G+F+F Structure in Capacitive Touch Panel
G+F+F refers to the “Glass + Film + Film” structure, which is a touch panel design that combines glass and flexible film. Specifically:
Upper Glass (G): Usually tempered glass (e.g. Corning Gorilla Glass) is used as the outermost layer of the touchscreen, providing high hardness, scratch resistance and durability, and the user touches this layer directly.
Intermediate Film (F): A layer of PET film with a transparent conductive layer (e.g. ITO or metal grid) used to detect touch signals.
Lower film (F): Another layer of PET film, also with a conductive layer, is used in conjunction with the middle layer to form the X/Y axis touch sensing matrix.
Bonding Layer: Optical Clear Adhesive (OCA) is used to bond the glass to the film and the film to the film to ensure light transmission and touch sensitivity.
How the G+F+F structure works
The conductive layer forms an electrostatic field: the conductive lines of the middle and lower films are responsible for signal detection in the X-axis and Y-axis respectively, forming an electrostatic field that covers the entire screen.
Finger touch to change the electric field: when the finger contact screen, will change the local capacitance value, affecting the electric field distribution.
Controller calculates the touch point: After the touch chip detects the capacitance change, it calculates the exact position of the touch (X/Y coordinates) through an algorithm and transmits it to the device to execute the operation.
Compared to other structures (e.g. G+G, F+F, OGS, etc.), the main advantages of G+F+F include:
High sensitivity: F+F capacitive touchscreens are more sensitive due to the use of a thin film as the conductive layer. The film layer is able to respond more flexibly to touch events and even light touches can be detected accurately.
Low cost: Compared to capacitive touchscreens with a G+G (Glass+Glass) structure, the G+F+F structure utilizes a thin film material, which is less costly and suitable for mass production.
Adaptable: G+F+F capacitive touch screen can be adapted to various shapes and sizes of design needs, with high flexibility. It can be bent or cut into various shapes to fit the appearance requirements of different devices.
The G+F+F structure combines the durability of glass with the flexibility of film, and is suitable for devices that require high surface hardness and a good touch experience, but don't want to use all-glass (G+G), such as mid- to high-end flat panels, automotive displays, and industrial control devices. It strikes a better balance between cost, durability and display effect.