged in the tubular portion 2c along the central axis O. The coil pipe 25 is fixed to a joining component (not shown) that joins the bending portion 2b and the tubular portion 2c.

[0222] Tube 24, whose distal end is fixed by fixing portion 24f, is passed through multiple wire receivers 22 and then through the wire receiver 22 closest to the proximal end, and when it reaches tubular portion 2c, it is positioned so that it is inserted partway into coil pipe 25. Figure 21 shows that tube 24 is arranged so that when bending portion 2b is in the straight state, the length of tube 24 inserted into coil pipe 25 is a first predetermined length D3.

[0223] When the bending wire 23 is pulled, the distal end, which is the fixed end, does not move in the axial direction, but the proximal end, which is the free end, of the tube 24 moves in the axial direction. For example, the proximal end of the tube 24, which is on the outer periphery when bent, moves toward the distal end (toward the distal direction D), and the proximal end of the tube 24, which is on the inner periphery when bent, moves toward the proximal end (toward the proximal direction P).

[0224] Figure 22 shows that when the bending portion 2b is in the maximum bent state, the length of the tube 24 that is extended most to the tip side and that extends into the coil pipe 25 is the second predetermined length D2.

[0225] In a specific product, the second predetermined length D2 may be set to, for example, 1 mm or more and 20 mm or less. Also, the second predetermined length D2 may be set to, for example, 10 mm or more. However, the second predetermined length D2 is not limited to these values.

[0226] The first predetermined length D3 is set to a length (a length that ensures the second predetermined length D2) that prevents the base end of the tube 24 (which applies to all tubes 24, but particularly to the tube 24 that is on the outer periphery when bent) from coming off (pulling out) from the tip of the coil pipe 25 even when the bending portion 2b is bent to the maximum.

[0227] Here, consider a case where four bending wires 23 are provided for bending R (right), L (left), U (upper), and D (lower).

[0228] When the bending wire 23 for R (right) bending is pulled to the maximum, the bending portion 2b is bent to the maximum in the R (right) direction, and at this time, the tube 24 through which the bending wire 23 for L (left) bending is inserted is extended to the maximum extent toward the tip side.

[0229] When the bending wire 23 for L (left) bending is pulled to the maximum, the bending portion 2b is bent to the maximum in the L (left) direction, and at this time, the tube 24 through which the bending wire 23 for R (right) bending is inserted is extended to the maximum extent toward the tip side.

[0230] When the bending wire 23 for U (upward) bending is pulled to the maximum, the bending portion 2b is bent to the maximum in the U (upward) direction, and at this time, the tube 24 through which the bending wire 23 for D (downward) bending is inserted extends to the maximum extent toward the tip side.

[0231] When the bending wire 23 for D (downward) bending is pulled to the maximum, the bending portion 2b is bent to the maximum in the D (downward) direction, and at this time, the tube 24 through which the bending wire 23 for U (upward) bending is inserted extends to the maximum extent toward the tip side.

[0232] The first predetermined length D3 is set based on the radial length R (see Figure 21) from the central axis O of the bending portion 2b to the center of the wire holder 22, the length L (see Figure 21) of the bending portion 2b in the direction of the central axis O, and the bending angle θmax (see Figure 22) when the bending portion 2b is bent to the maximum.

[0233] The bending angle θmax when the bending portion 2b is bent to the maximum may differ depending on whether the bending direction is R (right), L (left), U (up), or D (down). Therefore, even if the second predetermined lengths D2 for R (right), L (left), U (up), or D (down) at the maximum bending are set to the same, the first predetermined length D3 may differ depending on whether the bending wire 23 for bending is R (right), L (left), U (up), or D (down) and the tube 24 is inserted therein.

[0234] According to the first embodiment, the bending mechanism 20 is configured by inserting the bending wire 23 into the tube 24 having a smooth surface, and then inserting the tube 24 with the bending wire 23 inserted into the wire receiver 22. Therefore, the bending wire 23 does not come into direct contact with the wire receiver 22, and no friction or snagging occurs between the irregularities on the surface of the bending wire 23 and the inner circumferential surface or corners 22r of the wire receiver 22.

[0235] The coefficient of friction between the bending wire 23 and the tube 24 is smaller than the coefficient of friction between the bending wire 23 and the wire receiver 22. This reduces the loss of traction force of the bending wire 23 due to the wire receiver 22. In addition, wear and abrasion occurring at the corners 22r of the wire receiver 22 can be reduced.

[0236] Furthermore, the sliding resistance of the bending wire 23 can be reduced without using a powder lubricant. Because no powder lubricant is used, the endoscope 1 can be manufactured in a controlled area such as a clean room. This increases manufacturing flexibility, reduces manufacturing costs, and simplifies the construction of an assembly line.

[0237] Furthermore, because no powder lubricant is used, the configuration of this embodiment can be applied even to single-use endoscopes that are not watertight sealed. This makes it possible to omit the design of watertight seals for parts of the endoscope 1, allowing for more inexpensive endoscope designs.

