Touch screen, also known as "touch screen" or "touch panel", is an inductive liquid crystal display device that can receive input signals such as contacts. When it touches the graphic button on the screen, the touch screen The haptic feedback system can drive various connection devices according to a pre-programmed program, and can be used to replace the mechanical button panel and create a live-action audio and video effect through the liquid crystal display screen. As the latest computer input device, the touch screen is the simplest, most convenient and natural way of human-computer interaction. It gives multimedia a new look and is an attractive new multimedia interactive device.
1 touch screen operation method
1. Open the "Start" menu, right click on "Computer", select "Properties" in the pop-up shortcut menu to open the system properties window. Under the "System" category, there is a property called "Pen and Touch", as long as it is displayed as "Available", it means that this computer supports touch operation, if it is displayed as "single touch", it means The computer supports single-touch, that is, it can be operated with one finger; if it is displayed as "multi-touch", it means that this computer supports multi-touch, and can operate with two or more fingers at the same time.
2, after clicking the left and right button operation, there is a more difficult problem, that is, when the pointing operation of the mouse is used, the mouse pointer is pointed to the file on the screen, and the system will automatically display the relevant information by using the screen prompt. Information about the file. However, when using the touch mode operation, this pointing operation is not easy to implement. If the device uses an electromagnetic induction touch screen, then the stylus can be hovered at a distance of about 1 cm above the screen to achieve a "pointing" operation; however, many devices, especially multi-touch devices, use a lot of pressure. Screen, which requires the finger to be close to the screen surface to take effect, in this case how to "point" instead of "left click"?
3. Open the “Control Panel”, go to “Hardware and Sound”, then “Pen and Touch”, open the “Pen and Touch” dialog box and switch to the “Touch” tab. Under the “Touch Pointer” option, select “With Screen” The touch pointer is displayed when the item on the interaction.
4. Click the “Advanced Options” button to open the Advanced Options dialog box, where you can set the virtual mouse displayed on the screen as needed, such as the left or right hand habit, the transparency and size of the virtual mouse, and the moving speed of the cursor. , after setting, click the "OK" button to close all open dialogs
After the above settings, after tapping the screen with your finger or stylus, a virtual mouse pattern appears around the touch contact, then you can drag the mouse with your finger or stylus to move the pointer, or click on it. The left and right buttons of the mouse implement a mouse click operation.
2 touch screen theory
1, surface acoustic wave screen
The three corners of the sound wave screen are respectively affixed with transducers for transmitting and receiving sound waves in the X and Y directions (transducers: made of special ceramic materials, divided into transmitting transducers and receiving transducers. The electrical signal sent by the touch screen cable is converted into acoustic energy and the surface acoustic wave energy condensed by the reflective fringes becomes an electrical signal.), the four sides are engraved with reflective stripes of the reflected surface ultrasonic waves. When a finger or a soft object touches the screen, part of the sound wave energy is absorbed, and thus the received signal is changed, and the X, Y coordinates of the touch are obtained by the processing of the controller.
2, four-wire resistance screen
The four-wire resistive screen is covered with two transparent conductive layers ITO between the surface protective coating and the substrate (ITO: indium oxide, weakly conductive, characterized by a thickness of less than 1800 angstroms (A = 10-10 meters)) It will suddenly become transparent, and then the light transmittance will decrease. When the thickness reaches 300 angstroms, the light transmittance will rise again. It is the main material of all resistive screens and capacitive screens.), the two layers correspond to the X and Y axes respectively. Insulated with fine transparent insulating particles, the pressure generated when the touch is made to turn on the two conductive layers, and the X, Y coordinates of the touch are obtained due to the change in the resistance value.
3, five-wire resistance screen
The base layer of the five-wire resistive screen is covered with a transparent conductive layer ITO which adds the voltage fields in the X and Y directions to the same layer, and the outermost nickel-gold conductive layer (nickel-gold conductive layer: used only as a pure conductor, when When touching, the position of the touch point is measured by means of time-sharing to detect the X-axis and Y-axis voltage values of the contact point. The inner layer ITO requires four leads and one outer layer, and a total of five leads.
4, capacitive screen
The surface of the capacitive screen is coated with a transparent conductive layer ITO, the voltage is connected to the four corners, and the small DC electric diffusing part is on the surface of the screen to form a uniform electric field. When the screen is touched by the hand, the human body acts as a coupling capacitor, and the current is collected from the four corners of the screen to form a coupling capacitor. At one pole, the coordinates of the touch are obtained by the controller calculating the relative distance of the current to the touch position.
3 touch screen classification
1, infrared technology touch screen
The touch screen is composed of infrared transmitting and receiving devices mounted on the outer frame of the touch screen. The transmitting device forms an infrared detecting net on the surface of the screen, and any object can change the infrared rays of the contact to realize the detection of the touch. The infrared touch screen is immune to current, voltage and static electricity. It is suitable for harsh working conditions, low price, easy installation and fast response. Infrared applications are now becoming more and more popular. They are generally used in large-scale devices, such as the large TVs on the TV. The life expectancy is high, the accuracy is high, the multi-point is supported, and the light transmittance is the best, up to 100%.
2, surface acoustic wave touch screen
Surface acoustic waves are mechanical waves that propagate along the surface of the medium. Such touch screens consist of a touch screen, a sound wave generator, a reflector, and a sound wave receiver. The sound wave generator generates a high frequency sound wave across the surface of the screen, and when the finger touches, the sound wave on the electric shock is blocked, and the sound wave receiver thereby determines the coordinate position. The surface acoustic wave touch screen is not affected by environmental factors such as temperature and humidity. The resolution is extremely high, it has excellent scratch resistance, long service life, good light transmittance, no drift, and the surface is not afraid of scratching. The disadvantage is that it is afraid of water and oil. Dirty to be maintained.
3, resistive touch screen
The resistive touch screen is a multi-layer composite film that matches the surface of the display. The structure is made of a layer of glass as a base layer, a transparent conductive layer (ITO, indium oxide) is coated on the surface, and the upper layer is covered with a scratch-resistant plastic layer. The inner surface is also coated with a layer of ITO, four-line and eight-line. The touch screen consists of two layers of transparent resistive material with the same surface resistance. The five-wire and seven-wire touch screens consist of a resistive layer and a conductive layer, usually with a small number of tiny layers (less than one thousandth of an inch) between the two conductive layers. ) The transparent isolation points separate them. When the pressure on the surface of the touch screen (such as pressing through a pen tip or finger) is large enough, contact is made between the top layer and the bottom layer. All resistive touch screens use a voltage divider principle to generate voltages that represent the X and Y coordinates.
In order to measure a coordinate in a particular direction on a resistive touch screen, a resistive layer needs to be biased: one side of it is connected to VREF and the other side is grounded. Also, connect the unbiased layer to the high impedance input of an ADC. When the pressure on the touch screen is large enough to make contact between the two layers, the resistive surface is divided into two resistors. Their resistance is proportional to the distance from the touch point to the offset edge. The resistance between the touch point and the ground side is equivalent to the one below the voltage divider. Therefore, the voltage measured on the unbiased layer is proportional to the distance from the touch point to the ground side. The advantage of the resistive touch screen is that its screen and control system are relatively cheap, the reaction 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 completely isolated working environment, not afraid of dust. And water vapor, can adapt to a variety of harsh environments. It can be touched with any object and has better stability.