Do you still remember the button-based “senior phones” by Daming Lake?
Back then, it was nothing like today.
Nowadays, everyone has a touchscreen phone in their hands.
Whether it’s the elderly, children, office workers, or students…
Everyone has a smartphone with a touchscreen.
We can’t go anywhere without our phones.
Why did the old senior phones not respond to touch on the screen?
Do you know how the touchscreen of a mobile phone works?
What is a Touchscreen?
The touchscreen (TouchPanel) is also known as a touch panel, which is a sensing LCD device that can receive input signals from touch points. When a graphical button on the screen is touched, the tactile feedback system on the screen can drive various connected devices based on pre-programmed instructions, replacing mechanical button panels and creating vivid audio-visual effects through the LCD display.
Dr. Samuel Hurst invented a touch sensor in 1971, which was the prototype of the touchscreen. Three years later, he designed the first transparent touchscreen. In 1977, touchscreen technology saw significant improvements and has been widely used and rapidly developed to this day.
Touchscreens are generally divided into two types: resistive touchscreens and capacitive touchscreens.
Resistive Touchscreen
The resistive touchscreen consists of a multi-layer composite film, with a layer of glass or acrylic as the base layer, coated with a transparent conductive layer, and covered with a hard, smooth, scratch-resistant plastic layer. The inner surface is also coated with a conductive layer, and there are many tiny transparent spacers between the two conductive layers to keep them apart.
When a finger touches the screen, the normally insulated two conductive layers make contact at the touch point, as one conductive layer connects to a 5V uniform voltage field in the Y-axis direction, causing the detection layer’s voltage to change from zero to non-zero. The controller detects this connection, performs an analog-to-digital conversion, and compares the obtained voltage value with 5V to determine the Y-axis coordinate of the touch point, and similarly, the X-axis coordinate can be derived.
Capacitive Touchscreen
The capacitive touchscreen does not rely on finger pressure to change voltage values for coordinate detection. The capacitive screen works through any object that holds a charge, including human skin (the charge carried by the human body). Capacitive touchscreens are made of materials such as alloys or indium tin oxide (ITO), with charges stored in a grid of micro capacitors thinner than a hair. When a finger touches the screen, it absorbs a small amount of current from the contact point, causing a voltage drop at the corner electrodes, allowing the detection of the weak current from the human body to achieve touch functionality.
This is the principle behind our mobile touchscreens, but most of our current mobile touchscreens are capacitive, as this type of touchscreen has a lower error rate and is more suitable for our current usage.
Source: Compiled from the internet
Editor: Little Editor ZZ
Guidance: WCB, YJ
Wuhan Jiang’an District Science and Technology Association
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