| 摘要 |
<p>PURPOSE:To decrease the number of components, and to miniaturize the title switch by forming a fifth conductor electrically connected to a first conductor as the gate of an FET on the surface of a fourth P-type region as a guard ring. CONSTITUTION:A first conductor 8 is connected electrically to a fifth conductor 15 formed on the surface of a fourth P-type layer 14 as a guard ring in order to obtain potential in the gate of an FET. When voltage is applied between external leading-out terminals A, K and the value reaches a certain extent or more (approximately several V), divided voltage between the terminals A, K is applied to the fourth P-type layer 14 as the guard ring. Voltage is applied to the first electrode 8 as the gate of the FET through the fifth conductor 15, and a thyristor composed of a P-N-P-N element is not turned ON even when a light-emitting diode 17 is turned ON and light-emitted and brought to an operable state (a standby state) because the FET is turned ON and currents are made to flow through the FET side when the voltage is made higher than the threshold voltager of the FET.</p> |
