WO2022008445A1

WO2022008445A1 - Deflection control mechanism for a steerable flexible endoscope, steerable flexible endoscope, endoscope assembly set, and method for assembling a flexible endoscope

Info

Publication number: WO2022008445A1
Application number: PCT/EP2021/068516
Authority: WO
Inventors: Alar MÄESARAPU; Johan TOMBERG
Original assignee: Karl Storz Se & Co. Kg
Priority date: 2020-07-08
Filing date: 2021-07-05
Publication date: 2022-01-13
Also published as: DE102020118048A1; EP4178411A1

Abstract

The invention relates to a deflection control mechanism (29) for a steerable flexible endoscope (10), the endoscope (10) having an elongate flexible shaft (30) comprising a steerable section (31) that is deflectable by movement of at least one pair of counteracting control wires (37, 37', 38, 38'), the deflection control mechanism (29) comprising a support structure, a drive wheel rotatably supported in or on the support structure, and an elongate traction element having a flexible section, a first coupling section connected to a first end of the flexible section, and a second coupling section connected to a second end of the flexible section, wherein the flexible section of the traction element engages with the drive wheel, wherein the first and second coupling sections each comprise a fixation element for fixing a respective proximal end of each wire of the at least one pair of control wires (37, 37', 38, 38'), wherein at least one of the first and second coupling sections comprises a movable stop element co-operating with a fixed stop of the support structure, and wherein the support structure comprises at least one base plate arranged substantially in a base plane extending at least approximately perpendicular to a rotational axis of the drive wheel, wherein the base plate supports the fixed stop. The invention also relates to a steerable flexible endoscope (10), to an endoscope assembly set, and to a method for assembling a flexible endoscope (10).

Description

Deflection control mechanism for a steerable flexible endoscope, steerable flexible endo- scope. endoscope assembly set and method for assembling a flexible endoscope

The present invention relates to a deflection control mechanism for a steerable flexible en- doscope, to a steerable flexible endoscope having such a deflection control mechanism, to an endoscope assembly set, and to a method for assembling a flexible endoscope.

Flexible endoscopes comprise a flexible elongated shaft that is configured for being inserted into an internal cavity of a human or animal body or any other object. In a distal (i.e. distant from a user) end section of the shaft an imaging optics is arranged for generating an image of a scene in the cavity being observed. The endoscopic image generated may be transmitted to a proximal (i.e. close to the user) end of the shaft by a bundle of optical fibers to be picked up by an electronic image sensor positioned in a handpiece arranged at the proximal end of the shaft, or an electronic image sensor may be arranged in the distal end section of the shaft, the image signal being transmitted by electric lines arranged inside the shaft. A flexible en- doscope usually comprises an illumination system for illuminating the cavity to be observed, and one or more instrument and/or fluid channels extending from the handpiece through the shaft to its distal end.

Flexible endoscopes are typically employed for observing a cavity being accessed through a curved path, or to observe the interior of an organ that itself has a curved shape such as the intestine, for example. Due to its flexibility the flexible shaft is able to adapt during insertion to the curvature of the access path or the organ. Frequently, however, it is desirable to be able to actively deflect or bend the distal end section of the flexible shaft out of a straight alignment into a bent or articulated shape, in order to facilitate insertion through a curved access path or organ. Moreover, as a viewing direction of the imaging optics generally is determined by a direction of the distal end section of the endoscope shaft, active deflection of the distal end section permits observing a desired partial area of the cavity, and may permit substantially complete observation of the surface of the cavity by varying a deflection angle of the distal end section. Endoscopes permitting active deflection or bending of a section of the flexible shaft are usually denoted “steerable endoscopes”.

A steerable or deflectable section of the shaft of a steerable endoscope typically has a sup- porting structure of consecutively jointed pivoting elements, for example, wherein the piv- oting elements can be tipped toward one another by axially movable control wires. Alterna- tively, the supporting structure may be formed by one or more elastic bending elements, for example, which can be bent by the action of control wires. The supporting structure is en- closed in a flexible sheath made of a synthetic material, for example. Deflection of the steer- able section from an aligned position into a bent or articulated shape in one or an opposite direction can be controlled by reciprocating movement of one pair of counteracting control wires. Frequently, steerable endoscopes permit bending the steerable section in two perpen- dicular planes by operation of two pairs of control wires. The control wires may be fed along the outside or inside of the pivoting elements and extend through the shaft in a proximal direction into the handpiece where a deflection control mechanism is provided. The deflec- tion control mechanism effects movement of the control wires under user control, for exam- ple by turning one or more hand wheels.

Due to the design of the pivoting elements or the elastic bending elements and/or due to requirements of the flexible sheath or other elements of the shaft having a minimal bending radius, articulation of the steerable section is limited to a maximal permissible deflection angle. During operation of the steerable endoscope, however, a user normally has no direct visual control of the articulation of the steerable section. Thus steerable endoscopes have been provided having a deflection control mechanism that comprises a mechanical stop, in order to avoid exceeding the maximal permissible deflection angle and thus to avoid break- age or inadmissible deformation of components. Flexible steerable endoscopes are available having a large variety of shaft lengths, shaft di- ameters, internal designs including instrument and/or irrigation channels, and shaft stiff- nesses, as well as lengths, diameters, designs, stiffnesses, and maximal deflection angles of the steerable section. In each case, longitudinal movement of the control wires may be lim- ited to a particular range corresponding to a particular maximal deflection angle. On the other hand, for reasons of cost it would be desirable to employ standardized components for a variety of endoscopes.

European patent EP 2 835 096 B1 discloses a bending angle adjustment mechanism for set- ting a maximum bending angle of an endoscope. The mechanism is for adjusting a moving amount and a moving range of bending operation wires and chains, in a bending operation mechanism for performing a bending operation of a bending portion of the endoscope. The bending angle adjustment mechanism comprises a stopper member that restricts movement of the bending operation wire, and a screw member that performs positional adjustment by moving a position of the stopper member along a moving direction of the operation wire.

According to European patent application EP 3 222 195 A1 an endoscope has a bending adjustment unit comprising a stopper portion and a contact part coming into contact with the stopper portion, thereby regulating movement of a chain to which bending wires are coupled. A bending operation mechanism and the bending adjustment unit are provided on a flat sur- face side of a main frame that is formed in a plate shape. Further, a chain cover is provided that is formed in a plate shape, and a lid member formed by a third plate member is disposed on an end surface of a standing second chain housing wall.

The prior art deflection control mechanisms of steerable flexible endoscopes have proven to be not optimal regarding assembly and maintenance. In particular, each type or size of en- doscope requires a dedicated high-level assembly comprising a mechanical stop arrangement that is adapted to the permissible range of deflection angles of that particular type or size of endoscope, thus creating additional stock and manufacturing planning issues. Moreover, in prior art deflection control mechanisms tactile feedback to a user frequently is insufficient, such that the user does not clearly feel when a maximal permissible deflection angle has been reached, and may have the impression that increasing the force applied to a hand wheel of the deflection control mechanism may further increase the bending angle. This may lead to failure of the endoscope.

It is therefore an object of the present invention to provide a deflection control mechanism for a steerable flexible endoscope in which one or more of the above mentioned drawbacks are avoided or alleviated. In particular, it is an object of the invention to provide a deflection control mechanism being improved regarding assembly and/or maintenance, and/or having a more clearly defined and more rigid stop. Further objects of the invention are to provide a steerable flexible endoscope having an improved deflection control mechanism, a corre- sponding endoscope assembly set, and an improved method for assembling a flexible endo- scope.

These objects are met by a deflection control mechanism according to claim 1, by a steerable flexible endoscope according to claim 13, by an endoscope assembly set according to claim 14, and by a method according to claim 15. Particular embodiments of the present invention are indicated in the dependent claims.

The present invention relates to medical endoscopes, i.e. to endoscopes designed for medical applications, such as, for example, minimally invasive surgery and/or medical examinations. A user of the endoscope therefore typically is a surgeon conducting an endoscopic interven- tion. However, the present invention also relates to endoscopes designed for non-medical purposes, for example to industrial endoscopes or borescopes.

According to an aspect of the present invention, a deflection control mechanism is config- ured for controlling a deflection or articulation or a bending angle of a steerable section of a shaft of a steerable flexible endoscope. The shaft of the endoscope is an elongate, flexible shaft that is configured for being inserted into an internal cavity of a human or animal body or another object, for example a technical object, and comprises a steerable section that can be actively bent or deflected with respect to other sections of the shaft. In particular, the steerable section may be actively deflectable with respect to an adjacent section of the flex- ible shaft under user control. The steerable section may form a distal end section of the shaft, or a section close to the distal end of the shaft, for example. The steerable section may com- prise an imaging optics, or an imaging optics may be arranged in an end cap arranged at a distal end of the steerable section, such that by deflecting the steerable section a viewing direction of the imaging optics can be varied. The endoscope may further comprise a hand- piece connected to a proximal end section of the shaft, the handpiece having control elements for controlling various functions of the endoscope. An endoscopic image generated by the imaging optics may be transmitted by optical or electronic means to the handpiece. The de- flection control mechanism is connectable to the proximal end section of the shaft, and may be accommodated in the handpiece.

