HP 750 - Manual (Page 47)

Functional Overview C4705-90000 5-5
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.