Method for restraining noise by using control chip of touch screen

A control chip and anti-noise technology, applied in the input/output process of data processing, instruments, electrical digital data processing, etc., can solve the problems of poor versatility, complex implementation, high cost, etc., achieve a wide range of applications, eliminate power supply Effects of noise and small chip area

Inactive Publication Date: 2012-02-01
SHENZHEN BETTERLIFE ELECTRONICS SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0014] In order to reduce or even eliminate the noise of the touch screen, many solutions have been proposed. For example, the invention application of the Chinese published patent CN1503118A "Noise Device and Method for Preventing Touch Screen" proposes a method of using a clock circuit to control the received data to reduce noise. solution, but this invention application uses a whole set of specific devices to reduce the noise of the touch screen, which is relatively complicated and costly; such as Chinese published patent CN101246407 "A method for controlling static noise in a resistive touch screen and a corresponding touch screen" It is necessary to use a specific scanning signal to scan the touch screen to control the solution to reduce static noise, and the versatility is not strong; for example, the Chinese published patent CN101498975 "A Digital Filtering Method for Handling Touch Screen Flying Points" discloses a method that uses clipping to average Algorithm to reduce nois

Method used

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  • Method for restraining noise by using control chip of touch screen
  • Method for restraining noise by using control chip of touch screen
  • Method for restraining noise by using control chip of touch screen

Examples

Experimental program
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Effect test

Embodiment 1

[0031] If an AC power signal is coupled into the chip, such as Figure 7 Shown, the power supply noise signal frequency is 50Hz, the amplitude is 300V. The driving square wave signal is 200K, the reset time is 500nS, and the coupling capacitor C couple is 1pF, C sig is 1pF, the feedback capacitor C fb is 30pF. The AC power noise signal is linearized and calculated as a triangular wave signal, such as Figure 8 Shown:

[0032] Using the reset technique, the signal amplitude introduced by the AC signal at the output is,

[0033] Vout = V noise · C couple C fb · T reset 1 4 · T period = 300 · ...

Embodiment 2

[0036] Suppose an LCD driving signal is coupled into the chip. The driving square wave signal is 200K, the reset time is 500ns, and the coupling capacitor C couple is 1pF, C sig is 1pF, and the feedback capacitor is 30pF. The LCD driving signal is usually a square wave signal, which is the superposition of the fundamental wave signal and its harmonics. Here we only consider the fundamental wave signal, and assume that the fundamental wave frequency of the noise signal is 20K, and the amplitude is 20V.

[0037]Without the reset technique, this noise signal appears at the output with an amplitude of

[0038] Vout = V noise · C couple C fb · = 20 · 1 30 = 0.67 V

[0039] Using the reset technique, the signal ampl...

Embodiment 3

[0043] If an RF signal is coupled into the chip, the fundamental frequency of the noise RF signal is 100K, and the amplitude is 10V. The driving square wave signal is 200K, and the reset time is 500ns. The coupling capacitor C couple is 1pF, C sig is 1pF, and the feedback capacitor is 30pF.

[0044] Without the reset technique, this noise signal appears at the output with an amplitude of

[0045] Vout = V noise · C couple C fb · = 10 · 1 30 = 0 . 34 V

[0046] Using the reset technique, the signal amplitude introduced by the AC signal at the output is,

[0047] Vout = V noise · C couple...

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PUM

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Abstract

The invention relates to a method for restraining noise by using a control chip of a touch screen, in particular to a method for restraining noise such as RF (Radio Frequency) noise, power source noise, LCD (Liquid Crystal Display) noise and the like by using a control chip of a transmissive multipoint capacitor screen. A charge amplifier as well as a resistor and a capacitor which are respectively connected to the input end and the output end of the charge amplifier are provided in the method; the input end and the output end of the charge amplifier are also connected with a switch which is an NMOS (N-Channel Metal Oxide Semiconductor) switch, PMOS (P-Channel Metal Oxide Semiconductor) switch or COMS (Complementary Metal Oxide Semiconductor) switch. By adopting a resetting technology, noise charges are released when the charge amplifier is reset, and accumulation of the noise charges on a feedback capacitor is eliminated, therefore, the output of the amplifier is prevented from saturating due to the charge accumulation of the feedback capacitor and is kept within a reasonable range, a filtering effect is achieved, the power source noise, the LCD driving noise and part of RF noise can be completely eliminated, and the method is wide in application range and simple in realization, and meanwhile, the occupied chip area is minimum.

Description

【Technical field】 [0001] The invention relates to the field of capacitive touch screen control chips, and more specifically, relates to the suppression of RF noise, power supply noise, LCD noise and other noises by the transmissive multi-point capacitive screen control chip. 【Background technique】 [0002] With the popularization of computers, in the early 1990s, a new human-computer interaction technology appeared --- touch screen technology. This technology only needs the user to touch the icon or text on the computer screen to realize the operation of the host. It gets rid of the shackles of the keyboard and mouse and makes the human-computer interaction more direct. It is also the simplest and most convenient way of human-computer interaction. Today, touch screen technology has developed into four main types: resistive touch screen, capacitive touch screen, infrared touch screen, and surface acoustic wave touch screen. Among them, the capacitive touch screen is divided...

Claims

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Application Information

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IPC IPC(8): G06F3/044
Inventor 余佳
Owner SHENZHEN BETTERLIFE ELECTRONICS SCI & TECH
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