| 摘要 |
PURPOSE:To improve the resolution of position detection by detecting the position difference between the zero-cross point of the detection signal of a pickup coil close to a position detection plate where conductors are connected to a common connection line successively at specific intervals and a prescribed point of control over the position detection plate. CONSTITUTION:A reference signal sent out of a reference transmitter 17 is frequency-divided by a frequency divider 18, whose frequency-divided signal a' turns on switches S1-S6 of a switch circuit S successively through a driving part 19, so that a current flows to each rectangular circuit successively by a voltage applied between terminals 13 and 14. When the pickup coil 20 approaches one of conductors L1-L6 on the position detection plate Po, a signal is generated and passed through an LPF21 to detect its zero-cross point through a zero-cross detector 22. A counter 23 is started by a frequency-divided signal b' from the frequency divider 24 and stopped by a zero-cross signal e'; the time between both signals is detected and from the ratio to the total driving time of the switches S1-S16, the position of the coil 20 on the detection plate Po is detected with high resolution. |