[0238] It is also possible to reduce the loss of traction force due to friction by applying a resin coating to the surface of the bending wire 23, which is made up of twisted wires. However, even if a resin coating is applied, it is difficult to completely smooth the surface shape of the bending wire 23. In contrast, according to this embodiment, a tube 24 with a completely smooth surface shape can be used. Therefore, the sliding resistance generated between the tube 24 of this embodiment and the wire receiver 22 is smaller than the sliding resistance generated between the bending wire 23 and the wire receiver 22, which are resin-coated.

[0239] In this way, it is possible to provide an inexpensive bending mechanism 20 that can be easily bent with a small amount of operating force, and an endoscope 1 that includes the bending mechanism 20.

[0240] According to the first embodiment, even when the bending portion 2b is bent to the maximum extent, the tube 24 does not come off the coil pipe 25, and interference between the tip end of the coil pipe 25 and the base end of the tube 24 can be prevented. In addition, the base end of the tube 24 can be prevented from getting caught on the inner diameter wall surface of the coil pipe 25.

[0241] Furthermore, the tube 24 is only disposed at the distal end of the tubular portion 2 c, and is not disposed over the entire length of the tubular portion 2 c. Therefore, when the tubular portion 2 c bends and changes shape, the amount of movement of the proximal end of the tube 24, which is the free end, toward the central axis O can be reduced.

[0242] Generally, the total length of the tubular portion 2c is close to the total length of the insertion section 2, and the total length of the bending section 2b is significantly shorter than the total length of the tubular portion 2c. Therefore, in the configuration of this embodiment, the total length of the tube 24 is significantly shorter than the total length of the insertion section 2. Therefore, compared to a configuration in which the tube 24 is provided all the way to the operation section 3 side (see the sixth embodiment described later), it is possible to reduce the sliding resistance between the bending wire 23 and the tube 24, and also to reduce the sliding resistance between the tube 24 and the coil pipe 25.

[0243] 23 to 25 show a second embodiment of the present invention. Fig. 23 is a cross-sectional view showing the configuration of the tube 24 through which the bending wire 23 is inserted in the bending portion 2b in the straight state in the second embodiment. Fig. 24 is a cross-sectional view showing the state of the tube 24 through which the bending wire 23 is inserted in the bending portion 2b in the maximally bent state in the second embodiment.

[0244] In the second embodiment, parts that are the same as those in the first embodiment and the related art described above are denoted by the same reference numerals, and descriptions thereof will be omitted as appropriate. In the second embodiment, differences from the first embodiment and the related art will be mainly described.

[0245] The distal end (second end) of the bending wire 23 is fixed to the distal end side of the bending section 2b, for example, to the bending piece 21a arranged at the distal end by a fixing portion 24h. Unlike the fixing portion 24f of the first embodiment, the fixing portion 24h fixes only the distal end of the bending wire 23, and does not fix the tube 24.

[0246] Similar to the first embodiment, a plurality of wire receivers 22 (second guides) are provided on the plurality of bending pieces 21a.

[0247] The tube 24 (first guide) of this embodiment includes a plurality of partial tubes 24s arranged intermittently along the central axis O. The number of partial tubes 24s associated with a given bending direction is the same as the number of wire receivers 22 associated with the same bending direction. Hereinafter, the number of partial tubes 24s will be represented by a natural number n.

[0248] The n wire receivers 22 fix the n partial tubes 24s at the n fixing portions 24t, respectively. That is, the number of fixing portions 24t associated with a certain bending direction is the same as the number of partial tubes 24s and the number of wire receivers 22 associated with the same bending direction.

[0249] The wire receiver 22 may be fixed to each of the plurality of bending pieces 21 arranged along the central axis O (axis). The wire receiver 22 may also be fixed at appropriate intervals to the plurality of bending pieces 21 arranged along the central axis O (axis). To give a specific example, the wire receiver 22 may be fixed only to the even-numbered bending pieces 21 counting from the tip side, or may be fixed to one in every three bending pieces 21, or may be fixed in some other arrangement.

[0250] The sum of the lengths of all the partial tubes 24s arranged on one bending wire 23 in the direction along the central axis O is shorter than the length of the bending wire 23 on the inner side within the bending portion 2b when the bending portion 2b is in the maximum bending state, as shown in Figure 24.

[0251] Furthermore, the lengths and spacing of all the partial tubes 24s arranged on one bending wire 23 are set so that adjacent partial tubes 24s do not interfere with each other (their positions along the central axis O do not overlap each other) when the bending section 2b is in the maximum bending state.

[0252] Furthermore, a sufficient gap is provided between the base end of the partial tube 24s arranged closest to the base end and the tip end of the coil pipe 25. Therefore, regardless of the bending state, the partial tube 24s and the coil pipe 25 do not interfere with each other.

