According to the type of sensor, touch screens can be divided into infrared touch screens, resistive touch screens, surface acoustic touch screens and capacitive touch screens.  

•   Infrared technology touch screen is cheap, but its frame is fragile, easy to produce light interference, distortion in the case of curved surface;

•   The design of capacitive touch screen is reasonable, but the problem of image distortion is difficult to be solved.

•   Resistance technology touch screen positioning accurate, but its price is quite high, and the fear of easy to scratch;

•   The surface acoustic touch screen solves various defects of previous touch screens. It is clear and not easily damaged. It is suitable for various occasions. 

Infrared touch screen

Infrared touch screen installs a circuit board outer frame in front of the display, and the circuit board arranges infrared transmitting tube and infrared receiving tube on the four sides of the screen, forming an infrared matrix of horizontal and vertical intersection.When the user touches the screen, the finger will block the two infrared rays passing through the screen, so it can tell where the touch point is on the screen.Any touch object can change the infrared on the contact to achieve touch screen operation.Infrared touch screen is free from current, voltage and static interference, suitable for some harsh environmental conditions.Its main advantages are low price, easy installation, no need for CARDS or any other controller, can be used in all levels of computer. 

Infrared touch screen is free from current, voltage and static interference, suitable for some harsh environmental conditions.Its main advantages are low price, easy installation, no card or any other controller, can be used at all levels of the computer. In addition, because there is no capacitor charging and discharging process, the response speed is faster than that of the capacitor type, but the resolution is lower.

Resistive touch screen

The outer layer of the resistive screen is usually a soft screen, which connects the inner contacts up and down by pressing.The inner layer contains a physical material called metal oxide, indium tin oxide (ITO), also known as indium oxide, which has a light transmittance of 80%.ITO is the main material used in both resistive touch screens and capacitive touch screens. Their working surface is ITO coating. Pressing the outer layer with fingertips or any object, the surface film is concave and deforms.According to the number of lead out of the screen, there are 4 lines, 5 lines and multiple lines, the threshold is low, the cost is relatively cheap, the advantage is not affected by dust, temperature, humidity.Disadvantages are also obvious, the outer screen is easy to scratch, can not use sharp object touch screen.Generally, multi-touch is not allowed, that is, only a single point can be supported. If two or more contacts are pressed at the same time, precise coordinates cannot be identified and found.To enlarge an image on the resistive screen, you can only click + multiple times.

Use pressure sensing for control. When the finger touches the screen, the two conductive layers make contact at the touch point, and the resistance changes.The signal is generated in both X and Y directions and then transmitted to the touch screen controller.The controller detects this contact and calculates the position of (X, Y), which operates in the manner of the analog mouse. Resistive touch screen is not afraid of dust, water and dirt, can work in harsh environment.However, because the outer layer of the composite film is made of plastic material, the antiknock property is poor, and the service life is affected to some extent. 

The resistive touch screen is controlled by pressure induction. Its surface is a layer of plastic, and the bottom is a layer of glass, which can withstand the interference of harsh environmental factors, but has poor hand feel and light transmittance. It is suitable for wearing gloves and occasions where hands cannot touch directly. 

Surface acoustic touch screen

Surface sound wave is a kind of mechanical wave propagating along the surface of medium. The touch screen is equipped with ultrasonic transducer in the corner.A high-frequency sound wave can be sent across the surface of the screen. When a finger touches the screen, the sound wave on the contact is blocked, thus determining the coordinate position.

Surface acoustic touch screen is not affected by temperature, humidity and other environmental factors, high resolution, with scratch resistance, long life, high light transmittance, energy

Maintain clear and clear image quality, most suitable for public use.But dust, water and dirt will seriously affect its performance, the need for frequent maintenance, keep the surface clean.

Capacitive touch screen

The touch screen works by using the body's electrical induction. A special metallic conductive material is coated on the surface of the glass. When a conductive object touches, the capacitance of the contact changes, so that the position of the touch can be detected.But touching with a gloved hand or holding an object that does not conduct electricity does not react because of the addition of a more insulating medium.

Capacitive touch screen can well sense light and quick touch, anti-scratch, not afraid of dust, water and dirt, suitable for use in harsh environment. But because the capacitance varies with temperature, humidity or environmental electric field, its stability is poor, the resolution is low, easy to drift.

Technical features of touch function

From the perspective of technical principle, the touch screen is a set of transparent absolute coordinate positioning system. First of all, it must be transparent. Therefore, it must solve the problem of transparency through material science and technology.Secondly it is absolute coordinates, finger touch which is which, don't need the second action, unlike the mouse, is a set of relative positioning system, we can notice that the touch screen software don't need a cursor, a cursor instead affects the user's attention, because the cursor is for relative positioning device, relative positioning device to move to a place where the first thing to know, which direction to go, all the time also need to constantly feedback to the user's current location is not appeared deviation. None of this is necessary for touch screens that take absolute coordinates; Then there is the ability to detect finger touch and determine finger position.

