The present invention addresses the problem of enabling a charge control-type inkjet printer to enable real-time control during an operation and to maintain optimal printing conditions while operating. This charge control-type inkjet printer is provided with: a printing head including a nozzle unit for discharging ink; a pressure reduction valve for adjusting the pressure of the ink to be supplied to the nozzle unit of the printing head; and an ink container for accommodating the ink to be supplied to the nozzle unit of the printing head, wherein an imaging unit is further provided which images an image of ink that is discharged from the nozzle unit and is in a particulate state.

The present invention addresses the problem of enabling a charge control-type inkjet printer to enable real-time control during an operation and to maintain optimal printing conditions while operating. This charge control-type inkjet printer is provided with: a printing head including a nozzle unit for discharging ink; a pressure reduction valve for adjusting the pressure of the ink to be supplied to the nozzle unit of the printing head; and an ink container for accommodating the ink to be supplied to the nozzle unit of the printing head, wherein an imaging unit is further provided which images an image of ink that is discharged from the nozzle unit and is in a particulate state.

A head unit includes a piezoelectric element displaced according to a driving signal to cause a liquid to be ejected, a driving signal generation unit that generates the driving signal, a residual vibration signal generation circuit that outputs a change in an electromotive force of the piezoelectric element according to residual vibration, in a pressure chamber in communication with a nozzle, that occurs after supply of the driving signal, as a residual vibration signal, an analog differential residual vibration signal generation circuit that converts the residual vibration signal into an analog differential residual vibration signal, a demodulation circuit that demodulates the analog differential residual vibration signal and outputs a demodulated signal, an AD converter that converts the demodulated signal into a digital signal, and a determination unit that determines, based on the digital signal, a state in the pressure chamber.

A head unit includes a piezoelectric element displaced according to a driving signal to cause a liquid to be ejected, a driving signal generation unit that generates the driving signal, a residual vibration signal generation circuit that outputs a change in an electromotive force of the piezoelectric element according to residual vibration, in a pressure chamber in communication with a nozzle, that occurs after supply of the driving signal, as a residual vibration signal, an analog differential residual vibration signal generation circuit that converts the residual vibration signal into an analog differential residual vibration signal, a demodulation circuit that demodulates the analog differential residual vibration signal and outputs a demodulated signal, an AD converter that converts the demodulated signal into a digital signal, and a determination unit that determines, based on the digital signal, a state in the pressure chamber.

A method for controlling a liquid ejecting apparatus includes: driving a ejecting section by using each of a plurality of candidate waveforms of a minute vibration pulses in parallel with movement of a liquid ejecting head, the minute vibration pulses vibrates a liquid surface within a nozzle of the liquid ejecting head without causing liquid to be ejected from the nozzle, the candidate waveforms are different from each other; and setting a waveform of the minute vibration pulses included in a driving signal generated by the signal generating section, in accordance with an instruction accepted with an operating device.

A liquid ejecting apparatus includes a flow path member including a common liquid chamber communicating with each of a plurality of nozzles formed in a nozzle surface, via a corresponding pressure generating chamber, a supply port provided in an inner wall of the common liquid chamber to supply a liquid to the common liquid chamber, a discharge port provided in a ceiling of the common liquid chamber to discharge an air bubble from the common liquid chamber, and a wall continuously extending from the inner wall, and including a surface opposing the discharge port.

A liquid ejecting apparatus includes a flow path member including a common liquid chamber communicating with each of a plurality of nozzles formed in a nozzle surface, via a corresponding pressure generating chamber, a supply port provided in an inner wall of the common liquid chamber to supply a liquid to the common liquid chamber, a discharge port provided in a ceiling of the common liquid chamber to discharge an air bubble from the common liquid chamber, and a wall continuously extending from the inner wall, and including a surface opposing the discharge port.

The inkjet recording apparatus includes a recording head, a cap member, a humidifying part for humidifying interior of the cap member, a cap moving mechanism, a controller, and a storage part. The storage part has stored a non-capping period table in which a number of vibrations of ink level within each nozzle is increased based on a non-capping period of an ink ejection surface, and a capping period table in which the number of vibrations is decreased based on a capping period of the ink ejection surface. In response to respective lengths of the non-capping period and the capping period from an end of ink ejection until a start of next ink ejection, the controller sets the number of vibrations at a start time of next ink ejection by using the non-capping period table and the capping period table.

The inkjet recording apparatus includes a recording head, a cap member, a humidifying part for humidifying interior of the cap member, a cap moving mechanism, a controller, and a storage part. The storage part has stored a non-capping period table in which a number of vibrations of ink level within each nozzle is increased based on a non-capping period of an ink ejection surface, and a capping period table in which the number of vibrations is decreased based on a capping period of the ink ejection surface. In response to respective lengths of the non-capping period and the capping period from an end of ink ejection until a start of next ink ejection, the controller sets the number of vibrations at a start time of next ink ejection by using the non-capping period table and the capping period table.

A method for testing at least one nozzle of a multi-jet print head of an inkjet printer including a plurality of nozzles (4), at least one 1.sup.st and one 2.sup.nd deviation electrode (14a, 14b) for each jet, method in which: at least one jet is formed using the nozzle (9), at a drop formation frequency, an estimate is made of:

a cutoff frequency (Fc) of at least this jet, by variation of the jet formation frequency, at a constant jet velocity, or, at constant formation frequency of the drops from at least this jet, by variation of the jet velocity, the velocity at which the cutoff frequency (Fc) is equal to the formation frequency; this cutoff frequency (Fc) or this velocity is compared with a reference value and the functional or non-functional state of at least the nozzle is deduced.