[0253] According to the second embodiment, the sum of the lengths of the n partial tubes 24s provided intermittently for one bending wire 23 is shorter than the length of a tube 24 in which only one wire is arranged. Therefore, the total length of the contact portion of the bending wire 23 with the n partial tubes 24s is also shorter than the contact length of the bending wire 23 with one tube 24. By shortening the contact length, it is possible to reduce the sliding resistance between the bending wire 23 and the n partial tubes 24s. Therefore, it is possible to further reduce the operating force and improve operability.

[0254] Furthermore, the n partial tubes 24s are fixed to the n wire receivers 22 at the n fixing portions 24t, respectively. Therefore, the partial tubes 24s do not move relative to the wire receivers 22 to which they are fixed, meaning that no sliding resistance occurs between the partial tubes 24s and the wire receivers 22.

[0255] FIG. 25 is a cross-sectional view parallel to the central axis O showing a modified example of the partial tube 24s constituting the discontinuous tube 24 in the second embodiment.

[0256] Each partial tube 24s has an insertion hole 24e therein for inserting the bending wire 23. In the second embodiment, a plurality of partial tubes 24s are arranged on one bending wire 23. For this reason, if edges are present at the entrance and exit of the insertion hole 24e, twice the number (2n) of edges (n) of partial tubes 24s arranged on one bending wire 23 can come into contact with the bending wire 23. This total number of edges is n times the number (2) of edges when only one tube 24 is arranged on one bending wire 23.

[0257] Therefore, by providing R-shaped portions 24r at the entrance and exit of the insertion holes 24e of all the partial tubes 24s, the edges are rounded to reduce sliding resistance.

[0258] According to the modified example of the second embodiment, the sliding resistance between the bending wire 23 and the n partial tubes 24s can be further reduced, and the amount of operating force can be further reduced, thereby improving operability.

[0259] The configuration in which the R-shaped portions 24r are provided at the entrance and exit of the insertion hole 24e may be applied to the tube 24 of other embodiments.

[0260] Third Embodiment FIG. 26 is a cross-sectional view perpendicular to the central axis O, showing the configuration of a tube 24 through which a bending wire 23 is inserted in a third embodiment of the present invention.

[0261] In the third embodiment, parts that are the same as those in the first and second embodiments and the related art will be denoted by the same reference numerals, and descriptions thereof will be omitted as appropriate. In the third embodiment, differences from the first and second embodiments and the related art will be mainly described.

[0262] In this embodiment, the tube 24 is flattened to include a minor axis r1 in the radial direction in a cross section perpendicular to the central axis O. The tube 24 also includes a major axis r2 in a radial direction different from the minor axis r1. In Figure 26, the minor axis r1 and the major axis r2 are shown as the minor and major axes, respectively, inside the insertion hole 24e, which has an elliptical cross section.

[0263] In the illustrated example, the cross section of the tube 24 perpendicular to the central axis O is elliptical, but this is not limited to this and any cross-sectional shape may be used as long as the radial length varies.

[0264] As the bending angle increases, the deformation of the tube 24 also increases in accordance with the magnitude of the bending angle. This narrows the gap between the inner wall of the tube 24 and the bending wire 23, and it is thought that the inner wall of the tube 24 and the bending wire 23 come into contact with each other, increasing the sliding resistance.

[0265] In contrast to this, according to the third embodiment, by using the tube 24 with an irregular cross section having the minor axis r1 and the major axis r2, during bending, the bending wire 23 can escape to the major axis r2 side within the tube 24. Therefore, sliding resistance when the bending wire 23 is pulled can be reduced, and deterioration of operability can be suppressed.

[0266] [Fourth Embodiment] Fig. 27 is a diagram showing a configuration example in which wire receivers 22A, 22A0 are integrally provided with a bending piece 21 in a fourth embodiment of the present invention. In Fig. 27, the first column shows an example of the wire receiver 22A according to this embodiment, and the second column shows an example of a general wire receiver 22A0 for comparison with this embodiment. Also, in Fig. 27, column A is a partial side view of the wire receivers 22A, 22A0 viewed from a direction perpendicular to the central axis O, and column B is a partial perspective view of the wire receivers 22A, 22A0 viewed from the front direction along the central axis O.

[0267] In the fourth embodiment, the same parts as those in the first to third embodiments and the related art will be denoted by the same reference numerals, and the description thereof will be omitted as appropriate. In the fourth embodiment, the differences from the first to third embodiments and the related art will be mainly described.

[0268] The wire holder may be provided separately from the bending piece 21 (see Figure 36 described later) or integrally with the bending piece 21 (see Figure 37 described later), and this embodiment corresponds to the case where it is provided integrally.

[0269] In this case, the bending piece 21 constituting the bending portion 2b and the wire receivers 22A and 22A0 are made of the same material.

[0270] The wire holder 22A0 shown in the second column is formed, for example, by making two notches in a part of the circumference of the cylindrical body constituting the curved link 21 and deforming the notched part toward the inner diameter by, for example, press processing.

[0271] Between the wire receiver 22A0 and the cylindrical body constituting the bending piece 21, an insertion hole 22e is formed for inserting the bending wire 23 held by the tube 24.

