Importance

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Abstract

A method and apparatus for maximizing print quality in a thermal printer uses a ribbon condition monitor to detect the condition of a multipass thermal ribbon. Data related to the condition of the thermal ribbon at each individual pixel is used to determine a custom energization signal for each thermal print element. In one embodiment, the system utilizes a history memory to track the prior heating history of each thermal print element and an ink memory to track the prior use of each location on the thermal print ribbon corresponding to the thermal print elements. The data from the history memory and the ink memory are combined to form an index to a table memory containing data corresponding to a plurality of energization signal levels for a particular print medium. The data in the table memory provides the custom energization signal for each of the thermal print elements. In an alternative embodiment, a light source and detector are used to determine the thickness of ink remaining on the thermal ribbon. The energization signal is adjusted to compensate for variations in the thickness of the thermal ribbon. In yet another embodiment, data is encoded at one end of a multipass thermal ribbon. The encoded data provides information related to the amount of usage of the thermal ribbon. The energization signal may be boosted for pixels along the edge of a graphic image so as to maximize the contrast of image edges. The system determines whether a particular pixel is located at the edge of a graphic image area and adjusts the energization signal correspondingly.

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First Claim