Abstract: In some examples, a printhead die includes a nozzle to be fired by a fire pulse, and a sensor to measure, during a firing of the nozzle by the fire pulse, a measured signal comprising an impedance characteristic of a fluid sample of the nozzle, in response to an input signal applied to the fluid sample. A comparator is to compare the measured signal to a reference value, and a counter is to count over an evaluation interval in response to the comparing indicating that an evaluation criterion is satisfied, and the counter is to stop counting in response to the comparing indicating that the evaluation criterion is not satisfied, a count value of the counter providing an indicator of nozzle chamber operation corresponding to the measured signal.

Abstract: According to an example, a printing system may include a drop ejecting element and a fluid circulating element corresponding to the drop ejecting element. The printing system may also include a logic device that is to receive a data stream addressed to the drop ejecting element, determine whether the data stream indicates that the drop ejecting element is to be energized, and in response to a determination that the data stream does not indicate that the drop ejecting element is to be energized, energize the fluid circulating element.

Abstract: An example device in accordance with an aspect of the present disclosure includes modules to generate an input signal, apply the input signal to an ink sample to obtain an ink signal, compare the ink signal to a reference value, and identify whether the ink signal is consistent with an ink signature. A module may be contained on an inkjet printhead die.

Abstract: An example device in accordance with an aspect of the present disclosure includes modules to generate an input signal, apply the input signal to an ink sample to obtain an ink signal, compare the ink signal to a reference value, and identify whether the ink signal is consistent with an ink signature. A module may be contained on an inkjet printhead die.

Abstract: In some examples, a print head comprises a plurality of nozzles comprising respective heaters on the print head, each heater of the heaters to be driven by a respective firing pulse to form a bubble in a corresponding nozzle. The print head further comprises a first time repository on the print head to store a first time instant, and a second time repository on the print head to store a second time instant, and a plurality of detect circuits provided onto the print head and coupled to corresponding nozzles of the plurality of nozzles, wherein each respective detect circuit of the plurality of detect circuits is to detect a change in respective impedances for a respective nozzle at the first time instant and the second time instant.

Abstract: In some examples, a printhead die includes a nozzle to be fired by a fire pulse, and a sensor to measure, during a firing of the nozzle by the fire pulse, a measured signal comprising an impedance characteristic of a fluid sample of the nozzle, in response to an input signal applied to the fluid sample. A comparator is to compare the measured signal to a reference value, and a counter is to count over an evaluation interval in response to the comparing indicating that an evaluation criterion is satisfied, and the counter is to stop counting in response to the comparing indicating that the evaluation criterion is not satisfied, a count value of the counter providing an indicator of nozzle chamber operation corresponding to the measured signal.

Abstract: Measuring an inkjet nozzle may include taking at least one impedance measurement after the firing command is sent to detect the presence of a drive bubble and taking another impedance measurement to detect a collapse of the drive bubble.

Abstract: The present subject matter relates to evaluating print head nozzle condition of a plurality of nozzle columns. Each of the plurality of nozzle columns comprises a set of nozzles. A plurality of drive bubble detect modules are activated, by a timing circuit coupled to each of the plurality of nozzle columns upon occurrence of at least a first predetermined time instant and a second predetermined time instant. For each of the plurality of nozzle columns, test results for a nozzle of the nozzle column are registered by the corresponding drive bubble detect module. Test results obtained based on impedances measured across a nozzle associated with the nozzle column corresponding to a drive bubble detect module are registered by the drive bubble detect module at the first predetermined time instant and the second predetermined time instant. The print head nozzle condition of the nozzle is evaluated based on the test results.

Abstract: Measuring an inkjet nozzle may include taking at least one impedance measurement after the firing command is sent to detect the presence of a drive bubble and taking another impedance measurement to detect a collapse of the drive bubble.

Abstract: An example device in accordance with an aspect of the present disclosure includes modules to communicate an input signal to an ink sample to obtain an ink signal, compare the ink signal to a reference value, and identify an indicator of nozzle chamber operation corresponding to the ink signal. A module may be contained on an inkjet printhead die, such that the device may generate the input signal on the inkjet printhead die.

Abstract: A fluid ejection device includes a plurality of analog devices, and a storage element storing an authentication value based on electrical characteristics of a subset of the plurality of analog devices.

Abstract: In one example, a device for driving a nozzle of a fluid-jet printing device includes a circuit to, for each pixel time of a plurality of pixel times select a waveform from a plurality of waveforms based on more than one of waveform time delay, waveform pulse width and waveform shape, and apply the selected waveform to the nozzle to drive the nozzle to eject fluid for a current pixel time.

Abstract: In an example, a method of managing a nozzle condition test on a printhead includes instructing a printhead to perform impedance measurements on a plurality of nozzles in a first set of nozzles. The method also includes retrieving from the printhead, an impedance measurement result corresponding with each nozzle, where each impedance measurement result indicates a nozzle condition of its corresponding nozzle.

Abstract: A fluid ejection device includes a plurality of analog devices, and a storage element storing an authentication value including a plurality of bits, a first bit of the plurality of bits based on measured electrical characteristics of a first subset of the analog devices, and a second bit of the plurality of bits based on measured electrical characteristics of a second subset of the analog devices, the second subset different from the first subset.

Abstract: In some examples, a print head includes a plurality of nozzles, a test result register to store a drive bubble detect (DBD) test result for a first nozzle of the plurality of nozzles, and a result-ready register to store a status indication set to a predetermined value provided responsive to storing of the DBD test result in the test result register, where the test result register and the result-ready register are accessible by a control unit outside the print head to evaluate a nozzle condition based on the DBD test result in the test result register.

Abstract: In an example, a print head comprises a nozzle to be activated by a delayed fire pulse that is delayed from an initial fire pulse, a sensor to measure an impedance of the nozzle, and a detector to determine a first time instant following the delayed fire pulse for registering a first impedance measurement by the sensor.

Abstract: Printheads and techniques for manufacturing printheads are disclosed. An example method includes forming drive circuit components in a circuit layer. The method also includes forming a fluidic device that causes fluid to be ejected from a nozzle. The method also includes forming an interconnect layer that couples the drive circuit components.

Abstract: A method of operating a printing device during a power loss event includes, with a power loss detection device, detecting an power loss to a number of high voltage devices. The method further includes, with a voltage regulator coupled to printhead fire control circuitry, maintaining a power loss protection supply voltage (VDD_plp) to the printhead fire control circuitry.

Abstract: A method of operating a printing device during a power loss event includes, with a power loss protection supply voltage generator coupled to a printhead driving circuit, maintaining a power loss protection supply voltage (VDD—plp) to the printhead driving circuit until a high voltage power supply (VPP) to the high voltage devices drops below a threshold voltage.

Abstract: In an example, a method for determining an issue in an inkjet nozzle includes providing an initial fire pulse for firing a nozzle, and receiving the initial fire pulse as a delayed fire pulse at a primitive of the nozzle. The method includes firing the nozzle with the delayed fire pulse, and determining a first time instant following the delayed fire pulse for taking a first impedance measurement across the nozzle.