Thermal recording apparatus

A thermal recording apparatus for recording information along several recording lines in accordance with input recording signals which comprise black signals, said apparatus comprising:

• a plurality of aligned thermal resistive elements;
• a plurality of drive means each serially connected to a respective one of said thermal resistive elements for driving said resistive elements;
• a DC power source connected in parallel to said resistive elements and said drive means, said source having a smaller current capacity than the necessary current to simultaneously drive said resistive elements;
• a capacitor connected in parallel with said source;
• a detecting means for indirectly sensing the voltage across said capacitor by detecting the number of black signals which occur during a predetermined number of recording lines;
• and
• limiting means, coupled to said detecting means, for limiting the number of resistive elements simultaneously driven when said number of black signals exceeds a predetermined count, the predetermined count corresponding to a predetermined voltage of said capacitor.

A thermal recording apparatus for recording information in accordance with input recording signals comprising black signals, said apparatus comprising:

• a plurality of aligned thermal resistive elements;
• a plurality of drive means, each serially connected to a respective one said resistive elements, for driving said resistive elements;
• a shift register, coupled to each of said drive means, having a plurality of memory units, each unit corresponding to a respective drive means for supplying said input recording signals to said drive means;
• a DC power source connected in parallel to said thermal resistive elements and said drive means, said source having a smaller current capacity than the necessary current to simultaneously drive said resistive elements;
• a capacitor connected in parallel, with said DC power source;
• a resistor means connected in parallel with said capacitor for detecting a terminal voltage of said capacitor;
• a comparator means coupled to said resistor means for comparing the detected terminal voltage with a predetermined voltage;
• and,
• a control means for controlling the supply of said recording signals from the memory units to the drive means when the detected terminal voltage is less than said predetermined voltage.