CognitiveTPG A799II - Manual (Page 28)

Chapter 4: Using the Printer 28
A799II Two-Color Thermal Receipt Printer: User Guide A799-2UG0000 Rev. A 09/2013
Preventing overheating of the printhead
There are restrictions on the duty cycle because of the heat generated by the thermal printhead when printing solid blocks
(regardless of the length of the block in relation to the print line). The restrictions are ambient temperature, the percentage
of time (measured against one minute) of continuous solid printing, and the amount of coverage.
Keep in mind that the ambient temperature may be affected by factors such as direct exposure to sun or close proximity to
heating elements.
Caution: When the duty cycle exceeds the limits shown in the table, the receipt printhead will heat up and shut down. This
may damage the printhead.
To avoid this problem, do one or a combination of the following:
1
Reduce the amount of coverage.
2 Reduce the time of continuous solid printing.
3 Reduce the ambient temperature.
Allowable duty cycle (measured over one minute of continuous printing)
Amount of solid coverage Ambient temperature
25°C 35° C 50° C
20% 100% 50% 20%
40% 50% 25% 10%
100% 20% 10% 4%
Duty cycle
Percentage of time that the specified
“Amount of solid coverage” can be printed
during a one minute period of time.
Example: at 20% solid coverage,
35° C temperature, a 50% duty
cycle is to be used, resulting in
30 seconds of printing and
30 seconds without printing.
For reference:
• A typical receipt with text (contains some blank spaces) is
approximately 12% dot coverage.
• A full line of text characters (every cell on the line has a character in
it) is approximately 25% dot coverage.
• Graphics are approximately 40% dot coverage.
• Barcodes are approximately 50% dot coverage.
• A solid black line is 100% dot coverage.