A known liquid ejection apparatus (e.g., a liquid droplet ejection head) includes a nozzle plate having nozzles formed thereon, a channeled substrate including channels, e.g., pressure chambers configured to fluidly communicate with the corresponding nozzles, and piezoelectric elements to eject ink from the corresponding nozzles.
In the known liquid ejection apparatus, a vibration plate is provided on the channeled substrate to cover the pressure chambers. The piezoelectric elements are provided on the vibration plate to oppose the corresponding pressure chambers. A seal portion configured to cover the piezoelectric elements is provided on the vibration plate. The piezoelectric elements are sealed from an external space by the seal portion.
Each piezoelectric element includes an individual electrode (e.g., an upper electrode film). A connection terminal is connected to each individual electrode of the piezoelectric elements. The connection terminal extends from the piezoelectric element to an exterior of the seal portion in a surface of the vibration plate. A flexible wiring board or flexible printed circuit board on which a drive circuit is mounted, is connected to the connection terminals provided on a surface of the vibration plate in correspondence with respective piezoelectric elements. The drive circuit is configured to apply voltage to the respective piezoelectric elements, via wirings of the flexible wiring board, based on an instruction from an external controller.
To ensure electrical connection between the connection terminals and the flexible wiring board when the connection terminals are connected to the flexible wiring board by pressing the flexible wiring board against the connection terminals, each connection terminal needs to have a certain area. In a structure in which the connection terminal extending from each piezoelectric element is provided on a surface of the vibration plate, a greater surface area may be required for the vibration plate to ensure that sufficient area is provided for the connection terminals. However, this additional surface area will lead to increase in the size of the liquid ejection apparatus. Especially, in the field of printers, there is a trend to increase the number of nozzles recently. In association with the trend, the numbers of the piezoelectric elements and the connection terminals are increased, which will lead to further increase in the size of the liquid ejection apparatus.