a covering member at least comprising an upper cover and a lower cover, which are combined together;

a transparent keycap exposed outside through a first opening of the upper cover;

an elastic element attached on the transparent keycap;

a first electrode installed on the elastic element;

a key circuit board assembly with a second electrode, wherein the first electrode and the second electrode are aligned with each other and electrically connected with each other, so that a capacitive structure is formed by the first electrode and the second electrode collaboratively, wherein when the transparent keycap is pressed down, the elastic element is correspondingly moved, and a spatial distance between the first electrode and the second electrode is changed, so that at least one capacitance change value is formed, wherein the key circuit board assembly generates at least key press information according to the at least one capacitance change value;

a display panel aligned with a first perforation of the key circuit board assembly and the transparent keycap; and

a main control board electrically connected with the key circuit board assembly and the display panel, wherein the main control board issues at least one key function visual information to the display panel, and the at least one key function visual information is visible through the transparent keycap, wherein the at least key press information is inputted into the main control board, and the main control board generates and outputs at least one key function control command according to the at least key press information;

wherein the elastic element comprises a second perforation;

wherein the first electrode is distributed and disposed on at least a part of one of a first surface region and a second surface region of the elastic element;

wherein the first electrode is distributed on a periphery region of the second perforation of the elastic element;

wherein the elastic element is arranged between the upper cover and the key circuit board assembly, the first surface region of the elastic element is located beside the upper cover, and the second surface region of the elastic element is located beside the key circuit board assembly.