Abstract:
The present invention is a telescopic drive device of a device for holding a surgical instrument. The telescopic drive device includes a support; a first telescopic stage carried by the support; a first telescopic stage carried by the support, the first telescopic stage being able to perform a first motion with respect to the support; a second telescopic stage, which is able to perform a second motion with respect to the first telescopic stage; and a drive system, which is operable to drive the first and second motions. The first telescopic element performs the first motion and the second telescopic element simultaneously performs the second motion. The telescopic drive is operable to support a further device and to move the further device such that the movement is centered around a point or wherein each of the telescopic elements is arcuate.

Description:
CROSS-REFERENCE TO RELATED U.S. APPLICATIONS 
     Not applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     NAMES OF PARTIES TO A JOINT RESEARCH AGREEMENT 
     Not applicable. 
     REFERENCE TO AN APPENDIX SUBMITTED ON COMPACT DISC 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a telescopic support, and in particular concerns a telescopic support for holding and/or manipulating a medical device. 
     2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98. 
     There are several applications in which a drive is used to maneuver a carrier around a fixed point. An example of such an application is a robotic arrangement to hold a camera for use in endoscopy, where the endoscope is inserted into an incision in the body of a patient, and is then driven to move along or around two or more axes in such a way that the movement is confocal around the incision. This means that the endoscope may be moved with the point of the incision being the center of motion, so that the endoscope remains inserted into the incision and does not exert any substantial forces on the sides of the incision. 
     Confocal motion of this type often comprises pan, tilt, and zoom motions. During the “tilt” movement, the angle of the endoscope changes with respect to the surface of the patient&#39;s skin in which the incision is made. 
     In order to achieve tilt motion without exerting forces on the sides of the incision in the patient&#39;s body, an arcuate arm may be provided, having a radius of curvature which is centered on the incision. The endoscope is typically carried at one end of the arcuate arm, and it will be appreciated that driving the arcuate arm to describe a rotary motion about the incision, with all parts of the arm remaining at the same distance from the incision, causes the endoscope to tilt with respect to the patient, whilst remaining substantially motionless at the point where the endoscope passes through the incision. 
     Depending upon the application for which the endoscope is being used, however, the range of tilt motion that is required of the endoscope may be relatively large. To accommodate the positions of the endoscope that are required in various surgical operations, an endoscope may be required to be positioned in a substantially vertical orientation (i.e. perpendicular to the skin of the patient in which the incision is made), to a position which is a few degrees below horizontal (i.e. below the plane of the patient&#39;s skin in which the incision is made). In total, it is desirable for the endoscope to have a range of motion of around 110°. 
     If a solid arcuate arm is used however, it will be understood that this arcuate arm must cover at least 110° of arc in order to be able to support the endoscope in both of these end-of-range positions. This raises difficulties since, if the endoscope is moved to a substantially vertical position, the far end of the arcuate arm (i.e. the end furthest from the point at which the endoscope is supported) would travel sufficiently far along its arcuate path to press into the skin of the patient. Clearly, this is undesirable. 
     It is an object of the present invention to seek to ameliorate this difficulty. 
     BRIEF SUMMARY OF THE INVENTION 
     Accordingly, one aspect of the present invention provides a device for holding a surgical instrument, the device having a telescopic drive comprising a support; a first telescopic stage carried by the support, the first telescopic stage being able to perform a first motion with respect to the support; a second telescopic stage, which is able to perform a second motion with respect to the first telescopic stage; and a drive system, which is operable to drive the first and second motions, so that the first telescopic element performs the first motion and the second telescopic element simultaneously performs the second motion, wherein each of the telescopic elements is arcuate. 
     Preferably, each of the telescopic elements has a range of motion with respective ends, and wherein, starting from a position in which both telescopic elements are at one end of their respective ranges of motion, the drive system is operable to drive the telescopic elements simultaneously so that the telescopic elements reach the ends of their respective ranges of motion substantially simultaneously. 
     Preferably a third telescopic stage is provided, the third telescopic stage being adapted to perform third motion with respect to the second telescopic stage, and wherein the drive arrangement is configured to drive the third motion simultaneously with the first and second motions. 
