Abstract:
A process for producing the actuating part of an instrument for endoscopic applications, which instrument comprises a tubular member having a handling end portion with a flexible portion and an actuating device located at another end portion, which actuating device comprises a cylindrical part connected to the handling end portion, a cylindrical part connected to the actuating device and a number of longitudinal elements for transferring the movement of the actuating device to the handling end portion, the actuating device being made beginning with a full cylindrical tube which is provided with a number of longitudinal slits thereby forming the longitudinal elements.

Description:
BACKGROUND OF THE INVENTION 
     I. Technical Field 
     The invention relates to a process for producing the actuating part of an instrument for endoscopic applications or the like, which instrument comprises a tubular member having a handling end portion with a flexible portion and an actuating means located at another end portion, which actuating means comprises a cylindrical part connected to the handling end portion, a cylindrical part connected to the actuating means and a number of longitudinal elements for transferring the movement of the actuating means to the handling end portion. 
     II. Description of the Related Art 
     An instrument of the above described type has been described in EP-A-1 708 609 and is normally used for applications such as minimally invasive surgery, but it is also applicable for other purposes such as the inspection or repair of mechanical or electronic installations at locations which are difficult to reach. In the detailed description, the term endoscopic applications or endoscopic instrument will be used but the term must be interpreted as also covering other applications or instruments as explained above. 
     In this known instrument, the actuating part needed to steer one end of the instrument by movement of the other end is made out of a number of cables which are connected both to the first and second end portions. Connecting the cables to these portions is cumbersome and complicated in that each cable has to be connected separately and the tension in the cables must be the same for all of the cables so to obtain a reliable control of the movement. This makes the production of such an instrument complicated. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the invention to provide a process for producing the actuating part of an instrument of the above identified type in which this problem is avoided. 
     This object is achieved in that the actuating means is made beginning with a full cylindrical tube which is provided with a number of longitudinal slits thereby forming the longitudinal elements. 
     By having the longitudinal elements made as an integral part of the remaining parts of the actuating operating member, the separate connection of the different parts of this member is avoided and assembling becomes extremely easy. 
     The invention also relates to an endoscopic instrument using an actuating means obtained by the process according to the invention, in which different constructions are used in order to obtain a reliable operation of the actuating means. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other advantages and characteristics of the invention will be clear from the following description, reference being made to the attached drawings. 
       In the drawings: 
         FIG. 1  is a schematic cross-section of an instrument according to the invention. 
         FIG. 2  is an exploded view of the three cylindrical members forming the instrument according to the invention. 
         FIG. 3  is an unrolled view of a part of the intermediate cylindrical member of the instrument according to the invention. 
         FIG. 4  is an unrolled view of a part of a second embodiment of the intermediate member according to the invention. 
         FIG. 5  is an unrolled view of a part of a third embodiment of the intermediate member according to the invention. 
         FIG. 6  is an unrolled view of a part of a fourth embodiment of the intermediate member according to the invention. 
         FIG. 7  is an unrolled view of a part of a fifth embodiment of the intermediate member according to the invention. 
         FIG. 8  is an unrolled view of a part of a sixth embodiment of the intermediate member according to the invention. 
         FIG. 9  is an unrolled view of a part of a seventh embodiment of the intermediate member according to the invention. 
         FIG. 10  is an unrolled view of a part of an eighth embodiment of the intermediate member according to the invention in a pre-assembled condition. 
         FIG. 11  is a cross-section view of the unit with an intermediate member according to  FIG. 11  in the pre-assembled condition. 
         FIG. 12  is an unrolled view of a part of the eighth embodiment of the intermediate member according to the invention in the assembled condition. 
         FIG. 13  is a cross-section view of the instrument with an intermediate member according to  FIG. 10  in the assembled condition. 
         FIG. 14  is an unrolled view of a part of a ninth embodiment of the intermediate member according to the invention in a pre-assembled condition. 
         FIG. 15  is an unrolled view of a part of a tenth embodiment of the intermediate member according to the invention. 
         FIG. 16  is an unrolled view of a part of an eleventh embodiment of the intermediate member according to the invention. 
         Fig.17  is a schematic exploded view of a modified embodiment of the instrument according to the invention. 