[0272] The wire receiver 22A shown in the first column is basically formed in the same manner as the wire receiver 22A0. That is, the wire receiver 22A is formed, for example, by making two cuts in a part of the circumference of the cylindrical body constituting the curved link 21 and deforming the cut portion toward the inner diameter side by, for example, press working.

[0273] On the other hand, wire receiver 22A differs from wire receiver 22A0 in that tongue pieces 22a are further formed at the entrance and exit of insertion hole 22e during press working, and rounded corners 22r are formed at positions facing tongue pieces 22a at the entrance and exit of insertion hole 22e.

[0274] According to the fourth embodiment, when the wire receiver 22A is formed by press working, the tongue piece 22a is further formed. Therefore, even when the tube 24 moves back and forth relative to the wire receiver 22A in the direction of the central axis O during bending, the sliding resistance generated can be reduced. Therefore, the amount of operating force required to operate the bending operation knob 3b is reduced, improving operability.

[0275] 28 is a diagram showing the configuration of a tube 24 through which a bending wire 23 is inserted in a fifth embodiment of the present invention. In the fifth embodiment, the tube 24 is disposed only in the bending portion 2b.

[0276] In the fifth embodiment, the same parts as those in the first to fourth embodiments and related art will be denoted by the same reference numerals, and the description thereof will be omitted as appropriate. In the fifth embodiment, the differences from the first to fourth embodiments and related art will be mainly described.

[0277] The distal end of the tube 24 is fixed to the bending piece 21 a at a fixing portion 24 f together with the distal end of the bending wire 23. The tube 24 is passed through a plurality of wire receivers 22, and further passed through the wire receiver 22 on the most proximal end side, before terminating inside the bending portion 2 b.

[0278] The bending wire 23 extending from the tube 24 in the bending portion 2 b is inserted into the coil pipe 25 when it reaches the tubular portion 2 c.

[0279] When the bending wire 23 is pulled, the tube 24 has a fixed distal end that does not move, and a free proximal end that moves in the axial direction. For example, the proximal end of the tube 24, which is on the inner circumferential side when bent, moves toward the proximal end (toward the tubular portion 2c). Even at this time, a predetermined distance D1 is provided between the proximal end (end on the first side (proximal direction P)) of the tube 24 (first guide) and the distal end (end on the second side (distal direction D)) of the coil pipe 25 (third guide) so that the proximal end of the tube 24 does not come into contact with the distal end of the coil pipe 25.

[0280] Furthermore, the base end of the tube 24, which is on the outer periphery when bent, moves toward the tip (toward the tip portion 2a). Even at this time, the length of the tube 24 is adjusted so that the base end of the tube 24 does not fall off the wire receiver 22 on the most proximal side.

[0281] That is, the length of the tube 24 is adjusted taking into consideration both the case where the tube 24 is on the inner circumferential side and the case where the tube 24 is on the outer circumferential side of the curve. Specifically, the length of the tube 24 is adjusted so that when the entire insertion section 2 is in a straight state, the base end of the tube 24 is located approximately midway between the wire receiver 22 on the base end side and the tip end of the coil pipe 25. In this case, the length of the tube 24 is slightly shorter than the overall length of the curved section 2b.

[0282] According to the fifth embodiment, similarly to the above-described embodiments, the sliding resistance can be reduced, the amount of operating force can be suppressed, and operability can be improved. In addition, interference between the base end of the tube 24 and the wire receiver 22 and the coil pipe 25 can be prevented.

[0283] 29 is a diagram showing the configuration of a tube 24 through which a bending wire 23 is inserted in a sixth embodiment of the present invention. In the sixth embodiment, the tube 24 is disposed inside the bending portion 2 b and the tubular portion 2 c.

[0284] In the sixth embodiment, the same parts as those in the first to fifth embodiments and the related art will be denoted by the same reference numerals, and the description thereof will be omitted as appropriate. In the sixth embodiment, the differences from the first to fifth embodiments and the related art will be mainly described.

[0285] The distal end of the tube 24 is fixed to the bending link 21 a at a fixing portion 24 f together with the distal end of the bending wire 23. The tube 24 is inserted through the bending portion 2 b and further inserted through the coil pipe 25 of the tubular portion 2 c. Although not shown, the proximal end of the tube 24 extends from the coil pipe 25 on the proximal end side of the tubular portion 2 c. The proximal end side of the tube 24 is movable into the operation unit 3.

[0286] According to the sixth embodiment, the same effects as those of the fifth embodiment are achieved.

[0287] Furthermore, the coil pipe 25 has a spiral unevenness on the inner surface thereof, so that the bending wire 23 made of a twisted wire may get caught on the unevenness on the inner surface of the coil pipe 25 when pulled, which may increase the sliding resistance.

