Classification and introduction of LCD touch screen
1. Capacitive LCD touch screen
Capacitive touch screen is mainly constructed by coating a transparent thin film body layer on the glass screen and adding a protective glass outside the conductor layer. The double glass design can completely protect the conductor layer and inductor.
Capacitive touch screen is plated with narrow electrodes on the four sides of the touch screen to form a low voltage alternating current electric field in the conductive body. When the user touches the screen, due to the electric field of the human body, a coupling capacitor will be formed between the finger and the conductor layer. The current generated by the electrodes on the four sides will flow to the contact. The current strength is proportional to the distance from the finger to the electrode. The capacitive touch screen's double glass protects the conductor and sensor and prevents environmental factors from affecting the touch screen. Even if the screen is stained with dirt, dust or oil, the capacitive touch screen can still accurately calculate the touch position.
2. Iinfrared LCD touch screen
The principle of infrared touch screen is very simple, just add blip distance frame on the display, without coating the surface of the screen or connecting the controller. Infrared emitting and receiving tubes are arranged on the four sides of the blip from the frame, forming an infrared network on the screen surface. When a user touches a point on the screen with his finger, it blocks two infrared rays that pass through it. The computer can calculate the position of the touch point in time. Infrared touch screen is free from current, voltage and electrostatic interference, suitable for some harsh environmental conditions. Its main advantages are low cost, easy installation, no need for card or any other controller, can be used in all levels of computers.
3. Surface acoustic liquid crystal touch screen
The touchscreen portion of a surface acoustic touch screen can be a flat, spherical, or cylindrical glass panel mounted in front of a CRT, LED, LCD, or plasma display screen. The glass panel is pure reinforced glass and unlike other touch-screen technologies does not have any film or coating. The upper left corner and the lower right corner of the glass screen are fixed with vertical and horizontal ultrasonic transmitting transducers, and the upper right corner is fixed with two corresponding ultrasonic receiving transducers. The four sides of the glass screen are engraved with very precise reflection stripes from thin to close intervals at 45° angles.
4. Resistance technology LCD touch screen
Touch screen body parts is a very cooperate with multi-layer composite membrane, and display surface by a layer of glass or organic glass as a base, surface coated with a layer of transparent conductive layer (the OTI, indium oxide), the above with a layer of surface hardening treatment, smooth and scratch-resistant plastic layer, its inner surface is coated with a layer of the OTI, in between two layers of conductive layer, there are many small (less than one over one thousand of an inch) of transparent isolation point separates them insulation. When A finger touch screen, A contact point in both the OTI conductive layer, with one side of conductive layer on the Y axis for 5 v voltage field, makes the detection layer voltage from zero to A nonzero, controller to detect the connected, A/D conversion, and will be compared with 5 v voltage value, can have to touch the Y coordinate of the point in the same way it is concluded that the coordinates of the X axis, which is the basic principle of resistance touch screen technology together. According to the number of outgoing lines, the resistance screen is divided into four lines, five lines and other multi-line resistance touch screen.