Touch detection method for electromagnetic screen and electromagnetic input device

Abstract

This application discloses a touch detection method and an electromagnetic input device for an electromagnetic screen. The electromagnetic screen includes multiple receiving coils for receiving electromagnetic wave signals from an electromagnetic pen and converting the electromagnetic wave signals into detection signals. The touch detection method includes: receiving detection data, which is obtained by performing ADC data sampling processing on the detection signals; constructing a detection data matrix based on the detection data; multiplying the detection data matrix with a preset demodulation matrix to obtain a demodulation result of the detection data; wherein the demodulation matrix is ​​based on IQ demodulation and preset filtering processing; and obtaining the touch position and touch pressure of the electromagnetic pen on the electromagnetic screen based on the demodulation result.

Claims

1. A touch detection method for an electromagnetic screen, wherein the improvement is that the electromagnetic screen includes multiple receiving coils, the receiving coils being used to receive electromagnetic wave signals from an electromagnetic pen and convert the electromagnetic wave signals into detection signals; The touch detection method includes: receiving detection data, wherein the detection data is obtained by performing ADC data sampling processing on the detection signal; constructing a detection data matrix based on the detection data; multiplying the detection data matrix with a preset demodulation matrix to obtain a demodulation result of the detection data; wherein the demodulation matrix is ​​based on IQ demodulation and preset filtering processing; and obtaining the touch position and touch pressure of the electromagnetic pen on the electromagnetic screen based on the demodulation result.

2. The touch detection method as described in claim 1, wherein, The demodulation matrix is ​​based on IQ demodulation and FIR filtering. The mathematical expression of the demodulation matrix includes: ; ; ; where is the demodulation matrix, is the in-phase local oscillator signal vector matrix based on IQ demodulation, is the quadrature local oscillator signal vector matrix based on IQ demodulation, is the sampling time of the detected data, is the frequency of the detected signal, and is the coefficient matrix of the FIR filtering process.

3. The touch detection method as described in claim 1, wherein, The demodulation matrix is ​​based on IQ demodulation and covariance filtering. The mathematical expression of the demodulation matrix includes: ; ; where is the demodulation matrix, is the in-phase local oscillator signal vector matrix based on IQ demodulation, is the quadrature local oscillator signal vector matrix based on IQ demodulation, is the time aggregation coefficient matrix, is the covariance filtering matrix, is the preset phase operator, is the time domain filtering coefficient matrix, and is the covariance matrix of the receiving coil.

4. The touch detection method as described in claim 1, wherein, The step of constructing a detection data matrix based on the detection data includes: constructing a matrix for the detection data of each receiving coil to obtain multiple detection data matrices; the step of multiplying the detection data matrix with a preset demodulation matrix to obtain a demodulation result of the detection data includes: multiplying each detection data matrix with the demodulation matrix of the corresponding receiving coil to obtain multiple demodulation results.

5. The touch detection method as described in claim 1, wherein, The step of constructing a detection data matrix based on the detection data includes: constructing a matrix from the detection data of multiple receiving coils to obtain a detection data matrix; the step of multiplying the detection data matrix with a preset demodulation matrix to obtain the demodulation result of the detection data includes: constructing a diagonal matrix from the demodulation matrices of multiple receiving coils and preset weighting coefficients to obtain a multi-coil coordinated demodulation matrix; and multiplying the detection data matrix with the multi-coil coordinated demodulation matrix to obtain the coordinated demodulation result of multiple receiving coils.

6. The touch detection method as described in claim 5, wherein, The step of multiplying the detection data matrix with the multi-coil coordinated demodulation matrix to obtain the demodulation result of multiple receiving coils includes: flattening the column vectors of the detection data matrix to obtain a single-column data matrix; and multiplying the single-column data matrix with the multi-coil coordinated demodulation matrix to obtain the demodulation result.

7. The touch detection method as described in claim 1, wherein, The demodulation result includes the in-phase component and the quadrature component of the detection signal; obtaining the contact position and contact pressure of the electromagnetic pen on the electromagnetic screen based on the demodulation result includes: obtaining the signal amplitude of the detection signal based on the in-phase component and the quadrature component; obtaining the contact position based on the signal amplitude; obtaining the phase of the detection signal based on the in-phase component and the quadrature component; and obtaining the contact pressure based on the phase.

8. The touch detection method as described in claim 1, wherein, The touch detection method further includes: transmitting the detection data matrix to a host computer, the host computer performing demodulation processing on the detection data to obtain demodulation verification results; receiving the demodulation verification results and adjusting the demodulation matrix based on the demodulation verification results and the demodulation results.

9. An electromagnetic input device, improved in that it includes an electromagnetic screen and a controller, the electromagnetic screen including a plurality of receiving coils for receiving electromagnetic wave signals from an electromagnetic pen and converting the electromagnetic wave signals into detection signals; the controller for performing a touch detection method as described in any one of claims 1 to 8.

10. The electromagnetic input device as described in claim 9, wherein, It also includes a signal acquisition unit, which is connected to the receiving coil and the controller. The signal acquisition unit is used to receive the detection signal, perform ADC data sampling processing on the detection signal, obtain the detection data, and transmit it to the controller.

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