[0288] In contrast to this, according to the sixth embodiment, the tube 24 is also disposed inside the coil pipe 25, and therefore it is possible to suppress an increase in sliding resistance inside the coil pipe 25 when pulling the bending wire 23. In this way, it is possible to reduce sliding resistance throughout the entire insertion section 2, and it is possible to further reduce the amount of operating force required for the bending operation knob 3b.

[0289] 30 is a diagram showing the configuration of a tube 24 through which a bending wire 23 is inserted in a seventh embodiment of the present invention. In the seventh embodiment, a first tube 24A (first guide) and a second tube 24B (fourth guide) are provided as the tube 24, and the first tube 24A is inserted and disposed in the bending portion 2b, and the second tube 24B is inserted and disposed in the tubular portion 2c.

[0290] In the seventh embodiment, the same parts as those in the first to sixth embodiments and related art will be denoted by the same reference numerals, and the description thereof will be omitted as appropriate. In the seventh embodiment, the differences from the first to sixth embodiments and related art will be mainly described.

[0291] The first tube 24A is configured in the same manner as the tube 24 of the fifth embodiment shown in Fig. 28. That is, the tip of the first tube 24A is fixed to the bending link 21a at a fixing portion 24f together with the tip of the bending wire 23. Furthermore, the length of the first tube 24A is adjusted so that the base end of the first tube 24A is located approximately midway between the wire receiver 22 on the base end side and the tip of the coil pipe 25 when the entire insertion section 2 is in a straight state.

[0292] The second tube 24B (fourth guide) has an end (tip) on the tip direction D side (second side) that is fixed by a second fixing portion 24f′ at the boundary between the bending portion 2b (first tube) and the tubular portion 2c (second tube) together with the tip of the coil pipe 25. Note that the second fixing portion 24f′ does not fix the bending wire 23.

[0293] The second tube 24B is inserted through the coil pipe 25 and can extend from the coil pipe 25 on the proximal end side of the tubular portion 2c, similar to the tube 24 of the sixth embodiment described with reference to Fig. 29. Therefore, the proximal end of the second tube 24B can move into the operation unit 3.

[0294] Similar to the example shown in FIG. 28, a predetermined distance D1 is provided between the base end of the first tube 24A and the second fixed portion 24f' to which the tip of the coil pipe 25 is fixed.

[0295] According to the seventh embodiment, the same effects as those of the sixth embodiment are achieved.

[0296] Furthermore, according to the seventh embodiment, the first tube 24A is disposed within the bending portion 2b, and the second tube 24B is disposed within the tubular portion 2c. Therefore, the influence of the advancement and retraction of the first tube 24A due to the bending of the bending portion 2b can be absorbed within the bending portion 2b, and the influence of the advancement and retraction of the second tube 24B due to the bending of the tubular portion 2c can be absorbed within the tubular portion 2c. Therefore, the length of the advancement and retraction of each of the first tube 24A and the second tube 24B can be reduced compared to the tube 24 in the sixth embodiment.

[0297] This makes it possible to make the sliding resistances generated when the first tube 24A and the second tube 24B come into contact with the internal components of the insertion section 2 smaller than the sliding resistance generated when a single tube 24 comes into contact with the internal components in the sixth embodiment.

[0298] Eighth Embodiment FIG. 31 is a diagram showing the state of the tube 24 when the bending portion 2b is bent in an eighth embodiment of the present invention.

[0299] In the eighth embodiment, the same parts as those in the first to seventh embodiments and related arts described above are denoted by the same reference numerals, and the description thereof will be omitted as appropriate. In the eighth embodiment, the differences from the first to seventh embodiments and related arts will be mainly described.

[0300] When the bending portion 2b is bent, the tube 24 inserted through the wire receiver 22 is bent to match the curved shape of the bending portion 2b. At this time, the tube 24 expands on the outer circumferential side of the bend and contracts on the inner circumferential side.

[0301] As described above, the tube 24 is made of a material that is resistant to wrinkles even when it shrinks, and its wall thickness is set to prevent wrinkles. However, if the curvature radius is small, the amount of shrinkage cannot be absorbed by the elastic deformation of the material alone, and wrinkles may occur on the inner periphery of the curved tube 24. If wrinkles occur in the tube 24, they may get caught on the corners 22r of the wire receiver 22.

[0302] Fig. 32 is a perspective view showing a first configuration example of the tube 24C in the eighth embodiment. Fig. 33 is a diagram showing a cross section and a partially enlarged side view of the tube 24C in the first configuration example in the eighth embodiment. In Fig. 33, column A shows the cross section of the tube 24C, and column B shows the partially enlarged side view of the tube 24C.

[0303] The tube 24C has one or more grooves on its outer surface to prevent wrinkles when it is bent. In the example shown in Figures 32 and 33, one or more grooves 24g1 (multiple in the illustrated example) are provided on the outer surface of the tube 24C, which are parallel to the direction of the central axis of the tube 24C (i.e., form an angle of 0° with the axial direction).

[0304] Here, when the tube 24C is placed in the bending portion 2b, the direction of the central axis of the tube 24C is parallel to the direction of the central axis O. Note that the cross-sectional shape, depth, number, etc. of the grooves 24g1 are not limited to the configurations shown in Figures 32 and 33 .

