Electric resistance type touch screen control circuit

Abstract

The control circuit includes following parts: resistance type touch screen in use for receiving change of resistance, and generating changed signal; being connected to the touch screen, the driving tube is in use for ducting the change signal selectively; being connected to the touch screen, the analog-digital converter (ADC) is in use for carrying out analog-digital conversion for the change signal; and logic control module in use for controlling the driving tube. The control circuit also includes a sample holding circuit (SHC). Through the input end, SHC is connected to the touch screen; and through the output end SHC is connected to ADC.

Description

technical field [0001] The invention relates to a control circuit, in particular to a resistive touch screen control circuit. Background technique [0002] The touch screen consists of two transparent layers stacked one on top of the other. Among them, the four-wire and eight-wire touch screens include two layers of transparent resistive materials with the same surface resistance, and the five-wire and seven-wire touch screens include a resistive layer and a conductive layer. An elastic material is also used to separate the two layers. [0003] As shown in Figure 1, it is a schematic diagram of the control circuit of a four-wire resistive touch screen. The main part of the resistive touch screen is a resistive film screen 111, 112 that is very compatible with the surface of the display. This is a multi-layer composite film. A layer of glass or hard plastic plate as the base layer, the surface is coated with a layer of transparent metal oxide (transparent conductive resistan...

AI Technical Summary

Problems solved by technology

[0011] Therefore, the main disadvantages of this traditional touch screen controller circuit are: firstly, the analog-to-digital converter will introduce offset errors and gain errors, which in specific applications means that the touch screen cannot be displayed on the full screen; secondly, the analog-to-digital converter 107 The input terminal samples the divided voltage value of the resistor, and the on-resistance of the drive tubes 101, 102, 103, and 104 will vary with the power supply voltage, process and temperature.

The material and size of the touch screen will vary with different applications, resulting in different resistance values ​​of the screen, so that the voltage of ΔVn and ΔVp is not a constant value

This makes the offset error and gain error of the same touch screen controller different for different touch screens and power supply voltages, which increases the complexity of the application

Images