Abstract: In certain examples, a printing device comprises a print head, a dryer, a heat exchanger, a distribution system and a controller. The heat exchanger is coupled to an exhaust of the dryer to produce pre-heated air. The distribution system is coupled to the heat exchanger and a plurality of regions of the printing device. The controller causes the distribution system to distribute the pre-heated air from the heat exchanger among the plurality of regions based on an operating parameter of the printing device.

Abstract: There is disclosed a non-transitory machine-readable medium encoded with instructions executable by a processor and comprising instructions to: control print apparatus to print a test pattern 11 on a test region of a print medium 4; receive test data relating to the test pattern 11 printed on the print medium 4 from a sensor 8; analyse the test data with reference to baseline data to determine if the test pattern 11 satisfies a print quality criterion; output an instruction to operate the print apparatus in a first mode, in which a pre-printing treatment is not applied to the print medium, in response to determining that the test pattern 11 satisfies the print quality criterion, the pre-printing treatment comprising wiping a printing surface of the print medium with a wiper element 10, 20; and output an instruction to operate the print apparatus in a second mode, in which the pre-printing treatment is applied to the print medium 4, in response to determining that the test pattern 11 satisfies the print qualit

Abstract: Circuits for controlling an impeller in a fluid flow distribution system to achieve a target fluid flow are disclosed. The circuit to output a signal representative of a speed value (NT) of the impeller derived from a stored power consumption value (Wi) and speed value (Ni) pairs to achieve the target fluid flow. The circuit to receive a power signal representative of an input power consumption value (W) of the impeller at the speed value (NT) to input fluid to the fluid flow distribution system and to compare the value (W) represented by a power signal for the speed value (NT) with the stored value (Wi) and impeller speed value (Ni) pairs to determine a least difference impeller speed value (NL) of the stored pair comprising a least difference between the value (W) and the value (Wi). The circuit to output a speed signal representative of value (NL).

Abstract: A printing system comprises a processor to obtain image data comprising first image data defining a first color plane of the image and comprising second image data defining a second color plane of the image. The processor is to manipulate the image data such that the second color plane is shifted relative to the first color plane in a media axis direction of a printer. The printing system comprises a printer to print the manipulated image data with the printer.

Abstract: A device (2) includes a media roll (4) to output a print medium (M) in a forward direction (26) and a wiper roll (6) to contact the surface of the print medium (M) at a rotation speed to cause friction on the print medium (M). The device (2) may determine a radius (r2) of the media roll (4) outputting the print medium (M) and, based on this radius (r2), adapt parameters such as the rotation speed of the wiper roll and a back tension (T2) exerted by the media roll (4) on the print medium (M) so as to control the friction caused by the wiper roll (6) on the print medium (M).

Abstract: A printer includes a print head to print by ejecting drops of a printing fluid;, a memory to store a correction measure, the correction measure to modify printing a pattern to compensate for decel, and a processor. The processor analyzes print data for a pattern that, when printed using the print head, triggers decel, controls the print head to eject drops of the printing fluid in accordance with the print data, when the analysis indicates that the pattern to be printed triggers decel, applies the correction measure upon printing the pattern, and, when the analysis indicates that the pattern to be printed does not trigger decel, does not apply the correction measure upon printing the pattern.

Abstract: A printer includes a print head to print a pixel by ejecting drops of a printing fluid from the print head, and a controller. The controller monitors a drop volume of the printing fluid ejected by the print head. When the drop volume is below a threshold, the controller controls the print head in accordance with a first print mode to increase the frequency of ejecting drops of the printing fluid within the pixel print time with a decrease in the drop volume that maintains a print quality parameter. The controller changes to a second print mode to increase the pixel print time that maintains the print quality parameter.

Abstract: Example implementations relate to color compensation. Some examples may print a calibration target background on a non-opaque media. The calibration target background may have a color that increases a dynamic range of a set of color measurements of a calibration target foreground. Some examples may print the calibration target foreground over the calibration target background. Additionally, some examples may measure an optical density of the calibration target foreground with a reflective sensor and may calibrate a printer based on the measured optical density.

