Patent Publication Number: US-2023144859-A1

Title: Endoscope

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of U.S. patent application Ser. No. 17/204,119, filed Mar. 13, 2021 and issued as U.S. Pat. No. 11,553,113 on Jan. 10, 2023, which is a continuation of U.S. patent application Ser. No. 16/860,831, issued as U.S. Pat. No. 10,965,844 on Mar. 30, 2021, which is a continuation of U.S. patent application Ser. No. 15/576,816, issued as U.S. Pat. No. 10,645,260 on May 5, 2020, which is a § 371 application of International Application Number PCT/DK2016/050150, filed May 26, 2016, which claims priority from Denmark Patent Application Number PA 2015 70319, filed May 27, 2015, all said applications incorporated herein by reference in their entirety. 
     The following applications disclose related subject matter: U.S. patent application Ser. No. 15/576,812, issued as U.S. Pat. No. 10,646,107 on May 12, 2020; U.S. patent application Ser. No. 15/576,813, issued as U.S. Pat. No. 10,631,716 on Apr. 28, 2020; U.S. patent application Ser. No. 15/576,814, issued as U.S. Pat. No. 10,624,531 on Apr. 21, 2020; U.S. patent application Ser. No. 15/576,815, issued as U.S. Pat. No. 10,617,284 on Apr. 14, 2020; U.S. patent application Ser. No. 15/576,817, issued as U.S. Pat. No. 10,624,617 on Apr. 21, 2020; U.S. patent application Ser. No. 15/576,818, issued as U.S. Pat. No. 10,779,710 on Sep. 22, 2020; and U.S. patent application Ser. No. 16/839,991, issued as U.S. Pat. No. 11,337,588 on May 24, 2022; U.S. patent application Ser. No. 16/920,358, issued as U.S. Pat. No. 11,478,135 on Oct. 25, 2022; and U.S. patent application Ser. No. 17/931,571, filed on Sep. 13, 2022. 
    
    
     TECHNICAL FIELD 
     The present invention relates to an endoscope, in particular but not exclusively a disposable camera endoscope, having an operating handle arranged at a proximal end thereof and an insertion tube extending from said handle towards a distal end of the endoscope. 
     BACKGROUND 
     In general, an endoscope comprises an operating handle at the proximal end and an insertion tube extending from the handle towards the distal end. The handle is adapted to be held by an operator and inter alia comprises externally protruding operating members connected to internal control means allowing the operator to control the motion of the distal end of the insertion tube, while advancing the distal end of the insertion tube to a desired location e.g. within a body cavity of a person. Examples of such endoscopes are disclosed in WO2013/071938A1 and WO2010/066789A1. 
     In modern endoscopes the tip forming the distal end of the insertion tube comprises a camera and illumination means allowing the operator to see his actions on a monitor connected to the endoscope. This necessitates supply and signal cables to be drawn between the tip and the monitor. In the tip space is very limited and generally there is no or little room for electronics, such as an amplifier. The signals from the imaging chip of the camera may thus not be amplified at the source. Transmitting directly weak signals all the way to the monitor, is undesirable because weak signals are more prone to disturbances from noise picked up by long cables, than stronger signals would be. Moreover, weak signals may be prone to attenuation in connectors in the signal path, e.g. the plug and socket connection to the monitor, and would thus require expensive high quality connectors. 
     It is thus desirable to interpose amplification and signal processing means in the signal path from the tip of the insertion tube to the monitor, preferably at a location where more space is available, such as in the handle of the endoscope. 
     In the handle, however, there may in some clinical situations be a risk of undesired contact with fluids. Main problem is water, which may disturb or ruin the electronics, in particular aqueous saline solutions, but other electrolytes may also pose problems. 
     It is therefore necessary to protect the electronics in a protected manner, sealed from such fluids. 
