Ricoh Company, Ltd.

Yuu Kimura

Takahiro Yoshida

Atsushi Yanaka

A liquid ejection head includes a nozzle plate, a channel plate, a common-liquid-chamber member, and a deformable damper area. The nozzle plate includes plural nozzles to eject droplets of liquid. The channel plate includes individual liquid chambers communicated with the nozzles. The common-liquid-chamber member includes a common liquid chamber to supply the liquid to the individual liquid chambers. The deformable damper area forms a wall face of the common liquid chamber. The channel plate has an end in a direction perpendicular to a nozzle array direction in which the nozzles are arrayed. The end is opposed to a portion of the damper area and has a relief at a side facing the damper area to permit deformation of the damper area.

Liquid ejection head and image forming apparatus including same

A head drive control unit generates and outputs a pulse formed of a first expansion waveform element to expand individual liquid chambers, a first contraction waveform element to contract the individual liquid chambers, a second expansion waveform element to expand the individual liquid chambers, and a second contraction waveform element to return the individual liquid chambers that have repeatedly expanded and contracted to an initial state. The first contraction waveform element serves as a waveform element that contracts the individual liquid chambers at a timing of resonance with a change in a pressure in the individual liquid chambers due to the first expansion waveform element. The second contraction waveform element serves as a waveform element that suppresses the change in the pressure in the individual liquid chambers.

Image forming apparatus and head drive control method

A liquid ejection head includes a nozzle plate having a plurality of nozzles formed therein from which droplets are ejectable. The nozzle plate includes a nozzle substrate in which a plurality of nozzle holes each constituting a nozzle is formed, and a liquid-repellent film formed on a surface of the nozzle substrate on a droplet ejection side of the nozzle plate and on an inner wall of the nozzle on at least the droplet ejection side of the nozzle plate. A number of liquid-repellent groups per unit area in the liquid-repellent film formed on the inner wall of the nozzle decreases continuously from the droplet ejection side of the nozzle plate to a side opposite the droplet ejection side of the nozzle plate.

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Kanagawa, Japan

Yuu Kimura