| 摘要 |
PURPOSE:To inexpensively obtain a transistor having less irregularity and preferable unidirectional sensitivity characteristics by forming a plurality of shielding plates projected inwardly as supported by a metallic case to an incident optical path on a phototransistor element. CONSTITUTION:A phototransistor element 2 is fixed to the center of the flat surface of a metallic stem 4, and a cylindrical metallic case 3 having a plurality of parallel shielding plates 6 internally is mounted while engaging it with the step formed at the peripheral edge of the stem 4. At this time these shielding plates 6 are provided at an interval, and a selective light transmission opening is formed at the center. Thereafter, a flat plate glass 5 is engaged with the light incident plane integrally. In this manner, the light incident obliquely to the element 2 is shielded, and only the incident light at right angle is sensitized by the element. When suitably selecting the diameter d of the opening and the interval l of the plates 6, the directional property can be altered. |
