Touch switch for voice chip

The principle of touch switch is triggered by the induced voltage of human body, because a lot of electromagnetic waves in our environment will make human body generate induced voltage.Because of the induction voltage to trigger the touch switch input three level tube (usually high input impedance COMS tube) to make it conduction, thus controlling the circuit switch.

There are many types of touch switches. The following are the points I have made:

1, double piece conductive switch: the front end is two electrodes, the inside is a amplifying circuit, the finger touch the current formed in the two electrodes amplification, and drive the back circuit, switch or control function.

2, resistance film or conductive film pressure sensitive switch: this switch is realized by the three-layer structure,

 the upper layer and the lower layer between the conductive sheet clip a support lattice, computer keyboard and ordinary household lighting switch is generally this structure, in fact, and the light touch switch is still a category, but people can hardly feel the journey.

3, mechanical light touch switch: in our life, the common switch, button switch, but after the improvement of the short trip, need to press the distance is small.

4. Capacitance touch switch: this is a common switch for our voice chip. The capacitance formed by a specially shaped PCB(printed circuit board) is used as the trigger condition for touch.SLOPE circuit or frequency voltage conversion circuit is adopted to judge capacitance change and finally determine whether there is finger touch.

Regarding the speech chip may design above each kind of touch switch, the application domain is widespread, for example: the digital product, the electronic speech toy, the education electron, the high class gift box and so on.