Patent Publication Number: US-2012029282-A1

Title: Guide assembly for endoscope

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a guide assembly for an endoscope. More particularly, the present invention relates to a guide assembly capable of causing an endoscope to enter a body cavity smoothly, and keeping a steering device in the endoscope steerable readily even with a self-propelled structure for guiding. 
     2. Description Related to the Prior Art 
     An endoscope is used to diagnose a body cavity, such as a large intestine in a gastrointestinal tract. Manipulation of the endoscope is a difficult process, because the large intestine is a tortuous organ in a human body, and some body parts are very changeable in the position in the body, such as a sigmoid colon and a transverse colon. Learning the manipulation of the endoscope of the large intestine requires much experience and time. If a doctor is insufficiently skilled in the manipulation, physical load to the body of a patient will be very large. 
     U.S. Pat. Nos. 6,971,990 and 7,736,300 (corresponding to JP-A 2009-513250) disclose a self-propelled apparatus for propelling the endoscope in the axial direction in the body cavity to facilitate the manipulation even for an unskilled operator or doctor. The self-propelled apparatus of the documents includes a movable endless track device or crawler device or toroidal device. The endless track device is driven to turn around for the endoscope to travel mechanically. Force of propulsion is created by the endless track device contacting a wall of the large intestine, so as to guide the endoscope deeply in the body cavity. 
     However, U.S. Pat. Nos. 6,971,990 and 7,736,300 disclose the self-propelled apparatus in which a support or housing of the endless track device longitudinally extends in the axial direction of the elongated tube. There is a problem in that the steering of the steering device is obstructed by the combined use of the guide assembly or the self-propelled apparatus, and that flexibility of the elongated tube may be lower. Accordingly, the manipulation may be more difficult. 
     SUMMARY OF THE INVENTION 
     In view of the foregoing problems, an object of the present invention is to provide a guide assembly capable of causing an endoscope to enter a body cavity smoothly, and keeping a steering device in the endoscope steerable readily even with a self-propelled structure for guiding. 
     In order to achieve the above and other objects and advantages of this invention, a guide assembly of a self-propelled type for an endoscope having a section of an elongated tube for entry in a body cavity is provided, the elongated tube having a steering device on a distal side with a variable direction. At least first and second self-propelled units are mounted about the steering device, arranged with one another, for propulsion in an axial direction of the elongated tube by contacting a wall of the body cavity, the second self-propelled unit receiving force for driving from an external drive source. A flexible connector connects the second self-propelled unit to the first self-propelled unit, and transmitting the force applied to the second self-propelled unit to the first self-propelled unit. 
     The connector includes at least two coils having diameters different from one another, and combined by containing a first one in a second one thereof so that winding directions thereof are opposite to one another. 
     The force is torque in a rotational direction about an axis of the axial direction. Each of the at least first and second self-propelled units includes a first sleeve, secured around the steering device, and rotated thereabout by the torque. A driving device is connected with the first sleeve, for converting the torque into force in the axial direction. 
     Each of the at least first and second self-propelled units includes an endless track device, having an annular surface, driven by the driving device when the torque is applied to the first sleeve, for turning around on an endless track in the axial direction. 
     The first sleeve is constituted by a worm gear. Furthermore, a bearing sleeve is mounted around the steering device, for supporting the worm gear in a rotatable manner about the axis. The driving device includes an engagement roller, having teeth, rotatable about an axis crosswise to the axial direction, meshed with the worm gear, for moving the endless track device. 
     The driving device further comprises a first ring sleeve disposed about the worm gear. A first through opening is formed through a wall of the first ring sleeve, for supporting the engagement roller in a rotatable manner. A second ring sleeve is disposed about the first ring sleeve, for supporting the endless track device movably. A second through opening is formed through a wall of the second ring sleeve. An idler roller is secured in the second through opening, for rotating about an axis crosswise to the axial direction, and nipping the endless track device in cooperation with the engagement roller. 
     The idler roller is constituted by a pair of idler rollers, and the engagement roller is disposed between the idler rollers. 
     Furthermore, a flexible tubular cover covers the at least two coils. 
     The endless track device is formed from fluid-impermeable material, and internally charged with liquid. 
     In a preferred embodiment, the endless track device is formed from fluid-impermeable material, and internally charged with gel. 
     The endless track device is formed from biocompatible plastic material. 
     Preferably, the second self-propelled unit is controlled remotely. 