The steerable section of the shaft of the flexible endoscope is deflectable by longitudinal movement of at least one pair of counteracting control wires. The steerable section may have a supporting structure of pivoting or elastic elements, for example, which can be angled or bent due to a longitudinal force or a bending moment exerted by the control wires. Typically, the two wires of the pair of counteracting control wires are arranged on opposing sides of the supporting structure, preferably approximately symmetrically to a longitudinal axis of a respective part of the shaft. For controlling the deflection or bending of the steerable section the control wires are movable relative to the shaft substantially in their respective longitudi- nal direction, which direction usually is parallel to the axial direction of the respective part of the shaft. Thus, when a first one of the two wires of the pair is pulled in the proximal direction for deflection to one side, the other one will move in the distal direction; for de- flection to the opposite side, the other one of the two wires is pulled in the proximal direction, while the first one will move in the distal direction. Deflection of the steerable section from an aligned position into a bent or articulated shape in one or an opposite direction, or vice versa, can be controlled by such opposing or counteracting movement of the two wires of the pair of control wires. The control wires are guided in the shaft to the proximal end of the shaft, being operable in such opposing or counteracting manner by the deflection control mechanism connectable to the proximal end of the shaft. The control wires may also be denoted pull wires, referring to a pulling action of the wires, i.e. a force directed in a proximal direction, or push-pull wires, if the wires are configured similar to Bowden wires for also exerting a force in a distal direction. The deflection control mechanism comprises a support structure, a drive wheel rotatably supported in or on the support structure, and an elongate traction element. The drive wheel is rotatably supported in or on the support structure, for example with one or more bearings, having a rotatable axle or shaft or an axle fixed to the support structure. The support structure preferably is rigid. The support structure may comprise, for example, a non-rotating axle of the drive wheel, a cage structure in which the drive wheel is housed, and/or elements of a housing of the handpiece. The traction element comprises a flexible section and a first and a second coupling section. The flexible section may be configured as a chain, for example. The flexible section has a first end and a second end opposite the first end. The first coupling section is connected to the first end, and the second coupling section is connected to the second end of the flexible section. Preferably the flexible section and the first and second coupling sections have high stiffness in a longitudinal direction.

The flexible section of the traction element engages with the drive wheel, in particular with a circumferential surface of the drive wheel, such that by turning the drive wheel the first and second coupling sections are moved lengthwise. The drive wheel may be configured as a sprocket and the flexible section as a chain, the teeth of the sprocket engaging with the chain segments to move the chain in its length direction. Preferably the flexible section is wound around the drive wheel, encircling an angle of about 180° or an angle of about 180° plus an integer multiple of 360°, such that the traction element approximately is arranged in a “U” shape, or an angle exceeding 180°, for example an angle between 180° and 200° or 220°, to improve coupling with the drive wheel while providing a compact design. Both coupling sections may be at least approximately parallel to each other, defining a common longitudinal direction. By rotating the drive wheel the coupling sections therefore are moved in the longitudinal direction in an opposing manner. The drive wheel may be coupled with a hand wheel, for example, for being rotated manually by the user. Alternatively or addition- ally, the drive wheel may be coupled or configured for being coupled with a motor for being rotated in a motorized or robotic manner. Thus, for example, the flexible endoscope may be configured for being arranged at a robotic arm, such that the deflection control mechanism can be operated for controlling articulation of the steerable section in a robotic manner. The first and second coupling sections are configured for being coupled with the at least one pair of counteracting control wires. To this end the first and second coupling sections each comprise a fixation element for fixing a respective proximal end of each wire of the at least one pair of counteracting control wires. The fixation element may be configured as a rectan- gular fixation block, for example, comprising a longitudinal bore in which the proximal end section of the respective control wire can be clamped or in which a clamping element or a ferrule holding the wire can be fixed. When connecting the deflection control mechanism to the shaft of the steerable endoscope, both wires are fixed in the respective fixation element. Thus, by rotating the drive wheel the deflection angle of the steerable section of the shaft is controllable.

Further, at least one of the first and second coupling sections comprises a movable stop element co-operating with a fixed stop of the support structure to limit a range of movement of the respective coupling section and thus to limit a range of longitudinal movement of the respective control wire. As the movable stop element is comprised by the respective coupling section, during operation of the deflection control mechanism it is co-moving with the re- spective fixation element and with the respective control wire fixed to the fixation element. The fixed stop or stopper is formed or supported by the support structure and therefore re- mains in a fixed position during operation. The movable stop element co-operates with the fixed stop to define a limit to a movement of the traction element and thus to limit the move- ment of the control wires. In particular, the movable stop element may be stopped by con- tacting the fixed stop when the end of a permissible range of movement of the control wires has been reached. In this way deflection of the steerable section is limited to a maximal deflection or articulation angle, at least to one side of the shaft. Preferably, the first and the second coupling sections each comprise a movable stop element co-operating with a respec- tive fixed stop of the support structure to limit a range of movement of the respective cou- pling section, thus limiting a range of movement of the control wires in proximal as well as in distal direction. In this way deflection of the steerable section can be limited to a maximal deflection angle to one side as well as to an opposite side of the shaft. According to this aspect of the invention, the support structure comprises at least one base plate arranged substantially in a base plane, the base plane extending at least approximately perpendicular to a rotational axis of the drive wheel. The base plate may be substantially planar, having protrusions and/or bores and/or cutouts, and may have a larger extension in the longitudinal direction, i.e. parallel to the direction of movement of the coupling sections, than in a transverse direction. The base plate may be formed in one piece.

Moreover, in accordance with this aspect of the invention, the base plate supports the fixed stop of the support structure. The fixed stop may be an element connected to the base plate, or the fixed stop may be formed by a protrusion or shoulder of the base plate and thus be integral with the base plate. In particular, the fixed stop is situated on a side of the base plate being directed towards the at least one of the first and second coupling sections comprising the movable stop element. Further, the fixed stop is preferably arranged close to the drive wheel and can be rigidly connected to an axle of the drive wheel or a cage structure housing the drive wheel. Most preferably, the first and second coupling sections each comprise a movable stop element co-operating with a respective fixed stop of the support structure, wherein the base plate supports both fixed stops.

The deflection control mechanism may comprise further elements, such as a brake, for ex- ample. A brake permits blocking one or both control wires of the at least one pair of coun- teracting control wires in their respective longitudinal positions, such that the steerable sec- tion of the endoscope is fixedly held at a corresponding deflection angle. The deflection control mechanism may comprise a tensioning mechanism for pre-tensioning the at least one pair of control wires, the tensioning mechanism being included in the first and/or second coupling section, for example. The deflection control mechanism may be configured for ef- fecting movement of more than one pair of counteracting control wires. Preferably the de- flection control mechanism is operable manually by turning one or more hand wheels, and/or may be operable in motorized or robotic manner. A shaft coupling may be provided at a distal side of the handpiece or the deflection control mechanism for coupling the endoscope shaft to the handpiece and/or the deflection control mechanism. Due to the support structure comprising at least one base plate arranged at least approxi- mately perpendicular to a rotational axis of the drive wheel, the base plate supporting the fixed stop of the support structure to co-operate with the movable stop element of the traction element, a particularly simple, compact, and rigid design can be provided. Thus, the me- chanical stop limiting the range of deflection angles can be defined more rigidly, such that a user operating the steerable endoscope may receive a clearer tactile feedback when a maxi- mal deflection angle has been reached. In particular, when reaching the limit, a hand wheel being turned manually by the user for operating the deflection control mechanism cannot be turned perceivably further even by exerting an increased torque on the hand wheel. Thereby operation of the deflection control mechanism can be facilitated. Further, due to increased stiffness, breakage of components during operation can be more safely avoided.

Depending on a particular intended application, steerable endoscopes have different shaft diameters, different shaft lengths, different maximal deflection angles, and/or may differ in further properties, and therefore have different permissible ranges of longitudinal movement of the control wires. The longitudinal positions of the one or both fixed stops, relative to the respective movable stop element, are preferably determined such that a permissible maximal deflection angle of a particular endoscope shaft cannot be exceeded. Due to the base plate supporting the one or both fixed stops of the support structure, the deflection control mech- anism may be adaptable to a particular type or size of endoscope shaft having a particular range of movement of the control wires by selecting or machining the base plate accordingly, while all other elements of the deflection control mechanism may be suitable for a variety of types or sizes of shafts, being standardized in this sense. Further, the deflection control mechanism may be adaptable to a different type or size of endoscope shaft by only exchang- ing the base plate, while all other elements remain unchanged. In this way manufacturing stock and planning expenses may be reduced.

