Abstract:
An exchangeable tool assembly is provided for an endoscopic treatment device, comprising a flexible shaft connected at its distal end to a tool unit and at its proximal end to a coupling element for coupling the tool assembly to a motor of the treatment device. The flexible shaft transmits a rotary movement of the motor to the tool unit. The flexible shaft is connected to said tool unit such that said flexible shaft and said tool unit form a jointly exchangeable unit. Further, a locking mechanism for releasably holding said tool assembly at said treatment device comprises a locking element arranged at said tool unit and a locking member arranged at said treatment device which is engageable in said locking member to releasably hold said unit formed by said tool unit and said flexible shaft at the treatment device, which can be withdrawn as a whole after this engagement of said locking member from said locking element.

Description:
CROSS-REFERENCE OF PENDING APPLICATIONS 
     This application claims priority of German application 10023685.5 filed May 16, 2000 and European application 00119988.4 filed Sep. 14, 2000, both applications are pending. 
     BACKGROUND OF THE INVENTION 
     The invention relates to an exchangeable tool assembly for an endoscopic treatment device, comprising a flexible shaft connected at its distal end to a tool unit and at its proximal end to a coupling element, and further comprising a locking mechanism to releasably hold the tool assembly at the treatment device. 
     Further, the invention relates to an endoscopic treatment device with an afore-mentioned tool assembly. 
     A tool assembly and a treatment device of the afore-mentioned kind are known from U.S. Pat. No. 5,349,940. 
     Such an endoscopic treatment device can be used in technical applications, in the medical field, in particular in the field of minimally invasive surgery, and also in dental medicine or dental techniques. 
     In technical applications a treatment carried out with the treatment device includes, for example, removing burrs from forged pieces, grinding notches in turbine blades, grinding off corrosion for surface analysis, for example crack testing, grinding off welding seams, boring holes, etc. In minimally invasive surgery such a treatment device can be used to treat tissue in the body through a small incision, for example for excising tissue. 
     In general such an endoscopic treatment device is intended to be used for universal endoscopic treatments and/or analysis under visual control, mainly with a rotating tool, at difficultly accessible locations. 
     In known rigid devices, the transmission of motion from the proximally located motor to the distally located working tool is accomplished with a rigid drive shaft or with transmission belts. These transmission belts require gears and deflection rollers, which lead to losses in space and efficiency. The construction of the power transmission from the proximal motor to the distal working unit is complicated and subject to disturbance. Rigid drive shafts lying parallel and close to the longitudinal axis of the working shaft cannot be coupled directly to the motor, because the motor has certain minimal dimensions which obstruct the fixed optic lenses. However, this would not be the case with fiber optics, which, however, has less resolution. 
     Flywheel forces and imbalances, which can occur in use of the endoscopic treatment device at the tool unit and at the transmission element in form of the flexible shaft lead to vibrations which cause an upper limit to the rotary speed. The lower speeds resulting from this construction lead to a reduction in removal or excising capacity. 
     Furthermore, it is not only the distally located tool unit which is subject to wear in such a treatment device, but also the flexible shaft and the coupling of the flexible shaft to the motor. Treatment devices are known, where the tool unit and the flexible shaft and the coupling element cannot be exchanged or at least not simply, as it is, for example, the case with the tool assembly known from U.S. Pat. No. 5,349,940, whereby maintenance of such treatment devices is very cost intensive. 
     Medical devices are known which must be operated with flushing fluid to lubricate the bearings. Such a treatment device is therefore not usable in technical applications. The exchangeable tool assembly contains all of the wearing elements such as bearings, the working head as well as the shaft and shaft protector. However, it is rigid and due to its construction it is not designed for higher rotary speeds. 
     From the document U.S. Pat. No. 5,349,940 mentioned at the outset an endoscopic treatment device is known, comprising an exchangeable tool assembly, wherein the tool assembly comprises a flexible shaft, which is connected at its distal end to a tool unit and at its proximal end to a coupling element. The tool unit comprising the working head, for example a milling head, is releasably connected to the flexible shaft via a screw and plug coupling so that the coupling between the tool unit and the shaft must be released at first in order to exchange the tool unit. The flexible shaft itself comprises a plurality of parts and exchange and mounting of the shaft to the device is difficult. The connection between the tool unit, the flexible shaft and the motor therefore consists of a plurality of parts, i.e. several single parts must be fitted, plugged and screwed together, whereby the exchange of this known exchangeable tool assembly and, thus, the maintenance of the treatment device is complicated. 
