Multi-color multi-speed printing apparatus with circulation

1. A printer system, comprising, for each of one or more ink color groups:

a first primary ink tank holding a dark-colored ink;

a second primary ink tank holding a light-colored ink;

a first selector valve configured to change a state according to a print mode of the system;

a first secondary ink tank connected to the first primary ink tank via the first selector valve, the first secondary ink tank configured to store the dark-colored ink and to provide the dark-colored ink to a first set of print heads;

a second secondary ink tank connected to the first and second primary ink tanks via the first selector valve, the second secondary ink tank configured to store either the dark-colored ink or the light-colored ink and to provide the dark-colored ink or the light-colored ink to a second set of print heads according to the state of the first selector valve;

a second selector valve connected to the first primary ink tank configured to return the dark-colored ink from the first or the second set of print heads to the first primary ink tank; and

a third selector valve connected to the second selector valve and the second primary ink tank configured to either return the light-colored ink from the second set of print heads to the second primary ink tank or to direct the dark-colored ink to the second selector valve.

2. The system of claim 1 , wherein the second selector valve comprises a three-way solenoid.

3. The system of claim 1 , wherein the third selector valve comprises a three-way solenoid.

4. The system of claim 1 , comprising a control device coupled to the third selector valve, the control device configured to:

initiate, based on the print mode of the system, a changeover process for switching an ink stored in the second secondary ink tank; and

operate the third selector to perform the changeover process.

5. The system of claim 4 , wherein the changeover process comprises:

drawing an existing ink from the second secondary ink tank to a corresponding primary tank;

purging the existing ink from the second secondary ink tank;

filling the second secondary ink tank with a different ink;

flushing the second secondary ink tank and corresponding ink lines using the different ink; and

circulating the second secondary ink tank and the corresponding ink lines to remove remaining air.

6. The system of claim 5 , wherein the existing ink is the dark-colored ink, and wherein the changeover process further comprises:

filling and flushing the second secondary ink tank and the corresponding ink lines again using the different ink.

7. The system of claim 1 , further comprising:

a first tertiary ink tank connected to the first set of print heads to draw the dark-colored ink from the first set of print heads; and

a second tertiary ink tank connected to the second set of print heads to draw the light-colored ink or the dark-colored ink from the second set of print heads.

8. The system of claim 1 , further comprising:

a degasser positioned between a primary ink tank and a corresponding secondary tank configured to provided degassed ink to the corresponding secondary tank.

9. The system of claim 1 , wherein the one or more ink color groups comprise at least a black color group, a yellow color group, a cyan color group, or a magenta color group.

10. The system of claim 1 , wherein the one or more ink color groups further comprise a white color group.