CONDITION CHECKING DEVICE FOR ENDOSCOPE

An endoscope system includes an endoscope, having a tip device for entry in a body cavity, and a viewing window portion formed in the tip device. A sleeve-shaped condition checking device is disposed on a distal side in an axial direction, for resiliently deforming in a transverse direction crosswise to the axial direction when pushed on an inner wall of the body cavity, to enter a viewing area of the viewing window portion. Furthermore, a propulsion assembly constitutes the condition checking device, and exerts force of propulsion to the tip device, for assistance to entry in the body cavity. The condition checking device includes a resilient end ring, disposed distally of a support sleeve, covered by a propulsion assembly, and having a tapered wall of which a diameter decreases in the axial direction from the support sleeve.

InFIGS. 1 and 2, an endoscope2for a medical use includes an elongated tube3, a handle4and a universal cable9. The elongated tube3is entered in a body cavity of a patient, such as a large intestine of a gastrointestinal tract. The handle4is used for holding the endoscope2and manipulating the elongated tube3. The universal cable9connects the endoscope2to a processing apparatus5, a light source apparatus6and a fluid supply source8. The fluid supply source8is constituted by a pump8afor supplying air, and a water reservoir8bor tank. The pump8ais a well-known device incorporated in the light source apparatus6. The water reservoir8bis disposed outside the light source apparatus6, and stores water for washing.

The elongated tube3includes a tip device3a, a steering device3band a flexible device3c. The tip device3ais rigid and includes an imaging unit to be described later. The steering device3bextends to a proximal end of the tip device3aand steerable up and down and to the right and left. The flexible device3cis disposed between the steering device3band the handle4.

The tip device3aof the elongated tube3includes a viewing window portion10, lighting window areas11aand11band a distal instrument opening12. A fluid nozzle13with a nozzle spout is formed in the tip device3afor ejecting fluid to the viewing window portion10, such as air and washing water. The lighting window areas11aand11bare so disposed that the viewing window portion10is positioned between those. The lighting window areas11aand11bemit light from the lighting apparatus toward an object of interest in the gastrointestinal tract.

InFIG. 8, an imaging unit14is incorporated in the tip device3a. The imaging unit14includes a lens system with the viewing window portion10, and an image sensor, which is disposed behind the lens system and may be a CMOS or CCD image sensor as solid state imaging unit. Reflected light from the object of interest becomes incident upon the image sensor after passing the lens system with the viewing window portion10. A proximal instrument opening15is formed in the handle4. An instrument channel extends from the distal instrument opening12to the proximal instrument opening15. Various medical instruments are entered in the proximal instrument opening15for treatment or diagnosis, for example, a forceps, injection needle, high frequency surgical instrument, and the like.

The handle4includes steering wheels16and a fluid button17. The steering wheels16are rotatable for steering the steering device3bup and down and to the right and left. The fluid button17is depressed for supplying air or water or sucking body fluid. The universal cable9is connected to the handle4. The universal cable9contains a fluid tube18, a signal line19and a light guide device20. A proximal end of the fluid tube18is connected to the fluid supply source8. A distal end of the fluid tube18is connected to the fluid nozzle13, so that the fluid tube18supplies air or water from the fluid supply source8to the fluid nozzle13.

A proximal end of the signal line19is connected to the processing apparatus5. A distal end of the signal line19is connected to a CCD image sensor, for transmitting a control signal and an image signal. A distal end of the light guide device20is connected to the lighting window areas11aand11b. A proximal end of the light guide device20is connected to the light source apparatus6and transmits light from the light source apparatus6to the lighting window areas11aand11b. The processing apparatus5processes the image signal input from the signal line19in signal processing of suitable functions. A monitor display panel21is driven to display an image according to the image signal.

A propulsion assembly22is mounted on the tip device3aof the elongated tube3for moving the elongated tube3back and forth in the gastrointestinal tract. An actuating unit23actuates the propulsion assembly22.

The actuating unit23is electrically connected to the processing apparatus5. A protection sheath24of a flexible form extends from a proximal end of the propulsion assembly22, and includes two parallel sheath portions. An adhesive tape25or surgical tape attaches the protection sheath24to plural points on the elongated tube of the endoscope. The protection sheath24is prevented from moving irregularly in a body cavity upon entry or manipulation of the endoscope with the propulsion assembly22.

