Articles about the future of classic keyboards, membrane keypads and silicone keypads
Published in PC & Industry 10/2020
One might think that the conventional keyboard as an input element has its golden days behind it. In the telecommunications sector, it still ekes out its existence in landline telephones, while the mobile sector has had to be handed over almost entirely to smart display technologies. Because it is precisely through the integration of multi-touch screens that mobile end devices, where the use of a mouse and keyboard is rather impractical, can exploit their full potential.
The graphic visualization options create interactive communication experiences for the user in line with the company's corporate design. Logical visualizations and clear designs make even complex menu structures easy to use.
The requirement to make the interface between man and machine uncomplicated and intuitive is also driving further and faster development in the area of gesture control, eye tracking and voice control. User-related input errors are to be eliminated and the safety of operation increased. This also makes touch displays very popular for applications in home automation, kiosk systems or plant and machine control.
Google, Siri or Alexa
It remains to be seen whether, in five or ten years, people will still need a haptic input interface as we currently understand it. It's been a long time since we've pressed the play button to listen to music or, thanks to modern smart home integration, to turn on the light switch. A small request to Google, Siri or Alexa is enough. More AI-driven technologies will set the trend in the future.
While Generation Y and older grew up with a multitude of hardware systems that today's generations only know from hearsay and see the use of a keyboard as an everyday occurrence, future generations might smile at this as nostalgic use. Just think of the further development of calculating machines in the last 50 years or the development of the first mobile telephones - all not too long ago.
Keyboard status quo
In the status quo, however, input keyboards are absolutely justified and should be used as an alternative or supplement depending on the area of application touch systems and Co. Especially in devices with a small number of functions that require good visibility and are in constant user interaction, proven input components such as Membrane keyboards, silicone keypads and push buttons, the preferred choice – also in terms of cost. The financial outlay for programming a graphical user interface between humans and machines is a significant factor. It's true that not everything that's technically possible is also economically viable.
Classic keyboards - Can be used anywhere
membrane keypads and silicone keymats Due to their closed surface, resistance to chemicals and their tightness to liquids and dust, they are currently used in almost all industries. In the medical field, membrane keypads can be found, for example, in 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 tends to be disadvantageous.
The keyboard is also evolving
Due to constant further development, the membrane keypad but not to be seen as a pure switching solution. Rather, it is a combination of sophisticated design, special coatings and equipment extras such as integrated LEDs or an integrated touch panel. Membrane keyboards can be used with a user-friendly and intuitive interface thanks to their diverse design options. Through the use of tools, it can take any form.
In addition to the common screen printing process, digital printing is particularly suitable for the realization of color gradients and for prototypes and small series. Specially embossed foils can even be used to achieve metallic effects such as brushed stainless steel or anodised aluminium. Another advantage compared to display solutions is that the printed surface, as well as optionally integrated LED status displays, can also be seen from a viewing angle rotated by 180°.
Flat structure of the membrane keypad
The flat structure of a membrane keypad consists of a composite film made up of at least four films: the decorative film, the upper and lower switching film and a spacer film. The decorative foil as the top layer of the keyboard consists of polyester or polycarbonate and is printed on the back to ensure the best possible protection against abrasion. In comparison with other flexible materials, polyester in particular is impressive with a long life cycle of over 1 million switching cycles, very high abrasion resistance and resistance to chemicals.
For applications in the medical sector and areas with high hygiene requirements, the Front film with an antibacterial coating This antimicrobial polyester kills or inhibits bacterial growth and provides constant protection against bacterial contamination. Functional elements of the membrane keypad are the lower switching foil with the printed conductors, LEDs, switching points and the connection lug located on it, as well as the upper switching foil with the contact surfaces.
Backlight for membrane keypads
Depending on the application-specific requirements, the Backlight optionsg. Illuminated keypads are particularly necessary in dimly lit work environments to easily locate important functions. Embossed keypads can provide additional support here. LEDs can be easily integrated into the existing keypad or, if necessary, incorporated into an additional LED keypad. Special adhesives and sealing materials are used to ensure the LEDs function even in harsh environments with, for example, strong vibrations.
The backlighting of a membrane keypad can through the Use of LGF (Light Guide Film) The typical flat design and flexibility are retained. With LGF technology, LEDs are embedded at the edge of a very thin (0,1–0,2 mm), highly refractive film. Due to the high light refraction, depending on the size of the membrane keypad, only a very few LEDs are required for homogeneous illumination. Each key can be backlit in different colors.
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 allows a clear ON / OFF mode to be signaled.
Tactile feedback from a membrane keypad
Another benefit of the membrane keypad is the tactile feedback to the user. Snap domes provide a noticeable tactile sensation when actuated and, depending on the model, an audible "click." This direct feedback reduces file entry errors. metal domes are available in a variety of Sizes, shapes and actuation forces and are preferred for applications with a high number of actuations. Membrane keyboards without metal snap domes can also provide tactile feedback by using an embossed design.
The embossing can be done on both the decorative foil and the upper switching foil. Key, dome and edge embossing These allow for highly ergonomic key shapes. Embossed keys also provide finger guidance. Keys are given a particularly sophisticated look by applying a high-quality epoxy coating, which gives the key a three-dimensional appearance. The combination of snap domes and key embossing is common.
