with reference to fig1 , it has been generally indicated at 1 an endoscopic device according to the present invention . it comprises an intermediate section 1 a of a tubular shape , extending between two end sections called front end section 1 b and rear end section 1 c , the terms “ front ” and “ rear ” being referred to a reference direction indicated at a . clearly , the endoscopic device will be able to move in the body cavity in a forward and a backward direction . the tubular intermediate section 1 a is formed by a wall 2 made of elastic and flexible material shaped like a bellows and delimiting a cavity 3 for containing a fluid , for example air . the intermediate section ends with a front flange 2 a and a rear flange 2 b through which it is connected to front end section 1 b and rear end section 1 c respectively . front end section 1 b of the device is formed by a stem 4 fixed to front flange 2 a at a flanged end 4 a thereof and to a front head 5 of the device at the other end . fixed to flanged end 4 a of stem 4 , at the opposite side of flange 2 a , is a bellows member 6 which is integral to a jaw 7 a of a first clamp 7 ( also called front clamp ) slidably mounted on stem 4 and fixed to the free end of bellows 6 . the other jaw 7 b of first clamp 7 is constituted by a face of front head 5 perpendicular to the axis of stem 4 and faced toward first jaw 7 a . rear end section 1 c is formed by a rear head 8 , from which a tubular connector 9 extends , connected to a flanged end 10 a of a stem 10 . fixed to flanged end 10 a , at the opposite side of rear head 8 , is a bellows member 11 integral to a jaw 12 a of a second clamp 12 ( also called rear clamp ) coaxially and slidably mounted on stem 10 , the other jaw 12 b of second clamp 12 being formed by a plate fixed to the end of stem 10 at one side thereof and to rear flange 2 b of intermediate section 1 a at the other side . tubular connector 9 puts into communication the device with an external control system , of the conventional type , for example as described and shown in fig3 of u . s . pat . no . 5 , 906 , 591 , comprising a source ( 50 ) for selectively providing a positive or negative pressure to the various parts of the devices as will be explained below . more precisely , connector 9 houses pneumatic conduits extending in a substantially axial way within device 1 ( as schematically shown in fig1 ), each of them being able to both feed compressed air to and suck air from chamber 3 of bellows - shaped intermediate section 1 a ( conduit 40 ), bellows member 6 and 11 controlling the operation of clamps 7 and 12 ( conduits 41 , 42 ), as well as to / from a surface portion of stems 4 and 10 comprised between jaws 7 a , 7 b and 12 a , 12 b , respectively , of clamps 7 and 12 , through diametral ducts 13 and 14 extending from respective axial ducts 15 and 16 formed in stems 4 and 10 , communicating with respective pneumatic conduits housed within connector 9 . a further pneumatic conduit . 43 outflows from front head 5 to blow air jets useful to assisting forward motion of the device . in particular , pneumatic conduits passing through intermediate section 1 a are helically arranged within chamber 3 as schematically indicated at 44 in fig1 . the operating cycle of the endoscopic device is now described with reference also to fig2 a - 2 k ( the parts being in turn under pressure are shown as hatched ). by creating suction conditions at rear clamp 12 a substantially annular portion p of the surrounding wall of the body cavity is caused to collapse between jaws 12 a , b which , by adduction of compressed air within bellows 11 , close against each other firmly grasping wall portion p ( fig2 a ). through radial duct 13 of stem 4 air is blown against cavity wall p to cause its displacement from front end section 1 b of the device ( fig2 b ). then compressed air is fed to bellows 2 which elongates pushing front end section 1 b of the device forward ( fig2 c ). at this point , a depression is created between jaws 7 a , b of front clamp 7 which causes a substantially annular portion of the surrounding cavity wall p to collapse therebetween . by adducting compressed air bellows 6 is caused to elongate and clamp 7 closes firmly grasping cavity wall ( fig2 e ). bellows 11 is then retracted by depression to open clamp 12 ( fig2 f ) releasing the grasped cavity wall which is displaced back from rear end section 1 c of the device by means of air jets through radial duct 14 of stem 10 ( fig2 g ). rear end section 1 c is then pulled forward by bellows 2 which retracts due to depression induced therein ( fig2 h ). at this point , rear clamp 12 grasp a new annular portion of surrounding cavity wall p by creation of a depression between jaws 12 a , 12 b ( fig2 i ) and closure of rear clamp 12 ( fig2 j ), while front clamp 7 opens to release the grasped