| 摘要 |
PURPOSE:To obtain a FAX receiver where no high-precision crystal oscillator is required, by detecting whether a picture signal of a width wider than that of the synchronizing signal exists in the facsimile FAX signal or not to perform independent synchronization or transmission synchronization. CONSTITUTION:Input FAX signal A is integrated by 2, and signal components of a narrow width included in signal A are eliminated by comparator 3, and signal C of a width wider than that of the synchronizing signal is extracted and is inputted to retrigger monostable multivibrator 4. The operation time of multivibrator 4 is set to a time slightly shorter than the main scanning time and falls only at the scanning period end when no picture signal components are included in signal C, and output signal D is inputted to monostable multivibrator 5 whose operation time is set to a time longer than the synchronizing signal. When AND between the output of multivibrator 5 and signal A is operated in 6, only the synchronizing signal of signal A is led out and is inputted to monostable multivibrator 7, and output signal G is inputted to synchronizing generator 9 to generate the driving synchronizing signal of FAX receiver 13. If a wide-width picture signal exists in signal A, signal E is not generated, and independent synchronization is performed by the signal from crystal oscillator 11. |