     Preferably, the at least two coils are three coils. 
     Preferably, the connector is single. 
     Consequently, it is possible to keep a steering device in the endoscope steerable readily even with a self-propelled structure for guiding, because the flexible connector connects the second self-propelled unit to the first self-propelled unit suitably. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above objects and advantages of the present invention will become more apparent from the following detailed description when read in connection with the accompanying drawings, in which: 
         FIG. 1  is a plan illustrating an endoscope system; 
         FIG. 2  is a perspective view illustrating a guide assembly; 
         FIG. 3  is an exploded perspective view illustrating the guide assembly; 
         FIG. 4  is a vertical section illustrating the guide assembly. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) OF THE PRESENT INVENTION 
     In  FIG. 1 , an endoscope system  2  includes an endoscope  10  and a self-propelled type of guide assembly  11 . The endoscope  10  has a handle device  12  and an elongated tube  13  or guide tube disposed to extend from the handle device  12  for entry in a body cavity, for example, a large intestine of a gastrointestinal tract. A universal cable  14  is disposed to extend from the handle device  12 . Connection plugs (not shown) are disposed at a proximal end of the universal cable  14  for connection with a light source apparatus and a processing apparatus (not shown) in a removal manner. 
     The handle device  12  includes steering wheels  15 , an air/water button  16  and a suction button  17 . The air/water button  16  is operable for supplying air or water through a distal end of the elongated tube  13 . An instrument channel  18  is formed through the handle device  12  and the elongated tube  13  for receiving entry of a forceps, electrocautery device or other medical instrument. 
     The elongated tube  13  includes a flexible device  19 , a steering device  20  and a head assembly  21  in a sequence in a distal direction from the handle device  12 . The flexible device  19  has a length as great as several meters for reach of the head assembly  21  to an object of interest in a body cavity. The steering device  20  bends up and down and to the right and left in response to operation of the steering wheels  15  of the handle device  12 . Thus, the head assembly  21  can be steered in a desired direction in the patient&#39;s body. 
     An imaging window  30  is formed in the head assembly  21  for imaging of a body part in the body. See  FIG. 2 . The head assembly  21  contains objective optics and an image sensor or solid-state image pickup device for imaging, such as CCD and CMOS image sensors. The image pickup device is connected to the processing apparatus by a signal line, which extends through the elongated tube  13 , the handle device  12  and the universal cable  14 . An object image of the body part is focused on a reception surface of the image pickup device, and is converted into an image signal. The processing apparatus processes the image signal from the image pickup device through the signal line by image processing, and obtains a video signal by conversion after the image processing. The object image is output and displayed on a monitor display panel (not shown) according to the video signal. 
     Various openings are formed in the head assembly  21  as illustrated in  FIG. 2 . Among those, a lighting window  31  passes illumination light from a light source apparatus toward an object of interest. An air/water nozzle  32  supplies air or water toward the imaging window from an air/water supply device in the light source apparatus in response to depression of the air/water button  16 . An instrument opening  33  causes a distal end of a medical instrument from the instrument channel  18  to appear distally. 
     The guide assembly  11  is a device mounted on the endoscope  10 , for assisting forward and backward movement of the elongated tube  13  of the endoscope  10  in a body cavity. A drive source  22  or motor drives the guide assembly  11 . A torque coil structure  49  of a multi component type or three component type is connected with the drive source  22 , and transmits torque to the guide assembly  11 . See  FIG. 3 . There is a protection sheath  23  through which the torque coil structure  49  is entered at its full length. The torque coil structure  49  rotates in the protection sheath  23  when the drive source  22  is actuated. 
     An overtube  24  is used to cover the elongated tube  13 , and is ready to expand and shrink in an axial direction of an axis A of the elongated tube  13 . The protection sheath  23  of the torque coil structure  49  is entered between the overtube  24  and the elongated tube  13 . 
     A controller (not shown) controls the drive source  22 . A button panel (not shown) is connected to the controller. The button panel includes a command button for inputting command signals for forward movement, backward movement and stop of the self-propelled type of guide assembly  11 , and a speed button for changing a moving speed of the guide assembly  11 . Note that a control program can be prepared suitably for an object to be imaged. The drive source  22  can be actuated according to the control program without manipulating the button panel, so as to actuate the guide assembly  11  automatically. 
