Mechanism for bending elongated body

Abstract: A mechanism for bending an elongated body such as the tube of an endoscope without the use of electric elements, thereby eliminating a shock hazard. A shape-momorizing alloy is inserted into the elongated body at portions to be bent. Heat for causing the shape-memorizing alloy and hence the elongated body to bend is produced by frictional heat produced by a mechanism vibrator.

Description: BACKGROUND OF THE INVENTION The present invention relates to a mechanism for bending an elongated body, and more particularly, to a mechanism for bending an elongated body suitable for use in an endoscope or the like. A wide variety of endoscopes have heretofore been available, all of which include bendable elongated body portions, for observing the interior of various organs such as blood vessel, coelomata, and the like. Various mechanisms for bending such an elongated body will be considered. As illustrated in Fig. 1, one well-known mechanism, as disclosed in Japanese Utility Model publication No. 13033/1974, includes a bending tube 62 composed of a multiplicity of nodal rings 61, the central portions of which are formed with fulcrum portions 60 and encasing a segment of fiber 63, and a several of wires 64, first ends of which are fixed to a nodal ring 61 disposed at the tip portion thereof, the wires 64 being inserted through other nodal rings 61. Another well-known bending mechanism, as disclosed in Japanese Laid-Open Patent Publication No. 25140/1983, is composed of a multiplicity of articulated pieces, shape-memorizing alloys provided between the articulated pieces, and a heating device for bending the shape-memorizing alloys in predetermined shapes by heating them with a supplied electric current. Medical devices using shape-memorizing alloys for effecting a displacement is known in the art. For example, EP-A-0 061 783 discloses indirect ultrasonic heating of an actuating element made of a shape-memorizing alloy. Here, the actuating element, in in the form of a coil, is disposed inside a medical capsule which is to be swallowed by the patient. The actuating element should move from one position to another in order to either urge liquid out from the capsule or to enable receipt of liquid as data. The ultrasonic heating means being attached externally to the patient to activate the shape-memorizing alloy. However, regarding the task of bending an elongated body which has directly attached to it a means for heating, in this case only the above-mentioned mechanisms for bending an elongated body which function by manipulating the wires and heating the shape-memorizing alloys by the heating device can be considered. That is, such mechanisms as bending the multiplicity of nodal rings or articulated pieces. Thus, the tip portion of the elongated body can be bent at a predetermined angle, which permits observation of desired portions within a vascular tract or the like. Because, however, the former type of mechanism for bending the elongated body includes a multiplicity of nodal rings and wires required for the bending operation, the structure is complicated. It is therefore difficult to reduce the diameter of the elongated body, resulting in a limitation in the observable diameter of the organ or the like. Consequently, there arises a problem in that ulcers, tumors or the like cannot be detected in their early stages. The amount of bending of the elongated body is adjusted in accordance with the degree to which the wires are moved when observing various organs. Hence, this adjustment leads to problems wherein the operation of bending the elongated body becomes intricate and it is difficult to bend the body at a desired angle with high accuracy. The latter type of bending mechanism is accompanied by problems in addition to those inherent in the former bending mechanism because of the provision of the multiplicity of articulated pieces. To be specific, since the device for heating the shape-memorizing alloy employs an electrically energized heating system, when the elongated body is employed as an endoscope, there may be a danger of electric shock. The practical applications of such an arrangement are restricted. SUMMARY OF THE INVENTION It is a primary object of the present invention, which has been made in light of the above-described problems, to provide a mechanism for bending an elongated body having a simplified structure, which results in a reduced diameter of the elongated body, and with which the elongated body can be accurately bent at a desired angle by a simple operation, and which is also usable for a wide range of applications with no possibility of causing an electric shock. To accomplish the above and other objects, in accordance with the invention, there is provided an improved mechanism for bending an elongated body comprising an exciter, a vibrating member connected to the exciter and slidably contactually disposed in a predetermined portion within the elongated body, and a shape-memorizing alloy disposed in a portion of the elongated body which corresponds to a slide-contacting portion of the vibrating member. In the thus-constructed mechanism for bending an elongated body, the vibrating member is slidably contactually disposed in the predetermined portion within the elongated body. Consequently, when the vibrating member is vibrated by the exciter, the slide-contacting portion increases in temperature due to friction generated between the vibrating member and the elongated body. The heating temperature caused by friction can be controlled by adjusting the exciting intensity of the exciter. The shape-memorizing alloy is disposed in such a portion of the elongated body as to correspond to the slide-contacting portion of the vibrating member so that the shape-memorizing alloy is heated with the frictional heat there generated, thereby bending it in a previously memorized configuration. