INTERFACE UNIT FOR VEHICLE, AND DIGITAL TACHOGRAPH

摘要

PROBLEM TO BE SOLVED: To provide an interface unit for vehicle which converts a vehicle speed signal and a rotation pulse signal into a sharp rectangular wave by eliminating the fluctuation of a signal voltage and the influence of noise.SOLUTION: The interface unit for a vehicle includes: a clamp circuit 31 inputted with a vehicle speed pulse signal; a CR circuit 32 connected to an output side of the clamp circuit 31; and a Schmidt circuit 33 connected to the output side of the CR circuit 32. The clamp circuit 31 has: a diode D1 whose cathode is connected to a connector 51 (signal input side); and a resistor R1 whose one end is connected to an anode of the diode D1 and the other end is connected to a constant voltage V1. The CR circuit 32 comprises a resistor R2 whose one end is connected to the anode of the diode D1 and a capacitor C1 whose one end is connected to the other end of a resistor R2 and the other end is connected to the ground. The Schmidt circuit 33 comprises two Schmidt circuits IC1 and IC2.SELECTED DRAWING: Figure 3