Liquid discharge head, liquid discharge unit, and liquid discharge apparatus

1 . A liquid discharge head comprising:

multiple nozzles;

multiple individual chambers respectively communicating with the multiple nozzles;

a common chamber communicating with each of the multiple individual chambers;

multiple fluid restrictors between each of the multiple individual chambers and the common chamber; and

multiple actuators driven to cause a liquid in the multiple individual chambers to be discharged from the multiple nozzles,

a meniscus formed at each of the multiple nozzles has a natural period of vibration different from each of:

a resonant period of the common chamber;

half of the resonant period of the common chamber; and

a quarter of the resonant period of the common chamber.

2 . The liquid discharge head according to claim 1 ,

wherein the natural period of vibration of the meniscus defined as Tmr and the resonant period of the common chamber defined as Tk are obtained by following expressions (1) and (2), respectively:

Tmr= 2π√{( Lp+Lr+Lt+Ls )× Cm}   (1)

Tk= 2π×√( Lk×Ck )  (2)

where Lp=(6/5)×ρ×lp/sp,

Lr=(6/5)×ρ×lr/sr,

Lt=4×ρ×lt/(π×dt×ds)×1.45,

Ls=4×ρ×ls/(π×ds 2 )×1.45, and

Cm=π×ds 4 /(128×γ),

Lk=6/5×ρ×lk/sk, and

Ck=lk×sk/(ρ×c2)

where ρ represents a density of the liquid,

c represents a velocity of sound of the liquid,

lp represents a length of each of the multiple individual chambers in a liquid flow direction flowing from the multiple fluid restrictors to the multiple individual chambers, respectively,

sp represents a cross-sectional area perpendicular to the liquid flow direction of each of the multiple individual chambers,

lr represents a length of each of the multiple fluid restrictors in the liquid flow direction,

sr represents a cross-sectional area perpendicular to the liquid flow direction of the each of the multiple fluid restrictors,

lt represents a length of a tapered portion of each of the multiple nozzles,

ls represents a length of a straight portion of each of the multiple nozzles,

dt represents a maximum diameter of the tapered portion of each of the multiple nozzles,

ds represents a diameter of the straight portion of each of the multiple nozzles,

γ represents a surface tension of the liquid,

lk represents a length of the common chamber in an array direction in which the multiple individual chambers are arrayed, and

sk represents a cross-sectional area of the common chamber perpendicular to the array direction of the multiple individual chambers.

3 . The liquid discharge head according to claim 1 ,

wherein any of following conditions is satisfied:

Tmr/Tk≤ 0.22,

0.28≤ Tmr/Tk≤ 0.45,

0.55≤ Tmr/Tk≤ 0.9, and

1.1≤ Tmr/Tk

where the natural period of vibration of the meniscus is defined as Tmr, and the resonant period of the common chamber is defined as Tk.

4 . The liquid discharge head according to claim 3 ,

wherein any of following conditions is satisfied:

Tmr/Tk≤ 0.2,

0.3≤ Tmr/Tk≤ 0.4,

0.6≤ Tmr/Tk≤ 0.8, and

1.2≤ Tmr/Tk.

5 . A liquid discharge unit comprising the liquid discharge head according to claim 1 .

6 . A liquid discharge apparatus comprising the liquid discharge head according to claim 1 .