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic diagram showing a conventional mechanism for bending an elongated body; Fig. 2 is an enlarged schematic sectional view of a principal portion of a mechanism for bending an elongated body used in a fiberscope; Fig. 3 is an end elevation taken substantially along a line XXV-XXV in Fig. 2; Fig. 4 is a sectional view taken substantially along a line XXVI-XXVI in Fig. 2; and Fig. 5 is a schematic diagram illustrating a mechanism for bending the elongated body of Fig. 2. DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will hereinafter be described in detail with reference to the accompanying drawings. Referring to Fig. 2, there is illustrated a schematic enlarged sectional view of a principal portion of a fiberscope which employs a mechanism for bending an elongated body constructed in accordance with the present invention. Fig. 3 is an end elevation taken substantially along as line XXV-XXV in Fig. 2. Fig. 4 is a sectional view taken substantially along a line XXVI-XXVI in Fig. 2. Fig. 5 is a conceptual diagram of a principal portion, illustrating an operational condition of the elongated body shown in Fig. 2. An elongated body 301 is constituted by a detection part D formed at the tip of the elongated body 301 and a bending part B including a bending mechanism provided in continuation from the detection part D. Embedded in the elongated body 301 are light guides 302 for illuminating a portion to be observed, a lens sleeve 303 including objective microlenses 304 disposed at the tip thereof, and a segment of image fiber 305, provided in continuation from the objective microlenses 304, for leading the light emerging from the light guides 302 and reflected from the portion to be observed. These components are combined to constitute the foregoing detection part D. In accordance with the invention, a linear vibrating member 307 connected to an exciter 306 is disposed in sliding contact with a predetermined portion within the elongated body 301. More specifically, the elongated body 301 is formed with a hollow portion 308 leading to the bending part B. The vibrating member 307 is inserted into this hollow portion 308. The vibrating member 307 is slidably contactually disposed in a portion within the hollow portion 308 corresponding to the bending part B. Upon excitation of the exciter 306, the vibrating member 307 vibrates to produce friction with a wall of the hollow portion 308 which corresponds to the bending part B, with the result that the bending part B emits heat because of the thus-produced frictional heat. In this example, the inner wall of the hollow portion 308 excluding the bending part B is smoothly formed of a material having a small frictional resistance to minimize the emission of heat in the portions other than the bending part B. In order to bend the elongated body 301 in a predetermined shape with the aid of the frictional heat, a shape-memorizing alloy 309 having a linear configuration and having a preset transformation temperature is disposed in such a portion within the elongated body 301 as to correspond to the bending part B with which the vibrating member 307 is in sliding contact. For the purpose of enhancing the amount of heat emission due to the friction between the vibrating member 307 and the inner wall of the hollow portion 308 in the bending part B, it is preferable that inner surface of the hollow portion 308 be roughly formed, or a frictional member provided in the hollow portion 308. The elongated body 301 excluding the bending part B, or least the inner wall of the hollow portion 308, is formed of a material having a small frictional resistance. Suitable materials include fluorine-series polymers such as polytetrafluoroethylene and polyhexafluoroproplylene, and silicone resin. Alternatively, the inner surface of the hollow portion 308 can be coated with a fluorine-series oil or silicone series oil, which contributes to a reduction in frictional resistance. The vibrating member 307 may be constructed of linear members formed from various materials, for example, metal. The portion of the vibrating member 307 which corresponds to the bending part B is preferably formed with minute roughness. The bending mechanism having the above-described construction is arranged such that the vibrating member 307 connected to the exciter 306 is slidably contactually disposed in the hollow portion 308 at a position corresponding to the bending part B of the elongated body 301, and the shape-memorizing alloy 309 is provided within the bending part B of the elongated body 301. In this arrangement, when the vibrating member 307 is excited by the exciter 306, the vibrating member 307 vibrates in the hollow portion 308, resulting in the generation of friction with the wall of the hollow portion 308. This friction produces heat with which the shape-memorizing alloy 309 is heated. Therefore, unlike the conventional bending mechanism, there is no necessity to provide the multiplicity of nodal rings and the wires employed for the bending operation, resulting in a simplified structure and in a reduction in the diameter of the elongated body. Thus, it is possible to attain for the elongated body an extremely small outside diameter of 2.0 mm or less. Because the shape-memorizing alloy 309 is heated with frictional heat, no danger of causing an electric shock is presented. Hence, an endoscope employing the invention is very safe. The bending part B may be formed at any desired position along the elongated body 301. It is, however, preferable that the bending part B be provided at the tip of the elongated body 301 to facilitate the observation of the desired organ portion. In the hollow portion at the bending part B, the spacing between the vibrating member 307 and the hollow portion 308 can be variously set depending on the relationship between the excitation intensity of the exciter 306 and the desired heating temperature. In the above-described embodiment, the heating temperature increases in the bending part B. However, heat may be generated throughout the entire hollow portion 308 of the elongated body 301 by forming a partially hollow portion corresponding to the bending part B and the remainder in the same way without roughening the inner surface of the hollow