     SUMMARY 
     According to the present invention this object is achieved by an endoscope having an operating handle comprising a handle housing arranged at a proximal end thereof, an insertion tube extending from said handle towards a distal end of the endoscope, and a sealed compartment adapted to accommodate electronic circuitry of the endoscope and arranged at least partially within said handle housing, characterized in that said compartment furthermore comprises a cable conduit extending from said mounting plate towards the distal end of the endoscope, said conduit being terminated in a sealing manner at the distal end of the endoscope. 
     This has multiple advantages. Main advantage is that having a dedicated sealed compartment obviates the need of sealing the outer handle housing, which itself is difficult because the housing must allow for movable parts such as the operating buttons to protrude through the handle housing. In particular, it provides a single sealed compartment in which the electrical cables to the camera in the tip of the endoscope are also protected from undesired fluids. Despite this fact, the outer housing does provide some shielding and to some extent a two layer barrier against influx of undesired fluids is thus provided. Furthermore, because the inner compartment is not subject to the same ergonomical constraints as the outer housing, it is much easier do design a joint which is easy to seal, e.g. follows straight lines, than a joint between ergonomically shaped outer housing parts. Finally, because the inner compartment is much smaller than the outer housing the joints will be much shorter and thus easier to seal, i.e. less prone to bad gluing or welding as the case may be. 
     According to a preferred embodiment the sealed compartment comprises a mounting plate adapted to carry said electronic circuitry, and a cover connected to the mounting plate, so as to enclose the electronic circuitry. The mounting plate and the cover may thereby be devised to join each other in a plane and may thus be designed with easily joined straight lines. 
     According to a further preferred embodiment, the operating handle comprises a shell structure. Using a shell structure with several shell parts facilitates the assembly of the endoscope, and in particular access to inner components in the handle when mounting them. 
     According to a further preferred embodiment, the operating handle comprises an inner, essentially shell shaped chassis having a shell structure with a shell wall with an inner surface and an outer surface linked by an edge, said shell structure defining an interior compartment delimited by said inner surface and the edge of the shell wall, the edge thus defining main opening of said interior compartment, and in that the mounting plate is adapted to engage said shell shaped chassis in the vicinity of the edge, so as to partially cover said inner compartment. In this way the mounting plate may be used to stabilize and increase the rigidity of the shell shaped chassis, in turn allowing the shell shaped chassis to be weakened by apertures provided in the wall and or by the use of a further reduced wall thickness, be it localised or overall. 
     According, to another preferred embodiment the mounting plate comprises a number of flanges adapted to extend into the interior compartment when the mounting plate is in engagement with said chassis and partially covers the inner compartment. Providing such flanges allow the separation between inner parts. In particular movable ones, such as control cables, may be kept separate from other parts which may be prone to damage from the moving cables. 
     According to a further preferred embodiment, the cable conduit is accommodated within an outer sheath of the insertion tube. Thereby additional protecting against undesired fluids is provided. 
     According to yet another preferred embodiment, at least one of said mounting plate or said cover is made from a transparent plastic material. If one, or preferably both of said mounting plate and said cover is made from transparent material, the two parts may efficiently be sealed along the joint by the use of UV curing glue or resin. Likewise applies to the joining of the mounting plate to the chassis if desired. 
     A person skilled in the art will appreciate that any one or more of the above aspects of this disclosure and embodiments thereof may be combined with any one or more of the other aspects of this disclosure and embodiments thereof. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The present invention will now be described in greater detail based on non-limiting exemplary embodiments and with reference to the drawings, on which: 
         FIG.  1    shows an exploded overview of an endoscope according to the present invention and how this exploded view is split in a left-hand side part and a right-hand side part for better visibility in  FIG.  1   a    and  FIG.  1     b,    
         FIG.  2    shows a perspective view of the fully assembled endoscope of  FIG.  1   , 
         FIG.  3    shows a monitoring device adapted for mutual connection with the endoscope of  FIG.  1   , 
         FIG.  4    shows a first perspective view of a chassis of the endoscope of  FIG.  1   , 
         FIG.  5    shows a second perspective view of the chassis of  FIG.  4   , 
         FIG.  6    shows a third perspective view of the chassis of  FIG.  4   , 
         FIG.  7    shows a perspective view of the chassis of  FIG.  4    with control cables and a control member mounted, 
         FIG.  8    shows a semi-assembled endoscope according to the invention with the chassis, movable parts and a housing shell part, 
         FIG.  9    shows a top perspective view of a mounting plate for carrying electronics of the endoscope, 
         FIG.  10    shows the mounting plate carrying the electronics of the endoscope with electrical wiring extending therefrom, 
         FIG.  11    shows bottom perspective view of a cover adapted to fit the mounting plate of  FIG.  9   , 
         FIG.  12    shows a top perspective view of an assembly of the mounting plate of  FIG.  9    and the cover of  FIG.  11   , and 
         FIG.  13    shows a bottom perspective view of the assembly of  FIG.  12   . 