         FIG. 18  is a schematic drawing of a special application of a modified instrument according to the invention. 
         FIG. 19  is a schematic presentation of an unrolled view of a first embodiment of a flexible part of a cylindrical member as shown in  FIG. 1  or  2 . 
         FIG. 20  is an unrolled view of a second embodiment of a flexible part of a cylindrical member as shown in  FIG. 1  or  2 . 
         FIG. 21  is an unrolled view of a third embodiment of a flexible part of a cylindrical member as shown in  FIG. 1  or  2 . 
         FIG. 22  is a view of a flexible part as a guiding member between two longitudinal elements as shown in  FIGS. 14-16 . 
         FIG. 23  is a view of an embodiment of a flexible part as a guiding member as modified with respect to  FIG. 22 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In  FIG. 1  there is shown an axial cross-section of an instrument  1  according to the invention. The instrument  1  is composed of three coaxial cylindrical members: an inner member  2 , an intermediate member  3  and an outer member  4 . The inner cylindrical member  2  is composed of a first rigid end part  21 , which is the part normally used at the location which is difficult to reach or inside the human body, a first flexible part  22 , an intermediate rigid part  23 , a second flexible part  24  and a second rigid end part  25  which is normally used as the operating part of the instrument in that it serves to steer the other end of the unit. The outer cylindrical member  4  is in the same way composed of a first rigid part  41 , a flexible part  42 , an intermediate rigid part  43 , a second flexible part  44  and a second rigid part  45 . The length of the different parts of the cylindrical members  2  and  4  are substantially the same so that when the cylindrical member  2  is inserted into the cylindrical member  4 , the different parts are positioned against each other. The intermediate cylindrical member  3  also has a first rigid end part  31  and a second rigid end part  35  which in the assembled condition are located between the corresponding rigid parts  21 ,  41  and  25 ,  45  respectively of the two other cylindrical members. 
     From  FIG. 2  it will be clear to a person skilled in the art that a radial deflection of the handling end portion of the instrument  1  can be caused by a radial deflection of the actuating end portion of the instrument through a movement of the longitudinal elements  38  in a longitudinal direction.  FIG. 18  further illustrates this by the radial deflections of the handling end portions of the instruments  203  and  204  in response to the radial deflections of the actuating end portions of these instruments. 
     The intermediate part  33  of the intermediate cylindrical member  3  is formed by three or more separate longitudinal elements which can have different forms and shapes as will be explained below. After assembly of the three cylindrical members  2 ,  3  and  4  whereby the inner member  2  is inserted in the intermediate member  3  and the two combined members  2 ,  3  are inserted into the outer member  4 , the end faces of the three members  2 ,  3  and  4  are connected to each other at both ends so as to have one integral unit. 
     In the embodiment shown in  FIG. 2  the intermediate part  33  is formed by a number of longitudinal elements  38  with a uniform cross-section so that the intermediate part  33  has the general shape and form as shown in the unrolled condition in  FIG. 3 . From this it also becomes clear that the intermediate part is formed by a number of equally spaced parallel longitudinal elements  38  over the circumference of the cylindrical part  3 . The number of elements  38  must be at least three, so that the instrument  1  becomes fully controllable in any direction, but any higher number is possible as well. 
     The production of such an intermediate part is most conveniently done by injection molding or plating techniques or starting from a regular cylindrical tube with desired inner and outer diameters and removing these parts of the tube wall required to end up with the desired shape of the intermediate cylindrical member. This removal of material can be done by means of different techniques such as laser cutting, photochemical etching, deep pressing, conventional chipping techniques such as drilling or milling, high pressure water jet cutting systems or any suitable material removing process available. Preferably laser cutting is used as this allows a very accurate and clean removal of material under reasonable economic conditions. These are convenient ways the intermediate member  3  can be made in one process, without requiring additional steps for connecting the different parts of the intermediate cylindrical member as required in the conventional instruments, where the longitudinal members must be connected in some way to the end parts. 
