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(11) | EP 0 671 271 A3 |
(12) | EUROPEAN PATENT APPLICATION |
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(54) | Ink jet recording apparatus |
(57) An inkjet recording apparatus comprises an inkjet head (10) having for each of one
or more nozzles (4) an ink passage (7, 6) in communication with the nozzle (4) and
an electrostatic actuator. The actuator includes a diaphragm (5) provided at one part
(6) of the ink passage, a nozzle electrode (21) provided in opposition to the diaphragm
(5) with a gap (G) in between and a vibration chamber (9) having upper and lower walls
of which one wall is formed by one part of said diaphragm (5), while said nozzle electrode
is attached to the other wall. The diaphragm constitutes one and the nozzle electrode
(21) the other plate of a capacitor. Drive means selectively charge and discharge
each actuator such as to displace its diaphragm (5) by electrostatic force, thereby
to eject ink droplets from said one or more nozzles. Vibration chamber (9) is sealed
to be airtight. Its volume V is such that the ratio between this volume V and the
volume ΔV displaced by the diaphragm is within the range . This enables sufficient electrostatic attraction with a sealed actuator and without necessity to increase the drive voltage. |