RISO Technologies

A liquid ejection head includes a nozzle plate extending in a first direction and having a nozzle for ejecting a liquid, and a plurality of flow path substrates extending in the first direction and each having an opening or a groove by which a pressure chamber communicating with the nozzle and a resistance flow path communicating with the pressure chamber are formed. At least one of the flow path substrates includes a first reinforcing wall portion at a location at which the pressure chamber is formed. In the first direction, a distance between one end of the first reinforcing wall portion that is closer to the nozzle than the other end and an edge of the nozzle that is closest to the one end of the first reinforcing wall portion is 75 µm to 175 µm.

A liquid ejection head includes nozzles for ejecting a liquid, pressure chambers communicating with the nozzles, a supply-side flow path, an ejection-side flow path, and piezoelectric elements. When a viscous resistance of each nozzle is Rn, an inertial resistance of each nozzle is Mn, a meniscus compliance of each nozzle is Cn, viscous and inertial resistances of the supply-side flow path are Rm1 and Mml, viscous and inertial resistances from the supply-side flow path to each nozzle are Rc1 and Mc1, viscous and inertial resistances from each nozzle to the ejection-side flow path are Rc2 and Mc2, and resistance and inertial resistances of the ejection-side flow path are Rm2 and Mm2, and M=Mn+1/(1/Mc1+1/Mc2)+1/(1/Mm1+1/Mm2), R=Rn+1/(1/Rc1+1/Rc2)+1/(1/Rm1+1/Rm2), ω=(M×C<n>)<-1/2>, and γ=R/2/M, 0.2≤γ<2>/ω<2>≤1.0 is satisfied.

A liquid ejection head includes a nozzle plate that includes a plurality of nozzles through which liquid is ejected in a first direction, the nozzle plate having a first surface that faces the first direction and a second surface opposite to the first surface, a nozzle cover that faces the first surface of the nozzle plate and has openings at locations corresponding to the nozzles, and a flow path member that contacts the second surface of the nozzle plate and forms one or more flow paths of the liquid that communicate with the nozzles. The nozzle plate is flexible and includes: a damper portion that extends across one of the flow paths, and a bonding portion that is bonded to the flow path member. The nozzle cover is bonded to the nozzle plate at a location other than the damper portion of the nozzle plate.

A liquid ejection head includes pressure chambers arranged in a first direction, each pressure chamber storing liquid, pairs of upstream and downstream flow paths, each pair communicating with a corresponding one of the pressure chambers, an upstream common chamber communicating with the upstream flow paths, an upstream port communicating with the upstream common chamber, a downstream common chamber communicating with the downstream flow paths, a downstream port communicating with the downstream common chamber, a bypass flow path connected between, and communicating with, the upstream and downstream common chambers, a bypass resistance flow path that communicates with the bypass flow path, and one or more pressure dampers including a first damper region located upstream side of the bypass resistance flow path and a second damper region located downstream side of the bypass resistance flow path.

A liquid ejection head includes pressure chambers arranged in a first direction and storing liquid, pairs of upstream and downstream flow paths, each pair communicating with a corresponding one of the pressure chambers, an upstream common chamber communicating with the upstream flow paths, an upstream port communicating with the upstream common chamber, a downstream common chamber communicating with the downstream flow paths, a downstream port communicating with the downstream common chamber, and a bypass flow path communicating with the upstream and downstream common chambers. Each of the upstream flow paths is inclined in a direction against a flow of the liquid in the upstream common chamber, and each of the downstream flow paths is inclined in a direction against a flow of the liquid in the downstream common chamber.

A liquid ejection head includes a nozzle plate including a nozzle, a pressure chamber that is capable of storing liquid and communicates with the nozzle, a volume of the pressure chamber being varied to eject the liquid from the nozzle, an actuator configured to vary the volume of the pressure chamber in response to a drive signal, and a drive circuit configured to generate the drive signal that includes a plurality of ejection waveforms. One of the ejection waveforms follows a preceding ejection waveform after an intermediate time period. The drive circuit is configured to set the intermediate time period based on an ejection speed of the liquid that is 0.2 times or more and 2 times or less of a half cycle of a natural vibration period of the liquid in the pressure chamber.

A liquid ejection head includes a nozzle, a pressure chamber that communicates with the nozzle, a volume of the chamber being varied to eject liquid from the nozzle, an actuator configured to vary the volume in response to a drive signal, and a drive circuit configured to generate the signal. The signal includes n ejection waveforms each including an ejection pulse including an expansion portion and a contraction portion. At least one of the ejection waveforms includes a damping pulse that is subsequent to the ejection pulse and includes a contraction portion and an expansion portion. The ejection waveforms include consecutive ejection waveforms that are separated by an intermediate time period that is in a range of 0.2 times or more and 2 times or less a half cycle of a natural vibration period of the liquid in the chamber.

An inkjet head includes a plurality of actuators each configured to eject ink through a corresponding one of nozzles, the actuators including first actuators corresponding to first nozzles that are enabled to eject ink and second actuators corresponding to second nozzles that are disabled from ejecting ink, a drive circuit configured to drive the actuators in accordance with input data, and a data transfer circuit configured to: acquire first image data associating each of the first nozzles with images to be formed, add, to the first image data, dummy image data associated with the second nozzles, and output the first image data to which the dummy image data has been added to the drive circuit as the input data.

A liquid ejection head includes pressure chambers arranged in a first direction and respectively communicating with nozzles, pairs of upstream and downstream flow paths extending in a second direction different from the first direction, each pair communicating with a pressure chamber, the upstream path connected to a first end of the corresponding chamber, and the downstream path of said each pair connected to a second end of the chamber, an upstream common chamber communicating with the upstream paths, a downstream common chamber communicating with the downstream paths, and a bypass flow path communicating with the upstream chamber at an end thereof and the downstream chamber at an end thereof. Each upstream path has an inlet connected to the upstream chamber and an outlet connected to the corresponding chamber, the inlet widening toward the end of the upstream chamber.

A liquid ejection head includes pressure chambers arranged in a first direction and respectively communicating with nozzles, each pressure chamber capable of storing liquid, pairs of upstream and downstream flow paths, each pair communicating with a pressure chamber, an upstream common chamber communicating with the upstream flow paths, a downstream common chamber communicating with the downstream flow paths, and a bypass flow path communicating with the upstream and downstream common chambers. A circulation flow rate of the liquid is greater than or equal to a maximum total ejection flow rate of the liquid ejected from the nozzles. The circulation flow rate is a flow rate at which the liquid flowing through the upstream flow paths to the downstream flow paths when a flow rate of the liquid entering from the upstream port is substantially equal to a flow rate of the liquid exiting through the downstream port.