A liquid discharge device including a drive circuit substrate that drives a piezoelectric element of a liquid discharge head, and that includes a substrate which includes a first wiring layer having a first wiring through which the first drive signal propagates, a second wiring layer having a second wiring through which the second drive signal propagates, and a third wiring layer located between the first wiring layer and the second wiring layer and having a fourth wiring through which the reference voltage signal propagates, in which a third wiring through which the third drive signal propagates is provided on any one of the first wiring layer, the second wiring layer, and the third wiring layer.

A liquid discharge device including a first piezoelectric element that has a first electrode and a second electrode and discharges a liquid from a first nozzle by being driven, a second piezoelectric element that has a third electrode and a fourth electrode and discharges a liquid from a second nozzle by being driven, a reference voltage signal propagation path that electrically couples the second electrode and the fourth electrode and propagates the reference voltage signal supplied to a first coupling point to the second electrode and the fourth electrode, and a first capacitor electrically coupled to the reference voltage signal propagation path at a second coupling point provided in the reference voltage signal propagation path, in which the second coupling point is located between the first coupling point and the second electrode in the reference voltage signal propagation path.

In a liquid discharge apparatus, a head unit includes a plurality of print heads, and a housing that houses the print heads, in which a first print head in the plurality of print heads includes a substrate that includes a first side, a second side, a first surface, and a second surface, a first nozzle plate, a first integrated circuit that is provided on the first surface, that outputs an abnormality signal indicating presence or absence of abnormality of the first print head, a first flexible wiring substrate that is electrically coupled to the substrate, and a second integrated circuit that is provided on the first flexible wiring substrate, the second integrated circuit is located between the first nozzle plate and the substrate, and the substrate is provided so that the first surface faces downward and the second surface faces upward in a direction along a vertical direction.

A liquid discharge device includes: a piezoelectric element to which a drive voltage is applied; a nozzle from which a liquid is to be discharged in accordance with a change of the drive voltage; and circuitry configured to: generate: a first drive waveform including first multiple pulses switchable at first switch timings; and a second drive waveform including second multiple pulses different from the first multiple pulses switchable at second switch timings, at least one the first switch timings of the first multiple pulses of the first drive waveform and at least one of the second switch timings of the second multiple pulses of the second drive waveform are the same; select first selected pulses from the first multiple pulses in the first drive waveform; and select second selected pulses from the second multiple pulses in the second drive waveform.

A liquid discharge device including a first drive circuit, a second drive circuit, a third drive circuit, a fourth drive circuit, a connector coupled to a discharge head, and a substrate that includes a first wiring which couples the connector and the first drive circuit outputting a first drive signal, a second wiring which couples the connector and the second drive circuit outputting a second drive signal, a third wiring which couples the connector and the third drive circuit outputting a third drive signal, and a fourth wiring which couples the connector and the fourth drive circuit outputting a fourth drive signal, in which the first wiring is shorter than the second wiring, the third wiring, and the fourth wiring, and the fourth wiring is longer than the first wiring, the second wiring, and the third wiring.

A liquid ejecting apparatus is configured to drive a driving element in accordance with a driving signal applied by control of the controller. A driving signal includes a first ejection pulse for ejecting liquid, a second ejection pulse for ejecting liquid, and a non-ejection pulse for not ejecting liquid. The controller selects the first ejection pulse and the second ejection pulse to supply to the driving element, when a first amount of liquid is to be ejected from the nozzle in the unit period. The controller selects the non-ejection pulse and the second ejection pulse to supply to the driving element, when a second amount of liquid that is smaller than the first amount of liquid is to be ejected from the nozzle in the unit period. The second amount of liquid is larger than an amount of liquid ejected by only the second ejection pulse.

A liquid discharge device includes a first discharge portion, a second discharge portion, a first drive circuit outputs a first drive signal that the first discharge portion discharges a liquid having a first discharge amount, a second drive circuit outputs a second drive signal that the first discharge portion does not discharge a liquid, a third drive circuit outputs a third drive signal that the second discharge portion discharges a liquid having a second discharge amount, and a fourth drive circuit outputs a fourth drive signal that the second discharge portion does not discharge the liquid, in which the third drive circuit is located between the first drive circuit and the second drive circuit along the one direction, and a shortest distance between the fourth drive circuit and the second drive circuit is shorter than a shortest distance between the fourth drive circuit and the third drive circuit.

A liquid discharge device including a substrate that includes a first through-hole, a first drive circuit, a second drive circuit, a third drive circuit, a metal frame, and a first screw that is inserted through the first through-hole and attaches the metal frame to the substrate, in which the first drive circuit outputs a first drive signal, the second drive circuit outputs a second drive signal, the third drive circuit outputs a third drive signal, the first drive circuit, the second drive circuit, and the third drive circuit are located side by side in an order of the first drive circuit, the second drive circuit, and the third drive circuit on the substrate along one direction, and the first through-hole is located between the first drive circuit and the second drive circuit in the one direction.

A liquid droplet discharging apparatus includes: a discharging head having: a liquid channel including a nozzle; and an energy applying part which applies, to liquid inside the liquid channel, discharge energy for discharging a liquid droplet from the nozzle; a signal outputting circuit which outputs signals depending on whether the nozzle satisfies a predetermined discharging performance; and a controller. The controller determines whether the nozzle satisfies the predetermined discharging performance, and estimates viscosity of the liquid inside the discharging head based on: viscosity estimation data in which discharge energy information and viscosity information are associated with each other, and a result of the determination performed in a case that the controller controls the energy applying part based on the discharge energy information and that the discharge energy is thereby applied to the liquid inside the liquid channel.

A head unit includes a plurality of ejection portions that include a first ejection portion and a second ejection portion, a determination portion that determines a liquid ejection state of the first ejection portion and determines a liquid ejection state of the second ejection portion, and a storage portion that includes a first storage region storing first determination information indicating a determination result for the first ejection portion from the determination portion, and a second storage region storing second determination information indicating a determination result for the second ejection portion from the determination portion.