Converging thousands – Rongda Zhiyuan, Wanrong Experiment is an integrator of overall design and construction.
With the increasing use of computers as a source of information, touch screen with its easy to use, durable, fast response, space saving and other advantages, so that more and more system designers feel that the use of touch screen does have considerable advantages, and what is the principle of touch screen, touch screen what types, touch screen how to buy and maintain?
1 Introduction to Touch screen
touch screen (touch screen), also known as “touch screen”, “touch panel”, is an inductive liquid crystal display device that can receive touch input signals, when touching the graphic button on the screen, the haptic feedback system on the screen can drive a variety of connecting devices according to a pre-programmed program, which can be used to replace the mechanical button panel. And through the LCD screen to create a vivid audio-visual effect. As one of the latest computer input devices, touch screen is currently the most simple, convenient and natural way of human-computer interaction. It gives multimedia a new look, is a very attractive new multimedia interactive equipment. It is mainly used in public information inquiry, leadership office, industrial control, military command, video games, song ordering, multimedia teaching, real estate presale and so on.
2 Touch Screen Features
1, transparent, it directly affects the visual effect of the touch screen. Transparency has the degree of transparency, infrared technology touch screen and surface acoustic wave touch screen is only separated by a layer of pure glass, transparent can be considered the best, other touch screen this point should be carefully considered, “transparent”, in the touch screen industry, just a very general concept, many touch screens are multi-layer composite films, only a transparent point to summarize its visual effects is not enough, It should include at least four characteristics: transparency, color distortion, reflection and clarity, can also be divided, such as the degree of reflection including mirror reflection and diffraction reflection, but the touch screen surface diffraction reflection has not reached the degree of CD disc, for users, these four measures are basically enough.
2, the touch screen is an absolute coordinate system, to choose where to directly point that, and the essential difference between the mouse and such a relative positioning system is the intuitive place. Require the touch screen set of coordinates in any case, the output data of the same point is stable, if not stable, then the touch screen can not guarantee absolute coordinate positioning, the point is not accurate, which is the touch screen most afraid of the problem: drift. In principle, all touch screens that cannot guarantee the same sampling data each time the same point is touched have the problem of drift, and only capacitive touch screens have drift at present.
3. Detect touch and locate. Various touch screen technologies rely on their own sensors to work, and even some touch screens themselves are a set of sensors. The respective positioning principles and the sensors used determine the response speed, reliability, stability and life of the touch screen.
3 Principle of touch screen
For ease of operation, people use touch screens instead of mouse or keyboard. When working, we must first touch the touch screen mounted on the front of the display with our fingers or other objects, and then the system can locate and select information input according to the icon or menu position touched by our fingers. The touch screen is composed of a touch detection component and a touch screen controller. The touch detection component is installed in front of the display screen to detect the user’s touch position and accept the rear touch screen controller; The main function of the touch screen controller is to receive touch information from the touch point detection device, convert it into contact coordinates, and then send it to the CPU, which can also receive the command sent by the CPU and execute it.
4 Touch Screen Types
According to the working principle of the touch screen and the medium for transmitting information, we divide the touch screen into four types, which are resistance type, capacitance induction type, infrared type and surface acoustic wave type.
1, resistive touch screen: is a completely isolated working environment to the outside world, not afraid of dust and water vapor, it can be touched with any object, can be used to write and draw, more suitable for industrial control field and limited use in the office.
2, capacitive touch screen: is the use of the human body’s current induction to work. The transmittance and clarity of the capacitive touch screen are better than that of the four-wire resistance screen, and of course can not be compared with the surface acoustic wave screen and the five-wire resistance screen. The reflection of the capacitor screen is serious, and the transmission rate of the four-layer composite touch screen of the capacitor technology is not uniform to the light of each wavelength, and there is a problem of color distortion, and the image characters are blurred due to the reflection of the light between the layers.
3, infrared touch screen: multi-level self-adjustment and self-recovery of hardware adaptability and highly intelligent identification, can be used for a long time in a variety of harsh environments. And can be customized for users to expand the function, such as network control, sound sensing, human body proximity sensing, user software encryption protection, infrared data transmission. The other major disadvantage of the original media promotion of the infrared touch screen is poor anti-violence, in fact, the infrared screen can choose any customer that is satisfied with the anti-riot glass without increasing too much cost and affecting the use of performance, which is other touch screens can not be copied.
