Printing head drive circuit for thermal printer

摘要

A drive circuit for a recording head of a thermogenetic recording apparatus comprises a series connection of a current limiting resistor and a variable resistor. The series connection is connected with a control input terminal of switching circuits adapted to selectively energize a plurality of groups of heat generating elements. A stabilizing power source circuit is connected with the current limiting resistor to maintain the voltage across the current limiting resistor or a current flowing therethrough constant. The current flowing through the series connection is thus kept constant so that a voltage for energizing the heat generating element groups is determined by a resistance of the variable resistor. The element group energizing voltage is controllable by adjusting the resistance of the variable resistor.