Abstract: A liquid discharge head includes a nozzle plate having nozzles arrayed to discharge liquid droplets; a passage plate to form individual liquid chambers communicating with the respective nozzles; and a wall surface member to form a wall surface of the individual liquid chambers. The passage plate is formed with at least three plate-shaped members stacked and bonded by an adhesive. The nozzle plate and one plate-shaped member, and another plate-shaped member and the wall surface member are bonded, respectively. The three plate-shaped members include separation wall parts forming separation walls between the individual liquid chambers. At least one of the three plate-shaped members has a separation wall width different from that of the others, to have fillets of the forced-out adhesive formed between the wall surfaces, and surfaces of the plate-shaped members, the nozzle plate, or the wall surface member.

Abstract: A liquid ejection head is provided. The liquid ejection head includes at least two nozzle lines configured to have a plurality of nozzles for ejecting liquid disposed in respective lines, a plurality of individual liquid chambers configured to be in communication with corresponding nozzles of the nozzle lines, and at least two circulation channels corresponding to the nozzle lines, configured to be in communication with the individual liquid chambers. The at least two circulation channels are in communication with each other through a bridging channel disposed in a direction intersecting with the nozzle line direction, and the bridging channel and the circulation channels are disposed at different positions in a thickness direction of a member which forms the bridging channel and the circulation channels.

Abstract: A disclosed liquid-ejection head for ejecting liquid droplets includes a substrate having a diaphragm forming a part of walls of a pressure liquid chamber, and a piezoelectric element adhered to the substrate with adhesive, and configured to apply pressure to the pressure liquid chamber via the diaphragm. The piezoelectric element has a surface facing the substrate having the diaphragm, and the surface has one or more projection parts in an area in which the pressure liquid chamber is not disposed, and whereon the substrate having the diaphragm has one or more recess parts that fit in the respective projection parts.

Abstract: A disclosed liquid-ejection head for ejecting liquid droplets includes a substrate having a diaphragm forming a part of walls of a pressure liquid chamber, and a piezoelectric element adhered to the substrate with adhesive, and configured to apply pressure to the pressure liquid chamber via the diaphragm. The piezoelectric element has a surface facing the substrate having the diaphragm, and the surface has one or more projection parts in an area in which the pressure liquid chamber is not disposed, and whereon the substrate having the diaphragm has one or more recess parts that fit in the respective projection parts.

Abstract: A liquid discharge head includes a nozzle plate having nozzles arrayed to discharge liquid droplets; a passage plate to form individual liquid chambers communicating with the respective nozzles; and a wall surface member to form a wall surface of the individual liquid chambers. The passage plate is formed with at least three plate-shaped members stacked and bonded by an adhesive. The nozzle plate and one plate-shaped member, and another plate-shaped member and the wall surface member are bonded, respectively. The three plate-shaped members include separation wall parts forming separation walls between the individual liquid chambers. At least one of the three plate-shaped members has a separation wall width different from that of the others, to have fillets of the forced-out adhesive formed between the wall surfaces, and surfaces of the plate-shaped members, the nozzle plate, or the wall surface member.