A first wire component26aor master wire component, and a second wire component26bor slave wire component (SeeFIG. 4) are entered through the protection sheath24, and have distal tips which are mechanically coupled to the propulsion assembly22. The first and second wire components26aand26bhave high flexibility and also high rigidity to torsion. Torque input for proximal tips of the first and second wire components26aand26bis transmitted by those without attenuation. A receptacle connector28is provided in the actuating unit23. A connection plug27of a fork shape couples proximal tips of the first and second wire components26aand26bto the receptacle connector28. A first motor29aor master motor and a second motor29bor slave motor (SeeFIG. 3) are incorporated in the actuating unit23. When the connection plug27is coupled to the receptacle connector28, the first wire component26abecomes rotatable by the first motor29a, and the second wire component26bbecomes rotatable by the second motor29b.

InFIG. 3, the actuating unit23includes a motor controller30and a CPU31. A rotational speed of the first motor29ais set at 2,000 rpm by the control with a current from the motor controller30. There is a foot switch32with which the motor controller30changes over the turn-on and turn-off states and forward and backward rotations of the first and second motors29aand29b.

The propulsion assembly22is utilized typically with the endoscope2for the large intestine for the purpose of assisting the advance and return typically in the sigmoid colon and the transverse colon. The propulsion assembly22includes an endless track device40(membrane) for contacting an inner wall of the gastrointestinal tract for exerting force for the advance and return to the elongated tube3of the endoscope2. The endless track device40has a shape with a cylindrical profile and with an outer surface of a toroid form, and is formed from a resiliently deformable sheet material. The endless track device40is movable endlessly in the axial direction AD.

InFIGS. 4-6, there is a barrel unit41or outer sleeve unit having inner and outer surfaces, along which the endless track device40extends and moves endlessly in an axial direction. InFIGS. 4 and 5, a developed form of the endless track device40is illustrated for structural simplicity. For a final form of the endless track device40, proximal and distal ends of a tubular material of the developed form are bent back externally, and are attached to one another by thermal welding. Thus, the endless track device40becomes shaped in a bag form as if a doughnut form were extended along its hole. Note that the endless track device40can be formed by molding by use of a mold set. Note that inFIGS. 4-7, a left end of the tip device3ais the distal end. A right end of the tip device3ais the proximal end directed to the handle4.

The endless track device40is formed from deformable material with flexibility, and compressibility and/or expandability. Examples of the material are polyvinyl chloride, polyamide resin, fluorocarbon resin, urethane, polyurethane, and other biocompatible plastic materials.

A drive unit42or inner sleeve unit is disposed in the endless track device40and the barrel unit41. The drive unit42includes a carrier sleeve43(inner support sleeve), a cap ring44, a distal cover flange45a, a proximal cover flange45b, a clamping device46, a C-ring47or coupling device, and a drive sleeve48. The carrier sleeve43has a cylindrical receiving hole, and an outer surface in a shape of a triangular prism. The cap ring44is triangular and attached to a proximal end of the carrier sleeve43with screws, press-fit, caulking or the like. The cover flanges45aand45bare fixed respectively to a distal end of the carrier sleeve43and a proximal end of the cap ring44. The clamping device46is helically engaged with an inner thread inside the carrier sleeve43, and moved axially upon being rotated. The C-ring47is formed from synthetic resin, and has a diameter increasing and decreasing upon movement of the clamping device46in the axial direction. The drive sleeve48is supported in the carrier sleeve43rotatably. SeeFIG. 6.

InFIG. 6, there are bearing rings50aand50bon which bearing balls49are supported in an annular form. The drive sleeve48is supported inside the carrier sleeve43with the bearing rings50aand50bin a rotatable manner, and is prevented from drop by the cap ring44fixedly engaged with a proximal end of the carrier sleeve43. Teeth of a worm gear51aand a spur gear51bare formed on an outer surface of the drive sleeve48. A pair of drive wheels52or worm wheels are supported on the carrier sleeve43in a rotatable manner, and are meshed with the worm gear51athrough an opening formed in the carrier sleeve43. The drive wheels52are arranged in three positions, and rotate about their gear shafts52ain an equal direction when the drive sleeve48rotates.

