Bending device

Abstract: A bending device for use in an endoscope, a catheter or the like is of a simple construction having a coil (31), an operating wire (51) and a pair of limitation members (33; 55) for limiting an axial compression of the coil. The pair of limitation members are arranged along the length of the coil, and are mounted respectively on diametrically-opposite portions of the coil. The coil is bendable in a direction perpendicular to a plane in which the pair of limitation members are disposed. Instead of the coil, a bellows (60) can be used.

Description: BACKGROUND OF THE INVENTION This invention relates to a bending device for use, for example, in an endoscope. As is well known, an endoscope comprises a hollow body, a flexible insertion portion extending from a front end of the body, a flexible bending portion extending from a distal end of the insertion portion, and a rigid portion provided at a distal end of the bending portion. An inspection window and an illumination window are formed at the rigid portion. Japanese Utility Model Publication No. 9274/77 discloses a flexible tube structure for an endoscope which structure has one coil and a resilient thin plate. Fig. 1 of Japanese Laid-Open (Kokai) Utility Model Application No. 10605/80 shows an example in which this flexible tube structure is applied to a bending portion of an endoscope. More specifically, in the bending portion, the resilient thin plate is received in an internal space defined by the coil and extends in the longitudinal direction of the coil. Recesses are formed in each of opposite lateral edges of the resilient thin plate, and are juxtaposed in the longitudinal direction of this plate. The turn portions of the coil are engaged in the recesses. The bending portion is bent in a direction perpendicular to the plane of the resilient thin plate by an operating wire, so as to direct an inspection window and an illumination window of the rigid portion toward a desired direction. The above resilient thin plate performs two functions. The first function is to prevent the coil from being axially compressed when pulling the operating wire, thereby ensuring a proper bending of the bending portion. The second function is to limit the direction of bending of the bending portion to a direction perpendicular to the plane of the resilient thin plate. The above bending portion is simple in construction, and can be easily manufactured. However, since the resilient thin plate is received in the internal space of the coil in such a manner that this plate divides the internal space into two space portions, the resilient thin plate is obstructive when optical fiber bundles, guide tubes and etc., are to be inserted into the internal space. As a result, considerable limitations are imposed on the thicknesses or diameters of the optical fiber bundles and the guide tubes. Moreover, a dead space tends to be present in the two space portions, thus failing to make effective use of the internal space. Referring to another prior art, Japanese Laid-Open Utility Model Application No. 110443/77 discloses a fiber scope including a bellows which is not designed to be bent by an operating wire. US-A-3060972 describes a flexible tube structure suitable for endoscopic devices which is made up of a plurality of tube sections arranged in end-to-end relationship, or a plurality of thin plate-like elements similarly arranged. In EP-A-0 397 489 (Art. 54(3) EPC) a device is described which includes a plurality of coils combined together so that turns of the coils alternate with each other. The axes of the coils are maintained in radially spaced-apart relationship by means of resilient support members extending along the coils. SUMMARY OF THE INVENTION It is an object of this invention to provide a bending device which is simple in construction because of the use of a coil, and enables an internal space of the coil to be used effectively. The above object has been achieved by a bending device comprising: (a) a single coil having an internal space therein, and comprising a number of turn portions juxtaposed in a direction of an axis of the coil; (b) operating wire means for bending the coil, the operating wire means having a proximal end portion adapted to receive an operating force, the operating wire means having a distal end portion substantially fixed to a distal end portion of the coil; and (c) at least one pair of limitation members extending in an axial direction of the coil and mounted respectively on diametrically-opposite portions of the coil, said pair of limitation members being independent from each other, the limitation members engaging the turn portions of the coil to keep the turn portions at substantially constant intervals, and the coil being bendable in a direction perpendicular to a plane in which the pair of limitation members are disposed. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view of an endoscope incorporating a bending portion according to the present invention; Fig. 2 is an enlarged, front-elevational view showing an internal structure of the bending portion; Fig. 3 is an enlarged, plan view showing the internal structure of the bending portion: Fig. 4 is a cross-sectional view taken along the line IV-IV of Fig. 2; Fig. 5 is an enlarged, fragmentary view showing a condition of engagement between a coil and a strip; Fig. 6 is a cross-sectional view of portions of the coil and the strip in a bent condition of the bending portion; Figs. 7 and 8 are views similar to Fig. 5, but showing modified bending portions, respectively; and Figs. 9 and 10 are perspective views showing internal structures of further modified bending portions, respectively. DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION A preferred embodiment of the invention will now be described with reference to the drawings. An endoscope shown in Fig. 1 comprises a hollow body 10, an insertion portion 20 extending from a front end of the body 10, a bending portion (bending device) 30 extending from a distal end of the insertion portion 20, and a rigid portion 40 provided at a distal end of the bending portion 30. Each of the insertion portion 20 and the bending portion 30 has a tubular shape, and is so flexible as to be bent. An ocular tube 11 is mounted on the proximal end of the body 10, and a manipulation dial 12 is mounted on the peripheral wall of the body 10, and a forceps inlet portion 13 is formed on the peripheral wall of the body 10. A cable (not shown) is fixedly secured at one end to the peripheral wall of the body 10, and a connector (not shown) to be connected to a light source device is mounted on the other end of this cable. As shown in Fig. 2, the rigid portion 40 comprises a frame 41. The frame 41 has a base portion 41a of a circular cross-section, and a cylindrical portion 41b extending from the base portion 41a toward the bending portion 30. An inspection window, an illumination window, a forceps outlet and etc., are provided at the base portion 41a. The ocular tube 11 is optically connected to the inspection window via an image transmitting system (not shown) including an optical fiber bundle passing through the body 10, the insertion portion 20 and the bending portion 30. With this arrangement, inspection from the ocular tube 11 can be made. Illumination light from the light source device is applied to the illumination window via an optical fiber bundle passing through the above connector, the above cable, the body 10, the insertion portion 20 and the bending portion 30. The forceps outlet is connected to the forceps inlet portion 13 via a guide tube (not shown) passing through the body 10, the insertion portion 20 and the bending portion 30. The insertion portion 20 includes a holder coil (not shown) made from a strip or elongated narrow plate. A proximal end of this holder coil is fixedly secured to the body 10, and the distal end of the holder coil is connected to a connecting tube (not shown). A braid tube (not shown) is fitted on the holder coil, and a tube 22 (shown only in Fig. 1) made of a resin or rubber is fitted on the braid tube. The internal structure of the bending portion 30 will now be described in detail with reference to Figs. 2 to 6. The bending portion 30 includes a coil 31. The coil 31 has a number of turn portions 31a each having a circular or round shape as viewed in the axial direction of the coil 31 as shown in Fig. 4. The turn portion 31a are juxtaposed in the axial direction of the coil 31. The proximal end of the coil 31 is fixedly secured to the above-mentioned connecting tube, and is connected to the distal end of the holder coil of the insertion portion 20 via this connecting tube. The distal end of the coil 31 is fixedly secured to the outer peripheral surface of the cylindrical portion 41b of the frame 41 of the rigid portion 40. The coil 31 has an internal space 32 therein, and the above-mentioned optical fiber bundles and guide tube are received in the internal space 32. A pair of strips or band-like plates (limiting members) 33 are mounted respectively on diametrically-opposite portions (i.e., portions diametrically opposite right and left in Fig. 4) of the outer periphery of the coil 31. Each strip 33 is made of metal, and is relatively thin, and has a narrow width. Each strip 33 extends in the longitudinal direction of the coil 31 over the entire length thereof. As best shown in Fig. 5, the strip 33 is formed or bent into a corrugated shape, and has a number of support portions 33a of a generally semi-circular cross-section spaced at equal intervals from one another along the length of the strip 33. The semi-circular support portion 33a