     
    
    
     DETAILED DESCRIPTION 
     Turning first to  FIG.  2    an assembled endoscope  1  according to the present invention is shown. The endoscope  1  has a proximal end with an operating handle  2  to be held in one hand by an operator. Accordingly, the operating handle is shaped in a manner ergonomically suitable for operator, in particular but not exclusively for the hand of the operator, as arms and joints may also play a role in the ergonomics. From the handle  2  an insertion tube  3  extends towards the distal end of the endoscope. At the distal end of the endoscope  1  the insertion tube  3  ends in a bending section  4  and a tip part  5 . The bending section  4  is in mechanical connection with an operating member  6 , digitally operable by the operator, e.g. by the thumb, thereby allowing the operator to bend the tip part  5  in a desired direction when advancing the insertion tube  3  towards a desired location, e.g. through a body cavity of a patient. As can also be seen the endoscope  1  comprises a flexible connection cable  7  with a connector  8  allowing the endoscope  1  to be connected to a monitoring device such as a monitor  92  shown in  FIG.  3    forming part of an endoscope  1  and monitor  92  system. 
     Turning now to  FIGS.  1 ,  1     a  and  1   b , an exploded view of the endoscope  1  is shown. As mentioned, the endoscope  1  has an operating handle  2  at the proximal end thereof i.e. at the left-hand side of  FIG.  1   a   . The operating handle  2  is assembled from and comprises a number of handle parts to be described later. From the operating handle  1 , the insertion tube  3  comprising a number of insertion tube parts to be described later extends towards the distal end of the endoscope, i.e. towards the right-hand side of  FIG.  1     b.    
     As can be seen in  FIG.  1   a   , the operating handle  2  comprises at least two shell parts  9 ,  10  forming the outer housing walls of the handle housing of the operating handle  2 . The two shell parts  9 ,  10  form the outer housing walls and are shaped to provide an ergonomically suitable operating handle for an operator, gripping it with one hand. In addition to the two shell parts  9 ,  10  a transition part  11  forming the transition from the operating handle to the insertion tube  3 , may be provided. This transition part may also form part of the handle housing. However, the two shell parts  9 ,  10  constitute the major part of the housing in the embodiment shown. 
     The two shell parts  9 ,  10  are adapted to engage and be held and be supported by a chassis  12 , in turn, adapted to support said at least two shells parts  9 ,  10  by suitable engagement means, such as recesses and/or protrusions  13  interlocking with suitable complementary means  14 ,  15  on the chassis  12 , better visible in  FIGS.  4  and  5   . Furthermore the shell part  10  has pair of columns  88  of which only one is visible in  FIG.  1   a   . These columns  88  serve the attachment of the shell part  10  to the chassis  12 . The shell part has internal engagement means (not visible) adapted to engage the shell part  9  at the proximal end of the endoscope  1 , so as hold them together. At the other end the shell parts are held together by the transition part  11 . 
