| 摘要 |
PURPOSE:To detect an abnormal condition in a heating circuit part, by a method wherein printing data for a new line are inputted into a shift register, while printing data for the preceding printing are inputted into a comparing circuit to be compared with an output from the final stage of the shift register. CONSTITUTION:In response to a printing command, printing data are inputted from a printing data outputting part 22 into a printing memory 25 under the control of a printing controller 18. The first clock pulse CLK1 and the second clock pulse CLK2 are alternately outputted to output new printing data and the data of the previously printed line, respectively. The pulse CLK1 designates an address 3, while the pulse CLK 2 designates an address 2, and when inputting of a one-line amount of data is completed the contents of the shift register 20 are inputted into a latch circuit 17 at one stroke, and AND gates 16 are opened to pass an electric current to heating elements 14, thereby heating. When the heating element 14 is broken, a light-emitting element 32 does not emit light at the current-passing timing, so that the abnormal condition is detected. |
