1.  Field of the Invention
The present invention relates generally to medical devices and methods.  More particularly, the present invention relates to surgical tool systems for endoscopic and laparoscopic procedures where a single tool shaft can be used with multiple surgical tool tips. 
Laparoscope and other endoscopic surgical procedures are widely used and have replaced many open surgical procedures.  Laparoscopic procedures are performed within body cavities, such as the abdomen or thorax, and rely on introducing a shaft through a small incision, trocar or other access point through tissue which provide access into the cavity.  In laparoscopic procedures, the shaft manipulates a tool or end effector to perform a surgical protocol while viewing the surgical field within the cavity using a camera.  One drawback in performing laparoscopic and other endoscopic procedures is the need to frequently exchange tools through a limited number of access points. 
It has been proposed to increase the efficiency of laparoscopic and other endoscopic procedures by introducing a plurality of surgical tool tips into the surgical field, such as an insufflated abdomen or thorax, and subsequently exchanging tools on a single or limited number of tool shafts, thus avoiding the need to remove and exchange complete tools through the access points.  Such surgical tools exchange systems and procedures are described, for example, in commonly owned U.S. Patent Publication No.  2013/0150871, the full disclosure which is incorporated herein by reference. 
2.  Background Art
U.S. Patent Publication 2013/0150871 has been described above.  See also U.S. Pat.  Nos.  5,925,002; 6,309,397; and 7,492,116; as well as U.S. Publication Nos.  2003/0114731; 2005/0043718; U.S. 2005/0209607; U.S. 2006/0041273; U.S. 2007/0198000; U.S. 2008/0108871; U.S. 2008/0147096; US.  2008/0167672; U.S. 2008/0275480; U.S 2009/0005638; and U.S. 2013/0066304.