A distal end of the protection sheath24is attached to the inside of a recess formed on a proximal side of the cap ring44by use of adhesion or thermal welding. Ends of the first and second wire components26aand26bprotrude from the distal end of the protection sheath24, penetrate in through holes in the cap ring44, and extend distally of the cap ring44. A first pinion53aand a second pinion53bare fixedly secured to the first and second wire components26aand26b. As depicted in the drawing, shafts protrude from ends of the pinions53aand53bas rotational centers, and are entered through holes formed in the carrier sleeve43, so that the pinions53aand53bare respectively supported in a rotatable manner. Among the pinions53aand53b, the first pinion53aon the first wire component26ais meshed with the spur gear51bof the drive sleeve48. The second pinion53bon the second wire component26bis meshed with the first pinion53abut not with the spur gear51b. The drive sleeve48is driven by rotations of the first pinion53awith the first wire component26a. Each of the first and second wire components26aand26bis driven by rotational force discretely supplied by the actuating unit23. The second pinion53bis rotated in a direction reverse to that of the first pinion53a. Thus, rotational force of the second wire component26bis added to the rotational force of the first pinion53a, to rotate the drive sleeve48at a high torque.

Each of the cover flanges45aand45bhas a flange edge directed with a larger diameter, for contacting an inner surface of the endless track device40moved endlessly. The cover flanges45aand45bprevent dust, tissue of the body cavity and the like from entry in the propulsion assembly22together with movement of the endless track device40.

A distal end of the clamping device46has engagement teeth or the like arranged regularly in a circumferential direction. A tool is entered through the distal end and can be engaged with the engagement teeth of the clamping device46. The clamping device46, when rotated in a direction for helical engagement by the tool, is moved toward a proximal side axially. An inner tapered surface46aof the clamping device46ofFIG. 7presses the C-ring47and deforms the same to decrease its diameter. The tip device3aof the endoscope is entered in the receiving hole of the carrier sleeve43before the clamping device46is rotated for helical engagement. Then the inner surface of the C-ring47is pressed on the outer surface of the tip device3a, to which the carrier sleeve43can be fastened reliably.

The barrel unit41includes a distal end ring54a, a shield cover55, a support sleeve56and a proximal end ring54b. Elements of the barrel unit41are assembled to connect the drive unit42with the endless track device40according to the following steps.

InFIGS. 4 and 5, the drive unit42is positioned in the developed form of the endless track device40to cover the outer surface of the drive unit42with various elements. Then the drive unit42with the endless track device40is entered in a receiving hole of the support sleeve56. Three quadrilateral openings56aare formed in the support sleeve56and arranged at a pitch of 120 degrees circumferentially. Roller units57are fitted in respectively the quadrilateral openings56a.

Each of the roller units57includes a pair of holder frames58and three idler rollers59supported between the holder frames58. The holder frames58are formed from thin plates of metal with resiliency. End grooves for engagement are formed with ends of the quadrilateral openings56a. Ends of the holder frames58are engaged with the end grooves. A center portion of the holder frames58in the longitudinal direction is curved to enter a center space in the support sleeve56. The holder frames58are curved so that the idler rollers59on the holder frames58push the endless track device40to the drive wheels52. InFIGS. 9A and 9B, the endless track device40is tightly tensioned between the drive wheels52and the idler rollers59.

After the roller units57are fitted in the quadrilateral openings56a, the support sleeve56is not movable in the axial direction relative to the drive unit42, because the idler rollers59protrude internally from the inner surface of the support sleeve56. The idler rollers59are combined to tension the endless track device40. Also, the end rings54aand54bare attached to the support sleeve56. The shield cover55is fitted on the outer surface of the support sleeve56for tightly covering the support sleeve56and the roller units57.

A developed sheet of the endless track device40in a tubular shape is positioned between the drive unit42and the barrel unit41, which are combined together. Front and rear ends of the developed sheet are bent back externally to join the rear end to the front end. The front and rear ends can have inclined surfaces, according to which connected portions40aof the front and rear ends can be free from large irregularity in the thickness.FIG. 7is a section schematically illustrating the propulsion assembly22after being assembled. The endless track device40comes to have an inner space for containing the barrel unit41entirely. It is possible to charge the inner space with air, physiological saline water, synthetic resin of a colloid condition, lubricant such as oil or grease, or other suitable substances.