     Turning now to the  FIGS.  4 ,  5  and  6   , the chassis  12  will be described in greater detail. The chassis  12  preferably shell shaped, i.e. said chassis comprises an essentially shell shaped structure with a shell wall having an inner surface  16  and an outer surface  17  linked by an edge  18 , said essentially shell shaped structure defining an interior compartment  19  delimited by said inner surface  16  and the edge  18  of the shell wall, the edge thus defining main opening  20  of said interior compartment  19 . It will be understood that the chassis  12  can be designed mainly based on technical requirements, such as kinematic chains of movable parts, and thus be optimized for those technical requirements without having to inherit constraints from the ergonomic requirements of the handle  2 , i.e. the shape of the two shell parts  9 ,  10 . 
     Best visible in  FIGS.  4  and  5    are a number of different apertures and cut-outs formed in the chassis  12 . These apertures form vias for different purposes between the interior compartment  19  and the exterior of the chassis  12 . 
     The different cut-outs and apertures differ in shape, size, location and layout depending on their purposes, and may as mentioned be designed according to technical requirements, independently of the ergonomic requirements of the handle  2 . 
     Starting from the proximal end of the endoscope  1  there is an aperture  21 , as best seen in  FIG.  6   . The aperture  21  accommodates a push button  22 , so that the push-button  22  extends from the interior compartment of the chassis  12  to the exterior, and on through an aperture in the shell part  9  to be accessible by an operator holding the handle  2  of the endoscope  1 . The push-button  22  is preferably biased towards an external position by means of two coil springs  83  guided by two guiding columns  84  fixed in the bottom two wells provided in the chassis  12 , preferably by gluing using UV-curable glue or resin transmitted through the transparent material of the chassis  12 . The two guiding columns  83  further serve to reduce friction between the coil springs  83  and the columns  88 . They are therefore preferably made of a material with relatively low friction, such as low-density polyethylene LDPE, e.g. Comothene® 4812. 
     On the outer surface  17  of the shell wall of the chassis  12  two lugs with holes  89  are provided. These serve to engage the columns  88  on the shell part  10  for attaching it to the chassis, as described above. 
     In the shell wall two elongate apertures  23  in the form of slits are provided. The two elongate apertures  23  are preferably arranged as a pair, one on either side of the aperture  23 . The two elongate apertures  23  serve as guide means for the push-button by accommodating a respective protrusion  24  provided on the surface of the push-button  22 . 
     In the vicinity of the two elongate apertures  23 , a first and a second pair of apertures  25 ,  26  in the form of essentially cylindrical through holes are provided. The first pair of essentially cylindrical apertures serve as pivotal bearings for trunnions  27  of a control lever  28  for maneuvering the bending section  5  via a pair of Bowden pulls  29 . As can best be seen in  FIGS.  1  and  2   , the control lever  28  is attached to the control knob  6 , and at least the control knob extends to the outside of the endoscope handle  2  through a slit  30  in the shell part  10  to be accessible by a thumb of the an operator. It should be noted that it is not essential for the function as bearings for the trunnions  27  of the control knob, that the holes are though holes, but because the chassis is preferably injection moulded, through holes may be much easier manufactured than e.g. blind holes. 
     It will be understood that due to the slit  30  and other necessary openings in the shell parts  9 ,  10 , the handle housing does not protect the internal components fully. Though some protection against spray and splash is provided by the shell parts  9 ,  10  there is basically fluid communication between the exterior and the interior of the handle housing. This is largely intended, as sealing these openings would be unnecessarily complicated and costly. 
     The second pair of apertures  26  are preferably also circular through holes and have the same diameter. They need not be circular, however, as their purpose is allowing the insertion of a tool, such as a rod in order to immobilise the control lever  28  during assembly of the endoscope, more specifically when attaching the proximal ends of the cables  31  of the two Bowden pulls  29  to the control lever  28 . Accordingly, the control lever  28  has a through hole  32 , corresponding in size to the apertures  26 , and adapted to align with these in one position of the control lever  28 , thereby allowing the insertion of the tool through all three holes,  26 ,  32 , so as to block movement of the control lever  28  with respect to the chassis  12 . The position of the three holes  26 ,  32  are selected so as to block the control lever  28  in a position later corresponding to a neutral position of the control lever  28  and knob  6 , in which the bending section  4  is straight. 
