Position detection device

摘要

In a position detection device, an amplitude modulation is executed for AC excitation signals Sc using modulation wave signals. Differential amplifiers execute a voltage conversion of the modulated wave signal Sin, Cos to digital data SIN, COS and transmit them to a microcomputer. The microcomputer multiplies the modulated wave signals SIN, COS with parameters cos φ, sin φ, and executes a subtraction of the multiplied value to obtain an error-correlation value ε. An angle calculations section in the microcomputer receives a detected value εc obtained by multiplying the error-correlation value ε with a binary detection signal Rd. The binary detection signal Rd corresponds to a positive sign or a negative sign of the signal Sc. The sampling time of the AC excitation signal Sc is set to a time at which an absolute value of the AC excitation signal Sc exceeds a regulated value.

主权项

1. A position detection device comprising:
a computer system, including a central processing unit (CPU), the computer system being configured to provide a demodulation section for receiving a modulated wave signal which is obtained by an amplitude modulation of an alternating current excitation signal on the basis of position information of a target detection device to be detected, and demodulating the position information from the modulated wave signal by using a plurality of sampling values of the modulated wave signal during a period of the alternating current excitation signal, andthe demodulation section comprising:
an alternating current excitation signal sampling section configured to sample the alternating current excitation signal so that the number of the alternating current excitation signals sampled during a first period in which alternating current excitation signals has a positive value is equal to the number of the alternating current excitation signal during a second period in which the alternating current excitation signal has a negative value; a detection section configured to receive an output of the alternating current excitation signal sampling section, and execute an eliminating process of eliminating an influence caused by a sign of the alternating current excitation signal from the position information when the position information is demodulated from the received modulated wave signal; and an avoidance section configured to avoid using the alternating current excitation signal having not more than a regulated value in the demodulation of the position information, wherein the regulated value is more than a changed value of the alternating current excitation signal during a time difference between a sampling time of the alternating current excitation signal sampled by the alternating current excitation signal sampling section and the sampling time of the modulated wave signals.