Printhead chip incorporating electro-magnetically operable ink ejection mechanisms

1. A printhead chip which comprises

a substrate that incorporates drive circuitry;

nozzle chamber structures that define nozzle chambers, ink inlets in fluid communication with the nozzle chambers and ink ejection ports in fluid communication with respective nozzle chambers;

ink ejecting members positioned in respective nozzle chambers, reciprocally displaceable with respect to the substrate to eject ink from the ink ejection ports, and responsive to a magnetic field of cyclically reversing polarity to be reciprocally displaced;

checking mechanisms operatively engageable with respective ink ejecting members selectively to check reciprocal displacement of the ink ejecting members, the checking mechanisms being connected to the drive circuitry to be operable on receipt of an electrical signal from the drive circuitry;

wherein each ink ejecting member is pivotally mounted on one side to a sidewall of the respective nozzle chamber, with each checking mechanism being oppositely oriented on the sidewall selectively to check reciprocal pivotal displacement of the ink ejecting member.

2. A printhead chip as claimed in claim 1 , in which the nozzle chamber structures are defined by the substrate, the ink inlets and the nozzle chambers being the result of an etching process carried out in the substrate from an inlet side of the substrate.

3. A printhead chip as claimed in claim 2 , in which the substrate is a silicon wafer substrate and the respective ink ejection ports are defined in an etch stop layer positioned on an ink ejection side of the substrate.

4. A printhead chip as claimed in claim 1 , in which each ink ejecting member is composed, at least in part, of a magnetic material.

5. A printhead chip as claimed in claim 1 , in which the checking mechanisms have obstruction members positioned in respective sidewalls, the obstruction members being displaceable out of and back into the sidewalls on receipt of electrical signals from the drive circuitry, respectively to obstruct and permit pivotal movement of the ink ejecting members.