Panel PC display sizes explained: which size suits your application?

Industrial panel PCs usually range from about 7 inches (approx. 17.8 cm) to 24 inches (approx. 61 cm) screen diagonal. The ranges can be grouped roughly as follows:

• 7 to 10 inches: compact devices for simple control tasks where space is limited
• 10.1 to 15.6 inches: the mid-range for classic HMI and machine control applications
• 17 to 24 inches: larger displays for complex visualisation and control station applications

Industrial displays larger than 24 inches also exist. However, they are more likely to be found in custom solutions than in the standard portfolios of most manufacturers.

GETT covers this range with the four product lines of its InduSmart® series :

The number of controls, status values and charts that need to be displayed at the same time largely determines the screen area required. A rule of thumb from HMI design: regardless of display size, touch targets should not be smaller than about 10 to 15 mm, so that operators can hit them reliably under real operating conditions.

If the application has to show more information, there are two options: a larger display or a user interface divided into several levels. Both have consequences. More levels mean longer navigation paths and potentially longer operating times. A larger display needs more installation space and more power.

Whether content looks sharp and can be read without strain depends on resolution and pixel density (measured in PPI, pixels per inch) in combination with the viewing distance. At a greater distance, a lower pixel density may be sufficient. For close-up operation, fine details quickly look blurred without a higher resolution.

Brightness – measured in nits or candela per square metre – is also key to readability under changing light conditions. In bright production halls or near windows, higher brightness is needed to prevent loss of contrast caused by stray light.

Optical bonding also helps: the air gap between the cover glass and the display is filled with a transparent adhesive layer. This significantly reduces internal reflections and improves readability in strong ambient light as well as contrast in direct sunlight. An anti-glare coating, also referred to as AR coating, further reduces glare on the glass surface.

The display size directly determines the front cut-out required in the control cabinet, console or housing, as well as the installation depth behind the front panel. Larger displays usually also need more depth for electronics, heatsinks and connectors – an important point where space is tight. The bezel width (the frame around the active display area) also affects how closely several panel PCs can be mounted side by side. The following mounting options are typically available:

The choice of touch technology is closely linked to the planned display size and the operating environment.

Projected capacitive touchscreens (PCAP) offer high optical clarity and support multi-touch gestures. They are used throughout the InduSmart® series. In industrial environments, PCAP touchscreens typically reach a protection rating of up to IP65 at the front. For reliable operation with thick work gloves, however, they often need specially tuned sensors or compatible gloves.

Resistive touchscreens work on the basis of pressure. They therefore reliably detect any kind of input – including thick gloves, styluses or wet fingers. This makes them the preferred choice in certain outdoor and warehouse environments, even though their optical clarity and multi-touch capability are lower than those of PCAP solutions.

When selecting a touch technology, you should therefore always consider – and ideally test – the type of glove actually used on site.

Besides the diagonal and touch technology, the panel type also affects image quality. IPS (in-plane switching) panels offer wide viewing angles and stable colours even when viewed from the side. This is an advantage for operating stations with several viewers at the same time or with an elevated installation position. The RedLine series uses high-resolution IPS displays throughout, with wide viewing angles and high brightness for good readability on the factory floor.

VA panels offer higher contrast but somewhat narrower viewing angles. TN panels mainly stand out for short response times and low cost, but show stronger colour and contrast shifts when viewed from the side.

In machine and plant engineering, medium display sizes between 10.1 and 18.5 inches are most common, as usually only a limited number of controls and status displays have to be shown at the same time.

For premium solutions with high design requirements and customised controls, the BlackLine with 18.5 or 21.5 inches is a suitable choice. Its robust metal housing with IP65 protection at the front, IP54 at the rear and an illuminated capacitive button bar was developed specifically for demanding machine environments. An emergency stop button can also be integrated directly into the control bar.

In food production, cleanrooms and medical environments, cleanability and sealed housing designs with as few joints as possible take priority. Mid-range display sizes between 10.1 and 15.6 inches are typical here. Larger glass surfaces tend to show more contamination and cleaning marks and also place higher demands on the mechanical stability of the glass.

Glass surfaces without joints or recesses make cleaning with disinfectants much easier and reduce the risk of microbes accumulating in gaps. Medical electrical equipment is also subject to the IEC 60601 series of standards, which sets specific requirements for electrical safety and interference immunity. These must be taken into account when selecting a panel PC for medical applications.

Control stations and monitoring centres usually need the largest display sizes available, between 18.5 and 24 inches, as several process visualisations, key figures and alarm messages have to be shown in parallel. The longer viewing distances in control station environments also allow larger displays without compromising ergonomics.

With Intel® Core™ i5 processors, features for compute-intensive applications such as SCADA, MES and production dashboards, and comprehensive connectivity, RedLine and BlackLine are well suited to control station systems and central operating stations of complex plants.

Outdoor use and vehicle manufacturing bring additional requirements for brightness, glare reduction and mechanical stability. Direct sunlight requires higher brightness as well as measures such as optical bonding and anti-glare coating to prevent loss of contrast caused by stray light.

The mechanical impact resistance of the front panel is often specified using the IK rating according to IEC 62262. IK07 to IK09 are common for displays on machines with continuous vibration and occasional mechanical contact, while IK10 is mainly used for publicly accessible terminals or terminals at risk of vandalism. In vehicle manufacturing, display sizes usually depend on the space available in the cab and are often in the compact to mid-range between 7 and 12 inches.

The choice of display size also affects the total cost of ownership (TCO). Using the same display size across several generations of machines reduces the effort for spare parts stock and simplifies follow-up projects, as the user interface and the mechanical cut-out stay the same.

For long-life machine projects, obsolescence management is particularly important. This means actively tracking when a particular display size or panel technology will be discontinued on the market. GETT addresses this risk with documented long-term availability of up to 7 years for the BlackLine, based on the form-fit-function principle. Display size and operating logic therefore remain available for reordering, unchanged, throughout this period. GETT also documents a return rate of 0.21% across its entire portfolio, which can serve as an indicator of actual manufacturing quality and reliability in the field.