System and method for adjusting a working distance to correspond with the work surface

A system for controlling a distance between a tool and a workpiece in a manufacturing apparatus during a manufacturing process, the system comprising:

• means for sensing the distance between the tool and the workpiece;
• means for generating relative motion between the workpiece and the tool;
• first control means for controlling the means for generating based on a measurement of the means for generating to perform large scale relative movement of the tool with respect to the workpiece;
• and
• second control means for precisely controlling the means for generating based on the means for sensing to generate fine relative motion of the tool with respect to the workpiece, wherein:
• the manufacturing apparatus is a coating apparatus;
• the manufacturing process is a coating process;
• the tool is a dispenser that dispenses a fluid in the coating process;
• the workpiece is a substrate with a surface suitable for coating with the fluid;
• the distance is a gap between the dispenser and substrate;
• the means for generating relative motion comprises means for moving the dispenser with respect to a stationary substrate;
• and
• wherein the means for moving is an electric motor which has a position and the means for sensing the gap comprises a rotary encoder which measures the position of the electric motor.

A system for controlling a gap between a dispenser and a substrate in a coating apparatus during a coating process, the system comprising:

• a gap sensor for directly measuring said gap between said dispenser and said substrate;
• means for generating relative motion between said dispenser and said substrate;
• first control means for controlling said means for generating based on a measurement of said means for generating to generate large scale relative motion between said dispenser and said substrate;
• and
• second control means for precisely controlling the means for generating based on the gap sensor to generate fine relative motion of the dispenser with respect to the substrate, wherein the means for generating relative motion comprises means for moving the dispenser with respect to a stationary substrate and wherein the gap sensor measures a separation between a sensor mount located on the dispenser and a point on a surface of said substrate.