| 摘要 |
PURPOSE:To make print sharp and uniformly stable, eliminate variable density irregularity and reduce the cost of a power supply by detecting duty per each dot of a printing pattern to be printed and driving a printing head pin depending on an excitation time after the correction corresponding to said duty. CONSTITUTION:A level detection circuit 2 detects a power supply voltage Vcc and reports it to a processor 4 through an input port 3. The processor 4 retrieves the first area 5a in a memory 5, selects an excitation time corresponding to a power supply voltage Vcc detected, then accumulates the time and calculates a printing duty by checking the dots of a character pattern to be printed from a line buffer 8. After this, the processor obtains a correction time based on a collation table and adds its correction value to the previously accumulated excitation time. Further, the processor sets an excitation time to be actually driven to a programmable timer and controls a pin excitation signal through a gate circuit 7. If an excitation time is set per dot in this way, print becomes sharp and uniformly stable and variable density disappears. |
