Touch Panel, also known as "touch screen" and "touch panel", is an inductive liquid crystal display device that can receive input signals such as contacts.
The haptic feedback system can drive various connection devices according to pre-programmed programs, which can be used to replace the mechanical button panel, and create vivid audio-visual effects through the liquid crystal display screen.
Advantages and Disadvantages of Four Touch Screens As a newest computer input device, touch screen is a simple, convenient and natural way of human-computer interaction.
It gives multimedia a new look and is a very attractive new multimedia interactive device.
Mainly used in public information query, industrial control, military command, video games, multimedia teaching, etc.
According to the type of sensor, touch screen is roughly divided into four types: infrared type, resistive type, surface acoustic wave type and capacitive touch screen.
Advantages and disadvantages of four touch screens:
1. The infrared technology touch screen is cheap, but its outer frame is fragile, easy to produce light interference, and distorted in the case of curved surfaces;
2. The capacitive technology touch screen has a reasonable design concept, but its image distortion problem is difficult to fundamentally solve;
3. The positioning of the resistive technology touch screen is accurate, but its price is quite high, and it is afraid of being scratched and damaged;
4. The surface acoustic wave touch screen solves various defects of the previous touch screen. It is clear and not easy to be damaged. It is suitable for various occasions.
The infrared touch screen is equipped with a circuit board frame in front of the display, and the circuit board is arranged with infrared emission tubes and infrared receiving tubes on the four sides of the screen, forming a horizontal and vertical infrared matrix in one-to-one correspondence.
When the user touches the screen, the finger will block the horizontal and vertical infrared rays passing through the position, so the position of the touch point on the screen can be determined.
Any touch object can change the infrared rays on the touch point to realize touch screen operation.
The infrared touch screen is immune to current, voltage and static electricity, and is suitable for some harsh environmental conditions.
Its main advantages are low price, easy installation, no cards or any other controllers, and can be used in computers of various grades.
In addition, since there is no capacitor charging and discharging process, the response speed is faster than that of the capacitive type, but the resolution is lower.
The outermost layer of the resistive screen is generally a soft screen, and the inner contacts are connected up and down by pressing. The inner layer is equipped with a physical material oxide metal, that is, an N-type oxide semiconductor - indium tin oxide (Indium Tin Oxides, ITO), also called indium oxide, with a light transmittance of 80%. ITO is the main material used in both resistive touch screens and capacitive touch screens. Their working surface is the ITO coating. Press the outer layer with fingertips or any object, so that the surface film is concavely deformed, so that the two inner layers of ITO collide and conduct electricity for positioning. To the coordinates of the pressing point to realize the control. According to the number of lead-out lines of the screen, there are 4-wire, 5-wire and multi-wire, the threshold is low, the cost is relatively cheap, and the advantage is that it is not affected by dust, temperature and humidity. The disadvantage is also obvious. The outer screen film is easily scratched, and sharp objects cannot be used to touch the screen surface. Generally, multi-touch is not possible, that is, only a single point is supported. If two or more contacts are pressed at the same time, the precise coordinates cannot be recognized and found. To enlarge a picture on the resistive screen, you can only click "+" multiple times to gradually enlarge the picture. This is the basic technical principle of the resistive screen.
Control using pressure sensing.When a finger touches the screen, the two conductive layers are in contact at the touch point, and the resistance changes.
Signals are generated in both X and Y directions and then sent to the touch screen controller.
The controller detects this contact and calculates the (X, Y) position, and then behaves according to the way of simulating a mouse.
The resistive touch screen is not afraid of dust, water and dirt, and can work in harsh environments.
However, because the outer layer of the composite film is made of plastic material, the explosion resistance is poor, and the service life is affected to a certain extent.
The resistive touch screen is controlled by pressure sensing. Its surface layer is a layer of plastic, and the bottom layer is a layer of glass, which can withstand the interference of harsh environmental factors, but has poor hand feel and light transmittance. It is suitable for wearing gloves and those that cannot be directly touched with hands occasion.
Surface acoustic waves are mechanical waves that propagate along the surface of a medium.
The corners of the touch screen are equipped with ultrasonic transducers.
A high-frequency sound wave can be sent across the surface of the screen. When the finger touches the screen, the sound wave on the touch point is blocked, thereby determining the coordinate position.
The surface acoustic wave touch screen is not affected by environmental factors such as temperature and humidity. It has high resolution, scratch resistance, long life, high light transmittance, and can maintain clear and bright image quality. It is most suitable for use in public places.
However, dust, water and dirt will seriously affect its performance and require frequent maintenance to keep the screen clean.
4. Capacitive touch screen
This kind of touch screen uses the current induction of the human body to work. A layer of transparent special metal conductive material is pasted on the glass surface. When a conductive object touches, the capacitance of the contact will be changed, so that the position of the touch can be detected.
But there is no response when touched with a gloved hand or holding a non-conductive object because of the addition of a more insulating medium.
Capacitive touch screen can sense light and fast touch well, anti-scratch, not afraid of dust, water and dirt, suitable for use in harsh environments.
However, since the capacitance varies with temperature, humidity or environmental electric field, it has poor stability, low resolution, and is easy to drift.
Post time: Nov-04-2022