[0305] Fig. 34 is a perspective view showing a second configuration example of the tube 24D in the eighth embodiment. Fig. 35 is a diagram showing a cross section and a partially enlarged side view of the tube 24D of the second configuration example in the eighth embodiment. In Fig. 35, column A shows the cross section of the tube 24D, and column B shows the partially enlarged side view of the tube 24D.

[0306] The tube 24D has one or more grooves on its outer surface to prevent wrinkles when bent. In the example shown in Figures 34 and 35, the outer surface of the tube 24D has one or more spiral grooves 24g2 (in the illustrated example, multiple grooves) that form an angle δ with respect to the direction of the central axis of the tube 24D. δ is, for example, an angle in the range of 0°<δ≦30°.

[0307] Here, when the tube 24D is placed in the bending portion 2b, the direction of the central axis of the tube 24D is parallel to the direction of the central axis O. Note that the cross-sectional shape, depth, number, etc. of the grooves 24g2 are not limited to the configurations shown in Figures 34 and 35 .

[0308] Combining the configuration examples of both tube 24C and tube 24D, the groove provided on the outer surface (outer peripheral surface) of tube 24 should form an angle of 0° or more and 30° or less (or approximately 30° or less) with respect to the direction of the axis (central axis O).

[0309] According to the eighth embodiment, the grooves 24g1 and 24g2 as shown in FIGS. 32 to 35 are provided on the outer surface of the tube 24, so that the outer surface of the tube 24 is less likely to wrinkle.

[0310] Furthermore, the angle of the grooves 24g1 and 24g2 relative to the direction of the axis (center axis O) is set to be greater than or equal to 0° and less than or equal to 30° (or less than approximately 30°), resulting in a tube 24 that does not impair sliding properties with the wire holder 22.

[0311] Ninth Embodiment FIG. 36 is a partial perspective view showing the configuration of a wire receiver 22B in a bending piece 21 according to a ninth embodiment of the present invention.

[0312] In the ninth embodiment, the same parts as those in the first to eighth embodiments and related arts described above are denoted by the same reference numerals, and the description thereof will be omitted as appropriate. In the ninth embodiment, the differences from the first to eighth embodiments and related arts will be mainly described.

[0313] The bending pieces 21 have hinge mounting holes 21b1 and wire receiving mounting holes 21c. By mounting a hinge to the hinge mounting holes 21b1, two adjacent bending pieces 21 are connected to each other so as to be deflectable.

[0314] A wire receiver 22B, which is formed separately from the cylindrical body constituting the bending link 21, is attached to the wire receiver attachment hole 21c. Inside the wire receiver 22B is an insertion hole 22e for inserting a tube 24 that stores the bending wire 23. In this way, a configuration in which the wire receiver 22B manufactured as a separate part is attached to the bending link 21 may be adopted.

[0315] The bending piece 21 constituting the bending portion 2b and the wire receiver 22B may be made of the same material or different materials.

[0316] According to the ninth embodiment, the wire receiver 22B can be manufactured at low cost with stable quality by using the wire receiver 22B that is a separate part from the main body of the bending piece 21. Therefore, the bending mechanism 20 including the bending piece 21 has a configuration suitable for single-use endoscopes, which require low prices.

[0317] FIG. 37 is a partial perspective view showing the configuration of a wire receiver 22A0 in a bending piece 21 according to a modification of the ninth embodiment.

[0318] As described with reference to the second column of FIG. 27, the wire receiver 22A0 may be formed integrally with the cylindrical body that constitutes the bending piece 21.

[0319] 37, the wire receiver 22A0 is formed by, for example, making two cuts in a part of the circumference of the cylindrical body constituting the bending link 21 and deforming the cut portion toward the inner diameter side by, for example, press working. In this case, the wire receiver 22A0 is made of the same material as the bending link 21.

[0320] Inside the wire receiver 22A0 is an insertion hole 22e for inserting a tube 24 that houses the bending wire 23.

[0321] According to the modification of the ninth embodiment, the wire receiver 22A0 can be formed integrally with the bending piece 21 by press working or the like, which allows for inexpensive production of the bending piece 21. Therefore, the bending mechanism 20 including the bending piece 21 has a configuration suitable for single-use endoscopes, which require low prices.

[0322] [Additional Notes] According to the above description of the embodiment of the present invention, the following configuration can be obtained.

[0323] [Appendix A1] An endoscope includes a flexible tube, the flexible tube being a tube along a central axis extending from one end to the other end, the flexible tube including a plurality of convex surfaces provided on an outer peripheral surface, and a concave surface provided on the outer peripheral surface and defined by the plurality of convex surfaces, the plurality of convex surfaces being isolated from one another by being surrounded by the concave surface on each periphery, and when the concave surface includes a first portion along an axial direction parallel to the central axis, the first portion is formed intermittently in the axial direction, and when the concave surface includes a second portion along a circumferential direction around the central axis, the second portion is formed intermittently in the circumferential direction.