4, surface acoustic wave touch screen: high clarity, good transmittance. High durability, good scratch resistance (with surface degree film relative to resistance, capacitance, etc.). Responsive. Not affected by temperature, humidity and other environmental factors, high resolution, long life (50 million times under good maintenance); High transmittance (92%) to maintain clear and transparent image quality; No drift, only need to install once correction; There is a third axis (that is, the pressure axis) response, which is currently used more in public places.
5 Touch Screen Option
1, when you get a touch screen to see if the touch screen is printed around the green border, if there is, you can probably guess is the insulation ink, but the insulation ink may also be translucent color. In any case, the design of insulating ink will be slightly worse than the quality of double-sided tape with substrate.
2, you can take a look at the design of the cable end, if the cable tail connection and the touch screen itself is not sticky enough, the touch screen is easy to break, if the touch screen is broken to repair the chance is not big.
3. You can hold the touch screen in your hand at a 60° Angle to see if there is a Newton ring generated on the surface, if there is a Newton ring generated touch screen, it means that the factory is not experienced enough in dealing with Newton rings.
4, touch the touch screen with your finger to feel whether the touch screen has an upper and lower layer, if you feel it, it means that the factory has a way to go to provide a good quality touch screen products.
6 Touch Screen Installation
First of all, after selecting the touch screen according to the size and shape of the display device (the shape here refers to whether the picture tube is flat, spherical or cylindrical), attach the frame of the touch screen to the display with double-sided tape, and then insert the control card into the expansion slot of the computer and connect it with the cable. If the touch screen is highly integrated and the control card is integrated into the frame, it is even easier to connect it to the RS-232, USB, or keyboard interface depending on the interface type provided by the touch screen. If it is an RS-232 interface, it also needs an external power supply; USB and keyboard interfaces provide power directly, requiring only one connection.
After the hardware is installed, power on the device and install the software. In addition to driving the touch screen, the role of the software installation is to calibrate the touch screen. The function of calibration is to make the effective area of the touch screen correctly correspond to the area of the image displayed by the display device, that is, to determine the effective boundary of the touch screen, so this calibration is called “edge to edge” calibration. According to the size of the image area of the display device, it is good to tap twice on the diagonal of the touch screen.
Once calibrated, set the way the touch screen reports coordinates to the host.
7 Touch Screen Maintenance
1, usually it is best to use the distribution of the touch pen to click the touch screen, try not to use other things instead. In particular, metal sharps are easy to damage the surface of the screen, and serious scratches can even cause the surface and inner layer of the screen, resulting in local necrosis of the touch screen;
2, do not use the touch screen in harsh environments. The use environment has an impact on the service life of the touch screen, too high or too low temperature, water and gas corrosion in the humid environment will shorten its service life;
3, when using, be sure to mount a protective film on the surface of the touch screen, which is a good way to extend the life of the screen.
8 The touch screen fault is rectified
1, touch screen can not be calibrated
1) If you are using a Lenovo host, the MOUSEWARE software pre-installed in it conflicts with the touch screen driver, please delete this software and restart the calibration program.
2) It is possible that before the host starts to load the touch screen driver, the touch screen control card receives the operation signal, please power off and restart the computer and recalibrate.
3) The touch screen driver may be installed abnormally, please delete the driver and reinstall it. (Delete from Control Panel HMI display Add Delete program.)
4) It is possible that after the acoustic screen is used for a period of time, the reflection stripes around the screen are covered with a lot of dust, so that calibration cannot be carried out. If you use our company’s KA cabinet, you can open the top cover and wipe with a dry soft cloth. Pay attention to the upper left, upper right and lower right transducers. Start the computer and calibrate.
2, The mouse stays at a certain point on the touch screen.
This is because the touch area of the resistance screen (the surface of the resistance screen is divided into two parts: the touch area and the non-touch area, and there is no reaction when clicking the non-touch area) is pressed by the display housing or the cabinet housing, which is equivalent to a certain point has been touched. If the cabinet housing presses down on the touch area, you can increase the distance between the cabinet and the monitor screen. If the monitor housing presses down on the touch area, you can try to loosen the screws on the monitor housing.
3, the touch screen work is not stable
In view of this phenomenon, we should focus on checking whether the wiring interface is loose, and whether the serial port and the interrupt number conflict.