The working principle and advantages and disadvantages of capacitive touch screen
Author: Shenzhen CDTech Electronics LTD. issuing time:2017-07-25 14:34:18Pageviews:1675【smallinBig】
Touch screen products in a few years ago is not very hot, then touch screen is only used in PDA, TablePC and some other products. But in recent years, with the application of the touch screen graduall...
Touch screen products in a few years ago is not very hot, then touch screen is only used in PDA, TablePC and some other products. But in recent years, with the application of the touch screen gradually increased, regardless of mobile phones, cameras or portable audio and video players, are competing to launch the configuration of the touch screen products. And as people touch the screen products more and more touch screen products in the past two years have been recognized by more people, the pace of development gradually accelerated.
Capacitive touch screen and the traditional resistive touch screen is very different. Resistive touch screen at work can only determine a touch point, if the touch point in more than two, you can not make the right judgments, so the resistive touch screen is only applicable to click, drag and some simple Action judgment. The capacitive touch screen multi-touch, you can split the user's touch for the acquisition of multi-point signal and determine the meaning of the two signals to complete the complex action to determine.
Use two fingers of the stretch, transposition can be completed on the screen, such as zoom, rotate this fun operation, which in the capacitive touch screen before it is almost unthinkable. Apple iPhone after the listing, and soon caused a wave of touch; soon after, Apple and win, launched the same support for multi-touch iPodtouch (in fact, it is equivalent to a simplified version of the iPhone), the same users and media Sought after.
In fact, the realization of the principle of touch screen roughly the same, are in the ordinary LCD screen to increase the transparent touch panel. And we call the resistive and capacitive and other types, it is based on the working principle of the different division. The current classification of the touch screen are resistive, capacitive, infrared, surface acoustic four types. In real life we have the most contact or resistive touch screen, it has been widely used in mobile phones and portable digital products.
Resistive touch screen works
In the analysis of capacitive touch screen principle, we first come to understand the working principle of resistive touch screen. Resistive touch screen is mainly used to control the pressure sensor. It is composed of a display screen and a close contact with the display of the resistance film screen. The resistive film screen is usually divided into two layers, one layer is made of glass or plexiglass base layer, the surface coated with a transparent conductive layer; outside the base layer pressing our usual direct contact with hardened and scratch-resistant plastic layer, There is also a layer of conductive layer inside the plastic layer, between the two conductive layer is separated. When we touch the screen with your fingers or other objects, the two conductive layers contact, the resistance changes, the controller according to the specific changes in resistance to determine the coordinates of the contact point and the corresponding operation.
Capacitive touch screen works
And resistive touch screen is different from the capacitive touch screen is the use of the body's current sensing work. Capacitive touch screen sensor screen is a four-layer composite glass screen, the glass screen of the inner surface and the sandwich coated with a layer of conductive layer, the outermost layer is a thin layer of siliceous glass protective layer. When we touch the screen with the finger on the sensor screen, the body's electric field and the touch screen and the surface of the touch screen to form a coupling capacitor, for high-frequency current, the capacitor is a direct conductor, so the fingers from the contact point suction a small current The This 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 finger to the four corners. The controller calculates the position of the touch point by accurately calculating the four current ratios The
Capacitive touch screen advantage
1. Operation novelty. Capacitive touch screen support multi-touch, more intuitive operation, more fun.
It is not easy to touch. As the capacitive touch screen needs to be sensed to the body of the current, only the human body to its operation, with other objects will not touch the corresponding, so the basic to avoid the possibility of false touch.
3. High durability. Compared with the resistive touch screen, capacitive touch screen in the dust, water, wear and other aspects of a better performance.
Capacitive touch screen shortcomings
As the current legitimate red touch screen technology, capacitive touch screen, although the interface with gorgeous, multi-touch, only the human body and other advantages, but at the same time, it also has the following shortcomings:
1. accuracy is not high. For technical reasons, the capacitive touch screen accuracy than the resistive touch screen is also lacking. And can only use the fingers to enter, in the small screen is also difficult to achieve more complex identification of handwriting input.
2. Affected by the environment. Temperature and humidity and other environmental factors change, it will cause capacitive touch screen instability or even drift. Such as the use of the user at the same time the body close to the screen may cause drift, even in crowded crowd operation will also cause drift. This is mainly due to the working principle of capacitive touch screen technology, although the user's fingers from the screen closer, but there are many near the screen much larger than the fingers of the electric field at the same time, it will affect the touch position to judge.
3. High cost In addition, the current capacitive touch screen in the touchpad attached to the LCD panel steps there are still some technical difficulties, the yield is not high, so virtually increase the cost of capacitive touch screen.
In the past, due to cost and technology and other factors, resistive control panel is used far more than the capacitive touch technology. But in the near phase, with the progress of technology and batch, capacitive touch screen prices are declining, and resistive touch screen price gap is getting smaller and smaller, in the price gradually have the ability to compete with the resistance touch screen The
With the Apple iPhone, iPodTouch and other products of the fire, not only the major manufacturers have begun to capacitive touch screen product development, and even many 3M, Synaptics touch screen manufacturers such as a large number of follow-up, have put into the capacitive touch screen research and development And production. I believe that with the continuous escalation of competition, capacitive touch screen in the short term there will be great development; and capacitive touch screen applications will not just the existing mobile phones, portable audio and video players and other products, but also to the camera, GPS navigator, game consoles and other products on the expansion.