| 摘要 |
PURPOSE:To prevent deterioration and breakdown of the thyristor by a method wherein a current is made to flow to other light emitting devices through a non- linear element connected in parallel with a light emitting device even when a trouble of opening is generated to the light emitting device. CONSTITUTION:When an optical gate signal generator 2 is operating, and when the trouble of opening is generated to the voluntary light emitting device 11ij, the current flows to the Zener diode 9ij connected in parallel with the troubled light emitting device 11ij thereof. Because the current thereof flows to the other sound light emitting devices connected in series with the troubled light emitting device 11ij, elimination of light gate signals of the whole light emitting devices in the series connection block thereof can be avoided. Accordingly, deterioration and breakdown of a thyristor 10ij corresponding to the block mentioned above can be prevented. |
