A printhead may include a nozzle, a firing chamber fluidly coupled to the nozzle, a printing fluid slot fluidly coupled to the firing chamber, and a sensor to detect a plurality of complex impedance values of a printing fluid at the printhead over a plurality of frequencies and create a printing fluid signature of the printing fluid. A method of determining at least one characteristic of a printing fluid provided to a printhead ma include, with a number of sensors, applying an alternating current at a plurality of frequencies over time to the printing fluid to receive a plurality of complex impedance values and comparing the plurality of complex impedance signals to a number of stored signals.

A fluid ejection system includes a fluid ejection die, a service station assembly, and a controller. The fluid ejection die includes at least one strain gauge sensor to sense strain. The service station assembly is to service the fluid ejection die. The controller is to receive the sensed strain from the at least one strain gauge sensor during servicing of the fluid ejection die and adjust or stop servicing of the fluid ejection die in response to the sensed strain exceeding a servicing threshold.

A fluid ejection die includes a plurality of actuation devices to eject fluid drops, at least one strain gauge sensor to sense strain, and a comparator. The comparator is to provide a fault signal in response to the sensed strain exceeding an impact threshold.

A fluid ejection die includes a plurality of actuation devices to eject fluid drops, at least one strain gauge sensor to sense strain, and a comparator. The comparator is to provide a fault signal in response to the sensed strain exceeding an impact threshold.

A system comprises a printhead including a nozzle, a temperature sensor and a processor. The temperature sensor detects the temperature of a location of a print surface upon firing the nozzle to eject a drop of printing fluid to the location of the print surface. The processor determines whether the nozzle ejected the drop properly using the detected temperature.

A system comprises a printhead including a nozzle, a temperature sensor and a processor. The temperature sensor detects the temperature of a location of a print surface upon firing the nozzle to eject a drop of printing fluid to the location of the print surface. The processor determines whether the nozzle ejected the drop properly using the detected temperature.

A printer includes at least a first printhead and a second printhead, each of which is operatively connected to a source of aqueous ink having a color that is different than the color of aqueous ink connected to the other printhead. A first source of infrared (IR) radiation is positioned between the first and second printheads and a second source of IR radiation follows the first and second printheads. The first source of IR radiation is tuned to heat color pigment particles in the aqueous ink connected to the first printhead only and the second source of IR radiation is tuned to heat color pigment particles in the aqueous ink connected to the second printhead only.

A printer includes at least a first printhead and a second printhead, each of which is operatively connected to a source of aqueous ink having a color that is different than the color of aqueous ink connected to the other printhead. A first source of infrared (IR) radiation is positioned between the first and second printheads and a second source of IR radiation follows the first and second printheads. The first source of IR radiation is tuned to heat color pigment particles in the aqueous ink connected to the first printhead only and the second source of IR radiation is tuned to heat color pigment particles in the aqueous ink connected to the second printhead only.

An image forming apparatus includes (a) recording heads, (b) an optical detection part that emits light, receives reflected light reflected on a recording medium, and generates a sensor output in correspondence with the reflected light, (c) a medium information acquisition processing part that sets a pattern image formation position where a test pattern image is formed on the recording medium based on reflection characteristics, the reflection characteristics being obtained from the sensor output of the optical detection part, (d) a pattern image formation processing part that forms the test pattern image at the pattern image formation position using the recording heads, (e) a pattern image detection processing part that detects the test pattern image at the pattern image formation position using the optical detection part, generating a detection result, and (f) an image forming condition setting part that sets an image forming condition based on the detection result.

An image forming apparatus includes (a) recording heads, (b) an optical detection part that emits light, receives reflected light reflected on a recording medium, and generates a sensor output in correspondence with the reflected light, (c) a medium information acquisition processing part that sets a pattern image formation position where a test pattern image is formed on the recording medium based on reflection characteristics, the reflection characteristics being obtained from the sensor output of the optical detection part, (d) a pattern image formation processing part that forms the test pattern image at the pattern image formation position using the recording heads, (e) a pattern image detection processing part that detects the test pattern image at the pattern image formation position using the optical detection part, generating a detection result, and (f) an image forming condition setting part that sets an image forming condition based on the detection result.