fig1 illustrates , in a perspective view , a flexible tube 10 near the distal end 12 of an endoscope device incorporating the invention . the tube 10 may be curved in a desired direction or made rigid when appropriate . the construction thus permits adjustment of rigidity as well as curvature . that is , if the tube is too flexible , then it cannot be easily guided into a body cavity . if it is too stiff , then it cannot comfortably be directed through curved body cavities or canals . thus , the present invention seeks to provide an endoscope tube wherein the stiffness of the tube is adjustable , and the curvature is also adjustable in order to most efficiently guide the tube through curved cavities or canals . in the drawings , therefore , the flexible tube 10 of the endoscope is depicted the instrument or proximal end of the endoscope is not depicted but may be of any construction known to those of ordinary skill in the art depending upon the particular medical or diagnostic instrument involved . typically , the endoscope tube 10 has a hollow elongate passage 22 including , for example , a fiber optic member which extends the length of the tube 10 to provide not only a light source path but also a transmission lens . the fiber optic element thus connects with appropriate instruments at the proximal end of the instrument , as shown in the prior art references previously identified , for the purpose of permitting a visual diagnosis . in some instances , medical instruments are inserted into the passage 22 of tube 10 to provide for the taking of a biopsy , for example , or for other surgical or diagnostic purposes . the tube 10 is preferably elastic . the flexible tube 10 is comprised of a series of connected segments 14 . each segment 14 has approximately the same dimensions in length and diameter and constitutes a continuous portion of the tube 10 , although the dimensions of each segment 14 need not be identical . each segment 14 is independently controlled insofar as stiffness and curvature by separate control means in the manner to be described below . fig2 illustrates a benefit that results from having each of the segments 14 independently controlled to provide , for example , a controlled amount of stiffness as well as curvature . thus , the ultimate end segment l4a may be curved upwardly . the next adjacent segment l4b may be rigid and straight , and the next segment l4c may be curved downwardly . referring to fig3 and subsequent figures , the construction and operation of the individual segments 14 is described by reference to the end segment l4a near the distal end 12 of the endoscope . segment l4a has a centerline axis 16 . a plurality of four specially constructed conduits 18 , 19 , 20 and 21 extend parallel to the longitudinal axis 16 within segment l4a . each conduit 18 , 19 , 20 , 21 is positioned at an equal radial distance from the axis 16 and is equally spaced on a cylindrical locus from one of the other conduits 18 , 19 , 20 , 21 . the interior part of the segment l4a is , in the preferred embodiment , hollow defining the hollow tubular passage 22 for receipt of an instrument o a fiber optic package as previously described . the instrument package or fiber optic package or the like , which is retained within the passage 22 , is plastic , i . e . it assumes the curvature of segment l4a . each of the conduits 18 , 19 , 20 and 21 has a similar construction . that is , each conduit 18 , 19 , 20 , 21 is generally tubular and is comprised of an elastic material having an accordion configuration or cross section , as depicted in fig5 when the segment 14 is in a relaxed condition . that is , the cross sectional configuration of the conduit 21 is such that folds 23 , defining the conduit 21 , are not extended or elongated when the conduit 21 is not elastically stressed or is relaxed . further , each of the conduits 18 , 19 , 20 and 21 is closed or sealed at its distal end , e . g . end l9b . the opposite end , e . g . end l9c , is connected to a pressure source , for example , a gas or liquid pressure source . admission of pressurized gas to a first pressure level within the conduits 18 , 19 , 20 and 21 will tend to cause the conduits 18 , 19 , 20 , 21 to become rigid . this , in turn , will make the segment l4a rigid inasmuch as it is reinforced by the four parallel , inflated conduits 18 , 19 , 20 , 21 . in order to make the segment l4a rigid . the pressure in each of the conduits 18 , 19 , 20 and 21 should be maintained equal . further , in such instance the pressure in each of the conduits 18 , 19 , 20 , 21 should preferably be at a level which will not cause the conduits 18 , 19 , 20 , 21 to expand in the direction of the longitudinal axis 16 . in order to effect curvature of the segment l4a , differential pressures are provied to the conduits 18 , 19 , 20 and 21 . for example , referring to fig5 pressure in the conduit 19 is increased and pressure in the conduit 21 is maintained at an ambient pressure or decreased relative that in conduit 19 in order to cause curvature of the segment l4a . thus , the conduit 19 is pressurized a sufficient amount to cause the conduit 19 to , in essence , elastically elongate or extend axially . simultaneously the pressure in the conduit 21 may be maintained at an ambient level . alternatively , a vacuum or a partial vacuum may be provided within the conduit 21 . this will cause the