Different technical principles between touch screens
The touch screen computer requires little storage space, few moving parts, and can be packaged. The touch screen is more intuitive to use than the keyboard and mouse, and the training cost is also very low.
All touch screens have three main components. The sensor unit that processes the user's selection; and the controller that senses touch and locates, and is driven by a software device that transmits touch signals to the computer operating system. There are five technologies for touch screens: resistive touch, capacitance touch, infrared touch, acoustic wave technology or near-field imaging technology.
Resistive touch screens usually include a flexible top film and a layer of glass as the base layer, which is isolated by insulating points. The inner surface coating of each layer is transparent metal oxide. The voltage has a difference in each diaphragm. Pressing the top film will form an electrical contact signal between each resistive layer.
Capacitive touch screens are also coated with transparent metal oxides, which are bonded to the single-layer glass surface. It is not like a resistive touch screen, any touch will form a signal, a capacitive touch screen needs to be touched directly with a finger or in contact with a conductive stylus. The capacitance of the finger, or the ability to store charge, can absorb the current in each corner of the touch screen, and the current flowing through the four electrodes is proportional to the distance from the finger to the four corners, thereby obtaining the touch point.
The infrared touch screen is based on light interruption technology. Instead of placing a film layer in front of the display surface, it sets a frame around the display. The outer frame has a light source, or light emitting diode (LED), located on one side of the outer frame, and a light detector or photoelectric sensor on the other side, forming a horizontal and vertical cross infrared grid in a one-to-one correspondence. When an object touches the display screen, the invisible light is interrupted, and the photoelectric sensor cannot receive the signal, thereby determining the touch signal.
In the acoustic wave sensor, the sensor is installed on the edge of the glass screen to send ultrasonic signals. Ultrasonic waves reflect through the screen and are received by the sensor, and the received signal is weakened. In surface acoustic wave (SAW), light waves pass through the surface of the glass; while in guided acoustic wave (GAW) technology, sound waves pass through the glass.
The Near Field Imaging (NFI) touch screen consists of two thin glass layers with a transparent metal oxide coating in the middle. When an AC signal is applied to the lead-point coating, an electric field is generated on the surface of the screen. When a finger, whether wearing gloves or not, or other conductive stylus touches the sensor, the electric field will be disturbed and the signal will be obtained.
As the current mainstream touch technology, the capacitive touch screen all-in-one machine not only has an exquisite appearance and a streamlined design, but also has a smooth screen in use, with ten fingers operating at the same time. Touchwo touch all-in-one machine is more competitive than its peers.