Instruments

Abstract

An instrument including an elongate portion having a first part movable from a first configuration to a second, different configuration and a second part, at a different elongate extent along the elongate portion than the first part, movable from a first configuration to a second, different configuration, at least one of the parts including a control whereby a force required to move the first part from the first configuration towards the second configuration is less than the force required to move the second part from the first configuration towards the second configuration. A method of using the instrument.

1 . An instrument including an elongate portion having a first part movable from a first configuration to a second, different configuration and a second part, at a different elongate extent along the elongate portion than the first part, movable from a first configuration to a second, different configuration, at least one of the parts including a control whereby a force required to move the first part from the first configuration towards the second configuration is less than the force required to move the second part from the first configuration towards the second configuration. 
     
     
         2 . An instrument as claimed in  claim 1  in which at least one control includes a flexible member arranged to exert a bias against movement of the part that includes that control from the first to the second position. 
     
     
         3 . An instrument as claimed in  claim 1  in which at least one end of at least one control is arranged to slide in the longitudinal direction relative to a portion of the elongate member which is coaxial to that end when the part that includes that control is moved from the first configuration towards the second configuration. 
     
     
         4 . An instrument as claimed in  claim 3  in which at least one end of at least one control is prevented from sliding in the longitudinal direction relative to a portion of the elongate member which is coaxial with that end when the part that includes that control is moved from the first configuration towards the second configuration and in which the end that is prevented from sliding is connected to the elongate portion at the location of the elongate portion that is coaxial with that end. 
     
     
         5 . An instrument as claimed in  claim 1  in which at least one control is capable of moving in the longitudinal direction of the elongate portion relative to the elongate portion when the part associated with that control is in the first configuration and in which at least one end region of the control cooperates with the elongate portion to restrict movement of the control in both directions of the elongate extent. 
     
     
         6 . An instrument as claimed in  claim 5  in which the distance between the end regions of the control that restrict sliding movement of the control is arranged such that they do not simultaneously cooperate with the elongate portion when the part that includes that control is moved from the first towards the second configuration. 
     
     
         7 . An instrument as claimed in  claim 5  in which the distance between the end regions of the control co-operate with the elongate portion when the part that includes that control moves to the second configuration whereby the distance between the end regions defines the limit of movement from the first configuration to the second configuration. 
     
     
         8 . An instrument as claimed in  claim 1  in which each part includes a control whereby the force required to move the first part from the first configuration towards the second configuration is less than the force required to move the second part from the first configuration towards the second configuration. 
     
     
         9 . An instrument as claimed in  claim 1  in which the or each control is arranged to assist in returning the first and second parts from the second configuration towards the first configuration. 
     
     
         10 . An instrument as claimed in  claim 9  in which the second part is arranged to start to move from the second configuration towards the first configuration at a greater force than the force required to allow the first part to start to move from the second configuration towards the first configuration. 
     
     
         11 . An instrument as claimed in  claim 1  in which the elongate portion includes at least three parts at different elongate extents along the elongate portion each movable from a first to a second, different configuration each having a control in which a force required to move the parts from the first towards the second configuration is different in the at least three parts. 
     
     
         12 . An instrument as claimed in  claim 1  including an actuator arranged to urge the first and second parts from the first to the second positions, the actuator comprising at least one wire extending along the elongate portion which wire is arranged to be tightened to effect movement from the first to the second configuration. 
     
     
         13 . An instrument as claimed in  claim 12  in which the actuator is arranged to urge the first and second parts from the first to the second configuration at the same time and, when the first and second parts are in the first configuration, to exert an equal bias on the parts to urge them away from the first configuration. 
     
     
         14 . An instrument as claimed in  claim 1  in which at least the first part includes at least a gap along a side of the elongate portion which gap, in use, is arranged to be at least partially closed when the first part is moved from the first towards the second configuration. 
     
     
         15 . An instrument as claimed in  claim 14  in which the or each gap of that part is arranged to be at least partially closed before the second part starts to move from the first towards the second configuration. 
     
     
         16 . An instrument as claimed in  claim 15  in which the or each gap of the first part is arranged to be completely closed before the second part starts to move from the first towards the second configuration. 
     
     
         17 . An instrument as claimed in  claim 14  in which the or each gap is defined between two, separate segments. 
     
     
         18 . An instrument including an elongate portion comprising:
 a first part movable from a first configuration to a second, different configuration; and   a second part at a different elongate extend along the elongate portion than the first part movable from a first to a second, different configuration, at least one of the parts including a control, said control including a flexible member arranged to exert a bias against movement of the part that includes that control from the first to the second position, said control operating such that a force required to move the first part from the first configuration towards the second configuration is less than the force required to move the second part from the first configuration towards the second configuration and such that the second part is arranged to start to move from the second configuration towards the first configuration at a greater force than the force required to allow the first part to start to move from the second configuration towards the first configuration;   the instrument further including an actuator, said actuator being arranged to urge said first and second parts from the first to the second positions, the actuator comprising at least one wire extending along the elongate portion which wire extends along the elongate portion which wire is arranged to be tightened to effect movement of the parts from the first to the second configurations.   
     
     
         19 . A method of using an instrument comprising causing at least first and second parts of an elongate portion that are axially spaced from each other along the elongate portion to move from a first configuration to a second, different configuration and causing the first part to move from the first configuration towards the second configuration and then the second part to start to move from the first configuration towards the second configuration by the first part being less resistant to a force causing movement from the first configuration to the second configuration than a force causing the second part to move from the first configuration towards the second configuration. 
     
     
         20 . A method claimed in  claim 19  comprising, when the first and second parts are in the second configuration, reducing the force simultaneously on each part holding them in that configuration and causing the control in at least one part to cause the second part to start to move from the second configuration towards the first configuration before the first part starts to move from the second configuration towards the first configuration.