Screen transparency

Transparency, which directly affects the visual effect of the touch screen.Transparent have the level of transparency, the technology of infrared touch screen and surface acoustic wave touch screen separated only a layer of pure glass, transparent are outstanding, other touch screen that is going to do some scrutiny, "transparent", in the touch screen industry, is a very broad concept, a lot of touch screen is multilayer composite membrane, summed up in a little transparent only its visual effect is not enough, it should include at least four features:Transparency, color distortion, reflective and clarity, but also can be divided, such as reflective degree including mirror reflective degree and diffraction reflective degree, but touch screen surface reflective diffraction has not reached the level of CD disc, for the user, these four measures are basically enough.

As a result of the existence of pervious to light and wavelength graph, through the touch screen to see images of the inevitable produced the color distortion with the original image, feeling is just the color static image distortion, dynamic multimedia image is not very comfortable, color distortion degree is maximum color distortion degree of figure nature is as small as possible.What is usually referred to as transparency can only be the average transparency in the graph, of course, the higher the better. 

Reflective feature of touch screen

Reflective, mainly refers to the reflection caused by the mirror image overlap behind the shadow, such as shadow, Windows, lights.Reflection is the negative effect brought by touch screen, the smaller the better, it affects the browsing speed of users, and even cannot recognize image characters in serious cases. The use environment of the touch screen with strong reflection is restricted, and the lighting layout of the scene is forced to be adjusted.Most reflective problems of touch screen provides another after surface treatment of models: frosted surface touch screen, also called anti-dazzle type, the price is slightly higher, anti-glare coating significantly decline, suitable for daylighting is very sufficient hall or exhibition place, however, anti-dazzle type pervious to light quality and clarity also will have a substantial decline.Definition. Some touch screens are added with blurred handwriting, blurred image details, and the whole screen looks blurry and hard to see. This is poor definition.The problem of clarity is mainly the touch screen with multi-layer thin film structure, which is caused by repeated light and reflection and refraction between the film layers. In addition, the anti-dazzle touch screen also reduces the clarity due to the surface grinding.The clarity is not good, the eye is easy to be tired, also have certain harm to the eye, pay attention to distinguish when choose and buy touch screen.

Screen absolute coordinates

Touch screen is the absolute coordinate system, to choose which directly click that, and the mouse this kind of relative positioning system's essential difference is once in place of the intuitionistic. Absolute coordinate system is the feature of every location coordinates has nothing to do with the last position coordinates, touch screen in physics is a set of independent coordinate positioning system, every touch of data through the calibration data into screen coordinates, so that this requires a touch screen coordinates, no matter under what circumstances, the same point of the output data is stable, if not stable, so the touch screen can't guarantee the absolute coordinates positioning, point, this is the most afraid of touch screen problem: drift. In technical principle, any touch screen that cannot guarantee the same sampling data at the same point will have the problem of drift. At present, only capacitive touch screen has the phenomenon of drift. 

Screen detection location

To detect a touch and locate it, various touch screen technologies rely on their own sensors to work, and some touch screens are even a set of sensors themselves.The response speed, reliability, stability and life of the touch screen are determined by their respective positioning principles and sensors.

Touch screen with a convenient and intuitive, image is clear, strong and durable, and the advantages of saving space, the user as long as with the hand gently touch the glyphs on the computer screen or text can realize to the operation of the host and query, get rid of the keyboard and the mouse operation, thereby greatly improving the feasibility and security of the computer, make the human-computer interaction more directly.

Easy terminal operation

Just touch the relevant buttons on the computer screen with a finger to enter the information interface, which can include text, animation, music, video, games and so on. 

Software editing interface friendly

No need to understand the computer's professional knowledge, can clearly understand all the information, prompts, instructions on the computer screen, the interface for all levels, all ages of the majority of customers.

Touch screen displays rich information

The information variety is rich, can achieve the audio-visual all ready, changeable display effect.

Quick response of touch screen

The system USES the advanced technology, to the large capacity data query, the response speed is very fast.

The touch control function is safe and reliable

Long time continuous operation, no impact on the system, the system is stable and reliable, normal operation will not make mistakes, crash;Easy to maintain, the system includes a demo system interface is exactly the same management and maintenance system, can conveniently add or subtract data content, delete and modify management operations.

Good data extensibility

With good extensibility, can increase the system content and data.

Quick response of touch screen

Long time continuous operation, no impact on the system, the system is stable and reliable, normal operation will not make mistakes, crash;Easy to maintain.

SINDA is professional manufacturer of LCD display, TFT and OLED display in Shenzhen, China, we welcome you to share us any of the requirement regarding to displays.