Probe Head Joint Construction for Endoscopically Inserting Ultrasound Probe

This invention relates generally to an ultrasound examination system employing an endoscopically inserting ultrasound probe to be introduced into a body cavity through a biopsy channel within an endoscopic insertion instrument, and more particularly to a probe head joint construction particularly suitably for connecting a bulky ultrasound scanner head securely to the distal end of an elongated flexible cord of an endoscopically inserting ultrasound probe.

Regarding ultrasound examination systems in use for acquiring information on intracorporeal tissues, it has been known to introduce an endoscopically inserting ultrasound probe into a body cavity through an endoscopic instrument channel or a biopsy channel which is provided within an endoscopic insertion instrument. An ultrasound examination system of this sort is largely constituted by an ultrasound probe, a probe controller and an ultrasound image observation terminal. For making ultrasound scans, the ultrasound probe is provided with an ultrasound scanner head at the tip end of a flexible cord. The ultrasound scanner head has an ultrasound transducer element housed in an end cap fixedly attached to the tip end of the flexible cord. The probe controller serves to control the operations of the ultrasound transducer element, and the ultrasound image observation terminal includes an ultrasound driver which drives the ultrasound transducer element for transmission of ultrasound pulses, along with a signal processor for processing received ultrasound echo signals into ultrasound images to be displayed on a monitor screen.

For placement in an endoscopic biopsy channel, a major part of the ultrasound probe is constituted by a flexible cord of a smaller diameter as compared with the inside diameter of the endoscopic biopsy channel. In an ultrasound scanning operation, while transmitting ultrasound pulse signals toward an intracorporeal portion of interest at predetermined intervals, return echoes are received and converted into electrical signals through the ultrasound transducer element to acquire information of intracorporeal tissues over a predetermined range. The ultrasound transducer element is scanned in a linear direction in a linear ultrasound scanning operation and in a radial or rotational direction in a radial ultrasound scanning operation. For a radial scan, the ultrasound transducer element needs to be put in rotation by means of a motor or other rotational drive means, which however is too bulky to be provided at the distal end of the ultrasound probe. Therefore, it is the usual practice to provide on the ultrasound probe a rotation transmission means, which permits to remote-control the rotation of the ultrasound transducer element, in cooperation with a rotational drive means and rotational angle detection means which are provided on the part of the probe controller of the ultrasound examination system. For this purpose, the probe controller may be provided separately from an ultrasound image observation terminal, or, if desired, may be assembled into an ultrasound image observation terminal as an integral part thereof.

As the rotation transmission means, it has been the general practice to provide on the ultrasound probe a flexible shaft which is connected to the ultrasound transducer element at its fore end. The flexible shaft of this sort is usually in the form of a hollow coil tube consisting of layers of tightly wound coils and internally providing a passage for a cable to be connected to the ultrasound transducer element. The flexible shaft is fitted in a flexible sheathing tube and rotatable therein to transmit its rotation to the distal end of the probe to rotate the ultrasound transducer element.

The ultrasound probe is provided with a connector at its proximal end for disconnectibly coupling same with the ultrasound controller. The connector is largely constituted by a fixed part which is connected to the sheathing tube, and a rotating part which is connected to the flexible shaft through an internal space of the fixed part. The probe controller is provided with a rotational shaft to be disconnectibly coupled with the rotating part of the connector, along with a retaining member which is located around the rotational shaft for fixedly holding the fixed part of the connector. A cable which is passed through the flexible shaft is electrically connected to the probe controller through electrode members provided in the rotating part. Accordingly, upon coupling the rotating part of the connector with the rotational shaft on the part of the probe controller, the electrodes of the rotating part are electrically connected with corresponding electrodes on the side of the rotational shaft.

The ultrasound scanner assembly at the distal end of the flexible cord of the probe has an ultrasound transducer element rotatably mounted within an end cap which connected to the sheathing tube of the flexible cord. The ultrasound is supported on a rotary member which is connected to the fore end of the flexible transmission shaft. The end cap of the ultrasound scanner assembly is formed of a synthetic resin material having excellent properties in acoustic characteristics, and its internal space is filled with an ultrasound transmission fluid medium. The end cap is securely fixed to the fore end of the flexible sheathing tube. The proximal end of the flexible cord is terminated with a tail end connector to be disconnectibly connected to the probe controller. The tail end connector is constituted by a ring-like stationary part which is connected to the sheathing tube, and a rotating part which is located within the fixed part and connected to the flexible transmission shaft. The stationary part of the tail end connector is fixedly connected to a stationary part of the probe controller, while the rotating part is rotationally coupled with a rotational drive means provided on the probe controller. A cable to or from the ultrasound transducer element is passed through the flexible transmission shaft and electrically connected with the probe controller through a pair of electrode members which are provided on the rotating part of the connector and which are connectible with corresponding electrode members on the part of the probe controller.