     Conveniently, the endoscope is supported by the telescopic drive. 
     Preferably, the telescopic drive is operable to support a further device and to move the further device such that the movement is centered around a point. 
     Advantageously, the telescopic drive moves the further device in a tilt movement with respect to the point. 
     Conveniently, the further object may be moved along or around a plurality of axes to describe motion that is confocal about the point. 
     Advantageously, the device is a robot. 
     Accordingly, one aspect of the present invention provides a device for holding a surgical instrument, the device having a telescopic drive comprising a support; a first telescopic stage carried by the support, the first telescopic stage being able to perform a first motion with respect to the support; a second telescopic stage, which is able to perform a second motion with respect to the first telescopic stage; and a drive system, which is operable to drive the first and second motions, so that the first telescopic element performs the first motion and the second telescopic element simultaneously performs the second motion, wherein the telescopic drive is operable to support a further device and to move the further device such that the movement is centered around a point. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       In order that the present invention may be more readily understood, embodiments thereof will now be described, by way of example, with reference to the accompanying drawings. 
         FIG. 1  shows a perspective view of the telescopic drive embodying the present invention. 
         FIG. 2  shows a schematic view of a gearing arrangement for use with the present invention. 
         FIG. 3  shows a schematic view of an alternate gearing arrangement for use with the present invention. 
         FIG. 4  shows a perspective view of a telescopic drive embodying the present invention having an additional third telescoping stage. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to  FIG. 1 , a part of a surgical robot is shown, supporting an endoscope  1 . The endoscope  1  comprises an elongate body  2 , from which a thin, elongate camera  3  protrudes. Images are collected at the far end of this camera  3 , and the camera  3  may also include a light source to illuminate objects within the field of vision of the camera. It will be understood that it is this camera  3  which is inserted into an incision  50  in the patient&#39;s body during endoscopic surgery, to allow the surgeon to inspect a part of the patient&#39;s body, or to see the progress of a surgical procedure. The camera  3  may be extended from, or retracted into the housing  2 , thus allowing the “zoom” motion of the endoscope  1  along axis  46 . It will be understood that this zoom motion does not place any significant stress on the sides of the incision  50 . 
     Images collected by the camera  3  are transmitted from the endoscope  1  to a remote location, where, for example, they may be viewed by a surgeon on a screen during surgery. This transmission may take place wirelessly, or by any other suitable means. 
     The endoscope  1  is supported by an outer arm  4 , which takes the form of a sturdy, planar strip whose shape describes a section of arc having a constant radius of curvature with respect to axis  44 . As will be understood from the above, the radius of curvature of the outer arm  4  is centered on a point along the length of the camera  3 . It is this point along the length of the camera  3  that will pass through the incision  50  in a patient&#39;s body during endoscopic surgery, and hence that will be the focus of motion of the endoscope  1 . 
     The outer arm  4  is, itself, carried by an inner arm  5 . The inner arm  5  takes the form of an arcuate sleeve, having the same radius of curvature as the outer arm  4 . The inner arm  5  defines an internal passage  6 , which is shaped and sized to receive the outer arm  4  slidably. The outer arm  4  may be received telescopically within the sleeve of the inner arm  5 , so that when the outer arm  4  is fully retracted into the inner arm  5  the endoscope  1  abuts or lies close to the inner arm  5 . The outer arm  4  may, however, be extended from the inner arm  5 , so that the endoscope  1  is supported at some distance from the inner arm  5 . 
     The inner arm  5  is supported by a housing  7 , which is sufficiently large that the inner arm  5  may be fully or substantially fully retracted into the housing  7 . 
     It will be appreciated that, if the inner arm  5  is fully retracted into the housing  7 , and the outer arm  4  is fully retracted into the inner arm  5 , the endoscope  1  will abut or lie close to the housing  7 . In this position, the elongate camera  3  of the endoscope  1  is at or near one end of its range of movement. The inner arm  5  may be extended from the housing  7 , and the outer arm  4  may be extended from the inner arm  5 , and in this position the endoscope  1  is at or near the other end of its range of motion. 
