A piezoelectric device includes a substrate on which a plurality of recesses are arranged in a first direction, a vibration plate, and a piezoelectric actuator having a first electrode, a second electrode and a third electrode, a fourth electrode, and a piezoelectric layer, in which a plurality of active portions are provided, the second electrode and the third electrode are provided from an edge of a region facing a recess to an outside of the recess, the first electrode is formed between the second electrode and the third electrode, the second electrode, the third electrode, and the fourth electrode configure common electrodes for the plurality of active portions, and the first electrode configures an individual electrode provided independently for each of the active portions.

The individual flow path includes a nozzle communicating with an outside, a first flow path, in the middle of which the nozzle is disposed and which extends in a first direction that is an in-plane direction of a nozzle surface of the nozzle plate in which the nozzle opens, a second flow path coupled to the first flow path and extending in a second direction other than the first direction, a third flow path coupled to the second flow path and extending in the third direction other than the second direction, and a pressure chamber which is disposed in the third flow path and in which a pressure change is induced by the energy generating element. A cross-sectional area of the first flow path is smaller than a cross-sectional area of the second flow path.

A MEMS device includes a first substrate 22 including a single-crystal silicon substrate and a second substrate 23 including a single-crystal silicon substrate, in which the first substrate 22 and the second substrate 23 are laminated together, and the first substrate 22 and the second substrate 23 are joined to each other such that the cleavage directions of both substrates intersect each other.

A liquid discharge head is configured to discharge a liquid, and the liquid discharge head includes an actuator substrate and a holding substrate bonded to the actuator substrate. The actuator substrate includes a pressure generator, and a wiring electrode configured to electrically connect the pressure generator and an exterior of the liquid discharge head. The holding substrate includes an opening configured to expose the wiring electrode to the exterior of the liquid discharge head, and a detection surface adjacent to the opening, the detection surface having a higher reflectance than a surface of the wiring electrode of the actuator substrate.

A liquid ejection device includes: a nozzle through which a liquid is ejected; a liquid transfer tube through which the liquid is transferred to the nozzle; and a vibration generation unit configured to generate vibration, in which the vibration generation unit is in contact with one of the liquid, the nozzle, and the liquid transfer tube, and when the liquid ejected from the nozzle flies as a plurality of droplets in a state where the vibration generation unit does not generate vibration, and the number of the droplets passing through a predetermined position in a unit time is defined as a droplet frequency, a frequency of the vibration generated by the vibration generation unit is equal to or less than the droplet frequency.

The interface region may include a region in which first intensity is higher than second intensity and in which the first intensity is higher than third intensity, where a degree of orientation of the (−211) crystal face of the second layer is denoted as the first intensity, the degree of orientation of the (−111) crystal face of the second layer is denoted as the second intensity, and the degree of orientation of the (002) crystal face of the second layer is denoted as the third intensity. The surface-layer region may include a region in which the first intensity is higher than the third intensity and in which the second intensity is higher than the third intensity.

A print head having an ejection portion that ejects a liquid includes a determination portion that executes a first determination process of determining whether or not a first error occurs in which replacement of the print head or replacement of a hardware coupled to the print head is required and a second determination process of determining whether or not a second error occurs in which neither the replacement of the print head nor the replacement of the hardware coupled to the print head is required, and a light emitting portion that emits light according to a result of determination in the determination portion.

There is provided a liquid discharge apparatus including: an amplifier circuit that outputs an amplified modulated signal by driving a transistor; a demodulation circuit that includes an inductance element and outputs the driving signal, in which the inductance element includes a first side portion provided with a first terminal, a second side portion positioned facing the first side portion and provided with the second terminal, a third side portion intersecting with the first side portion and the second side portion, a lead member coupled to the first terminal and the second terminal, and a shortest distance between the transistor and the third side portion is equal to or shorter than a shortest distance between the transistor and the first side portion, and is equal to or shorter than a shortest distance between the transistor and the second side portion.

A liquid discharge head unit includes a liquid discharge head that has a first detection resistor that is provided to correspond to a first piezoelectric element group, a second detection resistor that is provided to correspond to a second piezoelectric element group, a power supply circuit that causes a current to flow through the first detection resistor and the second detection resistor, a voltage detection circuit that detects a voltage, and a switching circuit that is configured to switch between a first state in which the voltage detection circuit is configured to detect a voltage generated in the first detection resistor due to the current flowing from the power supply circuit and a second state in which the voltage detection circuit is configured to detect a voltage generated in the second detection resistor due to the current flowing from the power supply circuit.

A liquid discharge head includes a pressure chamber substrate that has a plurality of pressure chambers, a piezoelectric element that is laminated at the pressure chamber substrate, and has an individual electrode individually provided for each of the plurality of pressure chambers, a common electrode commonly provided for the plurality of pressure chambers, and a piezoelectric body provided between the individual electrode and the common electrode in a lamination direction of the piezoelectric element and provided to apply pressure to a liquid in the pressure chamber, a drive wiring that is electrically coupled to the individual electrode and the common electrode, and provided to apply a voltage for driving the piezoelectric body to the piezoelectric body, and a heating resistor that is formed of the same material as any of the individual electrode, the common electrode, and the drive wiring, and provided to heat the liquid in the pressure chamber.