The endless track device40is formed by attachment of the ends of the tubular sheet, and is in a bag form ofFIG. 7. The endless track device40is tensioned between the drive wheels52and the idler rollers59. Rotations of the drive wheels52are transmitted to the endless track device40which can be moved in the axial direction.

A condition checking device60(end flange for visual aid) with a view segment (distal extension) is constituted by the distal end ring54awith the endless track device40. As will be described later, the condition checking device60is deformed resiliently when the propulsion assembly22is pushed on the inner wall of the body cavity, and enters the viewing area of the imaging unit14in a deformed state.

The distal end ring54aincludes a distal end wall61, a proximal end wall62and a neck portion63. The proximal end wall62has inner and outer diameters equal to those of the distal end wall61. The neck portion63is disposed between the end walls61and62. The distal end ring54ais a resilient device formed from silicon rubber, fluororubber, polyurethane and the like. The neck portion63includes a tapered wall63ahaving a diameter decreasing in a distal direction from the proximal side. In the embodiment, the condition checking device60extends so that its axis is aligned with the axial direction of the tip device3aupon mounting the propulsion assembly22thereon. The axis of the neck portion63is aligned with the optical axis of the imaging unit14.

When the propulsion assembly22with the tip device3ais entered in a body cavity and pushed on its inner wall, the neck portion63is resiliently deformed with the endless track device40(by way of the condition checking device60together with the distal end ring54a) in a direction transverse to the axial direction to enter the viewing area of the imaging unit14.

InFIG. 9A, the condition checking device60is not pushed on the inner wall of the body cavity. The condition checking device60is located outside a viewing area65of the imaging unit14. When the condition checking device60is pushed on the inner wall, the neck portion63is deformed radially to decrease its inner diameter. As described heretofore, the neck portion63is disposed coaxially with the imaging unit14. As illustrated inFIG. 9B, the condition checking device60enters the viewing area65at an equal width circumferentially when pushed on the inner wall.

The operation of the propulsion assembly22is described now. The propulsion assembly22is mounted on the tip device3aby positioning the condition checking device60distally of the tip device3a. A special device is used for mounting the propulsion assembly22, and rotates the clamping device46in a clockwise direction. As the clamping device46is helically engaged with the inner thread formed on the inner surface of the carrier sleeve43on the distal side, the clamping device46rotates in a clockwise direction and moves in the proximal direction. The inner tapered surface46apresses the C-ring47. The tapered surface is formed on the distal side of the C-ring47, and pushed by the inner tapered surface46aof the clamping device46to deform the C-ring47resiliently to decrease its diameter. Upon the deformation, the tip device3ais squeezed by the C-ring47to fasten the propulsion assembly22on the tip device3atightly.

The protection sheath24drawn from the proximal end of the propulsion assembly22is extended along the surface of the flexible device from the steering device. The plural indicia are present on the surface of the protection sheath24for indicating the positions for attachment of a tape at a suitable interval. The adhesive tape25is utilized to attach the protection sheath24on the steering device and flexible device of the endoscope at the indicia. The connection plug27at a proximal end of the protection sheath24is entered in the receptacle connector28and coupled to the actuating unit23. A power source for the actuating unit23is turned on.

When the imaging is ready as described above, the tip device3aof the endoscope2is entered in a body cavity, for example, large intestine. The foot switch32in connection with the actuating unit23is operated. The CPU31controls the motor controller30to supply the first and second motors29aand29bwith a current according to a rotational speed by use of the motor controller30. The first and second motors29aand29bare driven to rotate the first and second wire components26aand26b. In response, the pinions53aand53bare rotated. The drive sleeve48is rotated in cooperation with the spur gear51bmeshed with the first pinion53a. The second pinion53bis rotated in a direction reverse to that of the first pinion53a. Rotations of the second pinion53bare transmitted to the first pinion53a. Thus, the first and second motors29aand29bare utilized together in the actuating unit23to rotate the drive sleeve48.