Preferably, the movable stop element of the at least one of the first and second coupling sections is adjustably connected to the fixation element of the respective coupling section. In particular a longitudinal position of the movable stop element relative to the fixation ele- ment can be adjusted, for example, by the movable stop element being mounted on a threaded rod extending substantially in the longitudinal direction of the respective coupling section and connected to the fixation element of the respective coupling section, wherein the movable stop element can be adjusted by turning or screwing it on the threaded rod in prox- imal or distal direction. In particular, the deflection control mechanism is configured such that the relative position of the movable stop element can be adjusted during assembly or maintenance. On the other hand, the fixed stop generally has a position pre-determined by design of the base plate and thus is not adjustable. Due to the co-operation of the movable stop element with the fixed stop, a limit of movement of the respective control wire can be adjusted in this way, at least in either proximal or distal direction. Most preferably, the first and second coupling sections each comprise a movable stop element co-operating with a respective fixed stop of the support structure, and both movable stop elements are adjustably connected to the respective fixation element of the respective coupling section. In this way the maximal range of movement of the control wires in proximal as well as in distal direction can be adjusted, preferably during assembly or maintenance.

Due to the movable stop element being adjustably connected to the respective fixation ele- ment of one or both coupling sections, a range of movement of the control wires can be further adjusted. Thus the deflection control mechanism may be adaptable in a further man- ner to a variety of shafts of steerable flexible endoscopes and/or permit adjustment due to manufacturing tolerances and service requirements. Moreover, the base plate may be con- figured such that the fixed stop only approximately defines a permissible range of movement of the control wires, while the movable stop element is adjustable for fine-tuning and/or service re-adjustment of the range of movement. In this way manufacturing cost can be fur- ther reduced.

In accordance with an advantageous embodiment, the flexible section and the first and sec- ond coupling sections of the traction element extend at least approximately in or adjacent and substantially parallel to the base plane. In particular, the longitudinal movement of the coupling sections may be effected parallel to the base plane. Further in accordance with this embodiment, the base plate is arranged substantially between the first and second coupling sections of the traction element. In particular, the traction element may be arranged substantially in a “U” shape, wherein the base plate is arranged between the first and second coupling sections, i.e. in an inner space of the “U”, and the fixed stop is situated on the base plate at an inner side of the “U”. Thus the fixed stop can be arranged close to the drive wheel and can be more directly and rigidly connected to an axle of the drive wheel. The fixed stop may be formed by a protrusion or shoulder of the base plate and thus be integral with the base plate, being formed on a longitudinal side of the base plate directed towards the respec- tive coupling section. In this way a particularly simple, stiff and rigid design can be achieved, providing a still more rigid and clearer definition of the mechanical stop provided by the movable stop element co-operating with the fixed stop.

Preferably the base plate is formed of metal, for example as one piece of sheet metal, and the support structure comprises at least one plastic plate arranged substantially parallel and adjacent to the base plate. The plastic plate may be formed in one piece. The plastic plate may be substantially planar and may have protrusions and/or bores for alignment and fixa- tion with respect to the base plate. The plastic plate may have a larger extension in the lon- gitudinal direction than in a transverse direction. The support structure may comprise two plastic plates arranged on either side of the base plate. Preferably the one or two plastic plates is or are arranged between the first and second coupling sections, i.e. when the traction ele- ment forms a “U” shape, in an inner space of the “U”. Advantageously the one or two plastic plates is or are arranged immediately adjacent to or abut the base plate. In particular, the metal plate and the at least one plastic plate are stacked upon one another. The one plastic plate may be stacked upon the base plate and, in case that two plastic plates are provided, the base plate may be stacked on the other plastic plate, providing a friction fit. Preferably the respective plates rest directly upon one another, forming two-dimensional contact areas to improve the friction fit. The one or two plastic plates may be fixed to the base plate by one or more pins, bolts and/or screws, for example, to increase rigidity. The stack of the metal plate and the one or two plastic plates may form a sub-assembly that is modular in that sense that the metal plate exhibits the fixed stop being assigned to a particular type or size of endoscope shaft. Moreover, a housing of the deflection control mechanism and/or a hous- ing or a body of the handpiece may be rigidly fixed to the arrangement of stacked plates by the one or more pins, bolts and/or screws. In this way stability of the support structure can be improved, and a cheap and simple design can be provided.

In case that two plastic plates are provided, the plastic plates may symmetrically enclose the base plate such that the base plate substantially is arranged in a center plane of the stack formed by the base plate and the two plastic plates. The base plane may be a center plane of the traction element being arranged substantially in a “U” shape, and may coincide with the center plane of the stack. Thus the fixed stop may be arranged in the center plane of the traction element, further improving rigidity of the mechanical stop.

In advantageous manner the at least one plastic plate forms a guideway for the longitudinal movement of the movable stop element of the at least one of the first and second coupling sections. In particular, the movable stop element may be guided in a channel an inner wall of which is formed by the at least one plastic plate. Likewise the fixation element may be guided by the plastic plate or in the same channel. In case the base plate is a metal plate, the at least one plastic plate may have a larger width than the metal plate, such that the movable stop element and/or the fixation element contacts the plastic plate only. In this way friction can be reduced that could arise in the movement of the coupling section during operation of the deflection control mechanism.

Further advantageously the movable stop element of the at least one of the first and second coupling sections may be configured as a rectangular block, the movable stop element and the guide channel having substantially rectangular cross section. The movable stop element may have a flat stop face at its proximal side, being perpendicular to the longitudinal direc- tion, for co-operating with the fixed stop of the support structure by contacting the fixed stop when the end of a range of travel has been reached. In a similar manner the fixation element may be configured as a substantially rectangular block, being guided in a correspondingly shaped channel.

In accordance with a preferred embodiment of the invention, the deflection control mecha- nism comprises a further drive wheel rotatably supported in or on the support structure, pref- erably co-axially with the aforementioned drive wheel, and a further elongate traction element having a flexible section, a first coupling section connected to a first end of the flexible section, and a second coupling section connected to a second end of the flexible section. The flexible section of the further traction element engages with the further drive wheel, and the first and second coupling sections of the further traction element each com- prise a fixation element for fixing a respective proximal end of each wire of at least one further pair of control wires, wherein at least one of the first and second coupling sections of the further traction element comprises a movable stop element co-operating with a further fixed stop of the support structure. The support structure comprises a further base plate ar- ranged approximately in a further base plane extending substantially perpendicular to a ro- tational axis of the further drive wheel, wherein the further base plate is arranged substan- tially parallel to and rigidly connected to the base plate, and wherein the further base plate supports the further fixed stop of the support structure. The further drive wheel, the further traction element, and the further base plate may be configured like the drive wheel, the trac- tion element, and the base plate described above. In particular, the deflection control mech- anism according to the present embodiment may be considered to comprise, in addition to the elements of the deflection control mechanism according to the previously described em- bodiments, further elements constituting a further deflection control mechanism, having a common support structure. The deflection control mechanism may be configured for con- trolling deflection of the steerable section of an endoscope shaft that comprises two pairs of control wires for controlling deflection of the steerable section in two different planes, a first pair of counteracting control wires being operated by rotating the drive wheel and moving the traction element as described above for controlling deflection in a first plane, and the further pair of counteracting control wires being operated by rotating the further drive wheel and moving the further traction element for controlling deflection in a second plane. The first and second planes may be at an angle of 90° to each other. Thus, the steerable section can be deflected in any arbitrary direction.

In a similar manner as described above, the further movable stop element may be adjustably connected to the fixation element of the respective coupling section of the further traction element. The flexible section and the first and second coupling sections of the further traction element may extend substantially in or adjacent to the further base plane, and the further base plate may be arranged substantially between the first and second coupling sections which may form a “U” shape. The base plate and the traction element may be considered to form a first layer of the deflection control mechanism, and the further base plate and the further traction element may be considered to form a second layer of the deflection control mechanism.

Preferably the further base plate is a metal plate, and the support structure comprises at least one further plastic plate arranged substantially parallel and adjacent to the further base plate, wherein the further base plate and the at least one further plastic plate are stacked upon one another. The at least one further plastic plate may be configured as the at least one plastic plate described above. Preferably the further base plate and the at least one further plastic plate are arranged between the first and second coupling sections, i.e. in case that the further traction element forms a “U” shape, in an inner space of the “U”. The further base plate may be substantially arranged in a center plane of the further traction element. Preferably the one or two further plastic plates are in two-dimensional contact with the base plate, resting di- rectly upon one another to improve the friction fit. The one or two further plastic plates may be fixed to the base plate by one or more pins, bolts and/or screws, for example, to increase rigidity. The at least one further plastic plate may form a guideway for the movement of the movable stop element and/or the fixation element of the at least one of the first and second coupling sections of the further traction element.