When the probe controller is operated to actuate the rotational drive of the rotational shaft, its rotation is transmitted to the flexible shaft through the rotating part of the connector, while the sheathing tube which is fitted on the flexible shaft is retained in a fixed state without rotating together with the flexible shaft. As will be understood from the foregoing description, in addition to the function of rotationally driving the flexible shaft, the probe controller has functions as a signal relay means.

Since the outside diameter of the ultrasound probe is restricted by the inside diameter of an endoscopic biopsy channel on the endoscope, the ultrasound transducer element can only have an active surface of a limited size for transmission and reception of ultrasound signals. From the standpoint of permitting ultrasound scans of tissues in deep positions, it is desirable for the ultrasound transducer element to have as broad an active surface area as possible. In this connection, in the case of a front loading type ultrasound probe which is designed to be placed in an endoscopic biopsy channel from an inverse direction, that is to say, from the fore distal end of an endoscopic insertion instrument, it is possible to employ a bulky ultrasound scanner assembly with a large-size ultrasound transducer element because in this case there is no necessity for passing the ultrasound scanner assembly through the narrow endoscopic biopsy channel in a preparatory stage prior to introduction into a body cavity.

When an ultrasound probe is assembled into a biopsy channel of an endoscope, the ultrasound scanner head of the probe is projected to a certain extent from an exit opening of the biopsy channel at the distal end of the endoscopic insertion instrument. If an ensuing flexible cord portion is projected out of the endoscopic biopsy channel, letting the ultrasound scanner head hang down unstably like a pendant, there may arise difficulties in introducing the endoscopic insertion instrument smoothly into a body cavity or in locating the ultrasound scanner head precisely in an aimed position within the body cavity. Therefore, there must be provided some measures which can retain the ultrasound scanner head stably at the distal end of the endoscopic insertion instrument. In this regard, if the projected flexible cord portion is retracted into the endoscopic biopsy channel by pulling the probe in the rearward direction, the ultrasound scanner head which is larger than the inside diameter of the endoscopic biopsy channel can be fixedly held against marginal edges of the exit opening of the biopsy channel as long as the pulling force is applied to the probe.

The end cap which accommodates an ultrasound scanner head assembly is connected to a sheathing tube of the flexible cord portion of the probe normally by the use of a joint ring member of a diameter substantially same as or slightly larger than the inside diameter of the sheathing tube. Normally, a fore end portion of the sheathing tube is fitted on and bonded to the joint ring member which is projected from the side of the end cap. In some cases, for the purpose of augmenting the strength of the bonded joint portion, line wrapping is formed by winding a thread or filament around the outer periphery of the sheathing tube. The end cap, which is formed of a synthetic resin material for excellent properties in acoustic characteristics, can be easily deformed if directly connected with the sheathing tube of the flexible cord, resulting in separation from the latter. For this reason, it is the general practice to connect the end cap with the sheathing tube of the flexible cord through a connecting or joint member of rigid metallic material, fitting the sheathing tube on the connecting member over a substantial length.

The sheathing tube of the flexible cord is small in diameter and formed of a soft synthetic resin which is difficult to bond to the metallic connecting member with sufficient strength of adhesion by the use of an adhesive. Even if line wrapping is formed on the connected end of the sheathing tube in addition to an adhesive, it still has a possibility of being separated from the connecting member when an unduly large force is exerted thereon from outside. Therefore, when the flexible cord of the probe is forcibly pulled into the endoscopic biopsy channel for the purpose of holding the endoscopic scanner head fixedly against the fore end of the endoscopic insertion instrument as mentioned hereinbefore, the end cap of the scanner head can be caused to come off the sheathing tube of the flexible cord by a reaction force as it is pushed against the fore end of the endoscopic insertion instrument. The ultrasound scanner head can be fixed at the fore end of the endoscopic insertion instrument by providing a rubber ring or other stopper member around a flexible cord portion behind the ultrasound scanner head in such a way it functions as a stopper for the scanner head by frictional contact with inner surfaces of the endoscopic biopsy channel. Conversely, however, the provision of such stopper means makes it difficult to adjust the position of the ultrasound scanner head or to supply an ultrasound transmission fluid medium such as deaerated water into a body cavity through the endoscopic biopsy channel.

With the foregoing situations in view, it is an object of the present invention to provide a probe head joint construction for an endoscopically inserting ultrasound probe, which can prevent an end cap of an ultrasound scanner head from falling off a distal end portion of a flexible cord of the probe.

It is another object of the present invention to provide a probe head joint construction for an endoscopically inserting ultrasound probe, which can retain a bulky ultrasound scanner head, larger in diameter than an endoscopic biopsy channel, stably at a distal end of an elongated flexible cord of the probe.

It is still another object of the invention to provide a probe head joint construction for an endoscopically inserting ultrasound probe, which can retain a bulky ultrasound scanner head, larger in diameter than an endoscopic biopsy channel, stably and securely at a distal end of an elongated flexible cord of the probe despite application of an axial tensioning force which is constantly applied to the flexible cord to abut the scanner head against marginal edges of a front opening of the endoscopic biopsy channel.

