Abstract: A continuous-paper electrostatic printer saves paper by avoiding needless feeding of paper to the electrostatic printing section when there is no data to be printed. This is accomplished by providing a paper cutting means downstream of the paper holder of the printer and ensuring that paper is not transported upstream of the cutting means to the printer when there is no data to be printed and by ejecting the section of cut paper from the printer system at the same time.

Abstract: A thermal printer with a fault detection circuit for detecting faults in heating elements of the printer includes a print head containing heating elements and a heating circuit for each heating element and a power supply for supplying power to the heating elements. Power is supplied to the print head either directly through one terminal of the power supply or indirectly, during a test mode, through a fault detection circuit which is also connected to the print head. The fault detection circuit includes a constant voltage source, preferably formed of series-connected diodes, through which power flows to the print head. Current passing through the constant voltage source activates a photocoupler having an output the voltage of which determines whether a current is or is not flowing into the print head. A CPU which controls overall operations in the printer monitors the photocoupler and selects either a normal printing mode or a print head test mode.