has an inner diameter slightly greater than the transverse cross-section of the turn portion 31a of the coil 31. Each adjacent support portions 33a are interconnected by a connecting portion 33b. The outside section of each turn portion 31a of the coil 31 is received in a respective one of the support portions 33a of each strip 33 over about a half of the cross-section of the turn portion 31a. The support portions 33a of the strip 33 are fixedly secured respectively to the turn portions 31a of the coil 31 by spot welding at regions indicated by reference character A in Fig. 5. With this construction, the turn portions 31a of the coil 31 are arranged at equal intervals in the axial direction of the coil 31. The strip plates 33 may be fixed to the coil 31 by an elastic adhesive or by brazing. A braid tube, softer than the braid tube of the insertion portion 20, is fitted on the outer periphery of the coil 31, and a tube 34 (only shown in Fig. 1), softer than the tube 22 of the insertion portion 20, is fitted on the outer periphery of this braid tube. Next, a mechanism for bending the bending portion 30 will now be described. This mechanism includes two operating wires 51 and 52. The operating wires 51 and 52 are fixedly secured to a peripheral surface of a pulley 50 mounted within the body 10, and extend forwardly from the upper and lower portions of the pulley 50, respectively. The pulley 50 is connected to the manipulation dial 12 via a shaft (not shown) extending through the peripheral wall of the body 10. In the insertion portion 20, the operating wires 51 and 52 are passed respectively through a pair of guide tubes of a small diameter. Each of these guide tubes is formed by spirally winding a wire, and is received within the holder coil. The proximal ends of the guide coils are fixedly secured respectively to diametrically-opposite portions of the body 10 (that is, opposed upper and lower portions of the body 10 in Fig. 1), and the distal ends of the guide coils are fixedly secured respectively to diametrically-opposite upper and lower portions of the inner peripheral surface of the above-mentioned connecting tube. The operating wires 51 and 52 are passed through the internal space 32 of the coil 31, and are fixedly secured at their distal ends respectively to diametrically-opposite upper and lower portions (Figs. 1 and 2) of the cylindrical portion 41b of the frame 41 of the rigid portion 40 by brazing. The positions of fixing of the distal ends of the operating wires 51 and 52, as well as the positions of fixing of the distal ends of the above guide coils, are circumferentially spaced 90° from the pair of strips 33. The connecting portions 33b of the strips 33 have a relatively high rigidity to withstand a compressive force exerted in the longitudinal direction of the coil 31 upon pulling of the operating wire 51 or 52. Therefore, those sections of the turn portions 31a of the coil 31 engaged with each strip 33 are maintained at substantially constant intervals. As a result, the coil 31 and hence the bending portion 30 can not be bent in a direction X indicated in Fig. 4, and can be bent only in a direction Y in Fig. 4 (i.e., upward-downward direction in Fig. 1). In the above construction, when the manipulating dial 12 is angularly moved in a counterclockwise direction (Fig. 1), the operating wire 52 is pulled, and the operating wire 51 is loosened. At this time, since the axial compression of the coil 31 is limited by the strips 33, the pulling force applied by the operating wire 52 is effectively utilized to bend the coil 31 and hence the bending portion 30. More specifically, as shown in Fig. 6, the distance between those sections of the adjacent turn portions 31a engaged with each strip 33 remain unchanged, and the distance between the upper sections of the adjacent turn portions 31a increases whereas the distance between the lower sections of the adjacent turn portions 31a decreases. As a result, the bending portion 30 is bent downward. In contrast, when the manipulating dial 12 is angularly moved in a clockwise direction, the operating wire 51 is pulled, and the operating wire 52 is loosened. As a result, the bending portion 30 is bent upward. During the bending of the bending portion 30, the strips 33 will not affect or obstruct this bending. The reason for this is that because of the corrugated configuration of each strip 33, one lateral edge portion of the strip 33 is resiliently contracted whereas the other lateral edge portion is resiliently expanded, so that the strip 33 is bent in the direction of the width thereof, as shown in Fig. 6. During the bending of the bending portion 30, the turn portions 31a of the coil 31 interfere with one another, thereby maintaining the cross-section of the bending portion 30 in a substantially circular shape. Also, the