Compact ink delivery in an ink pen

An ink pen for an inkjet printer, comprising:

• a first ink holding chamber having a filter therein separating the first ink holding chamber into an upstream sub-chamber and a downstream sub-chamber;
• an ink inlet through which ink may flow into the upstream sub-chamber of the first ink holding chamber;
• a second ink holding chamber downstream from the first ink holding chamber;
• an ink flow passage connecting the downstream sub-chamber of the first ink holding chamber and the second ink holding chamber;
• a pressure regulator in the second ink holding chamber;
• a flow control valve operative to open and close the ink flow passage in response to pressure changes in the second ink holding chamber;
• and
• a printhead downstream from and operatively connected to the second ink holding chamber.

A method implemented in an ink delivery system for an inkjet ink pen, the method comprising:

• chambering ink in the pen, wherein the pen comprises:
• an ink filter chamber;
• a pressure regulator chamber downstream from the ink filter chamber along a path of ink flow through the pen;
• a pressure regulator in the pressure regulator chamber;
• a filter in the ink filter chamber;
• an inlet to the ink filter chamber upstream from the filter along the ink flow path;
• an outlet from the ink filter chamber to the pressure regulator chamber downstream from the filter along the ink flow path such that ink flowing from the inlet to the outlet passes through the filter;
• and
• a flow control valve operative to open and close the outlet in response to pressure changes in the pressure regulator chamber;
• filtering the chambered ink;
• and then
• regulating the pressure of filtered ink.

A method implemented in an ink delivery system for an inkjet ink pen, the method comprising:

• providing the inkjet pen, the inkjet pen comprising:
• an ink filter chamber;
• a pressure regulator chamber downstream from the ink filter chamber along a path of ink flow through the pen;
• a pressure regulator in the pressure regulator chamber;
• a filter in the ink filter chamber;
• an inlet to the ink filter chamber upstream from the filter along the ink flow path;
• an outlet from the ink filter chamber to the pressure regulator chamber downstream from the filter along the ink flow path such that ink flowing from the inlet to the outlet passes through the filter;
• and
• a flow control valve operative to open and close the outlet in response to pressure changes in the pressure regulator chamber;
• pumping ink into the ink filter chamber at a first pressure;
• filtering ink in the ink filter chamber;
• selectively allowing filtered ink to flow from the ink filter chamber into a pressure regulator chamber;
• and
• pumping ink out of the pressure regulator chamber to a printhead at a second pressure lower than the first pressure.

An ink pen for separately ejecting two inks, the ink pen comprising:

• a first ink filter chamber located on a first side of a barrier that is impervious to ink;
• a first filter in the first ink filter chamber;
• a second ink filter chamber located on a second side of the barrier opposite the first side of the barrier;
• a second filter in the second ink filter chamber;
• a first pressure regulator chamber located on the second side of the barrier;
• a first pressure regulator in the first pressure regulator chamber;
• a second pressure regulator chamber located on the first side of the barrier;
• a second pressure regulator in the second pressure regulator chamber;
• a first ink inlet through which ink may enter the first ink filter chamber upstream from the first filter;
• a second ink inlet through which ink may enter the second ink filter chamber upstream from the second filter;
• a first ink flow passage through the barrier connecting the first ink filter chamber with the first pressure regulator chamber, the first ink flow passage located downstream from the first filter;
• a second ink flow passage through the barrier connecting the second ink filter chamber with the second pressure regulator chamber, the second ink flow passage located downstream from the second filter;
• a first flow control valve operative to open and close the first ink flow passage in response to pressure changes in the first ink regulator chamber;
• a second flow control valve operative to open and close the second ink flow passage in response to pressure changes in the second ink regulator chamber;
• a first printhead downstream from and operatively connected to the first pressure regulator chamber;
• and
• a second printhead downstream from and operatively connected to the second pressure regulator chamber.