| 摘要 |
A device for detecting the trailing end of a sheet inserted in a typewriter including a rod adjustably mounted on the carriage, extending below the platen and a transparent table for carrying the sheet. A reflective plate is positioned above the table, and the platen has a reflective coating. The rod supports a miniature light source and photo cell so that light returned from the reflective surfaces will generate a current in the photocell causing activation of an alarm. An alternative embodiment utilizes an electrically conductive rod arrangement including contact on the typewriter frame to create a closed circuit, the sheet passes through the contact point breaking the circuit.
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