When the worm gear51arotates together with the drive sleeve48, the drive wheels52are rotated in an equal direction respectively about the gear shafts52a. A return run66of the endless track device40is tensioned tightly between the tooth surface of the drive wheels52and the idler rollers59of the roller units57. Thus, the idler rollers59are rotated by rotations of the drive wheels52, to move the endless track device40in the axial direction of the drive sleeve48.

When the tip device3aof the endoscope2enters the large intestine with the propulsion assembly22and a working run68of the endless track device40contacts the inner wall, the propulsion force for moving the tip device3aforwards is obtained during the endless movement of the endless track device40. In other words, force exerted to the inner wall in the proximal direction is obtained.

Light from the light source apparatus6travels through the light guide device20and the lighting window areas11aand11band is applied to the inside of the large intestine. The imaging unit14in the tip device3aoutputs an image signal by imaging the inner wall of the large intestine. The image signal is transmitted by the signal line19in the endoscope2and input to the processing apparatus5, for the display panel21to display an image. A doctor or operator views the inner wall by use of the display panel21.

The operation of the propulsion assembly22for imaging a large intestine70is described now by referring toFIGS. 10A-16B. At first, the doctor or operator enters the tip device3awith the propulsion assembly22into a rectum71through the anus as illustrated inFIG. 10A. After the entry, the foot switch32is manipulated to move the endless track device40endlessly in a direction to advance the propulsion assembly22and the tip device3a. The propulsion assembly22and the tip device3areach a sigmoid colon72after the advance from the rectum71as illustrated inFIG. 10B.

The sigmoid colon72is a mobile part of the gastrointestinal tract with looseness, namely, is not attached to the body. When the propulsion assembly22and the tip device3aenter the sigmoid colon72, the doctor or operator endlessly moves the endless track device40in a direction of advance as much as 10-20 cm. SeeFIG. 11A. Then the elongated tube3is returned by pull from the body cavity inFIG. 11Bat an amount of the advance of the propulsion assembly22and the tip device3a. Thus, the sigmoid colon72with the looseness can be drawn toward the rectum71. Similarly, the step of advancing the propulsion assembly22and the tip device3aand the step of pulling the elongated tube3are repeated alternately, to straighten the sigmoid colon72. A lower end of a descending colon73becomes visible beyond the sigmoid colon72being straight. He or she sees the display panel21, and advances the propulsion assembly22and the tip device3ato pass the sigmoid colon72by viewing the lower end of the descending colon73in the viewing area.

InFIGS. 12A and 12B, a loop72aof the sigmoid colon72may occur typically when the sigmoid colon72has a great length and looseness. For entry into the sigmoid colon72, at first the propulsion assembly22and the tip device3aare moved forwards along the tortuous form of the sigmoid colon72as illustrated inFIG. 12A. The doctor or operator views the display panel21, and rotates the steering wheels16to steer the steering device3bin a direction of the tortuous form of the sigmoid colon72. SeeFIG. 12B.

The steering device3bis sufficiently steered according to the tortuous form of the sigmoid colon72. He or she returns the elongated tube3as long as 20-25 cm. The steering device3bis also returned to a straight form. See the state ofFIG. 13A. The loop72aof the sigmoid colon72is removed gradually for a straight form. He or she sees the display panel21and finds the straight form of the sigmoid colon72. Then it is possible to advance the propulsion assembly22and the tip device3ain the manner similar to the above. See the state ofFIG. 13B.

When the propulsion assembly22and the tip device3apass the sigmoid colon72and enter the descending colon73, a splenic flexure74comes to appear ahead of the tip device3aas illustrated inFIG. 14A. The doctor or operator views the splenic flexure74in the viewing area in the display panel21, and moves the propulsion assembly22and the tip device3adistally to pass the descending colon73.

When the propulsion assembly22and the tip device3areach the splenic flexure74beyond the descending colon73, the doctor or operator manipulates the steering wheels16by viewing the display panel21. The steering device3bis steered to seek for a direction of a transverse colon75beyond the splenic flexure74. Then the propulsion assembly22and the tip device3aare advanced. The steering device3bis steered according to a direction of the bend of the splenic flexure74. The propulsion assembly22and the tip device3aare advanced and can pass the splenic flexure74reliably. SeeFIG. 14B.