     It is, therefore, an object of the present invention to improve an exchangeable tool assembly for an endoscopic treatment device mentioned at the outset as well as to provide such a treatment device, such that the tool assembly can be simply and quickly exchanged, wherein all parts subject to wear are exchangeable with low expenditure of handling. 
     SUMMARY OF THE INVENTION 
     According to the present invention, this object is achieved with an exchangeable tool assembly for an endoscopic treatment device, comprising: 
     a tool unit; 
     a coupling element for coupling said tool assembly to a motor of said treatment device; 
     a flexible shaft having a distal end and a proximal end, said distal end being connected to said tool unit and said proximal end being connected to said coupling element, said flexible shaft transmitting a rotary movement of said motor to said tool unit, said flexible shaft being connected to said tool unit such that said flexible shaft and said tool unit form a jointly exchangeable unit; and 
     a locking mechanism for releasably holding said tool assembly at said treatment device, said locking mechanism comprising a locking element arranged at said tool unit and a locking member arranged at said treatment device, which is engageable with said locking element to releasably hold said jointly exchangeable unit formed by said tool unit and said flexible shaft, which can be withdrawn as a whole after disengagement of said locking member from said locking element. 
     Further, according to the present invention, an endoscopic treatment device is provided with an exchangeable tool assembly according to the present invention. 
     The afore-mentioned connection between the tool unit and the flexible shaft is advantageous as to a simple exchange of the exchangeable tool assembly, because these two elements subject to wear can be exchanged as an integral unit and thus in an easily handable manner, because they have not to be connected to one another for exchange. Furthermore, this configuration advantageously makes it possible to configure the tool unit and the flexible shaft in miniaturized form, whereby very high rotary speeds of the tool assembly are possible, without vibrational dampening measures, such as dynamic balancing, dampening and friction-reducing measures being additionally necessary. Such a miniaturization cannot be envisaged with the exchangeable tool assembly known from U.S. Pat. No. 5,349,940 because of its constitution of multiple parts. According to the present invention, the locking mechanism is configured such that locking of the tool assembly, i.e. the integral unit consisting of the tool unit and the flexible shaft, can be accomplished by means of a locking element arranged at the tool unit, in which a locking member of the treatment device engages. The flexible shaft is then axially immobilized at the treatment device through the locking of the tool unit. 
     The connection between the flexible shaft and the tool unit can be realized by assembling, for example by soldering or welding, or the tool unit can be connected to the flexible shaft in one piece or in monolithic fashion. 
     In a preferred embodiment the flexible shaft is connected to the proximal coupling element such that the coupling element can be withdrawn together with the flexible shaft and the tool unit after releasing the locking mechanism. 
     In this embodiment the tool unit, the flexible shaft as well as the coupling element and thus all parts subject to wear are exchangeable in simply handable manner, and for immobilizing this unit at the treatment device only the afore-mentioned locking mechanism comprising the locking element arranged at the tool unit and the locking member arranged at the treatment device is to be manipulated. 
     The locking mechanism according to the present invention having a locking member of the treatment device engageable into a locking element of the tool unit represents a quickly releasable and quickly lockable locking mechanism, which essentially simplifies the exchange of the exchangeable tool assembly. As already mentioned all parts subject to wear are integrated in one exchangeable element, whereby handling of the exchange is simplified and furthermore, the costs of the exchangeable tool assembly are reduced with respect to the manufacturing expenditure. 
     In a further preferred embodiment the tool unit comprises a working head and a tool shaft, and said locking element is configured as an annular groove in that tool shaft. 
