In an example, a print apparatus includes a printhead carriage to receive a printhead comprising a print agent ejection nozzle, a drop detector to acquire a signal indicative of variations in a parameter detected by the drop detector over a period of drop detection, a memory to hold a print agent ejection signature, and processing circuitry. The processing circuitry includes a convolution module to convolve the drop detector signal with the print agent ejection signature, and the processing circuitry is to determine, from an output of the convolution module, an indication of similarity between the drop detector signal and the print agent ejection signature.

A substrate processing method includes determining a first impact of an ink droplet ejected toward a substrate moving at a first speed, determining a second impact of an ink droplet ejected toward the substrate moving at a second speed, determining a reference ejection speed based on the first impact and the second impact, determining a plurality of third impacts of a plurality of ink droplets respectively ejected from a plurality of nozzles toward the substrate moving at a third speed, determining an ink ejection speed of each of the plurality of nozzles based on the first impact and the plurality of third impacts, and comparing the ink ejection speeds of the plurality of nozzles with the reference ejection speed and determining whether ink ejection performance of the plurality of nozzles is abnormal.

A liquid droplet forming device for stably forming and ejecting a liquid droplet of a dispersion liquid containing settling particles includes an ejection head that ejects a liquid droplet of a liquid containing settling particles, and a control unit. The control unit controls a behavior of the ejection head by supplying an electrical signal. The ejection head includes a liquid holding portion that holds the liquid, a film-like member that has an ejection hole for ejecting the liquid droplet and that forms a liquid chamber, which holds the liquid, together with the liquid holding portion, and vibration applying means for vibrating the film-like member based on the electrical signal. The electrical signal includes an ejection signal for forming the liquid droplet by vibrating the film-like member, a stirring signal for vibrating the film-like member and a micro-vibration signal.

The disclosure concerns a test apparatus comprising a drum (100) configured such that ink drops (200) deposited on the surface of the drum form a printed marking (210) on the surface of the drum. The test apparatus further comprises an ink removal unit (300) configured to remove ink from the surface of the drum. The drum is at least partially transmissive of light and a light source (800) is disposed inside the drum to controllably illuminate the drum.

Methods and systems are described herein for driving droplet ejection devices with multi-level waveforms. In one embodiment, a method for driving droplet ejection devices includes applying a multi-level waveform to the droplet ejection devices. The multi-level waveform includes a first section having at least one compensating edge and a second section having at least one drive pulse. The compensating edge has a compensating effect on systematic variation in droplet velocity or droplet mass across the droplet ejection devices. In another embodiment, the compensating edge has a compensating effect on cross-talk between the droplet ejection devices.

Examples associated with drop velocity aberrancy detection are disclosed. One example includes firing ink through nozzles of a print-head past sensors to identify drop velocities of the nozzles. A target drop velocity is selected based on the drop velocities of the nozzles. An aberrant nozzles is detected when a nozzle has a drop velocity that deviates from the target drop velocity by a selected threshold. The aberrant nozzle is deactivated, and a good nozzle that will travel over locations traversed by the aberrant nozzle is configured to print portions of a job that would have been printed by the aberrant nozzle.

An image-recording apparatus includes a cartridge including a first storage chamber, a tank including a second storage chamber, a recording portion, a detected portion, a detector, and a wall portion. Liquid supplied from the first storage chamber to the second storage chamber through an inlet port is supplied from the second storage chamber to the recording portion through an outlet port. The wall portion partitions an internal space of the second storage chamber into a first region including the liquid inlet port and a second region including the detected portion. The wall portion extends upward than the liquid inlet port and the detected portion and downward than the liquid inlet port and the detected portion. Communication between the first region and the second region is allowed through upper and lower communication portions. The upper communication portion is positioned upward than the liquid inlet port and the detected portion.

Methods and systems are described herein for driving droplet ejection devices with multi-level waveforms. In one embodiment, a method for driving droplet ejection devices includes applying a multi-level waveform to the droplet ejection devices. The multi-level waveform includes a first section having at least one compensating edge and a second section having at least one drive pulse. The compensating edge has a compensating effect on systematic variation in droplet velocity or droplet mass across the droplet ejection devices. In another embodiment, the compensating edge has a compensating effect on cross-talk between the droplet ejection devices.

A drop detector includes a printed circuit board (PCB) including a number of optical channels each formed by a light emitter and a light detector and a number of holes defined in the PCB over which the optical channels pass over and through which a number of ejected drops from a number of printheads pass through wherein each of the number of holes defined in PCB are sized to contour the shape of the number of the printheads.

A continuous ink jet print head (10), including: an ink droplet generator (116) configured to emit an ink droplet (158) along an undeflected droplet flight path (30); a charge electrode (118) configured to impart a charge to the ink droplet; deflector plates (120A, 120B) adjacent the undeflected droplet flight path, downstream from the charge electrode, and configured to deflect the ink droplet to a deflected droplet flight path that lies within a range of deflected flight paths bounded by at least deflected droplet flight path and a most deflected droplet flight path; a gutter (122) configured to receive an ink droplet traveling along the undeflected droplet flight path; and an ink buildup sensor (102) configured to detect an accumulation of ink (140) relative to a droplet flight path disposed within the range of deflected flight paths.