     In  FIG. 2 , the guide assembly  11  includes a first self-propelled unit  11   a  and a second self-propelled unit  11   b  or guide structures. The first self-propelled unit  11   a  is positioned on a distal side from the second self-propelled unit  11   b . Those are secured to the steering device  20  of the elongated tube  13  of the endoscope  10 . Each of the self-propelled units  11   a  and  11   b  includes a movable endless track device  34  or crawler device or toroidal device, and a driving device  35  or support device or barrel device with a rotating mechanism. The endless track device  34  has a hollow shape with an annular surface, is movable on an endless track, and is formed from a biocompatible plastic material having flexibility and fluid-impermeability. An example of the biocompatible plastic material is polyvinyl chloride. Also, polyamide resin, fluorocarbon resin, polyurethane resin and the like can be used. The inside of the endless track device  34  is filled with suitable fluid, such as liquid, gel, gas, or a combination of at least two of liquid, gel and gas. 
     The endless track device  34  of each of the self-propelled units  11   a  and  11   b  endlessly turns around in the axial direction of the axis A. The endless track device  34  of the first self-propelled unit  11   a  is turned in synchronism with turn around of the endless track device  34  of the second self-propelled unit  11   b . When an outer surface  34   a  of the endless track device  34  contacts an inner wall of a body cavity, propelling force occurs in the self-propelled units  11   a  and  11   b  to move the elongated tube  13  along the axis A. 
     To propel the elongated tube  13  in the distal direction, the elongated tube  13  is moved by the turn around of the endless track device  34  in an endless manner to orient the outer surface  34   a  in the proximal direction. To move the elongated tube  13  in the proximal direction, the endless track device  34  is turned around endlessly to orient the outer surface  34   a  in the distal direction. 
     In  FIGS. 3 and 4 , the driving device  35  includes a first ring sleeve  40  and a second ring sleeve  41 . Both of the first and second ring sleeves  40  and  41  are cylindrical, and have an equal size along the axis A. A diameter of the first ring sleeve  40  is smaller than that of the second ring sleeve  41 . The first ring sleeve  40  is contained in and surrounded by the second ring sleeve  41 . In  FIG. 3 , the endless track device  34  is not depicted. 
     Through openings  40   a  are formed in a wall of the first ring sleeve  40 . An engagement roller  42  or drive roller or toothed roller has teeth, is disposed inside each of the through openings  40   a , and rotates about an axis perpendicular to the axis A. The engagement roller  42  is disposed at the middle of the first ring sleeve  40  in the direction of the axis A. Three engagement rollers  42  are arranged at a pitch of 120 degrees in the circumferential direction of the first ring sleeve  40 . 
     Through openings  41   a  are formed in a wall of the second ring sleeve  41 . A pair of idler rollers  43  or driven rollers are disposed inside respectively the through openings  41   a . Each of the idler rollers  43  is rotatable about an axis parallel to the axis of the engagement roller  42 . Three pairs of idler rollers  43  are arranged at a pitch of 120 degrees in the circumferential direction of the second ring sleeve  41 . When the first ring sleeve  40  is contained in the second ring sleeve  41 , the second ring sleeve  41  is positioned relative to the first ring sleeve  40  to set the engagement roller  42  between the idler rollers  43 . The endless track device  34  is mounted about the second ring sleeve  41  by passage in its end openings. The endless track device  34  is squeezed between the engagement roller  42  and the idler rollers  43 . An inner surface  34   b  of the endless track device  34  is contacted by the idler rollers  43 , which are rotated by endless turn around of the endless track device  34 . 
     Specifically, the endless track device  34  is prepared in the following manner. At first, a plastic tube having two open ends with flexibility and elasticity is initially formed from a sheet or film of the above-described suitable material. The plastic tube is halfway inserted in a sleeve lumen of the second ring sleeve  41 . Then a portion of the plastic tube outside the sleeve lumen is bent back externally and extended to cover the periphery of the second ring sleeve  41 . A first side line of the inserted half of the plastic tube is opposed to a second side line of the bent half to the plastic tube, so that the halves are attached together along the first and second side lines by adhesion, welding or other suitable method. Finally, the toroidal shape of the endless track device  34  is obtained. 