     With the control lever  28  blocked during assembly the cables  31  Bowden pull may be attached to the control lever  28  in a well defined manner. This is preferably done by threading the respective free end of each cable  31  through suitable passages in the control lever  28 , forming a loop  43  by looping the free ends back to the respective cable and crimping the free end onto the cable  31  using a barrel  33 . The barrel  33  may be of the open barrel type, to avoid the hazel of sliding the barrel  33  on onto the cable  31  prior to crimping. Evidently, other attachments for the loop  43 , such as protrusions, may also be used. Furthermore, entirely different attachments methods without loops are also envisaged, albeit not preferred. 
     To facilitate this assembly process a cross-shaped aperture  34  is located in the vicinity of the bottom of the chassis  12 , i.e. away from the main opening  20  defined by the edge  18 . Likewise a cut-out  35  in the wall from the edge  18  is provided. The cross-shaped aperture  34  and the cut-out  35  allows access to the cables  31  various tools, such as holding and crimping tools during the assembly. 
     As can best be seen in  FIG.  5    the cross-shaped aperture  34  a further, essentially rectangular aperture is generally aligned with a further rectangular access aperture  36  and a pentagonal aperture  37  in the direction towards the proximal end of the endoscope  1 . The cross-shaped aperture  34 , the rectangular aperture  36  and the pentagonal aperture  37  are separated by respective bridges  38  and  39 . These bridges  38 ,  39  do not follow the general curvature of the outer surface  17  of the chassis  12  but are indented to form a generally V-shaped groove  40  connecting the cross-shaped aperture  34  to the pentagonal aperture  37  via the rectangular aperture  36 . As can be seen from  FIG.  7   , this V-shaped groove  40  in the outer surface  17  provides the outer surface  17  with a means for guiding one or more movable parts, in particular the cable  31  of the Bowden pull between two apertures, such as the cross-shaped aperture  34  and the pentagonal aperture  37  along the outer surface  17  outside of the interior compartment  19 . This in turn allows the unsupported free end of the cable  31  of the Bowden pull to follow a straight line. At the same time, because the unsupported free end of the cable  31  passes from the interior compartment  19  of the chassis  12  to the exterior via the cross-shaped aperture  34 , the cable  31  becomes easily accessible for the assembly tools, in particular the crimping tool. The cross-shape of the cross-shaped aperture, in turn, facilitates the use of the tools by providing the necessary space for opening and closing the tools, be it a crimping tool or a holding tool. 
     In  FIGS.  4  and  5    a further pair apertures  41  in the form of essentially cylindrical through holes can be seen. Similar to the apertures  25 , the further pair of apertures  41  serve as bearings of trunnions  42  carrying a pinion  44 . The pinion  44  is adapted to be in engagement with a curved rack  45  having a first free end  46  and a second end with trunnions  47  held loosely in suitable receptacles inside the push button  22 . The rack  45  as such is loosely held in a guideway comprising a first side  85 , a second side  86  and a curved bottom  87  adapted to keep the rack  45  in engagement with the pinion  44 , cf.  FIG.  6   . The first side  85  and the second side  86  as well as the curved bottom  87  are preferably formed integrally with the remainder of the chassis  12 , e.g. in an injection moulding process. The first side is preferably constituted by a plane surface of a thickened part of the wall, i.e. a raised part of the inner surface  16  of the chassis  12 . 
     Rotation of the pinion  44  may be effected by an operator moving the push-button  22 , e.g. depressing it using an index finger, upon which the push-button transfers motion to the curved rack, in turn rotating the pinion  44 . 