portion 308 corresponding to the bending part B. In this case, the transformation, temperature of the shape-memorizing alloy 309 is set to an allowable value depending upon the application. For instance, where the invention is applied to an endoscope, as in the previous case, the transformation temperature is set to a value slightly higher than in vivo the temperature. As a result, the elongated body 301 can be bent by the bending part B incorporating the shape-memorizing alloy 309 in such a state that the heating temperature in the hollow portion excluding the bending part B is kept low. The shape-memorizing alloy 309 is not confined to linear alloys and may be diversified both in size and in configuration. The shape-memorizing alloy 309 may be any of a wide variety of known material such as a NiTi alloy containing 50 to 60% Ni by weight and 40 to 50% Ti by weight, a NiTi-series alloy, a NiAl alloy, a CuAlNi alloy, a CuSn alloy and a CuZn alloy in which Ni or Ti is partially replaced with elements such as Al, Cu, V, Zr, Cr, Mo, Fe and Co. The shape-memorizing alloy 309 may be exposed to the hollow portion 308 so as to face to the vibrating member 307. The shape-memorizing alloy 309 may previously memorize a configuration having the same or different bending angle or bending degree with respect to a plurality of respective portions in the longitudinal direction. Where a plurality of shape-memorizing alloys which have different transformation angles and memorize the same or different configurations beforehand are provided within the bending part B of the elongated body 301, the heating temperature can be adjusted by varying the exciting intensity of the exciter 306. Hence, the bending portions and the bending configurations of the shape-memorizing alloys can easily be selected. In the above-described embodiment, the elongated body 301 is arranged to be bent in one direction utilizing a single segment of shape-memorizing alloy 309. However, a plurality of vibrating members 307 and a several of shape-memorizing alloys 309 can be provided in the elongated body 301 in the same manner as that described above in order to mutidirectionally bend the elongated body 301. More specifically, for example, when employing four segments of vibrating member 307 and also four segment of shape-memorizing alloy 309, the vibrating member 207 can be disposed within the elongated body 301 in a state where one pair of vibrating members 307 facing each other are arranged orthogonally to another pair of vibrating members 307. The shape-memorizing alloys 309 are provided in the slide-contacting portions of the individual vibrating members 307. By selectively exciting the four segments of vibrating member 307, the elongated body 301 can be selectively bent in four directions. The primary requirement for the exciter 306 of course to cause the vibrating member 307 to vibrate. For this purpose, the exciter 306 may be implemented with an ultrasonic exciter to efficiently excite the vibrating member 307 and to facilitate the control of the heating temperature of the bending part (B). The exciting element of the ultrasonic exciter may be formed by various well-known conventional elements such as a piezoelectric crystal vibrator, an electrostrictive vibrator made of BaTiO₃, a magnetostrictive vibrator, etc. The mechanism for bending the elongated body has a simple structure and is capable of attaining a reduced diameter of the elongated body and guide-bending the desired portions of the elongated body at a predetermined angle or to a predetermined bending degree. As discussed above, in the mechanism for bending an elongated body according to the present invention, a vibrating member is slidably contactually provided in a predetermined portion within the elongated body. Therefore, when the vibrating member is vibrated by the exciter, the temperature of the slide-contacting portion can be increased due to frictional heating. The heating temperature due to such frictional heating can be controlled by adjusting the exciting intensity of the exciter. The shape-memorizing alloy is disposed in a portion within the elongated body corresponding to the slide-contacting portion of the vibrating member. Consequently, the shape-memorizing alloy is heated with frictional heat, and the alloy can thereby be bent in the previously memorized shape. It is therefore possible to reversibly bend and restore the elongated body in predetermined shapes by a simple operation with high accuracy. Because no nodal ring and wire are required, the overall structure is simplified, and the diameter of the elongated body can be reduced. In addition, because the heating of the shape-memorizing alloy involves only the use of frictional heat, there is no danger of electric shock, providing a very safe operation.

Claims: A mechanism for bending an elongated body (301) including a shape-memorizing alloy (309) and heating means for heating said alloy, characterised in that , said heating means comprises: an exciter (306), a vibrating member (307) connected to said exciter and slidably contactually disposed in a predetermined portion within said elongated body (301), and at least one segment of a shape-memorizing alloy (309) disposed in a portion of said elongated body corresponding to a slide-contacting portion of said vibrating member. The mechanism for bending an elongated body as set forth in claim 1, wherein said exciter comprises an ultrasonic exciter. The mechanism for bending an elongated body as set forth in claim 1, wherein said elongated body comprises a portion of an endoscope including an image fibre.

Inventors: HAYASHI KAZUHIKO C O OSAKA WOR, KANDA MASAHIKO C O OSAKA WORKS, MAEDA NAO-OMI C O OSAKA WORKS, SOGAWA ICHIRO C O OSAKA WORKS, YOTSUYA KORO C O OSAKA WORKS, HAYASHI, KAZUHIKO, C/O OSAKA WORKS, KANDA, MASAHIKO, C/O OSAKA WORKS, MAEDA, NAO-OMI, C/O OSAKA WORKS, SOGAWA, ICHIRO, C/O OSAKA WORKS, YOTSUYA, KORO, C/O OSAKA WORKS
Applicants: SUMITOMO ELECTRIC INDUSTRIES, SUMITOMO ELECTRIC INDUSTRIES LIMITED
Application year: 1988
Main classification: A61B1
IPC codes: G02B6, A61F2, A61B1