| 摘要 |
PURPOSE:To detect the states of plural on-off sensors with a smaller number of signal lines by parallel connecting the signal lines to the respective sensors via resistors respectively having prescribed resistance ratios, transmitting the on-off states in the form of the magnitude of electric current and subjecting the same to analog to digital conversion. CONSTITUTION:The switches SWa-SWd of the on-off sensors are respectively connected to the signal lines L1, L2 via the resistors Ra-Rd having the resistance value ratios of power of 2, i.e., 1:2:4:8. Current (i) flows to the line L2 and the output voltage V of a current/voltage converter 2 for the resistance Rf and operational amplifier OP attains the value of satisfy the equation when a reference voltage Vr is impressed to the line L1. The voltage V at which the on-off states of the respective sensors correspond to the binary bit such as 4-bit is processed by an analog to digital converter 1 and the states of the plural on-off sensors are detected by using a min. quantity, such as 2 sets, of the signal lines. In the equation, a-d: the constants which are 1 when the respective sensors SWa-SWd are off and 0 when the sensors are off.
|