     On the pinion  44 , two lever arms  48  and  49  of different lengths are provided. These arms  48  and  49  are in rigid connection with the pinion  44 . Via a number of intermediate parts  50 ,  51 ,  52 ,  53  and  54  a desired operation of a tool  55  at the tip part  4  at the distal end of the endoscope  1  may be effected when the pinion  44  is rotated. The manner in which the operation of the tool  55  is to be effected may depend on the details of the tool. Variations in requirements can be controlled in dependence on the differences in lengths of the lever arms  48  and  49 , and possibly articulations of the intermediate part  50 , at the design stage of the endoscope  1  with a tool for a specific purpose. 
     As can best be seen in  FIGS.  4  and  6    a number of apertures  56  are arranged to form openings from shelves  57  on the inner surface  16  of the chassis  12  to the outer surface  17  of the chassis  12 . These openings are adapted to form undercut receptacles for protruding barbs  58  on a mounting plate  59  best seen in  FIGS.  9 ,  10  and  13   . The mounting plate  59  is preferably injection moulded from the same transparent plastic material as the chassis  12 . Using a transparent plastic material is advantageous in that it allows parts to be joined and/or sealed using an UV curable glue or resin, i.e. one that hardens under the influence of ultraviolet light. In respect of glue or resin, be it UV curable or not, it has been found that simply gluing the proximal end portions of the outer tubes  60  of the Bowden pulls  29  in suitable recesses  61  provided along the inner surface  16  of the shell wall is sufficient to secure the Bowden pulls  29  in position. This is primarily, because, as it has been realized, adjustment is not needed. Adjustment, in turn, is not necessary because any slacking of the pull cable  31  of the Bowden pull  29  is negligible in a disposable endoscope  1 . The pull cables  31  are not under any substantial tension during shelf life and will hardly undergo any mentionable stretching during the one short occasion the disposable endoscope  1  is in use. 
     The mounting plate  59  when attached to the chassis  12 , and possibly secured thereto by preferably UC curing resin or glue, forms a partial lid over the main opening  20 , and hence partially encloses the interior compartment  19 . Closing the interior compartment partially on all four sides, rather than only three, adds rigidity to the chassis  12  as it hinders lateral compression, i.e. of the shell walls towards each other. Accordingly, the chassis  12  and in particular the walls parts thereof may be made with a reduced strength, i.e. thinner or with more or larger apertures than would otherwise be possible. 
     As the name suggest, the reinforcing of the chassis  12  it not the main purpose of the mounting plate  59 . Rather, the mounting plate  59  is adapted to carry electronic circuitry of the endoscope  1 , e.g. on a printed circuit board  62 , as can best be seen in  FIG.  10   . In the following the electronic circuitry on the printed circuit board  62  will be referred to as main electronics. This is mainly to distinguish from other electronics located at or embedded in the tip  4  of the insertion tube  3  of the endoscope  1  which will accordingly be termed tip electronics. Both for the term main electronics and the term tip electronics it should be borne in mind that this description relates to a non-limiting exemplary embodiment, and that no functionality requirements should be attributed to these terms. 
     In modern camera endoscopes  1  the tip part  4  forming the distal end of the insertion tube  3  comprises a camera, such as a CCD camera, and illumination means, such as an LED, allowing the operator to see his actions on a monitor  92  connected to the endoscope  1 . This necessitates supply and signal cables or wires  7 ,  63  to be drawn between the tip part  4  and the monitor  92 . In the tip part  4  space is very limited and apart from the camera and illumination means there no or little room for electronics, such as an amplifier. The signals from the imaging chip of the camera may thus not be amplified at the source. Therefore the weak electrical analogue signals from the camera which are prone to disturbance by electrical noise picked up by signal wires, cables etc. on the way to the monitor  92 . To overcome this, the main electronics acts as an intermediate between the tip electronics electrical power supply and amplification. Thus the weak signals from the camera arriving on the wires  63  may be amplified and otherwise modified, e.g. digitally encoded before they are transmitted to the monitor  92  via the flexible external connection cable  7 . The present invention thus takes advantage of the fact that in the handle  2  of the endoscope  1  there is much better room for the amplification and signal processing means than anywhere else in the signal path from the tip part  4  at the distal end of the insertion tube  3  to the monitor  92 . 
