Light Guide Module Structure

Light Guide Component usually consist of a bottom reflective layer, light guide layer, dispersion layer, top light shielding layer, and a light blocking layer. Light Guide Components with complex structures can be stacked with multiple layers of LGF (Light Guide Film), and double-sided tape and other materials are added for structural stacking combination.

Reflective Layer is usually a black and white film with adhesive or a double-sided white film to reflect light. The material is usually PET (Polyethylene Terephthalate).

Light Guide Layer is usually a medium layer that guide the propagation of light. Material is usually PC (Polycarbonate) and TPU (Thermoplastic Polyurethane).

Dispersion Layer is usually to reduce focus of light. Material is usually PET.

Light Shielding Layer is usually a black and white film with glue to prevent the spread of light from the top. Material is usually PET.

Light Blocking Layer is for structures with high light leakage requirement. This is an additional layer that can be added to prevent leakage of light. Material is usually black foam glue or black double-sided tape.

Touch Screen LGF Module Structure

This type of LGF optical module is assembled on the bottom surface of the touch panel (TP). It is printed on the TP with a positioning line or a fixture assembly. It is then bonded with the TP through LGF’s own adhesive. The module usually comes with a FPC (Flexible Printed Circuit) + LED light source that is compatible with other PCs, reflective layers and light shielding layers. Only one LED is needed to achieve the uniformity of a 3 characters backlight brightness on a smartphone.

This module technology is widely used in the current mobile phone industry that requires assembly modularity, high integration and full bonding technology of ultra-thin structure. It reduces the disturbance of other structural parts on the optical effect. It has a high and stable energy utilization that can be easily assembled by the customer.

LGF Structure with Buttons

The structure is fixed on metal dome switches by glue bonding. Point light sources emitted by LEDs (more than 2) in the PCB/FPC at different direction (side/top) enter the optical material in parallel (usually 0.1-0.125mm optical PC).

By designing the optical dots/patterns on the LGF, the refraction and complete reflection conditions are changed so that the point light source can be transmitted to the area requiring light transmission, forming surface light on multiple small area.

This type of LGF structure provides good optical effect and is widely used in mobile phone, remote controls, membrane switches and other button electronic products that requires button backlight.

Touch Screen LGF Structure (Top or Side Emitting LED)

The LGF is on different planes with the LEDs accompanied by spatial layering distance in between the assembly structure.

Generally, the bottom will have 2 to 4 top-emitting LED point light sources projected to the optical PC on the upper layer. PC material is generally 0.125, 0.175, or 0.2mm. The upper light-shielding layer then reflect light into the inside of the PC material. The design on PC material will enable areas that requires light transmission achieve the effect of backlight illumination.

The technology is widely used in the mainstream ultra-thin and pricy smart phone touch screen as characters’ backlight.