Advantages of membrane keyboards

Membrane keyboards are still justified

In the food, laboratory and medical sector, the membrane keyboard plays due to the closed surface, resistance to chemicals and impermeability to liquids and dust also currently play an important role. N&H Technology from Willich has been producing membrane keyboards for all industries for over 20 years.

Preferred choice not only in the medical field

Especially in devices with a small number of functions, which at the same time require good visibility and are in constant user interaction membrane keyboards the preferred choice. In the medical field, these are, for example, nurse emergency call systems, hospital bed controls, input keyboards for diagnostic devices and defibrillators as well as other interfaces for patient care. Many of these input devices are also operated by inexperienced users such as older patients, so that a complex Touch input solution is rather disadvantageous.

Design options for membrane keyboards

membrane keyboards can through the diverse design options with a user-friendly and intuitive interface serve. With the use of tools, the membrane keyboard can take on almost any shape. In addition to the common screen printing process, the realization of Color gradients and digital printing for prototypes and small series. Specially embossed films can even be used metallic effects achieve, for example, brushed stainless steel or anodized aluminum. Another advantage over display solutions is that the printed surface and optionally integrated LED status indicators can also be seen from a 180° rotated viewing angle.

Membrane keyboards impress with their flat design

The flat construction membrane keyboard consists of a film composite made up of at least four films: the decorative film, the upper and lower switching film and a spacer film. The decorative film is the top layer of the keyboard and is made of polyester or polycarbonate. It is printed on the back to ensure the highest possible protection against abrasion.

Compared to other flexible materials, polyester is particularly impressive with its long life cycle of over one million switching cycles, very high abrasion resistance and very good resistance to chemicals.

The front foil can be equipped with an antibacterial coating for applications in the medical field and in areas with high hygienic requirements. This antimicrobial polyester kills or inhibits bacterial growth and provides constant protection against bacterial contamination.

Functional elements of a membrane keyboard

The functional elements of the membrane keyboard are the lower circuit membrane with the printed conductors, LEDs, switching points and the connection lug located on it, as well as the upper circuit membrane with the contact surfaces. The spacer foil acts as an insulator, separating the upper and lower switching foils or, in the case of a version with metal snap-action discs, acts as a fixing foil.

Illuminated membrane keyboards

Depending on the needs of the application, backlight options vary. Especially in the often darkened work environments in the medical field, illuminated key fields are necessary in order to find important key functions without any problems. LEDs can be easily integrated into the existing switching membrane or, if required, into an additional one LED switch foil be introduced.

Special adhesives and sealing materials are used to ensure the function of the LED even in harsher environments with, for example, strong vibrations. The backlighting of a membrane keyboard can be achieved by using LGF (Light Guide Film) take place. The typically flat design and flexibility are retained. With LGF technology, LEDs are inserted at the edge into a very thin (0,1 to 0,2 mm), highly refractive film. Due to the high refraction of light, very few LEDs are required for homogeneous illumination, depending on the size of the membrane keyboard.

The backlighting each button can be in different colours take place. In contrast to EL backlighting, LGF technology does not require a high-frequency AC voltage source. A special feature are labels with a disappearing effect. This is an inscription that cannot be seen when the keyboard is not illuminated and is only visible when it is illuminated. This can be used to signal a clear on/off mode.

Tactile feedback

Another benefit of the membrane keyboard is the tactile feedback of the button function to the user. Snap-action discs provide a noticeable feeling of touch when actuated and, depending on the version, an audible cracking noise. This direct feedback can reduce file entry errors. Metal domes come in a variety of sizes, shapes and actuation forces and are preferred for applications with a high number of actuations.