| 摘要 |
PURPOSE:To detect correctly a rotation synchronizing signal by AC combining electric signals from a pohoto-electric element, amplifying and saturating signals to positive and noise to negative. CONSTITUTION:DC component is removed from electric signals 21 obtained from a photo-electric element 1 by a capacitor 2, and amplified sufficiently by an amplifier 3. The output 32 is divided into two, and one is inputted to a Zener diode 4 and compared with Zener voltage V24, and binary coded signals 62 are outputted from an amplifier 6. Negative component is removed from another output and integrated by an integrator 8. The output 82 is compared with Zener voltage V29 of a Zener diode 9 and gate mark 112 is outputted from an amplifier 11. a monostable multivibrator 12 is triggered by falling edge of the gate mark 112, and gate output 122 is outputted. The binary coded signals 62 and gate output 122 are inputted to a logical product element 13, and rotation synchronizing signals are outputted from its output terminal 133, and rotation synchronizing signals can be detected correctly from output electric signals of the photo-electric element of low S/N ratio.
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