| 摘要 |
A control keyboard for electric or electronic machines, with a first plate having a number of apertures, and keys mounted through these apertures; the keys have flanges of magnetic material on their lower portions to prevent the keys from slipping out. A second plate underneath the first plate has contacts cooperating with the key flanges. The first plate has an upper metal plate and a lower magnetic layer. The keys are movable between a first position when flanges are applied to the lower magnetic layer, apart from the contacts, and a second position where the flanges touch the contacts. The lower magnetic layer and the flanges return the keys from the second to the first position by magnetic attraction. An upper grid mounts the keyboard in a casing, with the upper metal plate between the lower magnetic layer and the upper grid. Each key has a body and a cap. A sheet of fluid-tight and resilient material may be clamped between the upper grid and the upper metal plate.
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