Most preferably, a stack formed by the base plate and the at least one plastic plate, being configured as described above, is stacked upon the stack formed by the further base plate and the at least one further plastic plate, wherein an intervening divider plate is arranged between both stacks. The first and the second layer may therefore be considered to be stacked upon one another forming an upper and a lower layer, respectively. The divider plate may serve to separate the guide channels of the respective traction elements of the first and second layers. The divider plate may be formed by a thin metal sheet. The arrangement of stacked plates formed by the two metal plates and the at least two plastic plates, including the divider plate, may be held together by one or more pins, bolts and/or screws. The plates may have protrusions, bores and/or cutouts to facilitate alignment and/or insertion of the one or more pins, bolts, and/or screws. In this way a particularly stable and stiff design of the deflection control mechanism can be achieved. The base plates and the at least two plastic plates can be held together to form a sub-assembly that can be manufactured beforehand, wherein only the base plates may be assigned to a particular type and size of endoscope shaft, and that can be connected precisely and rigidly to a housing or a body of the handpiece, for example.

In accordance with a preferred embodiment of the invention the support structure comprises a frame element having a plate-like shape, the frame element being arranged substantially perpendicular to the base plane, wherein the frame element has a first and a second cutout, and wherein a distal end section of the base plate is inserted into the first cutout and a distal end section of the further base plate is inserted into the second cutout. In particular, the distal end sections of the base plate and the further base plate each may be configured as a protru- sion being inserted into a respective cutout of the frame element. The protrusion may be hook-shaped, the hook seizing or clamping the frame element such that the base plate and the further base plate are fixedly connected to the frame element. Most preferably the base plate and the further base plate are held in the respective cutout of the frame element without play and perpendicular to a plane of the frame element. The base plate and the further base plate each may be held on the frame element by the hook-shaped protrusion, and the two base plates and the at least two plastic plates may form a stack of plates as described above, wherein respective distal end sides of the plastic plates abut the frame element. The stack of plates may thus be held together by the frame element, not necessarily requiring additional connecting elements such as pins, bolts and/or screws. One or more plastic plates may be clamped between the base plate and the further base plate. In this way manufacture can be facilitated, such that the stack of plates can be easily assembled by stacking the plates upon each other and inserting the distal end sections of the base planes into the respective cutouts of the frame element, and thereafter connecting the thus formed sub-assembly to a housing of the deflection control mechanism and/or to a body or a housing of the handpiece, for example. For mounting the stack of plates on a body of the handpiece fixation elements may be employed such as one or more pins, bolts and/or screws which also provide additional fixation of the plates to one another. Advantageously the first and second cutouts of the frame element are recesses arranged on opposing sides of the frame element. In particular, the cutouts are formed by rectangular recesses being cut into the plate-like frame element from an upper and a lower side of the frame element, respectively. In this way, assembly of the sub-assembly formed the stack of plates and the frame element can be further simplified.

Further preferably, the frame element has a multiplicity of bores or further cutouts for hold- ing respective sheaths of the wires of the at least two pairs of control wires. In particular, respective wire coil mountings may be inserted in the bores or cutouts, the wire coil mount- ings being configured for holding wire coils in which the respective control wires are guided. The bores or cutouts may be formed perpendicular to the base plane, such that each wire coil is held aligned with the longitudinal direction of the respective coupling section. In this way the control wires can be guided to minimize friction and wear.

Advantageously the support structure comprises a cage structure in which the drive wheel and, preferably, the further drive wheel, are rotatably supported, for example on a fixed axle, the axle being held in the cage structure. Preferably the cage structure is rigid, the axle being rigidly fixed in the cage structure. Further the support structure may comprise a housing of the deflection control mechanism, the housing being rigidly, directly or indirectly, connected to the base plate and, preferably, to the further base plate, and being rigidly connected to the cage structure or at least supported on the cage structure in the longitudinal direction. The support structure may comprise a body of the handpiece. The cage structure, the housing and/or the handpiece body may be rigidly connectable to the sub-assembly formed by the metal plates, the plastic plates, and the frame element, as described above. In this way a particularly stable and rigid connection between a bearing of the drive wheel and the fixed stop can be accomplished, further improving rigidity of the mechanical stop.

According to a further aspect of the present invention, a steerable flexible endoscope has an elongate flexible shaft comprising a steerable section that is deflectable or bendable by lon- gitudinal movement of at least one pair of counteracting control wires, wherein the flexible endoscope further comprises a deflection control mechanism configured as described above. In particular, the endoscope may comprise a handpiece connected to a proximal end of the flexible shaft, the handpiece accommodating the deflection control mechanism, wherein the proximal ends of the wires of the at least one pair of counteracting control wires are fixed in the respective fixation elements of the deflection control mechanism. Most preferably, the steerable section is deflectable in two perpendicular planes by movement of two pairs of control wires, and the deflection control mechanism is configured for operating two pairs of control wires for controlling deflection in the two perpendicular planes as described before.

In accordance with a still further aspect of the present invention, an endoscope assembly set is provided that comprises at least a first and a second elongate flexible shafts, each elongate flexible shaft comprising a steerable section that is deflectable by movement of at least one pair of counteracting control wires, the first and second elongate shafts having different per- missible ranges of longitudinal movement of the control wires. The first and second elongate shafts may have different shaft diameters, different shaft lengths, different maximal deflec- tion angles, and/or may differ in further properties, resulting in different permissible ranges of longitudinal movement of the control wires. The endoscope assembly set further com- prises a deflection control mechanism that is adapted for controlling deflection of the steer- able section of the first elongate flexible shaft, wherein the deflection control mechanism is configured as described above. Thus, the deflection control mechanism comprises a first base plate supporting a fixed stop whose longitudinal position is adapted to a permissible range of movement of the at least one pair of counteracting control wires of the first elongate shaft. The deflection control mechanism is connectable to the proximal end of the first elon- gate flexible shaft.

According to this aspect of the invention, the endoscope assembly set further comprises a second base plate supporting a fixed stop a longitudinal position of which is adapted to a permissible range of movement of the at least one pair of counteracting control wires of the second elongate shaft. The longitudinal position of the fixed stop of the second base plate thus is different from the longitudinal position of the fixed stop of the first base plate. The first base plate can be exchanged with the second base plate to adapt the deflection control mechanism for controlling deflection of the steerable section of the second elongate flexible shaft. The deflection control mechanism also is connectable to the proximal end of the sec- ond elongate flexible shaft. Preferably the endoscope assembly set comprises, in addition to the first and second base plates, further first and second base plates adapted to respective permissible ranges of movement of a further pair of control wires of the first and second flexible shafts. In this way an endoscope assembly set can be provided that permits easy re- configuring of the deflection control mechanism, thus having improved versatility and re- duced cost.

Additionally the endoscope assembly set may comprise elements of the deflection control mechanism including the second base plate, forming a sub-assembly set to be assembled to form a second deflection control mechanism that is adapted for controlling deflection of the steerable section of the second elongate flexible shaft. The sub-assembly set comprises, in particular, a drive wheel, an elongate traction element, and elements of a support structure including the second base plate. Instead of the first deflection control mechanism the endo- scope assembly set may comprise elements for assembling the first deflection control mech- anism, forming a corresponding sub-assembly set comprising the first base plate. The endo- scope assembly set may thus comprise at least two alike specimen of each element men- tioned, including at least two alike traction elements comprising the movable stop elements, except for the base plates which differ in the position of the respective fixed stop, being selected in accordance with the respective shaft.

Advantageously, the movable stop element may be adjustably connected or connectable to a respective fixation element of an elongate traction element. In this case the fixed stop may be supported by the first or second base plate at a position only roughly corresponding to a permissible range of movement of the control wires of a respective one of the flexible shafts, while fine adaptation of the respective permissible range of movement can be accomplished by adjusting the movable stop element. In this way fine adjustment during manufacturing and/or re-adjustment for service can be facilitated.

Preferably, the assembly set comprises three or more flexible shafts and a corresponding number of base plates which may differ in the position of the fixed stop to conform to the permissible range of longitudinal movement of the control wires of each respective flexible shaft. The endoscope assembly set therefore can be considered modular, as the deflection control mechanism can be adapted to an arbitrary one of the flexible shafts, while only the base plates are dedicated to a particular one of the shafts. Due to the reduced number of elements and/or an increased quantity of standardized elements of the deflection control mechanism, manufacturing stock and manufacturing planning cost can be reduced.

The present invention further relates to a method for assembling a deflection control mech- anism for a flexible endoscope, the flexible endoscope having an elongate flexible shaft comprising a steerable section that is deflectable by movement of at least one pair of coun- teracting control wires. In accordance with the method, the elongate flexible shaft of the endoscope is provided, and a deflection control mechanism is provided, the deflection con- trol mechanism being configured as described above, wherein the base plate supports a fixed stop adapted to a permissible range of movement of the at least one pair of counteracting control wires of the elongate shaft. According to the method, the deflection control mecha- nism is connected to a proximal end of the elongate flexible shaft, wherein the proximal ends of both wires of the at least one pair of counteracting push-pull wires are fixed in the respec- tive fixation elements of the first and second coupling sections of the deflection control mechanism. In a subsequent or previous step the deflection control mechanism may be cov- ered by a housing of a handpiece of the endoscope or inserted into the handpiece. Thus the flexible endoscope is easy to assemble, employing cheap and simple components.

The step of providing the deflection control mechanism may include the steps of providing the support structure including the base plate having the fixed stop, and further providing the drive wheel and the elongate traction element, wherein the support structure, the drive wheel and the elongate traction element are configured as described above, and assembling the deflection control mechanism. The support structure may include a stack of plates as described above, for example the base plate embodied as a metal plate, and at least one plastic plate stacked upon one another. The stack of plates may further comprise a divider plate, a further base plate being a further metal plate, and at least one further plastic plate. The step of assembling the deflection control mechanism may comprise the steps of stacking the plates upon one another, and connecting the stack of plates to other elements of the sup- port structure such as a handpiece body and/or a cage structure holding an axle of the drive wheel. The step of stacking the plates upon one another may include the step of inserting the respective distal end sections of the base plate and the further base plate into respective cut- outs of a frame element arranged substantially perpendicular to the base plane, thereby clamping at least one of the plastic plates between the base plate and the further base plate, by which step the stack of plates can be held together without any further connecting ele- ments forming a sub-assembly. This sub-assembly is connected to other elements of the support structure such as the handpiece body and/or the cage structure, as described before. Thus assembly of the deflection control mechanism can be further facilitated.

Before the plates are stacked upon one another, the base plate may be accordingly selected out of a multiplicity of base plates or machined such that a longitudinal position of the fixed stop is at least approximately adapted to a permissible range of longitudinal movement of the control wires of the flexible shaft; the same may pertain to the further base plate. In case that the movable stop element is adjustably connected or connectable to the fixation element of the respective coupling section of the elongate traction element, a longitudinal position of the movable stop element relative to the respective fixation element may be adjusted for fine adaptation to the permissible range of movement of the control wires. In this way a particu- larly simple and cost-efficient method for assembling a flexible endoscope can be provided.

The deflection control mechanism may comprise further features, such as a brake mechanism as disclosed in the co-pending patent application “Deflection control mechanism for a steer- able flexible endoscope, steerable flexible endoscope, and method for controlling a flexible endoscope” (internal file number P01722), and/or may comprise further details as disclosed in the co-pending patent application “Deflection control mechanism for a steerable flexible endoscope, steerable flexible endoscope, endoscope assembly set, and method for assem- bling a flexible endoscope” (internal file number P01723), both filed by the same applicant on the same day as the present application, which are hereby incorporated by reference into the present application. The features of the invention as mentioned above and as described below apply not only in the combinations mentioned but also in other combinations or alone, without leaving the scope of the present invention.

Further aspects of the present invention will be apparent from the figures and from the de- scription of a particular embodiment that follows.

Fig. 1 shows a steerable flexible endoscope in an overall view;

Fig. 2 shows a deflection control mechanism in accordance with an exemplary embodiment of the present invention;

Fig. 3 shows the deflection control mechanism as in Fig. 2, but in an enlarged, horizontal longitudinal sectional view;

Fig. 4 shows a proximal part of the deflection control mechanism of Fig. 2 in an enlarged, vertical longitudinal sectional view;

Fig. 5 shows the deflection control mechanism of Fig. 2 in an enlarged, transverse sectional view; Fig. 6 shows the arrangement of stacked plates of the deflection control mechanism of Fig. 2 in a perspective view;

Fig. 7 shows the deflection control mechanism of Fig. 2, seen from a distal direction;

Fig. 8 shows the distal side of the arrangement of stacked plates of Fig. 6 with the frame element drawn transparent; Fig. 9 shows elements of an assembly set of the deflection control mechanism of Figs. 2-9.

As shown schematically in Fig. 1, a flexible endoscope 10 typically comprises a handpiece 20 and an elongate flexible shaft 30, the handpiece 20 being attached to a proximal end of the shaft 30. The handpiece 20 has an outer housing 21 made of a plastic and/or metallic material. On a lower side of the housing 21 a first hand wheel 22 and a second hand wheel 23 are arranged for controlling a deflection of a steerable section 31 of the shaft 30, as is described below. Typically the first and the second hand wheel 22, 23 are arranged co-axi- ally, and at an exterior side of the second hand wheel 23 a knob 24 for controlling a deflection brake relating to the second hand wheel 23 is provided. Further the handpiece 20 may exhibit a multiplicity of control buttons 25 for controlling various functions of the flexible endo- scope 10, such as for controlling the imaging and/or illumination system and/or irrigation and suction pumps, for example. The handpiece 20 may be connectable to an external video unit or a video monitor via connector 26 and to an external light source via light cable 27. Moreover, an instrument port 28 may be provided for inserting endoscopic instruments to be advanced through one or more respective channels to a distal end of the shaft 30 for manipulating tissue or other objects within a cavity into which the shaft 30 can be inserted.

At its distal end the flexible shaft 30 comprises a steerable section 31. The steerable section 31 may form a distal end section of the shaft 30 or, as shown in Fig. 1, may carry a distal end cap 32 which may accommodate an imaging optics and an electronic image sensor for providing an endoscopic image of a cavity into which the shaft 30 is inserted. The image signal generated by the image sensor may be transmitted via electric cables extending through the shaft 30 and the handpiece 20 to the connector 26 for being processed and dis- played by an external video unit. The shaft 30 in total is flexible to an extent to be advanced through an endoscopic access or a hollow organ towards a cavity to be observed, being ca- pable of adapting to a curved shape of the access or the organ. The steerable section 31, on the other hand, is capable of being flexed actively by turning the hand wheels 22, 23. To this end the steerable section 31 comprises an inner structure of a multiplicity of consecutive pivoting elements 33, thus being deflectable in one or more planes. The pivoting elements 33 are covered by a flexible tube to form a smooth outer surface, the shaft 30 in total having a uniform cross-sectional shape and diameter.

For controlling the deflection of the steerable section 31 two counteracting control wires (not shown in Fig. 1) are provided extending on opposite sides within the steerable section 31, by a longitudinal movement of which the steerable section 31 can be bent to one or the other side, as indicated symbolically in Fig. 1. The control wires extend along the shaft 30 and are connected at their proximal ends to a deflection control mechanism arranged within the handpiece 20 which can be operated by a user by turning the hand wheels 22, 23 for deflect- ing the steerable section 31. In the exemplary embodiment shown, the steerable section can be bent within a first plane that corresponds to the plane of the drawing, a deflection angle being controllable by rotating the first hand wheel 22. Further, the steerable section 31 can be bent in a second plane perpendicular to the first plane and perpendicular to the plane of the drawing, a corresponding deflection angle being controllable by rotating the second hand wheel 23.

Fig. 2 shows a lower portion of a handpiece 20 of a flexible endoscope in accordance with an exemplary embodiment of the invention, wherein an upper part of the housing 21 of the handpiece 20 and an inner half-shell housing have been removed to show elements of the deflection control mechanism 29. The handpiece 20 may comprise further elements not shown in Fig. 2 (see Fig. 1). As depicted in Fig. 2, a lower part of the housing is formed by a handpiece body 40 preferably formed of metal such as stainless steel, for example. At its lateral sides the body 40 carries a seal ring 41 of an elastic seal material to form a sealed connection with the upper part of the housing (not shown in Fig. 2); thus, an interior space of the handpiece 20 accommodating the deflection control mechanism 29 is sealingly en- closed. At a lower side of the body 40 the first hand wheel 22 and the second hand wheel 23 are rotatably mounted, having a common axis of rotation. The common axis is defined by an axle 43 that is non-rotating and fixedly held in a rigid metal cage 44. The axle defines a rotation axis of a drive wheel (sprocket 59, see below) that is rotationally coupled with the second hand wheel 23, and of a further drive wheel (sprocket 69) rotationally coupled with the first hand wheel 22. A lever 42 is provided for controlling a deflection brake relating to the first hand wheel 22.

Moreover, in Fig. 2 the proximal end sections of the sheaths 35, 35’, 36, 36’ of two pairs of counteracting control wires are shown; the control wires continue to the right hand side of the drawing and extend through the shaft 30 of the endoscope to the steerable section 31 (see Fig. 1). The wire sheaths 35, 35’, 36, 36’ are each firmly held in a respective wire coil mounting 51, 51’, 61, 61’. The proximal end sections of the control wires 37, 38 protrude from the respective sheaths 35, 36. In corresponding manner the proximal end sections of respective counteracting control wires of the two pairs of control wires protrude from the respective sheaths 35’, 36’, only control wire 37’ being visible in Fig. 2. The control wires 37, 37’ are each fixed in a respective fixation element (rectangular fixation blocks 52, 52’) connected to a chain 58. The chain 58 engages with the teeth of a drive wheel (sprocket 59, see Fig. 3) and is wound around the drive wheel, enclosing an angle of 180°, thus connecting the fixation block 52 to the corresponding fixation block 52’ on the other side of the deflec- tion control mechanism. The chain 58 consists of a multiplicity of segments connected to each other by hinges, which are not shown in the figures for simplicity. Further, a stopping block 56 is provided connected to the fixation block 52 and, likewise, a stopping block 56’ connected to the fixation block 52’, the stopping blocks 56, 56’ forming movable stop ele- ments co-operating with corresponding fixed stops (see below). Further, a tensioning mech- anism may be provided, such that the control wires 37, 37’ are subjected to a pre-tension.

Thus, the chain 58 can be considered a flexible section of a traction element, engaging the drive wheel (sprocket 59). By rotation of the sprocket 59, both ends of the chain 58 and connected coupling sections formed by elements 52 and 56 and corresponding elements 52’ and 56’, respectively, are moved in opposing directions, thus effecting corresponding op- posing movement of the control wires 37, 37’. In this way deflection of the steerable section 31 of the endoscope 10 in a first plane can be controlled (see Fig. 1).

In the present example the deflection control mechanism 29 comprises two layers 50, 60, an upper layer 50 being configured for controlling the deflection of the steerable section 31 in the first plane by reciprocating longitudinal movement of the upper pair of control wires 37, 37’, and a lower layer 60 being configured for controlling a deflection of the steerable section 31 in a second plane, perpendicular to the first plane, by reciprocating movement of the lower pair of control wires (of which only control wire 38 is visible in Fig. 2). The lower layer 60 is configured in a corresponding manner as described above, such that deflection of the steerable section 31 of the endoscope 10 in a direction perpendicular to the first plane can be controlled by movement of the lower pair of control wires 38, 38’. Both layers 50, 60 comprise elements of a support structure and are stacked upon one another, being mounted on an upper side of the body 40, as is described in detail below. The upper layer 50 of the deflection control mechanism 29 is operated by turning the second hand wheel 23, while the lower layer 60 of the deflection control mechanism 29 is operated by turning the first hand wheel 22.

Fig. 3 shows a partial longitudinal sectional view with the cross section being taken approx- imately in a center plane of the upper layer 50. As depicted in Fig. 3, the fixation block 52 has a longitudinal bore 53. From a distal side a ferrule 54 is inserted into the bore 53, the ferrule 54 firmly holding the proximal end of the control wire 37. At a proximal side of the block 52 a threaded rod 55 is screwed into the proximal end of the bore 53. For simplicity, the thread formed on the substantially cylindrical surface of the rod 55 is not shown in the figures. The threaded rod 55 carries a stopping block 56 forming a movable stop element. The stopping block 56 has substantially rectangular cross section and is screwed upon the threaded rod 55, the threaded rod 55 extending through a bore of the stopping block 56. During assembly of the endoscope, a longitudinal position of the stopping block 56 with respect to the fixation block 52 can be adjusted by turning the stopping block 56, thus ad- vancing it in proximal or distal direction on the threaded rod 55. During operation of the deflection control mechanism, the rectangular block 52 is guided in a correspondingly shaped channel and thus inhibited from rotation; the stopping block 56 is guided in the same channel as the fixation block 52, such that rotation of the stopping block 56 is inhibited, and the longitudinal position of the stopping block 56 relative to the fixation block 52 is fixed. The fixation block 52’ and the adjustable stopping block 56’ relating to the other one of the upper pair of control wires 37, 37’ are configured correspondingly, as are the respective elements of the lower layer 60 (only fixation block 62, rod 65, stopping block 66, hinge 67, and chain 68 being visible in Figs. 2 and 3) relating to the lower pair of control wires 38, 38’.

Fig. 4 depicts the proximal end section of the deflection control mechanism 29 in a vertical longitudinal cross section. As can be seen in Fig. 4, the sprocket 59 of the upper layer 50 is rigidly held on an articulation shaft 46 extending to a lower side of the handpiece 20 to the second hand wheel 23 with which it is connected for being rotated by turning the hand wheel 23. Likewise a sprocket 69 of the lower layer 60 of the deflection control mechanism is fixed on a further articulation shaft 47 extending coaxially with the articulation shaft 46 into the first hand wheel 22 with which it is connected for being rotated when the hand wheel 22 is rotated. The articulation shaft 46 and thus the sprocket 59 of the upper layer 50 of the de- flection control mechanism 29 is supported by a ball bearing 48 on the rigid axle 43 fixedly held in the cage 44. The articulation shaft 47 of the lower layer 60 is held by a ball bearing 49 in a cage body 44a that is firmly connected to the cage 44. In an alternative embodiment (not shown) the articulation shafts 46, 47 may be coupled to respective electric motors, such that the sprockets 59, 69 can be motor-driven for operating the deflection control mechanism 29 in a motorized or robotic way.

As is further depicted in Fig. 4, the upper layer 50 of the deflection control mechanism com- prises a metal plate 71, an upper plastic plate 70, and a lower plastic plate 72 stacked upon one another. On top of the upper plastic plate 70 a top plate of an inner half-shell housing 45 of the deflection control mechanism 29 is arranged. The plates 70, 71, 72 are held to each other by a vertical bolt 73 and, including the housing 45, by a screw 74. The lower layer 60 is separated from the upper layer 50 by a divider plate 75 formed by a thin metal sheet. The lower layer 60 comprises a further plastic plate 76 and a further metal plate 77, which are likewise stacked upon one another and held to each other by the bolt 73 and the screw 74. Further the arrangement of stacked plates is fixed to an elevated portion 40a of the handpiece body 40 by means of the bolt 73 and the screw 74. The metal plates 71, 77 may be made of stainless steel, for example. The plates 70, 71, 72, 75, 76, 77 each contact the respective neighboring plates preferably in large areas, providing a firm friction fit, and may further have co-operating alignment features such as protrusions and/or cutouts. The arrangement of stacked plates of the upper and the lower layers 50, 60 thus forms a rigid unit, being rigidly fixed to the body 40 of the handpiece 20. Further, the cage 44 and the cage body 44a are firmly held to the body 40 by a screw 44b, and the cage 44 is also supported in a longitudinal direction by directly abutting on the housing 45, forming a rigid support structure including the cage and cage body 44, 44a, the axle 43, the stack of plates 70, 71, 72, 75, 76, 77, the body 40, and the frame element 78 (see below). As can be seen in Fig. 3, the metal plate 71 of the upper layer 50 exhibits a step or shoulder 80 protruding in a transverse direction, thus forming a fixed stop limiting the movement of the stopping block 56. Similarly, a shoulder 80’ on the opposing side of the metal plate 71 forms a fixed stop limiting movement of the stopping block 56’. As described above, the metal plate 71 is enclosed in a rigid package of plates stacked upon one another, the package being rigidly connected to the cage 44 supporting the sprocket 59, such that the shoulders 80, 80’ and the stopping blocks 56, 56’ co-operate by contacting one another to form a well- defined stop limiting the movement range of the first pair of control wires 37, 37’. The metal plate 71 forming the shoulders 80, 80’ is arranged substantially in a center plane of the stack formed by plates 70, 71, and 72. The sprocket 59, chain 58, threaded rods 55, 55’ and stop- ping blocks 56, 56’ are arranged substantially symmetrically with respect to that center plane. Thus tilting of the stopping block 56 or 56’ due to contacting the shoulder 80 or 80’, respectively, is minimized.

The arrangement of stacked plates is shown in Fig. 5 in a vertical cross section drawn per- pendicular to the longitudinal direction, cutting through the fixation blocks 52, 52’. The plates 70, 71, 72 of the upper layer 50 form an essentially rectangular block, with the fixation blocks 52, 52’ being guided on the lateral sides of the plastic plates 70, 72. The metal plate

71 has a smaller width than the plastic plates 70, 72 to avoid contact with the fixation blocks 52, 52’. Thus rotation of the fixation blocks 52, 52’ is inhibited, while the plastic plates 70,

72 provide guidance with low friction. Likewise, the stopping blocks 56, 56’ are guided by the lateral sides of the plastic plates 70, 72, thus inhibiting rotation while providing low friction. In a similar manner the fixation blocks 62, 62’ and stopping blocks of the lower layer 60 are guided at the lateral sides of the plastic plate 76 of the lower layer 60. The divider plate 75 is arranged between the upper layer 50 and the lower layer 60 to separate the channels in which the fixation blocks 52, 52’, 62, 62’ and the stopping blocks 56, 56’, 66 are guided. Preferably the fixation blocks 52, 52’, as well as the stopping blocks are made of metal, for example brass, thus further reducing friction with the plastic plates 70, 72, 76. The arrangement of stacked plates 70, 71, 72 of the upper layer 50, the intervening divider plate 75, and the plates 76, 77 of the lower layer 60 are supported on and rigidly fixed to an elevated portion 40a of the body 40 of the housing 21. Fig. 6 shows, in an oblique view, the stacked arrangement of plates 70, 71, 72, 75, 76, 77. On a proximal side, at least the plates 70, 72, 75, and 76 each exhibit a recess for accommo- dating the sprockets 59, 69 and/or the shafts 46, 47. On a distal side, the metal plates 71, 77 forming the base plates of the upper and the lower layer 50, 60, respectively, are held in a frame element 78. The frame element 78 has a plate-like shape and is arranged substantially perpendicular to the plates 71, 77. As is described in detail below, the frame element 78 exhibits first and second cutouts or, referring to the orientation of the frame element 78 as depicted in the figures, upper and lower cutouts 81, 82 into which distal end sections (hooks 71a, 77a) of the metal plates 71, 77 are inserted. Further, the frame element 78 has lateral cutouts 83, 83’, 84, 84’ in which the wire coil mountings 51, 51 ’, 61, 61 ’ are held. The frame element 78 may be made of stainless steel, for example. The stack of plates 70, 71, 72, 75, 76, 77 may form a pre-mounted sub-assembly, the metal plates 71, 77 exhibiting the fixed stops being adapted to the flexible shaft 30.

