| 摘要 |
PURPOSE:To perform automatic printing in diazo copying whose density is uniformed for vaiours originals by setting the interval of detection points for the light transmittivity of an original on the basis of the rate of variation in photosensitive paper printing sensitivity with the light transmittivity of the original. CONSTITUTION:When the front end of the original moves to between an optical fiber 14 and a photosensor 16, an original light transmission detecting circuit 40 detects the light transmittivity of the original. The circuit 40 consists of the photosensor 16, a transistor (TR) 42 for amplification, and N sets of comparators C1-CN, etc. The rate of variation in printing speed is high at a low- transmittivity part of the original, so the detection point interval is narrowed down; when the transmittivity increases, the detection interval is widened. The output signal of the circuit 40 regarding optimum original light transmittivity is passed through an A/D converting and holding circuit 54 and then respective circuits 56, 62, and 66, and the signal is inputted to a driving motor speed control circuit 70, which controls a driving motor 28 to control the printing speed of photosensitive paper, performing the automatic printing in diazo copying whose density is made uniform. |
