| 摘要 |
PURPOSE:To improve a detection speed by a method wherein outputted printing data are compared with printed data per bit, data of the difference are accumulated, whether a ratio of the accumulated data to the sum of the both data meets a fixed value is checked, and based on this result, the level of a printing density is detected. CONSTITUTION:Printing data are read from a data memory circuit 8 and printed for one line. Upon completion of printing, a printing medium is fed to a printing data read-out position by a printing medium feed mechanism 10. The printed part is read by a reading sensor 11, and the result is stored in the data memory circuit 8. When the reading is completed, the read data is compared with the stored printing data, and the difference is stored in the data memory circuit 8. In the second and succeeding printing actions, the data are similarly compared, and the difference is accumulated and stored. If a ratio of the sum of all the read data and printing data stored in the circuit 8 to the accumulated data is a fixed value or more, a CPU 13 judges a normal completion; if it is less than the fixed value, an indication of suggesting a ribbon replacement is conducted by an alarm circuit 14; and if it is much lower, an indication is conducted by an alarm circuit 15, a device is brought to a stop, and a ribbon is replaced immediately. |