interference of the turn portions 31a with one another prevents the bending portion 30 from being bent only at one section thereof, thus ensuring a smooth bending. In the above construction, the pair of strips 33 for limiting the coil 31 are independent of each other, and are not received in the internal space 32 of the coil 31. Therefore, the internal space 32 is not divided, and can be effectively used, without any dead space existing therein. As a result, limitations such as a limitation on the thickness of the optical fiber bundles are relaxed as compared with the above-mentioned conventional structure. Other embodiments of the present invention will now be described. Those parts of these other embodiments corresponding respectively to those of the preceding embodiment are designated by identical reference numerals, respectively, and detailed explanation thereof will be omitted. In an embodiment shown in Fig. 7, each adjacent support portions 33a of each strip 33 are disposed in contact with each other, and adjacent turn portions 31a of a coil 31 are spaced from each other a distance twice the thickness of the strip 33. As a result, a pulling force applied by the operating wire is not partially absorbed by a resilient compression of the strips 33 in the axial direction of the coil 31, but is fully used to bend the bending portion. In the embodiment of Fig. 7, connecting portions 33b of the strip 33 are projected considerably radially outwardly from an imaginary cylindrical surface in which the center of the transverse cross-sectional area of each turn portion 31a of the coil 31 lies. With this arrangement, the bending as shown in Fig. 6 is possible. Each of the strips 33 is disposed inside the coil 31, and the support portions 33a mainly support the inside sections of the turn portions 31a of the coil 31. In the embodiment of Fig. 7, the turn portions 31a of the coil 31 are not fixed to the respective support portions 33a of each strip 33. In a natural condition of the strip 33 in which the strip is not subjected to any force, the inner diameter of the support portion 33a is slightly smaller than the diameter of the turn portion 31a, and the support portion 33a is kept engaged with (that is, held in intimate contact with) the turn portion 31a only by the resiliency of the support portion 33a. The support portion 33a circumferentially extends around the transverse cross-section of the turn portion 31a through an angle exceeding 180°. It is preferred that the opposite axial ends of each strip 33 be fixedly secured to the connecting tube at the distal end of the insertion portion and the cylindrical portion of the frame of the rigid portion, respectively. In an embodiment shown in Fig. 8, a pair of wires 55 of metal or a resin are used as limiting members. Each wire 55 cooperates with another wire 56, extending straight in an axial direction of a coil 31, to limit an axial compression of the coil 31. More specifically, the wire 55 is wound on about a half of an outer periphery of each turn portion 31a of the coil 31, and is folded or turned back around the wire 56, and further is wound on about a half of an outer periphery of the adjoining turn portion 31a. In this manner, the wire 55 is engaged with all the turn portions 31a in the axial direction of the coil 31. The distance between each adjacent turn portions 31a of the coil 31 is substantially equal to the diameter of the wire 55. One ends of the wires 55 and 56 are fixedly secured to the connecting tube at the distal end of the insertion portion, and the other ends of these wires are fixedly secured to the cylindrical portion of the frame of the rigid portion. In an embodiment shown in Fig. 9, a coil 31 can be bent in all directions. More specifically, the coil 31 is divided into alternate regions M and N in its axial direction. Each region includes, for example, five turn portions 31a. A pair of strips 33 are connected respectively to diametrically-opposite sections of the turn portions 31a of each region M which sections are spaced from each other in a direction X. Also, a pair of strips 33 are connected respectively to diametrically-opposite sections of the turn portions 31a of each region N which sections are spaced from each other in a direction Y. Four operating wires (not shown) are passed through an internal space of the coil 31. Two of the four operating wires are disposed in diametrically-opposite relation to each other in the direction X with respect to the coil 31 whereas the other two operating wires are disposed in diametrically-opposite relation to each other in the direction Y with respect to the coil 31. When one of the former two operating wires is pulled, the regions N of the coil 31 are bent in the direction X, with the regions M of the coil 31 hardly deformed. When one of the latter two operating wires