Genicom 3600 - Manual (Page 172)

3600 Printer Maintenance Manual
A-18
Font Caching
Most of the imaging time during text creation is spent converting character
description data into character images. The remainder of the time is used to
copy the character images into image RAM. Font caching helps to eliminate the
reimaging of characters that have already been used.
With font caching, a character is imaged into the cache the first time it is
requested. It is then copied from the cache into the appropriate area of image
RAM. The next time that same character is needed, it only has to be copied
from the font cache. The illustration on the following page shows the process of
generating and caching a specified character.
When used with band buffering, even if there are no repeated characters in a
label, font caching may still enhance imaging. If a character is large or is
positioned near a band boundary, portions of its image may fall into multiple
bands. The character’s image will be referenced repeatedly as each of the bands
is imaged. As before, if the character is cached, it will only need to be imaged a
single time.
Print Energy Compensation
The digital thermal compensation system and the global compensation system
combine to provide the printer with maximum printhead energy control to
optimize print quality.
Digital Thermal Compensation
Each dot on the printhead has its own history RAM. This RAM contains a dot’s
previous burn history, what the current burn will be, and what adjacent dots
are doing. This data, along with the media sensitivity information, is used to
determine the proper amount of energy for that dot.
For example, if the dot history showed that the dot had been turned on most of
the time, this profile would indicate that the energy built up in the dot area was
sufficient enough for the task and the dot would be turned off for a period of
time. Using this method provides for a specific amount of energy for the task
that dot is performing.
Global Compensation
Global compensation is the energy management to the printhead that affects all
of the dots on the printhead. External inputs to this system are the darkness
adjust control and the online darkness command. Other inputs include the
ambient temperature, the printhead resistance, and printhead temperature.