HP 750c Service Manual - Page 47

Cartridges A line sensor on the carriage PCA provides the servo processor with information used to align the cartridges. It also provides a media edgeĆsensing capability to the plotter (for width measurement). The carriage ASIC controls the firing of the cartridges. It receives pixel data from the processorĆsupport ASIC over a synchronous serial channel. The carriage ASIC contains: D A 2 x 208Ćbit shift register (one bit per cartridge nozzle), which performs a serialĆtoĆparallel conversion on the data. D Timing and sequencing circuitry to ensure that cartridge nozzles are fired in the correct sequence and at the correct time. D Fire waveform generators to create the fireĆpulse waveforms used to fire the cartridges. D Circuitry for controlling the temperature of the cartridge while printing (brilliant pulse warming). Cartridge drivers provide the power necessary to fire the cartridges under the control of the carriage ASIC. During cartridge testing, when the carriage is docked in the service station, the processorĆ support ASIC provides a means to generate a fire position pulse. The carriage ASIC will receive this signal and fire selected nozzles. If a drop is sensed by the drop detector each time a nozzle is fired, the nozzle is working properly. The independently generated fire position pulse is also used for firing to clear clogged nozzles. WarmĆup pulses are generated when in the WarmĆup When Idle" mode. Mechanical Overview CarriageĆAxis Mechanism The carriage (YĆaxis) motor is mounted under the plotter's right endcover. It is electrically connected to the main PCA, which contains a carriageĆmotor driver. Its drive shaft is mechanically connected to the carriage via a drive belt. When the carriage motor rotates, it moves the carriage assembly. An optical encoder, located on the carriage assembly, provides positional feedback for carriage servo control. Line Sensor The line sensor on the cartridge carriage is used to: D Detect and measure lines when performing cartridge alignment and accuracy calibration. D Detect media width and skew during media loading. D Calibrate the mediaĆaxis (for banding reduction) using a mark on the roller. C4705-90000 Functional Overview 5-5