     The same type of technology can be used for producing the inner and outer cylindrical members  2  and  4  with their respective flexible parts  22 ,  24 ,  42  and  44 . A tube having flexible parts can be obtained in different ways. In  FIGS. 19 ,  20 ,  21  and  22  there are shown different ways how such flexibility in the part can be obtained.  FIG. 19  shows a schematic representation of a rolled out flexible cylindrical portion. In the embodiment shown in  FIG. 19 , the part of the cylindrical tube to become flexible has been provided with slits  50  extending in a helical manner over the length of the flexible part. The flexibility can be controlled by the number of slits  50  and/or the angle of the slits  50  with respect to the axial direction of the cylindrical member. 
     In the embodiment of  FIG. 20 , the part of the cylindrical tube to become flexible has been provided with a number of short slits  51 . The slits  51  can be divided into groups, the slits  51  in each group being located in the same line extending perpendicular to the axis of the cylindrical member. The slits  51  in two neighboring groups are offset. In the embodiment of  FIG. 21 , the part of the cylindrical tube to become flexible has been provided by making slits producing a number of swallow&#39;s tails  52  which fit into each other as shown. 
     It will become obvious that other systems of providing a flexible part in a cylindrical tube wall may be used as well. More specifically, it is possible to use combinations of the systems described above. Otherwise, it will also become obvious that the advantageous process for producing such flexible parts in a cylindrical tube as described above may be used in the production of the intermediate part  33 . 
     As described above in the first embodiment, the longitudinal elements  38  are formed by a number of parallel elements equally spaced around the circumference of the cylindrical member  3 . As shown in  FIG. 3 , a free space is available between each pair of adjacent elements  38 . It is possible to use longitudinal elements  38  as shown in this figure, but in the flexible parts of the instrument there will be a tendency of the longitudinal elements  38  to move in a tangential direction especially when strong curves have to be made. As a consequence of this uncontrolled movement of the longitudinal elements  38 , the accuracy and the magnitude of the control of the position of the one end portion by the movement of the other end portion may be lost or become more complicated. This problem can be avoided by making longitudinal elements  38  in such a way that the free space between two adjacent elements  38  is as small as possible or completely left out so that two adjacent longitudinal elements  38  are touching each other and serve as a guide for each other. A disadvantage of this system however is that a large number of longitudinal elements  38  must be present, as the cross section of these elements must be chosen in such a way that their flexibility in any direction is almost the same independent of the direction of bending. As the wall thickness of the cylindrical member is relatively small compared to the overall dimensions of the cylindrical member especially with respect to the circumference, this will result in a large number of longitudinal elements  38  as seen along the tangential direction and an increase of total bending stiffness. As the longitudinal elements  38  are touching each other in the tangential direction, this provides for a guiding of these elements upon use of the instrument. 
     In a modified embodiment of the longitudinal elements this problem has been avoided in a different way. In this second embodiment shown in  FIG. 4  each longitudinal element  60  is composed of three portions  61 ,  62  and  63 , co-existing with the first flexible portion  22 ,  42 , the intermediate rigid portion  23 ,  43  and the second flexible portion  24 ,  44  respectively. In the portion  62  coinciding with the intermediate rigid portion, each pair of adjacent longitudinal elements  60  is touching each other in the tangential direction so that in fact only a narrow gap is present therebetween just sufficient to allow independent movement of each longitudinal element. 
     In the other two portions  61  and  63  each longitudinal element consists of a relatively small and flexible strip  64 ,  65  as seen in circumferential direction, so that there is a substantial gap between each pair of adjacent strips, and each strip  64 ,  65  is provided with a number of cams  66 , extending in circumferential direction and almost completely bridging the gap to the next strip. Because of these cams the tendency of the longitudinal elements in the flexible portions of the instrument to shift in circumferential direction is suppressed and the direction control is complete. The exact shape of these cams  66  is not very critical, provided they do not compromise flexibility of strips  64  and  65 . In view thereof, any shape like a trapezium shape as shown in  FIG. 4  is applicable. 
     In the embodiment shown in  FIG. 4 , the cams  66  are extending towards one direction as seen from the strip to which they are connected. It is however also possible to have these cams extending to both circumferential directions starting from one strip. By using this it is either possible to have an alternating type of strips as seen along the circumference, a first type provided at both sides with cams  66  extending until the next strip, or a second intermediate set of strips without cams. Otherwise it is possible to have strips with cams at both sides, where as seen along the longitudinal direction of the instrument the cams originating from one strip are alternating with cams originating from the adjacent strips. It is obvious that numerous alternatives are available. It is important that adjacent strips are in contact with each but that the flexibility of strips  64  and  65  is not compromised. 
