| 摘要 |
PURPOSE: To simply and quickly detect the failure of a variable display device by judging the variable display device as abnormal when no signal is received from sensors while stepping motors are rotated. CONSTITUTION: Stepping motors 77a-77c and photo-transistors (sensors) 98a-98c of a variable display device are connected to a microcomputer 130. When a power source is turned on, the stepping motors 77a-77c of the variable display device start driving and repeatedly feed step signals to the microcomputer 130. The microcomputer 130 detects reset values via a step counter based on the step signals. When the reset values are detected, whether the sensors 1-3 corresponding to the step signals are turned on or not is judged. When the on-state of the sensors 1-3 cannot be judged after a fixed time elapses, it is judged that there is the possibility of an abnormality on the stepping motors 77a-77c or the sensors 1-3, an alarm process is started, and a warning is issued. |
