Signal coordinate processing method, circuit and electromagnetic writing device

Abstract

The invention discloses a signal coordinate processing method, a circuit and electronic writing equipment. The circuit comprises an electromagnetic signal reception circuit, a rotary capacitive filter and an electromagnetic signal processing circuit, wherein the electromagnetic signal reception circuit is used for receiving electromagnetic signals transmitted by an electromagnetic pen; the rotary capacitive filter is controlled by PWM signals same as the electromagnetic signal in the aspect of frequency to filter the electromagnetic signal so as to filter the ineffective signals different from the electromagnetic signal in the aspect of frequency; the electromagnetic signal processing circuit is used for processing the filtered electromagnetic signal to obtain a signal coordinate position. The rotary capacitive filter is controlled by the PWM signals same as the electromagnetic signal transmitted by the electromagnetic pen in the aspect of frequency to filter the electromagnetic signal received by the electromagnetic writing equipment; under the control of the PWM signals, the working frequency of the rotary capacitive filter is relatively narrow in bandwidth and correct in filtration, so that the ineffective signals can be effectively filtered and the precision of recognizing the electromagnetic signal coordinates by the electromagnetic signal processing circuit in the writing process of the electromagnetic pen.

Description

technical field [0001] The invention relates to the technical field of signal processing, in particular to a signal coordinate processing method, a circuit and an electromagnetic writing device. Background technique [0002] Various electromagnetic pen technologies, whether active or passive, will use filter circuits to deal with external interference to improve the recognition of the coordinate position of the electromagnetic pen. If the interference signal that interferes with the electromagnetic pen is not detected If it is not processed, it will affect the recognition of the writing coordinate position of the electromagnetic pen, and if it is serious, it will lose its function. At present, there are three commonly used filtering methods for electromagnetic writing: 1. Software filtering, but a strong processor that can support Fourier changes is required. The operating frequency range of the electromagnetic pen is 50HZ-1MHZ frequency, and usually supports 500HZ-1M Fourie...

AI Technical Summary

Problems solved by technology

[0002] Various electromagnetic pen technologies, whether active or passive, will use filter circuits to deal with external interference to improve the recognition of the coordinate position of the electromagnetic pen. If the interference signal that interferes with the electromagnetic pen is not detected If it is not processed, it will affect the recognition of the writing coordinate position of the electromagnetic pen, and if it is serious, it will lose its function

At present, there are three commonly used filtering methods for electromagnetic writing: 1. Software filtering, but a strong processor that can support Fourier changes is required. The operating frequency range of the electromagnetic pen is 50HZ-1MHZ frequency, and usually supports 500HZ-1M Fourier changes. The processors are very expensive, and the cost of this filtering method is high; 2. Ceramic filter, ceramic filter frequency is fixed, the supply environment is poor, and the filter frequency selectivity is poor; 3. Active filters built with operational amplifiers, including low-pass Filters, high-pass filters, and band-pass filters, these filters require peripheral resistors and capacitors to form a specific frequency filter. The requirements for resistor values ​​and capacitor values ​​are high, and frequency shifts are prone to occur. Effectively filter out specific frequencies

Poor filtering will affect the recognition of the writing coordinate position by the back end and reduce the recognition accuracy

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