In accordance with the present invention, there is provided a probe head joint construction for an endoscopically ultrasound probe to be introduced into a body cavity through a biopsy channel provided internally of an endoscopic insertion instrument, the ultrasound probe having a bulky ultrasound scanner head at the distal end of an elongated thin flexible cord having a cable sheathed in a soft flexible outer tube for placement in said endoscopic biopsy channel, and the ultrasound scanner head having an ultrasound transducer element housed in an end cap of a larger diameter than the endoscopic biopsy channel. The probe head joint construction according to the present invention essentially includes: a joint member of rigid metallic material extended on the proximal side of the end cap, and being formed in the shape of a hollow stepped cylinder including a front joint portion connected with the end cap and having a diameter substantially equivalent with that of the end cap, and a rear joint portion of a smaller diameter to be connected with the outer tube of the flexible cord by fitting engagement therewith, the rear joint portion being provided with a protuberance on the outer periphery thereof; the outer tube of the flexible cord being fitted on the rear joint portion of the joint member over and across the protuberance and firmly fastened to the rear joint portion by a couple of line wrappings formed therearound on front and rear sides of the protuberance.

Preferably, the protuberance is an annular protuberance provided approximately in an axially intermediate position on the circumference of the rear joint portion, and the line wrapping on the front side of the protuberance has a greater number of turns than the line wrapping on the rear side of the protuberance. In order for the outer tube of the flexible cord to present a smooth profile in the joint portion, a sunken portion of reduced diameter is provided on the outer periphery of the tube on which the line wrappings are to be formed.

The above and other objects, features and advantages of the present invention will become apparent from the following particular description of the invention, taken in conjunction with the accompanying drawings which show by way of example some preferred embodiments of the invention.

In the accompanying drawings:

FIG. 1 is a schematic illustration of the general layout of an ultrasound examination system with an endoscopically inserting ultrasound probe;

FIG. 2 is a fragmentary schematic view of an ultrasound probe and a coupling adaptor;

FIG. 3 is a fragmentary longitudinal section of a fore end portion of the ultrasound probe, with a stopper mechanism omitted for the sake of illustration of the ultrasound probe itself;

FIG. 4 is a longitudinal sectional view taken on line X--X of FIG. 3;

FIG. 5 is a longitudinal sectional view of a tail end portion of the ultrasound probe;

FIG. 6 is a schematic sectional view of a probe controller;

FIG. 7 is a schematic view of a probe clamper;

FIG. 8 is a longitudinal sectional view of the coupling adaptor;

FIG. 9 is a schematic sectional view of the ultrasound probe which is coupled with the probe controller through the coupling adaptor; and

FIG. 10 is a schematic sectional view of a joint portion of the ultrasound scanner head and flexible cord of the probe.

Hereafter, the present invention is described more particularly by way of its preferred embodiments shown in the drawings. Schematically shown in FIG. 1 is the general layout of an ultrasound examination system incorporating an ultrasound probe coupling adaptor according to the present invention. The ultrasound examination system is largely composed of an ultrasound probe 1, a probe controller 2 and an ultrasound image observation terminal 3 with a monitor screen 4. The ultrasound probe 1 is of the type which is introduced into a body cavity by way of an endoscope 5, more specifically, by way of a biopsy channel 6 which is provided axially and internally of an endoscopic insertion instrument 5b and accessible through an entrance housing 6a, which is provided on a manipulating head grip 5a of the endoscope 5. Led out from the manipulating head grip 5a of the endoscope 5 is a universal cable 5c to be connected to a light source and an ultrasound signal processor which are not shown in the drawings.

The ultrasound probe 1 as a whole is constructed as shown in FIG. 2. More specifically, as seen in FIG. 2, the ultrasound probe 1 is largely constituted by an ultrasound scanner head assembly 1a, a flexible cord 1b and a tail end connector 1c. As shown particularly in FIGS. 3 and 4, the ultrasound scanner head la is provided with an end cap 10. Connected to the end cap 10 is a joint member 11 which is formed of a rigid metallic material in the form of a hollow stepped cylinder having a front joint portion 11a of a large diameter and a rear joint portion 11b of a small diameter. The ultrasound transducer element 12 accommodated in the end cap 10, and mounted on a rotary member 13 which is rotatably supported within the end cap 10 through a bearing 14 to scan the ultrasound transducer element 12 in the radial direction. For accommodating a large-size ultrasound transducer element with a broad active surface area which can transmit strong ultrasound signals, the end cap 10 is of a bulky size having an outside diameter as larger than the inside diameter of the endoscopic biopsy channel 7 as possible within a range which would not obstruct the view field of endoscopic observation.

