Membrane keyboard uses and advantages

A guide to membrane keyboard design, options, and industries

In the world of industrial and technological innovation, manufacturers are constantly seeking efficient and reliable input solutions for their products. In many industries, the membrane keyboard has become the preferred solution. This guide gives you an overview of the intricacies of membrane keyboards, exploring their design, functionality, applications, and the benefits they offer to manufacturers and end-users.

A membrane keyboard is made up of multiple layers and utilizes a thin, flexible membrane as the primary mechanism for registering keystrokes. This membrane, typically made of silicone rubber or similar materials, contains conductive traces arranged in a matrix pattern. Overlying this membrane is a layer of keycaps, usually made of plastic or rubber, each with a protruding dome that compresses the underlying membrane when pressed.

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medical device with a membrane keyboard

Design and key 0peration: inner workings of a membrane keyboard

The key operation of a membrane keyboard is relatively simple yet effective. When a key is pressed, the dome collapses, causing the conductive traces on the membrane to come into contact, completing an electrical circuit and registering the keystroke. The keys act as a plunger: as a certain key is pressed down, the key pushes the membrane to the bottom layer of the keyboard which causes the assigned switch to close. The elasticity of the membrane will cause the key to return to its original position when the finger pressure is released. This design results in a quiet typing experience with minimal tactile feedback compared to mechanical keyboards, making membrane keyboards ideal for environments where noise reduction is a priority.

The layers of membrane keyboard

A membrane keyboard is manufactured in layers. Each layer allows for a mechanical contact to register a press command and to close a switch so an elecrical current can flow. The main layers are:

  • The top layer contains all the keys and can be made of plastic or rubber.
  • Below the keys are pressure pads made of thin, flexible rubber or plastic with printed conductive traces on the backside.
  • The "holes" layer separates the pressure pad from the bottom layer 
  • The bottom layer contains printed conductive traces connected to the keyboard’s circuit.
finger touching a long travel keyboard on a computer
low travel membrane keyboard

Full travel vs. low travel membrane keyboards

On a membrane keyboard, the distance a key needs to travel in order to fully depress and send a command to the computer’s brain is the travel distance. This distance is measured in millimeters. The decision of optimal travel distance generally comes down to personal preference, and there are several options to meet your needs.

Full travel membrane keyboards are the type of membrane keyboard usually seen in computers. They're an economical option because their keys are directly integrated into the keypad and are made of a single piece of plastic or rubber material. Most full travel membrane keyboards have a spring underneath each key. The keys on a full travel keyboard will drop down to 3.0mm or higher before bottoming out (when a key reaches its full depth), with the standard distance of a full travel keyboard being around 4mm. Longer key travel is better for most people in terms of accuracy. Not only does longer travel help prevent accidental keystrokes, but it also cushions your fingers from hard presses. Full travel membrane keyboards feature a tactile feedback similar to traditional mechanical keyboards, offering a satisfying typing experience with distinct key travel and feedback. These keyboards are ideal for applications where users prioritize tactile sensation and accuracy, such as industrial control panels or medical devices requiring precise input.

On the other hand, low travel membrane keyboards feature a shallower key press, providing a more compact and lightweight design suitable for space-constrained environments and portable devices. Low travel keyboards have a key distance of around 1.0 to 2.5mm. That means it takes less pressure or effort to press the key down. If you’ve ever used a scissor-switch keyboard, you’ll notice that the keys are usually almost flush with the base. Scissor-switch keyboards use a rubber dome with a plastic scissor mechanism that links the keycap to a plunger. The rubber dome is depressed by the plunger, which shortens the travel distance of the keypad. The “scissor legs” of a scissor-switch keyboard shorten the travel distance of the keys, the rubber dome, and the membrane during a keystroke, prolonging the service life of the keyboard. Scissor-switch membrane keyboards can be noisier than other keyboards due to their reduced amount of rubber cushioning, but they're popular for their durability, with a lifespan rating of 10 million keystrokes.

With shorter or low travel keyboards, sometimes it’s difficult to know when a key is being pressed down. Despite this, low travel membrane keyboards offer reliable performance and durability, and they’re usually smaller, more portable, and quieter than a full travel membrane keyboard.

Anti-ghosting technology

Membrane keyboards have seen significant advancements in recent years, including the integration of anti-ghosting technology. The primary function of a keyboard is to register keystrokes, but inexpensive membrane keyboards have been known to skip inputs—especially if multiple keys are being pressed at the same time. In membrane keyboards, ghosting can occur due to the matrix layout of the key switches, where certain combinations of keys may cause the keyboard to misinterpret input signals.  

Anti-ghosting technology helps make sure that all keystrokes are quickly and accurately registered in the order in which they’re pressed. By incorporating anti-ghosting technology, membrane keyboards can accurately detect and register multiple key presses, ensuring seamless and reliable performance in high-demand applications like gaming, industrial keyboards, and data entry.  

industrial environment cons of adaptive user interfaces AUIs

Advantages of membrane keyboards

Membrane keyboards offer manufacturers several advantages:

Cost. They're more cost-effective to manufacture compared to mechanical keyboards since they have a more basic design and fewer components.

Portability. From industrial control panels and medical devices to consumer electronics and automotive interfaces, slim and lightweight membrane keyboards can be seamlessly integrated into various products, enhancing user interaction and experience.

Durability. The absence of individual mechanical switches reduces the risk of mechanical failure and ingress of dust or debris, ensuring reliable operation even in harsh industrial environments. Additionally, membrane keyboards are often spill-resistant, thanks to their sealed construction, further enhancing their suitability for demanding applications.

vehicle infotainment membrane keyboard on wheel
vehicle infotainment membrane keyboard

Membrane keyboard industries and applications

The versatility and adaptability of membrane keyboards make them indispensable in a multitude of industries and applications.

Healthcare. In the healthcare sector, membrane keyboards are commonly found in medical equipment such as patient monitoring systems, diagnostic devices, and laboratory instruments. The smooth, sealed surface of membrane keyboards facilitates easy cleaning and disinfection, essential for maintaining strict hygiene standards in healthcare settings.

Industrial. In industrial automation and control systems, membrane keyboards play a crucial role in facilitating human-machine interaction. Their robust construction and resistance to dust, moisture, and temperature extremes make them ideal for use in manufacturing plants, process control panels, and machinery interfaces, where reliability and longevity are paramount.

Automotive. In the automotive industry, membrane keyboards are widely used in vehicle dashboards, infotainment systems, and control panels. Their compact design, customizable layouts, and compatibility with backlighting technologies allow automotive manufacturers to create sleek and intuitive interfaces that enhance driver comfort and convenience while ensuring safety on the road.

Membrane keyboards: a cost-effective and durable user interface option 

Membrane keyboards represent a versatile and low-cost input solution across various industries. Manufacturers can leverage the benefits of membrane keyboards to optimize product design, enhance user experience, and drive innovation. At Nelson Miller Group, we offer a range of custom membrane keyboard options to cater to diverse industry needs and user preferences.

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About NMG 

NMG has more than 85 years of experience partnering with organizations to bring their industrial, IoT, lighting, medical, telecommunications, consumer, and aerospace products to life. We solve your most complex challenges in engineering design, manufacturing, and supply chain management.  

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