is pulled, the regions M of the coil 31 are bent in the direction Y, with the regions N of the coil 31 hardly deformed. Thus, the coil 31 can be bent in four directions and hence all directions. An embodiment shown in Fig. 10 is similar to the embodiment of Fig. 9, but differs therefrom on the following points. Namely, a coil 31 has regions L each interposed between adjacent regions M and N, the region L including two turn portions 31a. Two support portions 33a, provided at one end of each of two strips 33 extending from the region M, are engaged respectively with the two turn portions 31a defining the region L. Similarly, two support portions 33a, provided at one end of each of two strips 33 extending from the region N, are engaged respectively with the two turn portions 31a defining the region L. Thus, the two strips 33 extending from the region M and the two strips 33 extending from the region N are engaged with the two turn portions 31a (defining the region L) at four points spaced 90° from one another in the circumferential direction of the coil 31. Thus, the turn portions 31a of the region M and the turn portions 31a of the region N are interconnected via the turn portions 31a of the region L and the strips 33. This arrangement prevents a relative radial displacement between the turn portions 31a of the region M and the turn portions 31a of the region N when any of operating wires 51 to 52 is pulled. The present invention is not to be restricted to the above embodiments, and various modifications can be made. The present invention can be applied to the endoscope of the type in which the thicknesses or diameters of the insertion portion and the bending portion are very small, and further the present invention can be applied to a medical catheter.

Claims: A bending device comprising: (a) a single coil (31) having an internal space (32) therein, and comprising a number of turn portions (31a) juxtaposed in a direction of an axis of said coil (31); and (b) operating wire means (12, 50, 51, 52) for bending said coil (31), said operating wire means (12, 50, 51, 52) having a proximal end portion adapted to receive an operating force, said operating wire means (12, 50, 51, 52) having a distal end portion substantially fixed to a distal end portion of said coil (31); at least one pair of limitation members (33; 55) extending in an axial direction of said coil (31) and mounted respectively on diametrically-opposite portions of said coil (31), said pair of limitation members (33, 55) being independent from each other, said limitation members (33, 55) engaging said turn portions (31a) of said coil (31) to keep said turn portions at substantially constant intervals, and said coil (31) being bendable in a direction perpendicular to a plane in which said pair of limitation (33,55) members are disposed. A bending device according to claim 1, in which said pair of limitation members (33; 55) extend over generally an entire length of said coil (31), and are disposed in a common plane. A bending device according to claim 1, in which said coil (31) has first and second regions (M, N) arranged alternately in the axial direction of said coil, each of said first and second regions comprising a predetermined number of said turn portions (31a), a plurality of pairs of said limitation members (33) being provided, a pair of said limitation members being mounted respectively on diametrically-opposite sections of said turn portions of each of said first regions which sections are spaced from each other in a first direction (X), and a pair of said limitation members being mounted respectively on diametrically-opposite sections of said turn portions of each of said second regions which sections are spaced from each other in a second direction (Y) perpendicular to said first direction. A bending device according to claim 1, in which each of said pair of limitation members comprises a corrugated strip (33), said corrugated strip having a number of support portions (33a) of a generally semi-circular cross-section juxtaposed along a length of said corrugated strip, and connecting portions (33b) each interconnecting respective adjacent ones of said support portions, and said turn portions (31a) of said coil (31) being fitted in and supported by said support portions, respectively. A bending device according to claim 1, in which each of said pair of limitation members comprises a wire (55) which is wound on at least a half of an outer periphery of each of said turn portions (31a) of said coil (31), any adjacent ones of said turn portions being spaced from each other by a distance equal to a diameter of said wire.

Inventors: CHIKAMA TOSHIO, CHIKAMA, TOSHIO
Applicants: MACHIDA ENDOSCOPE CO LTD, KABUSHIKI KAISHA MACHIDA SEISAKUSHO
Application year: 1990
Main classification: A61B1
IPC codes: A61B1, A61M25