Planar Systems Inc., a developer of flat-panel display systems, has announced changes to its board of directors: Balaji Krishnamurthy, a board member and Planar's president and CEO since 1999, became chairman of the board effective Jan. 31. Gregory H. Turnbull, a director since 1986, will assume the new role of lead independent director. William D. Walker, a director of the company since its inception in 1983 and its chairman since 1988, will continue to serve as a board member.