| 摘要 |
<p>The system is composed of a shutter device and a rigid positioning device; the former comprises a hollow prismatic part, open in one of its bases, and a pulsation membrane, which closes the other base and extends into two tabs, one opposite the other. The positioning device has a central depression in which are found: an annular step; a flat circular bottom, in which there are two through-openings that can be covered by the tabs; and a prismatic cavity that can be fitted about the hollow prismatic portion; the bottom has means of support for the shutter device. <IMAGE></p> |