     In  FIG. 5  there is shown a third embodiment of the longitudinal elements as may be used according to the invention. In this embodiment, the longitudinal elements  70  are formed by strips  71  comparable to the strips  38  of  FIG. 3  interconnecting the portions  31  and  33 . Furthermore, the strips  71  have been provided with cams  72  so that the strips  71  are almost comparable to the strips  61  or  63  of  FIG. 4 . In this way a guiding is provided by the cams  72  over the complete length of the strips  71 . It is obvious that in this case the modifications with respect to the position of the cams  72  and the alternating of strips  71  with cams on both sides and strips without cams as described above with respect to  FIG. 4  are also applicable for this embodiment. 
     In the fourth embodiment shown in  FIG. 6 , the longitudinal elements  80  are formed by strips  81  interconnecting the portions  31  and  35 . These strips are comparable to the strips  38  in  FIG. 3  and have substantially the same width. This means that between each pair of adjacent strips  81  there is left a circumferential gap  82 . Each gap  82  is filled substantially by means of another strip  83 , having a circumferential width slightly smaller than the circumferential width of the gap  82  and a longitudinal dimension which leaves some play between the ends of the axial ends of the strip  83  and the portions  31  and  35  respectively. The strip  85  is composed of three parts, a first flexible part  84 , schematically represented with dotted lines, an intermediate part  85  and a second flexible part  86 , the three parts coinciding with the flexible parts  22 , 42 , the intermediate parts  23 ,  43  and the flexible parts  24 ,  44  respectively of the instrument. The flexibility of the parts  84  and  86  may be obtained by any system described above, or as shown in  FIGS. 22 and 23 . The intermediate part  85  is connected to the strip  81 . In this way the strip  85  is guiding the movement of the strips  81  in the flexible portions of the instrument, without hindering their longitudinal movement. 
     In the embodiment shown, each strip  81  is on one side connected to a strip  83 . As an alternative it is also possible to have a system in which as seen along the circumference of the intermediate cylindrical member this member is composed of a first set of strips  81  having both sides connected to a strip  83 , and a second set of strips  81  which have no connection to such strips  83  and are as such comparable to the strips  38  of  FIG. 3 . It is of course obvious that other solutions are available by using combinations of strips  81  having either no, one or two connections to strips  83  by putting them in the right sequence along the circumference of the intermediate cylindrical member. 
     A fifth embodiment has been shown in  FIG. 7 . In this embodiment, each longitudinal element  90  is composed of a first strip  91 , a band  92  and a second strip  93 . The first and second strips  91  and  93  each have a circumferential width such that there is a circumferential gap  94  and  95  respectively between each pair of adjacent strips  91  and  93  respectively. The bands  92  have a circumferential width such that two adjacent bands are in contact with each other. The strips  91  and  93  coincide with the flexible portions  22 ,  42  and  24  and  44  respectively whereas the bands  92  coincide with the intermediate portion  23 ,  43 . In each gap  94  and  95  respectively, plates  96  and  97  are placed which plates  96 ,  97  have a circumferential width filling the width of the gap  94 ,  95  and thus providing a guiding for the strips  91  and  93  respectively. Free movement of the strips is achieved in that in the longitudinal direction there is some play between the axial ends of the plates  96 ,  97  and the portion  31 , the bands  92  and the portion  35  respectively. 
     The plates  96 ,  97  are completely free to move in their respective gaps  94 ,  95  respectively, but because of the selected dimensions only a movement in longitudinal direction is available. For the production of such a system as shown in  FIG. 7  it is possible to first make the intermediate cylindrical elements by means of one of the production techniques described above, which results in an intermediate cylindrical member which is different from the one shown in  FIG. 7  in that one point of each plate  96  and  97  is still connected either to an adjacent strip, to a band, or to the portions  31  or  35 . In this form, the instrument is assembled whereby the connection point between the plates  96  or  97  and the remainder of the intermediate cylindrical member coincides with a hole provided in the cylindrical member  4 . Once the assembling is finished, the connection mentioned above can be destroyed, for example by using one of the production techniques mentioned above. In this way, the plates  96 ,  97  become completely freely movable in their gaps. Here once more it will become obvious that the laser technology is very effective in this production step. 