Abstract: There is disclosed a non-transitory machine-readable medium encoded with instructions executable by a processor and comprising instructions to: control print apparatus to print a test pattern 11 on a test region of a print medium 4; receive test data relating to the test pattern 11 printed on the print medium 4 from a sensor 8; analyse the test data with reference to baseline data to determine if the test pattern 11 satisfies a print quality criterion; output an instruction to operate the print apparatus in a first mode, in which a pre-printing treatment is not applied to the print medium, in response to determining that the test pattern 11 satisfies the print quality criterion, the pre-printing treatment comprising wiping a printing surface of the print medium with a wiper element 10, 20; and output an instruction to operate the print apparatus in a second mode, in which the pre-printing treatment is applied to the print medium 4, in response to determining that the test pattern 11 satisfies the print qualit

Abstract: In one example, a vapor control heater for a printer includes a housing, a heating element at least partially enclosed by the housing, and a fan to move air over the heating element and into a flow of air from the printer dryer.

Abstract: A device (2) includes a media roll (4) to output a print medium (M) in a forward direction (26) and a wiper roll (6) to contact the surface of the print medium (M) at a rotation speed to cause friction on the print medium (M). The device (2) may determine a radius (r2) of the media roll (4) outputting the print medium (M) and, based on this radius (r2), adapt parameters such as the rotation speed of the wiper roll and a back tension (T2) exerted by the media roll (4) on the print medium (M) so as to control the friction caused by the wiper roll (6) on the print medium (M).

Abstract: A method of printing a pattern from at least two rows of fluid ejection nozzles, said nozzles ejecting a first fluid in a multi-pass printing mode, the method comprising: dividing the pattern to be printed between the rows of fluid ejection nozzles; applying masks to the rows of fluid ejection nozzles for printing with selected nozzles of each of the rows of fluid ejection nozzles during each pass; wherein a first mask for printing from a first row of fluid ejection nozzles during an n-th pass is different from a second mask for printing from a second row of fluid ejection nozzles during said n-th pass.

Abstract: In certain examples, a printing device comprises a print head, a dryer, a heat exchanger, a distribution system and a controller. The heat exchanger is coupled to an exhaust of the dryer to produce pre-heated air. The distribution system is coupled to the heat exchanger and a plurality of regions of the printing device. The controller causes the distribution system to distribute the pre-heated air from the heat exchanger among the plurality of regions based on an operating parameter of the printing device.

Abstract: 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.

Abstract: An example method for determining an amount of a translucent printing fluid in accordance with the present disclosure is provided. The example method comprises printing a plurality of test patterns with different proportions of colored and translucent printing fluids. The plurality of test patterns comprise a first area and a second area contiguous with the first area, wherein a color of the second area is different from a color of the first area. Migration characteristics of the plurality of test patterns are analyzed to determine an amount of translucent printing fluid to use for a successive printing operation.

Abstract: A method is described in which a first color is detected at a user-selected arbitrary position of a first print; a second color is detected at a user-selected arbitrary position of a second print printed by a printer; a color difference between the first color and the second color is determined; and settings of the printer are changed to reduce the color difference in further prints printed by the printer.

Abstract: Provided in one example is a printing system. The system includes a printing zone including a platen (50). The system includes a drive to move a medium (58) through the printing zone. The system includes a suction force generator (78) to generate a suction force to hold down the medium onto the platen while the drive moves the medium through the printing zone. The system includes a sensor (52) to monitor the movement of the medium through the printing zone in a medium advance direction. The system includes a controller to determine that the suction force generated by the suction source generator is insufficient based on an output of the sensor.

Abstract: Herein is described a method involving a drop detector. The method may comprise: ejecting ink drops from the nozzles on a printhead toward a drop detector. A drop characteristic may then be determined from the drop detector for each ink-jet nozzle. Drop characteristics for the nozzles across the printhead may be collated into a data set, and compared with a predetermined data set for a printhead having predetermined print behaviour to determine if and how the data sets differ in terms of the pattern of drop characteristics across the printheads. If the data sets differ, a recovery strategy may be selected based how the data sets differ in terms of the pattern of drop characteristics across the printheads. A system and computer readable medium are also described herein.

Abstract: In some examples, a method includes, in response to a fluid firing unit being operated according to a normal printing mode, applying a first voltage to the fluid firing unit to fire the fluid firing unit during a printing operation. The method further includes determining, using a sensor, whether a predetermined condition is met, and in response to determining that the predetermined condition is met, operating the fluid firing unit according to a recovery mode in which a second voltage higher than the first voltage is applied to the fluid firing unit to clean the fluid firing unit.

Abstract: A cleaning module includes an actuator device, a fluid chamber, and a wiper member. The actuator device may enter an activation state based on a movement of at least a portion of the actuator device in response to an engagement with the printhead. The fluid chamber may store and supply fluid to the porous wipe material in response to the activation state of the actuator device. The wiper member may apply pressure to a porous wipe material including the fluid therein to wipe the printhead.