segment l4a , which receives the conduit 21 , to assume an arcuate or curved shape as depicted . curvature of segment 14a results since the conduit 19 becomes elongated and the conduit 21 remains the same length or foreshortens . to insure such curvature , the opposite ends of each conduit 18 , 19 , 20 , 21 are preferably fixed to the segment l4a whereas the portion of the conduits 18 - 21 intermediate the ends is not fixed to the segment l4a , but rather rides in a passage in segment l4a . for example , conduit 19 is fixed to segment l4a at conduit ends l9b and l9c . intermediate the ends l9b and l9c , the conduit 19 is slidable in a passage in segment l4a . the conduit 19 , when initially inflated will thus become rigid and maintain a length equal to the original spacing of ends l9a and l9b . as the pressure in conduit 19 increases beyond a threshold elastic pressure lmmit , the conduit 19 elongates thereby elongating one side of the segment l4a . segment l4a is thus somewhat elastic so as to respond to the elongation resulting when the conduit 19 is inflated and elongated . curvature in any direction can be effected by increasing the pressure in the manner described in any one or two of the four conduits , 18 , 19 , 20 or 21 . by providing variable increased pressure to combinations of adjacent conduits , it is possible to effect highly controlled curvature of the segment l4a . note that each of the conduits 18 , 19 , 20 and 21 is elastic . thus , when pressure that causes elastic elongation of a conduit 18 - 21 is removed from the conduit 18 , 19 , 20 or 21 , the conduit 18 , 19 , 20 or 21 will resume its original shape . the segment l4a thus , being slightly elastic , responds to the pressure pattern imparted by the elastic conduits 18 , 19 , 20 and 21 . in practice , four conduits 18 , 19 , 20 , 21 provide sufficient means for control of curvature of each segment 14 . however , additional conduits may be provided in a radially spaced pattern about the centerline axis 16 in order to further enhance the control of the endoscope segment 14 . further , in practice each endoscope segment 14 includes its own separate set of conduits which are elastic and expandible in the manner described . in this manner each segment 14 of the endoscope is separately controllable in terms of rigidity as well as curvature . fig6 , 8 and 9 illustrate a type of pressure control device which may be used to control pressure in conduits 18 - 21 and thus the rigidity and curvature of the segment 14 . as shown in fig6 and 7 , the conduits 18 , 19 , 20 and 21 connect to a control box 28 having a control lever 30 pivotally mounted on a bearing 32 in a seat 34 in a throughbore in a plate 33 within the housing 28 . plate 33 separates the housing 28 into a high pressure chamber 62 and a low pressure chamber 64 . suitable , variable pressure sources 61 , 63 are attached to chambers 62 , 64 , respectively . the lever 30 includes a rigid , hollow cylindrical rod 36 which supports a valve actuator 38 . the end of the rod 36 is connected with the bearing 32 . in this manner the rod 36 is pivotal so as to permit the actuator 38 to engage either valve 40 or 42 , for example , associated with conduits 18 and 20 , respectively . the valves 40 and 42 are spring biased by associated springs 44 and 46 to the closed position until one of them is actuated by the actuator 38 due to pivoting of the rod 36 . when in the closed position , valves 40 , 42 are positioned to vent associated conduits 18 , 20 to atmosphere via vent passages 41 , 43 . the hollow rod 36 includes a telescopically received , flexible rod 48 supporting a second actuator 50 . the rod 48 may be telescopically extended to the position shown in fig9 by means of a lever 52 which can be positioned in a lower notch 53 rather than an upper notch 55 defined in hollow rod 36 . thus , the actuator 50 may be positioned for simultaneous engagement or disengagement with valves 54 and 56 which are normally closed due to actuation of associated springs 58 and 60 . the valves 54 and 56 are associated respectively with the conduits l8a and 20a in fig6 . conduits l8a , 20a are vented to atmosphere via vents 55 , 57 when valves 54 , 56 are closed . the operation of the controls will be described with respect to the conduits 18 and 20 . to control rigidity only , pressure from chamber 64 is provided via all conduits l8a , 20a ( also l9a , 2la ) simultaneously . thus , the lever 52 is in the position illustrated in fig9 in a lower notch 53 rather than an upper notch 55 of rod 36 . the actuator 50 thus will simultaneously engage the ball valves 54 , 56 thereby providing low pressure through conduits l8a , 20a through check valves 70 to the conduits 18 , 20 . when controlling rigidity in this manner , the lever 30 is maintained in a neutral or center rest position . to control curvature , the control lever 30 may be actuated by movement in any direction to thereby effect high pressure flow to any of the conduits 18 , 19 , 20 or 21 . thus , in order to effect curvature associated with elastic pressurization of the conduits 18 , the lever assembly 30 is pivoted in a counterclockwise sense as illustrated in fig9 to open ball valve 42 . this closes vent 43 and imparts high pressure from the chamber 62 through the valve 42 to the line 20 . no simultaneous pressure is provided to the conduit 18 . the high pressure in conduit 20 actuates