     In  FIG. 8 , there is shown a sixth embodiment of the intermediate cylindrical member according to the invention. This embodiment is very similar to the embodiment shown in  FIG. 7 , in that the longitudinal elements  100  are composed of strips  101  and  103  comparable to the strips  91  and  93 , and a band  102  comparable to the band  92 . In the same way, the gaps  104  and  105  are comparable to the gaps  94  and  95 , and are occupied by plates  106  and  107 , which are comparable to the plates  96  and  97 . In this embodiment, the plates  106  and  107  are not completely free from the remainder of the instrument, but each plate  106  and  107  is connected either to the outer cylindrical member  4  or to the inner cylindrical member  2 , especially in the non-flexible part thereof. In the embodiment shown, this is achieved by welding at one point,  108  and  109  respectively, the plates  106  and  107  to the intermediate rigid portion of either the inner or outer cylindrical member  2  or  4 . In this way, the strips  101  and  103  are accurately guided by the plates  106  and  107  in the flexible portions of the instrument, but the plates  106  and  107  are not free to move whereby the control of movement is improved and the assembling of the instrument becomes much easier. 
     The seventh embodiment, shown in  FIG. 9  can be seen as a combination of the embodiment of  FIG. 6  and the embodiment of  FIG. 8 . The longitudinal element  110  consists of a number of strips  111 , comparable to the strips  81  and the gap  112  between each pair of adjacent strips  111  is occupied by a strip or plate  113  comparable to strip  83 . In this embodiment the strips  113  are not connected to the strips  111  as in the embodiment of  FIG. 6 , but are connected at some points  115 ,  116  to the rigid intermediate part of either the outer or inner cylindrical member  2  or  4  of the instrument comparable to the embodiment of  FIG. 8 . 
     In  FIGS. 10 ,  11 ,  12  and  13  there is shown an embodiment of the instrument which can be seen as a modification of the embodiment shown in  FIG. 9 . In  FIGS. 10 and 11  there is shown a situation before assembly whereas  FIGS. 12 and 13  show the assembled instrument. 
     In  FIGS. 10 and 11  there is shown the outer cylindrical element  4 , which is composed of three parts, a part  121  forming the first flexible portion  42  and the first rigid portion  41 , a part  122  forming the intermediate rigid portion  43  and also forming the guiding plates  124  comparable to the guiding plates  106 ,  107  in  FIG. 8  and a part  123  forming the second flexible part  44  and the second rigid part  45 . 
     The parts  121  and  123  are simple cylindrical tubes which have been provided with a flexible portion by one of the methods described above. The intermediate portion  122  is formed by a cylindrical tube in which, by one of the processes described above for removal of material, a number of tongues  124  have been made flexible by one of the methods described above. These tongues extend from both ends of a central portion and form bands which occupy the space between strips like the strips  111 . Therefore the tongues are deformed at their connection with the central portion  125  so as to have a smaller diameter whereby these tongues fit into the spaces between the strips. In fact the tongues are deformed to form internal and external diameters substantially equal to the corresponding diameters of the strips. 
     After the different parts  121 ,  122  and  123  are produced as described, the parts  121  and  123  are moved over the tongues  124  and the respective abutting ends of the parts  121  and  123  are welded to the central portion  125  so as to form the external cylindrical member  4 . 
     In  FIGS. 14 ,  15  and  16  there is shown a different category of embodiments of longitudinal elements  130  interconnecting the portions  31  and  35  of the intermediate cylindrical member  3 . The longitudinal elements  130  are formed by strips  131  comparable to the strips  38  of  FIG. 3 . As seen in the circumferential direction of the cylindrical member, these strips are spaced apart from each other by a gap  132 . At least in the flexible zone of the instrument where a guiding of the strips is preferred or required, each pair of adjacent strips is connected by a number of bridges which have a defined degree of flexibility as seen in the longitudinal direction. These bridges extend the width of the gap  132  and can be shaped in different ways. 