When the propulsion assembly22and the tip device3aare moved to pass the splenic flexure74and enter the transverse colon75, the operator rotates the steering wheels16to return the steering device3b. The transverse colon75is not attached to the body, but is mobile in a manner similar to the sigmoid colon72. Upon entry of the propulsion assembly22and the tip device3ain the transverse colon75, the operator repeats the advance of the propulsion assembly22and the tip device3a(SeeFIG. 15A) and the return of the elongated tube3(SeeFIG. 15B), to extend the transverse colon75straight in a manner similar to the sigmoid colon72. Then a hepatic flexure76appears ahead of the tip device3a.

When the propulsion assembly22and the tip device3areach the hepatic flexure76beyond the transverse colon75, the doctor or operator manipulates the steering wheels16by viewing the display panel21again. The steering device3bis steered to seek for a direction of an ascending colon77beyond the hepatic flexure76. Then the propulsion assembly22and the tip device3aare advanced. The steering device3bis steered according to a direction of the bend of the hepatic flexure76. The propulsion assembly22and the tip device3aare advanced and can pass the hepatic flexure76reliably. SeeFIG. 16A.

Upon the entry of the propulsion assembly22and the tip device3ain the ascending colon77beyond the hepatic flexure76, the steering wheels16are rotated to set the steering device3bin a straight form. After the reach to the ascending colon77, a cecum78becomes viewed. The propulsion assembly22and the tip device3aare advanced to reach the cecum78as illustrated inFIG. 16B.

As described heretofore, the sigmoid colon72and the transverse colon75are mobile (not attached) in the body, and failure is likely to occur in the smooth advance of the propulsion assembly22for the purpose of imaging of the large intestine70. It is likely that the propulsion assembly22is pushed on the inner wall of the large intestine70. As the propulsion assembly22has the condition checking device60, the endless track device40and the distal end ring54apushed on the large intestine70are deformed resiliently to enter the viewing area of the imaging unit14. The doctor or operator views the display panel21to observe entry of the condition checking device60in the viewing area, and can check the condition of the propulsion assembly22pushed on the large intestine70. In response to this, he or she stops the propulsion assembly22or returns the propulsion assembly22at a predetermined amount. Then the propulsion assembly22is advanced. Note that it is possible to stop the propulsion assembly22and then pull and return the elongated tube3at a predetermined amount. Note that the sleeve-shaped view segment of the condition checking device60is constituted by the return run66of the endless track device40and the distal end ring54a.

If a lesion is discovered during the imaging, the doctor or operator may enter a medical instrument suitable for the treatment through the proximal instrument opening15, to treat the lesion by protruding the instrument from the distal instrument opening12.

To unload the propulsion assembly22from the tip device3a, the clamping device46is rotated in a counterclockwise direction by use of a tool. The clamping device46moves axially upon rotation, and releases the C-ring47from pressure. The diameter of the C-ring47is increased by its resiliency to leave its inner surface from the tip device3a. Thus, the propulsion assembly22becomes easily removable from the endoscope.

In the above embodiment, the propulsion assembly22has the distal end ring54aand the endless track device40as a condition checking device. Other condition checking devices can be used in forms different from the above embodiment. A second preferred embodiment is described hereafter. Elements similar to those of the above embodiments are designated with identical reference numerals.

InFIG. 17, a propulsion assembly100for this purpose is illustrated, and includes an endless track device101(membrane), a barrel unit102or outer sleeve unit, and a drive unit103or inner sleeve unit. The barrel unit102supports the endless track device101. The drive unit103is disposed between the endless track device101and the barrel unit102. A distal end ring104is provided in the barrel unit102in place of the front end ring54aof the above embodiment. The distal end ring104is cylindrical and attached to the distal end of the support sleeve56. The endless track device101extends along inner and outer surfaces of the barrel unit102and endlessly moves in the axial direction in a manner similar to the endless track device40.

