Equipment to Measure and Control Synchronization Errors in 3-D Projection
K. Clark Jones, William A. Shurcliff · Journal of the Society of Motion Picture and Television Engineers · 1954
Equipment is described that permits the projectionist to obtain and maintain perfect synchronism in the projection of 3-D motion pictures. This is accomplished without stopping the show or otherwise interfering with the continuity and quality of the projection. The equipment is of two basic types: synchronization monitors and synchronization controls. The monitor is used to measure the direction and amount of the synchronization error, and the control is then used to correct the error.