     A worm gear  44  or worm thread is contained in the first ring sleeve  40 . There is a bearing sleeve  45  or holding sleeve for supporting a worm gear sleeve  44   s  (worm drive or worm sleeve as a first sleeve) including the worm gear  44 . The elongated tube  13  of the endoscope  10  is entered in the bearing sleeve  45  which becomes mounted fixedly on the elongated tube  13 . As the bearing sleeve  45  is positioned on the elongated tube  13 , the head assembly  21  projects distally from the bearing sleeve  45  of the first self-propelled unit  11   a . A worm thread of the worm gear  44  rotates about the bearing sleeve  45  in bearing contact along the axis A. The worm gear  44  is meshed with the engagement roller  42 , which is rotated by the worm gear  44 . 
     A rear end ring  46  is attached to the first ring sleeve  40  of the second self-propelled unit  11   b . A flange  46   a  is a portion of the rear end ring  46  at its peripheral edge. The flange  46   a , when the rear end ring  46  is attached to the first ring sleeve  40 , contacts a rear edge of the first ring sleeve  40 . An end of the bearing sleeve  45  is fitted in an inner hole of the rear end ring  46  in a tight manner without dropping. 
     Spur gear teeth  47  or a driven gear is formed with a proximal end of the worm gear  44  inside the first ring sleeve  40  of the second self-propelled unit  11   b , the teeth being arranged about the axis A. A pinion  48  is secured to the rear end ring  46  in a rotatable manner. An axis of the pinion  48  is parallel to the axis A. The pinion  48  is meshed with the spur gear teeth  47 , and is firmly connected with the torque coil structure  49 . Thus, the pinion  48  is rotated by rotation of the torque coil structure  49 . The torque coil structure  49  includes three coil springs combined in a multi layer form in such a state that their winding directions are different from one another. The torque coil structure  49  can transmit torque even upon rotating in any of the forward and backward directions. When the pinion  48  rotates, the spur gear teeth  47  rotate responsively. 
     A front end ring  50  is attached to the first ring sleeve  40  of the first self-propelled unit  11   a . A flange  50   a  is a portion of the front end ring  50  at its peripheral edge. The flange  50   a , when the front end ring  50  is attached to the first ring sleeve  40 , contacts a front edge of the first ring sleeve  40 . An end of the bearing sleeve  45  is fitted in an inner hole of the front end ring  50  in a tight manner without dropping. 
     A proximal end of the worm gear  44  in the first self-propelled unit  11   a  has an outer annular recess. A distal end of the worm gear  44  in the second self-propelled unit  11   b  has an outer annular recess. A connecting ring  51  is fitted in each outer annular recess of the worm gear  44  on a suitable side. There is a connecting coil structure  52  of a multi component type or three component type. Each of ends of the connecting coil structure  52  is fitted on the connecting ring  51 . The connecting ring  51  and the connecting coil structure  52  rotate together with the worm gear  44 . Thus, torque of the worm gear  44  in the second self-propelled unit  11   b  is transmitted to the worm gear  44  of the first self-propelled unit  11   a.    
     The connecting coil structure  52  includes a first coil spring  52   a , a second coil spring  52   b  and a third coil spring  52   c . The first coil spring  52   a  is positioned externally. The second coil spring  52   b  has an outer diameter substantially equal to an inner diameter of the first coil spring  52   a . The third coil spring  52   c  has an outer diameter substantially equal to an inner diameter of the second coil spring  52   b . The coil springs  52   a ,  52   b  and  52   c  are combined in a multi layer form in such a state that their winding directions are different from one another. Specifically, the first and third coil springs  52   a  and  52   c  have turns wound in the counterclockwise direction. The second coil spring  52   b  has turns wound in the clockwise direction. 
     When the connecting coil structure  52  is rotated in the counterclockwise direction by rotation of the connecting ring  51 , the first and third coil springs  52   a  and  52   c  are shifted and tightened in an inward direction, the second coil spring  52   b  being shifted and loosened in an outward direction. Thus, torque can be transmitted with high efficiency owing to the tight contact between the first and second coil springs  52   a  and  52   b . When the connecting coil structure  52  is rotated in the clockwise direction by rotation of the connecting ring  51 , the first and third coil springs  52   a  and  52   c  are shifted and loosened in the outward direction, the second coil spring  52   b  being shifted and tightened in the inward direction. Thus, torque can be transmitted with high efficiency owing to the tight contact between the second and third coil springs  52   b  and  52   c . Note that a structure and operation of the torque coil structure  49  are basically the same as the connecting coil structure  52 . 
