Method and apparatus for preventing unevenness in printing depth in a thermal printer

摘要

The present invention provides improved method and apparatus for preventing unevenness in thermal printers. Generally unevenness in thermal printers is a result of temperature variations between the heat generating elements thereof. The present invention seeks to prevent unevenness in printing by compensating the driving current of each heat generating element in response to its temperature. The temperature of the heat generating elements is determined by driving each element to a predetermined temperature while heating and determining the time interval which elapses between heatings. Further, thermal characteristics of the printing head can be used to compensate the driving current. Lastly, the driving current can be compensated with data which represents the time interval between printing successive lines of data.