Hewlett-packard Development Company, L.p.

Hfwi Ftt-packard Development Company, L.p.

Jordi Bas

Alejandro Mielgo

Francisco Gomez

Jose Francisco Bravo De Vega

Oscar Moya Rojo

Albert Serra

David Peinado

Laura Portela

With the purpose of providing an improved cleaning mechanism that accomplishes better results and that may be used in thermal and piezoelectric printing, it is dis-closed a method for cleaning a printhead comprising: moving a wiper along a plurality of nozzles of the printhead; and pressurizing the nozzles within the printhead, the pressurization of each nozzle causing ink to be expelled in an expelling direction; wherein a controller is to detect the position of the wiper and to selectively pressurize at least some of the nozzles for which the position of the wiper corresponds to its expelling direction.

Printhead cleaning methods

A printing device comprises a droplet generator for generating a droplet of printing fluid, a droplet detector for detecting a generated droplet of printing fluid, and a controller. The droplet detector is moveable along an axis. The controller is to cause the droplet detector to be positioned at a known location along the axis, cause the droplet generator to generate a droplet, receive a measurement signal from the droplet detector, and determine a location of the droplet generator based on the received measurement signal and the known location.

Printer calibration techniques

Apparatus to detect droplets and methods for detecting droplets are described. The apparatus comprise a light emitter and a light detector. The light emitter is to emit light along an optical axis, the light having a spatial intensity distribution profile with a peak that is non-coincident with the optical axis. The light detector is located relative to the light emitter such that, in use, the peak of the spatial intensity distribution profile is incident on the light detector.

Droplet detection

In some examples, a printhead drop detector comprises a plurality of drop detection units. Each drop detection unit may comprise a radiation source and radiation detector and may be to detect a drop passing through a sampling volume between the radiation source and the radiation detector. A radiation detector of a first drop detection unit and a radiation source of a second drop detection unit is arranged on a first side of the sampling volume; and a radiation source of the first drop detection unit and a radiation detector of the second drop detection unit is arranged on the second side of the sampling volume.

Printhead drop detectors

In an example, a print apparatus may include a print head assembly and a maintenance cartridge. An example maintenance cartridge may include a wiper system. An example wiper system may include a web wipe and a plurality of independently biased members adjacent each other with respect to a width of the web wipe. Another example wiper system may include a plurality of bias members, a plurality of carriers coupled to the plurality of bias members, and a plurality of rollers coupled to the plurality of carriers and located along a width of a wiping area.

Wiper with bias members

In some examples, a printhead drop detector comprises a plurality of drop detection units to detect any drops passing through a sampling volume between the radiation source and the radiation detector. A radiation detector of a first drop detection unit and a radiation source of a second drop detection unit is arranged on a first side of the sampling volume and a radiation source of the first drop detection unit and a radiation detector of the second drop detection unit is arranged on the second side of the sampling volume. The distance between the first drop detection unit and the second drop detection unit is based on an angle of a beam producible by the first radiation source such that the beam is wide enough to cross into a portion of the sampling volume corresponding with the second drop detection unit.

Beam angles of drop detectors

In one example in accordance with the present disclosure a drop detection device is described. The device includes an emitter member having a number of emitter cavities to relay a number of beams towards a number of detector cavities in a detector member. The device also includes a detector member that is spaced from the emitter member. The detector member includes a number of detector cavities to receive a number of beams from the number of emitter cavities. The device also includes a number of ribs coupled to both the emitter member and the detector member. The number of ribs space and align the emitter member and detector member and align the number of emitter cavities with the corresponding number of detector cavities.

Drop detection with ribs to align emitters and detectors

A printing apparatus may comprise a print head including nozzles to eject liquid drops, a drop sensor to detect flying liquid drops ejected by at least some of the nozzles, and a controller. The controller is to control at least some of the nozzles to sequentially eject liquid drops while the drop sensor is at a predetermined position relative to the nozzles, to determine the actual position of the drop sensor relative to the nozzles based on a sensor profile including a nozzle location specific signal characteristic of the sequentially ejected liquid drops detected by the drop sensor, and to calculate an offset between the determined actual position and the predetermined position. The controller may take the offset into account in positioning the drop sensor relative to one of the nozzles to detect a liquid drop ejected from that nozzle in a subsequent operation.

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Sant Cugat del Valles, Spain

Jordi Bas