As electronic technology becomes more and more developed, touch screens and touch-sensitive switches have gradually replaced ordinary traditional mechanical switches. After powering on, as long as your finger touches the button sensing area, the switch command will be triggered to make the machine work. But if there is grease on our hands, fingerprints will remain on the key panel over time. Will such fingerprints directly cause the machine to automatically start up? The answer is no, of course not!
Touch-sensitive proximity switches can be divided into resistive touch switches and capacitive touch-sensitive switches. The principle of a resistive touch switch is actually the same as that of a traditional mechanical switch. When pressed, the two contacts conduct, and the current passes through the printed soft circuit to form a closed loop. After receiving it, the CPU issues instructions to make the machine work, and the contacts are automatically disconnected after the finger leaves.
It's just that the touch switch makes the two contacts very close and the stroke is very short, so the key area can be turned on with just a light touch. The fingerprint left on the surface of the key has no pressure on the key, so it has no effect.
The working principle of capacitive touch sensing switches is completely different from resistive switches. The biggest difference is that each button has only one wire connected to the motherboard PCB and does not require a closed loop. The button is equivalent to one capacitor pole of the capacitor, and the other capacitor pole is connected to the IC on the PCB circuit board. When a finger approaches a button from a distance and then touches the button, the entire process will cause the dielectric constant of the capacitor to change. When the IC senses this change, it will know which button was touched and give corresponding instructions to make the machine work. Similarly, fingerprints on the surface of the keys will not cause changes in capacitance and will not trigger the switch function.
Rechan Electronic Technology Co., Ltd. is a manufacturer specializing in the production of capacitive touch sensing proximity switch circuits. The company has an advanced technical team and many years of experience in membrane switch and touch switch design. Use high-quality PET or imported diffusion film and other raw materials, screen-print transparent conductive oil, silver paste, carbon paste, UV, 3M glue, etc.
It is attached to the PC or PMMA acrylic panel on the surface, and the other end is connected to the motherboard PCB with FPC to form a capacitive touch sensing proximity switch. kevin@rechan.com
