Adc (Analog-To-Digital Converter); Thermal Printhead - HP PageWriter XL M1705B Service Manual

ADC (Analog-to-Digital
This is an 8-bit parallel A/D converter used to measure printhead
Converter)
temperature, battery voltage, and motor supply voltage.
Thermal Printhead
The thermal printhead is a line of 1728 printing elements. Each
printing element is a resistive heater. Heat from these elements
blackens the thermoreactive paper, creating an image. A 1728-bit
shift register (on the printhead) contains the dot data for the print
line. Data is serially loaded into the shift register, then latched so
that data for the next line may be shifted into the head while the
present line prints. A strobe signal enables printing. The pulse width
of the strobe is adjusted to compensate for different recording speeds
and variations in supply voltage, average heater resistance, and
temperature, which is sensed by a thermistor on the printhead heat
sink.
. -
I n
PRINTER
RAU
Figure 5-11. Printer Block Diagram.
Theory of Operation 5-23