The flexible cord 1b is constituted by a flexible outer tube 15 of soft synthetic resin material or the like, and a flexible rotation transmission shaft 16 which is sheathed in the outer tube 15. Fixedly connected to the fore distal end of the outer tube 15 is the joint member 11 which is in turn fixedly connected to the end cap 10 at the opposite end thereof. The flexible transmission shaft 16 is constituted, for example, by tightly wound coils, preferably, by double layers of tightly wound coils of metal wires for transmitting rotations accurately in a reliable manner. The fore end of the outer tube 15 is fitted on the rear joint portion 11b of the joint member 11 and securely fastened to the latter by line wrapping 17, thereby fixedly connecting the end cap 10 at the fore end of the flexible cord 1b. The fore distal end of the flexible shaft 16 is securely fixed to a hollow rotary member 18 which is integrally connected to the rotary member 13. The ultrasound transducer element 12 is provided with a pair of electrodes 19a and 19b to connect signal lines 20a and 20b of a coaxial cable 20 which is passed through the neck member 18 and extended as far ss the tail end connector 1c of the probe 1 through the internal space of the flexible shaft 16.

Shown on an enlarged scale in FIG. 5 is the probe construction where the proximal end of the flexible cord 1b is terminated with the tail end connector 1c. More specifically, the proximal end of the outer tube 15 is fixedly fitted on a rigid pipe 21 of metal. The proximal end of the flexible shaft 16 is connected to a rotational ring assembly 22 including an electrode ring. In this instance, the ring assembly 22 is composed of four rotary members or rings 23 to 26 which are successively threaded one in another in the axial direction. The first rotary ring 23 which is directly connected to the flexible shaft 16 is formed of a rigid metallic material with a sufficient degree of shape retainability and received in the rigid pipe 21, which is similarly formed of a rigid metallic material, for sliding rotational movements therein. A seal member 27 is fitted on the first rotary ring 23 to seal off the clearance between the first rotary ring 23 and the rigid pipe 21 air- and liquid-tight. Connected to the first rotary ring 23 is a second rotary ring 24 which is formed of an electrically insulating material such as a synthetic resin material or the like. A third rotary ring 25 which is connected to the second rotary ring 24 is formed of a metal or other conducting material, while a fourth rotary member 26 which is connected to the third rotary ring 25 is formed of an electrically insulating material.

In this case, for the purpose of ensuring the sealing capacity by the seal member 27, the first rotary ring 23 is formed of a metal or metallic material. The third rotary ring 25 is formed of a metal because it is required to function as an electrode to be connected to the ultrasound transducer element 12. Accordingly, the second and fourth rotary members 24 and 26 of electrically insulating material are located on the front and rear sides of the third rotary ring 25. The coaxial cable 20 is passed internally through the ring assembly 22, with its core wire 20c connected to a pin 28, which is fitted in the fourth rotary member 26, and its shield wire 20d connected to the third rotary ring 25.

Further, a rotation transmission pin 29 is securely planted in the third rotary ring 25. As described hereinlater, the transmission pin 29 functions to transmit rotation to the ring assembly 22, and is arranged in such a way as to project radially outward from the outer periphery of the third rotary ring 25 by a predetermined length. A spacer ring 30 is fitted on the outer periphery of the ring assembly 22 between the rotation transmission pin 29 and the rigid pipe 21. This spacer ring 30 is abutted against the front side of the rotation transmission pin 29 and rear end face of the retainer shell 21, thereby to retain the ring assembly 22, the flexible shaft 16 which is connected to the ring assembly 22, the flexible tube 16 and the retainer shell 21 in an inseparably assembled state. The spacer ring 30 is formed of an electrically insulating synthetic resin material or the like with suitable slipperiness. Thus, by the spacer ring 30, the retainer shell 21 is electrically insulated from the third rotary ring 25 and the rotation transmission pin 29 which are both formed of a metallic material.

Referring now to FIG. 6, the probe controller 21 is provided with a casing 31 of an electrically insulating synthetic resin material or the like, in which a rotational shaft 32 is rotatably mounted through a bearing 33 to extend toward an opening 31a which is provided on the front side of the casing 31. Mounted on the rotational shaft 32 are a pair of gears 34 and 35. One gear 34 is meshed with a drive gear 37 which is mounted on an output shaft of an electric motor 36, while the other gear 35 is meshed with a follower gear 39 which is mounted on an input shaft of an encoder 38. Provided internally of the rotational shaft 32 is an electrode member 40 which is constituted by an inner pipe 41 and an outer pipe 42. These inner and outer pipes 41 and 42 are formed of an electrically conducting material and insulated from each other by an interposed insulating pipe 43. In addition, the outer pipe 42 is fitted in an insulating ring 44 which is fixedly fitted in the rotational shaft 32. Thus, by an adaptor 60 which will be described hereinlater, the core and shield wires 20c and 20d of the coaxial cable 20 are electrically connected to the inner and outer pipes 41 and 42, respectively.

