Backlighting Options For A Custom Silicone Rubber Keypad

Backlighting Rubber Keypad

Backlighting rubber keypad is the most common silicone rubber keypad design.Backlighting rubber keypad also called as backlit rubber keypad, illuminated membrane switch keypad.It is widely used in electronic products such as remote controls, industrial keyboards, medical devices, calculators and many other small electronic products.

When you are designing a backlighting rubber keypad, you should consider the how to achieve backlighting.That is to say how to design the light guide source on PCB.

The raw material of rubber keypad is silicone which is clear and support backlighting.But, during the design, there are several types of backlighting.

LED Illumination

Light-emitting diodes(LEDs) are usually used to for illuminated silicone keyboards light guide. LED backlighting are widely because of long lasting and energy saving properties. 

While, when you design LED light guide, its location and size should be considered well.Generally speaking, the LEDs are designed to put under the centre of each rubber buttons, so that it can illuminate the whole buttons.

For the LED illuminated rubber keypad, it usually choose conductive ink printing.Because conductive ink printing is not limited by shapes.

Carbon pill is also available.But the standard carbon pill is round shape.It need to do extra tool to achive customized ring-shaped carbon pill.

For the LED illuminated rubber keypad, it usually chosse conductive ink printing.Because conductive ink printing is not limited by shapes.

Carbon pill is also available.But the standard carbon pill is round shape.It need to do extra tool to achive customized ring-shaped carbon pill.

Stardard Round-shape Carbon Pill for LED Illumination                                                                 Customized Ring-shape Carbon Pill for LED Illumination

LGF Illumination

In addition to LEDs, light guides can be used to illuminate a silicone rubber keypad from underneath. They are made up of a transparent material (glass or plastic) and thin filaments and are capable of transmitting light signals though internal reflections.As their name suggests, they are designed to distribute light by “guiding” it.The backlighting solution produces illumination, whereas the light guides distribute the light throughout the silicone rubber keypad.

This backlighting technology uses a thin light guide film or LGF. The right-angled LEDs produce the light and the LGF directs this light across an area that is supposed to be highlighted. It is possible to fabricate the LGF in various shapes. Therefore, it is possible to use this type of back lighting option with a custom rubber keypad with equal efficiency. This film also provides consistent backlighting.

                                          Backlit Rubber Remote Control Keyboard By LGF Illumination

LGF is also widely used for membrane switch illumination.LGF illumination membrane switches mean that there is light source from the side LEDs to light the graphic overlay and provide the indication information to users or when the product is used in the night or dark environment.

Since membrane keypads are very thin and are partly built into a housing in a curved state.Light guide film is good choice for membrane switch.Homogeneous backlighting can be achieved with membrane keyboards as with plastic light guides for other input systems. The full backlighting of the film is achieved with just a few LEDs. This saves costs and creates a more visually appealing effect.

Fiber Optic Illumination

Fiber optics is also used in silicone rubber keypad backlighting.

Fiber optics is the technology used to transmit information as pulses of light through strands of fiber made of glass or plastic over long distances.

is similar to light guide backlighting in that both types involve the use of thin glass or plastic strands. Like LED, fiber optic backlighting is energy efficient and long-lasting.

EL Illumination

Finally, we would like to introduce electroluminescent (EL) backlighting method. It is a physical phenomenon in which an electric field is generated by the voltage applied to two electrodes, and the electrons excited by the electric field collide with the emitting light center, resulting in the transition, change and recombination of electrons between energy levels.That’s to say it is a physical phenomenon that converts electrical energy directly into light energy.So compared to LED illumination, EL illumination requires higher power drive.

The EL backlight emits a single color.And only can choose one type of color.Its brightness is relatively more uniform than LED illumination.It provide rubber keypad a sufficient amount of illumination to enhance the appearance and performance