     The housing  7  is supported by a support  8 , which allows the housing  7  to be rotated about an axis  40  that passes from a point of support  42  through the incision  50  in the patient&#39;s body. This rotation allows the “pan” motion of the endoscope  1  to occur. The support  8  is preferably part of a larger surgical robot (not shown) that supports the endoscope  1  in an appropriate position for a surgical procedure. 
     It will be appreciated that the provision of a two-stage telescopic arcuate arm  4 ,  5  can alleviate the problem discussed above. If the inner and outer arms  5 ,  4  were replaced by one solid arcuate arm, then when the endoscope  1  was at one end of its range of motion in which it was closest to the housing  7 , the arcuate arm would protrude from a back end of the housing  7  and would press into the body of the patient. The fact that the outer arm  4  may fit inside the inner arm  5  prevents this from occurring. 
     In conventional telescopic arrangements of this type, however, one telescopic element is fully extended during a first phase of extension, and motion of this telescopic element then stops while motion of a further telescopic element commences. For instance, in a conventional arrangement of this type, starting from a situation in which both arms  4 ,  5  were retracted and received within the housing  7 , a first step might be to extend the outer arm  4  fully, without extending the inner arm  5 . Only once the outer arm  4  had reached the full end of its range of motion, the inner arm  5  would be extended, without further relative motion of the outer arm  4  with respect to the inner arm  5 . 
     For an application such as endoscopic surgery, however, motion of this type is likely to cause problems. At the point where motion of the outer arm  4  ends, and motion of the inner arm  5  commences, there will inevitably be some “jerkiness” or driving the motion discontinuity in the motion of the endoscope  1 . Further, the load on the motor will change significantly when both arms  4 ,  5  need to be driven together, as compared to the situation in which only the outer arm  4  needs to be driven. The speed of motion of the endoscope  1  is therefore likely to be different during the two phases of motion. 
     To address this problem, in preferred embodiments of the invention the inner and outer arms  4 ,  5  are geared so that, during tilt motion along axis  44  of the endoscope, both arms  4 ,  5  advance or retract simultaneously. 
     For instance, in moving from a situation in which both arms  4 ,  5  are fully retracted, in advantageous embodiments of the invention both arms  4 ,  5  are extended at an equal rate, until both arms  4 ,  5  reach the ends of their respective ranges of motion simultaneously. In other words, when the extension of the outer arm  4  with respect to the inner arm  5  is complete, the extension of the inner arm  5  with respect to the housing  7  will also be complete. 
     It will be appreciated that, using this technique, there will be no jerkiness or discontinuity when one telescopic element has finished advancing, and motion of another telescopic element begins. Further, the load on the motor will not vary significantly during any stage of the motion, since the same elements are being driven at all stages of motion. 
       FIG. 2  shows one possible gearing system  9  which could be used with the present invention. For clarity the gearing system  9  is shown driving motion in a straight, linear direction, but it will be appreciated that the components may readily be adapted for driving arcuate arms. A toothed main drive wheel  10  is provided, that may be driven directly by the motor  100 . The main drive wheel  10  is rotatable, but fixed in position. A first toothed rack  11  is provided in contact with the periphery of the main drive wheel  10 , and arranged such that rotation of the main drive wheel  10  will propel the first rack  11  in either a forward or backward direction. The inner arm  5  is connected to the first rack  11 , and it will be understood that rotation of the main drive wheel  10  will therefore act to extend or retract the inner arm  5  with respect to the housing  7 . 
     Contained, or substantially contained within the inner arm  5 , is a toothed belt  12 , which passes around a pair of freely rotatable wheels  13   a ,  13   b . A fixed cog  14  is attached to the housing  7 , and which does not rotate. The wheels  13   a ,  13   b  are positioned such that, regardless of the position of extension or retraction of the inner arm  5  with respect to the housing  7 , the fixed cog  14  is always in contact with a part of the toothed belt  12 . It will be understood that the toothed belt  12  therefore extends substantially the entire length of the inner arm  5 . 