     A tubular cover  53  is flexible along the axis A of the elongated tube  13 , and has one end to which the connecting ring  51  is secured. The tubular cover  53  covers the connecting coil structure  52 , and prevents body fluid from contacting the connecting coil structure  52 . In  FIG. 3 , the tubular cover  53  is not depicted. 
     The operation of the endoscope system  2  is described now. At first, the overtube  24  is retained on the elongated tube  13  of the endoscope  10 . The elongated tube  13  is entered in the bearing sleeve  45  to mount the guide assembly  11  on the elongated tube  13 . 
     After securing the overtube  24  and the guide assembly  11  to the endoscope  10 , a power source of the processing apparatus, light source apparatus and controller is turned on. Then personal information of the patient is input. The elongated tube  13  of the endoscope  10  is entered in his of her body cavity. 
     After the head assembly  21  is advanced to a predetermined body part, for example, slightly short of a sigmoid colon, then the button panel is operated to turn on a power source for the drive source  22  of the self-propelled type of guide assembly  11 . Then a command signal for start is input with the button panel. The drive source  22  rotates the torque coil structure  49  in a predetermined direction. In the second self-propelled unit  11   b , the pinion  48  is rotated by rotation of the torque coil structure  49 . The worm gear  44  is rotated by the pinion  48 . Thus, the connecting coil structure  52  rotates together with the worm gear  44  in the second self-propelled unit  11   b , to shift the worm gear  44  of the first self-propelled unit  11   a  inwards for firm contact. Accordingly, transmission of torque to the worm gear  44  of the first self-propelled unit  11   a  can be efficient, because the torque of the worm gear  44  of the second self-propelled unit  11   b  is transmitted by the connecting coil structure  52 . 
     When the worm gear  44  rotates together with the self-propelled units  11   a  and  11   b , the engagement roller  42  is rotated responsively. Thus, the endless track device  34  endlessly turns around in each of the self-propelled units  11   a  and  11   b . The guide assembly  11  advances in the axis direction of the elongated tube  13  when the outer surface  34   a  of the endless track device  34  contacts a wall of a body cavity. Consequently, the head assembly  21  advances along the wall of the body cavity. 
     When a command signal for a change is input by operating the button panel, the drive source  22  changes a rotational speed of the torque coil structure  49 . Thus, a moving speed of the self-propelled type of guide assembly  11  is changed. When a command signal for return is input by operating the button panel, the drive source  22  causes the torque coil structure  49  to rotate in a backward direction, to move the guide assembly  11  and the head assembly  21  backwards. When a command signal for a stop is input by operating the button panel, the drive source  22  stops to stop moving the guide assembly  11 . It is possible to propel the head assembly  21  through the body cavity to an object of interest by suitably repeating those steps of the movement. 
     A doctor or operator steers the steering device  20  of the endoscope  10  by manipulating the steering wheels  15 , to bend the head assembly  21  in a desired direction. As the second self-propelled unit  11   b  is connected to the first self-propelled unit  11   a  by the connecting coil structure  52  in the guide assembly  11 , the connecting coil structure  52  bends together with the steering device  20  according to the flexibility, for the self-propelled units  11   a  and  11   b  to follow the steering of the steering device  20 . This is effective in keeping the steering device  20  free from being obstructed by the guide assembly  11 . 
     In the embodiment, the connecting coil structure  52  is used between the two worm gears  44  in the self-propelled units  11   a  and  11   b . However, other elements may be used for transmitting torque of the second self-propelled unit  11   b  to the first self-propelled unit  11   a  and having flexibility along the axis A, for example, only one coil spring, a rubber tube or the like. 
     Although the self-propelled units  11   a  and  11   b  are disclosed the above embodiment, the number of the self-propelled units or guide structures may be three or more. Also, the number of the drive sources or motors for the self-propelled units may be two or more. 
     In the above embodiments, the self-propelled type of guide assembly is used with the endoscope for a medical use. Also, the guide assembly of the invention can be used with an endoscope for industrial use, an ultrasonic probe, or other instruments for imaging in a cavity. Although the movable endless track device or crawler device or toroidal device is turned around in the guide assembly, a guide assembly of the invention can be any mechanical type for entry in a body cavity as a component for an instrument for imaging. 
     Although the present invention has been fully described by way of the preferred embodiments thereof with reference to the accompanying drawings, various changes and modifications will be apparent to those having skill in this field. Therefore, unless otherwise these changes and modifications depart from the scope of the present invention, they should be construed as included therein.