| 摘要 |
The recording paper sensor of a facsimile machine includes: a light emitting unit generating light energy; a light receiving unit receiving light energy of the light emitting unit reflected by a recording paper; and a first and a second comparing units comparing an output signal of the light receiving unit and reference voltage(Vref1)(Vref2) set by resistance (R1, R2)(R3, R4) to output signal for simultaneously sensing residual amount of recording papers and an existence of recording papers.
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