3600 Printer Maintenance Manual
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.