     Furthermore, with the main electronics being located on the mounting plate  59  in conjunction with the chassis  12  it becomes possible to accommodate the electronics according to technical requirements, without much consideration to ergonomic properties and the general layout of the handle  2 . One particular technical requirement is the protection of the electronics against undesired contact with fluids such as water, which may disturb or ruin the electronics, in particular aqueous saline solutions. Other electrolytes may also pose problems, but main problem is water which in many clinical situations is ubiquitous. The traditional approach in multiple-use endoscopes as well as in single use, i.e. disposable endoscopes  1  has been to seal the outer housing. This, however, is difficult and costly because the integrity of the housing needs to be breached in order to allow the passage of movable operating parts, such as in the endoscope  1  according to the present invention the push-button  22  and the control button  6 . 
     Accordingly, the present invention realizes that by fitting a suitable cover  64  a sealed compartment for the main electronics may be provided within the handle, thus obviating the need for sealing the outer housing of the handle  2 . The skilled person will understand that this applies, not only to the operating handle with a chassis  12  on which the preferred embodiments are based, but to operating handles for endoscopes in general. Thus the mounting plate  59  could also be mounted and directly within a shell part of an operating handle without a chassis  12 , thereby protecting the main electronics, and possibly reinforcing the shell part mechanically. 
     The cover  64  has an edge  65  which essentially lies in a single plane except for a passage  66  for the cables  7 ,  63  to enter and exit the compartment. The edge  65  is thus adapted to engage a plane surface of the mounting plate  59  in close vicinity of the edge  68  of the mounting plate  59 . As can be seen the edge  68  is preferably raised along the circumference of the mounting plate thus facilitating the positioning, attaching and sealing of the cover  64  with respect to the mounting plate  59 . This attaching and sealing of the cover  64  with respect to the mounting plate  59  is preferably also performed using UV curable glue or resin, and accordingly the cover  64  is therefore also made of transparent plastic material, e.g. injection moulded like the chassis  12  and mounting plate  59 . The chassis  12 , mounting plate  59  and the cover  64  are preferably all made of the same material, thus facilitating the choice of a glue or resin with suitable adhesive and cohesive properties. This glue or resin may also be used to seal directly around the cable  7  and wires  63  at the passage  66 . Preferably, the mounting plate  59  has a receptacle  69  in the shape of a half-pipe, serving to receive and hold the cable  7  and wires  63  as well as serve to limit the amount of UV curable glue or resin used when sealing the compartment around the cable  7  and wires  63 . 
     In a preferred embodiment, however, the glue or resin does not seal directly around the cable  7  and wires  63 . Instead the wires  63  are drawn from the compartment to the tip part  4  of the insertion tube  3  of the endoscope  1  within a wire or cable conduit  70 , seen only in  FIG.  1   . Consequently, the sealing at the passage  66  will be around the conduit  70  and the cable  7 . The conduit  70 , in turn, is sealed at the tip part  4  at the distal end of the insertion tube  3  of the endoscope  1 , thereby providing a sealed compartment extending all the way to the tip part  4 , where it is preferably moulded in together with the camera housing. This sealed compartment protects the wires  63 , which are relatively thin, against mechanical stress while preserving the sealing properties. 
     On the opposite side of the mounting plate  59  away from the compartment and the printed circuit board  62 , two perpendicular flanges  77  are provided. These confer additional rigidity to the mounting plate  59  but their main purpose is to serve as protective barriers for a flexible hose  71  of a working channel of the endoscope  1 . Like many prior art endoscopes, the endoscope  1  of the present invention comprises a working channel e.g. allowing liquid or fluid to be delivered to or extracted from the body cavity into which the endoscope has been advanced. 
