Reference frequency automatic calibration method of an electromagnetic pen

Abstract

A reference frequency automatic calibration method of an electromagnetic pen comprises the following steps that an electromagnetic screen actively scans signals of the electromagnetic pen; Wherein theelectromagnetic screen repeatedly obtains a plurality of groups of frequency signal values of the signals of the electromagnetic pen from the absence to the presence, and each group of frequency signal values comprises a plurality of frequency signal values of the signals of the electromagnetic pen from the absence to the presence; the plurality of groups of frequency signal values are respectively filtered to obtain a plurality of to-be-judged reference frequencies; the plurality of to-be-judged reference frequencies are compared with reference frequencies originally stored in an electromagnetic screen; And if the difference between the plurality of to-be-judged reference frequencies and the reference frequency originally saved by the electromagnetic screen is within a threshold range, an average value of the plurality of to-be-judged reference frequencies is calculated, the reference frequency originally saved by the electromagnetic screen is replaced with the average value, and theaverage value is determined as the calibrated reference frequency.

Description

【Technical Field】

[0001] The invention relates to the field of electromagnetic screens, in particular to a method for automatically calibrating the reference frequency of an electromagnetic pen. 【Background technique】

[0002] In the electromagnetic screen system, the principle of pressure sensitivity is realized through different frequencies generated by the different strength of the electromagnetic pen tip. The greater the force on the electromagnetic pen tip, the greater the frequency change (depending on the internal circuit, the frequency change can be a large change or a small change). When the tip of the electromagnetic pen is not stressed, the pressure sensitivity is 0, and its frequency is a fixed value. Therefore, as long as the frequency when the pressure sensitivity is 0 is determined as the reference frequency, different pressure sensitivity can be achieved according to different changing frequencies. effect. The electromagnetic pen circuit has poor consistency due...

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