Craig & Antonelli
Photo coupler
 A photo coupler comprises a multilayer insulating substrate having a cavity on a predetermined portion and a first conductive layer at the bottom of the cavity and a second conductive layer on one surface of the insulating substrate. A light emitting diode is disposed in the cavity with a substantial light emitting zone thereof being in the cavity and is electrically connected to the first conductive layer. A photo responsive device is placed above the cavity on the substrate with the photo sensitive surface of the device facing the light emitting diode and being electrically connected to the second conductive layer. 
Hitachi, Ltd.
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additional inventional additional
Yasutoshi Tadahiko
Kurihara Miyoshi