Bidirectional printer with voltage compensator

Claim 1

A battery operated serial printer having a print head moveable in reciprocatory movement along a line upon which characters, symbols, and other print elements are to be printed to print data on a printing sheet by performing printing in a normal direction from the beginning of the line and in a reverse direction from the end of line, said printer comprising: a drive unit for moving said print head in a reciprocatory movement; a battery power source connected to said drive unit for powering said drive unit; a printing control unit for causing said print head to perform a printing operation; a voltage level sensing means operatively connected to said power source for determining the voltage level supplied by said power source to said drive unit when said printing operation is commenced; memory means connected to said voltage level sensing means and storing therein a reference value corresponding to a sensed normal voltage level of said power source and a plurality of correcting values each corresponding to a sensed voltage level less than said normal voltage level; and, a control means for controlling said printing control unit, said drive unit, said voltage sensing means and said memory means so as to select one of said correcting values when a sensed voltage level is less than said normal voltage level and apply said correcting value to said printing control unit and said drive unit whereby to inhibit said printing control unit from initiating printing until said printing head comes into proper character alignment position of said normal or reverse printing.