US 5,691,512 A · Position transducer, and method for eliminating noise therefrom

Abstract

A position transducer, and a noise elimination method for eliminating a noise component included in a received signal of the position transducer irrespective of the frequency band of the noise component. A position transducer calculates coordinates of a position indicator by effecting predetermined signal processing on the basis of a received signal developed in one of a plurality of loop coils, arranged side by side, as a result of electromagnetic interaction between the loop coil and the position indicator. The position transducer is further provided with a subtraction means which extracts an amplitude level corresponding to the signal developed in the loop coil only resulting from the electromagnetic interaction, for each loop coil, by subtracting a noise level obtained from a signal received when a transmission means interrupts transmission, from a signal received when the transmission means carries out transmission.

Claims16

Dependent claims

A position transducer, comprising:

a plurality of loop coils arranged side by side in a direction of position sensing;
a position indicator for electromagnetic interaction with one of said loop coils;
a transmission means for selectively transmitting or interrupting a first signal to said one of said loop coils;
a receiving means for receiving a second signal from said one of said loop coils;
a first memory means for storing a level of said second signal, said level being obtained as a result of processing of said second signal;
subtraction means for extracting an amplitude level, corresponding to said second signal developed in said one of said loop coils as a result of the electromagnetic interaction of said position indicator with said one of said loop coils, by subtracting a noise level obtained from a third signal received when transmission of said first signal is interrupted, from said second signal level;
and
processing means for calculating coordinates of said position indicator based on said amplitude level.

5 more elements

A position sensing method, for use in a position transducer having a plurality of loop coils arranged side by side in a direction of position sensing, and a position indicator for electromagnetic interaction with one of the loop coils, said method comprising the steps of:

selectively transmitting and interrupting a first signal to the one of the loop coils to cause electromagnetic interaction with the position indicator;
receiving a second signal from the one of the loop coils;
storing in a first memory means a level of the second signal, the level being obtained as a result of processing the second signal;
obtaining an amplitude level, corresponding to the second signal as a result of the electromagnetic interaction of the one of the loop coils with the position indicator, by subtracting a noise level obtained from a third signal received when the first signal is interrupted, from the second signal level;
and
calculating coordinates of the position indicator based on the amplitude level.

3 more elements

Dependencies are inferred from the claim text.

Position transducer, and method for eliminating noise therefrom

Life of this patent

Position transducer, and method for eliminating noise therefrom

Life of this patent

Abstract

Claims16