Circulator and liquid ejector

A liquid circulator, comprising:

• an upstream tank having a first pressure sensor;
• a downstream tank having a second pressure sensor;
• an intermediate tank connected to the upstream tank and the downstream tank via a circulation route for circulating liquid through an liquid ejecting head, the downstream tank, the intermediate tank, and the upstream tank;
• a first pump on the circulation route between the intermediate tank and the upstream tank;
• a second pump on the circulation route between the downstream tank and the intermediate tank;
• a first drive circuit configured to apply a first driving pulse to the first pump;
• a second drive circuit configured to apply a second driving pulse to the second pump;
• a controlling unit configured to:
• calculate a pressure fluctuation value of the circulation route based on pressure values measured by the first pressure sensor and the second pressure sensor;
• and
• adjust a phase difference between the first driving pulse and the second driving pulse as to minimize the pressure fluctuation value, wherein
• the first driving pulse and the second driving pulse are direct current (DC) pulses applied at different timings having a difference corresponding to the adjusted phase difference.

A liquid ejector, comprising:

• an ink ejecting head configured to eject ink onto recording medium, the ink ejecting head having a supply port for receiving ink and a recovery port for removing ink;
• an upstream tank having a first pressure sensor;
• a downstream tank having a second pressure sensor;
• an intermediate tank connected to the upstream tank and the downstream tank via a circulation route through which ink circulates through the ink ejecting head, the downstream tank, the intermediate tank, and the upstream tank;
• a first pump on the circulation route between the intermediate tank and the upstream tank;
• a second pump on the circulation route between the downstream tank and the intermediate tank;
• a first drive circuit configured to apply a first driving pulse to the first pump;
• a second drive circuit configured to apply a second driving pulse to the second pump;
• and
• a controlling unit configured to:
• calculate a pressure fluctuation value of the circulation route based on pressure values measured by the first pressure sensor and the second pressure sensor;
• and
• adjust a phase difference between the first driving pulse and the second driving pulse as to minimize the pressure fluctuation value, wherein
• the first driving pulse and the second driving pulse are alternating current (AC) pulses.

A liquid ejector, comprising:

• an ink ejecting head configured to eject ink onto recording medium, the ink ejecting head having a supply port for receiving ink and a recovery port for removing ink;
• an upstream tank having a first pressure sensor;
• a downstream tank having a second pressure sensor;
• an intermediate tank connected to the upstream tank and the downstream tank via a circulation route through which ink circulates through the ink ejecting head, the downstream tank, the intermediate tank, and the upstream tank;
• a first pump on the circulation route between the intermediate tank and the upstream tank;
• a second pump on the circulation route between the downstream tank and the intermediate tank;
• a first drive circuit configured to apply a first driving pulse to the first pump;
• a second drive circuit configured to apply a second driving pulse to the second pump;
• and
• a controlling unit configured to:
• calculate a pressure fluctuation value of the circulation route based on pressure values measured by the first pressure sensor and the second pressure sensor;
• and
• adjust a phase difference between the first driving pulse and the second driving pulse as to minimize the pressure fluctuation value, wherein
• the first driving pulse and the second driving pulse are direct current (DC) pulses applied at different timings having a difference corresponding to the adjusted phase difference.

A method for circulating liquid on a circulation route, comprising:

• measuring a first pressure value in an upstream tank;
• measuring a second pressure value in a downstream tank;
• applying a first driving pulse to a first pump to move liquid along a portion of a circulation route between an intermediate tank and the upstream tank;
• applying a second driving pulse to a second pump to move liquid along a portion of the circulation route between the downstream tank and the intermediate tank;
• calculating a pressure fluctuation value of the liquid in the circulation route based on the first pressure value and the second pressure value;
• and
• adjusting a phase difference between the first driving pulse and the second driving pulse to minimize the pressure fluctuation value, wherein
• the first driving pulse and the second driving pulse are alternating current (AC) pulses.

A method for circulating liquid on a circulation route, comprising:

• measuring a first pressure value in an upstream tank;
• measuring a second pressure value in a downstream tank;
• applying a first driving pulse to a first pump to move liquid along a portion of a circulation route between an intermediate tank and the upstream tank;
• applying a second driving pulse to a second pump to move liquid along a portion of the circulation route between the downstream tank and the intermediate tank;
• calculating a pressure fluctuation value of the liquid in the circulation route based on the first pressure value and the second pressure value;
• and
• adjusting a phase difference between the first driving pulse and the second driving pulse to minimize the pressure fluctuation value, wherein
• the first driving pulse and the second driving pulse are direct current (DC) pulses applied at different timings having a difference corresponding to the adjusted phase difference.