The probe controller 2 which is arranged in the above-described manner is removably attached on the entrance passage 6 of the biopsy channel 7, which is provided on the housing of the manipulating head grip 5a of the endoscope 5. For this purpose, a cylindrical connecting piece 43 is provided on an arm 44 which is projected outward from the casing 31 of the probe controller 2, and removably fitted in an opening 8 of the entrance passage 6 of the endoscopic head grip 5a. The arm 44 is provided with hooks 45 to be detachably engaged with a flange 8a portion which is formed around the entrance opening 8 of the endoscopic biopsy channel 7 (FIG. 1). The hooks 45 are urged to embrace the flange portion 8a by the action of springs, which are not shown in the drawings, thereby to hold the probe controller 2 of the ultrasound probe 1 fixedly on the head grip 5a of the endoscope 5.

As seen in FIG. 1, the tail end connector 1c and ensuing proximal end portion of the flexible cord 1b of the ultrasound probe 1 are led out of the endoscopic biopsy channel 7 through an axial passage in the connecting piece 43 which is fitted in the entrance housing 6, and connected to a tensioning means 46. The proximal end portion of the flexible cord 1b behind the tensioning means 46 is loosely looped and connected to the probe controller 2 through a coupling adaptor 60. The tensioning means 46 includes an operating rod 46a which is provided with a probe clamp member 46b.

As clear from FIG. 7, the probe clamp member 46b is comprised of an arm 50 which is extended from the operating rod 46a, and an axially split holder pipe 51 is 5 which is gripped in a fore end portion of the arm 50. In turn, the flexible cord 1b coming out of the endoscopic biopsy channel 7 is passed through and releasably gripped in the holder pipe 51. Fitted on the holder pipe 51 is a clamp ring 52 which has flat clasp portions 52a at its opposite ends releasably fastened to each other by a screw 53. It follows that a proximal end portion of the flexible cord 1b of the ultrasound probe 1, outside the endoscopic biopsy channel 7, can be fixedly clamped by the clamp member 46b at an arbitrary position. The operating rod 46a is retractably mounted on the casing 31 of the probe controller 2, and constantly urged to protrude in the outward direction by the action of a spring 47 which is provided within the casing 31. The operating rod 46a can be pushed into and out of the casing 31 by way of a finger ring 46c which is provided at its outer end. Accordingly, when a proximal end portion of the flexible cord 1b is fixedly clamped by the clamp member 46b, the ultrasound probe 1 as a whole is constantly urged to retract toward the proximal end of the endoscopic biopsy channel 7 under the influence of the biasing action of the spring 47.

One end of the rotational shaft 32 is disposed in the opening 31a on the front side of the casing 31 as mentioned hereinbefore, while the other end of the rotational shaft 32 is connected to a rotary member 48a of a rotary connector 48 which is provided within the casing 31. A cable 9a from the cable assembly 9 is connected to a stationary member 48b of the rotary connector 48. Further, the stationary member 48b of the rotary connector 48 is fitted in a rotation blocking member 48c and thereby blocked against rotational movements with the rotary member and at the same time prevented from twisting or torsional deformations. A cylindrical connection housing 49 is erected around the opening 31a of the housing 31 in such a way as to circumvent the rotational shaft 32.

The tail end connector 1c of the ultrasound probe 1 is coupled with the above-described probe controller 2 not directly but through a coupling adaptor 60 as described below. The coupling adaptor 60 is provided with a first or front coupling mechanism at one end to be connected to the tail end connector 1c of the probe and a second or rear coupling mechanism at the other end to be connected to the probe controller 2. More specifically, as shown particularly in FIG. 8, the coupling adaptor 60 is provided with stationary members including an outer housing 61 of substantially cylindrical shape and a retainer cap 62 which is threaded into one end of the outer housing 61. These stationary members of the adaptor are securely fixable relative to the casing 31 of the probe controller 2. To this end, the outer housing 61 is provided with a stopper groove 61a which is engaged with a stopper projection 49a on the part of the connection housing 49 of the probe controller 2 to block relative rotations of the fixed member of the adaptor 60 when connected to the latter. Further, the retainer cap 52 of the adaptor 60 is provided with an axial hole 62a to receive the retainer shell 21 of the tail end connector 1c of the probe 1. The retainer cap 62 is provided with a plural number of radial through holes 62b in its front end wall across the axial hole 62a to receive fixing screws 63, which are retractably protrudable into the axial hole 62a. More specifically, the fixing screws 63 are urged into the protruding positions by biasing springs 65 which are charged between the respective fixing screws 63 and spring seats 64. The fixing screws 63 are pointed at the respective inner ends for engagement in axial grooves (not shown) which are provided on the outer peripheral surface of the retainer shell 21 of the tail end connector 1c as rotation blocking grooves. When tail end connector 1c is inserted into the axial hole 62a of the retainer cap 62 up to the retainer shell 21, the pointed ends of the fixing screws 63 are engaged with the stopper grooves to block rotations of the retainer shell 21 and the outer tube 16 of the probe 1 during radial ultrasound scans when the ultrasound transducer element 13 is rotated through the flexible shaft 17.