[0324] [Appendix A2] In the endoscope according to Appendix A1, each of the plurality of convex surfaces has the same shape.

[0325] [Appendix A3] In the endoscope according to Appendix A2, each of the plurality of convex surfaces forms a polygon when the outer circumferential surface is developed into a plane.

[0326] [Appendix A4] In the endoscope according to Appendix A2, each of the plurality of convex surfaces forms a rounded polygon when the outer circumferential surface is developed into a plane.

[0327] [Appendix A5] In the endoscope according to Appendix A3, the concave surface has a portion inclined with respect to the axial direction, and the inclined portion forms an angle of 45° or less with the axial direction.

[0328] [Appendix A6] In the endoscope according to Appendix A3, each of the plurality of convex surfaces forms a quadrangle when the outer circumferential surface is developed into a plane.

[0329] [Appendix A7] In the endoscope according to appendix A6, each of the plurality of convex surfaces forms a diamond shape when the outer circumferential surface is developed into a plane.

[0330] [Appendix A8] In the endoscope according to appendix A6, each of the plurality of convex surfaces forms a rectangle when the outer circumferential surface is developed into a plane.

[0331] [Appendix A9] In the endoscope according to Appendix A2, each of the plurality of convex surfaces forms a T-shape when the outer circumferential surface is developed into a plane.

[0332] [Appendix A10] In the endoscope according to Appendix A2, each of the plurality of convex surfaces forms an L-shape when the outer circumferential surface is developed into a plane.

[0333] [Appendix A11] In the endoscope according to Appendix A3, each of the plurality of convex surfaces forms a triangle when the outer circumferential surface is developed into a plane.

[0334] [Appendix A12] In the endoscope described in Appendix A2, the flexible tube comprises: a tube body formed of a material having a first Young's modulus and having the plurality of convex surfaces and the concave surface; and a filling structure portion filled in the concave surface of the tube body and formed of a filling material having a second Young's modulus lower than the first Young's modulus.

[0335] [Appendix A13] In the endoscope according to Appendix A12, the filling structure portion has a filling rate of the filling material that varies along the axial direction.

[0336] [Appendix A14] In the endoscope according to Appendix A2, the radial distances from the concave surface to the plurality of convex surfaces, centered on the central axis, are different from one another.

[0337] [Appendix A15] The endoscope according to Appendix A1, further comprising an insertion section to be inserted into a subject, wherein the flexible tube is provided in the insertion section.

[0338] [Appendix A16] In the endoscope according to Appendix A1, the plurality of convex surfaces are periodically arranged along the outer circumferential surface.

[0339] [Appendix A17] In the endoscope according to Appendix A1, the plurality of convex surfaces are arranged non-periodically along the outer circumferential surface.

[0340] [Appendix A18] In the endoscope according to Appendix A1, the concave surface includes at least one of the first portion and the second portion.

[0341] [Appendix A19] In the endoscope described in Appendix A1, in a first range along the axial direction, each of the plurality of convex surfaces has a first shape, and in a second range along the axial direction that is different from the first range, each of the plurality of convex surfaces has a second shape that is different from the first shape.

[0342] [Appendix A20] An endoscope includes a flexible tube, the flexible tube being a tube along a central axis extending from one end to the other end, the flexible tube including a plurality of convex surfaces provided on an outer peripheral surface, and a concave surface provided on the outer peripheral surface and defined by the plurality of convex surfaces, the plurality of convex surfaces being isolated from one another by being surrounded by the concave surface on each periphery, and all of the concave surfaces being inclined with respect to an axial direction parallel to the central axis and inclined with respect to a circumferential direction around the central axis.

[0343] [Appendix B1] An endoscope comprises a flexible tube, the flexible tube being a tube along a central axis extending from one end to the other end, the flexible tube comprising a plurality of convex surfaces provided on an outer peripheral surface, and a concave surface provided on the outer peripheral surface and defined by the plurality of convex surfaces, the plurality of convex surfaces being isolated from one another by being surrounded by the concave surface on each periphery, and all of the concave surfaces being inclined with respect to an axial direction parallel to the central axis and inclined with respect to a circumferential direction around the central axis.

[0344] [Appendix B2] In the endoscope according to Appendix B1, each of the plurality of convex surfaces forms a quadrangle when the outer circumferential surface is developed into a plane.

[0345] [Appendix B3] In the endoscope according to Appendix B1, each of the plurality of convex surfaces forms a diamond shape when the outer circumferential surface is developed into a plane.

[0346] [Appendix B4] In the endoscope according to Appendix B1, each of the plurality of convex surfaces forms a rectangle when the outer circumferential surface is developed into a plane.

