Key input device and method based on piezoelectric effect

Abstract

The invention relates to a key input device and method based on piezoelectric effect. The device comprises a key, a voltage comparator and a microcontroller. A piezoelectric material is arranged under the key; the first input end of the voltage comparator is connected with the piezoelectric material, the second input end is input with a reference voltage, and the output end is connected with the input end of the microcontroller; the piezoelectric material generates a first voltage when the key is pressed by an external force; the voltage comparator compares the first voltage and the reference voltage, and outputs a rectangular wave signal according to the comparison result; and when the microcontroller judges that the rectangular waves are effective rectangular waves, the microcontroller outputs a key value of the key corresponding to the effective rectangular wave signal. The key input device utilizes the piezoelectric effect of the piezoelectric material and adopts a pressure deformation quantity detection mode to realize key function, judges whether the pulse signals are effective signals through the microcontroller, and can filter various shaking interference and environment shake interference, and thus accurate input of the key is realized.

Description

technical field [0001] The invention relates to the field of key control, in particular to a key input device and method based on piezoelectric effect. Background technique [0002] There are two types of existing key input devices, one is to control key input through mechanical contacts, and the other is to control key input by touch. [0003] The key input is controlled by a mechanical contact, which is usually realized by a transmission switch device with a contact on-off of a traditional mechanical structure, such as a micro switch. It has the advantages of simple circuit, mechanical feel and strong anti-interference ability in terms of electromagnetic compatibility (EMC). However, the mechanical contact control button input has the following disadvantages: there is a life limit; the contact is easily affected by the humidity environment and oxidized, resulting in poor contact, resulting in error or failure of the button function; the panel on the surface of the keyboar...

AI Technical Summary

Problems solved by technology

However, the mechanical contact control button input has the following disadvantages: there is a life limit; the contact is easily affected by the humidity environment and oxidized, resulting in poor contact and resulting in error or failure of the button function; the panel on the surface of the keyboard cannot be dustproof, waterproof, and anti-oil. The intrusion of the mechanical button is limited to the design of the selected button and structure; there will be hidden dangers of electric sparks in the switch

However, the capacitive touch screen must have an object with changing capacitance or human body touch to trigger the key response. Although the surface of the key panel can be dustproof, waterproof, and prevent the intrusion of various oils, it may be damaged by water and various oils attached to the surface of the key. , Liquid objects cause the original function of the key to be disordered or invalid. The overall performance of the electromagnetic compatibility (EMC) anti-interference ability is obviously worse than that of the mechanical key, and the panel attached to the keypad can only be made of insulating materials. Panel made of metal

Due to the above shortcomings, it is easy to cause the problem of inaccurate key input

Images