A touch chip is a microprocessor that can sense human touch and can convert human touch operations into electrical signal input that can be read by a computer. It is widely used in various digital devices such as mobile phones, tablets, and smart watches, and has become an indispensable part of modern electronic products.
“Touch” specifically refers to single-point or multi-point touch technology; the chip is an IC, which refers to a metal or non-metal sheet whose end surface can be integrated with the friction lining and friction material layer, and a circuit module that integrate a variety of electronic components on a silicon board to achieve a specific function. It is the most important part of electronic equipment, responsible for computing and storage functions. The application scope of integrated circuits covers almost all electronic equipment for military and civilian. A small piece of silicon containing integrated circuits, often is a part of a computer or other device.
Touch chip, also called touch IC. “Touch” refers to single or multi-touch technology. The touch chip is located between the touch sensor and the PC/or embedded system controller. The chip can be mounted on a controller board inside the system or placed on a flexible printed circuit (FPC) attached to the glass touch sensor. The chip extracts information from the touch sensor and converts it into information that the PC or embedded system controller can understand. Most touch chips now use the capacitive effect, that is, the proximity of the human body will increase the capacitance, thereby changing the original oscillation frequency or changing the charge and discharge time of the RC circuit.
How the touch chip works
This is achieved by sensing capacitance changes caused by human touch. When the human body approaches the touch screen surface, it will cause the capacitance between the touch screen and the human body to change, and a new electric field distribution will be formed. The chip will calculate the specific touch position and operation gesture based on this capacitance change. This process requires the use of a series of advanced sensor technologies, signal processing, algorithm optimization and other technologies to achieve high precision and sensitivity.
Touch chips basically use four multi-touch technologies
1. “LLP (laser light plane) technology” mainly uses infrared laser equipment to project infrared rays onto the screen. When the screen is blocked, infrared light is reflected, and a camera under the screen captures where the reflection goes. After systematic analysis, a response can be made.
2. “FTIR (Frustrated Total Internal Reflection) technology” will add LED light to the interlayer of the screen. When the user presses the screen, the light in the interlayer will cause different reflection effects. The sensor will receive the changes in light and capture the point of force application to react.
3. “ToughtLight technology” uses projection method to project infrared rays onto the screen. When the screen is blocked, infrared light is reflected, and a camera under the screen captures where the reflection goes. After systematic analysis, a response can be made.
4. “Optical Touch technology”, which has a lens at each end of the top of the screen to receive the user’s gesture changes and the position of the touch point. After calculation, it is converted into coordinates and then reacted.
How many chips does the touch chip have?
1. Capacitive touch chip: Uses the capacitive principle to detect charge changes on the touch screen, with high accuracy, fast response, and supports multi-touch.
2. Resistive touch chip: It uses the principle of resistance to detect voltage changes on the touch screen. It is cheap, but does not support multi-touch, has low accuracy and short service life.
3. Acoustic wave touch chip: Uses acoustic wave sensors to detect sound reflections on the touch screen, which can support non-contact touch, but is sensitive to environmental noise and other interference.
4. Optical touch chip: Using optical sensors to detect optical changes on the touch screen has high accuracy, but is expensive and not suitable for large-scale applications.
5. Pressure-sensitive touch chip: Uses a pressure-sensitive sensor to detect pressure changes on the screen and supports multi-touch, but the price is higher.
Types of touch chip
1. Channels: single channel, dual channel and multi-channel; that is, the touch chip can support one touch button, two touch buttons or multiple touch button functions;
2. Sensitivity adjustment: A key parameter of the touch button is sensitivity. There are two adjustment methods. One is to change the sensitivity capacitance value outside the touch chip, and the other is to adjust the sensitivity by modifying the parameters of the touch chip through software;
3. Touch type: normal type and sliding scroll bar type; the normal type is a single-touch function, and the sliding scroll bar type is a touch function that can be realized by sliding your finger, similar to the sliding unlocking form of a mobile phone;
4. Interface mode: The interface mode with MCU microcontroller includes ordinary IO pins, SPI communication and IIC communication, etc.;
5. Packaging type: Single channel is generally SOT-23-6, dual channel is generally SOP-8, multi-channel is generally SOP-14, SOP-20, SSOP-28, etc.