     When the working head and the tool shaft rotate, the locking member engaging in the groove axially secures the exchangeable tool assembly. The advantages of this measure are that a constructively very simple locking mechanism is achieved, which can be realized in a simple production operation, namely by machining the circumferential annular groove at the tool shaft. Such a locking mechanism has the further advantage that locking is achieved with a minimal requirement on additional shaft diameter. By locking the tool assembly in its distal region, namely at the tool unit, a good tool guidance with the flexible shaft is made possible. If the tool assembly were locked proximally at the motor coupling, the tool unit when subjected to axial force would be deflected proximally due to the spring action of the flexible shaft. Thereby, handling of the tool would be rendered inaccurate. 
     In a further preferred embodiment a bearing bush is provided which receives an axial portion of the tool shaft and has a slot configured such that the locking element can pass through the slot. 
     This measure has the advantage that the rotating tool and the bearing bush are simultaneously locked by the locking mechanism. The bearing bush can be withdrawn from the treating device when the tool assembly is withdrawn, and can be exchanged as a part subject to wear. As will be described later on the bearing bush has a slight radial play in the treatment device. 
     In a further preferred embodiment the flexible shaft is configured as a braided cable, or as a profile in form of a wire, tube or angular profile. 
     These measures represent advantageous configurations of the flexible shaft, in order to impart a certain flexibility thereto. With a flexible shaft, the tool assembly can be also used in such treatment devices, which comprise a flexible working shaft in order to reach difficultly accessible working areas. With a configuration of the flexible shaft as a hollow profile, the shaft can also be used for transportation of material, signals or information to the working head of the tool unit and therefrom. 
     In a further preferred embodiment the flexible shaft is made from a highly flexible alloy. 
     Such highly flexible alloys can be Nitinol® or Tinel®. 
     In a further preferred embodiment a spiral is provided which rotatably receives an axial portion of the flexible shaft. 
     With the spiral surrounding the flexible shaft, with a play least possible and not rotating therewith, a stabilizing rigidity can be given to the flexible shaft despite its flexibility, and imbalances cannot build up. Imbalance would lead to disturbing vibrations and to frictional losses on the inner side of the spiral. 
     In this context it is preferred if a mantle, preferably a plastic mantle is provided surrounding the spiral. 
     The plastic mantle advantageously serves as a vibration damper. Resonance are eliminated by damping which when combining the vibrations could lead to frictional losses. Furthermore, the plastic mantle advantageously protects the spiral against deformations which could arise in assembly or disassembly. Furthermore, it prevents lubricant loss. 
     A treatment device according to the present invention comprises a tool assembly according to the present invention according to one or more of the afore-mentioned embodiments. 
     In this context, it is preferred, when the locking member extends perpendicularly to a longitudinal axis of the device and at its end opposite to the longitudinal axis is attached to a holding part of the locking mechanism running parallel to the longitudinal axis. 
     Further, it is preferred, if the holding part is configured as a biased bracket urged substantially perpendicularly to the longitudinal axis, so that the locking member is movable perpendicularly to the longitudinal axis. 
     This configuration of the locking mechanism having the locking member arranged at the holding part configured as an elastically biased bracket has the advantage that locking as well as releasing is very easy to handle, in particular, the locking member automatically disengages from the locking element at the tool unit on release of the locking mechanism. 
     In this context, it is further preferred if the locking mechanism comprises a sleeve displaceable in axial direction, which is configured to be slideable over the bracket and moves the locking member perpendicularly to the longitudinal axis, so that the locking member engages in the locking element of the tool assembly. 
     Altogether, the locking mechanism according to the present invention has the advantage that no screws have to be tightened or to be released for exchanging the tool assembly, but only the slide sleeve must be displaced in proximal direction whereby the biased bracket with the locking member arranged thereon automatically resiliently moves aside, whereby the locking member disengages from the locking element, and must be displaced in distal direction for locking, whereby the slide sleeve urges the bracket radially inwardly so that the locking member engages the locking element. 
     In a further preferred embodiment an insert channel is provided which receives the tool assembly, wherein the tool assembly can be introduced into and removed from the insert channel in axial direction, and wherein the tool assembly is received in the insert channel with radial play. 
     This play has the advantageous effect that imbalances of the tool unit do not have a strong effect. In the region of the bearing bush this measure has the effect that imbalances do not have a strong effect, but are compensated by a minimal movement of the bearing bush. This self-balancing increases the lifetime, because the vibrations caused by friction are minimized. In the region of the flexible shaft this play also has the advantage that the shaft is slightly moved by the imbalances whereby a self-balancing arises which minimizes the vibrations. 
     In a further preferred embodiment the treatment device comprises a working shaft, in which the insert channel and parallelly thereto a channel for an endoscope is arranged. 
     In a further preferred embodiment the working shaft comprises in its distal region a flexible part for deflecting the tool unit with respect to a longitudinal axis portion of a proximal region of the working shaft. 
     By this measure difficultly accessible working regions can be endoscopically treated or analyzed, and the motor rotation can be transmitted through the bend to the tool unit via the flexible shaft. 
     Further advantages will be apparent from the following description and the attached drawings. 
     It is to be understood that the features mentioned above and those yet to be explained below can be used not only in the respective combinations indicated, but also in other combinations or in isolation, without leaving the context of the present invention. 
     The invention will be explained and described in more detail below with reference to selected exemplifying embodiments in conjunction with the attended drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 a  shows a longitudinal sectional view of a working shaft of a treatment device with an exchangable tool assembly in its state locked at the treatment device; 
     FIG. 1 b  shows a representation similar to FIG. 1 a ) showing the tool assembly in a state released from the treatment device; 
     FIG. 2 shows a side view of the exchangeable tool assembly in FIG. 1, partially in longitudinal sectional representation, withdrawn from the treatment device in a curved state; 
     FIG. 3 shows a side view of an endoscopic treatment device having a rigid working shaft; and 
     FIG. 4 shows a side view of an endoscopic treatment device having a flexible working shaft. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     With reference to FIGS. 1 and 2 an exchangeable tool assembly  10  is described hereafter, which is used in an endoscopic treatment device according to FIGS. 3 and 4 to be discussed below. 
     In FIG. 1, the exchangeable tool assembly  10  is shown in a state inserted in a treatment device, and is shown alone and in a curved state compared with FIG. 1 in FIG.  2 . 
     The exchangeable tool assembly  10  and the endoscopic treatment devices to be discussed below can be used in technical applications, medical applications, in particular in the minimally invasive surgery or in the dental medicine or dental techniques as well. 
     The cost effectively produceable tool assembly  10  in a realized embodiment comprises a tool unit  12 , which comprises a working head  14 , for example a grinder, miller, etc. and a tool shaft  16 , for example for use in dental technology. 
     At the proximal end of the tool shaft  16  a flexible shaft  18  in form of a braided cable made of steel is connected to the tool unit  12 , for example by means of a soldering  30 , and forms with the tool unit  12  an integrated unit. On one hand the braided cable is more flexible than a solid wire, while on the other hand the braided cable dampens crossvibrations arising from an imbalance. 
     The tool unit  12  is proximally connected to a coupling element  20  via the shaft  18  as to form an integrated unit therewith, in that the shaft  18  is connected with its proximal end by means of a soldering  32  for example, to the coupling element  20 . The coupling element  20  forms the releasable connection of the tool assembly  10  to a motor  22 , exactly spoken to the motor shaft  24  thereof. 
     The tool unit  12 , the shaft  18  and the coupling element  20  form a jointly exchangeable integral unit, which can be instead of being soldered together be made in one piece. 
     The shaft  18  is surrounded by a non-rotating spiral  26 . Between the spiral  26  and the shaft  18  is provided the smallest possible play so that no imbalance can build up. An imbalance would lead to disturbing vibrations and also to frictional losses on the inner side of the spiral  26 . The spiral  26  itself is surrounded by a mantle, in particular a plastic mantle  28  in form of a shrink tube, which has several functions. Firstly, it serves as a vibration damper. Resonances are eliminated by the damping which when combining the vibrations could lead to frictional losses. Secondly, it protects the spiral  26  against deformations, which could arise in assembly or disassembly. Thirdly, it prevents lubricant loss. 
     The tool assembly  10  is disposed in an insert channel  34  of a treatment device, like that represented in FIGS. 3 or  4 , for example. The tool assembly  10  is received in the insert channel  34  with play. 
     The tool shaft  16  of the tool unit  12  is partially surrounded by a bearing bush  38 . At the proximal side of the tool shaft  16  a holding disc  40  is fixed to the shaft  18 , for example, by solderings  42 . The holding disc  40  secures the bearing bush  38  against a sliding relative to the tool unit  12 , in particular when the tool assembly  10  is removed from the treatment device, because, without the holding disc  40 , the bearing bush  38  could get stuck in the distal end of the insert channel  34 . 
     The bearing bush  38  is non-rotating. 
     In the distal region of the insert channel  34  a locking mechanism  44  is provided, anchoring the bearing bush  38  and therefore the entire exchangeable tool assembly  10 . In the embodiment shown in FIG. 1 the locking mechanism  44  comprises a slide sleeve  46  in the distal region of the treatment device, which is disposed about the working shaft  36  of the treatment device. The slide sleeve  46  can be shifted in axial direction distally, as represented in FIG. 1 a , and proximally, as represented in FIG. 1 b . In the distally displaced position (FIG. 1 a ) the slide sleeve  46  locks the tool unit  12  having a locking element  52  in form of an annular circumferential groove therein, by urging an outwardly biased bracket to the inside, which has a locking member  50 , and thereby axially immobilizes the tool unit  12 , the shaft  18  and the coupling element  20  at the treatment device. The locking member  50  is configured in form of a tappet fixed to the bracket  48 , which engages the groove forming the locking element  52  in the distal position of the slide sleeve  46 , whereby the tool assembly  10  is axially immobilized at the treatment device. The locking mechanism  44  achieves locking with a minimal requirement on additional shaft diameter of the treatment device. The rotating tool unit  12  and the bearing bush  38  are axially locked simultaneously, the latter having a slot  53  therein, through which the tappet passes and engages in the annular groove of the tool shaft  16  for the purpose of locking. 
     In the proximally displaced position of the slide sleeve  46  (FIG. 1 b ) the bracket  48  resiliently springs outwardly and thereby disengages the locking member  50  from the locking element  52 , as indicated by an arrow  51 , whereafter the tool assembly  10 , i.e. the unit comprised of the tool unit  12 , the shaft  18  and the coupling element  20  can be jointly withdrawn from the insert channel  24 . The holding disc  40  ensures that the bearing bush  38  is withdrawn from the insert channel  34  as well. 
     A distal end piece  54  at the distal end of the working shaft  36  serves as distal stop for the slide sleeve  46 . 
     The bearing bush  38  has a slight play in the distal region of the treatment device, which has the effect that imbalances of the tool unit  12  do not have a strong effect, but are compensated by a minimal movement of the bearing bush  38 . This self-balancing increases the lifetime, because the vibrations caused by friction are minimized. 
     A similar effect occurs with the shaft  18 , i.e. the transmission element. The spiral  26  is slightly moved by imbalances in the shaft  18 , i.e. in the braided cable. The movement is made possible by the play between the insertion channel and the plastic mantle  28  about the spiral  26 . Through the slight movement dampened by the plastic mantle, a self-balancing arises which minimizes vibrations. 
     Since, as represented in FIG. 2, a transmission of movement must also be possible via the shaft  18  in curved form the bending modulus of the shaft  18  must be as small as possible to minimize friction. 
     The gyrating mass, which can vibrate, must be held low. The dimensions of asymmetries in the shaft  18  should be as small as possible. The relative surface speed between the shaft  18  and the plastic mantle  28  must be as small as possible. The area of a possible lubrication film about the shaft  18  must be held as small as possible. 
     The diameter of the shaft  18  is therefore important in many aspects with respect to frictional losses. The shaft  18  designed with the smallest possible diameter due to the above factors. Only a small torque need be transmitted, because the pressing forces of the working head  14  of the tool unit  12  are normally small. That is, the diameter of the shaft  18  should only be large enough such that the maximum torque of the motor  22  can be transferred. 
     The provision of self-balancing and vibrational damping of the tool assembly  10  allow high rotary speeds, for example above 30.000 rpm, without problem. In addition, the required motor rating is minimal, e.g. 2 watts, due to the miniaturization of the shaft  18 , the tool unit  12  and the coupling element  20 , which allows the use of a small motor and a sophisticated device design. 
     Instead of a braided cable, the flexible shaft  18  can also be configured as a profile, e.g. a wire, a tube or an angular profile, and in particular can be made from a highly flexible alloy like Nitinol®, or Tinel®. 
     Further embodiments of the invention for example make use of compressed air instead of electricity as the drive power for the motor  22 , or for vibrational damping of the shaft  18 , make use of a liquid bath in which the shaft  18  rotates. 
     Referring to FIG. 1, a channel  62  for guiding an endoscope  56  is present in the working shaft  36  of the treatment device besides the insert channel  34  and parallel thereto. In FIG. 1 a  the distal end of the endoscope shaft is represented only. The endoscope  56  includes a light supply (not shown) from the distal side of which illuminating light  58  emerges. The endoscope  56  further includes endoscope optics, in order to endoscopically observe a working area which also includes the working head  14  of the tool unit  12 . The field of view of the endoscope optics is designated by reference numeral  60 . 
     With reference to FIG. 3 a first embodiment of an endoscopic treatment device  70  having a rigid working shaft  74  is now described. 
     The working device  70  comprises a standard rigid endoscope or borescope  72  having a view direction of 0° to about 30°, which can be inserted in the working shaft  74  and locked via a bayonet lock  84 . The working shaft  74  includes the insert channel  34  for the exchangeable tool assembly  10  according to FIG.  1 . 
     In the exchangeable tool assembly  16  the wearing parts, such as the working head  14  (depending on the specific application), the bearing bush  38  and the flexible shaft  18 , are collected to form an accessory assembly or unit, easily exchangeable by the user. Further universal working channels can be integrated into the working shaft  74 . These can be used for probes (grasping forceps, driven or non-driven tools, sensors, additional light fibers, UV analysis light, UV curing light, laser treatment fibers, fiber optics for observation or spectroscopy, etc.) and/or media (adhesives, coatings, dyes, chemicals, coolants, lubricants, powder, compressed air, gas, water, etc.). The suctioning of material out of the treatment area is also possible (grinding dust, contaminations, sample removal for analysis). 
     The afore-mentioned working channels are preferably provided with a standard coupling connector  78 , for example a Luer connector. Apart from supply lines, probes etc. can also be connected there. A view window  76  of the endoscope  72  lies approximately at the front face of the distal end of the working shaft  74 . A handgrip housing  80  is provided at the proximal end of the working shaft  74 , which contains the drive motor  22 , switches  81 , and electronics in its interior. The handgrip housing  80  further serves as a base for the securement and passage of the working channels mentioned before and a connector cable  82 . The low weight and the form of the handgrip housing  80  allow an ergonomic holding of the handle. The length of the handgrip housing  80  however is as short as possible, which favors a longer working length. 
     The connector cable  82  is connected to a multifunctional supply unit  86  (shown in FIG.  4 ), which apart from supplying power (primarily electricity, but also compressed air is possible) for the motor  22  can also supply illumination light for the endoscope  72 . 
     In operation, illumination light from a light source is passed through the light connector  73  into the endoscope  72 . The light emitted from the distal end illuminates the cavity and the working head  14 . The treatment device  70  operates with high rotary speeds, similar to a dental drill, which enables large removal capacities and exact guidance with small pressing forces. 
     The treatment device  70  can be activated either with the switch  81  on the handgrip housing  80  or with a foot switch (not shown). Preferably, the rotary speed can be adjusted to account for the tool unit  12  or the working head  14  and the working situation. 
     The direction of rotation is possible in both directions with certain flexible shafts  18  so that the direction of rotation can be chosen to account for the working situation. The rotation can also be intermitting and/or alternating if this is advantageous for example for a better precision and/or removal capacity. 
     The treatment device  70  can be guided under visual control through the endoscope  72  to the treatment location where the treatment can begin immediately. 
     The expensive endoscope  72  can be easily removed from the working shaft  74  at any time due to the modular construction. This is made possible by the easily releasable connection by means of the universal bayonet connection  84 . The separated endoscope  72  enables a more precise inspection of the location to be treated, because the optics can be placed more closely to the surface for enlarged detail images, because the device is not held at a distance caused by the working head  14  of the tool assembly  10 . 
     FIG. 4 shows a further embodiment of a treatment device  90  similar to the treatment device  70  in FIG. 3 so that only the differences are described in the following. 
     A working shaft  92  of the treatment device  90  is, compared with the working shaft  74  of the treatment device  70 , provided with a flexible part or a linkage  94  so that the tool unit  12  with the working head  14  of the tool assembly  10  can be deflected. For reasons of mechanical stability, the deflection is preferably in one direction up to a predefined stop. When reaching the stop, the linkage is designed to abruptly become stiff. This stiffening improves the precise guidance of the tool unit  12 . The deflection in only one direction still allows treatment in a large region in a cavity, because the treatment device  90  can also simply be rotated about its longitudinal axis. An endoscope  96  of the treatment device  90  according to this embodiment comprises, differently from the embodiment according to FIG. 3, a view direction of about 70°, wherein a view window  98  is provided before the linkage  94  by means of a corresponding opening in the mantle of the working shaft  92 . The deflection of the distal end of the working shaft  92  in this embodiment is about 90°. The dimensions, the view direction and the view field (e.g. 30°) are coordinated such that the working head  14  lies at a suitable position in the image of the endoscope  96 , e.g. in the center of the image or in the lower one-third, so that a suitable detail imaging of the surface to be treated is made possible. The angle of deflection and the view field, etc. are dependent upon the application. 
     The deflection of the distal end of the working shaft  92  is preferably achieved with a relatively small ripped rotary knob  100  at the proximal end of a handgrip housing  102  via a preferably bidirectional Bowden connection (not shown). A self-retarding threading is located in the interior of the rotary knob  100 , which converts the rotation of the rotary knob  100  into a translation of the Bowden cable. An overextension of the Bowden cable in both directions is prevented by stops in the mechanism of the rotary knob  100 . 
     The movable element of the bidirectional Bowden connection is configured as a braided cable and a spiral tightly surrounding the cable, which is fixedly secured at least at both ends. The traction is transmitted through the cable, the thrust through the spiral. A rigid tube forms the outer sheath of the Bowden connection for guiding and receiving the counter forces. 
     Cross-sectional area is saved by the bidirectionality of the Bowden connection, because only one cable is required for straightening and bending the distal end, which is loaded under traction and thrust. The normal counter-cable used in deflectable endoscopes is not needed. Without the counter-cable, one has more freedom in the selection and distribution of other elements in the interior of the working shaft  92 . Further, the pivot point of the deflecting members can be displaced asymmetrically from the center at a position lying opposed to the cable. This produces a larger lever action for the deflection and therefore a larger deflection force. At least one working channel or insert channel can be provided, as has been described with reference to FIG. 3 or to FIG.  1 . 
     The treatment device  90  is introduced approximately up to the working position in the straight configuration. Introduction under visual control is possible with an inserted fiber optic probe, because the endoscope  96  is not provided with a straight ahead view. After reaching the approximate working position, the distal end is placed in its working position with the rotary knob  100 , where the advantageous stiffening takes place at the end of the stop. A variation of the linkage  94  also provides a mechanism by which a stiffening of the flexible part  94  is possible in arbitrary deflection position through a further actuator element, without having to deflect entirely up to the stop. 
     When the proper deflection position is adjusted, the motor  22  can be activated and the endoscopic treatment on the surface can be carried out under simultaneous observation. 
     The treatment device  90  is preferably removed from the treatment area again in the straightened configuration. Analogously to the embodiment of FIG. 3, the endoscope  96  can be removed from the working shaft here for enlarged detail imaging of the surface by using the disassembled endoscope  96 . 
     A modification of the embodiment shown in FIG. 4 consists of not using a rigid endoscope  96 , but instead a fiber optics assembly which has a viewpoint from the end face of the deflectable distal end. The deflection mechanism and the additional working channel are configured analogously to the embodiment of FIG.  4 . 
     A large variety of surface geometries can be treated with the three embodiments.