[0347] [Appendix B5] A flexible tube is a tube along a central axis extending from one end to the other end, and comprises a plurality of convex surfaces provided on an outer peripheral surface, and a concave surface provided on the outer peripheral surface and defined by the plurality of convex surfaces, wherein the plurality of convex surfaces are isolated from one another by being surrounded by the concave surface on each periphery, and when the concave surface includes a first portion along an axial direction parallel to the central axis, the first portion is formed intermittently in the axial direction, and when the concave surface includes a second portion along a circumferential direction around the central axis, the second portion is formed intermittently in the circumferential direction.

[0348] It should be noted that the present invention is not limited to the above-described embodiments. In the implementation stage, the components of the present invention can be modified and embodied without departing from the spirit of the invention. Furthermore, various aspects of the invention can be formed by appropriately combining multiple components disclosed in the above embodiments. For example, some components may be omitted from all the components disclosed in the embodiments. Furthermore, components from different embodiments may be appropriately combined. In this way, it goes without saying that various modifications and applications are possible within the spirit of the invention.

[0349] This application claims priority from provisional application No. 63 / 599,292 filed November 15, 2023, the contents of which are incorporated herein by reference in their entirety, including the specification, claims, and drawings.

Claims

1. A bending mechanism comprising: a first tube formed along an axis extending from a first side to a second side and configured to be bent by pulling a wire; a first guide formed in a cylindrical shape from resin, provided on the first tube along the axis, and holding the wire; and a second guide fixed to the first tube and holding the first guide.

2. The bending mechanism according to claim 1, characterized in that the first tube comprises: a plurality of tubes arranged along the axis; and a connection mechanism that connects two adjacent tubes among the plurality of tubes so that one tube can be deflected relative to the other tube, and the connection mechanism is formed separately from the first guide.

3. The bending mechanism according to claim 1, characterized in that the resin is HDPE, i.e., High-Density PolyEthylene, or PTFE, i.e., Polytetrafluoroethylene.

4. The bending mechanism according to claim 1, further comprising: the wire is inserted through the first guide; the second end of the wire is fixed to the second side of the first tube; and the coefficient of friction between the wire and the first guide is smaller than the coefficient of friction between the wire and the second guide.

5. The bending mechanism according to claim 1, characterized in that the first guide has a groove on its outer circumferential surface that forms an angle of 30° or less with respect to the axial direction.

6. The bending mechanism according to claim 1, further comprising: a second tube provided along said axis on the first side of said first tube; and a third guide disposed on said second tube along said axis, wherein said first guide is disposed extending from said first tube to partway into said third guide, and is disposed such that when said first tube is in a straight state, the length of said first guide extending into said third guide is a first predetermined length.

7. The bending mechanism described in claim 6, characterized in that the first specified length is set to a length that prevents the first guide from coming off the third guide even when the first tube is in a maximally bent state, based on the radial length from the central axis of the first tube to the center of the second guide, the axial length of the first tube, and the bending angle when the first tube is maximally bent.

8. The bending mechanism according to claim 6, characterized in that a second predetermined length of the first guide inserted into the third guide when the first tube is in a maximally curved state is set to be 1 mm or more and 20 mm or less.

9. The bending mechanism according to claim 6, characterized in that, when the first tube is in a maximally curved state, a second predetermined length of the first guide inserted into the third guide is set to be 10 mm or more.

10. The bending mechanism according to claim 1, characterized in that the first guide includes a plurality of partial guides arranged intermittently along the axis, and a plurality of the second guides are arranged, and the plurality of second guides fix the plurality of partial guides, respectively.

11. The bending mechanism according to claim 10, characterized in that the first tube comprises: a plurality of cylinders arranged along the axis; and a connection mechanism that connects two adjacent cylinders among the plurality of cylinders so that one cylinder can be deflected relative to the other cylinder; and the plurality of second guides are fixed to the plurality of cylinders, respectively.

12. The bending mechanism according to claim 1, characterized in that the first guide is formed flat so as to include a minor axis in the radial direction in a cross section perpendicular to the axis.

13. The bending mechanism according to claim 1, wherein the first tube and the second guide are formed from the same material.

14. The bending mechanism according to claim 1, further comprising: a second tube provided along the axis on the first side of the first tube; and a third guide disposed on the second tube along the axis, wherein an end of the first guide on the first side is disposed so as to provide a predetermined distance between the end of the third guide on the second side.

15. The bending mechanism according to claim 14, further comprising a fourth guide inserted through the third guide, the second end of which is fixed to the boundary between the first tube and the second tube.

16. The bending mechanism according to claim 1, wherein the first tube is made of metal.

17. The bending mechanism according to claim 1, wherein the first guide is formed to be softer than the second guide.

18. An endoscope comprising: an insertion section configured to be inserted into a subject; an operation section provided on a first side of the insertion section; and a bending mechanism at least a portion of which is provided on a second side of the insertion section, wherein the bending mechanism comprises: a first tube formed along an axis extending from the first side to the second side and configured to be bent by pulling a wire; a first guide formed in a cylindrical shape from resin, provided on the first tube along the axis, and holding the wire; and a second guide fixed to the first tube and holding the first guide, wherein the first side of the wire is connected to the operation section.

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