     Starting from the distal end of the insertion tube  3  of the working channel as a first tube segment  72  attached to and preferably embedded in the tip part  4  at one end. The second end of the first tube segment  72  is connected to a first end of a second tube segment  73  by means of a short length of rigid tubing  74 . Rigid in this sense is to mean more rigid than the second tube segment  73  which, in turn, is more rigid than the first tube segment  72  which has to comply with the flexibility requirements of the bending section  5 . Similarly, the first tube segment  72  is more rigid than the flexible hose  71 . In this respect it is preferred to make the flexible hose  71  of a first polyurethane elastomer and to make the first tube  72  of another polyurethane elastomer. Both polyurethane elastomers could be Pellethane®, which is available in different variants. The second tube segment  73  may also comprise polyurethane. The second end of the second tube segment  73  is connected to a T-joint  75  in connection with a connector  76  or lead-in mounted on chassis  12  in connection with a circular aperture  91  and serving to connect a hose of a suction or irrigation means to the working channel so as to extract or deliver aforesaid liquid or fluid to the body cavity into which the endoscope has been advanced. 
     However, in the endoscope  1  according to the present invention the working channel serves not only fluids or liquids, but also serves as a working channel for the tool  55 , which means that a sealing is necessary where the motion of the lever arms  48  and  49  are transferred to the movable intermediate parts  53  and  54  which are largely accommodated within the first tube  72  and the second tube  73  of the working channel. This sealing is achieved by the use of the flexible hose  71  which is fixed at one end at the intermediate part  51  and at the other end at the T-shaped joint  75 . The hose  71  may have a smooth surface in a relaxed state or it could be corrugated to form a bellows. The hose  71  is of a highly flexible thin-walled material as compared to the first tube  72  and the second tube  73  of the working channel, because it has to be able to comply with the relative motions between the intermediate parts  50 ,  51 ,  52  which is a compound translatory and rotational movement in two dimensions with respect to the chassis  12 . 
     This compound translatory and rotational movement in two dimensions with respect to the chassis  12  make the hose  71  prone to damage from other movable parts of the endoscope  1 . This is in particular the case for the cables  31  of the Bowden pulls  29  and certainly the crimps  33  even though some protection is achieved by guiding the cables  31  outside of the chassis  12  in the V-shaped grooves  40 . As mentioned above, this protection is further increased by at least one of the flanges  77 . 
     This compound translatory and rotational movement in two dimensions with respect to the chassis  12  is quite substantial, and to accommodate for the movement of the intermediate part  50  in one direction the rectangular aperture  36  is provided in the wall of the chassis  12 . In the other direction the bottom  78  of the mounting plate between the flanges  77  serves as a strike plate to limit motion of the intermediate part  50  so as to be abutted by the claw like end  79  thereof which clamps and holds the intermediate member  52  inside the hose  71 . This limitation of the motion prevents the section of the hose  71  located between the claw like end  79  and the intermediate part  51  to which the hose  71  is attached to be overstretched and rupture. The flanges  77  serve also to guide and control the movements of the hose  71  and claw like end  79 , in particular in the lateral direction. 
     The entire insertion tube  3  is sealingly encapsulated in a flexible outer tube. The outer tube comprises a first outer tube section  80  and a second outer tube section  81  joined with a sleeve  82 . Similarly to the working channel the first outer tube section  80  is more flexible than the second tube section  81  in order to comply with the movements of the bending section  5 . The second tubular member  73  is however still quite flexible. More specifically, the second tubular member  73  and a second outer tube section  81  surrounding it are so flexible that they allow a loose knot to be tied on the insertion tube  3 . The alternative is a rigid or semi-rigid endoscope where the insertion portion is rigid, only slightly bendable or hinged, and which does not allow a knot to be tied on the insertion tube. Preferably, the first outer tube section  80  is made from the very same material as the hose  71 , either of them simply cut to a suitable length from a stock of tubular material for the respective purpose. 
     Returning now to  FIG.  1    a, a protective tubular member  90  can be seen. The intermediate part  11  has a slightly frustoconical section adapted to receive one end of the protective tubular member  90 . The protective tubular member does not form part of the endoscope  1  as such but serves as a protective means during storage.