annular wall portion . then the cycle is repeated with a new advancement step . in order to improve the grip of jaws 7 a , 7 b and 12 a , 12 b of front clamp 7 and rear clamp 12 respectively , a circular groove 17 is formed on one of their opposed faces and a corresponding step 18 for engaging with groove 17 is formed on the other face . advantageously all the edges of the grip surfaces are beveled to avoid any tissue damage . a second embodiment of the endoscopic device according to the invention is shown in fig3 , 4 , 5 , 6 a - c and 7 a , b . in the figures , 21 a indicates an intermediate tubular section of the device formed by a bellows wall 22 made of elastic and flexible material delimiting a chamber 23 , 21 b indicates a front end section connected to intermediate section 21 a through a front flange 22 a and 21 c indicates a rear end section connected to intermediate section 21 a through a rear flange 22 b . front end section 21 b comprises a head 25 conected to front flange 22 a and integral to a stem 24 axially extending through intermediate section 21 a and rear end section 21 c and connected to a tubular connector 29 . a first clamp 27 is mounted at the end of stem 24 opposite to that where head 25 is fixed . each clamp is formed by a jaw 27 a axially slidable on stem 24 and by a jaw 27 b fixedly connected thereto . jaw 27 a and 27 b are each formed by a pair of jaw portions diametrically arranged on stem 24 . the two portions of jaw 27 a are mutually connected by means of a bracket 28 passing through a slot 30 diametrically formed in stem 24 . an actuating wire 26 crosses bracket 28 in two points and is fixed to the bracket at one of them while being slidable at the other one . wire 26 slidably extends through the overall length of stem 24 forming a loop along it and its free ends are conveyed externally through connector 29 . clearly , by pulling one of the two ends from the outside , the opening and closure of clamp 27 can be controlled , as also shown in fig7 a and 7 b . as shown in fig6 a , b , c , rear end section 21 c of the device comprises a first sleeve 33 coaxially mounted on stem 24 and slidable thereon . sleeve 33 has a flanged end one side of which is fixed to rear flange 22 b of intermediate section 21 a , the other one being fixed to a bellow 31 coaxial thereto . a pair of arm 33 a , 33 b extend from sleeve 33 in a diametrically opposed and parallel relationship with respect to stem 24 . arms 33 a , 33 b are arranged on a plane rotated of an angle of 90 ° with respect to the two jaw portions of first clamp 27 and support jaws 32 a and 32 b of second clamp 32 . likewise first clamp 27 , second clamp 32 is formed by two diametrically opposed clamp portions and therefore clamps 27 and 32 are in a substantially crosswise arrangement with respect to the longitudinal axis of the device , as shown in fig4 . in particular , the pair of portions of jaw 32 a are fixed to the free ends of arms 33 a and 33 b , while the pair of portions of mobile jaw 32 b are formed at the end of two further arms 34 a and 34 b extending at the outside of arms 33 a and 33 b and parallel thereto from a second sleeve 34 integral to bellow 31 and axially slidable on sleeve 33 . the sliding of arms 34 a , b with respect to arms 33 a , b is limited at one side by the abutment with fixed jaw 32 a and at the other side by the mutual abutment between shoulders 35 and 36 formed on the respective sliding surfaces . tubular connector 29 houses a plurality of pneumatic tubes communicating to a series of conduits formed in stem 24 . in particular , with reference to fig3 , conduits 37 and 38 are provided for creating a depression or feeding compressed air between jaws 27 a , b of first clamp 27 and jaws 32 a , b of second clamp 32 , to help engagement and , respectively , release of the surrounding wall portion p of the body cavity , and conduits 45 and 46 to suck or feed air from / to bellows 31 and 22 , thereby causing them to extend and respectively to retract . a conduit for feeding air to head 25 is also provided to blow air against the cavity wall during the forward motion . these conduits are all shown in fig3 for sake of simplicity . conduits 38 and 45 are helically arranged inside chamber 23 . the operating cycle of the endoscopic device according to the second embodiment of the invention is shown in fig8 a - 8 g . first , vacuum is created in correspondence of the jaws of second camp 32 to cause a surrounding wall portion p of the body cavity to collapse therebetween ( fig8 a ), then compressed air is entered in bellows 31 which in this way is elongated causing the closure of second clamp 32 and the grasping of wall portion p ( fig8 b ). compressed air is entered in chamber 23 of bellows 22 which expands pushing front head 25 forward . in view of the connection through stem 24 front head 25 