The coupling adaptor 60 is further provided with rotary members internally of its stationary members including the housing 61 and the retainer cap 62. Major rotary members are rear and front rotary members 66 and 67 of generally hollow cylindrical shapes. A socket assembly 68 is threaded into the front rotary member 67 to receive the tail end connector 1c of the ultrasound probe 1 therein. The front rotary member 67 itself is threaded into a retainer ring 69 which is fixedly connected to the rear rotary member 66 by a box nut 70. A first tubular electrode pin 71 of the socket assembly is threaded into the front rotary member 67, which is formed of an electrically insulating material. A tubular insulating member 72 is threaded into the first tubular electrode pin 71, and a second tubular electrode pin 73 is fitted in this tubular insulating member 72. The first and second electrode pins 71 and 73 are in the form of axially split pins with spring characteristics. Further, a radial drive pin 74 is provided on the front rotary is 5 member 67, the drive pin 74 being abutted against the rotation transmission pin 29 on the part of the tail end connector 1c of the ultrasound probe 1 when the latter is connected to the coupling adaptor 60. By abutting engagement of the drive pin 74 with the rotation transmission pin 29, rotation is transmitted from the rotary members of the coupling adaptor 60 to the ring assembly 22 on the tail end connector 1c. Thus, an interlocked rotation transmission mechanism is constituted by the drive pin 74 and the transmission pin 29.

On the other hand, a C-ring 75 is fitted on a proximal end portion of the rear rotary member 66, the C-ring 75 being engageable with an annular groove 32a around the inner periphery of a larger-diameter coupling portion, which is provided at the outer or front end of the rotational shaft 32, for retaining the adaptor 60 securely in the connected position relative to the probe controller 2, precluding the possibilities of its dislocations. Further, the distal end portion of the rear rotary member 66, on the proximal side of the C-ring, is formed in a spline profile for engagement in the inner periphery 32b of an outer end portion of the rotational shaft 32 which is formed in a corresponding spline profile. Indicated at 77 is a connector member which is fixedly provided within the rear rotary member 66. This connector member 77 is constituted by a tubular outer cover 78 and an electrode rod 79, each formed of a conducting material. An insulating ring 80 is interposed between the outer cover 78 and the electrode rod 79 which are connected to the first and second tubular electrodes 71 and 73 through wires 81 and 82, respectively. Both of the outer cover 78 and electrode rod 79 are in the form of an axially split tubular structure, and are resiliently coupled with the first and second tubular electrodes 71 and 73, respectively. The rotary and stationary members may be assembled together through a bearing. In this particular embodiment, the housing 61 and the rear rotary member 66 are retained in small gap relation with each other. In case the rear rotary member 66 is loosely fitted in the housing 61 in this manner, the connector member 77 can be easily and snugly fitted in the rotational shaft 32 as the housing 61 is brought into engagement with the connection housing 49 on the part of the probe controller 2.

With the probe coupling adaptor of the construction as described above, for the purpose of transmitting ultrasound signals of lower frequency and higher power, the ultrasound probe 1 can employ an ultrasound transducer element 13 of a large size having a broader active surface area within the end cap 10 of on the ultrasound scanner assembly which is much larger than the inside diameter of the biopsy channel 7 on the endoscope 5.

In a preparatory stage prior to introduction into a body cavity of the insertion instrument 5b of the endoscope 5, the ultrasound probe 1 is placed in the endoscopic biopsy channel 7 through an opening at the distal end of the endoscopic insertion instrument 5b, drawing out the tail end connector 1c through the entrance way 6 on the manipulating head grip 5a of the endoscope 5. The proximal end portion of the flexible cord 1b, including the tail end connector 1c, which has been drawn out of the endoscopic biopsy channel 7 is threaded through the axial passage 43a in the connecting piece 43 on the probe controller 2. The flexible cord 1b is then clamped in the clamp member 46b of the tensioning means 46 at a suitable position before coupling the tail end connector 1c with the coupling adaptor 60. After this, the coupling adaptor 60 is connected to the probe controller 2. As a result, as shown in FIG. 9, the ultrasound probe 1 is electrically and rotationally coupled with the probe controller 2 through the coupling adaptor 60, permitting to rotationally drive the ultrasound transducer element 12 from the probe controller 2 and to transfer electrical signals between the ultrasound transducer element 12 and the ultrasound image observation terminal 3.

More specifically, upon connecting the rear rotary member 66 and housing 61 of the adaptor 60 with the rotational shaft 32 and connection housing 49 on the casing 31 of the probe controller 2, respectively, the connector member 77 is coupled with the electrode member 40 on the probe controller 2. Consequently, rotation of the rotational shaft 32 is transmitted to the ring assembly 22 of the ultrasound probe 2 through the rear and front rotary members 66 and 67 of the adaptor 60, and then to the flexible transmission shaft 16 which is connected with the rotating ring assembly 22. The signal lines 20a and 20b of the coaxial cable 20, to and from the ultrasound transducer element 13, are electrically connected with the first and second tubular electrodes 71 and 73 through the electrode pin 28 and the transmission pin 29, which are electrically connected with the inner and outer cover tubes 79 and 78 of the connector member 77 and the inner and outer pieces 41 and 42 of the electrode member 40 on the probe controller 2 through the wires 81 and 82, which are electrically connected with the ultrasound image observation terminal 3 through the rotary connector 48 and the cable 9.

