TIRE INTERNAL PRESSURE ALARM DEVICE

摘要

PROBLEM TO BE SOLVED: To reduce malfunction of a tire internal pressure alarm device by eliminating influence of noise on a tire internal pressure signal detected by a pressure sensor. SOLUTION: When a digital transmission signal that tire internal pressure detected by the pressure sensor 11 is quantized by 500 nsec of a pulse width of 1-bit and a sampling frequency 34 kHz by a first CPU 1 is transmitted to a control circuit board B side by serial communication, the quantization signal and an AC signal from a transformer T2 for power source are added by using an addition circuit 15 and the digital transmission signal is transmitted after converted into a signal synchronized with the AC signal, and thereby influence of noise of the AC signal which is incorporated from a signal line and is corresponding to a switching frequency flowing in the transformer T2 for power source is eliminated.