Simplified heating elements applied to serial type thermal printing heads

Abstract

A breakthrough of a new thick-film thermal printing head has been studied by developing a simplified structure of the heating elements, and unique processing techniques. The fabrication process of the heating resistors is quite simple; they are formed in a belt shape (a single line with 0.25 mm width) by using a dispensing technique of thick-film resistor paste, and no resistor geometrically separated even if the resolution attained is 200 dots/inch. A resistance value between each I/O (input/output) terminal and a common terminal was equalised by adding a compensating resistor formed between the first and the common terminal, and also formed between the last and common terminal. Furthermore, to reduce thermal cross-talk generated in the adjacent resistors, an isolating resistor between heating resistors has been employed. The resistance value of the isolating and compensating resistor was effectively determined through resistor network analysis to prevent both thermal cross-talk and thermal smearing caused by substrate heating. Through this study, an advanced thermal printing head having a 32-dot heating element with 200 dots/inch has been developed with excellent printing quality and low power consumption (0.4 mJ/dot). Also, the printing life was satisfactorily long-term.