     In the embodiment of  FIG. 14 , the bridges have the form of short strips  134  extending in the circumferential direction and having a width in the longitudinal direction which allows some parallel movement from one strip  131  to an adjacent strip  131 . By selection of the number of short strips  134  and the cross-sectional dimensions thereof, the flexibility of the short strips  134  may be sufficient to allow sufficient freedom of movement of the adjacent strips  131 . If needed, the flexibility of the short strips  134  can be enhanced by applying some special configurations as shown in  FIGS. 23 ,  24  and  25 . The short strips  134  need not transfer any tangential force from one strip  131  to the adjacent strip  131 , but serve only to maintain the distance between two adjacent strips  131 . 
     In the embodiment shown in  FIG. 15 , the strips  135  are shaped with some recesses so as to increase their flexibility. Moreover these strips  135  have been not directed along the circumferential direction of the cylindrical member, but are positioned under a small angle with respect to the circumferential direction in a way that the series of connectors form a spiral. A special shape of the bridges is shown in the embodiment of  FIG. 16 . The bridges  136  of this embodiment consist of two cams  137  and  138  extending from two adjacent strips  131  and abutting about halfway in the gap between the two strips. Two semicircular bands  139  and  140  connect the two cams  137  and  138 . This provides a high degree of flexibility while the distance between the two adjacent strips is accurately maintained. The making of such bridges  136  does not present any special problems when using one of the techniques described above. 
     In  FIG. 17 , there is shown a special embodiment of an instrument according to the inventions. The inner cylindrical member is composed of a first rigid end part  141 , a first flexible part  142 , an intermediate rigid part  143 , a second flexible part  144  and a second rigid end part  145  which is normally used as the operating part of the instrument in that it serves to steer the other end of the unit. The outer cylindrical member is in the same way composed of a first rigid part  161 , a flexible part  162 , an intermediate rigid part  163 , a second flexible part  164  and a second rigid part  165 . The intermediate cylindrical member also has a first rigid end part  151  and a second rigid end part  155  which in the assembled condition are located between the corresponding rigid parts  141 ,  161  and  145 ,  165  respectively of the two other cylindrical members. In the embodiment shown the longitudinal elements  153  are of the type shown in  FIG. 3 , but it will become obvious that any other type described above may be used as well. So far the construction is comparable to the instrument shown in  FIG. 1 . 
     The main difference with respect to the embodiment of  FIG. 1  consists in the use of a different set of diameters for some parts of the instrument. In the embodiment shown, the parts  144 ,  145 ,  155 ,  164  and  165  have a larger diameter than the other parts and in the parts  143 ,  153  and  163  a frusto-conical portion is formed in order to connect the smaller diameter parts with the larger diameter parts. As shown in  FIG. 17 , the different parts can easily be assembled by inserting one into the other. The main reason however to have such an instrument with different diameters is that by using an operating part with a larger diameter, the movement of the other end is amplified, whereas if a smaller diameter is used the movement of the other end is reduced. Depending on the application and its requirements, larger diameters can be used to provide the amplified movement or smaller diameters can be used to reduce the movement and increase accuracy. 
     A special application of the instrument according to the invention is shown in  FIG. 18 . In this application, a number of tubes have been inserted into a body of an environment where some inspection or treatment must take place. In the embodiment shown there are three tubes including a first or central tube  200 , which may be a straight tube which is used for illumination and viewing purposes. Two S-shaped tubes  201  and  202  are positioned partly against this central tube  200 , and these tubes are used for the guiding of instruments  203  and  204  according to the invention. The bending is necessary to have the handling side of the instruments  203  and  204  removed from each other and from the central tube  200  so that the movement is possible in any direction. By positioning the S-shaped tubes diametrically in opposition to the central tube  200 , there is also sufficient space left at the working side to perform all kinds of movement of these ends of the instruments  203  and  204 . 
     In order to enable the instruments to be guided through such an S-shaped tube  201  or  202  or a tube with any curved shape, the intermediate rigid portion of the instruments  203  and  204  is provided with at least one additional flexible portion dividing the intermediate portion in rigid portions of a lesser length so as to allow some additional bending. If needed, more than one intermediate flexible portion may be included. 
     It is obvious that the invention is not restricted to the described embodiments as shown in the attached drawings, but that within the scope of the claims modifications can be applied without departing from the inventive concept.