In Figs. 7 and 8 the distal end of the arrangement of stacked plates of Fig. 6 is shown as seen from a substantially distal direction depicting a distal side of the frame element 78. In Fig. 7 the control wires 37, 37’, 38, 38’ and wire coils 35, 35’, 36, 36’ of a flexible shaft connected to the deflection control mechanism are also shown. Fig. 8 shows the distal side of the frame element 78 in a perspective view, wherein the frame element 78 is drawn transparent.

As can be seen in Figs. 7 and 8, an upper cutout 81 is cut into an upper side of the frame element 78, being configured as a substantially rectangular recess. A distal end section of the metal plate 71 of the upper layer 50 is configured as a hook 71a extending in a distal and in a lateral direction. The hook 71a is inserted into the upper cutout 81 of the frame element 78 such that the metal plate 71 is held to the frame element 78. Similarly, a distal end section of the metal plate 77 of the lower layer 60 forms a hook 77a being inserted into a substan- tially rectangular lower cutout 82 cut into a lower side of the frame element 78 such that the metal plate 77 is held to the frame element 78. The plastic plates 70, 72, 76, as well as the intervening divider plate 75, contact the proximal side of the frame element 78 with their respective distal end faces. The metal plates 71, 77, the plastic plates 70, 72, 76, and the divider plate 75 are stacked upon one another forming a stack of plates, wherein the plates 72, 75, and 76 are sandwiched between the metal plates 71, 77 and held due to a clamping force exerted by the frame element 78. The stack of plates is further held together by at least one bolt 73 and by screws 74, 85.

The metal plate 77 of the lower layer 60 rests on an elevated portion 40a of the body 40. The stack of plates 70, 71, 72, 75, 76, 77 is fixed to the body 40 by bolt 73 and screws 74, 85. The elevated portion 40a is formed on a step portion 40b, which in turn is provided on a reinforcement portion 40c of the body 40. The reinforcement portion 40c serves to improve stiffness of the body 40 and the stack of plates 70, 71, 72, 75, 76, 77. The reinforcement portion 40c is cut out in a distal section of the body 40 and is recessed on lateral sides of the step portion 40b in a further section of the body 40, as can be seen in Fig. 5.

The frame element 78 further exhibits lateral cutouts 83, 83’, 84, 84’ being formed by sub- stantially semi-circular recesses cut into the lateral sides of the frame element 78 (see Fig. 6). The wire coil mountings 51, 51’, 61, 61’ each have a rectangular proximal end piece 51a, 51a’, 61a, 61a’ and a rectangular distal end piece 51b, 51b’, 61b, 61b’, connected by a cy- lindrical sleeve 51c, 51c’, 61c, 61c’ (see Fig. 8). The cylindrical sleeves 51c, 51c’, 61c, 61c’ of the wire coil mountings 51, 51’, 61, 61’ are inserted into a respective one of the lateral cutouts 83, 83’, 84, 84’, such that the wire coil mountings 51, 51’, 61, 61’ are fixed to the frame element 78 and thereby fixed to the stack of plates 70, 71, 72, 75, 76, 77. The wire coils 35, 35’, 36, 36’ of the flexible shaft 30 can be inserted into the proximal end pieces 51a, 51a’, 61a, 61a’ and/or into the cylindrical sleeves 51c, 51c’, 61c, 61c’ such that the control wires 37, 37’, 38, 38’ continue in a proximal direction to be fixed in the fixation blocks 52, 52’, 62, 62’.

The semi-circular recesses forming the lateral cutouts 83, 83’, 84, 84’ are machined such that their respective axes are aligned with the proximal end sections of a respective one of the wire coils 35, 35’, 36, 36’ and the respective control wires 37, 37’, 38, 38’ to avoid kinking of the control wires 37, 37’, 38, 38’ and to minimize wear. The rectangular proximal end pieces 51a, 51a’ of the wire coil mountings 51, 51’ contact, with a respective side sur- face, the corresponding lateral side surfaces of the plastic plates 70, 72, such that rotation of the wire coil mountings 51, 51’ is inhibited. Similarly in order to avoid rotation, the rectan- gular proximal end pieces 61a, 61a’ of the wire coil mountings 61, 61’ of the lower layer 60 abut, with their respective side surfaces, the lateral side surfaces of the plastic plate 70 and, preferably, the elevated portion 40a of the body 40.

The metal plates 71, 77, the plastic plates 70, 72, 76, and the divider plate 75 are depicted individually in Fig. 9. Further, Fig. 9 shows two bolts 73 and the frame element 78. As can be seen in Fig. 9, the metal plates 71, 77 forming the base plates of the upper and the lower layer 50, 60, respectively, are configured basically alike; however the metal plate 71 has shoulders 80, 80’ at a first longitudinal position, and the metal plate 77 has shoulders 90, 90’ formed at a slightly different longitudinal position to co-operate with the stopping blocks 66 of the lower layer 60 to limit a range of movement of control wires 38, 38’ correspondingly. Further the plastic plates 70, 72, 76 are configured alike or almost alike.

In order to assemble a flexible endoscope 10, in accordance to an exemplary method, a de- flection control mechanism 29 and a flexible shaft 30 are provided. For assembling the de- flection control mechanism 29 the metal plates 71, 77, the plastic plates 70, 72, 76, the di- vider plate 75, the frame element 78, and one or more bolts 73 are provided, as depicted in Fig. 9. The metal plates 71, 77 are accordingly machined, or may be selected out of a multi- plicity of metal plates formed alike except for a longitudinal position of the shoulders 80, 80’, 90, 90’, in accordance with a permissible range of longitudinal movement of the control wires 37, 37’, 38, 38’ of the flexible shaft 30 to which the deflection control mechanism 29 is adapted for controlling deflection of the steerable section 31. Further, a body 40, screws 74, 85, and the further elements of the deflection control mechanism 29 as described above are provided.

The plates 70, 71, 72, 75, 76, and 77 are stacked upon one another, and the distal end sections (hooks 71a, 77a) of the metal plates 71, 77 are inserted into the cutouts 81, 82 of the frame element 78, thus the plates 72, 75, 76 being clamped between the metal plates 71, 77. Stack- ing and alignment of plates 70, 71, 72, 75, 76, and 77 may be aided by alignment features such as protrusions and/or cutouts of the plates. The sub-assembly formed by the stack of plates 70, 71, 72, 75, 76, 77 is thus held together by the frame element 78. The stack may further be stabilized by inserting the one or more bolts 73 into respective bores.

Thereafter the stack of plates 70, 71, 72, 75, 76, 77 is placed on the elevated portion 40a of the body 40 and fixed on the body 40 by screws 74, 85. The wire coil mountings 51, 51’, 61, 61’ are inserted with their sleeves 51c, 51c’, 61c, 61c’ into a respective one of the lateral cutouts 83, 83’, 84, 84’. Further, the above mentioned further elements of the support struc- ture are mounted, the drive wheels (sprockets 59, 69) are mounted, and the elongate traction elements are engaged with the drive wheels to assemble the deflection control mechanism configured as described above.

In case that the longitudinal position of the shoulders 80, 80’, 90, 90’ of the metal plates 71, 77 is adapted exactly, or with sufficient accuracy, to the permissible range of movement of the control wires 37, 37’, 38, 38’ of the flexible shaft 30, no further steps of adjustment of the deflection control mechanism 29 are required. On the other hand, if the longitudinal po- sition of the shoulders 80, 80’, 90, 90’ of the metal plates 71, 77 is only approximately, and not with sufficient accuracy, adapted to the permissible range of movement of the control wires 37, 37’, 38, 38’, the stopping blocks 56, 56’, 66 may be turned on the respective threaded rod 55, 55’, 65, 65’ for finely adjusting the limit of movement of the respective control wire 37, 37’, 38, 38’. To this end the assembly of stacked plates 70, 71, 72, 75, 76, 77 may be partially dismantled, or the stopping blocks 56, 56’, 66 laterally pulled out of a respective guide channel. After adjustment, the stack of plates 70, 71, 72, 75, 76, 77 is fixed again, as described, or the stopping blocks 56, 56’, 66 re-inserted into the respective guide channel. Finally, a half-shell inner housing 45 may be mounted covering the deflection con- trol mechanism on an upper and on lateral sides. Thus the deflection control mechanism is easy to assemble and to adapt to a particular flexible shaft 30, employing cheap and simple components.

The deflection control mechanism is connected to a proximal end of the elongate flexible shaft 30, wherein the proximal ends of the wire coils 35, 35’, 36, 36’ are mounted in the wire coil mountings 51, 51’, 52, 52’, and the proximal ends of the control wires 37, 37’, 38, 38’ are fixed in the respective fixation blocks 52, 52’, 62, 62’. In a subsequent or previous step the deflection control mechanism 29 may be covered by a housing of a handpiece 20 of the endoscope 10 or inserted into the handpiece 20.

In the above description the terms “upper” and “lower” relate to the orientation of the hand- piece 20 and the deflection control mechanism 29 as shown in the figures. Any other orien- tation may be chosen by a user, according to requirements during use.

For clarity not all reference numerals are displayed in all figures. If a reference numeral is not explicitly mentioned in the description of a figure, it has the same meaning as in the other figures.

Reference numerals

10 Flexible endoscope 20 Handpiece 21 Housing

22 Hand wheel

23 Hand wheel

24 Knob

25 Button 26 Connector

27 Light cable

28 Instrument port

29 Deflection control mechanism

30 Shaft 31 Steerable section

32 End cap

33 Pivoting element 35, 35’ Sheath

36, 36’ Sheath 37, 37’ Control wire

38, 38’ Control wire

40 Body

40a Elevated portion 40b Step portion

40c Reinforcement portion

41 Seal ring

42 Lever

43 Axle 44 Cage

44a Cage body

44b Screw

45 Half-shell housing

46 Shaft 47 Shaft

48 Ball bearing

49 Ball bearing

50 Upper layer

51, 51’ Wire coil mounting 51a, 51a’ Proximal end piece

51b, 51b’ Distal end piece

51c, 51c’ Sleeve

52, 52’ Block 53, 53’ Bore

54, 54’ Ferrule

55, 55’ Rod

56, 56’ Block

57, 57’ Hinge 58 Chain

59 Sprocket

60 Lower layer

61, 61’ Wire coil mounting

61a, 61a’ Proximal end piece 61b, 61b’ Distal end piece

61c, 61c’ Sleeve

62, 62’ Block

65 Rod

66 Block 7 Hinge

68 Chain

69 Sprocket

70 Plastic plate 71 Metal plate

71a Hook

72 Plastic plate

73 Bolt

74 Screw 75 Divider plate

76 Plastic plate

77 Metal plate

77 a Hook

78 Frame element 80, 80’ Shoulder

81 Cutout

82 Cutout

83, 83’ Cutout

84, 84’ Cutout 85 Screw 90, 90' Shoulder

Claims

1. Deflection control mechanism for a steerable flexible endoscope (10), the endoscope (10) having an elongate flexible shaft (30) comprising a steerable section (31) that is deflectable by movement of at least one pair of counteracting control wires (37, 37’, 38, 38’), the deflection control mechanism (29) comprising a support structure, a drive wheel rotatably supported in or on the support structure, and an elongate traction ele- ment having a flexible section, a first coupling section connected to a first end of the flexible section, and a second coupling section connected to a second end of the flexi- ble section, wherein the flexible section of the traction element engages with the drive wheel, wherein the first and second coupling sections each comprise a fixation element for fixing a respective proximal end of each wire of the at least one pair of control wires (37, 37’, 38, 38’), and wherein at least one of the first and second coupling sec- tions comprises a movable stop element co-operating with a fixed stop of the support structure, characterized in that the support structure comprises at least one base plate arranged substantially in a base plane extending at least approximately perpendicular to a rotational axis of the drive wheel, wherein the base plate supports the fixed stop.

2. Deflection control mechanism according to claim 1, characterized in that the movable stop element is adjustably connected to the fixation element of the respective coupling section.

3. Deflection control mechanism according to claim 1 or 2, characterized in that the flexible section and the first and second coupling sections of the traction element ex- tend substantially in or adjacent to the base plane and that the base plate is arranged substantially between the first and second coupling sections.

4. Deflection control mechanism according to any one of claims 1-3, characterized in that the base plate is a metal plate (71, 77) and that the support structure comprises at least one plastic plate (70, 72, 76) arranged substantially parallel and adjacent to the base plate, the metal plate (71, 77) and the at least one plastic plate (70, 72, 76) being stacked upon one another.

5. Deflection control mechanism according to claim 4, characterized in that the at least one plastic plate (70, 72, 76) forms a guideway for the movement of the movable stop element and/or the fixation element of the at least one of the first and second coupling sections.

6. Deflection control mechanism according to any one of the preceding claims, charac- terized in that the deflection control mechanism comprises a further drive wheel rotat- ably supported in or on the support structure, and a further elongate traction element having a flexible section, a first coupling section connected to a first end of the flexible section, and a second coupling section connected to a second end of the flexible sec- tion, wherein the flexible section of the further traction element engages with the fur- ther drive wheel, wherein the first and second coupling sections of the further traction element each comprise a fixation element for fixing a respective proximal end of each wire of at least one further pair of control wires (38, 38’), wherein at least one of the first and second coupling sections of the further traction element comprises a movable stop element co-operating with a further fixed stop of the support structure, wherein the support structure comprises a further base plate arranged approximately in a further base plane extending substantially perpendicular to a rotational axis of the further drive wheel, wherein the further base plate is arranged substantially parallel to and rigidly connected to the base plate, and wherein the further base plate supports the further fixed stop.

7. Deflection control mechanism according to claim 6, characterized in that the further base plate is a metal plate (77) and that the support structure comprises at least one fur- ther plastic plate (76) arranged substantially parallel and adjacent to the further base plate, the further base plate and the at least one further plastic plate (76) being stacked upon one another.

8. Deflection control mechanism according to claim 7 in combination with claim 4, char- acterized in that a stack formed by the metal plate (71) and the at least one plastic plate (70, 72) is stacked upon a stack formed by the further metal plate (77) and the at least one further plastic plate (76), wherein a divider plate (75) is arranged between both stacks.

9. Deflection control mechanism according to any one of claims 6-8, characterized in that the support structure comprises a frame element (78) arranged substantially per- pendicular to the base plane, wherein the frame element (78) has first and second cut- outs (81, 82) into which respective distal end sections of the base plate and the further base plate are inserted.

10. Deflection control mechanism according to claim 9, characterized in that the cutouts (81, 82) of the frame element are recesses formed on opposing sides of the frame ele- ment (78).

11. Deflection control mechanism according to claim 9 or 10, characterized in that the frame element has a multiplicity of bores or further cutouts (83, 83’, 84, 84’) for hold- ing respective sheaths of the control wires (37, 37’, 38, 38’).

12. Deflection control mechanism according to any one of the preceding claims, charac- terized in that the support structure further comprises a cage structure in which the drive wheel is rotatably supported, and a housing (45) and/or a handpiece body (40) connected to the cage structure, the housing (45) and/or the handpiece body (40) being rigidly connected to the base plate.

13. Steerable flexible endoscope having an elongate flexible shaft (30) comprising a steer- able section (31) that is deflectable by movement of at least one pair of counteracting control wires (37, 37’, 38, 38’), further comprising a deflection control mechanism (29) in accordance with any one of the preceding claims.

14. Endoscope assembly set, comprising at least a first and a second elongate flexible shafts (30), each elongate flexible shaft (30) comprising a steerable section (31) that is deflectable by movement of at least one pair of counteracting control wires (37, 37’, 38, 38’), the first and second elongate shafts (30) having different permissible ranges of longitudinal movement of the control wires (37, 37’, 38, 38’), the endoscope assembly set further comprising a deflection control mechanism (29) adapted for controlling de- flection of the steerable section (31) of the first elongate flexible shaft (30), the deflec- tion control mechanism (29) being configured in accordance with any one of claims 1- 12, wherein the deflection control mechanism (29) comprises a first base plate support- ing a fixed stop adapted to a permissible range of movement of the at least one pair of counteracting control wires (37, 37’, 38, 38’) of the first elongate shaft (30), wherein the endoscope assembly set further comprises a second base plate supporting a fixed stop adapted to a permissible range of movement of the at least one pair of counteract- ing control wires (37, 37’, 38, 38’) of the second elongate shaft (30), the first base plate being exchangeable by the second base plate to adapt the deflection control mechanism (29) for controlling deflection of the steerable section (31) of the second elongate flex- ible shaft (30).

15. Method for assembling a flexible endoscope (10), the flexible endoscope (10) having an elongate flexible shaft (30) comprising a steerable section (31) that is deflectable by movement of at least one pair of counteracting control wires (37, 37’, 38, 38’), wherein the elongate flexible shaft (30) is provided, a deflection control mechanism (29) is pro- vided, the deflection control mechanism (29) being configured in accordance with any one of claims 1-12, wherein the base plate supports a fixed stop adapted to a permissi- ble range of movement of the at least one pair of counteracting control wires (37, 37’, 38, 38’) of the elongate shaft (30), and the deflection control mechanism (29) is con- nected to a proximal end of the elongate flexible shaft (30).