In order to carry out an ultrasound scan or scans, after introducing the insertion instrument 5b of the endoscope into an intracavitary examination site, the ultrasound scanner assembly 1a which is projected from the distal end of the endoscopic insertion instrument 5b is abutted against an intracavitary wall. Then, the ultrasound transducer element 12 is put in rotation by remote control from the probe controller 2. At the same time the ultrasound transducer element 12 is driven to transmit ultrasound pulses into the patient's body at predetermined angular intervals, while converting received return echoes into electrical signals. At the ultrasound image observation terminal 3, the return echo signals from the ultrasound transducer element 12 are processed into video signals to display ultrasound images of body tissues on the monitor screen 4.

Thus, during a scanning operation, the ultrasound scanner head 1a of the probe 1 in the biopsy channel 7 of the endoscope 5 is projected from the distal end of the endoscopic insertion instrument 5b. However, if at this time part of the flexible cord 1b is also projected from the endoscopic insertion instrument 5b, it becomes extremely difficult to control the position of the ultrasound scanner head 1a, which is allowed to hang down unstably from the distal end of the endoscopic insertion instrument. This unstable state of the scanner head 1a makes it difficult not only to introduce the endoscopic insertion instrument smoothly into an intracavitary examination site but also to orient the ultrasound scanner head 1a toward an intracavitary region to be examined. Therefore, at the time of a scanning operation, the ultrasound scanner head 1a should be fixedly retained at the distal end of the endoscopic insertion instrument 5b substantially as an integral part of the latter. The fixation of the ultrasound scanner head 1a integrally at the distal end of the endoscopic insertion instrument 5b has a great importance in consideration of the fact that the endoscope 5 is usually provided with an angle section in a fore end portion of its insertion instrument for angularly flexing the fore end of the insertion instrument toward a desired direction, permitting to turn the ultrasound scanner head 1a into the desired direction simultaneously with the flexing operation on the angle section of the endoscope 5.

For this purpose, the flexible cord 1b of the ultrasound probe 1 is constantly applied with a predetermined tensioning force by the tensioning means 46 which is provided on the probe controller 2, urging the flexible cord 1b to retract into the endoscopic biopsy channel 7. In order to apply a tension to the flexible cord 1b of the probe 1, the operating rod 46 is pushed into the casing 31 by way of the finger ring 46c before clamping a predetermined proximal end portion of the flexible cord 1b in the probe clamp member 46b. In this state, upon releasing the finger ring 46c, the operating rod 46a is pushed back into the outer projecting position by the action of the biasing spring 47, thereby applying to the flexible cord 1b a tensioning force acting to retract the flexible cord 1b into the endoscopic biopsy channel 7 until the ultrasound scanner head 1a is abutted against the distal end face of the endoscopic insertion instrument 5b. At this time, since the ultrasound scanner head assembly 1a is larger than the inside diameter of the endoscopic biopsy channel 7, it is pushed against marginal edge portions of the exit opening of the biopsy channel 7 and fixedly held against the distal end face of the endoscopic insertion instrument 5b.

However, if the ultrasound scanner head 1a is pushed directly against the distal end face of the endoscopic insertion instrument 5b, the ultrasound scanner head 1a can be subjected to a reaction force which acts to pull the scanner head 1a way from the flexible cord 1b, that is to say, to disjoin the scanner head 1a from the flexible cord 1b. More particularly, as the radial surface 11c of the joint member 11 is directly pressed against the distal end face of the endoscopic inseriton instrument 5b, the rear joint portion 11b of the joint member 11 which is fitting engagement with the outer tube 15 of the flexible cord 1b could be disjoined from the latter by a reaction force. In order to prevent troubles of this sort, it is necessary to increase the strength of the joint construction of the joint member 11, especially the rear joint portion 11b of the joint member 11 in fitting engagement with the flexible cord 1b of the probe 1. According to the present invention, the strength of the joint portion between the ultrasound scanner head 1a and the outer tube 15 of the flexible cord 1b is improved by a joint construction as shown in FIG. 10.

