Input systems – HMI

What is an HMI, input system or an embedded system?

An HMI or human-machine interface enables interaction between the operator (user) and the electrical device or machine. This interaction can take on different forms: From a pure display function, e.g. a classic monitor frame, to a multimodal HMI system that combines haptic, visual and acoustic input and feedback options with computing power and other features.

Conceptually, an input system is a part or the complete HMI, depending on how the evaluation, communication and computing power within the machine is designed. In this context, HMIs can be designed from embedded systems to full-fledged (I) PCs. The difference is that in the embedded case, the function of the system is limited or optimized to the execution of the specific device tasks, while the PC version offers a much broader range of services.

Eingabesysteme HMI
Eingabesysteme HMI

HMI or input system from EP

Eingabesysteme HMI

An HMI or input system is very much defined by its main input method. A specialty of EP are multimodal HMI systems which combine the various input and output methods (e.g. touch, button and display) in one control unit.

In terms of input technologies, we can offer the following options as standard:

Multitouch or capacitive touchscreens

Since the triumph of the iPhone, multi-touch screens have become an integral part of modern operating concepts. Even with professional users, e.g. in the industrial or medical technology environment, capacitive touchscreens are state-of-the-art today. Normally, a multi-touch is implemented with a glass front, but we can also offer equipment with a front film for areas of application that are sensitive to glass breakage, such as the pharmaceutical, food and packaging industries.

Multi-Touchscreen- Touchsysteme

Single touch or resistive touch screens

The inexpensive and mechanically operating predecessor of the Multitouch has retained its following in demanding environments. One advantage is the simple integration into a completely closed film surface which, especially in cleaning-intensive applications, such as in food or medical technology, has the penetration of cleaning or operating fluid.

Eingabesysteme HMI

Membrane keys (with haptic or visual feedback)

Classic key elements with haptic feedback can be integrated particularly well into a flexible film. The design can be with switching element (and embossing)

  • Snap disk (inexpensive variant,> 1 million guaranteed switching cycles)
  • Short-stroke switch (“full” switching feel, lighting easy to implement)

or without a switching element by means of a dome embossing (cheapest variant).

Eingabesysteme HMI

Capacitive buttons (with visual feedback)

Capacitive buttons, usually behind a glass front, can be implemented relatively easily using printed conductive silver or a circuit board. The illuminated variant, with corresponding visual feedback, was a little more complex so far. With the introduction of carbon nanotubes (CNT), full-surface lighting has also become much easier.

Eingabesysteme HMI
Eingabesysteme HMI


Push buttons are independent buttons, e.g. emergency stop buttons, which are normally mounted through the (otherwise closed) front of the HMI input system. Due to their independent structure, these buttons can have a number of additional properties (safety circuits, lighting, multi-level switching processes, etc.)

Eingabesysteme HMI
Oberflächen aus Glas

For output technologies, we can offer as standard:


With TFT-LCD displays, the diagonal, resolution and aspect ratio are the first decisions that have to be made. By default, we use 4.3 “to 24” in widescreen format (16: 9) or 5.7 “to 23” in 4: 3 format. Then you should decide on the appropriate display technology: depending on the requirements of the application such as the required viewing angle, contrast sharpness or price, you have to choose between TN (Twisted Nematic), IPS (In-Plane Switching) or VA (Vertical Alignment) panels. Finally, a few details such as long-term availability, connection options, etc. ., to be clarified before a first decision can be made.

Eingabesysteme HMI

Status lights selectively, flat and all around

In addition to the display, various types of status lights can also be used for visual feedback. The types differ mainly according to their geometry, but can all be dimmable and color-coded across the entire RGB spectrum:

  •  Selective illumination: the classic LED behind the film or glass can be implemented as the smallest geometry with transparent or translucent printing (“disappearing effect”).
  •  Ambientlight or circumferential status light: Only with EP can we also offer a circumferential status light (“Ambientlight”). With the appropriate construction, all RGB colors can be dimmed and implemented up to protection class IP69.
  •  Extensive illumination: Status bars in different geometries require a light guide, but can be integrated behind the front so that the IP protection class is also maintained.
Eingabesysteme HMI
Eingabesysteme HMI

In addition to these input and output options, we integrate other functions and components into our HMI input systems as standard:

Front or carrier plates, housing and display brackets:

The mechanical components that give the HMI or input system its mechanical and structural strength can be made of metal or plastic:

  • Front or carrier plates as well as housings or back covers are one of our core competencies.
  • We can provide housings or carrier plates made of plastic on request.
  • We can also manufacture structural parts inside the HMI input system from metal or plastic. For small and medium-sized series, we like to use our in-house 3D printing to create precisely fitting, space-saving and inexpensive structural components.
HMI Eingabesysteme