| 摘要 |
An alphanumeric keyboard arrangement contains a keyboard housing in whose cover a number of vertically movable keys (16) are arranged. A source (22) of electromagnetic radiation is arranged at one end of the housing and produces radiation which propagates in the housing. A scannable radiation detector (32) is provided at the opposite end of the housing. The key (16) is connected to a shadow mask (38) which has a shadow profile which corresponds to the digital code of the character assigned to this key. When a key (16) is pressed, the shadow mask (38) moves into the beam path and interrupts the latter in accordance with the shadow profile. This shadow profile is imaged on a detector surface (34) of the radiation detector (32). The imaging can then be converted into an electrical signal which specifies the digital code in a serial form. <IMAGE>
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