Patent ID: 8534799

Claim:
A liquid discharge head, comprising: a liquid pressurizing chamber; a pressurizing unit that applies a pressure to the liquid pressurizing chamber, a liquid discharge hole; and a communication passage that connects the liquid pressurizing chamber and the liquid discharge hole, wherein the communication passage comprises a narrow portion having a small cross-section area, a first communication passage defined by a portion between a connection end to the liquid pressurizing chamber and a connection end to the narrow portion, and a second communication passage defined by a portion between a connection end to the liquid discharge hole and the connection end to the narrow portion, and a cross-section area of the narrow portion is 0.7 time or less of a cross-section area of the first communication passage, and is 0.7 time or less of a cross-section area of the second communication passage, and 0.2≦Ld 2 /Ld 0 ≦0.4, 0.17≦M 2 /M 1 ≦0.25, and 0.18≦C 2 /C 1 ≦0.23 are satisfied, where Ld 0 (m) is a length of the communication passage, Ld 2 (m) is a length of the second communication passage, M 1 (kg/m 4 ) is a combined inertance of the liquid pressurizing chamber and the first communication passage, C 1 (m 5 /N) is a combined compliance of the liquid pressurizing chamber and the first communication passage, M 2 (kg/m 4 ) is combined inertance of the liquid discharge hole and the second communication passage, and C 2 (m 5 /N) is combined compliance of the liquid discharge hole and the second communication passage.