check valve 70 in fig7 to permit fluid flow to the conduit 20 in segment 14 . this results since pressure in chamber 62 exceeds pressure in chamber 64 causing valve 70 to switch to the high pressure source . to effect the opposite curvature , the lever assembly 30 is pivoted in the clockwise direction . this actuates the ball valve 40 and closes vent 41 . valve 42 closes and vent 43 opens . conduits 19 and 21 are similarly controlled with respect to the use of ball valves and the like . in this manner it is possible to effect complete control of the rigidity and curvature of a segment of the endoscope tube 10 . such a lever assembly is typically provided for each segment 14 of the endoscope . in practice , only one or two lever assemblies need to be utilized inasmuch as only one or two segments 14 will be needed in order to guide an endoscope tube 10 appropriately into position . the pressure in the chamber 64 is also preferably variable in order to adjust the rigidity of the segments 14 as determined by the pressure within each of the separate conduits 18 - 21 . in sum , lever 30 controls curvature . flexible rod 52 controls rigidity . rigidity requires low pressure relative to the higher pressure curvature control . it is possible to vary the construction of the invention in numerous ways . for example , each of the separate segments l4a , l4b and l4c may be connected to a separate control mechanism for purposes of controlling rigidity . each of the separate control mechanisms can be adjustable to provide various levels of pressurization of that separate segment . with increased pressurization of a segment , there is increased rigidity . it is also possible to interconnect the conduits 18 - 21 of separate segments l4a - l4c by means of threshold check valves . thus , the segments l4a - l4c will be sequentially pressurized as increasing thresholds of pressure are reached . yet a further alternative construction would provide for use of a single control mechanism which could connect to any one of the separate segments l4a , l4b , l4c , etc . the connection to each of the separate segments l4a , l4b , l4c , etc . is controlled by a selector switch . as a further feature of the invention , an elastic distal end segment may connect to one or more of the conduits 18 - 21 . the distal end segment can then be inflated and function as a dilator to help advance movement of the endoscope into a body canal or cavity . further , the invention can be constructed so that the conduits 18 - 21 are always equally pressurized to merely provide a means to render the segments 14 rigid . also , separate means such as known to those of ordinary skill in the art can be used to control the curvature of the segments 14 or tube 10 . for example , it is known to use various wire control systems which mechanically operate to curve the tube 10 . such a mechanical system can be used in combination with the conduit system of the present invention . yet another option is to provide alternate means for venting the conduits 18 - 21 whenever the associated valve connecting that conduit to a pressure source is released . it is also possible to vary the construction of the conduits . that is , an accordion - type cross section has been disclosed . however , the cross sectional shape , size and configuration of the conduits , for example conduit 18 , may be varied in accord with desires to achieve various types of control upon inflation as well as upon the elastic deformation . further , the number of conduits used in each segment may be varied . the number of control segments can be varied . the particular arrangement of the conduits relative to the center line axis of the tube can be varied . the choice of materials can be varied . the interconnection or interrelationship of the conduits 18 - 21 to the tube 10 can be varied . the conduits may be , for example , integrally molded or formed in the tube 10 . alternatively , the conduits may be made of a separate material having distinct elastic and plastic characteristics relative to the material used to form the tube 10 . though a toggle stick or joy stick mechanism for controlling pressure to each of the separate conduits is disclosed , numerous other types of control mechanisms are possible to vary the pressure to each of the separate conduits in each of the separate segments . thus , while there has been set forth a preferred embodiment of the invention , it is to be understood that the invention is to be limited only by the following claims and their equivalents .
an improved flexible endoscope of the type which includes a hollow elongate flexible tube having a distal end which is inserted into a body cavity and a proximal end which is external the body . a sensor system extends through the flexible tube from the proximal end to the distal end . the sensor system is capable of transmitting diagnostic information from the distal end to a sensor system at the proximal end . means for controlling the flexure of each tube comprises at least one longitudinal expandible conduit positioned radially with respect to the center line axis of the segment . in a preferred embodiment a plurality of inflatable and expandible conduits are provided and pressure means is also provided to inflate the conduits to control rigidity or to expand the conduits longitudinally and sequentially in order to vary the curvature of the tube .