Difference between capacitive screen and Resistive Screen

Difference between capacitive screen and Resistive Screen

 

1. resistive touch screen
　　
① They are a completely isolated work environment, not afraid of dust, water vapor and oil pollution
② It can be touched by any object and used for writing and painting. This is their great advantage.
③ The accuracy of the resistive touch screen only depends on the accuracy of A/D conversion, so it can easily reach 4096*4096? In comparison, the five-wire resistance is superior to the four-wire resistance to ensure resolution accuracy, but the cost is high, so the price is very high.
1.1 4-wire resistance Screen
When two transparent metal layers of four-wire resistance analog technology work, each layer adds a constant voltage of 5 V: a vertical direction, a horizontal direction. A total of four cables are required. Features: High Resolution, high-speed transmission response. Surface Hardness treatment to reduce scratches, scratches and prevent chemical treatment. With smooth and fog surface processing. One correction, high stability, never drifting.

1.2 5-wire resistance Screen
The base layer of the Five-wire resistance technology touch screen adds the Voltage Fields in both directions to the conductive working surface of the glass through the precision resistance network, we can simply understand that the voltage field in two directions is added to the same working surface, while the outer nickel-gold conductive layer is only used as a pure conductor, the position of the touch point is measured by the X-axis and Y-axis voltage values of the inner Ito contact points after touch. Four leads are required for the inner layer of the Five-wire resistive touch screen. The outer layer is only one conductor, and there are five leads for the inner layer of the touch screen. Features: High Resolution, high-speed transmission response. High surface hardness, reduce scratches, scratches and prevent chemical treatment. The same point can still be used for 30 million times. Conductive Glass is the substrate medium. One correction, high stability, never drifting. 5-wire resistive touch screen features high price and high environmental requirements

1. 3 Limitations of the Resistance Screen
Whether it's a four-wire resistive touch screen or a five-wire resistive touch screen, they are a completely isolated working environment, not afraid of dust and water vapor, it can be touched by any object, can be used to write and draw, it is suitable for industrial control and office space limited people. The common disadvantage of the resistive touch screen is that the outer layer of the composite film uses plastic materials. People who do not know it are too hard or the use of acute touch may scratch the entire touch screen and lead to decommission. However, within the limits, the scratch will only hurt the external conductive layer. The scratch of the external conductive layer does not matter for the touch screen with five-wire resistance, but is fatal for the touch screen with four-wire resistance.

　　
2. capacitive touch screen
　　
2.1 capacitive technology Touch Screen
It uses the current sensing of the human body to work. Capacitive touch screen is a layer-4 composite glass screen. The inner surface of the glass screen and the interlayer are coated with an ITO layer. The outermost layer is a layer of glass protection layer, and the interlayer Ito coating is used as the working face, four electrodes are extracted from the four corners, and the inner ITO layer is a shielding layer to ensure a good working environment. When the finger is touched on the metal layer, due to the human electric field, the user and the touch screen surface form a coupling capacitor, for high-frequency current, the capacitor is a direct conductor, so the finger sucked a small current from the contact point. The current flows out of the electrodes on the four corners of the touch screen, and the current flowing through the four electrodes is proportional to the distance from the fingers to the four corners. The controller accurately calculates the ratio of the four currents, obtains the position of the touch point.

2.2 capacitive touch screen Defects
The light transmittance and definition of capacitive touch screen are better than that of four-line resistive screen. Of course, it cannot be compared with the surface acoustic screen and the five-line resistive screen. The capacitive screen is highly reflective. In addition, the four-layer composite touch screen of Capacitive technology has uneven light transmittance of various wavelengths, which causes color distortion. Due to the reflection of light between layers, it also causes blurred image characters. In principle, the capacitive screen uses the human body as an electrode of a capacitor element. When there is a conductor close to the interlayer Ito working face and a sufficient amount of capacitance is coupled, the current is enough to lead to the misoperation of the capacitive screen. We know that although the capacitance value is inversely proportional to the distance between Poles, It is proportional to the relative area and also related to the insulation coefficient of the medium. Therefore, when a large area of palm or handheld conductor is close to the capacitive screen rather than the touch, it can lead to the incorrect action of the capacitive screen. in wet weather, this situation is particularly serious, if you hold the monitor in your hand and the palm is close to the monitor within 7 cm or the body is close to the monitor within 15 cm, the screen may be mistakenly operated.
Another disadvantage of the capacitive screen is that it does not respond when a gloved hand or an object without conductive hand is touched, because it adds more insulating media. The main drawback of the capacitive screen is drift: when the ambient temperature and humidity change, the Environmental electric field changes, it will cause the drift of the capacitive screen, resulting in inaccuracy. For example, when the screen is turned on, the temperature of the monitor increases, causing drift: when the user touches the screen, the other hand or one side of the body is close to the monitor, and large objects near the capacitive touch screen are moved back to drift, when you touch the screen, if someone comes around to watch it, it will also cause drift. The reason for the capacitive screen drift is the inherent technical deficiency, the environmental potential surface (including the user's body) although far away from capacitive touch screens, they are much larger than the finger area, and they directly affect the determination of the touch position. In addition, in theory, many linear relationships are actually non-linear. For example, the total electric traffic consumed by people with different weights or different degrees of moisture on their fingers is different, however, the changes in the total electrical flow and the changes in the four sub-electric flows are non-linear. The custom Polar Coordinate System of the four corners used by the capacitive touch screen does not have the origin of the coordinates, after drifting, the controller cannot detect and recover, and after four A/D completes, the calculation process from the four traffic separation values to the X and Y coordinate values of the touch point in the Cartesian coordinate system is complex. Because there is no origin, the drift of the capacitive screen is cumulative, and calibration is often required at the work site.
The outermost protection glass of capacitive touch screen has good anti-scratch performance. However, if you are afraid of hitting your nails or hard objects, hitting a small hole will hurt the interlayer Ito, whether it is damage and interlayer Ito or damage the inner surface ITO layer during installation and transportation, the capacitive screen will not work normally.
This article is from: I love R & D network (52rd.com)-R & D Base Camp
Http://www.52rd.com/Blog/Detail_RD.Blog_jia_yan_cn_27556.html: