Sequence control of color change

Claim 1

An automatic quick-change system for replacing an old coating liquid with a new coating liquid in an apparatus for selectively depositing a coating liquid on a sub-strate, said system comprising: a. a discharge gun having an input port, an exhaust port, a passage therein communicating with said input and exhaust ports, a nozzle, a check valve connected between said passage and said nozzle for connecting said nozzle to said passage when said check valve is opened; b. an exhaust line; c. a fluid-controlled dump valve having a pilot port and connected between said gun exhaust port and said exhaust line for connecting said gun exhaust port to said exhaust line in response to control pressure at said dump valve pilot port; d. a manifold having an output port, a solvent input port, an elongated passage therein communicating with said output port and said solvent port, and a plurality of coating liquid input ports communicating with said manifold passage intermediate said output and said solvent input ports; e. a feed line connected between said manifold output port and said gun input port; f. a source of pressurized solvent; g. a fluid-controlled solvent valve having a pilot port and connected between said solvent source and said solvent input port of said manifold for connecting said solvent source to said manifold input port in response to control pressure at said solvent valve pilot port; h. a plurality of sources of different pressurized coating liquids; i. a plurality of fluid-controlled coating liquid valves each having a pilot port and each connected to a different one of said coating liquid sources and a different one at said one of said sources with said one of said ports in response to control pressure at said coating liquid valve pilot port; j. a fluid control circuit including: 1. a source of pressurized control fluid, 2. a fluid timing circuit, 3. a variable pressure regulator connected between said control pressure source and said timing circuit, 4. a main valve connected between said regulator and said timing circuit for opening and closing a path therebetween, 5. a selector valve having a plurality of output ports each connected to the pilot port of a different one of said coating liquid valves, an input port selectively connectable to any one of said output ports for selecting said new coating liquid, 6. said timer comprising a plurality of fluid-actuated timing valves connected in sequence, each of said valves having a. a first output port, a second output port, a pilot port, and an input port normally connected to said first output port and alternatively connectable to said second output port in response to control pressure at said pilot port, b. a variable restriction valve connected between said timing valve input port and said pilot Port for communicating control pressure to said pilot port at some delayed time after pressure is applied to said input port, said delay time being variable by the combined settings of said restriction valve and said regulator, c. said plurality of timing valves including: 1. first fluid-controlled timing valve having its input port communicating with the output port of said main valve, its first output port communicating with the pilot port of said solvent valve and with the pilot port of said dump valve, and its second output port communicating with the input port of said selector valve for communicating control pressure to said pilot ports in accordance with the positions of said first timing valve and said main valve, 2. a second fluid-controlled timing valve having its input port communicating with the second output port of said first valve, its first output port communicating with the pilot port of said dump valve for communicating control pressure to said pilot port in accordance with the positions of said first and second timing valves and said main valve.