pull first clamp 27 forward ( fig8 c ) after having created a depression between the jaws of first clamp 27 to make the surrounding wall portion p to collapse therebetween , first clamp 27 is closed by traction of actuating wire 26 to grasp wall portion p ( fig8 d ). at this point second clamp 32 can be opened by sucking air from bellow 31 , to release the wall portion p held thereby ( fig8 e ). once second clamp 32 is opened , it is made to advance with respect to first clamp 27 by sucking air from bellow 22 , which retracts ( fig8 f ). in these conditions , after second clamp 32 is held again to the body cavity wall , first clamp 27 is opened and the cycle repeated for a further advancement step . opposed grip surfaces of jaws of first and second clamp 27 and 32 are formed with an annular groove and a corresponding step for engaging therewith to improve the grip of the wall portion of the body cavity . it will be appreciated that in the second embodiment of the invention clamps 27 and 32 alternately overtake each other during each advancement step of the device and the clamp that in turn is in the distal position is the gripping one , while the other one is free and is pulled forward . this prevents the body cavity wall , due to its easily yielding nature , from retracting into folds together with the device in the retraction step and extending in the next extension step without achieving any real forward motion of the device . from the foregoing it is clear that the endoscopic device according to the invention can migrate through a body cavity of tubular shape apart from the consistency of the walls and the friction that can be afforded by them , because it is able to grasp at the cavity wall before exerting its propulsive push . the increased patient &# 39 ; s comfort and the reduction of manual handling made possible with the device of the invention could promote the possibility of mass screening the population for gasto - itnestinal aliments , in particular to carry out colonoscopy and rectosigmoidoscopy , this being a particularly important inspection , in so far as about 70 % of the colon cancers are localized in the first tract or the colon . in addition to inspection and diagnosis , future integration of miniaturized endoscopic tools onboard the locomotive device would allow therapeutic procedures to be performed as well . several variations may be brought to the above described endoscopic device . front and rear end sections can be removably connected to the intermediate section so as to be easily replaced in case of damage , for example due to clogging by pollutants , or for maintenance . the wall of the intermediate section can be constituted by an elastically extensible smooth tube instead of a bellows . the device could be made with disposable plastic materials , provided that they are suitable for insertion in a body cavity . even if in the present embodiments of the invention pneumatically actuated bellows means have been provided for controlling the extension and the retraction of the intermediate section and the opening and closing of the clamping means , it is clear that , as an alternative , any equivalent linear actuating means such as elastic means or minimotors , can be used . likewise , compressed air distribution can be carried out in a different way from what has been illustrated , for example by using microvalves within the device , possibly controlled with shape memory alloy actuators . further variations and / or modifications can be brought to the endoscopic device according to the present invention , without departing from the scope of the invention as set forth in the attached claims .
an endoscopic device for locomotion in a body cavity according to a prefixed advancing direction comprising at least a variable length intermediate section extending between a front end section and a rear end section . first and second clamping means are integral to the front and rear section , for alternately grasping respective surrounding portions of wall of the body cavity . sucking means are associated to the first and second clamping means for creating a depression sufficient to cause the body cavity wall portions to collapse within the first and second clamping means while they are in an open condition . means for actuating alternate extensions and retractions of the intermediate section and actuating means of the first and second clamping means are further provides for synchronous operation to generate a forward motion of the rear end section due to a retraction of the intermediate section , the wall portion surrounding the first clamping means being firmly held therebetween , and to generate a forward motion of the front end section due to an extension of the intermediate section , the wall portion surrounding the second clamping means being firmly held therebetween .