¡¡¡¡The basic principle of the touch screen is to use your fingers or other objects to touch screen display installed in front of the touch screen when the touch location (in coordinate form) from the touch screen controller testing, and through the interface to the CPU, to determine the input. Touch systems typically include touch screen controller and touch detection device . Among them, the touch screen controller's main role is from the touch point detection device to receive touch information and convert it into contact coordinates, and then sent to CPU, it also can receive commands to sent to the CPU and executed. Touch detection position is usually installed in front of the monitor, the main role is to detect a user's touch position, and send it to the touch screen controller.

¡¡¡¡Resistive touch screen panel with a display part of the body surface to match the multi-layer composite film by a layer of glass or plexiglass as a surface coated with a layer of transparent conductive layer, above and then covered with a layer of the outer surface hardening, anti-smooth scratch the plastic layer, its surface is also coated with a layer of transparent conductive layer, conductive layer between two layers of transparent many of the small isolated points separate them insulation. When the fingers touch the screen, two mutually insulated conductive layer usually keep in touch with a contact point, because of  a conductive layer connected to the Y axis 5V uniform voltage field, making the detection of the voltage from zero to non-zero, which was connected to the state controller to detect, for the A / D conversion, and will be the voltage value can be compared with the 5V and touch the Y-axis coordinates, the same reason, the coordinates of the X-axis This is the resistive touch screen technology for all the common basic principles. Resistive type touch screen is the key material science and technology, how much resistance the number of screens under the Lead, is divided into four lines, wireless, six lines are multi-wire resistive touch screen. Resistive touch screens were painted two OTI transparent conductive metal oxide layers in the glass surface, the outermost layer of OTI is a conductive coating, the second level of precision through OTI is attached to the network .anyway in both directions of the voltage field, between two layers of OTI transparent to small isolated point separated. When the fingers touch screen, two OTI conductive layer will be a contact point, the computer simultaneously detect voltage and current, calculates the location of touch, the response rate is 10-20m / s

¡¡¡¡Five-wire resistive touch screen of the outer conductive layer scalability is a good use of nickel-gold coating materials, due to the frequent touch, conductive outer layer use a good ductility nickel deposit materials in order to extend the service life, but the technology costs are higher. Although the nickel deposit conductive layer scalability, but only for transparent materials, not suitable as the face of resistance touch screen, as it high conductivity, and very uniform thickness of the metal is not easy to do, not as a voltage distribution layer, only as a layer of explore

¡¡¡¡Resistive touch screen is a completely isolated working environment from the outside world, it is not afraid of dust and water vapor, which can be used to touch any object can be used to draw and write, more suitable for industrial control field and office limited use. Resistive touch screen is a common drawback that the outer layer of composite thin films of plastic material, does not know too sharp or the use force likely to scratch the touch screen touch scrapped as a result. However, in the limits, it will only scratch injured outside the conductive layer, the outer conductive layer of the scratch for the five-wire resistive touch screen is not related, and four-wire touch screen is fatal.

¡¡¡¡2.Capacitive touch screen technology is the use of the body of the current sensors to work. Capacitive touch screen is a four-line with glass screen, the inner surface of the sandwich glass coated with a layer of the ITO, the outer protective layer is already thin glass, laminated ITO coating as a face, the four corners Lead electrodes, the inner layer of ITO as a shield to ensure a good working environment. When the fingers touch the metal layer, the electric field because the human body, users, and a capacitive touch screen surface for high-frequency current, the capacitor is the conductor directly, so fingers away from the contact point of a small current. The current from the four corners of the touch screen on the outflow of electrodes, and flows through four electrodes with a finger to the four corners of current proportional to the distance, the controller through the four current precise than the column calculated touch points position.

1. The features capacitive touch screen as follow£º

¡¡¡¡Has the resistance for most of the environmental pollutants
¡¡¡¡Body has become a line which is a serious drift.
¡¡¡¡Does not work with gloves
¡¡¡¡Need to be calibrated
¡¡¡¡Not apply to metal cabinet
¡¡¡¡When the outside world inductance and magnetic sense, make touch screen failure

¡¡¡¡Infrared touch screen is the use of X, Y direction to detect clouds and infrared matrix locate the user's touch. Infrared touch screen in front of the monitor frame to install a circuit board, circuit board arranged on the screen edges and infrared receiver infrared emission control tubes, one to one to form if they had crossed the infrared matrix. Users touch the screen, the finger will be blocked if they had been the location of two infrared, which can determine the location of touch points on the screen. Any object can change the contact on the touch-infrared and achieved operation of touch screen. Infrared touch screen will not be effected by current, voltage and electrostatic interference, poor environmental conditions suitable, infrared touch screen technology is the development trend of the final product, the use of acoustic and other touch screen technology, materials science has insurmountable barrier. Infrared touch screen as long as achieve the truly of high stability and high resolution, it will replace the other touch screen technology products and become mainstream. Infrared touch screen resolution of infrared determined by the framework’s number of tubes, so lower resolution, the market's major domestic products of 32 * 32,32 * 40, in addition to infrared light of environmental factors on the comparison screen sensitive to changes in illumination when large misjudgment or even crash. These are precisely the non-infrared touch screen foreign sales agents promote the domestic weakness of the infrared screen. The latest fifth-generation infrared technology screen resolution depends on the number of infrared tubes, scanning frequency and the difference between the algorithms, resolution of 1000 * 270 screen .As infrared instability in the lighting conditions, from the start the second generation infrared touch screen to have better resistance to light interference . Fifth-generation IR touch screen is a new generation of smart technology products, which implements the 1000 * 720 resolution, multi-level self-regulation and self-healing capabilities and highly intelligent hardware to adapt to the judge recognized, it can be a long time in harsh environments and arbitrary use for custom extensions. A major shortcoming of original infrared touch screen media is antiknock poor, in fact, it can use any infrared screen make satisfaction of our customers without adding too much proof glass, the cost and impact of performance, that is the other can not follow.

¡¡¡¡Taking the lower right corner of the X-axis transmitter as an example: the launch transducer can control via the touch screen cable into electrical signals and sent to the left of the surface acoustic energy, and then by a group of precision glass bottom reflection stripes the acoustic energy reflected into a uniform face-up transfer, acoustic energy through the screen surface, and then the reflection from the top right of the line of striped together into a spread to the X-axis receiving transducer, receiving transducer will return to the surface acoustic wave energy into electrical signals. When the transmitter transducer is transmitting a narrow pulse, the acoustic energy received through various channels to reach the transducer, and take the first right to reach and take the far left of the latest arrival, the earliest arrival and the latest arrival of acoustic energy change into a more width of the waveform signal. Therefore, the timeline reflects the waveform overlay of the original wave front location, which is the X-axis coordinates. Transmitted signal and received signal waveforms in the absence of touch when receiving the signal and reference waveforms exactly the same waveform. When the finger or other acoustic energy to absorb or block objects touch screen, X-axis go through finger positions up to be part of the received acoustic energy absorbed, reflected in the received waveform that is said on a time position £¬there is a wave attenuation gap. Received waveform corresponding to parts of signal attenuation finger blocking a gap, that is, to calculate the touch location of coordinates£¬ and  the controller receives the signal attenuation and analysis to the location of the gap determined by the X coordinate. After the same process£¬ Y-axis determine to its position, in addition to the general touch screen response of the X, Y coordinates, the surface acoustic wave touch panel also responded to the third axis Z-axis coordinate, which is capable of sensing the user touch-pressure size value. The principle is that the received signal attenuation at the attenuation calculated. When axis is established, controller put them to the host.