     It will be appreciated that, as the inner arm  5  extends from the housing  7 , the toothed belt  12  will rotate with respect to the wheels  13   a ,  13   b  on which it is mounted. This is because the wheels  13   a ,  13   b  will move with respect to the fixed cog  14 , whereas the portion of the toothed belt  12  that contacts the fixed cog  14  will not be free to move with respect to the fixed cog  14 . The wheel  13   a  which is closest to the end of the inner arm  5  which is furthest from the housing  7  when inner arm  5  is extended will therefore rotate as the inner arm  5  is extended away from the housing  7 . 
     A secondary drive cog  15  is attached to the axle around which the wheel  13   a  turns, and this secondary drive wheel  15  is adapted to engage a second rack  16 , to which the outer arm  4  is attached. As the secondary drive wheel  15  rotates, the second rack  16 , and hence the outer arm  4 , may be driven in an extending or retracting motion relative to the inner arm  5 . 
     With reference to the arrangement depicted in  FIG. 2 , it can be understood that, when the inner arm  5  is driven to extend away from the housing  7 , the outer arm  4  will simultaneously be driven to extend away from the inner arm  5 . Correspondingly, when the inner arm  5  is driven to retract into the housing  7 , the outer arm  5  would be driven to retract into the inner arm  5 . 
     Referring to  FIG. 3 , an alternative gearing system  28  is shown. The alternative gearing system  28  comprises a fixed housing  17 , to which a pinion wheel  18  is attached. The pinion wheel  18  may be rotatably driven by a motor  100 . A third toothed rack  19  is slidably mounted with respect to the housing  19  so that teeth  20  of the third rack engage with the teeth  21  of the pinion wheel  18 . Rotation of the pinion wheel  18  will therefore cause translational motion of the third rack  19  with respect to the housing  17 . 
     The third rack  19  has a protrusion  22  which extends away from the third rack  19 , substantially away from the toothed face of the third rack  19 . A further pinion wheel  23  is rotatably mounted on the protrusion  22 . 
     An array of teeth  24  are provided on the housing  17 , arranged such that the teeth  25  of the further pinion wheel  23  mesh with the array of teeth  24 . It will therefore be appreciated that, as the third rack  19  moves with respect to the housing  17 , the engagement of the array of teeth  24  that are provided on the housing and the teeth  25  of the further pinion wheel  23  will cause the further pinion wheel  23  to rotate. 
     Finally, a fourth toothed rack  26  is slidably mounted with respect both to the housing  17  and to the third rack  19 , and is arranged so that teeth  27  of the fourth rack engage with the teeth  25  of the further pinion wheel  23 . It will be appreciated that rotation of the further pinion wheel  23  will therefore cause a translational motion of the fourth rack  26  with respect to the third rack  19 . Thus, rotation of the pinion wheel  23  will cause translational motion of the third rack  19  with respect to the housing  17 ; and motion of the fourth rack  26  with respect to the third rack  19 . 
     It will be understood that the further gearing system  28  could be used in connection with the invention, with, for example, motion of the inner arm  4  being controlled by movement of the third rack  19 , and movement of the outer arm  5  being controlled by a motion of the fourth rack  26 . 
     The skilled person will, however, realize that many other types of drive arrangements are possible, and the invention is not limited to the arrangement described above. 
     Whilst the above example is given with two telescopic elements, the skilled person will readily envisage that a similar arrangement could be put in place with three or more telescopic stages.  FIG. 4  shows an example telescopic drive having a third telescopic stage  29  in addition to inner and outer arms  5 ,  4 . 
     Further, while the above-described embodiment includes an arcuate telescopic arm, it will be appreciated that the invention may equally apply to a linear telescopic drive, or indeed any other type of telescopic drive. 
     It will be appreciated that the present invention provides a simple and robust solution to the problems described above, and will find utility in many fields. 
     When used in this specification and claims, the terms “comprises” and “comprising” and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components. 
     The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilized for realizing the invention in diverse forms thereof.