Silicone surface - the hybrid keyboard
In addition to the proven variants of different, superimposed film layers, there is the option of replacing the upper polyester film with a silicone surface. Silicone cover with buttons can be laminated as a pure actuation layer onto the circuit package of a normal membrane keypad. The resulting Hybrid of classic membrane keypad and silicone keymat gives scope to combine the advantages of the individual input solutions in one keyboard.
The silicone surface allows for a three-dimensional design, a point where membrane keypads are naturally very limited. This allows for raised keys with free-form shapes, guiding elements such as offset rings around a key, Braille labels, or cursor keys. At the same time, the surface is enhanced visually and haptically.
Combination of membrane keypad and touch screen
If more functionality or a more complex operating menu is desired, a combination of membrane keypad and modern Touchscreen solutions .
An additional keypad next to the touch screen promotes user-friendly menu navigationby allowing input commands or preset parameters to be accessed easily and clearly. With appropriate programming, the fixed keys can also perform dynamic functions, depending on the respective menu.
For the version with touch screens or display displays, Viewing window in the membrane keypad integrated. Depending on requirements, these can be individually specified, including matte, scratch-resistant, UV-resistant, and colored. The membrane keypad and touch screen are bonded together using a highly transparent adhesive layer with a light emission level of >99%. This process prevents the formation of Newton's rings.
A similar combination is also with silicone keymats possible. The Key layout injected directly onto the plastic front frameThis creates an optimal bond between the two components. The display and electronics are combined with the resulting frame in a subsequent processing step. The advantage of multi-component injection molding technology is that only one component needs to be constructed. This leads to significantly reduced investment and effort in production and quality assurance.
silicone keymat
The single, classic silicone keymat is still one of the most common switching elements in the electronics and automotive industries. It is used millions of times every day simply by operating a remote control. However, for medical applications, where good cleanability of input elements is required, the silicone keymat consist of a closed surface.
As the central component, it triggers a direct switching function on the circuit board underneath and determines the haptics, the visual and tactile impression and the electrical behavior via the integrated contact elements. In addition, the switch mat often have a sealing function on the circuit board. Their mechanical Service life with up to 10 million switching cycles makes it a long-lasting and almost maintenance-free input solution. It adapts to your design and is extremely flexible and space-saving. Keycaps made of metal and plastic, different key shapes and individual key colors can be easily implemented in a mat.
The illumination of individual keys Illumination of the entire mat is possible using LEDs combined with transparent silicone or integrated light guides. A highly precise 2K injection molding process also allows for multi-color keyboard illumination. This process allows for the integration of a light channel into each individual key. This light channel is completely isolated from the rest of the transparent key, achieving precise focusing of the light beam. Switch mats using this technology can now not only be backlit, but the individual keys can also display status indicators.
Adjustable force-displacement behavior
The force-displacement behavior of a silicone keymat can be customized to the requirements of the respective application. Actuating forces from 20g to 500g and Actuation travel from 0,3 to 5,0mm The implementation options for the electrical contacts range from cost-effective yet secure carbon printing to high-quality metal contact pills with a Current carrying capacity up to 2 AThe silicone keypad is particularly advantageous when large quantities are required. The high one-time costs for the tools make small series production very cost-intensive. However, compared to individual pushbuttons, they are significantly more cost-effective, even for medium-sized series.
Vandalism-proof input buttons
In the public space or local transport, as well as in industrial machine controls continue to play vandalism-proof input buttons a role that ensures precise and reliable operation, as well as quick traceability. The buttons often take on the function of a pure command transmitter, so that signals such as start and stop or forward and reverse movement are clearly communicated. With engraved or printed lenses, colored Satus LEDs and various housing colors, pushbuttons can also be given an individual look. Multicolored lighting even allows multicolored status indications to be displayed.
The buttons are made of robust plastic or metal and installed directly into a front panel and a housing. Appropriate seals ensure a Protection class up to IP68 / IP69K. The service life of up to 1 million cycles also makes the buttons very reliable. A longer service life is offered by Piezo button, which are made of metal.
By eliminating a mechanical stroke, wear and contamination are almost eliminated. Service life of over 50 million cycles make them very reliable and virtually maintenance-free. They are used in areas where damage from vandalism is to be expected or where they are exposed to heavy environmental stress.
Miniaturization and design of keyboards
The increasing demand for miniaturization and design orientation plays an important role in each of these proven electromechanical operating units. Buttons with low installation depths, membrane keypads with extensive equipment and a flat structure at the same time reflect the trend. The end devices should be flatter, thinner and lighter, but miniaturization in the input area is also reaching its limits, after all the devices still have to be usable by humans. Touch screens and voice control, paired with further developments in the field of artificial intelligence (AI), are becoming increasingly present precisely because they are already an essential part of our everyday lives.
In the status quo, however, innovative control elements with a combination of the proven electromechanical control units and modern touch panels continue to ensure exciting further developments, also with regard to an increasing addition of gesture controls.
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