| 摘要 |
PURPOSE:To detect the dew condensation state of the entire optical system by comparing pattern information of a dew condensation gauge via an optical system of non dew condensation state with the pattern information of the same dew condensation gauge via the actual state optical system. CONSTITUTION:A pattern of a dew condensation gauge 4 installed adjacently to an original read face 8 is read by a read circuit 5 when the optical system is not in the dew condensation state and the output is stored in a storage circuit 6. The operation is applied once at, e.g., shipment. Then the pattern of the dew condensation gauge 4 is read again just before the original 3 attended with communication and a comparison discrimination circuit 7 compares it with the pattern stored in the storage circuit 6. When the pattern read in this case is coincident with the pattern stored in the storage circuit 6, it is discriminated that the optical system is not in the dew condensation state and the original 3 is led to the original read face 8 to apply transmission. On the other hand, when the read pattern is dissident with the pattern stored in the storage circuit 6, it is discriminated that the optical system is in the dew condensation state and the dew condensation processing is applied till the state reaches within an error of discrimination of non-dew condensation state.
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