A condition checking device105(end flange for visual aid) with a view segment (distal extension) is disposed with the drive unit103in place of the distal cover flange45aof the above embodiment. The condition checking device105is disposed distally of the C-ring47, and includes a distal end wall106, a proximal end wall107and a neck portion108. The end walls106and107have an equal outer diameter and an equal inner diameter. The neck portion108is disposed between the end walls106and107. The condition checking device105is resilient, and formed from silicon rubber, fluororubber, polyurethane and the like. A distal end surface of the condition checking device105is disposed on a distal side from the endless track device101. The neck portion108has a tapered wall108ahaving a diameter decreasing at least from a proximal side toward a distal side. In the embodiment, the condition checking device105is positioned to align its axis with the axial direction of the tip device3aupon mounting the propulsion assembly100on the tip device3a. The axis of the neck portion108is aligned with the axis of the imaging unit14. Note that the sleeve-shaped view segment of the condition checking device105is constituted by the distal end wall106and the neck portion108.

The propulsion assembly100is mounted on the tip device3aby positioning the condition checking device105on a distal side from the tip device3a. When the condition checking device105is pushed on an inner wall of a body cavity, the neck portion108is deformed in the transverse direction resiliently to decrease the inner diameter, and enters a viewing area of the imaging unit14in a manner similar to the first embodiment. A doctor or operator can easily view the entry of the condition checking device105in the viewing area by observing the display panel21.

Also, it is possible inFIG. 17to form slits in the condition checking device105. SeeFIG. 20.

In the propulsion assembly22or100of the above embodiments, the condition checking device is deformable in the transverse direction. Another preferred embodiment is described now, in which an endless track device (membrane) constitutes a condition checking device.

InFIG. 18, a propulsion assembly110of the third embodiment includes an endless track device111(membrane), a barrel unit112or outer sleeve unit, and a drive unit113or inner sleeve unit. The endless track device111is used also as a condition checking device. The barrel unit112supports the endless track device111. The drive unit113is disposed inside the endless track device111and the barrel unit112. The barrel unit102is repeated for the barrel unit112. The drive unit42is repeated for the drive unit113.

The endless track device111is in a bag shape to extend along the inner and outer surfaces of the barrel unit112, and endlessly moves in the axial direction, in a manner similar to the endless track device40or101of the above embodiments. The endless track device111of the present example has an elongated form over the barrel unit112in the axial direction. The propulsion assembly110is fastened on the tip device3ain a state of protruding the endless track device111on the distal side from the tip device3a.

InFIG. 18, the endless track device111is not pushed on the inner wall of the body cavity. A loose portion111aof the endless track device111is created on a proximal side of the barrel unit112at a size of a difference in the axial range from the barrel unit112. The endless track device111is positioned on the proximal side with a sufficient inner space from the barrel unit112. The endless track device111covers a distal end of the barrel unit112tightly. Therefore, the endless track device111is disposed outside the viewing area of the imaging unit14when the endless track device111is not pushed on the inner wall.

InFIG. 19, the endless track device111is pushed on an inner wall115of a body cavity. A distal portion of the endless track device111does not move quickly due to friction of the inner wall115. The loose portion111aat the proximal end moves in the distal direction. A loose portion111bon an inner surface of the distal portion is created, and comes to enter the viewing area of the imaging unit14. Consequently, it is possible to view the portion of the endless track device111in the viewing area on the display panel21as a sleeve-shaped view segment.

In the above embodiments, the condition checking device is included in the propulsion assembly for the tip device3a. Another preferred condition checking device is a hood component for the tip device3aof the endoscope as described below.

InFIG. 20, an endoscope hood component120for the elongated tube3is mounted on the tip device3afor use. The hood component120includes a cylindrical support ring122and a tapered wall121. The support ring122is fitted on the outside of the tip device3ain a fixed manner.

The tapered wall121has a regular thickness, and is so tapered that its inner and outer diameters decrease gradually in the distal direction in contact with the support ring122. Plural slits123are formed in the tapered wall121to extend in the axial direction on the distal side. The slits123are arranged at a pitch of a regular angle in a circumferential direction of the tapered wall121. The tapered wall121is kept easily deformable by the slits123in directions transverse to the axial direction. The hood component120is fastened to the tip device3ain a state of extending the tapered wall121on a distal side of the tip device3a. Note that the sleeve-shaped view segment is constituted by the tapered wall121.