Firstly, as seen in that figure, the rigid tip end section of the insertion instrument 5b of the endoscope 5, which is connected to the fore end of the angle section, has a certain axial length to accommodate components of an endoscopic image pickup system such as objective lens, solid-state image sensor etc. Since the ultrasound probe 1 is placed in the endoscopic biopsy channel 7 when in us, a fore end portion of the probe 1 to be located within the rigid tip end section of the endoscope 5 is not necessarily required to have flexibility. Further, since the ultrasound scanner head 1a of the probe 1, which is always projected forward of the endoscopic biopsy channel 7, at least a fore end portion of the joint member 11 which is located within the rigid tip end section of the endoscopic insertion instrument 5b has no possibility of being bent in a particular direction even if the step-like radial surface 11c of the joint member 11 is abutted against the distal end face of the endoscopic insertion instrument 5b. Therefore, the length of the rear joint portion 11b of the joint member 11 of rigid metal is increased to a maximum possible length for the purpose of increasing the length of its fitting engagement with the outer tube 15 of the flexible cord 1b. The increase in fitting engagement makes it possible to increase the joint strength. The outer tube 15 is fitted on the rear joint portion 15 of the joint member 11 and bonded to the latter by the use of an adhesive. In addition, line wrapping 17 is formed on the outer tube 15 so that the tube 15 which is formed of a soft and flexible material is compressed and tightly fastened to the outer periphery of the rear joint portion 11b.

Besides, the rear joint portion 11b is provided with an annular protuberance 90 of a predetermined height around its outer periphery substantially at an axially intermediate position, more specifically, at an axially intermediate position a little closer to its proximal end. The outer tube 16 is fitted over and across the annular protuberance 90 and extended as far as the radial surface 11c at the border between the front and rear joint portions 11a and 11b of the joint member 11. The above-described line wrapping 17 is formed around the outer periphery of the outer tube 15 except the annular protuberance 90. In other words, the line wrapping 17 is divided into front line wrapping 17a and rear line wrapping 17b by the annular protuberance 90.

The front line wrapping 17a on the front side of the annular protuberance 90 is formed fully to the distal end of the outer tube 15, but the rear line wrapping 17b on the rear side of the annular protuberance 90 is terminated at a position short of the proximal end of the rear joint portion 11b. It is preferred for the rear line wrapping 17b not to be extended to the proximal end of the rear joint portion 11b because, if extended, the strong fastening force of the line wrapping could deform the joint portion. It follows that the front line wrapping 17a has a greater number of turns and a larger width than the rear line wrapping 17b. Consequently, when the ultrasound probe 1 is assembled into the endoscope 5, the joint portion has an extremely high strength particularly against a tensile force acting in the direction indicated by an arrow in FIG. 10.

The outer tube 15 is firmly pressed against the rear joint portion 11b only in those portions which are under the line wrapping 17, and the remainder of the tube 15 is free of the pressing force of the line wrapping 17. The tube portions which are gripped by the compressing force of the front and rear line wrappings 17a and 17b are restrained of axial movements by the annular protuberance 90, which functions as a stopper preventing the tube 15 from slipping along the surface of the rear joint portion 11b of the joint member 11 even when a strong pulling force is applied thereto. As a result, the joint strength of the outer tube 15 and the rear joint portion 11b is enhanced to a considerable degree to preclude the possibilities of the joined parts being separated by the tensioning force which is constantly applied to the flexible cord 1b of the probe 1 in a direction backward of the endoscopic biopsy channel 7 for retraction thereinto every time and all the time when the ultrasound probe 1 is assembled into the endoscope 5 for an ultrasound examination.

The fore end portion of the outer sheathing tube 15 which is in fitting engagement with the rear joint portion 11b of the joint member 11 is deformed to conform with the profile of the annular protuberance 90 under the pressures of the front and rear line wrappings 17a and 17b. Obtrusive thickening or bulging of the outer tube 15 in this fitted fore end portion is not desirable because it may make it difficult to supply a liquid into a body cavity through a gap space or spaces between the flexible cord 1b and the inner surfaces of the endoscopic biopsy channel 7. Therefore, for the purpose of preventing part of the fitting fore end portion of the outer tube 15 from bulging out in the radial direction, the outer tube 15 is thinned down to provide a sunken or portion 91 of reduced diameter on the outer periphery of its fitting end portion substantially over the entire length thereof. In this regard, it is desirable to reduce the thickness of the fitting end portion of the outer tube 15 to an extent which is slightly larger than the diameter of the filament or thread which is used for the line wrappings 17a and 17b. This reduction in thickness or diameter prevents the fitting end portion of the outer tube 15 from bulging out to any objectionable degree even after application of the line wrappings 17a and 17b and an adhesive 92 which cements the respective line wrappings 17a and 17b in position on the outer periphery of the outer tube 15. The annular stopper protuberance 90 which is free of the line wrappings 17a and 17b would not protrude radially outward of the remainder of the joint portion if its radial height is limited to a measure corresponding to the amount of reduction in diameter of the small diameter portion 91. Accordingly, the fore end portion of the outer sheathing tube 15 which is fitted on the rear joint portion 11b can present a smooth profile almost free of ups and downs in radial directions. The annular protuberance 90 can function as a stopper satisfactorily as long as it has a height corresponding to the diameter of the thread or filament of the line wrappings 17a and 17b.