Patent ID: 6443577
Filing Date: 2002-09-03
Classification: G03B,Y10S

Abstract:
An overhead projector comprising:a) a stage assembly; b) a post extending from the stage assembly; c) an optical projection head assembly suspended above the stage assembly by the post in a cantilever arrangement, the optical head assembly having a weight W; d) wherein the head assembly includes a post retaining assembly having a collar fitted around the post, the collar having at least two friction points interacting with the post, the interaction having a coefficient of friction &mgr;; e) wherein the weight W and the cantilever arrangement create torsional forces, the at least two friction points being positioned to transmit the torsional forces onto the post creating a friction force Ff, and f) wherein the coefficient of friction of the interaction between each of the at least two friction points and the post is selected such that absent other forces the friction force is at least sufficient to maintain the head assembly at a static position with respect to the post.