Note that the tapered wall121can have a gradually decreasing thickness in a distal direction from a proximal side, and can be formed in a structure resiliently deformable from the inside in the transverse directions with a small rigidity in the bend. Furthermore, the tapered wall121can have a gradually decreasing thickness in a proximal direction from a distal side, and can be so formed that a shift of the distal portion is enlarged toward the inside in the transverse direction by enlarging the bend in the proximal portion. Note that distribution of the thickness of the tapered wall121is not limited to those examples, but can be determined suitably for various purposes.

InFIG. 21A, the hood component120is not pushed on the inner wall of the body cavity. The tapered wall121is located outside a viewing area of the imaging unit14. When the hood component120is pushed on an inner wall124of a body cavity, the tapered wall121is deformed radially to decrease its inner diameter upon decrease of the width of the slits123. The tapered wall121enters the viewing area of the imaging unit14. The doctor or operator views the display panel21to observe entry of the tapered wall121in the viewing area in a manner similar to the first to third embodiments.

Also, it is possible to form the hood component120in a neck shape. In other words, a tapered wall in the hood component120can be present only in a portion disposed on a proximal side of the tip device3a.

In the above embodiments, the pushed condition is visually checked with the condition checking device upon entry of the elongated tube of the endoscope. However, the present invention is not limited to the above embodiments. It is possible to check the pushed condition at the time of the treatment of a lesion, as will be described with following variants of the embodiments.

This is specifically used for the time of invasive treatment to observe the pushed condition with the condition checking device, an example of the invasive treatment being the endoscope submucosal dissection (ESD) in which a mucosal lesion is found by imaging with the elongated tube3of the endoscope2, and is dissected.

The hood component120is attached to the tip device3aof the endoscope2for the purpose of the ESD procedure. InFIG. 22A, a doctor or operator creates indicia arranged around a mucosal lesion125which should be dissected. When the mucosal lesion125is discovered in the imaging, a high frequency surgical instrument126or high frequency scalpel is entered in the forceps channel in the endoscope2to protrude from the distal instrument opening12. The display panel21is viewed, while an electrode126ais set in contact with the surface of the mucosa, and supplied with a current of the high frequency. Portions of the mucosa on the electrode126aare ablated, so that a plurality of indicia127or marking are formed on the mucosa. Then the high frequency surgical instrument126is pulled out of the forceps channel. A local injection apparatus (not shown) is punctured in the forceps channel instead of the high frequency surgical instrument126. An injection needle is used to inject a fluid of a drug. As a result, the mucosal lesion125becomes swelled and protruded as illustrated inFIG. 22B. When the mucosal lesion125is enlarged sufficiently, the local injection apparatus is pulled out of the forceps channel. Then the high frequency surgical instrument126is penetrated again. InFIG. 22C, a current of high frequency is supplied to the electrode126aof the high frequency surgical instrument126. When the elongated tube3of the endoscope2is moved or the steering wheels16are rotated by manipulation, the electrode126aof the high frequency surgical instrument126is moved along the indicia127to incise and peel the mucosal lesion.

It is possible in the course of the ESD to press the tip device3aon a portion between a fascia128under the mucosal lesion125and the mucosal lesion125.FIG. 22Dillustrates this state for peeling the mucosal lesion125by advancing the elongated tube3of the endoscope2. Bleeding may occur from the tissue after dissecting the mucosal lesion125. The tip device3aand the hood component120must be pushed slowly at a suitable pressure. When the hood component120is pushed on the inner wall as described above, the tapered wall121is resiliently deformed radially to decrease its inner diameter. He or she can view the display panel21to see the entry of the tapered wall121in the viewing area. When the hood component120enters the viewing area, he or she reduces force for thrusting the elongated tube3, as the pushed condition of the tip device3aand the hood component120can be monitored. Thus, the mucosal lesion125can be peeled by pushing the tip device3aand the hood component120on the portion between the mucosal lesion125and the fascia128under the mucosal lesion125with suitable force.

Note that the inclination of the tapered wall of the above embodiments can be preferably determined so as to facilitate deformation of the condition checking device60,105or120, and facilitate local entry of the condition checking device60,105or120in the viewing area65of the viewing window portion10.

In the above embodiments, the endoscope is for a medical use. However, an endoscope of the invention can be one for industrial use, a probe of an endoscope, or the like for various purposes.