The difference between LCD capacitive screen and resistive screen

The difference between LCD capacitive screen and resistive screen

1. The screen body of the resistive touch screen is a multi-layer composite film with a layer of glass or plexiglass as the base layer. The surface is coated with a transparent conductive layer (ITO film), and the outer surface is hardened and smooth. Scratch-resistant plastic layer. Its inner surface is also coated with a layer of ITO, and there are many small (less than one thousandth of an inch) transparent isolation points between the two conductive layers to separate them. When the finger touches the screen, the two layers of ITO come into contact, and the resistance changes. The controller calculates the coordinates of the contact point according to the detected resistance changes, and then performs corresponding operations according to the coordinates. Therefore, this technology must apply force. To get the touch effect on the screen. The full name of the resistive screen is the resistive touch screen. The resistive screen is a sensor that converts the physical position of the touch point (X, Y) in the rectangular area into voltages representing the X and Y coordinates. Many LCD modules use resistive touch screens. This screen can use four, five, seven, or eight lines to generate screen bias voltage and read back the voltage at the touch point. The resistive touch screen is basically a structure of thin film and glass. The adjacent surfaces of the thin film and the glass are coated with ITO (Nano Indium Tin Metal Oxide) coating. ITO has good conductivity and transparency. When touch operation, the ITO of the lower layer of the film will contact the ITO of the upper layer of the glass, and the corresponding electrical signal will be transmitted through the sensor, and then sent to the processor through the conversion circuit, which is converted into the X and Y values on the screen through calculation to complete the point. The selected action is displayed on the screen.

2. The capacitive touch screen uses the current induction of the human body to work. The touch screen consists of a four-layer composite glass screen. The inner surface and interlayer of the glass screen are each coated with a layer of ITO, and the outermost layer is protected by silica glass with a thickness of only 0.0015mm. Layer, sandwich ITO coating is used as the working surface, four electrodes are drawn from the four corners, and the inner ITO is the screen layer to ensure the working environment. When a finger touches the touch screen, due to the electric field of the human body, the user's finger and the surface of the touch screen form a coupling capacitor, because high-frequency signals are connected to the working surface, and for high-frequency currents, the capacitor is a direct conductor, so the finger The point draws a small current. This current flows from the electrodes on the four corners of the touch screen, and the current flowing through these four electrodes is proportional to the distance from the finger to the four corners. The controller obtains the position information of the touch point by accurately calculating the ratio of these four currents. , Can reach 99% accuracy, with a response speed of less than 3ms.

3. Comparison of advantages and disadvantages of capacitive screen and resistive screen

The advantage of the resistive touch screen is that its screen and control system are relatively cheap, and the response sensitivity is also very good, and whether it is a four-wire resistive touch screen or a five-wire resistive touch screen, they are a work environment that is completely isolated from the outside world and are not afraid of dust. And water vapor, can adapt to various harsh environments. It can be touched with any object and has good stability. Capacitive screens can usually be made of hard glass, which feels better. Resistive screens are usually made of more than two layers of soft materials, and the screen will be slightly deformed during operation and feel slightly worse.