| 摘要 |
PURPOSE:To automatically request maintenance to a maintenance department, etc., by transmitting the output of a protection circuit representing the operating state of an individual display to a central control part by connecting in series or in parallel. CONSTITUTION:The display 3 provided with a display element 4 and driving circuits 5, 6 for display element and a control circuit 7 are connected in multiple stages, and the protection circuit 8 which monitors the operating state of the individual control circuit 7 and detects normalcy/abnormality is provided at the individual display 3. The protection circuit 8, when detecting the abnormality of the individual control circuit 7, stops a signal to be sent to a row electrode driving circuit 5 and a column electrode driving circuit 6. and stops a function as the display. Furthermore, the output of the protection circuit 8 is set so as to go to an 'H' level in a normal operation and to an 'L' level in an abnormal operation, and it is added from a transmission circuit 9 to a signal line group 2, and is connected in series sequentially in a direction from a terminal display to the central control part 1. Therefore, it is possible to detect that abnormality occurs in either directly connected individual display 3 when the level is the 'L' level by monitoring the level of the signal line group 2 by the central control part 1. |
