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.
HMI or input system from EP
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.
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.
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).
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.
Pushbuttons
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.)
For output technologies, we can offer as standard:
Displays
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.
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.
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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.
Display controller boards
The display must be supplied with the appropriate data signals and energy. A display controller board is required for this, which converts the input signals HDMI, DVI, DP etc. (mostly) into LVDS and at the same time supplies the backlight with the appropriate voltage.
Sensors
Nowadays, an HMI no longer only reacts to physical actuation by users, but rather records events and data from its environment via various sensors. Most often, the following sensors are used, which are integrated almost invisibly into the input system (i.e. at least still have IP65):
RFID reader
(e.g. enable fully automatic and contactless identification)
Brightness sensors
(e.g. enable the automatic adjustment of the button brightness depending on the ambient conditions)
IR sensors
(enable e.g. motion detection or remote control)
Electric wire
In the end, the internal components must all be connected to each other in order to be able to communicate with each other. Depending on the components used, we can support you with standard or customer-specific cables of all design variants (FFC, FPC, stranded wire, etc.).
We are happy to support you with your input system or HMI project. If you are interested, you can contact us directly using the contact form at the end of the page.
You might also be interested in :
Capacitive touchscreen (multitouch)
Membrane keyboards
Back to the product overview
Single touch screen
Touch systems
Glass surfaces
Surfaces made of foils
EP Electronic Print
Kirschstr.18
80999 Munich
Phone: +49 (0)89 /89 70 44 0
Fax: +49 (0)89 /89 70 44 44
Email: info@ep-electronicprint.de