Position transducer, and method for eliminating noise therefrom
First Claim
1. 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.
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Accused Products
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.
58 Citations
16 Claims
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1. A position transducer, comprising:
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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. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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2. 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:
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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. - View Dependent Claims (3, 4, 5)
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Specification